WO2013125419A1

WO2013125419A1 - Optical film, polarizer, and liquid crystal display device

Info

Publication number: WO2013125419A1
Application number: PCT/JP2013/053450
Authority: WO
Inventors: 一成中原; 宏佳木内; 福坂　潔; 鈴木　隆嗣
Original assignee: コニカミノルタ株式会社
Priority date: 2012-02-22
Filing date: 2013-02-14
Publication date: 2013-08-29
Also published as: JPWO2013125419A1; CN104245851B; CN104245851A

Abstract

The present invention addresses the problem of providing an optical film in which bleed out is inhibited, and which has low internal haze, and exhibits excellent brittleness, high retardation development properties, light resistance, and wet heat resistance. This optical film contains a thermoplastic resin, and a compound represented by general formula (1). (In general formula (1), X₁ represents an oxygen atom or a sulfur atom; Y₁ represents an oxygen atom, a sulfur atom, a nitrogen atom, or NR₄₁; Z₁ represents an oxygen atom, a nitrogen atom, or a sulfur atom; R₁₁, R₂₁ and R₃₁ represent a substituent; R₄₁ represents a hydrogen atom or a substituent; k1 represents an integer between 1 and 5; m1 represents an integer between 0 and 4; n1 represents an integer between 0 and 4; and the dash line represents a single bond or a double bond.)

Description

Optical film, polarizing plate and liquid crystal display device

The present invention relates to an optical film, a polarizing plate, and a liquid crystal display device. More specifically, the present invention relates to an optical film containing a thermoplastic resin, a polarizing plate provided with the optical film, and a liquid crystal display device.

Thermoplastic resin films such as cellulose ester, polycarbonate, and polyolefin are used for optical films, mainly optical compensation films for liquid crystal display devices. Among them, an optical film (cellulose ester film) containing a cellulose ester is widely used because of its excellent bonding property to a polyvinyl alcohol film used as a polarizer. Since the cellulose ester film itself does not have sufficient birefringence necessary for the optical compensation film, various studies have been made to impart birefringence to the cellulose ester film.

In recent years, development of thin and light notebook PCs and thin and large-screen TVs has progressed, and accordingly, optical compensation films for liquid crystal display devices have been increasingly demanded for thinner, larger and higher performance. The humidity durability of the cellulose ester film depends on the film thickness, and can be improved by reducing the film thickness. On the other hand, when the film thickness is reduced, the retardation value decreases. Therefore, an additive (retardation developing agent) having a high retardation increasing ability is required.

For example, a 1,3,5-triazine compound has been proposed as a compound having a high retardation increasing ability (see, for example, Patent Document 1). However, even when the compound was used, the retardation expression was insufficient. Further, it has been found that a polarizing plate produced using a thinned optical compensation film containing this compound and a liquid crystal display device using the same are inferior in durability such as light resistance and wet heat resistance. Furthermore, when placed under high temperature and high humidity, problems such as front contrast unevenness and viewing angle deterioration were also observed. Moreover, when the said compound was added, the brittleness of the film deteriorated and there was a problem in slitting characteristics.

On the other hand, a technique of adding a benzoxazinone compound to a cellulose ester as an ultraviolet absorber has been disclosed (see, for example, Patent Document 2, Patent Document 3, and Patent Document 4). However, even when the compound was added to cellulose ester to produce an optical film, the retardation expression was low. Moreover, since the said compound was incompatible with a cellulose ester, it was easy to bleed out, and the haze value after an internal haze or extending | stretching was large, Therefore, it was a film with a low contrast.

As described above, the conventionally known retardation developing agents are not sufficiently retarded and have problems such as durability and visibility, and further improvements are desired.

Further, a compound having a benzoxazinone skeleton is known as an ultraviolet absorber, but is not known as a retardation developer.

JP 2006-188718 A JP 2009-185217 A JP 2005-504047 gazette JP 2009-20399 A

The present invention has been made in view of the above-mentioned problems and circumstances, and the solution is to have high retardation expression, bleed out is suppressed, internal haze is low, brittleness is excellent, and light resistance is also achieved. It is to provide an optical film having high heat and heat resistance.

A further object of the present invention is to provide a polarizing plate provided with the optical film and having good light resistance and wet heat resistance, and providing a liquid crystal display device excellent in front contrast unevenness and viewing angle deterioration over time. It is to be.

In order to solve the above-mentioned problems, the inventors have investigated the cause of the above-mentioned problem and the like, and a film obtained by adding a benzoxazinone compound having a specific structure to a thermoplastic resin has high retardation expression. And found low internal haze. Specifically, by introducing a substituent with —OCO— as a linking group to a phenyl group substituted at a specific position with respect to the benzoxazinone skeleton, the interaction with the cellulose ester is improved and the compatibility is improved. It has been found that the optical film exhibits high retardation by improving the orientation. Furthermore, it has been found that the optical film to which the benzoxazinone compound having the specific structure is added has good bleed-out characteristics, internal haze, brittleness, light resistance, and wet heat resistance. It has been found that when this optical film is used, a polarizing plate that has high light resistance and wet heat resistance, suppresses front contrast unevenness of the liquid crystal display device, and improves the viewing angle can be obtained.

That is, the said subject which concerns on this invention is solved by the following means.
1. An optical film comprising a thermoplastic resin and a compound represented by the following general formula (1).

(In General Formula (1), X ₁ represents an oxygen atom or a sulfur atom, Y ₁ represents an oxygen atom, a sulfur atom, a nitrogen atom, or NR ₄₁ , and Z ₁ represents an oxygen atom, a nitrogen atom, or a sulfur atom. R ₁₁ , R ₂₁ and R ₃₁ represent a substituent, and examples of the substituent represented by R ₁₁ include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an amino group, and an alkylamino group. , An arylamino group, an alkylthio group, an arylthio group, or a heterocyclic group, and the substituents represented by R ₂₁ and R ₃₁ are an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, and an aryloxy group, respectively. Acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, acylamino group, sulfonyl group, sulfonyloxy Group, an amino group, the substituent is .R ₄₁ to an alkylthio group, or a halogen atom represented by .R ₄₁ represents a hydrogen atom or a substituent, an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, Represents an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an alkylthio group, or a halogen atom, k1 represents an integer of 1 to 5, m1 represents an integer of 0 to 4, and n1 represents Represents an integer of 0 to 4. The broken line represents a single bond or a double bond.)
2. 2. The optical film according to item 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

(In General Formula (2), X ₂ represents an oxygen atom or a sulfur atom, Y ₂ represents an oxygen atom, a sulfur atom, a nitrogen atom or NR ₄₂ , and Z ₂ represents an oxygen atom, a nitrogen atom or a sulfur atom. R ₁₂ and R ₂₂ represent a substituent, R ₄₂ represents a hydrogen atom or a substituent, and the substituents R ₁₂ , R ₂₂ and R ₄₂ are the same as R ₁₁ , R ₂₁ and R ₄₁ in the general formula (1). (M2 represents an integer of 0 to 4. n2 represents an integer of 0 to 4. The broken line represents a single bond or a double bond.)
3. 3. The optical film according to item 2, wherein the compound represented by the general formula (2) is a compound represented by the following general formula (3).

(In the general formula (3), R ₁₃ and R ₂₃ represent a substituent. The substituents R ₁₃ and R ₂₃ have the same meanings as R ₁₁ and R ₂₁ in the general formula (1), respectively. M3 represents an integer of 0 to 4.)

(In the general formula (4), R ₁₄ represents a substituent. The substituent R ₁₄ has the same meaning as R ₁₁ in the general formula (1). K4 represents an integer of 1 to 5.)
5. The optical film according to any one of Items 1 to 4, wherein the thermoplastic resin contains a cellulose ester.
6). 6. The optical film as described in 5 above, wherein the cellulose ester satisfies both of the following formulas (a) and (b).

Formula (a) 1.5 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
(In the formula, X represents the degree of substitution of the acetyl group. Y represents the degree of substitution of the propionyl group or butyryl group or the total degree of substitution thereof.)
7). The optical film according to any one of items 1 to 6, wherein the film thickness of the optical film is in a range of 20 to 60 μm.
In an environment of 8.23 ° C. and 55% RH, the retardation value Ro in the in-plane direction represented by the following formula is in the range of 20 to 150 nm at a measurement wavelength of 590 nm, and the retardation value in the thickness direction. The optical film according to any one of items 1 to 7, wherein Rth is in a range of 70 to 350 nm.

Formula _{(I) Ro = (n x} -n y) × d
Formula (II) Rth = {(n _x + n _y ) / 2−n _z } × d
(N _x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the optical film, n _y is in the plane direction of the optical film, the refractive index in the direction y perpendicular to the direction x , _Nz represents the refractive index in the thickness direction z of the optical film, and d (nm) represents the thickness of the optical film.)
9. A polarizing plate, wherein the optical film according to any one of items 1 to 8 is provided on at least one surface of a polarizer.
10. 10. A liquid crystal display device, wherein the polarizing plate according to item 9 is provided on at least one surface of a liquid crystal cell.

By the above means of the present invention, it is possible to provide an optical film having high retardation expression, bleed-out suppression, low internal haze, excellent brittleness, and high light resistance and moisture-heat resistance. Further, the polarizing plate provided with the optical film can have good light resistance and moisture and heat resistance, and by using the polarizing plate, a liquid crystal display device excellent in front contrast unevenness and viewing angle deterioration over time is provided. can do.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

The compound represented by the general formula (1) according to the present invention forms a hydrogen bond with a thermoplastic resin by introducing a substituent with —OCO— as a linking group into a phenyl group substituted at a specific position, By orienting, it is considered that the optical film containing the thermoplastic resin is given a high retardation. Further, since the above compound is highly compatible with the thermoplastic resin, it is considered that the internal haze deterioration and bleed-out are suppressed, the brittleness is excellent, and light resistance and wet heat resistance are improved.

Schematic diagram showing a state in which glycerin is dropped on a slide glass Schematic diagram showing the state of a sample film placed on glycerin Schematic diagram showing the state in which glycerin is dropped on the sample film Schematic diagram showing a state where a cover glass is placed on glycerin

The optical film of the present invention is an optical film containing a thermoplastic resin, and contains the compound represented by the general formula (1).

Here, "thermoplastic resin" refers to a resin that becomes soft when heated to the glass transition temperature or melting point and can be molded into the desired shape.

This feature is a technical feature common to the inventions according to claims 1 to 10.

As an embodiment of the present invention, it is preferable that the compound represented by the general formula (1) is a compound represented by the general formula (2) from the viewpoint of manifesting the effects of the present invention. The compound represented by the general formula (2) is preferably represented by the general formula (3), and the compound represented by the general formula (3) is represented by the general formula (4). It is preferable that the compound represented by the present invention provides an optical film that has high retardation expression, bleed-out is suppressed, internal haze is low, brittleness is excellent, and light resistance and moisture and heat resistance are high. .

Further, the fact that the thermoplastic resin is a cellulose ester is compatible with the compounds represented by the general formula (1), the general formula (2), the general formula (3), and the general formula (4). It is preferable for obtaining an optical film that is excellent, has high retardation development properties, and has high light resistance and heat and moisture resistance.

Moreover, it is said that the said cellulose ester is a cellulose ester which has the specific acyl group substitution degree which satisfy | fills said Formula (a) and (b), said General Formula (1), said General Formula (2), and said General Formula (3) Excellent compatibility with the compound represented by the general formula (4), high retardation expression, bleed-out is suppressed, internal haze is low, brittleness is excellent, and light resistance It is preferable for obtaining an optical film having high moisture and heat resistance.

The film thickness of the optical film is preferably in the range of 20 to 60 μm from the viewpoint of suppressing bleeding out and being excellent in brittleness.

Furthermore, the optical film has an in-plane retardation value Ro in the range of 20 to 150 nm represented by the following formula at a measurement wavelength of 590 nm under an environment of 23 ° C. and 55% RH. The retardation value Rth is preferably in the range of 70 to 350 nm for providing an optical film with good visibility.

The optical film of the present invention is suitably provided in a polarizing plate and a liquid crystal display device, a polarizing plate having good light resistance and wet heat resistance, and liquid crystal with reduced front contrast unevenness and humidity dependency of a viewing angle. A display device is provided.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

<Optical film of the present invention>
The optical film of the present invention contains a thermoplastic resin, a compound represented by the general formula (1), and other optional components.

<Thermoplastic resin>
Thermoplastic resins include cellulose ester resins, polycarbonate resins, polystyrene resins, polysulfone resins, polyester resins, polyarylate resins, (meth) acrylic resins, olefin resins (eg, norbornene resins, cyclic olefins). Resin, cyclic conjugated diene resin, vinyl alicyclic hydrocarbon resin) and the like. Among these, cellulose ester resins, (meth) acrylic resins, polycarbonate resins, and cyclic olefin resins are preferable, and cellulose ester resins are most preferable.

<Cellulose ester>
The cellulose ester contained in the optical film of the present invention is not particularly limited, but is preferably a linear or branched carboxylic acid ester having about 2 to 22 carbon atoms. The carboxylic acid constituting the ester may form a ring or an aromatic carboxylic acid. The carboxylic acid constituting the ester may have a substituent. The carboxylic acid constituting the ester is particularly preferably a lower fatty acid having 6 or less carbon atoms.

Specific examples of preferred cellulose esters include cellulose acetate; cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, and the like. Mixture of cellulose having propionate group or butyrate group in addition to acetyl group Examples include fatty acid esters.

It is more preferable that the cellulose ester satisfies both the following formulas (a) and (b). In the formula, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or butyryl group, or the degree of substitution of a mixture thereof. The degree of substitution of the acyl group can be measured according to ASTM-D817-96.

Formula (a) 1.5 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
The cellulose ester is more preferably cellulose acetate (Y = 0) and cellulose acetate propionate (Y; propionyl group, Y> 0). Cellulose acetate propionate satisfies 1.0 ≦ X ≦ 2.4, preferably 0.1 ≦ Y ≦ 1.5, and 2.0 ≦ X + Y ≦ 2.5. The cellulose acetate is preferably 1.5 ≦ X ≦ 2.5, more preferably 2.0 ≦ X ≦ 2.5. The cellulose acetate most preferably used is cellulose diacetate (DAC) with 2.0 ≦ X ≦ 2.5.

By using the above-mentioned cellulose acetate or cellulose acetate propionate, an optical film excellent in retardation, mechanical strength and environmental fluctuation can be obtained.

In order to obtain desired optical characteristics, cellulose acetates having different degrees of substitution may be mixed and used. The mixing ratio of different cellulose acetates is not particularly limited, and may be in the range of 10:90 to 90:10 (mass ratio).

The number average molecular weight of the cellulose ester is preferably in the range of 6 × 10 ⁴ to 3 × 10 ⁵ , and more preferably in the range of 7 × 10 ⁴ to 2 × 10 ⁵ . It is because the mechanical strength of the obtained film becomes high. The weight average molecular weight Mw and the number average molecular weight Mn of the cellulose ester can be measured using gel permeation chromatography (GPC). An example of measurement conditions is as follows, but is not limited to this, and an equivalent measurement method can be used.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three products manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Co., Ltd.) Mw = 1000000-500 13 calibration curves are used. Thirteen samples are used at approximately equal intervals.

The raw material cellulose of the cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

Cellulose esters such as cellulose acetate and cellulose acetate propionate can be produced by known methods. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

<Compound represented by the general formula (1)>
The optical film of the present invention contains a compound represented by the general formula (1). The compound represented by general formula (1) may be a compound represented by general formula (2), general formula (3), and general formula (4).

In the general formula (1), R ₁₁ represents a substituent. The substituent is preferably the following substituent from the viewpoint of the solubility of the compound and the interaction with cellulose (compatibility and retardation development).

Examples of the substituent represented by R ₁₁ include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc. ), Cycloalkyl group (eg, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), alkyloxy group (eg, alkoxy group, t-butoxy group, etc.) ), An aryloxy group (eg, phenoxy group, naphthoxy group, etc.), an alkylamino group (eg, ethylamino group), an arylamino group (eg, phenylamino group), an alkylthio group (eg, methylthio group, 2- Ethylhexylthio group, etc.), arylthio group (eg, phenylthio group, etc.), hetero Ring group (eg, pyridyl group, pyrimidyl group, oxazolyl group, thiazolyl group, oxadiazolyl group, thiadiazolyl group, imidazolyl group, etc.), amino group (eg, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino) Group, 2-ethylhexylamino group, dodecylamino group, etc.).

The substituent represented by R ₁₁ is further an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.) , A cycloalkyl group (eg, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, etc.), an aryl group (eg, phenyl group, naphthyl group, etc.), a heterocyclic group (eg, pyridyl group, pyrimidyl group, oxazolyl group, Thiazolyl group, oxadiazolyl group, thiadiazolyl group, imidazolyl group, etc.), acylamino group (eg, acetylamino group, benzoylamino group, etc.), alkylthio group (eg, methylthio group, ethylthio group, etc.), arylthio group (eg, phenylthio group, Naphthylthio groups, etc.), alkenyl groups (eg For example, vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, styryl group, etc. ), Halogen atoms (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkynyl groups (for example, propargyl group, etc.), alkylsulfonyl groups (for example, methylsulfonyl group, ethylsulfonyl group, etc.), arylsulfonyl groups (Eg, phenylsulfonyl group, naphthylsulfonyl group, etc.), alkylsulfinyl group (eg, methylsulfinyl group, etc.), arylsulfinyl group (eg, phenylsulfinyl group, etc.), phosphono group, acyl group (eg, acetyl group, pivaloyl group) Benzoyl group, etc.), carbamoyl group (for example, amino Bonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butyl) Aminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide group (for example, methanesulfone) Amide group, benzenesulfonamide group, etc.), cyano group, alkyloxy group (for example, methoxy group, ethoxy group, propoxy group, etc.), aryloxy (Eg, phenoxy group, naphthyloxy group, etc.), siloxy group, acyloxy group (eg, acetyloxy group, benzoyloxy group, etc.), sulfonic acid group or salt thereof, aminocarbonyloxy group, amino group (eg, amino group, Ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group) 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2- Pyridylua Minoleido group etc.), alkoxycarbonylamino group (eg methoxycarbonylamino group, phenoxycarbonylamino group etc.), alkoxycarbonyl group (eg methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl etc.), aryloxycarbonyl group (eg Phenoxycarbonyl group etc.), carbamate group (eg methyl carbamate group, phenyl carbamate group), alkyloxyphenyl group (eg methoxyphenyl group etc.), acyloxyphenyl group (eg acetyloxyphenyl group etc.), thioureido group, carboxy A group, a salt of a carboxylic acid, a hydroxy group, a mercapto group, a nitro group, or the like may be substituted, and adjacent substituents may be bonded to form a ring.

Preferred examples of R ₁₁ include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an amino group, an alkylamino group, an arylamino group, and an alkylthio group; an alkyl group, a cycloalkyl group, and an alkyl group An oxy group, an aryl group, an aryloxy group and an alkylthio group are preferred; an alkyl group, an alkyloxy group, an aryl group and an aryloxy group are more preferred; an alkyl group and an alkyloxy group are particularly preferred, and an alkyl group is most preferred. When R ₁₁ is an alkyl group, an alkyl group having 1 to 8 carbon atoms is preferable. 1-4 alkyl groups are more preferred. By using R ₁₁ as these substituents, the compatibility of the compound is improved, the internal haze is low, and an optical film with high retardation is obtained.

In the general formula (1), R ₂₁ and R ₃₁ represent a substituent. Examples of the substituent represented by R ₂₁ and R ₃₁ include alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoro group). Methyl group etc.), cycloalkyl group (eg cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group etc.), aryl group (eg phenyl group, naphthyl group etc.), heterocyclic group (eg pyridyl group, pyrimidyl group) Oxazolyl group, thiazolyl group, oxadiazolyl group, thiadiazolyl group, imidazolyl group etc.), acylamino group (eg acetylamino group, benzoylamino group etc.), alkylthio group (eg methylthio group, ethylthio group etc.), arylthio group (eg , Phenylthio group, naphthylthio group, etc.), c Gen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), sulfonyl group (alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, etc.)), arylsulfonyl group (for example, phenylsulfonyl group, naphthylsulfonyl) Group)), acyl group (for example, acetyl group, pivaloyl group, benzoyl group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, Phenylaminocarbonyl group etc.), alkyloxy group (eg methoxy group, ethoxy group, propoxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), amino group (eg amino group, ethylamino group) , Jimechi Ruamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl etc.), aryloxycarbonyl group (eg, phenoxy) Carbonyl group etc.) and alkylthio groups (eg methylthio group, 2-ethylhexylthio group etc.).

A plurality of substituents represented by R ₂₁ and R ₃₁ in the general formula (1) may be further substituted with the same groups, and adjacent substituents may be bonded to form a ring.

Preferred examples of R ₂₁ include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an alkylthio group, and a halogen atom; Group, cycloalkyl group, alkyloxy group, aryl group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group and halogen atom are more preferred; alkyl group, alkyloxy group, acyl group and alkoxycarbonyl group are particularly preferred preferable. By using R ₂₁ as these substituents, the compatibility of the compound is improved, the internal haze is low, and the bleed-out is suppressed, resulting in a high retardation optical film.

Preferable examples of R ₃₁ include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an acyl group, an acyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an alkylthio group, and a halogen atom. Preferred: alkyl group, cycloalkyl group, alkyloxy group, aryl group, aryloxy group, acyl group, acyloxy group, alkoxycarbonyl group, aryloxycarbonyl group, amino group, alkylthio group, halogen atom are preferred; alkyl group, alkyl group An oxy group, an aryl group, an aryloxy group, an acyl group, an acyloxy group, an alkoxycarbonyl group, and an aryloxycarbonyl group are particularly preferable. By using R ₃₁ as these substituents, the compatibility of the compound is improved, the internal haze is low, and the bleed-out is suppressed, resulting in a high retardation optical film.

R ₄₁ represents a hydrogen atom or a substituent, and examples of the substituent represented by R ₄₁ include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an acyl group, an alkoxycarbonyl group, and an aryloxycarbonyl. Group, amino group, alkylthio group, and halogen atom.

Preferred examples of R ₄₁ are preferably a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, and an aryloxycarbonyl group; a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, and an acyl group Are more preferable, and an alkyl group, an aryl group, and an acyl group are particularly preferable. By introducing groups such as these, the compatibility of the compound is improved, the internal haze is low, and the bleed-out is suppressed, resulting in a high retardation optical film.

In the general formula (1), the integer represented by k1 is preferably in the range of 1 to 4, more preferably in the range of 1 to 3, and particularly preferably 1, from the viewpoints of phase difference development and compatibility.

In the general formula (1), the substitution position of —OCO— is preferably substituted at the 3-position, 4-position, and 5-position when the binding site with the benzoxazinone skeleton is the 1-position. More preferably, it is substituted. High retardation is expressed by substituting at these positions.

In the general formula (1), the integer represented by m1 is preferably in the range of 0 to 4, more preferably in the range of 0 to 3, and particularly preferably 0 from the viewpoint of retardation development.

The integer represented by n1 in the general formula (1) is preferably in the range of 0 to 4, more preferably in the range of 0 to 3, particularly preferably 0 from the viewpoint of compatibility.

X ₁ in the general formula (1) is preferably an oxygen atom from the viewpoint of light resistance.

Y1 in the general formula (1) is preferably an oxygen atom, a nitrogen atom or NR ₄₁ from the viewpoint of light resistance, more preferably an oxygen atom or a nitrogen atom, and particularly preferably an oxygen atom.

Z ₁ in the general formula (1) is preferably an oxygen atom or a nitrogen atom, and particularly preferably a nitrogen atom, from the viewpoint of light resistance.

X ₂ , Y ₂ , Z ₂ , R ₁₂ , R ₂₂ , R ₄₂ , k 2, and m 2 in the general formula (2) are X ₁ , Y ₁ , Z ₁ , R ₁₁ , R ₂₁ in the general formula (1). , R ₄₁ , k 1, and m 1 are synonymous with each other.

R < ₁₃ >, R < ₂₃ >, k3, and m3 in General formula (3) are synonymous with R < ₁₁ >, R < ₂₁ >, k1, and m1 in General formula (1), respectively.

R ₁₄ and k4 in the general formula (4) have the same meanings as R ₁₁ and k1 in the general formula (1), respectively.

Specific examples of the compounds represented by the general formula (1), the general formula (2), the general formula (3), and the general formula (4) are shown below, but the present invention is not limited to the following specific examples. It is not limited.

The optical film of the present invention contains a thermoplastic resin and a compound represented by the general formula (1). In order to obtain a desired retardation, the compound represented by the general formula (1) is contained in the thermoplastic resin. It is preferable that it is added to. Addition means being dissolved or dispersed in the thermoplastic resin. A desired retardation cannot be obtained only by applying the compound represented by the general formula (1) only to the surface of the optical film.

The optical film of the present invention contains the compound represented by the general formula (1) in a range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the thermoplastic resin in order to obtain a desired retardation. It is preferably 1 to 15 parts by mass, more preferably 1.5 to 10 parts by mass, and particularly preferably 2 to 6 parts by mass. Within this range, sufficient retardation is imparted to the optical film of the present invention, and internal haze, compatibility, and bleed-out characteristics are improved.

In the present invention, the compound represented by the general formula (1) has a thickness direction retardation value Rth of _{550 nm} (550 _nm ) of an optical film containing 3 parts by mass of the compound of the general formula (1) with respect to 100 parts by mass of the thermoplastic resin. The retardation value in the thickness direction measured in step 1) is preferably 1.1 times or more, more preferably in the range of 1.2 times to 10 times compared to the unadded thermoplastic resin film. A range of 3 to 4 times is particularly preferable. By adding a compound in the above range, an optical film having excellent retardation can be provided.

The optical film of this invention should just contain at least 1 or more types of compounds represented by the said General formula (1), and can also give retardation by using compounds other than the said General formula (1) together. it can.

<Synthesis of Compound Represented by General Formula (1)>
The compound represented by the general formula (1) can be synthesized by a general method. Synthesis examples of exemplary compounds are described below.

(Synthesis of Exemplary Compound A-022)

In a 2 L eggplant flask, 56 g of 4-hydroxybenzoic acid and 800 ml of 1N NaOH aqueous solution were added, stirred and dissolved at 40 ° C., and 50 g of acetic anhydride was added dropwise. After stirring for 1 hour, the mixture was cooled with water and 30 ml of acetic acid was added. After stirring for 1 hour, 54.5 g of intermediate A was obtained by filtering, washing with water and drying.

In a 100 ml eggplant flask, 5.0 g of intermediate A, 3.0 ml of thionyl chloride and 0.1 ml of DMF were added and heated at 80 ° C. for 3 hours. The solvent and thionyl chloride were distilled off under reduced pressure to obtain 5.6 g of Intermediate B.

After adding 50 ml of pyridine and 4.5 g of isatoic anhydride to a 200 ml eggplant flask and heating to 50 ° C., 5.6 g of intermediate B was added dropwise. After completion of dropping, the external temperature was raised to 120 ° C. After 2 hours, the mixture was cooled to room temperature, 100 ml of water was added, and the mixture was stirred for 1 hour. 6.4 g of a crude product was obtained by drying after filtration and washing with methanol. The crude product was purified by column chromatography (developing solvent: toluene) to obtain 3.8 g of Exemplified Compound A-022. The obtained exemplary compound A-022 was identified by NMR and Mass spectrum.

(Synthesis of Exemplary Compound A-073)

In a 500 ml eggplant flask, 42.0 g of salicylamide, 100 ml of xylene and 5 ml of pyridine were added and heated at 150 ° C. to reflux. Intermediate B66.9g was dripped at this reaction liquid over 1 hour. After completion of the dropwise addition, the mixture was heated to reflux for 7 hours, cooled to room temperature, and the solvent was distilled off under reduced pressure. The residue was purified by column chromatography (developing solvent: toluene / acetone = 5/1) to obtain 8.7 g of Exemplified Compound A-073. The obtained exemplary compound A-073 was identified by NMR and Mass spectrum.

(Synthesis of Exemplary Compound A-115)

10 g of methyl anthranilate and 30 ml of pyridine were dissolved and ice-cooled. 14 g of Intermediate B was added dropwise to this solution. 200 ml of water was added to the reaction solution and stirred for 2 hours. The precipitated solid was filtered and washed with water to obtain 13.2 g of Intermediate C.

Intermediate C 10.4 g, phosphorus pentasulfide 18 g and dry pyridine 150 ml were added, heated to 140 ° C. and heated to reflux for 18 hours. After heating, the reaction solution was poured into ice water and stirred. The precipitated solid was filtered, dissolved in dichloromethane, and dried using anhydrous magnesium sulfate. Dichloromethane was distilled off under reduced pressure and recrystallized from dichloromethane / ethanol to obtain 6.9 g of Exemplified Compound A-115. The obtained exemplary compound A-115 was identified by NMR and Mass spectrum.

(Synthesis of Exemplary Compound A-124)

To a 200 ml eggplant flask, 5.6 g of 4-cyanophenol and 80 ml of 1N NaOH aqueous solution were added and stirred at 40 ° C., and 5.5 g of acetic anhydride was added dropwise. After stirring for 1 hour, it was cooled with water and 3 ml of acetic acid was added. After stirring for 1 hour, 4.7 g of intermediate D was obtained by filtering, washing with water and drying.

In a 200 ml eggplant flask, 4.7 g of intermediate D, 9.8 g of methyl thiosalicylate, 6.5 g of triethylamine, and 30 ml of toluene were added, and the mixture was nitrogenated and heated to reflux for 25 hours. After completion of the heating, the solvent was distilled off under reduced pressure. By purification by column chromatography (developing solvent: hexane / ethyl acetate = 5/1), 3.2 g of Exemplified Compound A-124 was obtained. The obtained exemplary compound A-124 was identified by NMR and Mass spectrum.

(Synthesis of Exemplary Compound A-133)

6.2 g of Intermediate C, Lawesson's reagent 40 g, and 100 ml of toluene were added to a 300 ml eggplant flask and heated to reflux for 10 hours. After cooling to room temperature, the solid was filtered, and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography (developing solvent: heptane / ethyl acetate = 9/1) to obtain 4.3 g of Intermediate E.

In a 200 ml eggplant flask, 4.3 g of intermediate E, 50 ml of acetone and 10 g of acetic anhydride were added and heated to reflux for 4 hours. After cooling, 50 ml of methanol was added and stirred for 1 hour. The precipitated solid was filtered and washed with methanol to obtain 3.2 g of Compound A-133. The obtained exemplary compound A-133 was confirmed by NMR and mass spectrum.

(Synthesis of Exemplary Compound A-146)

To the 1 L eggplant flask, 40 g of anthranilic acid, 32.0 g of triethylamine, and 100 ml of acetone were added and stirred under water cooling. To this reaction solution, 58.0 g of Intermediate B was added dropwise over 1 hour and then stirred for 3 hours. The reaction mixture was concentrated under reduced pressure, 51.8 g of 2-ethylhexylamine and 1 ml of acetonitrile were added, and the mixture was stirred at room temperature. 55 g of PCl ₃ was added to the reaction solution, and the mixture was heated to 50 ° C. and stirred for 20 hours. After completion of heating, the mixture was cooled to room temperature, and 500 ml of ethyl acetate was added. 1N hydrochloric acid, 5% NaHCO ₃ aqueous solution, and pure water were separated in this order, and the organic layer was concentrated under reduced pressure. The residue was purified by column chromatography (developing solvent: toluene / ethyl acetate = 5/1) to obtain 12.5 g of exemplary compound A-146. The obtained exemplary compound A-146 was identified by NMR and Mass spectrum.

Other compounds represented by the general formula (1) can also be synthesized with reference to the disclosure of the present specification and known techniques.

The optical film of the present invention may contain other optional components in addition to the thermoplastic resin and the compound represented by the general formula (1). Examples of optional components include wavelength dispersion control agents, sugar esters, plasticizers, ultraviolet absorbers, antioxidants, and fine particles.

<Chromatic dispersion control agent>
The optical film of the present invention can also contain a wavelength dispersion controlling agent. A “wavelength dispersion controlling agent” is a compound that adjusts the wavelength dependence of retardation of an optical film. Preferable examples of the wavelength dispersion controlling agent include discotic compounds described in JP-A Nos. 2001-166144 and 2003-344655, and compounds described in JP-A 2010-163482.

The wavelength dispersion controlling agent preferably has an absorption maximum in the wavelength range of 250 nm to 400 nm or in the wavelength range of 270 nm to 380 nm.

The wavelength dispersion controlling agent can be used alone or in combination of two or more. The addition amount of the wavelength dispersion control agent is preferably within a range of 1.0 to 20% by mass, more preferably within a range of 1.5 to 15% by mass, with respect to 100 parts by mass of the thermoplastic resin. The range of 10% by mass is most preferable. The wavelength dispersion control agent can be added by dissolving the wavelength dispersion control agent in an organic solvent such as alcohol, methylene chloride, or dioxolane, and then adding it to the thermoplastic resin solution (dope) or directly in the dope composition. It may be added.

The wavelength dispersion control agent may be added in advance to the thermoplastic resin mixed solution, or may be added in any step from the production of the thermoplastic resin dope to the casting. In the latter case, a solution in which a wavelength dispersion controlling agent and a small amount of a thermoplastic resin are dissolved is added in-line to a dope in which a thermoplastic resin is dissolved in a solvent and mixed. The mixing is preferably performed with an in-line mixer such as a static mixer (manufactured by Toray Engineering) or SWJ (Toray static type in-pipe mixer Hi-Mixer).

A matting agent may be added together with the wavelength dispersion controlling agent, or additives such as a retardation controlling agent, a plasticizer, a deterioration preventing agent and a peeling accelerator may be added.

When using an in-line mixer, it is preferable to concentrate and dissolve under high pressure; the pressurized container only needs to be able to withstand a predetermined pressure and to be heated and stirred under pressure. Instruments such as a pressure gauge and a thermometer are appropriately disposed in the pressurized container. The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating.

Heating is preferably performed from the outside of the container. For example, a jacket type heater is preferable because of easy temperature control. The heating temperature with the addition of the solvent is preferably a temperature not lower than the boiling point of the solvent used and in a range where the solvent does not boil, for example, in the range of 30 to 150 ° C. Adjust the pressure so that the solvent does not boil at the set temperature. After dissolution, it is taken out from the container while cooling, or extracted from the container with a pump or the like and cooled with a heat exchanger or the like, and used for film formation. The cooling temperature at this time may be cooled to room temperature, but it is more preferable to cool to a temperature 5 to 10 ° C. lower than the boiling point and perform casting at that temperature because the dope viscosity can be reduced.

<Sugar ester>
The optical film of the present invention preferably contains a sugar ester other than cellulose ester. The sugar ester is a compound containing at least one of a furanose structure or a pyranose structure. The sugar ester may be a monosaccharide or a polysaccharide having 2 to 12 sugar structures linked together. The sugar ester is preferably a compound in which at least one OH group of the sugar structure is esterified. The esterification rate of the sugar ester is preferably 70% or more of the OH groups present in the pyranose structure or furanose structure.

Examples of sugars constituting the sugar ester include glucose, galactose, mannose, fructose, xylose, or arabinose, lactose, sucrose, nystose, 1F-fructosylnystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, Cellotriose, maltotriose, raffinose or kestose are included. Furthermore, examples of the sugar constituting the sugar ester include gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like. Of course, the sugar is not limited to these. The sugar structure constituting the sugar ester preferably contains both a pyranose structure and a furanose structure.

Preferred examples of the sugar constituting the sugar ester include sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, and more preferably sucrose.

In the sugar ester, all or part of the OH group in the pyranose structure or furanose structure is esterified. The monocarboxylic acid for esterification is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. The carboxylic acid used may be one type or a mixture of two or more types.

Examples of preferred aliphatic monocarboxylic acids constituting the esters of sugar esters include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl- Hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicin Examples thereof include saturated fatty acids such as acid and lacteric acid, and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, and octenoic acid.

Examples of preferable alicyclic monocarboxylic acid constituting the ester of a sugar ester include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, or derivatives thereof.

Examples of preferred aromatic monocarboxylic acids constituting the esters of sugar esters include aromatic monocarboxylic acids, cinnamates, and benzyls in which alkyl groups and alkoxy groups are introduced into the benzene ring of benzoic acids such as benzoic acid and toluic acid. Aromatic monocarboxylic acids having two or more benzene rings such as acid, biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, or derivatives thereof are included. More specifically, xylic acid, hemelitic acid, mesitylene acid, prenicylic acid, γ-isoduric acid, duryl acid, mesitonic acid, α-isoduryl acid, cumic acid, α-toluic acid, hydroatropic acid, atropaic acid, hydrocinnamic Acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid, creosote acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyrocatechuic acid, β-resorcylic acid, vanillic acid , Isovanillic acid, veratrumic acid, o-veratormic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratormic acid, o-homoveratormic acid, phthalonic acid, p-coumaric acid; especially benzoic acid preferable.

Oligosaccharide esters can be used as sugar esters in the present invention. Oligosaccharides are produced by allowing an enzyme such as amylase to act on starch, sucrose, etc. Examples of preferred oligosaccharides include maltooligosaccharides, isomalto-oligosaccharides, fructooligosaccharides, galactooligosaccharides, and xylo-oligosaccharides. .

The sugar ester is a compound obtained by condensing 1 or more and 12 or less of at least one of a pyranose structure or a furanose structure represented by the following general formula (A). R ₁₁ to R ₁₅ and R ₂₁ to R ₂₅ in the general formula (A) are an acyl group having 2 to 22 carbon atoms or a hydrogen atom, m and n are each an integer of 0 to 12, and m + n is an integer of 1 to 12 It is.

R ₁₁ to R ₁₅ and R ₂₁ to R ₂₅ are preferably a benzoyl group or a hydrogen atom. The benzoyl group may have a substituent R ₂₆ (p is 0 to 5), and examples thereof include an alkyl group, an alkenyl group, an alkoxyl group, and a phenyl group. Further, these alkyl group, alkenyl group, and phenyl group are It may have a substituent. Oligosaccharide esters can also be produced in the same manner as other sugar esters.

Specific examples of the sugar ester used in the present invention include compounds described in paragraphs [0130] to [0137] of JP2012-230154A and paragraphs [0077] to [0078] of JP2012-230282A. However, the present invention is not limited to this.

The optical film of the present invention preferably contains 0.5 to 30% by mass of the sugar ester, particularly 5%, in order to suppress the fluctuation of the retardation value and stabilize the display quality. It is preferable to contain ~ 30% by mass.

<Plasticizer>
The optical film of the present invention may contain a plasticizer. The plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or a polyester plasticizer. Agent, acrylic plasticizer and the like. When two or more kinds of plasticizers are included in the optical film of the present invention, at least one is preferably a polyhydric alcohol ester plasticizer.

(Polyhydric ester plasticizer)
The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. A divalent to 20-valent aliphatic polyhydric alcohol ester is preferred.

The polyhydric alcohol constituting the polyhydric alcohol ester plasticizer is represented by the following general formula (a).

Formula (a) Ra- (OH) _n
Here, Ra represents an n-valent organic group, n represents a positive integer of 2 or more, and an OH group represents an alcoholic or phenolic hydroxy group.

Examples of preferred polyhydric alcohols constituting the polyhydric alcohol ester plasticizer include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, Dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1 , 6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, etc. It is not particularly limited. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

Examples of monocarboxylic acids constituting the polyhydric alcohol ester plasticizer are not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids and the like can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

Examples of preferable monocarboxylic acid include, but are not limited to, the following.

Examples of the aliphatic monocarboxylic acid include fatty acids having a straight chain or a side chain having 1 to 32 carbon atoms. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

Examples of preferable alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, or derivatives thereof.

Examples of preferred aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, Aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof are included. Benzoic acid is particularly preferable.

The carboxylic acid constituting the ester of the polyhydric alcohol ester plasticizer may be one kind or a combination of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

The molecular weight of the polyhydric alcohol ester plasticizer is not particularly limited, but is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with thermoplastic resins.

(Glycolate plasticizer)
The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates are preferably used. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl Glycolate, and the like are included.

(Phthalate ester plasticizer)
Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate and the like.

(Citrate ester plasticizer)
Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate and the like.

(Fatty acid ester plasticizer)
Examples of the fatty acid ester plasticizer include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate and the like.

(Phosphate ester plasticizer)
Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

(Polycarboxylic acid ester plasticizer)
The polyvalent carboxylic acid ester plasticizer is an esterified product of a divalent or higher, preferably divalent to valent 20 polyvalent carboxylic acid and an alcohol. The aliphatic polyvalent carboxylic acid is preferably divalent to 20-valent, and in the case of an aromatic polyvalent carboxylic acid or alicyclic polyvalent carboxylic acid, it is preferably trivalent to 20-valent.

The polyvalent carboxylic acid is represented by the following general formula (b).

Formula (b) Rb (COOH) _m (OH) _n
(However, Rb represents an (m + n) -valent organic group, m represents a positive integer of 2 or more, n represents an integer of 0 or more, a COOH group represents a carboxy group, and an OH group represents an alcoholic or phenolic hydroxy group.)
Examples of preferable polyvalent carboxylic acids include trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, sulphate Examples thereof include, but are not limited to, aliphatic polyvalent carboxylic acids such as acid, fumaric acid, maleic acid, and tetrahydrophthalic acid, and oxypolyvalent carboxylic acids such as tartaric acid, tartronic acid, malic acid, and citric acid. In particular, use of an oxypolycarboxylic acid is preferable because the retention of the plasticizer (not to be volatilized from the optical film) is improved.

The alcohol constituting the ester of the polycarboxylic acid ester plasticizer may be a known alcohol or phenol and is not particularly limited. For example, it is an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms. In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.

The alcohol constituting the ester of the polycarboxylic acid ester plasticizer may be one kind or a mixture of two or more kinds.

When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic hydroxy group or phenolic hydroxy group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. The monocarboxylic acid is preferably an aliphatic monocarboxylic acid, but is not limited thereto.

The aliphatic monocarboxylic acid is preferably a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms. Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

Examples of preferable alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. The aromatic monocarboxylic acid which has, or derivatives thereof can be mentioned.

It is particularly preferable that the carboxylic acid that esterifies the alcoholic hydroxy group or phenolic hydroxy group of the oxypolycarboxylic acid is acetic acid, propionic acid, or benzoic acid.

The molecular weight of the polycarboxylic acid ester plasticizer is not particularly limited, but is preferably in the range of 300 to 1000, more preferably in the range of 350 to 750. The larger one is preferable in terms of improving the retentivity of the plasticizer; the smaller one is preferable in terms of moisture permeability and compatibility with the cellulose ester.

The acid value of the polycarboxylic acid ester plasticizer is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value in the above range is preferable because the environmental fluctuation of the retardation is also suppressed. The acid value refers to the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxy group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

Particularly preferred examples of the polycarboxylic acid ester plasticizer include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, Acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like can be mentioned, but not limited thereto.

(Polyester plasticizer)
The polyester plasticizer is, for example, a polyester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule. The polyester plasticizer is, for example, an aromatic terminal ester plasticizer represented by the following general formula (c).

Formula (c) B- (GA) _n -GB
(Wherein B is a benzene monocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
The polyester plasticizer represented by the general formula (c) includes a benzene monocarboxylic acid residue represented by B, an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue represented by G, and an alkylene represented by A. A dicarboxylic acid residue or an aryldicarboxylic acid residue. The polyester plasticizer can be obtained by the same reaction as a normal polyester plasticizer.

Examples of benzene monocarboxylic acid components of polyester plasticizers include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, normal propyl benzoic acid, aminobenzoic acid , Acetoxybenzoic acid, and the like, which may be one or a combination of two or more thereof.

Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester plasticizer include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3- Methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2- Chill-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, include 1,12-octadecanediol like. These glycols are used as one kind or a mixture of two or more kinds. In particular, alkylene glycols having 2 to 12 carbon atoms are particularly preferable because of excellent compatibility with cellulose esters.

Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the polyester plasticizer include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. It can be used as a mixture of seeds or more.

Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the polyester plasticizer include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid and the like. These are each used as a mixture of one or more. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and the like.

The number average molecular weight of the polyester plasticizer is preferably in the range of 300 to 1500, more preferably in the range of 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxy group value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxy group value is 15 mgKOH / g or less.

(Acrylic plasticizer)
The (meth) acrylic polymer as an acrylic plasticizer includes at least an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxy group in the molecule, and ethylene having a hydroxy group without an aromatic ring in the molecule. It may be a polymer X having a weight average molecular weight of 3000 or more and 30000 or less obtained by copolymerization with the unsaturated unsaturated monomer Xb.

Alternatively, the (meth) acrylic polymer as the acrylic plasticizer may be a polymer Y having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring. .

The polymer X is preferably represented by the following general formula (X), and the polymer Y is preferably represented by the following general formula (Y).

Formula (X): — [CH ₂ —C (—Rc) (— CO ₂ Rd)] _m — [CH ₂ —C (—Re) (— CO ₂ Rf—OH) —] _n — [Xc] _p -
Formula (Y): Ry— [CH ₂ —C (—Rg) (— CO ₂ Rh—OH) —] _k — [Yb] _q —
In Formula (X) or Formula (Y), Rc, Re, and Rg represent H or a methyl group. Rd represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. Rf and Rh represent —CH ₂ —, —C ₂ H ₄ —, or C ₃ H ₆ —. Ry represents a hydroxy group, H or an alkyl group having 3 or less carbon atoms. Xc represents a monomer unit that can be polymerized to Xa and Xb. Yb represents a monomer unit copolymerizable with Ya. m, n, k, p, and q represent a molar composition ratio. However, m ≠ 0, n ≠ 0, k ≠ 0, m + n + p = 100, and k + q = 100.

The addition amount of these plasticizers is preferably within a range of 0.5 to 30% by mass, and particularly preferably within a range of 5 to 20% by mass with respect to the thermoplastic resin.

[Other resins]
The optical film of the present invention contains a thermoplastic resin, but may contain other resins other than the thermoplastic resin that is mainly contained. Examples of other resins include cellulose ether resins, polycarbonate resins, polystyrene resins, polysulfone resins, polyester resins, polyarylate resins, acrylic resins, olefin resins (norbornene resins, cyclic olefins). Resin, cyclic conjugated diene resin, vinyl alicyclic hydrocarbon resin, etc.). Preferable examples of other resins include cellulose ester resins, polycarbonate resins, acrylic resins, and cyclic olefin resins. When other resins are used, the content thereof is preferably in the range of 5 to 70% by mass of the optical film.

[Ultraviolet absorber]
The optical film of the present invention may contain an ultraviolet absorber, and may contain two or more ultraviolet absorbers. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet light having a wavelength of 400 nm or less, and the transmittance at a wavelength of 370 nm is particularly preferably 10% or less, more preferably 5% or less. Preferably it is 2% or less.

The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, and the like. .

Specific examples of ultraviolet absorbers include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl)- 6- (Linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone and the like are included. In addition, there are tinuvins such as tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, and tinuvin 928, which are commercially available from BASF Japan and can be preferably used.

The UV absorber is a benzotriazole-based UV absorber, a benzophenone-based UV absorber, or a triazine-based UV absorber, and particularly preferably a benzotriazole-based UV absorber or a benzophenone-based UV absorber. In addition, a discotic compound such as a compound having a 1,3,5-triazine ring is also preferable as the ultraviolet absorber.

The UV absorber may be a polymer UV absorber; in particular, a polymer type UV absorber described in JP-A-6-148430 is preferred.

Addition of the UV absorber is performed by dissolving the UV absorber in an alcohol such as methanol, ethanol, butanol, an organic solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof, or You may add directly in dope composition. Moreover, the agent which does not melt | dissolve in an organic solvent like an inorganic powder uses a dissolver and a sand mill in an organic solvent and a cellulose ester, and is added to dope after dispersing.

The content of the ultraviolet absorber in the optical film is preferably in the range of 0.5 to 10% by mass, more preferably in the range of 0.6 to 4% by mass when the dry film thickness of the optical film is 30 to 200 μm. However, it is adjusted according to the type of UV absorber, usage conditions, and the like.

[Antioxidant]
Antioxidants are also referred to as deterioration inhibitors. When a liquid crystal image display device or the like is placed in a high humidity and high temperature state, the optical film may be deteriorated. The antioxidant delays or suppresses the decomposition of the optical film due to, for example, halogen in the residual solvent amount in the optical film, phosphoric acid of the phosphoric acid plasticizer, or the like.

The antioxidant is preferably a hindered phenol compound, for example. Examples of hindered phenol compounds include 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]. , Triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 2,2- Thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxy Phenyl) propionate, N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris (3 , 5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate and the like. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred.

Antioxidants include hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, tris (2,4- A phosphorus processing stabilizer such as di-t-butylphenyl) phosphite may be used in combination.

The addition amount of the antioxidant in the optical film of the present invention is preferably in the range of 1 ppm to 1.0%, more preferably in the range of 10 to 1000 ppm, by mass ratio with respect to the thermoplastic resin.

[Fine particles]
The optical film of the present invention may contain fine particles in order to improve slipperiness. The dynamic friction coefficient of one surface of the optical film of the present invention is preferably in the range of 0.2 to 1.0.

The fine particles may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate And calcium phosphate. Examples of organic fine particles include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, melamine Examples thereof include resins, polyolefin-based powders, polyester-based resins, polyamide-based resins, polyimide-based resins, polyfluorinated ethylene-based resins, and pulverized and classified products of organic polymer compounds such as starch. Furthermore, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray drying method or a dispersion method, or an inorganic compound can also be used as fine particles. Among these, fine particles containing silicon are preferable, and silicon dioxide is particularly preferable. This is to reduce the turbidity of the optical film.

The average primary particle size of the fine particles is preferably in the range of 5 to 400 nm, more preferably in the range of 10 to 300 nm. In the optical film, the fine particles may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm. If the average primary particle size of the fine particles is in the range of 100 to 400 nm, it is also preferable that the primary particles are contained in the optical film without agglomeration.

The content of fine particles in the optical film is preferably in the range of 0.01 to 1% by mass, particularly preferably in the range of 0.05 to 0.5% by mass. In the case of an optical film having a multilayer structure formed by a co-casting method, it is preferable that fine particles of this addition amount are disposed on the film surface.

Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.).

Examples of organic fine particles include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name.

Among these, Aerosil 200V and Aerosil R972V are particularly preferred because they have a large effect of reducing the friction coefficient while keeping the turbidity of the optical film low.

Arbitrary components (various additives) may be batch-added to a dope that is a thermoplastic resin-containing solution before film formation, or an additive solution may be separately prepared and added in-line. In particular, it is preferable to add a part or all of the fine particles in-line in order to reduce the load on the filter medium.

When the additive solution is added in-line, it is preferable to add a small amount of thermoplastic resin to the additive solution in order to improve mixing with the dope. The amount of the thermoplastic resin in the additive solution is preferably in the range of 1 to 10 parts by mass, more preferably in the range of 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

The in-line addition and mixing are preferably performed using an in-line mixer such as a static mixer (manufactured by Toray Engineering) or SWJ (Toray static type in-pipe mixer Hi-Mixer).

<Method for producing optical film>
The manufacturing method of the optical film of this invention is demonstrated. The optical film according to the present invention can be produced by either a solution casting method or a melt casting method.

The production of the optical film of the present invention includes a step of preparing a dope by dissolving a thermoplastic resin and an additive in a solvent, a step of casting the dope on an endless metal support that moves infinitely, and a cast dope. It is carried out by a step of drying as a web, a step of peeling from a metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished film.

(Dope preparation process)
The process for preparing the dope will be described. A high concentration of the thermoplastic resin in the dope is preferable because the drying load after casting on the metal support is reduced. On the other hand, if the concentration of the thermoplastic resin in the dope is too high, the load during filtration increases and the filtration accuracy deteriorates. Therefore, the concentration of the thermoplastic resin in the dope is preferably in the range of 10 to 35% by mass, and more preferably in the range of 15 to 25% by mass.

The dope solvent is a single solvent or a mixed solvent of two or more, but a mixed solvent of a good solvent and a poor solvent for thermoplastic resin is preferable in terms of production efficiency. A larger amount of good solvent is preferable in terms of solubility of the thermoplastic resin. A preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. Those that dissolve the thermoplastic resin used alone are defined as good solvents, and those that swell or do not dissolve alone are defined as poor solvents. When the thermoplastic resin is a cellulose ester, the types of good and poor solvents vary depending on the average degree of acetylation (acetyl group substitution degree). For example, acetone is a good solvent for cellulose acetate ester (acetyl group substitution degree 2.4) and cellulose acetate propionate, and is a poor solvent for cellulose acetate ester (acetyl group substitution degree 2.8).

Examples of good solvents include, but are not limited to, organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.

Examples of the poor solvent include methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, and the like, but are not particularly limited. The content of water in the dope is preferably in the range of 0.01 to 2% by mass.

The dope solvent is removed and recovered from the film by drying in the film-forming process. The recovered solvent can be reused. There may be a trace amount of additives such as plasticizers, UV absorbers, polymers, monomer components, etc. in the recovered solvent, but even if these are included, they can be reused and are necessary. It can be purified and reused.

A general method can be used for dissolving the thermoplastic resin in the preparation of the dope. If heated while applying pressure, it can be heated to a temperature equal to or higher than the boiling point at normal pressure. When the solution is stirred and dissolved at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and the solvent does not boil under pressure, the generation of massive undissolved materials called gels and mamaco can be prevented. It is also preferable to add a good solvent and dissolve after mixing the thermoplastic resin with a poor solvent to wet or swell.

Pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of developing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside, while a jacket type heater, for example, is preferable because of easy temperature control.

A higher heating temperature is preferable because the solubility of the thermoplastic resin is improved. On the other hand, when the heating temperature is too high, the reaction pressure increases and the productivity decreases. The preferred heating temperature is in the range of 45 to 120 ° C, more preferably in the range of 60 to 110 ° C, and still more preferably in the range of 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

For the preparation of the dope, a cooling dissolution method is also preferably used. The thermoplastic resin can be dissolved in a solvent such as methyl acetate by a cooling dissolution method.

Next, the thermoplastic resin solution is filtered using an appropriate filter medium such as filter paper. The absolute filtration accuracy of the filter medium is preferably small in order to remove insoluble matters and the like. However, if the absolute filtration accuracy is too small, the filter medium is likely to be clogged. Therefore, a filter medium having an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium in the range of 0.001 to 0.008 mm is more preferable, and a filter medium in the range of 0.003 to 0.006 mm is more preferable.

The material of the filter medium is not particularly limited, and a normal filter medium can be used. Plastic filter media such as polypropylene and Teflon (registered trademark) and metal filter media such as stainless steel are preferred because they do not drop off fibers. It is preferable to remove and reduce impurities, particularly bright spot foreign matters, contained in the raw material cellulose ester by filtration.

A bright spot foreign object is when two polarizing plates are placed in a crossed Nicols state, an optical film is placed between them, and light is applied from one polarizing plate side, and observed from the other polarizing plate side. It is a point (foreign matter) where light from the opposite side appears to leak. The number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less, more preferably 100 / cm ² or less, still more preferably 50 / cm ² or less, and still more preferably. 0 to 10 pieces / cm ² or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

The filtration of the thermoplastic resin solution can be performed by a usual method. Filtration at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is preferable because the difference in filtration pressure before and after filtration (referred to as differential pressure) is small. The preferred temperature is in the range of 45 to 120 ° C, more preferably in the range of 45 to 70 ° C, and still more preferably in the range of 45 to 55 ° C. The pressure in the filtration environment is preferably small, preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

(Dope casting, drying, peeling process)
Next, the dope is cast. The surface of the metal support in the casting (casting) process is preferably mirror-finished. The metal support is preferably a stainless steel belt or a drum whose surface is plated with a casting. The width of the cast can be in the range of 1-4 m.

The surface temperature of the metal support in the casting process can be set at a temperature between −50 ° C. and less than the boiling point of the solvent. A higher surface temperature of the metal support is preferable because the web drying speed can be increased. On the other hand, if the surface temperature of the metal support is too high, the web may foam or the flatness may deteriorate. The support temperature is preferably in the range of 0 to 40 ° C, more preferably in the range of 5 to 30 ° C. Moreover, it is also preferable to peel from a drum in the state which gelled the web by cooling a metal support body and contained much residual solvent.

The method for controlling the temperature of the metal support is not limited, but there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

In order to improve the flatness of the obtained optical film, the amount of residual solvent in the web when peeled from the metal support is preferably in the range of 10 to 150% by mass, more preferably in the range of 20 to 40% by mass or 60%. Is particularly preferably in the range of 20-30% by weight or in the range of 70-120% by weight.

In the present invention, the amount of residual solvent is defined by the following formula. In the formula below, “M” is the mass of the web or film taken at any time during or after production. “N” is the mass after heating the web or film at 115 ° C. for 1 hour.

Residual solvent amount (% by mass) = {(MN) / N} × 100
(Stretching process)
The web peeled from the metal support is preferably stretched. Specifically, the web is preferably stretched in the width direction (lateral direction) by a tenter method in which both ends of the web are gripped by clips or the like. The peel tension is preferably 300 N / m or less.

It is preferable to perform refractive index control (retardation control) by stretching the web peeled from the metal support.

Stretching can be, for example, uniaxially stretched in the longitudinal direction (film forming direction) of the film or in the direction perpendicular to the film plane (that is, the width direction), or biaxially stretched in both directions sequentially or simultaneously. Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension.

The draw ratios in the biaxial directions perpendicular to each other are preferably finally in the range of 0.8 to 1.5 times in the casting direction and in the range of 1.1 to 2.5 times in the width direction; The range is preferably 0.9 to 1.0 times in the casting direction and 1.2 to 2.0 times in the width direction.

The stretching temperature is preferably in the range of 120 ° C to 200 ° C, more preferably in the range of 140 ° C to 180 ° C. The residual solvent in the film at the time of stretching is preferably in the range of 20 to 0%, more preferably in the range of 15 to 0%.

The method for stretching the web is not particularly limited. For example, a method in which a difference in peripheral speed is applied to a plurality of rollers, and the rollers are stretched in the longitudinal direction using the difference in peripheral speed between the rollers, and both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. These methods may be combined. In the case of the so-called tenter method, when the clip portion is driven by the linear drive method, smooth stretching can be performed, and the risk of breakage and the like can be reduced.

It is preferable to carry out the width maintenance or lateral stretching in the film forming step by a tenter, and it may be a pin tenter or a clip tenter. In addition, you may extend | stretch sequentially, even if a conveyance direction and the width direction are extended | stretched simultaneously.

(Film drying process)
The stretched film is further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0 to 0.01% by mass or less. In the film drying process, a roller drying method (a method in which webs are alternately passed through a plurality of rollers arranged above and below) and a method of drying while transporting the web by a tenter method are adopted.

The means for drying the stretched film is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roller, a microwave, or the like, but is preferably performed with hot air from the viewpoint of simplicity. The drying temperature in the web drying step is preferably increased stepwise in the range of 40 to 200 ° C.

In addition, although the solution casting film forming method was described here, it does not prevent producing a film by the melt casting film forming method.

<Characteristics of optical film>
The film thickness of the optical film of the present invention is not particularly limited, but is preferably in the range of 10 to 200 μm, more preferably in the range of 10 to 100 μm, and still more preferably in the range of 20 to 60 μm. If it is this range, since the improvement of the moisture permeability depending on the film thickness of a film and the expression property of retardation can be compatible, it is preferable. Moreover, the slitting characteristic of the optical film having a film thickness in this range is improved.

The width of the optical film of the present invention is preferably in the range of 1 to 4 m, more preferably in the range of 1.4 to 4 m, and particularly preferably in the range of 1.6 to 3 m. If it exceeds 4 m, conveyance becomes difficult.

The moisture permeability of the optical film of the present invention is preferably in the range of 10 to 1200 g / m ² · 24 h at 40 ° C. and 90% RH. The moisture permeability can be measured according to the method described in JIS Z 0208: 1976.

The breaking elongation of the optical film of the present invention is preferably in the range of 10 to 80%. The elongation at break can be determined by measurement according to JIS-K7127-1999.

The visible light transmittance of the optical film of the present invention is preferably 90% or more, and more preferably 93% or more. A visible light transmittance (Tv) at 380 to 780 nm was measured using a U-4000 self-recording spectrophotometer manufactured by Hitachi, Ltd. according to the method measured by JIS Z 8722.

The haze of the optical film of the present invention is preferably less than 1%, particularly preferably in the range of 0 to 0.1%. Measurement is performed using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.).

The wet heat resistance of the optical film of the present invention can be evaluated by dimensional change with respect to humidity change. Evaluation of the dimensional change with respect to the wet heat change is performed by the following method. Two marks (crosses) are provided in the casting direction of the produced optical film. This is treated at a temperature of 60 ° C. and a relative humidity of 90% RH for 1000 hours. The distance between the marks (crosses) before and after treatment is measured with an optical microscope. The dimensional change rate (%) is calculated by the following formula.

Dimensional change rate (%) = [(a1-a2) / a1] × 100
a1: Distance before wet heat treatment a2: Distance after wet heat treatment When the protective film for a polarizing plate of a liquid crystal display device changes its dimensions due to moisture absorption, unevenness or change in retardation value occurs, resulting in problems such as lowering of contrast or color unevenness Is generated. In particular, this problem tends to occur remarkably in a polarizing plate protective film used for a liquid crystal display device used outdoors. Therefore, when the optical film of the present invention is used as a protective film for a polarizing plate of a liquid crystal display device, the dimensional change rate (%) is preferably less than 0.5%, more preferably less than 0.3%. preferable. If it is such a dimensional change rate, it can be evaluated that it is an optical film which shows sufficient low hygroscopicity.

A liquid crystal layer or a resin layer may be applied and formed on the optical film of the present invention, and further stretched. The resulting laminated film can have retardation values over a wider range.

<Use of optical film>
The optical film of the present invention is preferably a functional film used for various display devices such as a liquid crystal display, a plasma display, and an organic EL display. Specifically, the optical film of the present invention is a polarizing plate protective film for liquid crystal display devices, a retardation film, an antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, an enlarged viewing angle, etc. Or an optical compensation film. Typically, the optical film of the present invention is a polarizing plate protective film, a retardation film, or an optical compensation film. The optical film of the present invention can serve as both a retardation film and a polarizing plate protective film.

(Optical compensation film)
Since liquid crystal displays use anisotropic liquid crystal materials and polarizing plates, there is a problem of viewing angle that even when good display is obtained when viewed from the front, display performance is degraded when viewed from an oblique direction. . Therefore, a viewing angle compensator is necessary to improve the performance of the liquid crystal display. The average refractive index distribution of the liquid crystal cell is larger in the cell thickness direction and smaller in the in-plane direction. Therefore, the viewing angle compensator must cancel this anisotropy. In other words, it is effective that the viewing angle compensation plate has a refractive index smaller than that in the in-plane direction, that is, a so-called negative uniaxial structure. The optical film of the present invention can be an optical compensation film having such a function.

When the optical film of the present invention is used for a VA mode liquid crystal cell, a total of two optical films may be used, one on each side of the cell (two-sheet type), or one of the upper and lower sides of the cell. An optical film may be used only on the side (single sheet type).

In the optical film of the present invention, the retardation value Ro in the in-plane direction represented by the following formula is preferably in the range of 40 to 150 nm at a measurement wavelength of 590 nm in an environment of 23 ° C. and 55% RH. More preferably in the range of 50 nm to 130 nm. The retardation value Rth in the thickness direction is preferably in the range of 70 to 350 nm and more preferably in the range of 170 nm to 270 nm at a measurement wavelength of 590 nm in an environment of 23 ° C. and 55% RH.

These retardation values can be measured using an automatic birefringence meter KOBRA-WPR (Oji Scientific Instruments).

Formula _{(I) Ro = (n x} -n y) × d
Formula (II) Rth = {(n _x + n _y ) / 2−n _z } × d
(N _x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the optical film, n _y is in the plane direction of the optical film, the refractive index in the direction y perpendicular to the direction x , _Nz represents the refractive index in the thickness direction z of the optical film, and d (nm) represents the thickness of the optical film.)
The optical film of the present invention has a slow axis or a fast axis in the film plane, and the angle “θ1” formed by the slow axis or the fast axis and the film forming direction axis is −1 ° or more and + 1 °. Or less, more preferably −0.5 ° or more and + 0.5 ° or less. θ1 can be defined as an orientation angle, and the measurement of θ1 can be performed using an automatic birefringence meter KOBRA-WPR (Oji Scientific Instruments). An optical film in which θ1 satisfies the above relationship increases the brightness of a display image of a liquid crystal display device including the same, suppresses or prevents light leakage, and faithfully reproduces color in a color liquid crystal display device.

<Polarizing plate>
The optical film of this invention can be used for a polarizing plate and a liquid crystal display device provided with the same. The optical film of the present invention is preferably a film that doubles as a polarizing plate protective film and a retardation film. In that case, it is not necessary to prepare a retardation film separate from the polarizing plate protective film. Therefore, the thickness of the liquid crystal display device can be reduced and the manufacturing process can be simplified.

The polarizing plate has a polarizer and a polarizing plate protective film bonded to one or both surfaces of the polarizer.

A polarizer is an element that allows only light of a plane of polarization in a certain direction to pass through. A typical polarizer is a polyvinyl alcohol polarizing film, which is dichroic with a polyvinyl alcohol film dyed with iodine. There are dyed dyes.

The polarizer is obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching or dyeing or uniaxially stretching the dye, and then preferably performing a durability treatment with a boron compound. The thickness of the polarizer is preferably in the range of 5 to 30 μm, particularly preferably in the range of 10 to 20 μm.

The polarizing plate of the present invention can be produced by a general method. The surface of the optical film of the present invention attached to the polarizer is subjected to alkali saponification treatment. The optical film of the present invention is bonded to at least one surface of a polarizer produced by immersing and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. Another conventional polarizing plate protective film may be bonded to the other surface of the polarizer.

Examples of conventional polarizing plate protective films include commercially available cellulose ester films (for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE-HA-C KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, and the like manufactured by Konica Minolta Advanced Layer Co., Ltd.).

<Liquid crystal display device>
The liquid crystal display device of the present invention includes a polarizing plate including the optical film of the present invention. Specifically, the optical film of the present invention is included in the polarizing plate disposed in at least one of the liquid crystal cells; the film on the liquid crystal cell side of the polarizing plate is the optical film of the present invention.

In the liquid crystal display device of the present invention, it is preferable that a polarizing plate is bonded to one or both surfaces of the liquid crystal cell via an adhesive layer.

The polarizing plate protective film used on the surface side of the liquid crystal display device of the present invention preferably has an antireflection layer, an antistatic layer, an antifouling layer, and a backcoat layer in addition to the antiglare layer or the clear hard coat layer. .

The optical film and polarizing plate of the present invention can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB. In particular, it is preferably used for a VA (MVA, PVA) type liquid crystal display device. In particular, even when used in a liquid crystal display device having a large screen of 30 type or more, coloring during black display due to light leakage can be reduced and visibility such as front contrast can be improved. Thus, the liquid crystal display device of the present invention is excellent in various visibility.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
The detail of the used cellulose ester used in Example 1 is shown.

Cellulose ester A: Cellulose diacetate having a number average molecular weight of 70,000 having an acetyl group substitution degree of 2.40 (denoted as DAC in the table)
Cellulose ester B: Cellulose acetate propionate having a number average molecular weight of 70,000 having an acetyl group substitution degree of 1.58, a propionyl group substitution degree of 0.9, and a total acyl group substitution degree of 2.48 (denoted as CAP in the table)
Cellulose ester C: Cellulose triacetate having a number average molecular weight of 70,000 having an acetyl group substitution degree of 2.85 (denoted as TAC in the table)
<Preparation of optical film 101>
<Preparation of fine particle dispersion>
11.3 parts by mass of fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) and 84 parts by mass of ethanol were stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Preparation of fine particle additive solution 1>
To the well-stirred methylene chloride (100 parts by mass) in the dissolution tank, 5 parts by mass of the fine particle dispersion was slowly added. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

<Preparation of main dope>
A main dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose ester A was added to a pressurized dissolution tank containing a solvent while stirring, and this was heated and completely dissolved while stirring.

<Composition of main dope>
Methylene chloride 340 parts by mass Ethanol 60 parts by mass Cellulose ester A 100 parts by mass Retardation developer: Exemplified compound A-002 3 parts by mass Sugar ester The following compounds 5 parts by mass Fine particle additive solution 1 1 part by mass

Further, the additive component was put into a closed container and dissolved while stirring, and this was dissolved into Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. The main dope was prepared by filtration using 244. Next, using an endless belt casting apparatus, the dope was cast uniformly on a stainless steel belt support at a temperature of 31 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 28 ° C.

On the stainless steel belt support, the solvent was evaporated until the amount of residual solvent in the cast film was 75%. Subsequently, it peeled from the stainless steel belt support body with the peeling tension of 128 N / m. The peeled film was stretched 24% in the width direction using a tenter while applying heat at 142 ° C. The residual solvent at the start of stretching was 17%.

Next, drying was completed while the drying zone was conveyed by a number of rollers. The drying temperature was 120 ° C. and the transport tension was 122 N / m. As described above, an optical film 101 having a dry film thickness of 40 μm was obtained.

<Preparation of optical films 102 to 141>
In the production of the optical film 101, only the types and amounts (parts by mass) of the exemplified compounds of the compound represented by the general formula (1) as the type of cellulose ester and the retardation developer are changed as shown in Table 1 and Table 2. Except for the above, optical films 102 to 131 of the present invention and comparative optical films 132 to 141 were produced in the same manner. The amount of cellulose ester added instead of cellulose ester A (DAC) used was the same mass part as cellulose ester A (DAC).

The structures of retardation developing agents (C-001 to C-005) used for the production of comparative optical films 132 to 138 are shown.

<< Evaluation of optical film >>
The produced optical films 101 to 141 were evaluated as follows. The evaluation results are shown in Tables 1 and 2.

(Retardation)
The average refractive index of the optical film was measured using an Abbe refractometer (4T). Moreover, the thickness of the optical film was measured using a commercially available micrometer.

Retardation of an optical film at a wavelength of 590 nm in an optical film left for 24 hours in an environment of 23 ° C. and 55% RH using an automatic birefringence meter KOBRA-WPR (manufactured by Oji Scientific Instruments) Was measured. The average refractive index and the film thickness were input into the following formula, and the retardation value Ro in the in-plane direction and the retardation value Rth in the thickness direction were determined. The direction of the slow axis was also measured at the same time. In the following formulas, n _x is the maximum refractive index in the film plane, n _y is a refractive index of n _x direction orthogonal, n _z is the film thickness direction of the refractive index, d represents the thickness of the film (nm).

Formula _{(I) Ro = (n x} -n y) × d
Formula (II) Rth = {(n _x + n _y ) / 2−n _z } × d
(Internal haze value)
The prepared cellulose acetate film was conditioned for 5 hours or more in an environment of 23 ° C. and 55% RH, and then the internal haze value was evaluated by the following method.

<Internal haze measuring device>
Haze meter (turbidity meter) (model: NDH 2000, manufactured by Nippon Denshoku Industries Co., Ltd.)
A 5V9W halogen bulb was used as the light source, and a silicon photocell (with a relative visibility filter) was used as the light receiving unit.

The cellulose acetate film of the present invention preferably has a value of 0.05 or less in the haze measurement of the film when a solvent having a refractive index of ± 0.05 is dropped onto the film with this apparatus. . The measurement conditions were measured according to JIS K-7136.

Measure internal haze as follows. A description will be given with reference to FIGS.

First, the blank haze 1 of a measuring instrument other than the film is measured.

1. Drip a drop (0.05 ml) of glycerin on a cleaned glass slide. At this time, care is taken so that bubbles do not enter the droplet. Glass must be washed with a detergent (see Fig. 1).

2. Place the cover glass on top of it. Glycerin spreads without pressing the cover glass.

3. Set on a haze meter and measure blank haze 1.

Next, the haze 2 including the sample is measured according to the following procedure.

4. 0.05 ml of glycerin is dropped on the slide glass (see FIG. 1).

5. A sample film to be measured is placed thereon so that air bubbles do not enter (see FIG. 2).

6. 0.05 ml of glycerin is dropped on the sample film (see FIG. 3).

7. A cover glass is placed thereon (see FIG. 4).

8. The laminate prepared as described above (from above, cover glass / glycerin / sample film / glycerin / slide glass) is set on a haze meter and haze 2 is measured.

9. (Haze 2) − (Haze 1) = (Internal haze of the cellulose acetate film of the present invention) is calculated.

All the above haze measurements were performed at 23 ° C. and 55% RH.

Moreover, the slide glass and glycerin used in the above measurement are as follows.

Glass: MICRO SLIDE GLASS S9213 MATUNAMI
Glycerin: Kanto Kagaku Deer Special Grade (Purity> 99.0%) Refractive index 1.47
(Bleed-out resistance)
Durability was evaluated by the bleed-out resistance described below. The optical film was allowed to stand for 1000 hours in a high-temperature and high-humidity atmosphere at 80 ° C. and 90% RH, and then the presence or absence of bleed-out (crystal precipitation) on the optical film surface was visually observed. From the observation results, evaluation was performed according to the following criteria. Evaluations A and B were judged to be at a level where there was no practical problem.

A: No bleed-out is observed on the surface B: Partial bleed-out is slightly observed on the surface C: Slight bleed-out is observed on the entire surface D: Clear on the entire surface Bleed-out is recognized (Heat and heat resistance: dimensional change in response to wet heat change)
Two marks (crosses) were placed in the casting direction of the produced optical film, treated at 60 ° C. and 90% RH for 1000 hours, and the distance between the marks (crosses) before and after treatment was measured with an optical microscope. . From the measurement results, wet heat resistance was evaluated as the durability of the optical film by evaluating the dimensional change according to the following criteria.
Dimensional change rate (%) = [(a1-a2) / a1] × 100 (a1 represents a distance before wet heat treatment, a2 represents a distance after wet heat treatment)
A: Less than 0.3% B: 0.3% to less than 0.5% C: 0.5% to less than 0.7% D: 0.7% or more (Compatibility evaluation)
The film before stretching in the production of the optical film was dried at 120 ° C. for 15 minutes, and the haze of the film was measured using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.). From the measurement results, evaluation was performed according to the following criteria. Evaluation A and B were judged to be a level which is satisfactory practically.

A: Haze is less than 0.5% B: Haze is less than 0.5-1.0% C: Haze is less than 1.0-1.5% D: Haze is 1.5% or more E: Compound is precipitated ( Haze after stretching)
The haze of the produced optical film was measured using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.). From the measurement results, evaluation was performed according to the following criteria. Evaluations A and B were judged to be at a level where there was no practical problem.

A: Haze is less than 0.5% B: Haze is less than 0.5-1.0% C: Haze is less than 1.0-1.5% D: Haze is 1.5% or more E: Compound is precipitated

As shown in Tables 1 and 2, the optical films 101 to 131 of the examples are superior in retardation to the optical films 132 to 141 of the comparative examples, and have an internal haze and compatibility (haze). And, durability (bleed out resistance) is good, and it can be seen that the optical film is practically excellent.

From comparison with the results of the optical films 132 to 135 using the comparative compounds C-001, C-002, and C-004, when the compound as a retardation developer has a specific substituent, the internal haze value is low. Thus, it can be seen that the compatibility and the expression of retardation are improved. Further, C-003 and C-005 had poor compatibility and the compound was deposited in the film, so that it was impossible to measure the retardation value and the internal haze.

From the results of the optical films 101 to 131 of the examples, particularly 124 to 129, the optical film containing the retardation developing agent of the present invention exhibits a large retardation, and the cellulose ester even when the addition amount of the retardation developing agent is increased. It is understood that this is an excellent optical film having a low internal haze and a high retardation value.

On the other hand, the optical film 141 that uses TAC as the cellulose ester and does not contain a retardation enhancer has a small retardation value and does not have a function as an optical compensation film.

Example 2
Using the main dope used in the production of the optical film 104 of Example 1, the dope flow rate during casting was changed to produce optical films 201 to 206 having the film thicknesses shown in Table 3. It was produced in the same manner as in Example 1 except for the dope flow rate at the time of casting. The optical films 201 to 206 were evaluated in the same manner as in Example 1. At that time, the optical film 132 produced in Example 1 was added as a comparative example.

The brittleness was evaluated by the following evaluation method.

(Slitting aptitude)
Brittleness was evaluated by the slitting aptitude described below. A 60 ° worn upper blade and a 90 ° lower blade were attached to a hydraulic table press so as to have a spacing of 30 μm. Each optical film was placed between the two blades, and 100 samples having a width of 90 cm and a length of 100 cm were continuously cut out at a descending speed of the upper blade of 6 m / min. The cut surfaces of the cut samples were observed at 50 times using an optical microscope, and the sharpness was compared. The number of films with some defects such as burrs, cleaving, cutting, and chip generation was counted, the defect rate was calculated, and the slitting suitability was evaluated according to the following criteria. Evaluation A and B were judged to be a level which is satisfactory practically.

A: The defect rate is less than 2% B: The defect rate is less than 2-5% C: The defect rate is less than 5-10% D: The defect rate is 10% or more

As is apparent from Table 3, the optical films 201 to 206 of the examples are excellent in retardation development, and are excellent in brittleness (slitting suitability) and durability (bleedout resistance). Furthermore, it can be seen that the optical films 202 to 205 having a film thickness in the range of 20 to 60 μm are particularly effective.

The optical film 132 of the comparative example has a film thickness of 40 μm, but both brittleness (slitability) and durability (bleedout resistance) were inferior.

Example 3
<Production and evaluation of polarizing plate>
A 120 μm-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). The obtained stretched film was immersed in an aqueous solution consisting of 0.069 g of iodine, 4.5 g of potassium iodide and 100 g of water for 52 seconds, and then 60 ° C. consisting of 6.5 g of potassium iodide, 7.0 g of boric acid and 100 g of water. Soaked in an aqueous solution. This was washed with water and dried to obtain a polarizer.

Then, according to the following steps 1 to 5, the optical films 101 to 141 and the optical films 201 to 206 are bonded to one surface of the polarizer; and the other surface of the polarizer is Konica Minolta Tack KC4UY (Konica Minolta Advanced). The polarizing plates 101 to 141 and the polarizing plates 201 to 206 were produced by laminating layers (cellulose ester film manufactured by Layer Co., Ltd.).

Step 1: Optical films 101 to 141 and optical films 201 to 206 are immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 95 seconds, then washed with water and dried to saponify the side to be bonded to the polarizer. An optical film was obtained.

Step 2: The polarizer was immersed for 1 to 2 seconds in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass, and then excess adhesive adhered to the polarizer was gently wiped off.

Step 3: The polarizer obtained in Step 2 was placed on the optical film treated in Step 1.

Step 4: The optical film and the polarizer in the laminate obtained in Step 3 were bonded at a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.

Step 5: The laminated polarizer prepared in Step 4 and a Konica Minoltack KC4UY are bonded to each other in a dryer at 80 ° C. and dried for 2 minutes to produce the polarizing plates 101 to 141 and the polarizing plates 201 to 206. did.

The durability of the produced polarizing plate was evaluated as follows. The results are shown in Table 4.

(Light resistance)
The parallel transmittance (H0) and orthogonal transmittance (H90) of the sample subjected to forced degradation were not measured. From the measured value, the polarization degree P0 was calculated according to the following formula. Thereafter, each polarizing plate was subjected to forced deterioration treatment under the conditions of a sunshine weather meter for 500 hours and no UV cut filter. Thereafter, the parallel transmittance (H0 ′) and the orthogonal transmittance (H90 ′) were measured again. From the measured value, the polarization degree P500 after the forced deterioration treatment was calculated according to the following formula.

Polarization degree P0 = [(H0−H90) / (H0 + H90)] ^1/2 × 100
Polarization degree P500 = [(H0′−H90 ′) / (H0 ′ + H90 ′)] ^1/2 × 100
From the calculated degree of polarization P0 and the degree of polarization P500, the amount of change in the degree of polarization was calculated according to the following formula.

Polarization degree change = P0−P500
The light resistance was evaluated based on the following criteria for the obtained degree of polarization change. Evaluations A and B were judged to be at a level where there was no practical problem.

A: Polarization degree change amount is less than 2% B: Polarization degree change amount is 2% or more and less than 10% C: Polarization degree change amount is 10% or more and less than 25% D: Polarization degree change amount is 25% or more (moisture heat resistance)
Two polarizing plates of 500 mm × 500 mm were prepared. Each was wet-heat treated (conditions: left at 70 ° C. and 90% RH for 100 hours). Two polarizing plates were laminated so as to be in a crossed Nicols state. When light was irradiated from one surface of the laminated body, the length of the white portion generated at the edge portion of the other surface was measured. The white spot portion to be measured is the longest white spot portion among a plurality of white spot portions generated near the center of each of the four edge portions of the polarizing plate. The white spots generated at the edge portion mean that light passes through the edge portion of the polarizing plate that does not transmit light in the crossed Nicols state, and this is the cause of the failure that the image is not displayed at the edge portion of the polarizing plate. Become.

The ratio of the measured white spot length to the length of one side of the polarizing plate (500 mm) was calculated. From the ratio, it was determined that evaluations A and B, which were evaluated for moisture and heat resistance based on the following criteria, were practically acceptable levels.

A: Edge whiteness is less than 5% (a level that is not a problem as a polarizing plate)
B: White outline of edge is 5% or more and less than 10% (a level at which no problem as a polarizing plate)
C: White edge of edge is 10% or more and less than 20% (a level that can be managed as a polarizing plate)
D: Edge blank is 20% or more (a problematic level as a polarizing plate)

As is clear from Table 4, the polarizing plates 101 to 131 and the polarizing plates 201 to 206 of the examples are practically excellent polarizing plates that have better light resistance and wet heat resistance than the comparative polarizing plates 132 to 141. is there. From the comparison with the results of the polarizing plates 132 to 138 using the comparative compounds C-001, C-002, C-003, C-004, and C-005, the retardation developer compound has a specific structure and substituent. It turns out that the subject of this invention can be achieved by having.

From the results of the polarizing plates 101 to 131, particularly the polarizing plates 124 to 129, the retardation of the optical film containing the retardation developer according to the present invention is large, and the retardation is exhibited even when the amount of the retardation developer is increased. The agent is compatible with the cellulose ester. Therefore, the polarizing plate of the present invention is a practically excellent polarizing plate.

Example 4
<Production and evaluation of liquid crystal display device>
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics of the liquid crystal display device were evaluated. In the Sony 40-type display KLV-40J3000, the polarizing plates on both sides attached to the liquid crystal cell were peeled off. Instead, the produced polarizing plates 101 to 141 and polarizing plates 201 to 206 were bonded to both surfaces of the glass surface of the liquid crystal cell, respectively. The polarizing plate is bonded so that the optical films of Examples and Comparative Examples are on the liquid crystal cell side, and the direction of the absorption axis of the polarizing plate to be bonded is the direction of the absorption axis of the polarizing plate previously bonded. I went to be the same. In this way, the liquid crystal display devices 101 to 141 and the liquid crystal display devices 201 to 206 were produced.

The liquid crystal display device produced as described above was evaluated as described below. The results are shown in Tables 6 and 7.

(Front contrast unevenness)
In an environment of 23 ° C. and 55% RH, the backlight of each liquid crystal display device was lit continuously for one week. Then, the brightness | luminance from the normal line direction of the display screen of the white display of a liquid crystal display device and a black display was measured. For the measurement, EZ-Contrast 160D manufactured by ELDIM was used. The measured luminance ratio was defined as the front contrast. The front contrast is defined by a formula (brightness of white display measured from the normal direction of the display device / brightness of black display measured from the normal direction of the display device).

The front contrast of any 5 points on the display screen of the liquid crystal display device was measured and evaluated according to the following criteria. Evaluations A and B were judged to be at a level where there was no practical problem.

A: Variation with front contrast of 0 to less than 5% and small variation B: Variation with front contrast of less than 5 to 10% and slight variation C: Variation with front contrast of 10% or more, Unevenness (viewing angle degradation)
The viewing angle of a liquid crystal display device placed in an environment of 25 ° C. and 50% RH for 5 hours was measured. Subsequently, the viewing angle of the liquid crystal display device was measured every 5 hours in an environment of 25 ° C. and 20% RH. Next, the liquid crystal display device was placed in an environment of 23 ° C. and 80% RH for 5 hours, and the viewing angle of the liquid crystal display device was measured. Finally, the liquid crystal display device was again placed in an environment of 25 ° C. and 55% RH for 5 hours, and the viewing angle of the liquid crystal display device was measured to confirm that the change during the measurement was a reversible fluctuation. These measurements were performed after the liquid crystal display device was placed in the environment for 5 hours. In the viewing angle measurement, the display angle of white display and black display is turned on on the liquid crystal display device, and the angle at which the contrast of 10: 1 can be maintained using the EZ-Contrast 160D manufactured by ELDIM was used as the viewing angle.

From these measurement results, viewing angle deterioration was evaluated according to the following criteria. Evaluation A and B were judged to be a level which is satisfactory practically.

A: No change in viewing angle B: Some change in viewing angle is observed C: A change in viewing angle is observed

As is apparent from Table 5, the polarizing plates 101 to 131 of the present invention, the liquid crystal display devices 101 to 131 including the polarizing plates 201 to 206, and the liquid crystal display devices 201 to 206 are the polarizing plates 132 to 141 of the comparative example. Compared with liquid crystal display devices 132 to 141 using the above, front contrast unevenness is good, and viewing angle variation is small even under conditions where humidity varies. Thus, it can be seen that the liquid crystal display device is extremely stable and excellent in durability.

From the comparison with the results of polarizing plates 132 to 138 using comparative compounds C-001, C-002, C-003, C-004, and C-005, the retardation developer has a specific structure and substituent. Thus, it can be seen that the object of the present invention can be achieved.

The optical film of the present invention has high retardation expression, bleed-out is suppressed, internal haze is low, excellent in brittleness, and in addition, it is an optical film having high light resistance and high humidity and heat resistance. It is preferably used as an optical film of a liquid crystal display device, particularly a polarizing plate protective film having an optical compensation function. Thereby, the front contrast unevenness of the liquid crystal display device can be suppressed and the viewing angle can be improved.

GL slide glass gr Glycerin F Sample film

Claims

An optical film comprising a thermoplastic resin and a compound represented by the following general formula (1).

(In General Formula (1), X 1 represents an oxygen atom or a sulfur atom, Y 1 represents an oxygen atom, a sulfur atom, a nitrogen atom, or NR 41 , and Z 1 represents an oxygen atom, a nitrogen atom, or a sulfur atom. R 11 , R 21 and R 31 represent a substituent, and examples of the substituent represented by R 11 include an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, an aryloxy group, an amino group, and an alkylamino group. , An arylamino group, an alkylthio group, an arylthio group, or a heterocyclic group, and the substituents represented by R 21 and R 31 are an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, and an aryloxy group, respectively. Acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, acylamino group, sulfonyl group, sulfonyloxy Group, an amino group, the substituent is .R 41 to an alkylthio group, or a halogen atom represented by .R 41 represents a hydrogen atom or a substituent, an alkyl group, a cycloalkyl group, an alkyloxy group, an aryl group, Represents an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an alkylthio group, or a halogen atom, k1 represents an integer of 1 to 5, m1 represents an integer of 0 to 4, and n1 represents Represents an integer of 0 to 4. The broken line represents a single bond or a double bond.)
The optical film according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

(In General Formula (2), X 2 represents an oxygen atom or a sulfur atom, Y 2 represents an oxygen atom, a sulfur atom, a nitrogen atom or NR 42 , and Z 2 represents an oxygen atom, a nitrogen atom or a sulfur atom. R 12 and R 22 represent a substituent, R 42 represents a hydrogen atom or a substituent, and the substituents R 12 , R 22 and R 42 are the same as R 11 , R 21 and R 41 in the general formula (1). (M2 represents an integer of 0 to 4. n2 represents an integer of 0 to 4. The broken line represents a single bond or a double bond.)
The optical film according to claim 2, wherein the compound represented by the general formula (2) is a compound represented by the following general formula (3).

(In the general formula (3), R 13 and R 23 represent a substituent. The substituents R 13 and R 23 have the same meanings as R 11 and R 21 in the general formula (1), respectively. M3 represents an integer of 0 to 4.)
The optical film according to claim 3, wherein the compound represented by the general formula (3) is a compound represented by the following general formula (4).

(In the general formula (4), R 14 represents a substituent. The substituent R 14 has the same meaning as R 11 in the general formula (1). K4 represents an integer of 1 to 5.)
The optical film according to any one of claims 1 to 4, wherein the thermoplastic resin contains a cellulose ester.
The optical film according to claim 5, wherein the cellulose ester satisfies both of the following formulas (a) and (b).
Formula (a) 1.5 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
(In the formula, X represents the degree of substitution of the acetyl group. Y represents the degree of substitution of the propionyl group or butyryl group or the total degree of substitution thereof.)
The optical film according to any one of claims 1 to 6, wherein the optical film has a thickness in a range of 20 to 60 µm.
In an environment of 23 ° C. and 55% RH, at a measurement wavelength of 590 nm, the retardation value Ro in the in-plane direction represented by the following formula is in the range of 20 to 150 nm, and the retardation value Rth in the thickness direction is The optical film according to any one of claims 1 to 7, wherein the optical film is in a range of 70 to 350 nm.
Formula (I) Ro = (n x -n y) × d
Formula (II) Rth = {(n x + n y ) / 2−n z } × d
(N x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the optical film, n y is in the plane direction of the optical film, the refractive index in the direction y perpendicular to the direction x , Nz represents the refractive index in the thickness direction z of the optical film, and d (nm) represents the thickness of the optical film.)
A polarizing plate, wherein the optical film according to any one of claims 1 to 8 is provided on at least one surface of a polarizer.
A liquid crystal display device comprising the polarizing plate according to claim 9 on at least one surface of a liquid crystal cell.