JP2019014896A - Polyimide precursor, resin composition, resin film and manufacturing method thereof - Google Patents

Abstract

To provide a polyimide precursor, a polyimide resin film and a manufacturing method thereof, which realize low residual stress, little warpage, small yellowness (YI value) in a high-temperature region, and high extensibility.SOLUTION: A resin composition for a substrate of a low-temperature polysilicon TFT element comprises a polyimide precursor obtained by polymerizing a diamine component and an acid di-anhydride component, and a solvent, where the polyimide precursor (a) includes a structure represented by the general formula (1) in the figure.SELECTED DRAWING: None

Description

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

  In general, a polyimide resin film is used as a resin film for applications requiring high heat resistance. A general polyimide resin is prepared by preparing a polyimide precursor by solution polymerization of an aromatic carboxylic dianhydride and an aromatic diamine, and then thermally imidizing it at a high temperature or using a catalyst to form a chemical imide. It is a highly heat-resistant resin that is manufactured.

  Polyimide resin is an insoluble and infusible super heat resistant resin, and has excellent characteristics such as heat oxidation resistance, heat resistance, radiation resistance, low temperature resistance, and chemical resistance. For this reason, polyimide resins are used in a wide range of fields including electronic materials. Examples of application of polyimide resin in the field of electronic materials include insulating coating agents, insulating films, semiconductor protective films, and electrode protective films for TFT-LCDs. Recently, in place of a glass substrate conventionally used in the field of display materials, adoption as a colorless and transparent flexible substrate utilizing its lightness and flexibility has been studied.

  When manufacturing a polyimide resin film as a flexible substrate, a polyimide resin film is formed on a suitable support by applying a composition containing a polyimide precursor to form a coating film, followed by heat treatment and imidization. Get a film. As the support, for example, glass, silicon, silicon nitride, silicon oxide, metal or the like is used. When manufacturing the laminated body which has a polyimide film on such a support body, the heat processing in 250 degreeC or more are required for drying and imidation of a polyimide precursor. By this heat treatment, residual stress is generated in the laminate, and serious problems such as warpage and peeling occur. This is because the linear thermal expansion coefficient of polyimide is larger than that of the material constituting the support.

As a polyimide material having a small thermal expansion coefficient, a polyimide formed from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine is best known. Although depending on the film thickness and production conditions, it has been reported that this polyimide film exhibits a very low linear thermal expansion coefficient (Non-patent Document 1).
Moreover, since the polyimide which has ester structure in a molecular chain has moderate linearity and rigidity, it is reported that a low linear thermal expansion coefficient is shown (patent document 1).

However, general polyimide resins, including the polyimides described in the above documents, are colored brown or yellow due to a high aromatic ring density, and therefore have low light transmittance in the visible light region, and therefore colorless transparency is required. It is difficult to use in a certain field. For example, the polyimide of Non-Patent Document 1 obtained from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine has a yellowness (YI value) of 40 or more at a film thickness of 10 μm. High and colorless and transparent is insufficient.
About the yellowness of a film, it is known that the polyimide using the monomer which has a fluorine atom shows very low yellowness, for example (patent document 2).
Moreover, the polyimide precursor which has low yellowness and low Rth is disclosed (patent document 3).

Japanese Patent No. 4627297 Special table 2010-538103 gazette International Publication No. 2014/148441

Latest Polyimide Japan Polyimide Study Group NTS

By the way, in order to apply the polyimide resin as a colorless transparent flexible substrate, in addition to transparency, it is required that the residual stress with the substrate is small, the glass transition temperature is high, and the Rth (retardation) is low.
Conventionally, the process temperature was 350 ° C. or lower because the device type of a TFT produced for display display driving was amorphous silicon or IGZO.
On the other hand, recently, as the device type of TFT becomes low-temperature polysilicon (hereinafter referred to as LTPS), the process temperature becomes 400 ° C. or higher, and a film that exhibits the above physical properties even after such high-temperature heat history is desired. It is rare.

However, the physical properties of known transparent polyimides are not sufficient for use as heat-resistant colorless and transparent substrates for displays.
Furthermore, when this inventor confirmed, although the polyimide resin described in patent document 1 showed the low linear thermal expansion coefficient, the yellowness (YI value) of the polyimide resin film after peeling is large, It was found that there was a problem of high residual stress.
Regarding the yellowness, the polyimide films described in Patent Documents 2 and 3 show a low yellowness in a temperature range of about 300 ° C., but the yellowness (YI value) deteriorates significantly after a high temperature heat history of 400 ° C. or higher. I found out that

  The present invention has been made in view of the above-described problems. Therefore, the present invention is preferably used when the TFT device type is LTPS, and has a small yellowness (YI value) after high-temperature thermal history, a small residual stress with a glass substrate, a high glass transition temperature, and an Rth It aims at providing the polyimide resin film with low (retardation), its manufacturing method, and a laminated body.

で示される構造を含む、ことを特徴とする低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［２］
前記ポリイミド前駆体は、下記一般式（２）：

で示される構造を含む、［１］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［３］
前記ポリイミド前駆体の重量平均分子量が４万以上３０万以下である、［１］または［２］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［４］
前記樹脂組成物中に含まれる固形分の全重量を１００質量％としたときに、該固形分中に含有される、分子量１,０００未満の分子の量が５質量％未満である、［１］から［３］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［５］
前記固形分中に含有される、前記分子量１,０００未満の分子の量が１質量％以下である、［４］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［６］
前記ポリイミド前駆体は、前記ジアミン成分と前記酸二無水物成分の総質量を１００質量％としたときに、
下記式（３）：

（式中、複数存在するＲ３及びＲ４は、それぞれ独立に、炭素数１〜２０の一価の有機基であり、そしてｈは、３〜２００の整数である。）
で表される構造を含むシリコーンジアミン成分の含有量が６質量％未満である、［１］から［５］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［７］
前記シリコーンジアミン成分の含有量が５．９質量％以下である、［６］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［８］
前記シリコーンジアミン成分の含有量が３質量％以下である、［７］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［９］
前記ポリイミド前駆体は、前記ジアミン成分の総モル数を１００モル％としたときに、前記ポリイミド前駆体に含まれる、下記一般式（４）：

（式中、Ｒ_１、Ｒ_２、Ｒ_３はそれぞれ独立に炭素数１〜２０の１価の有機基を表す。ｎは０または１を表す。そしてａとｂとｃは０〜４の整数である。）
で表されるジアミンの量が４８モル％以下である、［１］〜［８］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１０］
前記ポリイミド前駆体に含まれる、前記一般式（４）で表されるジアミンの量が１モル％未満である、［９］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１１］
前記ポリイミド前駆体に含まれる、前記一般式（４）で表されるジアミンの量が０．９モル％以下である、［１０］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１２］
前記ポリイミド前駆体は、前記一般式（４）で表されるジアミン成分として、４−アミノフェニル−４−アミノベンゾエートを含む、［９］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１３］
前記ポリイミド前駆体は、前記ジアミン成分の総モル数を１００モル％としたときに、前記４−アミノフェニル−４−アミノベンゾエートの含有量が４８モル％以下である、［１］から［１２］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１４］
前記ポリイミド前駆体は、前記４−アミノフェニル−４−アミノベンゾエートの含有量が１モル％未満である、［１３］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１５］
前記ポリイミド前駆体は、前記４−アミノフェニル−４−アミノベンゾエートの含有量が０．９モル％未満である、［１４］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１６］
前記ポリイミド前駆体は、前記ジアミン成分として、ジアミノジフェニルスルホンを含む、［１］から［１５］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１７］
前記ポリイミド前駆体は、前記ジアミン成分の総モル数を１００モル％としたときに、前記ジアミノジフェニルスルホンの含有量が９０モル％以上である、［１６］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１８］
前記ポリイミド前駆体は、前記酸二無水物成分として、ピロメリット酸二無水物を含む、［１］から［１７］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［１９］
前記ポリイミド前駆体は、前記酸二無水物成分の総モル数を１００モル％としたときに、前記ピロメリット酸二無水物の含有量が９０モル％以上である、［１８］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［２０］
前記樹脂組成物を４３０℃で１時間加熱して得られるポリイミド膜の黄色度が、膜厚１０μｍにおいて２０以下である、［１］から［１９］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［２１］
前記樹脂組成物を４３０℃で１時間加熱して得られるポリイミド膜の黄色度が、膜厚１０μｍにおいて１３以下である、［２０］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［２２］
前記樹脂組成物を４３０℃で１時間加熱して得られるポリイミド膜のガラス転移温度が、３６０℃以上である、［１］から［２１］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［２３］
前記樹脂組成物を４３０℃で１時間加熱して得られるポリイミド膜のガラス転移温度が、４７０℃以上である、［２２］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［２４］
前記樹脂組成物を４３０℃で１時間加熱して得られるポリイミド膜のレタデーションが、膜厚１０μｍにおいて１０００ｎｍ以下である、［１］から［２３］のいずれかに記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［２５］
前記樹脂組成物を４３０℃で１時間加熱して得られるポリイミド膜のレタデーションが、膜厚１０μｍにおいて１４０ｎｍ以下である、［２４］に記載の低温ポリシリコンＴＦＴ素子の基板用の樹脂組成物。
［２６］
支持体の表面上に、［１］から［２５］のいずれかに記載の樹脂組成物を塗布する工程と、
前記樹脂組成物からポリイミド樹脂膜を形成する工程と、
前記ポリイミド樹脂膜を前記支持体から剥離する工程と、
を含むことを特徴とする、樹脂フィルムの製造方法。
［２７］
前記ポリイミド樹脂膜を前記支持体から剥離する工程に先立って、前記支持体側からレーザーを照射する工程を行う、請求項２６に記載の樹脂フィルムの製造方法。
［２８］
請求項［２６］又は［２７］に記載の方法により樹脂フィルムを製造する方法を含むディスプレイの製造方法。
［２９］
支持体の表面上に、［１］から［２５］のいずれかに記載の樹脂組成物を塗布する工程と、
前記樹脂組成物からポリイミド樹脂膜を形成する工程と、
前記ポリイミド樹脂膜上に低温ポリシリコンＴＦＴを形成する工程と、
を含む積層体の製造方法。
［３０］
前記ポリイミド樹脂膜を前記支持体から剥離する工程を、さらに含む、［２９］に記載の積層体の製造方法。
［３１］
［２９］又は［３０］に記載の積層体の製造方法を含むフレキシブルデバイスの製造方法。
［３２］
下記一般式（５）：

で表されるポリイミドを含むポリイミド層と、低温ポリシリコンＴＦＴ層と、を含むことを特徴とする積層体。
［３３］
前記ポリイミド層中に含まれる、分子量１,０００未満の分子の量が５質量％未満である、［３２］に記載の積層体。
［３４］
４３０℃で加熱した時の膜厚１０μｍにおける黄色度が２０以下であり、残留応力が２５ＭＰａ以下であり、伸度が１５％以上であることを特徴とする、ポリイミドフィルム。 The inventors of the present invention have made extensive studies to solve the above problems. As a result, it has been found that a polyimide resin film obtained by curing a resin composition containing a polyimide precursor having a specific structure has a small yellowness (YI value) in a high temperature region and a small residual stress with the substrate. In addition, when a laminate including a polyimide film having a specific structure and an LTPS layer is used as an organic EL device, there is no warpage, the lighting test is good, and the ash after laser peeling is found to be small. Based on these findings It came to make this invention.
That is, the present invention is as follows.
[1]
A resin composition for a substrate of a low-temperature polysilicon TFT element, comprising a polyimide precursor obtained by polymerizing a diamine component and an acid dianhydride component, and a solvent,
The polyimide precursor is
(A) The following general formula (1):

The resin composition for the board | substrates of the low-temperature polysilicon TFT element characterized by including the structure shown by these.
[2]
The polyimide precursor has the following general formula (2):

A resin composition for a substrate of a low-temperature polysilicon TFT element according to [1], comprising a structure represented by:
[3]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [1] or [2], wherein the polyimide precursor has a weight average molecular weight of 40,000 to 300,000.
[4]
When the total weight of solids contained in the resin composition is 100% by mass, the amount of molecules having a molecular weight of less than 1,000 contained in the solids is less than 5% by mass [1 ] The resin composition for the substrates of the low-temperature polysilicon TFT elements according to any one of [3].
[5]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [4], wherein the amount of the molecule having a molecular weight of less than 1,000 contained in the solid content is 1% by mass or less.
[6]
When the polyimide precursor has a total mass of the diamine component and the acid dianhydride component of 100% by mass,
Following formula (3):

(In the formula, a plurality of R3 and R4 are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200.)
The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of [1] to [5], wherein the content of the silicone diamine component having a structure represented by: is less than 6% by mass.
[7]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [6], wherein the content of the silicone diamine component is 5.9% by mass or less.
[8]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [7], wherein the content of the silicone diamine component is 3% by mass or less.
[9]
When the total number of moles of the diamine component is 100 mol%, the polyimide precursor is contained in the polyimide precursor and has the following general formula (4):

(Wherein R ₁ , R ₂ and R ₃ each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4) .)
The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of [1] to [8], wherein the amount of diamine represented by the formula is 48 mol% or less.
[10]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [9], wherein the amount of the diamine represented by the general formula (4) contained in the polyimide precursor is less than 1 mol%.
[11]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [10], wherein the amount of the diamine represented by the general formula (4) contained in the polyimide precursor is 0.9 mol% or less.
[12]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [9], wherein the polyimide precursor contains 4-aminophenyl-4-aminobenzoate as a diamine component represented by the general formula (4). .
[13]
[1] to [12], wherein the polyimide precursor has a content of 4-aminophenyl-4-aminobenzoate of 48 mol% or less when the total number of moles of the diamine component is 100 mol%. A resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of the above.
[14]
[13] The resin composition for a substrate of a low-temperature polysilicon TFT element according to [13], wherein the content of the 4-aminophenyl-4-aminobenzoate is less than 1 mol%.
[15]
[14] The resin composition for a substrate of a low-temperature polysilicon TFT element according to [14], wherein the content of the 4-aminophenyl-4-aminobenzoate is less than 0.9 mol%.
[16]
The said polyimide precursor is a resin composition for the board | substrates of the low-temperature polysilicon TFT element in any one of [1] to [15] containing diamino diphenyl sulfone as said diamine component.
[17]
The substrate of the low-temperature polysilicon TFT element according to [16], wherein the polyimide precursor has a content of the diaminodiphenylsulfone of 90 mol% or more when the total number of moles of the diamine component is 100 mol%. Resin composition.
[18]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of [1] to [17], wherein the polyimide precursor contains pyromellitic dianhydride as the acid dianhydride component.
[19]
The low temperature according to [18], wherein the content of the pyromellitic dianhydride is 90 mol% or more when the total number of moles of the acid dianhydride component is 100 mol%. A resin composition for a substrate of a polysilicon TFT element.
[20]
The low-temperature polysilicon TFT element according to any one of [1] to [19], wherein the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour has a yellowness of 20 or less at a film thickness of 10 μm. Resin composition for substrate.
[21]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [20], wherein the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour has a yellowness of 13 or less at a film thickness of 10 μm.
[22]
The substrate for the low-temperature polysilicon TFT element according to any one of [1] to [21], wherein the glass transition temperature of the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour is 360 ° C. or higher. Resin composition.
[23]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [22], wherein a glass transition temperature of a polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour is 470 ° C. or higher.
[24]
The substrate of the low-temperature polysilicon TFT element according to any one of [1] to [23], wherein the retardation of the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour is 1000 nm or less at a film thickness of 10 μm Resin composition.
[25]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [24], wherein a retardation of a polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour is 140 nm or less at a film thickness of 10 μm.
[26]
Applying the resin composition according to any one of [1] to [25] on the surface of the support;
Forming a polyimide resin film from the resin composition;
Peeling the polyimide resin film from the support;
A method for producing a resin film, comprising:
[27]
The manufacturing method of the resin film of Claim 26 which performs the process of irradiating a laser from the said support body side prior to the process of peeling the said polyimide resin film from the said support body.
[28]
A method for producing a display, comprising a method for producing a resin film by the method according to claim [26] or [27].
[29]
Applying the resin composition according to any one of [1] to [25] on the surface of the support;
Forming a polyimide resin film from the resin composition;
Forming a low-temperature polysilicon TFT on the polyimide resin film;
The manufacturing method of the laminated body containing this.
[30]
The method for producing a laminate according to [29], further comprising a step of peeling the polyimide resin film from the support.
[31]
[29] A method for producing a flexible device including the method for producing a laminate according to [30].
[32]
The following general formula (5):

The laminated body characterized by including the polyimide layer containing the polyimide represented by these, and a low-temperature polysilicon TFT layer.
[33]
The laminate according to [32], wherein the amount of molecules having a molecular weight of less than 1,000 contained in the polyimide layer is less than 5% by mass.
[34]
A polyimide film having a yellowness of 20 or less, a residual stress of 25 MPa or less, and an elongation of 15% or more when heated at 430 ° C. at a film thickness of 10 μm.

The polyimide film obtained from the resin composition according to the present invention has a small yellowness (YI value) in a high temperature region, a small residual stress with the substrate, a high glass transition temperature, and a low Rth (retardation).
Moreover, the laminated body containing the polyimide film obtained from the resin composition concerning this invention and a low-temperature polysilicon TFT has few curvature, a haze is low, and the result of a heat cycle test is favorable.

The figure which shows the organic electroluminescent structure which applied this invention to the organic electroluminescent board | substrate.

  Hereinafter, exemplary embodiments of the present invention (hereinafter abbreviated as “embodiments”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. Further, unless otherwise specified, the characteristic values described in the present disclosure are values measured by a method described in the section of [Example] or a method understood by those skilled in the art to be equivalent thereto. Intended.

<Resin composition>
The resin composition provided by one embodiment of the present invention contains (a) a polyimide precursor and (b) an organic solvent.
Hereinafter, each component will be described in order.

で示されるポリイミド前駆体である。
本実施の形態にかかる一般式（１）に用いられる酸二無水物としては、ピロメリット酸二無水物（以下ＰＭＤＡとも記す）を例示することができる。
本実施の形態にかかる一般式（１）に用いられるジアミンとしては、４，４’−ジアミノジフェニルスルホン、３，３’−ジアミノジフェニルスルホン、を例示することができる。
この中で、得られるポリイミドフィルムの残留応力、ＹＩ、ガラス転移温度、レタデーションＲｔｈ、伸度、ヘイズの観点から、下記一般式（２）で表される、４，４’−ジアミノジフェニルスルホンを用いた構造であることがより好ましい。

[Polyimide precursor]
The polyimide precursor in the present embodiment is
(A) The following general formula (1):

It is a polyimide precursor shown by these.
Examples of the acid dianhydride used in the general formula (1) according to this embodiment include pyromellitic dianhydride (hereinafter also referred to as PMDA).
Examples of the diamine used in the general formula (1) according to this embodiment include 4,4′-diaminodiphenylsulfone and 3,3′-diaminodiphenylsulfone.
Among these, 4,4′-diaminodiphenyl sulfone represented by the following general formula (2) is used from the viewpoints of residual stress, YI, glass transition temperature, retardation Rth, elongation, and haze of the obtained polyimide film. More preferably,

  The weight average molecular weight (Mw) of the polyimide precursor in the present embodiment is preferably 10,000 to 300,000, particularly preferably 40,000 to 300,000. When the weight average molecular weight is 40,000 or more, particularly excellent mechanical properties such as elongation and breaking strength, residual stress is low, and YI is low. When the weight average molecular weight is less than 300,000, it becomes easy to control the weight average molecular weight during synthesis of the polyamic acid, a resin composition having an appropriate viscosity can be obtained, and the coating property of the resin composition is improved. In the present disclosure, the weight average molecular weight is a value obtained as a standard polystyrene equivalent value using gel permeation chromatography (hereinafter also referred to as GPC).

  When the total weight of the solid content contained in the resin composition of the present embodiment is 100% by mass, the content of molecules having a molecular weight of less than 1,000 is preferably as small as possible. Specifically, it is preferably less than 5% by mass, preferably 4% by mass or less, preferably 3% by mass or less, preferably 2% by mass or less, and 1% by mass or less, based on the total weight of the solid content. Preferably, 0.5 mass% or less is preferable, 0.1 mass% or less is preferable, 0.05 mass% or less is preferable, and 0.02 mass% or less is preferable.

  Such a composition is excellent in viscosity stability and varnish coatability. In addition, a polyimide film obtained from such a composition is preferable because of low residual stress, low YI, high glass transition temperature (Tg), low retardation Rth, and high elongation. In addition, a laminate including such a polyimide film and a low-temperature polysilicon TFT has little warpage, low haze, and good heat cycle test results. The content of molecules having a molecular weight of less than 1,000 can be calculated from a peak area obtained by performing GPC measurement on the resin composition.

As the polyimide precursor in the present embodiment, other acid dianhydrides can be used in addition to pyromellitic dianhydride as long as the elongation, strength, stress, yellowness and the like are not impaired.
As such acid dianhydrides, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-cyclohexene-1,2 Dicarboxylic anhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone Tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2 ′, 3 , 3′-biphenyltetracarboxylic dianhydride, methylene-4,4′-diphthalic dianhydride, 1,1-ethylidene-4,4′-diphthalic dianhydride, 2,2-propylidene-4, 4′-diphthalic dianhydride, , 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, 4,4′-oxydiphthalic dianhydride, p-phenylenebis (trimellitic acid anhydride), thio-4,4′-diphthalic acid Dianhydride, sulfonyl-4,4′-diphthalic dianhydride, 1,3-bis (3,4-dicarboxyphenyl) benzene dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) Benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,3-bis [2- (3,4-dicarboxyphenyl) -2-propyl] benzene dianhydride 1,4-bis [2- (3,4-dicar Xylphenyl) -2-propyl] benzene dianhydride, bis [3- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, bis [4- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride 2,2-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) -1,1,3,3-tetramethyldisiloxane dianhydride, 2,3 , 6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3, Illustrate 4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, etc. Can do.

The content of the other acid dianhydrides in the total acid dianhydrides is preferably 20 mol% or less, more preferably 10 mol% or less, and particularly preferably 0 mol%.
The content of pyromellitic dianhydride in the total acid dianhydride is preferably 90 mol% or more, preferably 95 mol% or more, preferably 98 mol% or more, preferably 99 mol% or less, 99.5 More than mol% is preferable. The larger the amount of pyromellitic dianhydride in the total acid dianhydride, the more preferable in terms of YI, glass transition temperature Tg, and elongation.

In the polyimide precursor in the present embodiment, in addition to 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, as long as the elongation, strength, stress, yellowness and the like are not impaired, Other diamines can be used.
Examples of other diamines include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, and 4,4′-. Diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenylmethane 3,4′-diaminodiphenylmethane, 3,3′-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, 4,4-bis (4-aminophenoxy) biphenyl, 4,4-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (3-amino Phenoxy) phenyl] ether, 1,4-bis (4-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 9,10-bis (4-aminophenyl) anthracene, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl) propane, 2,2-bis [4- ( 4-aminophenoxy) phenyl) hexafluoropropane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, etc. Can, it is preferable to use one or more selected from these.

The content of other diamines in the total diamine is preferably 20 mol% or less, more preferably 10 mol% or less, and particularly preferably 0 mol%.
The content of diaminodiphenyl sulfone in all diamines is preferably 90 mol% or more, preferably 95 mol% or more, preferably 98 mol% or more, preferably 99 mol% or more, and preferably 99.5 mol% or more. The larger the amount of diaminodiphenylsulfone, the better from the viewpoint of residual stress, YI, glass transition temperature Tg, retardation Rth, and elongation. As the diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone is preferable.

（式中、Ｒ_１、Ｒ_２、Ｒ_３はそれぞれ独立に炭素数１〜２０の１価の有機基を表す。ｎは０または１を表す。そしてａとｂとｃは０〜４の整数である。） When the total number of moles of the diamine component is 100 mol%, the amount of diamine represented by the following general formula (4) contained in the polyimide precursor is preferably 48 mol% or less.

(Wherein R ₁ , R ₂ and R ₃ each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4) .)

  Examples of the diamine represented by the general formula (4) include, when n is 0, 4-aminophenyl-4-aminobenzoate (APAB), 2-methyl-4-aminophenyl-4-aminobenzoate (ATAB). 4-aminophenyl-3-aminobenzoate (4,3-APAB) and the like. When n is 1, [4- (4-aminobenzoyl) oxyphenyl] 4-aminobenzoate and the like can be exemplified.

Particularly, the polyimide precursor is 4-aminophenyl-4-amino contained in the polyimide precursor when the total number of moles of the diamine component is 100 mol% as the diamine component represented by the general formula (4). The benzoate content is preferably 48 mol% or less. The effects of low YI, high Tg, low retardation, and high elongation can be obtained. 4-aminophenyl-4-aminobenzoate may or may not be included.
The smaller the amount of the diamine represented by the general formula (4), the more preferable from the viewpoints of YI, glass transition temperature Tg, retardation Rth, and elongation.

The amount of the diamine represented by the general formula (4) contained in the polyimide precursor is preferably 30 mol% or less, preferably 20 mol% or less, preferably 10 mol% or less, and preferably 5 mol% or less.
The amount of the diamine represented by the general formula (4), particularly, for example, 4-aminophenyl-4-aminobenzoate is preferably less than 1 mol%, preferably 0.9 mol% or less, and 0.8 mol% or less. Is preferable, 0.6 mol% or less is preferable, 0.4 mol% or less is preferable, 0.2 mol% or less is preferable, and 0.1 mol% or less is preferable.

（式中、複数存在するＲ_３及びＲ_４は、それぞれ独立に、炭素数１〜２０の一価の有機基であり、そしてｈは、３〜２００の整数である。）
で表される構造を含むシリコーンジアミン成分の含有量が６質量％未満であることが好ましい。 The polyimide precursor is
When the total mass of the diamine component and the acid dianhydride component is 100% by mass,
Following formula (3):

(In the formula, a plurality of R ₃ and R ₄ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200.)
It is preferable that content of the silicone diamine component containing the structure represented by is less than 6 mass%.

  The smaller the silicone diamine component containing the structure represented by the above formula (3), the smaller YI, the larger the glass transition temperature Tg, and the smaller the retardation Rth, which is preferable. The content of the silicone diamine component including the structure represented by the above formula (3) is preferably 5.9% by mass or less, 5.5% by mass or less, and 5.0% by mass or less. 0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, 1.0% by mass or less, 0.5% by mass or less, 0.4% by mass or less Yes, 0.3 mass% or less, 0.2 mass% or less, 0.1 mass% or less, 0.08 mass% or less, 0.06 mass% or less, 0.04 mass% or less It is not more than mass% and is not more than 0.02 mass%.

In the range which does not impair the performance, the polyimide precursor in an embodiment is good also as a polyamidoimide precursor by using dicarboxylic acid in addition to the above-mentioned tetracarboxylic dianhydride. By using such a precursor, various performances such as improvement of mechanical elongation, improvement of glass transition temperature, reduction of yellowness, etc. can be adjusted in the obtained film. Examples of such dicarboxylic acids include dicarboxylic acids having an aromatic ring and alicyclic dicarboxylic acids. In particular, it is preferably at least one 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 carbons herein includes the number of carbons contained in the carboxyl group.
Of these, dicarboxylic acids having an aromatic ring are preferred.

  Specifically, for example, isophthalic acid, terephthalic acid, 4,4′-biphenyldicarboxylic acid, 3,4′-biphenyldicarboxylic acid, 3,3′-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3 -Naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-sulfonylbisbenzoic acid, 3,4'-sulfonylbisbenzoic acid, 3,3'-sulfonylbisbenzoic acid 4,4′-oxybisbenzoic acid, 3,4′-oxybisbenzoic acid, 3,3′-oxybisbenzoic acid, 2,2-bis (4-carboxyphenyl) propane, 2,2-bis (3-carboxy Phenyl) propane, 2,2′-dimethyl-4,4′-biphenyldicarboxylic acid, 3,3′-dimethyl-4,4′-biphenyldicarbo Acid, 2,2′-dimethyl-3,3′-biphenyldicarboxylic acid, 9,9-bis (4- (4-carboxyphenoxy) phenyl) fluorene, 9,9-bis (4- (3-carboxyphenoxy) Phenyl) fluorene, 4,4′-bis (4-carboxyphenoxy) biphenyl, 4,4′-bis (3-carboxyphenoxy) biphenyl, 3,4′-bis (4-carboxyphenoxy) biphenyl, 3,4 ′ -Bis (3-carboxyphenoxy) biphenyl, 3,3'-bis (4-carboxyphenoxy) biphenyl, 3,3'-bis (3-carboxyphenoxy) biphenyl, 4,4'-bis (4-carboxyphenoxy) -P-terphenyl, 4,4'-bis (4-carboxyphenoxy) -m-terphenyl, 3,4'-bis (4-carboxy Boxyphenoxy) -p-terphenyl, 3,3′-bis (4-carboxyphenoxy) -p-terphenyl, 3,4′-bis (4-carboxyphenoxy) -m-terphenyl, 3,3 ′ -Bis (4-carboxyphenoxy) -m-terphenyl, 4,4'-bis (3-carboxyphenoxy) -p-terphenyl, 4,4'-bis (3-carboxyphenoxy) -m-terphenyl, 3,4′-bis (3-carboxyphenoxy) -p-terphenyl, 3,3′-bis (3-carboxyphenoxy) -p-terphenyl, 3,4′-bis (3-carboxyphenoxy) -m -Terphenyl, 3,3'-bis (3-carboxyphenoxy) -m-terphenyl, 1,1-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4,4′-benzophenone dicarboxylic acid, 1,3-phenylenediacetic acid, 1,4-phenylenediacetic acid and the like; and 5-aminoisophthale described in WO 2005/068535 pamphlet Examples include acid derivatives. When these dicarboxylic acids are actually copolymerized with a polymer, they may be used in the form of an acid chloride form, an active ester form or the like derived from thionyl chloride or the like.

[Production of polyimide precursor]
The polyimide precursor (polyamic acid) of the present invention comprises pyromellitic dianhydride and a diamine (for example, 4,4′-diaminodiphenylsulfone) used in the structural unit represented by the general formula (1). Can be synthesized by polycondensation reaction. This reaction is preferably carried out in a suitable solvent. Specifically, for example, after dissolving a predetermined amount of 4,4′-DAS in a solvent, a predetermined amount of pyromellitic dianhydride is added to the obtained diamine solution and stirred.

When the polyimide precursor is synthesized, the ratio (molar ratio) of the tetracarboxylic dianhydride component to the diamine component is determined by the thermal linear expansion coefficient, residual stress, elongation, and yellowness (hereinafter referred to as YI) of the obtained resin film. From the viewpoint of controlling the desired range of tetracarboxylic dianhydride: diamine = 100: 90 to 100: 110 (diamine 0.90 to 1.0.1 relative to 1 mol part of tetracarboxylic dianhydride). 10 mol parts), preferably 100: 95 to 100: 105 (0.95 to 1.05 mol parts of diamine with respect to 1 mol part of acid dianhydride).
In this embodiment, when synthesizing a polyamic acid which is a preferable polyimide precursor, the molecular weight is controlled by adjusting the ratio of the tetracarboxylic dianhydride component and the diamine component and adding a terminal blocking agent. It is possible. The molecular weight of the polyamic acid can be increased as the ratio of the acid dianhydride component to the diamine component is closer to 1: 1 and as the amount of the end-capping agent used is smaller.
It is recommended to use high-purity products as the tetracarboxylic dianhydride component and the diamine component. The purity is preferably 98% by mass or more, more preferably 99% by mass or more, and still more preferably 99.5% by mass or more. When using multiple types of acid dianhydride components or diamine components in combination, it is sufficient if the acid dianhydride component or diamine component has the above purity as a whole, but all types of acid dianhydrides used It is preferable that the component and the diamine component each have the above-described purity.

式中、Ｒ_１２＝メチル基で表されるエクアミドＭ１００（商品名：出光興産社製）、及び、Ｒ_１２＝ｎ−ブチル基で表されるエクアミドＢ１００（商品名：出光興産社製）等のアミド系溶媒；
γ−ブチロラクトン、γ−バレロラクトン等のラクトン系溶媒；
ヘキサメチルホスホリックアミド、ヘキサメチルホスフィントリアミド等の含りん系アミド系溶媒；
ジメチルスルホン、ジメチルスルホキシド、スルホラン等の含硫黄系溶媒；
シクロヘキサノン、メチルシクロヘキサノン等のケトン系溶媒；
ピコリン、ピリジン等の３級アミン系溶媒；
酢酸（２−メトキシ−１−メチルエチル）等のエステル系溶媒
等が：
前記フェノ−ル系溶媒として、例えば、フェノ−ル、ｏ−クレゾ−ル、ｍ−クレゾ−ル、ｐ−クレゾ−ル、２，３−キシレノ−ル、２，４−キシレノ−ル、２，５−キシレノ−ル、２，６−キシレノ−ル、３，４−キシレノ−ル、３，５−キシレノ−ル等が：
前記エ−テル及びグリコ−ル系溶媒として、例えば、１，２−ジメトキシエタン、ビス（２−メトキシエチル）エ−テル、１，２−ビス（２−メトキシエトキシ）エタン、ビス［２− （２−メトキシエトキシ）エチル］エ−テル、テトラヒドロフラン、１，４−ジオキサン等が、
それぞれ挙げられる。 The solvent for the reaction is not particularly limited as long as it is a solvent that can dissolve the tetracarboxylic dianhydride component and the diamine component, and the resulting polyamic acid, and obtain a high molecular weight polymer. Specific examples of such solvents include aprotic solvents, phenolic solvents, ethers and glycolic solvents. Specific examples thereof include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N-methyl as the aprotic solvent. Caprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, the following general formula (7):

_Wherein Ekuamido M100 represented by _{R 12} = methyl group (trade name: manufactured by Idemitsu Kosan Co., Ltd.), _and, Ekuamido B100 represented by _R 12 = n-butyl group (trade name: manufactured by Idemitsu Kosan Co., Ltd.), such as An amide solvent;
Lactone solvents such as γ-butyrolactone and γ-valerolactone;
Phosphorus-containing amide solvents such as hexamethylphosphoric amide and hexamethylphosphine triamide;
Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, 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) include:
Examples of the phenol solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2, 5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol and the like:
Examples of the ether and glycol solvents include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, and bis [2- ( 2-methoxyethoxy) ethyl] ether, tetrahydrofuran, 1,4-dioxane, etc.
Each is listed.

60-300 degreeC is preferable, as for the boiling point in the normal pressure of the solvent used for the synthesis | combination of a polyamic acid, 140-280 degreeC is more preferable, and 170-270 degreeC is especially preferable. When the boiling point of the solvent is higher than 300 ° C., a drying process is required for a long time. On the other hand, if the boiling point of the solvent is lower than 60 ° C., the surface of the resin film may be roughened during the drying process, bubbles may be mixed into the resin film, and a uniform film may not be obtained.
As described above, it is preferable to use a solvent having a boiling point of 170 to 270 ° C., more preferably a vapor pressure of 20 Pa or less at 20 ° C. from the viewpoint of solubility and edge repelling during coating. More specifically, it is preferable to use one or more selected from the group consisting of N-methyl-2-pyrrolidone, γ-butyrolactone, and the compound represented by the general formula (5).
The water content in the solvent is preferably 3000 ppm by mass or less.
These solvents may be used alone or in combination of two or more.

In the resin composition in the present embodiment, the content of molecules having a molecular weight of less than 1,000 is preferably less than 5% by mass.
The reason why the molecules having a molecular weight of less than 1,000 are present in the resin composition is considered to be due to the water content of the solvent and raw materials (acid dianhydride, diamine) used during the synthesis. That is, it is considered that the acid anhydride group of some acid dianhydride monomers is hydrolyzed by moisture to become a carboxyl group and remains in a low molecular weight state without increasing its molecular weight. Therefore, the water content of the solvent used for the above polymerization reaction should be as small as possible. The water content of this solvent is preferably 3,000 mass ppm or less, more preferably 1,000 mass ppm or less.
The amount of water contained in the raw material is also preferably 3000 ppm by mass or less, and more preferably 1000 ppm by mass or less.

  The water content of the solvent includes the grade of solvent used (dehydration grade, general-purpose grade, etc.), solvent container (bottle, 18L can, canister can, etc.), solvent storage status (whether or not rare gas is sealed, etc.), from opening to use (Such as use immediately after opening or use after lapse of time after opening) and the like. In addition, it is considered that the rare gas replacement in the reactor before the synthesis, the presence or absence of a rare gas flow during the synthesis, and the like are also involved. Therefore, when synthesizing (a) a polyimide precursor, a high-purity product is used as a raw material, a solvent with a small amount of water is used, and measures are taken to prevent moisture from the environment from entering the system before and during the reaction. It is recommended.

When each monomer component is dissolved in the solvent, it may be heated as necessary.
(A) It is preferable that the reaction temperature at the time of a polyimide precursor synthesis | combination shall be 0 degreeC-120 degreeC, More preferably, it is 40 degreeC-100 degreeC, More preferably, it is 60-100 degreeC. By performing the polymerization reaction at this temperature, a polyimide precursor having a high degree of polymerization can be obtained. The polymerization time is preferably 1 to 100 hours, and more preferably 2 to 10 hours. By setting the polymerization time to 1 hour or more, a polyimide precursor having a uniform polymerization degree can be obtained, and by setting the polymerization time to 100 hours or less, a polyimide precursor having a high polymerization degree can be obtained.

The polyimide precursor concerning this Embodiment can contain another polyimide precursor as long as the desired performance of this invention is not impaired as needed.
As such a polyimide precursor, the polyimide precursor obtained by polycondensing the other acid dianhydride and other diamine mentioned above can be illustrated, for example.
The mass ratio of the other polyimide precursor according to this embodiment is preferably 30% by mass or less, and preferably 10% by mass or less, based on the total of (a) the polyimide precursor. From the viewpoint of lowering the oxygen dependency of the light transmittance, it is more preferable.

In a preferred aspect of the present embodiment, (a) the polyimide precursor may be partially imidized. In this case, the imidization rate is preferably 80% or less, and more preferably 50% or less. This partial imidization can be obtained by heating the above polyimide precursor (a) and dehydrating and closing the ring. This heating is preferably 120 to 200 ° C., more preferably 150 to 180 ° C., and preferably 15 minutes to 20 hours, more preferably 30 minutes to 10 hours.
In addition, N, N-dimethylformamide dimethyl acetal or N, N-dimethylformamide diethyl acetal is added to the polyamic acid obtained by the above reaction and heated to esterify part or all of the carboxylic acid. By using it as the (a) polyimide precursor in the present embodiment, a resin composition having improved viscosity stability during storage at room temperature can be obtained. In addition to these ester-modified polyamic acids, the above acid dianhydride component is sequentially reacted with one equivalent of a monohydric alcohol with respect to the acid anhydride group and a dehydration condensing agent such as thionyl chloride or dicyclohexylcarbodiimide. Thereafter, it can also be obtained by a condensation reaction with a diamine component.

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

実施の態様におけるポリイミド前駆体は、重量平均分子量が４万以上３０万以下であり、かつ重量平均分子量１０００未満の分子の含有量が５質量％未満であれば限定されない。このようなポリイミド前駆体を得るためには、溶媒や原料における水分含量を特定の範囲以下にすることにより、かつ原料の純度を高め、酸二無水物とジアミンとのモル比を特定の範囲内にすることにより、達成することができる。
具体的には、溶媒中の水分含量は、３０００ｐｐｍ以下が好ましく、１５００ｐｐｍ以下がより好ましく、５００ｐｐｍ以下が特に好ましい。
原料の純度は９８質量％以上が好ましく、９９質量％以上がより好ましく、９９．５質量％以上が特に好ましい。
テトラカルボン酸二無水物：ジアミン＝１００：９０〜１００：１１０（テトラカルボン酸二無水物１モル部に対してジアミン０．９０〜１．１０モル部）の範囲とすることが好ましく、１００：９５〜１００：１０５（酸二無水物１モル部に対してジアミン０．９５〜１．０５モル部）の範囲とすることが更に好ましい。
上記ポリイミド前駆体は、得られるポリイミドフィルムのヘイズおよび伸度の観点から、下記一般式（２）で表される構造であることが好ましい。

As a second aspect of the present embodiment, the content of a molecule represented by the following general formula (1), having a weight average molecular weight of 40,000 or more and 300,000 or less and having a weight average molecular weight of less than 1,000 is less than 5% by mass. Certain polyimide precursors can be provided.

The polyimide precursor in the embodiment is not limited as long as the weight average molecular weight is 40,000 or more and 300,000 or less and the content of molecules having a weight average molecular weight of less than 1000 is less than 5% by mass. In order to obtain such a polyimide precursor, the water content in the solvent or the raw material is set to a specific range or less, the purity of the raw material is increased, and the molar ratio of the acid dianhydride and the diamine is within a specific range. This can be achieved.
Specifically, the water content in the solvent is preferably 3000 ppm or less, more preferably 1500 ppm or less, and particularly preferably 500 ppm or less.
The purity of the raw material is preferably 98% by mass or more, more preferably 99% by mass or more, and particularly preferably 99.5% by mass or more.
Tetracarboxylic dianhydride: diamine = 100: 90 to 100: 110 (diamine 0.90 to 1.10 mol part relative to 1 mol part of tetracarboxylic dianhydride) is preferable. More preferably, it is in the range of 95 to 100: 105 (0.95 to 1.05 mole part of diamine with respect to 1 mole part of acid dianhydride).
It is preferable that the said polyimide precursor is a structure represented by following General formula (2) from a haze and elongation viewpoint of the polyimide film obtained.

  Even if the polyimide precursor has a structure represented by the general formula (1) (preferably the general formula (2)), even if the yellowness is 20 or less and the residual stress is 25 MPa or less, the elongation is further increased. A polyimide film satisfying 15% or more cannot be provided. In this embodiment, in addition to having the structure represented by the general formula (1), the content of molecules having a weight average molecular weight of 40,000 or more and 300,000 or less and a weight average molecular weight of less than 1,000 is 5% by mass. By using a polyimide precursor that is less than this, a polyimide film that further satisfies the elongation can be provided. Specifically, a polyimide film having a yellowness of 20 or less at a film thickness of 10 microns after heating at 430 ° C., a residual stress of 25 MPa or less, and an elongation of 15% or more can be provided. .

<Resin composition>
Another aspect of the present invention provides a resin composition containing the aforementioned (a) polyimide precursor and (b) an organic solvent. This resin composition is typically a varnish.

[(B) Organic solvent]
The (b) organic solvent in the present embodiment is not particularly limited as long as it can dissolve the aforementioned (a) polyimide precursor and other optional components. As such (b) organic solvent, those described above as the solvent that can be used in the synthesis of (a) the polyimide precursor can be used. Preferred organic solvents are also the same as described above. The (b) organic solvent in the resin composition of the present embodiment may be the same as or different from the solvent used for the synthesis of (a) the polyimide precursor.
(B) It is preferable to make the organic solvent into an amount such that the solid content concentration of the resin composition is 3 to 50% by mass. Moreover, it is preferable to add after adjusting the structure and quantity of the (b) organic solvent so that the viscosity (25 degreeC) of a resin composition may be set to 500 mPa * s-100,000 mPa * s.

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

((C) surfactant)
By adding a surfactant to the resin composition of the present embodiment, the applicability of the resin composition can be improved. Specifically, the generation of streaks in the coating film can be prevented.
Examples of such surfactants include silicone surfactants, fluorosurfactants, and other nonionic surfactants. Examples of these include silicone surfactants such as organosiloxane polymers KF-640, 642, 643, KP341, X-70-092, X-70-093, (trade name, Shin-Etsu Chemical Co., Ltd.). Manufactured), SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (trade name, manufactured by Toray Dow Corning Silicone), SILWET L-77 , L-7001, FZ-2105, FZ-2120, FZ-2154, FZ-2164, FZ-2166, L-7604 (above, trade name, manufactured by Nihon Unicar), DBE-814, DBE-224, DBE- 621, CMS-626, CMS-222, KF-352A, KF-354L, KF-355A, KF-6020, DB E-821, DBE-712 (Gelest), BYK-307, BYK-310, BYK-378, BYK-333 (above, trade name, manufactured by Big Chemie Japan), granol (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), etc. ;
Examples of the fluorine-based surfactant include Megafac F171, F173, R-08 (trade name, manufactured by Dainippon Ink & Chemicals, Inc.), Fluorard FC4430, FC4432 (tradename, Sumitomo 3M Co., Ltd.);
Examples of nonionic surfactants other than these include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, and the like.

Among these surfactants, silicone surfactants and fluorine surfactants are preferable from the viewpoint of coating properties (streaks suppression) of the resin composition. From the viewpoint of influence on the rate, a silicone-based surfactant is preferable.
(C) When using surfactant, the compounding quantity has preferable 0.001-5 mass parts with respect to 100 mass parts of (a) polyimide precursors in a resin composition, and 0.01-3 mass parts. Is more preferable.

(D) Alkoxysilane compound In order to make the resin film obtained from the resin composition according to the present embodiment exhibit sufficient adhesion to a support in a production process such as a flexible device, the resin composition A thing can contain 0.01-20 mass% of alkoxysilane compounds with respect to 100 mass% of (a) polyimide precursor. When the content of the alkoxysilane compound with respect to 100% by mass of the polyimide precursor is 0.01% by mass or more, good adhesion to the support can be obtained. Moreover, it is preferable from a viewpoint of the storage stability of a resin composition that content of an alkoxysilane compound is 20 mass% or less. The content of the alkoxysilane compound is more preferably 0.02 to 15% by mass, still more preferably 0.05 to 10% by mass, with respect to 100 parts by mass of the polyimide precursor, It is especially preferable that it is 8 mass%.
By using an alkoxysilane compound as an additive of the resin composition according to the present embodiment, in addition to the above improvement of adhesion, the coating property of the resin composition (suppressing unevenness) is further improved and obtained. The curing oxygen concentration dependency of the YI value of the cured film can be reduced.

  Examples of the alkoxysilane compound include 3-ureidopropyltriethoxysilane, bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltripropoxysilane, γ-aminopropyltributoxysilane, γ-aminoethyltriethoxysilane, γ-aminoethyltripropoxysilane, γ-aminoethyltributoxysilane, γ-aminobutyltriethoxysilane, γ- Aminobutyltrimethoxysilane, γ-aminobutyltripropoxysilane, γ-aminobutyltributoxysilane, phenylsilanetriol, trimethoxyphenylsilane, trimethoxy (p-tolyl) silane, diphenylsilanediol , Dimethoxydiphenylsilane, diethoxydiphenylsilane, dimethoxydi-p-tolylsilane, triphenylsilanol, and alkoxysilane compounds represented by the following structures, respectively, and one or more selected from these compounds should be used: Is preferred.

The method for producing the resin composition in the present embodiment is not particularly limited. For example, the following method can be used.
When (a) the solvent used when synthesizing the polyimide precursor and (b) the organic solvent are the same, the synthesized polyimide precursor solution can be used as it is as the resin composition. In addition, if necessary, at least one of (b) an organic solvent and other components is added to the polyimide precursor in a temperature range of room temperature (25 ° C.) to 80 ° C., and the mixture is stirred and mixed. You may use as a thing. For this stirring and mixing, an appropriate device such as a three-one motor (manufactured by Shinto Chemical Co., Ltd.) equipped with a stirring blade, a rotation and revolution mixer, or the like can be used. Moreover, you may add a 40-100 degreeC heat | fever as needed.

  On the other hand, when (a) the solvent used when synthesizing the polyimide precursor is different from (b) the organic solvent, the solvent in the synthesized polyimide precursor solution may be reprecipitated, e.g. After removing by an appropriate method (a) isolating the polyimide precursor, (b) adding an organic solvent and other components as necessary in a temperature range of room temperature to 80 ° C., and stirring and mixing. Thus, a resin composition may be prepared.

  After preparing the resin composition as described above, a part of the polyimide precursor is dehydrated to such an extent that the polymer does not precipitate by heating the composition solution at 130 to 200 ° C., for example, for 5 minutes to 2 hours. It may be imidized. 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 when stored at room temperature can be improved. The imidation ratio is preferably 5% to 70% from the viewpoint of balancing the solubility of the polyimide precursor in the resin composition solution and the storage stability of the solution.

  The resin composition according to the present embodiment preferably has a water content of 3,000 mass ppm or less. The water content of the resin composition is preferably 2500 mass ppm or less, preferably 2000 mass ppm or less, preferably 1500 mass ppm or less, and 1,000 mass ppm from the viewpoint of viscosity stability when storing the resin composition. More preferably, it is more preferably 500 ppm by mass or less, more preferably 300 ppm by mass or less, and preferably 100 ppm by mass or less.

The solution viscosity of the resin composition according to the present embodiment is preferably 500 to 200,000 mPa · s, more preferably 2,000 to 100,000 mPa · s, and 3,000 to 30,000 mPa · s at 25 ° C. Is particularly preferred. This solution viscosity can be measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., VISCONICEHD). When the solution viscosity is lower than 300 mPa · s, coating during film formation is difficult, and when it is higher than 200,000 mPa · s, there is a possibility that stirring during synthesis becomes difficult.
(A) When a polyimide precursor is synthesized, even if the solution becomes highly viscous, it is possible to obtain a resin composition having a good handleability by adding a solvent after the reaction and stirring. is there.

The resin composition of the present embodiment has the following characteristics in a preferred embodiment.
After the resin composition is applied to the surface of the support to form a coating film, the polyimide precursor is heated by heating at 430 ° C. for 1 hour in a nitrogen atmosphere (in nitrogen having an oxygen concentration of 2,000 ppm or less). In the polyimide film obtained by imidizing the body, the yellowness at a film thickness of 10 μm is preferably 20 or less. 18 or less is preferable, 16 or less is preferable, 14 or less is preferable, 13 or less is preferable, 10 or less is preferable, and 7 or less is preferable.

  Moreover, it is preferable that the residual stress of the polyimide film obtained in this way is 25 Mpa or less. The preferred residual stress is 23 MPa or less, 20 MPa or less, 18 MPa or less, and 16 MPa or less.

  Moreover, it is preferable that the glass transition temperature Tg of the polyimide film obtained in this way is 360 degreeC or more. A preferred glass transition temperature Tg is 470 ° C. or higher.

  Moreover, it is preferable that the retardation Rth in the 10-micrometer film thickness of the polyimide film obtained in this way is 1000 nm or less. Preferred retardation Rth is 800 nm or less, 700 nm or less, 500 nm or less, 300 nm or less, 200 nm or less, 140 nm or less, and 100 nm or less.

  Moreover, it is preferable that the tensile elongation in a 10 micrometer film thickness of the polyimide film obtained in this way is 15% or more. Preferred tensile elongation is 20% or more, 25% or more, 30% or more, 35% or more, and 40% or more.

The resin composition according to the present embodiment can be suitably used for forming a transparent substrate of a display device such as a liquid crystal display, an organic electroluminescence display, a field emission display, or electronic paper. Specifically, it can be used for forming a thin film transistor (TFT) substrate, a color filter substrate, a transparent conductive film (ITO, Indium Thin Oxide) substrate, and the like.
Since the resin precursor of this embodiment can form a polyimide film having a residual stress of 25 MPa or less, it can be easily applied to a display manufacturing process including a TFT element device on a colorless transparent polyimide substrate.

<Resin film>
Another aspect of the present invention provides a resin film formed from the aforementioned resin precursor.
Moreover, another aspect of this invention provides the method of manufacturing a resin film from the above-mentioned resin composition.
The resin film in the present embodiment is
Forming a coating film by applying the resin composition described above on the surface of the support (application process);
A step of heating the support and the coating film to imidize the polyimide precursor contained in the coating film to form a polyimide resin film (heating step);
A step of peeling the polyimide resin film from the support (peeling step);
It is characterized by including.

Here, the support is not particularly limited as long as it has heat resistance at the heating temperature in the subsequent step and has good peelability. For example, a glass (eg, alkali-free glass) substrate;
Silicon wafers;
Resin substrates such as PET (polyethylene terephthalate), OPP (stretched polypropylene), polyethylene glycol terephthalate, polyethylene glycol naphthalate, polycarbonate, polyimide, polyamideimide, polyetherimide, polyetheretherketone, polyethersulfone, polyphenylenesulfone, polyphenylenesulfide ;
A metal substrate such as stainless steel, alumina, copper, or nickel is used.

  In the case of forming a film-like polyimide molded body, for example, a glass substrate, a silicon wafer or the like is preferable. In the case of forming a film-like or sheet-like polyimide molded body, for example, PET (polyethylene terephthalate), OPP A support made of (stretched polypropylene) or the like is preferable.

Examples of coating methods include doctor blade knife coaters, air knife coaters, roll coaters, rotary coaters, flow coaters, die coaters, bar coaters, and other coating methods, spin coating, spray coating, dip coating and the like; screen printing and Printing techniques such as gravure printing can be applied.
The coating thickness should be appropriately adjusted according to the desired thickness of the resin film and the content of the polyimide precursor in the resin composition, but is preferably about 1 to 1,000 μm. The application step is sufficient at room temperature, but the resin composition may be heated in the range of 40 to 80 ° C. for the purpose of reducing viscosity and improving workability.

  Following the coating process, a drying process may be performed, or the drying process may be omitted and the process may proceed directly to the next heating process. This drying step is performed for the purpose of removing the organic solvent. When performing a drying process, suitable apparatuses, such as a hot plate, a box-type dryer, and a conveyor type dryer, can be utilized, for example. It is preferable to perform a drying process at 80-200 degreeC, and it is more preferable to carry out at 100-150 degreeC. The duration of the drying step is preferably 1 minute to 10 hours, and more preferably 3 minutes to 1 hour.

As described above, a coating film containing a polyimide precursor is formed on the support.
Subsequently, a heating process is performed. The heating step is a step of removing the organic solvent remaining in the coating film in the above drying process and advancing the imidization reaction of the polyimide precursor in the coating film to obtain a film made of polyimide.
This heating process can be performed using apparatuses, such as an inert gas oven, a hot plate, a box-type dryer, and a conveyor type dryer, for example. This step may be performed simultaneously with the drying step, or both steps may be performed sequentially.

The heating step may be performed in an air atmosphere, but it is recommended that the heating step be performed in an inert gas atmosphere from the viewpoints of safety, transparency of the obtained polyimide film, and YI value. Examples of the inert gas include nitrogen and argon.
Although heating temperature may be suitably set according to the kind of (b) organic solvent, 250 to 550 degreeC is preferable and 300 to 450 degreeC is more preferable. When it is 250 ° C. or higher, imidization is sufficient, and when it is 550 ° C. or lower, there are no inconveniences such as a decrease in transparency and deterioration of heat resistance of the obtained polyimide film. The heating time is preferably about 0.5 to 3 hours.
In the present embodiment, the oxygen concentration in the ambient atmosphere in the heating step is preferably 2,000 ppm by mass or less, more preferably 100 ppm by mass or less, from the viewpoint of the transparency and YI value of the obtained polyimide film. More preferred is mass ppm or less. By heating in an atmosphere having an oxygen concentration of 2,000 mass ppm or less, the YI value of the resulting polyimide film can be made 30 or less.

Depending on the intended use and purpose of the polyimide resin film, a peeling step for peeling the resin film from the support is required after the heating step. This peeling step is preferably performed after cooling the resin film on the support to room temperature to about 50 ° C.
Examples of the peeling step include the following aspects (1) to (4).

(1) After producing a structure including a polyimide resin film / support by the above method, a laser is irradiated from the support side of the structure to ablate the interface between the support and the polyimide resin film. , A method of peeling polyimide resin. Examples of the laser include a solid (YAG) laser and a gas (UV excimer) laser. It is preferable to use a spectrum with a wavelength of 308 nm or the like (refer to JP-T2007-512568, JP-T2012-511173, etc.).
(2) A method in which a release layer is formed on a support before applying the resin composition to the support, and then a polyimide resin film / release layer / a structure including the support is obtained to release the polyimide resin film. . Examples of the release layer include a method using parylene (registered trademark, manufactured by Japan Parylene Godo Kaisha), tungsten oxide; a method using a release agent such as vegetable oil, silicone, fluorine, alkyd, and the like (JP 2010). -67957, JP 2013-179306, etc.).
You may use together this method (2) and the laser irradiation of said (1).

(3) A method of obtaining a polyimide resin film by etching a metal with an etchant after obtaining a structure including a polyimide resin film / support using a metal substrate that can be etched as a support. As the metal, for example, copper (as an example, electrolytic copper foil “DFF” manufactured by Mitsui Mining & Smelting Co., Ltd.), aluminum, or the like can be used. As the etchant, ferric chloride or the like can be used for copper, and dilute hydrochloric acid or the like can be used for aluminum.
(4) After obtaining the structure including the polyimide resin film / support by the above method, an adhesive film is attached to the surface of the polyimide resin film to separate the adhesive film / polyimide resin film from the support, and then the adhesive film Of separating the polyimide resin film from the substrate.

Among these peeling methods, the method (1) or (2) is appropriate from the viewpoint of the refractive index difference between the front and back of the polyimide resin film to be obtained, the YI value, and the elongation. The method (1) is more appropriate from the viewpoint of the refractive index difference.
In addition, in the method (3), when using copper as a support body, the YI value of the polyimide resin film obtained becomes large, and the tendency for elongation to become small is seen. This is considered to be an influence of copper ions.

  Although the thickness of the resin film obtained by said method is not specifically limited, It is preferable that it is the range of 1-200 micrometers, More preferably, it is 5-100 micrometers.

The resin film according to the present embodiment may have a yellowness YI of 20 or less at a film thickness of 10 μm. Such characteristics include, for example, the immobilization of the resin precursor of the present disclosure in a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2,000 ppm or less), preferably 400 ° C. to 550 ° C., more preferably 400 ° C. to 450 ° C. By realizing, it is realized well.
The resin film according to the present embodiment can further have a tensile elongation of 15% or more. The tensile elongation of the resin film can be further 20% or more, particularly 30% or more. As a result, the resin film according to the present embodiment is excellent in breaking strength when handling a flexible substrate, and thus can improve the yield when manufacturing a flexible display. The tensile elongation can be measured using a commercially available tensile tester using a 10 μm-thick resin film as a sample.

<Laminate>
Another aspect of the present invention provides a laminate comprising a support and a polyimide resin film formed from the above resin composition on the surface of the support.
Still another embodiment of the present invention provides a method for producing the laminate.
The laminate in the present embodiment is a process of forming a coating film by applying the resin composition described above on the surface of the support (application process), and heating the support and the coating film. And a step (heating step) of forming a polyimide resin film by imidizing the polyimide precursor contained in the coating film.
The manufacturing method of said laminated body can be implemented like the manufacturing method of the above-mentioned resin film except not performing a peeling process, for example.

This laminated body can be used suitably for manufacture of a flexible device, for example.
This will be described in detail below.
When forming a flexible display, a glass substrate is used as a support, a flexible substrate is formed thereon, and a TFT or the like is further formed thereon. The step of forming a TFT or the like on a flexible substrate is typically performed at a wide temperature range of 150 to 650 ° C. However, when LTPS is formed as a TFT, an extremely high temperature is required as compared with amorphous silicon (250 ° C.) or IGZO (350 ° C.), and heating of about 400 ° C. to 550 ° C. is required.
On the other hand, due to these thermal histories, various physical properties (especially yellowness and elongation) of the polyimide film tend to be reduced. However, the polyimide film obtained from the polyimide precursor according to the present invention is extremely low in yellowness and elongation even in a high temperature region of 400 ° C. or higher, and can be used favorably in that region.
When the polyimide film of this embodiment is formed on LTPS, a better heat cycle test result can be obtained as compared with the case where the polyimide film is formed on IGZO. For this reason, the polyimide film of this embodiment is suitably used when the device type of TFT is LTPS.

当該積層体の製造方法としては前述の支持体と、該支持体の表面上に前述の樹脂組成物から形成されたポリイミド樹脂膜とを含む、積層体を製造した後に、アモルファスシリコン層を形成し、４００〜４５０℃で０．５〜３時間程度脱水素アニールを行った後に、エキシマレーザー等で結晶化することにより低温ポリシリコン層を形成することができる。
その後、レーザー剥離などでガラスとポリイミドフィルムを剥離することによって、上記積層体を得ることができる。
また、必要に応じてポリイミドフィルム上にＳｉＯ_２やＳｉＮなどの無機膜を形成した後に、ＬＴＰＳ層を形成することもできる。
前記ポリイミドフィルム層としては、ヘイズおよび伸度の観点から、下記一般式（６）であることがより好ましい。

Furthermore, in this Embodiment, the laminated body containing the polyimide film layer containing the polyimide represented by following General formula (5), and a LTPS layer can be provided.

As the method for producing the laminate, an amorphous silicon layer is formed after producing a laminate including the above-mentioned support and a polyimide resin film formed from the above-mentioned resin composition on the surface of the support. After performing dehydrogenation annealing at 400 to 450 ° C. for about 0.5 to 3 hours, a low temperature polysilicon layer can be formed by crystallization with an excimer laser or the like.
Then, the said laminated body can be obtained by peeling glass and a polyimide film by laser peeling etc.
Further, if necessary, an LTPS layer can be formed after forming an inorganic film such as SiO ₂ or SiN on the polyimide film.
The polyimide film layer is more preferably the following general formula (6) from the viewpoint of haze and elongation.

  At this time, if the residual stress generated in the glass substrate and the polyimide resin film is high, when the laminate composed of both expands in the high-temperature TFT forming process and contracts during cooling at room temperature, the glass substrate warps and breaks, and the flexible substrate Problems such as peeling from the glass substrate may occur. In general, since the thermal expansion coefficient of a glass substrate is smaller than that of a resin, a residual stress is generated between the glass substrate and the flexible substrate. Since the resin film concerning this embodiment can make the residual stress produced between glass substrates into 25 Mpa or less as mentioned above, it can be used conveniently for formation of a flexible display.

Furthermore, the polyimide film concerning this Embodiment can make yellowness YI in a 10 micrometer film thickness when a polyimide film is heated at 430 degree | times 20 or less, and can make tensile elongation 15% or more. . As a result, the resin film according to the present embodiment is excellent in breaking strength when handling a flexible substrate, and thus can improve the yield when manufacturing a flexible display.
Although the above embodiment is a description of an embodiment of manufacturing an LTPS-TFT substrate for a flexible display, an embodiment as a display device will be described below.
An example of the flexible display is an organic EL display.

  The organic EL display is a so-called flexible display whose display portion can be flexibly deformed (has flexibility). FIG. 1 is a diagram illustrating a part of the configuration of the organic EL structure unit 25. The organic EL structure part 25 is formed on the lower substrate 2a composed of the glass substrate 21, the photothermal exchange film 22, the transparent resin layer 23, and the base coat 24, and is composed of the same constituent members as those constituting a general organic EL display. For example, an organic EL element 250a that emits red light, an organic EL element 250b that emits green light, and an organic EL element 250c that emits blue light are arranged in a matrix as a unit, and a partition (bank) 251 Thus, the light emitting region of each organic EL element is defined. Each organic EL element includes a lower electrode (anode) 252, a hole transport layer 253, a light emitting layer 254, and an upper electrode (cathode) 255. In addition, a plurality of TFTs 256 (a-Si, p-Si, oxide semiconductor) for driving the organic EL elements are provided on the lower substrate 2a.

(Method for manufacturing organic EL display)
The manufacturing process of the organic EL display 20 includes an organic EL substrate manufacturing process, a sealing substrate manufacturing process, an assembling process for bonding both substrates, and a peeling process for peeling the glass substrates 21 and 29.
A well-known manufacturing process can be applied to the organic EL substrate manufacturing process, the sealing substrate manufacturing process, and the assembly process. One example is given below, but the present invention is not limited to this. Moreover, a peeling process is the same as the peeling process of the polyimide film mentioned above.

For example, first, an LTPS-TFT substrate for a flexible display is manufactured by the method described above, and then an interlayer insulating film having a contact hole is formed using a photosensitive acrylic resin or the like. An ITO film is formed by sputtering or the like, and a lower electrode is formed so as to make a pair with the TFT.
Next, after forming partition walls with photosensitive polyimide or the like, a hole transport layer and a light emitting layer are formed in each space partitioned by the partition walls. An upper electrode is formed so as to cover the light emitting layer and the partition. Through the above steps, an organic EL substrate is produced, and a top emission type flexible organic EL display is produced by sealing with a sealing film or the like. You may produce a bottom emission type flexible organic EL display by a well-known method.

In addition, after preparing the LTPS-TFT substrate, a color filter glass substrate provided with colorless and transparent polyimide is prepared, and a sealing material made of a thermosetting epoxy resin or the like is applied to one of the TFT substrate and the CF substrate by screen printing. It is applied to a frame-like pattern lacking the inlet portion, and a spherical spacer made of plastic or silica having a diameter corresponding to the thickness of the liquid crystal layer is sprayed on the other substrate.
Next, the TFT substrate and the CF substrate are bonded together, and the sealing material is cured.
Finally, after injecting a liquid crystal material into the space surrounded by the TFT substrate, the CF substrate and the sealing material by a decompression method, a thermosetting resin is applied to the liquid crystal injection port, and the liquid crystal material is sealed by heating to form a liquid crystal layer Form. 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 by a laser peeling method or the like.

Accordingly, another aspect of the present invention provides a display substrate.
Still another aspect of the present invention provides a method for manufacturing the display substrate.
The manufacturing method of the display substrate in the present embodiment is as follows:
Forming a coating film by applying the resin composition described above on the surface of the support (application process);
A step of heating the support and the coating film to imidize the polyimide precursor contained in the coating film to form a polyimide resin film (heating step);
A step of forming an element or a circuit on the polyimide resin film (element / circuit formation step);
A step (peeling step) of peeling the polyimide resin film on which the element or circuit is formed from the support.

In the above method, the coating step, the heating step, and the peeling step can be performed in the same manner as in the above-described resin film manufacturing method.
The element / circuit formation step can be performed by a method known to those skilled in the art.

  The resin film according to the present embodiment satisfying the above physical properties is suitably used for uses such as colorless transparent substrates for flexible displays, protective films for color filters, etc., where use is restricted by the yellow color of existing polyimide films. The Furthermore, for example, protective films, diffuser sheets and coating films for TFT-LCDs (for example, TFT-LCD interlayers, gate insulating films, liquid crystal alignment films, etc.), touch panel ITO substrates, smartphone cover glass substitute resin substrates It can also be used in fields where colorless transparency and low birefringence are required.

  Resin films and laminates produced using the polyimide precursor and resin precursor according to the present embodiment can be applied as, for example, semiconductor insulating films, TFT-LCD insulating films, electrode protective films, etc. In production, it can be suitably used particularly as a substrate. Here, examples of the flexible device to which the resin film and the laminate according to this embodiment can be applied include a flexible display, a flexible solar cell, a flexible touch panel electrode substrate, flexible lighting, and a flexible battery.

EXAMPLES Hereinafter, although this invention is further explained in full detail based on an Example, these are described for description and the range of this invention is not limited to the following Example.
Various evaluations in Examples and Comparative Examples were performed as follows.

<Measurement of weight average molecular weight>
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) under the following conditions.
As a solvent, NMP (manufactured by Wako Pure Chemical Industries, Ltd., for high performance liquid chromatograph, 24.8 mmol / L lithium bromide monohydrate (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.5%) and 63 immediately before measurement are used. .2 mmol / L phosphoric acid (dissolved by adding Wako Pure Chemical Industries, Ltd., for high performance liquid chromatograph) was used. A calibration curve for calculating the weight average molecular weight was prepared using standard polystyrene (manufactured by Tosoh Corporation).

Column: Shodex KD-806M (manufactured by Showa Denko KK)
Flow rate: 1.0 mL / min Column temperature: 40 ° C
Pump: PU-2080 Plus (manufactured by JASCO)
Detector: RI-2031Plus (RI: differential refractometer, manufactured by JASCO) and UV-2075Plus (UV-VIS: UV-visible absorptiometer, manufactured by JASCO)

<Evaluation of content of low molecular weight molecules (low molecular weight content)>
The content of molecules having a molecular weight of less than 1,000 in the resin is determined by the ratio (percentage) of the peak area occupied by the component having a molecular weight of less than 1,000 to the peak area of the entire molecular weight distribution, using the GPC measurement results obtained above. ).

<Evaluation of water content>
The moisture content of the synthetic solvent and the resin composition (varnish) was measured using a Karl Fischer moisture measuring device (a trace moisture measuring device AQ-300, manufactured by Hiranuma Sangyo Co., Ltd.).

<Evaluation of viscosity stability of resin composition>
For the resin compositions prepared in each of the Examples and Comparative Examples, viscosity measurement at 23 ° C. was performed using a sample that was allowed to stand at room temperature for 3 days after preparation as a sample after preparation;
Thereafter, the sample was further allowed to stand at room temperature for 2 weeks, and the viscosity at 23 ° C. was measured again as a sample after 2 weeks. These viscosity measurements were performed using a temperature controller viscometer (TV-22 manufactured by Toki Sangyo Co., Ltd.).
Using the above measured values, the viscosity change rate at room temperature for 2 weeks was calculated according to the following formula.
Viscosity change rate (%) at room temperature for 2 weeks = [(viscosity of sample after 2 weeks) − (viscosity of sample after preparation)] / (viscosity of sample after preparation) × 100
The viscosity change rate at room temperature for 2 weeks was evaluated according to the following criteria.
A: Viscosity change rate is 5% or less (storage stability “excellent”)
○: Viscosity change rate is more than 5 and 10% or less (storage stability “good”)
×: Viscosity change rate exceeds 10% (storage stability “bad”)

<Evaluation of varnish applicability>
The resin composition prepared in each of the examples and comparative examples was applied on a non-alkali glass substrate (size 37 × 47 mm, thickness 0.7 mm) using a bar coater so that the film thickness after curing was 15 μm. Thereafter, prebaking was performed at 140 ° C. for 60 minutes.
The applicability of the varnish was evaluated by measuring the step on the coating film surface using a step gauge (manufactured by Tencor, model name P-15).
A: Surface level difference is 0.1 μm or less (applicability “excellent”)
○: Surface level difference is more than 0.1 and less than 0.5 um (applicability “good”)
×: Surface level difference exceeds 0.5 μm (applicability “bad”)

<Evaluation of residual stress>
Each resin composition was applied by a spin coater onto a 6-inch silicon wafer having a thickness of 625 μm ± 25 μm, for which the “warping amount” had been measured in advance, and prebaked at 100 ° C. for 7 minutes. Then, using a vertical curing furnace (manufactured by Koyo Lindberg, model name: VF-2000B), the oxygen concentration in the chamber is adjusted to 10 ppm by mass or less, and heat curing treatment at 430 ° C. for 1 hour ( A silicon wafer with a polyimide resin film having a thickness of 10 μm after curing was prepared.
The amount of warpage of the wafer was measured using a residual stress measuring device (manufactured by Tencor, model name FLX-2320), and the residual stress generated between the silicon wafer and the resin film was evaluated.

<Evaluation of yellowness (YI value)>
The resin composition prepared in each of the examples and comparative examples was spin-coated on a 6-inch silicon wafer substrate provided with an aluminum vapor deposition layer on the surface so that the film thickness after curing was 10 μm, and then at 100 ° C. for 7 minutes. Pre-baked. Then, using a vertical curing furnace (manufactured by Koyo Lindberg, model name VF-2000B), the oxygen concentration in the cabinet is adjusted to 10 mass ppm or less, and a heat curing treatment at 430 ° C. for 1 hour is performed. And a wafer having a polyimide resin film formed thereon was produced.
The laminate wafer obtained above was immersed in a dilute hydrochloric acid aqueous solution, and the polyimide film was peeled off from the wafer to obtain a polyimide film sample having an inorganic film formed on the surface.
About the obtained polyimide resin film, YI value (film thickness conversion of 10 micrometers) was measured by Nippon Denshoku Industries Co., Ltd. (Spectrophotometer: SE600) using D65 light source.

<Evaluation of elongation and breaking strength>
A wafer was prepared in the same manner as in the above <Evaluation of Yellowness>. Using a dicing saw (DAD 3350, manufactured by DISCO Corporation), a 3 mm wide cut was made in the polyimide resin film of the wafer, and then immersed in a dilute hydrochloric acid solution overnight to peel off the resin film piece and dried. This was cut into a length of 50 mm to obtain a sample.
About said sample, elongation and breaking strength were measured using TENSILON (Orientec UTM-II-20) at a test speed of 40 mm / min and an initial load of 0.5 fs.

[Synthesis Example 1]
To a 3 L separable flask equipped with a stir bar equipped with an oil bath, NMP1 (1065 g) was added while introducing nitrogen gas, and 4,4′-diaminodiphenylsulfone (248.3 g) as a diamine was added with stirring. Then, PMDA (218.12 g) was added as acid dianhydride and stirred at room temperature for 30 minutes. This was heated to 50 ° C. and stirred for 12 hours, and then the oil bath was removed and the temperature was returned to room temperature to obtain a transparent polyamic acid NMP solution (hereinafter also referred to as varnish) (varnish P-1). The composition here and the weight average molecular weight (Mw) of the resulting polyamic acid are shown in Table 1, respectively. Table 2 shows the test results of the film cured at 430 ° C.

[Example 1]
To a 3 L separable flask equipped with a stir bar equipped with an oil bath, NMP2 (1065 g) was added while introducing nitrogen gas, and 4,4′-diaminodiphenylsulfone (248.3 g) as a diamine was added with stirring, followed by PMDA (218.12 g) was added as an acid dianhydride and stirred at room temperature for 30 minutes. This was heated to 80 ° C. and stirred for 3 hours, and then the oil bath was removed and the temperature was returned to room temperature to obtain a transparent polyamic acid NMP solution (hereinafter also referred to as varnish) (varnish P-2). The composition here and the weight average molecular weight (Mw) of the resulting polyamic acid are shown in Table 1, respectively. Table 2 shows the test results of the film cured at 430 ° C.

[Example 2]
Synthesis was performed in the same manner as in Example 1 except that NMP2 was changed to NMP3 (varnish P-3). The results are shown in Tables 1 and 2.

[Example 3]
In the amine, except that 4,4′-diaminodiphenyl sulfone as the first diamine and amine-modified methylphenyl silicone oil at both ends as the second diamine were added in a molar ratio of 99.33: 0.67 Was synthesized in the same manner as in Example 2 (varnish P-4). The results are shown in Tables 1 and 2.

[Examples 4 to 13]
Synthesis was performed in the same manner as in Example 3 except that the types and molar ratios of the first diamine and the second diamine were changed as shown in Table 1 (varnishes P-5 to P-14). The results are shown in Tables 1 and 2.

[Example 14]
In acid dianhydride, pyromellitic dianhydride was added as the first acid dianhydride and biphenyltetracarboxylic dianhydride was added as the second acid dianhydride in a molar ratio of 80:20. Except for the above, synthesis was performed in the same manner as in Example 2 (varnish P-15). The results are shown in Tables 1 and 2.

[Examples 15 to 17]
The acid dianhydride was synthesized in the same manner as in Example 2 except that the molar ratio of the first acid dianhydride and the second acid dianhydride was changed as shown in Table 1 (Varnish P-16). ~ P-18). The results are shown in Tables 1 and 2.

[Example 18]
Synthesis was performed in the same manner as in Example 2 except that 4,4′-diaminodiphenylsulfone was changed to 3,3′-diaminodiphenylsulfone in diamine (varnish P-19).

[Comparative Examples 1 to 6]
Synthesis was performed in the same manner as in Example 2 except that the acid dianhydride and diamine were changed as shown in Table 1 (varnish P-20 to varnish P-25).

  Table 1 shows the compositions of the above Examples and Comparative Examples and the weight average molecular weight (Mw) of the obtained polyamic acid. Table 2 shows the test results of the film cured at 430 ° C.

表中における各成分の略称は、それぞれ、以下の意味である。
ＰＭＤＡ：ピロメリット酸二無水物
ＢＰＤＡ：ビフェニルテトラカルボン酸二無水物
４，４’−ＤＡＳ：４，４’−ジアミノジフェニルスルホン
３，３’−ＤＡＳ：３，３’−ジアミノジフェニルスルホン
ＡＰＡＢ：４−アミノフェニル−４−アミノベンゾエート
ｐ−ＰＤ：p-フェニレンジアミン
６ＦＤＡ：４，４’−（ヘキサフルオロイソプロピリデン）ジフタル酸無水物
ＣＨＤＡ：１，４−シクロヘキサンジアミン
ＤＳＤＡ：３，３’、４，４’−ジフェニルスルホンテトラカルボン酸二無水物
ＨＰＭＤＡ ：１，２，４，５−シクロヘキサンテトラカルボン酸二無水物
ＴＦＭＢ：２，２’−ビス（トリフルオロメチル）ベンジジン
Ｘ−２２−１６６０Ｂ−３：両末端アミン変性メチルフェニルシリコーンオイル（信越化学社製）
ＮＭＰ１：５００ｍｌビン入り品を開封後一か月放置したもの、水分量３，０７０ｐｐｍ
ＮＭＰ２：５００ｍｌビン入り品を開封後一週間放置したもの、水分量１５００ｐｐｍ
ＮＭＰ３：１８Ｌ缶開封直後のもの、水分量２５０ｐｐｍ

Abbreviations of each component in the table have the following meanings.
PMDA: pyromellitic dianhydride BPDA: biphenyltetracarboxylic dianhydride 4,4′-DAS: 4,4′-diaminodiphenyl sulfone 3,3′-DAS: 3,3′-diaminodiphenyl sulfone APAB: 4 -Aminophenyl-4-aminobenzoate p-PD: p-phenylenediamine 6FDA: 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride CHDA: 1,4-cyclohexanediamine DSDA: 3, 3', 4, 4′-diphenylsulfonetetracarboxylic dianhydride HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride TFMB: 2,2′-bis (trifluoromethyl) benzidine X-22-1660B-3: Both-end amine-modified methylphenyl silicone oil (Shin-Etsu Chemical Co., Ltd.)
NMP1: 500ml bottled product left for one month after opening, moisture content 3,070ppm
NMP2: 500ml bottled product left for a week after opening, water content 1500ppm
NMP3: Immediately after opening the 18L can, water content 250ppm

As is clear from Table 1 and Table 2, the resin compositions of Synthesis Example 1 and Examples 1 to 18 having the structure represented by the general formula (1) are compared with the resin compositions of Comparative Examples 1 to 6. It can be seen that the residual stress is small, the yellowness is low, and the elongation is high.
In particular, in Examples 1 to 18, in which the weight average molecular weight of the polyimide precursor is 40,000 or more and 300,000 or less and the content of molecules having a weight average molecular weight of less than 1,000 is less than 5% by mass, The elongation is higher than that, and particularly good results are obtained. Specifically, a resin film having a residual stress of 25 MPa or less, a yellowness YI of 20 or less, and an elongation of 15% or more can be obtained.
Further, comparing Synthesis Example 1 and Examples 1 and 2, it can be seen that the smaller the water content of the solvent used in the polymerization reaction, the smaller the content of molecules having a molecular weight of less than 1,000.

[Synthesis Examples, Examples 1 to 18, Comparative Examples 1 to 6]
An organic EL substrate as shown in FIG. 1 was produced.
After applying the polyimide precursor varnishes of Synthesis Example 1 and Examples and Comparative Examples on a mother glass substrate (thickness 0.7 mm) to a post-cure film thickness of 10 μm using a bar coater, at 140 ° C. Pre-baked for 60 minutes. Subsequently, using a vertical curing furnace (manufactured by Koyo Lindberg Co., Ltd., model name VF-2000B), the oxygen concentration in the chamber was adjusted to 10 mass ppm or less, and a heat curing treatment at 430 ° C. for 1 hour was performed. And a glass substrate on which a polyimide resin film was formed.
Subsequently, a SiN layer was formed to a thickness of 100 nm by a CVD (Chemical Vapor Deposition) method.
Subsequently, a titanium film was formed by a sputtering method, and then patterning was performed by a photolithography method to form a scanning signal line.
Next, a SiN layer having a thickness of 100 nm was formed on the entire glass substrate on which the scanning signal lines were formed by a CVD method. (This is the lower substrate 2a.)
Subsequently, an amorphous silicon layer 256 was formed on the lower substrate 2a, dehydrogenation annealing was performed at 430 ° C. for 1 hour, and then an excimer laser was irradiated to form an LTPS layer.

Thereafter, a photosensitive acrylic resin was coated on the entire surface of the lower substrate 2a by spin coating, and exposure and development were performed by photolithography to form an interlayer insulating film 258 having a plurality of contact holes 257. Through this contact hole 257, a part of each LTPS 256 was exposed.
Next, an ITO film is formed on the entire surface of the lower substrate 2a on which the interlayer insulating film 258 is formed by a sputtering method, exposed and developed by a photolithography method, patterned by an etching method, and paired with each LTPS. Thus, the lower electrode 259 was formed.
In each contact hole 257, the lower electrode 252 penetrating the interlayer insulating film 258 and the LTPS 256 were electrically connected.
Next, after forming the partition 251, the hole transport layer 253 and the light emitting layer 254 were formed in each space partitioned by the partition 251. In addition, an upper electrode 255 was formed so as to cover the light emitting layer 254 and the partition 251. An organic EL substrate was produced by the above process.

Next, a UV curable resin is coated around the sealing substrate 2b on which the glass substrate, the polyimide film of the present embodiment, and the SiN layer are formed in this order, and the sealing substrate 2b and the organic EL substrate are bonded in an argon gas atmosphere. By adhering, the organic EL element was enclosed. Thereby, the hollow part 261 was formed between each organic EL element and the sealing substrate 2b.
Excimer laser (wavelength: 308 nm, repetition frequency: 300 Hz) was irradiated from the lower substrate 2a side and the sealing substrate 2b side of the laminate thus formed, and peeling was performed with the minimum energy necessary for peeling the entire surface. .

About this laminated body, the presence or absence of the board | substrate curvature after peeling, a lighting test, and the cloudiness evaluation of a laminated body was evaluated. A heat cycle test was also conducted. The results are shown in Table 3.
<Board warpage>
◎: No warpage ○: Little warpage △: Curled by warpage <Lighting test>
○: Lighted up ×: Lighted off <Laminated body cloudiness evaluation>
After forming a laminated body, it observed visually, the thing which the whole device was transparent was set to (circle), what was slightly cloudy was set to (triangle | delta), and what became cloudy was made x.
<Heat cycle test>
Using an ESPEC heat cycle tester, the appearance was observed after 1000 cycles of −5 ° C. and 60 ° C. for 30 minutes each (moving time of the tank of 1 minute).
The case where no peeling or swelling was observed was indicated by “◯”, the case where peeling or swelling was partially observed after the test was indicated by Δ, and the case where peeling or swelling was observed entirely after the test was indicated by ×.

  As is apparent from Table 3, in Examples 1 to 18 using varnishes P-2 to P-19, there is no warpage of the substrate, the lighting test is good, there is no cloudiness, and the heat cycle characteristics are good. A laminate can be obtained. Such a laminate can be suitably used as a low-temperature polysilicon TFT element substrate, for example, a transparent flexible substrate of an organic EL display.

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

  By using the polyimide precursor and resin composition of the present invention, a resin film having a residual stress of 25 MPa or less, a yellowness YI of 20 or less, and an elongation of 15% or more can be obtained. Such a resin film can be applied to, for example, a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, and the like, and can be suitably used as a substrate particularly in the manufacture of flexible displays and touch panel ITO electrode substrates. it can.

2a Lower substrate 2b Sealing substrate 250a Organic EL element that emits red light 250b Organic EL element that emits green light 250c Organic EL element that emits blue light 251 Partition (bank)
252 Lower electrode (anode)
253 Hole transport layer 254 Light emitting layer 255 Upper electrode (cathode)
256 LTPS
257 Contact hole 258 Interlayer insulating film 259 Lower electrode 261 Hollow part

Claims (34)

A resin composition for a substrate of a low-temperature polysilicon TFT element, comprising a polyimide precursor obtained by polymerizing a diamine component and an acid dianhydride component, and a solvent,
The polyimide precursor is
(A) The following general formula (1):

The resin composition for the board | substrates of the low-temperature polysilicon TFT element characterized by including the structure shown by these. The polyimide precursor has the following general formula (2):

The resin composition for the substrate of the low-temperature polysilicon TFT element according to claim 1, comprising a structure represented by:   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 1 or 2, wherein the polyimide precursor has a weight average molecular weight of 40,000 or more and 300,000 or less.   The total amount of solids contained in the resin composition is 100% by mass, and the amount of molecules having a molecular weight of less than 1,000 contained in the solids is less than 5% by mass. 4. A resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of 1 to 3.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 4, wherein the amount of the molecule having a molecular weight of less than 1,000 contained in the solid content is 1% by mass or less. When the polyimide precursor has a total mass of the diamine component and the acid dianhydride component of 100% by mass,
Following formula (3):

(In the formula, a plurality of R ₃ and R ₄ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200.)
The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of claims 1 to 5, wherein the content of the silicone diamine component having a structure represented by the formula is less than 6% by mass.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 6, wherein the content of the silicone diamine component is 5.9% by mass or less.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 7, wherein the content of the silicone diamine component is 3% by mass or less. When the total number of moles of the diamine component is 100 mol%, the polyimide precursor is contained in the polyimide precursor and has the following general formula (4):

(Wherein R ₁ , R ₂ and R ₃ each independently represents a monovalent organic group having 1 to 20 carbon atoms, n represents 0 or 1, and a, b and c are integers of 0 to 4) .)
The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of claims 1 to 8, wherein the amount of diamine represented by the formula is 48 mol% or less.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 9, wherein the amount of the diamine represented by the general formula (4) contained in the polyimide precursor is less than 1 mol%.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 10, wherein the amount of the diamine represented by the general formula (4) contained in the polyimide precursor is 0.9 mol% or less.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 9, wherein the polyimide precursor contains 4-aminophenyl-4-aminobenzoate as a diamine component represented by the general formula (4). .   The polyimide precursor according to any one of claims 1 to 12, wherein the content of the 4-aminophenyl-4-aminobenzoate is 48 mol% or less when the total number of moles of the diamine component is 100 mol%. A resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 1.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 13, wherein the polyimide precursor has a content of the 4-aminophenyl-4-aminobenzoate of less than 1 mol%.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 14, wherein the content of the 4-aminophenyl-4-aminobenzoate is less than 0.9 mol% in the polyimide precursor.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of claims 1 to 15, wherein the polyimide precursor contains diaminodiphenyl sulfone as the diamine component.   The substrate of the low-temperature polysilicon TFT element according to claim 16, wherein the polyimide precursor has a content of the diaminodiphenyl sulfone of 90 mol% or more when the total number of moles of the diamine component is 100 mol%. Resin composition.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of claims 1 to 17, wherein the polyimide precursor contains pyromellitic dianhydride as the acid dianhydride component.   The low temperature according to claim 18, wherein the polyimide precursor has a pyromellitic dianhydride content of 90 mol% or more when the total number of moles of the acid dianhydride component is 100 mol%. A resin composition for a substrate of a polysilicon TFT element.   20. The low-temperature polysilicon TFT element according to claim 1, wherein the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour has a yellowness of 20 or less at a film thickness of 10 μm. Resin composition for substrate.   21. The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 20, wherein the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour has a yellowness of 13 or less at a film thickness of 10 μm.   The glass transition temperature of a polyimide film obtained by heating the resin composition at 430 ° C for 1 hour is 360 ° C or higher, and the substrate for a low-temperature polysilicon TFT element according to any one of claims 1 to 21 Resin composition.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 22, wherein a glass transition temperature of a polyimide film obtained by heating the resin composition at 430 ° C for 1 hour is 470 ° C or higher.   The substrate of the low-temperature polysilicon TFT element according to any one of claims 1 to 23, wherein a retardation of a polyimide film obtained by heating the resin composition at 430 ° C for 1 hour is 1000 nm or less at a film thickness of 10 µm. Resin composition.   The resin composition for a substrate of a low-temperature polysilicon TFT element according to claim 24, wherein a retardation of a polyimide film obtained by heating the resin composition at 430 ° C for 1 hour is 140 nm or less at a film thickness of 10 µm. Applying the resin composition according to any one of claims 1 to 25 on the surface of the support;
Forming a polyimide resin film from the resin composition;
Peeling the polyimide resin film from the support;
A method for producing a resin film, comprising:   The manufacturing method of the resin film of Claim 26 which performs the process of irradiating a laser from the said support body side prior to the process of peeling the said polyimide resin film from the said support body.   A method for producing a display, comprising a method for producing a resin film by the method according to claim 26 or 27. Applying the resin composition according to any one of claims 1 to 25 on the surface of the support;
Forming a polyimide resin film from the resin composition;
Forming a low-temperature polysilicon TFT on the polyimide resin film;
The manufacturing method of the laminated body containing this.   The manufacturing method of the laminated body of Claim 29 which further includes the process of peeling the said polyimide resin film from the said support body.   The manufacturing method of a flexible device containing the manufacturing method of the laminated body of Claim 29 or 30. The following general formula (5):

The laminated body characterized by including the polyimide layer containing the polyimide represented by these, and a low-temperature polysilicon TFT layer.   The laminate according to claim 32, wherein the amount of molecules having a molecular weight of less than 1,000 contained in the polyimide layer is less than 5% by mass.   A polyimide film having a yellowness of 20 or less, a residual stress of 25 MPa or less, and an elongation of 15% or more when heated at 430 ° C. at a film thickness of 10 μm.

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