CN111683992A

CN111683992A - Polyimide resin composition and polyimide film

Info

Publication number: CN111683992A
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: 2020-09-18
Anticipated expiration: 2039-01-30
Also published as: KR102663662B1; WO2019151336A1; CN111683992B; TWI799505B; TW201934617A; JP7180617B2; KR20200118027A; JPWO2019151336A1

Abstract

The present invention provides a polyimide resin composition which can form a film having excellent mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy, and has excellent storage stability, and a polyimide film. Disclosed is a polyimide resin composition containing a polyimide resin and a crosslinking agent having at least 2 oxazole groups, wherein the polyimide resin contains a constituent unit A and a constituent unit B derived from a diamine, the constituent unit A contains a constituent unit (A-1), and the constituent unit (A-1-1) is 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 the polyimide resin in the polyimide resin composition with a crosslinking agentAt least 1 of the group of (a); 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, m2 is an integer of 0 to 4; wherein, when 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 therefore, various uses thereof in the fields of electric and electronic components and the like have been studied. For example, for the purpose of weight reduction and flexibility of devices, it is desired to replace a glass substrate used for an image display device such as a liquid crystal display and an OLED display with a plastic substrate, and a polyimide film suitable for the plastic substrate is being studied. The polyimide film for such applications is required to have colorless transparency.

Further, when a film having poor resistance to an organic solvent such as a polar solvent (organic solvent resistance) is exposed to an organic solvent such as a polar solvent, the film may be subjected to a morphological change due to elution or swelling of the surface thereof, and therefore, polyimide films are often required to have organic solvent resistance. 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 oxazole groups, and describes that a film having good transparency and high hardness can be formed from the polyimide resin composition.

Further, patent document 2 discloses a transparent flexible film containing: a polyimide copolymer having a carboxyl group, and a polyfunctional epoxy compound.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 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 (for example, a liquid crystal display, a touch panel, or the like), high optical isotropy is required in addition to the colorless transparency. However, patent document 1 does not describe any optical isotropy.

In patent document 2, an epoxy group of a polyfunctional epoxy compound added as a crosslinking agent reacts with a 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 progresses, and the storage stability is poor. In addition, the thermal decomposition temperature of epoxy resins is generally 250 to 350 ℃, and it is considered that the heat resistance is insufficient in applications requiring a high-temperature process.

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

Means for solving the problems

The inventors found that the method comprises the following steps: the above problems can be solved by a polyimide resin composition comprising a polyimide resin having a combination of specific constituent units and a specific crosslinking agent, and the present invention has been completed.

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 oxazole groups,

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

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),

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, 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; in the formula (b-2-ii), m1+ m2+ m3+ m4 is 1 or more; when p is 2, 2X and 2 m2 to m4 are independently selected, respectively.)

[2]

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

[4]

The polyimide resin composition according to any one of the above [1] to [3], which comprises the polyimide resin and the crosslinking agent in a ratio such that the molar ratio of the oxazolyl group in the crosslinking agent to the carboxyl group in the polyimide resin (oxazolyl group/carboxyl group) is in the 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 proportion 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 a 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 a 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 is excellent in storage stability, and can form a film excellent in mechanical properties, organic solvent resistance, 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. The polyimide resin and the crosslinking agent in the present invention will be described below.

< 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, 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), and 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).

(constituent Unit A)

The constituent unit A is a constituent unit derived from a tetracarboxylic dianhydride in a polyimide resin, and 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 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-cyclohexanetetracarboxylic dianhydride.

The compound represented by the formula (a-1-2) is norbornane-2-spiro- α -cyclopentanone- α' -spiro-2 ″ -norbornane-5, 5 ″,6,6 ″ -tetracarboxylic dianhydride.

When the constituent unit A contains the constituent unit (A-1), the colorless transparency of the film can be improved. When the constituent unit (A-1) includes 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). Further, the constituent unit (A-1) may be a combination of the constituent unit (A-1-1) and the constituent unit (A-1-2).

The proportion of the constituent unit (a-1) in the constituent unit a 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 proportion of the constituent unit (A-1) is not particularly limited, i.e., 100 mol%. The constituent unit A may include only the constituent unit (A-1).

The constituent unit A may include constituent units other than the constituent unit (A-1). The tetracarboxylic acid dianhydride which provides such a constituent unit is not particularly limited, and examples thereof include pyromellitic acid dianhydride, 3,3 ', 4, 4' -biphenyltetracarboxylic acid dianhydride, 2,3,3 ', 4' -biphenyltetracarboxylic acid dianhydride, 2 ', 3, 3' -biphenyltetracarboxylic acid dianhydride, 9 '-bis (3, 4-dicarboxyphenyl) fluorene dianhydride, 4, 4' - (hexafluoroisopropylidene) diphenyldicarboxylic acid dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 3,3 ', 4, 4' -diphenylsulfone tetracarboxylic acid dianhydride, 4,4 '-oxydiphthalic anhydride, 3, 3' -oxydiphthalic anhydride, and the like, Aromatic tetracarboxylic acid dianhydrides such as 3,3 ', 4, 4' -benzophenonetetracarboxylic acid dianhydride, 2 ', 3, 3' -benzophenonetetracarboxylic acid dianhydride, 4,4- (p-phenylenedioxy) dibenzoic acid dianhydride, and 4,4- (m-phenylenedioxy) dibenzoic acid 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)); and aliphatic tetracarboxylic acid dianhydrides such as 1,2,3, 4-butanetetracarboxylic acid dianhydride.

In the present specification, an aromatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing 1 or more aromatic rings, an alicyclic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing 1 or more alicyclic rings and no aromatic rings, and an aliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing neither aromatic rings nor alicyclic rings.

The constituent unit (a) may optionally include 1 or 2 constituent units other than the constituent unit (a-1).

As a preferred embodiment of the constituent unit other than the constituent unit (A-1), there can be mentioned the constituent unit (A-2) derived from a compound represented by the following formula (a-2).

The compound represented by the formula (a-2) is biphenyltetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride (s-BPDA) represented by the following formula (a-2s), 2,3,3 ', 4' -biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a-2a), and 2,2 ', 3, 3' -biphenyltetracarboxylic 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%, and 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%, and 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 the 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; 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. it is to be noted that m1+ m2+ m3+ m4 is 1 or more, and when p is 2, 2X and 2 m2 to m4 are independently selected, respectively.)

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, and 9, 9-bis (3-methyl-4-aminophenyl) fluorene, 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 formulae (b-21) to (b-27).

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

The constituent unit (B-2) is a constituent unit that provides a carboxyl group to the polyimide resin. The polyimide resin has a carboxyl group, and thus crosslinking between the polyimide resins by a crosslinking agent described later becomes possible. Therefore, when the constituent unit (B) includes the constituent unit (B-2), 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%, and particularly preferably 80 to 90 mol%.

The proportion 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%, and particularly preferably 10 to 20 mol%.

The ratio of the total of the constituent unit (B-1) and the constituent unit (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, i.e., 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 constitutional unit is not particularly limited, and examples thereof include 1, 4-phenylenediamine, p-xylylenediamine, 2 ' -dimethylbiphenyl-4, 4 ' -diamine, 2 ' -bis (trifluoromethyl) benzidine, 4 ' -diaminodiphenyl ether, 4 ' -diamino-2, 2 ' -bistrifluoromethyldiphenyl ether, 4 ' -diaminodiphenylmethane, 2-bis (4-aminophenyl) hexafluoropropane, bis (4-aminophenyl) sulfone, 4 ' -diaminobenzanilide, 1- (4-aminophenyl) -2, 3-dihydro-1, 3, 3-trimethyl-1H-indene-5-amine, α ' -bis (4-aminophenyl) -1, aromatic diamines such as 4-diisopropylbenzene, N ' -bis (4-aminophenyl) terephthalamide, 4 ' -bis (4-aminophenoxy) biphenyl, 2-bis [ 4- (4-aminophenoxy) phenyl ] propane, 2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 5 ' - (1,1,1,3,3, 3-hexafluoro-2-hydroxyisopropyl) -2,2 ' -dimethylbiphenyl-4, 4 ' -diamine and 9, 9-bis (4- (4-aminophenoxy) phenyl) fluorene (except for the compound represented by formula (b-1) and the compound represented by formula (b-2)); alicyclic diamines such as 1, 3-bis (aminomethyl) cyclohexane and 1, 4-bis (aminomethyl) cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine.

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

The constituent unit (B) may optionally contain 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 polyimide film to be obtained. The number average molecular weight of the polyimide resin can be determined, for example, based on a standard polymethyl methacrylate (PMMA) conversion value measured by gel filtration chromatography.

< method for producing polyimide resin >

In the present invention, the 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 containing: a compound which provides the above-mentioned constituent unit (B-1) and a compound which provides 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.

Examples of the compound that can provide the constituent unit (A-1-1) include compounds represented by the formula (a-1-1), but the compound is not limited thereto, and derivatives thereof may be provided as long as the same constituent unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to a tetracarboxylic dianhydride represented by the formula (a-1-1) (i.e., 1,2,4, 5-cyclohexanetetracarboxylic acid) and an alkyl ester of the tetracarboxylic acid. As the compound providing the constituent unit (A-1-1), a compound represented by the formula (a-1-1) (i.e., dianhydride) is preferable.

Examples of the compound that can provide the constituent unit (A-1-2) include compounds represented by the formula (a-1-2), but the compound is not limited thereto, and derivatives thereof may be provided in the range that provides the same constituent unit. Examples of the derivative include a tetracarboxylic acid corresponding to a 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 that provides the constituent unit (A-1), only the compound that provides the constituent unit (A-1-1) may be used, or only the compound that provides the constituent unit (A-1-2) may be used.

Further, as the compound which can provide the constituent unit (A-1), a combination of a compound which can provide the constituent unit (A-1-1) and a compound which can provide the constituent unit (A-1-2) can also 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 that provides the constituent unit (a-1). The upper limit of the content of the compound constituting the unit (A-1) is not particularly limited, i.e., 100 mol%. The tetracarboxylic acid component may contain only a compound which provides the constituent unit (A-1).

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

The tetracarboxylic acid component may optionally contain 1 or 2 or more compounds other than the compound providing the constituent unit (A-1).

As a preferred embodiment of the compound other than the compound which provides the constituent unit (A-1), there can be mentioned a compound which provides the constituent unit (A-2).

Examples of the compound that provides the constituent unit (A-2) include compounds represented by the formula (a-2), but the compound is not limited thereto, and derivatives thereof may be provided as long as the same constituent unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to a tetracarboxylic dianhydride represented by the formula (a-2) and an alkyl ester of the tetracarboxylic acid. As the compound providing the constituent unit (A-2), a compound represented by the formula (a-2) (i.e., dianhydride) is preferred.

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

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

Examples of the compound that can provide the constituent unit (B-1) include compounds represented by the formula (B-1), but the compound is not limited thereto, and derivatives thereof may be provided as long as 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.

Examples of the compound that can provide the constituent unit (B-2) include compounds represented by the formula (B-2), but the compound is not limited thereto, and derivatives thereof may be provided as long as 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%, even more preferably 75 to 95 mol%, and particularly preferably 80 to 90 mol% of a compound that provides the constituent unit (B-1).

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

The diamine component contains 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 of the total of the compound that provides the constituent unit (B-1) and the compound that provides the constituent unit (B-2). The upper limit of the total content of the compound that provides the constituent unit (B-1) and the compound that provides the constituent unit (B-2) is not particularly limited, i.e., 100 mol%. The diamine component may contain only the compound that provides the constituent unit (B-1) and the compound that provides the constituent unit (B-2).

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

The diamine component may optionally contain 1 or 2 or more compounds other than the compound that provides the constituent unit (B-1) and the compound that provides the constituent unit (B-2).

In the present invention, the amount ratio of the tetracarboxylic acid component and the diamine component to be used for producing the polyimide resin is preferably 0.9 to 1.1 mol of the diamine component to 1 mol of the tetracarboxylic acid component.

In the present invention, in addition to the tetracarboxylic acid component and the diamine component described above, an end-capping agent may be used for the production of the polyimide resin. As the end-capping agent, monoamines or dicarboxylic acids are preferred. The amount of the end-capping agent to be introduced is preferably 0.0001 to 0.1 mol, and particularly preferably 0.001 to 0.06 mol, based on 1 mol of the tetracarboxylic acid component. As the monoamine-type blocking agent, 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. As the dicarboxylic acid-based end capping agent, dicarboxylic acids are preferred, and a part thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2, 3-benzophenonedicarboxylic acid, 3, 4-benzophenonedicarboxylic acid, cyclohexane-1, 2-dicarboxylic acid, cyclopentane-1, 2-dicarboxylic acid, 4-cyclohexene-1, 2-dicarboxylic acid, and the like are recommended. Among these, phthalic acid and phthalic anhydride can be suitably used.

The method for reacting the tetracarboxylic acid component with the diamine component is not particularly limited, and a known method can be used.

Specific reaction methods include the following methods: (1) a method of charging a tetracarboxylic acid component, a diamine component, and a reaction solvent into a reactor, stirring at room temperature to 80 ℃ for 0.5 to 30 hours, and then raising the temperature to perform an imidization reaction, (2) a method of charging a diamine component and a reaction solvent into a reactor, dissolving the diamine component and the reaction solvent, then charging a tetracarboxylic acid component, stirring at room temperature to 80 ℃ for 0.5 to 30 hours, if necessary, and then raising the temperature to perform an imidization reaction, and (3) a method of charging a tetracarboxylic acid component, a diamine component, and a reaction solvent into a reactor, and immediately raising the temperature to perform an imidization reaction.

The reaction solvent used for producing the polyimide resin may be any solvent which can dissolve the polyimide resin produced without inhibiting the imidization reaction. Examples thereof include aprotic solvents, phenol solvents, ether solvents, carbonate solvents and the like.

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, and tetramethylurea, lactone solvents such as γ -butyrolactone and γ -valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphinotriamide, 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 acetic acid (2-methoxy-1-methylethyl).

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

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, and propylene carbonate.

Among the above reaction solvents, an amide solvent or a lactone 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 carry out the reaction while removing the water produced during the production. By performing such an operation, the degree of polymerization and the imidization ratio can be further increased.

In the imidization reaction, a known imidization catalyst can be used. Examples of the imidization catalyst include an alkali 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 and N, N-diethylaniline, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogen carbonate and sodium hydrogen carbonate.

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.

Among the above, from the viewpoint of handling properties, a base catalyst is preferably used, an organic base catalyst is more preferably used, triethylamine is further preferably used, and a combination of triethylamine and triethylenediamine is particularly preferably used.

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

< crosslinking agent >

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

Since the polyimide resin contained in the polyimide resin composition of the present invention has a carboxyl group, when the polyimide resin composition of the present invention is heated, the polyimide resins are crosslinked with each other by the crosslinking agent to form 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, 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 Nippon Kabushiki Kaisha, 2, 6-bis (4-isopropyl-2-oxazoline-2-yl) pyridine, 2, 6-bis (4-phenyl-2-oxazoline-2-yl) pyridine, 2 ' -isopropylidenebis (4-phenyl-2-oxazoline), and 2,2 ' -isopropylidenebis (4-tert-butyl-2-oxazoline).

The crosslinking agent is preferably a compound containing an aromatic ring or an aromatic heterocycle 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 two or more of them may be used in combination.

The polyimide resin composition of the present invention preferably comprises: 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 group/carboxyl group) is in the range of 1/4-1/0.5. The molar ratio is more preferably 1/4 to 1/1, and still more preferably 1/2 to 1/1.

The molar ratio is: 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 for the production of the polyimide resin is calculated based on the amount of the crosslinking agent and the amount of the compound providing the constituent unit (B-2).

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

The organic solvent is not particularly limited as long as the polyimide resin is dissolved, and it is preferable to use the compound described above as the reaction solvent used for producing the polyimide resin alone or in combination of 2 or more.

The polyimide varnish may be a solution itself obtained by dissolving a polyimide resin obtained by a polymerization method in a reaction solvent, and may be a solution obtained by adding a diluent 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, the polyimide varnish can be used in a high concentration which is stable at room temperature. The polyimide varnish preferably contains 5 to 40 mass% of a polyimide resin, and more preferably 10 to 30 mass%. The viscosity of the polyimide varnish is preferably 1 to 200 pas, more preferably 5 to 150 pas. The viscosity of the polyimide varnish was measured at 25 ℃ using an E-type viscometer.

The polyimide resin composition of the present invention may contain various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, antifoaming agents, optical brighteners, crosslinking agents, polymerization initiators, and photosensitizers, as long as the required properties of the polyimide film are not impaired.

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 having excellent mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy. Preferred physical property values of the film formed by 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 further 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 further preferably 2.2 or less when a film having a thickness of 10 μm is formed.

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

The tensile strength, tensile elastic modulus, total light transmittance, Yellowness Index (YI), and retardation by thickness (Rth) in the present invention can be measured specifically 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 the preferred physical property values 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 a polyimide resin at a temperature at which a crosslinking reaction between the polyimide resin and a crosslinking agent proceeds (preferably 80 ℃ or higher, more preferably 100 ℃ or higher, and further preferably 150 ℃ or higher). Examples thereof include: a method of applying the polyimide varnish described above to a smooth support such as a glass plate, a metal plate, or a plastic, or molding the polyimide varnish into a film and heating the film. 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, a release agent may be applied to the surface of the support in advance.

Examples of the method for applying the polyimide varnish to the support include known application methods such as spin coating, slit coating, and blade coating.

The following method is preferable as the heat treatment. Namely, it is preferable that: the polyimide film is produced by evaporating an organic solvent at a temperature of 60 to 150 ℃ to form a self-supporting film, peeling the self-supporting film from a support, fixing the end of the self-supporting film, and drying the film at a temperature not lower than the boiling point of the organic solvent used. Further, it is preferable to perform drying under a nitrogen atmosphere. The pressure of the drying atmosphere may be reduced pressure, normal pressure or increased pressure. The heating temperature for producing the polyimide film by drying the self-supporting film is not particularly limited, and is preferably 250 to 400 ℃.

The thickness of the polyimide film of the present invention can be suitably selected depending on the application, and is preferably 1 to 250. mu.m, more preferably 5 to 100. mu.m, and still more preferably 10 to 80 μm. The thickness is 1 to 250 μm, and thus 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 content 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 components, and optical members. The polyimide film of the present invention is particularly suitable for use as a substrate for an image display device such as a liquid crystal display, an OLED display, or the like.

Examples

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples.

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

(1) Concentration of solid component

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

(2) Thickness of film

The film thickness was measured using a micrometer manufactured by Sanfeng corporation.

(3) Tensile Strength and tensile elastic modulus

The measurement was carried out in accordance with JIS K7127 using a tensile tester "Strogaph VG-1E" manufactured by Toyo Seiki Kabushiki Kaisha.

(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 "COH 400" manufactured by Nippon Denshoku industries Co., Ltd.

(5) Thickness retardation (Rth)

The thickness retardation (Rth) was measured using an ellipsometer "M-220" manufactured by Nippon spectral Co., Ltd. The value of the thickness retardation at a measurement wavelength of 590nm was measured. When nx is the maximum value and ny is the minimum value among the in-plane refractive indices of the polyimide film, nz is the refractive index in the thickness direction, and d is the thickness of the film, Rth is expressed by the following formula.

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 to evaluate the organic solvent resistance. N-methyl-2-pyrrolidone (NMP) was used as the organic solvent.

The evaluation criteria for organic solvent resistance are as follows.

B: when the film is immersed in the organic solvent for less than 3 hours, the film surface is dissolved.

A: even after 3 hours of immersion in an organic solvent, the surface of the film was not dissolved and changed.

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

< tetracarboxylic acid component >

HPMDA: 1,2,4, 5-Cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi gas chemical Co., Ltd.; Compound represented by the formula (a-1-1))

CpODA: norbornane-2-spiro- α -cyclopentanone- α' -spiro-2 "-norbornane-5, 5", 6,6 "-tetracarboxylic dianhydride (JX エネルギー, a compound represented by the formula (a-1-2))

s-BPDA: 3,3 ', 4, 4' -Biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi chemical Co., Ltd.; Compound represented by the formula (a-2 s))

< diamine component >

BAFL: 9, 9-bis (4-aminophenyl) fluorene (manufactured by Taoka chemical Co., Ltd.; Compound represented by formula (b-1))

3, 5-DABA: 3, 5-diaminobenzoic acid (available from Nippon gaku Kogyo Co., Ltd.; Compound represented by the formula (b-211))

mTB: 2,2 '-Dimethylbiphenyl-4, 4' -diamine (manufactured by セイカ K.K.)

< crosslinking agent >

1, 3-PBO: 1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene (MIKUNI PHARMACEUTICAL INDUSTRIALCO., LTD. manufactured)

TG: triglycidyl isocyanurate (manufactured by Tokyo chemical industry Co., Ltd.)

< example 1A >

A1L 5-neck round-bottom flask equipped with a stainless steel half-moon-shaped stirring blade, a nitrogen inlet tube, a dean-Stark apparatus equipped with a condenser tube, a thermometer, and a glass end cap was charged with BAFL 27.876g (0.080 mol), 3,5-DABA3.043g (0.020 mol), and γ -butyrolactone (manufactured by Mitsubishi chemical corporation) 79.242g, and stirred at a system internal temperature of 70 ℃ and a nitrogen atmosphere at a rotation speed of 200rpm to obtain a solution.

To this solution, 22.417g (0.100 mol) of HPMDA and 19.811g of γ -butyrolactone (manufactured by Mitsubishi chemical corporation) were added at once, and 0.506g of triethylamine (manufactured by Kanto chemical corporation) as an imidization catalyst was charged, and the mixture was heated by a mantle heater to raise the temperature in the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the reaction mixture was refluxed for 3 hours while the rotation speed was adjusted in accordance with the increase in viscosity and the temperature in the reaction system was kept at 190 ℃.

Thereafter, 351.779g of gamma-butyrolactone (manufactured by Mitsubishi chemical corporation) was added, the temperature in the reaction system was cooled to 120 ℃, and the mixture was further stirred for about 3 hours to homogenize the mixture, thereby obtaining a polyimide resin solution (1) having a solid content concentration of 10.0 mass%.

Subsequently, 1,3-PBO0.216g (0.001 mol) 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 and having a solid content concentration of 10.2 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added was 1/2.

Then, the obtained polyimide varnish was coated on a glass plate, and the plate was kept at 80 ℃ for 20 minutes by a hot plate, and thereafter, the plate was heated at 350 ℃ for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, thereby obtaining a film having a thickness of 18 μm. 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 having a solid content concentration of 10.4 mass% comprising the crosslinking agent and the polyimide resin was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added 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 used as it is 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 >

A1L 5-neck round-bottomed flask equipped with a stainless steel half-moon-shaped stirring blade, a nitrogen inlet tube, a dean-Stark apparatus equipped with a condenser tube, a thermometer, and a glass end cap was charged with BAFL 31.361g (0.090 mol), 3,5-DABA1.522g (0.010 mol), and γ -butyrolactone (manufactured by Mitsubishi chemical corporation) 105.961g, and stirred at a system internal temperature of 70 ℃ and a nitrogen atmosphere at a rotation speed of 200rpm to obtain a solution.

To this solution were added 38.438g (0.100 mol) of CpODA and 26.490g of gamma-butyrolactone (manufactured by Mitsubishi chemical corporation) at once, and then 0.506g of triethylamine (manufactured by Kanto chemical corporation) and 0.056g of triethylenediamine (manufactured by Tokyo chemical industry Co., Ltd.) as an imidization catalyst were charged, 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 components were collected, and the reaction mixture was refluxed for 3 hours while the rotation speed was adjusted in accordance with the increase in viscosity and the temperature in the reaction system was kept at 190 ℃.

Thereafter, 478.614g of γ -butyrolactone (manufactured by Mitsubishi chemical corporation) was added, the temperature in the reaction system was cooled to 120 ℃, and the mixture was further stirred for about 3 hours to homogenize the mixture, thereby obtaining a polyimide resin solution (2) having a solid content concentration of 10.0 mass%.

Subsequently, 1,3-PBO0.0796g (0.00037 mol) 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 concentration of 10.07 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added was 1/2.

Then, the obtained polyimide varnish was coated on a glass plate, and the plate was kept at 80 ℃ for 20 minutes by a hot plate, and thereafter, the plate was heated at 350 ℃ for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, thereby obtaining a film having a thickness of 27 μm. 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% and containing the crosslinking agent and the polyimide resin was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added 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) was 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 prepared 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 concentration of 10.0 mass%.

Subsequently, 1,3-PBO0.159g (0.0007 mol) 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 and having a solid content concentration of 10.14 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added 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% and containing the crosslinking agent and the polyimide resin was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added 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). That is, the polyimide resin solution (3) was 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 was prepared 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), thereby obtaining a polyimide resin solution (4) having a solid content concentration of 10.0 mass%.

Subsequently, 1,3-PBO0.445g (0.0021 mol) 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% and containing the crosslinking agent and the polyimide resin. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added 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 containing the crosslinking agent and the polyimide resin and having a solid content concentration of 10.79 mass% was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added 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) was 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 prepared 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, thereby obtaining a polyimide resin solution (5) having a solid content concentration of 10.0 mass%.

Subsequently, 1,3-PBO0.372g (0.0017 mol) 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 and having a solid content concentration of 10.33 mass%. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added 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 μm. 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) was 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 μm. The results are shown in Table 1.

< example 6>

A polyimide resin solution 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 added to the solution, thereby obtaining a polyimide resin solution (6) having a solid content of 10.0 mass%.

Subsequently, 1,3-PBO0.424g (0.0020 mol) as a crosslinking agent was added to 100g of the polyimide resin solution (6), and after stirring at room temperature for 1 hour, a polyimide varnish containing the crosslinking agent and the polyimide resin and having a solid content concentration of 10.38 mass% was obtained. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added 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) was 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.

[ tables 1-1]

Table 1(1/2)

[ tables 1-2]

Table 1(2/2)

< comparative example 7A >

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

Then, the obtained polyimide varnish was coated on a glass plate, and the plate was kept at 80 ℃ for 20 minutes by a hot plate, and thereafter, the plate was heated at 350 ℃ for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, thereby obtaining a film having a thickness of 20 μm. The spot-like defect was observed over the entire 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% comprising 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, and a film having a thickness of 22 μm was obtained. The spot-like defect was observed over the entire surface of the obtained film. The results are shown in Table 2.

[ Table 2]

TABLE 2

< comparative example 8A >

10.615g (0.050 mol) of mTB, 3,5-DABA7.608g (0.050 mol) and 48.767g of gamma-butyrolactone (manufactured by Mitsubishi chemical Co., Ltd.) were put into a 1L 5-neck round-bottom flask equipped with a stainless steel semilunar stirring blade, a nitrogen introduction tube, a dean-Stark apparatus equipped with a condenser, a thermometer and a glass end cap, and stirred at a system internal temperature of 70 ℃ and a nitrogen atmosphere at a rotation speed of 200rpm to obtain a solution.

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

Thereafter, 280.466g of N, N' -dimethylacetamide (manufactured by Mitsubishi gas chemical Co., Ltd.) was added to the reaction system, and the temperature in the reaction system was cooled to 120 ℃ and then homogenized by stirring for about 3 hours to obtain a polyimide resin solution (7) having a solid content of 10.0 mass%.

Subsequently, 1,3-PBO1.425g (0.0066 mol) 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 having a solid content concentration of 11.26 mass% and containing the crosslinking agent and the polyimide resin. The molar ratio of oxazolyl group/carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added was 1/1.

Then, the obtained polyimide varnish was coated on a glass plate, and the plate was kept at 80 ℃ for 20 minutes by a hot plate, and thereafter, the plate was heated at 350 ℃ for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, thereby obtaining a film having a thickness of 16 μm. 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) was directly used as a polyimide varnish.

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

[ Table 3]

TABLE 3

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

In particular, it was confirmed that the addition of 1,3-PBO improves the resistance to organic solvents (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 example 5 with comparative example 5, and comparison of example 6 with comparative example 6).

In addition, it was surprisingly confirmed that: the optical isotropy can be maintained even with the addition of 1,3-PBO (comparison of examples 1A and 1B with comparative example 1), or improved by the addition of 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 (other than a crosslinking agent having at least 2 oxazole groups) as a crosslinking agent were not uniform films. This is considered to be due to poor compatibility of the polyimide resin with the additive TG, and separation occurred.

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

In comparative examples 8A and 8B, BAFL (compound represented by formula (B-1)) was not used as a diamine component, and mTB was used instead. As a result, the films of comparative examples 8A and 8B obtained had poor optical isotropy. In addition, the film of comparative example 8B had poor resistance to organic solvents. By comparing comparative example 8A and comparative example 8B, it was found that the addition of 1,3-PBO significantly deteriorated the colorless transparency (total light transmittance, YI) although the organic solvent resistance was improved. As a result, the film of comparative example 8A was much less colorless and transparent than the film of example.

Claims

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

the constituent unit A contains 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 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 each independently a hydrogen atom, a fluorine atom, or a methyl group; in the formula (b-2), X is a single bond, substituted or unsubstituted alkylene, carbonyl, ether group, group shown in the formula (b-2-i) or group shown in the formula (b-2-ii), p is an integer of 0-2, m1 is an integer of 0-4, m2 is an integer of 0-4, wherein when p is 0, m1 is an integer of 1-4,

in the formula (b-2-i), m3 is an integer of 0-5; in the formula (b-2-ii), m4 is an integer of 0 to 5, 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 any one of claims 1 to 3, comprising the polyimide resin and the crosslinking agent in a ratio in which a molar ratio of an oxazolyl group in the crosslinking agent to a carboxyl group in the polyimide resin (oxazolyl group/carboxyl group) is in a range of 1/4 to 1/0.5.

5. The polyimide resin composition according to any one of claims 1 to 4, wherein the proportion of the constituent unit (B-1) in the constituent unit B is 40 to 99 mol%,

6. The polyimide resin composition according to any one of claims 1 to 5, wherein a 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 claims 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 claims 1 to 6, wherein the constituent unit (A-1) is a 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 claims 1 to 8 with the crosslinking agent.