TWI754619B - Composition for forming resin thin film - Google Patents

Abstract

An object of the present invention is to provide a composition for forming a resin film, which can impart not only excellent heat resistance and solvent resistance but also a resin film with a feature of low retardation, which is particularly suitable as a substrate for flexible devices resin film.

A composition for forming a resin film comprising polyimide, silica particles, a crosslinking agent and an organic solvent, the silica particles being an average particle size calculated from a specific surface area value measured by a nitrogen gas adsorption method A diameter of 100 nm or less, and a resin film formed from the composition for forming a resin film.

Description

Composition for resin film formation

The present invention relates to a composition for forming a resin film, more specifically, a composition for forming a resin film suitable for display substrate applications such as flexible display substrates.

In recent years, with the rapid development of electronic components (electronics) such as liquid crystal displays and organic electroluminescence displays, thinning and weight reduction of devices, and further flexibility, have become required.

In these devices, various electronic components, such as thin film transistors or transparent electrodes, are formed on a glass substrate. Flexibility. Then, as a candidate for such a resin material, polyimide has been attracting attention, and there have been various reports on polyimide films in the past (for example, refer to Patent Documents 1 and 2).

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 60-188427

[Patent Document 2] Japanese Patent Laid-Open No. 58-208322

[Patent Document 3] Japanese Patent Laid-Open No. 2015-63655

[Patent Document 4] International Publication No. 2011/149018

[Patent Document 5] US Patent Application Publication No. 2011/130495

[Patent Document 6] International Publication No. 2012/129422

However, when a polyimide resin material is used as a substrate of a display, not only is the resin material required to be excellent in transparency or flexibility, but one of the required properties is a material with low retardation, and it is also required to have low retardation. so requested. In addition, when other components are provided on the substrate in the manufacturing process of the display, it may be exposed to the solvent, so the solvent resistance is also required for the polyimide resin material for the substrate (Patent Document 1). 3).

Furthermore, the so-called retardation (retardation) refers to the product of birefringence (the difference between two orthogonal refractive indices) and the film thickness, but this value, especially the retardation in the thickness direction, is important for affecting the viewing angle characteristics. value of . It is known that a large delay value may be a cause of deterioration of the display quality of the display (refer to, for example, Patent Document 4).

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a composition for forming a resin film capable of imparting not only heat resistance It has excellent flexibility, low retardation, excellent transparency, and solvent resistance. Excellent performance resin film.

In the present invention, as a result of repeated and in-depth research in order to achieve the above-mentioned object, it was found that a resin film prepared by blending silicon dioxide and a cross-linking agent in polyimide has excellent heat resistance, low retardation, and also has so-called flexibility. and solvent resistance are excellent; and, by setting the amount of the silica to be formulated in a specified range, a resin excellent in heat resistance, low retardation, excellent flexibility, and furthermore excellent in transparency can be realized film, and the present invention was completed.

Furthermore, Patent Documents 5 and 6 disclose compositions containing a crosslinking agent. However, Patent Documents 5 and 6 do not describe teaching contents about specific effects that can be obtained by the constitution of the present invention, nor do they disclose such contents.

That is, as a first aspect of the present invention, it relates to a composition for forming a resin film comprising a polyimide, silica particles, a crosslinking agent, and an organic solvent, the silica particles being prepared from a The average particle size calculated from the specific surface area value measured by the adsorption method is 100 nm or less, and the crosslinking agent is a compound composed only of hydrogen atoms, carbon atoms, nitrogen atoms and oxygen atoms, and has 2 or more selected from the group consisting of hydroxyl groups, epoxy groups and a group of alkoxy groups with 1 to 5 carbon atoms, and a compound with a cyclic structure.

As a second aspect, the composition for forming a resin film according to the first aspect, wherein the polyimide-based tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a fluorine-containing aromatic A polyimide obtained by reacting a diamine component of a family of diamines and imidizing the obtained polyamide acid.

[式中，B¹表示由式(X-1)~(X-12)所成之群所選出的四價基，

(式中，複數個R相互獨立表示氫原子或甲基，＊表示鍵結鍵)]。 As a third aspect, the composition for forming a resin film according to the second aspect, wherein the alicyclic tetracarboxylic dianhydride includes the tetracarboxylic dianhydride represented by the formula (C1),

[In the formula, B ¹ represents a tetravalent group selected from the group formed by the formula (X-1)~(X-12),

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

As a fourth aspect, the composition for forming a resin film according to the second aspect or the third aspect, wherein the fluorine-containing aromatic diamine includes a 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 of formulas (Y-1) to (Y-34)),

(式中，＊表示鍵結鍵)。

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

As a fifth aspect, the composition for forming a resin film according to any one of the first aspect to the fourth aspect, wherein the mass ratio of the polyimide to the silica particles is 7:3 to 3:7 .

As the sixth viewpoint, any one of the aforementioned first viewpoint to fifth viewpoint The composition for forming a resin film according to the item, wherein the average particle diameter of the silica particles is 60 nm or less.

A seventh aspect relates to a resin film formed from the composition for forming a resin film according to any one of the first to sixth aspects.

The resin film-forming composition according to the present invention can reproducibly form a resin film having a low coefficient of linear expansion, excellent heat resistance, high transparency and low retardation, and excellent flexibility and solvent resistance.

In addition, since the resin film according to the present invention exhibits a low coefficient of linear expansion, high transparency (high light transmittance, low yellowness), and low retardation, and furthermore is excellent in flexibility and solvent resistance, it can be suitably used as a flexible It is used as a substrate of a device (especially a flexible display).

In this way, the composition for forming a resin film and the resin film according to the present invention can sufficiently respond to the requirements of high flexibility, low coefficient of linear expansion, high transparency (high light transmittance, low yellowness), low retardation, and the like. Progress in the field of flexible device substrates (especially flexible display substrates) with specific characteristics.

[The best form of implementing the invention]

Hereinafter, the present invention will be described in detail.

The resin film-forming composition of the present invention contains the following specific polyimide, silica particles, a crosslinking agent, and an organic solvent.

[Polyimide]

The polyimide type used in the present invention is preferably a polyamide acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a diamine component containing a fluorine-containing aromatic diamine Polyimide obtained by imidization.

Among them, the aforementioned alicyclic tetracarboxylic dianhydride preferably includes a tetracarboxylic dianhydride represented by the following formula (C1); the aforementioned fluorine-containing aromatic diamine preferably includes the following formula (A1) ) represented by the diamine.

[式中，B¹係表示由式(X-1)~(X-12)所成之群所選出的四價基。

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

(式中，複數個R相互獨立表示氫原子或甲基，＊表示鍵 結鍵)]。

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

[Chemical 11] H ₂ NB ² -NH ₂ (A1) (wherein, B ² represents a divalent group selected from the group of formulae (Y-1) to (Y-34)).

(式中，＊表示鍵結鍵)。

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

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

Moreover, among the diamines represented by the above (A1), B ² in the formula is preferably a compound represented by the formulae (Y-12) and (Y-13).

A suitable example is a polyamide obtained by reacting a tetracarboxylic dianhydride represented by the above formula (C1) with a diamine represented by the above formula (A1), and imidizing the obtained polyamide acid. The imine contains a monomer unit represented by the following formula (2).

In order to obtain a resin film having the characteristics of low linear expansion coefficient, low retardation, and high transparency, which are the objects of the present invention, and excellent in flexibility, alicyclic tetracarboxylic The acid dianhydride such as the tetracarboxylic dianhydride represented by the above formula (C1) is preferably more than 90 mol%, more preferably 95 mol% or more, especially the whole (100 mol%) is the above formula The tetracarboxylic dianhydride represented by (C1) is the most suitable.

Also, in order to obtain a resin film having the above-mentioned characteristics of low linear expansion coefficient, low retardation and high transparency, and excellent flexibility, a fluorine-containing aromatic diamine such as the formula ( The diamine represented by A1) is preferably more than 90 mol%, and more preferably 95 mol% or more. Moreover, the diamine represented by the said formula (A1) may be all (100 mol%) of diamine components.

As an example of a suitable aspect, the polyimide type|system|group used by this invention contains the monomer unit represented by 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 of the present invention is composed of an alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the aforementioned formula (C1), and a diamine containing the diamine represented by the 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 can be arbitrarily determined within a range that does not impair the properties of the resin film formed from the composition for forming a resin film of the present invention. This ratio is relative to the alicyclic tetracarboxylic acid containing the tetracarboxylic dianhydride represented by the aforementioned formula (C1). The total number of moles of monomer units derived from the dianhydride component and the diamine component containing the diamine represented by the formula (A1) is preferably less than 20 mol %, and less than 10 mol %. More preferably, less than 5 mol % is still more preferable.

Such other monomer units include, for example, monomer units having other polyimide structures represented by formula (3), but are not limited thereto.

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 one of Formulas (B-1)-(B-11). In each formula, * represents a bond bond. Still, in formula (3), if A is a tetravalent group represented by any one of the following formulas (A-1) to (A-4), B may also be the aforementioned formula (Y-1) to The divalent group represented by any one of (Y-34). Or in formula (3), when B is a divalent group represented by any one of the following formulae (B-1) to (B-11), A may also be the aforementioned formula (X-1) to ( The tetravalent group represented by any one of X-12).

When the polyimide of the present invention contains the monomer unit represented by the formula (3), A and B may contain, for example, only a monomer unit composed of only one of the groups exemplified by the following formula, A At least one of B and 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 bonded in an arbitrary order.

In addition, the polyimide used in the present invention is composed of an alicyclic tetracarboxylic dianhydride containing the tetracarboxylic dianhydride represented by the aforementioned formula (C1). In addition to the monomer unit derived from the diamine component containing the diamine represented by the formula (A1), if there is another monomer unit represented by the above formula (3), the polyamide containing each monomer unit The imine is obtained by combining a tetracarboxylic dianhydride represented by the following formula (5) other than the tetracarboxylic dianhydride represented by the above formula (C1) as a tetracarboxylic dianhydride component, and a diamine component The diamine represented by the following formula (6) other than the diamine represented by the above (A1) is obtained by polymerizing in an organic solvent and imidizing the obtained polyamide.

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 tetracarboxylic acid Carboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, 11,11-bis(trifluoromethyl)-1H-difluoro[3,4-b:3 ',4'-i]Dibenzopyran-1,3,7,9-(11H-tetraone), 6,6'-bis(trifluoromethyl)-[5,5'-diisophenyl furan]-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']di Furan-1,3,5,7-tetraone, N,N'-[2,2'-bis(trifluoromethyl)biphenyl-4,4'-diyl]bis(1,3-diyl) Aromatic tetracarboxylic acids such as oxygen-1,3-dihydroisobenzofuran-5-carboxamide); 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid anhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1, Alicyclic tetracarboxylic dianhydride such as 2,3,4-cyclohexanetetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, etc. ; Aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butane tetracarboxylic dianhydride, etc., but not limited to these.

Among these, A in the formula (5) is preferably a tetravalent tetracarboxylic dianhydride represented by any one of the aforementioned formulas (A-1) to (A-4), that is, for example 11,11-Bis(trifluoromethyl)-1H-difluoro[3,4-b:3',4'-i]dibenzopyran-1,3,7,9-(11H-tetraone ), 6,6'-bis(trifluoromethyl)-[5,5'-diisobenzofuran]-1,1',3,3'-tetraone, 4,6,10,12-tetrakis Fluorodifuro[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 is a preferred compound.

Moreover, as the diamine represented by 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)bis Aniline, 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-methylbenzidine , 3-methylbenzidine, 2-(trifluoromethyl)benzidine, 3-(trifluoromethyl)benzidine, 2,2'-dimethylbenzidine (m-benzidine), 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'-difluoro Benzidine, 3,3'-difluorobenzidine, 2,3'-difluorobenzidine, 2,2'-dichlorobenzidine, 3,3'-dichlorobenzidine, 2,3'-dichlorobenzidine Benzidine, 4,4'-diaminobenzylaniline, 4-aminophenyl-4'-aminobenzoate, octafluorobenzidine, 2,2',5,5'-tetramethyl benzidine, 3,3',5,5'-tetramethylbenzidine, 2,2',5,5'-tetra(trifluoromethyl)benzidine, 3,3',5,5'- Four (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"-bitriphenyl)-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 and other aromatic diamines; 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(3-methylcyclohexylamine), isophoronediamine, trans-1,4-cyclohexanedi Amine, 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-propanediamine, 1,4-tetramethylenediamine, 1,5-Pentamethylene Aliphatic diamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, etc. Diamines, but not limited to these.

Among these, B in the formula (6) is preferably a divalent aromatic diamine represented by any one of the aforementioned formulas (B-1) to (B-11), such as 2, 2'-bis(trifluoromethoxy)-(1,1'-biphenyl)-4,4'-diamine [alias: 2,2'-dimethoxybenzidine], 4,4'- (Perfluoropropane-2,2-diyl)dianiline, 2,5-bis(trifluoromethyl)benzene-1,4-diamine, 2-(trifluoromethyl)benzene-1,4-diamine Amine, 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"-triphenyl)-4,4"-diyl]-bis(oxygen) base)}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 is a preferred diamine.

<Synthesis of Polyamide>

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

The conversion reaction from the above two components to polyamic acid is advantageous in that it can be carried out relatively easily in an organic solvent, and by-products are not generated.

In the reaction between these tetracarboxylic dianhydride components and the diamine component, the position of the diamine component can be appropriately set in consideration of the molecular weight of the polyamic acid and the polyimide obtained by subsequent imidization. The ratio (molar ratio) of the tetracarboxylic dianhydride component relative to the diamine component 1 is usually about 0.8 to 1.2, for example, about 0.9 to 1.1, preferably about 0.95 to 1.02. As in the general polycondensation reaction, as the molar ratio is closer to 1.0, the molecular weight of the produced polyamic acid becomes larger.

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 can dissolve the produced polyamide. This specific example is illustrated 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 Amine, 3-Propoxy-N,N-Dimethylpropionamide, 3-Isopropoxy-N,N-Dimethylpropionamide, 3-Butoxy-N,N-Dimethyl Propionamide, 3-sec-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, γ-butyrolactone, N- Methyl caprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfoxide, isopropanol, methoxymethyl pentanol, dipentene, ethyl amyl ketone, methyl nonyl methyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cylosu base carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, Propylene Glycol Monomethyl Ether, Propylene Glycol-tert-Butyl Ether, Dipropylene Glycol Monomethyl Ether, Diethylene Glycol, Diethylene Glycol Monoacetate, Diethylene Glycol Dimethyl Ether, Dipropylene Glycol Monoacetate Monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3- Methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, acetic acid Amyl ester, butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, propyl ether, dihexyl ether, dioxane, n-hexane, n-pentane, n-octane, Diethyl ether, cyclohexanone, ethylidene carbonate, propylidene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl anhydride, propylene glycol monoethyl ether acetate, pyruvic acid methyl ester, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3- Methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, diethylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, etc., but Not limited to these. These may be used alone or in combination of two or more.

Furthermore, even if it is a solvent incapable of dissolving polyamic acid, as long as it is a range in which the produced polyamic acid does not precipitate, you may mix and use it with the said solvent. In addition, the moisture in the organic solvent not only inhibits the polymerization reaction, but also causes the hydrolysis of the produced polyamic acid. Therefore, it is preferable to use an organic solvent that has been dehydrated and dried as much as possible.

As a method of reacting the above-mentioned tetracarboxylic dianhydride component and diamine component in an organic solvent, a method of dispersing or dissolving the diamine component in an organic solvent by stirring to obtain a dispersion or solution, A method of directly adding a tetracarboxylic dianhydride component to a liquid or solution, or adding an organic solvent to disperse or dissolve the tetracarboxylic dianhydride component; on the contrary, to disperse or dissolve the tetracarboxylic dianhydride component in an organic solvent The method of adding the diamine component to the dispersion liquid or solution of the above; the method of adding the tetracarboxylic dianhydride component and the diamine compound component alternately, etc., any of these methods can be used.

Moreover, when the tetracarboxylic dianhydride component and/or the diamine component are composed of a plurality of compounds, they may be reacted in a state of being mixed in advance, or may be reacted in sequence separately, and further The low-molecular-weight body obtained by the direct reaction is mixed and reacted to obtain a high-molecular-weight body.

The temperature during the synthesis of the above-mentioned polyamic acid should be appropriately set within the range from the melting point to the boiling point of the solvent used above. °C is 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 determined uniformly, but is usually about 1 to 100 hours.

In addition, the reaction can be carried out at any concentration. If the concentration is too low, it will be difficult to obtain a polymer with high molecular weight; if the concentration is too high, the viscosity of the reaction solution will become too high and it will be difficult to stir uniformly. The total concentration in the reaction solution of the acid dianhydride component and the diamine component is preferably 1 to 50% by mass, and more preferably 5 to 40% by mass. It is also possible to carry out the reaction at a high concentration in the initial stage, and then add an organic solvent.

<Imidation of Polyamides>

As a method of imidizing the polyamide, direct heating of the polyamide can be exemplified. Thermal imidization of a solution of aramidic acid and catalytic imidization of a solution of polyamide acid by adding a catalyst.

When thermal imidization of the polyamic acid in the solution is performed, the temperature is 100°C to 400°C, preferably 120°C to 250°C, so as to discharge the water generated by the imidization reaction to the outside of the system, Simultaneous imidization is preferably performed.

The chemical (catalyst) imidization of polyamic acid can be carried out by adding alkaline catalyst and acid anhydride to the solution of polyamic acid at -20~250℃, preferably 0~180℃. It is carried out by stirring in the system under temperature conditions.

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

Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, 1-ethylpiperidine, and the like, wherein pyridine has an appropriate amount for the reaction to proceed. Alkaline, so it is better.

Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic dianhydride, and the like. Among them, when acetic anhydride is used, purification after the completion of the reaction is easy, and is therefore preferred.

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

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

In the present invention, after filtering the above-mentioned reaction solution, the filtrate can be used directly, or it can also be diluted or concentrated, and the preparation will be described later. Silicon dioxide or the like makes it a composition for forming a resin film. Through filtration in this way, not only can the contamination of impurities (which 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 resin film can be efficiently obtained. thing.

The polyimide used in the present invention is determined in terms of polystyrene 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 obtained weight average molecular weight (Mw) is preferably 5,000 to 200,000.

<Polymer recycling>

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

In addition, if the operation of re-dissolving the polymer recovered by precipitation in an organic solvent and then reprecipitating and recovering is repeated 2 to 10 times, impurities in the polymer can be reduced. As the weak solvent at this time, it is preferable to use three or more types of weak solvents, such as alcohols, ketones, and hydrocarbons, because the efficiency of purification can be further improved.

In the reprecipitation recovery step, the organic solvent for dissolving the resin component is not particularly limited. Specific examples include N,N-dimethylformamide Amine, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinyl pyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfoxide, gamma-butyrolactone, 1,3-dimethyl-imidazolidinone, dipentene, ethyl amyl ketone , methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propyl carbonate, diethylene glycol dimethyl ether, 4 -Hydroxy-4-methyl-2-pentanone, etc. These solvents may be used by mixing two or more types.

[Silicon dioxide]

The silica (silica) used in the present invention is not particularly limited, and silica in particle form, for example, with an average particle diameter of 100 nm or less, for example, 5 nm to 100 nm, preferably 5 nm to 55 nm, can be obtained with good reproducibility. From the viewpoint of a higher transparent film, it is preferably 5 nm to 50 nm, more preferably 5 nm to 45 nm, more preferably 5 nm to 35 nm, and still more preferably 5 nm to 30 nm.

The average particle diameter of the silica particles in the present invention is the average particle diameter value calculated from the specific surface area value measured by the nitrogen gas adsorption method using the silica particles.

In particular, colloidal silica having the above-mentioned average particle diameter can be suitably used in the present invention, and as the colloidal silica, a silica sol can be used. As the silica sol, an aqueous silica sol produced by a known method using an aqueous sodium silicate solution as a raw material, and an organosilica sol obtained by replacing the water as a dispersing medium of the aqueous silica sol with an organic solvent can be used. glue.

In addition, alkoxysilanes such as methyl silicate or ethyl silicate can also be used in organic solvents such as alcohols and in catalysts (such as ammonia, organic amine compounds, alkali catalysts such as sodium hydroxide, etc.). A silica sol obtained by hydrolysis and condensation in the presence of the silica sol, or an organosilica sol obtained by substituting the silica sol with another organic solvent.

Among these, in the present invention, it is preferable to use an organosilicon sol in which the dispersing medium is an organic solvent.

As examples of the organic solvent in the above-mentioned organosilicon sol, lower alcohols such as methanol, ethanol, isopropanol, etc.; N,N-dimethylformamide, N,N-dimethylacetamide Linear amides such as N-methyl-2-pyrrolidone; cyclic amides such as N-methyl-2-pyrrolidone; ethers such as γ-butyrolactone; diols such as ethyl cylosoline and ethylene glycol , acetonitrile, etc. The substitution can be carried out by ordinary methods such as distillation and ultrafiltration.

The viscosity of the above-mentioned organosilicon sol is about 0.6mPa·s~100mPa·s at 20℃.

Examples of commercial products of the above-mentioned organosilica sol include trade name MA-ST-S (methanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name MT-ST (methanol-dispersed silica sol), and trade name. , 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 silica sol, Nissan Chemical Industry Co., Ltd.) (stock), trade name MA-ST-L (methanol-dispersed silica sol, Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-S (isopropanol-dispersed silica sol, Nissan Chemical Industry (stock) ), trade name IPA-ST (isopropyl alcohol Dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-UP (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-L (isopropyl alcohol) Dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-ZL (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name NPC-ST-30 (n-propane Kisailuosu 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, Nissan Chemical Industry Co., Ltd.) made), trade name EAC-ST (ethyl acetate dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name PMA-ST (propylene glycol monomethyl ether acetate dispersed silica sol, Nissan Chemical Industry Co., Ltd. ), trade name MEK-ST (Methyl Ethyl Ketone Dispersed Silica Sol, Nissan Chemical Industry Co., Ltd.), trade name MEK-ST-UP (Methyl Ethyl Ketone Dispersed Silica Sol, Nissan Chemical Industry Co., Ltd.) (stock), trade name MEK-ST-L (methyl ethyl ketone disperse silica sol, Nissan Chemical Industry Co., Ltd.) and trade name MIBK-ST (methyl isobutyl ketone disperse silica sol, Nissan Chemical industry (stock) system), etc., but not limited to these.

The silica in the present invention may be used as, for example, an organosilicon sol, and may be used as a mixture of two or more of the above-mentioned products.

[Crosslinking agent]

The crosslinking agent used in the present invention is composed of only hydrogen atoms, carbon atoms and nitrogen atoms. A compound composed of a proton and an oxygen atom and having 2 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 a crosslinking agent composed of a compound having a ring structure . Here, "consisting only of hydrogen atoms, carbon atoms, nitrogen atoms, and oxygen atoms" means consisting of only atoms selected from the group of the above-mentioned four atoms, that is, not only including the above-mentioned four atoms All and only of these atoms may be composed of only 3 of the above-mentioned 4 atoms (for example, a hydrogen atom, a carbon atom, an oxygen atom, etc.). By using such a crosslinking agent, not only a resin film excellent in solvent resistance can be obtained with good reproducibility, but also a resin composition with further improved storage stability can be realized.

Among them, the total number of hydroxyl groups, epoxy groups, and alkoxy groups having 1 to 5 carbon atoms in each compound in the crosslinking agent is from the viewpoint of realizing the solvent resistance of the obtained resin film with good reproducibility. , is preferably 3 or more, and is preferably 10 or less, more preferably 8 or less, still more preferably 6 or less, from the viewpoint of achieving good reproducibility and flexibility of the obtained resin film.

、1,3,5-三嗪等之含氮原子雜芳基環、環戊烷、環己烷、環庚烷等之環烷烴環、哌啶、哌嗪、六氫嘧啶、六氫嗒

、六氫-1,3,5-三嗪等之環狀胺等。 Specific examples of the ring structure of the crosslinking agent include aryl rings such as benzene, pyridine, pyrazine, pyrimidine, pyridine, etc.

, 1,3,5-triazine and other nitrogen-containing heteroaryl rings, cyclopentane, cyclohexane, cycloheptane and other cycloalkane rings, piperidine, piperazine, hexahydropyrimidine, hexahydropyridine

, cyclic amines such as hexahydro-1,3,5-triazine, etc.

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

In addition, if there are 2 or more ring structures, the ring structures can be condensed with each other, and the number of carbon atoms such as methylene, ethylidene, triphenylene, and propane-2,2-diyl can be 1~5. A linking group such as an alkane-diyl group is used to bond the ring structures to each other.

The molecular weight of the cross-linking agent is not particularly limited as long as it has cross-linking ability and can be dissolved in the solvent used, but the solvent resistance of the obtained resin film and the solubility of the cross-linking agent itself in organic solvents are considered. , In terms of availability or price, it is preferably about 100 to 500, and 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), etc., a hydrogen atom, a carbon atom, a nitrogen atom, and an oxygen atom.

As a cross-linking agent, as a preferred example, the compounds represented by the following formulae (K1) to (K5) can be exemplified, respectively as one of the preferred forms of the formula (K4), and the compounds represented by the formula (K4-1) can be exemplified respectively. The compound represented by the formula (K5) can be exemplified by the compound represented by the formula (5-1).

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

Each X series independently represents hydroxyl, epoxy (oxa-cyclopropyl), or methoxy, ethoxy, 1-propoxy, isopropoxy, 1-butoxy, t-butoxy Alkoxy groups having 1 to 5 carbon atoms such as radicals.

Among them, considering the availability and price of the cross-linking agent, epoxy groups are preferred in the X-series formulas (K1) and (K5), and 1 to 1 to carbon atoms are preferred in the formulas (K2) and (K3). The alkoxy group of 5 is preferred, and the hydroxyl group in formula (K4) is preferred.

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

In each compound, it is preferable that all A ¹ series are the same group, and each X series is preferably all the same group.

The compounds represented by the above formulae (K1) to (K5) can be obtained by combining aryl compounds, heteroaryl compounds, and cyclic amines having the same ring structure as those in these compounds. The skeleton compound, etc., with epoxy alkyl halide compound, alkoxy halide compound, etc., undergo carbon-carbon coupling reaction or N-alkylation reaction, or hydrolyze the alkoxy group of the product.

As a crosslinking agent, a commercial item may be used, and what was synthesize|combined by a well-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 XW 3106, the same MM-100, the same 323, the same 325, the same 327, Same as 328, same as 385, same as 370, same as 373, same as 380, same as 1116, same as 1130, same as 1133, same as 1141, same as 1161, same as 1168, same as 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 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-227-8, same as U-1050-10, same as U-1050-10 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 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 U1-27-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. , Same as PAS, Same as VL, Same as UC (above, Nissan Chemical Industry Co., Ltd.), TM-BIP-A (Asahi Organic Materials Industry Co., Ltd.), 1,3,4,6-4 (Methoxy Methyl)acetylene carbamide (hereinafter abbreviated as TMG) (manufactured by Tokyo Chemical Industry Co., Ltd.), 4,4'-methylenebis(N,N-diglycidylaniline) (manufactured by Aldrich Corporation), and the like.

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

The mixing ratio of the crosslinking agent is 0.1 to 200 mass %, preferably 0.2 to 100 mass %, with respect to the total mass of the polyimide and the silicon dioxide.

[Organic solvents]

The resin film-forming composition of the present invention may contain an organic solvent in addition to the aforementioned polyimide and silica. Although this organic solvent is not specifically limited, For example, it is the same as the specific example of the reaction solvent used for the preparation of the said polyamic acid and polyimide. More specifically, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2- Imidazolidinone, N-ethyl-2-pyrrolidone, γ-butyrolactone, etc. In addition, an organic solvent system may be used individually by 1 type, and may be used in combination of 2 or more types.

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

[Composition for resin film formation]

The present invention is a composition for forming a resin film containing the aforementioned polyimide, silica and an organic solvent. Here, the composition for forming a resin film of the present invention is uniform and phase separation is not confirmed.

In the composition for forming a resin film of the present invention, the blending ratio of the aforementioned polyimide and the aforementioned silicon dioxide is preferably polyimide:silicon dioxide=10:1~1:10 in terms of mass ratio. Preferably it is 8:2~2:8, for example, 7:3~3:7.

In the composition for forming a resin film of the present invention, the mixing ratio of the crosslinking agent relative to the total mass of the polyimide and the silicon dioxide is: 0.1 to 200 mass %, preferably 0.2 to 100 mass %.

Moreover, the compounding quantity of the solid content in the composition for resin film formation of this invention is about 0.5-30 mass % normally, Preferably it is about 5-25 mass %. If the solid content concentration is less than 0.5 mass %, the film-forming efficiency in the production of the resin film will be low, and the viscosity of the resin film-forming composition will be low, making it difficult to obtain a uniform coating film on the surface. Moreover, when the solid content concentration exceeds 30 mass %, the viscosity of the composition for resin film formation will become too high, and there exists a possibility that film-forming efficiency may deteriorate or the surface uniformity of a coating film may be lacking. Incidentally, the solid content as used herein means the total mass of components other than the organic solvent, and even liquid monomers are included in the weight as solids.

In addition, the viscosity of the composition for forming a resin film is appropriately set in consideration of the thickness of the resin film to be produced, etc. In particular, if the purpose of obtaining a resin film with a thickness of about 5 to 50 μm with good reproducibility is especially, it is usually 25 μm. At ℃, it is about 500~50,000mPa·s, preferably about 1,000~20,000mPa·s.

Various other organic or inorganic low-molecular or high-molecular compounds may be blended in the composition for forming a resin film of the present invention in order to impart processing properties and various functionalities. 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. Furthermore, in addition to the aforementioned polyimide, silica, and organic solvent, a composition for forming a resin thin film that further includes a catalyst can also be set as the object of the present invention.

The composition for forming a resin film of the present invention can be obtained by dissolving the polyimide and silica obtained by the above-mentioned method in the above-mentioned organic solvent, or by adding silica to the polyimide It can be obtained by further adding the above-mentioned organic solvent to the reaction solution after the preparation of the amine as desired.

[resin film]

By applying the above-described composition for forming a resin film of the present invention to a substrate, drying and heating, and removing the organic solvent, it is possible to obtain high heat resistance, high transparency, moderate flexibility, and A moderate coefficient of linear expansion, and the retardation is a small resin film.

Then, the above-mentioned resin film, that is, the resin film containing the above-mentioned polyimide and the above-mentioned inorganic silica compound is also the object of the present invention. Furthermore, in addition to the aforementioned polyimide and silica, a resin film further including a catalyst is also the object of the present invention.

As the base material used in the production of the resin film, for example, plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetate cellulose, ABS, AS, norbornene-based resin, etc.), metal, stainless steel (SUS), wood, paper, glass, silicon wafer, slate, etc.

In particular, when it is applied as a substrate material for electronic devices, from the viewpoint of utilizing existing equipment, the applicable substrates are preferably glass and silicon wafers. Moreover, since the obtained resin film is used as a display material. Good peelability, so glass is better. still, as the linear expansion system of the applicable substrate From the viewpoint of the warpage of the substrate after coating, it is preferably 30 ppm/°C or lower, and more preferably 20 ppm/°C or lower.

The method for coating the substrate with the composition for forming a resin film is not particularly limited, and examples include cast coating, spin coating, blade coating, dip coating, roll coating, and bar coating. A cloth method, a die coating method, an ink jet method, a printing method (relief, gravure, lithography, screen printing, etc.) and the like can be appropriately used according to the purpose.

The heating temperature is preferably 300°C or lower. When it exceeds 300 degreeC, the obtained resin film may become brittle, and the resin film suitable for a display board|substrate application especially may not be obtained.

In addition, considering the heat resistance and linear expansion coefficient characteristics of the obtained resin film, after heating the coated composition for forming a resin film at 40° C. to 100° C. for 5 minutes to 2 hours, it is directly applied in stages. The heating temperature rises, and it is preferable that the temperature finally exceeds 175°C to 280°C and heating is performed for 30 minutes to 2 hours. In this way, it is possible to exhibit low thermal expansion characteristics by heating at a temperature of two or more stages of the stage of drying the solvent and the stage of promoting molecular alignment.

In particular, the coated resin film forming composition is heated at 40°C to 100°C for 5 minutes to 2 hours, then heated at over 100°C to 175°C for 5 minutes to 2 hours, and then heated at over 175°C to 280°C ℃ heating for 5 minutes to 2 hours is preferred.

As 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; also, it can be under normal pressure or under reduced pressure; and, in each stage of heating, it can also be suitable. Use different pressures.

The thickness of the resin film, especially when used as a substrate for a flexible display, is usually about 1 to 60 μm, preferably about 5 to 50 μm, so that the thickness of the coating film before heating can be adjusted to form a resin film of the desired thickness .

The method for peeling the resin film formed in this way from the substrate is not particularly limited, and examples include cooling the resin film together with the substrate, inserting cracks into the film and peeling the film, or applying a roll to the film. A method of pretensioning and peeling it off, etc.

The thus-obtained resin film related to a preferred state of the present invention can achieve so-called high transparency with a light transmittance of 75% or more at a wavelength of 400 nm.

Furthermore, the resin film, for example, has a linear expansion coefficient of 60 ppm/°C or less at 50°C to 200°C, particularly a so-called low value of 10 ppm/°C to 35 ppm/°C, and is excellent in dimensional stability during heating.

In particular, when the wavelength of the incident light is ₅₉₀ nm, the in-plane retardation R ₀ and the thickness-direction retardation R _th are both very small. Represented by the product of the difference between the two orthogonal refractive indices) and the film thickness; the above-mentioned thickness-direction retardation R _th is observed from a cross-section in the thickness direction, for two birefringences (two refractive indices in the plane) The difference between the refractive indices in the thickness direction) is multiplied by the respective film thickness, and the obtained two retardations are expressed as an average value. In the resin film of the present invention, if the average film thickness is about 15 μm to 40 μm, the retardation R _th in the thickness direction is less than 700 nm, such as 300 nm or less, such as 1 nm to 300 nm, and the in-plane retardation R ₀ is less than 4, such as 0.1~ 3.9, the birefringence Δn is less than 0.01, for example, 0.0003 to 0.009 has a so-called very low value.

Since the resin film of the present invention described above has the above-mentioned properties, it can satisfy various conditions required as a base film of a flexible display substrate, and can be suitably used as a base film of a flexible display substrate.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these. Furthermore, the abbreviations of the reagents used, the apparatuses 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)]

Into a 250 mL three-necked reaction flask equipped with a nitrogen injection/discharge port and equipped with a Dean-Stark device and a mechanical stirrer, TFMB 12.8092 g (0.04 mol) and γ-butyrolactone (GBL) 60.85 g were added and stirring was started . After the diamine (TFMB) was completely dissolved in the solvent, BODAxx 5.001 g (0.02 mol) and GBL 13.04 g were added, by heating at 90° C. for 20 minutes under nitrogen atmosphere. After that, 3.922 g (0.02 mol) of CBDA and 13.04 g of GBL (γ-butyrolactone) were added and reacted under nitrogen atmosphere for 20 minutes. 0.87 g (0.0076 mol) of 1-ethylpiperidine was added to the reactant, and the temperature was raised to 180° C. and kept for 7 hours. GBL was added to the reaction mixture to dilute so that the solid content concentration (the concentration of the components excluding the organic solvent) would be 10% by mass. After that, the diluted reaction mixture was added to 760 g of methanol and stirred for 30 minutes, and the filtrate was recovered by filtration. This procedure was repeated 3 times.

Finally, the obtained filtrate was dried in a vacuum oven at 150° C. for 8 hours to obtain 18.77 g of the intended polyimide (I) (yield 86.4%, Mw: 205,321, Mn: 77,087).

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

In a 1000 mL round-bottomed flask, 350 g of methanol-dispersed silica sol: MA-ST-M (silica solid content concentration: 40.4 mass %) and 419 g of γ-butyrolactone manufactured by Nissan Chemical Industry Co., Ltd. were added. Then, the flask was connected to a vacuum evaporator, the inside of the flask was depressurized, and the silica sol in which the solvent was substituted from methanol to γ-butyrolactone was obtained by immersing it in a warm water bath at about 35° C. for 20 to 50 minutes. (GBL-M) about 560.3 g (silica 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 is 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 expressed as D (nm). )=2720/S to calculate the average primary particle size.

[Preparation of composition for resin film formation] [Example 1-1]

At room temperature, 1 g of the powdered polyimide (I) prepared in the synthesis example was dissolved in GBL, and the resulting solution was gradually subjected to pressure filtration using a 5 μm filter to prepare a solid content concentration of 8 mass % solution (polyimide solution (I)). To this polyimide (I) solution, 9.24 g of GBL-M silica sol (concentration of silica solid content: 25.25 mass %) prepared in the preparation example and 1.428 g of Cymel 303 (purity 100%) were added, and The resin film-forming composition can be obtained by stirring overnight.

[Example 1-2]

Obtained in the same manner as in Example 1-1, except that 1,3,4,6-tetra(methoxymethyl)acetylene carbamide (TMG) (purity 99%) 1.442g was used instead of Cymel 303 1.428g A composition for forming a resin film.

[Example 1-3]

A resin was obtained in the same manner as in Example 1-1, except that 3.96 g of GBL-M silica sol and 0.866 g of TEPIC-L (purity 99%) were used instead of 9.24 g of GBL-M silica sol and 1.428 g of Cymel 303 Composition for thin film formation.

[Example 1-4]

A resin film-forming composition was obtained in the same manner as in Example 1-1, except that 0.594 g of Cymel 303 (purity 100%) and 0.0396 g of TM-BIP-A (purity 98%) were used instead of 1.428 g of Cymel 303.

[Comparative Example 1-A]

A composition for forming a resin film was obtained in the same manner as in Example 1-1 except that 1.428 g of Cymel 303 was not used.

[Production of resin film] [Example 2-1]

The resin film-forming composition obtained in Example 1-1 was coated on a glass substrate, and the coating film was sequentially heated at 50° C. for 30 minutes under the atmosphere, followed by: A resin film can be obtained by sequentially heating at 140°C for 30 minutes, 200°C for 60 minutes, and then at 280°C for 60 minutes in a nitrogen atmosphere.

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

[Example 2-2 to Example 2-4, Comparative Example 2-A]

The resin film-forming compositions obtained in Examples 1-2 to 1-4 and Comparative Example 1-A were used instead of the resin film-forming compositions obtained in Example 1-1. Each resin film was obtained by the same method.

[Evaluation of thin films]

The heat resistance and optical properties of each resin film (evaluation sample) produced by the above procedure, namely coefficient of linear expansion (CTE) at 50°C to 200°C, 5% weight reduction temperature (Td _5% ), light transmittance (T _{308 nm} , T _{400 nm} , T _{550 nm} ) and CIE b ^* value (yellow evaluation), retardation (R _th , R ₀ ) and birefringence (Δn) were evaluated according to the following procedures, respectively. The results are shown in Table 1.

1) Coefficient of Linear Expansion (CTE)

Using TMA Q400 manufactured by TA Instruments, the film was cut into a size of 5 mm in width and 16 mm in length. First, the temperature was increased at 10°C/min and heated to 50 to 300°C (first heating), and then the temperature was increased at 10°C/min. After cooling and cooling to 50°C, the temperature was increased at 10°C/min and heated to 50 to 420°C (second heating), by measuring the second heating from 50°C to 50°C. It can be obtained from the value of the coefficient of linear expansion (CTE [ppm/°C]) at 200°C. Furthermore, the whole process of the first heating, cooling and the second heating is an applied load of 0.05N.

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

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

3) Light transmittance (transparency) (T _308nm , T _400nm , T _550nm ) and CIE b value (CIE b ^* )

Light transmittance (T _{308 nm} , T _{400 nm} , T _{550 nm} [%]) and CIE b value (CIE b ^* ) at wavelengths of 308 nm, 400 nm and 550 nm were measured at room temperature using SA4000 spectrometer manufactured by Nippon Denshoku Industries Co., Ltd. The measurement is performed using air as a reference.

4) Delay (R _th , R ₀ )

The thickness direction retardation (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 according to 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 referred to as the slow axis (slow axis), Ny is referred to as the fast axis (fast axis))

Nz: Refractive index in the thickness (vertical) direction (vertical) with respect to the plane

d: film thickness

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

ΔNxz: Difference between the refractive index Nx in the plane and the refractive index Nz in the thickness direction (birefringence)

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

5) Film thickness (d)

The film thickness of the obtained thin film was measured with the thickness gauge made by (stock) Teclock.

6) Birefringence (△n)

Using the value of the retardation (R _th ) in the thickness direction obtained by the above-mentioned <4) retardation>, it was calculated according to the following formula.

△N=[R _th /d(film thickness)]/1000

[Example 3-1]

By immersing the film obtained in Example 2-1 (a rectangular film of 3 cm×3 cm) in a test solvent at 60 to 70° C. for 3 to 5 minutes at room temperature. As a test solvent, TOK106 (manufactured by Tokyo Oka Kogyo Co., Ltd.), NMP, and solvent A (NMP: PGME: deionized water: tetrahydrofurfuryl alcohol=30 mass %: 30 mass %: 20 mass %: 20 mass %) were used , or solvent B (NMP: PGME: deionized water: tetrahydrofurfuryl alcohol=50 mass %: 10 mass %: 20 mass %: 20 mass %).

After the solvent test, the film was washed with deionized water, and the water droplets were allowed to dry in an atmospheric oven at 200°C for 10 minutes.

The film quality was measured before and after this test, and the change rate was calculated and evaluated as a mass reduction [%] (a negative value reflects a mass reduction). again, borrow The appearance of the film before and after this test was visually observed.

[Examples 3-2 to 3-4, Comparative Example 3-A]

Using the thin films obtained in Examples 2-2 to 2-4 and Comparative Example 2-A, the same solvent immersion test as in Example 3-1 was implemented. In addition, in Example 3-3 and Example 3-4, only TOK106 was used as the test solvent to carry out the test.

Table 1 shows the evaluation of the heat resistance and optical properties of the resin films obtained from the respective resin film-forming compositions, and Table 2 shows the results of the solvent immersion test, respectively.

[Table 2]

As shown in Tables 1 and 2, the resin film of the present invention has a low linear expansion coefficient [ppm/°C] (50 to 200°C) (less than 35 ppm/°C) and a high light transmittance [%], Furthermore, the heat resistance was also improved, and the yellowness (CIE b ^* ) was also low. Furthermore, the thickness direction retardation R _th is an extremely low value of less than 300 nm, the birefringence Δn is also an extremely low value of less than 0.01, and it has solvent resistance to various solvents.

On the other hand, the resin film of the comparative example had the same heat resistance and optical properties as the examples, but the solvent resistance was poor.

In this way, the resin film of the composition for forming a resin film of the present invention produced by using diamine has a low coefficient of linear expansion, high transparency (high light transmittance, low yellowness), low retardation, and excellent solvent resistance. characteristics, which can satisfy the necessary base film for flexible display substrates Therefore, it is expected to be particularly suitable for use as a base film of a flexible display substrate.

Claims (3)

A composition for forming a resin film comprising polyimide, silica particles, a crosslinking agent, and an organic solvent, wherein the polyimide contains an alicyclic tetramine represented by the following formula (C1). The tetracarboxylic dianhydride component of the carboxylic dianhydride and the diamine component containing the fluorine-containing aromatic diamine represented by the following formula (A1) are reacted, and the obtained polyamic acid imidization is obtained. The polyimide, and contains the monomer unit represented by the following formula (2), the silica particles have an average particle diameter of 5nm~100nm calculated from the specific surface area value measured by the nitrogen adsorption method. The cross-linking agent is a compound composed of only hydrogen atoms, carbon atoms, nitrogen atoms and oxygen atoms and has 2 or more groups selected from the group consisting of hydroxyl groups, epoxy groups and alkoxy groups with 1 to 5 carbon atoms, And it is made of a compound with a cyclic structure, and the mass ratio of the polyimide to the silica particles is 7:3~3:7,

[In the formula, B ¹ represents a tetravalent group selected from the group formed by the formula (X-1)~(X-12),

(in the formula, a plurality of Rs independently represent a hydrogen atom or a methyl group, and * represents a bond)] H ₂ NB ² -NH ₂ (A1) (in the formula, B ² represents the formulas (Y-1) to (Y -34) bivalent bases selected from the group formed),

(in the formula, * represents a bond bond)

The composition for forming a resin film according to claim 1, wherein the silica particles have an average particle diameter of 60 nm or less. A resin film comprising the resin of claim 1 or claim 2 The composition for forming a thin film is formed.