CN112940253A

CN112940253A - Polyimide precursor, resin composition, and method for producing resin film

Info

Publication number: CN112940253A
Application number: CN202110309562.4A
Authority: CN
Inventors: 米谷昌树; 清水建树; 金田隆行
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp; Asahi Chemical Industry Co Ltd
Priority date: 2015-09-24
Filing date: 2016-09-21
Publication date: 2021-06-11
Also published as: CN108026273B; TW201718714A; JP2020172652A; KR102460768B1; TWI641632B; KR20180048605A; JP7095024B2; KR102133559B1; TWI695855B; JP2024023254A; JP2022128480A; CN108026273A; KR20200085383A; JP7383764B2; JP2019070811A; WO2017051827A1; JP6444522B2; KR20220147724A; JPWO2017051827A1; TW201902992A

Abstract

The present application relates to a polyimide precursor, a resin composition, and a method for producing a resin film. Specifically, the present application relates to (a1) a polyimide precursor comprising the following general formula (1) { wherein, X is₁Represents a tetravalent group having 4 to 32 carbon atoms. R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. Structural unit L represented by the formula and the following general formula (2) { wherein, X₂Represents a tetravalent group having 4 to 32 carbon atoms. Structural unit M shown.

Description

Polyimide precursor, resin composition, and method for producing resin film

The present application is a divisional application entitled "method for producing polyimide precursor, resin composition and resin film" filed 2016, 9, 21, and having an application number of 201680054473.7.

Technical Field

The present invention relates to a polyimide precursor, a resin composition, and a method for producing a resin film, which are used for producing a substrate for a flexible device, for example.

Background

In general, for applications requiring high heat resistance, a polyimide resin film is used as a resin film. A conventional polyimide resin is a highly heat-resistant resin produced by polymerizing an aromatic carboxylic dianhydride with an aromatic diamine solution to produce a polyimide precursor, and then thermally imidizing the polyimide precursor at a high temperature or chemically imidizing the polyimide precursor using a catalyst.

The polyimide resin is an insoluble and infusible super heat-resistant resin, and has excellent properties such as thermal oxidation resistance, heat resistance, radiation resistance, low temperature resistance, and chemical resistance. Therefore, polyimide resins are used in a wide range of fields including electronic materials. Examples of applications of polyimide resins in the field of electronic materials include insulating coating agents, insulating films, protective films for semiconductors, and electrode protective films for TFT-LCDs. Recently, studies have been made to replace glass substrates, which have been conventionally used in the field of display materials, with colorless transparent flexible substrates, which are lightweight and flexible.

In the production of a polyimide resin film as a flexible substrate, a composition containing a polyimide precursor is applied to an appropriate support to form a coating film, and then the coating film is heat-treated to imidize the coating film, thereby obtaining a polyimide resin film. As the support, for example, glass, silicon nitride, silicon oxide, metal, or the like is used. In the production of a laminate having a polyimide film on such a support, a heat treatment at a high temperature of 250 ℃ or higher is required for drying and imidizing the polyimide precursor. This heat treatment causes a residual stress in the laminate, and causes serious problems such as warpage and peeling. This is because the linear thermal expansion coefficient of polyimide is larger than that of the material constituting the support.

The polyimide material having a small thermal expansion coefficient is most commonly known as a polyimide formed from 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and p-phenylenediamine. It is reported that: this polyimide film exhibits a very low linear thermal expansion coefficient, although it also depends on the film thickness and the production conditions (non-patent document 1).

In addition, it is reported that: polyimide having an ester structure in a molecular chain has appropriate linearity and rigidity, and thus exhibits a low linear thermal expansion coefficient (patent document 1).

However, conventional polyimide resins, including the polyimides described in the above documents, are colored brown or yellow due to a high aromatic ring density, and therefore have low light transmittance in the visible light region, and thus are difficult to use in fields requiring transparency. For example, the polyimide of non-patent document 1 obtained from 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride and p-phenylenediamine has a yellow index (YI value) of 40 or more at a film thickness of 10 μm, and is insufficient in transparency.

Regarding the yellow index of the thin film, for example, polyimide using a monomer having a fluorine atom is known to exhibit an extremely low yellow index (patent document 2).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4627297

Patent document 2: japanese Kohyo publication No. 2010-538103

Patent document 3: japanese patent No. 3079867

Non-patent document

Non-patent document 1: new polyimide Nippon polyimide research institute (NTS) coding

Disclosure of Invention

Problems to be solved by the invention

Therefore, in order to use a polyimide resin as a colorless transparent flexible substrate, excellent mechanical properties such as elongation and breaking strength are required in addition to transparency. In particular, recently, a device type associated with TFTs is LTPS (low temperature polysilicon TFT), and a thin film exhibiting the above properties even in a more severe thermal history than ever before is desired.

However, the physical properties of known transparent polyimides are insufficient for use as heat-resistant colorless transparent substrates for display.

Further, the present inventors have confirmed that: the polyimide resin described in patent document 1 exhibits a low linear thermal expansion coefficient, but the polyimide resin film after peeling has a large yellow index (YI value), and has problems of high residual stress, low elongation, and low breaking strength.

Regarding the yellowness index, it is known that: the polyimide film described in patent document 2 exhibits a low yellowness index in a temperature range of about 300 ℃, but the yellowness index (YI value) is significantly deteriorated in a high temperature range of 400 ℃ or higher.

Further, as a polyimide having a reduced coefficient of linear expansion, a polyimide comprising 4,4 '-diaminodiphenyl ether and 4, 4' -diaminodiphenyl ester is disclosed (patent document 3).

However, the present inventors confirmed that: the polyimide resin described in patent document 3 is very brittle when used as a flexible substrate, and has room for improvement in yellow index at high temperatures.

The present invention has been made in view of the above-described problems. Accordingly, an object of the present invention is to provide a polyimide resin film having a low residual stress, a small warpage, a small yellowness index (YI value), and a high elongation, and a method for producing the same.

Means for solving the problems

The present invention is as follows.

[1] A (a1) polyimide precursor characterized by comprising a structural unit L represented by the following general formula (1) and a structural unit M represented by the following general formula (2) in a proportion of 1/99 or less (the number of moles of the structural unit L/the number of moles of the structural unit M) or less than 99/1.

{ in formula (II), X₁Represents a tetravalent group having 4 to 32 carbon atoms. R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. }

{ in formula (II), X₂Represents a tetravalent group having 4 to 32 carbon atoms. Y is at least 1 selected from the group consisting of the following general formulae (3), (4) and (5) }

{ formula (II) wherein R₄～R₁₁Each independentlyRepresents a C1-20 monovalent organic group. d to k are integers of 0 to 4. }

[2] The polyimide precursor according to [1], wherein n in the general formula (1) is 0.

[3] The polyimide precursor according to [1] or [2], wherein Y in the general formula (2) is a general formula (3).

[4] The polyimide precursor according to [1] or [2], wherein Y in the general formula (2) is a general formula (4).

[5] The polyimide precursor according to [1] or [2], wherein Y in the general formula (2) is a general formula (5).

[6] A polyimide precursor (a2) characterized by having a structural unit represented by the following general formula (10) and having a weight-average molecular weight of 30000 or more and 300000 or less,

{ in formula (II), X₃Represents a tetravalent group derived from at least 1 selected from the group consisting of 4,4 '-Oxybisphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA), and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ). R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. }

[7] The polyimide precursor according to [6], wherein the content of molecules having a weight average molecular weight of less than 1000 in the polyimide precursor (a2) is less than 5% by mass.

[8] The polyimide precursor according to [6] or [7], wherein n in the general formula (10) is 0.

[9]According to [1]～[5]The polyimide precursor of any one of the above, wherein X1 and X are as defined above₂Is a tetravalent organic group derived from at least 1 selected from the group consisting of pyromellitic dianhydride (PMDA), 4 '-Oxydiphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA), and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ).

[10] A resin composition comprising the polyimide precursor according to any one of [1] to [9] and (b) an organic solvent.

[11] The resin composition according to [10], further comprising at least 1 selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.

[12] A polyimide is characterized by having a structural unit represented by the following general formula (11).

{ in formula (II), X₁、X₂Represents a tetravalent group having 4 to 32 carbon atoms. R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. Y is at least 1 selected from the group consisting of the following general formulae (3), (4) and (5). l and m independently represent an integer of 1 or more, and satisfy 0.01. ltoreq. l/(l + m). ltoreq.0.99. }

{ formula (II) wherein R₄～R₁₁Each independently represents a C1-20 monovalent organic group. d to k are integers of 0 to 4. }

[13] A polyimide having a structural unit represented by the following general formula (12) and having an elongation of 15% or more.

{ in formula (II), X₃Represents a tetravalent group derived from at least 1 selected from the group consisting of 4,4 '-Oxybisphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA), and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ). R₁、R₂、R₃Each independently represents a carbon number of 1 to 20A monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. }

[14] A method for manufacturing a resin film, comprising the steps of:

a step of applying the resin composition according to [10] or [11] onto a surface of a support to form a coating film;

heating the support and the coating film to imidize a polyimide precursor contained in the coating film to form a polyimide resin film; and

and a step of peeling the polyimide resin film from the support.

[15] The method of producing a resin film according to item [14], wherein a step of irradiating the polyimide resin film with a laser beam from the support body side is performed before a step of peeling the polyimide resin film from the support body.

[16] A method for manufacturing a laminate, comprising the steps of:

a step of applying the resin composition according to [10] or [11] onto a surface of a support to form a coating film; and

and a step of heating the support and the coating film to imidize the polyimide precursor contained in the coating film, thereby forming a polyimide resin film.

[17] A method for manufacturing a display substrate, comprising:

heating the support and the coating film to imidize a polyimide precursor contained in the coating film to form a polyimide resin film;

forming an element or a circuit on the polyimide resin film; and

and a step of peeling the polyimide resin film on which the element or the circuit is formed from the support.

[18] A polyimide film for display, characterized by comprising a polyimide represented by the following general formula (12).

{ in formula (II), X₃Is at least 1 selected from the group consisting of 4,4 '-Oxydiphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA) and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ), R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. }

[19] A laminate, comprising: a polyimide thin film layer containing a polyimide represented by the following general formula (13), and a low-temperature polysilicon TFT layer.

[20] A polyimide film characterized by having a yellow index of 20 or less when the film is 10 μm thick, an absorbance at 308nm of 0.6 to 2.0 when the film is 1 μm thick, and an elongation of 15% or more after heating at 400 ℃ or more.

[21] A resin composition, comprising:

(a) a polyimide precursor represented by the following general formula (1),

(b) An organic solvent, and

at least 1 selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.

ADVANTAGEOUS EFFECTS OF INVENTION

The polyimide film obtained from the polyimide precursor and the resin composition of the present invention has low residual stress, less warpage, a small yellow index (YI value), and a high elongation.

Drawings

Fig. 1 is a diagram showing the structure of the organic EL substrate produced in the example and the comparative example.

Detailed Description

Hereinafter, exemplary embodiments of the present invention (hereinafter, abbreviated as "embodiments") will be described in detail. The present invention is not limited to the following embodiments, and can be implemented in various modifications within the scope of the gist thereof. The characteristic values described in the present disclosure are values measured by the methods described in [ examples ] or equivalent methods that can be considered by those skilled in the art, unless otherwise specified.

< resin composition >

One embodiment of the present invention provides a resin composition containing (a) a polyimide precursor and (b) an organic solvent.

Hereinafter, each component will be described in order.

[ polyimide precursor ]

The polyimide precursor of the first embodiment of the present invention is a (a1) polyimide precursor, characterized by comprising a structural unit L represented by the following general formula (1) and a structural unit M represented by the following general formula (2) at 1/99 ≦ (the number of moles of the structural unit L/the number of moles of the structural unit M) ≦ 99/1.

The polyimide precursor of the first embodiment of the present embodiment has low residual stress, less warpage, a small yellowness index (YI value), and a high elongation when formed into a polyimide film. In addition, the polyimide precursor of the first embodiment of the present embodiment has a small yellow index (YI value) in a high temperature region when formed into a polyimide film.

Here, R₁～R₃Each independently represents a monovalent organic group having 1 to 20 carbon atoms, and is not limited. Examples of such an organic group include an alkyl group such as a methyl group, an ethyl group, and a propyl group, a halogen-containing group such as a trifluoromethyl group, and an alkoxy group such as a methoxy group and an ethoxy group. Among them, methyl is preferable from the viewpoint of YI in the high temperature region.

Here, a, b, c, d are integers of 0 to 4, and are not limited. Among them, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.

Here, n is 0 or 1. Among them, 0 is preferable from the viewpoint of YI in the high temperature region.

The lower limit of the molar ratio of the structural unit L to the structural unit M (the number of moles of the structural unit L/the number of moles of the structural unit M) may be 5/95, 10/90, 20/80, 30/70, 40/60. The upper limit of the molar ratio of the structural unit L to the structural unit M (the number of moles of the structural unit L/the number of moles of the structural unit M) may be 95/5, 90/10, 80/20, 70/30, 60/40.

X₁、X₂Each independently is a tetravalent group having 4 to 32 carbon atoms, and may be the same or different. Examples of the tetravalent organic group derived from the tetracarboxylic dianhydride described below are shown.

Specific examples of the tetracarboxylic dianhydride include compounds selected from aromatic tetracarboxylic dianhydrides having 8 to 36 carbon atoms, aliphatic tetracarboxylic dianhydrides having 6 to 36 carbon atoms, and alicyclic tetracarboxylic dianhydrides having 6 to 36 carbon atoms. Among them, from the viewpoint of yellow index in a high temperature region, an aromatic tetracarboxylic dianhydride having 8 to 36 carbon atoms is preferable. The carbon number as used herein also includes the number of carbons contained in the carboxyl group.

More specifically, examples of the aromatic tetracarboxylic acid dianhydride having 8 to 36 carbon atoms include 4,4 ' - (hexafluoroisopropylidene) diphthalic anhydride (hereinafter also referred to as 6FDA), 5- (2, 5-dioxotetrahydro-3-furanyl) -3-methyl-cyclohexene-1, 2-dicarboxylic anhydride, pyromellitic dianhydride (hereinafter also referred to as PMDA), 1,2,3, 4-benzenetetracarboxylic dianhydride, 3,3 ', 4,4 ' -benzophenonetetracarboxylic dianhydride, 2 ', 3,3 ' -benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4 ' -biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA), 3,3 ', 4,4 ' -diphenylsulfonetetracarboxylic dianhydride, 2 ', 3,3 ' -biphenyltetracarboxylic dianhydride, and mixtures thereof, Methylene-4, 4 '-Biphthalic dianhydride, 1-ethylene-4, 4' -Biphthalic dianhydride, 2-propylene-4, 4 '-Biphthalic dianhydride, 1, 2-ethylene-4, 4' -Biphthalic dianhydride, 1, 3-trimethylene-4, 4 '-Biphthalic dianhydride, 1, 4-tetramethylene-4, 4' -Biphthalic dianhydride, 1, 5-pentamethylene-4, 4 '-Biphthalic dianhydride, 4' -oxydiphthalic dianhydride (hereinafter also referred to as ODPA), p-phenylene bis (trimellitic acid monoester anhydride) (hereinafter also referred to as TAHQ), thio-4, 4 '-Biphthalic dianhydride, Diphthalic acid dianhydride, 1, 2-propylene-4, 4' -Biphthalic acid dianhydride, 2, sulfonyl-4, 4' -biphthalic dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) benzene dianhydride, 1, 3-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 4-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 3-bis [2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, 1, 4-bis [2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, bis [3- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, bis [4- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, 2-bis [3- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, 1, 3-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 3-bis (3, 4-dicarboxyphenoxy) phenyl) benzene dianhydride, 1, 3-bis (2-, 2, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, bis (3, 4-dicarboxyphenoxy) dimethylsilane dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) -1,1,3, 3-tetramethyldisiloxane dianhydride, 2,3,6, 7-naphthalenetetracarboxylic dianhydride, 1,4,5, 8-naphthalenetetracarboxylic dianhydride, 1,2,5, 6-naphthalenetetracarboxylic dianhydride, 3,4,9, 10-perylenetetracarboxylic dianhydride, 2,3,6, 7-anthracenetetracarboxylic dianhydride, 1,2,7, 8-phenanthrenetetracarboxylic dianhydride and the like.

Examples of the aliphatic tetracarboxylic dianhydride having 6 to 50 carbon atoms include ethylene tetracarboxylic dianhydride, 1,2,3, 4-butane tetracarboxylic dianhydride, and the like;

examples of the alicyclic tetracarboxylic dianhydride having 6 to 36 carbon atoms include 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1, 2,3, 4-tetracarboxylic dianhydride, cyclohexane-1, 2,4, 5-tetracarboxylic dianhydride (hereinafter referred to as CHDA), 3 ', 4, 4' -dicyclohexyltetracarboxylic dianhydride, carbonyl-4, 4 '-bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, methylene-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 1, 2-ethylene-4, 4 '-bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 1-ethylene-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 2, 2-propylene-4, 4 '-bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, oxy-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, thio-4, 4 '-bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, sulfonyl-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, bicyclo [2,2,2] oct-7-ene-2, 3,5, 6-tetracarboxylic acid dianhydride, rel- [1S,5R,6R ] -3-oxabicyclo [3,2,1] octane-2, 4-dione-6-spiro-3 '- (tetrahydrofuran-2', 5' -dione), 4- (2, 5-dioxotetrahydrofuran-3-yl) -1,2,3, 4-tetrahydronaphthalene-1, 2-dicarboxylic anhydride, ethylene glycol-bis- (3, 4-dicarboxylic anhydride phenyl) ether, and the like.

From the viewpoint of the balance between CTE, chemical resistance, Tg, and yellow index in the high temperature region, PMDA, BPDA, TAHQ, and ODPA are preferable, and BPDA and TAHQ are more preferable.

The polyimide precursor according to the embodiment may be a polyamide-imide precursor prepared by using a dicarboxylic acid in addition to the tetracarboxylic dianhydride, within a range not impairing the performance of the polyimide precursor. By using such a precursor, various properties such as an increase in mechanical elongation, an increase in glass transition temperature, and a decrease in yellow index can be adjusted for the obtained film. Examples of such dicarboxylic acids include dicarboxylic acids having an aromatic ring and alicyclic dicarboxylic acids. Particularly preferably at least one compound selected from the group consisting of an aromatic dicarboxylic acid having 8 to 36 carbon atoms and an alicyclic dicarboxylic acid having 6 to 34 carbon atoms. The carbon number as referred to herein also includes the number of carbons contained in the carboxyl group.

Among them, dicarboxylic acids having an aromatic ring are preferable.

Specific examples thereof include isophthalic acid, terephthalic acid, 4 '-biphenyldicarboxylic acid, 3' -biphenyldicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 2, 3-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, 4 '-sulfonylbisbenzoic acid, 3' -sulfonylbisbenzoic acid, 4 '-oxybisbenzoic acid, 3' -oxybisbenzoic acid, 2-bis (4-carboxyphenyl) propane, 2-bis (3-carboxyphenyl) propane, 2 '-dimethyl-4, 4' -biphenyldicarboxylic acid, and the like, 3,3 ' -dimethyl-4, 4 ' -biphenyldicarboxylic acid, 2 ' -dimethyl-3, 3 ' -biphenyldicarboxylic acid, 9-bis (4- (4-carboxyphenoxy) phenyl) fluorene, 9-bis (4- (3-carboxyphenoxy) phenyl) fluorene, 4 ' -bis (4-carboxyphenoxy) biphenyl, 4 ' -bis (3-carboxyphenoxy) biphenyl, 3,4 ' -bis (4-carboxyphenoxy) biphenyl, 3,4 ' -bis (3-carboxyphenoxy) biphenyl, 3 ' -bis (4-carboxyphenoxy) biphenyl, 3 ' -bis (3-carboxyphenoxy) biphenyl, 4 ' -bis (4-carboxyphenoxy) -p-terphenyl, p-terphenyl, 4,4 '-bis (4-carboxyphenoxy) -m-terphenyl, 3, 4' -bis (4-carboxyphenoxy) -p-terphenyl, 3 '-bis (4-carboxyphenoxy) -p-terphenyl, 3, 4' -bis (4-carboxyphenoxy) -m-terphenyl, 3 '-bis (4-carboxyphenoxy) -m-terphenyl, 4' -bis (3-carboxyphenoxy) -p-terphenyl, 4 '-bis (3-carboxyphenoxy) -m-terphenyl, 3, 4' -bis (3-carboxyphenoxy) -p-terphenyl, 3 '-bis (3-carboxyphenoxy) -p-terphenyl, 3, 4' -bis (3-carboxyphenoxy) -m-terphenyl, p-n-bis (3-carboxyphenoxy) -p-terphenyl, 3,3 '-bis (3-carboxyphenoxy) -m-terphenyl, 1-cyclobutanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1, 2-cyclohexanedicarboxylic acid, 4' -benzophenonedicarboxylic acid, 1, 3-phenylenediacetic acid, 1, 4-phenylenediacetic acid, and the like; and

5-aminoisophthalic acid derivatives described in International publication No. 2005/068535 pamphlet, and the like. In practice, when these dicarboxylic acids are copolymerized in a polymer, they may be used in the form of an acid chloride derived from thionyl chloride or the like, an active ester, or the like.

The weight average molecular weight (Mw) of the polyimide precursor in the present embodiment is preferably 10000 to 300000, and particularly preferably 30000 to 200000. When the weight average molecular weight is more than 10000, mechanical properties such as elongation and breaking strength are excellent, residual stress is low, and YI is low. When the weight average molecular weight is less than 300000, the weight average molecular weight can be easily controlled during synthesis of the polyamic acid, and a resin composition having an appropriate viscosity can be obtained, and the coatability of the resin composition is improved. In the present disclosure, the weight average molecular weight is a value determined as a standard polystyrene equivalent value using gel permeation chromatography (hereinafter referred to as GPC).

In the polyimide precursor of the present embodiment, the content of molecules having a molecular weight of less than 1000 is preferably less than 5% by mass, more preferably less than 1% by mass, based on the total amount of the polyimide precursor. A polyimide film formed from a resin composition obtained using such a polyimide precursor is preferable from the viewpoint of low residual stress and low haze of an inorganic film formed on the polyimide film.

The content of molecules having a molecular weight of less than 1000 relative to the total amount of the polyimide precursor can be calculated from the peak area obtained by GPC measurement using a solution in which the polyimide precursor is dissolved.

Examples of the diamine used as the structural unit represented by the general formula (1) in the present embodiment include diamines represented by the following general formula (6).

(in the formula, R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. )

As R₁、R₂Examples thereof include alkyl groups such as methyl, ethyl and propyl, halogen-containing groups such as trifluoromethyl, and alkoxy groups such as methoxy and ethoxy. Among them, methyl is preferable from the viewpoint of YI in the high temperature region.

Here, a and b are not limited as long as they are integers of 0 to 4. Among them, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.

More specifically, when n is 0, 4-aminophenyl-4-aminobenzoate (APAB), 2-methyl-4-aminophenyl-4-aminobenzoate (ATAB), 4-aminophenyl-3-aminobenzoate (4,3-APAB), and the like can be exemplified.

When n is 1, for example, [4- (4-aminobenzoyl) oxyphenyl ] 4-aminobenzoate and the like can be illustrated.

Examples of the diamine used as the structural unit represented by the general formula (3) in the present embodiment include diamines represented by the following general formula (7).

(in the formula, R₄、R₅Each independently represents a C1-20 monovalent organic group. d. e is an integer of 0 to 4. )

Here, R₄、R₅Each independently represents a monovalent organic group having 1 to 20 carbon atoms, and is not limited. Examples of such an organic group include an alkyl group such as a methyl group, an ethyl group, and a propyl group, a halogen-containing group such as a trifluoromethyl group, and an alkoxy group such as a methoxy group and an ethoxy group. Among them, methyl is preferable from the viewpoint of YI in the high temperature region.

Here, c and d are not limited as long as they are integers of 0 to 4. Among them, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.

More specifically, 4 '-diaminodiphenyl sulfone and 3, 3' -diaminodiphenyl sulfone are exemplified.

Examples of the diamine used as the structural unit represented by the general formula (4) in the present embodiment include diamines represented by the following general formula (8).

Here, R₆And R₇Each independently represents a monovalent organic group having 1 to 20 carbon atoms, and is not limited. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Among them, methyl is preferable from the viewpoint of YI in the high temperature region.

R₈And R₉Each independently may be a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, or a halogen atom, and is not limited. Examples of the organic group include alkyl groups such as methyl, ethyl, and propyl; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.

f. g, h, and i are each independently an integer of 0 to 4, and are not limited. Among them, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.

Examples of Z include a single bond, methylene, ethylene, ether, and ketone. Among them, a single bond is more preferable from the viewpoint of YI in the high temperature region.

More specifically, 9-bis (aminophenyl) fluorene, 9-bis (4-amino-3-methylphenyl) fluorene, 9-bis (4-amino-3-fluorophenyl) fluorene, 9-bis (4-hydroxy-3-aminophenyl) fluorene, 9-bis [4- (4-aminophenoxy) phenyl ] fluorene, and the like are exemplified, and 1 or more selected from them are preferably used.

Examples of the diamine used as the structural unit represented by the general formula (5) in the present embodiment include diamines represented by the following general formula (9).

Here, R₁₀And R₁₁Each independently represents a monovalent organic group having 1 to 20 carbon atoms, and is not limited. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Among them, methyl is preferable from the viewpoint of YI in the high temperature region.

J and k are each independently an integer of 0 to 4, and are not limited. Among them, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.

More specifically, 2' -bis (trifluoromethyl) benzidine and the like can be exemplified.

The polyimide film formed from the polyimide precursor of the first embodiment of the present invention has low residual stress, less warpage, a small yellowness index (YI value) in a high temperature region, and a high elongation.

As a second aspect of the present embodiment, there is provided (a2) a polyimide precursor having a structural unit represented by the following general formula (10) and having a weight average molecular weight of 30000 or more and 300000 or less.

{ in formula (II), X₃Represents a tetravalent group derived from at least 1 selected from 4,4 '-Oxybisphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA), and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ). R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a,b and c are integers of 0-4. }

Here, X₃The tetravalent organic group derived from at least 1 selected from ODPA, BPDA and TAHQ may be used without limitation, and BPDA and TAHQ are preferable from the viewpoint of CTE and Tg.

As the diamine used for the structure represented by the general formula (10), the diamine used in the general formula (6) can be used.

The polyimide precursor in the second embodiment has a weight average molecular weight (Mw) of 30000 to 300000. When the weight average molecular weight is more than 30000, mechanical properties such as elongation and breaking strength are excellent, residual stress is low, and YI is low. When the weight average molecular weight is less than 300000, the weight average molecular weight can be easily controlled during synthesis of the polyamic acid, and a resin composition having an appropriate viscosity can be obtained, and the coatability of the resin composition is improved. Among them, the weight average molecular weight (Mw) is more preferably 35000 or more and 250000 or less, and particularly preferably 40000 or more and 230000 or less.

In the polyimide precursor according to the second embodiment of the present invention, the content of molecules having a molecular weight of less than 1000 is preferably less than 5% by mass, more preferably less than 1% by mass, based on the total amount of the polyimide precursor. A polyimide film formed from a resin composition obtained using such a polyimide precursor is preferable from the viewpoint of low residual stress and low haze of an inorganic film formed on the polyimide film.

The content of molecules having a molecular weight of less than 1000 relative to the total amount of the polyimide precursor can be calculated from the peak area obtained by GPC measurement using a solution in which the polyimide precursor is dissolved. .

The polyimide precursor of the second embodiment of the present embodiment is excellent in storage stability and coatability. The polyimide film formed from the polyimide precursor of the second embodiment of the present invention has low residual stress, less warpage, a small yellowness index (YI value), high elongation, and high breaking strength.

In the polyimide precursors according to the first and second embodiments, other diamines may be used in addition to the diamines represented by the general formulae (6) to (9) described above, in a range in which elongation, strength, stress, yellowness index, and the like are not impaired.

Examples of the other diamines include p-phenylenediamine, m-phenylenediamine, 4 ' -diaminodiphenyl sulfide, 3 ' -diaminodiphenyl sulfide, 4 ' -diaminobiphenyl, 3 ' -diaminobiphenyl, 4 ' -diaminobenzophenone, 3 ' -diaminobenzophenone, 4 ' -diaminodiphenylmethane, 3 ' -diaminodiphenylmethane, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene, 4-diaminodiphenyl sulfide, 3,4 ' -diaminodiphenyl sulfide, 3,4 ' -diaminodiphenyl, 3 ' -diaminodiphenyl, 1, 4-bis (4-aminopheno, Bis [4- (4-aminophenoxy) phenyl ] sulfone, 4-bis (4-aminophenoxy) biphenyl, 4-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) phenyl ] ether, 1, 4-bis (4-aminophenyl) benzene, 1, 3-bis (4-aminophenyl) benzene, 9, 10-bis (4-aminophenyl) anthracene, 2-bis (4-aminophenyl) propane, 2-bis (4-aminophenyl) hexafluoropropane, 2-bis [4- (4-aminophenoxy) phenyl) propane, 2-bis [4- (4-aminophenoxy) phenyl) hexafluoropropane, 1, 4-bis (3-aminopropyldimethylsilyl) benzene, etc., and preferably 1 or more selected from them are used.

The content of the other diamine in the total diamine is preferably 20 mol% or less, and particularly preferably 10 mol% or less.

[ production of polyimide precursor ]

The polyimide precursor (polyamic acid) of the present invention can be synthesized by subjecting tetracarboxylic dianhydride to polycondensation reaction with a diamine (for example, APAB) used for the structural unit represented by the above general formula (1) and a diamine (for example, 4' -DAS) used for the structural unit represented by the above general formula (2). The reaction is preferably carried out in a suitable solvent. Specifically, examples thereof include: a method in which APAB and 4, 4' -DAS are dissolved in a predetermined amount in a solvent, and then a predetermined amount of tetracarboxylic dianhydride is added to the resulting diamine solution, followed by stirring.

In the diamine component, the molar ratio of the diamine used as the structural unit represented by the general formula (1) to the diamine used as the structural unit represented by the general formula (2) is not limited to 99/1 to 1/99. In the diamine component, when the amount of the diamine used in the structural unit represented by the general formula (2) is 1 mol% or more, the yellow index tends to be good, and when the amount of the diamine used in the structural unit represented by the general formula (1) is 1 mol% or more, the warping tends to be good after the inorganic film is formed on the obtained polyimide film. The molar ratio of the diamine used in the structural unit represented by the general formula (1) to the diamine used in the structural unit represented by the general formula (2) is preferably 95/5 to 50/50, and more preferably 90/10 to 50/50. The molar ratio of the diamine used in the structural unit represented by the general formula (1) to the diamine used in the structural unit represented by the general formula (2) may be 80/20 to 50/50, and may be 70/30 to 50/50. The molar ratio of the diamine used in the structural unit represented by the general formula (1) is preferably not less than the molar ratio of the diamine used in the structural unit represented by the general formula (2).

The polyimide precursor of the second embodiment of the present embodiment can be synthesized by subjecting a tetracarboxylic dianhydride (e.g., TAHQ) and a diamine (e.g., APAB) used for the structural unit represented by the general formula (6) to a polycondensation reaction. The reaction is preferably carried out in a suitable solvent. Specifically, examples thereof include: a method in which a predetermined amount of APAB is dissolved in a solvent, and then a predetermined amount of TAHQ is added to the resulting diamine solution, followed by stirring.

In the synthesis of the polyimide precursor, the ratio (molar ratio) of the tetracarboxylic dianhydride component to the diamine component is preferably a tetracarboxylic dianhydride from the viewpoint of controlling the linear thermal expansion coefficient, residual stress, elongation, and yellowness index (hereinafter also referred to as YI) of the obtained resin film within desired ranges: diamine 100: 90-100: 110 (0.90 to 1.10 parts by mole of diamine per 1 part by mole of tetracarboxylic dianhydride), more preferably 100: 95-100: 105 (0.95 to 1.05 parts by mole of diamine based on 1 part by mole of acid dianhydride).

In the present embodiment, when a polyamic acid which is a preferable polyimide precursor is synthesized, the molecular weight can be controlled by adjusting the ratio of the tetracarboxylic dianhydride component to the diamine component and adding a capping agent. The closer the ratio of the acid dianhydride component to the diamine component is to 1: 1. and the smaller the amount of the end-capping agent used, the more the molecular weight of the polyamic acid can be increased.

As the tetracarboxylic dianhydride component and the diamine component, high-purity products are recommended. The purity is preferably 98% by mass or more, more preferably 99% by mass or more, and still more preferably 99.5% by mass or more, respectively. When a plurality of acid dianhydride components or diamine components are used in combination, it is sufficient that the acid dianhydride component or diamine component as a whole has the above-mentioned purity, and it is preferable that all the types of acid dianhydride components and diamine components used have the above-mentioned purity, respectively.

The solvent for the reaction is not particularly limited as long as it can dissolve the tetracarboxylic dianhydride component and the diamine component, and the resulting polyamic acid to obtain a polymer having a high molecular weight. Specific examples of such a solvent include aprotic solvents, phenol solvents, ether solvents, glycol solvents, and the like. As specific examples thereof, there can be mentioned, respectively,

examples of the aprotic solvent include N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N-methylcaprolactam, 1, 3-dimethylimidazolidinone, tetramethylurea, and compounds represented by the following general formula (13):

R₁₂エクアミド M100 (trade name: manufactured by Shikino Co., Ltd.) represented by the formula ═ methyl group, and R₁₂Amide solvents such as エクアミド B100 (trade name: manufactured by mitsunrising corporation) represented by n-butyl;

lactone solvents such as γ -butyrolactone and γ -valerolactone;

phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphine triamide;

sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane;

ketone solvents such as cyclohexanone and methylcyclohexanone;

tertiary amine solvents such as picoline and pyridine;

ester solvents such as acetic acid (2-methoxy-1-methylethyl ester);

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, 3, 5-xylenol, and the like;

examples of the ether and glycol solvents 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.

The boiling point of the solvent used for the synthesis of the polyamic acid under normal pressure is preferably 60 to 300 ℃, more preferably 140 to 280 ℃, and particularly preferably 170 to 270 ℃. When the boiling point of the solvent is higher than 300 ℃, the drying process takes a long time. On the other hand, when the boiling point of the solvent is less than 60 ℃, roughness may be generated on the surface of the resin film in the drying step, or air bubbles may be mixed into the resin film, and a uniform film may not be obtained.

In this way, it is preferable to use a solvent having a boiling point of preferably 170 to 270 ℃ and a vapor pressure of 250Pa or less at 20 ℃ from the viewpoints of solubility and edge shrinkage at the time of coating. More specifically, 1 or more selected from the group consisting of N-methyl-2-pyrrolidone, γ -butyrolactone, and the compound represented by the general formula (11) is preferably used.

The moisture content in the solvent is preferably 3000 ppm by mass or less.

These solvents may be used alone or in combination of 2 or more.

In the polyimide precursor (a) in the present embodiment, the content of molecules having a molecular weight of less than 1000 is preferably less than 5% by mass.

The presence of molecules having a molecular weight of less than 1000 in the polyimide precursor (a) is considered to be related to the water content of the solvent used in the synthesis. That is, it is considered that a part of the acid anhydride groups of the acid dianhydride monomer are hydrolyzed to become carboxyl groups, and the carboxyl groups remain in a low molecular weight state without increasing the molecular weight. Therefore, it is preferable that the amount of water in the solvent used in the above polymerization reaction is as small as possible. The water content of the solvent is preferably 3000 ppm by mass or less, more preferably 1000 ppm by mass or less.

The water content of the solvent is considered to be related to the grade of the solvent used (e.g., a dehydration grade, a general-purpose grade), a solvent container (e.g., a bottle, an 18L tank, or a cartridge), a storage state of the solvent (e.g., presence or absence of rare gas encapsulation), a time from the unsealing to the use (e.g., use immediately after the unsealing, use after a certain time has elapsed), and the like. Further, it is considered that the substitution of the rare gas in the reactor before the synthesis, the presence or absence of the circulation of the rare gas during the synthesis, and the like are also involved. Therefore, it is recommended to use a high-purity product as a raw material and a solvent with a small amount of water in the synthesis of the polyimide precursor (a), and to take measures so as not to mix moisture from the environment into the system before and during the reaction.

When the monomer components are dissolved in the solvent, heating may be performed as necessary.

(a) The reaction temperature in the synthesis of the polyimide precursor is preferably 0 to 120 ℃, more preferably 40 to 100 ℃, and still more preferably 60 to 100 ℃. By carrying out the polymerization reaction at this temperature, a polyimide precursor having a high degree of polymerization can be obtained. The polymerization time is preferably 1 to 100 hours, more preferably 2 to 10 hours. By setting the polymerization time to 1 hour or more, a polyimide precursor having a uniform polymerization degree can be obtained, and by setting the polymerization time to 100 hours or less, a polyimide precursor having a high polymerization degree can be obtained.

In a preferred embodiment of the present embodiment, the polyimide precursor (a1) and the polyimide precursor (a2) have the following characteristics.

The resin has a yellow index of 30 or less at a film thickness of 10 μm, which is obtained by applying a solution obtained by dissolving the polyimide precursor (a) in a solvent (e.g., N-methyl-2-pyrrolidone) to the surface of a support, and then heating the solution at 300 to 550 ℃ (e.g., 430 ℃) in a nitrogen atmosphere (e.g., in nitrogen having an oxygen concentration of 2000ppm or less) (e.g., for 1 hour).

The polyimide precursor is imidized by applying a solution obtained by dissolving the polyimide precursor (a) in a solvent (e.g., N-methyl-2-pyrrolidone) to the surface of a support, and then heating the solution at 300 to 550 ℃ (e.g., 430 ℃) in a nitrogen atmosphere (e.g., in nitrogen having an oxygen concentration of 2000ppm or less) (e.g., for 1 hour), whereby the residual stress of the resin obtained is 25MPa or less.

The polyimide precursor in the present embodiment may further contain a polyimide precursor having a structure represented by the following general formula (14) as needed within a range that does not impair the desired performance of the present invention.

{ general formula (14), wherein plural R's are present₁₃Each independently a hydrogen atom, a monovalent aliphatic hydrocarbon having 1 to 20 carbon atoms, or a monovalent aromatic group,

X₄a tetravalent organic group having 4 to 32 carbon atoms,

y is a C4-32 divalent organic group. Wherein the content of the first and second substances,

structural units corresponding to the above general formula (1) and the above general formula (6) are not included. }

In the general formula (14), R₁₃Preferably a hydrogen atom. In addition, X₃The tetravalent aromatic group is preferable from the viewpoints of heat resistance, a decrease in YI value, and total light transmittance. In addition, the decrease in Y from the heat resistance, YI value and the totalThe divalent aromatic group or alicyclic group is preferable from the viewpoint of light transmittance.

The mass ratio of the polyimide precursor having a structural unit represented by the general formula (14) in the polyimide precursor (a) in the present embodiment is preferably 80 mass% or less with respect to the whole polyimide precursor (a), and more preferably 70 mass% or less from the viewpoint of reduction in the YI value and the oxygen dependence of the total light transmittance.

In a preferred embodiment of the present embodiment, a part of the (a1) polyimide precursor and the (a2) polyimide precursor may be imidized. The imidization ratio in this case is preferably 80% or less, more preferably 50% or less. The partial imidization is obtained by heating the polyimide precursor (a) to dehydrate and ring-close. The heating may be performed at a temperature of preferably 120 to 200 ℃, more preferably 150 to 180 ℃, for preferably 15 minutes to 20 hours, more preferably 30 minutes to 10 hours.

Further, by adding N, N-dimethylformamide dimethyl acetal or N, N-dimethylformamide diethyl acetal to the polyamic acid obtained by the above reaction, heating the mixture to esterify a part or all of the carboxylic acid, and then using the esterified product as the polyimide precursor (a) in the present embodiment, a resin composition having improved viscosity stability during storage at room temperature can also be obtained. Further, these ester-modified polyamic acids can also be obtained by the following method: the acid dianhydride component is reacted with 1 equivalent of monohydric alcohol and dehydration condensation agent such as thionyl chloride and dicyclohexylcarbodiimide in this order with respect to the acid anhydride group, and then condensed with the diamine component.

The proportion of the polyimide precursor (preferably polyamic acid) (a) in the resin composition of the present embodiment is preferably 3 to 50% by mass, more preferably 5 to 40% by mass, and particularly preferably 10 to 30% by mass, from the viewpoint of film formability.

< resin composition >

Another embodiment of the present invention provides a resin composition containing the polyimide precursor (a) and an organic solvent (b). The resin composition is typically a varnish.

[ (b) organic solvent ]

The organic solvent (b) in the present embodiment is not particularly limited as long as it can dissolve the polyimide precursor (a) and other components optionally used. As such (b) organic solvent, those which have been described above as solvents usable in the synthesis of the polyimide precursor (a) can be used. The preferred organic solvent is the same as described above. The organic solvent (b) in the resin composition of the present embodiment may be the same as or different from the solvent used for synthesizing the polyimide precursor (a).

(b) The organic solvent is preferably used in an amount such that the solid content concentration of the resin composition is 3 to 50 mass%. It is preferable to add the organic solvent (b) after adjusting the composition and amount of the organic solvent so that the viscosity (25 ℃) of the resin composition becomes 500 to 100000 mPas.

[ other ingredients ]

The resin composition of the present embodiment may further contain (c) a surfactant, (d) an alkoxysilane compound, and the like in addition to the components (a) and (b).

The resin composition of the present embodiment includes (a) a polyimide precursor, (b) an organic solvent, and at least 1 selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.

The skeleton of the polyimide precursor is not limited to the skeletons described above in the first and second embodiments. That is, the skeleton of the polyimide precursor is not particularly limited as long as it is a skeleton represented by the following general formula (1).

((c) surfactant)

By adding a surfactant to the resin composition of the present embodiment, the coatability of the resin composition can be improved. Specifically, the occurrence of streaks in the coating film can be prevented.

Examples of such surfactants include silicone surfactants, fluorine surfactants, and nonionic surfactants other than these surfactants. As an example of which the position of the first and second electrodes, respectively,

examples of the SILICONE surfactant include organosiloxane polymers KF-640, 642, 643, KP341, X-70-092, X-70-093, (trade name, manufactured by shin-Etsu chemical Co., Ltd.), SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (trade name, manufactured by DOW CORNING TORAY SILICONE CO., LTD., manufactured), SILWET L-77, L-7001, FZ-2105, FZ-2120, FZ-2154, FZ-2164, FZ-2166, L-7604 (trade name, manufactured by Nippon Unicar Co., Ltd.), DBE-814, DBE-224, DBE-621, CMS-626, CMS-222, KF-352A, KF-355A, 354L, KF-89355A, KF-355A, and KF-352-354-355A, KF-6020, DBE-821, DBE-712(Gelest), BYK-307, BYK-310, BYK-378, BYK-333 (trade name, BYK Japan KK.), Glanol (trade name, Kyoho chemical Co., Ltd.), etc.;

examples of the fluorine-containing surfactant include MEGAFAC F171, F173, R-08 (trade name, manufactured by DIC corporation), Fluorad FC4430, FC4432 (trade name, Sumitomo 3M Ltd.), and the like;

examples of the nonionic surfactant other than these include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene octylphenol ether.

Among these surfactants, from the viewpoint of coatability (stripe suppression) of the resin composition, a silicone surfactant and a fluorine surfactant are preferable, and from the viewpoint of the influence of the oxygen concentration in the curing step on the YI value and the total light transmittance, a silicone surfactant is preferable.

When the surfactant (c) is used, the amount thereof is preferably 0.001 to 5 parts by mass, and more preferably 0.01 to 3 parts by mass, based on 100 parts by mass of the polyimide precursor (a) in the resin composition.

(d) Alkoxysilane compound

In order to provide a resin film obtained from the resin composition of the present embodiment with sufficient adhesion to a support in a process for producing a flexible device or the like, the resin composition may contain 0.01 to 20 mass% of an alkoxysilane compound relative to 100 mass% of the polyimide precursor (a). By setting the content of the alkoxysilane compound to 0.01% by mass or more based on 100% by mass of the polyimide precursor, good adhesion to the support can be obtained. In addition, the content of the alkoxysilane compound of 20% by mass or less is preferable from the viewpoint of storage stability of the resin composition. The content of the alkoxysilane compound is more preferably 0.02 to 15% by mass, still more preferably 0.05 to 10% by mass, and particularly preferably 0.1 to 8% by mass, based on 100 parts by mass of the polyimide precursor.

By using an alkoxysilane compound as an additive for the resin composition of the present embodiment, in addition to the improvement of the adhesion described above, the coatability of the resin composition can be improved (stripe unevenness can be suppressed), and the oxygen concentration dependency of the YI value of the obtained cured film at the time of curing can be reduced.

Examples of the alkoxysilane compound include 3-ureidopropyltriethoxysilane, bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, γ -aminopropyltrimethoxysilane, γ -aminopropyltripropoxysilane, γ -aminopropyltributoxysilane, γ -aminoethyl triethoxysilane, γ -aminoethyl tripropoxysilane, γ -aminoethyl tributoxysilane, γ -aminoethyltributoxysilane, γ -aminobutyltriethoxysilane, γ -aminobutyltrimethoxysilane, γ -aminobutyltripropoxysilane, γ -aminobutyltributoxysilane, phenylsilanetriol, trimethoxyphenylsilane, trimethoxy (p-tolyl) silane, tri (n-tolyl) alkoxysilane, di (n-tolyl) triethoxysilane, tri (n-tolyl) alkoxysilane, di (n-amino-propyltriethoxysilane, tri (n-amino-propyltriethoxysilane, gamma-aminopropyl-tributoxysilane, gamma-aminoethyl tripropoxysilane, Diphenylsilanediol, dimethoxydiphenylsilane, diethoxydiphenylsilane, dimethoxydi-p-tolylsilane, triphenylsilanol, and alkoxysilane compounds represented by the following structures, and preferably 1 or more selected from them.

The method for producing the resin composition in the present embodiment is not particularly limited. For example, the following method may be followed.

When the solvent used for synthesizing the polyimide precursor (a) is the same as the organic solvent (b), the synthesized polyimide precursor solution can be used as it is as a resin composition. Further, the polyimide precursor may be used as a resin composition by adding 1 or more of (b) the organic solvent and other components to the polyimide precursor at a temperature ranging from room temperature (25 ℃) to 80 ℃ as required and stirring and mixing the mixture. The stirring and mixing can be carried out by using a suitable apparatus such as a Three-One Motor (manufactured by Xindong chemical Co., Ltd.) having a stirring blade, a rotary and revolutionary stirrer, or the like. In addition, heat of 40 to 100 ℃ may be applied as necessary.

On the other hand, when the solvent used in the synthesis of the polyimide precursor (a) is different from the organic solvent (b), the polyimide precursor (a) can be separated by removing the solvent from the synthesized polyimide precursor solution by an appropriate method such as reprecipitation or solvent distillation, and the organic solvent (b) and other components as required can be added at a temperature ranging from room temperature to 80 ℃ and mixed with stirring to prepare a resin composition.

After the resin composition is prepared as described above, the composition solution may be heated at 130 to 200 ℃ for, for example, 5 minutes to 2 hours, for example, to thereby dehydrate and imidize a part of the polyimide precursor to such an extent that the polymer is not precipitated. Here, the imidization ratio can be controlled by controlling the heating temperature and the heating time. By partially imidizing the polyimide precursor, the viscosity stability of the resin composition during storage at room temperature can be improved. The imidization ratio is preferably in the range of 5% to 70% from the viewpoint of obtaining a balance between the solubility of the polyimide precursor in the resin composition solution and the storage stability of the solution.

The resin composition of the present embodiment preferably has a water content of 3000 ppm by mass or less.

The water content of the resin composition is more preferably 1000 mass ppm or less, and still more preferably 500 mass ppm or less, from the viewpoint of viscosity stability when the resin composition is stored.

The resin composition of the present embodiment has a solution viscosity of preferably 500 to 200000 mPas, more preferably 2000 to 100000 mPas, and particularly preferably 3000 to 30000 mPas at 25 ℃. The solution viscosity can be measured using an E-type viscometer (VISCONICEHD, manufactured by eastern mechanical co., ltd.). When the solution viscosity is less than 300 mPas, the coating at the time of film formation is difficult, and when it is more than 200000 mPas, there is a problem that stirring at the time of synthesis is difficult.

When the polyimide precursor (a) is synthesized, even if the solution has a high viscosity, a resin composition having a viscosity that is good in handling properties can be obtained by adding a solvent and stirring after the reaction is completed.

In a preferred embodiment, the resin composition of the present embodiment has the following characteristics.

A resin film having a yellowness index YI of 30 or less at a film thickness of 10 μm is obtained by applying a resin composition to the surface of a support to form a coating film, and then heating the coating film at 300 to 550 ℃ in a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2000ppm or less) to imidize a polyimide precursor contained in the coating film.

After a resin composition is applied to the surface of a support to form a coating film, the coating film is heated at 300 to 550 ℃ in a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2000ppm or less) to imidize a polyimide precursor contained in the coating film, whereby the residual stress of the resulting resin film is 25MPa or less.

The resin composition of the present embodiment can be suitably used for forming a transparent substrate of a display device such as a liquid crystal display, an organic electroluminescence display, a field emission display, and electronic paper. Specifically, the method can be used for a substrate for forming a Thin Film Transistor (TFT), a substrate for a color filter, a substrate for a transparent conductive film (ITO, indium tin oxide), or the like.

The resin precursor of the present embodiment can form a polyimide film having a residual stress of 25MPa or less, and therefore can be easily applied to a display manufacturing process including a TFT element device on a colorless transparent polyimide substrate.

< resin film >

Another embodiment of the present invention provides a resin film formed from the resin precursor.

In another aspect, the present invention provides a method for producing a resin film from the resin composition.

The resin film according to the present embodiment is characterized by including the steps of:

a step (coating step) of forming a coating film by coating the resin composition on the surface of a support;

a step (heating step) of heating the support and the coating film to imidize a polyimide precursor contained in the coating film to form a polyimide resin film; and

and a step (peeling step) of peeling the polyimide resin film from the support.

Here, the support is not particularly limited as long as it has heat resistance at a heating temperature in the subsequent step and has good releasability. For example, a glass (e.g., alkali-free glass) substrate may be used;

a silicon wafer;

resin substrates such as PET (polyethylene terephthalate), OPP (oriented polypropylene), polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyamideimide, polyetherimide, polyetheretherketone, polyethersulfone, polyphenylsulfone, and polyphenylene sulfide;

and metal substrates such as stainless steel, aluminum, copper, and nickel.

For example, a glass substrate, a silicon wafer, or the like is preferable when forming a film-like polyimide molded body, and a support made of PET (polyethylene terephthalate), OPP (oriented polypropylene), or the like is preferable when forming a film-like or sheet-like polyimide molded body.

As the coating method, for example, a coating method such as a doctor blade coater (doctor blade coater), an air knife coater, a roll coater, a spin coater, a flow coater, a die coater, a bar coater, or the like, a coating method such as spin coating, spray coating, dip coating, or the like; printing techniques typified by screen printing, gravure printing, and the like.

The coating thickness is suitably adjusted depending on the desired thickness of the resin film and the content of the polyimide precursor in the resin composition, and is preferably about 1 to 1000 μm. The coating step is performed at room temperature, but may be performed by heating the resin composition at 40 to 80 ℃ for the purpose of reducing the viscosity and improving the workability.

After the coating step, a drying step may be performed, or the drying step may be omitted and the subsequent heating step may be performed as it is. This drying step is performed to remove the organic solvent. When the drying step is performed, a suitable apparatus such as a hot plate, a box dryer, or a conveyor dryer can be used. The drying step is preferably carried out at 80 to 200 ℃, more preferably at 100 to 150 ℃. The drying step is preferably performed for 1 minute to 10 hours, more preferably for 3 minutes to 1 hour.

In the above-described operation, a coating film containing a polyimide precursor is formed on a support.

Subsequently, a heating step is performed. The heating step is a step of removing the organic solvent remaining in the coating film in the drying step and performing an imidization reaction of the polyimide precursor in the coating film to obtain a film made of polyimide.

The heating step can be performed using an apparatus such as an inert gas oven, a hot plate, a box dryer, or a conveyor dryer. This step may be performed simultaneously with the drying step, or may be performed in two steps in sequence.

The heating step may be performed in an air atmosphere, and is preferably performed in an inert gas atmosphere from the viewpoint of safety, and transparency and YI value of the obtained polyimide film. Examples of the inert gas include nitrogen gas and argon gas.

The heating temperature may be appropriately set according to the type of the organic solvent (b), and is preferably 250 to 550 ℃, and more preferably 300 to 450 ℃. If the temperature is 250 ℃ or higher, imidization is sufficient, and if the temperature is 550 ℃ or lower, there is no problem such as deterioration in transparency and heat resistance of the obtained polyimide film. The heating time is preferably about 0.5 to 3 hours.

In the present embodiment, the oxygen concentration of the ambient atmosphere in the heating step is preferably 2000 mass ppm or less, more preferably 100 mass ppm or less, and still more preferably 10 mass ppm or less, from the viewpoint of the transparency and YI value of the polyimide film to be obtained. The YI value of the polyimide film obtained can be controlled to 30 or less by heating in an atmosphere having an oxygen concentration of 2000 mass ppm or less.

Depending on the use and purpose of the polyimide resin film, a peeling step of peeling the resin film from the support is required after the heating step. The peeling step is preferably performed after cooling the resin film on the support to about room temperature to 50 ℃.

Examples of the peeling step include the following (1) to (4).

(1) A method in which a structure comprising a polyimide resin film/support is produced by the above method, and then the polyimide resin is peeled off by irradiating the structure with laser light from the support side to ablate the interface between the support and the polyimide resin film. Examples of the laser include a solid-state (YAG) laser and a gas (UV excimer) laser. It is preferable to use a spectrum having a wavelength of 308nm or the like (see Japanese Kohyo publication No. 2007 and 512568, Japanese Kohyo publication No. 2012 and 511173, and the like).

(2) A method of forming a release layer on a support before coating the resin composition on the support, and then obtaining a structure comprising a polyimide resin film/release layer/support, and releasing the polyimide resin film. Examples of the method include a method using Parylene (registered trademark, manufactured by Parylene contract, japan) and tungsten oxide as a release layer; and a method using a release agent such as a vegetable oil-based, silicone-based, fluorine-based or alkyd-based release agent. (see Japanese patent application laid-open No. 2010-67957, Japanese patent application laid-open No. 2013-179306, etc.).

The laser irradiation of the method (2) and the aforementioned method (1) may be used in combination.

(3) A method in which an etchable metal substrate is used as a support to obtain a structure comprising a polyimide resin film/support, and then the metal is etched with an etchant to obtain a polyimide resin film. Examples of the metal include copper (specifically, electrolytic copper foil "DFF" manufactured by mitsui metal mining corporation) and aluminum. As the etchant, for copper, ferric chloride or the like can be used, and for aluminum, dilute hydrochloric acid or the like can be used.

(4) In the method described above, after the structure including the polyimide resin film/the support is obtained, the adhesive film is attached to the surface of the polyimide resin film, the adhesive film/the polyimide resin film is separated from the support, and then the polyimide resin film is separated from the adhesive film.

Among these peeling methods, the method (1) or (2) is suitable from the viewpoint of the difference in refractive index between the front surface and the back surface of the obtained polyimide resin film, the YI value, and the elongation, and the method (1) is more suitable from the viewpoint of the difference in refractive index between the front surface and the back surface of the obtained polyimide resin film.

In the case of using copper as the support in the method (3), the YI value of the obtained polyimide resin film tends to be large and the elongation tends to be small. This is considered to be the effect of copper ions.

The thickness of the resin film obtained by the above method is not particularly limited, but is preferably in the range of 1 to 200 μm, and more preferably 5 to 100 μm.

The yellow index YI of the resin thin film of the present embodiment may be 30 or less at a film thickness of 10 μm. The residual stress may be 25MPa or less. Particularly, the yellowness index YI at a film thickness of 10 μm is 30 or less and the residual stress is 25MPa or less. Such characteristics are favorably realized, for example, by imidizing the resin precursor of the present disclosure in a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2000ppm or less) at preferably 300 to 550 ℃, more preferably 350 to 450 ℃.

Further, the tensile elongation of the resin film of the present embodiment may be 15% or more. The tensile elongation of the resin film may be further 20% or more, and particularly may be 30% or more. The tensile elongation can be measured using a commercially available tensile tester using a resin film having a thickness of 10 μm as a sample.

The resin film of the present embodiment is a film made of a polyimide obtained by thermal imidization of the polyimide precursor (a1) contained in the resin composition. Therefore, the compound has a structural unit represented by the following general formula (11).

{ in formula (II), X₁、X₂Represents a tetravalent group having 4 to 32 carbon atoms. R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. Y is at least 1 selected from the group consisting of the aforementioned general formulae (3), (4) and (5). l and m independently represent an integer of 1 or more, and satisfy 0.01. ltoreq. l/(l + m). ltoreq.0.99. }

The lower limit of l/(l + m) may be 0.05, may be 0.10, may be 0.20, may be 0.30, may be 0.40.

The upper limit of l/(l + m) may be 0.95, may be 0.90, may be 0.80, may be 0.70, may be 0.60.

As described above, it is preferable that the residual stress is 25MPa or less, the YI is 30 or less, the glass transition temperature is 400 ℃ or more, the elongation is 15% or more, and the breaking strength is 250MPa or more.

In addition, a second embodiment is a film made of a polyimide obtained by thermal imidization of the polyimide precursor (a2) contained in the resin composition. Therefore, in the case of a resin film having a structural unit represented by the following general formula (12) and an elongation of 15% or more, it is preferable that the residual stress is 25MPa or less, the YI is 30 or less, the glass transition temperature is 400 ℃ or more, and the breaking strength is 250MPa or more.

{ in formula (II), X₃Represents a tetravalent group derived from at least 1 selected from 4,4 '-Oxybisphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA), and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ). R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group. n represents 0 or 1. And a, b and c are integers of 0 to 4. }

< laminate >

Another aspect of the present invention provides a laminate comprising a support and a polyimide resin film formed from the resin composition on a surface of the support.

In another aspect of the present invention, there is provided a method for producing the laminate.

The laminate according to the present embodiment can be obtained by a method for producing a laminate including the steps of:

a step (coating step) of coating the resin composition on the surface of a support to form a coating film; and

and a step (heating step) of heating the support and the coating film to imidize the polyimide precursor contained in the coating film to form a polyimide resin film.

The method for producing the laminate may be carried out in the same manner as the method for producing the resin film, except that, for example, the peeling step is not carried out.

The laminate can be suitably used, for example, in the manufacture of flexible devices.

The more detailed description is as follows.

In forming a flexible display, a glass substrate is used as a support, a flexible substrate is formed thereon, and further, formation of TFTs and the like is performed thereon. The step of forming a TFT or the like on a flexible substrate is typically performed at a wide temperature range of 150 to 650 ℃. However, in order to realize the actual desired performance, it is necessary to form a TFT-IGZO (InGaZnO) oxide semiconductor or a TFT (a-Si-TFT, poly-Si-TFT) using an inorganic material at a high temperature in the vicinity of 250 ℃ to 450 ℃.

On the other hand, the polyimide film tends to have a reduced physical property (particularly, yellowness index and elongation) due to the thermal history, and particularly, the yellowness index and elongation tend to be reduced when the temperature exceeds 400 ℃. However, the polyimide film obtained from the polyimide precursor of the present invention has only a small decrease in the yellowness index and elongation in a high temperature region of 400 ℃ or higher, and can be used favorably in this field.

Further, in the present embodiment, there can be provided a laminate comprising: a polyimide film layer containing a polyimide represented by the following general formula (13), and an LTPS (low temperature polysilicon TFT) layer.

The method for producing the laminate can be a method for producing a laminate comprising the support and a polyimide resin film formed from the resin composition on the surface of the support, then forming an amorphous Si layer, performing dehydrogenation annealing at 400 to 450 ℃ for about 0.5 to 3 hours, and then crystallizing the amorphous Si layer with an excimer laser or the like to form an LTPS layer. Then, the glass and the polyimide film are peeled off by laser peeling or the like, whereby the laminate can be obtained.

Peeling and swelling after a thermal cycle test of a laminate having a polyimide thin film layer containing a polyimide of the general formula (13) and an LTPS (low temperature polysilicon TFT) layer are small, and warpage of a substrate is small.

Further, as the residual stress generated between the flexible substrate and the polyimide resin film increases, the laminate formed by both expands in the TFT process at high temperature and then contracts when cooled at room temperature, which may cause problems such as warpage and breakage of the glass substrate and peeling of the flexible substrate from the glass substrate. In general, the glass substrate has a smaller thermal expansion coefficient than resin, and thus residual stress is generated between the glass substrate and the flexible substrate. As described above, the resin film of the present embodiment can reduce the residual stress generated between the resin film and the glass substrate to 25MPa or less, and thus can be suitably used for forming a flexible display.

Further, the yellow index YI at a film thickness of 10 μm of the polyimide film of the present embodiment may be 30 or less, and the tensile elongation may be 15% or more. As a result, the resin film of the present embodiment has excellent breaking strength when handling a flexible substrate, and therefore can improve the yield in manufacturing a flexible display.

In another embodiment, a polyimide film having a yellow index of 20 or less when the film is 10 μm thick and an absorbance of 0.6 to 2.0 at 308nm when the film is 0.1 μm thick after heating at 400 ℃ or higher and having an elongation of 15% or more can be provided.

By setting YI to 20 or less, a flexible substrate can be manufactured without degrading image quality when the display is manufactured.

More preferably 18 or less, and particularly preferably 16 or less.

When the absorbance at 308nm is 0.6 or more and 2.0 or less at a film thickness of 0.1 μm and the elongation is 15% or more, the polyimide film can be easily peeled from the glass substrate by laser, for example. From the viewpoint of suppressing the ash after laser lift-off, it is preferably 0.6 or more and 1.5 or less and the elongation is 20% or more, and from the viewpoint of not decreasing the performance of the organic EL element, for example, it is particularly preferably 0.6 or more and 1.0 or less and the elongation is 20% or more.

The upper limit of the elongation is not limited, and may be 80% or less, 70% or less, 60% or less, 50% or less, or 40% or less.

In the laser lift-off, the polyimide film may be burned by the laser beam, and the combustion residue may be ash.

Therefore, another embodiment of the present invention provides a display substrate.

In addition, another embodiment of the present invention provides a method for manufacturing the display substrate.

The method for manufacturing a display substrate according to the present embodiment includes:

a step (coating step) of coating the resin composition on the surface of a support to form a coating film;

a step (heating step) of heating the support and the coating film to imidize a polyimide precursor contained in the coating film to form a polyimide resin film;

a step of forming an element or a circuit on the polyimide resin film (element/circuit forming step); and

and a step (peeling step) of peeling the polyimide resin film on which the element or the circuit is formed from the support.

In the above method, the coating step, the heating step, and the peeling step may be performed in the same manner as in the above method for producing a resin film.

The element/circuit forming process may be performed by a method known to those skilled in the art.

The resin film of the present embodiment satisfying the above physical properties is suitable for applications in which the use of the conventional polyimide film is limited due to its yellow color, particularly for applications such as a colorless transparent substrate for a flexible display and a protective film for a color filter. Furthermore, the film can be used in fields where colorless transparency and low birefringence are required, such as protective films, diffusion sheets and coating films in TFT-LCDs, etc. (for example, interlayers of TFT-LCDs, gate insulating films, liquid crystal alignment films, etc.), ITO substrates for touch panels, cover glass for smartphones, and the like, instead of resin substrates. When the polyimide of the present embodiment is applied as a liquid crystal alignment film, a TFT-LCD having a high aperture ratio and a high contrast ratio can be manufactured.

The polyimide precursor and the resin film and the laminate produced using the resin precursor of the present embodiment can be suitably used as, for example, a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, or the like, and can be particularly suitably used as a substrate in the production of a flexible device. Here, examples of the flexible device to which the resin film and the laminate of the present embodiment can be applied include a flexible display, a flexible solar cell, a flexible touch panel electrode substrate, a flexible lighting, a flexible battery, and the like.

Examples

The present invention will be described in more detail below with reference to examples, which are described for illustrative purposes, and the scope of the present invention is not limited to the following examples.

Various evaluations in examples and comparative examples were performed as follows.

< determination of weight average molecular weight >

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by Gel Permeation Chromatography (GPC) under the following conditions.

As the solvent, N-dimethylformamide (manufactured by Wako pure chemical industries, Ltd., for high performance liquid chromatography, and obtained by adding and dissolving 24.8mmol/L of lithium bromide monohydrate (manufactured by Wako pure chemical industries, Ltd., purity 99.5%) and 63.2mmol/L of phosphoric acid (manufactured by Wako pure chemical industries, Ltd., for high performance liquid chromatography) immediately before the measurement) was used. A calibration curve for calculating the weight average molecular weight was prepared using standard polystyrene (manufactured by Tosoh Corporation).

Column: shodex KD-806M (made by Showa Denko K.K.)

Flow rate: 1.0 mL/min

Column temperature: 40 deg.C

A pump: PU-2080Plus (JASCO products.)

A detector: RI-2031Plus (RI: differential refractometer, manufactured by JASCO Co., Ltd.) and UV-2075Plus (UV-VIS: ultraviolet-visible absorptiometer, manufactured by JASCO Co., Ltd.)

< evaluation of content of molecule having molecular weight of less than 1000 (Low molecular weight Mass content) >

The content of molecules having a molecular weight of less than 1000 in the resin was calculated as the ratio (percentage) of the peak area occupied by the component having a molecular weight of less than 1000 to the peak area of the entire molecular weight distribution using the measurement result of GPC obtained as described above.

< evaluation of moisture content >

The amounts of water in the synthesis solvent and the resin composition (varnish) were measured using a Karl Fischer moisture measuring apparatus (trace moisture measuring apparatus AQ-300, manufactured by Hei Marsh industries, Ltd.).

< evaluation of viscosity stability of resin composition >

For the resin compositions prepared in each of the examples and comparative examples,

taking a sample which is prepared and then stands for 3 days at room temperature as a prepared sample, and carrying out viscosity measurement at 23 ℃;

the sample which was then allowed to stand at room temperature for 2 weeks was taken as a sample after 2 weeks, and the viscosity measurement at 23 ℃ was performed again. These viscosity measurements were performed using a viscometer with a temperature controller (TOKI sangyo.co., ltd. TV-22).

Using the measured values, the viscosity change rate at room temperature for 2 weeks was calculated by the following numerical expression.

Viscosity change rate (%) at room temperature for 2 weeks [ (viscosity of sample after 2 weeks) - (viscosity of sample after preparation) ]/(viscosity of sample after preparation) × 100

The viscosity change rate at 2 weeks at room temperature was evaluated according to the following criteria.

Very good: viscosity change rate of 5% or less (Excellent storage stability)

O: the viscosity change rate was more than 5% and 10% or less (storage stability "good")

X: the viscosity change rate was more than 10% (poor storage stability)

< evaluation of varnish coatability >

The resin compositions prepared in each of examples and comparative examples were coated on an alkali-free glass substrate (size 37X 47mm, thickness 0.7mm) using a bar coater so that the film thickness was 15 μm after curing, and then prebaked at 140 ℃ for 60 minutes.

The coatability of the varnish was evaluated by measuring the level difference of the surface of the coating film using a level difference meter (model name P-15, manufactured by Tencor).

Very good: the height difference of the surface was 0.1 μm or less (coating property was "excellent")

O: the height difference of the surface exceeded 0.1 μm and was 0.5 μm or less (coatability "good")

X: the difference in height of the surface was more than 0.5. mu.m (coatability "poor")

< evaluation of residual stress >

Each resin composition was applied to a 6-inch silicon wafer having a thickness of 625 μm. + -. 25 μm and a "warpage amount" measured in advance by a spin coater, and prebaked at 100 ℃ for 7 minutes. Then, a silicon wafer with a polyimide resin film having a thickness of 10 μm after curing was prepared by performing a heat curing treatment (curing treatment) at 430 ℃ for 1 hour so that the oxygen concentration in the chamber was adjusted to 10ppm by mass or less using a vertical curing furnace (model name VF-2000B manufactured by Toyoyo Lindberg Co., Ltd.).

The warpage amount of the wafer was measured by using a residual stress measuring apparatus (product of Tencor Corporation, model name FLX-2320), and the residual stress generated between the silicon wafer and the resin film was evaluated.

Very good: a residual stress of more than-5 MPa and 15MPa or less (evaluation of residual stress "Excellent")

O: a residual stress of more than 15MPa and not more than 25MPa (evaluation of residual stress "good")

X: residual stress exceeding 25MPa (evaluation of residual stress "poor")

< evaluation of warpage of inorganic film-formed polyimide resin film >

The resin compositions prepared in each of examples and comparative examples were spin-coated on a 6-inch silicon wafer substrate provided with an aluminum evaporated layer on the surface thereof so that the film thickness after curing was 10 μm, and prebaked at 100 ℃ for 7 minutes. Then, a wafer having a polyimide resin film formed thereon was prepared by performing a heat curing treatment at 430 ℃ for 1 hour, with the oxygen concentration in the chamber adjusted to 10 mass ppm or less, using a vertical curing furnace (model name VF-2000B, manufactured by Toyoyo Lindberg Co., Ltd.). Using this wafer, a silicon nitride (SiNx) film as an inorganic film was formed on a polyimide resin film by a CVD method at 350 ℃ and a thickness of 100nm, to obtain a laminate wafer on which the inorganic film/polyimide resin was formed.

The laminate wafer obtained above was immersed in a dilute hydrochloric acid aqueous solution, and the two layers of the inorganic film and the polyimide film were peeled off from the wafer as a single body, thereby obtaining a sample of a polyimide film having an inorganic film formed on the surface thereof. Using this sample, the warpage of the polyimide resin film was evaluated.

Very good: no warpage (warpage "Excellent")

O: almost no warpage (warpage "good")

X: curling of the film due to warping (warping "poor")

< evaluation of yellowness index (YI value) >

Wafers (wafers without an inorganic film) were produced in the same manner as in the above-described < evaluation of warpage of a polyimide resin film with an inorganic film formed >. The wafer was immersed in a dilute hydrochloric acid aqueous solution to peel off the polyimide resin film, thereby obtaining a resin film.

The YI value (in terms of a film thickness of 10 μm) of the obtained polyimide resin film was measured using a D65 light source, manufactured by Nippon Denshoku industries Co., Ltd. (Spectrophotometer: SE 600).

< evaluation of elongation and breaking Strength >

Wafers (wafers without an inorganic film) were produced in the same manner as in the above-described < evaluation of warpage of a polyimide resin film with an inorganic film formed >. After a 3mm wide crack was cut in the polyimide resin film of the wafer using a dicing saw (DAD 3350 manufactured by Disco Corporation), the wafer was immersed in a dilute hydrochloric acid aqueous solution overnight, and the resin film sheet was peeled off and dried. It was cut into a length of 50mm as a sample.

For the above samples, elongation and breaking strength were measured at a test speed of 40 mm/min and an initial load of 0.5fs using TENSILON (Orientec, manufactured by Inc.) for the above samples.

< measurement of Absorbance at 308nm of polyimide resin film >

The varnish was spin-coated on a quartz glass substrate, and the substrate was heated at 430 ℃ for 1 hour under a nitrogen atmosphere to obtain a polyimide resin film having a thickness of 0.1. mu.m. For these polyimide films, absorbance at 308nm was measured using UV-1600 (manufactured by Shimadzu Corporation).

[ example 1]

96g of N-methyl-2-pyrrolidone (NMP), 17.71g (77.6mmol) of 4-aminophenyl-4-aminobenzoate (APAB) and 4.82g (19.4mmol) of 4, 4' -diaminodiphenyl sulfone (DAS) were placed in a 500ml separable flask purged with nitrogen, and APAB and DAS were dissolved with stirring. Then, 29.42g (100mmol) of biphenyl-3, 3 ', 4, 4' -tetracarboxylic dianhydride (BPDA) was added thereto, and polymerization was carried out under a nitrogen flow at 80 ℃ for 3 hours with stirring. Then, the mixture was cooled to room temperature, and the solution viscosity was adjusted to 51000mPa · s by adding NMP to obtain an NMP solution (hereinafter, also referred to as varnish) P-1 of polyamic acid. The weight average molecular weight (Mw) of the obtained polyamic acid was 65000.

Examples 2 to 21 and comparative examples 1 to 5

Varnishes P-2 to P-26 were obtained in the same manner as in example 1, except that the amounts (molar ratios) of the raw materials charged, the kinds of the solvents used, the polymerization temperatures, and the polymerization times in example 1 were changed as shown in table 1.

Table 1 also shows the weight average molecular weight (Mw) of the polyamic acid contained in each varnish.

[ Table 1]

The abbreviations for the respective components in table 1 have the following meanings.

BPDA: 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride

And (3) PMDA: pyromellitic dianhydride

TAHQ: p-phenylene bis (trimellitic acid monoester anhydride)

APAB: 4-aminophenyl-4-aminobenzoic acid ester

ATAB: 2-methyl-4-aminophenyl-4-aminobenzoic acid ester

BABB: [4- (4-aminobenzoyl) oxyphenyl ] 4-aminobenzoate

BAFL: 9, 9-bis (aminophenyl) fluorenes

BFAF: 9, 9-bis (4-amino-3-fluorophenyl) fluorene

TFMB: 2. 2' -bis (trifluoromethyl) benzidine

DAS: 4, 4' -diaminodiphenyl sulfone

NMP: n-methyl-2-pyrrolidone

DMF: n, N-dimethylformamide

DMAc: n, N-dimethyl acetamide

Varnishes P-1 to P-26 obtained in the above examples and comparative examples were used as resin compositions as they were, and evaluated according to the methods described above. The evaluation results are shown in Table 2.

[ Table 2]

Indicates that the film is brittle and cannot be measured

Whitening of the film and thus no measurement was made

As is apparent from tables 1 and 2, the polyimide films obtained in comparative examples 1 and 2, which contain only the structural unit represented by the general formula (1), were brittle and could not be evaluated for physical properties such as elongation. In addition, the residual stress is also high. The polyimide film obtained in comparative example 3, which contained only the structural unit represented by the general formula (2), had a high residual stress, and was warped after the formation of the inorganic film, and had a low elongation.

On the other hand, the polyimide films obtained in examples 1 to 21, which contained the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) in the molar ratio of 99/1 to 1/99, had the results that the yellowness index was as low as 20 or less, the residual stress was 25MPa or less, and the elongation was as high as 20% or more. Further, no or very little warpage occurred after the formation of the inorganic film.

From the results shown in table 2, it was confirmed that the polyimide resin film obtained from the resin composition of the present invention was a resin film having a small yellow index, a low residual stress and excellent mechanical properties.

Specifically, in the present invention, a resin film having a residual stress of 25MPa or less, a yellow index YI of 30 or less, and an elongation of 15% or more is obtained.

[ example 22]

N-methyl-2-pyrrolidone (NMP) (water content 250 mass ppm) in an amount corresponding to 17 wt% of the solid content immediately after the 18L jar was opened was placed in a 500ml separable flask purged with nitrogen, 5.71g (25.0mmol) of 4-aminophenyl-4-aminobenzoate (APAB, purity 99.5%, manufactured by Nippon Kagaku K.K.) was placed therein, and the APAB was dissolved by stirring. Then, 7.36g (25.0mmol) of biphenyl-3, 3 ', 4, 4' -tetracarboxylic dianhydride (BPDA, purity 99.5%, manufactured by MANAC Inc.) was added thereto, and polymerization was carried out under a nitrogen flow at 80 ℃ for 3 hours with stirring. Then, the mixture was cooled to room temperature, and the solution viscosity was adjusted to 51000mPa · s by adding NMP to obtain an NMP solution (hereinafter, also referred to as varnish) P-27 of polyamic acid. The weight average molecular weight (Mw) of the obtained polyamic acid was 128000, and the content of molecules having a molecular weight of less than 1000 was 0.01 mass%.

Examples 23 to 33 and comparative examples 6 to 11

Varnishes P-28 to P-44 were obtained in the same manner as in Synthesis example 1, except that the types of raw materials, the amounts of raw materials charged, the types of solvents used, the polymerization temperatures and the polymerization times in example 22 were changed to those shown in Table 3.

Table 3 also shows the weight average molecular weight (Mw) of the polyamic acid contained in each varnish.

[ Table 3]

The abbreviations for the respective components in table 3 have the following meanings.

BPDA: biphenyl tetracarboxylic dianhydride, purity 99.5%, manufactured by Mitsubishi chemical corporation

TAHQ: p-phenylene bis (trimellitic acid monoester anhydride) purity 99.5%, manufactured by MANAC Inc

And (3) PMDA: pyromellitic dianhydride

APAB: 4-aminophenyl-4-aminobenzoate with a purity of 99.5%

4, 3-APAB: 4-aminophenyl-3-aminobenzoate with purity of 99.5%

ATAB: 2-methyl-4-aminophenyl-4-aminobenzoic acid ester

BABB: [4- (4-aminobenzoyl) oxyphenyl ] 4-aminobenzoate

NMP 1: moisture content of 250ppm immediately after opening and sealing of 18L can

NMP 2: opening the bottle with 500ml, standing for one month, and keeping the water content at 3070ppm

DMF: after the bottle of 500ml is opened, the water content is 3510ppm

DMAc: after the bottle of 500ml is opened and sealed, the water content is 3430ppm

Examples 22 to 33 and comparative examples 6 to 11

Varnishes P-27 to P-44 obtained in the above examples and comparative examples were directly used as resin compositions and evaluated by the above-described methods. The evaluation results are shown in Table 4.

[ Table 4]

As is apparent from tables 3 and 4, the polyimide precursor (varnish) had a weight average molecular weight of 30000 or less in comparative example 6(P-39), comparative example 7(P-40), comparative example 8(P-41), comparative example 10(P-43) and comparative example 11(P-44), which exhibited a large residual stress and a large warpage. In addition, the yellowness index is large, and the elongation and breaking strength are also small. In particular, in comparative examples 10 and 11, in which the water content was large, the film was very brittle.

On the other hand, in comparative example 9(P-42) in which the weight average molecular weight of the polyimide precursor was 300000 or more, the residual stress and warpage were small, the yellow index was also low, and the elongation and the breaking strength were also large, but the coatability was deteriorated.

On the other hand, in examples 22 to 33 using polyimide precursors P-27 to P-38 having a weight average molecular weight of 30000 or more and 300000 or less, the residual stress was low, the warpage was small, the yellow index was low, the elongation and the breaking strength were large, and the results were excellent in each property.

From the results shown in table 4, it was confirmed that the polyimide resin film obtained from the resin composition of the present invention was a resin film having a small yellow index, a low residual stress and excellent mechanical properties.

Specifically, in the present invention, a resin film having a residual stress of 25MPa or less, a yellow index YI of 20 or less, a glass transition temperature of 400 ℃ or more, an elongation of 15% or more, and a breaking strength of 250MPa or more can be obtained.

In examples 34 to 45 shown below, experiments were conducted on the effects in the case where at least one selected from the group consisting of a surfactant and an alkoxysilane compound was added to the resin composition.

[ example 34]

First, the varnish P-27 obtained in the above example 22 was used as it is as a resin composition, and the evaluation of the coating stripes was performed by the following procedure.

< evaluation of coating Strand (coatability) >)

The resin composition was coated on an alkali-free glass substrate (37X 47mm in size and 0.7mm in thickness) using a bar coater so that the film thickness after curing was 15 μm. After the coating, the coating film was left at room temperature for 10 minutes, and then whether or not coating streaks were generated on the obtained coating film was visually confirmed. The same resin composition was used for coating 3 times, the number of coating stripes was examined for each coating film, and the average value was evaluated according to the following criteria.

Very good: the number of continuous coating stripes having a width of 1mm or more and a length of 1mm or more was 0 (evaluation of coating stripes "excellent")

O: the above coating stripes were 1 or 2 (evaluation of coating stripes "good")

And (delta): the coating stripes were 3 to 5 (evaluation of coating stripes "ca")

The evaluation results are shown in Table 5.

[ examples 35 to 45]

To the varnish P-27 obtained in the above example 22, as additional additives, surfactants or alkoxysilane compounds of the kinds and amounts shown in table 5 were added, respectively, and then filtered with a 0.1 μm filter to prepare a resin composition.

Using the resin composition, coating stripes were evaluated in the same manner as in example 34. The results are shown in Table 5.

[ Table 5]

TABLE 5 evaluation results of the resin compositions (2)

The abbreviations for the respective components in table 5 have the following meanings. The amounts of these components used in table 5 are the amounts (amounts) of compounding per 100 parts by mass of the polyimide precursor contained in the varnish. In examples 39 and 45, surfactant 1 and alkoxysilane compound 1 were used in combination.

Surfactant 1: DBE-821, product name, silicone surfactant, and Gelest

Surfactant 2: MEGAFAC F171, PRODUCT NAME, FLUORO-BASED SURFACTANT, DIC PRODUCT

Alkoxysilane compound 1: a compound represented by the following general formula (AS-1)

Alkoxysilane compound 2: a compound represented by the following general formula (AS-2)

As is apparent from table 5, in examples 35 to 39 and examples 41 to 45 containing a surfactant or an alkoxysilane compound, the occurrence of coating streaks was suppressed and polyimide resin films having excellent surface smoothness were obtained as compared with examples 34 and 40 not containing both.

[ example 46]

Using a bar coater, the varnish P-27 was coated on an alkali-free glass substrate (size 37X 47mm, thickness 0.7mm) so that the film thickness after curing was 10 μm, and then prebaked at 140 ℃ for 60 minutes. Subsequently, a vertical curing furnace (model name VF-2000B, manufactured by Toyobo Lindberg Co., Ltd.) was used to adjust the oxygen concentration in the chamber to 10ppm by mass or less, and heat curing treatment was performed at 430 ℃ for 1 hour to prepare a glass substrate on which a polyimide resin film was formed. An amorphous silicon layer was formed on the polyimide film, and dehydrogenation annealing was performed at 430 ℃ for 1 hour, followed by irradiation of excimer laser, thereby forming an LTPS layer. The glass substrate was peeled off by an excimer laser (wavelength 308nm, repetition frequency 300Hz) to obtain a laminate comprising a polyimide film and an LTPS layer.

The laminate is free from warpage and has a yellowness index of 20 or less.

[ example 47]

A laminate was obtained in the same manner as in example 46, except that varnish P-1 was used. The laminate is free from warpage and has a yellowness index of 20 or less.

Comparative example 12

A laminate was obtained in the same manner as in example 46, except that varnish P-24 was used. The laminate had a large warpage, and cracks were generated in a part of the polyimide film.

[ Synthesis examples ]

In a separable flask equipped with a dean Stark apparatus and a reflux device, 2.24g (9.8mmol) of APAB, 16.14g of NMP and 50g of toluene were placed under a nitrogen atmosphere, and APAB was dissolved with stirring. 2.24g (10.0mmol) of H-PMDA was added thereto, and after refluxing at 180 ℃ for 2 hours, toluene as an azeotropic solvent was removed over 3 hours. The contents of the flask were cooled to 40 ℃ and 1650cm from the amide bond was confirmed by IR^-1The nearby absorption (C ═ O) disappears. Then, APAB 8.95g (39.2mmol), NMP 121.6g, PMDA 6.54g (30.0mmol) and 6FDA 4.44g (10.0mmol) were added thereto, and the mixture was stirred at 80 ℃ for 4 hours to obtain a varnish of a polyimide-polyamic acid polymer (P-45). The weight average molecular weight (Mw) of the obtained polyimide-polyamic acid polymer was 82000.

Examples 48 to 53 and comparative example 13

An organic EL substrate as shown in fig. 1 was produced.

Polyimide precursor varnishes (P-1, P-11, P-20, P-22, P-27, P-33, P-45) were coated on a mother glass substrate (thickness 0.7mm) using a bar coater so that the film thickness was 10 μm after curing, and then prebaked at 140 ℃ for 60 minutes. Subsequently, a vertical curing furnace (model name VF-2000B, manufactured by Toyobo Lindberg Co., Ltd.) was used to adjust the oxygen concentration in the chamber to 10ppm by mass or less, and heat curing treatment was performed at 430 ℃ for 1 hour to prepare a glass substrate on which a polyimide resin film was formed.

Next, a SiN layer was formed to a thickness of 100nm by a CVD (chemical vapor deposition) method.

Next, a film of titanium was formed by sputtering, and then, patterning was performed by photolithography to form scanning signal lines.

Next, a SiN layer was formed to a thickness of 100nm by a CVD method on the entire glass substrate on which the scanning signal lines were formed. (Up to this point, the lower substrate 2a is used)

Next, an amorphous silicon layer 256 was formed on the lower substrate 2a, and dehydrogenation annealing was performed at 430 ℃ for 1 hour, followed by irradiation of excimer laser, thereby forming an LTPS layer.

Then, a photosensitive acrylic resin was applied to the entire surface of the lower substrate 2a by a spin coating method, and exposed and developed by photolithography to form 258 having a plurality of contact holes 257. The contact hole 257 exposes a part of each LTPS 256.

Next, an ITO film is formed by sputtering on the entire surface of the lower substrate 2a on which the interlayer insulating film 258 is formed, and the lower electrode 259 is formed by exposure and development by photolithography, patterning by etching, and forming a pair with each LTPS.

In each contact hole 257, the lower electrode 252 penetrating the interlayer insulating film 258 is electrically connected to the LTPS 256.

Next, after the partition 251 is formed, the hole transport layer 253 and the light-emitting layer 254 are formed in each space defined by the partition 251. In addition, the upper electrode 255 is formed so as to cover the light-emitting layer 254 and the partition wall 251. The organic EL substrate 25 is produced through the above steps.

Next, an ultraviolet curable resin is applied around the sealing substrate 2b on which the glass substrate and the polyimide film and the SiN layer of the present embodiment are sequentially formed, and the sealing substrate 2b and the organic EL substrate are bonded in an argon atmosphere, thereby sealing the organic EL element. Thereby, the hollow portion 261 is formed before each organic EL element and the sealing substrate 2 b.

The laminate thus formed was irradiated with excimer laser light (wavelength 308nm, repetition frequency 300Hz) from the lower substrate 2a side and the sealing substrate 2b side, and peeled off with the minimum energy required for peeling off the entire surface.

For this laminate, warpage of the substrate after peeling, a lighting test, and an evaluation of white turbidity of the laminate were performed. In addition, a thermal cycle test was also performed. The results are shown in Table 6.

< warpage of substrate >

Very good: no warp

O: almost no warpage

And (delta): curling due to warping

< Lighting test >

O: light on

X: unlit

< evaluation of haze of laminate >

After the laminate was formed, the case where the entire device was transparent was marked as "o", the case where the device was slightly clouded was marked as "Δ", and the case where clouding occurred was marked as "x".

< Heat cycle test >

Using an ESPEC heating cycle tester, 1000 cycle tests were carried out at-5 ℃ and 60 ℃ for 30 minutes (1 minute moving time of the cell), respectively, and then appearance observation was carried out.

The case where no peeling or swelling was observed after the test was evaluated as "o", the case where peeling or swelling was observed in a small portion after the test was evaluated as "Δ", and the case where peeling or swelling was observed over the entire surface after the test was evaluated as "x".

[ Table 6]

Examples 54 to 58 and comparative example 14

The above test was carried out except that the laminate was produced using polyimide precursor varnishes (P-1, P-11, P-20, P-22, P-27, P-33 and P-45) and LTPS was IGZO. The results are shown in Table 7.

[ Table 7]

Examples 59 to 63 and comparative example 15

The minimum energy required for laser lift-off in the above laser lift-off and the sum of the minimum energy and 10mJ/cm²The obtained energy was evaluated for ash (ash content) when the polyimide precursor varnish (P-1, P-11, P-20, P-27, P-33, P-45) having YI of 20 or less, an absorbance at 308nm of 0.1 μm or more and 2.0 or less and an elongation of 15% or more was irradiated. The case where no ash was generated was rated as "O", the case where a little ash was observed at the edge was rated as "Delta", and the case where ash was observed over the entire surface was rated as "X". The results are shown in Table 8.

[ Table 8]

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

Industrial applicability

The resin film formed from the polyimide precursor of the present invention can be used, for example, as a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, or the like, and can be suitably used, in particular, as a substrate in the production of a flexible display, a substrate for an ITO electrode of a touch panel, or the like.

Claims

1. A (a1) polyimide precursor characterized by comprising a structural unit L represented by the following general formula (1) and a structural unit M represented by the following general formula (2) in a ratio of 1/99 or less (number of moles of the structural unit L/number of moles of the structural unit M) or less 99/1,

in the formula (1), X₁Represents a tetravalent group having 4 to 32 carbon atoms, R₁、R₂、R₃Each independently represents a C1-20 monovalent organic group, n represents 0 or 1, and a, b and c are integers of 0-4,

in the formula (2), X₂Represents a tetravalent group having 4 to 32 carbon atoms, Y represents at least 1 selected from the group consisting of the following general formulae (3), (4) and (5),

in the formulae (3), (4), (5), R₄～R₁₁Each independently represents a monovalent organic group having 1 to 20 carbon atoms, and d to k are integers of 0 to 4.

2. The polyimide precursor according to claim 1, wherein n in the general formula (1) is 0.

3. The polyimide precursor according to claim 1 or 2, wherein Y of the general formula (2) is a general formula (3).

4. The polyimide precursor according to claim 1 or 2, wherein Y of the general formula (2) is a general formula (4).

5. The polyimide precursor according to claim 1 or 2, wherein Y of the general formula (2) is a general formula (5).

6. A polyimide precursor (a2) characterized by having a structural unit represented by the following general formula (10) and having a weight-average molecular weight of 30000 or more and 300000 or less,

in the formula (10), X₃Represents a tetravalent group derived from at least 1 selected from the group consisting of 4,4 '-Oxydiphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA) and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ), R₁、R₂、R₃Each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4.

7. The polyimide precursor according to claim 6, wherein the content of molecules having a weight average molecular weight of less than 1000 in the (a2) polyimide precursor is less than 5% by mass.

8. The polyimide precursor according to claim 6 or 7, wherein n in the general formula (10) is 0.

9. The polyimide precursor according to any one of claims 1 to 5, wherein X is₁、X₂Is a tetravalent organic group derived from at least 1 selected from the group consisting of pyromellitic dianhydride (PMDA), 4 '-Oxydiphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA), and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ).

10. A resin composition comprising the polyimide precursor according to any one of claims 1 to 9 and (b) an organic solvent.

11. The resin composition according to claim 10, further comprising at least 1 selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.

12. A polyimide characterized by having a structural unit represented by the following general formula (11),

in formula (11), X₁、X₂Represents a tetravalent group having 4 to 32 carbon atoms, R₁、R₂、R₃Each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4, Y is at least 1 selected from the group consisting of the following general formulae (3), (4) and (5), l and m each independently represents an integer of 1 or more, 0.01. ltoreq. l/(l + m). ltoreq.0.99,

13. A polyimide which has a structural unit represented by the following general formula (12) and has an elongation of 15% or more,

in the formula (12), X₃Represents a tetravalent group derived from at least 1 selected from the group consisting of 4,4 '-Oxydiphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA) and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ), R₁、R₂、R₃Each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4.

14. A method for manufacturing a resin film, comprising the steps of:

a step of applying the resin composition according to claim 10 or 11 on the surface of a support to form a coating film;

and a step of peeling the polyimide resin film from the support.

15. The method of producing a resin film according to claim 14,

the step of irradiating the polyimide resin film with a laser beam from the support body side is performed before the step of peeling the polyimide resin film from the support body.

16. A method for manufacturing a laminate, comprising the steps of:

a step of applying the resin composition according to claim 10 or 11 on the surface of a support to form a coating film; and

17. A method for manufacturing a display substrate, comprising:

forming an element or a circuit on the polyimide resin film; and

18. A polyimide film for display, which comprises a polyimide represented by the following general formula (12),

in the formula (12), X₃Is at least 1 selected from the group consisting of 4,4 '-Oxydiphthalic Dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA) and 4, 4' -biphenylbis (trimellitic acid monoester anhydride) (TAHQ), R₁、R₂、R₃Each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4.

19. A laminate, comprising: a polyimide thin film layer comprising a polyimide represented by the following general formula (13) and a low-temperature polysilicon TFT layer,

in formula (13), X₁Represents a tetravalent group having 4 to 32 carbon atoms, R₁、R₂、R₃Each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4.

20. A polyimide film characterized by having a yellow index of 20 or less when the film is 10 μm thick, an absorbance at 308nm of 0.6 to 2.0 when the film is 0.1 μm thick, and an elongation of 15% or more after heating at 400 ℃ or more.

21. A resin composition, comprising:

(a) a polyimide precursor represented by the following general formula (1),

(b) An organic solvent, and

at least 1 selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound,

in the formula (1), X₁Represents a tetravalent group having 4 to 32 carbon atoms, R₁、R₂、R₃Each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4.