JP5724705B2 - Optical film, polarizing plate and liquid crystal display device using the same - Google Patents

Description

  The present invention relates to 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 optics. Among them, an optical film (cellulose ester film) containing cellulose ester is widely used because of its excellent bonding property to polyvinyl alcohol used for a polarizer.

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

  For example, oxadiazole compounds and thiadiazole compounds are disclosed as compounds added to cellulose (see, for example, Patent Document 1 and Patent Document 2). However, although the compound described in Patent Document 1 has an improved ability to increase the Ro value, which is in-plane retardation, the ability to increase the Rth value, which is a retardation in the thickness direction, is low, and improvement has been demanded. Further, the durability as a compound and the compatibility with cellulose were insufficient.

  The compound described in Patent Document 2 is insufficient in the required retardation increasing ability, and it is necessary to increase the amount of addition in order to impart the target retardation. Therefore, the problem that it is inferior to bleed-out tolerance and slitting characteristic generate | occur | produced.

  In addition, a method for producing an optical compensation film by aligning a liquid crystalline compound having an oxadiazole skeleton and a thiadiazole skeleton on a substrate is disclosed (for example, see Patent Document 3). However, these methods have a problem that the manufacturing process becomes complicated because it is necessary to align the liquid crystalline compound after coating and rubbing the alignment film on the substrate. In addition, even if these compounds are directly dissolved in cellulose ester, compatibility is not obtained, resulting in a cloudy film or a bleed-out film, which is difficult to use as an optical compensation film.

  On the other hand, the development of thin and light notebook PCs and thin and large-screen TVs has progressed, and along with this, the demand for thinner, larger and higher performance optical compensation films for liquid crystal display devices has become stronger. . The humidity durability of the cellulose ester film depends on the film thickness, and can be improved by reducing the film thickness. On the other hand, if the film thickness is reduced, the retardation value decreases. A compound having high expression is required, and for example, a method of adding an 1,3,5-triazine compound and obtaining an optical compensation film has been proposed (see, for example, Patent Document 4). However, even if this compound is used, the retardation is not sufficiently developed. Further, a polarizing plate produced using this optical compensation film and a liquid crystal display device using the polarizing plate have durability such as light resistance and heat and humidity resistance. Turned out to be inferior. Further, there were problems of uneven front contrast and deterioration of viewing angle under high heat and high humidity.

  As described above, the conventionally known retardation developing agent has various problems, and further improvement is desired.

JP 2007-23124 A JP 2000-275435 A JP 2007-246672 A JP 2006-188718A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical film having high retardation expression and good bleeding resistance, slitting characteristics, and heat and humidity resistance. Furthermore, it is to provide a polarizing plate and a liquid crystal display device that have good light resistance and heat and humidity resistance and are excellent in front contrast unevenness and viewing angle deterioration using the optical film.

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

  1. An optical film containing a cellulose ester, wherein the optical film contains a compound represented by the following general formula (1).

(In the formula, A, B and C represent a ring structure, and R _1, R ₂ and R ₃ represent a heterocyclic group, an alkyl group, a cycloalkyl group, an alkyloxy group, an aryloxy group, an aryloxycarbonyl group, an arylcarbonyl group. An oxy group, an acyl group, an acyloxy group, an amino group, an imide group, a carboxy group, a cyano group, an amide group, a carbamoyl group, an alkylthio group, and an arylthio group, n and m represent an integer of 0 to 5, and p represents 0. Represents an integer of ˜4, X represents an oxygen atom or a sulfur atom.)
2. 2. The optical film as described in 1 above, wherein the compound represented by the general formula (1) is represented by the following general formula (2).

(In the formula, R ₁₁ and R ₂₂ and R ₃₃ are a heterocyclic group, an alkyl group, a cycloalkyl group, an alkyloxy group, an aryloxy group, an aryloxycarbonyl group, an arylcarbonyloxy group, an acyl group, an acyloxy group, and an amino group. , An imide group, a carboxy group, a cyano group, an amide group, a carbamoyl group, an alkylthio group, and an arylthio group, n ₁ and m ₁ represent an integer of 0 to 5, and p ₁ represents an integer of 0 to 4. X ₁ represents an oxygen atom or a sulfur atom.)
3. 3. The optical film as described in 1 or 2 above, wherein X in the general formula (1) is an oxygen atom.

  4). 4. The optical film as described in any one of 1 to 3 above, wherein the LogP value of the compound represented by the general formula (1) is 2.0 to 9.0.

  5. 5. The optical film as described in any one of 1 to 4, wherein the cellulose ester satisfies the following formulas (a) and (b) simultaneously.

Formula (a) 1.5 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
(In the formula, X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the propionyl group or butyryl group, or a mixture thereof.)
6). 6. The optical film according to any one of 1 to 5, wherein the optical film has a thickness in the range of 20 to 60 μm.

  7). Retardation Ro value represented by a following formula is in the range of 20-150 nm, Rth value is in the range of 70-300 nm, The optical film of any one of said 1-6 characterized by the above-mentioned.

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 is a measured value at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, respectively, and d (nm) represents the thickness of the optical film. )
8). 8. A polarizing plate comprising the optical film according to any one of 1 to 7 on at least one surface of a polarizer.

  9. 9. A liquid crystal display device comprising the polarizing plate according to 8 on at least one surface of a liquid crystal cell.

  According to the present invention, it is possible to provide an optical film having high retardation development properties and excellent bleeding out resistance, slitting characteristics, light resistance, and heat and humidity resistance. Furthermore, the optical film can be used to provide a polarizing plate and a liquid crystal display device that have good light resistance and heat and humidity resistance and are excellent in front contrast unevenness and viewing angle deterioration.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments 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 containing a cellulose ester containing a retardation developer that can solve the above-mentioned problems, the present inventors include an oxadiazole compound or a thiadiazole compound according to the present invention in the optical film. Thus, it has been found that an optical film having high retardation development property and excellent bleeding out resistance, slitting characteristics, and heat and humidity resistance can be obtained. Moreover, when the obtained optical film was used, it discovered that the polarizing plate and liquid crystal display device which have favorable light resistance and heat-and-humidity resistance, and are excellent in front contrast nonuniformity and viewing angle deterioration are obtained. Although the detailed reason has not been elucidated, the interaction and compatibility with cellulose are increased by using an optical film containing the compound according to the present invention having a specific skeleton and a specific substituent. Since it becomes easy to orient with a cellulose chain, it has high retardation expression, and it is thought that bleed-out resistance and heat resistance improve.

  Specifically, when the oxadiazole compound or thiadiazole compound having a specific substituent is used as a retardation enhancer, the present inventors have found that the above problems can be solved and have reached the present invention.

<Compound represented by the general formula (1)>
First, the compound represented by the general formula (1) according to the present invention will be described.

  In the general formula (1), A, B and C each represent a ring structure. The ring structure includes a cycloalkyl group (eg, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, etc.), an aryl group (eg, phenyl group, naphthyl group, etc.), a heterocyclic group (eg, pyridyl group, pyrimidyl group, etc.) Oxazolyl group, thiazolyl group, oxadiazolyl group, thiadiazolyl group, imidazolyl group, etc.). From the viewpoint of retardation development, an aryl group and a heterocyclic group are preferable, and an aryl group is particularly preferable.

  As long as A, B, and C are the rings described above, they may be the same or different from each other.

R _1, R ₂ and R ₃ in the general formula (1) are each a heterocyclic group (for example, a pyridyl group, a pyrimidyl group, an oxazolyl group, a thiazolyl group, an oxadiazolyl group, a thiadiazolyl group, an imidazolyl group), an alkyl group (for example, , Methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (for example, cyclopropyl group, cyclopentyl group, Cyclohexyl group, adamantyl group, etc.), alkyloxy group (eg, methoxy group, ethoxy group, 2-ethylhexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), aryloxycarbonyl group (eg, phenyl) Oxycarbonyl group), arylcarbonyl Xyl group (for example, benzoyloxy group, etc.), acyl group (for example, acyl group, propionyl group, benzoyl group, etc.), acyloxy group (for example, acetyloxy group, etc.), amino group (for example, amino group, ethylamino group) Dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, phenylamino group, toluidino group, etc.), imide group, carboxy group, cyano group, amide group (for example, acetylamino group, Benzoylamino group etc.), carbamoyl group (eg aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group etc.), alkylthio group (eg methylthio group, Ethylchi Group), an arylthio group (e.g., phenylthio group, naphthylthio group, etc.).

When R _1, R _2, and R ₃ in the general formula (1) have the above-described substituent, both high retardation expression and compatibility can be achieved. The detailed mechanism is unknown, but when the interaction with the cellulose ester is strong, the retardation ability is reduced by inhibiting the orientation ability of the cellulose ester itself, and when the interaction with the cellulose ester is weak Since the additive is not aligned with the cellulose chain, retardation developability is lowered.

R _1, R ₂ and R ₃ in the general formula (1) are an alkyl group, a heterocyclic group, an alkyloxy group, an acyl group, an aryloxycarbonyl group, and a cycloalkyl group from the viewpoint of retardation development and compatibility. An amino group, a carbamoyl group, an amide group, and an imide group are preferable, and an alkyloxy group, an aryloxycarbonyl group, an acyl group, a heterocyclic group, an amino group, a carbamoyl group, and an amide group are more preferable.

R _1, R ₂ and R ₃ in the general formula (1) may have a substituent, and examples of the substituent include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, t-butyl). Group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (eg, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, etc.), aryl group (eg, phenyl group, Naphthyl group etc.), heterocyclic group (eg pyridyl group, pyrimidyl group, oxazolyl group, thiazolyl group, oxadiazolyl group, thiadiazolyl group, imidazolyl group etc.), acylamino group (eg acetylamino group, benzoylamino group etc.), alkylthio Group (eg, methylthio group, ethylthio group, etc.), arylthio group (eg , Phenylthio group, naphthylthio group, etc.), alkenyl group (for example, vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, styryl group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkynyl group (eg, propargyl group, etc.), alkylsulfonyl group (eg, methyl) Sulfonyl group, ethylsulfonyl group, etc.), arylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, etc.), alkylsulfinyl group (eg, methylsulfinyl group, etc.), arylsulfinyl group (eg, phenylsulfinyl group, etc.), phosphono Group, acyl group (for example, acetyl group, pivalloy) Group, benzoyl group, etc.), carbamoyl group (eg, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group) Group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylamino Sulfonyl group etc.), sulfonamide group (eg methanesulfonamide group, benzenesulfonamide group etc.), cyano group, alkyloxy group (eg meso Toxyl group, ethoxy group, propoxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), siloxy group, acyloxy group (for example, acetyloxy group, benzoyloxy group, etc.), sulfonic acid group, sulfonic acid Salts, aminocarbonyloxy groups, amino groups (eg, amino groups, ethylamino groups, dimethylamino groups, butylamino groups, cyclopentylamino groups, 2-ethylhexylamino groups, dodecylamino groups), anilino groups (eg, phenyl) Amino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc., imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido) Group, dodecylure 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.), carbamate group (eg methyl carbamate group, phenyl carbamate group), alkyloxyphenyl group (eg methoxyphenyl group etc.), acyloxyphenyl group (For example, an acetyloxyphenyl group), a thioureido group, a carboxyl group, a salt of a carboxylic acid, a hydroxyl group, a mercapto group, and a nitro group. A plurality of these substituents may be further substituted with the same group, and adjacent substituents may be bonded to form a ring.

R _1, R ₂ and R ₃ in the general formula (1) may be the same or different.

In the general formula (1), n and m represent an integer of 0 to 5, and when n or m represents an integer of 2 to 5, R ₁ or R ₂ may be the same or different.

In the general formula (1), p represents an integer of 0 to 4, and when p represents an integer of 2 to 4, R ₃ may be the same or different.

In the general formula (1), R _1, R ₂ and R ₃ can be bonded to A, B and C at an arbitrary position.

  In the general formula (1), X represents an oxygen atom or a sulfur atom, and an oxygen atom is preferable from the viewpoint of color tone and light resistance.

  In the general formula (1), a compound having three or more identical oxadiazole rings or thiadiazole rings in the molecule (for example, comparative compound C-005 described later) cannot be formed. When such a multimer is formed, solubility and compatibility are remarkably lowered.

R _11, R ₂₂ and R ₃₃ in the general formula (2) have the same meanings as R _1, R ₂ and R ₃ in the general formula (1), respectively, and preferred groups are also the same.

In the general formula (2), R _11, R ₂₂ and R ₃₃ can be bonded to the phenyl group at an arbitrary position.

N _1, m ₁ , and p ₁ in the general formula (2) have the same meanings as n, m, and p in the general formula (1), respectively.

  The LogP value of the compounds of the general formula (1) and the general formula (2) is preferably 2 to 9, and more preferably 3 to 8.

  Here, the LogP value will be described.

  The log P value is generally a parameter indicating whether a compound is distributed between water and oil (octanol), and a method of actually adding a compound to water and octanol and measuring the distribution rate, Various methods such as a method of obtaining by calculation have been proposed.

  The octanol-water partition coefficient (log P value) can be measured by a flask soaking method described in JIS Z-7260-107 (2000). Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement.

  As a calculation method, Crippen's fragmentation method ("J. Chem. Inf. Comput. Sci.", 27, p21 (1987)), Viswanadhan's fragmentation method ("J. Chem. Inf. Comput. Sci."). , 29, p163 (1989)), Broto's fragmentation method (“Eur. J. Med. Chem.-Chim. Theor.”, 19, p71 (1984)), CLogP method (references) Leo, A., Jow, PYC, Silipo, C., Hansch, C., J. Med. Chem., 18, 865 1975) and the like are preferably used.

  Regarding the log P value of each solvent in the present invention, the structural formula of the solvent is input to Chem Draw Ultra 12.0 manufactured by Cambridge Soft, and the calculated value displayed in “log P” in “Chemical Properties” is used. To do.

  By setting the LogP value of the compounds of the general formula (1) and the general formula (2) within the above range, the compatibility with the cellulose ester is improved.

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

<Synthesis example>
The compound represented by the general formula (1) according to the present invention can be synthesized by a general method. Synthesis examples of exemplary compounds are described below.

(Synthesis of Exemplary Compound A-003)
Suspend 5.0 g of 3,4,5-trimethoxybenzoic acid in 20 ml of toluene, add 9.0 g of thionyl chloride and 0.5 ml of DMF and heat at 120 ° C. for 2 hours. After the reaction, toluene and excess thionyl chloride are added. Distilling under reduced pressure gave 3,4,5-trimethoxybenzoic acid chloride.

  In another flask, 2.2 g of terephthalic acid dihydrazide was dissolved in 25 ml of N-methylpyrrolidone and heated to 80 ° C. To this solution, a 3,4,5-trimethoxybenzoic acid chloride solution dissolved in 10 ml of N-methylpyrrolidone was added dropwise, followed by heating and stirring at 80 ° C. for 4 hours. Thereafter, the reaction solution was cooled, and 20 ml of water and 30 ml of methanol were added and stirred. The precipitated solid was filtered and dried.

  4.0 g of the obtained solid and 15 ml of phosphorus oxychloride were added to the flask, and the mixture was heated and stirred at 100 ° C. for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and the reaction solution was poured into 1 L of water at 5 ° C. and stirred. The precipitated solid was filtered, washed with water, and the crystals were washed with methanol. The obtained solid was suspended in 100 ml of methanol and heated to reflux for 2 hours. The solid was filtered, washed with methanol and dried to obtain 2.7 g of Exemplified Compound A-003. The obtained exemplary compound A-003 has a molecular structure identified by NMR and mass spectrum.

(Synthesis of Exemplary Compound A-004)
3.3 g of parahydroxybenzoic acid was dissolved in 30 ml of acetone and 2 ml of pyridine and stirred in a water bath. To this solution, 2.0 g of acetyl chloride was added dropwise and stirred as it was for 3 hours. The reaction solution was concentrated under reduced pressure and dissolved by adding 50 ml of ethyl acetate. This solution was separated with 20 ml of 1N hydrochloric acid solution, and then separated with pure water until neutral. The ethyl acetate layer was concentrated under reduced pressure and 20 ml of toluene was added. To this solution, 9.0 g of thionyl chloride and 0.5 ml of DMF were added and heated at 120 ° C. for 2 hours. After completion of the reaction, toluene and excess thionyl chloride were distilled off under reduced pressure to obtain acid chloride 1.

  In another flask, 2.2 g of terephthalic acid dihydrazide was dissolved in 25 ml of N-methylpyrrolidone and heated to 80 ° C. To this solution, the acid chloride 1 dissolved in 10 ml of N methylpyrrolidone was added dropwise, and then heated and stirred at 80 ° C. for 4 hours. Thereafter, the reaction solution was cooled, and 20 ml of water and 30 ml of methanol were added and stirred. The precipitated solid was filtered and dried.

  4.0 g of the obtained solid and 15 ml of phosphorus oxychloride were added to the flask, and the mixture was heated and stirred at 100 ° C. for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and the reaction solution was poured into 1 L of water at 5 ° C. and stirred. The precipitated solid was filtered, washed with water, and the crystals were washed with methanol. The obtained solid was suspended in 100 ml of methanol and heated to reflux for 2 hours. The solid was filtered, washed with methanol and dried to obtain 2.5 g of Exemplified Compound A-003. The obtained exemplary compound A-004 was molecularly identified by NMR and mass spectrum.

(Synthesis of Exemplary Compound A-028)
10 g of gallic acid hydrate, 40 ml of acetic anhydride and 0.1 g of sulfuric acid were added to the flask and stirred at 80 ° C. for 15 minutes. After completion of the reaction, the reaction solution was cooled to about 5 ° C., and 300 ml of water was added to precipitate a solid. The mixture was stirred for 2 hours, filtered, washed with water and dried to obtain 7.2 g of Intermediate A.

  Intermediate A 7.0 g, toluene 40 ml, thionyl chloride 9.0 g and DMF 0.5 ml were added to a flask and heated at 120 ° C. for 2 hours. After completion of the reaction, toluene and excess thionyl chloride were distilled off under reduced pressure to remove acid chloride. Body 2 was obtained.

  In another flask, 2.2 g of isophthalic acid dihydrazide was dissolved in 25 ml of N-methylpyrrolidone and heated to 80 ° C. The acid chloride 2 dissolved in 10 ml of N methylpyrrolidone was added dropwise to this solution, and then heated and stirred at 80 ° C. for 4 hours. Thereafter, the reaction solution was cooled, and 20 ml of water and 30 ml of methanol were added and stirred. The precipitated solid was filtered and dried. 4.0 g of the obtained solid and 15 ml of phosphorus oxychloride were added to the flask, and the mixture was heated and stirred at 100 ° C. for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and the reaction solution was poured into 1 L of water at 5 ° C. and stirred. The precipitated solid was filtered, washed with water, and the crystals were washed with methanol. The obtained solid was suspended in 100 ml of methanol and heated to reflux for 2 hours. The solid was filtered, washed with methanol and dried to obtain 4.3 g of Exemplified Compound A-028. The obtained exemplary compound A-028 was identified for molecular structure by NMR and mass spectrum.

(Synthesis of Exemplary Compound A-035)
10.0 g of parahydroxybenzoic acid was dissolved in 60 ml of acetone and 8 ml of pyridine and stirred in a water bath. To this solution, 6.0 g of acetyl chloride was added dropwise and stirred as it was for 3 hours. The reaction solution was concentrated under reduced pressure and dissolved by adding 50 ml of ethyl acetate. This solution was separated with 20 ml of 1N hydrochloric acid solution, and then separated with pure water until neutral. The ethyl acetate layer was concentrated under reduced pressure and 20 ml of toluene was added. To this solution, 9.0 g of thionyl chloride and 0.5 ml of DMF were added and heated at 120 ° C. for 2 hours. After completion of the reaction, toluene and excess thionyl chloride were distilled off under reduced pressure to obtain acid chloride 3.

  9.5 g of tert-butyl carbamate was dissolved in a mixed solvent of 200 ml of diethyl ether and 12 ml of pyridine. To this solution, acid chloride 2 dissolved in 50 ml of diethyl ether was added dropwise and stirred at 10 ° C. for 1 hour. Thereafter, the mixture was stirred at about 5 ° C. for 1 hour, then warmed to room temperature, and further stirred for 1 hour. 250 ml of water was added to the reaction solution, and the aqueous layer was removed after stirring.

  Subsequently, the solution was separated with 100 ml of 5% hydrochloric acid, then with a 5% aqueous sodium hydrogen carbonate solution, and then with pure water until neutrality. The residue after the ether layer was concentrated under reduced pressure was cooled to 10 ° C., and 50 ml of trifluoroacetic acid was added and stirred. Thereafter, the mixture was warmed to room temperature and stirred for 1 hour. Trifluoroacetic acid was distilled off under reduced pressure, and 10% aqueous sodium carbonate solution was added to the residue and stirred. The precipitated solid was filtered, washed with water and dried to obtain 11.5 g of Intermediate B.

  5-aminoisophthalic acid hydrate (5.0 g) was dissolved in a mixed solvent of acetone (40 ml) and pyridine (2.5 g), and the mixture was stirred in a water bath. To this solution, 3.8 g of benzoyl chloride was added dropwise and stirred as it was for 3 hours. The reaction solution was concentrated under reduced pressure and dissolved by adding 50 ml of ethyl acetate. This solution was separated with 20 ml of 1N hydrochloric acid solution, and then separated with pure water until neutral. The ethyl acetate layer was concentrated under reduced pressure and 50 ml of toluene was added. To this solution, 12.0 g of thionyl chloride and 0.5 ml of DMF were added and heated at 120 ° C. for 2 hours. After completion of the reaction, toluene and excess thionyl chloride were distilled off under reduced pressure to obtain acid chloride 4.

  10.0 g of intermediate B was dissolved in 100 ml of N methylpyrrolidone and heated to 80 ° C. The acid chloride 4 dissolved in 10 ml of N methylpyrrolidone was added dropwise to this solution, and then heated and stirred at 80 ° C. for 4 hours. Thereafter, the reaction solution was cooled, and 50 ml of water and 100 ml of methanol were added and stirred. The precipitated solid was filtered and dried.

  The obtained solid (15.3 g) and phosphorus oxychloride (100 ml) were added to a flask, and the mixture was heated and stirred at 100 ° C. for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and the reaction solution was poured into 3 L of 5 ° C. water and stirred. The precipitated solid was filtered, washed with water, and the crystals were washed with methanol. The obtained solid was suspended in 300 ml of methanol and heated to reflux for 2 hours. The solid was filtered, washed with methanol and dried to obtain 4.3 g of Exemplified Compound A-035. The obtained exemplary compound A-035 was identified for molecular structure by NMR and mass spectrum.

(Synthesis of Exemplary Compound B-003)
Suspend 5.0 g of 3,4,5-trimethoxybenzoic acid in 20 ml of toluene, add 9.0 g of thionyl chloride and 0.5 ml of DMF and heat at 120 ° C. for 2 hours. After the reaction, toluene and excess thionyl chloride are added. Distilling under reduced pressure gave 3,4,5-trimethoxybenzoic acid chloride. In another flask, 2.2 g of terephthalic acid dihydrazide was dissolved in 25 ml of N-methylpyrrolidone and heated to 80 ° C. To this solution, a 3,4,5-trimethoxybenzoic acid chloride solution dissolved in 10 ml of N-methylpyrrolidone was added dropwise, followed by heating and stirring at 80 ° C. for 4 hours. Thereafter, the reaction solution was cooled, and 20 ml of water and 30 ml of methanol were added and stirred. The precipitated solid was filtered and dried.

  4.0 g of the obtained solid and 5.5 g of Lawesson's reagent were dissolved in 200 ml of tetrahydrofuran and heated in a microwave for 20 minutes (300 W, 90 ° C.). After cooling to room temperature, the solvent was distilled off under reduced pressure. Ethyl acetate and water were added to the residue, and the mixture was stirred and filtered. The filtered solid was purified by silica gel column chromatography to obtain 2.73 g of Exemplified Compound B-003. The obtained exemplary compound B-003 has a molecular structure identified by NMR and mass spectrum.

  Other compounds can be synthesized in the same manner.

  In order for the compound represented by the general formula (1) according to the present invention to give a desired retardation to the optical film, the compound represented by the general formula (1) is applied to a film containing a cellulose ester. Instead, it must be added to the film containing the cellulose ester.

  The compound represented by the general formula (1) according to the present invention can be contained by appropriately adjusting the amount for imparting a desired retardation. The content is preferably 1 to 15% by mass, more preferably 1 to 10% by mass, and particularly preferably 2 to 5% by mass. Within this range, sufficient retardation can be imparted to the cellulose ester according to the present invention, and compatibility and bleed-out resistance can be kept good.

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

(Wavelength dispersion control agent)
The optical film of the present invention can also contain a wavelength dispersion controlling agent. Here, the “wavelength dispersion controlling agent” is a compound that adjusts the wavelength dispersion of the retardation of the film.

  As the wavelength dispersion controlling agent in the present invention, a discotic compound described in JP-A Nos. 2001-166144 and 2003-3446556 and a compound described in JP-A 2010-163482 can be preferably used. .

  The wavelength dispersion controlling agent in the invention preferably has an absorption maximum in a wavelength range of 250 nm to 400 nm. More preferably, it has an absorption maximum in a wavelength range of 270 nm to 380 nm.

  The wavelength dispersion controlling agent used in the present invention may be added in advance when preparing a mixed solution of cellulose acylate, but it is added at any time until the dope of cellulose acylate is prepared in advance and cast. May be. In the latter case, in order to perform in-line addition and mixing of a dope solution in which cellulose acylate is dissolved in a solvent and a solution in which a wavelength dispersion controlling agent and a small amount of cellulose acylate are dissolved, for example, a static mixer ( In-line mixers such as Toray Engineering Co., Ltd., SWJ (Toray Static In-Pipe Mixer Hi-Mixer) are preferably used.

  The post-added wavelength dispersion controlling agent may be mixed with a matting agent at the same time, or may be mixed with additives such as a retardation controlling agent, a plasticizer, a deterioration preventing agent and a peeling accelerator. When using an in-line mixer, it is preferable to concentrate and dissolve under high pressure, and the type of the pressurized container is not particularly limited, as long as it can withstand a predetermined pressure and can be heated and stirred under pressure. In addition to the pressure vessel, other instruments such as a pressure gauge and a thermometer are appropriately disposed. The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating.

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

  Moreover, the wavelength dispersion control agent used for this invention can be used individually or in mixture of 2 or more types. 1.0-20 mass% is preferable with respect to 100 mass parts of cellulose acylates, and, as for the addition amount of the wavelength dispersion controlling agent used for this invention, 1.5-15 mass% is more preferable, 2.0-10 mass % Is most preferred.

  The addition method of the wavelength dispersion control agent used in the present invention may be added to the cellulose acylate solution (dope) after dissolving the wavelength dispersion control agent in an organic solvent such as alcohol, methylene chloride or dioxolane, or You may add directly in dope composition.

<Optical film>
Next, the details of the optical film of the present invention will be described.

  In this invention, an optical film is a functional film used for various display apparatuses, such as a liquid crystal display, a plasma display, and an organic electroluminescent display. Specifically, it is a polarizing plate protective film for liquid crystal display apparatuses, retardation film, antireflection Films, brightness enhancement films, hard coat films, antiglare films, antistatic films, optical compensation films such as viewing angle expansion, and the like are included.

  As the resin of the film that becomes the base material of the optical film of the present invention, a cellulose ester resin (also referred to simply as a cellulose ester in the present invention) is used, but other resins that can be used in combination include polycarbonate resins and polystyrene. Resin, polysulfone resin, polyester resin, polyarylate resin, acrylic resin, olefin resin (norbornene resin, cyclic olefin resin, cyclic conjugated diene resin, vinyl alicyclic hydrocarbon resin, etc.), etc. Can be mentioned. In this, you may use together with at least 1 resin of polycarbonate-type resin, acrylic resin, and cyclic olefin-type resin. When using resin other than cellulose ester, the content is preferably 5 to 70% by mass.

  The optical film of the present invention is preferably used for a polarizing plate protective film, a retardation film, and an optical compensation film. It is preferable that the retardation film also serves as a polarizing plate protective film.

<Cellulose ester>
Although it does not specifically limit as a cellulose ester based on this invention, It is preferable that it is a C2-C22 linear or branched carboxylic acid ester, These carboxylic acid may form a ring and aromatic carboxylic acid. It may be an acid ester. 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 a preferred cellulose ester, specifically, in addition to cellulose acetate, a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate. The mixed fatty acid ester of cellulose is mentioned.

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

Formula (a) 2.0 ≦ X + Y ≦ 2.5
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 acetate propionate (Y; propionyl group, Y> 0) are most preferably used. The cellulose acetate propionate satisfies 1.0 ≦ X ≦ 2.4, preferably 0.1 ≦ Y ≦ 1.5, and 2.0 ≦ X + Y ≦ 2.5. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  Further, in order to obtain optical characteristics 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 according to the present invention is preferably in the range of 60,000 to 300,000, since the mechanical strength of the resulting film is strong. Furthermore, the thing of 70000-200000 is used preferably.

  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 Corporation) Mw = 100000 to 500 calibration curves with 13 samples are used. Thirteen samples are used at approximately equal intervals.

  Although there is no limitation in particular as a cellulose of the raw material of the cellulose ester which concerns on this invention, Cotton linter, wood pulp, kenaf etc. can be mentioned. 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 known methods. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

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

<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 ester compound used in the present invention include the following, but are not limited thereto.

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

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  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 group in the pyranose structure or furanose structure is not particularly limited, and is a known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic A 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, cerotic 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-pyroca Succinic 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.

  An oligosaccharide ester compound can be applied as a compound having 1 to 12 at least one of a pyranose structure or a furanose structure.

  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, isomaltoligosaccharides, fructooligosaccharides, galactooligosaccharides, xylooligos. Sugar.

  Examples of sugar ester compounds 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 with respect to the cellulose ester. 5 to 20% by mass is preferable.

<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 comprising an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

  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 or phenolic hydroxy 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, xylitol and the like. 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.

  Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or 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 preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, 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 for 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 divalent or higher, preferably divalent to 20 valent polyvalent carboxylic acid and alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 to 20 valent.

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

Formula (b) Rb (COOH) m (OH) n
(However, Rb is an (m + n) -valent organic group, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group represents a carboxyl group, and an OH group represents an alcoholic or phenolic hydroxyl group.)
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.

  There is no restriction | limiting in particular as alcohol used for a polyhydric carboxylic acid ester compound, Well-known alcohol 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. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. 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 fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  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 alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. And aromatic monocarboxylic acids possessed by them, or derivatives thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

  The molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose ester.

  The alcohol used for the polyvalent carboxylic acid ester 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.

General formula (c) B- (GA) n-GB
(In the formula, B is a benzene monocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (c), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the polyester plasticizer used in the present invention include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, and normalpropyl. There exist benzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc., and these can be used as 1 type, or 2 or more types of mixtures, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester 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 (neo Pentyl 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 1,3-penta Diol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. It is used as one kind or a mixture of two or more kinds. In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  In addition, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds. 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 polyester plasticizer used in the present invention has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxyl value (hydroxy value) is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value (hydroxy value) is 15 mgKOH / g or less. Is.

  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 refluxing the monohydric alcohol, 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 under reduced pressure at 200 to 230 ° C. under a reduced pressure of 1.33 × 10 ⁴ Pa to 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. 4 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 of 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. Polymer X having a weight average molecular weight of 3000 to 30000 obtained by polymerization, and 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.

  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)
_{- [CH 2 -C (-Rc)} (- CO 2 Rd)] m- [CH 2 -C (-Re) (- CO 2 Rf-OH) -] n- [Xc] p-
General formula (Y)
_{Ry- [CH 2 -C (-Rg)} (- CO 2 Rh-OH) -] k- [Yb] q-
(In the formula, 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, and Yb can be copolymerized to Ya Represents a monomer unit, and m, n, k, p and q represent molar composition ratios, where m ≠ 0, n ≠ 0, k ≠ 0, m + n + p = 100, and k + q = 100.
The amount of these plasticizers added is preferably 0.5 to 30% by mass, and particularly preferably 5 to 20% by mass with respect to the cellulose ester.

<Ultraviolet absorber>
The optical film of the present invention can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, and further 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 salts, inorganic Examples thereof include powders.

  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, and these are all commercially available products from BASF 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 of the present invention preferably contains two or more ultraviolet absorbers.

  As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV 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 an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added 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, it is 0.5 with respect to the polarizing plate protective film. -10 mass% is preferable, and 0.6-4 mass% is still more preferable.

<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.

  Antioxidants have the 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, so it is contained in the optical film. It is preferable to do so.

  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-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-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-t-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 addition amount of these compounds is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose derivative.

<Fine particles>
The optical film of the present invention preferably contains fine particles in order to improve slipperiness.

  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 diameter of the fine particles is preferably 5 to 400 nm, and 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 optical film is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass. In the case of an optical 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 (above Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles are commercially available, for example, under the trade names 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 optical film low. In the optical film of 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 a dope that is a cellulose ester-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 cellulose ester in order to improve mixing with the dope. The amount of the cellulose ester 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 of this invention is demonstrated.

  The optical film of the present invention can be preferably used 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 of the present invention comprises a step of dissolving a cellulose ester and an additive in a solvent to prepare a dope, a step of casting the dope onto an endless metal support that moves indefinitely, a web of the cast dope Can be performed by a step of drying, a step of peeling from a metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding the finished film.

  The process for preparing the dope will be described. The concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy is poor. Become. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 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 cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester. 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 dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent. Therefore, depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, cellulose acetate (acetyl group substitution degree 2.4), cellulose acetate Propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope. 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 dissolution method of the cellulose ester 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 that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos. Moreover, after mixing a cellulose ester with a poor solvent and making it wet or swell, the method of adding a good solvent and melt | dissolving is also used preferably.

  The 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 cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more 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 cellulose ester can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose ester solution is filtered using a suitable 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 still more 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 cellulose ester 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, More preferably, it is 50 pieces / cm < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The 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 still more preferably 45 to 55 ° C.

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

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface. As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used. The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate. A preferable support body temperature is 0-40 degreeC, and 5-30 degreeC is still more preferable. 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 residual solvent amount 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. Yes, 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.

  Further, in the optical film drying step, 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, particularly Preferably it is 0-0.01 mass% or less.

  In the film drying step, 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 of 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.

  The drying temperature in the web drying step is preferably increased stepwise from 40 to 200 ° C.

  Although the film thickness of an optical film is not specifically limited, It is used within the range of 10-200 micrometers. In particular, the film thickness is particularly preferably 10 to 100 μm. More preferably, it exists in the range of 20-60 micrometers. If it is this range, since the improvement of the moisture permeability depending on the film thickness of a film and the expression of the retardation by the retardation developing agent concerning this invention can be compatible, it is preferable. Further, it is preferable that the film thickness is in this range since the slitting characteristics of the film are also improved.

  An optical film having a width of 1 to 4 m is used. In particular, 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 of 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 contracting the other while relaxing the tension.

  It is preferable that the draw ratios in the biaxial directions perpendicular to each other are finally 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. 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 between the rolls. 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 perform the width maintenance or the transverse stretching in the film forming process 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 of the present invention is used in the VA mode, a mode in which a total of two sheets are used on each side of the cell (two-sheet type) and a mode in which only one of the upper and lower sides of the cell is used (one sheet) Type).

  In the optical film of the present invention, the retardation Ro value represented by the above formula is preferably in the range of 20 to 150 nm at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, and further 70 nm to 145 nm. preferable. The Rth value is preferably in the range of 70 to 300 nm and more preferably 170 nm to 270 nm at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH. These retardation values can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).

  The slow axis or the fast axis of the optical film of the present invention is present in the film plane, and θ1 is preferably −1 ° or more and + 1 ° or less, assuming that the angle formed with the film forming direction is θ1. More preferably, it is 5 ° or more and + 0.5 ° or less. This θ1 can be defined as an orientation angle, and θ1 can be measured 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 of 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 heat and humidity resistance of the optical film in the present invention can be evaluated by dimensional change with respect to humidity change.

  The following method is used as a method for evaluating a dimensional change with respect to a thermal humidity change.

In the casting direction of the produced optical film, two marks (crosses) were attached and treated at 60 ° C. and 90% RH for 1000 hours, and the distance between the mark (cross) before and after treatment was measured with an optical microscope. Obtain the dimensional change rate (%). The dimensional change rate (%) is expressed by the following formula.
Dimensional change rate (%) = [(a1-a2) / a1] × 100
a1: Distance before thermo-humidity a2: Distance after thermo-humidity When an optical film is used as a protective film for a polarizing plate of a liquid crystal display device, unevenness or a change in retardation value occurs in the optical film due to dimensional changes due to moisture absorption. This causes problems such as a decrease in contrast and uneven color. In particular, the above problem becomes significant when the polarizing plate protective film is used in a liquid crystal display device used outdoors. However, if the dimensional change rate (%) under the above conditions is less than 0.5%, it can be evaluated that the optical film exhibits sufficiently low hygroscopicity. Furthermore, it is preferable that it is less than 0.3%.

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

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

  The haze of the optical film of 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 of the present invention, or by further stretching it.

<Polarizing plate>
The optical film of this invention can be used for the polarizing plate of this invention, and the liquid crystal display device of this invention using the same. The optical film of the present invention is preferably a film that also functions as a polarizing plate protective film. In this case, it is not necessary to prepare an optical film having a phase difference separately from the polarizing plate protective film. Thus, the manufacturing process can be simplified.

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

  The polarizing plate of the present invention can be produced by a general method. The optical film of 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 of the present invention is a liquid crystal display device, the optical film 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 Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8HY-X, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are preferably used.

  In addition to the antiglare layer or the clear hard coat layer, 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.

  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.

  For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to 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 for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB.

  In particular, it is preferably used for a VA (MVA, PVA) type liquid crystal display device.

  In particular, even in a large-screen liquid crystal display device with a 30-inch screen or more, it is possible to obtain a liquid crystal display device with excellent visibility such as front contrast by reducing coloring during black display due to light leakage.

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

Example 1
<Preparation of optical film 101>
<Fine particle dispersion 1>
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass Ethanol 85 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>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient 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 102 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 was completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of main dope solution>
Methylene chloride 343 parts by mass Ethanol 61 parts by mass Cellulose ester A: Cellulose diacetate having a substitution degree of 2.40 and a number average molecular weight of 70,000 (described as DAC in the table) 100 parts by mass Retardation developer: Exemplified compound A-001 4 parts by mass Monopet SB (Daiichi Kogyo Seiyaku Co., Ltd.) 5.7 parts by mass Particulate additive solution 1 1 part by mass The above was put into a sealed container and dissolved while stirring to prepare a dope solution. Next, an endless belt casting apparatus was used to uniformly cast the dope solution on a stainless steel belt support at a temperature of 35 ° 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 residual solvent amount in the cast (cast) film became 75%, and then peeled off from the stainless steel belt support with a peeling tension of 125 N / m.

  The peeled optical 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 17%.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 120 ° C. and the transport tension was 100 N / m.

  As described above, an optical film 101 having a dry film thickness of 40 μm was obtained.

<Preparation of optical films 102-150>
In the production of the optical film 101, the present invention is the same except that only the type of cellulose ester and the type and amount (parts by mass) of Example Compound A-001 as a retardation developer are changed as shown in Tables 1 and 2. Optical films 102 to 136 and comparative optical films 137 to 150 were produced. In addition, the addition amount of the cellulose ester replaced with the used cellulose ester A (DAC) was the same mass part as the cellulose ester A (DAC).

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

Cellulose ester B: Cellulose acetate propionate having a number average molecular weight of 70,000 having an acetyl group substitution degree of 1.58, a propionyl group substitution degree of 0.9, and a total acyl group substitution degree of 2.48 (denoted as CAP in the table)
Cellulose ester C: Cellulose triacetate having a number average molecular weight of 70,000 having an acetyl group substitution degree of 2.85 (described as TAC in the table)
Moreover, the structures of comparative compounds C-001 to C-007 are as follows.

<< Evaluation of optical film >>
Each optical film sample produced as described above was evaluated as described below.

(Compatibility evaluation)
The haze before stretching after drying the film before stretching for producing the optical films 101 to 150 at 120 ° C. for 15 minutes was measured using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.). From the results, evaluation was performed according to the following criteria.

A: Haze is less than 0.5% B: Haze is less than 0.5-1.0% C: Haze is less than 1.0-1.5% D: Haze is 1.5% or more E: Compound is precipitated here Therefore, it was judged that A and B were practically satisfactory levels.

(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-mentioned average refractive index and film thickness were input to 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
(Where nx is the maximum refractive index in the film plane, ny is the refractive index in the direction perpendicular to nx, nz is the refractive index in the film thickness direction, and d is the thickness (nm) of the film.)
(Slitting aptitude)
After attaching the 60 ° worn upper blade and the 90 ° lower blade to the hydraulic table press machine at a distance of 30 μm, each optical film was placed between both blades, and the lowering speed of the upper blade was 6 m / In minutes, 100 samples having a width of 90 cm and a length of 100 cm were continuously cut out. The cut surfaces of the cut samples were observed at 50 times using an optical microscope, and the sharpness was compared. The number of films with some defects such as burrs, cleavage, inability to cut, chip generation, etc. was counted, the defect rate was calculated, and slitting suitability was evaluated according to the following criteria.

A: The defect rate is less than 2% B: The defect rate is less than 2-5% C: The defect rate is less than 5-10% D: The defect rate is 10% or more Here, it is determined that A and B are practically acceptable levels. did.

(Bleed-out resistance)
The optical film is allowed to stand for 1000 hours in a high-temperature and high-humidity atmosphere at 80 ° C. and 90% RH, and then visually observed for the presence or absence of bleed-out (crystal precipitation) on the optical film surface, and the bleed-out resistance is evaluated according to the following criteria. It was.

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.

(Haze after stretching)
From the result of measuring the optical films 101 to 150 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 E: Compound is precipitated Here, it was determined that A and B were at a level having no practical problem.

(Heat resistance: dimensional change against heat humidity change)
In the casting direction of the produced optical film, two marks (crosses) were attached and treated at 60 ° C. and 90% RH for 1000 hours, and the distance between the mark (cross) before and after treatment was measured with an optical microscope. The heat and humidity resistance was evaluated by evaluating the dimensional change according to the following criteria.
Dimensional change rate (%) = [(a1-a2) / a1] × 100
In the formula, a1 represents a distance before heat treatment, and a2 represents a distance after heat treatment.
A: Less than 0.3% B: 0.3% or more, less than 0.5% C: 0.5% or more, less than 0.7% D: 0.7% or more The above results are shown in Tables 1 and 2. Show.

  As is clear from Tables 1 and 2, the optical films 101 to 136 of the present invention are more excellent in retardation than the comparative optical films 137 to 150, and have compatibility (haze) and brittleness (slitting). Applicability), durability (bleed out resistance), and heat and humidity resistance are found to be practically excellent optical films. In order to achieve the object of the present invention from the results of optical films 137 to 143 using comparative compounds C-001, C-002, C-003, C-004, C-005, C006, C007, a retardation developer It is said that a specific group is necessary for the substituent of the above, and compatibility and retardation expression are improved. In particular, C007, which is a comparative compound, has a retardation lower than that of the optical film 148 that is an additive-free optical film, and it can be seen that a specific substituent is required for high retardation. Further, from the results of optical films 135, 136, 144, and 145, the retardation developer in the present invention can be used as a good optical film because it is compatible with cellulose ester even if the amount added is increased in order to produce a large phase difference. I understand.

  In addition, the optical films 148 to 150 that do not contain a retardation developer have a remarkably large dimensional change and are not suitable as an optical compensation film.

Example 2
Optical film in the same manner as in Example 1 except that the dope liquid used in the production of the optical film 103 of Example 1 was used, and the flow rate of the dope liquid during casting was changed so that the film thickness was as shown in Table 3. 201-206 were produced and evaluated in the same manner as in Example 1.

  As is clear from Table 3, it can be seen that the optical films 201 to 206 of the present invention are excellent in retardation development, and are excellent in brittleness (slitting suitability) and durability (bleedout resistance). Further, it can be seen that the effect is particularly high in 202 to 205 having a film thickness 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 composed of 0.071 g of iodine, 5 g of potassium iodide, and 100 g of water for 55 seconds, and then immersed in an aqueous solution at 65 ° C. composed of 6 g of potassium iodide, 7.2 g of boric acid, and 100 g of water. This was washed with water and dried to obtain a polarizer.

  Subsequently, a polarizer, the optical films 101 to 150 and 201 to 206, and Konica Minolta Tack KC4UY (a cellulose ester film manufactured by Konica Minolta Opto Co., Ltd.) are bonded to the back surface in accordance with the following steps 1 to 5 to form a polarizing plate 101. -150 and polarizing plates 201-206 were produced.

  Step 1: It was immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to obtain an optical film having a saponified side to be bonded to a polarizer.

  Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.

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

Step 4: The optical films 101 to 150 and 201 to 206 laminated in Step 3 and the polarizer were bonded to the back side cellulose ester film at a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.

  Step 5: A sample prepared by bonding the polarizer prepared in Step 4 with the optical films 101 to 150, 201 to 206, and Konica Minoltack KC4UY in a dryer at 80 ° C. for 2 minutes, and polarizing plates 101 to 150, 201-206 were produced.

<< Evaluation of polarizing plate >>
Next, the durability of the polarizing plate was evaluated as follows.

(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 of no sunshine weather meter and no UV cut filter, and then again the parallel transmittance (H0 ′) and direct transmittance (H90 ′) after the 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 problematic 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.

  The above results are shown in Tables 4 and 5.

  As is clear from Tables 4 and 5, the polarizing plates 101 to 136 and 201 to 206 of the present invention are practically excellent polarizing plates that have better light resistance and heat and humidity resistance than the comparative polarizing plates 137 to 150. I understand that there is. In order to achieve the object of the present invention from the results of polarizing plates 137 to 143 using comparative compounds C-001, C-002, C-003C-004, C-005, C-006, and C-007, It turns out that the specific structure and substituent of a retardation expression agent are required. In addition, from the results of the polarizing plates 135, 136, 144, and 145, the retardation developer in the present invention is compatible with the cellulose ester even if the addition amount is increased in order to produce a large phase difference. It can be seen that the plate is a practically excellent polarizing plate.

  In Comparative Compounds C-002 and C-004, slight bubbles were generated in the film after the light resistance test and the heat and humidity resistance test. Although it is not understood in detail, it can be inferred that the bubbles are generated by decarboxylation of the carbamate groups substituted by C-002 and C-004.

  Polarizing plates 148 to 150 using an optical film that does not contain a retardation developer are poor in light resistance and heat and humidity resistance, and do not function as an optical film that protects the polarizing plate and as a polarizing plate.

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 in advance were peeled off, and the prepared polarizing plates 101 to 150 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 optical film of the present invention is on the liquid crystal cell side and the absorption axis is directed in the same direction as the polarizing plate previously bonded. Then, liquid crystal display devices 101 to 150 and 201 to 206 were produced.

《Characteristic evaluation as a liquid crystal display device》
The liquid crystal display device produced as described above was evaluated as described below.

(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 to measure the luminance from the normal direction of the display screen of white display and black display 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: Front contrast is 0 to less than 5% variation and unevenness is small B: Front contrast is less than 5 to 10% variation and slightly uneven C: Front contrast is 10% or more variation, 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 performed 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.

  The above results are shown in Tables 6 and 7.

  As is clear from Tables 6 and 7, the liquid crystal display devices 101 to 136 and 201 to 206 using the polarizing plates 101 to 136 and 201 to 206 of the present invention are liquid crystal displays using the comparative polarizing plates 137 to 150. As compared with the devices 137 to 150, it can be seen that the liquid crystal display device is extremely stable and excellent in durability, with excellent front contrast unevenness and no fluctuation in viewing angle even under conditions of changing humidity. In addition, the object of the present invention is achieved from the results of the liquid crystal display devices 137 to 143 using the comparative compounds C-001, C-002, C-003, C-004, C-005, C-006, and C-007. In order to do this, it is understood that a specific skeleton and substituent of the retardation developer are necessary.

  In addition, from the results of the liquid crystal display devices 135, 136, 144, and 145 using the polarizing plates 135, 136, 144, and 145 of the present invention, the retardation developer in the present invention is added in an increased amount to produce a large phase difference. However, since it is compatible with cellulose ester, the polarizing plate of the present invention is found to be a practically excellent polarizing plate.

  The liquid crystal display devices 148 to 150 using the optical film that does not contain the retardation developer have poor front contrast unevenness and viewing angle deterioration, and do not function as a liquid crystal display device.

Claims (9)

An optical film containing a cellulose ester, wherein the optical film contains a compound represented by the following general formula (1).
(In the formula, A, B and C represent a ring structure, and R _1, R ₂ and R ₃ represent a heterocyclic group, an alkyl group, a cycloalkyl group, an alkyloxy group, an aryloxy group, an aryloxycarbonyl group, an arylcarbonyl group. An oxy group, an acyl group, an acyloxy group, an amino group, an imide group, a carboxy group, a cyano group, an amide group, a carbamoyl group, an alkylthio group, and an arylthio group, n and m represent an integer of 0 to 5, and p represents 0. Represents an integer of ˜4, X represents an oxygen atom or a sulfur atom.) The optical film according to claim 1, wherein the compound represented by the general formula (1) is represented by the following general formula (2).
(In the formula, R ₁₁ and R ₂₂ and R ₃₃ are a heterocyclic group, an alkyl group, a cycloalkyl group, an alkyloxy group, an aryloxy group, an aryloxycarbonyl group, an arylcarbonyloxy group, an acyl group, an acyloxy group, and an amino group. , An imide group, a carboxy group, a cyano group, an amide group, a carbamoyl group, an alkylthio group, and an arylthio group, n ₁ and m ₁ represent an integer of 0 to 5, and p ₁ represents an integer of 0 to 4. X ₁ represents an oxygen atom or a sulfur atom.)   The optical film according to claim 1, wherein X in the general formula (1) is an oxygen atom.   The LogP value of the compound represented by said general formula (1) is 2.0-9.0, The optical film of any one of Claims 1-3 characterized by the above-mentioned. The optical film according to any one of claims 1 to 4, wherein the cellulose ester simultaneously satisfies the following formulas (a) and (b).
Formula (a) 1.5 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
(In the formula, X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the propionyl group or butyryl group, or a mixture thereof.)   The optical film according to claim 1, wherein the optical film has a thickness in the range of 20 to 60 μm. Retardation Ro value represented by a following formula is in the range of 20-150 nm, Rth value is in the range of 70-300 nm, The optical film of any one of Claims 1-6 characterized by the above-mentioned.
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 is a measured value at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, respectively, and d (nm) represents the thickness of the optical film. )   A polarizing plate comprising the optical film according to claim 1 on at least one surface of a polarizer.   A liquid crystal display device comprising the polarizing plate according to claim 8 on at least one surface of a liquid crystal cell.