JP7704516B2 - Varnish composition and method for producing polyimide film - Google Patents

Description

The present invention relates to a polyimide resin, a varnish composition containing the polyimide resin, and a method for producing a polyimide resin film using the varnish composition.

Polyimide resins have excellent heat resistance, mechanical strength, insulating properties, low dielectric constant, and other properties, and are therefore widely used as insulating and protective materials in various electrical and electronic components, such as electronic substrates, such as multilayer wiring boards, and various elements. In general, polyimide resins are formed by heat-treating at high temperatures a solution of polyamic acid, which is obtained by polymerizing a tetracarboxylic dianhydride component and a diamine component.

In recent years, communication devices such as mobile phones have become increasingly higher in frequency, which has led to demand for insulating parts that insulate metal wiring in communication devices to be able to handle higher frequencies.
Here, the higher the frequency, the greater the transmission loss, and the increased transmission loss causes the electrical signal to attenuate. Therefore, in order to accommodate the increase in frequency, it is necessary to reduce the transmission loss.
In this regard, polyimide resins have excellent high-frequency characteristics, exhibiting a low dielectric tangent and a low dielectric constant in the high-frequency band, and therefore have been attracting attention as a material capable of reducing transmission loss in various substrates and elements used in the high-frequency band.

As a polyimide resin with such excellent high-frequency characteristics, a polyimide resin obtained by imidizing at high temperature a polyamic acid obtained by reacting an aromatic tetracarboxylic dianhydride with a specific structure with diaminoquatphenyl has been proposed (Patent Document 1).

JP 2018-080315 A

However, the polyimide resin described in Patent Document 1 is formed by applying a varnish containing a polyamic acid precursor and then heating the applied film at a high temperature, as described above. Therefore, when manufacturing a substrate or element containing a polyimide resin, there is a significant restriction in terms of heat resistance in the selection of materials to be used together with the polyimide resin.
Furthermore, depending on the design of the substrate or element, there are cases where it is required to form the polyimide resin only in a minute area.

In view of the above circumstances, there is a demand for a polyimide resin that is soluble in an organic solvent and has photosensitivity that can be cured by the action of a photosensitive curing agent.
By using such a polyimide resin, a photosensitive varnish is obtained in which the photosensitive polyimide resin is dissolved in an organic solvent. By using such a photosensitive varnish, the varnish can be applied to a substrate or the like, and then the organic solvent can be removed from the applied film, after which a polyimide resin having a fine and precise shape can be formed by a photolithography method. According to this method, the polyimide resin can be formed without heating at a high temperature.

The present invention has been made in consideration of the above problems, and aims to provide a polyimide resin that is soluble in an organic solvent, has photosensitivity that can be cured by the action of a photosensitive curing agent, and gives a cured product with excellent dielectric properties in the high frequency band, a varnish composition containing the polyimide resin, and a method for producing a polyimide film using the varnish composition.

The inventors discovered that the above problems can be solved by bonding a radically polymerizable group or a cationic polymerizable group to the main chain of a polyimide resin and by including a skeleton derived from a bisphenol having a specific structure in the structural units that make up the main chain of the polyimide resin, and thus completed the present invention. More specifically, the present invention provides the following.

（式（Ａ１ａ）中、Ｘ^１は、ジアミンに由来する２価の有機残基であり、Ｙ^２は、テトラカルボン酸二無水物に由来する４価の有機残基である。）
で表される構成単位を含む分子鎖を有し、
Ｘ^１としての有機残基、及びＹ^１としての有機残基の少なくとも一方が、下記式（ａ１）：

（式（ａ１）中、Ｒ^ａ１及びＲ^ａ２は、それぞれ独立に、炭素原子数１以上４以下のアルキル基、炭素原子数１以上４以下のアルコキシ基、又はハロゲン原子であり、ｎ１及びｎ２は、それぞれ独立に０以上４以下の整数であり、Ｒ^ａ３及びＲ^ａ４は、それぞれ独立に、水素原子、炭素原子数１以上４以下のアルキル基、炭素原子数１以上４以下のハロゲン化アルキル基、又はフェニル基であり、Ｒ^ａ３とＲ^ａ４とは互いに結合して環を形成してもよい。）
で表される部分構造を有し、
分子鎖が、ラジカル重合性基、又はカチオン重合性基を含む、ポリイミド樹脂である。 The first aspect of the present invention is a method for producing a cellular membrane comprising the steps of:
The following formula (A1a):

In formula (A1a), ^X1 is a divalent organic residue derived from a diamine, and ^Y2 is a tetravalent organic residue derived from a tetracarboxylic dianhydride.
The molecular chain includes a structural unit represented by
At least one of the organic residue represented by ^X1 and the organic residue represented by ^Y1 is represented by the following formula (a1):

(In formula (a1), R ^a1 and R ^a2 each independently represent an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, or a halogen atom; n1 and n2 each independently represent an integer of from 0 to 4; R ^a3 and R ^a4 each independently represent a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, a halogenated alkyl group having from 1 to 4 carbon atoms, or a phenyl group; and R ^a3 and R ^a4 may be bonded to each other to form a ring.)
The partial structure represented by
The polyimide resin has a molecular chain containing a radically polymerizable group or a cationic polymerizable group.

The second aspect of the present invention is a varnish composition comprising the polyimide resin (A) according to the first aspect and an organic solvent (S).

A third aspect of the present invention is a method for producing a composition comprising the steps of:
A coating step of coating the varnish composition according to the second aspect onto a substrate to form a coating film;
an organic solvent removing step of removing at least a part of the organic solvent (S) from the coating film;
The method for producing a polyimide film includes the steps of:

The present invention provides a polyimide resin that is soluble in an organic solvent, has photosensitivity that allows it to be cured by the action of a photosensitive curing agent, and gives a cured product that has excellent dielectric properties in the high frequency band, a varnish composition that contains the polyimide resin, and a method for producing a polyimide film that uses the varnish composition.

（式（Ａ１ａ）中、Ｘ^１は、２価の有機基であり、Ｙ^１は、４価の有機基である。）
で表される構成単位を含む分子鎖を有する。 <Polyimide resin>
The polyimide resin has the following formula (A1a):

(In formula (A1a), ^X1 is a divalent organic group, and ^Y1 is a tetravalent organic group.)
The molecular chain includes a structural unit represented by the formula:

（式（ａ１）中、Ｒ^ａ１及びＲ^ａ２は、それぞれ独立に、炭素原子数１以上４以下のアルキル基、炭素原子数１以上４以下のアルコキシ基、又はハロゲン原子であり、ｎ１及びｎ２は、それぞれ独立に０以上４以下の整数であり、Ｒ^ａ３及びＲ^ａ４は、それぞれ独立に、水素原子、炭素原子数１以上４以下のアルキル基、炭素原子数１以上４以下のハロゲン化アルキル基、又はフェニル基であり、Ｒ^ａ３とＲ^ａ４とは互いに結合して環を形成してもよい。）
で表される部分構造を有する。 In the above formula (A1a), at least one of the divalent organic group represented by ^X1 and the tetravalent organic group represented by ^Y1 is represented by the following formula (a1):

(In formula (a1), R ^a1 and R ^a2 each independently represent an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, or a halogen atom; n1 and n2 each independently represent an integer of from 0 to 4; R ^a3 and R ^a4 each independently represent a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, a halogenated alkyl group having from 1 to 4 carbon atoms, or a phenyl group; and R ^a3 and R ^a4 may be bonded to each other to form a ring.)
It has a partial structure represented by the following formula:

Since the polyimide resin has the constitutional unit represented by the above formula (A1a), the polyimide resin is soluble in various organic solvents.
The content of the structural unit represented by the above formula (A1a) in the polyimide resin is not particularly limited as long as it does not impair the object of the present invention. The content of the structural unit represented by the above formula (A1a) in the polyimide resin is preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, more preferably 90 mass% or more, and particularly preferably 95 mass% or more, based on the mass of the polyimide resin.

The molecular chains of the polyimide resin contain radically polymerizable groups or cationic polymerizable groups. Therefore, the polyimide resin can be cured by the action of an initiator such as a radical polymerization initiator or a cationic polymerization initiator, and can become insoluble in organic solvents.

The bonding position of the radically polymerizable group or the cationic polymerizable group in the molecular chain of the polyimide resin is not particularly limited.
The radical polymerizable group typically includes a group containing an ethylenically unsaturated double bond. As the ethylenically unsaturated double bond-containing group, a vinyl group or an alkenyl group-containing group including an alkenyl group such as an allyl group is preferable, and a (meth)acryloyl group-containing group is more preferable.
The cationic polymerizable group typically includes an epoxy group-containing group, an oxetanyl group-containing group, a vinyloxy group-containing group, etc. Among these, the epoxy group-containing group and the vinyloxy group-containing group are preferred. As the epoxy group-containing group, an alicyclic epoxy group-containing group and a glycidyl group are preferred. Note that the alicyclic epoxy group is an aliphatic cyclic group in which two carbon atoms as adjacent ring constituent atoms in the aliphatic cyclic group are bonded via an oxygen atom. In other words, the alicyclic epoxy group has an epoxy group containing a three-membered ring consisting of two carbon atoms and one oxygen atom on the aliphatic ring.

The amount of radically polymerizable groups or cationic polymerizable groups in the polyimide resin is not particularly limited as long as it does not impair the object of the present invention. The amount of radically polymerizable groups or cationic polymerizable groups in the polyimide resin is, for example, preferably 0.0001 mol/g or more and 0.0500 mol/g or less, more preferably 0.0002 mol/g or more and 0.0100 mol/g or less, and even more preferably 0.0005 mol/g or more and 0.0020 mol/g or less, in terms of the number of moles of functional groups relative to the weight of the polyimide resin. The amount of radically polymerizable groups or cationic polymerizable groups in the polyimide resin can typically be measured by NMR analysis.

The radical polymerizable group is preferably bonded to an aromatic ring in the molecular chain of the polyimide resin. Suitable examples of the radical polymerizable group bonded to an aromatic ring in the molecular chain of the polyimide resin include groups represented by the following formula (A1) or (A2), which do not fall under the category of vinyloxy group-containing groups.
-(A ⁰¹ ) _na -R ⁰¹ ...(A1)
-(A ⁰¹ ) _na -R ⁰² -A ⁰² -R ⁰¹ ...(A2)

In formula (A1) and formula (A2), R ⁰¹ is an alkenyl group having 2 to 10 carbon atoms, and R ⁰² is an alkylene group having 1 to 10 carbon atoms.
A ⁰¹ is —O—, —CO—, —CO—O—, —O—CO—, —CO—NH—, —NH—CO—, or —NH—.
A ⁰² is -O-, -CO-, -CO-O-, -O-CO-, -CO-NH-, -NH-CO-, or -NH-.
na is 0 or 1.

Preferable specific examples of the radical polymerizable group bonded to the aromatic ring in the main chain include:
-O-R ⁰³ ,
-O-CH ₂ CH ₂ -O-R ⁰³ ,
-O-CH ₂ CH ₂ CH ₂ -O-R ⁰³ ,
-O-CH ₂ CH ₂ CH ₂ CH ₂ -O-R ⁰³ ,
-CO-O-CH ₂ CH ₂ -O-R ⁰³ ,
-CO-O-CH ₂ CH ₂ CH ₂ -O-R ⁰³ ,
-CO-O-CH ₂ CH ₂ CH ₂ CH ₂ -O-R ⁰³ ,
-O-CH ₂ CH ₂ -NH-R ⁰³ ,
-O-CH ₂ CH ₂ CH ₂ -NH-R ⁰³ ,
-O-CH ₂ CH ₂ CH ₂ CH ₂ -NH-R ⁰³ ,
-CO-O-CH ₂ CH ₂ -NH-R ⁰³ ,
-CO-O-CH ₂ CH ₂ CH ₂ -NH-R ⁰³ ,
-CO-O-CH ₂ CH ₂ CH ₂ CH ₂ -R ⁰³ ,
-NH-R ⁰³ ,
-NH-CH ₂ CH ₂ -O-R ⁰³ ,
-NH-CH ₂ CH ₂ CH ₂ -O-R ⁰³ ,
-NH-CH ₂ CH ₂ CH ₂ CH ₂ -O-R ⁰³ ,
-CO-NH-CH ₂ CH ₂ -O-R ⁰³ ,
-CO-NH-CH ₂ CH ₂ CH ₂ -O-R ⁰³ ,
-CO-NH-CH ₂ CH ₂ CH ₂ CH ₂ -O-R ⁰³ ,
-NH-CH ₂ CH ₂ -NH-R ⁰³ ,
-NH-CH ₂ CH ₂ CH ₂ -NH-R ⁰³ ,
-NH-CH ₂ CH ₂ CH ₂ CH ₂ -NH-R ⁰³ ,
-CO-NH-CH ₂ CH ₂ -NH-R ⁰³ ,
-CO-NH- _{CH2CH2CH2 - NH} - ^R03 , and
Examples of the groups include those represented by the formula: --CO--NH--CH ₂ CH ₂ CH ₂ CH ₂ --NH--R ^03. In these groups, R ⁰³ is an allyl group or a (meth)acryloyl group.

The cationically polymerizable group is preferably bonded to an aromatic ring in the molecular chain of the polyimide resin. Suitable examples of the cationically polymerizable group bonded to an aromatic ring in the molecular chain of the polyimide resin include a vinyloxy group and groups represented by the following formulae (A3) to (A8).
-(A ⁰¹ ) _na -R ⁰⁴ ...(A3)
-(A ⁰¹ ) _na -R ⁰² -R ⁰⁵ ...(A4)
-(A ⁰¹ ) _na -R ⁰² -(CO) _nb -A ⁰³ -R ⁰⁴ ...(A5)
-(A ⁰¹ ) _na -R ⁰² -(CO) _nb -A ⁰³ -R ⁰⁷ -R ⁰⁵ ...(A6)
-(A ⁰¹ ) _na -R ⁰² -O-R ⁰⁶ ...(A7)
-(A ⁰¹ ) _na -R ⁰² -(CO) _nb -A ⁰³ -R ⁰⁷ -O-R ⁰⁶ ...(A8)

In formulae (A3) to (A8), R ⁰² is an alkylene group having 1 to 10 carbon atoms. R ⁰⁴ is an epoxyalkyl group having 2 to 20 carbon atoms, or an alicyclic epoxy group having 3 to 20 carbon atoms. R ⁰⁵ is an alicyclic epoxy group having 3 to 20 carbon atoms. R ⁰⁶ is a vinyl group. R ⁰⁷ is an alkylene group having 1 to 10 carbon atoms.
A ⁰¹ is —O—, —CO—, —CO—O—, —O—CO—, —CO—NH—, —NH—CO—, or —NH—.
A ⁰³ is —O— or —NH—.
nb is 0 or 1.

Preferred specific examples of the cationically polymerizable group bonded to the aromatic ring in the main chain include:
-R ⁰⁷ ,
-O-CH ₂ CH ₂ -R ⁰⁷ ,
-O-CH ₂ CH ₂ CH ₂ -R ⁰⁷ ,
-O-CH ₂ CH ₂ CH ₂ CH ₂ -R ⁰⁷ ,
-CO-O-CH ₂ CH ₂ -R ⁰⁷ ,
-CO-O-CH ₂ CH ₂ CH ₂ -R ⁰⁷ ,
-CO-O-CH ₂ CH ₂ CH ₂ CH ₂ -R ⁰⁷ ,
-NH-CH ₂ CH ₂ -R ⁰⁷ ,
-NH-CH ₂ CH ₂ CH ₂ -R ⁰⁷ ,
-NH-CH ₂ CH ₂ CH ₂ CH ₂ -R ⁰⁷ ,
-CO-NH-CH ₂ CH ₂ -R ⁰⁷ ,
-CO-NH-CH ₂ CH ₂ CH ₂ -R ⁰⁷ , and
Illustrative examples include groups represented by the formula -CO-NH-CH ₂ CH ₂ CH ₂ CH ₂ -R ^07. In these groups, R ⁰⁷ is a vinyloxy group, a glycidyloxy group, an epoxycyclopentyl group, an epoxycyclohexyl group, or an epoxycycloheptyl group.

In the above formula (A1a), ^X1 is a divalent organic group. The divalent organic group is not particularly limited as long as it does not impair the object of the present invention. The divalent organic group is typically a divalent organic residue derived from a diamine used as a raw material for polyamic acid, which is a precursor of a polyimide resin.
In the above formula (A1a), ^Y1 is a tetravalent organic group. The tetravalent organic group is not particularly limited as long as it does not impair the object of the present invention. The tetravalent organic group is typically an organic residue of 4 derived from a tetracarboxylic dianhydride used as a raw material for polyamic acid, which is a precursor of a polyimide resin.
As described above, at least one of the organic group as ^X1 and the organic group as ^Y1 has the partial structure represented by the above formula (a1).

In formula (a1), examples of the alkyl group having 1 to 4 carbon atoms as R ^a1 and R ^a2 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, and a tert-butyl group. Among these alkyl groups, a methyl group and an ethyl group are preferred, and a methyl group is more preferred.
In formula (a1), examples of the alkoxy group having 1 to 4 carbon atoms as R ^a1 and R ^a2 include a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group, an isobutyloxy group, a sec-butyloxy group, and a tert-butyloxy group. Among these alkoxy groups, a methoxy group and an ethoxy group are preferred, and a methoxy group is more preferred.
In formula (a1), examples of the halogen atom represented by R ^a1 and R ^a2 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these halogen atoms, a chlorine atom and a bromine atom are preferred.

In formula (a1), n1 and n2 are each independently an integer of 0 to 4. Because of the ease of availability of monomer compounds for producing polyamic acid, which is a precursor of polyimide resin, n1 and n2 are each preferably an integer of 0 to 2, more preferably 0.

In formula (a1), examples of the alkyl group having 1 to 4 carbon atoms as R ^a3 and R ^a4 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, and a tert-butyl group.
In formula (a1), examples of the alkyl group having 1 to 4 carbon atoms as R ^a3 and R ^a4 include a chloromethyl group, a dichloromethyl group, a trichloromethyl group, a bromomethyl group, a dibromomethyl group, a tribromomethyl group, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 1,1-difluoroethyl group, and a 1,1,2,2,2-pentafluoroethyl group.
As R ^a3 and R ^a4 in formula (a1), a hydrogen atom, a methyl group, an ethyl group, a trifluoromethyl group, and a phenyl group are preferable, because the polyimide resin has good solubility in an organic solvent and a monomer compound for producing a polyamic acid, which is a precursor of a polyimide resin, is easily available.
It is also preferred that R ^a3 and R ^a4 combine with each other to form a cycloalkylidene group having 5 to 8 carbon atoms, such as a cyclopentylidene group, a cyclohexylidene group, a cycloheptylidene group, or a cyclooctylidene group.

Preferred specific examples of the partial structure represented by formula (a1) include the following structures.

（式（Ａ１ｂ）中、Ｘ^２及びＸ^３は、それぞれ独立に、炭素原子数１以上４以下のアルキル基、炭素原子数１以上４以下のアルコキシ基、及びハロゲン原子からなる群より選択される１以上の基で置換されていてもよい２価の芳香族炭化水素基であり、Ｙ^２は、式（ａ１）で表される部分構造を有さない４価の有機基であり、Ｒ^ａ１、Ｒ^ａ２、Ｒ^ａ３、Ｒ^ａ４、ｎ１、及びｎ２は、式（ａ１）中のこれらと同様である。）
で表される構成単位、下記式（Ａ１ｃ）：

（式（Ａ１ｃ）中、Ｘ^４は、式（ａ１）で表される部分構造を有さない２価の有機基であり、Ｙ^３及びＹ^４は、それぞれ独立に炭素原子数１以上４以下のアルキル基、炭素原子数１以上４以下のアルコキシ基、及びハロゲン原子からなる群より選択される１以上の基で置換されていてもよい３価の芳香族炭化水素基であり、Ｒ^ａ１、Ｒ^ａ２、Ｒ^ａ３、Ｒ^ａ４、ｎ１、及びｎ２は、式（ａ１）中のこれらと同様である。）
で表される構成単位、及び下記式（Ａ１ｄ）：

（式（Ａ１ｄ）中、Ｘ^５及びＸ^６は、それぞれ独立に、炭素原子数１以上４以下のアルキル基、炭素原子数１以上４以下のアルコキシ基、及びハロゲン原子からなる群より選択される１以上の基で置換されていてもよい２価の芳香族炭化水素基であり、Ｙ^５及びＹ^６は、それぞれ独立に、炭素原子数１以上４以下のアルキル基、炭素原子数１以上４以下のアルコキシ基、及びハロゲン原子からなる群より選択される１以上の基で置換されていてもよい３価の芳香族炭化水素基であり、Ｒ^ａ１、Ｒ^ａ２、Ｒ^ａ３、Ｒ^ａ４、ｎ１、及びｎ２は、式（ａ１）中のこれらと同様である。）
で表される構成単位からなる群より選択される１種以上を含むのが好ましい。 The molecular chain of the polyimide resin contains, as a constituent unit represented by formula (A1a), the following formula (A1b):

(In formula (A1b), ^X2 and ^X3 each independently represent a divalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom; ^Y2 represents a tetravalent organic group which does not have the partial structure represented by formula (a1); and R ^a1 , R ^a2 , R ^a3 , R ^a4 , n1, and n2 are the same as those in formula (a1).)
A structural unit represented by the following formula (A1c):

(In formula (A1c), ^X4 is a divalent organic group not having the partial structure represented by formula (a1), ^Y3 and ^Y4 are each independently a trivalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom, and R ^a1 , R ^a2 , R ^a3 , R ^a4 , n1, and n2 are the same as those in formula (a1).)
and a structural unit represented by the following formula (A1d):

(In formula (A1d), ^X5 and ^X6 are each independently a divalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom; ^Y5 and ^Y6 are each independently a trivalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom; and R ^a1 , R ^a2 , R ^a3 , R ^a4 , n1, and n2 are the same as those in formula (a1).)
It is preferable that the copolymer contains one or more structural units selected from the group consisting of structural units represented by the following formula:

In formula (A1b), ^X2 and ^X3 each independently represent a divalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom.
Examples of the alkyl group having 1 to 4 carbon atoms as a substituent 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, and a tert-butyl group. Among these alkyl groups, a methyl group and an ethyl group are preferred, and a methyl group is more preferred.
Examples of the alkoxy group having 1 to 4 carbon atoms as a substituent include a methoxy group, an ethoxy group, an n-propyloxy group, an isopropyloxy group, an n-butyloxy group, an isobutyloxy group, a sec-butyloxy group, and a tert-butyloxy group. Among these alkoxy groups, a methoxy group and an ethoxy group are preferred, and a methoxy group is more preferred.
Examples of the halogen atom as a substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these halogen atoms, a chlorine atom and a bromine atom are preferred.

The number of carbon atoms in the aromatic hydrocarbon group represented by ^X2 and ^X3 is not particularly limited, and is, for example, preferably from 6 to 50, and more preferably from 6 to 20. The number of carbon atoms in the aromatic hydrocarbon group does not include the number of carbon atoms of the substituent.
The aromatic hydrocarbon group represented by ^X2 and ^X3 is preferably a phenylene group such as an o-phenylene group, an m-phenylene group, or a p-phenylene group; a naphthalene-diyl group such as a naphthalene-1,4-diyl group, a naphthalene-1,3-diyl group, a naphthalene-2,6-diyl group, or a naphthalene-2,7-diyl group; or a biphenyldiyl group such as a biphenyl-4,4'-diyl group, a biphenyl-3,4'-diyl group, or a biphenyl-3,3'-diyl group.

^X2 and ^X3 are preferably a p-phenylene group, an m-phenylene group, a naphthalene-1,4-diyl group, or a biphenyl-4,4'-diyl group, more preferably a p-phenylene group or a biphenyl-4,4'-diyl group, and even more preferably a p-phenylene group.

（式（ａ１－１）中、Ａ^１は炭素原子数６以上５０以下の４価の有機基である。ただし、Ａ^１としての４価の有機基は、式（ａ１）で表される部分構造を含まない。） ^Y2 in formula (A1b) is a tetravalent organic group that does not have the partial structure represented by formula (a1). The tetravalent organic group represented by ^Y2 is typically a tetravalent organic residue derived from a tetracarboxylic dianhydride used as a raw material for polyamic acid, which is a precursor of a polyimide resin. Examples of tetracarboxylic dianhydrides that provide the tetravalent organic residue include compounds represented by the following formula (a1-1). The tetracarboxylic dianhydrides may be used alone or in combination of two or more.

(In formula (a1-1), A ¹ is a tetravalent organic group having 6 to 50 carbon atoms. However, the tetravalent organic group represented by A ¹ does not include a partial structure represented by formula (a1).)

In formula (a1-1), A ¹ is a tetravalent organic group having from 6 to 50 carbon atoms, and may have one or more substituents in addition to the two acid anhydride groups represented by -CO-O-CO- in formula (a1-1).
Preferred examples of the substituent include a fluorine atom, an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, a fluorinated alkyl group having from 1 to 6 carbon atoms, and a fluorinated alkoxy group having from 1 to 6 carbon atoms. The compound represented by formula (a1-1) may contain a carboxy group or a carboxylate group in addition to the acid anhydride group.
When the substituent is a fluorinated alkyl group or a fluorinated alkoxy group, it is preferably a perfluoroalkyl group or a perfluoroalkoxy group.
The same applies to the above-mentioned substituents for one or more substituents that the aromatic group described below may have on the aromatic ring.

The number of carbon atoms constituting A ¹ is more preferably 8 or more, and even more preferably 12 or more. The number of carbon atoms constituting A ¹ is more preferably 40 or less, and even more preferably 30 or less. ^{A 1} may be an aliphatic group, an aromatic group, or a group combining these structures. A ¹ may contain a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom in addition to a carbon atom and a hydrogen atom. When ^{A 1} contains an oxygen atom, a nitrogen atom, or a sulfur atom, the oxygen atom, the nitrogen atom, or the sulfur atom may be included in A ¹ as a group selected from a nitrogen-containing heterocyclic group, -CONH-, -NH-, -N=N-, -CH=N-, -COO-, -O-, -CO-, -SO-, -SO ₂ -, -S-, and -S-S-, and is more preferably included in A ¹ as a group selected from -O-, -CO-, -SO-, -SO ₂ -, -S-, and -S-S-.

The tetracarboxylic dianhydride represented by formula (a1-1) can be appropriately selected from tetracarboxylic dianhydrides that have been conventionally used as raw materials for synthesizing polyamic acids, so long as it satisfies the above-mentioned specified conditions. The tetracarboxylic dianhydride may be an aliphatic tetracarboxylic dianhydride or an aromatic tetracarboxylic dianhydride.

Examples of the aliphatic tetracarboxylic dianhydride include 2,2-bis(3,4-dicarboxy)propane dianhydride and bis(3,4-dicarboxy)methane dianhydride. The aliphatic tetracarboxylic dianhydride may also contain an alicyclic structure. The alicyclic structure may be polycyclic. Examples of the polycyclic alicyclic structure include bridged alicyclic structures such as bicyclo[2.2.1]heptane. For example, the bridged alicyclic structure may be condensed with another bridged alicyclic structure and/or a non-bridged alicyclic structure, and the bridged alicyclic structure may be linked to another bridged alicyclic structure and/or a non-bridged alicyclic structure by a spiro bond. When an aliphatic tetracarboxylic dianhydride is used, it is easy to obtain a cured product with excellent transparency using the composition.

（式（ａ２）中、Ｒ^ａ１１、Ｒ^ａ１２、及びＲ^ａ１３は、それぞれ独立に、水素原子、炭素原子数１以上５以下のアルキル基及びフッ素原子からなる群より選択される１種であり、ａは０以上１２以下の整数である。） As the aliphatic group constituting ^A1 in formula (a1-1), for example, a tetravalent group represented by the following formula (a2) can be used. When such a group is used, a polyimide resin having excellent transparency tends to be obtained.
In view of ease of purification of the raw material compound, a in formula (a2) is preferably 5 or less, more preferably 3 or less. In view of excellent chemical stability of the raw material compound that gives the structural unit represented by formula (a1), a is preferably 1 or more, more preferably 2 or more.
In formula (a2), a is particularly preferably 2 or 3.

(In formula (a2), R ^a11 , R ^a12 , and R ^a13 each independently represent one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and a fluorine atom, and a represents an integer of 0 to 12.)

Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 3,3',4,4'-oxybisphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride.

The aromatic tetracarboxylic dianhydride may also be, for example, a compound represented by the following general formulas (a1-2) to (a1-4).

In the above formulae (a1-2) and (a1-3), R ^a01 , R ^a02 and R ^a03 each represent an aliphatic group optionally substituted with halogen, an oxygen atom, a sulfur atom, an aromatic group having one or more divalent elements bonded thereto, or a divalent group constituted by a combination thereof. R ^a02 and R ^a03 may be the same or different.
That is, R ^a01 , R ^a02 and R ^a03 may contain a carbon-carbon single bond, a carbon-oxygen-carbon ether bond or a halogen element (fluorine, chlorine, bromine, iodine). Examples of the compound represented by formula (a1-2) include 2,2-bis(3,4-dicarboxyphenoxy)propane dianhydride and 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride.

In the above formula (a1-4), R ^a04 and R ^a05 are either an aliphatic group which may be substituted with halogen, an aromatic group via one or more divalent elements, or a halogen, or a monovalent substituent constituted by a combination thereof. R ^a04 and R ^a05 may be the same or different. As the compound represented by formula (a1-4), difluoropyromellitic dianhydride, dichloropyromellitic dianhydride, etc. can also be used.

式（Ａ１－１）～式（Ａ１－３）における、Ｒ^ａ０１、Ｒａ^０２、及びＲ^ａ０３は、前述の式（ａ１－１）、式（ａ１－２）、及び式（ａ１－３）における、Ｒ^ａ０１、Ｒａ^０２、及びＲ^ａ０３と同様である。
式（Ａ１－１）、式（Ａ１－２）、及び式（Ａ１－３）における、Ｒａ^０６は、ラジカル重合性基、又はカチオン重合性基である。ラジカル重合性基、又はカチオン重合性基としては、それぞれ前述の基が挙げられる。
テトラカルボン酸二無水物自体が反応性に富む。例えば、エポキシ基は、カルボン酸無水物基と容易に反応してしまう。このため、Ｙ^２が、式（Ａ１－１）、式（Ａ１－２）、又は式（Ａ１－３）で表される基である場合、ポリアミック酸、又はポリイミド樹脂を合成した後に、ポリアミック酸、又はポリイミド樹脂の分子鎖上に、ラジカル重合性基、又はカチオン重合性基導入するのが好ましい。 Moreover, the polyimide resin has a radically polymerizable group or a cationic polymerizable group on its molecular chain.
For this reason, the tetravalent organic group ^Y2 in formula (A1b) may be a group represented by the following formulae (A1-1) to (A1-3).

In formulae (A1-1) to (A1-3), R ^a01 , Ra ⁰² , and R ^a03 are the same as R ^a01 , Ra ⁰² , and R ^a03 in the above-mentioned formulae (a1-1), (a1-2), and (a1-3).
In formulae (A1-1), (A1-2), and (A1-3), Ra ⁰⁶ is a radical polymerizable group or a cationically polymerizable group. Examples of the radical polymerizable group or the cationically polymerizable group include the groups described above.
Tetracarboxylic dianhydride itself is highly reactive. For example, an epoxy group easily reacts with a carboxylic anhydride group. For this reason, when ^Y2 is a group represented by formula (A1-1), formula (A1-2), or formula (A1-3), it is preferable to introduce a radical polymerizable group or a cationic polymerizable group onto the molecular chain of the polyamic acid or polyimide resin after synthesizing the polyamic acid or polyimide resin.

Examples of reactions for introducing a radical polymerizable group or a cationic polymerizable group include:
1) An etherification reaction between a halogen atom bonded to an aromatic ring in a molecular chain of a polyamic acid or a polyimide resin and an alcohol compound having a radical polymerizable group or a cationic polymerizable group;
2) An esterification reaction between a hydroxyl group bonded to an aromatic ring in the molecular chain of a polyamic acid or a polyimide resin and a carboxylic acid halide having a radical polymerizable group or a cationically polymerizable group;
3) an esterification reaction between a carboxy group bonded to an aromatic ring in the molecular chain of a polyimide resin and an organic halide having a radical polymerizable group or a cationic polymerizable group; and
4) N-substitution reaction between an amino group bonded to an aromatic ring in the molecular chain of a polyamic acid or polyimide resin and an organic halide having a radical polymerizable group or a cationic polymerizable group. The reaction for introducing a radical polymerizable group or a cationic polymerizable group is not limited to these reactions.

For example, a polyamic acid or polyimide resin having a hydroxyl group protected by a protecting group such as an acetyl group, a carboxylate group such as a methoxycarbonyl group, or an amino group protected by a protecting group such as a tert-butoxycarbonyl group on an aromatic ring can be synthesized, and then deprotected by a known method to obtain a polyamic acid or polyimide resin having a hydroxyl group, carboxyl group, or amino group on an aromatic ring.

In formula (A1c), ^Y3 and ^Y4 each independently represent a trivalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom.
Preferred examples of the alkyl group having from 1 to 4 carbon atoms, the alkoxy group having from 1 to 4 carbon atoms, and the halogen atom as the substituent are the same as the preferred examples of the substituent that may be possessed by the aromatic hydrocarbon group as ^X2 and ^X3 in formula (A1b).

The number of carbon atoms in the aromatic hydrocarbon group represented by ^Y3 and ^Y4 is not particularly limited, and is, for example, preferably from 6 to 50, and more preferably from 6 to 20. The number of carbon atoms in the aromatic hydrocarbon group does not include the number of carbon atoms of the substituent.
Examples of the aromatic hydrocarbon group as ^Y3 and ^Y4 include benzenetriyl groups such as a benzene-1,2,3-triyl group and a benzene-1,2,4-triyl group, naphthalenetriyl groups such as a naphthalene-1,2,4-triyl group, a naphthalene-2,3,6-triyl group and a naphthalene-1,3,8-triyl group, and biphenyltriyl groups such as a biphenyl-3,4,4'-triyl group and a biphenyl-3,4,3'-triyl group.

^Y3 and ^Y4 are preferably a benzene-1,2,3-triyl group, a benzene-1,2,4-triyl group, a biphenyl-3,4,4'-triyl group, and a biphenyl-3,4,3'-triyl group, more preferably a benzene-1,2,4-triyl group and a biphenyl-3,4,4'-triyl group, and further preferably a benzene-1,2,4-triyl group.

^X4 in formula (A1c) is a divalent organic group that does not have the partial structure represented by formula (a1). The divalent organic group represented by ^X4 is typically a divalent organic residue derived from a diamine used as a raw material for a polyamic acid, which is a precursor of a polyimide resin.
Examples of diamines that provide the divalent organic residue include compounds represented by the following formula (a3-1). The compound represented by the following formula (a3-1) can be typically used. The diamine compounds may be used alone or in combination of two or more.
_H2NA2 - ^NH2 _... (a3-1)
(In formula (a3-1), ^A2 represents a divalent organic group. However, the divalent organic group represented by ^A2 does not include a partial structure represented by formula (a1).)

In formula (a3-1), ^A2 is a divalent organic group which may have one or more substituents in addition to the two amino groups in formula (a3-1).
Preferred examples of the substituent are a fluorine atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a hydroxyl group.
When the substituent is a fluorinated alkyl group or a fluorinated alkoxy group, it is preferably a perfluoroalkyl group or a perfluoroalkoxy group.

In formula (a3-1), the lower limit of the number of carbon atoms in the organic group for ^A2 is preferably 2, more preferably 6, and the upper limit is preferably 50, more preferably 30.
^A2 may be an aliphatic group, but is preferably an organic group containing one or more aromatic rings.

When ^A2 is an organic group containing one or more aromatic rings, the organic group may be one aromatic group itself, or may be a group in which two or more aromatic groups are bonded via an aliphatic hydrocarbon group, a halogenated aliphatic hydrocarbon group, or a bond containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. Examples of bonds containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom contained in ^A2 include -CONH-, -NH-, -N=N-, -CH=N-, -COO-, -O-, -CO-, -SO-, -SO ₂ -, -S-, and -S-S-, and -O-, -CO-, -SO-, -SO ₂ -, -S-, and -S-S- are preferred.

The aromatic ring bonded to the amino group in ^A2 is preferably a benzene ring. When the ring bonded to the amino group in ^A2 is a condensed ring containing two or more rings, the ring bonded to the amino group in the condensed ring is preferably a benzene ring.
The aromatic ring contained in ^A2 may be an aromatic heterocycle.

（式（２１）～（２４）中、Ｒ^１１１は、水素原子、フッ素原子、水酸基、炭素原子数１以上４以下のアルキル基、及び炭素原子数１以上４以下のハロゲン化アルキル基よりなる群から選択される１種を示す。式（２４）中、Ｑは、９，９’－フルオレニリデン基、又は、式：－Ｃ_６Ｈ_４－、－ＣＯＮＨ－Ｃ_６Ｈ_４－ＮＨＣＯ－、－ＮＨＣＯ－Ｃ_６Ｈ_４－ＣＯＮＨ－、－Ｏ－Ｃ_６Ｈ_４－ＣＯ－Ｃ_６Ｈ_４－Ｏ－、－ＯＣＯ－Ｃ_６Ｈ_４－ＣＯＯ－、－ＯＣＯ－Ｃ_６Ｈ_４－Ｃ_６Ｈ_４－ＣＯＯ－、－ＯＣＯ－、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＮＨ－、－ＳＯ_２－、－Ｃ（ＣＦ_３）_２－、－Ｃ（ＣＨ_３）_２－、－ＣＨ_２－、－Ｏ－Ｃ_６Ｈ_４－ＳＯ_２－Ｃ_６Ｈ_４－Ｏ－、－Ｃ（ＣＨ_３）_２－Ｃ_６Ｈ_４－Ｃ（ＣＨ_３）_２－、－Ｏ－Ｃ_１０Ｈ_６－Ｏ－、－Ｏ－Ｃ_６Ｈ_４－Ｃ_６Ｈ_４－Ｏ－、及び－Ｏ－Ｃ_６Ｈ_４－Ｏ－で表される基よりなる群から選択される１種を示す。
Ｑの例示における、－Ｃ_６Ｈ_４－はフェニレン基であり、ｍ－フェニレン基、及びｐ－フェニレン基が好ましく、ｐ－フェニレン基がより好ましい。また、－Ｃ_１０Ｈ_６－は、ナフタレンジイル基であり、ナフタレン－１，２－ジイル基、ナフタレン－１，４－ジイル基、ナフタレン－２，３－ジイル基、ナフタレン－２，６－ジイル基、及びナフタレン－２，７－ジイル基が好ましく、ナフタレン－１，４－ジイル基、及びナフタレン－２，６－ジイル基がより好ましい。） When ^A2 is an organic group containing an aromatic ring, from the viewpoint of the heat resistance of a cured product formed using the resin composition, the organic group is preferably at least one of the groups represented by the following formulas (21) to (24).

In formulae (21) to (24), R ¹¹¹ represents one selected from the group consisting of a hydrogen atom, a fluorine atom, a hydroxyl group, an alkyl group having from 1 to 4 carbon atoms, and a halogenated alkyl group having from 1 to 4 carbon atoms. In formula (24), Q represents a 9,9'-fluorenylidene group, or a group represented by the formula: -C ₆ H ₄ -, -CONH-C ₆ H ₄ -NHCO-, _-NHCO -C ₆ H ₄ -CONH-, -O-C _{6 H 4} -CO-C ₆ H ₄ -O-, -OCO-C ₆ H ₄ -COO-, -OCO-C ₆ H ₄ -C 6 H 4 -COO-, -OCO-, -O-, -S-, -CO-, -CONH-, -SO ₂ -, -C(CF ₃ ) _{2 This} represents one type selected from the group consisting of groups represented by -, -C(CH ₃ ) ₂ -, -CH ₂ -, -O-C ₆ H ₄ -SO _{2 -C 6} H ₄ -O-, -C(CH ₃ ) ₂ -C ₆ H ₄ -C(CH ₃ ) 2 -, -O-C ₁₀ H ₆ -O-, _-O -C ₆ H 4 -C 6 H 4 -O-, and -O-C _{6 H 4} -O-.
In the examples of Q, -C ₆ H ₄ - is a phenylene group, preferably an m-phenylene group or a p-phenylene group, more preferably a p-phenylene group. Also, -C ₁₀ H ₆ - is a naphthalenediyl group, preferably a naphthalene-1,2-diyl group, a naphthalene-1,4-diyl group, a naphthalene-2,3-diyl group, a naphthalene-2,6-diyl group, or a naphthalene-2,7-diyl group, more preferably a naphthalene-1,4-diyl group or a naphthalene-2,6-diyl group.

In terms of the heat resistance of the polyimide resin to be formed, R ¹¹¹ in formulas (21) to (24) is more preferably a hydrogen atom, a hydroxyl group, a fluorine atom, a methyl group, an ethyl group, or a trifluoromethyl group, and particularly preferably a hydrogen atom, a hydroxyl group, or a trifluoromethyl group.

In terms of the heat resistance of the polyimide resin formed, Q in formula (24) is preferably a 9,9'-fluorenylidene group, --O--C ₆ H ₄ --O--, --C(CF ₃ ) ₂ --, --O--, --C(CH ₃ ) ₂ --, --CH ₂ --, or --CONH--.

When an aromatic diamine is used as the diamine compound represented by formula (a3-1), for example, the aromatic diamines shown below can be suitably used.
That is, examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, 3,3'-diaminodiphenyl. aminobenzanilide, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, and 4,4'-[1,4-phenylenebis(1-methylethane-1,1-diyl)]dianiline, etc. Among these, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenyl ether, and 4,4'-diaminobenzanilide are preferred in terms of cost, availability, etc.

A ² may be a silicon-containing group which may have a chain-like aliphatic group and/or an aromatic ring. As such a silicon-containing group, the following groups can typically be used.

（式（Ｓｉ－１）中、Ｒ^１１２及びＲ^１１３は、それぞれ独立に、単結合又はメチレン基、炭素原子数２以上２０以下のアルキレン基、炭素原子数３以上２０以下のシクロアルキレン基、又は炭素原子数６以上２０以下のアリーレン基等であり、Ｒ^１１４、Ｒ^１１５、Ｒ^１１６、及びＲ^１１７は、それぞれ独立に、炭素原子数１以上２０以下のアルキル基、炭素原子数３以上２０以下のシクロアルキル基、炭素原子数６以上２０以下のアリール基、炭素原子数２０以下のアミノ基を含む基、－Ｏ－Ｒ^１１８で表される基（Ｒ^１１８は炭素原子数１以上２０以下の炭化水素基）、炭素原子数２以上２０以下の１以上のエポキシ基を含む有機基であり、ｌは、３以上５０以下の整数である。） From the viewpoint of further improving the mechanical properties of the resulting polyimide resin, a group represented by the following formula (Si-1) can also be preferably used as ^A2 .

(In formula (Si-1), R ¹¹² and R ¹¹³ are each independently a single bond or a methylene group, an alkylene group having from 2 to 20 carbon atoms, a cycloalkylene group having from 3 to 20 carbon atoms, or an arylene group having from 6 to 20 carbon atoms, etc.; R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ are each independently an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 3 to 20 carbon atoms, an aryl group having from 6 to 20 carbon atoms, a group containing an amino group having from 20 to 20 carbon atoms, a group represented by -O-R ¹¹⁸ (R ¹¹⁸ is a hydrocarbon group having from 1 to 20 carbon atoms), or an organic group containing one or more epoxy groups having from 2 to 20 carbon atoms, and l is an integer of from 3 to 50.)

In R ¹¹² and R ¹¹³ in formula (Si-1), the alkylene group having 2 to 20 carbon atoms is preferably an alkylene group having 2 to 10 carbon atoms from the viewpoint of heat resistance and residual stress, and examples of such groups include a dimethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group.

As the cycloalkylene group having 3 to 20 carbon atoms for R ¹¹² and R ¹¹³ in formula (Si-1), from the viewpoints of heat resistance and residual stress, a cycloalkylene group having 3 to 10 carbon atoms is preferable, and examples thereof include a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, and a cycloheptylene group.
In the formula (Si-1), the arylene group having 6 to 20 carbon atoms in R ¹¹² and R ¹¹³ is preferably an aromatic group having 6 to 20 carbon atoms in terms of heat resistance and residual stress, and examples of such groups include a phenylene group and a naphthylene group.

As the alkyl group having 1 to 20 carbon atoms for R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ in formula (Si-1), an alkyl group having 1 to 10 carbon atoms is preferable from the viewpoint of heat resistance and residual stress, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, and a hexyl group.
As the cycloalkyl group having 3 to 20 carbon atoms for R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ in formula (Si-1), a cycloalkyl group having 3 to 10 carbon atoms is preferable from the viewpoint of heat resistance and residual stress, and specific examples thereof include a cyclopentyl group, a cyclohexyl group, etc.
In the formula (Si-1), the aryl group having 6 to 20 carbon atoms for R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ is preferably an aryl group having 6 to 12 carbon atoms from the viewpoints of heat resistance and residual stress, and specific examples thereof include a phenyl group, a tolyl group, and a naphthyl group.
Examples of the amino group-containing group having 20 or less carbon atoms for R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ and R ¹¹⁷ in formula (Si-1) include an amino group and a substituted amino group (for example, a bis(trialkylsilyl)amino group).
Examples of the group represented by —O—R ¹¹⁸ in R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ in formula (Si-1) include a methoxy group, an ethoxy group, a propoxy group, an isopropyloxy group, a butoxy group, a phenoxy group, a tolyloxy group, a naphthyloxy group, a propenyloxy group (for example, an allyloxy group), and a cyclohexyloxy group.
Of these, R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ and R ¹¹⁷ are preferably a methyl group, an ethyl group, a propyl group or a phenyl group.

The group represented by formula (Si-1) can be derived by reacting a silicon-containing compound having amino groups at both ends with an acid anhydride. Specific examples of such silicon-containing compounds include methylphenyl silicone modified with amino groups at both ends (e.g., X-22-1660B-3 (number average molecular weight of about 4,400) and X-22-9409 (number average molecular weight of about 1,300) manufactured by Shin-Etsu Chemical Co., Ltd.), dimethyl silicone modified with amino groups at both ends (e.g., X-22-161A (number average molecular weight of about 1,600), X-22-161B (number average molecular weight of about 3,000) and KF8012 (number average molecular weight of about 4,400) manufactured by Shin-Etsu Chemical Co., Ltd.; BY16-835U (number average molecular weight of about 900) manufactured by Dow Corning Toray; and Silaplane FM3311 (number average molecular weight of about 1000) manufactured by JNC Corporation).

The polyimide resin has radically polymerizable groups or cationic polymerizable groups on its molecular chain.
For this reason, the divalent organic group ^X4 in formula (A1c) may be, for example, an aromatic group represented by any one of the above formulae (21) to (24) to which a radical polymerizable group or a cationically polymerizable group is further bonded on the aromatic ring.

Specific preferred examples of the organic group ^X4 having a radical polymerizable group or a cationically polymerizable group include the following groups.

In formula (A1d), ^X5 and ^X6 each independently represent a divalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom.
The divalent aromatic hydrocarbon groups represented by ^X5 and ^X6 are the same as the divalent aromatic hydrocarbon groups represented by ^X2 and ^X3 in formula (A1b).

In formula (A1d), ^Y5 and ^Y6 each independently represent a trivalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom.
The trivalent aromatic hydrocarbon group represented by ^Y5 and ^Y6 is the same as the trivalent aromatic hydrocarbon group represented by ^Y3 and ^Y4 in formula (A1c).

In formula (A1d), R ^a1 , R ^a2 , R ^a3 , R ^a4 , n1 and n2 are the same as those in formula (a1).

As the structural unit represented by formula (A1a), a structural unit represented by formula (A1c) is preferable, for example, because the raw materials for synthesizing the polyimide resin can be easily synthesized or obtained, and because it is easy to introduce a radically polymerizable group or a cationic polymerizable group into the structural unit.
The ratio of the mass of the structural unit represented by formula (A1c) to the mass of the structural unit represented by formula (A1a) is preferably 50 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and particularly preferably 100 mass%.

（式（Ａ１ｅ）中、Ｘ^４は、式（Ａ１ｃ）中のＸ^４と同様であり、Ｙ^２は、式（Ａ１ｂ）中のＹ^２と同様である。） The polyimide resin may contain a structural unit represented by the following formula (A1e) within the scope of not impairing the object of the present invention. The structural unit represented by the following formula (A1e) does not have the partial structure represented by the above formula (a1).

(In formula (A1e), ^X4 is the same as ^X4 in formula (A1c), and ^Y2 is the same as ^Y2 in formula (A1b).)

The method for producing the polyimide resin described above is not particularly limited. The polyimide resin described above can typically be produced by reacting a polyamic acid having a structure corresponding to the structure of the above-mentioned structural unit with a tetracarboxylic dianhydride to obtain a polyamic acid, and then imidizing the polyamic acid.
When producing the polyamic acid, the tetracarboxylic dianhydride and the diamine may each be used alone or in combination of two or more kinds.
As described above, the polyimide resin has a radical polymerizable group or a cationic polymerizable group. The radical polymerizable group or the cationic polymerizable group may be introduced onto the molecular chain after synthesis of the polyamic acid or after synthesis of the polyimide resin.
When a radically polymerizable group or a cationic polymerizable group is introduced onto the molecular chain of the polyamic acid or the polyimide resin (A) after synthesis of the polyamic acid or the polyimide resin (A), the method of introduction is not particularly limited.
Since an undesired side reaction is likely to occur between a carboxyl group or an amide bond and a radically polymerizable group or a cationic polymerizable group, it is preferable to introduce a radically polymerizable group or a cationic polymerizable group into the polyimide resin (A) rather than introducing a radically polymerizable group or a cationic polymerizable group into the polyamic acid.
Typical examples of methods for introducing a radical polymerizable group or a cationically polymerizable group onto a molecular chain include a method of reacting a polyamic acid having a functional group such as a hydroxyl group, an amino group, or a carboxyl group, or a polyimide resin (A) with a carboxylic acid having a radical polymerizable group, a carboxylic acid halide having a radical polymerizable group, an alcohol having a radical polymerizable group, a phenol having a radical polymerizable group, an amine having a radical polymerizable group, a halogenated compound having a radical polymerizable group, a carboxylic acid having a cationically polymerizable group, a carboxylic acid halide having a cationically polymerizable group, an alcohol having a cationically polymerizable group, a phenol having a cationically polymerizable group, an amine having a cationically polymerizable group, or a halogenated compound having a cationically polymerizable group by a known method such as a condensation reaction using a known condensing agent or Williamson's etherification reaction.

The amounts of the tetracarboxylic dianhydride and the diamine compound used in synthesizing the polyamic acid are not particularly limited, but the amount of the diamine compound used is preferably 0.50 mol or more and 1.50 mol or less, more preferably 0.60 mol or more and 1.30 mol or less, and particularly preferably 0.70 mol or more and 1.20 mol or less, per 1 mol of the tetracarboxylic dianhydride.
The weight average molecular weight of the polyamic acid obtained may be appropriately set depending on the application. The weight average molecular weight of the polyamic acid is, for example, 5,000 or more, preferably 7,500 or more, and more preferably 10,000 or more. On the other hand, the weight average molecular weight of the polyamic acid obtained is, for example, 100,000 or less, preferably 80,000 or less, and more preferably 75,000 or less.
The weight average molecular weight can be adjusted to the above-mentioned value by adjusting the amounts of the tetracarboxylic dianhydride and the diamine compound mixed together, and reaction conditions such as the solvent and reaction temperature.

The reaction between the tetracarboxylic dianhydride and the diamine compound is usually carried out in an organic solvent. The organic solvent used for the reaction between the tetracarboxylic dianhydride and the diamine compound is not particularly limited as long as it can dissolve the tetracarboxylic dianhydride and the diamine compound and does not react with the tetracarboxylic dianhydride and the diamine compound. The organic solvent can be used alone or in combination of two or more kinds.

Examples of organic solvents used in the reaction between tetracarboxylic dianhydride and diamine compound include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylcaprolactam, and N,N,N',N'-tetramethylurea; dimethyl sulfoxide; acetonitrile; and ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dioxane, and tetrahydrofuran.

Among these organic solvents, nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylcaprolactam, and N,N,N',N'-tetramethylurea are preferred from the viewpoint of the solubility of the resulting polyamic acid and polyimide resin.

The temperature at which the tetracarboxylic dianhydride and the diamine compound are reacted is not particularly limited as long as the reaction proceeds smoothly. Typically, the reaction temperature between the tetracarboxylic dianhydride and the diamine compound is preferably from -5°C to 150°C, more preferably from 0°C to 120°C, and particularly preferably from 0°C to 70°C. The time for reacting the tetracarboxylic dianhydride and the diamine compound varies depending on the reaction temperature, but typically, it is preferably from 1 hour to 50 hours, more preferably from 2 hours to 40 hours, and particularly preferably from 5 hours to 30 hours.

By the method described above, a solution containing a polyamic acid is obtained.
The resulting polyamic acid is imidized by ring closure to produce a polyimide resin (A).
The method of imidization is not particularly limited. The imidization may be performed by heating or using an imidizing agent.

When the imidization is performed by heating, the heating may be performed on a solution or suspension of the polyamic acid, or on a solid polyamic acid. Since the polyimide resin (A) exhibits excellent solubility in organic solvents, it is preferable to heat the polyamic acid solution for the imidization.
When the polyamic acid solution is heated to carry out the imidization, it is preferable to carry out the heating while removing water generated as a by-product during the imidization.
The heating conditions for imidization are not particularly limited as long as the polyamic acid or polyimide resin (A) is not decomposed and the imidization proceeds satisfactorily.
When the polyamic acid solution is heated, the heating temperature is typically preferably from 150° C. to 280° C., more preferably from 160° C. to 250° C., and particularly preferably from 170° C. to 230° C. When the solid polyamic acid is heated, the heating temperature is typically preferably from 180° C. to 400° C., and more preferably from 200° C. to 350° C.
The heating time varies depending on the heating temperature, but is typically preferably from 1 hour to 24 hours, more preferably from 2 hours to 12 hours.

When imidizing a polyamic acid with an imidizing agent, the imidization is usually carried out by adding the imidizing agent to a solution or suspension of the polyamic acid. As an organic solvent that can be used when imidizing with an imidizing agent, for example, the same organic solvent that can be used for preparing the polyamic acid can be used.
When imidization is performed using an imidizing agent, the concentration of the polyamic acid in the solution or suspension of the polyamic acid is not particularly limited. Typically, the concentration of the polyamic acid in the solution or suspension of the polyamic acid is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 30% by mass or less.
The amount of the imidizing agent used is not particularly limited, and is selected depending on the type of the imidizing agent so that the polyamic acid is imidized to a desired degree.
The reaction temperature when imidization is performed using an imidizing agent is not particularly limited. The reaction temperature is, for example, preferably 0° C. or higher and 100° C. or lower, and more preferably 5° C. or higher and 50° C. or lower.
The time for the imidization reaction when an imidizing agent is used is not particularly limited. The imidization reaction is preferably carried out for about 30 minutes to 24 hours, more preferably for 1 hour to 12 hours, and even more preferably for 2 hours to 6 hours, depending on the type of the imidizing agent.

Imidizing agents include dehydrating agents such as acetic anhydride, propionic anhydride, benzoic anhydride, trifluoroacetic anhydride, acetyl chloride, tosyl chloride, mesyl chloride, ethyl chloroformate, triphenylphosphine and dibenzimidazolyl disulfide, dicyclohexylcarbodiimide, carbodiimidazole, 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline, and oxalic acid N,N'-disuccinimidyl ester, and basic compounds such as pyridine, picoline, 2,6-lutidine, collidine, triethylamine, N-methylmorpholine, 4-N,N'-dimethylaminopyridine, isoquinoline, triethylamine, 1,4-diazabicyclo[2.2.2]octane, and 1,8-diazabicyclo[5.4.0]-7-undecene.

<Varnish composition>
The varnish composition contains the polyimide resin as the polyimide resin (A) in the organic solvent (S). As described above, the polyimide resin (A) is soluble in the organic solvent (S). Therefore, in the varnish composition, at least a part of the polyimide resin (A) is dissolved in the organic solvent (S). In the varnish composition, at 20° C., it is preferable that 80% by mass or more of the polyimide resin (A) is dissolved in the organic solvent (S), more preferably 90% by mass or more of the polyimide resin (A) is dissolved in the organic solvent (S), and particularly preferably 100% by mass or more of the polyimide resin (A) is dissolved in the organic solvent (S).
In other words, the varnish composition is preferably a solution in which the polyimide resin (A) is completely dissolved in the organic solvent (S).

The ratio of the mass of the polyimide resin (A) to the mass of the varnish composition is appropriately determined taking into consideration the viscosity of the varnish composition, taking into account the coating method and the thickness of the coating film. The ratio of the mass of the polyimide resin (A) to the mass of the varnish composition is typically preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

When the polyimide resin (A) has a radical polymerizable group, the varnish composition may contain, in addition to the polyimide resin (A), a monomer compound having an ethylenically unsaturated double bond as the monomer compound (B). Such a monomer compound may be a monofunctional monomer compound or a polyfunctional monomer compound, and a polyfunctional monomer compound is preferred.

Examples of monofunctional monomer compounds include (meth)acrylamide, methylol (meth)acrylamide, methoxymethyl (meth)acrylamide, ethoxymethyl (meth)acrylamide, propoxymethyl (meth)acrylamide, butoxymethoxymethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, (meth)acrylic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, crotonic acid, 2-acrylamido-2-methylpropanesulfonic acid, tert-butylacrylamidosulfonic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, Examples of the monomers include 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-phenoxy-2-hydroxypropyl (meth)acrylate, 2-(meth)acryloyloxy-2-hydroxypropyl phthalate, glycerin mono(meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dimethylamino (meth)acrylate, glycidyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, and half (meth)acrylate of phthalic acid derivatives. These monofunctional photopolymerizable monomers can be used alone or in combination of two or more.

Examples of polyfunctional monomer compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis Examples of polyfunctional monomer compounds include (4-(meth)acryloxypolyethoxyphenyl)propane, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, glycerin triacrylate, glycerin polyglycidyl ether poly(meth)acrylate, urethane (meth)acrylate (i.e., tolylene diisocyanate), a reaction product of trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, and 2-hydroxyethyl (meth)acrylate, methylene bis(meth)acrylamide, (meth)acrylamide methylene ether, and a condensation product of a polyhydric alcohol and N-methylol (meth)acrylamide, and triacrylformal. These polyfunctional monomer compounds can be used alone or in combination of two or more.

Among these monomer compounds having an ethylenically unsaturated double bond, polyfunctional monomer compounds having three or more functionalities are preferred, polyfunctional monomer compounds having four or more functionalities are more preferred, and polyfunctional monomer compounds having five or more functionalities are even more preferred, because they tend to increase the adhesion of the cured product to the substrate and the strength of the cured product.

When the polyimide resin (A) has a vinyloxy group-containing group as a cationic polymerizable group, the varnish composition may contain a vinyl ether compound as a monomer compound (B) together with the polyimide resin (A). Such a vinyl ether compound may be a monofunctional compound or a polyfunctional compound.

Specific examples of suitable vinyl ether compounds include vinyl phenyl ether, 4-vinyloxytoluene, 3-vinyloxytoluene, 2-vinyloxytoluene, 1-vinyloxy-4-chlorobenzene, 1-vinyloxy-3-chlorobenzene, 1-vinyloxy-2-chlorobenzene, 1-vinyloxy-2,3-dimethylbenzene, 1-vinyloxy-2,4-dimethylbenzene, 1-vinyloxy-2,5-dimethylbenzene, and 1-vinyloxy-2,6-dimethylbenzene. Aromatic monovinyl ethers such as methylbenzene, 1-vinyloxy-3,4-dimethylbenzene, 1-vinyloxy-3,5-dimethylbenzene, 1-vinyloxynaphthalene, 2-vinyloxynaphthalene, 2-vinyloxyfluorene, 3-vinyloxyfluorene, 4-vinyloxy-1,1'-biphenyl, 3-vinyloxy-1,1'-biphenyl, 2-vinyloxy-1,1'-biphenyl, 6-vinyloxytetralin, and 5-vinyloxytetralin. Compound: 1,4-divinyloxybenzene, 1,3-divinyloxybenzene, 1,2-divinyloxybenzene, 1,4-divinyloxynaphthalene, 1,3-divinyloxynaphthalene, 1,2-divinyloxynaphthalene, 1,5-divinyloxynaphthalene, 1,6-divinyloxynaphthalene, 1,7-divinyloxynaphthalene, 1,8-divinyloxynaphthalene, 2,3-divinyloxynaphthalene, 2,6-divinyloxynaphthalene, 2,7-divinyloxy aromatic divinyloxy ether compounds such as divinyloxynaphthalene, 1,2-divinyloxyfluorene, 3,4-divinyloxyfluorene, 2,7-divinyloxyfluorene, 4,4'-divinyloxybiphenyl, 3,3'-divinyloxybiphenyl, 2,2'-divinyloxybiphenyl, 3,4'-divinyloxybiphenyl, 2,3'-divinyloxybiphenyl, 2,4'-divinyloxybiphenyl, and bisphenol A divinyl ether.
These vinyl ether compounds may be used in combination of two or more kinds.

When the polyimide resin (A) has an epoxy group-containing group as the cationically polymerizable group, the varnish composition may contain various epoxy compounds as the monomer compound (B).
Examples of the epoxy compound include bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, naphthalene type epoxy resin, and biphenyl type epoxy resin; novolac epoxy resins such as phenol novolac type epoxy resin, brominated phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, and bisphenol AD novolac type epoxy resin; cyclic aliphatic epoxy resins such as epoxidized products of dicyclopentadiene type phenol resin; aromatic epoxy resins such as epoxidized products of naphthalene type phenol resin; glycidyl ester type epoxy resins such as dimer acid glycidyl ester and triglycidyl ester; glycidyl amine type epoxy resins such as tetraglycidylaminodiphenylmethane, triglycidyl-p-aminophenol, tetraglycidylmeta-xylylenediamine, and tetraglycidylbisaminomethylcyclohexane; triglycidyl heterocyclic epoxy resins such as phenylmethyl isocyanurate; phloroglucinol triglycidyl ether, trihydroxybiphenyl triglycidyl ether, trihydroxyphenylmethane triglycidyl ether, glycerin triglycidyl ether, 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-(2,3-epoxypropoxy)phenyl]ethyl]phenyl]propane, and 1,3-bis[4-[1-[4-(2,3-epoxypropoxy)phenyl]-1-[4- trifunctional epoxy resins such as [1-[4-(2,3-epoxypropoxy)phenyl]-1-methylethyl]phenyl]ethyl]phenoxy]-2-propanol; tetrafunctional epoxy resins such as tetrahydroxyphenylethane tetraglycidyl ether, tetraglycidylbenzophenone, bisresorcinol tetraglycidyl ether, and tetraglycidoxybiphenyl; and 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol. The 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol is commercially available as EHPE-3150 (manufactured by Daicel Corporation).

Furthermore, oligomer or polymer type polyfunctional epoxy compounds can also be preferably used.
Typical examples of oligomer or polymer type polyfunctional epoxy compounds include phenol novolac type epoxy compounds, brominated phenol novolac type epoxy compounds, orthocresol novolac type epoxy compounds, xylenol novolac type epoxy compounds, naphthol novolac type epoxy compounds, bisphenol A novolac type epoxy compounds, bisphenol AD novolac type epoxy compounds, epoxidized products of dicyclopentadiene type phenolic resins, and epoxidized products of naphthalene type phenolic resins.

Other examples of suitable epoxy compounds include polyfunctional alicyclic epoxy compounds having alicyclic epoxy groups.

Specific examples of alicyclic epoxy compounds include 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane, bis(3,4-epoxycyclohexylmethyl)adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate, ε-caprolactone-modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, trimethylcaprolactone-modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, Examples of epoxycyclohexane carboxylate, β-methyl-δ-valerolactone modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate, methylene bis(3,4-epoxycyclohexane), di(3,4-epoxycyclohexylmethyl)ether of ethylene glycol, ethylene bis(3,4-epoxycyclohexane carboxylate), dioctyl epoxycyclohexahydrophthalate, and di-2-ethylhexyl epoxycyclohexahydrophthalate, epoxy resins having tricyclodecene oxide groups, and compounds represented by the following formulas (b01-1) to (b01-5) are included.

Among these specific examples of alicyclic epoxy compounds, the alicyclic epoxy compounds represented by the following formulas (b01-1) to (b01-5) are preferred because they give cured products with high hardness.

（式（ｂ０１－１）中、Ｚ^０１は単結合又は連結基（１以上の原子を有する２価の基）を示す。Ｒ^ｂ０１～Ｒ^ｂ０１８は、それぞれ独立に、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。）

(In formula (b01-1), Z ⁰¹ represents a single bond or a linking group (a divalent group having one or more atoms). ^{R b01} to R ^b018 each independently represent a group selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group.)

Examples of the linking group Z ⁰¹ include divalent groups selected from the group consisting of divalent hydrocarbon groups, -O-, -O-CO-, -S-, -SO-, -SO ₂ -, -CBr ₂ -, -C(CBr ₃ ) ₂ -, -C(CF ₃ ) ₂ -, and -R ^b019 -O-CO-, and groups in which a plurality of these are bonded together.

Examples of the divalent hydrocarbon group which is the linking group ^Z01 include a linear or branched alkylene group having from 1 to 18 carbon atoms and a divalent alicyclic hydrocarbon group. Examples of the linear or branched alkylene group having from 1 to 18 carbon atoms include a methylene group, a methylmethylene group, a dimethylmethylene group, a dimethylene group, and a trimethylene group. Examples of the divalent alicyclic hydrocarbon group include a cycloalkylene group (including a cycloalkylidene group) such as a 1,2-cyclopentylene group, a 1,3-cyclopentylene group, a cyclopentylidene group, a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, a 1,4-cyclohexylene group, and a cyclohexylidene group.

R ^b019 is an alkylene group having 1 to 8 carbon atoms, and is preferably a methylene group or an ethylene group.

（式（ｂ０１－２）中、Ｒ^ｂ０１～Ｒ^ｂ０１８は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。Ｒ^ｂ０２及びＲ^ｂ０１０は、互いに結合してもよい。Ｒ^ｂ０１３及びＲ^ｂ０１６は互いに結合して環を形成してもよい。ｍ^ａ１は、０又は１である。）

(In formula (b01-2), R ^b01 to R ^b018 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group. R ^b02 and R ^b010 may be bonded to each other. R ^b013 and R ^b016 may be bonded to each other to form a ring. ^{m a1} is 0 or 1.)

（式（ｂ０１－２－１）中、Ｒ^ｂ０１～Ｒ^ｂ０１２は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。Ｒ^ｂ０２及びＲ^ｂ０１０は互いに結合して環を形成してもよい。） As the alicyclic epoxy compound represented by the above formula (b01-2), a compound represented by the following formula (b01-2-1), which corresponds to the compound in which m ^a1 in the above formula (b01-2) is 0, is preferable.

(In formula (b01-2-1), R ^b01 to R ^b012 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group. ^{R b02} and R ^b010 may be bonded to each other to form a ring.)

（式（ｂ０１－３）中、Ｒ^ｂ０１～Ｒ^ｂ０１０は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。Ｒ^ｂ０２及びＲ^ｂ０８は、互いに結合してもよい。）

(In formula (b01-3), R ^b01 to R ^b010 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group. R ^b02 and R ^b08 may be bonded to each other.)

（式（ｂ０１－４）中、Ｒ^ｂ０１～Ｒ^ｂ０１２は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。Ｒ^ｂ０２及びＲ^ｂ０１０は、互いに結合してもよい。）

(In formula (b01-4), R ^b01 to R ^b012 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group. R ^b02 and R ^b010 may be bonded to each other.)

（式（ｂ０１－５）中、Ｒ^ｂ０１～Ｒ^ｂ０１２は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。）

(In formula (b01-5), R ^b01 to R ^b012 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group.)

In formulae (b01-1) to (b01-5), when R ^b01 to R ^b018 are organic groups, the organic group is not particularly limited as long as it does not impair the object of the present invention, and may be a hydrocarbon group, a group consisting of carbon atoms and halogen atoms, or a group containing heteroatoms such as halogen atoms, oxygen atoms, sulfur atoms, nitrogen atoms, and silicon atoms in addition to carbon atoms and hydrogen atoms. Examples of halogen atoms include chlorine atoms, bromine atoms, iodine atoms, and fluorine atoms.

As the organic group, a hydrocarbon group, a group consisting of carbon atoms, hydrogen atoms, and oxygen atoms, a halogenated hydrocarbon group, a group consisting of carbon atoms, oxygen atoms, and halogen atoms, and a group consisting of carbon atoms, hydrogen atoms, oxygen atoms, and halogen atoms are preferred. When the organic group is a hydrocarbon group, the hydrocarbon group may be an aromatic hydrocarbon group, an aliphatic hydrocarbon group, or a group containing an aromatic skeleton and an aliphatic skeleton. The number of carbon atoms in the organic group is preferably 1 to 20, more preferably 1 to 10, and particularly preferably 1 to 5.

Specific examples of hydrocarbon groups include chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-icosyl; vinyl, 1-propenyl, 2-n-propenyl (allyl), and 1-n-butenyl. , 2-n-butenyl, and 3-n-butenyl; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl; aryl groups such as phenyl, o-tolyl, m-tolyl, p-tolyl, α-naphthyl, β-naphthyl, biphenyl-4-yl, biphenyl-3-yl, biphenyl-2-yl, anthryl, and phenanthryl; and aralkyl groups such as benzyl, phenethyl, α-naphthylmethyl, β-naphthylmethyl, α-naphthylethyl, and β-naphthylethyl.

Specific examples of halogenated hydrocarbon groups include halogenated chain alkyl groups such as chloromethyl, dichloromethyl, trichloromethyl, bromomethyl, dibromomethyl, tribromomethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, heptafluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, perfluoroheptyl, perfluorooctyl, perfluorononyl, and perfluorodecyl; halogenated cyclohexyl groups such as 2-chlorocyclohexyl, 3-chlorocyclohexyl, 4-chlorocyclohexyl, 2,4-dichlorocyclohexyl, 2-bromocyclohexyl, 3-bromocyclohexyl, and 4-bromocyclohexyl. Chloroalkyl groups; halogenated aryl groups such as 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,3-dichlorophenyl, 2,4-dichlorophenyl, 2,5-dichlorophenyl, 2,6-dichlorophenyl, 3,4-dichlorophenyl, 3,5-dichlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-fluorophenyl, 3-fluorophenyl, and 4-fluorophenyl groups; halogenated aralkyl groups such as 2-chlorophenylmethyl, 3-chlorophenylmethyl, 4-chlorophenylmethyl, 2-bromophenylmethyl, 3-bromophenylmethyl, 4-bromophenylmethyl, 2-fluorophenylmethyl, 3-fluorophenylmethyl, and 4-fluorophenylmethyl groups.

Specific examples of groups consisting of carbon atoms, hydrogen atoms, and oxygen atoms include hydroxyl chain alkyl groups such as hydroxymethyl groups, 2-hydroxyethyl groups, 3-hydroxy-n-propyl groups, and 4-hydroxy-n-butyl groups; halogenated cycloalkyl groups such as 2-hydroxycyclohexyl groups, 3-hydroxycyclohexyl groups, and 4-hydroxycyclohexyl groups; 2-hydroxyphenyl groups, 3-hydroxyphenyl groups, 4-hydroxyphenyl groups, 2,3-dihydroxyphenyl groups, 2,4-dihydroxyphenyl groups, 2,5-dihydroxyphenyl groups, hydroxyaryl groups such as 2-hydroxyphenylmethyl group, 3-hydroxyphenylmethyl group, and 4-hydroxyphenylmethyl group; hydroxyaralkyl groups such as 2-hydroxyphenylmethyl group, 3-hydroxyphenylmethyl group, and 4-hydroxyphenylmethyl group; methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butyloxy group, isobutyloxy group, sec-butyloxy group, tert-butyloxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, chain alkoxy groups such as an oxy group, a 2-ethylhexyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-tridecyloxy group, an n-tetradecyloxy group, an n-pentadecyloxy group, an n-hexadecyloxy group, an n-heptadecyloxy group, an n-octadecyloxy group, an n-nonadecyloxy group, and an n-icosyloxy group; a chain alkoxy group such as a vinyloxy group, a 1-propenyloxy group, a 2-n-propenyloxy group (allyloxy group), a 1-n-butenyloxy group, a 2-n-butenyloxy group, and a 3-n-butenyloxy group; chain alkenyloxy groups such as a phenyloxy group; aryloxy groups such as a phenoxy group, an o-tolyloxy group, an m-tolyloxy group, a p-tolyloxy group, an α-naphthyloxy group, a β-naphthyloxy group, a biphenyl-4-yloxy group, a biphenyl-3-yloxy group, a biphenyl-2-yloxy group, an anthryloxy group, and a phenanthryloxy group; aralkyloxy groups such as a benzyloxy group, a phenethyloxy group, an α-naphthylmethyloxy group, a β-naphthylmethyloxy group, an α-naphthylethyloxy group, and a β-naphthylethyloxy group; alkoxyalkyl groups such as an alkoxymethyl group, an ethoxymethyl group, an n-propoxymethyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, a 2-n-propoxyethyl group, a 3-methoxy-n-propyl group, a 3-ethoxy-n-propyl group, a 3-n-propoxy-n-propyl group, a 4-methoxy-n-butyl group, a 4-ethoxy-n-butyl group, and a 4-n-propoxy-n-butyl group; a methoxymethoxy group, an ethoxymethoxy group, an n-propoxymethoxy group, a 2-methoxyethoxy group, a 2-ethoxyethoxy group, a 2-n-propoxyethoxy group, Alkoxyalkoxy groups such as 3-methoxy-n-propoxy group, 3-ethoxy-n-propoxy group, 3-n-propoxy-n-propoxy group, 4-methoxy-n-butyloxy group, 4-ethoxy-n-butyloxy group, and 4-n-propoxy-n-butyloxy group; alkoxyaryl groups such as 2-methoxyphenyl group, 3-methoxyphenyl group, and 4-methoxyphenyl group; alkoxyaryloxy groups such as 2-methoxyphenoxy group, 3-methoxyphenoxy group, and 4-methoxyphenoxy group; formyl group, acetyl group, propionyl group, aliphatic acyl groups such as butanoyl, pentanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, and decanoyl groups; aromatic acyl groups such as benzoyl, α-naphthoyl, and β-naphthoyl groups; methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, n-butyloxycarbonyl, n-pentyloxycarbonyl, n-hexylcarbonyl, n-heptyloxycarbonyl, n-octyloxycarbonyl, n-nonyloxycarbonyl, and n-decyloxycarbonyl groups. chain alkyloxycarbonyl groups such as the group; aryloxycarbonyl groups such as the phenoxycarbonyl group, the α-naphthoxycarbonyl group, and the β-naphthoxycarbonyl group; aliphatic acyloxy groups such as the formyloxy group, the acetyloxy group, the propionyloxy group, the butanoyloxy group, the pentanoyloxy group, the hexanoyloxy group, the heptanoyloxy group, the octanoyloxy group, the nonanoyloxy group, and the decanoyloxy group; and aromatic acyloxy groups such as the benzoyloxy group, the α-naphthoyloxy group, and the β-naphthoyloxy group.

It is preferable that R ^b01 to R ^b018 are each independently a group selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having from 1 to 5 carbon atoms, and an alkoxy group having from 1 to 5 carbon atoms. It is more preferable that R ^b01 to R ^b018 are all hydrogen atoms, as this makes it easier to form a cured film having particularly excellent mechanical properties.

In formulas (b01-2) to (b01-5), R ^b01 to R ^b018 are the same as R ^b01 to R ^b018 in formula (b01-1). Examples of the divalent group formed when R ^b02 and R ^b010 are bonded to each other in formula (b01-2) and formula (b01-4), when R ^b013 and R ^b016 are bonded to each other in formula (b01-2), and when R ^b02 and R ^b08 are bonded to each other in formula (b01-3) include -CH ₂ - and -C(CH ₃ ) ₂ -.

Among the alicyclic epoxy compounds represented by formula (b01-1), specific examples of suitable compounds include alicyclic epoxy compounds represented by the following formulas (b01-1a), (b01-1b), and (b01-1c), 2,2-bis(3,4-epoxycyclohexyl-1-yl)propane [=2,2-bis(3,4-epoxycyclohexyl)propane], and the like.

Among the alicyclic epoxy compounds represented by formula (b01-2), specific examples of suitable compounds include alicyclic epoxy compounds represented by the following formulas (b01-2a) and (b01-2b).

Of the alicyclic epoxy compounds represented by formula (b01-3), specific examples of suitable compounds include S spiro[3-oxatricyclo[3.2.1.0 ^2,4 ]octane-6,2′-oxirane].

Specific examples of suitable compounds among the alicyclic epoxy compounds represented by formula (b01-4) include 4-vinylcyclohexene dioxide, dipentene dioxide, limonene dioxide, 1-methyl-4-(3-methyloxiran-2-yl)-7-oxabicyclo[4.1.0]heptane, etc.

Among the alicyclic epoxy compounds represented by formula (b01-5), specific examples of suitable compounds include 1,2,5,6-diepoxycyclooctane, etc.

（式（ｂ１－Ｉ）中、Ｘ^ｂ１、Ｘ^ｂ２、及びＸ^ｂ３は、それぞれ独立に、水素原子、又はエポキシ基を含んでいてもよい有機基であり、Ｘ^ｂ１、Ｘ^ｂ２、及びＸ^ｂ３が有するエポキシ基の総数が２以上である。） Furthermore, a compound represented by the following formula (b1-I) can be suitably used as the epoxy compound.

(In formula (b1-I), X ^b1 , X ^b2 , and X ^b3 each independently represent a hydrogen atom or an organic group which may contain an epoxy group, and the total number of epoxy groups contained in X ^b1 , X ^b2 , and X ^b3 is 2 or more.)

（式（ｂ１－ＩＩ）中、Ｒ^ｂ２０～Ｒ^ｂ２２は、直鎖状、分岐鎖状又は環状のアルキレン基、アリーレン基、－Ｏ－、－Ｃ（＝Ｏ）－、－ＮＨ－及びこれらの組み合わせからなる基であり、それぞれ同一であってもよいし、異なっていてもよい。Ｅ^１～Ｅ^３は、エポキシ基、オキセタニル基、エチレン性不飽和基、アルコキシシリル基、イソシアネート基、ブロックイソシアネート基、チオール基、カルボキシ基、水酸基及びコハク酸無水物基からなる群より選択される少なくとも１種の置換基又は水素原子である。ただし、Ｅ^１、Ｅ^２、及びＥ^３が有するエポキシ基の総数が２以上である。） As the compound represented by the above formula (b1-I), a compound represented by the following formula (b1-II) is preferable.

(In formula (b1-II), R ^b20 to R ^b22 each represent a linear, branched or cyclic alkylene group, an arylene group, -O-, -C(=O)-, -NH-, or a group consisting of a combination thereof, and may be the same or different. E ¹ to E ³ each represent at least one substituent selected from the group consisting of an epoxy group, an oxetanyl group, an ethylenically unsaturated group, an alkoxysilyl group, an isocyanate group, a blocked isocyanate group, a thiol group, a carboxy group, a hydroxyl group, and a succinic anhydride group, or a hydrogen atom, provided that the total number of epoxy groups owned by E ¹ , E ² , and E ³ is 2 or more.)

In formula (b1-II), for example, at least two of the groups represented by R ^b20 and E ¹ , R ^b21 and E ² , and R ^b22 and E ³ are preferably groups represented by the following formula (b1-IIa), and it is more preferable that all of them are groups represented by the following formula (b1-IIa). It is preferable that multiple groups represented by formula (b1-IIa) bonded to one compound are the same group.
-LC ^a (b1-IIa)
(In formula (b1-IIa), L is a linear, branched or cyclic alkylene group, an arylene group, -O-, -C(=O)-, -NH- or a group consisting of a combination thereof, and C ^a is an oxiranyl group (epoxy group). In formula (b1-IIa), L and C ^a may be bonded to form a cyclic structure.)

In formula (b1-IIa), the linear, branched or cyclic alkylene group represented by L is preferably an alkylene group having 1 to 10 carbon atoms, and the arylene group represented by L is preferably an arylene group having 5 to 10 carbon atoms. In formula (b1-IIa), L is preferably a linear alkylene group having 1 to 3 carbon atoms, a phenylene group, -O-, -C(=O)-, -NH-, or a group consisting of a combination thereof, and is preferably at least one of a linear alkylene group having 1 to 3 carbon atoms, such as a methylene group, and a phenylene group, or a group consisting of a combination of these with at least one of -O-, -C(=O)-, and NH-.

（式（ｂ１－ＩＩｂ）中、Ｒ^ｂ２３は、水素原子又はメチル基である。） In formula (b1-IIa), examples of the case where L and C ^a are bonded to form a cyclic structure include, for example, the case where a branched alkylene group and an epoxy group are bonded to form a cyclic structure (a structure having an epoxy group of an alicyclic structure), organic groups represented by the following formulas (b1-IIb) to (b1-IId) can be mentioned.

(In formula (b1-IIb), R ^b23 is a hydrogen atom or a methyl group.)

Examples of the compound represented by formula (b1-II) include, but are not limited to, epoxy compounds having an oxiranyl group or an alicyclic epoxy group.

In addition, a siloxane compound having two or more glycidyl groups in the molecule (hereinafter, simply referred to as a "siloxane compound") can be suitably used as the epoxy compound.

A siloxane compound is a compound that has a siloxane skeleton composed of siloxane bonds (Si-O-Si) and two or more glycidyl groups in the molecule.

Examples of the siloxane skeleton in the siloxane compound include a cyclic siloxane skeleton and a cage-type or ladder-type polysilsesquioxane skeleton.

As the siloxane compound, a compound having a cyclic siloxane skeleton represented by the following formula (b1-III) (hereinafter, sometimes referred to as "cyclic siloxane") is preferable.

In formula (b1-III), R ^b24 and R ^b25 represent a monovalent group or alkyl group containing an epoxy group. However, of the x1 R ^b24s and the x1 R ^b25s in the compound represented by formula (b1-III), at least two are monovalent groups containing an epoxy group. Furthermore, x1 in formula (b1-III) represents an integer of 3 or more. Note that R ^b24 and R ^b25 in the compound represented by formula (b1-III) may be the same or different. Furthermore, multiple R ^b24s may be the same or different. Multiple R ^b25s may also be the same or different.
Examples of the alkyl group include linear or branched alkyl groups having 1 or more and 18 or less carbon atoms (preferably 1 or more and 6 or less carbon atoms, particularly preferably 1 or more and 3 or less carbon atoms), such as a methyl group, an ethyl group, a propyl group, or an isopropyl group.

In formula (b1-III), x1 represents an integer of 3 or more, and in particular, an integer of 3 or more and 6 or less is preferred in terms of excellent crosslinking reactivity when forming a cured film.
The number of epoxy groups contained in the siloxane compound in the molecule is 2 or more, and from the viewpoint of excellent crosslinking reactivity when forming a cured film, 2 to 6 is preferable, and 2 to 4 is particularly preferable.

（上記式（ｂ１－ＩＩＩａ）及び式（ｂ１－ＩＩＩｂ）中、Ｄ^１及びＤ^２は、それぞれ独立にアルキレン基を表し、ｍｓは０以上２以下の整数を表す。） The monovalent group containing an epoxy group is preferably an alicyclic epoxy group or a glycidyl ether group represented by -D ^A -O-R ^b26 [D ^A represents an alkylene group and R ^b26 represents a glycidyl group], more preferably an alicyclic epoxy group, and even more preferably an alicyclic epoxy group represented by the following formula (b1-IIIa) or (b1-IIIb). Examples of D ^A (alkylene group) include linear or branched alkylene groups having 1 to 18 carbon atoms, such as a methylene group, a methylmethylene group, a dimethylmethylene group, a dimethylene group, and a trimethylene group.

(In the above formula (b1-IIIa) and formula (b1-IIIb), ^D1 and D2 ^each independently represent an alkylene group, and ms represents an integer of 0 to 2.)

In addition to the siloxane compound represented by formula (b1-III), the varnish composition may contain, as an epoxy compound, a compound having a siloxane skeleton, such as an alicyclic epoxy group-containing cyclic siloxane, an alicyclic epoxy group-containing silicone resin described in JP-A-2008-248169, and an organopolysilsesquioxane resin having at least two epoxy functional groups in one molecule described in JP-A-2008-19422.

Specific examples of siloxane compounds include cyclic siloxanes having two or more glycidyl groups in the molecule, as represented by the following formula. In addition, examples of siloxane compounds that can be used include commercially available products under the trade names "X-40-2670", "X-40-2701", "X-40-2728", "X-40-2738", and "X-40-2740" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

The content of the monomer compound (B) in the varnish composition is not particularly limited as long as it does not impair the object of the present invention. The content of the monomer compound (B) in the varnish composition is preferably 0.1 parts by mass or more and 50 parts by mass or less, more preferably 0.5 parts by mass or more and 40 parts by mass or less, and particularly preferably 1 part by mass or more and 25 parts by mass or less, when the mass of the varnish composition excluding the mass of the solvent (S) described below is taken as 100 parts by mass.

The varnish composition preferably contains a photoinitiator (C). When the polyimide resin (A) has a radical polymerizable group, a photoradical polymerization initiator (C1) may be used as the photoinitiator (C). When the polyimide resin (A) has a cationic polymerizable group, a photocationic polymerization initiator (C2) may be used as the photoinitiator (C).
The photoinitiator (C) is not particularly limited, and any conventionally known photopolymerization initiator can be used.

Specific examples of the photoradical polymerization initiator (C1) include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, bis(4-dimethylaminophenyl)ketone, 2-methyl-1-[4-(methylthio)phenyl]- 2-Morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, O-acetyl-1-[6-(2-methylbenzoyl)-9-ethyl-9H-carbazol-3-yl]ethanone oxime, (9-ethyl-6-nitro-9H-carbazol-3-yl)[4-(2-methoxy-1-methylethoxy)-2-methylphenyl]methanone O-acetyl oxime, 2-(benzoyloxyimino)-1-[4-(phenylthio)phenyl]-1-octanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 4-benzoyl-4'- Methyl dimethyl sulfide, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, butyl 4-dimethylaminobenzoate, 4-dimethylamino-2-ethylhexylbenzoic acid, 4-dimethylamino-2-isoamylbenzoic acid, benzyl-β-methoxyethyl acetal, benzyl dimethyl ketal, 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime, methyl o-benzoylbenzoate, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 1-chloro-4-propoxythioxanthone , thioxanthene, 2-chlorothioxanthene, 2,4-diethylthioxanthene, 2-methylthioxanthene, 2-isopropylthioxanthene, 2-ethylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-diphenylanthraquinone, azobisisobutyronitrile, benzoyl peroxide, cumene hydroperoxide, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)-imidazolyl dimer, benzophenone, 2-chlorobenzophenone , p,p'-bisdimethylaminobenzophenone, 4,4'-bisdiethylaminobenzophenone, 4,4'-dichlorobenzophenone, 3,3-dimethyl-4-methoxybenzophenone, benzil, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, benzoin butyl ether, acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, dichloroacetophenone, trichloroacetophenone, p-tert-butylacetophenone tophenone, p-dimethylaminoacetophenone, p-tert-butyltrichloroacetophenone, p-tert-butyldichloroacetophenone, α,α-dichloro-4-phenoxyacetophenone, thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, dibenzosuberone, pentyl-4-dimethylaminobenzoate, 9-phenylacridine, 1,7-bis-(9-acridinyl)heptane, 1,5-bis-(9-acridinyl)pentane, 1,3-bis-(9-acridinyl)propane, p-methoxytriazine, 2,4,6-tris(trichloromethyl)-s-triazine, 2-methyl-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(5-methylfuran-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(furan-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(4-diethylamino-2-methylphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(3,4-dimethoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, Examples include 2-(4-ethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-n-butoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis-trichloromethyl-6-(3-bromo-4-methoxy)phenyl-s-triazine, 2,4-bis-trichloromethyl-6-(2-bromo-4-methoxy)phenyl-s-triazine, 2,4-bis-trichloromethyl-6-(3-bromo-4-methoxy)styrylphenyl-s-triazine, and 2,4-bis-trichloromethyl-6-(2-bromo-4-methoxy)styrylphenyl-s-triazine. These photopolymerization initiators can be used alone or in combination of two or more.

Typical examples of the cationic photopolymerization initiator (C2) include onium salts. Examples of the cationic photopolymerization initiator (C2) include oxonium salts, ammonium salts, phosphonium salts, sulfonium salts, and iodonium salts, with sulfonium salts and iodonium salts being preferred, and sulfonium salts being more preferred.

The content of the photoinitiator (C) in the varnish composition is not particularly limited as long as the varnish composition has the desired photolithography properties. The content of the photoinitiator (C) in the varnish composition is typically preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the total of the mass of the polyimide resin (A) and the mass of the monomer compound (B).

The varnish composition contains an organic solvent (S). The type of organic solvent (S) is not particularly limited as long as it satisfactorily dissolves the polyimide resin (A) and other components.
In view of good solubility of the polyimide resin (A), the organic solvent (S) preferably contains one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N-diethylformamide, N-methylcaprolactam, N,N,N',N'-tetramethylurea, cyclopentanone, and cyclohexanone.
The content of these preferable organic solvents in the organic solvent (S) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass.

The varnish composition may contain various additives other than the components described above, as necessary. Examples of additives include colorants, dispersants, sensitizers, adhesion promoters, antioxidants, UV absorbers, anti-aggregation agents, defoamers, surfactants, etc. In addition, the varnish composition may contain various fillers or reinforcing materials, as necessary.
The amount of each additive used is not particularly limited as long as it does not impair the object of the present invention. It may be appropriately adjusted within a range of, for example, 0.001% by mass to 60% by mass, preferably 0.05% by mass to 5% by mass, based on the mass of the solid content of the varnish composition.
The amount of the filler or reinforcing material used is not particularly limited as long as it does not impair the object of the present invention. The amount of the filler or reinforcing material used is typically preferably 1 mass% or more and 300 mass% or less, more preferably 5 mass% or more and 200 mass% or more, and even more preferably 10 mass% or more and 100 mass% or less, based on the mass of the polyamic acid (A).

<Production method of polyimide film>
The varnish composition described above is applied onto a desired substrate to form a coating film, and then at least a portion of the organic solvent (S) is removed from the coating film to form a polyimide film.
That is, a coating step of applying the varnish composition onto a substrate to form a coating film;
an organic solvent removing step of removing at least a part of the organic solvent (S) from the coating film;
The polyimide film is produced by a method comprising the steps of:

The method for applying the varnish composition onto the substrate is not particularly limited. For example, the varnish composition can be applied to the substrate to a desired thickness using a contact transfer type application device such as a roll coater, reverse coater, bar coater, or slit coater, or a non-contact type application device such as a spinner (rotary application device) or curtain flow coater, to form a coating film.

After forming a coating film made of the varnish composition by the above method, the coating film is baked to remove the organic solvent (S) to form a polyimide film. The baking temperature is appropriately determined taking into consideration the boiling point of the organic solvent (S) and the heat resistance of the polyimide resin. Baking may be performed at a low temperature under reduced pressure.

The baking method is not particularly limited, and may be, for example, any of the following: (i) drying using a hot plate at a temperature of 80°C to 120°C (preferably 85°C to 100°C, more preferably 85°C to 95°C) for 60 to 500 seconds; (ii) leaving at room temperature for several hours to several days; or (iii) placing the substrate in a hot air heater or infrared heater for several tens of minutes to several hours to remove the organic solvent (S).

The coating film formed as described above may be post-baked after removing the organic solvent (S). The upper limit of the temperature for post-baking is, for example, preferably 300° C. or less, and more preferably 280° C. or less. The lower limit of the temperature is preferably 120° C. or more, and more preferably 130° C. or more.

The thickness of the polyimide film formed in the above manner is not particularly limited and is determined appropriately depending on the application. The thickness of the polyimide film is typically preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

When the varnish composition contains a photoinitiator (C), a patterned polyimide film can be obtained by forming a coating film by the above-mentioned method, and then exposing and developing the coating film.
That is, a coating step of coating a substrate with a varnish composition containing a photoinitiator (C) to form a coating film;
an organic solvent removing step of removing at least a part of the organic solvent (S) from the coating film;
a patterning step of exposing and developing the coating film from which at least a portion of the organic solvent (S) has been removed;
A patterned polyimide film is produced by a method comprising:

In the above-mentioned method for producing a patterned polyimide film, the application of the varnish composition and the heating of the applied film to remove the organic solvent (S) are carried out according to the above-mentioned method.

The conditions for exposing the varnish composition are not particularly limited as long as the curing proceeds well. The exposure is carried out by irradiating with active energy rays such as ultraviolet rays and excimer laser light. The amount of energy radiation to be irradiated is not particularly limited, but may be, for example, 30 mJ/ ^cm2 or more and 5000 mJ/ ^cm2 or less. After exposure, the exposed coating film may be baked by the same method as heating after coating.

The developing method is not particularly limited, and for example, a dipping method, a spray method, etc. can be used. A specific example of the developing solution is an organic solvent (S) that may be contained in the varnish composition.

After development, the developed coating film is rinsed with pure water or baked, if necessary, to obtain a patterned polyimide film.
The post-development baking conditions are, for example, preferably from 150° C. to 280° C., and more preferably from 180° C. to 230° C. The post-development baking time is, for example, preferably from 5 minutes to 12 hours, more preferably from 10 minutes to 6 hours, and particularly preferably from 30 minutes to 1 hour.

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to these examples.

Example 1
Into a three-neck flask, 15.57 g of 4,4'-(4-aminophenyloxy)biphenyl (hereinafter referred to as BPAB) as a diamine component, 6.43 g of 3,5-diaminobenzoic acid (hereinafter referred to as DABA), and 250 g of NMP were added. Next, the contents of the flask were stirred to dissolve BPAB and DABA in NMP. Then, 40 g of 2,2-bis[4-(3,4-dicarboxyphenyloxy)phenyl]propane dianhydride (hereinafter referred to as BPADA) as a tetracarboxylic dianhydride component was added to the solution in the flask, and the reaction solution in the flask was stirred at room temperature for 24 hours. Then, 0.88 g of 5-norbornene-2,3-dicarboxylic anhydride was added to the reaction solution as an end-capping agent, and the reaction solution was stirred at room temperature for 4 hours to obtain a polyamic acid.
In addition, the numerical values in the parentheses to the right of the following formulas indicate the molar ratios (mol %) of each structural unit in the resin.

<Polyamic acid production>

33 g of carbodiimidazole was added to the reaction solution containing the polyamic acid, and the reaction solution was stirred at room temperature for 4 hours to convert the polyamic acid into a polyimide resin.
The reaction solution after stirring was dropped into 5 kg of water to generate a precipitate. The generated precipitate was collected by filtration. The collected precipitate was washed three times with 2 kg of water and then dried under reduced pressure at 50° C. to obtain a polyimide resin having a carboxy group, which is composed of a structural unit in the following formula:

<Imidization>

The obtained polyimide resin having a carboxy group, 8.25 g of 2-hydroxyethyl methacrylate, 25.0 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (WSC-HCl), and 5.15 g of 4-dimethylaminopyridine (DMAP) were added to 250 g of NMP in a three-neck flask, and the reaction solution was stirred at room temperature for 6 hours.
The reaction solution after stirring was dropped into 2 kg of methanol to generate a precipitate. The generated precipitate was collected by filtration. The collected precipitate was washed three times with 2 kg of methanol and then dried under reduced pressure at 50°C to obtain a polyimide resin having a methacryloyl group at the side chain end, which is composed of the structural unit shown in the following formula.
The obtained polyimide resin was subjected to ¹ H-NMR measurement. The imidization was confirmed by the disappearance of the peak corresponding to the amide bond, and the introduction of the theoretical amount of methacryloyl groups into the polyimide resin was confirmed from the integral ratio of all aromatics and the integral ratio of double bonds.

<Introduction of methacryloyl group>

Example 2
A polyimide resin having the following structure was synthesized in the same manner as in Example 1, except that the amount of BPAB used was changed to 21.80 g, the amount of DABA used was changed to 3.86 g, and the amount of 2-hydroxyethyl methacrylate used was changed to 4.95 g.
The obtained polyimide resin was subjected to ¹ H-NMR measurement. The imidization was confirmed by the disappearance of the peak corresponding to the amide bond, and the introduction of the theoretical amount of methacryloyl groups into the polyimide resin was confirmed from the integral ratio of all aromatics and the integral ratio of double bonds.

Example 3
A polyimide resin having the following structure was synthesized in the same manner as in Example 1, except that the amount of BPAB used was changed to 24.19 g, the amount of DABA used was changed to 2.57 g, and the amount of 2-hydroxyethyl methacrylate used was changed to 3.30 g.
The obtained polyimide resin was subjected to ¹ H-NMR measurement. The imidization was confirmed by the disappearance of the peak corresponding to the amide bond, and the introduction of the theoretical amount of methacryloyl groups into the polyimide resin was confirmed from the integral ratio of all aromatics and the integral ratio of double bonds.

Example 4
A polyimide resin having the structure shown below was synthesized in the same manner as in Example 1, except that 15.57 g of BPAB was changed to 19.18 g of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (hereinafter referred to as TFDB), the amount of DABA used was changed to 3.86 g, the amount of 2-hydroxyethyl methacrylate used was changed to 4.95 g, and the amount of WSC-HCl used was changed to 13.62 g.
The obtained polyimide resin was subjected to ¹ H-NMR measurement. The imidization was confirmed by the disappearance of the peak corresponding to the amide bond, and the introduction of the theoretical amount of methacryloyl groups into the polyimide resin was confirmed from the integral ratio of all aromatics and the integral ratio of double bonds.

Example 5
A polyimide resin having the structure of the following formula was synthesized in the same manner as in Example 1, except that 15.57 g of BPAB was changed to 30.68 g of 2,2-bis[4-(4-aminophenyloxy)phenyl]-1,1,1,3,3,3-hexafluorophenylpropane (HF-BPAA below), the amount of DABA used was changed to 3.86 g, the amount of 2-hydroxyethyl methacrylate used was changed to 4.95 g, and the amount of WSC-HCl used was changed to 13.62 g.
The obtained polyimide resin was subjected to ¹ H-NMR measurement. The imidization was confirmed by the disappearance of the peak corresponding to the amide bond, and the introduction of the theoretical amount of methacryloyl groups into the polyimide resin was confirmed from the integral ratio of all aromatics and the integral ratio of double bonds.

Example 6
40 g of BPADA was changed to 40 g of 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride (hereinafter referred to as 6FDA), 15.57 g of BPAB was changed to 35.94 g of HF-BPAA, the amount of DABA used was changed to 4.52 g, the amount of carbodiimidazole used was changed to 28.17 g, the amount of 2-hydroxyethyl methacrylate used was changed to 5.80 g, and the amount of WSC-HCl used was changed to 15.95 g. A polyimide resin having the structure of the following formula was synthesized in the same manner as in Example 1.

Example 7
A polyimide resin having the structure of the following formula was synthesized in the same manner as in Example 1, except that 40 g of BPADA was changed to 40 g of 3,3',4,4'-tetracarboxydiphenylether dianhydride (hereinafter referred to as ODPA), 15.57 g of BPAB was changed to 51.47 g of HF-BPAA, the amount of DABA used was changed to 6.47 g, the amount of carbodiimidazole used was changed to 28.17 g, the amount of 2-hydroxyethyl methacrylate used was changed to 5.80 g, and the amount of WSC-HCl used was changed to 15.95 g.

Example 8
24.91 g of BPAB as a diamine component, 5.89 g of 2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, and 250 g of NMP were added to a three-neck flask. The contents of the flask were then stirred to dissolve the diamine component in the NMP. Thereafter, 40 g of BPADA was added to the solution in the flask, and the reaction solution in the flask was stirred at room temperature for 24 hours to produce a polyamic acid.

<Polyamic acid production>

33 g of carbodiimidazole was added to the reaction solution containing the polyamic acid, and the reaction solution was stirred at room temperature for 4 hours to convert the polyamic acid into a polyimide resin.
The reaction solution after stirring was dropped into 5 kg of water to generate a precipitate. The generated precipitate was collected by filtration. The collected precipitate was washed three times with 2 kg of water and then dried under reduced pressure at 50° C. to obtain a polyimide resin having a phenolic hydroxyl group, which is composed of the structural unit in the following formula:

<Imidization>

The obtained polyimide resin having a phenolic hydroxyl group, 5.30 g of methacrylic acid chloride, 4.50 g of triethylamine, and 300 g of NMP were added to a three-neck flask, and the reaction solution in the flask was stirred at room temperature for 6 hours.
The reaction solution after stirring was dropped into 2 kg of methanol to generate a precipitate. The generated precipitate was collected by filtration. The collected precipitate was washed three times with 2 kg of methanol and then dried under reduced pressure at 50°C to obtain a polyimide resin having a methacryloyl group at the side chain end, which is composed of the structural unit shown in the following formula.
The obtained polyimide resin was subjected to ¹ H-NMR measurement. The imidization was confirmed by the disappearance of the peak corresponding to the amide bond, and the introduction of the theoretical amount of methacryloyl groups into the polyimide resin was confirmed from the integral ratio of all aromatics and the integral ratio of double bonds.

<Introduction of methacryloyl group>

Comparative Example 1
A polyimide resin having the structure shown below was synthesized in the same manner as in Example 1, except that 40 g of BPADA was changed to 40 g of 6FDA, 15.57 g of BPAB was changed to 22.48 g of TFDB, the amount of DABA used was changed to 4.52 g, the amount of carbodiimidazole used was changed to 28.17 g, the amount of 2-hydroxyethyl methacrylate used was changed to 5.80 g, and the amount of WSC-HCl used was changed to 15.95 g.

Comparative Example 2
A photosensitive polyamide resin consisting of the following structural units was obtained by the same method as in Synthesis Example 1 described in WO 2018/003726. The following polyamide resin generates a polyimide resin by ring closure accompanied by elimination of 2-hydroxyethyl methacrylate when heated.

[Examples 9 to 19, Comparative Example 3, or Comparative Example 4]
100 parts by mass of a polyimide resin or polyamide resin of the type shown in Table 1 was dissolved in NMP to a concentration of 20% by mass. 5 parts by mass of Irgacure OXE01 (manufactured by BASF Japan Ltd.), which is an oxime ester-based photopolymerization initiator, and 0.5 parts by mass of pentaerythritol tetrakis(3-mercaptobutyrate) (Karenz MT PE1 (manufactured by Showa Denko K.K.)), which is a chain transfer agent, were added to the obtained solution to obtain a photosensitive composition of each Example.
To the photosensitive compositions of Examples 12 to 14, photopolymerizable monomers of the types and amounts shown in Table 1 were further added. The photopolymerizable monomers shown in Table 1 are as follows.
M1: Dimethyloltricyclodecane diacrylate M2: Dipentaerythritol hexaacrylate

Using the obtained photosensitive composition, the imidization rate when made into a film, the photosensitivity, and the dielectric properties were evaluated by measuring the dielectric properties according to the following methods. The results of the photosensitivity evaluation and the dielectric properties evaluation are shown in Table 1.

<Film Formation and Imidization Rate Evaluation>
For Examples 9 to 19 and Comparative Example 3, the photosensitive composition was applied onto a silicon wafer by a spin coater, and the formed coating film was then exposed to a high-pressure mercury lamp at an exposure dose of 2000 mJ/ ^cm2 . The exposed coating film was heated at 180°C for 1 hour to form a polyimide resin film. The formed polyimide resin film was peeled off from the silicon wafer using an aqueous solution of hydrofluoric acid with a concentration of 1% by mass to obtain a polyimide resin film. The film thickness of the obtained polyimide resin film was 20 μm.

The imidization rate of the polyimide resin films obtained by the above-mentioned method using the NMP solutions of the polyimide resins obtained in Examples 9 to 19 and Comparative Example 3 was 95% or more.
For the photosensitive composition of Comparative Example 4 containing the photosensitive polyamide resin obtained in Comparative Example 2, an imidization rate of 95% or more could not be achieved by exposure under the above conditions and heating at 180°C for 1 hour, but an imidization rate of 95% or more was achieved by further heating at 350°C for 1 hour.
The imidization rate was measured by the following method. First, the film obtained by the above method was heated at 350°C for 4 hours, and then the FT-IR spectrum of the heated film was measured. Next, the FT-IR spectrum of the film obtained by the above method that was not heated at 350°C was measured.
The FT-IR spectrum of the film heated at 350° C. showed that the imide stretching vibration peak height H ⁰¹ at a wave number of 1380 cm ⁻¹ and the aromatic peak height H ⁰² were both measured, and the ratio H ⁰¹ /H ⁰² was calculated from these values.
Next, the ratio H 11 /H ¹² was calculated from the height H ¹¹ of the imide stretching vibration peak at a wave number of 1380 cm ^-1 and the height H ¹² of the aromatic peak in the FT-IR spectrum of the film not heated at ³⁵⁰ ° C.
The imidization rate was calculated from the value of H ⁰¹ /H ⁰² and the value of H ¹¹ /H ¹² according to the following formula.
Imidization rate (%)=(H ¹¹ /H ¹² )/(H ⁰¹ /H ⁰² )×100

<Photosensitivity Evaluation>
The coating film formed on the copper wafer by spin-coating the photosensitive composition was baked for 300 seconds at 80° C. The rotation speed during spin-coating was adjusted so that the coating film after baking had a thickness of 10 μm.
The baked coating film was exposed to light through a negative mask for hole formation having a substantially square opening of 50 μm×50 μm at a dose of 100 mJ/cm ² to 4000 mJ/cm ² with a focus of 0 μm.
The exposed coating film was developed by immersing it in cyclopentanone for 60 seconds.
The coating film after development was observed with a scanning electron microscope (SEM). If a hole having an approximately square opening measuring 50 μm × 50 μm was formed, it was judged as ◯, and if not, it was judged as ×.

<Dielectric property measurement>
The film obtained in the same manner as the above-mentioned film formation except for changing the film thickness to 10 μm was used as a sample, and the dielectric constant (ε) and dielectric tangent (tan δ) of the sample were measured by the method described in "Study on evaluation of millimeter-wave complex dielectric constant of photosensitive insulating film by cylindrical cavity resonator method" (Takahagi Kohei (Utsunomiya University), Ebisawa Kazuaki (Tokyo Ohka Kogyo Co., Ltd.), Kogami Yoshinori (Utsunomiya University), Shimizu Takashi (Utsunomiya University)) in IEICE Technical Report vol. 118, no. 506, MW2018-158, pp. 13-18, March 2019. Using a network analyzer HP8510C (Keysight Corporation), the measurement was performed by the cavity resonator method under the conditions of room temperature 25 ° C, humidity 50%, frequency 36 GHz, and sample thickness 10 μm.
The dielectric constant value was judged as ◯ when it was less than 3.00, and was judged as x when it was 3.00 or more.
A dielectric loss tangent value of less than 0.01 was judged as ◯, and a dielectric loss tangent value of 0.01 or more was judged as x.

According to Examples 9 to 11, it can be seen that a polyimide resin containing a structural unit of a specific structure represented by the above-mentioned formula (A1a) and having a polymerizable group such as a methacryloyl group dissolves well in an organic solvent such as NMP, exhibits good photosensitivity, and gives a polyimide resin film having excellent dielectric properties.
On the other hand, according to Comparative Examples 3 and 4, it is seen that a polyimide resin that does not contain a structural unit having the specific structure represented by the above-mentioned formula (A1), even if it has a polymerizable group, gives a polyimide resin film having inferior dielectric properties.

Claims (13)

A varnish composition comprising a polyimide resin (A) and an organic solvent (S),
The polyimide resin (A) is
The following formula (A1a):

(In formula (A1a), ^X1 is a divalent organic group, and ^Y1 is a tetravalent organic group. However, ^X1 does not include a divalent organic group having a polyorganosiloxane structure or a structure derived from dimer diamine, and ^Y1 does not include a tetravalent organic group having a sulfonyl group (—SO ₂ —).)
The molecular chain includes a structural unit represented by
At least one of the divalent organic group as ^X1 and the tetravalent organic group as ^Y1 is represented by the following formula (a1):

(In formula (a1), R ^a1 and R ^a2 each independently represent an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, or a halogen atom; n1 and n2 each independently represent an integer of from 0 to 4; R ^a3 and R ^a4 each independently represent a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, a halogenated alkyl group having from 1 to 4 carbon atoms, or a phenyl group; and R ^a3 and R ^a4 may be bonded to each other to form a ring.)
or
or a molecular chain including a structural unit represented by formula (A1a)
The following formula (A1e):

(In formula (A1e), ^X4 is a divalent organic group not having the partial structure represented by formula (a1), and ^Y2 is a tetravalent organic group not having the partial structure represented by formula (a1). However, ^X4 does not include a divalent organic group having a polyorganosiloxane structure or a structure derived from dimer diamine, and ^Y2 does not include a tetravalent organic group having a sulfonyl group (—SO ₂ —).)
A molecular chain including a constitutional unit represented by
having
The constitutional unit represented by the formula (A1e) does not have a partial structure represented by the formula (a1),
The varnish composition for pattern formation, wherein the molecular chain contains a radically polymerizable group. The molecular chain contains, as the constitutional unit represented by formula (A1a), the constitutional unit represented by the following formula (A1b):

(In formula (A1b), ^X2 and ^X3 each independently represent a divalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom; ^Y2 represents a tetravalent organic group which does not have the partial structure represented by formula (a1); and R ^a1 , R ^a2 , R ^a3 , R ^a4 , n1, and n2 are the same as those in formula (a1).)
A structural unit represented by the following formula (A1c):

(In formula (A1c), ^X4 is a divalent organic group not having the partial structure represented by formula (a1), ^Y3 and ^Y4 are each independently a trivalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom, and R ^a1 , R ^a2 , R ^a3 , R ^a4 , n1, and n2 are the same as those in formula (a1).)
and a structural unit represented by the following formula (A1d):

(In formula (A1d), ^X5 and ^X6 are each independently a divalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom; ^Y5 and ^Y6 are each independently a trivalent aromatic hydrocarbon group which may be substituted with one or more groups selected from the group consisting of an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, and a halogen atom; and R ^a1 , R ^a2 , R ^a3 , R ^a4 , n1, and n2 are the same as those in formula (a1).)
2. The pattern-forming varnish composition according to claim 1, comprising at least one structural unit selected from the group consisting of structural units represented by the following formula: The varnish composition for pattern formation according to claim 2, wherein the polyimide resin contains a constitutional unit represented by the formula (A1c), and the ^X4 has the radical polymerizable group. 4. The pattern-forming varnish composition according to claim 1, wherein the radical polymerizable group is a (meth)acryloyl group-containing group. Further comprising a monomer compound (B),
5. The varnish composition for pattern formation according to claim 1, wherein the monomer compound (B) is a monomer compound having an ethylenically unsaturated double bond. The varnish composition for pattern formation according to claim 5 , wherein the monomer compound (B) is a polyfunctional monomer compound. 7. The varnish composition for pattern formation according to claim 5 or 6, wherein the content of the monomer compound (B) is 0.1 parts by mass or more and 50 parts by mass or less when the mass of the varnish composition excluding the mass of the organic solvent (S) is 100 parts by mass. 8. The pattern-forming varnish composition according to claim 1 , wherein a ratio of the mass of the polyimide resin (A) to the mass of the varnish composition is 5 mass% or more and 50 mass% or less. 9. The varnish composition for pattern formation according to claim 1, wherein 80% by mass or more of the polyimide resin (A) is dissolved in the organic solvent (S) at 20° C. The varnish composition for pattern formation according to any one of claims 1 to 9, wherein the organic solvent (S) comprises one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N- diethylformamide , N-methylcaprolactam, N, N, N ',N'-tetramethylurea, cyclopentanone, and cyclohexanone. The pattern-forming varnish composition according to any one of claims 1 to 10 , further comprising a photoinitiator (C). A coating step of coating a substrate with the varnish composition for pattern formation according to any one of claims 1 to 11 to form a coating film;
an organic solvent removing step of removing at least a part of the organic solvent (S) from the coating film;
A method for producing a polyimide film, comprising: A coating step of applying the varnish composition for pattern formation according to claim 11 onto a substrate to form a coating film;
an organic solvent removing step of removing at least a part of the organic solvent (S) from the coating film;
a patterning step of exposing and developing the coating film from which at least a portion of the organic solvent (S) has been removed;
A method for producing a patterned polyimide film, comprising: