CN111683992B

CN111683992B - Polyimide resin composition and polyimide film

Info

Publication number: CN111683992B
Application number: CN201980011494.4A
Authority: CN
Inventors: 安孙子洋平; 冈弘明; 末永修也; 高田贵文; 针生智大
Original assignee: Mitsubishi Gas Chemical Co Inc
Current assignee: Mitsubishi Gas Chemical Co Inc
Priority date: 2018-02-05
Filing date: 2019-01-30
Publication date: 2023-05-05
Anticipated expiration: 2039-01-30
Also published as: TW201934617A; WO2019151336A1; TWI799505B; JP7180617B2; CN111683992A; KR20200118027A; KR102663662B1; JPWO2019151336A1

Abstract

The present invention provides a polyimide resin composition and a polyimide film, which can form a film having excellent mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy, and which has excellent storage stability. Disclosed is a polyimide resin composition comprising a polyimide resin and a crosslinking agent having at least 2 oxazolyl groups, wherein the polyimide resin has a constituent unit A and a constituent unit B derived from a diamine, the constituent unit A comprises a constituent unit (A-1), and the constituent unit (A-1) is at least 1 selected from the group consisting of a constituent unit (A-1-1) derived from a compound represented by the formula (a-1-1) and a constituent unit (A-1-2) derived from a compound represented by the formula (a-1-2), and a polyimide film obtained by crosslinking a polyimide resin in the polyimide resin composition with the crosslinking agent; the constituent unit B includes: a constituent unit (B-1) derived from a compound represented by the formula (B-1), and a constituent unit (B-2) derived from a compound represented by the formula (B-2). ( In the formula (b-1), R is independently a hydrogen atom, a fluorine atom or a methyl group; in the formula (b-2), X is a single bond or a specific group, p is an integer of 0 to 2, m1 is an integer of 0 to 4, and m2 is an integer of 0 to 4. Where p is 0, m1 is an integer of 1 to 4. )

Description

Polyimide resin composition and polyimide film

Technical Field

The present invention relates to a polyimide resin composition and a polyimide film.

Background

Polyimide resins have excellent mechanical properties and heat resistance, and thus various applications thereof in the fields of electric/electronic parts and the like are being studied. For example, for the purpose of weight reduction and flexibility of a device, it is desired to replace a glass substrate used in an image display device such as a liquid crystal display or an OLED display with a plastic substrate, and a polyimide film suitable as the plastic substrate is being studied. The polyimide film for such use is required to have colorless transparency.

In addition, a film having poor resistance to an organic solvent such as a polar solvent (resistance to an organic solvent) may have a morphology change due to elution or swelling of its surface when exposed to an organic solvent such as a polar solvent, and thus, polyimide films are often required to have resistance to an organic solvent. In order to meet such a demand, a polyimide film produced by adding a crosslinking agent to a polyimide resin has been proposed.

Patent document 1 discloses a polyimide resin composition containing a polyimide resin having a carboxyl group and a crosslinking agent having at least 2 oxazolyl groups, and describes that a film having good transparency and high hardness can be formed by the polyimide resin composition.

Patent document 2 discloses a transparent flexible film comprising: a polyimide copolymer having a carboxyl group, and a polyfunctional epoxy compound.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication 2016-222797

Patent document 2: japanese patent No. 6174580

Disclosure of Invention

Problems to be solved by the invention

In an image display device, when light emitted from a display element is emitted through a plastic substrate, the plastic substrate is required to have colorless transparency, and when light passes through a retardation film or a polarizing plate (e.g., a liquid crystal display, a touch panel, etc.), the optical isotropy is required to be high in addition to the colorless transparency. However, patent document 1 does not describe any optical isotropy.

In patent document 2, the epoxy group of the polyfunctional epoxy compound added as the crosslinking agent reacts with the carboxyl group even at a relatively low temperature (about 30 ℃ or higher). Therefore, when a composition containing a polyimide resin having a carboxyl group and a polyfunctional epoxy compound is stored at room temperature, gelation due to crosslinking proceeds, and storage stability is poor. In addition, the thermal decomposition temperature of epoxy resins is usually 250 to 350 ℃, and heat resistance is considered insufficient in applications requiring a high temperature process.

The present invention has been made in view of the above circumstances, and an object of the present invention is to: provided are a polyimide resin composition which can form a film excellent in mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy and which is excellent in storage stability, and a polyimide film obtained by crosslinking a polyimide resin in the polyimide resin composition with a crosslinking agent.

Solution for solving the problem

The inventors have found that it comprises: the polyimide resin composition containing a polyimide resin having a specific combination of constituent units and a specific crosslinking agent can solve the above-mentioned problems, and thus has completed the present invention.

That is, the present invention relates to the following [1] to [9].

[1]

A polyimide resin composition comprising: a polyimide resin, and a crosslinking agent having at least 2 oxazolyl groups,

wherein the polyimide resin has a constituent unit A derived from tetracarboxylic dianhydride and a constituent unit B derived from diamine,

the constituent unit A includes a constituent unit (A-1), the constituent unit (A-1) is at least 1 selected from the group consisting of a constituent unit (A-1-1) derived from a compound represented by the following formula (a-1-1) and a constituent unit (A-1-2) derived from a compound represented by the following formula (a-1-2),

The constituent unit B includes: a constituent unit (B-1) derived from a compound represented by the following formula (B-1), and a constituent unit (B-2) derived from a compound represented by the following formula (B-2).

( In the formula (b-1), R is independently a hydrogen atom, a fluorine atom or a methyl group; in the formula (b-2), X is a single bond, a substituted or unsubstituted alkylene group, a carbonyl group, an ether group, a group represented by the following formula (b-2-i), or a group represented by the following formula (b-2-ii), p is an integer of 0 to 2, m1 is an integer of 0 to 4, and m2 is an integer of 0 to 4, wherein when p is 0, m1 is an integer of 1 to 4. )

( In the formula (b-2-i), m3 is an integer of 0 to 5; in the formula (b-2-ii), m4 is an integer of 0 to 5, and m1+m2+m3+m4 is 1 or more, and when p is 2, 2X and 2 m2 to m4 are independently selected. )

[2]

The polyimide resin composition according to the above [1], wherein the constituent unit (B-2) is a constituent unit (B-21) derived from a compound represented by the following formula (B-21).

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[3]

The polyimide resin composition according to the above [1] or [2], wherein the crosslinking agent contains a benzene ring to which the above-mentioned at least 2 oxazolyl groups are bonded.

[4]

The polyimide resin composition according to any one of the above [1] to [3], which contains the polyimide resin and the crosslinking agent in a ratio such that a molar ratio of the oxazolyl group in the crosslinking agent to the carboxyl group in the polyimide resin (oxazolyl/carboxyl group) is in a range of 1/4 to 1/0.5.

[5]

The polyimide resin composition according to any one of the above [1] to [4], wherein the ratio of the constituent unit (B-1) in the constituent unit B is 40 to 99 mol%,

the proportion of the constituent unit (B-2) in the constituent unit B is 1 to 60 mol%.

[6]

The polyimide resin composition according to any one of the above [1] to [5], wherein the ratio of the constituent unit (A-1) in the constituent unit A is 50 mol% or more.

[7]

The polyimide resin composition according to any one of the above [1] to [6], wherein the constituent unit (A-1) is the constituent unit (A-1-1).

[8]

The polyimide resin composition according to any one of the above [1] to [6], wherein the constituent unit (A-1) is the constituent unit (A-1-2).

[9]

A polyimide film obtained by crosslinking the polyimide resin in the polyimide resin composition according to any one of the above [1] to [8] with the crosslinking agent.

ADVANTAGEOUS EFFECTS OF INVENTION

The polyimide resin composition of the present invention has excellent storage stability, and can be formed into a film having excellent mechanical properties, resistance to organic solvents, colorless transparency, and optical isotropy.

Detailed Description

[ polyimide resin composition ]

The polyimide resin composition of the present invention comprises a polyimide resin and a crosslinking agent. Hereinafter, the polyimide resin and the crosslinking agent in the present invention will be described.

< polyimide resin >

In the present invention, a polyimide resin has a constituent unit A derived from a tetracarboxylic dianhydride and a constituent unit B derived from a diamine, wherein the constituent unit A contains a constituent unit (A-1), the constituent unit (A-1) is at least 1 selected from the group consisting of a constituent unit (A-1-1) derived from a compound represented by the following formula (a-1-1) and a constituent unit (A-1-2) derived from a compound represented by the following formula (a-1-2), and the constituent unit B contains: a constituent unit (B-1) derived from a compound represented by the following formula (B-1), and a constituent unit (B-2) derived from a compound represented by the following formula (B-2).

(constituent Unit A)

The constituent unit A is a constituent unit derived from tetracarboxylic dianhydride in a polyimide resin, and comprises a constituent unit (A-1), wherein the constituent unit (A-1) is at least 1 selected from the group consisting of a constituent unit (A-1-1) derived from a compound represented by the following formula (a-1-1) and a constituent unit (A-1-2) derived from a compound represented by the following formula (a-1-2).

The compound represented by the formula (a-1-1) is 1,2,4, 5-cyclohexane tetracarboxylic dianhydride.

The compound shown in the formula (a-1-2) is norbornane-2-spiro-alpha-cyclopentanone-alpha '-spiro-2' -norbornane-5, 5 ', 6' -tetracarboxylic dianhydride.

The inclusion of the constituent unit (A-1) in the constituent unit A contributes to the improvement of the colorless transparency of the film. In addition, when the constituent unit (A-1) is included as the constituent unit (A-1-1), the optical isotropy of the film can be improved.

The constituent unit (A-1) may be only the constituent unit (A-1-1), or may be only the constituent unit (A-1-2). The constituent unit (A-1) may be a combination of the constituent unit (A-1-1) and the constituent unit (A-1-2).

The ratio of the constituent unit (a-1) in the constituent unit a is preferably 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the ratio of the constituent unit (A-1) is not particularly limited, and is 100 mol%. The constituent unit A may contain only the constituent unit (A-1).

The constituent unit A may contain constituent units other than the constituent unit (A-1). The tetracarboxylic dianhydride providing such a constituent unit is not particularly limited, and examples thereof include pyromellitic dianhydride, 3',4' -biphenyl tetracarboxylic dianhydride, 2, 3',4' -biphenyl tetracarboxylic dianhydride, 2',3,3' -biphenyltetracarboxylic dianhydride, 9' -bis (3, 4-dicarboxyphenyl) fluorene dianhydride, 4' - (hexafluoroisopropylidene) dicarboxylic anhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 3',4,4' -diphenyl sulfone tetracarboxylic dianhydride, 4' -oxydiphthalic anhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 2', aromatic tetracarboxylic dianhydrides such as 3,3' -benzophenone tetracarboxylic dianhydride, 4- (p-phenylene dioxy) dicarboxylic dianhydride, and 4,4- (m-phenylene dioxy) dicarboxylic dianhydride; alicyclic tetracarboxylic dianhydrides such as 1,2,3, 4-cyclobutanetetracarboxylic dianhydride (excluding the compound represented by the formula (a-1-1) and the compound represented by the formula (a-1-2)); aliphatic tetracarboxylic dianhydrides such as 1,2,3, 4-butanetetracarboxylic dianhydride.

In the present specification, the aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing 1 or more aromatic rings, the alicyclic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing 1 or more alicyclic rings and not containing an aromatic ring, and the aliphatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.

The constituent units (A) may be 1 or 2 constituent units other than the constituent unit (A-1).

As a preferable embodiment of the constituent unit other than the constituent unit (A-1), a constituent unit (A-2) derived from a compound represented by the following formula (a-2) is given.

The compound represented by the formula (a-2) is diphenyl tetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3',4' -diphenyl tetracarboxylic dianhydride (s-BPDA) represented by the following formula (a-2 s), 2, 3',4' -diphenyl tetracarboxylic dianhydride (a-BPDA) represented by the following formula (a-2 a), and 2,2', 3' -diphenyl tetracarboxylic dianhydride (i-BPDA) represented by the following formula (a-2 i).

When the constituent unit A includes the constituent unit (A-1) and the constituent unit (A-2), the ratio of the constituent unit (A-1) in the constituent unit A is preferably 50 to 95 mol%, more preferably 70 to 95 mol%, still more preferably 85 to 95 mol%, and the ratio of the constituent unit (A-2) in the constituent unit A is preferably 5 to 50 mol%, more preferably 5 to 30 mol%, still more preferably 5 to 15 mol%.

The constituent unit A may include only the constituent unit (A-1) and the constituent unit (A-2).

(constituent Unit B)

The constituent unit B is a diamine-derived constituent unit in a polyimide resin, and includes: a constituent unit (B-1) derived from a compound represented by the following formula (B-1), and a constituent unit (B-2) derived from a compound represented by the following formula (B-2).

( In the formula (b-1), R is independently a hydrogen atom, a fluorine atom or a methyl group; in the formula (b-2), X is a single bond, a substituted or unsubstituted alkylene group, a carbonyl group, an ether group, a group represented by the following formula (b-2-i), or a group represented by the following formula (b-2-ii), p is an integer of 0 to 2, m1 is an integer of 0 to 4, and m2 is an integer of 0 to 4. Where p is 0, m1 is an integer of 1 to 4. )

( In the formula (b-2-i), m3 is an integer of 0 to 5; in the formula (b-2-ii), m4 is an integer of 0 to 5. When m1+m2+m3+m4 is 1 or more and p is 2, 2X and 2 m2 to m4 are independently selected. )

In the formula (b-1), R is each independently a hydrogen atom, a fluorine atom, or a methyl group, preferably a hydrogen atom. Examples of the compound represented by the formula (b-1) include 9, 9-bis (4-aminophenyl) fluorene, 9-bis (3-fluoro-4-aminophenyl) fluorene, 9-bis (3-methyl-4-aminophenyl) fluorene, and the like, and 9, 9-bis (4-aminophenyl) fluorene is preferable.

By including the constituent unit (B-1) in the constituent unit B, the optical isotropy of the film is improved.

Specific examples of the compound represented by the formula (b-2) include compounds represented by the following formulas (b-21) to (b-27).

Among the above-mentioned compounds, the compound represented by the formula (b-21) is preferable, and the compound represented by the following formula (b-211), namely, 3, 5-diaminobenzoic acid, is more preferable.

The constituent unit (B-2) is a constituent unit that gives a carboxyl group to the polyimide resin. The polyimide resin has carboxyl groups, and thus crosslinking between polyimide resins by a crosslinking agent described later becomes possible. Therefore, by including the constituent unit (B-2) in the constituent unit B, the organic solvent resistance of the film is improved.

The proportion of the constituent unit (B-1) in the constituent unit B is preferably 40 to 99 mol%, more preferably 45 to 95 mol%, still more preferably 75 to 95 mol%, particularly preferably 80 to 90 mol%.

The ratio of the constituent unit (B-2) in the constituent unit B is preferably 1 to 60 mol%, more preferably 5 to 55 mol%, still more preferably 5 to 25 mol%, particularly preferably 10 to 20 mol%.

The total ratio of the constituent units (B-1) and (B-2) in the constituent unit B is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the total ratio of the constituent unit (B-1) and the constituent unit (B-2) is not particularly limited, and is 100 mol%. The constituent unit B may include only the constituent unit (B-1) and the constituent unit (B-2).

The constituent unit B may include constituent units other than the constituent units (B-1) and (B-2). The diamine providing such a constituent unit is not particularly limited, examples thereof include 1, 4-phenylenediamine, p-xylylenediamine, 2 '-dimethylbiphenyl-4, 4' -diamine, 2 '-bis (trifluoromethyl) benzidine, 4' -diaminodiphenyl ether, 4 '-diamino-2, 2' -bistrifluoromethyl diphenyl ether 4,4 '-diaminodiphenylmethane, 2-bis (4-aminophenyl) hexafluoropropane, bis (4-aminophenyl) sulphone, 4' -diaminoanilide, 1- (4-aminophenyl) -2, 3-dihydro-1, 3-trimethyl-1H-inden-5-amine, alpha, alpha '-bis (4-aminophenyl) -1, 4-diisopropylbenzene, N, N' -bis (4-aminophenyl) terephthalamide, 4 '-bis (4-aminophenoxy) biphenyl, 2-bis [ 4- (4-aminophenoxy) phenyl ] propane, 2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane aromatic diamines such as 5,5' - (1, 3-hexafluoro-2-hydroxyisopropyl) -2,2 '-dimethylbiphenyl-4, 4' -diamine and 9, 9-bis (4- (4-aminophenoxy) phenyl) fluorene (among them, except for the compound represented by the formula (b-1) and the compound represented by the formula (b-2); alicyclic diamines such as 1, 3-bis (aminomethyl) cyclohexane and 1, 4-bis (aminomethyl) cyclohexane; aliphatic diamines such as ethylenediamine and hexamethylenediamine.

In the present specification, an aromatic diamine means a diamine containing 1 or more aromatic rings, an alicyclic diamine means a diamine containing 1 or more alicyclic rings and no aromatic rings, and an aliphatic diamine means a diamine containing neither aromatic rings nor alicyclic rings.

The constituent units (B) may be 1 or 2 or more constituent units other than the constituent units (B-1) and (B-2).

In the present invention, the number average molecular weight of the polyimide resin is preferably 5000 to 100000 from the viewpoint of the mechanical strength of the obtained polyimide film. The number average molecular weight of the polyimide resin can be determined, for example, based on a standard polymethyl methacrylate (PMMA) conversion measured by gel filtration chromatography.

< method for producing polyimide resin >

In the present invention, a polyimide resin can be produced by reacting a tetracarboxylic acid component containing a compound providing the above-mentioned constituent unit (a-1) with a diamine component comprising: the compound providing the above-mentioned constituent unit (B-1) and the compound providing the above-mentioned constituent unit (B-2).

As the compound providing the constituent unit (A-1), at least 1 selected from the group consisting of a compound providing the constituent unit (A-1-1) and a compound providing the constituent unit (A-1-2) is used.

The compound providing the constituent unit (A-1-1) is exemplified by a compound represented by the formula (a-1-1), but is not limited thereto, and may be a derivative thereof in a range where the same constituent unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-1-1) (i.e., 1,2,4, 5-cyclohexane tetracarboxylic acid), and an alkyl ester of the tetracarboxylic acid. As the compound which provides the constituent unit (A-1-1), a compound represented by the formula (a-1-1) (i.e., dianhydride) is preferable.

The compound providing the constituent unit (A-1-2) is exemplified by the compound represented by the formula (a-1-2), but is not limited thereto, and may be a derivative thereof in a range where the same constituent unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-1-2), and an alkyl ester of the tetracarboxylic acid. As the compound providing the constituent unit (A-1-2), a compound represented by the formula (a-1-2) (i.e., dianhydride) is preferable.

As the compound providing the constituent unit (A-1), only the compound providing the constituent unit (A-1-1) may be used, or only the compound providing the constituent unit (A-1-2) may be used.

In addition, as the compound providing the constituent unit (A-1), a combination of a compound providing the constituent unit (A-1-1) and a compound providing the constituent unit (A-1-2) may be used.

The tetracarboxylic acid component preferably contains 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol% or more of the compound providing the constituent unit (a-1). The upper limit of the content of the compound providing the constituent unit (A-1) is not particularly limited, and is 100 mol%. The tetracarboxylic acid component may contain only the compound providing the constituent unit (A-1).

The tetracarboxylic acid component may contain compounds other than the compound providing the constituent unit (a-1), and examples of the compound include the above-mentioned aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aliphatic tetracarboxylic dianhydride, and derivatives thereof (tetracarboxylic acid, alkyl esters of tetracarboxylic acid, and the like).

The number of compounds other than the compound providing the constituent unit (A-1) optionally contained in the tetracarboxylic acid component may be 1 or 2 or more.

As a preferable embodiment of the compound other than the compound providing the constituent unit (A-1), there is a compound providing the constituent unit (A-2).

The compound providing the constituent unit (A-2) is exemplified by the compound represented by the formula (a-2), but is not limited thereto, and may be a derivative thereof in a range where the same constituent unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-2), and an alkyl ester of the tetracarboxylic acid. As the compound which provides the constituent unit (A-2), a compound represented by the formula (a-2) (i.e., dianhydride) is preferable.

When the tetracarboxylic acid component contains the compound for providing the constituent unit (A-1) and the compound for providing the constituent unit (A-2), the tetracarboxylic acid component preferably contains 50 to 95 mol%, more preferably 70 to 95 mol%, still more preferably 85 to 95 mol%, of the compound for providing the constituent unit (A-1), preferably 5 to 50 mol%, more preferably 5 to 30 mol%, still more preferably 5 to 15 mol%, of the compound for providing the constituent unit (A-2).

The tetracarboxylic acid component may contain only the compound providing the constituent unit (A-1) and the compound providing the constituent unit (A-2).

The compound providing the constituent unit (B-1) is exemplified by a compound represented by the formula (B-1), but is not limited thereto, and may be a derivative thereof in a range where the same constituent unit is provided. The derivative may be a diisocyanate corresponding to the diamine represented by the formula (b-1). As the compound providing the constituent unit (B-1), a compound represented by the formula (B-1) (i.e., diamine) is preferable.

The compound providing the constituent unit (B-2) is exemplified by the compound represented by the formula (B-2), but is not limited thereto, and may be a derivative thereof in a range where the same constituent unit is provided. The derivative may be a diisocyanate corresponding to the diamine represented by the formula (b-2). As the compound providing the constituent unit (B-2), a compound represented by the formula (B-2) (i.e., diamine) is preferable.

The diamine component preferably contains 40 to 99 mol%, more preferably 45 to 95 mol%, still more preferably 75 to 95 mol%, and particularly preferably 80 to 90 mol% of the compound providing the constituent unit (B-1).

The diamine component preferably contains 1 to 60 mol%, more preferably 5 to 55 mol%, still more preferably 5 to 25 mol%, particularly preferably 10 to 20 mol% of the compound providing the constituent unit (B-2).

The diamine component contains the compound providing the constituent unit (B-1) and the compound providing the constituent unit (B-2) in total, preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the total content of the compound providing the constituent unit (B-1) and the compound providing the constituent unit (B-2) is not particularly limited, that is, 100 mol%. The diamine component may contain only the compound providing the constituent unit (B-1) and the compound providing the constituent unit (B-2).

The diamine component may contain a compound other than the compound providing the constituent unit (B-1) and the compound providing the constituent unit (B-2), and examples of the compound include the above aromatic diamine, alicyclic diamine, aliphatic diamine, and derivatives thereof (diisocyanate, etc.).

The number of compounds other than the compound providing the constituent unit (B-1) and the compound providing the constituent unit (B-2) optionally contained in the diamine component may be 1 or 2 or more.

In the present invention, the ratio of the amount of the tetracarboxylic acid component to the amount of the diamine component to be added for the production of the polyimide resin is preferably 0.9 to 1.1 mol based on 1 mol of the tetracarboxylic acid component.

In the present invention, in addition to the tetracarboxylic acid component and the diamine component, a capping agent may be used in the production of the polyimide resin. As the blocking agent, monoamines or dicarboxylic acids are preferable. The amount of the blocking agent to be introduced is preferably 0.0001 to 0.1 mol, particularly preferably 0.001 to 0.06 mol, based on 1 mol of the tetracarboxylic acid component. As monoamine-type blocking 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 are recommended. Among these, benzylamine and aniline can be suitably used. The dicarboxylic acid-based capping agent is preferably a dicarboxylic acid, and a part of the dicarboxylic acid-based capping agent may be closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2, 3-benzophenone dicarboxylic acid, 3, 4-benzophenone dicarboxylic acid, cyclohexane-1, 2-dicarboxylic acid, cyclopentane-1, 2-dicarboxylic acid, 4-cyclohexene-1, 2-dicarboxylic acid, and the like are recommended. Among these, phthalic acid and phthalic anhydride can be suitably 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 the following: (1) a method in which the tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into a reactor and stirred at room temperature to 80 ℃ for 0.5 to 30 hours, and then the reaction mixture is warmed up to carry out imidization, (2) a method in which the diamine component and the reaction solvent are added into a reactor and dissolved, and then the tetracarboxylic acid component is charged into the reactor and stirred at room temperature to 80 ℃ for 0.5 to 30 hours, and then the reaction mixture is warmed up to carry out imidization, and (3) a method in which the tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into a reactor and immediately warmed up to carry out imidization, and the like.

The reaction solvent used for producing the polyimide resin may be one which does not inhibit imidization and which can dissolve the polyimide resin produced. Examples thereof include aprotic solvents, phenolic solvents, ether solvents, and carbonate solvents.

Specific examples of the aprotic solvent include amide solvents such as N, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1, 3-dimethylimidazolidinone, tetramethylurea, lactone solvents such as γ -butyrolactone and γ -valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphoric triamide, sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide and sulfolane, ketone solvents such as acetone, cyclohexanone and methylcyclohexanone, amine solvents such as picoline and pyridine, and ester solvents such as (2-methoxy-1-methylethyl) acetate.

Specific examples of the phenol-based solvent include phenol, o-cresol, m-cresol, p-cresol, 2, 3-xylenol, 2, 4-xylenol, 2, 5-xylenol, 2, 6-xylenol, 3, 4-xylenol, and 3, 5-xylenol.

Specific examples of the ether solvent include 1, 2-dimethoxyethane, bis (2-methoxyethyl) ether, 1, 2-bis (2-methoxyethoxy) ethane, bis [ 2- (2-methoxyethoxy) ethyl ] ether, tetrahydrofuran, and 1, 4-dioxane.

Specific examples of the carbonate-based solvent include diethyl carbonate, methylethyl carbonate, ethylene carbonate, propylene carbonate, and the like.

Among the above reaction solvents, an amide-based solvent or a lactone-based solvent is preferable. The reaction solvent may be used alone or in combination of two or more.

In the imidization reaction, it is preferable to use a dean-stark apparatus or the like, and to perform the reaction while removing the water produced at the time of production. By performing such an operation, the polymerization degree and the imidization rate can be further increased.

In the imidization reaction, a known imidization catalyst may be used. Examples of the imidization catalyst include a base catalyst and an acid catalyst.

Examples of the base catalyst include organic base catalysts such as pyridine, quinoline, isoquinoline, α -picoline, β -picoline, 2, 4-lutidine, 2, 6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N-dimethylaniline, N-diethylaniline, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate.

Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexanoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, and the like. The imidization catalyst may be used singly or in combination of two or more.

From the viewpoint of handling properties, among the above, a base catalyst is preferably used, an organic base catalyst is more preferably used, triethylamine is more preferably used, and triethylamine and triethylenediamine are particularly preferably used in combination.

The temperature of the imidization reaction is preferably 120 to 250 ℃, more preferably 160 to 200 ℃, from the viewpoints of the reaction rate, gelation, and the like. The reaction time is preferably 0.5 to 10 hours after the start of distillation of the produced water.

< crosslinking agent >

In the present invention, the crosslinker has at least 2 oxazolyl groups. That is, the crosslinking agent in the present invention is a polyfunctional oxazoline compound having 2 or more oxazolyl groups (oxazoline rings) in the molecule.

The oxazolyl group has reactivity with a carboxyl group, and when the carboxyl group reacts with the oxazolyl group, an amide ester bond shown below is formed. The reaction is particularly easy to carry out when heated above 80 ℃.

Since the polyimide resin contained in the polyimide resin composition of the present invention has carboxyl groups, the polyimide resins are crosslinked with each other by the crosslinking agent when the polyimide resin composition of the present invention is heated, thereby forming a crosslinked polyimide resin. For this reason, the organic solvent resistance of the film is improved. In addition, since the reaction between the oxazolyl group and the carboxyl group hardly proceeds at room temperature, the polyimide resin composition of the present invention is excellent in storage stability.

The crosslinking agent is not particularly limited as long as it is a compound having 2 or more oxazolyl groups in the molecule, and specific examples thereof include 1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene, 1, 4-bis (4, 5-dihydro-2-oxazolyl) benzene, 2' -bis (2-oxazoline), K-2010E, K-2020E, K-2030E manufactured by japan catalyst, 2, 6-bis (4-isopropyl-2-oxazolin-2-yl) pyridine, 2, 6-bis (4-phenyl-2-oxazolin-2-yl) pyridine, 2' -isopropylidenebis (4-phenyl-2-oxazoline), 2' -isopropylidenebis (4-tert-butyl-2-oxazoline), and the like.

The crosslinking agent is preferably a compound containing an aromatic ring or an aromatic heterocyclic ring to which at least 2 oxazolyl groups are bonded, more preferably a compound containing a benzene ring to which at least 2 oxazolyl groups are bonded, and still more preferably 1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene.

The crosslinking agent may be used alone or in combination of two or more.

The polyimide resin composition of the present invention is preferably: the polyimide resin and the crosslinking agent are contained in such a ratio that the molar ratio of the oxazolyl group in the crosslinking agent to the carboxyl group in the polyimide resin (oxazolyl/carboxyl group) is in the range of 1/4 to 1/0.5. The molar ratio is more preferably 1/4 to 1/1, and still more preferably 1/2 to 1/1.

The molar ratio mentioned above means: the molar ratio of the oxazolyl group contained in the crosslinking agent to the carboxyl group contained in the compound providing the constituent unit (B-2) used in the production of the polyimide resin is calculated based on the amount of the crosslinking agent added and the amount of the compound providing the constituent unit (B-2) added.

As a preferred embodiment of the polyimide resin composition of the present invention, an organic solvent is contained in addition to the polyimide resin and the crosslinking agent, and a polyimide resin composition (hereinafter also referred to as "polyimide varnish") in which the polyimide resin is dissolved in the organic solvent is exemplified.

The organic solvent is not particularly limited as long as the polyimide resin is dissolved, and the compounds described above as the reaction solvents used for producing the polyimide resin are preferably used singly or in combination of 2 or more.

The polyimide varnish may be obtained by adding a crosslinking agent to a solution obtained by dissolving a polyimide resin obtained by a polymerization method in a reaction solvent, or may be obtained by adding a diluting solvent and a crosslinking agent to the solution.

The polyimide resin described above has solvent solubility and undergoes little crosslinking reaction with a crosslinking agent at room temperature. Therefore, a polyimide varnish of high concentration stable at room temperature can be obtained. The polyimide varnish preferably contains 5 to 40 mass% of the polyimide resin, more preferably 10 to 30 mass%. The viscosity of the polyimide varnish is preferably 1 to 200pa·s, more preferably 5 to 150pa·s. The viscosity of the polyimide varnish was determined at 25℃using an E-type viscometer.

The polyimide resin composition of the present invention may contain various additives such as an inorganic filler, an adhesion promoter, a release agent, a flame retardant, an ultraviolet stabilizer, a surfactant, a leveling agent, an antifoaming agent, a fluorescent whitening agent, a crosslinking agent, a polymerization initiator, and a photosensitizer, within a range that does not impair the desired properties of the polyimide film.

The method for producing the polyimide resin composition of the present invention is not particularly limited, and a known method can be applied.

The polyimide resin composition of the present invention can form a film excellent in mechanical properties, resistance to organic solvents, colorless transparency, and optical isotropy. Preferred physical properties of the film which can be formed using the polyimide resin composition of the present invention are as follows.

The tensile strength is preferably 50MPa or more, more preferably 60MPa or more, and still more preferably 70MPa or more.

The tensile elastic modulus is preferably 2.0GPa or more, more preferably 2.2GPa or more, and still more preferably 2.5GPa or more.

The total light transmittance is preferably 87% or more, more preferably 88% or more, and even more preferably 89% or more, when a film having a thickness of 10 μm is formed.

The Yellowness Index (YI) is preferably 6.8 or less, more preferably 3.5 or less, and even more preferably 2.2 or less when a film having a thickness of 10 μm is produced.

The absolute value of the thickness retardation (Rth) is preferably 75nm or less, more preferably 25nm or less, and even more preferably 10nm or less when a film having a thickness of 10 μm is produced.

In the present invention, the tensile strength, tensile elastic modulus, total light transmittance, yellowness Index (YI), and thickness retardation (Rth) are specifically measured by the methods described in examples.

[ polyimide film ]

The polyimide film of the present invention is obtained by crosslinking the polyimide resin contained in the polyimide resin composition of the present invention with the crosslinking agent. That is, the polyimide film of the present invention contains a crosslinked polyimide resin, which is a crosslinked product of polyimide resins with a crosslinking agent interposed therebetween. Therefore, the polyimide film of the present invention is excellent in mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy. The polyimide film of the present invention has preferable physical properties as described above.

The method for producing a polyimide film of the present invention is not particularly limited as long as it includes a step of crosslinking at a temperature at which the crosslinking reaction between the polyimide resin and the crosslinking agent proceeds (preferably 80 ℃ or higher, more preferably 100 ℃ or higher, and still more preferably 150 ℃ or higher). Examples thereof include: the polyimide varnish is coated on a smooth support such as a glass plate, a metal plate, or a plastic, or formed into a film and then heated. By this heat treatment, the organic solvent such as the reaction solvent and the diluting solvent contained in the polyimide varnish can be removed while the crosslinking reaction between the polyimide resin and the crosslinking agent in the polyimide varnish proceeds. If necessary, the surface of the support may be coated with a release agent in advance.

As a method of applying the polyimide varnish to the support, known application methods such as spin coating, slit coating, and doctor blade coating are mentioned.

The following method is preferable as the heat treatment. Namely, it is preferable that: after the organic solvent is evaporated at a temperature of 60 to 150 ℃ to prepare a self-supporting film, the self-supporting film is peeled off from the support, and the end of the self-supporting film is fixed and dried at a temperature equal to or higher than the boiling point of the organic solvent used to prepare a polyimide film. In addition, the drying is preferably performed under a nitrogen atmosphere. The pressure of the drying atmosphere may be reduced, normal pressure or increased. The heating temperature in the case of drying the self-supporting film to produce a polyimide film is not particularly limited, but is preferably 250 to 400 ℃.

The thickness of the polyimide film of the present invention may be appropriately selected depending on the application, etc., and is preferably in the range of 1 to 250. Mu.m, more preferably 5 to 100. Mu.m, and still more preferably 10 to 80. Mu.m. The thickness of the film is 1 to 250. Mu.m, so that the film can be practically used as a self-supporting film.

The thickness of the polyimide film can be easily controlled by adjusting the solid concentration and viscosity of the polyimide varnish.

The polyimide film of the present invention can be suitably used as a film for various members such as color filters, flexible displays, semiconductor parts, optical members, and the like. The polyimide film of the present invention is particularly suitable for use as a substrate for image display devices such as liquid crystal displays and OLED displays.

Examples

The present invention will be specifically described below by way of examples. However, the present invention is not limited to these examples.

The solid content concentrations of the polyimide resin solutions and polyimide varnishes obtained in the examples and comparative examples and the respective physical properties of the polyimide films were measured by the methods shown below.

(1) Concentration of solid content

For the measurement of the solid content concentration of the polyimide resin solution and polyimide varnish, the sample was heated at 320℃for 120 minutes by a small electric furnace "MMF-1" made of AS ONE CORPORATION, and the mass difference of the sample before and after the heating was calculated.

(2) Film thickness

Film thickness was measured using a micrometer manufactured by Sanfeng corporation.

(3) Tensile Strength, tensile elastic modulus

The measurement was carried out in accordance with JIS K7127 using the tensile tester "Stroggraph VG-1E" manufactured by Toyo Seisakusho Co.

(4) Total light transmittance, yellowness Index (YI)

The measurement was carried out in accordance with JIS K7361-1 using a color/turbidity simultaneous measuring instrument "COH400" manufactured by Nippon Denshoku Kogyo Co.

(5) Thickness retardation (Rth)

The thickness retardation (Rth) was measured by using ellipsometer "M-220" manufactured by Nippon spectroscopic Co. The thickness phase difference value at the measurement wavelength of 590nm was measured. Note that Rth is expressed by the following formula, where nx is the maximum value and ny is the minimum value of refractive indexes in the surface of the polyimide film, nz is the refractive index in the thickness direction, and d is the thickness of the film.

Rth＝[{(nx+ny)/2}-nz]×d

(6) Resistance to organic solvents

The obtained film was immersed in an organic solvent at 60℃for 3 hours, and the organic solvent resistance was evaluated. As the organic solvent, N-methyl-2-pyrrolidone (NMP) was used.

The evaluation criteria for the resistance to organic solvents were set as follows.

B: the film surface was dissolved after being immersed in an organic solvent for less than 3 hours.

A: even after 3 hours of impregnation with the organic solvent, the film surface was not dissolved and did not change.

The tetracarboxylic acid component, diamine component, crosslinking agent, and abbreviations thereof used in examples and comparative examples are as follows.

< tetracarboxylic acid component >

HPMDA:1,2,4, 5-cyclohexane tetracarboxylic dianhydride (Mitsubishi gas chemical Co., ltd.; compound represented by formula (a-1-1))

CpODA: norbornane-2-spiro- α -cyclopentanone- α' -spiro-2 "-norbornane-5, 5",6 "-tetracarboxylic dianhydride (JX 2 x one co; compounds of formula (a-1-2)

s-BPDA:3,3', 4' -Biphenyltetracarboxylic dianhydride (Mitsubishi chemical Co., ltd.; compound represented by formula (a-2 s))

< diamine component >

BAFL:9, 9-bis (4-aminophenyl) fluorene (a compound represented by formula (b-1) manufactured by Tiangang chemical industry Co., ltd.)

3,5-DABA:3, 5-diaminobenzoic acid (Compound represented by formula (b-211) of Japanese pure Liang Yak Co., ltd.)

mTB:2,2 '-dimethylbiphenyl-4, 4' -diamine (available from Sema Co., ltd.)

< crosslinking agent >

1,3-PBO:1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene (MIKUNI PHARMACEUTICAL INDUSTRIAL co., ltd.)

TG: triglycidyl isocyanurate (Tokyo chemical industry Co., ltd.)

< example 1A >

BAFL 27.876g (0.080 mol), 3,5-DABA 3.043g (0.020 mol) and gamma-butyrolactone (Mitsubishi chemical Co., ltd.) 79.242g were charged into a 1L 5-neck round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a dean-Stark apparatus equipped with a condenser tube, a thermometer, and a glass end cap, and stirred at a temperature of 70℃in the system under a nitrogen atmosphere and a rotation speed of 200rpm, to obtain a solution.

To this solution, 22.417g (0.100 mol) of HPDA and 19.811g of gamma-butyrolactone (Mitsubishi chemical Co., ltd.) were added at a time, and then 0.506g of triethylamine (Kanto chemical Co., ltd.) as an imidization catalyst was added, and the mixture was heated by a hood heater to raise the temperature in the reaction system to 190℃over about 20 minutes. The distilled-off components were collected, the rotation speed was adjusted according to the increase in viscosity, and the temperature in the reaction system was kept at 190℃for 3 hours for reflux.

Then, 351.779g of γ -butyrolactone (mitsubishi chemical Co., ltd.) was added, and the reaction system was cooled to 120℃and stirred for about 3 hours to homogenize the mixture, thereby obtaining a polyimide resin solution (1) having a solid content of 10.0% by mass.

Next, 0.216g (0.001 mol) of 1,3-PBO as a crosslinking agent was added to 100g of the polyimide resin solution (1), and the mixture was stirred at room temperature for 1 hour to obtain a polyimide varnish containing the crosslinking agent and the polyimide resin in a solid content concentration of 10.2 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/2.

Then, the polyimide varnish obtained was applied to a glass plate, and the resultant was kept at 80℃for 20 minutes by a hot plate, and then heated in a hot air dryer at 350℃for 30 minutes under a nitrogen atmosphere to evaporate the solvent, thereby obtaining a film having a thickness of 18. Mu.m. The results are shown in Table 1.

< example 1B >

A polyimide varnish was produced in the same manner as in example 1A except that the amount of the crosslinking agent 1,3-PBO added to the polyimide resin solution (1) was changed to 0.432g (0.002 mol), and a polyimide varnish containing the crosslinking agent and the polyimide resin in a solid content concentration of 10.4 mass% was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/1.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 1A, to obtain a film having a thickness of 17 μm. The results are shown in Table 1.

Comparative example 1 ]

A polyimide varnish was produced in the same manner as in example 1A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (1). That is, the polyimide resin solution (1) was directly used as a polyimide varnish.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 1A, to obtain a film having a thickness of 16 μm. The results are shown in Table 1.

< example 2A >

BAFL 31.361g (0.090 mol), 3,5-DABA 1.522g (0.010 mol), and gamma-butyrolactone (Mitsubishi chemical Co., ltd.) 105.961g were charged into a 1L 5-neck round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a dean-Stark apparatus equipped with a condenser tube, a thermometer, and a glass end cap, and stirred at a temperature of 70℃in the system under a nitrogen atmosphere and a rotation speed of 200rpm, to obtain a solution.

To this solution were added CPODA 38.438g (0.100 mol) and gamma-butyrolactone (Mitsubishi chemical Co., ltd.) 26.490g at a time, and then, triethylamine (Kato chemical Co., ltd.) 0.506g and triethylenediamine (Tokyo chemical Co., ltd.) 0.056g as imidization catalysts were added, and the mixture was heated by a hood heater to raise the temperature in the reaction system to 190℃for about 20 minutes. The distilled-off components were collected, the rotation speed was adjusted according to the increase in viscosity, and the temperature in the reaction system was kept at 190℃for 3 hours for reflux.

Then, 478.614g of γ -butyrolactone (mitsubishi chemical Co., ltd.) was added, and the reaction system was cooled to 120℃and stirred for about 3 hours to homogenize the mixture, thereby obtaining a polyimide resin solution (2) having a solid content of 10.0% by mass.

Subsequently, 0.0796g (0.00037 mol) of 1,3-pbo as a crosslinking agent was added to 100g of the polyimide resin solution (2), and the mixture was stirred at room temperature for 1 hour to obtain a polyimide varnish containing the crosslinking agent and the polyimide resin and having a solid content of 10.07 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/2.

Then, the obtained polyimide varnish was applied to a glass plate, and the resultant was kept at 80℃for 20 minutes by a hot plate, and then heated in a hot air dryer at 350℃for 30 minutes under a nitrogen atmosphere to evaporate the solvent, thereby obtaining a film having a thickness of 27. Mu.m. The results are shown in Table 1.

< example 2B >

A polyimide varnish was produced in the same manner as in example 2A except that the amount of the crosslinking agent 1,3-PBO added to the polyimide resin solution (2) was changed to 0.1592g (0.00074 mol), and a polyimide varnish having a solid content concentration of 10.14 mass% including the crosslinking agent and the polyimide resin was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/1.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 2A, to obtain a film having a thickness of 23 μm. The results are shown in Table 1.

Comparative example 2 ]

A polyimide varnish was produced in the same manner as in example 2A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (2). That is, the polyimide resin solution (2) is directly used as a polyimide varnish.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 2A, to obtain a film having a thickness of 14 μm. The results are shown in Table 1.

< example 3A >

A polyimide resin solution was produced in the same manner as in example 2A except that the amount of BAFL was changed from 31.361g (0.090 mol) to 27.876g (0.080 mol) and the amount of 3,5-DABA was changed from 1.522g (0.010 mol) to 3.043g (0.020 mol), thereby obtaining a polyimide resin solution (3) having a solid content of 10.0 mass%.

Next, 0.1597 g (0.0007 mol) of 1,3-PBO as a crosslinking agent was added to 100g of the polyimide resin solution (3), and the mixture was stirred at room temperature for 1 hour to obtain a polyimide varnish containing the crosslinking agent and the polyimide resin in a solid content concentration of 10.14 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/2.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 2A, to obtain a film having a thickness of 24 μm. The results are shown in Table 1.

< example 3B >

A polyimide varnish was produced in the same manner as in example 3A except that the amount of the crosslinking agent 1,3-PBO added to the polyimide resin solution (3) was changed to 0.319g (0.0015 mol), and a polyimide varnish having a solid content concentration of 10.29 mass% including the crosslinking agent and the polyimide resin was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/1.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 3A, to obtain a film having a thickness of 23 μm. The results are shown in Table 1.

Comparative example 3 ]

A polyimide varnish was produced in the same manner as in example 3A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (3). Namely, the polyimide resin solution (3) is directly used as a polyimide varnish.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 3A, to obtain a film having a thickness of 20 μm. The results are shown in Table 1.

Example 4A ]

A polyimide resin solution (4) was produced in the same manner as in example 2A, except that the amount of BAFL was changed from 31.361g (0.090 mol) to 17.423g (0.050 mol) and the amount of 3,5-DABA was changed from 1.522g (0.010 mol) to 7.608g (0.050 mol).

Next, 0.4475 g (0.0021 mol) of 1,3-PBO as a crosslinking agent was added to 100g of the polyimide resin solution (4), and the mixture was stirred at room temperature for 1 hour to obtain a polyimide varnish having a solid content concentration of 10.40 mass% containing the crosslinking agent and the polyimide resin. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/2.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 2A, to obtain a film having a thickness of 12 μm. The results are shown in Table 1.

< example 4B >

A polyimide varnish was produced in the same manner as in example 4A except that the amount of the crosslinking agent 1,3-PBO added to the polyimide resin solution (4) was changed to 0.890g (0.0041 mol), and a polyimide varnish having a solid content concentration of 10.79 mass% including the crosslinking agent and the polyimide resin was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/1.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 4A, to obtain a film having a thickness of 15 μm. The results are shown in Table 1.

Comparative example 4 ]

A polyimide varnish was produced in the same manner as in example 4A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (4). That is, the polyimide resin solution (4) is directly used as a polyimide varnish.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 4A, to obtain a film having a thickness of 20 μm. The results are shown in Table 1.

Example 5 ]

A polyimide resin solution was produced in the same manner as in example 1A except that the amount of HPMDA was changed from 22.417g (0.100 mol) to 11.209g (0.050 mol) and cpoda19.219g (0.050 mol) was added thereto, to obtain a polyimide resin solution (5) having a solid content concentration of 10.0 mass%.

Next, 0.372g (0.0017 mol) of 1,3-PBO as a crosslinking agent was added to 100g of the polyimide resin solution (5), and the mixture was stirred at room temperature for 1 hour to obtain a polyimide varnish containing the crosslinking agent and the polyimide resin in a solid content concentration of 10.33 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/1.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 1A, to obtain a film having a thickness of 9. Mu.m. The results are shown in Table 1.

Comparative example 5 ]

A polyimide varnish was produced in the same manner as in example 5, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (5). Namely, the polyimide resin solution (5) is directly used as a polyimide varnish.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 5, to obtain a film having a thickness of 9. Mu.m. The results are shown in Table 1.

Example 6 ]

A polyimide resin solution (6) was prepared in the same manner as in example 1A except that the amount of HPMDA was changed from 22.417g (0.100 mol) to 20.175g (0.090 mol) and s-BPDA2.942g (0.010 mol) was additionally used.

Next, 0.424g (0.0020 mol) of 1,3-PBO as a crosslinking agent was added to 100g of the polyimide resin solution (6), and the mixture was stirred at room temperature for 1 hour to obtain a polyimide varnish having a solid content concentration of 10.38 mass% including the crosslinking agent and the polyimide resin. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/1.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 1A, to obtain a film having a thickness of 20 μm. The results are shown in Table 1.

Comparative example 6 ]

A polyimide varnish was produced in the same manner as in example 6, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (6). Namely, the polyimide resin solution (6) is directly used as a polyimide varnish.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 6, to obtain a film having a thickness of 17 μm. The results are shown in Table 1.

[ Table 1-1]

Table 1 (1/2)

[ tables 1-2]

Table 1 (2/2)

Comparative example 7A ]

A polyimide varnish was produced in the same manner as in example 1A except that the amount of the crosslinking agent added to the polyimide resin solution (1) was changed from 0.216g (0.001 mol) of 1,3-PBO to 0.500g (0.0017 mol) of TG, and a polyimide varnish having a solid content concentration of 10.45 mass% including the crosslinking agent and the polyimide resin was obtained.

Then, the polyimide varnish obtained was applied to a glass plate, and the resultant was kept at 80℃for 20 minutes by a hot plate, and then heated in a hot air dryer at 350℃for 30 minutes under a nitrogen atmosphere to evaporate the solvent, thereby obtaining a film having a thickness of 20. Mu.m. Point-like dead spots are seen on the whole surface of the obtained film. The results are shown in Table 2.

Comparative example 7B ]

A polyimide varnish was produced in the same manner as in comparative example 7A except that the amount of the crosslinking agent TG added to the polyimide resin solution (1) was changed to 1.000g (0.0034 mol), and a polyimide varnish having a solid content concentration of 10.89 mass% including the crosslinking agent and the polyimide resin was obtained.

Using the obtained polyimide varnish, a film was produced in the same manner as in comparative example 7A, to obtain a film having a thickness of 22. Mu.m. Point-like dead spots are seen on the whole surface of the obtained film. The results are shown in Table 2.

TABLE 2

Comparative example 8A ]

Into a 1L 5-neck round-bottom flask equipped with a stainless steel half-moon shaped stirring blade, a nitrogen inlet pipe, a dean-Stark apparatus equipped with a condenser, a thermometer, and a glass end cap were charged 10.615g (0.050 mol) of mTB, 7.608g (0.050 mol) of 3,5-DABA, and 48.767g of γ -butyrolactone (Mitsubishi chemical Co., ltd.) to obtain a solution by stirring at a temperature of 70℃in the system under a nitrogen atmosphere at a rotation speed of 200 rpm.

To this solution were added 22.417g (0.100 mol) of HPDA and 12.192g of N, N' -dimethylacetamide (Mitsubishi gas chemical Co., ltd.) at a time, and 0.506g of triethylamine (Kanto chemical Co., ltd.) as an imidization catalyst was added, and the mixture was heated by a hood heater to raise the temperature in the reaction system to 180℃over about 20 minutes. The distilled-off components were collected, the rotation speed was adjusted according to the increase in viscosity, and the temperature in the reaction system was kept at 180℃for 5 hours for reflux.

Then, 280.466g of N, N' -dimethylacetamide (Mitsubishi gas chemical Co., ltd.) was added, and the reaction system was cooled to 120℃and then stirred for about 3 hours to homogenize the mixture, thereby obtaining a polyimide resin solution (7) having a solid content of 10.0 mass%.

Next, 1.425g (0.0066 mol) of 1,3-PBO as a crosslinking agent was added to 100g of the polyimide resin solution (7), and the mixture was stirred at room temperature for 1 hour to obtain a polyimide varnish containing the crosslinking agent and the polyimide resin in a solid content concentration of 11.26 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA was 1/1.

Then, the polyimide varnish obtained was applied to a glass plate, and the resultant was kept at 80℃for 20 minutes by a hot plate, and then heated in a hot air dryer at 350℃for 30 minutes under a nitrogen atmosphere to evaporate the solvent, thereby obtaining a film having a thickness of 16. Mu.m. The results are shown in Table 3.

Comparative example 8B ]

A polyimide varnish was produced in the same manner as in comparative example 8A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (7). Namely, the polyimide resin solution (7) is directly used as a polyimide varnish.

Using the obtained polyimide varnish, a film was produced in the same manner as in comparative example 8A, to obtain a film having a thickness of 15. Mu.m. The results are shown in Table 3.

TABLE 3

TABLE 3 Table 3

As shown in table 1, the films of the examples were excellent in mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy.

In particular, it was confirmed that the organic solvent resistance was improved by adding 1,3-PBO (comparison of examples 1A and 1B with comparative example 1, comparison of examples 2A and 2B with comparative example 2, comparison of examples 3A and 3B with comparative example 3, comparison of examples 4A and 4B with comparative example 4, comparison of examples 5 with comparative example 5, and comparison of examples 6 with comparative example 6).

In addition, it was unexpectedly confirmed that: the optical isotropy can be maintained even by adding 1,3-PBO (comparison of examples 1A and 1B with comparative example 1), or the optical isotropy can be improved by adding 1,3-PBO (comparison of examples 2A and 2B with comparative example 2, comparison of examples 3A and 3B with comparative example 3, comparison of examples 4A and 4B with comparative example 4, comparison of example 5 with comparative example 5, and comparison of example 6 with comparative example 6).

The films obtained in comparative examples 7A and 7B using TG (not a crosslinking agent having at least 2 oxazolyl groups) as a crosslinking agent were not uniform films. This is thought to be due to poor compatibility of the polyimide resin with the additive TG, and separation occurs.

In addition, as shown in table 2, the film of comparative example 7B was very poor in colorless transparency.

In comparative examples 8A and 8B, BAFL (the compound represented by the formula (B-1)) was not used as the diamine component, but mTB was used instead. As a result, the optical isotropy of the films of comparative examples 8A and 8B obtained was poor. In addition, the film of comparative example 8B was poor in organic solvent resistance. As can be seen from comparative examples 8A and 8B, the addition of 1,3-PBO significantly deteriorated colorless transparency (total light transmittance, YI) although the organic solvent resistance was improved. As a result, the film of comparative example 8A was very poor in colorless transparency as compared with the film of example.

Claims

1. A polyimide resin composition comprising: a polyimide resin, and a crosslinking agent having at least 2 oxazolyl groups,

the constituent unit B includes: a constituent unit (B-1) derived from a compound represented by the following formula (B-1), and a constituent unit (B-2) derived from a compound represented by the following formula (B-2),

the polyimide resin composition contains the polyimide resin and the crosslinking agent in a molar ratio of oxazolyl groups in the crosslinking agent to carboxyl groups in the polyimide resin, i.e., in a ratio of oxazolyl groups/carboxyl groups in the range of 1/4 to 1/0.5,

in the formula (b-1), R is independently a hydrogen atom, a fluorine atom or a methyl group; in the formula (b-2), X is a single bond, a substituted or unsubstituted alkylene group, a carbonyl group, an ether group, a group represented by the following formula (b-2-i), or a group represented by the following formula (b-2-ii), p is an integer of 0 to 2, m1 is an integer of 0 to 4, m2 is an integer of 0 to 4, wherein when p is 0, m1 is an integer of 1 to 4,

In the formula (b-2-i), m3 is an integer of 0 to 5; in the formula (b-2-ii), m4 is an integer of 0 to 5, and m1+m2+m3+m4 is 1 or more, and when p is 2, 2X and 2 m2 to m4 are independently selected.

2. The polyimide resin composition according to claim 1, wherein the constituent unit (B-2) is a constituent unit (B-21) derived from a compound represented by the following formula (B-21),

3. the polyimide resin composition according to claim 1 or 2, wherein the crosslinking agent comprises a benzene ring to which the at least 2 oxazolyl groups are bonded.

4. The polyimide resin composition according to claim 1 or 2, wherein the ratio of the constituent unit (B-1) in the constituent unit B is 40 to 99 mol%,

5. The polyimide resin composition according to claim 1 or 2, wherein the ratio of the constituent unit (a-1) in the constituent unit a is 50 mol% or more.

6. The polyimide resin composition according to claim 1 or 2, wherein the constituent unit (a-1) is the constituent unit (a-1-1).

7. The polyimide resin composition according to claim 1 or 2, wherein the constituent unit (a-1) is the constituent unit (a-1-2).

8. A polyimide film obtained by crosslinking the polyimide resin in the polyimide resin composition according to any one of claims 1 to 7 with the crosslinking agent.