CN114245809B

CN114245809B - Polyimide resin composition, polyimide varnish and polyimide film

Info

Publication number: CN114245809B
Application number: CN202080058012.3A
Authority: CN
Inventors: 安孙子洋平; 石井健太郎; 三田寺淳
Original assignee: Mitsubishi Gas Chemical Co Inc
Current assignee: Mitsubishi Gas Chemical Co Inc
Priority date: 2019-08-20
Filing date: 2020-08-05
Publication date: 2024-07-09
Anticipated expiration: 2040-08-05
Also published as: CN114245809A; WO2021033544A1; JPWO2021033544A1; TW202112905A; JP7517342B2; KR20220051335A

Abstract

A polyimide resin composition comprising a polyimide resin and a crosslinking agent having at least 2 oxazolyl groups, wherein the polyimide resin has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine, the structural unit A comprises a structural unit (A-1) derived from CpODA, the structural unit B comprises a structural unit (B-1) derived from TFMB, and a structural unit (B-2) derived from a specific compound represented by 3, 5-DABA.

Description

Polyimide resin composition, polyimide varnish and polyimide film

Technical Field

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

Background

In general, polyimide resins have excellent 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 and an OLED display with a plastic substrate, and research on a polyimide film suitable as the plastic substrate is being advanced. Colorless transparency is required for polyimide films for such applications.

When a polyimide film is formed by heating and curing a varnish applied to a glass support or a silicon wafer, residual stress is generated in the polyimide film. When the residual stress of the polyimide film is large, warpage of the glass support and the silicon wafer occurs, and therefore, the polyimide film is also required to have a reduced residual stress.

However, polyimide films are not only colorless and transparent, but also have low residual stress and chemical resistance (e.g., acid resistance, alkali resistance, solvent resistance) for use in substrates. For example, when a polyimide film is used as a substrate for forming an ITO (Indium Tin Oxide) film, the polyimide film is required to have resistance to an acid used for etching the ITO film. When the acid resistance of the polyimide film is insufficient, the film may yellow, and the colorless transparency may be impaired.

In addition, for cleaning a support such as a glass plate (support coated with polyimide varnish) used for producing a polyimide film, an aqueous alkali solution such as an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution is mainly used. The washing with the aqueous alkali solution may be performed in a state where a polyimide film is formed on a support such as a glass plate. Therefore, polyimide films also require resistance to alkali.

In addition, in the process of forming various electronic circuits such as TFTs on a polyimide film, an organic solvent such as NMP is sometimes used, and the polyimide film is also required to have resistance to the organic solvent.

On the other hand, after processing the polyimide resin composition into a polyimide film, piping and equipment used for coating and the like are required to be cleaned. In order to sufficiently clean the apparatus, the polyimide resin composition is required to have solubility in a cleaning liquid (for example, "OK73 thinner" manufactured by Tokyo applied chemical Co., ltd., various organic solvents such as NMP) and to have both solvent resistance and cleaning properties.

As a polyimide resin providing a film with low residual stress, patent document 1 discloses a polyimide resin synthesized using 4,4 '-oxydiphthalic dianhydride as a tetracarboxylic acid component and using α, ω -aminopropyl polydimethylsiloxane having a number average molecular weight of 1000 and 4,4' -diaminodiphenyl ether as a diamine component.

Patent document 2 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.

However, patent document 1 does not describe chemical resistance and cleaning performance. In patent document 2, the resistance to the solvent (N, N-dimethylacetamide) was not evaluated, and the cleaning property and the residual stress were not examined at all.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2005-232383

Patent document 2: japanese patent laid-open publication 2016-222797

Disclosure of Invention

Problems to be solved by the invention

As described above, the polyimide film is required to have colorless transparency, low residual stress, and chemical resistance, but it is not easy to improve these properties while maintaining excellent heat resistance.

The present invention aims to provide a polyimide resin composition capable of forming a film excellent in heat resistance, colorless transparency, chemical resistance and cleaning properties and having low residual stress, and a polyimide varnish and a polyimide film comprising the polyimide resin composition.

Solution for solving the problem

The inventors found that: the polyimide resin composition comprising a polyimide resin having a combination of specific structural units and comprising a specific crosslinking agent can solve the above-mentioned problems, and thus the present invention has been completed.

That is, the present invention relates to the following <1> to <11>.

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

The polyimide resin has a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A comprises a structural unit (A-1) derived from a compound represented by the following formula (a-1), and the structural unit B comprises a structural unit (B-1) derived from a compound represented by the following formula (B-1) and a structural unit (B-2) derived from a compound represented by the following formula (B-2).

( 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. )

<2> The polyimide resin composition according to the above <1>, wherein the structural unit (B-2) is a structural 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 ratio of the structural unit (A-1) in the structural unit A is 40 mol% or more.

<4> The polyimide resin composition according to any one of the above <1> to <3>, wherein the ratio of the structural unit (B-1) in the structural unit B is 35 to 95 mol%,

The ratio of the structural unit (B-2) in the structural unit B is 5 to 65 mol%.

<5> The polyimide resin composition according to any one of the above <1> to <4>, wherein the structural unit A further comprises a structural unit (A-2) derived from a compound represented by the following formula (a-2).

<6> The polyimide resin composition according to any one of the above <1> to <5>, wherein the structural unit A further comprises a structural unit (A-3) derived from an acid anhydride-modified silicone at both ends.

<7> The polyimide resin composition according to any one of the above <1> to <6>, wherein the crosslinking agent is a compound comprising an aromatic ring or an aromatic heterocyclic ring to which at least 2 oxazolyl groups are bonded.

<8> The polyimide resin composition according to any one of the above <1> to <7>, wherein the crosslinking agent is a compound comprising a benzene ring bonded with at least 2 oxazolyl groups.

<9> The polyimide resin composition according to any one of the above <1> to <8>, wherein the crosslinking agent is 1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene.

<10> A polyimide varnish obtained by dissolving the polyimide resin composition according to any one of the above <1> to <9> in an organic solvent.

<11> A polyimide film obtained by crosslinking the polyimide resin in the polyimide resin composition according to any one of the above <1> to <9> with the crosslinking agent.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can form a film having excellent heat resistance, colorless transparency, chemical resistance and cleaning properties and further having low residual stress.

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 >

The polyimide resin of the present invention has a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A comprises a structural unit (A-1) derived from a compound represented by the following formula (a-1), and the structural unit B comprises a structural unit (B-1) derived from a compound represented by the following formula (B-1) and a structural unit (B-2) derived from a compound represented by the following formula (B-2).

(Structural unit A)

The structural unit A is a structural unit derived from tetracarboxylic dianhydride in a polyimide resin, and contains a structural unit (A-1) derived from a compound represented by the following formula (a-1).

The compound shown in the formula (a-1) is norbornane-2-spiro-alpha-cyclopentanone-alpha '-spiro-2' -norbornane-5, 5 ', 6' -tetracarboxylic dianhydride. By including the structural unit (A-1), the colorless transparency and heat resistance of the film are improved.

The ratio of the structural unit (a-1) in the structural unit a is preferably 40 mol% or more, more preferably 50 mol% or more, and still more preferably 60 mol% or more. The upper limit of the ratio of the structural unit (A-1) is not particularly limited, that is, 100 mol%. The structural unit A may also contain only the structural unit (A-1).

The structural unit A may also contain structural units other than the structural unit (A-1).

The structural unit A preferably contains, in addition to the structural unit (A-1), a structural unit (A-2) derived from a compound represented by the following formula (a-2).

The compound represented by the formula (a-2) is 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). The 3,3',4' -biphenyltetracarboxylic dianhydride is preferable because it can reduce the residual stress of the polyimide film of the present invention.

When the structural unit A includes the structural unit (A-1) and the structural unit (A-2), the ratio of the structural unit (A-1) in the structural unit A is preferably 40 to 95 mol%, more preferably 50 to 90 mol%, further preferably 55 to 85 mol%, and the ratio of the structural unit (A-2) in the structural unit A is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, further preferably 15 to 45 mol%.

The total ratio of the structural units (A-1) and (A-2) in the structural unit A is preferably 50mol% 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 structural units (A-1) and (A-2) is not particularly limited, and is 100 mol%. The structural unit A may also contain only the structural unit (A-1) and the structural unit (A-2).

By further including the structural unit (A-2), the residual stress is further reduced.

In addition, by further including the structural unit (A-2), the transmittance of the film at the wavelength of 308nm is reduced. In recent years, as a method of separating a resin film from a support among supports laminated with the resin film, a laser separation process called laser separation (LLO) has been attracting attention. The smaller the light transmittance at the wavelength of 308nm, the more excellent the laser peelability by the XeCl excimer laser at the wavelength of 308 nm.

In the structural unit A, it is preferable that the structural unit (A-3) derived from both terminal acid anhydride-modified silicone is contained in addition to the structural unit (A-1).

As the both terminal acid anhydride-modified silicone, a compound represented by the following formula (a-3) is preferable.

(In the formula (a-3),

R ¹～R⁶ is a monovalent hydrocarbon group having 1 to 20 carbon atoms,

L ¹ and L ² are each independently a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms,

Z ¹ and Z ² are each independently a trivalent hydrocarbon group having 1 to 20 carbon atoms,

N is 1 to 200. )

R ¹～R⁶ in the formula (a-3) is a monovalent hydrocarbon group having 1 to 20 carbon atoms.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, and the like.

The alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl and hexyl. Cycloalkyl groups having 3 to 20 carbon atoms are preferable, and examples thereof include cyclopentyl and cyclohexyl. The aryl group having 6 to 20 carbon atoms is preferably an aryl group having 6 to 10 carbon atoms, and examples thereof include phenyl and naphthyl. The aralkyl group having 7 to 20 carbon atoms is preferably an aralkyl group having 7 to 10 carbon atoms, and examples thereof include benzyl and phenethyl. The alkenyl group having 2 to 20 carbon atoms is preferably an alkenyl group having 2 to 10 carbon atoms, and examples thereof include vinyl, allyl, propenyl, isopropenyl and butenyl.

R ¹～R⁶ is each independently preferably selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms and an alkenyl group having 2 to 20 carbon atoms; more preferably, the aromatic hydrocarbon is selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms and an alkenyl group having 2 to 10 carbon atoms; more preferably, the aromatic hydrocarbon is selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms and an alkenyl group having 2 to 10 carbon atoms; particularly preferably selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, phenyl, naphthyl, vinyl, allyl, propenyl, isopropenyl and butenyl; most preferred is the group consisting of methyl, ethyl, phenyl and vinyl.

L ¹ and L ² in the formula (a-3) are each independently a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms include an alkylene group having 1 to 20 carbon atoms, a cycloalkylene group (cycloalkylene) having 3 to 20 carbon atoms, and an arylene group having 6 to 20 carbon atoms.

The alkylene group having 1 to 20 carbon atoms is preferably an alkylene group having 1 to 10 carbon atoms, and examples thereof include methylene, ethylene, propylene, butylene, pentylene and hexylene.

The cycloalkyl group having 3 to 20 carbon atoms is preferably a cycloalkyl group having 3 to 10 carbon atoms, and examples thereof include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group and a cycloheptylene group.

The arylene group having 6 to 20 carbon atoms is preferably an arylene group having 6 to 10 carbon atoms, and examples thereof include phenylene and naphthylene.

L ¹ and L ² are each independently preferably selected from the group consisting of a single bond, an alkylene group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, and an arylene group having 6 to 20 carbon atoms; more preferably selected from the group consisting of a single bond, an alkylene group having 1 to 10 carbon atoms, a cycloalkylene group having 3 to 10 carbon atoms, and an arylene group having 6 to 10 carbon atoms; more preferably selected from the group consisting of a single bond, an alkylene group having 1 to 10 carbon atoms, and an arylene group having 6 to 10 carbon atoms; particularly preferably selected from the group consisting of single bond, methylene, ethylene, propylene, butylene, pentylene, hexylene, phenylene and naphthylene; most preferably selected from the group consisting of single bond, methylene, ethylene, propylene and phenylene.

Z ¹ and Z ² in the formula (a-3) are each independently a trivalent hydrocarbon group having 1 to 20 carbon atoms.

Z ¹ and Z ² are each independently preferably selected from the group consisting of a group represented by the following formula (a-3-i), a group represented by the following formula (a-3-ii), a group represented by the following formula (a-3-iii), and a group represented by the following formula (a-3-iv).

The group represented by the formula (a-3-i) is a succinic acid residue, the group represented by the formula (a-3-ii) is a phthalic acid residue, the group represented by the formula (a-3-iii) is a2, 3-norbornanedicarboxylic acid residue, and the group represented by the formula (a-3-iv) is a 5-norbornene-2, 3-dicarboxylic acid residue. In the formulae (a-3-i) to (a-3-iv), the "x" represents a bonding position.

N in the formula (a-3) is 1 to 200.n is preferably 3 to 150, more preferably 5 to 120.

Examples of commercially available both terminal acid anhydride-modified silicones which can be obtained include "X22-168AS", "X22-168A", "X22-168B" and "X22-168-P5-8" manufactured by Kagaku Kogyo Co., ltd., and "DMS-Z21" manufactured by Gelest Co., ltd.

When the structural unit A includes the structural unit (A-1) and the structural unit (A-3), the ratio of the structural unit (A-1) in the structural unit A is preferably 50 to 99 mol%, more preferably 60 to 98 mol%, still more preferably 70 to 97 mol%, and the ratio of the structural unit (A-3) in the structural unit A is preferably 1 to 50 mol%, more preferably 2 to 40 mol%, still more preferably 3 to 30 mol%.

The total ratio of the structural units (A-1) and (A-3) in the structural 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 total ratio of the structural units (A-1) and (A-3) is not particularly limited, and is 100 mol%. The structural unit A may also contain only the structural unit (A-1) and the structural unit (A-3).

By further including the structural unit (a-3), the residual stress of the film can be kept low, and the colorless transparency can be improved.

In addition, the structural unit A preferably contains both the structural unit (A-2) and the structural unit (A-3) in addition to the structural unit (A-1).

When the structural unit A includes the structural unit (A-1), the structural unit (A-2) and the structural unit (A-3), the ratio of the structural unit (A-1) in the structural unit A is preferably 50 to 90 mol%, more preferably 60 to 85 mol%, still more preferably 65 to 80 mol%, the ratio of the structural unit (A-2) in the structural unit A is preferably 5 to 30 mol%, more preferably 5 to 25 mol%, still more preferably 5 to 20 mol%, and the ratio of the structural unit (A-3) in the structural unit A is preferably 1 to 25 mol%, more preferably 2 to 20 mol%, still more preferably 3 to 15 mol%.

The total ratio of the structural units (A-1) to (A-3) in the structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the total ratio of the structural units (A-1) to (A-3) is not particularly limited, and is 100 mol%. The structural unit A may also contain only the structural unit (A-1), the structural unit (A-2) and the structural unit (A-3).

The structural units other than the structural unit (A-1) optionally contained in the structural unit A are not limited to the structural units (A-2) and (A-3). The tetracarboxylic dianhydride providing such an optional structural unit is not particularly limited, and examples thereof include aromatic tetracarboxylic dianhydrides such as pyromellitic dianhydride, 9 '-bis (3, 4-dicarboxyphenyl) fluorene dianhydride and 4,4' - (hexafluoroisopropylidene) dianhydride; alicyclic tetracarboxylic dianhydrides such as 1,2,3, 4-cyclobutane tetracarboxylic dianhydride and 1,2,4, 5-cyclohexane tetracarboxylic dianhydride (excluding the compound represented by the formula (a-1)); 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 number of structural units other than the structural unit (A-1) optionally contained in the structural unit A may be 1 or 2 or more.

(Structural unit B)

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

In the formulae (b-2-i) and (b-2-ii), the "x" represents a bonding position.

The compound represented by the formula (b-1) is 2,2' -bis (trifluoromethyl) benzidine. By including the structural unit (B-1) in the structural unit B, the colorless transparency of the film is improved and the residual stress is reduced.

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

Specific examples of the compound represented by the formula (b-21) include a compound represented by the following formula (b-211), namely, 3, 5-diaminobenzoic acid.

The structural unit (B-2) is preferably a structural unit (B-21) derived from a compound represented by the formula (B-21), more preferably a structural unit (B-211) derived from a compound represented by the formula (B-211).

By including the structural unit (B-2), the heat resistance of the film is improved.

The ratio of the structural unit (B-1) in the structural unit B is preferably 35 to 95 mol%, more preferably 40 to 90 mol%, and still more preferably 45 to 85 mol%.

The ratio of the structural unit (B-2) in the structural unit B is preferably 5 to 65 mol%, more preferably 10 to 60 mol%, and still more preferably 15 to 55 mol%.

The total ratio of the structural units (B-1) and (B-2) in the structural 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 structural units (B-1) and (B-2) is not particularly limited, and is 100 mol%. The structural unit B may also comprise only the structural unit (B-1) and the structural unit (B-2).

The structural unit B may also comprise structural units other than the structural units (B-1) and (B-2). The diamine providing such a structural unit is not particularly limited, examples thereof include 1, 4-phenylenediamine, p-xylylenediamine, 1, 5-diaminonaphthalene, 2' -dimethylbiphenyl-4, 4' -diamine, 4' -diaminodiphenyl ether, 4' -diaminodiphenylmethane 2, 2-bis (4-aminophenyl) hexafluoropropane, 4' -diaminodiphenyl sulfone, 4' -diaminoanilide, 1- (4-aminophenyl) -2, 3-dihydro-1, 3-trimethyl-1H-inden-5-amine, alpha, aromatic diamines such as α ' -bis (4-aminophenyl) -1, 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, and 9, 9-bis (4-aminophenyl) fluorene (excluding 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 number of structural units other than the structural units (B-1) and (B-2) optionally contained in the structural unit B may be 1 or 2 or more.

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, from a standard polymethyl methacrylate (PMMA) conversion value measured by gel filtration chromatography.

The polyimide resin may contain a structure other than a polyimide chain (a structure in which a structural unit a and a structural unit B are imide-bonded). Examples of the structure other than the polyimide chain that can be contained in the polyimide resin include a structure containing an amide bond.

The polyimide resin preferably contains a polyimide chain (a structure in which a structural unit a and a structural unit B are imide-bonded) as a main structure. Therefore, the ratio of the polyimide chain in the polyimide resin is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and particularly preferably 99% by mass or more.

The polyimide resin composition of the present invention containing the polyimide resin can form a film excellent in heat resistance, colorless transparency, chemical resistance and cleaning properties and low in residual stress, and the film has the following suitable physical properties.

The glass transition temperature (Tg) is preferably 380℃or higher, more preferably 400℃or higher, and still more preferably 450℃or higher.

When a film having a thickness of 10 μm is formed, the total light transmittance is preferably 88% or more, more preferably 89% or more, and still more preferably 90% or more.

When a film having a thickness of 10 μm is produced, the Yellowness Index (YI) is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less.

The residual stress is preferably 25.0MPa, more preferably 24.0MPa, and still more preferably 22.0MPa or less.

Further, by using a polyimide resin in which the structural unit a further includes the structural unit (a-2) as one embodiment of the polyimide resin, a film having excellent laser peelability can be further formed, and the film has the following suitable physical properties.

When a film having a thickness of 10 μm is formed, the light transmittance at a wavelength of 308nm is preferably 0.8% or less, more preferably 0.6% or less, and still more preferably 0.4% or less.

The film formed using the polyimide resin has good mechanical properties and has the following suitable physical properties.

The tensile modulus is preferably 2.0GPa or more, more preferably 3.0GPa or more, and even more preferably 4.0GPa or more.

The tensile strength is preferably 80MPa or more, more preferably 100MPa or more, and still more preferably 120MPa or more.

The physical property values described above in the present invention can be measured by the methods described in the examples.

< 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 structural unit (A-1) with a diamine component containing a compound providing the above-mentioned structural unit (B-1) and a compound providing the above-mentioned structural unit (B-2).

The compound providing the structural unit (A-1) is exemplified by the compound represented by the formula (a-1), but is not limited thereto, and may be a derivative thereof within the range where the same structural unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-1) (i.e., norbornane-2-spiro- α -cyclopentanone- α' -spiro-2 "-norbornane-5, 5",6 "-tetracarboxylic acid) and an alkyl ester of the tetracarboxylic acid. As the compound providing the structural unit (A-1), a compound represented by the formula (a-1) (i.e., dianhydride) is preferable.

The tetracarboxylic acid component preferably contains 40 mol% or more, more preferably contains 50 mol% or more, still more preferably contains 60 mol% or more of the compound providing the structural unit (a-1). The upper limit of the content of the compound providing the structural unit (A-1) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may also contain only the compound providing the structural unit (A-1).

The tetracarboxylic acid component may contain compounds other than the compound providing the structural unit (A-1).

Among the tetracarboxylic acid components, it is preferable that the compound providing the structural unit (A-2) is contained in addition to the compound providing the structural unit (A-1).

The compound providing the structural 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 within the range where the same structural 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 providing the structural unit (A-2), a compound represented by the formula (a-2) (i.e., dianhydride) is preferable.

When the tetracarboxylic acid component contains the compound providing the structural unit (A-1) and the compound providing the structural unit (A-2), the tetracarboxylic acid component preferably contains 40 to 95 mol%, more preferably 50 to 90 mol%, still more preferably 55 to 85 mol%, of the compound providing the structural unit (A-1), preferably 5 to 60 mol%, more preferably 10 to 50 mol%, still more preferably 15 to 45 mol%, of the compound providing the structural unit (A-2).

The tetracarboxylic acid component contains the compound providing the structural unit (a-1) and the compound providing the structural unit (a-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 structural unit (A-1) and the compound providing the structural unit (A-2) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may also contain only the compound providing the structural unit (A-1) and the compound providing the structural unit (A-2).

Among the tetracarboxylic acid components, it is preferable that the compound providing the structural unit (A-3) is contained in addition to the compound providing the structural unit (A-1).

The compound providing the structural unit (A-3) may be a compound in which both ends of the structural unit are acid anhydride-modified, for example, a compound represented by the formula (a-3), but the compound is not limited thereto, and may be a derivative thereof within a range in which the same structural unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to the both terminal anhydride-modified silicone and an alkyl ester of the tetracarboxylic acid. As the compound providing the structural unit (A-3), a both terminal acid anhydride-modified silicone (i.e., dianhydride) is preferable.

When the tetracarboxylic acid component contains the compound providing the structural unit (A-1) and the compound providing the structural unit (A-3), the tetracarboxylic acid component preferably contains 50 to 99 mol%, more preferably contains 60 to 98 mol%, still more preferably contains 70 to 97 mol% of the compound providing the structural unit (A-1), preferably contains 1 to 50 mol%, more preferably contains 2 to 40 mol%, still more preferably contains 3 to 30 mol% of the compound providing the structural unit (A-3).

The tetracarboxylic acid component contains the compound providing the structural unit (A-1) and the compound providing the structural unit (A-3) in total, preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the total content of the compound providing the structural unit (A-1) and the compound providing the structural unit (A-3) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may also contain only the compound providing the structural unit (A-1) and the compound providing the structural unit (A-3).

The tetracarboxylic acid component preferably contains, in addition to the compound providing the structural unit (A-1), both a compound providing the structural unit (A-2) and a compound providing the structural unit (A-3).

When the tetracarboxylic acid component contains the compound providing the structural unit (A-1), the compound providing the structural unit (A-2) and the compound providing the structural unit (A-3), the tetracarboxylic acid component preferably contains 50 to 90 mol%, more preferably contains 60 to 85 mol%, still more preferably contains 65 to 80 mol% of the compound providing the structural unit (A-1), preferably contains 5 to 30 mol%, more preferably contains 5 to 25 mol%, still more preferably contains 5 to 20 mol% of the compound providing the structural unit (A-2), preferably contains 1 to 25 mol%, more preferably contains 2 to 20 mol%, still more preferably contains 3 to 15 mol% of the compound providing the structural unit (A-3).

The tetracarboxylic acid component contains the compound providing the structural unit (A-1), the compound providing the structural unit (A-2), and the compound providing the structural unit (A-3) 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 structural unit (A-1), the compound providing the structural unit (A-2) and the compound providing the structural unit (A-3) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may also contain only the compound providing the structural unit (A-1), the compound providing the structural unit (A-2), and the compound providing the structural unit (A-3).

The compounds other than the compound providing the structural unit (A-1) optionally contained in the tetracarboxylic acid component are not limited to the compound providing the structural unit (A-2) and the compound providing the structural unit (A-3). Examples of such optional compounds include the above-mentioned aromatic tetracarboxylic acid dianhydride, alicyclic tetracarboxylic acid dianhydride, aliphatic tetracarboxylic acid dianhydride, and derivatives thereof (tetracarboxylic acid, alkyl esters of tetracarboxylic acid, and the like).

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

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

Similarly, the compound represented by the formula (B-2) may be used as the compound for providing the structural unit (B-2), but the compound is not limited thereto, and may be a derivative thereof within the range for providing the same structural unit. The derivative may be a diisocyanate corresponding to the diamine represented by the formula (b-2). As the compound providing the structural unit (B-2), a compound represented by the formula (B-2) (i.e., diamine) is preferable.

The diamine component preferably contains 35 to 95 mol%, more preferably 40 to 90 mol%, still more preferably 45 to 85 mol% of the compound providing the structural unit (B-1).

The diamine component preferably contains 5 to 65 mol%, more preferably 10 to 60 mol%, still more preferably 15 to 55 mol% of the compound providing the structural unit (B-2).

The diamine component contains the compound providing the structural unit (B-1) and the compound providing the structural 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 structural unit (B-1) and the compound providing the structural unit (B-2) is not particularly limited, that is, 100 mol%. The diamine component may also contain only the compound providing the structural unit (B-1) and the compound providing the structural unit (B-2).

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

The number of compounds other than the compound providing the structural unit (B-1) and the compound providing the structural unit (B-2) optionally contained in the diamine component may be 1or 2or 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 used for producing 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: (1) A method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are fed into a reactor, stirred at room temperature to 80 ℃ for 0.5 to 30 hours, and then heated to perform imidization; (2) Adding diamine component and reaction solvent into a reactor to dissolve the components, adding tetracarboxylic acid component, stirring at room temperature to 80 ℃ for 0.5 to 30 hours as required, and heating to perform imidization reaction; (3) And a method in which the tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into a reactor, and the imidization reaction is performed by immediately raising the temperature.

The reaction solvent used for producing the polyimide resin may be one which does not inhibit imidization reaction and which can dissolve the polyimide to be 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 (NMP), N-methylcaprolactam, 1, 3-dimethylimidazolidinone, tetramethylurea, lactone solvents such as γ -butyrolactone (GBL), γ -valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphinotricin, sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide and sulfolane, ketone solvents such as acetone, cyclohexanone and methylcyclohexanone, amine solvents such as picoline and pyridine, ester solvents such as acetic acid (2-methoxy-1-methylethyl) ester, and the like.

Specific examples of the phenol-based solvent include phenol, o-cresol, m-cresol, p-cresol, 2, 3-xylenol, 2, 4-xylenol, 2, 5-xylenol, 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 above reaction solvents 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 (TEA), 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 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 bond is formed as shown below. This reaction is particularly easy to carry out when heated to 80℃or higher.

Since the polyimide resin contained in the polyimide resin composition of the present invention has carboxyl groups, when the polyimide resin composition of the present invention is heated, the polyimide resins are crosslinked with each other by a crosslinking agent to form a crosslinked polyimide resin. For this reason, the chemical resistance of the film is improved.

The crosslinking agent is not particularly limited as long as it is a polyfunctional oxazoline 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 Japanese catalyst, co., ltd., 2, 6-bis (4-isopropyl-2-oxazolin-2-yl) pyridine, 2, 6-bis (4-phenyl-2-oxazolin-2-yl) pyridine, 2' -isopropylidene bis (4-phenyl-2-oxazoline), 2' -isopropylidene bis (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 or a pyridine ring to which at least 2 oxazolyl groups are bonded, still more preferably a compound containing a benzene ring to which at least 2 oxazolyl groups are bonded, and particularly preferably 1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene.

The crosslinking agent may be used alone, or 2 or more kinds may be used in combination.

The polyimide resin composition of the present invention preferably 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 (oxazolyl/carboxyl groups) in the range of 1/8 to 1/0.5. The molar ratio is more preferably 1/6 to 1/1, and still more preferably 1/4 to 1/2.

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 structural unit (B-1) used in the production of the polyimide resin is calculated based on the addition amount of the crosslinking agent and the addition amount of the compound providing the structural unit (B-1).

[ Polyimide varnish ]

A preferred embodiment of the polyimide resin composition of the present invention is as follows: the polyimide resin composition (hereinafter also referred to as "polyimide varnish") contains an organic solvent in addition to the polyimide resin and the crosslinking agent, and is obtained by dissolving the polyimide resin in the organic solvent.

The organic solvent is not particularly limited as long as it can dissolve the polyimide resin, and the above-mentioned compounds are preferably used alone or in combination of 2 or more as the reaction solvent used in the production of the polyimide resin.

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 varnish preferably contains 5 to 40 mass%, more preferably 7 to 30 mass%, and still more preferably 8 to 20 mass% of a polyimide resin. The viscosity of the polyimide varnish is preferably 50 to 5000pa·s, more preferably 100 to 4000pa·s, and even more preferably 300 to 3500pa·s. The viscosity of the polyimide varnish was determined at 25℃using an E-type viscometer.

The polyimide varnish 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, a defoaming agent, an optical brightening agent, a crosslinking agent, a polymerization initiator, and a photosensitizer, as far as the required properties of the polyimide film are not impaired.

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

[ 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 as a crosslinked product obtained by crosslinking a polyimide resin with a crosslinking agent. Therefore, the polyimide film of the present invention is excellent in heat resistance, colorless transparency and chemical resistance, and further has low residual stress. The polyimide film of the present invention has suitable 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 (preferably 80 ℃ or higher, more preferably 100 ℃ or higher, still more preferably 150 ℃ or higher) at which the polyimide resin and the crosslinking agent undergo a crosslinking reaction. Examples of the method 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, and a method of forming the polyimide varnish into a film and then heating the film. By this heat treatment, the polyimide resin in the polyimide varnish is crosslinked with the crosslinking agent, and the organic solvent such as the reaction solvent and the diluting solvent contained in the polyimide varnish can be removed. If necessary, a release agent may be applied to the surface of the support in advance.

The following method is preferable as the heat treatment. That is, it is preferable that the polyimide film is produced by first evaporating the organic solvent at a temperature of 120 ℃ or lower and then drying the film at a temperature of the boiling point of the organic solvent or higher. In addition, the drying is preferably performed under a nitrogen atmosphere. The pressure of the drying atmosphere may be reduced, normal pressure or increased. By drying at a temperature of 2 stages, a film having a smooth surface and no defects can be obtained. The drying temperature in the 2 nd stage is not particularly limited, but is preferably 200 to 450 ℃, more preferably 300 to 430 ℃, and particularly preferably 350 to 400 ℃. By drying in this temperature range, the transparency and yellow index of the film become good, and good solvent resistance can be obtained.

The polyimide film of the present invention can also be produced using a polyamic acid varnish obtained by dissolving a polyamic acid and a crosslinking agent in an organic solvent.

The polyamic acid contained in the polyamic acid varnish is a precursor of the polyimide resin according to the present invention, and is a product of an addition polymerization reaction of a tetracarboxylic acid component including a compound providing the structural unit (A-1) and a diamine component including a compound providing the structural unit (B-1) and a compound providing the structural unit (B-2). The polyimide resin can be obtained by imidizing (dehydrating and ring-closing) the polyamic acid.

As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish of the present invention can be used.

In the present invention, the polyamic acid varnish may be a polyamic acid solution itself obtained by subjecting a tetracarboxylic acid component comprising a compound providing the above-mentioned structural unit (A-1) and a diamine component comprising a compound providing the above-mentioned structural unit (B-1) and a compound providing the above-mentioned structural unit (B-2) to an addition polymerization reaction in a reaction solvent, or a polyamic acid solution obtained by further adding a diluting solvent to the polyamic acid solution.

The method for producing a polyimide film using the polyamic acid varnish is not particularly limited as long as the method includes a step of crosslinking at a temperature (preferably 80 ℃ or higher, more preferably 100 ℃ or higher, still more preferably 150 ℃ or higher) at which the polyimide resin and the crosslinking agent undergo a crosslinking reaction, and a known method can be used. For example, a polyimide film can be produced by applying a polyamic acid varnish to a smooth support such as a glass plate, a metal plate, or a plastic, or by forming the varnish into a film, removing an organic solvent such as a reaction solvent or a dilution solvent contained in the varnish by heating to obtain a polyamic acid film, imidizing the polyamic acid in the polyamic acid film by heating, and further reacting a polyimide resin with a crosslinking agent to crosslink the polyimide film.

The heating temperature for drying the polyamic acid varnish to obtain a polyamic acid film is preferably 50 to 120 ℃. The heating temperature at the time of imidizing the polyamic acid by heating is preferably 200 to 400 ℃.

The imidization method is not limited to thermal imidization, and chemical imidization may be applied.

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 1 to 250 μm 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 with reference to examples. The present invention is not limited by these examples.

The solid content concentration of the varnishes and the physical properties of the films obtained in examples and comparative examples were measured by the methods shown below.

(1) Concentration of solid content

For the measurement of the solid content concentration of the varnish, the sample was heated at 320℃for 120 minutes by using a small electric furnace "MMF-1" manufactured by 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, inc.

(3) Total light transmittance, yellow Index (YI)

According to JIS K7105:1997, the total light transmittance and YI were measured by using a color/turbidity simultaneous measuring instrument "COH7700" manufactured by Nippon Denshoku industries Co.

(4) Glass transition temperature (Tg)

The sample was heated to a temperature sufficient to remove residual stress using a thermo-mechanical analysis apparatus "TMA/SS6100" manufactured by HITACHI HIGH-TECH SCIENCE co., ltd. Under conditions of a sample size of 2mm×20mm, a load of 0.1N, and a heating rate of 10 ℃/min in a tensile mode, and then cooled to room temperature. Thereafter, the elongation of the test piece was measured under the same conditions as in the treatment for removing the residual stress, and the glass transition temperature was obtained at the inflection point where the elongation was confirmed.

(5) Residual stress

A4-inch silicon wafer having a thickness of 525 μm.+ -. 25 μm, in which the "warpage" was measured in advance, was coated with a polyimide varnish or a polyamic acid varnish using a spin coater using a residual stress measuring device "FLX-2320" manufactured by KLA-Tencor Corporation, and was prebaked. Then, a silicon wafer having a polyimide film with a thickness of 8 to 15 μm after curing was produced by performing a heat curing treatment at 350 to 400℃for 30 minutes in a nitrogen atmosphere using a hot air dryer. The warpage amount of the wafer was measured by using the residual stress measuring device, and residual stress generated between the silicon wafer and the polyimide film was evaluated.

(6) Tensile modulus, tensile Strength

The tensile modulus and tensile strength were measured according to JIS K7127 using a tensile tester "Stroggraph VG-1E" manufactured by Toyo Seisakusho Co., ltd. The distance between chucks was set to 50mm, the test piece size was set to 10 mm. Times.50 mm, and the test speed was set to 20 mm/min.

(7) Solvent resistance 1 (PGMEA)

The solvent was dropped onto the polyimide film formed on the glass plate at room temperature, and the presence or absence of change in the film surface was confirmed. Propylene Glycol Monomethyl Ether Acetate (PGMEA) was used as the solvent.

The evaluation criteria for solvent resistance are as follows.

O: the film surface is unchanged.

Delta: the film had slight cracks on its surface.

X: the film surface has cracks or the film surface dissolves.

(8) Solvent resistance 2 (NMP)

Polyimide film formed on a glass plate was peeled off and immersed in N-methyl-2-pyrrolidone (NMP) at room temperature for 60 minutes. The evaluation criteria are as follows.

And (2) the following steps: the film did not dissolve and maintained shape.

X: the film dissolved and failed to maintain shape.

(9) Cleaning property

N-methyl-2-pyrrolidone and polyimide varnish were mixed to confirm whether or not they were uniformly mixed at room temperature. The cleaning performance was evaluated as follows.

And (2) the following steps: the polyimide varnish and NMP mixture were uniformly mixed.

X: the polyimide varnish and NMP mixed solution were not uniformly mixed, and a precipitate was formed.

The tetracarboxylic acid component and the diamine component used in examples and comparative examples are described below.

< Tetracarboxylic acid component >

CpODA: norbornane-2-spiro-alpha-cyclopentanone-alpha '-spiro-2' -norbornane-5, 5', 6' -tetracarboxylic dianhydride (JX energy Co., ltd.; compound represented by formula (a-1))

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

< Diamine >

TFMB:2,2' -bis (trifluoromethyl) benzidine (Compound represented by formula (b-1) of Kabushiki Kaisha)

3,5-DABA:3, 5-diaminobenzoic acid (Compound represented by formula (b-2) of Japanese pure Liang Yak Co., ltd.)

< Crosslinking agent >

1,3-PBO:1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene (manufactured by Sanguo pharmaceutical industry Co., ltd.)

< Others >

GBL: gamma-butyrolactone (Mitsubishi chemical Co., ltd.)

TEA: triethylamine (manufactured by Kanto chemical Co., ltd.)

Example 1

To a 1L five-necked round-bottomed flask equipped with a stainless steel half-moon shaped stirring blade, a nitrogen inlet tube, a condenser tube, a dean-Stark apparatus, a thermometer, and a glass end cap were charged 25.619g (0.080 mol), 3,5-DABA 3.043g (0.020 mol), and GBL 161.040g, and the mixture was stirred at 150rpm under a nitrogen atmosphere at 70℃in the system to obtain a solution.

To this solution, cpODA 38.438g (0.100 mol) and 20.130g of GBL were added together, and then 0.506g of TEA and 0.056g of triethylenediamine (manufactured by Tokyo chemical Co., ltd.) were added as imidization catalysts, 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, the rotation speed was adjusted according to the viscosity rise, and the temperature in the reaction system was kept at 190℃for 2 hours under reflux.

Thereafter, GBL was added so that the solid content became 10 mass%, the temperature in the reaction system was cooled to 120 ℃, and the mixture was stirred for about 1 hour to homogenize the mixture. Then, 0.167g of 1,3-PBO (0.25 mol% relative to 1 mol% of 3, 5-DABA) was added to 100g of the obtained varnish, and the resultant was stirred for 30 minutes to homogenize the resultant, thereby obtaining a polyimide varnish.

Then, the polyimide varnish obtained by spin coating was applied to a silicon wafer on a glass plate, and the temperature was kept at 80℃for 20 minutes by a hot plate, and then the solvent was evaporated by heating at 400℃for 30 minutes in a hot air dryer under a nitrogen atmosphere, thereby obtaining a film having a thickness of 10. Mu.m.

Example 2

A polyimide varnish was produced in the same manner as in example 1 except that the amount of TFMB was changed to 27.220g (0.085 mol) and the amount of 3,5-DABA was changed to 2.282g (0.015 mol), to obtain a polyimide varnish having a solid content of 10 mass%.

A film was produced in the same manner as in example 1 except that the drying temperature in the 2 nd stage was changed to the conditions shown in table 1 using the obtained polyimide varnish, thereby obtaining a film having a thickness of 9 μm.

Example 3

To a 1L five-necked round-bottomed flask equipped with a stainless steel half-moon shaped stirring blade, a nitrogen inlet tube, a condenser tube, a dean-Stark apparatus, a thermometer, and a glass end cap were charged 25.619g (0.080 mol), 3,5-DABA 3.043g (0.020 mol), and GBL 156.713g, and the mixture was stirred at 150rpm under a nitrogen atmosphere at 70℃in the system to obtain a solution.

To this solution, cpODA 30.750g (0.08 mol), s-BPDA 5.884g (0.02 mol) and GBL 39.178g were added together, and then, TEA 0.506g and triethylenediamine (manufactured by Tokyo chemical Co., ltd.) were added as imidization catalysts, and 0.056g were 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 components were collected, the rotation speed was adjusted according to the viscosity rise, and the temperature in the reaction system was kept at 190℃for 2 hours under reflux.

Thereafter, GBL was added so that the solid content became 10 mass%, the temperature in the reaction system was cooled to 120 ℃, and then the mixture was stirred for about 1 hour to homogenize the mixture. Then, 0.173g of 1,3-PBO (0.25 mol% based on 1 mol% of 3, 5-DABA) was charged and stirred for 30 minutes to homogenize the mixture, thereby obtaining a polyimide varnish having a solid content of 10 mass%.

Then, the polyimide varnish obtained by spin coating was applied to a silicon wafer on a glass plate, and the temperature was kept at 80℃for 30 minutes by a hot plate, and then the solvent was evaporated by heating at 350℃for 20 minutes in a hot air dryer under a nitrogen atmosphere, thereby obtaining a film having a thickness of 10. Mu.m.

Example 4

A polyimide varnish was produced in the same manner as in example 3 except that the amount of TFMB was changed to 28.822g (0.090 mol) and the amount of 3,5-DABA was changed to 1.522g (0.010 mol), so that a polyimide varnish having a solid content of 10 mass% was obtained.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 3, thereby obtaining a film having a thickness of 10. Mu.m.

Example 5

A polyimide varnish was produced in the same manner as in example 1 except that the amount of TFMB was changed to 17.933g (0.070 mol) and the amount of 3,5-DABA was changed to 3.652g (0.030 mol), so that a polyimide varnish having a solid content of 10 mass% was obtained.

Using the obtained polyimide varnish, a film was produced in the same manner as in example 3, thereby obtaining a film having a thickness of 9. Mu.m.

Comparative example 1

A polyimide varnish was produced in the same manner as in example 1, except that 1,3-PBO was not added, to obtain a polyimide varnish having a solid content of 10 mass%. Using the obtained polyimide varnish, a film was produced in the same manner as in example 1, thereby obtaining a film having a thickness of 10. Mu.m.

Comparative example 2

A polyimide varnish was produced in the same manner as in example 2, except that 1,3-PBO was not added, to obtain a polyimide varnish having a solid content of 10 mass%. Using the obtained polyimide varnish, a film was produced in the same manner as in example 1, thereby obtaining a film having a thickness of 10. Mu.m.

Comparative example 3

A polyimide varnish was produced in the same manner as in example 3, except that 1,3-PBO was not added, to obtain a polyimide varnish having a solid content of 10 mass%. Using the obtained polyimide varnish, a film was produced in the same manner as in example 1, thereby obtaining a film having a thickness of 10. Mu.m.

The obtained film was evaluated as described above. The results are shown in Table 1.

TABLE 1

As shown in table 1, the polyimide films of examples 1 to 5 were excellent in heat resistance and colorless transparency, low in residual stress, excellent in chemical resistance, and also excellent in cleaning property. On the other hand, the polyimide film of the comparative example was poor in solvent resistance.

Claims

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

The polyimide resin has a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A comprises a structural unit (A-1) derived from a compound represented by the following formula (a-1), the structural unit B comprises a structural unit (B-1) derived from a compound represented by the following formula (B-1) and a structural unit (B-2) derived from a compound represented by the following formula (B-2),

The ratio of the structural unit (B-1) in the structural unit B is 80 to 95 mol%,

The ratio of the structural unit (B-2) in the structural unit B is 5 to 20 mol%,

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, wherein m1+m2+m3+m4 is 1 or more, and when p is 2, 2X and 2m 2 to m4 are independently selected.

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

4. The polyimide resin composition according to claim 1 or 2, wherein the structural unit A further comprises a structural unit (A-2) derived from a compound represented by the following formula (a-2),

5. The polyimide resin composition according to claim 1 or 2, wherein the structural unit a further comprises a structural unit (a-3) derived from a both terminal acid anhydride-modified silicone.

6. The polyimide resin composition according to claim 1 or 2, wherein the crosslinking agent is a compound containing an aromatic ring or an aromatic heterocycle to which at least 2 oxazolyl groups are bonded.

7. The polyimide resin composition according to claim 1 or 2, wherein the crosslinking agent is a compound comprising a benzene ring to which at least 2 oxazolyl groups are bonded.

8. The polyimide resin composition according to claim 1 or 2, wherein the crosslinking agent is 1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene.

9. A polyimide varnish prepared by dissolving the polyimide resin composition according to any one of claims 1 to 8 in an organic solvent.

10. 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.