CN110922753A

CN110922753A - Composition for forming optical film

Info

Publication number: CN110922753A
Application number: CN201910879876.0A
Authority: CN
Inventors: 宫本皓史; 池内淳一
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2018-09-20
Filing date: 2019-09-17
Publication date: 2020-03-27

Abstract

The present invention addresses the problem of providing a composition having excellent storage stability. The solution of the present invention is a composition comprising a transparent polyamideimide resin having at least a structural unit derived from a diamine compound and a solvent represented by the formula (X)A structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound. In the formula (X), R^a1And R^a2Independently represent an alkyl group having 1 to 6 carbon atoms, R^a3Represents an alkyl group having 2 to 6 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms.

Description

Composition for forming optical film

Technical Field

The present invention relates to a composition capable of forming an optical film that can be used as a front panel of an image display device or the like, and to the optical film.

Background

Image display devices such as liquid crystal display devices and organic EL display devices have been widely and flexibly used for various applications such as mobile phones and smartwatches. Glass has been used as a front panel of such an image display device, but glass is very rigid and easily broken, and therefore, it is difficult to use the glass as a front panel material of, for example, a flexible display or the like. As one of materials replacing glass, polyamide-imide resin is known, and an optical film using the resin is studied (for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2015-521687

Disclosure of Invention

Problems to be solved by the invention

Such an optical film is obtained by applying a composition (resin varnish) prepared by dissolving a polyamideimide resin in a solvent to a support material and then drying the applied composition. In particular, when the production scale of the optical film becomes large, the prepared composition may be temporarily stored and then applied to a support material. However, as a result of the research by the present inventors, it was found that, depending on the kind of solvent contained in the composition, there were the following cases: the polyamide-imide resin or the like precipitates or gels during storage, and thus the optical properties of the obtained optical film are degraded.

Accordingly, an object of the present invention is to provide a composition having excellent storage stability, and an optical film formed from the composition.

Means for solving the problems

The present inventors have intensively studied to solve the above problems, and as a result, they have found that the above problems can be solved by using a solvent represented by the formula (X) as a solvent in a composition comprising a transparent polyamideimide resin having at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound, and the present invention has been completed. That is, the present invention includes the following aspects.

[1] A composition comprising a transparent polyamideimide resin having at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound, and a solvent represented by formula (X).

[ in the formula (X), R^a1And R^a2Independently represent an alkyl group having 1 to 6 carbon atoms, R^a3Represents an alkyl group having 2 to 6 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms]

[2] The composition according to [1], wherein the transparent polyamideimide resin has a weight average molecular weight of 150,000 or more in terms of polystyrene.

[3] The composition according to [1] or [2], wherein the transparent polyamideimide resin has an imidization rate of 90% or more.

[4] The composition according to any one of [1] to [3], wherein the content of the transparent polyamideimide resin is 5% by mass or more based on the mass of the composition.

[5] The composition according to any one of [1] to [4], which has a viscosity of 5,000 to 100,000 mPas at 25 ℃ measured according to JIS K5600-2-3.

[6] An optical film comprising the composition according to any one of [1] to [5 ].

[7] A flexible display device comprising the optical film according to [6 ].

[8] The flexible display device according to [7], further comprising a touch sensor.

[9] The flexible display device according to [7] or [8], further comprising a polarizing plate.

ADVANTAGEOUS EFFECTS OF INVENTION

The composition of the present invention has excellent storage stability.

Detailed Description

[ composition ]

The composition of the present invention comprises a transparent polyamideimide resin having at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound, and a solvent represented by formula (X).

In the present specification, the solvent represented by the formula (X) may be referred to as a solvent (X). In addition, the composition of the present invention may also be referred to as a resin varnish.

The composition of the present invention comprises the transparent polyamideimide resin and the solvent (X), and therefore, it has excellent storage stability and can effectively prevent precipitation or gelation of the transparent polyamideimide resin or the like during storage. This is presumed to be because R is particularly caused by the solvent (X) having a prescribed structure^a3The alkyl group or alkoxyalkyl group of (2) has 2 or more carbon atoms, so that hydrophobicity can be improved and decrease in solubility due to absorption of external moisture can be effectively suppressed. Therefore, the composition of the present invention can form an optical film having excellent optical characteristics, for example, an optical film exhibiting excellent optical characteristics even after being stored for a long time.

< solvent >

The solvent contained in the composition of the present invention is represented by formula (X).

In the formula (X), R^a1And R^a2The alkyl group having 1 to 6 carbon atoms independently represents, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 2-ethylpropyl group, or an n-hexyl group. Among these, an alkyl group having 1 to 4 carbon atoms is preferable, a methyl group or an ethyl group is more preferable, and a methyl group is even more preferable, from the viewpoint of improving the storage stability of the composition, reducing the viscosity, and improving the optical properties of the resulting film.

In the formula (X), R^a3Represents an alkyl group having 2 to 6 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms. Examples of the alkyl group having 2 to 6 carbon atoms include ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, 2-methylbutyl group, 3-methylbutyl group, 2-ethylpropyl group, and n-hexyl group. Examples of the alkoxyalkyl group having 2 to 12 carbon atoms include a methoxymethyl group, a methoxyethyl group, a methoxypropyl group, a methoxybutyl group, a methoxypentyl group, a 1-ethoxyethyl group, a 2-ethoxyethyl group, a 1-methyl-2-ethoxyethyl group, a 1-ethoxy-1-methylethyl group, a 1- (1-methylethoxy) -1-methylethyl group, a 2-ethoxy-1-methylethyl group, a 1-ethoxypropyl group, a 2-ethoxypropyl group, a 3-ethoxypropyl group, a 1- (1-methylethoxy) propyl group, a 2- (1-methylethoxy) propyl group, a 1-isopropoxypropyl group, a 1-ethoxypropyl group, a 1-, 2-isopropoxypropyl, 1-isopropoxy-1-methylethyl, 2-isopropoxy-1-methylethyl, butoxymethyl, octyloxypropyl, 3- (2-ethylhexyloxy) propyl and the like. Among these, from the viewpoint of improving the storage stability of the composition, reducing the viscosity, and improving the optical properties of the obtained film, an alkyl group having 2 to 4 carbon atoms or an alkoxyalkyl group having 2 to 6 carbon atoms is preferable, an alkyl group having 2 to 4 carbon atoms or an alkoxyalkyl group having 2 to 4 carbon atoms is more preferable, and an ethyl group, a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, or an ethoxyethyl group is further preferable. The solvent (X) may be used alone or in combination of two or more.

Specific examples of the solvent (X) include N, N-Dimethylpropionamide (DMPA), N-dimethylbutanamide, N, 2-trimethylpropionamide, N, 3-trimethylbutyramide, N, 2, 2-tetramethylpropionamide, N-dimethylpentanamide, N-diethylpropionamide, N-methylethylpropionamide, 3-methoxy-N, N-dimethylpropionamide (MMPA), 3-methoxy-N, N-diethylpropionamide, 3-methoxy-N, N-methylethylpropionamide, 3-ethoxy-N, N-dimethylpropionamide, 3-ethoxy-N, N-diethylpropionamide, 3-ethoxy-N, n-methylethylpropionamide, 2-methoxy-N, N-dimethylacetamide, 2-methoxy-N, N-diethylacetamide, 2-methoxy-N, N-methylethylacetamide, 2-ethoxy-N, N-dimethylacetamide, 2-ethoxy-N, N-diethylacetamide, 2-ethoxy-N, N-methylethylacetamide, and the like. These solvents (X) may be used alone or in combination of two or more.

The solvent in the composition of the present invention may be used in combination with the solvent (X) and other solvents. Examples of the solvent other than (X) include alcohol-based solvents, ester-based solvents, ether-based solvents, ketone-based solvents, aromatic-based solvents, lactone-based solvents, and specifically include alcohol-based solvents such as methanol, ethanol, isopropanol, n-propanol, and n-butanol; ester-based solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ether solvents such as ether, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; aromatic solvents such as toluene, o-xylene, m-xylene, p-xylene, o-cresol, m-cresol, and p-cresol; lactone solvents such as γ -butyrolactone, etc., and in view of the storage stability of the composition, preferable examples thereof include ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone, aromatic solvents such as o-cresol, m-cresol, and p-cresol, and lactone solvents such as γ -butyrolactone, and more preferable examples thereof include butyl acetate, cyclopentanone, cyclohexanone, and γ -butyrolactone.

The content of the solvent (X) in the composition of the present invention is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, and particularly preferably 50% by mass or more, based on the total mass of the solvents contained in the composition. When the content of the solvent (X) is within the above range, the composition is advantageously improved in storage stability, reduced in viscosity, and improved in optical properties of the obtained film. The upper limit of the content of the solvent (X) is 100 mass% or less.

In the composition of the present invention, the content of the solvent is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, preferably 95% by mass or less, more preferably 93% by mass or less, and further preferably 90% by mass or less, based on the mass of the composition. When the content of the solvent is in the above range, the storage stability of the composition is easily improved, and the viscosity suitable for forming a film of the composition is easily obtained, so that the workability is improved.

< transparent polyamideimide resin >

The transparent polyamideimide resin contained in the composition of the present invention is a polymer containing both a repeating structural unit containing an imide group and a repeating structural unit containing an amide group, and has at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound. The polyamide-imide resin is obtained by copolymerizing a carboxylic acid compound containing a dicarboxylic acid compound and a tetracarboxylic acid compound, and a diamine compound.

In a preferred embodiment of the present invention, the transparent polyamideimide resin according to the present invention has a structural unit represented by formula (1) and a structural unit represented by formula (2).

The structural unit represented by formula (1) is a structural unit formed by reacting a tetracarboxylic acid compound with a diamine compound, and the structural unit represented by formula (2) is a structural unit formed by reacting a dicarboxylic acid compound with a diamine compound.

In the formula (2), Z is independently a 2-valent organic group, preferably a 4-40 carbon organic group which may be substituted by a 1-8 carbon hydrocarbon group or a 1-8 fluorine-substituted hydrocarbon group, and more preferably a 2-valent organic group having a cyclic structure and a 4-40 carbon atom which may be substituted by a 1-8 carbon hydrocarbon group or a 1-8 fluorine-substituted hydrocarbon group. Examples of the cyclic structure include alicyclic, aromatic ring, and heterocyclic structure. Examples of the organic group of Z include a group obtained by substituting hydrogen atoms for non-adjacent 2 of chemical bonds of the groups represented by the formula (20), the formula (21), the formula (22), the formula (23), the formula (24), the formula (25), the formula (26), the formula (27), the formula (28) and the formula (29) which will be described later, and a 2-valent chain hydrocarbon group having 6 or less carbon atoms, and examples of the heterocyclic structure of Z include a group having a thiophene ring skeleton. From the viewpoint of easily improving the storage stability of the composition and easily suppressing the yellowness (lowering the YI value) of the optical film obtained, the groups represented by formulae (20) to (27) and the group having a thiophene ring skeleton are preferable.

In one embodiment of the present invention, the polyimide-based resin may include a plurality of Z, and the plurality of Z may be the same or different. In particular, from the viewpoint of easily improving the storage stability of the composition, and easily exhibiting high surface hardness and excellent optical characteristics of the optical film, it is preferable that at least a part of Z is represented by formula (3).

[ in the formula (3), R¹～R⁸Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, R¹～R⁸The hydrogen atoms contained in (a) may be substituted independently of each other by halogen atoms,

a independently of each other represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃) -、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-, -S-, -CO-or-N(R⁹)-，R⁹Represents a hydrogen atom, a C1-valent hydrocarbon group which may be substituted with a halogen atom and has 1 to 12 carbon atoms,

m is an integer of 0 to 4,

represents a chemical bond ]

In the formula (3), A independently represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、 -CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-, -S-, -CO-or-N (R)⁹) From the viewpoint of the storage stability of the composition and the bending resistance of the optical film to be obtained, the compound preferably represents-O-or-S-, and more preferably represents-O-. R¹、R²、R³、R⁴、R⁵、 R⁶、R⁷、R⁸Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 2-ethylpropyl group, and an n-hexyl group. Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, a butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a cyclohexyloxy group, and the like. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group. From the viewpoint of storage stability of the composition and surface hardness and flexibility of the optical film obtained therefrom, R¹～R⁸Independently of each other, the alkyl group preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and still more preferably represents a hydrogen atom. Here, R¹～R⁸The hydrogen atoms contained in (a) may be substituted by halogen atoms independently of each other. R⁹Represents a hydrogen atom, a C1-valent hydrocarbon group which may be substituted with a halogen atom and has 1 to 12 carbon atoms.

In the formula (3), when m is an integer in the range of 0 to 4 and m is in the above range, the storage stability of the composition and the bending resistance and elastic modulus of the optical film obtained are easily improved. In the formula (3), when m is preferably an integer in the range of 0 to 3, more preferably an integer in the range of 0 to 2, and further preferably 0 or 1, and m is in the above range, the storage stability of the composition, and the bending resistance and elastic modulus of the optical film to be obtained are easily improved. Z may contain 1 or 2 or more groups represented by formula (3), and in particular, may contain 2 or more groups having different m values, preferably 2 groups having different m values, from the viewpoint of improving the storage stability of the composition, improving the elastic modulus and bending resistance of the optical film to be obtained, and reducing the yellowness (YI value). In this case, from the viewpoint of improving the storage stability of the composition and easily exhibiting a high elastic modulus, high bending resistance and a low yellowness (YI value) of the obtained optical film, it is preferable that both groups having m of 0 and 1 are contained.

Preferred examples of the group represented by formula (3) include m ═ 0 and R⁵～R⁸A group which is a hydrogen atom, and which may be combined with other groups to constitute a resin.

Examples of the combinable group include groups represented by the formula (3').

In this case, the optical film is advantageous in view of the storage stability of the composition, and the obtained optical film tends to have high surface hardness and high bending resistance and to decrease the yellowness.

In a preferred embodiment of the present invention, the group represented by formula (3) is preferably 20 mol% or more, more preferably 30 mol% or more, further preferably 40 mol% or more, particularly preferably 50 mol% or more, most preferably 60 mol% or more, preferably 90 mol% or less, more preferably 85 mol% or less, and further preferably 80 mol% or less, relative to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) of the polyamideimide resin. When the group represented by formula (3) is not less than the above-mentioned lower limit relative to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) in the polyamideimide resin, the storage stability of the composition is easily improved. In addition, the obtained optical film easily exhibits high surface hardness, and also easily exhibits excellent bending resistance and elastic modulus. When the group represented by formula (3) is not more than the above upper limit relative to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) in the polyamideimide resin, an increase in viscosity of the composition due to hydrogen bonding between amide bonds derived from formula (3) can be suppressed, and the storage stability and handling properties of the composition can be easily improved.

In a preferred embodiment of the present invention, the group represented by formula (3) in which m is 1 to 4 is preferably 3 mol% or more, more preferably 5 mol% or more, further preferably 7 mol% or more, particularly preferably 9 mol% or more, preferably 90 mol% or less, more preferably 70 mol% or less, further preferably 50 mol% or less, and particularly preferably 30 mol% or less, relative to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) of the polyamideimide resin. When the group represented by formula (3) wherein m is 1 to 4 is equal to or more than the lower limit described above with respect to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) in the polyamideimide resin, the storage stability of the composition is easily improved. In addition, the obtained optical film easily exhibits high surface hardness and high bending resistance. When the group represented by formula (3) wherein m is 1 to 4 is not more than the upper limit described above relative to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) in the polyamideimide resin, the increase in viscosity of the composition due to hydrogen bonding between amide bonds derived from formula (3) can be suppressed, and the storage stability and handling properties of the composition can be improved. The content of the group represented by the formula (3) can be determined, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In a preferred embodiment of the present invention, preferably 30 mol% or more, more preferably 50 mol% or more, and still more preferably 70 mol% or more of Z in the polyamideimide resin is represented by formula (3) when m is 0 to 4. When the lower limit or more of Z in the polyamideimide resin is represented by formula (3) in which m is 0 to 4, the storage stability of the composition is easily improved. In addition, the obtained optical film easily exhibits high surface hardness and excellent bending resistance and elastic modulus. Further, it is preferable that 100 mol% or less of Z in the polyamideimide resin is represented by the formula (3) when m is 0 to 4. When the above upper limit or less of Z in the polyamideimide resin is represented by formula (3) in the case where m is 0 to 4, the viscosity of the composition can be prevented from increasing due to hydrogen bonds between amide bonds derived from formula (3) in the case where m is 0 to 4, and the storage stability and handling properties of the composition can be improved.

In a preferred embodiment of the present invention, preferably 5 mol% or more, more preferably 8 mol% or more, still more preferably 10 mol% or more, and particularly preferably 12 mol% or more of Z in the polyamideimide resin is represented by formula (3) in the case where m is 1 to 4. When the lower limit or more of Z in the polyamideimide resin is represented by formula (3) in which m is 1 to 4, the storage stability of the composition is easily improved. In addition, the obtained optical film easily exhibits high surface hardness and excellent bending resistance and elastic modulus. In addition, in the polyamideimide resin, preferably 90 mol% or less, more preferably 70 mol% or less, further preferably 50 mol% or less, and particularly preferably 30 mol% or less of Z is represented by formula (3) in the case where m is 1 to 4. When the upper limit or less of Z of the polyamideimide resin is represented by formula (3) in which m is 1 to 4, the viscosity of the composition can be prevented from increasing due to hydrogen bonds between amide bonds derived from formula (3) in which m is 1 to 4, and the storage stability and handling properties of the composition can be improved. The ratio of the group represented by the formula (3) in the polyamideimide resin can be used, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In the formulae (1) and (2), X independently represents a 2-valent organic group, preferably a 2-valent organic group having 4 to 40 carbon atoms, and more preferably a 2-valent organic group having 4 to 40 carbon atoms and having a cyclic structure. Examples of the cyclic structure include alicyclic, aromatic ring, and heterocyclic structure. The organic group may have hydrogen atoms substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and in this case, the number of carbon atoms in the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8. The polyamideimide resin according to one embodiment of the present invention may include a plurality of xs, and the plurality of xs may be the same or different from each other. Examples of X include: a group represented by formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) or formula (18); a group obtained by substituting a hydrogen atom in the groups represented by the formulae (10) to (18) with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms.

In the formulae (10) to (18), represents a bond,

V¹、V²and V³Independently of each other, represents a single bond, -O-, -S-, -CH₂-、-CH₂-CH₂-、 -CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-, -CO-or-NQ. Wherein Q represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom.

1 example is: v¹And V³Is a single bond, -O-or-S-, and V²is-CH₂-、-C (CH₃)₂-、-C(CF₃)₂-or-SO₂-。V¹And V²Bonding position with respect to each ring, and V²And V³The bonding position to each ring is preferably meta-or para-position independently of each other, and more preferably para-position.

Among the groups represented by formulae (10) to (18), the groups represented by formulae (13), (14), (15), (16) and (17) are preferable, and the groups represented by formulae (14), (15) and (16) are more preferable, from the viewpoint of improving the storage stability of the composition and easily improving the surface hardness and bending resistance of the optical film obtained. In addition, V is considered to improve the storage stability of the composition and to improve the surface hardness and flexibility of the optical film obtained¹、V²And V³Independently of one another, are preferably single bonds, -O-or-S-, more preferably single bonds or-O-.

In a preferred embodiment of the present invention, at least a part of the plurality of xs in the formulae (1) and (2) is a group represented by the formula (4).

[ in the formula (4), R¹⁰～R¹⁷Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹⁰～ R¹⁷The hydrogen atoms contained in (A) may be substituted independently of each other by halogen atoms, representing a chemical bond]

When at least a part of the plurality of xs in the formulae (1) and (2) is a group represented by the formula (4), the storage stability of the composition is easily improved, and the obtained optical film easily exhibits high surface hardness and high transparency.

In the formula (4), R¹⁰、R¹¹、R¹²、R¹³、R¹⁴、R¹⁵、R¹⁶And R¹⁷Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms in the formula (3). R¹⁰～R¹⁷Independently of each other, preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R¹⁰～R¹⁷The hydrogen atoms contained in (a) may be substituted by halogen atoms independently of each other. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. From the viewpoint of the storage stability of the composition and the surface hardness, transparency and bending resistance of the optical film obtained therefrom, R¹⁰～R¹⁷Further preferred are, independently of one another, a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and R is particularly preferred¹⁰、R¹²、R¹³、R¹⁴、 R¹⁵And R¹⁶Is a hydrogen atom, and R¹¹And R¹⁷Is a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and R is particularly preferred¹¹And R¹⁷Is methyl or trifluoromethyl.

In a preferred embodiment of the present invention, the group represented by formula (4) is a group represented by formula (4'),

that is, at least a part of the plurality of xs is a group represented by formula (4'). In this case, the fluorine element-containing skeleton makes it easy to improve the solubility of the polyamideimide resin in a solvent, to improve the storage stability of the composition, to reduce the viscosity, and to improve the workability. Further, the optical properties of the optical film obtained are also easily improved by the skeleton containing a fluorine element.

In a preferred embodiment of the present invention, preferably 30 mol% or more, more preferably 50 mol% or more, and still more preferably 70 mol% or more of X in the polyamideimide resin is represented by formula (4), particularly formula (4'). When X in the above range in the polyamideimide resin is represented by formula (4), particularly formula (4'), the solubility of the polyamideimide resin in a solvent is easily improved by the fluorine element-containing skeleton of the obtained optical film, the storage stability of the composition is easily improved, and the viscosity can be reduced and the workability can be easily improved. Further, the optical properties of the optical film obtained are also easily improved by the skeleton containing a fluorine element. In the polyamideimide resin, 100 mol% or less of X is preferably represented by formula (4), particularly formula (4'). X in the above polyamideimide resin may be represented by the formula (4), particularly (4'). The ratio of the group represented by the formula (4) of X in the polyamideimide resin can be used, for example¹H-NMR, orCan be calculated from the charge ratio of the raw materials.

In the formula (1), Y independently represents a 4-valent organic group, preferably a 4-valent organic group having 4 to 40 carbon atoms, and more preferably a 4-valent organic group having 4 to 40 carbon atoms and having a cyclic structure. Examples of the cyclic structure include alicyclic, aromatic ring, and heterocyclic structure. The organic group is an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and in this case, the number of carbon atoms in the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8. The polyamideimide resin according to one embodiment of the present invention may include a plurality of Y, and the plurality of Y may be the same or different. Examples of Y include groups represented by the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula (29); a group obtained by substituting a hydrogen atom in the group represented by the formulae (20) to (29) with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having a valence of 4 and 6 or less carbon atoms.

In the formulae (20) to (29),

the symbol represents a chemical bond,

W¹represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-Ar-、-SO₂-、-CO-、-O-Ar-O-、-Ar-O-Ar-、-Ar-CH₂-Ar-、-Ar-C(CH₃)₂-Ar-or-Ar-SO₂-Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom, and specific examples thereof include phenylene groups.

Among the groups represented by formulae (20) to (29), the group represented by formula (26), formula (28) or formula (29) is preferable, and the group represented by formula (26) is more preferable, from the viewpoint of the storage stability of the composition and the surface hardness and bending resistance of the optical film to be obtained. Further, the storage stability of the composition, and the obtainedW is a group of optical films having surface hardness, bending resistance and easy yellow color suppression¹Independently of one another, are preferably single bonds, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-or-C (CF)₃)₂-, more preferably a single bond, -O-, -CH₂-、-CH(CH₃)-、-C(CH₃)₂-or-C (CF)₃)₂-is more preferably a single bond, -C (CH)₃)₂-or-C (CF)₃)₂-。

In a preferred embodiment of the present invention, at least a part of Y in formula (1) is a group represented by formula (5).

[ in the formula (5), R¹⁸～R²⁵Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹⁸～ R²⁵The hydrogen atoms contained in (a) may be substituted independently of each other by halogen atoms,

represents a chemical bond ]

When at least a part of the plurality of Y in the formula (1) is a group represented by the formula (5), the solubility of the polyamideimide resin in a solvent is easily improved, the storage stability of the composition is easily improved, the viscosity can be reduced, and the workability can be easily improved. In addition, the optical properties of the optical film obtained are easily improved.

In the formula (5), R¹⁸、R¹⁹、R²⁰、R²¹、R²²、R²³、R²⁴、R²⁵Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms in the formula (3)The groups exemplified hereinabove. R¹⁸～R²⁵Independently of each other, preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R¹⁸～R²⁵The hydrogen atoms contained in (a) may be substituted by halogen atoms independently of each other. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. R is a group having a high refractive index, and is easily improved in storage stability of the composition and surface hardness, bending resistance and transparency of the optical film obtained¹⁸～R²⁵Independently of each other, a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group is more preferable, and R is further more preferable¹⁸、R¹⁹、R²⁰、R²³、R²⁴And R²⁵Is a hydrogen atom, and R²¹And R²²Is hydrogen, methyl, fluoro, chloro or trifluoromethyl, particularly preferably R²¹And R²²Is methyl or trifluoromethyl.

In a preferred embodiment of the present invention, the group represented by formula (5) is a group represented by formula (5'),

that is, at least a part of the plurality of Y's is a group represented by formula (5'). In this case, the fluorine element-containing skeleton makes it easy to improve the solubility of the polyamideimide resin in a solvent, to improve the storage stability of the composition, to reduce the viscosity, and to improve the workability. Further, the optical properties of the optical film obtained are easily improved by the skeleton containing a fluorine element.

In a preferred embodiment of the present invention, preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more of Y in the polyamideimide resin is represented by formula (5), particularly formula (5'). When Y in the above range in the polyamideimide resin is represented by the formula (5), particularly the formula (5'), the solubility of the polyamideimide resin in a solvent is easily improved by the fluorine element-containing skeleton, and the group is easily improvedThe storage stability of the compound can be reduced, and the viscosity can be reduced, so that the handling property can be easily improved. Further, the optical properties of the optical film obtained are easily improved by the skeleton containing a fluorine element. Preferably, 100 mol% or less of Y in the polyamideimide resin is represented by formula (5), particularly formula (5'). Y in the above polyamideimide resin may be represented by formula (5), particularly (5'). The ratio of the group represented by the formula (5) in Y in the polyamideimide resin can be used, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

The polyamideimide resin may contain a structural unit represented by formula (30) and/or a structural unit represented by formula (31) in addition to the structural units represented by formulae (1) and (2).

In the formula (30), Y¹Independently of one another, are 4-valent organic groups, preferably organic groups in which the hydrogen atoms of the organic groups may be replaced by hydrocarbon groups or fluorine-substituted hydrocarbon groups. As Y¹Examples thereof may include groups represented by the formulae (20), (21), (22), (23), (24), (25), (26), (27), (28) and (29), groups in which a hydrogen atom in the groups represented by the formulae (20) to (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and chain hydrocarbon groups having 4-valent carbon atoms of 6 or less. The polyamideimide resin, which is one embodiment of the present invention, may include a plurality of Y¹Plural number of Y¹May be the same or different from each other.

In the formula (31), Y²Is a 3-valent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y²Examples thereof include a group obtained by replacing any of the chemical bonds of the groups represented by the above-mentioned formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula (29) with a hydrogen atom, and a chain hydrocarbon group having 3-valent carbon atoms of 6 or less. As an embodiment of the inventionThe polyamideimide resin of mode (a) may contain a plurality of Y²Plural number of Y²May be the same or different from each other.

In the formulae (30) and (31), X¹And X²Independently of one another, are 2-valent organic groups, preferably organic groups in which the hydrogen atoms of the organic groups can be replaced by hydrocarbon groups or fluorine-substituted hydrocarbon groups. As X¹And X²Examples of the "substituent" may include groups represented by the above-mentioned formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) and formula (18); a group obtained by substituting a hydrogen atom in the groups represented by the formulae (10) to (18) with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms.

In one embodiment of the present invention, the transparent polyamideimide resin is formed of a structural unit represented by formula (1) and a structural unit represented by formula (2), and a structural unit represented by formula (30) and/or a structural unit represented by formula (31) which may be included. In the transparent polyamideimide resin, the structural unit represented by the formula (1) or (2) is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more, based on the total structural units represented by the formula (1) or (2) and, if necessary, the formula (30) or (31), from the viewpoint of storage stability of the composition, and optical characteristics, surface hardness, and bending resistance of the optical film to be obtained. In the transparent polyamideimide resin, the structural units represented by the formulae (1) and (2) are usually 100% or less based on the total structural units represented by the formulae (1) and (2) and, if necessary, the formulae (30) and (31). The above ratio can be used, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

The weight average molecular weight (Mw) of the transparent polyamideimide resin is preferably 150,000 or more, more preferably 200,000 or more, further preferably 250,000 or more, particularly preferably 300,000 or more, preferably 1,000,000 or less, more preferably 800,000 or less, further preferably 700,000 or less, and particularly preferably 500,000 or less in terms of standard polystyrene. When the Mw of the transparent polyamideimide resin is not less than the above lower limit, the surface hardness and the bending resistance of the optical film to be obtained can be improved. In addition, when the weight average molecular weight of the transparent polyamideimide resin is not more than the upper limit, the solubility of the transparent polyamideimide resin in a solvent is easily improved, so that the storage stability can be improved, and precipitation or gelation of the transparent polyamideimide resin and the like during storage can be prevented. The weight average molecular weight can be determined by GPC measurement and conversion to standard polystyrene, and can be calculated by the method described in examples, for example.

In the transparent polyamideimide resin, the content of the structural unit represented by the formula (2) is preferably 0.1 mol or more, more preferably 0.5 mol or more, further preferably 1.0 mol or more, particularly preferably 1.5 mol or more, preferably 6.0 mol or less, more preferably 5.0 mol or less, further preferably 4.5 mol or less, based on 1 mol of the structural unit represented by the formula (1). When the content of the structural unit represented by the formula (2) is within the above range, the storage stability of the composition can be easily improved.

The imidization ratio of the transparent polyamideimide resin is preferably 90% or more, more preferably 93% or more, and further preferably 96% or more. From the viewpoint of storage stability of the composition, the imidization ratio is preferably not less than the above-described lower limit. The upper limit of the imidization rate is 100% or less. The imidization ratio represents a ratio of a molar amount of imide bonds in the transparent polyamideimide resin to a value 2 times as large as a molar amount of a structural unit derived from a tetracarboxylic acid compound in the transparent polyamideimide resin. When the transparent polyamideimide resin contains a tricarboxylic acid compound, it represents a ratio of a molar amount of an imide bond in the transparent polyamideimide resin with respect to a sum of a value 2 times as large as a molar amount of a structural unit derived from a tetracarboxylic acid compound in the transparent polyamideimide resin and a molar amount of a structural unit derived from a tricarboxylic acid compound. The imidization ratio can be determined by an IR method, an NMR method, or the like, and for example, in the NMR method, the method described in examples can be used for the measurement.

In a preferred embodiment of the present invention, the transparent polyamideimide resin may contain a halogen atom such as a fluorine atom which can be introduced, for example, through the above-mentioned fluorine-containing substituent and the like. When the transparent polyamideimide resin contains a halogen atom, the composition has storage stability and the yellowness (YI value) of the optical film obtained is easily decreased. When the yellowness of the optical film is low, the transparency of the optical film obtained is easily improved. The halogen atom is preferably a fluorine atom. Examples of the preferable fluorine-containing substituent for making the transparent polyamideimide resin contain a fluorine atom include a fluorine group and a trifluoromethyl group.

The content of the halogen atom in the transparent polyamideimide resin is preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and still more preferably 5 to 30% by mass, based on the mass of the transparent polyamideimide resin. When the content of the halogen atom is not less than the above lower limit, the storage stability of the composition is easily improved, and the yellowness of the optical film is easily reduced. When the content of the halogen atom is not more than the above upper limit, the synthesis is easy.

In the composition of the present invention, the content of the transparent polyamideimide resin is preferably 5% by mass or more, more preferably 7% by mass or more, further preferably 10% by mass or more, preferably 50% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, based on the mass of the composition. When the content of the transparent polyamideimide resin is within the above range, the storage stability of the composition is easily improved, and the viscosity suitable for film formation of the composition is easily obtained, so that the workability is improved.

< method for producing transparent polyamideimide resin >

The transparent polyamideimide resin can be produced, for example, from a tetracarboxylic acid compound, a dicarboxylic acid compound and a diamine compound as main raw materials. In one embodiment of the present invention, the transparent polyamideimide resin can be produced, for example, by a method comprising a step of reacting a diamine compound with a tetracarboxylic acid compound to produce a polyamic acid, a step of reacting the polyamic acid with a dicarboxylic acid compound to produce a polyamideimide precursor, and a step of imidizing the polyamideimide precursor. Here, the dicarboxylic acid compound preferably contains at least a compound represented by the formula (3 ").

[ formula (3) ], R¹～R⁸Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹～R⁸The hydrogen atoms contained in (a) may be substituted independently of each other by halogen atoms,

a represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-, -S-, -CO-or-NR⁹-，R⁹A hydrocarbon group having 1 to 12 carbon atoms which is a hydrogen atom or a hydrocarbon group which may be substituted with a halogen atom,

m represents an integer of 0 to 4,

R³¹and R³²Independently of one another, represents a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group or a chlorine atom]

In a preferred embodiment, the dicarboxylic acid compound is a compound represented by the formula (3') wherein A is an oxygen atom. In another preferred embodiment, the dicarboxylic acid compound is R³¹、 R³²A compound represented by the formula (3') which is a chlorine atom. In addition, a diisocyanate compound may be used instead of the diamine compound.

Examples of the diamine compound that can be used for producing the transparent polyamideimide resin include aliphatic diamines, aromatic diamines, and mixtures thereof. In this embodiment, the "aromatic diamine" refers to a diamine in which an amino group is directly bonded to an aromatic ring, and may include an aliphatic group or another substituent in a part of the structure. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring, but the aromatic ring is not limited thereto. Of these, benzene rings are preferred. The "aliphatic diamine" refers to a diamine in which an amino group is directly bonded to an aliphatic group, and may contain an aromatic ring or other substituent in a part of the structure.

Examples of the aliphatic diamine include acyclic aliphatic diamines such as 1, 6-hexamethylenediamine, and cyclic aliphatic diamines such as 1, 3-bis (aminomethyl) cyclohexane, 1, 4-bis (aminomethyl) cyclohexane, norbornanediamine, and 4, 4' -diaminodicyclohexylmethane. These can be used alone or in combination of 2 or more.

Examples of the aromatic diamine include aromatic diamines having 1 aromatic ring such as p-phenylenediamine, m-phenylenediamine, 2, 4-tolylenediamine, m-xylylenediamine, p-xylylenediamine, 1, 5-diaminonaphthalene and 2, 6-diaminonaphthalene, 4 ' -diaminodiphenylmethane, 4 ' -diaminodiphenylpropane, 4 ' -diaminodiphenyl ether, 3 ' -diaminodiphenyl ether, 4 ' -diaminodiphenyl sulfone, 3 ' -diaminodiphenyl sulfone, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, 1, 5-diaminonaphthalene, 2, 6-diaminonaphthalene, etc., 4 ' -, Bis [4- (3-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 2 ' -dimethylbenzidine, 2 ' -bis (trifluoromethyl) -4, 4 ' -diaminobiphenyl (sometimes referred to as TFMB), aromatic diamines having 2 or more aromatic rings, such as 4, 4' -bis (4-aminophenoxy) biphenyl, 9-bis (4-aminophenyl) fluorene, 9-bis (4-amino-3-methylphenyl) fluorene, 9-bis (4-amino-3-chlorophenyl) fluorene, and 9, 9-bis (4-amino-3-fluorophenyl) fluorene. These can be used alone or in combination of 2 or more.

Preferred examples of the aromatic diamine include 4, 4 '-diaminodiphenylmethane, 4' -diaminodiphenylpropane, 4 '-diaminodiphenyl ether, 3' -diaminodiphenyl ether, 4 '-diaminodiphenylsulfone, 3' -diaminodiphenylsulfone, 1, 4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 2 '-dimethylbenzidine, 2' -bis (trifluoromethyl) -4, 4 '-diaminobiphenyl (TFMB), 4' -bis (4-aminophenoxy) biphenyl, and more preferably 4, 4 '-diaminodiphenylmethane, 4' -diaminodiphenylpropane, 4 '-diaminodiphenyl ether, 4' -diaminodiphenylsulfone, 1, 4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2 '-dimethylbenzidine, 2' -bis (trifluoromethyl) -4, 4 '-diaminobiphenyl (TFMB), 4' -bis (4-aminophenoxy) biphenyl. These can be used alone or in combination of 2 or more.

Among the diamine compounds, 1 or more selected from the group consisting of aromatic diamines having a biphenyl structure are preferably used from the viewpoint of storage stability of the composition and high surface hardness, high transparency, high flexibility, high bending resistance and low coloring property of the optical film to be obtained. More preferably, 1 or more selected from the group consisting of 2, 2 '-dimethylbenzidine, 2' -bis (trifluoromethyl) benzidine, 4 '-bis (4-aminophenoxy) biphenyl, and 4, 4' -diaminodiphenyl ether is used, and still more preferably, 2 '-bis (trifluoromethyl) -4, 4' -diaminobiphenyl (TFMB) is used.

Examples of tetracarboxylic acid compounds that can be used for the production of transparent polyamideimide resins include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydrides; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compound may be used alone or in combination of 2 or more. The tetracarboxylic acid compound may be a dianhydride, or may be a tetracarboxylic acid compound analog such as an acid chloride compound.

Specific examples of the aromatic tetracarboxylic dianhydride include non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides, and condensed polycyclic aromatic tetracarboxylic dianhydrides. Examples of the non-condensed polycyclic aromatic tetracarboxylic acid dianhydride include 4, 4 ' -oxydiphthalic dianhydride, 3, 3 ', 4, 4 ' -benzophenonetetracarboxylic acid dianhydride, 2 ', 3, 3 ' -benzophenonetetracarboxylic acid dianhydride, 3, 3 ', 4, 4 ' -biphenyltetracarboxylic acid dianhydride, 2 ', 3, 3 ' -biphenyltetracarboxylic acid dianhydride, 3, 3 ', 4, 4 ' -diphenylsulfonetetracarboxylic acid dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 2-bis (3, 4-dicarboxyphenoxyphenyl) propane dianhydride, 4, 4 ' - (hexafluoroisopropylidene) diphthalic dianhydride (4, 4 ' - (hexafluoroisopropylidene) diphthallic dianhydride, sometimes described as 6FDA), 1, 2-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1, 2-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, 4 '- (p-phenylenedioxy) diphthalic dianhydride, 4' - (m-phenylenedioxy) diphthalic dianhydride. Examples of the monocyclic aromatic tetracarboxylic acid dianhydride include 1, 2, 4, 5-benzenetetracarboxylic acid dianhydride, and examples of the condensed polycyclic aromatic tetracarboxylic acid dianhydride include 2, 3, 6, 7-naphthalenetetracarboxylic acid dianhydride.

Among these, preferred examples include 4, 4 '-oxydiphthalic dianhydride, 3, 3', 4, 4 '-benzophenonetetracarboxylic dianhydride, 2', 3, 3 '-benzophenonetetracarboxylic dianhydride, 3, 3', 4, 4 '-biphenyltetracarboxylic dianhydride, 2', 3, 3 '-biphenyltetracarboxylic dianhydride, 3, 3', 4, 4 '-diphenylsulfonetetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 2-bis (3, 4-dicarboxyphenoxyphenyl) propane dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride (6FDA), 1, 2-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1, 2-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, 4, 4 '- (terephthaloxy) diphthalic dianhydride and 4, 4' - (isophthaloxy) diphthalic dianhydride, more preferably 4, 4 '-oxydiphthalic dianhydride, 3, 3', 4, 4 '-biphenyltetracarboxylic dianhydride, 2', 3, 3 '-biphenyltetracarboxylic dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride (6FDA), bis (3, 4-dicarboxyphenyl) methane dianhydride and 4, 4' - (p-phenylenedioxy) diphthalic dianhydride. These can be used alone or in combination of 2 or more.

Examples of the aliphatic tetracarboxylic dianhydride include cyclic and acyclic aliphatic tetracarboxylic dianhydrides. The cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include cycloalkanetetracarboxylic dianhydrides such as 1, 2, 4, 5-cyclohexanetetracarboxylic dianhydride, 1, 2, 3, 4-cyclobutanetetracarboxylic dianhydride and 1, 2, 3, 4-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3, 5, 6-tetracarboxylic dianhydride, dicyclohexyl-3, 3 ', 4, 4' -tetracarboxylic dianhydride and positional isomers thereof. These can be used alone or in combination of 2 or more. Specific examples of the acyclic aliphatic tetracarboxylic acid dianhydride include 1, 2, 3, 4-butanetetracarboxylic acid dianhydride, and 1, 2, 3, 4-pentanedicarboxylic acid dianhydride, and these can be used alone or in combination of 2 or more. In addition, cyclic aliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride may be used in combination.

Among the tetracarboxylic dianhydrides, from the viewpoint of the storage stability of the composition and the high surface hardness, high transparency, high flexibility, high bending resistance, and low coloring property of the optical film to be obtained, 4, 4 '-oxydiphthalic dianhydride, 3, 3', 4, 4 '-benzophenone tetracarboxylic dianhydride, 3, 3', 4, 4 '-biphenyl tetracarboxylic dianhydride, 2', 3, 3 '-biphenyl tetracarboxylic dianhydride, 3, 3', 4, 4 '-diphenylsulfone tetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof are preferable, and 3, 3 ', 4, 4' -biphenyl tetracarboxylic dianhydride and 4, 4 '- (hexafluoroisopropylidene) diphthalic dianhydride, 4' -biphenyl diphthalic dianhydride, and mixtures thereof are more preferable, And mixtures thereof, more preferably 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride (6 FDA).

As the dicarboxylic acid compound that can be used for the production of the transparent polyamideimide resin, terephthalic acid, 4' -oxybis-benzoic acid or an acid chloride compound thereof can be preferably used. In addition to terephthalic acid, 4' -oxybenzoic acid or their acid chloride compounds, other dicarboxylic acid compounds can also be used. Examples of the other dicarboxylic acid compound include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and their analogous acid chloride compounds and acid anhydrides, and 2 or more kinds thereof can be used in combination. Specific examples thereof include isophthalic acid; naphthalenedicarboxylic acid; 4, 4' -biphenyldicarboxylic acid; 3, 3' -biphenyldicarboxylic acid; dicarboxylic acid compound of chain hydrocarbon having carbon number of 8 or less and 2 benzoic acids via single bond, -CH₂-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or phenylene group-linked compounds and their acid chloride compounds. Specifically, 4 '-oxybis (benzoyl chloride) and terephthaloyl chloride are preferable, and a combination of 4, 4' -oxybis (benzoyl chloride) and terephthaloyl chloride is more preferable.

The transparent polyamideimide resin may be a product obtained by further reacting tetracarboxylic acid, tricarboxylic acid, and their anhydrides and derivatives, in addition to the tetracarboxylic acid compound, within a range that does not impair various physical properties of the composition and the optical film to be obtained.

Examples of the tetracarboxylic acid include water adducts of anhydrides of the above tetracarboxylic acid compounds.

Examples of the tricarboxylic acid compound include an aromatic tricarboxylic acid, an aliphatic tricarboxylic acid, and a chloride compound and an acid anhydride similar thereto, and 2 or more kinds thereof may be used in combination. Specific examples thereof include anhydrides of 1, 2, 4-benzenetricarboxylic acid; 2, 3, 6-naphthalene tricarboxylic acid-2, 3-anhydride; phthalic anhydride and benzoic acid via single bond, -O-, -CH₂-、-C(CH₃)₂-、-C(CF₃)₂-、 -SO₂-or phenylene groups.

In the production of the transparent polyamideimide resin, the amount of the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound to be used may be appropriately selected depending on the ratio of each structural unit of the desired transparent polyamideimide resin.

In the production of the transparent polyamideimide resin, the reaction temperature of the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound is not particularly limited, and is, for example, 20 to 200 ℃, preferably 25 to 100 ℃. The reaction time is also not particularly limited, and is, for example, about 30 minutes to 10 hours. If necessary, the reaction may be carried out in an inert atmosphere or under reduced pressure. In a preferred embodiment, the reaction is carried out under normal pressure and/or in an inert gas atmosphere while stirring. The reaction is preferably carried out in a solvent inert to the reaction. The solvent is not particularly limited as long as it does not affect the reaction, and examples thereof include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ -butyrolactone, γ -valerolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; alicyclic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as N, N-dimethylacetamide and N, N-dimethylformamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; carbonate-based solvents such as ethylene carbonate and 1, 2-propylene carbonate; and combinations thereof (mixed solvents). Among these, an amide solvent is preferably used from the viewpoint of solubility.

In the imidization step in the production of the transparent polyamideimide resin, imidization may be performed in the presence of an imidization catalyst. Examples of the imidization catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; n-ethylpiperazinePyridine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepino

Alicyclic amines (monocyclic); azabicyclo [2.2.1]Heptane, azabicyclo [3.2.1]Octane, azabicyclo [2.2.2]Octane, and azabicyclo [3.2.2]Alicyclic amines (polycyclic) such as nonane; and aromatic amines such as pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline), 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2, 4-dimethylpyridine, 2, 4, 6-trimethylpyridine, 3, 4-cyclopentenopyridine, 5, 6, 7, 8-tetrahydroisoquinoline, and isoquinoline. In addition, from the viewpoint of facilitating the imidization reaction, it is preferable to use an imidization catalyst together with an acid anhydride. Examples of the acid anhydride include conventional acid anhydrides usable in the imidization reaction, and specific examples thereof include aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic acid anhydrides such as phthalic anhydride.

The transparent polyamideimide resin obtained by imidization can be isolated (separation and purification) by a conventional method, for example, separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a combination thereof, and in a preferred embodiment, the transparent polyamideimide resin can be isolated by precipitating the transparent polyamideimide resin by adding a large amount of an alcohol such as methanol to a reaction solution containing the transparent polyamideimide resin, and then concentrating, filtering, drying, or the like.

< additives >

The compositions of the present invention may comprise a filler. Examples of the filler include organic particles and inorganic particles, and preferably inorganic particles. Examples of the inorganic particles include silica, zirconia, alumina, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, Indium Tin Oxide (ITO), metal oxide particles such as antimony oxide and cerium oxide, and metal fluoride particles such as magnesium fluoride and sodium fluoride, and among these, silica particles, zirconia particles and alumina particles are preferable from the viewpoint of easily improving the impact resistance of the optical film to be obtained, and silica particles are more preferable. These fillers may be used alone or in combination of 2 or more.

The average primary particle diameter of the filler (preferably, silica particles) is preferably 10nm or more, more preferably 15nm or more, further preferably 20nm or more, preferably 100nm or less, more preferably 90nm or less, further preferably 80nm or less, further preferably 70nm or less, particularly preferably 60nm or less, particularly preferably 50nm or less, and particularly preferably 40nm or less. When the average primary particle diameter of the silica particles is in the above range, aggregation of the silica particles is easily suppressed, and the optical properties of the obtained optical film are improved. The average primary particle diameter of the filler can be measured by the BET method. The primary particle size (average primary particle size) can be measured by image analysis using a Transmission Electron Microscope (TEM) or a Scanning Electron Microscope (SEM).

When the composition of the present invention contains a filler, preferably silica particles, the content of the filler, preferably silica particles is usually 0.1 part by mass or more, preferably 1 part by mass or more, more preferably 5 parts by mass or more, further preferably 10 parts by mass or more, particularly preferably 20 parts by mass or more, particularly preferably 30 parts by mass or more, and preferably 60 parts by mass or less, per 100 parts by mass of the composition. When the content of the filler is not less than the above lower limit, the elastic modulus of the optical film to be obtained is easily increased. When the content of the filler is not more than the above upper limit, the storage stability of the composition can be improved, precipitation or gelation of the resin and the like can be easily suppressed, and the optical properties of the optical film to be obtained can be easily improved.

The composition of the present invention may further comprise an ultraviolet absorber. The ultraviolet absorber can be appropriately selected from those generally used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light having a wavelength of 400nm or less. Examples of the ultraviolet absorber include at least 1 compound selected from the group consisting of benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds, and triazine-based compounds. The ultraviolet absorber may be used alone or in combination of two or more. Since the composition contains the ultraviolet absorber, deterioration of the resin can be suppressed, and thus, visibility can be improved when the obtained optical film is applied to an image display device or the like. In the present specification, the term "related compound" refers to a derivative of a compound to which the "related compound" is attached. For example, the "benzophenone-based compound" refers to a compound having benzophenone as a matrix skeleton and a substituent bonded to benzophenone.

When the composition contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 3 parts by mass or more, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 6 parts by mass or less, per 100 parts by mass of the composition. The preferable content varies depending on the ultraviolet absorber used, and when the content of the ultraviolet absorber is adjusted so that the light transmittance at 400nm becomes about 20 to 60%, the light resistance of the optical film obtained can be improved and an optical film having high transparency can be obtained.

The composition of the present invention may further contain other additives besides the filler and the ultraviolet absorber. Examples of the other additives include an antioxidant, a release agent, a stabilizer, a bluing agent, a flame retardant, a pH adjuster, a silica dispersant, a lubricant, a thickener, and a leveling agent. When other additives are contained, the content thereof may be preferably 0.005 to 20 parts by mass, more preferably 0.01 to 15 parts by mass, and still more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the composition.

The composition of the present invention can have a viscosity suitable for film formation because it contains the solvent (X). The viscosity at 25 ℃ of the composition of the present invention measured in accordance with JIS K5600-2-3 is preferably 5,000 mPas or more, more preferably more than 10,000 mPas, still more preferably 15,000 mPas or more, particularly preferably 20,000 mPas or more, preferably 110,000 mPas or less, more preferably 100,000 mPas or less. When the viscosity of the composition is within the above range, the storage stability of the composition is easily improved. When the viscosity of the composition is not more than the above upper limit, the workability at the time of film formation is easily improved.

The composition of the present invention can be obtained by mixing the transparent polyamideimide resin, the solvent (X), and, if necessary, the filler, the ultraviolet absorber, the other additives, and the like. For example, the transparent polyamideimide resin may be dissolved in the solvent (X), and the filler, the ultraviolet absorber, the other additives, and the like may be added and mixed with stirring as necessary to prepare a composition.

[ optical film ]

The present invention includes optical films formed from the compositions of the present invention. The optical film of the present invention is formed from a composition that effectively suppresses or prevents precipitation or gelation of a transparent polyamideimide resin or the like, and therefore can have excellent optical characteristics such as high total light transmittance, low yellowness (YI value), and low haze. In particular, the optical film of the present invention can exhibit excellent optical characteristics even when formed after being stored for a long period of time. In the present specification, the term "optical properties" means, for example, properties that can be evaluated optically, including total light transmittance, yellowness, and haze, and the term "improvement of optical properties" means improvement of total light transmittance, reduction of yellowness, reduction of haze, and the like.

The thickness of the optical film of the present invention can be suitably adjusted depending on the application, and is preferably 25 μm or more, more preferably 27 μm or more, further preferably 30 μm or more, preferably 100 μm or less, more preferably 80 μm or less, further preferably 65 μm or less, and particularly preferably 55 μm or less. The thickness of the optical film can be measured by a film thickness meter or the like, for example, by the method described in examples.

In the optical film of the present invention, the total light transmittance at a thickness of 50 μm is preferably 80% or more, more preferably 85% or more, further preferably 90% or more, and particularly preferably 91% or more. When the total light transmittance is not less than the above-described lower limit, the transparency becomes good, and for example, in the case of being used for a front panel of an image display device, high visibility can be contributed. The upper limit of the total light transmittance is usually 100% or less. The total light transmittance can be measured, for example, according to JIS K7361-1: 1997. the haze can be measured by using a haze computer, for example, by the method described in examples.

The haze of the optical film of the present invention is preferably 3.0% or less, more preferably 2.0% or less, still more preferably 1.0% or less, still more preferably 0.5% or less, and particularly preferably 0.3% or less. When the haze of the optical film is not more than the above upper limit, the transparency becomes good, and for example, when the optical film is applied to a front panel of an image display device, the optical film can contribute to high visibility. The lower limit of the haze is usually 0.01% or more. The haze can be measured according to JIS K7136: 2000. the haze can be measured by using a haze computer, for example, by the method described in examples.

The yellowness (YI value) of the optical film of the present invention is preferably 8 or less, more preferably 5 or less, further preferably 3 or less, and particularly preferably 2 or less. When the yellowness index of the optical film is not more than the above upper limit, the transparency becomes good, and for example, when the optical film is applied to a front panel of an image display device, the optical film can contribute to high visibility. The yellowness index is usually-5 or more, preferably-2 or more. The yellowness index (YI value) can be calculated by measuring the transmittance to light of 300 to 800nm using an ultraviolet-visible near-infrared spectrophotometer to obtain the tristimulus value (X, Y, Z) and calculating the tri-stimulus value based on the formula YI of 100 × (1.2769X-1.0592Z)/Y. For example, the measurement can be carried out by the method described in examples.

The optical film of the present invention can exhibit excellent optical characteristics even after the composition is stored for a long period of time, and therefore the total light transmittance, the haze and the yellowness index may be those of an optical film formed from the composition after storage.

In one embodiment of the present invention, the optical film of the present invention comprises the composition. With this optical film, since a large amount of the solvent is removed by drying during the manufacturing process, the solvent content is reduced compared to the composition. The content of the solvent contained in the optical film of the present invention is preferably 0.01 part by mass or more, more preferably 0.02 part by mass or more, further preferably 0.05 part by mass or more, particularly preferably 0.1 part by mass or more, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, further preferably 1 part by mass or less, and particularly preferably 0.9 part by mass or less, relative to 100 parts by mass of the optical film. When the content of the solvent contained in the optical film is not less than the above lower limit, the yellowness index of the optical film is easily reduced, and when the content of the solvent is not more than the above upper limit, the surface hardness of the optical film is easily increased.

[ method for producing optical film ]

The optical film of the present invention is not particularly limited, and can be produced, for example, by a method including the following steps:

(a) a step (coating step) of applying the composition (resin varnish) to a support material to form a coating film, and

(b) and a step (film forming step) of drying the applied liquid (coating film) to form an optical film.

In the coating step, a resin varnish is applied to the support material by a known coating method to form a coating film. Examples of known coating methods include roll coating methods such as wire bar coating, reverse coating, and gravure coating, die coating, comma coating, lip coating, spin coating, screen coating, spray coating, dipping, spraying, and casting.

In the film forming step, the coating film is dried and peeled from the support material, whereby an optical film can be formed. A step of drying the optical film may be further provided after the peeling. The drying of the coating film can be usually carried out at a temperature of 50 to 350 ℃. If necessary, the coating film may be dried in an inert atmosphere or under reduced pressure.

Examples of the support material include a metal tape such as SUS, and resin films such as a PET film, a PEN film, another polyimide film, a polyamide film, and a polyamideimide film. Among them, from the viewpoint of excellent heat resistance, a PET film, a PEN film, and the like are preferable, and from the viewpoint of adhesion to an optical film at the time of film formation, easy peelability, and cost, a PET film is preferable.

[ optical layered body ]

The optical film of the present invention may be an optical laminate formed by laminating 1 or more functional layers on at least one surface. Examples of the functional layer include an ultraviolet absorbing layer, a hard coat layer, a primer layer, a gas barrier layer, a hue adjusting layer, and a refractive index adjusting layer. The functional layers may be used alone or in combination of two or more.

The ultraviolet absorbing layer is a layer having a function of absorbing ultraviolet rays, and may be composed of a main material selected from an ultraviolet curing type transparent resin, an electron beam curing type transparent resin, and a thermosetting type transparent resin, and an ultraviolet absorber dispersed in the main material. Examples of the ultraviolet absorber include the same ultraviolet absorbers as those usable in the present composition. As the transparent resin, various known resins can be used within a range not impairing the effects of the present invention.

For the aforementioned optical film, a hard coat layer may be provided on at least one side thereof. The thickness of the hard coat layer is not particularly limited, and may be, for example, 2 to 100 μm. When the thickness of the hard coat layer is in the above range, the scratch resistance can be secured, and the following tendency is present: the bending resistance is not easily lowered, and curling due to curing shrinkage is not easily generated.

The hard coat layer can be formed by curing a hard coat layer composition containing a reactive material that forms a crosslinked structure by irradiation with an active energy ray or thermal energy, and is preferably formed by curing with an active energy ray, and the active energy ray is defined as an energy ray that can decompose a compound that generates an active species to generate an active species, and examples of the active energy ray include visible light, ultraviolet light, infrared light, X-ray, α ray, β ray, gamma ray, and electron beam, and preferably ultraviolet ray.

The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of the radical polymerizable compound may be a functional group capable of undergoing a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond, and specifically include a vinyl group and a (meth) acryloyl group. When the radical polymerizable compound has 2 or more radical polymerizable groups, the radical polymerizable groups may be the same or different. The number of radical polymerizable groups in 1 molecule of the radical polymerizable compound is preferably 2 or more in terms of increasing the hardness of the hard coat layer. Among the above radical polymerizable compounds, compounds having a (meth) acryloyl group are preferable from the viewpoint of the high or low reactivity, and oligomers having a plurality of (meth) acryloyl groups in the molecule and having a molecular weight of several hundred to several thousand, which are called multifunctional acrylate monomers having 2 to 6 (meth) acryloyl groups in 1 molecule, called epoxy (meth) acrylates, urethane (meth) acrylates, and polyester (meth) acrylates, are more preferable, and 1 or more selected from epoxy (meth) acrylates, urethane (meth) acrylates, and polyester (meth) acrylates are further preferable.

The cationically polymerizable compound is a compound having a cationically polymerizable group such as an epoxy group, an oxetane group, or a vinyl ether group. The number of the cationically polymerizable groups contained in 1 molecule of the cationically polymerizable compound is preferably 2 or more, and more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer. Among the above cationically polymerizable compounds, a compound having at least 1 of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferable because shrinkage of a cyclic ether group such as an epoxy group and an oxetanyl group accompanying a polymerization reaction is small. Among the cyclic ether groups, compounds having various structures are easily obtained, and therefore, a hard coat layer obtained is not adversely affected in durability and is easily controlled in compatibility with a radical polymerizable compound.

Among the cyclic ether groups, an oxetanyl group is preferable to an epoxy group because it has the following advantages: the polymerization degree is easily increased, the toxicity is low, the network formation rate of the cationic polymerizable compound in the obtained hard coat layer is increased, and even in the region where the cationic polymerizable compound is mixed with the radical polymerizable compound, the unreacted monomer does not remain in the film, and an independent network is formed.

Examples of the cationically polymerizable compound having an epoxy group include alicyclic epoxy resins obtained by epoxidizing polyglycidyl ethers of alicyclic polyols or compounds containing cyclohexene rings or cyclopentene rings with an appropriate oxidizing agent such as hydrogen peroxide; aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers and copolymers of glycidyl (meth) acrylate; glycidyl ethers produced by the reaction of bisphenols such as bisphenol a, bisphenol F and hydrogenated bisphenol a, or derivatives thereof such as alkylene oxide adducts and caprolactone adducts with epichlorohydrin, and glycidyl ether type epoxy resins derived from bisphenols such as NOVOLAC epoxy resins.

The aforementioned hard coating composition may further comprise a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, and they can be appropriately selected and used. These polymerization initiators are decomposed by at least one of irradiation with active energy rays and heating to generate radicals or cations, and radical polymerization or cationic polymerization is carried out.

The radical polymerization initiator may release a substance that initiates radical polymerization by at least one of irradiation with active energy rays and heating. Examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.

The active energy ray radical polymerization initiator includes a Type1 radical polymerization initiator which generates radicals by decomposition of molecules and a Type2 radical polymerization initiator which generates radicals by dehydrogenation in the coexistence of a tertiary amine, and they may be used alone or in combination.

The cationic polymerization initiator may release a substance that initiates cationic polymerization by at least one of irradiation with active energy rays and heating.

Examples of the cationic polymerization initiator include aromatic iodonium salts, aromatic sulfonium salts, and cyclopentadienyl iron (II) complexes. They can initiate cationic polymerization by either or both of irradiation with active energy rays or heating, depending on the difference in structure.

The amount of the polymerization initiator used is preferably 0.1 to 10% by mass based on 100% by mass of the entire hard coat composition. When the content of the polymerization initiator is within the above range, the curing can be sufficiently performed, the mechanical properties and the adhesion to the substrate of the hard coat layer to be finally obtained are easily improved, and the hard coat layer to be obtained is less likely to cause poor adhesion, cracking and curling due to curing shrinkage.

The aforementioned hard coating composition may further comprise one or more selected from the group consisting of a solvent, an additive.

The solvent is a substance capable of dissolving or dispersing the polymerizable compound and the polymerization initiator, and any known solvent for a hard coat composition in the art can be used without limitation.

The aforementioned additives may further include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

The hard coat layer may also serve as the ultraviolet absorbing layer by containing an ultraviolet absorber.

The primer layer is formed on the surface of the optical film of the present invention, when the above-described ultraviolet absorbing layer, hard coat layer, and the like are laminated, for example, to provide flatness or the like, or to further improve adhesion between these layers, and examples thereof include the primer layer described in japanese patent application laid-open No. 2017-194687.

The gas barrier layer is used for suppressing permeation of gas, particularly moisture, from the viewing side into the interior when used in a flexible display device described later, and examples thereof include those described in japanese patent application laid-open No. 2018-83417.

The hue adjustment layer is a layer having a function of adjusting the hue, and is a layer capable of adjusting the optical laminate to a target hue. The hue adjustment layer is, for example, a layer containing a resin and a colorant. Examples of the colorant include inorganic pigments such as titanium oxide, zinc oxide, red iron oxide, titanium oxide-based calcined pigments, ultramarine blue, cobalt aluminate, and carbon black; organic pigments such as azo-based compounds, quinacridone-based compounds, anthraquinone-based compounds, perylene-based compounds, isoindolinone-based compounds, phthalocyanine-based compounds, quinophthalone-based compounds, threne-based compounds, and diketopyrrolopyrrole-based compounds; bulk pigments such as barium sulfate and calcium carbonate; and basic dyes, acid dyes, mordant dyes, and the like.

The refractive index adjustment layer is a layer having a function of adjusting the refractive index, and is, for example, a layer having a refractive index different from that of the optical film and capable of providing a predetermined refractive index to the optical laminate. The refractive index adjusting layer may be, for example, a resin layer containing an appropriately selected resin and, in some cases, a pigment, or may be a thin film of a metal. Examples of the pigment for adjusting the refractive index include silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide, and tantalum oxide. The average primary particle diameter of the pigment may be 0.1 μm or less. By setting the average primary particle diameter of the pigment to 0.1 μm or less, diffuse reflection of light transmitted through the refractive index adjustment layer can be prevented, and deterioration in transparency can be prevented. Examples of the metal usable for the refractive index adjustment layer include metal oxides and metal nitrides such as titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, and silicon nitride.

The optical stack may further include a protective film. The protective film may be laminated on one or both sides of the optical film. When one surface of the optical film has a functional layer, the protective film may be laminated on the surface of the optical film or the surface of the functional layer, or may be laminated on both the optical film and the functional layer. In the case where the optical film has functional layers on both sides, the protective film may be laminated on the surface of one functional layer side or may be laminated on the surfaces of two functional layers. The protective film is a film for temporarily protecting the surface of the optical film or the functional layer, and is not particularly limited as long as it is a peelable film capable of protecting the surface of the optical film or the functional layer. Examples of the protective film include polyester resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; the resin film is preferably selected from the group consisting of polyolefin resin films, polyethylene, polypropylene films and the like, acrylic resin films and the like. When the optical laminate includes 2 protective films, the protective films may be the same or different.

The thickness of the protective film is not particularly limited, but is usually 10 to 100. mu.m, preferably 10 to 80 μm, and more preferably 10 to 50 μm. When the optical laminate includes 2 protective films, the thicknesses of the protective films may be the same or different.

In one embodiment of the present invention, the optical laminate may be wound around a core in a roll shape, and this form is referred to as a laminate film roll. Examples of the material constituting the core include synthetic resins such as polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyester resin, epoxy resin, phenol resin, melamine resin, silicone resin, polyurethane resin, polycarbonate resin, and ABS resin; metals such as aluminum; fiber-reinforced plastics (FRP: a composite material having increased strength by incorporating fibers such as glass fibers into plastics), and the like. The winding core is cylindrical or columnar, and has a diameter of, for example, 80 to 170 mm. The diameter of the laminate film roll (diameter after winding) is not particularly limited, and is usually 200 to 800 mm. In one embodiment of the present invention, the laminate film roll may have the following form: in the optical film production process, the support material is not peeled off from the optical film, and the laminate having the support material, the optical film, and optionally the functional layer and the protective film is wound around a winding core in a roll form. In the case of a laminate film roll, the laminate is often temporarily stored in the form of a film roll due to other restrictions such as space in continuous production, and in the case of a laminate film roll, the laminate is tightly wound, and therefore, substances causing cloudiness from the support material are easily transferred to the optical film. However, when a support material having a predetermined water contact angle is used, substances causing cloudiness from the support material are not easily transferred to the optical film, and cloudiness is not easily generated in the optical film or the optical laminate even when the laminate film roll is wound up.

[ Flexible image display device ]

The present invention includes a flexible display device including the optical film or the optical laminate. The individual optical films or optical laminates of the present invention are preferably used as front panels, sometimes referred to as window films, in flexible image display devices. The flexible image display device is formed of a laminate for flexible image display device, which is disposed on the viewing side of an organic EL display panel and is configured to be bendable, and the organic EL display panel. The laminate for a flexible image display device may further include a circularly polarizing plate and a touch sensor, and the lamination order thereof is arbitrary, but it is preferable to laminate the window film, the circularly polarizing plate, the touch sensor, or the window film, the touch sensor, and the circularly polarizing plate in this order from the viewing side. When the circularly polarizing plate is present on the viewing side of the touch sensor, the pattern of the touch sensor is less likely to be observed, and the displayed image is favorably visually recognized. The members may be laminated using an adhesive, a bonding agent, or the like. Further, the light-shielding film may include a light-shielding pattern formed on at least one surface of any one of the window film, the circularly polarizing plate, and the touch sensor.

[ polarizing plate ]

As described above, the flexible display device of the present invention includes a polarizing plate, preferably a circular polarizing plate. The circularly polarizing plate is a functional layer having a function of transmitting only a right-handed or left-handed circularly polarized light component by laminating a λ/4 phase difference plate on a linearly polarizing plate. For example, can be used for: by converting external light into right-handed circularly polarized light, the external light reflected by the organic EL panel and turned into left-handed circularly polarized light is blocked, and only the light emitting component of the organic EL is transmitted, whereby the influence of reflected light is suppressed, and an image can be easily observed. In order to realize the circularly polarized light function, the absorption axis of the linear polarizer and the slow axis of the λ/4 phase difference plate need to be 45 ° in theory, but in practical use, 45 ± 10 °. The linear polarizing plate and the λ/4 phase difference plate do not have to be laminated adjacent to each other as long as the relationship between the absorption axis and the slow axis satisfies the aforementioned range. It is preferable to realize fully circularly polarized light in the full wavelength range, but this is not necessarily the case in practical use, and therefore, the circularly polarizing plate in the present invention also includes an elliptically polarizing plate. It is also preferable to further laminate a λ/4 retardation film on the viewing side of the linear polarizing plate to convert the emitted light into circularly polarized light, thereby improving visibility in a state where the polarized sunglasses are worn.

The linear polarizing plate is a functional layer having the following functions: light vibrating in the direction of the transmission axis is passed through, but polarized light of the vibration component perpendicular thereto is blocked. The linear polarizing plate may be a single linear polarizer or a structure including a linear polarizer and a protective film attached to at least one surface of the linear polarizer. The thickness of the linearly polarizing plate may be 200 μm or less, and preferably 0.5 to 100 μm. When the thickness of the linear polarizer is within the above range, the flexibility of the linear polarizer tends to be less likely to decrease.

The linear polarizer may be a film-type polarizer produced by dyeing and stretching a polyvinyl alcohol (hereinafter, abbreviated as PVA) film. A polarizing performance is exhibited by adsorbing a dichroic dye such as iodine to a PVA film that has been oriented by stretching, or by stretching the film while the film is adsorbed to PVA to orient the dichroic dye. The film-type polarizer may be produced by steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying. The stretching and dyeing steps may be performed on the PVA-based film alone or in a state of being laminated with another film such as polyethylene terephthalate. The thickness of the PVA film to be used is preferably 10 to 100 μm, and the stretching ratio is preferably 2 to 10 times.

In addition, another example of the polarizer is a liquid crystal coating type polarizer formed by coating a liquid crystal polarizing composition. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. The liquid crystalline compound is preferably one having a property of exhibiting a liquid crystal state, and particularly preferably one having a high-order alignment state such as smectic or the like, since it can exhibit high polarizing performance. The liquid crystalline compound preferably has a polymerizable functional group.

The dichroic dye compound may have a polymerizable functional group, and may have liquid crystal properties by itself.

Any of the compounds contained in the liquid crystal polarizing composition has a polymerizable functional group. The liquid crystal polarizing composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like.

The liquid crystal polarizing layer may be manufactured by applying a liquid crystal polarizing composition on an alignment film to form a liquid crystal polarizing layer. The liquid crystal polarizing layer may be formed thinner than the film type polarizer, and preferably has a thickness of 0.5 to 10 μm, more preferably 1 to 5 μm.

The alignment film can be produced by, for example, applying an alignment film-forming composition to a base material, and imparting alignment properties by rubbing, irradiation with polarized light, or the like. The alignment film-forming composition may contain an alignment agent, and may further contain a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. Examples of the orientation agent include polyvinyl alcohols, polyacrylates, polyamide acids, and polyimides. In the case of using an aligning agent that imparts alignment properties by irradiation with polarized light, it is preferable to use an aligning agent containing a cinnamate group. The weight average molecular weight of the polymer that can be used as the orientation agent is, for example, about 10,000 to 1,000,000. The thickness of the alignment film is preferably 5 to 10,000nm, and more preferably 10 to 500nm in view of sufficiently developing an alignment controlling force.

The liquid crystal polarizing layer may be laminated by being peeled off from a substrate and transferred, or the substrate may be directly laminated. The substrate preferably functions as a transparent substrate for a protective film, a retardation plate, and a window film.

As the protective film, the same materials and additives as those used for the transparent base material of the window film may be used, and a transparent polymer film may be used. The protective film may be a coating type protective film obtained by coating and curing a cationically curable composition such as an epoxy resin or a radically curable composition such as an acrylate. The protective film may contain a plasticizer, an ultraviolet absorber, an infrared absorber, a pigment, a colorant such as a dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like, as required. The thickness of the protective film is preferably 200 μm or less, and more preferably 1 to 100 μm. When the thickness of the protective film is within the above range, the flexibility of the film tends not to be easily lowered.

The λ/4 retardation plate is a film that imparts a retardation of λ/4 to a direction perpendicular to the traveling direction of incident light (in-plane direction of the film). The λ/4 retardation plate may be a stretched retardation plate produced by stretching a polymer film such as a cellulose film, an olefin film, or a polycarbonate film. The λ/4 retardation plate may contain a retardation regulator, a plasticizer, an ultraviolet absorber, an infrared absorber, a pigment, a colorant such as a dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like, as required.

The thickness of the stretched phase difference plate is preferably 200 μm or less, and more preferably 1 to 100 μm. When the thickness of the stretched retardation film is within the above range, the flexibility of the stretched retardation film tends to be less likely to decrease.

Another example of the λ/4 retardation plate is a liquid crystal coating type retardation plate formed by coating a liquid crystal composition.

The liquid crystal composition contains a liquid crystalline compound which exhibits a liquid crystal state such as a nematic state, a cholesteric state, or a smectic state. The liquid crystalline compound has a polymerizable functional group.

The aforementioned liquid crystal composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like.

The liquid crystal coating type retardation plate can be produced by coating a liquid crystal composition on a substrate and curing the coating to form a liquid crystal retardation layer, similarly to the liquid crystal polarizing layer. The liquid crystal coating type retardation plate may be formed to have a thickness thinner than that of the stretching type retardation plate. The thickness of the liquid crystal polarizing layer is preferably 0.5 to 10 μm, and more preferably 1 to 5 μm.

The liquid crystal-coated retardation plate may be laminated by being peeled from a substrate and transferred, or the substrate may be directly laminated. The substrate preferably functions as a transparent substrate for a protective film, a retardation plate, and a window film.

In general, the birefringence is large as the wavelength is shorter, and the birefringence is small as the wavelength is longer. In this case, since a retardation of λ/4 cannot be achieved over the entire visible light region, the in-plane retardation is designed to be preferably 100 to 180nm, more preferably 130 to 150nm so as to be λ/4 with respect to the vicinity of 560nm, which has high visibility. From the viewpoint of good visibility, it is preferable to use an inverse dispersion λ/4 phase difference plate made of a material having a wavelength dispersion characteristic of birefringence opposite to that of the conventional material. As such a material, for example, a stretched retardation plate described in japanese patent application laid-open No. 2007-232873 and the like can be used, and a liquid crystal coated retardation plate described in japanese patent application laid-open No. 2010-30979 and the like can be used as a liquid crystal coated retardation plate.

As another method, a technique is known in which a broadband λ/4 phase difference plate is obtained by combining a λ/2 phase difference plate (for example, japanese patent application laid-open No. h 10-90521). The λ/2 phase difference plate can be manufactured by the same material method as the λ/4 phase difference plate. The combination of the stretching type retardation plate and the liquid crystal coating type retardation plate is arbitrary, and the thickness can be made thin by using the liquid crystal coating type retardation plate.

In order to improve visibility in an oblique direction, a method of laminating a normal C plate on the above-described circularly polarizing plate is known (for example, japanese patent application laid-open No. 2014-224837). The positive C plate may be a liquid crystal coated retardation plate or a stretched retardation plate. The retardation in the thickness direction of the retardation plate is preferably from-200 to-20 nm, more preferably from-140 to-40 nm.

[ touch sensor ]

As described above, the flexible display device of the present invention includes the touch sensor. The touch sensor may be used as an input mechanism. The touch sensor includes various types such as a resistive film type, a surface acoustic wave type, an infrared ray type, an electromagnetic induction type, and a capacitance type, and preferably includes a capacitance type.

The capacitive touch sensor is divided into an active region and an inactive region located in an outer region of the active region. The active region is a region corresponding to a region (display portion) where a screen is displayed on the display panel, and is a region where a touch by a user is sensed, and the inactive region is a region corresponding to a region (non-display portion) where the screen is not displayed in the display device. The touch sensor may include: a substrate having flexible properties; a sensing pattern formed on the active region of the substrate; and each sensing line formed in the inactive region of the substrate and used for connecting the sensing pattern with an external driving circuit through a pad (pad) part. As the substrate having a flexible property, the same material as the transparent substrate of the window film can be used.

The sensing pattern may include a 1 st pattern formed along a 1 st direction and a 2 nd pattern formed along a 2 nd direction. The 1 st pattern and the 2 nd pattern are arranged in different directions from each other. The 1 st pattern and the 2 nd pattern are formed in the same layer, and in order to sense a touched position, the patterns must be electrically connected. The 1 st pattern is in a form in which the plurality of unit patterns are connected to each other via the contacts, and the 2 nd pattern is in a structure in which the plurality of unit patterns are separated from each other in an island form, and therefore, in order to electrically connect the 2 nd pattern, an additional bridge electrode is required. As the electrode for connecting the 2 nd pattern, a known transparent electrode can be applied. Examples of the material of the transparent electrode include Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), zinc oxide (ZnO), Indium Zinc Tin Oxide (IZTO), Cadmium Tin Oxide (CTO), Indium Gallium Zinc Oxide (IGZO), PEDOT (poly (3, 4-ethylenedioxythiophene), poly (3, 4-ethylenedioxythiophene)), Carbon Nanotube (CNT), graphene, and a wire, and ITO is preferably used. These can be used alone or in combination of 2 or more. The metal usable for the wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, chromium, and the like, and these metals may be used alone or in combination of 2 or more.

The bridge electrode may be formed on the insulating layer with an insulating layer interposed therebetween on the sensing pattern, the bridge electrode may be formed on the substrate, and the insulating layer and the sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, or may be formed of molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of 2 or more of these.

The 1 st pattern and the 2 nd pattern must be electrically insulated, and thus, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the tab of the 1 st pattern and the bridge electrode, or may be formed as a layer covering the entire sensing pattern. In the case of a layer covering the entire sensing pattern, the 2 nd pattern may be connected to the bridge electrode through a contact hole formed in the insulating layer.

In the touch sensor, as a means for appropriately compensating for a difference in transmittance between a pattern region where a sensing pattern is formed and a non-pattern region where no sensing pattern is formed (specifically, a difference in transmittance due to a difference in refractive index in these regions), an optical adjustment layer may be further included between the substrate and the electrode. The optical adjustment layer may contain an inorganic insulating substance or an organic insulating substance. The optical adjustment layer can be formed by applying a photocurable composition containing a photocurable organic binder and a solvent onto a substrate. The photocurable composition may further comprise inorganic particles. The refractive index of the optical adjustment layer can be increased by the inorganic particles.

The photocurable organic binder may contain a copolymer of monomers such as an acrylate monomer, a styrene monomer, and a carboxylic acid monomer, for example, within a range not to impair the effects of the present invention. The photocurable organic binder may be, for example, a copolymer containing mutually different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit.

Examples of the inorganic particles include zirconia particles, titania particles, and alumina particles.

The photocurable composition may further contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing assistant.

[ adhesive layer ]

The layers (window film, circularly polarizing plate, touch sensor) forming the laminate for a flexible image display device and the film members (linearly polarizing plate, λ/4 phase difference plate, etc.) constituting the layers may be bonded together with an adhesive. As the adhesive, a commonly used adhesive such as an aqueous adhesive, an organic solvent adhesive, a solventless adhesive, a solid adhesive, an aqueous solvent volatile adhesive, a moisture curable adhesive, a heat curable adhesive, an anaerobic curable adhesive, an active energy ray curable adhesive, a curing agent hybrid adhesive, a hot melt adhesive, a pressure sensitive adhesive (adhesive), a remoistenable adhesive, or the like can be used, and an aqueous solvent volatile adhesive, an active energy ray curable adhesive, or an adhesive can be preferably used. The thickness of the adhesive layer can be adjusted as appropriate in accordance with the required adhesive strength, etc., and is preferably 0.01 to 500 μm, more preferably 0.1 to 300 μm. In the laminate for a flexible image display device, a plurality of adhesive layers are present, and the thickness and the type of each adhesive layer may be the same or different.

As the aqueous solvent volatile adhesive, a polyvinyl alcohol polymer, a water-soluble polymer such as starch, or a water-dispersed polymer such as an ethylene-vinyl acetate emulsion or a styrene-butadiene emulsion can be used as a main polymer. In addition to the main agent polymer and water, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be added. In the case of bonding with the aqueous solvent volatile adhesive, adhesiveness can be provided by injecting the aqueous solvent volatile adhesive between the layers to be bonded to bond the layers to be bonded together and then drying the layers. When the aqueous solvent volatile adhesive is used, the thickness of the adhesive layer is preferably 0.01 to 10 μm, more preferably 0.1 to 1 μm. When the aqueous solvent-volatile adhesive is used in a plurality of layers, the thickness and type of each layer may be the same or different.

The active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition containing a reactive material that forms an adhesive layer by irradiation with an active energy ray. The active energy ray-curable composition may contain at least 1 polymer of the same radical polymerizable compound and cationic polymerizable compound as those contained in the hard coat composition. As the radical polymerizable compound, the same compounds as those in the hard coat composition can be used.

As the cationic polymerizable compound, the same compound as the cationic polymerizable compound in the hard coat composition can be used. As the cationically polymerizable compound usable in the active energy ray-curable composition, an epoxy compound is particularly preferable. In order to reduce the viscosity as an adhesive composition, it is also preferable to include a monofunctional compound as a reactive diluent.

In order to reduce the viscosity, the active energy ray composition may contain a monofunctional compound. Examples of the monofunctional compound include an acrylate monomer having 1 (meth) acryloyl group in 1 molecule, a compound having 1 epoxy group or oxetanyl group in 1 molecule, and glycidyl (meth) acrylate.

The active energy ray composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, and they can be appropriately selected and used. These polymerization initiators are the following: the polymer can be decomposed by at least one of irradiation with active energy rays and heating to generate radicals or cations, and radical polymerization and cationic polymerization are carried out. The initiator described in the description of the hard coat composition, which can initiate at least either radical polymerization or cationic polymerization by irradiation with active energy rays, may be used.

The active energy ray-curable composition may further contain an ion scavenger, an antioxidant, a chain transfer agent, an adhesion-imparting agent, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, an antifoaming agent, an additive, and a solvent. When 2 adhesive layers are bonded by the active energy ray-curable adhesive, the active energy ray-curable composition may be applied to one or both of the adhesive layers and then bonded, and either or both of the adhesive layers may be irradiated with active energy rays and cured to bond them. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm. When the active energy ray-curable adhesive is used for forming a multilayer adhesive layer, the thickness and type of each layer may be the same or different.

As the adhesive, any adhesive classified into an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, and the like according to the base polymer can be used. The binder may contain a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, an adhesion-imparting agent, a plasticizer, a dye, a pigment, an inorganic filler, and the like in addition to the main polymer. The pressure-sensitive adhesive layer (adhesive layer) can be formed by dissolving and dispersing the components constituting the pressure-sensitive adhesive in a solvent to obtain a pressure-sensitive adhesive composition, applying the pressure-sensitive adhesive composition to a substrate, and drying the applied pressure-sensitive adhesive composition. The adhesive layer may be formed directly or by transferring an adhesive layer formed separately on the substrate. A release film is also preferably used to cover the pressure-sensitive adhesive surface before bonding. When the active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.1 to 500 μm, more preferably 1 to 300 μm. When a plurality of the above-mentioned adhesives are used, the thickness and kind of each layer may be the same or different.

[ light-shielding pattern ]

The light shielding pattern may be applied as at least a part of a bezel (bezel) or a housing of the flexible image display device. The wiring disposed at the edge of the flexible image display device is hidden by the light-shielding pattern and is not easily viewed, thereby improving visibility of an image. The light-shielding pattern may be in the form of a single layer or a plurality of layers. The color of the light-shielding pattern is not particularly limited, and may be various colors such as black, white, and metallic colors. The light-shielding pattern may be formed of a pigment for color, and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, or polysiloxane. They may be used alone or in the form of a mixture of 2 or more. The light-shielding pattern can be formed by various methods such as printing, photolithography, and inkjet. The thickness of the light-shielding pattern is preferably 1 to 100 μm, and more preferably 2 to 50 μm. Further, it is preferable to provide a shape such as an inclination in the thickness direction of the light-shielding pattern.

Examples

The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" in the examples mean mass% and parts by mass. First, the measurement and evaluation method will be explained.

< Haze (Haze) >

According to JIS K7136: the optical films obtained in examples and comparative examples were cut into a size of 30mm × 30mm, and the haze (%) was measured using a haze computer (Suga Test Instruments co., ltd., "HGM-2 DP").

< yellowness (YI value) >

The yellowness (Yellow Index): YI value) of the optical films obtained in examples and comparative examples was measured using an ultraviolet-visible near-infrared spectrophotometer "V-670" manufactured by Nippon spectral Co., Ltd. After background measurement was performed in a state where no sample was present, an optical film was placed on a sample holder, transmittance with respect to light of 300 to 800nm was measured to obtain a tristimulus value (X, Y, Z), and a YI value was calculated based on the following formula.

YI＝100×(1.2769X-1.0592Z)/Y

< Total light transmittance (Tt) >

According to JIS K7361-1: 1997, the optical films obtained in examples and comparative examples were cut into a size of 30mm × 30mm, and the total light transmittance (%) at a thickness of 50 μm of the optical film was measured using a haze computer ("HGM-2 DP").

< judgment of gel State >

1g of the transparent polyamideimide resin obtained in examples and comparative examples and 9g of the solvent were weighed, placed in a glass screw tube having a diameter of 27mm, and dissolved by heating on a hot plate at 70 ℃ while stirring and mixing. The resulting composition was slowly cooled to 25 ℃ and then left standing in an upright state for 1 hour. Then, the glass screw tube was laid down horizontally, and was further left standing for 1 hour. After 1 hour, the liquid surface was judged to be in a horizontal state as a solution state, and the liquid surface was judged not to be in a horizontal state as a gel state.

< measurement of viscosity >

The viscosities of the compositions obtained in examples and comparative examples were measured in accordance with JIS K5600-2-3. Specifically, 0.5mL of the composition was measured for viscosity (mPas) at 3.0rpm at 25 ℃ using an E-type viscometer (laminar viscometer DV-II + pro manufactured by BROOKFIELD) and spindle (spindle) S52.

< evaluation of storage stability of composition >

The compositions obtained in examples and comparative examples were weighed out in an amount of 1g, placed on a petri dish and left to stand at 25 ℃ and 60% RH for 14 hours, and after 14 hours, the varnish was transparent and judged to have good storage stability (○), and the polymer was confirmed to have precipitated and judged to be poor (x).

< weight average molecular weight (Mw) >)

Gel Permeation Chromatography (GPC) measurement

Pretreatment method

To the transparent polyamideimide resin obtained in the example, a DMF eluent (10mmol/L lithium bromide solution) was added so that the concentration became 2mg/mL, and the mixture was heated and cooled while stirring at 80 ℃ for 30 minutes, and then filtered through a 0.45 μm membrane filter, and the obtained filtrate was used as a measurement solution.

Measurement conditions

Column: TSKgel SuperAWM-H.times.2 + SuperAW 2500X 1(6.0mm I.D.. times.150 mm. times.3)

Eluent: DMF (with addition of 10mmol/L lithium bromide)

Flow rate: 1.0 mL/min

A detector: RI detector

Column temperature: 40 deg.C

Sample introduction amount: 100 μ L

Molecular weight standard: standard polystyrene

< thickness of optical film >

The thickness of the optical films obtained in examples and comparative examples was measured using a micrometer manufactured by Mitutoyo Corporation.

< imidization Rate >

The imidization ratios of the polyamideimide resins used in examples and comparative examples were determined by¹H-NMR was measured, and calculated using a signal derived from a partial structure represented by the following formula (Y). The method of calculating the imidization ratio from the measurement conditions and the obtained results is as follows.

(method of preparing measurement sample)

Dissolving polyamide-imide resin in deuterated dimethyl sulfoxide (DMSO-d)₆) In (3), a 2 mass% solution was prepared, and the obtained solution was used as a measurement sample.

(¹Measurement conditions of H-NMR

A measuring device: b is600MHz manufactured by ruker¹H-NMR apparatus AVANCE600

Temperature of the sample: 303K

The determination method comprises the following steps:¹H-NMR，HSQC

(method of calculating imidization ratio of polyamideimide resin)

The measurement sample was a solution containing a polyimide resin produced using a monomer from which a polyimide site was derived, among the polyamide-imide resins of examples and comparative examples¹In the H-NMR spectrum, the integral value of the signal from the proton (A) in the above formula (Y) is represented as Int_AThe integral value of the signal from the proton (B) is denoted as Int_B. From these values, the imidization ratio (%) was determined by the following formula (NMR-1).

[ mathematical formula 1]

Imidization rate (%) < 100 × (1-Int)_B/Int_A) (NMR-1)

In the HSQC spectrum obtained using the solution containing the polyimide resin as a measurement sample, the integral value of the signal from the proton (C) in the above formula (Y) is defined as Int_CThe average value of the integral values of the signals from the proton (D) and the proton (E) is Int_DEFrom these values, β values were obtained by the following formula (NMR-2).

[ mathematical formula 2]

β＝Int_DE/Int_c(NMR-2)

Next, β values based on the formula (NMR-2) and the imidization ratio (%) based on the formula (NMR-1) were obtained for a plurality of polyimide resins, and from the results, the following correlation formula (NMR-3) was obtained.

[ mathematical formula 3]

Imidization ratio (%) -115.9X β +100 (NMR-3)

Then, in the HSQC spectrum obtained by using the solution containing the polyamideimide resin as a measurement sample, β values were obtained by the formula (NMR-2) in the same manner as described above, and the imidization ratio (%) of the polyamideimide resin was obtained by substituting the β value into the above correlation formula (NMR-3).

[ example 1]

(preparation of transparent polyamideimide resin)

To a 1L separable flask equipped with a stirring blade, 45.00g (140.52mmol) of 2, 2 '-bis (trifluoromethyl) -4, 4' -diaminobiphenyl (TFMB) and 768.55g of N, N-dimethylacetamide (DMAc) were added under a nitrogen atmosphere, and TFMB was dissolved in DMAc with stirring at room temperature. Subsequently, 18.92g (42.58mmol) of 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added to the flask, and the mixture was stirred at room temperature for 3 hours. Then, 4.19g (14.19mmol) of 4, 4' -oxybis (benzoyl chloride) (OBBC) was added to the flask, and 17.29g (85.16mmol) of terephthaloyl chloride (TPC) was added thereto, followed by stirring at room temperature for 1 hour. Subsequently, 4.63g (49.68mmol) of 4-methylpyridine and 15.22g (149.04mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes, then heated to 70 ℃ using an oil bath, and further stirred for 3 hours to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, put into a large amount of methanol in a linear form, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Then, the precipitate was dried under reduced pressure at 100 ℃ to obtain a transparent polyamideimide resin. The weight average molecular weight of the obtained transparent polyamideimide resin was 320,000. The imidization ratio of the transparent polyamideimide resin was 97%.

(preparation of composition)

10g of the transparent polyamideimide resin obtained in the above-mentioned manner and 90g of N, N-Dimethylpropionamide (DMPA) were weighed and dissolved by stirring to prepare a composition (polyamideimide resin varnish).

(production of optical film)

The prepared composition was filtered with a filter having a mesh size of 10 μm, and then coated on a smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name "A4100") with an applicator so that the thickness of the self-supporting film became 55 μm, dried at 50 ℃ for 30 minutes, and then dried at 140 ℃ for 15 minutes, and the polyester substrate was peeled off to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and dried at 200 ℃ for 1 hour to obtain an optical film having a thickness of 50 μm.

[ example 2]

A composition and an optical film were obtained in the same manner as in example 1, except that 3-methoxy-N, N-dimethylpropionamide (MMPA) was used as a solvent in the preparation of the composition.

Comparative example 1

A composition and an optical film were obtained in the same manner as in example 1, except that N, N-dimethylacetamide (DMAc) was used as a solvent in the preparation of the composition.

[ example 3]

A composition and an optical film were obtained in the same manner as in example 1, except that a mixed solvent of γ -butyrolactone (GBL) and DMPA in a ratio of 1: 1 was used as the solvent in the preparation of the composition.

The compositions and optical films obtained in examples 1 to 3 and comparative example 1 were each shown in table 1 with respect to the solvent, the judgment result of the gel state, the judgment of the viscosity and the storage stability, and the total light transmittance, the yellowness index and the haze in the film state.

[ Table 1]

	Example 1	Example 2	Example 3	Comparative example 1
					Kind of solvent	DMPA	MMPA	GBL/DMPA＝1/1	DMAc
Judgment of gel State	Solutions of	Solutions of	Solutions of	Solutions of
					Viscosity (mPa. s)	22,000	96,000	85,000	22,000
Storage stability	○	○	○	×
					Total light transmittance (%)	91.7	91.3	91.3	91.4
Degree of yellowness	1.4	1.6	1.5	1.5
					Haze degree	0.2	0.2	0.2	0.2

As shown in Table 1, the compositions obtained in examples 1 to 3 were excellent in storage stability. In addition, the viscosity is suitable for film formation. The optical films obtained in examples 1 to 3 had high total light transmittance, low yellowness and haze, and excellent optical properties.

Claims

1. A composition comprising a transparent polyamideimide resin having at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a dicarboxylic acid compound, and a solvent represented by the formula (X),

in the formula (X), R^a1And R^a2Independently represent an alkyl group having 1 to 6 carbon atoms, R^a3Represents an alkyl group having 2 to 6 carbon atoms or an alkoxyalkyl group having 2 to 12 carbon atoms.

2. The composition according to claim 1, wherein the transparent polyamideimide resin has a weight average molecular weight of 150,000 or more in terms of polystyrene.

3. The composition according to claim 1 or 2, wherein the transparent polyamideimide resin has an imidization ratio of 90% or more.

4. The composition according to any one of claims 1 to 3, wherein the content of the transparent polyamideimide resin is 5% by mass or more relative to the mass of the composition.

5. The composition according to any one of claims 1 to 4, which has a viscosity of 5,000 to 100,000 mPas at 25 ℃ as measured in accordance with JIS K5600-2-3.

6. An optical film formed from the composition of any one of claims 1 to 5.

7. A flexible display device comprising the optical film according to claim 6.

8. The flexible display device of claim 7, further provided with a touch sensor.

9. The flexible display device according to claim 7 or 8, further comprising a polarizing plate.