JP7038630B2 - Polyimide precursor, resin composition, resin film and its manufacturing method - Google Patents

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.

Generally, a polyimide resin film is used as a resin film for applications requiring high heat resistance. In a general polyimide resin, a polyimide precursor is produced by solution-polymerizing an aromatic carboxylic acid dianhydride and an aromatic diamine, and then the polyimide precursor is thermally imidized at a high temperature or chemically imidized using a catalyst. It is a highly heat-resistant resin that is manufactured by converting it into a heat-resistant resin.

The polyimide resin is an insoluble and infusible super heat resistant resin, and has excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low temperature resistance, and chemical resistance. Therefore, polyimide resins are used in a wide range of fields including electronic materials. Examples of applications of polyimide resins in the field of electronic materials include insulating coating agents, insulating films, semiconductor protective films, TFT-LCD electrode protective films, and the like. Recently, instead of the glass substrate conventionally used in the field of display materials, adoption as a colorless transparent flexible substrate utilizing its lightness and flexibility is being considered.

When producing a polyimide resin film as a flexible substrate, a composition containing a polyimide precursor is applied onto an appropriate support to form a coating film, and then heat treatment is performed to imidize the polyimide resin. Get the film. As the support, for example, glass, silicon, silicon nitride, silicon oxide, metal and the like are used. When producing a laminate having a polyimide film on such a support, heat treatment at a high temperature of 250 ° C. or higher is required for drying and imidization of the polyimide precursor. This heat treatment causes residual stress in the laminate, which causes serious problems such as warpage and peeling. This is because the linear thermal expansion coefficient of polyimide is larger than that of the material constituting the support.

As a polyimide material having a small coefficient of thermal expansion, a polyimide formed from 3,3', 4,4'-biphenyltetracarboxylic dianhydride and para-phenylenediamine is best known. It has been reported that this polyimide film exhibits a very low coefficient of linear thermal expansion, although it depends on the film thickness and production conditions (Non-Patent Document 1).
Further, it has been reported that polyimide having an ester structure in a molecular chain exhibits a low coefficient of linear thermal expansion because it has appropriate linearity and rigidity (Patent Document 1).

However, since general polyimide resins including the polyimides described in the above documents are colored brown or yellow due to a high aromatic ring density, the light transmittance in the visible light region is low, and therefore colorless transparency is required. It is difficult to use it in various fields. 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. It is high and inadequate in terms of colorless transparency.
Regarding the yellowness of the film, for example, it is known that polyimide using a monomer having a fluorine atom exhibits an extremely low yellowness (Patent Document 2).
Further, a polyimide precursor having both 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 ed. 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 (retalysis) is low.
Conventionally, since the device type of the TFT manufactured for driving the display display is amorphous silicon or IGZO, the process temperature is 350 ° C. or lower.
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 exhibiting the above physical properties even after such high temperature thermal history is desired. It is rare.

However, the known physical characteristics of transparent polyimide are not sufficient for use as a heat-resistant colorless transparent substrate for a display.
Further, as confirmed by the present inventor, although the polyimide resin described in Patent Document 1 showed a low coefficient of linear thermal expansion, the degree of yellowness (YI value) of the polyimide resin film after peeling was large, and in addition, It was found that there is a problem that the residual stress is high.
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 remarkably after a high-temperature heat history of 400 ° C. or higher. I found out that I would do it.

The present invention has been made in view of the problems described above. Therefore, in the present invention, the yellowness (YI value) after high temperature thermal history is small, the residual stress with the glass substrate is small, the glass transition temperature is high, and the Rth is preferably used when the device type of the TFT is LTPS. It is an object of the present invention to provide a polyimide resin film having a low retardation, a method for producing the same, and a laminate.

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 present inventors have conducted extensive research to solve the above problems. As a result, it was found that the polyimide resin film obtained by curing the resin composition containing the 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. It was also found that the polyimide film having a specific structure and the laminate containing the LTPS layer did not warp when used as an organic EL device, the lighting test was good, and the amount of ash after laser peeling was small. Based on these findings. This has led to the present invention.
That is, the present invention is as follows.
[1]
A resin composition for a substrate of a low-temperature polysilicon TFT element, which comprises 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):

A resin composition for a substrate of a low temperature polysilicon TFT element, comprising the structure shown by.
[2]
The polyimide precursor has the following general formula (2):

The resin composition for a substrate of the low temperature polysilicon TFT element according to [1], which comprises the structure shown 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 or more and 300,000 or less.
[4]
When the total weight of the solid content 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 solid content is less than 5% by mass [1]. ] To [3]. The resin composition for the substrate of the low temperature polysilicon TFT element 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 molecules having a molecular weight of less than 1,000 contained in the solid content is 1% by mass or less.
[6]
The polyimide precursor has a total mass of the diamine component and the acid dianhydride component of 100% by mass.
The following formula (3):

(In the formula, R3 and R4 existing in a plurality are independently monovalent organic groups 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 including the structure represented by (1) 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]
The polyimide precursor is contained in the polyimide precursor when the total number of moles of the diamine component is 100 mol%.

(In the formula, R ₁ , R ₂ , and R ₃ each independently represent 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. Is.)
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 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 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 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]
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% [1] to [12]. The resin composition for the substrate of the low temperature polysilicon TFT element according to any one of.
[14]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [13], wherein the polyimide precursor has a content of 4-aminophenyl-4-aminobenzoate of less than 1 mol%.
[15]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [14], wherein the polyimide precursor has a content of 4-aminophenyl-4-aminobenzoate of less than 0.9 mol%.
[16]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of [1] to [15], wherein the polyimide precursor contains diaminodiphenyl sulfone as the diamine component.
[17]
The substrate of the low-temperature polysilicon TFT element according to [16], wherein the polyimide precursor has a content of 90 mol% or more of the diaminodiphenyl sulfone when the total number of moles of the diamine component is 100 mol%. Resin composition for.
[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 acid dianhydride as the acid dianhydride component.
[19]
The low temperature according to [18], wherein the polyimide precursor has a content of pyromellitic dianhydride 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 any one of [1] to [19], wherein the yellowness of the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour is 20 or less at a film thickness of 10 μm. Resin composition for substrates.
[21]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [20], wherein the yellowness of the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour is 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 the glass transition temperature of the polyimide film obtained by heating the resin composition at 430 ° C. for 1 hour is 470 ° C. or higher.
[24]
The substrate for 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 for.
[25]
The resin composition for a substrate of a low-temperature polysilicon TFT element according to [24], wherein the retardation of the 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]
The step of applying the resin composition according to any one of [1] to [25] on the surface of the support, and
A step of forming a polyimide resin film from the resin composition and
The step of peeling the polyimide resin film from the support and
A method for producing a resin film, which comprises.
[27]
The method for producing a resin film according to claim 26, wherein a step of irradiating a laser from the support side is performed prior to the step of peeling the polyimide resin film from the support.
[28]
A method for manufacturing a display, which comprises a method for manufacturing a resin film by the method according to claim [26] or [27].
[29]
The step of applying the resin composition according to any one of [1] to [25] on the surface of the support, and
A step of forming a polyimide resin film from the resin composition and
The step of forming a low-temperature polysilicon TFT on the polyimide resin film and
A method for manufacturing a laminate including.
[30]
The method for producing a laminate according to [29], further comprising a step of peeling the polyimide resin film from the support.
[31]
A method for manufacturing a flexible device, which comprises the method for manufacturing a laminate according to [29] or [30].
[32]
The following general formula (5):

A laminate comprising a polyimide layer containing a polyimide represented by (1) 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 at a film thickness of 10 μm when heated at 430 ° C.

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 a substrate, a high glass transition temperature, and a low Rth (retalysis).
Further, the laminate containing the polyimide film and the low-temperature polysilicon TFT obtained from the resin composition according to the present invention has less warpage, low haze, and good heat cycle test results.

The figure which shows the organic EL structure which applied this invention to the organic EL substrate.

Hereinafter, embodiments of the present invention (hereinafter, abbreviated as “embodiments”) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof. Further, unless otherwise specified, the characteristic values described in the present disclosure are values measured by the 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 aspect 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 this embodiment is
(A) The following general formula (1):

It is a polyimide precursor shown by.
As the acid dianhydride used in the general formula (1) according to the present embodiment, pyromellitic acid dianhydride (hereinafter, also referred to as PMDA) can be exemplified.
Examples of the diamine used in the general formula (1) according to the present embodiment include 4,4'-diaminodiphenyl sulfone and 3,3'-diaminodiphenyl sulfone.
Among them, 4,4'-diaminodiphenyl sulfone represented by the following general formula (2) is used from the viewpoint of residual stress, YI, glass transition temperature, retardation Rth, elongation, and haze of the obtained polyimide film. It is more preferable that the structure is the same.

The weight average molecular weight (Mw) of the polyimide precursor in this embodiment is preferably 10,000 to 300,000, and particularly preferably 40,000 to 300,000. When the weight average molecular weight is 40,000 or more, the mechanical properties such as elongation and breaking strength are particularly excellent, the residual stress is low, and the YI is low. When the weight average molecular weight is smaller than 300,000, it becomes easy to control the weight average molecular weight at the time of synthesizing the polyamic acid, a resin composition having an appropriate viscosity can be obtained, and the coatability of the resin composition is improved. In the present disclosure, the weight average molecular weight is a value 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 smaller. 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. It is preferably 0.5% by mass or less, preferably 0.1% by mass or less, preferably 0.05% by mass or less, and preferably 0.02% by mass or less.

Such a composition is excellent in viscosity stability and varnish coating property. Further, the polyimide film obtained from such a composition is preferable because it has a low residual stress, a small YI, a high glass transition temperature (Tg), a low retardation Rth, and a high elongation. Further, the laminate containing such a polyimide film and the low-temperature polysilicon TFT has less 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 the peak area obtained by GPC measurement of the resin composition.

As the polyimide precursor in the present embodiment, other acid dianhydrides can be used in addition to pyromellitic acid 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-franyl) -3-methyl-cyclohexene-1,2 Dicarboxylic acid anhydride, 1,2,3,4-benzenetetracarboxylic acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 2,2', 3,3'-benzophenone Tetracarboxylic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 3,3', 4,4'-diphenylsulfone tetracarboxylic acid dianhydride, 2,2', 3 , 3'-biphenyltetracarboxylic acid dianhydride, methylene-4,4'-diphthalic acid dianhydride, 1,1-ethylidene-4,4'-diphthalic acid dianhydride, 2,2-propylidene-4, 4'-Diphthalic acid dianhydride, 1,2-ethylene-4,4'-diphthalic acid dianhydride, 1,3-trimethylethylene-4,4'-diphthalic acid dianhydride, 1,4-tetramethylene- 4,4'-Diphthalic acid dianhydride, 1,5-pentamethylene-4,4'-diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, p-phenylenebis (trimeritate acid anhydride) , Thio-4,4'-diphthalic acid dianhydride, sulfonyl-4,4'-diphthalic acid dianhydride, 1,3-bis (3,4-dicarboxyphenyl) benzene dianhydride, 1,3- Bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,3-bis [2- (3,4-dicarboxyphenyl) )-2-propyl] benzene dianhydride, 1,4-bis [2- (3,4-dicarboxyphenyl) -2-propyl] benzene dianhydride, bis [3- (3,4-dicarboxyphenoxy) ) Phenyl] methane dianhydride, bis [4- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, 2,2-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 acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic Acid dianhydride, 1,2,5,6-naphthalente Tracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic An acid dianhydride or the like can be exemplified.

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

The polyimide precursor in the present embodiment includes 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and the like, as long as the elongation, strength, stress, yellowness, etc. 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-aminophenoxy) 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- (4- (4-aminophenyl) 4-Aminophenoxy) phenyl) propane, 2,2-bis [4- (4-aminophenoxy) phenyl) hexafluoropropane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, etc. can be mentioned. , It is preferable to use one or more selected from these.

The content of the 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 the total diamine 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 diaminodiphenyl sulfone, the better in terms 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 of the polyimide precursor 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.

(In the formula, R ₁ , R ₂ , and R ₃ each independently represent 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. Is.)

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

In particular, the polyimide precursor contains 4-aminophenyl-4-amino as the diamine component represented by the general formula (4) when the total number of moles of the diamine component is 100 mol%. The content of benzoate is preferably 48 mol% or less. The effects of small YI, high Tg, low retardation, and high elongation can be obtained. 4-Aminophenyl-4-aminobenzoate may or may not be contained.
The smaller the amount of 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 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,
The following formula (3):

(A plurality of R ₃ and R ₄ existing in the formula are independently monovalent organic groups having 1 to 20 carbon atoms, and h is an integer of 3 to 200.)
The content of the silicone diamine component including the structure represented by is preferably less than 6% by mass.

The smaller the silicone diamine component containing the structure represented by the above formula (3), the smaller the YI, the larger the glass transition temperature Tg, and the smaller the retardation Rth, which is preferable. The content of the silicone diamine component containing the structure represented by the above formula (3) is preferably 5.9% by mass or less, 5.5% by mass or less, 5.0% by mass or less, and 4. 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% by mass or less, 0.2% by mass or less, 0.1% by mass or less, 0.08% by mass or less, 0.06% by mass or less, 0.04 It is not more than mass% and 0.02% by mass or less.

The polyimide precursor in the embodiment may be a polyamide-imide precursor by using a dicarboxylic acid in addition to the above-mentioned tetracarboxylic acid dianhydride as long as the performance is not impaired. By using such a precursor, various performances such as improvement of mechanical elongation, improvement of glass transition temperature, reduction of yellowness and the like can be adjusted in the obtained film. Examples of such a dicarboxylic acid include a dicarboxylic acid having an aromatic ring and an alicyclic dicarboxylic acid. 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 carbon atoms here also includes the number of carbon atoms contained in the carboxyl group.
Of these, a dicarboxylic acid having an aromatic ring is preferable.

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'-sulfonylbis benzoic acid, 3,4'-sulfonylbis benzoic acid, 3,3'-sulfonylbis benzoic acid , 4,4'-oxybis benzoic acid, 3,4'-oxybis benzoic acid, 3,3'-oxybis benzoic 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'-biphenyldicarboxylic acid, 2,2'-dimethyl-3,3'-biphenyldicarboxylic acid 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-carboxy) Phenoxy) -m-terphenyl, 3,4'-bis (4-carboxyphenoxy) -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-ter Phenyl, 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'-benzophenonedicarboxylic acid, 1,3-phenylene diacetic acid, 1,4-phenylene diacetic acid, etc .; and 5-aminoisophthal as described in WO 2005/068535. 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 or an active ester derived from thionyl chloride or the like.

[Manufacturing of polyimide precursor]
The polyimide precursor (polyamic acid) of the present invention contains pyromellitic acid dianhydride and a diamine (for example, 4,4'-diaminodiphenyl sulfone) used for the structural unit represented by the above general formula (1). , Can be synthesized by polycondensation reaction. This reaction is preferably carried out in a suitable solvent. Specific examples thereof include a method in which a predetermined amount of 4,4'-DAS is dissolved in a solvent, a predetermined amount of pyromellitic acid dianhydride is added to the obtained diamine solution, and the mixture is stirred.

The ratio (molar ratio) of the tetracarboxylic acid dianhydride component to the diamine component when synthesizing the polyimide precursor is the heat ray expansion rate, residual stress, elongation, and yellowness (hereinafter, YI) of the obtained resin film. From the viewpoint of controlling (also referred to as) to a desired range, tetracarboxylic acid dianhydride: diamine = 100: 90 to 100: 110 (diamine 0.90 to 1. per 1 mol part of tetracarboxylic acid dianhydride. The range is preferably in the range of 10 mol parts), and more preferably in the range of 100: 95 to 100: 105 (0.95 to 1.05 mol parts of diamine with respect to 1 mol part of acid dianhydride).
In the present 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 an end sealant. It is possible. The closer the ratio of the acid dianhydride component to the diamine component is to 1: 1 and the smaller the amount of the end-capping agent used, the larger the molecular weight of the polyamic acid can be.
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 further preferably 99.5% by mass or more. When a plurality of types of acid dianhydride components or diamine components are used in combination, it is sufficient that the acid dianhydride components or diamine components have the above-mentioned purity as a whole, but all types of acid dianhydride components to be used. It is preferable that the component and the diamine component each have the above-mentioned 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 can dissolve the tetracarboxylic dianhydride component and the diamine component and the generated polyamic acid and can obtain a high molecular weight polymer. Specific examples of such a solvent include an aprotic solvent, a phenol-based solvent, an ether and a glycol-based solvent, and the like. Specific examples of these include, as the aprotic solvent, for example, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N-methyl. Caprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, the following general formula (7):

In the formula, R ₁₂ = Equamid M100 represented by a methyl group (trade name: manufactured by Idemitsu Kosan Co., Ltd.), R ₁₂ = Equamid B100 represented by an n-butyl group (trade name: manufactured by Idemitsu Kosan Co., Ltd.), etc. Amide solvent;
Lactone-based solvents such as γ-butyrolactone and γ-valerolactone;
Phosphorus-containing amide-based solvents such as hexamethylphosphoric amide and hexamethylphosphine triamide;
Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane;
Ketone solvents such as cyclohexanone and methylcyclohexanone;
Tertiary amine solvents such as picoline and pyridine;
Ester solvents such as acetic acid (2-methoxy-1-methyl ethyl):
As the phenol-based solvent, for example, phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2, 5-Xylenole, 2,6-Xylenol, 3,4-Xylenole, 3,5-Xylenole, etc .:
Examples of the ether and glycol-based solvent 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.

The boiling point of the solvent used for synthesizing the polyamic acid at normal pressure is preferably 60 to 300 ° C, more preferably 140 to 280 ° C, and particularly preferably 170 to 270 ° C. If the boiling point of the solvent is higher than 300 ° C., a drying step is required for a long time. On the other hand, if the boiling point of the solvent is lower than 60 ° C., roughening may occur on the surface of the resin film, air bubbles may be mixed into the resin film, and the like, 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., and more preferably a vapor pressure of 250 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 mass ppm or less.
These solvents may be used alone or in combination of two or more.

In the resin composition of the present embodiment, the content of molecules having a molecular weight of less than 1,000 is preferably less than 5% by mass.
It is considered that the reason why the molecule having a molecular weight of less than 1,000 is present in the resin composition is that the water content of the solvent and the raw material (acid dianhydride, diamine) used at the time of synthesis is involved. That is, it is considered that the acid anhydride group of some acid anhydride monomers is hydrolyzed by water to become a carboxyl group and remains in a low molecular weight state without increasing the 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 preferably 3000 mass ppm or less, and more preferably 1000 mass ppm or less.

The water content of the solvent is the grade of the solvent used (dehydration grade, general-purpose grade, etc.), solvent container (bin, 18L can, canister can, etc.), storage state of the solvent (presence or absence of rare gas filling, etc.), from opening to use. It is considered that the time (whether it is used immediately after opening or after a lapse of time after opening, etc.) is involved. In addition, it is considered that the substitution of rare gas in the reactor before synthesis, the presence or absence of noble gas flow during synthesis, etc. are also involved. Therefore, (a) when synthesizing the polyimide precursor, a high-purity product is used as a raw material, a solvent having a low water content is used, and measures are taken to prevent water from the environment from being mixed into the system before and during the reaction. Is recommended.

When dissolving each monomer component in a solvent, it may be heated if necessary.
(A) The reaction temperature at the time of synthesizing the polyimide precursor is preferably 0 ° C to 120 ° C, more preferably 40 ° C to 100 ° C, and further preferably 60 to 100 ° C. By carrying out the polymerization reaction at this temperature, a polyimide precursor having a high degree of polymerization can be obtained. The polymerization time is preferably 1 to 100 hours, more preferably 2 to 10 hours. When the polymerization time is 1 hour or more, a polyimide precursor having a uniform degree of polymerization can be obtained, and when the polymerization time is 100 hours or less, a polyimide precursor having a high degree of polymerization can be obtained.

The polyimide precursor according to the present embodiment may contain other polyimide precursors, if necessary, as long as the desired performance of the present invention is not impaired.
As such a polyimide precursor, for example, a polyimide precursor obtained by polycondensing the above-mentioned other acid dianhydride and another diamine can be exemplified.
The mass ratio of the other polyimide precursors according to the present embodiment is preferably 30% by mass or less, preferably 10% by mass or less, based on the total amount of (a) polyimide precursors, as well as the YI value. It is more preferable from the viewpoint of reducing the oxygen dependence of the light transmittance.

In a preferred embodiment of the present embodiment, (a) the polyimide precursor may be partially imidized. In this case, the imidization ratio is preferably 80% or less, more preferably 50% or less. This partial imidization is obtained by heating the above-mentioned (a) polyimide precursor to dehydrate and ring closure. This heating is preferably carried out at a temperature of preferably 120 to 200 ° C., more preferably 150 to 180 ° C., preferably 15 minutes to 20 hours, and more preferably 30 minutes to 10 hours.
Further, N, N-dimethylformamide dimethylacetal or N, N-dimethylformamide diethylacetal is added to the polyamic acid obtained by the above reaction and heated to esterify a part or all of the carboxylic acid. By using it as the (a) polyimide precursor in the present embodiment, it is possible to obtain a resin composition having improved viscosity stability when stored at room temperature. In addition to these ester-modified polyamic acids, the above-mentioned acid dianhydride component is sequentially reacted with 1 equivalent of a monovalent alcohol with respect to the acid anhydride group and a dehydration condensing agent such as thionyl chloride and dicyclohexylcarbodiimide. After that, it can also be obtained by a method of conducting a condensation reaction with a diamine component.

The proportion of the (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, and 10 to 10 to 40% by mass from the viewpoint of coating film forming property. 30% by mass is particularly preferable.

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。

The second aspect of the present embodiment is represented by the following general formula (1), in which the weight average molecular weight is 40,000 or more and 300,000 or less, and the content of the molecule having a weight average molecular weight of less than 1000 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 the molecule 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 should be kept below a specific range, the purity of the raw material should be increased, and the molar ratio of the acid dianhydride to the diamine should be within the specific range. Can be achieved by.
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.
The range of tetracarboxylic dianhydride: diamine = 100: 90 to 100: 110 (0.90 to 1.10 mol of diamine per 1 mol of tetracarboxylic dianhydride) is preferable. It is more preferably in the range of 95 to 100: 105 (0.95 to 1.05 mol of diamine per 1 mol of acid dianhydride).
The polyimide precursor preferably has a structure represented by the following general formula (2) from the viewpoint of haze and elongation of the obtained polyimide film.

If the polyimide precursor has only the 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. It is not possible to provide a polyimide film satisfying 15% or more. In the present 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 1000 is 5% by mass. By using a polyimide precursor having a molecular weight of less than or equal to less than, it is possible to provide a polyimide film further satisfying the elongation. Specifically, it is possible to provide 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 at a film thickness of 10 microns after heating at 430 ° C. ..

<Resin composition>
Another aspect of the present invention provides a resin composition containing (a) a polyimide precursor and (b) an organic solvent described above. 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 above-mentioned (a) polyimide precursor and other components arbitrarily used. As such (b) the organic solvent, the above-mentioned solvent can be used as the solvent that can be used in the synthesis of (a) the polyimide precursor. The preferred organic solvent is 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 the (a) polyimide precursor.
The amount of the organic solvent (b) is preferably such that the solid content concentration of the resin composition is 3 to 50% by mass. Further, it is preferable to add the resin composition after adjusting the composition and amount of (b) the organic solvent so that the viscosity (25 ° C.) of the resin composition is 500 mPa · s to 100,000 mPa · s.

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

((C) Surfactant)
By adding a surfactant to the resin composition of the present embodiment, the coatability of the resin composition can be improved. Specifically, it is possible to prevent the occurrence of streaks in the coating film.
Examples of such a surfactant include silicone-based surfactants, fluorine-based surfactants, and nonionic surfactants other than these. Examples of these include, as silicone-based surfactants, for example, organosiloxane polymers KF-640, 642, 643, KP341, X-70-092, X-70-093, (hereinafter, trade name, Shin-Etsu Chemical Co., Ltd.). , SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (above, 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 (trade name, manufactured by Nippon Unicar Co., Ltd.), DBE-814, DBE-224, DBE- 621, CMS-626, CMS-222, KF-352A, KF-354L, KF-355A, KF-6020, DBE-821, DBE-712 (Gelest), BYK-307, BYK-310, BYK-378, BYK -333 (trade name, manufactured by Big Chemie Japan), Granol (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), etc.;
Examples of the fluorine-based surfactant include Megafuck F171, F173, R-08 (manufactured by Dainippon Ink and Chemicals, Inc., trade name), Florard FC4430, FC4432 (Sumitomo 3M Ltd., trade name) and the like;
Examples of the nonionic surfactant other than these include polyoxyethylene uralyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether and the like, respectively.

Among these surfactants, silicone-based surfactants and fluorine-based surfactants are preferable from the viewpoint of coatability (streak suppression) of the resin composition, and the YI value and total light transmittance depending on the oxygen concentration during the curing step are preferable. From the viewpoint of the influence on the rate, a silicone-based surfactant is preferable.
(C) When a surfactant is used, the blending amount thereof is preferably 0.001 to 5 parts by mass, preferably 0.01 to 3 parts by mass with respect to 100 parts by mass of the (a) polyimide precursor in the resin composition. 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 the manufacturing process of a flexible device or the like, the resin composition. The product can contain 0.01 to 20% by mass of the alkoxysilane compound with respect to 100% by mass of the (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. Further, it is preferable that the content of the alkoxysilane compound is 20% by mass or less from the viewpoint of storage stability of the resin composition. The content of the alkoxysilane compound is more preferably 0.02 to 15% by mass, further preferably 0.05 to 10% by mass, and 0.1 to 0.1 to 100 parts by mass with respect to 100 parts by mass of the polyimide precursor. It is particularly preferably 8% by mass.
By using an alkoxysilane compound as an additive for the resin composition according to the present embodiment, in addition to the above-mentioned improvement in adhesion, the coatability (suppression of swelling) of the resin composition is further improved and obtained. It is possible to reduce the dependence of the YI value of the cured film on the oxygen concentration during curing.

Examples of the alkoxysilane compound include 3-ureidopropyltriethoxysilane, bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 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, diethoxydiphenyl Examples thereof include silane, dimethoxydi-p-tolylsilane, triphenylsilanol, and an alkoxysilane compound represented by each of the following structures, and it is preferable to use one or more selected from these.

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 a resin composition. Further, if necessary, in the temperature range of room temperature (25 ° C.) to 80 ° C., (b) one or more of the organic solvent and other components are added to the polyimide precursor, and the mixture is stirred and mixed, and then the resin composition is formed. It may be used 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 / revolution mixer, or the like can be used. Further, heat of 40 to 100 ° C. may be applied as needed.

On the other hand, when (a) the solvent used when synthesizing the polyimide precursor and (b) the organic solvent are different, the solvent in the synthesized polyimide precursor solution is used, for example, reprecipitation, solvent distillation, etc. After removing (a) the polyimide precursor by an appropriate method, (b) an organic solvent and, if necessary, other components are added in a temperature range of room temperature to 80 ° C., and the mixture is stirred and mixed. May prepare a resin composition.

After preparing the resin composition as described above, the composition solution is heated at, for example, 130 to 200 ° C. for, for example, 5 minutes to 2 hours to dehydrate a part of the polyimide precursor to the extent that the polymer does not precipitate. 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 range of the imidization 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 this 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 or less, from the viewpoint of viscosity stability when the resin composition is stored. It is more preferably less than or equal to, more preferably 500 mass ppm or less, preferably 300 mass ppm or less, and preferably 100 mass ppm 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 preferable. This solution viscosity can be measured using an E-type viscometer (VISCONICE HD manufactured by Toki Sangyo Co., Ltd.). If the solution viscosity is lower than 300 mPa · s, it may be difficult to apply the film when forming the film, and if it is higher than 200,000 mPa · s, it may be difficult to stir during the synthesis.
(A) Even if the solution becomes highly viscous when synthesizing the polyimide precursor, it is possible to obtain a resin composition having a viscosity that is easy to handle by adding a solvent and stirring after the reaction is completed. be.

The resin composition of the present embodiment has the following properties in a preferred embodiment.
After applying the resin composition to the surface of the support to form a coating film, the polyimide precursor is heated at 430 ° C. for 1 hour under 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. The yellowness at a film thickness of 10 μm is preferably 18 or less, preferably 16 or less, preferably 14 or less, preferably 13 or less, preferably 10 or less, and preferably 7 or less.

Further, the residual stress of the polyimide film thus obtained is preferably 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.

Further, the glass transition temperature Tg of the polyimide film thus obtained is preferably 360 ° C. or higher. The preferable glass transition temperature Tg is 470 ° C. or higher.

Further, it is preferable that the retardation Rth of the polyimide film thus obtained at a film thickness of 10 μm 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.

Further, it is preferable that the tensile elongation of the polyimide film thus obtained at a film thickness of 10 μm is 15% or more. Preferred tensile elongations are 20% or higher, 25% or higher, 30% or higher, 35% or higher, and 40% or higher.

The resin composition according to this 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 to form a thin film transistor (TFT) substrate, a color filter substrate, a transparent conductive film (ITO, IndiumThinOxide) substrate, and the like.
Since the resin precursor of the present embodiment can form a polyimide film having a residual stress of 25 MPa or less, it is easy to apply to a display manufacturing process in which a TFT element device is provided on a colorless transparent polyimide substrate.

<Resin film>
Another aspect of the present invention provides a resin film formed from the resin precursor described above.
Yet another aspect of the present invention provides a method for producing a resin film from the above-mentioned resin composition.
The resin film in this embodiment is
A step of forming a coating film by applying the above-mentioned resin composition on the surface of the support (coating step), and
A step (heating step) of imidizing the polyimide precursor contained in the coating film to form a polyimide resin film by heating the support and the coating film.
A step of peeling the polyimide resin film from the support (peeling step) and
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 steps and has good peelability. For example, a glass (eg, non-alkali glass) substrate;
Silicon wafer;
Resin substrates such as PET (polyethylene terephthalate), OPP (stretched polypropylene), polyethylene glycol terephthalate, polyethylene glycol naphthalate, polycarbonate, polyimide, polyamideimide, polyetherimide, polyether ether ketone, polyether sulfone, polyphenylene sulfone, polyphenylene sulfide, etc. ;
Metal substrates such as stainless steel, alumina, copper, and nickel are used.

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

Examples of the coating method include a doctor blade knife coater, an air knife coater, a roll coater, a rotary coater, a flow coater, a die coater, a bar coater and the like, a spin coat, a spray coat, a dip coat 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. Although the coating step may be carried out at room temperature, the resin composition may be heated in the range of 40 to 80 ° C. for the purpose of lowering the viscosity and improving workability.

The drying step may be performed following the coating step, or the drying step may be omitted and the process may proceed directly to the next heating step. This drying step is performed for the purpose of removing the organic solvent. When performing the drying step, for example, an appropriate device such as a hot plate, a box-type dryer, or a conveyor-type dryer can be used. The drying step is preferably performed at 80 to 200 ° C, more preferably 100 to 150 ° C. The implementation time of the drying step is preferably 1 minute to 10 hours, more preferably 3 minutes to 1 hour.

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

The heating step may be performed in an air atmosphere, but it is recommended to perform the heating step in an inert gas atmosphere from the viewpoint of safety, transparency of the obtained polyimide film and YI value. Examples of the inert gas include nitrogen, argon and the like.
The heating temperature may be appropriately set according to (b) the type of the organic solvent, but is preferably 250 ° C to 550 ° C, more preferably 300 to 450 ° C. If the temperature is 250 ° C. or higher, imidization is sufficient, and if the temperature is 550 ° C. or lower, there are no inconveniences such as deterioration of transparency and heat resistance of the obtained polyimide film. The heating time is preferably about 0.5 to 3 hours.
In the present embodiment, the oxygen concentration in the ambient atmosphere in the heating step is preferably 2,000 mass ppm or less, more preferably 100 mass ppm or less, from the viewpoint of transparency and YI value of the obtained polyimide film. More preferably, the mass is ppm or less. By heating in an atmosphere having an oxygen concentration of 2,000 mass ppm or less, the YI value of the obtained polyimide film can be reduced to 30 or less.

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

(1) By 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. , How to peel off the polyimide resin. Examples of the laser include a solid (YAG) laser, a gas (UV excimer) laser, and the like. It is preferable to use a spectrum having a wavelength of 308 nm or the like (see Japanese Patent Publication No. 2007-512568, Japanese Patent Publication No. 2012-511173, etc.).
(2) A method in which a release layer is formed on a support before the resin composition is applied to the support, and then a structure including a polyimide resin film / release layer / support is obtained and the polyimide resin film is peeled off. .. Examples of the release layer include a method using parylene (registered trademark, manufactured by Japan Parylene GK), a method using tungsten oxide; a method using a release agent such as a vegetable oil type, a silicone type, a fluorine type, and an alkyd type (Japanese Patent Laid-Open No. 2010). -67957, Japanese Patent Application Laid-Open No. 2013-179306, etc.).
This method (2) may be used in combination with the laser irradiation of the above (1).

(3) A method of obtaining a polyimide resin film by using an etchable metal substrate as a support, obtaining a structure including a polyimide resin film / support, and then etching the metal with an etchant. As the metal, for example, copper (specifically, electrolytic copper foil "DFF" manufactured by Mitsui Mining & Smelting Co., Ltd.), aluminum and 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 a structure including a 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. A method of separating a polyimide resin film from.

Among these peeling methods, the method (1) or (2) is appropriate from the viewpoint of the difference in refractive index between the front and back surfaces of the obtained polyimide resin film, the YI value, and the elongation, and the method (1) or (2) is suitable for the front and back surfaces of the obtained polyimide resin film. The method (1) is more appropriate from the viewpoint of the difference in refractive index.
When copper is used as the support in the method (3), the YI value of the obtained polyimide resin film tends to be large and the elongation tends to be small. This is considered to be the effect of copper ions.

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

The resin film according to this embodiment can have a yellowness YI of 20 or less at a film thickness of 10 μm. Such properties are, for example, an imide 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. It is well realized by making it.
Further, the resin film according to the present embodiment can 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 has excellent breaking strength when handling a flexible substrate, and therefore, it is possible to improve the yield when manufacturing a flexible display. This tensile elongation can be measured using a commercially available tensile tester using a resin film having a film thickness of 10 μm as a sample.

<Laminated body>
Another aspect of the present invention provides a laminate comprising a support and a polyimide resin film formed from the resin composition described above on the surface of the support.
Yet another aspect of the present invention provides a method for producing the above-mentioned laminate.
The laminate in the present embodiment is formed by a step of forming a coating film by applying the above-mentioned resin composition on the surface of the support (coating step) and by heating the support and the coating film. It can be obtained by a method for producing a laminated body, which comprises a step (heating step) of imidizing the polyimide precursor contained in the coating film to form a polyimide resin film.
The above-mentioned method for producing a laminated body can be carried out in the same manner as the above-mentioned method for producing a resin film, except that, for example, the peeling step is not performed.

This laminate can be suitably used, for example, in the manufacture of flexible devices.
More specifically, it is as follows.
When forming a flexible display, a glass substrate is used as a support, a flexible substrate is formed on the glass substrate, and a TFT or the like is further formed on the flexible substrate. The step of forming the TFT or the like on the flexible substrate is typically carried out at a temperature in a wide range of 150 to 650 ° C. However, when forming LTPS as a TFT, an extremely high temperature is required as compared with amorphous silicon (250 ° C.) and 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 (particularly yellowness and elongation) of the polyimide film tend to decrease, and when the temperature exceeds 400 ° C., the yellowness and elongation particularly decrease. However, the polyimide film obtained from the polyimide precursor according to the present invention has very little decrease in yellowness and elongation even in a high temperature region of 400 ° C. or higher, and can be used satisfactorily in the region.
When the polyimide film of the present embodiment is formed on LTPS, better heat cycle test results can be obtained than when it is formed on IGZO. Therefore, the polyimide film of the present embodiment is preferably used when the device type of the 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。

Further, in the present embodiment, it is possible to provide a laminate containing a polyimide film layer containing a polyimide represented by the following general formula (5) and an LTPS layer.

As a method for producing the laminate, an amorphous silicon layer is formed after the laminate is produced, which comprises the above-mentioned support and a polyimide resin film formed from the above-mentioned resin composition on the surface of the support. A low-temperature polysilicon layer can be formed by performing dehydrogenation annealing at 400 to 450 ° C. for about 0.5 to 3 hours and then crystallizing with an excimer laser or the like.
Then, the laminated body can be obtained by peeling the glass and the polyimide film by laser peeling or the like.
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 preferably has the following general formula (6) from the viewpoint of haze and elongation.

At this time, if the residual stress generated between the glass substrate and the polyimide resin film is high, the laminated body composed of both expands in the high-temperature TFT forming step and then shrinks when cooled at room temperature, resulting in warpage and breakage of the glass substrate, and a flexible substrate. Problems such as peeling from the glass substrate may occur. Generally, since the coefficient of thermal expansion of a glass substrate is smaller than that of a resin, residual stress is generated between the glass substrate and the flexible substrate. As described above, the resin film according to this embodiment can be suitably used for forming a flexible display because the residual stress generated between the resin film and the glass substrate can be 25 MPa or less.

Further, the polyimide film according to the present embodiment can have a yellowness YI of 20 or less and a tensile elongation of 15% or more at a film thickness of 10 μm when the polyimide film is heated at 430 degrees. .. As a result, the resin film according to the present embodiment has excellent breaking strength when handling a flexible substrate, and therefore, it is possible to improve the yield when manufacturing a flexible display.
The above aspect describes the embodiment of the production of the LTPS-TFT substrate for a flexible display, but the embodiment as a display device will be described below.
Examples of the flexible display include an organic EL display.

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

(Manufacturing method of 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 assembly step of bonding both substrates, and a peeling step of peeling the glass substrates 21 and 29.
A well-known manufacturing process can be applied to the organic EL substrate manufacturing process, the sealed substrate manufacturing process, and the assembling process. The following is an example, but the present invention is not limited to this. Further, the peeling step is the same as the peeling step of the polyimide film described above.

For example, first, the LTPS-TFT substrate for a flexible display is manufactured by the above-mentioned method, and then an interlayer insulating film having contact holes is formed with a photosensitive acrylic resin or the like. An ITO film is formed by a sputtering method or the like, and a lower electrode is formed so as to form a pair with the TFT.
Next, after forming a partition wall with photosensitive polyimide or the like, a hole transport layer and a light emitting layer are formed in each space partitioned by the partition wall. In addition, an upper electrode is formed so as to cover the light emitting layer and the partition wall. By the above steps, an organic EL substrate is manufactured, and by sealing with a sealing film or the like, a top emission type flexible organic EL display is manufactured. A bottom emission type flexible organic EL display may be manufactured by a known method.

Further, after manufacturing the above-mentioned LTPS-TFT substrate, a color filter glass substrate provided with colorless transparent polyimide is manufactured, and a liquid crystal display made of a heat-curable 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-shaped pattern lacking the inlet portion, and a spherical spacer having a diameter corresponding to the thickness of the liquid crystal layer and made of plastic or silica is sprayed on the other substrate.
Next, the TFT substrate and the CF substrate are bonded together to cure the sealing material.
Finally, after injecting the liquid crystal material into the space surrounded by the TFT substrate, CF substrate and sealing material by the 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. To 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.

Therefore, another aspect of the invention provides a display board.
Yet another aspect of the present invention provides a method of manufacturing the display substrate.
The method for manufacturing a display board in the present embodiment is as follows.
A step of forming a coating film by applying the above-mentioned resin composition on the surface of the support (coating step), and
A step (heating step) of imidizing the polyimide precursor contained in the coating film to form a polyimide resin film by heating the support and the coating film.
A step of forming an element or a circuit on the polyimide resin film (element / circuit forming step) and
It is characterized by including 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 each be performed in the same manner as the above-mentioned resin film manufacturing method.
The element / circuit forming step can be carried out by a method known to those skilled in the art.

The resin film according to the present embodiment satisfying the above physical characteristics is suitably used for applications whose use is restricted due to the yellow color of the existing polyimide film, particularly applications such as a colorless transparent substrate for a flexible display and a protective film for a color filter. To. Further, for example, a protective film, a diffuser sheet and a coating film in a TFT-LCD, etc. (for example, an interlayer of a TFT-LCD, a gate insulating film, a liquid crystal alignment film, etc.), an ITO substrate for a touch panel, a cover glass substitute resin substrate for a smartphone, etc. It can also be used in fields such as, where colorless transparency and low double-reflecting are required.

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

Hereinafter, the present invention will be described in more detail based on Examples, but these are described for the sake of explanation, and the scope of the present invention is not limited to the following Examples.
Various evaluations in Examples and Comparative Examples were performed as follows.

<Measurement of weight average molecular weight>
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 solvents, NMP (Wako Pure Chemical Industries, Ltd., for high-speed liquid chromatograph, 24.8 mmol / L lithium bromide monohydrate (Wako Pure Chemical Industries, Ltd., purity 99.5%) immediately before measurement) and 63. .2 mmol / L phosphoric acid (manufactured by Wako Pure Chemical Industries, Ltd., for high-speed liquid chromatograph) was added and dissolved) was used. The 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 velocity: 1.0 mL / min Column temperature: 40 ° C
Pump: PU-2080Plus (manufactured by JASCO)
Detector: RI-2031Plus (RI: differential refractometer, manufactured by JASCO) and UV-2075Plus (UV-VIS: ultraviolet-visible absorptiometer, manufactured by JASCO)

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

<Evaluation of water content>
The water content of the synthetic solvent and the resin composition (varnish) was measured using a Karl Fischer water content measuring device (trace water content 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, the viscosity of the prepared sample was measured at 23 ° C. by allowing the sample to stand at room temperature for 3 days after the preparation.
After that, the sample left at room temperature for 2 weeks was used as the sample after 2 weeks, and the viscosity was measured again at 23 ° C. These viscosity measurements were performed using a viscometer with a temperature controller (TV-22 manufactured by Toki Sangyo Kikai Co., Ltd.).
Using the above measured values, the rate of change in viscosity for 2 weeks at room temperature was calculated by the following formula.
Room temperature 2 weeks Viscosity change rate (%) = [(Viscosity of sample after 2 weeks)-(Viscosity of sample after preparation)] / (Viscosity of sample after preparation) x 100
The rate of change in viscosity for 2 weeks at room temperature was evaluated according to the following criteria.
⊚: Viscosity change rate is 5% or less (storage stability "excellent")
◯: Viscosity change rate is more than 5 and 10% or less (storage stability is “good”)
X: Viscosity change rate exceeds 10% (storage stability "poor")

<Evaluation of varnish applicability>
The resin compositions prepared in each of the examples and comparative examples were applied onto a non-alkali glass substrate (size 37 × 47 mm, thickness 0.7 mm) using a bar coater so as to have a film thickness of 15 μm after curing. Then, it was prebaked at 140 ° C. for 60 minutes.
The applicability of the varnish was evaluated by measuring the step on the surface of the coating film using a step meter (manufactured by Tencor, model name P-15).
⊚: Surface level difference is 0.1 um or less (applicability "excellent")
◯: The level difference on the surface is more than 0.1 and 0.5 um or less (applicability is “good”)
X: The level difference on the surface exceeds 0.5 um (applicability "poor")

<Evaluation of residual stress>
Each resin composition was applied by a spin coater on a 6-inch silicon wafer having a thickness of 625 μm ± 25 μm for which the “warp amount” had been measured in advance, and prebaked at 100 ° C. for 7 minutes. After that, using a vertical curing furnace (manufactured by Koyo Lindbergh Co., Ltd., model name VF-2000B), the oxygen concentration in the refrigerator was adjusted to 10% by mass or less, and heat curing treatment was performed at 430 ° C. for 1 hour. After curing, a silicon wafer with a polyimide resin film having a thickness of 10 μm was produced.
The amount of warpage of this wafer was measured using a residual stress measuring device (manufactured by Tencor Co., Ltd., 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 compositions prepared in each of the examples and comparative examples were spin-coated on a 6-inch silicon wafer substrate having an aluminum-deposited layer on the surface so that the film thickness after curing was 10 μm, and the temperature was 100 ° C. for 7 minutes. Pre-baked. After that, using a vertical curing furnace (manufactured by Koyo Lindbergh Co., Ltd., model name VF-2000B), the oxygen concentration in the refrigerator was adjusted to 10% by mass or less, and heat hardening treatment was performed at 430 ° C. for 1 hour. A wafer on which a polyimide resin film was formed was produced.
The laminate wafer obtained above was immersed in a dilute aqueous hydrochloric acid solution, and the polyimide film was peeled off from the wafer to obtain a sample of a polyimide film having an inorganic film formed on its surface.
The YI value (converted to a film thickness of 10 μm) of the obtained polyimide resin film was measured using a D65 light source manufactured by Nippon Denshoku Kogyo Co., Ltd. (Spectrophotometer: SE600).

<Evaluation of elongation and breaking strength>
A wafer was produced in the same manner as in the above <evaluation of yellowness>. After making a 3 mm wide cut in the polyimide resin film of the wafer using a dicing saw (DAD 3350 manufactured by DISCO Corporation), the wafer was immersed overnight in a dilute aqueous hydrochloric acid solution to peel off the resin film pieces and dried. This was cut to a length of 50 mm and used as a sample.
For the above sample, elongation and breaking strength were measured using TENSILON (UTM-II-20 manufactured by Orientech) at a test speed of 40 mm / min and an initial load of 0.5 fs.

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

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

[Example 2]
The synthesis was carried out 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, 4,4'-diaminodiphenyl sulfone as the first diamine and both-terminal amine-modified methylphenyl silicone oil as the second diamine were added so as to have a molar ratio of 99.33: 0.67. Was synthesized in the same manner as in Example 2 (Wanis P-4). The results are shown in Tables 1 and 2.

[Examples 4 to 13]
In the amine, the synthesis was carried out 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 the acid dianhydride, pyromellitic acid dianhydride as the first acid dianhydride and biphenyltetracarboxylic acid dianhydride as the second acid dianhydride were added so as to have a molar ratio of 80:20. Except for this, synthesis was carried out in the same manner as in Example 2 (Wanis P-15). The results are shown in Tables 1 and 2.

[Examples 15 to 17]
In the acid dianhydride, the synthesis was carried out in the same manner as in Example 2 except that the molar ratios of the first acid dianhydride and the second acid dianhydride were changed as shown in Table 1 (varnish P-16). ~ P-18). The results are shown in Tables 1 and 2.

[Example 18]
In the diamine, synthesis was carried out in the same manner as in Example 2 except that 4,4'-diaminodiphenyl sulfone was changed to 3,3'-diaminodiphenyl sulfone (varnish P-19).

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

Table 1 shows the compositions of each 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

The abbreviations for each component in the table have the following meanings.
PMDA: pyromellitic acid dianhydride BPDA: biphenyltetracarboxylic acid 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'-(hexafluoroisopropyridene) diphthalic acid anhydride CHDA: 1,4-cyclohexanediamine DSDA: 3,3', 4, 4'-Diphenyl sulfone tetracarboxylic acid dianhydride HPMDA: 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride TFMB: 2,2'-bis (trifluoromethyl) benzidine X-22-1660B-3: Both-terminal amine-modified methylphenyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.)
NMP 1: 500 ml bottled product left for one month after opening, water content 3,070 ppm
NMP2: A product in a 500 ml bottle left for one week after opening, with a water content of 1500 ppm.
NMP3: Immediately after opening the 18L can, water content 250ppm

As is clear from Tables 1 and 2, the resin compositions of Synthesis Examples 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, the polyimide precursor has a weight average molecular weight of 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 larger than that, and particularly good results are obtained. Specifically, it is possible to obtain 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.
Further, when the synthesis examples 1 and the examples 1 and 2 are compared, it can be seen that the smaller the water content of the solvent used for the polymerization reaction, the smaller the content of the molecule 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.
The polyimide precursor varnishes of Synthesis Example 1 and Examples and Comparative Examples were applied onto a mother glass substrate (thickness 0.7 mm) using a bar coater so as to have a film thickness of 10 μm after curing, and then at 140 ° C. Prebaked for 60 minutes. Subsequently, using a vertical curing furnace (manufactured by Koyo Lindbergh Co., Ltd., model name VF-2000B), the oxygen concentration in the refrigerator was adjusted to 10% by mass or less, and heat curing treatment was performed at 430 ° C. for 1 hour. A glass substrate on which a polyimide resin film was formed was produced.
Subsequently, a SiN layer was formed with a thickness of 100 nm by a CVD (Chemical Vapor Deposition) method.
Subsequently, titanium was formed into a film by a sputtering method, and then patterning was performed by a photolithography method to form a scanning signal line.
Next, a SiN layer was formed with a thickness of 100 nm on the entire glass substrate on which the scanning signal line was formed by a CVD method. (This is the lower board 2a)
Subsequently, an amorphous silicon layer 256 was formed on the lower substrate 2a, dehydrogenated and annealed at 430 ° C. for 1 hour, and then irradiated with an excimer laser to form an LTPS layer.

After that, the entire surface of the lower substrate 2a was coated with a photosensitive acrylic resin by a spin coating method, and exposed and developed by a photolithography method to form an interlayer insulating film 258 having a plurality of contact holes 257. A part of each LTPS 256 was exposed by the contact hole 257.
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, and patterned by an etching method to form a pair with each LTPS. The lower electrode 259 was formed as described above.
In each contact hole 257, the lower electrode 252 penetrating the interlayer insulating film 258 and the LTPS 256 were electrically connected.
Next, after the partition wall 251 was formed, the hole transport layer 253 and the light emitting layer 254 were formed in each space partitioned by the partition wall 251. Further, the upper electrode 255 was formed so as to cover the light emitting layer 254 and the partition wall 251. An organic EL substrate was produced by the above process.

Next, an ultraviolet curable resin is coated around the sealing substrate 2b in 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 placed in an argon gas atmosphere. By adhering, the organic EL element was enclosed. As a result, a hollow portion 261 was formed between each organic EL element and the sealing substrate 2b.
An excimer laser (wavelength 308 nm, repetition frequency 300 Hz) was irradiated from the lower substrate 2a side and the sealed substrate 2b side of the laminated body thus formed, and the entire surface was peeled with the minimum energy required for peeling. ..

This laminated body was evaluated for the presence or absence of substrate warpage after peeling, lighting test, and white turbidity evaluation of the laminated body. A heat cycle test was also conducted. The results are shown in Table 3.
<Board warp>
◎: No warp ○: Only a little warp △: Curled due to warp <Lighting test>
◯: Lighted ×: Not lit <Layer cloudiness evaluation>
After the laminated body was formed, it was visually observed, and the one in which the entire device was transparent was marked with ◯, the one with a slight cloudiness was marked with Δ, and the one with a cloudiness was marked with x.
<Heat cycle test>
Using a heat cycle tester manufactured by ESPEC, the appearance was observed after 1000 cycles of testing at -5 ° C and 60 ° C for 30 minutes (tank movement time 1 minute), respectively.
Those without peeling or swelling were marked with ◯, those with a small part of peeling or swelling after the test were marked with Δ, and those with full peeling or swelling after the test were marked with x.

As is clear from Table 3, in Examples 1 to 18 using the varnishes P-2 to P-19, there is no warpage of the substrate, the lighting test is good, there is no cloudiness, and good heat cycle characteristics are obtained. 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 for 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 the resin composition of the present invention, it is possible to obtain 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. Such a resin film can be applied to, for example, a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, etc., and can be particularly suitably used as a substrate in the manufacture of flexible displays, substrates for touch panel ITO electrodes, and the like. can.

2a Lower substrate 2b Encapsulation 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 (1)

The following general formula (5):

A polyimide layer containing a polyimide represented by (1) and a low-temperature polysilicon TFT layer are included.
The polyimide has a component derived from diamine.
・A component derived from diamine , which is a component derived from diaminodiphenyl sulfone,
-Ingredients derived from diaminodiphenyl sulfone and the following formula (3):

(A plurality of R ₃ and R ₄ existing in the formula are independently monovalent organic groups having 1 to 20 carbon atoms, and h is an integer of 3 to 200.)
It is a diamine-derived component containing a silicone diamine component containing a structure represented by, and the content of the silicone diamine component is 6% by mass when the total mass of the diamine component and the acid dianhydride component is 100% by mass. The diamine-derived component, which is less than or equal to 0.67 mol% or less when the total number of moles of the diamine-derived component is 100 mol% .
-A component derived from a diamine containing a component derived from diaminodiphenyl sulfone and a component derived from 4-aminophenyl-4-aminobenzoate, and the content of the component derived from 4-aminophenyl-4-aminobenzoate is the diamine. The diamine-derived component, which is 49 mol% or less when the total number of moles of the derived component is 100 mol%.
Is one of
In the polyimide, the component derived from acid dianhydride is a component derived from pyromellitic acid dianhydride, or a component derived from pyromellitic acid dianhydride and a component derived from biphenyltetracarboxylic acid dianhydride, and the acid dianhydride is used. When the total number of moles of the anhydride-derived component is 100 mol%, the content of the pyromellitic acid dianhydride-derived component is 80 mol% or more .
A laminate characterized in that the amount of molecules having a molecular weight of less than 1,000 contained in the polyimide layer is less than 5% by mass .

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