KR102345844B1 - Method for producing resin thin film, and composition for forming resin thin film - Google Patents

Abstract

[Problem] A resin thin film having excellent heat resistance and low retardation, in particular, a method for manufacturing a resin thin film suitable as a substrate for a flexible device, and a resin thin film forming composition for providing the resin thin film intended to provide
[Solutions] A polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic acid dianhydride with a diamine component containing a fluorinated aromatic diamine, measured by a nitrogen adsorption method A method for producing a resin thin film, comprising using a composition for forming a resin thin film comprising silicon dioxide particles having an average particle diameter of 100 nm or less and an organic solvent calculated from a specific surface area value.

Description

The manufacturing method of a resin thin film and the composition for resin thin film formation

The present invention relates to a method for manufacturing a resin thin film and a composition for forming a resin thin film, a resin thin film obtained therefrom, and a method for reducing retardation of the resin thin film, and more specifically, to a display such as a flexible display substrate It relates to a method for producing a thin resin film suitable for use in a substrate, and a composition for forming a resin thin film.

In recent years, with the rapid progress of electronics, such as a liquid crystal display and an organic electroluminescent display, thickness reduction and weight reduction of a device have come to be calculated|required further and made flexible.

In these devices, various electronic elements, for example, thin film transistors and transparent electrodes, are formed on a glass substrate. By changing this glass material to a flexible and lightweight resin material, the device itself becomes thinner, lighter, and more flexible. is planned And as a candidate for such a resin material, a polyimide attracts attention, and various reports regarding a polyimide film are made|formed conventionally (for example, refer patent document 1, 2).

Japanese Patent Laid-Open No. S60-188427 Japanese Patent Laid-Open No. S58-208322 International Publication No. 2011/149018 pamphlet

By the way, when a polyimide resin material is used as a substrate of a display, it is preferable and required that the resin material be a material not only excellent in transparency but also having low retardation as one of the required performance. Also in the flexible display substrate, it is necessary to satisfy these requirements in addition to high flexibility (flexibility). Here, the retardation (phase difference) refers to the product of the birefringence (difference of two orthogonal refractive indices) and the film thickness. It is known that a large retardation value may cause the fall of the display quality of a display (for example, refer patent document 3).

The present invention has been made in view of these circumstances, and a resin thin film having excellent heat resistance and flexibility as well as low retardation, in particular a method for manufacturing a resin thin film suitable as a substrate for a flexible device, and the resin thin film; An object of the present invention is to provide a composition for forming a resin thin film that provides such a thin resin film.

In particular, the present invention is not only excellent in heat resistance and flexibility, but also has the characteristics of low retardation, and further excellent in transparency, suitable as a base film for a display substrate, especially a resin having excellent performance as a base film for a flexible display substrate It is also an object to provide a method for manufacturing a thin film, a resin thin film, and a composition for forming a resin thin film providing such a resin thin film.

Another object of the present invention is to provide a method for reducing the retardation of a thin resin film that can be used as a substrate for a flexible device or the like.

As a result of repeated intensive studies to achieve the above object, the present inventors have found that a resin thin film in which silicon dioxide is blended with a polyimide having a monomer unit of a specific structure has excellent heat resistance, low retardation, and furthermore excellent flexibility. It has been found that a resin thin film having the characteristics that completed the invention.

That is, the present invention is, as a first aspect, a method for producing a resin thin film,

A polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic acid dianhydride with a diamine component containing a fluorinated aromatic diamine;

Silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method, and

organic solvent

It relates to a method characterized by using a composition for forming a resin thin film comprising a.

As a second aspect, it relates to the method according to the first aspect, wherein the alicyclic tetracarboxylic dianhydride includes the tetracarboxylic dianhydride represented by formula (C1).

[Formula 1]

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

[Formula 2]

(In the formula, a plurality of R's each independently represent a hydrogen atom or a methyl group, and * represents the number of bonds.)]

As a 3rd viewpoint, it relates to the method as described in the 1st viewpoint or 2nd viewpoint, in which the said fluorine-containing aromatic diamine contains the diamine represented by Formula (A1).

[Formula 3]

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

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

(In the formula, * represents the number of bonds.)

As a 4th viewpoint, it is related with the method as described in the 1st viewpoint in which the said polyimide contains the monomer unit represented by Formula (2).

[Formula 9]

As a 5th viewpoint, the mass ratio of the said polyimide and the said silicon dioxide particle is 7:3-3:7, It relates to the method in any one of 1st viewpoint thru|or 4th viewpoint.

As a 6th viewpoint, the said average particle diameter is 60 nm or less It relates to the method in any one of 1st viewpoint - 5th viewpoint.

As a seventh aspect, it relates to a resin thin film produced by the method according to any one of the first to sixth aspects.

As an eighth aspect, a polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic acid dianhydride with a diamine component containing a fluorinated aromatic diamine;

Silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method, and

organic solvent

It relates to a composition for forming a resin thin film comprising a.

As a ninth viewpoint, it relates to the composition for resin thin film formation as described in the 8th viewpoint in which the said alicyclic tetracarboxylic dianhydride contains the tetracarboxylic dianhydride represented by Formula (C1).

[Formula 10]

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

[Formula 11]

(In the formula, a plurality of R's each independently represent a hydrogen atom or a methyl group, and * represents the number of bonds.)]

As a (10th) viewpoint, it relates to the composition for resin thin film formation as described in an 8th viewpoint or a 9th viewpoint, in which the said fluorine-containing aromatic diamine contains the diamine represented by Formula (A1).

[Formula 12]

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

[Formula 13]

[Formula 14]

[Formula 15]

[Formula 16]

[Formula 17]

(In the formula, * represents the number of bonds.)

As an 11th viewpoint, the said polyimide contains the monomer unit represented by Formula (2), The composition for resin thin film formation of an 8th viewpoint.

[Formula 18]

As a twelfth viewpoint, the mass ratio of the said polyimide and the said silicon dioxide particle is 7:3 - 3:7, It relates to the composition for resin thin film formation in any one of an 8th viewpoint - an eleventh viewpoint.

As a 13th viewpoint, the said average particle diameter is 60 nm or less It relates to the composition for resin thin film formation in any one of an 8th viewpoint - a 12th viewpoint.

As a fourteenth aspect, as a method for reducing the retardation of the resin thin film,

A polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic acid dianhydride with a diamine component containing a fluorinated aromatic diamine;

Silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method, and

organic solvent

It relates to a method characterized in that the resin thin film is formed using a composition for forming a resin thin film comprising a.

According to the method for manufacturing a resin thin film according to an aspect of the present invention using the composition for forming a resin thin film according to an aspect of the present invention, it has a low coefficient of linear expansion, excellent heat resistance, low retardation, and further excellent flexibility. A resin thin film can be formed with good reproducibility.

In particular, according to the method for producing a resin thin film according to another aspect of the present invention using the composition for forming a resin thin film according to another aspect of the present invention, it has a low coefficient of linear expansion, excellent heat resistance, high transparency and low retardation. Furthermore, it is possible to form a resin thin film excellent in flexibility with good reproducibility.

In addition, the resin thin film according to the present invention exhibits a low coefficient of linear expansion, high transparency (high light transmittance, low yellowness), low retardation, and is further excellent in flexibility, making it suitable as a substrate for a flexible device, particularly a flexible display. can be used readily.

Furthermore, according to the method for reducing the retardation of the resin thin film according to the present invention, it is possible to effectively reduce the retardation of the resin thin film.

The manufacturing method, composition, resin thin film and retardation reduction method according to the present invention is a flexible device requiring characteristics such as high flexibility, low coefficient of linear expansion, high transparency (high light transmittance, low yellowness), and low retardation. It can fully respond to the progress in the field|area of a board|substrate for use in a flexible display, especially a board|substrate for flexible displays.

Hereinafter, the present invention will be described in detail.

The composition for forming a resin thin film used in the method for manufacturing a resin thin film of the present invention contains the following specific polyimide, silicon dioxide particles and an organic solvent, and the composition for forming a resin thin film is also a subject of the present invention.

[Polyimide]

The polyimide used in the present invention is a polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic acid dianhydride with a diamine component containing a fluorinated aromatic diamine.

Among these, the alicyclic tetracarboxylic dianhydride includes tetracarboxylic dianhydride represented by the following formula (C1), and the fluorinated aromatic diamine includes a diamine represented by the following formula (A1) desirable.

[Formula 19]

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

[Formula 20]

(In the formula, a plurality of R's each independently represent a hydrogen atom or a methyl group, and * represents the number of bonds.)]

[Formula 21]

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

[Formula 22]

[Formula 23]

[Formula 24]

[Formula 25]

[Formula 26]

(In the formula, * represents the number of bonds.)

Among the tetracarboxylic dianhydrides represented by the formula (C1), B ¹ in the formula is a compound represented by the formulas (X-1), (X-4), (X-6), and (X-7). desirable.

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

As a suitable example, the polyimide obtained by imidating the polyamic acid obtained by making tetracarboxylic dianhydride represented by the said Formula (C1) react with the diamine represented by the said Formula (A1) is Formula (2) mentioned later The indicated monomer unit is included.

In order to obtain a resin thin film having characteristics of low linear expansion coefficient, low retardation and high transparency, and excellent in flexibility, which is the object of the present invention, alicyclic tetracarboxylic dianhydride, for example, with respect to the total number of moles of tetracarboxylic dianhydride component For example, the amount of tetracarboxylic dianhydride represented by the formula (C1) is preferably 90 mol% or more, more preferably 95 mol% or more, and particularly, the total (100 mol%) of the tetracarboxylic acid dianhydride represented by the formula (C1) is It is optimal that the main acid is an anhydride.

Similarly, in order to obtain a resin thin film having the characteristics of low linear expansion coefficient, low retardation and high transparency, and excellent in flexibility, a fluorinated aromatic diamine, for example, represented by formula (A1) with respect to the total number of moles of the diamine component It is preferable that the diamine used is 90 mol% or more, and it is more preferable that it is 95 mol% or more. In addition, the whole diamine component (100 mol%) may be a diamine represented by the above formula (A1).

As an example of a suitable aspect, the polyimide used by this invention contains the monomer unit represented by following formula (1).

[Formula 27]

As the monomer unit represented by the formula (1), it is preferably represented by formula (1-1) or (1-2), and more preferably represented by formula (1-1).

[Formula 28]

According to a preferred aspect of the present invention, the polyimide used in the present invention further contains a monomer unit represented by the formula (2) in addition to the monomer unit represented by the formula (1).

[Formula 29]

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

[Formula 30]

When the polyimide used in the present invention contains the monomer unit represented by the formula (1) and the monomer unit represented by the formula (2), the molar ratio in the polyimide chain is the monomer unit represented by the formula (1). : Monomer unit represented by formula (2) = preferably included in a ratio of 10:1 to 1:10, more preferably in a ratio of 10:1 to 3:1.

The polyimide of the present invention is derived from an alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic acid dianhydride represented by the formula (C1) described above and a diamine component containing the diamine represented by the formula (A1). In addition to the monomer units to be used, for example, the monomer units represented by the formulas (1) and (2), other monomer units may be included. The content ratio of this other monomer unit is arbitrarily determined as long as the properties of the resin thin film formed from the composition for forming a resin thin film of the present invention are not impaired. The ratio is a monomer unit derived from the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic acid dianhydride represented by the formula (C1) and the diamine component containing the diamine represented by the formula (A1). , for example, with respect to the number of moles of the monomer unit represented by the formula (1), or when the monomer unit represented by the formula (2) is included, the monomer unit represented by the formula (1) and the formula (2) With respect to the total number of moles of the monomer units used, less than 20 mol% is preferable, less than 10 mol% is more preferable, and it is still more preferable that it is less than 5 mol%.

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

[Formula 31]

In formula (3), A represents a tetravalent organic group, and preferably represents a tetravalent group represented by any one of the following formulas (A-1) to (A-4). In the formula (3), B represents 2 represents a valent organic group, preferably a divalent group represented by any one of formulas (B-1) to (B-11). In each formula, * represents the number of bonds. On the other hand, in formula (3), A is When a tetravalent group represented by any one of the following formulas (A-1) to (A-4) is represented, B may be a divalent group represented by any one of the aforementioned formulas (Y-1) to (Y-34). Or in formula (3), when B represents a divalent group represented by any one of the following formulas (B-1) to (B-11), A is any of the above-mentioned formulas (X-1) to (X-12) It may be a tetravalent group represented by one.

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

[Formula 32]

[Formula 33]

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

As a preferable example, the polyimide having a monomer unit represented by the formula (1) is bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic acid as a tetracarboxylic dianhydride component. It is obtained by polymerizing a dianhydride and the diamine represented by following formula (4) as a diamine component in an organic solvent, and imidating the polyamic acid obtained.

In addition, when the polyimide used in the present invention has a monomer unit represented by the formula (2) in addition to the monomer unit represented by the formula (1), each represented by the formulas (1) and (2) A polyimide containing a monomer unit is prepared by the following formula (4) as a tetracarboxylic dianhydride component and 1,2,3,4-cyclobutanetetracarboxylic dianhydride as a diamine component in addition to the tetracarboxylic dianhydride. It is obtained by polymerizing the displayed diamine in an organic solvent, and imidating the polyamic acid obtained.

[Formula 34]

Examples of the diamine represented by the formula (4) include 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, and 2,3'-bis(trifluoromethyl)benzidine. methyl)benzidine.

Among these, as a diamine component, the 2,2'-bis represented by the following formula (4-1) from a viewpoint of making the linear expansion coefficient which the resin thin film of this invention has lower and making the transparency of a resin thin film higher. It is preferable to use (trifluoromethyl)benzidine or 3,3'-bis(trifluoromethyl)benzidine represented by the following formula (4-2), especially 2,2'-bis(trifluoromethyl) It is preferable to use benzidine.

[Formula 35]

Moreover, the polyimide used by this invention contains the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by Formula (C1) mentioned above, and the diamine containing the diamine represented by Formula (A1). In the case of having another monomer unit represented by the formula (3) in addition to the monomer unit derived from the component, for example, the monomer unit represented by the formula (1) and the monomer unit represented by the formula (2), the formula ( 1), the polyimide containing each monomer unit represented by the formulas (2) and (3), as a tetracarboxylic dianhydride component, in addition to the above two types of tetracarboxylic dianhydride, the following formula (5) It is obtained by polymerizing the diamine represented by the following formula (6) in an organic solvent in addition to the tetracarboxylic dianhydride represented by and the diamine represented by the formula (4) as a diamine component, and imidizing the resulting polyamic acid.

[Formula 36]

A in Formula (5) and B in Formula (6) show the same meaning as A and B in Formula (3) mentioned above, respectively.

Specifically, examples of the tetracarboxylic dianhydride represented by the formula (5) include 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'-diphenylsulfonetetracarboxylic dianhydride, 4 ,4'-(hexafluoroisopropylidene)diphthalic dianhydride, 11,11-bis(trifluoromethyl)-1H-difluoro[3,4-b:3',4'-i] Santhene-1,3,7,9-(11H-tetraone), 6,6'-bis(trifluoromethyl)-[5,5'-biisobenzofuran]-1,1',3,3 '-Tetraone, 4,6,10,12-tetrafluorodifuro[3,4-b:3',4'-i]dibenzo[b,e][1,4]dioxine-1,3 ,7,9-tetraone, 4,8-bis(trifluoromethoxy)benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetraone, N, N'-[2,2'-bis(trifluoromethyl)biphenyl-4,4'-diyl]bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxamide ), such as aromatic tetracarboxylic acids; 1,2-Dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1 ,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1 -alicyclic tetracarboxylic dianhydride, such as naphthalene succinic dianhydride; Although aliphatic tetracarboxylic dianhydride, such as 1,2,3,4- butanetetracarboxylic dianhydride, is mentioned, It is not limited to these.

Among these, tetracarboxylic dianhydride is preferable, in which A in formula (5) is a tetravalent group represented by any one of formulas (A-1) to (A-4), that is, 11,11-bis(trifluoro methyl)-1H-difluoro[3,4-b:3′,4′-i]xanthene-1,3,7,9-(11H-tetraone), 6,6′-bis(trifluoro Rhomethyl)-[5,5'-biisobenzofuran]-1,1',3,3'-tetraone, 4,6,10,12-tetrafluorodifuro[3,4-b:3',4'-i]dibenzo[b,e][1,4]dioxine-1,3,7,9-tetraone, 4,8-bis(trifluoromethoxy)benzo[1,2-c :4,5-c']difuran-1,3,5,7-tetraone is mentioned as a preferable compound.

Further, examples of the diamine represented by the formula (6) include 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, tetrakis(trifluoromethyl) )-1,4-phenylenediamine, 2-(trifluoromethyl)-1,3-phenylenediamine, 4-(trifluoromethyl)-1,3-phenylenediamine, 2-methoxy-1 ,4-phenylenediamine, 2,5-dimethoxy-1,4-phenylenediamine, 2-hydroxy-1,4-phenylenediamine, 2,5-dihydroxy-1,4-phenylenediamine , 2-fluorobenzene-1,4-diamine, 2,5-difluorobenzene-1,4-diamine, 2-chlorobenzene-1,4-diamine, 2,5-dichlorobenzene-1,4- Diamine, 2,3,5,6-tetrafluorobenzene-1,4-diamine, 4,4'-(perfluoropropane-2,2-diyl)dianiline, 4,4'-oxybis[3 -(trifluoromethyl)aniline], 1,4-bis(4-aminophenoxy)benzene, 1,3'-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy) ) Benzene, benzidine, 2-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'-dihydroxybenzidine, 3,3'-dihydroxybenzidine, 2,3'-dihydroxybenzidine, 2,2'-difluorobenzidine, 3,3'-difluorobenzidine, 2, 3'-difluorobenzidine, 2,2'-dichlorobenzidine, 3,3'-dichlorobenzidine, 2,3'-dichlorobenzidine, 4,4'-diaminobenzanilide, 4-aminophenyl-4'- Aminobenzoate, octafluorobenzidine, 2,2',5,5'-tetramethylbenzidine, 3,3',5,5'-tetramethylbenzidine, 2,2',5,5'-tetrakis ( trifluoromethyl)benzyl Dean, 3,3',5,5'-tetrakis(trifluoromethyl)benzidine, 2,2',5,5'-tetrachlorobenzidine, 4,4'-bis(4-aminophenoxy) ratio Phenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-{[3,3"-bis(trifluoromethyl)-(1,1':3',1"- terphenyl)-4,4"-diyl]-bis(oxy)}dianiline, 4,4'-{[(perfluoropropane-2,2-diyl)bis(4,1-phenylene)]bis aromatic diamines such as (oxy)}dianiline and 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5(or 6)amine; 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(3-methylcyclohexylamine), isophoronediamine, trans-1,4-cyclohexanediamine, cis-1,4-cyclo Hexanediamine, 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-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1, Although aliphatic diamines, such as 8-octamethylenediamine and 1,9- nonamethylenediamine, are mentioned, It is not limited to these.

Among these, aromatic diamines in which B in formula (6) is a divalent group represented by any one of formulas (B-1) to (B-11) are preferable, that is, 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, 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(trifluoro Romethyl)-(1,1':3',1"-terphenyl)-4,4"-diyl]-bis(oxy)}dianiline, 4,4'-{[(perfluoropropane-2 ,2-diyl)bis(4,1-phenylene)]bis(oxy)}dianiline, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene A -5 (or 6) amine is mentioned as a preferable diamine.

<Synthesis of polyamic acid>

As described above, the polyimide used in the present invention includes a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride represented by the formula (C1), and a compound represented by the formula (A1). It is obtained by imidating the polyamic acid obtained by making the diamine component containing a fluorine aromatic diamine react.

Specifically, for example, as a preferred example, bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic dianhydride, and optionally 1,2,3,4-cyclo A tetracarboxylic dianhydride component consisting of butanetetracarboxylic dianhydride and, if necessary, tetracarboxylic dianhydride represented by the formula (5), the diamine represented by the formula (4), and optionally the formula ( It is obtained by polymerizing the diamine component which consists of the diamine component represented by 6) in an organic solvent, and imidating the polyamic acid obtained.

The reaction from the two components to the polyamic acid is advantageous in that it can proceed relatively easily in an organic solvent and no by-products are generated.

The input ratio (molar ratio) of the diamine component in the reaction of these tetracarboxylic dianhydride components and the diamine component is appropriately set in consideration of the molecular weight of the polyamic acid and the polyimide obtained by imidation thereafter, but the diamine component With respect to 1, the tetracarboxylic dianhydride component can be usually set to about 0.8 to 1.2, for example, about 0.9 to 1.1, preferably about 0.95 to 1.02. As in a normal polycondensation reaction, the closer this molar ratio to 1.0, the greater the molecular weight of the polyamic acid produced.

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 polyamic acid. The specific example is given below.

For example, m-cresol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N,N-dimethylform Amide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropylamide, 3-ethoxy-N,N-dimethylpropylamide, 3-propoxy-N,N-dimethylpropylamide, 3 -isopropoxy -N,N-dimethylpropylamide, 3-butoxy-N,N-dimethylpropylamide, 3-sec-butoxy-N,N-dimethylpropylamide, 3-tert-butoxy-N, N-dimethylpropylamide, γ-butyrolactone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl Amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellusolve, ethyl cellusolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, Ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether, dipropylene glycol monomethyl ether, Diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene Glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether , diisobutylene, amyl acetate, butyl butyrate, butyl ether, 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 ether, pyruvate Tyl, ethyl pyruvate, 3-methyl propionate, 3-methyl ethyl propionate, 3-ethoxy ethyl propionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, 3-methoxy Butyl propionate, diglyme, 4-hydroxy-4-methyl-2-pentanone, etc. are mentioned, but are not limited to these. These may be used individually or in combination of 2 or more types.

Furthermore, even if it is a solvent in which a polyamic acid is not dissolved, you can also use it in the range in which the produced|generated polyamic acid does not precipitate, mixing with the said solvent. In addition, moisture in the organic solvent not only inhibits the polymerization reaction, but also causes hydrolysis of the produced polyamic acid, so it is preferable to use a dehydrated and dried organic solvent as much as possible.

As a method of reacting the tetracarboxylic dianhydride component and the diamine component in an organic solvent, a dispersion or solution in which the diamine component is dispersed or dissolved in an organic solvent is stirred, and the tetracarboxylic acid dianhydride component is added thereto as it is, Or a method of adding a dispersion or dissolution of the component in an organic solvent, a method of adding a diamine component to a dispersion or solution in which a tetracarboxylic dianhydride component is dispersed or dissolved in an organic solvent, and a method of adding a tetracarboxylic acid dianhydride component and The method of adding diamine compound components alternately, etc. are mentioned, Any of these methods may be sufficient.

In addition, when the tetracarboxylic dianhydride component and/or the diamine component consists of a plurality of types of compounds, the reaction may be carried out in a pre-mixed state, the reaction may be carried out individually, and the low molecular weight substance reacted separately may be mixed. It can also be made into a high molecular weight body by making it react.

The temperature at the time of synthesizing the polyamic acid may be appropriately set within the range from the melting point to the boiling point of the solvent to be used, for example, an arbitrary temperature of -20°C to 150°C can be selected, but -5°C to It is good that it is 100 degreeC, normally about 0-100 degreeC, Preferably it is about 0-70 degreeC.

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

In addition, although the reaction can be carried out at any concentration, if the concentration is too low, it becomes difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring becomes difficult, so tetracarboxylic dianhydride The total concentration in the reaction solution of the component and the diamine component is preferably 1 to 50 mass%, more preferably 5 to 40 mass%. In the initial stage of the reaction, it may be carried out at a high concentration, and thereafter, an organic solvent may be added.

<Imidation of polyamic acid>

As a method of imidating a polyamic acid, thermal imidation which heats the solution of a polyamic acid as it is, and catalyst imidation which adds a catalyst to the solution of a polyamic acid is mentioned.

The temperature in the case of thermal imidization of polyamic acid in solution is 100 degreeC - 400 degreeC, Preferably it is 120 degreeC - 250 degreeC, It is preferable to carry out while removing the water produced|generated by the imidation reaction outside the system.

Chemical (catalytic) imidization of polyamic acid is performed by adding a basic catalyst and acid anhydride to a solution of polyamic acid, and stirring the inside of the system at a temperature condition of -20 to 250 ° C, preferably 0 to 180 ° C. can

The amount of the basic catalyst is 0.5 to 30 mole times, preferably 1.5 to 20 mole times, of the amic acid group of the polyamic acid, and the amount of the acid anhydride is 1 to 50 mole times, preferably 2 to 30 mole times of the amic acid group of the polyamic acid.

Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and 1-ethylpiperidine. Among them, pyridine is preferable because it has suitable basicity for the reaction to proceed.

Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride. Among them, acetic anhydride is preferably used because purification after completion of the reaction is facilitated.

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

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

In the present invention, after filtering the reaction solution, the filtrate may be used as it is, or diluted or concentrated, and silicon dioxide or the like described later may be blended thereto to obtain a composition for forming a resin thin film. In the case of filtration in this way, it is possible to not only reduce the mixing of impurities that may cause deterioration of the heat resistance, flexibility, or coefficient of linear expansion characteristics of the resulting resin thin film, but also efficiently obtain a composition for forming a resin thin film.

In addition, the polyimide used in the present invention has a weight average molecular weight ( Mw) is preferably 5,000 to 200,000.

<Polymer recovery>

What is necessary is just to inject|throw-in the reaction solution to a poor solvent and just to precipitate, when collect|recovering and using a polymer component from the reaction solution of a polyamic acid and a polyimide. Examples of the poor solvent used for precipitation include methanol, acetone, hexane, butyl cellusolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and water. The polymer precipitated by putting it in the poor solvent can be collected by filtration, and then dried under normal pressure or reduced pressure at room temperature or by heating.

In addition, if the precipitation-recovered polymer is redissolved in an organic solvent and the operation of re-precipitating and recovering is repeated 2 to 10 times, impurities in the polymer can be reduced. At this time, when three or more types of poor solvents, such as alcohol, ketones, hydrocarbons, are used as a poor solvent, since the efficiency of refinement|purification further increases, it is preferable.

The organic solvent that dissolves the resin component in the reprecipitation recovery step is not particularly limited. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, dipentene, ethylamylketone, methyl Nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, etc. are mentioned. These solvents can also be used in mixture of 2 or more types.

[silicon dioxide]

Silicon dioxide (silica) used in the present invention is not particularly limited, but silicon dioxide in particle form, for example, has an average particle diameter of 100 nm or less, for example, 5 nm to 100 nm, preferably 5 nm to 55 nm, and a more transparent thin film From the viewpoint of obtaining good reproducibility, preferably 5 nm to 50 nm, more preferably 5 nm to 45 nm, still more preferably 5 nm to 35 nm, still more preferably 5 nm to 30 nm.

In the present invention, the average particle diameter of the silicon dioxide particles is an average particle diameter value calculated from the specific surface area value measured by the nitrogen adsorption method using the silicon dioxide particles.

In particular, in the present invention, colloidal silica having the above average particle diameter can be suitably used, and silica sol can be used as the colloidal silica. As the silica sol, an aqueous silica sol prepared by a known method using an aqueous sodium silicate solution as a raw material and an organosilica sol obtained by substituting an organic solvent for water as a dispersion medium of the aqueous silica sol can be used.

In addition, silica sol obtained by hydrolyzing an alkoxysilane such as methyl silicate or ethyl silicate in an organic solvent such as alcohol in the presence of a catalyst (eg, ammonia, an organic amine compound, an alkali catalyst such as sodium hydroxide) and condensing , or organosilica sol obtained by solvent replacement of the silica sol with another organic solvent can also be used.

Among these, in the present invention, it is preferable to use organosilicasol as the dispersion medium as an organic solvent.

Examples of the organic solvent in the above-mentioned organosilicasol include lower alcohols such as methyl alcohol, ethyl alcohol and isopropanol; straight-chain amides such as N,N-dimethylformamide and N,N-dimethylacetamide; cyclic amides such as N-methyl-2-pyrrolidone; ethers such as γ-butyrolactone; Glycols, such as ethyl cellosolve and ethylene glycol, acetonitrile, etc. are mentioned. This substitution can be performed by a conventional method such as a distillation method, an ultrafiltration method, or the like.

The viscosity of the said organosilicasol is about 0.6 mPa*s - 100 mPa*s at 20 degreeC.

Examples of the commercially available organosilica sol include, for example, trade name MA-ST-S (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MT-ST (methanol-dispersed silica sol, Nissan Chemical Industries, Ltd.) .), trade name MA-ST-UP (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MA-ST-M (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MA-ST -L (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST-S (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST (isopropanol-dispersed silica sol, Nissan Chemical) Industries, Ltd.), trade name IPA-ST-UP (isopropanol dispersed silica sol, Nissan Chemical Industries, Ltd.), trade name IPA-ST-L (isopropanol dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST-ZL (isopropanol dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name NPC-ST-30 (n-propylcellosolve dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name PGM-ST (1-methoxy-2-propanol dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name DMAC-ST (dimethylacetamide dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name XBA-ST (xylene) ·N-butanol mixed solvent dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name EAC-ST (ethyl acetate 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, manufactured by Nissan Chemical Industries, Ltd.), and trade name MIBK-ST (methyl isobutyl ketone dispersed) silica sol (manufactured by Nissan Chemical Industries, Ltd.) and the like, but is not limited thereto.

In the present invention, silicon dioxide, for example, silicon dioxide as cited as the above product used as organosilicasol may be used in a mixture of two or more.

[Organic solvent]

The composition for forming a resin thin film of the present invention contains an organic solvent in addition to the polyimide and silicon dioxide. This organic solvent is not specifically limited, For example, the thing similar to the specific example of the reaction solvent used at the time of preparation of the said polyamic acid and a polyimide is mentioned. More specifically, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2- pyrrolidone, γ-butyrolactone, and the like. In addition, an organic solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

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

[Composition for resin thin film formation]

This invention is the composition for resin thin film formation containing the said polyimide, silicon dioxide, and an organic solvent. Here, the composition for forming a resin thin film of the present invention is uniform, and phase separation is not recognized.

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

Moreover, the compounding quantity of the solid content in the composition for resin thin film formation of this invention is about 0.5-30 mass % normally, Preferably it is about 5-25 mass %. When the solid content concentration is less than 0.5% by mass, the film forming efficiency in producing the resin thin film is lowered and the viscosity of the composition for forming the resin thin film is lowered, so that it is difficult to obtain a coating film having a uniform surface. Moreover, when solid content concentration exceeds 30 mass %, the viscosity of the composition for resin thin film formation becomes high too much, and there exists a possibility that the film-forming efficiency also deteriorates and the surface uniformity of a coating film lacks. In addition, the solid content here means the total mass of components other than an organic solvent, and even if it is a liquid monomer, etc., it is included in weight as solid content.

On the other hand, the viscosity of the composition for forming a resin thin film is appropriately set in consideration of the thickness of the resin thin film to be produced. It is about 50,000 mPa·s, preferably about 1,000 to 20,000 mPa·s.

In order to impart processing characteristics and various functionalities to the composition for forming a resin thin film of the present invention, various other organic or inorganic low-molecular or high-molecular compounds may be blended. For example, a catalyst, an antifoaming agent, a leveling agent, surfactant, dye, a plasticizer, microparticles|fine-particles, a coupling agent, a sensitizer, etc. can be used. For example, the catalyst may be added for the purpose of reducing the retardation or the coefficient of linear expansion of the resin thin film. On the other hand, in addition to the polyimide, silicon dioxide and the organic solvent, a composition for forming a resin thin film further comprising a catalyst can be made the object of the present invention.

The composition for forming a resin thin film of the present invention can be obtained by dissolving the polyimide and silicon dioxide obtained by the above-described method in the above-mentioned organic solvent, and adding silicon dioxide to the reaction solution after preparation of the polyimide, if necessary The organic solvent may be further added.

[Resin Thin Film]

The composition for forming a resin thin film of the present invention described above is applied to a base material, dried and heated to remove the organic solvent, and a resin thin film having high heat resistance, high transparency, moderate flexibility, and a suitable coefficient of linear expansion, and further with low retardation, is produced. can be obtained

And the said resin thin film, ie, the said polyimide, and the said resin thin film containing the said inorganic silica compound is also an object of this invention. Furthermore, in addition to the polyimide and silicon dioxide, a resin thin film further containing a catalyst is also a subject of the present invention.

As a base material used for manufacture of a resin thin film, For example, plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetyl cellulose, ABS, AS, norbornene-type resin, etc.), metal , stainless steel (SUS), wood, paper, glass, silicon wafer, slate, and the like.

In particular, in the case of application as a substrate material for an electronic device, from the viewpoint that existing equipment can be used, it is preferable that the substrate to be applied is glass or a silicon wafer, and it is advantageous in that the obtained resin thin film exhibits good peelability. It is more preferable that On the other hand, the coefficient of linear expansion of the substrate to be applied is 30 ppm/°C or less, more preferably 20 ppm/°C or less, from the viewpoint of warpage of the substrate after coating.

The coating method of the composition for forming a resin thin film on the substrate is not particularly limited, but for example, a cast coating method, a spin coating method, a blade coating method, a dip coating method, a roll coating method, a bar coating method, a die coating method, The inkjet method and the printing method (iron plate, intaglio, flat plate, screen printing, etc.) etc. are mentioned, According to the objective, these can be used suitably.

As for heating temperature, 300 degrees C or less is preferable. When it exceeds 300 degreeC, the resin thin film obtained becomes brittle, and the resin thin film suitable especially for a display substrate use may not be obtained.

In addition, in consideration of the heat resistance and linear expansion coefficient characteristics of the obtained resin thin film, the applied composition for forming a resin thin film is heated at 40° C. to 100° C. for 5 minutes to 2 hours, and then the heating temperature is raised stepwise as it is, and finally 175° C. It is preferable to heat at excess -280 degreeC for 30 minutes - 2 hours. In this way, by heating at a temperature of two or more steps of drying the solvent and promoting molecular orientation, low thermal expansion characteristics can be expressed.

In particular, the applied composition for forming a thin resin film is heated at 40° C. to 100° C. for 5 minutes to 2 hours, and then at over 100° C. to 175° C. for 5 minutes to 2 hours, and then at more than 175° C. to 280° C. for 5 minutes. It is preferable to heat for ~2 hours.

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

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

On the other hand, the method for peeling the resin thin film formed in this way from the substrate is not particularly limited, and the method for peeling the resin thin film by cooling the entire resin thin film and putting a cut in the thin film, or a method for peeling by applying tension through a roll and the like.

The resin thin film according to a preferred aspect of the present invention obtained in this way can realize high transparency such that the light transmittance at a wavelength of 400 nm is 75% or more.

Furthermore, this resin thin film may have a low value such as, for example, a coefficient of linear expansion at 50° C. to 200° C. of 60 ppm/° C. or less, particularly 10 ppm/° C. to 35 ppm/° C., and, for example, 200° C. to The coefficient of linear expansion at 250° C. is 80 ppm/° C. or less, and in particular, it can have a low value such as 15 ppm/° C. to 55 ppm/° C., and is excellent in dimensional stability during heating.

_{In particular, this resin thin film has an in-plane retardation R 0} expressed by the product of the birefringence (difference of two orthogonal refractive indices in the plane) and the film thickness when the wavelength of incident light is 590 nm, and in the cross section in the thickness direction _{The thickness direction retardation R th} expressed by the average value of the two phase differences obtained by multiplying the film thickness by each of the two birefringence (the difference between the two in-plane refractive indices and the refractive index in the thickness direction) when viewed is very small. make it special When the average film thickness of the resin thin film of the present invention is 15 µm to 40 µm, the retardation R _th in the thickness direction is less than 700 nm, for example, 660 nm or less, for example, 10 nm to 660 nm, and the in-plane retardation R ₀ is 4 It is less than, for example, 0.3 to 3.9, and the birefringence Δn has a very low value of less than 0.02, for example, 0.0003 to 0.019.

Thus, by forming a resin thin film using the composition for resin thin film formation of this invention, the retardation of this resin thin film can be reduced, and the method of reducing such retardation of a resin thin film is also an object of this invention.

Since the resin thin film of the present invention described above has the above characteristics, it satisfies each condition required as a base film for a flexible display substrate, and can be particularly suitably used as a base film for 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 the following examples.

The meanings of the weak symbols used in the following examples are as follows.

<Acid dianhydride>

BODA: bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic dianhydride

CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

TCA: 2,3,5-tricarboxycyclopentylacetic acid-1,4:2,3-dianhydride

BODAxx: Bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic dianhydride

<Diamine>

TFMB: 2,2'-bis(trifluoromethyl)benzidine

TMDA: 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5(or 6)amine

<Organic solvent>

DMAc: N,N-dimethylacetamide

NMP: N-methyl-2-pyrrolidone

DMF: N,N-dimethylformamide

IPA: isopropanol

GBL: γ-butyrolactone

<Silicasol>

IPA-ST: isopropanol dispersed silica sol (silica average particle diameter: 10 to 15 nm, silica solid content concentration: 30 mass %), manufactured by Nissan Chemical Industries, Ltd.

DMAC-ST: N,N-dimethylacetamide dispersed silica sol (silica average particle diameter: 10 to 15 nm, silica solid content concentration: 20 mass%), manufactured by Nissan Chemical Industries, Ltd.

GBL-ZL: γ-butyrolactone dispersed silica sol (silica solid content concentration: 25% by mass)

GBL-L: γ-butyrolactone dispersed silica sol (silica solid content concentration: 25% by mass)

GBL-M: γ-butyrolactone dispersed silica sol (silica solid content concentration: 30% by mass)

GBL-ST: γ-butyrolactone dispersed silica sol (silica solid content concentration: 30% by mass)

GBL-S: γ-butyrolactone dispersed silica sol (silica solid content concentration: 25% by mass)

GBL-UP: γ-butyrolactone dispersed silica sol (chain type, silica solid content concentration: 20% by mass)

On the other hand, the γ-butyrolactone dispersed silica sol (GBL-ZL, GBL-L, GBL-M, GBL-ST, GBL-S and GBL-UP) is prepared by Nissan Chemical Industries, Ltd. by the method described later. Isopropanol-dispersed silica sol (IPA-ST-ZL, IPA-ST-L, IPA-ST) and Nissan Chemical Industries, Ltd. methanol-dispersed silica sol (MA-ST-M, MA-ST-S, MA-ST) -UP) as a solvent, respectively, obtained by solvent replacement with γ-butyrolactone from isopropanol or methanol.

In addition, the silica average particle diameter in the said IPA-ST and DMAC-ST is a catalog value, In the silica sol used this time, the average particle diameter calculated from the specific surface area value measured by the nitrogen adsorption method is as follows. Specifically, the specific surface area of the dry powder of silica sol was measured using a specific surface area measuring device MONOSORB MS-16 manufactured by Yuasa Ionics Co., Ltd., and the measured specific surface area S (m ² /g) was used to measure the specific surface area. The average primary particle diameter was computed by the formula of D(nm)=2720/S.

IPA-ST average particle diameter: 12nm

DMAC-ST : 12nm

GBL-ZL:80nm

GBL-L :45nm

GBL-M :22nm

GBL-ST : 12nm

GBL-S: 9nm

GBL-UP : 12nm

In addition, in the Example, the apparatus and conditions used for preparation of a sample, and analysis and evaluation of a physical property are as follows.

1) Measurement of number average molecular weight and weight average molecular weight

The number average molecular weight (hereinafter referred to as Mn) and the weight average molecular weight (hereinafter referred to as Mw) of the polymer were measured by: Apparatus: Showa Denko KK, Showdex GPC-101, Column: KD803 and KD805, Column temperature: 50°C, elution Solvent: DMF, flow rate: 1.5 ml/min, calibration curve: measured under the conditions of standard polystyrene.

2) film thickness

The film thickness of the obtained resin thin film was measured with the Thickness Gauge manufactured by Teclock Corporation.

3) Coefficient of linear expansion (CTE)

Using TMA Q400 manufactured by TA Instruments, Inc., the thin resin film was cut into a size of 5 mm in width and 16 mm in length, first heated at 10° C./min and heated to 50 to 350° C. (first heating), then at 10° C./ The coefficient of linear expansion at 50°C to 200°C of the second heating (CTE [ ppm/°C]), and the values of the coefficient of linear expansion (CTE [ppm/°C]) at 200°C to 250°C were measured and obtained. On the other hand, a load of 0.05N was applied through the first heating, cooling, and second heating.

4) 5% weight loss temperature (Td _{5 %} )

The 5% weight loss temperature (Td _{5 %} [°C]) is measured by using TGA Q500 manufactured by TA Instruments, Inc., and heating about 5 to 10 mg of the resin thin film in nitrogen to 50 to 800°C at 10°C/min. was saved.

5) Light transmittance (transparency) (T _{400 nm} , T _{550 nm} ) and CIE b value (CIE b ^* )

_{Light transmittance (T 400 nm} , T _{550 nm} [%]) and CIE b value (CIE b ^* ) at wavelengths 400 nm and 550 nm were obtained from Nippon Denshoku Industries Co., Ltd. Using a SA4000 spectrometer manufactured by Ltd., the measurement was performed at room temperature with reference to air.

6) Retardation (R _th , R ₀ )

Thickness direction retardation (R _th ) and in-plane retardation (R ₀ ) were measured at room temperature using KOBURA 2100ADH manufactured by Oji Scientific Instruments Co., Ltd.

On the other hand, thickness direction retardation (R _th ) and in-plane retardation (R ₀ ) are computed by the following formula|equation.

R ₀ =(Nx-Ny)×d=ΔNxy×d

R _th =[(Nx+Ny)/2-Nz]×d=[(ΔNxz×d)+(ΔNyz×d)/2

Nx, Ny: two refractive indices orthogonal in-plane (Nx>Ny, Nx is also called slow axis, Ny is also called fast axis)

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

d: film thickness

ΔNxy: the difference between two in-plane refractive indices (Nx-Ny) (birefringence)

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

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

7) Birefringence (Δn)

It computed with the following formula using the value of _{thickness direction retardation (Rth} ) obtained by <6) retardation> mentioned above.

ΔN=[R _th /d (film thickness)]/1000

[1] Preparation example of silica sol

(Preparation Example 1: Preparation of GBL-M)

In a 1000 mL round-bottom flask, Nissan Chemical Industries, Ltd. methanol-dispersed silica sol: MA-ST-M 350 g (silica solid content concentration: 40.4 mass %) and γ-butyllactone 329.93 g were put. Then, the flask was connected to a vacuum evaporator to reduce the pressure in the flask, and immersed in a hot water bath at about 35° C. for 20 to 50 minutes. About 471 g of silica sol (GBL-M) in which the solvent was substituted with γ-butyllactone from methanol. was obtained (silica solid content concentration: 30 mass %).

(Preparation Example 2: Preparation of GBL-ZL)

Into a 1000 mL round-bottom flask, Nissan Chemical Industries, Ltd. isopropanol dispersion silica sol: IPA-ST-ZL 350 g (silica solid content concentration: 30 mass %) and 315 g of γ-butyllactone were put. Then, the flask is connected to a vacuum evaporator equipped with a chemical-resistant vacuum pump to reduce the pressure in the flask, and by immersing it in a hot water bath at about 35° C. for 30 to 60 minutes, silica sol substituted with γ-butyllactone from the solvent isopropanol ( GBL-ZL) about 420 g was obtained (silica solid content concentration: 25 mass %).

(Preparation Example 3: Preparation of GBL-L)

In a 1000 mL round-bottom flask, Nissan Chemical Industries, Ltd. isopropanol dispersion silica sol: IPA-ST-L 350 g (silica solid content concentration: 30 mass %) and 315 g of γ-butyllactone were put. Then, the flask is connected to a vacuum evaporator equipped with a chemical-resistant vacuum pump to reduce the pressure in the flask, and by immersing it in a hot water bath at about 35° C. for 30 to 60 minutes, silica sol substituted with γ-butyllactone from the solvent isopropanol ( GBL-L) about 420 g was obtained (silica solid content concentration: 25 mass %).

(Preparation Example 4: Preparation of GBL-ST)

In a 1000 mL round-bottom flask, Nissan Chemical Industries, Ltd. isopropanol-dispersed silica sol: 350 g of IPA-ST (silica solid content concentration: 30 mass%) and 245 g of γ-butyllactone were put. Then, the flask is connected to a vacuum evaporator equipped with a chemical-resistant vacuum pump to reduce the pressure in the flask, and by immersing it in a hot water bath at about 35° C. for 30 to 60 minutes, silica sol substituted with γ-butyllactone from the solvent isopropanol ( GBL-ST) about 350 g was obtained (silica solid content concentration: 30 mass %).

(Preparation Example 5: Preparation of GBL-S)

In a 1000 mL round-bottom flask, Nissan Chemical Industries, Ltd. methanol-dispersed silica sol: MA-ST-S 350 g (silica solid content concentration: 25 mass %) and γ-butyllactone 262.5 g were put. Then, the flask is connected to a vacuum evaporator equipped with a chemical-resistant vacuum pump to reduce the pressure in the flask, and immersed in a hot water bath at about 35° C. for 20 to 50 minutes. Silica sol in which the solvent is substituted with γ-butyllactone from methanol (GBL-S) about 350 g was obtained (silica solid content concentration: 25 mass %).

(Preparation Example 6: Preparation of GBL-UP)

In a 1000 mL round-bottom flask, Nissan Chemical Industries, Ltd. methanol dispersion silica sol: 350 g of MA-ST-UP (silica solid content concentration: 20 mass %) and 280 g of γ-butyllactone were put. Then, the flask is connected to a vacuum evaporator equipped with a chemical-resistant vacuum pump to reduce the pressure in the flask, and immersed in a hot water bath at about 35° C. for 20 to 50 minutes. Silica sol in which the solvent is substituted with γ-butyllactone from methanol (GBL-UP) about 350 g was obtained (silica solid content concentration: 20 mass %).

[2] Synthesis example

[Synthesis Example 1]

In a 2,000 mL flask equipped with a mechanical stirrer, 58 g (0.1811 mol) of TFMB and 188.23 g of DMAc were sequentially added and stirring was started. After nitrogen substitution by adding 36.25 g (0.1448 mol) of BODA to this, the mixture was stirred at 70° C. for 3 hours, and then the reaction mixture was cooled to 50° C., and 7.103 g (0.0362 mol) of CBDA was added thereto. , and stirred for 2 hours again. Then, the reaction mixture was cooled to room temperature and stirred again overnight. Then, DMAc was added to the reaction mixture, and the mixture was diluted so that the concentration of the solid content (concentration of components other than the organic solvent) was 5% by mass.

To the diluted reaction mixture, 73.96 g (0.7244 mol) of acetic anhydride and 42.97 g (0.5433 mol) of pyridine were added, followed by stirring at 90 to 100°C for 3 hours.

After the stirring was completed, the reaction mixture was cooled to room temperature, the cooled mixture was added to 7.094 kg of methanol, and the resulting slurry was stirred for 30 minutes. And the filtrate was collect|recovered by filtration. Thereafter, for purification, the obtained filtrate was added again to 7.094 kg of methanol to obtain a slurry, followed by stirring and filtration in the same manner. And again, for purification, addition of the filtrate to methanol, stirring, and filtration were performed again.

Finally, the obtained filtrate was dried at 100°C under reduced pressure for 8 hours to obtain 76 g of the target polyimide A1 (yield: 76%, Mw: 59,302, Mn: 25,923).

[Synthesis Example 2]

115 g (0.3591 mol) of TFMB was put into a 2,000 mL 3-neck flask equipped with a nitrogen inlet/outlet and a mechanical stirrer. Immediately thereafter, 468.9 g of γ-butyrolactone (GBL) was added, and stirring was started. After the diamine (TFMB) was completely dissolved in the solvent, 71.88 g (0.2872 mol) of BODA was added, and the mixture was stirred at 70° C. under a nitrogen atmosphere for 3 hours. Subsequently, the reaction mixture was cooled to 50° C., 14.08 g (0.071 mol) of CBDA was added thereto, and the mixture was stirred for another 2 hours. Thereafter, the reaction mixture was cooled to room temperature to maintain the temperature, and again stirred overnight under a nitrogen atmosphere. And GBL was added to the reaction mixture, and it diluted so that the density|concentration of solid content (concentration of components other than an organic solvent) might be 5 mass %.

To the diluted reaction mixture, 146.65 g (1.436 mol) of acetic anhydride and 85.21 g (1.077 mol) of pyridine were added, followed by stirring at 90 to 100°C for 3 hours.

After completion of the stirring, the reaction mixture was cooled to room temperature, the cooled mixture was added to 2.5 kg of methanol, and the resulting slurry was stirred for 30 minutes. And the filtrate was collect|recovered by filtration. Thereafter, for purification, the obtained filtrate was added again to 2.5 kg of methanol to obtain a slurry, followed by stirring and filtration in the same manner. And again, for purification, addition of the filtrate to 2.5 kg of methanol, stirring, and filtration were performed again.

Finally, the obtained filtrate was dried in a vacuum oven at 120° C. for 8 hours to obtain 153 g of the target polyimide A2 (yield: 76.5%, Mn: 44,460, Mw: 96,641).

The said polyimide A2 was melt|dissolved in GBL, and the obtained solution was filtered under pressure slowly using a 5 micrometer filter, and the solution (polyimide A2 solution) whose density|concentration of solid content is 12 mass % was prepared.

[Synthesis Example 3]

16.9 g (0.052 mol) of TFMB and 1.598 g (0.006 mol) of TMDA were put into a 250 mL 3-neck flask having a nitrogen inlet/outlet and a mechanical stirrer attached. Immediately thereafter, 124.46 g of γ-butyrolactone (GBL) was added, and stirring was started. After diamine (TFMB and TMDA) was completely dissolved in the solvent, 6.725 g (0.03 mol) of TCA was added, and the mixture was stirred at 100° C. for 5 hours under a nitrogen atmosphere. Subsequently, the reaction mixture was cooled to 50° C., 5.883 g (0.03 mol) of CBDA was added thereto, and the mixture was stirred for another 3 hours. Thereafter, the reaction mixture was cooled to room temperature to maintain the temperature, and again stirred overnight under a nitrogen atmosphere. And GBL was added to the reaction mixture, and it diluted so that the density|concentration of solid content (concentration of components other than an organic solvent) might become 4 mass %.

To the diluted reaction mixture, 24.5 g (0.24 mol) of acetic anhydride and 14.23 g (0.18 mol) of pyridine were added, followed by stirring at 60-70°C for 6 hours.

After the stirring was completed, the reaction mixture was cooled to room temperature, the cooled mixture was added to 0.7 kg of methanol, and the resulting slurry was stirred for 30 minutes. And the filtrate was collect|recovered by filtration. Thereafter, for purification, the obtained filtrate was added to 0.7 kg of methanol again to obtain a slurry, followed by stirring and filtration in the same manner. And again, for purification, addition of the filtrate to 0.7 kg of methanol, stirring, and filtration were performed again.

Finally, the obtained filtrate was dried in a vacuum oven at 120° C. for 8 hours to obtain 24.26 g of the target polyimide B (yield: 78%, Mn: 65,425, Mw: 138,024).

The polyimide B was dissolved in GBL, and the obtained solution was filtered under pressure slowly using a 5 µm filter to prepare a solution (polyimide B solution) having a solid content of 11.17% by mass.

[Synthesis Example 4]

25.61 g (0.08 mol) of TFMB was added into a 100 mL 3-neck flask having a nitrogen inlet/outlet and equipped with a mechanical stirrer and a cooler. Immediately thereafter, 173.86 g of γ-butyrolactone (GBL) was added, and stirring was started. After diamine (TFMB) was completely dissolved in the solvent, 10 g (0.04 mol) of BODAxx and 7.84 g (0.04 mol) of CBDA were added, and the mixture was heated to 140° C. under a nitrogen atmosphere. Then, 1.739 g of 1-ethylpiperidine was added to the reaction solution, and the mixture was heated and stirred at 210° C. for 4.5 hours under a nitrogen atmosphere.

The reaction mixture was added to 0.9 kg of methanol, and the resulting slurry was stirred for 30 minutes. And the filtrate was collect|recovered by filtration. Thereafter, for purification, the obtained filtrate was added again to 0.9 kg of methanol to obtain a slurry, followed by stirring and filtration in the same manner. And again, for purification, addition of the filtrate to 0.9 kg of methanol, stirring, and filtration were performed again.

Finally, the obtained filtrate was dried in a vacuum oven at 120° C. for 8 hours to obtain 31.16 g of the target polyimide C (yield: 74%, Mn: 40,465, Mw: 281,382).

The polyimide C was dissolved in GBL, and the obtained solution was filtered under pressure slowly using a 5 µm filter to prepare a solution (polyimide C solution) having a solid content of 13.5% by mass.

[3] Preparation of thin film composition for substrate (1)

[Example 1]

At room temperature, 3 g of polyimide A1 was dissolved in 22 g of DMAc to prepare a polyimide solution, and the resulting solution was filtered under pressure using a 5 μm filter slowly. Then, after adding 6.67 g of IPA-ST silica sol to the filtrate and stirring for 30 minutes, the stirred mixture was left to stand overnight to obtain a resin composition.

[Examples 2-3]

The same method as in Example 1, except that 6.67 g of GBL-ST silica sol (Example 2) and 10.00 g of DMAC-ST silica sol (Example 3) were used instead of 6.67 g of IPA-ST silica sol, respectively. to obtain a resin composition.

[Example 4]

A resin composition was obtained in the same manner as in Example 1, except that 22 g of NMP was used instead of 22 g of DMAc.

[Examples 5-6]

A resin composition was obtained in the same manner as in Example 2, except that 22 g of NMP (Example 5) and 22 g of GBL (Example 6) were used instead of 22 g of DMAc, respectively.

[Example 7]

A resin composition was obtained in the same manner as in Example 2, except that the amount of GBL-ST silica sol used was 2.5 g.

[Examples 8 to 9]

A resin composition was obtained in the same manner as in Example 7, except that 22 g of NMP (Example 8) and 22 g of GBL (Example 9) were used instead of 22 g of DMAc, respectively.

[Example 10]

At room temperature, 3 g of polyimide A1 was dissolved in 22 g of GBL to prepare a polyimide solution, and the resulting solution was filtered under pressure using a 5 µm filter slowly. Then, after adding 6.67 g of GBL-ST silica sol to the filtrate and stirring for 30 minutes, oxybis((3-aminopropyl)dimethylsilane) as a catalyst is added thereto so that 0.5% by mass based on the total mass of the composition. The mixture was stirred for 3 minutes to obtain a resin composition.

[Examples 11-12]

Instead of GBL-ST silica sol 6.67g, respectively, GBL-UP silica sol 10g (Example 11), GBL-M silica sol 6.67g (Example 12), except for using the same method as in Example 6 A resin composition was obtained.

[Example 13]

At room temperature, 3 g of polyimide A1 was dissolved in 22 g of GBL to prepare a polyimide solution, and the resulting solution was filtered under pressure using a 5 µm filter slowly. Then, after adding 3.33 g of GBL-ST silica sol and 5 g of GBL-UP silica sol to the filtrate and stirring for 30 minutes, the stirred mixture was left to stand overnight to obtain a resin composition.

[Examples 14-15]

The resin composition in the same manner as in Example 13, except that instead of 5 g of GBL-UP silica sol, 3.33 g of GBL-M silica sol (Example 14) and 4 g of GBL-S silica sol (Example 15) were used, respectively. got

[4] Preparation of thin resin film (1)

[Example 16]

The resin composition obtained in Example 1 was applied to a glass substrate, and the coating film was sequentially heated at 50° C. for 30 minutes, 140° C. for 30 minutes, and 200° C. for 60 minutes to obtain a resin thin film. On the other hand, three ovens previously set to a desired temperature were used for heating.

The obtained resin thin film was peeled off by mechanical cutting, and it used for subsequent evaluation.

[Examples 17-30]

A resin thin film was obtained in the same manner as in Example 16, except that the resin composition obtained in Examples 2 to 15 was used instead of the resin composition obtained in Example 1.

[5] Evaluation of thin resin films (1)

Regarding the heat resistance and optical properties of each resin thin film produced in the above-mentioned order, that is, coefficient of linear expansion (50 to 200 ° C), 5% weight loss temperature, light transmittance and CIE b value (yellow evaluation), and retardation, Each was evaluated according to the above sequence. A result is shown in Table 1.

As shown in Table 1, the resin thin film of the present invention has a low coefficient of linear expansion [ppm/° C.] (50 to 200° C.), and a high light transmittance [%] at 400 nm and 550 nm after curing, and further CIE It was confirmed that the yellowness indicated by the b* value was small and the retardation was suppressed to a low value. In addition, there was a tendency that the higher the content of the silica sol, the lower the coefficient of linear expansion and the higher the light transmittance.

In addition, all of the resin thin films of the present invention obtained in Examples 16 to 30 were not broken even when they were bent at an acute angle (about 30 degrees) by holding them with both hands, and had high flexibility required for a flexible display substrate.

[6] Preparation of thin film composition for substrate (2)

[Example 31]

At room temperature, 4.457 g of the polyimide A2 solution prepared in Synthesis Example 2 (polyimide A2 solid content: 0.534 g) was slowly filtered under pressure using a 5 μm filter. Then, to the filtrate, 1.426 g of GBL-ZL silicasol and 0.059 g of γ-butyrolactone (GBL) were added and stirred for 30 minutes, and then the stirred mixture was left to stand overnight to obtain a resin composition.

[Example 32-Example 38]

Example 31, except that the addition amount of the polyimide A2 solution prepared in Synthesis Example 2 (the numerical value in the table is the amount used as a solution), the type and amount of silica sol, and the amount of γ-butyrolactone added in Table 2 below A resin composition was obtained in the same manner as described above.

[Example 39]

At room temperature, 2.146 g of the polyimide B solution prepared in Synthesis Example 3 (polyimide B solid content: 0.239 g) was filtered under pressure slowly using a 5 μm filter. Then, 0.639 g of GBL-ZL silica sol and 0.544 g of γ-butyrolactone (GBL) were added to the filtrate and stirred for 30 minutes, and then the stirred mixture was left to stand overnight to obtain a resin composition.

[Example 40-Example 48]

Example 39, except that the addition amount of the polyimide B solution prepared in Synthesis Example 3 (the numerical values in the table are the amount used as a solution), the type and amount of silica sol, and the amount of γ-butyrolactone added in Table 3 below A resin composition was obtained in the same manner as

[Example 49]

At room temperature, 2.5147 g of the polyimide C solution prepared in Synthesis Example 4 (polyimide C solid content: 0.339 g) was filtered under pressure slowly using a 5 μm filter. Then, 0.905 g of GBL-ZL silica sol and 0.165 g of GBL were added to the filtrate and stirred for 30 minutes, and then the stirred mixture was left to stand overnight to obtain a resin composition.

[Example 50-Example 64]

Example 49, except that the addition amount of the polyimide C solution prepared in Synthesis Example 4 (the numerical values in the table are the amount used as a solution), the type and amount of silica sol, and the amount of γ-butyrolactone added in Table 4 below A resin composition was obtained in the same manner as

[7] Preparation of thin resin film (2)

The resin composition obtained in Example 31 was applied to a glass substrate, and the coating film was sequentially heated at 50° C. for 30 minutes, 140° C. for 30 minutes, 220° C. for 60 minutes, and 280° C. for 60 minutes to obtain a resin thin film. On the other hand, four ovens previously set to a desired temperature were used for heating.

The obtained resin thin film was peeled off by mechanical cutting, and it used for subsequent evaluation.

In addition, each resin thin film was obtained in the same manner as above, except that the resin composition obtained in Examples 32 to 64 was used instead of the resin composition obtained in Example 31.

[8] Evaluation of thin resin films (2)

The heat resistance and optical properties of each resin thin film produced in the above-mentioned order, that is, the coefficient of linear expansion, 5% weight loss temperature, light transmittance and CIE b value (yellow evaluation), and retardation are evaluated according to the above procedure, respectively. did The results are shown in Tables 2 to 4.

As shown in Tables 2 to 4, the resin thin film of the present invention has a low coefficient of linear expansion [ppm/°C] (particularly 50 to 200°C), and the light transmittance [%] at 400 nm and 550 nm after curing Furthermore, it was confirmed that the yellowness indicated by the CIE b* value was small, the retardation was suppressed to a low value, and the value Δn of the birefringence was also very low. In addition, there was a tendency that the coefficient of linear expansion was lower as the content of the silica sol increased.

In addition, all of the resin thin films of the present invention obtained as described above had high flexibility required for flexible display substrates without being broken even when they were bent at an acute angle (about 30 degrees) by holding them with both hands.

Claims (14)

A method for producing a resin thin film, comprising:
Imidation of a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride represented by Formula (C1) with a diamine component containing a fluorinated aromatic diamine represented by Formula (A1) polyimide obtained by
Silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method, and
organic solvent
A method for using a composition for forming a resin thin film comprising a.

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-4), (X-6) and (X-7).

(In the formula, * represents the number of bonds.)]

(In the formula, B ² represents a divalent group represented by the formula (Y-12).)

(In the formula, * represents the number of bonds.)
delete delete According to claim 1,
The method, wherein the polyimide further contains a monomer unit represented by the formula (2).

According to claim 1,
The mass ratio of the polyimide to the silicon dioxide particles is 7:3 to 3:7, the method.
According to claim 1,
The method, wherein the silicon dioxide particles have an average particle diameter calculated from a specific surface area value measured by a nitrogen adsorption method, 60 nm or less.
A resin thin film produced by the method according to any one of claims 1 to 6.
Imidation of a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride represented by Formula (C1) with a diamine component containing a fluorinated aromatic diamine represented by Formula (A1) polyimide obtained by
Silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method, and
organic solvent
A composition for forming a resin thin film comprising a.

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-4), (X-6) and (X-7).

(In the formula, * represents the number of bonds.)]

(In the formula, B ² represents a divalent group represented by the formula (Y-12).)

(In the formula, * represents the number of bonds.)
delete delete 9. The method of claim 8,
The said polyimide, the composition for resin thin film formation which further contains the monomer unit represented by Formula (2).

9. The method of claim 8,
The mass ratio of the polyimide and the silicon dioxide particles is 7:3 to 3:7, the composition for forming a resin thin film.
9. The method of claim 8,
The silicon dioxide particles have an average particle diameter calculated from a specific surface area value measured by a nitrogen adsorption method, 60 nm or less, a composition for forming a resin thin film.
As a method of reducing the retardation of the resin thin film,
Imidization of a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing a alicyclic tetracarboxylic dianhydride represented by Formula (C1) with a diamine component containing a fluorinated aromatic diamine represented by Formula (A1) obtained polyimide,
Silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method, and
organic solvent
A method for forming a resin thin film using a composition for forming a resin thin film comprising a.

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-4), (X-6) and (X-7).

(In the formula, * represents the number of bonds.)]

(In the formula, B ² represents a divalent group represented by the formula (Y-12).)

(In the formula, * represents the number of bonds.)