TWI775739B - Composition for forming flexible device substrate - Google Patents

Abstract

An object of the present invention is to provide a resin film that is also excellent in heat resistance and has a low retardation, especially a resin film suitable for use as a substrate of a flexible element, and a specific absorption that can be applied to a laser lift-off method. A composition for forming a flexible element substrate of a resin film for wavelength light is intended.

The solution of the present invention is a composition for forming a flexible element substrate and a resin film formed from the composition for forming a flexible element substrate, the composition for forming a flexible element substrate comprising: a polyamide Amines, titanium dioxide particles with a particle diameter of 3 nm to 200 nm, silicon dioxide particles with an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method, and an organic solvent.

Description

Composition for forming flexible element substrate

The present invention relates to a composition for forming a flexible element substrate, and more specifically, in a step of peeling a substrate from a carrier base material, using a laser lift-off method, which can be suitably used in flexible displays and the like. A composition for the formation of flexible device substrates.

In recent years, along with the rapid progress of electronics such as liquid crystal displays and organic electroluminescence displays, thinning and weight reduction of elements have been required, and further flexibility has been required.

Among these components, various electronic components, such as thin film transistors or transparent electrodes, are formed on glass substrates. However, by replacing the glass material with a soft and lightweight resin material, the components themselves can be Thinning or lightweight, flexible.

Under such circumstances, polyimide is attracting attention as a substitute material for glass. In addition, the polyimide suitable for this purpose is required to have the same transparency as glass in many cases, not only flexibility. In order to realize these properties, it is reported that the use of alicyclic diamine components or alicyclic anhydride components as raw materials The obtained semi-alicyclic polyimide or fully alicyclic polyimide (for example, refer to Patent Documents 1 to 3).

On the other hand, in the manufacture of flexible displays, it has been reported that the laser lift-off method (LLO method), which has been used in the manufacture of high-brightness LEDs and three-dimensional semiconductor packages, etc., can be properly peeled off from the glass carrier. object substrate (for example, Non-Patent Document 1).

In the manufacture of flexible displays, a polymer substrate made of polyimide, etc. is placed on a glass carrier, and then a circuit including electrodes, etc., is formed on the substrate. Finally, the substrate must be removed from the substrate together with the circuit and the like. The glass carrier is peeled off. In this peeling step, the LLO method is used, that is, when light with a wavelength of 308 nm is irradiated on the glass carrier from the side opposite to the side on which the circuit or the like is formed, the light with the wavelength passes through the glass carrier, and only the polymer ( Polyimide) absorbs this light and evaporates (sublimates). As a result, it has been reported that the performance of the display can be determined, and the circuit and the like provided on the substrate can be selectively peeled off from the glass carrier without affecting the substrate.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2013-147599

[Patent Document 2] Japanese Patent Laid-Open No. 2014-114429

[Patent Document 3] International Publication No. 2015/152178

[Non-patent literature]

[Non-Patent Document 1] Journal of Information Display, 2014, Vol 15, No.1, p.p.1-4

The LLO method is more likely to be used as a highly advantageous substrate lift-off method in the manufacture of flexible displays for the above-mentioned process superiority. In addition, with the practical application of flexible displays, the reality of mass production is increased, and the requirements for polymer substrates for flexible displays to which the LLO method can be applied are also increased.

In the manufacture of flexible displays, in order to enable the adoption of the LLO method, polymer substrates are sought to absorb light of specific wavelengths. However, semi-alicyclic polyimide or fully alicyclic polyimide, which has been proposed as a substrate material for flexible displays so far, contains an alicyclic moiety, suppresses the absorption of light in the visible light region, and is transparent. The reverse side with excellent properties also suppresses the absorption of light in the ultraviolet region, and in many cases, the light in the ultraviolet region (eg, 308 nm) cannot be sufficiently absorbed to make the LLO method applicable.

Due to such a trade-off relationship, there are many cases where the LLO method cannot be applied to an existing material including a semi-alicyclic polyimide or a fully alicyclic polyimide. Therefore, in the field of flexible displays, a substrate material is being sought that suppresses absorption in the visible light region, has excellent transparency, and has the characteristics of sufficiently absorbing light of a specific wavelength (eg, 308 nm) that can be applied to the LLO method.

The present invention has been made in view of such matters, and is intended to provide A composition for forming a flexible element substrate that provides a resin film with excellent performance as a base film of a flexible element substrate such as a flexible display substrate, which is not only excellent in heat resistance and flexibility, but also has low retardation characteristics, In particular, in addition to ensuring transparency in the visible light region, the purpose is to form a composition for forming a flexible element substrate that can sufficiently absorb light of a specific wavelength (308 nm) for which laser lift-off is applicable.

The inventors of the present invention, as a result of diligent research in order to achieve the above object, found that a resin film comprising titanium dioxide particles and silicon dioxide particles blended with a polyimide having an alicyclic skeleton in its main chain also has excellent heat resistance and a relatively low retardation. low, and furthermore excellent flexibility, and by setting the blending amount of the silica within a predetermined range, a resin film with excellent heat resistance, low retardation, excellent flexibility, and excellent transparency can be realized, In particular, by blending the titanium dioxide particles in a specific amount, a resin film that can fully absorb the light of a specific wavelength that can be applied to the LLO method while ensuring the aforementioned transparency can be realized, and can be suitably used in flexible displays and other applications. The substrate of the flexible element completes the present invention.

That is, the present invention, as a first aspect, relates to a composition for forming a flexible element substrate comprising: a polyimide having an alicyclic skeleton in its main chain, and titanium dioxide particles having a particle diameter of 3 nm to 200 nm. , silica particles with an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen sorption method, and Organic solvents.

As a second aspect, the composition for forming a flexible element substrate according to the first aspect, wherein the titanium dioxide particles are 0.1 mass relative to the total mass of the polyimide, the titanium dioxide particles, and the silicon dioxide particles. % or more and 20 mass % or less.

As a third viewpoint, the composition for forming a flexible element substrate according to the first viewpoint further includes a crosslinking agent, and the crosslinking agent is composed of a compound consisting of only hydrogen atoms and carbon atoms. , a nitrogen atom and an oxygen atom, and has two or more groups selected from the group consisting of a hydroxyl group, an epoxy group, and an alkoxy group having 1 to 5 carbon atoms, and has a cyclic structure.

As a fourth aspect, the composition for forming a flexible element substrate according to the third aspect, wherein the titanium dioxide particles are 3 mass relative to the total mass of the polyimide, the titanium dioxide particles, and the silicon dioxide particles. % or more and 16 mass % or less.

As a fifth viewpoint, the composition for forming a flexible element substrate according to any one of the first viewpoint to the fourth viewpoint, wherein the polyimide is made to contain alicyclic tetracarboxylic dianhydride-four A polyimide obtained by imidizing a polyamic acid obtained by reacting a carboxylic dianhydride component with a diamine component containing a fluorine-containing aromatic diamine.

As a 6th viewpoint, it is about the composition for flexible element board|substrate formation as a 5th viewpoint in which the said alicyclic tetracarboxylic dianhydride system contains the tetracarboxylic dianhydride represented by Formula (C1).

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

(in the formula, a plurality of Rs independently represent a hydrogen atom or a methyl group, and * represents a bond)].

As a seventh aspect, the composition for forming a flexible element substrate according to the fifth aspect or claim 6, wherein the fluorine-containing aromatic diamine contains the diamine represented by the formula (A1).

[Chemical 3] H ₂ NB ² -NH ₂ (A1)

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

(In the formula, * represents a bond portion).

As an eighth viewpoint, the composition for forming a flexible element substrate according to any one of the first viewpoint to the seventh viewpoint, wherein the mass ratio of the polyimide to the silicon dioxide particle is 7:3 ~3:7.

As a ninth viewpoint, the composition for forming a flexible element substrate according to any one of the first viewpoint to the eighth viewpoint, wherein the silicon dioxide The average particle diameter of the particles is 60 nm or less.

As a tenth viewpoint, the composition for forming a substrate for a flexible element according to any one of the first viewpoint to the ninth viewpoint is a composition for forming a substrate for a flexible element to which a laser lift-off method is applied.

As an 11th viewpoint, it is related with the flexible element board|substrate formed with the composition for flexible element board|substrate formation in any one of a 1st viewpoint - a 10th viewpoint.

As a twelfth aspect, it relates to a method for producing a flexible element substrate, which comprises applying the composition for forming a flexible element substrate according to any one of the first aspect to the tenth aspect on a substrate, Dry. The step of forming a flexible element substrate by heating, and the peeling step of peeling the flexible element substrate from the substrate by a laser lift-off method.

According to the composition for forming a flexible element substrate according to the present invention, the composition has a low coefficient of linear expansion with good reproducibility, excellent heat resistance, high transparency and low retardation, and is excellent in flexibility, especially It is a substrate for flexible devices such as flexible displays that fully absorb the light of a specific wavelength (308nm) that can be applied to the laser lift-off method.

In addition, the flexible element substrate of the present invention has various properties required for a substrate for displaying flexible elements such as flexible displays, that is, a low coefficient of linear expansion, high transparency in the visible light region (high light through High yield, low yellowness), low retardation, and excellent flexibility, in particular, it can fully absorb light of a specific wavelength (308nm), and the laser lift-off method is suitable for peeling off the substrate from the carrier substrate.

The present invention as described above is a substrate for flexible elements requiring properties such as high flexibility, low coefficient of linear expansion, high transparency (high light transmittance, low yellowness), and low retardation, especially in the manufacturing steps thereof, The possibility of adopting the laser lift-off method can fully correspond to the progress in the field of substrates for flexible devices.

Hereinafter, the present invention will be described in detail.

The composition for forming a flexible element 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 is preferably imidized so that a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic A polyimide obtained by imidizing a polyimide obtained by reacting a diamine component of a fluorine-containing aromatic diamine. That is, the above-mentioned polyimide is preferably an imide of a polyamic acid, and the polyamic acid system includes a tetracarboxylic dianhydride component of an alicyclic tetracarboxylic dianhydride and a fluorine-containing aromatic dianhydride. The reactant of the diamine component of the amine.

Among them, it is preferable that the above-mentioned alicyclic tetracarboxylic dianhydride contains the following formula In the case of the tetracarboxylic dianhydride represented by (C1), the above-mentioned fluorine-containing aromatic diamine contains the diamine represented by the following formula (A1).

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

(in the formula, a plurality of Rs independently represent a hydrogen atom or a methyl group, and * represents a bonding portion)].

[Chemical 11] H ₂ NB ² -NH ₂ (A1)

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

(In the formula, * represents a bond portion).

Among the tetracarboxylic dianhydrides represented by the above formula (C1), B ¹ in the formula is preferably a compound represented by the formulae (X-1), (X-4), (X-6), (X-7) .

In addition, among the diamines represented by the above formula (A1), it is preferable that B ² in the formula is a compound represented by the formulae (Y-12) and (Y-13).

As a suitable example, a polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride represented by the above formula (C1) with a diamine represented by the above formula (A1) includes: A monomer unit represented by the formula (2) described later.

In order to obtain a resin film suitable for a flexible device substrate having low coefficient of linear expansion, low retardation and high transparency, and excellent flexibility, which is the object of the present invention, the total moles relative to the tetracarboxylic dianhydride component The alicyclic tetracarboxylic dianhydride, for example, preferably the tetracarboxylic dianhydride represented by the above formula (C1) is 90 mol% or more, more preferably 95 mol% or more, especially all (100 mol%) ) is the most suitable tetracarboxylic dianhydride represented by the above formula (C1).

Also, in order to obtain the aforementioned resin film having the above-mentioned characteristics of low coefficient of linear expansion, low retardation, and high transparency, and excellent flexibility, a fluorine-containing aromatic diamine is preferably, for example, relative to the total moles of the diamine component. The diamine represented by the above formula (A1) is 90 mol% or more, more preferably 95 mol% or more. Moreover, the whole (100 mol%) of the diamine component may be the diamine represented by the said formula (A1).

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

As a monomer unit represented by said formula (2), what is represented by formula (2-1) or formula (2-2) is preferable, and what is represented by formula (2-1) is more preferable.

The polyimide used in the present invention is composed of an alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the aforementioned formula (C1) and a diamine component containing the diamine represented by the formula (A1). In addition to the derived monomer units, other monomer units may also be included. The content ratio of this other monomer unit is arbitrarily determined without impairing the properties of the resin film suitable as a flexible element substrate formed from the composition of the present invention. The ratio is relative to the monomer unit derived from the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the aforementioned formula (C1) and the diamine component containing the diamine represented by the formula (A1) The total moles of , preferably less than 20 mol %, more preferably less than 10 mol %, still more preferably less than 5 mol %.

As such another monomer unit, although the monomer unit represented by Formula (3) is mentioned, for example, it is not limited to this.

In formula (3), A represents a tetravalent organic group, preferably a tetravalent group represented by any one of the following formulae (A-1) to (A-4). Moreover, in said Formula (3), B represents a divalent organic group, Preferably it is a divalent group represented by any of Formulas (B-1)-(B-11). In each formula, * represents a bond portion. Furthermore, in the formula (3), when A is a tetravalent group represented by any one of the following formulae (A-1) to (A-4), B can be the aforementioned formula (Y-1) to ( A divalent base represented by any one of Y-34). Or in the formula (3), when B is a divalent group represented by any one of the following formulae (B-1) to (B-11), A can be the aforementioned formula (X-1) to (X -12) The tetravalent base represented by any one of them.

When the polyimide of the present invention contains the monomer unit represented by the formula (3), A and B may contain, for example, a monomer unit constituted by only one of the groups exemplified by the following formula, and A and At least one of B may contain two or more monomer units selected from two or more groups exemplified below.

Furthermore, in the polyimide used in the present invention, the monomer units are linked in an arbitrary order.

In addition, the polyimide used in the present invention is composed of the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the aforementioned formula (C1) and the second component containing the diamine represented by the formula (A1). In the case where other monomer units represented by the above formula (3) are contained in addition to the monomer unit derived from the amine component, the polyimide containing each monomer unit can be made as a tetracarboxylic acid by imidization. The tetracarboxylic dianhydride represented by the above formula (C1) and the tetracarboxylic dianhydride represented by the following formula (5) as the acid dianhydride component, and the diamine represented by the above formula (A1) as the diamine component, and the following A polymer obtained by polymerizing the diamine represented by the formula (6) in an organic solvent Amidic acid is obtained by imidization.

A in the above formula (5) and B in the formula (6) have the same meanings as A and B in the above-mentioned 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'-diphenyl bisulfite 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-tetraketone), 6,6'-bis(trifluoromethyl)-[5,5'-biisobenzofuran ]-1,1',3,3'-tetraketone, 4,6,10,12-tetrafluorodifuro[3,4-b:3',4'-i]dibenzo[b,e ][1,4]Dioxin-1,3,7,9-tetraketone, 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 tetracarboxylic acids such as 3-dioxo-1,3-dihydroisobenzofuran-5-carboxamide); 1,2-dimethyl-1,2,3,4-cyclobutane Tetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid di Anhydrides, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid dianhydride, etc. Carboxylic dianhydride; Aliphatic tetracarboxylic dianhydride, such as 1, 2, 3, 4- butane tetracarboxylic dianhydride, are not limited to these.

Among these, it is preferable that A in the formula (5) is a tetracarboxylic dianhydride of a tetravalent group represented by any one of the aforementioned formulas (A-1) to (A-4), that is, 11, 11-bis(trifluoromethyl)-1H-difluoro[3,4-b:3',4'-i]xanthene-1,3,7,9-(11H-tetraketone), 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(trifluoro Methoxy)benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetraone is a preferred compound.

Moreover, as the diamine represented by the formula (6), for example, 2-(trifluoromethyl)benzene-1,4-diamine, 5-(trifluoromethyl)benzene-1,3-diamine, 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 , 4-(trifluoromethyl)-1,4-phenylenediamine, 2-(trifluoromethyl)-1,3-phenylenediamine, 4-(trifluoromethyl)-1,3-phenylenediamine , 2-methoxy-1,4-phenylenediamine, 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)di Aniline, 4,4'-oxybis[3-(trifluoromethyl)aniline], 1,4-bis(4-aminophenoxy)benzene, 1,3'-bis(4-aminobenzene) oxy)benzene, 1,4-bis(3-aminophenoxy)benzene, benzidine, 2-methylbenzidine, 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'-dihydroxy Benzidine, 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'-Diaminobenzidine, 4-aminophenyl-4'-amino Parabens, Octafluorobenzidine, 2,2',5,5'-Tetramethylbenzidine, 3,3',5,5'-Tetramethylbenzidine, 2,2',5,5 '-4(trifluoromethyl)benzidine, 3,3',5,5'-4(trifluoromethyl)benzidine, 2,2',5,5'-tetrachlorobenzidine, 4,4 '-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-{[3,3"-bis(tris) Fluoromethyl)-(1,1':3',1"-terphenyl)-4,4"-diyl]-bis(oxy)}diphenylamine, 4,4'-{[(perfluoropropane -2,2-Diyl)bis(4,1-phenylene)]bis(oxy)}diphenylamine, 1-(4-aminophenyl)-2,3-dihydro-1,3, Aromatic diamines such as 3-trimethyl-1H-indene-5 (or 6) amine; 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(3- Methylcyclohexylamine), isophoronediamine, trans-1,4-cyclohexanediamine, cis-1,4-cyclohexanediamine, 1,4-cyclohexanebis(methyl) amine), 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-amino) cyclohexyl) hexafluoropropane, 1,3-propanediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1, Aliphatic diamines such as 7-heptamethylenediamine, 1,8-octamethylenediamine, and 1,9-nonamethylenediamine are not limited to these.

Among these, B in the formula (6) is preferably an aromatic diamine in which B is a divalent group represented by any of the aforementioned formulas (B-1) to (B-11), that is, 2,2 '-Bis(trifluoromethoxy)-(1,1'-biphenyl)-4,4'-diamine [alias: 2,2'- dimethoxybenzidine], 4,4'-(perfluoropropane-2,2-diyl)diphenylamine, 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 [alias: 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)}diphenylamine, 4,4'-{[(perfluoropropane-2,2-diyl)bis(4,1-phenylene)]bis (oxy)}diphenylamine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5(or 6)amine as the preferred two amine.

The content of the above-mentioned polyimide is usually 10 mass % or more, preferably 20 mass % or more with respect to the total solid mass of the flexible element substrate-forming composition from the viewpoint of the mechanical strength of the formed film. , more preferably 25 mass % or more, from the viewpoint of the optical properties of the low retardation film (thickness-direction retardation (R _th ) and coefficient of linear expansion (CTE) do not decrease), usually 80 mass % or less, preferably 75 mass % or less, more preferably 70 mass % or less. Furthermore, the term "solid content" means a component remaining after removing the solvent from all the components constituting the composition for forming a flexible element substrate.

<Synthesis of Polyamide>

As described above, the polyimide used in the present invention is composed of a tetracarboxylic dianhydride component containing the alicyclic tetracarboxylic dianhydride represented by the above formula (C1) and a fluorine-containing aromatic compound containing the above formula (A1) The polyamide acid obtained by reacting the diamine component of the family of diamines is obtained by imidization.

The reaction to obtain polyamide from the above two components can be easier than that of organic It is advantageous to carry out in a solvent and to not generate by-products.

The incorporation ratio (molar ratio) of the tetracarboxylic dianhydride component and the diamine component in such a reaction is considering the molecular weight of the polyimide obtained by imidizing the polyimide afterward. If it is set appropriately, the tetracarboxylic dianhydride component is usually about 0.8 to 1.2, for example, about 0.9 to 1.1, preferably about 0.95 to 1.02, relative to the diamine component 1 . As in the usual polycondensation reaction, the molecular weight of the polyamic acid produced is larger as the molar ratio is closer to 1.0.

The organic solvent used in the reaction of the tetracarboxylic dianhydride component and the diamine component is not particularly limited as long as it does not adversely affect the reaction and dissolves the produced polyamide. Specific examples thereof are listed 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-dimethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-propoxy base-N,N-dimethylpropionamide, 3-isopropoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, 3- sec-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, γ -butyrolactone, N-methylcaprolactone , dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfoxide, hexamethyl sulfoxide, isopropanol, 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 ethyl Acid esters, butyl carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetic acid Esters, Propylene Glycol Monomethyl Ether, Propylene Glycol-tert-Butyl Ether, Dipropylene Glycol Monomethyl Ether, Diethylene Glycol, Diethylene Glycol Monoacetate, Diethylene Glycol Dimethyl Ether, Dipropylene Glycol Monoethyl Ester 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, diisobutene , pentyl 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, Methylethyl 3-Ethoxypropionate, Ethyl 3-Methoxypropionate, 3-Ethoxypropionate acid, 3-methoxypropionate, 3-methoxypropionate, 3-methoxypropionate, 3-methoxypropionate, 3-methoxypropionate, Diethylene glycol dimethyl ether (Diglyme), 4-hydroxy-4-methyl- 2-pentanone, etc., but not limited to these. These can be used individually or in combination of 2 or more types.

Furthermore, even if it is a solvent which cannot melt|dissolve a polyamic acid, in the range which does not precipitate the produced polyamic acid, you may mix and use it with the said solvent. In addition, since the moisture in the organic solvent inhibits the polymerization reaction and further causes the hydrolysis of the produced polyamic acid, the organic solvent is preferably dehydrated and dried as much as possible.

As the above-mentioned tetracarboxylic dianhydride component and diamine component, there are As a method of carrying out the reaction in an organic solvent, for example, a dispersion or solution in which the diamine component is dispersed or dissolved in the organic solvent is stirred, and the tetracarboxylic dianhydride component is directly added or added to disperse or dissolve the component in the organic solvent. The former method, on the other hand, the method of adding the diamine component to a dispersion or solution in which the tetracarboxylic dianhydride component is dispersed or dissolved in an organic solvent, and the method of alternately adding the tetracarboxylic dianhydride component and the diamine compound component, etc., as long as the obtained The intended polyamide is not limited to these methods.

In addition, when the tetracarboxylic dianhydride component and/or the diamine component are composed of a plurality of compounds, they can be reacted in a premixed state, they can be reacted individually in order, and they can be reacted individually. The low molecular weight body is mixed and reacted as a high molecular weight body.

The temperature during the synthesis of the above-mentioned polyamic acid can be appropriately set in the range from the melting point to the boiling point of the above-mentioned solvent to be used. 100°C, usually about 0 to 100°C, preferably about 0 to 70°C.

The reaction time depends on the reaction temperature and the reactivity of the raw material, and cannot be uniformly defined, but is usually about 1 to 100 hours.

In addition, although the reaction can be carried out with any raw material concentration, when the concentration is too low, it is difficult to obtain a high molecular weight polyamic acid. When the concentration is too high, the viscosity of the reaction solution becomes too high and it is difficult to uniformly stir, so tetracarboxylic acid The total concentration in the reaction solution of the dianhydride component and the diamine component is preferably 1 to 50 mass %, more preferably 5 to 40 mass %. Furthermore, if necessary, the initial stage of the reaction can be carried out at a high concentration, and then an organic solvent can be added.

<Imidation of Polyamides>

As a method of imidizing a polyamic acid, thermal imidization in which a solution of polyamic acid is directly heated, and catalytic imidization in which a catalyst is added to a solution of polyamic acid can be mentioned.

The temperature of the thermal imidization of the polyamic acid in the solution is 100°C to 400°C, preferably 120°C to 250°C, while the water generated due to the imidization reaction is excluded from the system. better.

The chemical (catalyst) imidization of polyamide can be performed by adding alkaline catalyst and acid anhydride to the solution of polyamide, and stirring the system at a temperature of -20~250℃, preferably 0~180℃ Do it inside.

The amount of the alkaline catalyst is 0.5-30 mole times of the amino acid group of the polyamide acid, preferably 1.5 to 20 mole times, and the amount of the acid anhydride is 1～30 mole times of the amino acid group of the polyamide acid. 50 mole times, preferably 2 to 30 mole times.

Examples of the basic catalyst include amines such as pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and 1-ethylpiperidine. Among them, pyridine is used to advance the reaction. It is better to have moderate alkalinity.

Examples of the acid anhydride include aliphatic carboxylic acid anhydrides such as acetic anhydride, and aromatic carboxylic acid anhydrides such as trimellitic anhydride and pyromellitic anhydride. Among them, acetic anhydride is preferred because purification after completion of the reaction is easy.

The imidization rate of the imidization by the catalyst can be adjusted by adjusting the amount of the catalyst, the reaction temperature and the reaction time.

In the polyimide used in the present invention, the dehydration ring closure rate (imidation rate) of the amide acid group does not necessarily have to be 100%, and can be adjusted arbitrarily according to the application or purpose. Excellent is more than 50%.

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

In addition, the polyimide used in the present invention is preferably polystyrene conversion by gel permeation chromatography (GPC) in consideration of the strength of the resin film, workability when forming the resin film, and uniformity of the resin film. The weight average molecular weight (Mw) is 5,000~200,000.

<Polymer Recovery>

When the polymer component is recovered and used from the reaction solution of polyamic acid and polyimide, the reaction solution may be poured into a poor solvent and precipitated. Examples of the poor solvent used for the precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, isopropanol, and water. The polymer precipitated by adding the poor solvent can be recovered by filtration, and then dried at normal temperature or by heating under normal pressure or reduced pressure.

In addition, repeating 2 to 10 times to re-dissolve the polymer recovered by precipitation in an organic solvent, during the re-precipitation recovery operation, can reduce the impurities in the polymer. As the poor solvent in this case, for example, when three or more kinds of poor solvents such as alcohols, ketones, and hydrocarbons are used, it is preferable to further improve the purification efficiency.

In the reprecipitation recovery step, the organic solvent for dissolving the resin component is not particularly limited. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactamide, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfite, hexamethylsulfite, 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 Esters, diethylene glycol dimethyl ether (Diglyme), 4-hydroxy-4-methyl-2-pentanone, etc. Two or more kinds of these solvents can be mixed and used.

[Titanium dioxide]

Although the titanium dioxide used in the present invention is not particularly limited, titanium dioxide in particle form can be suitably used, for example, the particle diameter is 3nm-200nm, preferably 3nm-50nm, more preferably 3nm-20nm. By using titanium dioxide particles having a particle size within such a numerical range, the substrate peeling by the laser lift-off method can be performed with higher accuracy and higher reproducibility.

In the present invention, the particle diameter of the titanium dioxide particles is expressed as the primary particle diameter of the titanium dioxide particles in the titanium dioxide sol described later as observed by an electron microscope.

As titanium dioxide, although it can have anatase type, rutile type, and anatase type. Any of a rutile mixed type and a brookite type of crystal structure, but among these, it is desirable to include a rutile type.

In particular, in the present invention, titanium dioxide-based colloidal particles (colloidal titanium dioxide) having the above-mentioned particle diameter can be suitably used, and titanium dioxide sol can be used as the colloidal titanium dioxide.

The titanium dioxide-based colloidal particles used in the present invention may be independent colloidal particles, or may be a mixture with other high-refractive-index-based metal oxides described later, or composite oxide colloidal particles.

The manufacturing method of the said titanium dioxide type|system|group colloid particle is not specifically limited, For example, 1) an ion exchange method, 2) a decoagulation method, etc. can be manufactured by a conventional method.

1) Ion exchange method: a method of treating an acidic salt of titanium with a hydrogen-type ion-exchange resin, or a method of treating a basic titanium salt with a hydroxyl-type anion-exchange resin can be used.

2) Decoagulation method: a method of decoagulation with acid or alkali after neutralizing the acid salt of titanium with salt, or washing the gel obtained by neutralizing the basic salt of titanium with acid, and then decoagulation with acid or alkali ( Japanese Patent Publication No. 4-27168), or a method for hydrolyzing titanium alkoxides (Japanese Patent Publication No. 2003-176120), or a method for hydrolyzing the above-mentioned basic salts of titanium under heating (Japanese Patent Publication No. 10-245224) Gazette) etc.

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 , Bi ₂ O ₃ , SrO, and the like can be produced in the same manner as the above-mentioned titanium dioxide-based colloidal particles. Further, examples of the composite oxide include TiO ₂ -SnO ₂ , TiO ₂ -ZrO ₂ , TiO ₂ -ZrO ₂ -SnO ₂ , TiO ₂ -ZrO ₂ -CeO ₂ and the like. The methods disclosed in Japanese Patent Laid-Open No. 2014-38293, Japanese Patent Laid-Open No. 2001-122621, Japanese Patent Laid-Open No. 2000-063119, etc. are used.

Examples of the organic solvent in the above-mentioned titanium dioxide sol include lower alcohols such as methyl alcohol, ethyl alcohol, and isopropanol; N,N-dimethylformamide, N,N-dimethylacetamide, and the like. Linear amides such as amines; cyclic amides such as N-methyl-2-pyrrolidone; ethers such as γ-butyrolactone; glycols such as ethyl cellosolve, ethylene glycol, Acetonitrile, etc.

The viscosity of the above titanium dioxide sol is 0.6mPa at 20℃. s~100mPa. s around.

Examples of commercial products of the above-mentioned titanium dioxide-based colloidal particles (titanium dioxide sol) include trade name neutral titanium dioxide sol TTO-W-5 (aqueous sol of rutile type ultrafine titanium oxide, silica surface treatment, Ishihara Sangyo Co., Ltd.), trade name TKS-201 (anatase acid sol, manufactured by Tayca Corporation), trade name KS-202 (anatase acid sol, manufactured by Tayca Corporation), trade name TKS-203 (Anatase type neutral sol, manufactured by Tayca Co., Ltd.), trade name CSB (anatase type aqueous acid sol, manufactured by Sakai Chemical Industry Co., Ltd.), trade name CSB-M (anatase type aqueous neutral sol, Sakai) Chemical Industry Co., Ltd.), trade names DC-Ti, DCN-Ti, DCB-Ti (the above are amorphous water-based sols, manufactured by Fuji Titanium Industries Co., Ltd.), organic sols (anatase type, solvent: ethylene glycol) Alcohol, toluene-IPA, Fuji Titanium Industry Co., Ltd.), brand name QUEEN TITANIC series (aqueous colloid, Nippon catalyst Chemical Co., Ltd.), trade name OPTALAKE series (non-aqueous colloid, Nikkor Chemical Co., Ltd.), trade name Sancolloid (registered trademark) HT-R350M7-20 (Nissan Chemical Industry Co., Ltd.), etc.

Furthermore, the titanium dioxide sol can be prepared by dispersing titanium dioxide particles in an organic solvent according to a conventional method.

As such an organic solvent, the thing similar to the above is mentioned.

As an example of a commercial item of a titanium dioxide particle, a brand name AEROXIDE (registered trademark) _TiO2 P25 (made by Japan Aerosil Co., Ltd.) etc. are mentioned.

The content of the above-mentioned titanium dioxide is usually 0.1 mass based on the total mass of the polyimide, titanium dioxide particles and silicon dioxide particles in the composition for forming a flexible element substrate from the viewpoint of ensuring absorption of light having a wavelength of 308 nm % or more, preferably 1 mass % or more, more preferably 2 mass % or more, and usually 30 mass % or less, preferably 25 mass %, from the viewpoint of obtaining a film having excellent transparency in the visible light region with good reproducibility mass % or less, more preferably 20 mass % or less.

Furthermore, in the case where the composition for forming a flexible element substrate of the present invention contains a crosslinking agent to be described later, the amount of polyimide, titanium dioxide particles and dioxide in the composition for forming a flexible element substrate is relatively low. As for the total mass of the silicon particles, the content of the titanium dioxide is preferably set to be 3 mass % or more and 16 mass % or less.

[Silicon dioxide]

Although the silicon dioxide (silicon dioxide) used in the present invention is not particularly limited Although the particle form of silica, for example, the average particle diameter is 100 nm or less, preferably 5 nm to 100 nm, more preferably 5 nm to 55 nm, from the viewpoint of obtaining a more transparent film with good reproducibility, it is preferred It is 5nm~50nm, more preferably 5nm~45nm, still more preferably 5nm~35nm, still more preferably 5nm~30nm.

In the present invention, the mean particle diameter of the silica particles refers to the mean particle diameter value calculated from the specific surface area value measured by the nitrogen adsorption method using the silica particles.

Especially in this invention, the colloidal silica which has the value of the said average particle diameter can be used suitably, and a silica sol can be used as this 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 organic silica sol obtained by substituting water as a dispersing medium of the aqueous silica sol with an organic solvent can be used. Silica sol.

In addition, alkoxysilanes such as methyl silicate or ethyl silicate can also be used as catalysts (such as alkali catalysts such as ammonia, organic amine compounds, sodium hydroxide, etc.) in organic solvents such as alcohols. Hydrolysis is carried out in the presence of, and the silica sol obtained by condensation, or the silica sol solvent thereof is replaced with an organic silica sol of other organic solvents. This substitution can be carried out by ordinary methods such as distillation, ultrafiltration, and the like.

Among them, the present invention preferably uses an organic silica sol in which the dispersion medium is an organic solvent.

Examples of the organic solvent for the above-mentioned organic silica sol include lower alcohols such as methyl alcohol, ethyl alcohol, and isopropanol; N,N- Linear amides such as dimethylformamide and N,N-dimethylacetamide; cyclic amides such as N-methyl-2-pyrrolidone; ethers such as γ-butyrolactone ; Ethyl cellosolve, glycols such as ethylene glycol, acetonitrile, etc.

The viscosity of the above organic silica sol is 0.6mPa at 20℃. s~100mPa. s around.

Examples of commercial products of the above-mentioned organic silica sol include trade names MA-ST-S (methanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade names MT-ST (methanol-dispersed silica sols), and trade names. Silica sol, Nissan Chemical Industry Co., Ltd.), trade name MA-ST-UP (methanol-dispersed silica sol, Nissan Chemical Industry Co., Ltd.), trade name MA-ST-M (methanol-dispersed dioxide Silica sol, Nissan Chemical Industry Co., Ltd.), trade name MA-ST-L (methanol-dispersed silica sol, Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-S (isopropanol-dispersed dioxide Silica sol, Nissan Chemical Industry Co., Ltd.), trade name IPA-ST (isopropanol-dispersed silica sol, Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-UP (isopropanol-dispersed dioxide Silica sol, Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-L (isopropanol-dispersed silica sol, Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-ZL (isopropanol-dispersed silica sol) 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 sol) Acid ethyl dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name PMA-ST (propylene glycol monomethyl ether acetate-dispersed silica sol, manufactured by 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 (methyl ethyl ketone dispersed silica sol, Nissan Chemical Industry Co., Ltd.) and trade name MIBK-ST (methyl isobutyl ketone dispersed silica sol, Nissan Chemical Industry Co., Ltd.) (stock) system), etc., but not limited to these.

In the present invention, as for the silica, for example, the silicas listed in the above-mentioned products used as the organic silica sol can be used in combination of two or more kinds.

From the viewpoint of obtaining a thin film with low retardation and low coefficient of linear expansion with good reproducibility, the content of the above-mentioned silicon dioxide is relative to the polyimide, titanium dioxide particles and dioxide in the composition for forming a flexible device substrate. The total mass of the silicon particles is usually 20 mass % or more, preferably 30 mass % or more, more preferably 40 mass % or more, and from the viewpoint of the mechanical strength of the film, usually 80 mass % or less, preferably 75 mass % mass % or less, more preferably 70 mass % or less.

[Crosslinking agent]

The composition for forming a flexible element substrate of the present invention may further contain a cross-linking agent, and the cross-linking agent used here is composed of a compound consisting of only hydrogen atoms, carbon atoms, nitrogen atoms and oxygen atoms It consists of two or more groups selected from the group consisting of a hydroxyl group, an epoxy group, and an alkoxy group having 1 to 5 carbon atoms, and has a ring structure. by using such The cross-linking agent not only provides excellent solvent resistance with good reproducibility, but also is suitable for resin films of flexible element substrates, and can realize a flexible element substrate forming composition with improved storage stability.

Among them, in terms of the total number of hydroxyl groups, epoxy groups, and alkoxy groups having 1 to 5 carbon atoms per compound of the crosslinking agent, from the viewpoint of realizing the solvent resistance of the obtained resin film with good reproducibility, It is preferably 3 or more, and from the viewpoint of realizing the flexibility of the obtained resin 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 crosslinking agent include aryl rings such as benzene, nitrogen atom-containing heteroaryl rings such as pyridine, pyrazine, pyrimidine, pyridazine, 1,3,5-triazine, Cycloalkane rings such as cyclopentane, cyclohexane, cycloheptane, etc., cyclic amines such as piperidine, piperazine, hexahydropyrimidine, hexahydropyridazine, hexahydro-1,3,5-triazine, etc.

If the number of ring structures per compound of the crosslinking agent is 1 or more, it is not particularly limited, but from the viewpoint of securing the solubility in the solvent of the crosslinking agent and obtaining a resin film with high flatness Preferably 1 or 2.

In addition, when there are two or more ring structures, the ring structures can be condensed with each other, and alkanes having 1 to 5 carbon atoms such as methylene, ethylidene, trimethylene, propane-2,2-diyl, etc. The ring structures of linking groups such as diradicals can be bonded to each other.

The molecular weight of the cross-linking agent is not particularly limited as long as it has cross-linking ability and is soluble in the solvent used. However, the solvent resistance of the obtained resin film, the solubility to the organic solvent of the cross-linking agent itself, and the choice are considered. In the case of availability, price, etc., it is preferably about 100 to 500, more preferably about 150 to 400.

The crosslinking agent may further have a group which can be derived from a ketone group, an ester group (bonding) or the like, a hydrogen atom, a carbon atom, a nitrogen atom, and an oxygen atom.

Preferred examples of the crosslinking agent include compounds represented by the formula selected from the group consisting of the following formulae (K1) to (K5), and one of preferred embodiments of the formula (K4) includes The compound represented by the formula (K4-1) can be exemplified by the compound represented by the formula (5-1) as one of the preferred embodiments of the formula (K5).

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 methylene group, ethylidene group, trimethylene group, propane-2,2-diyl group, etc., wherein, As A ¹ , a methylene group and an ethylidene group are preferable, and a methylene group is more preferable, and as A ² , a methylene group and a propane-2,2-diyl group are preferable.

Each X series independently of each other represents hydroxyl, epoxy (oxa-cyclopropyl), or methoxy, ethoxy, 1-propyloxy, isopropyloxy, 1-butyloxy, t - Alkoxy group having 1 to 5 carbon atoms such as butyloxy group.

Among them, when considering the availability and price of the crosslinking agent, X is preferably an epoxy group in formulas (K1) and (K5), and preferably has 1 carbon atom in formulas (K2) and (K3). The alkoxy group of ~5, in formula (K4), is preferably a hydroxyl group.

In 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, but preferably 2 to 3, more preferably 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 formulae (K1) to (K5) can be obtained by combining a skeleton compound having an aryl compound, a heteroaryl compound, a cyclic amine, etc. having the same ring structure as the ring structure in each of these compounds with an epoxy compound. Halogenated alkyl compounds, alkoxy halide compounds, etc. are obtained by reacting carbon-carbon coupling reaction or N-alkylation reaction, or by hydrolyzing the alkoxy moiety of the resultant.

As the crosslinking agent, a commercially available product may be used, or one synthesized by a known synthesis method may be used.

Examples of commercial products include CYMEL (registered trademark) 300, the same 301, the same 303LF, the same 303ULF, the same 304, the same 350, the same 3745, the same XW3106, the same MM-100, the same 323, the same 325, the same 327, the same 328, same 385, same 370, same 373, same 380, same 1116, same 1130, same 1133, same 1141, same 1161, same 1168, same 3020, Same as 202, same as 203, same as 1156, same as MB-94, same as MB-96, same as MB-98, same as 247-10, same as 651, same as 658, same as 683, same as 688, same as 1158, same as MB-14, same as same as MI-12-I, same as MI-97-IX, same as U-65, same as UM-15, same as U-80, same as U-21-511, same as U-21-510, same as U-216-8, same as U-216-8 U-227-8, same as U-1050-10, same as U-1052-8, same as U-1054, same as U-610, same as U-640, same as UB-24-BX, same as UB-26-BX, same as U-640 UB-90-BX, same as UB-25-BE, same as UB-30-B, same as U-662, same as U-663, same as U-1051, same as UI-19-I, same as UI-19-IE, same as UI-21-E, same as UI-27-EI, same as U-38-I, same as UI-20-E, same as 659, same as 1123, same as 1125, same as 5010, same as 1170, same as 1172, same as NF3041, same as NF2000, etc. (The above is manufactured by Allnex Corporation); TEPIC (registered trademark) V, the same as S, the same as HP, the same as L, the same as PAS, the same as VL, the same as UC (the above are manufactured by Nissan Chemical Industry Co., Ltd.), TM-BIP-A ( Asahi Organic Materials Industry Co., Ltd.), 1,3,4,6-(methoxymethyl) glycol urea (hereinafter referred to as TMG) (Tokyo Chemical Industry Co., Ltd.), 4,4'- Methylene bis(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-6000, HP-4710, EXA-4850-150, EXA-4850-1000, EXA-4816, HP-820 (DIC (stock)), TG-G (Shikoku Chemical Industry Co., Ltd.) (shares)), etc.

Hereinafter, as a crosslinking agent, although preferable specific examples are given, it is not limited to these.

Although the compounding amount of the cross-linking agent is appropriately determined according to the type of the cross-linking agent, etc., it cannot be specified in general, but generally the resin obtained from the total mass of the aforementioned polyimide, the aforementioned titanium dioxide, and the aforementioned silicon dioxide is determined. From the viewpoint of securing the flexibility of the film and suppressing brittleness, it is 50 mass % or less, preferably 100 mass % or less, and from the viewpoint of securing the solvent resistance of the obtained resin film, it is 0.1 mass % Above, preferably 1 mass % or more.

[Organic solvents]

The composition for forming a flexible device substrate of the present invention contains an organic solvent in addition to the aforementioned polyimide, titanium dioxide, silicon dioxide and, if necessary, a crosslinking agent. This organic solvent is not specifically limited, For example, the same as the specific example of the reaction solvent used at the time of preparation of the said polyamic acid and polyimide can be mentioned. More specifically, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazoline can be mentioned ketone, N-ethyl-2-pyrrolidone, γ -butyrolactone, etc. Furthermore, the organic solvent may be used alone or in combination of two or more.

Among these, in consideration of good reproducibility and obtaining a resin film with high flatness, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and γ -butyrolactone are preferable.

[Composition for forming flexible element substrate]

The present invention is a composition for forming a flexible device substrate comprising the aforementioned polyimide, titanium dioxide, silicon dioxide, an organic solvent, and a cross-linking agent if necessary. Here, the composition for forming a flexible element substrate of the present invention is a uniform one and is not subject to phase separation.

In the composition for forming a flexible device substrate of the present invention, the mixing ratio of the polyimide to the silicon dioxide is preferably polyimide: silicon dioxide=10:1~1:10, More preferably, it is 8:2~2:8, for example, 7:3~3:7.

Moreover, although the solid content in the composition for forming a flexible element substrate of the present invention is usually in the range of 0.5 to 30 mass %, from the viewpoint of the uniformity of the film, it is preferably 5 mass % or more and 20 mass % or more. mass % or less. Furthermore, the term "solid content" means a component remaining after removing the solvent from all the components constituting the composition for forming a flexible element substrate.

Furthermore, although the viscosity of the composition for forming a flexible element substrate is appropriately determined in consideration of the coating method used, the thickness of the resin film to be produced, etc., it is usually 1 to 50,000 mPa at 25°C. s.

In the composition for forming a flexible element substrate of the present invention In order to impart processing characteristics or various functionalities, various organic or inorganic low molecular or high molecular compounds can be blended. For example, catalysts, antifoaming agents, 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 or linear expansion coefficient of the resin film.

The composition for forming a flexible device substrate of the present invention can be obtained by dissolving the polyimide, titanium dioxide and silicon dioxide obtained by the above-mentioned method, and, if necessary, a cross-linking agent in the above-mentioned organic solvent, and Titanium dioxide, silicon dioxide, and, if necessary, a cross-linking agent can be added to the prepared reaction solution of polyimide, and the aforementioned organic solvent can be further added if necessary.

[Flexible element substrate]

By applying the above-described composition for forming a flexible element substrate of the present invention to a substrate, it is dried. Heating and removing the organic solvent can obtain a resin film with high heat resistance, high transparency, moderate flexibility, moderate linear expansion coefficient, and small retardation, which selectively absorbs light with a wavelength of 308 nm, that is, a flexible element substrate.

And the above-mentioned flexible element substrate, that is, the flexible element substrate containing the above-mentioned polyimide, the above-mentioned titanium dioxide, silicon dioxide and a cross-linking agent if necessary, is formed by the flexible element substrate of the present invention. A flexible device substrate formed of a cured product of the composition is also an object of the present invention.

Examples of substrates used in the production of flexible element substrates (resin films) include plastics (polycarbonate, polymethacrylate, Polystyrene, polyester, polyolefin, epoxy, melamine, triacetyl cellulose, ABS, AS, norbornene-based resin, etc.), metal, stainless steel (SUS), wood, paper, glass, silicon wafer, Slate, etc.

In particular, when it is suitable for use as a flexible element substrate, from the viewpoint of the availability of existing equipment, it is preferable that the applicable substrates are glass and silicon wafers, and since the obtained flexible element substrate exhibits good peelability , so it is better to use glass. In addition, the linear expansion coefficient of the substrate to be applied is preferably 40 ppm/°C or lower, more preferably 30 ppm/°C or lower, from the viewpoint of the bending of the substrate after coating.

Although the coating method of the composition for forming a flexible element substrate on the base material is not particularly limited, for example, cast coating, spin coating, blade coating, dip coating, roll coating, bar coating, etc. may be mentioned. A coating method, a die coating method, an ink jet method, a printing method (relief, gravure, lithography, screen printing, etc.), etc., can be appropriately used according to the purpose.

The heating temperature is preferably 300°C or lower. When the temperature exceeds 300° C., the obtained resin film may become brittle, and in particular, a resin film suitable for use as a display substrate may not be obtained.

In addition, considering the heat resistance and linear expansion coefficient characteristics of the obtained resin film, it is desirable to heat the coated flexible element substrate forming composition at 40° C. to 100° C. for 5 minutes to 2 hours, and then directly use it in stages. The heating temperature rises, and finally it is heated at more than 175°C to 280°C for 30 minutes to 2 hours. In this way, by heating at a temperature of two or more stages of drying the solvent and promoting molecular alignment, the low thermal expansion characteristic can be expressed more reproducibly.

In particular, the coated flexible element substrate forming composition is preferably heated at 40°C to 100°C for 5 minutes to 2 hours, and then heated at more than 100°C to 175°C for 5 minutes to 2 hours. Heating over 175℃~280℃ for 5 minutes to 2 hours.

As for the apparatus used for heating, a hot plate, an oven, etc. are mentioned, for example. The heating environment can be under air, or under inert gas such as nitrogen, and it can be under normal pressure or under reduced pressure, and different pressures can be applied in each stage of heating.

The thickness of the resin film is in the range of about 1 to 200 μm, although it is appropriately determined in consideration of the type of flexible element, but especially if it is used as a substrate for flexible displays, it is usually about 1 to 60 μm. It is preferably about 5 to 50 μm, and the thickness of the coating film before heating is adjusted to form a resin film of a desired thickness.

The method of peeling the resin film formed in this way from the substrate is not particularly limited, and examples include a method of cooling the resin film to each substrate, adding a slit to the film for peeling, or a method of peeling off by applying tension through a roller. method etc.

Particularly in the present invention, a laser lift-off (LLO) method can be used as a method of peeling the resin film from the base material. That is, by irradiating the substrate with light having a wavelength of 308 nm from the surface opposite to the surface of the resin film forming the substrate, the light of this wavelength is transmitted through the substrate (eg, glass carrier), and only polyamides near the substrate are irradiated. The imine absorbs this light, and the resin film can be peeled off from the substrate by evaporating that part of the polyimide.

As the peeling of the resin film from the substrate by the laser peeling method The laser light used is not particularly limited, but excimer laser is preferred. As the specific vibration wavelength, ArF (193nm), KrF (248nm), XeCl (308nm), XeF (353nm), etc. can be listed. But especially preferred is XeCl (308 nm).

In addition, the energy density of the irradiated laser light is usually in the range of less than 650 mJ/cm ² , for example, in the range of 500 mJ/cm ² to 530 mJ/cm ² , the range of 500 mJ/cm ² to 515 mJ/cm ² , and the like. .

The resin film according to a preferred aspect of the present invention obtained in this manner can achieve high transparency with a light transmittance of 85% or more at a wavelength of 550 nm. On the other hand, when the light transmittance at the wavelength of 308 nm is 5% or less, the peeling of the resin film from the substrate to which the laser lift-off method is applied can be achieved, and sufficient light absorption at the wavelength can be achieved.

Furthermore, the resin film may have, for example, a coefficient of linear expansion at 30°C to 220°C of 40 ppm/°C or less, particularly a low value of 10 ppm/°C to 35 ppm/°C, which is excellent in dimensional stability during heating.

In addition, the in-plane retardation R ₀ and the thickness-direction retardation R _th of the resin film are characterized as being very small, and the in-plane retardation R ₀ is based on the birefringence (in-plane orthogonality) when the wavelength of the incident light is set to 590 nm. In the plane represented by the product of the difference between the two refractive indices) and the film thickness, the thickness-direction retardation R _th is based on the two birefringences (the two refractive indices in the plane and the thickness-direction) when viewed from a cross-section in the thickness direction. Each difference in the refractive index) is expressed as the average value of the two retardations obtained by multiplying the film thickness by the respective film thicknesses. When the average film thickness of the resin film is about 15 μm to 40 μm, the retardation R _th in the thickness direction is less than 700 nm, for example, 450 nm or less, for example, 1 nm to 410 nm, and the in-plane retardation R ₀ is less than 4.5, for example, 0.1~ 4.2, the birefringence Δn is less than 0.015, for example, it has a very low value of 0.0028 to 0.0144.

Since the resin film described above has the above-mentioned characteristics, it satisfies various conditions required as a base film of a substrate of a flexible device, and is particularly suitable for use as a base film of a substrate of a flexible device, especially a flexible display.

[Example]

Although an Example is given below and this invention is demonstrated in detail, this invention is not limited to these. Furthermore, the abbreviations of the reagents used, the devices used and their conditions are as follows.

<Measurement of Number Average Molecular Weight (Mn) and Weight Average Molecular Weight (Mw)>

Installation: Showa Denko Co., Ltd., Showdex GPC-101

Column: KD803 and KD805

Column temperature: 50℃

Dissolution solvent: DMF, flow rate: 1.5ml/min

Calibration Line: 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: gamma-butyrolactone

[Synthesis example of polyimide (I) (preparation example of polyimide solution (PI))]

In a three-necked reaction flask equipped with a nitrogen injection/discharge port, a Dean Stark device and a mechanical stirrer, TFMB 11.208g (0.035mol) and γ-butyrolactone (GBL) 66.56g were added, and stirring was started, and the temperature was raised to 90°C . After the diamine (TFMB) was completely dissolved in the solvent, 4.376 g (0.0175 moles) of BODAxx and 14.26 g of GBL were added, and the mixture was heated at 140° C. for 10 minutes under a nitrogen atmosphere. Then, 3.432 g (0.0175 mol) of CBDA and 14.26 g of GBL (γ-butyrolactone) were added and reacted under nitrogen atmosphere for 10 minutes. 0.152 g of 1-ethylpiperidine was added to the reactant, and the temperature was raised to 180° C. and maintained for 7 hours. GBL 86.02g was added to the reaction mixture, and it was diluted so that the solid content concentration (concentration of the composition excluding the organic solvent) became 10.5% by mass, and the intended polyimide solution (PI) (polyimide (I) was obtained. ) molecular weight: Mw=169,385, Mn=54,760).

[Preparation example of titanium dioxide sol (TiO ₂ -GBL)]

Into a 1000mL round-bottomed flask, put into methanol-dispersed titanium dioxide sol manufactured by Nissan Chemical Industry Co., Ltd.: _TiO2 -MeOH ("Sancolloid (registered trademark) HT-R305M7-20", rutile type, titanium dioxide solid content: 30.6% by mass ) 91.13g and γ -butyrolactone 82.02g. Then, the inside of the flask was depressurized by connecting the flask to a vacuum evaporator, immersed in a warm water bath at about 35°C for 60 minutes, and the solvent was methanol to obtain a titanium dioxide sol (TiO ₂ -GBL) substituted with γ -butyrolactone. ) about 107.0 g (titanium dioxide solid content concentration: 26.06 mass %).

Furthermore, in the above-mentioned titanium dioxide sol, the primary particle diameter of the titanium dioxide particles observed with an electron microscope is 10 to 12 nm.

[Preparation example of silica sol (GBL-M)]

A 1000 mL round-bottomed flask was put into methanol-dispersed silica sol: MA-ST-M 350 g (silicon dioxide solid content concentration: 40.4 mass %) and 419 g of γ -butyrolactone manufactured by Nissan Chemical Industries, Ltd. Then, by connecting the flask to a vacuum evaporator, the inside of the flask was depressurized, immersed in a warm water bath at about 35°C for 20 to 50 minutes, and the solvent was obtained from methanol to obtain a silica sol substituted by γ -butyrolactone ( GBL-M) about 560.3 g (silicon dioxide solid content concentration: 25.25 mass %). Furthermore, in the above silica sol, the average particle diameter calculated from the specific surface area value measured by the nitrogen adsorption method was 22 nm. More 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, and the measured specific surface area S (m ² /g) was used as D ( nm)=2720/S to calculate the average primary particle diameter.

[Preparation of composition for forming flexible element substrate]

[example 1]

At room temperature, the polyimide solution prepared in the synthesis example (PI, polyimide Imine solid content concentration: 10.5 mass %) 1 g was added to GBL-M silica sol (silicon dioxide solid content concentration: 25.25 mass %) 0.9703 g and GBL 0.946 g prepared in the preparation example, and stirred for 30 minutes to obtain a A composition for forming a flexible element substrate.

[Example 2]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.8316 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.1343 g, GBL 0.95 g, and stirred for 30 minutes to obtain a flexible element substrate forming composition.

[Example 3]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.5718 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.0503 g, GBL 0.5654 g, and stirred for 30 minutes to obtain a flexible element substrate forming composition.

[Example 4]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.5925 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.0302 g, GBL 0.5648 g, and stirred for 30 minutes to obtain a flexible element substrate forming composition.

[Example 5]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.6133 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.0100 g, GBL 0.5642 g, and stirred for 30 minutes to obtain a flexible element substrate forming composition.

[Example 6]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.6186 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.0050 g, GBL 0.5640 g, and stirred for 30 minutes to obtain a flexible element substrate forming composition.

[Example 7]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.37425 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.04029 g, GBL 0.335 g, and stirred for 30 minutes to obtain a composition for forming a flexible element substrate.

[Example 8]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.5718 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.05 g, GBL 1.264 g, TEPIC-L (purity 99%) 0.029 g was added, and stirred for 30 minutes, and then A composition for forming a flexible element substrate was obtained.

[Example 9]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.5198 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.1 g, GBL 1.266 g, and further added TEPIC-L (purity 99%) 0.029 g, stirred for 30 minutes, and A composition for forming a flexible element substrate was obtained.

[Example 10]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.4678 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.1511 g, GBL 1.268 g, and further added TEPIC-L (purity 99%) 0.029 g, and stirred for 30 minutes, and A composition for forming a flexible element substrate was obtained.

[Example 11]

At room temperature, 1 g of the polyimide solution (PI, polyimide solid content concentration: 10.5% by mass) prepared in the synthesis example was added to the GBL-M silica sol (silicon dioxide solid content) prepared in the preparation example. Concentration: 25.25 mass %) 0.5458 g, TiO ₂ -GBL titanium dioxide sol (titanium dioxide solid content concentration: 26.06 mass %) 0.0755 g, GBL 0.5654 g, and stirred for 30 minutes to obtain a flexible element substrate forming composition.

[Production of resin film]

Each of the flexible element substrate forming compositions obtained in Examples 1 to 10 was coated on a glass substrate, and the coating film was exposed to the atmosphere at 50°C for 30 minutes, 140°C for 30 minutes, 200°C for 60 minutes, and then -99kpa The resin film was obtained by sequential heating at 280°C for 60 minutes under vacuum.

The resulting film was mechanically cut and peeled for subsequent evaluation.

[Evaluation of thin films]

The heat resistance and optical properties of each resin film (evaluation sample) produced in the above process, that is, the coefficient of linear expansion (CTE) at 30°C to 220°C, 5% weight reduction temperature (Td _5% ), light The transmittance (T _{308 nm} , T _{550 nm} ) and CIEb ^* value (yellow evaluation), retardation (R _th , R ₀ ) and birefringence (Δn) were evaluated respectively according to the following procedure. The results are shown in Table 1.

1) Coefficient of Linear Expansion (CTE)

The film was cut into a size of 5 mm in width and 16 mm in length by using TMA Q400 manufactured by TA Instruments Co., Ltd., and the temperature was first heated at 10°C/min (first heating) to 50 to 300°C, and then at 10°C/min. Min cooling and cooling to 50℃, then heating at 10℃/min (second heating) to 30℃~420℃, second heating Linear expansion coefficient (CTE [ppm/℃) at 30℃~220℃ ]) to obtain the value. Furthermore, through the first heating, cooling and second heating, a load of 0.05N was added.

2) 5% weight reduction temperature (Td _5% )

The 5% weight loss temperature (Td _5% [°C]) is obtained by measuring about 5 to 10 mg of the thin film at 10°C/min to 50 to 800°C in nitrogen using TGA Q500 manufactured by TA Instruments.

3) CIE b value (CIE b ^* )

The CIE b value (CIE b ^* ) was measured using an SA4000 spectrometer manufactured by Nippon Denshoku Kogyo Co., Ltd. at room temperature with reference to air.

4) Light transmittance (transparency) (T _308nm , T _550nm )

The light transmittances (T _{308 nm} , T _{550 nm} [%]) at wavelengths of 308 nm and 550 nm were measured using a UV-3600 manufactured by Shimadzu Corporation at room temperature with reference to air.

5) Delay (R _th , R ₀ )

The retardation in the thickness direction (R _th ) and the in-plane retardation (R ₀ ) were measured at room temperature using KOBURA 2100ADH manufactured by Oji Scientific Instruments.

Furthermore, the retardation in the thickness direction (R _th ) and the in-plane retardation (R ₀ ) were calculated by the following equations.

R ₀ =(Nx-Ny)×d=△Nxy×d

R _th =[(Nx+Ny)/2-Nz]×d=[(△Nxz×d)+(△Nyz×d)/2

Nx, Ny: two refractive indices orthogonal to each other in the plane (Nx>Ny, Nx is also called the slow axis, and Ny is called the advance axis)

Nz: Refractive index in the (perpendicular) direction (perpendicular) to the face thickness

d: film thickness

△Nxy: Difference between two refractive indices in the plane (Nx-Ny) (birefringence)

△Nxz: The difference between the refractive index Nx in the plane and the refractive index Nz in the thickness direction (birefringence)

ΔNyz: The difference between the refractive index Ny in the plane and the refractive index Nz in the thickness direction (birefringence)

6) Film thickness (d)

The thickness of the obtained thin film was measured with a thickness gauge manufactured by Teclock.

7) Birefringence (△n)

The value of the retardation (R _th ) in the thickness direction obtained by the above-mentioned <5) retardation> was calculated by the following formula.

△N=[R _th /d(film thickness)]/1000

[Solvent resistance test]

At room temperature, the composition for forming a flexible element substrate obtained in Example 1, Example 3 and Example 10 was coated on a glass substrate, and on the resin film obtained by firing the coating film, TOK-106 (Tokyo Y.O. After 2 or 3 drops of pendant drop from Chemical Industry Co., Ltd., it was heated in an atmospheric oven at 60° C. for 3 minutes. Then, after drying TOK-106, the appearance of the film was visually confirmed.

The appearance of the film before and after the test was visually observed and evaluated on the following criteria.

○: After the solvent test, the film cannot shrink or swell

△: After the solvent test, the film shrinks or swells slightly

×: After solvent test, film dissolves, or shrinks or swells

[Softness evaluation]

When the obtained film was held by both hands and bent at an acute angle (about 30 degrees), those without cracks were evaluated as ◯, and those with cracks were evaluated as ×.

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

N.D.=Film cracks (film properties cannot be measured)

As shown in Table 1, the resin films obtained from the compositions for forming flexible element substrates of Examples 2 to 11 had high light transmittance [%] at a wavelength of 550 nm, and on the other hand, had a high light transmittance at a wavelength of 308 nm. It becomes less than 5%, and it becomes possible to disclose the application of the laser lift-off method. In addition, the resin film has a reduced yellowness (CIEb ^* ), and the thickness direction retardation R _th is 404 nm or less, the in-plane retardation R ₀ is extremely low, and the birefringence Δn is less than 0.015. value. Moreover, as shown in Table 2, the linear expansion coefficient [ppm/°C] (30 to 220°C) of the resin film was low (less than 31 ppm/°C), heat resistance was improved, and flexibility was obtained. Furthermore, in Examples 8 to 10, the results of solvent resistance to solvents were obtained.

On the other hand, although the resin film of Disclosure Example 1 has the same heat resistance and optical properties as Examples 2 to 11, the light transmittance at a wavelength of 308 nm is increased to 66.5%, and the peeling of the resin film from the base material, The application of the laser lift-off method has had difficult results.

[Peeling of resin film by LLO method]

The composition for forming a flexible element substrate obtained in Example 1 and Example 11 was coated on a glass substrate, and the coating film was exposed to the atmosphere at 50°C for 30 minutes, 140°C for 30 minutes, 200°C for 60 minutes, and then at -99kpa. The resin film was obtained by sequentially heating at 280° C. for 60 minutes under vacuum.

It was evaluated whether the resin film prepared above was peeled off by the LLO method.

However, the following conditions are adopted as the LLO system.

Laser light source: maximum laser XeCl (308nm)

Energy density: 420mJ/cm ² , 500mJ/cm ² , 515mJ/cm ² , 530mJ/cm ² , 560mJ/cm ² , 630mJ/cm ²

Stage movement speed: 7.8mm/sec

Laser beam size: 14mm x 1.3mm (size at maximum energy: 7.8mm x 1.3mm), the repeated scanning range of the laser beam is 80%

The results are shown in Table 3.

In addition, in the table, ○ indicates that the resin film was peeled off, Δ indicates that there is a partial defect in the table, and × indicates that the resin film was not peeled off.

As shown in Table 3, it was confirmed that the resin film of the present invention shown in Example 11 could be peeled off by the LLO method. On the other hand, the resin film of Example 1 not containing TiO ₂ did not peel off under the same conditions.

In this way, the composition for forming a flexible element substrate of the present invention has the characteristics of low linear expansion coefficient, high transparency (high light transmittance, low yellowness), and low retardation, and can also impart excellent solvent resistance, That is, it is possible to form a material of a resin film that satisfies the requirements required as a base film of a flexible element substrate. In particular, this resin film fully absorbs light of a specific wavelength (308 nm), making it possible to apply a laser lift-off method, leading to mass production of flexible devices, and can be expected to be particularly suitable as a base film for flexible device substrates. use.

Claims (10)

A composition for forming a flexible element substrate, comprising: a polyimide having an alicyclic skeleton in its main chain, titanium dioxide particles having a particle diameter of 3 nm to 20 nm, and a ratio measured by a nitrogen adsorption method. Silica particles having an average particle diameter calculated from the surface area value of 100 nm or less, and an organic solvent, wherein the titanium dioxide particles are 3 mass % relative to the total mass of the polyimide, the titanium dioxide particles, and the silicon dioxide particles The mass ratio of the polyimide to the silica particles is 7:3 to 3:7 in an amount of more than 16 mass % or less. The composition for forming a flexible element substrate according to claim 1, wherein the titanium dioxide particles are 0.1 mass % or more and 20 mass % or less with respect to the total mass of the polyimide, the titanium dioxide particles, and the silicon dioxide particles. quantity. The composition for forming a flexible element substrate according to claim 1, further comprising a cross-linking agent, the cross-linking agent being composed of a compound consisting of only hydrogen atoms, carbon atoms, nitrogen atoms and oxygen atoms It has two or more groups selected from the group consisting of a hydroxyl group, an epoxy group, and an alkoxy group having 1 to 5 carbon atoms, and has a cyclic structure. The composition for forming a flexible element substrate according to any one of Claims 1 to 3, wherein the polyimide is a combination of a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a composition containing Fluorine-containing aromatic diamine The polyimide obtained by the imidization of the polyimide obtained by the reaction was divided into two parts. The composition for forming a flexible element substrate according to claim 4, wherein the alicyclic tetracarboxylic dianhydride system comprises the 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 Rs independently represent a hydrogen atom or a methyl group, and * represents a bond)]. The composition for forming a flexible element substrate according to claim 4, wherein the fluorine-containing aromatic diamine comprises a diamine represented by the formula (A1), H ₂ NB ² -NH ₂ (A1) (wherein, B ² represents a divalent base selected from the group consisting of formulas (Y-1)~(Y-34);

(In the formula, * represents a bond portion). The composition for forming a flexible element substrate according to any one of Claims 1 to 3, wherein the silicon dioxide particles have an average particle diameter of 60 nm or less. The composition for forming a substrate for a flexible element according to any one of Claims 1 to 3, which is a composition for forming a substrate for a flexible element to which a laser lift-off method is applied. A flexible element substrate formed of the composition for forming a flexible element substrate according to any one of Claims 1 to 8. A method for manufacturing a flexible element substrate, comprising: applying the composition for forming a flexible element substrate according to any one of claim 1 to claim 8 on a base material, drying and heating to form a flexible element substrate. A step of peeling off the flexible element substrate from the substrate by a laser lift-off method.