KR20200044751A - Polyamideimide resin and optical film - Google Patents

Abstract

Provided is a polyamideimide resin capable of forming an optical film having excellent light resistance. The polyamideimide resin comprises a structural unit represented by formula (1) and formula (2), wherein, in the formula (1) and the formula (2), X each independently represents a divalent organic group, Y represents a tetravalent organic group, and Z represents a divalent heterocyclic ring.

Description

Polyamideimide resin and optical film {POLYAMIDEIMIDE RESIN AND OPTICAL FILM}

The present invention relates to a polyamideimide resin and an optical film capable of forming an optical film used as a front plate material for an image display device, and a flexible display device provided with the optical film.

Background Art Image display devices such as liquid crystal display devices and organic EL display devices are widely used in various applications such as mobile phones and smart watches. Glass has been used as the front plate of such an image display device, but since the glass is very rigid and fragile, it is difficult to use it as a front plate material such as, for example, a flexible display. As one of the materials to replace glass, an optical film formed of a polyamideimide resin has been studied (for example, Patent Document 1).

Japanese Patent Publication No. 2015-521687

The optical film is required to have light resistance to prevent discoloration even when exposed to ultraviolet light. However, according to the examination of the present inventors, it has been found that when the conventional optical film is exposed to ultraviolet light, light resistance may not be sufficient, for example, when the index indicating discoloration such as yellowness (YI) changes significantly. .

Accordingly, an object of the present invention is to provide a polyamideimide resin and an optical film capable of forming an optical film having excellent light resistance, and a flexible display device comprising the optical film.

As a result of diligent investigation to solve the above problems, the present inventors include structural units derived from dicarboxylic acid compounds having a divalent heterocycle as structural units derived from dicarboxylic acid compounds constituting the polyamideimide resin. Then, it has been found that the above problems can be solved, and the present invention has been completed. That is, the following preferable aspect is contained in this invention.

[1] Expression (1) and Expression (2)

[In formula (1) and formula (2), X each independently represents a divalent organic group, Y represents a tetravalent organic group, and Z represents a divalent heterocyclic ring]

The polyamideimide resin containing the structural unit represented by.

[2] The polyamideimide resin according to [1], wherein Z is a divalent heterocyclic ring containing a sulfur atom.

[3] In the formula (2), Z is the formula (a)

[In the formula (a), R ^a and R ^b each independently 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, and R ^a and R ^b are They may be bonded to each other, and hydrogen atoms contained in R ^a and R ^b may be each independently substituted with a halogen atom, and * represents a bonding hand]

The polyamideimide resin according to [1] or [2], which is a divalent heterocyclic ring represented by.

[4] The polyamideimide resin according to any one of [1] to [3], wherein the content of the structural unit represented by formula (2) is 0.1 to 10 moles per 1 mole of the structural unit represented by formula (1).

[5] An optical film comprising the polyamideimide resin according to any one of [1] to [4].

[6] Equations (1) and (2b)

[In formula (1) and formula (2b), X and L each independently represent a divalent organic group, and Y represents a tetravalent organic group]

The polyamide-imide resin containing the structural unit represented by,

The optical film whose light transmittance at wavelength 420 nm is 70% or more, and the light transmittance at wavelength 375 nm is 5% or less.

[7] The optical film according to [6], wherein the content of the ultraviolet absorber in the optical film is less than 1 part by mass relative to 100 parts by mass of the polyamideimide resin.

[8] The optical film according to [6] or [7], in which L is a divalent heterocyclic ring in formula (2b).

[9] A flexible display device comprising the optical film according to [5] or the optical film according to any one of [6] to [8].

[10] The flexible display device according to [9], further comprising a touch sensor.

[11] The flexible display device according to [9] or [10], further comprising a polarizing plate.

The polyamideimide resin of the present invention can form an optical film having excellent light resistance. Moreover, the optical film of this invention has excellent light resistance.

<Polyamideimide resin>

The polyamideimide resin of the present invention is represented by formulas (1) and (2)

[In formula (1) and formula (2), X each independently represents a divalent organic group, Y represents a tetravalent organic group, and Z represents a divalent heterocyclic ring]

It includes the structural unit represented by. Since the optical film containing the polyamideimide resin of the present invention contains the structural unit represented by formula (2), the polyamideimide resin can have excellent light resistance, and discoloration of the film by irradiation with ultraviolet rays It can be effectively suppressed. In addition, in this specification, the "structural unit" in a polyamideimide resin represents the repeating structural unit which comprises a polyamideimide resin. In addition, in this specification, "light-resistant" means the property which can suppress discoloration even if the optical film is exposed to ultraviolet light (light in the ultraviolet region).

In formula (2), Z represents a divalent heterocyclic ring. Examples of the divalent heterocyclic ring include a heterocyclic ring containing at least one hetero atom selected from the group of nitrogen atom, oxygen atom, and sulfur atom as a constituent atom of the ring. In the divalent heterocycle, a part or all of the hydrogen atoms of the heterocycle may be substituted with a substituent. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom, and the like. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, the aryl group having 6 to 12 carbon atoms, or the halogen atom include an alkyl group having 1 to 6 carbon atoms in R ^a and R ^b in the formula (a), and 1 to 6 carbon atoms. What was illustrated as an alkoxy group of 6, an aryl group of 6-12 carbons, or a halogen atom is mentioned. The bivalent heterocycle may be monocyclic or polycyclic, or in the case of polycyclic, a condensed heterocyclic ring in which a plurality of heterocyclic rings are condensed, or a condensed heterocyclic ring in which a heterocyclic ring and a hydrocarbon ring are condensed. The heterocycle may be non-aromatic, but is usually aromatic. The heterocyclic ring in the monocyclic structure or one heterocyclic ring in the polycyclic structure composed of a plurality of rings is preferably a 4 to 15 member ring, more preferably a 4 to 10 member ring, and more preferably 4 to 6 It is a torus. In one aspect of the present invention, the polyamideimide resin may include a plurality of species of the same or different Z.

As the divalent heterocyclic ring constituting Z, for example, a ring is formed from a sulfur atom-containing heterocycle such as a thiophene ring, a tetrahydrothiophene ring, a thianthrene ring, a thiazole ring, a thiadiazole ring, or a phenothiazine ring. A divalent heterocyclic ring containing a sulfur atom in which two hydrogen atoms among hydrogen atoms directly attached to a carbon atom or a hetero atom are removed; Two hydrogen atoms among the hydrogen atoms directly attached to the carbon atom or hetero atom constituting the ring are removed from an oxygen atom-containing heterocycle such as a benzopyran ring, a chroman ring, a furan ring, an isobenzofuran ring, or a phenoxazine ring. , A divalent heterocyclic ring containing an oxygen atom; Carbon atoms constituting the ring from nitrogen atom-containing heterocycles such as pyrrole ring, imidazole ring, pyridine ring, indole ring, quinoline ring, carbazole ring, acridine ring, piperidine ring, piperazine ring, morpholine ring, etc. Or a divalent heterocyclic ring containing a nitrogen atom, in which two hydrogen atoms are removed from a hydrogen atom directly bonded to a hetero atom, is mentioned. The divalent heterocycle constituting these Z can be used alone or in combination of two or more. Among these, a divalent heterocyclic ring containing a sulfur atom is preferable, and a divalent heteroaromatic ring containing a sulfur atom is more preferable from the viewpoint of easily improving the light resistance of the optical film.

In a preferred embodiment of the present invention, in formula (2), Z is formula (a)

[In the formula (a), R ^a and R ^b each independently 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, and R ^a and R ^b are They may be bonded to each other, and hydrogen atoms contained in R ^a and R ^b may be each independently substituted with a halogen atom, and * represents a bonding hand]

It is a divalent heterocyclic ring represented by. If Z is a divalent heterocyclic ring represented by formula (a), the optical film comprising the polyamideimide resin of the present invention can further improve light resistance.

R ^a and R ^b each independently 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 methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group and 2-methyl-butyl group. , 3-methylbutyl group, 2-ethyl-propyl group, n-hexyl group and the like.

Examples of the alkoxy group having 1 to 6 carbon atoms include, for example, methoxy group, ethoxy group, propyloxy group, isopropyloxy group, butoxy group, isobutoxy group, tert-butoxy group, pentyloxy group, hexyloxy group, cyclohexyloxy And timing. Further, R ^a and R ^b may be bonded (connected) to each other, and in this case, examples of the group formed by R ^a and R ^b include an ethylene dioxy group, a propylene dioxy group, and a dimethylpropylene dioxy group.

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 easy to improve the light resistance of the obtained optical film, R ^a and R ^b are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or preferably an aryl group having 6 to 12 carbon atoms, and a hydrogen atom or 1 to carbon atoms. It is more preferably an alkyl group of 3 or an aryl group having 6 to 8 carbon atoms, and more preferably a hydrogen atom, a methyl group, an ethyl group, or a phenyl group. Here, the hydrogen atom contained in R ^a and R ^b may be each independently substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In Formulas (1) and (2), X each independently represents a divalent organic group, preferably a divalent organic group having 4 to 40 carbon atoms, more preferably 4 to 40 carbon atoms having a cyclic structure. Represents a divalent organic group. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. In the organic group, the 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 of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8. The polyamideimide resin which is one embodiment of the present invention may contain a plurality of types of X, and the plurality of types of X may be the same or different from each other. As X, groups represented by formulas (10), (11), (12), (13), (14), (15), (16), (17) and (18) ; A group in which hydrogen atoms in the groups represented by the formulas (10) to (18) are substituted 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 is exemplified.

In formulas (10) to (18), * represents a bonding hand,

V ¹ , V ² and V ³ are each independently a single bond, -O-, -S-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO _2- , -CO- or -NQ. Here, Q represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom.

In one example, V ¹ and V ³ are a single bond, -O- or -S-, and V ² is -CH _2- , -C (CH ₃ ) _2- , -C (CF ₃ ) ₂ -or -SO _2- . The bonding position of each ring of V ¹ and V ² and the bonding position of each ring of V ² and V ³ are, for each ring, preferably a meta position or a para position, more preferably a para position. .

Among the groups represented by the formulas (10) to (18), from the viewpoint of easily increasing the light resistance, surface hardness, flexural resistance, and modulus of elasticity of the optical film, equations (13), (14), (15), and ( The group represented by 16) and formula (17) is preferable, and the group represented by formula (14), formula (15) and formula (16) is more preferable. Moreover, it is preferable that V ¹ , V ² and V ³ are each independently a single bond, -O- or -S-, from the viewpoint of easily increasing the light resistance, surface hardness, flexibility, etc. of the optical film, and single bond or It is more preferable that it is -O-.

In a preferred embodiment of the present invention, at least a portion of the plurality of Xs in formulas (1) and (2) are represented by formula (4):

[In the formula (4), R ¹⁰ to R ¹⁷ each independently 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, and R ¹⁰ to R ¹⁷ The hydrogen atom contained in each may be independently substituted with a halogen atom, and * represents a bond;

It is a group represented by. When at least a part of the plurality of Xs in the formulas (1) and (2) is a group represented by the formula (4), the optical film is liable to improve light resistance, modulus of elasticity, flexibility, and the like.

In formula (4), R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , and R ¹⁷ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, 1 to 6 carbon atoms It represents an alkoxy group of 6 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 are alkyl groups having 1 to 6 carbon atoms in R ^a and R ^b of formula (a), and alkoxy having 1 to 6 carbon atoms. What was illustrated as a group or a C6-C12 aryl group is mentioned. R ¹⁰ to R ¹⁷ each independently represent 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 R ¹⁰ to R ¹⁷ The hydrogen atom contained in each may be independently substituted with a halogen atom. As a halogen atom, what was illustrated as a halogen atom in R ^a and R ^b of Formula (a) is mentioned. R ¹⁰ to R ¹⁷ are each independently a hydrogen atom, a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group, more preferably from the viewpoint of easily increasing the light resistance, surface hardness and transparency of the optical film, particularly Preferably R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , and R ¹⁶ are hydrogen atoms, R ¹¹ and R ¹⁷ are hydrogen atoms, methyl groups, fluoro groups, chloro groups or trifluoromethyl groups, in particular R ¹¹ and It is preferable that R ¹⁷ is a methyl group or a trifluoromethyl group.

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

It is a group represented by, that is, at least a part of a plurality of X is a group represented by formula (4 '). In this case, the optical film tends to easily improve light resistance, modulus of elasticity, transparency, and the like, while improving the solubility of the polyamideimide resin in a solvent by a skeleton containing fluorine element, and lowering the viscosity of the resin varnish. It can also be suppressed to facilitate the processability of the film.

In a preferred embodiment of the present invention, X in the polyamideimide resin, preferably 30 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more of formula (4), in particular Equation (4 '). When X in the said range in the said polyamideimide resin is represented by Formula (4), especially Formula (4 '), an optical film tends to improve light resistance, elastic modulus, and transparency, and also contains a fluorine element. It improves the solubility of the polyamideimide resin in a solvent by the said skeleton, and can also suppress the viscosity of the resin varnish to be low to facilitate the processability of the film. Moreover, preferably, 100 mol% or less of X in the said polyamideimide resin is represented by Formula (4), especially Formula (4 '). X in the said polyamideimide resin may be a formula (4), especially (4 '). The ratio of the group represented by formula (4) of X in the polyamideimide resin can be measured, for example, using ¹ H-NMR, or can be calculated from the introduction ratio of the raw material.

In formula (1), Y each independently represents a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbon atoms, more preferably a tetravalent organic group having 4 to 40 carbon atoms having a cyclic structure. Group. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. The organic group is an organic group in which the 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 of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8 . The polyamideimide resin which is one embodiment of the present invention may contain a plurality of types of Y, and the plurality of types of Y may be the same or different from each other. As Y, the following formulas (20), (21), (22), (23), (24), (25), (26), (27), (28), and Group represented by formula (29); A group in which hydrogen atoms in the groups represented by the formulas (20) to (29) are substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; And a chain hydrocarbon group having a tetravalent carbon number of 6 or less is exemplified.

In equation (20) to equation (29),

* Represents a bonding hand,

W ¹ is a single bond, -O-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -Ar-, -SO _2- , -CO-, -O-Ar-O-, -Ar-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C (CH ₃ ) ₂ -Ar- Or -Ar-SO ₂ -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which the hydrogen atom may be substituted with a fluorine atom, and a phenylene group is mentioned as a specific example.

Among the groups represented by formulas (20) to (29), groups represented by formulas (26), (28), or (29) are preferred from the viewpoint of easily increasing the light resistance, flexibility, surface hardness, and transparency of the optical film. And the group represented by formula (26) is more preferable. Moreover, W ¹ is a single bond, -O-, -CH _2- , -CH ₂ -CH ₂ -,-each independently from the viewpoint of easy to increase flexibility and easy to reduce yellowness (YI value). It is preferred that CH (CH ₃ )-, -C (CH ₃ ) ₂ -or -C (CF ₃ ) _2- , single bond, -O-, -CH _2- , -CH (CH ₃ )-,- C (CH ₃ ) ₂ -or -C (CF ₃ ) ₂ -is more preferable, and single bond, -C (CH ₃ ) ₂ -or -C (CF ₃ ) ₂ -is more preferable.

In a preferred embodiment of the present invention, at least a portion of the plurality of Y in formula (1), formula (5):

[In the formula (5), R ¹⁸ to R ²⁵ each independently 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, and R ¹⁸ to R ²⁵ The hydrogen atom contained in each may be independently substituted with a halogen atom, and * represents a bond.]

It is a group represented by. If at least a part of the plurality of Ys in the formula (1) is a group represented by the formula (5), the optical film tends to easily improve light resistance, flexibility, and transparency, and at the same time, the solvent for the polyamideimide resin to the solvent. The solubility can be improved, and the viscosity of the resin varnish can be suppressed low to facilitate the processability of the film.

In formula (5), R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, 1 to 6 carbon atoms Represents an alkoxy group 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 are alkyl groups having 1 to 6 carbon atoms in R ^a and R ^b of formula (a), and alkoxy having 1 to 6 carbon atoms. What was illustrated as a group or a C6-C12 aryl group is mentioned. R ¹⁸ to R ²⁵ each independently represent 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 R ¹⁸ to R ²⁵ The hydrogen atom contained in each may be independently substituted with a halogen atom. As a halogen atom, what was illustrated as a halogen atom in R ^a and R ^b of Formula (a) is mentioned. R ¹⁸ to R ²⁵ are each independently, from the viewpoint of easily increasing the light resistance, flexibility and transparency of the optical film, and more preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and more Preferably R ¹⁸ , R ¹⁹ , R ²⁰ , R ²³ , R ²⁴ , and R ²⁵ are hydrogen atoms, R ²¹ and R ²² are hydrogen atoms, methyl groups, fluoro groups, chloro groups or trifluoromethyl groups, in particular It is preferable that R ²¹ and R ²² are methyl groups or trifluoromethyl groups.

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

It is a group represented by, that is, at least a part of a plurality of Y is a group represented by formula (5 '). In this case, it is easy to improve light resistance, surface hardness and transparency of the optical film.

In a preferred embodiment of the present invention, Y of the polyamideimide resin, preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more of formula (5), in particular Equation (5 '). When Y in the above range in the polyamideimide resin is represented by formula (5), particularly formula (5 '), the optical film comprising the polyamideimide resin tends to have high light resistance, transparency, and flexibility. In addition, the solubility of the polyamideimide resin in a solvent is improved by a skeleton containing an element of fluorine, and the viscosity of the resin varnish can be suppressed to be low, making the production of the film easy. Moreover, preferably, 100 mol% or less of Y in the said polyamideimide resin is represented by Formula (5), especially Formula (5 '). Y in the said polyamideimide resin may be a formula (5), especially (5 '). The ratio of the group represented by formula (5) of Y in the polyamideimide resin can be measured, for example, using ¹ H-NMR, or can be calculated from the introduction ratio of the raw material.

In a preferred embodiment of the present invention, in the polyamideimide resin of the present invention, the content of the structural unit represented by formula (2) is 0.1 mol or more, more preferably 1 mole of the structural unit represented by formula (1). 0.5 mol or more, more preferably 1.0 mol or more, particularly preferably 1.5 mol or more, preferably 10.0 mol or less, more preferably 6.0 mol or less, more preferably 5.0 mol or less, particularly preferably It is 4.5 mol or less, and any combination of these upper and lower limits may be used. When the content of the structural unit represented by formula (2) is greater than or equal to the above lower limit, the optical film tends to exhibit higher light resistance. Moreover, when the content of the structural unit represented by Formula (2) is less than or equal to the above upper limit, the viscosity due to hydrogen bonding between the amide bonds in Formula (2) can be suppressed, and the viscosity of the varnish can be reduced, thereby making optical film production It becomes easy. Moreover, the content (ratio) of the structural unit represented by Formula (2) in polyamideimide resin can be measured using ¹ H-NMR, for example, or can be calculated from the introduction ratio of a raw material.

The polyamideimide resin of the present invention is represented by formula (2a)

[In formula (2a), X and K each independently represent a divalent organic group. Provided that K does not contain heterocycles]

The structural unit represented by may be further included.

In formula (2a), each of K is independently a divalent organic group, and preferably may be substituted with a C 1 to C 8 hydrocarbon group or a fluorine-substituted C 1 to C 8 hydrocarbon group. It is an organic group of ∼40, and more preferably has a cyclic structure of 4 to 6 carbon atoms, which may be substituted with 1 to 8 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, or a fluorine-substituted hydrocarbon group with 1 to 8 carbon atoms. It represents a divalent organic group of -40. An alicyclic structure and an aromatic ring structure are mentioned as a cyclic structure. As the organic group of K, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) And a group in which two nonadjacent groups are substituted with a hydrogen atom and a divalent chain hydrocarbon group having 6 or less carbon atoms among the bonding hands of the group represented by formula (29). From the viewpoint of easily suppressing the yellowness of the optical film (reducing the YI value), groups represented by formulas (22), (26), (28), and (29) are preferred, and (26), 28), Formula (29) is more preferable. In one embodiment of the present invention, each of the polyamideimide resins may include a plurality of types of K, and the plurality of types of K may be the same or different from each other.

In a preferred embodiment of the present invention, from the viewpoint of easy to improve the light resistance, elastic modulus, surface hardness, etc. of the optical film, at least a part of K in the formula (2a) is the formula (3)

(In formula (3), R ¹ to R ⁸ each independently 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, and R ¹ to R ⁸ are The hydrogen atoms contained may be each independently substituted with a halogen atom, and A is a single bond, -O-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO _2- , -S-, -CO- or -N (R ⁹ )-, and R ⁹ is substituted with a hydrogen atom or a halogen atom Represents a hydrocarbon group having 1 to 12 carbon atoms, m is an integer from 0 to 4, and * represents a bond)

It is preferable to include the group represented by.

In formula (3), A is, each independently, a single bond, -O-, -CH _2- , -CH ₂ -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , -SO _2- , -S-, -CO- or -N (R ⁹ )-, from the viewpoint of easy to improve light resistance, elastic modulus and surface hardness of the optical film, It preferably represents -O- or -S-, and more preferably represents -O-. R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 to 6 carbon atoms. 12 represents an aryl group. 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, the alkyl group having 1 to 6 carbon atoms in R ^a and R ^b in formula (2), the alkoxy having 1 to 6 carbon atoms What was illustrated above is mentioned as a group or a C6-C12 aryl group. From the viewpoint of easily improving the light resistance, modulus, and surface hardness of the optical film, R ¹ to R ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or It represents an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom. Here, the hydrogen atom contained in R ¹ to R ⁸ may be each independently substituted with a halogen atom. R ⁹ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a hydrogen atom or a halogen atom. Moreover, as X, the thing illustrated above as X of Formula (1) and Formula (2) is mentioned.

In Formula (3), m is an integer in the range of 0 to 4, and when m is within this range, light resistance, elastic modulus, surface hardness, and the like of the optical film tend to be improved. Moreover, in Formula (3), m is preferably an integer in the range of 0 to 3, more preferably an integer in the range of 0 to 2, more preferably 0 or 1, particularly preferably 1 . When m is within this range, the light resistance, modulus of elasticity, and surface hardness of the optical film tends to be improved, and the availability of raw materials is relatively good. Moreover, K may contain 1 type or 2 or more types of groups represented by Formula (3), and from the viewpoint of more easily improving light resistance, elastic modulus and surface hardness of the optical film, it is more preferable to include a group with m being 1 desirable.

In a preferred embodiment of the present invention, Formula (3) is Formula (3 '):

It is a group represented by, that is, at least a part of a plurality of K is a group represented by formula (3 '). In this case, the optical film is more likely to further improve light resistance, modulus, and surface hardness.

In a preferred embodiment in which the polyamideimide resin of the present invention includes a group represented by formula (3), m in formula (3) is 0 to 4, preferably 1 to 4, and the content of a group represented by formula (1) ) To the total molar amount of the structural unit represented by, the structural unit represented by formula (2), and the structural unit represented by formula (2a) (hereinafter, may be represented by structural units represented by formulas (1) to (2a)). With respect to, it is preferably 3 mol% or more, more preferably 5 mol% or more, more preferably 7 mol% or more, particularly preferably 9 mol% or more, preferably 90 mol% or less, more preferably 70 mol% or less, more preferably 50 mol% or less, particularly preferably 30 mol% or less, and any combination of these upper and lower limits may be used. When the group represented by m in the formula (3) is 0 to 4, preferably 1 to 4 or more, the optical film tends to improve light resistance, modulus of elasticity, surface hardness, and the like. If the group represented by m in Formula (3) is 1 to 4 is equal to or less than the above upper limit, the viscosity of the resin varnish can be suppressed by suppressing the thickening due to hydrogen bonding between the amide bonds derived from Formula (3). Processing can be facilitated.

In a preferred embodiment of the present invention, the content of the structural unit represented by formula (2) in the polyamideimide resin is preferably 20 mol with respect to the total molar amount of the structural units represented by formulas (1) to (2a). % Or more, more preferably 30 mol% or more, more preferably 40 mol% or more, particularly preferably 50 mol% or more, most preferably 60 mol% or more, preferably 90 mol% or less, more preferably Preferably, it is 85 mol% or less, more preferably 80 mol% or less, and any combination of these upper and lower limits may be used. When the structural unit represented by Formula (2) in the polyamideimide resin is within the above range, light resistance of the optical film is more easily improved.

The polyamideimide resin may further include a structural unit represented by formula (30) and / or a structural unit represented by formula (31).

In Formula (30), Y ¹ is each independently a tetravalent organic group, and preferably an organic group in which the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ¹ , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula A group represented by (29), a group in which the hydrogen atom in the groups represented by the formulas (20) to (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and a tetravalent C 6 or less chain type hydrocarbon Gi is illustrated. One embodiment of the polyamide-imide resin of the present invention, may include a plurality of types of Y ^1, Y ¹ may be a plurality of types it is be the same or different from each other.

In formula (31), Y ² is a trivalent organic group, preferably an organic group in which the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ² , formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula A group in which any one of the bonds of the group represented by (29) is substituted with a hydrogen atom, and a trivalent carbon group having 6 or less carbon atoms are exemplified. One embodiment of the polyamide-imide resin of the present invention, may include a plurality of types of Y ^2, Y ² is a plurality of types, and may be the same or different from each other.

In Formulas (30) and (31), X ¹ and X ² are each independently a divalent organic group, and preferably, even if the hydrogen atom in the organic group is substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is an organic group. As X ¹ and X ² , Formula (10), Formula (11), Formula (12), Formula (13), Formula (14), Formula (15), Formula (16), Formula (17), and Formula ( Group represented by 18); A group in which hydrogen atoms in the groups represented by the formulas (10) to (18) are substituted 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 is exemplified.

In one embodiment of the present invention, the polyamideimide resin is, in addition to the structural units represented by the formulas (1) and (2), if necessary, the structural units represented by the formula (2a), represented by the formula (30) And at least one structural unit selected from structural units and structural units represented by formula (31). From the viewpoint of easy to improve the light resistance of the optical film, in the polyamideimide resin, the total content of the structural units represented by formulas (1) to (2a) is the total molar amount of all the structural units constituting the polyamideimide resin. Based on this, it is preferably 80 mol% or more, more preferably 90 mol% or more, more preferably 95 mol% or more, particularly preferably 99 mol% or more, and usually 100 mol% or less. Moreover, content (ratio) of the structural unit represented by Formula (1)-Formula (2a) can be measured using ¹ H-NMR, for example, or can be calculated from the introduction ratio of a raw material.

The weight average molecular weight (Mw) of the polyamideimide resin is, in terms of standard polystyrene, preferably 100,000 or more, more preferably 150,000 or more, more preferably 200,000 or more, particularly preferably 250,000 or more, and especially 300,000 or more , Preferably 1,000,000 or less, more preferably 900,000 or less, and any combination of these upper and lower limits may be used. When the Mw of the polyamideimide resin is equal to or more than the above lower limit, the flexibility, surface hardness and elastic modulus of the optical film are likely to be improved, and when the Mw is less than or equal to the above upper limit, the gel of the resin varnish is easily suppressed, thereby obtaining Transparency and appearance tend to be good. In addition, Mw can be measured by gel permeation chromatography (GPC), for example, by the method described in Examples.

<Method for producing polyamideimide resin>

The polyamideimide resin of the present invention can be produced using a tetracarboxylic acid compound, a dicarboxylic acid compound and a diamine compound as main raw materials, and includes, for example, structural units represented by formulas (1) and (2). The polyamide-imide resin contained is a step of reacting a diamine compound represented by formula (6) with a tetracarboxylic acid compound represented by formula (7) to produce a polyamic acid, the polyamic acid and dicar represented by formula (8) It can be produced by a method including a step of reacting a carboxylic acid compound to produce a polyamideimide precursor, and a step of imidizing the polyamideimide precursor.

[In formula (6), formula (7), and formula (8), X corresponds to X in formula (1) and formula (2), Y corresponds to Y in formula (1), Z corresponds to Z in formula (2), and R ^c and R ^d are each independently -OH, -OMe, -OEt, -OPr, -OBu or -Cl]

In the said manufacturing method, when a dicarboxylic acid compound represented by Formula (9) is further used as a dicarboxylic acid compound, the polyamideimide resin containing the structural unit represented by Formula (1)-Formula (2a) Can be produced.

[In formula (9), K corresponds to K in formula (2a), and R ^e and R ^f are each independently -OH, -OMe, -OEt, -OPr, -OBu or -Cl]

Specifically, examples of the diamine compound include aliphatic diamines, aromatic diamines, and mixtures thereof. In addition, in this embodiment, "aromatic diamine" refers to the diamine in which the amino group is directly bonded to the aromatic ring, and may contain an aliphatic group or other substituents 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 are not limited thereto. Among these, it is preferably a benzene ring. Moreover, "aliphatic diamine" refers to the diamine in which the amino group is directly bonded to the aliphatic group, and may include an aromatic ring or other substituents in a part of the structure. The diamine compounds may be used alone or in combination of two or more.

Specific examples of the aliphatic diamine include acyclic aliphatic diamines such as 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 two or more.

Specific examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,6-dia Aromatic diamines having one aromatic ring such as minonaphthalene; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-dia Minodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis (4-aminophenoxy) Benzene, 1,3-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2- Bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2'-dimethylbenzidine, 2,2'-bis (tri Fluoromethyl) benzidine (sometimes referred to as TFMB), 4,4'-bis (4-aminophenoxy) biphenyl, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene, 9,9-bis (4-amino-3-chlorophenyl) fluorene, 9,9-bis (4-amino-3-fluorophenyl) fluorene, etc. , Aromatic diamine having two or more aromatic rings Can. These can be used alone or in combination of two or more.

The aromatic diamine is preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, and 3,3'-diaminodiphenyl ether. , 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] Sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) ) Phenyl] propane, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl, 4,4'-bis (4-aminophenoxy) ratio Phenyl, more preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone , 1,4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2 , 2'-dimethylbenzidine, 2,2'-bis ( Trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl. These can be used alone or in combination of two or more.

Among the above diamine compounds, it is preferable to use at least one selected from the group consisting of aromatic diamines having a biphenyl structure from the viewpoint of improving light resistance, surface hardness or transparency of the optical film. Consisting of 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-bis (4-aminophenoxy) biphenyl and 4,4'-diaminodiphenyl ether It is more preferable to use at least one selected from the group, and more preferably to use 2,2'-bis (trifluoromethyl) benzidine.

The tetracarboxylic acid compound represents a tetracarboxylic acid or tetracarboxylic acid derivative. Tetracarboxylic acid derivatives include anhydrides of tetracarboxylic acids, preferably dianhydrides, acid chlorides, and the like. As a tetracarboxylic-acid compound, For example, aromatic tetracarboxylic-acid compound, such as aromatic tetracarboxylic acid and its anhydride, Preferably its dianhydride; Aliphatic tetracarboxylic acid compounds, such as aliphatic tetracarboxylic acid and its anhydride, Preferably its dianhydride, etc. are mentioned. These tetracarboxylic acid compounds may be used alone or in combination of two or more.

Specific examples of the aromatic tetracarboxylic dianhydride include non-condensed polycyclic aromatic tetracarboxylic dianhydride, monocyclic aromatic tetracarboxylic dianhydride, and condensed polycyclic aromatic tetracarboxylic dianhydride. As a non-condensed polycyclic aromatic tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 2,2', 3 , 3'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (sometimes referred to as BPDA), 2,2', 3,3 ' -Biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2, 2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 '-(hexafluoroisopropylidene) di Phthalic dianhydride (sometimes referred to as 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, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride , Bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4 '-(p-phenylenedioxy) diphthalic dianhydride and 4,4' and-(m-phenylenedioxy) diphthalic dianhydride. Moreover, 1,2,4,5-benzenetetracarboxylic dianhydride is mentioned as monocyclic aromatic tetracarboxylic dianhydride, and as a condensed polycyclic aromatic tetracarboxylic dianhydride, it is 2,3 And 6,7-naphthalenetetracarboxylic dianhydride.

Among these, preferably 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-benzophenonetetracar Carboxylic acid dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4, 4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2 , 2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, 1,2-bis (2,3-dicarboxyphenyl ) Ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4) -Dicarboxyphenyl) ethane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4 '-(p-phen And rendioxy) diphthalic dianhydride and 4,4 '-(m-phenylenedioxy) diphthalic dianhydride, more preferably 4,4'-oxydiphthalic dianhydride, 3,3', 4 , 4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride, Bis (3,4-dicarboxyphenyl) methane dianhydride and 4,4 '-(p-phenylenedioxy) diphthalic acid dianhydride. These can be used alone or in combination of two or more.

As an aliphatic tetracarboxylic dianhydride, a cyclic or acyclic aliphatic tetracarboxylic dianhydride is mentioned. The cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2, Cycloalkane tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7, such as 3,4-cyclobutanetetracarboxylic dianhydride and 1,2,3,4-cyclopentanetetracarboxylic dianhydride -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 two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride, and the like, These can be used alone or in combination of two or more. Moreover, you may use combining a cyclic aliphatic tetracarboxylic dianhydride and a non-cyclic aliphatic tetracarboxylic dianhydride.

Among the tetracarboxylic acid compounds, the alicyclic tetracarboxylic dianhydride or the non-condensed polycyclic aromatic tetracarboxylic dianhydride is preferred from the viewpoint of improving light resistance, surface hardness, or transparency of the optical film. As a specific example, 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride Water, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis (3,4 -Dicarboxyphenyl) propane dianhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride and mixtures thereof are preferred, 3,3', 4,4'-biphenyltetracarboxylic acid Dihydrate and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride and mixtures thereof are more preferred, and 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride is more preferred. .

The dicarboxylic acid compound represents a dicarboxylic acid or a dicarboxylic acid derivative, and examples of the dicarboxylic acid derivative include acid chlorides and ester bodies of the dicarboxylic acid. The dicarboxylic acid compounds may be used alone or in combination of two or more.

As specific examples of the dicarboxylic acid compound, for example, 2,5-thiophendicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclo Hexanedicarboxylic acid, 4,4'-oxybisbenzoic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, two cyclohexanecarboxylic acids or two benzoic acid single bond, -CH _2- , -C (CH ₃ ) _{2 -, -C (CF 3)} 2 -, -SO 2 - or an alicyclic dicarboxylic acid or aromatic dicarboxylic acids and their derivatives (e.g. acid chloride, acid anhydride), such as phenylene groups linked compound ; And aliphatic dicarboxylic acids such as dicarboxylic acid compounds of chain hydrocarbons having 8 or less carbon atoms and their derivatives (for example, acid chlorides and esters). These dicarboxylic acid compounds may be used alone or in combination of two or more. Among these, 2,5-thiophenedicarboxylic acid or a derivative thereof, especially 2,5-thiophenedicarboxylic acid chloride (sometimes referred to as TDOC) is preferable from the viewpoint of easy to obtain good light resistance of the optical film. Do.

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

In the production of the polyamideimide resin, the reaction temperature of the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound is not particularly limited, but is, for example, 20 to 200 ° C, preferably 25 to 100 ° C. The reaction time is not particularly limited, but is, for example, about 30 minutes to 10 hours. If necessary, the reaction may be performed under an inert atmosphere or a reduced pressure condition. In a preferred aspect, the reaction is performed while stirring under normal pressure and / or an inert gas atmosphere. Moreover, it is preferable to perform reaction in a solvent inert to reaction. The solvent is not particularly limited as long as it does not affect the reaction, but, for example, water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy- Alcohol-based solvents such as 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-based solvents such as tetrahydrofuran and dimethoxyethane; Chlorine-containing solvents such as chloroform and chlorobenzene; Amide solvents such as N, N-dimethylacetamide (DMAc) and N, N-dimethylformamide (DMF); Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; Carbonate-based solvents such as ethylene carbonate and propylene carbonate; And combinations thereof (mixed solvents). Among these, an amide solvent can be suitably used from the viewpoint of solubility.

In the imidation step in the production of the polyamideimide resin, imidization can be performed in the presence of an imidization catalyst. Examples of the imidization catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine and ethyldibutylamine; Alicyclic amines (monocyclic) such as N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine; Alicyclic amines (polycyclic) such as azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2.2] octane, and azabicyclo [3.2.2] nonane; And pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline), 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine And aromatic amines such as 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline. . Moreover, it is preferable to use an acid anhydride with an imidation catalyst from a viewpoint which is easy to accelerate an imidation reaction. Examples of the acid anhydride include conventional acid anhydrides used 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 acid.

The polyamide-imide resin obtained by imidization is isolated (separated and purified) by a conventional method such as separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a combination of these separation means. Alternatively, in a preferred embodiment, a polyamideimide resin may be precipitated by adding a large amount of alcohol, such as methanol, to the reaction solution containing the polyamideimide resin, and may be isolated by concentration, filtration, drying, or the like. .

<Optical film (A)>

The present invention includes an optical film (sometimes referred to as an optical film (A)) comprising the polyamideimide resin of the present invention. Since the optical film comprising the polyamideimide resin of the present invention has excellent light resistance, even if exposed to ultraviolet light, discoloration of the film can be effectively suppressed. In addition, the optical film also has excellent transparency. For this reason, it can be suitably used for a member of an image display device, such as a liquid crystal display device or an organic EL display device, especially a front panel (window film) of a flexible display. The front plate has a function of protecting the image display element in the flexible display. More specifically, examples of the image display device include televisions, smart phones, mobile phones, car navigation systems, tablet PCs, portable game machines, electronic papers, indicators, bulletin boards, watches, and wearable devices such as smart watches. Examples of the flexible display include an image display device having flexible characteristics, for example, a television, a smart phone, a mobile phone, a car navigation system, a tablet PC, a portable game machine, electronic paper, an indicator, a bulletin board, a clock, and a wearable device.

In one embodiment of the present invention, when the optical film of the present invention is applied to a flexible display device, deterioration such as discoloration due to ultraviolet rays can be suppressed, so that the life of the display device can be increased. For this reason, generation of CO ₂ due to disposal of the display device can be suppressed.

The content of the polyamideimide resin in the optical film is preferably 40% by mass or more, more preferably 60% by mass or more, and more preferably 80% by mass with respect to the mass of the optical film, from the viewpoint of easy to express good light resistance. % Or more, particularly preferably 90% by mass or more, and particularly 95% by mass or more. The upper limit of the content of the polyamideimide resin is 100% by mass or less.

The optical film may further contain inorganic materials such as inorganic particles. Examples of the inorganic material include inorganic particles such as titania particles, alumina particles, zirconia particles, and silica particles, and silicon compounds such as quaternary alkoxysilanes such as tetraethyl orthosilicate. From the viewpoint of stability of the polyamideimide varnish for producing the optical film, it is preferred that the inorganic material is inorganic particles, particularly silica particles. The inorganic particles may be bound by a molecule having a siloxane bond.

The average primary particle size of the inorganic particles is, for example, from the viewpoint of transparency of the optical film, mechanical properties, and suppression of aggregation of the inorganic particles, for example, 1 to 100 nm, preferably 5 to 80 nm, and more preferably 7 to 50 nm. , Particularly preferably 10 to 30 nm. The average primary particle diameter can be determined by measuring the 10-point average value of the forward diameter by a transmission electron microscope.

When the optical film contains an inorganic material, the content is preferably 0.001 to 90% by mass, more preferably 0.01 to 60% by mass, more preferably 5 to 40 based on the total mass of the optical film. It is mass%. When the content rate of the inorganic material is within the above range, there is a tendency that the transparency and mechanical properties of the optical film are easily compatible.

The optical film may further contain an ultraviolet absorber. The ultraviolet absorber can be appropriately selected from those commonly used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light having a wavelength of 400 nm or less. Examples of the ultraviolet absorber include at least one compound selected from the group consisting of benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds, and triazine-based compounds. The ultraviolet absorbers may be used alone or in combination of two or more. In the present specification, the term “based compound” refers to a derivative of a compound in which the “based compound” is included. For example, the term "benzophenone-based compound" refers to a compound having a benzophenone as a parent skeleton and a substituent bound to benzophenone.

Normally, deterioration of the polyamideimide resin is suppressed by containing an ultraviolet absorber in the optical film. On the other hand, the optical film comprising the polyamideimide resin of the present invention may contain an ultraviolet absorber as described above, but can exhibit excellent light resistance even if it does not contain an ultraviolet absorber. For this reason, the content of the ultraviolet absorber can be preferably less than 1 part by mass, more preferably 0.5 part by mass or less, and even more preferably 0.1 part by mass or less with respect to 100 parts by mass of the optical film.

The optical film may further contain additives other than inorganic materials and ultraviolet absorbers. Examples of other additives include antioxidants, mold release agents, stabilizers, bluening agents, flame retardants, pH adjusting agents, silica dispersants, lubricants, thickeners, and leveling agents. When other additives are contained, the content is preferably 0.005 to 20% by mass, more preferably 0.01 to 15% by mass, and more preferably about 0.1 to 10% by mass relative to the mass of the optical film.

The thickness of the optical film can be appropriately selected depending on the application, preferably 25 μm or more, more preferably 30 μm or more, preferably 100 μm or less, more preferably 80 μm or less, more preferably 60 μm or less, and these Any combination of an upper limit and a lower limit may be used. The thickness of the optical film can be measured, for example, using a micrometer.

The yellowness of the optical film is preferably 8 or less, more preferably 5 or less, more preferably 3 or less, particularly preferably 2 or less, particularly preferably 1 or less. When the yellowness of the optical film is equal to or less than the above upper limit, the transparency becomes good, and when used in the front plate of an image display device, for example, it can contribute to high visibility. Moreover, yellowness is -5 or more normally, Preferably it is -2 or more. In addition, the yellowness (YI value) was measured for transmittance of 300-800 nm light using an ultraviolet visible near-infrared spectrophotometer to obtain a tristimulus value (X, Y, Z), and YI = 100 × (1.2769X). -1.0592Z) / Y.

The amount of change (ΔYI) of the yellowness before and after the light resistance test of the optical film is preferably 2.5 or less, more preferably 2.0 or less, further preferably 1.5 or less, particularly preferably 1.0 or less. The light resistance test is a test in which the film is continuously irradiated with ultraviolet light for 24 hours, and the measurement of YI can be measured in the same manner as the measurement method of yellowness. ΔYI can be measured, for example, by the method described in Examples.

In the optical film, the total light transmittance at a thickness of 50 μm is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. When the total light transmittance is equal to or more than the above lower limit, the transparency becomes good, and for example, when used for the front plate of an image display device, it can contribute to high visibility. In addition, the upper limit of the total light transmittance is usually 100% or less. In addition, the total light transmittance can be measured by using a haze computer according to JIS K 7105: 1981, for example, and can be measured by the method described in Examples.

The haze of the optical film is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less. When the haze of the optical film is equal to or less than the above upper limit, the transparency becomes good, and when used, for example, in the front plate of an image display device, it can contribute to high visibility. Moreover, the lower limit of haze is usually 0.01% or more. In addition, haze can be measured with a haze computer, for example.

<Method for manufacturing optical film (A)>

The optical film comprising the polyamideimide resin of the present invention is not particularly limited, but is, for example, the following steps:

(a) a step of preparing a liquid (which may be referred to as a polyamideimide varnish) containing the polyamideimide resin (varnish preparation step),

(b) a step of applying a polyamideimide varnish to the substrate to form a coating film (coating step), and

(c) Process of drying the applied liquid (coating film) to form an optical film (film forming process)

It can be manufactured by a method comprising a.

In the varnish preparation step, the polyamideimide varnish is prepared by dissolving the polyamideimide resin in a solvent and adding and stirring the above additives as necessary.

The solvent used for the preparation of the varnish is not particularly limited as long as it can dissolve the polyamideimide resin. As such a solvent, the solvent illustrated by the term of the <manufacturing method of polyamide imide resin> is mentioned, for example. Among these solvents, an amide solvent or a lactone solvent can be suitably used. These solvents may be used alone or in combination of two or more. The solid content concentration of the polyamideimide varnish is preferably 1 to 25% by mass, more preferably 5 to 15% by mass.

In the coating step, a polyamideimide varnish is coated on a substrate by a known coating method to form a coating film. As a known coating method, for example, a roll coating method such as a wire bar coating method, reverse coating, gravure coating, die coating method, comma coating method, lip coating method, spin coating method, screen coating method, fountain coating method, di And a ping method, a spraying method, and a flexible molding method.

In a film formation process, an optical film can be formed by drying and peeling a coating film from a base material. You may provide the process of drying an optical film further after peeling. The coating film can be dried usually at a temperature of 50 to 350 ° C. If necessary, the coating film may be dried under an inert atmosphere or under reduced pressure.

Examples of the substrate include metal belts such as SUS, and resin films such as PET films, PEN films, polyimide films, polyamide films, and other polyamideimide films. Among them, from the viewpoint of excellent heat resistance, a PET film, a PEN film, and the like are preferred, and a PET film is more preferred from the viewpoint of adhesion, ease of peeling, and cost when forming an optical film.

<Optical film (B)>

The present invention, formula (1) and formula (2b)

[In formula (1) and formula (2b), X and L each independently represent a divalent organic group, and Y represents a tetravalent organic group]

The polyamide-imide resin containing the structural unit represented by,

And an optical film (sometimes referred to as an optical film (B)) having a light transmittance of 70% or more at a wavelength of 420 nm and a light transmittance of 5% or less at a wavelength of 375 nm. Since the optical film of the present invention has a transmittance of 70% or more at a wavelength of 420 nm and a transmittance of 5% or less at a wavelength of 375 nm, ultraviolet light can be effectively absorbed, and excellent light resistance can be exhibited.

From the viewpoint of easily improving the light resistance of the optical film, the light transmittance at wavelength 420 nm is preferably 80% or more, more preferably 85% or more, and the light transmittance at wavelength 375 nm is preferably 3% or less And more preferably 1% or less. In addition, the light transmittance can be measured using an ultraviolet visible near-infrared spectrophotometer, and can be measured, for example, by the method described in Examples.

The structural unit represented by Formula (1) constituting the polyamideimide resin is the same as the structural unit represented by Formula (1) described in the section of <Polyamideimide Resin>.

In formula (2b), L is each independently represented by L1 or L2. L1 is the same as Z in Formula (2), and L2 is a divalent organic group excluding Z. L2 is preferably an organic group having 4 to 40 carbon atoms, which may be substituted with a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a fluorine-substituted hydrocarbon group having 1 to 8 carbon atoms, more preferably It shows a C4-C40 divalent organic group which has a cyclic structure which may be substituted with a C1-C8 hydrocarbon group or a fluorine-substituted C1-C8 hydrocarbon group. An alicyclic ring or an aromatic ring is mentioned as a cyclic structure. As an organic group of L2, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) And a group in which two nonadjacent groups are substituted with a hydrogen atom, and a divalent chain hydrocarbon group having 6 or less carbon atoms, among the bonding hands of the group represented by formula (29). Among these, if L1 (bivalent heterocyclic ring) is employed as L, it is easy to adjust the transmittance at a wavelength of 420 nm to 70% or more and the transmittance at a wavelength of 375nm to 5% or less. Moreover, the preferable divalent heterocyclic ring corresponding to L1 is also the same as the preferred one for Z described in <polyamideimide resin>, that is, as L1, a divalent heterocyclic ring containing a sulfur atom is preferable, and the formula (a) The divalent heterocyclic ring represented by) is more preferable. In one embodiment of the present invention, each of the polyamideimide resins may contain a plurality of types of L, and the plurality of types of L may be the same or different from each other.

In the optical film of the present invention, in order to adjust the transmittance at a wavelength of 420 nm to 70% or more and the transmittance at a wavelength of 375 nm to 5% or less, a method of containing an ultraviolet absorber having absorbance at a wavelength of 370 to 400 nm You may employ. However, since the optical film of the present invention can exhibit excellent light resistance even if it does not contain a UV absorber by using a polyamideimide resin containing a structural unit represented by formula (2), the content of the UV absorber is With respect to 100 parts by mass, preferably less than 1 part by mass, more preferably 0.5 parts by mass or less, still more preferably 0.1 parts by mass or less, particularly preferably 0 parts by mass. As an ultraviolet absorber, the ultraviolet absorber of the <optical film (A)> is mentioned.

In addition, since the optical film of the present invention is also excellent in heat resistance, it is possible to maintain excellent light resistance even when exposed to a high temperature environment, so that discoloration of the film can be effectively suppressed.

The optical film of the present invention may further contain an inorganic material, other additives, and the like, in addition to the ultraviolet absorber. Examples of the inorganic material or other additives include the inorganic material or other additives described in the section of <Optical Film (A)>. As for content of the inorganic material or other additives, the content described in the section of <Optical Film (A)> can also be adopted.

The production of the polyamideimide resin and the production of the optical film can be performed with reference to the above <Production of the polyamideimide resin> and the <Production method of the optical film (A)>.

<Laminate>

The optical film of the present invention may be a single layer or a laminate, or the optical film of the present invention may be used as it is, or may be used as a laminate with another film or layer. In the present invention, when the optical film is a laminate, it is called an optical film including all layers laminated on one side or both sides of the optical film. Further, for convenience, the optical film in the form of a laminate may be referred to as a laminate.

When the optical film of the present invention is a laminate, one or more functional layers may be provided on at least one surface of the optical film. Examples of the functional layer include an ultraviolet absorbing layer, a hard coating layer, a primer layer, a gas barrier layer, an adhesive layer, a color adjustment layer, and a refractive index adjustment layer. The functional layers can be used alone or in combination of two or more.

The optical film of the present invention can be a laminate with a protective film or the like shown below. That is, the optical film of the present invention may include a protective film or the like on at least one surface. When a functional layer is provided on one or both surfaces of the optical film, a protective film may be provided on the surface of the functional layer.

The protective film is affixed to the surface without the support of the optical film. When winding up a laminated body in roll shape, when there is a problem with winding property, such as blocking, in addition to the above, you may stick a protective film on the surface opposite to the optical film of a support body. The protective film bonded to the optical film is a film for temporarily protecting the surface of the optical film, and is not particularly limited as long as it is a peelable film capable of protecting the surface of the optical film. For example, polyester resin films, such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; And polyolefin-based resin films such as polyethylene and polypropylene films, and acrylic-based resin films, and are preferably selected from the group consisting of polyolefin-based resin films, polyethylene terephthalate-based resin films, and acrylic-based resin films. When a protective film is included on both surfaces of a layered product (optical film), the protective films on each surface may be the same or different from each other.

Although the thickness of a protective film is not specifically limited, Usually, it is 10-100 micrometers, Preferably it is 10-80 micrometers, More preferably, it is 10-50 micrometers. When a protective film is included on both surfaces of a laminate (optical film), the thickness of the protective film on each surface may be the same or different.

(Laminated film roll)

In this specification, the layered product (for example, a support, an optical film, and a protective film if necessary) is wound in a roll form on a winding core and is called a laminate film roll. In the case of continuous production, the laminate film roll is often stored in the form of a film roll once from space and other constraints, and the laminate film roll is one of them. In the form of a laminate film roll, since the laminate is more strongly wound, the cause of cloudiness on the support is easily transferred onto the optical film. However, when the support having a predetermined logarithmic contact angle of the present invention is used, the cloudiness from the support is difficult to transfer to the optical film, and even if it is wound with a laminate film roll, cloudiness is unlikely to occur.

As a material constituting the core of the laminated film roll, for example, polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyester resin, epoxy resin, phenol resin, melamine resin, silicon resin, polyurethane resin, polycarbonate resin , ABS resin and other synthetic resins; Metals such as aluminum; And fiber-reinforced plastics (FRP: composite materials containing fibers such as glass fibers in plastics to improve strength) and the like. The winding core has a shape such as a cylindrical shape or a cylindrical shape, and its diameter is, for example, 80 to 170 mm. Moreover, although the diameter (diameter after winding) of a film roll is not specifically limited, Usually, it is 200-800 mm.

<Flexible display device>

The present invention includes a flexible display device provided with the optical film. The flexible display device (optical laminate) may further include one layer selected from the group consisting of a polarizing plate and a touch sensor on one surface of the optical film. That is, the flexible display device of the present invention may further include a touch sensor and / or a polarizing plate. As described above, in the flexible display device, the optical film of the present invention is used as a front plate (window film). Therefore, the optical film of the present invention is sometimes called a window film. The window film may be provided with a window hard coating layer. In addition, the window film may be provided with a polarizing plate or a touch sensor with a point adhesive layer therebetween, if necessary.

At least one surface of the window film or the polarizing plate may be provided with a colored light-shielding pattern printed around an edge, and the light-shielding pattern may be in the form of a single layer or multiple layers. In addition, a polarizing plate may be bonded to one surface of the window film directly or with a point adhesive layer therebetween. For example, the polarizing plate may be continuously extended over the non-display area or the bezel portion, and may be a conventional polarizing plate including a polyvinyl alcohol-based polarizer and a protective film attached to at least one surface of the polyvinyl alcohol-based polarizer. do.

As an aspect of the present invention, the polarizing plate and the touch sensor are integrated on one surface of the window film, and the arrangement order of the polarizing plate and the touch sensor is not limited, and may be arranged in the order of the window film, polarizing plate, touch sensor and display panel. It may be arranged in the order of a window film, a touch sensor, a polarizing plate, and a display panel. When arranged in the order of a window film, a polarizing plate, a touch sensor, and a display panel, when the image display device is viewed from the viewing side, the touch sensor is located on the lower side of the polarizing plate, so that the pattern of the touch sensor is difficult to be seen. In this case, it is preferable that the front phase difference of the substrate of the touch sensor is ± 2.5 nm or less. As such a material, a non-stretched film may be, for example, a film of at least one material selected from the group consisting of materials such as triacetyl cellulose, cycloolefin, cycloolefin copolymer, and polynorbornene copolymer. On the other hand, only the pattern without the substrate of the touch sensor may have a structure transferred to the window film and the polarizing plate.

The polarizing plate and the touch sensor can be disposed between the window film and the display panel by a transparent adhesive layer or a transparent adhesive layer, but a transparent adhesive layer is preferred. When arranged in the order of a window film, a polarizing plate, a touch sensor, and a display panel, a transparent adhesive layer may be positioned between the window film and the polarizing plate, and between the touch sensor and the display panel. When arranged in the order of a window film, a touch sensor, a polarizing plate, and a display panel, a transparent adhesive layer may be positioned between the window film and the touch sensor, between the touch sensor and the polarizing plate, and between the polarizing plate and the display panel.

The thickness of the transparent adhesive layer is not particularly limited, and may be, for example, 1 to 100 μm. In the transparent adhesive layer according to the present invention, the thickness of the lower adhesive layer is greater than or equal to the thickness of the upper adhesive layer, and it is preferable that the viscoelasticity is 0.2 MPa or less at -20 to 80 ° C. In this case, noise generated due to interference between the touch sensor and the display panel can be reduced, and interfacial stress at the time of bending can be relaxed to suppress destruction of the upper and lower substrates. From the viewpoint of suppressing the cohesive failure of the pressure-sensitive adhesive and relaxing the interfacial stress, more preferably, the viscoelasticity may be 0.01 to 0.15 MPa.

(Polarizing plate)

The polarizing plate laminated on the window film may be configured with a polarizer alone or a polarizer and a protective film attached to at least one surface thereof. The thickness of the polarizing plate is not particularly limited, and may be, for example, 100 μm or less. If the thickness is 100 μm or less, flexibility is unlikely to decrease. Within the above range, for example, 5 to 100 μm may be sufficient.

The polarizer may be a film-type polarizer commonly used in the art produced by a process including steps such as swelling, dyeing, crosslinking, stretching, washing, drying a polyvinyl alcohol-based film, and as another example, It can be formed by applying a composition for liquid crystal coating as a polarizing coating layer. The composition for liquid crystal coating, as a coating layer forming composition, may include a polymerizable liquid crystal compound and a dichroic dye. The polarizing coating layer is, for example, by applying an alignment film forming composition on a substrate, to give an alignment to form an alignment film, and by applying a coating layer forming composition comprising a liquid crystal compound and a dichroic dye on the alignment film to form a liquid crystal coating layer Can be produced. Such a polarizing coating layer can form a thinner thickness than a polarizing plate including a protective film affixed by an adhesive on both sides of a polyvinyl alcohol-based polarizer. The thickness of the polarizing coating layer is usually 0.5 to 10 μm, preferably 2 to 4 μm.

(Orientation film forming composition)

The alignment film forming composition may include an alignment agent, a photopolymerization initiator, and a solvent commonly used in the art. As the above-mentioned alignment agent, an alignment agent commonly used in the art can be used without particular limitation. For example, a polyacrylate-based polymer, a polyamic acid, a polyimide-based polymer, or a polymer containing a cinnamate group can be used as the alignment agent, and when photo-alignment is applied, it is preferable to use a polymer containing a cinnamate group. Do.

The coating of the alignment layer forming composition may include, for example, spin coating, extrusion molding, dip coating, flow coating, spray coating, roll coating, gravure coating, micro gravure coating, and in-line coating. After the alignment film forming composition is applied and dried as necessary, an alignment treatment is performed. Various methods well known in the art can be employed for the alignment treatment, and preferably, photo-alignment film formation can be used. The photo-alignment film is usually obtained by applying a composition for forming a photo-alignment film containing a polymer or monomer having a photoreactive group and a solvent to a substrate, and irradiating polarized light (preferably polarized UV light). The photo-alignment film is more preferable in that the direction of the orientation regulating force can be arbitrarily controlled by selecting the polarization direction of polarized light to be irradiated.

The thickness of the photo-alignment film is usually 10 to 10,000 nm, preferably 10 to 1,000 nm, and more preferably 10 to 500 nm. When the thickness of the photo-alignment film is within the above range, the orientation regulating force is sufficiently exhibited.

(Polarizing coating layer forming composition)

The polarizing coating layer may be formed by applying the polarizing coating layer forming composition. Specifically, the polarizing coating layer-forming composition is a composition (hereinafter, referred to as composition B) containing a dichroic dye and one or more polymerizable liquid crystals (hereinafter sometimes referred to as polymerizable liquid crystals (B)) to be a host compound. It may be called).

The term "bichromatic dye" means a dye having different properties of absorbance in the long axis direction of the molecule and absorbance in the minor axis direction. If it has such properties, the dichroic dye is not limited, and may be a dye or a pigment. Two or more types of dyes may be used in combination, two or more types of pigments may be used in combination, and a dye and a pigment may be used in combination.

It is preferable that the dichroic dye has a maximum absorption wavelength (λ _MAX ) in a range of 300 to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes and anthraquinone dyes, and azo dyes are particularly preferred. Examples of the azo pigment include monoazo pigment, biszo pigment, triszo pigment, tetrakiszo pigment and stilbenazo pigment, and biszo pigment and triszo pigment are preferred.

The liquid crystal state represented by the polymerizable liquid crystal (B) is preferably a smectic phase, and more preferably a higher order smectic phase from the viewpoint of producing a polarizing layer having a higher degree of alignment. The polymerizable liquid crystal (B) showing a smectic phase is referred to as a polymerizable smectic liquid crystal compound. The polymerizable liquid crystal (B) can be used alone or in combination. Moreover, when combining 2 or more types of polymerizable liquid crystals, at least 1 type is preferable if it is a polymerizable liquid crystal (B), and 2 or more types are more preferable if it is a polymerizable liquid crystal (B). By combining, liquid crystallinity may be temporarily retained even at a temperature below the liquid crystal-crystal phase transition temperature. The polymerizable liquid crystal (B) is, for example, Lub et al. Recl. Trav. Chim. It is produced by a known method described in Pays-Bas, 115, 321-328 (1996), or Japanese Patent Publication No. 4719156. The content of the dichroic dye in the composition B can be appropriately adjusted depending on the type of the dichroic dye or the like, but is preferably 0.1 part by mass or more and 50 parts by mass or less, more preferably 100 parts by mass of the polymerizable liquid crystal (B). Is 0.1 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 10 parts by mass or less. When the content of the dichroic dye is within the above range, the orientation of the polymerizable liquid crystal (B) can be polymerized without disturbing, and the tendency to inhibit the orientation of the polymerizable liquid crystal (B) is small.

It is preferable that the composition B contains a solvent. In general, since the smectic liquid crystal compound has a high viscosity, a composition containing a solvent is easy to apply, and as a result, a polarizing film is often easily formed. As a solvent, the thing similar to the solvent contained in the oriented polymer composition mentioned above can be mentioned, and it can select suitably according to the solubility of a polymerizable liquid crystal (B) and a dichroic dye. The content of the solvent is preferably 50 to 98% by mass relative to the total amount of the composition B. In other words, the solid content in composition B is preferably 2 to 50% by mass.

It is preferable that the composition B contains one or more leveling agents. The leveling agent has a function of adjusting the fluidity of the composition B and making the coating film obtained by applying the composition B flatter, and specifically, a surfactant. When the composition B contains a leveling agent, the content is preferably 0.05 parts by mass or more and 5 parts by mass or less, more preferably 0.05 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the polymerizable liquid crystal. When the content of the leveling agent is within the above range, it is easy to horizontally align the polymerizable liquid crystal, and the resulting polarizing layer tends to be smoother. When the content of the leveling agent for the polymerizable liquid crystal is within the above-mentioned range, there is a tendency that variations do not occur much in the obtained polarizing layer.

It is preferable that the composition B contains one or more polymerization initiators. The polymerization initiator is a compound capable of initiating the polymerization reaction of the polymerizable liquid crystal (B), and a photopolymerization initiator is preferable because it can initiate the polymerization reaction under lower temperature conditions. Specifically, a photopolymerization initiator capable of generating an active radical or an acid by the action of light is mentioned, and among them, a photopolymerization initiator that generates a radical by the action of light is preferable. Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts and sulfonium salts.

When the composition B contains a polymerization initiator, the content can be appropriately adjusted depending on the type and amount of the polymerizable liquid crystal contained in the composition, but is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal. , More preferably, it is 0.5 to 10 parts by mass, and more preferably 0.5 to 8 parts by mass. When the content of the polymerization initiator is within this range, the orientation of the polymerizable liquid crystal (B) can be polymerized without disturbing. When composition B contains a photoinitiator, the composition may further contain a photosensitizer. When the composition B contains a photopolymerization initiator and a photosensitizer, the polymerization reaction of the polymerizable liquid crystal contained in the composition can be further promoted. The amount of the photosensitizer can be appropriately adjusted depending on the type and amount of the photopolymerization initiator and the polymerizable liquid crystal, but is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal. Parts, more preferably 0.5 to 8 parts by mass.

In order to advance the polymerization reaction of the polymerizable liquid crystal more stably, the composition B may contain an appropriate amount of a polymerization inhibitor, thereby making it easy to control the progress of the polymerization reaction of the polymerizable liquid crystal. When the composition B contains a polymerization inhibitor, the content can be appropriately adjusted depending on the type and amount of the polymerizable liquid crystal, and the amount of the photosensitizer, and the like, preferably 0.1 parts by mass based on 100 parts by mass of the polymerizable liquid crystal It is -30 mass parts, More preferably, it is 0.5-10 mass parts, More preferably, it is 0.5-8 mass parts. When the content of the polymerization inhibitor is within this range, polymerization can be performed without disturbing the alignment of the polymerizable liquid crystal.

(Production method of polarizing coating layer)

The polarizing coating layer is usually formed by applying a polarizing coating layer forming composition on a substrate subjected to an alignment treatment, and polymerizing the polymerizable liquid crystal in the obtained coating film. The method of applying the polarizing coating layer forming composition is not limited. Examples of the orientation treatment include those exemplified above. A dry coating is formed by applying the polarizing coating layer forming composition and drying the solvent under conditions in which the polymerizable liquid crystal contained in the obtained coating film does not polymerize. As a drying method, a natural drying method, a ventilation drying method, a heating drying, and a vacuum drying method are mentioned. When the polymerizable liquid crystal is a polymerizable smectic liquid crystal compound, it is preferable to set the liquid crystal state of the polymerizable smectic liquid crystal compound contained in the dry film to a nematic phase (nematic liquid crystal state) and then transition to the smectic phase. In order to form the smectic phase via the nematic phase, for example, the dry film is heated to a temperature higher than the temperature at which the polymerizable smectic liquid crystal compound contained in the dry film phase-transfers to the nematic phase liquid crystal state, and then, A method in which the meticic liquid crystal compound is cooled to a temperature indicating a liquid crystal state of the smectic phase is adopted. Next, a method of photopolymerizing the polymerizable liquid crystal while maintaining the liquid crystal state of the smectic phase after setting the liquid crystal state of the polymerizable liquid crystal in the dry film to the smectic phase will be described. In the photopolymerization, light to be irradiated on the dry film can be appropriately selected depending on the type of the photopolymerization initiator contained in the dry film, the type of the polymerizable liquid crystal (especially, the type of the photopolymerizable group of the polymerizable liquid crystal) and the amount thereof. , Specific examples thereof include active energy rays selected from the group consisting of visible light, ultraviolet light, and laser light. Of these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and one that is widely used in the art can be used as a photopolymerization device. By performing photopolymerization, the polymerizable liquid crystal is polymerized while maintaining the liquid crystal state of the smectic phase, preferably a higher order smectic phase, to form a polarizing layer.

(Phase difference coating layer)

In one embodiment of the present invention, the polarizing plate may include a retardation coating layer. The retardation coating layer generally refers to a λ / 2 layer, a λ / 4 layer, a positive C layer, etc. according to optical properties. The retardation coating layer is, for example, by applying a coating layer forming composition containing a liquid crystal compound on a substrate film subjected to alignment treatment to form a liquid crystal coating layer, and then attaching the liquid crystal coating layer to the polarizing plate via an adhesive layer, and then attaching the base film. Although it can form by peeling, it is not limited to this method. As the base film, a polymer film exemplified as a protective film can be used, and surface treatment may be performed on the base material surface on the side where the alignment film and the retardation layer are formed before forming the alignment film. Since the alignment film forming composition and its coating and drying method are the same as those described for the polarizing coating layer, the description is omitted to avoid overlap. The composition of the coating layer forming composition is the same as that described for the polarizing coating layer, except that it does not contain a dichroic dye. In addition, since the coating, drying, and curing methods of the coating layer forming composition are the same as those described in the polarizing coating layer, the description is omitted to avoid overlap.

The thickness of the retardation coating layer is usually 0.5 to 10 μm, preferably 1 to 4 μm.

In one embodiment of the present invention, the retardation coating layer can adjust optical properties according to the thickness of the coating layer, the alignment state of the polymerizable liquid crystal compound, and the like. Specifically, by adjusting the thickness of the retardation coating layer, a retardation coating layer that provides a desired in-plane retardation can be produced. The in-plane retardation value (in-plane retardation value, Re) is a value defined by Equation (1), and to obtain the desired Re, Δn and the film thickness (d) may be adjusted.

Re = d × Δn (λ)… Equation (1) (here Δn = nx-ny)

(In the formula (1), Re represents the in-plane retardation value, d represents the thickness of the retardation coating layer, and Δn represents the birefringence. When a refractive index ellipsoid formed according to the orientation of the polymerizable liquid crystal compound is considered, three directions The refractive indices, i.e., nx, ny, and nz are defined as follows: nx represents the main refractive index in a direction parallel to the substrate plane in the refractive index ellipsoid formed by the retardation layer, where ny is the refractive index formed by the retardation layer Refractive index in a direction perpendicular to the plane of the substrate in the ellipsoid and parallel to the direction of nx Refractive index formed by the retardation layer Refractive index in the direction perpendicular to the substrate plane in the ellipsoid Retardation layer In the case of this λ / 4 layer, the in-plane retardation value Re (550) is usually in the range of 113 to 163nm, preferably in the range of 130 to 150nm.When the retardation layer is λ / 2 layer, Re (550) is The organization is in the range of 250 ~ 300nm.)

Moreover, according to the alignment state of a polymerizable liquid crystal compound, a retardation layer which expresses a retardation in the thickness direction can be produced. The expression of the retardation in the thickness direction indicates the characteristic that the retardation value Rth in the thickness direction becomes negative in Equation (2).

Rth = [(nx + ny) / 2-nz] × d… Equation (2)

(In Formula (2), nx, ny, nz, and d are as defined above.)

The in-plane retardation value Re (550) of the positive C layer is usually in the range of 0 to 10 nm, preferably in the range of 0 to 5 nm, and the retardation value Rth in the thickness direction is usually in the range of -10 to -300 nm, preferably -20 It is in the range of ~ -200nm. The polarizing plate of the present invention may have two or more retardation coating layers, and when the retardation coating layer has two layers, the first retardation coating layer is a λ / 4 layer for making circularly polarized light, and the second retardation coating layer is obliquely colored It may be a positive C layer to improve the. Further, the first retardation coating layer is a positive C layer for improving the color sense seen obliquely, and the second retardation coating layer may be a λ / 4 layer for making circularly polarized light.

(Adhesive or adhesive)

In one embodiment of the present invention, the polarization coating layer and the first retardation coating layer, or the first retardation coating layer and the second retardation coating layer may be pasted through an adhesive or an adhesive. As the adhesive for forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and is preferably a water-based adhesive or an active energy ray-curable adhesive. What is mentioned later can be used as an adhesive layer.

Examples of the water-based adhesive include an adhesive composed of an aqueous polyvinyl alcohol-based resin, an aqueous two-component urethane emulsion adhesive, and the like. Among them, an aqueous adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin is suitably used. As the polyvinyl alcohol-based resin, in addition to the vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, a polyvinyl alcohol-based copolymer obtained by saponifying a copolymer of vinyl acetate and other monomers copolymerizable therewith Copolymers or modified polyvinyl alcohol-based polymers partially modified with their hydroxyl groups can be used. The water-based adhesive may contain a crosslinking agent such as an aldehyde compound (glyoxal, etc.), an epoxy compound, a melamine-based compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

In the case of using an aqueous adhesive, it is preferable to perform a drying process for removing water contained in the aqueous adhesive after bonding the coating layer.

The active energy ray-curable adhesive is an adhesive containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet curable adhesive.

The curable compound may be a cationic polymerizable curable compound or a radical polymerizable curable compound. As a cationically polymerizable curable compound, for example, an epoxy-based compound (a compound having one or two or more epoxy groups in a molecule) or an oxetane-based compound (a compound having one or two or more oxetane rings in a molecule), Or a combination of these. Examples of the radically polymerizable curable compound include (meth) acrylic compounds (compounds having one or two or more (meth) acryloyl oxy groups in the molecule) or other vinyl-based compounds having a radically polymerizable double bond, Or a combination of these. You may use together a cationically polymerizable curable compound and a radically polymerizable curable compound. The active energy ray-curable adhesive usually further comprises a cationic polymerization initiator and / or a radical polymerization initiator for initiating a curing reaction of the curable compound.

When bonding a coating layer, in order to improve adhesiveness, surface activation treatment may be performed on at least one of the bonding surfaces of the bonding surfaces. Examples of the surface activation treatment include dry treatment such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, and ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.); And wet treatment such as ultrasonic treatment using a solvent such as water or acetone, saponification treatment, and anchor coating treatment. The surface activation treatment may be performed alone or in combination of two or more.

The thickness of the adhesive layer can be adjusted according to the adhesive strength, preferably 0.1 to 10 μm, more preferably 1 to 5 μm. In one embodiment of the present invention, in the case where a plurality of the adhesive layers are used, they may be made of the same material or different materials, and may have the same thickness or different thickness.

The pressure-sensitive adhesive layer can be composed of a pressure-sensitive adhesive composition mainly composed of resins such as (meth) acrylic resin, rubber-based resin, polyurethane-based resin, polyester-based resin, silicone-based resin, and polyvinyl ether-based resin. Especially, the adhesive composition which consists of a polyester resin or (meth) acrylic resin excellent in transparency, weather resistance, heat resistance, etc. as a base polymer is preferable. The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type.

As the pressure-sensitive adhesive resin used in the present invention, those having a weight average molecular weight in the range of 300,000 to 4,000,000 are usually used. When considering durability, especially heat resistance, the weight average molecular weight is preferably 500,000 to 3,000,000, more preferably 650,000 to 2,000,000. If the weight average molecular weight is larger than 300,000, it is preferable from the viewpoint of heat resistance, and if the weight average molecular weight is smaller than 4,000,000, it is also preferable from the point of stickiness and adhesion deterioration. In addition, the weight average molecular weight refers to the value calculated by polystyrene conversion, measured by GPC (gel-phase chromatography).

Additionally, the pressure-sensitive adhesive composition may contain a crosslinking agent. As the crosslinking agent, an organic crosslinking agent or a polyfunctional metal chelate can be used. As an organic type crosslinking agent, an isocyanate type crosslinking agent, peroxide type crosslinking agent, epoxy type crosslinking agent, imine type crosslinking agent, etc. are mentioned. The polyfunctional metal chelate is one in which the polyvalent metal is covalently or coordinated with an organic compound. Examples of the polyvalent metal atom include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. have. Examples of the atoms in the covalent or coordinating organic compound include an oxygen atom, and examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

When a crosslinking agent is contained, the amount used is preferably 0.01 to 20 parts by mass, more preferably 0.03 to 10 parts by mass, relative to 100 parts by mass of the pressure-sensitive adhesive resin. In addition, when the crosslinking agent exceeds 0.01 parts by mass, there is a tendency that the cohesive force of the pressure-sensitive adhesive layer is not insufficient, so there is less possibility of foaming during heating, while when it is less than 20 parts by mass, moisture resistance is sufficient, and peeling occurs in reliability tests, etc It becomes difficult to occur.

It is preferable to blend a silane coupling agent as an additive. Examples of the silane coupling agent include silicon having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyl trimethoxysilane. compound; Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, and N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane; 3-chloropropyl trimethoxysilane; (Meth) acryl group-containing silane coupling agents, such as acetoacetyl group-containing trimethoxysilane, 3-acryloxypropyl trimethoxysilane, and 3-methacryloxypropyl triethoxysilane; And isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane. The silane coupling agent can impart durability, particularly an effect of suppressing peeling under a humid environment. The amount of the silane coupling agent used is preferably 1 part by mass or less, more preferably 0.01 to 1 part by mass, and even more preferably 0.02 to 0.6 part by mass relative to 100 parts by mass of the pressure-sensitive adhesive resin.

Further, the pressure-sensitive adhesive composition may contain other known additives. For example, in the pressure-sensitive adhesive composition, powders such as colorants and pigments, dyes, surfactants, plasticizers, tackifiers, and surface lubricants , Leveling agent, softening agent, antioxidant, anti-aging agent, light stabilizer, ultraviolet absorber, polymerization inhibitor, inorganic or organic filler, metal powder, particulate, thin material, etc., can be appropriately added depending on the intended use. You can. Moreover, a redox system to which a reducing agent is added may be employed within a controllable range.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, preferably 2 to 50 μm, and more preferably 3 to 30 μm. By reducing the thickness of the pressure-sensitive adhesive layer, the total amount of acid in the pressure-sensitive adhesive layer is lowered. This makes it difficult for the acid component to corrode the wiring of the substrate. Moreover, the adhesive layer which a 2nd layer has can be adjusted according to the thickness of the flexible printed circuit board to which it fits.

(Protective layer)

In one embodiment of the present invention, the polarizing plate may have a form having at least one or more protective layers, and one surface of the polarizer constituting the polarizing plate, or when the polarizer has a retardation layer, the surface opposite to the polarizer of the retardation layer Can be located at

The protective layer is not particularly limited as long as it is a film excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, isotropy, and the like. Specifically, polyester-based films such as polyethylene terephthalate, polyethylene isophthalate, and polybutylene terephthalate; Cellulose-based films such as diacetyl cellulose and triacetyl cellulose; Polycarbonate-based films; Acrylic films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene-based films such as polystyrene and acrylonitrile-styrene copolymers; Polyolefin-based films such as cycloolefin, cycloolefin copolymer, polynorbornene, polypropylene, polyethylene, and ethylene propylene copolymer; Vinyl chloride film; Polyamide-based films such as nylon and aromatic polyamide; Imide-based film; Sulfone-based films; Polyether ketone-based films; Polyphenylene sulfide-based films; Vinyl alcohol-based films; Vinylidene chloride-based films; Vinyl butyral-based film; Arylate-based film; Polyoxymethylene-based films; Urethane-based films; Epoxy film; And silicone-based films. Among these, a cellulose-based film having a surface saponified with an alkali or the like is preferable in consideration of polarization properties or durability. Moreover, the protective layer may have an optical compensation function such as a phase difference function.

The protective layer may be subjected to an easy-adhesive treatment for improving adhesion to the surface to be adhered to the polarizer or the retardation coating layer. The adhesion treatment is not particularly limited as long as it can improve the adhesion, and includes, for example, dry treatment such as primer treatment, plasma treatment, and corona treatment; Chemical treatment such as alkali treatment (saponification treatment); And low pressure UV treatment.

(Touch sensor)

The touch sensor has a base material, a lower electrode provided on the base material, an upper electrode facing the lower electrode, and an insulating layer sandwiched between the lower electrode and the upper electrode.

As the base material, various materials can be employed as long as they are flexible resin films having light transmission properties. For example, as a base material, the film illustrated as the material of the above-mentioned transparent base material can be used.

The lower electrode has, for example, a plurality of small electrodes having a square shape in plan view. The plurality of small electrodes are arranged in a matrix shape.

Further, the plurality of small electrodes are connected to each other of the small electrodes adjacent to each other in the diagonal direction to form a plurality of electrode rows. The plurality of electrode rows are connected to each other at the ends, so that the capacitance between adjacent electrode rows can be detected.

The upper electrode has, for example, a plurality of small electrodes having a square shape in plan view. The plurality of small electrodes are arranged in a complementary matrix shape at a position where the lower electrode is not disposed in plan view. That is, the upper electrode and the lower electrode are disposed without a gap in plan view.

In addition, a plurality of small electrodes are connected to each other in the diagonal direction of the other side of the small electrodes, thereby forming a plurality of electrode rows. The plurality of electrode rows are connected to each other at the ends, so that the capacitance between adjacent electrode rows can be detected.

The insulating layer insulates the lower electrode and the upper electrode. As the material for forming the insulating layer, a material commonly known as the material for the insulating layer of the touch sensor can be used.

Further, in the present embodiment, the touch sensor has been described as being a so-called projection-type capacitive touch sensor, but to the extent that the effects of the invention are not impaired, other types of touch sensors such as a film resistance method are employed. It might be.

(Shading pattern)

The light blocking pattern may be provided as a window film or at least a part of a bezel or housing of a display device to which the window film is applied. For example, each wiring of the display device may be obscured by the light-shielding pattern, and the user may not see it. The color and / or material of the light blocking pattern is not particularly limited, and may be formed of a resin material having various colors such as black, white, and gold. For example, the light-shielding pattern may be formed of a resin material such as an acrylic resin, an ester resin, an epoxy resin, a polyurethane, and a silicone in which pigments for realizing color are mixed. The material and thickness of the light blocking pattern may be determined in consideration of the protective and flexible properties of the window film or display device. Moreover, these can also be used individually or in mixture of 2 or more types.

Example

Hereinafter, the present invention will be described in more detail by examples. In the examples, "%" and "parts" mean mass% and parts by mass unless otherwise specified. First, the evaluation method will be described.

<Measurement of weight average molecular weight (Mw)>

Gel permeation chromatography (GPC) measurements

(1) Pretreatment method

A DMF eluent (10 mmol / L lithium bromide solution) of the polyamideimide resin obtained in Examples and Comparative Examples was added to a concentration of 2 mg / mL, heated with stirring at 80 ° C. for 30 minutes, and after cooling, a 0.45 μm membrane filter What was filtered was used as the measurement solution.

(2) Measurement conditions

Column: TSKgel α-2500 ((7) 7.8 mm diameter × 300 mm) × 1, α-M ((13) 7.8 mm diameter × 300 mm) × 2 manufactured by TOSOH CORPORATION

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

Flow rate: 1.0 mL / min

Detector: RI detector

Column temperature: 40 ° C

Injection volume: 100 μL

Molecular weight standard: standard polystyrene

<Measurement of thickness>

The thickness of the optical film obtained in Examples and Comparative Examples was measured using a micrometer ("ID-C112XBS" manufactured by Mitutoyo Corporation).

<Measurement of light transmittance>

The transmittance to light of 300-800 nm of the optical films obtained in Examples and Comparative Examples was measured using an ultraviolet visible near-infrared spectrophotometer V-670 manufactured by JASCO Corporation. From the measurement results, light transmittance at 375 nm and 420 nm was read.

<Measurement of yellowness (YI)>

The yellowness index (Yellow Index: YI) of the optical films obtained in Examples and Comparative Examples was measured using an ultraviolet visible near-infrared spectrophotometer V-670 manufactured by Japan Spectrum Co., Ltd. according to JIS K 7373: 2006. . After the background was measured in the absence of a film, the film was set in a sample holder, and the transmittance of 300-800 nm was measured for light to obtain tristimulus values (X, Y, Z). YI was calculated based on the following formula.

YI = 100 × (1.2769X-1.0592Z) / Y

<Measurement of ΔYI>

The following light resistance test was performed on the optical films obtained in Examples and Comparative Examples, and the amount of change in YI before and after the light resistance test was calculated as ΔYI.

(Light resistance test)

Using UVCON (lamp: UVB 313 nm) manufactured by Atlas, light was irradiated to the surface not contacting the support (substrate) during film formation of the optical film, and the film was irradiated for 24 hours.

The smaller the ΔYI value, the smaller the amount of change in the yellowness (YI) before and after the light resistance test, indicating that the light resistance is high.

<Example 1>

[Preparation of polyamideimide resin (1)]

In a 1 L separable flask with a stirring vane under a nitrogen atmosphere, 14.20 g (44.34 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB) and 250.00 g of N, N-dimethylacetamide (DMAc) It was added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 7.96 g (18.00 mmol) of 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. Thereafter, 5.62 g (26.88 mmol) of 2,5-thiophenedicarboxylic acid chloride (TDOC) was added to the flask and stirred at room temperature for 1 hour. Subsequently, 2.50 g (26.84 mmol) of 4-picoline and 12.80 g (125.38 mmol) of acetic anhydride were added to the flask, stirred at room temperature for 30 minutes, heated to 70 ° C using an oil bath, and further 3 hours. The mixture was stirred to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, charged into a large amount of methanol in a thread form, and the precipitated precipitate was taken out and immersed in methanol for 6 hours, followed by washing with methanol. Next, the precipitate was dried under reduced pressure at 60 ° C to obtain a polyamideimide resin (1). The weight average molecular weight (Mw) of the polyamideimide resin (1) was 740,000.

[Production of Optical Film 1]

DMAc was added to the obtained polyamideimide resin (1) so that the concentration was 10% by mass, thereby producing a polyamideimide varnish (1). The obtained polyamideimide varnish (1) was coated on a smooth surface of a polyester substrate (manufactured by TOYOBO CO., LTD., Trade name "A4100") using an applicator so that the thickness of the freestanding film was 50 μm. It was dried for 30 minutes at 50 ° C and then at 140 ° C for 15 minutes to obtain a freestanding film. The freestanding film was fixed to the metal frame, and further dried at 200 ° C. for 60 minutes to obtain an optical film 1 having a thickness of 45 μm. When the light transmittance and ΔYI of the optical film 1 were measured by the above measuring method, the light transmittance of 375 nm was 0%, the light transmittance of 420 nm was 85%, and ΔYI was 0.7.

<Comparative Example 1>

[Preparation of polyamideimide resin (2)]

14.29 g (44.62 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB) and 250 g of N, N-dimethylacetamide (DMAc) were added to a 1 L separable flask with a stirring blade under a nitrogen atmosphere. And TFMB was dissolved in DMAc while stirring at room temperature. Next, 8.01 g (18.11 mol) of 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. Thereafter, 5.49 g (27.04 mmol) of terephthaloyl dichloride (TPC) was added to the flask and stirred at room temperature for 1 hour. Subsequently, 2.52 g (27.06 mmol) of 4-picoline and 12.88 g (126.16 mmol) of acetic anhydride were added to the flask, stirred at room temperature for 30 minutes, heated to 70 ° C using an oil bath, and additionally 3 hours. The mixture was stirred to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a solid form, and the precipitated precipitate was taken out and immersed in methanol for 6 hours, followed by washing with methanol. Next, the precipitate was dried under reduced pressure at 60 ° C to obtain a polyamideimide resin (2). The weight average molecular weight (Mw) of the polyamideimide resin (2) was 290,000.

[Production of Optical Film 2]

DMAc was added to the obtained polyamideimide resin (2) so that the concentration became 10% by mass, thereby producing a polyamideimide varnish (2). The obtained polyamideimide varnish (2) was coated on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the thickness of the freestanding film was 55 µm, and at 50 ° C for 30 minutes, Then, drying was performed at 140 ° C for 15 minutes to obtain a freestanding film. The freestanding film was fixed to a metal frame, and further dried at 200 ° C. for 60 minutes to obtain an optical film 2 having a thickness of 50 μm. When the light transmittance and ΔYI of the optical film 2 were measured by the above measuring method, the light transmittance of 375 nm was 25%, the light transmittance of 420 nm was 87%, and ΔYI was 3.0.

<Example 2>

[Preparation of polyamideimide resin (3)]

In a 1L separable flask with a stirring vane under a nitrogen atmosphere, 2,2'-bis (trifluoromethyl) benzidine (TFMB) 16.56 g (51.70 mmol) and N, N-dimethylacetamide (DMAc) 313.57 g It was added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 13.92 g (31.33 mmol) of 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. Thereafter, 4.37 g (20.89 mmol) of 2,5-thiophenedicarboxylic acid chloride (TDOC) was added to the flask and stirred at room temperature for 1 hour. Subsequently, 1.95 g (20.89 mmol) of 4-picoline and 22.39 g (219.34 mmol) of acetic anhydride were added to the flask, stirred at room temperature for 30 minutes, heated to 70 ° C using an oil bath, and additionally 3 hours. The mixture was stirred to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a solid form, and the precipitated precipitate was taken out and immersed in methanol for 6 hours, followed by washing with methanol. Next, the precipitate was dried under reduced pressure at 60 ° C to obtain a polyamideimide resin (3). The weight average molecular weight (Mw) of the polyamideimide resin (3) was 298,000.

[Production of Optical Film 3]

DMAc was added to the obtained polyamideimide resin (3) so that the concentration was 10% by mass, thereby producing a polyamideimide varnish (3). The obtained polyamide-imide varnish (3) was coated on a smooth surface of a polyester substrate (manufactured by TOYOBO Corporation, trade name "A4100") using an applicator so that the thickness of the freestanding film was 50 µm, and at 50 ° C for 30 minutes, Then, drying was performed at 140 ° C for 15 minutes to obtain a freestanding film. The freestanding film was fixed to a metal frame and further dried at 200 ° C. for 60 minutes to obtain an optical film 3 having a thickness of 50 μm. When the light transmittance and ΔYI of the optical film 3 were measured by the above measuring method, the light transmittance of 375 nm was 1%, the light transmittance of 420 nm was 87%, and ΔYI was 0.7.

<Example 3>

[Preparation of polyamideimide resin (4)]

In a 1L separable flask with a stirring vane under a nitrogen atmosphere, 2,2'-bis (trifluoromethyl) benzidine (TFMB) 19.19 g (59.91 mmol) and N, N-dimethylacetamide (DMAc) 313.57 g It was added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 5.43 g (12.23 mmol) of 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. Then, 10.22 g (48.91 mmol) of 2,5-thiophenedicarboxylic acid chloride (TDOC) was added to the flask and stirred at room temperature for 1 hour. Subsequently, 4.56 g (48.91 mmol) of 4-picoline and 8.74 g (85.59 mmol) of acetic anhydride were added to the flask, stirred at room temperature for 30 minutes, heated to 70 ° C using an oil bath, and additionally 3 hours. The mixture was stirred to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a solid form, and the precipitated precipitate was taken out and immersed in methanol for 6 hours, followed by washing with methanol. Next, the precipitate was dried under reduced pressure at 60 ° C to obtain a polyamideimide resin (4). The weight average molecular weight (Mw) of the polyamideimide resin (4) was 283,000.

[Production of Optical Film 4]

DMAc was added to the obtained polyamideimide resin (4) so that the concentration was 10% by mass, thereby producing a polyamideimide varnish (4). The obtained polyamide-imide varnish (4) was coated on a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the thickness of the freestanding film was 50 µm, followed by 30 minutes at 50 ° C. It dried at 140 degreeC for 15 minutes, and the freestanding film was obtained. The freestanding film was fixed to a metal frame, and further dried at 200 ° C. for 60 minutes to obtain an optical film 4 having a thickness of 50 μm. When the light transmittance and ΔYI of the optical film 4 were measured by the above measuring method, the light transmittance of 375 nm was 0%, the light transmittance of 420 nm was 84%, and ΔYI was 0.7.

Table 1 shows the structural units of the polyamideimide resin, the light transmittance at 375 nm and 420 nm of the optical film, and ΔYI. In addition, among the structural units, the number in parentheses indicates the ratio (content) of each structural unit, for example, in Example 1, TDOC unit: 6FDA unit: TFMB unit = 60:40: 100.

As shown in Table 1, it was confirmed that the optical films obtained in Examples 1 to 3 had a significantly smaller ΔYI and better light resistance than the optical films obtained in Comparative Example 1.

Claims (6)

Equations (1) and (2b)

[In formula (1) and formula (2b), X and L each independently represent a divalent organic group, and Y represents a tetravalent organic group]
The polyamide-imide resin containing the structural unit represented by,
The optical film whose light transmittance at wavelength 420 nm is 70% or more, and the light transmittance at wavelength 375 nm is 5% or less. According to claim 1,
The optical film whose content of the ultraviolet absorber in an optical film is less than 1 mass part with respect to 100 mass parts of polyamideimide resin. According to claim 1,
In the formula (2b), L is a divalent heterocyclic ring. A flexible display device comprising the optical film according to claim 1. According to claim 4,
A flexible display device further comprising a touch sensor. According to claim 4,
A flexible display device further comprising a polarizing plate.