JP7011230B2 - Composition for forming a flexible device substrate - Google Patents

Description

The present invention relates to a composition for forming a flexible device substrate, and more specifically, it can be suitably used for forming a flexible device substrate such as a flexible display using a laser lift-off method in a step of peeling the substrate from a carrier substrate. Regarding the composition.

In recent years, with the rapid progress of electronics such as liquid crystal displays and organic electroluminescence displays, there has been a demand for devices to be thinner, lighter, and more flexible.
In these devices, various electronic elements such as thin film transistors and transparent electrodes are formed on a glass substrate. By replacing this glass material with a flexible and lightweight resin material, the device itself can be made thinner and lighter. It can be made more flexible.
Under these circumstances, polyimide is attracting attention as an alternative material to glass. In addition, the polyimide for this application is required to have not only flexibility but also transparency similar to that of glass in most cases. In order to realize these characteristics, semi-alicyclic polyimides and total alicyclic polyimides obtained by using an alicyclic diamine component or an alicyclic anhydrous component as a raw material have been reported (for example, Patent Documents 1 to 1). 3).

On the other hand, in the manufacture of flexible displays, it has been reported that the polymer substrate can be suitably peeled from the glass carrier by using the laser lift-off method (LLO method) which has been used in the manufacture of high-brightness LEDs and three-dimensional semiconductor packages. (For example, Non-Patent Document 1).
In the manufacture of flexible displays, a polymer substrate made of polyimide or the like is provided on a glass carrier, then a circuit or the like including electrodes or the like is formed on the substrate, and finally the substrate is peeled off from the glass carrier together with this circuit or the like. There is a need. In this peeling step, the LLO method is adopted, that is, when the glass carrier is irradiated with a light ray having a specific wavelength from the surface opposite to the surface on which the circuit or the like is formed, the light ray having the specific wavelength passes through the glass carrier and the glass carrier. Only the nearby polymer (polyimide) absorbs this light beam and evaporates (sublimates). As a result, it has been reported that the substrate can be selectively peeled off from the glass carrier without affecting the circuit or the like provided on the substrate, which determines the performance of the display.

Japanese Unexamined Patent Publication No. 2013-147599 Japanese Unexamined Patent Publication No. 2014-114429 International Publication No. 2015/152178

Journal of Information Display, 2014, Vol 15, No.1, p.p.1-4

Due to the above-mentioned process advantages, the LLO method is more likely to be adopted as an extremely superior substrate peeling method in the manufacture of flexible displays. As the practical use of flexible displays and the increasing reality of mass production, the demand for polymer substrates for flexible displays to which the LLO method can be applied will also increase.
The semi-alicyclic polyimides and full-alicyclic polyimides that have been proposed so far as promising substrate materials for flexible displays have excellent heat resistance, low retardation, excellent flexibility, and excellent transparency. However, there is a problem that it is difficult for the substrate to be peeled off from the glass carrier by the LLO method.

The present invention has been made in view of such circumstances, and maintains excellent performance of excellent heat resistance, low retardation, excellent flexibility, and excellent transparency, and by the LLO method. It is an object of the present invention to provide a composition for forming a flexible device substrate, which provides a resin thin film having excellent performance as a base film of a flexible device substrate such as a flexible display substrate that can be easily peeled off from a glass carrier.

As a result of diligent studies to achieve the above object, the present inventors have selected a tetracarboxylic acid dianhydride component containing an alicyclic tetracarboxylic acid dianhydride and a diamine component containing a fluorine-containing aromatic diamine. When an aromatic tetracarboxylic acid dianhydride having a specific structure is contained as a tetracarboxylic acid dianhydride component when producing a polyimide, the polyimide obtained thereby has heat resistance when formed into a resin thin film. The present invention has been completed by finding that it can exhibit excellent performances such as excellent in swelling, low polyimide, excellent flexibility, and excellent transparency, and can be easily peeled off from a glass carrier by the LLO method.

（式中、Ｅは、単結合、カルボニル基、酸素原子、硫黄原子、ＳＯ又はＳＯ₂を表す。）
第２観点として、前記脂環式テトラカルボン酸二無水物が、式（Ｃ１）で表される脂環式テトラカルボン酸二無水物を含む、第１観点に記載のフレキシブルデバイス基板形成用組成物に関する。

〔式中、Ｂ¹は、式（Ｘ－１）～（Ｘ－１２）からなる群から選ばれる４価の基を表す。

（式中、複数のＲは、互いに独立して、水素原子またはメチル基を表し、＊は結合手を表す。）〕
第３観点として、前記含フッ素芳香族ジアミンが、式（Ａ１）で表されるジアミンを含む、第１観点または第２観点に記載のフレキシブルデバイス基板形成用組成物に関する。

（式中、Ｂ²は、式（Ｙ－１）～（Ｙ－３４）からなる群から選ばれる２価の基を表す。）

（式中、＊は結合手を表す。）
第４観点として、前記テトラカルボン酸二無水物成分は、式（Ｄ１）で表される芳香族テトラカルボン酸二無水物を、テトラカルボン酸二無水物成分の全モル数に対して、１モル％ないし３０モル％含む、第１観点乃至第３観点のうちいずれか一つに記載のフレキシブルデバイス基板形成用組成物に関する。
第５観点として、更に、窒素吸着法により測定された比表面積値から算出される平均粒子径が１００ｎｍ以下である二酸化ケイ素粒子を含む、第１観点乃至第４観点のうちいずれか一つに記載のフレキシブルデバイス基板形成用組成物に関する。
第６観点として、前記ポリイミドと前記二酸化ケイ素粒子の質量比が、７：３～３：７である、第５観点に記載のフレキシブルデバイス基板形成用組成物に関する。
第７観点として、前記平均粒子径が、６０ｎｍ以下である、第５観点または第６観点に記載のフレキシブルデバイス基板形成用組成物に関する。
第８観点として、レーザーリフトオフ法に用いるためのフレキシブルデバイスの基板形成用組成物である、第１観点乃至第７観点のうちいずれか一つに記載のフレキシブルデバイス基板形成用組成物に関する。
第９観点として、第１観点乃至第７観点のうちいずれか一つに記載のフレキシブルデバイス基板形成用組成物を用いて作成されたフレキシブルデバイス基板に関する。
第１０観点として、第１観点乃至第７観点のうちいずれか一つに記載のフレキシブルデバイス基板形成用組成物を基材に塗布し、乾燥・加熱してフレキシブルデバイス基板を形成する工程、
レーザーリフトオフ法により前記基材から前記フレキシブルデバイス基板を剥離させる剥離工程を含む、フレキシブルデバイス基板の製造方法に関する。That is, the present invention has, as a first aspect, a tetracarboxylic acid dianhydride component containing an alicyclic tetracarboxylic acid dianhydride and an aromatic tetracarboxylic acid dianhydride represented by the formula (D1), and a fluorine-containing fragrance. The present invention relates to a composition for forming a flexible device substrate, which comprises a polyimide which is a reaction product with a diamine component containing a group diamine and an organic solvent.

(In the formula, E represents a single bond, a carbonyl group, an oxygen atom, a sulfur atom, SO or SO _2. )
As a second aspect, the composition for forming a flexible device substrate according to the first aspect, wherein the alicyclic tetracarboxylic dianhydride contains an alicyclic tetracarboxylic dianhydride represented by the formula (C1). Regarding.

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-1) to (X-12).

(In the equation, multiple Rs represent hydrogen atoms or methyl groups independently of each other, and * represents a bond.)]
As a third aspect, the composition for forming a flexible device substrate according to the first aspect or the second aspect, wherein the fluorine-containing aromatic diamine contains a diamine represented by the formula (A1).

(In the formula, B ² represents a divalent group selected from the group consisting of formulas (Y-1) to (Y-34).)

(In the formula, * represents a bond.)
As a fourth aspect, the tetracarboxylic acid dianhydride component is an aromatic tetracarboxylic acid dianhydride represented by the formula (D1) in an amount of 1 mol based on the total number of moles of the tetracarboxylic acid dianhydride component. The composition for forming a flexible device substrate according to any one of the first aspect to the third aspect, which comprises% to 30 mol%.
As a fifth aspect, further described in any one of the first aspect to the fourth aspect, which includes silicon dioxide particles having an average particle size of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method. The present invention relates to a composition for forming a flexible device substrate.
As a sixth aspect, the composition for forming a flexible device substrate according to the fifth aspect, wherein the mass ratio of the polyimide and the silicon dioxide particles is 7: 3 to 3: 7.
As a seventh aspect, the composition for forming a flexible device substrate according to the fifth or sixth aspect, wherein the average particle size is 60 nm or less.
As an eighth aspect, the present invention relates to the flexible device substrate forming composition according to any one of the first aspect to the seventh aspect, which is a substrate forming composition for a flexible device for use in the laser lift-off method.
As a ninth aspect, the present invention relates to a flexible device substrate prepared by using the composition for forming a flexible device substrate according to any one of the first aspect to the seventh aspect.
As a tenth aspect, a step of applying the composition for forming a flexible device substrate according to any one of the first to seventh aspects to a substrate, drying and heating to form a flexible device substrate.
The present invention relates to a method for manufacturing a flexible device substrate, which comprises a peeling step of peeling the flexible device substrate from the substrate by a laser lift-off method.

According to the present invention, the excellent performance of excellent heat resistance, low retardation, excellent flexibility, and excellent transparency (high light transmittance, low yellowness) is maintained, and the LLO method makes it easy to remove from a glass carrier. It is possible to provide a composition for forming a flexible device substrate that provides a resin thin film having excellent performance as a base film for a flexible device substrate such as a flexible display substrate that can be peeled off.
The flexible device substrate according to the present invention maintains excellent performance of excellent heat resistance, low retardation, excellent flexibility, and excellent transparency (high light transmittance, low yellowness), and at the same time. Since it can be easily peeled off from the glass carrier by the LLO method, it can be suitably used as a substrate for a flexible device, particularly a flexible display.
Further, according to the method for manufacturing a flexible device substrate according to the present invention, excellent performance such as excellent heat resistance, low retardation, excellent flexibility, and excellent transparency (high light transmittance, low yellowness) is achieved. Since the flexible device substrate can be easily manufactured by peeling it from the glass carrier by the LLO method, it can be a manufacturing method excellent in productivity and economy.
Such a composition, a substrate and a manufacturing method according to the present invention have characteristics such as high heat resistance, low retardation, high flexibility, high transparency (high light transmittance, low yellowness) and peelability by the LLO method. It is possible to sufficiently cope with the progress in the field of the required flexible device substrate, particularly the flexible display substrate.

（式中、Ｅは、単結合、カルボニル基、酸素原子、硫黄原子、ＳＯ又はＳＯ₂を表す。）Hereinafter, the present invention will be described in detail.
The composition for forming a flexible device substrate of the present invention comprises a tetracarboxylic acid dianhydride component containing a specific alicyclic tetracarboxylic acid dianhydride and an aromatic tetracarboxylic acid dianhydride represented by the formula (D1). Contains a polyimide and an organic solvent, which is an imidized polyamic acid that is a reaction product with a diamine component containing a specific fluorine-containing aromatic diamine, and optionally contains silicon dioxide particles, a cross-linking agent, and other components.

(In the formula, E represents a single bond, a carbonyl group, an oxygen atom, a sulfur atom, SO or SO _2. )

[Polyimide]
The polyimide used in the present invention is a polyimide having an alicyclic skeleton in the main chain, preferably an alicyclic tetracarboxylic acid dianhydride and an aromatic tetracarboxylic acid dianhydride represented by the above formula (D1). It is a polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic acid dianhydride component containing an anhydride with a diamine component containing a fluorine-containing aromatic diamine. That is, the polyimide is preferably an imidized polyamic acid, and the polyamic acid is an alicyclic tetracarboxylic acid dianhydride and an aromatic tetracarboxylic acid dianhydride represented by the formula (D1). It is a reaction product of a tetracarboxylic acid dianhydride component containing and a diamine component containing a fluorine-containing aromatic diamine.
Among them, the alicyclic tetracarboxylic dianhydride contains an alicyclic tetracarboxylic dianhydride represented by the following formula (C1), and the fluoroaromatic diamine contains the following formula (A1). ) Is preferably contained.

〔式中、Ｂ¹は、式（Ｘ－１）～（Ｘ－１２）からなる群から選ばれる４価の基を表す。

（式中、複数のＲは、互いに独立して、水素原子またはメチル基を表し、＊は結合手を表す。）〕

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-1) to (X-12).

(In the equation, multiple Rs represent hydrogen atoms or methyl groups independently of each other, and * represents a bond.)]

（式中、Ｂ²は、式（Ｙ－１）～（Ｙ－３４）からなる群から選ばれる２価の基を表す。）

（式中、＊は結合手を表す。）

(In the formula, B ² represents a divalent group selected from the group consisting of formulas (Y-1) to (Y-34).)

(In the formula, * represents a bond.)

式（Ｄ１）で表される芳香族テトラカルボン酸二無水物の中でも、式（Ｚ－１）、（Ｚ－２）で表される化合物であることが好ましい。
好適な例として、上記式（Ｃ１）で表される脂環式テトラカルボン酸二無水物及び上記式（Ｄ１）で表される芳香族テトラカルボン酸二無水物と、上記式（Ａ１）で表されるジアミンとを反応させて得られるポリアミック酸をイミド化して得られるポリイミドは、後述する式（２）で表されるモノマー単位を含む。Among the alicyclic tetracarboxylic dianhydrides represented by the above formula (C1), B ¹ in the formula is the formulas (X-1), (X-4), (X-6), (X-7). ) Is preferable.
Further, among the diamines represented by the above (A1), it is preferable that B ² in the formula is a compound represented by the formulas (Y-12) and (Y-13).
The aromatic tetracarboxylic dianhydride represented by the formula (D1) is a compound represented by a formula selected from the group consisting of the formulas (Z-1) to (Z-6) shown below. Can be mentioned.

Among the aromatic tetracarboxylic dianhydrides represented by the formula (D1), the compounds represented by the formulas (Z-1) and (Z-2) are preferable.
As suitable examples, the alicyclic tetracarboxylic acid dianhydride represented by the above formula (C1), the aromatic tetracarboxylic acid dianhydride represented by the above formula (D1), and the above formula (A1) are represented. The polyimide obtained by imidizing the polyamic acid obtained by reacting with the diamine to be obtained contains a monomer unit represented by the formula (2) described later.

A flexible device substrate that can be easily peeled off from a glass carrier by the LLO method while maintaining excellent performance such as excellent heat resistance, low retardation, excellent flexibility, and excellent transparency, which is the object of the present invention. In order to obtain the alicyclic tetracarboxylic acid dianhydride, for example, the alicyclic tetracarboxylic acid dianhydride represented by the above formula (C1), is used with respect to the total number of moles of the tetracarboxylic acid dianhydride component. It is preferably 70 mol% or more, more preferably 80 mol% or more, and the aromatic tetracarboxylic represented by the formula (D1) with respect to the total number of moles of the tetracarboxylic acid dianhydride component. The acid dianhydride is preferably 1 mol% or more and 30 mol% or less, and more preferably 5 mol% or more and 20 mol% or less.
Similarly, in order to maintain excellent performance of excellent heat resistance, low retardation, excellent flexibility, and excellent transparency, and to obtain a flexible device substrate that can be easily peeled off from the glass carrier by the LLO method. The amount of the fluorine-containing aromatic diamine, for example, the diamine represented by the formula (A1) is preferably 90 mol% or more, more preferably 95 mol% or more, based on the total number of moles of the diamine component. .. Further, all of the diamine components (100 mol%) may be diamine represented by the above formula (A1).

As an example of a preferred embodiment, the polyimide used in the present invention contains a monomer unit represented by the following formula (1) and a monomer unit represented by the following formula (1').
In the following formula, E ₁ means a single bond or a carbonyl group.

As the monomer unit represented by the above formula (1), those represented by the formula (1-1) or the formula (1-2) are preferable, and those represented by the formula (1-1) are more preferable.

The monomer unit represented by the above formula (1') is preferably represented by the formula (1'-1) or the formula (1'-2), and is represented by the formula (1'-1). Is more preferable.

According to a preferred embodiment of the present invention, the polyimide used in the present invention is represented by the formula (2) in addition to the monomer unit represented by the formula (1) and the monomer unit represented by the formula (1'). Further contains the monomer unit to be added.

As the monomer unit represented by the above formula (2), those represented by the formula (2-1) or the formula (2-2) are preferable, and those represented by the formula (2-1) are more preferable.

When the polyimide used in the present invention contains a monomer unit represented by the above formula (1), a monomer unit represented by the formula (1') and a monomer unit represented by the formula (2), the polyimide chain contains. In terms of molar ratio, it is preferable to include the monomer unit represented by the formula (1): the monomer unit represented by the formula (2) = 10: 1 to 1:10, and more preferably 7: 3 to 3: 10. It is preferably contained in a ratio of 7, and the monomer unit represented by the formula (1) + the monomer unit represented by the formula (2): the monomer unit represented by the formula (1') = 7: 3 to 19: 1. It is preferable to include it in a ratio of 8: 2 to 19: 1, and more preferably it is contained in a ratio of 8: 2 to 19: 1.

The polyimide of the present invention is a tetracarboxylic acid dianhydride containing an alicyclic tetracarboxylic acid dianhydride represented by the above formula (C1) and an aromatic tetracarboxylic acid dianhydride represented by the formula (D1). In addition to the monomer units derived from the component and the diamine component containing the diamine represented by the formula (A1), for example, the monomer units represented by the above formulas (1), (1') and (2). , Other monomer units may be included. The content ratio of the other monomer units is arbitrarily determined as long as the characteristics of the flexible device substrate formed from the composition for forming the flexible device substrate of the present invention are not impaired. The ratio is the same as that of the tetracarboxylic acid dianhydride component containing the alicyclic tetracarboxylic acid dianhydride represented by the above formula (C1) and the aromatic tetracarboxylic acid dianhydride represented by the formula (D1). , The total number of moles of the monomer unit derived from the diamine component containing the diamine represented by the formula (A1), for example, the monomer unit represented by the formula (1) and the monomer unit represented by the formula (1'). On the other hand, or when the monomer unit represented by the formula (2) is included, the monomer unit represented by the formula (1), the monomer unit represented by the formula (1') and the monomer unit represented by the formula (2). With respect to the total number of moles of the represented monomer units, less than 20 mol% is preferable, less than 10 mol% is more preferable, and less than 5 mol% is even more preferable.

Examples of such other monomer units include, but are not limited to, monomer units having another polyimide structure represented by the formula (3).

In the formula (3), A represents a tetravalent organic group, preferably a tetravalent group represented by any of the following formulas (A-1) to (A-4). Further, in the above formula (3), B represents a divalent organic group, preferably a divalent group represented by any of the formulas (B-1) to (B-11). In each equation, * represents a bond. In the formula (3), when A represents a tetravalent group represented by any of the following formulas (A-1) to (A-4), B is the above-mentioned formulas (Y-1) to (A-4). It may be a divalent group represented by any of Y-34). Alternatively, in the formula (3), when B represents a divalent group represented by any of the following formulas (B-1) to (B-11), A represents the above-mentioned formulas (X-1) to (X). It may be a tetravalent group represented by any of -12).
When the polyimide of the present invention contains the monomer unit represented by the formula (3), A and B may contain, for example, only the monomer unit composed of only one of the groups exemplified by the following formula. However, at least one of A and B may contain two or more monomer units selected from the two or more groups exemplified below.

In the polyimide used in the present invention, each monomer unit is bonded in an arbitrary order.

As a suitable example, the polyimide having the monomer unit represented by the above formula (1) and the monomer unit represented by the formula (1') is a bicyclo [2,2] as an alicyclic tetracarboxylic acid dianhydride. , 2] Octane-2,3,5,6-tetracarboxylic acid dianhydride and 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride as aromatic tetracarboxylic acid dianhydride, or A tetracarboxylic acid dianhydride component containing 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride and a diamine component containing a diamine represented by the following formula (4) are polymerized in an organic solvent. , Can be obtained by imidizing the resulting polyamic acid.
When the polyimide used in the present invention has a monomer unit represented by the above formula (1) and a monomer unit represented by the above formula (2) in addition to the monomer unit represented by the above formula (1'). The polyimide containing the monomer units represented by the formula (1), the formula (1') and the formula (2) is a bicyclo [2,2,2] octane-2, as an alicyclic tetracarboxylic dianhydride. 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride as 3,5,6-tetracarboxylic acid dianhydride and aromatic tetracarboxylic acid dianhydride, or 3,3', 4, In addition to 4'-benzophenone tetracarboxylic acid dianhydride, a tetracarboxylic acid dianhydride component containing 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and a diamine represented by the following formula (4) are used. It can be obtained by polymerizing the contained diamine component in an organic solvent and imidizing the obtained polyamic acid.

Examples of the diamine represented by the above formula (4) include 2,2'-bis (trifluoromethyl) benzidine, 3,3'-bis (trifluoromethyl) benzidine, and 2,3'-bis (trifluoromethyl). Benzidine is mentioned.
Among them, as the fluorine-containing aromatic diamine contained in the diamine component, the flexible device substrate of the present invention has excellent heat resistance, low retardation, excellent flexibility, and excellent transparency (high light transmittance, high light transmittance, From the viewpoint of maintaining the excellent performance of (low yellowness) and making it easy to peel off from the glass carrier by the LLO method, the 2,2'-bis (trifluoro) represented by the following formula (4-1) It is preferable to use methyl) benzidine or 3,3'-bis (trifluoromethyl) benzidine represented by the following formula (4-2), and in particular, 2,2'-bis (trifluoromethyl) benzidine may be used. preferable.

Further, the polyimide used in the present invention is a tetracarboxylic acid containing an alicyclic tetracarboxylic acid dianhydride represented by the above formula (C1) and an aromatic tetracarboxylic acid dianhydride represented by the formula (D1). (2) Monomer unit derived from the anhydride component and the diamine component containing diamine represented by the formula (A1), for example, the monomer unit represented by the above formula (1) and the monomer unit represented by the formula (1'). And when it has other monomer units represented by the above formula (3) in addition to the monomer unit represented by the formula (2), the formula (1), the formula (1'), the formula (2) and the formula (3). ), In addition to the above-mentioned three types of tetracarboxylic acid dianhydride as a tetracarboxylic acid dianhydride component, the polyimide containing each monomer unit is represented by the following formula (5). It is obtained by polymerizing a product and a diamine represented by the above formula (4) as a diamine component and a diamine represented by the following formula (6) in an organic solvent to imidize the obtained polyamic acid. ..

A in the above formula (5) and B in the formula (6) have the same meanings as A and B in the above formula (3), respectively.

Specifically, the tetracarboxylic acid dianhydride represented by the formula (5) includes pyromellitic acid dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride, 11,11-. Bis (trifluoromethyl) -1H-difluoro [3,4-b: 3', 4'-i] Xanthene-1,3,7,9- (11H-tetraone), 6,6'-bis (trifluoro) Methyl)-[5,5'-biisobenzofuran]-1,1', 3,3'-tetraone, 4,6,10,12-tetrafluorodiflo [3,4-b: 3', 4' -I] Dibenzo [b, e] [1,4] Dioxin-1,3,7,9-Tetraone, 4,8-bis (trifluoromethoxy) benzo [1,2-c: 4,5-c' ] Difran-1,3,5,7-tetraone, N, N'-[2,2'-bis (trifluoromethyl) biphenyl-4,4'-diyl] bis (1,3-dioxo-1,3) -Aromatic tetracarboxylic acid dianhydrides such as (dihydroisobenzofuran-5-carbamide); 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydrides, 1,2,3,4- Tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, 1,2,3,4-cyclohexanetetracarboxylic acid dianhydride Alicyclic tetracarboxylic acid dianhydride such as 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic hydride; 1,2,3,4-butanetetrahydride. Examples include, but are not limited to, aliphatic tetracarboxylic acid dianhydrides such as acid dianhydride.
Among these, tetracarboxylic acid dianhydride in which A in the formula (5) is a tetravalent group represented by any of the above formulas (A-1) to (A-4) is preferable, that is, 11 , 11-bis (trifluoromethyl) -1H-difluoro [3,4-b: 3', 4'-i] xanthene-1,3,7,9- (11H-tetraone), 6,6'-bis (Trifluoromethyl)-[5,5'-biisobenzofuran] -1,1', 3,3'-tetraone, 4,6,10,12-tetrafluorodifluoro [3,4-b: 3' , 4'-i] Dibenzo [b, e] [1,4] Dioxin-1,3,7,9-Tetraone, 4,8-bis (trifluoromethoxy) benzo [1,2-c: 4,5 -C'] Difran-1,3,5,7-tetraone can be mentioned as a preferred compound.

Examples of the diamine represented by the formula (6) include 2- (trifluoromethyl) benzene-1,4-diamine, 5- (trifluoromethyl) benzene-1,3-diamine, and 5- (trifluoromethyl). ) Benzine-1,2-diamine, 2,5-bis (trifluoromethyl) -benzene-1,4-diamine, 2,3-bis (trifluoromethyl) -benzene-1,4-diamine, 2,6 -Bis (trifluoromethyl) -benzene-1,4-diamine, 3,5-bis (trifluoromethyl) -benzene-1,2-diamine, tetrakis (trifluoromethyl) -1,4-phenylenediamine, 2 -(Trifluoromethyl) -1,3-phenylenediamine, 4- (trifluoromethyl) -1,3-phenylenediamine, 2-methoxy-1,4-phenylenediamine, 2,5-dimethoxy-1,4- Phenylene diamine, 2-hydroxy-1,4-phenylenediamine, 2,5-dihydroxy-1,4-phenylenediamine, 2-fluorobenzene-1,4-diamine, 2,5-difluorobenzene-1,4-diamine , 2-Chlorobenzene-1,4-diamine, 2,5-dichlorobenzene-1,4-diamine, 2,3,5,6-tetrafluorobenzene-1,4-diamine, 4,4'-(perfluoro) Propane-2,2-diyl) dianiline, 4,4'-oxybis [3- (trifluoromethyl) aniline], 1,4-bis (4-aminophenoxy) benzene, 1,3'-bis (4-amino) Phenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, benzidine, 2-methylbenzidine, 3-methylbenzidine, 2- (trifluoromethyl) benzidine, 3- (trifluoromethyl) benzidine, 2,2 '-Diamine benzidine (m-tridin), 3,3'-dimethylbenzidine (o-tridin), 2,3'-dimethylbenzidine, 2,2'-dimethoxybenzidine, 3,3'-dimethoxybenzidine, 2,3 '-Dimethoxybenzidine, 2,2'-dihydroxybenzidine, 3,3'-dihydroxybenzidine, 2,3'-dihydroxybenzidine, 2,2'-difluorobenzidine, 3,3'-difluorobenzidine, 2,3'- Difluorobenzidine, 2,2'-dichlorobenzidine, 3,3'-dichlorobenzidine, 2,3'-dichlorobenzidine, 4,4'-diaminobenzanilide, 4-aminophenyl -4'-aminobenzoate, octafluorobenzidine, 2,2', 5,5'-tetramethylbenzidine, 3,3', 5,5'-tetramethylbenzidine, 2,2', 5,5'-tetrakis (Trifluoromethyl) benzidine, 3,3', 5,5'-tetrakis (trifluoromethyl) benzidine, 2,2', 5,5'-tetrachlorobenzidine, 4,4'-bis (4-aminophenoxy) ) Biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-{[3,3 "-bis (trifluoromethyl)-(1,1': 3', 1" -terphenyl ) -4,4 "-diyl] -bis (oxy)} dianiline, 4,4'-{[(perfluoropropane-2,2-diyl) bis (4,1-phenylene)] bis (oxy)} dianiline , 1- (4-Aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-inden-5 (or 6) amine and other aromatic diamines; 4,4'-methylenebis (cyclohexylamine) , 4,4'-Methylenebis (3-methylcyclohexylamine), isophoronediamine, trans-1,4-cyclohexanediamine, cis-1,4-cyclohexanediamine, 1,4-cyclohexanebis (methylamine), 2,5 -Bis (aminomethyl) bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 3,8-bis (aminomethyl) tricyclo [5.2. 1.0] Decane, 1,3-diaminoadamantan, 2,2-bis (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane, 1,3-propanediamine, 1, Alibo diamines such as 4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine. However, it is not limited to these.
Among these, aromatic diamines in which B in the formula (6) is a divalent group represented by any of the above formulas (B-1) to (B-11) are preferable, that is, 2,2'. -Bis (trifloolomethoxy)-(1,1'-biphenyl) -4,4'-diamine [also known as 2,2'-dimethoxybenzene], 4,4'-(perfluoropropane-2,2-) Diyl) dianiline, 2,5-bis (trifluoromethyl) benzene-1,4-diamine, 2- (trifluoromethyl) benzene-1,4-diamine, 2-fluorobenzene-1,4-diamine, 4, 4'-oxybis [3- (trifluoromethyl) aniline], 2,2', 3,3', 5,5', 6,6'-octafluoro [1,1'-biphenyl] -4,4' -Diamine [also known as octafluorobenzidine], 2,3,5,6-tetrafluorobenzene-1,4-diamine, 4,4'-{[3,3 "-bis (trifluoromethyl)-(1, 1': 3', 1 "-terphenyl) -4,4" -diyl] -bis (oxy)} dianiline, 4,4'-{[(perfluoropropane-2,2-diyl) bis (4, 1-Phenylene)] bis (oxy)} dianiline, 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-inden-5 (or 6) amine is mentioned as a preferred diamine. be able to.

<Synthesis of polyamic acid>
As described above, the polyimide used in the present invention contains an alicyclic tetracarboxylic acid dianhydride represented by the above formula (C1) and an aromatic tetracarboxylic acid dianhydride represented by the formula (D1). It is obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic acid dianhydride component with a diamine component containing a fluorine-containing aromatic diamine.
Specifically, for example, as a suitable example, bicyclo [2,2,2] octane-2,3,5,6-tetracarboxylic acid dianhydride and 3,3', 4,4'-biphenyltetracarboxylic acid. Dianhydride, or bicyclo [2,2,2] octane-2,3,5,6-tetracarboxylic acid dianhydride and 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, and In some cases, further 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, and if desired, a tetracarboxylic acid dianhydride component composed of a tetracarboxylic acid dianhydride represented by the above formula (5), and the above formula. It is obtained by polymerizing the diamine represented by (4) and, if desired, the diamine component composed of the diamine represented by the above formula (6) in an organic solvent to imidize the obtained polyamic acid.
The reaction of the above two components to the polyamic acid is advantageous in that it can proceed relatively easily in an organic solvent and no by-products are produced.

The charging ratio (molar ratio) of the diamine component in the reaction between the tetracarboxylic dianhydride component and the diamine component is appropriately set in consideration of the molecular weight of the polyamic acid and the polyimide obtained by subsequent imidization. However, it can be usually about 0.8 to 1.2 of the tetracarboxylic acid dianhydride component with respect to the diamine component 1, for example, about 0.9 to 1.1, preferably about 0. It is about 95 to 1.02. Similar to a normal polycondensation reaction, the closer the molar ratio is to 1.0, the larger the molecular weight of the polyamic acid produced.

The organic solvent used in the reaction between the tetracarboxylic dianhydride component and the diamine component is not particularly limited as long as it does not adversely affect the reaction and the produced polyamic acid is dissolved. Specific examples are given below.
For example, m-cresol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, 3- Methoxy-N, N-dimethylpropylamide, 3-ethoxy-N, N-dimethylpropylamide, 3-propoxy-N, N-dimethylpropylamide, 3-isopropoxy-N, N-dimethylpropylamide, 3-butoxy -N, N-dimethylpropylamide, 3-sec-butoxy-N, N-dimethylpropylamide, 3-tert-butoxy-N, N-dimethylpropylamide, γ-butyrolactone, N-methylcaprolactam, dimethylsulfoxide, tetra Methylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, isopropyl alcohol, methoxymethylpentanol, dipentene, ethylamyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cell solve, ethyl cell solve, methyl cellosolve Acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert -Butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene Glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl Acetate, butyl butyrate, butyl ether, diisobutylketone, methylcyclohexene, propyl ether, dihexy Luether, dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl acetate Ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate , Butyl 3-methoxypropionate, diglyme, 4-hydroxy-4-methyl-2-pentanone and the like, but are not limited thereto. These may be used alone or in combination of two or more.
Further, even if the solvent does not dissolve the polyamic acid, it may be mixed with the above solvent and used as long as the produced polyamic acid does not precipitate. Further, since the water content in the organic solvent inhibits the polymerization reaction and further causes the produced polyamic acid to be hydrolyzed, it is preferable to use the organic solvent dehydrated and dried as much as possible.

As a method for reacting the tetracarboxylic acid dianhydride component with the diamine component in an organic solvent, a dispersion or solution in which the diamine component is dispersed or dissolved in an organic solvent is stirred, and the tetracarboxylic acid dianhydride component is here. A method of adding a component as it is, or adding a component obtained by dispersing or dissolving the component in an organic solvent, or conversely, a diamine component in a dispersion or solution in which a tetracarboxylic acid dianhydride component is dispersed or dissolved in an organic solvent. , A method of alternately adding a tetracarboxylic acid dianhydride component and a diamine compound component, and the like, and any of these methods may be used.
When the tetracarboxylic dianhydride component and / or the diamine component are composed of a plurality of types of compounds, they may be reacted in a premixed state, may be reacted individually in sequence, or may be reacted individually. A low molecular weight compound may be mixed and reacted to obtain a high molecular weight compound.

The temperature at the time of synthesizing the polyamic acid may be appropriately set within the range from the melting point to the boiling point of the solvent used described above, and for example, any temperature of -20 ° C to 150 ° C can be selected, but -5. The temperature is preferably about 0 to 100 ° C, usually about 0 to 100 ° C, preferably about 0 to 70 ° C.
The reaction time cannot be unconditionally defined because it depends on the reaction temperature and the reactivity of the raw material, but it is usually about 1 to 100 hours.
The reaction can be carried out at any concentration, but if the concentration is too low, it becomes difficult to obtain a polymer having a high molecular weight, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring is difficult. Therefore, the total concentration of the tetracarboxylic acid dianhydride component and the diamine component in the reaction solution is preferably 1 to 50% by mass, more preferably 5 to 40% by mass. It is also possible to carry out the initial reaction at a high concentration and then add an organic solvent.

<Imidization of polyamic acid>
Examples of the method for imidizing a polyamic acid include thermal imidization in which a solution of the polyamic acid is heated as it is, and catalytic imidization in which a catalyst is added to the solution of the polyamic acid.
The temperature at which the polyamic acid is thermally imidized in the solution is 100 ° C. to 400 ° C., preferably 120 ° C. to 250 ° C., and it is preferable to remove the water generated by the imidization reaction from the system.

For chemical (catalytic) imidization of polyamic acid, a basic catalyst and acid anhydride are added to a solution of polyamic acid, and the inside of the system is subjected to a temperature condition of -20 to 250 ° C, preferably 0 to 180 ° C. It can be done by stirring.
The amount of the basic catalyst is 0.5 to 30 mol times, preferably 1.5 to 20 mol times, the amid acid group of the polyamic acid, and the amount of the acid anhydride is 1 to 50 mol times the amid acid group of the polyamic acid. It is double, preferably 2 to 30 mol times.

Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, 1-ethylpiperidine and the like, and among them, pyridine is preferable because it has an appropriate basicity for advancing the reaction.
Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like, and among them, acetic anhydride is preferable because it facilitates purification after the reaction is completed.
The imidization rate by catalytic imidization can be controlled by adjusting the amount of catalyst, the reaction temperature, and the reaction time.

In the polyimide resin used in the present invention, the dehydrated ring closure rate (imidization rate) of the amic acid group does not necessarily have to be 100%, and can be arbitrarily adjusted and used according to the intended use and purpose. Particularly preferably, it is 50% or more.

In the present invention, the reaction solution may be filtered and then the filtrate may be used as it is, or diluted or concentrated to obtain a composition for forming a flexible device substrate, which may be mixed with silicon dioxide or the like, which will be described later. It may be used as a composition for forming a flexible device substrate. When filtered in this way, not only can the contamination of impurities that can cause deterioration of the heat resistance, flexibility, or linear expansion coefficient characteristics of the obtained resin thin film be reduced, but also a composition for forming a flexible device substrate can be efficiently obtained. Can be done.

Further, the polyimide used in the present invention has a weight average molecular weight (Mw) obtained by gel permeation chromatography (GPC) in terms of polystyrene in consideration of the strength of the resin thin film, workability when forming the resin thin film, uniformity of the resin thin film, and the like. ) Is preferably 5,000 to 200,000.

<Polymer recovery>
When the polymer component is recovered from the reaction solution of polyamic acid and polyimide and used, the reaction solution may be put into a poor solvent to precipitate. Examples of the poor solvent used for precipitation include methanol, acetone, hexane, butyl cellsolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, isopropanol, and water. The polymer put into a poor solvent and precipitated can be recovered by filtration and then dried at room temperature or by heating under normal pressure or reduced pressure.
Further, by repeating the operation of re-dissolving the polymer recovered by precipitation in an organic solvent and re-precipitating and recovering it 2 to 10 times, impurities in the polymer can be reduced. At this time, it is preferable to use three or more kinds of poor solvents such as alcohols, ketones, and hydrocarbons as the poor solvent because the efficiency of purification is further improved.

The organic solvent that dissolves the resin component in the reprecipitation recovery step is not particularly limited. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethyl sulfoxide, and tetra. Methylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, dipentene, ethylamylketone, methylnonylketone, methylethylketone, methylisoamylketone, methylisopropylketone, cyclohexanone, ethylenecarbonate , Propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone and the like. Two or more kinds of these solvents may be mixed and used.

[Silicon dioxide]
The composition for forming a flexible device substrate of the present invention may contain silicon dioxide (silica). The silicon dioxide (silica) that can be used is not particularly limited, but silicon dioxide in the form of particles, for example, an average particle diameter of 100 nm or less, for example, 5 nm to 100 nm, preferably 5 nm to 55 nm, and a more transparent thin film can be reproduced with good reproducibility. From the viewpoint of obtaining, it is preferably 5 nm to 50 nm, more preferably 5 nm to 45 nm, still more preferably 5 nm to 35 nm, still more preferably 5 nm to 30 nm.
In the present invention, the average particle size of the silicon dioxide particles is an average particle size value calculated from the specific surface area value measured by the nitrogen adsorption method using the silicon dioxide particles.

In particular, in the present invention, colloidal silica having the above average particle size value can be preferably used, and silica sol can be used as the colloidal silica. As the silica sol, an aqueous silica sol produced by a known method using an aqueous sodium silicate solution as a raw material and an organosilica sol obtained by substituting water as a dispersion medium of the aqueous silica sol with an organic solvent can be used.
Further, an alkoxysilane such as methyl silicate or ethyl silicate is hydrolyzed and condensed in an organic solvent such as alcohol in the presence of a catalyst (for example, an alkaline catalyst such as ammonia, an organic amine compound or sodium hydroxide). Or an organosilica sol obtained by substituting the silica sol with another organic solvent can also be used.
Among these, it is preferable to use an organosilica sol in which the dispersion medium is an organic solvent in the present invention.

Examples of the organic solvent in the above-mentioned organosilica sol include lower alcohols such as methyl alcohol, ethyl alcohol and isopropanol; linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide; N-methyl-2- Cyclic amides such as pyrrolidone; ethers such as γ-butyrolactone; glycols such as ethyl cellosolve and ethylene glycol, acetonitrile and the like can be mentioned. This substitution can be performed by a usual method such as a distillation method or an ultrafiltration method.
The viscosity of the above organosilica sol is about 0.6 mPa · s to 100 mPa · s at 20 ° C.

Examples of commercial products of the above organosilica sol include, for example, trade name MA-ST-S (methanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.) and trade name MT-ST (methanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.). ), Product name MA-ST-UP (methanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), product name MA-ST-M (methanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), product name MA-ST- L (Methanol dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-S (isopropanol dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name IPA-ST (isopropanol dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.) (Manufactured by Co., Ltd.), trade name IPA-ST-UP (isopropanol dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-L (isopropanol dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name IPA -ST-ZL (isopropanol dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name NPC-ST-30 (n-propyl cellosolve dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name PGM-ST (1- Methoxy-2-propanol dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name DMAC-ST (dimethylacetamide dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name XBA-ST (xylene / n-butanol mixed solvent) Dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd., trade name EAC-ST (ethyl acetate dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name PMA-ST (propylene glycol monomethyl ether acetate dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.) (Manufactured by Co., Ltd.), trade name MEK-ST (methyl ethyl ketone dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name MEK-ST-UP (methyl ethyl ketone dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name MEK-ST -L (Methyl ethyl ketone dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.) and trade name MIBK-ST (Methyl isobutyl ketone dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.) and the like can be mentioned, but are not limited thereto.
In the present invention, silicon dioxide, for example, silicon dioxide as mentioned in the above product used as an organosilica sol, may be used as a mixture of two or more.

[Crosslinking agent]
The composition for forming a flexible device substrate of the present invention may further contain a cross-linking agent, and the cross-linking agent used here is a compound composed only of a hydrogen atom, a carbon atom, a nitrogen atom and an oxygen atom. , A cross-linking agent consisting of a compound having two or more groups selected from the group consisting of a hydroxy group, an epoxy group and an alkoxy group having 1 to 5 carbon atoms and having a ring structure. By using such a cross-linking agent, a composition for forming a flexible device substrate, which not only provides a resin thin film having excellent solvent resistance and suitable for a flexible device substrate with good reproducibility, but also has improved storage stability, is realized. can do.
Above all, the total number of hydroxy groups, epoxy groups and alkoxy groups having 1 to 5 carbon atoms per compound in the cross-linking agent is preferably 3 or more from the viewpoint of realizing the solvent resistance of the obtained resin thin film with good reproducibility. From the viewpoint of realizing the flexibility of the obtained resin thin film with good reproducibility, it is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less.

Specific examples of the ring structure of the cross-linking agent include aryl rings such as benzene, nitrogen-containing heteroaryl rings such as pyridine, pyrazine, pyrimidine, pyridazine, 1,3,5-triazine, cyclopentane, cyclohexane, cycloheptane and the like. Cycloalkane ring, piperidine, piperazine, hexahydropyrimidine, hexahydropyridazine, hexahydro-1,3,5-triazine and other cyclic amines can be mentioned.

The number of ring structures per compound in the cross-linking agent is not particularly limited as long as it is 1 or more, but 1 or 2 is selected from the viewpoint of ensuring the solubility of the cross-linking agent in the solvent and obtaining a highly flat resin thin film. preferable.
When two or more ring structures are present, the ring structures may be condensed with each other, and an alkane having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, and a propane-2,2-diyl group- The ring structures may be bonded to each other via a linking group such as a diyl group.

The molecular weight of the cross-linking agent is not particularly limited as long as it has a cross-linking ability and is soluble in the solvent used, but the solvent resistance of the obtained resin thin film, the solubility of the cross-linking agent itself in an organic solvent, and easy availability. Considering the property, price, etc., it is preferably about 100 to 500, and more preferably about 150 to 400.

The cross-linking agent may further have a group that can be derived from a hydrogen atom, a carbon atom, a nitrogen atom and an oxygen atom, such as a ketone group and an ester group (bond).

Preferred examples of the cross-linking agent include compounds represented by any of the following formulas (K1) to (K5), and one of the preferred embodiments of the formula (K4) is represented by the formula (K4-1). As one of the preferred embodiments of the formula (K5), the compound represented by the formula (K5-1) can be mentioned.

In the above formula, each of A ¹ and A ² independently represents an alkane-diyl group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, and a propane-2,2-diyl group. Among them, A ¹ is preferably a methylene group or an ethylene group, more preferably a methylene group, and A ² is preferably a methylene group or a propane-2,2-diyl group.

Each X is independently of a hydroxy group, an epoxy group (oxa-cyclopropyl group), or a methoxy group, an ethoxy group, a 1-propyloxy group, an isopropyloxy group, a 1-butyloxy group, a t-butyloxy group, etc. Represents an alkoxy group having 1 to 5 carbon atoms.
Among them, considering the availability, price, etc. of the cross-linking agent, X is preferably an epoxy group in the formulas (K1) and (K5), and has 1 to 5 carbon atoms in the formulas (K2) and (K3). An alkoxy group is preferable, and a hydroxy group is preferable in the formula (K4).

In the formula (K4), each n indicates the number of-(A ¹ -X) groups bonded to the benzene ring, and is an integer of 1 to 5 independently of each other, preferably 2 to 3, and more preferably. It is 3.

In each compound, each A ¹ is preferably all the same group, and each X is preferably all the same group.

The compounds represented by the above formulas (K1) to (K5) include skeleton compounds such as aryl compounds, heteroaryl compounds and cyclic amines having the same ring structure as the ring structure in each of these compounds, and epoxyalkyl halide compounds. It can be obtained by reacting with an alkoxyhalide compound or the like by a carbon-carbon coupling reaction or an N-alkylation reaction, or by hydrolyzing an alkoxy moiety of the result.

As the cross-linking agent, a commercially available product may be used, or one synthesized by a known synthetic method may be used.
Commercially available products include CYMEL® 300, 301, 303LF, 303ULF, 304, 350, 3745, XW3106, MM-100, 323, 325, 327, 328, etc. 385, 370, 373, 380, 1116, 1130, 1133, 1141, 1161, 1168, 3020, 202, 203, 1156, MB-94, MB- 96, MB-98, 247-10, 651, 658, 683, 688, 1158, MB-14, MI-12-I, MI-97-IX, U-65. , UM-15, U-80, U-21-511, U-21-510, U-216-8, U-227-8, U-1050-10, U-1052 -8, U-1054, U-610, U-640, UB-24-BX, UB-26-BX, UB-90-BX, UB-25-BE, UB-30 -B, U-662, U-663, U-1051, UI-19-I, UI-19-IE, UI-21-E, UI-27-EI, U-38. -I, UI-20-E 659, 1123, 1125, 5010, 1170, 1172, NF3041, NF2000, etc. (all made by Hewlett); TEPIC® V, S , HP, L, PAS, VL, UC (above, manufactured by Nissan Chemical Industry Co., Ltd.), TM-BIP-A (manufactured by Asahi Organic Materials Industry Co., Ltd.), 1, 3, 4, 6 -Tetrakiss (methoxymethyl) glycol uryl (hereinafter abbreviated as TMG) (manufactured by Tokyo Kasei Kogyo Co., Ltd.), 4,4'-methylenebis (N, N-diglycidylaniline) (manufactured by Aldrich), HP-4032D, HP-7200L, HP-7200, HP-7200H, HP-7200HH, HP-7200HHH, HP-4700, HP-4770, HP-5000, HP-46000, HP-4710, EXA-4850-150, EXA-4850- 1000, EXA-4816, HP-820 (DIC Co., Ltd.), TG-G (Shikoku Kasei Kogyo Co., Ltd.) and the like can be mentioned.

Hereinafter, preferred specific examples of the cross-linking agent will be given, but the present invention is not limited thereto.

The blending amount of the cross-linking agent cannot be unconditionally specified because it is appropriately determined depending on the type of the cross-linking agent and the like, but it is usually obtained with respect to the mass of the polyimide or the total mass of the polyimide and the silicon dioxide. From the viewpoint of ensuring the flexibility of the resin thin film to be obtained and suppressing weakening, it is 50% by mass or less, preferably 100% by mass or less, and from the viewpoint of ensuring the solvent resistance of the obtained resin thin film, 0.1% by mass. As mentioned above, it is preferably 1% by mass or more.

[Organic solvent]
The composition for forming a resin thin film of the present invention contains an organic solvent in addition to the polyimide, arbitrary silicon dioxide, a cross-linking agent and the like. The organic solvent is not particularly limited, and examples thereof include the same as the specific examples of the reaction solvent used in the preparation of the polyamic acid and the polyimide. More specifically, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone, γ- Butyrolactone and the like can be mentioned. The organic solvent may be used alone or in combination of two or more.
Among these, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and γ-butyrolactone are preferable in consideration of obtaining a resin thin film having high flatness with good reproducibility.

[Composition for forming a flexible device substrate]
The present invention is a composition for forming a flexible device substrate, which contains the polyimide, an organic solvent, silicon dioxide, a cross-linking agent, and the like, if desired. Here, the composition for forming a flexible device substrate of the present invention is uniform and does not allow phase separation.
When silicon dioxide is contained in the composition for forming a flexible device substrate of the present invention, the compounding ratio of the polyimide and the silicon dioxide may be a mass ratio of polyimide: silicon dioxide = 10: 1 to 1:10. It is preferable, more preferably 8: 2 to 2: 8, for example, 7: 3 to 3: 7.
The solid content in the composition for forming a flexible device substrate of the present invention is usually in the range of 0.5 to 30% by mass, but is preferably 5% by mass or more and 20% by mass from the viewpoint of film uniformity. It is as follows. The solid content means the remaining components excluding the solvent from all the components constituting the composition for forming a flexible device substrate.
The viscosity of the composition for forming a flexible device substrate is appropriately determined in consideration of the coating method used, the thickness of the resin thin film to be produced, and the like, but is usually 1 to 50,000 mPa · s at 25 ° C. ..

In addition, various organic or inorganic small molecule or polymer compounds may be blended in the composition for forming a flexible device substrate of the present invention in order to impart processing characteristics and various functionalities. For example, catalysts, defoamers, leveling agents, surfactants, dyes, plasticizers, fine particles, coupling agents, sensitizers and the like can be used. For example, a catalyst may be added for the purpose of reducing the retardation of the resin thin film or the coefficient of linear expansion.
The composition for forming a flexible device substrate of the present invention can be obtained by dissolving the polyimide obtained by the above-mentioned method, silicon dioxide, a cross-linking agent and the like, if desired, in the above-mentioned organic solvent, and after the polyimide is prepared. Silicon dioxide, a cross-linking agent, or the like may be added to the reaction solution, if desired, and the organic solvent may be further added if desired.

[Flexible device board]
By applying the composition for forming a flexible device substrate of the present invention described above to a substrate, drying and heating, the organic solvent is removed, and the heat resistance is excellent, the retardation is low, the flexibility is excellent, and the transparency is further increased. It is possible to obtain a resin thin film, that is, a flexible device substrate, which can be easily peeled off from the glass carrier by the LLO method while maintaining the excellent performance of being excellent.
The present invention also relates to the flexible device substrate, that is, the flexible device substrate containing the polyimide and, if desired, silicon dioxide, a cross-linking agent, etc., that is, a cured product of the composition for forming a flexible device substrate of the present invention. Is the subject of.

Examples of the base material used for manufacturing the flexible device substrate (resin thin film) include plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetyl cellulose, ABS, AS, norbornene resin, etc.) and metals. , Stainless steel (SUS), wood, paper, glass, silicon wafers, slate and the like.
In particular, when applied as a flexible device substrate, it is preferable that the base material to be applied is glass or a silicon wafer from the viewpoint that existing equipment can be used, and the obtained flexible device substrate exhibits good peelability. Therefore, it is more preferable to use glass. The coefficient of linear expansion of the applied base material is preferably 40 ppm / ° C. or less, more preferably 30 ppm / ° C. or less, from the viewpoint of warping of the base material after coating.

The method for applying the composition for forming a flexible device substrate to the substrate is not particularly limited, but for example, a cast coating method, a spin coating method, a blade coating method, a dip coating method, a roll coating method, and a bar coating method. , Die-coating method, inkjet method, printing method (letter plate, intaglio, lithographic plate, screen printing, etc.) and the like, and these can be appropriately used depending on the purpose.

The heating temperature is preferably 300 ° C. or lower. If the temperature exceeds 300 ° C., the obtained resin thin film becomes brittle, and it may not be possible to obtain a resin thin film particularly suitable for display substrate applications.
Considering the heat resistance and linear expansion coefficient characteristics of the obtained resin thin film, the applied composition for forming a flexible device substrate is heated at 40 ° C. to 100 ° C. for 5 minutes to 2 hours, and then the heating temperature is gradually increased. It is desirable to raise the temperature and finally heat at 175 ° C. to 280 ° C. for 30 minutes to 2 hours. As described above, by heating at a temperature of two or more steps, that is, a step of drying the solvent and a step of promoting molecular orientation, low thermal expansion characteristics can be exhibited with better reproducibility.
In particular, the applied composition for forming a flexible device substrate is heated at 40 ° C. to 100 ° C. for 5 minutes to 2 hours, then heated at over 100 ° C. to 175 ° C. for 5 minutes to 2 hours, and then at 175 ° C. to 280 ° C. It is preferable to heat for 5 minutes to 2 hours.
Examples of the appliance used for heating include a hot plate and an oven. The heating atmosphere may be under air or under an inert gas such as nitrogen, under normal pressure or under reduced pressure, and different pressures may be applied at each stage of heating. May be.

The thickness of the resin thin film is appropriately determined in the range of about 1 to 200 μm in consideration of the type of flexible device, but is usually 1 to 60 μm, especially when it is assumed to be used as a substrate for a flexible display. The thickness is preferably about 5 to 50 μm, and the thickness of the coating film before heating is adjusted to form a resin thin film having a desired thickness.
The method of peeling the resin thin film thus formed from the base material is not particularly limited, and the resin thin film is cooled together with the base material, a cut is made in the thin film, and tension is applied via a roll. And the method of peeling off.
In particular, in the present invention, a laser lift-off (LLO) method can be adopted as a method for peeling the resin thin film from the substrate. That is, by irradiating the base material with light rays of a specific wavelength from the surface opposite to the surface on which the resin thin film of the base material is formed, the light rays of the wavelength pass through the base material (for example, a glass carrier), and the base material is used. The resin thin film can be peeled off from the base material by absorbing this light ray only by the polyimide in the vicinity and evaporating the polyimide in the portion.
The laser light used for peeling the resin thin film from the substrate by the laser lift-off method is not particularly limited, but an excimer laser is preferable, and specifically, the oscillation wavelengths are ArF (193 nm), KrF (248 nm), and XeCl (308 nm). ), XeF (353 nm) and the like, but XeCl (308 nm) is particularly preferable.
The energy density of the laser light to be irradiated usually includes a range of 200 mJ / cm ² to 500 mJ / cm ² , for example, a range of 260 mJ / cm ² to 420 mJ / cm ² and 317 mJ / cm ² to 420 mJ /. Examples thereof include a range of cm ² and a range of 260 mJ / cm ² to 330 mJ / cm ² , a range of 317 mJ / cm ² to 330 mJ / cm ² , and a range of 260 mJ / cm ² to 317 mJ / cm ² .

The resin thin film according to a preferred embodiment of the present invention thus obtained can realize high transparency with a light transmittance of 84% or more at a wavelength of 550 nm. On the other hand, the light transmittance at a wavelength of 308 nm is 1% or less, that is, sufficient light absorption at the wavelength that enables peeling of the resin thin film from the substrate to which the laser lift-off method is applied can be achieved.
Further, the resin thin film can have a linear expansion coefficient of 40 ppm / ° C. or less, particularly 10 ppm / ° C. to 35 ppm / ° C. at 30 ° C. to 220 ° C., and is excellent in dimensional stability during heating. Is.
Further, the resin thin film has an in-plane retardation R ₀ represented by the product of birefringence (difference between two orthogonal refractive indexes in the plane) and the film thickness when the wavelength of the incident light is 590 nm, and the thickness. As the average value of the two phase differences obtained by multiplying the two birefringences (differences between the two in-plane refractive indexes and the refractive index in the thickness direction) when viewed from the cross section in the vertical direction by the film thickness. It is characterized in that the represented thickness-direction retardation R _th is small.

Since the resin thin film described above has the above-mentioned characteristics, it satisfies each condition required as a base film of a flexible device substrate, and is particularly preferably used as a base film of a flexible device, particularly a substrate of a flexible display. can.
When the average film thickness is 15 to 40 μm, the resin thin film has a thickness-direction retardation R _th of 700 nm or less, for example 450 nm or less, or 1 to 410 nm, and an in-plane retardation R ₀ of less than 4.5, for example. For example, it is 0.1 to 4.2, and the birefringence index Δn is smaller than 0.001.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

The meanings of the abbreviations used in the following examples are as follows.
<Acid dianhydride>
BODAxx: Bicyclo [2,2,2] octane-2,3,5,6-tetracarboxylic dianhydride BTDA: 3,3', 4,4'-benzophenone tetracarboxylic dianhydride s-BPDA: 3 , 3', 4,4'-biphenyltetracarboxylic dianhydride CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride <diamine>
TFMB: 2,2'-bis (trifluoromethyl) benzidine <organic solvent>
GBL: γ-Butyrolactone

In the examples, the devices and conditions used for sample preparation and analysis and evaluation of physical properties are as follows.
1) Measurement of number average molecular weight and weight average molecular weight The number average molecular weight (hereinafter abbreviated as Mn) and weight average molecular weight (hereinafter abbreviated as Mw) of the polymer are determined by the equipment: Showa Denko KK, Showdex GPC-101, Measurement was performed under the conditions of columns: KD803 and KD805, column temperature: 50 ° C., elution solvent: DMF, flow rate: 1.5 ml / min, and molecular weight line: standard polystyrene.
2) Linear expansion coefficient (CTE)
Using TMA Q400 manufactured by TA Instruments, the resin thin film is cut into a size of 5 mm in width and 16 mm in length, first heated at 10 ° C / min and heated to 50 to 350 ° C (first heating), and then 10 Linear expansion of the second heating at 50 ° C to 200 ° C when the temperature is lowered at ° C./min, cooled to 50 ° C, then heated at 10 ° C / min and heated to 50 to 420 ° C (second heating). It was determined by measuring the value of the coefficient (CTE [ppm / ° C.]) and the linear expansion coefficient (CTE [ppm / ° C.]) at 200 ° C. to 250 ° C. A load of 0.05 N was applied through the first heating, cooling and the second heating.
3) 5% weight loss temperature (Td _5% )
The 5% weight loss temperature (Td _5% [° C.]) is measured by raising the temperature of about 5 to 10 mg of the resin thin film in nitrogen to 50 to 800 ° C. at 10 ° C./min using TGA Q500 manufactured by TA Instruments. I asked for it.
4) Light transmittance (transparency) (T _308nm , T _550nm ) and CIE b value (CIE b ^* )
For the light transmittance (T _{308 nm} , T _{550 nm} [%]) and CIE b value (CIE b ^* ) at wavelengths of 308 nm and 550 nm, refer to the SA4000 spectrometer manufactured by Nippon Denshoku Kogyo Co., Ltd. at room temperature. Measurements were made as air.
5) Ritalization (R _th , R ₀ )
Thickness direction retardation (R _th ) and in-plane retardation (R ₀ ) were measured at room temperature using KOBURA 2100ADH manufactured by Oji Measuring Instruments Co., Ltd.
The thickness direction retardation (R _th ) and the in-plane retardation (R ₀ ) are calculated by the following formulas.
R ₀ = (Nx-Ny) x d = ΔNxy x d
R _th = [(Nx + Ny) /2-Nz] × d = [(ΔNxz × d) + (ΔNyz × d) / 2
Nx, Ny: Two orthogonal refractive indexes in the plane (Nx> Ny, Nx is also referred to as a slow axis, Ny is also referred to as a phase advance axis).
Nz: Refractive index in the thickness (perpendicular) direction with respect to the plane d: Film thickness ΔNxy: Difference between two refractive indexes in the plane (Nx-Ny) (birefringence)
ΔNxz: Difference between in-plane refractive index Nx and refractive index Nz in the thickness direction (birefringence)
ΔNyz: Difference between the in-plane refractive index Ny and the refractive index Nz in the thickness direction (birefringence)
6) Birefringence (Δn)
Using the value of the thickness direction retardation (R _th ) obtained by the above-mentioned <6) retardation>, it was calculated by the following formula.
Δn = [R _th / d (film thickness)] / 1000
7) Film thickness The film thickness of the obtained resin thin film was measured with a thickness gauge manufactured by Teclock Co., Ltd.

[1] Preparation Example Preparation Example 1: Preparation of silica sol (GBL-M) In a 1000 mL round-bottom flask, methanol-dispersed silica sol manufactured by Nissan Chemical Industry Co., Ltd .: MA-ST-M 350 g (silica solid content concentration: 40.4) Mass%) and 419 g of γ-butyl lactone were added. Then, the flask was connected to a vacuum evaporator, the inside of the flask was depressurized, and the flask was immersed in a warm water bath at about 35 ° C. for 20 to 50 minutes. 560.3 g was obtained (silica solid content concentration: 25.25% by mass).

[2] Synthesis example Synthesis example 1: Synthesis of polyimide I (PI-I) TFMB 6.4046 g (0.02 mol) in a 250 mL three-necked flask equipped with Dean-Stark, nitrogen inlet / outlet, and mechanical stirrer. ) Was added, and immediately after that, 22.24 g of GBL was added and stirring was started. Immediately after adding 25005 g (0.01 mol) of BODAxx after the diamine was completely dissolved in the solvent, 6.67 g of GBL and 0.222 g of 1-ethylpiperidine were added and 3.5 hours under nitrogen. It was heated to 140 ° C. Then, immediately after adding 0.6445 g (0.002 mol) of BTDA, 6.67 g of GBL was added and reacted under nitrogen for 0.5 hours. Then, immediately after adding 1.5688 g (0.008 mol) of CBDA, 8.89 g of GBL and 0.222 g of 1-ethylpiperidine were added, the temperature was raised to 180 ° C., and the reaction was carried out under nitrogen for 7 hours. Finally, heating was stopped, the reaction solution was diluted to 10%, and stirring was continued overnight. The polyimide reaction solution was added to 500 g of methanol and stirred for 30 minutes, and then the polyimide was purified by filtering the polyimide solid, the polyimide solid was stirred in 500 g of methanol for 30 minutes, and then the polyimide solid was filtered. The purification procedure of stirring and filtering the polyimide solid was repeated three times. The methanol residue in the polyimide was removed by drying in a vacuum oven at 150 ° C. for 8 hours to finally obtain 9.563 g of dried polyimide I, with a weight percent yield of 86.01%. (Mw = 161,774, Mn = 59,451).

Synthesis Example 2: Synthesis of Polyimide II (PI-II) Polyimide by performing the same operation as in Synthesis Example 1 except that s-BPDA (0.002 mol) was used instead of BTDA (0.002 mol). II (PI-II) was obtained.

Synthesis Example 3: Synthesis of Polyimide A (PI-A) 25.61 g (0.08 mol) of TFMB was placed in a 250 mL reaction three-necked flask equipped with a nitrogen inlet / outlet, a mechanical stirrer and a cooler. Then, 173.86 g of GBL was added and stirring was started. Immediately after the diamine was completely dissolved in the solvent, 10 g (0.04 mol) of stirred BODAxx, 7.84 g (0.04 mol) of CBDA and 43.4 g of GBL were added and heated to 140 ° C. under nitrogen. .. Then, 0.348 g of 1-ethylpiperidine was added into the solution, and the mixture was heated to 180 ° C. under nitrogen for 7 hours. Finally, heating was stopped, the reaction solution was diluted to 10% and stirring was maintained overnight. The polyimide reaction solution was added to 2000 g of methanol and stirred for 30 minutes, and then the polyimide was purified by filtering the polyimide solid, and then the polyimide solid was stirred in 2000 g of methanol for 30 minutes and the polyimide solid was filtered. The purification procedure of stirring and filtering the polyimide solid was repeated three times. The methanol residue in the polyimide was removed by drying in a vacuum oven at 150 ° C. for 8 hours to finally obtain 31.16 g of dried polyimide A, but the weight percent yield of the polyimide was 74% (Mw). = 169,802, Mn = 55,308).

[3] Composition and film formation Example 1: Polyimide I resin thin film At room temperature, 1 g of polyimide (PI-I) of Synthesis Example 1 was dissolved in a GBL solvent so as to be 10% by mass through a 5 μm filter. It was slowly pressurized and filtered. Then, the solution is coated on a glass substrate and fired in an air atmosphere at a temperature of 50 ° C. for 30 minutes, at 140 ° C. for 30 minutes and at 200 ° C. for 60 minutes, and then in a vacuum atmosphere of −99 kpa at 280 ° C. The resin thin film was obtained by firing for 60 minutes.

Example 2: Polyimide I / silica sol composite resin thin film At room temperature, 1 g of the polyimide (PI-I) of Synthesis Example 1 was dissolved in a GBL solvent so as to be 10% by mass, and slowly pressure-filtered through a 5 μm filter. .. Then, the filtrate is added to 9.241 g of silica sol (GBL-M) (18-23 nm SiO ₂ nanoparticles dispersed in GBL at 25.25%), mixed for 30 minutes, and then left in a stationary state. Maintained in the evening. Then, the solution is coated on a glass substrate and fired under air at a temperature of 50 ° C. for 30 minutes, at 140 ° C. for 30 minutes and at 200 ° C. for 60 minutes, and in a vacuum atmosphere of −99 kpa at 280 ° C. for 60 minutes. A resin thin film was obtained.

Example 3: Polyimide II resin thin film At room temperature, 1 g of the polyimide (PI-II) of Synthesis Example 2 was dissolved in a GBL solvent so as to have a mass of 10% by mass, and the mixture was slowly pressure-filtered through a 5 μm filter. Then, the solution is coated on a glass substrate and fired in an air atmosphere at a temperature of 50 ° C. for 30 minutes, at 140 ° C. for 30 minutes and at 200 ° C. for 60 minutes, and then in a vacuum atmosphere of −99 kpa at 280 ° C. The resin thin film was obtained by firing for 60 minutes.

Example 4: Polyimide II / silica sol composite resin thin film At room temperature, 1 g of the polyimide (PI-II) of Synthesis Example 2 was dissolved in a GBL solvent so as to be 10% by mass, and slowly pressure-filtered through a 5 μm filter. .. Then, the filtrate is added to 9.241 g of silica sol (GBL-M) (18-23 nm SiO ₂ nanoparticles dispersed in GBL at 25.25%), mixed for 30 minutes, and then left in a stationary state. Maintained in the evening. Then, the solution is coated on a glass substrate and fired under air at a temperature of 50 ° C. for 30 minutes, at 140 ° C. for 30 minutes and at 200 ° C. for 60 minutes, and in a vacuum atmosphere of −99 kpa at 280 ° C. for 60 minutes. A resin thin film was obtained.

Example 5: Polyimide A resin thin film At room temperature, 1 g of the polyimide (PI-A) of Synthesis Example 3 dissolved in a GBL solvent so as to be 10% by mass was slowly pressure-filtered through a 5 μm filter. Then, the solution was coated on a glass substrate and fired at a temperature of 50 ° C. for 30 minutes, 140 ° C. for 30 minutes and 200 ° C. for 60 minutes under an air atmosphere to obtain a resin thin film.

Example 6: Polyimide A / silica sol composite resin thin film At room temperature, 1 g of the polyimide (PI-A) of Synthesis Example 3 was dissolved in a GBL solvent so as to be 10% by mass, and slowly pressure-filtered through a 5 μm filter. .. Then, the filtrate is added to 9.241 g of silica sol (GBL-M) (18-23 nm SiO ₂ nanoparticles dispersed in GBL at 25.25%), mixed for 30 minutes, and then left in a stationary state. Maintained in the evening. Then, the solution is coated on a glass substrate and fired under air at a temperature of 50 ° C. for 30 minutes, at 140 ° C. for 30 minutes and at 200 ° C. for 60 minutes, and in a vacuum atmosphere of −99 kpa at 280 ° C. for 60 minutes. A resin thin film was obtained.

[4] Evaluation of Resin Thin Films The resin thin films of Examples 1 to 6 prepared by the above procedure were peeled off by mechanical cutting and used for subsequent evaluation.
Thermal performance and optical performance of each resin thin film, that is, linear expansion coefficient (50 to 200 ° C: CTE [ppm / ° C]), 5% weight loss temperature (Td _5% [° C]), light transmittance (T _{308 nm} ). [%], T _{550 nm} [%]), CIE b value (yellow evaluation: CIE b ^* ), and retardation (R _th [nm], _Ro [nm]) were evaluated according to the above procedure. The results are shown in Table 1.

As shown in Table 1, the resin thin films of the present invention shown in Examples 1 to 4 have a low linear expansion coefficient [ppm / ° C.] (50 to 200 ° C.) and a light transmittance at 550 nm after curing [ %] Was good, the light transmittance [%] at 308 nm was low, and it was confirmed that the retardation was suppressed to a low value.
The resin thin films of the present invention obtained in Examples 1 to 4 do not crack even when they are held by both hands and bent at an acute angle (about 30 degrees), and the high flexibility required for a flexible display substrate is high. Also had.

[5] Peeling of Resin Thin Film by LLO Method It was evaluated whether or not each of the resin thin films of Example 1, Example 3, Example 5 and Example 6 produced by the above procedure was peeled by the LLO method.
The following conditions were adopted as the LLO method.
Laser light source: Maxima laser XeCl (308nm)
Energy density: 200mJ / cm ² , 260mJ / cm ² , 317mJ / cm ² , 330mJ / cm ² , 420mJ / cm ²
Stage movement speed: 7.8 mm / sec Laser beam size: 14 mm x 1.3 mm (size at maximum energy: 7.8 mm x 1.3 mm), laser light overlapping scanning range is 80%
The results are shown in Table 2.
In the table, ◯ indicates that the resin thin film was peeled off, and × indicates that the resin thin film was not peeled off.

As shown in Table 2, it was confirmed that the resin thin films of the present invention shown in Examples 1 and 3 can be peeled off by the LLO method. On the other hand, the resin thin film of Example 5 formed from the polyimide (PI-A) synthesized without using the aromatic tetracarboxylic acid dianhydride represented by the formula (D1) was not peeled off under the same conditions. Further, the resin thin film of Example 6 formed by adding SiO ₂ to PI-A was also not peeled off.

Claims (10)

A reaction product of a tetracarboxylic acid dianhydride component containing an alicyclic tetracarboxylic acid dianhydride and an aromatic tetracarboxylic acid dianhydride represented by the formula (D1), and a diamine component containing a fluorine-containing aromatic diamine. Contains polyimide, which is an organic solvent, and an organic solvent .
The alicyclic tetracarboxylic dianhydride comprises bicyclo [2,2,2] octane-2,3,5,6-tetracarboxylic dianhydride.
A composition for forming a flexible device substrate .

(In the formula, E represents a single bond, a carbonyl group, an oxygen atom, a sulfur atom, SO or SO _2. ) The composition for forming a flexible device substrate according to claim 1, wherein the alicyclic tetracarboxylic dianhydride further comprises an alicyclic tetracarboxylic dianhydride represented by the formula (C1).

[In the formula, B ¹ is the formula (X-1) , (X-2), (X-3), (X-4), (X-5), (X-7), (X-8). , (X-9), (X-10), (X-11), and (X-12) represent a tetravalent group selected from the group.

(In the equation, multiple Rs represent hydrogen atoms or methyl groups independently of each other, and * represents a bond.)] The composition for forming a flexible device substrate according to claim 1 or 2, wherein the fluorine-containing aromatic diamine contains a diamine represented by the formula (A1).

(In the formula, B ² represents a divalent group selected from the group consisting of formulas (Y-1) to (Y-34).)

(In the formula, * represents a bond.) The tetracarboxylic dianhydride component is an aromatic tetracarboxylic dianhydride represented by the formula (D1) in an amount of 1 mol% to 30 mol% based on the total number of moles of the tetracarboxylic dianhydride component. The composition for forming a flexible device substrate according to any one of claims 1 to 3, which comprises. The flexible device substrate formation according to any one of claims 1 to 4, further comprising silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method. Composition for. The composition for forming a flexible device substrate according to claim 5, wherein the mass ratio of the polyimide and the silicon dioxide particles is 7: 3 to 3: 7. The composition for forming a flexible device substrate according to claim 5 or 6, wherein the average particle size is 60 nm or less. The composition for forming a flexible device substrate according to any one of claims 1 to 7, which is a composition for forming a substrate of a flexible device for use in a laser lift-off method. A flexible device substrate produced by using the composition for forming a flexible device substrate according to any one of claims 1 to 7. A step of applying the composition for forming a flexible device substrate according to any one of claims 1 to 7 to a substrate, drying and heating to form a flexible device substrate.
A method for manufacturing a flexible device substrate, which comprises a peeling step of peeling the flexible device substrate from the substrate by a laser lift-off method.