JP2022128480A - Polyimide precursor, resin composition, and method for producing resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible display that takes exceptional effect in terms of substrate warpage, a lighting test, a cloudiness test, and a heat cycle test.

SOLUTION: The flexible display comprises: a polyimide film layer containing a polyimide represented by general formula (13) in the figure {where X₁ represents a C4-32 tetravalent group; R₁, R₂ and R₃ each independently represent a C1-20 monovalent organic group; n represents 0 or 1; and a, b and c are each an integer from 0 to 4}; and a low-temperature polysilicon TFT layer formed on the polyimide film layer.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a method for producing a polyimide precursor, a resin composition, and a resin film, which are used, for example, in producing substrates for flexible devices.

In general, polyimide resin films are used as resin films for applications that require high heat resistance. A general polyimide resin is produced by solution polymerization of an aromatic carboxylic dianhydride and an aromatic diamine to produce a polyimide precursor, which is then thermally imidized at a high temperature, or chemically imidized using a catalyst. It is a highly heat-resistant resin manufactured by

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

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-treated 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 imidizing the polyimide precursor. Due to this heat treatment, residual stress is generated in the laminate, causing serious problems such as warping and peeling. This is because the coefficient of linear thermal expansion of polyimide is larger than that of the material constituting the support.

Polyimide formed from 3,3',4,4'-biphenyltetracarboxylic dianhydride and paraphenylenediamine is most well known as a polyimide material having a small coefficient of thermal expansion. 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).
Moreover, it has been reported that a polyimide having an ester structure in its molecular chain exhibits a low coefficient of linear thermal expansion because it has appropriate linearity and rigidity (Patent Document 1).

However, general polyimide resins, including the polyimides described in the above documents, are colored brown or yellow due to their high density of aromatic rings, and therefore have low light transmittance in the visible light region, and therefore require transparency. It is difficult to use in the field. For example, the polyimide of Non-Patent Document 1 obtained from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine has a yellowness index (YI value) of 40 or more at a film thickness of 10 μm. high and insufficient in terms of transparency.
As for the yellowness of the film, it is known that, for example, polyimide using a monomer having a fluorine atom exhibits an extremely low yellowness (Patent Document 2).

Patent No. 4627297 Japanese Patent Application Publication No. 2010-538103 Patent No. 3079867

The Latest Polyimides Edited by the Japan Polyimide Study Group NTS

By the way, in order to apply a polyimide resin as a colorless and transparent flexible substrate, mechanical properties such as excellent elongation and breaking strength are required in addition to transparency. In particular, recently, as the device type of TFTs has become LTPS (low-temperature polysilicon TFT), there has been a demand for a film that exhibits the above-mentioned physical properties even under a heat history greater than that in the past.
However, the physical properties of known transparent polyimides are not sufficient for use as heat-resistant colorless transparent substrates for displays.
Furthermore, as a result of confirmation by the present inventor, the polyimide resin described in Patent Document 1 exhibits a low linear thermal expansion coefficient, but the yellowness (YI value) of the polyimide resin film after peeling is large. It was found that there were problems such as high residual stress, low elongation, and low breaking strength.
Regarding the yellowness, the polyimide film described in Patent Document 2 exhibits a low yellowness in a temperature range of about 300 ° C., but in a high temperature range of 400 ° C. or higher, the yellowness (YI value) is significantly deteriorated. rice field.

Further, as a polyimide having a reduced linear expansion coefficient, a polyimide composed of 4,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl ester is disclosed (Patent Document 3).
However, when the present inventor confirmed, the polyimide resin described in Patent Document 3 has a very brittle film for application as a flexible substrate, and there is room for improvement in the degree of yellowness at high temperatures.

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

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝で示される構造単位Ｌと、
下記一般式（２）：

｛式中、Ｘ_２は炭素数４～３２の４価の基を表す。Ｙは下記一般式（３）である。｝で示される構造単位Ｍを、
１／９９≦（構造単位Ｌのモル数／構造単位Ｍのモル数）≦９９／１
で含むことを特徴とする、ポリイミド前駆体。

｛式中、Ｒ_４～Ｒ_５はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｅは０～４の整数である。｝
［２］
（ａ１）下記一般式（１）：

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝で示される構造単位Ｌと、
下記一般式（２）：

｛式中、Ｘ_２は炭素数４～３２の４価の基を表す。Ｙは下記一般式（４）である。｝で示される構造単位Ｍを、
１／９９≦（構造単位Ｌのモル数／構造単位Ｍのモル数）≦９９／１
で含むことを特徴とする、ポリイミド前駆体。

｛式中、Ｒ_６～Ｒ_９はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｆ～ｉは０～４の整数である。また、Ｚは、それぞれ独立に単結合、メチレン基、エチレン基、エーテルおよびケトンからなる群から選択される１種である。｝
［３］
前記一般式（１）におけるｎが０である、［１］または［２］に記載のポリイミド前駆体。
［４］
（ａ２）下記一般式（１０）：

で示される構造単位を有し、そして、重量平均分子量が３０，０００以上、３００，０００以下であることを特徴とするポリイミド前駆体。
｛式中、Ｘ_３は４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、およびビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）からなる群から選択される少なくとも１種に由来する４価の基を表す。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。｝
［５］
前記（ａ２）ポリイミド前駆体における、重量平均分子量１，０００未満の分子の含有量が５質量％未満である、［４］に記載のポリイミド前駆体。
［６］
一般式（１０）におけるｎが０である、［４］または［５］に記載のポリイミド前駆体。
［７］
（ａ１）下記一般式（１）：

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝で示される構造単位Ｌと、
下記一般式（２）：

｛式中、Ｘ_２は炭素数４～３２の４価の基を表す。Ｙは下記一般式（３）、（４）および（５）からなる群から選択される少なくとも１種である。｝で示される構造単位Ｍを、
１／９９≦（構造単位Ｌのモル数／構造単位Ｍのモル数）≦９９／１
で含み、

｛式中、Ｒ_４～Ｒ_１１はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｋは０～４の整数である。また、一般式（４）中のＺは、それぞれ独立に単結合、メチレン基、エチレン基、エーテルおよびケトンからなる群から選択される１種である。｝
前記Ｘ_１、Ｘ_２が、４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、およびビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）、からなる群から選択される少なくとも１種に由来する４価の有機基であるポリイミド前駆体。
［８］
［１］～［７］のいずれかに記載のポリイミド前駆体と、（ｂ）有機溶剤と、を含有することを特徴とする、樹脂組成物。
［９］
更に、（ｃ）界面活性剤、および（ｄ）アルコキシシラン化合物、からなる群から選択される少なくとも１種を含む、［８］に記載の樹脂組成物。
［１０］
下記一般式（１１）：

｛式中、Ｘ_１、Ｘ_２は炭素数４～３２の４価の基を表す。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。Ｙは下記一般式（３）、および（４）からなる群から選択される少なくとも１種である。ｌ、ｍはそれぞれ独立に１以上の整数を表し、０．０１≦ｌ／（ｌ＋ｍ）≦０．９９を満たす。｝で表される構造単位を有することを特徴とする、ポリイミド。

｛式中、Ｒ_４～Ｒ_９はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｉは０～４の整数である。また、一般式（４）中のＺは、それぞれ独立に単結合、メチレン基、エチレン基、エーテルおよびケトンからなる群から選択される１種である。｝
［１１］
下記一般式（１２）：

｛式中、Ｘ_３は４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、およびビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）からなる群から選択される少なくとも１種に由来する４価の基を表す。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。｝で表される構造単位を有し、伸度が１５％以上であることを特徴とする、ポリイミド。
［１２］
支持体の表面上に、［８］または［９］に記載の樹脂組成物を塗布することにより塗膜を形成する工程と、
前記支持体及び前記塗膜を加熱することにより、該塗膜に含まれるポリイミド前駆体をイミド化して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。
［１３］
支持体の表面上に、樹脂組成物を塗布することにより塗膜を形成する工程と、
前記支持体及び前記塗膜を加熱することにより、該塗膜に含まれるポリイミド前駆体をイミド化して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、を含み、
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、樹脂フィルムの製造方法であって、
前記樹脂組成物が、
（ａ１）下記一般式（１）：

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝で示される構造単位Ｌと、
下記一般式（２）：

｛式中、Ｘ_２は炭素数４～３２の４価の基を表す。Ｙは下記一般式（３）、（４）および（５）からなる群から選択される少なくとも１種である。｝で示される構造単位Ｍを、
１／９９≦（構造単位Ｌのモル数／構造単位Ｍのモル数）≦９９／１で含む、ポリイミド前駆体と、

｛式中、Ｒ_４～Ｒ_１１はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｋは０～４の整数である。また、一般式（４）中のＺは、それぞれ独立に単結合、メチレン基、エチレン基、エーテルおよびケトンからなる群から選択される１種である。｝
（ｂ）有機溶剤と、を含有することを特徴とする、樹脂フィルムの製造方法。
［１４］
前記樹脂組成物が、更に、（ｃ）界面活性剤、および（ｄ）アルコキシシラン化合物、からなる群から選択される少なくとも１種を含む、［１３］に記載の樹脂フィルムの製造方法。
［１５］
支持体の表面上に、［８］または［９］に記載の樹脂組成物を塗布することにより塗膜を形成する工程と、
前記支持体及び前記塗膜を加熱することにより、該塗膜に含まれるポリイミド前駆体をイミド化してポリイミド樹脂膜を形成する工程と、
を含むことを特徴とする、積層体の製造方法。
［１６］
支持体の表面上に、樹脂組成物を塗布することにより塗膜を形成する工程と、
前記支持体及び前記塗膜を加熱することにより、該塗膜に含まれるポリイミド前駆体をイミド化して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素子又は回路を形成する工程と、
前記素子又は回路が形成された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、ディスプレイ基板の製造方法であって、
前記樹脂組成物が、
（ａ１）下記一般式（１）：

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝で示される構造単位Ｌと、
下記一般式（２）：

｛式中、Ｘ_２は炭素数４～３２の４価の基を表す。Ｙは下記一般式（３）、（４）および（５）からなる群から選択される少なくとも１種である。｝で示される構造単位Ｍを、
１／９９≦（構造単位Ｌのモル数／構造単位Ｍのモル数）≦９９／１で含む、ポリイミド前駆体と、

｛式中、Ｒ_４～Ｒ_１１はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｋは０～４の整数である。また、一般式（４）中のＺは、それぞれ独立に単結合、メチレン基、エチレン基、エーテルおよびケトンからなる群から選択される１種である。｝
（ｂ）有機溶剤と、を含有することを特徴とする、ディスプレイ基板の製造方法。
［１７］
前記樹脂組成物が、更に、（ｃ）界面活性剤、および（ｄ）アルコキシシラン化合物、からなる群から選択される少なくとも１種を含む、［１６］に記載のディスプレイ基板の製造方法。
［１８］
下記一般式（１２）：

｛式中、Ｘ_３は４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、およびビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）からなる群から選択される少なくとも１種であり、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。｝
で表されるポリイミドを含むことを特徴とする、ディスプレイ用ポリイミドフィルム。
［１９］
下記一般式（１３）：

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝で表されるポリイミドを含むポリイミドフィルム層と、前記ポリイミド層上に形成された低温ポリシリコンＴＦＴ層と、を含む、フレキシブルディスプレイであって、
前記ポリイミドフィルム層は、
下記一般式（１２）：

｛式中、Ｘ_３は４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、およびビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）からなる群から選択される少なくとも１種であり、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。｝
で表されるポリイミド、又は、
下記一般式（１１）：

｛式中、Ｘ_１、Ｘ_２は炭素数４～３２の４価の基を表す。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。Ｙは下記一般式（３）、（４）、（５）からなる群から選択される少なくとも１種である。ｌ、ｍはそれぞれ独立に１以上の整数を表し、０．０１≦ｌ／（ｌ＋ｍ）≦０．９９を満たす。｝で表される構造単位を有するポリイミド

｛式中、Ｒ_４～Ｒ_１１はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｋは０～４の整数である。また、一般式（４）中のＺは、それぞれ独立に単結合、メチレン基、エチレン基、エーテルおよびケトンからなる群から選択される１種である。｝から選択される少なくとも１つのポリイミドを含むことを特徴とする、フレキシブルディスプレイ。
［２０］
支持体の表面上に、樹脂組成物を塗布することにより塗膜を形成する工程と、
前記支持体及び前記塗膜を加熱することにより、該塗膜に含まれるポリイミド前駆体をイミド化して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、を含み、
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、樹脂フィルムの製造方法であって、
前記樹脂組成物は、
（ａ）下記一般式（１）で表されるポリイミド前駆体と、
（ｂ）有機溶剤と、
（ｃ）界面活性剤および（ｄ）アルコキシシラン化合物からなる群から選択される少なくとも１種と、
を含み、

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝
前記ポリイミド樹脂膜は、
下記一般式（１２）：

｛式中、Ｘ_３は４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、およびビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）からなる群から選択される少なくとも１種であり、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。｝
で表されるポリイミド、又は、
下記一般式（１１）：

｛式中、Ｘ_１、Ｘ_２は炭素数４～３２の４価の基を表す。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。Ｙは下記一般式（３）、（４）からなる群から選択される少なくとも１種である。ｌ、ｍはそれぞれ独立に１以上の整数を表し、０．０１≦ｌ／（ｌ＋ｍ）≦０．９９を満たす。｝で表される構造単位を有するポリイミド

｛式中、Ｒ_４～Ｒ_９はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｉは０～４の整数である。また、一般式（４）中のＺは、それぞれ独立に単結合、メチレン基、エチレン基、エーテルおよびケトンからなる群から選択される１種である。｝から選択される少なくとも１つのポリイミドを含むことを特徴とする、樹脂フィルムの製造方法。
［２１］
支持体の表面上に、樹脂組成物を塗布することにより塗膜を形成する工程と、
前記支持体及び前記塗膜を加熱することにより、該塗膜に含まれるポリイミド前駆体をイミド化して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素子又は回路を形成する工程と、
前記素子又は回路が形成された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、ディスプレイ基板の製造方法であって、
前記樹脂組成物は、
（ａ）下記一般式（１）で表されるポリイミド前駆体と、
（ｂ）有機溶剤と、
（ｃ）界面活性剤および（ｄ）アルコキシシラン化合物からなる群から選択される少なくとも１種と、
を含み、

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝
前記ポリイミド樹脂膜は、
下記一般式（１２）：

｛式中、Ｘ_３は４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、およびビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）からなる群から選択される少なくとも１種であり、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。｝
で表されるポリイミド、又は、
下記一般式（１１）：

｛式中、Ｘ_１、Ｘ_２は炭素数４～３２の４価の基を表す。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。Ｙは下記一般式（３）、（４）、（５）からなる群から選択される少なくとも１種である。ｌ、ｍはそれぞれ独立に１以上の整数を表し、０．０１≦ｌ／（ｌ＋ｍ）≦０．９９を満たす。｝で表される構造単位を有するポリイミド

｛式中、Ｒ_４～Ｒ_１１はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｋは０～４の整数である。また、一般式（４）中のＺは、それぞれ独立に単結合、メチレン基、エチレン基、エーテルおよびケトンからなる群から選択される１種である。｝から選択される少なくとも１つのポリイミドを含むことを特徴とする、ディスプレイ基板の製造方法。 The present invention is as follows.
[1]
(a1) the following general formula (1):

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. } and a structural unit L represented by
The following general formula (2):

{In the formula, X ₂ represents a tetravalent group having 4 to 32 carbon atoms. Y is the following general formula (3). }, the structural unit M represented by
1/99 ≤ (number of moles of structural unit L/number of moles of structural unit M) ≤ 99/1
A polyimide precursor comprising:

{In the formula, R ₄ to R ₅ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to e are integers from 0 to 4; }
[2]
(a1) the following general formula (1):

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. } and a structural unit L represented by
The following general formula (2):

{In the formula, X ₂ represents a tetravalent group having 4 to 32 carbon atoms. Y is the following general formula (4). }, the structural unit M represented by
1/99 ≤ (number of moles of structural unit L/number of moles of structural unit M) ≤ 99/1
A polyimide precursor comprising:

{In the formula, R ₆ to R ₉ each independently represent a monovalent organic group having 1 to 20 carbon atoms. f to i are integers from 0 to 4; Moreover, each Z is independently one selected from the group consisting of a single bond, a methylene group, an ethylene group, an ether and a ketone. }
[3]
The polyimide precursor according to [1] or [2], wherein n in the general formula (1) is 0.
[4]
(a2) the following general formula (10):

and a weight average molecular weight of 30,000 or more and 300,000 or less.
{Wherein, X ₃ is a tetravalent group derived from at least one selected from the group consisting of 4,4′-oxydiphthalic dianhydride (ODPA) and biphenyltetracarboxylic dianhydride (BPDA) show. 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 0-4. }
[5]
The polyimide precursor according to [4], wherein the content of molecules having a weight average molecular weight of less than 1,000 in the (a2) polyimide precursor is less than 5% by mass.
[6]
The polyimide precursor according to [4] or [5], wherein n in the general formula (10) is 0.
[7]
(a1) the following general formula (1):

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. } and a structural unit L represented by
The following general formula (2):

{In the formula, X ₂ represents a tetravalent group having 4 to 32 carbon atoms. Y is at least one selected from the group consisting of the following general formulas (3), (4) and (5). }, the structural unit M represented by
1/99 ≤ (number of moles of structural unit L/number of moles of structural unit M) ≤ 99/1
contains in

{In the formula, R ₄ to R ₁₁ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to k are integers from 0 to 4; Moreover, each Z in the general formula (4) is one selected from the group consisting of a single bond, a methylene group, an ethylene group, an ether and a ketone. }
X _{1 and} X ₂ are tetravalent dianhydrides derived from at least one selected from the group consisting of 4,4′-oxydiphthalic dianhydride (ODPA) and biphenyltetracarboxylic dianhydride (BPDA) A polyimide precursor that is an organic group.
[8]
A resin composition comprising the polyimide precursor according to any one of [1] to [7] and (b) an organic solvent.
[9]
The resin composition according to [8], further comprising at least one selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.
[10]
The following general formula (11):

{In the formula, X _{1 and} X ₂ represent a tetravalent group having 4 to 32 carbon atoms. 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 0-4. Y is at least one selected from the group consisting of the following general formulas (3) and (4). l and m each independently represent an integer of 1 or more and satisfy 0.01≦l/(l+m)≦0.99. }, characterized by having a structural unit represented by.

{In the formula, R ₄ to R ₉ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to i are integers from 0 to 4; Moreover, each Z in the general formula (4) is one selected from the group consisting of a single bond, a methylene group, an ethylene group, an ether and a ketone. }
[11]
The following general formula (12):

{Wherein, X ₃ is a tetravalent group derived from at least one selected from the group consisting of 4,4′-oxydiphthalic dianhydride (ODPA) and biphenyltetracarboxylic dianhydride (BPDA) show. 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 0-4. } and has an elongation of 15% or more.
[12]
A step of forming a coating film by applying the resin composition according to [8] or [9] on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
a step of peeling the polyimide resin film from the support;
A method for producing a resin film, comprising:
[13]
a step of forming a coating film by applying a resin composition on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
and a step of peeling the polyimide resin film from the support,
A method for producing a resin film, 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,
The resin composition is
(a1) the following general formula (1):

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. } and a structural unit L represented by
The following general formula (2):

{In the formula, X ₂ represents a tetravalent group having 4 to 32 carbon atoms. Y is at least one selected from the group consisting of the following general formulas (3), (4) and (5). }, the structural unit M represented by
1/99≦(number of moles of structural unit L/number of moles of structural unit M)≦99/1; and

{In the formula, R ₄ to R ₁₁ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to k are integers from 0 to 4; Moreover, each Z in the general formula (4) is one selected from the group consisting of a single bond, a methylene group, an ethylene group, an ether and a ketone. }
(b) a method for producing a resin film, characterized by containing an organic solvent;
[14]
The method for producing a resin film according to [13], wherein the resin composition further contains at least one selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.
[15]
A step of forming a coating film by applying the resin composition according to [8] or [9] on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
A method for manufacturing a laminate, comprising:
[16]
a step of forming a coating film by applying a resin composition on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
forming an element or circuit on the polyimide resin film;
a step of peeling off the polyimide resin film on which the element or circuit is formed from the support;
A method of manufacturing a display substrate, comprising:
The resin composition is
(a1) the following general formula (1):

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. } and a structural unit L represented by
The following general formula (2):

{In the formula, X ₂ represents a tetravalent group having 4 to 32 carbon atoms. Y is at least one selected from the group consisting of the following general formulas (3), (4) and (5). }, the structural unit M represented by
1/99≦(number of moles of structural unit L/number of moles of structural unit M)≦99/1; and

{In the formula, R ₄ to R ₁₁ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to k are integers from 0 to 4; Moreover, each Z in the general formula (4) is one selected from the group consisting of a single bond, a methylene group, an ethylene group, an ether and a ketone. }
(b) a method for producing a display substrate, characterized by containing an organic solvent;
[17]
The method for producing a display substrate according to [16], wherein the resin composition further contains at least one selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.
[18]
The following general formula (12):

{wherein X ₃ is at least one selected from the group consisting of 4,4' _- oxydiphthalic dianhydride ( _ODPA ) and biphenyltetracarboxylic dianhydride (BPDA); , 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 0-4. }
A polyimide film for a display, comprising a polyimide represented by:
[19]
The following general formula (13):

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. } and a low-temperature polysilicon TFT layer formed on the polyimide layer, wherein
The polyimide film layer is
The following general formula (12):

{wherein X ₃ is at least one selected from the group consisting of 4,4' _- oxydiphthalic dianhydride ( _ODPA ) and biphenyltetracarboxylic dianhydride (BPDA); , 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 0-4. }
Polyimide represented by, or
The following general formula (11):

{In the formula, X _{1 and} X ₂ represent a tetravalent group having 4 to 32 carbon atoms. 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 0-4. Y is at least one selected from the group consisting of the following general formulas (3), (4) and (5). l and m each independently represent an integer of 1 or more and satisfy 0.01≦l/(l+m)≦0.99. } polyimide having a structural unit represented by

{In the formula, R ₄ to R ₁₁ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to k are integers from 0 to 4; Moreover, each Z in the general formula (4) is one selected from the group consisting of a single bond, a methylene group, an ethylene group, an ether and a ketone. }, comprising at least one polyimide selected from:
[20]
a step of forming a coating film by applying a resin composition on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
and a step of peeling the polyimide resin film from the support,
A method for producing a resin film, 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,
The resin composition is
(a) a polyimide precursor represented by the following general formula (1);
(b) an organic solvent;
(c) a surfactant and (d) at least one selected from the group consisting of an alkoxysilane compound;
including

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. }
The polyimide resin film is
The following general formula (12):

{wherein X ₃ is at least one selected from the group consisting of 4,4' _- oxydiphthalic dianhydride ( _ODPA ) and biphenyltetracarboxylic dianhydride (BPDA); , 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 0-4. }
Polyimide represented by, or
The following general formula (11):

{In the formula, X _{1 and} X ₂ represent a tetravalent group having 4 to 32 carbon atoms. 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 0-4. Y is at least one selected from the group consisting of the following general formulas (3) and (4). l and m each independently represent an integer of 1 or more and satisfy 0.01≦l/(l+m)≦0.99. } polyimide having a structural unit represented by

{In the formula, R ₄ to R ₉ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to i are integers from 0 to 4; Moreover, each Z in the general formula (4) is one selected from the group consisting of a single bond, a methylene group, an ethylene group, an ether and a ketone. }, a method for producing a resin film, comprising at least one polyimide selected from
[21]
a step of forming a coating film by applying a resin composition on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
forming an element or circuit on the polyimide resin film;
a step of peeling off the polyimide resin film on which the element or circuit is formed from the support;
A method of manufacturing a display substrate, comprising:
The resin composition is
(a) a polyimide precursor represented by the following general formula (1);
(b) an organic solvent;
(c) a surfactant and (d) at least one selected from the group consisting of an alkoxysilane compound;
including

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. }
The polyimide resin film is
The following general formula (12):

{wherein X ₃ is at least one selected from the group consisting of 4,4' _- oxydiphthalic dianhydride ( _ODPA ) and biphenyltetracarboxylic dianhydride (BPDA); , 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 0-4. }
Polyimide represented by, or
The following general formula (11):

{In the formula, X _{1 and} X ₂ represent a tetravalent group having 4 to 32 carbon atoms. 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 0-4. Y is at least one selected from the group consisting of the following general formulas (3), (4) and (5). l and m each independently represent an integer of 1 or more and satisfy 0.01≦l/(l+m)≦0.99. } polyimide having a structural unit represented by

{In the formula, R ₄ to R ₁₁ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to k are integers from 0 to 4; Moreover, each Z in the general formula (4) is one selected from the group consisting of a single bond, a methylene group, an ethylene group, an ether and a ketone. }, comprising at least one polyimide selected from }.

A polyimide film obtained from a polyimide precursor and a resin composition according to the present invention has low residual stress, little warpage, a small yellowness index (YI value), and high elongation.

FIG. 4 is a diagram showing the structure of an organic EL substrate produced in Examples and Comparative Examples;

Exemplary embodiments of the present invention (hereinafter abbreviated as "embodiments") will be described in detail below. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention. In addition, unless otherwise specified, the characteristic values described in the present disclosure are values measured by the method described in the [Examples] section or a method understood to be equivalent thereto by a person skilled in the art. Intend.

<Resin composition>
A resin composition provided by one aspect of the present invention contains (a) a polyimide precursor and (b) an organic solvent.
Each component will be described in order below.

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝で示される構造単位Ｌと、
下記一般式（２）：

｛式中、Ｘ_２は炭素数４～３２の４価の基を表す。Ｙは下記一般式（３）、（４）および（５）からなる群から選択される少なくとも１種である｝で示される構造単位Ｍとを
１／９９≦（構造単位Ｌのモル数／構造単位Ｍのモル数）≦９９／１で含むことを特徴とする、ポリイミド前駆体である。

｛式中、Ｒ_４～Ｒ_１１はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ～ｋは０～４の整数である。｝
本実施の第一の態様のポリイミド前駆体は、ポリイミドフィルムとしたときに残留応力が低く、反りが少なく、黄色度（ＹＩ値）が小さく、伸度が高い。また、本実施の第一の態様のポリイミド前駆体は、ポリイミドフィルムとしたときに、高温領域での黄色度（ＹＩ値）が小さい。
ここで、Ｒ_１～Ｒ_３はそれぞれ独立に炭素数１～２０の１価の有機基であれば限定されない。このような有機基として、メチル基、エチル基、プロピル基などのアルキル基、トリフルオロメチル基などのハロゲン含有基、メトキシ基、エトキシ基などのアルコキシ基、などが挙げられる。この中で、高温領域でのＹＩの観点から、メチル基が好ましい。
ここで、ａ、ｂ、ｃ、ｄは０～４の整数であれば限定されない。この中で、ＹＩ、残留応力の観点から０～２の整数が好ましく、高温領域でのＹＩの観点から、０が特に好ましい。
ここで、ｎは０または１である。この中で、高温領域でのＹＩの観点から、０が好ましい。 [Polyimide precursor]
The polyimide precursor as a first aspect of the present implementation is
(a1) the following general formula (1):

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. } and a structural unit L represented by
The following general formula (2):

{In the formula, X ₂ represents a tetravalent group having 4 to 32 carbon atoms. Y is at least one selected from the group consisting of the following general formulas (3), (4) and (5)} and the structural unit M represented by 1/99 ≤ (number of moles of structural unit L / structure The number of moles of the unit M) ≤ 99/1 is a polyimide precursor.

{In the formula, R ₄ to R ₁₁ each independently represent a monovalent organic group having 1 to 20 carbon atoms. d to k are integers from 0 to 4; }
When the polyimide precursor of the first aspect of the present invention is made into a polyimide film, it has low residual stress, little warpage, small yellowness (YI value), and high elongation. In addition, the polyimide precursor of the first aspect of the present embodiment has a small yellowness index (YI value) in a high temperature range when formed into a polyimide film.
Here, R ₁ to R ₃ are not limited as long as they are each independently a monovalent organic group having 1 to 20 carbon atoms. Examples of such organic groups include alkyl groups such as methyl group, ethyl group and propyl group, halogen-containing groups such as trifluoromethyl group, and alkoxy groups such as methoxy group and ethoxy group. Among these, a methyl group is preferable from the viewpoint of YI in a high temperature range.
Here, a, b, c, and d are not limited as long as they are integers from 0 to 4. Among these, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.
Here, n is 0 or 1. Among these, 0 is preferable from the viewpoint of YI in the high temperature region.

Further, the lower limit of the molar ratio of the structural unit L to the structural unit M (the number of moles of the structural unit L/the number of moles of the structural unit M) may be 5/95, 10/90, 20/80, or 30. /70 or 40/60. The upper limit of the molar ratio of the structural unit L to the structural unit M (the number of moles of the structural unit L/the number of moles of the structural unit M) may be 95/5, 90/10, 80/20, or 70/30. , or 60/40.
X ₁ and X ₂ are each independently a tetravalent group having 4 to 32 carbon atoms and may be the same or different. Tetravalent organic groups derived from the following tetracarboxylic dianhydrides are exemplified.
Specific examples of the tetracarboxylic dianhydride include aromatic tetracarboxylic dianhydride having 8 to 36 carbon atoms, aliphatic tetracarboxylic dianhydride having 6 to 36 carbon atoms, and carbon number can be exemplified by compounds selected from alicyclic tetracarboxylic acid dianhydrides having 6 to 36. Among these, aromatic tetracarboxylic dianhydrides having 8 to 36 carbon atoms are preferred from the viewpoint of yellowness in a high temperature range. The number of carbon atoms as used herein also includes the number of carbon atoms contained in the carboxyl group.

More specifically, examples of aromatic tetracarboxylic dianhydrides having 8 to 36 carbon atoms include 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (hereinafter also referred to as 6FDA), 5-( 2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2 dicarboxylic anhydride, pyromellitic dianhydride (hereinafter also referred to as PMDA), 1,2,3,4-benzene Tetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 2,2′,3,3′-benzophenonetetracarboxylic dianhydride, 3,3′,4, 4'-biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride Carboxylic dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethylidene-4,4'-diphthalic dianhydride, 2,2-propylidene-4,4'-diphthalic dianhydride anhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic acid dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride (hereinafter also referred to as ODPA), p-phenylenebis(trimellitate anhydride ) (hereinafter also referred to as TAHQ) thio-4,4′-diphthalic dianhydride, sulfonyl-4,4′-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene di anhydride, 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-dicarboxy phenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1 , 3-bis(3,4- dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride anhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride , 1,2,7,8-phenanthrenetetracarboxylic dianhydride and the like.

Examples of aliphatic tetracarboxylic dianhydrides having 6 to 50 carbon atoms include ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, and the like;
Alicyclic tetracarboxylic dianhydrides having 6 to 36 carbon atoms, such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1,2, 3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride (hereinafter referred to as CHDA), 3,3′,4,4′-bicyclohexyltetracarboxylic acid dianhydride, carbonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1, 2-ethylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 2,2-propylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio- 4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2,2,2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, rel-[1S,5R,6R]-3-oxabicyclo[3,2,1]octane-2,4-dione- 6-spiro-3′-(tetrahydrofuran-2′,5′-dione), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2- Examples thereof include dicarboxylic anhydrides, ethylene glycol-bis-(3,4-dicarboxylic anhydride phenyl) ethers, and the like.

PMDA, BPDA, TAHQ and ODPA are preferable, and BPDA and TAHQ are more preferable, from the viewpoint of CTE, chemical resistance, balance between Tg and yellowness in a high temperature range.

The polyimide precursor in the embodiment may be a polyamideimide precursor by using a dicarboxylic acid in addition to the tetracarboxylic dianhydride described above as long as the performance is not impaired. By using such a precursor, it is possible to adjust various performances such as improvement in mechanical elongation, improvement in glass transition temperature and reduction in yellowness in the resulting film. Such dicarboxylic acids include dicarboxylic acids having aromatic rings and alicyclic dicarboxylic acids. Particularly preferred is 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 as used herein also includes the number of carbon atoms contained in the carboxyl group.
Among these, dicarboxylic acids having an aromatic ring are preferred.

Specifically, for example, isophthalic acid, terephthalic acid, 4,4′-biphenyldicarboxylic acid, 3,4′-biphenyldicarboxylic acid, 3,3′-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3 -naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-sulfonylbisbenzoic acid, 3,4'-sulfonylbisbenzoic acid, 3,3'-sulfonylbisbenzoic acid , 4,4′-oxybisbenzoic acid, 3,4′-oxybisbenzoic acid, 3,3′-oxybisbenzoic acid, 2,2-bis(4-carboxyphenyl)propane, 2,2-bis(3-carboxy phenyl)propane, 2,2'-dimethyl-4,4'-biphenyldicarboxylic acid, 3,3'-dimethyl-4,4'-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-terphenyl 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-phenylenediacetic acid, 1,4-phenylenediacetic acid, etc.; and acid derivatives. When these dicarboxylic acids are actually copolymerized with a polymer, they may be used in the form of acid chlorides or active esters derived from thionyl chloride or the like.

The weight average molecular weight (Mw) of the polyimide precursor in the present embodiment is preferably 10,000 to 300,000, particularly preferably 30,000 to 200,000. When the weight average molecular weight is more than 10,000, the mechanical properties such as elongation and breaking strength are excellent, the residual stress is low, and the YI is low. When the weight-average molecular weight is less than 300,000, it becomes easier to control the weight-average molecular weight during the synthesis of the polyamic acid, a resin composition having an appropriate viscosity can be obtained, and the coating properties of the resin composition are improved. In the present disclosure, the weight average molecular weight is a value obtained as a standard polystyrene conversion value using gel permeation chromatography (hereinafter also referred to as GPC).
In the polyimide precursor of the present embodiment, the content of molecules having a molecular weight of less than 1,000 is preferably less than 5% by mass, more preferably less than 1% by mass, relative to the total amount of the polyimide precursor. preferable. A polyimide film formed from a resin composition obtained using such a polyimide precursor has a low residual stress, which is preferable from the viewpoint that an inorganic film formed on the polyimide film has a low haze.
The content of molecules having a molecular weight of less than 1,000 with respect to the total amount of the polyimide precursor can be calculated from the peak area obtained by GPC measurement using a solution in which the polyimide precursor is dissolved.

（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。）
Ｒ_１、Ｒ_２としては、メチル基、エチル基、プロピル基などのアルキル基、トリフルオロメチル基などのハロゲン含有基、メトキシ基、エトキシ基などのアルコキシ基、などが挙げられる。この中で、高温領域でのＹＩの観点から、メチル基が好ましい。
ここで、ａ、ｂは０～４の整数であれば限定されない。この中で、ＹＩ、残留応力の観点から０～２の整数が好ましく、高温領域でのＹＩの観点から、０が特に好ましい。
より具体的には、ｎが０の場合は、４－アミノフェニル－４－アミノベンゾエート（ＡＰＡＢ）、２－メチル－４－アミノフェニル－４－アミノベンゾエート（ＡＴＡＢ）、４－アミノフェニル－３－アミノベンゾエート（４，３－ＡＰＡＢ）などを例示することができる。
ｎが１の場合は、［４－（４－アミノベンゾイル）オキシフェニル］４－アミノベンゾエートなどを例示することができる。
本実施の形態における一般式（３）で表される構造単位に用いられるジアミンとしては、下記一般式（７）で表されるジアミンを例示することができる。

（式中、Ｒ_４、Ｒ_５はそれぞれ独立に炭素数１～２０の１価の有機基を表す。ｄ、ｅは０～４の整数である。）
ここで、Ｒ_４、Ｒ_５はそれぞれ独立に炭素数１～２０の１価の有機基であれば限定されない。このような有機基として、メチル基、エチル基、プロピル基などのアルキル基、トリフルオロメチル基などのハロゲン含有基、メトキシ基、エトキシ基などのアルコキシ基、などが挙げられる。この中で、高温領域でのＹＩの観点から、メチル基が好ましい。
ここで、ｃ、ｄは０～４の整数であれば限定されない。この中で、ＹＩ、残留応力の観点から０～２の整数が好ましく、高温領域でのＹＩの観点から、０が特に好ましい。
より具体的には、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。
本実施の形態における一般式（４）で表される構造単位に用いられるジアミンとしては、下記一般式（８）で表されるジアミンを例示することができる。

ここで、Ｒ_６及びＲ_７はそれぞれ独立に炭素数１～２０の１価の有機基であれば限定されない。このような有機基として、例えば、メチル基、エチル基、プロピル基等のアルキル基；トリフルオロメチル基等のハロゲン含有基；メトキシ基、エトキシ基等のアルコキシ基；等が挙げられる。この中で、高温領域でのＹＩの観点から、メチル基が好ましい。
Ｒ_８とＲ_９はそれぞれ独立に炭素数１～２０の１価の有機基、水酸基、又はハロゲン原子であれば限定されない。上記の有機基としては、例えば、メチル基、エチル基、プロピル基等のアルキル基；トリフルオロメチル基等のハロゲン含有基；メトキシ基、エトキシ基等のアルコキシ基；等が挙げられる。ハロゲン原子としては、例えば、フッ素原子、塩素原子、臭素原子、ヨウ素原子等が挙げられる。
ｆ、ｇ、ｈ、及びｉはそれぞれ独立に０～４の整数であれば限定されない。この中で、ＹＩ、残留応力の観点から０～２の整数が好ましく、高温領域でのＹＩの観点から、０が特に好ましい。
Ｚは単結合、メチレン基、エチレン基、エーテル、ケトンなどが例示できる。この中で、高温領域でのＹＩの観点から、単結合がより好ましい。
より具体的には、９，９－ビス（アミノフェニル）フルオレン、９，９－ビス（４－アミノ－３－メチルフェニル）フルオレン、９，９－ビス（４－アミノ－３－フルオロフェニル）フルオレン、９，９－ビス（４－ヒドロキシ－３－アミノフェニル）フルオレン、９，９－ビス［４－（４－アミノフェノキシ）フェニル］フルオレン等を例示することができ、これらのうちから選択される１種以上を使用することが好ましい。 Examples of the diamine used for the structural unit represented by the general formula (1) in the present embodiment include diamines represented by the following general formula (6).

(wherein 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; a, b and c are integers of 0 to 4; is.)
Examples of R ₁ and R ₂ include alkyl groups such as methyl group, ethyl group and propyl group, halogen-containing groups such as trifluoromethyl group, alkoxy groups such as methoxy group and ethoxy group, and the like. Among these, a methyl group is preferable from the viewpoint of YI in a high temperature range.
Here, a and b are not limited as long as they are integers from 0 to 4. Among these, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.
More specifically, when n is 0, 4-aminophenyl-4-aminobenzoate (APAB), 2-methyl-4-aminophenyl-4-aminobenzoate (ATAB), 4-aminophenyl-3- Aminobenzoate (4,3-APAB) and the like can be exemplified.
When n is 1, [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate and the like can be exemplified.
Examples of the diamine used for the structural unit represented by the general formula (3) in the present embodiment include diamines represented by the following general formula (7).

(In the formula, R _{4 and} R ₅ each independently represent a monovalent organic group having 1 to 20 carbon atoms, and d and e are integers of 0 to 4.)
Here, R _{4 and} R ₅ are not limited as long as they are each independently a monovalent organic group having 1 to 20 carbon atoms. Examples of such organic groups include alkyl groups such as methyl group, ethyl group and propyl group, halogen-containing groups such as trifluoromethyl group, and alkoxy groups such as methoxy group and ethoxy group. Among these, a methyl group is preferable from the viewpoint of YI in a high temperature range.
Here, c and d are not limited as long as they are integers from 0 to 4. Among these, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.
More specifically, 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone can be exemplified.
Examples of the diamine used for the structural unit represented by the general formula (4) in the present embodiment include diamines represented by the following general formula (8).

Here, R ₆ and R ₇ are not limited as long as they are independently monovalent organic groups having 1 to 20 carbon atoms. Examples of such organic groups include alkyl groups such as methyl group, ethyl group and propyl group; halogen-containing groups such as trifluoromethyl group; alkoxy groups such as methoxy group and ethoxy group; Among these, a methyl group is preferable from the viewpoint of YI in a high temperature range.
Each of R ₈ and R ₉ is not limited as long as it is independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, or a halogen atom. Examples of the above organic groups include alkyl groups such as methyl group, ethyl group and propyl group; halogen-containing groups such as trifluoromethyl group; alkoxy groups such as methoxy group and ethoxy group; Halogen atoms include, for example, fluorine, chlorine, bromine, and iodine atoms.
f, g, h, and i are not limited as long as they are independently integers of 0 to 4. Among these, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.
Z can be exemplified by single bond, methylene group, ethylene group, ether, ketone and the like. Among these, a single bond is more preferable from the viewpoint of YI in a high temperature region.
More specifically, 9,9-bis(aminophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 9,9-bis(4-amino-3-fluorophenyl)fluorene , 9,9-bis(4-hydroxy-3-aminophenyl)fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, etc., selected from among these It is preferred to use one or more.

ここで、Ｒ_１０及びＲ_１１はそれぞれ独立に炭素数１～２０の１価の有機基であれば限定されない。このような有機基として、例えば、メチル基、エチル基、プロピル基等のアルキル基；トリフルオロメチル基等のハロゲン含有基；メトキシ基、エトキシ基等のアルコキシ基；等が挙げられる。この中で、高温領域でのＹＩの観点から、メチル基が好ましい。
また、ｊ、ｋはそれぞれ独立に０～４の整数であれば限定されない。この中で、ＹＩ、残留応力の観点から０～２の整数が好ましく、高温領域でのＹＩの観点から、０が特に好ましい。
より具体的には、２、２’－ビス（トリフルオロメチル）ベンジジンなどを例示することができる。
本実施の第一の態様のポリイミド前駆体から形成されるポリイミドフィルムは、残留応力が低く、反りが少なく、高温領域での黄色度（ＹＩ値）が小さく、伸度が高い。 Examples of the diamine used for the structural unit represented by the general formula (5) in the present embodiment include diamines represented by the following general formula (9).

Here, R ₁₀ and R ₁₁ are not limited as long as they are each independently a monovalent organic group having 1 to 20 carbon atoms. Examples of such organic groups include alkyl groups such as methyl group, ethyl group and propyl group; halogen-containing groups such as trifluoromethyl group; alkoxy groups such as methoxy group and ethoxy group; Among these, a methyl group is preferable from the viewpoint of YI in a high temperature range.
Also, j and k are not limited as long as they are independently integers from 0 to 4. Among these, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.
More specifically, 2,2'-bis(trifluoromethyl)benzidine and the like can be exemplified.
The polyimide film formed from the polyimide precursor of the first aspect of the present invention has low residual stress, little warpage, small yellowness (YI value) in a high temperature range, and high elongation.

で示される構造単位を有し、そして、重量平均分子量が３０，０００以上、３００，０００以下であるポリイミド前駆体を提供することができる。
｛式中、Ｘ_３は４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、ビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）、及びｐ－フェニレンビス（トリメリテート酸無水物）（ＴＡＨＱ）、から選択される少なくとも１種に由来する４価の基を表す。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。｝
ここでＸ_３はＯＤＰＡ，ＢＰＤＡ、ＴＡＨＱから選択される少なくとも１種に由来する４価の有機基であれば限定されないが、ＣＴＥおよびＴｇの観点から、ＢＰＤＡ、ＴＡＨＱが好ましい。
ここで、Ｒ_１～Ｒ_３はそれぞれ独立に炭素数１～２０の１価の有機基であれば限定されない。このような有機基として、メチル基、エチル基、プロピル基などのアルキル基、トリフルオロメチル基などのハロゲン含有基、メトキシ基、エトキシ基などのアルコキシ基、などが挙げられる。この中で、高温領域でのＹＩの観点から、メチル基が好ましい。
ここで、ａ、ｂ、ｃ、ｄは０～４の整数であれば限定されない。この中で、ＹＩ、残留応力の観点から０～２の整数が好ましく、高温領域でのＹＩの観点から、０が特に好ましい。
ここで、ｎは０または１である。この中で、高温領域でのＹＩの観点から、０が好ましい。 As a second aspect of this implementation,
(a2) the following general formula (10):

and a weight average molecular weight of 30,000 or more and 300,000 or less.
{wherein X ₃ is selected from 4,4′-oxydiphthalic dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA), and p-phenylene bis(trimellitate anhydride) (TAHQ), represents a tetravalent group derived from at least one of 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 0-4. }
Here, X3 is not limited as long as it is a tetravalent organic group derived from at least one selected from _ODPA , BPDA and TAHQ, but from the viewpoint of CTE and Tg, BPDA and TAHQ are preferred.
Here, R ₁ to R ₃ are not limited as long as they are each independently a monovalent organic group having 1 to 20 carbon atoms. Examples of such organic groups include alkyl groups such as methyl group, ethyl group and propyl group, halogen-containing groups such as trifluoromethyl group, and alkoxy groups such as methoxy group and ethoxy group. Among these, a methyl group is preferable from the viewpoint of YI in a high temperature range.
Here, a, b, c, and d are not limited as long as they are integers from 0 to 4. Among these, an integer of 0 to 2 is preferable from the viewpoint of YI and residual stress, and 0 is particularly preferable from the viewpoint of YI in a high temperature region.
Here, n is 0 or 1. Among these, 0 is preferable from the viewpoint of YI in the high temperature region.

As the diamine for the structure represented by the above general formula (10), the diamine used in the above general formula (6) can be used.
The weight average molecular weight (Mw) of the polyimide precursor in the second embodiment is 30,000-300,000. When the weight average molecular weight is more than 30,000, the mechanical properties such as elongation and breaking strength are excellent, the residual stress is low, and the YI is low. When the weight-average molecular weight is less than 300,000, it becomes easier to control the weight-average molecular weight during the synthesis of the polyamic acid, a resin composition having an appropriate viscosity can be obtained, and the coating properties of the resin composition are improved. Among them, the weight average molecular weight (Mw) is more preferably 35000 or more and 250000 or less, and particularly preferably 40000 or more and 230000 or less.

The content of molecules having a molecular weight of less than 1,000 in the polyimide precursor in the second aspect of the present embodiment is preferably less than 5% by mass, and less than 1% by mass, based on the total amount of the polyimide precursor. is more preferred. A polyimide film formed from a resin composition obtained using such a polyimide precursor has a low residual stress, which is preferable from the viewpoint that the haze of an inorganic film formed on the polyimide film is low.
The content of molecules having a molecular weight of less than 1,000 relative to the total amount of the polyimide precursor can be calculated from the peak area obtained by GPC measurement using a solution in which the polyimide precursor is dissolved.
The polyimide precursor of the second aspect of the present invention has excellent storage stability and excellent coatability. In addition, the polyimide film formed from the polyimide precursor of the second aspect of the present invention has low residual stress, little warpage, small yellowness index (YI value), high elongation, and high breaking strength.

The polyimide precursors in the first aspect and the second aspect include diamines represented by the above-described general formulas (6) to (9) within a range that does not impair elongation, strength, stress, yellowness, etc. Besides, other diamines can be used.
Other diamines include, for example, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 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-aminophenoxy)phenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl)hexafluoropropane, 1,4-bis(3-aminopropyldimethylsilyl)benzene, and the like. , it is preferable to use one or more selected from among these.
The content of the other diamines in the total diamine is preferably 20 mol % or less, particularly preferably 10 mol % or less.

[Production of polyimide precursor]
The polyimide precursor (polyamic acid) of the present invention is a tetracarboxylic dianhydride, a diamine (e.g., APAB) used in the structural unit represented by the above general formula (1), and the above general formula (2) It can be synthesized by subjecting a diamine (eg, 4,4'-DAS) used in the structural unit represented by a polycondensation reaction. This reaction is preferably carried out in a suitable solvent. Specifically, for example, after dissolving predetermined amounts of APAB and 4,4'-DAS in a solvent, a predetermined amount of tetracarboxylic dianhydride is added to the resulting diamine solution, followed by stirring. be done.
In the diamine component, the molar ratio between the diamine used in the structural unit represented by general formula (1) and the diamine used in the structural unit represented by general formula (2) is 99/1 to 1/99. is not limited. In the diamine component, if the diamine used in the structural unit represented by the general formula (2) is 1 mol% or more, the yellowness tends to be good, and it is used in the structural unit represented by the general formula (1). If the amount of diamine obtained is 1 mol % or more, warpage after forming an inorganic film on the obtained polyimide film tends to be favorable. The molar ratio of the diamine used in the structural unit represented by general formula (1) and the diamine used in the structural unit represented by general formula (2) is preferably 95/5 to 50/50, and 90/10. ~50/50 is more preferred. The molar ratio of the diamine used in the structural unit represented by general formula (1) and the diamine used in the structural unit represented by general formula (2) may be 80/20 to 50/50, 70/ It may be 30 to 50/50. It is preferable that the molar ratio of the diamine used in the structural unit represented by general formula (1) is greater than or equal to the molar ratio of the diamine used in the structural unit represented by general formula (2).
Further, the polyimide precursor of the second aspect of the present embodiment contains a tetracarboxylic dianhydride (eg TAHQ) and a diamine (eg APAB) used in the structural unit represented by the above general formula (6). , can be synthesized by a polycondensation reaction. This reaction is preferably carried out in a suitable solvent. Specifically, for example, after dissolving a predetermined amount of APAB in a solvent, a predetermined amount of TAHQ is added to the resulting diamine solution, followed by stirring.

When synthesizing the polyimide precursor, the ratio (molar ratio) of the tetracarboxylic dianhydride component and the diamine component is the thermal linear expansion coefficient, residual stress, elongation, and yellowness of the resulting resin film (hereinafter, YI ) from the viewpoint of controlling to a desired range, tetracarboxylic dianhydride: diamine = 100: 90 to 100: 110 (diamine 0.90 to 1.0 to 1 mole part of tetracarboxylic dianhydride 10 mol parts), and more preferably 100:95 to 100:105 (0.95 to 1.05 mol parts of diamine to 1 mol part of acid dianhydride).
In this embodiment, when synthesizing polyamic acid, which is a preferred polyimide precursor, the molecular weight is controlled by adjusting the ratio of the tetracarboxylic dianhydride component and the diamine component, and by adding a terminal blocking agent. It is possible. The closer the ratio of the acid dianhydride component to the diamine component is to 1:1, and the less the amount of endcapping agent used, the higher 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 even more preferably 99.5% by mass or more. When multiple types of acid dianhydride components or diamine components are used in combination, it is sufficient if the acid dianhydride component or diamine component as a whole has the above purity, but all types of acid dianhydrides used It is preferred that the component and the diamine component each have the purity specified above.

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, the diamine component, and the resulting polyamic acid and yield a high-molecular-weight polymer. Specific examples of such solvents include aprotic solvents, phenolic solvents, ether and glycol solvents, and the like. Specific examples of these include:
Examples of the aprotic solvent include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N-methylcaprolactam, 1,3-dimethyl imidazolidinone, tetramethylurea, the following general formula (13):

In the formula, Equamid M100 (trade name: manufactured by Idemitsu Kosan Co., Ltd.) represented by R ₁₂ = methyl group, and Equad B100 (trade name: manufactured by Idemitsu Kosan Co., Ltd.) represented by R ₁₂ = n-butyl group. amide solvent;
Lactone solvents such as γ-butyrolactone and γ-valerolactone;
Phosphorus-containing amide solvents such as hexamethylphosphoricamide and hexamethylphosphine triamide;
Sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide and sulfolane;
Ketone solvents such as cyclohexanone and methylcyclohexanone;
Tertiary amine solvents such as picoline and pyridine;
Ester solvents such as acetic acid (2-methoxy-1-methylethyl) are:
Examples of the phenolic solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2, 5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol and the like are:
Examples of the ether and glycol solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-( 2-Methoxyethoxy)ethyl]ether, tetrahydrofuran, 1,4-dioxane, etc.
Each is mentioned.

The boiling point at normal pressure of the solvent used for synthesizing the polyamic acid 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, the drying process will take a long time. On the other hand, if the boiling point of the solvent is lower than 60° C., the surface of the resin film may become rough during the drying process, air bubbles may be mixed into the resin film, and a uniform film may not be obtained.
Thus, it is preferable to use a solvent having a boiling point of preferably 170 to 270° C., more preferably a vapor pressure of 250 Pa or less at 20° C., from the viewpoint of solubility and edge repellency 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 compounds represented by the general formula (11).
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.

The (a) polyimide precursor in this embodiment preferably contains less than 5% by mass of molecules having a molecular weight of less than 1,000.
(a) The presence of molecules with a molecular weight of less than 1,000 in the polyimide precursor is considered to be related to the water content of the solvent used during synthesis. That is, it is thought that the acid anhydride groups of some acid dianhydride monomers are hydrolyzed by water to form carboxyl groups, which remain in a low-molecular state without increasing the molecular weight. Therefore, the water content of the solvent used in 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 water content of the solvent depends on the grade of the solvent used (dehydration grade, general-purpose grade, etc.), solvent container (bottle, 18L can, canister can, etc.), storage condition of the solvent (presence or absence of rare gas inclusion, etc.), and from opening to use. time (whether to use immediately after opening or after the passage of time after opening, etc.) is considered to be involved. In addition, it is considered that replacement of rare gas in the reactor before synthesis, presence or absence of circulation of rare gas during synthesis, etc. are also involved. Therefore, (a) when synthesizing a polyimide precursor, use a high-purity raw material, use a solvent with a low water content, and take measures to prevent water from the environment from entering the system before and during the reaction. recommended.

When each monomer component is dissolved in the solvent, it may be heated as necessary.
(a) The reaction temperature during synthesis of the polyimide precursor is preferably 0°C to 120°C, more preferably 40°C to 100°C, and still more preferably 60°C 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. A polyimide precursor having a uniform degree of polymerization can be obtained by setting the polymerization time to 1 hour or more, and a polyimide precursor having a high degree of polymerization can be obtained by setting the polymerization time to 100 hours or less.

In a preferred aspect of the present embodiment, (a1) polyimide precursor and (a2) polyimide precursor have the following properties.
(a) A solution obtained by dissolving a polyimide precursor in a solvent (eg, N-methyl-2-pyrrolidone) is applied to the surface of the support, and then the solution is placed in a nitrogen atmosphere (eg, with an oxygen concentration of 2,000 ppm or less). In a resin obtained by imidizing the polyimide precursor by heating (for example, 1 hour) at 300 to 550° C. (for example, 430° C.) in nitrogen), the yellowness index at a film thickness of 10 μm is 30 or less.
(a) A solution obtained by dissolving a polyimide precursor in a solvent (eg, N-methyl-2-pyrrolidone) is applied to the surface of the support, and then the solution is placed in a nitrogen atmosphere (eg, with an oxygen concentration of 2,000 ppm or less). The resin obtained by imidizing the polyimide precursor by heating (eg, 1 hour) at 300 to 550° C. (eg, 430° C.) in nitrogen) has a residual stress of 25 MPa or less.

｛一般式（１４）中、複数存在するＲ_１３は、それぞれ独立に、水素原子、炭素数１～２０の一価の脂肪族炭化水素、又は一価の芳香族基であり、
Ｘ_４は炭素数４～３２の四価の有機基であり、
Ｙは炭素数４～３２の二価の有機基である。ただし、
前記一般式（１）および前記一般式（６）に相当する構造単位を除く。｝で表される構造を有するポリイミド前駆体を更に含有してもよい。 The polyimide precursor according to the present embodiment is represented by the following general formula (14), if necessary, within a range that does not impair the desired performance of the present invention:

{In the general formula (14), each of a plurality of R ₁₃ is independently a hydrogen atom, a monovalent aliphatic hydrocarbon having 1 to 20 carbon atoms, or a monovalent aromatic group,
X ₄ is a tetravalent organic group having 4 to 32 carbon atoms,
Y is a divalent organic group having 4 to 32 carbon atoms. however,
Structural units corresponding to the general formulas (1) and (6) are excluded. } may further contain a polyimide precursor having a structure represented by .

In general formula (14), R ₁₃ is preferably a hydrogen atom. X3 is preferably a tetravalent aromatic group from the viewpoint of heat resistance _, reduction of YI value, and total light transmittance. Moreover, Y is preferably a divalent aromatic group or an alicyclic group from the viewpoint of heat resistance, reduction in YI value, and total light transmittance.

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

In a preferred aspect of the present embodiment, (a1) polyimide precursor and (a2) polyimide precursor may be partially imidized. In this case, the imidization rate is preferably 80% or less, more preferably 50% or less. This partial imidization is obtained by heating the above polyimide precursor (a) for dehydration and ring closure. This heating can be carried out at a temperature of preferably 120 to 200° C., more preferably 150 to 180° C., for preferably 15 minutes to 20 hours, more preferably 30 minutes to 10 hours.
Further, N,N-dimethylformamide dimethyl acetal or N,N-dimethylformamide diethyl acetal is added to the polyamic acid obtained by the above reaction and heated to esterify part or all of the carboxylic acid, By using it as (a) the polyimide precursor in the present embodiment, it is also possible to obtain a resin composition with improved viscosity stability during storage at room temperature. These ester-modified polyamic acids are produced by sequentially reacting the acid dianhydride component described above with one equivalent of a monohydric alcohol relative to the acid anhydride group, and a dehydration condensation agent such as thionyl chloride or dicyclohexylcarbodiimide. After that, it can also be obtained by a method of condensation reaction with a diamine component.

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

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

[(b) organic solvent]
The (b) organic solvent in the present embodiment is not particularly limited as long as it can dissolve the above-described (a) polyimide precursor and optionally used other components. As such an organic solvent (b), those mentioned above as the solvent that can be used in synthesizing the polyimide precursor (a) can be used. Preferred organic solvents are also the same as above. The (b) organic solvent in the resin composition of the present embodiment may be the same as or different from the solvent used in the synthesis of the (a) polyimide precursor.
(b) The amount of the organic solvent is preferably such that the solid content concentration of the resin composition is 3 to 50% by mass. In addition, it is preferable to adjust the composition and amount of the (b) organic solvent so that the viscosity (25° C.) of the resin composition is 500 mPa·s to 100,000 mPa·s before adding.

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝ [Other ingredients]
The resin composition of the present embodiment may further contain (c) a surfactant, (d) an alkoxysilane compound, etc., in addition to the above components (a) and (b).
The resin composition according to this embodiment includes at least one selected from the group consisting of (a) a polyimide precursor, (b) an organic solvent, (c) a surfactant and (d) an alkoxysilane compound, including.
The skeleton of the polyimide precursor is not limited to the skeletons described above in the first and second aspects. That is, the skeleton of the polyimide precursor is not particularly limited as long as it is a skeleton represented by the following general formula (1).

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. }

((c) surfactant)
By adding a surfactant to the resin composition of the present embodiment, the coating properties of the resin composition can be improved. Specifically, it is possible to prevent the occurrence of streaks in the coating film.
Examples of such surfactants include silicone-based surfactants, fluorine-based surfactants, nonionic surfactants other than these, and the like. Examples of these are:
Examples of silicone-based surfactants include organosiloxane polymers KF-640, 642, 643, KP341, X-70-092, X-70-093 (all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.), SH-28PA. , SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (manufactured by Toray Dow Corning Silicone Co., Ltd.), SILWET L-77, L-7001, FZ -2105, FZ-2120, FZ-2154, FZ-2164, FZ-2166, L-7604 (trade names, manufactured by Nihon Unicar), 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 name, manufactured by BYK-Chemie Japan), granol (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), etc.;
Examples of fluorine-based surfactants include Megafac F171, F173, R-08 (manufactured by Dainippon Ink and Chemicals, Inc., trade names), Florard FC4430, FC4432 (Sumitomo 3M Co., Ltd., trade names), and the like;
Nonionic surfactants other than these include, for example, polyoxyethylene uralyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, and the like.

Among these surfactants, silicone-based surfactants and fluorine-based surfactants are preferable from the viewpoint of coatability (streak suppression) of the resin composition. Silicone-based surfactants are preferred from the viewpoint of their influence on the rate.
(c) When using a surfactant, the amount is preferably 0.001 to 5 parts by weight, based on 100 parts by weight of the polyimide precursor (a) in the resin composition, and 0.01 to 3 parts by weight. is more preferred.

(d) Alkoxysilane compound In order for the resin film obtained from the resin composition according to the present embodiment to exhibit sufficient adhesion to the support in the manufacturing process of flexible devices and the like, the resin composition The product can contain 0.01 to 20% by mass of an alkoxysilane compound with respect to 100% by mass of (a) the polyimide precursor. When the content of the alkoxysilane compound is 0.01% by mass or more relative to 100% by mass of the polyimide precursor, good adhesion to the support can be obtained. Moreover, it is preferable that the content of the alkoxysilane compound is 20% by mass or less from the viewpoint of the storage stability of the resin composition. The content of the alkoxysilane compound is more preferably 0.02 to 15% by mass, more preferably 0.05 to 10% by mass, with respect to 100 parts by mass of the polyimide precursor, and 0.1 to 8% by mass is particularly preferred.
By using an alkoxysilane compound as an additive of the resin composition according to the present embodiment, in addition to the above-described improvement in adhesion, the coatability of the resin composition (suppression of uneven streaks) is improved, and It is possible to reduce the dependence of the YI value of the cured film on the oxygen concentration during curing.

Examples of alkoxysilane compounds include 3-ureidopropyltriethoxysilane, bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-Aminopropyltripropoxysilane, γ-Aminopropyltributoxysilane, γ-Aminoethyltriethoxysilane, γ-Aminoethyltripropoxysilane, γ-Aminoethyltributoxysilane, γ-Aminobutyltriethoxysilane, γ- Aminobutyltrimethoxysilane, γ-Aminobutyltripropoxysilane, γ-Aminobutyltributoxysilane, Phenylsilanetriol, Trimethoxyphenylsilane, Trimethoxy(p-tolyl)silane, Diphenylsilanediol, Dimethoxydiphenylsilane, Diethoxydiphenyl Examples include silane, dimethoxydi-p-tolylsilane, triphenylsilanol, and alkoxysilane compounds represented by the following structures, and the like, 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 in synthesizing the polyimide precursor and (b) the organic solvent are the same, the synthesized polyimide precursor solution can be directly used as the resin composition. Further, if necessary, in a temperature range of room temperature (25 ° C.) to 80 ° C., add one or more of (b) organic solvent and other components to the polyimide precursor, stir and mix, and then the resin composition. It can be used as an object. For this stirring and mixing, an appropriate device such as a three-one motor (manufactured by Shinto Kagaku Co., Ltd.) equipped with stirring blades, a rotation-revolution mixer, or the like can be used. Moreover, heat of 40 to 100° C. may be applied as necessary.

On the other hand, when (a) the solvent used in synthesizing the polyimide precursor is different from the (b) organic solvent, the solvent in the synthesized polyimide precursor solution is removed by, for example, reprecipitation, solvent distillation, or the like. After isolating (a) the polyimide precursor by removing it by an appropriate method, in a temperature range of room temperature to 80 ° C., (b) an organic solvent and, if necessary, other components are added, and stirred and mixed. The resin composition may be prepared by

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 portion of the polyimide precursor to such an extent that the polymer does not precipitate. It may be imidized. Here, the imidization rate can be controlled by controlling the heating temperature and heating time. By partially imidizing the polyimide precursor, the viscosity stability of the resin composition during storage at room temperature can be improved. The range of the imidization rate is preferably 5% to 70% from the viewpoint of balancing the solubility of the polyimide precursor in the resin composition solution and the storage stability of the solution.

The resin composition according to the present embodiment preferably has a water content of 3,000 ppm by mass or less.
From the viewpoint of viscosity stability during storage of the resin composition, the water content of the resin composition is more preferably 1,000 mass ppm or less, and even more preferably 500 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 more preferably 3,000 to 30,000 mPa·s at 25°C. is particularly preferred. This solution viscosity can be measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., VISCONICEHD). If the viscosity of the solution is less than 300 mPa·s, it is difficult to apply the solution during film formation.
(a) When synthesizing a polyimide precursor, even if the solution becomes highly viscous, it is possible to obtain a resin composition having a viscosity that is easy to handle by adding a solvent and stirring after the completion of the reaction. be.

The resin composition of the present embodiment has the following properties in preferred embodiments.
After coating the resin composition on the surface of the support to form a coating film, the coating film is heated at 300° C. to 550° C. in a nitrogen atmosphere (for example, in nitrogen with an oxygen concentration of 2,000 ppm or less). The resin film obtained by imidizing the polyimide precursor contained in the coating film has a yellowness index YI of 30 or less at a film thickness of 10 μm.

After coating the resin composition on the surface of the support to form a coating film, the coating film is heated at 300° C. to 550° C. in a nitrogen atmosphere (for example, in nitrogen with an oxygen concentration of 2,000 ppm or less). The resin film obtained by imidizing the polyimide precursor contained in the coating film has a residual stress of 25 MPa or less.

The resin composition according to the present embodiment can be suitably used, for example, for forming transparent substrates of display devices such as liquid crystal displays, organic electroluminescence displays, field emission displays, and electronic papers. Specifically, it can be used to form thin film transistor (TFT) substrates, color filter substrates, transparent conductive film (ITO, IndiumThinOxide) substrates, 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 easily applied to the manufacturing process of a display having a TFT element device on a colorless and transparent polyimide substrate.

<Resin film>
Another aspect of the invention provides a resin film formed from the resin precursor described above.
Moreover, still another aspect of the present invention provides a method for producing a resin film from the resin composition described above.
The resin film in this embodiment is
A step of forming a coating film by applying the above resin composition on the surface of a support (coating step);
A step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film (heating step);
a step of peeling the polyimide resin film from the support (peeling step);
characterized by comprising

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

When forming a film-like 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 (stretched polypropylene) or the like is preferred.

Examples of coating methods include coating methods such as doctor blade knife coater, air knife coater, roll coater, rotary coater, flow coater, die coater, and bar coater; coating methods such as spin coating, spray coating, and dip coating; A printing technique 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, and is preferably about 1 to 1,000 μm. The coating step may be carried out at room temperature, but 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 coating step may be followed by a drying step, or the drying step may be omitted and the next heating step may be performed directly. This drying step is performed for the purpose of removing the organic solvent. When performing the drying step, for example, a hot plate, a box-type dryer, a conveyor-type dryer, or the like can be used. The drying step is preferably carried out at 80 to 200°C, more preferably at 100 to 150°C. The duration 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 a polyimide precursor is formed on the support.
Then, a heating process is performed. The heating step is a step of removing the organic solvent remaining in the coating film in the drying step and promoting the imidization reaction of the polyimide precursor in the coating film to obtain a film made of polyimide.
This heating step can be carried out using, for example, an inert gas oven, a hot plate, a box-type dryer, a conveyor-type dryer, or the like. This step may be performed simultaneously with the drying step, or both steps may be performed sequentially.

The heating process may be carried out in an air atmosphere, but it is recommended to carry out in an inert gas atmosphere from the viewpoint of safety and the transparency and YI value of the resulting polyimide film. Examples of inert gases include nitrogen and argon.
The heating temperature may be appropriately set according to the type of the (b) organic solvent, but is preferably 250°C to 550°C, more preferably 300°C to 450°C. If the temperature is 250° C. or higher, the imidization will be sufficient, and if it is 550° C. or lower, there will be no problems such as deterioration of the transparency and heat resistance of the resulting 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 the transparency and YI value of the resulting polyimide film. Mass ppm or less is more preferable. By heating in an atmosphere with an oxygen concentration of 2,000 ppm by mass or less, the YI value of the resulting polyimide film can be made 30 or less.

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

(1) After producing a structure containing a polyimide resin film/support by the above method, a laser is irradiated from the support side of the structure to ablate the interface between the support and the polyimide resin film. , a method of stripping a polyimide resin. Types of lasers include solid-state (YAG) lasers, gas (UV excimer) lasers, and the like. It is preferable to use a spectrum with 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 of forming a release layer on a support before coating the resin composition on the support, then obtaining a structure comprising a polyimide resin film/release layer/support, and peeling off the polyimide resin film. . Examples of the release layer include a method using parylene (registered trademark, manufactured by Nippon Parylene G.K.) and tungsten oxide; and a method using a release agent such as a vegetable oil-based, silicone-based, fluorine-based, or alkyd-based release agent. (See JP-A-2010-67957, JP-A-2013-179306, etc.).
This method (2) and the laser irradiation of (1) may be used in combination.

(3) A method of obtaining a polyimide resin film by using an etchable metal substrate as a support to obtain a structure containing a polyimide resin film/support, and then etching the metal with an etchant. As the metal, for example, copper (as a specific example, electrolytic copper foil “DFF” manufactured by Mitsui Mining & Smelting Co., Ltd.), aluminum, and the like can be used. As an 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 containing 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 for separating a polyimide resin film from a

Among these peeling methods, the method (1) or (2) is suitable from the viewpoint of the front and back refractive index difference, YI value, and elongation of the obtained polyimide resin film. Method (1) is more appropriate from the viewpoint of refractive index difference.
In method (3), when copper is used as the support, the YI value of the resulting polyimide resin film tends to increase and the elongation tends to decrease. This is believed to be the effect of copper ions.

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

The resin film according to the present embodiment can have a yellowness YI of 30 or less at a film thickness of 10 μm. Also, the residual stress may be 25 MPa or less. In particular, the yellowness index YI at a film thickness of 10 μm can be 30 or less and the residual stress can be 25 MPa or less. Such properties are demonstrated, for example, by converting the resin precursor of the present disclosure to imide at 300° C. to 550° C., more preferably 350° C. to 450° C. under a nitrogen atmosphere (eg, in nitrogen with an oxygen concentration of 2,000 ppm or less). It is realized well by
The resin film according to this embodiment may further have a tensile elongation of 15% or more. The tensile elongation of the resin film may be 20% or more, and particularly 30% or more. This tensile elongation can be measured using a commercially available tensile tester using a resin film having a thickness of 10 μm as a sample.

｛式中、Ｘ_１、Ｘ_２は炭素数４～３２の４価の基を表す。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。Ｙは前記一般式（３）、（４）および（５）からなる群から選択される少なくとも１種である。ｌ、ｍはそれぞれ独立に１以上の整数を表し、０．０１≦ｌ／（ｌ＋ｍ）≦０．９９を満たす。｝で表される構造単位を有する。
ｌ／（ｌ＋ｍ）の下限は、０．０５でもよく、０．１０でもよく、０．２０でもよく、０．３０でもよく、０．４０でもよい。
ｌ／（ｌ＋ｍ）の上限は、０．９５でもよく、０．９０でもよく、０．８０でもよく、０．７０でもよく、０．６０でもよい。
前述のように、好ましくは、残留応力が２５ＭＰａ以下であり、ＹＩが３０以下であり、ガラス転移温度が４００℃以上であり、伸度が１５％以上であり、そして破断強度が２５０ＭＰａ以上である。 The resin film according to the present embodiment is a film made of polyimide obtained by thermally imidizing (a1) the polyimide precursor contained in the resin composition. Therefore, the following general formula (11):

{In the formula, X _{1 and} X ₂ represent a tetravalent group having 4 to 32 carbon atoms. 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 0-4. Y is at least one selected from the group consisting of general formulas (3), (4) and (5). l and m each independently represent an integer of 1 or more and satisfy 0.01≦l/(l+m)≦0.99. } has a structural unit represented by
The lower limit of l/(l+m) may be 0.05, 0.10, 0.20, 0.30, or 0.40.
The upper limit of l/(l+m) may be 0.95, 0.90, 0.80, 0.70, or 0.60.
As described above, it preferably has a residual stress of 25 MPa or less, a YI of 30 or less, a glass transition temperature of 400° C. or more, an elongation of 15% or more, and a breaking strength of 250 MPa or more. .

｛式中、Ｘ_３は４，４’－オキシジフタル酸二無水物（ＯＤＰＡ）、ビフェニルテトラカルボン酸二無水物（ＢＰＤＡ）、及びｐ－フェニレンビス（トリメリテート酸無水物）（ＴＡＨＱ）、から選択される少なくとも１種に由来する４価の基を表す。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。｝で表される構造単位を有し、伸度が１５％以上である、樹脂フィルムであり、好ましくは残留応力が２５ＭＰａ以下であり、ＹＩが３０以下であり、ガラス転移温度が４００℃以上であり、そして破断強度が２５０ＭＰａ以上である。 A second aspect is a film made of polyimide obtained by thermally imidizing (a2) the polyimide precursor contained in the resin composition. Therefore, the following general formula (12):

{wherein X ₃ is selected from 4,4′-oxydiphthalic dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA), and p-phenylene bis(trimellitate anhydride) (TAHQ), represents a tetravalent group derived from at least one of 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 0-4. }, has an elongation of 15% or more, preferably has a residual stress of 25 MPa or less, a YI of 30 or less, and a glass transition temperature of 400 ° C. or more. and has a breaking strength of 250 MPa or more.

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

This laminate can be suitably used, for example, in the production of flexible devices.
A more detailed description is as follows.
When forming a flexible display, a glass substrate is used as a support, a flexible substrate is formed thereon, and TFTs and the like are further formed thereon. The process of forming a TFT or the like on a flexible substrate is typically performed at a wide temperature range of 150-650.degree. However, in order to realize the performance desired in reality, TFT-IGZO (InGaZnO) oxide semiconductor or TFT (a-Si-TFT, poly -Si-TFT).
On the other hand, due to these thermal histories, the physical properties of the polyimide film (especially yellowness and elongation) tend to decrease. However, the polyimide film obtained from the polyimide precursor according to the present invention exhibits extremely little decrease in yellowness and elongation even in a high temperature range of 400° C. or higher, and can be used satisfactorily in this range.

｛式中、Ｘ_１は炭素数４～３２の４価の基を表す。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。｝
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Ｓｉ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ＬＴＰＳ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。 Furthermore, the present embodiment can provide a laminate including a polyimide film layer containing polyimide represented by the following general formula (13) and a LTPS (low temperature polysilicon TFT) layer.

{In the formula, X ₁ represents a tetravalent group having 4 to 32 carbon atoms. 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 0-4. }
As a method for producing the laminate, an amorphous Si layer is formed after producing a laminate containing the above support and a polyimide resin film formed from the above resin composition on the surface of the support. The LTPS layer can be formed by performing dehydrogenation annealing at 400 to 450° C. for about 0.5 to 3 hours, followed by crystallization with an excimer laser or the like. Then, the laminate can be obtained by separating the glass and the polyimide film by laser separation or the like.

A laminate including a polyimide film layer containing polyimide represented by general formula (13) and an LTPS (low-temperature polysilicon TFT) layer has less peeling and swelling after a heat cycle test, and less substrate warpage.
In addition, if the residual stress generated in the flexible substrate and the polyimide resin film is high, when the laminated body composed of both expands in the TFT process at a high temperature and then shrinks when cooled to room temperature, the glass substrate warps and breaks, and the glass of the flexible substrate Problems such as delamination from the substrate may occur. Generally, since the coefficient of thermal expansion of a glass substrate is smaller than that of resin, residual stress is generated between the glass substrate and the flexible substrate. As described above, the resin film according to the present embodiment can reduce the residual stress generated between itself and the glass substrate to 25 MPa or less, so that it can be suitably used for forming a flexible display.

Furthermore, the polyimide film according to the present embodiment can have a yellowness index YI of 30 or less and a tensile elongation of 15% or more at a film thickness of 10 μm. As a result, the resin film according to the present embodiment has excellent breaking strength when handling flexible substrates, and therefore can improve the yield when manufacturing flexible displays.

In another embodiment, the yellowness index at a film thickness of 10 microns after heating at 400 ° C. or higher is 20 or less, and the absorbance at 308 nm at a film thickness of 0.1 micron is 0.6 or more and 2.0 or less. It is possible to provide a polyimide film having an elongation of 15% or more.
By setting the YI to 20 or less, a flexible substrate can be produced without degrading the image quality when used as a display.
It is more preferably 18 or less, and particularly preferably 16 or less.
When the absorbance at 308 nm is 0.6 or more and 2.0 or less and the elongation is 15% or more when the film thickness is 0.1 μm, for example, the polyimide film can be easily peeled off from the glass substrate with a laser. From the viewpoint of suppressing ash after laser peeling, it is preferably 0.6 or more and 1.5 or less and the elongation is 20% or more. 20% or more is particularly preferred.
Although there is no particular upper limit for elongation, it may be 80% or less, 70% or less, 60% or less, 50% or less, or 40% or less.
In addition, the polyimide film may be burned by the laser beam during the laser peeling, and the unburned residue is ash.

Accordingly, another aspect of the invention provides a display substrate.
Yet another aspect of the present invention provides a method of manufacturing the above display substrate.
The manufacturing method of the display substrate in this embodiment includes:
A step of forming a coating film by applying the above resin composition onto the surface of a support (coating step);
A step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film (heating step);
A step of forming an element or circuit on the polyimide resin film (element/circuit forming step);
and a step of peeling the polyimide resin film having the elements or circuits formed thereon from the support (peeling step).

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

The resin film according to the present embodiment, which satisfies the above physical properties, is suitable for applications where the use is limited due to the yellow color of existing polyimide films, particularly for applications such as colorless transparent substrates for flexible displays and protective films for color filters. be. Furthermore, for example, protective film, light scattering sheet and coating film in TFT-LCD etc. (for example, TFT-LCD interlayer, gate insulating film, liquid crystal alignment film, etc.), ITO substrate for touch panel, resin substrate for smartphone cover glass substitute It can also be used in fields where colorless transparency and low birefringence are required, such as. By applying the polyimide according to this embodiment as a liquid crystal alignment film, it becomes possible to manufacture a TFT-LCD with a high aperture ratio and a high contrast ratio.

The polyimide precursor according to the present embodiment, the resin film and laminate produced using the resin precursor can be applied, for example, as a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, etc. In addition, it can be used for flexible devices. In manufacturing, it can be suitably used especially as a substrate. Flexible devices to which the resin film and laminate according to the present embodiment can be applied include, for example, flexible displays, flexible solar cells, flexible touch panel electrode substrates, flexible lighting, and flexible batteries.

The present invention will be described in more detail below 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>
Weight average molecular weight (Mw) and number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) under the following conditions.
As a solvent, N,N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd., for high-performance liquid chromatograph, 24.8 mmol / L lithium bromide monohydrate (manufactured by Wako Pure Chemical Industries, purity 99.0) immediately before measurement. 5%) and 63.2 mmol/L of phosphoric acid (manufactured by Wako Pure Chemical Industries, Ltd., for high-performance liquid chromatograph) were added and dissolved) were used. A calibration curve for calculating the weight average molecular weight was created using standard polystyrene (manufactured by Tosoh Corporation).

Column: Shodex KD-806M (manufactured by Showa Denko)
Flow rate: 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 spectrophotometer, manufactured by JASCO)

<Evaluation of the content of molecules with a molecular weight of less than 1,000 (low molecular weight content)>
The content of molecules with a molecular weight of less than 1,000 in the resin is determined using the GPC measurement results obtained above, and the ratio (percentage ) was calculated as

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

<Evaluation of Viscosity Stability of Resin Composition>
For each of the resin compositions prepared in Examples and Comparative Examples,
A sample left at room temperature for 3 days after preparation is used as a sample after preparation, and the viscosity is measured at 23 ° C.;
After that, the sample was allowed to stand at room temperature for 2 weeks, and the viscosity at 23° C. was measured again using the sample after 2 weeks. 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 viscosity change at room temperature for 2 weeks was calculated according to the following formula.
Room temperature 2-week viscosity change rate (%) = [(viscosity of sample after 2 weeks) - (viscosity of sample after preparation)] / (viscosity of sample after preparation) x 100
The 2-week viscosity change rate 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 "good")
×: Viscosity change rate is more than 10% (storage stability "bad")

<Evaluation of varnish applicability>
The resin composition prepared in each of Examples and Comparative Examples was coated on a non-alkali glass substrate (size 37×47 mm, thickness 0.7 mm) using a bar coater so that the film thickness after curing was 15 μm. After that, it was pre-baked 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 μm or less (applicability “excellent”)
○: Surface step is more than 0.1 and 0.5 μm or less (applicability “good”)
×: Surface level difference is more than 0.5 μm (applicability “bad”)

<Evaluation of residual stress>
Each resin composition was applied by a spin coater onto a 6-inch silicon wafer having a thickness of 625 μm±25 μm and pre-baked at 100° C. for 7 minutes. After that, using a vertical curing furnace (manufactured by Koyo Lindbergh, model name VF-2000B), the oxygen concentration in the chamber is adjusted to 10 mass ppm or less, and heat curing is performed at 430 ° C. for 1 hour ( Curing treatment) was performed, and a silicon wafer with a polyimide resin film having a film thickness of 10 μm after curing was produced.
The amount of warpage of this wafer was measured using a residual stress measuring device (manufactured by Tencor, model name: FLX-2320) to evaluate the residual stress generated between the silicon wafer and the resin film.
◎: Residual stress is more than -5 and 15 MPa or less (residual stress evaluation “excellent”)
○: Residual stress is more than 15 and 25 MPa or less (residual stress evaluation “good”)
×: Residual stress is over 25 MPa (residual stress evaluation “bad”)

<Warpage evaluation of polyimide resin film with inorganic film formed>
The resin composition prepared in each of Examples and Comparative Examples was spin-coated onto a 6-inch silicon wafer substrate having an aluminum deposition layer on its surface so that the film thickness after curing was 10 μm, and the coating was heated at 100° C. for 7 minutes. Prebaked. After that, using a vertical curing furnace (manufactured by Koyo Lindbergh Co., Ltd., model name VF-2000B), the oxygen concentration in the chamber is adjusted to 10 ppm by mass or less, and heat curing is performed at 430 ° C. for 1 hour. A wafer on which a polyimide resin film was formed was produced. Using this wafer, a silicon nitride (SiNx) film, which is an inorganic film, is formed with a thickness of 100 nm on the polyimide resin film by the CVD method at 350° C., and an inorganic film/polyimide resin laminated wafer is formed. got

The laminate wafer obtained above was immersed in a dilute hydrochloric acid aqueous solution, and the two layers of the inorganic film and the polyimide film were integrally separated from the wafer to obtain a polyimide film sample having an inorganic film formed on the surface. Using this sample, the warpage of the polyimide resin film was evaluated.
◎: No warpage (warpage "excellent")
○: Slightly warped (warpage "good")
×: The film is curled due to warpage (warpage "bad")

<Evaluation of yellowness index (YI value)>
Wafers (with no inorganic film formed thereon) were produced in the same manner as in <Evaluation of warpage of polyimide resin film with inorganic film formed thereon>. A resin film was obtained by immersing the wafer in a dilute hydrochloric acid aqueous solution and peeling off the polyimide resin film.
The YI value (converted to a film thickness of 10 μm) was measured for the obtained polyimide resin film using a D65 light source (Spectrophotometer: SE600) manufactured by Nippon Denshoku Industries Co., Ltd.

<Evaluation of elongation and breaking strength>
Wafers (with no inorganic film formed thereon) were produced in the same manner as in <Evaluation of Warpage of Polyimide Resin Film with Inorganic Film Formed> above. Using a dicing saw (DAD 3350, manufactured by Disco Co., Ltd.), the polyimide resin film of the wafer was cut with a width of 3 mm, then immersed in a dilute hydrochloric acid solution overnight to peel off the resin film piece, and dried. This was cut to a length of 50 mm and used as a sample.
The elongation and breaking strength of the above sample were measured using TENSILON (UTM-II-20 manufactured by Orientec) at a test speed of 40 mm/min and an initial load of 0.5 fs.
<Measurement of absorbance at 308 nm of polyimide resin film>
Each of the above varnishes was spin-coated on a quartz glass substrate and heated at 430° C. for 1 hour in a nitrogen atmosphere to obtain a polyimide resin film with a thickness of 0.1 μm. Absorbance at 308 nm was measured for these polyimide films using UV-1600 (manufactured by Shimadzu Corporation).

[Example 1]
96 g of N-methyl-2-pyrrolidone (NMP) was placed in a nitrogen-substituted 500 ml separable flask, and 17.71 g (77.6 mmol) of 4-aminophenyl-4-aminobenzoate (APAB) and 4,4'- 4.82 g (19.4 mmol) of diaminodiphenylsulfone (DAS) was added and stirred to dissolve APAB and DAS. After that, 29.42 g (100 mmol) of biphenyl-3,3′,4,4′-tetracarboxylic dianhydride (BPDA) was added, and a polymerization reaction was carried out with stirring at 80° C. for 3 hours under nitrogen flow. Thereafter, the mixture was cooled to room temperature, and the NMP was added to adjust the solution viscosity to 51,000 mPa·s, thereby obtaining an NMP solution of polyamic acid (hereinafter also referred to as varnish) P-1. The weight average molecular weight (Mw) of the obtained polyamic acid was 65,000.

[Examples 2 to 21 and Comparative Examples 1 to 5]
In Example 1 above, the amount (molar ratio) of raw materials charged, the type of solvent used, the polymerization temperature, and the polymerization time were changed as shown in Table 1, respectively, in the same manner as in Example 1. , varnishes P-2 to P-26 were obtained.
Table 1 also shows the weight average molecular weight (Mw) of the polyamic acid contained in each varnish.

The abbreviations of each component in Table 1 have the following meanings.
BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride PMDA: pyromellitic dianhydride TAHQ: p-phenylene bis(trimellitate anhydride)
APAB: 4-aminophenyl-4-aminobenzoate ATAB: 2-methyl-4-aminophenyl-4-aminobenzoate BABB: [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate BAFL: 9,9- Bis(aminophenyl)fluorene BFAF: 9,9-bis(4-amino-3-fluorophenyl)fluorene TFMB: 2,2'-bis(trifluoromethyl)benzidine DAS: 4,4'-diaminodiphenylsulfone NMP: N-methyl-2-pyrrolidone DMF: N,N-dimethylformamide DMAc: N,N-dimethylacetamide

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

As is clear from Tables 1 and 2, the polyimide films obtained in Comparative Examples 1 and 2, which contain only the structural unit represented by the general formula (1), are fragile and cannot be evaluated for physical properties such as elongation. I didn't. Also, the residual stress was high. In addition, the polyimide film obtained in Comparative Example 3, which contains only the structural unit represented by general formula (2), had high residual stress, warped after forming the inorganic film, and had low elongation.
On the other hand, the polyimide film obtained from Examples 1 to 21, containing the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) at a molar ratio of 99/1 to 1/99. had a low yellowness index of 20 or less, a low residual stress of 25 MPa or less, and a high elongation of 20% or more. Further, warping after forming the inorganic film did not occur or, if it occurred, it was very slight.
From the results in Table 2 above, it was confirmed that the polyimide resin film obtained from the resin composition according to the present invention is a resin film having a low degree of yellowness, a low residual stress, and excellent mechanical properties.
Specifically, in the present invention, a resin film having a residual stress of 25 MPa or less, a yellowness index YI of 30 or less, and an elongation of 15% or more can be obtained.

[Example 22]
N-methyl-2-pyrrolidone (NMP) (water content: 250 mass ppm) immediately after opening the 18L can was added to a 500ml separable flask that was purged with nitrogen, and an amount corresponding to a solid content of 17wt% was added, and 4-aminophenyl was added. 5.71 g (25.0 mmol) of -4-aminobenzoate (APAB, purity 99.5%, manufactured by Nihon Junryo Yakuhin Co., Ltd.) was added and stirred to dissolve APAB. After that, 7.36 g (25.0 mmol) of biphenyl-3,3′,4,4′-tetracarboxylic dianhydride (BPDA, purity 99.5%, manufactured by Manac Co., Ltd.) was added, and the mixture was stirred at 80°C under nitrogen flow. The polymerization reaction was carried out with stirring at ℃ for 3 hours. Thereafter, the mixture was cooled to room temperature, and the NMP was added to adjust the solution viscosity to 51,000 mPa·s, thereby obtaining an NMP solution of polyamic acid (hereinafter also referred to as varnish) P-27. The polyamic acid obtained had a weight average molecular weight (Mw) of 128,000 and a content of molecules having a molecular weight of less than 1,000 of 0.01% by mass.

[Examples 23-33 and Comparative Examples 6-11]
In the above Example 22, in the same manner as in Synthesis Example 1, except that the type of raw material, the amount of raw material charged, the type of solvent used, the polymerization temperature, and the polymerization time were changed as shown in Table 3, Varnishes P-28 to P-44 were obtained.
Table 3 also shows the weight average molecular weight (Mw) of the polyamic acid contained in each varnish.

The abbreviations of each component in Table 3 have the following meanings.
BPDA: biphenyltetracarboxylic dianhydride, purity 99.5%, manufactured by Mitsubishi Chemical Corporation TAHQ: p-phenylene bis (trimellitate anhydride), purity 99.5%, manufactured by Manac Corporation PMDA: dipyromellitic acid Anhydrous APAB: 4-aminophenyl-4-aminobenzoate, 99.5% purity
4,3-APAB: 4-aminophenyl-3-aminobenzoate, 99.5% pure
ATAB: 2-methyl-4-aminophenyl-4-aminobenzoate BABB: [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate NMP1: 18L can immediately after opening, water content 250ppm
NMP2: A product in a 500 ml bottle left for one month after opening, moisture content 3,070 ppm
DMF: 500ml bottle after opening, water content 3510ppm
DMAc: 500ml bottle after opening, water content 3430ppm

[Examples 22-33 and Comparative Examples 6-11]
The varnishes P-27 to P-44 obtained in the above examples and comparative examples were used as resin compositions as they were, and were evaluated according to the method described above. The evaluation results are shown in Table 4.

As is clear from Tables 3 and 4, the weight average molecular weight of the polyimide precursor (varnish) is 3,000 or less Comparative Example 6 (P-39), Comparative Example 7 (P-40), Comparative Example 8 (P -41), Comparative Example 10 (P-43) and Comparative Example 11 (P-44) had large residual stress and large warpage. In addition, the yellowness was large, and the elongation and breaking strength were also small. In particular, in Comparative Examples 10 and 11, which contained a large amount of water, the films were very fragile.
On the other hand, in Comparative Example 9 (P-42) in which the weight average molecular weight of the polyimide precursor was 30,0000 or more, the residual stress and warpage were small, the yellowness was low, the elongation and breaking strength were large, but the applicability was poor. It's gotten worse.
On the other hand, in Examples 22 to 33 using polyimide precursors P-27 to P-38 having a weight average molecular weight of 30,000 or more and 300,000 or less, the residual stress was low, the warpage was small, and the yellow color was obtained. Excellent results were obtained in all of the properties of low modulus, high elongation and breaking strength.

From the results in Table 4 above, it was confirmed that the polyimide resin film obtained from the resin composition according to the present invention is a resin film having a low degree of yellowness, a low residual stress, and excellent mechanical properties.
Specifically, in the present invention, the residual stress is 25 MPa or less, the yellowness index YI is 20 or less, the glass transition temperature is 400 ° C. or more, the elongation is 15% or more, and the breaking strength is 250 MPa The above resin film is obtained.

In Examples 34 to 45 shown below, experiments were conducted on the effect of adding at least one selected from the group consisting of surfactants and alkoxysilane compounds to the resin composition.
[Example 34]
First, using the varnish P-27 obtained in Example 22 as it is as a resin composition, coating streaks were evaluated by the following procedure.
<Evaluation of coating streaks (coating properties)>
The above resin composition was coated on a non-alkali glass substrate (size 37×47 mm, thickness 0.7 mm) using a bar coater so that the film thickness after curing was 15 μm. After coating, the film was allowed to stand at room temperature for 10 minutes, and then the resulting coating film was visually checked for coating streaks. The same resin composition was applied three times, the number of coating streaks on each coating film was examined, and the average value was used for evaluation according to the following criteria.
◎: 0 continuous coating streaks with a width of 1 mm or more and a length of 1 mm or more (evaluation of coating streaks “excellent”)
○: 1 or 2 coating streaks (evaluation of coating streaks “good”)
△: 3 to 5 coating streaks (evaluation of coating streaks “acceptable”)
The evaluation results are shown in Table 5.

[Examples 35-45]
After adding surfactants or alkoxysilane compounds of the types and amounts shown in Table 5 as additional additives to the varnish P-27 obtained in Example 22, filtering through a 0.1 μm filter, , to prepare a resin composition.
Coating streaks were evaluated in the same manner as in Example 34 using the above resin composition. Table 5 shows the results.

The abbreviations of each component in Table 5 have the following meanings. The amount of these components used in Table 5 is the amount (used amount) per 100 parts by mass of the polyimide precursor contained in the varnish. In Examples 39 and 45, surfactant 1 and alkoxysilane compound 1 were used in combination.
Surfactant 1: DBE-821, product name, silicone surfactant, manufactured by Gelest Surfactant 2: Megafac F171, product name, fluorine-based surfactant, manufactured by DIC Alkoxysilane compound 1: the following general formula (AS -1) compound represented by alkoxysilane compound 2: compound represented by the following general formula (AS-2)

As is clear from Table 5, in Examples 35 to 39 containing a surfactant or an alkoxysilane compound, and Examples 41 to 45, the occurrence of coating streaks compared to Examples 34 and 40 not containing. It was found that a polyimide resin film having excellent surface smoothness was obtained.

[Example 46]
Varnish P-27 was coated on a non-alkali glass substrate (size 37×47 mm, thickness 0.7 mm) using a bar coater so that the film thickness after curing was 10 μm, and then prebaked at 140° C. for 60 minutes. Subsequently, using a vertical curing furnace (manufactured by Koyo Lindbergh, model name VF-2000B), the oxygen concentration in the chamber is adjusted to 10 ppm by mass or less, and heat curing is performed at 430 ° C. for 1 hour. A glass substrate having a polyimide resin film formed thereon was produced. An amorphous silicon layer was formed on this polyimide film, subjected to dehydrogenation annealing at 430° C. for 1 hour, and then irradiated with an excimer laser to form an LTPS layer. The glass substrate was peeled off with an excimer laser (wavelength: 308 nm, repetition frequency: 300 Hz) to obtain a laminate containing a polyimide film and an LTPS layer.
This laminate had no warpage and had a yellowness of 20 or less.

[Example 47]
A laminate was obtained in the same manner as in Example 46, except that varnish P-1 was used. This laminate had no warp and had a yellowness of 20 or less.

[Comparative Example 12]
A laminate was obtained in the same manner as in Example 46, except that varnish P-24 was used. This laminate had a large amount of warpage, and the polyimide film was partially cracked.

[Synthesis example]
2.24 g (9.8 mmol) of APAB, 16.14 g of NMP and 50 g of toluene were placed in a separable flask equipped with a Dean-Stark apparatus and a reflux vessel under a nitrogen atmosphere, and APAB was dissolved with stirring. 2.24 g (10.0 mmol) of H-PMDA was added thereto, and the mixture was refluxed at 180° C. for 2 hours, and then the azeotropic solvent toluene was removed over 3 hours. The contents of the flask were cooled to 40° C., and it was confirmed by IR that the absorption (C═O) around 1,650 cm ⁻¹ originating from the amide bond had disappeared. Then, add 8.95 g (39.2 mmol) of APAB, 121.6 g of NMP, 6.54 g (30.0 mmol) of PMDA and 4.44 g (10.0 mmol) of 6FDA and stir at 80° C. for 4 hours. A polyimide-polyamic acid polymer varnish was obtained (P-45). The weight average molecular weight (Mw) of the obtained polyimide-polyamic acid polymer was 82,000.

[Examples 48 to 53, Comparative Example 13]
An organic EL substrate as shown in FIG. 1 was produced.
Polyimide precursor varnishes (P-1, P-11, P-20, P-22, P-27, P-33, P-45) were coated on a mother glass substrate (0.7 mm thick) using a bar coater. was applied so that the film thickness after curing was 10 μm, and then prebaked at 140° C. for 60 minutes. Subsequently, using a vertical curing furnace (manufactured by Koyo Lindbergh, model name VF-2000B), the oxygen concentration in the chamber is adjusted to 10 ppm by mass or less, and heat curing is performed at 430 ° C. for 1 hour. A glass substrate having a polyimide resin film formed thereon was produced.
Subsequently, a SiN layer having a thickness of 100 nm was formed by a CVD (Chemical Vapor Deposition) method.

Subsequently, a film of titanium was formed by a sputtering method, and then patterned by a photolithography method to form a scanning signal line.
Next, a SiN layer having a thickness of 100 nm was formed by a CVD method over the entire glass substrate on which the scanning signal lines were formed. (The process up to this point is referred to as a lower substrate 2a.)
Subsequently, an amorphous silicon layer 256 was formed on the lower substrate 2a, subjected to dehydrogenation annealing 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 spin coating, and exposed and developed by photolithography to form 258 having a plurality of contact holes 257 therein. A part of each LTPS 256 is exposed by the contact hole 257 .
Next, an ITO film is formed by sputtering on the entire surface of the lower substrate 2a on which the interlayer insulating film 258 is formed, exposed and developed by photolithography, patterned by etching, and paired with each LTPS. A lower electrode 259 was formed as follows.
In each contact hole 257, the lower electrode 252 penetrating the interlayer insulating film 258 and the LTPS 256 were electrically connected.
Next, after forming the partition 251 , a hole transport layer 253 and a light emitting layer 254 were formed in each space partitioned by the partition 251 . An upper electrode 255 was formed to cover the light emitting layer 254 and the partition wall 251 . An organic EL substrate 25 was produced by the above steps.
Next, the glass substrate, the polyimide film of the present embodiment, and the SiN layer formed in this order are coated on the periphery of the sealing substrate 2b with an ultraviolet curable resin, and the sealing substrate 2b and the organic EL substrate are separated in an argon gas atmosphere. The organic EL element was encapsulated by bonding. Thereby, 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 sealing substrate 2b side of the laminate thus formed, and peeling was performed with the minimum energy necessary for peeling the entire surface. .
With respect to the laminate of No. 2, the presence or absence of substrate warpage after peeling, a lighting test, and a cloudiness evaluation of the laminate were evaluated. A heat cycle test was also conducted. Table 6 shows the results.
<Board warpage>
◎: No warp ○: Slightly warped △: Curled due to warping <Lighting test>
○: Lighted ×: Not lighted <Laminate cloudiness evaluation>
After forming the laminate, the case where the entire device was transparent was rated as ◯, the case where the device was slightly cloudy was rated as Δ, and the case where the device was cloudy was rated as x.
<Heat cycle test>
Using a heat cycle tester manufactured by Espec, 1000 cycles of −5° C. and 60° C. were tested for 30 minutes each (movement time between tanks was 1 minute), and then the external appearance was observed.
A sample with no peeling or blistering was rated ◯, a sample with a small amount of peeling or blistering after the test was rated Δ, and a sample with peeling or blistering over the entire surface after the test was rated x.

[Examples 54 to 58, Comparative Example 14]
Except that LTPS was changed to IGZO when manufacturing the above laminate using polyimide precursor varnish (P-1, P-11, P-20, P-22, P-27, P-33, P-45) produced a laminate and conducted the above tests. Table 7 shows the results.

[Examples 59 to 63, Comparative Example 15]
Polyimide precursor varnishes (P-1, P-11, P-20, P-27, P-33, P-45), the ash ⁽ ash) was evaluated. A case where no ash was generated was rated as ◯, a case where a little ash was observed at the edges was rated as Δ, and a case where ash was observed over the entire surface was rated as x. Table 8 shows the results.

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

The resin film formed from the polyimide precursor of the present invention can be applied, for example, to semiconductor insulating films, TFT-LCD insulating films, electrode protective films, etc. In addition, in the production of flexible displays, substrates for touch panel ITO electrodes, etc., especially substrates It can be suitably used as.

Claims (9)

(a2) the following general formula (10):

{wherein X ₃ is from the group consisting of 4,4′-oxydiphthalic dianhydride (ODPA), biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenebis(trimellitate anhydride) (TAHQ); represents a tetravalent group derived from at least one selected type; 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 0-4. }
has a structural unit represented by
A polyimide precursor further comprising at least one selected from the group consisting of (c) a surfactant and (d) an alkoxysilane compound.
However, in the polyimide precursor, those having a structural unit represented by the following formula are excluded.

(In the formula, Ar represents a tetravalent aromatic group obtained by removing the carboxyl group from an aromatic tetracarboxylic acid, and R ₅ and R ₆ independently have a radically polymerizable unsaturated bond with 2 to 6 carbon atoms. Indicates a monovalent organic group.) 2. The polyimide precursor according to claim 1, wherein n in the general formula (10) is 0. 3. Polyimide precursor according to claim 1 or 2, wherein molecules with a molecular weight of less than 1000 are less than 5% by weight relative to the total weight of the polyimide precursor. The polyimide precursor according to any one of claims 1 to 3, which can produce a resin film that satisfies at least one of the following (1) to (3).
(1) The yellowness index YI at a film thickness of 10 μm is more than 0 and 30 or less.
(2) Residual stress is more than 0 and 25 MPa or less.
(3) Tensile elongation at a film thickness of 10 μm is 15% or more. A resin composition comprising the polyimide precursor according to any one of claims 1 to 4 and (b) an organic solvent. A step of forming a coating film by applying the resin composition according to claim 5 on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
a step of peeling the polyimide resin film from the support;
A method for producing a resin film, comprising: 7. The method for producing a resin film according to claim 6, wherein a step of irradiating a laser from the side of the support is performed prior to the step of peeling the polyimide resin film from the support. A step of forming a coating film by applying the resin composition according to claim 5 on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
A method for manufacturing a laminate, comprising: A step of forming a coating film by applying the resin composition according to claim 5 on the surface of a support;
a step of imidizing the polyimide precursor contained in the coating film by heating the support and the coating film to form a polyimide resin film;
forming an element or circuit on the polyimide resin film;
a step of peeling the polyimide resin film on which the element or circuit is formed from the support;
A method of manufacturing a display substrate, comprising:

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