KR20200077493A - Optical film - Google Patents

Abstract

Provided is an optical film which has excellent flexibility resistance and exhibits stable optical characteristics in high-temperature and high-humidity conditions. The optical film of the present invention comprises a polyamide-imide resin and satisfies the relation represented by formula (1). ΔHz < 0.5 (1) [In the formula (1), ΔHz denotes Hz_a - Hz_b, wherein Hz_a represents a haze (%) of the optical film following the Mendrel test (based on JIS K 5600-5-1 : 1999) in which the optical film is bent once by a bending radius of 1 mm before returning to a flat shape at room temperature, and Hz_b represents a haze (%) of the optical film prior to the aforesaid Mandrel test.

Description

Optical film {OPTICAL FILM}

It relates to an optical film used as a material for a flexible display.

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. Although glass has been used as the front plate of such an image display device, it is difficult to use the flexible display as a front plate material because it is very rigid and fragile. As one of the materials to replace glass, there is a polyamideimide resin, and a polyamideimide film having high heat resistance and the like using the polyamideimide resin has been studied (for example, Patent Document 1).

Japanese Patent Publication No. 2014-528490

However, according to the examination of the present inventors, it has been found that, in order to use such a polyamideimide film (optical film) as a flexible display material, there are cases where the bending resistance and the stability of optical properties under high temperature and high humidity may not be sufficient.

Accordingly, an object of the present invention is to provide an optical film having excellent bending resistance and excellent stability of optical properties under high temperature and high humidity.

As a result of earnest examination to solve the above problems, the present inventors have accomplished the present invention. That is, the following suitable aspects are included in this invention.

[1] An optical film comprising a polyamideimide resin,

Equation (1)

ΔHz<0.5 (One)

[In formula (1), ΔHz denotes Hz _a -Hz _b , and Hz _a is a mandrel test that returns to a flat shape by bending once with a bending radius of 1 mm at room temperature (JIS K 5600-5-1:1999). Conformity) represents the haze (%) of the optical film after, Hz _b represents the haze (%) of the optical film before the mandrel test]

Optical film, meeting the relationship of.

[2] The polyamideimide resin is a resin containing a structural unit derived from a dicarboxylic acid compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a diamine compound, and further has an average primary particle size of 100 nm or less. The optical film according to [1], comprising silica particles.

[3] The optical film according to [2], wherein the average primary particle size of the silica particles is 80 nm or less.

[4] The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin is represented by formula (I)

[Formula 1]

[In formula (I), R ¹ and R ² each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ³ to R ⁶ are each Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ³ to R ⁶ may be each independently substituted with a halogen atom]

Containing a structural unit derived from the compound represented by,

Equation (2)

0<R _Si ≤32+2/3×R _(I) (2)

[In formula (2), R _Si represents the content (mass %) of silica particles with respect to the mass of the optical film, and R _(I) represents the formula (I) with respect to the total number of moles of all constituent units constituting the polyamideimide resin. ) Represents the content (mol%) of the structural unit derived from the compound]

The optical film according to [2] or [3], which satisfies the relationship of

[5] The optical film according to [4], wherein the formula (2) is 5≤R _Si ≤50.

[6] The structural unit derived from the tetracarboxylic acid compound constituting the polyamideimide resin is represented by formula (II)

[Formula 2]

[In the formula (II), R ⁷ to R ¹⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ⁷ to R ¹⁴ are each independently May be substituted with a halogen atom]

The structural unit derived from the diamine compound which comprises the structural unit derived from the compound represented by and which comprises the said polyamideimide resin is Formula (III).

[Formula 3]

[In formula (III), R ¹⁵ to R ²² each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹⁵ to R ²² are each Independently, it may be substituted with a halogen atom]

The optical film as described in any one of [2] to [5], which includes a structural unit derived from a compound represented by.

[7] The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin is represented by formula (IV)

[Formula 4]

[In formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ²⁵ to R ³² are , Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ²⁵ to R ³² may be each independently substituted with a halogen atom, and A is Each independently, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -NR ³³ -, R ³³ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and m represents an integer of 1 to 4]

The optical film according to any one of [2] to [6], which includes a structural unit derived from a compound represented by a compound.

The optical film of the present invention has excellent bending resistance and excellent stability of optical properties under high temperature and high humidity.

The optical film of the present invention comprises a polyamideimide resin.

<Polyamideimide resin>

In this specification, the polyamideimide resin refers to a polymer containing both a repeating structural unit containing an imide group and a repeating structural unit containing an amide group. It is preferable that the polyamideimide resin is a resin in which a dicarboxylic acid compound, a tetracarboxylic acid compound, and a carboxylic acid compound containing a tricarboxylic acid compound and a diamine compound are copolymerized as necessary. Therefore, the polyamideimide resin of the present invention is derived from a carboxylic acid compound containing a structural unit derived from a dicarboxylic acid compound, a structural unit derived from a tetracarboxylic acid compound, and, if necessary, a structural unit derived from a tricarboxylic acid compound. The structural unit and the structural unit derived from a diamine compound are included. In addition, in this specification, "a structural unit derived from a compound" may be referred to simply as a "unit." For example, the dicarboxylic acid "constituent unit derived from a compound" is referred to as a dicarboxylic acid "unit", the tetracarboxylic acid "constituent unit derived from a compound" is referred to as a tetracarboxylic acid "unit", and a diamine "constituent derived from a compound" There may be a case where a unit is referred to as a diamine “unit”.

The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin is represented by formula (I)

[Formula 5]

[In formula (I), R ¹ and R ² each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ³ to R ⁶ are each Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ³ to R ⁶ may be each independently substituted with a halogen atom]

It is preferable to include the structural unit derived from the compound represented by (it may be called a structural unit derived from the dicarboxylic acid compound (I)).

In addition, the structural unit derived from the tetracarboxylic acid compound constituting the polyamideimide resin is represented by formula (II)

[Formula 6]

[In the formula (II), R ⁷ to R ¹⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ⁷ to R ¹⁴ are each independently May be substituted with a halogen atom]

It is preferable to include the structural unit derived from the compound represented by (which may be referred to as a structural unit derived from the tetracarboxylic acid compound (II)), and the structural unit derived from the diamine compound constituting the polyamideimide resin is represented by formula ( Ⅲ)

[Formula 7]

[In formula (III), R ¹⁵ to R ²² each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹⁵ to R ²² are each Independently, it may be substituted with a halogen atom]

It is preferable to contain the structural unit derived from the compound represented by (it may be called a structural unit derived from the diamine compound (III)). Here, in the polyamideimide resin, the structural unit derived from the dicarboxylic acid compound (I) is derived from the diamine compound via an amide group formed by reaction (polycondensation) of the dicarboxylic acid compound (I) and the diamine compound. Can be combined with the constituent units of. The structural unit derived from the tetracarboxylic acid compound (II) can be bonded to the structural unit derived from the diamine compound via an imide group formed by reaction (polycondensation) of the tetracarboxylic acid compound (II) with the diamine compound. . The structural unit derived from the diamine compound (III) is a dicarboxylic acid via an amide group or an imide group formed by reaction (polycondensation) of the diamine compound (III) with dicarboxylic acid, tricarboxylic acid or tetracarboxylic acid. It can combine with a structural unit derived from a compound, a structural unit derived from a tricarboxylic acid compound, or a structural unit derived from a tetracarboxylic acid compound.

Dicarboxylic acid units constituting the polyamideimide resin (preferably, structural units derived from dicarboxylic acid compound (I)), tetracarboxylic acid units (preferably, structural units derived from tetracarboxylic acid compound (II)) And the diamine unit (preferably, the structural unit derived from the diamine compound (III)) may each contain 1 type or 2 or more types.

In formula (I), R ¹ and R ² are each independently a hydroxyl group (-OH), methoxy group (-OMe), ethoxy group (-OEt), n-propoxy group (-OPr), n It is preferably a butoxy group (-OBu) or a chlorine atom (-Cl) and a chlorine atom (-Cl).

In Formula (I), R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl 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 aryl group having 6 to 12 carbon atoms include phenyl group, tril group, xylyl group, naphthyl group, and biphenyl group. The hydrogen atom contained in R ³ to R ⁶ may be each independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Moreover, as a C6-C12 aryl group substituted with a halogen atom, for example, a chlorophenyl group, dichlorophenyl group, bromophenyl group, dibromophenyl group, chlorobromophenyl group, chlorobiphenyl group, dichlorobiphenyl group, chloronaphthyl group , Dichloronaphthyl group, bromonaphthyl group, dibromonaphthyl group, and the like.

Among these, R ³ to R ⁶ are preferably each independently a hydrogen atom, a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group from the viewpoint of bending resistance of the optical film, and particularly preferably a hydrogen atom. Do. In addition, in this invention, bending resistance (flex resistance) shows the characteristic that it is hard to generate|occur|produce a wound, a crack, a cloudiness, etc. to an optical film, when repeated bending and returning of an optical film continuously.

In a more suitable embodiment of the present invention, the structural unit derived from the compound represented by formula (I) is represented by formula (I')

[Formula 8]

It is a structural unit derived from the compound represented by (it may be called a structural unit derived from the dicarboxylic acid compound (I')). When the polyamideimide resin contains a structural unit derived from the dicarboxylic acid compound (I'), it is easy to improve the mechanical strength of the optical film, for example, elastic modulus and flex resistance.

In the formula (II), R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 6 to 12 carbon atoms. Represents an aryl group. Examples of the alkyl group having 1 to 6 carbon atoms include those illustrated as R ³ to R 6 alkyl groups having 1 to ⁶ carbon atoms. Examples of the aryl group having a carbon number of 6 to 12, those exemplified as the aryl group having a carbon number of 6 to 12 of the R ³ ~R ^6. The hydrogen atom contained in R ⁷ to R ¹⁴ may be each independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Moreover, as a C6-C12 aryl group substituted by the halogen atom, what was illustrated as a C6-C12 aryl group substituted by the halogen atom of R<^3>-R<^6> is mentioned.

Among these, R ⁷ to R ¹⁴ are each independently a hydrogen atom, a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group from the viewpoint of easy to improve the bending resistance and transparency of the optical film, and more Preferably R ⁷ , R ⁸ , R ⁹ , R ¹² , R ¹³ and R ¹⁴ are hydrogen atoms, R ¹⁰ and R ¹¹ are hydrogen atoms, methyl groups, fluoro groups, chloro groups or trifluoromethyl groups, especially R It is preferred that ¹⁰ and R ¹¹ are methyl groups or trifluoromethyl groups.

In a preferred embodiment of the present invention, the structural unit derived from the compound represented by formula (II) is represented by formula (II')

[Formula 9]

It is a structural unit derived from the compound represented by (it may be called a structural unit derived from the tetracarboxylic acid compound (II')). When the polyamideimide resin contains a structural unit derived from the tetracarboxylic acid compound (II'), the bending resistance and transparency (for example, haze, total light transmittance) of the optical film can be improved. Moreover, the solubility of the polyamideimide resin in the solvent can be improved by the skeleton containing the fluorine element, the viscosity of the polyamideimide varnish can be suppressed to be low, and the production of the optical film becomes easy.

In formula (III), R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ and R ²² are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 6 to 12 carbon atoms. Represents an aryl group. Examples of the alkyl group having 1 to 6 carbon atoms include those illustrated as R ³ to R 6 alkyl groups having 1 to ⁶ carbon atoms. The aryl group of 6 to 12 carbon atoms, may be mentioned as examples of the aryl group having a carbon number of 6 to 12 of the R ³ ~R ^6. The hydrogen atom contained in R ¹⁵ to R ²² may be each independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Moreover, as a C6-C12 aryl group substituted by the halogen atom, what was illustrated as a C6-C12 aryl group substituted by the halogen atom of R<^3>-R<^6> is mentioned.

Among these, R ¹⁵ to R ²² are each independently a hydrogen atom, a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group from the viewpoint of easily improving the transparency of the optical film, and more preferably R ¹⁵ , R ¹⁷ , R ¹⁸ , R ¹⁹ , R ²⁰ and R ²² are hydrogen atoms, R ¹⁶ and R ²¹ are hydrogen atoms, methyl groups, fluoro groups, chloro groups or trifluoromethyl groups, especially R ¹⁶ and R It is preferable that ²¹ is a methyl group or a trifluoromethyl group.

In a preferred embodiment of the present invention, the structural unit derived from the compound represented by formula (III) is represented by formula (III')

[Formula 10]

It is a structural unit derived from the compound represented by (it may be called a structural unit derived from the diamine compound (III')). When the polyamideimide resin contains a structural unit derived from the diamine compound (III'), mechanical strength (for example, modulus of elasticity, flex resistance) and transparency of the optical film can be improved. Moreover, the solubility of the polyamideimide resin in the solvent can be improved by the skeleton containing the fluorine element, the viscosity of the polyamideimide varnish can be suppressed to be low, and the production of the optical film becomes easy.

The polyamideimide resin contained in the optical film of the present invention is a dicarboxylic acid unit from the viewpoint of easy to improve the bending resistance and transparency of the optical film, wherein two or more aromatic hydrocarbon rings are connected by divalent groups excluding single bonds and aromatic groups It is preferable to include the structural unit derived from an aromatic dicarboxylic acid compound. Examples of the aromatic hydrocarbon ring include a monocyclic hydrocarbon ring such as a benzene ring; And polycyclic hydrocarbon rings such as condensed bicyclic hydrocarbon rings such as naphthalene and ring aggregated hydrocarbon rings such as biphenyl, and is preferably a benzene ring. Specifically, equation (IV)

[Formula 11]

[In formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ²⁵ to R ³² are , Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ²⁵ to R ³² may be each independently substituted with a halogen atom, and A is Each independently, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -NR ³³ -, R ³³ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and m represents an integer of 1 to 4]

It is preferable to contain the structural unit derived from the compound represented by (it may be called a structural unit derived from the dicarboxylic acid compound (IV)).

In formula (IV), A is independently -O-, -CH ₂ -, -CH ₂ -, from the viewpoint of easily lowering the drying temperature and easily obtaining an optical film having good bending resistance. CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -NR ³³ -, From the viewpoint of easily obtaining an optical film having excellent bending resistance, preferably -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or -S -Represents, more preferably -O-, -CH ₂ -, -C(CH ₃ ) ₂ -or -SO ₂ -, more preferably -O-. R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ , R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl 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 those illustrated as R ³ to R 6 alkyl groups having 1 to ⁶ carbon atoms. The aryl group of 6 to 12 carbon atoms, may be mentioned as examples of the aryl group having a carbon number of 6 to 12 of the R ³ ~R ^6. The hydrogen atom contained in R ²⁵ to R ³² may be each independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Moreover, as a C6-C12 aryl group substituted by the halogen atom, what was illustrated as a C6-C12 aryl group substituted by the halogen atom of R<^3>-R<^6> is mentioned. R ³³ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom. Examples of the hydrocarbon group having 1 to 12 carbon atoms include those exemplified as an alkyl group having 1 to ⁶ carbon atoms of R ³ to R 6, and examples of aryl groups having 6 to 12 carbon atoms.

In Formula (IV), m represents an integer of 1 to 4, and when m is within this range, an optical film having good flexural resistance and elastic modulus is likely to be obtained. In addition, in Formula (IV), m is preferably an integer of 1 to 3, more preferably 1 or 2, more preferably 1, and if m is within this range, the modulus of elasticity is more likely to be improved.

Among these, R ²⁵ to R ³² are preferably 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, from the viewpoint of easily increasing the bending resistance of the optical film. It is more preferably a hydrogen atom.

In a preferred embodiment of the present invention, the structural unit derived from the compound represented by formula (IV) is represented by formula (IV').

[Formula 12]

It is a structural unit derived from the compound represented by (it may be called a structural unit derived from the dicarboxylic acid compound (IV')). When the polyamideimide resin contains a structural unit derived from the dicarboxylic acid compound (IV'), the bending resistance and transparency of the optical film can be improved. Moreover, the solubility of the polyamideimide resin in the solvent can be improved by the skeleton containing the fluorine element, the viscosity of the polyamideimide varnish can be suppressed to be low, and the production of the optical film becomes easy.

In a suitable aspect of the present invention, the polyamideimide resin of the present invention is a resin containing a structural unit derived from a dicarboxylic acid compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a diamine compound. Moreover, in a more suitable aspect of the present invention, the polyamideimide resin of the present invention is a structural unit derived from a dicarboxylic acid compound (I), a structural unit derived from a tetracarboxylic acid compound (II), or derived from a diamine compound (III). It is a resin which consists of a structural unit and a structural unit derived from a dicarboxylic acid compound (IV). In a more suitable aspect of the present invention, the polyamideimide resin of the present invention is a structural unit derived from a dicarboxylic acid compound (I'), a structural unit derived from a tetracarboxylic acid compound (II'), or a diamine compound (III') It is a resin which consists of a structural unit and a structural unit derived from a dicarboxylic acid compound (IV'). An optical film containing a polyamideimide resin having such a structural unit is advantageous in terms of bending resistance and transparency (especially maintenance of transparency in a high temperature and high humidity environment).

In one embodiment of the present invention, the polyamideimide resin is a structural unit derived from the dicarboxylic acid compound (I) exemplified above, and a dicarboxylic acid compound (IV) within a range that does not impair various physical properties of the optical film. You may include other structural units other than the structural unit derived, the structural unit derived from the tetracarboxylic acid compound (II), and the structural unit derived from the diamine compound (III).

As another structural unit, for example, the structural unit derived from the other dicarboxylic acid compound other than the structural unit derived from the dicarboxylic acid compound (I) and the structural unit derived from the dicarboxylic acid compound (IV), the tetracarboxylic acid compound (II) And structural units derived from other tetracarboxylic acid compounds other than derived structural units, structural units derived from tricarboxylic acid compounds, and structural units derived from other diamine compounds other than structural units derived from diamine compounds (III). In addition, the dicarboxylic acid compound represents a dicarboxylic acid or a dicarboxylic acid derivative (for example, an acid chloride or an acid anhydride of dicarboxylic acid), and the tricarboxylic acid compound is a tricarboxylic acid or a tricarboxylic acid derivative ( For example, it represents an acid chloride or an acid anhydride of tricarboxylic acid, and the tetracarboxylic acid compound represents tetracarboxylic acid or a tetracarboxylic acid derivative (for example, an acid chloride or acid anhydride of tetracarboxylic acid).

As another dicarboxylic acid unit, it is Formula (V), for example.

[Formula 13]

And a structural unit derived from a compound represented by (may be referred to as a structural unit derived from a dicarboxylic acid compound (V)). As a dicarboxylic acid unit, 1 type(s) or 2 or more types of structural units derived from the dicarboxylic acid compound (V) may be included, and when 2 or more types are included, the structural unit derived from each dicarboxylic acid compound (V) Therefore, the types of Z are different.

In formula (V), Z is represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (27) and formula (29) Among the bonding groups of the groups shown, two nonadjacent groups are substituted with hydrogen atoms or a divalent chain hydrocarbon group having 6 or less carbon atoms. R ³⁴ and R ³⁵ are each independently a hydroxyl group (-OH), methoxy group (-OMe), ethoxy group (-OEt), n-propoxy group (-OPr), n-butoxy group (-OBu ) Or chlorine atom (-Cl), preferably chlorine atom (-Cl).

As specific examples of the dicarboxylic acid compound constituting the dicarboxylic acid unit, for example, 4,4'-oxybisbenzoic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3, 3'-biphenyldicarboxylic acid, two benzoic acid single bond, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or a compound connected with a phenylene group, etc. Aromatic dicarboxylic acids and their derivatives (for example, acid chloride, acid anhydride); And aliphatic dicarboxylic acids such as dicarboxylic acid compounds of chain hydrocarbons having 8 or less carbon atoms, and derivatives thereof (for example, acid chlorides and esters). These dicarboxylic acid compounds may be used alone or in combination of two or more. Among these, it is preferable to use together the compound represented by Formula (I) and the compound represented by Formula (IV) in order to achieve both the elastic modulus and the flexibility of the optical film. As a specific example, the combination of 4,4'-oxybis (benzoyl chloride) and terephthaloyl chloride is preferable.

As another tetracarboxylic acid unit, it is Formula (VI), for example.

[Formula 14]

The structural unit derived from the compound represented by (it may be called a structural unit derived from the tetracarboxylic acid compound (VI)), and formula (iv)

[Formula 15]

And a structural unit derived from the compound represented by (may be referred to as a structural unit derived from a tetracarboxylic acid compound (i)). Here, in the polyamideimide resin of the present invention, the structural unit derived from the tetracarboxylic acid compound represented by formula (VI) can be bonded to the structural unit derived from the diamine compound via imide groups formed on both sides of Y. have. In addition, the expression a structural unit of the tetracarboxylic acid compound derived indicated by (Ⅶ), the diamine and the structural units of the compound derived from, there via an amide group formed on deugi and the side of the other one of Y ¹ are formed on the Y ¹ one side Can be combined. As the tetracarboxylic acid unit, one or two or more types of structural units derived from the tetracarboxylic acid compound (VI) and structural units derived from the tetracarboxylic acid compound (VII) may be included. When two or more types of structural units derived from a tetracarboxylic acid compound (VI) and a structural unit derived from a tetracarboxylic acid compound (i) are included, Y in a structural unit derived from two or more types of the tetracarboxylic acid compound (VI) The types are different, and the types of Y ¹ are different in structural units derived from two or more types of tetracarboxylic acid compounds (i).

In formula (VI), Y is a tetravalent organic group, and preferably represents a tetravalent organic group having 4 to 40 carbon atoms. 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 hydrocarbon group substituted with a halogen atom. In this case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8. As Y, group represented by Formula (20), Formula (21), Formula (23), Formula (24), Formula (25) and Formula (27), Formula (28), Formula (29); A group in which the hydrogen atom in the group represented by such a formula is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; Or a tetravalent chain hydrocarbon group having 6 or less carbon atoms. In addition, in formula (VII), Y ¹ is a tetravalent organic group, preferably an organic group in which the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a hydrocarbon group substituted with a halogen atom, and formula (20) and formula Groups represented by (21), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29); A group in which the hydrogen atom in the group represented by such a formula is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; Or a tetravalent chain hydrocarbon group having 6 or less carbon atoms. From the viewpoint of easy to reduce the yellowness of the optical film, in the formula (VI) and formula (i), Y and Y ¹ are represented by formulas (20), (21), (22), and (23). , A group represented by formula (24), formula (25), formula (26) or formula (27); The group in which the hydrogen atom in the group represented by such a formula is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group is preferable. In addition, R ³⁶ and R ³⁷ are each independently a hydroxyl group (-OH), methoxy group (-OMe), ethoxy group (-OEt), n-propoxy group (-OPr), n-butoxy group ( It is preferably -OBu) or chlorine atom (-Cl) and chlorine atom (-Cl).

[Formula 16]

In the formulas (20) to (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 specific examples thereof include a phenylene group. From the viewpoint of easy to improve the elastic modulus of the obtained optical film, in formula (VI) or formula (iv), Y or Y ¹ is preferably a group represented by formula (26), formula (28) or formula (29), respectively. Do. Moreover, W ¹ is independently a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, from the viewpoint of easily suppressing the yellowness of the optical film, It is preferred that -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ -, single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ It is more preferable that it is -, and it is more preferable that it is -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ -.

Examples of the tetracarboxylic acid compound constituting the tetracarboxylic acid unit include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic acid and anhydrides thereof, preferably dianhydrides thereof; Aliphatic tetracarboxylic acid compounds, such as aliphatic tetracarboxylic acid and its anhydride, Preferably its dianhydride, etc. are mentioned. In addition to the anhydride, the tetracarboxylic acid compound may be a derivative of a tetracarboxylic acid compound such as an acid chloride, and these 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 the 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, 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 (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 Water, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4, And 4'-(p-phenylenedioxy)diphthalic dianhydride and 4,4'-(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, 2,3,6, And 7-naphthalene tetracarboxylic acid dianhydride.

Among these, preferably 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, 2,2',3,3'-benzophenone tetracarboxylic acid Dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-di Phenylsulfontetracarboxylic 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-phenylenedioxy)diphthalic dianhydride and 4 And 4'-(m-phenylenedioxy)diphthalic dianhydride, more preferably 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid Dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, bis(3,4-dicarboxyphenyl)methane Dianhydride and 4,4'-(p-phenylenedioxy)diphthalic dianhydride. These may be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic acid dianhydride include cyclic or acyclic aliphatic tetracarboxylic acid dianhydride. 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, 1,2,3,4- Cycloalkanetetracarboxylic dianhydride, such as cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3, And 5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride and their positional isomers. These may be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic acid dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride, and the like, alone or in two. It can be used in combination of more than one species. 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 preferably used from the viewpoint of improving the elastic modulus, bending resistance and optical properties of the optical film. . Specific examples include 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic 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, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and mixtures thereof are preferred, 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4 ,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and mixtures thereof are more preferred, and 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride is more preferred.

As another tricarboxylic acid unit, for example, formula (i)

[Formula 17]

The structural unit derived from the compound represented by (it may be called a structural unit derived from the tricarboxylic acid compound (i)) is mentioned. The tricarboxylic acid compound represents a tricarboxylic acid or a tricarboxylic acid derivative, and examples of the tricarboxylic acid derivative include an acid chloride and an ester body of tricarboxylic acid. When the polyamideimide resin of the present invention contains a structural unit derived from a tricarboxylic acid compound (i), the structural unit derived from a tricarboxylic acid compound (i) is a structural unit derived from a diamine compound and both sides of Y ² It can be bonded via an imide group or an amide group formed on. As the tricarboxylic acid unit, one or two or more types of tricarboxylic acid units (단위) may be included, and when two or more types are included, the types of Y ² in each tricarboxylic acid unit (카르) are different. . Further, R ³⁸ is -OH, -OMe, -OEt, -OPr, -OBu or -Cl, and -Cl is preferred. 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 hydrocarbon group substituted with a halogen atom. Y ² is a formula (20), a formula (21), a formula (22), a formula (23), a formula (24), a formula (25), a formula (26), a formula (27), a formula (28) or a formula The group represented by (29) represents a group in which any one of the bonds of the group is substituted with a hydrogen atom, or a trivalent hydrocarbon group having 6 or less carbon atoms.

When the polyamideimide resin of the present invention includes a tricarboxylic acid unit, as the tricarboxylic acid compound constituting the tricarboxylic acid unit, aromatic tricarboxylic acid, aliphatic tricarboxylic acid and derivatives thereof (for example, acid chloride, Acid anhydrides, etc.), and specific examples thereof include anhydrides of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalene tricarboxylic acid-2,3-anhydride; And a compound in which phthalic anhydride and benzoic acid are single-linked, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, or a phenylene group. These tricarboxylic acid compounds may be used alone or in combination of two or more.

As another diamine unit, it is Formula (iv), for example.

[Formula 18]

And a structural unit derived from the compound represented by (may be referred to as a structural unit derived from a diamine compound (i)). Here, in the polyamideimide resin of the present invention, the structural unit derived from the diamine compound (i) can be bonded to the structural unit derived from dicarboxylic acid via an amide group formed on both sides of X, and a tetracarboxylic acid compound The derived structural unit can be bonded via an imide group or an amide group formed on both sides of X, and can be combined with a structural unit derived from a tricarboxylic acid compound via an imide group or amide group formed on both sides of X. Moreover, as a diamine unit, 1 type(s) or 2 or more types of structural units derived from a diamine compound (i) may be included, and when 2 or more types are included, X kind in the structural unit derived from each diamine compound (i) Is different. X represents a divalent organic group, and preferably represents a divalent organic group having 4 to 40 carbon atoms. The organic group may be substituted with a hydrocarbon group in which the hydrogen atom in the organic group is substituted with a hydrocarbon group or a halogen atom, and in this case, the number of carbon atoms in the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8. As X, group represented by Formula (10), Formula (11), Formula (12), Formula (13), Formula (14), Formula (15), Formula (16) or Formula (17); A group in which the hydrogen atom in the group represented by such a formula is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; Or it represents the chain hydrocarbon group of 6 or less carbon atoms.

[Formula 19]

In formulas (10) to (17), * represents a bond,

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 -or -CO-.

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 preferably meta positions or para positions, and more preferably para positions, for each ring. desirable. 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 easy to improve the elastic modulus of the optical film made of a polyamideimide resin, It is more preferably a single bond or -O-.

As a diamine compound which comprises a diamine unit, an aliphatic diamine, an aromatic diamine, and mixtures thereof are mentioned, for example. In addition, in this embodiment, "aromatic diamine" refers to the diamine in which the amino group is directly bonded to the aromatic ring, and an aliphatic group or other substituent may be included 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. In addition, "aliphatic diamine" refers to a diamine in which an amino group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be included in a part of the structure.

Specific examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylene diamine; And cyclic aliphatic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine, and 4,4'-diaminodicyclohexylmethane. . These may 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 -Aromatic diamine having one aromatic ring, such as diaminonaphthalene; 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)-4,4'-diaminodiphenyl (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) And aromatic diamines having two or more aromatic rings, such as -fluorophenyl)fluorene. These may be used alone or in combination of two or more.

As the aromatic diamine, preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 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)-4,4'-diaminodiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl. These may be used alone or in combination of two or more.

Among the diamine compounds, from the viewpoint of easily improving the mechanical strength (for example, bending resistance and elastic modulus) of the optical film, and also improving optical properties, for example, easy to reduce haze, from aromatic diamines having a biphenyl structure It is preferable to use one or more selected from the group consisting of. 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4 It is more preferable to use at least one member selected from the group consisting of'-diaminodiphenyl ether, and more preferably to use 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl. desirable.

The content of the dicarboxylic acid unit included in the carboxylic acid unit constituting the polyamideimide resin is preferably 20 mol% or more, more preferably 30 mol% or more, based on the total number of moles of all the structural units of the carboxylic acid unit. , 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 85 mol% or less, more preferably 80 mol% or less. When the content of the dicarboxylic acid unit is greater than or equal to the above lower limit, the mechanical strength (for example, modulus of elasticity) of the optical film is likely to be improved by hydrogen bonding between amide bonds derived from the dicarboxylic acid unit. Moreover, when content of a dicarboxylic acid unit is below the said upper limit, the viscosity of the polyamideimide varnish mentioned later can be suppressed by suppressing the thickening by hydrogen bonding between amide bonds derived from a dicarboxylic acid unit, and an optical film It can facilitate processing.

The content of the tetracarboxylic acid unit contained in the carboxylic acid unit constituting the polyamideimide resin is preferably 10 mol% or more, more preferably 20 mol% or more, preferably with respect to the total number of moles of the carboxylic acid units. Is 60 mol% or less, more preferably 50 mol% or less, and more preferably 40 mol% or less. When the content of the tetracarboxylic acid unit is less than or equal to the above upper limit, there is a tendency that mechanical strength (for example, elastic modulus) can be improved. When the content of the tetracarboxylic acid unit is greater than or equal to the above lower limit, solubility in a solvent and optical properties (for example, haze or yellowness) tend to be improved.

In the carboxylic acid unit contained in the polyamideimide resin, the content of the dicarboxylic acid unit is preferably 0.1 mol or more, more preferably 1 mol or more, and more preferably 1 mol of the tetracarboxylic acid unit. It is 2 mol or more, Preferably it is 5 mol or less, More preferably, it is 4 mol or less, More preferably, it is 3 mol or less. When the content of the dicarboxylic acid unit is greater than or equal to the above lower limit, the optical film tends to have a high mechanical strength (e.g., elastic modulus), and if it is equal to or less than the upper limit, the thickening by hydrogen bonding between amide bonds in the dicarboxylic acid unit It can be suppressed, and the viscosity of the polyamideimide varnish can be reduced, making the production of the optical film easy.

Content (R _(I) ) of the structural unit derived from the compound represented by Formula (I) (the structural unit derived from the dicarboxylic acid compound _(I) ) is based on the total number of moles of all the structural units constituting the polyamideimide resin. , Preferably greater than 0 mol%, more preferably at least 5 mol%, more preferably at least 10 mol%, particularly preferably at least 15 mol%, most preferably at least 20 mol%, especially at 25 mol% It is the above, Preferably it is 40 mol% or less, More preferably, it is 35 mol% or less. In addition, the content of the structural unit derived from the compound represented by the formula (I) (the structural unit derived from the dicarboxylic acid compound (I)) is preferably based on the total number of moles of the carboxylic acid units constituting the polyamideimide resin. Is greater than 0 mol%, more preferably at least 10 mol%, more preferably at least 20 mol%, particularly preferably at least 30 mol%, most preferably at least 40 mol%, particularly at least 50 mol%, It is preferably 80 mol% or less, and more preferably 70 mol% or less. When the content of the structural unit derived from the dicarboxylic acid compound (I) is equal to or greater than the above lower limit, the mechanical strength of the optical film (e.g., elastic modulus) is due to structural rigidity derived from the structural unit derived from the dicarboxylic acid compound (I). ) Is easy to improve, and if it is less than or equal to the above upper limit, the viscosity of the polyamideimide varnish to be described later can be suppressed by suppressing the thickening due to hydrogen bonding between amide bonds derived from the structural unit derived from the dicarboxylic acid compound (I). It is possible to facilitate the processing of the optical film. In addition, in this specification, content (mol%) of the structural unit derived from the compound represented by said Formula (I) with respect to the total mole number of the total structural unit which comprises a polyamideimide resin is called R _(I) .

The content of the structural unit (the structural unit derived from the tetracarboxylic acid compound (II)) derived from the compound represented by formula (II) is preferably 5 mol with respect to the total number of moles of the total structural units constituting the polyamideimide resin. % Or more, more preferably 10 mol% or more, preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less. Moreover, content of the structural unit derived from the compound represented by Formula (II) (the structural unit derived from the tetracarboxylic acid compound (II)) is preferably with respect to the total number of moles of the carboxylic acid units constituting the polyamideimide resin. It is 10 mol% or more, more preferably 20 mol% or more, preferably 60 mol% or less, more preferably 50 mol% or less, and more preferably 40 mol% or less. When the content of the structural unit derived from the tetracarboxylic acid compound (II) is greater than or equal to the above lower limit, the mechanical strength (e.g., modulus of elasticity) of the optical film tends to improve, and if the content is less than or equal to the upper limit, the solubility to the solvent or It is easy to improve optical properties (for example, haze or yellowness).

The content of the structural unit derived from the compound represented by formula (III) (the structural unit derived from diamine compound (III)) is preferably 20 mol% or more with respect to the total number of moles of all the structural units constituting the polyamideimide resin. , More preferably 30 mol% or more, more preferably 40 mol% or more, particularly preferably 45 mol% or more, preferably 80 mol% or less, more preferably 70 mol% or less, more preferably 60 mol% or less, particularly preferably 55 mol% or less. Moreover, content of the structural unit derived from the compound represented by Formula (III) (the structural unit derived from the diamine compound (III)) is preferably 30 mol% with respect to the total number of moles of the diamine units constituting the polyamideimide resin. Above, more preferably 50 mol% or more, more preferably 70 mol% or more, and preferably 100 mol% or less. When the content of the structural unit derived from the diamine compound (III) is within the above range, the bending resistance and transparency of the optical film are easily improved, and the solubility of the polyamideimide resin in the solvent is further improved, and the viscosity of the polyamideimide varnish is improved. Can be suppressed lower, and the production of the optical film becomes easier.

The content of the structural unit derived from the compound represented by formula (IV) (the structural unit derived from dicarboxylic acid compound (IV)) is preferably 1.5 mol with respect to the total number of moles of all the structural units constituting the polyamideimide resin. % Or more, more preferably 2.5 mol% or more, more preferably 3.5 mol% or more, particularly preferably 5 mol% or more, preferably 35 mol% or less, more preferably 30 mol% or less. In addition, the content of the structural unit derived from the dicarboxylic acid compound (IV) is preferably 3 mol% or more, more preferably 5 mol% or more, based on the total number of moles of the carboxylic acid units constituting the polyamideimide resin, More preferably, it is 7 mol% or more, particularly preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less. When the content of the structural unit derived from the dicarboxylic acid compound (IV) is greater than or equal to the above lower limit, the flex resistance is easily improved, and when it is equal to or less than the upper limit, the amide derived from the structural unit derived from the dicarboxylic acid compound (IV) By suppressing the thickening due to hydrogen bonding between bonds, the viscosity of the polyamideimide varnish to be described later can be suppressed, and processing of the optical film can be facilitated.

In a preferred embodiment of the present invention, as described above, the polyamideimide resin may include a halogen atom. A fluoro group and a trifluoromethyl group are mentioned as a specific example of a fluorine-containing substituent. When the polyamideimide resin contains a halogen atom, it is easy to improve the transparency of the optical film made of the polyamideimide resin. From the viewpoint of transparency of the optical film, the halogen atom is preferably a fluorine atom.

The content of the halogen atom in the polyamideimide resin is preferably 1 to 40% by mass, more preferably 3 to 35% based on the mass of the polyamideimide resin, from the viewpoint of more easily improving the transparency of the optical film. It is mass %, more preferably 5 to 32 mass %.

The polyamideimide resin of the present invention is prepared by reacting the diamine compound with the carboxylic acid compound containing the dicarboxylic acid compound, the tetracarboxylic acid compound, and the tricarboxylic acid compound as necessary, as described above. . In particular, the compound represented by formula (I), the compound represented by formula (II), the compound represented by formula (III), the compound represented by formula (IV), if necessary, and other carboxylic acids , It is preferably prepared by reaction with other diamines, for example, polycondensation. In one embodiment of the present invention, in the synthesis of the polyamideimide resin, an imidization catalyst may be present. 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, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3 And aromatic amines such as ,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline.

In the production of the polyamideimide resin, the reaction temperature is not particularly limited, but is, for example, 50 to 350°C. Although the reaction time is not particularly limited, it 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. Further, the reaction may be performed in a solvent, and examples of the solvent include a solvent to be described later used in the preparation of a polyamideimide varnish.

In the polyamideimide resin, the weight average molecular weight in terms of the standard polystyrene is preferably 210,000 or more, more preferably 300,000 or more, further preferably 350,000 or more, preferably 750,000 or less, and more preferably 600,000 or less , More preferably 500,000 or less. When the weight average molecular weight of the polyamideimide resin is equal to or greater than the above lower limit, the bending resistance of the optical film made of the polyamideimide resin can be improved. In addition, if the weight average molecular weight of the polyamideimide resin is less than or equal to the above upper limit, the viscosity of the polyamideimide varnish can be suppressed low, and the elongation of the optical film is easy. In addition, in this specification, the weight average molecular weight can be calculated|required by standard polystyrene conversion by performing GPC measurement, for example, and can be specifically determined by the method described in the Example.

In the optical film, the content of the polyamideimide resin is preferably 30 to 99% by mass, more preferably 35 to 95% by mass, more preferably 40 to 90% by mass, particularly with respect to the mass of the optical film It is preferably 50 to 90% by mass. When the content of the polyamideimide resin is within the above range, an optical film excellent in bending resistance and transparency is liable to be obtained.

More specifically, the polyamideimide resin according to a preferred embodiment of the present invention has a repeating structural unit represented by formula (30) and a repeating structural unit represented by formula (33). In addition, the polyamideimide resin according to a preferred embodiment of the present invention is a repeating structural unit represented by any of formulas (31) and (32) within a range that does not impair various physical properties of the resulting polyamideimide polymer film. Any one or more of them may be included. Moreover, the said polyamide-imide resin may contain 2 or more types of repeating structural units represented by Formula (30), Formula (31), Formula (32), and Formula (33), respectively. The repeating structural unit represented by formula (33) is a structural unit formed by a reaction between a dicarboxylic acid compound and a diamine compound, and is a structural unit showing both a structural unit derived from a dicarboxylic acid compound and a structural unit derived from a diamine compound. The repeating structural unit represented by formula (30) is a structural unit formed by reaction of a tetracarboxylic acid compound and a diamine compound, and is a structural unit showing a structural unit derived from a tetracarboxylic acid compound and a structural unit derived from a diamine compound together. The repeating structural unit represented by formula (32) is a structural unit formed by a reaction between a tricarboxylic acid compound and a diamine compound, and is a structural unit showing both a structural unit derived from a tricarboxylic acid compound and a structural unit derived from a diamine compound. The repeating structural unit represented by formula (31) is a structural unit formed by reaction of a tetracarboxylic acid compound and a diamine compound, and is a structural unit showing both a structural unit derived from a tetracarboxylic acid compound and a structural unit derived from a diamine compound.

[Formula 20]

In Formulas (30) to (33), K ¹ and K ³ represent Y in Formula (b), Formula (VI), or Y ¹ in Formula (VII), and K ² represents Formula (a) ), formula (d), or Z in formula (V), K ⁴ represents Y ² in formula ( ^iv ), and L ^{1 to} L ⁴ are formula (c) or formula (iv), respectively. X in) is represented.

[Formula 21]

Equation (a) of the R ³ ~R ⁶ is R ⁷ ~R ¹⁴ in R ⁷ ~R ¹⁴ is formula (Ⅱ) in the formula (Ⅰ) the same as R ³ ~R ^6, and the formula (b) in the the same as the formula (c) of the R ¹⁵ ~R ²² is the same as R ¹⁵ ~R ²² in the formula (ⅲ), and the formula (d) in R ²⁵ ~R ³² is R in the formula (ⅳ) ^{It is the} same as ^{25-R 32,} and * represents a bond.

<silica particles>

The optical film of the present invention may contain silica particles. The average primary particle size of the silica particles is preferably 10 nm or more, more preferably 15 nm or more, more preferably 20 nm or more, preferably 100 nm or less, more preferably 80 nm or less, more preferably 60 nm or less, Especially preferably, it is 40 nm or less. When the average primary particle size of the silica particles is within the above range, aggregation of the silica particles can be suppressed, transparency of the optical film can be improved, and flexibility can be improved. In addition, if the average primary particle size of the silica particles is less than or equal to the above upper limit, the haze value tends to decrease even if the thickness of the optical film is relatively thick. In particular, if the average primary particle size of the silica particles is preferably 80 nm or less, more preferably 60 nm or less, for example, even if the thickness of the optical film is 30 μm or more, a low haze value, preferably 1.0% or less, more preferably Haze value of 0.8% or less (corresponding to Hz _b ) may be displayed. In addition, in this invention, the average primary particle diameter can be measured by BET method.

<optical film>

The optical film of the present invention comprises the polyamideimide resin, and formula (1)

ΔHz<0.5 (One)

[In formula (1), ΔHz denotes Hz _a -Hz _b , and Hz _a is a mandrel test that returns to a flat shape by bending once with a bending radius of 1 mm at room temperature (JIS K 5600-5-1:1999) ), haze (%) of the optical film after, _b Hz represents the haze (%) of the optical film before the mandrel test]

Meets the relationship. Since the optical film of the present invention satisfies the relationship of formula (1), it has excellent flexural resistance and excellent stability of optical properties under high temperature and high humidity. In addition, the optical film of the present invention has low haze and the like and is excellent in transparency. That is, even if the optical film of the present invention is repeatedly bent and returned to the optical film continuously, scratches, cracks, cloudiness, and the like are unlikely to occur in the optical film, and excellent optical properties such as transparency can be maintained. Furthermore, even when the optical film is stored in a bent state under high temperature and high humidity, for example, at an environment of 85° C. and 85% relative humidity, scratches, cracks, cloudiness, etc. are unlikely to occur in the optical film, and excellent optical properties such as transparency Characteristics can be maintained. Therefore, the optical film of the present invention can be used as a member of an image display device, particularly a front panel (window film) of a flexible display or the like. In order to be used for a front panel (window film) of a flexible display, from the viewpoint of durability when repeatedly used, the ΔHz' before and after storage for 24 hours under an environment of 85°C and 85% relative humidity is less than 0.4, preferably 0.3. Hereinafter, more preferably, it should be 0.2 or less. In addition, ΔHz' can be calculated by measuring by the method described in Examples.

The front plate has a function of protecting an image display element in a flexible display. 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, such as 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 watch, and a wearable device.

In Formula (1), ΔHz represents Hz _a -Hz _b , and Hz _a is the haze of the optical film after the mandrel test to bend once under a bending radius of 1 mm at room temperature and in an atmosphere in the air, and immediately return. %). More specifically, ΔHz can be calculated by measuring by the method described in Examples. Hz _b represents the haze (%) of the optical film before the mandrel test. ΔHz represents the amount of haze change of the optical film before and after the mandrel test (flexibility test), and the smaller the value, the higher the stability of the optical properties at bending. In addition, the composition of the optical film, for example, the type and composition ratio of the repeating structure constituting the polyamideimide resin constituting the optical film, and the type and content of additives such as silica particles and ultraviolet absorbers contained in the optical film; The thickness of the optical film; Or it can adjust to the range of Formula (1) by suitably adjusting the manufacturing conditions of an optical film, for example, varnish solvent type, drying temperature, drying time, etc. Particularly, when silica particles having an average primary particle diameter of less than or equal to the above upper limit are used, transparency can be improved, and thus it is easy to adjust in the range of formula (1).

In the formula (1), Hz _b is usually preferably 20.0% or less, more preferably 2.0% or less, still more preferably 1.0% or less, particularly preferably 0.8% or less. If it is the said range, an optical film can have favorable transparency, and when used for the front plate of an image display apparatus, it can contribute to high visibility. In addition, ΔHz is less than 0.5%, more preferably 0.4% or less, more preferably 0.3% or less, even more preferably 0.1% or less. When ΔHz is within the above range, the optical film has better bending resistance and can effectively maintain optical properties such as transparency even at high temperatures and high humidity.

Moreover, it is preferable that the optical film of this invention contains the said silica particle, Formula (2)

0<R _Si ≤32+2/3×R _(I) (2)

[In formula (2), R _Si represents the content (mass %) of silica particles with respect to the mass of the optical film, and R _(I) represents the formula (I) with respect to the total number of moles of all constituent units constituting the polyamideimide resin. ) Represents the content (mol%) of the structural unit derived from the compound]

It is desirable to satisfy the relationship.

In formula (2), R _Si is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, preferably less than 60% by mass, more preferably It is 50 mass% or less. When the content of the silica particles is greater than or equal to the above lower limit, the elastic modulus and flexural resistance of the optical film can be further improved, and when the content of the silica particles is less than or equal to the upper limit above, for example, haze is reduced and transparency is further improved. Can. In addition, in one embodiment, even if the content of the silica particles is relatively large, the optical film of the present invention can suppress the aggregation of the silica particles, ensure good transparency, and have excellent stability of optical properties under high temperature and high humidity. In addition, since good bending resistance is also obtained, R _Si may be 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, and 50 parts by mass or more.

The optical film of the present invention may further include an ultraviolet absorber. As the ultraviolet absorber, for example, triazine derivatives such as benzotriazole derivatives (benzotriazole-based ultraviolet absorbers) and 1,3,5-triphenyltriazine derivatives (triazine-based ultraviolet absorbers), benzophenone derivatives (benzophenone series Ultraviolet absorbers) and salicylate derivatives (salicylate-based ultraviolet absorbers), and at least one selected from the group consisting of these can be used. It is preferable to use at least 1 sort(s) selected from the group which consists of a benzotriazole type ultraviolet absorber and a triazine type ultraviolet absorber from a point which has favorable ultraviolet absorbing ability, and a benzotriazole type ultraviolet absorber is more preferable.

As a specific example of a benzotriazole type ultraviolet absorber, the compound represented by Formula (A) is mentioned, These can be used individually or in combination of 2 or more types. As a specific example of the compound represented by Formula (A), Sumitomo Chemical Co., Ltd. trade name: Sumisorb(trademark) 200(2-(2-hydroxy-5-methylphenyl)benzotriazole), Sumisorb 300(2- (3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chlorobenzotriazole), Sumisorb 340 (2-(2-hydroxy-5-tert-octylphenyl)benzotriazole), Sumisorb 350 (2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole).

[Formula 22]

In formula (A), T is a hydrogen atom, a fluorine atom, a chlorine atom, an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms, and R ³⁹ and R ⁴⁰ are each independently a hydrogen atom or 1 to 20 carbon atoms. Is a hydrocarbon group of, and at least one of R ³⁹ and R ⁴⁰ is a hydrocarbon group having 1 to 20 carbon atoms.

Examples of the alkyl group having 1 to 5 carbon atoms in T are 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, and the like.

Examples of the alkoxy group having 1 to 5 carbon atoms in T include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, and n-pentyloxy group. , 2-methyl-butoxy group, 3-methylbutoxy group, 2-ethyl-propoxy group, and the like.

T is preferably a hydrogen atom, a fluorine atom, a chlorine atom or a methyl group, and more preferably a hydrogen atom, a fluorine atom or a chlorine atom.

R ³⁹ and R ⁴⁰ are each a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and at least one of R ³⁹ and R ⁴⁰ is a hydrocarbon group. When R ³⁹ and R ⁴⁰ are each a hydrocarbon group, they are preferably a hydrocarbon group having 1 to 12 carbon atoms, and more preferably a hydrocarbon group having 1 to 8 carbon atoms. Specifically, a methyl group, tert-butyl group, tert-pentyl group, and tert-octyl group are illustrated.

In the optical film, the content of the ultraviolet absorber is preferably from 0.01 to 10 parts by mass, more preferably from 1 to 8 parts by mass, further preferably from 100 parts by mass of the polyamideimide resin and silica particles. 3 to 7 parts by mass. When the content of the ultraviolet absorber is greater than or equal to the above lower limit, ultraviolet absorbency can be improved. When the content of the ultraviolet absorber is equal to or less than the above upper limit, decomposition of the ultraviolet absorber due to heat during optical film production can be suppressed, and the transparency of the optical film is easily improved.

The optical film of the present invention may contain additives other than the polyamideimide resin, the silica particles, and the ultraviolet absorber. Examples of the other additives include other resins other than polyamideimide resins, antioxidants, mold release agents, stabilizers, colorants such as bluening agents, flame retardants, lubricants, and leveling agents. Other additives may be used alone or in combination of two or more. When the optical film contains an additive, the content of the additive is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass relative to the mass of the optical film.

The other resin is not particularly limited, and conventional resins such as polyolefin resins, cellulose resins, polyester resins, polycarbonate resins, (meth)acrylic resins, polystyrene resins, and polyether ether ketone resins, And polysulfone-based resins and polyimide-based resins. Other resins may be used alone or in combination of two or more.

The thickness of the optical film is appropriately adjusted depending on the application, but is usually 10 to 200 μm, preferably 20 to 100 μm, more preferably 25 to 80 μm, and even more preferably 30 to 50 μm. When the thickness of the optical film is within the above range, the bending resistance and transparency are improved. In addition, in this invention, the thickness of an optical film can be measured by the method described in an Example, for example.

In the optical film of the present invention, the total light transmittance at a thickness of 50 µm is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more, particularly preferably 91% or more, Most preferably 92% or more. An optical film in which the total light transmittance of the optical film is greater than or equal to the above lower limit has good transparency and can contribute to high visibility when used in the front panel of an image display device. In addition, the upper limit of the total light transmittance is usually 99.99% or less. In addition, the total light transmittance can be measured by, for example, a fully automatic direct haze computer HGM-2DP manufactured by Suga Tester Co., Ltd., or an ultraviolet visible near spectrophotometer V-670 manufactured by Nippon Spectroscope Co., Ltd. When an optical film is applied to, for example, a liquid crystal display, the transmittance of the film is high, so that the same brightness can be obtained on the viewer side even when the power of a light source such as a backlight is lowered compared with the case where the transmittance is low. have.

The modulus of elasticity of the optical film of the present invention is preferably 3 GPa or more, more preferably 4 GPa or more, more preferably 5 GPa or more, particularly preferably 6 GPa or more, preferably 10 GPa or less, more preferably 8 GPa or less, More preferably, it is 7 GPa or less. When the elastic modulus of the optical film is within the above range, the bending resistance of the optical film is likely to be improved. In addition, the elastic modulus is measured from the slope by measuring an SS curve under conditions of 500 mm chuck distance and a tensile speed of 20 mm/min for a specimen having a width of 10 mm, using an autograph AG-IS manufactured by Shimadzu Corporation, for example. can do.

Although the manufacturing method of an optical film is not specifically limited, For example, the following process:

(a) A step of preparing a liquid (sometimes referred to as a polyamideimide varnish) containing a polyamideimide resin and silica particles (a polyamideimide varnish preparation step),

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

(c) It can be manufactured by a method including drying the applied liquid (coating film) and forming an optical film (optical film forming process).

In the step of preparing a polyamideimide varnish, for the preparation of a polyamideimide varnish, the dicarboxylic acid compound, the tetracarboxylic acid compound, the diamine compound, and, if necessary, the tricarboxylic acid compound, and an imidization catalyst Other components such as a tertiary amine acting and a dehydrating agent are mixed and reacted to prepare a polyamideimide resin mixed solution. As a tertiary amine, the aromatic amine, aliphatic amine, etc. which were mentioned above are mentioned. Examples of the dehydrating agent include acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, and isogilacetic anhydride. A poor solvent is added to the polyamideimide resin mixture, and a polyamideimide resin is precipitated by a reprecipitation method, followed by drying to obtain a precipitate. If necessary, the precipitate is washed with a solvent such as methanol and dried to obtain a polyamideimide resin. Subsequently, a polyamideimide varnish is prepared by dissolving the polyamideimide resin in a solvent and adding and stirring the silica particles and, if necessary, the ultraviolet absorber or other additives. Further, even if a silica sol dispersion medium containing silica particles is added to a polyamideimide resin by dissolving a solvent in which the polyamideimide resin is soluble, for example, a solvent used in the preparation of the following polyamideimide varnish and a silica sol. do.

The solvent used for preparing the polyamideimide varnish is not particularly limited as long as the polyamideimide resin is soluble. Examples of such a solvent include amide solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; lactone-based solvents such as γ-butyrolactone and γ-valerolactone; 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 solvents, lactone-based solvents such as γ-butyrolactone and γ-valerolactone are preferable for preparing the varnish to which silica sol is added. In addition, the polyamideimide varnish may include water, an alcohol-based solvent, a ketone-based solvent, an acyclic ester-based solvent, an ether-based solvent, and the like.

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, roll coating method such as 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 an optical film formation process, an optical film can be formed by drying and peeling from a base material. After peeling, a drying step of further drying the optical film may be performed. 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 PET films, PEN films, polyimide films, and polyamideimide films. Among these, PET films, PEN films, polyimide films, and other polyamideimide films are preferred from the viewpoint of excellent heat resistance. Moreover, a PET film is more preferable from a viewpoint of adhesiveness with an optical film and cost.

A laminated film to which a functional layer such as a hard coating layer, an adhesive layer, and a color adjustment layer is added to the optical film of the present invention can also be formed.

In addition, in providing the optical film of the present invention to a mounting device for a display device, a protective film can be attached to the surface of the film in order to prevent contamination of the film during transportation of the optical film.

[Example]

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the examples, "%" and "part" mean mass% and parts by mass unless otherwise specified. First, a measurement and evaluation method will be described.

<ΔHz at room temperature (25°C)>

The optical film obtained in Examples and Comparative Examples was cut to a size of 68 mm x 28 mm using a dumbbell cutter, and the optical before the mandrel test using a haze computer (manufactured by Suga Tester Co., Ltd., "HGM-2DP"). The haze (Hz _b ) (%) of the film was measured. Then, the following mandrel test (according to JIS K 5600-5-1:1999) was performed, and Hz _a (%) was measured. First, at a room temperature (25° C.), along the cylindrical mandrel having a bend radius of 1 mm, the point where the haze (Hz _b ) (%) of the optical film was measured was evenly bent. Immediately thereafter (after 1 to 2 seconds), the bent optical film was returned to a flat shape, and the haze (Hz _a ) (%) of the bent portion of the flat-shaped optical film was measured. ΔHz (=Hz _a -Hz _b ) was calculated from the measurement results, and evaluated as follows.

○… ΔHz<0.5

×… ΔHz≥0.5

<ΔHz at 85°C and 85% relative humidity storage>

The optical film obtained in Examples and Comparative Examples was cut to a size of 68 mm×28 mm using a dumbbell cutter, and the haze of the optical film obtained using a haze computer (manufactured by Suga Tester Co., Ltd., “HGM-2DP”). (Hz _d ) (%) was measured. Then, the following durability test was performed, and Hz _c (%) after the test was measured. First, a constant temperature and humidity environment endurance tester (manufactured by Yuasa Systems Equipment Co., Ltd., ``CL09-type01D01-FSC90''), and the optical film bent at a bending radius of 1 mm was put into a location where haze (Hz _d ) (%) was measured. , Bend radius 1 mm (both ends of the bent optical film are kept parallel), the optical film was stored for 24 hours in an environment at a temperature of 85° C. and a relative humidity of 85%. Thereafter, the bent optical film was returned to a flat shape, and allowed to stand for 30 minutes under a 30°C relative humidity 50% environment. The haze (Hz _c ) (%) of the bent portion of the planar optical film was measured. ΔHz' (=Hz _c -Hz _d ) was calculated from the measurement results, and evaluated as follows.

○… ΔHz'<0.4

×… ΔHz'≥0.4

<Flexibility test>

The optical films obtained in Examples and Comparative Examples were cut to a size of 10 mm×100 mm using a dumbbell cutter. The cut film was set on the main body of the MIT internal fatigue tester ("MIT-DA" manufactured by Toyo Kogyo Co., Ltd.:0530), and the test speed was 175 cpm, the bending angle was 135 degrees, the weight was 750 g, and the condition of R 1.0 mm of the bending clamp In, a bending test was performed in both front and rear directions, and the number of times of bending of each film (the number of times that could be bent without breaking) was measured. It evaluated as follows.

○… Good bending resistance is more than 10,000 times

×… Less than 10,000 times of bending resistance and bad

<Weight average molecular weight (Mw)>

Gel permeation chromatography (GPC) measurements

· Pretreatment method

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

· Measuring conditions

Column: TSKgel SuperAWM-H×2+SuperAW2500×1 (6.0mm I.D.×150mm×3 pieces)

Eluent: DMF (addition of 10 mM lithium bromide)

Flow rate: 1.0 mL/min.

Detector: RI detector

Column temperature: 40℃

Injection volume: 100μL

Molecular weight standard: standard polystyrene

<Optical film thickness>

The optical film obtained in Examples and Comparative Examples was measured for the thickness of the optical film using an ABS Digimatic Indicator (manufactured by Mitutoyo Corporation, "ID-C112BS").

(Preparation of silica sol)

When the BET diameter (average primary particle diameter measured by the BET method) produced by the sol-gel method is an amorphous silica sol of 27 nm as a raw material, γ-butyrolactone (hereinafter, also referred to as GBL) by solvent substitution Ex) The substituted silica sol was prepared. The obtained sol was filtered through a membrane filter of 10 µm mesh to obtain a GBL-substituted silica sol. The obtained GBL-substituted silica sol had a silica component (inorganic particles) of 30% by mass.

(Preparation of polyamideimide resin)

1. Synthesis Example 1

Under a nitrogen gas atmosphere, in a 1L separable flask with a stirring vane, 65 g (202.97 mmol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (TFMB) and N,N -834.69 g of dimethylacetamide (DMAc) was added and TFMB was dissolved in DMAc while stirring at room temperature. Next, 27.09 g (60.98 mmol) of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added to the flask and stirred at room temperature for 3 hours. Thereafter, 12.00 g (40.66 mmol) of 4,4'-oxybis(benzoylchloride) (OBBC), followed by 20.63 g (101.64 mmol) of terephthaloyl chloride (TPC) was added to the flask, and stirred at room temperature for 1 hour. . Subsequently, 6.63 g (71.15 mmol) of 4-methylpyridine and 18.68 g (182.95 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 stirred for an additional 3 hours. By doing, a reaction solution was obtained.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread shape, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100°C to obtain a polyamideimide resin (TPC/6FDA/OBBC/TFMB=50/30/20/100). The polyamideimide resin had a weight average molecular weight (Mw) of 310,000.

2. Synthesis Example 2

Under a nitrogen gas atmosphere, 40 g (124.91 mmol) of TFMB and 682.51 g of DMAc were added to a 1 L separable flask equipped with a stirring blade, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 16.78 g (37.77 mmol) of 6FDA was added to the flask and stirred at room temperature for 3 hours. Thereafter, OBBC 3.72 g (12.59 mmol), and then TPC 15.34 g (75.55 mmol) were added to the flask and stirred at room temperature for 1 hour. Subsequently, 8.21 g (88.14 mmol) of 4-methylpyridine and 15.43 g (151.10 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 stirred for 3 hours. By doing, a reaction solution was obtained.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread shape, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100°C to obtain a polyamideimide resin (TPC/6FDA/OBBC/TFMB=60/30/10/100). The polyamideimide resin had a weight average molecular weight (Mw) of 400,000.

3. Synthesis Example 3

Under a nitrogen gas atmosphere, to a 1 L separable flask equipped with a stirring vane, TFMB 53.05 g (165.66 mmol) and DMAc 670.91 g were added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 22.11 g (49.77 mmol) of 6FDA, 4.88 g (16.59 mmol) of 3,3',4,4'' phenyltetracarboxylic dianhydride (BPDA) was added to the flask, followed by TPC 20.21 g (99.54 mmol) ) Was added and stirred at room temperature for 1 hour. Subsequently, 10.53 g (133.08 mmol) of pyridine and 13.77 g (134.83 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 stirred for an additional 3 hours to react. Liquid was obtained.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in a thread shape, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100°C to obtain a polyamideimide. The polyamideimide had a weight average molecular weight (Mw) of 190,000.

4. Synthesis Example 4

In a nitrogen atmosphere, 1.25 g of isoquinoline was added to a reaction vessel connected to a vacuum pump equipped with a solvent trap and a filter. Next, 375.00 g of GBL and 104.12 g of TFMB were added to the reaction vessel, and the mixture was dissolved by stirring. In addition, after adding 145.88 g of 6FDA to the reaction vessel, the temperature was started in the oil bath while stirring the mixture. The molar ratio of the added TFMB and 6FDA was 1.00:0.99, and the monomer concentration in the mixture was 40% by mass. When the internal temperature of the reaction vessel reached 80°C, the pressure was reduced to 650 mmHg, and then the temperature was raised to 180°C. After the inner temperature reached 180°C, heating and stirring was further performed for 4 hours. Thereafter, the pressure was reduced to atmospheric pressure, and the inner temperature was cooled to 155°C to obtain a polyimide solution. GBL was added at 155°C to prepare a homogeneous solution having a solid content of 24% by mass of the polyimide, and then a polyimide varnish (1) as a homogeneous solution was taken out from the reaction vessel. When GPC measurement was performed on the polyimide in the obtained polyimide varnish, the weight average molecular weight (Mw) was 360,000.

(Optical film)

1. Examples 1 to 4

The polyamideimide resin (TPC/6FDA/OBBC/TFMB=50/30/20/100) obtained in Synthesis Example 1 was diluted with GBL, and GBL-substituted silica sol was added and mixed sufficiently to obtain the composition shown in Table 1. A resin/silica particle mixing varnish was obtained. At that time, a mixed varnish was prepared so that the concentration of the resin and silica particles was 8.0 to 15.0 mass%. After filtering the obtained polyamide-imide varnish with a filter having a mesh of 10 µm, an applicator was used on the smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") so that the film thickness of the freestanding film was 55 µm. After coating and drying at 50°C for 30 minutes and then at 140°C for 15 minutes, the obtained coating film was peeled off from the polyester substrate to obtain a freestanding film. The freestanding film was fixed to a metal frame, and further dried at 200° C. for 40 minutes in the air to obtain a polyamideimide film (optical film) having a thickness of 50 μm.

2. Examples 5 to 8 and Comparative Example 1

Example except that the polyamideimide resin (TPC/6FDA/OBBC/TFMB=50/30/20/100) obtained in Synthesis Example 2 was changed to TPC/6FDA/OBBC/TFMB=60/30/10/100 Similar to 1 to 4, polyamideimide films (optical films) containing silica particles were obtained.

3. Example 9

50 was similar to Example 2 except that the polyamideimide resin obtained in Synthesis Example 1 was changed to the polyamideimide resin obtained in Synthesis Example 3 (TPC/6FDA/BPDA/TFMB=60/30/10/100). A polyamideimide film (optical film) having a thickness of µm was obtained.

4. Example 10

A polyamideimide film (optical film) having a thickness of 50 µm was obtained in the same manner as in Example 6, except that the average primary particle size of the silica particles was changed to 20 nm.

5. Example 11

The thickness of 50 µm, as in Example 5, except that the content (R _Si ) of the silica particles in the polyamideimide film (optical film) was 10 mass% and the average primary particle size of the silica particles was changed to 83 nm. A polyamideimide film (optical film) was obtained.

6. Comparative Example 2

The polyamideimide resin (TPC/6FDA/BPDA/TFMB=60/30/10/100) obtained in Synthesis Example 3 was diluted with DMAc to prepare a polyamideimide varnish having a concentration of 22% by mass. After filtering the obtained polyamide-imide varnish with a filter having a mesh of 10 µm, an applicator was used on the smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") so that the film thickness of the freestanding film was 55 µm. After coating and drying at 50°C for 30 minutes and then at 140°C for 15 minutes, the obtained coating film was peeled off from the polyester substrate to obtain a freestanding film. The freestanding film was fixed to a metal frame, and further dried at 200° C. for 40 minutes in the air to obtain a polyamideimide film (optical film) having a thickness of 50 μm.

7. Comparative Example 3

The polyimide resin (6FDA/TFMB=100/100) obtained in Synthesis Example 4 was diluted at a ratio of GBL/DMAc=10/90 to prepare a polyimide varnish having a concentration of 15.7% by mass. The obtained polyimide varnish was filtered through a filter having a mesh size of 10 μm, and then applied using an applicator so that the film thickness of the freestanding film was 55 μm on a smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name “A4100”). After drying at 50°C for 30 minutes and then at 140°C for 15 minutes, the obtained coating film was peeled off from the polyester substrate to obtain a freestanding film. The freestanding film was fixed to a metal frame, and further dried at 200° C. for 40 minutes in the air to obtain a polyimide film (optical film) having a thickness of 50 μm.

8. Comparative Example 4

The resin/silica particle mixing varnish was obtained by diluting the polyimide resin (6FDA/TFMB=100/100) obtained in Synthesis Example 4 with GBL and adding GBL-substituted silica sol to thoroughly mix. At that time, a mixed varnish was prepared so that the concentration of the resin and silica particles was 15.0% by mass. The obtained polyimide varnish was filtered through a filter having a mesh size of 10 μm, and then applied using an applicator so that the film thickness of the freestanding film was 55 μm on a smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name “A4100”). After drying at 50°C for 30 minutes and then at 140°C for 15 minutes, the obtained coating film was peeled off from the polyester substrate to obtain a freestanding film. The freestanding film was fixed to a metal frame, and further dried at 200° C. for 40 minutes in the air to obtain a polyimide film (optical film) having a thickness of 50 μm.

Table 1 shows the evaluation results of ΔHz at room temperature, ΔHz at a temperature of 85° C., and relative humidity of 85%, and the bending resistance test of the optical films obtained in Examples 1 to 11 and Comparative Examples 1 to 4. In addition, in Table 1, the ratio of the structural units constituting the polyamideimide resin is from Examples 1 to 8, 10, 11 and Comparative Example 1, the constituent units derived from TPC/6 constituents derived from FDA/OBBC derived The ratio (mol%) of the structural unit/TFMB-derived structural unit is shown, and in Example 9 and Comparative Example 2, the structural unit derived from TPC/6 structural unit derived from FDA/BPDA-derived structural unit/TFMB-derived structural unit The ratio (mole%) of is shown, and for the comparative examples 3 and 4, the ratio (mole%) of the structural unit derived from 6FDA/structural unit derived from TFMB is shown.

In the optical films of Examples 1 to 11, the number of bending resistances in the flexural resistance test was 10,000 or more, and excellent in bending resistance, and compared to the optical films in Comparative Examples 1 to 4, the temperature was 85°C. It was confirmed that ΔHz at 85% humidity storage was remarkably low. Therefore, the optical films of Examples 1 to 11 can achieve excellent bending resistance and stability of excellent optical properties under high temperature and high humidity.

Claims (9)

An optical film comprising a polyamideimide resin and silica particles having an average primary particle diameter of 100 nm or less,
Equation (1)
ΔHz<0.5 (1)
[In formula (1), ΔHz denotes Hz _a -Hz _b , and Hz _a is a mandrel test that returns to a flat shape by bending once with a bending radius of 1 mm at room temperature (JIS K 5600-5-1:1999). Conformity) represents the haze (%) of the optical film after, Hz _b represents the haze (%) of the optical film before the mandrel test]
The polyamideimide resin satisfies the relationship of, and the polyamideimide resin is a resin containing a structural unit derived from a dicarboxylic acid compound, a structural unit derived from a tetracarboxylic acid compound, and a structural unit derived from a diamine compound, derived from the dicarboxylic acid compound The structural unit is represented by formula (I)

[In formula (I), R ¹ and R ² each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ³ to R ⁶ are each Independently, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ³ to R ⁶ may be each independently substituted with a halogen atom] The optical film containing the structural unit of, the content of the said silica particle with respect to the mass of the said optical film is 5-50 mass %, and the thickness of this optical film is 20-100 micrometers. According to claim 1,
Hz _b in Formula (1) is 1.0% or less of an optical film. The method according to claim 1 or 2,
The average particle size of the silica particles is 80 nm or less, the optical film. The method according to claim 1 or 2,
The structural unit derived from the tetracarboxylic acid compound constituting the polyamideimide resin is represented by formula (II)

[In the formula (II), R ⁷ to R ¹⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ⁷ to R ¹⁴ are each independently May be substituted with a halogen atom]
The structural unit derived from the diamine compound which comprises the structural unit derived from the compound represented by and which comprises the said polyamideimide resin is Formula (III).

[In formula (III), R ¹⁵ to R ²² each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹⁵ to R ²² are each Independently, it may be substituted with a halogen atom]
The optical film containing the structural unit derived from the compound represented by. The method of claim 3,
The structural unit derived from the tetracarboxylic acid compound constituting the polyamideimide resin is represented by formula (II)

[In the formula (II), R ⁷ to R ¹⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ⁷ to R ¹⁴ are each independently May be substituted with a halogen atom]
The structural unit derived from the diamine compound which comprises the structural unit derived from the compound represented by and which comprises the said polyamideimide resin is Formula (III).

[In formula (III), R ¹⁵ to R ²² each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹⁵ to R ²² are each Independently, it may be substituted with a halogen atom]
The optical film containing the structural unit derived from the compound represented by. The method according to claim 1 or 2,
The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin is represented by formula (IV)

[In formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ²⁵ to R ³² are , Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ²⁵ to R ³² may be each independently substituted with a halogen atom, and A is Each independently, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -NR ³³ -, R ³³ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and m represents an integer of 1 to 4]
The optical film containing the structural unit derived from the compound represented by. The method of claim 3,
The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin is represented by formula (IV)

[In formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ²⁵ to R ³² are , Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ²⁵ to R ³² may be each independently substituted with a halogen atom, and A is Each independently, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -NR ³³ -, R ³³ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and m represents an integer of 1 to 4]
The optical film containing the structural unit derived from the compound represented by. The method of claim 4,
The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin is represented by formula (IV)

[In formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ²⁵ to R ³² are , Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ²⁵ to R ³² may be each independently substituted with a halogen atom, and A is Each independently, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -NR ³³ -, R ³³ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and m represents an integer of 1 to 4]
The optical film containing the structural unit derived from the compound represented by. The method of claim 5,
The structural unit derived from the dicarboxylic acid compound constituting the polyamideimide resin is represented by formula (IV)

[In formula (IV), R ²³ and R ²⁴ each independently represent a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group or a chlorine atom, and R ²⁵ to R ³² are , Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ²⁵ to R ³² may be each independently substituted with a halogen atom, and A is Each independently, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -NR ³³ -, R ³³ represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and m represents an integer of 1 to 4]
The optical film containing the structural unit derived from the compound represented by.