JP2007152880A - Method for manufacturing optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical film by a melt extrusion process, which is free from the inclusion of a foreign substance generated following thermal decomposition and also from the phase difference non-uniformity in the film. <P>SOLUTION: This method for manufacturing the optical film comprises supplying an amorphous thermoplastic resin to a melt extrusion machine, filtering the resin by a filtering device after melting, and obtaining the optical film by the melt extrusion process for extruding the amorphous thermoplastic resin melt from a molding die, wherein the filtering device has a filter with 3 to 10 μm nominal filter precision and also 0.04 to 0.1 MPa shear stress value at the time of passage of the amorphous thermoplastic resin melt through the filter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an optical film produced by a melt extrusion method using a melt extruder.

  In recent years, liquid crystal display devices (LCDs) can be directly connected to IC circuits with low voltage and low power consumption, and in particular, can be thinned, so that word processors, personal computers, televisions, monitors, portable information terminals, etc. Widely used as a display device. The basic configuration of this LCD is, for example, in which polarizing plates are provided on both sides of a liquid crystal cell, and the polarizing plate allows only light of a polarization plane in a certain direction to pass through. Accordingly, the LCD plays an important role in visualizing the change in the orientation of the liquid crystal due to the electric field. That is, the performance of the LCD is greatly influenced by the performance of the polarizing plate.

  The polarizing plate generally has a structure in which both sides of a polarizer made of a polyvinyl alcohol film or the like on which iodine or dye is adsorbed and oriented are laminated with a transparent resin layer, and for this transparent resin layer, In addition to low birefringence, optical homogeneity is required.

  For this reason, in the case of a polarizer protective film for protecting a polarizer or a film substrate for a plastic liquid crystal display device in which the glass substrate is replaced with a resin film, 1) the phase difference represented by the product of birefringence and thickness is 2) The fact that the retardation of the film is difficult to change due to external stress, etc. 3) The unevenness of these retardations is small in the plane in the plane direction and the thickness direction, and 4) the planarity of the film surface. Required. That is, when the phase difference is large, the phase difference is changed by an external stress, the change of the phase difference in the surface is large, or the film surface is bad, the image quality of the liquid crystal display device is significantly lowered. That is, there are problems such as a color skip phenomenon in which the color is partially lightened and an image distortion. Therefore, an amorphous thermoplastic resin is suitable and frequently used as an optical film made of a thermoplastic resin used in a liquid crystal display device.

  As a method for producing an optical film using an amorphous thermoplastic resin, it has been produced by a solution casting method having excellent thickness uniformity. However, in recent years, it has been pointed out that the solvent casting method is contaminated with the environment by the solvent and the productivity is low, and the solution casting method is being changed to the melt extrusion method.

  However, in such a molding method by melt extrusion, the resin is processed by applying heat and shear, so that the resin undergoes thermal decomposition, hydrolysis, oxidative decomposition, gelation, etc., and branching reaction. When these foreign substances are contained in the molten resin, it has been a factor of productivity reduction, such as causing a surface defect of a molded product or a decrease in stretchability.

  Generally, in order to remove these foreign substances, if a powerful filtration process that can remove even fine foreign substances is added and installed, the residence time in the filtration process of the molten resin becomes longer, and instead, these decomposition reactions are promoted. As a result, only a large amount of foreign matters can be obtained in the molded product. In addition, in order to reduce the melt extrusion temperature as much as possible and suppress these decompositions in the molten state, melting below the melting point of the resin or in a supercooled state will certainly suppress decomposition, but the melt viscosity of the molten resin There is a problem that the pressure during filtration (filtering pressure) becomes abnormally high in the filtration process that should remove foreign substances, and the amount of resin passing is extremely reduced.

  These countermeasures have been studied, for example, by forming by a melt extrusion method, applying a specific vibration in a process close to the filtration process and reducing the melt viscosity, thereby producing a clean polymer free from thermal decomposition and gelation. A method of manufacturing using a normal high-precision filter medium filter is known (see, for example, Patent Document 1).

  When manufacturing an optical film by a melt extrusion method, a method is known in which the die is sealed with an inert gas at least after the heating of the die is started until the molten resin is extruded from the die (for example, (See Patent Document 2).

  The methods of Patent Document 1 and Patent Document 2 are effective methods for preventing foreign matter from being mixed due to decomposition because the resin is prevented from being decomposed by heating. However, in recent years, the demand for a protective film for a polarizing plate for liquid crystal used in a large-screen / high-quality liquid crystal display device as a monitor to replace CRT, which has been under development, has become strict. It is in an inadequate state for improvement of retardation unevenness (retardation unevenness) when manufactured by an extrusion method.

Under such circumstances, it is desired to develop a method for producing an optical film by a melt extrusion method in which no foreign matter is mixed with decomposition due to heating and there is no phase difference unevenness.
Japanese Patent Laid-Open No. 11-227025 JP 2004-322346 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing an optical film by a melt extrusion method that is free from foreign matter mixing with decomposition due to heating and has no phase difference unevenness. is there.

  The above object of the present invention has been achieved by the following constitution.

  1. After supplying amorphous thermoplastic resin to a melt extruder and melting it, it is filtered by a filtration device, and then manufactured by a melt extrusion method in which an amorphous thermoplastic resin melt is extruded from a molding die. In the method for producing a film, the filtration device has a filter with a nominal filtration accuracy of 3 to 10 μm, and the value of shear stress when the amorphous thermoplastic resin melt passes through the filter is 0.04 to 0. A method for producing an optical film, wherein the pressure is 1 MPa.

  2. 2. The method for producing an optical film as described in 1 above, wherein the amorphous thermoplastic resin melt contains at least one compound having a phenol structure and a phosphite structure in the molecule.

  3. 3. The method for producing an optical film as described in 2 above, wherein the compound having the phenol structure and the phosphite structure in the molecule is represented by the following general formula (I).

(In the general formula (I), R ¹ , R ² , R ⁴ , R ⁵ , R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. Represents an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, and R ³ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Represents a single bond, a sulfur atom or a —CHR ⁹ — group (R ⁹ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms). 8 represents an alkylene group or * —COR ¹⁰ — group (R ¹⁰ represents a simple bond or an alkylene group having 1 to 8 carbon atoms, and * represents that it is bonded to the oxygen side) Y and Z represent Either one is a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms, or 7 to 1 carbon atoms 2 represents an aralkyloxy group, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)
As a result of diligent investigations to achieve the above-mentioned problems, the inventors used a filter for removing foreign substances in the molten resin when manufacturing an optical film by a melt extrusion method. It was found that there was a difference in retardation difference (coefficient of variation (CV) of retardation (CV)) of the finished film depending on the flow rate, and that foreign matter was mixed depending on the flow rate.

  In order to increase production efficiency, the flow rate that passes through the filter should be reduced as the difference in phase difference (coefficient of variation of retardation (CV)) occurs and the bright spot failure of the product increases due to the increase in foreign matter. By increasing the shear stress generated when passing through the filter, the molten resin is kneaded better, the orientation of the resin becomes random, and the retardation unevenness (retardation variation coefficient (CV)) is uniform. However, it was estimated that when the shear stress becomes too high, the resin is decomposed and foreign matters are generated when passing through the filter.

  In contrast to these, the inventors have intensively studied, and as a result, filtered molten resin with a combination of a filter with a specific nominal filtration accuracy and a shear stress applied to the resin during filtration in a specific range. By preventing breakdown due to foreign matter, without lowering production efficiency, preventing decomposition due to stagnation during filtration, stabilizing the degree of resin mixing in each filtration lot, and making the resin orientation more random It has been found that the retardation unevenness (retardation coefficient of variation (CV)) is stabilized and improved, and the present invention has been achieved.

  We can provide a manufacturing method of optical film by melt extrusion method that does not contain foreign matter due to decomposition by heating and does not cause phase difference unevenness, improve production efficiency of optical film by melt extrusion method, It has become possible to improve the quality of polarizing plates used in liquid crystal display devices with higher screen quality.

  The embodiment of the present invention will be described with reference to FIGS. 1 and 2, but the present invention is not limited to this. In the present invention, the optical film is a functional film used for various display devices such as a liquid crystal display, a plasma display, and an organic EL display, and in particular, a polarizing plate protective film, a retardation film, an antireflection film, and a brightness enhancement film. In addition, an optical compensation film for expanding the viewing angle and the like are included. As an example of using these optical films, FIG. 1 illustrates a liquid crystal display device equipped with a polarizing plate using an optical film produced by the production method of the present invention as a polarizing plate protective film, an optical compensation film, and a polarizing plate.

  FIG. 1 is an exploded schematic view showing an example of a liquid crystal display device.

  In the figure, reference numeral 1 denotes a liquid crystal display device. The liquid crystal display device 1 has a configuration in which a polarizing plate 102 and a polarizing plate 103 are provided on both sides of a liquid crystal cell 101. The polarizing plate 102 (103) has a polarizing plate protective film 102b (103b) and an optical compensation film 102c (103c) with the polarizer 102a (103a) interposed therebetween.

  The present invention relates to a method for producing an optical film used as the polarizing plate protective film 102b (103b) and the optical compensation film 102c (103c) shown in the drawing by a melt extrusion method.

  FIG. 2 is a schematic view showing an example of a production apparatus for producing an optical film by a melt extrusion method.

  In the figure, 2 indicates a manufacturing apparatus. The manufacturing apparatus 2 includes a melt extruder 201, a T die 202, a cooling take-up machine 203, and a winder 204. The production apparatus used for the melt extrusion method is not particularly limited, and may be an apparatus to which an additional apparatus or the like is added in addition to the apparatus shown in the figure.

  The melt extruder 201 stabilizes the discharge speed from the die 202 of the main body 201a, the hopper 201b for supplying the amorphous thermoplastic resin to the main body 201a, and the amorphous thermoplastic resin melted by the main body 201a, and the optical extruder 201b. The gear pump 201c disposed to improve the thickness accuracy in the film flow direction, the filter 201d for removing foreign matter mixed in the molten amorphous thermoplastic resin, and the additive are uniformly mixed. And a mixer 201e. As shown in this figure, the amorphous thermoplastic resin melted by the main body 201a is widened by a T-die 202 through a filter 201d, extruded from a narrow gap at the tip, and cooled and solidified by a cooling roll 203a of a cooling take-up machine 203. To obtain an unstretched film. Then, after removing the ear | edge part of both ends, an optical film is manufactured by winding up with the winder 204. FIG.

  As the filter 201d, a sintered metal fiber filter having a nominal filtration accuracy of 3 to 10 μm is used. When the nominal filtration accuracy is less than 3μm, the pressure loss becomes very large, making it difficult to form a film. In addition, foreign matter increases and bright spot failure of the product increases, and bright spot failure of the product increases. Therefore, it is not preferable. When the nominal filtration accuracy exceeds 10 μm, the removal of the foreign matter is insufficient, so that the bright spot foreign matter of the product is increased and the phase difference unevenness (retardation variation coefficient (CV)) becomes large. Moreover, it is necessary to control with the gear pump 201c so that the value of the shear stress when the amorphous thermoplastic resin melt passes through the filter 201d having a nominal filtration accuracy of 3 to 10 μm is 0.04 to 0.1 MPa. . When the value of the shear stress is less than 0.04 MPa, the retardation change due to the presence or absence of the filter does not appear, and the required quality in recent years cannot be achieved. If the value of the shear stress exceeds 0.1 MPa, foreign matter contamination due to the shear stress increases and the bright spot failure of the product increases, which is not preferable.

  In addition, about the nominal filtration precision of the filter, it measured by the bubble point method (ASTM F316-86, JISK3832). The change in shear stress was determined by the following equation.

Shear stress = (filtration pressure × filter nominal filtration accuracy) / (filter thickness)
The filtration pressure was measured with a pressure sensor installed in the filtration device. The resin viscosity was measured with a flow tester CFT-500 manufactured by Shimadzu Corporation by changing the resin temperature and changing the additive type and amount. The flow rate was controlled by a gear pump installed on the upstream side of the filter. The thickness of the filter was measured using a caliper.

  The filter 201d is not particularly limited. For example, a single-layer metal mesh made of an alloy such as stainless steel called a screen mesh, a sintered metal filter in which a metal mesh made of an alloy such as stainless steel is laminated, and each layer is sintered, stainless steel Sintered metal fiber filters in which the contact points between the fibers are sintered with a wire mesh intricately knitted fine fibers, sintered metal filters in which metal powder is sintered, etc., among these, particularly sintered metal fiber filters Is preferably used. Further, it is desirable that the filter 201d has a structure such that overheating due to stagnation does not easily occur in the filter 201d.

  As shown in this figure, the following effect can be obtained by setting the value of the shear stress when the amorphous thermoplastic resin melt passes through the filter 201d having a nominal filtration accuracy of 3 to 10 μm to 0.04 to 0.1 MPa. Is obtained.

  1) It is possible to produce a stable optical film with no bright spot failure and no phase difference unevenness due to contamination by foreign matter due to shear stress, thereby improving production efficiency.

  2) It has become possible to improve the quality of polarizing plates used in next-generation large-screen / high-quality liquid crystal display devices.

  Next, general conditions when an optical film is produced using the melt extruder 201 shown in this figure are shown. The take-up speed of the cooling take-up machine 203 is preferably 5 m / min to 100 m / min in consideration of molecular orientation and birefringence.

  The melting temperature of the amorphous thermoplastic resin in the main body 201a may be appropriately selected according to the amorphous thermoplastic resin to be used. Among them, in order to avoid deterioration of the film appearance due to thermal decomposition of the molten resin, the resin is melted. After that, it is preferably maintained at 300 ° C. or less until it is discharged from the T die, and particularly preferably 290 ° C. or less.

  The temperature setting of the cooling roll 203a of the cooling take-up machine 203 is one of the important manufacturing conditions having a great influence on the appearance and optical characteristics of the obtained optical film. It is optimized in consideration of the balance of moldability. The surface temperature is measured with a differential scanning calorimeter (hereinafter referred to as DSC) at a heating rate of 10 ° C./min with respect to the glass transition temperature of the resin composition. The temperature is preferably −40 ° C. to + 20 ° C., more preferably −35 ° C. to + 10 ° C.

  The screw rotation speed of the main body 201a and the discharge amount from the T die can be appropriately selected according to the thickness of the optical film to be manufactured, the take-up speed, and the like. In order to suppress thermal decomposition and yellowing due to oxidation of the molten resin, it is preferable to purge or vacuum the inside of the hopper, the extruder cylinder, etc. with an inert gas such as nitrogen or argon.

  Examples of the extruder according to the present invention include, for example, a single-screw extruder, a co-rotating twin-screw extruder, a counter-rotating twin-screw extruder, a tandem extruder, and the like, but the mechanical properties of the resulting film From the viewpoint of optical properties, it is preferable to use a single screw extruder. If the amorphous thermoplastic resin used, additives, etc. contain volatile components such as water, the film appearance deteriorates when the optical film is extruded, so these extruders are used to remove volatile components. What was equipped with the vacuum vent, the hopper dryer, etc. is used suitably. In addition, the cylinder diameter, L / D, compression ratio, and screw design should generally be optimized according to the production speed, film dimensions, etc., especially when manufacturing optical films, to stabilize the discharge speed. At the same time, it may be optimized for the purpose of suppressing heat generation from friction and maintaining the resin temperature below the decomposition temperature.

  The temperature of the melt at the time of melt extrusion is usually in the range of 150 to 300 ° C, preferably in the range of 180 to 270 ° C, more preferably in the range of 200 to 250 ° C. The temperature of the melt is a value measured using a contact thermometer.

  When the optical film manufactured by the method for manufacturing an optical film of the present invention is used as a polarizing plate protective film, the optical film is particularly a film stretched in the width direction or the film forming direction. preferable. From the glass transition temperature (Tg) of the amorphous thermoplastic resin, the unstretched film is peeled from the cooling roll 203a of the cooling take-up machine 203 and the obtained unstretched film is passed through a plurality of roll groups and / or a heating device such as an infrared heater. It is preferable to heat within the range of Tg + 100 ° C. and to perform one-stage or multistage longitudinal stretching. Next, it is preferable that the amorphous thermoplastic resin film stretched in the longitudinal direction obtained as above is transversely stretched within a temperature range of Tg to Tg-20 ° C. and then heat-set.

  In the case of transverse stretching, it is preferable to perform transverse stretching while sequentially raising the temperature difference in the range of 1 to 50 ° C. in a stretched region divided into two or more because the distribution of physical properties in the width direction can be reduced. Further, after the transverse stretching, it is preferable that the film is held at a temperature not higher than the final transverse stretching temperature within a range of Tg-40 ° C. for 0.01 to 5 minutes because the distribution of physical properties in the width direction can be further reduced.

  In the heat setting, heat setting is usually performed for 0.5 to 300 seconds at a temperature higher than the final transverse stretching temperature and within a temperature range of Tg-20 ° C or lower. At this time, it is preferable to heat-fix while sequentially raising the temperature difference in the range of 1 to 100 ° C. in the region divided into two or more.

  The heat-set film is usually cooled to Tg or less, and clip holding portions at both ends of the film are cut and wound. At this time, it is preferable to perform a relaxation treatment of 0.1 to 10% in the horizontal direction and / or the vertical direction within the temperature range of the final heat setting temperature or lower and Tg or higher. Further, the cooling is preferably performed by gradually cooling from the final heat setting temperature to Tg at a cooling rate of 100 ° C. or less per second. Means for cooling and relaxation treatment are not particularly limited, and can be performed by a conventionally known means. In particular, it is preferable to carry out these treatments while sequentially cooling in a plurality of temperature ranges from the viewpoint of improving the dimensional stability of the film. The cooling rate is a value obtained by (T1-Tg) / t, where T1 is the final heat setting temperature and t is the time until the film reaches Tg from the final heat setting temperature.

  The optimum conditions of these heat setting conditions, cooling, and relaxation treatment conditions vary depending on the amorphous thermoplastic resin used, so the physical properties of the obtained biaxially stretched film are measured and adjusted appropriately to have desirable characteristics. To do so.

  As the amorphous thermoplastic resin according to the present invention, the amorphous thermoplastic resin is not particularly limited as long as it is an amorphous thermoplastic resin having excellent transparency. For example, a thermoplastic saturated norbornene resin or polycarbonate Resin, polysulfone resin, polyethersulfone resin, polymethyl methacrylate resin, polyarylate resin, styrene resin, polyvinyl chloride resin, polyester resin, cellulose resin, cyclic olefin resin, etc. These amorphous thermoplastic resins may be used alone or in combination of two or more. Among the amorphous thermoplastic resins, the cellulose resin is particularly preferably used because it is excellent in transparency, heat resistance and matching with liquid crystal, has a low intrinsic birefringence, and a small photoelastic coefficient.

The cellulose resin according to the present invention is a single or mixed acid ester containing at least one structure selected from a fatty acyl group and a substituted or unsubstituted aromatic acyl group. In the aromatic acyl group, when the aromatic ring is a benzene ring, examples of the substituent of the benzene ring include halogen atom, cyano, alkyl group, alkoxy group, aryl group, aryloxy group, acyl group, carbonamido group, sulfone. Amide group, ureido group, aralkyl group, nitro, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, carbamoyl group, sulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxy Sulfonyl group, aryloxysulfonyl group, alkylsulfonyloxy group and aryloxysulfonyl group, -S-R, -NH-CO-OR, -PH-R, -P (-R) ₂ , -PH-O-R, -P (-R) (-O-R), -P (- _{-R) 2, -PH (= O} ) -R-P (= O) (- R) 2, -PH (= O) -O-R, -P (= O) (- R) (- O- R), —P (═O) (— O—R) ₂ , —O—PH (═O) —R, —O—P (═O) (— R) ₂ —O—PH (═O) — O—R, —O—P (═O) (— R) (— O—R), —O—P (═O) (— O—R) ₂ , —NH—PH (═O) —R, -NH-P (= O) ( - R) (- O-R), - NH-P (= O) (- O-R) 2, -SiH 2 -R, -SiH (-R) 2, - Si (—R) ₃ , —O—SiH ₂ —R, —O—SiH (—R) _2, and —O—Si (—R) ₃ are included. R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably from 1 to 5, more preferably from 1 to 4, further preferably from 1 to 3, and preferably 1 or 2. Most preferred. As the substituent, a halogen atom, cyano, alkyl group, alkoxy group, aryl group, aryloxy group, acyl group, carbonamido group, sulfonamido group and ureido group are preferable, halogen atom, cyano, alkyl group, alkoxy group, An aryloxy group, an acyl group and a carbonamido group are more preferred, a halogen atom, cyano, an alkyl group, an alkoxy group and an aryloxy group are still more preferred, and a halogen atom, an alkyl group and an alkoxy group are most preferred.

  The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The alkyl group may have a cyclic structure or a branch. The number of carbon atoms in the alkyl group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and most preferably 1-4. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, hexyl, cyclohexyl, octyl and 2-ethylhexyl. The alkoxy group may have a cyclic structure or a branch. The number of carbon atoms in the alkoxy group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and most preferably 1-4. The alkoxy group may be further substituted with another alkoxy group. Examples of the alkoxy group include methoxy, ethoxy, 2-methoxyethoxy, 2-methoxy-2-ethoxyethoxy, butyloxy, hexyloxy and octyloxy.

  The number of carbon atoms in the aryl group is preferably 6-20, and more preferably 6-12. Examples of the aryl group include phenyl and naphthyl. The aryloxy group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the aryloxy group include phenoxy and naphthoxy. The number of carbon atoms in the acyl group is preferably 1-20, and more preferably 1-12. Examples of the acyl group include formyl, acetyl and benzoyl. The carbonamide group has preferably 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the carbonamido group include acetamide and benzamide. The number of carbon atoms in the sulfonamide group is preferably 1-20, and more preferably 1-12. Examples of the sulfonamide group include methanesulfonamide, benzenesulfonamide, and p-toluenesulfonamide. The ureido group has preferably 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of ureido groups include (unsubstituted) ureido.

  The number of carbon atoms in the aralkyl group is preferably 7-20, and more preferably 7-12. Examples of the aralkyl group include benzyl, phenethyl and naphthylmethyl. The number of carbon atoms of the alkoxycarbonyl group is preferably 1-20, and more preferably 2-12. Examples of the alkoxycarbonyl group include methoxycarbonyl. The aryloxycarbonyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 12 carbon atoms. Examples of the aryloxycarbonyl group include phenoxycarbonyl. The number of carbon atoms in the aralkyloxycarbonyl group is preferably 8-20, and more preferably 8-12. Examples of the aralkyloxycarbonyl group include benzyloxycarbonyl. The number of carbon atoms in the carbamoyl group is preferably 1-20, and more preferably 1-12. Examples of the carbamoyl group include (unsubstituted) carbamoyl and N-methylcarbamoyl. The number of carbon atoms in the sulfamoyl group is preferably 20 or less, and more preferably 12 or less. Examples of the sulfamoyl group include (unsubstituted) sulfamoyl and N-methylsulfamoyl. The number of carbon atoms of the acyloxy group is preferably 1-20, and more preferably 2-12. Examples of the acyloxy group include acetoxy and benzoyloxy.

  The number of carbon atoms of the alkenyl group is preferably 2-20, and more preferably 2-12. Examples of alkenyl groups include vinyl, allyl and isopropenyl. The alkynyl group preferably has 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of alkynyl groups include thienyl. The number of carbon atoms in the alkylsulfonyl group is preferably 1-20, and more preferably 1-12. The arylsulfonyl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. The alkyloxysulfonyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12. The number of carbon atoms of the alkylsulfonyloxy group is preferably 1-20, and more preferably 1-12. The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12.

  In the cellulose resin according to the present invention, when the hydrogen atom of the hydroxyl group of cellulose is a fatty acid ester with an aliphatic acyl group, the aliphatic acyl group has 2 to 20 carbon atoms, specifically acetyl, propionyl. , Butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, stearoyl and the like.

  In the present invention, the aliphatic acyl group is meant to include those further having a substituent, and the substituent is a substitution of a benzene ring when the aromatic ring is a benzene ring in the above-described aromatic acyl group. What was illustrated as a group is mentioned.

  Moreover, when the esterified substituent of the cellulose ester is an aromatic ring, the number of substituents X substituted on the aromatic ring is 0 or 1 to 5, preferably 1 to 3, and particularly preferable. Is one or two. Further, when the number of substituents substituted on the aromatic ring is 2 or more, they may be the same or different from each other, but they may be connected to each other to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline). , Isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.).

  The cellulose ester has a structure having a structure selected from at least one of a substituted or unsubstituted aliphatic acyl group and a substituted or unsubstituted aromatic acyl group in the cellulose ester. These may be used alone or as a mixed acid ester of cellulose, or two or more cellulose esters may be mixed and used.

  The cellulose resin according to the present invention is preferably at least one selected from cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose phthalate. .

  As the substitution degree of the mixed fatty acid ester, more preferred cellulose acetate propionate and lower fatty acid ester of cellulose acetate butyrate have an acyl group having 2 to 4 carbon atoms as a substituent, and the substitution degree of the acetyl group is X, When the substitution degree of propionyl group or butyryl group is Y, it is a cellulose resin containing a cellulose ester that simultaneously satisfies the following formulas (I) and (II).

Formula (I) 2.6 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 2.5
Of these, cellulose acetate propionate is particularly preferably used, among which 0.5 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 2.5. The part not substituted with the acyl group is usually present as a hydroxyl group. These can be synthesized by known methods.

  Furthermore, the cellulose resin used in the present invention is preferably one having a weight average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 8.5, particularly preferably 2.0 to 5.0, More preferably, it is 2.5-5.0, More preferably, 3.0-5.0 cellulose ester is used preferably.

An example of the cellulose resin used in the present invention is a mixed fatty acid cellulose ester having an aliphatic acyl group having 2 or more carbon atoms, and an average substitution degree of total acyl groups is 2.0 to 2.8, polymethacrylic acid The weight average molecular weight in terms of methyl is 10 × 10 ⁴ to 30 × 10 ⁴ . The weight average molecular weight can be measured by gel permeation chromatography (GPC) equipped with a refractive index detector. Regarding the substitution degree distribution of the acyl group, the average substitution degree of the acyl group at the 6-position of the glucose unit is about 0.50 to 0.85. The average substitution degree of the acetyl group is about 0.1 to 1.5. The acyl group can be composed of an acetyl group and at least one group selected from a propionyl group and a butyryl group. The ratio of the acetyl group to at least one group selected from a propionyl group and a butyryl group may be about the former / the latter = 2/98 to 60/40 (molar ratio). More specifically, in the cellulose ester, the average substitution degree of the total acyl group may be about 2.3 to 2.8, and includes an acetyl group and at least one group selected from a propionyl group and a butyryl group. May be about the former / the latter = 2/98 to 40/60 (molar ratio) depending on the type of acyl group, and the average degree of substitution of the acyl group at the 6-position of the glucose unit is 0. It may be about 70 to 0.85.

  The molecular weight of the cellulose ester can be selected within a range that does not impair the mechanical properties and moldability (including film formability), and the degree of dispersion (Mw / Mn) represented by the ratio of the weight average molecular weight Mw to the number average molecular weight Mn. ) Is about 2.5 to 8.0. In the measurement of molecular weight by gel permeation chromatography, the weight-based maximum molecular weight Mp and the number average molecular weight Mn are smaller than the weight average molecular weight Mw, and Mp / Mn> 2. Furthermore, in a cellulose ester (for example, a mixed fatty acid cellulose ester having two types of aliphatic acyl groups having 2 or more carbon atoms), the composition distribution half-value width measured by high performance liquid chromatography is 1.0 or less in terms of substitution degree ( For example, it may be 0.75 or less.

  Since such a cellulose ester has moderate birefringence and high stretchability, it is useful for preparing a film product having a wide range of retardation by forming into a film and stretching. The intrinsic birefringence Δn0 of the cellulose ester is about 0 to 0.08 (for example, 0.001 to 0.03).

  The following relationship is recognized among the refractive index n, the birefringence Δn, and the phase difference (in-plane retardation Re, thickness direction retardation Rth). Here, x represents the longitudinal direction (stretching direction in the case of uniaxial stretching) (x-axis), y represents the width direction (y-axis), z represents the thickness direction (z-axis), S represents the degree of orientation (0 to 1), Δn0 is intrinsic birefringence, and d is thickness.

Re = [nx − ((ny + nz) / 2)] · d≈Δn0 · S · d
Rth = [nz − ((nx + ny) / 2)] · d≈−1 / 2 · Δn0 · S · d
As is clear from the above relational expression, when the cellulose ester is used, the intrinsic birefringence is appropriate, so that the retardation (Re, Rth) can be accurately controlled by adjusting the orientation degree S by stretching. Even in the case of cellulose ester, if the intrinsic birefringence is small, a wide range of retardation (Re, Rth) cannot be covered, and if too large, the retardation (Re, Rth) changes sensitively depending on the degree of orientation S. Therefore, the retardation (Re, Rth) cannot be controlled accurately.

  The cellulose-based raw material cellulose used in the present invention may be wood pulp or cotton linter. The wood pulp may be softwood or hardwood, but softwood is more preferable. A cotton linter is preferably used from the viewpoint of peelability during film formation. The cellulose ester made from these can be mixed suitably or can be used independently.

  For example, the ratio of cellulose ester derived from cellulose linter: cellulose ester derived from wood pulp (coniferous): cellulose ester derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50: 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30.

  As other thermoplastic thermoplastic norbornene resins, for example, JP 2005-148568 A, as cyclic olefin resins, JP 2005-148568 A, as polycarbonate resins, for example, No. 41-12190, examples of styrene resins include JP-A-56-125703, examples of polyvinyl chloride resins include JP-B-45-34477, and examples of polyester resins include JP-A-11- Examples thereof include resins described in No. 227025.

  Among the compounds having a phenolic structure and a phosphite structure in the molecule used in the amorphous thermoplastic resin of the present invention, specific examples of compounds that are particularly preferably used are those represented by the general formula (I). Phosphites.

In the phosphites represented by the general formula (I) according to the present invention, the substituents R ¹ , R ² , R ⁴ , R ⁵ , R ⁷ , and R ⁸ are each independently a hydrogen atom and 1 to 8 carbon atoms. An alkyl group having 5 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group. R ¹ , R ² and R ⁴ are preferably an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, and an alkyl cycloalkyl group having 6 to 12 carbon atoms, and R ⁵ is a hydrogen atom, An alkyl group having 1 to 8 carbon atoms and a cycloalkyl group having 5 to 8 carbon atoms are preferable.

  Here, typical examples of the alkyl group having 1 to 8 carbon atoms include, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, t-pentyl. I-octyl, t-octyl, 2-ethylhexyl and the like. As typical examples of the cycloalkyl group having 5 to 8 carbon atoms, for example, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and the like are typical examples of the alkylcycloalkyl group having 6 to 12 carbon atoms. Examples include methylcyclopentyl, 1-methylcyclohexyl, 1-methyl-4-i-propylcyclohexyl and the like. Typical examples of the aralkyl group having 7 to 12 carbon atoms include benzyl, α-methylbenzyl, α, α-dimethylbenzyl and the like.

Among these, R ¹ and R ⁴ are preferably t-alkyl groups such as t-butyl, t-pentyl, and t-octyl, cyclohexyl, and 1-methylcyclohexyl. R ² is preferably an alkyl group having 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, t-pentyl, In particular, methyl, t-butyl, and t-pentyl are preferable. R ⁵ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, t-pentyl and the like. Is preferred.

R ³ and R ⁶ represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl groups as described above. A hydrogen atom or an alkyl group having 1 to 5 carbon atoms is preferable, and a hydrogen atom or a methyl group is particularly preferable.

  X represents a simple bond, a sulfur atom, or a methylene group which may be substituted with a C1-C8 alkyl or a C5-C8 cycloalkyl. Here, as a C1-C8 alkyl substituted by the methylene group and a C5-C8 cycloalkyl, the same alkyl group and cycloalkyl group as the above are mentioned, respectively. X is preferably a simple bond, a methylene group or a methylene group substituted by methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl or the like.

A represents an alkylene group having 2 to 8 carbon atoms or * —COR ¹⁰ — group (R ¹⁰ represents a simple bond or an alkylene group having 1 to 8 carbon atoms, and * represents bonding to the oxygen side). . Here, typical examples of the alkylene group having 2 to 8 carbon atoms include ethylene, propylene, butylene, pentamethylene, hexamethylene, octamethylene, 2,2-dimethyl-1,3-propylene, and the like. Propylene is preferably used. Also, * in the * -COR ¹⁰ -group indicates that carbonyl is bonded to phosphite oxygen. Typical examples of the alkylene group having 1 to 8 carbon atoms in R ¹⁰ include methylene, ethylene, propylene, butylene, pentamethylene, hexamethylene, octamethylene, 2,2-dimethyl-1,3-propylene and the like. Can be mentioned. R ¹⁰ is preferably a simple bond, ethylene or the like.

  One of Y and Z represents a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Here, as a C1-C8 alkyl group, the same alkyl group as the above is mentioned, for example, As a C1-C8 alkoxy group, an alkyl part is the said C1-C8, for example. The alkoxy group which is the same alkyl as an alkyl is mentioned. Moreover, as a C7-12 aralkyloxy group, the aralkyloxy group whose aralkyl part is the same aralkyl as the said C7-12 aralkyl is mentioned, for example.

  The phosphites represented by the general formula (I) are obtained by, for example, reacting bisphenols represented by the following general formula (II), phosphorus trihalides and hydroxy compounds represented by the following general formula (III). Can be manufactured.

In the formula, R ¹ , R ² , R ³ , X, R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , A, Y and Z have the same meaning as described above.

  Examples of the bisphenols (II) include 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,2 ′. -Methylenebis (4-n-propyl-6-t-butylphenol), 2,2'-methylenebis (4-i-propyl-6-t-butylphenol), 2,2'-methylenebis (4-n-butyl-6) -T-butylphenol), 2,2'-methylenebis (4-i-butyl-6-t-butylphenol), 2,2'-methylenebis (4,6-di-t-butylphenol), 2,2'-methylenebis (4-t-pentyl-6-t-butylphenol), 2,2'-methylenebis (4-nonyl-6-t-butylphenol), 2,2'-methylenebis (4- -Octyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-pentylphenol), 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,2 ' -Methylenebis [4-methyl-6- (α-methylcyclohexyl) phenol], 2,2'-methylenebis (4-methyl-6-nonylphenol), 2,2'-methylenebis (4-methyl-6-t-octylphenol) ), 2,2'-methylenebis (4,6-di-t-pentylphenol), 2,2'-methylenebis [4-nonyl-6- (α-methylbenzyl) phenol], 2,2'-methylenebis [ 4-nonyl-6- (α, α-dimethylbenzyl) phenol], 2,2′-ethylidenebis (4-methyl-6-butylphenol) It is.

  Representative examples of the hydroxy compound (III) when A is alkylene having 2 to 8 carbon atoms include, for example, 2- (3-t-butyl-4-hydroxyphenyl) ethanol, 2- (3-t-pentyl) -4-hydroxyphenyl) ethanol, 2- (3-t-octyl-4-hydroxyphenyl) ethanol, 2- (3-cyclohexyl-4-hydroxyphenyl) ethanol, 2- [3- (1-methylcyclohexyl)- 4-hydroxyphenyl] ethanol, 2- (3-tert-butyl-4-hydroxy-5-methylphenyl) ethanol, 2- (3-tert-pentyl-4-hydroxy-5-methylphenyl) ethanol, 2- ( 3-t-octyl-4-hydroxy-5-methylphenyl) ethanol, 2- (3-cyclohexyl-4-hydroxy-) -Methylphenyl) ethanol, 2- [3- (1-methylcyclohexyl) -4-hydroxy-5-methylphenyl] ethanol, 2- (3-t-butyl-4-hydroxy-5-ethylphenyl) ethanol, 2 -(3-t-pentyl-4-hydroxy-5-ethylphenyl) ethanol, 2- (3-t-octyl-4-hydroxy-5-ethylphenyl) ethanol, 2- (3-cyclohexyl-4-hydroxy- 5-ethylphenyl) ethanol, 2- [3- (1-methylcyclohexyl) -4-hydroxy-5-ethylphenyl] ethanol.

Representative examples of the hydroxy compound (III) when A is a * -COR ¹⁰ -group include, for example, 3-t-butyl-2-hydroxybenzoic acid, 3-t-butyl-4-hydroxybenzoic acid, 5 -T-butyl-2-hydroxybenzoic acid, 3-t-pentyl-4-hydroxybenzoic acid, 3-t-octyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3- (1- Methylcyclohexyl) -4-hydroxybenzoic acid, 3-t-butyl-2-hydroxy-5-methylbenzoic acid, 3-t-butyl-4-hydroxy-5-methylbenzoic acid, 5-t-butyl-2- Hydroxy-3-methylbenzoic acid, 3-t-pentyl-4-hydroxy-5-methylbenzoic acid, 3-t-octyl-4-hydroxy-5-methylbenzoic acid, 3-cyclo Hexyl-4-hydroxy-5-methylbenzoic acid, 3- (1-methylcyclohexyl) -4-hydroxy-5-methylbenzoic acid, 3-t-butyl-4-hydroxy-5-ethylbenzoic acid, 3-t -Pentyl-4-hydroxy-5-ethylbenzoic acid, 3-t-octyl-4-hydroxy-5-ethylbenzoic acid, 3-cyclohexyl-4-hydroxy-5-ethylbenzoic acid.

  Specific examples of such a compound represented by the general formula (I) are shown below.

Compound 1: 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetrakis-tert-butyldibenzo [d, f] [1.3 .2] Dioxaphosphin Compound 2: 6- [3- (3,5-Di-tert-butyl-4-hydroxyphenyl) propoxy] -2,4,8,10-tetrakis-tert-butyldibenzo [ d, f] [1.3.2] Dioxaphosphepine The amount of the compound represented by the general formula (I) to the amorphous thermoplastic resin is an amorphous thermoplastic resin per one compound to be added. It is 0.001-10.0 mass parts normally with respect to 100 mass parts, Preferably it is 0.01-5.0 mass parts, More preferably, it is 0.1-3.0 mass parts.

  The following effects can be obtained by adding the phosphites represented by the general formula (I) according to the present invention.

1) Due to the shear stress applied to the resin during the removal of foreign matter, a stable optical film can be produced without phase difference unevenness.
Since it is possible to suppress thermal decomposition of the resin due to heating, it is possible to suppress thermal decomposition of the resin due to temperature rise caused by the shear stress applied to the resin during the removal of foreign matter, and there is no phase difference unevenness, and a stable optical film Can be manufactured, and production efficiency can be improved.

  2) Since the decomposition of the molten resin after passing through the filter is further suppressed, the mixing of foreign matters into the product is reduced, and a higher quality film can be provided.

  3) Since the decomposition of the molten resin up to the filter can be suppressed, the frequency of replacement of the filter is reduced, which can contribute to productivity improvement.

  4) Since the allowable range with respect to the shear stress of the molten resin is widened, versatility is increased, and it is possible to expand the types of resins that can be used.

  5) The melting temperature range of the molten resin can be widened, production in a lower viscosity region is possible, the flow rate is increased, and it is possible to contribute to productivity improvement.

  In addition to this, when the amorphous thermoplastic resin is melted by the melt extruder shown in FIG. 2, in addition to the phosphites represented by the general formula (I), a phenol-based stabilizer and a hindered amine-based stabilizer At least one selected from among agents, phosphorus stabilizers, and sulfur stabilizers, or two or more stabilizers may be added. By appropriately selecting these stabilizers and adding them to an amorphous thermoplastic resin in combination with a phosphite ester, an amorphous thermoplastic resin film having excellent optical characteristics, particularly retardation in the width direction (retardation) An excellent optical film can be obtained with a low coefficient of variation (CV).

  As a preferable phenol-based stabilizer, conventionally known ones can be used, for example, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2 , 4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate and the like, and JP-A Nos. 63-179953 and 1-168643. Acrylate compounds described in Japanese Patent Publication No. 1; octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis (4-methyl-6-tert-butylphenol) ), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenylpropionate) methane), ie pentaerythrmethyl -Tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenylpropionate)), triethylene glycol-bis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate ) And the like; 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1,3,5-triazine, 4-bisoctylthio-1 , 3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3,5-triazi Triazine group-containing phenol compounds, such as and the like.

  Preferred hindered amine stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (1 , 2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-benzyloxy-2,2) , 6,6-tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6- Pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1-acryloyl-2,2,6,6) Tetramethyl-4-piperidyl) 2,2-bis (3,5-di-tert-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6-pentamethyl-4 -Piperidyl) decanedioate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -1- [2- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy) ethyl] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- (2,2 , 6,6-tetramethyl-4-piperidyl) amino-N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide, tetrakis (2,2,6,6-tetramethyl-4- Piperidi ) 1,2,3,4-butane tetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, and the like.

  The phosphorus stabilizer is not particularly limited as long as it is usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl). ) Phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9, Monophosphite compounds such as 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecylphos Phyto), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C15) phos Aito) and the like diphosphite compounds such as. Among these, monophosphite compounds are preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.

  More preferred sulfur stabilizers include, for example, dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3-thio Dipropionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, etc. Is mentioned. These stabilizers can be used singly or in combination of two or more with respect to the phosphites, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention. It is 0.01-5 mass parts normally with respect to 100 mass parts of cellulose esters, Preferably it is 0.03-3 mass parts.

(Additive)
The amorphous thermoplastic resin according to the present invention includes, as additives, at least an ester plasticizer comprising a polyhydric alcohol and a monovalent carboxylic acid, and an ester plasticizer comprising a polyvalent carboxylic acid and a monohydric alcohol. Contains one plasticizer, in addition to peroxide decomposers, radical scavengers, metal deactivators, UV absorbers, matting agents, dyes, pigments, and other plasticizers. It doesn't matter.

  It is represented by coloring and molecular weight reduction, including decomposition reactions that have not been elucidated, such as oxidation prevention of film constituent materials, capture of acid generated by decomposition, suppression or prohibition of decomposition reaction due to radical species due to light or heat, etc. Additives are used in order to suppress the generation of volatile components due to deterioration and material decomposition, and to impart functions such as moisture permeability and slipperiness.

  On the other hand, when the film constituent material is heated and melted, the decomposition reaction becomes remarkable, and this decomposition reaction may be accompanied by strength deterioration of the constituent material due to coloring or molecular weight reduction. Further, undesirable volatile components may be generated due to the decomposition reaction of the film constituting material.

  When the film constituent material is heated and melted, the presence of the above-mentioned additives is excellent in terms of suppressing the deterioration of the strength based on the deterioration and decomposition of the material, or maintaining the inherent strength of the material. From the viewpoint of producing a more stable optical film, it is necessary that the above-mentioned additives be present.

  In addition, the presence of the above-mentioned additives suppresses the formation of colored substances in the visible light region at the time of heating and melting, or is not preferable as an optical film such as transmittance and haze value caused by mixing volatile components in the film. Is excellent in that it can be suppressed or eliminated.

  When the optical film produced by the method for producing an optical film of the present invention is used in a liquid crystal display device, since the haze value is affected when it exceeds 1%, the haze value is preferably less than 1%, more preferably It is less than 0.5%.

  In the above-described film constituent material storage or film forming process, deterioration reactions due to oxygen in the air may occur simultaneously. In this case, the effect of reducing the oxygen concentration in the air can be used together with the stabilizing action of the additive in realizing the present invention. This includes the use of nitrogen or argon as an inert gas as a known technique, degassing operation under reduced pressure to vacuum, and operation under a sealed environment, and at least one of these three methods includes the above additives. It can be used in combination with the method. By reducing the probability that the film constituent material comes into contact with oxygen in the air, deterioration of the material can be suppressed, which is preferable for the purpose of the present invention.

  Since the optical film produced by the method for producing an optical film of the present invention is used as a polarizing plate protective film, it is also a film constituent material from the viewpoint of improving the storage stability with time with respect to the polarizing plate and the polarizer constituting the polarizing plate. It is preferred that the above-mentioned additives are present therein.

  In the liquid crystal display device using the polarizing plate using the optical film produced by the method for producing an optical film of the present invention, the above-mentioned additives are present in the optical film produced by the method for producing an optical film of the present invention. Therefore, from the viewpoint of suppressing the above-mentioned alteration and deterioration, the optical film can be stored over time, and the optical compensation design provided with the optical film can function for a long time in improving the display quality of the liquid crystal display device. Excellent in terms of expression.

(Ester plasticizer consisting of polyhydric alcohol and monovalent carboxylic acid, ester plasticizer consisting of polyvalent carboxylic acid and monovalent alcohol)
In general, it is preferable to add a compound known as a plasticizer from the viewpoint of film modification such as improvement of mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability. Further, in the melt extrusion method carried out in the present invention, the amorphous material is used at the same heating temperature for the purpose of lowering the melting temperature of the film constituting material by adding a plasticizer, rather than the glass transition temperature of the amorphous thermoplastic resin used alone. This includes the purpose of reducing the viscosity of the film constituting material containing the plasticizer rather than the thermoplastic resin. Here, in the present invention, the melting temperature of the film constituent material means a temperature at which the material is heated in a state where the material is heated and fluidity is developed.

  When the amorphous thermoplastic resin is used alone, the fluidity for forming a film is not exhibited when the temperature is lower than the glass transition temperature. However, an amorphous thermoplastic resin exhibits a fluidity due to a decrease in elastic modulus or viscosity due to the absorption of heat at a glass transition temperature or higher. In order to melt the film constituent material, it is preferable for the plasticizer to be added to have a melting point or glass transition temperature lower than the glass transition temperature of the amorphous thermoplastic resin in order to satisfy the above object. Furthermore, an ester plasticizer composed of a polyhydric alcohol and a monovalent carboxylic acid, and an ester plasticizer composed of a polyvalent carboxylic acid and a monovalent alcohol have a high affinity with the amorphous thermoplastic resin, and are more preferable.

  An ethylene glycol ester plasticizer that is one of polyhydric alcohol esters: Specifically, ethylene glycol alkyl ester plasticizers such as ethylene glycol diacetate and ethylene glycol dibutyrate, ethylene glycol dicyclopropylcarboxylate And ethylene glycol cycloalkyl ester plasticizers such as ethylene glycol dicyclohexylcarboxylate, and ethylene glycol aryl ester plasticizers such as ethylene glycol dibenzoate and ethylene glycol di4-methylbenzoate. These alkylate groups, cycloalkylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mix of alkylate group, cycloalkylate group and arylate group, and these substituents may be bonded by a covalent bond. Further, the ethylene glycol part may be substituted, the ethylene glycol ester partial structure may be part of the polymer or regularly pendant, and may be an antioxidant, an acid scavenger, an ultraviolet absorber, etc. It may be introduced into a part of the molecular structure of the additive.

  Glycerin ester plasticizer that is one of polyhydric alcohol esters: Specifically, glycerol alkyl esters such as triacetin, tributyrin, glycerol diacetate caprylate, glycerol oleate propionate, glycerol tricyclopropylcarboxylate, glycerol Glycerin cycloalkyl esters such as tricyclohexylcarboxylate, glycerol aryl esters such as glycerol tribenzoate and glycerol 4-methylbenzoate, diglycerol tetraacetylate, diglycerol tetrapropionate, diglycerol acetate tricaprylate, diglycerol tetralaur Diglycerin alkyl ester such as rate, diglycerin tetracyclobutylcarboxylate, diglycerin tetracyclo Diglycerol cycloalkyl esters such as emissions chill carboxylate, diglycerin tetrabenzoate, diglycerin aryl ester such as diglycerin 3-methylbenzoate or the like. These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mixture of alkylate group, cycloalkylcarboxylate group, and arylate group, and these substituents may be bonded by a covalent bond. Furthermore, the glycerin and diglycerin part may be substituted, the partial structure of the glycerin ester and the diglycerin ester may be part of the polymer, or may be regularly pendant, and the antioxidant, acid scavenger, You may introduce | transduce into a part of molecular structure of additives, such as a ultraviolet absorber.

  Specific examples of other polyhydric alcohol ester plasticizers include polyhydric alcohol ester plasticizers described in paragraphs 30 to 33 of JP-A No. 2003-12823.

  These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Further, it may be a mixture of alkylate group, cycloalkylcarboxylate group, and arylate group, and these substituents may be bonded by a covalent bond. Furthermore, the polyhydric alcohol part may be substituted, and the partial structure of the polyhydric alcohol may be part of the polymer or regularly pendant, and may be an antioxidant, an acid scavenger, an ultraviolet absorber. May be introduced into a part of the molecular structure of the additive.

  Among the ester plasticizers composed of the polyhydric alcohol and the monovalent carboxylic acid, alkyl polyhydric alcohol aryl esters are preferable. Specifically, the above-mentioned ethylene glycol dibenzoate, glycerin tribenzoate, diglycerin tetrabenzoate, Exemplified compound 16 described in paragraph 32 of Kokai 2003-12823 can be mentioned.

  Dicarboxylic acid ester plasticizer that is one of polyvalent carboxylic acid esters: Specifically, alkyl dicarboxylate alkyl such as didodecyl malonate (C1), dioctyl adipate (C4), dibutyl sebacate (C8), etc. Ester plasticizers, alkyl dicarboxylic acid cycloalkyl ester plasticizers such as dicyclopentyl succinate and dicyclohexyl adipate, alkyl dicarboxylic acid aryl ester plasticizers such as diphenyl succinate and di4-methylphenyl glutarate, Cycloalkyl dicarboxylic acid alkyl ester plasticizers such as dihexyl-1,4-cyclohexanedicarboxylate and didecylbicyclo [2.2.1] heptane-2,3-dicarboxylate, dicyclohexyl-1,2-cyclobutane Dicarbo Cycloalkyl dicarboxylic acid cycloalkyl ester plasticizers such as sylate and dicyclopropyl-1,2-cyclohexyl dicarboxylate, diphenyl-1,1-cyclopropyl dicarboxylate, di2-naphthyl-1,4-cyclohexane Cycloalkyldicarboxylic acid aryl ester plasticizers such as dicarboxylate, aryl dicarboxylic acid alkyl ester plasticizers such as diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dicyclopropyl phthalate Aryl dicarboxylic acid cycloalkyl ester plasticizers such as dicyclohexyl phthalate, and aryl dicarboxylic acid aryl esters such as diphenyl phthalate and di 4-methylphenyl phthalate. Ether-based plasticizers. These alkoxy groups and cycloalkoxy groups may be the same or different, may be mono-substituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, or these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. Also, the partial structure of phthalate ester may be part of the polymer or regularly pendant to the polymer, and part of the molecular structure of additives such as antioxidants, acid scavengers, UV absorbers, etc. It may be introduced.

  Examples of other polycarboxylic acid ester plasticizers include alkyl polycarboxylic acid alkyl esters such as tridodecyl tricarbarate and tributyl-meso-butane-1,2,3,4-tetracarboxylate. Plasticizers, alkylpolycarboxylic acid cycloalkyl ester plasticizers such as tricyclohexyltricarbarate, tricyclopropyl-2-hydroxy-1,2,3-propanetricarboxylate, triphenyl 2-hydroxy- Alkyl polyvalent carboxylic acid aryl ester plasticizers such as 1,2,3-propanetricarboxylate, tetra-3-methylphenyltetrahydrofuran-2,3,4,5-tetracarboxylate, tetrahexyl-1,2, 3,4-cyclobutanetetracarboxylate, tetrabu Cycloalkyl polycarboxylic acid alkyl ester plasticizers such as ru-1,2,3,4-cyclopentanetetracarboxylate, tetracyclopropyl-1,2,3,4-cyclobutanetetracarboxylate, tricyclohexyl- Cycloalkyl polycarboxylic acid cycloalkyl ester plasticizers such as 1,3,5-cyclohexyl tricarboxylate, triphenyl-1,3,5-cyclohexyl tricarboxylate, hexa-4-methylphenyl-1,2, Cycloalkyl polycarboxylic acid aryl ester plasticizers such as 3,4,5,6-cyclohexylhexacarboxylate, tridodecylbenzene-1,2,4-tricarboxylate, tetraoctylbenzene-1,2,4 , 5-tetracarboxylate and other aryl polyvalent Rubinoic acid alkyl ester plasticizers, tricyclopentylbenzene-1,3,5-tricarboxylate, tetracyclohexylbenzene-1,2,3,5-tetracarboxylate and other aryl polyvalent carboxylic acid cycloalkyl esters Plasticizers of aryl polyvalent carboxylic acid aryl esters such as triphenylbenzene-1,3,5-tetracartoxylate and hexa-4-methylphenylbenzene-1,2,3,4,5,6-hexacarboxylate A plasticizer is mentioned. These alkoxy groups and cycloalkoxy groups may be the same or different, and may be mono-substituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, or these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. The partial structure of phthalate ester may be part of the polymer, or may be regularly pendant to the polymer, and introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. May be.

  Among the ester plasticizers composed of the polyvalent carboxylic acid and the monohydric alcohol, dialkyl carboxylic acid alkyl esters are preferable, and specific examples include the dioctyl adipate and tridecyl tricarbalate.

(Other plasticizers)
Examples of other plasticizers used in the present invention include phosphate ester plasticizers and polymer plasticizers.

  Phosphate ester plasticizers: specifically, phosphoric acid alkyl esters such as triacetyl phosphate and tributyl phosphate, phosphoric acid cycloalkyl esters such as tricyclobenthyl phosphate and cyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate And phosphoric acid aryl esters such as cresyl phenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, trinaphthyl phosphate, trixylyl phosphate, tris ortho-biphenyl phosphate. These substituents may be the same or different, and may be further substituted. Further, it may be a mix of an alkyl group, a cycloalkyl group, and an aryl group, or the substituents may be covalently bonded.

  Also, alkylene bis (dialkyl phosphate) such as ethylene bis (dimethyl phosphate), butylene bis (diethyl phosphate), alkylene bis (diaryl phosphate) such as ethylene bis (diphenyl phosphate), propylene bis (dinaphthyl phosphate), phenylene bis (dibutyl phosphate) ), Arylene bis (dialkyl phosphate) such as biphenylene bis (dioctyl phosphate), phosphate esters such as arylene bis (diaryl phosphate) such as phenylene bis (diphenyl phosphate) and naphthylene bis (ditoluyl phosphate). These substituents may be the same or different, and may be further substituted. Further, it may be a mix of an alkyl group, a cycloalkyl group, and an aryl group, or the substituents may be covalently bonded.

  Furthermore, the partial structure of the phosphate ester may be part of the polymer, or may be regularly pendant, or introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. May be. Among the above-mentioned compounds, phosphoric acid aryl ester and arylene bis (diaryl phosphate) are preferable, and specifically, triphenyl phosphate and phenylene bis (diphenyl phosphate) are preferable.

  Polymer plasticizer: Specifically, aliphatic hydrocarbon polymer, alicyclic hydrocarbon polymer, acrylic polymer such as polyethyl acrylate and polymethyl methacrylate, polyvinyl isobutyl ether, poly N-vinyl pyrrolidone, etc. Examples include vinyl polymers, styrene polymers such as polystyrene and poly 4-hydroxystyrene, polybutylene succinates, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyethers such as polyethylene oxide and polypropylene oxide, polyamides, polyurethanes, and polyureas. It is done. The number average molecular weight is preferably about 1,000 to 500,000, particularly preferably 5,000 to 200,000. If it is 1,000 or less, a problem occurs in volatility, and if it exceeds 500,000, the plasticizing ability is lowered, and the mechanical properties of the cellulose ester film are adversely affected. These polymer plasticizers may be a homopolymer composed of one type of repeating unit or a copolymer having a plurality of repeating structures. Two or more of the above polymers may be used in combination.

(Acid scavenger)
The acid scavenger is an agent that plays a role of trapping an acid (protonic acid) remaining in the amorphous thermoplastic resin brought in from the production. Further, when the amorphous thermoplastic resin is melted, side chain hydrolysis is accelerated by moisture and heat in the polymer, and acetic acid and propionic acid are generated in the case of CAP. A compound having an epoxy structure, a tertiary amine, an ether structure, or the like may be used as long as it can be chemically bonded to an acid, but is not limited thereto.

  Specifically, it is preferable to comprise an epoxy compound as an acid scavenger described in US Pat. No. 4,137,201. Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of diglycidyl ethers of various polyglycols, particularly about 8 to 40 moles of ethylene oxide per mole of polyglycol. Metal glycol compounds such as polyglycols, diglycidyl ethers of glycerol (eg, those conventionally used in and together with vinyl chloride polymer compositions), epoxidized ether condensation products, bisphenol A Diglycidyl ether (ie, 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester (especially an ester of alkyl of about 2 to 2 carbon atoms of a fatty acid of 2 to 22 carbon atoms such as butyl Epoxy stearate) ), And various epoxidized long chain fatty acid triglycerides and the like (eg, epoxidized vegetable oils and other unsaturated natural oils, sometimes represented by and exemplified by compositions such as epoxidized soybean oil, these are sometimes epoxidized natural glycerides) Or unsaturated fatty acids, which generally contain 12 to 22 carbon atoms)). Particularly preferred are commercially available epoxy group-containing epoxide resin compounds EPON 815c and other epoxidized ether oligomer condensation products of general formula (1).

  In the above formula, n is equal to 0-12. Further possible acid scavengers that can be used include those described in paragraphs 87 to 105 of JP-A-5-194788.

(UV absorber)
As an ultraviolet absorber, from the viewpoint of preventing deterioration of a polarizer or a display device with respect to ultraviolet rays, the ultraviolet absorber has an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display properties, absorption of visible light having a wavelength of 400 nm or more is absorbed. Less is preferred. Examples include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, etc., but benzophenone compounds and less colored benzotriazole compounds preferable. Moreover, you may use the ultraviolet absorber of Unexamined-Japanese-Patent No. 10-182621, 8-337574, and the polymeric ultraviolet absorber of Unexamined-Japanese-Patent No. 6-148430.

  Specific examples of useful benzotriazole ultraviolet absorbers include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl). ) Benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2-methylenebis ( 4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydro Cis-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy Examples include, but are not limited to, a mixture of -5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate.

  As commercially available products, TINUVIN 109, TINUVIN 171 and TINUVIN 360 (all manufactured by Ciba Specialty Chemicals) can also be used.

  Specific examples of benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy- 5-benzoylphenylmethane) and the like, but are not limited thereto.

  In the present invention, the ultraviolet absorber is preferably added in an amount of 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and further preferably 1 to 5% by mass. Two or more of these may be used in combination.

(Matting agent)
To the non-crystalline thermoplastic resin according to the present invention, fine particles such as a matting agent can be added in order to impart slipperiness, and examples of the fine particles include fine particles of an inorganic compound or fine particles of an organic compound. The matting agent is preferably as fine as possible. Examples of the fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, and aluminum silicate. And inorganic fine particles such as magnesium silicate and calcium phosphate and crosslinked polymer fine particles. Among these, silicon dioxide is preferable because it can reduce the haze of the film. In many cases, fine particles such as silicon dioxide are surface-treated with an organic material, but such a material is preferable because it can reduce the haze of the film.

  Preferred organic substances for the surface treatment include halosilanes, alkoxysilanes, silazane, siloxane and the like. The larger the average particle size of the fine particles, the greater the sliding effect, and the smaller the average particle size, the better the transparency. The average particle size of the secondary particles of the fine particles is in the range of 0.05 to 1.0 μm. The average particle size of secondary particles of the fine particles is preferably 5 to 50 nm, more preferably 7 to 14 nm. These fine particles are preferably used in an amorphous thermoplastic resin film in order to produce an unevenness of 0.01 to 1.0 μm on the surface of the amorphous thermoplastic resin film. The content of the fine particles in the amorphous thermoplastic resin is preferably 0.005 to 0.3% by mass with respect to the amorphous thermoplastic resin.

  Examples of the fine particles of silicon dioxide include Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600 manufactured by Nippon Aerosil Co., Ltd., preferably Aerosil 200V, R972. , R972V, R974, R202, R812. Two or more kinds of these fine particles may be used in combination. When using 2 or more types together, it can mix and use in arbitrary ratios. In this case, fine particles having different average particle sizes and materials, for example, Aerosil 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9: 0.1.

  The presence of fine particles in the amorphous thermoplastic resin film used as the matting agent can be used for another purpose to improve the strength of the amorphous thermoplastic resin film. In addition, the presence of the fine particles in the amorphous thermoplastic resin film can improve the orientation of the amorphous thermoplastic resin itself constituting the optical film of the present invention.

(Retardation control agent)
In the optical film of the present invention, an alignment film is formed to provide a liquid crystal layer, and the optical film and the retardation derived from the liquid crystal layer are combined to provide an optical compensation capability. Polarizing plate processing may be performed. The compound to be added to adjust the retardation is an aromatic compound having two or more aromatic rings as described in EP 911,656A2, which is used as a retardation control agent. You can also. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. An aromatic heterocyclic ring is particularly preferred, and the aromatic heterocyclic ring is generally an unsaturated heterocyclic ring. Of these, a 1,3,5-triazine ring is particularly preferred.

(Polymer material)
The optical film according to the present invention may be appropriately selected from polymer materials and oligomers other than the amorphous thermoplastic resin and mixed. The above-mentioned polymer materials and oligomers are preferably those having excellent compatibility with the amorphous thermoplastic resin, and the transmittance when formed into a film is 80% or more, more preferably 90% or more, more preferably 92% or more. It is preferable. The purpose of mixing at least one of polymer materials and oligomers other than the amorphous thermoplastic resin includes meanings for viscosity control during heating and melting and for improving film physical properties after film processing. In this case, it can be included as the above-mentioned other additives.

(Functional layer)
When producing an optical film by the method for producing an optical film of the present invention, before and / or after stretching, an antistatic layer, a hard coat layer, an antireflection layer, a slippery layer, an easy adhesion layer, an antiglare layer. Functional layers such as a barrier layer and an optical compensation layer may be provided. In particular, it is preferable to provide at least one layer selected from an antistatic layer, a hard coat layer, an antireflection layer, an easy adhesion layer, an antiglare layer, and an optical compensation layer. At this time, various surface treatments such as corona discharge treatment, plasma treatment, and chemical treatment can be performed as necessary.

  In the film forming process, the clip gripping portions at both ends of the cut film are pulverized or granulated as necessary, and then used as the same type of film raw material or as a different type of film raw material. It may be reused.

  It is also possible to produce an amorphous thermoplastic resin film having a laminated structure by co-extrusion of a composition containing amorphous thermoplastic resins having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent. . For example, an amorphous thermoplastic resin film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. More plasticizers and UV absorbers can be added to the core layer than the skin layer, and may be added only to the core layer. It is also possible to change the type of plasticizer and ultraviolet absorber between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer. Also, the viscosity of the melt containing the cellulose ester during melt casting may be different between the skin layer and the core layer, and the viscosity of the skin layer> the viscosity of the core layer or the viscosity of the core layer ≧ the viscosity of the skin layer.

  The optical film manufactured by the method for manufacturing an optical film of the present invention can be used for a polarizing plate protective film. When using as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. The obtained optical film is treated with alkali, and a polyvinyl alcohol film is immersed and stretched in an iodine solution, and a polarizer protective film is attached to both sides of the polarizer using a completely saponified polyvinyl alcohol aqueous solution on both sides of the polarizer. There is a method of combining, and at least one side is preferable from the viewpoint that the optical film which is the polarizing plate protective film of the present invention can be directly bonded to the polarizer.

  Further, instead of the alkali treatment, an easy adhesion process described in JP-A-6-94915 and JP-A-6-118232 may be performed to perform polarizing plate processing.

  The polarizing plate is composed of a polarizer and a protective film for protecting both surfaces of the polarizer, and can further be constructed by laminating a protective film on one surface of the polarizing plate and a separate film on the opposite surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the adhesive layer bonded to a liquid crystal plate, and is used on the surface side which bonds a polarizing plate to a liquid crystal cell.

(Dimensional stability)
The optical film manufactured by the method for manufacturing an optical film of the present invention has a dimension stability at 80 ° C. and 90% RH when the dimensional stability is based on the size of the film left at 23 ° C. and 55% RH for 24 hours. The variation value is preferably less than ± 1.0%, more preferably less than 0.5%, and particularly preferably less than 0.1%.

  In order to use the optical film produced by the method for producing an optical film of the present invention as a protective film for a polarizing plate, if the optical film itself has a fluctuation beyond the above range, Since the absolute value and the orientation angle deviate from the initial settings, the display quality improvement ability may be reduced or the display quality may be deteriorated.

(Film constituent materials)
Presence of additives in film constituent materials includes amorphous thermoplastic resins, plasticizers, antioxidants, and other UV-absorbing agents, matting agents, retardation control agents, etc. Is superior in terms of suppressing or preventing the generation of volatile components due to alteration or decomposition. Further, the additive itself is required not to generate a volatile component in the melting temperature region of the film constituting material.

  The content of the volatile component when the film constituent material is melted is 1% by mass or less, preferably 0.5% by mass or less, preferably 0.2% by mass or less, more preferably 0.1% by mass or less. It is desirable to be. In the present invention, a heat loss from 30 ° C. to 350 ° C. is determined using a differential thermogravimetric measuring device (TG / DTA200 manufactured by Seiko Denshi Kogyo Co., Ltd.), and the amount is defined as the content of volatile components.

(Stretching operation, refractive index control)
The optical film produced by the method for producing an optical film of the present invention can be controlled in refractive index by a stretching operation. As the stretching operation, refraction in a preferable range by stretching 1.0 to 2.0 times in one direction of the amorphous thermoplastic resin film and 1.01 to 2.5 times in the direction orthogonal to the film plane. The rate can be controlled.

  For example, the film can be stretched sequentially or simultaneously in the longitudinal direction of the film and the direction perpendicular to the longitudinal direction of the film, that is, the width direction. At this time, if the stretching ratio in at least one direction is too small, a sufficient phase difference cannot be obtained, and if it is too large, stretching may become difficult and breakage may occur.

  For example, when the formed film is stretched in the conveyance direction, if the shrinkage in the width direction is too large, the refractive index in the thickness direction of the film becomes too large. In this case, the width shrinkage of the film can be suppressed or improved by stretching in the width direction. When stretching in the width direction, the refractive index may be distributed with a width. This may be seen when using the tenter method, but it is a phenomenon that occurs when the film is stretched in the width direction and contraction force is generated at the center of the film and the end is fixed, or the bowing phenomenon. It is thought to be called. Even in this case, the bowing phenomenon can be suppressed by stretching in the casting direction, and the width difference distribution can be improved less.

  Furthermore, the film thickness fluctuation | variation of the film obtained can be reduced by extending | stretching in the biaxial direction orthogonal to each other. When the film thickness variation of the optical film is too large, the phase difference becomes uneven, and unevenness such as coloring may be a problem when used in a liquid crystal display.

  The film thickness variation of the amorphous thermoplastic resin film support is preferably in the range of ± 3%, more preferably ± 1%. For the purposes as described above, the method of stretching in the biaxial directions perpendicular to each other is effective, and the stretching ratio in the biaxial directions perpendicular to each other is finally 1.0 to 2.0 times in the casting direction. The width direction is preferably 1.01 to 2.5 times, the casting direction is 1.01 to 1.5 times, and the width direction is 1.05 to 2.0 times. preferable.

  When an amorphous thermoplastic resin that obtains positive birefringence with respect to stress is used, the slow axis of the optical film can be provided in the width direction by stretching in the width direction. In this case, in order to improve display quality, the slow axis of the optical film is preferably in the width direction, and it is necessary to satisfy (stretch ratio in the width direction)> (stretch ratio in the casting direction). is there.

  There is no particular limitation on the method of stretching the web. For example, a method of adding a circumferential speed difference to a plurality of rolls and using the difference in the circumferential speed of the rolls to stretch in the vertical direction, fixing both ends of the web with clips and pins, and widening the gap between the clips and pins in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination. Alternatively, in the case of the tenter method, it is preferable to drive the clip portion by the linear drive method 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 step by a tenter, and it may be a pin tenter or a clip tenter.

  When the optical film manufactured by the method for manufacturing an optical film of the present invention is a polarizing plate protective film, the thickness of the protective film is preferably 10 to 500 μm. In particular, it is preferably 20 μm or more, and more preferably 35 μm or more. Further, it is preferably 150 μm or less, more preferably 120 μm or less. Most preferably, it is 25 or more and 90 micrometers. If the optical film is thicker than the above region, the polarizing plate after the polarizing plate processing becomes too thick, and is not suitable for a thin and lightweight purpose in a liquid crystal display used for a notebook personal computer or a mobile electronic device. On the other hand, if it is thinner than the above region, it is not preferable because retardation is difficult to develop, and the film has high moisture permeability and the ability to protect the polarizer from humidity is reduced.

  The slow axis or the fast axis of the optical film produced by the method for producing an optical film of the present invention exists in the film plane, and θ1 is −1 ° or more and +1 when the angle formed with the film forming direction is θ1. It is preferably at most 0 °, more preferably from −0.5 ° to + 0.5 °. 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.

(Liquid crystal display device)
In a liquid crystal display device, a substrate containing liquid crystal is usually arranged between two polarizing plates, but a polarizing plate protective film to which an optical film produced by the method for producing an optical film of the present invention is applied is placed in any part. Even so, excellent display properties can be obtained. In particular, since a clear hard coat layer, an antiglare layer, an antireflection layer, and the like are provided on the polarizing plate protective film on the display side outermost surface of the liquid crystal display device, it is particularly preferable to use the polarizing plate protective film for this portion.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the aspect of this invention is not limited to this. In addition, the following "part" represents a "mass part".

Example 1
(Manufacture of cellulose ester film)
Cellulose acetate propionate CAP482-20 (manufactured by Eastman Chemical Co., Ltd.) as a cellulose ester was dried in air at 130 ° C. for 2 hours and allowed to cool to room temperature. After that, using the manufacturing apparatus shown in FIG. 2, it is heated and melted at a melting temperature of 220 ° C., and as shown in Table 1, the nominal filtration accuracy of the filter of the melt extruder and the value of the shear stress during filtration are changed. After melt extrusion molding from a T-die and molding 10 m of unstretched cellulose ester, the film was further stretched at a stretch ratio of 1.1 × 1.2 at 150 ° C. to form a cellulose acetate propionate film having a thickness of 80 μm. Sample No. 101-125.

  In addition, 5.0 mass parts of plasticizer ethylene glycol dicyclopropylcarboxylate was added to cellulose acetate propionate and melted.

The filter used was a leaf disc filter (Fine pore manufactured by Nippon Seisen Co., Ltd., using a filtration area of 20 m ² ). The shear stress was changed by changing the filtration pressure, the nominal filtration accuracy of the filter, and the thickness of the filter because the shear stress can be obtained by the following equation.

Shear stress = (filtration pressure × filter nominal filtration accuracy) / (filter thickness)
Filtration pressure correlates with resin viscosity, flow rate, filtration area, filter nominal filtration accuracy, filter thickness, so filtration pressure can be changed by changing resin viscosity, flow rate, filter nominal filtration accuracy, filter thickness. The filtration pressure was measured with a pressure sensor installed in the filtration device. The resin viscosity was measured with a flow tester CFT-500 manufactured by Shimadzu Corporation by changing the resin temperature and changing the additive type and amount. The flow rate was controlled by a gear pump installed on the upstream side of the filter. The nominal filtration accuracy of the filter was measured by the bubble point method (ASTM F316-86, JIS K3832). The thickness of the filter was measured using a caliper.

Evaluation Each sample No. Table 1 shows the results of evaluations according to the evaluation ranks shown below, which are attached to 101 to 125, tested for the retardation coefficient of variation (CV), haze, and bright spot foreign matter and tested as follows.

Retardation coefficient of variation (CV)
Retardation is measured at intervals of 1 cm in the width direction of the molded sample, and is represented by a retardation variation coefficient (CV) obtained from the following formula. For measurement, an automatic birefringence meter KOBURA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) is used and is three-dimensionally spaced at 1 cm intervals in the width direction of the sample at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH. The birefringence was measured and the measured value was substituted into the following equation.

Thickness direction retardation Rt = ((nx + ny) / 2−nz) × d
Here, d is the thickness (nm) of the film, the refractive index nx (also referred to as the maximum refractive index in the plane of the film, the refractive index in the slow axis direction), ny (in the direction perpendicular to the slow axis in the film plane). ) (Refractive index of the film in the thickness direction). The standard deviation by the (n-1) method was calculated | required for the obtained in-plane and thickness direction retardation, respectively. For the retardation distribution, the coefficient of variation (CV) shown below was obtained and used as an index. In actual measurement, n was set to 100.

Coefficient of variation (CV) = standard deviation / retardation average value Evaluation rank of retardation ◎: Retardation coefficient of variation (CV) is less than 1.5% ○: Retardation coefficient of variation (CV) is 1.5% or more Less than 5% Δ: Retardation coefficient of variation (CV) is 5% or more and less than 10% X: Retardation coefficient of variation (CV) is 10% or more Haze haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.) ) Was used for conversion to a haze value when the sample thickness was 80 μm.

Evaluation rank of haze ◎: Haze is less than 0.5% ○: Haze is less than 0.5 to 1.0% Δ: Haze is less than 1.0 to 1.5 x: Haze is 1.5 to 2.0% Less than xx: Haze is 2.0% or more Bright spot foreign matter Two polarizing plates are arranged in an orthogonal state (crossed Nicols) to block transmitted light, and each sample is placed between the two polarizing plates. The polarizing plate used was a glass protective plate. Light was irradiated from one side, and the number of foreign matters having a diameter of 0.01 mm or more per 1 cm ² was counted with an optical microscope (50 times) from the opposite side.

Evaluation rank of bright spot foreign matter A: Number of foreign matters 0 to 30/1 cm ²
○: The number of foreign matters is 31 to 50/1 cm ²
Δ: 51 to 80 foreign objects / 1 cm ²
X: The number of foreign matter is 81 to 100/1 cm ²
XX: Number of foreign matters is 101 or more / 1 cm ²

  Sample No. Regarding 101, it was impossible to produce a film because the pressure loss caused by the filter was too large. Sample No. For 113 and 119, since the shear stress was high, the retardation value was good. However, generation of haze and bright spot foreign matter was observed, and deterioration of film quality became a problem. The effectiveness of the present invention was confirmed.

Example 2
(Manufacture of cellulose ester film)
The cellulose esters shown in Table 2 were prepared, and each cellulose ester was dried in air at 130 ° C. for 2 hours under normal pressure, and allowed to cool to room temperature. To each cellulose ester, 0.5 part by mass of the compound represented by the general formula (I) shown in Table 2 with respect to the cellulose ester and 1.0 part by mass of ethylene glycol dicyclopropylcarboxylate as a plasticizer are added. 2 and heated and melted at a melting temperature of 220 ° C., melt-extruded from a T-shaped die, formed 10 m of unstretched cellulose ester, and further, at 160 ° C., 1.2 × 1. 2 to produce a cellulose ester film having a film thickness of 80 μm. 201-212. The shear stress during filtration was 0.08 MPa (the nominal filtration accuracy of the melt extruder filter was 10 μm, the filter thickness was 0.7 mm, and the filtration pressure was 5.6 MPa). As stabilizers, tris (2,4-di-t-butylphenyl) phosphite, n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, bis (2,2,6 , 6-Tetramethyl-4-piperidyl) sebacate in 1 part by mass with respect to cellulose ester, and 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole as cellulose as an ultraviolet absorber. 0.5 parts by mass was used with respect to the ester. The same leaf disk filter as in Example 1 was used as the filter. The shear stress, the nominal filtration accuracy of the filter, the filter thickness, and the filtration pressure were measured in the same manner as in Example 1.

Evaluation Each sample No. Table 2 shows the results of evaluations according to the same evaluation rank as in Example 1, which are applied to 201-212, tested for the retardation coefficient of variation (CV), haze, and bright spot foreign matter in the same manner as in Example 1.

A: Cellulose acetate propionate CAP482-20 (Eastman Chemical Co.)
B: Cellulose acetate butyrate CAB171-15 (manufactured by Eastman Chemical Co.)
C: Cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8)
D: Cellulose acetate propionate (acetyl group substitution degree 0.8, propionyl group substitution degree 2.0)
E: Cellulose acetate butyrate (acetyl group substitution degree 0.5, butyryl group substitution degree 2.1)
F: Cellulose acetate butyrate (acetyl group substitution degree 1.0, butyryl group substitution degree 1.7)
Compound 1: 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetrakis-tert-butyldibenzo [d, f] [1.3 .2] Dioxaphosphin Compound 2: 6- [3- (3,5-Di-tert-butyl-4-hydroxyphenyl) propoxy] -2,4,8,10-tetrakis-tert-butyldibenzo [ d, f] [1.3.2] Dioxaphosphepine The effectiveness of the present invention was confirmed.

Example 3
(Manufacture of amorphous thermoplastic resin film)
Various amorphous thermoplastic resins shown in Table 3 were prepared as amorphous thermoplastic resins, dried under the conditions shown in Table 3, and then allowed to cool to room temperature. To each amorphous thermoplastic resin, 0.5 parts by mass of the compound represented by the general formula (I) shown in Table 4 with respect to the amorphous thermoplastic resin and the plasticizer shown in Table 3 were added, and FIG. Is melt-heated using the production apparatus shown in FIG. 1, melt-extruded from a T-shaped die, formed 10 m of an unstretched amorphous thermoplastic resin film, and then stretched at a stretch ratio of 1.2 × 1.2, Various amorphous thermoplastic resin films having a film thickness of 80 μm were prepared. 301 to 308. The melting temperature of polycarbonate is 230 ° C., the melting temperature of cycloolefin polymer (Nippon Zeon Co., Ltd. trade name: Zeonoa) is 240 ° C., and the melting temperature of polysulfone resin (Teijin Amoco Engineering Plastics, trade name: P-3500) is The melting temperature of 290 ° C. and polyethylene terephthalate (manufactured by Toray Industries, Inc.) was 295 ° C. The shear stress during filtration was 0.08 MPa (the nominal filtration accuracy of the melt extruder filter was 10 μm, the filter thickness was 0.7 mm, and the filtration pressure was 5.6 MPa). As stabilizers, tris (2,4-di-t-butylphenyl) phosphite, n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, bis (2,2,6 , 6-tetramethyl-4-piperidyl) sebacate with respect to cellulose ester, and 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole as a UV absorber. 0.5 parts by mass was used with respect to the amorphous thermoplastic resin. The same leaf disk filter as in Example 1 was used as the filter. The shear stress, the nominal filtration accuracy of the filter, the filter thickness, and the filtration pressure were measured in the same manner as in Example 1.

a: Polycarbonate b: Cycloolefin polymer (Nippon ZEON Co., Ltd., trade name: ZEONOR)
c: Polysulfone resin (manufactured by Teijin Amoco Engineering Plastics, trade name P-3500)
d: Polyethylene terephthalate Evaluation Each sample No. Table 4 shows the results of evaluations according to the same evaluation ranks as in Example 1 after being attached to 301 to 308, tested on the retardation coefficient of variation (CV), haze, and bright spot foreign matter in the same manner as in Example 1.

Compound 1: 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetrakis-tert-butyldibenzo [d, f] [1.3 .2] Dioxaphosphin Compound 2: 6- [3- (3,5-Di-tert-butyl-4-hydroxyphenyl) propoxy] -2,4,8,10-tetrakis-tert-butyldibenzo [ d, f] [1.3.2] Dioxaphosphepine The effectiveness of the present invention was confirmed.

It is an exploded schematic diagram which shows an example of a liquid crystal display device. It is a schematic diagram which shows an example of the manufacturing apparatus which manufactures the film for optics by a melt extrusion method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 101 Liquid crystal cell 102, 103 Polarizing plate 102b, 103b Polarizing plate protective film 102c, 103c Optical compensation film 2 Manufacturing apparatus 201 Melt extrusion machine 201a Main body 201b Hopper 201c Gear pump 201d Filter 202 T die 203 Cooling take-up machine 204 Winding Take-off machine

Claims (3)

After supplying amorphous thermoplastic resin to a melt extruder and melting it, it is filtered by a filtration device, and then manufactured by a melt extrusion method in which an amorphous thermoplastic resin melt is extruded from a molding die. In the film manufacturing method,
The filtration device has a filter with a nominal filtration accuracy of 3 to 10 μm,
A method for producing an optical film, characterized in that a value of a shear stress when the amorphous thermoplastic resin melt passes through the filter is 0.04 to 0.1 MPa. The method for producing an optical film according to claim 1, wherein the amorphous thermoplastic resin melt contains at least one compound having a phenol structure and a phosphite structure in the molecule. The method for producing an optical film according to claim 2, wherein the compound having the phenol structure and the phosphite structure in the molecule is represented by the following general formula (I).
(In the general formula (I), R ¹ , R ² , R ⁴ , R ⁵ , R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. Represents an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, and R ³ and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Represents a single bond, a sulfur atom or a —CHR ⁹ — group (R ⁹ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms). 8 represents an alkylene group or * —COR ¹⁰ — group (R ¹⁰ represents a simple bond or an alkylene group having 1 to 8 carbon atoms, and * represents that it is bonded to the oxygen side) Y and Z represent Either one is a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms, or 7 to 1 carbon atoms 2 represents an aralkyloxy group, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)