WO2017119450A1 - Composition for forming substrate for flexible devices - Google Patents

Abstract

[Problem] The purpose of the present invention is to provide a composition for forming a substrate for flexible devices, which forms a resin thin film characterized by having excellent heat resistance and low retardation, especially a resin thin film that is suitable as a substrate for flexible devices, and which forms a resin thin film that absorbs light beams having a specific wavelength, thereby enabling the application of a laser lift-off method. [Solution] A composition for forming a substrate for flexible devices, which contains a polyimide, titanium dioxide particles having particle diameters of from 3 nm to 200 nm, silicon dioxide particles having an average particle diameter of 100 nm or less as calculated from the specific surface area that is determined by a nitrogen adsorption method, and an organic solvent; and a resin thin film which is formed from this composition for forming a substrate for flexible devices.

Description

Composition for forming flexible device substrate

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

In recent years, with rapid advances in electronics such as liquid crystal displays and organic electroluminescence displays, it has become necessary to make devices thinner and 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 the glass material with a flexible and lightweight resin material, the device itself can be made thinner and lighter. And flexibility.
Under such circumstances, polyimide is attracting attention as an alternative material for glass. And the polyimide for the said use requires transparency similar to glass in most cases in addition to flexibility. In order to realize these characteristics, semi-alicyclic polyimides and fully alicyclic polyimides obtained by using alicyclic diamine components or alicyclic anhydride components as raw materials have been reported (for example, Patent Documents 1 to 4). 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 using the laser lift-off method (LLO method) that has been used in the manufacture of high-brightness LEDs, three-dimensional semiconductor packages, and the like. (For example, Non-Patent Document 1).
In manufacturing a flexible display, a polymer substrate made of polyimide or the like is provided on a glass carrier, and then a circuit or the like including an electrode or the like is formed on the substrate. Finally, the substrate is peeled off from the glass carrier together with the circuit or the like. There is a need. In this peeling step, the LLO method is adopted, that is, when a glass carrier is irradiated with a light beam having a wavelength of 308 nm from the surface opposite to the surface on which a circuit or the like is formed, the light beam with the wavelength passes through the glass carrier, Only the nearby polymer (polyimide) absorbs this light and evaporates (sublimates). As a result, it has been reported that peeling of the substrate from the glass carrier can be performed selectively without affecting the circuit or the like provided on the substrate, which determines the performance of the display.

JP 2013-147599 A JP 2014-114429 A 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 increasingly used as a substrate peeling method that is extremely superior in the manufacture of flexible displays. As the practicality of flexible displays and the realization of mass production increase, the demand for polymer substrates for flexible displays to which the LLO method can be applied will increase.
In order to be able to adopt the LLO method in the manufacture of a flexible display, it is required that the polymer substrate absorbs light having a specific wavelength. However, the semi-alicyclic polyimide and the fully alicyclic polyimide, which have been proposed as flexible display substrate materials so far, include an alicyclic moiety, so that the absorption of light in the visible light region is suppressed and the transparency is improved. Although excellent, absorption of light in the ultraviolet region is also suppressed, and in many cases, light in the ultraviolet region (for example, 308 nm) that makes it possible to apply the LLO method is not sufficiently absorbed.
Because of such a trade-off relationship, the LLO method is often not applicable to existing materials including semi-alicyclic polyimides and fully alicyclic polyimides. Therefore, in the field of flexible displays, absorption in the visible light region is suppressed and transparency is sufficiently excellent, and light of a specific wavelength (for example, 308 nm) that can be applied to the LLO method is sufficiently absorbed. There is a need for a substrate material having

The present invention has been made in view of such circumstances, and is excellent not only in heat resistance and flexibility, but also as a base film of a flexible device substrate such as a flexible display substrate having a feature of low retardation. The present invention provides a composition for forming a flexible device substrate that gives a resin thin film having performance, and in particular a thin film capable of sufficiently absorbing light of a specific wavelength (308 nm) to which a laser lift-off method can be applied while ensuring transparency in the visible light region. An object of the present invention is to provide a composition for forming a flexible device substrate that can form a film.

As a result of intensive studies to achieve the above object, the present inventors have obtained a resin thin film in which titanium dioxide particles and silicon dioxide particles are blended with polyimide having an alicyclic skeleton in the main chain, and has excellent heat resistance, It has low retardation and also has the characteristics of excellent flexibility, and by making the blending amount of the silicon dioxide within a predetermined range, it has excellent heat resistance, low retardation, excellent flexibility, and transparency. In particular, by blending a specific amount of the titanium dioxide particles, it is possible to realize a resin thin film that can sufficiently absorb light of a specific wavelength that can apply the LLO method while ensuring the transparency. The present invention has been completed by finding that it can be suitably used for substrates for flexible devices such as flexible displays.

〔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７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５観点または請求項６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８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１観点乃至第７観点のうちいずれか一項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、前記二酸化ケイ素粒子の平均粒子径が、６０ｎｍ以下である、第１観点乃至第８観点のうちいずれか一項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１０観点として、レーザーリフトオフ法を適用する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９観点のうちいずれか一項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１１観点として、第１観点乃至第１０観点のうちいずれか一項に記載のフレキシブルデバイス基板形成用組成物から形成されるフレキシブルデバイス基板に関する。
　第１２観点として、第１観点乃至第１０観点のうちいずれか一項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 provides, as a first aspect, a polyimide having an alicyclic skeleton in the main chain,
Titanium dioxide particles having a particle diameter of 3 nm to 200 nm,
The present invention relates to a composition for forming a flexible device substrate, comprising silicon dioxide particles having an average particle diameter of 100 nm or less calculated from a specific surface area value measured by a nitrogen adsorption method, and an organic solvent.
As a second aspect, the titanium dioxide particles are in an amount of 0.1% by mass or more and 20% by mass or less based on a total mass of the polyimide, the titanium dioxide particles, and the silicon dioxide particles. The present invention relates to a composition for forming a flexible device substrate.
As a third aspect, a compound further comprising only a hydrogen atom, a carbon atom, a nitrogen atom and an oxygen atom, wherein the group is selected from the group consisting of a hydroxy group, an epoxy group and an alkoxy group having 1 to 5 carbon atoms. A cross-linking agent comprising a compound having two or more and having a cyclic structure,
It is related with the composition for flexible device board | substrate formation as described in a 1st viewpoint.
As a 4th viewpoint, the said titanium dioxide particle is the quantity of 3 mass% or more and 16 mass% or less with respect to the total mass of the said polyimide, the said titanium dioxide particle, and the said silicon dioxide particle, The flexible device as described in a 3rd viewpoint. The present invention relates to a composition for forming a substrate.
As a fifth aspect, the polyimide imidizes a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a diamine component containing a fluorine-containing aromatic diamine. It is related with the composition for flexible device board | substrate formation as described in any one among the 1st viewpoint thru | or 4th viewpoint which is the polyimide obtained.
As a 6th viewpoint, the said alicyclic tetracarboxylic dianhydride is related with the composition for flexible device board | substrate formation as described in a 5th viewpoint containing the tetracarboxylic dianhydride represented by Formula (C1).

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

(In the formula, a plurality of R's independently represent a hydrogen atom or a methyl group, and * represents a bond.)
As a 7th viewpoint, the said fluorine-containing aromatic diamine is related with the composition for flexible device board | substrate formation of the 5th viewpoint or Claim 6 containing the diamine represented by a formula (A1).

(Wherein 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 an eighth aspect, the composition for forming a flexible device substrate according to any one of the first aspect to the seventh aspect, wherein a mass ratio of the polyimide and the silicon dioxide particles is 7: 3 to 3: 7. About.
As a 9th viewpoint, the average particle diameter of the said silicon dioxide particle is related with the composition for flexible device board | substrate formation as described in any one among the 1st viewpoint thru | or 8th viewpoints which are 60 nm or less.
As a 10th viewpoint, it is related with the composition for flexible device board | substrate formation as described in any one of the 1st viewpoint thru | or the 9th viewpoint which is a board | substrate formation composition of the flexible device which applies a laser lift-off method.
As an 11th viewpoint, it is related with the flexible device board | substrate formed from the composition for flexible device board | substrate formation as described in any one among a 1st viewpoint thru | or a 10th viewpoint.
As a twelfth aspect, a step of applying the flexible device substrate forming composition according to any one of the first aspect to the tenth aspect to a base material, drying and heating to form a flexible device substrate,
The present invention relates to a method for manufacturing a flexible device substrate, including a peeling step of peeling the flexible device substrate from the base material by a laser lift-off method.

According to the composition for forming a flexible device substrate according to the present invention, it has a low coefficient of linear expansion, excellent heat resistance, high transparency and low retardation, and further excellent flexibility, particularly application of the laser lift-off method. It is possible to form a substrate for a flexible device such as a flexible display that can sufficiently absorb a light beam having a specific wavelength (308 nm) that can be reproduced with good reproducibility.
In addition, the flexible device substrate according to the present invention has various characteristics required for a substrate for a flexible device such as a flexible display, that is, a low linear expansion coefficient and high transparency in the visible light region (high light transmittance, low yellowness). The laser lift-off method can be suitably used when peeling the substrate from the carrier base material because it exhibits low retardation, is excellent in flexibility, and particularly can sufficiently absorb light having a specific wavelength (308 nm).
Such a present invention is a substrate for a flexile device that requires characteristics such as high flexibility, low linear expansion coefficient, high transparency (high light transmittance, low yellowness), low retardation, particularly in the production process thereof. The laser lift-off method can be adopted, and can sufficiently cope with the progress in the field of flexible device substrates.

Hereinafter, the present invention will be described in detail.
The composition for forming a flexible device substrate of the present invention contains the following specific polyimide, titanium dioxide particles, silicon dioxide particles and an organic solvent, and optionally contains a crosslinking agent and other components.

[Polyimide]
The polyimide used in the present invention is a polyimide having an alicyclic skeleton in the main chain, and preferably includes a tetracarboxylic dianhydride component including an alicyclic tetracarboxylic dianhydride and a fluorine-containing aromatic diamine. It is the polyimide obtained by imidating the polyamic acid obtained by making it react with the diamine component to contain. That is, the polyimide is preferably an imidized product of polyamic acid, and the polyamic acid is a diamine component including a tetracarboxylic dianhydride component including an alicyclic tetracarboxylic dianhydride and a fluorine-containing aromatic diamine. It is a reaction product.
Among them, the alicyclic tetracarboxylic dianhydride includes a tetracarboxylic dianhydride represented by the following formula (C1), and the fluorine-containing aromatic diamine is represented by the following formula (A1). It is preferable that the diamine contains.

〔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。）〕

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

(In the formula, a plurality of R's independently represent a hydrogen atom or a methyl group, 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。）

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

(In the formula, * represents a bond.)

Among the tetracarboxylic dianhydrides represented by the above formula (C1), B ¹ in the formula is represented by the formulas (X-1), (X-4), (X-6), (X-7). Are preferred.
Of the diamines represented by the above formula (A1), compounds in which B ² is represented by the formulas (Y-12) and (Y-13) are preferred.
As a preferred example, a polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride represented by the above formula (C1) and a diamine represented by the above formula (A1) is described below. The monomer unit represented by Formula (2) is included.

In order to obtain a resin thin film having low linear expansion coefficient, low retardation and high transparency, which is the object of the present invention, and excellent in flexibility, and suitable for flexible device substrates, a tetracarboxylic dianhydride component The alicyclic tetracarboxylic dianhydride, for example, the tetracarboxylic dianhydride represented by the above formula (C1) is preferably 90 mol% or more, and 95 mol% or more. More preferably, it is most preferable that all (100 mol%) are tetracarboxylic dianhydrides represented by the above formula (C1).
Similarly, in order to obtain the resin thin film having the above-mentioned low linear expansion coefficient, low retardation and high transparency and excellent flexibility, the fluorine-containing aromatic diamine is used with respect to the total number of moles of the diamine component. For example, the diamine represented by the above formula (A1) is preferably 90 mol% or more, and more preferably 95 mol% or more. Moreover, the diamine represented by the said Formula (A1) may be sufficient as all (100 mol%) of a diamine component.

As an example of a suitable aspect, the polyimide used by this invention contains the monomer unit represented by following formula (2).

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.

The polyimide used by this invention is a diamine containing the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the above-mentioned formula (C1), and the diamine represented by a formula (A1). In addition to the monomer units derived from the components, other monomer units may be included. The content ratio of the other monomer units is arbitrarily determined as long as the properties of the resin thin film suitable as a flexible device substrate formed from the composition of the present invention are not impaired. The ratio is derived from the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the formula (C1) and the diamine component containing the diamine represented by the formula (A1). The total number of moles of monomer units is preferably less than 20 mol%, more preferably less than 10 mol%, and even more preferably less than 5 mol%.

Examples of such other monomer units include, but are not limited to, monomer units 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). In the above formula (3), B represents a divalent organic group, preferably a divalent group represented by any one of formulas (B-1) to (B-11). In each formula, * 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 represents the above formulas (Y-1) to ( Y-34) may be a divalent group. 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 formulas (X-1) to (X It may be a tetravalent group represented by any of -12).
When the monomer unit represented by the formula (3) is contained in the polyimide of the present invention, A and B may contain only a monomer unit composed of only one of the groups exemplified by the following formula, for example. In addition, at least one of A and B may contain two or more monomer units selected from two or more groups exemplified below.

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

Moreover, the polyimide used by this invention contains the diamine represented by the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the above-mentioned formula (C1), and a formula (A1). When the monomer unit derived from the diamine component and other monomer units represented by the above formula (3) are included, the polyimide containing each monomer unit is represented by the above formula (C1) as a tetracarboxylic dianhydride component. ) And a tetracarboxylic dianhydride represented by the following formula (5), a diamine represented by the above formula (A1) as a diamine component, and a formula represented by the following formula (6): The obtained diamine is polymerized in an organic solvent, and the resulting polyamic acid is imidized.

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

Specifically, as the tetracarboxylic dianhydride represented by the formula (5), pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride, 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-tetrafluorodifuro [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 ′] difuran-1,3,5,7-tetraone, N, N ′-[2,2′-bis (trifluoromethyl) biphenyl-4,4′-diyl] bis (1, Aromatic dicarboxylic acids such as 3-dioxo-1,3-dihydroisobenzofuran-5-carboxamide); 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2, 3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-cyclohexanetetra Carboxylic dianhydride, 3,4-dicarboxy-1, Alicyclic tetracarboxylic dianhydrides such as 1,3,4-tetrahydro-1-naphthalene succinic dianhydride; aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride Non-limiting examples include anhydrides.
Among these, tetracarboxylic dianhydrides in which A in the formula (5) is a tetravalent group represented by any one of the above formulas (A-1) to (A-4) are preferable. , 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-tetrafluorodifuro [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 '] difuran-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). ) Benzene-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-pheny Diamine, 2,5-dimethoxy-1,4-phenylenediamine, 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 ′-(perfluoropropane-2,2-diyl) dianiline, 4,4′-oxybis [3- (trifluoromethyl) aniline], 1,4-bis (4-aminophenoxy) Benzene, 1,3′-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, benzidine, 2-methylben Gin, 3-methylbenzidine, 2- (trifluoromethyl) benzidine, 3- (trifluoromethyl) benzidine, 2,2'-dimethylbenzidine (m-tolidine), 3,3'-dimethylbenzidine (o-tolidine) 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-amino Phenyl) -2,3-dihydro-1, , 3-trimethyl-1H-indene-5 (or 6) amine or the like; 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-diaminoadamantane, 2,2-bis ( 4-Aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane, 1,3-propane Diamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, etc. 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 one of the formulas (B-1) to (B-11) are preferable, that is, 2,2 ′. -Bis (trifluoromethoxy)-(1,1'-biphenyl) -4,4'-diamine [other name: 2,2'-dimethoxybenzidine], 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 [Alternative name: Octafluorobenzidine], 2, 3, 5, -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-indene-5 (or 6) amine may be mentioned as a preferred diamine.

From the viewpoint of the mechanical strength of the film to be formed, the content of the polyimide is usually 10% by mass or more, preferably 20% by mass or more, more preferably based on the total solid content of the composition for forming a flexible device substrate. From the viewpoint of the optical properties of the low retardation film (thickness direction retardation (R _th ) and linear expansion coefficient (CTE) do not decrease), it is usually 80% by mass or less, preferably 75% by mass or less. More preferably, it is 70 mass% or less. In addition, solid content means the remaining components remove | excluding a solvent from all the components which comprise the composition for flexible device board | substrate formation.

<Synthesis of polyamic acid>
As described above, the polyimide used in the present invention is represented by the tetracarboxylic dianhydride component including the alicyclic tetracarboxylic dianhydride represented by the above formula (C1) and the above formula (A1). It is obtained by imidizing a polyamic acid obtained by reacting a diamine component containing a fluorine-containing aromatic diamine.
The reaction for obtaining a polyamic acid from the above two components is advantageous in that it can proceed relatively easily in an organic solvent and no by-product is produced.

The charging ratio (molar ratio) between the tetracarboxylic dianhydride component and the diamine component in such a reaction is appropriately set in consideration of the molecular weight of the polyamic acid and the polyimide obtained by subsequent imidization. However, with respect to the diamine component 1, the tetracarboxylic dianhydride component can usually be about 0.8 to 1.2, for example about 0.9 to 1.1, preferably 0.95. About 1.02. Similar to the normal polycondensation reaction, the closer the molar ratio is to 1.0, the higher 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 dissolves. 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, hexamethylsulfoxy Isopropyl alcohol, methoxymethyl pentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, 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 mono Propyl 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, diisobutyl ketone, Methylcyclohexene, propyl ether, dihexyl Ether, 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. You may use these individually or in combination of 2 or more types.
Furthermore, even if the solvent does not dissolve the polyamic acid, it may be used by mixing with the above solvent as long as the produced polyamic acid does not precipitate. In addition, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyamic acid, it is preferable to use a dehydrated and dried organic solvent as much as possible.

As a method of reacting the tetracarboxylic dianhydride component and the diamine component in an organic solvent, for example, 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 stirred here. A method in which the anhydride component is added as it is, or a method in which the component is dispersed or dissolved in an organic solvent, or a solution or solution in which the tetracarboxylic dianhydride component is dispersed or dissolved in an organic solvent. The method of adding a diamine component, the method of adding a tetracarboxylic dianhydride component and a diamine compound component alternately, etc. are mentioned, As long as the target polyamic acid is obtained, it is not limited to these methods.
Moreover, 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, individually individually, or further individually. Low molecular weight substances may be mixed and reacted to form high molecular weight substances.

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

<Imidization of polyamic acid>
Examples of the method for imidizing the polyamic acid include thermal imidization in which the polyamic acid solution is heated as it is, and catalytic imidization in which a catalyst is added to the polyamic acid solution.
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 carry out while removing water generated by the imidation reaction from the system.

The chemical (catalyst) imidization of polyamic acid is carried out by adding a basic catalyst and an acid anhydride to a polyamic acid solution, and igniting the system under a temperature condition of −20 to 250 ° C., preferably 0 to 180 ° C. This 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 amide acid group of the polyamic acid, and the amount of the acid anhydride is 1 to 50 mol of the amide acid group of the polyamic acid. Double, preferably 2 to 30 mole times.

Examples of the basic catalyst include amines such as pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, 1-ethylpiperidine, etc. Among them, pyridine is preferable because it has an appropriate basicity for proceeding with the reaction.
Examples of acid anhydrides include aliphatic carboxylic acid anhydrides such as acetic anhydride, and aromatic carboxylic acid anhydrides such as trimellitic anhydride and pyromellitic anhydride. This is preferable because it can be easily purified.
The imidization rate by catalytic imidation can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

In the polyimide used in the present invention, the dehydration cyclization rate (imidation rate) of the amic acid group is not necessarily 100%, and can be arbitrarily adjusted according to the use and purpose. Particularly preferably, it is 50% or more.

In the present invention, after filtering the reaction solution, the filtrate may be used as it is, or may be diluted or concentrated, and may be combined with titanium dioxide, silicon dioxide, etc., which will be described later, to form a flexible device substrate forming composition. . In this way, when filtration is performed, not only can the contamination of the resin thin film obtained be deteriorated in heat resistance, flexibility, or deterioration of linear expansion coefficient characteristics, but also efficiently obtain a composition for forming a flexible device substrate. Can do.

The polyimide used in the present invention has a weight average molecular weight (Mw) in terms of polystyrene of gel permeation chromatography (GPC) 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 poured into a poor solvent and precipitated. Examples of the poor solvent used for precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, isopropanol, and water. A polymer precipitated in a poor solvent and collected by filtration can be dried at normal temperature or under reduced pressure at room temperature or by heating.
In addition, when the polymer collected by precipitation is re-dissolved in an organic solvent and re-precipitation is collected 2 to 10 times, impurities in the polymer can be reduced. In this case, it is preferable to use three or more kinds of poor solvents such as alcohols, ketones, and hydrocarbons as the poor solvent because the purification efficiency is further increased.

The organic solvent for dissolving the resin component in the reprecipitation collection 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, tetra Methyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate , Propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, and the like. Two or more kinds of these solvents may be mixed and used.

[titanium dioxide]
Titanium dioxide (titania) used in the present invention is not particularly limited, but titanium dioxide in the form of particles, for example, particles having a particle diameter of 3 nm to 200 nm, preferably 3 nm to 50 nm, more preferably 3 nm to 20 nm are preferably used. it can. By using titanium dioxide particles having a particle diameter in such a numerical range, it is possible to perform substrate peeling by the laser lift-off method with higher accuracy and higher reproducibility.
In the present invention, the particle diameter of the titanium dioxide particles is represented as a primary particle diameter obtained by observing titanium dioxide particles in a titanium dioxide sol described later with an electron microscope.
Titanium dioxide may have an anatase type, a rutile type, an anatase / rutile mixed type, or a brookite type crystal structure. Among these, those containing a rutile type are desirable.

In particular, in the present invention, titania-based colloidal particles (colloidal titania) having the above particle diameter values can be suitably used, and titania sol can be used as the colloidal titania.
The titania colloidal particles used in the present invention may be single colloidal particles, a mixture with other high refractive index metal oxides described later, or composite oxide colloidal particles.
The method for producing the titania colloidal particles is not particularly limited, and can be produced by a conventional method, for example, 1) an ion exchange method, 2) a peptization method, or the like.
1) Ion exchange method: A method of treating an acidic salt of titanium with a hydrogen ion exchange resin, or a method of treating a basic salt of titanium with a hydroxyl type anion exchange resin.
2) Peptization: A method in which the gel obtained by neutralizing the acidic salt of titanium with a salt or neutralizing the basic salt of titanium with an acid is washed with an acid or a base ( Japanese Patent Publication No. 4-27168), a method of hydrolyzing an alkoxide of titanium (Japanese Patent Laid-Open No. 2003-176120), or a method of hydrolyzing a basic salt of titanium with heating (Japanese Patent Laid-Open No. 10-245224) ) And the like.
Examples of the other metal oxides include Fe ₂ O ₃ , ZrO ₂ , SnO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , Y ₂ O ₃ , MoO ₃ , WO ₃ , PbO, In ₂ O ₃ , Examples include Bi ₂ O ₃ and SrO, which can be produced in the same manner as the titania colloidal particles. Further examples of composite _{oxides, TiO 2 -SnO 2, TiO 2} -ZrO 2, TiO 2 -ZrO 2 -SnO 2, TiO 2 -ZrO 2 -CeO 2 , and the like, as a method for compounding is For example, methods disclosed in JP 2014-38293 A, JP 2001-122621 A, JP 2000-063119 A, and the like can be employed.

Examples of organic solvents in the above titania 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-pyrrolidone Cyclic ethers such as γ-butyrolactone; glycols such as ethyl cellosolve and ethylene glycol; acetonitrile and the like.
The titania sol has a viscosity of about 0.6 mPa · s to 100 mPa · s at 20 ° C.

Examples of commercially available titania colloidal particles (titania sol) include, for example,
Product name Neutral titania sol TTO-W-5 (Rutile ultrafine titanium oxide aqueous sol, silica surface treatment, manufactured by Ishihara Sangyo Co., Ltd.)
Product name TKS-201 (Anatase type acidic sol, manufactured by Teika Co., Ltd.), Product name KS-202 (Anatase type acidic sol, manufactured by Teika Co., Ltd.), Product name TKS-203 (Anatase type neutral sol, Taker ( )
Product name CSB (anaters type water-based acidic sol, manufactured by Sakai Chemical Industry Co., Ltd.), product name CSB-M (anaters type water-based neutral sol, manufactured by Sakai Chemical Industry Co., Ltd.),
Product name DC-Ti, DCN-Ti, DCB-Ti (above amorphous water-based sol, manufactured by Fuji Titanium Industry Co., Ltd.), organic sol (anatase type, solvent: ethylene glycol, toluene-IPA, Fuji Titanium Industry Co., Ltd.) Made),
Product name QUEEN TITANIC series (aqueous colloid, manufactured by JGC Catalysts & Chemicals Co., Ltd.), trade name OPTALAKE series (non-aqueous colloid, manufactured by JGC Catalysts & Chemicals Co., Ltd.),
Trade name Sun Colloid (registered trademark) HT-R350M7-20 (manufactured by Nissan Chemical Industries, Ltd.)
The titania sol may be produced by dispersing titania particles in an organic solvent according to a conventional method.
Examples of such an organic solvent include the same ones as described above.
Examples of commercially available titania particles include trade name AEROXIDE (registered trademark) TiO ₂ P25 (manufactured by Nippon Aerosil Co., Ltd.).

The content of the titanium dioxide is usually 0.1 mass relative to the total mass of the polyimide, titanium dioxide particles, and silicon dioxide particles in the flexible device substrate-forming composition from the viewpoint of ensuring absorption of light having a wavelength of 308 nm. % Or more, preferably 1% by mass or more, more preferably 2% by mass or more, from the viewpoint of obtaining a thin film excellent in transparency in the visible light region with good reproducibility, usually 30% by mass or less, preferably 25% by mass or less, More preferably, it is 20 mass% or less.
In addition, in the composition for forming a flexible device substrate of the present invention, when the crosslinking agent described later is included, the total amount of the polyimide, titanium dioxide particles, and silicon dioxide particles in the composition for forming a flexible device substrate is used. It is preferable that the titanium content is 3 mass% or more and 16 mass% or less.

[Silicon dioxide]
The silicon dioxide (silica) used in the present invention is not particularly limited, but silicon dioxide in the form of particles, for example, the average particle diameter is 100 nm or less, preferably 5 nm to 100 nm, more preferably 5 nm to 55 nm, and a highly transparent thin film is formed. From the viewpoint of obtaining good reproducibility, the thickness is preferably 5 nm to 50 nm, more preferably 5 nm to 45 nm, still more preferably 5 nm to 35 nm, and still more preferably 5 nm to 30 nm.
In the present invention, the average particle diameter of silicon dioxide particles is an average particle diameter value calculated from specific surface area values measured by a nitrogen adsorption method using silicon dioxide particles.

In particular, in the present invention, colloidal silica having the above average particle size can be suitably used, and silica sol can be used as the colloidal silica. As the silica sol, there can be used an aqueous silica sol produced by a known method using a sodium silicate aqueous 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.
In addition, alkoxysilanes such as methyl silicate and ethyl silicate are obtained by hydrolysis and condensation in an organic solvent such as alcohol in the presence of a catalyst (for example, an alkali catalyst such as ammonia, an organic amine compound, or sodium hydroxide). Or a silica sol obtained by replacing the silica sol with another organic solvent can be used. This substitution can be performed by a usual method such as a distillation method or an ultrafiltration method.
Among these, the present invention preferably uses an organosilica sol whose dispersion medium is an organic solvent.

Examples of the organic solvent in the above-described 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- Examples include cyclic amides such as pyrrolidone; ethers such as γ-butyrolactone; glycols such as ethyl cellosolve and ethylene glycol, acetonitrile, and the like.
The viscosity of the organosilica sol is about 0.6 mPa · s to 100 mPa · s at 20 ° C.

Examples of commercially available organosilica sols include, for example, trade name MA-ST-S (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MT-ST (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.). ), Trade name MA-ST-UP (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MA-ST-M (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MA-ST- L (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST-S (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST (isopropanol-dispersed silica sol, Nissan Chemical Industries, Ltd.) Product name) IPA-ST-UP (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industries Ltd.), product name IPA-ST- (Isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST-ZL (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name NPC-ST-30 (n-propyl cellosolve-dispersed silica sol, NISSAN CHEMICAL INDUSTRY CO., LTD.), Trade name PGM-ST (1-methoxy-2-propanol dispersed silica sol, NISSAN CHEMICAL INDUSTRY CO., LTD.), Trade name DMAC-ST (dimethylacetamide dispersed silica sol, NISSAN CHEMICAL INDUSTRY CO., LTD. Product name XBA-ST (xylene / n-butanol mixed solvent dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), product name EAC-ST (ethyl acetate dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), product Name PMA-ST (propylene glycol monomethyl ether acetate dispersed silica sol, Nissan Chemical Industries, Ltd.) ), Trade name MEK-ST (methyl ethyl ketone dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MEK-ST-UP (methyl ethyl ketone dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MEK-ST-L ( Examples thereof include, but are not limited to, methyl ethyl ketone-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd., and trade name MIBK-ST (methyl isobutyl ketone-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.).
In the present invention, silicon dioxide, for example, silicon dioxide as mentioned in the above product used as organosilica sol, may be used by mixing two or more kinds.

From the viewpoint of obtaining a thin film with low retardation and low linear expansion coefficient with good reproducibility, the content of silicon dioxide is based on the total mass of polyimide, titanium dioxide particles, and silicon dioxide particles in the composition for forming a flexible device substrate. Usually 20% by mass or more, preferably 30% by mass or more, more preferably 40% by mass or more. From the viewpoint of the mechanical strength of the membrane, it is usually 80% by mass or less, preferably 75% by mass or less, more preferably 70% by mass. It is as follows.

[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 hydrogen atoms, carbon atoms, nitrogen atoms and oxygen atoms. And a crosslinking agent comprising 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, it is possible to realize a composition for forming a flexible device substrate that not only provides excellent solvent resistance but also provides a resin thin film suitable for a flexible device substrate with good reproducibility, as well as improved storage stability. can do.
Among these, the total number of hydroxy groups, epoxy groups and alkoxy groups having 1 to 5 carbon atoms per compound in the crosslinking agent is preferably 3 or more from the viewpoint of realizing the solvent resistance of the resulting resin thin film with good reproducibility. From the viewpoint of realizing the flexibility of the resulting 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 possessed by the crosslinking agent include aryl rings such as benzene, nitrogen-containing heteroaryl rings such as pyridine, pyrazine, pyrimidine, pyridazine, 1,3,5-triazine, cyclopentane, cyclohexane, cycloheptane, etc. And cyclic amines such as cycloalkane ring, piperidine, piperazine, hexahydropyrimidine, hexahydropyridazine, hexahydro-1,3,5-triazine and the like.

The number of ring structures per compound in the crosslinking agent is not particularly limited as long as it is 1 or more. However, from the viewpoint of obtaining a resin thin film having high flatness by ensuring the solubility of the crosslinking agent in a solvent, 1 or 2 is 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, a propane-2,2-diyl group, etc. The ring structures may be bonded to each other through a linking group such as a diyl group.

The molecular weight of the crosslinking agent is not particularly limited as long as it has crosslinking ability and dissolves in the solvent to be used, but the solvent resistance of the resulting resin thin film, the solubility of the crosslinking agent itself in an organic solvent, and easy availability In consideration of properties, price, etc., it is preferably about 100 to 500, more preferably about 150 to 400.

The crosslinking 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 or an ester group (bond).

Preferable examples of the crosslinking agent include compounds represented by the formulas selected from the group consisting of the following formulas (K1) to (K5). As one preferred embodiment of formula (K4), formula (K4- As one of the preferred embodiments of the compound represented by 1), the compound represented by the formula (5-1) is exemplified.

In the above formula, each 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, 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 each other hydroxy group, epoxy group (oxa-cyclopropyl group), methoxy group, ethoxy group, 1-propyloxy group, isopropyloxy group, 1-butyloxy group, t-butyloxy group, etc. An alkoxy group having 1 to 5 carbon atoms is represented.
Among these, 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) in consideration of the availability, price, etc. of the crosslinking agent. An alkoxy group is preferable, and a hydroxy group is preferable in the formula (K4).

In the formula (K4), each n represents 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, more preferably 3.

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

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

A commercial item may be used for a crosslinking agent, and what was synthesize | combined with the well-known synthesis | combining method may be used for it.
Commercially available products include CYMEL (registered trademark) 300, 301, 303LF, 303ULF, 304, 350, 3745, XW3106, MM-100, 323, 325, 327, 328, Same 385, Same 370, Same 373, Same 380, Same 1116, Same 1130, Same 1133, Same 1141, Same 1161, Same 1168, Same 3020, Same 202, Same 203, Same 1156, Same MB-94, Same MB- 96, MB-98, 247-10, 651, 658, 683, 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, the same -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 Allnex); TEPIC (registered trademark) V, S, HP, etc. L, PAS, VL, UC (manufactured by Nissan Chemical Industries, Ltd.), TM-BIP-A (manufactured by Asahi Organic Materials Co., Ltd.), 1,3,4,6-tetrakis (methoxymethyl) ) Glycoluril (hereinafter abbreviated as TMG) (Tokyo Chemical Industry Co., Ltd.) 4,4'-methylenebis (N, N-diglycidylaniline) (Aldrich), HP-4032D, HP-7200L, HP-7200, HP-7200H, HP-7200HH, HP-7200HHH, HP- 4700, HP-4770, HP-5000, HP-6000, HP-4710, EXA-4850-150, EXA-4850-1000, EXA-4816, HP-820 (DIC Corporation), TG-G (Shikoku Chemicals) Kogyo Co., Ltd.).

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

Since the amount of the crosslinking agent is appropriately determined according to the type of the crosslinking agent, etc., it cannot be specified unconditionally. However, the total amount of the polyimide, the titanium dioxide, and the silicon dioxide is usually the amount of the resin thin film obtained. From the viewpoint of ensuring flexibility and suppressing embrittlement, it is 50% by mass or less, preferably 100% by mass or less, and from the viewpoint of ensuring solvent resistance of the resulting resin thin film, 0.1% by mass or more, preferably 1% by mass or more.

[Organic solvent]
The composition for forming a flexible device substrate of the present invention contains an organic solvent in addition to the polyimide, titanium dioxide, silicon dioxide and, optionally, a crosslinking agent. This organic solvent is not specifically limited, For example, the thing similar to the specific example of the reaction solvent used at the time of preparation of the said polyamic acid and a polyimide is mentioned. More specifically, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone, γ- Examples include butyrolactone. In addition, an organic solvent may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and γ-butyrolactone are preferable in view of obtaining a resin film having high flatness with good reproducibility.

[Composition for forming flexible device substrate]
The present invention is a composition for forming a flexible device substrate containing the polyimide, titanium dioxide, silicon dioxide, an organic solvent, and optionally a crosslinking agent. Here, the composition for forming a flexible device substrate of the present invention is uniform and phase separation is not observed.
In the composition for forming a flexible device substrate of the present invention, the mixing ratio of the polyimide and the silicon dioxide is preferably polyimide: silicon dioxide = 10: 1 to 1:10, more preferably 8: 2 to 2: 8, for example 7: 3 to 3: 7.
Further, 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, preferably 5% by mass or more and 20% by mass from the viewpoint of film uniformity. It is as follows. In addition, solid content means the remaining components remove | excluding a solvent from all the components which comprise the composition for flexible device board | substrate formation.
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 to the processing characteristics and various functionalities, various other organic or inorganic low-molecular or high-molecular compounds may be blended with the composition for forming a flexible device substrate of the present invention. For example, a catalyst, an antifoaming agent, a leveling agent, a surfactant, a dye, a plasticizer, fine particles, a coupling agent, a sensitizer, and the like can be used. For example, the catalyst may be added for the purpose of reducing the retardation and linear expansion coefficient of the resin thin film.
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, titanium dioxide and silicon dioxide, and optionally a crosslinking agent in the above-mentioned organic solvent. Titanium dioxide, silicon dioxide, and a crosslinking agent as required may be added to the subsequent reaction solution, and the organic solvent may be further added as desired.

[Flexible device substrate]
The organic solvent is removed by applying the composition for forming a flexible device substrate of the present invention described above to a substrate, drying and heating, high heat resistance, high transparency, moderate flexibility, and moderate A resin thin film having a linear expansion coefficient and having a small retardation and selectively absorbing light having a wavelength of 308 nm, that is, a flexible device substrate can be obtained.
And the flexible device substrate, that is, the flexible device comprising the polyimide, the titanium dioxide, silicon dioxide, and optionally a crosslinking agent, that is, the flexible device comprising the cured product of the flexible device substrate forming composition of the present invention. Substrates are also the subject of the present invention.

As a base material used for manufacturing a flexible device substrate (resin thin film), for example, plastic (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetylcellulose, ABS, AS, norbornene resin, etc.), metal , Stainless steel (SUS), wood, paper, glass, silicon wafer, 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 that it is glass. In addition, as a linear expansion coefficient of the base material to apply, from a viewpoint of the curvature of the base material after coating, Preferably it is 40 ppm / degrees C or less, More preferably, it is 30 ppm / degrees C or less.

The method for applying the composition for forming a flexible device substrate on the base material is not particularly limited, and examples thereof include 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, ink jet method, printing method (letter plate, intaglio plate, planographic plate, screen printing, etc.) and the like, and these can be appropriately used according to the purpose.

The heating temperature is preferably 300 ° C. or lower. If the temperature exceeds 300 ° C., the resulting resin thin film becomes brittle, and a resin thin film particularly suitable for display substrate use may not be obtained.
Also, considering the heat resistance and linear expansion coefficient characteristics of the resulting resin thin film, after heating the applied flexible device substrate forming composition at 40 ° C. to 100 ° C. for 5 minutes to 2 hours, the heating temperature is gradually increased as it is. It is desirable to raise the temperature and finally heat at over 175 ° C. to 280 ° C. for 30 minutes to 2 hours. Thus, by heating at a temperature of two or more stages of drying the solvent and promoting molecular orientation, the low thermal expansion characteristics can be expressed with higher 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 at a temperature exceeding 100 ° C. to 175 ° C. for 5 minutes to 2 hours, and then at a temperature exceeding 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, and may be under normal pressure or under reduced pressure, and different pressures are applied at each stage of heating. May be.

The thickness of the resin thin film is appropriately determined in consideration of the type of the flexible device within a range of about 1 to 200 μm, but usually 1 to 60 μm when it is assumed to be used as a substrate for a flexible display. The thickness is about 5 to 50 μm, and the thickness of the coating before heating is adjusted to form a resin thin film having a desired thickness.
The method for peeling the resin thin film formed in this way from the substrate is not particularly limited, and the resin thin film is cooled together with the substrate, and a thin film is cut and peeled or tension is applied via a roll. And a method of peeling off.
In particular, in the present invention, a laser lift-off (LLO) method can be adopted as a method for peeling a resin thin film from a substrate. That is, by irradiating the base material with a light beam having a wavelength of 308 nm from the surface opposite to the surface on which the resin thin film of the base material is formed, the light beam with the wavelength passes through the base material (for example, a glass carrier). The resin thin film can be peeled off from the base material by absorbing this light only in the vicinity of the polyimide and evaporating the polyimide in the portion.
The laser beam 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. Specifically, the oscillation wavelength is ArF (193 nm), KrF (248 nm), XeCl (308 nm). ) And XeF (353 nm), and XeCl (308 nm) is particularly preferable.
As the energy density of the irradiated laser beam, typically, include a range of less than 650 mJ / cm ^2, for instance, the range of 500 mJ / cm ² to 530mJ / cm ^2, the range of 500 mJ / cm ² to 515mJ / cm ² Etc.

The resin thin film according to a preferred embodiment of the present invention thus obtained can achieve high transparency with a light transmittance of 85% or more at a wavelength of 550 nm. On the other hand, the light transmittance at a wavelength of 308 nm is 5% or less, that is, it is possible to achieve sufficient light absorption at the wavelength that enables the resin thin film to be peeled from the substrate to which the laser lift-off method is applied.
Further, the resin thin film can have a low coefficient of linear expansion coefficient of, for example, 40 ppm / ° C. or less, particularly 10 ppm / ° C. to 35 ppm / ° C. at 30 ° C. to 220 ° C., and has excellent dimensional stability during heating. It is.
Further, the resin thin film has an in-plane retardation R ₀ represented by the product of birefringence (difference between two in-plane orthogonal refractive indexes) and a film thickness when the wavelength of incident light is 590 nm, As an average value of two phase differences obtained by multiplying two birefringences (differences between two in-plane refractive indices and a refractive index in the thickness direction) when viewed from the cross section in the vertical direction, respectively, by the film thickness thickness direction retardation R _th represented are both featuring a very small. When the average film thickness is about 15 μm to 40 μm, the resin thin film has a thickness direction retardation R _th of less than 700 nm, for example, 450 nm or less, for example, 1 nm to 410 nm, and in-plane retardation R ₀ is less than 4.5. For example, 0.1 to 4.2, and the birefringence Δn has a very low value of less than 0.015, for example, 0.0028 to 0.0144.

Since the resin thin film described above has the above-mentioned characteristics, it satisfies the conditions necessary for a base film of a flexible device substrate, and is particularly preferably used as a base film for a substrate of a flexible device, particularly a flexible display. it can.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, the abbreviation of the used reagent, the used apparatus, and its conditions are as follows.

<Measurement of number average molecular weight (Mn) and weight average molecular weight (Mw)>
Apparatus: Showdex GPC-101, Showa Denko Co., Ltd.
Column: KD803 and KD805
Column temperature: 50 ° C
Elution solvent: DMF, flow rate: 1.5 ml / min calibration curve: standard polystyrene

<Acid dianhydride>
CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride BODAxx: bicyclo [2,2,2] octane-2,3,5,6-tetracarboxylic dianhydride <diamine>
TFMB: 2,2′-bis (trifluoromethyl) benzidine <organic solvent>
NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone

[Synthesis Example of Polyimide (I) (Preparation Example of Polyimide Solution (PI))]
Add 11.208 g (0.035 mol) of TFMB and 66.56 g of γ-butyrolactone (GBL) to a three-necked reaction flask with a nitrogen inlet / outlet and equipped with a Dean-Stark device and mechanical stirrer, and start stirring. The temperature was raised to 90 ° C. After the diamine (TFMB) was completely dissolved in the solvent, 4.376 g (0.0175 mol) of BODAxx and 14.26 g of GBL were added and heated at 140 ° C. for 10 minutes in a nitrogen atmosphere. Thereafter, 3.432 g (0.0175 mol) of CBDA and 14.26 g of GBL (γ-butyrolactone) were added and reacted for 10 minutes in a nitrogen atmosphere. 0.152 g of 1-ethylpiperidine was added to the reaction, the temperature was raised to 180 ° C. and held for 7 hours. GBL 86.02g was added to the reaction mixture, and it diluted so that solid content concentration (concentration of the component except an organic solvent) might be 10.5 mass%, and the target polyimide solution (PI) was obtained (polyimide). Molecular weight of (I): Mw = 169,385, Mn = 54,760).

[Preparation example of titania sol (TiO ₂ -GBL)]
In a 1000 mL round bottom flask, methanol-dispersed titania sol manufactured by Nissan Chemical Industries, Ltd .: TiO ₂ -MeOH (“Sun Colloid (registered trademark) HT-R305M7-20”, rutile type, solid content of titania: 30.6% by mass ) 91.13 g and γ-butyrolactone 82.02 g. Then, the flask was connected to a vacuum evaporator to reduce the pressure in the flask, and immersed in a warm water bath at about 35 ° C. for 60 minutes, so that titania sol (TiO ₂ -GBL) in which the solvent was replaced with γ-butyllactone was about 107 0.0 g was obtained (titania solid content concentration: 26.06% by mass).
In the titania sol, the primary particle diameter of titanium dioxide particles observed with an electron microscope was 10 to 12 nm.

[Preparation Example of Silica Sol (GBL-M)]
A 1000 mL round bottom flask was charged with 350 g of methanol-dispersed silica sol: MA-ST-M (silica solid content concentration: 40.4 mass%) manufactured by Nissan Chemical Industries, Ltd. and 419 g of γ-butyllactone. Then, the flask was connected to a vacuum evaporator to reduce the pressure in the flask, and immersed in a warm water bath at about 35 ° C. for 20 to 50 minutes, so that silica sol (GBL-M) in which the solvent was substituted from methanol to γ-butyllactone was about 560.3 g was obtained (silica solid content concentration: 25.25% by mass).
In the silica sol, the average particle diameter calculated from the specific surface area value measured by the nitrogen adsorption method was 22 nm. Specifically, the specific surface area of the dry powder of silica sol was measured using a specific surface area measuring device Monosorb MS-16 manufactured by Yuasa Ionics Co., Ltd., and the measured specific surface area S (m ² / g) was used as D. The average primary particle diameter was calculated by the formula (nm) = 2720 / S.

[Preparation of composition for forming flexible device substrate]
[Example 1]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 9703g and GBL 0.946g were added, and it stirred for 30 minutes, and obtained the composition for flexible device board | substrate formation.
[Example 2]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 8316 g, TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) 0.1343 g and GBL 0.95 g were added and stirred for 30 minutes to obtain a composition for forming a flexible device substrate.
[Example 3]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 5718 g, TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) 0.0503 g and GBL 0.5654 g were added and stirred for 30 minutes to obtain a composition for forming a flexible device substrate.
[Example 4]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 5925 g, TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) 0.0302 g and GBL 0.5648 g were added and stirred for 30 minutes to obtain a composition for forming a flexible device substrate.
[Example 5]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 6133 g, 0.0100 g of TiO ₂ -GBL titania sol (titania solid content concentration: 26.06% by mass) and 0.5642 g of GBL were added and stirred for 30 minutes to obtain a composition for forming a flexible device substrate.
[Example 6]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 6186 g, 0.0050 g of TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) and 0.5640 g of GBL were added and stirred for 30 minutes to obtain a composition for forming a flexible device substrate.
[Example 7]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 37425 g, TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) 0.04029 g and GBL 0.335 g were added and stirred for 30 minutes to obtain a composition for forming a flexible device substrate.

[Example 8]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 5718 g, TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) 0.05 g, GBL 1.264 g were added, and TEPIC-L (purity 99%) 0.029 g was added, and the mixture was stirred for 30 minutes. Then, a composition for forming a flexible device substrate was obtained.
[Example 9]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 5198 g, TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) 0.1 g and GBL 1.266 g were added, and TEPIC-L (purity 99%) 0.029 g was further added, followed by stirring for 30 minutes. Then, a composition for forming a flexible device substrate was obtained.
[Example 10]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 4678 g, TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) 0.1511 g and GBL 1.268 g were added, and TEPIC-L (purity 99%) 0.029 g was added, and the mixture was stirred for 30 minutes. Then, a composition for forming a flexible device substrate was obtained.
[Example 11]
At room temperature, 1 g of the polyimide solution prepared in the synthesis example (PI, polyimide solid content concentration: 10.5 mass%) was added to the GBL-M silica sol prepared in the preparation example (silica solid content concentration: 25.25 mass%). 5458 g, TiO ₂ -GBL titania sol (titania solid content concentration: 26.06 mass%) 0.0755 g, and GBL 0.5654 g were added and stirred for 30 minutes to obtain a composition for forming a flexible device substrate.

[Creation of resin thin film]
Each of the flexible device substrate forming compositions obtained in Examples 1 to 10 was applied to a glass substrate, and the coating film was applied at 50 ° C. for 30 minutes, 140 ° C. for 30 minutes, 200 ° C. for 60 minutes in the atmosphere, and then A resin thin film was obtained by sequentially heating at 280 ° C. for 60 minutes under a vacuum of −99 kpa.
The obtained thin film was peeled off by mechanical cutting and subjected to subsequent evaluation.

[Evaluation of thin film]
Heat resistance and optical characteristics of each resin thin film (evaluation sample) prepared by the above procedure, that is, linear expansion coefficient (CTE) at 30 ° C. to 220 ° C., 5% weight loss temperature (Td _5% ), light transmittance (T _{308 nm} , T _{550 nm} ) and CIE b ^* values (yellow evaluation), retardation (R _th , R ₀ ) and birefringence (Δn) were evaluated according to the following procedures. The results are shown in Table 1.
1) Linear expansion coefficient (CTE)
Using TMA Q400 manufactured by TA Instruments, the thin film was cut into a size of 5 mm wide and 16 mm long, first heated at 10 ° C./min and heated to 50 to 300 ° C. (first heating), then 10 ° C. The linear expansion at 30 ° C. to 220 ° C. of the second heating when the temperature is lowered to 50 ° C./min and cooled to 50 ° C. and then heated to 10 ° C./min and heated to 30 ° C. to 420 ° C. (second heating) It calculated | required by measuring the value of a coefficient (CTE [ppm / degrees C]). Note that a load of 0.05 N was applied through the first heating, cooling, and second heating.
2) 5% weight loss temperature (Td _5% )
5% weight loss temperature (Td _5% [° C.]) is measured by using a TGA Q500 manufactured by TA Instruments Inc. and raising the temperature of about 5 to 10 mg of thin film from nitrogen to 50 to 800 ° C. at a rate of 10 ° C./min. I asked for it.
3) CIE b value (CIE b ^* )
The CIE b value (CIE b ^* ) was measured using a SA4000 spectrometer manufactured by Nippon Denshoku Industries Co., Ltd., at room temperature, using air as a reference.
4) Light transmittance (transparency) (T _308nm , T _550nm )
Light transmittance at wavelengths of 308 nm and 550 nm (T _{308 nm} , T _{550 nm} [%]) was measured using UV-3600 manufactured by Shimadzu Corporation at room temperature and with reference as air.
5) Retardation (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 Scientific Instruments.
The thickness direction retardation (R _th ) and the in-plane retardation (R ₀ ) are calculated by the following equations.
R ₀ = (Nx−Ny) × d = ΔNxy × d
R _th = [(Nx + Ny) / 2−Nz] × d = [(ΔNxz × d) + (ΔNyz × d) / 2
Nx, Ny: Two in-plane orthogonal refractive indexes (Nx> Ny, Nx is also called the slow axis, and Ny is also called the fast axis)
Nz: Refractive index in the thickness (perpendicular) direction (perpendicular) to the surface d: Film thickness ΔNxy: Difference between two in-plane refractive indices (Nx−Ny) (birefringence)
ΔNxz: difference between in-plane refractive index Nx and thickness direction refractive index Nz (birefringence)
ΔNyz: difference between in-plane refractive index Ny and thickness direction refractive index Nz (birefringence)
6) Film thickness (d)
The film thickness of the obtained thin film was measured with a thickness gauge manufactured by Teclock Co., Ltd.
7) Birefringence (Δn)
Using the thickness direction retardation (R _th ) obtained by the above-mentioned <5) Retardation>, the following formula was used.
ΔN = [R _th / d (film thickness)] / 1000

[Solvent resistance test]
At room temperature, the composition for forming a flexible device substrate obtained in Examples 1 and 3 to 10 was applied onto a glass substrate, and the coating film was baked. A few drops of Oka Kogyo Co., Ltd. were dropped and then heated in an atmospheric oven at 60 ° C. for 3 minutes. Thereafter, TOK-106 was wiped off, and the appearance of the thin film was visually confirmed.
The appearance of the thin film before and after the test was visually observed and evaluated according to the following criteria.
○: After the solvent test, the thin film does not shrink or expand. Δ: After the solvent test, the thin film slightly contracts or expands. X: After the solvent test, the thin film dissolves, or contracts or expands.

[Flexibility evaluation]
When the obtained thin film was held with both hands and bent at an acute angle (about 30 degrees), it was evaluated as ◯ when it did not crack and x when cracked.

Table 1 shows the results of optical characteristics of the resin thin films obtained from the respective flexible device substrate forming compositions, and Table 2 shows the results of heat resistance and solvent resistance tests.

As shown in Table 1, the resin thin films obtained from the flexible device substrate forming compositions of Examples 2 to 11 have a high light transmittance [%] at a wavelength of 550 nm, while the light transmittance at a wavelength of 308 nm is 5%. The results suggesting that the laser lift-off method can be applied. The resin thin film also has a low yellowness (CIE b ^* ), a thickness direction retardation R _th of 404 nm or less, an in-plane retardation R ₀ of 4.2 nm or less, and a birefringence Δn of less than 0.015. The value was extremely low. As shown in Table 2, the resin thin film had a low coefficient of linear expansion [ppm / ° C.] (30 to 220 ° C.) (less than 31 ppm / ° C.), improved heat resistance, and flexibility. . Furthermore, in Example 8 thru | or Example 10, the result of having solvent tolerance with respect to a solvent was obtained.
On the other hand, the resin thin film of Example 1 had the same heat resistance and optical characteristics as those of Examples 2 to 11, but had a high light transmittance of 66.5% at a wavelength of 308 nm. This result suggests that it is difficult to apply the laser lift-off method in the exfoliation.

[Removal of resin thin film by LLO method]
The composition for forming a flexible device substrate obtained in Examples 1 and 11 was applied to a glass substrate, and the coating film was applied at 50 ° C. for 30 minutes, 140 ° C. for 30 minutes, 200 ° C. for 60 minutes in the atmosphere, and then − A resin thin film was obtained by sequentially heating at 280 ° C. for 60 minutes under a vacuum of 99 kpa.
It was evaluated whether or not the resin thin film prepared above was peeled off by the LLO method.
The following conditions were adopted as the LLO method.
Laser light source: Maxima laser XeCl (308 nm)
Energy ^{Density: 420mJ / cm 2, 500mJ /} cm 2, 515mJ / cm 2, 530mJ / cm 2, 560mJ / cm 2, 630mJ / cm 2
Stage moving speed: 7.8 mm / sec Laser beam size: 14 mm × 1.3 mm (maximum energy size: 7.8 mm × 1.3 mm), laser beam overlapping scanning range is 80%
The results are shown in Table 3.
In the table, ◯ represents that the resin thin film was peeled off, Δ represents that there was a partial defect, and × represents that no peeling occurred.

As shown in Table 3, it was confirmed that the resin thin film of the present invention shown in Example 11 can be peeled off by the LLO method. On the other hand, the resin thin film of Example 1 containing no TiO ₂ was not peeled off under the same conditions.

Thus, the composition for forming a flexible device substrate of the present invention has characteristics such as a low linear expansion coefficient, high transparency (high light transmittance, low yellowness), low retardation, and excellent solvent resistance. That is, it is a material that can form a resin thin film that satisfies the requirements as a base film of a flexible device substrate. In particular, since the resin thin film sufficiently absorbs light of a specific wavelength (308 nm) and can be applied with a laser lift-off method, it is particularly preferably used as a base film of a flexible device substrate for mass production of flexible devices. I can expect to be able to.

Claims (12)

A polyimide having an alicyclic skeleton in the main chain;
Titanium dioxide particles having a particle diameter of 3 nm to 200 nm,
The composition for flexible device board | substrate formation containing the silicon dioxide particle whose average particle diameter computed from the specific surface area value measured by the nitrogen adsorption method is 100 nm or less, and the organic solvent. The said titanium dioxide particle is an amount of 0.1 mass% or more and 20 mass% or less for flexible device board | substrate formation with respect to the total mass of the said polyimide, the said titanium dioxide particle, and the said silicon dioxide particle. Composition. Furthermore, it is a compound composed only of a hydrogen atom, a carbon atom, a nitrogen atom and an oxygen atom, and has 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 a crosslinking agent comprising a compound having a cyclic structure,
The composition for forming a flexible device substrate according to claim 1. The composition for forming a flexible device substrate according to claim 3, wherein the titanium dioxide particles are in an amount of 3% by mass to 16% by mass with respect to a total mass of the polyimide, the titanium dioxide particles, and the silicon dioxide particles. . The polyimide is a polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a diamine component containing a fluorinated aromatic diamine. The composition for forming a flexible device substrate according to any one of claims 1 to 4. The composition for forming a flexible device substrate according to claim 5, wherein the alicyclic tetracarboxylic dianhydride includes a tetracarboxylic dianhydride represented by the formula (C1).

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

(In the formula, a plurality of R's independently represent a hydrogen atom or a methyl group, and * represents a bond.) The composition for forming a flexible device substrate according to claim 5 or 6, wherein the fluorine-containing aromatic diamine contains a diamine represented by the formula (A1).

(Wherein 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 composition for forming a flexible device substrate according to any one of claims 1 to 7, wherein a 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 any one of claims 1 to 8, wherein an average particle size of the silicon dioxide particles is 60 nm or less. The composition for forming a flexible device substrate according to any one of claims 1 to 9, which is a substrate forming composition for a flexible device to which a laser lift-off method is applied. The flexible device board | substrate formed from the composition for flexible device board | substrate formation as described in any one of Claims 1 thru | or 10. The process for apply | coating the composition for flexible device board | substrate formation as described in any one of Claims 1 thru | or 10 to a base material, drying and heating, and forming a flexible device board | substrate,
The manufacturing method of a flexible device board | substrate including the peeling process which peels the said flexible device board | substrate from the said base material by the laser lift-off method.