JP7437997B2 - Varnish composition, polyimide resin manufacturing method, and additives - Google Patents

Description

The present invention relates to a varnish composition, a method for producing a polyimide resin using the varnish composition, and additives suitably blended into a varnish composition for forming a polyimide resin.

Polyimide resin has properties such as excellent heat resistance, mechanical strength, insulation, and low dielectric constant, so it is used as an insulator in electrical and electronic components such as various elements and electronic boards such as multilayer wiring boards. It is widely used as wood and protection material.

Generally, a polyimide resin is formed by heat-treating a polyamic acid obtained by polymerizing a tetracarboxylic dianhydride component and a diamine component in a polar organic solvent. Against this background, polyimide products for electronic materials are often supplied as a solution of a polyimide precursor such as polyamic acid. Specifically, when manufacturing electrical/electronic parts, a solution of a polyimide precursor is supplied to the location where the insulating material or protective material is to be formed by a method such as coating or injection. is heat-treated to form insulating and protective materials.

Technological developments related to such polyimide resins have been intensively developed, and various resin compositions containing polyamic acid and the like have been disclosed (see, for example, Patent Document 1).

JP2018-58918A

However, with respect to the polyimide resin disclosed in Patent Document 1 and the like, there are further demands for improvement in physical properties such as thermal expansion coefficient, elongation at break, and tensile strength.

The present invention was made in view of the above problems, and provides a varnish composition that provides a polyimide resin with improved physical properties such as thermal expansion coefficient, elongation at break, and tensile strength, and uses the varnish composition. It is an object of the present invention to provide a method for producing a polyimide resin and an additive suitably used as a component of the above-mentioned varnish composition.

The present inventors solved the above problem by blending an amide compound (C) with a specific structure into a varnish composition for forming a polyimide resin containing a polyamic acid (A) and a solvent (S). We have discovered that this can be done, and have completed the present invention. More specifically, the present invention provides the following.

The first aspect of the present invention is
Contains a polyamic acid (A), an amide compound (C), and a solvent (S),
The amide compound (C) has the following formula (C1):
R ^c1 -(-CO-NH-R ^c2 ) _n ...(C1)
(In formula (C1), R ^c1 is an n-valent organic group bonded to a carbonyl group via a carbon-carbon bond, and R ^c2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. (n is an integer between 1 and 4.)
This is a varnish composition for forming polyimide resin, which is a compound represented by:

A second aspect of the present invention includes a molding step of molding the varnish composition according to the first aspect;
This is a method for producing a polyimide resin, including an imidization step of heating and imidizing a molded varnish composition.

The third aspect of the present invention is
An additive used to obtain a varnish composition for forming a polyimide resin by blending it into a polyamic acid-containing liquid containing a polyamic acid (A) and a solvent (S),
the additive contains an amide compound (C),
The amide compound (C) has the following formula (C1):
R ^c1 -(-CO-NH-R ^c2 ) _n ...(C1)
(In formula (C1), R ^c1 is an n-valent organic group bonded to a carbonyl group via a carbon-carbon bond, and R ^c2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. (n is an integer between 1 and 4.)
It is a compound represented by
When a polyimide resin is obtained by heating a varnish composition, the obtained polyimide resin has a lower coefficient of thermal expansion, an improved elongation at break, and a lower tensile strength than when a polyamic acid-containing liquid is heated to obtain a polyimide resin. An additive that produces at least one of the following:

According to the present invention, there is provided a varnish composition that provides a polyimide resin with improved physical properties such as thermal expansion coefficient, elongation at break, and tensile strength, a method for producing a polyimide resin using the varnish composition, and a method for producing a polyimide resin that uses the varnish composition. Additives suitably used as constituent components of the composition can be provided.

≪Varnish composition≫
The varnish composition includes a polyamic acid (A), an amide compound (C), and a solvent (S). The varnish composition is used to form a polyimide resin.
By containing the amide compound (C), the varnish composition can be used to form a polyimide resin with improved physical properties such as thermal expansion coefficient, elongation at break, and tensile strength. The amide compound (C) will be described in detail later.
Here, the term "improvement in the coefficient of thermal expansion" refers to an improvement in the dimensional stability of the polyimide resin due to a decrease in the coefficient of thermal expansion. Improvement in elongation at break is an increase in elongation at break. An improvement in tensile strength is an increase in tensile strength.

The essential or optional components of the varnish composition will be explained below.

<Polyamic acid (A)>
The varnish composition contains polyamic acid (A). Polyamic acid (A) is a precursor polymer of polyimide resin produced when the varnish composition is cured. The polyamic acid (A) is not particularly limited as long as it is a resin conventionally used as a precursor polymer in producing polyimide resins.

（式（ａ１）中、Ａ^１は炭素原子数６以上５０以下の４価の有機基であり、Ａ^２は２価の有機基である。） Polyamic acid (A) can usually be obtained by condensing a monomer component consisting of a tetracarboxylic dianhydride and a diamine compound.
The polyamic acid may have a structural unit represented by the following formula (a1).

(In formula (a1), A ¹ is a tetravalent organic group having 6 to 50 carbon atoms, and A ² is a divalent organic group.)

Hereinafter, the tetracarboxylic dianhydride, the diamine compound, and the method for producing polyamic acid (A), which are used for producing polyamic acid (A), will be described below.

（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。） [Tetracarboxylic dianhydride]
The tetracarboxylic dianhydride that produces the structural unit represented by formula (a1) is represented by the following formula (a1-1).
The tetracarboxylic dianhydride represented by formula (a1-1) reacts with a diamine compound described below to give a polyamic acid (A) having a structural unit represented by formula (a1). Such 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.)

In formula (a1-1), A ¹ is a tetravalent organic group having 6 to 50 carbon atoms, and is an acid represented by two -CO-O-CO- in formula (a1-1). In addition to the anhydride group, it may have one or more substituents.
Suitable examples of the substituent include 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, and a fluorinated alkyl group having 1 to 6 carbon atoms. A fluorinated alkoxy group of 1 or more and 6 or less is preferred. Further, the compound represented by formula (a1-1) may contain a carboxy group or a carboxylic acid ester 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.
Regarding the above substituents, the same can be said of one or more substituents that the aromatic group described below may have on the aromatic ring.

In formula (a1-1), A ¹ is a tetravalent organic group, and the lower limit of the number of carbon atoms is 6 and the upper limit is 50.
The number of carbon atoms constituting A ¹ is more preferably 8 or more, and even more preferably 12 or more. Further, 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 combination of 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, nitrogen atom, or sulfur atom, the oxygen atom, nitrogen atom, or sulfur atom is a nitrogen-containing heterocyclic group, -CONH-, -NH-, -N=N-, -CH= A ¹ may include a group selected from N-, -COO-, -O-, -CO-, -SO-, -SO ₂ -, -S-, and -S-S-, It is more preferable that A ¹ includes a group selected from -O-, -CO-, -SO-, -SO ₂ -, -S-, and -SS-.

The tetracarboxylic dianhydride can be appropriately selected from tetracarboxylic dianhydrides that have been conventionally used as raw materials for synthesizing polyamic acids. 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, bis(3,4-dicarboxy)methane dianhydride, and the like. Moreover, the aliphatic tetracarboxylic dianhydride may 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, a bridged alicyclic structure may be fused with another bridged alicyclic structure and/or a non-bridged alicyclic structure, or a bridged alicyclic structure may be fused with another bridged alicyclic structure and/or a non-bridged alicyclic structure. It may be connected to a formula structure and/or a non-bridged alicyclic structure by a spiro bond. When an aliphatic tetracarboxylic dianhydride is used, a polyimide resin with excellent transparency tends to be easily obtained using a varnish 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。） Further, as the aliphatic group constituting A ¹ in formula (a1-1), for example, a tetravalent group represented by the following formula (a2) can be employed. When such a group is used, there is a tendency to easily obtain a polyimide resin having excellent transparency.
In addition, from the viewpoint of easy purification of the raw material compound, a in formula (a2) is preferably 5 or less, more preferably 3 or less. Moreover, since the chemical stability of the raw material compound providing the structural unit represented by formula (a1) is excellent, a is preferably 1 or more, and 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 are each independently one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and a fluorine atom, a is an integer between 0 and 12.)

Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 3,3',4,4'-oxy Bisphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4, Examples include 4'-benzophenonetetracarboxylic dianhydride and 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride.

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

In formulas (a1-2) and (a1-3) above, R ^a1 , R ^a2 and R ^a3 each represent an aliphatic group optionally substituted with halogen, an oxygen atom, a sulfur atom, one or more It is either an aromatic group via a divalent element, or a divalent group constituted by a combination thereof. R ^a2 and R ^a3 may be the same or different.
That is, R ^a1 , R ^a2 and R ^a3 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. Examples include anhydrides.

Furthermore, in the above formula (a1-4), R ^a4 and R ^a5 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 combination thereof. R ^a4 and R ^a5 may be the same or different. As the compound represented by formula (a1-4), difluoropyromellitic dianhydride, dichloropyromellitic dianhydride, etc. can also be used.

Examples of the tetracarboxylic dianhydride for obtaining a fluorine-containing polyimide containing fluorine in its molecular structure include (trifluoromethyl)pyromellitic dianhydride and di(trifluoromethyl)pyromellitic dianhydride. , di(heptafluoropropyl)pyromellitic dianhydride, pentafluoroethylpyromellitic dianhydride, bis{3,5-di(trifluoromethyl)phenoxy}pyromellitic dianhydride, 2,2-bis (3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 5,5'-bis(trifluoromethyl)-3,3',4,4'-tetracarboxybiphenyl dianhydride, 2,2', 5,5'-tetrakis(trifluoromethyl)-3,3',4,4'-tetracarboxybiphenyl dianhydride, 5,5'-bis(trifluoromethyl)-3,3',4,4' -Tetracarboxydiphenyl ether dianhydride, 5,5'-bis(trifluoromethyl)-3,3',4,4'-tetracarboxybenzophenone dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}benzene dianhydride anhydride, bis{(trifluoromethyl)dicarboxyphenoxy}(trifluoromethyl)benzene dianhydride, bis(dicarboxyphenoxy)(trifluoromethyl)benzene dianhydride, bis(dicarboxyphenoxy)bis(trifluoro methyl)benzene dianhydride, bis(dicarboxyphenoxy)tetrakis(trifluoromethyl)benzene dianhydride, 2,2-bis{4-(3,4-dicarboxyphenoxy)phenyl}hexafluoropropane dianhydride, Bis{(trifluoromethyl)dicarboxyphenoxy}biphenyl dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}bis(trifluoromethyl)biphenyl dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}diphenyl ether Dianhydride, bis(dicarboxyphenoxy)bis(trifluoromethyl)biphenyl dianhydride, difluoropyromellitic dianhydride, 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene dianhydride and 1,4-bis(3,4-dicarboxytrifluorophenoxy)octafluorobiphenyl dianhydride.

As the tetracarboxylic dianhydride, it is preferable to use an alicyclic tetracarboxylic dianhydride in consideration of the heat resistance, transparency, etc. of the resulting polyimide resin.
Note that acid chlorides, esters, and the like of tetracarboxylic acids having the same basic skeleton as these can also be used.

Tetracarboxylic dianhydride may be used in combination with dicarboxylic anhydride. When these carboxylic acid anhydrides are used in combination, the properties of the resulting imide ring-containing polymer such as polyimide resin may become even better. Examples of dicarboxylic anhydrides include maleic anhydride, succinic anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, chlorendic anhydride, and methyltetrahydrophthalic anhydride. Examples include phthalic anhydride, glutaric anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, and the like.

[Diamine compound]
As the diamine compound, a compound represented by the following formula (a3-1) can typically be used. One type of diamine compound may be used alone, or two or more types may be used in combination.
_H2NA2 - ^NH2 _... (a3-1)
(In formula (a3-1), A ² represents a divalent organic group.)

In formula (a3-1), A ² is a divalent organic group, and may have one or more substituents in addition to the two amino groups in formula (a3-1).
Suitable examples of the substituent include 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, and a fluorinated alkyl group having 1 to 6 carbon atoms. A fluorinated alkoxy group or hydroxyl group of 1 or more and 6 or less is preferred.
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 as A ² is preferably 2, more preferably 6, and the upper limit is preferably 50, more preferably 30.
Although A ² may be an aliphatic group, it is preferably an organic group containing one or more aromatic rings.

When A ² is an organic group containing one or more aromatic rings, the organic group may be the aromatic group 1 itself, and the two or more aromatic groups may be an aliphatic hydrocarbon group or a halogenated aliphatic group. It may be a group bonded via a bond containing a group hydrocarbon group or a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. Bonds containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms contained in ^A2 include -CONH-, -NH-, -N=N-, -CH=N-, -COO-, - Examples include O-, -CO-, -SO-, -SO ₂ -, -S-, and -S-S-, and -O-, -CO-, -SO-, -SO ₂ -, -S -, and -SS- are preferred.

The aromatic ring bonded to the amino group in A ² is preferably a benzene ring. When the ring bonded to the amino group in A ² 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.
Further, the aromatic ring contained in A ² 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－Ｃ（ＣＨ_３）_２－Ｃ_６Ｈ_４－Ｏ－、－Ｏ－Ｃ_６Ｈ_４－Ｃ（ＣＦ_３）_２－Ｃ_６Ｈ_４－Ｏ－、－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 A ² is an organic group containing an aromatic ring, from the viewpoint of heat resistance of the polyimide resin formed using the varnish composition, the organic group is a group represented by the following formulas (21) to (24). It is preferable that at least one of the above is used.

(In formulas (21) to (24), R ¹¹¹ is a group consisting of a hydrogen atom, a fluorine atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, and a halogenated alkyl group having 1 to 4 carbon atoms. In the formula (24), Q is a 9,9'-fluorenylidene group, or 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 -, -C(CH ₃ ) ₂ -, -CH ₂ -, -O-C ₆ H ₄ -C(CH ₃ ) ₂ -C ₆ H ₄ -O-, -O-C ₆ H ₄ -C(CF ₃ ) ₂ -C ₆ H ₄ -O-, -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-, - It represents one selected from the group consisting of groups represented by O-C ₆ H ₄ -C ₆ H ₄ -O- and -O-C ₆ H ₄ -O-.
In the example of Q, -C ₆ H ₄ - is a phenylene group, preferably m-phenylene group and p-phenylene group, more preferably p-phenylene group. In addition, -C ₁₀ H ₆ - is a naphthalene diyl group, and naphthalene-1,2-diyl group, naphthalene-1,4-diyl group, naphthalene-2,3-diyl group, naphthalene-2,6-diyl group and a naphthalene-2,7-diyl group are preferred, and a naphthalene-1,4-diyl group and a naphthalene-2,6-diyl group are more preferred. )

From the viewpoint of heat resistance of the polyimide resin 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, A hydrogen atom, a hydroxyl group, or a trifluoromethyl group is particularly preferred.

Q in formula (24) is 9,9'-fluorenylidene group, -O-C ₆ H ₄ -O-, -C(CF ₃ ) ₂ -, from the viewpoint of heat resistance of the polyimide resin formed. -O-, -C(CH ₃ ) ₂ -, -CH ₂ -, or -O-C ₆ H ₄ -C(CH ₃ ) ₂ -C ₆ H ₄ -O-, -CONH- are preferred, and -O -C ₆ H ₄ -O-, -C(CF ₃ ) ₂ - or -O- is particularly preferred.

When using an aromatic diamine as the diamine compound represented by formula (a3-1), for example, the aromatic diamines shown below can be suitably used.
That is, aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl ) biphenyl, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,4' -diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, 3,3'-diaminobenzanilide, 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, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 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 and the like. Among these, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenyl ether, and 4,4'-diaminobenzanilide are preferred in terms of price, availability, etc.

Further, as A ² , a silicon atom-containing group which may have a chain aliphatic group and/or an aromatic ring can be employed. As such a silicon atom-containing group, the groups shown below 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。） Furthermore, 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 A ² .

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

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

The cycloalkylene group having 3 to 20 carbon atoms in R ¹¹² and R ¹¹³ in formula (Si-1) is preferably a cycloalkylene group having 3 to 10 carbon atoms from the viewpoint of heat resistance and residual stress. , cyclobutylene group, cyclopentylene group, cyclohexylene group, cycloheptylene group, etc.
The arylene group having 6 to 20 carbon atoms in R ¹¹² and R ¹¹³ in formula (Si-1) is preferably an aromatic group having 6 to 20 carbon atoms from the viewpoint of heat resistance and residual stress. Examples include phenylene group and naphthylene group.

The alkyl group having 1 to 20 carbon atoms in R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ in formula (Si-1) is an alkyl group having 1 to 20 carbon atoms, from the viewpoint of heat resistance and residual stress. Alkyl groups are preferred, and specific examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, and hexyl groups.
The cycloalkyl group having 3 to 20 carbon atoms in R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ in formula (Si-1) has 3 to 10 carbon atoms from the viewpoint of heat resistance and residual stress. A cycloalkyl group is preferred, and specific examples include a cyclopentyl group and a cyclohexyl group.
The aryl group having 6 to 20 carbon atoms in R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ in formula (Si-1) is an aryl group having 6 to 12 carbon atoms from the viewpoint of heat resistance and residual stress. Aryl groups are preferred, and specific examples include phenyl, tolyl, and naphthyl groups.
Examples of the group containing an amino group having 20 or less carbon atoms in R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ in formula (Si-1) include an amino group, a substituted amino group (for example, bis(trialkylsilyl) ) amino group), etc.
The group represented by -OR ¹¹⁸ in R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , and R ¹¹⁷ in formula (Si-1) includes a methoxy group, an ethoxy group, a propoxy group, an isopropyloxy group, a butoxy group, Examples include phenoxy group, tolyloxy group, naphthyloxy group, propenyloxy group (eg, allyloxy group), and cyclohexyloxy group.
Among them, 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 allowing a silicon-containing compound having amino groups at both ends to act on an acid anhydride. Specific examples of such silicon-containing compounds include both terminally amino-modified methylphenyl silicones (for example, X-22-1660B-3 (number average molecular weight approximately 4,400) and X-22-9409 (manufactured by Shin-Etsu Chemical Co., Ltd.)). (number average molecular weight approximately 1,300)), dimethyl silicone modified with amino at both ends (for example, Shin-Etsu Chemical Co., Ltd., X-22-161A (number average molecular weight approximately 1,600), X-22-161B (number average molecular weight 3, 000) and KF8012 (number average molecular weight of approximately 4,400); BY16-835U manufactured by Dow Corning Toray (number average molecular weight of approximately 900); and Silaplane FM3311 manufactured by JNC (number average molecular weight of approximately 1000). It will be done.

[Method for producing polyamic acid (A)]
The polyamic acid (A) having the structural unit represented by the formula (a1) typically comprises a tetracarboxylic dianhydride represented by the above formula (a1-1) and the above formula (a3- A polymer obtained by reacting a diamine compound represented by 1) in a solvent, and a polymer obtained by using one or more types of diamine compound and/or tetracarboxylic dianhydride, respectively. Good too. For example, it may be a polymer obtained by polycondensing a diamine compound and a mixture containing two or more types of tetracarboxylic dianhydrides. Moreover, the polyamic acid (A) can be used alone or in combination of two or more types.

The amount of the tetracarboxylic dianhydride and diamine compound to be used when synthesizing polyamic acid (A) is not particularly limited, but the amount of the diamine compound used is 0.50 mol or more per 1 mol of the tetracarboxylic dianhydride. It is preferable to use 0.50 mol or less, more preferably 0.60 mol or more and 1.30 mol or less, particularly preferably 0.70 mol or more and 1.20 mol or less.
Further, the weight average molecular weight of the obtained polyamic acid (A) may be appropriately set according to its use, but 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 obtained polyamic acid (A) is, for example, 100,000 or less, preferably 80,000 or less, and more preferably 75,000 or less.
This weight average molecular weight may be set to the above-mentioned value by adjusting the blending amounts of the tetracarboxylic dianhydride and diamine compound, and reaction conditions such as the solvent and reaction temperature.

The reaction between a tetracarboxylic dianhydride and a diamine compound is usually carried out in an organic solvent. The organic solvent used in the reaction between the tetracarboxylic dianhydride and the diamine compound is an organic solvent that can dissolve the tetracarboxylic dianhydride and the diamine compound and does not react with the tetracarboxylic dianhydride and the diamine compound. There are no particular limitations as long as it is a solvent. Organic solvents can be used alone or in combination of two or more.

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

Among these organic solvents, 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.

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

By the method explained above, a solution containing polyamic acid (A) can be obtained.
The solution containing the polyamic acid (A) obtained as described above can be used as it is for preparing a varnish composition, or the solution containing the polyamic acid (A) can be used as it is to prepare a varnish composition. A paste or solid of polyamic acid obtained by removing at least a portion of the solvent from a solution of acid (A) can also be used for preparing the varnish composition.

The content of the polyamic acid (A) in the varnish composition is appropriately determined by taking into consideration the coatability of the varnish composition, the solubility of the polyamic acid (A) in the solvent (S), and the like. Typically, the content of polyamic acid (A) in the varnish composition is preferably 5% by mass or more and 45% by mass or less, more preferably 7% by mass or more and 40% by mass or less, based on the mass of the varnish composition. , more preferably 10% by mass or more and 30% by mass or less.

<Amide compound (C)>
The amide compound (C) has the following formula (C1):
R ^c1 -(-CO-NH-R ^c2 ) _n ...(C1)
(In formula (C1), R ^c1 is an n-valent organic group bonded to a carbonyl group via a carbon-carbon bond, and R ^c2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. (n is an integer between 1 and 4.)
This is a compound represented by

When the varnish composition contains the amide compound (C), the varnish composition can be used to form a polyimide resin with improved physical properties such as thermal expansion coefficient, elongation at break, and tensile strength.
Furthermore, when the varnish composition contains the amide compound (C), it is easy to suppress the occurrence of clouding or gelation over time when the varnish composition is stored. For this reason, the amide compound (C) is particularly preferably blended into a varnish composition containing a polyamic acid (A) that provides a transparent polyimide resin.

In formula (C1), n is an integer of 1 or more and 4 or less, preferably an integer of 1 or more and 3 or less, more preferably 1 or 2, and even more preferably 1. In view of the excellent effect of reducing the thermal expansion coefficient and the effect of increasing the tensile strength of the polyimide resin formed using the varnish composition, n is preferably 3 or 4. From the viewpoint of good dissolution stability of the amide compound (C) in the varnish composition, n is preferably 1 or 2, and more preferably 1.

In formula (C1), the number of carbon atoms in R ^c1 is not particularly limited as long as it does not impede the object of the present invention. The number of carbon atoms in R ^c1 is typically preferably 1 or more and 20 or less, more preferably 1 or more and 16 or less, and even more preferably 1 or more and 10 or less.

The organic group as R ^c1 may contain one or more types of heteroatoms. Examples of heteroatoms include nitrogen atoms, oxygen atoms, sulfur atoms, selenium atoms, boron atoms, phosphorus atoms, and halogen atoms. Examples of the halogen atom include a chlorine atom, a bromine atom, a fluorine atom, and an iodine atom.

When R ^c1 is a monovalent group, preferred specific examples of R ^c1 include saturated aliphatic groups such as an alkyl group, a cycloalkyl group, and a polycycloalkyl group, an alkenyl group, a cycloalkenyl group, and a polycycloalkyl group. Unsaturated aliphatic groups such as alkenyl groups, aryl groups (aromatic hydrocarbon groups), heteroaryl groups (aromatic heterocyclic groups), arylalkyl groups, arylalkenyl groups, heteroarylalkyl groups, heteroarylalkenyl groups, etc. can be mentioned.
Note that R ^c1 is not limited to a monovalent group, but R ^c1 is an aryl group or a heteroaryl group in that it is easy to suppress rapid decomposition, sublimation, volatilization, etc. of the amide compound (C) during polyimide resin production. It is preferable that it contains a group, and more preferably it contains an aryl group.

The alkyl group and alkenyl group as R ^c1 are a group consisting of a halogen atom, a cyano group, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an aliphatic acyl group having 2 to 6 carbon atoms, and an amino group. It may be substituted with one or more substituents selected from the following.
The cycloalkyl group, polycycloalkyl group, cycloalkenyl group, polycycloalkenyl group, aryl group, and heteroaryl group as R ^c1 are halogen atoms, cyano groups, hydroxyl groups, and alkyl groups having 1 to 6 carbon atoms. , an alkoxy group having 1 to 6 carbon atoms, an aliphatic acyl group having 2 to 6 carbon atoms, and an amino group.
In the arylalkyl group, arylalkenyl group, heteroarylalkyl group, and heteroarylalkenyl group as R ^c1 , the aryl group or heteroaryl group contained in these groups is a halogen atom, a cyano group, a hydroxyl group, or a carbon atom number of 1. Substituted with one or more substituents selected from the group consisting of an alkyl group having 6 or less carbon atoms, an alkoxy group having 1 or more carbon atoms and 6 or less carbon atoms, an aliphatic acyl group having 2 or more carbon atoms and 6 or less carbon atoms, and an amino group. You can.
In addition, not only when R ^c1 is a monovalent group but also when the polyimide resin is transparent, it is preferable that R ^c1 has an amino group and a hydroxyl group in order to easily form a highly transparent polyimide resin. Preferably not.

Preferred specific examples when R ^c1 is a saturated aliphatic group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group , n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, and n-icosyl group; alkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group , cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cycloalkyl group such as cyclodecyl group; polycycloalkyl group such as adamantyl group, norbornyl group, isobornyl group, tricyclodecanyl group, and tetracyclododecanyl group Examples include groups.

Preferred specific examples when R ^c1 is an unsaturated aliphatic group include vinyl group, 1-methylvinyl group, 1-propenyl group, 2-propenyl group (allyl group), 3-butenyl group. , 4-pentenyl group, 5-hexenyl group, 6-heptenyl group, 7-octenyl group, 8-nonenyl group, and alkenyl groups such as 9-decenyl group; cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group , cycloalkenyl groups such as cycloheptenyl group, cyclooctenyl group, cyclononenyl group, and cyclodecenyl group; polycycloalkenyl groups such as adamantenyl group, norbornenyl group, isobornenyl group, tricyclodecenyl group, and tetracyclododecenyl group can be mentioned.

Preferred specific examples when R ^c1 is an aryl group (aromatic hydrocarbon group) include a phenyl group, a naphthalen-1-yl group, a naphthalen-2-yl group, and a 1,1'-biphenyl-4-yl group. 1,1'-biphenyl-3-yl group, and 1,1'-biphenyl-2-yl group.

Preferred specific examples when R ^c1 is a heteroaryl group (aromatic heterocyclic group) include a pyridyl group, a furyl group, a thienyl group, an imidazolyl group, a pyrazolyl group, an oxazolyl group, a thiazolyl group, an isoxazolyl group, and an isothiazolyl group. , benzoxazolyl group, benzothiazolyl group, and benzimidazolyl group.

Preferred specific examples when R ^c1 is an arylalkyl group include a benzyl group, a phenethyl group, a naphthalen-1-ylmethyl group, a naphthalen-2-ylmethyl group, a naphthalen-1-ylethyl group, and a naphthalen-2-ylmethyl group. Examples include groups.

Preferred specific examples when R ^c1 is an arylalkenyl group include 2-phenylvinyl group, 2-(naphthalen-1-yl)vinyl group, and 2-(naphthalen-2-yl)vinyl group. It will be done.

Preferred specific examples when R ^c1 is a heteroarylalkyl group include a 1H-imidazol-2-ylmethyl group, a 1H-imidazol-2-ylethyl group, a pyridin-2-ylmethyl group, a pyridin-3-ylmethyl group, Examples include pyridin-4-ylmethyl group, pyridin-2-ylethyl group, pyridin-3-ylethyl group, and pyridin-4-ylethyl group.

Preferred specific examples when R ^c1 is a heteroarylalkenyl group include 2-(1H-imidazol-2-yl)2-(pyridin-2-yl)vinyl group, 2-(pyridin-3-yl) Examples include vinyl group, 2-(pyridin-4-yl)vinyl group, and the like.

When R ^c1 is a divalent group, preferred specific examples of R ^c1 include divalent saturated aliphatic groups such as alkanediyl groups, cycloalkanediyl groups, and polycycloalkanediyl groups having 2 or more carbon atoms. One hydrogen atom each from an alkyl group and an aryl group in a divalent unsaturated aliphatic group such as a group, an alkenediyl group, a cycloalkenediyl group, and a polycycloalkenediyl group, an arylene group, a heteroarylene group, and an alkylarene. removed group, a group obtained by removing one hydrogen atom each from an alkenyl group and an aryl group in an alkenyl arene, a group obtained by removing one hydrogen atom each from an alkyl group and a heteroaryl group in an alkylheteroarene, a group obtained by removing one hydrogen atom from each of an alkyl group and a heteroaryl group in an alkenylheteroarene. A group obtained by removing one hydrogen atom from each of an alkenyl group and a heteroaryl group, a group obtained by removing one hydrogen atom from each of two alkyl groups in a dialkylarene, and one each from two alkyl groups in a dialkylheteroarene. Examples include groups in which each hydrogen atom is removed.

When R ^c1 is a trivalent group, preferred specific examples of R ^c1 include an alkanetriyl group, a group represented by N-(-R ^c3 -) ₃ , an arenetriyl group, and a heteroarenetriyl group. An example is an yl group. R ^c3 is an alkylene group having 1 or more and 4 or less carbon atoms. R ^c3 is preferably an ethane-1,2-zyl group or a propane-1,3-diyl group.

When R ^c1 is a tetravalent group, preferred specific examples of R ^c1 include an alkantetrayl group, (-R ^c4 -) ₂ -N-(-R ^c5 -) -N-(-R ^c4 - ) A group represented by ₂ , an arenetetrayl group, and a heteroarenetetrayl group. R ^c4 and R ^c5 each independently represent an alkylene group having 1 or more and 4 or less carbon atoms. As R ^c4 and R ^c5 , ethane-1,2-zyl group and propane-1,3-diyl group are preferable.

In formula (C1), R ^c2 is a hydrogen atom or an alkyl group having 1 or more and 6 or less carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms as R ^c2 include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group. group, n-pentyl group, and n-hexyl group. Among these alkyl groups, methyl group and ethyl group are preferred, and ethyl group is more preferred.

Suitable examples of the amide compound (C) when R ^c1 is a monovalent saturated aliphatic hydrocarbon group include acetic acid amide (acetamide), propionic acid amide, butyric acid amide (butyric acid amide), isobutyric acid amide, Pentanoic acid amide (n-valeric acid amide), isovaleric acid amide, pivalic acid amide, hydroangelic acid amide, n-hexanoic acid amide, 2-methylpentanoic acid amide, 3-methylpentanoic acid, 4-methylpentanoic acid amide , 2,2-dimethylbutanoic acid amide, n-heptanoic acid amide, n-octanoic acid amide, n-nonanoic acid amide, n-decanoic acid amide, n-dodecanoic acid amide, n-tridecanoic acid amide, n-tetradecanoic acid amide, n-pentadecanoic acid amide, n-hexadecanoic acid amide, n-heptadecanoic acid amide, n-octadecanoic acid amide, n-nonadecanoic acid amide, n-icosanoic acid amide, cyclopropanecarboxylic acid amide, cyclopentanecarboxylic acid amide, Examples include cyclopropanecarboxylic acid amide, cycloheptanecarboxylic acid amide, and cyclooctanecarboxylic acid amide. Substituted compounds in which the nitrogen atom in the amide group of these compounds is substituted with a C1-C6 alkyl group are also preferable as the amide compound (C), and substituted compounds in which the nitrogen atom in the amide group of these compounds are substituted with a methyl group are also preferable as the amide compound (C). is more preferable as the amide compound (C).

Suitable examples of the amide compound (C) when R ^c1 is an alkyl group substituted with a halogen atom, a cyano group, a hydroxyl group, an acetyl group, or a methoxy group include chloroacetic acid amide, dichloroacetic acid amide, trichloroacetic acid Amide, bromoacetamide, dibromoacetamide, tribromoacetamide, fluoroacetamide, difluoroacetamide, trifluoroacetamide, cyanoacetamide, acetoacetamide, 3-chloropropionic acid amide, 3-bromopropionic acid amide, 3 - Fluoropropionic acid amide, 3-methoxypropionic acid amide, pentafluoropropionic acid amide, heptafluorobutyric acid amide, and lactic acid amide. Substituted compounds in which the nitrogen atom in the amide group of these compounds is substituted with a C1-C6 alkyl group are also preferable as the amide compound (C), and substituted compounds in which the nitrogen atom in the amide group of these compounds are substituted with a methyl group are also preferable as the amide compound (C). is more preferable as the amide compound (C).

Suitable examples of the amide compound (C) when R ^c1 is a monovalent unsaturated aliphatic hydrocarbon group include unsaturated aliphatic carboxylic acids such as acrylamide, methacrylamide, crotonamide, and oleamide. . Substituted compounds in which the nitrogen atom in the amide group of these compounds is substituted with a C1-C6 alkyl group are also preferable as the amide compound (C), and substituted compounds in which the nitrogen atom in the amide group of these compounds are substituted with a methyl group are also preferable as the amide compound (C). is more preferable as the amide compound (C).

Suitable examples of the amide compound (C) when R ^c1 is an aryl group include benzoic acid amide, 4-methylbenzoic acid amide, 3-methylbenzoic acid amide, 2-methylbenzoic acid amide, and 4-methoxybenzoic acid amide. Acid amide, 3-methoxybenzoic acid amide, 2-methoxybenzoic acid amide, 4-chlorobenzoic acid amide, 3-chlorobenzoic acid amide, 2-chlorobenzoic acid amide, 4-bromobenzoic acid amide, 3-bromobenzoic acid amide, 2-bromobenzoic acid amide, 4-fluorobenzoic acid amide, 3-fluorobenzoic acid amide, 2-fluorobenzoic acid amide, 4-hydroxybenzoic acid amide, 3-hydroxybenzoic acid amide, 2-hydroxybenzoic acid amide , 4-aminobenzoic acid amide, 3-aminobenzoic acid amide, 2-aminobenzoic acid amide, naphthalene-2-carboxylic acid amide, naphthalene-1-carboxylic acid amide, and 1,1'-biphenyl-4-carboxylic acid Among them are amides. Substituted compounds in which the nitrogen atom in the amide group of these compounds is substituted with a C1-C6 alkyl group are also preferable as the amide compound (C), and substituted compounds in which the nitrogen atom in the amide group of these compounds are substituted with a methyl group are also preferable as the amide compound (C). is more preferable as the amide compound (C).

Suitable examples of the amide compound (C) when R ^c1 is an arylalkyl group include phenylacetamide, 4-methylphenylacetamide, 3-methylphenylacetamide, 2-methylphenylacetamide, 2,5 -dimethylphenylacetamide, 2,4,6-trimethylphenylacetamide, 4-tert-butylphenylacetamide, 4-hydroxyphenylacetamide, 3-hydroxyphenylacetamide, 2-hydroxyphenylacetamide, 4-methoxy Phenylacetic acid amide, 3-methoxyphenylacetic acid amide, 2-methoxyphenylacetic acid amide, 4-chlorophenylacetic acid amide, 3-chlorophenylacetic acid amide, 2-chlorophenylacetic acid amide, 4-bromophenylacetic acid amide, 3-bromophenylacetic acid amide, 2-Bromophenylacetamide, 4-fluorophenylacetamide, 3-fluorophenylacetamide, 2-fluorophenylacetamide, 4-trifluoromethylphenylacetamide, 3-trifluoromethylphenylacetamide, 4-hydroxymethyl Phenylacetamide, 3-methoxyphenylacetamide, 4-aminophenylacetamide, 2-phenylpropionic acid amide, 2-phenyl-n-butyric acid amide, 2-phenylisobutyric acid amide, naphthalen-1-yl acetate amide, naphthalene- Examples include 2-ylacetamide and 1,1'-biphenyl-4-ylacetamide. Substituted compounds in which the nitrogen atom in the amide group of these compounds is substituted with a C1-C6 alkyl group are also preferable as the amide compound (C), and substituted compounds in which the nitrogen atom in the amide group of these compounds are substituted with a methyl group are also preferable as the amide compound (C). is more preferable as the amide compound (C).

Suitable examples of the amide compound (C) when R ^c1 is an arylalkenyl group include cinnamic acid amide, 4-methyl cinnamic acid amide, 3-methyl cinnamic acid amide, 2-methyl cinnamic acid amide, 2,5 -dimethyl cinnamic acid amide, 2,4,6-trimethyl cinnamic acid amide, 4-tert-butyl cinnamic acid amide, 4-hydroxy cinnamic acid amide, 3-hydroxy cinnamic acid amide, 2-hydroxy cinnamic acid amide, 4-methoxy Cinnamic acid amide, 3-methoxycinnamic acid amide, 2-methoxyphenylacetic acid amide, 4-chlorocinnamic acid amide, 3-chlorophenylacetic acid amide, 2-chlorocinnamic acid amide, 4-bromophenylacetic acid amide, 3-bromocinnamic acid amide, 2-bromocinnamic acid amide, 4-fluorocinnamic acid amide, 3-fluorocinnamic acid amide, 2-fluorocinnamic acid amide, 4-trifluoromethylcinnamic acid amide, 3-trifluoromethylcinnamic acid amide, 4- Included are hydroxymethyl cinnamic acid amide, 3-methoxycinnamic acid amide, and 4-aminocinnamic acid amide. Substituted compounds in which the nitrogen atom in the amide group of these compounds is substituted with a C1-C6 alkyl group are also preferable as the amide compound (C), and substituted compounds in which the nitrogen atom in the amide group of these compounds are substituted with a methyl group are also preferable as the amide compound (C). is more preferable as the amide compound (C).

Suitable examples of the amide compound (C) when R ^c1 is a divalent organic group include malonamide, succinamide (succinamide), adipoamide, sebacamide, dodecanedioic acid diamide, dichloromalonamide, dibromomalonamide, Terephthalic acid diamide, isophthalic acid diamide, phthalic acid diamide, naphthalene-2,6-dicarboxylic acid diamide, naphthalene-2,7-dicarboxylic acid diamide, naphthalene-1,4-dicarboxylic acid diamide, biphenyl-4,4'-dicarboxylic acid diamide acid diamide, 1,4-phenylenediacetic acid diamide, 1,3-phenylenediacetic acid diamide, and 1,2-phenylenediacetic acid diamide. Substituted compounds in which one or two of the nitrogen atoms in the amide group of these compounds are substituted with a C1-C6 alkyl group are also preferable as the amide compound (C); More preferred as the amide compound (C) is a substituent in which one or two of the methyl groups are substituted.

Suitable examples of the amide compound (C) when R ^c1 is a trivalent organic group include 1,2,3-propanetricarboxylic acid triamide, 1,2,3-propanetricarboxamide, 3,3', 3”-nitrilotris (propionamide), benzene-1,2,3-tricarboxylic triamide, benzene-1,2,4-tricarboxylic triamide, benzene-1,3,4-tricarboxylic triamide, and benzene-1 , 3,5-tricarboxylic acid triamide.Substituted products in which one to three nitrogen atoms in the amide group of these compounds are substituted with a C1-C6 alkyl group are also preferable as the amide compound (C), Substituted compounds in which one to three nitrogen atoms in the amide group of these compounds are substituted with methyl groups are more preferable as the amide compound (C).

Suitable examples of the amide compound (C) when R ^c1 is a tetravalent organic group include ethylenediaminetetraacetic acid tetraamide and naphthalene-1,4,5,8-tetracarboxylic acid tetraamide. Substituted compounds in which 1 to 4 of the nitrogen atoms in the amide group of these compounds are substituted with C1-C6 alkyl groups are also preferable as amide compounds (C); A substituent in which three to four methyl groups are substituted is more preferable as the amide compound (C).

Among the amide compounds (C) explained above, acetamide, N-methylacetamide, N-ethylacetamide, benzoic acid amide, N-methylbenzoic acid amide, N-ethylbenzoic acid amide, phenylacetamide, N-methylphenyl Acetamide, N-ethylphenylacetamide, cinnamic acid amide, N-methyl cinnamic acid amide, N-ethyl cinnamic acid amide, malonamide, N,N'-dimethylmalonamide, N,N'-diethylmalonamide, 3, 3',3''-nitrilotris (propionamide), 3,3',3''-nitrilotris (N-methylpropionamide), and 3,3',3''-nitrilotris (N-ethylpropionamide) preferable.

The amount of the amide compound (C) used in the varnish composition is not particularly limited as long as the object of the present invention is not impaired. The amount of the amide compound (C) to be used is determined according to the varnish composition because it is easy to obtain the desired improvement effect on the physical properties of the polyimide resin while preventing excessive sublimation and volatilization of the amide compound (C) during the production of the polyimide resin. It is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 3 parts by mass or more and 30 parts by mass or less, and even more preferably 5 parts by mass or more and 25 parts by mass or less, based on the total solid content of the product.
Further, when the varnish composition contains a thermal base generator (B), the mass ratio ((B):(C)) of the thermal base generator (B) and the amide compound (C) is, for example, 100:30. ~100:500, more preferably 100:100~100:300. The thermal base generator (B) is preferably a compound represented by the below-mentioned formula (B1), formula (B2), or formula (B4), more preferably a compound represented by formula (B4). .

<Solvent (S)>
The varnish composition contains a solvent (S). The varnish composition may be a paste containing solids or a solution, but is preferably a solution. The solvent (S) can be used alone or in combination of two or more.
The type of solvent (S) is not particularly limited as long as it does not impede the purpose of the present invention, and includes water, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl. Ethers, glycol monoethers such as propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, and diethylene glycol monophenyl ether; ethylene glycol dimethyl ether, ethylene glycol Glycol diethers such as diethyl ether, ethylene glycol dipropyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol dipropyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol Glycol monoacetates such as monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, and diethylene glycol monoethyl ether acetate; diethylene glycol monopropyl ether acetate, diethylene glycol mono Butyl ether acetate, diethylene glycol monophenyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate, 4-methoxybutyl acetate, 2-methyl -3-Methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl acetate, 2-ethoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate, 2-methoxypentyl acetate , 3-methoxypentyl acetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate, and 4-methyl-4- Monoether monoacetate of diols such as methoxypentyl acetate; Ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl shisobutyl ketone, ethyl isobutyl ketone, and cyclohexanone; methyl propionate, ethyl propionate, propyl propionate, propionic acid Isopropyl, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, 2-hydroxy-2-methyl, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate , ethyl-3-propoxypropionate, propyl-3-methoxypropionate, isopropyl-3-methoxypropionate, ethyl ethoxyacetate, ethyl oxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl acetate, acetic acid Ethyl, propyl acetate, isopropyl acetate, butyl acetate, isoamyl acetate, methyl carbonate, ethyl carbonate, propyl carbonate, butyl carbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butyl pyruvate, methyl acetoacetate, ethyl acetoacetate, Esters such as benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, and γ-butyrolactone; ethers such as diethyl ether, dipropyl ether, dibutyl ether, dihexyl ether, benzyl methyl ether, benzyl ethyl ether, and tetrahydrofuran. Aromatics such as benzene, toluene, xylene, ethylbenzene, cresol, and chlorobenzene; Aliphatic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, n-hexanol, and cyclohexanol; polyethylene glycol , glycols such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; glycerin; and the like.
Moreover, the solvent used in the reaction of the above-mentioned tetracarboxylic dianhydride and diamine compound can also be suitably used as the solvent (S).

（式（Ｓ１）中、Ｒ^Ｓ１及びＲ^Ｓ２は、それぞれ独立に炭素原子数１以上３以下のアルキル基であり、Ｒ^Ｓ３は、水素原子、又は下記式（Ｓ１－１）若しくは下記式（Ｓ１－２）：

で表される基であり、Ｒ^Ｓ４は、水素原子又は水酸基であり、Ｒ^Ｓ５及びＲ^Ｓ６は、それぞれ独立に、水素原子、炭素原子数１以上３以下のアルキル基であり、Ｒ^Ｓ７及びＲ^Ｓ８は、それぞれ独立に水素原子、又は炭素原子数１以上３以下のアルキル基であり、Ｒ^Ｓ３が式（Ｓ１－１）で表される基である場合、Ｒ^Ｓ２及びＲ^Ｓ３は、互いに結合して環を形成してもよい。） The solvent (S) may contain a nitrogen-containing compound represented by the following formula (S1).

(In formula (S1), R ^S1 and R ^S2 are each independently an alkyl group having 1 to 3 carbon atoms, and R ^S3 is a hydrogen atom, or the following formula (S1-1) or the following formula (S1 -2):

R ^S4 is a hydrogen atom or a hydroxyl group, R ^S5 and R ^S6 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ^S7 and R ^S8 is each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and when R ^S3 is a group represented by formula (S1-1), R ^S2 and R ^S3 are bonded to each other. may be used to form a ring. )

Among the nitrogen-containing compounds represented by formula (S1), specific examples when R ^S3 is a hydrogen atom or a group represented by formula (S1-1) include N,N-dimethylformamide, N , N-dimethylacetamide, N,N,2-trimethylpropionamide, N-ethyl,N,2-dimethylpropionamide, N,N-diethyl-2-methylpropionamide, N,N,2-trimethyl-2- Examples include hydroxypropionamide, N-ethyl-N,2-dimethyl-2-hydroxypropionamide, and N,N-diethyl-2-hydroxy-2-methylpropionamide.

In the nitrogen-containing compound represented by formula (S1), when R ^S3 is a group represented by formula (S1-1) and R ^S2 and R ^S3 are bonded to each other to form a ring, Specific examples include N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone.

Among the nitrogen-containing compounds represented by formula (S1), specific examples when R ^S3 is a group represented by formula (S1-2) include N,N,N',N'-tetramethylurea. , N,N,N',N'-tetraethylurea and the like.

Among the above examples of nitrogen-containing compounds represented by formula (S1), particularly preferred compounds include N,N-dimethylformamide, N,N-dimethylacetamide, N,N,2-trimethylpropionamide, and N , N,N',N'-tetramethylurea. Among these, N,N,2-trimethylpropionamide and N,N,N',N'-tetramethylurea are preferred. The boiling point of N,N,2-trimethylpropionamide under atmospheric pressure is 175°C, and the boiling point of N,N,N',N'-tetramethylurea is 177°C under atmospheric pressure. Thus, N,N,2-trimethylpropionamide and N,N,N',N'-tetramethylurea have relatively low boiling points among organic solvents (SI).
Therefore, when using a varnish composition containing a solvent (S) containing at least one selected from N,N,2-trimethylpropionamide and N,N,N',N'-tetramethylurea, When forming a polyimide resin, the solvent (S) is unlikely to remain in the polyimide resin produced by heating, and the mechanical properties of the resulting polyimide resin are unlikely to deteriorate.

Furthermore, N,N,2-trimethylpropionamide and N,N,N',N'-tetramethylurea are classified as SVHC (substances of concern for toxicity) under the REACH regulation in the European Union (EU). It is also useful because it is a substance with low toxicity, as it is not designated as a substance of very high concern.

The content of the solvent (S) in the varnish composition is not particularly limited as long as it does not impede the object of the present invention. The content of the solvent (S) in the varnish composition is appropriately adjusted depending on the solid content in the varnish composition. The solid content in the varnish composition is, for example, in the range of 5% by mass or more and 99.9% by mass or less, preferably 5% by mass or more and 70% by mass or less, and more preferably 10% by mass or more and 60% by mass or less.

<Thermal base generator (B)>
In order to facilitate the production of polyamide resin from polyamic acid (A) by firing, the varnish composition preferably contains a thermal base generator (B) that generates a basic nitrogen-containing heterocyclic compound by heating.

The basic nitrogen-containing heterocyclic compound generated by the thermal base generator (B) may be an aliphatic cyclic compound or an aromatic compound. When the basic nitrogen-containing heterocyclic compound is a compound in which two or more monocycles are condensed, the two or more monocycles may consist of only an aliphatic ring, or only an aromatic ring. It may consist of a combination of a group ring and an aromatic ring.

Examples of the basic nitrogen-containing heterocyclic compound generated by the thermal base generator (B) include pyrrolidine, pyrazolidine, imidazolidine, triazolidine, tetrazolidine, pyrroline, pyrazoline, imidazoline, triazoline, tetrazoline, pyrrole, pyrazole, imidazole, and triazole. Nitrogen-containing 5-membered ring compounds such as Examples include compounds condensed with cyclopentane, cyclohexane, benzene, etc.
When the basic nitrogen-containing heterocyclic compound has a substituent on the nitrogen-containing heterocycle, the substituent includes the same groups as R ¹ , R ² , and R ³ in formula (B1) described below. Can be mentioned.

（式（Ｂ１）中、Ｒ^１、Ｒ^２、及びＲ^３は、それぞれ独立に水素原子、ハロゲン原子、水酸基、シリル基、シラノール基、ニトロ基、ニトロソ基、スルホナト基、ホスフィノ基、ホスフィニル基、ホスホナト基、又は有機基である。）
で表されるイミダゾール化合物が好ましい。 The basic nitrogen-containing heterocyclic compound generated by the thermal base generator (B) component has the following formula (B1):

(In formula (B1), R ¹ , R ² , and R ³ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfonato group, a phosphino group, a phosphinyl group, (phosphonato group or organic group)
An imidazole compound represented by is preferred.

Examples of the organic group for R ¹ , R ² , and R ³ include an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group, an aralkyl group, and the like. This organic group may contain a bond or substituent other than a hydrocarbon group such as a hetero atom. Further, this organic group may be linear, branched, or cyclic. This organic group is usually monovalent, but when forming a cyclic structure, it can be a divalent or higher organic group.

R ¹ and R ² may be bonded together to form a cyclic structure, and may further include a heteroatom bond. Examples of the cyclic structure include a heterocycloalkyl group and a heteroaryl group, and may be a fused ring.

The bonds contained in the organic groups of R ¹ , R ² and R ³ are not particularly limited as long as the effects of the present invention are not impaired. The organic group may include a bond containing a heteroatom such as an oxygen atom, a nitrogen atom, or a silicon atom. Specific examples of bonds containing heteroatoms include ether bonds, carbonyl bonds, thiocarbonyl bonds, ester bonds, amide bonds, urethane bonds, and imino bonds (-N=C(-R)-, -C(=NR)- :R represents a hydrogen atom or an organic group), a carbonate bond, a sulfonyl bond, an azo bond, etc.

From the viewpoint of heat resistance of the imidazole compound, examples of the bond containing a heteroatom that the organic groups of R ¹ , R ² , and R ³ may include include an ether bond, a carbonyl bond, a thiocarbonyl bond, an ester bond, and an amide bond. , urethane bond, imino bond (-N=C(-R)-, -C(=NR)-: R represents a hydrogen atom or a monovalent organic group), carbonate bond, and sulfonyl bond.

When the organic group of R ¹ , R ² , and R ³ is a substituent other than a hydrocarbon group, R ¹ , R ² , and R ³ are not particularly limited as long as the effects of the present invention are not impaired. As mentioned above, specific examples of R ¹ , R ² and R ³ are a halogen atom, a hydroxyl group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfonato group, a phosphino group, a phosphinyl group, and a phosphonato group. The hydrogen atom included in the above substituent may be substituted with a hydrocarbon group. Moreover, the hydrocarbon group contained in the above-mentioned substituent may be linear, branched, or cyclic.

R ¹ , R ² , and R ³ include a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and a halogen. An atom is preferable, and a hydrogen atom is more preferable.

The thermal base generator (B) is not particularly limited as long as it is a compound that can generate a basic nitrogen-containing heterocyclic compound by heating. Regarding compounds that generate amines under the action of heat (thermal base generators), which have been conventionally blended into various compositions, it is possible to convert the skeleton derived from the amines generated during heating into the desired basic nitrogen-containing heterocyclic compound. By substituting the derived skeleton, a compound used as a thermal base generator (B) can be obtained.

（式（Ｂ２）中、Ｒ^１、Ｒ^２、及びＲ^３は、式（Ｂ１）におけるこれらと同様であり、Ｒ^ｂ１及びＲ^ｂ２は、それぞれ独立に水素原子、ハロゲン原子、水酸基、シリル基、シラノール基、ニトロ基、ニトロソ基、スルフィノ基、スルホ基、スルホナト基、ホスフィノ基、ホスフィニル基、ホスホノ基、ホスホナト基、又は有機基を示し、Ｒ^ｂ３、Ｒ^ｂ４、Ｒ^ｂ５、Ｒ^ｂ６、及びＲ^ｂ７は、それぞれ独立に水素原子、ハロゲン原子、水酸基、シリル基、シラノール基、ニトロ基、ニトロソ基、スルフィノ基、スルホ基、スルホナト基、ホスフィノ基、ホスフィニル基、ホスホノ基、ホスホナト基、アミノ基、アンモニオ基、又は有機基を示し、Ｒ^ｂ３、Ｒ^ｂ４、Ｒ^ｂ５、Ｒ^ｂ６、及びＲ^ｂ７は、それらの２つ以上が結合して環状構造を形成していてもよく、ヘテロ原子の結合を含んでいてもよい。）
で表される化合物が挙げられる。 A suitable thermal base generator (B) has the following formula (B2):

(In formula (B2), R ¹ , R ² , and R ³ are the same as those in formula (B1), and R ^b1 and R ^b2 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a silyl group, Represents a silanol group, nitro group, nitroso group, sulfino group, sulfo group, sulfonato group, phosphino group, phosphinyl group, phosphono group, phosphonato group, or organic group, R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, It represents an ammonio group or an organic group, and two or more of R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 may combine to form a cyclic structure, and a heteroatom bond may be formed. may be included.)
Examples include compounds represented by:

In formula (B2), R ¹ , R ² , and R ³ are the same as those described for formula (B1).

In formula (B2), R ^b1 and R ^b2 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group. , represents a phosphono group, a phosphonato group, or an organic group.

Examples of the organic group for R ^b1 and R ^b2 include the groups exemplified for R ¹ , R ² , and R ³ . This organic group may contain a heteroatom therein, as in the case of R ¹ , R ² , and R ³ . Further, this organic group may be linear, branched, or cyclic.

Among the above, R ^b1 and R ^b2 each independently include a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 4 to 13 carbon atoms, and a cycloalkyl group having 4 to 13 carbon atoms. Alkenyl group, aryloxyalkyl group having 7 to 16 carbon atoms, aralkyl group having 7 to 20 carbon atoms, alkyl group having cyano group and having 2 to 11 carbon atoms, and having hydroxyl group and having 1 or more carbon atoms Alkyl group having 10 or less carbon atoms, alkoxy group having 1 to 10 carbon atoms, amide group having 2 to 11 carbon atoms, acyl group having 1 to 10 carbon atoms, ester group having 2 to 11 carbon atoms ( -COOR, -OCOR: R represents a hydrocarbon group), an aryl group having 6 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms substituted with an electron-donating group and/or an electron-withdrawing group , a benzyl group or a cyano group substituted with an electron-donating group and/or an electron-withdrawing group are preferable. More preferably, both R ^b1 and R ^b2 are hydrogen atoms, or R ^b1 is a methyl group and R ^b2 is a hydrogen atom.

In formula (B2), R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group. group, sulfino group, sulfo group, sulfonato group, phosphino group, phosphinyl group, phosphono group, phosphonato group, amino group, ammonio group, or organic group.

Examples of the organic groups for R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 include the groups exemplified for R ¹ , R ² , and R ³ . This organic group may contain a bond or substituent other than a hydrocarbon group, such as a hetero atom, in the organic group, as in the case of R ¹ , R ² , and R ³ . Further, this organic group may be linear, branched, or cyclic.

Two or more of R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 may be combined to form a cyclic structure. R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 may each contain a bond containing a hetero atom. Examples of the cyclic structure include a heterocycloalkyl group and a heteroaryl group, and may be a fused ring. For example, R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 are bonded together, and R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 are bonded to benzene. A condensed ring such as naphthalene, anthracene, phenanthrene, indene, etc. may be formed by sharing ring atoms. When a condensed ring is formed, the absorption wavelength becomes longer, which is preferable.

Among the above, R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 each independently include a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a cycloalkyl group having 4 to 13 carbon atoms. , a cycloalkenyl group having 4 to 13 carbon atoms, an aryloxyalkyl group having 7 to 16 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an alkyl group having 2 to 11 carbon atoms and having a cyano group. group, an alkyl group having 1 to 10 carbon atoms and having a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, an amide group having 2 to 11 carbon atoms, an acyl group having 1 to 10 carbon atoms, carbon Ester group having 2 to 11 atoms, aryl group having 6 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms substituted with an electron donating group and/or electron withdrawing group, electron donating group And/or the electron-withdrawing group is preferably a substituted benzyl group, cyano group, or nitro group.

（式（Ｂ３）中、Ｒ^１、Ｒ^２、及びＲ^３は、式（Ｂ１）及び（Ｂ２）と同義である。Ｒ^ｂ１～Ｒ^ｂ６は式（Ｂ２）と同義である。Ｒ^ｂ８は、水素原子又は有機基を示す。Ｒ^ｂ３及びＲ^ｂ４が水酸基となることはない。Ｒ^ｂ３、Ｒ^ｂ４、Ｒ^ｂ５、及びＲ^ｂ６は、それらの２つ以上が結合して環状構造を形成していてもよく、ヘテロ原子の結合を含んでいてもよい。）
で表される化合物が好ましい。 Among the compounds represented by the above formula (B2), the following formula (B3):

(In formula (B3), R ¹ , R ² , and R ³ have the same meanings as formulas (B1) and (B2). ^{R b1} to R ^b6 have the same meanings as formula (B2). ^{R b8} is Represents a hydrogen atom or an organic group. R ^b3 and R ^b4 never become a hydroxyl group. R ^b3 , R ^b4 , R ^b5 , and R ^b6 are two or more of them bonded together to form a cyclic structure. may contain a heteroatom bond.)
Compounds represented by are preferred.

Since the compound represented by formula (B3) has the substituent -O-R ^b8 , it has excellent solubility in the solvent (S).

In formula (B3), R ^b8 is a hydrogen atom or an organic group. When R ^b8 is an organic group, examples of the organic group include the groups exemplified for R ¹ , R ² , and R ³ . This organic group may contain a heteroatom within the organic group. Further, this organic group may be linear, branched, or cyclic. R ^b8 is preferably a hydrogen atom or an alkyl group having 1 or more and 12 or less carbon atoms, and more preferably a methyl group.

Specific examples of compounds particularly suitable as the thermal base generator (B) among the compounds represented by formula (B1) are shown below.

（式（Ｂ４）中、Ｒ^１、Ｒ^２、及びＲ^３は、式（Ｂ１）におけるこれらと同様であり、Ｒ^ｂ９は、水素原子又は１価の有機基を表し、Ｒ^ｂ１０は置換基を有してもよい芳香族基を表し、Ｒ^ｂ９は他方のＲ^ｂ９又はＲ^ｂ１０と結合して環状構造を形成してもよい。） Further, an imidazole compound represented by the following formula (B4) is also suitable as the thermal base generator (B).

(In formula (B4), R ¹ , R ² , and R ³ are the same as those in formula (B1), R ^b9 represents a hydrogen atom or a monovalent organic group, and R ^b10 represents a substituent. represents an optional aromatic group, and R ^b9 may combine with the other R ^b9 or R ^b10 to form a cyclic structure.)

In formula (B4), R ^b9 is a hydrogen atom or a monovalent organic group. The monovalent organic group is not particularly limited, and may be, for example, an alkyl group that may have a substituent, an aromatic group that may have a substituent, or the like. When R ^b9 is an alkyl group, the alkyl group may have an ester bond or the like in the chain.

The alkyl group may be the same as, for example, R ^b11 in formula (B4a) described below. The number of carbon atoms in the alkyl group is preferably 1 or more and 40 or less, more preferably 1 or more and 30 or less, particularly preferably 1 or more and 20 or less, and most preferably 1 or more and 10 or less.
The substituent that the alkyl group may have may be the same as the substituent that the alkylene group that is R ^b11 in formula (B4a) described below may have, for example.

The aromatic group which may have a substituent is the same as R ^b10 in formula (B4a) described below, preferably an aryl group, and more preferably a phenyl group. The aromatic group which may have a substituent as R ^b9 may be the same as or different from R ^b10 .
In formula (B4), one R ^b9 is preferably a hydrogen atom, one R ^b9 is a hydrogen atom, and the other R ^b9 has an alkyl group that may have a substituent or a substituent. More preferably, it is an aromatic group.
In formula (B4), R ^b9 may combine with the other R ^b9 or R ^b10 to form a cyclic structure. For example, when at least one R ^b9 is an alkyl group that may have a substituent, R ^b9 may be combined with the other R ^b9 or R ^b10 to form a cyclic structure.

The imidazole compound represented by the formula (B4) may be a compound represented by the following formula (B4a).

（式（Ｂ４ａ）中、Ｒ^１、Ｒ^２、及びＲ^３は式（Ｂ１）におけるこれらと同様であり、Ｒ^ｂ１１は水素原子又はアルキル基であり、Ｒ^ｂ１０は置換基を有してもよい芳香族基であり、Ｒ^ｂ１２は置換基を有してもよいアルキレン基であり、Ｒ^ｂ１２はＲ^ｂ１０と結合して環状構造を形成してもよい。）

(In formula (B4a), R ¹ , R ² , and R ³ are the same as those in formula (B1), R ^b11 is a hydrogen atom or an alkyl group, and R ^b10 may have a substituent. It is an aromatic group, R ^b12 is an alkylene group which may have a substituent, and R ^b12 may be combined with R ^b10 to form a cyclic structure.)

In formula (B4a), R ^b11 is a hydrogen atom or an alkyl group. When R ^b11 is an alkyl group, the alkyl group may be a straight chain alkyl group or a branched chain alkyl group. The number of carbon atoms in the alkyl group is not particularly limited, but is preferably 1 or more and 20 or less, preferably 1 or more and 10 or less, and more preferably 1 or more and 5 or less.

Specific examples of alkyl groups suitable as R ^b11 include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, Isopentyl group, tert-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethyl-n-hexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, and n-icosyl group.

In formula (B4a), R ^b10 is an aromatic group that may have a substituent. The aromatic group which may have a substituent may be an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.

The type of aromatic hydrocarbon group is not particularly limited as long as it does not impede the purpose of the present invention. The aromatic hydrocarbon group may be a monocyclic aromatic group, or may be a group formed by condensing two or more aromatic hydrocarbon groups, and may be a group formed by condensing two or more aromatic hydrocarbon groups. may be a group formed by bonding through a single bond. As the aromatic hydrocarbon group, phenyl group, naphthyl group, biphenylyl group, anthryl group, and phenanthrenyl group are preferable.

The type of aromatic heterocyclic group is not particularly limited as long as it does not impede the purpose of the present invention. The aromatic heterocyclic group may be a monocyclic group or a polycyclic group. Preferred examples of the aromatic heterocyclic group include a pyridyl group, a furyl group, a thienyl group, an imidazolyl group, a pyrazolyl group, an oxazolyl group, a thiazolyl group, an isoxazolyl group, an isothiazolyl group, a benzoxazolyl group, a benzothiazolyl group, and a benzimidazolyl group.

Examples of substituents that a phenyl group, a polycyclic aromatic hydrocarbon group, or an aromatic heterocyclic group may have include a halogen atom, a hydroxyl group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfino group, and a sulfo group. , a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, an ammonio group, and an organic group. When a phenyl group, a polycyclic aromatic hydrocarbon group, or an aromatic heterocyclic group has a plurality of substituents, the plurality of substituents may be the same or different.

When the substituent of the aromatic group is an organic group, examples of the organic group include an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group, an aralkyl group, and the like. This organic group may contain a bond or substituent other than a hydrocarbon group such as a hetero atom. Further, this organic group may be linear, branched, cyclic, or a combination of these structures. This organic group is usually monovalent, but when forming a cyclic structure, it can be a divalent or higher organic group.

When an aromatic group has substituents on adjacent carbon atoms, the two substituents bonded on adjacent carbon atoms may be bonded together to form a cyclic structure. Examples of the cyclic structure include aliphatic hydrocarbon rings and aliphatic rings containing heteroatoms.

When the substituent of the aromatic group is an organic group, the bonds contained in the organic group are not particularly limited as long as the effects of the present invention are not impaired, and the organic group may include oxygen atoms, nitrogen atoms, silicon atoms, etc. may contain a bond containing a heteroatom. Specific examples of bonds containing heteroatoms include ether bonds, carbonyl bonds, thiocarbonyl bonds, ester bonds, amide bonds, urethane bonds, and imino bonds (-N=C(-R)-, -C(=NR)- :R represents a hydrogen atom or an organic group), a carbonate bond, a sulfonyl bond, an azo bond, etc.

From the viewpoint of heat resistance of the imidazole compound represented by formula (B4) or formula (B4a), examples of the bond containing a heteroatom that the organic group may have include an ether bond, a carbonyl bond, a thiocarbonyl bond, and an ester bond. , amide bond, amino bond (-NR-: R represents a hydrogen atom or monovalent organic group) urethane bond, imino bond (-N=C(-R)-, -C(=NR)-: R is (representing a hydrogen atom or a monovalent organic group), a carbonate bond, and a sulfonyl bond are preferable.

When the organic group is a substituent other than a hydrocarbon group, the type of the substituent other than the hydrocarbon group is not particularly limited as long as it does not impede the object of the present invention. Specific examples of substituents other than hydrocarbon groups include halogen atoms, hydroxyl groups, mercapto groups, sulfide groups, cyano groups, isocyano groups, cyanato groups, isocyanato groups, thiocyanato groups, isothiocyanato groups, silyl groups, silanol groups, and alkoxy groups. , alkoxycarbonyl group, amino group, monoalkylamino group, dialkylaluminum group, monoarylamino group, diarylamino group, carbamoyl group, thiocarbamoyl group, nitro group, nitroso group, carboxylate group, acyl group, acyloxy group, sulfino group group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphonato group, an alkyl ether group, an alkenyl ether group, an aryl ether group, and the like. The hydrogen atom included in the above substituent may be substituted with a hydrocarbon group. Moreover, the hydrocarbon group contained in the above-mentioned substituent may be linear, branched, or cyclic.

The substituents of the phenyl group, polycyclic aromatic hydrocarbon group, or aromatic heterocyclic group include an alkyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, and 1 carbon atom. Preferred are an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, an arylamino group having 1 to 12 carbon atoms, and a halogen atom.

As R ^b10 , an imidazole compound represented by formula (B4) or formula (B4a) can be synthesized cheaply and easily, and imidazole compounds have good solubility in water and organic solvents, so R b10 has a substituent, respectively. A phenyl group, a furyl group, and a thienyl group are preferred.

In formula (B4a), R ^b12 is an alkylene group that may have a substituent. The substituent that the alkylene group may have is not particularly limited as long as it does not impede the object of the present invention. Specific examples of substituents that the alkylene group may have include a hydroxyl group, an alkoxy group, an amino group, a cyano group, and a halogen atom. The alkylene group may be a straight chain alkylene group or a branched chain alkylene group, and a straight chain alkylene group is preferred. The number of carbon atoms in the alkylene group is not particularly limited, and is preferably 1 or more and 20 or less, more preferably 1 or more and 10 or less, and particularly preferably 1 or more and 5 or less. Note that the number of carbon atoms in the alkylene group does not include carbon atoms in substituents bonded to the alkylene group.

The alkoxy group as a substituent bonded to the alkylene group may be a straight chain alkoxy group or a branched chain alkoxy group. The number of carbon atoms in the alkoxy group as a substituent is not particularly limited, and is preferably 1 or more and 10 or less, more preferably 1 or more and 6 or less, and particularly preferably 1 or more and 3 or less.

The amino group as a substituent bonded to the alkylene group may be a monoalkylamino group or a dialkylamino group. The alkyl group contained in the monoalkylamino group or dialkylamino group may be a straight-chain alkyl group or a branched-chain alkyl group. The number of carbon atoms in the alkyl group contained in the monoalkylamino group or dialkylamino group is not particularly limited, and is preferably 1 or more and 10 or less, more preferably 1 or more and 6 or less, and particularly preferably 1 or more and 3 or less.

Specific examples of alkylene groups suitable as R ^b12 include methylene group, ethane-1,2-diyl group, n-propane-1,3-diyl group, n-propane-2,2-diyl group, n-butane group. -1,4-diyl group, n-pentane-1,5-diyl group, n-hexane-1,6-diyl group, n-heptane-1,7-diyl group, n-octane-1,8-diyl group group, n-nonane-1,9-diyl group, n-decane-1,10-diyl group, n-undecane-1,11-diyl group, n-dodecane-1,12-diyl group, n-tridecane- 1,13-diyl group, n-tetradecane-1,14-diyl group, n-pentadecane-1,15-diyl group, n-hexadecane-1,16-diyl group, n-heptadecane-1,17-diyl group , n-octadecane-1,18-diyl group, n-nonadecane-1,19-diyl group, and n-icosane-1,20-diyl group.

Among the imidazole compounds represented by the above formula (B4), the compound represented by the following formula (B4-1a) is preferred because it can be synthesized inexpensively and easily.

（式（Ｂ４－１ａ）中、Ｒ^１、Ｒ^２、及び^Ｒ３は、式（Ｂ１）におけるこれらと同様であり、Ｒ^ｂ９は、式（Ｂ４）と同様であり、Ｒ^ｂ１３、Ｒ^ｂ１４、Ｒ^ｂ１５、Ｒ^ｂ１６、及びＲ^ｂ１７は、それぞれ独立に、水素原子、ハロゲン原子、水酸基、シリル基、シラノール基、ニトロ基、ニトロソ基、スルフィノ基、スルホ基、スルホナト基、ホスフィノ基、ホスフィニル基、ホスホノ基、ホスホナト基、アミノ基、アンモニオ基、又は有機基である。Ｒ^ｂ１３、Ｒ^ｂ１４、Ｒ^ｂ１５、Ｒ^ｂ１６、及びＲ^ｂ１７のうち少なくとも２つが結合して環状構造を形成してもよい。Ｒ^ｂ９はＲ^ｂ１５と結合して環状構造を形成してもよい。）
なお、式（Ｂ４－１ａ）において、Ｒ^ｂ１３、Ｒ^ｂ１４、Ｒ^ｂ１５、Ｒ^ｂ１６、及びＲ^ｂ１７は、全て水素原子であってもよい。また、式（Ｂ４－１）で表される化合物の溶媒（Ｓ）への溶解性の点で、Ｒ^ｂ１３、Ｒ^ｂ１４、Ｒ^ｂ１５、Ｒ^ｂ１６、及びＲ^ｂ１７のうちの少なくとも１つが水素原子以外の基であるのが好ましい。

(In formula (B4-1a), R ¹ , R ² , and ^R3 are the same as those in formula (B1), R ^b9 is the same as in formula (B4), and R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, and a phosphono group. group, phosphonato group, amino group, ammonio group, or organic group.At least two of ^{R b13} , R ^b14 , R ^b15 , R ^b16 , and R ^b17 may be bonded to form a cyclic structure. R ^b9 may combine with R ^b15 to form a cyclic structure.)
Note that in formula (B4-1a), R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 may all be hydrogen atoms. In addition, in terms of the solubility of the compound represented by formula (B4-1) in the solvent (S), at least one of R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 is other than a hydrogen atom. It is preferable that it is a group of

R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 are the same as those in formula (B4-1) described below. In formula (B4-1a), R ^b9 may combine with R ^b15 to form a cyclic structure. For example, when R ^b9 is an alkyl group that may have a substituent, R ^b9 may be combined with R ^b15 to form a cyclic structure.

Among the imidazole compounds represented by the above formula (B4a) or formula (B4-1a), the following formula (B4-1) is inexpensive and easily synthesized, and has excellent solubility in water and organic solvents. A compound represented by formula (B4-1) is preferred, and a compound represented by formula (B4-1) in which R ^b12 is a methylene group is more preferred.

（式（Ｂ４－１）中、Ｒ^１、Ｒ^２、及び^Ｒ３は式（Ｂ１）におけるこれらと同様であり、Ｒ^ｂ１１、及びＲ^ｂ１２は、式（Ｂ４ａ）におけるこれらと同様であり、Ｒ^ｂ１３、Ｒ^ｂ１４、Ｒ^ｂ１５、Ｒ^ｂ１６、及びＲ^ｂ１７は、それぞれ独立に、水素原子、ハロゲン原子、水酸基、シリル基、シラノール基、ニトロ基、ニトロソ基、スルフィノ基、スルホ基、スルホナト基、ホスフィノ基、ホスフィニル基、ホスホノ基、ホスホナト基、アミノ基、アンモニオ基、又は有機基である。Ｒ^ｂ１３、Ｒ^ｂ１４、Ｒ^ｂ１５、Ｒ^ｂ１６、及びＲ^ｂ１７のうち少なくとも２つが結合して環状構造を形成してもよい。Ｒ^ｂ１２はＲ^ｂ１５と結合して環状構造を形成してもよい。）
なお、式（Ｂ４－１）において、Ｒ^ｂ１３、Ｒ^ｂ１４、Ｒ^ｂ１５、Ｒ^ｂ１６、及びＲ^ｂ１７は、全て水素原子であってもよい。また、式（Ｂ４－１）で表される化合物の溶媒（Ｓ）への溶解性の点で、Ｒ^ｂ１３、Ｒ^ｂ１４、Ｒ^ｂ１５、Ｒ^ｂ１６、及びＲ^ｂ１７のうちの少なくとも１つが水素原子以外の基であるのが好ましい。

(In formula (B4-1), R ¹ , R ² , and ^R3 are the same as those in formula (B1), R ^b11 and R ^b12 are the same as these in formula (B4a), and R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfino group, a sulfo group, a sulfonato group, and a phosphino group. , a phosphinyl group, a phosphono group, a phosphonato group, an amino group, an ammonio group, or an organic group.At least two of R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 are bonded to form a cyclic structure. (R ^b12 may combine with R ^b15 to form a cyclic structure.)
Note that in formula (B4-1), R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 may all be hydrogen atoms. In addition, in terms of the solubility of the compound represented by formula (B4-1) in the solvent (S), at least one of R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 is other than a hydrogen atom. It is preferable that it is a group of

When R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 are organic groups, the organic group is the same as the organic group that R ^b10 in formula (B4a) has as a substituent. R ^b13 , R ^b14 , R ^b15 , and R ^b16 are preferably hydrogen atoms from the viewpoint of solubility of the imidazole compound in the solvent (S).

Among these, at least one of R ^b13 , R ^b14 , R ^b15 , R ^b16 , and R ^b17 is preferably the following substituent, and it is particularly preferable that R ^b17 is the following substituent. When R ^b17 is the following substituent, R ^b13 , R ^b14 , R ^b15 , and R ^b16 are preferably hydrogen atoms.
-OR ^b18
(R ^b18 is a hydrogen atom or an organic group.)

When R ^b18 is an organic group, the organic group is the same as the organic group that R ^b10 in formula (B4a) has as a substituent. R ^b18 is preferably an alkyl group, more preferably an alkyl group having 1 to 8 carbon atoms, particularly preferably an alkyl group having 1 to 3 carbon atoms, and most preferably a methyl group.

（式（Ｂ４－１－１）において、Ｒ^１、Ｒ^２、及び^Ｒ３は式（Ｂ１）におけるこれらと同様であり、Ｒ^ｂ１１は、式（Ｂ４ａ）と同様であり、Ｒ^ｂ１９、Ｒ^ｂ２０、Ｒ^ｂ２１、Ｒ^ｂ２２、及びＲ^ｂ２３は、それぞれ独立に、水素原子、水酸基、シリル基、シラノール基、ニトロ基、ニトロソ基、スルフィノ基、スルホ基、スルホナト基、ホスフィノ基、ホスフィニル基、ホスホノ基、ホスホナト基、アミノ基、アンモニオ基、又は有機基である。ただし、Ｒ^ｂ１９、Ｒ^ｂ２０、Ｒ^ｂ２１、Ｒ^ｂ２２、及びＲ^ｂ２３のうち少なくとも１つは水素原子以外の基である。） Among the compounds represented by the above formula (B4-1), the compounds represented by the following formula (B4-1-1) are preferred.

(In formula (B4-1-1), R ¹ , R ² , and ^R3 are the same as those in formula (B1), R ^b11 is the same as in formula (B4a), and R ^b19 , R ^b20 , R ^b21 , R ^b22 , and R ^b23 each independently represent a hydrogen atom, a hydroxyl group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, A phosphonato group, an amino group, an ammonio group, or an organic group.However, at least one of R ^b19 , R ^b20 , R ^b21 , R ^b22 , and R ^b23 is a group other than a hydrogen atom.)

Among the compounds represented by formula (B4-1-1), at least one of R ^b19 , R ^b20 , R ^b21 , R ^b22 , and R ^b23 is a group represented by the above-mentioned -O-R ^b18 . It is preferable that R ^b23 be a group represented by -O-R ^b18 . When R ^b23 is a group represented by -O-R ^b18 , R ^b19 , R ^b20 , R ^b21 and R ^b22 are preferably hydrogen atoms.

Preferred specific examples of the imidazole compound represented by formula (B4) or formula (B4a) include the following compounds.

The content of the thermal base generator (B) in the varnish composition is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, based on the mass of the varnish composition. By using the thermal base generator (B) in an amount within this range, the polyamide resin from the polyamic acid (A) can be produced without excessive volatilization or sublimation of the thermal decomposition products of the thermal base generator (B). production can be effectively promoted.

<Other ingredients>
The varnish composition may contain various additives as necessary. Examples of additives include colorants, dispersants, sensitizers, adhesion promoters, antioxidants, ultraviolet absorbers, anti-aggregation agents, antifoaming agents, surfactants, and the like. Further, the varnish composition may contain various fillers or reinforcing materials as necessary.
The amounts of various additives used are not particularly limited as long as they do not impede the purpose of the present invention. For example, it may be adjusted as appropriate within the range of 0.001% by mass or more and 60% by mass or less, preferably 0.05% by mass or more and 5% by mass or less, based on the mass of the solid content of the varnish composition.
The amount of filler or reinforcing material used is not particularly limited as long as it does not impede the purpose of the present invention. The amount of the filler or reinforcing material used is typically preferably 1% by mass or more and 300% by mass or less, more preferably 5% by mass or more and 200% by mass or less, and 10% by mass or less, more preferably 5% by mass or more and 200% by mass or less, based on the mass of the polyamic acid (A). More preferably, the content is from % by mass to 100% by mass.

As described above, by using the above varnish composition, it is possible to obtain a polyimide resin with improved physical properties such as thermal expansion coefficient, elongation at break, and tensile strength.

≪Production method of polyimide resin≫
A molding step of molding the varnish composition described above,
A polyimide resin can be manufactured by a method including an imidization step of heating and imidizing a molded varnish composition.

When molding the varnish composition, the shape of the molded varnish composition is not particularly limited. The method of molding the varnish composition is not particularly limited. Examples include a method of injecting the varnish composition into a mold of a desired shape, a method of filling the varnish composition into a mold using a squeegee, and a method of applying the varnish composition onto a base material. It will be done.
Among these methods, there is a method of applying a varnish composition onto a substrate because there is a large demand for polyimide resin films and it is easy to remove the solvent (S) from the varnish composition during polyimide resin production. is preferred.
After applying the varnish composition, the coated film is dried by heating and/or placed in a vacuum or reduced pressure environment to form a dry film.

The temperature at which the varnish composition or the varnish composition after the drying step is heated is not particularly limited as long as it is a temperature at which a polyimide resin with desired performance can be obtained. The temperature at which the polyamic acid is heated is preferably 120°C or more and 430°C or less, more preferably 150°C or more and 420°C or less. By heating the varnish composition at a temperature within such a range, the solvent (S) can be removed while suppressing thermal deterioration and thermal decomposition of the polyimide resin to be produced, and the polyimide resin can be produced.
In addition, since it is easy to form a polyimide resin with a high glass transition temperature and tensile strength, a low coefficient of thermal expansion, and little coloring, polyamic acid is heated at a temperature of 70°C or higher and 120°C or lower for about 10 minutes to 2 hours. It is also preferable to generate the polyimide resin by heating at a temperature of 150° C. or more and 420° C. or less for about 10 minutes to 2 hours while gradually increasing the temperature.

According to the method for producing polyimide resin described above, it is possible to produce polyimide resin with improved physical properties such as coefficient of thermal expansion, elongation at break, and tensile strength.

≪Additives≫
The additive is used in order to obtain a varnish composition for forming a polyimide resin by blending it into a polyamic acid-containing liquid containing a polyamic acid (A) and a solvent (S). The additive contains an amide compound (C). Regarding the additives, the polyamic acid (A), the solvent (S), and the amide compound (C) are as described above for the varnish composition. Further, the above-mentioned polyamic acid-containing liquid or the varnish composition to which the additives have been added may optionally contain the optional components described above for the varnish composition for forming a polyimide resin.
When heating a varnish composition containing the above additives to obtain a polyimide resin, the resulting polyimide resin has a lower coefficient of thermal expansion than when heating a polyamic acid-containing liquid to obtain a polyimide resin. At least one of an improvement in elongation at break and an improvement in tensile strength can be caused. Preferably, the use of additives results in a lower coefficient of thermal expansion, an increase in elongation at break, and an increase in tensile strength.

The form of the additive is not particularly limited. The additive may be in solid or liquid state. When the additive is in a solid state, the amide compound (C) is added to, for example, a colorant, a dispersant, a sensitizer, an adhesion promoter, an antioxidant, an ultraviolet absorber, an anti-aggregation agent, an antifoaming agent, and an interface agent. It may be mixed with at least one component selected from active agents and the like and processed into a form such as granules. Moreover, when the additive is a liquid, it is preferable to disperse or dissolve the amide compound (C) in the above-mentioned solvent (S). In addition to the amide compound (C), liquid additives include colorants, dispersants, sensitizers, adhesion promoters, antioxidants, ultraviolet absorbers, anti-aggregation agents, antifoaming agents, surfactants, etc. At least one selected component may be blended.

The amount of the additive used is not particularly limited as long as the desired effect can be obtained by using the additive. The amount of the additive used is such that the amount of the amide compound (C) contained in the additive is 1 part by mass or more and 40 parts by mass based on 100 parts by mass of the polyamic acid (A) contained in the polyamic acid-containing liquid. It is preferably at least 3 parts by mass and at most 30 parts by mass, and even more preferably at least 5 parts by mass and at most 25 parts by mass.
Moreover, the amide compound (C) and the thermal base generator (B) may be combined as additives, and the mass ratio of the thermal base generator (B) and the amide compound (C) ((B):(C) ) is, for example, 100:30 to 100:500, more preferably 100:100 to 100:300. The thermal base generator (B) is preferably a compound represented by the below-mentioned formula (B1), formula (B2), or formula (B4), more preferably a compound represented by formula (B4). .

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the scope of the present invention is not limited to these Examples.

[Preparation example 1]
First, a three-necked flask with a capacity of 30 mL was heated with a heat gun to thoroughly dry it. Next, the atmosphere inside the three-necked flask was replaced with nitrogen to create a nitrogen atmosphere inside the three-necked flask. After adding 0.2045 g of 4,4'-diaminobenzanilide (0.90 mmol: DABAN, manufactured by Nippon Junryaku Co., Ltd.) into a three-necked flask, N,N,N',N'-tetramethylurea (TMU ) was added. The contents of the three-necked flask were stirred to obtain a slurry liquid in which aromatic diamine (DABAN) was dispersed in TMU.
Next, 0.3459 g (0.90 mmol) of tetracarboxylic dianhydride of the following formula was added into the three-necked flask, and the contents of the flask were stirred at room temperature (25°C) for 12 hours under a nitrogen atmosphere. A reaction solution was obtained. In this way, a polyamic acid solution containing polyamic acid A-1 at a solid concentration of 18% by mass was obtained. The obtained polyamic acid A-1 provides a transparent polyimide resin.

[Preparation example 2]
Changing the diamine component to 4,4'-diaminodiphenyl ether, changing the tetracarboxylic dianhydride component to pyromellitic dianhydride, and changing the solvent to N-methyl-2-pyrrolidone (NMP). Otherwise, a polyamic acid solution containing polyamic acid A-2 at a solid concentration of 18% by mass was obtained in the same manner as in Preparation Example 1. The obtained polyamic acid A-2 provides an opaque polyimide resin.

[Examples 1 to 9]
A polyamic acid solution containing 80 parts by mass of polyamic acid (A) of the type listed in Table 1, 10 parts by mass of a thermal base generator (B) which is a compound having the following structure, and an amide compound ( After mixing with 10 parts by mass of C), the mixture was diluted to a solid content concentration of 15% by mass with the type of solvent (S) listed in Table 1 to obtain varnish compositions of Examples 1 to 9. Note that Example 4 shall be read as Reference Example 1.

[Comparative example 1]
After mixing a polyamic acid solution containing 80 parts by mass of polyamic acid A-1 and 20 parts by mass of the thermal base generator (B) used in the examples, the mixture was mixed with a solvent (S) of the type listed in Table 1. was diluted to a solid content concentration of 15% by mass to obtain a varnish composition of Comparative Example 1.

[Comparative example 2]
After mixing a polyamic acid solution containing 90 parts by mass of polyamic acid A-1 and 10 parts by mass of the thermal base generator (B) used in the examples, the mixture was mixed with the solvent (S) of the type listed in Table 1. was diluted to a solid content concentration of 15% by mass to obtain a varnish composition of Comparative Example 2.

[Comparative example 3]
A varnish composition of Comparative Example 3 was obtained by diluting a polyamic acid solution containing polyamic acid A-1 to a solid content concentration of 15% by mass with the type of solvent (S) listed in Table 1.

[Comparative example 4]
After mixing a polyamic acid solution containing 80 parts by mass of polyamic acid A-2 and 20 parts by mass of the thermal base generator (B) used in the examples, the mixture was mixed with a solvent (S) of the type listed in Table 1. was diluted to a solid content concentration of 15% by mass to obtain a varnish composition of Comparative Example 4.

Using the varnish compositions of each Example and Comparative Example obtained as described above, the storage stability of the varnish compositions was evaluated according to the following method. In addition, a polyimide resin was formed using the varnish composition after the storage stability evaluation, and the haze, yellowness index (YI), light transmittance, and coefficient of thermal expansion (CTE) of the formed polyimide resin were determined according to the following method. , elongation at break, and tensile strength were evaluated. It should be noted that the varnish composition of Comparative Example 1 could not be formed into a film due to thickening during storage, so no evaluation was performed on the polyimide resin.

<Storage stability>
The varnish compositions of each Example and Comparative Example prepared as described above were stored at 23° C. for 10 days, and the varnish compositions after storage were observed. A case in which neither cloudiness nor gelation occurred in the varnish after storage was evaluated as ○, and a case in which at least one of cloudiness and gelation occurred in the varnish was evaluated as ×.

For the varnish compositions of Examples 1 to 6, Comparative Example 2, and Comparative Example 3, polyimide resin films were formed as follows using the varnish compositions after being stored for a predetermined period.
<Polyimide resin film forming method>
On a glass substrate (length: 100 mm, width 100 mm, thickness 1.3 mm), the varnish composition obtained as described above after storage was spin coated so that the thickness of the coating after heat curing was 13 μm. A coating film was formed. Next, the glass substrate provided with the coating film was vacuum-dried under conditions of a temperature of 50° C. and a pressure of 13 Pa to remove the solvent in the coating film.
After removing the solvent, the glass substrate provided with the coating film was placed in an inert oven in which nitrogen was flowing at a flow rate of 3 L/min. In an inert oven, the coating film was left to stand at a temperature of 80°C for 0.5 hours under a nitrogen atmosphere, and then heated for an additional 0.5 hours at a temperature of 400°C (final heating temperature) to harden the coating film. A polyimide-coated glass coated with a thin film (polyimide film) made of polyimide was obtained.
The obtained polyimide coated glass was immersed in hot water at 90°C to peel the polyimide film from the glass substrate to obtain a polyimide film (film with dimensions of 100 mm long, 100 mm wide, and 13 μm thick).

<Haze, yellowness index (YI), light ray (total light ray) transmittance>
The haze, yellowness (YI), and total light transmittance (light transmittance) values (unit: %) of the polyimide films of each example and comparative example were measured using a measuring device manufactured by Nippon Denshoku Industries Co., Ltd. It was determined by measuring according to JIS K7361-1 (published in 1997) using the product name "Hazemeter NDH-5000".

<Coefficient of thermal expansion (CTE)>
A film for measurement measuring 20 mm in length and 5 mm in width was formed from the polyimide films of each example and comparative example.
Next, using a thermomechanical analyzer (product name "TMA-60" manufactured by Shimadzu Corporation) as a measuring device, the obtained film for measurement was heated at a heating rate of 10°C/10°C under a nitrogen atmosphere. When the temperature was raised from 30°C to 200°C under the conditions of 100°C to 200°C, the temperature was once cooled to 30°C, and then the temperature was raised again from 30°C to 500°C under the conditions of a heating rate of 10°C/min. The measurement was performed by measuring the change in length of the sample and calculating the average value of the change in length per 1°C from 100°C to 350°C. Note that the tensile mode was 49 mN.

<Elongation at break and tensile strength>
The polyimide films of each example and comparative example were placed in an SD lever-type sample cutter (cutting machine manufactured by Dumbbell Co., Ltd. (model SDL-200)) under the trade name "Super Dumbbell Cutter (model: SDMK-1000-D, conforming to A22 standard of JIS K7139 (published in 2009)", the size of the polyimide film is: total length: 75 mm, distance between tabs: 57 mm, length of parallel part: 30 mm, A dumbbell-shaped specimen (JIS K7139 type except for the thickness of 13 μm) was cut into pieces with shoulder radius: 30 mm, end width: 10 mm, central parallel width: 5 mm, and thickness: 13 μm. A test piece conforming to the A22 (scale test piece) standard was prepared as a measurement sample.
Next, using a Tensilon type universal testing machine (model number "UCT-10T" manufactured by A&D Co., Ltd.), the measurement sample was measured with a width between the grips of 57 mm and a width of the grip part of 10 mm (full width of the end). ) After arranging the test sample, a tensile test was conducted to pull the measurement sample under the conditions of a full scale load of 0.05 kN and a test speed of 1 to 300 mm/min to determine the tensile strength and elongation at break.
The above test is a test based on JIS K7162 (published in 1994).
In addition, the value of elongation at break (%) is determined by taking the length of the parallel part of the test piece (= length of the parallel part: 30 mm) as L0, and the length of the parallel part of the test piece until it breaks (when it breaks). The length of the parallel part of the test piece: 30 mm + α) is set to L, and the following formula:
[Elongation at break (%)] = {(L-L0)/L0} x 100
was calculated and obtained.

In Table 1 below, the types of amide compounds (C) are as follows.
C-1: Cinnamic acid amide C-2: Benzoic acid amide C-3: Phenylacetic acid amide C-4: Crotonamide C-5: N-methylacetamide C-6: 1,2,3-propanetricarboxamide

When comparing varnish compositions containing the same type of polyamic acid (A) in Examples and Comparative Examples, it is found that when the varnish composition contains the amide compound (C), the coefficient of thermal expansion of the polyimide resin formed using the varnish composition is It can be seen that the elongation at break and tensile strength increase.

Moreover, as can be seen from the comparative example, when the varnish composition did not contain the amide compound (C), clouding or gelation sometimes occurred when the varnish composition was stored at room temperature.
On the other hand, the varnish compositions of Examples containing the amide compound (C) were stable even when stored at room temperature for a certain period of time.

Furthermore, according to the evaluation results of the varnish compositions of Examples 1 to 6, Comparative Example 2, and Comparative Example 3, which contain polyamic acid A-1 that provides a transparent polyimide resin, Example 1 which contains the amide compound (C) It can be seen that by using the varnish compositions No. 6 to 6, it is possible to form a highly transparent polyimide resin with no clouding, little coloring, and high light transmittance.

Claims (10)

Contains a polyamic acid (A), an amide compound (C), and a solvent (S),
The amide compound (C) has the following formula (C1):
R ^c1 -(-CO-NH-R ^c2 ) _n ...(C1)
(In formula (C1), R ^c1 is an n-valent organic group bonded to a carbonyl group via a carbon-carbon bond, and is selected from a group including a saturated aliphatic group and an aryl group or a heteroaryl group. ( ^Rc2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n is an integer of 1 to 4.)
A varnish composition for forming polyimide resin, which is a compound represented by: The varnish composition according to claim 1, wherein the amide compound (C) includes a compound in which R ^c1 is a benzyl group and n is 1. Contains a polyamic acid (A), an amide compound (C), and a solvent (S),
The amide compound (C) has the following formula (C1):
R ^c1 -(-CO-NH-R ^c2 ) _n ...(C1)
(In formula (C1), R ^c1 is an n-valent organic group bonded to a carbonyl group via a carbon-carbon bond, and R ^c2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Yes, n is 3 or 4. )
A varnish composition for forming polyimide resin, which is a compound represented by : The varnish composition according to any one of claims 1 to 3, comprising a thermal base generator (B) that generates a basic nitrogen-containing heterocyclic compound by heating. The basic nitrogen-containing heterocyclic compound has the following formula (B1):

(In formula (B1), R ¹ , R ² , and R ³ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfonato group, (phosphino group, phosphinyl group, phosphonato group, or organic group)
The varnish composition according to claim 4, which is a compound represented by: The thermal base generator (B) has the following formula (B2):

(In formula (B2), R ¹ , R ² , and R ³ are the same as those in formula (B1) above, and R ^b1 and R ^b2 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, and a mercapto group. , a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, or an organic group, R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a mercapto group, a sulfide group, a silyl group, a silanol group, a nitro group, a nitroso group, a sulfino group, a sulfo group, a sulfonato group, and a phosphino group. , a phosphinyl group, a phosphono group, a phosphonato group, an amino group, an ammonio group, or an organic group, and R ^b3 , R ^b4 , R ^b5 , R ^b6 , and R ^b7 are two or more of them bonded together to form a cyclic structure. or may contain a heteroatom bond.)
A compound represented by and the following formula (B4):

(In formula (B4), R ¹ , R ² , and R ³ are the same as those in formula (B1) above, R ^b9 represents a hydrogen atom or a monovalent organic group, and R ^b10 represents a substituent represents an aromatic group which may have the following, and the R ^b9 may be bonded to the other R ^b9 or R ^b10 to form a cyclic structure.)
The varnish composition according to claim 5, which is one or more selected from the compounds represented by: The varnish composition according to any one of claims 1 to 6, wherein the content of the amide compound (C) is 1 part by mass or more and 40 parts by mass or less based on 100 parts by mass of the entire solid content. A molding step of molding the varnish composition according to any one of claims 1 to 7,
A method for producing a polyimide resin, including an imidization step of heating and imidizing the molded varnish composition. An additive used to obtain a varnish composition for forming a polyimide resin by blending it into a polyamic acid-containing liquid containing a polyamic acid (A) and a solvent (S),
the additive contains an amide compound (C),
The amide compound (C) has the following formula (C1):
R ^c1 -(-CO-NH-R ^c2 ) _n ...(C1)
(In formula (C1), R ^c1 is an n-valent organic group bonded to a carbonyl group via a carbon-carbon bond, and is selected from a group including a saturated aliphatic group and an aryl group or a heteroaryl group. ( ^Rc2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n is an integer of 1 to 4.)
It is a compound represented by
When heating the varnish composition to obtain a polyimide resin, the resulting polyimide resin has lower thermal expansion coefficient, improved elongation at break, and tensile strength compared to when heating the polyamic acid-containing liquid to obtain the polyimide resin. Additives that cause at least one of an increase in strength. An additive used to obtain a varnish composition for forming a polyimide resin by blending it into a polyamic acid-containing liquid containing a polyamic acid (A) and a solvent (S),
the additive contains an amide compound (C),
The amide compound (C) has the following formula (C1):
R ^c1 -(-CO-NH-R ^c2 ) _n ...(C1)
(In formula (C1), R ^c1 is an n-valent organic group bonded to a carbonyl group via a carbon-carbon bond, and R ^c2 is a hydrogen atom or an alkyl group having 1 or more and 6 or less carbon atoms, and n is 3 or 4. )
It is a compound represented by
When heating the varnish composition to obtain a polyimide resin, the resulting polyimide resin has lower thermal expansion coefficient, improved elongation at break, and tensile strength compared to when heating the polyamic acid-containing liquid to obtain the polyimide resin. Additives that cause at least one of an increase in strength.