CN113549217B

CN113549217B - Polyimide precursor, resin composition containing same, polyimide resin film, and method for producing same

Info

Publication number: CN113549217B
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: 2024-03-08
Anticipated expiration: 2041-04-23
Also published as: CN113549217A

Abstract

A polyimide precursor, 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, little warpage, low yellowness (YI value) at high temperatures (especially 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 (a 1) a structural unit L represented by the general formula (1) and (a 2) a structural unit M represented by the general formula (2), wherein the amount of the structural unit M is 0.005 to 0.5 mol% based on the total amount of the structural unit L and the structural unit M.

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 manufacture of a substrate for flexible devices, and a resin composition, a polyimide resin film, a resin film, and a method for manufacturing the same, including the same.

Background

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

Polyimide resins are insoluble and infusible super heat resistant resins, and have excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low temperature resistance, and chemical resistance. Accordingly, 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 protection films for thin film transistor liquid crystal displays (TFT-LCDs). Recently, applications of glass substrates, which are used in the field of display materials in place of glass substrates used in the past, have been studied as flexible substrates utilizing their light weight and flexibility.

When 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 a suitable support such as a glass substrate, and the resultant is dried to form a thin film, which is then formed into an element, a circuit, or the like, and then the thin film is peeled off from the glass substrate. However, in the case of producing a laminate having a polyimide resin, there is a heat treatment at a high temperature of 250 ℃ or higher for the purpose of drying and imidization of a polyimide precursor. The heat treatment causes residual stress in the laminate, and serious problems such as warpage and peeling occur. This is because: polyimide has a linear expansion coefficient larger than that of the material constituting the support.

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

Further, polyimide having an ester structure in a molecular chain is reported to exhibit a low linear expansion coefficient due to moderate linearity and rigidity (patent document 1).

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

Prior art literature

Patent literature

Patent document 1: international publication No. 2005/113647

Patent document 2: international publication No. 2019/211972

Non-patent literature

Non-patent document 1: "latest polyimide-base and application- (latest sheath-base mW-)", edited by the Japanese polyimide research institute

Disclosure of Invention

Problems to be solved by the invention

However, in order to use a polyimide resin as a colorless transparent flexible substrate, not only transparency, excellent mechanical properties such as elongation and breaking strength, but also laser peelability from the substrate is required. In particular, recently, as the device type of TFT is changed to LTPS (low temperature polysilicon TFT), a thin film exhibiting the above physical properties even in a thermal history exceeding the conventional one is desired. However, the properties of the known transparent polyimide are not sufficient for use as a heat-resistant colorless transparent substrate for a display. 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), a high residual stress, a low elongation, and a low breaking strength.

Regarding the laser peelability, although the polyimide film described in patent document 2 shows excellent performance, the inventors of the present invention 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 the yellowness (YI value) is significantly deteriorated in a high temperature range of 430 ℃ or higher, and the Haze (Haze value) is increased, and visibility is lowered.

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

Solution for solving the problem

The present invention includes the following aspects.

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

{ in formula (1), X represents a 4-valent organic group, Y ₁ Represents a 2-valent organic group. }

{ in formula (2), X represents a 4-valent organic group, Y ₂ Represents a 2-valent organic group, Z represents-NHNH-or-N=N-. }

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

{ in which R ₁ ～R ₁₃ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, a to m are each independently integers of 0 to 4,n is an integer of 1 or more, and represents a bonding site. }

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%.

[2]The polyimide precursor according to the above aspect 1, wherein the above Y ₂ 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 (a 1) a structural unit L represented by the following general formula (1) and (a 2) a structural unit M represented by the following general formula (2),

Y in the above general formula (2) ₂ The structure is represented by the following general formula (A-6).

{ in formula (A-6), R ₁₃ Each independently 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 represents a bonding site. }

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

{ in which R ₁ ～R ₁₂ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, and a to l each independently represents an integer of 0 to 4. }

[5] The polyimide precursor according to any one of the above modes 1 to 4, wherein X in the above general formula (1) or the above 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 '-biphenylbis (trimellitic monoester anhydride) (TAHQ), 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF), 3',4 '-diphenyl sulfone tetracarboxylic dianhydride (DSDA), 4' -oxydiphthalic anhydride (ODPA) and cyclopentanone dispiro-bornane tetracarboxylic dianhydride (CpODA).

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

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

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

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

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

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

{ in formula (3), X independently represents a 4-valent organic group, Y ₁ And Y ₂ Each independently represents a 2-valent organic group, and l and m are each independently integers of 1 or more, wherein 0.005.ltoreq.m/(l+m). Ltoreq.0.5 is satisfied. }

The aforementioned Y ₂ At least 1 selected from the group consisting of structures represented by the following general formulae (A-1) and (A-6).

{ in which R ₁ 、R ₂ And R is ₁₃ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, a, b, and m are each independently integers of 0 to 4, n is an integer of 1 or more, and represents a bonding site. }

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

{ in formula (3), X independently represents a 4-valent organic group, Y ₁ Each independently represents a 2-valent organic group, Y ₂ In the structure shown by the following general formula (A-6), l and m are each independently integers of 1 or more, wherein 0.005.ltoreq.m/(l+m). Ltoreq.0.5 is satisfied. }

(in the formula (A-6), R ₁₃ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or 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 producing 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 a surface of a support;

a step of forming a polyimide resin film by heating the support and the coating film to imidize a polyimide precursor contained in the coating film; and

and peeling the polyimide resin film from the support.

[14] The method for producing a resin film according to the above-described mode 13, further comprising: and irradiating laser light from the support side before the step of peeling the polyimide resin film from the support.

[15] A method for producing 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 a 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:

a step of forming a polyimide resin film by heating the support and the coating film to imidize a polyimide precursor contained in the coating 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 circuit is formed 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 little warpage, has a small yellowness (YI value) at high temperature (particularly, 430 ℃ or higher), has a small Haze (Haze value), and is excellent in laser peelability from a substrate.

Drawings

Fig. 1 is a schematic view showing a structure of a top emission type flexible organic EL display, which is an example of the display of the present embodiment, above a polyimide substrate.

Description of the reference numerals

2a lower substrate

2b sealing substrate

25. Organic EL structure part

250a emitting red light

250b emitting green light

250c blue light-emitting organic EL element

251. Partition wall (dyke)

252. Lower electrode (anode)

253. Hole transport layer

254. Light-emitting layer

255. Upper electrode (cathode)

256 TFT

257. Contact hole

258. Interlayer insulating film

259. Lower electrode

261. Hollow part

Detailed Description

Hereinafter, an exemplary embodiment of the present invention (hereinafter, abbreviated as "this embodiment") will be described in detail. The present invention is not limited to the following embodiments, and may be implemented by various modifications within the scope of the present invention. The characteristic values described in the present application are measured by the method described in the item [ example ] or the method considered equivalent thereto by those skilled in the art unless otherwise specified.

< polyimide precursor >

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

In the formula { wherein X represents a 4-valent organic group, Y ₁ Represents a 2-valent organic group. }

In the formula { wherein X represents a 4-valent organic group, Y ₂ Represents a 2-valent organic group, 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 with respect to the total amount of the structural unit L and the structural unit M is calculated by the method shown below. Specifically, after separating the polyimide precursor into an acid component and an amine component by depolymerization, the polyimide precursor is separated into the amine component of the above general formula (1) and the amine component of the above general formula (2) by high performance liquid chromatography-mass spectrometry (hereinafter also referred to as LC/MS), and the peak area ratio [ (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 is calculated as a ratio (%).

If the above ratio is 0.005 mol% or more, the laser peelability tends to be good, and if it is 0.5 mol% or less, the yellowness of the polyimide film tends to be good, and ashes after laser peeling can be suppressed. In the case of laser peeling, the polyimide film may burn by laser light, and the combustion residue may be ash. From the viewpoint of suppressing yellowness, the above ratio is preferably 0.35 mol% or less, 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, and low yellowness (YI value) when used in the production of a polyimide film, and is excellent in laser peelability from a substrate. In addition, when the polyimide precursor of the first embodiment is produced into a polyimide film, the yellowness (YI value) and Haze (Haze value) in a high temperature region are small.

(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 present in the polyimide precursor are optionally the same or different from each other. Examples of X include 4-valent organic groups derived from the following tetracarboxylic dianhydrides.

Examples of the tetracarboxylic dianhydride include aromatic tetracarboxylic dianhydrides having 8 to 36 carbon atoms, aliphatic tetracarboxylic dianhydrides having 6 to 36 carbon atoms, and alicyclic tetracarboxylic dianhydrides having 6 to 36 carbon atoms. Among them, aromatic tetracarboxylic dianhydrides having 8 to 36 carbon atoms are 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 6 FDA), 5- (2, 5-dioxotetrahydro-3-furyl) -3-methyl-cyclohexene-1, 2-dicarboxylic anhydride, pyromellitic dianhydride (hereinafter also referred to as PMDA), 1,2,3, 4-pyromellitic dianhydride, 3',4,4 '-benzophenone tetracarboxylic dianhydride, 2',3 '-benzophenone tetracarboxylic dianhydride, 3',4,4 '-biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA), 3',4 '-diphenylsulfone tetracarboxylic dianhydride (hereinafter also referred to as DSDA), 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-phenylene bis (trimellitic anhydride) (hereinafter also referred to as TAHQ), thio-4, 4 '-diphthalic dianhydride, sulfonyl-4, 4' -diphthalic dianhydride, the reaction of 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, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, bis (3, 4-dicarboxyphenoxy) dimethylsilane dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) -1, 3-tetramethyldisiloxane dianhydride, 2,3,6, 7-naphthalene tetracarboxylic dianhydride, 1,4,5, 8-naphthalene tetracarboxylic dianhydride, 1,2,5, 6-naphthalene tetracarboxylic dianhydride, 3,4,9, 10-perylene tetracarboxylic dianhydride, 2,3,6, 7-anthracene tetracarboxylic dianhydride, 1,2,7, 8-phenanthrene tetracarboxylic 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-cyclobutane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane-1, 2,3, 4-tetracarboxylic dianhydride, cyclohexane-1, 2,4, 5-tetracarboxylic dianhydride, cyclopentanone bisspiro-norbornane 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-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] 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' -diketone), 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 Coefficient of Thermal Expansion (CTE), chemical resistance, glass transition temperature (Tg), and yellowness in a high temperature region, PMDA, BPDA, DSDA, TAHQ, ODPA, cpODA is 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 described above within a 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 preferred are 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. Of these, dicarboxylic acids having an aromatic ring are preferable.

In particular, the method comprises the steps of, 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' -sulfonyldibenzoic acid, and 3,4' -sulfonyldibenzoic acid, 3' -sulfonyldibenzoic acid, 4' -oxybenzoic acid, 3' -oxybenzoic acid, 2-bis (4-carboxyphenyl) propane, 2-bis (3-carboxyphenyl) propane, 2' -dimethyl-4, 4' -biphenyldicarboxylic acid, and 3,4' -sulfonyldibenzoic acid, 3' -sulfonyldibenzoic acid, 4' -oxybisbenzoic acid, 3' -oxybisbenzoic acid 2, 2-bis (4-carboxyphenyl) propane, 2-bis (3-carboxyphenyl) propane, 2' -dimethyl-4, 4' -biphenyldicarboxylic acid, 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-cyclobutanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1, 2-cyclohexanedicarboxylic acid, 4' -benzophenone dicarboxylic acid, 1, 3-phenylene diacetic acid, 1, 4-phenylene diacetic acid, and the like; and

And 5-aminoisophthalic acid derivatives described in WO 2005/068535. When these dicarboxylic acids are actually copolymerized with the polymer, the polymer may be used in the form of an acid chloride derived from thionyl chloride or the like, an active ester or the like.

In the general formula (1), Y ₁ The 2-valent organic group may preferably be at least 1 of structures represented by the following general formulae (A-1) to (A-5). As Y ₁ The structure represented by the general formula (A-1) is preferable from the viewpoints of yellowness (YI value) in a high temperature region and laser releasability.

General formula (A-1):

{ in which R ₁ And R is ₂ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, and a and b each independently represent an integer of 0 to 4. }

Here, R is ₁ And R is ₂ The organic group having 1 to 20 carbon atoms and the halogen are not limited as long as they are each independently a 1-valent organic group or a halogen. Examples of the organic group include alkyl groups such as methyl, ethyl, and propyl; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Examples of the halogen include a fluoro group and the like. Wherein from the yellow degree (YI value) and fog in the high temperature regionFrom the viewpoint of the degree (Haze value), methyl and fluoro groups are preferable.

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 yellowness (YI value) and residual stress, and 0 is particularly preferable from the viewpoint of yellowness (YI value) in a high temperature region.

General formula (A-2):

{ in which R ₃ And R is ₄ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, and d and e are each independently integers of 0 to 4, which are bonding sites. }

Here, R is ₃ And R is ₄ The organic group having 1 to 20 carbon atoms and the halogen are not limited as long as they are each independently a 1-valent organic group or a halogen. Examples of such an organic group 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 yellowness (YI value) in a 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 yellowness (YI value) and residual stress, and 0 is particularly preferable from the viewpoint of yellowness (YI value) in a high temperature region.

General formula (A-3):

{ in which R ₅ ～R ₈ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, and e to h are each independently integers of 0 to 4, and are bonding sites. }

Here, R is ₅ ～R ₈ The organic group having 1 to 20 carbon atoms and the halogen are not limited as long as they are each independently a 1-valent organic group or a halogen. As thisExamples of the organic group include alkyl groups such as methyl, ethyl, and propyl; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Among them, methyl is preferable from the viewpoint of yellowness (YI value) in a high temperature region.

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

General formula (A-4):

{ in which R ₉ And R is ₁₀ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, and i and j are each independently integers of 0 to 4, which are bonding sites. }

Here, R is ₉ And R is ₁₀ The organic group having 1 to 20 carbon atoms and the halogen are not limited as long as they are each independently a 1-valent organic group or a halogen. Examples of such an organic group 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 yellowness (YI value) in a high temperature region.

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 yellowness (YI value) and residual stress, and 0 or 1 is particularly preferable from the viewpoint of yellowness (YI value) in a high temperature region.

General formula (A-5):

{ in which R ₁₁ And R is ₁₂ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, and k and l are integers of 0 to 4 and are bonding sites. }

Here, R is ₁₁ And R is ₁₂ The organic group having 1 to 20 carbon atoms and the halogen are not limited as long as they are each independently a 1-valent organic group or a halogen. Examples of the organic group include alkyl groups such as methyl, ethyl, and propyl; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Examples of the halogen include a fluoro group and the like. Among them, methyl and fluoro groups are preferable from the viewpoint of yellowness (YI value) in a high temperature region.

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

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

{ in which R ₁ 、R ₂ A, a and b are as defined for the general formula (A-1). }

The diamine represented by the general formula (B-1) may be exemplified by 4-aminophenyl-4-aminobenzoate (hereinafter also referred to as APAB), 2-methyl-4-aminophenyl-4-aminobenzoate (hereinafter also referred to as 2 Me-APAB), 3-methyl-4-aminophenyl-4-aminobenzoate (hereinafter also referred to as 3 Me-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 3,3 Me-APAB), and the like, from the viewpoint of reducing Haze (Haze value), APAB, 3Me-APAB, 3F-APAB, and 3,3Me-APAB are preferable.

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

{ in which R ₃ 、R ₄ C and d are as defined for formula (A-2). }

As the diamine represented by the general formula (B-2), more specifically, 4 '-diaminodiphenyl sulfone (hereinafter also referred to as 44 DAS), 3' -diaminodiphenyl sulfone and the like can be exemplified.

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

{ in which R ₅ ～R ₈ And e to h are defined as in 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, 9-bis [4- (4-aminophenoxy) phenyl ] fluorene, and the like, and preferably 1 or more selected from these are used.

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

{ in which R ₉ 、R ₁₀ I and j are defined as in formula (A-4). }

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

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

{ in which R ₁₁ 、R ₁₂ K and l are as defined for formula (B-5). }

As the diamine represented by the general formula (B-5), more specifically, 4' -diaminobenzanilide (hereinafter also referred to as DABA) and the like can be exemplified.

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

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

In the above general formula (2), Y ₂ It 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 with respect to the general formula (1) and the structure represented by the following general formula (A-6).

{ in which R ₁₃ Independently 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, R is ₁₃ The organic group having 1 to 20 carbon atoms and the halogen are not limited as long as they are each independently a 1-valent organic group or a halogen. Examples of the organic group include alkyl groups such as methyl, ethyl, and propyl; halogen-containing groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy. Examples of the halogen include a fluoro group and the like. Among them, methyl and fluoro groups are preferable from the viewpoint of yellowness (YI value) in a 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 Y ₂ From a high temperature regionFrom the viewpoints of yellowness (YI value) and laser peelability in the domain, 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 above general formula (2), Z is a bond represented by-NHNH-or-N=N-and the polyimide precursor may contain only one or both of them. Among them, from the viewpoint of yellowness (YI value) in a high temperature region, a-n=n-bond is preferable. In general, azo compounds having a bond of-n=n-are known to undergo photoisomerization by light, and it can be considered that: the azo structure is excited by the laser energy irradiated at the time of laser lift-off, and laser lift-off property is improved. Therefore, absorbance around the wavelength (e.g., 308 nm) of laser lift-off, which is commonly used, is important. The structure represented by the general formula (2) preferably has good absorbance at the wavelength of the laser lift-off 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 having a 300nm detector. Since the-NHNH-bond is reduced to the-n=n-bond at the time of thermal imidization, the improvement of laser peelability can be facilitated similarly to the-n=n-bond.

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

{ in which R ₁₃ M and n are as defined for formula (A-6). }

As the diamine represented by the general formula (B-6), more specifically, 4' -azobis aniline (hereinafter also referred to as AzBz) and the like can be exemplified.

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-3 Me-APAB)

The polyimide precursor of the present embodiment preferably has a weight average molecular weight (Mw) of 10,000 ～ 300,000, and particularly preferably 30,000 ～ 200,000. When the weight average molecular weight is 10,000 or more, mechanical properties such as elongation and breaking strength are excellent, and the residual stress becomes low, and YI becomes low. When the weight average molecular weight is 300,000 or less, the weight average molecular weight can be easily controlled at the time of synthesis of the polyamic acid, and a resin composition having a proper 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 using gel permeation chromatography (hereinafter also referred to as GPC).

The content of the molecules having a molecular weight of less than 1,000 in the polyimide precursor of the present embodiment is preferably less than 5 mass%, more preferably less than 1 mass% with respect to the total amount of the polyimide precursor. The polyimide film formed from the resin composition obtained by using such a polyimide precursor has a low residual stress, and the Haze (Haze value) of the inorganic film formed on the polyimide film is low. The content of the molecule 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, Y ₁ And Y ₂ Each independently represents a 2-valent organic group, and l and m are each independently integers of 1 or more, wherein 0.005.ltoreq.m/(l+m). Ltoreq.0.5 is satisfied. }

X, Y in the general formula (3) ₁ And Y ₂ Examples of (2) may be as described above for X, Y in general formulae (1) and (2) ₁ And Y ₂ The same is true for the examples of (a).

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 balance of CTE, chemical resistance, tg and yellowness (YI value) in a high temperature region.

Y in the general formula (3) ₁ Can be combined with Y in the general formula (1) ₁ The same groups are exemplified, 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 the structures represented by the general formulae (B-1) to (B-5). In addition, Y ₂ And Z may be the same as Y in the general formula (2) ₂ The same groups as exemplified for Z, e.g. Y ₂ Can be a 2-valent organic group represented by the general formulae (A-1) to (A-6), -Y ₂ -Z-Y ₂ The structure may be derived from a diamine of the general formula (B-6).

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

The polyimide precursor according to the first embodiment and the polyimide according to the second embodiment may be any diamine other than the diamines represented by the general formulae (B-1) to (B-6) and (C-1) to (C-4) described above, so long as they do not impair elongation, strength, stress, laser releasability, yellowness, and the like.

As a further diamine, a diamine may be used, examples thereof include p-phenylenediamine, m-phenylenediamine, 4' -diaminodiphenyl sulfide, 3' -diaminodiphenyl sulfide, 4' -diaminobiphenyl, 3' -diaminobiphenyl, 4' -diaminobenzophenone, and 3,4' -diaminobenzophenone, 3' -diaminobenzophenone, 4' -diaminodiphenylmethane, 3' -diaminodiphenylmethane, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene 1, 3-bis (3-aminophenoxy) benzene, 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, 2-bis [ 4- (4-aminophenoxy) phenyl) hexafluoropropane, 1, 4-bis (3-aminopropyl dimethylsilyl) benzene and the like are preferably used, and 1 or more selected from these are used. The content of the other diamine in the whole diamines is preferably 20 mol% or less, particularly preferably 10 mol% or less.

[ production of polyimide precursor ]

The polyimide precursor (specifically, polyamic acid) of the present embodiment can be synthesized by polycondensation of 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). The reaction is preferably carried out in a suitable solvent. Specifically, for example, a method in which predetermined amounts of APAB and AzBz are dissolved in a solvent, and then a predetermined amount of tetracarboxylic dianhydride is added to the resulting diamine solution and stirred is given.

The diamine component is not limited as long as 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 0.005 to 0.5 mol% in terms of (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 the ash after laser peeling tends to be suppressed. If the diamine used in the structural unit represented by the general formula (1) is 99.5 mol% or more, the residual stress of the obtained 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 the synthesis of the polyimide precursor of the present embodiment is preferably set to a range of tetracarboxylic dianhydride:diamine=100:90 to 100:110 (0.90 to 1.10 parts by mole of diamine relative to 1 part by mole of tetracarboxylic dianhydride), more preferably to a 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, in the synthesis of a polyamic acid that is a preferable polyimide precursor, 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 blocking agent used, the more the molecular weight of the polyamic acid can be increased.

As the tetracarboxylic dianhydride component and the diamine component, high purity products are recommended. The purity is preferably 98 mass% or more, more preferably 99 mass% or more, and still more preferably 99.5 mass% or more, respectively. When a plurality of acid dianhydride components or diamine components are used in combination, it is sufficient that the above-mentioned purity is provided in terms of the whole of the acid dianhydride components or diamine components, but it is preferable that all kinds of acid dianhydride components and diamine components used have the above-mentioned purity, respectively. As other components, a diamine for forming the structural unit M represented by the general formula (2) may be contained. On the other hand, it is preferable that the diamine for forming the structural unit M represented by the general formula (2) is not contained with impurities other than diamine.

The reaction solvent is not particularly limited as long as it is a solvent capable of dissolving the tetracarboxylic dianhydride component and the diamine component, and the polyamic acid produced, and obtaining a high molecular weight polymer. Specific examples of such solvents include aprotic solvents, phenolic solvents, ethers, and glycol solvents. Specific examples thereof include: amide solvents such as N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N-methylcaprolactam, 1, 3-dimethylimidazolidone, tetramethylurea, EQUATIE M100 (trade name: manufactured by Ming of light emission Co., ltd.) and EQUATIMIE B100 (trade name: manufactured by Ming of light emission Co., ltd.) as the aprotic solvent;

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

a phosphorus-containing amide solvent such as hexamethylphosphoramide and hexamethylphosphoric triamide;

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

ketone solvents such as cyclohexanone and methylcyclohexanone;

tertiary amine solvents such as picoline and pyridine;

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

examples of the phenol-based solvents 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 used for synthesizing the polyamic acid is preferably 60 to 300 ℃, more preferably 140 to 280 ℃, particularly preferably 170 to 270 ℃ at normal pressure. 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 ℃, roughness of the surface of the resin film, mixing of bubbles into the resin film, and the like may occur in the drying step, and a uniform film may not be obtained.

In this way, from the viewpoints of solubility and edge exclusion at the time of coating, a solvent having a boiling point of 170 to 270 ℃ is preferable, and a solvent having a vapor pressure of 250Pa or less at 20 ℃ is more preferable. 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 singly or in combination of 2 or more.

As described above, the content of the molecules having a molecular weight of less than 1,000 in the polyimide precursor of the present embodiment is preferably less than 5 mass%. The reason why the molecules having a molecular weight of less than 1,000 exist in the polyimide precursor is considered to be related to the moisture content of the solvent used in the synthesis. I.e. can be considered as: part of the acid dianhydride monomer anhydride gene is hydrolyzed by moisture to form carboxyl, and the carboxyl remains in a low molecular state without high 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, more preferably 1,000 mass ppm or less.

It can be considered that: the amount of moisture in the solvent is related to the grade of the solvent used (dehydration grade, general grade, etc.), the solvent container (bottle, 18L tank, small tank, etc.), the state of storage of the solvent (whether rare gas is enclosed or not), the time from unsealing to use (whether to use immediately after unsealing or whether to use again after a certain time has elapsed after unsealing, etc.), and the like. Furthermore, it can be considered that: it also relates to the substitution of rare gas in the reactor before synthesis, whether or not rare gas is circulated during synthesis, and the like. Therefore, in the synthesis of polyimide precursors, it is recommended to use a high-purity product as a raw material, use a solvent having a small amount of moisture, and take measures such that moisture from the environment is not mixed into the system before and during the reaction.

When each monomer component is dissolved in the solvent, heating may be performed as needed.

The reaction temperature in synthesizing the polyimide precursor is preferably set to 0 to 120 ℃, more preferably 40 to 100 ℃, still more preferably 60 to 100 ℃. By performing the polymerization reaction at this temperature, a polyimide precursor having a high polymerization degree 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 longer, a polyimide precursor having a high polymerization degree is formed, and when it is 100 hours or shorter, 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.

After a solution obtained by dissolving a polyimide precursor in a solvent (for example, N-methyl-2-pyrrolidone) is applied to the surface of a support, the solution is heated at 300 to 550 ℃ (for example, 430 ℃) under a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2,000 mass ppm or less), whereby the resin obtained by imidizing the polyimide precursor has a yellowness (YI value) of 30 or less at a film thickness of 10 μm.

After a solution obtained by dissolving a polyimide precursor in a solvent (for example, N-methyl-2-pyrrolidone) is applied to the surface of a support, the solution is heated at 300 to 550 ℃ (for example, 430 ℃) under 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 obtained by imidizing the polyimide precursor is 25MPa or less.

In a preferred embodiment of the present invention, a part of the polyimide precursor may be imidized (i.e., partially imidized). In this case, the imidization ratio is preferably 80% or less, more preferably 50% or less. Partial imidization can be generated by heating and dehydrating the polyimide precursor described above to close the ring. The heating for the partial imidization may be performed at a temperature of preferably 120 to 200 ℃, more preferably 150 to 180 ℃ for preferably 15 minutes to 20 hours, and more preferably 30 minutes to 10 hours.

Further, by adding N, N-dimethylformamide dimethyl acetal or N, N-dimethylformamide diethyl acetal to the polyamic acid obtained by the above reaction and heating, a part or all of carboxylic acid is esterified and used as the polyimide precursor of the present embodiment, a resin composition having improved viscosity stability at room temperature storage can be obtained. These ester-modified polyamic acids can be obtained by a method in which the acid dianhydride component is reacted with a dehydration-type thickener such as thionyl chloride and dicyclohexylcarbodiimide in an amount of 1 equivalent to the acid anhydride group, followed by a condensation reaction with a diamine component.

< resin composition >

In another embodiment of the present invention, a resin composition containing (a) a polyimide precursor and (b) an organic solvent is provided. 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 (a) polyimide precursor (preferably polyamic acid) 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) an organic solvent, a solvent as described above can be used as a solvent that can be used in the synthesis of (a) a polyimide precursor. The 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%. The composition and amount of the organic solvent (b) are preferably adjusted so that the viscosity (25 ℃) of the resin composition becomes 500 mPas to 100,000 mPas, and then the resin composition is added.

[ 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 above-described components (a) and (b).

The resin composition of the present embodiment contains (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 described above in the first embodiment and the second embodiment can be exemplified. In one embodiment, the skeleton of the polyimide precursor may be a skeleton having a structural unit represented by the aforementioned 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, streaks can be prevented from occurring in the coating film.

Examples of such surfactants include silicone surfactants, fluorine surfactants, and nonionic surfactants other than these surfactants. Examples of these include: examples of the silicone-based surfactant include organosiloxane polymers KF-640, 642, 643, KP341, X-70-092, X-70-093 (trade name, manufactured by Xinyue chemical Co., ltd.), SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (trade name, manufactured by Dow Corning Toray Silicone Co.), SILWET L-77, L-7001, FZ-2105, FZ-210, FZ-2154, FZ-2164, FZ-2166, L-7604 (trade name, manufactured by Japanese You Ni Co., ltd.), DBE-814, DBE-224, DBE-621, CMS-66, CMS-222, KF-352A, KF-L, KF-355A, KF-600, DBE-821, DBE-712 (Gelest), BYK-307, K-30, K-378, BYK-333 (trade name, manufactured by BYK-Chemie Co., ltd.), BYpan (trade name, manufactured by BYpan Co., ltd.), and the like;

Examples of the fluorine-based surfactant include Megafac F171, F173, R-08 (trade name, manufactured by japan ink chemical industry corporation), fluoroad FC4430, FC4432 (trade name, sumitomo 3M corporation), and the like;

examples of the nonionic surfactant other than the above are polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether, and the like.

Among these surfactants, silicone surfactants and fluorine surfactants are preferable from the viewpoint of the coatability (streak suppression) of the resin composition, and silicone surfactants are preferable from the viewpoint of the influence of the oxygen concentration at the curing step on the yellowness (YI value) and the total light transmittance. When the surfactant (c) is used, the compounding amount thereof is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, relative to 100 parts by mass of the polyimide precursor (a) in the resin composition.

[ (d) alkoxysilane Compound ]

In order to provide a resin film obtained from the resin composition of the present embodiment with sufficient adhesion between supports in a process for producing flexible devices or the like, the resin composition may contain 0.01 to 20 parts by mass of an alkoxysilane compound per 100 parts by mass of (a) a polyimide precursor. By setting the content of the alkoxysilane compound to 0.01 part by mass or more relative to 100 parts by mass of the polyimide precursor, good adhesion with the support can be obtained. From the viewpoint of storage stability of the resin composition, the content of the alkoxysilane compound is preferably 20 parts by mass or less. 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, relative to 100 parts by mass of the polyimide precursor.

By using an alkoxysilane compound as an additive of the resin composition of the present embodiment, in addition to the improvement of the adhesion, the coatability of the resin composition (suppression of streak unevenness) can be further improved, and the oxygen concentration dependence of the yellowness (YI value) of the obtained cured film upon curing can be reduced.

Examples of alkoxysilane compounds include 3-ureidopropyltriethoxysilane, bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, γ -aminopropyltrimethoxysilane, γ -aminopropyl-tributoxysilane, γ -aminoethyltrimethoxysilane, γ -aminobutyltrimethoxysilane, γ -aminobutyltrimutoxysilane, phenylsilanetriol, trimethoxyphenylsilane, trimethoxy (p-tolyl) silane, diphenylsilanediol, dimethoxydiphenylsilane, diethoxydiphenylsilane, dimethoxybis (p-tolyl) silane, and triphenylsilanol, and 1 or more selected from these compounds are preferably used.

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

In the case where the solvent used in synthesizing the (a) polyimide precursor is the same as the (b) organic solvent, the synthesized polyimide precursor solution may be directly used as the resin composition. If necessary, 1 or more of (b) an organic solvent and other components may be added to the polyimide precursor at a temperature ranging from room temperature (25 ℃) to 80℃and mixed with stirring to prepare a resin composition. For this stirring and mixing, a suitable device such as a Three one motor (manufactured by Xindong chemical Co., ltd.) having stirring blades and a rotation and revolution stirrer may be used. In addition, heat at 40℃to 100℃may be applied as required.

On the other hand, when the solvent used in synthesizing the (a) polyimide precursor is different from the (b) organic solvent, the solvent in the synthesized polyimide precursor solution is removed by an appropriate method such as reprecipitation or solvent distillation, and after the (a) polyimide precursor is separated, the (b) organic solvent and other components as needed are added in a temperature range of room temperature to 80 ℃, and the mixture is stirred and mixed, whereby the resin composition can also be prepared.

After the resin composition is prepared as described above, a part of the polyimide precursor may be dehydrated and imidized by heating the composition solution at, for example, 130 to 200℃for, for example, 5 minutes to 2 hours, to such an extent that the polymer is not precipitated. Here, the imidization rate can be controlled by controlling the heating temperature and the heating time. By partially imidizing the polyimide precursor, the viscosity stability of the resin composition can be improved when the resin composition is stored at room temperature. The range of the imidization ratio is preferably 5% to 70% from the viewpoint of showing a balance between 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 when the resin composition is stored, 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 ease of production of the resin composition.

The solution viscosity of the resin composition of the present embodiment is 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 was measured using an E-type viscometer (VISCONICEHD, manufactured by DONGMENTS INDUSTRIAL Co.). If the solution viscosity is less than 300mpa·s, coating is difficult when forming a film, and if it is more than 200,000mpa·s, stirring during synthesis may be difficult.

When the polyimide precursor (a) is synthesized, even if the solution has a high viscosity, a resin composition having a viscosity excellent in handleability can be obtained by adding a solvent and stirring the mixture after the reaction.

The resin composition of the present embodiment has the following characteristics in preferred embodiments.

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 ℃ under a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2,000 mass ppm or less), whereby a resin film obtained by imidizing a polyimide precursor contained in the coating film has a yellowness (YI value) of 30 or less at a film thickness of 10 μm.

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 ℃ under 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 is 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 flexible devices or flexible displays. Specifically, the present invention can be used for a substrate for forming a Thin Film Transistor (TFT), a substrate for a color filter, a substrate for a transparent conductive film (ITO, indium Tin Oxide), or the like.

The 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 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 aspect of the present invention provides a method for producing a resin film from the aforementioned resin composition.

The resin film according to 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, thereby forming a polyimide resin film; and a step of peeling the polyimide resin film from the support (peeling step).

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

a silicon wafer;

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

stainless steel, aluminum oxide, copper, nickel, etc.

In forming a polyimide molded article in a film shape, for example, a glass substrate, a silicon wafer, or the like is preferable, and in forming a polyimide molded article in a film shape or a sheet shape, a support made of, for example, PET (polyethylene terephthalate), OPP (stretched polypropylene), or the like is preferable.

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

The thickness of the coating layer is appropriately 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. Mu.m. The coating step is sufficiently carried out at room temperature, but for the purpose of reducing the viscosity and improving the workability, the resin composition may be heated in the range of 40 to 80 ℃.

The drying step may be performed after the coating step, or the subsequent heating step may be performed directly without the drying step. The drying step is performed for the purpose of removing the organic solvent. In the drying step, a suitable apparatus such as a heating plate, a box dryer, or a conveyor type dryer may be used. The drying step is preferably performed at 80 to 200 ℃, more preferably 100 to 150 ℃. The drying step is preferably performed for 1 minute to 10 hours, more preferably 3 minutes to 1 hour.

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

Then, 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 imidizing the polyimide precursor in the coating film to obtain a film made of polyimide.

The heating step may 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 sequentially.

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

The heating temperature may be appropriately set depending on the type of the organic solvent (b), and is preferably 250 to 500 ℃, more preferably 300 to 450 ℃. If the temperature is 250 ℃ or higher, imidization becomes sufficient, and if the temperature is 500 ℃ or lower, there are no problems such as a decrease in transparency and a deterioration in heat resistance of the obtained polyimide film. The heating time is preferably about 0.5 to 3 hours.

In this embodiment, the oxygen concentration of the surrounding 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 viewpoints of transparency and yellowness (YI value) of the obtained polyimide film. By heating in an atmosphere having an oxygen concentration of 2,000 mass ppm or less, the YI value of the obtained polyimide film can be set to 30 or less.

A peeling step of peeling the resin film from the support is required after the heating step, 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 modes (1) to (4).

(1) After the structure including the polyimide resin film and the support is produced by the above method, laser light is irradiated from the support side of the structure, and the interface between the support and the polyimide resin film is subjected to abrasion processing, thereby peeling the polyimide resin. Examples of the type of laser include a solid (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 patent application laid-open No. 2007-512568, japanese patent application laid-open No. 2012-511173, and the like).

(2) A method of forming a release layer on a support before applying a resin composition to the support, thereafter obtaining a structure comprising a polyimide resin film/release layer/support, and peeling the polyimide resin film. Examples of the method include a method using PARYLENE (registered trademark, manufactured by japan PARYLENE contract company) or tungsten oxide as the release layer; a method using a release agent such as a vegetable oil-based release agent, a silicone-based release agent, a fluorine-based release agent, or an aldehyde-based release agent (see, for example, JP-A2010-67957 and JP-A2013-179306).

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

(3) A method of obtaining a polyimide resin film by using an etchable metal substrate as a support, obtaining a structure including a polyimide resin film/support, and then etching a metal with an etchant. As the metal, copper (specifically, electrolytic copper foil "DFF" manufactured by mitsunobu metal mining corporation), aluminum, and the like can be used. As the etchant, ferric chloride or the like may be used for copper, and dilute hydrochloric acid or the like may be used for aluminum.

(4) The method of producing a structure comprising a polyimide resin film and a support by the above method comprises adhering an adhesive film to the surface of the polyimide resin film, separating the adhesive film and the polyimide resin film from the support, and separating the polyimide resin film from the adhesive film.

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

When copper is used as the support in the method (3), the resulting polyimide resin film tends to have a high yellowness (YI value) and a low elongation. This is considered to be the effect of copper ions.

The thickness of the resin film obtained by the above method is not particularly limited, but is preferably in the range of 1 to 100. Mu.m, more preferably 5 to 20. Mu.m.

The resin film of the present embodiment may have a yellowness (YI value) of 30 or less when the film thickness is 10. Mu.m. Further, the residual stress may be 25MPa or less. In particular, the yellowness (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 application is imidized under a nitrogen atmosphere (for example, in a nitrogen gas having an oxygen concentration of 2,000 mass ppm or less), preferably at 300 to 550 ℃, and more preferably at 350 to 450 ℃.

< laminate >

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

Another aspect of the present invention provides 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 may be carried out in the same manner as the method for producing the resin film, except that, for example, the peeling step is not carried out.

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

As described in more detail, the following will be described.

In forming a flexible display, a glass substrate is used as a support, and a flexible substrate is formed thereon, and further, TFTs and the like are formed 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 practice, in order to exhibit desired performance, it is necessary to form a TFT-IGZO (InGaZnO) oxide semiconductor or TFT (a-Si-TFT, poly-Si-TFT) using an inorganic material at a high temperature in the vicinity of 250 to 450 ℃. On the other hand, the polyimide film tends to be degraded in physical properties (particularly yellowness and elongation) due to these thermal histories, and if it exceeds 400 ℃, the yellowness and elongation are degraded, in particular. However, the polyimide film obtained from the polyimide precursor of the present invention has little decrease in yellowness and elongation in a high temperature range of 400 ℃ or higher, and can be used favorably in this range.

Further, in the present embodiment, a laminate including an LTPS (low temperature polysilicon TFT) layer and a polyimide 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 comprising the support and a polyimide resin film formed from 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 by 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 suitability of this annealing treatment can be confirmed by using a laminate in which a SiOx film is formed on a polyimide resin film and performing an annealing treatment at 450 ℃ (see < annealing evaluation of inorganic film/polyimide laminate > of one example described below). From the viewpoint of good annealing evaluation, 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, more preferably 0.1% or less. The reason why the annealing evaluation is better as the ratio of the structural unit M is smaller is not yet determined, and it is considered that: the decomposition of azo bonds (mainly present at the ends) contained in the polyimide precursor during the annealing treatment is involved in the generation of gas.

The laminate comprising an LTPS (low temperature polysilicon TFT) layer and a polyimide film layer comprising a polyimide represented by the general formula (3) has less peeling and swelling after a thermal cycle test and less warpage of a substrate.

Further, if the residual stress generated between the flexible substrate and the polyimide resin film is high, there is a possibility that the laminate of the flexible substrate and the polyimide resin film expands in a TFT process at a high temperature, and then, when the laminate contracts during normal temperature cooling, there is a possibility that the glass substrate will warp and break, and the flexible substrate will peel off from the glass substrate. In general, a glass substrate has a smaller thermal expansion coefficient than a resin, and thus, residual stress is generated between the glass substrate and a flexible substrate. As described above, the resin film according to the present embodiment can reduce the residual stress generated between glass substrates to 25MPa or less, and thus can be suitably used for forming a flexible display.

Further, the polyimide film of the present embodiment can have a yellowness (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, so that the yield in manufacturing a flexible display can be improved.

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

Accordingly, another aspect of the present invention provides a display substrate.

The method for manufacturing a display substrate according to the present embodiment is characterized by comprising 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, thereby forming 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 having the element or circuit formed thereon 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 the method for producing the resin film.

The element/circuit formation process may be performed by methods known to those skilled in the art.

The resin film of the present embodiment satisfying the above physical properties can be suitably used for applications where use is limited due to the yellow color of a conventional polyimide film, particularly for applications such as a colorless transparent substrate for a flexible display and a protective film for a color filter. Further, the present invention can be used in fields requiring colorless transparency and low birefringence, such as a light-diffusing sheet and a coating film (for example, an interlayer of a TFT-LCD, a gate insulating film, a liquid crystal alignment film, etc.), an ITO substrate for a touch panel, and a cover for a smart phone, instead of a resin substrate, for example, in a protective film, a TFT-LCD, etc. When the polyimide according to the present embodiment is used as 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 producing a display and a laminate will be described as an example of application of the polyimide film according to the present embodiment.

< method for manufacturing display >

The method for manufacturing the display 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 a support; a film forming step of heating the resin composition to form a polyimide resin film; an element forming step of forming an element on the polyimide resin film; and a peeling step of peeling the polyimide resin film formed with the element from the support.

Manufacturing example of Flexible organic EL display

Fig. 1 is a schematic view showing a structure of a top-emission flexible organic EL display, which is an example of the display of the present embodiment, above a polyimide substrate.

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

The manufacturing process of the flexible organic EL display includes the following steps: a step of producing a polyimide film on a glass substrate support and producing the organic EL substrate shown in fig. 1 on the polyimide film; a step of manufacturing a sealing substrate; an assembling step of adhering 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 process, the sealing substrate manufacturing process, and the assembling process may be applied to known manufacturing processes. Examples thereof are shown below, but are not limited thereto. The peeling step is the same as the polyimide film peeling step.

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 upper portion by a CVD method or a sputtering method, and a metal wiring layer for driving a TFT is formed on the upper portion by a photoresist or the like. An active buffer layer of SiO or the like is formed on the upper portion thereof by CVD, and a TFT device (TFT 256 in fig. 1) of metal oxide semiconductor (IGZO), low Temperature Polysilicon (LTPS) or the like is formed on the upper portion thereof. After manufacturing the TFT substrate for a flexible display, an interlayer insulating film 258 having 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 a lower electrode 259 is formed so as to be paired with the TFT.

Next, after the partition wall (bank) 251 is formed using photosensitive polyimide or the like, a hole transport layer 253 and a light emitting layer 254 are formed in each space defined by the partition wall. Further, an upper electrode (cathode) 255 is formed so as to cover the light emitting layer 254 and the partition wall (bank) 251. Thereafter, an organic EL material that emits red light (corresponding to the organic EL element 250a that emits red light in fig. 1), an organic EL material that emits green light (corresponding to the organic EL element 250b that emits green light in fig. 1), and an organic EL material that emits blue light (corresponding to the organic EL element 250c that emits blue light in fig. 1) are deposited by a known method using a fine metal mask or the like as a mask, thereby manufacturing an organic EL substrate. A top emission type flexible organic EL display can be manufactured by sealing an organic EL substrate with a sealing film or the like (sealing substrate 2b in fig. 1), and peeling a device above a polyimide substrate from a glass substrate support by a known peeling method such as laser peeling. When the polyimide according to the present embodiment is used, a flexible organic EL display of the bottom view type (see through) can be manufactured. In addition, a bottom emission type flexible organic EL display can be manufactured by a known method.

< manufacturing example of Flexible liquid Crystal display >

The polyimide film of the present embodiment can be used to fabricate a flexible liquid crystal display. Specifically, a polyimide film is formed on a glass substrate support by the above method, and a TFT substrate made of, for example, amorphous silicon, a metal oxide semiconductor (IGZO or the like), and low-temperature polysilicon is manufactured by the above method. In addition, according to the coating step and the film forming step of the present embodiment, a polyimide film is formed on the glass substrate support, and a color filter glass substrate (CF substrate) having the polyimide film is formed by using a color resist or the like according to a known method. A sealing material including a 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 lacking, and the other substrate has a diameter corresponding to the thickness of the liquid crystal layer, and spherical spacers made of plastic or silica are dispersed.

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 decompression method, a thermosetting resin is applied to a liquid crystal injection port, and the liquid crystal material is sealed by heating, thereby forming a liquid crystal layer. Finally, a flexible liquid crystal display can be manufactured by peeling the glass substrate on the CF side and the glass substrate on the TFT side at the interface between the polyimide film and the glass substrate by a laser peeling method or the like.

< 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 a support; a film forming step of heating the resin composition to form a polyimide resin film; and an element forming step of forming an element on the polyimide resin film.

As the element in the laminate, the element exemplified in the manufacture of the above-described flexible device can be exemplified. As the support, for example, a glass substrate can be used. The specific steps of the coating step and the film forming step are preferably the same as those described for the above-mentioned 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, for example, as a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, and the like, and can be particularly suitably used as a substrate in the production of flexible devices. Here, examples of flexible devices to which the resin film and the laminate of the present embodiment can be applied include flexible displays, flexible solar cells, flexible touch panel electrode substrates, flexible lighting, and flexible batteries.

Examples

The present invention will be described in further detail with reference to examples, but the scope of the present invention is not limited to the examples.

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

< determination 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 photo-pure chemical Co., ltd., for high performance liquid chromatography) was used, and 24.8mmol/L of lithium bromide monohydrate (manufactured by Fuji photo-pure chemical Co., ltd., purity: 99.5%) and 63.2mmol/L of phosphoric acid (manufactured by Fuji photo-pure chemical Co., ltd., for high performance liquid chromatography) were added and dissolved. The standard curve for calculating the weight average molecular weight was prepared using standard polystyrene (manufactured by the company of Emulation Type PS-1, agilent Technologies).

The device comprises: HLC-8220GPC (manufactured by Tosoh Co., ltd.)

Column: tsk gel Super HM-H (manufactured by Tosoh Co., ltd.)

Flow rate: 0.5 mL/min

Column temperature: 40 DEG C

A detector: UV-8220 (UV-Vis: ultraviolet visible absorptometer, manufactured by Tosoh Co., ltd.)

< evaluation of residual stress >

Each resin composition was applied to a 6-inch silicon wafer having a thickness of 625 μm.+ -. 25 μm, in which the "warpage" was measured in advance, by a spin coater, and baked at 100℃for 7 minutes. Thereafter, a silicon wafer having a polyimide resin film with a thickness of 10 μm after curing was produced by performing a heat curing treatment (curing treatment) at 430℃for 1 hour with a vertical curing oven (model name: VF-2000B, manufactured by Koyo Lindberg Co.) so that the oxygen concentration in the library became 10 mass ppm or less.

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

And (3) the following materials: the residual stress exceeds-5 MPa and is 15MPa or less (evaluation of residual stress "Excellent")

O: the residual stress exceeds 15MPa and is 25MPa or less (evaluation of residual stress "good")

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

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

A polyimide resin film was produced on a wafer on which alumina was vapor deposited in advance in the same manner as in the above < evaluation of residual stress >. Thereafter, the wafer was immersed in a dilute hydrochloric acid aqueous solution, and the polyimide resin film was peeled off, whereby a resin film was obtained.

The obtained polyimide resin film was measured for yellowness (YI value) and Haze (Haze value) (film thickness was converted to 10 μm) by using a D65 light source, using a Spectotometer (SE 600) manufactured by Nippon electric color industry Co.

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

For the resin composition prepared in the synthesis example,

after the concentration was adjusted to 1.0 mass%, a proper amount of water was added, and the mixture was heated at 80℃for 3 days to depolymerize the acid component and the amine component, thereby producing an acid monomer and an 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 determination.

LC：

The device comprises: waters Co., ltd., UPLC

Column: waters Co., ltd., ACQUITY UPLC HSS T, 3.1.8 um

(2.1mm I.D.×100mm)

And (3) detection: PDA 200-800nm

Flow rate: 0.2 mL/min

Mobile phase: a=water (0.1% hcooh)

B=acetonitrile (0.1% hcooh)

Injection amount: 1 mu L

MS：

The device comprises: waters corporation, synapt G2

Ionization: ESI+

The peak area of the PDA chromatogram at 300nm obtained by the LC/MS measurement was obtained, and the ratio (M/(L+M)) of the structural unit M to the total of the structural units L and 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 formula (2))/(peak area of amine component of formula (1) + (peak area of amine component of formula (2)) ]. Times.100. Cndot.cndot.1

< evaluation of laser peeling energy >

The resin compositions prepared in the examples and comparative examples were applied to a glass substrate (thickness: 0.7 mm) so that the film thickness became 10 μm after curing, and pre-baked at 80℃for 40 minutes. Thereafter, a laminate of the glass substrate and the polyimide resin film was produced by performing a heat curing treatment at 400℃for 1 hour with a vertical curing oven (model name: VF-2000B, manufactured by Koyo Lindberg Co.) so that the oxygen concentration in the reservoir became 10 mass ppm or less.

Irradiation was performed by using excimer laser (wavelength: 308 nm) while increasing irradiation energy stepwise from the glass substrate side of the laminate obtained as described above, with respect to the minimum irradiation energy capable of peeling polyimide and the increase of 10mJ/m at the minimum energy ² The ash (ash) at the time of irradiation with the obtained energy was evaluated. When no ash was produced, the measurement was marked as "O", when a small amount of ash was observed in depth, the measurement was marked as "delta", and when ash was observed in the whole area, the measurement was marked as "X".

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

< evaluation of annealing of inorganic film/polyimide laminate >

A silicon wafer having a polyimide resin film with a thickness of 10 μm after curing was produced in the same manner as in the above < evaluation of residual stress >, using the resin compositions of examples and comparative examples.

A SiOx film having a film thickness of 50nm was formed on the polyimide resin film by Chemical Vapor Deposition (CVD). The laminate thus obtained was subjected to an annealing treatment at 450℃for 30 minutes using a vertical curing oven (model name: VF-2000B, manufactured by Koyo Lindberg Co.) so that the oxygen concentration in the reservoir became 10 mass ppm or less.

After the annealing treatment, the surface of the SiOx film was observed by a laser microscope (model: VK-8700, manufactured by Kien's Co., ltd.) and the presence or absence of cracks in the annealing treatment was observed in a 10mm square field of view. The evaluation was performed 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)

To a 500ml separable flask replaced with nitrogen gas was charged 90.00g of N-methyl-2-pyrrolidone (NMP), 11.30g (49.5 mmol) of 4-aminophenyl-4-aminobenzoate (APAB), and 1.06mg (5.0 μm, l) of 4, 4-azobis-aniline (AzBz), and the mixture was stirred to dissolve APAB and AzBz. Then, 14.7g (50 mmol) of biphenyl-3, 3', 4' -tetracarboxylic dianhydride (BPDA) and 13.25g of N-methyl-2-pyrrolidone (NMP) were added thereto, and the mixture was adjusted so that the concentration of the polyamide acid became 20 mass%, and the mixture was subjected to polymerization under a nitrogen flow at 80℃for 3 hours with stirring. Thereafter, the 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 resulting polyamic acid was about 100,000.

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

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

The abbreviations of the components in table 1 are respectively defined as follows.

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

PMDA: pyromellitic dianhydride

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

TAHQ: para-phenylene bis (trimellitic anhydride)

DSDA:3,3', 4' -diphenyl sulfone tetracarboxylic dianhydride

ODPA:4,4' -Oxyphthalic anhydride

CpODA: cyclopentanone bisspiro norbornane tetracarboxylic dianhydride

APAB: 4-aminophenyl-4-aminobenzoate

2F-APAB: 2-fluoro-4-aminophenyl-4-aminobenzoate

3F-APAB: 3-fluoro-4-aminophenyl-4-aminobenzoate

3Me-APAB: 3-methyl-4-aminophenyl-4-aminobenzoate

44DAS:4,4' -diaminodiphenyl sulfone

BAFL:9, 9-bis (aminophenyl) fluorenes

DABA:4,4' -diaminobenzanilide

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

BAFL:9, 9-bis (aminophenyl) fluorenes

AzBz:4,4' -azobis-aniline

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

The varnishes obtained in each of the synthesis examples were directly used as resin compositions, and films were produced and evaluated in the manner described above (examples 1 to 24 and comparative examples 1 to 5). The evaluation results are shown in tables 2 and 3.

From tables 2 and 3 it is clear that: the polyimide film of comparative example 1 containing the structural unit represented by the general formula (2) at a ratio smaller than the range of one embodiment of the present invention with respect to the structural unit represented by the general formula (1) was unable to be peeled off by laser, and ash was generated. The polyimides of comparative examples 2 to 5 containing the structural unit represented by the general formula (2) in a ratio exceeding the range of one embodiment of the present invention have a large yellowness (YI value) and Haze (Haze value) with respect to the structural unit represented by the general formula (1).

On the other hand, the polyimide films of examples 1 to 24 containing the structural unit represented by the general formula (2) at a ratio ranging from 0.005 to 0.5% relative to the structural unit represented by the general formula (1) had a yellowness (YI value) as low as 30 or less, a residual stress as low as 20MPa or less, and a Haze (Haze value) as small as possible. In addition, no warpage or slight warpage occurs after forming the inorganic film. The content is more preferably 0.35% or less (examples 3 and 14) from the viewpoint of Haze (Haze value), and is more preferably 0.005% or more (examples 1, 13 and 15) from the viewpoint of laser peelability. Further, from the viewpoint of residual stress, it is more preferable to include 25 mol% or more of BPDA (examples 4 to 8), from the viewpoint of warp evaluation, it is preferable to include 20 mol% or more of APAB (examples 10 and 11), and from the viewpoint of yellowness (YI value), it is more preferable to include 10 mol% or more of BPAF, TAHQ, ODPA, cpODA (examples 4 to 8).

From the experimental results of table 2 above, it can be 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 method described in the examples, the concentration of the resin composition prepared in the synthesis example was adjusted to 1.0 mass%, then an appropriate amount of water was added, and the mixture was heated at 80℃for 3 days to depolymerize the acid component and the amine component, thereby obtaining an acid monomer and an amine monomer, and the acid monomer and the amine monomer were distilled off from the solvent to obtain a powder in which the acid monomer and the amine monomer were mixed, and a 1mg/mL acetonitrile solution was prepared for measurement by LC/MS. The content of each component was determined from the peak area of the dissolution 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, in the experimental results shown in the PDA chromatogram at 300nm, it was identified by MS (mass spectrometry) measurement: 4.07min (peak height: 15176803 count, peak area: 1473470.38 count) 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) derived from dimer of APAB having-NHNH-bond, 9.28min (peak height: 21195 count, peak area: 1058.44 count) derived from dimer of APAB having-n=n-bond. Using the peak areas of the structural units (APAB) represented by the general formula (1) and the structural units (2), the content is calculated by the calculation formula described in the above < evaluation method of the content (the ratio of the structural unit M to the total of the structural units L and M >). The content was 0.35%.

TABLE 1

TABLE 2

TABLE 3

TABLE 3 Table 3

TABLE 4

TABLE 4 Table 4

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Industrial applicability

The resin film formed from the polyimide precursor of the present invention can be used, for example, as a semiconductor insulating film, a TFT-LCD insulating film, an electrode protecting film, etc., and can be used particularly suitably as a substrate in the manufacture of flexible displays, substrates for ITO electrodes of touch panels, etc.

Claims

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

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

in the formula (2), X represents a 4-valent organic group, Y ₂ Represents a 2-valent organic group, Z represents-NHNH-or-N=N-,

y in the general formula (1) ₁ At least 1 selected from the group consisting of structures represented by the following general formulae (A-1) to (A-5), and

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

wherein R is ₁ ～R ₁₃ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, a to m are each independently an integer of 0 to 4, n is an integer of 1 or more, represents a bonding site,

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 is calculated by: after depolymerizing the polyimide precursor and separating the same into an acid component and an amine component, the polyimide precursor was separated into the amine component of the above general formula (1) and the amine component of the above general formula (2) by high performance liquid chromatography-mass spectrometry, and the peak areas in the photodiode array chromatogram in 300nm detection were determined, and the ratio of the peak areas (peak area of the amine component of the general formula (2)) to { (peak area of the amine component of the general formula (1) + (peak area of the amine component of the general formula (2)) } ×100% was used as a ratio.

2. The polyimide precursor according to claim 1, wherein the Y ₂ Is selected from the structures represented by the general formula (A-1) and the general formula (A-6)At least 1 of the group consisting of.

3. The polyimide precursor according to claim 1, wherein the amount of the structural unit M is 0.01 to 0.35 mol% relative to the total amount of the structural unit L and the structural unit M.

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

in the formula (1), X represents a 4-valent organic group, Y ₁ Represents an organic group having a valence of 2,

y in the general formula (1) ₁ At least 1 selected from the group consisting of structures represented by the following general formulae (A-1) to (A-3),

Wherein R is ₁ ～R ₈ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, and a to h each independently represents an integer of 0 to 4;

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

in the formula (A-6), R ₁₃ Each independently 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, 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) is a 4-valent group derived from at least 1 selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), 4 '-biphenylbis (trimellitic monoester anhydride) (TAHQ), 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF), 3',4 '-diphenyl sulfone tetracarboxylic dianhydride (DSDA), 4' -oxydiphthalic anhydride (ODPA) and cyclopentanone bisspironorbornane tetracarboxylic dianhydride (CpODA).

6. The polyimide precursor according to any one of claims 1 to 4, wherein the polyimide precursor has a weight average molecular weight Mw of 10,000 ～ 300,000.

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

8. The resin composition according to claim 7, wherein the proportion of the (a) polyimide precursor in the resin composition is 3 to 50 mass%.

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

10. The resin composition according to any one of claims 7 to 9, wherein a polyimide resin film obtained by curing the resin composition is used for flexible devices.

11. The resin composition of claim 10, wherein the flexible device is a flexible touch panel electrode substrate, a flexible lighting, or a flexible battery.

12. The resin composition of claim 10, wherein the flexible device is a flexible solar cell.

13. The resin composition according to any one of claims 7 to 9, wherein a polyimide resin film obtained by curing the resin composition is used for a flexible display.

14. The resin composition according to claim 13, wherein the flexible display is a flexible organic EL display.

15. A polyimide film obtained from the polyimide precursor according to any one of claims 1 to 6 or the resin composition according to any one of claims 7 to 14.

16. 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, Y ₁ And Y ₂ Each independently represents a 2-valent organic group, and l and m are each independently integers of 1 or more, wherein 0.01% or less m/(l+m) or less than 0.35% is satisfied;

the Y is ₁ At least 1 selected from the group consisting of structures represented by the following general formulae (A-1) to (A-5), and

the Y is ₂ At least 1 selected from the group consisting of structures represented by the following general formulae (A-1) and (A-6),

wherein R is ₁ ～R ₁₃ Each independently represents a 1-valent organic group having 1 to 20 carbon atoms or halogen, a to m are each independently an integer of 0 to 4, n is an integer of 1 or more, and represents a bonding site.

17. A method for producing 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 7 to 14 on a surface of a support;

and peeling the polyimide resin film from the support.

18. The method for producing a resin film according to claim 17, further comprising: and irradiating laser light from the support side before the step of peeling the polyimide resin film from the support.

19. A method for producing a laminate, comprising the steps of:

a step of forming a coating film by applying the resin composition according to any one of claims 7 to 14 on a surface of a support; and

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

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

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

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