JP7742737B2 - Laminated Film - Google Patents

Description

The present invention relates to a laminated film having a base layer and a surface layer. Specifically, the laminated film is suitable as a release film for use in the manufacturing processes of electronic products, building materials, automotive parts, and fiber-reinforced composites. Even more particularly, the present invention relates to a laminated film suitable for use as a release film for molding fiber-reinforced composites, which is placed between the interior of a mold when molding a prepreg of the fiber-reinforced composite inside the mold; a release film for semiconductor or LED element encapsulation processes, which is placed between a semiconductor chip or LED element and the inner surface of a mold when the semiconductor chip or LED element is placed inside the mold and resin is injected into the mold; and a release film for manufacturing printed wiring boards for fixing and wiring electronic components.

When molding fiber-reinforced resin, prepregs are generally used, which are reinforcing fibers such as carbon fiber or glass fiber impregnated with resin. These prepregs are then heated and molded into the desired shape.

Printed wiring boards for fixing and wiring electronic components include rigid boards, flexible printed boards, and rigid-flexible boards. In particular, the production of flexible printed boards (hereinafter also referred to as "FPCs") typically involves a process of laminating a coverlay film onto a board on which a circuit pattern has been formed, and a heat-press molding process in which the resulting laminate is sandwiched between heat-press plates and heated and pressurized.

Semiconductor chips are typically used as semiconductor resin packages encapsulated with an encapsulant. Semiconductor resin packages are generally obtained by transfer molding, in which the semiconductor chip is loaded into a mold cavity and the cavity is filled with an encapsulant whose main component is epoxy resin. Conventional transfer molding has presented problems, such as the encapsulant sometimes contaminating the inner surface of the mold, reducing work efficiency, damaging the inner surface of the mold and shortening the mold's lifespan, and easily producing burrs on the molded semiconductor resin package.

In this case, to address the above-mentioned issues, release films made of fluorine-based polymer films such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and polyvinyl fluoride, as well as polymethylpentene films, polybutylene terephthalate, and syndiotactic polystyrene are used (Patent Document 1).

In particular, it has been proposed to use a film made of poly-4-methyl-1-pentene resin as a release film, due to its excellent heat resistance, releasability after heating and pressurization, and conformability to the circuit board. Because poly-4-methyl-1-pentene has a high melting point of 235°C, a release film has been disclosed that has excellent heat resistance, releasability, and contamination resistance, even when used in the molding of copper-clad laminates, which is carried out at temperatures of around 180°C (Patent Document 2).

Other known films include a protective film made of a 4-methyl-1-pentene polymer and an olefin elastomer (Patent Document 3), and a film formed from a composition of a 4-methylpentene polymer and an olefin elastomer (Patent Document 4).

On the other hand, to improve the elastic modulus of 4-methyl-1-pentene polymer films at high temperatures, a laminated release film has been proposed in which crystalline polymethylpentene layers are formed on both the inner and outer surfaces, with an intermediate layer made of polyamide or polyester (Patent Document 5), and a laminated release film in which a flexible intermediate layer is used to provide conformability to molded articles with irregularities (Patent Document 6). However, there was a need to achieve a better balance between heat resistance and flexibility.

Japanese Patent Application Laid-Open No. 2005-350601 JP 2016-98257 A International Publication No. 2015/012274 International Publication No. 2013/099876 Japanese Patent Application Laid-Open No. 2020-142474 JP 2014-121830 A

Release films are now required to have higher levels of conformability to uneven surfaces and releasability, but the above-mentioned conventional release films have not been able to meet these requirements.
The present invention has been made in view of the above circumstances and aims to solve the above problems. That is, the present invention aims to obtain a laminated film suitable for a release film that has excellent conformability and releasability even at high temperatures of 200°C or higher, and has a low interlayer adhesion strength and a low linear expansion coefficient.

In light of the above-mentioned problems, the inventors conducted extensive research and discovered that the above-mentioned problems could be solved by a laminate film having a substrate layer made of a specific resin composition, leading to the completion of the present invention.

An example of a specific means for solving the above problem is as follows.
[1]
It comprises a substrate layer (X) and a surface layer (Y),
the base layer (X) is an olefin polymer composition (M) containing 5 to 100 parts by mass of a 4-methyl-1-pentene copolymer (A-1) satisfying the following requirements (a) to (e), and 95 to 0 parts by mass of at least one olefin polymer (B) selected from an ethylene polymer (D), a propylene polymer (C), and a butene polymer (E) (wherein the total of the components (A-1) and (B) is taken as 100 parts by mass),
A laminated film characterized in that the surface layer (Y) contains at least one thermoplastic resin selected from the group consisting of 4-methyl-1-pentene (co)polymer, polybutylene terephthalate, and polyethylene fluoride:
[4-methyl-1-pentene copolymer (A-1)]
(a) 97 to 60 mol % of structural units derived from 4-methyl-1-pentene and 3 to 40 mol % of structural units derived from at least one selected from ethylene or an α-olefin having 3 to 4 carbon atoms (wherein the total amount of structural units derived from 4-methyl-1-pentene and structural units derived from ethylene or an α-olefin having 3 to 4 carbon atoms is 100 mol %),
(b) Intrinsic viscosity [η] measured in decalin at 135 ° C. is in the range of 0.5 to 5.0 dl / g;
(c) The melting point (Tm) measured by DSC is 199°C or less, or is substantially unobservable;
(d) the molecular weight distribution (Mw/Mn), which is the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), measured by gel permeation chromatography (GPC), is in the range of 1.0 to 3.5, and (e) the density is in the range of 825 to 860 kg/ ^m3 .

[2]
2. The laminated film according to claim 1, wherein the thermoplastic resin is a 4-methyl-1-pentene (co)polymer (A-2) that satisfies the following requirements (g) to (i):
[4-methyl-1-pentene (co)polymer (A-2)]
(g) 100 to 90 mol % of structural units derived from 4-methyl-1-pentene and 0 to 10 mol % of structural units derived from at least one selected from α-olefins having 10 to 20 carbon atoms (excluding 4-methyl-1-pentene) (wherein the total amount of structural units derived from 4-methyl-1-pentene and structural units derived from α-olefins having 10 to 20 carbon atoms is 100 mol %),
(h) a melting point (Tm) measured by DSC in the range of 200-250°C, and (i) a density in the range of 820-850 kg/ ^m3 .

[3]
The laminated film according to item [1] or [2], wherein the olefin resin (B) constituting the olefin polymer composition (M) is a propylene polymer (C).

[4]
Item 4. The laminate film according to item [3], wherein the propylene polymer (C) contains 70 to 100 mol % of structural units derived from propylene and 30 to 0 mol % of structural units derived from at least one selected from ethylene or an α-olefin having 4 to 20 carbon atoms (wherein the total amount of structural units derived from propylene and structural units derived from ethylene or an α-olefin having 4 to 20 carbon atoms is taken as 100 mol %).

[5]
The laminate film according to any one of items [1] to [4], wherein the laminate film has a three or more layer structure consisting of a surface layer (Y), a base layer (X), and a surface layer (Y) in this order.

[6]
The laminate film according to any one of items [1] to [5], wherein the laminate film is a laminate film obtained by a T-die film forming method.

[7]
A release film for producing a fiber-reinforced composite material, comprising the laminate film according to any one of items [1] to [6].

[8]
A release film for producing a flexible printed circuit board, comprising the laminate film according to any one of items [1] to [6].

[9]
A release film for semiconductor production comprising the laminate film according to any one of items [1] to [6].

In the laminate film of the present invention, the base layer (X) contains a specific 4-methyl-1-pentene copolymer (A-1). The relaxation properties of the base layer reduce the linear expansion coefficient of the entire laminate film, making the film less susceptible to wrinkling and poor appearance. Furthermore, the base layer (X) can exhibit conformability to irregularities while maintaining the releasability of the surface layer (Y).

In addition, a laminate film in which the surface layer (Y) contains one or more of a specific 4-methyl-1-pentene (co)polymer (A-2), polybutylene terephthalate, and polyethylene fluoride can have good releasability and can suppress interlayer delamination between the surface layer (Y) and the substrate layer (X).

Furthermore, the laminated film of the present invention suppresses the migration of impurities to the surface of molded products and does not contain halogen-based resins, so it also has the advantages of being highly recyclable and having a low environmental impact.

Specific embodiments of the present invention are described in detail below, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the invention.

The release film according to the present invention consists of at least two layers: a substrate layer (X) and a surface layer (Y).

<Base material layer (X)>
The substrate layer (X) constituting the laminate film of the present invention comprises the following 4-methyl-1-pentene copolymer (A-1) alone, or an olefin polymer composition (M) comprising the 4-methyl-1-pentene copolymer (A-1) and an olefin polymer (B) selected from an ethylene polymer (D), a propylene polymer (C), and a butene polymer (E).

The 4-methyl-1-pentene copolymer (A-1), olefin polymer (B), and olefin polymer composition (M) that form the substrate layer (X) are each described below.

[4-methyl-1-pentene copolymer (A-1)]
4-methyl-1-pentene copolymer (A-1) (hereinafter, also referred to as "copolymer (A-1)"), which is another component forming the base layer (X) of the laminated film of the present invention, is a copolymer of 4-methyl-1-pentene and an α-olefin that satisfies the following requirements (a) to (e):

<Requirement (a)>
The content of structural units derived from 4-methyl-1-pentene is 97 to 60 mol%, preferably 90 to 60 mol%, and more preferably 88 to 70 mol%, and the content of structural units derived from at least one selected from ethylene or an α-olefin having 3 to 4 carbon atoms is 3 to 40 mol%, preferably 10 to 40 mol%, and more preferably 12 to 30 mol% (wherein the total amount of structural units derived from 4-methyl-1-pentene and structural units derived from ethylene or an α-olefin having 3 to 4 carbon atoms is 100 mol%).

<Requirement (b)>
The intrinsic viscosity [η] measured in decalin at 135° C. is in the range of 0.5 to 5.0 dl/g, preferably 0.7 to 4.0 dl/g, and more preferably 1.0 to 3.0 dl/g.

<Requirement (c)>
The melting point (Tm) measured by DSC is 199° C. or lower, preferably 180° C. or lower, more preferably 160° C. or lower, and particularly preferably 140° C. or lower, or is not substantially observable.

<Requirement (d)>
The molecular weight distribution (Mw/Mn), which is the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) measured by gel permeation chromatography (GPC), is in the range of 1.0 to 3.5, preferably 1.5 to 3.0.

<Requirement (e)>
The density is in the range of 825 to 860 kg/m ³ , preferably 830 to 850 kg/m ³ , and more preferably 833 to 845 kg/m ³ .

A laminated film containing the above-mentioned 4-methyl-1-pentene copolymer (A-1) in the substrate layer (X) can improve film formability, improve film tear strength, impart unevenness-following ability due to flexibility, and reduce the linear expansion coefficient.
The 4-methyl-1-pentene·α-olefin copolymer (A-1) preferably satisfies the following requirement (f) in addition to the above requirements (a) to (e).

<Requirement (f)>
The melt flow rate (MFR) of the 4-methyl-1-pentene/α-olefin copolymer (A-1) (measured according to ASTM D1238 at a temperature of 230°C and a load of 2.16 kgf) is preferably 4.0 to 30 g/10 min, more preferably 5.0 to 15 g/10 min, and even more preferably 7.0 to 13 g/10 min.

[Olefin polymer (B)]
The olefin polymer (B), which is one of the components constituting the olefin polymer composition (M) forming the base layer (X) constituting the laminate film of the present invention, is an olefin polymer selected from the group consisting of a propylene polymer (C), an ethylene polymer (D), and a butene polymer (E).

The olefin polymer (B) according to the present invention may be a propylene polymer (C), an ethylene polymer (D), or a butene polymer (E) alone, or a composition (mixture) of two or more of these.

[Propylene-based polymer (C)]
The propylene polymer (C), which is one of the olefin polymers (B) that are components of the olefin polymer composition (M) that forms the base layer (X) constituting the laminate film of the present invention, is a propylene homopolymer or a copolymer of propylene and ethylene or a copolymer having 4 to 20 carbon atoms, preferably ethylene or a copolymer having 4 to 8 carbon atoms. The monomer copolymerized with propylene may be a single monomer or two or more monomers.

The propylene polymer (C) according to the present invention typically contains 70 to 100 mol %, preferably 80 to 99 mol %, and more preferably 92 to 99 mol % of units derived from propylene (provided that the total amount of units derived from propylene and units derived from α-olefins (including ethylene) is 100 mol %).

The propylene polymer (C) according to the present invention usually has a density in the ^range of 860 to 920 kg/m, preferably 870 to 910 kg/ ^m , and more preferably 880 to 910 kg/ ^m , and an MFR measured in accordance with ASTM D1238 (measured at 230°C under a load of 2.16 kgf) in the range of 0.1 to 100 g/10 min, preferably 0.5 to 50 g/10 min, and more preferably 1.0 to 20 g/10 min.

The propylene polymer (C) according to the present invention typically has a melting point in the range of 60 to 165°C, preferably 70 to 160°C, more preferably 70 to 140°C, and particularly preferably 90 to 130°C. For applications requiring greater flexibility, the melting point can be preferably in the range of 60 to 130°C, more preferably 70 to 120°C. Furthermore, for applications requiring a higher tensile modulus, the melting point can be preferably in the range of 130 to 175°C, more preferably 135 to 170°C.

When the propylene polymer (C) according to the present invention is used as one component of the olefin polymer composition (M) described below, a single propylene polymer may be used, or two or more propylene polymers may be used. Furthermore, when two or more propylene polymers (C) are used, the polymers may have different physical properties.

[Ethylene-based polymer (D)]
The ethylene polymer (D), which is one of the olefin polymers (B) that constitute the olefin polymer composition (M) that forms the base layer (X) constituting the laminate film of the present invention, is a homopolymer of ethylene or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.

The ethylene polymer (C) according to the present invention typically contains 70 to 100 mol %, preferably 80 to 99 mol %, and more preferably 92 to 99 mol % of units derived from ethylene (provided that the total amount of units derived from ethylene and units derived from α-olefins (including ethylene) is 100 mol %).

The ethylene polymer (D) according to the present invention usually has a density in the range ^of 850 to 960 kg/m, preferably 850 to 930 kg/ ^m , more preferably 850 to 900 kg/ ^m , and an MFR (measured in accordance with ASTM D1238 at 190°C under a load of 2.16 kgf) in the range of 0.1 to 100 g/10 min, preferably 0.2 to 80 g/10 min, more preferably 0.5 to 20 g/10 min.

When the ethylene polymer (D) according to the present invention is used as one of the components of the olefin polymer composition (M), a single ethylene polymer may be used, or two or more ethylene polymers may be used. Furthermore, when two or more ethylene polymers (D) are used, the ethylene polymers may have different physical properties.

[Butene polymer (E)]
The butene polymer (E), which is one of the olefin polymers (B) that are components of the olefin polymer composition (M) that forms the base layer (X) constituting the laminate film of the present invention, is a homopolymer of 1-butene or a copolymer of 1-butene with one or more α-olefins selected from ethylene, propylene, and α-olefins having 5 to 20 carbon atoms.

The butene polymer (E) according to the present invention typically contains 70 to 100 mol %, preferably 80 to 99 mol %, and more preferably 92 to 99 mol % of units derived from 1-butene (provided that the total amount of units derived from 1-butene and units derived from an α-olefin (including ethylene) is 100 mol %).

The butene polymer (E) according to the present invention usually has a density in the range of 850 to 960 kg/ ^m , preferably 850 to 930 kg/ ^m , more preferably 850 to 900 kg/ ^m , and an MFR (measured in accordance with ASTM D1238 at 190°C under a load of 2.16 kgf) in the range of 0.1 to 100 g/10 min, preferably 0.2 to 80 g/10 min, more preferably 0.5 to 20 g/10 min.

When the butene polymer (E) according to the present invention is used as one component of the olefin polymer composition (M) described below, a single butene polymer may be used, or two or more different butene polymers may be used. Furthermore, when two or more different butene polymers (E) are used, they may have different physical properties.

[Olefin polymer composition (M)]
The olefin polymer composition (M) constituting the base layer (X) of the laminated film of the present invention is a composition containing 5 to 100 parts by mass, preferably 20 to 100 parts by mass, of the 4-methyl-1-pentene copolymer (A-1) and 0 to 95 parts by mass, preferably 0 to 80 parts by mass, of the olefin polymer (B) (wherein the total of components (A) and (B) is taken as 100 parts by mass).

The olefin polymer composition (M) constituting the base layer (X) of the present invention can be made into a base layer (X) that has excellent adhesion (interlayer peel strength) with the surface layer (Y) described below, or can have a reduced linear expansion coefficient, by containing the 4-methyl-1-pentene copolymer (A-1) alone or in a predetermined amount.

The olefin polymer (B) such as the propylene polymer (C) or the ethylene polymer (D) contained in the olefin polymer composition (M) is a component necessary for the base layer (X) according to the present invention to maintain the elastic modulus, flexibility, and irregularity-conforming ability required for a film. In particular, by using a propylene polymer having a density in the range of 870 to 905 kg/ ^m3 as the propylene polymer (C), a laminated film having an even better balance between flexibility and irregularity-conforming ability can be obtained.

In addition to the above-mentioned components (A-1) and (B), other resins or polymers and/or resin additives can be optionally added to the olefin polymer composition (M) of the present invention depending on the intended use, as long as the effects of the present invention are not impaired.

Such resin additives include, for example, pigments, dyes, fillers, lubricants, plasticizers, release agents, antioxidants, flame retardants, UV absorbers, antibacterial agents, surfactants, antistatic agents, weather stabilizers, heat stabilizers, antislip agents, antiblocking agents, foaming agents, crystallization aids, antifogging agents, (transparency) nucleating agents, antioxidants, hydrochloric acid absorbers, impact modifiers, crosslinking agents, co-crosslinking agents, crosslinking aids, adhesives, softeners, and processing aids. These additives can be used alone or in appropriate combinations of two or more.

Other resins or polymers that can be added include polystyrene, acrylic resin, polyphenylene sulfide resin, polyether ether ketone resin, polyester resin, polysulfone, polyphenylene oxide, polyimide, polyetherimide, acrylonitrile-butadiene-styrene copolymer (ABS), ethylene-α-olefin copolymer rubber, conjugated diene rubber, phenolic resin, melamine resin, polyester resin, silicone resin, and epoxy resin. The amount of these resins or polymers added is preferably 0.1 to 30% by mass of the total mass of the olefin polymer composition (M).

Pigments include inorganic pigments (titanium oxide, iron oxide, chromium oxide, cadmium sulfide, etc.) and organic pigments (azo lakes, thioindigo, phthalocyanines, anthraquinones). Dyes include azos, anthraquinones, triphenylmethanes, etc. The amount of these pigments and dyes added is not particularly limited, but is typically 5% by weight or less, preferably 0.1 to 3% by weight, in total, based on the total weight of the olefin polymer composition (M).

Fillers include glass fiber, carbon fiber, silica fiber, metal (stainless steel, aluminum, titanium, copper, etc.) fibers, carbon black, silica, glass beads, silicates (calcium silicate, talc, clay, etc.), metal oxides (iron oxide, titanium oxide, alumina, etc.), metal carbonates (calcium sulfate, barium sulfate), various metal (magnesium, silicon, aluminum, titanium, copper, etc.) powders, mica, glass flakes, etc. These fillers may be used alone or in combination of two or more.

Lubricants include waxes (such as carnauba wax), higher fatty acids (such as stearic acid), higher alcohols (such as stearyl alcohol), and higher fatty acid amides (such as stearic acid amide).

Plasticizers include aromatic carboxylic acid esters (such as dibutyl phthalate), aliphatic carboxylic acid esters (such as methyl acetylricinoleate), aliphatic dialkoxy esters (such as adipic acid-propylene glycol polyester), aliphatic tricarboxylic acid esters (such as triethyl citrate), phosphate triesters (such as triphenyl phosphate), epoxy fatty acid esters (such as epoxybutyl stearate), and petroleum resins.

Mold release agents include lower (C1-4) alcohol esters of higher fatty acids (such as butyl stearate), polyhydric alcohol esters of fatty acids (C4-30) (such as hydrogenated castor oil), glycol esters of fatty acids, and liquid paraffin.

Examples of antioxidants include phenol-based (such as 2,6-di-t-butyl-4-methylphenol), polycyclic phenol-based (such as 2,2'-methylenebis(4-methyl-6-t-butylphenol)), phosphorus-based (such as tetrakis(2,4-di-t-butylphenyl)-4,4-biphenylenediphosphonate), and amine-based (such as N,N-diisopropyl-p-phenylenediamine) antioxidants.

Flame retardants include organic flame retardants (nitrogen-containing, sulfur-containing, silicon-containing, phosphorus-containing, etc.) and inorganic flame retardants (antimony trioxide, magnesium hydroxide, zinc borate, red phosphorus, etc.).

Examples of ultraviolet absorbers include benzotriazole-based, benzophenone-based, salicylic acid-based, and acrylate-based ones.
Examples of antibacterial agents include quaternary ammonium salts, pyridine compounds, organic acids, organic acid esters, halogenated phenols, and organic iodines.

Surfactants include nonionic, anionic, cationic, and amphoteric surfactants. Nonionic surfactants include polyethylene glycol-type nonionic surfactants such as higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, higher alkylamine ethylene oxide adducts, and polypropylene glycol ethylene oxide adducts; polyhydric alcohol-type nonionic surfactants such as polyethylene oxide, glycerin fatty acid esters, pentaerythritol fatty acid esters, sorbitol or sorbitan fatty acid esters, polyhydric alcohol alkyl ethers, and alkanolamine fatty amides. Anionic surfactants include sulfate ester salts such as alkali metal salts of higher fatty acids; sulfonates such as alkylbenzene sulfonates, alkyl sulfonates, and paraffin sulfonates; and phosphate ester salts such as higher alcohol phosphate ester salts. Cationic surfactants include quaternary ammonium salts such as alkyltrimethylammonium salts. Amphoteric surfactants include amino acid-type amphoteric surfactants such as higher alkylaminopropionates; and betaine-type amphoteric surfactants such as higher alkyldimethylbetaines and higher alkyldimethylhydroxyethylbetaines.

Antistatic agents include the above-mentioned surfactants, fatty acid esters, and polymeric antistatic agents. Fatty acid esters include esters of stearic acid and oleic acid, and polymeric antistatic agents include polyether ester amides.

The amounts of the various additives, such as the fillers, lubricants, plasticizers, release agents, antioxidants, flame retardants, UV absorbers, antibacterial agents, surfactants, and antistatic agents, added may vary depending on the intended use and are not particularly limited as long as they do not impair the objectives of the present invention. However, it is preferable that each amount is 0.1 to 30% by mass relative to the total mass of the olefin polymer composition (M).

When producing a laminated film using the olefin polymer composition (M) of the present invention, the 4-methyl-1-pentene copolymer (A-1) and the olefin copolymer (B), etc., may be mixed in predetermined amounts and used, or they may be mixed and then kneaded to prepare the film.

<Surface layer (Y)>
The surface layer (Y) constituting the laminated film of the present invention is not particularly limited, and examples thereof include 4-methyl-1-pentene (co)polymer (A-2), polybutylene terephthalate, polyethylene fluoride, etc. Among these, it is preferable to use a 4-methyl-1-pentene (co)polymer (A-2) that satisfies the following requirements (g) to (i):

[4-methyl-1-pentene (co)polymer (A-2)]
The 4-methyl-1-pentene (co)polymer (A-2) (hereinafter, sometimes referred to as "polymer (A-2)") constituting the surface layer (Y) of the laminate film of the present invention is a homopolymer of 4-methyl-1-pentene or a copolymer of 4-methyl-1-pentene and an α-olefin that satisfies the following requirements (g) to (i):

<Requirement (g)>
The content of structural units derived from 4-methyl-1-pentene is 100 to 90 mol %, preferably 99.9 to 92 mol %, and more preferably 99 to 95 mol %, and the content of structural units derived from at least one selected from α-olefins having 10 to 20 carbon atoms (excluding 4-methyl-1-pentene) is 0 to 10 mol %, preferably 0.1 to 8 mol %, and more preferably 1 to 5 mol % (wherein the total amount of structural units derived from 4-methyl-1-pentene and structural units derived from ethylene and α-olefins having 10 to 20 carbon atoms is taken as 100 mol %).

<Requirement (h)>
The melting point (Tm) measured by DSC is in the range of 200 to 250°C, preferably 210 to 245°C, and more preferably 220 to 240°C.

<Requirement (i)>
The density is in the range of 820 to 850 kg/m ³ , preferably 825 to 845 kg/m ³ , and more preferably 830 to 840 kg/m ³ .

The 4-methyl-1-pentene (co)polymer (A-2) satisfying the above requirements (g) to (i) has excellent heat resistance, and by using the polymer (A-2) in the surface layer (Y), a laminated film having an excellent balance of releasability can be obtained.
The 4-methyl-1-pentene·α-olefin (co)polymer (A-2) preferably satisfies the following requirement (j) in addition to the above requirements (g) to (i).

<Requirement (j)>
The melt flow rate (MFR) of the 4-methyl-1-pentene/α-olefin (co)polymer (A-2) (measured according to ASTM D1238 at a temperature of 230°C and a load of 5.0 kgf) is preferably 1 to 200 g/10 min, more preferably 5 to 100 g/10 min, and even more preferably 10 to 60 g/10 min.

<Laminated film>
The laminated film of the present invention is a laminated film having at least two layers, namely, the substrate layer (X) and the surface layer (Y).

The laminated film of the present invention has a substrate layer (X) made of the olefin polymer composition (M), which has flexibility and good tear resistance. This allows for sufficient conformability even when shaping uneven molded articles, and suppresses linear expansion changes at high temperatures, resulting in excellent resistance to deformation and elongation during use, preventing film tearing, and preventing wrinkles even at high temperatures.

In addition, laminate films whose surface layer (Y) contains one or more of the above-mentioned 4-methyl-1-pentene (co)polymer (A-2), polybutylene terephthalate, and polyethylene fluoride can be used for molding at higher temperatures, and because their critical surface tension is small, they have excellent releasability from molded articles and molds.

The thickness of the laminate film of the present invention can be determined as desired, but typically, the thickness of the substrate layer (X) is in the range of 5 to 100 μm, preferably 10 to 80 μm, and more preferably 10 to 50 μm, the thickness of the surface layer (Y) is in the range of 3 to 50 μm, preferably 5 to 40 μm, and more preferably 5 to 20 μm, and the overall thickness of the laminate film is in the range of 20 to 200 μm, preferably 30 to 170 μm, and more preferably 50 to 150 μm.

The laminated film of the present invention may be a film in which the base layer (X) and the surface layer (Y) are in direct contact with each other, or may have an adhesive layer between the base layer (X) and the surface layer (Y) to improve the adhesive strength between the layers.

The laminate film of the present invention may be a two-layer film of substrate layer (X)/surface layer (Y), or may be a two-layer three-layer film of surface layer (Y)/substrate layer (X)/surface layer (Y), or may be a laminate film of three or more layers as long as it has a substrate layer (X) and a surface layer (Y).

When the laminate film of the present invention is a laminate film with three or more layers, the thicknesses of the surface layer (Y) and the base layer (X) each satisfy the above ranges, and the overall thickness of the laminate film is in the range of 20 to 200 μm, preferably 30 to 170 μm, and more preferably 50 to 150 μm.

<Method of manufacturing laminated film>
The laminated film of the present invention can be produced by using various known film forming machines.
Specifically, for example, a laminate film molding machine equipped with a lamination die (multilayer die) and at least two extruders is used, and the olefin polymer composition (M) to be the base layer (X) is charged into one extruder and the 4-methyl-1-pentene polymer (A-2) to be the surface layer (Y) is charged into the other extruder to produce a laminate film having a structure of base layer (X)/surface layer (Y) or surface layer (Y)/base layer (X)/surface layer (Y); a laminate film is produced by first molding the base layer (X) and then extrusion laminating the 4-methyl-1-pentene polymer (A-2) to be the surface layer (Y) onto the base layer (X); or a film to be the base layer (X) and a film to be the surface layer (Y) are separately produced, and then the respective films are surface-treated or an adhesive or the like to form a laminate film consisting of base layer (X)/surface layer (Y).

<Applications of laminated film>
The laminate film of the present invention can be used in various known applications, specifically, for example, release films for flexible printed circuit boards (FPC), release films for ACM substrates, release films for rigid substrates, release films for rigid-flexible substrates, release films for advanced composite materials, process release films for producing fiber reinforced composites, release films for curing carbon fiber composites, release films for molding carbon fiber composites, release films for curing glass fiber composites, release films for molding glass fiber composites, release films for curing aramid fiber composites, release films for molding aramid fiber composites, release films for curing nanocomposite materials, release films for curing filler materials, release films for sealing semiconductors, release films for polarizing plates, and release films for diffusion sheets. It can also be used as a release film for films such as films for films for prism sheets, release films for reflective sheets, cushion films for release films, release films for fuel cells, release films for various rubber sheets, release films for urethane curing, release films for epoxy curing, release films for silicone resins, release films for LED encapsulated molds, release films for acrylic adhesives, release films for protect films, and release films for synthetic leather, or as release papers such as release paper for synthetic leather, release paper for advanced composite materials, release paper for curing carbon fiber composites, release paper for curing glass fiber composites, release paper for curing aramid fiber composites, release paper for curing nanocomposite materials, and release paper for curing filler fillers, and heat-resistant, waterproof photographic paper.

The present invention will be explained below using examples, but the present invention is not limited to these examples in any way.

[Measurement conditions, etc.]
The measurement conditions for the following physical properties are as follows:

〔composition〕
The contents of the structural units (i) and (ii) in the copolymers (A-1) and polymers (A-2) obtained in the synthesis examples below were measured by ¹³ C-NMR using the following apparatus and conditions.

Measurements were performed using a JEOL Ltd. ECP500 nuclear magnetic resonance spectrometer with a mixed solvent of o-dichlorobenzene/heavy benzene (80/20 vol%) as the solvent, a sample concentration of 55 mg/0.6 mL, a measurement temperature of 120°C, an observation nucleus of ¹³ C (125 MHz), a sequence of single pulse proton decoupling, a pulse width of 4.7 μsec (45° pulse), a repetition time of 5.5 sec, and an accumulation count of 10,000 or more, with 27.50 ppm as the reference value for the chemical shift.

[Limiting viscosity]
The intrinsic viscosity [η] (dl/g) of the copolymer (A-1) and polymer (A-2) obtained in the following synthesis examples was measured at 135° C. using decalin as a solvent.

Specifically, approximately 20 mg of polymer was dissolved in 15 ml of decalin, and the specific viscosity η _sp was measured in an oil bath at 135°C. This decalin solution was diluted with 5 ml of decalin solvent, and the specific viscosity η _sp was measured in the same manner. This dilution procedure was repeated two more times, and the η _sp /C value when the concentration (C) was extrapolated to 0 was taken as the limiting viscosity [η] (unit: dl/g) as shown in the following formula (1).
[η]=lim(η _sp /C) (C→0) ...(1)

[Molecular weight and molecular weight distribution]
The molecular weights of the copolymer (A-1) and polymer (A-2) obtained in the following synthesis examples were measured using a liquid chromatograph: Waters ALC/GPC 150-C plus type (integrated with a differential refractometer detector), using two GMH6-HT columns and two GMH6-HTL columns (manufactured by Tosoh Corporation) connected in series, and o-dichlorobenzene as the mobile phase medium at a flow rate of 1.0 ml/min and 140° C. The measurement time per sample was 60 minutes.

The resulting chromatogram was analyzed using a calibration curve prepared using a standard polystyrene sample by a known method to measure the weight-average molecular weight (Mw) and number-average molecular weight (Mn), and calculate the molecular weight distribution (Mw/Mn).

〔density〕
The densities of the copolymer (A-1) and polymer (A-2) obtained in the following synthesis examples were calculated from the masses of each copolymer measured in water and air using an electronic densimeter MD-300S manufactured by Alpha Mirage Co., Ltd. in accordance with ASTM D 1505 (water displacement method).

[Melting point (Tm)]
The melting point (Tm) of the polymer was measured by differential scanning calorimetry (DSC) using a DSC220C device manufactured by Seiko Instruments Inc.

Specifically, 7 to 12 mg of copolymer (A-1) or polymer (A-2) obtained in the following synthesis example was sealed in an aluminum pan and heated from room temperature to 200°C at 10°C/min. The sample was then held at 200°C for 5 minutes to completely melt the copolymer, and then cooled to -50°C at 10°C/min. After remaining at -50°C for 5 minutes, the sample was heated again to 200°C at 10°C/min. The peak temperature during this second heating was used as the melting point (Tm).

[MFR]
According to ASTM D1238, the copolymer (A-1) was measured at a temperature of 230° C. and a load of 2.16 kgf, and the polymer (A-2) was measured at a temperature of 260° C. and a load of 5 kgf.

The physical properties of the laminated film were measured by the following methods.
[Tensile test]
The laminated film was cut into a strip shape of 15 mm wide x 100 mm long to prepare test specimens. The tensile modulus (YM) (unit: MPa), tensile strength (TS) (unit: MPa), and tensile elongation at break (EL) (unit: %) were measured in the MD and TD directions of the test specimens using a tensile tester (Universal Tensile Tester 3380, manufactured by Instron) in accordance with JIS K7127 (1999) under conditions of a chuck distance of 50 mm, a tensile speed of 200 mm/min, and a temperature of 23°C.

[Elmendrev tear strength]
The Elmendorf tear strength of the laminated film was measured in both the MD and TD directions under conditions of 23° C. and 55% RH using a light-load tearing device manufactured by Toyo Seiki Co., Ltd., in accordance with JIS K7128-1991.

[Linear expansion coefficient]
The laminated film was cut into a strip of 5 mm width × 10 mm length, and the test piece was subjected to a load of 5 gf (49 mN) using a TMA7100C (manufactured by Hitachi High-Technologies Corporation), and the temperature was raised from room temperature (23°C) to 180°C at a rate of 5°C/min in an extension mode, and the rate of change was calculated.

[Delamination]
The laminated film was cut into strips of 15 mm wide x 100 mm long (MD direction was the length direction) and the test pieces were measured in accordance with JIS K7127 (1999) using a tensile tester (Universal Tensile Tester 3380, manufactured by Instron) to create a trigger between the base layer (X) and the surface layer (Y), clamp the edges of each film with a chuck, and peel the test piece at an angle of 180° at a pulling speed of 300 mm/min and a temperature of 23°C. Furthermore, when the adhesive strength was so strong that a trigger could not be created, or when the films did not peel apart at the surface during the peel force measurement, resulting in holes or breaking midway (cohesive peeling), the peel strength was recorded as "not peeled" because it was sufficiently strong.

[Release property (contact angle measurement)]
The critical interfacial tension was measured using a DropMaster 500 image processing solid-liquid interface analysis system, using a wetting tension reagent mixture (manufactured by Wako Pure Chemical Industries, Ltd.) as the test liquid, in an environment of 23°C and 50% humidity, to measure the contact angle of the film obtained in the examples, and the critical interfacial tension was calculated based on the measured value. The smaller the critical interfacial tension, the higher the releasability for highly polar materials.

[Synthesis of 4-methyl-1-pentene copolymer (A-1)]
[Synthesis example A-1-1]
A 1.5-liter SUS autoclave equipped with a stirring blade and thoroughly purged with nitrogen was charged with 750 ml of 4-methyl-1-pentene at 23° C. 0.75 ml of a 1.0 mmol/ml toluene solution of triisobutylaluminum (TIBAL) was charged into the autoclave, and the stirrer was turned on.

Next, the autoclave was heated to an internal temperature of 60°C and pressurized with propylene to a total pressure of 0.13 MPa (gauge pressure). Subsequently, 0.34 ml of a toluene solution containing 1 mmol of pre-prepared methylaluminoxane (calculated as Al) and 0.01 mmol of diphenylmethylene(1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium dichloride was pressure-fed into the autoclave with nitrogen to initiate polymerization. During the polymerization reaction, the internal temperature of the autoclave was adjusted to 60°C. Sixty minutes after the start of polymerization, 5 ml of methanol was pressure-fed into the autoclave with nitrogen to terminate the polymerization, and the autoclave was depressurized to atmospheric pressure. Subsequently, acetone was poured into the reaction solution with stirring.

The resulting powdery polymer containing the solvent was dried at 100°C under reduced pressure for 12 hours. The amount of 4-methyl-1-pentene/α-olefin copolymer (A-1-1) obtained was 36.9 g, and the content of structural unit (i) in the polymer was 72.5 mol %, and the content of structural unit (ii) was 27.5 mol %. The physical properties of the resulting copolymer (A-1-1) are shown in Table 1.

[Synthesis example A-1-2]
A 1.5-liter stainless steel autoclave equipped with a stirring blade and thoroughly purged with nitrogen was charged with 300 ml of normal hexane (dried with activated alumina in a dry nitrogen atmosphere) and 450 ml of 4-methyl-1-pentene at 23° C. 0.75 ml of a 1.0 mmol/ml toluene solution of triisobutylaluminum (TIBAL) was charged into the autoclave, and the stirrer was turned on.

Next, the autoclave was heated to an internal temperature of 60°C and pressurized with propylene to a total pressure of 0.19 MPa (gauge pressure). Subsequently, 0.34 ml of a toluene solution containing 1 mmol of pre-prepared methylaluminoxane (calculated as Al) and 0.01 mmol of diphenylmethylene(1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium dichloride was pressure-fed into the autoclave with nitrogen to initiate polymerization. During the polymerization reaction, the internal temperature of the autoclave was adjusted to 60°C. Sixty minutes after the start of polymerization, 5 ml of methanol was pressure-fed into the autoclave with nitrogen to terminate the polymerization, and the autoclave was depressurized to atmospheric pressure. Subsequently, acetone was poured into the reaction solution with stirring.

The resulting powdered polymer containing the solvent was dried at 100°C under reduced pressure for 12 hours. The amount of copolymer (A-1-2) obtained was 44.0 g, and the content of structural unit (i) in the polymer was 84.1 mol %, and the content of structural unit (ii) was 15.9 mol %. The physical properties of the resulting copolymer are shown in Table 1.

[Production of 4-methyl-1-pentene (co)polymers (A-2-1) and (A-2-2)]
Copolymers (A-2-1) and (A-2-2) having the physical properties shown in Table 1 were obtained by changing the proportions of 4-methyl-1-pentene, 1-decene, 1-hexadecene, 1-octadecene, and hydrogen in accordance with the polymerization methods described in Comparative Examples 7 and 9 of WO 2006/054613.

[Example 1]
A composition blended with 100 parts by weight of copolymer (A-1-1) as the base layer (X) and 0.2 parts by weight of n-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenyl) propionate as a heat stabilizer, and 100 parts by weight of polymer (A-2-2) as the surface layer (Y) was used, and a 30 mmφ single-screw extruder was used. A three-type three-layer T-die molding machine with a die width of 300 mm was used, and the resin pellets for forming each layer were added from the resin supply hopper connected to each T-die for forming each layer. The resin pellets were melted through the cylinder in the single-screw extruder set at 260 to 280 ° C., and then extruded from the T-die at a die temperature of 270 ° C. to obtain a laminated film. The thickness of the surface layer (Y), base layer (X), and surface layer (Y) was extruded so that Y / X / Y = 10 / 30 / 10 μm. The physical properties of the resulting laminated film are shown in Table 2.

[Example 2]
A laminated film was obtained in the same manner as in Example 1, except that the copolymer (A-1-2) was used as the base layer (X) instead of the copolymer (A-1-1) used in Example 1. The physical properties of the obtained laminated film are shown in Table 2.

[Example 3]
A laminated film was obtained in the same manner as in Example 1, except that the polymer (A-2-1) was used for the surface layer (Y) instead of the polymer (A-2-2) used in Example 1. The physical properties of the obtained laminated film are shown in Table 2.

[Example 4]
A laminated film was obtained in the same manner as in Example 1, except that the copolymer (A-1-2) was used as the base layer (X) instead of the copolymer (A-1-1) used in Example 1, and the polymer (A-2-1) was used as the surface layer (Y) instead of the polymer (A-2-2) used in Example 1. The physical properties of the obtained laminated film are shown in Table 2.

[Example 5]
A laminated film was obtained in the same manner as in Example 1, except that the base layer (X) was a composition of 50 parts by mass of copolymer (A-1-2) instead of copolymer (A-1-1) used in Example 1 and 50 parts by mass of Vistamaxx 6202 (Tm = 110°C, MFR (230°C, load 2.16 kgf) = 20 g/10 min) manufactured by ExxonMobil Corporation as the propylene-based polymer (C-1), and the surface layer (Y) was a composition of polymer (A-2-1) instead of polymer (A-2-2) used in Example 1. The physical properties of the obtained laminated film are shown in Table 2.

[Example 6]
A laminated film was obtained in the same manner as in Example 1, except that the base layer (X) was a composition of 50 parts by mass of copolymer (A-1-2) instead of copolymer (A-1-1) used in Example 1 and 50 parts by mass of Prime Polypro F107BV (Tm = 160 ° C., MFR (230 ° C., load 2.16 kgf) = 7 g/10 min) manufactured by Prime Polymer Co., Ltd. as the propylene-based polymer (C-2), and the surface layer (Y) was a composition of 50 parts by mass of copolymer (A-1-2) instead of copolymer (A-1-1) used in Example 1. The physical properties of the obtained laminated film are shown in Table 2.

[Example 7]
A laminated film was obtained in the same manner as in Example 1, except that the base layer (X) was a composition of 20 parts by mass of 4-methyl-1-pentene/α-olefin copolymer (A-1-2) instead of the copolymer (A-1-1) used in Example 1 and 80 parts by mass of Prime Polypro F107BV (Tm = 160 ° C., MFR (230 ° C., load 2.16 kgf) = 7 g/10 min) manufactured by Prime Polymer Co., Ltd. as the propylene-based polymer (C-1), and the surface layer (Y) was a composition of 20 parts by mass of 4-methyl-1-pentene/α-olefin copolymer (A-1-2) instead of the copolymer (A-1-1) used in Example 1, and the surface layer (Y) was a composition of 80 parts by mass of Prime Polypro F107BV (Tm = 160 ° C., MFR (230 ° C., load 2.16 kgf) = 7 g/10 min) manufactured by Prime Polymer Co., Ltd. as the propylene-based polymer (C-1), and the surface layer (Y) was a composition of 20 parts by mass of 4-methyl-1-pentene/α-olefin copolymer (A-1-2) instead of the copolymer (A-1-1) used in Example 1. The physical properties of the obtained laminated film are shown in Table 2.

[Example 8]
A laminated film was obtained in the same manner as in Example 1, except that the base layer (X) was a composition of 5 parts by mass of copolymer (A-1-2) instead of copolymer (A-1-1) used in Example 1 and 95 parts by mass of Prime Polypro F107BV (Tm = 160 ° C., MFR (230 ° C., load 2.16 kgf) = 7 g/10 min) manufactured by Prime Polymer Co., Ltd. as the propylene-based polymer (C-1), and the surface layer (Y) was a composition of polymer (A-2-1) instead of polymer (A-2-2) used in Example 1. The physical properties of the obtained laminated film are shown in Table 2.

[Comparative Example 1]
A laminated film was obtained in the same manner as in Example 1, except that a propylene-based polymer (C-1) [Prime Polypro F107BV (Tm = 160°C, MFR (230°C, load 2.16 kgf) = 7 g/10 min) manufactured by Prime Polymer Co., Ltd.] was used as the base layer (X) instead of the copolymer (A-1-1) used in Example 1, and a polymer (A-2-1) was used as the surface layer (Y) instead of the polymer (A-2-2) used in Example 1. The physical properties of the obtained laminated film are shown in Table 2.

[Comparative Example 2]
A single-layer film was obtained in the same manner as in Example 1, except that a single-layer film composed of 100 parts by mass of polymer (A-2-2) was used instead of the laminated film used in Example 1. The physical properties of the obtained single-layer film are shown in Table 2.

[Comparative Example 3]
A single-layer film was obtained in the same manner as in Example 1, except that a single-layer film composed of 100 parts by mass of copolymer (A-1-2) was used instead of the laminated film used in Example 1. The physical properties of the obtained single-layer film are shown in Table 2.

Claims (9)

It comprises a substrate layer (X) and a surface layer (Y),
the base layer (X) is an olefin polymer composition (M) containing 5 to 100 parts by mass of a 4-methyl-1-pentene copolymer (A-1) satisfying the following requirements (a) to (e) , and 95 to 0 parts by mass of at least one olefin polymer (B) selected from a propylene polymer (C) and a butene polymer (E) (wherein the total of the components (A-1) and (B) is 100 parts by mass),
A laminated film characterized in that the surface layer (Y) contains at least one thermoplastic resin selected from the group consisting of 4-methyl-1-pentene (co)polymer, polybutylene terephthalate, and polyethylene fluoride:
[4-methyl-1-pentene copolymer (A-1)]
(a) 97 to 60 mol % of structural units derived from 4-methyl-1-pentene and 3 to 40 mol % of structural units derived from at least one selected from ethylene or an α-olefin having 3 to 4 carbon atoms (wherein the total amount of structural units derived from 4-methyl-1-pentene and structural units derived from ethylene or an α-olefin having 3 to 4 carbon atoms is 100 mol %),
(b) Intrinsic viscosity [η] measured in decalin at 135 ° C. is in the range of 0.5 to 5.0 dl / g;
(c) The melting point (Tm) measured by DSC is 199°C or less, or is substantially unobservable;
(d) the molecular weight distribution (Mw/Mn), which is the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn), measured by gel permeation chromatography (GPC), is in the range of 1.0 to 3.5, and (e) the density is in the range of 825 to 860 kg/ ^m3 . 2. The laminated film according to claim 1, wherein the thermoplastic resin is a 4-methyl-1-pentene (co)polymer (A-2) that satisfies the following requirements (g) to (i):
[4-methyl-1-pentene (co)polymer (A-2)]
(g) 100 to 90 mol % of structural units derived from 4-methyl-1-pentene and 0 to 10 mol % of structural units derived from at least one selected from α-olefins having 10 to 20 carbon atoms (excluding 4-methyl-1-pentene) (wherein the total amount of structural units derived from 4-methyl-1-pentene and structural units derived from α-olefins having 10 to 20 carbon atoms is 100 mol %),
(h) a melting point (Tm) measured by DSC in the range of 200-250°C, and (i) a density in the range of 820-850 kg/ ^m3 . The laminate film according to claim 1 or 2, characterized in that the olefin resin (B) constituting the olefin polymer composition (M) is a propylene polymer (C). The laminate film according to claim 3, characterized in that the propylene polymer (C) contains 70 to 100 mol % of structural units derived from propylene and 30 to 0 mol % of structural units derived from at least one selected from ethylene or an α-olefin having 4 to 20 carbon atoms (provided that the total amount of structural units derived from propylene and structural units derived from ethylene or an α-olefin having 4 to 20 carbon atoms is 100 mol %). The laminate film according to any one of claims 1 to 4, wherein the laminate film has a three or more layer structure consisting of a surface layer (Y), a base layer (X), and a surface layer (Y) in this order. The laminate film according to any one of claims 1 to 5, wherein the laminate film is obtained by a T-die film molding method. A release film for producing fiber-reinforced composite materials, comprising the laminate film described in any one of claims 1 to 6. A release film for producing flexible printed circuit boards, comprising the laminate film described in any one of claims 1 to 6. A release film for semiconductor fabrication, comprising the laminate film described in any one of claims 1 to 6.