JP2006113551A - Polarizing plate protective film and manufacturing method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of a cellulose ester resin and to improve the mixability/dispersibility of an additive, in a method for obtaining a cellulose ester film for polarizing plate protection by a heat melting method. <P>SOLUTION: In a method for manufacturing a polarizing plate protective film obtained by mixing at least a cellulose ester resin and an organic additive, obtaining an integral molding, and melting it by heating, the molding is a cube having a size of 1 mm×1 mm×1 mm to 20 mm×20 mm×20 mm and the cellulose ester resin is contained in the molding in a state of particles. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polarizing plate protective film and a method for producing the same.

  As the polarizing plate protective film, a cellulose ester resin is used. This is because the cellulose ester film is optically and physically excellent as a polarizing plate protective film. However, the film production method is generally a casting film production method using a halogen-based organic solvent. The use of halogen-based organic solvents is being restricted from the environmental and safety aspects. In addition, as long as the halogen-based organic solvent is used in the production process, a slight amount remains even if it is removed in a subsequent step. This residual solvent causes problems such as a decrease in product durability.

  On the other hand, a melt casting method has been proposed as a method for producing a cellulose ester film that does not use a halogen-based organic solvent (see, for example, Patent Document 1). The melt casting method is a method in which a cellulose ester resin is extruded while being melted by heating to form a film. Since the cellulose ester resin is generally a material that easily deteriorates due to heat, mechanical stress or the like, the cellulose ester resin deteriorates in this heating and melting step, and it is difficult to obtain a film having sufficient mechanical strength. As a device used in the heating and melting step, there are generally a single screw extruder and a twin screw extruder. A twin-screw extruder is a machine that rotates two shafts and extrudes while applying mechanical stress. Since mechanical stress is applied, the mixing / dispersing performance of the additive is superior to that of the single screw extruder, but it is disadvantageous for deterioration of the cellulose ester resin. For deterioration of cellulose ester resin, a single-screw extruder with relatively low mechanical stress is more advantageous. However, since it is a machine that extrudes by the rotational force of a single shaft, the additive content is higher than that of a twin-screw extruder. Mixing / dispersing performance is poor.

A method for producing a cellulose ester film having high mixing and dispersibility of additives while using a single-screw extruder has been proposed (see, for example, Patent Documents 2 and 3). All of these obtained pellets by heating and melting the cellulose ester resin and the additive to 200 ° C. or higher with a twin screw extruder, and then remelting with a single screw extruder to obtain a film. Yes. In these methods, degradation of the cellulose ester resin is considerably accelerated by mechanical stress when the cellulose ester resin is given a two-time thermal history and further pelletized by a twin screw extruder. When the deterioration of the cellulose ester resin is promoted, the molecular weight mainly decreases and the mechanical strength decreases. This causes problems not only in product quality, but also in reuse of crushed products generated during production as raw materials.
JP 2000-352620 A JP-A-9-241425 JP 11-255959 A

  The present invention has been made in view of the above circumstances, and in the method of obtaining a polarizing plate-protecting cellulose ester film by a heating and melting method, suppressing deterioration of the cellulose ester resin and improving the mixing / dispersibility of additives. With the goal.

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

  (1) In a method for producing a polarizing plate protective film obtained by mixing at least a cellulose ester resin and an organic additive, obtaining an integral molded product, and then melting by heating, the size of the molded product is 1 mm × The manufacturing method of the polarizing plate protective film characterized by being in the range of 1 mm x 1 mm-20 mm x 20 mm x 20 mm cube, and containing the cellulose ester resin in the molded product in a particle state.

  (2) The organic additive in the molded product contains a maximum dispersed particle size (eDmax) of 100 μm or less, and the weight average particle size (cDw50) of the cellulose ester resin in the particle state and the maximum dispersed particle size ( eDmax) is in the following relationship: The method for producing a polarizing plate protective film as described in (1) above.

cDw50> eDmax
(3) The method for producing a polarizing plate protective film as described in (1) or (2) above, wherein the cellulose ester resin has a weight average particle diameter (cDw50) in the range of 1 to 200 μm.

  (4) The polarizing plate as described in any one of (1) to (3) above, wherein the organic additive has a maximum dispersed particle size in a polarizing plate protective film of 0.1 μm or less. A method for producing a protective film.

  (5) 1 g of the cellulose ester resin was added to 20 ml of pure water (electric conductivity 1 μS / cm or less, pH 6.8), and the pH was 6 to 7 when stirred in a nitrogen atmosphere at 25 ° C. for 1 hr. The method for producing a polarizing plate protective film according to any one of (1) to (4), wherein the electrical conductivity is 1 to 100 μS / cm.

(6) The polarizing plate protective film according to any one of (1) to (5), wherein the cellulose ester resin has a volume resistivity value of 10 ¹¹ to 10 ¹⁵ Ω · cm. Production method.

  (7) The weight average molecular weight of the molded product is Mwt, and the weight average molecular weight of the obtained film is Mwf. The molecular weight retention rate Mwr (%) = Mwf / Mwt × 100 is 85 to 100%. The method for producing a polarizing plate protective film according to any one of (1) to (6).

  (8) A polarizing plate protective film produced by the method for producing a polarizing plate protective film according to any one of (1) to (7).

  According to the present invention, in a method for obtaining a polarizing plate-protecting cellulose ester film by a heating and melting method, it is possible to suppress deterioration of the cellulose ester resin and improve the mixing / dispersibility of additives.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto. Note that the description of simply preferred indicates that it is preferred for the purposes of the present invention.

  The polarizing plate protective film of the present invention is a cellulose ester film formed by melt casting.

  The melt casting in the present invention is defined as melt casting in which a cellulose ester is heated and melted to a temperature exhibiting fluidity without using a solvent, and then the fluid cellulose ester is cast. More specifically, the heating and melting molding method can be classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these, in order to obtain an optical film excellent in productivity and the like, the melt extrusion method is excellent. Here, after the film constituent material is heated to exhibit its fluidity, extrusion film formation on a drum or an endless belt is included in the method for producing a molten film of the present invention as a melt casting film formation method.

(Cellulose ester)
The cellulose ester resin according to the present invention is the single or mixed acid ester of cellulose which shows the structure of a cellulose ester and contains at least one of a fatty acyl group and a substituted or unsubstituted aromatic acyl group. .

  Hereinafter, cellulose esters useful for satisfying the object of the present invention will be exemplified, but the present invention is not limited thereto.

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. Amido 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 ( _{O-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, include -O-SiH (-R) ₂ and -O-Si (-R) _3. R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably 1 to 5, more preferably 1 to 4, more preferably 1 to 3, and most preferably 1 or 2. 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 ester of 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, Examples include 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. When the aromatic ring is a benzene ring in the above-described aromatic acyl group, the substituent of the benzene ring Are exemplified.

  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 linked together 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, which is used as the structure used in the cellulose ester of the present invention. These may be a single or mixed acid ester of cellulose, or a mixture of two or more cellulose esters.

  In the cellulose ester constituting the polarizing plate protective film of the present invention, at least one selected from cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose phthalate It is preferable that

  Among these, particularly preferable cellulose esters include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

  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 them, 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 are preferable. The portion not substituted with the acyl group is usually present as a hydroxyl group. These can be synthesized by known methods.

  Furthermore, the cellulose ester used in the present invention preferably has a weight average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 5.5, particularly preferably 2.0 to 5.0, Preferably it is 2.5-5.0, More preferably, the cellulose ester of 3.0-5.0 is used preferably.

  The cellulose ester raw material cellulose used in the present invention may be wood pulp or cotton linter, and the wood pulp may be softwood or hardwood, but softwood is more preferred. 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.

  The cellulose ester resin according to the present invention was charged with 1 g in 20 ml of pure water (electric conductivity 0.1 μS / cm or less, pH 6.8), and had a pH of 6 when stirred in a nitrogen atmosphere at 25 ° C. for 1 hr. It is preferable that the electric conductivity is 1 to 100 μS / cm in order to stably obtain the effects of the present invention. If the pH is less than 6, the residual organic acid may promote cellulose degradation during heating and melting, and if the pH is higher than 7, hydrolysis may accelerate. In addition, when the electrical conductivity is 100 μS / cm or more, since a relatively large amount of residual ions are present, it is considered to be a factor for degrading cellulose during heating and melting.

The volume specific resistance value of the cellulose ester resin is preferably 10 ¹¹ to 10 ¹⁵ Ω · cm. Further, it is more preferably 10 ¹³ to 10 ¹⁵ Ω · cm. Since the cellulose ester resin has high hygroscopicity, it is preferable that the cellulose ester resin be sufficiently dried to remove moisture as much as possible. Further, it is preferable to remove residual organic acid as much as possible. When the volume resistivity is lower than 10 ¹¹ Ω · cm, the cellulose ester resin may be deteriorated during heating and melting due to the influence of residual organic acid and moisture. Although a molded product of 10 ¹⁵ Ω · cm could not be obtained, it is considered that the higher the volume resistivity value, the more advantageous for deterioration.

(Organic additives)
The polarizing plate protective film according to the present invention preferably contains an organic additive. Organic additives include plasticizers, ultraviolet absorbers, antioxidants, acid scavengers, light stabilizers, retardation control agents, polymer materials, and the like.

  Hereinafter, the additive will be described in more detail.

(Plasticizer)
It is preferable to add a compound known as a plasticizer to the polarizing plate protective film of the present invention from the viewpoint of improving the film, such as improving mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability. . Further, in the melt casting method carried out in the present invention, the purpose of lowering the melting temperature of the film constituting material by adding a plasticizer rather than the glass transition temperature of the cellulose ester used alone, or the plasticizer than the cellulose ester at the same heating temperature. The purpose of reducing the viscosity of the film-constituting material containing is included.

  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.

  If the cellulose ester alone is lower than the glass transition temperature, the fluidity for forming a film is not exhibited. However, the cellulose ester has a lower elastic modulus or viscosity due to the absorption of heat at a glass transition temperature or higher, and exhibits fluidity. In order to melt the film constituent material, the plasticizer to be added preferably has a melting point or glass transition temperature lower than the glass transition temperature of the cellulose ester in order to satisfy the above-mentioned purpose.

  As the plasticizer used in the present invention, for example, phosphate ester derivatives and carboxylic acid ester derivatives are preferably used. Further, a polymer obtained by polymerizing an ethylenically unsaturated monomer having a weight average molecular weight of 500 to 10,000 described in JP-A-2003-12859, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, or cyclohexyl An acrylic polymer having a group in the side chain is also preferably used.

  Examples of phosphoric acid ester derivatives include phosphoric acid ester plasticizers, ethylene glycol ester plasticizers, glycerin ester plasticizers, diglycerin ester plasticizers (fatty acid esters), polyhydric alcohol esters. Examples thereof include a plasticizer, a dicarboxylic acid ester plasticizer, a polyvalent carboxylic acid ester plasticizer, and a polymer plasticizer. Of these, polyhydric alcohol ester plasticizers, dicarboxylic acid ester plasticizers and polycarboxylic acid ester plasticizers are preferred. Further, the plasticizer may be a liquid or a solid, and is preferably colorless due to restrictions on the composition. Thermally, it is preferably stable at a higher temperature, and the decomposition start temperature is preferably 150 ° C. or higher, more preferably 200 ° C. or higher. The addition amount may be as long as the optical properties and mechanical properties are not adversely affected, and the blending amount is appropriately selected within the range not impairing the object of the present invention, and preferably 0.001 with respect to 100 parts by mass of the polymer according to the present invention. -50 mass parts, More preferably, it is 0.01-30 mass parts. 0.1-15 mass% is especially preferable.

  Hereinafter, the plasticizer used in the present invention will be further described. Specific examples are not limited to these examples.

  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 cresylphenyl 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, and 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, and 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, and is 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.

  Ethylene glycol ester plasticizer: Specifically, ethylene glycol alkyl ester plasticizers such as ethylene glycol diacetate and ethylene glycol dibutyrate, ethylene glycol dicyclopropyl carboxylate, ethylene glycol dicyclohexyl carboxylate and the like Examples include ethylene glycol cycloalkyl ester plasticizers 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, a mixture of alkylate group, cycloalkylate group and arylate group may be used, and these substituents may be covalently bonded. 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. May be introduced into a part of the molecular structure of the additive.

  Glycerin ester plasticizers: Specifically, glycerol alkyl esters such as triacetin, tributyrin, glycerol diacetate caprylate, glycerol oleate propionate, and glycerin cycloalkyl esters such as glycerol tricyclopropyl carboxylate and glycerol tricyclohexyl carboxylate Glyceryl aryl esters such as glycerin tribenzoate and glycerin 4-methylbenzoate, diglycerin tetraacetylate, diglycerin tetrapropionate, diglycerin acetate tricaprylate, diglycerin alkyl esters such as diglycerin tetralaurate, di Diglycerides such as glycerin tetracyclobutylcarboxylate and diglycerin tetracyclopentylcarboxylate Emissions cycloalkyl esters, 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 mix of alkylate group, cycloalkylcarboxylate group, and arylate group, and these substituents may be bonded by a covalent bond. Furthermore, the glycerin or diglycerin part may be substituted, and the partial structure of the glycerin ester or diglycerin ester may be part of the polymer or regularly pendant, and may be an antioxidant or an acid scavenger. Or may be introduced into a part of the molecular structure of an additive such as an ultraviolet absorber.

  Polyhydric alcohol ester plasticizer: Specific examples 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 mix 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.

  Dicarboxylic acid ester plasticizers: Specifically, alkyldocarboxylic acid alkyl ester plasticizers such as didodecyl malonate (C1), dioctyl adipate (C4), dibutyl sebacate (C8), dicyclopentyl succinate, Alkyl dicarboxylic acid cycloalkyl ester plasticizers such as dicyclohexyl adipate, alkyl dicarboxylic acid aryl ester plasticizers such as diphenyl succinate and di4-methylphenyl glutarate, dihexyl-1,4-cyclohexanedicarboxylate, Cycloalkyldicarboxylic acid alkyl ester plasticizers such as didecylbicyclo [2.2.1] heptane-2,3-dicarboxylate, dicyclohexyl-1,2-cyclobutanedicarboxylate, dicyclopropyl-1,2 Cycloalkyldicarboxylic acid cycloalkyl ester plasticizers such as cyclohexyl dicarboxylate, aryl cycloalkyldicarboxylates such as diphenyl-1,1-cyclopropyldicarboxylate, di2-naphthyl-1,4-cyclohexanedicarboxylate Ester plasticizers, aryl dicarboxylic acid alkyl ester plasticizers such as diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate and di-2-ethylhexyl phthalate, and aryl dicarboxylic acid cycloalkyls such as dicyclopropyl phthalate and dicyclohexyl phthalate Examples include ester plasticizers and aryl dicarboxylic acid aryl ester plasticizers such as diphenyl phthalate and di4-methylphenyl phthalate. 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, and these substituents may be bonded together by a covalent bond. Further, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. In addition, the partial structure of phthalate ester may be part of the polymer or regularly pendant to the polymer, and may be part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. It may be introduced.

  Polycarboxylic acid ester plasticizers: Specifically, alkyl polycarboxylic acid alkyl ester plastics such as tridodecyl tricarbarate and tributyl-meso-butane-1,2,3,4-tetracarboxylate Agents, alkyl polyvalent carboxylic acid cycloalkyl ester type plasticizers such as tricyclohexyl tricarbarate, tricyclopropyl-2-hydroxy-1,2,3-propanetricarboxylate, triphenyl 2-hydroxy-1,2 Alkyl polycarboxylic acid aryl ester plasticizers such as 1,3-propanetricarboxylate, tetra-3-methylphenyltetrahydrofuran-2,3,4,5-tetracarboxylate, tetrahexyl-1,2,3,4 -Cyclobutane tetracarboxylate, tetrabutyl-1,2, 1,4-cyclopentanetetracarboxylate and other cycloalkyl polycarboxylic acid alkyl ester plasticizers, tetracyclopropyl-1,2,3,4-cyclobutanetetracarboxylate, tricyclohexyl-1,3,5-cyclohexyl Cycloalkyl polycarboxylic acid cycloalkyl ester plasticizers such as tricarboxylate, triphenyl-1,3,5-cyclohexyl tricarboxylate, hexa-4-methylphenyl-1,2,3,4,5,6 -Cycloalkyl polycarboxylic acid aryl ester plasticizers such as cyclohexyl hexacarboxylate, tridodecylbenzene-1,2,4-tricarboxylate, tetraoctylbenzene-1,2,4,5-tetracarboxylate, etc. Aryl polycarboxylic acid Lester ester plasticizer, aryl polyvalent carboxylic acid cycloalkyl ester plasticizer tri such as tricyclopentylbenzene-1,3,5-tricarboxylate, tetracyclohexylbenzene-1,2,3,5-tetracarboxylate Aryl polycarboxylic acid aryl ester-based plasticizers such as phenylbenzene-1,3,5-tetracartoxylate and hexa-4-methylphenylbenzene-1,2,3,4,5,6-hexacarboxylate Can be mentioned. 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, and these substituents may be bonded together by a covalent bond. Further, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. In addition, the partial structure of phthalate ester may be part of the polymer or regularly pendant to the polymer, and may be part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. It may be introduced.

  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, polystyrene, styrene polymers such as poly-4-hydroxystyrene, polybutylene succinate, 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 arises in volatility, and if it exceeds 500,000, the plasticizing ability is lowered, which adversely affects the mechanical properties of the cellulose ester derivative composition. 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, and other plasticizers, antioxidants, acid scavengers, ultraviolet absorbers, slip agents, matting agents, and the like may be included.

  The addition amount of these compounds is preferably used in the range of 0.5% by mass to less than 50% by mass, more preferably 1% by mass to 30% by mass with respect to the resin in which the plasticizer constitutes the film. %, More preferably in the range of 1% by mass to less than 11% by mass. The addition amount of these compounds can be adjusted from the viewpoint of the above purpose.

  Among the plasticizers, it is generally preferable that no volatile component is generated during heat melting. Specific examples include non-volatile phosphate esters described in JP-A-6-501040. For example, among arylene bis (diaryl phosphate) esters and the above exemplified compounds, trimethylolpropane tribenzoate is preferable. It is not limited. When the volatile component is due to thermal decomposition of the plasticizer, the thermal decomposition temperature Td (1.0) of the plasticizer is higher than the melting temperature of the film-forming material when defined as the temperature at which the mass decreases by 1.0% by mass. Is required. This is because, for the above purpose, the plasticizer is added to the cellulose ester in a larger amount than other film constituent materials, and the presence of the volatile component has a great influence on the quality of the obtained film. The thermal decomposition temperature Td (1.0) can be measured with a commercially available differential thermogravimetric analysis (TG-DTA) apparatus.

  In addition, this invention expands the selection range of the said plasticizer generally considered preferable. That is, when the film constituent material is an integral molded product, the resin and the additive are in close contact with each other, and the contact area with air (especially oxygen and water) is reduced. Therefore, it is expected that the melting point of the film forming material and the thermal decomposition temperature of the plasticizer are lower than those of the single material, and the melting point of the film forming material is lowered and the thermal decomposition temperature of the plasticizer is increased. Further, the best mode in the film formation of the present invention is characterized by extruding at a temperature as low as possible in a short time. For example, the thermal decomposition temperature Td (1.0) of the plasticizer is the melting temperature of the film forming material. Even if it is lower, if the value is close to Td (1.0) = melting temperature of the film-forming material to melting temperature of the film-forming material−about 30 ° C., it is inferior to film quality such as mechanical strength. There is no.

(Antioxidant)
The antioxidant used in the present invention will be described.

  Antioxidants include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, heat-resistant processing stabilizers, oxygen scavengers, etc. Among them, phenolic antioxidants, particularly alkyl-substituted phenolic compounds Antioxidants are preferred. By blending these antioxidants, it is possible to prevent coloration and strength reduction of the molded product due to heat during molding or oxidative degradation without lowering transparency, heat resistance and the like. These antioxidants can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention, but the polymer 100 according to the present invention. Preferably it is 0.001-5 mass parts with respect to a mass part, More preferably, it is 0.01-1 mass part.

  As antioxidants, hindered phenol antioxidant compounds are known compounds, such as those described in columns 12-14 of US Pat. No. 4,839,405, such as 2, 6-dialkylphenol derivative compounds are included. Such compounds include those of the following general formula (1).

  In the above formula, R 1, R 2 and R 3 represent a further substituted or unsubstituted alkyl substituent. Specific examples of hindered phenol compounds include n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, n-octadecyl 3- (3,5-di-t-butyl- 4-hydroxyphenyl) -acetate, n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-tert-butyl-4-hydroxyphenylbenzoate, n-dodecyl 3, 5-di-t-butyl-4-hydroxyphenylbenzoate, neo-dodecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl β (3,5-di-t-butyl- 4-hydroxyphenyl) propionate, ethyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octade Sil α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n -Octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-phenylacetate, 2- (n- Octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (2- Hydroxyethylthio) ethyl 3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5-di-t-butyl-4) -Hydroxy-phenyl) propionate, 2- (n-octadecylthio) ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide N, N-bis- [ethylene 3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino N, N-bis- [ethylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2- (2-stearoyloxyethylthio) ethyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl 7- (3-methyl-5-tert-butyl-4- Hydroxyphenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5-di-tert-butyl-4-hydroxyl Nyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3,5-di-t-butyl-) 4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerin-1-n-octadecanoate-2,3-bis- (3 5-di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol-tetrakis- [3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate], 1,1,1 -Trimethylolethane-tris- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], sorbite Ruhexa- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl 7- (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, 2- Stearoyloxyethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol-bis [(3 ′, 5′-di-t-butyl-4-hydroxy Phenyl) propionate], pentaerythritol-tetrakis (3,5-di-t-butyl-4-hydroxyhydrocinnamate). Hindered phenolic antioxidant compounds of the above type are commercially available, for example, from Ciba Specialty Chemicals under the trade names “Irganox 1076” and “Irganox 1010”.

  Specific examples of other antioxidants include phosphorus antioxidants such as trisnonylphenyl phosphite, triphenyl phosphite, tris (2,4-di-tert-butylphenyl) phosphite, and dilauryl-3. , 3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythrityltetrakis (3-laurylthiopropionate), etc. System antioxidant, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5- Di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate 3,4-dihydro-2H-1-benzopyran compound, 3,3′-spirodichroman compound, 1,1-spiroindane compound, morpholine, thiomorpholine, thiomorpholine oxide, described in JP-B-08-27508, Examples thereof include thiomorpholine dioxide, compounds having a piperazine skeleton in the partial structure, oxygen scavengers such as dialkoxybenzene compounds described in JP-A No. 03-174150, and the like. These antioxidant partial structures 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 plasticizers, acid scavengers, and UV absorbers. May be.

(Acid scavenger)
The acid scavenger preferably comprises 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 various polyglycol diglycidyl ethers, particularly about 8-40 moles of ethylene oxide per mole of polyglycol. Glycol, diglycidyl ether of glycerol, metal epoxy compounds (such as those conventionally used in and together with vinyl chloride polymer compositions), epoxidized ether condensation products, diphenols of bisphenol A Glycidyl ether (i.e., 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester (especially an ester of an alkyl of about 4 to 2 carbon atoms of a fatty acid of 2 to 22 carbon atoms (e.g. butyl Epoxy stearate) ), And various epoxidized long chain fatty acid triglycerides and the like (e.g., epoxidized vegetable oils and other unsaturated natural oils, which may be represented and exemplified by compositions such as epoxidized soybean oil, sometimes epoxidized natural) These are referred to as glycerides or unsaturated fatty acids and these fatty acids 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 (2).

  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.

(Light stabilizer)
Light stabilizers include hindered amine light stabilizer (HALS) compounds, which are known compounds, such as columns 5-11 of US Pat. No. 4,619,956 and US Pat. , 839,405, as described in columns 3 to 5, including 2,2,6,6-tetraalkylpiperidine compounds, or acid addition salts thereof or complexes of them with metal compounds It is. Such compounds include those of the following general formula (3).

  In the above formula, R1 and R2 are H or a substituent. Specific examples of hindered amine light stabilizer compounds include 4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-benzyl. -4-hydroxy-2,2,6,6-tetramethylpiperidine, 1- (4-t-butyl-2-butenyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-stearoyl Oxy-2,2,6,6-tetramethylpiperidine, 1-ethyl-4-salicyloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6 6-pentamethylpiperidine, 1,2,2,6,6-pentamethylpiperidin-4-yl-β (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, -Benzyl-2,2,6,6-tetramethyl-4-piperidinyl maleate, (di-2,2,6,6-tetramethylpiperidin-4-yl) -adipate, (di- 2,2,6,6-tetramethylpiperidin-4-yl) -sebacate, (di-1,2,3,6-tetramethyl-2,6-diethyl-piperidin-4-yl) -sebacate, (di -1-allyl-2,2,6,6-tetramethyl-piperidin-4-yl) -phthalate, 1-acetyl-2,2,6,6-tetramethylpiperidin-4-yl-acetate, trimellitic acid- Tri- (2,2,6,6-tetramethylpiperidin-4-yl) ester, 1-acryloyl-4-benzyloxy-2,2,6,6-tetramethylpiperidine, dibutyl-malonic acid-di -(1,2,2,6,6-pentamethyl-piperidin-4-yl) -ester, dibenzyl-malonic acid-di- (1,2,3,6-tetramethyl-2,6-diethyl-piperidine- 4-yl) -ester, dimethyl-bis- (2,2,6,6-tetramethylpiperidine-4-oxy) -silane, tris- (1-propyl-2,2,6,6-tetramethylpiperidine- 4-yl) -phosphite, tris- (1-propyl-2,2,6,6-tetramethylpiperidin-4-yl) -phosphate, N, N′-bis- (2,2,6,6- Tetramethylpiperidin-4-yl) -hexamethylene-1,6-diamine, N, N′-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -hexamethylene-1,6- Diacetamide, 1-acetyl -4- (N-cyclohexylacetamide) -2,2,6,6-tetramethyl-piperidine, 4-benzylamino-2,2,6,6-tetramethylpiperidine, N, N'-bis- (2, 2,6,6-tetramethylpiperidin-4-yl) -N, N′-dibutyl-adipamide, N, N′-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -N , N′-dicyclohexyl- (2-hydroxypropylene), N, N′-bis- (2,2,6,6-tetramethylpiperidin-4-yl) -p-xylylene-diamine, 4- (bis-2 -Hydroxyethyl) -amino-1,2,2,6,6-pentamethylpiperidine, 4-methacrylamide-1,2,2,6,6-pentamethylpiperidine, α-cyano-β-methyl-β- [N- (2,2 6,6-tetramethyl-piperidin-4-yl)] - amino - acrylic acid methyl ester. Examples of preferred hindered amine light stabilizers include the following HALS-1 and HALS-2.

  These hindered amine light resistance stabilizers can be used alone or in combination of two or more, and used together with these hindered amine light resistance stabilizers and additives such as plasticizers, acid scavengers, and UV absorbers. Alternatively, it may be introduced into a part of the molecular structure of the additive. The blending amount is appropriately selected within a range not impairing the object of the present invention, but is preferably 0.01 to 20 parts by mass, more preferably 0.02 to 15 parts with respect to 100 parts by mass of the polymer according to the present invention. Part by mass, particularly preferably 0.05 to 10 parts by mass.

(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. 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, Unexamined-Japanese-Patent No. 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.

(Retardation control agent)
In the polarizing plate protective film of the present invention, an alignment film is formed to provide a liquid crystal layer, and the polarizing plate protective film and the retardation derived from the liquid crystal layer are combined to provide an optical compensation capability, thereby improving the liquid crystal display quality. Polarizing plate processing may be performed. As the compound to be added for adjusting the retardation, an aromatic compound having two or more aromatic rings as described in the specification of European Patent 911,656A2 may be used as a retardation control agent. I can do it. 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. Particularly preferred is an aromatic heterocycle, and the aromatic heterocycle is generally an unsaturated heterocycle. Of these, a 1,3,5-triazine ring is particularly preferred.

(Polymer material)
In the polarizing plate protective film of the present invention, a polymer material other than cellulose ester or an oligomer may be appropriately selected and mixed. The above polymer materials and oligomers are preferably those having excellent compatibility with the cellulose ester, and the transmittance when formed into a film is 80% or more, more preferably 90% or more, and further preferably 92% or more. The purpose of mixing at least one of polymer materials and oligomers other than cellulose ester includes meanings for controlling viscosity at the time of heating and melting and improving film physical properties after film processing. In this case, it can be included as the above-mentioned other additives.

(Matting agent)
The polarizing plate protective film of the present invention can be added with fine particles such as a matting agent in order to impart slipperiness, and examples of the fine particles include inorganic compound fine particles and organic compound fine particles. 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, aluminum silicate, Examples thereof include 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 substance, but such particles are preferred because they 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 the cellulose ester film in order to generate irregularities of 0.01 to 1.0 μm on the surface of the cellulose ester film. The content of the fine particles in the cellulose ester is preferably 0.005 to 0.3% by mass with respect to the cellulose ester.

  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 film used as the matting agent can be used for another purpose to improve the strength of the film. The presence of the fine particles in the film can also improve the orientation of the cellulose ester itself constituting the polarizing plate protective film of the present invention.

(Molded product manufacturing method and size)
Examples of the method for producing the molded product include a method for obtaining a tablet-shaped molded product by compressing under pressure, a method for obtaining a pellet-shaped molded product by heating and compressing, and the like.

  As a method for obtaining a tablet-like molded product, it is necessary to apply pressure, but after obtaining a plate-shaped molded product using a press machine or the like, a desired size is obtained by methods such as cutting and die cutting. After preparing a sample in a cylindrical molding machine, insert a piston with the same diameter as the cylindrical molding machine and press to obtain a rod-shaped molding, then cut it into the desired size The method of doing is mentioned.

  FIG. 1 shows an example of a jig for forming a molded product used in the example.

A stainless steel spacer having a mouth shape (thickness 5 to 50 mm) is placed on a stainless steel plate having a mirror surface property, and the resulting additive-containing cellulose ester resin fine particles are placed in a recess made of the spacer. After smoothing with a blade, a stainless steel plate having a predetermined thickness (10 mm to 25 mm) is fitted inside the mouth-shaped stainless steel spacer (recessed recess). Pressing is performed under the conditions of room temperature (20 to 25 ° C.), a pressure of 1 to 4 × 10 ⁷ Pa, and a range of 5 to 15 minutes with a press machine to obtain a plate-like additive-containing cellulose ester resin molding. In order to make the molded product have a desired thickness, the thickness of a jig such as a spacer is appropriately adjusted. Further, if necessary, the above-described operation is repeated several times to adjust the target thickness.

The obtained plate-shaped molded product was transferred to another stainless steel plate, and a single-sided die-cutting with many square ridges was placed (shown in FIG. 1), pressure of 1-6 × 10 ⁶ Pa, 1-5 Pressurization is performed under conditions in the range of minutes, and a square shaped product of the desired size can be obtained.

  As a method for obtaining a pellet-shaped molded product, a rod-shaped pellet is obtained by melt-extruding at a temperature not lower than the glass transition temperature of the cellulose ester resin and a melting point + 30 ° C. or lower with a twin-screw extruder, and then having a desired size Examples include a method of cutting by the method described above.

  Since the cellulose ester resin is a material that is significantly deteriorated by heat, a method of molding at a temperature that does not deteriorate (a method of obtaining a tablet-like molded product) is preferable.

  The temperature at which the tablet-like molded product is obtained is not particularly limited as long as the cellulose does not deteriorate. Preferably it is below the glass transition temperature (Tg) of cellulose, More preferably, it is below Tg minus 50 degreeC. Since the temperature may rise during pressure molding, it is preferable to press while cooling. In the case of a material with significant deterioration, it is preferable to press at 0 ° C. or lower.

In order to obtain the effects of the present invention, the size of the molded product obtained by mixing the cellulose ester resin and the organic additive is in the range of 1 mm × 1 mm × 1 mm to 20 mm × 20 mm × 20 mm cube. It is. In the melt extrusion method, if it is smaller than 1 mm × 1 mm × 1 mm, blocking will occur at the time of molding, and the supply will not be stable. If it is larger than 20 mm × 20 mm × 20 mm, the melting and pulverization properties of the molded product will be poor. There is a risk of clogging at the inlet, resulting in a significant decrease in productivity. On the other hand, if the size is smaller than 1 mm × 1 mm × 1 mm, the specific surface area of the molded product increases, so the contact area with air (especially oxygen and water) also increases, cellulose easily deteriorates, the molecular weight decreases, and the machine There is a risk that the mechanical strength will decrease. In the pressure heating and melting method, if it is larger than 20 mm × 20 mm × 20 mm, it becomes difficult to obtain a film having a small film thickness (100 μm or less). In addition, the film thickness is likely to be uneven. (Thickness accuracy is degraded.)
When formed into a molded product, the resin and the additive are in close contact with each other, so that the mixing / dispersibility is enhanced. Moreover, since the contact area with air (especially oxygen and water) becomes small, it is advantageous also for deterioration of a cellulose.

  In order to obtain the effect of the present invention, it is necessary for the cellulose ester resin in the molded product to be in a particle state in order to obtain the effect of the present invention, and that the maximum dispersed particle diameter of the organic additive is 100 μm or less. preferable. Moreover, there is no problem that a part of the organic additive penetrates into the cellulose ester resin particles. When a plurality of types of organic additives are used, each of them may be in a particle state or an organic additive may be in a mixed state. Among organic additives, the plasticizer having the largest added amount is generally the main component of particles having the maximum dispersed particle size.

  When it is going to obtain a cellulose-ester film by the heat-melting method, the direction which manufactured as low temperature and short residence time as possible can obtain a favorable film with little deterioration. However, when the maximum dispersed particle size of the organic additive exceeds 100 μm, when trying to obtain a film under good conditions, the additive has poor meltability, resulting in the dispersibility of the additive in the resulting film. There is a risk of getting worse. If the maximum dispersed particle size of the organic additive in the molded product is 100 μm or less, no matter how small, the dispersibility of the organic additive in the film is not adversely affected.

  The cellulose ester resin in the molded product preferably has a weight average particle diameter in the range of 1 to 200 μm for dispersibility at the time of melting and film uniformity. In order to make the weight average particle diameter within this range, it is preferable to make it within the above range by selecting the cellulose ester resin to be used, and in the case of large particles, by crushing. In particular, when it is desired to add an organic additive at a high concentration of 10% by mass or more, it is effective for the uniformity of the film that the cellulose ester resin has a weight average particle diameter in the range of 1 to 200 μm.

  The weight-average particle size cDw50 of the cellulose ester resin is preferably a condition for obtaining the effect of the present invention so that the relationship of cDw50> eDmax is satisfied when the maximum dispersed particle size of the organic additive is eDmax. In the case of cDw50 ≦ eDmax, a large number of organic additives having a particle size larger than the particle size of the cellulose ester resin are present, so that the dispersibility of the organic additive in the molded product is deteriorated. The effect of the present invention is presumed that the surface of the cellulose ester resin particles in the molded product is coated with an organic additive as particles or impregnated to achieve a uniform dispersion state when heated and melted.

  The particle size of the cellulose ester resin is adjusted by a dry pulverization method, an emulsion dispersion method, a spray dry method, or the like.

  The dry pulverization method is a method in which a cellulose ester resin is directly pulverized using a jet mill, a hammer-type cutter mill or the like, and adjusted to a desired particle size.

  In the emulsification dispersion method, a cellulose ester resin and an organic additive are added to a solvent such as ethyl acetate, mixed and dispersed with a stirrer to obtain a uniform cellulose ester resin composition, and then a dispersing agent such as sodium polyacrylate, alkyl diphenyl ether. The resin composition is gradually added dropwise to a dispersion medium solution in which a dispersion aid such as sodium disulfonate is dissolved to obtain an emulsified dispersion, and this solution is stirred and washed / filtered to obtain cellulose ester fine particles. Is the method.

  The spray drying method is a method of obtaining a powder by spraying a solution in which a desired substance is dissolved with a spray and drying with hot air. A desired particle size can be obtained by controlling the concentration of the spray solution, the shape of the spray nozzle, the spray speed, the temperature and speed of the drying air, and the like. In general, a powder having a small particle diameter can be obtained by controlling the droplet diameter at the time of spraying to be small, for example, by diluting the solution concentration and increasing the gas / liquid ratio with a two-fluid nozzle. As the apparatus, a spray dryer manufactured by Okawara Koki Co., Ltd. can be used.

  The particle size adjustment of organic additives and dispersion mixing with cellulose acetate propionate can be performed using the dry method and the emulsification dispersion method, and can be further prepared using a spray adsorption method or the like.

  The spray adsorption method is a method in which a cellulose ester resin is put into a mixer and stirred, and an organic additive is dissolved in a solvent and sprayed with a spray, and the organic additive is changed by changing the spraying conditions. Particle diameter adjustment and dispersion mixing with cellulose.

(Film formation)
The cellulose ester and additive mixture of the present invention is hot-air dried or vacuum-dried, then melt extruded, extruded into a film form from a T-shaped die, brought into close contact with a cooling drum by an electrostatic application method, etc., cooled and solidified. A stretched film can be obtained. The temperature of the cooling drum is preferably maintained at 90 to 150 ° C.

  Melt extrusion may be used by connecting a single screw extruder, a twin screw extruder, and a single screw extruder downstream of the twin screw extruder. From the viewpoint of the mechanical properties and optical properties of the obtained film, the single screw extruder is used. Is preferably used. Furthermore, it is preferable to replace or depressurize the raw material supply and melting processes such as the raw material tank, the raw material charging section, and the inside of the extruder with an inert gas such as nitrogen gas.

  In particular, a method of heating and melting without giving mechanical stress as much as possible is preferable to pay attention when producing a film. Examples of existing apparatuses include a single screw extruder and a hot press machine. In the case of a single screw extruder, it is desirable to extrude at a low temperature for a short time as long as it can be obtained at a temperature at which a transparent film can be obtained. In the path from the inlet to the die, it is desirable to set the glass transition temperature: Tg to the melting point: Tm of the cellulose ester resin, and it is preferable to raise the temperature stepwise as the die approaches. The temperature of the die is preferably set to Tm to Tm + 30 ° C. This is because the degradation of the cellulose ester resin is accelerated by heat, so that the degradation is suppressed by extruding at as low a temperature as possible. However, since it is necessary for the die to sufficiently melt the cellulose ester resin, a temperature higher than the melting point is required. In the path from the inlet to the die, when the temperature is in the vicinity of the melting point, the cellulose ester resin is significantly deteriorated. When the temperature of the die is lower than the melting point, the transparency and flatness of the resulting film are inferior, and when the melting point is higher than + 30 ° C., the deterioration may be significant.

  The residence time (extrusion time) is preferably as short as possible. In this experimental machine, 20 to 360 seconds are preferable, and more preferably 20 to 60 seconds. If the residence time is long, the deterioration may be remarkable, and if it is too short, the melting may be insufficient. The residence time is adjusted by the rotational speed of the shaft, the viscoelasticity of the molded product, the heating temperature, and the like.

  In the present invention, in the step of obtaining a molded product, a good film can be obtained also by heating at the time of pressurization using a hot press machine. For example, a film can be easily obtained by adjusting the thickness of the spacer used at the time of pressure molding to a desired film thickness and heating it to the vicinity of the melting point of the cellulose ester resin.

  The temperature during the melt extrusion of the present invention is preferably in the range of 150 to 250 ° C. Furthermore, it is preferable that it is the range of 200-240 degreeC.

  The maximum dispersed particle size of the organic additive in the obtained polarizing plate protective film is preferably 0.1 μm or less. Among organic additives, it is preferable that the maximum dispersed particle size of the plasticizer having the largest content is generally 0.1 μm or less. When the maximum dispersed particle size of the additive in the obtained film is 0.1 μm or more, the mechanical strength is lowered due to insufficient dispersibility of the additive. In the case of 0.1 μm or less, no matter how small it is, there is no particular problem in reducing the mechanical strength.

  It is preferable that the molecular weight retention rate Mwr (%) = Mwf / Mwt × 100 is 85 to 100% when the weight average molecular weight of the molded product is Mwt and the weight average molecular weight of the obtained film is Mwf. When Mwr is 85% or less, the molecular weight of the cellulose ester resin is too low to obtain sufficient mechanical strength.

  The cellulose ester film for a polarizing plate protective film of the present invention is particularly preferably a film stretched in the width direction or the film forming direction.

  The unstretched film peeled off from the cooling drum described above is heated within a range of Tg + 100 ° C. from the glass transition temperature (Tg) of the cellulose ester via a heating device such as a plurality of roll groups and / or an infrared heater, It is preferable to perform single-stage or multistage longitudinal stretching. Next, the cellulose ester film stretched in the longitudinal direction obtained as described above is preferably stretched transversely 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 stretching 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 of Tg-40 ° C. or higher at a temperature equal to or lower than the final transverse stretching temperature 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 perform 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.

  More optimal conditions of these heat setting conditions, cooling, and relaxation treatment conditions vary depending on the cellulose ester constituting the film, so the physical properties of the obtained biaxially stretched film should be measured and adjusted appropriately to have desirable characteristics. It may be determined by.

  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 a raw material for the same type of film or for different types of film. It may be reused as a raw material.

(Stretching operation, refractive index control)
When the polarizing plate protective film of the present invention is used as a retardation film, the refractive index can be controlled by a stretching operation. As the stretching operation, the refractive index is controlled within a preferable range by stretching 1.0 to 2.0 times in one direction of the cellulose ester and 1.01 to 2.5 times in the direction perpendicular to the film plane. I can do it.

  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 becomes difficult and breakage may occur.

  For example, when the film is stretched in the direction of melting and casting, if the contraction 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 is sometimes seen when the tenter method is used, but it is a phenomenon that occurs when the film is stretched in the width direction, causing contraction force at the center of the film and the ends being fixed. It is thought to be called a phenomenon. Even in this case, by stretching in the casting direction, the bowing phenomenon can be suppressed, and the distribution of the width retardation can be reduced.

  Furthermore, the film thickness fluctuation | variation of the film obtained can be reduced by extending | stretching in the biaxial direction orthogonal to each other. If the film thickness variation of the polarizing plate protective film is too large, the retardation will be uneven, and unevenness such as coloring may be a problem when used in a liquid crystal display.

  The film thickness variation of the cellulose ester 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 cellulose ester that obtains positive birefringence with respect to stress is used, the slow axis of the polarizing plate protective film can be provided in the width direction by stretching in the width direction. In this case, in the present invention, in order to improve display quality, the slow axis of the polarizing plate protective film is preferably in the width direction, and (stretch ratio in the width direction)> (stretch ratio in the casting direction) It is necessary to satisfy.

  There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination. In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

  It is preferable to perform the width maintenance or the transverse stretching in the film forming process by a tenter, and it may be a pin tenter or a clip tenter.

  As for the thickness of the polarizing plate protective film of this invention, 10-500 micrometers is preferable. In particular, it is preferably 20 μm or more, 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 polarizing plate protective film is thicker than the above-mentioned region, the polarizing plate after polarizing plate processing becomes too thick, so that it is not suitable for a thin and lightweight purpose in a liquid crystal display used for a notebook computer or a mobile electronic device. On the other hand, if it is thinner than the above-mentioned region, it is not preferable because it becomes difficult to develop retardation, the moisture permeability of the film becomes high, and the ability to protect the polarizer from humidity decreases.

  When the slow axis or the fast axis of the polarizing plate protective film of the present invention is present in the film plane and the angle formed with the film forming direction is θ1, θ1 is preferably −1 ° or more and + 1 ° or less, − More preferably, it is 0.5 ° or more and + 0.5 ° or less. This θ1 can be defined as an orientation angle, and θ1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).

  Each of θ1 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in a color liquid crystal display device.

(Functional layer)
In producing the polarizing plate protective 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, a barrier layer, an optical compensation layer, etc. The functional 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.

  Moreover, the cellulose ester film of a laminated structure can also be produced by co-extruding compositions containing cellulose resins having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent. For example, a cellulose ester 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.

(Polarizer)
The manufacturing method of the polarizing plate which has a polarizing plate protective film of this invention is not specifically limited, It can manufacture by a general method. The obtained polarizing plate protective film was treated with an alkali, and a polyvinyl alcohol film was immersed and stretched in an iodine solution, using a completely saponified polyvinyl alcohol aqueous solution on both sides of the polarizer, and polarizing plate protective films on both sides of the polarizer. There is a method of bonding, and at least one side is preferable from the viewpoint that the polarizing plate protective film of the present invention can be directly bonded to the polarizer.

  Further, instead of the alkali treatment, easy-adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be applied 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.

(Liquid crystal display device)
In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates. However, the polarizing plate protective film of the present invention can provide excellent display properties regardless of where it is disposed. 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, the polarizing plate protective film is preferably used in this portion. The stretched polarizing plate protective film of the present invention is also preferably used as a retardation film for widening the viewing angle.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

"Evaluation methods"
First, the evaluation method will be summarized.

(1) Particle size of cellulose The weight average particle size of the obtained particles was measured by a flow particle image analyzer FPIA-2000 (manufactured by Toa Medical Electronics Co., Ltd.).

(2) Size of molded product The vertical, horizontal, and height of the molded product were measured, and the average value of 10 pieces was calculated. Molded products of 2 mm × 2 mm × 2 mm or less were measured with a scaled loupe (× 10).

(3) Maximum Dispersion Particle Size of Additive The obtained molded product was prepared by an OsO ₄ stained ultrathin section method, and observed with a transmission electron microscope (H-7100FA type manufactured by Hitachi). Moreover, the composition of the fine particles observed in the molded product was identified by the FESTEM-EDX method (field emission type, scanning transmission electron microscope; FESTEM; VG HB501).

From EDX analysis
Additive: Although the shape varies depending on the addition method, it was observed as acicular particles and spherical particles (from which P was detected). In Examples 7 and 9, no additive of 0.01 μm or more was observed, but P was detected at an arbitrary measurement position.

(4) Volume resistivity value About 0.8 g of dried cellulose acetate fine particles are placed in a commercially available tablet molding machine for infrared absorption spectrum measurement (circle with a molded internal cross section of 20 mm), and 400 kg / cm ² using a hydraulic press. To produce cylindrical pellets having a thickness of about 2 mm and both end faces of 20 mm in diameter in a dry N ₂ atmosphere. A main electrode having a diameter of 10 mm is applied and adhered to the center of both circular end faces of the pellet, and one end is grounded. Next, a guard electrode with one end grounded is provided along the outer periphery of the pellet, a DC voltage of 500 V is applied to the main electrode, and the current flowing between the main electrodes is directly read by an ammeter, and the current value at a stable stage The volume specific resistance value is calculated from the above. The measurement environment was a temperature of 23 ° C. and 50% RH, and the measurement was repeated 5 times, and the average value was taken as a measurement value.

(5) Dispersibility of additives in film The obtained film was prepared by an OsO ₄ dyed ultrathin section method, and observed with a transmission electron microscope (H-7100FA type manufactured by Hitachi). Moreover, the composition of the fine particles observed in the molded product was identified by the FESTEM-EDX method (field emission type, scanning transmission electron microscope; FESTEM; VG HB501).

From EDX analysis
Spherical particles and sea-island islands (from which P was detected) were observed.

  In some examples, an additive of 0.01 μm or more was not observed, but P was detected at an arbitrary measurement position in the film.

(6) Measurement of molecular weight The molecular weight of the obtained molding and film was measured by GPC (HLC-8220 manufactured by Tosoh Corporation).

Mwt; weight average molecular weight of the molded product Mwf; weight average molecular weight of the film Mwr; weight average molecular weight retention (%) = Mwf / Mwt × 100
(7) Measurement of elastic modulus The obtained film was cut out to a width of 5 mm, adjusted in humidity in an environmental test chamber adjusted to 23 ° C. and 70% Rh for 2 days, and then pulled using Toyo Baldwin's universal tensile tester STM T50BP. The elastic modulus was determined by measuring the stress at 0.5% elongation at a rate of 10% / min.

(8) pH and electric conductivity of cellulose ester resin 1 g of cellulose acetate propionate was added to 20 ml of pure water (electric conductivity 0.1 μS / cm, pH 6.8), and at 25 ° C. for 1 hr in a nitrogen atmosphere. After stirring, the pH and electrical conductivity were measured with a pH meter (HM-30V pH Meter: manufactured by TOA) and a conductivity meter (conductivity meter SC-51 type: manufactured by Yokogawa Hokushin Denki Co., Ltd.).

<< Material and Manufacturing Method >>
(Cellulose ester resin)
The cellulose ester resin in the examples is made from purified cotton linter or high-purity wood pulp as a raw material, and is produced by any of the widely known production methods called mixed acid method, methylene chloride method, and benzene method.

  The cellulose acetate propionate used in the examples was obtained by a mixed acid method, and passed through an esterification step, a hydrolysis step, a filtration step, a precipitation step, a water washing step, a dehydration step, a drying step, and a classification (fluid) step. It is manufactured. Since the present invention aims to obtain a film by heating and melting, it is necessary to pay particular attention to the washing step. This is because if even a small amount of the organic acid used in the production process remains, the decomposition of the cellulose ester resin may be promoted during heating and melting. Namely, 1 g of the obtained cellulose acetate propionate was put into 20 ml of pure water (electric conductivity 0.1 μS / cm, pH 6.8), and the pH when stirred at 25 ° C. for 1 hr in a nitrogen atmosphere. Is preferably 6 to 7 and the electrical conductivity is preferably 1 to 100 μS / cm. In the present invention, the cellulose acetate propionate obtained by the above production method was further washed with water (after-water washing). Thereafter, only four washing conditions were changed to prepare four types of cellulose acetate propionate. Cellulose acetate propionates 1 to 3 are obtained by changing the number of post-water washings. Cellulose acetate propionate 1, 2, and 3 were washed in the order of 0, 1, and 3 times. Cellulose acetate propionate 4 was prepared by washing cellulose acetate propionate 1 with a dilute alkaline aqueous solution (pH 8.0) and further washing with pure water once.

  In the post-water washing, 20 L of pure water was put into a 50 L lab pail, 1000 g of cellulose acetate propionate was added therein, stirred for 30 minutes, and then dehydrated with a centrifuge. The cellulose acetate propionate 1 to 4 was prepared by repeating this operation.

  The cellulose acetate propionate after the post-water washing and dehydration was placed in a constant temperature drier set at 50 ° C. and stirred moderately every 1 hr to perform 12 hr drying.

  The cellulose acetate propionate after drying was classified with a sieve shaker using a 30-mesh sieve (aperture 500 μm). When the particle size of the cellulose acetate propionate after classification was measured, the weight average particle size was 350 μm.

(Basic physical properties of cellulose acetate propionate used in the present invention)
Molecular weight; Mw 96000 Melting point; 225-235 ° C Tg; 170-180 ° C
Propyl substitution degree; 0.65 Acetic acid substitution degree; 1.95 Weight average particle diameter; 350 μm
(PH and electrical conductivity)
1g of cellulose acetate propionate after classification was put into 20ml of pure water (electric conductivity 0.1μS / cm, pH 6.8), stirred at 25 ° C, 1hr, nitrogen atmosphere, then pH and electric conductivity The degree was measured.

(Adjusting the particle size of cellulose acetate propionate)
The particle size of the cellulose acetate propionate used in the examples is adjusted by a dry pulverization method, an emulsification dispersion method, a spray drying method, or the like.

The dry pulverization method is performed using a jet mill, a hammer type cutter mill or the like. In the example, the desired number of times of pulverization was performed using a jet mill pulverizer (manufactured by Seishin Enterprise Co., Ltd.) under the conditions of a nozzle pressure of 0.7 MPa, an air volume of 1.1 m3 / min, and a throughput of 500 g / hr. Fine particles with a particle size were obtained. The obtained cellulose acetate propionate fine particles were dried under conditions of 90 ° C. and 5 hr (decompression degree: 1.33 × 10 ² Pa or less) while pulling a vacuum pump with a vacuum dryer (DP41 manufactured by Yamato).

In the emulsification dispersion method, 180 g of cellulose acetate propionate (weight average particle size 350 μm), 20 g of triphenyl phosphate as an organic additive, and 800 g of ethyl acetate are placed in a 3 L glass bottle, and mixed and dispersed for 3 hours with a stirrer to obtain uniform cellulose. An ester resin composition was obtained. Dissolve 100 g of sodium polyacrylate (manufactured by Wako Pure Chemical Industries, Ltd .; average polymerization degree n = 2700-7500, water content of about 80% by mass) as a dispersing agent, and dissolve 1 g of sodium alkyldiphenyl ether disulfonate in 1000 g of ion-exchanged water as a dispersing aid. A dispersion medium liquid was prepared. 1000 g of this aqueous medium is put in a 3 L round bottom stainless steel container, and the above resin composition is gradually added dropwise with stirring under the conditions described in Table 2 with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and 300 g is added for about 10 minutes. Over time. After completion of charging the resin composition, the mixture was further stirred for 10 minutes for emulsification. This operation was performed three times to emulsify 900 g of the resin composition. Thereafter, ethyl acetate is removed under the conditions of 50 to 55 ° C. and 1.33 × 10 ⁴ Pa to 3.99 × 10 ⁴ Pa, and after cooling, it is divided into three 5 L beakers, each having a total liquid volume of ² L. Thus, ion-exchanged water was additionally added and decantation was performed twice. Furthermore, stirring washing / filtration with 2 L of ion-exchanged water was repeated three times each at room temperature. The obtained cellulose ester fine particles were put in a constant temperature dryer set to 50 ° C., and stirred moderately every 1 hr, dried for 12 hr, and further, 90 ° C. while pulling a vacuum pump with a vacuum dryer (DP41 manufactured by Yamato). Drying was performed under conditions of 5 hr (decompression degree; 1.33 × 10 ² Pa or less).

(Adjusting the particle size of organic additives and dispersing and mixing with cellulose acetate propionate)
The particle size adjustment of the organic additive used in the examples and the dispersion mixing with the cellulose acetate propionate are adjusted by a dry method, an emulsification dispersion method, a spray adsorption method, or the like.

  The dry pulverization method is performed using a jet mill, a hammer type cutter mill, a Henschel mixer or the like. In the present invention, 100 g of triphenyl phosphate as an organic additive was crushed with a mortar in advance, and was then weighed using a vacuum dryer (DP41 manufactured by Yamato) under a condition of 30 ° C. × 5 hr while pulling a vacuum pump. Next, 100 g of a constant organic additive is added to 900 g of cellulose ester resin fine particles, and the mixture is stirred with a Henschel mixer under the conditions shown in Table 2 to adjust the particle size of the organic additive and mix with cellulose. It was.

  The emulsification dispersion method was performed as described in the particle size adjustment of the cellulose acetate propionate.

  In the spray adsorption method, 20 g of triphenyl phosphate as an organic additive was dissolved in 20 g of ethanol to obtain a 50 mass% additive ethanol solution. 180 g of cellulose acetate propionate was put into an open desktop mixer, and the additive ethanol solution was sprayed with a spray while stirring at 20 rpm to adjust the particle size of the organic additive and disperse and mix with cellulose.

(Molded product manufacturing method)
FIG. 1 shows an example of a jig for forming a molded product used in the example.

A stainless steel spacer having a mouth shape (thickness 5 to 50 mm) is placed on a stainless steel plate having a mirror surface property, and the resulting additive-containing cellulose ester resin fine particles are placed in a recess made of the spacer. After smoothing with a blade, a stainless steel plate having a predetermined thickness (10 mm to 25 mm) is fitted inside the mouth-shaped stainless steel spacer (recessed recess). Pressing is performed under the conditions of 25 ° C., 2.94 × 10 ⁷ Pa, and 10 minutes with a press machine to obtain a plate-like additive-containing cellulose ester resin molded product. In order to make the molded product have a desired thickness, the thickness of a jig such as a spacer is appropriately adjusted. Further, if necessary, the above-described operation is repeated several times to adjust the target thickness.

The obtained plate-shaped molded product was transferred to another stainless steel plate, and a die-cutting with a single side having many square ridges was placed on it (Fig. 1), and 4.9 × 10 ⁶ Pa was pressed under the conditions of 1 minute. As a result, a rectangular shaped product of the desired size was obtained.

  Molding temperature: It was carried out at a temperature at which cellulose does not deteriorate. Preferably it is below the glass transition temperature (Tg) of cellulose, More preferably, it is below Tg minus 50 degreeC. Since the temperature may rise during pressure molding, it is preferable to press while cooling. In the case of a material with significant deterioration, it is preferable to press at 0 ° C. or lower.

<Example 1>
(Adjusting the particle size of cellulose ester resin and additives)
As a cellulose ester resin, 1000 g of cellulose acetate propionate 3 shown in Table 1 is used in a jet mill grinder (manufactured by Seishin Enterprise Co., Ltd.) under the conditions of a nozzle pressure of 0.7 MPa, an air volume of 1.1 m ³ / min, and a throughput of 500 g / hr. Was then pulverized to obtain fine particles. The obtained cellulose ester resin fine particles were dried under conditions of 90 ° C. and 5 hr (pressure reduction: 1.33 × 10 ² Pa or less) while pulling a vacuum pump with a vacuum dryer (DP41 manufactured by Yamato).

100 g of triphenyl phosphate as an organic additive was pulled under a vacuum dryer (DP 41 manufactured by Yamato) with a vacuum pump (decompression degree: 1.33 × 10 ² Pa or less) at 30 ° C. × 5 hr. Quantified. Next, 100 g of triphenyl phosphate constanted to 900 g of cellulose ester resin fine particles was added, and the mixture was stirred with a Henschel mixer at 2000 rpm for 3 min to disperse the additive and mix with cellulose.

(Molded product manufacturing method)
A mouth-shaped stainless steel spacer (thickness 20 mm) is placed on a stainless steel plate having a mirror surface property shown in FIG. 1, and the resulting additive-containing cellulose ester resin fine particles are put into a recess made of the spacer. After smoothing with a blade, a stainless steel plate of a predetermined thickness (10 mm) is fitted inside the mouth-shaped stainless steel spacer (recessed recess). Pressing is performed under the conditions of 25 ° C., 2.9 × 10 ⁷ Pa, and 10 minutes with a press machine to obtain a plate-like additive-containing cellulose ester resin molding. The obtained plate-like molded product was transferred to another stainless steel plate, a die-cut with a sharp one-sided surface having many square ridges was placed, and pressure was applied at 4.9 × 10 ⁶ Pa for 1 minute. A square-shaped molding having the intended size shown was obtained.

(Film production method)
The obtained molding was subjected to T-die extrusion using a Haake PolyLab System single-screw extruder to obtain a film having a thickness of 80 to 90 μm.

T die: 0.5mm × 10cm
Temperature: temp1 200 ° C, temp2 210 ° C, temp3 220 ° C, die temp 230 ° C
(The larger the temp number is, the temperature of the extrusion part closer to the die. There are 4 blocks of heater parts including the die.)
Rotation speed: 100rpm
Residence time: 60 sec
Take-off speed: 350 ± 50 mm / sec (adjusted appropriately to obtain a desired film thickness)
The properties of the film obtained are listed in Table 3.

<Example 2>
(Adjusting the particle size of cellulose ester resin and additives)
The same procedure as in Example 1 was performed except that the number of passes in the jet mill was 1 and the condition of the Henschel mixer was 800 rpm × 3 min.

(Molded product manufacturing method)
The same procedure as in Example 1 was performed except that the thickness of the mouth-shaped stainless steel spacer, the thickness of the stainless steel plate fitted into the recess in the recess, and the pattern of the die cutting were changed to the conditions shown in Table 2.

(Film production method)
The same operation as in Example 1 was performed.

<Example 3>
(Adjusting the particle size of cellulose ester resin and additives)
The same procedure as in Example 1 was performed except that the number of passes in the jet mill was 3 times and the condition of the Henschel mixer was 3000 rpm × 3 min.

(Molded product manufacturing method)
The same operation as in Example 1 was performed.

(Film production method)
The same operation as in Example 1 was performed.

<Example 4>
(Adjusting the particle size of cellulose ester resin and additives)
As a cellulose ester resin, 1000 g of cellulose acetate propionate 3 was pulverized with a jet mill pulverizer (manufactured by Seishin Enterprise Co., Ltd.) under conditions of a nozzle pressure of 0.7 MPa, an air volume of 1.1 m ³ / min, and a throughput of 500 g / hr for 3 Pass. Fine particles were obtained. Next, 20 g of triphenyl phosphate as an additive was dissolved in 20 g of ethanol to obtain a 50 mass% additive ethanol solution. 180 g of cellulose ester resin fine particles were put into an open tabletop mixer, and the additive ethanol solution was sprayed by spraying while stirring at 20 rpm to disperse the additive and mix with cellulose. The obtained cellulose ester resin fine particles are put in a constant temperature dryer set at 50 ° C., and are stirred moderately every 1 hr, dried for 12 hr, and further, 90 ° C. while pulling a vacuum pump with a vacuum dryer (DP41 manufactured by Yamato). Drying was performed under conditions of 5 hr (decompression degree: 1.33 × 10 ² Pa or less).

(Molded product manufacturing method)
The same procedure as in Example 1 was performed except that the thickness of the mouth-shaped stainless steel spacer, the thickness of the stainless steel plate fitted into the recess in the recess, and the pattern of the die cutting were changed to the conditions shown in Table 2.

(Film production method)
The same operation as in Example 1 was performed.

<Example 5>
(Adjusting the particle size of cellulose ester resin and additives)
The same operation as in Example 4 was performed.

(Molded product manufacturing method)
The same operation as in Example 1 was performed.

(Film production method)
The same operation as in Example 1 was performed.

<Example 6>
(Adjusting the particle size of cellulose ester resin and additives)
The same procedure as in Example 1 was performed except that the cellulose ester resin was changed to cellulose acetate propionate 2.

(Molded product manufacturing method)
The same operation as in Example 1 was performed.

(Film production method)
The same operation as in Example 1 was performed.

<Example 7>
(Adjusting the particle size of cellulose ester resin and additives)
As a cellulose ester resin, 180 g of cellulose acetate propionate 2 and 20 g of triphenyl phosphate and 800 g of ethyl acetate as additives were placed in a 3 L glass bottle, and mixed and dispersed for 3 hours with a stirrer to obtain a uniform cellulose ester resin composition.

  Dissolve 100 g of sodium polyacrylate (manufactured by Wako Pure Chemical Industries, Ltd .; average polymerization degree n = 2700-7500, water content of about 80% by mass) as a dispersing agent, and dissolve 1 g of sodium alkyldiphenyl ether disulfonate in 1000 g of ion-exchanged water as a dispersing aid. A dispersion medium liquid was prepared. 1000 g of this aqueous medium is put into a 3 L round bottom stainless steel container, and the above resin composition is gradually added dropwise with stirring with TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at 12000 rpm × 10 min. And put it in. After completion of charging the resin composition, the mixture was further stirred for 10 minutes for emulsification. This operation was performed three times to emulsify 900 g of the resin composition.

Thereafter, ethyl acetate is removed under the conditions of 50 to 55 ° C. and 1.33 × 10 ⁴ Pa to 3.99 × 10 ⁴ Pa, and after cooling, it is divided into three 5 L beakers, each having a total liquid volume of ² L. Thus, ion-exchanged water was additionally added and decantation was performed twice. Furthermore, stirring washing / filtration with 2 L of ion-exchanged water was repeated three times each at room temperature. The obtained cellulose ester resin fine particles were dried under the conditions described in Table 2 with a vacuum dryer (DP41 manufactured by Yamato).

(Molded product manufacturing method)
The same operation as in Example 1 was performed.

(Film production method)
The same operation as in Example 1 was performed.

<Example 8>
(Adjusting the particle size of cellulose ester resin and additives)
Cellulose acetate propionate 3 was used without being pulverized by a jet mill, and the same procedure as in Example 1 was performed except that the conditions of the Henschel mixer were changed to 500 rpm × 3 min.
(Molded product manufacturing method)
The same operation as in Example 1 was performed.

(Film production method)
The same operation as in Example 1 was performed.

<Example 9>
The same procedure as in Example 7 was performed except that the conditions for stirring with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) were 16000 rpm × 30 min.

<Example 10>
The same procedure as in Example 1 was performed except that the cellulose ester resin was changed to cellulose acetate propionate 1.

<Example 11>
The same procedure as in Example 1 was performed except that the cellulose ester resin was changed to cellulose acetate propionate 4.

<Example 12>
The same procedure as in Example 3 was performed except that the conditions of the Henschel mixer were changed to 800 rpm × 3 min.

<Example 13>
(Adjusting the particle size of cellulose ester resin and additives)
As a cellulose ester resin, 1000 g of cellulose acetate propionate 3 described in Table 1 above was used with a jet mill grinder (manufactured by Seishin Enterprise Co., Ltd.), nozzle pressure 0.7 MPa, air volume 1.1 m ³ / min, throughput 500 g / hr. These conditions were pulverized by 3 Pass to obtain fine particles. The obtained cellulose ester resin fine particles were dried under conditions of 70 ° C. and 2 hr (decompression degree: 1.33 × 10 ² Pa or less) while pulling a vacuum pump with a vacuum dryer (DP41 manufactured by Yamato).

(Organic additives)
Plasticizer: 100 g of triphenyl phosphate (DP41 manufactured by yamato) pulling a vacuum pump (decompression degree: 1.33 × 10 ² Pa or less), and constanting at 30 ° C. × 5 hr. .)
Antioxidant; Tinuvin 144 (Ciba Specialty Chemicals) 5g
UV absorber; LA-31 (Asahi Denka Kogyo Co., Ltd.) 12g
(Inorganic additive)
Sliding material; R972V (made by Nippon Aerosil Co., Ltd.) 3g
The organic additive and the inorganic additive were added to 880 g of cellulose ester resin fine particles, and the mixture was stirred with a Henschel mixer at 3000 rpm for 3 minutes to disperse the additive and mix with cellulose.

(Molded product manufacturing method)
The same procedure as in Example 1 was performed except that the thickness of the mouth-shaped stainless steel spacer, the thickness of the stainless steel plate fitted into the recess in the recess, and the pattern of the die cutting were changed to the conditions shown in Table 2. The obtained molded product was injected with N ₂ gas having a dew point of −40 ° C. from a purge port while pulling a vacuum pump with a vacuum dryer (DP 41 manufactured by Yamato), and at 130 ° C. for 3 hours under a dry N ₂ atmosphere. Drying was performed under the conditions. When the moisture content of the molded product after drying was measured by a coulometric titration method using a Karl Fischer moisture measurement device (manufactured by Dia Instruments), it was 90 ppm.

(Film production method)
The same operation as in Example 1 was performed.

<Example 14>
(Adjusting the particle size of cellulose ester resin and additives)
The same operation as in Example 13 was performed.

(Molded product manufacturing method)
The same procedure as in Example 1 was performed except that the thickness of the mouth-shaped stainless steel spacer, the thickness of the stainless steel plate fitted into the recess in the recess, and the pattern of the die cutting were changed to the conditions shown in Table 2. The obtained molded product was injected with N ₂ gas having a dew point of −40 ° C. from a purge port while pulling a vacuum pump with a vacuum dryer (DP 41 manufactured by Yamato), and at 130 ° C. for 3 hours under a dry N ₂ atmosphere. Drying was performed under the conditions. It was 120 ppm when the moisture content of the molded product after drying was measured by a coulometric titration method using a Karl Fischer moisture content measurement device (manufactured by Dia Instruments).

(Film production method)
The same operation as in Example 1 was performed.

<Comparative example 1>
(Adjusting the particle size of cellulose ester resin and additives)
The same operation as in Example 1 was performed.

(Molded product manufacturing method)
The same procedure as in Example 1 was performed except that the thickness of the mouth-shaped stainless steel spacer, the thickness of the stainless steel plate fitted into the recess in the recess, and the pattern of the die cutting were changed to the conditions shown in Table 2.

(Film production method)
Although it carried out similarly to Example 1, the molded product, ie, supply, was not stable at the inlet, and an evaluable film could not be obtained.

<Comparative example 2>
(Adjusting the particle size of cellulose ester resin and additives)
The same operation as in Example 1 was performed.

(Molded product manufacturing method)
The same procedure as in Example 1 was performed except that the thickness of the mouth-shaped stainless steel spacer, the thickness of the stainless steel plate fitted into the recess in the recess, and the pattern of the die cutting were changed to the conditions shown in Table 2.

(Film production method)
Although it carried out similarly to Example 1, since the molding produced blocking at the inlet and the machine was forcibly stopped due to excessive load, an evaluable film could not be obtained.

  In addition, the schematic diagram of the TEM observation of the cellulose ester resin shape | molded in the Example and the comparative example and the organic type additive was shown in FIG.

  The above molded product and cellulose ester film were evaluated according to the above evaluation methods, and the results are shown in Tables 2 and 3.

  From the above table, the examples according to the present invention have a good dispersibility of the organic additives in the film as compared with the comparative examples, and the cellulose ester has a high weight average molecular weight retention rate during the preparation of the heat-melted film. It can be seen that the deterioration of the resin is suppressed, and therefore the elastic modulus of the film is also excellent.

It is an example of the jig | tool which forms the molding used for the Example. It is a schematic diagram of TEM observation of a molded article cross section.

Claims (8)

In the method for producing a polarizing plate protective film obtained by mixing at least a cellulose ester resin and an organic additive to obtain an integral molded product and then melting by heating, the size of the molded product is 1 mm × 1 mm × 1 mm The manufacturing method of the polarizing plate protective film characterized by being in the range of -20 mm x 20 mm x 20 mm cube, and containing the cellulose ester resin in the molded product in a particle state. The organic additive in the molded product contains a maximum dispersed particle size (eDmax) of 100 μm or less, and the weight average particle size (cDw50) of the cellulose ester resin in the particle state and the maximum dispersed particle size (eDmax) are It has the following relationship, The manufacturing method of the polarizing plate protective film of Claim 1 characterized by the above-mentioned.
cDw50> eDmax The method for producing a polarizing plate protective film according to claim 1 or 2, wherein the cellulose ester resin has a weight average particle size (cDw50) in the range of 1 to 200 µm. The maximum dispersion particle diameter in the polarizing plate protective film of the said organic type additive is 0.1 micrometer or less, The manufacturing method of the polarizing plate protective film of any one of Claims 1-3 characterized by the above-mentioned. 1 g of the cellulose ester resin was added to 20 ml of pure water (electric conductivity 1 μS / cm or less, pH 6.8) and stirred at 25 ° C. for 1 hr in a nitrogen atmosphere. 5. The method for producing a polarizing plate protective film according to any one of claims 1 to 4, wherein the degree is 1 to 100 [mu] S / cm. The method for producing a polarizing plate protective film according to claim 1, wherein the cellulose ester resin has a volume resistivity of 10 ¹¹ to 10 ¹⁵ Ω · cm. The molecular weight retention ratio Mwr (%) = Mwf / Mwt × 100, when the weight average molecular weight of the molded product is Mwt and the weight average molecular weight of the obtained film is Mwf, is 85 to 100%. The manufacturing method of the polarizing plate protective film of any one of claim | item 1 -6. A polarizing plate protective film produced by the method for producing a polarizing plate protective film according to claim 1.

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