TW201918506A - Polyimide, polyimide varnish and polyimide film - Google Patents

Abstract

This invention provides a polyimide having a constituting unit A that comprises a constituting unit (A-1) derived from a compound represented by the formula (a-1) and a constituting unit (A-2) derived from a compound represented by the formula (a-2), and a constituting unit B that comprises a constituting unit (B-1) derived from a compound represented by the formula (b-1) and a constituting unit (B-2) derived from a compound represented by the formula (b-2). This polyimide can form a polyimide varnish and a polyimide film containing the polyimide, wherein the film has a low linear thermal expansion coefficient while maintaining high transparency and high heat resistance. This invention also provides a polyimide varnish and a polyimide film containing the polyimide. (In the formula (b-1), each R independently represents a hydrogen atom, a fluorine atom or a methyl group.).

Description

Polyimide, polyimide varnish, and polyimide film

The present invention relates to polyimide, and polyimide varnish and polyimide film containing the polyimide.

In addition to its excellent heat resistance, polyimide has excellent properties such as mechanical properties, chemical resistance, and electrical properties. Therefore, polyimide-based films are widely used in molding materials, composite materials, and electrical- Electronic parts and display devices.
In the field of display devices, research is being actively conducted to reduce the weight, thickness, and flexibility of display devices by using plastic substrates instead of glass substrates. However, for example, when an electronic component made of an inorganic material is formed on a thin film, since the linear thermal expansion coefficient of the inorganic material and the thin film are significantly different, the thin film formed with the electronic component made of an inorganic material may be bent or even made of an inorganic material. When electronic components made of materials are peeled from the film. Therefore, in addition to transparency and heat resistance, a polyimide film is required to have a low linear thermal expansion coefficient.

Generally speaking, it is known that the polymer chain of polyimide is rigid, and the higher the linearity, the lower the linear thermal expansion coefficient. Therefore, in order to reduce the linear thermal expansion coefficient of polyimide and improve dimensional stability, various structures have been proposed for both acid dianhydride and diamine which are raw materials of polyimide.

For example, Patent Document 1 discloses that 4,4 '-(hexafluoroisopropylidene) diphthalic acid is used as an acid component, and 4,4'-diamino-2,2'-bis (trifluoro Poly (methyl) biphenyl is used as a diamine component.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2012-503701

[Problems to be Solved by the Invention]

However, although the polyimide disclosed in Patent Document 1 is excellent in transparency and heat resistance, the linear thermal expansion coefficient has not reached a satisfactory level, and further improvement is necessary.
That is, the subject to be solved by the present invention is to provide a polyimide which can form a thin film having a low linear thermal expansion coefficient while maintaining high transparency and high heat resistance, and a polyimide varnish containing the polyimide. And polyimide film.
[Means for solving problems]

As a result of intensive research by the inventors, it was found that polyimide having a specific constituent unit can form a thin film having a low linear thermal expansion coefficient while maintaining high transparency and high heat resistance. The present invention has been completed based on these findings. That is, the present invention relates to the following [1] to [3].
[1] A polyfluorene imide having a constitutional unit A derived from a tetracarboxylic acid or a derivative thereof, and a constitutional unit B derived from a diamine;
The structural unit A contains a structural unit (A-1) derived from a compound represented by the following formula (a-1), and a structural unit (A-2) derived from a compound represented by the following formula (a-2);
The structural unit B contains a structural unit (B-1) derived from a compound represented by the following formula (b-1) and a structural unit (B-2) derived from a compound represented by the following formula (b-2).

[Chemical 1]
[Chemical 2]

In formula (b-1), R each independently represents a hydrogen atom, a fluorine atom, or a methyl group.
[2] A polyimide varnish obtained by dissolving the polyimide of [1] in an organic solvent.
[3] A polyimide film, comprising the polyimide of [1].
[Effect of the invention]

According to the present invention, it is possible to provide a polyimide capable of forming a thin film that maintains high transparency and high heat resistance while having a low linear thermal expansion coefficient, and a polyimide varnish and a polyimide film containing the polyimide. .

[Polyimide]
The polyimide of the present invention is the following polyimide:
Has a constitutional unit A derived from a tetracarboxylic acid or a derivative thereof, and a constitutional unit B derived from a diamine,
And the constitutional unit A contains a constitutional unit (A-1) derived from the compound represented by the above formula (a-1) and a constitutional unit (A-2) derived from the compound represented by the above formula (a-2),
The structural unit B contains a structural unit (B-1) derived from the compound represented by the above formula (b-1), and a structural unit (B-2) derived from the compound represented by the above formula (b-2). The polyimide of the present invention can be formed to have a low line by having specific structural units (A-1), structural units (A-2), structural units (B-1), and structural units (B-2). Thermal expansion coefficient film.

[Construction unit A]
The constitutional unit A contained in the polyfluorene imine of the present invention is a constitutional unit derived from a tetracarboxylic acid or a derivative thereof. The tetracarboxylic acid or a derivative thereof may be used alone or in combination of two or more kinds.
Examples of the derivative of the tetracarboxylic acid include anhydrides or alkyl esters of the tetracarboxylic acid. As for the alkyl ester of a tetracarboxylic acid, the carbon number of the alkyl group is preferably 1 to 3, and examples thereof include dimethyl, diethyl, and dipropyl esters of the tetracarboxylic acid. The tetracarboxylic acid or a derivative thereof is preferably a tetracarboxylic dianhydride.
The constitutional unit A in the present invention contains a constitutional unit (A-1) derived from a compound represented by the following formula (a-1). The compound represented by formula (a-1) is biphenyltetracarboxylic dianhydride. When the structural unit A contains the structural unit (A-1), the heat resistance, mechanical properties (elastic modulus), and organic solvent resistance of the polyimide are improved.

[Chemical 3]

Examples of the compound represented by the formula (a-1) include 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) represented by the following formula (a-1-1), and the following formula (a -1-2) represented by 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride (a-BPDA), and 2,2', 3,3 represented by the following formula (a-1-3) The '-biphenyltetracarboxylic dianhydride (i-BPDA) is preferably 3,3', 4,4'-biphenyltetracarboxylic dianhydride represented by the following formula (a-1-1). The compound represented by formula (a-1) can be used alone or in combination of two or more kinds.
s-BPDA is preferred from the viewpoint of resistance to organic solvents, and a-BPDA and i-BPDA are preferred from the viewpoint of heat resistance and solution processability.

[Chemical 4]

The ratio of the constituent unit (A-1) to the constituent unit A is preferably 50 mol% or more, and more preferably 55 mol% or more, in view of heat resistance, mechanical properties (elastic modulus), and resistance to organic solvents. It is more preferably 60 mol% or more, more preferably 65 mol% or more, and even more preferably 70 mol% or more, and preferably 99 mol% or less, more preferably 95 mol% or less, particularly preferably It is 90 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less.

The structural unit A contains a structural unit (A-2) derived from a compound represented by the following formula (a-2). The compound represented by the formula (a-2) is 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride. By containing the structural unit (A-2) in the structural unit A, the transparency of the film is improved, and the solubility of the polyimide in an organic solvent is improved.

[Chemical 5]

The ratio of the constituent unit (A-2) to the constituent unit A is preferably 1 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more in consideration of solubility and high transparency. It is more preferably 15 mol% or more, and even more preferably 20 mol% or more. In view of high heat resistance, it is preferably 50 mol% or less, more preferably 45 mol% or less, and particularly preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less.

The ratio of the constituent unit (A-1) and the constituent unit (A-2) to the constituent unit A is preferably 50 to 99 mol% of the constituent unit (A-1), and 1 to 1 of the constituent unit (A-2). 50 mol%, more preferably 55 to 95 mol% of the structural unit (A-1), 5 to 45 mol% of the structural unit (A-2), and particularly preferably 60 of the structural unit (A-1) ～ 90 mol%, the constituent unit (A-2) is 10 to 40 mol%, and more preferably, the constituent unit (A-1) is 65 to 85 mol%, and the constituent unit (A-2) is 15 to 35 mol%, and particularly preferably, the constituent unit (A-1) is 70 to 80 mol%, and the constituent unit (A-2) is 20 to 30 mol%.
The molar ratio [(A-1) / (A-2)] of the constituent unit (A-1) and the constituent unit (A-2) is preferably 50/50 in view of low linear thermal expansion coefficient and high transparency. ～ 99/1, more preferably 55/45 ～ 95/5, more preferably 60/40 ～ 90/10, more preferably 65/35 ～ 85/15, and even more preferably 70/30 ～ 80/20 .

As for the polyimide of the present invention, as long as the effect of the present invention is not impaired, the constituent unit A may contain a compound derived from the formula (a-1) and a compound represented by the formula (a-2). The constituent units other than the tetracarboxylic acid or a derivative thereof are the constituent units other than the aforementioned constituent unit (A-1) and the constituent unit (A-2), but are preferably not included.
The proportion of the total of the constituent unit (A-1) and the constituent unit (A-2) in the constituent unit A is preferably 70 mol% from the viewpoint of low linear thermal expansion coefficient, high transparency, and resistance to organic solvents. Above, it is more preferably 85 mol% or more, more preferably 99 mol% or more, and even more preferably 100 mol%.

[Construction unit B]
The structural unit B contained in the polyfluorene imine of the present invention is a structural unit derived from a diamine.
The aforementioned constitutional unit B contains a constitutional unit (B-1) derived from a compound represented by the following formula (b-1).

[Chemical 6]

In the above formula (b-1), each R is independently selected from the group consisting of a hydrogen atom, a fluorine atom, and a methyl group, and is preferably a hydrogen atom.
Examples of the compound represented by the above formula (b-1) include 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (3-fluoro-4-aminophenyl) fluorene, and 9, 9-bis (3-methyl-4-aminophenyl) fluorene and the like, preferably at least one selected from the group consisting of these three compounds, is 9,9-bis (4-aminobenzene Basic) 茀 is better.
By containing the said structural unit (B-1), the polyimide of this invention improves transparency and heat resistance.
In the present invention, the ratio of the constituent unit (B-1) to the constituent unit B is preferably 50 mol% or less, more preferably 40 mol% or less, and more preferably 35 mol in consideration of a low linear thermal expansion coefficient. % Or less, more preferably 30 mol% or less, and even more preferably 25 mol% or less, and in view of high transparency and high heat resistance, it is preferably 5 mol% or more, and more preferably 10 mol % Or more, particularly preferably 15 mol% or more, and more preferably 20 mol% or more.

The constitutional unit B in the present invention contains a constitutional unit (B-2) derived from a compound represented by the following formula (b-2).

[Chemical 7]

The compound represented by the above formula (b-2) is 2,2'-bis (trifluoromethyl) benzidine (alias: 4,4'-diamino-2,2'-bis (trifluoromethyl) benzidine benzene).
By containing the aforementioned structural unit (B-2), the polyimide of the present invention can form a film having improved mechanical properties (elastic modulus) and a low linear thermal expansion coefficient.
In the present invention, the ratio of the aforementioned structural unit (B-2) to the structural unit B is preferably 50 mol% or more in consideration of the viewpoint of forming a thin film having high transparency and high heat resistance while having a low linear thermal expansion coefficient. More preferably, it is 60 mol% or more, more preferably 65 mol% or more, even more preferably 70 mol% or more, even more preferably 75 mol% or more, and more preferably 95 mol% or less, more preferably 90 mol% or less, particularly preferably 85 mol% or less, and even more preferably 80 mol% or less.

The proportion of the constituent units (B-1) and (B-2) to the constituent unit B is preferably 5 to 50 mole% of the constitution unit (B-1) and 50 to 95 moles of the constitution unit (B-2). Ear%, more preferably 10 to 40 mol% of the constituent unit (B-1), 60 to 90 mol% of the constituent unit (B-2), and most preferably 15 to 35 of the constituent unit (B-1) Molar%, 65-85 Molar% of the constituent unit (B-2), more preferably 15-30 Molar% of the constituent unit (B-1), and 70-85 Molar of the constituent unit (B-2) The ear unit is particularly preferably 20 to 25 mole% of the constituent unit (B-1) and 75 to 80 mole% of the constituent unit (B-2).
The molar ratio [(B-1) / (B-2)] of the constituent unit (B-1) and the constituent unit (B-2) is considered to maintain high transparency and high heat resistance, and at the same time have a low linear thermal expansion coefficient From the viewpoint of the film, it is preferably 50/50 to 5/95, more preferably 40/60 to 10/90, more preferably 35/65 to 15/85, and still more preferably 30/70 to 15/85. 25/75 ～ 20/80 is even better.

In the polyfluorene imide of the present invention, as long as the effect of the present invention is not impaired, the constituent unit B may contain diamines other than the compounds represented by the formulae (b-1) to (b-2). Components, but should not be included.
The proportion of the total of the constituent unit (B-1) and the constituent unit (B-2) in the constituent unit B should be considered from the viewpoint of forming a thin film that maintains high transparency and high heat resistance and has a low linear thermal expansion coefficient. It is 70 mol% or more, more preferably 85 mol% or more, more preferably 99 mol% or more, and 100 mol% or more.

[Manufacturing method of polyimide]
The polyfluorene imide of the present invention is obtained by reacting a tetracarboxylic acid component that provides the structural unit A and a diamine component that provides the structural unit B.

Examples of the tetracarboxylic acid component include tetracarboxylic acid or a derivative thereof. The tetracarboxylic acid component can be used alone or in combination of two or more.
Examples of the tetracarboxylic acid derivatives include anhydrides or alkyl esters of the tetracarboxylic acids.
As for the alkyl ester of a tetracarboxylic acid, the carbon number of the alkyl group is preferably 1 to 3, and examples thereof include dimethyl, diethyl, and dipropyl esters of the tetracarboxylic acid.
The tetracarboxylic acid component used in the present invention contains biphenyltetracarboxylic acid or a derivative thereof, and 4,4 ′-(hexafluoroisopropylidene) diphthalic acid or a derivative thereof. Among these, biphenyltetracarboxylic dianhydride [formula (a-1)] and 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride [formula (a-2)] are preferably contained, Contains 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride [Formula (a-1-1)] and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride Better.

The amount of biphenyltetracarboxylic acid or its derivative is preferably 50 to 99 mol%, more preferably 55 to 95 mol%, and even more preferably 60 to 90 mol% relative to the total tetracarboxylic acid component. More preferably, it is 65 to 85 mol%, and even more preferably, it is 70 to 80 mol%.
The amount of 4,4 '-(hexafluoroisopropylidene) diphthalic acid or its derivative is preferably 1 to 50 mol%, more preferably 5 to 45 mol, relative to the total tetracarboxylic acid component. %, Particularly preferably 10 to 40 mole%, even more preferably 15 to 35 mole%, and even more preferably 20 to 30 mole%.
The total amount of biphenyltetracarboxylic acid, 4,4 '-(hexafluoroisopropylidene) diphthalic acid, and their derivatives is preferably 70 to 100 moles relative to the total tetracarboxylic acid component. %, More preferably 85 to 100 mole%, even more preferably 99 to 100 mole%, and even more preferably 100 mole%.

Furthermore, the tetracarboxylic acid component used in the present invention may also contain tetraphenylcarboxylic acid other than biphenyltetracarboxylic acid, 4,4 '-(hexafluoroisopropylidene) diphthalic acid, or derivatives thereof. Acid component. The tetracarboxylic acid component includes at least one selected from the group consisting of an aromatic ring-containing tetracarboxylic acid or a derivative thereof, and an alicyclic hydrocarbon structure-containing tetracarboxylic acid or a derivative thereof. This tetracarboxylic acid component can be used individually or in combination of 2 or more types.

Examples of tetracarboxylic acids or derivatives containing aromatic rings include pyromellitic acid, 3,3 ', 4,4'-diphenylarsinetetracarboxylic 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-di Carboxyphenyl) ethane, 1,2-bis (2,3-dicarboxyphenyl) ethane, 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-phenylene dioxy) diphthalic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalene tetra Carboxylic acids and their derivatives.

Examples of tetracarboxylic acids or their derivatives containing alicyclic hydrocarbon structures include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,4,5-cyclopentanetetracarboxylic acid, 1,2 , 4,5-cyclohexanetetracarboxylic acid, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid, dicyclohexyltetracarboxylic acid, cyclopentanone dispiroline Alkyltetracarboxylic acids or their positional isomers, and their derivatives.
Examples of the tetracarboxylic acid or its derivative which does not contain any of an alicyclic hydrocarbon structure and an aromatic ring include 1,2,3,4-butanetetracarboxylic acid and 1,2,3,4-pentane Tetracarboxylic acids and the like or their derivatives.

The amount of the tetracarboxylic acid component other than biphenyltetracarboxylic acid or its derivative and 4,4 '-(hexafluoroisopropylidene) diphthalic acid or its derivative is used relative to the total tetracarboxylic acid component It is preferably 30 mol% or less, more preferably 15 mol% or less, even more preferably 1 mol% or less, and still more preferably 0 mol%.

The diamine component used in the present invention contains a compound represented by the above formula (b-1) and 2,2'-bis (trifluoromethyl) benzidine [the above formula (b-2)]. In addition, the diamine component providing the constituent unit B is not limited to the diamine, and may be a derivative thereof (diisocyanate, etc.) as long as it can form the same constituent unit, but it is preferably a diamine.
The amount of the compound represented by the above formula (b-1) is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, and even more preferably 10 to 35 mol% relative to the total diamine component. More preferably, it is 15-30 mol%, even more preferably, it is 15-25 mol%, and even more preferably, it is 20-25 mol%.
The amount of 2,2'-bis (trifluoromethyl) benzidine is preferably 50 to 95 mole%, more preferably 60 to 90 mole%, and even more preferably 65 to 90 moles relative to the total diamine content. Ear%, more preferably 70 to 85 mole%, even more preferably 75 to 85 mole%, and even more preferably 75 to 80 mole%.
The total amount of the compound represented by the above formula (b-1) and 2,2'-bis (trifluoromethyl) benzidine is preferably 70 to 100 mole%, more preferably 85 to the total diamine component. ~ 100 mole%, particularly preferably 99 ~ 100 mole%, and even more preferably 100 mole%.

Furthermore, the diamine component used in the present invention may contain a compound represented by the above formula (b-1) and a diamine component other than 2,2'-bis (trifluoromethyl) benzidine. Examples of the diamine component include at least one selected from the group consisting of an aromatic diamine and an aliphatic diamine. This diamine component can be used individually or in combination of 2 or more types.
In addition, "aromatic diamine" refers to a diamine in which an amine group is directly bonded to an aromatic ring, and a part of the structure may contain an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and other substituents (for example, Halogen atom, sulfonyl group, carbonyl group, oxygen atom, etc.). "Aliphatic diamine" refers to a diamine directly bonded to an amine group and an aliphatic hydrocarbon group or an alicyclic hydrocarbon group. A part of the structure may also contain an aromatic hydrocarbon group, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and other substituents. (For example, a halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.).

Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, benzidine, o-tolylamine, and m-phenylene Toluidine, hexafluorobenzidine, 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-di Amino naphthalene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl Phenylhydrazone, 3,4'-diaminodiphenylhydrazone, 4,4'-diaminobenzophenone, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis [4- (2-methyl-4-aminophenoxy) phenyl] propane, 2,2-bis [4- (2,6-dimethyl-4-aminophenoxy) Phenyl) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (2-methyl-4-aminobenzene (Oxy) 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-aminophenoxy) biphenyl, 4,4'-bis (2,6- Methyl-4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] fluorene, Bis [4- (2-methyl-4-aminophenoxy) phenyl] fluorene, bis [4- (2,6-dimethyl-4-aminophenoxy) phenyl] fluorene, bis [4- (4-Aminophenoxy) phenyl] ether, bis [4- (2-methyl-4-aminophenoxy) phenyl] ether, bis [4- (2,6-di Methyl-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-amino Phenyl) 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-dicumene, α, α'-bis (2-methyl-4-aminophenyl) -1,4-dicumene, α, α'-bis (2,6-bis (Methyl-4-aminophenyl) -1,4-dicumene, α, α'-bis (3-aminophenyl) -1,4-dicumene, α, α'-bis (4-Aminophenyl) -1,3-dicumene, α, α'-bis (2-methyl-4-aminophenyl) -1,3-dicumene, α, α '-Bis (2,6-dimethyl-4-aminophenyl) -1,3-dicumene, α, α'-bis (3-aminophenyl) -1,3-diiso Propylbenzene, 9,9-bis (2-methyl-4-aminophenyl) fluorene, 9,9-bis (2,6-dimethyl-4-aminophenyl) fluorene, 5-amino -1,3,3-trimethyl-1- (4-aminophenyl) -dihydroindene, 1,1-bis (4-aminophenyl) cyclopentane, 1,1-bis (2 -A 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) norbornane, 1,1-bis (2-methyl -4-aminophenyl) norbornane, 1,1-bis (2,6-dimethyl-4-aminophenyl) norbornane, 1,1-bis (4-aminophenyl) Adamantane, 1,1-bis (2-methyl-4-aminophenyl) adamantane, 1,1-bis (2,6-dimethyl-4-aminophenyl) adamantane, and the like. These can be used individually or in combination of 2 or more types.

Examples of the aliphatic diamine include ethylene diamine, hexamethylene diamine, polyethylene glycol bis (3-aminopropyl) ether, and polypropylene glycol bis (3-aminopropyl) ether. , 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, m-xylylenediamine, p-xylylenediamine, 1,4-bis (2-amino-isopropyl) benzene, 1,3-bis (2-amino-isopropyl) benzene, isophoronediamine, norbornanediamine, siloxanediamine, 4, 4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 3,3'-diethyl-4,4'-diamine Dicyclohexylmethane, 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.

The amount of the compound represented by the above formula (b-1) and a diamine component other than 2,2'-bis (trifluoromethyl) benzidine is preferably 30 mol% or less relative to the total diamine component, more preferably It is 15 mol% or less, particularly preferably 1 mol% or less, and even more preferably 0 mol%.

When the polyfluorene imide of the present invention is manufactured, in terms of the amount of the tetracarboxylic acid component added to the diamine component, the diamine component is preferably 0.9 to 1.1 mole relative to 1 mole of the tetracarboxylic acid component.

In the production of the polyfluorene imine of the present invention, in addition to the aforementioned tetracarboxylic acid component and the aforementioned diamine component, an end-capping agent may be used. The capping agent is preferably a monoamine or a dicarboxylic acid. In terms of the amount of the introduced end-capping agent, it is preferably 0.0001 to 0.1 mol, and more preferably 0.001 to 0.06 mol relative to 1 mol of the tetracarboxylic acid component. For monoamine-based capping agents, for example, methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline and the like. Among these, benzylamine and aniline are preferably used. The dicarboxylic acid-type end-capping agent is preferably a dicarboxylic acid, and a part of it may form a ring closure. Examples recommended: Phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone di Carboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, and the like. Among these, phthalic acid and phthalic anhydride can be preferably used.

The method for reacting the tetracarboxylic acid component and the diamine component is not particularly limited, and a known method can be used.
Specific reaction methods include: (1) adding a tetracarboxylic acid component, a diamine component, and a reaction solvent to a reactor, stirring at room temperature to 80 ° C for 0.5 to 30 hours, and then heating and performing方法 A method for imidization reaction; (2) After adding a diamine component and a reaction solvent to the reactor and dissolving them, adding a tetracarboxylic acid component, and stirring at room temperature to 80 ° C for 0.5 to 30 hours as necessary, and thereafter (3) a method of raising the temperature and performing amidine imidization reaction; (3) a method of adding a tetracarboxylic acid component, a diamine component, and a reaction solvent to the reactor, immediately raising the temperature and performing the amidation reaction.

The reaction solvent used in the production of polyimide may be any one that does not interfere with the imidization reaction and that can dissolve the generated polyimide. Examples include aprotic solvents, phenol-based solvents, ether-based solvents, and carbonate-based solvents.

Specific examples of the aprotic solvent include N, N-dimethylisobutylamidine, N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl- Ammonium solvents such as 2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidone, and tetramethylurea; lactone solvents such as γ-butyrolactone and γ-valerolactone ; Phosphamide-containing solvents such as hexamethylphosphamide and hexamethylphosphinetriamine; Sulfur-containing solvents such as dimethylfluorene, dimethylmethylenefluorene, and cyclobutane; Ketone solvents such as methylcyclohexanone; amine solvents such as methylpyridine and pyridine; ester solvents such as acetic acid (2-methoxy-1-methylethyl) and the like.

Specific examples of the phenol-based solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, and 2,6 -Xylenol, 3,4-xylenol, 3,5-xylenol and the like.
Specific examples of the ether-based solvent include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, Bis [2- (2-methoxyethoxy) ethyl] ether, tetrahydrofuran, 1,4-dioxane and the like.
Specific examples of the carbonate-based solvent include diethyl carbonate, methyl ethyl carbonate, ethyl acetate, and propyl carbonate.
Among the above-mentioned reaction solvents, an aprotic solvent is preferable, and a fluorene-based solvent or a lactone-based solvent is more preferable. Moreover, the said reaction solvent can be used individually or in mixture of 2 or more types.

As for the amidine imidization reaction, it is preferable to use a Dean-Stark device or the like to perform the reaction while removing water generated during production. By performing such an operation, the degree of polymerization and the rate of imidization can be further increased.

In the fluorene imidization reaction, a known fluorene imidization catalyst can be used. Examples of the sulfonium imidization catalyst include an alkali catalyst and an acid catalyst.
Examples of the base catalyst include pyridine, quinoline, isoquinoline, α-methylpyridine, β-methylpyridine, 2,4-dimethylpyridine, 2,6-dimethylpyridine, trimethylamine, and triethyl Organic base catalysts such as amine, tripropylamine, tributylamine, imidazole, N, N-dimethylaniline, N, N-diethylaniline; potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, hydrogen carbonate Catalysts for inorganic bases such as potassium and sodium bicarbonate.
Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, and p-toluenesulfonic acid. , Naphthalenesulfonic acid, etc. The said sulfonium imidization catalyst can be used individually or in combination of 2 or more types.
Among the above, from the viewpoint of operability, an alkali catalyst is preferred, an organic alkali catalyst is more preferred, and triethylamine is particularly preferred.

When using the above catalyst, from the viewpoint of the reaction temperature and the inhibition of gelation from the viewpoint of the temperature of the imidization reaction, it is preferably 120 to 250 ° C, more preferably 160 to 190 ° C, and even more preferably 180 to 190. ℃. The reaction time is preferably 0.5 to 10 hours after the start of the distillation of the produced water.
In addition, when the catalyst is not used, the temperature of the imidization reaction is preferably 200 to 350 ° C.
In the reaction between the diamine component and the tetracarboxylic acid component, a polyfluorene imine solution containing at least a polyfluorene imine and a reaction solvent can be obtained after the fluorene imidization reaction is completed.

[Polyimide]
The weight average molecular weight of the polyimide of the present invention is preferably from 500 to 1,000,000, more preferably from 5,000 to 100,000 in view 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.
Examples of the measurement of the weight average molecular weight include a method of measuring the absolute molecular weight using a light scattering detector using N, N-dimethylformamide as a developing solvent.

The polyimide of the present invention may be further mixed with various additives as long as the effect of the present invention is not impaired. Examples of the additives include antioxidants, light stabilizers, surfactants, flame retardants, plasticizers, inorganic fillers, and polymer compounds other than the aforementioned polyimide.
Examples of the polymer compound include polyimide other than the polyimide of the present invention, polycarbonate, polystyrene, polyimide, polyimide, and polyethylene terephthalate. Polyesters such as alcohol esters, polyethers, polycarboxylic acids, polyacetals, polyphenylene ethers, polyfluorenes, polybutenes, polypropylenes, polypropylene amines, polyvinyl chloride, and the like.

[Polyimide varnish]
The polyimide varnish of the present invention is obtained by dissolving the polyimide of the present invention in an organic solvent. That is, the polyimide varnish of the present invention contains the polyimide of the present invention and an organic solvent, and the polyimide is dissolved in the organic solvent.
The organic solvent is not particularly limited as long as it can dissolve polyimide, and the above-mentioned compounds that are reaction solvents used in the production of polyimide are preferably used alone or in combination of two or more.
Since the polyimide of the present invention has solvent solubility, it can be made into a high concentration varnish which is stable at room temperature.

The polyimide varnish may be a polyimide solution itself obtained by dissolving a polyimide obtained by a polymerization method in a reaction solvent. Moreover, the said polyfluorene imine solution may be obtained by mixing at least 1 sort (s) chosen from the solvent exemplified above as the solvent which melt | dissolves the polyfluorene imine.
The solid content concentration of the polyimide varnish of the present invention can be appropriately selected according to workability and the like when forming a polyimide film to be described later, and a reaction solvent used for producing the polyimide of the present invention can also be used. Volatilize and condense, or add an organic solvent as a dilution solvent to adjust the solid content concentration and viscosity of the polyimide varnish of the present invention. The organic solvent is not particularly limited as long as it can dissolve polyimide.
The solid content concentration of the polyimide varnish of the present invention is preferably 5 to 45 mass%, more preferably 5 to 35 mass%, and even more preferably 5 to 25 mass%. The viscosity of the polyimide varnish of the present invention is preferably 0.1 to 200 Pa200s, more preferably 0.5 to 180 Pa ･ s, and even more preferably 1 to 150 Pa ･ s. The viscosity of the polyimide varnish is a value measured at 25 ° C using an E-type viscometer.

[Polyimide film]
The polyimide film of the present invention is characterized by containing the polyimide of the present invention, and maintains high transparency and high heat resistance, and at the same time has a low linear thermal expansion coefficient. The polyimide film of the present invention is preferably composed of the polyimide 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 such as applying a polyimide varnish containing the polyimide of the present invention or a polyimide varnish containing the polyimide of the present invention and the aforementioned various additives to a glass plate or a metal plate may be mentioned. After removing the solvent components such as the reaction solvent and dilution solvent contained in the varnish on a smooth support such as plastic or plastic, or after forming a thin film.
By adjusting the solid content concentration and viscosity of the polyimide varnish in the above manner, the thickness of the polyimide film of the present invention can be easily controlled.

On the surface of the aforementioned support, a release agent may also be applied as needed. The method of coating the said polyimide varnish on the said support body, and heating it to evaporate a solvent component is preferable as follows. That is, it is preferable to evaporate the solvent at a temperature of 120 ° C or lower to make a self-supporting film, then peel the self-supporting film from the support, and fix the ends of the self-supporting film in the solvent used. The component is dried at a temperature above the boiling point of 350 ° C to produce a polyfluoreneimide film. In addition, it is preferable to perform drying under a nitrogen environment. The pressure in the dry environment may be any of reduced pressure, normal pressure, and increased pressure.

The thickness of the polyimide film of the present invention can be appropriately selected according to the application and the like, but it is preferably in the range of 1 to 250 μm, more preferably 5 to 100 μm, even more preferably 7 to 90 μm, and even more preferably 10 to 80 μm. With a thickness of 1 to 250 μm, it can be practically used as a self-supporting film.

In the present invention, the total light transmittance at a thickness of 10 μm is preferably 80% or more, more preferably 85% or more, even more preferably 88% or more, and even more preferably 89% or more polyimide film.
In the present invention, a polyimide film having a yellow index (YI value) of preferably 6.0 or less, more preferably 5.0 or less, and even more preferably 4.5 or less can be formed.
In the present invention, it is possible to form a polyimide film having a haze of preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.5 or less.
In the present invention, a polyimide film having a glass transition temperature of preferably 250 ° C or higher, more preferably 300 ° C or higher, and particularly preferably 350 ° C or higher.

In the present invention, a polyimide film having a linear thermal expansion coefficient of preferably 40 ppm / ° C or lower, more preferably 35 ppm / ° C or lower, and even more preferably 30 ppm / ° C or lower can be formed.
In the present invention, a polyimide film having a tensile elastic modulus (measurement temperature of 23 ° C. and humidity of 50% RH) of preferably 3.0 GPa or more, more preferably 3.5 GPa or more can be formed.
The total light transmittance, YI value, haze, glass transition temperature, linear thermal expansion coefficient, and tensile elastic modulus of the polyimide film can be specifically measured by the methods described in the examples.

The polyimide film containing the polyimide of the present invention is excellent in transparency and heat resistance, has a low coefficient of linear thermal expansion, and therefore has small dimensional change due to heat. It can be ideally used as a color filter and a flexible display. Films for semiconductors, semiconductor parts, and optical components. Since the polyimide film of the present invention has high dimensional stability, it can correspond to a high-temperature step in a manufacturing step of an image display device. Therefore, at least a part of an image display device such as a liquid crystal display or an organic EL display can utilize the polyimide film of the present invention.
[Example]

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples.
The physical properties of the polyimide varnish, polyimide precursor varnish, and polyimide film obtained in the following examples and comparative examples were measured by the methods shown below.

(1) Solid content concentration:
Polyimide varnish or polyimide precursor varnish is used to measure the solid content concentration of the sample using a small electric furnace MMF-1 manufactured by AS ONE Co., Ltd. to heat the sample at 320 ° C for 120 min. The mass difference of the sample is calculated.
(2) Film thickness:
The measurement of the thickness of the polyimide film was performed using a micrometer manufactured by Mitutoyo Co., Ltd.

(3) The tensile elastic modulus is measured in accordance with JIS K7127 using a tensile tester "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. to measure a temperature of 23 ° C, a humidity of 50% RH, a distance between chucks of 50 mm, A tensile test was performed under the condition of a tensile speed of 50 mm / minute, and the tensile elastic modulus was determined.
(4) Glass transition temperature (Tg)
Using a differential scanning calorimeter device "DSC 6200" manufactured by Hitachi High-Tech Science Co., Ltd., a DSC measurement was performed at a temperature rise rate of 10 ° C / min, and the glass transition temperature was determined.

(5) The total light transmittance, yellow index (YI), and haze were measured using a simultaneous color-turbidity measuring device "COH400" manufactured by Nippon Denshoku Industries Co., Ltd. The total light transmittance and YI are measured according to JIS K7361-1: 1997, and the haze is measured according to JIS K7136: 2000.
(6) Coefficient of linear thermal expansion (CTE)
A thermomechanical analysis device (TMA / SS 6100) manufactured by Hitachi High-Tech Science Co., Ltd. was used to perform TMA under the conditions of a sample size of 2 mm × 20 mm, a load of 0.1 N, and a heating rate of 10 ° C./min using a tensile mode It measured and calculated | required CTE of 100-250 degreeC. The closer the CTE value is to 0, the better the dimensional stability.

<Example 1>
In a 5-necked round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen introduction tube, a Dean-Stark device equipped with a cooling tube, a thermometer, and a glass end cap, 2,2'-bis (trifluoromethyl ) Benzidine (manufactured by Wakayama Seika Kogyo Co., Ltd.) 29.462 g (0.092 mol), 9,9-bis (4-aminophenyl) hydrazone (manufactured by Taoka Chemical Industry Co., Ltd.) 8.014 g (0.023 Mol), 111.263 g of N-methyl-2-pyrrolidone (manufactured by Mitsubishi Chemical Co., Ltd.), and the solution was stirred at an internal temperature of 70 ° C and a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.
To this solution, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation) 27.066 g (0.092 mole), 4,4'-(hexafluoroisoprene) were added at one time. Propyl) diphthalic anhydride (made by Daikin Industries, Ltd.) 10.218 g (0.023 mol) and 27.816 g of N-methyl-2-pyrrolidone (made by Mitsubishi Chemical Corporation), and then charged 0.582 g of triethylamine (manufactured by Kanto Chemical Co., Ltd.), which is an imidization catalyst, was heated by a heating mantle, and the temperature inside the reaction system was raised to 190 ° C. in about 20 minutes. The distilled components were collected, and the viscosity was increased to adjust the rotation speed. The temperature in the reaction system was maintained at 190 ° C and refluxed for 1 hour and 30 minutes.
Thereafter, 512.54 g of N-methyl-2-pyrrolidone (manufactured by Mitsubishi Chemical Corporation) was added, and the internal temperature of the reaction system was cooled to 120 ° C, followed by stirring for about 3 hours to homogenize the solid content concentration. 10% by mass solution containing polyimide (polyimide varnish). Then, the obtained polyimide varnish was coated on a glass plate and held at 80 ° C for 30 minutes using a hot plate, and then heated at 300 ° C for 30 minutes in a hot air dryer under a nitrogen purge to evaporate the solvent to obtain Film with a thickness of 10 μm. The results are shown in Table 1.

<Example 2>
In a 5-necked round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen introduction tube, a Dean-Stark device equipped with a cooling tube, a thermometer, and a glass end cap, 2,2'-bis (trifluoromethyl ) Benzidine (manufactured by Wakayama Seika Kogyo Co., Ltd.) 19.685 g (0.061 mole), 9,9-bis (4-aminophenyl) hydrazone (manufactured by Taoka Chemical Industry Co., Ltd.) 5.343 g (0.015 Mol), 75.897 g of N-methyl-2-pyrrolidone (manufactured by Mitsubishi Chemical Co., Ltd.), and the solution was stirred at an internal temperature of 70 ° C. and a nitrogen atmosphere at a rotation speed of 200 rpm.
To this solution, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation) 15.789 g (0.054 mole), 4,4'-(hexafluoroisoprene) were added at once. Propyl) diphthalic anhydride (made by Daikin Industries, Ltd.) 10.218 g (0.023 mole) and N-methyl-2-pyrrolidone (made by Mitsubishi Chemical Corporation) 18.974 g 0.388 g of triethylamine (manufactured by Kanto Chemical Co., Ltd.), which is an imidization catalyst, was heated by a heating mantle, and the temperature inside the reaction system was raised to 190 ° C. in about 20 minutes. The distilled components were collected, and the viscosity was adjusted to increase the rotation speed. The temperature in the reaction system was maintained at 190 ° C and refluxed for 3 hours and 10 minutes.
After that, 349.97 g of N-methyl-2-pyrrolidone (manufactured by Mitsubishi Chemical Corporation) was added, and the internal temperature of the reaction system was cooled to 120 ° C, followed by stirring for about 3 hours to homogenize the solid content concentration. 10% by mass of polyimide varnish. Then, the obtained polyimide varnish was coated on a glass plate and held at 80 ° C for 30 minutes using a hot plate, and then heated at 300 ° C for 30 minutes in a hot air dryer under a nitrogen purge to evaporate the solvent to obtain Film with a thickness of 10 μm. The results are shown in Table 1.

〈Comparative example 1〉
In a 5-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen introduction tube, a Dean-Stark device equipped with a cooling tube, a thermometer, and a glass end cap, put 9,9-bis (4-aminobenzene Base) (24.392g (manufactured by Taoka Chemical Industry Co., Ltd.)) 24.392g (0.070 mole), 66.786g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.), and the internal temperature of the system is 70 ° C under a nitrogen atmosphere. The solution was obtained by stirring at a rotation speed of 200 rpm.
To this solution, 31.097 g (0.070 mol) of 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (manufactured by Daikin Industries, Ltd.) and γ-butyrolactone (Mitsubishi) were added at one time. 16.697 g (manufactured by Chemical Co., Ltd.), and then 0.212 g of triethylamine (manufactured by Kanto Chemical Co., Ltd.) as a sulfonium imidization catalyst was added, and heated by a heating mantle, and the reaction system was allowed to dissolve in about 20 minutes. The temperature rose to 190 ° C. The distilled components were collected and the viscosity was adjusted to increase the rotational speed. The temperature in the reaction system was maintained at 190 ° C and refluxed for 1 hour.
Thereafter, 394.709 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added, and the temperature in the reaction system was cooled to 120 ° C., followed by further stirring for approximately 3 hours to homogenize the solid content to obtain a solid content concentration of 10% by mass. Polyimide varnish. Then, the obtained polyimide varnish was coated on a glass plate and held at 80 ° C. for 20 minutes using a hot plate, and then heated at 400 ° C. for 30 minutes in a hot air dryer under a nitrogen purge to evaporate the solvent to obtain Film with a thickness of 10 μm. The results are shown in Table 1.

〈Comparative example 2〉
In a 5-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen introduction tube, a Dean-Stark device equipped with a cooling tube, a thermometer, and a glass end cap, put 9,9-bis (4-aminobenzene Base) 茀 (manufactured by Taoka Chemical Industry Co., Ltd.) 34.845 g (0.100 mole), N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) 120.202 g, and the internal temperature is 50 Under a nitrogen atmosphere at a temperature of 200C, the solution was stirred at a rotation speed of 200 rpm.
To this solution, 29.420 g (0.100 mole) of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation) and N, N-dimethylacetamide ( 30.050 g of Mitsubishi Gas Chemical Co., Ltd.). After confirming dissolution, return to room temperature, adjust the rotation speed in accordance with the viscosity increase, and continue stirring for 5 hours.
Thereafter, 92.91 g of N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, and the mixture was stirred for about 1 hour to homogenize, thereby obtaining a polyimide precursor having a solid content concentration of 20% by mass ( Polyamic acid) solution (Polyimide precursor varnish). Then, the obtained polyimide precursor varnish was coated on a glass plate and held at 80 ° C. for 20 minutes using a hot plate, and then heated at 400 ° C. for 30 minutes in a hot air dryer under a nitrogen purge to evaporate the solvent. A polyimide film having a thickness of 10 μm was obtained. The results are shown in Table 1.

【Table 1】

The abbreviations in the table are as follows.
s-BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride [compound represented by formula (a-1-1)]
6FDA: 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride [compound represented by formula (a-2)]
BAFL: 9,9-bis (4-aminophenyl) 茀 [Compound represented by formula (b-1) (R: hydrogen atom)]
TFMB: 2,2'-bis (trifluoromethyl) benzidine [compound represented by formula (b-2)]

As can be seen from Table 1, in addition to the high transparency and high heat resistance of the polyimide films of Examples 1 and 2, the linear thermal expansion coefficient is also low. Therefore, all these characteristics are good and balanced. In contrast, the polyimide films of Comparative Examples 1 and 2 had excellent heat resistance, but had a high coefficient of linear thermal expansion, and the transparency of the polyimide films of Comparative Example 2 was also poor. In other words, it is not possible to obtain a film having a low linear thermal expansion coefficient in addition to high transparency and high heat resistance.

Claims (10)

A polyfluorene imine having a constitutional unit A derived from a tetracarboxylic acid or a derivative thereof, and a constitutional unit B derived from a diamine; the constitutional unit A contains a constitutional unit (A- 1), and the structural unit (A-2) derived from the compound represented by the following formula (a-2); the structural unit B contains the structural unit (B-1) derived from the compound represented by the following formula (b-1), and Structural unit (B-2) of the compound represented by the following formula (b-2); [Chemical 2] In formula (b-1), R each independently represents a hydrogen atom, a fluorine atom, or a methyl group. For example, the polyimide of item 1 of the patent application scope, in which the proportion of the constituent unit (A-1) is 50 mol% or more and the proportion of the constituent unit (A-2) is 50 mol relative to the constituent unit A %the following. For example, the polyimide of item 1 or 2 of the patent application scope, wherein the proportion of the constituent unit (B-1) with respect to the constituent unit B is 50 mol% or less, and the proportion of the constituent unit (B-2) is 50 More than%. For example, the polyimide of any of the items 1 to 3 of the scope of application for a patent, wherein the proportion of the total of the constituent unit (A-1) and the constituent unit (A-2) in the constituent unit A is 70 moles. Ear%. For example, the polyimide of any one of the scope of application for patents 1 to 4, wherein the proportion of the total of the constituent unit (B-1) and the constituent unit (B-2) in the constituent unit B is 70 moles. Ear%. For example, the polyimide of any one of claims 1 to 5 of the patent application scope, wherein the proportion of the constituent unit (B-1) with respect to the constituent unit B is 5 mol% or more. For example, the polyimide of any of the items 1 to 6 of the scope of application for a patent, wherein the proportion of the constituent unit (A-1) with respect to the constituent unit A is 60 to 90 mol%, and the constituent unit (A-2 ) Is 10 to 40 mole%. For example, the polyimide of any of the items 1 to 7 of the scope of application for a patent, wherein the ratio of the constituent unit (B-1) to the constituent unit B is 15 to 30 mol%, and the constituent unit (B-2 ) Is 70 to 85 mole%. A polyimide varnish is obtained by dissolving a polyimide in any one of the scope of claims 1 to 8 in an organic solvent. A polyimide film comprising the polyimide according to any one of claims 1 to 8 of the patent application scope.