JPWO2019074047A1 - Polyimide varnish composition, its manufacturing method, and polyimide film - Google Patents

Abstract

The present invention is a polyimide varnish composition containing a polyimide having a structural unit A derived from tetracarboxylic acid or a derivative thereof and a structural unit B derived from diamine and an organic solvent, wherein the structural unit A is 4. , 4'-(Hexafluoroisopropylidene) Containing a structural unit (A-1) derived from diphthalic acid anhydride, at least one organic solvent selected from lactone-based solvents is added to the total amount of the polyimide varnish composition. A polyimide varnish composition containing 20% by mass or more and having a YI of 20 or less measured in a cell having a light path length of 10 mm at 23 ° C., a method for producing the polyimide varnish composition, and the polyimide varnish composition. Provided are a polyimide varnish composition which is a polyimide film obtained from a product and can form a film having excellent colorless transparency, a method for producing the same, and a polyimide film obtained from the polyimide varnish composition.

Description

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

Generally, polyimide is obtained from aromatic tetracarboxylic acid anhydride and aromatic diamine, and has excellent heat resistance, chemical resistance, mechanical properties, and electrical properties due to molecular rigidity, resonance stabilization, and strong chemical bonds. , Molding materials, composite materials, electrical and electronic parts, optical materials, displays, aerospace, etc.
In recent years, properties such as colorless transparency and solvent solubility as polyimide have been required. However, conventional polyimides have problems such as many having a high haze value and a high yellow index (YI: yellowness).

For example, Patent Document 1 describes a polyimide produced by using a fluorinated diamine and a fluorinated acid anhydride, and containing a fluorinated polyimide layer having a haze value of 4 or less, a YI of 3 or less, and a total light transmittance of 90% or more. The film is disclosed.

Japanese Unexamined Patent Publication No. 2016-27146

However, the polyimide film of Patent Document 1 is produced through a step of purifying the fluorinated polyimide solution by a reprecipitation operation. Therefore, it is desired to improve the colorless transparency of the polyimide film by a simpler method.
That is, an object to be solved by the present invention is to provide a polyimide varnish composition capable of forming a film having excellent colorless transparency, a method for producing the same, and a polyimide film obtained from the polyimide varnish composition.

As a result of diligent studies by the inventors, the YI of the polyimide varnish composition containing a polyimide composed of a specific structural unit and a specific organic solvent is significantly reduced, and the polyimide film obtained from the varnish composition is obtained. It was found to be excellent in colorless transparency. The present invention was reached based on these findings. That is, the present invention relates to the following [1] to [3].
[1] A polyimide varnish composition containing a polyimide and an organic solvent.
The polyimide has a structural unit A derived from tetracarboxylic acid or a derivative thereof, and a structural unit B derived from diamine.
The structural unit A includes a structural unit (A-1) derived from a compound represented by the following formula (a-1).
20% by mass or more of at least one organic solvent selected from lactone-based solvents is contained in the total amount of the polyimide varnish composition.
A polyimide varnish composition having a YI of 20 or less measured in a cell having an optical path length of 10 mm at 23 ° C. of the polyimide varnish composition.

[2] A polyimide film obtained from the polyimide varnish composition.
[3] In the presence of at least one organic solvent selected from the lactone-based solvent and in the absence of a catalyst and a dehydrating agent, the diamine component and 4,4'-(hexafluoroisopropyridene) diphthalic acid or a derivative thereof are added. A method for producing a polyimide varnish composition containing a polyimide and an organic solvent by reacting with a tetracarboxylic acid component contained therein, wherein the content of the lactone-based solvent is 20% by mass based on the total amount of the polyimide varnish composition. The method for producing a polyimide varnish composition, wherein the YI measured in a cell having a light path length of 10 mm at 23 ° C. of the polyimide varnish composition is 20 or less.

According to the present invention, it is possible to provide a polyimide varnish composition capable of forming a film having excellent colorless transparency, a method for producing the same, and a polyimide film obtained from the polyimide varnish composition.

The polyimide varnish composition of the present invention contains a polyimide and an organic solvent. The polyimide varnish composition of the present invention may be simply abbreviated as "varnish composition".
Hereinafter, the polyimide varnish composition of the present invention will be described.

The polyimide contained in the varnish composition of the present invention has a structural unit A derived from tetracarboxylic acid or a derivative thereof, and a structural unit B derived from diamine, and the structural unit A is represented by the following formula (a-1). ) Includes a structural unit (A-1) derived from the compound.

[Constructive unit A]
The structural unit A contained in the polyimide according to the present invention is a structural unit derived from tetracarboxylic acid or a derivative thereof. The tetracarboxylic acid or a derivative thereof can be used alone or in combination of two or more.
Derivatives of tetracarboxylic acid include anhydrous or alkyl esters of tetracarboxylic acid. The alkyl ester of the tetracarboxylic acid preferably has 1 to 3 carbon atoms of the alkyl, and examples thereof include dimethyl ester, diethyl ester, and dipropyl ester of the tetracarboxylic acid. As the tetracarboxylic acid or a derivative thereof, tetracarboxylic acid dianhydride is preferable.

The structural unit A includes a structural unit (A-1) derived from the compound represented by the above formula (a-1). When the structural unit A includes the structural unit (A-1), the colorless transparency of the film is improved.
The ratio of the constituent unit (A-1) to the constituent unit A is preferably 30 mol% or more, more preferably 35 mol% or more, still more preferably 40 mol% or more, still more preferably 45 mol% or more, still more preferably. Is 50 mol% or more, and preferably 100 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less, still more preferably 80 mol% or less, still more preferably 70 mol% or less. Even more preferably, it is 60 mol% or less.

The structural unit A may further include a structural unit (A-2) derived from a compound represented by the following formula (a-2) from the viewpoints of heat resistance, mechanical properties (elastic modulus), and organic solvent resistance. preferable.

Examples of the compound represented by the formula (a-2) include 3,3', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) represented by the following formula (a-2-1). 2,3,3', 4'-biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a-2-2), 2 represented by the following formula (a-2-3) , 2', 3,3'-biphenyltetracarboxylic dianhydride (i-BPDA), among which 3,3', 4,4'-biphenyl represented by the following formula (a-2-1) Tetracarboxylic dianhydride is preferred. The compound represented by the formula (a-2) can be used alone or in combination of two or more.
s-BPDA is preferable in terms of organic solvent resistance, and a-BPDA and i-BPDA are preferable in terms of heat resistance and solution processability.

The ratio of the structural unit (A-2) to the structural unit A is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably, from the viewpoint of heat resistance, mechanical properties (elastic modulus), and organic solvent resistance. Is 20 mol% or more, more preferably 30 mol% or more, still more preferably 40 mol% or more. The ratio of (A-2) is preferably 70 mol% or less, more preferably 65 mol% or less, still more preferably 60 mol% or less, still more preferably 55 mol%, from the viewpoint of improving the colorless transparency of the film. Below, it is even more preferably 50 mol% or less.
When the structural unit A includes the structural unit (A-2), the molar ratio [(A-1) / (A-2)] between the structural unit (A-1) and the structural unit (A-2) is From the viewpoint of colorless transparency, heat resistance, and mechanical properties (elastic modulus), 30/70 to 95/5 is preferable, 35/65 to 90/10 is more preferable, and 40/60 to 80/20 is even more preferable. 45/55 to 70/30 is even more preferable, and 50/50 to 60/40 is even more preferable.

The ratio of the total of the structural unit (A-1) and the structural unit (A-2) in the structural unit A constituting the polyimide according to the present invention is preferably 70 to 100 mol%, more preferably 85 to 85. It is 100 mol%, more preferably 99 to 100 mol%, and even more preferably 100 mol%.
The polyimide according to the present invention has the above formula (a-1) as a structural unit other than the above structural units (A-1) and (A-2) in the structural unit A as long as the effects of the present invention are not impaired. And, a structural unit derived from a tetracarboxylic dianhydride other than the compound represented by (a-2) may be contained, but it is preferable that the structural unit is not contained.

[Constructive unit B]
The structural unit B contained in the polyimide according to the present invention is a structural unit derived from diamine. The diamine can be used alone or in combination of two or more.
The structural unit B preferably contains at least one selected from the group consisting of a structural unit derived from an aliphatic diamine and a structural unit derived from an aromatic diamine, and more preferably a structural unit derived from an aliphatic diamine. And contains building blocks derived from aromatic diamines.
By including a structural unit derived from an aliphatic diamine in the structural unit B, organic solvent resistance and colorless transparency are improved.
In the present invention, the "aliphatic diamine" represents a diamine in which an amino group is directly bonded to an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and an aliphatic group or an alicyclic is part of the structure thereof. It may contain a formula group, an aromatic group, and other substituents (for example, a halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.). “Aromatic diamine” refers to a diamine in which an amino group is directly bonded to an aromatic ring, and a part of its structure contains an aliphatic group, an alicyclic group, an aromatic group, and other substituents. You may. For example, m-xylylenediamine is an aliphatic diamine because the amino group is directly bonded to an aliphatic hydrocarbon group (methylene group).

As the structural unit derived from the aliphatic diamine, the structural unit (B-1) derived from the compound represented by the following formula (b-1) and the structural unit (B-2) derived from the following formula (b-2). ), And at least one selected from the group consisting of the structural unit (B-3) derived from the compound represented by the following formula (b-3), preferably derived from the following formula (b-2). It is more preferable to include the structural unit (B-2) to be used. When the structural unit B contains at least one selected from the group consisting of the structural units (B-1) and (B-2), the organic solvent resistance and colorless transparency are improved. When the structural unit B has the structural unit (B-3), mechanical properties (elastic modulus) and colorless transparency are improved.

The cis: trans ratio of the compounds represented by the formulas (b-1) and (b-2) is preferably 0: 100 to 100: 0, respectively, from the viewpoint of organic solvent resistance and heat resistance, respectively. 100 to 80:20 is more preferable, 0.1: 99.9 to 70:30 is more preferable, 0.5: 99.5 to 60:40 is even more preferable, and 1:99 to 20:80 is even more preferable. preferable.

The ratio of the total of the constituent units derived from the aliphatic diamine to the constituent unit B is preferably 10 to 95 mol%, more preferably 15 to 90 mol%, from the viewpoint of organic solvent resistance and colorless transparency. 20 to 80 mol% is more preferable, 35 to 75 mol% is further preferable, and 45 to 60 mol% is even more preferable.
The ratio of the total of the constituent units (B-1), (B-2) and (B-3) to the constituent units derived from the aliphatic diamine is 60 from the viewpoint of organic solvent resistance and colorless transparency. More than mol% is preferable, 80 mol% or more is more preferable, 90 mol% or more is further preferable, and 100 mol% is further preferable.

The structural unit derived from aromatic diamine preferably contains a structural unit (B-4) derived from a compound represented by the following formula (b-4) from the viewpoint of heat resistance and mechanical properties.

From the viewpoint of organic solvent resistance, the ratio of the constituent unit (B-4) to the constituent unit B is preferably 90 mol% or less, more preferably 85 mol% or less, still more preferably 80 mol% or less, still more preferably. Is 65 mol% or less, more preferably 55 mol% or less, and from the viewpoint of heat resistance and mechanical properties, preferably 1 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more, more. It is still more preferably 20 mol% or more, still more preferably 25 mol% or more, still more preferably 40 mol% or more.
The ratio of the structural unit (B-4) in the structural unit derived from aromatic diamine is preferably 60 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and further preferably 100 mol%. Is even more preferable.
The ratio of the total of the structural units derived from the aromatic diamine to the structural unit B is preferably 5 to 90 mol%, more preferably 10 to 85 mol% from the viewpoint of heat resistance, mechanical properties, and organic solvent resistance. Preferably, 20 to 80 mol% is more preferable, 25 to 65 mol% is further preferable, and 40 to 55 mol% is further preferable.
The ratio of the total of the structural units (B-1) to (B-4) to the structural unit B is preferably 70 to 100 mol%, more preferably 85 to 100 mol%, and further preferably 99 to 100 mol%. %, More preferably 100 mol%.
The polyimide according to the present invention contains a structural unit derived from a diamine other than the compounds represented by the formulas (b-1) to (b-4) in the structural unit B as long as the effect of the present invention is not impaired. It may be, but it is preferable that it is not contained.

[Method for manufacturing polyimide]
The polyimide is obtained by reacting a tetracarboxylic acid component that gives the structural unit A with a diamine component that gives the structural unit B.
Examples of the tetracarboxylic acid component that gives the structural unit A include tetracarboxylic acid or a derivative thereof. The tetracarboxylic acid component can be used alone or in combination of two or more.
Derivatives of the tetracarboxylic acid include anhydrous or alkyl esters of the tetracarboxylic acid.
The alkyl ester of the tetracarboxylic acid preferably has 1 to 3 carbon atoms of the alkyl, and examples thereof include dimethyl ester, diethyl ester, and dipropyl ester of the tetracarboxylic acid.
The tetracarboxylic acid component is essential to contain 4,4'-(hexafluoroisopropyridene) diphthalic acid or a derivative thereof, and preferably 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride [the above formula (the above formula). a-1)] is included.
Further, the tetracarboxylic acid component preferably contains a biphenyltetracarboxylic acid and a derivative thereof, and more preferably contains a biphenyltetracarboxylic acid dianhydride [formula (a-2) above], 3,3', 4 , 4'-biphenyltetracarboxylic acid dianhydride [the above formula (a-2-1)] is more preferably contained.

The amount of 4,4'-(hexafluoroisopropyridene) diphthalic acid or a derivative thereof used is preferably 30 to 100 mol%, more preferably 35 to 100 mol%, based on the total tetracarboxylic acid component from the viewpoint of colorless transparency. It is 95 mol%, more preferably 40 to 90 mol%, even more preferably 45 to 80 mol%, even more preferably 50 to 70 mol%, still more preferably 50 to 60 mol%.
The amount of biphenyltetracarboxylic acid and its derivative used is preferably 70 mol% or less, more preferably 5 with respect to the total tetracarboxylic acid component, from the viewpoints of heat resistance, mechanical properties (elastic modulus), and organic solvent resistance. It is ~ 65 mol%, more preferably 10-60 mol%, even more preferably 20-55 mol%, even more preferably 30-50 mol%, still more preferably 40-50 mol%.

Further, it contains 4,4'-(hexafluoroisopropyridene) diphthalic acid and its derivative, and a tetracarboxylic acid component other than biphenyltetracarboxylic acid and its derivative (hereinafter, also referred to as "other tetracarboxylic acid component"). You may.
Examples of other tetracarboxylic acid components include tetracarboxylic acid containing an aromatic ring or a derivative thereof, tetracarboxylic acid containing an alicyclic hydrocarbon structure or a derivative thereof, and the like. The other tetracarboxylic acid components can be used alone or in combination of two or more.
Examples of the tetracarboxylic acid containing an aromatic ring or a derivative thereof include pyromellitic acid, 3,3', 4,4'-diphenylsulfonetetracarboxylic acid, 3,3', 4,4'-benzophenone tetracarboxylic acid, 4, 4'-oxydiphthalic acid, 2,2', 3,3'-benzophenone tetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (2,3-dicarboxyphenyl) ) Propane, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane, 1,1-bis (2,3-dicarboxyphenyl) ethane, 1,2-bis (2,3-dicarboxyphenyl) Etan, 1,1-bis (3,4-dicarboxyphenyl) ethane, 1,2-bis (3,4-dicarboxyphenyl) ethane, bis (2,3-dicarboxyphenyl) methane, bis (3, 4-dicarboxyphenyl) methane, 4,4'-(p-phenylenedioxy) diphthalic acid, 4,4'-(m-phenylenedioxy) diphthalic acid, 2,3,6,7-naphthalenetetracarboxylic acid , 1,4,5,8-naphthalenetetracarboxylic acid, 2,3,5,6-toluenetetracarboxylic acid, and derivatives thereof.

Examples of the tetracarboxylic acid containing an alicyclic hydrocarbon structure or a derivative thereof include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,4,5-cyclopentanetetracarboxylic acid, 1,2,4. 5-Cyclohexanetetracarboxylic acid, bicyclo [2.2.2] octa-7-ene-2,3,5,6-tetracarboxylic acid, dicyclohexyltetracarboxylic acid, and cyclopentanone bisspironorbornanetetracarboxylic acid or these Positional isomers of, as well as derivatives thereof.
Examples of the tetracarboxylic acid having neither an alicyclic hydrocarbon structure nor an aromatic ring or a derivative thereof include 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-pentanetetracarboxylic acid and the like. Examples thereof include these derivatives.

The amount of the other tetracarboxylic acid components used is preferably 30 mol% or less, more preferably 15 mol% or less, still more preferably 1 mol% or less, still more preferably 0 mol%, based on the total tetracarboxylic acid components. Is.

The diamine component that gives the constituent unit B is not particularly limited, but preferably contains at least one selected from the group consisting of aliphatic diamines and aromatic diamines from the viewpoint of colorless transparency, heat resistance, and mechanical properties. , Aliphatic diamines, and aromatic diamines are more preferred. The diamine component that gives the structural unit B is not limited to diamine, and may be a derivative (diisocyanate or the like) as long as the same structural unit is formed, but diamine is preferable.
The aliphatic diamine preferably has 2 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and more preferably 6 to 8 carbon atoms.

Examples of the aliphatic diamine include hexamethylenediamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, and 1,3-bis (aminomethyl) cyclohexane [the above formula (b). -2)], 1,4-bis (aminomethyl) cyclohexane [the above formula (b-1)], m-xylylenediamine [the above formula (b-3)], paraxylylenediamine, 1,4-bis (the above formula (b-1)] 2-Amino-isopropyl) benzene, 1,3-bis (2-amino-isopropyl) benzene, isophoronediamine, norbornandiamine, siloxanediamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4, 4'-Diaminodicyclohexylmethane, 3,3'-diethyl-4,4'-diaminodicyclohexylmethane, 3,3', 5,5'-tetramethyl-4,4'-diaminodicyclohexylmethane, 2,3-bis (Aminomethyl) -bicyclo [2.2.1] heptane, 2,5-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) -bicyclo [2.2] .1] Heptane, 2,2-bis (4,4'-diaminocyclohexyl) propane, 2,2-bis (4,4'-diaminomethylcyclohexyl) propane and the like can be mentioned. These can be used alone or in combination of two or more.
Among the aliphatic diamines, 1,3-bis (aminomethyl) cyclohexane [the above formula (b-2)], 1,4-bis (aminomethyl) cyclohexane [the above formula (b-1)], m-xylylenedi. It preferably contains at least one selected from the group consisting of rangeamine [formula (b-3)], paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (amino). More preferably, it comprises at least one selected from the group consisting of methyl) cyclohexane and m-xylylenediamine, consisting of 1,3-bis (aminomethyl) cyclohexane and 1,4-bis (aminomethyl) cyclohexane. It is even more preferred to include at least one selected from the group, even more preferably to include 1,3-bis (aminomethyl) cyclohexane.

From the viewpoint of organic solvent resistance and colorless transparency, the total amount of the aliphatic diamine used is preferably 10 to 95 mol%, more preferably 15 to 90 mol%, and 20 to 80 mol% with respect to the total diamine component. Is even more preferable, 35 to 75 mol% is even more preferable, and 45 to 60 mol% is even more preferable.
The total amount of the aliphatic diamine represented by the formulas (b-1), (b-2) and (b-3) is the aliphatic diamine in the total diamine component from the viewpoint of organic solvent resistance and colorless transparency. With respect to the total amount of diamine, 60 mol% or more is preferable, 80 mol% or more is more preferable, 90 mol% or more is further preferable, and 100 mol% is further more preferable.
The amount of the aliphatic diamine other than the aliphatic diamine represented by the formulas (b-1), (b-2) and (b-3) is preferably 10 mol% or less based on the total diamine component. It is preferably 5 mol% or less, more preferably 1 mol% or less, and even more preferably 0 mol%.

Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, benzidine, o-trizine, m-trizine, and bis (trifluoromethyl) benzidine. [Formula (b-4) above], octafluorobenzidine, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro -4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,6-diaminonaphthalene, 1,5-diaminonaphthalene, 4,4'-diaminodiphenyl ether, 3,4' -Diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminobenzophenone, 2,2-bis (4- (4-amino) Phenoxy) phenyl) propane, 2,2-bis [4- (2-methyl-4-aminophenoxy) phenyl] propane, 2,2-bis [4- (2,6-dimethyl-4-aminophenoxy) phenyl] Propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 2,2-bis [4- (2-methyl-4-aminophenoxy) phenyl] hexafluoropropane, 2,2- Bis [4- (2,6-dimethyl-4-aminophenoxy) phenyl] hexafluoropropane, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (2-methyl-4-amino) Phenoxy) biphenyl, 4,4'-bis (2,6-dimethyl-4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] Sulfone, bis [4- (2-methyl-4-aminophenoxy) phenyl] sulfone, bis [4- (2,6-dimethyl-4-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) Phenyl] ether, bis [4- (2-methyl-4-aminophenoxy) phenyl] ether, bis [4- (2,6-dimethyl-4-aminophenoxy) phenyl] ether, 1,4-bis (4-) Aminophenoxy) benzene, 1,4-bis (2-methyl-4-aminophenoxy) benzene, 1,4-bis (2,6-dimethyl-4-aminophenoxy) benzene , 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (2-methyl-4-aminophenoxy) benzene, 1,3-bis (2,6-dimethyl-4-aminophenoxy) benzene, 1,4-Bis (4-amino-α, α-dimethylbenzyl) benzene,

2,2-bis (4-aminophenyl) propane, 2,2-bis (2-methyl-4-aminophenyl) propane, 2,2-bis (3-methyl-4-aminophenyl) propane, 2,2 -Bis (3-ethyl-4-aminophenyl) propane, 2,2-bis (3,5-dimethyl-4-aminophenyl) propane, 2,2-bis (2,6-dimethyl-4-aminophenyl) Propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis (2-methyl-4-aminophenyl) hexafluoropropane, 2,2-bis (2,6-dimethyl-4- Aminophenyl) Hexafluoropropane, α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (2-methyl-4-aminophenyl) -1,4-diisopropylbenzene , Α, α'-bis (2,6-dimethyl-4-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (3-aminophenyl) -1,4-diisopropylbenzene, α, α '-Bis (4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (2-methyl-4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (2, 6-Dimethyl-4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (3-aminophenyl) -1,3-diisopropylbenzene, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (2-methyl-4-aminophenyl) fluorene, 9,9-bis (2,6-dimethyl-4-aminophenyl) fluorene, 9,9-bis (3-fluoro-4-aminophenyl) ) Fluorene, 9,9-bis (3-methyl-4-aminophenyl) fluorene, 5-amino-1,3,3-trimethyl-1- (4-aminophenyl) -indane, 1,1-bis (4) -Aminophenyl) cyclopentane, 1,1-bis (2-methyl-4-aminophenyl) cyclopentane, 1,1-bis (2,6-dimethyl-4-aminophenyl) cyclopentane, 1,1-bis (4-Aminophenyl) cyclohexane, 1,1-bis (2-methyl-4-aminophenyl) cyclohexane, 1,1-bis (2,6-dimethyl-4-aminophenyl) cyclohexane, 1,1-bis ( 4-aminophenyl) 4-methyl-cyclohexane, 1,1-bis (4-aminophenyl) norbornan, 1,1-bi Su (2-methyl-4-aminophenyl) norbornane, 1,1-bis (2,6-dimethyl-4-aminophenyl) norbornane, 1,1-bis (4-aminophenyl) adamantane, 1,1-bis Examples thereof include (2-methyl-4-aminophenyl) adamantane and 1,1-bis (2,6-dimethyl-4-aminophenyl) adamantane. These can be used alone or in combination of two or more.
Among these, 2,2'-bis (trifluoromethyl) benzidine [the above formula (b-4)] is preferable from the viewpoint of heat resistance and mechanical properties.
From the viewpoint of organic solvent resistance, heat resistance, and mechanical properties, the amount of the aromatic diamine used is preferably 5 to 90 mol%, more preferably 10 to 85 mol%, and further preferably 20 with respect to the total diamine components. -80 mol%, more preferably 25-65 mol%, even more preferably 40-55 mol%.
The amount of the aromatic diamine other than 2,2'-bis (trifluoromethyl) benzidine used is preferably 20 mol% or less, more preferably 10 mol% or less, still more preferably 1 mol%, based on the total diamine component. Hereinafter, it is even more preferably 0 mol%.

When producing the polyimide according to the present invention, the charge amount ratio of the tetracarboxylic acid component and the diamine component is preferably 0.9 to 1.1 mol of the diamine component with respect to 1 mol of the tetracarboxylic acid component.

When producing the polyimide according to the present invention, an end-capping agent may be used in addition to the tetracarboxylic acid component and the diamine component. As the terminal encapsulant, monoamines or dicarboxylic acids are preferable. The amount of the terminal encapsulant to be introduced is preferably 0.0001 to 0.1 mol, more preferably 0.001 to 0.06 mol, based on 1 mol of the tetracarboxylic acid component. Examples of the monoamine terminal encapsulant include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-. Ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline and the like are recommended. Of these, benzylamine and aniline can be preferably used. As the dicarboxylic acid terminal encapsulant, dicarboxylic acids are preferable, and a part thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2 -Dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid and the like are recommended. Of these, phthalic acid and phthalic anhydride can be preferably used.

The method for reacting the above-mentioned tetracarboxylic acid component with the diamine component is not particularly limited, and a known method can be used.
As a specific reaction method, (1) a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, stirred at room temperature to 80 ° C. for 0.5 to 30 hours, and then heated to imidize. Method of carrying out the reaction, (2) After charging the diamine component and the reaction solvent into the reactor and dissolving them, the tetracarboxylic acid component is charged, and if necessary, the mixture is stirred at room temperature to 80 ° C. for 0.5 to 30 hours, and then. Examples thereof include a method of carrying out an imidization reaction by raising the temperature to (3) a method of charging a tetracarboxylic acid component, a diamine component and a reaction solvent into a reactor and immediately raising the temperature to carry out the imidization reaction.

The reaction solvent used for producing the polyimide may be one that does not inhibit the imidization reaction and can dissolve the produced polyimide, but is preferably a lactone-based solvent from the viewpoint of reducing the YI of the polyimide varnish composition of the present invention. At least one organic solvent selected from the solvents is selected. The above reaction solvent may be used alone or in combination of two or more.

Examples of the lactone-based solvent include γ-butyrolactone and γ-valerolactone, and among them, γ-butyrolactone is preferable.

A reaction solvent other than the lactone solvent may be used, but from the viewpoint of reducing the YI of the polyimide varnish composition, N, N-dimethylisobutylamide, N, N-dimethylformamide, N, N-dimethylacetamide, N -Methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, amide solvents such as tetramethylurea, amine solvents such as picolin and pyridine, and hexamethylphosphoric amide, hexamethylphosphintri It is preferable not to contain a phosphorus-containing amide solvent such as amide.
When an amide-based solvent, an amine-based solvent, a phosphorus-based amide-based solvent, or the like is contained in the reaction system as a reaction system solvent, the temperature rise in the imidization reaction raises the YI of the obtained varnish composition, and the polyimide film It is inevitable that the colorless transparency will decrease.

Examples of the reaction solvent other than the lactone-based solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, and 2,6-xylenol. Phenolic solvents such as 3,4-xylenol and 3,5-xylenol, sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide and sulfolane, ketone solvents such as acetone, cyclohexanone and methylcyclohexanone, acetic acid (2-methoxy-1). Ester solvent such as −methylethyl), 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy) ethyl) ] Examples include ether solvents such as ether, tetrahydrofuran and 1,4-dioxane, and carbonate solvents such as diethyl carbonate, methyl ethyl carbonate, ethylene carbonate and propylene carbonate. Of these, phenolic solvents are preferred.
The total content of the lactone-based solvent is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, still more preferably 90 to 100% by mass, based on the total amount of the reaction solvent used in the production of polyimide. It is 100% by mass.

In the imidization reaction, it is preferable to carry out the reaction while removing water generated during production by using a Dean-Stark apparatus or the like. By performing such an operation, the degree of polymerization and the imidization rate can be further increased.

In the reaction between the diamine component and the tetracarboxylic acid component, a polyimide solution containing at least polyimide and a reaction solvent can be obtained after the imidization reaction is completed.
In the reaction between the diamine component and the tetracarboxylic acid component, a catalyst, a dehydrating agent, etc. can be appropriately used as long as the effects of the present invention are not impaired, but the reaction is carried out under the condition that the catalyst and the dehydrating agent are not present. Is preferable. Among them, pyridine derivatives such as pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine, N, N-dimethylaniline, It is preferable to carry out the above imidization reaction without using a tertiary amine such as N, N-diethylaniline or triethylenediamine. In the present invention, by reacting the diamine component and the tetracarboxylic acid component in the absence of a catalyst and a dehydrating agent, imidization is performed in a shorter reaction time than when a tertiary amine such as triethylamine is used as an imidization catalyst. It was revealed that the reaction was completed and the YI of the obtained polyimide varnish composition was significantly reduced.

The temperature of the imidization reaction is preferably 120 to 350 ° C., more preferably 160 to 250 ° C., and even more preferably 170 to 190 ° C. from the viewpoint of improving the reaction rate and suppressing gelation and the like. The reaction time is preferably 0.5 to 10 hours, more preferably 1 to 8 hours, still more preferably 2 to 6 hours after the start of distillation of the produced water.

[Polyimide]
The weight average molecular weight of the polyimide according to the present invention is preferably 500 to 1,000,000, more preferably 5,000 to 100,000 from the viewpoint of the mechanical strength of the obtained polyimide film. The weight average molecular weight of polyimide can be measured by gel filtration chromatography or the like.
As an example of measuring the weight average molecular weight, there is a method of measuring the absolute molecular weight with a light scattering detector using N, N-dimethylformamide as a developing solvent.

[Polyimide varnish composition and its manufacturing method]
The polyimide varnish composition of the present invention contains the polyimide and the organic solvent according to the present invention. In the varnish composition of the present invention, the polyimide is dissolved in the organic solvent. The polyimide varnish composition of the present invention may be the polyimide solution itself obtained by reacting the above-mentioned diamine component with the tetracarboxylic acid component. Further, the polyimide solution may be mixed with at least one organic solvent selected from the dilution solvents described later.
The organic solvent contained in the varnish composition preferably contains at least the organic solvent used as the reaction solvent. The content of the organic solvent used as the reaction solvent is preferably 20% by mass or more, more preferably 22% by mass, based on the total amount of the polyimide varnish composition from the viewpoint of the solubility of the polyimide and the ease of processing into the polyimide film. As mentioned above, it is more preferably 24% by mass or more, preferably 50% by mass or less, and more preferably 40% by mass or less. The content of the lactone-based solvent contained in the varnish composition is 20% by mass or more, preferably 22% by mass or more, more preferably 24% by mass or more, and preferably 24% by mass or more, based on the total amount of the polyimide varnish composition. It is 50% by mass or less, more preferably 40% by mass or less.

The polyimide varnish composition of the present invention may be further mixed with various additives as long as the effects of the present invention are not impaired. Examples of the additive include an antioxidant, a light stabilizer, a surfactant, a flame retardant, a plasticizer, an inorganic filler, a polymer compound other than the polyimide, and the like.
Examples of the polymer compound include polyimides other than the polyimide according to the present invention, polycarbonates, polystyrenes, polyamides, polyamideimides, polyethylene terephthalates and other polyesters, polyethersulfones, polycarboxylic acids, polyacetals, polyphenylene ethers, polysulfones, polybutylenes, polypropylenes and polys. Examples thereof include acrylamide and polyvinyl chloride.

The solid content concentration of the polyimide varnish composition can be appropriately selected according to the workability and the like when forming the polyimide film described later, and the reaction solvent used for producing the polyimide according to the present invention is volatilized and condensed. Alternatively, the solid content concentration and viscosity of the polyimide varnish composition of the present invention may be adjusted by adding an organic solvent as a diluting solvent.
By adjusting the solid content concentration and viscosity of the polyimide varnish composition as described above, the thickness of the polyimide film according to the present invention described later can be easily controlled, and a polyimide film can be easily produced. ..

The diluting solvent is not particularly limited as long as it can dissolve the polyimide, but includes an amide solvent from the viewpoint of the solubility of the polyimide and the viewpoint of facilitating the removal of the solvent when processing the polyimide film. Is preferable.
Specific examples of amide-based solvents include N, N-dimethylisobutyramide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, and 1,3-dimethylimidazole. Examples thereof include lydinone and tetramethylurea. Of these, N, N-dimethylacetamide is preferable.
The content of the diluting solvent with respect to the total amount of the varnish composition is preferably 70% by mass or less, more preferably 65% by mass or less, still more preferably 60% by mass or less, and preferably 10% by mass or more and 20% by mass or more. , 25% by mass or more. The content of the amide-based solvent used as the diluting solvent contained in the varnish composition is also preferably in the same range as described above.
In the present invention, even when an amide-based solvent is used as the diluting solvent, the YI of the varnish composition can be reduced, and a polyimide having excellent colorless transparency can be produced.

The solid content concentration of the polyimide varnish composition of the present invention is not particularly limited, but is preferably 5 to 60% by mass, more preferably 10 to 45% by mass, further preferably 10 to 30% by mass, and 15 to 25% by mass. Even more preferable.
The viscosity of the polyimide varnish composition of the present invention at 25 ° C. is preferably 1 to 200 Pa · s, more preferably 5 to 150 Pa · s, still more preferably 10 to 100 Pa · s.
The yellow index (YI) of the polyimide varnish composition of the present invention can be preferably 20 or less, more preferably 15 or less, still more preferably 12 or less, still more preferably 10 or less. When the YI of the polyimide varnish composition is 20 or less, the YI of the polyimide film obtained from the polyimide varnish composition is reduced, and a polyimide film having excellent colorless transparency can be obtained. The YI of the polyimide varnish composition of the present invention is a value measured in a cell at 23 ° C. and an optical path length of 10 mm, and can be specifically measured by the method described in Examples. The solid content concentration when measuring the YI of the varnish composition is not particularly limited, but for example, it is preferable to use a varnish composition in which the solid content concentration is adjusted to 20% by mass.

The total content of the tertiary amine, the pyridine derivative, and the impurities derived from them contained in the polyimide varnish composition of the present invention is preferably 30 mass ppm or less, preferably 20 mass ppm or less, based on the polyimide. More preferably, it is more preferably 10 mass ppm or less. If the total content of the tertiary amine, the pyridine derivative, and the impurities derived from them contained in the polyimide varnish composition is 30 mass ppm or less, the polyimide varnish composition having a YI of 20 or less can be prepared. A polyimide film having excellent colorless transparency can be formed. The total content of the tertiary amine, the pyridine derivative, and the impurities derived from them contained in the polyimide varnish composition can be specifically measured by the method described in Examples. Examples of the tertiary amine and pyridine derivatives include the same as those exemplified above.
In the reaction between the diamine component and the tetracarboxylic acid component, it is common practice to use a tertiary amine or a pyridine derivative as an imidization catalyst, a dehydrating agent, a solvent or the like. Then, it is considered that a tertiary amine, a pyridine derivative or a compound derived from these is present as an impurity in the polyimide solution, and as a result, the YI of the varnish composition is deteriorated. In the present invention, from the viewpoint of reducing the YI of the varnish composition, by reacting the diamine component and the tetracarboxylic acid component without using a tertiary amine and a pyridine derivative, the tertiary contained in the polyimide varnish composition is contained. The total content of amines, pyridine derivatives, and impurities derived from them can be 30 mass ppm or less.

[Polyimide film]
The polyimide film of the present invention is characterized by being obtained from the polyimide varnish composition of the present invention, and is excellent in colorless transparency. The polyimide film of the present invention preferably comprises the polyimide contained in the polyimide varnish composition of the present invention.
The method for producing the polyimide film of the present invention is not particularly limited, and a known method can be used. For example, a method of applying the polyimide varnish composition of the present invention on a smooth support such as a glass plate, a metal plate, or plastic, or molding it into a film, and then removing the solvent component contained in the varnish composition. And so on.

A mold release agent may be applied to the surface of the support, if necessary. The following method is preferable as a method of applying the polyimide varnish composition to the support and then heating to remove the solvent component. That is, after evaporating the solvent component at a temperature of 120 ° C. or lower to form a self-supporting film, the self-supporting film is peeled off from the support, the end portion of the self-supporting film is fixed, and the solvent component used is used. It is preferable to produce a polyimide film by drying at a temperature equal to or higher than the boiling point of 350 ° C. or lower. Moreover, it is preferable to dry in a nitrogen atmosphere. The pressure in the dry atmosphere may be reduced pressure, normal pressure, or pressurized pressure.

The thickness of the polyimide film of the present invention can be appropriately selected depending on the intended use and the like, but is preferably in the range of 1 to 250 μm, more preferably 5 to 100 μm, and further preferably 10 to 90 μm. When the thickness is 1 to 250 μm, it can be practically used as a self-supporting film.
In the present invention, a polyimide film having a total light transmittance of 80 μm in thickness is preferably 80% or more, more preferably 85% or more, still more preferably 88% or more.
In the present invention, the polyimide film having a yellow index (YI) at a thickness of 80 μm is preferably 3.5 or less, more preferably 3.3 or less, still more preferably 3.1 or less, and even more preferably 2.6 or less. Can be done.
In the present invention, the polyimide film having a haze at a thickness of 80 μm is preferably 1.0% or less, more preferably 0.8% or less, still more preferably 0.7% or less, still more preferably 0.6% or less. Can be done.
The total light transmittance, YI, and haze of the polyimide film can be specifically measured by the method described in Examples.
In the present invention, when the total light transmittance of a polyimide film having a thickness of 80 μm is 80% or more, YI is 3.5 or less, and the haze is 1.0% or less, the polyimide film is excellent in colorless transparency. It can be said that. In other words, the polyimide film of the present invention preferably has a YI of 3.5 or less, a total light transmittance of 80% or more, and a haze of 1.0% or less as physical property values at a thickness of 80 μm.
In the present invention, a polyimide film having a glass transition temperature of preferably 200 ° C. or higher, more preferably 220 ° C. or higher, still more preferably 235 ° C. or higher, and even more preferably 250 ° C. or higher can be obtained.

The polyimide film obtained from the polyimide varnish composition of the present invention is suitably used as a film for various members such as color filters, flexible displays, semiconductor parts, and optical members.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to these examples.
The physical properties of the varnish composition and the polyimide film obtained in the following Examples and Comparative Examples were measured by the methods shown below.
(1) Total light transmittance, yellow index (YI), haze:
The total light transmittance, YI, and haze of the polyimide film were measured using a color / turbidity simultaneous measuring device "COH400" manufactured by Nippon Denshoku Industries Co., Ltd.
The YI of the varnish composition was calculated by placing the varnish composition in a 10 mm square quartz glass cell and measuring and calculating it at 23 ° C. in the same manner as described above.
The total light transmittance and YI measurements were based on JIS K7361-1: 1997, and the haze measurements were based on JIS K7136: 2000.
(2) Solid content concentration:
The solid content concentration of the polyimide varnish composition was calculated from the difference in sample weight before and after heating the sample in a small electric furnace MMF-1 manufactured by AS ONE Corporation at 300 ° C. × 30 min.
(3) Polyimide film thickness:
The polyimide film thickness was measured using a micrometer manufactured by Mitutoyo Co., Ltd.
(4) Viscosity of Polyimide Varnish Composition The viscosity of the polyimide varnish composition was measured at 25 ° C. using a viscometer TV-25 manufactured by Toki Sangyo Co., Ltd.
(5) Content of tertiary amines, pyridine derivatives, and impurities derived from them Total content of tertiary amines, pyridine derivatives, and impurities derived from them in the polyimide varnish composition (hereinafter, "specific impurity content" (Also referred to as)) was measured by analysis by the following method using gas chromatography (GC).
(GC analysis conditions)
Analysis was performed using a 7890A manufactured by Aglient Technology and a column DB-624 (length 30 m × inner diameter 0.25 mm, film thickness 1.4 μm) as a measuring device.
The term "below the detection limit" means that the content of specific impurities in polyimide is 30 mass ppm or less.

[Example 1]
Approximately 240 L of SUS reaction kettle equipped with stainless steel three-stage paddle stirring blade, 1,3-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemicals, Inc., hereinafter 1,3-BAC: solvent ratio 30) as a diamine component 5589 g and 2,2'-bis (trifluoromethyl) benzidine (manufactured by Wakayama Seika Kogyo Co., Ltd.) 12476 g, and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 61.44 kg as a reaction solvent were added. A solution was obtained by stirring under a nitrogen atmosphere at a system temperature of about 90 ° C. As a tetracarboxylic acid component, 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride (manufactured by Daikin Industries, Ltd.) 17333 g, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (Mitsubishi) After adding 11466 g (manufactured by Chemical Corporation) and 15000 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) as a reaction solvent, the temperature inside the reaction system was raised to 180 ° C. over about 80 minutes. The components to be distilled off were collected, the temperature inside the reaction system was maintained at 180 ° C., and the mixture was stirred for 5.25 hours to obtain a polyimide solution. Then, the temperature inside the reaction system was cooled to 120 ° C. to stop the reaction, and a total of 113,800 g of N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Company, Inc.) was added as a diluting solvent. The solution was stirred until it became uniform to obtain a polyimide varnish composition (A) having a solid content concentration of 16.5% by mass. The YI value of this polyimide varnish composition (A) was 6.3, the specific impurity content was below the detection limit, and the viscosity was 55.0 Pa · s.

Subsequently, the polyimide varnish composition (A) is applied onto a glass substrate, held at 60 ° C. for 30 minutes and at 100 ° C. for 1 hour, and the solvent is volatilized to obtain a colorless and transparent primary dry film having self-supporting property. Further, the film was fixed to a stainless steel frame and dried at 280 ° C. in a nitrogen atmosphere for 2 hours to remove the solvent, and a film having a thickness of 73 μm was obtained. FT-IR analysis of the obtained film confirmed the disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton. The total light transmittance of this polyimide film was 90.4%, the YI value was 2.6, and the haze was 0.2.

[Example 2]
Approximately 240 L of SUS reaction kettle equipped with stainless steel three-stage paddle stirring blade, 1,3-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemicals, Ltd., 1,3-BAC: solvent ratio 30%) as a diamine component ) 5589 g and 2,2'-bis (trifluoromethyl) benzidine (manufactured by Wakayama Seika Kogyo Co., Ltd.) 12476 g, and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 61.44 kg as a reaction solvent were added, and the temperature inside the system was about. A solution was obtained by stirring at 90 ° C. under a nitrogen atmosphere. As a tetracarboxylic acid component, 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride (manufactured by Daikin Industries, Ltd.) 17333 g, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (Mitsubishi) After adding 11466 g (manufactured by Chemical Corporation) and 15000 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) as a reaction solvent, the temperature inside the reaction system was raised to 180 ° C. over about 80 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 180 ° C. and the mixture was stirred for 4 hours to obtain a polyimide solution. Then, the temperature inside the reaction system was cooled to 120 ° C. to stop the reaction, and a total of 105870 g of N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Company, Inc.) was added. The solution was stirred until it became uniform to obtain a polyimide varnish composition (B) having a solid content concentration of 19.8% by mass. The YI value of this polyimide varnish composition (B) was 9.5, the specific impurity content was below the detection limit, and the viscosity was 47.7 Pa · s.

Subsequently, the polyimide varnish composition (B) is applied onto a glass substrate, held at 60 ° C. for 30 minutes and at 100 ° C. for 1 hour, and the solvent is volatilized to obtain a colorless and transparent primary dry film having self-supporting property. Further, the film was fixed to a stainless steel frame and dried at 280 ° C. in a nitrogen atmosphere for 2 hours to remove the solvent to obtain a film having a thickness of 80 μm. FT-IR analysis of the obtained film confirmed the disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton. The total light transmittance of this polyimide film was 90.3%, the YI value was 3.1, and the haze was 0.6.

[Comparative Example 1]
Approximately 240 L of SUS reaction kettle equipped with stainless steel three-stage paddle stirring blade, 1,3-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemicals, Ltd., 1,3-BAC: solvent ratio 30%) as a diamine component ) 5589 g and 2,2'-bis (trifluoromethyl) benzidine (manufactured by Wakayama Seika Kogyo Co., Ltd.) 12476 g, and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 61.44 kg as a reaction solvent were added, and the temperature inside the system was about. A solution was obtained by stirring at 90 ° C. under a nitrogen atmosphere. As a tetracarboxylic acid component, 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride (manufactured by Daikin Industries, Ltd.) 17333 g, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (Mitsubishi) After adding 11466 g (manufactured by Chemical Corporation) and 15000 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) as a reaction solvent, 394 g of triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as a catalyst, and the reaction system took about 80 minutes. The temperature was raised to 180 ° C. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 180 ° C. and the mixture was stirred for 9.5 hours to obtain a polyimide solution. Then, the temperature inside the reaction system was cooled to 120 ° C. to stop the reaction, and a total of 113,800 g of N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Company, Inc.) was added as a diluting solvent. The solution was stirred until it became uniform to obtain a polyimide varnish composition (C) having a solid content concentration of 18.5% by mass. The YI value of this polyimide varnish composition (C) was 56.1, the content of specific impurities was 330 mass ppm, and the viscosity was 50.2 Pa · s.

Subsequently, the polyimide varnish composition (C) was applied onto a glass substrate and held at 60 ° C. for 30 minutes and at 100 ° C. for 1 hour to volatilize the solvent to obtain a self-supporting primary dry film. The film was fixed to a stainless steel frame and dried at 280 ° C. under a nitrogen atmosphere for 2 hours to remove the solvent, and a film having a thickness of 76 μm was obtained. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. The total light transmittance of this polyimide film was 89.7%, the YI value was 5.8, and the haze was 0.4.

[Comparative Example 2]
Approximately 240 L of SUS reaction kettle equipped with stainless steel three-stage paddle stirring blade, 1,3-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemicals, Ltd., 1,3-BAC: solvent ratio 30%) as a diamine component ) 5589 g and 2,2'-bis (trifluoromethyl) benzidine (manufactured by Wakayama Seika Kogyo Co., Ltd.) 12476 g, and γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 61.44 kg as a reaction solvent were added, and the temperature inside the system was about. A solution was obtained by stirring at 90 ° C. under a nitrogen atmosphere. As a tetracarboxylic acid component, 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride (manufactured by Daikin Industries, Ltd.) 17333 g, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (Mitsubishi) After adding 11466 g (manufactured by Chemical Corporation) and 15000 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) as a reaction solvent, 236 g of triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as a catalyst, and the reaction system took about 80 minutes. The temperature was raised to 180 ° C. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 180 ° C. and the mixture was stirred for 8 hours to obtain a polyimide solution. Then, the temperature inside the reaction system was cooled to 120 ° C. to stop the reaction, and a total of 113240 g of N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Company, Inc.) was added as a diluting solvent. The solution was stirred until it became uniform to obtain a polyimide varnish composition (D) having a solid content concentration of 18.7% by mass. The YI value of this polyimide varnish composition (D) was 36.1, the specific impurity content was 300 mass ppm, and the viscosity was 49.5 Pa · s.

Subsequently, the polyimide varnish composition (D) was applied onto a glass substrate and held at 60 ° C. for 30 minutes and at 100 ° C. for 1 hour to volatilize the solvent to obtain a self-supporting primary dry film. The film was fixed to a stainless steel frame and dried at 280 ° C. under a nitrogen atmosphere for 2 hours to remove the solvent, and a film having a thickness of 80 μm was obtained. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. The total light transmittance of this polyimide film was 89.6%, the YI value was 5.6, and the haze was 0.5.

The abbreviations in the table are as follows.
6FDA: 4,4'-(hexafluoroisopropylidene) diphthalic anhydride [compound represented by formula (a-1)]
s-BPDA: 3,3', 4,4'-biphenyltetracarboxylic dianhydride [compound represented by formula (a-2-1)]
1,3-BAC: trans ratio 30%: 1,3-bis (aminomethyl) cyclohexane [Cis: trans = 70:30 (molar ratio) compound represented by formula (b-2)]
TFMB: 2,2'-bis (trifluoromethyl) benzidine [compound represented by formula (b-4)]
GBL: γ-Butyrolactone DMAc: N, N-dimethylacetamide TEA: triethylamine

From Table 1, since the YI of the polyimide varnish compositions of Examples 1 and 2 was low, the YI and haze of the polyimide film were low, and the total light transmittance was high, a polyimide film having excellent colorless transparency could be formed. I understand. On the other hand, the polyimide varnish compositions and the polyimide films of Comparative Examples 1 and 2 had a high YI, and the colorless transparency of the polyimide film could not be improved.

Claims (17)

A polyimide varnish composition containing a polyimide and an organic solvent.
The polyimide has a structural unit A derived from tetracarboxylic acid or a derivative thereof, and a structural unit B derived from diamine.
The structural unit A includes a structural unit (A-1) derived from a compound represented by the following formula (a-1).
20% by mass or more of at least one organic solvent selected from lactone-based solvents is contained in the total amount of the polyimide varnish composition.
A polyimide varnish composition having a YI of 20 or less measured in a cell having an optical path length of 10 mm at 23 ° C. of the polyimide varnish composition.

The polyimide varnish composition according to claim 1, wherein the total content of the tertiary amine, the pyridine derivative, and the impurities derived from them is 30 mass ppm or less with respect to the polyimide. The polyimide varnish composition according to claim 1 or 2, wherein the structural unit B contains at least one selected from the group consisting of a structural unit derived from an aliphatic diamine and a structural unit derived from an aromatic diamine. The polyimide varnish composition according to any one of claims 1 to 3, wherein the structural unit B contains a structural unit derived from an aliphatic diamine and a structural unit derived from an aromatic diamine. The constitutional unit derived from the aliphatic diamine is a constitutional unit (B-1) derived from a compound represented by the following formula (b-1) and a constitution derived from a compound represented by the following formula (b-2). The third or fourth claim, which comprises at least one selected from the group consisting of the unit (B-2) and the structural unit (B-3) derived from the compound represented by the following formula (b-3). Polyimide varnish composition.

The polyimide varnish composition according to any one of claims 3 to 5, wherein the structural unit derived from the aromatic diamine contains a structural unit (B-4) derived from a compound represented by the following formula (b-4). object.

The polyimide varnish composition according to any one of claims 1 to 6, wherein the structural unit A further contains a structural unit (A-2) derived from a compound represented by the following formula (a-2).

The polyimide varnish composition according to any one of claims 1 to 7, wherein the ratio of the structural unit (A-1) to the structural unit A is 30 mol% or more. The polyimide varnish composition according to any one of claims 3 to 8, wherein the ratio of the structural unit derived from the aliphatic diamine to the structural unit B is 10 to 95 mol%. The polyimide varnish composition according to any one of claims 3 to 9, wherein the ratio of the structural unit derived from the aromatic diamine to the structural unit B is 5 to 90 mol%. The polyimide varnish composition according to any one of claims 1 to 10, wherein the content of the amide-based solvent with respect to the total amount of the polyimide varnish composition is 70% by mass or less. A polyimide film obtained from the polyimide varnish composition according to any one of claims 1 to 11. The polyimide film according to claim 12, wherein the polyimide film having a thickness of 80 μm has a YI of 3.5 or less, a total light transmittance of 80% or more, and a haze of 1.0% or less. A tetracarboxylic containing a diamine component and 4,4'-(hexafluoroisopropyridene) diphthalic acid or a derivative thereof in the presence of at least one organic solvent selected from the lactone-based solvent and in the absence of a catalyst and a dehydrating agent. A method for producing a polyimide varnish composition containing a polyimide and an organic solvent by reacting with an acid component, wherein the content of the lactone-based solvent is 20% by mass or more with respect to the total amount of the polyimide varnish composition. A method for producing a polyimide varnish composition, wherein the YI measured in a cell having an optical path length of 10 mm at 23 ° C. of the polyimide varnish composition is 20 or less. A tetracarboxylic containing a diamine component and 4,4'-(hexafluoroisopropyridene) diphthalic acid or a derivative thereof in the presence of at least one organic solvent selected from the lactone-based solvent and in the absence of a catalyst and a dehydrating agent. The method for producing a polyimide varnish composition according to claim 14, wherein a polyimide solution is obtained by reacting with an acid component, and a polyimide varnish composition is obtained by mixing the obtained polyimide solution and a diluting solvent. The method for producing a polyimide varnish composition according to claim 15, wherein the diluting solvent contains an amide-based solvent. The method for producing a polyimide varnish composition according to any one of claims 14 to 16, wherein the reaction temperature is 170 to 190 ° C.