JPWO2019142866A1 - Polyimide precursor resin composition - Google Patents

Abstract

The following formula (1): {In the formula, R1 independently represents a divalent organic group when there are a plurality of them, R2 represents a tetravalent organic group independently when there are a plurality of them, and n is a positive integer. is there. } A resin composition containing a polyimide precursor having a structure represented by} and a solvent, wherein the polyimide precursor has a weight average molecular weight of 110,000 to 250,000 and is a solid of the resin composition. A resin composition having a content content of 10 to 25% by mass is provided.

Description

The present invention relates to a resin composition containing a polyimide precursor and a polyimide film. The present invention also relates to flexible devices (eg, flexible displays) and laminates and methods of manufacturing them.

The polyimide resin is an insoluble or insoluble superheat-resistant resin, and has excellent heat-resistant properties (for example, heat-resistant oxidation resistance), radiation resistance, low-temperature resistance, chemical resistance, and the like. For this reason, polyimide resins are used in a wide range of fields including electronic materials. Examples of applications of the polyimide resin in the field of electronic materials include an insulating coating material, an insulating film, a semiconductor, an electrode protective film of a thin film transistor liquid crystal display (TFT-LCD), and the like. Recently, the adoption of a flexible substrate that utilizes its lightness and flexibility has been studied in place of the glass substrate that has been conventionally used in the field of display materials.

For example, Patent Document 1 describes a resin precursor (weight average molecular weight of 30,000 to 90,000) polymerized from bis (diaminodiphenyl) sulfone (hereinafter, also referred to as DAS) and having a siloxane unit, and the precursor is cured. The polyimide thus obtained has low residual stress generated between it and a support such as glass, has excellent chemical resistance, and has an effect on the yellowness (YI) value and total light transmittance due to the oxygen concentration during the curing process. It is stated that is small. Further, Patent Document 2 describes a resin composition characterized by containing a polyimide precursor having a specific absorbance and an alkoxysilane compound having a specific absorbance, and obtained by curing the resin composition. It is described that the resin to be used has both sufficient adhesiveness to the support and peelability by laser peeling or the like.

International Publication No. 2014/148441 International Publication No. 2016/167296

When applying a transparent polyimide resin to a flexible substrate, a resin composition containing a polyimide precursor is applied onto a substrate such as glass to form a coating film, which is then heat-dried, and then the polyimide precursor is further applied. Is imidized to form a polyimide film, and if necessary, a device is formed on the film, and then the film is peeled off from a glass substrate or the like as a support to obtain a target product.

In recent years, with the increase in size of displays and the like, which are used for flexible substrates, a slit coater may be used when a composition containing a polyimide precursor is applied to a substrate such as glass. When the composition is applied with a slit coater to form a coating film, there is a coater gap (a set value that defines the distance between the glass substrate and the slit nozzle) as a parameter that affects the coating film, but the coater gap is If it is small, the nozzle may come into contact with the substrate when the flatness of the glass substrate is poor, and the slit nozzle may be damaged. In particular, with the recent increase in size of displays and the like, it has become necessary to sufficiently increase this coater gap.
Further, when a polyimide film is used as a screen material for a flexible display or the like, the wavelength of visible light is about 380 nm to about 700 nm. Therefore, in order to obtain good optical performance, particularly high film thickness uniformity is required. Be done.

When the present inventors evaluated the coating of the slit coat using a polyimide precursor having the same molecular weight and skeleton as those described in Patent Documents 1 and 2, the above characteristics were insufficient. I found it. Therefore, one aspect of the present invention is to provide a polyimide precursor-containing resin composition which is excellent in coating properties of a slit coat and also excellent in mechanical properties and optical properties required for applications such as flexible substrates. ..

｛式中、Ｒ₁は、複数ある場合それぞれ独立に２価の有機基を示し、Ｒ₂は、複数ある場合それぞれ独立に４価の有機基を示し、ｎは正の整数である。｝で表される構造を有するポリイミド前駆体と、溶媒と、を含む樹脂組成物であって、
前記ポリイミド前駆体の重量平均分子量が１１０，０００〜２５０，０００であり、
前記樹脂組成物の固形分含有量が１０〜２５質量％である、樹脂組成物。
［２］ 前記樹脂組成物の粘度を温調機付粘度計で２３℃にて測定したときの、下記式で表されるせん断速度依存性（ＴＩ）が、０．９〜１．１である、上記態様１に記載の樹脂組成物。
ＴＩ＝ηａ／ηｂ
｛式中、ηａ（ｍＰａ・ｓ）は樹脂組成物の測定回転速度ａ（ｒｐｍ）における粘度であり、ηｂ（ｍＰａ・ｓ）は樹脂組成物の測定回転速度ｂ（ｒｐｍ）における粘度であり、ただしａ＊１０＝ｂである。｝
［３］ 前記樹脂組成物は、スリットコート用の樹脂組成物である、上記態様１又は２に記載の樹脂組成物。
［４］ 前記式（１）中のＲ₁の少なくとも１つが、下記式（２）：

で表される基である、上記態様１〜３のいずれか１項に記載の樹脂組成物。
［５］ 前記ポリイミド前駆体が、下記式（３）：

｛式中、Ｒ₃及びＲ₄の各々は、複数ある場合それぞれ独立に、炭素数１〜５の１価の脂肪族炭化水素基、又は炭素数６〜１０の１価の芳香族基を示し、そしてｍは、１〜２００の整数である。｝で表される構造を有する、上記態様１〜４のいずれか１項に記載の樹脂組成物。
［６］ 前記ポリイミド前駆体が、ピロメリット酸二無水物を含むテトラカルボン酸二無水物とジアミンとの共重合体である、上記態様１〜５のいずれかに記載の樹脂組成物。
［７］ 前記ポリイミド前駆体が、３，３’，４，４’−ビフェニルテトラカルボン酸二無水物を含むテトラカルボン酸二無水物とジアミンとの共重合体である、上記態様１〜６のいずれかに記載の樹脂組成物。
［８］ 前記ポリイミド前駆体が、テトラカルボン酸二無水物とジアミンとの共重合体であり、 前記テトラカルボン酸二無水物が、ピロメリット酸二無水物及び３，３’，４，４’−ビフェニルテトラカルボン酸二無水物を、前記ピロメリット酸二無水物と前記３，３’，４，４’−ビフェニルテトラカルボン酸二無水物とのモル比２０：８０〜８０：２０で含む、上記態様１〜７のいずれかに記載の樹脂組成物。
［９］ 前記ポリイミド前駆体が、テトラカルボン酸二無水物と、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、２，２’−ビス（トリフルオロメチル）ベンジジン及び９，９−ビス（４−アミノフェニル）フルオレンからなる群から選択される１つ以上のジアミンとの共重合体である、上記態様１〜８のいずれかに記載の樹脂組成物。
［１０］ 前記ポリイミド前駆体の重量平均分子量が１６０，０００〜２２０，０００である、上記態様１〜９のいずれかに記載の樹脂組成物。
［１１］ 前記樹脂組成物は、フレキシブルデバイス用の樹脂組成物である、上記態様１〜１０のいずれかに記載の樹脂組成物。
［１２］ 前記樹脂組成物は、フレキシブルディスプレイ用の樹脂組成物である、上記態様１〜１１のいずれかに記載の樹脂組成物。
［１３］ 上記態様１〜１２のいずれかに記載の樹脂組成物の硬化物であるポリイミドフィルム。
［１４］ 膜厚１０μｍ換算での厚み方向レタデーション（Ｒｔｈ）が３００以下であり、及び／又は、膜厚１０μｍ換算での黄色度（ＹＩ）が２０以下である、上記態様１３に記載のポリイミドフィルム。
［１５］ 上記態様１３又は１４に記載のポリイミドフィルムを含むフレキシブルデバイス。
［１６］ 上記態様１３又は１４に記載のポリイミドフィルムを含むフレキシブルディスプレイ。
［１７］ 前記ポリイミドフィルムは、前記フレキシブルディスプレイを外部から観察した際に視認される箇所に配置されている、上記態様１６に記載のフレキシブルディスプレイ。
［１８］ 支持体の表面上に、上記態様１〜１２のいずれかに記載の樹脂組成物を塗布する塗布工程と、
前記樹脂組成物を加熱してポリイミドフィルムを形成する膜形成工程と、
前記ポリイミドフィルムを前記支持体から剥離する剥離工程と、を含む、ポリイミドフィルムの製造方法。
［１９］ 前記塗布工程は、前記樹脂組成物をスリットコートすることを含む、上記態様１８に記載のポリイミドフィルムの製造方法。
［２０］ 前記式（１）中のＲ₁の少なくとも１つが、下記式（２）：

で表される基である、上記態様１９に記載のポリイミドフィルムの製造方法。
［２１］ 前記ポリイミド前駆体が、下記式（３）：

｛式中、Ｒ₃及びＲ₄の各々は、複数ある場合それぞれ独立に、炭素数１〜５の１価の脂肪族炭化水素基、又は炭素数６〜１０の１価の芳香族基を示し、そしてｍは、１〜２００の整数である。｝で表される構造を有する、上記態様１９又は２０に記載のポリイミドフィルムの製造方法。
［２２］ 前記剥離工程に先立って、前記支持体側から前記ポリイミドフィルムにレ−ザ−を照射する照射工程を更に含む、上記態様１８〜２１のいずれかに記載のポリイミドフィルムの製造方法。
［２３］ 支持体の表面上に、上記態様１〜１２のいずれかに記載の樹脂組成物を塗布する塗布工程と、
前記樹脂組成物を加熱してポリイミドフィルムを形成する膜形成工程と、
前記ポリイミドフィルム上に素子を形成する素子形成工程と、
前記素子が形成された前記ポリイミドフィルムを前記支持体から剥離する剥離工程と、を含むディスプレイの製造方法。
［２４］ 前記塗布工程は、前記樹脂組成物をスリットコートすることを含む、上記態様２３に記載のディスプレイの製造方法。
［２５］ 前記ディスプレイを外部から観察した際に視認される箇所に前記ポリイミドフィルムを配置する、上記態様２３又は２４に記載のディスプレイの製造方法。As a result of diligent studies, the present inventors have found that the use of a polyimide precursor having a specific structure brings about good coating properties in a slit coat, as well as good mechanical and optical properties. ..
That is, the present invention includes the following aspects.
[1] The following equation (1):

{In the formula, R _1, each independently represent a divalent organic group and when a plurality of, R ₂ are each independently when a plurality of a tetravalent organic group, n is a positive integer. }, A resin composition containing a polyimide precursor having a structure represented by} and a solvent.
The polyimide precursor has a weight average molecular weight of 110,000 to 250,000.
A resin composition having a solid content of 10 to 25% by mass.
[2] When the viscosity of the resin composition is measured at 23 ° C. with a viscometer equipped with a temperature controller, the shear rate dependence (TI) represented by the following formula is 0.9 to 1.1. , The resin composition according to the above aspect 1.
TI = ηa / ηb
{In the formula, ηa (mPa · s) is the viscosity of the resin composition at the measured rotation speed a (rpm), and ηb (mPa · s) is the viscosity of the resin composition at the measured rotation speed b (rpm). However, a * 10 = b. }
[3] The resin composition according to the above aspect 1 or 2, wherein the resin composition is a resin composition for slit coating.
[4] At least one of R _{1 in} the above formula (1) is the following formula (2):

The resin composition according to any one of the above aspects 1 to 3, which is a group represented by.
[5] The polyimide precursor has the following formula (3):

{In the formula, each of R ₃ and R ₄ independently indicates a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms, respectively. , And m is an integer from 1 to 200. } The resin composition according to any one of the above aspects 1 to 4, which has a structure represented by.
[6] The resin composition according to any one of the above aspects 1 to 5, wherein the polyimide precursor is a copolymer of a tetracarboxylic dianhydride containing a pyromellitic dianhydride and a diamine.
[7] The above-mentioned aspects 1 to 6, wherein the polyimide precursor is a copolymer of a tetracarboxylic dianhydride containing 3,3', 4,4'-biphenyltetracarboxylic dianhydride and a diamine. The resin composition according to any one.
[8] The polyimide precursor is a copolymer of tetracarboxylic dianhydride and diamine, and the tetracarboxylic dianhydride is pyromellitic dianhydride and 3,3', 4,4'. -The biphenyltetracarboxylic dianhydride is contained in a molar ratio of the pyromellitic dianhydride to the 3,3', 4,4'-biphenyltetracarboxylic dianhydride at a molar ratio of 20:80 to 80:20. The resin composition according to any one of the above aspects 1 to 7.
[9] The polyimide precursors are tetracarboxylic acid dianhydride, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,2'-bis (trifluoromethyl) benzidine and 9, The resin composition according to any one of aspects 1 to 8 above, which is a copolymer with one or more diamines selected from the group consisting of 9-bis (4-aminophenyl) fluorene.
[10] The resin composition according to any one of the above aspects 1 to 9, wherein the polyimide precursor has a weight average molecular weight of 160,000 to 220,000.
[11] The resin composition according to any one of the above aspects 1 to 10, wherein the resin composition is a resin composition for a flexible device.
[12] The resin composition according to any one of the above aspects 1 to 11, wherein the resin composition is a resin composition for a flexible display.
[13] A polyimide film which is a cured product of the resin composition according to any one of the above aspects 1 to 12.
[14] The polyimide film according to the above aspect 13, wherein the thickness direction retardation (Rth) in terms of film thickness of 10 μm is 300 or less, and / or the yellowness (YI) in terms of film thickness of 10 μm is 20 or less. ..
[15] A flexible device comprising the polyimide film according to the above aspect 13 or 14.
[16] A flexible display comprising the polyimide film according to the above aspect 13 or 14.
[17] The flexible display according to the above aspect 16, wherein the polyimide film is arranged at a position that can be visually recognized when the flexible display is observed from the outside.
[18] A coating step of applying the resin composition according to any one of the above aspects 1 to 12 on the surface of the support.
A film forming step of heating the resin composition to form a polyimide film, and
A method for producing a polyimide film, which comprises a peeling step of peeling the polyimide film from the support.
[19] The method for producing a polyimide film according to the above aspect 18, wherein the coating step includes slit-coating the resin composition.
[20] At least one of R _{1 in} the above formula (1) is the following formula (2):

The method for producing a polyimide film according to the above aspect 19, which is a group represented by.
[21] The polyimide precursor has the following formula (3):

{In the formula, each of R ₃ and R ₄ independently indicates a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms, respectively. , And m is an integer from 1 to 200. } The method for producing a polyimide film according to the above aspect 19 or 20, which has a structure represented by.
[22] The method for producing a polyimide film according to any one of the above aspects 18 to 21, further comprising an irradiation step of irradiating the polyimide film with a laser from the support side prior to the peeling step.
[23] A coating step of applying the resin composition according to any one of the above aspects 1 to 12 on the surface of the support.
A film forming step of heating the resin composition to form a polyimide film, and
The element forming step of forming an element on the polyimide film and
A method for manufacturing a display, comprising a peeling step of peeling the polyimide film on which the element is formed from the support.
[24] The method for manufacturing a display according to the above aspect 23, wherein the coating step includes slit-coating the resin composition.
[25] The method for manufacturing a display according to the above aspect 23 or 24, wherein the polyimide film is arranged at a position that is visible when the display is observed from the outside.

According to one aspect of the present invention, it is possible to provide a polyimide precursor-containing resin composition which is excellent in coating properties in slit coating and also excellent in mechanical properties and optical properties required for applications such as flexible substrates.

It is a figure which shows the structure above the polyimide substrate of the top emission type flexible organic EL display as an example of the display provided by one aspect of this invention.

Hereinafter, an exemplary embodiment of the present invention (hereinafter, abbreviated as “embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof. In addition, unless otherwise specified, the characteristic values described in the present disclosure are values measured by the method described in the section of [Example] or a method understood by those skilled in the art to be equivalent thereto. Intended.

｛式中、Ｒ₁は、複数ある場合それぞれ独立に２価の有機基を示し、Ｒ₂は、複数ある場合それぞれ独立に４価の有機基を示し、ｎは正の整数である。｝
で表される構造を有するポリイミド前駆体を含む樹脂組成物を提供する。一態様において、当該樹脂組成物は、当該ポリイミド前駆体と溶媒とを含む。This embodiment is
The following formula (1):

{In the formula, R _1, each independently represent a divalent organic group and when a plurality of, R ₂ are each independently when a plurality of a tetravalent organic group, n is a positive integer. }
Provided is a resin composition containing a polyimide precursor having a structure represented by. In one aspect, the resin composition comprises the polyimide precursor and a solvent.

で表される基である。In a preferred embodiment, at least one of R ₁ in the formula (1) is the following formula (2):

It is a group represented by.

The fact that at least one of R ₁ in the formula (1) has a structure represented by the formula (2) contributes to good optical properties (particularly Rth) and heat resistance of polyimide, which is a cured product of the polyimide precursor. .. In one embodiment, it has a structure in which all of n R ₁ in the formula (1) is represented by the formula (2). Also, in one embodiment, the ratio of the structure represented by formula (1) n-number of out formula of R ₁ in (2) is 0% or more, or 10% or more, or may be 20% or more, It may be 100% or less, or 90% or less.

The present embodiment is also a resin composition containing a polyimide precursor having a structure represented by the above formula (1), and the polyimide which is a cured product of the resin composition is a thickness direction retardation (Rth) 300. Also provided are resin compositions having the following and / or yellowness (YI) of 20 or less. The low thickness direction retardation (Rth) indicates that the polyimide has low birefringence, and the low yellowness (YI) described above indicates that the polyimide has a good color tone (that is, is almost colorless). It represents that.

Since the resin composition of the present embodiment provides a polyimide film having excellent slit coating performance and excellent mechanical and optical properties, it is preferably for a flexible device (for example, for a flexible substrate), and particularly preferably. It is useful for flexible displays.

(Weight average molecular weight of polyimide precursor)
In one aspect, the weight average molecular weight of the polyimide precursor is 110,000 or more and 250,000 or less. The present inventor has found that when the resin composition of the present embodiment is used for slit coating, the weight average molecular weight of the polyimide precursor has a great influence on the coating performance, and repeated diligent studies. As a result, when the weight average molecular weight of the polyimide precursor is 110,000 or more, the solid content of the resin composition can be adjusted to realize a good slit coat, while the weight average molecular weight is 250,000 or less. We have found that the polyimide precursor is easy to produce. That is, in the present embodiment, the weight average molecular weight of the polyimide precursor is 110,000 or more from the viewpoint of coating performance and 250,000 or less from the viewpoint of ease of manufacture.

The desired weight average molecular weight of the polyimide precursor may vary depending on the desired application, the type of the polyimide precursor, the solid content of the resin composition, the type of solvent that the resin composition can contain, and the like.

For example, preferred examples of the lower limit of the weight average molecular weight are 111,000, 112,000, 113,000, 114,000, 115,000, 116,000, 117,000, 118,000, 119,000, 120, 000, 121,000, 122,000, 123,000, 124,000, 125,000, 126,000, 127,000, 128,000, 129000, 130,000, 131,000, 132,000, 133,000, 134,000, 135,000, 136,000, 137,000, 138,000, 139,000, 140,000, 141,000, 142,000, 143,000, 144,000, 145, 000, 146,000, 147,000, 148,000, 149,000, 150,000, 151,000, 152,000, 153,000, 154,000, 155,000, 156,000, 157,000, 158,000, 159,000, 160,000, 161,000, 162,000, 163,000, 164,000, 165,000, 166,000, 167,000, 168,000, 169,000, 170, 000, 171,000, 172,000, 173,000, 174,000, 175,000, 176,000, 177,000, 178,000, 179,000, 180,000, 181,000, 182,000, 183,000, 184,000, 185,000, 186,000, 187,000, 188,000, 189,000, 190,000, 191,000, 192,000, 193,000, 194,000, 195, 000, 196,000, 197,000, 198,000, 199,000, 200,000, 201,000, 202,000, 203,000, 204,000, 205,000, 206,000, 207,000, 208,000, 209,000, 210,000, 211,000, 212,000, 213,000, 214,000, 215,000, 216,000, 217,000, 218,000, 219,000, 220, 000, 221,000, 222,000, 223,000, 224,000, 225,000, 226,000, 227,000, 228,000, 229000, 230,000, 231,000, 232,000, 23 3,000, 234,000, 235,000, 236,000, 237,000, 238,000, 239,000, 240,000, 241,000, 242,000, 243,000, 244,000, 245, 000, 246,000, 247,000, 248,000, or 249,000.

Further, preferred examples of the upper limit of the weight average molecular weight are 249,000, 248,000, 247,000, 246,000, 245,000, 244,000, 243,000, 242,000, 241,000, 240, 000, 239,000, 238,000, 237,000, 236,000, 235,000, 234,000, 233,000, 232,000, 231,000, 230,000, 229,000, 228,000, 227,000, 226,000, 225,000, 224,000, 223,000, 222,000, 221,000, 220,000, 219,000, 218,000, 217,000, 216,000, 215, 000, 214,000, 213,000, 212,000, 211,000, 210,000, 209,000, 208,000, 207,000, 206,000, 205,000, 204,000, 203,000, 202,000, 201,000, 200,000, 199,000, 198,000, 197,000, 196,000, 195,000, 194,000, 193,000, 192,000, 191,000, 190, 000, 189,000, 188,000, 187,000, 186,000, 185,000, 184,000, 183,000, 182,000, 181,000, 180,000, 179,000, 178,000, 177,000, 176,000, 175,000, 174,000, 173,000, 172,000, 171,000, 170,000, 169,000, 168,000, 167,000, 166,000, 165, 000, 164,000, 163,000, 162,000, 161,000, 160,000, 159,000, 158,000, 157,000, 156,000, 155,000, 154,000, 153,000, 152,000, 151,000, 150,000, 149,000, 148,000, 147,000, 146,000, 145,000, 144,000, 143,000, 142,000, 141,000, 140, 000, 139,000, 138,000, 137,000, 136,000, 135,000, 134,000, 133,000, 132,000, 131,000, 130,000, 129,000, 128,000, 127 000, 126,000, 125,000, 124,000, 123,000, 122,000, 121,000, 120,000, 119,000, 118,000, 117,000, 116,000, 115,000 , 114,000, 113,000, 112,000, or 111,000.

For example, from the viewpoint of elongation and yellowness (YI) of a cured product of a resin composition containing a polyimide precursor (for example, a polyimide film (also referred to as a cure film in the present disclosure)), a weight average molecular weight of 120,000 or more is preferable. , 130,000 or more is more preferable, and 160,000 or more is particularly preferable. Further, from the viewpoint of haze of the cured product (for example, a polyimide film), 220,000 or less is preferable, and 200,000 or less is more preferable. In a preferred embodiment, the polyimide precursor has a weight average molecular weight of 160,000 or more and 220,000 or less.

(Polyimide film thickness direction retardation (Rth))
When a polyimide film is prepared as a cured product (that is, an imidized product) of a polyimide precursor, the thickness direction retardation (Rth) of the polyimide film at a thickness of 10 μm differs depending on the monomer skeleton of the polyimide precursor, but is the same monomer skeleton. If so, the larger the weight average molecular weight of the polyimide precursor, the smaller the Rth tends to be. When DAS is used as the polymer skeleton, Rth tends to decrease. The mechanism of the above relationship between the weight average molecular weight of the polyimide precursor and the Rth of the polyimide film is unknown, but it is considered that the molecular orientation and crystallinity of the polyimide film are related.

In a particular embodiment, Rth is 300 nm or less from the viewpoint of obtaining a polyimide film having low birefringence. In particular, when a polyimide film is used as a display material, the Rth is preferably 200 nm or less, more preferably 100 nm or less, more preferably 80 nm or less, more preferably 50 nm or less, and particularly preferably 30 nm. When Rth is 300 nm or less, it is easy to capture an image image correctly, and particularly when Rth is 200 nm or less, the color reproducibility of the image is good.

In one aspect, the polyimide film has a thickness direction retardation (Rth) of 300 nm or less in terms of a film thickness of 10 μm and / or a yellowness (YI) of 20 or less in terms of a film thickness of 10 μm. In one aspect, the polyimide film has a thickness direction retardation (Rth) of 300 nm or less in terms of a film thickness of 10 μm and a yellowness (YI) of 20 or less in terms of a film thickness of 10 μm.

(Yellowness of polyimide film (YI))
In a specific embodiment, when a polyimide film is produced as a cured product (that is, an imidized product) of a polyimide precursor, the yellowness (YI) of the polyimide film at a film thickness of 10 μm is 20 or less from the viewpoint of obtaining good optical characteristics. It is preferably 18 or less, more preferably 16 or less, still more preferably 14 or less, still more preferably 13 or less, still more preferably 10 or less, and particularly preferably 7 or less. The YI of the polyimide film at a thickness of 10 μm differs depending on the monomer skeleton of the polyimide precursor, but if the monomer skeleton is the same, the larger the weight average molecular weight of the polyimide precursor, the smaller the YI tends to be.

(Other preferred properties of polyimide film)
When a polyimide film is formed on an inorganic supporting substrate such as a glass substrate as a cured product (that is, an imidized product) of the polyimide precursor, the residual stress generated between the polyimide film and the glass substrate at a thickness of 10 μm is, for example, From the viewpoint of reducing the amount of warpage of the glass substrate with polyimide in manufacturing for display applications, it is preferably 25 MPa or less, more preferably 23 MPa or less, still more preferably 20 MPa or less, still more preferably 18 MPa or less, and particularly preferably 16 MPa or less.

Further, it is preferable that the tensile elongation of the polyimide film at a film thickness of 10 μm is 15% or more. The tensile elongation is more preferably 20% or more, further preferably 25% or more, further preferably 30% or more, still more preferably 35% or more, and particularly preferably 35% or more, from the viewpoint of the mechanical strength of the flexible display. It is preferably 40% or more. The tensile elongation of the polyimide film differs depending on the monomer skeleton of the polyimide precursor, but if the monomer skeleton is the same, the larger the weight average molecular weight of the polyimide precursor, the larger the tensile elongation tends to be.

The glass transition temperature Tg of the polyimide film is preferably 360 ° C. or higher, more preferably 400 ° C. or higher, from the viewpoint of further raising the process temperature when forming an inorganic film such as silicon nitride on the polyimide in the CVD step. It is preferable, and 470 ° C. or higher is more preferable.

The polyimide film preferably has a uniform film thickness. In particular, when a polyimide film is used as a screen material for a flexible display or the like, the wavelength of visible light is about 380 nm to about 700 nm, so that a particularly high film thickness is obtained from the viewpoint of obtaining good display performance and from the viewpoint of the display manufacturing process. Uniformity is required. The film thickness uniformity (standard deviation of a plurality of film thickness points) of the polyimide film is preferably 10 μm or less, preferably 8 μm or less, preferably 5 μm or less, preferably 3 μm or less, preferably 2 μm or less, particularly preferably 1 μm or less, and 500 nm. The following is particularly preferable, and 300 nm or less is particularly preferable. The smaller the film thickness uniformity is, the more preferable it is, but from the viewpoint of improving the yield of display production, it may be, for example, 50 nm or more, or 100 nm or more. The film thickness uniformity means a value of 3σ calculated from the film thickness of a plurality of points as measured by the method described in the [Example] section of the present disclosure, for example.

(Dependency on shear rate of resin composition)
The shear rate dependence (TI) (hereinafter, also simply referred to as TI) of the resin composition of the present embodiment is preferably 0.9 or more and 1.1 or less. In the present disclosure, TI measures the viscosity of a resin composition at 23 ° C. with a viscometer equipped with a temperature controller (TVE-35H manufactured by Toki Sangyo Kikai Co., Ltd.), and the viscosity ηa at the measurement rotation speed a (rpm). From (mPa · s) and the viscosity ηb (mPa · s) at the measured rotation speed b (rpm) (where a * 10 = b), the following formula:
TI = ηa / ηb
It is a value obtained according to. Details of the measurement conditions will be described in the description in the examples.

The shear rate dependence (TI) is preferably 0.9 or more, 0.95 or more, or 1.0 or more, and preferably 1.1 or less, 1.05 or less, or 1.0 or less. Is. When the TI is in this range, the resin composition is called a Newtonian fluid, and it is preferable because the film thickness uniformity when the resin composition is slit-coated is good. A polyimide film obtained by curing a resin composition having good film thickness uniformity has good film thickness uniformity, and therefore can be suitably used as a screen material for a flexible display or the like.

The detailed reason why the film thickness uniformity becomes good when the shear rate dependence of the resin composition is 0.9 or more and 1.1 or less is unclear, but it is considered as follows.
In the slit coat, the shear rate given to the resin composition immediately after the start of coating is low, and the shear rate given to the resin composition when the coating is continued is high. When the shear rate dependence is small (specifically, TI is 0.9 or more and 1.1 or less), the difference in viscosity of the resin composition immediately after the start of coating and when the coating is continued is small, so that the coating direction (MD) (Machine shear)) The film thickness variation is small (that is, the film thickness uniformity in the coating direction is good). Further, in the case where the slit coat nozzle injects the resin composition from only one end in the width direction (TD (Transverse direction)), the shear rate of the resin composition is large in the vicinity of the injection port at the time of slit coating. On the side opposite to the injection port (that is, the deadlock side of the nozzle), the shear rate of the resin composition becomes small. Even in such a case, the variation in film thickness in the width direction can be reduced by reducing the shear rate dependence (specifically, TI is 0.9 or more and 1.1 or less). As described above, the small shear rate dependence (specifically, TI of 0.9 or more and 1.1 or less) reduces the influence of shear on the viscosity, and the film thickness variation is small in both MD and TD. It gives the advantage (that is, the film thickness uniformity is good).

The shear rate dependence of the resin composition is considered to correlate with the method of synthesizing the resin composition.
For example, when all of acid dianhydride, diamine, and silicone oil which can be acid dianhydride or diamine depending on the structure are added to the reaction vessel and heated for reaction, and when the diamine is dissolved in a solvent. Comparing the case where the acid diamine and the silicone oil dissolved in a solvent are added dropwise at room temperature over time and reacted little by little, in the former case, the monomer (that is, the acid diamine) , Diamine and silicone oil), which are more reactive (higher acidity or basicity, less steric hindrance, etc.), and the polyimide precursor tends to become a block polymer. On the other hand, in the latter case, since the acid dianhydride and the silicone oil are dissolved in a solvent and added dropwise little by little, each monomer can react regardless of reactivity and the polyimide precursor tends to be a random polymer. is there. As described above, it is considered that the polymer composition of the product is different between the former and the latter. In the case of a block polymer (the former), since specific monomers are gathered in the polymer, intermolecular interactions are likely to occur between the polymer chains, and the flexibility of the polymer is impaired, so that the polymer chains are stacked. It will be easier. As a result, it is considered that the shear rate dependence of the resin composition increases. On the other hand, in the latter case, since each monomer is bonded in order and intermolecular interaction and the like are unlikely to occur, it is considered that the shear rate dependence is small.

Further, in the former case, since all the monomers are added and heated, it is considered that the acid dianhydride group is opened by heat, especially in some acid dianhydrides, before reacting with the polymer chain. When the acid dianhydride group is ring-opened to become a dicarboxyl group, the reactivity is lower than that of the acid dianhydride group, and it is considered that the molecular weight of the polyimide precursor is reduced. On the other hand, in the latter case, since the acid dianhydride is dissolved in a solvent and added dropwise at room temperature, the acid dianhydride group can react with the polymer chain without opening the ring. It is thought that the molecular weight will increase.

(Slit coat characteristics of resin composition)
The coating property (slit coating property) of the resin composition containing the polyimide precursor by the slit nozzle has a correlation with the weight average molecular weight of the polyimide precursor and the solid content of the resin composition. When the polyimide precursor has a low molecular weight and / or when the resin composition has a low solid content content, liquid leakage from the nozzle is likely to occur, while when the polyimide precursor has a high molecular weight, And / or when the resin composition has a high solid content, clogging of the varnish is likely to occur at the tip of the nozzle. Therefore, it is preferable to control the weight average molecular weight of the polyimide precursor within a range in which the desired slit coat characteristics can be obtained by controlling the solid content.

(Edge characteristics of coating film)
When the resin composition containing the polyimide precursor is slit-coated to form a dry coating film, if the polyimide precursor has a low molecular weight and / or if the resin composition has a low solid content, the edge On the other hand, when the polyimide precursor has a high molecular weight and / or the resin composition has a high solid content content, an edge bead (that is, edge swelling) is likely to occur. .. Therefore, it is preferable to control the weight average molecular weight of the polyimide precursor within a range in which the desired edge characteristics can be obtained by controlling the solid content.

In one embodiment, the solid content of the resin composition is 10% by mass to 25% by mass. The configurable coat gap (that is, the gap between the tip of the slit coat nozzle and the substrate) when slit-coating the resin composition correlates with the solid content of the resin composition, and the solid content contained in the resin composition. If the types are the same, the smaller the solid content of the resin composition, the larger the coat gap tends to be. From the viewpoint of good coating, it is preferable that the coat gap is large. For example, when the coat gap is 50 μm or more, collision between the slit nozzle and the substrate can be avoided even when the substrate size is relatively large. When the solid content of the resin composition is 10% by mass to 25% by mass, the desired coat gap can be realized by selecting the type and molecular weight of the polyimide precursor. The preferred solid content of the resin composition may vary depending on the desired application, the type and molecular weight of the polyimide precursor, the type of solvent that the resin composition can contain, and the like.

Preferred examples of the lower limit of the solid content content are 11% by mass, 12% by mass, 13% by mass, 14% by mass, 15% by mass, 16% by mass, 17% by mass, 18% by mass, 19% by mass, and 20% by mass. , 21% by mass, 22% by mass, 23% by mass, or 24% by mass.

Preferred examples of the upper limit of the solid content content are 24% by mass, 23% by mass, 22% by mass, 21% by mass, 20% by mass, 19% by mass, 18% by mass, 17% by mass, 16% by mass, and 15% by mass. , 14% by mass, 13% by mass, 12% by mass, or 11% by mass.

In a preferred embodiment, the solid content concentration is 10 to 20% by mass, more preferably 10 to 15% by mass.

｛式中、Ｒ₃及びＲ₄の各々は、複数ある場合それぞれ独立に、炭素数１〜５の１価の脂肪族炭化水素基、又は炭素数６〜１０の１価の芳香族基を示し、そしてｍは、１〜２００の整数である。｝で表される構造を有する。
Ｒ₃及びＲ₄が炭素数１〜５の１価の脂肪族炭化水素基又は炭素数６〜１０の１価の芳香族基であることは、支持体との間に発生する残留応力及びＲｔｈを低減できるポリイミドを得る観点から有利である。Ｒ₃及びＲ₄の好ましい構造としては、メチル基、エチル基、プロピル基、ブチル基、フェニル基等が挙げられる。
ｍは、支持体との間に発生する残留応力及びＲｔｈを低減できるポリイミドを得る観点から、１〜２００であり、好ましくは、１以上、又は３以上、又は５以上、好ましくは、２００以下、又は１８０以下、又は１６０以下である。In a preferred embodiment, the polyimide precursor is of formula (3):

{In the formula, each of R ₃ and R ₄ independently indicates a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms, respectively. , And m is an integer from 1 to 200. } Has a structure represented by.
The fact that R ₃ and R ₄ are monovalent aliphatic hydrocarbon groups having 1 to 5 carbon atoms or monovalent aromatic groups having 6 to 10 carbon atoms means that the residual stress generated between them and the support and Rth It is advantageous from the viewpoint of obtaining a polyimide capable of reducing the amount of Preferred structures of R ₃ and R ₄ include a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group and the like.
m is 1 to 200, preferably 1 or more, 3 or more, or 5 or more, preferably 200 or less, from the viewpoint of obtaining a polyimide capable of reducing residual stress and Rth generated between the support and the support. Or 180 or less, or 160 or less.

The polyimide precursor may have the structure of the formula (3) at any site in the molecule, but the structure of the formula (3) is preferably derived from the diamine component from the viewpoint of the type and cost of the siloxane monomer. .. The ratio of the structural portion represented by the formula (3) to the total mass of the polyimide precursor is preferably 5% by mass or more, more preferably 5% by mass or more, from the viewpoint of reducing the residual stress and Rth generated between the polyimide precursor and the support. 6% by mass or more, more preferably 7% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, from the viewpoint of transparency and heat resistance of the obtained cured product (for example, polyimide film). More preferably, it is 25% by mass or less.

In a typical embodiment, the polyimide precursor having the structure represented by the above formula (1) is a polymer of a diamine component containing an R ₁ group and an acid dianhydride component containing an R ₂ group.

Examples of acid dianhydrides containing R ₂ groups include pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride. Acid dianhydride, 4,4'-(hexafluoroisopropyridene) diphthalic dianhydride, 5- (2,5-dioxotetrahydro-3-franyl) -3-methyl-cyclohexene-1,2dicarboxylic dianhydride , 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-benzophenonetetracarboxylic dianhydride Anhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, methylene-4,4'-diphthalic acid dianhydride, 1,1-ethylidene-4,4'-diphthalic acid dianhydride , 2,2-Propyridene-4,4′-diphthalic dianhydride, 1,2-ethylene-4,4′-diphthalic acid dianhydride, 1,3-trimethylened-4,4′-diphthalic acid dianhydride Anhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, p-phenylenebis (trimelitate acid anhydride), thio-4,4'-diphthalic acid dianhydride, sulfonyl-4,4'-diphthalic acid dianhydride, 1,3-bis (3,4-dicarboxyphenyl) ) Benzene dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,3-bis [ 2- (3,4-dicarboxyphenyl) -2-propyl] benzene dianhydride, 1,4-bis [2- (3,4-dicarboxyphenyl) -2-propyl] benzene dianhydride, bis [ 3- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, bis [4- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, 2,2-bis [3- (3,4) -Dicarboxyphenoxy) phenyl] propane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, bis (3,4-dicarboxyphenoxy) dimethylsilane dianhydride , 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1 , 4,5,8-naphthalenetetracarboxylic dianhydride , 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1 , 2,7,8-Phenantrene tetracarboxylic dianhydride and the like can be exemplified.

Among them, pyromellitic dianhydride (PMDA) and biphenyltetracarboxylic dianhydride (BPDA) are used when the solid content of the resin composition is controlled within a predetermined weight average molecular weight of the polyimide precursor. It is preferable from the viewpoint of good slit coating performance, good mechanical properties and optical properties of a cured product (for example, a polyimide film), and high glass transition temperature. In one aspect, the polyimide precursor having the structure represented by the formula (1) is a copolymer of tetracarboxylic dianhydride and diamine. In one embodiment, the polyimide precursor is a copolymer of a tetracarboxylic dianhydride containing pyromellitic dianhydride (PMDA) and a diamine. In one embodiment, the polyimide precursor is a copolymer of a tetracarboxylic dianhydride containing 3,3', 4,4'-biphenyltetracarboxylic dianhydride and a diamine.

In certain embodiments, the total content of pyromellitic dianhydride (PMDA) and biphenyltetracarboxylic dianhydride (BPDA) in the total acid dianhydride provides good slit coating performance as well as a cured product (BPDA). From the viewpoint of obtaining good thickness direction retardation (Rth), yellowness (YI), glass transition temperature Tg, and elongation of (for example, a polyimide film), it is preferably 60 mol% or more, more preferably 80 mol% or more, particularly preferably. Is 100 mol%.

In certain embodiments, the content of pyromellitic dianhydride (PMDA) in the total acid dianhydride provides good slit coating performance as well as good glass transition temperature Tg of the cured product (eg, polyimide film). From the viewpoint of obtaining, 0 mol% or more is preferable, 10 mol% or more is preferable, 20 mol% or more is preferable, 100 mol% or less is preferable, and 90 mol% or less is preferable.

In certain embodiments, the content of biphenyltetracarboxylic dianhydride (BPDA) in total acid dianhydride provides good slit coating performance as well as good, thickness direction retardation of the cured product (eg, polyimide film). From the viewpoint of obtaining (Rth), yellowness (YI), and elongation, 0 mol% or more is preferable, 10 mol% or more is preferable, 20 mol% or more is preferable, 100 mol% or less is preferable, and 90 mol% or less is preferable. Is preferable.

In a particular embodiment, the content ratio of pyromellitic dianhydride (PMDA): biphenyltetracarboxylic dianhydride (BPDA) in the acid dianhydride is a good thickness direction retardation of the cured product (eg, polyimide film). From the viewpoint of achieving both (Rth), yellowness (YI) and heat resistance typified by the glass transition temperature, 20:80 to 80:20 is preferable, and 30:70 to 70:30 is more preferable. In certain embodiments, the polyimide precursor is a copolymer of a tetracarboxylic dianhydride and a diamine, wherein the tetracarboxylic dianhydride is a pyromellitic dianhydride and 3,3', 4,4. '-Biphenyltetracarboxylic dianhydride, pyromellitic dianhydride: 3,3', 4,4'-biphenyltetracarboxylic dianhydride having a molar ratio of 20:80 to 80:20, more preferably 30 : Included at 70 to 70:30.

Examples of the diamine containing the R ₁ group in the formula (1) include diaminodiphenylsulfone (for example, 4,4'-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone), 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- (4- (4-)4-) Aminophenoxy) phenyl) hexafluoropropane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, and the like can be mentioned.

The diamine used to form the polyimide precursor having the structure represented by the formula (1) is diaminodiphenylsulfone (for example, 4,4'-diaminodiphenylsulfone and / or 3,3′-diaminodiphenylsulfone). It is preferable to include it.

The content of diaminodiphenyl sulfone in the total diamine is preferably 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and may be 95 mol% or more. The larger the amount of diaminodiphenyl sulfone, the more preferable it is from the viewpoint of yellowness (YI) of the cured product (for example, polyimide film), glass transition temperature Tg, and retardation Rth in the thickness direction. As the diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone is particularly preferable from the viewpoint of low yellowness (YI).

In a preferred embodiment, the diamine to be copolymerized with diaminodiphenylsulfone is preferably diamidebiphenyls, more preferably diaminobis (tri) from the viewpoint of heat resistance of a cured product (for example, a polyimide film) and yellowness (YI). Includes fluoromethyl) biphenyl (TFMB). The content of diaminobis (trifluoromethyl) biphenyl (TFMB) in the total diamine is preferably 20 mol% or more, more preferably 30 mol% or more, from the viewpoint of the yellowness (YI) of the cured product (for example, polyimide film). From the viewpoint of allowing the diamine to contain other advantageous components such as diaminodiphenylsulfone, it is preferably 80 mol% or less, more preferably 70 mol% or less.

｛式中、Ｒ₅は二価の炭化水素基を示し、それぞれ同一でも異なっていてもよく、複数のＲ₃及びＲ₄の各々は、式（３）で定義したのと同様であり、そしてｌは１〜２００の整数を表す。｝で表されるジアミノ（ポリ）シロキサンを好適に用いることができる。In a preferred embodiment, the diamine comprises a silicon-containing diamine. In a more preferred embodiment, the diamine comprises a silicon-containing diamine containing the structure represented by the above formula (3). Examples of the silicon-containing diamine include the following formula (3a):

{In the formula, R ₅ represents a divalent hydrocarbon group, which may be the same or different, and each of the plurality of R ₃ and R ₄ is the same as defined in formula (3), and l represents an integer of 1 to 200. } A diamino (poly) siloxane represented by} can be preferably used.

Preferred structures of R _{5 in} the general formula (3a) include a methylene group, an ethylene group, a propylene group, a butylene group, a phenylene group and the like. In addition, preferred structures of R ₃ and R _{4 in} the formula (3a) include a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group and the like.

The number average molecular weight of the compound represented by the above formula (3a) is preferably 500 or more, more preferably 500 or more, from the viewpoint of reducing the residual stress generated between the obtained cured product (for example, polyimide film) and the support. Is 1,000 or more, more preferably 2,000 or more, and from the viewpoint of transparency (particularly low HAZE) of the obtained cured product (for example, polyimide film), it is preferably 12,000 or less, more preferably 10,000 or more. Below, it is more preferably 8,000 or less.

Specific examples of the compound represented by the above formula (3a) include both-terminal amine-modified methylphenyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: X22-1660B-3 (number average molecular weight 4400), X22-9409 (number average). Molecular weight 1300)), both-terminal amino-modified dimethyl silicone (manufactured by Shin-Etsu Chemical Co., Ltd .: X22-161A (number average molecular weight 1600), X22-161B (number average molecular weight 3000), KF8012 (number average molecular weight 4400), manufactured by Toray Dow Corning: BY16-835U (number average molecular weight 900) manufactured by Chisso: Silaplane FM3311 (number average molecular weight 1000)) and the like can be mentioned. Among these, both-terminal amine-modified methylphenyl silicone oil is preferable from the viewpoint of improving chemical resistance and Tg.

The copolymerization ratio of the silicon-containing diamine is preferably in the range of 0.5 to 30% by mass, more preferably 1.0% by mass to 25% by mass, and further preferably 1.5 to the mass of the total polyimide precursor. It is from mass% to 20% by mass. When it is 0.5% by mass or more, the effect of reducing the stress generated between the support and the support is good. Further, when it is 30% by mass or less, the transparency (particularly low HAZE) of the obtained cured product (for example, polyimide film) is good, which is preferable in terms of realizing high total light transmittance and preventing reduction of Tg.

As the acid component for forming the polyimide precursor in the present embodiment, a dicarboxylic acid is used in addition to the acid dianhydride (for example, the tetracarboxylic dianhydride exemplified above) as long as its performance is not impaired. You may use it. That is, the polyimide precursor of the present disclosure may be a polyamide-imide precursor. A film obtained from such a polyimide precursor can have good performances such as mechanical elongation, glass transition temperature Tg, and yellowness (YI). Examples of the dicarboxylic acid used include a dicarboxylic acid having an aromatic ring and an alicyclic dicarboxylic acid. In particular, it is preferably at least one compound selected from the group consisting of aromatic dicarboxylic acids having 8 to 36 carbon atoms and alicyclic dicarboxylic acids having 6 to 34 carbon atoms. The number of carbons referred to here also includes the number of carbons contained in the carboxyl group. Of these, a dicarboxylic acid having an aromatic ring is preferable.

Specifically, for example, isophthalic acid, terephthalic acid, 4,4'-biphenyldicarboxylic acid, 3,4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3. -Naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-sulfonylbis benzoic acid, 3,4'-sulfonylbis benzoic acid, 3,3'-sulfonylbis benzoic acid , 4,4'-oxybis benzoic acid, 3,4'-oxybis benzoic acid, 3,3'-oxybis benzoic acid, 2,2-bis (4-carboxyphenyl) propane, 2,2-bis (3-carboxy) Phenyl) propane, 2,2'-dimethyl-4,4'-biphenyldicarboxylic acid, 3,3'-dimethyl-4,4'-biphenyldicarboxylic acid, 2,2'-dimethyl-3,3'-biphenyldicarboxylic acid Acid, 9,9-bis (4- (4-carboxyphenoxy) phenyl) fluorene, 9,9-bis (4- (3-carboxyphenoxy) phenyl) fluorene, 4,4'-bis (4-carboxyphenoxy) Biphenyl, 4,4'-bis (3-carboxyphenoxy) biphenyl, 3,4'-bis (4-carboxyphenoxy) biphenyl, 3,4'-bis (3-carboxyphenoxy) biphenyl, 3,3'-bis (4-carboxyphenoxy) biphenyl, 3,3'-bis (3-carboxyphenoxy) biphenyl, 4,4'-bis (4-carboxyphenoxy) -p-terphenyl, 4,4'-bis (4-carboxy) Phenoxy) -m-terphenyl, 3,4'-bis (4-carboxyphenoxy) -p-terphenyl, 3,3'-bis (4-carboxyphenoxy) -p-terphenyl, 3,4'-bis (4-Carboxyphenoxy) -m-terphenyl, 3,3'-bis (4-carboxyphenoxy) -m-terphenyl, 4,4'-bis (3-carboxyphenoxy) -p-terphenyl, 4, 4'-bis (3-carboxyphenoxy) -m-terphenyl, 3,4'-bis (3-carboxyphenoxy) -p-terphenyl, 3,3'-bis (3-carboxyphenoxy) -p-ter Phenyl, 3,4'-bis (3-carboxyphenoxy) -m-terphenyl, 3,3'-bis (3-carboxyphenoxy) -m-terphenyl, 1,1-cyclobutanedicarboxylic acid, 1,4- Cyclohexanedicarboxylic acid, 1,2-Cyclohexanedicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 1,3-phenylene diacetic acid, 1,4-phenylene diacetic acid, etc .; and 5-aminoisophthal as described in WO 2005/068535. Examples include acid derivatives. When these dicarboxylic acids are actually copolymerized with a polymer, they may be used in the form of an acid chloride form derived from thionyl chloride or the like, an active ester form or the like.

In a preferred embodiment, the polyimide precursors are tetracarboxylic acid dianhydride and 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,2'-bis (trifluoromethyl) benzidine and 9 , 9-Bis (4-aminophenyl) fluorene, is a copolymer with one or more diamines selected from the group.

Particularly preferable polyimide precursors include the following.
(1) A polycondensate of a material component in which the acid dianhydride component is pyromellitic dianhydride (PMDA) and biphenyltetracarboxylic dianhydride (BPDA) and the diamine component is diaminodiphenylsulfone (DAS) (more preferable). Weight average molecular weight 110,000 to 130,000, solid content 12 to 25% by mass)
(2) Polycondensation of a material component in which the acid dianhydride component is pyromellitic dianhydride (PMDA) and biphenyltetracarboxylic dianhydride (BPDA), and the diamine component is diaminodiphenylsulfone (DAS) and a silicon-containing diamine. (Preferably, weight average molecular weight 110,000 to 210,000, solid content content 10 to 25% by mass)
(3) The acid dianhydride component is pyromellitic dianhydride (PMDA) and biphenyltetracarboxylic dianhydride (BPDA), and the diamine component is diaminodiphenylsulfone (DAS) and diaminobis (trifluoromethyl) biphenyl (TFMB). And a polycondensate of a material component which is a silicon-containing diamine (more preferably, a weight average molecular weight of 110,000 to 250,000 and a solid content of 10 to 25% by mass).

(4) A polycondensate of a material component in which the acid dianhydride component is pyromellitic dianhydride (PMDA) and the diamine component is diaminodiphenyl sulfone (DAS) (more preferably, the weight average molecular weight is 110,000 to 140, 000, solid content 10-25% by mass)
(5) A polycondensate of a material component in which the acid dianhydride component is pyromellitic dianhydride (PMDA) and the diamine component is diaminodiphenylsulfone (DAS) and a silicon-containing diamine (more preferably, the weight average molecular weight is 110, 000 to 230,000, solid content 10 to 25% by mass)
(6) Polycondensation of material components in which the acid dianhydride component is pyromellitic acid dianhydride (PMDA) and the diamine component is diaminodiphenyl sulfone (DAS), diaminobis (trifluoromethyl) biphenyl (TFMB) and silicon-containing diamine. (Preferably, weight average molecular weight 110,000 to 250,000, solid content content 10 to 25% by mass)

(7) A polycondensate of a material component in which the acid dianhydride component is biphenyltetracarboxylic dianhydride (BPDA) and the diamine component is diaminodiphenylsulfone (DAS) (more preferably, the weight average molecular weight is 110,000 to 120). 000, solid content 20-25% by mass)
(8) A polycondensate of a material component (more preferably, a weight average molecular weight of 110) in which the acid dianhydride component is biphenyltetracarboxylic dianhydride (BPDA) and the diamine component is diaminodiphenylsulfone (DAS) and a silicon-containing diamine. 000 to 160,000, solid content 10 to 25% by mass)
(9) Weight of material components in which the acid dianhydride component is biphenyltetracarboxylic dianhydride (BPDA) and the diamine component is diaminodiphenylsulfone (DAS), diaminobis (trifluoromethyl) biphenyl (TFMB) and silicon-containing diamine. Condensate (more preferably, weight average molecular weight 110,000 to 240,000, solid content 10 to 25% by mass)

In the material components of the polycondensate of the above (1) to (9), the silicon-containing diamine is preferably a diamino (poly) siloxane represented by the above formula (3a) (preferably a number average molecular weight of 500 to 12,000). ), More preferably a double-terminal amine-modified methylphenyl silicone oil.

[Manufacturing of polyimide precursor]
The polyimide precursor of the present embodiment can be synthesized by subjecting a polycondensation component containing an acid dianhydride component and a diamine component to a polycondensation reaction. In a preferred embodiment, the polycondensation component comprises an acid dianhydride component and a diamine component. The polycondensation reaction is preferably carried out in a suitable solvent. Specifically, for example, a method in which a predetermined amount of diamine component is dissolved in a solvent, a predetermined amount of acid dianhydride is added to the obtained diamine solution, and the mixture is stirred.

The molar ratio of the acid dianhydride component to the diamine component when synthesizing the polyimide precursor is determined from the viewpoint of increasing the molecular weight of the polyimide precursor resin and the slit coating characteristics of the resin composition. Acid dianhydride: diamine = 100 : It is preferably in the range of 90 to 100: 110 (0.99 to 1.10 parts of diamine with respect to 1 mol of acid dianhydride), and is preferably 100: 95 to 100: 105 (1 mol of acid dianhydride). It is more preferable that the range is 0.95 to 1.05 mol of diamine with respect to the portion.

The molecular weight of the polyimide precursor can be controlled by adjusting the types of the acid dianhydride component and the diamine component, adjusting the ratio of the acid dianhydride component and the diamine component, adding an end-capping agent, adjusting the reaction conditions, etc. Is. The closer the ratio of the acid dianhydride component to the diamine component is to 1: 1 and the smaller the amount of the end-capping agent used, the higher the molecular weight of the polyimide precursor can be. It is recommended to use high-purity products as the acid dianhydride component and the diamine component. The purity is preferably 98% by mass or more, more preferably 99% by mass or more, and further preferably 99.5% by mass or more. Further, the purity can be increased by reducing the water content in the acid dianhydride component and the diamine component. When a plurality of types of acid dianhydride components or diamine components are used in combination, it is sufficient that the acid dianhydride components or diamine components as a whole have the above purity, but all types of acid dianhydrides to be used It is preferable that the component and the diamine component each have the above-mentioned purity.

式中、Ｒ₁₂＝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、Ｒ₁₂＝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、フェノール、ｏ−クレゾール、ｍ−クレゾール、ｐ−クレゾール、２，３−キシレノール、２，４−キシレノール、２，５−キシレノール、２，６−キシレノール、３，４−キシレノール、３，５−キシレノール等が：前記エーテル及びグリコール系溶媒として、例えば、１，２−ジメトキシエタン、ビス（２−メトキシエチル）エーテル、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］エーテル、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。これらの溶媒は、単独で又は２種類以上混合して用いてもよい。The solvent for the reaction is not particularly limited as long as it can dissolve the acid dianhydride component, the diamine component, and the generated polyimide precursor, and can obtain a high molecular weight polymer. Specific examples of such a solvent include aprotic solvents, phenolic solvents, ether and glycol solvents and the like. Specific examples of these include, as the aprotic solvent, for example, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N-methyl. Caprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, the following general formula (4):

In the formula, Equamid M100 represented by R ₁₂ = methyl group (trade name: manufactured by Idemitsu Kosan Co., Ltd.), Equamid B100 represented by R ₁₂ = n-butyl group (trade name: manufactured by Idemitsu Kosan Co., Ltd.), etc. Amide-based solvent; lactone-based solvent such as γ-butyrolactone and γ-valerolactone; phosphorus-containing amide-based solvent such as hexamethylphosphoric amide and hexamethylphosphintriamide; sulfur-containing solvent such as dimethylsulfone, dimethylsulfoxide and sulfolane Solvents: Ketone solvents such as cyclohexanone and methylcyclohexanone; Tertiary amine solvents such as picolin and pyridine; Ester solvents such as acetic acid (2-methoxy-1-methylethyl): As the phenolic solvent, For example, phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5- Xylenol and the like: Examples of the ether and glycol-based solvent include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, and bis [2- (2- (2-)2-. Examples thereof include methoxyethoxy) ethyl] ether, tetrahydrofuran, 1,4-dioxane and the like. These solvents may be used alone or in combination of two or more.

The boiling point of the solvent used for synthesizing the polyimide precursor at normal pressure is preferably 60 to 300 ° C, more preferably 140 to 280 ° C, and particularly preferably 170 to 270 ° C. If the boiling point of the solvent is higher than 300 ° C., a drying step is required for a long time. On the other hand, if the boiling point of the solvent is lower than 60 ° C., roughening may occur on the surface of the resin film, air bubbles may be mixed into the resin film, and the like, and a uniform film may not be obtained during the drying step. In particular, it is preferable to use a solvent having a boiling point of 170 to 270 ° C. and / or a vapor pressure of 250 Pa or less at 20 ° C. from the viewpoint of solubility and edge repelling during coating. More specifically, one or more selected from the group consisting of N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), and the compound represented by the general formula (4) is preferable.

The water content in the solvent is preferably, for example, 3,000 mass ppm or less from the viewpoint of good progress of the polycondensation reaction. Further, in the resin composition according to the present embodiment, the content of molecules having a molecular weight of less than 1,000 is preferably less than 5% by mass. It is considered that the reason why molecules having a molecular weight of less than 1,000 are present in the resin composition is that the water content of the solvent and raw materials (acid dianhydride, diamine) used at the time of synthesis is involved. That is, it is considered that the acid anhydride group of some acid dianhydride monomers is hydrolyzed by water to become a carboxyl group, which remains in a low molecular weight state without increasing the molecular weight. Therefore, it is preferable that the amount of water in the solvent used for the above-mentioned polycondensation reaction is small. The water content of the solvent is preferably 3,000 mass ppm or less, and more preferably 1,000 mass ppm or less. Similarly, the amount of water contained in the raw material is preferably 3,000 mass ppm or less, and more preferably 1,000 mass ppm or less.

The water content of the solvent is the grade of the solvent used (dehydration grade, general-purpose grade, etc.), solvent container (bottle, 18L can, canister can, etc.), solvent storage state (presence or absence of rare gas filling, etc.), from opening to use. (Whether to use immediately after opening or after a lapse of time after opening, etc.) is considered to be involved. In addition, it is considered that the replacement of rare gas in the reactor before synthesis and the presence or absence of rare gas flow during synthesis are also involved. Therefore, when synthesizing the polyimide precursor, it is recommended to use a high-purity product as a 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. Will be done.

When each polycondensation component is dissolved in a solvent, it may be heated if necessary. From the viewpoint of obtaining a polyimide precursor having a high degree of polymerization, a preferable reaction temperature at the time of synthesizing the polyimide precursor can be 0 ° C. to 120 ° C., 40 ° C. to 100 ° C., or 60 to 100 ° C., which is preferable polymerization. Examples of the time include 1 to 100 hours or 2 to 10 hours. When the polymerization time is 1 hour or more, a polyimide precursor having a uniform degree of polymerization can be obtained, and when the polymerization time is 100 hours or less, a polyimide precursor having a high degree of polymerization can be obtained.

The resin composition of the present embodiment may be a combination of a polyimide precursor having a structure represented by the formula (1) and another additional polyimide precursor, but the mass ratio of the additional polyimide precursor. Is 30% by mass or less with respect to the total amount of the polyimide precursor in the resin composition from the viewpoint of reducing the yellowness (YI) of the cured product (for example, the polyimide film) and the oxygen dependence of the total light transmittance. It is preferably 10% by mass or less, and more preferably 10% by mass or less.

In a preferred embodiment of the present embodiment, the polyimide precursor may be partially imidized. The partially imidized polyimide precursor can improve the viscosity stability of the resin composition when stored at room temperature. In this case, the imidization ratio is preferably 5% or more, more preferably 8% or more, preferably 8% or more, from the viewpoint of balancing the solubility of the polyimide precursor in the resin composition and the storage stability of the solution. Is 80% or less, more preferably 70% or less, still more preferably 50% or less. This partial imidization is obtained by heating the polyimide precursor to dehydrate and ring closure. This heating can be carried out at a temperature of preferably 120 to 200 ° C., more preferably 150 to 180 ° C., preferably for 15 minutes to 20 hours, more preferably 30 minutes to 10 hours. Further, N, N-dimethylformamide dimethylacetal or N, N-dimethylformamide diethylacetal is added to the polyamic acid obtained by the above reaction and heated to esterify a part or all of the carboxylic acid, and then esterify the carboxylic acid. By using it as the polyimide precursor in the present embodiment, it is possible to obtain a resin composition having improved viscosity stability when stored at room temperature. In addition to these ester-modified polyamic acids, the above-mentioned acid dianhydride component is sequentially reacted with 1 equivalent of a monohydric alcohol with respect to the acid anhydride group and a dehydration condensing agent such as thionyl chloride or dicyclohexylcarbodiimide. After that, it can also be obtained by a method of condensation reaction with a diamine component.

In one aspect, the resin composition comprises a solvent. The solvent is preferably one in which the solubility of the polyimide precursor is good and the solution viscosity of the resin composition can be appropriately controlled, and the reaction solvent of the polyimide precursor can be used as the solvent of the composition. Among them, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), the compound represented by the general formula (4) and the like are preferable. Specific examples of the solvent composition include N-methyl-2-pyrrolidone (NMP) alone or a mixed solvent of N-methyl-2-pyrrolidone (NMP) and γ-butyrolactone (GBL) (for example, NMP: GBL (mass)). Ratio) = 10:90 to 90:10) and the like.

[Additional ingredients]
The resin composition of the present embodiment may contain an additional component in addition to (a) a polyimide precursor and (b) a solvent. Additional components include (c) surfactants, (d) alkoxysilane compounds, and the like.

((C) Surfactant)
By adding a surfactant to the resin composition of the present embodiment, the coatability of the resin composition can be improved. Specifically, it is possible to prevent the occurrence of streaks in the coating film.
Examples of such surfactants include silicone-based surfactants, fluorine-based surfactants, and other nonionic surfactants. Examples of these examples include, as silicone-based surfactants, for example, organosiloxane polymers KF-640, 642, 643, KP341, X-70-092, X-70-093, (trade name, Shin-Etsu Chemical Industry Co., Ltd.). , SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (above, trade name, manufactured by Toray Dow Corning Silicone), SILWET L-77 , L-7001, FZ-2105, FZ-2120, FZ-2154, FZ-2164, FZ-2166, L-7604 (trade name, manufactured by Nippon Unicar Co., Ltd.), DBE-814, DBE-224, DBE- 621, CMS-626, CMS-222, KF-352A, KF-354L, KF-355A, KF-6020, DBE-821, DBE-712 (Gelest), BYK-307, BYK-310, BYK-378, BYK -333 (trade name, manufactured by Big Chemie Japan), Granol (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), etc .; as fluorosurfactants, for example, Megafuck F171, F173, R-08 (Dainippon Ink and Chemicals) Industrial Co., Ltd., trade name), Florard FC4430, FC4432 (Sumitomo 3M Co., Ltd., trade name), etc .; Other nonionic surfactants include, for example, polyoxyethylene uralyl ether, polyoxyethylene stearyl ether, etc. Examples thereof include polyoxyethylene oleyl ether and polyoxyethylene octylphenol ether.

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

(D) Alkoxysilane Compound When the polyimide film obtained from the resin composition according to the present embodiment is used for a flexible substrate or the like, the resin composition is obtained from the viewpoint of obtaining good adhesion between the support and the polyimide film in the manufacturing process. The product can contain 0.01 to 20 parts by mass of the alkoxysilane compound with respect to 100 parts by mass of the (a) polyimide precursor. When the content of the alkoxysilane compound with respect to 100 parts by mass of the polyimide precursor is 0.01 parts by mass or more, good adhesion between the support and the polyimide film can be obtained. Further, the content of the alkoxysilane compound is preferably 20 parts by mass or less from the viewpoint of storage stability of the resin composition. The content of the alkoxysilane compound is more preferably 0.02 to 15 parts by mass, further preferably 0.05 to 10 parts by mass, and 0.1 to 1 parts by mass with respect to 100 parts by mass of the polyimide precursor. It is particularly preferably 8 parts by mass.
Further, by using the alkoxysilane compound as an additive of the resin composition according to the present embodiment, in addition to the above-mentioned improvement of the adhesiveness, the coatability (suppression of yellowing) of the resin composition can be improved and obtained. It is also possible to reduce the dependence of the yellowness (YI) value of the cured film to be oxygen concentration during curing.

Examples of the alkoxysilane compound include 3-ureidopropyltriethoxysilane, bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane. γ-Aminopropyltripropoxysilane, γ-aminopropyltributoxysilane, γ-aminoethyltriethoxysilane, γ-aminoethyltripropoxysilane, γ-aminoethyltributoxysilane, γ-aminobutyltriethoxysilane, γ- Aminobutyltrimethoxysilane, γ-aminobutyltripropoxysilane, γ-aminobutyltributoxysilane, phenylsilanetriol, trimethoxyphenylsilane, trimethoxy (p-tolyl) silane, diphenylsilanediol, dimethoxydiphenylsilane, diethoxydiphenyl Examples thereof include silane, dimethoxydi-p-tolylsilane, triphenylsilanol, and alkoxysilane compounds represented by each of the following structures, and it is preferable to use one or more selected from these.

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

When the solvent used when synthesizing the (a) polyimide precursor and the solvent contained in (b) the resin composition are the same, the synthesized polyimide precursor solution can be used as it is as the resin composition. .. If necessary, (a) a solvent and one or more additional components are added to the polyimide precursor in a temperature range of room temperature (25 ° C.) to 80 ° C., and the mixture is stirred and mixed. , May be used as a resin composition. For this stirring and mixing, an appropriate device such as a three-one motor (manufactured by Shinto Chemical Co., Ltd.) equipped with a stirring blade, a rotation / revolution mixer, or the like can be used. Further, heat of 40 to 100 ° C. may be applied if necessary.

On the other hand, if (a) the solvent used when synthesizing the polyimide precursor and (b) the solvent contained in the resin composition are different, the solvent in the synthesized polyimide precursor solution is, for example, reprecipitated. After removing (a) the polyimide precursor by an appropriate method such as solvent distillation, (b) a solvent and, if necessary, additional components are added in a temperature range of room temperature to 80 ° C. , The resin composition may be prepared by stirring and mixing.

After preparing the resin composition as described above, by heating the composition at, for example, 130 to 200 ° C. for, for example, 5 minutes to 2 hours, a part of the polyimide precursor is dehydrated to the extent that the polymer does not precipitate. It may be transformed into. Here, the imidization rate can be controlled by controlling the heating temperature and the heating time. As described above, the partially imidized polyimide precursor can improve the viscosity stability of the resin composition when stored at room temperature.

The solution viscosity of the resin composition is preferably 500 to 100,000 mPa · s, more preferably 1,000 to 50,000 mPa · s, and particularly 3,000 to 20,000 mPa · s from the viewpoint of slit coating performance. preferable. Specifically, it is preferably 500 mPa · s or more, more preferably 1,000 mPa · s or more, and further preferably 3,000 mPa · s or more in terms of preventing liquid leakage from the slit nozzle. Further, the slit nozzle is less likely to be clogged, and is preferably 100,000 mPa · s or less, more preferably 50,000 mPa · s or less, and further preferably 20,000 mPa · s or less. Further, from the viewpoint of the viscosity at the time of synthesis, if the solution viscosity of the resin composition is higher than 200,000 mPa · s, there may be a problem that stirring at the time of synthesis becomes difficult. However, even if the solution becomes highly viscous during synthesis, it is possible to obtain a resin composition having a viscosity that is easy to handle by adding a solvent and stirring after the reaction is completed. The solution viscosity of the resin composition in the present disclosure is a value measured at 23 ° C. using an E-type viscometer (for example, VISCONICEHD, manufactured by Toki Sangyo).

The water content of the resin composition according to this embodiment is preferably 3,000 mass ppm or less. The water content of the resin composition is preferably 2,500 mass ppm or less, preferably 2,000 mass ppm or less, and preferably 1,500 mass ppm or less from the viewpoint of viscosity stability when the resin composition is stored. , 1,000 mass ppm or less, more preferably 500 mass ppm or less, preferably 300 mass ppm or less, and preferably 100 mass ppm or less.

<Manufacturing method of polyimide film>
This embodiment is
A coating step of applying the resin composition of the present embodiment on the surface of the support, and
A film forming step of heating the resin composition to form a polyimide film,
Provided is a method for producing a polyimide film, which comprises a peeling step of peeling a polyimide film from a support.

[Applying process]
In the coating step, the resin composition is coated on the surface of the support. The support is not particularly limited as long as it has heat resistance at the heating temperature in the subsequent film forming step (heating step) and has good peelability in the peeling step. For example, glass (eg, alkali-free glass) substrate; silicon wafer; PET (polyethylene terephthalate), OPP (stretched polypropylene), polyethylene glycol terephthalate, polyethylene glycol naphthalate, polycarbonate, polyimide, polyamideimide, polyetherimide, polyetherether. Resin substrates such as ketone, polyether sulfone, polyphenylene sulfone, and polyphenylene sulfide; metal substrates such as stainless steel, alumina, copper, and nickel are used.

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

As a coating method, generally, a doctor blade knife coater, an air knife coater, a roll coater, a rotary coater, a flow coater, a die coater, a bar coater, etc., a spin coat, a spray coat, a dip coat, etc. are applied; screen printing. And printing techniques typified by gravure printing and the like, the resin composition of this embodiment is particularly useful for slit coating (that is, coating with a slit coater). The coating thickness should be appropriately adjusted according to the desired thickness of the polyimide film and the content of the polyimide precursor in the resin composition, but is preferably about 1 to 1,000 μm. Although the coating step may be carried out at room temperature, the resin composition may be heated in the range of, for example, 40 to 80 ° C. for the purpose of lowering the viscosity and improving workability.

[Arbitrary drying process]
The drying step may be performed following the coating step, or the drying step may be omitted and the process may be directly advanced to the next film forming step (heating step). The drying step is performed for the purpose of removing the organic solvent in the resin composition. When performing the drying step, for example, an appropriate device such as a hot plate, a box-type dryer, or a conveyor-type dryer can be used. The drying step is preferably carried out at 80 to 200 ° C., more preferably 100 to 150 ° C. The implementation time of the drying step is preferably 1 minute to 10 hours, and more preferably 3 minutes to 1 hour. As described above, a coating film containing a polyimide precursor is formed on the support.

[Film formation process]
Subsequently, a film forming step (heating step) is performed. The heating step is a step of removing the organic solvent remaining in the coating film in the above-mentioned drying step and advancing the imidization reaction of the polyimide precursor in the coating film to obtain a polyimide film. This heating step can be performed using an apparatus such as an inert gas oven, a hot plate, a box-type dryer, or a conveyor-type dryer. This step may be carried out at the same time as the drying step, or both steps may be carried out sequentially.

The heating step may be carried out in an air atmosphere, but from the viewpoint of safety, good transparency of the obtained polyimide film, low thickness direction retardation (Rth) and low yellowness (YI), an inert gas is obtained. It is recommended to do it in an atmosphere. Examples of the inert gas include nitrogen, argon and the like. The heating temperature may be appropriately set according to the type of the polyimide precursor and the type of the solvent in the resin composition, but is preferably 250 ° C to 550 ° C, more preferably 300 to 450 ° C. If the temperature is 250 ° C. or higher, imidization proceeds satisfactorily, and if the temperature is 550 ° C. or lower, inconveniences such as deterioration of transparency and heat resistance of the obtained polyimide film can be avoided. The heating time is preferably about 0.1 to 10 hours.

In the present embodiment, the oxygen concentration in the ambient atmosphere in the heating step is preferably 2,000 mass ppm or less, preferably 100 mass ppm or less, from the viewpoint of the transparency and yellowness (YI) value of the obtained polyimide film. More preferably, 10 mass ppm or less is further preferable. By heating in an atmosphere having an oxygen concentration of 2,000 mass ppm or less, the yellowness (YI) value of the obtained polyimide film can be reduced to 30 or less.

[Peeling process]
Next, in the peeling step, the polyimide film on the support is cooled to, for example, about room temperature to about 50 ° C. and then peeled off. Examples of the peeling step include the following aspects (1) to (4).

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

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

Among these peeling methods, the method (1) or (2) is appropriate from the viewpoint of the difference in refractive index between the front and back surfaces of the obtained polyimide film, the yellowness (YI) value, and the elongation, and the obtained polyimide film From the viewpoint of the difference in refractive index between the front and back surfaces, it is more appropriate to perform the method (1), that is, the irradiation step of irradiating the laser from the support side prior to the peeling step.
When copper is used as the support in the method (3), the yellowness (YI) value of the obtained polyimide film tends to be large and the elongation tends to be small. This is considered to be the effect of copper ions.

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

<Use of polyimide film>
The polyimide film obtained from the polyimide precursor according to the present embodiment can be applied as, for example, a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, etc., and is particularly used in the manufacture of flexible devices such as TFT substrates and color filter substrates. , Can be suitably used as a touch panel substrate. Here, examples of the flexible device to which the polyimide film according to the present embodiment can be applied include a TFT device for a flexible display, a flexible solar cell, a flexible touch panel, a flexible lighting, a flexible battery, a flexible printed substrate, a flexible color filter, and a smartphone. A surface cover lens for facing can be mentioned.

The step of forming a TFT on a flexible substrate using a polyimide film is typically carried out at a temperature in a wide range of 150 to 650 ° C. Specifically, when manufacturing a TFT device using amorphous silicon, a process temperature of 250 ° C. to 350 ° C. is generally required, and the polyimide film of the present embodiment needs to be able to withstand that temperature. Specifically, it is necessary to appropriately select a polymer structure having a glass transition temperature equal to or higher than the process temperature and a thermal decomposition start temperature.

When manufacturing a TFT device using a metal oxide semiconductor (IGZO or the like), a process temperature of 320 ° C. to 400 ° C. is generally required, and the polyimide film of the present embodiment must be able to withstand that temperature. Therefore, it is necessary to appropriately select a polymer structure having a glass transition temperature equal to or higher than the maximum temperature of the TFT fabrication process and a thermal decomposition start temperature.

When manufacturing a TFT device using low temperature polysilicon (LTPS), a process temperature of 380 ° C. to 520 ° C. is generally required, and the polyimide film of the present embodiment needs to be able to withstand that temperature. , It is necessary to appropriately select and have a glass transition temperature equal to or higher than the maximum temperature of the TFT fabrication process and a thermal decomposition start temperature.
On the other hand, due to these thermal histories, the optical properties of the polyimide film (particularly, light transmittance, retardation properties and yellowness) tend to decrease as they are exposed to high temperature processes. However, the polyimide obtained from the polyimide precursor of the present embodiment has good optical properties even after undergoing thermal history.

Hereinafter, as an application example of the resin composition and the polyimide film of the present embodiment, a display, a laminate, and a method for producing these will be described.

[Display and its manufacturing method]
The present embodiment also provides a flexible device containing a polyimide film which is a cured product of the resin composition of the present embodiment. A preferred example of the flexible device is a flexible display. In one aspect, the polyimide film is excellent in optical properties (eg Rth and / or yellowness). Therefore, in a preferred embodiment, the polyimide film is arranged at a position (specifically, a screen portion of the flexible display) that is visible when the display is observed from the outside.

This embodiment is
A coating step of coating (preferably slit coating) the resin composition of the present embodiment on the surface of a support such as a glass substrate.
A film forming step of heating the resin composition to form a polyimide film,
The element forming process of forming an element on the polyimide film and
Also provided is a method for manufacturing a display, which comprises a peeling step of peeling a polyimide film on which an element is formed from a support.

[Manufacturing method of flexible organic EL display]
FIG. 1 is a diagram showing a structure above a polyimide substrate of a top emission type flexible organic EL display as an example of a display provided in one aspect of the present invention. Explaining the organic EL structure portion 25 of FIG. 1, for example, an organic EL element 250a that emits red light, an organic EL element 250b that emits green light, and an organic EL element 250c that emits blue light are in a matrix shape as one unit. The light emitting region of each organic EL element is defined by the partition wall (bank) 251. Each organic EL element is composed of a lower electrode (anode) 252, a hole transport layer 253, a light emitting layer 254, and an upper electrode (cathode) 255. Further, on the lower layer 2a showing the CVD multilayer film (multi-barrier layer) made of silicon nitride (SiN) or silicon oxide (SiO), TFT256 (low temperature polysilicon (LTPS)) for driving the organic EL element is formed. A plurality of metal oxide semiconductors (selected from IGZO and the like), an interlayer insulating film 258 provided with contact holes 257, and a plurality of lower electrodes 259 are provided. The organic EL element is enclosed by a sealing substrate 2b, and a hollow portion 261 is formed between each organic EL element and the sealing substrate 2b.

In the flexible organic EL display manufacturing process, a polyimide film is produced on a glass substrate support, and the organic EL substrate shown in FIG. 1 is manufactured on the polyimide film, a sealing substrate manufacturing process, and assembly in which both substrates are bonded together. It includes a step and a peeling step of peeling the organic EL display produced on the polyimide film from the glass substrate support.
A well-known manufacturing process can be applied to the organic EL substrate manufacturing process, the sealing substrate manufacturing process, and the assembling process. An example is given below, but the present invention is not limited to this. Further, the peeling step may be the same as the peeling step of the polyimide film described above.

With reference to FIG. 1, for example, first, a polyimide film of the present disclosure is prepared on a glass substrate support by the method described above, and silicon nitride (SiN) and silicon oxide (SiO) are formed on the polyimide film by a CVD method or a sputtering method. A multi-barrier layer (lower substrate 2a in FIG. 1) having a multi-layer structure of the above is produced, and a metal wiring layer for driving the TFT is produced on the upper portion by using a photoresist or the like. An active buffer layer such as SiO is produced on the upper part by a CVD method, and a TFT device (TFT256 in FIG. 1) such as a metal oxide semiconductor (IGZO) and low temperature polysilicon (LTPS) is produced on the upper part. After manufacturing the TFT substrate for a flexible display, an interlayer insulating film 258 having a contact hole 257 is formed of a photosensitive acrylic resin or the like. An ITO film is formed by a sputtering method or the like, and a lower electrode 259 is formed so as to form a pair with the TFT.

Next, after forming the partition wall (bank) 251 with photosensitive polyimide or the like, the hole transport layer 253 and the light emitting layer 254 are formed in each space partitioned by the partition wall. Further, the upper electrode (cathode) 255 is formed so as to cover the light emitting layer 254 and the partition wall (bank) 251. After that, using a fine metal mask or the like as a mask, an organic EL material that emits red light (corresponding to the organic EL element 250a that emits red light in FIG. 1) and an organic EL material that emits green light (in FIG. 1). (Corresponding to the organic EL element 250b that emits green light) and the organic EL material that emits blue light (corresponding to the organic EL element 250c that emits blue light in FIG. 1) are deposited by a known method. Then, an organic EL substrate is produced, and after sealing with a sealing film or the like (sealing substrate 2b in FIG. 1), the device above the polyimide substrate is peeled from the glass substrate support by a known peeling method such as laser peeling. By doing so, a top emission type flexible organic EL display is produced. When the polyimide of the present embodiment is used, a see-through type flexible organic EL display is produced. Further, a bottom emission type flexible organic EL display may be produced by a known method.

[Manufacturing method of flexible liquid crystal display]
A flexible liquid crystal display can be manufactured using the polyimide film of the present embodiment. As a specific manufacturing method, a polyimide film made of the present invention is prepared on a glass substrate support by the above-mentioned method, and for example, amorphous silicon, a metal oxide semiconductor (IGZO, etc.), or, using the above-mentioned method. A TFT substrate made of low-temperature polysilicon is manufactured. Separately, a polyimide film is prepared on the glass substrate support according to the coating step and the film forming step of the present embodiment, and a color resist or the like is used according to a known method to provide a color filter glass substrate provided with the polyimide film. CF substrate) is manufactured. A sealing material composed of a thermosetting epoxy resin or the like is applied to one of the TFT substrate and the CF substrate by screen printing in a frame-like pattern lacking a liquid crystal injection port portion, and the other substrate is coated with a liquid crystal layer. A spherical spacer having a diameter corresponding to the thickness and made of plastic or silica is sprayed.

Next, the TFT substrate and the CF substrate are bonded together to cure the sealing material.
Finally, the liquid crystal material is injected into the space surrounded by the TFT substrate, the CF substrate, and the sealing material by the decompression method, a thermosetting resin is applied to the liquid crystal injection port, and the liquid crystal material is sealed by heating to form a liquid crystal layer. To form. Finally, a flexible liquid crystal display can be manufactured by peeling the glass substrate on the CF side and the glass substrate on the TFT side at the interface between the polyimide film and the glass substrate by a laser peeling method or the like.

[Manufacturing method of laminate]
This embodiment is
A coating step of applying the resin composition of the present embodiment on the surface of the support, and
A film forming step of heating the resin composition to form a polyimide film,
Also provided is a method for manufacturing a laminate including an element forming step of forming an element on a polyimide film.

Examples of the element in the laminated body include those exemplified as the above-mentioned flexible device (for example, a flexible display). As the support, for example, a glass substrate is used. The preferable specific procedure of the coating step and the film forming step is the same as that described above with respect to the above-mentioned method for producing a polyimide film. Further, in the element forming step, the above element is formed on the polyimide film as a flexible substrate formed on the support. After that, the polyimide film and the element may be peeled off from the support in an optional peeling step.

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

<Weight average molecular weight>
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) under the following conditions.

As solvents, NMP (manufactured by Wako Pure Chemical Industries, Ltd., for high performance liquid chromatography, 24.8 mmol / L lithium bromide monohydrate (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.5%) immediately before measurement) and 63. .2 mmol / L phosphoric acid (manufactured by Wako Pure Chemical Industries, Ltd., for high performance liquid chromatograph) was added and dissolved) was used. The calibration curve for calculating the weight average molecular weight was prepared using standard polystyrene (manufactured by Toso Co., Ltd.).
Column: Shodex KD-806M (manufactured by Showa Denko KK)
Flow velocity: 1.0 mL / min Column temperature: 40 ° C
Pump: PU-2080Plus (manufactured by JASCO)
Detectors: RI-2031Plus (RI: differential refractometer, manufactured by JASCO) and UV-2075Plus (UV-VIS: ultraviolet-visible absorptiometer, manufactured by JASCO)

<Shear velocity dependence (TI) evaluation>
The viscosity of the resin composition prepared in Examples and Comparative Examples was measured at 23 ° C. using a viscometer with a temperature controller (TVE-35H manufactured by Toki Sangyo Kikai Co., Ltd.) to determine the viscosity of the resin composition to be measured. The shear rate dependence was evaluated by measuring using a measurable rotation speed and a cone rotor.
Specifically, the viscosity ηa (mPa · s) at the measurement rotation speed a (rpm) and the viscosity ηb (mPa · s) at the measurement rotation speed b (rpm) are measured (here, a * 10 = b). Yes), the TI expressed by the following formula was obtained.
TI = ηa / ηb
Specific examples of the measurable rotation speed are, for example, 0.5, 1,2.5, 5, 10, 20, 50, 100 rpm.
Specific examples of measurable cone rotors are, for example, 1 ° 34'(corn rotor angle) × R24 (corn rotor diameter), 1 ° 34' × R12, 0.8 ° × R24, 0.8 ° × R12, 3 ° × R24, 3 ° × R12, 3 ° × R17.65, 3 ° × R14, 3 ° × R12, 3 ° × R9.7.

<Coating evaluation>
The resin compositions prepared in Examples and Comparative Examples were applied to a 300 mm * 300 mm glass substrate using a slit coater (manufactured by SCREEN Finetech Solutions Co., Ltd.) with a coating area of 295 mm * 295 mm, and coating evaluation was performed. ..

(Slit nozzle evaluation)
The resin compositions (varnishes) prepared in Examples and Comparative Examples were filled in the nozzles of the slit coater, evaluated according to the following criteria, and listed in the table.
After starting the varnish discharge from the nozzle and stopping the discharge, the varnish drips from the slit nozzle: Liquid leakage The varnish is not discharged from the nozzle: Clogged Liquid leaks, can be coated without clogging: No problem

(Coat gap)
The resin composition (varnish) prepared in Examples and Comparative Examples has a film thickness of 10 μm after imidization (heating at 100 ° C. for 1 hour and then at 400 ° C. for 30 minutes at an oxygen concentration of 10 mass ppm or less). It was coated on a glass substrate (coating speed 100 mm / sec) so as to be. The court gap setting values of the slit coater at that time are shown in the table.

(Edge evaluation)
The resin compositions prepared in Examples and Comparative Examples were coated on a glass substrate, transferred to a drying oven, heated at 100 ° C. for 1 hour, and then the edges of the coating film were observed at 10 times using an optical microscope. It was evaluated according to the following criteria.
Further, the edge bead (swelling of the edge portion) of the coating film was measured using a stylus type step meter (P-15: manufactured by KLA Tencor), and evaluated according to the following criteria.
Microscopic observation of the edge part observes dripping with a width of 0.5 mm or more: Dripping The thickness of the bead is 30% or more of the coating film thickness in the film thickness measurement of the edge part: Bead dripping, edge abnormality None: No problem

(Slit coat is possible)
The (slit nozzle evaluation), (coat gap), and (edge evaluation) were evaluated according to the following criteria and listed in the table.
In the composition using the polyimide precursor having a predetermined weight average molecular weight in each Example and Comparative Example, all the following evaluation results are satisfied with at least one solid content content in the range of 7 to 28% by mass: Yes In the composition using the polyimide precursor having the predetermined polymerization average molecular weight of each Example and Comparative Example, in the range of the solid content content of 7 to 28% by mass, all the following evaluation results may not be satisfied: Impossible Slit nozzle Evaluation: No problem Coat gap: 50 μm or more Edge evaluation: No problem

<Cured film film thickness uniformity (standard deviation)>
In the above <coating evaluation> (coat gap), the polyimide film according to the examples and comparative examples prepared on the glass substrate (that is, the polyimide film formed on the glass substrate of 300 mm * 300 mm at 295 mm * 295 mm) was used. Using a glass substrate on which a polyimide film is formed, the film thickness is 20 mm apart from the center of the coated surface toward the end faces of MD (that is, the direction perpendicular to the slit coat) and TD (the direction perpendicular to MD). (Therefore, the outermost end is at a position 7.5 mm from the end face) (MD 15 points, TD 15 points, total 30 points). A contact-type profilometer was used to measure the film thickness. From the results, the film thickness uniformity of the polyimide film (standard deviation of the film thickness at 30 points) was calculated and evaluated according to the following criteria.
Good: In-plane film thickness uniformity (3 sigma) is 1.0 μm or less Possible: In-plane film thickness uniformity (3 sigma) is more than 1.0 μm and 2.0 μm or less Defective: In-plane film thickness uniformity (3 sigma) Is over 2.0 μm

<Elongation of cured film>
The resin compositions prepared in Examples and Comparative Examples were spin-coated on a 6-inch silicon wafer substrate having an aluminum-deposited layer on the surface so that the film thickness was 10 μm after curing, and prebaked at 100 ° C. for 6 minutes. .. After that, using a vertical curing furnace (manufactured by Koyo Lindbergh Co., Ltd., model name VF-2000B), the oxygen concentration in the refrigerator was adjusted to 10 mass ppm or less, and heat curing treatment was performed at 400 ° C. for 30 minutes. A wafer on which a polyimide film was formed was produced. Next, a dicing saw (DAD 3350 manufactured by DISCO Corporation) was used to make a 3 mm wide cut in the polyimide film of the wafer, and then the wafer was immersed in a dilute aqueous hydrochloric acid solution overnight to peel off the film piece and dried. This was cut to a length of 50 mm and used as a sample.

The elongation of the above sample was measured using TENSILON (UTM-II-20 manufactured by Orientec Co., Ltd.) at a test speed of 40 mm / min and an initial load of 0.5 fs. It was evaluated according to the following criteria and listed in the table.
Excellent: 40% or more Good: 20% or more, less than 40% Possible: Less than 20%

<Hardened film haze>
In the above <coating evaluation> (coat gap), the polyimide films of Examples and Comparative Examples prepared on a glass substrate were used.

The obtained sample was measured for haze (converted to a film thickness of 10 μm) in accordance with the JIS K7105 transparency test method using an SC-3H type haze meter manufactured by Suga Test Instruments Co., Ltd. The measurement results were evaluated according to the following criteria and listed in the table.
Excellent: Haze is 0.5 or less Good: Haze is greater than 0.5 and 1.5 or less Possible: Haze is greater than 1.5

<Hardened film yellowness (YI))>
In the above <coating evaluation> (coat gap), the polyimide films of Examples and Comparative Examples prepared on a glass substrate were used. With respect to the obtained sample, the yellowness (YI) value (converted to a film thickness of 10 μm) was measured using a D65 light source manufactured by Nippon Denshoku Kogyo Co., Ltd. (Spectrophotometer: SE600). The results are listed in the table.

<Hardened film Rth (retalysis, retardation in the thickness direction)>
In the above <coating evaluation> (coat gap), the polyimide films of Examples and Comparative Examples prepared on a glass substrate were used. The obtained sample was measured for Rth (converted to a film thickness of 10 μm) using a phase difference birefringence measuring device (KOBRA-WR manufactured by Oji Measuring Instruments Co., Ltd.). The wavelength of the measurement light was 589 nm. The results are listed in the table.

<Comparative Example 1-1>
NMP (812 g) was added to a 3 L separable flask with a stirring rod while introducing nitrogen gas, and 4,4'-DAS (4,4'-diaminodiphenyl sulfone) (14.2 g) and TFMB (12. 2 g) and both terminal amine-modified methylphenyl silicone oil (10.56 g) were added with stirring, and then PMDA (15.3 g) and BPDA (8.8 g) were added as acid dianhydrides (acid dianhydride). , Diamine molar ratio (100:98)). Next, the temperature was raised to 80 ° C. using an oil bath and stirred for 4 hours, then the oil bath was removed and the temperature was returned to room temperature to obtain a transparent NMP solution of polyamic acid (hereinafter, also referred to as varnish). The obtained varnish was stored in a freezer (setting -20 ° C., the same applies hereinafter), and was thawed and used for evaluation.

<Comparative Examples 1-2-1-6>
The same procedure as in Comparative Example 1-1 was carried out except that the amount of NMP was changed to the solid content in Table 1.

<Example 1-1>
While introducing nitrogen gas into a 3 L separable flask with a stirring rod, 4,4'-DAS (15.3 g) and TFMB (12.4 g) as diamines, and twice the total mass of these diamines. A polymerization solvent (NMP) was added.
Next, a dropping funnel was set in the separable flask, and PMDA (15.3 g) and BPDA (8.8 g) as acid dianhydrides while introducing nitrogen gas into the dropping funnel, and these acid dianhydrides. Twice the mass of polymerization solvent (NMP) was added. Then, the mixture was stirred at room temperature with a small stirring blade.
Subsequently, another dropping funnel was set in the separable flask, and while introducing nitrogen gas into the dropping funnel, both terminal amine-modified methylphenyl silicone oil X-22-1660B-3 (10.56 g) and the said diamine were used. A polymerization solvent (NMP) with twice the mass of silicone oil was added. Then, the mixture was stirred at room temperature with a small stirring blade.
Then, while stirring the diamine solution in the separable flask, the small stirring blade of the dropping funnel was kept stirring at room temperature, and at the same time, dropping of the acid dianhydride solution and the silicone oil was started. The dropping was performed at a low speed, and the dropping was carried out over 30 minutes or more. After the dropping, the mixture was washed with a washing solvent (NMP), and the residue was dropped (acid dianhydride, molar ratio of diamine (100:99)).
Then, an additional solvent (NMP) was added to finally reach the solid content in Table 1. Subsequently, the mixture was stirred at room temperature for 30 minutes, then heated to 70 ° C. using an oil bath and stirred for 4 hours. Then, the oil bath was removed and the temperature was returned to room temperature to obtain a transparent NMP solution of polyamic acid (hereinafter, also referred to as varnish). The obtained varnish was stored in a freezer (setting -20 ° C., the same applies hereinafter), and was thawed and used for evaluation.

<Examples 1-2 to 1-17, 2-1 to 2-14, 3-1 to 3-16, 4-1 to 4-12>
The composition of the acid dianhydride and the diamine is as shown in Tables 1 to 4, and the amount of the polymerization solvent used is changed accordingly (that is, the amount is adjusted to be twice the mass of the acid dianhydride or the diamine). ), Further, for Examples 1-5 to 1-8, 2-5 to 2-14, 3-3 to 3-16, 4-5 to 4-12, "heat up to 70 ° C. and stir for 4 hours". Change to "heat up to 40 ° C. and stir for 12 hours", and for Examples 1-9, 2-9, 3-9, 4-9, "additional solvent (NMP)" was changed to "additional solvent (NMP and GBL)". (Adjusted so that the NMP / GBL after addition becomes 100/100 (w / w)) ”, and the same as in Example 1-1. The solid content shown in Tables 1 to 4 was adjusted to the value shown in the table by changing the amount of the additional solvent. In Examples 1-16, 2-12, 2-13, 3-14, 3-15, 4-10, 4-11, the weight average molecular weight was measured after "stirring for 12 hours" and further extending the reaction time. As a result, it did not become larger than that after stirring for 12 hours.

<Comparative Examples 2-1 to 2-6, 3-1 to 3-6, 4-1 to 4-7>
Comparative Examples 2-1, 3-1 and 4-1 have NMP amounts of Comparative Example 1-1 of 745 g (Comparative Example 2-1), 799 g (Comparative Example 3-1) and 850 g (Comparative Example 4-1). The same procedure as in Comparative Example 1-1 was carried out except that the formulations of acid dianhydride and diamine were as shown in Table 2. Further, except that the amount of NMP was changed to the solid content content in Tables 2 to 4, Comparative Examples 2-2-2-6 were compared with Comparative Example 2-1 and Comparative Examples 3-2-3-6. 3-1 and Comparative Examples 4-2-4-7 were performed in the same manner as in Comparative Example 4-1.

<Comparative Example 5-1>
NMP (620 g) was added to a 3 L separable flask with a stirring rod while introducing nitrogen gas, 4,4'-DAS (24.8 g) as a diamine was added with stirring, and then PMDA (PMDA (24.8 g) as an acid dianhydride was added. 21.8 g) was added (molar ratio of acid dianhydride and diamine (100: 100)). Next, the temperature was raised to 80 ° C. using an oil bath and stirred for 4 hours, then the oil bath was removed and the temperature was returned to room temperature to obtain a transparent NMP solution of polyamic acid (hereinafter, also referred to as varnish). The obtained varnish was stored in a freezer and thawed for evaluation.

<Comparative Examples 5-2-5-6>
The procedure was the same as in Comparative Example 5-1 except that the amount of NMP was changed to the solid content in Table 5.

<Example 5-1>
To a 3 L separable flask with a stirring rod, 4,4'-DAS (24.3 g) as a diamine and NMP having a mass twice the total mass of the diamine were added while introducing nitrogen gas.
Next, a dropping funnel was set in the separable flask, and PMDA (10.9 g), BPDA (14.7 g) and 2 of these acid dianhydrides were used as acid dianhydrides while introducing nitrogen gas into the dropping funnel. Double the mass of NMP was added. Then, the mixture was stirred at room temperature with a small stirring blade.
Then, while stirring the diamine solution in the separable flask, the dropping of the acid dianhydride solution was started at room temperature with the small stirring blades of the dropping funnel being stirred. The dropping was performed at a low speed, and the dropping was carried out over 30 minutes or more. After the dropping, the mixture was washed with a washing solvent (NMP), and the residue was dropped (acid dianhydride, molar ratio of diamine (100:98)).
Then, an additional solvent (NMP) was added to finally reach the solid content in Table 5. Subsequently, the mixture was stirred at room temperature for 30 minutes, then heated to 70 ° C. using an oil bath and stirred for 4 hours. Then, the oil bath was removed and the temperature was returned to room temperature to obtain a transparent NMP solution of polyamic acid (hereinafter, also referred to as varnish). The obtained varnish was stored in a freezer (setting -20 ° C., the same applies hereinafter), and was thawed and used for evaluation.

<Examples 5-2-5-9, 6-1-6-9, 7-1-7-4, 8-1, 8-2>
The composition of the acid dianhydride and the diamine is as shown in Tables 5 to 9, and the amount of the polymerization solvent used is changed accordingly (that is, the amount is adjusted to be twice the mass of the acid dianhydride or the diamine. ), Further, for Examples 5-3-5-9, 6-5-6-9, 7-4, 8-1, 8-2, the above-mentioned "heated to 70 ° C. and stirred for 4 hours" was changed to "40 ° C." The temperature was changed to "12 hours stirring", and for Examples 5-7, 6-4, 7-4, "additional solvent (NMP)" was changed to "additional solvent (NMP and GBL) (NMP / GBL after addition). Was changed to 100/100 (w / w)) ”, and was the same as in Example 5-1. The solid content shown in Tables 5 to 9 was adjusted to the value shown in the table by changing the amount of the additional solvent. In Examples 5-8, 5-9, 6-6 to 6-9, the reaction time was further extended after "stirring for 12 hours", but the weight average molecular weight was measured and found to be larger than that after stirring for 12 hours. There was nothing.

<Comparative Examples 6-1 to 6-6, 7-1 to 7-8, 8 to 1 to 8-2>
Comparative Examples 6-1 and 7-1 and 8-1 to 8-2 increased the amount of NMP of Comparative Example 5-1 to 664 g (Comparative Example 6-1), 718 g (Comparative Example 7-1), and 401 g (Comparative Example 7-1). 8-1) and 344 g (Comparative Example 8-2) were changed, respectively, and the same procedure as in Comparative Example 5-1 was carried out except that the formulations of acid dianhydride and diamine were as shown in Tables 6 to 8. .. Comparative Examples 6-2 to 6-6 were carried out in the same manner as in Comparative Example 6-1 except that the NMP amount was changed to the solid content content in Table 6, and Comparative Examples 7-2 to 7-6 were NMP. The same procedure as in Comparative Example 7-1 was carried out except that the amount was changed to the solid content content in Table 7. In Comparative Examples 7-7 and 7-8, the amount of NMP was changed from 718 g to 215 g (Comparative Example 7-7) and 163 g (Comparative Example 7-8), respectively, and the formulations of acid dianhydride and diamine were shown in Table 7. As shown, the same procedure as in Comparative Example 7-1 was carried out except that "4 hour stirring" was changed to "3 hour stirring".

<Comparative Example 9-1>
NMP (495 g) was added to a 3 L separable flask with a stirring rod while introducing nitrogen gas, TFMB (30.9 g) was added as a diamine while stirring, and then BPAF (9,9-bis) was added as an acid dianhydride. (3,4-Dicarboxyphenyl) fluorene dianhydride) (45.8 g) and X-22-1660B-3 (10.56 g) of both-terminal amine-modified methylphenyl silicone oil were added (acid dianhydride, Diamine molar ratio (100:99)). Next, the temperature was raised to 80 ° C. using an oil bath and stirred for 4 hours, then the oil bath was removed and the temperature was returned to room temperature to obtain a transparent NMP solution of polyamic acid (hereinafter, also referred to as varnish). The obtained varnish was stored in a freezer and thawed for evaluation.

<Comparative Examples 9-2 to 9-3>
Comparative Examples except that the amount of NMP was changed from 495 g to 438 g (Comparative Example 9-2) and 374 g (Comparative Example 9-3), respectively, and the blending of acid dianhydride and diamine was as shown in Table 9. The procedure was the same as for 9-1.

<Example 9-1>
To a 3 L separable flask with a stirring rod, TFMB (31.3 g) as a diamine and NMP (63 g) having a mass twice the total mass of the diamine were added while introducing nitrogen gas.
Next, a dropping funnel was set in the separable flask, and while introducing nitrogen gas into the dropping funnel, BPAF (45.8 g) as an acid dianhydride and NMP (92 g) having twice the mass of this acid dianhydride were used. Was added. Then, the mixture was stirred at room temperature with a small stirring blade.
Subsequently, another dropping funnel was set in the separable flask, and while introducing nitrogen gas into the dropping funnel, both terminal amine-modified methylphenyl silicone oil X-22-1660B-3 (10.56 g) and the silicone oil were added. 2 times the mass of NMP (21 g) was added. Then, the mixture was stirred at room temperature with a small stirring blade.
Then, while stirring the diamine solution in the separable flask, the dropping of the acid dianhydride solution was started at room temperature with the small stirring blades of the dropping funnel being stirred. The dropping was performed at a low speed, and the dropping was carried out over 30 minutes or more. After the dropping, the mixture was washed with a washing solvent (NMP), and the residue was dropped (acid dianhydride, molar ratio of diamine (100: 100)).
Then, an additional solvent (NMP) was added to finally reach the solid content in Table 9.
Subsequently, the mixture was stirred at room temperature for 30 minutes, then heated to 40 ° C. using an oil bath and stirred for 12 hours. Then, the oil bath was removed and the temperature was returned to room temperature to obtain a transparent NMP solution of polyamic acid (hereinafter, also referred to as varnish). The obtained varnish was stored in a freezer (setting -20 ° C., the same applies hereinafter), and was thawed and used for evaluation.

<Examples 9-2, 9-3>
The composition of the acid dianhydride and the diamine was as shown in Table 9, and the amount of the polymerization solvent used was changed accordingly (that is, the amount was adjusted to be twice the mass of the acid dianhydride or the diamine). Others were the same as in Example 9-1. The solid content shown in Table 9 was adjusted to the value shown in the table by changing the amount of the additional solvent.

<Example 10-1>
NMP (246 g) was added to a 3 L separable flask with a stirring rod while introducing nitrogen gas, and 4,4'-DAS (14.4 g), TFMB (12.4 g), and both-terminal amine-modified methylphenyl silicone were added as diamines. Oil (10.56 g) was added with stirring, followed by PMDA (15.3 g) and BPDA (8.8 g) as acid dianhydrides (acid dianhydride, molar ratio of diamine (100:99)). ). Next, the temperature was raised to 70 ° C. using an oil bath and stirred for 8 hours, and then the oil bath was removed and the temperature was returned to room temperature to obtain a transparent NMP solution of polyamic acid. The obtained varnish was stored in a freezer (setting -20 ° C., the same applies hereinafter), and was thawed and used for evaluation.

<Examples 10-2 to 10-5>
The amount of NMP was changed from 246 g to 225 g (Example 10-2), 242 g (Example 10-3), 185 g (Example 10-4), and 201 g (Example 10-5), respectively, and the acid dianhydride and The procedure was the same as in Example 10-1 except that the diamine was blended as shown in Table 10.
The evaluation results are shown in Table 10.

The resin composition of the present disclosure can be suitably applied to applications such as flexible devices (for example, flexible substrates), particularly flexible displays. For example, the resin composition of the present disclosure can be suitably used for forming a transparent substrate of a display device such as a liquid crystal display, an organic electroluminescence display, a field emission display, and electronic paper. More specifically, the resin composition of the present disclosure can be used for forming a substrate of a thin film transistor (TFT), a substrate of a color filter, a substrate of a transparent conductive film (ITO, Indium Thin Oxide), and the like.

2a Lower substrate 2b Encapsulation substrate 25 Organic EL structure 250a Organic EL element that emits red light 250b Organic EL element that emits green light 250c Organic EL element that emits blue light 251 Partition (bank)
252 Lower electrode (anode)
253 Hole transport layer 254 Light emitting layer 255 Upper electrode (cathode)
256 TFT
257 Contact hole 258 Interlayer insulating film 259 Lower electrode 261 Hollow part

Claims (25)

The following formula (1):

{In the formula, R _1, each independently represent a divalent organic group and when a plurality of, R ₂ are each independently when a plurality of a tetravalent organic group, n is a positive integer. }, A resin composition containing a polyimide precursor having a structure represented by} and a solvent.
The polyimide precursor has a weight average molecular weight of 110,000 to 250,000.
A resin composition having a solid content of 10 to 25% by mass. The claim that the shear rate dependence (TI) represented by the following formula is 0.9 to 1.1 when the viscosity of the resin composition is measured at 23 ° C. with a viscometer equipped with a temperature controller. The resin composition according to 1.
TI = ηa / ηb
{In the formula, ηa (mPa · s) is the viscosity of the resin composition at the measured rotation speed a (rpm), and ηb (mPa · s) is the viscosity of the resin composition at the measured rotation speed b (rpm). However, a * 10 = b. } The resin composition according to claim 1 or 2, wherein the resin composition is a resin composition for slit coating. At least one of R _{1 in} the above formula (1) is the following formula (2):

The resin composition according to any one of claims 1 to 3, which is a group represented by. The polyimide precursor has the following formula (3):

{In the formula, each of R ₃ and R ₄ independently indicates a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms, respectively. , And m is an integer from 1 to 200. } The resin composition according to any one of claims 1 to 4, which has a structure represented by. The resin composition according to any one of claims 1 to 5, wherein the polyimide precursor is a copolymer of a tetracarboxylic dianhydride containing a pyromellitic dianhydride and a diamine. Any one of claims 1 to 6, wherein the polyimide precursor is a copolymer of a tetracarboxylic dianhydride containing 3,3', 4,4'-biphenyltetracarboxylic dianhydride and a diamine. The resin composition according to the section. The polyimide precursor is a copolymer of tetracarboxylic dianhydride and diamine, and the tetracarboxylic dianhydride is pyromellitic dianhydride and 3,3', 4,4'-biphenyltetra. 1. The carboxylic acid dianhydride is contained in a molar ratio of the pyromellitic dianhydride to the 3,3', 4,4'-biphenyltetracarboxylic dianhydride at a molar ratio of 20:80 to 80:20. The resin composition according to any one of 7 to 7. The polyimide precursors are tetracarboxylic acid dianhydride, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,2'-bis (trifluoromethyl) benzidine and 9,9-bis. The resin composition according to any one of claims 1 to 8, which is a copolymer with one or more diamines selected from the group consisting of (4-aminophenyl) fluorene. The resin composition according to any one of claims 1 to 9, wherein the polyimide precursor has a weight average molecular weight of 160,000 to 220,000. The resin composition according to any one of claims 1 to 10, wherein the resin composition is a resin composition for a flexible device. The resin composition according to any one of claims 1 to 11, wherein the resin composition is a resin composition for a flexible display. A polyimide film which is a cured product of the resin composition according to any one of claims 1 to 12. The polyimide film according to claim 13, wherein the thickness direction retardation (Rth) in terms of film thickness of 10 μm is 300 or less, and / or the yellowness (YI) in terms of film thickness of 10 μm is 20 or less. A flexible device comprising the polyimide film according to claim 13 or 14. A flexible display comprising the polyimide film according to claim 13 or 14. The flexible display according to claim 16, wherein the polyimide film is arranged at a position that can be visually recognized when the flexible display is observed from the outside. A coating step of applying the resin composition according to any one of claims 1 to 12 onto the surface of the support.
A film forming step of heating the resin composition to form a polyimide film, and
A method for producing a polyimide film, which comprises a peeling step of peeling the polyimide film from the support. The method for producing a polyimide film according to claim 18, wherein the coating step comprises slit-coating the resin composition. At least one of R _{1 in} the above formula (1) is the following formula (2):

The method for producing a polyimide film according to claim 19, which is a group represented by. The polyimide precursor has the following formula (3):

{In the formula, each of R ₃ and R ₄ independently indicates a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms, respectively. , And m is an integer from 1 to 200. } The method for producing a polyimide film according to claim 19 or 20, which has a structure represented by. The method for producing a polyimide film according to any one of claims 18 to 21, further comprising an irradiation step of irradiating the polyimide film with a laser from the support side prior to the peeling step. A coating step of applying the resin composition according to any one of claims 1 to 12 onto the surface of the support.
A film forming step of heating the resin composition to form a polyimide film, and
The element forming step of forming an element on the polyimide film and
A method for manufacturing a display, comprising a peeling step of peeling the polyimide film on which the element is formed from the support. The method for manufacturing a display according to claim 23, wherein the coating step includes slit coating the resin composition. The method for manufacturing a display according to claim 23 or 24, wherein the polyimide film is arranged at a position that is visible when the display is observed from the outside.

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