JP2012177017A - Cellulose ester resin composition and optical film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide cellulose ester resin composition that provides high birefringence and achieves a thin film of an optical film, and the optical film using the same.SOLUTION: The cellulose ester resin composition is used, which contains: a cellulose acylate (A) in which a substitution degree of an acetyl group is in the range of 0.1-2.2, a substitution degree of a propionyl group or a butyryl group is in the range of 0.5-2.7, a substitution degree of a hydroxy group is in the range of 0-1, and the sum of these substitution degrees is 3; and an ester compound (B), wherein the ester compound (B) is an ester compound obtained by performing an esterification reaction of alkylenediol (b1), an aromatic dicarboxylic acid (b2), which is terephthalic acid or naphthalenedicarboxylic acid, or a dialkyl ester compound thereof, and an aromatic monocarboxylic acid (b3) or an alkyl ester compound thereof.

Description

  The present invention relates to a cellulose ester resin composition that can be used as a material for an optical film such as a retardation film used in a liquid crystal display, and an optical film using the same.

  In recent years, the demand for liquid crystal displays (hereinafter abbreviated as “LCD”) such as mobile terminals, tablet terminals, personal computer monitors, and liquid crystal televisions is increasing. LCD is a device that displays light by controlling light transmission using light rotation and liquid crystal birefringence, and switching between light and dark. An optical film such as a retardation film is used.

  As the polarizing plate, usually, a polarizer film obtained by stretching a film of polyvinyl alcohol (hereinafter abbreviated as “PVA”) to which iodine is added is attached with a protective film on both sides. . As the polarizer protective film, a cellulose ester resin film having generally high transparency, moderate strength, and excellent adhesiveness with PVA is used.

A typical example of the retardation film is a quarter-wave plate, and has a function of converting the polarization state of light by having a large optical anisotropy. The magnitude of this optical anisotropy can be expressed by the following formula as a retardation value of the film.
Phase difference (nm) = birefringence Δn × thickness d (nm)
Birefringence Δn = Nx−Ny
(However, Nx: Refractive index of slow axis in film plane, Ny: Refractive index of fast axis in film plane, Nx> Ny)

  For example, a quarter-wave plate can convert linearly polarized light into circularly-polarized light by having a phase difference value that is ¼ of the wavelength. In the current retardation film, polycarbonate or the like which is a raw material of optical anisotropy is used in order to express a large retardation value.

  For the quarter-wave plate, ideally, a film having a phase difference of a quarter wavelength at all wavelengths in the visible light region is required (for example, linearly polarized light having a wavelength of 588 nm is converted into circularly polarized light. (The phase difference value required for this is 147 nm). In order to satisfy this performance, the quarter wavelength plate is required to control birefringence wavelength dispersion in addition to the retardation value. Conventionally, a polycarbonate resin used as a wave plate has a characteristic that the birefringence decreases as the measurement wavelength becomes longer. When a film having such a characteristic is used, for example, the retardation value is 1 at 588 nm. Even when the wavelength is optimized for / 4 wavelength, the phase difference value is shifted from the ¼ wavelength on the short wavelength side and the long wavelength side, which causes problems such as light leakage of the LCD. In order to solve this problem, a film having a characteristic (reverse wavelength dispersion) in which birefringence increases as the measurement wavelength becomes longer is required.

  By the way, the laminated body which combined the polarizing plate and the quarter wavelength plate is called a circularly-polarizing plate, and is important in the mobile terminal use whose demand is increasing more and more. The circularly polarizing plate is an essential member for a reflective LCD or a transflective LCD with good visibility under external light, and is used for preventing external light reflection of an OLED display device that is a self-luminous display element. .

  Due to the recent demand for cost reduction and thickness reduction of LCDs, members are also actively studied for circularly polarizing plates.

  Here, the cellulose ester resin is known to exhibit birefringent reverse wavelength dispersibility, and is suitable for quarter wave plate applications. Moreover, since it is the same material as the conventional polarizer protective film, cost reduction and thickness reduction by combining the members can be expected. Furthermore, among cellulose ester resins, cellulose acetate propionate, cellulose acetate butyrate, and the like can use a melt-extrusion method with high productivity as a film forming method, and have an advantage that they can be produced at low cost.

  With the recent thinning of LCDs, there has been a demand for thinner retardation films. As described above, since the retardation value of the retardation film is determined by the product of the birefringence and the thickness of the film, the birefringence Δn is increased in order to reduce the thickness and obtain an equivalent retardation value. It will be necessary. Thermal stretching is known as a technique for increasing the birefringence of a resin film, but it has been difficult to develop birefringence in an isotropic cellulose ester resin.

  Therefore, as a technique for developing birefringence in a cellulose ester resin, for example, by adding a specific compound to cellulose acetate propionate into a film by a melt extrusion method, and increasing the birefringence by thermally stretching the film. (For example, refer to Patent Documents 1 and 2). However, the birefringence obtained by these methods is low, and the film cannot be thinned.

JP 2008-291246 A JP2011-21182A

  A problem to be solved by the present invention is to provide a cellulose ester resin composition capable of achieving high birefringence and thinning an optical film by thermally stretching a film mainly composed of a cellulose ester resin. It is providing the optical film using this.

  As a result of earnest research, the present inventors have blended an ester compound obtained by esterifying an alkylene diol, a specific aromatic dicarboxylic acid or an alkyl ester thereof, and an aromatic monocarboxylic acid or an alkyl ester thereof. The specific cellulose acylate resin composition has been found to be able to achieve high birefringence and to reduce the thickness of the retardation film by thermally stretching a film made of the resin composition. .

  That is, in the present invention, the substitution degree of the acetyl group is in the range of 0.1 to 2.2, the substitution degree of the propionyl group or the substitution degree of the butyryl group is in the range of 0.5 to 2.7, A cellulose ester resin composition containing a cellulose acylate (A) and an ester compound (B) having a substitution degree in the range of 0 to 1 and a total of these substitution degrees of 3, wherein the ester compound (B ) Is an esterification reaction of an alkylene diol (b1), an aromatic dicarboxylic acid (b2) which is terephthalic acid or naphthalenedicarboxylic acid or a dialkyl ester compound thereof, and an aromatic monocarboxylic acid (b3) or an alkyl ester compound thereof. The present invention relates to a cellulose ester resin composition and an optical film comprising the resin composition, wherein the cellulose ester resin composition is an ester compound obtained by That.

  The cellulose ester resin composition of the present invention can be easily formed into a film by a melt extrusion method, and an optical film having high birefringence can be obtained by thermally stretching the film. Therefore, the optical film comprising the cellulose ester resin composition of the present invention can be used for various optical films, and is particularly useful as a retardation film used for a circularly polarizing plate.

  The cellulose acylate (A) used in the cellulose ester resin composition of the present invention is obtained by esterifying part or all of the hydroxyl groups of cellulose obtained from cotton linter, wood pulp, kenaf and the like. Among these, a film obtained by using cellulose ester resin obtained by esterifying cellulose obtained from cotton linter is easy to peel off from the metal support constituting the film production apparatus, and improves the production efficiency of the film. It is preferable because it becomes possible.

  The cellulose molecule is a polysaccharide in which D-glucose, which is a basic unit, is connected in a straight chain with β-1,4 bonds. The glucose unit constituting cellulose has three hydroxyl groups at positions 2, 3, and 6, and these hydroxyl groups can be esterified. The esterification of cellulose can be performed by a known method. For example, cellulose is treated with a strong caustic soda solution and then acylated with an acid anhydride. The degree of substitution of the obtained cellulose acylate is about 3. By hydrolyzing this, a cellulose acylate having the desired degree of substitution can be produced. The type and degree of substitution of the cellulose acylate substituent can be determined by ASTM-D817.

  The cellulose acylate (A) has an acetyl group substitution degree in the range of 0.1 to 2.2 and a propionyl group substitution degree or a butyryl group substitution degree in the range of 0.5 to 2.7. The substitution degree of the hydroxyl group is in the range of 0 to 1, and the total of these substitution degrees is 3. Since the birefringence develops well, the substitution degree of the acetyl group is in the range of 0.1 to 1.5, and the substitution degree of the propionyl group or the substitution degree of the butyryl group is 1.0 to 2.7. More preferred is a range in which the degree of substitution of hydroxyl groups is in the range of 0 to 1 and the sum of these degrees of substitution is 3. Specific examples of the cellulose acylate (A) include cellulose acetate propionate and cellulose acetate butyrate.

  The number average molecular weight of the cellulose acylate (A) is preferably from 30,000 to 200,000, more preferably from 50,000 to 100,000, since the mechanical properties are good.

  The ester compound (B) used in the cellulose ester resin composition of the present invention comprises an alkylene diol (b1), an aromatic dicarboxylic acid (b2) that is terephthalic acid or naphthalenedicarboxylic acid, or a dialkyl ester compound thereof, and an aromatic monocarboxylic acid. It is an ester compound obtained by esterifying the acid (b3) or its alkyl ester compound.

  A main structure of the ester compound (B) is a structure represented by the following general formula (I).

（上記一般式（Ｉ）中のＲはアルキレンジオール（ｂ１）の残基を表し、Ｔは芳香族ジカルボン酸（ｂ２）の残基を表し、Ａは芳香族モノカルボン酸（ｂ３）の残基を表す。また、ｎは繰返し数を表し、０以上の整数である。）

(R in the general formula (I) represents a residue of an alkylene diol (b1), T represents a residue of an aromatic dicarboxylic acid (b2), and A represents a residue of an aromatic monocarboxylic acid (b3). In addition, n represents the number of repetitions and is an integer of 0 or more.)

  The above “residue” means the following. The “residue” of the alkylene diol (b1) represents the remaining organic group excluding the two hydroxyl groups that the alkylene diol (b1) has before the reaction. The “residue” of the aromatic dicarboxylic acid (b2) represents the remaining organic group excluding the carboxyl group of the aromatic dicarboxylic acid (b2).

  Examples of the alkylene diol (b1) include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, , 8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, and other linear alkylene diols; propylene glycol (1,2-propanediol) ), 2-methyl-1,3-propanediol, neopentyl glycol, 3,3-diethyl-1,3-propanediol, 3,3-dibutyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 2,3- Nthanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,4-pentanediol, 1,2-hexanediol, 1,3- Branched alkylene diols such as hexanediol, 1,4-hexanediol, 1,5-hexanediol; 1,4-cyclohexanedimethanol, cyclohexanedimethanol, hydrogenated bisphenol A, diethylene glycol, dipropylene glycol, triethylene glycol, Other diols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexylene glycol, bisphenol A, ethylene oxide adduct of bisphenol A, propylene oxide adduct, and the like can be mentioned. These alkylene diols (b1) can be used alone or in combination of two or more. Among these alkylene diols (b1), since the compatibility with the cellulose ester resin is good, linear or branched alkylene diols having 2 to 12 carbon atoms are preferable, and those having 2 to 6 carbon atoms. A linear or branched alkylene diol is more preferable. Further, among linear or branched alkylene diols having 2 to 6 carbon atoms, high birefringence can be imparted to the optical film, so that propylene glycol, 2-methyl-1,3-propanediol and 3-methyl- 1,5-pentanediol is preferred.

  In the present invention, a monoalcohol or a polyhydric alcohol may be used in addition to the above alkylene diol (b1) within a range not impairing the effects of the present invention. Examples of the monoalcohol include methanol, ethanol, 1-butanol, 2-butanol, hexanol, cyclohexanol, pentyl alcohol, octyl alcohol, lauryl alcohol, methyl lactate, and ethyl lactate. Examples of the polyhydric alcohol include glycerin, sorbitol, ribitol, pentaerythritol, dipentaerythritol and the like. These monoalcohols and polyhydric alcohols can be used alone or in combination of two or more. Further, in order to impart high birefringence to the optical film comprising the cellulose ester resin composition of the present invention, the alkylene diol (b) is added to the alkylene diol (b1) in a total of 100 parts by mass of the monoalcohol or polyhydric alcohol. The amount of b1) used is preferably 95 parts by mass or more.

  The aromatic dicarboxylic acid (b2) or its dialkyl ester compound used in the present invention is terephthalic acid or naphthalene dicarboxylic acid, and its dialkyl ester compound. These aromatic dicarboxylic acids can be used alone or in combination of two or more.

  When the dialkyl ester compound of the aromatic dicarboxylic acid (b2) is used, examples of the alkyl group include those having 1 to 8 carbon atoms, and those having 3 or more carbon atoms may be linear alkyl groups. It may be a branched alkyl group. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a cyclohexyl group, a heptyl group, and an octyl group. Two alkyl groups may be the same as or different from each other.

  Specific examples of the dialkyl ester compound of terephthalic acid include dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, dibutyl terephthalate, dipentyl terephthalate, dihexyl terephthalate, and diheptyl terephthalate.

  Specific examples of the dialkyl ester compound of naphthalene dicarboxylic acid include dimethyl naphthalene dicarboxylate, diethyl naphthalene dicarboxylate, dipropyl naphthalene dicarboxylate, dibutyl naphthalene dicarboxylate, dipentyl naphthalene dicarboxylate, dihexyl naphthalene dicarboxylate, diheptyl naphthalene dicarboxylic acid Etc.

  Of the above aromatic dicarboxylic acids (b2) or dialkyl ester compounds thereof, naphthalenedicarboxylic acid or dialkyl ester compounds thereof are preferred. Specifically, 1,4-naphthalenedicarboxylic acid or dialkyl ester compounds thereof, 1,5 -Naphthalenedicarboxylic acid or its dialkyl ester compound, 1,8-naphthalenedicarboxylic acid or its dialkyl ester compound, 2,3-naphthalenedicarboxylic acid or its dialkyl ester compound, 2,6-naphthalenedicarboxylic acid or its dialkyl ester compound are preferred . Among these, 2,6-naphthalenedicarboxylic acid or a dialkyl ester compound thereof is more preferable, and dimethyl 2,6-naphthalenedicarboxylic acid is more preferable.

  Furthermore, in the production of the ester compound (B), other dicarboxylic acids or their alkyl ester compounds or carbonate compounds can be used in combination as long as the effects of the present invention are not impaired. As said dicarboxylic acid or its alkylester compound, aliphatic dicarboxylic acid or aromatic dicarboxylic acid, or these alkylester compounds can be used. Examples of the aliphatic dicarboxylic acid or its alkyl ester compound include succinic acid, dimethyl succinate, glutaric acid, dimethyl glutarate, adipic acid, dimethyl adipate, diethyl adipate, dibutyl adipate, pimelic acid, dimethyl pimelate. , Suberic acid, dimethyl suberate, azelaic acid, dimethyl azelate, sebacic acid, dimethyl sebacate, decanedicarboxylic acid, dimethyl decanedicarboxylate, cyclohexanedicarboxylic acid, dimethyl cyclohexanedicarboxylate, dimer acid, dimethyl dimer, fumaric acid, And dimethyl fumarate. Examples of the aromatic dicarboxylic acid or its alkyl ester compound include phthalic acid, dimethyl phthalate, isophthalic acid, dimethyl isophthalate and the like. Furthermore, examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, and dibutyl carbonate. These other dicarboxylic acids or their alkyl ester compounds or carbonate compounds can be used alone or in combination of two or more. In order to impart high birefringence to the optical film comprising the cellulose ester resin composition of the present invention, the aromatic dicarboxylic acid is contained in a total of 100 parts by mass of the aromatic dicarboxylic acid compound (b2) and other dicarboxylic acids. The amount of the acid compound (b2) used is preferably 95 parts by mass or more.

  The aromatic monocarboxylic acid (b3) or an alkyl ester compound thereof used in the present invention is a compound having one carboxyl group in the aromatic ring or an alkyl ester compound. Among the aromatic monocarboxylic acids (b3), benzoic acid or a derivative thereof is preferable. Derivatives of benzoic acid include, for example, dimethyl benzoic acid, trimethyl benzoic acid, tetramethyl benzoic acid, ethyl benzoic acid, propyl benzoic acid, butyl benzoic acid, cumic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, Examples include p-toluic acid, ethoxybenzoic acid, propoxybenzoic acid, methoxybenzoic acid, dimethoxybenzoic acid, trimethoxybenzoic acid, cyanobenzoic acid, hydroxybenzoic acid, and cinnamic acid. These aromatic monocarboxylic acids (b3) or alkyl ester compounds thereof can be used alone or in combination of two or more. Of these, p-toluic acid and benzoic acid are preferable because deterioration of the resin composition at high temperature melting can be prevented and compatibility with the cellulose ester resin is excellent.

  The ester compound (B), which is an additive for cellulose ester resin of the present invention, contains, in a reactor, an alkylene diol (b1), an aromatic dicarboxylic acid (b2) that is terephthalic acid or naphthalenedicarboxylic acid, or a dialkyl ester compound thereof. The aromatic monocarboxylic acid (b3) or an alkyl ester compound thereof is charged and heated for esterification reaction.

  The reaction equipment used for producing the ester compound (B) is preferably a reaction equipment corresponding to pressurization and depressurization, equipped with a reactor, a stirrer, a rectifying column, a reflux condenser, a pump for depressurizing, and the like. Other common devices can be used.

  In producing the ester compound (B), an esterification catalyst is preferably used for the purpose of promoting the esterification reaction. Examples of the esterification catalyst include at least one metal or organometallic compound selected from the group consisting of Group 2, Group 3, Group 12, Group 13, and Group 14 of the Periodic Table. More specifically, for example, metals such as titanium, tin, zinc, aluminum, zirconium, magnesium, hafnium, germanium; titanium tetraisopropoxide, titanium tetrabutoxide, titanium oxyacetylacetonate, tin octoate, 2-ethyl Examples thereof include metal compounds such as hexanetin, acetylacetonate zinc, zirconium tetrachloride, zirconium tetrachloride tetrahydrofuran complex, hafnium tetrachloride, hafnium tetrachloride, hafnium tetrachloride complex, germanium oxide, and tetraethoxygermanium. Among these, titanium alkoxides are preferable because the reactivity can be improved, the handling is easy, and the storage stability of the ester compound (B) obtained by the esterification reaction is good. It is preferable to use titanium tetraisopropoxide, titanium tetrabutoxide, titanium oxyacetylacetonate or the like.

  The amount of the esterification catalyst used may be an amount that can control the esterification reaction and can suppress the coloring of the resulting ester compound (B). The alkylene diol (b1) and terephthalic acid or A range of 10 to 1,000 ppm is preferable with respect to the total amount of the aromatic dicarboxylic acid (b2) or its dialkyl ester compound which is naphthalenedicarboxylic acid and the aromatic monocarboxylic acid (b3) or its alkyl ester compound, A range of ˜500 ppm is more preferred, and a range of 30 to 300 ppm is particularly preferred. Since coloring of the ester compound (B) lowers the transparency of the film, it is necessary to pay particular attention to the optical film application that requires high transparency.

  When the ester compound (B) is produced, the esterification catalyst is added to the reactor with the alkylene diol (b1) and the aromatic dicarboxylic acid (b2) which is terephthalic acid or naphthalenedicarboxylic acid or a dialkyl ester thereof. The compound and the aromatic monocarboxylic acid (b3) or its alkyl ester compound may be added at the same time, or may be added during the temperature increase or at the start of pressure reduction, and the esterification catalyst is divided. It may be added.

  When the alkylene diol (b1) is reacted with the aromatic dicarboxylic acid (b2) or dialkyl ester compound thereof, which is terephthalic acid or naphthalenedicarboxylic acid, and the aromatic monocarboxylic acid (b3) or alkyl ester compound thereof. In addition, for the purpose of branching and increasing the molecular weight of the ester compound (B) within a range not inhibiting the effect of the present invention, a trivalent or higher polyvalent such as glycerin, pentaerythritol, trimellitic acid, pyromellitic acid, etc. Alcohol or carboxylic acid; polyisocyanates such as hexamethylene diisocyanate may also be used.

  The reaction temperature for producing the ester compound (B) is as follows. The alkylene diol (b1) as a raw material, the aromatic dicarboxylic acid (b2) that is terephthalic acid or naphthalenedicarboxylic acid, or a dialkyl ester compound thereof, 120 to 300 ° C. because the reaction can be promoted while suppressing the evaporation and sublimation of the carboxylic acid (b3) or its alkyl ester compound, and the thermal decomposition and coloring of the ester compound (B) produced by the reaction can be suppressed. The range of 150 degreeC-280 degreeC is more preferable. Further, the reaction time for producing the ester compound (B) is preferably 2 hours or more, and more preferably in the range of 4 to 100 hours.

  Furthermore, when manufacturing the said ester compound (B), it is preferable to carry out under reduced pressure from the middle of reaction for the objective of removing the unreacted raw material and a low molecular-weight product, or the objective of promoting reaction. The degree of vacuum when producing the ester compound (B) is preferably 3,000 Pa or less because unreacted raw materials and low molecular weight products can be removed quickly and the reaction can be promoted. 2,000 Pa or less is more preferable, and a range of 10 to 1,000 Pa is more preferable.

  As the ester compound (B), different ester compounds (B) may be produced separately and then used together. In addition, the ester compound (B) used in the present invention may be mixed with the cellulose acylate (A) to obtain the cellulose ester resin composition of the present invention within a range that does not impair the effects of the present invention. For example, you may mix | blend an additive with ester compound (B). Examples of the additive that can be added to the ester compound (B) include a catalyst deactivator for deactivating the catalytic activity of the esterification catalyst, and an antioxidant for suppressing coloring of the ester compound (B). It is done.

  Examples of the catalyst deactivator include chelating agents, and organic chelating agents or inorganic chelating agents can be used. Examples of organic chelating agents include amino acids, phenols, hydroxycarboxylic acids, diketones, amines, oximes, phenanthrolines, pyridine compounds, dithio compounds, diazo compounds, thiols, porphyrins, and nitrogen as a coordinating atom. Examples thereof include phenols having atoms and carboxylic acids. Examples of the inorganic chelating agent include phosphorus compounds such as phosphoric acid, phosphoric acid ester, phosphorous acid, and phosphorous acid ester. These chelating agents include the alkylene diol (b1), an aromatic dicarboxylic acid (b2) that is terephthalic acid or naphthalenedicarboxylic acid, or a dialkyl ester compound thereof, and an aromatic monocarboxylic acid (b3) or an alkyl ester compound thereof. It is preferable to add and use in the range of 10-2,000 ppm with respect to the total amount.

  The hydroxyl value of the ester compound (B) obtained by the above production method is preferably in the range of 0 to 40, and preferably in the range of 0 to 30 because it can prevent deterioration of the resin composition at high temperature melting. Are more preferable, and those in the range of 0 to 20 are more preferable. This hydroxyl value is derived from the terminal hydroxyl group of the ester compound (B), that is, the hydroxyl group of the alkylene diol (b1) used as a raw material.

  The number average molecular weight of the ester compound (B) has good compatibility with the cellulose acylate (A), and the smoothness and transparency of the film prepared from the cellulose ester resin composition of the present invention are good. Therefore, the range of 300 to 5,000 is preferable, the range of 350 to 3,000 is more preferable, and the range of 400 to 2,000 is more preferable.

  In addition, the number average molecular weight of the ester compound (B) in the present invention is measured using a gel permeation chromatograph (GPC) using tetrahydrofuran (THF) as an eluent, and converted into standard polystyrene. Obtainable. The measurement conditions are as follows.

[Measurement conditions of number average molecular weight (Mn) of ester compound (B)]
Measuring device: High-speed GPC device “HLC-8320GPC” manufactured by Tosoh Corporation
Column: “TSK GARDCOLUMN SuperHZ-L” manufactured by Tosoh Corporation
+ "TSK gel SuperHZM-M" manufactured by Tosoh Corporation
+ "TSK gel SuperHZM-M" manufactured by Tosoh Corporation
+ Tosoh Corporation “TSK gel SuperHZ-2000”
+ Tosoh Corporation “TSK gel SuperHZ-2000”
Detector: RI (differential refractometer)
Data processing: “EcoSEC Data Analysis version 1.07” manufactured by Tosoh Corporation
Column temperature: 40 ° C
Developing solvent: Tetrahydrofuran Flow rate: 0.35 mL / min Measurement sample: 15 mg of a sample was dissolved in 10 ml of tetrahydrofuran, and the obtained solution was filtered through a microfilter to obtain a measurement sample.
Sample injection volume: 20 μl
Standard sample: The following monodisperse polystyrene having a known molecular weight was used according to the measurement manual of “HLC-8320GPC”.

(Monodispersed polystyrene)
“A-300” manufactured by Tosoh Corporation
“A-500” manufactured by Tosoh Corporation
"A-1000" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
“F-1” manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
“F-4” manufactured by Tosoh Corporation
“F-10” manufactured by Tosoh Corporation
“F-20” manufactured by Tosoh Corporation
“F-40” manufactured by Tosoh Corporation
“F-80” manufactured by Tosoh Corporation
“F-128” manufactured by Tosoh Corporation
“F-288” manufactured by Tosoh Corporation

  The cellulose ester resin composition of the present invention contains the cellulose acylate (A) and the ester compound (B). The amount of the cellulose acylate (A) and the ester compound (B) in the cellulose ester resin composition of the present invention is such that a sufficiently high birefringence is obtained, and the film prepared with the cellulose ester resin composition of the present invention is used. Since transparency becomes favorable, what contained the said ester compound (B) in 0.5-50 mass parts with respect to 100 mass parts of said cellulose acylates (A) is preferable, and 3-40 masses Those contained in the range of parts are more preferred. What contained in the range of 5-30 mass parts is further more preferable.

  Moreover, the cellulose-ester resin composition of this invention can mix | blend various additives other than the said cellulose acylate (A) and ester compound (B) in the range which does not impair this invention.

  Examples of the additive include additives such as a modifier (including a plasticizer), an ultraviolet absorber, a retardation increasing agent, a thermoplastic resin, a matting agent, a deterioration preventing agent, and a dye.

  Examples of the modifier (including a plasticizer) include phosphate esters such as triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate; dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, and the like. Phthalic acid esters of; ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, trimethylolpropane tribenzoate, pentaerythritol tetraacetate, tributyl acetylcitrate and the like.

  Examples of the ultraviolet absorber include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. It is preferable that the compounding quantity of this ultraviolet absorber is the range of 0.01-2 mass parts with respect to 100 mass parts of said cellulose-ester resin (B).

  The retardation increasing agent is not particularly limited as long as the retardation value increases, and examples thereof include a compound having a 1,4-cyclohexanedicarboxylic acid ester compound and a 1,3,5-triazine ring. It is done. The blending amount of the retardation increasing agent is preferably in the range of 0.01 to 20 parts by mass, more preferably in the range of 1 to 10 parts by mass with respect to 100 parts by mass of the cellulose ester resin (B).

  Examples of the thermoplastic resin include polyester resins (for example, polyethylene terephthalate, polymethyl methacrylate, etc.), polycarbonate resins, polyester ether resins, polyurethane resins, epoxy resins, toluenesulfonamide resins, and the like.

  Examples of the matting agent include silicon oxide, titanium oxide, aluminum oxide, calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, kaolin, and talc. The amount of the matting agent is preferably in the range of 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the cellulose ester resin (B).

  Examples of the deterioration inhibitor include hindered phenol antioxidants, acid scavengers, hindered amine light stabilizers, peroxide decomposers, radical inhibitors, metal deactivators, and the like. In particular, for stabilizing at the time of heat melting when producing a film, a hindered phenol antioxidant, an acid scavenger, a hindered amine light stabilizer and the like are blended in the cellulose ester resin composition of the present invention as a deterioration inhibitor. It is preferable to do.

  The said dye can be used as needed, The compounding quantity should just be a range which does not impair the effect of this invention.

  As a method for producing the cellulose ester resin composition of the present invention, there is a method in which the cellulose acylate (A) and the ester compound (B) are melt-kneaded with an internal mixer, a roll kneader, a single screw or twin screw extruder or the like. Can be mentioned. The mixing temperature at this time is preferably 120 to 300 ° C, more preferably 150 to 260 ° C.

  As a method for producing the cellulose ester resin composition of the present invention, there is a method in which the cellulose acylate (A) and the ester compound (B) are melt-kneaded with an internal mixer, a roll kneader, a single screw or twin screw extruder or the like. Can be mentioned. In this case, the melt kneading temperature is preferably in the range of 120 to 300 ° C, more preferably in the range of 150 to 260 ° C. In order to prevent deterioration of the raw material, the melt kneading time is preferably within 5 minutes. In addition, when the resin composition is produced, the smoothness and transparency of the film prepared with the cellulose ester resin composition of the present invention are improved, so that the volatile components such as water and organic solvent contained in each component are volatilized. It is preferable to dry and remove the components in advance.

  The cellulose ester resin composition of the present invention can be used as an optical film by forming it into a film.

  Examples of the method for forming the cellulose ester resin composition into a film include a method of forming a film by a compression molding method, a method of melt-kneading with an extruder or the like, and forming into a film using a T die or the like. Can be mentioned. When a film is produced by these molding methods, the molding temperature is preferably in the range of 120 to 300 ° C, more preferably in the range of 150 to 260 ° C.

  Moreover, the cellulose ester resin composition of the present invention can be dissolved in an organic solvent in which each component is dissolved, and a film can be produced by a solution casting method.

  As a method for producing a film by the solution casting method, for example, a cellulose ester resin composition is dissolved in an organic solvent, and the obtained resin solution is cast on a support such as a glass plate or a metal. There is a method in which about 50 to 80% by mass of the organic solvent contained in the cast resin solution is evaporated and then peeled and further dried to completely remove the organic solvent and obtain a film.

  The film thickness of the optical film of the present invention is preferably in the range of 40 to 300 μm, more preferably in the range of 40 to 120 μm from the viewpoint of thinning. Among the optical films, when the present invention is used as a quarter-wave plate for a circularly polarizing plate, if the film thickness is 40 μm, the strength as a polarizing plate can be maintained, and in the present invention, a quarter-wave plate if 120 μm. As a result, a sufficient phase difference can be obtained.

  The optical film obtained by the above production method can be subjected to a heat stretching treatment to adjust the retardation value that is important as the retardation film by causing the optical film to exhibit birefringence. As the stretching method, either uniaxial stretching that stretches in one of the MD direction or TD direction of the film according to the retardation characteristics to be imparted to the optical film; either biaxial stretching that stretches in both the MD or TD directions. Can be selected. When biaxial stretching is performed, any of sequential biaxial stretching and simultaneous biaxial stretching can be used. The stretching temperature is preferably in the range of 90 to 170 ° C. Moreover, since sufficient birefringence is obtained, the draw ratio is preferably in the range of 1.1 to 5 times.

  The optical film of the present invention can be applied to a melt film-forming method, and is extremely excellent in the expression of birefringence, so that it can be used for an optical film of a liquid crystal display device, for example. Here, examples of the optical film include a retardation film essential for a circularly polarizing plate, a polarizer protective film with viewing angle compensation, and the like. Since the optical film of the present invention is a cellulose ester resin, a conventional polarizer bonding process can be applied in the polarizing plate production process, and high birefringence can be easily imparted to the film, which is very advantageous industrially. .

  The present invention will be specifically described below with reference to examples and comparative examples. In addition, the acid value of the ester compound synthesize | combined in the following synthesis examples 1-10, a hydroxyl value, and a number average molecular weight are measured on condition of the following.

[Measurement conditions for acid value and hydroxyl value]
The acid value and hydroxyl value of each ester compound were measured according to JIS K 0070-1992.

[Measurement conditions for number average molecular weight (Mn)]
Measuring device: High-speed GPC device “HLC-8320GPC” manufactured by Tosoh Corporation
Column: “TSK GARDCOLUMN SuperHZ-L” manufactured by Tosoh Corporation
+ "TSK gel SuperHZM-M" manufactured by Tosoh Corporation
+ "TSK gel SuperHZM-M" manufactured by Tosoh Corporation
+ Tosoh Corporation “TSK gel SuperHZ-2000”
+ Tosoh Corporation “TSK gel SuperHZ-2000”
Detector: RI (differential refractometer)
Data processing: “EcoSEC Data Analysis version 1.07” manufactured by Tosoh Corporation
Column temperature: 40 ° C
Developing solvent: Tetrahydrofuran Flow rate: 0.35 mL / min Measurement sample: 15 mg of a sample was dissolved in 10 ml of tetrahydrofuran, and the obtained solution was filtered through a microfilter to obtain a measurement sample.
Sample injection volume: 20 μl
Standard sample: The following monodisperse polystyrene having a known molecular weight was used according to the measurement manual of “HLC-8320GPC”.

(Monodispersed polystyrene)
“A-300” manufactured by Tosoh Corporation
“A-500” manufactured by Tosoh Corporation
"A-1000" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
“F-1” manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
“F-4” manufactured by Tosoh Corporation
“F-10” manufactured by Tosoh Corporation
“F-20” manufactured by Tosoh Corporation
“F-40” manufactured by Tosoh Corporation
“F-80” manufactured by Tosoh Corporation
“F-128” manufactured by Tosoh Corporation
“F-288” manufactured by Tosoh Corporation

[Synthesis Example 1]
A four-necked flask having an internal volume of 3 liters equipped with a thermometer, a stirrer and a reflux condenser was charged with 524.3 g of dimethyl terephthalate, 468.4 g of propylene glycol, 732.7 g of benzoic acid and tetraisopropyl titanate 0 as an esterification catalyst. .121 g was charged, while stirring under a nitrogen stream, the temperature was raised stepwise until reaching 230 ° C., and the reaction was conducted for a total of 11 hours. After the reaction, unreacted propylene glycol is removed under reduced pressure at 200 ° C. to obtain an ester compound (B1) (acid value: 0.07, hydroxyl value: 4, number average molecular weight: 450) which is a room temperature and high viscosity liquid. It was.

[Synthesis Example 2]
A three-liter four-necked flask equipped with a thermometer, stirrer and reflux condenser was charged with 699.1 g of dimethyl terephthalate, 416.4 g of propylene glycol, 293.1 g of benzoic acid and tetraisopropyl titanate 0 as an esterification catalyst. 0.085 g was charged and the temperature was raised stepwise to 230 ° C. while stirring under a nitrogen stream, and the reaction was conducted for a total of 13 hours. After the reaction, unreacted propylene glycol is removed under reduced pressure at 200 ° C. to obtain an ester compound (B2) (acid value: 0.56, hydroxyl value: 19.7, number average molecular weight: 790) which is a solid at normal temperature. It was.

[Synthesis Example 3]
A three-liter four-necked flask equipped with a thermometer, stirrer and reflux condenser was charged with 883.5 g of dimethyl terephthalate, 451.1 g of propylene glycol, 158.8 g of benzoic acid and tetraisopropyl titanate 0 as an esterification catalyst. 0.090 g was charged and the temperature was raised stepwise to 230 ° C. while stirring under a nitrogen stream, and the reaction was allowed to proceed for a total of 20.5 hours. After the reaction, unreacted propylene glycol is removed under reduced pressure at 230 ° C. to obtain an ester compound (B3) (acid value: 1.06, hydroxyl value: 12.9, number average molecular weight: 1450) which is a solid at room temperature. It was.

[Synthesis Example 4]
A three-liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser was charged with 553.5 g of dimethyl terephthalate, 476.4 g of propylene glycol, 816.6 g of p-toluic acid, and tetraisopropyl titanate 0 as an esterification catalyst. .111 g was charged and the temperature was raised stepwise to 230 ° C. while stirring under a nitrogen stream, and the reaction was carried out for a total of 17 hours. After the reaction, unreacted propylene glycol is removed under reduced pressure at 195 ° C. to obtain an ester compound (B4) (acid value: 0.19, hydroxyl value: 11, number average molecular weight: 450), which is a normal viscosity liquid. It was.

[Synthesis Example 5]
In a four-necked flask with an internal volume of 2 liters equipped with a thermometer, a stirrer and a reflux condenser, 349.5 g of dimethyl terephthalate, 377.0 g of 2-methyl-1,3-propanediol, 488.5 g of benzoic acid and 0.073 g of tetraisopropyl titanate was charged as an esterification catalyst, and the temperature was raised stepwise to 230 ° C. while stirring under a nitrogen stream, and the reaction was conducted for a total of 13 hours. After the reaction, the unreacted 2-methyl-1,3-propanediol is removed under reduced pressure at 200 ° C., whereby the ester compound (B5) (acid value: 0.07, hydroxyl value: 13.3, Number average molecular weight: 490) was obtained.

[Synthesis Example 6]
In a three-liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser, 349.5 g of dimethyl terephthalate, 494.0 g of 3-methyl-1,5-pentanediol, 488.5 g of benzoic acid and 0.080 g of tetraisopropyl titanate was charged as an esterification catalyst, and the temperature was raised stepwise to 230 ° C. while stirring under a nitrogen stream, and reacted for a total of 12.5 hours. After the reaction, the unreacted 3-methyl-1,5-pentanediol is removed under reduced pressure at 200 ° C. to obtain an ester compound (B6) (acid value: 0.05, hydroxyl value: 15. 3, number average molecular weight: 510) was obtained.

[Synthesis Example 7]
In a four-necked flask having an internal volume of 3 liters equipped with a thermometer, a stirrer and a reflux condenser, 439.6 g of dimethyl 2,6-naphthalenedicarboxylate, 329.7 g of propylene glycol, 488.4 g of benzoic acid and an esterification catalyst As a starting material, 0.075 g of tetraisopropyl titanate was charged, and the temperature was raised stepwise to 230 ° C. while stirring under a nitrogen stream, and the reaction was carried out for a total of 15 hours. After the reaction, unreacted propylene glycol is removed under reduced pressure at 200 ° C. to obtain an ester compound (B7) (acid value: 0.16, hydroxyl value: 15.9, number average molecular weight: 470) which is a solid at room temperature. It was.

[Synthesis Example 8]
A three-liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser was charged with 600 g of succinic acid, 560 g of propylene glycol and 0.070 g of tetra n-butyl titanate as an esterification catalyst under a nitrogen stream. While stirring, the temperature was raised stepwise until it reached 220 ° C. and reacted for a total of 9 hours. After the reaction, unreacted propylene glycol is removed under reduced pressure at 220 ° C. to obtain an ester compound (B8) (acid value: 0.49, hydroxyl value: 72, number average molecular weight: 1,100) which is a liquid at room temperature. It was.

[Synthesis Example 9]
Into a 2-liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser is charged 370 g of phthalic anhydride, 433.2 g of propylene glycol, 610 g of benzoic acid and 0.170 g of tetraisopropyl titanate as an esterification catalyst. While stirring under a nitrogen stream, the temperature was raised stepwise until reaching 230 ° C., and the reaction was carried out for a total of 17 hours. After the reaction, unreacted propylene glycol was removed under reduced pressure at 200 ° C. to obtain an ester compound (B9) (acid value: 0.19, hydroxyl value: 10, number average molecular weight: 480) which is a liquid at normal temperature.

[Synthesis Example 10]
In a three-liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser, 415.4 g of isophthalic acid, 433.7 g of propylene glycol, 610.6 g of benzoic acid, and tetraisopropyl titanate as an esterification catalyst were added. 088 g was charged and the temperature was raised stepwise to 230 ° C. while stirring under a nitrogen stream, and the reaction was carried out for a total of 14 hours. After the reaction, unreacted propylene glycol is removed under reduced pressure at 200 ° C., whereby an ester compound (B10) which is a normal temperature high viscosity liquid (acid value: 0.30, hydroxyl value: 12.0, number average molecular weight: 470). Got.

Table 1 shows a summary of the raw material components, acid value, hydroxyl value and number average molecular weight of the ester compounds (B1) to (B10) obtained in Synthesis Examples 1 to 10. In addition, the symbol in Table 1 is as follows.
PG: propylene glycol 2MPD: 2-methyl-1,3-propanediol 3MPD: 3-methyl-1,5-pentanediol DMT: dimethyl terephthalate NDCM: dimethyl 2,6-naphthalenedicarboxylate SuA: succinic acid PA: anhydrous Phthalic acid iPA: Isophthalic acid BzA: Benzoic acid PTA: Palatoluic acid

  A cellulose ester resin composition was prepared by the following operation using the ester compounds (B1) to (B10) obtained in Synthesis Examples 1 to 10.

[Example 1]
Cellulose acetate propionate (“CAP-482-20” manufactured by Eastman Chemical Co., Ltd .; acetyl group substitution degree 0.2, propionyl group substitution degree 2.5, hydroxyl group substitution degree 0.3, number average molecular weight 75, 000; hereinafter abbreviated as “CAP”.) 100 parts by mass and 10 parts by mass of the ester compound (B1) obtained in Synthesis Example 1 were used at 200 ° C. The mixture was mixed at 30 rpm for 5 minutes to obtain a cellulose ester resin composition (1).

[Examples 2 to 8]
The same operations as in Example 1 were performed with the blending amounts shown in Table 2, and cellulose ester resin compositions (2) to (8) were obtained as Examples 2 to 8.

[Example 9]
In place of CAP used in Example 1, cellulose acetate butyrate (“CAB-381-20” manufactured by Eastman Chemical Co., Ltd .; substitution degree of acetyl group 1.0, substitution degree of butyryl group 1.7, substitution of hydroxyl group Degree 0.3, number average molecular weight 70,000; hereinafter abbreviated as “CAB”), the same operation as in Example 1 was performed to obtain a cellulose ester resin composition (9).

[Comparative Example 1]
100 parts by mass of CAP and 10 parts by mass of tricresyl phosphate (hereinafter abbreviated as “TCP”) were mixed at 200 ° C. and 30 rpm for 5 minutes using a lab plast mill (manufactured by Toyo Seiki Seisakusho Co., Ltd.). An ester resin composition (C1) was obtained.

[Comparative Examples 2 to 5]
The same operation as in Example 1 was performed with the blending amounts shown in Table 3, and cellulose ester resin compositions (C2) to (C4) were obtained as Comparative Examples 2 to 4. Moreover, the thing only of CAP was prepared as the comparative example 5 (it is set as the cellulose-ester resin composition (C5)).

(Production of evaluation film)
The cellulose ester resin compositions (1) to (9) and (C1) to (C5) obtained in Examples 1 to 9 and Comparative Examples 1 to 5 were molded with a compression molding machine heated to 200 ° C. And it cooled at 25 degreeC and obtained the film for evaluation about 200 micrometers thick. Next, using a heating uniaxial stretching machine (manufactured by UBM), a stretched film was obtained by uniaxial stretching at a stretching temperature shown in Table 2 or 3 so as to be twice the initial length. In addition, extending | stretching temperature was made into the temperature from which E 'by DMA measurement (10 Hz) of each cellulose-ester resin composition will be 10 Mpa.

(Measurement of birefringence of evaluation film)
In order to evaluate the performance of the stretched film obtained above as a retardation film, birefringence at 588 nm was measured with an automatic birefringence meter (“KOBRA-WR” manufactured by Oji Scientific Instruments).

(Calculation of 1 / 4λ retardation film thickness)
Using the birefringence value obtained above, the thickness in the case of a 1 / 4λ retardation film was calculated by the following formula (1). The phase difference value required for 1 / 4λ is 588/4 = 147 nm.

  Tables 2 and 3 show the measured values of birefringence and the calculated values of the thickness of the quarter-wave retardation film measured above.

The films produced using the cellulose ester resin compositions of Examples 1 to 9 of the present invention have a birefringence of 7.7 × 10 ⁻⁴ in Comparative Example 5 in which nothing is added, whereas 12. 7 × 10 ^{−4 to} 24.0 × 10 ⁻⁴ showed high birefringence, and it was found that a thinner film could be formed when a retardation film was used. In particular, Example 8 using 2,6-naphthalenedicarboxylic acid as the aromatic dicarboxylic acid (b2) exhibits a very high birefringence of 24.0 × 10 ⁻⁴ and is an extremely excellent material. I understood.

On the other hand, Comparative Example 1 using TCP as a conventional additive showed a relatively high birefringence of 11.4 × 10 ⁻⁴ . However, compared with Examples 1 to 8 of the present invention, the film was made thinner. Was insufficient.

In Comparative Example 2 using succinic acid which is an aliphatic dicarboxylic acid instead of the aromatic dicarboxylic acid (b2) used in the present invention, the birefringence is 4.3 × 10 ⁻⁴ , and only the CAP of Comparative Example 5 is used. It has been found that the birefringence is lower than that.

In Comparative Example 3 in which phthalic acid was used as the aromatic dicarboxylic acid, the birefringence was 9.9 × 10 ⁻⁴ , and the birefringence was slightly improved as compared with the CAP of Comparative Example 5 alone. It was enough.

In Comparative Example 4 in which isophthalic acid was used as the aromatic dicarboxylic acid, the birefringence was 8.9 × 10 ⁻⁴ , and the birefringence was slightly improved from that of Comparative Example 5 alone. It was insufficient.

Claims (7)

  The degree of substitution of the acetyl group is in the range of 0.1 to 2.2, the degree of substitution of the propionyl group or the degree of substitution of the butyryl group is in the range of 0.5 to 2.7, and the degree of substitution of the hydroxyl group is 0 to 1. A cellulose ester resin composition containing a cellulose acylate (A) and an ester compound (B) having a total degree of substitution of 3, wherein the ester compound (B) is an alkylene diol ( b1), an aromatic dicarboxylic acid (b2) which is terephthalic acid or naphthalenedicarboxylic acid or a dialkyl ester compound thereof, and an aromatic monocarboxylic acid (b3) or an alkyl ester compound thereof which is obtained by esterification A cellulose ester resin composition characterized by being:   The cellulose ester resin composition according to claim 1, wherein the alkylene diol (b1) is a linear or branched alkylene diol having 2 to 12 carbon atoms.   The cellulose ester resin composition according to claim 1 or 2, wherein the naphthalenedicarboxylic acid is 2,6-naphthalenedicarboxylic acid.   The cellulose ester resin composition according to any one of claims 1 to 3, wherein the aromatic monocarboxylic acid (b3) is benzoic acid or a derivative thereof.   The cellulose ester resin composition of any one of Claims 1-4 which contain 0.5-50 mass parts of said ester compounds (B) with respect to 100 mass parts of said cellulose acylates (A).   An optical film comprising the cellulose ester resin composition according to any one of claims 1 to 5.   An optical film obtained by heat-stretching the optical film according to claim 6.