JP7732807B2 - film - Google Patents

Description

The present invention relates to a film that can be used as a substrate material for high-frequency printed circuit boards and antenna boards, and a composition that can be used to form the film.

With the widespread adoption of fifth-generation mobile communication systems, known as 5G, there is a demand for printed circuits and printed wiring boards that can be used for antennas and are compatible with high-frequency bands. However, at high frequencies, transmission loss inherent in the substrate material has a significant impact, making it important to select substrate materials that can reduce transmission loss. For example, copper-clad laminates (CCLs) have a structure in which copper foil is laminated to both surfaces of a resin layer via an adhesive. Since the transmission loss of CCLs can be reduced by reducing the dielectric loss, particularly the dielectric loss tangent and relative permittivity, of the resin layer that serves as the transmission path, films with low dielectric loss tangents are being investigated. For example, Patent Document 1 discloses a low-dielectric resin composition containing a resin (A) such as a polyimide resin and a cyclic olefin (co)polymer (B), and a film with a low dielectric loss tangent formed from the composition. However, even films formed from the low-dielectric resin composition described in Patent Document 1 do not necessarily achieve a sufficient reduction in dielectric loss tangent.

Japanese Patent Application Laid-Open No. 2017-125176

The inventors of the present invention conducted research into reducing the dielectric loss tangent and found that films formed from the low dielectric resin composition described in Patent Document 1 may not have sufficient water absorption resistance.

Therefore, an object of the present invention is to provide a film with excellent water absorption resistance and a composition capable of forming such a film.

As a result of intensive research to solve the above-mentioned problems, the present inventors have surprisingly found that in a film containing a polyimide-based resin (A) and a particulate polymer (B), when the lightness L ^* of reflected light of the film, measured by a specular reflection removal method, is 37 or less on both sides of the film, the water absorption resistance of the film can be improved, and have completed the present invention.

That is, the present invention includes the following preferred embodiments.
[1] A film comprising a polyimide-based resin (A) and a particulate polymer (B), wherein the film has a haze of 75% or less and a lightness L ^* of reflected light measured by a specular reflection elimination method of 37 or less on both sides of the film.
[2] A film comprising a polyimide-based resin (A) and a particulate polymer (B), wherein the film has a haze of more than 75% and a lightness L ^* of reflected light measured by a specular reflection elimination method of 80 or less on both sides of the film.
[3] The film according to [1] or [2], wherein the distance between the HSP values of the polyimide resin (A) and the polymer (B) is 6 or more.
[4] The film according to any one of [1] to [3], wherein the particulate polymer (B) has an average primary particle diameter of 15 μm or less.
[5] The film according to any one of [1] to [4], wherein the content of the particulate polymer (B) is 5 to 50 mass% based on the total mass of the polyimide resin (A) and the particulate polymer (B).
[6] The film according to any one of [1] to [5], wherein the polymer (B) is at least one polymer selected from the group consisting of an olefin-based polymer, a polyimide-based polymer, a fluorine-based polymer, a silicone-based polymer, a liquid crystal polymer, an aramid polymer, a styrene-based polymer, and an ether-based polymer.
[7] The film according to any one of [1] to [6], wherein the polymer (B) is a cycloolefin-based polymer.
[8] The film according to any one of [1] to [7], wherein at least one of the glass transition temperature and the melting point of the polymer (B) is 100°C or higher.
[9] The cycloolefin polymer is represented by the formula (I):
[In formula (I), m represents an integer of 0 or greater; R ⁷ to R ¹⁸ each independently represent a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms; when a plurality of R ¹¹ to R ¹⁴ are present, they may be the same or different; and R ¹⁶ and R ¹⁷ may be bonded to each other to form a ring together with the carbon atoms to which they are bonded.]
The film according to [7] or [8], which contains a cycloolefin-derived monomer unit (1) represented by the following formula:
[10] A composition comprising a polyimide-based resin (A), a particulate polymer (B), and a solvent,
The composition comprises a first solvent and a second solvent, and the distance between the HSP values of the second solvent and the particulate polymer (B) is 8.5 or more.

The present invention provides a film with excellent water absorption resistance and a composition capable of forming such a film.

The following describes in detail the embodiments of the present invention. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

〔film〕
The film of the present invention contains a polyimide-based resin (A) and a particulate polymer (B), and when the haze is 75% or less, the lightness L ^* of reflected light measured by a specular reflection removal method (hereinafter, sometimes simply referred to as "lightness") is 37 or less on both sides of the film, and when the film contains a polyimide-based resin (A) and a particulate polymer (B) and the haze is more than 75%, the lightness L ^* of reflected light measured by a specular reflection removal method is 80 or less on both sides of the film.

The inventors continued their research into the water absorption resistance of films and unexpectedly discovered that the water absorption resistance of a film can change depending on the relationship between the film's haze and brightness. Therefore, the inventors conducted further research focusing on the film's brightness, and discovered that a film with excellent water absorption resistance can be obtained by adjusting the brightness of a film with a haze of 75% or less to 37 or less on both sides of the film, and that a film with excellent water absorption resistance can be obtained by adjusting the brightness of a film with a haze of more than 75% to 80 or less on both sides of the film.

On the other hand, if the brightness of at least one side of a film with a haze of 75% or less exceeds 37, the film's water absorption resistance tends to decrease. Furthermore, if the brightness of at least one side of a film with a haze of more than 75% exceeds 80, the film's water absorption resistance tends to decrease. When a film absorbs water, its dielectric properties tend to decrease.

In one embodiment of the present invention, the brightness of a film having a haze of 75% or less is preferably 36.5 or less, more preferably 36 or less, even more preferably 34 or less, and particularly preferably 32 or less, on both sides. When the brightness is below the above upper limit, the water absorption resistance of the film is easily improved. Furthermore, the brightness of the film is preferably 10 or more, more preferably 20 or more, and even more preferably 25 or more, on both sides. When the brightness is above the above lower limit, the film is less likely to become curled, for example, when stored in roll form. The brightness of reflected light measured by the specular elimination (SCE) of the present invention can be measured using a spectrophotometer, for example, by the method described in the Examples. The haze of the film can be measured using a haze meter based on JIS K 7136, for example, by the method described in the Examples.

In another embodiment of the present invention, the brightness of a film having a haze of more than 75% is preferably 78.5 or less, more preferably 78 or less, even more preferably 76 or less, even more preferably 73 or less, and particularly preferably 72 or less, on both sides. When the brightness is equal to or less than the above upper limit, the water absorption resistance of the film is likely to be improved. Furthermore, the brightness of the film is preferably 30 or more, more preferably 40 or more, even more preferably 48 or more, even more preferably 50 or more, and particularly preferably 55 or more, on both sides. When the brightness is equal to or greater than the above lower limit, the film is less likely to become curled, for example, when stored in roll form.

The brightness of the film can be adjusted by appropriately adjusting the film composition, such as the type, composition ratio, and molecular weight of the structural units constituting the polyimide resin (A) and/or polymer (B) contained in the film, the content and composition ratio of the particulate polymer (B) in the film, the particle size, and the film manufacturing conditions. For example, the brightness of the film can be adjusted to within the above range by selecting the type of polymer (B), the type and composition ratio of the structural units constituting the polyimide resin (A) and/or polymer (B), the content and particle size of the particulate polymer (B), and the film manufacturing method, as described below as preferred embodiments. In particular, when the film is formed using the preferred manufacturing method described below, it is easy to adjust the brightness of the film to within the above range. Unless otherwise specified, in this specification, "particle size" includes the average primary particle size and/or median diameter of the particulate polymer (B).

<Polymer (B)>
The polymer (B) is a polymer different from the polyimide resin (A). When the polymer (B) is a polyimide resin, it may be a polyimide resin of a different type from the polyimide resin (A), for example, a polyimide resin having a different type or content of monomer units constituting the resin.

The polymer (B) is not particularly limited, and examples include olefin-based polymers, polyimide-based polymers, fluorine-based polymers, silicone-based polymers, liquid crystal polymers, aramid polymers, styrene-based polymers, and ether-based polymers. Polymer (B) can be used alone or in combination. Using these polymers as polymer (B) facilitates reducing the particle size of polymer (B) and improving dispersibility. Furthermore, using these polymers as polymer (B) facilitates reducing the brightness and coefficient of linear expansion (hereinafter sometimes referred to as CTE) of the resulting film, while enhancing the film's dielectric properties and water absorption resistance. Among these, at least one polymer selected from the group consisting of olefin-based polymers, polyimide-based polymers, fluorine-based polymers, liquid crystal polymers, styrene-based polymers, and ether-based polymers is preferred, with olefin-based polymers being more preferred. At least one polymer selected from the group consisting of polyethylene, high-density polyethylene, polypropylene, polymethylpentene, and cycloolefin-based polymers is even more preferred, with cycloolefin-based polymers being particularly preferred. In this specification, dielectric properties refer to dielectric properties including dielectric loss, dielectric constant, and dielectric loss tangent, and increasing or improving the dielectric properties refers to, for example, a decrease in dielectric loss, dielectric constant, and/or dielectric loss tangent.

In a preferred embodiment of the present invention, the cycloolefin-based polymer is a polymer represented by formula (I):
[In formula (I), m represents an integer of 0 or more,
R ⁷ to R ¹⁸ each independently represent a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms; when a plurality of R ¹¹ to R ¹⁴ are present, they may each independently be the same or different; and R ¹⁶ and R ¹⁷ may be bonded to each other to form a ring together with the carbon atoms to which they are bonded.
It is preferable that the particulate polymer (B) contains a monomer unit (I) derived from a cycloolefin represented by the following formula: Hereinafter, the "particle size of the particulate polymer (B)" may be simply referred to as the "particle size".

In formula (I), m is an integer of 0 or greater. From the standpoints of facilitating reduction of particle size and CTE, facilitating improvement of the water absorption resistance and heat resistance of the film, and being readily available, the upper limit of m is preferably an integer of 3 or less, more preferably an integer of 2 or less, and even more preferably an integer of 1 or less.

Examples of hydrocarbon groups having 1 to 20 carbon atoms that are part of the substituents of R ⁷ to R ¹⁸ include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, octyl, and dodecyl; aryl groups such as phenyl, tolyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and groups in which some of the hydrogen atoms of the above alkyl, aryl, and aralkyl groups have been substituted with halogen atoms. Among these, alkyl, aryl, and aralkyl groups are preferred from the viewpoints of easily improving the water absorption resistance, dielectric properties, and heat resistance of the film and easily reducing the CTE of the film. That is, R ⁷ to R ¹⁸ are preferably hydrogen atoms, alkyl groups having 1 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, or aralkyl groups having 7 to 20 carbon atoms, and more preferably hydrogen atoms or alkyl groups having 1 to 10 carbon atoms.

Examples of cycloolefins represented by formula (I) include norbornene, 5-methylnorbornene, 5-ethylnorbornene, 5-butylnorbornene, 5-phenylnorbornene, 5-benzylnorbornene, tetracyclododecene, tricyclodecene, tricycloundecene, pentacyclopentadecene, pentacyclohexadecene, 8-methyltetracyclododecene, and 8-ethyltetracyclododecene. Among these, norbornene is preferred from the standpoints of ease of availability of the raw material monomer, reduction of particle size and film CTE, and improvement of film heat resistance. Cycloolefins represented by formula (I) may be used alone or in combination of two or more.

In one embodiment of the present invention, the cycloolefin polymer preferably contains a double-chain structure of the monomer unit (I). By containing the double-chain structure, heat resistance is more likely to be improved compared to a polymer having a similar content of the monomer unit (I). The presence or absence of the double-chain structure can be determined by ^13C -NMR spectrum analysis. For example, in the case of a tetracyclodecene-ethylene copolymer, signals derived from an ethylene-tetracyclodecene-ethylene sequence, which is an isolated chain of tetracyclodecene, appear near 54.7 ppm and near 51.1 ppm, signals derived from an ethylene-tetracyclodecene-tetracyclodecene-ethylene sequence, which is a two-chain tetracyclodecene sequence with endo-exo bonds, appear near 51.5 ppm and near 50.8 ppm, and signals derived from an ethylene-tetracyclodecene-tetracyclodecene-ethylene sequence with exo-exo bonds appear near 55.3 ppm and near 54.3 ppm, and therefore, determination can be made based on the signal patterns near 55 ppm and near 50 ppm.

The di-chain structure of the monomer unit (I) includes a meso-type di-chain represented by the following structural formula (II-1) or the following structural formula (II-2), and/or a racemo-type di-chain represented by the following structural formula (III-1) or the following structural formula (III-2).

The ratio of meso-type di-chains to racemo-type di-chains (hereinafter sometimes referred to as meso-type di-chains/racemo-type di-chains) is preferably 0.50 or less, more preferably 0.40 or less, even more preferably 0.30 or less, particularly preferably 0.20 or less, and preferably 0.01 or more, more preferably 0.05 or more. When the ratio of meso-type di-chains to racemo-type di-chains is within the above range, the mechanical properties and heat resistance of the film are likely to be improved. The ratio of meso-type di-chains to racemo-type di-chains can be calculated, for example, using ^13C -NMR based on the assignments described in "R.A. Wendt, G. Fink, Macromol. Chem. Phys., 2001, 202, 3490" and "JP 2008-285656 A", specifically, by the method described in the Examples. In addition, as a method for adjusting the meso-type double chain and racemo-type double chain within the above range, there is a method of selecting a catalyst having an appropriate ligand size relative to the bulkiness of the monomer. As the catalyst, for example, the catalysts described in JP-A-9-183809 can be used. In this specification, mechanical properties refer to mechanical properties including flexural resistance and elastic modulus, and an increase or improvement in mechanical properties means, for example, an increase in flexural resistance and/or elastic modulus.

The content of the monomer unit (I) in the cycloolefin-based polymer is preferably 60 mol% or more, more preferably 65 mol% or more, even more preferably 70 mol% or more, particularly preferably 75 mol% or more, and preferably 100 mol% or less, more preferably 99 mol% or less, and even more preferably 98 mol% or less, relative to the total molar amount of repeating units constituting the cycloolefin-based polymer. When the content of the monomer unit (I) is equal to or greater than the above-mentioned lower limit, the glass transition temperature (hereinafter sometimes referred to as Tg) is easily increased, thereby easily reducing the CTE of the film, and the brightness of the film is easily reduced, thereby easily improving the water absorption resistance. Furthermore, the mechanical properties of the film, such as heat resistance and flex resistance, are easily improved. When the content of the monomer unit (I) is equal to or less than the above-mentioned upper limit, the mechanical properties, such as flex resistance, are easily improved. The content of the monomer unit (I) can be calculated using ¹³ C-NMR based on the assignments described in "RA Wendt, G. Fink, Macromol. Chem. Phys., 2001, 202, 3490", for example, by the method described in the Examples.

From the viewpoint of easily reducing the CTE of the film and easily improving mechanical properties such as water absorption resistance and flex resistance, the cycloolefin polymer preferably contains monomer units (II) derived from at least one selected from the group consisting of ethylene, linear α-olefins having 3 to 20 carbon atoms, and aromatic vinyl compounds having 8 to 20 carbon atoms, and more preferably contains monomer units (II) derived from ethylene.

Examples of linear α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene. Among these, propylene, 1-butene, 1-hexene, or 1-octene is preferred, and propylene is more preferred, from the viewpoint of easily reducing the CTE of the film and easily improving mechanical properties such as water absorption resistance and flex resistance. Linear α-olefins having 3 to 20 carbon atoms may be used alone or in combination of two or more. Note that "linear α-olefin" refers to a linear olefin having a carbon-carbon unsaturated double bond at the α-position.

Examples of aromatic vinyl compounds having 8 to 20 carbon atoms include styrene, methylstyrene, dimethylstyrene, ethylstyrene, tert-butylstyrene, vinylnaphthalene, vinylanthracene, diphenylethylene, isopropenylbenzene, isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, isopropenylnaphthalene, and isopropenylanthracene. Among these, styrene, methylstyrene, or dimethylstyrene is preferred, and styrene is more preferred, from the viewpoints of ease of availability of raw material monomers, ease of reducing the CTE of the film, and ease of improving mechanical properties such as flexural resistance. Aromatic vinyl compounds having 8 to 20 carbon atoms may be used alone or in combination of two or more.

In one embodiment of the present invention, from the viewpoints of easy availability of raw material monomers, ease of reducing the CTE of the film, and ease of improving mechanical properties such as flexural resistance, the cycloolefin-based polymer preferably contains monomer units (II) derived from at least one selected from the group consisting of ethylene, propylene, and styrene, more preferably monomer units (II) derived from at least one selected from the group consisting of ethylene and styrene.

The content of the monomer unit (II) in the cycloolefin-based polymer is preferably 0 mol% or more, more preferably 0.01 mol% or more, even more preferably 1 mol% or more, still more preferably 2 mol% or more, and preferably 40 mol% or less, more preferably 35 mol% or less, even more preferably 30 mol% or less, and particularly preferably 25 mol% or less, relative to the total molar amount of repeating units constituting the cycloolefin-based polymer. When the content of the monomer unit (II) is at least the above-mentioned lower limit, the mechanical properties such as flex resistance of the film, as well as processability and moldability, are likely to be improved. When the content of the monomer unit (II) is at most the above-mentioned upper limit, the CTE of the film is likely to be reduced, and mechanical properties such as water absorption resistance, heat resistance, and flex resistance are likely to be improved.

In one embodiment of the present invention, from the viewpoint of easily improving mechanical properties such as heat resistance, processability, and flexural resistance, as well as water absorption resistance, and easily reducing particle size and CTE, the cycloolefin-based polymer is preferably a cycloolefin-based copolymer, more preferably a cycloolefin-based copolymer containing cycloolefin-derived monomer units (I) represented by formula (I) and monomer units (II) derived from at least one selected from the group consisting of ethylene, linear α-olefins having 3 to 20 carbon atoms, and aromatic vinyl compounds having 8 to 20 carbon atoms, and even more preferably an ethylene-norbornene copolymer containing norbornene-derived monomer units (I) and ethylene-derived monomer units (II), or a styrene-norbornene copolymer containing norbornene-derived monomer units (I) and styrene-derived monomer units (II).

The cycloolefin polymer may contain other monomer units (III). Examples of other monomers constituting the other monomer units (III) include conjugated dienes such as butadiene and isoprene; non-conjugated dienes such as 1,4-pentadiene; acrylic acid; acrylic acid esters such as methyl acrylate and ethyl acrylate; methacrylic acid; methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; and vinyl acetate. The other monomer units (III) can be used alone or in combination of two or more.
The polymer (B) may be used alone or in combination of two or more kinds.

In one embodiment of the present invention, examples of olefin-based polymers other than cycloolefin-based polymers include polymers or copolymers containing the monomer unit (II); the monomer unit (III); at least one monomer unit selected from the group consisting of 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, and vinylcycloalkane; and derivatives thereof. Polyethylene, high-density polyethylene, polypropylene, or polymethylpentene is preferred, and polypropylene or polymethylpentene is more preferred from the viewpoint of improving heat resistance.

In one embodiment of the present invention, the polyimide-based polymer may be, for example, a polyimide-based polymer that is soluble in the first solvent.

In one embodiment of the present invention, the fluoropolymer is a fluorine-containing olefin polymer or a modified product thereof. Specific examples include polymers and copolymers containing at least one monomer unit selected from the group consisting of fluoroolefins, such as tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, vinylidene fluoride, and vinyl fluoride. Examples include polytetrafluoroethylene (hereinafter sometimes referred to as PTFE), perfluoroalkoxyalkane, perfluoroethylenepropene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, and polyhexafluoropropylene. From the perspective of improving the dielectric properties of the film, the fluoropolymer is preferably a polymer having structural units derived from tetrafluoroethylene, and more preferably, the molar ratio of structural units derived from tetrafluoroethylene to the sum of all structural units is 0.25 or more, even more preferably 0.30 or more, even more preferably 0.50 or more, and particularly preferably 0.75 or more. The molar ratio of each constituent unit of the fluoropolymer can be determined by NMR measurement. For calculating the molar ratio, see, for example, Eric B. Twum et al., "Multidimensional 19F NMR Analyses of Terpolymers from Vinylidene Fluoride (VDF)-Hexafluoropropylene (HFP)-Tetrafluoroethylene (TFE)," Macromolecules, 2015, Vol. 48, No. 11, pp. 3563-3576. Furthermore, from the viewpoint of improving solubility in the first solvent, the fluoropolymer may be a copolymer of the above-mentioned monomer unit with at least one selected from the group consisting of vinyl ethers, vinyl esters, and allyl ethers.

In one embodiment of the present invention, the liquid crystal polymer may include a polymer having, as a repeating unit, an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, an aromatic diol, an aliphatic diol, or the like.
Specific examples of monomers that provide aromatic hydroxycarboxylic acid repeating units include aromatic hydroxycarboxylic acids such as parahydroxybenzoic acid, metahydroxybenzoic acid, orthohydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 5-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, and 4'-hydroxyphenyl-3-benzoic acid, as well as alkyl, alkoxy, or halogen-substituted derivatives thereof and ester-forming derivatives thereof. Of these, parahydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are preferred from the viewpoint of easily improving the water absorption resistance, mechanical properties, and heat resistance of the film.

Specific examples of monomers that provide aromatic dicarboxylic acid repeating units include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 4,4'-dicarboxybiphenyl, as well as alkyl, alkoxy, or halogen-substituted versions of these and ester-forming derivatives of these. Among these, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are preferred from the viewpoint of easily improving the water absorption resistance, mechanical properties, and heat resistance of the film.

Specific examples of monomers that provide aromatic diol repeating units include aromatic diols such as hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, and 4,4'-dihydroxybiphenyl ether, as well as alkyl, alkoxy, or halogen-substituted versions of these and ester-forming derivatives of these. Among these, hydroquinone and 3,3'-dihydroxybiphenyl are preferred from the viewpoint of easily improving the water absorption resistance, mechanical properties, and heat resistance of the film.

Specific examples of monomers that provide aliphatic diol repeating units include aliphatic diols such as ethylene glycol, 1,4-butanediol, and 1,6-hexanediol, as well as acylated products of these. Among these, ethylene glycol is preferred because it can easily improve the water absorption resistance, mechanical properties, and heat resistance of the film.

In one embodiment of the present invention, the styrene-based polymer is a resin containing at least one styrene in the repeating structural unit, such as polystyrene, ABS resin (acrylonitrile-butadiene-styrene copolymer), and AS resin (acrylonitrile-styrene copolymer). Of these, polystyrene is preferred from the viewpoint of its ease of improving dielectric properties.

In one embodiment of the present invention, the ether-based polymer is a resin containing at least one repeating unit containing an ether group in the main chain, and examples thereof include polyetherimide, polyphenylene ether, polyethersulfone, polyetherketone, and polyetheretherketone. Among these, polyphenylene ether, polyethersulfone, and polyetheretherketone are preferred from the viewpoint of easily improving the water absorption resistance and dielectric properties of the film.

In one embodiment of the present invention, the weight-average molecular weight (hereinafter, weight-average molecular weight may be abbreviated as Mw) of polymer (B) is preferably 10,000 or more, more preferably 15,000, even more preferably 20,000 or more, even more preferably 30,000 or more, particularly preferably 50,000 or more, especially more preferably 70,000 or more, especially even more preferably 90,000 or more, and is preferably 2,000,000 or less, more preferably 1,000,000 or less, even more preferably 700,000 or less. When Mw is at or above the above lower limit, the water absorption resistance and heat resistance of the film are easily improved, and strength is easily improved. When Mw is at or below the above upper limit, the water absorption resistance, mechanical properties, and formability of the film are easily improved.

In one embodiment of the present invention, the ratio (Mw/Mn) of Mw to number average molecular weight (hereinafter, number average molecular weight may be abbreviated as Mn) of polymer (B) is preferably 2.5 or less, more preferably 2.2 or less, even more preferably 2.0 or less, even more preferably 1.95 or less, particularly preferably 1.90 or less, and preferably 1.30 or more, more preferably 1.50 or more, even more preferably 1.60 or more, particularly preferably 1.65 or more. When the Mw/Mn ratio is below the upper limit, the water absorption resistance and mechanical properties of the film are likely to be improved, while when it is above the lower limit, formability is likely to be improved. Note that Mw and Mn can be determined by gel permeation chromatography (hereinafter, sometimes abbreviated as GPC) measurement and converted into standard polystyrene, for example, by the method described in the Examples.

In one embodiment of the present invention, from the viewpoint of easily obtaining a film with a reduced CTE, the refractive index of polymer (B) is preferably 1.600 or less, more preferably 1.570 or less, even more preferably 1.550 or less, and is preferably 1.500 or more, more preferably 1.520 or more. The refractive index of polymer (B) can be measured using a refractometer, for example, by the method described in the Examples.

In one embodiment of the present invention, the CTE of polymer (B) is preferably 110 ppm/K or less, more preferably 80 ppm/K or less, even more preferably 58 ppm/K or less, even more preferably 55 ppm/K or less, and particularly preferably 50 ppm/K or less, and is preferably 0 ppm/K or more, more preferably 0.01 ppm/K or more, even more preferably 1 ppm/K or more, and even more preferably 5 ppm/K or more. When the CTE of polymer (B) is below the above upper limit, the CTE of the resulting film is easily reduced. Furthermore, when bonding to copper foil to produce a copper-clad laminate, it is preferable to adjust the CTE of the film to around 20 ppm/K to prevent peeling of the laminate film. A polymer (B) with an optimal CTE can be selected depending on the CTE of the resin to be mixed. The CTE can be measured, for example, by thermomechanical analysis (hereinafter sometimes referred to as TMA), and can be determined by the method described in the Examples.

In one embodiment of the present invention, it is preferable that at least one of the glass transition temperature and melting point of polymer (B) is 100°C or higher. The Tg of polymer (B) is preferably 100°C or higher, more preferably 140°C or higher, even more preferably 160°C or higher, even more preferably 180°C or higher, particularly preferably 200°C or higher, especially more preferably 220°C or higher, especially even more preferably 240°C or higher, and most preferably 260°C or higher, and is preferably 500°C or lower, more preferably 400°C or lower, even more preferably 350°C or lower, and even more preferably 320°C or lower. Furthermore, when polymer (B) is a crystalline polymer having a melting point, the melting point of polymer (B) is preferably 100°C or higher, more preferably 140°C or higher, even more preferably 160°C or higher, even more preferably 180°C or higher, especially preferably 200°C or higher, especially more preferably 220°C or higher, especially even more preferably 240°C or higher, and most preferably 260°C or higher, and preferably 500°C or lower, more preferably 400°C or lower, and even more preferably 350°C or lower. When at least one of the Tg and melting point of polymer (B) is above the above lower limit, the CTE of the film is easily reduced, and mechanical properties such as water absorption resistance, heat resistance, and flex resistance are easily improved. When at least one of the Tg and melting point of polymer (B) is below the above upper limit, the mechanical properties of the film, particularly repeated flex resistance, are easily improved. The Tg of polymer (B) is the softening temperature measured by TMA based on JIS K 7196, and can be measured, for example, by the method described in the Examples. The method for adjusting the Tg and melting point of polymer (B) is not particularly limited, but examples include methods of appropriately adjusting the content of monomer unit (I), Mw, crystallinity, etc. of polymer (B). The Tg and melting point of polymer (B) tend to increase as at least one selected from the group consisting of the content of monomer unit (I), Mw, and crystallinity of polymer (B) increases. The melting point of polymer (B) can be determined, for example, using a differential scanning calorimeter (DSC, manufactured by Hitachi High-Tech Science Corporation) and measuring the melting peak temperature from the resulting melting curve.

In one embodiment of the present invention, the average primary particle diameter of the particulate polymer (B) is preferably 15 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less, even more preferably 3 μm or less, particularly preferably 1 μm or less, especially more preferably 0.8 μm or less, especially more preferably 0.5 μm or less, and preferably 0.01 μm or more, more preferably 0.03 μm or more, and even more preferably 0.05 μm or more. When the average primary particle diameter of the particulate polymer (B) is equal to or greater than the above-mentioned lower limit, the mechanical properties of the film are likely to be improved. When the average primary particle diameter of the particulate polymer (B) is equal to or less than the above-mentioned upper limit, the particle dispersibility of the particulate polymer (B) is increased and the brightness is likely to be reduced, which in turn makes it easier to improve the water absorption resistance of the film and to improve mechanical properties such as the surface smoothness and flex resistance of the film. The average primary particle diameter of the particulate polymer (B) can be determined by image analysis of images taken with an electron microscope. For example, a cross-section of the film can be observed using a scanning transmission electron microscope (STEM), the particle sizes of 50 or more particles can be measured from the observed image, and the average value of these can be used as the average primary particle size of the particulate cycloolefin copolymer.

The content of the particulate polymer (B) is typically 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more, relative to the total mass of the polyimide resin (A) and the particulate polymer (B) contained in the film. It is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less. When the content of the particulate polymer (B) is above the above-mentioned lower limit, the particle dispersion in the film is likely to be improved, thereby reducing the brightness of the film and improving the water absorption resistance, surface smoothness, and mechanical properties. When the content of the particulate polymer (B) is below the above-mentioned upper limit, the brightness of the film is likely to be reduced and the formability is likely to be improved. Furthermore, high particle dispersion in the film increases the uniformity of the thermal conductivity and CTE, which, for example, helps to prevent peeling between the film and copper foil when the film is used as a resin layer in a CCL.

<Method for producing polymer (B)>
The polymer (B) may be a commercially available product or may be produced by a conventional method. In one embodiment of the present invention, the polymer (B) is preferably a cycloolefin-based polymer. The method for producing the cycloolefin-based polymer is not particularly limited. For example, the cycloolefin-based polymer is preferably produced by polymerizing a monomer that forms the cycloolefin-based polymer, such as the cycloolefin represented by formula (I), at least one monomer selected from the group consisting of ethylene, linear α-olefins having 3 to 20 carbon atoms, and aromatic vinyl compounds having 8 to 20 carbon atoms, and optionally the other monomers, in the presence of a catalyst containing a transition metal complex (α) represented by formula (IV) as one component. In the production of the cycloolefin-based polymer of the present invention, the transition metal complex (α) represented by formula (IV) is used, which makes it easy to significantly increase the content of the monomer unit (I) in the cycloolefin-based polymer and to adjust the Tg within the above range.

[In formula (IV), M represents a transition metal element of Group 4 of the periodic table of the elements,
Cp represents a group having a cyclopentadienyl skeleton;
A represents an atom of Group 16 of the Periodic Table of Elements;
T represents an atom of Group 14 of the Periodic Table of the Elements;
^D1 and ^D2 represent a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, or a di-substituted amino group having 2 to 20 carbon atoms, and they may be the same or different.
R ¹ to R ⁶ each represent a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a di-substituted amino group having 2 to 20 carbon atoms, or a silyl group having 1 to 20 carbon atoms, which may be the same or different, and which may be optionally bonded to form a ring.]

M is a transition metal element of Group 4 of the Periodic Table of the Elements (IUPAC Inorganic Nomenclature Revised Edition 1989), such as a titanium atom, a zirconium atom, or a hafnium atom.

Cp is a group having a cyclopentadienyl skeleton, such as cyclopentadienyl, substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyl, and substituted fluorenyl. Specific examples include cyclopentadienyl, methylcyclopentadienyl, tetramethylcyclopentadienyl, n-propylcyclopentadienyl, n-butylcyclopentadienyl, isobutylcyclopentadienyl, phenylcyclopentadienyl, indenyl, methylindenyl, n-propylindenyl, n-butylindenyl, isobutylindenyl, phenylindenyl, fluorenyl, methylfluorenyl, n-propylfluorenyl, phenylfluorenyl, and dimethylfluorenyl. Among these, preferred are cyclopentadienyl groups, methylcyclopentadienyl groups, tetramethylcyclopentadienyl groups, n-butylcyclopentadienyl groups, isobutylcyclopentadienyl groups, indenyl groups, methylindenyl groups, and fluorenyl groups.

A is an atom of Group 16 of the periodic table of elements, such as an oxygen atom or a sulfur atom. Of these, an oxygen atom is preferred.

T is an atom of Group 14 of the periodic table of elements, such as a carbon atom, a silicon atom, or a germanium atom. Of these, a carbon atom or a silicon atom is preferred.

D ¹ and D ² are each independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, or a di-substituted amino group having 2 to 20 carbon atoms, and may be the same or different. Among these, a halogen atom is preferred.

Specific examples of when D ¹ and D ² are halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

When D ¹ and D ² are hydrocarbon groups, the number of carbon atoms therein is preferably 1 to 10. Examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a neopentyl group, an n-hexyl group, an n-octyl group, a phenyl group, a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, a naphthyl group, and a benzyl group.

Specific examples of when D ¹ and D ² are halogenated hydrocarbon groups include a fluoromethyl group, a difluoromethyl group, a 1-fluoroethyl group, a 1,1-difluoroethyl group, a 1,2-difluoroethyl group, a 1,1,2-trifluoroethyl group, a tetrafluoroethyl group, a chloromethyl group, a dichloromethyl group, a 1-chloroethyl group, a 1,1-dichloroethyl group, a 1,2-dichloroethyl group, a 1,1,2-trichloroethyl group, a 1,1,2,2-tetrachloroethyl group, a bromomethyl group, a dibromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromomethyl group, a 1-bromoethyl ... bromoethyl group, 1,1-dibromoethyl group, 1,2-dibromoethyl group, 1,1,2-tribromoethyl group, 1,1,2,2-tetrabromoethyl group, 2-fluorophenyl group, 3-fluorophenyl group, 4-fluorophenyl group, 2,3-difluorophenyl group, 2,4-difluorophenyl group, 2,5-difluorophenyl group, 2,6-difluorophenyl group, 2,3,4-trifluorophenyl group, 2,3,5-trifluorophenyl group, 2,3,6-trifluorophenyl group, 2,3 , 4,5-tetrafluorophenyl group, 2,3,4,6-tetrafluorophenyl group, pentafluorophenyl group, 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2,3-dichlorophenyl group, 2,4-dichlorophenyl group, 2,5-dichlorophenyl group, 2,6-dichlorophenyl group, 2,3,4-trichlorophenyl group, 2,3,5-trichlorophenyl group, 2,3,6-trichlorophenyl group, 2,3,4,5-tetrachlorophenyl group, 2,3,4,6-tetrachlorophenyl group Examples thereof include a tetrachlorophenyl group, a pentachlorophenyl group, a 2-bromophenyl group, a 3-bromophenyl group, a 4-bromophenyl group, a 2,3-dibromophenyl group, a 2,4-dibromophenyl group, a 2,5-dibromophenyl group, a 2,6-dibromophenyl group, a 2,3,4-tribromophenyl group, a 2,3,5-tribromophenyl group, a 2,3,6-tribromophenyl group, a 2,3,4,5-tetrabromophenyl group, a 2,3,4,6-tetrabromophenyl group, and a pentabromophenyl group.

Specific examples of when D ¹ and D ² are alkoxy groups include methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, neopentoxy, n-hexoxy, and n-octoxy groups.

Specific examples of when D ¹ and D ² are aryloxy groups include a phenoxy group, a 2-methylphenoxy group, a 3-methylphenoxy group, a 4-methylphenoxy group, and a naphthyloxy group.

When D ¹ and D ² are disubstituted amino groups, the disubstituted amino group is an amino group having two bonded substituents, and specific examples thereof include a dimethylamino group, a diethylamino group, a di-n-propylamino group, a diisopropylamino group, a di-n-butylamino group, a diisobutylamino group, a di-sec-butylamino group, a di-tert-butylamino group, a di-n-hexylamino group, a di-n-octylamino group, and a diphenylamino group.

R ¹ to R ⁶ each independently represent a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a di-substituted amino group having 2 to 20 carbon atoms, or a silyl group having 1 to 20 carbon atoms, which may be the same or different, and which may further be optionally bonded to form a ring. Among these, a hydrocarbon group having 1 to 20 carbon atoms is preferred.

When R ¹ to R ⁶ are hydrocarbon groups, the carbon number thereof is preferably 1 to 10. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a neopentyl group, an n-hexyl group, an n-octyl group, a phenyl group, a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, a 2,3-dimethylphenyl group, a 2,4-dimethylphenyl group, a 2,5-dimethylphenyl group, a 2,6-dimethylphenyl group, a 2,3,4-trimethylphenyl group, a 2,3,5-trimethylphenyl group, a 2,3,6-trimethylphenyl group, a 2,3,4,5-tetramethylphenyl group, a 2,3,4,6-tetramethylphenyl group, and a pentamethylphenyl group.

Specific examples of when R ¹ to R ⁶ are a halogen atom, a halogenated hydrocarbon group, an alkoxy group, an aryloxy group, or a disubstituted amino group include those exemplified above as specific examples of when D ¹ and D ² are a halogen atom, a halogenated hydrocarbon group, an alkoxy group, an aryloxy group, or a disubstituted amino group.

Specific examples of when R ¹ to R ⁶ are silyl groups include a trimethylsilyl group, a triethylsilyl group, a tri-n-propylsilyl group, a triisopropylsilyl group, a tri-n-butylsilyl group, a triisobutylsilyl group, a tri-sec-butylsilyl group, a tri-tert-butylsilyl group, and a triphenylsilyl group.

Specific examples of such compounds represented by formula (IV) include isopropylidene(cyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride, isopropylidene(methylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride, isopropylidene(dimethylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride, isopropylidene(trimethylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride, isopropylidene(tetramethylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride, and isopropylidene(n-propylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride. Isopropylidene(n-butylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride, isopropylidene(isobutylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride, isopropylidene(phenylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride, isopropylidene(cyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene(methylcyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene(dimethylcyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene isopropylidene(trimethylcyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene(tetramethylcyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene(n-propylcyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene(n-butylcyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene(isobutylcyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene(phenylcyclopentadienyl)(3-tert-butyl-2-phenoxy)titanium dichloride, isopropylidene(cyclopentadienyl)(2-phenoxy)titanium dichloride Examples of the titanium dichloride include isopropylidene(methylcyclopentadienyl)(2-phenoxy)titanium dichloride, isopropylidene(dimethylcyclopentadienyl)(2-phenoxy)titanium dichloride, isopropylidene(trimethylcyclopentadienyl)(2-phenoxy)titanium dichloride, isopropylidene(tetramethylcyclopentadienyl)(2-phenoxy)titanium dichloride, isopropylidene(n-propylcyclopentadienyl)(2-phenoxy)titanium dichloride, isopropylidene(n-butylcyclopentadienyl)(2-phenoxy)titanium dichloride, isopropylidene(isobutylcyclopentadienyl)(2-phenoxy)titanium dichloride, and isopropylidene(phenylcyclopentadienyl)(2-phenoxy)titanium dichloride.

Further examples include compounds in which titanium in the above specific examples is replaced with zirconium or hafnium, as well as compounds in which isopropylidene is replaced with dimethylsilylene, diphenylsilylene, or methylene. Furthermore, compounds in which dichloride is replaced with dibromide, diiodide, dimethyl, dibenzyl, dimethoxide, or diethoxide are also examples.

The transition metal complex (α) represented by the above formula (IV) can be used in combination with various co-catalysts as a catalyst for producing polymer (B) according to one embodiment of the present invention. A co-catalyst is a compound that interacts with the transition metal complex (α) to generate species active in polymerization with cyclic olefins and alkenyl aromatic hydrocarbons. Examples include organoaluminum compounds (β) and/or boron compounds (γ) represented by any of the following formulas (γ1) to (γ3), but the structure of the active species generated by using these co-catalysts is not clear.

Formula (γ1) BQ ¹ Q ² Q ³
Formula (γ2) J ⁺ (BQ ¹ Q ² Q ³ Q ⁴ ) ⁻
Formula (γ3) (L−H) ⁺ (BQ ¹ Q ² Q ³ Q ⁴ ) ⁻
[In formulas (γ1) to (γ3), B represents a boron atom in a trivalent state,
Q ¹ to Q ⁴ each independently represent a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, a substituted silyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a disubstituted amino group having 2 to 20 carbon atoms;
J ⁺ represents an inorganic or organic cation;
L represents a neutral Lewis base, and (L-H) ⁺ represents a Bronsted acid.

The organoaluminum compound (β) can be any known organoaluminum compound. Specific examples include organoaluminum compounds represented by formula (β1), cyclic aluminoxanes having a structure represented by formula (β2), and linear aluminoxanes having a structure represented by formula (β3). These can be used alone or in combination of two or more.

Formula (β1) E ¹ _a AlZ _3-a
Formula (β2) {-Al(E ² )-O-} _b
Formula (β3) E ³ {-Al(E ³ )-O-} _c AlE ³ ₂
[In formulas (β1) to (β3), E ¹ , E ² , and E ³ each independently represent a hydrocarbon group having 1 to 8 carbon atoms, all of E ^{1 s} , all of E ^{2 s} , and all of E ^{3 s} may be the same or different, Z represents hydrogen or halogen, all of Z s may be the same or different, a represents an integer of 0 to 3, b represents an integer of 2 or greater, and c represents an integer of 1 or greater.]

Specific examples of compounds of formula (β1) include trialkylaluminums such as trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, and trihexylaluminum; dialkylaluminum chlorides such as dimethylaluminum chloride, diethylaluminum chloride, dipropylaluminum chloride, diisobutylaluminum chloride, and dihexylaluminum chloride; alkylaluminum dichlorides such as methylaluminum dichloride, ethylaluminum dichloride, propylaluminum dichloride, isobutylaluminum dichloride, and hexylaluminum dichloride; and dialkylaluminum hydrides such as dimethylaluminum hydride, diethylaluminum hydride, dipropylaluminum hydride, diisobutylaluminum hydride, and dihexylaluminum hydride. Among these, trialkylaluminums are preferred, and triethylaluminum or triisobutylaluminum is more preferred.

Specific examples of ^E2 and ^E3 in formula (β2) and formula (β3) include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, and a neopentyl group. Among these, a methyl group or an isobutyl group is preferred. b is an integer of 2 or more, preferably an integer of 2 to 40. c is an integer of 1 or more, preferably an integer of 1 to 40.

The above-mentioned aluminoxanes can be produced by various methods. There are no particular limitations on the method, and they can be produced according to known methods. Examples include a method in which a solution of trialkylaluminum, such as trimethylaluminum, dissolved in a suitable organic solvent, such as benzene or an aliphatic hydrocarbon, is brought into contact with water, and a method in which a trialkylaluminum, such as trimethylaluminum, is brought into contact with a metal salt containing water of crystallization, such as copper sulfate hydrate.

The boron compound (γ) can be any of the boron compounds represented by formula (γ1), formula (γ2), or formula (γ3).

In formula (γ1), B represents a trivalent boron atom, and Q ¹ to Q ³ each independently represent a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group having 1 to 20 carbon atoms, a substituted silyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a disubstituted amino group having 2 to 20 carbon atoms, and they may be the same or different. Q ¹ to Q ³ each independently are preferably a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogenated hydrocarbon group having 1 to 20 carbon atoms.

Specific examples of boron compounds represented by formula (γ1) include tris(pentafluorophenyl)borane, tris(2,3,5,6-tetrafluorophenyl)borane, tris(2,3,4,5-tetrafluorophenyl)borane, tris(3,4,5-trifluorophenyl)borane, tris(2,3,4-trifluorophenyl)borane, and phenylbis(pentafluorophenyl)borane, with tris(pentafluorophenyl)borane being preferred.

In formula (γ2), B represents a trivalent boron atom, Q ¹ to Q ⁴ are the same as Q ¹ to Q ³ in formula (γ1), and J ⁺ represents an inorganic or organic cation.

Examples of inorganic cations in J ⁺ include ferrocenium cations, alkyl-substituted ferrocenium cations, and silver cations.
Examples of organic cations in J ⁺ include triphenylmethyl cations.
Examples of (BQ ¹ Q ² Q ³ Q ⁴ ) ⁻ include tetrakis(pentafluorophenyl)borate anion, tetrakis(2,3,5,6-tetrafluorophenyl)borate anion, tetrakis(2,3,4,5-tetrafluorophenyl)borate anion, tetrakis(3,4,5-trifluorophenyl)borate anion, tetrakis(2,2,4-trifluorophenyl)borate anion, phenylbis(pentafluorophenyl)borate anion, and tetrakis(3,5-bistrifluoromethylphenyl)borate anion.

Specific combinations of these include ferrocenium tetrakis(pentafluorophenyl)borate, 1,1'-dimethylferrocenium tetrakis(pentafluorophenyl)borate, silver tetrakis(pentafluorophenyl)borate, triphenylmethyl tetrakis(pentafluorophenyl)borate, triphenylmethyl tetrakis(3,5-bistrifluoromethylphenyl)borate, etc., with triphenylmethyl tetrakis(pentafluorophenyl)borate being preferred.

In formula (γ3), B represents trivalent boron, Q ¹ to Q ⁴ are the same as Q ¹ to Q ³ in formula (γ1), L represents a neutral Lewis base, and (L−H) ^{2 +} represents a Bronsted acid.

In the formula (γ3), examples of the Bronsted acid (LH) ⁺ include trialkyl-substituted ammonium cation, N,N-dialkylanilinium cation, dialkylammonium cation, and triarylphosphonium cation.
(BQ ¹ Q ² Q ³ Q ⁴ ) ⁻ includes the same as those mentioned above.

Specific combinations of these include triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(3,5-bistrifluoromethylphenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, and N,N-2,4,6-pentamethylanilinium tetrakis(pentafluorophenyl)borate. Examples of suitable tetrakis(pentafluorophenyl)borate include tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(3,5-bistrifluoromethylphenyl)borate, di-iso-propylammonium tetrakis(pentafluorophenyl)borate, dicyclohexylammonium tetrakis(pentafluorophenyl)borate, triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(methylphenyl)phosphonium tetrakis(pentafluorophenyl)borate, and tri(dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate. Among these, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate or N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate is preferred.

As a co-catalyst, it is preferable to use an organoaluminum compound (β) and a compound (γ) in combination.

The transition metal complex (α) represented by formula (IV), the organoaluminum compound (β), and/or the compound (γ) can be added and used in any order during polymerization, but a reaction product obtained by previously contacting any combination of these compounds may also be used.

The molar ratio of co-catalyst to transition metal complex (α) is preferably 0.01 to 10,000, more preferably 0.5 to 2,000. When the catalyst component is used in solution, the concentration of the transition metal complex (α) is preferably 0.0001 to 5 mmol/L, more preferably 0.001 to 1 mmol/L. The amount of catalyst component used is preferably 0.00001 to 1 mol%, more preferably 0.0001 to 0.1 mol%, based on the total amount of all monomers used.

The polymerization method for polymer (B) according to one embodiment of the present invention is not particularly limited, and any method can be used, such as batch or continuous gas phase polymerization, bulk polymerization, solution polymerization using an appropriate solvent, or slurry polymerization.

When using a solvent, various solvents can be used as long as they do not deactivate the catalyst. Examples of such solvents include hydrocarbon solvents such as benzene, toluene, pentane, hexane, heptane, and cyclohexane; and halogenated hydrocarbon solvents such as dichloromethane and ethylene dichloride.

When a solvent is used, the ethylene partial pressure in the system during polymerization is, for example, 50 to 400 kPa, preferably 50 to 300 kPa, and the hydrogen partial pressure is preferably 0 to 100 kPa. When ethylene and hydrogen are introduced into the system, it is preferable to pressurize the system at the hydrogen partial pressure and then at the ethylene partial pressure. Alternatively, after the solution of the cycloolefin represented by formula (I) is introduced into the polymerization reactor, toluene may also be added.

The polymerization temperature is preferably 50°C or higher, more preferably 50 to 150°C, and even more preferably 50 to 100°C. A chain transfer agent such as hydrogen can also be added to adjust the molecular weight of the polymer.

<Polyimide Resin (A)>
The polyimide resin (A) includes a resin containing a repeating structural unit containing an imide group (hereinafter sometimes referred to as a polyimide resin), a resin containing a repeating structural unit containing both an imide group and an amide group (hereinafter sometimes referred to as a polyamideimide resin), and a precursor before the polyimide resin is produced by imidization. The precursor before the polyimide resin is produced is a polyamic acid. In this specification, the "repeating structural unit" may be referred to as a "structural unit." Furthermore, a "structural unit derived from" may be simply referred to as a "unit," for example, a structural unit derived from a compound may be referred to as a compound unit.

In a preferred embodiment of the present invention, the polyimide resin (A) is represented by the formula (1):
[In formula (1), X represents a divalent organic group, Y represents a tetravalent organic group, and * represents a bond.]
It is preferable that the polyimide resin has a structural unit represented by the following formula: Such a polyimide resin can easily reduce the CTE of the film and can easily improve the mechanical properties such as heat resistance and flex resistance.

In formula (1), X independently represents a divalent organic group, preferably a divalent organic group having 2 to 100 carbon atoms. Examples of divalent organic groups include divalent aromatic groups and divalent aliphatic groups. Examples of divalent aliphatic groups include divalent acyclic aliphatic groups and divalent cyclic aliphatic groups. Among these, divalent cyclic aliphatic groups and divalent aromatic groups are preferred, with divalent aromatic groups being more preferred, from the viewpoint of easily reducing the CTE of the film and easily improving the heat resistance and mechanical properties. The divalent organic group may have a hydrogen atom substituted with a halogen atom, a hydrocarbon group, an alkoxy group, or a halogenated hydrocarbon group. In such cases, the number of carbon atoms in these groups is preferably 1 to 8. In this specification, a divalent aromatic group refers to a divalent organic group having an aromatic group, and may include an aliphatic group or other substituent as part of its structure. Furthermore, a divalent aliphatic group is a divalent organic group that has an aliphatic group, and may contain other substituents as part of its structure, but does not include an aromatic group.

In one embodiment of the present invention, the polyimide resin (A) may contain multiple types of X, which may be the same or different. Examples of X in formula (1) include groups (structures) represented by formulas (2) to (8); and groups represented by formulas (5) to (8) in which a hydrogen atom has been substituted with a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, fluoro group, chloro group, or trifluoromethyl group.

[In formula (2) and formula (3), R ^a and R ^b each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms; a hydrogen atom contained in R ^a and R ^b may each independently be substituted with a halogen atom; W each independently represent a single bond, —O—, —CH ₂ —, —CH ₂ —CH ₂ —, —CH(CH ₃ ) —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —COO—, —OOC—, —SO ₂ —, —S—, —CO—, or —N(R ^c )—; R ^c represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a halogen atom, n represents an integer of 0 to 4, t represents an integer of 0 to 4, u represents an integer of 0 to 4, and * represents a bond.
In formula (4), ring A represents a cycloalkane having 3 to 8 carbon atoms, ^Rd represents an alkyl group having 1 to 20 carbon atoms, r represents an integer of 0 to (the number of carbon atoms in ring A minus 2) inclusive, S1 and S2 each independently represent an integer of 0 to 20, and * represents a bond.

Other examples of X in formula (1) include divalent acyclic aliphatic groups such as linear or branched alkylene groups, such as ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, propylene, 1,2-butanediyl, 1,3-butanediyl, 1,12-dodecanediyl, 2-methyl-1,2-propanediyl, and 2-methyl-1,3-propanediyl. Hydrogen atoms in the divalent acyclic aliphatic groups may be substituted with halogen atoms, and carbon atoms may be substituted with heteroatoms, such as oxygen atoms and nitrogen atoms.

Among these, from the viewpoint of easily achieving high water absorption resistance, high dielectric properties, a low CTE, high heat resistance, and high mechanical properties in the film, it is preferable that the polyimide resin (A) in the present invention contains, as X in formula (1), a structure represented by formula (2) and/or a structure represented by formula (3), and more preferably a structure represented by formula (2).

In formula (2) and formula (3), the bond of each benzene ring or cyclohexane ring may be bonded at any of the ortho, meta, or para positions, or the α, β, or γ positions relative to -W-. From the viewpoint of easily reducing the CTE of the film and easily improving water absorption resistance, heat resistance, and mechanical properties, it is preferably bonded at the meta, para, or β, or γ position, more preferably at the para or γ position. R ^a and R ^b each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 2-ethylpropyl group, and an n-hexyl group. Examples of alkoxy groups having 1 to 6 carbon atoms include methoxy, ethoxy, propyloxy, isopropyloxy, butoxy, isobutoxy, tert-butoxy, pentyloxy, hexyloxy, and cyclohexyloxy. Examples of aryl groups having 6 to 12 carbon atoms include phenyl, tolyl, xylyl, naphthyl, and biphenyl. The hydrogen atoms contained in R ^a and R ^b may each independently be substituted with a halogen atom, and examples of such halogen atoms include fluorine, chlorine, bromine, and iodine. Among these, from the viewpoints of easily reducing the CTE of the film and easily improving the water absorption resistance, heat resistance, and dielectric properties, R ^a and R ^b are preferably each independently an alkyl group having 1 to 6 carbon atoms or a fluorinated alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms or a fluorinated alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group or a trifluoromethyl group.

In formulas (2) and (3), t and u are each independently an integer from 0 to 4, and are preferably an integer from 0 to 2, more preferably 0 or 1, from the viewpoint of easily reducing the CTE of the film and easily improving the heat resistance and mechanical properties.

In formula (2) and formula (3), W each independently represents a single bond, —O—, —CH ₂ —, —CH ₂ —CH 2 —CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —COO—, —OOC—, —SO ₂ —, —S—, —CO— or —N(R ^c )—. From the viewpoint of easily reducing the CTE of the film and easily improving the water absorption resistance, heat resistance, and mechanical properties, particularly the bending resistance, W preferably represents a single bond, —O—, —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —COO—, —OOC— or —CO—, more preferably a single bond, —O—, —CH ₂ —, —C(CH ₃ ) ₂ — or —C(CF ₃ ) ₂ -. ^Rc represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 2-ethylpropyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a tert-octyl group, an n-nonyl group, and an n-decyl group, and these may be substituted with a halogen atom. Examples of the halogen atom include the same as those described above.

In formula (2) and formula (3), n is an integer of 0 to 4, and from the viewpoint of easily reducing the CTE of the film and easily improving the water absorption resistance, heat resistance, and mechanical properties, n is preferably an integer of 0 to 3, more preferably 1 or 2. When n is 2 or more, multiple Ws, R ^as , and ts may be the same or different, and the positions of the bonds of each benzene ring relative to -W- may also be the same or different.

When the polyimide resin (A) of the present invention contains both a structure represented by formula (2) and a structure represented by formula (3) as X in formula (1), W, n, R ^a , R ^b , t, and u in formula (2) may be independently the same as or different from W, n, R ^a , R ^b , t, and u in formula (3).

In formula (4), ring A represents a cycloalkane having 3 to 8 carbon atoms. Examples of cycloalkanes include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane, and preferably cycloalkanes having 4 to 6 carbon atoms. In ring A, the bonds may or may not be adjacent to each other. For example, when ring A is cyclohexane, the two bonds may be in the α-, β-, or γ-position, preferably the β- or γ-position.

^Rd in formula (4) represents an alkyl group having 1 to 20 carbon atoms. Examples of the alkyl group having 1 to 20 carbon atoms include those exemplified above as the hydrocarbon groups having 1 to 20 carbon atoms for R ⁷ to R ¹⁸ , and preferably represents an alkyl group having 1 to 10 carbon atoms. r in formula (4) represents an integer of 0 or more and (the number of carbon atoms in ring A - 2) or less. r is 0 or more and preferably 4 or less. S1 and S2 in formula (4) independently represent an integer of 0 to 20. S1 and S2 are independently preferably 0 or more, more preferably 2 or more, and preferably 15 or less.

Specific examples of the structures represented by formulas (2) to (4) include structures represented by formulas (4') and (9) to (30). In these formulas, * represents a bond.

In a preferred embodiment of the present invention, when X in formula (1) contains a structure represented by formula (2) and/or formula (3), the proportion of structural units represented by X in formula (1) represented by formula (2) and/or formula (3) is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, particularly preferably 90 mol% or more, and preferably 100 mol% or less, relative to the total molar amount of structural units represented by formula (1). When the proportion of structural units represented by X in formula (1) represented by formula (2) and/or formula (3) is within the above range, the CTE of the film is easily reduced, and the water absorption resistance, heat resistance, dielectric properties, and mechanical properties are easily improved. The proportion of structural units represented by Y in formula (1) represented by formula (2) and/or formula (3) can be measured, for example, using ^1H -NMR, or can be calculated from the charging ratio of raw materials.

In formula (1), each Y independently represents a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbon atoms, and more preferably a tetravalent organic group having 4 to 40 carbon atoms and a cyclic structure. Examples of cyclic structures include alicyclic, aromatic, and heterocyclic structures. The organic group may have a hydrogen atom substituted with a halogen atom, a hydrocarbon group, an alkoxy group, or a halogenated hydrocarbon group, and in such cases, the number of carbon atoms in these groups preferably ranges from 1 to 8. The polyimide resin (A) of the present invention may contain multiple types of Y, which may be the same or different. Examples of Y include groups (structures) represented by formulas (31) to (38); groups in which a hydrogen atom in a group represented by formulas (34) to (38) has been substituted with a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, fluoro group, chloro group, or trifluoromethyl group; and tetravalent chain hydrocarbon groups having 1 to 8 carbon atoms.

[In formulas (31) to (33), R ¹⁹ to R ²⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹⁹ to R ²⁶ each independently may be substituted with a halogen atom;
V ¹ and V ² each independently represent a single bond, —O—, —CH ₂ —, —CH ₂ —CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —COO—, —OOC—, —SO ₂ —, —S—, —CO—, —N(R ^j )—, the formula (a) or the formula (b),
(In formula (a), R ²⁷ to R ³⁰ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; Z represents —C(CH ₃ ) ₂ — or —C(CF ₃ ) ₂ —; i represents an integer of 1 to 3; and * represents a bond; R ^j represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom; e and d each independently represent an integer of 0 to 2; f represents an integer of 1 to 3; g and h each independently represent an integer of 0 to 4; and * represents a bond.)

Among these, from the viewpoint of facilitating a reduction in the CTE of the film and enhancing the heat resistance and mechanical properties, the polyimide resin of the present invention preferably contains, as Y in formula (1), at least one structure selected from the group consisting of a structure represented by formula (31), a structure represented by formula (32), or a structure represented by formula (33), and more preferably contains a structure represented by formula (31).

In formulas (31) to (33), R ¹⁹ to R ²⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the aryl group having 6 to 12 carbon atoms include those exemplified above for the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the aryl group having 6 to 12 carbon atoms in formulas (2) and (3), respectively. The hydrogen atoms contained in R ¹⁹ to R ²⁶ may each independently be substituted with a halogen atom, and examples of the halogen atom include those exemplified above. Among these, from the viewpoint of easily improving the water absorption resistance, heat resistance, and dielectric properties of the film, R ¹⁹ to R ²⁶ each independently preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and even more preferably a hydrogen atom.

In formula (31), V ¹ and V ² each independently represent a single bond, —O—, —CH ₂ —, —CH ₂ —CH 2 —CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —COO—, —OOC—, —SO ₂ —, —S—, —CO—, —N(R ^j )—, formula (a) or formula (b), and from the viewpoint of easily reducing the CTE of the film and easily improving the water absorption resistance, heat resistance and mechanical properties, preferably represent a single bond, —O—, —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —COO—, —OOC— or —CO—, more preferably a single bond, —O—, —C(CH ₃ ) ₂ — or —C(CF ₃ ) ₂ -. R ^j represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms include those exemplified above.

In formula (31), e and d each independently represent an integer from 0 to 2. From the viewpoint of easily reducing the CTE of the film and easily improving the heat resistance and mechanical properties, e and d are preferably 0 or 1, and more preferably e + d = 1.

In formula (32), f represents an integer of 1 to 3, and is preferably 1 or 2, more preferably 1, from the viewpoint of easily reducing the CTE of the film and easily improving the heat resistance and mechanical properties.

In formula (33), g and h each independently represent an integer from 0 to 4. From the viewpoint of easily reducing the CTE of the film and easily improving the heat resistance and mechanical properties, they are preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably g + h = an integer from 0 to 2.

In formula (a), R ²⁷ to R ³⁰ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include those exemplified above as the alkyl group having 1 to 6 carbon atoms in formulas (2) and (3). Among these, from the viewpoint of easily reducing the CTE of the film and easily improving the heat resistance and mechanical properties, it is more preferable that R ²⁷ to R ³⁰ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and even more preferably a hydrogen atom.

In formula (a), Z represents -C( _CH3 ) _2- or -C( _CF3 ) _2- . When Z has such a structure, the water absorption resistance, heat resistance, dielectric properties, and mechanical properties of the film are likely to be improved. i represents an integer of 1 to 3, and is preferably 1 or 2 from the viewpoint of facilitating a reduction in the CTE of the film and facilitating the improvement of the water absorption resistance, heat resistance, and mechanical properties. When i is 2 or greater, multiple Zs and ^R27 to ^R30 may be the same or different.

Specific examples of the structures represented by formulas (31) to (33) include structures represented by formulas (39) to (51). In these formulas, * represents a bond.

In one embodiment of the present invention, when Y in formula (1) contains at least one selected from the group consisting of structures represented by formulas (31) to (33), the proportion of structural units represented by Y in formula (1) selected from the group consisting of structures represented by formulas (31) to (33) is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, particularly preferably 90 mol% or more, and preferably 100 mol% or less, relative to the total molar amount of structural units represented by formula (1). When the proportion of structural units represented by Y in formula (1) selected from the group consisting of structures represented by formulas (31) to (33) is within the above range, the CTE of the film is easily reduced, and the water absorption resistance, heat resistance, dielectric properties, and mechanical properties are easily improved. The proportion of structural units represented by Y in formula (1) selected from the group consisting of structures represented by formulas (31) to (33) can be measured, for example, using ^1H -NMR, or can be calculated from the feed ratio of the raw materials.

The polyimide resin (A) of the present invention may contain, in addition to the structural unit represented by formula (1), at least one selected from the group consisting of a structural unit represented by formula (52), a structural unit represented by formula (53), and a structural unit represented by formula (54).

[In formula (52) and formula (53), Y ¹ represents a tetravalent organic group,
^Y2 represents a trivalent organic group;
^X1 and ^X2 each independently represent a divalent organic group;
* represents a bond.
In formula (54), G and X each independently represent a divalent organic group.
* represents a bond.

In a preferred embodiment of the present invention, in formulas (52) and (53), ^Y1 has the same meaning as Y in formula (1), and ^X1 and ^X2 have the same meaning as X in formula (1). ^Y2 in formula (53) is preferably a group in which any one of the bonds of Y in formula (1) has been replaced with a hydrogen atom. Examples of ^Y2 include a group in which any one of the bonds of the groups (structures) represented by formulas (31) to (38) has been replaced with a hydrogen atom; and a trivalent chain hydrocarbon group having 1 to 8 carbon atoms. In one embodiment of the present invention, the polyimide resin may contain multiple types of ^Y1 or ^Y2 , and the multiple types of ^Y1 or ^Y2 may be the same or different from one another.

In formula (54), G's each independently represent a divalent organic group, preferably a divalent organic group having 2 to 100 carbon atoms which may be substituted with a hydrocarbon group having 1 to 8 carbon atoms or a fluorine-substituted hydrocarbon group having 1 to 8 carbon atoms, more preferably a divalent organic group having 2 to 100 carbon atoms and having a cyclic structure which may be substituted with a hydrocarbon group having 1 to 8 carbon atoms or a fluorine-substituted hydrocarbon group having 1 to 8 carbon atoms. Examples of the cyclic structure include an alicyclic ring, an aromatic ring, and a heterocyclic structure. Examples of the organic group represented by G include groups represented by formulas (31) to (38) in which two non-adjacent bonds are replaced with hydrogen atoms, and divalent chain hydrocarbon groups having 6 or less carbon atoms, preferably groups represented by formulas (39) to (51) in which two non-adjacent bonds are replaced with hydrogen atoms.
X in formula (54) has the same meaning as X in formula (1), and when a polyimide-based resin contains a structural unit represented by formula (1) and a structural unit represented by formula (54), X in each structural unit may be the same or different. In one embodiment of the present invention, the polyimide-based resin may contain multiple types of X or G, and the multiple types of X or G may be the same or different from one another.

In one embodiment of the present invention, the polyimide resin (A) comprises a structural unit represented by formula (1), and optionally at least one structural unit selected from the group consisting of a structural unit represented by formula (52), a structural unit represented by formula (53), and a structural unit represented by formula (54). From the viewpoint of easily reducing the CTE of the film and easily improving the water absorption resistance, heat resistance, and dielectric properties, the proportion of the structural unit represented by formula (1) in the polyimide resin (A) is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more, based on the total molar amount of all structural units contained in the polyimide resin, for example, the structural unit represented by formula (1), and optionally at least one structural unit selected from the group consisting of the structural unit represented by formula (52), the structural unit represented by formula (53), and the structural unit represented by formula (54). The upper limit of the proportion of the structural unit represented by formula (1) in the polyimide resin (A) is 100 mol% or less. The above ratio can be measured, for example, by ¹ H-NMR, or can be calculated from the ratio of the raw materials used. The polyimide resin in the present invention is preferably a polyimide resin, from the viewpoints that the CTE of the film can be easily reduced and the water absorption resistance, heat resistance, and dielectric properties can be easily improved.

In one embodiment of the present invention, the polyimide-based resin (A) may contain a halogen atom, preferably a fluorine atom, which can be introduced, for example, by the above-mentioned halogen-containing substituent. When the polyimide-based resin (A) contains a halogen atom, preferably a fluorine atom, it is easy to improve the water absorption resistance, heat resistance, and dielectric properties, as well as the optical properties. Preferred fluorine-containing substituents for incorporating fluorine atoms into the polyimide-based resin (A) include, for example, a fluoro group and a trifluoromethyl group.

When the polyimide resin (A) contains halogen atoms, the content of halogen atoms in the polyimide resin (A) is preferably 0.1 to 40% by mass, more preferably 1 to 35% by mass, and even more preferably 5 to 30% by mass, based on the mass of the polyimide resin. When the content of halogen atoms is at or above the lower limit, the water absorption resistance, heat resistance, and dielectric properties of the film tend to be improved. When the content of halogen atoms is at or below the upper limit, the CTE of the film can be reduced and synthesis is easier.

The imidization ratio of polyimide resin (A) is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more, and is typically 100% or less. From the viewpoint of easily improving the dielectric properties, optical properties, and water absorption resistance of the film, it is preferable that the imidization ratio be equal to or greater than the above-mentioned lower limit. The imidization ratio indicates the ratio of the molar amount of imide bonds in the polyimide resin to twice the molar amount of structural units derived from tetracarboxylic acid compounds in the polyimide resin. When polyimide resin (A) contains a tricarboxylic acid compound, the imidization ratio indicates the ratio of the molar amount of imide bonds in the polyimide resin to the sum of twice the molar amount of structural units derived from tetracarboxylic acid compounds in the polyimide resin and the molar amount of structural units derived from tricarboxylic acid compounds. The imidization ratio can be determined by IR, NMR, or the like.

The Tg of polyimide resin (A) is preferably 100°C or higher, more preferably 150°C or higher, even more preferably 200°C or higher, even more preferably 300°C or higher, particularly preferably 350°C or higher, and preferably 550°C or lower. When the Tg of polyimide resin (A) is above the above lower limit, the heat resistance of the resulting film is easily improved and the CTE is easily reduced. When the Tg of polyimide resin (A) is below the above upper limit, the mechanical properties are easily improved. The Tg of polyimide resin (A) can be determined, for example, by dynamic viscoelasticity measurement (hereinafter sometimes abbreviated as DMA measurement), and can be measured by the method described in the Examples.

The Mw of the polyimide resin (A), in terms of polystyrene, is preferably 50,000 or more, more preferably 100,000 or more, more preferably 150,000 or more, even more preferably 200,000 or more, even more preferably 250,000 or more, and particularly preferably 300,000 or more, and is preferably 1,000,000 or less, more preferably 800,000 or less, even more preferably 700,000 or less, even more preferably 500,000 or less, and especially preferably 450,000 or less. When the Mw of the polyimide resin (A) is at or above the lower limit, the water absorption resistance, heat resistance, and mechanical properties of the resulting film are likely to be improved, and the CTE is likely to be reduced. When the Mw of the polyimide resin (A) is at or below the upper limit, moldability is likely to be improved. The Mw of the polyimide resin (A) can be determined, for example, by GPC measurement and standard polystyrene conversion, for example, by the method described in the Examples.

As described above, the polyimide resin (A) in the present invention includes a precursor of the polyimide resin before imidization. When the polyimide resin (A) is a polyamic acid, the polyamic acid is represented by the formula (1'):
[In formula (1′), Y and X represent Y and X in formula (1), respectively]
It contains a structural unit represented by:

<Method for producing polyimide resin (A)>
The method for producing the polyimide resin (A) is not particularly limited, but it can be produced, for example, by a method including a step of reacting a diamine compound with a tetracarboxylic acid compound to obtain a polyamic acid, and a step of imidizing the polyamic acid. When the polyimide resin (A) is a polyamic acid, the step of obtaining the polyamic acid may be carried out. In addition to the tetracarboxylic acid compound, a dicarboxylic acid compound or a tricarboxylic acid compound may also be reacted.

Tetracarboxylic acid compounds used in the synthesis of polyimide-based resin (A) include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic acid dianhydrides; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic acid dianhydrides. Tetracarboxylic acid compounds may be used alone or in combination of two or more. In addition to dianhydrides, tetracarboxylic acid compounds may also be tetracarboxylic acid compound analogs such as acid chloride compounds.

Specific examples of tetracarboxylic acid compounds include pyromellitic anhydride (hereinafter sometimes abbreviated as PMDA), 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (hereinafter sometimes abbreviated as BPADA), 1,4,5,8-naphthalenetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as BPDA), 4,4'-(hexafluoroisopropylidenediphenoxy)diphthalic anhydride, 6-Diphthalic dianhydride (hereinafter sometimes abbreviated as 6FDA), 4,4'-oxydiphthalic anhydride (hereinafter sometimes abbreviated as ODPA), 2,2',3,3'-, 2,3,3',4'- or 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3',3,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3',3,4'-diphenylethertetraanhydride tetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 3,3",4,4"-, 2,3,3",4"- or 2,2",3,3"-p-terphenyltetracarboxylic acid dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)methane dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ether 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrenetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride (hereinafter sometimes abbreviated as HPMDA), 2,3,5,6-cyclohexanetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride tetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic acid dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (hereinafter sometimes abbreviated as CBDA), norbornane-2-spiro-α'-spiro-2"-norbornane-5,5',6,6'-tetracarboxylic acid anhydride, p- Phenylenebis(trimellitate anhydride), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-(or 1,4,5,8) -) tetrachloronaphthalene-1,4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, bis(2,3 - or 3,4-dicarboxyphenyl)sulfone dianhydride. Of these, PMDA, BPDA, 6FDA, BPADA, ODPA, HPMDA, CBDA, and p-phenylenebis(trimellitate anhydride) are preferred from the viewpoint of easily reducing the CTE of the film and easily improving water absorption resistance, heat resistance, dielectric properties, and mechanical properties. These tetracarboxylic acid compounds can be used alone or in combination of two or more.

Diamine compounds used in the synthesis of polyimide resin (A) include, for example, aliphatic diamines, aromatic diamines, and mixtures thereof. In this embodiment, "aromatic diamine" refers to a diamine having an aromatic ring, which may contain an aliphatic group or other substituents as part of its structure. This aromatic ring may be a single ring or a condensed ring, and examples include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Of these, a benzene ring is preferred. Furthermore, "aliphatic diamine" refers to a diamine having an aliphatic group, which may contain other substituents as part of its structure, but does not have an aromatic ring.

Specific examples of diamine compounds include 1,4-diaminocyclohexane, 4,4'-diamino-2,2'-dimethylbiphenyl (hereinafter sometimes referred to as m-TB), 4,4'-diamino-3,3'-dimethylbiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (hereinafter sometimes referred to as TFMB), 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene (hereinafter sometimes abbreviated as 1,3-APB), 1,4-bis(4-aminophenoxy)benzene (hereinafter sometimes abbreviated as 1,4-APB), 1,3-bis(4-aminophenoxy)benzene, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane (hereinafter sometimes abbreviated as BAPP), 2,2'-dimethyl-4,4'-diamino Aminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)]biphenyl, bis[4-(3-aminophenoxy)biphenyl, bis[1-(4-aminophenoxy)]biphenyl, bis[1-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)]benzophenone, bis[4-(3-aminophenoxy)]benzophenone, 2,2-bis-[4-(4-aminophenoxy)phenyl]he Hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl]hexafluoropropane, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 4,4'-methylenedianiline, 3,3'-methylenedianiline, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3-diaminodiphenylether, 3,4'-diaminodiphenylether, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4'-diamino-p-terphenyl, 3,3 "-diamino-p-terphenyl, m-phenylenediamine, p-phenylenediamine (sometimes abbreviated as p-PDA), resorcinol-bis(3-aminophenyl)ether, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-tert-butylphenyl)ether, bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-tert-butyl)toluene, 2,4-diaminotoluene ene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, piperazine, 4,4'-diamino-2,2'-bis(trifluoromethyl)bicyclohexane, 4,4'-diaminodicyclohexylmethane, 4,4"-diamino-p-terphenyl, bis(4-aminophenyl)terephthalate, 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,4-diamino-3,5-diethyltoluene, 2,6-diamino-3,5-diethyltoluene, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-(hexafluoropropyl) propylidene)dianiline, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,2-diaminopropane, 1,2-diaminobutane, 1,3-diaminobutane, 2-methyl-1,2-diaminopropane, 2-methyl-1,3-diaminopropane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminobenzanilide, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 9,9-bis[4-(3-amino Examples of suitable amines include 4,4'-(4-aminophenoxy)phenyl]fluorene, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,5-diamino-1,3,4-oxadiazole, bis[4,4'-(4-aminophenoxy)]benzanilide, bis[4,4'-(3-aminophenoxy)]benzanilide, 2,6-diaminopyridine, and 2,5-diaminopyridine. Among these, from the viewpoints of easily reducing the CTE of the film and easily improving water absorption resistance, heat resistance, dielectric properties, and mechanical properties, preferred are 1,4-diaminocyclohexane, 4,4'-diaminodiphenyl ether, TFMB, 4,4'-methylenedianiline, 3,3'-methylenedianiline, p-PDA, BAPP, Preferred diamine compounds include 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-2,2'-bis(trifluoromethyl)bicyclohexane, m-TB, 4,4"-diamino-p-terphenyl, bis(4-aminophenyl)terephthalate, 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene, 1,3-APB, 1,4-APB, resorcinol-bis(3-aminophenyl)ether, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,4-diamino-3,5-diethyltoluene, 2,6-diamino-3,5-diethyltoluene, 4,4'-bis(3-aminophenoxy)biphenyl, and 4,4'-(hexafluoropropylidene)dianiline. These diamine compounds can be used alone or in combination.

The polyimide resin (A) may be obtained by further reacting, in addition to the tetracarboxylic acid compound used in the resin synthesis, other tetracarboxylic acids, dicarboxylic acids, tricarboxylic acids, and their anhydrides and derivatives, as long as the various physical properties of the film are not impaired.

Other tetracarboxylic acids include water adducts of the anhydrides of the above tetracarboxylic acid compounds.

Examples of dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and their analogous acid chloride compounds, acid anhydrides, etc., which may be used alone or in combination of two or more. Specific examples include dicarboxylic acid compounds of terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, chain hydrocarbons having 8 or less carbon atoms, compounds in which two benzoic acids are linked by a single bond, -O-, _-CH2- , -C( _CH3 ) _2- , -C( _CF3 ) _2- , _-SO2- , or a phenylene group, and acid chloride compounds thereof.

Examples of tricarboxylic acid compounds include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and their analogous acid chloride compounds and acid anhydrides, which may be used alone or in combination of two or more. Specific examples include 1,2,4-benzenetricarboxylic acid anhydride; 2,3,6-naphthalenetricarboxylic-2,3-anhydride; and compounds in which phthalic anhydride and benzoic acid are linked via a single bond, —O—, —CH ₂ —, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —SO ₂ —, or a phenylene group.

In producing the polyimide resin (A), the amounts of the diamine compound, tetracarboxylic acid compound, dicarboxylic acid compound and tricarboxylic acid compound used can be appropriately selected depending on the desired ratio of each structural unit of the resin.
In a preferred embodiment of the present invention, the amount of the diamine compound used is preferably 0.94 mol or more, more preferably 0.96 mol or more, even more preferably 0.98 mol or more, particularly preferably 0.99 mol or more, and is preferably 1.20 mol or less, more preferably 1.10 mol or less, even more preferably 1.05 mol or less, particularly preferably 1.02 mol or less, relative to 1 mol of the tetracarboxylic acid compound. When the amount of the diamine compound used relative to the tetracarboxylic acid compound is within the above range, the CTE of the obtained film is likely to be reduced, and the water absorption resistance, heat resistance, dielectric properties, mechanical properties, and optical properties are likely to be improved.

The reaction temperature between the diamine compound and the tetracarboxylic acid compound is not particularly limited and may be, for example, 5 to 200°C. The reaction time is also not particularly limited and may be, for example, approximately 30 minutes to 72 hours. In a preferred embodiment of the present invention, the reaction temperature is preferably 5 to 50°C, more preferably 10 to 40°C, and the reaction time is preferably 3 to 24 hours. Such a reaction temperature and reaction time tend to reduce the CTE of the resulting film and improve its water absorption resistance, heat resistance, dielectric properties, mechanical properties, and optical properties.

The reaction between the diamine compound and the tetracarboxylic acid compound is preferably carried out in a solvent. The solvent is not particularly limited as long as it does not affect the reaction, but examples include alcoholic solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; phenolic solvents such as phenol and cresol; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone (hereinafter sometimes referred to as GBL), γ-valerolactone, propylene glycol methyl ether acetate, and ethyl lactate; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ether. Examples of suitable solvents include ketone solvents such as chiral ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; alicyclic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as N,N-dimethylacetamide (hereinafter sometimes referred to as DMAc) and N,N-dimethylformamide (hereinafter sometimes referred to as DMF); sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; carbonate solvents such as ethylene carbonate and propylene carbonate; pyrrolidone solvents such as N-methylpyrrolidone (hereinafter sometimes abbreviated as NMP); and combinations thereof. Among these, phenol solvents, amide solvents, and pyrrolidone solvents are preferred from the standpoint of solubility.

The reaction between the diamine compound and the tetracarboxylic acid compound may be carried out in an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere, or under reduced pressure, as necessary. For example, it is preferable to carry out the reaction in an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere while stirring in a strictly controlled dehydrated solvent.

In the imidization process, imidization may be performed using an imidization catalyst, by heating, or a combination of these. Examples of imidization catalysts used in the imidization process include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; alicyclic amines (monocyclic) such as N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine; azabicyclo[2.2.1]heptane, azabicyclo[3.2.1]octane, azabicyclo[2.2.2]octane, and azabicyclo[2.2.1]octane. Examples of suitable imidation catalysts include alicyclic (polycyclic) amines such as [3.2.2]nonane; and aromatic amines such as pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline), 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline. In addition, it is preferable to use an acid anhydride together with the imidation catalyst in order to facilitate the imidization reaction. Examples of suitable acid anhydrides include conventional acid anhydrides used in imidization reactions, such as aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic acid anhydrides such as phthalic acid. The imidization step by heating may be carried out in a solvent in which the polyamic acid is dissolved, or in a film form as described below.

In one embodiment of the present invention, when imidizing, the reaction temperature is typically 20 to 250°C, and the reaction time is preferably 30 minutes to 24 hours, more preferably 1 to 12 hours.

The polyimide resin (A) may be isolated by separation and purification using a conventional method, for example, a separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a combination of these. In a preferred embodiment, the resin can be isolated by adding a large amount of alcohol such as methanol to a reaction solution containing the resin to precipitate the resin, followed by concentration, filtration, drying, etc.
<Film>
The film of the present invention contains a polyimide resin (A) and a particulate polymer (B). When the haze is 75% or less, the brightness is 37 or less on both sides of the film, and when the haze is greater than 75%, the brightness is 80 or less on both sides of the film, thus exhibiting excellent water absorption resistance. The film of the present invention has excellent water absorption resistance, which can enhance the dielectric properties of the film. Furthermore, the film of the present invention also has excellent surface smoothness. Therefore, the film of the present invention can possess excellent water absorption resistance, dielectric properties, and surface smoothness.

In the film of the present invention according to one embodiment of the present invention, the distance between the HSP values of the polyimide resin (A) and the polymer (B) is preferably 6 or more.
HSP is the Hansen solubility parameter (δ), which is defined by three-dimensional parameters (δD, δP, δH) and is represented by the formula (X):
δ ² = (δD) ² + (δP) ² + (δH) ² ...(X)
[In formula (X), δD represents the London dispersion force term, δP represents the molecular polarization term (dipole-dipole force term), and δH represents the hydrogen bond term]
The Hansen solubility parameters δD, δP, and δH can be calculated using HSPiP (Hansen Solubility Parameters in Practice), a program developed by the group of Dr. Hansen, who proposed the Hansen solubility parameters. Version 4.1.07, for example, can be used. The Hansen solubility parameter method is described in detail below. A target component is dissolved in a solvent with a known HSP value, and the solubility of the component in a specific solvent is evaluated. Solubility evaluation is performed by visually determining whether or not each target component has dissolved in the solvent. This is performed for multiple solvents. It is preferable to use solvents with widely varying δt values, more specifically, preferably 10 or more, more preferably 15 or more, and even more preferably 18 or more. The solubility evaluation results are then input into HSPiP to obtain the central coordinates (δd, δp, δh) of the Hansen sphere, which are used to determine the HSP of the target composition. In addition to the above-mentioned methods, the HSP may also be determined using, for example, values from the HSPiP database or literature values, or from the structural formula using HSPiP. In this specification, the value of the Hansen solubility parameter is referred to as the HSP value, and the HSP value represents the value at 25°C. The HSP value of the polyimide resin (A), the HSP value of the polymer (B), and the HSP value of the solvent may each be determined by any of the above-mentioned methods, for example, by the method described in the Examples.

The distance between the Hansen Solubility Parameters (hereinafter sometimes abbreviated as HSP) of two substances is called the HSP distance. The HSP distance (Ra) is an index that indicates the affinity between two substances, and the smaller the value, the higher the affinity between the two substances. Conversely, the larger the Ra value, the lower the affinity between the two substances, i.e., the more difficult it is for them to be compatible.
The distance between HSP values is calculated by dividing the Hansen solubility parameters δA and δB of two substances A and B by
δA=(δDA, δPA, δHA)
δB=(δDB, δPB, δHB)
Assuming that, the inter-HSP distance (Ra) is calculated by the formula (Y):
Ra=[4×(δDA-δDB) ² + (δPA-δPB) ² + (δHA-δHB) ² ] ^0.5 ...(Y)
It can be calculated as follows.
In this specification, the HSP value and the distance between HSP values are as defined above, and can be determined according to the method described above.

In a preferred embodiment of the present invention, the film of the present invention has excellent mechanical properties such as water absorption resistance, heat resistance, and flexural resistance, as well as dielectric properties, and can have a reduced CTE, even if the distance between the HSP values of the polyimide resin (A) and the polymer (B) is relatively large. Therefore, in the film of the present invention, the distance between the HSP values of the polyimide resin (A) and the polymer (B) is preferably 6.0 or more, more preferably 7.0 or more, and even more preferably 8.0 or more.
Furthermore, the distance between the HSP values of the polyimide resin (A) and the polymer (B) is preferably 30 or less, more preferably 25 or less, even more preferably 20 or less, and even more preferably 15 or less, from the viewpoint of the affinity between the resin and the polymer.

In one embodiment of the present invention, the total mass of the polyimide resin (A) and particulate polymer (B) contained in the film is preferably 40% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and preferably 100% by mass or less, relative to the mass of the film. When the total mass of the polyimide resin (A) and particulate polymer (B) contained in the film is at least the above-mentioned lower limit, the water absorption resistance, dielectric properties, and surface smoothness of the film are likely to be improved.

In a preferred embodiment of the present invention, the film of the present invention is a composite film in which the particulate polymer (B) is dispersed, preferably uniformly dispersed, in the polyimide resin (A). For example, the composite film preferably has a sea-island structure, with the polyimide resin (A) forming the sea and the particulate polymer (B) forming the islands. Such a composite film is likely to have improved mechanical properties such as water absorption resistance, heat resistance, and flex resistance, as well as dielectric properties, and is likely to have a reduced CTE. By setting the distance between the HSP values of the polyimide resin (A) and the polymer (B) to be equal to or greater than the above-mentioned lower limit, the particulate polymer (B) can be easily dispersed uniformly in the film, resulting in a film with excellent water absorption resistance.

In one embodiment of the present invention, the film of the present invention may have a low CTE. The CTE of the film can be appropriately designed to suit the application. When laminating the film with copper foil to produce a CCL, it is preferable to adjust the CTE of the film to around 20 ppm/K to prevent peeling of the laminated film. The CTE of the film can be adjusted by the CTE and mixing amounts of the polyimide resin (A) and particulate polymer (B) to be mixed. From the perspective of reducing the CTE, it is preferable to mix a particulate polymer (B) with a high Tg. The CTE can be measured by TMA, for example, by the method described in the Examples.

The water absorption resistance of the film of the present invention can be evaluated by its water absorption rate. In one embodiment of the present invention, the water absorption rate of the film of the present invention is preferably 1% or less, more preferably 0.8% or less, even more preferably 0.6% or less, even more preferably 0.5% or less, and particularly preferably 0.3% or less. When the water absorption rate of the film is below the above upper limit, it can have excellent water absorption resistance. Therefore, when the film of the present invention is used in the resin layer of a CCL, if the water absorption rate of the film is below the above upper limit, it is easy to improve the dielectric properties and suppress the dielectric loss and transmission loss. Furthermore, the water absorption rate of the film of the present invention may usually be 0.01% or more. The water absorption rate of the film of the present invention can be determined by exposing the film to water vapor for a certain period of time and measuring the mass of the film before and after exposure to water vapor, and can be measured, for example, by the method described in the Examples.

In one embodiment of the present invention, the film of the present invention can have excellent surface smoothness. The surface smoothness of a film can be evaluated by the standard deviation of the average thickness measured in ten measurement regions obtained by dividing a linear 1 mm area of the film surface into ten equal parts. In one embodiment of the present invention, the standard deviation of the average thickness of the film of the present invention is preferably 2.5 or less, more preferably 2.0 or less, even more preferably 1.70 or less, even more preferably 1.50 or less, particularly preferably 1.0 or less, especially more preferably 0.8 or less, and especially more preferably 0.5 or less. When the standard deviation of the average thickness is below the above upper limit, the surface smoothness of the film can be further improved. Therefore, when the film is used as a resin layer for a CCL, for example, high processing accuracy can be easily achieved when increasing the wiring density and miniaturization, and peeling between the film and copper foil can be easily suppressed. The lower limit of the standard deviation of the average thickness is usually 0.01 or more, preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.2 or more. If the standard deviation of the average thickness is equal to or greater than the above lower limit, adhesion is likely to be improved due to the anchor effect when the film is attached to copper foil with an adhesive or the like. The standard deviation of the average thickness of the film can be determined by arbitrarily selecting a continuous linear 1 mm area on the film surface, dividing the area into 10 equal parts to set 10 measurement areas, measuring the average thickness in each of the 10 measurement areas using a contact or non-contact film thickness meter, profilometer, surface profiler, or the like, and calculating the standard deviation of the average thickness in each of the obtained measurement areas. For example, it can be determined by the method described in the Examples. The average thickness in each measurement area may be an average calculated from multiple thicknesses measured at any point in that measurement area.

The film of the present invention may contain additives as needed. Examples of additives include antioxidants, flame retardants, crosslinking agents, surfactants, compatibilizers, imidization catalysts, weather resistance agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, anti-dripping agents, pigments, and fillers. Additives can be used alone or in combination.

In one embodiment of the present invention, even without the inclusion of a compatibilizer, the film of the present invention exhibits high particle dispersibility of the particulate polymer (B), thereby enabling the film to exhibit high water absorption resistance, low thermal conductivity variation, low CTE, high heat resistance, and excellent mechanical properties. Therefore, in the film of the present invention, the content of the compatibilizer is preferably 5 parts by mass or less, more preferably 1 part by mass or less, even more preferably 0.1 parts by mass or less, even more preferably less than 0.1 parts by mass, particularly preferably 0.05 parts by mass or less, especially more preferably 0.01 parts by mass or less, particularly more preferably 0.001 parts by mass or less, and most preferably 0 parts by mass, per 100 parts by mass of the polyimide resin (A). Furthermore, for example, when the polyimide resin (A) is a polyimide resin precursor such as polyamic acid and thermal imidization is required during film production, the content of the compatibilizer is preferably less than 0.1 parts by mass, even within the above range, from the viewpoint of preventing inhibition of imidization by the compatibilizer and deterioration of the film properties due to deterioration of the compatibilizer due to heating. The above content of the compatibilizer may be based on 100 parts by mass of the total of the polyimide resin (A) and the particulate polymer (B), instead of 100 parts by mass of the polyimide resin (A).

The thickness of the film of the present invention can be selected appropriately depending on the application, and is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, and preferably 500 μm or less, more preferably 300 μm or less, even more preferably 100 μm or less, and particularly preferably 80 μm or less. The film thickness can be measured using a thickness meter or the like, for example, by the method described in the Examples. Note that when the film of the present invention is a multilayer film, the above thickness represents the average thickness of the single layer portions.

The film of the present invention may be a single-layer film, or a multilayer film containing at least one layer made of the film of the present invention. The multilayer film may contain other layers (or other films). In such cases, all layers are collectively referred to as the film of the present invention. Examples of such other layers include functional layers. Examples of such functional layers include a primer layer, a gas barrier layer, an adhesive layer, and a protective layer. The functional layers may be used alone or in combination of two or more.

The film of the present invention may be subjected to surface treatment such as corona discharge treatment, flame treatment, plasma treatment, or ozone treatment by a method commonly used in industry.

The film according to one embodiment of the present invention has excellent water absorption resistance and dielectric properties. Therefore, it can be suitably used as a substrate material for high-frequency band printed circuit boards and antenna substrates. For example, CCL has a structure in which copper foil is laminated on both surfaces of a resin layer via an adhesive. When the film of the present invention is used as the resin layer, it has excellent water absorption resistance and low dielectric loss, thereby reducing transmission loss. When the film of the present invention is used as the resin layer, it has high surface smoothness and a reduced CTE, which effectively prevents peeling between the copper foil and the resin layer compared to conventional films. Furthermore, it has excellent mechanical properties, particularly bending resistance, making it resistant to plastic deformation and less prone to curling, and can also be used as a flexible substrate material.
The film of the present invention can also be suitably used for industrial materials such as automobile parts and electric and electronic parts; and optical materials such as lenses, prisms, optical fibers, and recording media.

[Film manufacturing method]
The method for producing the film of the present invention is not particularly limited, but may be, for example, the following steps:
(a) a composition preparation step of preparing a composition containing a polyimide-based resin (A), a particulate polymer (B), and a solvent;
The polyimide resin (A) can be produced by a method including (b) a coating step of applying the composition to a substrate to form a coating film, and (c) a film forming step of drying the applied liquid (coating film) to form a film. When thermally imidizing the polyimide resin (A), a step of completing the imidization reaction may be included.

<Composition preparation process>
The composition contains a polyimide resin (A), a particulate polymer (B), a solvent, and, if necessary, the additives. The composition may be prepared or produced by, for example, mixing the polyimide resin (A), the particulate polymer (B), a solvent, and optionally the additives. However, it is preferable to produce the composition by the following method, because it improves the dispersibility of the particulate polymer (B) in the resulting film, and when the haze is 75% or less, it is easy to adjust the brightness to 37 or less on both sides of the film, and when the haze is more than 75%, it is easy to adjust the brightness to 80 or less on both sides of the film, making it easy to obtain a film with excellent water absorption resistance.

In a preferred embodiment of the present invention, the method for producing the composition of the present invention comprises the steps of:
Step (1) of dissolving the polymer (B) in a first solvent to obtain a polymer (B) solution;
a step (2) of contacting the polymer (B) solution with a second solvent and then distilling off the first solvent to obtain a dispersion containing the particulate polymer (B) (hereinafter, sometimes referred to as a particulate polymer (B) dispersion); and a step (3) of adding a polyimide-based resin (A) to the particulate polymer (B) dispersion.
The use of such a production method can suppress the aggregation of particles of polymer (B), making it easy to reduce the particle size and improve dispersibility. As a result, it is easy to obtain a film having high water absorption resistance, surface smoothness, and high mechanical properties. Furthermore, the use of such a production method makes it easy to reduce the brightness of the obtained film.

Step (1) is a step of dissolving polymer (B) in a first solvent to obtain a polymer (B) solution. The form of polymer (B) dissolved in the first solvent is not particularly limited. The first solvent is not particularly limited as long as it can dissolve polymer (B). Examples include hydrocarbon solvents such as benzene, toluene, pentane, hexane, heptane, cyclohexane, and xylene; and halogenated hydrocarbon solvents such as dichloromethane and ethylene dichloride. Among these, hydrocarbon solvents are preferred. When the first solvent contains a hydrocarbon solvent, the solubility of polymer (B) with the first solvent is increased, making it easier to reduce the particle size of particulate polymer (B) and improve its dispersibility. As a result, a film with low brightness, high water absorption resistance, a smooth surface, high particle dispersibility, high heat resistance, high mechanical properties, and a low CTE is easily obtained (hereinafter, descriptions of effects after "as a result" may be omitted). The first solvent can be used alone or in combination of two or more types.

As described above, the first solvent is a solvent in which polymer (B) dissolves. In this specification, whether a polymer is "soluble" or "insoluble" can be evaluated according to the method described in "Evaluation of Solubility" in the Examples.

In one embodiment of the present invention, the distance between the HSP values of the first solvent and polymer (B) is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. When the distance between the HSP values is equal to or less than the above upper limit, the solubility of the first solvent and polymer (B) is increased, making it easier to reduce the particle size of the particulate polymer (B) and improve its dispersibility. The lower limit of the distance between the HSP values is usually greater than 0.

In one embodiment of the present invention, the distance between the HSP values of the first solvent and polymer (B) is preferably smaller than the interaction radius of polymer (B). This relationship facilitates the dissolution of polymer (B) in the first solvent, thereby facilitating the reduction of the particle size of particulate polymer (B) and the improvement of its dispersibility. Furthermore, as used herein, the interaction radius refers to the radius of the Hansen solubility sphere, i.e., the radius of the Hansen solubility sphere. When the Hansen solubility parameters of multiple solvents capable of dissolving a particular polymer, i.e., good solvents, are plotted in three-dimensional HSP space, the plots of the good solvents tend to converge in similar locations, i.e., at close positions, i.e., coordinates. A solute with a large interaction radius is easily soluble in many solvents, while a solute with a small interaction radius is easily soluble in a few solvents and poorly soluble in many solvents. For a specific unknown polymer, a solubility test is performed to determine whether various solvents are good or poor solvents, and the interaction radius of the polymer is calculated by inputting the results into HSPiP. Hereinafter, in this specification, "interaction radius" is as defined above and can be determined according to the above method.

In one embodiment of the present invention, the first solvent is preferably a solvent in which the polyimide resin (A) is insoluble. Such a solvent makes it easier to reduce the particle size of the particulate polymer (B) and improve its dispersibility.

In one embodiment of the present invention, the HSP value distance between the first solvent and the polyimide resin (A) is preferably 5.0 or greater, more preferably 6.0 or greater, even more preferably 7.0 or greater, even more preferably 8.0 or greater, and particularly preferably 9.0 or greater. When the HSP value distance is equal to or greater than the above-mentioned lower limit, the polyimide resin (A) is less likely to dissolve in the first solvent, which makes it easier to suppress the formation of aggregates of the particulate polymer (B). Furthermore, the particle size is more likely to be reduced, which makes it easier to improve dispersibility. Furthermore, the mechanical properties of the resulting film, such as surface smoothness, particle dispersibility, heat resistance, water absorption resistance, and flex resistance, are more likely to be improved, and the CTE is more likely to be reduced. The upper limit of the HSP value distance between the first solvent and the polyimide resin (A) is preferably 30.0 or less, more preferably 27 or less, even more preferably 25 or less, even more preferably 23 or less, and particularly preferably 21 or less. When the distance between the HSP values of the first solvent and the polyimide resin (A) is equal to or less than the above upper limit, aggregation of the particulate polymer (B) is easily suppressed, which makes it easier to improve particle dispersibility and increase the particle dispersibility of the resulting film.

In one embodiment of the present invention, the distance between the HSP values of the first solvent and the polyimide resin (A) is preferably greater than the interaction radius of the polyimide resin (A). This relationship makes it difficult for the polyimide resin (A) to dissolve in the first solvent, which makes it easier to suppress the formation of aggregates of the particulate polymer (B). Furthermore, the particle size is easily reduced, which makes it easier to improve dispersibility. Furthermore, the mechanical properties of the resulting film, such as surface smoothness, particle dispersibility, heat resistance, water absorption resistance, and flex resistance, are easily improved, and the CTE is easily reduced.

In one embodiment of the present invention, the solubility of polymer (B) in the first solvent is preferably greater than the solubility of polymer (B) in the second solvent. This relationship facilitates the production of a particulate polymer (B) with a small particle size and good dispersibility. The solubility of polymer (B) in a solvent can be measured by the following method. 1,000 mg of polymer (B) and 3 mL of solvent are added to a sample bottle and stirred at room temperature for 2 hours. The solid and liquid phases are then separated by filtration, and the mass X (mg) of the solid phase is measured after drying under reduced pressure at 80°C for 2 hours. The solubility Y (mg/mL) can then be calculated using the following formula:
Y=(1,000-X)/3
For example, when the polymer (B) corresponds to being "soluble" in the first solvent and "insoluble" in the second solvent according to the definitions in this specification, the solubility in the first solvent is obviously greater, and therefore it is not necessary to measure the solubility.

The content of polymer (B) in the polymer (B) solution is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. When the content of polymer (B) in the solution is at least the above lower limit, it is easy to prepare a composition. On the other hand, when the content of polymer (B) in the solution is at most the above upper limit, it is easy to obtain a dispersion and film with a small particle size and high dispersibility.

The method for dissolving polymer (B) in the first solvent is not particularly limited, but for example, the first solvent may be added to polymer (B), polymer (B) may be added to the first solvent, or both may be used. Furthermore, depending on the solubility of the first solvent in polymer (B), dissolution may also be achieved by heating or other methods.

Step (2) is a step in which the polymer (B) solution is contacted with a second solvent, and then the first solvent is distilled off to obtain a particulate polymer (B) dispersion.

The second solvent is not particularly limited as long as it is a solvent that can produce particulate polymer (B) upon contact with the polymer (B) solution. Examples include amide-based solvents such as DMAc and DMF; lactone-based solvents such as GBL and γ-valerolactone; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; carbonate-based solvents such as ethylene carbonate and propylene carbonate; pyrrolidone-based solvents such as N-methylpyrrolidone; and combinations thereof. Among these, at least one selected from the group consisting of amide-based solvents, lactone-based solvents, and pyrrolidone-based solvents is preferred from the viewpoint of easily suppressing aggregation of the particulate polymer (B) and having high particle dispersibility, thereby easily producing a film with low brightness, high water absorption resistance, a smooth surface, a low CTE, high heat resistance, and high mechanical properties. These solvents can be used alone or in combination. The particulate polymer (B) dispersion may also contain water, alcohol-based solvents, ketone-based solvents, acyclic ester-based solvents, ether-based solvents, etc.

In one embodiment of the present invention, the distance between the HSP values of the second solvent and polymer (B) is preferably 8.5 or greater, more preferably 9.0 or greater, even more preferably 10.0 or greater, and even more preferably 11.0 or greater. When the distance between the HSP values is equal to or greater than the above-mentioned lower limit, aggregation of polymer (B) particles is easily suppressed, and the particle size is easily reduced, which facilitates improved particle dispersibility. As a result, the brightness of the resulting film is easily reduced, and mechanical properties such as water absorption resistance, particle dispersibility, surface smoothness, heat resistance, and flex resistance are easily improved. Furthermore, the upper limit of the distance between the HSP values of the second solvent and polymer (B) is preferably 30.0 or less, more preferably 25.0 or less, and even more preferably 20.0 or less. When the distance between the HSP values of the second solvent and polymer (B) is equal to or less than the above-mentioned upper limit, aggregation of the particulate polymer (B) is easily suppressed, which facilitates improved particle dispersibility. Furthermore, the brightness of the resulting film is easily reduced, and particle dispersibility is easily improved.

In one embodiment of the present invention, the distance between the HSP values of the second solvent and polymer (B) is preferably greater than the interaction radius of polymer (B). This relationship makes it difficult for polymer (B) to dissolve in the second solvent, making it easier to reduce the particle size of the particulate polymer (B) in the particulate polymer (B) dispersion and improve its dispersibility.

In one embodiment of the present invention, the second solvent is preferably a solvent in which the polymer (B) is insoluble. Such a solvent makes it easier to suppress aggregation of the particulate polymer (B), making it easier to reduce the particle size and improve the dispersibility of the particles.

In one embodiment of the present invention, the second solvent is preferably a solvent in which the polyimide resin (A) dissolves. Such a solvent makes it easier for the particulate polymer (B) to disperse with small particle sizes in the resulting composition and film. Furthermore, the film is more likely to form a sea-island structure.

In one embodiment of the present invention, the HSP value distance between the second solvent and the polyimide resin (A) is preferably 10.0 or less, more preferably 9.5 or less, even more preferably 9.0 or less, and particularly preferably 8.5 or less, and is preferably 0.01 or more, more preferably 0.1 or more. When the HSP value distance is equal to or less than the above upper limit, the affinity between the second solvent and the polyimide resin (A) can be improved, and the particulate polymer (B) is dispersed with a small particle size in the resulting composition and film, making it easier to improve particle dispersibility.

In one embodiment of the present invention, the distance between the HSP values of the second solvent and the polyimide resin (A) is preferably smaller than the interaction radius of the polyimide resin (A). This relationship makes it easier for the polyimide resin (A) to dissolve in the second solvent, which in turn makes it easier for the particulate polymer (B) to disperse with small particle diameters in the resulting composition, thereby improving particle dispersibility.

The method for contacting the polymer (B) solution with the second solvent is not particularly limited, but examples include mixing the polymer (B) solution with the second solvent. Specific examples include adding the polymer (B) solution to the second solvent, and adding the second solvent to the polymer (B) solution. By contacting the polymer (B) and the second solvent in this manner, particulate polymer (B) with a small particle size can be precipitated or dispersed in the mixture of the second solvent and the first solvent. Note that small amounts of polyimide resin (A) or other additives may be added at any time during step (2), as long as they do not cause aggregation of the particulate polymer (B).

The amount of polymer (B) solution used to contact with the second solvent is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and particularly preferably 0.7 parts by mass or more, per 1 part by mass of the second solvent used; it is preferably 100 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 3 parts by mass or less, and particularly preferably 1.5 parts by mass or less. When the amount of polymer (B) solution used to contact with the second solvent is within the above range, aggregation of the particulate polymer (B) is easily suppressed, making it easy to reduce the particle size and improve the dispersibility of the particles.

In step (2), the polymer (B) solution is contacted with the second solvent, and then the first solvent is distilled off. Distillation of the first solvent can increase the dispersion stability of the particulate polymer (B). Distillation of the first solvent may also cause further precipitation of the polymer (B). The first solvent only needs to be at least partially distilled off or removed, and the first solvent may remain in the dispersion containing the particulate polymer (B). From the viewpoints of easily suppressing aggregation of the polymer (B) and facilitating the preparation of the dispersion, it is preferable that the first solvent partially remain or be partially contained in the dispersion of the particulate polymer (B).

In step (2), the method for distilling off the first solvent is not particularly limited, and an example is a method of distilling off the first solvent under reduced pressure using an evaporator, etc. The pressure and temperature during distillation can be selected appropriately depending on the characteristics of the first and second solvents, such as their boiling points. In this production method, the first solvent is distilled off from a mixture of the first and second solvents, so the boiling point of the first solvent is usually lower than that of the second solvent.

The content of the first solvent contained in the particulate polymer (B) dispersion obtained after distillation of the first solvent is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 60 parts by mass or less, even more preferably 45 parts by mass or less, particularly preferably 40 parts by mass or less, particularly more preferably 35 parts by mass or less, particularly more preferably 30 parts by mass or less, particularly even more preferably less than 30 parts by mass, and most preferably 25 parts by mass or less, and preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the second solvent. When the content of the first solvent is below the above-mentioned upper limit, aggregation of the particulate polymer (B) is easily suppressed, making it easy to reduce the particle size and improve the dispersibility of the particles. As a result, the brightness of the resulting film is easily reduced, and the water absorption resistance, particle dispersibility, surface smoothness, and mechanical properties are easily improved. Furthermore, when the content of the first solvent is above the above-mentioned lower limit, it is easy to prepare the dispersion. The content of the first solvent in the particulate polymer (B) dispersion can be measured by gas chromatography and calculated, for example, by the method described in the examples.

In one embodiment of the present invention, the content of the solvent contained in the particulate polymer (B) dispersion is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, relative to the mass of the dispersion, and is preferably 99.99% by mass or less, more preferably 99.9% by mass or less, even more preferably 99% by mass or less, and particularly preferably 95% by mass or less. When the solvent content is within the above range, aggregation of the particulate polymer (B) is easily suppressed, making it easy to reduce the particle size and improve the dispersibility of the particles. As a result, the water absorption resistance, particle dispersibility, surface smoothness, mechanical properties, etc. of the resulting film are easily improved.

In one embodiment of the present invention, the solvent contained in the particulate polymer (B) dispersion may contain a solvent other than the first solvent and the second solvent, as long as the effects of the present invention are not impaired. The other solvent is not particularly limited, and conventional solvents can be used. In one embodiment of the present invention, the total mass of the first solvent and the second solvent is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and preferably 100% by mass or less, based on the mass of the solvent contained in the dispersion. When the total mass of the first solvent and the second solvent is within the above range, aggregation of the particulate polymer (B) is easily suppressed, making it easy to reduce the particle size and improve the dispersibility of the particles. As a result, the water absorption resistance, particle dispersibility, surface smoothness, mechanical properties, etc. of the resulting film are easily improved.

The content of particulate polymer (B) contained in the particulate polymer (B) dispersion obtained after distilling off the first solvent is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, and is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less, relative to the mass of the particulate polymer (B) dispersion. When the content of polymer (B) is within the above range, particle dispersibility is easily improved, making it easy to reduce the brightness of the film and improve water absorption resistance, particle dispersibility, surface smoothness, and mechanical properties.

The particulate polymer (B) dispersion preferably contains particulate polymer (B) having a median diameter of 0.01 to 15 μm. The median diameter of the particulate polymer (B) is preferably 0.01 μm or more, more preferably 0.03 μm or more, even more preferably 0.05 μm or more, and preferably 15 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less, even more preferably 3 μm or less, particularly preferably 1 μm or less, especially more preferably 0.8 μm or less, and especially more preferably 0.5 μm or less. When the median diameter of the particulate polymer (B) in the dispersion is at least the above-mentioned lower limit, the dielectric properties of the film formed from the composition are easily improved, and the film is easily produced. When the median diameter of the particulate polymer (B) in the dispersion is at most the above-mentioned upper limit, the brightness of the film formed from the composition is easily reduced, and mechanical properties such as particle dispersibility, water absorption resistance, surface smoothness, and flex resistance are easily improved. The median diameter of the particulate polymer (B) in the dispersion can be determined by laser diffraction scattering particle size distribution measurement. For example, as described in the Examples, the particulate polymer (B) dispersion is diluted with a solvent to prepare a dispersion sample, and the resulting dispersion sample is measured using a laser diffraction/scattering particle size distribution analyzer (manufactured by Malvern Panalytical, model: NanoZS, refractive index: 1.70-0.20i). In this specification, the median diameter is also referred to as D50, and refers to the value at which the number of particles of the particulate polymer (B) on the smaller side is equal to the number of particles on the larger side.

Step (3) is a step of adding polyimide resin (A) to the particulate polymer (B) dispersion. In step (3), the added polyimide resin (A) may be in the form of a solid, preferably a powder, or in the form of a varnish obtained by dissolving polyimide resin (A) in a predetermined solvent, such as a second solvent. In one embodiment of the present invention, in step (3), the polyimide resin or polyamic acid may be added in the form of a solid, preferably a powder, or in the form of a varnish. When polyimide resin (A) is added in the form of a varnish, the content of polyimide resin (A) in the varnish is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, relative to the mass of the varnish, and is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. A content of polyimide resin (A) in the varnish within the above range facilitates film formation, which is advantageous from the perspective of film production.

The amount of polyimide resin (A) added in step (3) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 65% by mass or more, and preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 90% by mass or less, based on the total mass of polymer (B) and polyimide resin (A) in the particulate polymer (B) dispersion. When the content of polyimide resin (A) added in step (3) is at or above the above-mentioned lower limit, film formation is facilitated, which is advantageous from the perspective of film production. Furthermore, when the content of polyimide resin (A) added in step (3) is at or below the above-mentioned upper limit, the dispersibility of particulate polymer (B) in the dispersion and composition is likely to be improved, which tends to reduce variation in physical properties such as brightness, thermal conductivity, and thermal diffusivity of the resulting film, and also tends to improve water absorption resistance, particle dispersibility, surface smoothness, and mechanical properties.

The method for adding the polyimide resin (A) to the particulate polymer (B) dispersion is not particularly limited; the polyimide resin (A) may be added all at once, or the polyimide resin (A) may be added in multiple portions.

The composition preparation step according to one embodiment of the present invention may include steps other than steps (1) to (3), and may use a polymer or additive other than the polyimide resin (A) and the polymer (B), such as the additives exemplified above, within the scope of not impairing the effects of the present invention.
In a preferred embodiment of the present invention, the polyimide resin (A) is added to a dispersion of the particulate polymer (B), but the powder form of the polymer (B) may also be added to a varnish of the polyimide resin (A). As shown in the above step (3), the varnish of the polyimide resin (A) may be one in which the polyimide resin (A) is dissolved in a predetermined solvent, for example, a second solvent, or may be a resin solution obtained when a precursor of the polyimide resin (A) is synthesized, for example, a polyamic acid solution (a solution containing at least polyamic acid and a synthesis solvent).

The content of the particulate polymer (B) contained in the composition obtained in the composition preparation step is usually 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, particularly preferably 30% by mass or less, based on the total mass of the polyimide resin (A) and the particulate polymer (B). When the content of the particulate polymer (B) contained in the composition is above the above-mentioned lower limit, the dispersibility of the particulate polymer (B) is easily increased, so that the brightness of the obtained film is easily reduced, and the water absorption resistance, particle dispersibility, surface smoothness, and mechanical properties are easily improved. Furthermore, when the content of the particulate polymer (B) contained in the composition is below the above-mentioned upper limit, the brightness of the film is easily reduced and film formation is facilitated, which is advantageous from the viewpoint of film production. Furthermore, when the dispersibility of particles in the film is high, the uniformity of the thermal conductivity or thermal diffusivity and the CTE is high, and therefore, when the film is used as a resin layer of a CCL, for example, peeling between the film and copper foil is more easily suppressed.
In a preferred embodiment of the present invention, the polyimide resin (A) is added to a dispersion of the particulate polymer (B), but the polymer (B) in powder form may also be added to a varnish of the polyimide resin (A).

In one embodiment of the present invention, the total mass of the polyimide resin (A) and the particulate polymer (B) contained in the composition is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less. When the total mass of the polyimide resin (A) and the particulate polymer (B) contained in the composition is within the above range, the water absorption resistance, dielectric properties, and surface smoothness of the film are likely to be improved.

The content of the first solvent in the composition obtained in the composition preparation step is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 45 parts by mass or less, even more preferably 30 parts by mass or less, particularly preferably less than 30 parts by mass, especially preferably 25 parts by mass or less, and preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the second solvent. When the content of the first solvent is below the above-mentioned upper limit, aggregation of the particulate polymer (B) is easily suppressed and the particle size is easily reduced, thereby improving dispersibility. Therefore, a film having low brightness, high water absorption resistance, surface smoothness, and excellent mechanical properties is easily obtained. Furthermore, when the content of the first solvent is below the above-mentioned upper limit, the film's thermal conductivity or thermal diffusivity uniformity, surface smoothness, and mechanical properties are easily improved. Furthermore, when the content of the first solvent is above the above-mentioned lower limit, the composition is easily prepared.

The content of the solvent in the composition obtained in the composition preparation step is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less, based on the mass of the composition. A solvent content within the above range facilitates suppression of aggregation of the particulate polymer (B) and facilitates reduction of the particle size, thereby improving dispersibility. Therefore, a film having high water absorption resistance, surface smoothness, and excellent mechanical properties is likely to be obtained. Furthermore, when the solvent content is above the above lower limit, the resulting composition is easily kneaded, thereby improving film formability. When the solvent content is below the above upper limit, sedimentation or floating of the particulate polymer (B) in the resulting composition is easily suppressed, thereby improving the dispersibility of the particulate polymer (B).

The solvent contained in the composition obtained in the composition preparation step may contain a solvent other than the first solvent and the second solvent, as long as the effects of the present invention are not impaired. The other solvent is not particularly limited, and conventional solvents can be used. In one embodiment of the present invention, the total mass of the first solvent and the second solvent is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and preferably 100% by mass or less, based on the mass of the solvent contained in the composition. When the total mass of the first solvent and the second solvent is within the above range, aggregation of the particulate polymer (B) is easily suppressed, and the particle size is easily reduced, which makes it easy to improve dispersibility. Therefore, a film with high water absorption resistance, surface smoothness, and excellent mechanical properties is easily obtained.

The median diameter of the particulate polymer (B) in the composition obtained in the composition preparation step can be selected from the same range as the median diameter of the particulate polymer (B) in the dispersion liquid described above. The method for determining the median diameter of the particulate polymer (B) in the composition is not particularly limited, but it can be determined, for example, using a centrifugal sedimentation particle size distribution analyzer or an ultrasonic attenuation particle size distribution analyzer. In step (3), when the composition is formed by adding polyimide resin (A) to the particulate polymer (B) dispersion liquid in an amount that does not affect the particle size of the particulate polymer (B), the particle diameter in the dispersion liquid can also be measured and used as the particle diameter in the composition.

The composition obtained in the composition preparation step may contain the additives exemplified above, if necessary. In one embodiment of the present invention, the composition of the present invention is produced by the above-described method of the present invention, and therefore, even without the presence of a compatibilizer, the particle size of the particulate polymer (B) is small and the dispersibility is excellent. Therefore, the content of the compatibilizer in the composition of the present invention is preferably 5 parts by mass or less, more preferably 1 part by mass or less, even more preferably 0.1 parts by mass or less, even more preferably less than 0.1 parts by mass, particularly preferably 0.05 parts by mass or less, particularly preferably 0.01 parts by mass or less, especially more preferably 0.001 parts by mass or less, and most preferably 0 parts by mass, per 100 parts by mass of the polyimide resin (A). Furthermore, when the polyimide resin (A) is a polyimide resin precursor such as polyamic acid and thermal imidization is required during film production, the content of the compatibilizer is preferably less than 0.1 parts by mass within the above range, from the viewpoint of preventing the inhibition of imidization by the compatibilizer and the deterioration of film properties due to the alteration of the compatibilizer by heating. The above content of the compatibilizer may be based on 100 parts by mass of the total of the polyimide resin (A) and polymer (B) instead of 100 parts by mass of the polyimide resin (A).

(Coating process and film forming process)
The coating step is a step of applying the composition obtained in the steps (1) to (3) to a substrate to form a coating film.

In the coating process, the composition is applied to the substrate by a known coating method to form a coating film. Known coating methods include, for example, roll coating methods such as wire bar coating, reverse coating, and gravure coating, die coating, comma coating, lip coating, spin coating, screen printing coating, fountain coating, dipping, spraying, curtain coating, slot coating, and drip molding.

Examples of substrates include copper plates (including copper foil), SUS plates (including SUS foil and SUS belt), glass substrates, PET films, PEN films, other polyimide resin films, polyamide resin films, etc. Among these, from the viewpoint of excellent heat resistance, copper plates, SUS plates, glass substrates, PET films, PEN films, etc. are preferred, and from the viewpoints of adhesion to the film and cost, copper plates, SUS plates, glass substrates, PET films, etc. are more preferred.

In the film formation step, the coating film can be dried and peeled off from the substrate to form a film. In one embodiment of the present invention, when the substrate is copper foil, the coating film can be formed without peeling it off from the copper foil, and the resulting laminate in which the film is laminated on the copper foil can be used as a copper-clad laminate. In the case of peeling, a drying step in which the film is dried after peeling can be further performed. The drying temperature of the coating film can be selected appropriately depending on the heat resistance of the polyimide resin (A), etc. In one embodiment of the present invention, the drying can be performed at a temperature of 50 to 450°C, preferably 70 to 400°C, and in another embodiment of the present invention, the drying can be performed at a temperature of 50 to 350°C, preferably 70 to 300°C. In a preferred embodiment of the present invention, stepwise drying is preferred. Stepwise drying allows the composition to dry uniformly, which makes it easier to reduce the brightness of the resulting film, thereby making it easier to improve water absorption resistance. In addition, the Tg of the resulting film is improved, which makes it easier to reduce the CTE and improve mechanical properties and surface smoothness. For example, the coating may be heated at a relatively low temperature of 50 to 150°C, followed by heating at 200 to 450°C, preferably 200 to 350°C. The drying or heating time is preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours. By heating stepwise from a low temperature to a high temperature within this range, the water absorption resistance, uniformity of thermal conductivity or thermal diffusivity, optical properties, and Tg of the resulting film are likely to be improved. If necessary, the coating may be dried under an inert atmosphere such as nitrogen or argon, under vacuum or reduced pressure, and/or under ventilation.
When drying is performed in stages, the coating film may be peeled off from the substrate between the stages, and then the drying of the coating film may be continued, or the coating film (film) may be peeled off from the substrate after all the drying steps are completed.For example, the coating film may be peeled off from the substrate after the first stage of drying, and then the second stage or subsequent drying steps may be performed, or the coating film (film) may be peeled off from the substrate after all the drying steps are completed.The drying in the first stage may be preliminary drying.

If the substrate is copper foil, the film may be peeled off from the copper foil substrate by, for example, etching the copper foil with a ferric chloride solution or the like.

In one embodiment of the present invention, when the polyimide resin (A) in the composition is a polyimide resin precursor, such as a polyamic acid, and a polyimide resin is produced during film production, it is preferable to apply the composition to a substrate and then heat it to thermally imidize it. This heating allows drying to remove the solvent and thermal imidization to occur simultaneously. The drying and imidization temperatures are typically in the range of 50 to 450°C. From the perspective of easily obtaining a smooth film with excellent water absorption resistance, it is preferable to heat the composition in stages. For example, the solvent may be removed by heating at a relatively low temperature of 50 to 150°C, and then the composition may be heated in stages to a temperature in the range of 300 to 450°C. The heating time can be selected, for example, from the same range as above.

When the film of the present invention is a multilayer film, it can be produced by a multilayer film formation method such as coextrusion, extrusion lamination, thermal lamination, or dry lamination.

[Composition]
The present invention also encompasses a composition comprising a polyimide resin (A), a particulate polymer (B), and a solvent, the solvent comprising a first solvent and a second solvent, and the distance between the HSP values of the second solvent and the particulate polymer (B) is 8.5 or more. In a preferred embodiment of the present invention, the composition of the present invention is preferably the composition described in the above section [Film manufacturing method], and the polyimide resin (A), the particulate polymer (B), and the solvent contained in the composition are the same as those described in the sections [Film] and [Film manufacturing method].

The composition of the present invention comprises a polyimide resin (A), a particulate polymer (B), and a solvent, the solvent comprising a first solvent and a second solvent. Because the distance between the HSP values of the second solvent and the particulate polymer (B) is 8.5 or greater, the brightness is reduced, resulting in the formation of a film with improved water absorption resistance. The composition of the present invention can also form a film with a reduced CTE compared to conventional composite films. Furthermore, despite the high Tg of polymer (B), the composition of the present invention can form a film that exhibits excellent mechanical properties such as flex resistance. Therefore, the composition of the present invention can form a film that combines excellent mechanical properties such as water absorption resistance, surface smoothness, heat resistance, and flex resistance with a reduced CTE.

The present invention will be explained in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples. First, the measurement method will be explained.

<Brightness>
The composite films obtained in the Examples and Comparative Examples were evaluated for reflected light lightness (L ^* ) on both sides of the film using a spectrophotometer under the following conditions.
Device: CM3700A manufactured by Konica Minolta, Inc.
Light source: D light source Incident light: Irradiated at an angle of 2° from the normal direction to the film Detection mode: Reflection SCE
Target mask: LAV mask (measurement range: diameter 8 mm)
Sample measurement conditions: The film was placed at the reflection measurement position and covered with a dark box.

<Haze>
The composite films obtained in the examples and comparative examples were measured using a haze meter under the following conditions in accordance with JIS K 7136. The measured value was the average of five measurements.
Equipment: HM-150 manufactured by Murakami Color Technology Institute Co., Ltd.
Number of measurements: 5

<Norbornene (NB) Content>
The content of norbornene-derived monomer units (also referred to as "NB content") in the cycloolefin copolymers obtained in the Production Examples was measured using ¹³ C-NMR. ^{The 13} C-NMR measurement conditions were as follows:
Apparatus: Bruker AVANCE 600, 10 mm cryoprobe Measurement temperature: 135°C
Measurement method: proton decoupling method Concentration: 100 mg/mL
Number of accumulations: 1024 times Pulse width: 45 degrees Pulse repetition time: 4 seconds Chemical shift value standard: tetramethylsilane Solvent: Mixed solvent of 1,2-dichlorobenzene-d ₄ and 1,1,2,2-tetrachloroethane-d ₂ in a volume ratio of 85:15 The NB content in the cycloolefin copolymer was calculated based on the assignment described in "R. A. Wendt, G. Fink, Macromol. Chem. Phys., 2001, 202, 3490" using 1,2-dichlorobenzene (127.68 ppm) as the standard. Specifically, it was calculated from the following formula using the signal integral value I _C2,C3 (derived from the carbon atoms at positions 2 and 3 of the norbornene ring) observed at a chemical shift value of 44.0-52.0 ppm in a spectrum chart measured using ¹³ C-NMR, and the signal integral value I _C5,C6 +I _CE (derived from the carbon atoms at positions 5 and 6 of the norbornene ring and the carbon atom of the ethylene moiety) observed at a chemical shift value of 27.0-33.0 ppm.
NB content (mol%) = I _{C2, C3} / (I _{C5, C6} + I _CE ) x 100

<Hansen Solubility Parameter (HSP) and Distance Between HSP Values>
The Hansen solubility parameters (HSP) and the distance between HSP values of the cycloolefin copolymers, polyimide resins, solvents and fluoropolymers obtained in the Production Examples were determined as follows.

(Hansen Solubility Parameter (HSP) of Solvent)
The HSP values of the solvents were determined using values from the HSPiP (Ver. 4.1.07) database: δD for GBL was 18.0 MPa ^0.5 , δP for 16.6 MPa ^0.5 , and δH for 7.4 MPa ^0.5 ; δD for DMAc was 16.8 MPa ^0.5 , δP for 11.5 MPa ^0.5 , and δH for 9.4 MPa ^0.5 ; and δD for toluene was 18.0 MPa ^0.5 , δP for 1.4 MPa ^0.5 , and δH for 2.0 MPa ^0.5 .

(Cycloolefin Copolymer HSP)
The solubility of cycloolefin copolymers in various solvents was evaluated. To evaluate solubility, 10 mL of a solvent with known solubility parameters (see the HSPiP database; solvents used: methyl chloride, 1,4-dichlorobenzene, chloroform, toluene, p-xylene, GBL, DMAc, NMP, water, acetone, diiodomethane, butyl benzoate) and 0.1 g of cycloolefin copolymer were placed in a transparent container to prepare a mixed solution. The resulting mixed solution was subjected to ultrasonic treatment for a total of 6 hours. The appearance of the mixed solution after ultrasonic treatment was visually observed, and the solubility of each resin in the solvent was evaluated from the obtained observation results based on the following evaluation criteria.
(Evaluation criteria)
2: The appearance of the mixture is cloudy at room temperature and precipitates have formed, but when heated to 50°C and stirred with a stirrer for 30 minutes, the appearance of the mixture becomes transparent.
1: The mixture appears clear at room temperature.
0: The appearance of the mixture was cloudy at room temperature, and precipitates were present. Even after heating to 50°C and stirring with a stirrer for 30 minutes, the appearance of the mixture did not become transparent.

Based on the evaluation results of the solubility of the resulting cycloolefin copolymer in solvents, the HSP value was calculated using HSPiP and the Hansen dissolved sphere method described above.

(Polyimide resin HSP)
The solubility of polyimide resins in various solvents was evaluated. For the evaluation of solubility, 10 mL of a solvent with known solubility parameters (see the HSPiP database; solvents used: acetone, toluene, ethanol, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, hexane, GBL, ethyl acetate, methyl ethyl ketone, propylene glycol monomethyl ether, 1-butanol, N-methylformamide, 1-methylnaphthalene, bromobenzene, 1-methylimidazole, pyrazole, acetic acid) and 0.1 g of polyimide resin were placed in a transparent container to prepare a mixed solution. The resulting mixed solution was subjected to ultrasonic treatment for a total of 6 hours. The appearance of the mixed solution after ultrasonic treatment was visually observed, and the solubility of each resin in the solvent was evaluated from the obtained observation results based on the following evaluation criteria.
(Evaluation criteria)
1: The appearance of the mixture is cloudy.
0: The appearance of the mixture is transparent.

Based on the evaluation results of the solubility of the resulting polyimide resin in solvents, the HSP value was calculated using HSPiP and the Hansen dissolved sphere method described above.

(Fluoropolymer (PTFE) HSP)
The HSP values of PTFE were those described in the literature (Marion K. Buckley-Smith, "The Use of Solubility Parameters to Select Membrane Materials for Pervaporation of Organic Mixtures", The University of Waikato, Hamilton, New Zealand, 2006, p. 52). δD was 17.1 ^MPa , δP ^was 8.1 MPa, and δh was 1.3 ^MPa .

(Distance between HSP values)
The distance (Ra) between the HSP values of two substances was calculated according to formula (Y).

<Meso-type dipeptide chain/racemo-type dipeptide chain>
The ratio of meso-type norbornene dimers to racemo-type norbornene dimers (meso-type dimer/racemo-type dimer) in the cycloolefin copolymers obtained in the Production Examples was measured using ¹³ C-NMR under the same conditions as in the measurement of the NB content.
The meso-type di-sequence/racemo-type di-sequence of the norbornene di-sequence was calculated based on the assignments described in "R. A. Wendt, G. Fink, Macromol. Chem. Phys., 2001, 202, 3490" and "JP-A No. 2008-285656" using 1,1,2,2-tetrachloroethane (74.24 ppm) as a standard. Specifically, the meso-type two-chain structure/racemo-type two-chain structure was determined from ^{the following} formula using the signal integral value I _C5,C6 -m (derived from the carbon atoms at the 5th and 6th positions of the norbornene ring in the meso-type two-chain structure) observed at a chemical shift value of 27.5-28.4 ppm in a spectrum chart measured using 13 C-NMR, and the signal integral value I C5, _C6 -r (derived from the carbon atoms at the 5th and 6th positions of the norbornene ring in the racemo-type two-chain structure) observed at a chemical shift value of 28.4-29.6 ppm.
Meso-type two-chain/racemo-type two-chain = I _{C5, C6} -m/I _{C5, C6} -r

<Refractive index>
The refractive index of the cycloolefin copolymer obtained in each Production Example was determined by measuring under the following conditions using a sheet-like sample formed to a thickness of 100 μm using a vacuum press.
Equipment: Abbe refractometer, Type-3, manufactured by Atago Co., Ltd.
Light source wavelength: 589.3nm
Intermediate liquid: 1-bromonaphthalene Measurement temperature: 23±1°C

<Glass transition temperature>
(cycloolefin copolymer)
The Tg of the cycloolefin copolymer obtained in the Production Examples was determined by measuring the softening temperature by TMA in accordance with JIS K 7196. Specifically, a sample (thickness: 1.0 mm) obtained by molding the cycloolefin copolymer into a sheet using a vacuum press was measured under the following conditions, and the onset of displacement when the indenter sinks into the sample was taken as the softening temperature.
Apparatus: TMA/SS6200 manufactured by Hitachi High-Tech Science Co., Ltd.
Indenter diameter: 1 mm
Load: 780 mN
Temperature program: 20°C to 380°C at a rate of 5°C/min

(Polyimide resin)
The Tg of the polyimide resin obtained in the Production Examples was determined by the following measurement: Measurement was performed using a DMA Q800 manufactured by TA Instruments under the following conditions and samples to obtain a tan δ curve, which is the ratio of the loss modulus to the storage modulus, and then the Tg was calculated from the apex of the peak of the tan δ curve.
Sample: length 5-15 mm, width 5 mm
Experimental mode: DMA Multi-Frequency-Strain
Experimental mode detailed conditions:
(1) Clamp: Tension: Film
(2) Amplitude: 5 μm
(3) Frequency: 10 Hz (no fluctuations across all temperature ranges)
(4) Preload Force: 0.01N
(5) Force Track: 125N
Temperature conditions: (1) Temperature rise range: room temperature to 400°C, (2) Temperature rise rate: 5°C/min. Main collected data: (1) Storage modulus (E'), (2) Loss modulus (E"), (3) tan δ (E"/E').

<Mw and Mn of Cycloolefin Copolymer>
The polystyrene-equivalent Mw and Mn of the cycloolefin copolymers obtained in the Production Examples were measured using GPC. The GPC measurement was carried out under the following conditions, and peaks were designated by defining the baseline on the chromatogram based on the description in ISO 16014-1.

(GPC equipment and software)
Apparatus: HLC-8121GPC/HT (manufactured by Tosoh Corporation)
Measurement software: GPC-8020 model II data collection version 4.32 (manufactured by Tosoh Corporation)
Analysis software: GPC-8020 model II data analysis version 4.32 (manufactured by Tosoh Corporation)

(Measurement conditions)
GPC column: TSKgel GMH6-HT 7.8 mm ID × 300 mm (Tosoh Corporation), three columns connected together. Mobile phase: o-dichlorobenzene (Fujifilm Wako Pure Chemical Industries, Ltd., special grade) supplemented with 2,6-di-tert-butyl-4-methylphenol (hereinafter sometimes referred to as BHT) at a concentration of 0.1 w/V, i.e., 0.1 g/100 mL.
Flow rate: 1 mL/min Column oven temperature: 140°C
Autosampler temperature: 140°C
System oven temperature: 40°C
Detection: Refractive index detector (RID)
RID cell temperature: 140°C
Sample solution injection volume: 300 μL
Standard polystyrene for GPC column calibration: Standard polystyrene manufactured by Tosoh Corporation was weighed out in the combinations shown in Table 1 below, and 5 mL of orthodichlorobenzene with the same composition as the mobile phase was added for each combination, and the mixture was dissolved at room temperature for 2 hours to prepare a standard. After the column was calibrated using the obtained standard polystyrene for GPC column calibration, sample measurements were carried out as shown below.

(Sample solution preparation conditions)
Solvent: Orthodichlorobenzene (special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to which BHT was added at a concentration of 0.1 w/V, i.e., 0.1 g/100 mL was added.
Sample solution concentration: 1 mg/mL
Automatic dissolution shaker: DF-8020 (manufactured by Tosoh Corporation)
Dissolution conditions: 5 mg of sample was sealed in a 1,000 mesh SUS wire bag, the wire bag containing the sealed sample was placed in a test tube, 5 mL of orthodichlorobenzene with the same composition as the mobile phase was added, the test tube was covered with aluminum foil, the test tube was placed in the DF-8020, and stirred at a stirring speed of 60 reciprocations per minute at 140°C for 120 minutes. GPC measurement was performed on the solution after stirring.

<Mw of Polyimide Resin>
The polystyrene-equivalent Mw of the polyimide resins obtained in the Production Examples was measured by GPC under the following conditions.
GPC Measurement (1) Pretreatment Method A DMF eluent (DMF solution containing 10 mmol/L lithium bromide) was added to a sample to a concentration of 2 mg/mL, and the mixture was heated at 80°C for 30 minutes with stirring. After cooling, the mixture was filtered through a 0.45 µm membrane filter to prepare a measurement solution.
(2) Measurement Conditions Column: TSKgel SuperAWM-H x 2 + SuperAW2500 x 1 (inner diameter 6.0 mm, length 150 mm, 3 columns connected)
Eluent: DMF (10 mmol/L lithium bromide added)
Flow rate: 1.0 mL/min Detector: RI detector Column temperature: 40°C
Injection volume: 100μL
Molecular weight standard: Standard polystyrene

<Evaluation of Solubility>
The evaluation of whether the cycloolefin copolymer, PTFE, and polyimide resin were soluble in the solvents used in the Examples and Comparative Examples was carried out as follows.
First, 9.9 g of solvent was weighed into a 30 mL glass screw tube, and a magnetic stirrer was added to the tube for stirring. 0.1 g of polymer or resin was added and stirred at 24°C for 24 hours. After 24 hours of stirring, if no solids were visible and the solution was transparent, the solution was evaluated as "dissolved." On the other hand, if solids were visible or the solution was opaque, the solution was evaluated as "not dissolved."
<Particle size of particulate cycloolefin copolymer in dispersion and composition, and particle size of particulate PTFE in dispersion and composition>
The median diameters of the particulate cycloolefin copolymer in the particulate cycloolefin copolymer dispersion and the particulate PTFE in the particulate PTFE dispersion obtained in the Examples and Comparative Examples were determined by scattering particle size distribution measurement using laser diffraction.
Specifically, the dispersion obtained in each example was placed in a 3.5 mL glass cell and further diluted 1000 times with GBL or DMAc (using the same solvent as the dispersion), to obtain a dispersion sample containing a particulate cycloolefin copolymer or PTFE. The obtained dispersion sample was measured using a laser diffraction/scattering particle size distribution analyzer (manufactured by Malvern Panalytical, model: NanoZS, refractive index: 1.70-0.20i), and the median diameters of the particulate cycloolefin copolymer and particulate PTFE were determined.
As described above, in the examples and comparative examples, the polyimide resin was added to the dispersion in an amount that did not affect the particle diameters of the particulate cycloolefin copolymer and particulate PTFE to form the composition, and therefore the median diameters of the particulate cycloolefin copolymer and particulate PTFE in the dispersion were taken as the median diameters of the particulate cycloolefin copolymer and particulate PTFE in the composition.

<Thickness of composite film>
The thickness of the composite films obtained in the examples and comparative examples was measured at any five or more points on the film using a Digimatic Indicator (ID-C112XBS, manufactured by Mitutoyo Corporation), and the average value of these measurements was used as the thickness of the composite film.

<Solvent Content in Particulate Cycloolefin Copolymer Dispersion and Particulate PTFE Dispersion>
The solvent content in the particulate cycloolefin copolymer dispersion and particulate PTFE dispersion obtained in Examples and Comparative Examples was measured by gas chromatography. Specifically, the measurement was carried out under the following conditions, and the solvent content in the cycloolefin copolymer dispersion and particulate PTFE dispersion was calculated by the same inspection method.
Apparatus: Agilent 7890B gas chromatograph (Agilent Technologies, Inc.)
Column: DB-5 (Agilent Technologies)
Carrier gas: Helium Injection port temperature: 200°C
Detector temperature: 250°C
Internal standard solution: benzyl alcohol Solvent: chloroform

<CTE>
(CTE of composite film)
The CTE of the composite films obtained in the examples and comparative examples was measured by TMA. Specifically, the measurement was carried out under the following conditions, and the CTE was calculated from the temperature range of 50°C to 100°C.
Equipment: Hitachi High-Tech Science TMA/SS7100
Indenter (probe) diameter: 3.5 mm
Load: 50.0 mN
Temperature program: temperature increased from 20°C to 130°C at a rate of 5°C/min. Test piece: rectangular parallelepiped of 40mm x 10mm x 50µm

(CTE of Cycloolefin Copolymer)
The CTE of the cycloolefin copolymer was measured using TMA under the following conditions, and the CTE at 50°C to 100°C was calculated.
Equipment: Hitachi High-Tech Science TMA/SS6200
Indenter (probe) diameter: 3.5 mm Load: 38.5 mN Temperature program: temperature increased from 20°C to 130°C at a rate of 5°C/min Test piece: 10 mm x 10 mm x 1 mm rectangular parallelepiped

<Water absorption rate of composite film>
The composite films obtained in the examples and comparative examples were cut into pieces measuring 100 mm x 90 mm. The cut composite films were dried at 80°C for 3 hours, and then the mass of the composite film was measured and designated as the mass W0 before exposure to water vapor.
A cylindrical beaker with a diameter of 75 mm was prepared, and 150 g of water was placed in it. The beaker was then placed on a hot plate set to 120°C and the water was brought to a boil. While the water was boiling, the beaker was covered with a metal plate to prevent steam from escaping. After the water had sufficiently boiled, the metal plate lid was removed, and the beaker was covered with the composite film, with the side opposite to the side that had been in contact with the glass substrate during film formation being the side that came into contact with steam. The beaker was then covered with the film, and another metal plate was placed on top of that, exposing the composite film to water vapor. After 5 minutes, the composite film was removed and its mass was measured, and this was designated as the mass after water vapor exposure, W1. The water absorption (%) of the film was calculated using the following formula:
Water absorption rate (%) = (W1-W0)/W1×100

<Standard deviation of average thickness of composite film>
The standard deviation of the average thickness of the composite films obtained in the examples and comparative examples was calculated as follows.
A thickness profile (height profile) was obtained for any continuous linear 1 mm area on the surface of a film fixed to a glass substrate in close contact with the surface using a tactile surface profilometer (Dektak XTE, manufactured by Bruker Japan Co., Ltd.), with the glass substrate as the reference plane. This area was divided into 10 equal measurement areas, and the average thickness (average height) for each of the 10 measurement areas was determined. The standard deviation of the average thickness of the composite film was then calculated from the average thickness data for the 10 points in each measurement area.

<Reagent details>
Toluene manufactured by Sumitomo Chemical Co., Ltd., styrene manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 2-norbornene (hereinafter referred to as NB) manufactured by Arakawa Chemical Industries, Ltd., triisobutylaluminum (hereinafter referred to as TIBA) manufactured by Tosoh Finechem Corporation, and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate (hereinafter referred to as AB) manufactured by AGC Inc. were used for the synthesis of the cycloolefin copolymer.

The toluene was dehydrated using molecular sieves 13X (Union Showa Co., Ltd.) and activated alumina (NKHD-24, Sumitomo Chemical Co., Ltd.), and then nitrogen gas was blown in to remove dissolved oxygen.

NB was dissolved in toluene, dehydrated using molecular sieves 13X (Union Showa Co., Ltd.) and activated alumina (NKHD-24, Sumitomo Chemical Co., Ltd.), and then nitrogen gas was blown in to remove dissolved oxygen (hereafter referred to as NB solution). The NB concentration in the NB solution was measured using gas chromatography.

Isopropylidene(cyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride (hereinafter referred to as the complex) was synthesized according to the method described in JP-A-9-183809.

[Production of Cycloolefin Copolymer Solution 1]
<Production Example 1>
1,501 mL of NB solution (NB concentration: 3.00 mol/L) was added to an autoclave whose interior had been dried under reduced pressure, and the temperature was raised to 60°C. While stirring the system, the system was pressurized to an ethylene partial pressure of 100 kPa, and then 4.0 mL of a hexane solution of TIBA (concentration: 1.0 mol/L), 0.16 g of AB, and 10.0 mL of a toluene solution of the complex (concentration: 10 mmol/L) were added to initiate polymerization of ethylene and NB. During polymerization, the temperature in the system was maintained at 60°C, and ethylene was continuously supplied to maintain the pressure in the system at the initial value. Three hours after the start of polymerization, 5.0 mL of water was added to terminate the polymerization, and the solution in the autoclave was removed. 1,500 g of toluene and 100 g of magnesium sulfate were added to the removed solution and stirred, followed by the addition of 100 mL of water and stirring, and the solid was removed by filtration. The resulting liquid was added dropwise to acetone, and the precipitated powder was isolated by filtration. The isolated powder was further washed with acetone and dried under reduced pressure at 120°C for 2 hours to obtain 210.0 g of cycloolefin copolymer. The resulting cycloolefin copolymer had an NB content of 84.1 mol%, a Tg of 293°C, an Mw of 521,000, an Mw/Mn of 1.87, and a CTE of 49.4 ppm/K. The cycloolefin copolymer had a δD of 17.7 MPa ^0.5 , a δP of 2.1 MPa ^0.5 , a δH of 3.9 MPa ^0.5 , a meso-type double chain/racemo-type double chain ratio of 0.19, and a refractive index of 1.538. The synthesis conditions for Production Example 1 are shown in Table 2. This cycloolefin copolymer was dissolved in a toluene solution at a concentration of 2% by mass to obtain cycloolefin copolymer solution 1.

[Production of cycloolefin copolymer crushed powder]
<Production Example 2>
611.7 L of NB solution (NB concentration: 3.00 mol/L) was added to a reactor whose interior had been dried under reduced pressure, and the temperature was raised to 60°C. While stirring, the system was pressurized to an ethylene partial pressure of 100 kPa, and then 0.51 L of a hexane solution of TIBA (concentration: 0.6 mol/L), 40.8 L of a toluene solution of AB (concentration: 1.0 mmol/L), and 2.0 L of a toluene solution of the complex (concentration: 10 mmol/L) were added to initiate polymerization of ethylene and NB. During polymerization, the temperature in the system was maintained at 60°C, and ethylene was continuously supplied to maintain the pressure in the system at the initial value. After ethylene consumption reached 3.0 kg from the start of polymerization, 1.0 L of water was added to terminate the polymerization. 612 L of an aqueous NaOH solution (concentration: 0.1 mol/L) was added to the reactor, and the mixture was stirred for 30 minutes. The stirring was stopped, the aqueous solution was removed, and 612 L of water was added and stirred for 30 minutes. After adding another 612 L of water and stirring for 30 minutes, a solution of 942 L of toluene and 49.5 L of acetone was added to the reactor, followed by 314 L of acetone. The precipitated powder was isolated by filtration. The isolated powder was further washed with acetone and dried under reduced pressure at 120°C for 2 hours to obtain 60.0 kg of cycloolefin copolymer. The resulting cycloolefin copolymer had an NB content of 92.3 mol%, a Tg of 308°C, an Mw of 852,000, and an Mw/Mn ratio of 1.81. The cycloolefin copolymer also had a δD of 17.7 MPa ^0.5 , a δP of 2.1 MPa ^0.5 , a δH of 3.9 MPa ^0.5 , and a CTE of 44.5 ppm/K.
This cycloolefin copolymer was pulverized in a counter jet mill manufactured by Hosokawa Micron Corporation and classified using a filter to obtain a pulverized powder of cycloolefin copolymer having particles with a median diameter of 2.6 μm.

[Production of Cycloolefin Copolymer Solution 2]
<Production Example 3>
1,427 mL of NB solution (NB concentration: 3.00 mol/L) and 55.2 mL of styrene were added to an autoclave whose interior had been dried under reduced pressure, and the temperature was raised to 80°C. While stirring the system, 3.0 mL of a hexane solution of TIBA (concentration: 1.0 mol/L), 0.32 g of AB, and 15.0 mL of a toluene solution of the complex (concentration: 10 mmol/L) were added to initiate polymerization of NB and styrene. The temperature of the system was maintained at 80°C during polymerization. Two hours after the start of polymerization, 3.0 mL of water was added to terminate the polymerization, and the solution in the autoclave was removed. The resulting liquid was added dropwise to acetone, and the precipitated powder was isolated by filtration. The isolated powder was further washed with acetone and dried under reduced pressure at 150°C for 2 hours, yielding 198.3 g of cycloolefin copolymer. The obtained cycloolefin copolymer had an NB content of 96.3 mol%, Mw of 79,000, Mw/Mn of 1.83, and Tg of over 300°C. The cycloolefin copolymer also had a δD of 17.7 MPa ^0.5 , a δP of 2.1 MPa ^0.5 , and a δH of 3.9 MPa ^0.5 . The synthesis conditions for Production Example 3 are shown in Table 3. This cycloolefin copolymer was dissolved in a toluene solution at a concentration of 2 mass% to obtain cycloolefin copolymer solution 2.

[Synthesis of polyimide resin]
<Production Example 4>
A reactor equipped with a separable flask, a silica gel tube, a stirrer, and a thermometer, and an oil bath were prepared. After creating a nitrogen atmosphere in the flask using dry nitrogen, 75.52 g of 6FDA and 54.44 g of TFMB were added. While stirring at 400 rpm, 519.84 g of DMAc was added, and stirring continued until the contents of the flask became a homogeneous solution. Subsequently, stirring was continued for an additional 20 hours while adjusting the temperature inside the vessel to 20-30°C using an oil bath, allowing the reaction to produce polyamic acid. After 30 minutes, the stirring speed was changed to 100 rpm. After stirring for 20 hours, the reaction system temperature was returned to room temperature, and 649.8 g of DMAc was added to adjust the polymer concentration to 10% by mass. Furthermore, 32.27 g of pyridine and 41.65 g of acetic anhydride were added, and the mixture was stirred at room temperature for 10 hours to perform imidization. The polyimide varnish was removed from the reaction vessel. The resulting polyimide varnish was dropped into methanol to cause reprecipitation, and the resulting powder was dried by heating to remove the solvent, yielding a polyimide resin as a solid. The resulting polyimide resin had a δD of 18.1 MPa ^0.5 , a δP of 8.3 MPa ^0.5 , and a δH of 9.3 MPa ^0.5 . The polyimide resin also had an Mw of 334,300 and a Tg of 361°C.

[Synthesis of Polyamic Acid]
<Production Example 5>
A reactor equipped with a separable flask, a silica gel tube, a stirrer, and a thermometer, and an oil bath were prepared. 27.83 g of BPDA, 13.76 g of PMDA, and 34.00 g of m-TB were placed in the flask. While stirring at 400 rpm, 428.35 g of DMAc was added, and stirring was continued until the contents of the flask became a uniform solution. Subsequently, stirring was continued for an additional 3 hours while adjusting the temperature inside the container to a range of 20 to 30°C using an oil bath, and a polyamic acid solution was obtained in a solvent-dispersed state by the reaction.

Example 1
100.0 g of the cycloolefin copolymer solution 1 obtained in Production Example 1 and 98.0 g of GBL were mixed, and the toluene was distilled off under reduced pressure at 50 hPa and 80° C. so that the toluene content was 7 parts by mass relative to 100 parts by mass of GBL, thereby obtaining a particulate cycloolefin copolymer dispersion.
To 32.1 g of the resulting dispersion (1.9 mass % cycloolefin copolymer), 1.9 g of the polyimide resin obtained above was added to obtain a polyimide-cycloolefin copolymer mixed solution, resulting in a composition. The median diameter of the particulate cycloolefin copolymer in the dispersion and composition, measured by the above method, was 0.15 μm. No cycloolefin copolymer aggregates exceeding 1 mm were observed in the resulting composition.
The resulting composition was cast onto a glass substrate by drip molding at a linear speed of 0.4 m/min to form a coating film. The coating film was heated at 70°C for 60 minutes, and after peeling the film from the glass substrate, the film was fixed in a metal frame and further heated at 200°C for 1 hour to obtain a 60 μm-thick polyimide-cycloolefin copolymer composite film. The content of the particulate cycloolefin copolymer in the resulting composite film was 24 mass% relative to the total mass of the polyimide resin and the particulate cycloolefin copolymer. The CTE of the resulting composite film was 44 ppm/K. Furthermore, the standard deviation of the average thickness of the resulting composite film was 0.4, and the film surface smoothness was also excellent. The haze of the resulting composite film was 44.8%.
The distance between the HSP values of the cycloolefin copolymer and the polyimide resin used in Example 1 was 8.3, the distance between the HSP values of the cycloolefin copolymer and toluene was 2.1, the distance between the HSP values of the polyimide resin and toluene was 10.0, the distance between the HSP values of the cycloolefin copolymer and GBL was 14.9, and the distance between the HSP values of the polyimide resin and GBL was 8.5.
According to the above solubility evaluation method, the cycloolefin copolymer used in Example 1 was dissolved in toluene but not in GBL. The polyimide resin was dissolved in GBL but not in toluene.

Example 2
A particulate cycloolefin copolymer dispersion was obtained in the same manner as in Example 1, except that toluene was distilled off under reduced pressure at 50 hPa and 80°C so that the toluene content was 20 parts by mass relative to 100 parts by mass of GBL, and a particulate cycloolefin copolymer dispersion was obtained.
To 35.9 g of the obtained particulate cycloolefin copolymer dispersion (1.7 mass % cycloolefin copolymer), 1.9 g of the polyimide resin obtained above was added to obtain a polyimide-cycloolefin copolymer mixed solution, thereby obtaining a composition. The median diameter of the particulate cycloolefin copolymer in the dispersion and composition, measured by the above method, was 0.14 μm. No cycloolefin copolymer aggregates exceeding 1 mm were observed in the obtained composition.
A polyimide-cycloolefin copolymer composite film having a thickness of 60 μm was obtained in the same manner as in Example 1, except that the obtained composition was used. The content of the particulate cycloolefin copolymer in the obtained composite film was 24 mass% based on the total mass of the polyimide resin and the particulate cycloolefin copolymer. The CTE of the obtained composite film was 44 ppm/K. The standard deviation of the average thickness of the obtained composite film was 0.37, and the film surface smoothness was also excellent. The haze of the obtained composite film was 50.5%.

Example 3
A particulate cycloolefin copolymer dispersion was obtained in the same manner as in Example 1, except that toluene was distilled off under reduced pressure at 50 hPa and 80°C so that the toluene content was 30 parts by mass relative to 100 parts by mass of GBL, and a particulate cycloolefin copolymer dispersion was obtained.
To 38.8 g of the obtained particulate cycloolefin copolymer dispersion (1.5 mass % cycloolefin copolymer), 1.9 g of the polyimide resin obtained above was added to obtain a polyimide-cycloolefin copolymer mixed solution, thereby obtaining a composition. The median diameter of the particulate cycloolefin copolymer in the dispersion and composition, measured by the above method, was 0.13 μm. No cycloolefin copolymer aggregates exceeding 1 mm were observed in the obtained composition.
A polyimide-cycloolefin copolymer composite film having a thickness of 60 μm was obtained in the same manner as in Example 1, except that the obtained composition was used. The content of the particulate cycloolefin copolymer in the obtained composite film was 24 mass% based on the total mass of the polyimide resin and the particulate cycloolefin copolymer. The CTE of the obtained composite film was 45 ppm/K, and the film surface smoothness was also excellent. The haze of the obtained composite film was 65.7%.

Example 4
2.73 g of the cycloolefin copolymer crushed powder and 52.03 g of DMAc were mixed and stirred to obtain a dispersion liquid, the toluene content of which was 1.3 parts by mass relative to 100 parts by mass of DMAc.
To the obtained dispersion, 100 g of a polyamic acid solution (15% by mass of polyamic acid) was added to obtain a composition as a polyamic acid-cycloolefin copolymer mixed solution. The median diameter of the particulate cycloolefin copolymer in the dispersion and composition, measured by the above method, was 2.6 μm. No cycloolefin copolymer aggregates exceeding 1 mm were observed in the obtained composition.
The resulting composition was cast onto a glass substrate at a linear speed of 0.4 m/min to form a coating film. The coating film was heated at 50°C for 80 minutes, and the polyamic acid-cycloolefin copolymer composite film was peeled off from the glass substrate. The film was then fixed in a metal frame and further heated at 360°C for 15 minutes under a nitrogen atmosphere to imidize the polyamic acid, yielding a 50 μm-thick polyimide-cycloolefin copolymer composite film. The resulting film contained 15.4 mass% of the particulate cycloolefin copolymer relative to the total mass of the polyimide resin and the particulate cycloolefin copolymer. The resulting composite film had a CTE of 19 ppm/K and excellent surface smoothness. The haze of the resulting composite film was 98.9%.
The distance between the HSP values of the cycloolefin copolymer and polyamic acid used in Example 4 was 6.0 or more, and the distance between the HSP values of the cycloolefin copolymer and DMAc was 11.5. Furthermore, the distance between the HSP values of the cycloolefin copolymer used in Example 4 and the polyimide resin obtained by imidizing the polyamic acid was 6.0 or more.
According to the above-mentioned solubility evaluation method, the cycloolefin copolymer used in Example 4 was dissolved in toluene but not in DMAc, and the polyamic acid was dissolved in DMAc but not in toluene.

Example 5
5.69 g of particulate PTFE (manufactured by Polysciences Inc., melting point: 320°C, Mw: 20,000), 41.9 g of DMAc, and 0.2 g of toluene were mixed and stirred to obtain a dispersion. The toluene content of the obtained dispersion was 0.5 parts by mass per 100 parts by mass of DMAc.
100 g of polyamic acid solution (15% by mass of polyamic acid) was added to the obtained dispersion to obtain a composition as a polyamic acid-PTFE mixed solution. The median diameter of the particulate PTFE in the dispersion and composition measured by the above method was 3 μm. No PTFE aggregates exceeding 1 mm were observed in the obtained composition.
The resulting composition was applied to a glass substrate by drip casting at a linear speed of 0.4 m/min to form a coating film. The coating film was heated at 50°C for 80 minutes, and the polyamic acid-PTFE composite film was peeled off from the glass substrate. The film was then fixed in a metal frame and heated stepwise to 360°C over 30 minutes under a nitrogen atmosphere. The polyamic acid was imidized, resulting in a 50 μm-thick polyimide-PTFE composite film. The resulting film contained 27.5% by mass of particulate PTFE relative to the total mass of the polyimide resin and PTFE. The resulting composite film had a CTE of 17 ppm/K and excellent surface smoothness. The haze of the resulting composite film was 88.0%.
The distance between the HSP values of the PTFE and polyamic acid used in Example 5 was 6.0 or more, and the distance between the HSP values of the PTFE and DMAc was 9.5. The distance between the HSP values of the PTFE and polyimide resin obtained by imidizing the polyamic acid used in Example 5 was also 6.0 or more.
According to the above solubility evaluation method, the PTFE used in Example 5 was not dissolved in DMAc. Furthermore, the polyamic acid was dissolved in DMAc but not in toluene.

[Example 6]
100.0 g of the obtained cycloolefin copolymer solution 2 and 98.0 g of DMAc were mixed, and the toluene was distilled off under reduced pressure at 50 hPa and 80° C. for 2 hours to distill off the toluene so that the toluene content was 0.6 parts by mass per 100 parts by mass of DMAc, thereby obtaining a particulate cycloolefin copolymer dispersion. The median diameter of the particulate cycloolefin copolymer in the particulate cycloolefin copolymer dispersion measured by the above method was 0.13 μm.
To 10.92 g of the obtained particulate cycloolefin copolymer dispersion (particulate cycloolefin copolymer 2.0 mass%) was added 8.0 g of the polyamic acid solution to obtain a polyamic acid-cycloolefin copolymer mixed solution composition. In the obtained composition, no cycloolefin copolymer aggregates exceeding 1 mm were observed.
The resulting composition was applied to a glass substrate by drip casting at a linear speed of 0.4 m/min to form a coating film. The coating film was heated at 70°C for 60 minutes, and the polyamic acid-cycloolefin copolymer composite film was peeled off from the glass substrate. The film was then fixed in place with a metal frame and heated stepwise over 30 minutes to 360°C under a nitrogen atmosphere. This imidized the polyamic acid, resulting in a 30 μm-thick polyimide-cycloolefin copolymer composite film. The resulting film contained 15.4 mass% of the particulate cycloolefin copolymer relative to the total mass of the polyimide resin and the particulate cycloolefin copolymer. The resulting composite film had a CTE of 18 ppm/K and excellent surface smoothness. The haze of the resulting composite film was 96.6%.
The distance between the HSP values of the cycloolefin copolymer and polyamic acid used in Example 6 was 6.0 or more, the distance between the HSP values of the cycloolefin copolymer and toluene was 2.1, and the distance between the HSP values of the cycloolefin copolymer and DMAc was 11.5. Furthermore, the distance between the HSP values of the cycloolefin copolymer used in Example 6 and the polyimide resin obtained by imidizing the polyamic acid was 6.0 or more.
According to the above-mentioned solubility evaluation method, the cycloolefin copolymer used in Example 6 was dissolved in toluene but not in DMAc. The polyamic acid used in Example 6 was dissolved in DMAc but not in toluene.

Comparative Example 1
A particulate cycloolefin copolymer dispersion was obtained in the same manner as in Example 1, except that toluene was distilled off under reduced pressure at 50 hPa and 80°C so that the toluene content was 40 parts by mass per 100 parts by mass of GBL to obtain a particulate cycloolefin copolymer dispersion. The median diameter of the particulate cycloolefin copolymer in the dispersion and composition measured by the above method was 0.13 μm.
To 41.8 g of the resulting dispersion (1.4 mass % cycloolefin copolymer), 1.9 g of the polyimide resin obtained above was added to obtain a polyimide-cycloolefin copolymer mixed solution composition. No cycloolefin copolymer aggregates exceeding 1 mm were observed in the resulting composition.
A polyimide-cycloolefin copolymer composite film having a thickness of 60 μm was obtained in the same manner as in Example 1, except that the obtained composition was used. The content of the particulate cycloolefin copolymer in the obtained composite film was 24 mass% based on the total mass of the polyimide resin and the particulate cycloolefin copolymer. The CTE of the obtained composite film was 44 ppm/K. The standard deviation of the average thickness of the obtained composite film was 1.77. The haze of the obtained composite film was 69.3%.

The haze, brightness, and water absorption of the polyimide-cycloolefin copolymer composite films and polyimide-PTFE composite films obtained in the Examples and Comparative Examples were measured using the methods described above. The results are shown in Table 4. The brightness of the composite film was measured on both sides of the film, with the brightness of the side that was in contact with the glass substrate during film formation being indicated as L1, and the brightness of the opposite side being indicated as L2. Table 4 also shows the toluene content per 100 parts by mass of GBL or DMAc in the particulate cycloolefin copolymer dispersion and particulate PTFE dispersion in the Examples and Comparative Examples.

As shown in Table 4, the films obtained in Examples 1 to 6 had low water absorption rates and were superior in water absorption resistance compared to Comparative Example 1.

Claims (8)

A film comprising a polyimide-based resin (A) and a particulate polymer (B), wherein the film has a haze of 75% or less and a lightness L ^* of reflected light measured by a specular reflection elimination method of 37 or less on both surfaces of the film ;
The polyimide resin (A) is represented by the formula (1):
[In formula (1), X represents a divalent organic group, Y represents a tetravalent organic group, and * represents a bond.]
It has a constitutional unit represented by
The particulate polymer (B) has an average primary particle diameter of 3 μm or less . A film comprising a polyimide-based resin (A) and a particulate polymer (B), wherein the film has a haze of more than 75% and a lightness L ^* of reflected light measured by a specular reflection excluding method of 80 or less on both surfaces of the film ;
The polyimide resin (A) is represented by the formula (1):
[In formula (1), X represents a divalent organic group, Y represents a tetravalent organic group, and * represents a bond.]
It has a constitutional unit represented by
The particulate polymer (B) has an average primary particle diameter of 3 μm or less . The film according to claim 1 or 2, wherein the distance between the HSP values of the polyimide resin (A) and the polymer (B) is 6 or greater. 4. The film according to claim 1 , wherein the content of the particulate polymer (B) is 5 to 50% by mass based on the total mass of the polyimide resin (A) and the particulate polymer (B). The film according to any one of claims 1 to 4, wherein the polymer (B) is at least one polymer selected from the group consisting of an olefin-based polymer, a polyimide-based polymer, a fluorine-based polymer, a silicone-based polymer, a liquid crystal polymer, an aramid polymer, a styrene-based polymer, and an ether -based polymer. The film according to any one of claims 1 to 5 , wherein the polymer (B) is a cycloolefin-based polymer. 7. The film according to claim 1, wherein at least one of the glass transition temperature and the melting point of the polymer (B) is 100° C. or higher. The cycloolefin-based polymer has the formula (I):
[In formula (I), m represents an integer of 0 or greater; R ⁷ to R ¹⁸ each independently represent a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms; when a plurality of R ¹¹ to R ¹⁴ are present, they may be the same or different; and R ¹⁶ and R ¹⁷ may be bonded to each other to form a ring together with the carbon atoms to which they are bonded.]
The film according to claim 6 or 7 , comprising a cycloolefin-derived monomer unit (1) represented by the following formula: