CN113549217A

CN113549217A - Polyimide precursor, resin composition containing same, polyimide resin film, and method for producing same

Info

Publication number: CN113549217A
Application number: CN202110441249.6A
Authority: CN
Inventors: 加藤聪; 佐藤雄太
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp
Priority date: 2020-04-24
Filing date: 2021-04-23
Publication date: 2021-10-26
Anticipated expiration: 2041-04-23
Also published as: CN113549217B

Abstract

A polyimide precursor and a resin composition containing the same, a polyimide resin film, a resin film and a method for producing the same. Provided are a polyimide resin film which has low residual stress, low warpage, low yellowness (YI value) at high temperatures (particularly 430 ℃ or higher), low Haze (Haze value), and excellent laser peelability from a substrate, and a method for producing the same. A polyimide precursor comprising (a1) a structural unit L represented by the general formula (1) and (a2) a structural unit M represented by the general formula (2), wherein the ratio of the amount of the structural unit M to the total amount of the structural unit L and the structural unit M is 0.005 to 0.5 mol%.

Description

Polyimide precursor, resin composition containing same, polyimide resin film, and method for producing same

Technical Field

The present invention relates to a polyimide precursor used in, for example, the production of a substrate for a flexible device, and a resin composition, a polyimide resin film, a resin film, and a method for producing the same.

Background

In general, in applications requiring high heat resistance, a film of a polyimide resin is used as a resin film. A general polyimide resin is a highly heat-resistant resin produced by producing a polyimide precursor by solution polymerization of an aromatic carboxylic dianhydride and an aromatic diamine, 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 materials, insulating films, semiconductors, and electrode protective films for thin film transistor liquid crystal displays (TFT-LCDs). Recently, instead of glass substrates which have been used in the field of display materials, their use as flexible substrates utilizing their lightweight and flexibility has been studied.

When a polyimide resin is used as a flexible substrate, the following steps are widely used: for example, a varnish containing a polyimide resin or a precursor thereof and other components is applied to an appropriate support such as a glass substrate, dried to form a thin film, and then an element, a circuit, or the like is formed on the thin film, and then the thin film is peeled off from the glass substrate. However, in the production of a laminate having a polyimide resin, a heat treatment at a high temperature of 250 ℃ or higher is performed for the purpose of drying and imidization of a polyimide precursor. The heat treatment causes a residual stress in the laminate, and serious problems such as warpage and peeling occur. This is because: the polyimide has a higher linear expansion coefficient than the material constituting the support.

In order to reduce the residual stress in the laminate, the use of a polyimide resin having a small thermal expansion coefficient comparable to that of glass has been studied, and a polyimide comprising 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA) and p-phenylenediamine is most well known as a polyimide material having a small thermal expansion coefficient. Although depending on the film thickness and the production conditions, it is reported that the polyimide exhibits a very low linear thermal expansion coefficient (non-patent document 1).

Further, it is reported that a polyimide having an ester structure in a molecular chain has a low linear expansion coefficient because of appropriate linearity and rigidity (patent document 1).

However, general polyimide resins, including the polyimides described in the above documents, are colored brown or yellow due to high electron density, and therefore have low light transmittance in the visible light region, and thus are difficult to use in fields requiring transparency. Regarding the yellowness (YI value) of the film, it is known that: for example, a polyimide obtained using a diamine having a trifluoromethyl group exhibits an extremely low yellowness (YI value) (patent document 2).

Documents of the prior art

Patent document

Patent document 1: international publication No. 2005/113647

Patent document 2: international publication No. 2019/211972

Non-patent document

Non-patent document 1: "latest polyimide-base and application- (latest ポリイミド -base 30990,", japan polyimide research institute compilation

Disclosure of Invention

Problems to be solved by the invention

However, in order to use a polyimide resin as a colorless transparent flexible substrate, in addition to mechanical properties such as transparency, excellent elongation, and breaking strength, laser peelability from the substrate is required. Particularly, recently, as the device type of TFT is changed to LTPS (low temperature polysilicon TFT), a thin film exhibiting the above properties even in a thermal history exceeding the conventional one is desired. However, the properties of known transparent polyimides are not sufficient for use as heat-resistant colorless transparent substrates for displays. Further, the present inventors confirmed that: the polyimide resin described in patent document 1 has a low linear thermal expansion coefficient, but the polyimide resin film after peeling has a large yellowness (YI value), and has problems of high residual stress, low elongation, and low breaking strength.

With respect to laser peelability, although the polyimide film described in patent document 2 exhibits excellent performance, the present inventors have confirmed that: the polyimide film described in patent document 2 exhibits a low yellowness (YI value) in a temperature range of about 350 to 400 ℃, but in a high temperature range of 430 ℃ or higher, the yellowness (YI value) is significantly deteriorated, the Haze (Haze value) is increased, and the visibility is lowered.

An object of the present invention is to solve the above problems and to provide a polyimide resin film which has low residual stress, less warpage, small yellowness (YI value) at high temperature (particularly 430 ℃ or higher), small Haze (Haze value), and excellent laser peelability from a substrate, and a method for producing the same.

Means for solving the problems

The present invention includes the following aspects.

[1] A polyimide precursor comprising (a1) a structural unit L represented by the following general formula (1) and (a2) a structural unit M represented by the following general formula (2),

{ formula (1) wherein X represents a 4-valent organic group, Y₁Represents a 2-valent organic group. }

{ formula (2) wherein X represents a 4-valent organic group, Y₂Represents a 2-valent organic group, and Z represents-NHNH-or-N ═ N-. }

Y in the above general formula (2)₂Is at least 1 kind selected from the group consisting of structures represented by the following general formulas (A-1) to (A-6),

{ formula (II) wherein R₁～R₁₃Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, a to m are each independently an integer of 0 to 4, n is an integer of 1 or more, and x represents a bonding site. }

The ratio of the amount of the structural unit M to the total amount of the structural units L and M is 0.005 to 0.5 mol%.

[2]The polyimide precursor according to the aspect 1, wherein Y is₂Is at least 1 selected from the group consisting of the structures represented by the aforementioned general formula (A-1) and the aforementioned general formula (A-6).

[3] A polyimide precursor comprising (a1) a structural unit L represented by the following general formula (1) and (a2) a structural unit M represented by the following general formula (2),

Y in the above general formula (2)₂Is as followsA structure represented by the following general formula (A-6).

{ formula (A-6), wherein R₁₃Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, m is an integer of 0 to 4, n is an integer of 1 or more, and x represents a bonding site. }

[4]The polyimide precursor according to any one of embodiments 1 to 3, wherein Y in the general formula (1)₁Is at least 1 selected from the group consisting of the structures represented by the following general formulae (A-1) to (A-5).

{ formula (II) wherein R₁～R₁₂Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, a to l each independently represents an integer of 0 to 4, and represents a bonding site. }

[5] The polyimide precursor according to any one of embodiments 1 to 4, wherein X in the general formula (1) or the general formula (2) or both is a 4-valent group derived from at least 1 selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), 4,4 '-biphenylbis (trimellitic acid monoester anhydride) (TAHQ), 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF), 3', 4,4 '-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4, 4' -oxydiphthalic anhydride (ODPA), and cyclopentanone-bisspironorbornane tetracarboxylic dianhydride (CpODA).

[6] A resin composition comprising (a) the polyimide precursor according to any one of the above embodiments 1 to 5 and (b) an organic solvent.

[7] The resin composition according to the above mode 6, further comprising at least 1 selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.

[8] The resin composition according to mode 6 or 7, wherein a polyimide resin film obtained by curing the resin composition is used for a flexible device.

[9] The resin composition according to mode 6 or 7, wherein a polyimide resin film obtained by curing the resin composition is used for a flexible display.

[10] A polyimide film obtained from the polyimide precursor according to any one of the above aspects 1 to 5 or the resin composition according to any one of the above aspects 6 to 9.

[11] A polyimide comprising a structural unit represented by the following general formula (3),

{ formula (3) } wherein X independently represents a 4-valent organic group, and Y₁And Y₂Each independently represents a 2-valent organic group, l and m are each independently an integer of 1 or more, wherein 0.005. ltoreq. m/(l + m). ltoreq.0.5 is satisfied. }

Y is the above-mentioned₂Is at least 1 selected from the group consisting of the structures represented by the following general formulae (A-1) and (A-6).

{ formula (II) wherein R₁、R₂And R₁₃Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, a, b and m are each independently an integer of 0 to 4, n is an integer of 1 or more, and x represents a bonding site. }

[12] A polyimide comprising a structural unit represented by the following general formula (3).

{ formula (3) } wherein X independently represents a 4-valent organic group, and Y₁Each independently represents a 2-valent organic group, Y₂Is a structure represented by the following general formula (A-6), wherein l and m are each independently an integer of 1 or more, and wherein 0.005. ltoreq. m/(l + m). ltoreq.0.5 is satisfied. }

(in the formula (A-6), R₁₃Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, m is each independently an integer of 0 to 4, n is an integer of 1 or more, and x represents a bonding site. )

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

a step of forming a coating film by applying the resin composition according to any one of the above aspects 6 to 9 on the surface of a support;

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

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

[14] The method for manufacturing a resin film according to aspect 13, further comprising: a step of irradiating the polyimide resin film with a laser beam from the support before the step of peeling the polyimide resin film from the support.

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

a step of forming a coating film by applying the resin composition according to any one of the above aspects 6 to 9 on the surface of a support; and

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

[16] A method for manufacturing a display substrate includes the steps of:

heating the support and the coating film to imidize a polyimide precursor contained in the coating film and 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 having the element or the circuit formed thereon from the support.

ADVANTAGEOUS EFFECTS OF INVENTION

The polyimide resin film obtained from the polyimide precursor and the resin composition according to one embodiment of the present invention has less warpage, a small yellowness (YI value) at a high temperature (particularly 430 ℃ or higher), a small Haze (Haze value), and excellent laser peelability from a substrate.

Drawings

Fig. 1 is a schematic diagram showing a structure of a top emission type flexible organic EL display, which is an example of the display of the present embodiment, at an upper portion than a polyimide substrate.

Description of the reference numerals

2a lower substrate

2b sealing substrate

25 organic EL structure

250a organic EL element emitting red light

250b organic EL element emitting green light

250c organic EL element emitting blue light

251 partition wall (Bank)

252 lower electrode (anode)

253 hole transport layer

254 light emitting layer

255 Upper electrode (cathode)

256 TFT

257 contact holes

258 interlayer insulating film

259 lower electrode

261 hollow part

Detailed Description

Hereinafter, exemplary embodiments of the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the present invention. The characteristic value described in the present application means a value measured by the method described in [ example ] or a method considered equivalent to the method by those skilled in the art, unless otherwise specified.

< polyimide precursor >

A first embodiment of the present application provides a polyimide precursor including (a1) a structural unit L represented by the following general formula (1) and (a2) a structural unit M represented by the following general formula (2).

{ wherein X represents a 4-valent organic group, and Y₁Represents a 2-valent organic group. }

{ wherein X represents a 4-valent organic group, and Y₂Represents a 2-valent organic group, and Z represents-NHNH-or-N ═ N-. }

In the present application, the organic group means a group having 1 or more carbon atoms.

In one embodiment, the ratio of the amount of the structural unit M to the total amount of the structural unit L and the structural unit M is 0.005 to 0.5 mol%. The ratio of the amount of the structural unit M mentioned here to the total amount of the structural unit L and the structural unit M is calculated by the method shown below. That is, after the polyimide precursor is depolymerized and separated into an acid component and an amine component, the polyimide precursor is separated into the amine component of the general formula (1) and the amine component of the general formula (2) by high performance liquid chromatography-mass spectrometry (hereinafter also referred to as LC/MS), the respective peak areas in the chromatogram of the photodiode array (PDA) in the detection at 300nm are obtained, and the peak area ratios thereof [ (peak area of the amine component of the general formula (2)/{ (peak area of the amine component of the general formula (1)) + (peak area of the amine component of the general formula (2) } × 100 are calculated as ratios (%).

When the above ratio is 0.005 mol% or more, the laser peelability tends to be good, and when the ratio is 0.5 mol% or less, the yellowness of the polyimide film tends to be good, and the ash after laser peeling tends to be suppressed. In the case of laser peeling, the polyimide film may burn with laser light, and the combustion residue may be ash. From the viewpoint of suppressing the yellowness, the above ratio is preferably 0.35 mol% or less, and more preferably 0.3 mol% or less. From the viewpoint of improving the laser peelability, the ratio is preferably 0.01 mol% or more, and more preferably 0.05 mol% or more.

The polyimide precursor of the first embodiment has low residual stress, less warpage, low yellowness (YI value) and excellent laser peelability from a substrate when formed into a polyimide film. In addition, the polyimide precursor according to the first embodiment has a small yellowness (YI value) and a small Haze (Haze value) in a high-temperature region when formed into a polyimide film.

(structural Unit represented by the general formula (1))

In the above general formula (1), X is a 4-valent organic group, and a plurality of X's present in the polyimide precursor are optionally the same as or different from each other. Examples of X include a 4-valent organic group derived from the following tetracarboxylic dianhydride.

Examples of the tetracarboxylic dianhydride include an aromatic tetracarboxylic dianhydride having 8 to 36 carbon atoms, an aliphatic tetracarboxylic dianhydride having 6 to 36 carbon atoms, and an alicyclic tetracarboxylic dianhydride having 6 to 36 carbon atoms. Among them, an aromatic tetracarboxylic dianhydride having 8 to 36 carbon atoms is preferable from the viewpoint of yellowness in a high-temperature region. The number of carbon atoms mentioned herein also includes the number of carbon atoms contained in the carboxyl group.

Examples of the aromatic tetracarboxylic 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 (hereinafter also referred to as DSDA), and 2, 2', 3,3 '-biphenyltetracarboxylic dianhydride, methylene-4, 4-diphthalic dianhydride, 1-ethylidene-4, 4' -diphthalic dianhydride, 2-propylidene-4, 4 '-diphthalic dianhydride, 1, 2-ethylene-4, 4' -diphthalic dianhydride, 1, 3-trimethylene-4, 4 '-diphthalic dianhydride, 1, 4-tetramethylene-4, 4' -diphthalic dianhydride, 1, 5-pentamethylene-4, 4 '-diphthalic dianhydride, 4' -oxydiphthalic dianhydride (hereinafter also referred to as ODPA), p-phenylenebis (trimellitic anhydride) (hereinafter also referred to as TAHQ), thio-4, 4 '-diphthalic dianhydride, sulfonyl-4, 4' -diphthalic dianhydride, 1, 3-bis (3, -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, 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, cyclopentanone bis-spironorbornane tetracarboxylic dianhydride (hereinafter also referred to as CpODA), 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-ethylidene-4, 4 ' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 2, 2-propylidene-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] 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 a balance of the Coefficient of Thermal Expansion (CTE), chemical resistance, glass transition temperature (Tg), and yellowness in a high-temperature region, PMDA, BPDA, DSDA, TAHQ, ODPA, CpODA are preferable, and BPDA and TAHQ are more preferable.

The polyimide precursor of the present embodiment can be obtained by using a dicarboxylic acid in addition to the tetracarboxylic dianhydride, within the range that does not impair the performance thereof. By using such a precursor, various properties such as an increase in mechanical elongation, an increase in glass transition temperature, and a decrease in yellowness can be adjusted in the obtained film. Examples of such dicarboxylic acids include dicarboxylic acids having an aromatic ring and alicyclic dicarboxylic acids. Particularly preferably at least 1 compound selected from the group consisting of aromatic dicarboxylic acids having 8 to 36 carbon atoms and alicyclic dicarboxylic acids having 6 to 34 carbon atoms. The number of carbon atoms mentioned herein also includes the number of carbon atoms contained in the carboxyl group. Among these, 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, 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-phenylene, p-phenylene, p-phenylene, p-phenylene, p-phenylene, p-p, 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, 3 ' -bis (3-carboxyphenoxy) m-terphenyl, 1, 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

and 5-aminoisophthalic acid derivatives described in International publication No. 2005/068535. When these dicarboxylic acids are actually copolymerized in the polymer, they may be used in the form of acid chlorides derived from thionyl chloride or the like, active esters, or the like.

In the above general formula (1), Y₁The organic group having a valence of 2 is preferably at least 1 of the structures represented by the following general formulae (A-1) to (A-5). As Y₁From the viewpoints of yellowness (YI value) and laser peelability in a high temperature region, the structure represented by the general formula (A-1) is preferable.

General formula (A-1):

{ formula (II) wherein R₁And R₂Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, a and b are each independently an integer of 0 to 4, and a represents a bonding site. }

Here, R₁And R₂The organic group is not limited as long as each is independently a 1-valent organic group having 1 to 20 carbon atoms or a halogen. Examples of the organic group include alkyl groups such as methyl group, ethyl group, and propyl group; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Examples of the halogen include a fluoro group. Among them, methyl groups and fluoro groups are preferable from the viewpoint of yellowness (YI value) and Haze (Haze value) in the high-temperature region.

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

General formula (A-2):

{ formula (II) wherein R₃And R₄Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, d and e are each independently an integer of 0 to 4, and a is a bonding site. }

Here, R₃And R₄The organic group is not limited as long as each is independently a 1-valent organic group having 1 to 20 carbon atoms or a halogen. 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 the yellowness (YI value) in the high temperature region.

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

General formula (A-3):

{ formula (II) wherein R₅～R₈Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, e to h are each independently an integer of 0 to 4, and a bonding site. }

Here, R₅～R₈The organic group is not limited as long as each is independently a 1-valent organic group having 1 to 20 carbon atoms or a halogen. 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 the yellowness (YI value) in the high temperature region.

Here, e to h are not limited as long as each is independently an integer of 0 to 4. Among them, an integer of 0 to 2 is preferable from the viewpoint of the yellowness (YI value) and the residual stress, and 0 is particularly preferable from the viewpoint of the yellowness (YI value) in a high temperature region.

General formula (A-4):

{ formula (II) wherein R₉And R₁₀Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, i and j are each independently an integer of 0 to 4, and a bonding site. }

Here, R₉And R₁₀The organic group is not limited as long as each is independently a 1-valent organic group having 1 to 20 carbon atoms or a halogen. 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. Wherein yellow from high temperature regionFrom the viewpoint of the degree (YI value), a methyl group is preferable.

Here, i and j are not limited as long as each is independently an integer of 0 to 4. Among them, an integer of 0 to 2 is preferable from the viewpoint of the yellowness (YI value) and the residual stress, and 0 or 1 is particularly preferable from the viewpoint of the yellowness (YI value) in a high temperature region.

General formula (A-5):

{ formula (II) wherein R₁₁And R₁₂Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, k and l are integers of 0 to 4, and x is a bonding site. }

Here, R₁₁And R₁₂The organic group is not limited as long as each is independently a 1-valent organic group having 1 to 20 carbon atoms or a halogen. Examples of the organic group include alkyl groups such as methyl group, ethyl group, and propyl group; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Examples of the halogen include a fluoro group. Among them, methyl groups and fluoro groups are preferable from the viewpoint of the yellowness (YI value) in the high temperature region.

Here, k and l are not limited as long as each is independently an integer of 0 to 4. Among them, an integer of 0 to 2 is preferable from the viewpoint of the yellowness (YI value) and the residual stress, and 0 is particularly preferable from the viewpoint of the yellowness (YI value) in a high temperature region.

The structural unit represented by the general formula (A-1) is derived from a diamine represented by the following general formula (B-1) in one embodiment.

{ formula (II) wherein R₁、R₂A and b are as defined for the general formula (A-1). }

More specifically, examples of the diamine represented by the general formula (B-1) include 4-aminophenyl-4-aminobenzoate (hereinafter, also referred to as APAB), 2-methyl-4-aminophenyl-4-aminobenzoate (hereinafter, also referred to as 2Me-APAB), 3-methyl-4-aminophenyl-4-aminobenzoate (hereinafter, also referred to as 3Me-APAB), 2-fluoro-4-aminophenyl-4-aminobenzoate (hereinafter, also referred to as 2F-APAB), 3-fluoro-4-aminophenyl-4-aminobenzoate (hereinafter, also referred to as 3F-APAB), 3-methyl-4-aminophenyl-3-methyl-4-aminobenzoate (hereinafter, also referred to as 3,3Me-APAB), etc., preferably APAB, 3Me-APAB, 3F-APAB and 3,3Me-APAB from the viewpoint of reducing the Haze (Haze value).

The structural unit represented by the general formula (A-2) is derived from a diamine represented by the following general formula (B-2) in one embodiment.

{ formula (II) wherein R₃、R₄C and d are as defined for the general formula (A-2). }

More specifically, examples of the diamine represented by the general formula (B-2) include 4,4 '-diaminodiphenyl sulfone (hereinafter, also referred to as 44DAS) and 3, 3' -diaminodiphenyl sulfone.

The structural unit represented by the general formula (A-3) is derived from a diamine represented by the following general formula (B-3) in one embodiment.

{ formula (II) wherein R₅～R₈And e to h are as defined for the general formula (A-3). }

More specifically, examples of the diamine represented by the general formula (B-3) include 9, 9-bis (aminophenyl) fluorene (hereinafter also referred to as BAFL), 9-bis (4-amino-3-methylphenyl) fluorene, 9-bis (4-amino-3-fluorophenyl) fluorene, 9-bis (4-hydroxy-3-aminophenyl) fluorene, and 9, 9-bis [4- (4-aminophenoxy) phenyl ] fluorene, and 1 or more selected from these can be preferably used.

The structural unit represented by the general formula (A-4) is derived from a diamine represented by the following general formula (B-4) in one embodiment.

{ formula (II) wherein R₉、R₁₀I and j are as defined for the general formula (A-4). }

More specifically, 2' -bis (trifluoromethyl) benzidine (hereinafter also referred to as TFMB) is exemplified as the diamine represented by the general formula (B-4).

The structural unit represented by the general formula (A-5) is derived from a diamine represented by the following general formula (B-5) in one embodiment.

{ formula (II) wherein R₁₁、R₁₂K and l are as defined for the general formula (B-5). }

More specifically, examples of the diamine represented by the general formula (B-5) include 4, 4' -diaminobenzanilide (hereinafter also referred to as DABA).

(structural Unit represented by the general formula (2))

In the general formula (2), X may have the same structure as that exemplified for X in the general formula (1).

In the above general formula (2), Y₂It is preferably at least 1 selected from the group consisting of the structures represented by the general formulae (A-1) to (A-5) described above for the general formula (1) and the structure represented by the following general formula (A-6).

{ formula (II) wherein R₁₃Independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, m is an integer of 0 to 4, n is an integer of 1 or more, and x represents a bonding site. }

Here, R₁₃The organic group is not limited as long as each is independently a 1-valent organic group having 1 to 20 carbon atoms or a halogen. Examples of the organic group include alkyl groups such as methyl group, ethyl group, and propyl group; trifluoromethyl, etcA halogen-containing group; alkoxy groups such as methoxy and ethoxy. Examples of the halogen include a fluoro group. Among them, methyl groups and fluoro groups are preferable from the viewpoint of the yellowness (YI value) in the high temperature region.

Here, m is not limited as long as it is an integer of 0 to 4. Among them, an integer of 0 to 2 is preferable from the viewpoint of yellowness (YI value) and laser peelability, and 0 is particularly preferable from the viewpoint of yellowness (YI value) in a high temperature region.

Here, n is an integer of 1 or more, preferably an integer of 1 to 4. Among them, an integer of 1 to 2 is preferable from the viewpoint of YI and laser peelability, and 1 is particularly preferable from the viewpoint of yellowness (YI value) in a high temperature region.

As Y₂From the viewpoints of yellowness (YI value) and laser peelability in a high-temperature region, at least 1 selected from the group consisting of structures represented by the general formulae (A-1) and (A-6) is preferable, or a structure represented by the general formula (A-1) is preferable, or a structure represented by the general formula (A-6) is preferable.

In the general formula (2), Z is a bond represented by — NHNH — or — N ═ N-, and the polyimide precursor may contain either one or both of them. Among them, from the viewpoint of yellowness (YI value) in the high temperature region, it is preferable that — N ═ N-bond. In general, azo compounds having an — N ═ N-bond are known to undergo photoisomerization by light, and it is considered that: the azo structure is excited by laser energy irradiated during laser lift-off, and the laser lift-off property is improved. Therefore, the absorbance in the vicinity of the wavelength (for example, 308nm) of the laser ablation generally used is important. The structure represented by the general formula (2) preferably has good absorbance at the wavelength of the laser ablation as described above. As described above, the content of the structure represented by the general formula (2) is a value obtained from a PDA chromatogram measured by an LC/MS method equipped with a 300nm detector. Since the-NHNH-bond is reduced to the-N ═ N-bond during thermal imidization, it can contribute to improvement of laser peelability, similarly to the-N ═ N-bond.

In the general formula (2), as Y₂and-Y in the case of having a structural unit represented by the above general formula (A-6)₂-Z-Y₂The structure of (E) is derived from a diamine represented by the following general formula (B-6) in one embodiment.

{ formula (II) wherein R₁₃M and n are as defined for the general formula (A-6). }

More specifically, examples of the diamine represented by the general formula (B-6) include 4, 4' -azodiphenylamine (hereinafter also referred to as AzBz).

The diamines used to form the structural unit represented by the general formula (2) are not particularly limited, and diamines represented by the following formulas (C-1) to (C-4) can be exemplified.

(bis (4, 1-phenylene) bis (4-aminobenzoate) diazene-1, 2-diyl, Azo-APAB)

(bis (2-fluoro-4, 1-phenylene) bis (4-aminobenzoate) diazene-1, 2-diyl, Azo-2F-APAB)

(bis (3-fluoro-4, 1-phenylene) bis (4-aminobenzoate) diazene-1, 2-diyl, Azo-3F-APAB)

(bis (3-methyl-4, 1-phenylene) bis (4-aminobenzoate) diazene-1, 2-diyl, Azo-3Me-APAB)

The weight average molecular weight (Mw) of the polyimide precursor of the present embodiment is preferably 10,000 to 300,000, and particularly preferably 30,000 to 200,000. When the weight average molecular weight is 10,000 or more, mechanical properties such as elongation and breaking strength are excellent, the residual stress is low, and YI is low. If the weight average molecular weight is 300,000 or less, 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 coating property of the resin composition can be improved. In the present application, the weight average molecular weight is a value obtained as a standard polystyrene equivalent value by using gel permeation chromatography (hereinafter, also referred to as GPC).

The content of molecules having a molecular weight of less than 1,000 in the polyimide precursor of the present embodiment is preferably less than 5% by mass, more preferably less than 1% by mass, with respect to the total amount of the polyimide precursor. A polyimide film formed from a resin composition obtained using such a polyimide precursor has a low residual stress, and an inorganic film formed on the polyimide film has a low Haze (Haze value). The content of molecules having a molecular weight of less than 1,000 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.

< polyimide >

A second embodiment of the present application provides a polyimide comprising a structural unit represented by the following general formula (3).

{ wherein, X independently represents a 4-valent organic group, and Y₁And Y₂Each independently represents a 2-valent organic group, l and m are each independently an integer of 1 or more, wherein 0.005. ltoreq. m/(l + m). ltoreq.0.5 is satisfied. }

In the general formula (3), X, Y₁And Y₂Can be compared with the aforementioned X, Y in the general formulae (1) and (2)₁And Y₂The same applies to the example of (1).

As X in the general formula (3), PMDA, BPDA, DSDA, TAHQ, ODPA, and CpODA are preferable, and BPDA and TAHQ are more preferable, from the viewpoint of the balance of CTE, chemical resistance, Tg, and yellowness (YI value) in a high temperature region.

Y in the general formula (3)₁Can be used with Y in the general formula (1)₁The exemplified groups are the same, and may be, for example, 2-valent organic groups represented by the general formulae (A-1) to (A-5) and may be derived from diamines having structures represented by the general formulae (B-1) to (B-5). Furthermore, Y₂And Z may be substituted with Y as in the general formula (2)₂The same as for Z, e.g. Y₂May be a 2-valent organic group represented by the general formulae (A-1) to (A-6) — Y₂-Z-Y₂The structure of (E) may be derived from a diamine represented by the general formula (B-6).

Y in the general formula (3)₂Preferably at least 1 selected from the group consisting of the structures represented by the general formulae (A-1) and (A-6), and more preferably the structure represented by the general formula (A-6).

The polyimide precursor of the first embodiment and the polyimide of the second embodiment may be used in addition to the diamines represented by the general formulae (B-1) to (B-6) and (C-1) to (C-4) as described above, in such a range that the elongation, strength, stress, laser peelability, yellowness, 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-bis (3-aminophenoxy) benzene, 3-bis (4-aminobenzophenone, 3-diaminodiphenyl sulfide, 3,4 ' -diaminodiphenyl sulfide, 3 ' -diaminodiphenyl sulfide, 3,4 ' -diaminodiphenyl sulfide, 3,4 ' -diaminodiphenyl, 3 ' -diaminodiphenyl, 4 ' -diaminodiphenyl, 3 ' -diaminodiphenyl, and the like, 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 these 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 (specifically, polyamic acid) according to the present embodiment can be synthesized by subjecting tetracarboxylic dianhydride, a diamine (for example, APAB) used for the structural unit represented by the general formula (1), and a diamine (for example, AzBz) used for the structural unit represented by the general formula (2) to a polycondensation reaction. The reaction is preferably carried out in a suitable solvent. Specifically, for example, a method in which a predetermined amount of APAB and AzBz is dissolved in a solvent, and then a predetermined amount of tetracarboxylic dianhydride is added to the resulting diamine solution and stirred can be mentioned.

In the diamine component, the molar ratio of the diamine used for the structural unit represented by the general formula (1) to the diamine used for the structural unit represented by the general formula (2) is not limited as long as the molar ratio is 0.005 to 0.5 mol% (the number of moles of the structural unit represented by the general formula (2)/[ (the number of moles of the structural unit represented by the general formula (1) + (the number of moles of the structural unit represented by the general formula (2)). In the diamine component, if the diamine used in the structural unit represented by the general formula (2) is 0.005 mol% or more, the laser peelability tends to be good, and if it is 0.5 mol% or less, the yellowness (YI value) of the polyimide film tends to be good and ash after laser peeling tends to be suppressed. When the diamine used in the structural unit represented by the general formula (1) is 99.5 mol% or more, the residual stress of the polyimide film tends to be good. (the number of moles of the structural unit represented by the general formula (2)/[ (the number of moles of the structural unit represented by the general formula (1) + (the number of moles of the structural unit represented by the general formula (2)) ] is preferably 0.0075 to 0.3 mol%, more preferably 0.009 to 0.1 mol%.

From the viewpoint of controlling the thermal linear expansion coefficient, residual stress, elongation, and yellowness (YI value) of the obtained resin film to desired ranges, the ratio (molar ratio) of the tetracarboxylic dianhydride component to the diamine component in synthesizing the polyimide precursor of the present embodiment is preferably in the range of 100:90 to 100:110 (0.90 to 1.10 parts by mole of diamine relative to 1 part by mole of tetracarboxylic dianhydride), and more preferably in the range of 100:95 to 100:105 (0.95 to 1.05 parts by mole of diamine relative to 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 is used, the larger the molecular weight of the polyamic acid can be.

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, the above purity is sufficient as long as the acid dianhydride component or diamine component has the above purity as a whole, but it is preferable that all the types of acid dianhydride components and diamine components used have the above purity, respectively. The other component may contain a diamine for forming the structural unit M represented by the general formula (2). On the other hand, it is preferable that impurities other than the diamine for forming the structural unit M represented by the general formula (2) are not contained.

The reaction solvent is not particularly limited as long as it is a solvent capable of dissolving the tetracarboxylic dianhydride component, the diamine component, and the resulting polyamic acid and obtaining a high molecular weight polymer. Specific examples of such a solvent include aprotic solvents, phenol solvents, ether solvents, glycol solvents, and the like. Specific examples thereof include: examples of the aprotic solvent include amide solvents such as N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N-methylcaprolactam, 1, 3-dimethylimidazolidinone, tetramethylurea, EQUAMIDE M100 (trade name: manufactured by KANGO CORPORATION), EQUAMIDE B100 (trade name: manufactured by KANGO CORPORATION);

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

phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphoramide;

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 solvent include phenol, o-cresol, m-cresol, p-cresol, 2, 3-xylenol, 2, 4-xylenol, 2, 5-xylenol, 2, 6-xylenol, 3, 4-xylenol, and 3, 5-xylenol;

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 for synthesizing the polyamic acid at normal pressure is preferably 60 to 300 ℃, more preferably 140 to 280 ℃, and particularly preferably 170 to 270 ℃. If the boiling point of the solvent is higher than 300 ℃, the drying process takes a long time. On the other hand, if the boiling point of the solvent is less than 60 ℃, a uniform film may not be obtained in some cases, for example, the surface of the resin film may be roughened or bubbles may be mixed into the resin film in the drying step.

In this manner, from the viewpoint of solubility and edge exclusion at the time of coating, a solvent having a boiling point of 170 to 270 ℃ is preferred, and a solvent having a vapor pressure of 250Pa or less at 20 ℃ is more preferred. More specifically, 1 or more selected from the group consisting of N-methyl-2-pyrrolidone and γ -butyrolactone is preferably used. The moisture content in the solvent is preferably 3,000 mass ppm or less. These solvents may be used alone or in combination of 2 or more.

As described above, the content of molecules having a molecular weight of less than 1,000 in the polyimide precursor of the present embodiment is preferably less than 5% by mass. The reason why molecules having a molecular weight of less than 1,000 are present in the polyimide precursor is considered to be related to the moisture content of the solvent used in the synthesis. Namely, it can be considered that: part of the acid anhydride groups of the acid dianhydride monomer are hydrolyzed by water to form carboxyl groups, and the carboxyl groups remain in a low molecular weight state without increasing the molecular weight. Therefore, the amount of water in the solvent used in the polymerization reaction is preferably as small as possible. From this viewpoint, the water content of the solvent is preferably 3,000 mass ppm or less, and more preferably 1,000 mass ppm or less.

It can be considered that: the water content of the solvent is related to the grade of the solvent used (dehydration grade, general grade, etc.), the solvent container (bottle, 18L tank, canister, etc.), the storage state of the solvent (whether rare gas is sealed, etc.), the time from unsealing to use (whether to use immediately after unsealing or whether to reuse for a certain time after unsealing, etc.), and the like. Further, it can be considered that: the present invention also relates to the replacement of a rare gas in a reactor before synthesis, whether or not a rare gas is circulated during synthesis, and the like. Therefore, it is recommended to use a high-purity product as a raw material in the synthesis of the polyimide precursor, use a solvent having a small water content, and take measures to prevent water from the environment from being mixed into the system before and during the reaction.

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

The reaction temperature for synthesizing 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. When the polymerization time is 1 hour or more, a polyimide precursor having a high polymerization degree is formed, and when the polymerization time is 100 hours or less, a polyimide precursor having a uniform polymerization degree can be obtained.

In a preferred embodiment of the present embodiment, the polyimide precursor has the following characteristics.

The resin obtained by imidizing a polyimide precursor has a yellowness (YI value) of 30 or less at a film thickness of 10 μm by applying a solution obtained by dissolving the polyimide precursor 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 ℃) for 1 hour in a nitrogen atmosphere (e.g., in nitrogen having an oxygen concentration of 2,000 mass ppm or less).

The residual stress of a resin obtained by imidizing a polyimide precursor is 25MPa or less by applying a solution obtained by dissolving the polyimide precursor in a solvent (for example, N-methyl-2-pyrrolidone) to the surface of a support, and then heating the solution at 300 to 550 ℃ (for example, 430 ℃) in a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2,000 mass ppm or less) (for example, for 1 hour).

In a preferred embodiment of the present embodiment, a part of the polyimide precursor may be imidized (i.e., partially imidized). The imidization ratio in this case is preferably 80% or less, more preferably 50% or less. The partial imidization can be produced by heating the above polyimide precursor and dehydrating the same for ring closure. The heating for partial imidization may be carried out at a temperature of preferably 120 to 200 ℃, more preferably 150 to 180 ℃, preferably for 15 minutes to 20 hours, more preferably for 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 and heating the mixture to esterify a part or all of the carboxylic acid and using the esterified carboxylic acid as the polyimide precursor of the present embodiment, a resin composition having improved viscosity stability during storage at room temperature can also be obtained. These ester-modified polyamic acids can also be obtained by a method in which the acid dianhydride component is reacted with 1 equivalent of a monohydric alcohol and a dehydration-thickening agent such as thionyl chloride or dicyclohexylcarbodiimide in this order with respect to the acid anhydride group, and then the reaction product is condensed with a diamine component.

< resin composition >

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

[ (a) polyimide precursor ]

The polyimide precursor (a) in the resin composition may be the polyimide precursor of the present application described above. The proportion of the polyimide precursor (preferably polyamic acid) (a) in the resin composition 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.

[ (b) organic solvent ]

(b) The organic solvent is not particularly limited as long as it can dissolve the polyimide precursor (a) and other components optionally used. As such (b) organic solvent, the solvent described above as a solvent that can be used in the synthesis of the polyimide precursor (a) can be used. Preferred organic solvents are also 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 also preferable to add the organic solvent (b) after adjusting the composition and amount thereof so that the viscosity (25 ℃) of the resin composition is 500 to 100,000 mPas.

[ other Components ]

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.

As the skeleton of the polyimide precursor, the skeletons as described above in the first embodiment and the second embodiment can be illustrated. In one embodiment, the skeleton of the polyimide precursor may be a skeleton having a structural unit represented by the general formula (1).

[ (c) surfactant ]

The resin composition of the present embodiment can improve the coatability of the resin composition by containing a surfactant. 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. Examples of these may be: 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 industries, Ltd.), SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (trade name; manufactured by Dow Corning Silicone Co., Ltd.), SILWET L-77, L-7001, FZ-2105, FZ-210, FZ-2154, FZ-2164, FZ-2166, L-7604 (trade name; manufactured by Yue Cork., Japan), DBE-814, DBE-224, DBE-621, CMS-66, CMS-222, KF-352A, KF-354L, KF-355A, KF-600, CMS-A, KF-39600, DBE-821, DBE-712(Gelest), BYK-307, BYK-30, BYK-378, BYK-333 (trade name, BYK-Chemie Japan Co., Ltd.), GLANOL (trade name, Kyoho chemical Co., Ltd.), etc.;

examples of the fluorine-based surfactant include Megafac F171, F173, R-08 (trade name, manufactured by Dainippon ink chemical industries Co., Ltd.), Fluorad FC4430, FC4432 (trade name, manufactured by Sumitomo 3M Co., Ltd.);

examples of the other nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene octylphenyl ether.

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

The resin composition according to the present embodiment may contain 0.01 to 20 parts by mass of an alkoxysilane compound per 100 parts by mass of the polyimide precursor (a) in order to provide a resin film having sufficient adhesion between supports in the production process of flexible devices and the like. By setting the content of the alkoxysilane compound to 0.01 part by mass or more per 100 parts by mass of the polyimide precursor, good adhesion to the support can be obtained. In addition, the content of the alkoxysilane compound is preferably 20 parts by mass or less from the viewpoint of storage stability of the resin composition. The content of the alkoxysilane compound is more preferably 0.02 to 15 parts by mass, still more preferably 0.05 to 10 parts by mass, and particularly preferably 0.1 to 8 parts 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 in the above-described adhesiveness, the coatability of the resin composition can be further improved (stripe unevenness can be suppressed), and the oxygen concentration dependency of the yellowness (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) silane, di (n-butyl) triethoxysilane, tri (n-butyl) trimethoxysilane, tri (n-butyl) triethoxysilane, tri (n-butyl) alkoxysilane, and the like, Diphenylsilanediol, dimethoxydiphenylsilane, diethoxydiphenylsilane, dimethoxybis (p-tolyl) silane, triphenylsilanol, and the like, and preferably 1 or more selected from them are used.

The method for producing the resin composition of the present embodiment is not particularly limited. The following method can be used, for example.

When the solvent used in the synthesis of 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 (b) 1 or more of the organic solvent and other components to the polyimide precursor at a temperature ranging from room temperature (25 ℃) to 80 ℃ as necessary, and then stirring and mixing the mixture. The stirring and mixing may be carried out by using an appropriate device such as a Three one motor (manufactured by Xindong chemical Co., Ltd.) having a stirring blade, a rotating and revolving stirrer, or the like. Further, 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 resin composition can also be prepared by removing the solvent from the synthesized polyimide precursor solution by an appropriate method such as reprecipitation or solvent distillation to separate the polyimide precursor (a), adding the organic solvent (b) and other components as needed at a temperature ranging from room temperature to 80 ℃ and mixing them with stirring.

After the resin composition is prepared as described above, a part of the polyimide precursor may be subjected to dehydration imidization to such an extent that the polymer is not precipitated by heating the composition solution at 130 to 200 ℃ for, for example, 5 minutes to 2 hours. Here, the imidization ratio can be controlled by controlling the heating temperature and the heating time. The polyimide precursor is partially imidized, whereby 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 balancing the solubility of the polyimide precursor in the resin composition solution and the storage stability of the solution.

The water content of the resin composition of the present embodiment is preferably 3,000 mass ppm or less. From the viewpoint of viscosity stability during storage of the resin composition, the water content of the resin composition is more preferably 1,000 mass ppm or less, and still more preferably 500 mass ppm or less. The water content of the resin composition is preferably small, and may be, for example, 10 mass ppm or more or 100 mass ppm or more from the viewpoint of easiness of production of the resin composition.

The resin composition of the present embodiment has a solution viscosity of preferably 300 to 200,000 mPas, more preferably 2,000 to 100,000 mPas, and particularly preferably 3,000 to 30,000 mPas at 25 ℃. The solution viscosity can be measured by using an E-type viscometer (VISCONICEHD, manufactured by eastern industries). If the solution viscosity is less than 300 mPas, the coating becomes difficult when forming a film, and if it is more than 200,000 mPas, the stirring becomes difficult when synthesizing.

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 obtained by imidizing a polyimide precursor contained in a coating film having a yellowness (YI value) of 30 or less at a film thickness of 10 μm is obtained by applying the resin composition to the surface of a support to form the 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 2,000 mass ppm or less).

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 2,000 mass ppm or less), whereby the residual stress of a resin film obtained by imidizing a polyimide precursor contained in the coating film is 25MPa or less.

The polyimide resin film obtained by curing the polyimide precursor and 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, and is particularly suitable for use in a flexible device or a flexible display. Specifically, the method can be used for forming a substrate of a Thin Film Transistor (TFT), a substrate of a color filter, a substrate of a transparent conductive film (ITO, Indium Tin Oxide), or the like.

The polyimide 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 process for manufacturing a display device 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 polyimide precursor.

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

The resin film of the present embodiment is characterized by comprising the following steps: a step (coating step) of forming a coating film by coating the resin composition on the surface of the support; a step (heating step) of heating the support and the coating film to imidize a polyimide precursor contained in the coating film and form a polyimide resin film; 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 to withstand the heating temperature in the subsequent step and has good releasability. For example, a glass (e.g., alkali-free glass) substrate;

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;

metal substrates of stainless steel, alumina, copper, nickel, and the like.

The film-shaped polyimide molded body is preferably formed of, for example, a glass substrate, a silicon wafer, or the like, and the film-shaped or sheet-shaped polyimide molded body is preferably formed of, for example, a support body made of PET (polyethylene terephthalate), OPP (oriented polypropylene), or the like.

As the coating method, coating methods such as a blade coater, an air knife coater, a roll coater, a spin coater, a flow coater, a die coater, a bar coater, and the like; coating methods such as spin coating, spray coating, dip coating and 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 1,000 μm. The coating step is performed at room temperature, but the resin composition may be heated in a range of 40 to 80 ℃ for the purpose of reducing viscosity and improving workability.

The drying step may be performed after the coating step, or the subsequent heating step may be performed without the drying step. This drying step is performed for the purpose of removing the organic solvent. In the drying step, for example, a heating plate, a box dryer, a conveyor type dryer, or the like 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, and more preferably for 3 minutes to 1 hour.

In the above manner, a coating film containing a polyimide precursor is formed on the 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 imidization of the polyimide precursor in the coating film to obtain a film made of polyimide.

The heating step can be performed using, for example, an inert gas oven, a hot plate, a box dryer, a conveyor type dryer, or the like. 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 yellowness (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 500 ℃, and more preferably 300 to 450 ℃. If the temperature is 250 ℃ or higher, imidization becomes sufficient, and if the temperature is 500 ℃ 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 2,000 mass ppm or less, more preferably 100 mass ppm or less, and still more preferably 10 mass ppm or less, from the viewpoint of transparency and yellowness (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 2,000 ppm by mass or less.

After the heating step, a peeling step of peeling the resin film from the support is required depending on the use and purpose of the polyimide resin film. 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 embodiments (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 interface between the support and the polyimide resin film is abraded by irradiating the structure with laser light from the support side, thereby peeling the polyimide resin. 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. 2007-512568, Japanese Kohyo publication No. 2012-511173, and the like).

(2) A method in which a release layer is formed on a support before a resin composition is applied to the support, and thereafter a structure comprising a polyimide resin film/release layer/support is obtained, and the polyimide resin film is peeled. Examples of the method of using PARYLENE (registered trademark, manufactured by PARYLENE contract, japan) or tungsten oxide as the release layer; examples of the method include a method using a release agent such as a vegetable oil-based, silicone-based, fluorine-based or aldehyde acid-based release agent (see, for example, jp 2010-67957 a, jp 2013-179306 a, etc.).

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

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

(4) In the method described above, after a structure comprising a polyimide resin film/a support is obtained, an adhesive film is attached to the surface of the polyimide resin film, the adhesive film/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 refractive index difference, yellowness (YI value) and elongation of the front-side back side of the obtained polyimide resin film, and the method (1) is more suitable from the viewpoint of the refractive index difference of the front-side back side of the obtained polyimide resin film.

When copper is used as the support in the method (3), the obtained polyimide resin film tends to have a large yellowness (YI value) and a small elongation. This is considered to be the influence 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 100 μm, and more preferably 5 to 20 μm.

The resin film of the present embodiment may have a yellowness index (YI value) of 30 or less at a film thickness of 10 μm. The residual stress may be 25MPa or less. In particular, the yellowness index (YI value) at a film thickness of 10 μm may be 30 or less, and the residual stress may be 25MPa or less. For example, the polyimide precursor of the present invention can be imidized in a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2,000 ppm by mass or less), preferably at 300 to 550 ℃, more preferably at 350 to 450 ℃.

< layered product >

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

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

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

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

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

More detailed description will be given below.

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 process 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 actually exhibit 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 properties (particularly, yellowness and elongation) of the polyimide film tend to be lowered by these thermal histories, and when it exceeds 400 ℃, the yellowness and elongation particularly tend to be lowered. However, the polyimide film obtained from the polyimide precursor of the present invention has little decrease in yellowness and elongation in a high temperature region of 400 ℃ or higher, and can be suitably used in such a region.

Further, in the present embodiment, a laminate including an LTPS (low temperature polysilicon TFT) layer and a polyimide thin film layer including a polyimide represented by the following general formula (3) can be provided.

As a method for producing the laminate, an LTPS layer can be formed by producing a laminate including the support and a polyimide resin film formed of the resin composition on the surface of the support, 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 by an excimer laser or the like. Thereafter, the glass and the polyimide film are peeled off by laser peeling or the like, whereby the laminate can be obtained.

The process adaptability of this annealing treatment was confirmed by performing an annealing treatment at 450 ℃ using a laminate in which a SiOx film was formed on a polyimide resin film (see < inorganic film/polyimide laminate annealing evaluation > in the following [ example ]). From the viewpoint of satisfactory evaluation of the annealing, the ratio of the amount of the structural unit M to the total amount of the structural unit L and the structural unit M is preferably 0.5% or less, and more preferably 0.1% or less. The reason why the annealing evaluation is more favorable is not clear as the ratio of the structural unit M is smaller, and it is considered that: this is because the azo bond (mainly present at the terminal) contained in the polyimide precursor is decomposed during the annealing treatment, and gas is generated.

The laminate comprising an LTPS (low temperature polysilicon TFT) layer and a polyimide thin film layer comprising a polyimide represented by the general formula (3) is less likely to peel off and swell after a thermal cycle test, and is less likely to warp a substrate.

Further, if the residual stress generated between the flexible substrate and the polyimide resin film is high, the laminate composed of the two may expand in the TFT process at high temperature and then contract 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, since the glass substrate has a smaller thermal expansion coefficient than resin, 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 glass substrates to 25MPa or less, and therefore can be suitably used for forming a flexible display.

Further, the polyimide film of the present embodiment can have a yellowness index (YI value) of 30 or less when the film thickness is 10 μm, and can be easily peeled off from a glass substrate or the like by an excimer laser or the like, and therefore, the yield in the production of a flexible display can be improved.

By setting the yellowness index (YI value) to 30 or less, a flexible substrate can be produced without degrading the image quality when a display is produced. The yellowness (YI value) is more preferably 18 or less, and particularly preferably 16 or less.

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

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

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

a step (heating step) of heating the support and the coating film to imidize a polyimide precursor contained in the coating film and 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 can be suitably used in applications in which the use is limited due to the yellow color of the conventional polyimide film, particularly in applications such as a colorless transparent substrate for a flexible display and a protective film for a color filter. Further, the film can be used in fields where colorless transparency and low birefringence are required, such as protective films, light diffusing sheets and coating films in TFT-LCDs, etc. (for example, interlayers, gate insulating films, liquid crystal alignment films, etc. of TFT-LCDs), ITO substrates for touch panels, and cover covers for smart phones, instead of resin substrates. By applying the polyimide of the present embodiment to a liquid crystal alignment film, a TFT-LCD having a high aperture ratio and a high contrast ratio can be manufactured.

Hereinafter, a method for manufacturing a display and a laminate will be described as an example of the use of the polyimide film of the present embodiment.

< method for producing display >

The method for manufacturing a display device of the present embodiment includes the steps of: a coating step of coating the resin composition of the present embodiment on the surface of the support; a film forming step of heating the resin composition to form a polyimide resin film; a device forming step of forming a device on the polyimide resin film; and a peeling step of peeling the polyimide resin film on which the element is formed from the support.

Example of manufacturing Flexible organic EL display

The organic EL structure 25 of fig. 1 will be described. In the organic EL structure 25, for example, organic EL elements 250a emitting red light, organic EL elements 250b emitting green light, and organic EL elements 250c emitting blue light are arranged in a matrix with 1 unit, and light emitting regions of the organic EL elements are defined by partition walls (banks) 251. Each organic EL element is composed of a lower electrode (anode) 252, a hole transport layer 253, a light-emitting layer 254, and an upper electrode (cathode) 255. A plurality of TFTs 256 (selected from Low Temperature Polysilicon (LTPS), metal oxide semiconductor (IGZO, etc.)) for driving the organic EL elements, an interlayer insulating film 258 having a contact hole 257, and a lower electrode 259 are provided on the lower substrate 2a indicating a CVD multilayer film (multi-barrier layer) formed of silicon nitride (SiN) or silicon oxide (SiO). The organic EL elements are sealed in the sealing substrate 2b, and a hollow portion 261 is formed between each organic EL element and the sealing substrate 2 b.

The manufacturing process of the flexible organic EL display comprises the following steps: a step of forming a polyimide film on a glass substrate support and forming the organic EL substrate shown in fig. 1 on the polyimide film; a step of manufacturing a sealing substrate; an assembly step of bonding the two substrates; and a peeling step of peeling the organic EL display produced on the polyimide film from the glass substrate support.

The organic EL substrate manufacturing step, the sealing substrate manufacturing step, and the assembling step may employ known manufacturing steps. The following examples are illustrative, but not limiting. The peeling step is the same as the above-described step of peeling the polyimide film.

For example, referring to fig. 1, a polyimide film is first formed on a glass substrate support by the above-described method, a multi-barrier layer (lower substrate 2a in fig. 1) having a multilayer structure including silicon nitride (SiN) and silicon oxide (SiO) is formed on the polyimide film by CVD or sputtering, and a metal wiring layer for driving TFTs is formed on the multi-barrier layer using a photoresist or the like. An active buffer layer such as SiO is formed on the upper portion thereof by CVD, and a TFT device (TFT 256 in fig. 1) such as metal oxide semiconductor (IGZO) or Low Temperature Polysilicon (LTPS) is formed on the upper portion thereof. After the TFT substrate for a flexible display is manufactured, an interlayer insulating film 258 including a contact hole 257 is formed using a photosensitive acrylic resin or the like. An ITO film is formed by sputtering or the like, and the lower electrode 259 is formed to match the TFT.

Next, after forming the partition walls (banks) 251 with photosensitive polyimide or the like, the hole transport layer 253 and the light-emitting layer 254 are formed in each space defined by the partition walls. Further, an upper electrode (cathode) 255 is formed so as to cover the light-emitting layer 254 and the partition walls (banks) 251. Thereafter, an organic EL substrate is produced by depositing an organic EL material emitting red light (corresponding to the organic EL element 250a emitting red light in fig. 1), an organic EL material emitting green light (corresponding to the organic EL element 250b emitting green light in fig. 1), and an organic EL material emitting blue light (corresponding to the organic EL element 250c emitting blue light in fig. 1) by a known method using a fine metal mask or the like as a mask. The organic EL substrate is sealed with a sealing film or the like (sealing substrate 2b in fig. 1), and a device on the upper side of the polyimide substrate is peeled from the glass substrate support by a known peeling method such as laser peeling, whereby a top emission type flexible organic EL display can be manufactured. When the polyimide of this embodiment is used, a bottom-view (see through) type flexible organic EL display can be manufactured. In addition, a bottom emission type flexible organic EL display can also be manufactured by a known method.

< example of manufacturing of Flexible liquid Crystal display >

A flexible liquid crystal display can be manufactured using the polyimide film of this embodiment mode. As a specific manufacturing method, a polyimide film is manufactured on a glass substrate support by the above-described method, and a TFT substrate formed of, for example, amorphous silicon, a metal oxide semiconductor (IGZO or the like), and low-temperature polysilicon is manufactured by using the above-described method. Separately, a polyimide film is formed on the glass substrate support in accordance with the coating step and the film forming step of the present embodiment, and a color filter glass substrate (CF substrate) provided with the polyimide film is formed by using a color resist or the like in accordance with a known method. A sealing material containing thermosetting epoxy resin or the like is applied by screen printing to one of the TFT substrate and the CF substrate in a frame-like pattern in which a portion of the liquid crystal injection port is missing, and the other substrate has a diameter corresponding to the thickness of the liquid crystal layer and is dispersed with spherical spacers made of plastic or silicon dioxide.

Then, the TFT substrate and the CF substrate are bonded to each other, and the sealing material is cured by emission. Next, a liquid crystal material is injected into a space surrounded by the TFT substrate, the CF substrate, and the sealing material by a reduced pressure method, a thermosetting resin is applied to the liquid crystal injection port, and the liquid crystal material is sealed by heating, thereby forming a liquid crystal layer. Finally, the glass substrate on the CF side and the glass substrate on the TFT side are peeled off at the interface between the polyimide film and the glass substrate by a laser peeling method or the like, whereby a flexible liquid crystal display can be manufactured.

< method for producing laminate >

The method for producing a laminate according to the present embodiment includes the steps of: a coating step of coating the resin composition of the present embodiment on the surface of the support; a film forming step of heating the resin composition to form a polyimide resin film; and a device forming step of forming a device on the polyimide resin film.

Examples of the element in the laminate include those exemplified in the production of the flexible device. As the support, for example, a glass substrate can be used. Preferred specific steps of the coating step and the film forming step are the same as those described for the above-described method for producing a polyimide film. In the element forming step, the element is formed on a polyimide resin film as a flexible substrate formed on a support. Thereafter, the polyimide resin film and the element can be peeled from the support in an optional peeling step.

The polyimide precursor of the present embodiment and the resin film and the laminate produced using the polyimide precursor can be 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, but these 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.

< measurement of weight average molecular weight and number average molecular weight >

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

As the solvent, N-dimethylformamide (manufactured by Fuji film and Wako pure chemical industries, for high performance liquid chromatography, and obtained by adding and dissolving 24.8mmol/L of lithium bromide monohydrate (manufactured by Fuji film and Wako pure chemical industries, purity: 99.5%) and 63.2mmol/L of phosphoric acid (manufactured by Fuji film and Wako pure chemical industries, for high performance liquid chromatography) immediately before the measurement was used. A standard curve for calculating the weight average molecular weight was prepared using standard polystyrene (Easical Type PS-1, manufactured by Agilent Technologies).

The device comprises the following steps: HLC-8220GPC (manufactured by Tosoh corporation)

Column: tsk gel Super HM-H (manufactured by Tosoh corporation)

Flow rate: 0.5 mL/min

Column temperature: 40 deg.C

A detector: UV-8220 (UV-Vis: UV-VIS absorptiometer, manufactured by Tosoh corporation)

< 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. Thereafter, the oxygen concentration in the chamber was adjusted to 10 ppm by mass or less using a vertical curing furnace (model name: VF-2000B, manufactured by Koyo Lindberg Co., Ltd.), and heat curing treatment (curing treatment) was performed at 430 ℃ for 1 hour to produce a silicon wafer having a polyimide resin film with a thickness of 10 μm after curing.

The amount of warpage of the wafer was measured using a residual stress measuring apparatus (model name: FLX-230, manufactured by Tencor Co., Ltd.) to evaluate the residual stress generated between the silicon wafer and the resin film.

Very good: 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 25MPa or less (evaluation of residual stress "good")

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

< evaluation of yellowness (YI value) and Haze (Haze value) >

In the same manner as the < evaluation of residual stress > described above, a polyimide resin film was formed on a wafer previously vapor-deposited with alumina. Thereafter, the wafer was immersed in a dilute aqueous hydrochloric acid solution, and the polyimide resin film was peeled off, thereby obtaining a resin film.

The obtained polyimide resin film was measured for yellowness (YI value) and Haze (Haze value) (film thickness converted to 10 μm) using a D65 light source, manufactured by Nippon Denshoku industries Co., Ltd. (Spectrotometer: SE 600).

< method for evaluating content (ratio of structural unit M to total of structural unit L and structural unit M) >

With respect to the resin composition prepared in the synthesis example,

adjusting the concentration to 1.0 wt%, adding appropriate amount of water, and heating at 80 deg.C for 3 days to depolymerize acid component and amine component to obtain acid monomer and amine monomer;

distilling off the solvent to obtain powder mixed with acid monomer and amine monomer;

a1 mg/mL acetonitrile solution was prepared for LC/MS measurement.

LC：

The device comprises the following steps: waters corporation, UPLC

Column: waters corporation, ACQUITY UPLC HSS T31.8um

(2.1mm I.D.×100mm)

And (3) detection: PDA 200 and 800nm

Flow rate: 0.2 mL/min

Mobile phase: a is water (0.1% HCOOH)

B ═ acetonitrile (0.1% HCOOH)

Injection amount: 1 μ L

MS：

The device comprises the following steps: waters corporation, Synapt G2

Ionization: ESI +

The respective peak areas of the PDA chromatogram at 300nm obtained by the LC/MS measurement were obtained, and the ratio of the structural unit M to the total of the structural units L and M (M/(L + M)) was calculated from the peak area ratio according to the following calculation formula (1).

M/(L + M) ratio (%): [ (peak area of amine component of general formula (2)/{ (peak area of amine component of general formula (1)) + (peak area of amine component of general formula (2) } ]. times.100. ANG. (calculation formula 1)

< evaluation of laser ablation energy >

The resin compositions prepared in examples and comparative examples, respectively, were coated on a glass substrate (0.7 mm in thickness) in such a manner that the film thickness became 10 μm after curing, and were prebaked at 80 ℃ for 40 minutes. Thereafter, the oxygen concentration in the cell was adjusted to 10 ppm by mass or less using a vertical curing furnace (model name: VF-2000B, manufactured by Koyo Lindberg Co., Ltd.), and heat curing treatment was performed at 400 ℃ for 1 hour to prepare a laminate of a glass substrate and a polyimide resin film.

Irradiation is performed by excimer laser (wavelength of 308nm) while increasing irradiation energy stepwise from the glass substrate side of the laminate obtained as described above, and the minimum irradiation energy for peeling polyimide is set to 10mJ/m higher than the minimum irradiation energy²The obtained energy was evaluated for ash (ash content) when irradiated. When no ash was produced, the mark was ≈ when a small amount of ash was observed deep, and the mark was ×, when ash was observed over the entire surface.

In the case of laser peeling, the polyimide film may burn with laser light, and the combustion residue may be ash.

< evaluation of annealing of inorganic film/polyimide laminate >

In the same manner as the < evaluation of residual stress > described above, silicon wafers having a polyimide resin film having a thickness of 10 μm after curing were produced using the resin compositions of examples and comparative examples in the same manner as the < evaluation of residual stress > described above.

A SiOx film having a thickness of 50nm was formed on the polyimide resin film by Chemical Vapor Deposition (CVD). The laminate thus obtained was annealed at 450 ℃ for 30 minutes while adjusting the oxygen concentration in the cell to 10 mass ppm or less using a vertical curing furnace (model name: VF-2000B, manufactured by Koyo Lindberg).

After the annealing treatment, the SiOx film surface was observed with a laser microscope (type: VK-8700, manufactured by Kinzhi), and the presence or absence of cracks during the annealing treatment was observed in a 10mm square field of view. The evaluation was carried out according to the following criteria, and the results are shown in table 4.

A: no cracks were observed

B: the number of cracks is more than 1 and less than 9

C: the number of cracks is more than 10

Synthesis examples 1 and 2

Synthesis example 1(1-1)

Into a 500ml separable flask purged with nitrogen gas were charged 90.00g of N-methyl-2-pyrrolidone (NMP), 11.30g (49.5mmol) of 4-aminophenyl-4-aminobenzoate (APAB), and 1.06mg (5.0. mu. m.o.l) of 4, 4-azodiphenylamine (AzBz), and the APAB and the AzBz were dissolved with stirring. Then, 14.7g (50mmol) of biphenyl-3, 3 ', 4, 4' -tetracarboxylic dianhydride (BPDA) and 13.25g of N-methyl-2-pyrrolidone (NMP) were added to adjust the concentration of the polyamic acid to 20 mass%, and polymerization was carried out under a nitrogen gas flow at 80 ℃ for 3 hours with stirring. Thereafter, the reaction mixture was cooled to room temperature to obtain an NMP solution of polyamic acid (hereinafter also referred to as a varnish containing a polyimide precursor). The weight average molecular weight (Mw) of the obtained polyamic acid was about 100,000.

Synthesis examples 1(1-2 to 5-3) and 2(1 to 5)

Varnish containing a polyimide precursor was obtained in the same manner as in synthesis example 1(1-1) except that the amounts of raw materials charged in synthesis example 1(1-1) were changed as shown in table 1. The numbers shown in table 1 indicate molar parts. The weight average molecular weight (Mw) of the polyimide precursor contained in each varnish is shown in table 2.

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

BPAF: 9, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride

TAHQ: p-phenylene bis (trimellitic anhydride)

DSDA: 3,3 ', 4, 4' -diphenylsulfone tetracarboxylic dianhydride

ODPA: 4, 4' -oxydiphthalic anhydride

CpODA: cyclopentanone bis-spironorbornane tetracarboxylic dianhydride

APAB: 4-aminophenyl-4-aminobenzoic acid ester

2F-APAB: 2-fluoro-4-aminophenyl-4-aminobenzoic acid ester

3F-APAB: 3-fluoro-4-aminophenyl-4-aminobenzoic acid ester

3 Me-APAB: 3-methyl-4-aminophenyl-4-aminobenzoic acid ester

44 DAS: 4, 4' -diaminodiphenyl sulfone

BAFL: 9, 9-bis (aminophenyl) fluorenes

DABA: 4, 4' -diaminobenzanilides

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

BAFL: 9, 9-bis (aminophenyl) fluorenes

AzBz: 4, 4' -azodiphenylamine

Azo-APAB: bis (4, 1-phenylene) bis (4-aminobenzoate) diazene-1, 2-diyl (C-1)

Azo-2F-APAB: bis (2-fluoro-4, 1-phenylene) bis (4-aminobenzoate) diazene-1, 2-diyl (C-2)

Azo-3F-APAB: bis (3-fluoro-4, 1-phenylene) bis (4-aminobenzoate) diazene-1, 2-diyl (C-3)

Azo-3 Me-APAB: bis (3-methyl-4, 1-phenylene) bis (4-aminobenzoate) diazene-1, 2-diyl (C-4)

Films were produced and evaluated as described above using the varnishes obtained in the respective synthesis examples as they were as resin compositions (examples 1 to 24 and comparative examples 1 to 5). The evaluation results are shown in tables 2 and 3.

As is clear from tables 2 and 3: the polyimide film of comparative example 1 containing the structural unit represented by the general formula (2) at a ratio less than the range of one embodiment of the present invention with respect to the structural unit represented by the general formula (1) was not peeled off by laser light, and ash was generated. The polyimides of comparative examples 2 to 5, which contain the structural unit represented by the general formula (2) at a ratio exceeding one embodiment of the present invention with respect to the structural unit represented by the general formula (1), have a large yellowness (YI value) and Haze (Haze value).

On the other hand, the polyimide films of examples 1 to 24, which contained the structural unit represented by the general formula (2) at a ratio in the range of 0.005 to 0.5% relative to the structural unit represented by the general formula (1), had a yellowness (YI value) of 30 or less, a residual stress of 20MPa or less, and a Haze (Haze value) of less. Further, no or slight warpage occurred after the inorganic film was formed. The content is more preferably 0.35% or less from the viewpoint of Haze (Haze value) (examples 3 and 14), and more preferably 0.005% or more from the viewpoint of laser peelability (examples 1, 13 and 15). Furthermore, from the viewpoint of residual stress, it is more preferable to contain BPDA of 25 mol% or more (examples 4 to 8), from the viewpoint of warpage evaluation, it is preferable to contain APAB of 20 mol% or more (examples 10 and 11), and from the viewpoint of yellowness (YI value), it is more preferable to contain BPAF, TAHQ, ODPA, CpODA of 10 mol% or more (examples 4 to 8).

From the experimental results of table 2 above, it was confirmed that: the polyimide resin film obtained from the resin composition of the present invention has a low yellowness (YI value), a low residual stress, a low Haze (Haze value), and excellent laser peelability.

Next, a measurement method by high performance liquid chromatography-mass spectrometry (hereinafter, also referred to as LC/MS) will be described. As shown in the examples, the concentration of the resin composition prepared in the synthesis example was adjusted to 1.0 mass%, and then an appropriate amount of water was added, and heat treatment was performed at 80 ℃ for 3 days to depolymerize the acid component and the amine component, thereby preparing an acid monomer and an amine monomer, and the solvent was distilled off to obtain a powder in which the acid monomer and the amine monomer were mixed, thereby preparing a 1mg/mL acetonitrile solution to be subjected to LC/MS measurement. The content of each component was determined from the peak area of the elution time corresponding to each component in the PDA chromatogram at 300 nm.

For example, in the LC/MS measurement using the polyimide precursor described in example 3, among the experimental results shown in the PDA chromatogram at 300nm, the following were identified by MS (mass spectrometry) measurement: 4.07min (peak height: 15176803 count, peak area: 1473470.38 count) was derived from APAB, 5.42min (peak height: 76120 count, peak area: 2649.47 count), 6.97min (peak height: 38570 count, peak area: 1502.06 count) was derived from dimer of APAB having-NHNH-bond, 9.28min (peak height: 21195 count, peak area: 1058.44 count) was derived from dimer of APAB having-N ═ N-bond. The content was calculated from the calculation formula described in < evaluation method of content (ratio of structural unit M to total of structural unit L and structural unit M) > above using the peak areas of the structural unit (APAB) represented by general formula (1) and the structural unit represented by general formula (2). The content was 0.35%.

[ Table 1]

[ Table 2]

TABLE 2

[ Table 3]

TABLE 3

[ Table 4]

TABLE 4

Industrial applicability

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

Claims

1. A polyimide precursor comprising (a1) a structural unit L represented by the following general formula (1) and (a2) a structural unit M represented by the following general formula (2),

in the formula (1), X represents a 4-valent organic group, Y₁Represents a 2-valent organic group;

in the formula (2), X represents a 4-valent organic group, Y₂Represents a 2-valent organic group, Z represents-NHNH-or-N ═ N-,

y in the general formula (2)₂Is at least 1 kind selected from the group consisting of structures represented by the following general formulas (A-1) to (A-6),

in the formula, R₁～R₁₃Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, a to m are each independently an integer of 0 to 4, n is an integer of 1 or more, a represents a bonding site,

2. The method of claim 1Wherein said Y is₂Is at least 1 selected from the group consisting of the structures represented by the general formula (A-1) and the general formula (A-6).

3. A polyimide precursor comprising (a1) a structural unit L represented by the following general formula (1) and (a2) a structural unit M represented by the following general formula (2),

y in the general formula (2)₂Is a structure represented by the following general formula (A-6),

in the formula (A-6), R₁₃Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, m is an integer of 0 to 4, n is an integer of 1 or more, and x represents a bonding site.

4. The polyimide precursor according to any one of claims 1 to 3, wherein Y in the general formula (1)₁Is at least 1 kind selected from the group consisting of structures represented by the following general formulas (A-1) to (A-5),

in the formula, R₁～R₁₂Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, a to l each independently represents an integer of 0 to 4, and represents a bonding site.

5. The polyimide precursor according to any one of claims 1 to 4, wherein X in the general formula (1) or the general formula (2) or both is a 4-valent group derived from at least 1 selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyl tetracarboxylic dianhydride (BPDA), 4,4 '-biphenyl bis (trimellitic acid monoester anhydride) (TAHQ), 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF), 3', 4,4 '-diphenylsulfone tetracarboxylic dianhydride (DSDA), 4, 4' -oxydiphthalic anhydride (ODPA) and cyclopentanone bisspironorbornane tetracarboxylic dianhydride (CpODA).

6. A resin composition comprising (a) the polyimide precursor according to any one of claims 1 to 5 and (b) an organic solvent.

7. The resin composition according to claim 6, further comprising at least 1 selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.

8. The resin composition according to claim 6 or 7, wherein a polyimide resin film obtained by curing the resin composition is used for a flexible device.

9. The resin composition according to claim 6 or 7, wherein a polyimide resin film obtained by curing the resin composition is used for a flexible display.

10. A polyimide film obtained from the polyimide precursor according to any one of claims 1 to 5 or the resin composition according to any one of claims 6 to 9.

11. A polyimide comprising a structural unit represented by the following general formula (3),

in the formula (3), X independently represents a 4-valent organic group, Y₁And Y₂Each independently represents a 2-valent organic group, l and m are each independently an integer of 1 or more, wherein 0.005. ltoreq. m/(l + m). ltoreq.0.5 is satisfied;

said Y is₂Is at least 1 selected from the group consisting of structures represented by the following general formulae (A-1) and (A-6),

in the formula, R₁、R₂And R₁₃Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, a, b and m are each independently an integer of 0 to 4, n is an integer of 1 or more, and x represents a bonding site.

12. A polyimide comprising a structural unit represented by the following general formula (3),

in the formula (3), X independently represents a 4-valent organic group, Y₁Each independently represents a 2-valent organic group, Y₂Is a structure represented by the following general formula (A-6), l and m are each independently an integer of 1 or more, wherein 0.005. ltoreq. m/(l + m) 0.5 is satisfied,

in the formula (A-6), R₁₃Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or a halogen, m is each independently an integer of 0 to 4, n is an integer of 1 or more, and x represents a bonding site.

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

a step of forming a coating film by applying the resin composition according to any one of claims 6 to 9 on the surface of a support;

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

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

14. The method for manufacturing a resin thin film according to claim 13, further comprising: a step of irradiating the polyimide resin film with a laser beam from the support body side before the step of peeling the polyimide resin film from the support body.

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

a step of forming a coating film by applying the resin composition according to any one of claims 6 to 9 on the surface of a support; and

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

16. A method for manufacturing a display substrate includes the steps of:

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