WO2010146891A1

WO2010146891A1 - Retardation developer, optical film, polarizing plate using same, and liquid crystal display device

Info

Publication number: WO2010146891A1
Application number: PCT/JP2010/052257
Authority: WO
Inventors: 宏佳木内; 隆嗣鈴木; 潔福坂
Original assignee: コニカミノルタオプト株式会社
Priority date: 2009-06-18
Filing date: 2010-02-16
Publication date: 2010-12-23
Also published as: JP5435030B2; JPWO2010146891A1

Abstract

Disclosed is an optical film which is obtained using a compound that develops a high retardation with a small amount of addition, and which has small fluctuations in retardation due to humidity change and good bleed-out resistance, while being reduced in haze. The optical film is characterized by containing a compound represented by general formula (1). (In the formula, R11, R12 and R13 each represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a heterocyclic group, and at least one of R11, R12 or R13 represents a group containing a cycloalkyl group, an aryl group or a heterocyclic group; R14 and R15 each represents a substituted or unsubstituted methyl group or a group represented by *-CR23=CR22-L2-R21 (wherein * represents the bonding position with a 1,3,5-triazine ring); and L1 and L2 each represents a single bond, -CO-, -COO- or -CONR17-.)

Description

Retardation developer, optical film, polarizing plate using the same, and liquid crystal display device

The present invention relates to a retardation developer, an optical film, a polarizing plate using the same, and a liquid crystal display device.

Resin films such as cellulose ester, polycarbonate, and polyolefin are mainly used for optical compensation films for liquid crystal display devices for optical use. Among them, an optical film having a cellulose ester (hereinafter also simply referred to as a cellulose ester film) is used. It is widely used because of its excellent bonding property to polyvinyl alcohol used in polarizers.

Since the cellulose ester film does not have sufficient birefringence necessary for the optical compensation film as it is, various studies have been made to impart birefringence to the cellulose ester film.

As a method of imparting birefringence to an optical film such as a cellulose ester film, a method of adding a specific compound to an optical film such as a cellulose ester film to develop retardation is known.

For example, Patent Documents 1 and 2 propose a method for obtaining an optical compensation film by adding a 1,3,5-triazine compound. However, although the compounds described in the above-mentioned patent documents show a certain retardation development property, the effect is insufficient, and when a high retardation is required, a large amount of addition is required and haze is increased. There was a problem that it became large or bleed out. Moreover, the problem that it was easy to be influenced by the humidity fluctuation | variation of retardation became clear.

Also, in recent years, development of thin and light notebook PCs and thin and large-screen TVs has progressed, and accordingly, there has been an increasing demand for thinner optical compensation films for liquid crystal display devices. By the way, since the humidity durability of a cellulose-ester film is dependent on the film thickness of a film and is improved by making the film thickness of a film thin, the film thickness reduction is desired. However, since the retardation value decreases when the film thickness is reduced, a compound having even higher retardation is required. As described above, the 1,3,5-triazine-based compounds described in Patent Documents 1 and 2 require a large amount of addition because of insufficient retardation development. The polarizing plate produced using the liquid crystal display device using the polarizing plate was found to be inferior in durability.

As described above, the conventionally known retardation developing agent has insufficient retardation expression, and a compound that exhibits high retardation even when added in a small amount is demanded.

JP 2001-166144 A JP 2003-344655 A

The present invention has been made in view of the above problems. Therefore, an object of the present invention is to provide a compound that exhibits high retardation even when added in a small amount. Another object of the present invention is to provide an optical film using these compounds, in which the variation in retardation humidity is small, the haze is reduced, and the bleedout resistance is good. Furthermore, it is providing the polarizing plate and liquid crystal display device which were excellent in durability using this optical film.

The above object of the present invention is achieved by the following configuration.

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

(In the formula, R ¹¹ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a heterocyclic group. R ¹² represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group. R ¹³ represents a hydrogen atom or a substituent, at least one group of R ¹¹ , R ¹² and R ¹³ represents a group containing a cycloalkyl group, an aryl group or a heterocyclic group, and R ¹⁴ and R ¹⁵ are substituted or An unsubstituted methyl group or a group represented by * —CR ²³ ═CR ²² —L ² —R ²¹ (* represents a bonding position with a 1,3,5-triazine ring) R ²¹ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, .R ²² representing an aryl group or a heterocyclic group represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group R ²³ is .L ¹ and ^{L 2} represent a hydrogen atom or a substituent is a single bond, -CO -, - COO- or -CONR ¹⁷ - be represented ^{.R 14} and ^{R 15} are same, or different When R ¹⁴ or R ¹⁵ represents * -CR ²³ = CR ²² -L ² -R ²¹ , it may be the same as or different from * -CR ¹³ = CR ¹² -L ¹ -R ¹¹ (* Represents the bonding position with the 1,3,5-triazine ring.) R ¹⁷ represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group.)
2. 2. The optical film as described in 1 above, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

(In the formula, R ³¹ , R ³² and R ³³ represent a cycloalkyl group, an aryl group or a heterocyclic group.)
3. 3. The optical film as described in 1 or 2 above, wherein the optical film is an optical film having a cellulose ester.

4. 4. The optical film as described in any one of 1 to 3, wherein the optical film has a thickness of 20 to 60 μm.

5. 5. The optical film as described in any one of 1 to 4 above, wherein retardation Ro represented by the following formula is 20 to 100 nm and Rth is 70 to 300 nm.

Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(However, nx represents the refractive index in the direction x in which the refractive index is maximum in the in-plane direction of the optical film, and ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the optical film. , Nz represents the refractive index in the thickness direction z of the optical film, and d (nm) represents the thickness of the optical film.)
6). 6. A polarizing plate comprising the optical film according to any one of 1 to 5 on at least one surface of a polarizer.

7. 7. A liquid crystal display device comprising the polarizing plate according to 6 on at least one surface of a liquid crystal cell.

8. Retardation expression agent characterized by being represented by the following general formula (1).

(In the formula, R ¹¹ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a heterocyclic group. R ¹² represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group. R ¹³ represents a hydrogen atom or a substituent, and at least one group of R ¹¹ , R ¹² and R ¹³ includes a cycloalkyl group, an aryl group or a heterocyclic group, and R ¹⁴ and R ¹⁵ are substituted or unsubstituted. A methyl group or a group represented by * —CR ²³ ═CR ²² —L ² —R ²¹ (* represents a bonding position with a 1,3,5-triazine ring), where R ²¹ represents a hydrogen atom; , alkyl group, cycloalkyl group, alkenyl group, an aryl group or a heterocyclic group .R ²² is a hydrogen atom, an alkyl group, .R a cycloalkyl group, an aryl group or a heterocyclic group ²³ Represents a hydrogen atom or a substituent, L ¹ and L ² represent a single bond, —CO—, —COO—, or —CONR ¹⁷ —, and R ¹⁴ and R ¹⁵ may be the same or different. , R ¹⁴ or R ¹⁵ represents * -CR ²³ = CR ²² -L ² -R ²¹ , it may be the same as or different from * -CR ¹³ = CR ¹² -L ¹ -R ¹¹ ( (* Represents a bonding position with the 1,3,5-triazine ring.) R ¹⁷ represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group.)

According to the present invention, it was possible to provide a compound that exhibits high retardation with a small amount of addition. Moreover, using these compounds, it was possible to provide an optical film having a small retardation humidity variation, a reduced haze, and good bleedout resistance. Furthermore, using the optical film, a polarizing plate and a liquid crystal display device excellent in durability could be provided.

Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

As a result of intensive studies on an optical film such as a cellulose ester film containing a retardation developer that can solve the above-mentioned problems, the detailed reason has not been elucidated, but a 1,3,5-triazine having a specific alkenyl group It has been found that an optical film having a high retardation expression with a small amount of addition, a small variation in retardation humidity, a reduced haze, and a bleedout resistance can be obtained by using a system compound. It was. Moreover, when the obtained optical film was used, it discovered that the polarizing plate and liquid crystal display device excellent in durability were obtained.

Specifically, as a result of intensive studies, the present inventors have used 1,3,5-triazine compounds substituted with a specific ethenyl group containing a cycloalkyl group, an aryl group or a heterocyclic ring as a retardation developer. In this case, the present inventors have found that the above problems can be solved and have reached the present invention.

(Retardation expression agent represented by general formula (1))
Next, the compound represented by the general formula (1) of the present invention will be described in detail.

In the general formula (1), R ¹¹ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, or a heterocyclic group. Examples of the alkyl group represented by R ¹¹ include methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group and the like. Can do. Examples of the cycloalkyl group represented by R ¹¹ include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, and the like. Examples of the alkenyl group represented by R ¹¹ include vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, and 4-hexenyl group. Group, cyclohexenyl group and the like. Examples of the aryl group represented by R ¹¹ include a phenyl group and a naphthyl group. Examples of the heterocyclic group represented by R ¹¹ include a pyridyl group, a thiazolyl group, an oxazolyl group, a pyrazolyl group, an imidazolyl group, a furyl group, a thienyl group, and a pyrrolyl group. The alkyl group, cycloalkyl group, alkenyl group, aryl group or heterocyclic group represented by R ¹¹ may have a substituent, and the substituent is not particularly limited. The group similar to the substituent represented by R < ¹³ > of Formula (1) can be mentioned.

In the general formula (1), R ¹² represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group. When R ¹² represents an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group, these groups include an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group represented by R ^{11 in the} general formula (1). Examples of the same groups as those described above can be given. The alkyl group, cycloalkyl group, aryl group or heterocyclic group represented by R ¹² may have a substituent, and the substituent is not particularly limited. For example, the general formula (1) described below can be used. It includes the same groups as the substituents represented by R ¹³ in).

In the general formula (1), R ¹³ represents a hydrogen atom or a substituent. When R ¹³ represents a substituent, although there is no particular limitation on the substituent represented by R ^13, for example, an alkyl group (e.g., methyl group, an ethyl group, a propyl group, an isopropyl group, t- butyl group, a 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.) ), Acylamino groups (for example, acetylamino group, benzoylamino group, etc.), alkylthio groups (for example, methylthio group, ethylthio group, etc.), arylthio groups (for example, phenylthio group, naphthylthio group, etc.), alkenyl groups (for example, vinyl group) 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, -Pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom etc.), alkynyl group (eg, propargyl group) Etc.), heterocyclic groups (eg, pyridyl group, thiazolyl group, oxazolyl group, pyrazolyl group, imidazolyl group, furyl group, thienyl group, pyrrolyl group, etc.), alkylsulfonyl groups (eg, methylsulfonyl group, ethylsulfonyl group, etc.) Arylsulfonyl groups (eg, phenylsulfonyl group, naphthylsulfonyl group, etc.), alkylsulfinyl groups (eg, methylsulfinyl group, etc.), arylsulfinyl groups (eg, phenylsulfinyl group, etc.), phosphono groups, acyl groups (eg, acetyl) Group, pivaloyl group, benzoyl group, etc.) Carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group) Group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylamino Sulfonyl groups, etc.), sulfonamide groups (eg methanesulfonamide groups, benzenesulfonamide groups etc.), cyano groups, alkoxy groups (eg Methoxy group, ethoxy group, propoxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), heterocyclic oxy group, siloxy group, acyloxy group (eg acetyloxy group, benzoyloxy group etc.) Sulfonic acid group, sulfonic acid salt, aminocarbonyloxy group, amino group (for example, 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, octyl Raid group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido 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.), heterocyclic thio group, thioureido group, carboxyl group, carboxylic acid salt, hydroxyl group, mercapto group, nitro group, etc. Each group is mentioned. These substituents may be further substituted with the same substituent.

In the general formula (1), at least one group of R ¹¹ , R ¹² and R ¹³ represents a group containing a cycloalkyl group, an aryl group or a heterocyclic group. Specifically, at least one group of R ¹¹ , R ¹² and R ¹³ may be a cycloalkyl group, an aryl group or a heterocyclic group, and is a group containing a cycloalkyl group, an aryl group or a heterocyclic group. May be.

In the general formula (1), R ¹¹ is preferably a cycloalkyl group, an aryl group or a heterocyclic group, and more preferably an aryl group or a heterocyclic group.

In the general formula (1), R ¹² and R ¹³ are preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

In the general formula (1), R ¹⁴ and R ¹⁵ represent a substituted or unsubstituted methyl group, or a group represented by * -CR ²³ = CR ²² -L ² -R ²¹ (* represents 1, 3, Represents the bonding position with the 5-triazine ring).

When R ¹⁴ and R ¹⁵ represent a substituted methyl group, the substituent that the methyl group may have is not particularly limited. For example, the substituent represented by R ¹³ in the general formula (1) Similar groups can be mentioned.

R ²¹ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a heterocyclic group. When R ²¹ represents an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a heterocyclic group, these groups include an alkyl group, a cycloalkyl group, an alkenyl group represented by R ^{11 in the} general formula (1), Examples of the aryl group or heterocyclic group include the same groups as those described above. The alkyl group, cycloalkyl group, alkenyl group, aryl group or heterocyclic group represented by R ²¹ may have a substituent, and the substituent is not particularly limited. For example, the general formula (1) The same group as the substituent represented by R < ¹³ > of can be mentioned.

R ²² represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group. When R ²¹ represents an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group, these groups include an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group represented by R ^{11 in the} general formula (1). Examples of the same groups as those described above can be given. The alkyl group, cycloalkyl group, aryl group or heterocyclic group represented by R ²² may have a substituent, and the substituent is not particularly limited. For example, R ^{13 in the} general formula (1) The group similar to the substituent represented by can be mentioned.

R ²³ represents a hydrogen atom or a substituent. When R ²³ represents a substituent, the substituent is not particularly limited, and examples thereof include the same groups as the substituent represented by R ¹³ in the general formula (1).

In the general formula (1), R ²¹ is preferably a cycloalkyl group, an aryl group, or a heterocyclic group, and more preferably an aryl group or a heterocyclic group.

In the general formula (1), R ²² and R ²³ are preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

In the general formula (1), R ¹⁴ and R ¹⁵ may be the same or different, and when R ¹⁴ or R ¹⁵ represents * -CR ²³ = CR ²² -L ² -R ²¹ , * —CR ¹³ ═CR ¹² —L ¹ —R ¹¹ may be the same or different (* represents the bonding position with the 1,3,5-triazine ring).

In the general formula (1), R ¹⁴ or R ¹⁵ is preferably a substituent represented by * -CR ²³ = CR ²² -L ² -R ²¹ , and R ¹⁴ and R ¹⁵ are * -CR ²³ = A substituent represented by CR ²² -L ² -R ²¹ is more preferred (* represents a bonding position with a 1,3,5-triazine ring).

In the general formula (1), when R ¹⁴ and R ¹⁵ represent * -CR ²³ = CR ²² -L ² -R ²¹ , these groups are the same as * -CR ¹³ = CR ¹² -L ¹ -R ¹¹ (* Represents the bonding position with the 1,3,5-triazine ring).

In the general formula (1), L ¹ and L ² represent a single bond, —CO—, —COO—, or —CONR ¹⁷ —.

R ¹⁷ represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group. When R ¹⁷ represents an alkyl group, a cycloalkyl group or an aryl group, these groups are the same as the groups described as examples of the alkyl group, cycloalkyl group or aryl group represented by R ^{11 in the} general formula (1). Can be mentioned. The alkyl group, cycloalkyl group or aryl group represented by R ¹⁷ may have a substituent, and the substituent is not particularly limited. For example, the substituent is represented by R ¹³ in the general formula (1). The same group as a substituent can be mentioned.

In the general formula (1), L ¹ and L ² are preferably single bonds.

(Retardation expression agent represented by the general formula (2))
Next, the compound represented by the general formula (2) of the present invention will be described in detail.

In the general formula ^{^{(2), R 31, R}} 32, R 33 represents a cycloalkyl group, an aryl group or a heterocyclic group. Examples of these groups include the same groups as those described as examples of the cycloalkyl group, aryl group or heterocyclic group represented by R ^{11 in the} general formula (1). The cycloalkyl group, aryl group or heterocyclic group represented by R ³¹ , R ³² and R ³³ may have a substituent, and the substituent is not particularly limited. For example, the general formula (1) The same group as the substituent represented by R < ¹³ > of can be mentioned. R ³¹ , R ³² and R ³³ are preferably an aryl group or a heterocyclic group. The compound represented by the general formula (1) is preferably a compound represented by the general formula (2).

Specific examples of the compound represented by the general formula (1) are shown below, but the present invention is not limited thereto. For the sake of convenience, specific examples of the compounds are described by distinguishing between E-form and Z-form, but are not limited thereto.

These compounds can be produced by known methods.

Hereinafter, the method for synthesizing the compound according to the present invention will be described in detail, but the present invention is not limited thereto.

(Synthesis of Exemplified Compound 14)
1,3,5-trimethyltriazine 5 g and potassium hydroxide 6.9 g were dissolved in 50 ml of methanol. Benzaldehyde 13g was added, and it heated and refluxed for 6 hours. The reaction solution was cooled to 5 ° C., filtered, and washed with cooled methanol. Recrystallization from a dichloromethane-methanol mixed solvent gave Exemplified Compound 14 (13.4 g).

(Synthesis of Exemplary Compound 34)
1,3,5-trimethyltriazine 5 g and potassium hydroxide 6.9 g were dissolved in 50 ml of methanol. 13.7 g of benzaldehyde was added, and the mixture was heated to reflux for 6 hours. The reaction solution was cooled to 5 ° C., filtered, and washed with cooled methanol. Recrystallization from a dichloromethane-methanol mixed solvent gave Exemplified Compound 34 (14 g).

(Synthesis of Exemplary Compound 42)
1,3,5-Triethyltriazine (5 g) and potassium hydroxide (5.1 g) were dissolved in methanol (50 ml). 1-2.4 g of p-methoxybenzaldehyde was added, and it heated and refluxed for 6 hours. The reaction solution was cooled to 5 ° C., filtered, and washed with cooled methanol. Recrystallization from a dichloromethane-methanol mixed solvent gave Exemplified Compound 42 (13.8 g).

(Synthesis of Exemplary Compound 50)
1,3,5-Trimethyltriazine (5 g) and potassium hydroxide (6.9 g) were dissolved in isopropanol (50 ml). 23 g of benzophenone was added, and the mixture was heated to reflux for 12 hours. The reaction solution was cooled to 5 ° C., filtered, and washed with cooled methanol. Recrystallization was performed with a dichloromethane-methanol mixed solvent to obtain Exemplary Compound 50 (17.5 g).

The above-mentioned compounds having a 1,3,5-trimethyltriazine structure such as 1,3,5-trimethyltriazine and 1,3,5-triethyltriazine can be produced, for example, by known methods described in the following documents 1 and 2.

Reference 1: The Journal of Organic Chemistry, 1961, 26 (8), 2778
Reference 2: SYNTHESIS, 2004, no. 4,503
The retardation developing agent represented by the general formula (1) according to the present invention can be contained by appropriately adjusting the amount for imparting the desired retardation, but the addition amount is relative to the resin used. The content is preferably 1 to 15% by mass, and particularly preferably 2 to 10% by mass. If it exists in this range, sufficient retardation can be provided to the cellulose ester of this invention, and it is preferable.

(Optical film)
In the present invention, the “optical film” is a functional film used for various display devices such as a liquid crystal display, a plasma display, and an organic EL display, and more specifically, a polarizing plate protective film and a retardation film for a liquid crystal display device. , An antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, an optical compensation film for expanding the viewing angle, and the like.

As the resin used for the resin film which is the base material of the optical film of the present invention, in addition to the cellulose ester resin alone or the cellulose ester resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyester resin, Polyarylate resins, acrylic resins (including copolymers), olefin resins (norbornene resins, cyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, etc.), cellulose ether resins And resins using a combination of resins such as vinyl resins (including polyvinyl acetate resins and polyvinyl alcohol resins). Among these, a cellulose ester resin alone or a cellulose ester resin combined with an acrylic resin is preferable.

(Cellulose ester)
The cellulose ester used in the cellulose ester resin film according to the present invention is not particularly limited, but the ester group is preferably a linear or branched carboxylic acid ester having about 2 to 22 carbon atoms. Or an ester of an aromatic carboxylic acid. In addition, these carboxylic acids may have a substituent. The cellulose ester is particularly preferably a lower fatty acid ester having 6 or less carbon atoms.

As preferred cellulose esters, specifically, cellulose esters include, in addition to cellulose acetate, propionate groups other than acetyl groups such as cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate. Examples include mixed fatty acid esters of cellulose to which butyrate groups are bonded.

Preferred cellulose esters used in the present invention preferably satisfy the following formulas (a) and (b).

Formula (a) 2.0 ≦ X + Y ≦ 3.0
Formula (b) 0 ≦ Y ≦ 1.5
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 a mixture thereof.

Of these, cellulose acetate (Y = 0) and cellulose propionate (Y; propionyl group, Y> 0) are most preferably used. Cellulose acetate propionate satisfies 1.0 ≦ X ≦ 2.5, preferably 0.1 ≦ Y ≦ 1.5, and 2.0 ≦ X + Y ≦ 3.0. The method for measuring the substitution degree of the acyl group can be measured according to ASTM-D817-96.

Also, in order to obtain optical properties that meet the purpose, resins having different degrees of substitution may be mixed and used. The mixing ratio is preferably 10:90 to 90:10 (mass ratio).

The number average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000, and the resulting film is preferably strong in mechanical strength. Furthermore, 70,000-200000 are preferably used.

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 cellulose used as a raw material of the cellulose ester used in the present invention 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 used in the present invention can be produced by a known method. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

(acrylic resin)
The acrylic resin used in combination with the cellulose ester resin is not particularly limited, but comprises 50 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of other monomer units copolymerizable therewith. Those are preferred.

Other monomers that can be copolymerized include alkyl methacrylates having 2 to 18 alkyl carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, acrylic acid, methacrylic acid, and other α, β-insoluble monomers. Unsaturated group-containing divalent carboxylic acids such as saturated acid, maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, Examples thereof include maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride and the like, and these can be used alone or in combination of two or more monomers.

Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

The acrylic resin used in the optical film of the present invention has a weight average molecular weight (Mw) of 110,000, particularly from the viewpoint of improving brittleness as an optical film and improving transparency when compatible with a cellulose ester resin. It is preferable that it is 1,000,000 or less.

When the weight average molecular weight (Mw) of the acrylic resin is 110,000 or more, sufficient brittleness improvement can be obtained and the compatibility with the cellulose ester resin is excellent. The weight average molecular weight (Mw) of the acrylic resin is more preferably in the range of 110,000 to 600,000, and particularly preferably in the range of 110,000 to 400,000.

The weight average molecular weight of the acrylic resin used in the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
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 Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

The production method of the acrylic resin in the present invention is not particularly limited, and any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used.

The polymerization temperature may be 30 to 100 ° C. for suspension or emulsion polymerization, and 80 to 160 ° C. for bulk or solution polymerization. In order to control the reduced viscosity of the obtained copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

As the acrylic resin according to the present invention, commercially available resins can also be used. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Denki Kagaku Kogyo Co., Ltd.) and the like can be mentioned. . Two or more acrylic resins can be used in combination.

In addition to the compound represented by the general formula (1), the optical film of the present invention contains at least one of a sugar ester compound, a plasticizer, an ultraviolet absorber, an antioxidant, and fine particles described below. It may be added.

(Sugar ester compound)
Examples of the sugar ester compound include ester compounds in which at least one pyranose structure or furanose structure is 1 to 12 and all or part of the OH groups in the structure are esterified.

The proportion of esterification is preferably 70% or more of the OH groups present in the pyranose structure or furanose structure.

Examples of the sugar as a raw material for synthesizing the sugar ester compound of the present invention include the following, but the present invention is not limited to these.

Glucose, galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .

Other examples include gentiobiose, gentiotriose, gentiotetraose, xylotriose, and galactosyl sucrose.

Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable.

Examples include sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, and more preferably sucrose.

The monocarboxylic acid used for esterifying all or part of the OH groups in the pyranose structure or furanose structure of the present invention is not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, An aromatic monocarboxylic acid or the like can be used. The carboxylic acid used may be one type or a mixture of two or more types.

Preferred aliphatic monocarboxylic acids 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 , Saturated fatty acids such as 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, melicic acid, and laccelic acid, Examples include 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 acids include acetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

Examples of preferred aromatic monocarboxylic acids include aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, and naphthalene. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralin carboxylic acid, or derivatives thereof. More specifically, xylyl acid, hemelic acid, mesitylene acid, prenylic acid, γ-isoduric acid, jurylic acid, mesitic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropic 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-pyro Technic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratromic acid, o-veratrumic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratrumic acid, o-homoveratrumic acid, phthalonic acid, p- Although coumaric acid can be mentioned, benzoic acid is particularly preferable.

Oligosaccharide ester compounds can be applied as compounds having 1 to 12 at least one of the pyranose structural units or furanose structural units according to the present invention.

Oligosaccharides are produced by allowing an enzyme such as amylase to act on starch, sucrose, etc. Examples of oligosaccharides that can be applied to the present invention include maltooligosaccharides, isomaltooligosaccharides, fructooligosaccharides, galactooligosaccharides, and xylooligos. Sugar.

Hereinafter, examples of the sugar ester compound are listed below, but the present invention is not limited thereto.

Monopet SB: manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Monopet SOA: manufactured by Daiichi Kogyo Seiyaku Co., Ltd. The sugar ester compound is preferably added in an amount of 0.5 to 30% by mass based on the resin used. Is preferably contained in an amount of 5 to 20% by mass.

(Plasticizer)
The optical film of the present invention can 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. It is selected from plasticizers, acrylic plasticizers and the like. Of these, when two or more plasticizers are used, at least one plasticizer is preferably a polyhydric alcohol ester plasticizer.

The polyhydric alcohol ester plasticizer is a plasticizer composed of an ester of a divalent 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 preferably used in the present invention is represented by the following general formula (a).

Formula (a) Ra- (OH) _n
(However, Ra represents an n-valent organic group, n represents a positive integer of 2 or more, and an OH group represents an alcoholic and / or phenolic hydroxyl group.)
Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. 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 Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

Preferred examples of the monocarboxylic acid include the following, but the present invention is not limited to this.

As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. 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 cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and 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, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.

The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 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 cellulose ester.

The carboxylic acid used in the polyhydric alcohol ester may be one kind or a mixture 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 glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be 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 glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

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, and dicyclohexyl terephthalate.

Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

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.

The polyvalent carboxylic acid ester compound is composed of an ester of a divalent or higher, preferably a divalent to 20valent 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
(Where Rb is an (m + n) -valent organic group, m is a positive integer of 2 or more and 6 or less, n is an integer of 0 or more and 4 or less, a COOH group is a carboxyl group, and an OH group is an alcoholic or phenolic hydroxyl group. Represents.)
Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these. Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

The alcohol used in the polyvalent carboxylic acid ester compound that can be used in the present invention is not particularly limited, and known alcohols and phenols can be used. For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. 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.

When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxyl group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

As the aliphatic monocarboxylic acid, a straight-chain or side-chain fatty acid having 1 to 32 carbon atoms can be preferably used. 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 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 biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. Aromatic monocarboxylic acids having a ring of Of these monocarboxylic acids, acetic acid, propionic acid, and benzoic acid are particularly preferable.

The molecular weight of the polyvalent carboxylic acid ester compound 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 retention, and the smaller one is preferable in terms of moisture permeability and compatibility with the cellulose ester.

The alcohol used for the polyvalent carboxylic acid ester that can be used in the present invention may be one kind or a mixture of two or more kinds.

The acid value of the polyvalent carboxylic acid ester compound that can be used in the present invention 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.

(Acid value)
The acid value means the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto. For example, 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, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

The polyester plasticizer is not particularly limited, and a polyester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be used. Although it does not specifically limit as a polyester plasticizer, For example, the aromatic terminal ester plasticizer represented by the following general formula (c) can be used.

Formula (c)
B—COO — ((G—O—) _m —CO—A—COO—) _n G—O—CO—B
In the formula, B represents a benzene ring, and may have another substituent. G represents an alkylene group having 2 to 12 carbon atoms or an arylene group having 6 to 12 carbon atoms, A represents an alkylene group having 2 to 10 carbon atoms or an arylene group having 6 to 12 carbon atoms, and m and n are repeating units. Represents.

The compound of the general formula (c) is represented by benzene monocarboxylic acid represented by BCOOH, alkylene glycol or oxyalkylene glycol or aryl glycol represented by HO— (GO) _m —H, and represented by HOCO-A-COOH. It is synthesized from an alkylene dicarboxylic acid or arylene dicarboxylic acid and can be obtained by a reaction similar to that of a normal polyester plasticizer.

Examples of the benzene monocarboxylic acid component of the aromatic terminal ester plasticizer used in the present invention include, for example, benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethyl There are benzoic acid, normal propyl benzoic acid, aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

Examples of the alkylene glycol component having 2 to 12 carbon atoms as the raw material of the aromatic terminal ester plasticizer that can be used in the present invention 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-1,3propanediol (3,3 -Dimethylolheptane), 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl , 3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc. These glycols are used as one or a mixture of two or more. 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 as the raw material for the aromatic terminal ester plasticizer include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. These glycols can be used as one or a mixture of two or more.

Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms as the raw material for the aromatic terminal ester plasticizer include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, etc. These are each used as one or a mixture of two 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 aromatic terminal ester plasticizer used in the present invention is preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

Hereinafter, synthesis examples of aromatic terminal ester plasticizers that can be used in the present invention will be shown.

<Sample No. 1 (Aromatic terminal ester sample)>
A reaction vessel was charged with 410 parts of phthalic acid, 610 parts of benzoic acid, 737 parts of dipropylene glycol, and 0.40 part of tetraisopropyl titanate as a catalyst. While the monohydric alcohol was refluxed, heating was continued at 130 to 250 ° C. until the acid value became 2 or less, and water produced was continuously removed. Next, the distillate is removed at 200 to 230 ° C. under reduced pressure of 1.33 × 10 ⁴ Pa to finally 4 × 10 ² Pa or less, and then filtered to remove an aromatic terminal ester plastic having the following properties: An agent was obtained.

Viscosity (25 ° C., mPa · s); 43400
Acid value: 0.2
<Sample No. 2 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 341 parts of ethylene glycol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 31000
Acid value: 0.1
<Sample No. 3 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,2-propanediol, and 0.35 part of tetraisopropyl titanate as the catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 38000
Acid value: 0.05
<Sample No. 4 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,3-propanediol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 37000
Acid value: 0.05
(Acrylic polymer)
The optical film according to the present invention can also contain a (meth) acrylic polymer as a plasticizer.

The (meth) acrylic polymer is preferably 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.

As the (meth) acrylic polymer, at least an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxyl group in the molecule and an ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydroxyl group are used. The polymer X having a weight average molecular weight of 3000 to 30000 obtained by polymerization and the polymer Y having a weight average molecular weight of 500 to 3000 obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring More preferably, it is a mixture.

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

Formula (X)
-[Xa] _m- [Xb] _n- [Xc] _p-
In the formula, Xa = — [CH ₂ —C (Rc) (CO ₂ Rd)] — and Xb = — [CH ₂ —C (Re) (CO ₂ Rf—OH)] — are represented.

General formula (Y)
Ry- [Ya] _k- [Yb] _q-
In the formula, Ya = — [CH ₂ —C (Rg) (CO ₂ Rh—OH)] — is represented.

Rc, Re and Rg represent H or CH ₃ . 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 OH, 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, and k ≠ 0.

The amount of these plasticizers added is preferably 0.5 to 30% by mass, particularly 5 to 20% by mass, based on the resin used.

(UV absorber)
The optical film according to the present invention can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet light having a wavelength of 400 nm or less. Particularly, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, particularly Preferably it is 2% or less.

Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.

For example, 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, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, There are tinuvins such as tinuvin 928, all of which are commercially available from Ciba Japan and can be preferably used.

The UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. .

In addition, a discotic compound such as a compound having a 1,3,5-triazine ring is also preferably used as the ultraviolet absorber.

The optical film according to the present invention preferably contains two or more kinds of ultraviolet absorbers.

Also, as the ultraviolet absorber, a polymeric ultraviolet absorber can be preferably used, and in particular, a polymer type ultraviolet absorber described in JP-A-6-148430 is preferably used.

The method of adding the UV absorber can be added to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane or a mixed solvent thereof. Or you may add directly in dope composition.

For inorganic powders that do not dissolve in organic solvents, use a dissolver or sand mill in the organic solvent and cellulose ester to disperse them before adding them to the dope.

The amount of the UV absorber used is not uniform depending on the type of UV absorber, the operating conditions, etc., but when the dry film thickness of the polarizing plate protective film is 30 to 200 μm, the amount used is 0.5 to the polarizing plate protective film. Is preferably 10 to 10% by mass, and more preferably 0.6 to 4% by mass.

(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 has a role of delaying or preventing the optical film from being decomposed by, for example, the residual solvent amount of halogen in the optical film or phosphoric acid of the phosphoric acid plasticizer. It is preferable to contain.

As such an antioxidant, a hindered phenol compound is preferably used. For example, 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], oct Decyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-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-hydroxy Benzyl) -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. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

The amount of these compounds added is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio based on the resin used.

(Fine particles)
The optical film according to the present invention preferably contains fine particles.

As fine particles used in the present invention, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated silicic acid. Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate. Further, fine particles of an organic compound can also be preferably used. Examples of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, melamine resin Also, pulverized and classified products of organic polymer compounds such as polyolefin-based powders, polyester-based resins, polyamide-based resins, polyimide-based resins, polyfluorinated ethylene-based resins, and starches. Alternatively, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray dry method or a dispersion method, or an inorganic compound can be used.

Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

The average primary particle size of the fine particles is preferably 5 to 400 nm, more preferably 10 to 300 nm.

These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable.

The content of these fine particles in the polarizing plate protective film is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass. In the case of a polarizing plate protective film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the 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.). it can.

Zirconium oxide fine particles are commercially available under the trade names of Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of the polymer 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 and can be used.

Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the turbidity of the polarizing plate protective film low. In the polarizing plate protective film used in the present invention, it is preferable that the dynamic friction coefficient of at least one surface is 0.2 to 1.0.

Various additives may be batch-added to the dope that is a 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 dissolve a small amount of resin in order to improve mixing with the dope. The amount of the resin is preferably 1 to 10 parts by mass, more preferably 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer) or the like is preferably used.

(Production method)
Next, the manufacturing method of the optical film which concerns on this invention is demonstrated.

The optical film according to the present invention can be preferably used regardless of whether it is a film produced by a solution casting method or a film produced by a melt casting method.

The production of the optical film according to the present invention includes a step of preparing a dope by dissolving a resin and an additive in a solvent, a step of casting the dope on an endless metal support that moves indefinitely, a web of the cast dope As a drying process, a peeling process from a metal support, a stretching or width holding process, a further drying process, and a winding process of a finished film.

The process for preparing the dope will be described. The concentration of the resin in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of the resin is too high, the load during filtration increases and the filtration accuracy deteriorates. The concentration for achieving both of these is preferably 10 to 35% by mass, and more preferably 15 to 25% by mass.

The solvent used in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of the resin in terms of production efficiency, and there are many good solvents. Is preferable from the viewpoint of the solubility of the resin. The 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. With a good solvent and a poor solvent, what melt | dissolves the resin to be used independently is defined as a good solvent, and a solvent that swells or does not dissolve alone is defined as a poor solvent. For example, when cellulose ester is used as the resin, depending on the average degree of acetylation (acetyl group substitution degree), the good solvent and the poor solvent change, and the good solvent and the poor solvent change. For example, when acetone is used as the solvent, Acetic acid ester (acetyl group substitution degree 2.4) and cellulose acetate propionate are good solvents, and cellulose acetate ester (acetyl group substitution degree 2.8) is a poor solvent.

The good solvent used in the present invention is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.

The poor solvent used in the present invention is not particularly limited, but for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like are preferably used. The dope preferably contains 0.01 to 2% by mass of water. Moreover, the solvent used for melt | dissolution of a cellulose ester collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again. The recovery solvent may contain trace amounts of additives added to the cellulose ester, such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.

A general method can be used as a method for dissolving the resin when preparing the dope described above. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and does not boil under pressure, in order to prevent the formation of massive undissolved material called gel or mamako. Moreover, after mixing resin with a poor solvent and making it wet or swell, the method of adding a good solvent and melt | dissolving is also used preferably.

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. For example, a jacket type is preferable because temperature control is easy.

The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the resin, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. The preferred heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and particularly preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

Alternatively, a cooling dissolution method is also preferably used, whereby the resin can be dissolved in a solvent such as methyl acetate.

Next, the solution in which this resin is dissolved is filtered using an appropriate filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is particularly preferable.

There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material resin by filtration.

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

The dope can be filtered by a normal method, but the method of filtering while heating 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 the filtration pressure before and after filtration. The expression of the difference (referred to as differential pressure) is small and preferable. A preferred temperature is 45 to 120 ° C., more preferably 45 to 70 ° C., and particularly preferably 45 to 55 ° C.

A smaller filtration pressure is preferable. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and particularly preferably 1.0 MPa or less.

Here, the dope casting will be described.

The metal support in the casting process is preferably a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to less than the boiling point of the solvent, and a higher temperature is preferable because the web drying speed can be increased. May deteriorate. The support temperature is preferably 0 to 40 ° C, more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and 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 for the optical film to exhibit good flatness, the amount of residual solvent when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. And particularly preferably 20 to 30% by mass or 70 to 120% by mass.

In the present invention, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

In the drying step of the optical film, the web is peeled off from the metal support, and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less. The content is preferably 0 to 0.01% by mass or less.

In the film drying process, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

In order to produce the optical film used in the present invention, it is particularly preferable to stretch in the width direction (lateral direction) by a tenter method in which both ends of the web are gripped by clips or the like. Peeling is preferably performed at a peeling tension of 300 N / m or less.

The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but is preferably performed with hot air from the viewpoint of simplicity.

It is preferable that the drying temperature in the web drying process is increased stepwise from 40 to 200 ° C.

The film thickness of the optical film is not particularly limited, but 10 to 200 μm is used. In particular, the film thickness is preferably 10 to 100 μm. More preferably, it is 20 to 60 μm.

The optical film according to the present invention has a width of 1 to 4 m. Particularly, those having a width of 1.4 to 4 m are preferably used, and particularly preferably 1.6 to 3 m. If it exceeds 4 m, conveyance becomes difficult.

(Stretching operation, refractive index control)
In the step of producing the optical film according to the present invention, it is preferable to perform refractive index control, that is, retardation control by a stretching operation.

For example, biaxial stretching or uniaxial stretching can be performed sequentially or simultaneously with respect to the longitudinal direction (film forming direction) of the film and the direction orthogonal to the longitudinal direction of the film, that is, the width direction. Simultaneous biaxial stretching includes stretching in one direction and stretching the other while relaxing the tension.

The draw ratios in the biaxial directions perpendicular to each other are preferably in the range of 0.8 to 1.5 times in the casting direction and 1.1 to 2.5 times in the width direction, respectively. It is preferable to carry out in the range of 0.9 to 1.0 times in the direction and 1.2 to 2.0 times in the width direction.

The stretching temperature is preferably 120 ° C. to 200 ° C., more preferably 140 ° C. to 180 ° C.

The residual solvent in the film at the time of stretching is preferably 20 to 0%, more preferably 15 to 0%.

There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the 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. Of course, these methods may be used in combination. In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because 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.

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

When the optical film according to the present invention is used in the VA mode (a mode in which vertically aligned liquid crystal is used), either one of two on each side of the cell (two-sheet type) or one above or below the cell. You may use for any form (single sheet type) used only for one side.

The optical film according to the present invention has an in-plane retardation Ro represented by the following formula of 23 ° C. and 55% RH, a wavelength of 20 to 100 nm at a wavelength of 590 nm, and a thickness direction retardation Rth of 23 ° C. and 55 In an environment of% RH, the wavelength is preferably 70 to 300 nm at 590 nm.

Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
However, nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the optical film, ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the optical film, nz represents the refractive index in the thickness direction z of the optical film, and d (nm) represents the thickness of the optical film.

These retardation values can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).

When the slow axis or the fast axis of the optical film according to the present invention exists in the film plane and the angle formed by the slow axis or the fast axis and the film forming direction is θ1, θ1 is −1 ° or more and + 1 °. Or less, more preferably −0.5 ° or more and + 0.5 ° or less. This θ1 can be defined as an orientation angle, and the measurement of θ1 can be performed using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). Each of θ1 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in a color liquid crystal display device.

(Physical properties)
The moisture permeability of the optical film according to the present invention is preferably 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.

The optical film according to the present invention preferably has a breaking elongation of 10 to 80%.

The visible light transmittance of the optical film according to the present invention is preferably 90% or more, and more preferably 93% or more.

The haze of the optical film according to the present invention is preferably less than 1%, particularly preferably 0 to 0.1%.

Further, a retardation value over a wider range can be obtained by further applying a liquid crystal layer or a resin layer to the optical film according to the present invention, or by further stretching it.

(Polarizer)
The optical film which concerns on this invention can be used for the polarizing plate which used the polarizing plate protective film, and the liquid crystal display device of this invention using the same. The optical film according to the present invention is preferably a film that also functions as a polarizing plate protective film. In that case, it is not necessary to prepare an optical film having a phase difference separately from the polarizing plate protective film. The manufacturing process can be simplified by reducing the thickness of the apparatus.

In the liquid crystal display device of the present invention, the polarizing plate according to the present invention is preferably bonded to both surfaces of the liquid crystal cell via an adhesive layer.

The polarizing plate according to the present invention can be produced by a general method. The optical film according to the present invention is preferably bonded to at least one surface of a polarizer prepared by subjecting the polarizer side of the optical film to alkali saponification treatment and immersion drawing in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. Another polarizing plate protective film can be bonded to the other surface. When the optical film according to the present invention is a liquid crystal display device, it is preferably provided on the liquid crystal cell side of the polarizer, and a conventional polarizing plate protective film can be used as the film outside the polarizer.

For example, as a conventional polarizing plate protective film, a commercially available cellulose ester film (for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE-HA, KC8UY-HA, HAC KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are preferably used.

The polarizing plate protective film used on the surface side of the display device 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.

A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed.

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

(Liquid crystal display device)
By using the polarizing plate using the optical film of the present invention for a liquid crystal display device, various liquid crystal display devices of the present invention having excellent visibility can be produced.

The optical film and polarizing plate of the present invention can be used in 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 a large-screen liquid crystal display device having a 30-inch or larger screen can reduce coloration during black display due to light leakage and can provide a liquid crystal display device with excellent visibility such as front contrast.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
<Production of Cellulose Ester Film 101>
<Fine particle dispersion 1>
Aerosil R972V
(Silica fine particles; primary particle size 16 nm; manufactured by Nippon Aerosil Co., Ltd.)
11 parts by mass Ethanol 89 parts by mass The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
With the following composition, the fine particle dispersion 1 was slowly added to a dissolution tank containing methylene chloride while sufficiently stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope solution 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. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Preparation of main dope solution>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose ester A
(Cellulose triacetate with an acetyl substitution degree of 2.90;
100 mass parts Retardation expression agent: Exemplified compound 14 3 mass parts Monopet SB
(Sucrose benzoate; sugar ester compound; manufactured by Daiichi Kogyo Seiyaku Co., Ltd .;
In the table, described as BzSc) 5 parts by mass Particulate additive solution 1 1 part by mass The above was put into a closed container and dissolved while stirring to prepare a dope solution. Next, using an endless belt casting apparatus, the dope solution was uniformly cast on a stainless steel belt support at a temperature of 33 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

On the stainless steel belt support, the solvent was evaporated until the amount of residual solvent in the cast (cast) film reached 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m.

The peeled cellulose ester film was stretched 20% in the width direction using a tenter while applying heat at 140 ° C. The residual solvent at the start of stretching was 15%.

Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m.

Thus, a cellulose ester film 101 having a dry film thickness of 40 μm was obtained.

<Preparation of cellulose ester films 102-121>
Cellulose ester films 102 to 121 were produced in the same manner as in the production of the cellulose ester film 101 except that the type of cellulose ester or the additive instead of the exemplified compound 14 was changed as shown in Table 1. In addition, the addition amount of the cellulose ester replaced with the used cellulose ester (TAC) was the same mass part as the cellulose ester (TAC).

Details of the materials used in Example 1 are shown below.

Cellulose ester B: cellulose acetate propionate having an acetyl substitution degree of 1.56, a propionyl substitution degree of 0.9, and a total acyl group substitution degree of 2.46 (denoted as CAP in the table)
Cellulose ester C: cellulose diacetate having an acetylation degree of 55.0% (described as DAC in the table)
Cellulose ester D: 30 parts by mass of cellulose acetate propionate having a degree of acetyl substitution of 0.2, a degree of substitution of propionyl of 2.55, and a degree of substitution of total acyl group of 2.75 and 70 parts by mass of dialnal BR85 (manufactured by Mitsubishi Rayon Co., Ltd.) Resin (described as CAP2 in the table) The structure of the comparative compound is as follows.

<< Evaluation of cellulose ester film >>
Each cellulose ester film sample produced as described above was evaluated as described below. The results are shown in Table 1.

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

Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), film retardation measurement was performed at a wavelength of 590 nm in a film that was allowed to stand for 24 hours in an environment of 23 ° C. and 55% RH. went. The above average refractive index and film thickness were input into the following formulas, and the values of in-plane retardation Ro and thickness direction retardation Rth were determined. The direction of the slow axis was also measured at the same time.

Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
However, nx represents the maximum refractive index in the film plane, ny represents the refractive index in the direction perpendicular to nx, nz represents the refractive index in the film thickness direction, and d represents the thickness (nm) of the film.

(Retardation fluctuation rate against humidity change)
The retardation value of the produced cellulose ester film was determined as described above, and the variation rate Rth (a) (%) was determined from the value. It is preferable that the fluctuation rate Rth (a) is small.

After humidity conditioning at 23 ° C. and 20% RH for 5 hours, the Rth value measured in the same environment was measured and this was designated as Rth (b), and the same film was continuously conditioned at 23 ° C. and 80% RH for 5 hours. After that, the Rth value measured in the same environment was obtained and this was set as Rth (c), and the variation rate Rth (a) was obtained from the following equation.

Rth (a) = | Rth (b) −Rth (c) | / Rth (b) × 100 (%)
Furthermore, the humidity-controlled sample was measured again in an environment of 23 ° C. and 55% RH, and it was confirmed that this change was a reversible change.

(Haze)
From the results of measurement using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.), evaluation was performed according to the following criteria.

A: Haze is less than 0.5% B: Haze is less than 0.5-1.0% Table C: Haze is less than 1.0-1.5% D: Haze is 1.5% or more where A, B was judged to be a practically acceptable level.

(Bleed-out resistance)
The 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 and evaluated according to the following criteria.

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: On the entire surface A clear bleed-out is recognized. A and B were judged to be practically satisfactory levels.

As is apparent from Table 1, the cellulose ester films 101 to 117 of the present invention using 1,3,5-triazine compounds substituted with an ethenyl group containing a ring structure are compared with the comparative cellulose ester films 118 to 120. It can be seen that the optical film is excellent in retardation development, has a small variation in the humidity of the retardation, has reduced haze, and has good bleeding out resistance. Further, it is understood that the cellulose ester films 101 to 105 and 108 to 112 using the exemplified compounds 12, 14, 16, 31, 34, and 36 included in the general formula (2) have a large improvement effect and are more preferable. . In addition, the cellulose-ester film 121 which does not contain a retardation developing agent has a small retardation value, and does not have a function as an optical compensation film at all.

Example 2
Cellulose was obtained in the same manner as in Example 1 except that the dope liquid used in the production of the cellulose ester film 101 of Example 1 was used and the flow rate of the dope liquid at the time of casting was changed to a film thickness as shown in Table 2. Ester films 201 to 206 were produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

As is apparent from Table 1, it can be seen that the cellulose ester films 201 to 206 of the present invention are excellent in retardation development, have a small variation in retardation humidity, have reduced haze, and have good bleedout resistance. . Furthermore, it can be seen that the effect is particularly high in the case where the film thickness is 202 to 205 in the range of 20 to 60 μm.

Example 3
<Preparation of polarizing plate>
A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times).

This was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. consisting of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

Next, according to the following steps 1 to 5, the front side of the polarizer and the cellulose ester films 101 to 120, 201 to 206 are bonded together, and Konica Minolta Tack KC4UY (cellulose ester film manufactured by Konica Minolta Opto Co., Ltd.) is attached to the back side. In addition, a polarizing plate was produced.

Step 1: The cellulose ester films 101 to 120 and 201 to 206 are immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to saponify the side to be bonded to the polarizer. A cellulose ester film was obtained.

Step 2: The polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.

Step 3: Excess adhesive adhered to the polarizer in Step 2 was gently wiped off and placed on the cellulose ester film treated in Step 1.

Step 4: The cellulose ester films 101 to 120 and 201 to 206 laminated in Step 3 and the Konica Minol Tack KC4UY are stacked on the polarizer side surface of the polarizer, the pressure is 20 to 30 N / cm ² , the conveyance speed is about 2 m / second. Pasted in minutes.

Step 5: A sample obtained by bonding the polarizer, the cellulose ester films 101 to 120, 201 to 206, and Konica Minolta Tack KC4UY, which are prepared in Step 4 in a dryer at 80 ° C., is dried for 2 minutes, and the polarizing plates 101 to 120 , 201 to 206 were produced.

<< Evaluation of polarizing plate >>
Next, the durability of the polarizing plate was evaluated as follows. The results are shown in Table 3.

(Light resistance)
The parallel transmittance (H0) and the direct transmittance (H90) of the undegraded sample were measured, and the degree of polarization was calculated according to the following equation. After that, each polarizing plate was subjected to forced deterioration treatment for 500 hours under the condition that there was no UV cut filter, and again, parallel transmittance (H0 ′) and direct transmittance (H90 ′) after forced deterioration treatment. Was measured, polarization degrees P0 and P500 were calculated according to the following formula, and the degree of polarization degree change was determined by the following formula.

<Calculation of degree of polarization P0, P500>
Polarization degree P0 = [(H0−H90) / (H0 + H90)] ^1/2 × 100
Polarization degree P500 = [(H0′−H90 ′) / (H0 ′ + H90 ′)] ^1/2 × 100
Polarization degree change = P0−P500
P0: Polarization degree before forced deterioration treatment P500: Polarization degree after 500 hours of forced deterioration treatment The degree of polarization change obtained as described above was determined according to the following criteria, and light resistance was evaluated.

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 , B was judged to be a practically acceptable level.

(Heat resistant)
Two 500 mm × 500 mm polarizing plate samples obtained as described above were heat-treated (conditions: left at 100 ° C. for 90 hours at 90 ° C.), and either the vertical or horizontal center line portion when placed in an orthogonal state. The length of the blank portion of the larger edge was measured, the ratio to the side length (500 mm) was calculated, and the determination was made as follows according to the ratio. Edge blanking can be determined visually by the fact that the edge portion of the polarizing plate that does not transmit light in an orthogonal state passes light. In the state of the polarizing plate, the display of the edge portion becomes invisible.

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 there is 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)
Here, it was determined that A and B were at a level having no practical problem.

As can be seen from Table 3, the polarizing plates 101 to 117 and 201 to 206 of the present invention are practically superior polarizing plates having better durability than the comparative polarizing plates 118 to 120.

Example 4
<Production of liquid crystal display device>
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated.

The polarizing plates on both sides of the 40-inch display KLV-40J3000 made by SONY were peeled off in advance, and the prepared polarizing plates 101 to 120 and 201 to 206 were bonded to both surfaces of the glass surface of the liquid crystal cell, respectively.

At that time, the direction of bonding of the polarizing plate is such that the surface of the cellulose ester film of the present invention is on the liquid crystal cell side, and the absorption axis of the polarizing plate previously bonded and the polarizing plates 101 to 120. The liquid crystal display devices 101 to 120 and 201 to 206 were fabricated in such a manner that the absorption axes of 201 to 206 were oriented in the same direction as the absorption axes of 201 to 206.

《Characteristic evaluation as liquid crystal display device》
The liquid crystal display device produced as described above was evaluated as described below. The results are shown in Table 4.

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

Front contrast = 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 Measure the front contrast of any 5 points on the liquid crystal display device, and use the following criteria evaluated.

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 is large Here, A and B were judged to be at a level where there is no practical problem.

(Viewing angle degradation)
The viewing angle of the liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. Subsequently, the viewing angle of the produced liquid crystal display device was measured in an environment of 23 ° C., 20% RH, and further 23 ° C., 80% RH, and evaluated according to the following criteria. Finally, viewing angle measurement was performed again in an environment of 23 ° C. and 55% RH, and it was confirmed that the change during the measurement was a reversible fluctuation. These measurements were made after the liquid crystal display device was placed in the environment for 5 hours.

A: No viewing angle variation is observed B: Viewing angle variation is slightly recognized C: Viewing angle variation is observed Here, A and B were determined to be at a level that is not problematic in practice.

As is apparent from Table 4, the liquid crystal display devices 101 to 117 and 201 to 206 using the polarizing plates 101 to 117 and 201 to 206 of the present invention are the liquid crystal display devices 118 to 118 using the comparative polarizing plates 118 to 120, respectively. It can be seen that the liquid crystal display device is extremely stable and excellent in durability with respect to 120, having no front contrast unevenness, and having no viewing angle fluctuation even under conditions of changing humidity.

Claims

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

(In the formula, R 11 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a heterocyclic group. R 12 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group. R 13 represents a hydrogen atom or a substituent, at least one group of R 11 , R 12 and R 13 represents a group containing a cycloalkyl group, an aryl group or a heterocyclic group, and R 14 and R 15 are substituted or An unsubstituted methyl group or a group represented by * —CR 23 ═CR 22 —L 2 —R 21 (* represents a bonding position with a 1,3,5-triazine ring) R 21 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, .R 22 representing an aryl group or a heterocyclic group represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group R 23 is .L 1 and L 2 represent a hydrogen atom or a substituent is a single bond, -CO -, - COO- or -CONR 17 - be represented .R 14 and R 15 are same, or different When R 14 or R 15 represents * -CR 23 = CR 22 -L 2 -R 21 , it may be the same as or different from * -CR 13 = CR 12 -L 1 -R 11 (* Represents the bonding position with the 1,3,5-triazine ring.) R 17 represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group.)
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 the formula, R 31 , R 32 and R 33 represent a cycloalkyl group, an aryl group or a heterocyclic group.)
The optical film according to claim 1, wherein the optical film is an optical film having a cellulose ester.
4. The optical film according to claim 1, wherein the optical film has a thickness of 20 to 60 μm.
The optical film according to any one of claims 1 to 4, wherein the retardation Ro represented by the following formula is 20 to 100 nm and Rth is 70 to 300 nm.
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(However, nx represents the refractive index in the direction x in which the refractive index is maximum in the in-plane direction of the optical film, and ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the optical film. , 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 comprising the optical film according to any one of claims 1 to 5 on at least one surface of a polarizer.
A liquid crystal display device comprising the polarizing plate according to claim 6 on at least one surface of a liquid crystal cell.
Retardation expression agent characterized by being represented by the following general formula (1).

(In the formula, R 11 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group or a heterocyclic group. R 12 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group. R 13 represents a hydrogen atom or a substituent, and at least one group of R 11 , R 12 and R 13 includes a cycloalkyl group, an aryl group or a heterocyclic group, and R 14 and R 15 are substituted or unsubstituted. A methyl group or a group represented by * —CR 23 ═CR 22 —L 2 —R 21 (* represents a bonding position with a 1,3,5-triazine ring), where R 21 represents a hydrogen atom; , alkyl group, cycloalkyl group, alkenyl group, an aryl group or a heterocyclic group .R 22 is a hydrogen atom, an alkyl group, .R a cycloalkyl group, an aryl group or a heterocyclic group 23 Represents a hydrogen atom or a substituent, L 1 and L 2 represent a single bond, —CO—, —COO—, or —CONR 17 —, and R 14 and R 15 may be the same or different. , R 14 or R 15 represents * -CR 23 = CR 22 -L 2 -R 21 , it may be the same as or different from * -CR 13 = CR 12 -L 1 -R 11 ( (* Represents a bonding position with the 1,3,5-triazine ring.) R 17 represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group.)