JP2006330087A - Hydrolysate of metal alkoxide, method of preparing solution of the hydrolysate, method of manufacturing optical film using the hydrolysate, optical film and polarizing plate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrolysate of metal alkoxide used for manufacturing an optical film which is used as a protective film for a polarizing plate etc. of a liquid crystal display device (LCD), to provide a method of preparing a solution of the hydrolysate, to provide an optical film which is obtained by using the hydrolysate of metal alkoxide, has excellent dimensional characteristics, has high film strength and has improved toughness , to provide a manufacturing method of the optical film and to provide a polarizing plate which is excellent in dimensional stability and moreover permits the improvement of the quality (dimensional stability) of an LCD by using the optical film. <P>SOLUTION: In the preparation of a cellulose ester film as the optical film, a dope of the cellulose ester film is prepared by mixing an organic solvent, the hydrolysate of metal alkoxide and cellulose ester, wherein, when preparing the hydrolysate of the metal alkoxide, a dope main solvent which dissolves cellulose ester is added as a part of reaction solvent and, thereby, hydrolysis of metal alkoxide is performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrolyzate of metal alkoxide used for the production of an optical film, a method for producing the hydrolyzate solution, a method for producing an optical film using the hydrolyzate, an optical film, and a polarizing plate using the same It is about.

  In the present invention, the optical film means various functional films such as a protective film for a polarizing plate used for a liquid crystal display (LCD), a retardation film, a viewing angle widening film, an antireflection film used for a plasma display, or an organic film. It means various functional films used in EL displays and the like.

  In recent years, liquid crystal display devices (LCDs) are space-saving and energy-saving, so the use of liquid crystal displays for TVs, personal computers, mobile phones and the like is increasing. Based on such an increase in demand for LCDs, the supply of LCDs is also increasing, and with the increase in production of optical films, film quality such as film surface properties is becoming important.

  In particular, with the progress of larger screens and higher image quality of TVs, and the expansion, generalization, and diversification of usage locations, liquid crystal displays are required to have higher quality, and display functions and visual recognition functions are further improved. Is required.

  Cellulose ester films are mainly used as protective films for LCD polarizing plates, but the visibility of liquid crystal display devices (LCDs) is related to the stability of display displays and polarizing plates (time, heat, toughness). In particular, dimensional stability is required. For this, the dimensional stability of the optical film becomes important.

  Although dimensional stabilization of optical films has been studied in the past, higher dimensional stability is required due to the large screen of liquid crystal display devices (LCD), usage patterns, and diversification of usage environments. .

  As described above, cellulose triacetate films are generally widely used for polarizing plate protective films, but conventional cellulose triacetate films lack dimensional stability (particularly dimensional stability at high temperatures). I found out.

In order to solve the above-mentioned problems, a film obtained by adding a crosslinking compound (hydrolyzable metal alkoxide) to cellulose ester and finally promoting crosslinking is polymerized, for example, in the following Patent Documents 1 and 2 Proposed.
Patent Document 1 discloses an optical film made of a cellulose acetate film. In Patent Document 1, cellulose acylate is a compound that generates an acid by light by a solution casting method. A cellulose acylate film is produced by a process including a casting process of casting a cellulose acylate composition containing a hydroxyaryl group-containing oligomer and a compound that crosslinks with an acid, and a light irradiation process. Yes. Japanese Patent Application Laid-Open No. 2004-148811 discloses an optical film made of a cellulose acylate film. In Patent Document 2, a radical polymerizable compound having a cellulose acylate and a cyclic structure aliphatic hydrocarbon group is disclosed. A cellulose acylate film is produced by a series of steps including a casting step of casting a cellulose acylate composition containing a monomer and a photopolymerization initiator, and a light irradiation step.

  However, in the methods described in Patent Documents 1 and 2, in any case, since the polymer is crosslinked by light irradiation in the steps after the casting step, variation in the polymerization degree of the polymer occurs due to variation in light irradiation, There are problems such as precipitation of foreign matter due to light irradiation, there is a problem that sufficient light energy cannot be given, and the dimensional stability of the film is not sufficiently good.

  The object of the present invention is to solve the above-mentioned problems of the prior art and to provide a hydrolyzate of metal alkoxide and a hydrolyzate solution of the metal alkoxide used for the production of an optical film used as a protective film for a liquid crystal display element, that is, a polarizing plate. A method for producing the same, an optical film having excellent dimensional characteristics, high film strength, and improved toughness using a hydrolyzate of metal alkoxide, and a method for producing the same, and a method for producing the optical film. It is an object of the present invention to provide a polarizing plate that is excellent in dimensional stability and can improve the quality (dimensional stability) of a liquid crystal display (LCD).

  As a result of intensive studies in view of the above points, the present inventor has obtained a hydrolyzate of metal alkoxide when producing a dope (resin solution) of a cellulose ester film as an optical film containing a hydrolyzate of metal alkoxide. It was found that the hydrolyzate can be stabilized by adding a dope main solvent (such as methylene chloride) that dissolves cellulose ester as a part of the reaction solvent and hydrolyzing the metal alkoxide.

  In order to achieve the above object, the invention of the hydrolyzate of metal alkoxide used in the production of the optical film according to claim 1 is a cellulose ester film as an optical film containing at least one hydrolyzate of metal alkoxide. In preparing the dope for the cellulose alkoxide by mixing the organic solvent, metal alkoxide hydrolyzate and cellulose ester, the dope main solvent that dissolves the cellulose ester when preparing the metal alkoxide hydrolyzate As a part of the reaction solvent, the metal alkoxide is hydrolyzed.

  The invention of claim 2 is the hydrolyzate of the metal alkoxide according to claim 1, wherein the use ratio of the cellulose ester dope main solvent to the total solvent used in the hydrolysis reaction of the metal alkoxide is 0% by weight. It is characterized by being over 70 wt%.

  The invention of claim 3 is the hydrolyzate of metal alkoxide according to claim 1 or 2, wherein the cellulose ester dope main solvent is methylene chloride.

  Invention of Claim 4 is a hydrolyzate of the metal alkoxide as described in any one of Claims 1-3, Comprising: A metal alkoxide is a silica alkoxide, It is characterized by the above-mentioned.

  The invention of claim 5 is a method for producing a hydrolyzate solution of a metal alkoxide used for the production of an optical film, wherein a cellulose ester film is produced as an optical film containing at least one hydrolyzate of a metal alkoxide. In preparing the hydrolyzate of metal alkoxide when mixing the organic solvent, hydrolyzate of metal alkoxide, and cellulose ester to prepare the dope of the cellulose ester film, react the dope main solvent that dissolves the cellulose ester. In addition to being part of the solvent, the metal alkoxide is hydrolyzed.

  Invention of Claim 6 is a manufacturing method of the hydrolyzate solution of the metal alkoxide of Claim 5, Comprising: The use ratio of the cellulose ester dope main solvent with respect to all the use solvents at the time of hydrolyzing a metal alkoxide is used. , More than 0% by weight and 70% by weight or less.

  The invention of claim 7 is a method for producing a hydrolyzate solution of metal alkoxide according to claim 5 or 6, wherein the cellulose ester dope main solvent is methylene chloride.

  The invention of claim 8 is the method for producing a hydrolyzate solution of metal alkoxide according to any one of claims 5 to 7, wherein the metal alkoxide is silica alkoxide.

  Invention of Claim 9 is a manufacturing method of the optical film using the hydrolyzate of metal alkoxide, Comprising: The hydrolyzate of metal alkoxide as described in any one of Claims 1-4, the organic solvent, Cellulose ester is mixed to produce a dope of the cellulose ester film, and the dope of the cellulose ester film is cast on a metal support by a solution casting film forming method to produce an optical film made of the cellulose ester film. It is characterized by doing.

  The invention of claim 10 is the method for producing an optical film according to claim 9, wherein the dope of the cellulose ester film is mixed with a hydrolyzate of metal alkoxide, an organic solvent, and a cellulose ester, and then the mixed solution is 30. It is characterized in that it is produced by standing still or stirring at a rotational speed of 60 rpm or less for minutes to 72 hours.

  Invention of Claim 11 is a manufacturing method of the optical film of Claim 9 or 10, Comprising: Dope of a cellulose-ester film is made from the hydrolyzate of a metal alkoxide, an organic solvent, a cellulose ester, a plasticizer, and / or ultraviolet rays. It is characterized by being prepared by mixing an absorbent.

  The invention of an optical film of claim 12 is characterized by being manufactured by the manufacturing method according to any one of claims 9 to 11.

  The invention of the polarizing plate of claim 13 is that the optical film of claim 12 constitutes at least one of two polarizing plate protective films arranged on both sides of the polarizing film. It is a feature.

  The invention of the hydrolyzate of metal alkoxide used in the production of the optical film according to claim 1 is directed to producing a cellulose ester film as an optical film containing at least one hydrolyzate of metal alkoxide. When preparing a hydrolyzate of metal alkoxide when preparing a cellulose ester film dope by mixing the hydrolyzate and cellulose ester, the main solvent for dissolving the cellulose ester is added as a part of the reaction solvent. The metal alkoxide is hydrolyzed. According to the present invention, a main solvent for doping (such as methylene chloride) is mixed with the reaction solvent in the hydrolysis reaction of the metal alkoxide. , A hydrolyzate of metal alkoxide produced by hydrolysis reaction Since the polymerization reaction is suppressed and each molecule of the metal alkoxide hydrolyzate can be stably present in a dispersed state, stable pseudo-crosslinking can be performed between the metal alkoxide hydrolyzate and the cellulose ester, and an optical film It is possible to improve the strength and toughness of the optical film, contribute to the dimensional stability of the optical film, and further improve the dimensional stability of the polarizing plate using the optical film, This in turn has the effect of being effective in the dimensional stability of the display panel of the liquid crystal display device (LCD).

  The invention according to claim 2 is the hydrolyzate of the metal alkoxide according to claim 1, wherein the use ratio of the cellulose ester dope main solvent to the total solvent used in the hydrolysis reaction of the metal alkoxide is 0% by weight. If the ratio of the cellulose ester dope main solvent to the total solvent used in the hydrolysis reaction of the metal alkoxide is within this range, the hydrolysis reaction of the metal alkoxide is less than 70% by weight. Since the further polymerization reaction of the hydrolyzate of the metal alkoxide produced in step 1 is suppressed and each molecule of the hydrolyzate of the metal alkoxide can be stably present in a dispersed state, the hydrolysis of the metal alkoxide when mixed with the cellulose ester Stable pseudo-crosslinking between the product and cellulose ester improves the strength of the optical film and toughness It is possible to perform the improvement of an effect that can contribute to the dimensional stability of the optical film.

  The invention of claim 3 is a hydrolyzate of the metal alkoxide according to claim 1 or 2, wherein the cellulose ester dope main solvent is methylene chloride. According to the present invention, the hydrolysis of the metal alkoxide is performed. In the reaction, by mixing methylene chloride, which is the main solvent for the dope, into the reaction solvent, further polymerization reaction of the hydrolyzate of the metal alkoxide generated by the hydrolysis reaction of the metal alkoxide is suppressed, and the metal alkoxide hydrolyzate is stabilized. There is an effect.

  Invention of Claim 4 is a hydrolyzate of the metal alkoxide as described in any one of Claims 1-3, Comprising: A metal alkoxide is a silica alkoxide, Especially among metal alkoxides, By using silica alkoxide, since the dope main solvent (such as methylene chloride) is mixed with the reaction solvent in the hydrolysis reaction of silica alkoxide, further polymerization of the hydrolyzed silica alkoxide produced by the hydrolysis reaction is suppressed. Since each molecule of the silica alkoxide hydrolyzate can stably exist in a dispersed state, when mixed with the cellulose ester, stable pseudo-crosslinking can be performed between the cellulose ester and the silica alkoxide hydrolyzate, and the optical film Optical film can improve strength and toughness An effect that can contribute to the dimensional stability.

  Invention of the hydrolyzate solution of the metal alkoxide used for manufacture of the optical film of Claim 5 is organic in producing the cellulose ester film as an optical film containing the hydrolyzate of at least one metal alkoxide. When preparing a hydrolyzate of a metal alkoxide when mixing a solvent, a hydrolyzate of metal alkoxide, and a cellulose ester to prepare a dope of a cellulose ester film, a dope main solvent that dissolves the cellulose ester is used as a reaction solvent. According to the present invention, the metal alkoxide hydrolyzate is stabilized by mixing the dope main solvent with the reaction solvent in the hydrolysis reaction of the metal alkoxide. That is, when preparing a hydrolyzate of metal alkoxide, the dope main solvent is mixed with the reaction solvent in the hydrolysis reaction of metal alkoxide. Therefore, the presence of this dope main solvent causes the metal alkoxide produced in the hydrolysis reaction to be mixed. Since the further polymerization reaction of the hydrolyzate is suppressed and each molecule of the metal alkoxide hydrolyzate can be stably present in a dispersed state, a stable pseudo-crosslinking between the metal alkoxide hydrolyzate and the cellulose ester is achieved. It is possible to improve the strength and toughness of the optical film and contribute to the dimensional stability of the optical film.

  Invention of Claim 6 is a manufacturing method of the hydrolyzate solution of the metal alkoxide of Claim 5, Comprising: The use ratio of the cellulose ester dope main solvent with respect to all the use solvents at the time of hydrolyzing a metal alkoxide is used. If the use ratio of the cellulose ester dope main solvent to the total solvent used in the hydrolysis reaction of the metal alkoxide is within this range, it is more than 0% by weight and 70% by weight or less. Further polymerization reaction of metal alkoxide hydrolyzate generated by hydrolysis reaction is suppressed, and each molecule of metal alkoxide hydrolyzate can exist stably in a dispersed state. Therefore, when cellulose ester is mixed, metal alkoxide Stable pseudo-crosslinking between the hydrolyzate and cellulose ester is possible, and the strength of the optical film is improved. An effect that is.

  The invention of claim 7 is a method for producing a hydrolyzate solution of a metal alkoxide according to claim 5 or 6, wherein the cellulose ester dope main solvent is methylene chloride. In the alkoxide hydrolysis reaction, by mixing methylene chloride, which is the dope main solvent, into the reaction solvent, further polymerization reaction of the metal alkoxide hydrolyzate generated in the metal alkoxide hydrolysis reaction is suppressed, and metal alkoxide hydrolysis is performed. There is an effect that the physical solution is stabilized.

  The invention of claim 8 is a method for producing a hydrolyzate solution of a metal alkoxide according to any one of claims 5 to 7, wherein the metal alkoxide is a silica alkoxide, and the metal alkoxide Among them, by using silica alkoxide in particular, since the dope main solvent (such as methylene chloride) is mixed with the reaction solvent in the hydrolysis reaction of silica alkoxide, the silica alkoxide hydrolyzate generated by the hydrolysis reaction is further increased. Since polymerization is suppressed and each molecule of the silica alkoxide hydrolyzate can be stably present in a dispersed state, stable pseudo-crosslinking can be achieved between the cellulose ester and the silica alkoxide hydrolyzate when mixed with the cellulose ester. In addition to improving the strength and toughness of optical films An effect that can contribute to the dimensional stability of the optical film.

  Invention of Claim 9 is a manufacturing method of the optical film using the hydrolyzate of metal alkoxide, Comprising: The hydrolyzate of metal alkoxide as described in any one of Claims 1-4, the organic solvent, Cellulose ester is mixed to produce a dope of the cellulose ester film, and the dope of the cellulose ester film is cast on a metal support by a solution casting film forming method to produce an optical film made of the cellulose ester film. Therefore, according to the present invention, since a dope main solvent (such as methylene chloride) is mixed with the reaction solvent in the hydrolysis reaction of the metal alkoxide, it is generated by the hydrolysis reaction due to the presence of this dope main solvent. Further polymerization reaction of metal alkoxide hydrolyzate is suppressed and each molecule of metal alkoxide hydrolyzate is scattered Because it can exist stably, stable pseudo-crosslinking can be achieved between the hydrolyzate of metal alkoxide and cellulose ester, which can improve the strength and toughness of the optical film and improve the dimensional stability of the optical film. The effect that it can contribute is produced.

  Invention of Claim 10 is a manufacturing method of the optical film of Claim 9, Comprising: After mixing the hydrolyzate of metal alkoxide, the organic solvent, and the cellulose ester especially, the liquid mixture is 30 minutes-72 hours. In the meantime, by standing or stirring at a rotational speed of 60 rpm or less, the metal alkoxide hydrolyzate is stably present in a dispersed state, and the metal alkoxide hydrolyzate and cellulose ester Pseudo-crosslinking between the two is promoted, and more stable pseudo-crosslinking can be achieved.

  Invention of Claim 11 is a manufacturing method of the optical film of Claim 9 or 10, Comprising: Dope of a cellulose-ester film is made from the hydrolyzate of a metal alkoxide, an organic solvent, a cellulose ester, a plasticizer, and / or ultraviolet rays. Made by mixing an absorbent, pseudo-crosslinking that occurs between the metal alkoxide hydrolyzate and the cellulose ester even if a plasticizer and / or UV absorber is included with the metal alkoxide hydrolyzate Therefore, stable pseudo-crosslinking between the hydrolyzate of the metal alkoxide and the cellulose ester can be achieved, and the strength and toughness of the optical film can be improved, and the dimensional stability of the optical film can be improved. There is an effect that it can contribute.

  Since the invention of the optical film of claim 12 is produced by the method of producing an optical film according to any one of claims 9 to 11, the optical film is excellent in dimensional stability, There is an effect of having excellent film strength and toughness.

  Moreover, according to the optical film of this invention, in addition to the above, it became clear that the retardation stability (humidity fluctuation tolerance, temperature fluctuation tolerance) of an optical film also improved.

  The invention of the polarizing plate of claim 13 is that the optical film of claim 12 constitutes at least one of two polarizing plate protective films disposed on both sides of the polarizing film. The dimensional stability of the polarizing plate can be improved, and as a result, the dimensional stability of the display panel of the liquid crystal display device (LCD) can be improved.

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

  First, the present invention relates to a hydrolyzate of a metal alkoxide used in the production of an optical film that can be used particularly as a protective film for a polarizing plate of a liquid crystal display device (LCD).

  The hydrolyzate of the metal alkoxide used for the production of the optical film according to the present invention is a hydrolysis of an organic solvent, a metal alkoxide in producing a cellulose ester film as an optical film containing at least one metal alkoxide hydrolyzate. When a metal alkoxide hydrolyzate is produced by mixing the product and cellulose ester to produce a dope of the cellulose ester film, a dope main solvent that dissolves the cellulose ester is added as a part of the reaction solvent, and the metal alkoxide is added. Hydrolysis.

  In the present invention, the substrate (polymer compound) of the optical film is preferably a cellulose ester.

  Here, as a cellulose ester which is the main raw material of a cellulose ester film, cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, cellulose acetate propionate, etc. are mentioned. In the case of cellulose triacetate, cellulose triacetate having a polymerization degree of 250 to 400 and a bound acetic acid amount of 54 to 62.5% is preferable, and a cellulose triacetate having a bound acetic acid amount of 58 to 62.5% has a strong base strength. More preferred. As the cellulose triacetate, either cellulose triacetate synthesized from cotton linter or cellulose triacetate synthesized from wood pulp can be used alone or in combination.

  In the case of the solution casting film forming method, it is preferable to use a large amount of cellulose triacetate synthesized from a cotton linter that is excellent in releasability from a support made of a driving rotating metal endless belt or drum, because of high productivity efficiency.

  In the case of producing a cellulose ester film, the ratio of cellulose triacetate synthesized from cotton linter is 60% by weight or more, and since the effect of peelability becomes significant, 60% by weight or more is preferable, more preferably 85% by weight or more, Furthermore, it is most preferable to use it alone.

  In the present invention, in preparing a cellulose ester film as an optical film containing a hydrolyzate of at least one metal alkoxide, an organic solvent, a hydrolyzate of metal alkoxide, and a cellulose ester are mixed to obtain a cellulose ester film. A dope is produced.

  In the production of the cellulose ester film by the solution casting film forming method, it is necessary to evaporate the organic solvent (solvent) after casting the dope. Therefore, it is preferable to use a volatile organic solvent. Furthermore, the organic solvent does not react with a metal alkoxide, a catalyst, or the like, and does not dissolve the casting base material. Two or more organic solvents may be mixed and used.

  Here, an organic solvent (organic solvent) having good solubility with respect to the cellulose ester is referred to as a good solvent, and has a main effect on dissolution, and the organic solvent used in a large amount among them is a main solvent or a main solvent. That's it.

  Examples of good solvents include ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethers such as tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane, 1,2-dimethoxyethane, formic acid Esters such as methyl, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, methyl cellosolve, dimethylimidazolinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethyl sulfoxide, sulfolane, nitroethane, methylene chloride And 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and methylene chloride are preferable.

  In addition to the organic solvent, the cellulose ester dope preferably contains 1 to 40% by weight of an alcohol having 1 to 4 carbon atoms. After casting the dope of cellulose ester on a metal support, the solvent starts to evaporate and the ratio of alcohol increases, so that the web (dope film) is gelled, the web becomes strong, and the metal support It is used as a gelling solvent that makes it easy to peel from, and when these ratios are small, it also has the role of promoting the dissolution of cellulose esters of non-chlorine organic solvents, There is also a role to suppress an increase in viscosity.

  Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, and propylene glycol monomethyl ether. Of these, ethanol is preferred because it is excellent in stability of the cellulose ester dope, has a relatively low boiling point, good drying properties, and is not toxic. These organic solvents alone are not soluble in cellulose esters and are called poor solvents.

  As a ratio of the most preferable solvent as a solvent for dissolving cellulose ester, which is a preferable polymer compound satisfying such conditions, at a high concentration, for example, methylene chloride is preferably 70 to 95% by weight, and other solvents are preferably 30 to 5% by weight. . The cellulose ester concentration is preferably 10 to 50% by weight. The heating temperature with the addition of the solvent is preferably a temperature not lower than the boiling point of the solvent used and in a range where the solvent does not boil, for example, preferably 60 ° C. or higher and 80 to 110 ° C. The pressure is determined so that the solvent does not boil at the set temperature.

  Next, the metal alkoxide used in the present invention will be described.

  In the present invention, regarding the metal alkoxide, the metal means “periodic table chemistry” by Iwanami Shoten, Kazuo Saito, p. 71. A metal according to 71, that is, a metal containing a metalloid atom.

  The metal alkoxide used in the present invention is preferably at least one metal selected from the group consisting of silicon (Si), titanium (Ti), zirconium (Zr) and aluminum (Al). Particularly preferred is silicon (Si).

  Such a metal alkoxide is ideal when the central metal is M, the number of atoms is q, the non-hydrolyzed substituent is A, the number of substituents is p, the hydrolyzable substituent is B, and the number of substituents is r. Specifically, the hydrolysis reaction is completed as in the following formula (1), and a metal oxide is obtained.

Equation _{(1) A p M q B} r → A p M q O r / 2
The content of the metal oxide can be obtained as the content of the metal oxide in the ash after burning the film material containing the metal alkoxide.

  In the present invention, the content of the metal oxide is defined as Gm as the weight of the metal oxide contained in the residue after burning the film containing the hydrolyzate of metal alkoxide to 500 ° C., and the weight of the film before combustion. When Gf, it is expressed by the following formula (2).

Formula (2) Gm / Gf x100
The weight of the metal oxide can be measured by ICP-AES analysis (inductively coupled plasma emission spectroscopy) using SPS-4000 manufactured by Seiko Denshi Kogyo Co., Ltd. At this time, when a component other than the metal oxide (such as phosphorus) is contained in the ash, the amount of the metal oxide in the ash can be measured by a known method.

  As content of the inorganic substance of the film material containing the hydrolyzate of metal alkoxide, 0.1 to 40 weight% is preferable with respect to the total weight of a film. More preferably, it is 0.5-20 weight%, More preferably, it is 0.5-5 weight%.

  Here, when the addition amount of the inorganic substance is less than 0.1% by weight, the effect of improving the physical properties of the film containing the hydrolyzate of metal alkoxide is not recognized, and when it exceeds 40% by weight, the hydrolyzate of metal alkoxide is included. This is because the film becomes brittle.

  The measurement of the average particle diameter of the hydrolyzate in the optical film according to the present invention can be obtained by transmission electron microscope observation and X-ray small angle scattering measurement. Preferred is a method obtained by X-ray small angle scattering measurement.

  For details of the X-ray small angle scattering method, for example, the X-ray diffraction handbook 3rd edition (issued by Rigaku Corporation in 2000) can be referred to. As is well known, if there are regions with different electron densities in the sample, diffuse scattering is observed in the incident X-ray direction. Since this scattering is observed in a scattering angle range of about 0 to 5 °, these scatterings are called small-angle scattering.

  For this scattering curve, the average particle size of the hydrolyzate is measured using the Guinier plot or the Fankuchen method.

  The preferable average particle diameter of the hydrolyzate in the optical film containing the hydrolyzate of the metal alkoxide of the present invention is 1 to 200 nm. More preferably, it is 1-100 nm, More preferably, it is 1-50 nm, and 1-20 nm is the most preferable.

  The hydrolyzate of metal alkoxide used in the present invention is less likely to form aggregates and stabilizes the state of small particle size compared to the conventional method of adding metal oxide fine particles dispersed in a cellulose ester solution. It is excellent in that it is obtained.

As the metal alkoxide, the above formula (1)
A _p M _q B _r
In the above, it is preferable that all of them are substituted with a hydrolyzable substituent such that p = 0, but from the viewpoint of reducing the moisture permeability of the base film, the metal 1 atom is added by a non-hydrolyzed substituent. One, two, or three substituted compounds may be included.

  The amount of the metal alkoxide having a substituent that is not hydrolyzed is preferably 50 mol% or less of the metal alkoxide to be added. Moreover, you may use together 2 or more types of different types of metal alkoxide in the range of the said addition amount.

  As such a non-hydrolyzed substituent, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group is preferable. As the substituent of the alkyl group or aryl group, an alkyl group (for example, a methyl group, an ethyl group) is preferable. Etc.), cycloalkyl groups (eg cyclopentyl group, cyclohexyl group etc.), aralkyl groups (eg benzyl group, 2-phenethyl group etc.), aryl groups (eg phenyl group, naphthyl group etc.), heterocyclic groups (eg furan, thiophene) , Pyridine etc.), alkoxy groups (eg methoxy group, ethoxy group etc.), aryloxy groups (eg phenoxy group etc.), acyl groups, halogen atoms, cyano groups, amino groups, alkylthio groups, glycidyl groups, vinyl groups, fluorine atoms A containing alkyl group or a fluorine atom-containing aryl group.

  As the metal alkoxide used in the present invention, as a silicon compound, for example, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetra-t-butoxysilane, tetrakis (methoxyethoxy) silane, Tetrakis (methoxypropoxy) silane, tetrachlorosilane, tetraisocyanate silane and the like can be mentioned.

  Examples of silicon compounds having substituent groups that are not hydrolyzed include dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldiisopropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldiisopropoxysilane, and diethyldibutoxy. Silane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldiisopropoxysilane, diphenyldibutoxysilane, 3-glycidoxypropylmethyldimethoxysilane, dichlorodimethylsilane, dichlorodiethylsilane, methyltrimethoxysilane, methyltriethoxysilane, Methyltriisopropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropyl Poxysilane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltributoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, 3 -Glycidoxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, (3 -Acryloxypropyl) trimethoxysilane, acetoxytriethoxysilane, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane, (3,3,3- (Trifluoropropyl) trimethoxysilane, methyltrichlorosilane, ethyltrichlorosilane, phenyltrichlorosilane, (3,3,3-trifluoropropyl) triethoxysilane, pentafluorophenylpropyltrimethoxysilane, (heptadecafluoro-1,1 , 2,2-Tetrahydrodecyl) triethoxysilane, (3,3,3-trifluoropropyl) trichlorosilane, pentafluorophenylpropyltrichlorosilane, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) trichlorosilane Methyl triisocyanate silane, phenyl triisocyanate silane, vinyl triisocyanate silane, and the like.

  In addition, quantified silicon compounds such as silicate 40, silicate 45, silicate 48, and M silicate 51 manufactured by Tama Chemical, which are partially condensed with these compounds, may be used.

  In the present invention, when preparing a hydrolyzate of metal alkoxide, the ratio of the cellulose ester dope main solvent to the total solvent used when performing the hydrolysis reaction of the metal alkoxide exceeds 0% by weight and 70% by weight. Hereinafter, it is preferably more than 5% by weight and 65% by weight or less.

  Thus, in the hydrolysis reaction of the metal alkoxide, the dope main solvent (for example, methylene chloride) is mixed with the reaction solvent at a predetermined ratio, thereby further polymerizing the metal alkoxide hydrolyzate generated by the hydrolysis reaction. Stable pseudo-crosslinking between metal alkoxide hydrolyzate and cellulose ester when mixed with cellulose ester dope, because it can be stably present in a dispersed state with each molecule of metal alkoxide hydrolyzate It is something that can be done. Moreover, when mixing the dope of a cellulose ester with the hydrolyzate of a metal alkoxide, there also exists an advantage that a cellulose ester does not precipitate from a dope.

  Here, the pseudo-crosslinking between the metal alkoxide hydrolyzate and the cellulose ester means that the OH group in the cellulose ester and the metal alkoxide hydrolyzate are pseudo-crosslinked by a weak interaction such as a hydrogen bond. It is thought that the state is possible.

  In addition, when producing the hydrolyzate of metal alkoxide, it is preferable that the hydrolysis reaction of all the metal alkoxides is completed, but unreacted metal alkoxide may remain after the hydrolysis reaction. That is, the completion of the hydrolysis reaction of the metal alkoxide may be performed in the hydrolysis solution, in the cellulose ester dope, or in the cellulose ester film.

  In the method for producing a hydrolyzate solution of metal alkoxide of the present invention, when the metal alkoxide is hydrolyzed by adding a dope main solvent that dissolves cellulose ester as a part of the reaction solvent, water and A catalyst may be added to promote the hydrolysis reaction.

  However, from the viewpoint of productivity such as film haze, flatness, film forming speed, solvent recycling, etc., the water content may be in the range of 0.01 wt% to 2.0 wt% in the cellulose ester dope. preferable.

  In addition, when water is added to the hydrophobic metal alkoxide, an alcohol solvent such as methanol, ethanol, methyl cellosolve is added to the total amount of the solvent so that the metal alkoxide and water are easily mixed. % Or less may be added.

  As the catalyst for promoting the hydrolysis of the metal alkoxide, inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, organic acids such as acetic acid, trifluoroacetic acid, levulinic acid, citric acid, p-toluenesulfonic acid and methanesulfonic acid are used. . After the acid is added and the sol-gel reaction proceeds, the base may be added for neutralization. When adding a base and neutralizing, it is preferable that content of the alkali metal before a drying process is less than 5000 ppm (here, an alkali metal includes an ionic state thing). In addition, Lewis acids such as acetates of metals such as germanium, titanium, aluminum, antimony and tin, other organic acid salts, halides and phosphates may be used in combination.

  Further, as a catalyst, instead of such acids, ammonia, monoethanolamine, diethanolamine, triethanolamine, diethylamine, triethylamine and the like, bicyclo such as DBU (diazabicycloundecene-1) and DBN (diazabicyclononene) are used. Bases such as ring amine, ammonia, phosphine, alkali metal alkoxide, ammonium hydroxide, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide can be used.

  The amount of the acid or alkali catalyst added is not particularly limited, but is preferably 1.0 to 20% by weight based on the amount of the metal alkoxide. Moreover, you may perform the process of an acid and a base in multiple times. After performing the necessary hydrolysis, the catalyst may be neutralized, the volatile catalyst may be removed under reduced pressure, or it may be removed by liquid separation washing or the like.

  The reaction state of hydrolysis of the metal alkoxide can be confirmed by infrared absorption spectrum and NMR.

  When silica alkoxide is used as the metal alkoxide, when the silica alkoxide or organoalkoxysilane is hydrolyzed, the OR group is replaced with OH, and further, a reaction occurs that condenses with other Si-OH or Si-OR. In the case of, Si-OR, Si-OH, Si-OR (condensation polymer), and corresponding peaks appear. A corresponding peak appears in the 29-Si-NMR spectrum.

  In the optical film containing the hydrolyzate of metal alkoxide in the present invention, a plasticizer for imparting processability, flexibility and moisture resistance to the film, fine particles (matting agent) for imparting slipperiness to the film, and an ultraviolet absorbing function. It may contain an ultraviolet absorber, an antioxidant that prevents deterioration of the film, a retardation adjusting agent that adjusts the retardation of the film, and the like.

  The plasticizer used in the present invention is not particularly limited, but it may be generated by hydrogen bonds or the like with a hydrolyzate of cellulose ester or metal alkoxide so as not to generate haze, bleed out or volatilize from the film. It preferably has a functional group capable of interacting.

  Examples of such functional groups include hydroxyl groups, ether groups, carbonyl groups, ester groups, carboxylic acid residues, amino groups, imino groups, amide groups, imide groups, cyano groups, nitro groups, sulfonyl groups, sulfonic acid residues, Examples thereof include a phosphonyl group and a phosphonic acid residue, and a carbonyl group, an ester group and a phosphonyl group are preferred.

  Examples of such plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol ester plasticizers, glycolate plasticizers. Agents, citric acid ester plasticizers, fatty acid ester plasticizers, carboxylic acid ester plasticizers, polyester plasticizers, etc. can be preferably used, but polyhydric alcohol ester plasticizers, glycolate plasticizers are particularly preferred. And non-phosphate ester plasticizers such as polycarboxylic acid ester plasticizers.

  For example, examples of the phosphate ester include triphenyl phosphate, tricresyl phosphate, phenyl diphenyl phosphate, and the like. Examples of carboxylic acid esters include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, and diethyl hexyl phthalate. Mention may be made of tributyl. In addition, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin, and the like are also included. Alkyl phthalyl alkyl glycolates are also preferably used. The alkyl in the alkylphthalylalkyl glycolate is an alkyl group having 1 to 8 carbon atoms. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate, Ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, propyl phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl Phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl Collate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl glycolate and the like can be mentioned, such as methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, Octyl phthalyl octyl glycolate is preferable, and ethyl phthalyl ethyl glycolate is particularly preferably used. A plasticizer having a large molecular weight is preferable because it can suppress volatilization during extrusion. Examples of these include aliphatic polyesters composed of glycol and dibasic acids such as polyethylene adipate, polybutylene adipate, polyethylene succinate and polybutylene succinate, and fats composed of oxycarboxylic acids such as polylactic acid and polyglycolic acid. Aliphatic polyesters composed of lactones such as aromatic polyesters, polycaprolactone, polypropiolactone and polyvalerolactone, and vinyl polymers such as polyvinylpyrrolidone. These plasticizers can be used alone or in combination.

  The polyhydric alcohol ester is composed of an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  The polyhydric alcohol used in the present invention is represented by the following general formula (3).

Formula _{(3) R 1 - (OH} ) n
(Wherein R ₁ represents an n-valent organic group, and n represents a positive integer of 2 or more)
Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these.

  Examples of preferred polyhydric alcohols include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, gallium Examples include lactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

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

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

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, Tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, laccellic acid, etc., undecylen Examples thereof include unsaturated fatty acids such as acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

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

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. Examples thereof include aromatic monocarboxylic acids and derivatives thereof, and benzoic acid is particularly preferable.

  The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester.

  The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  These plasticizers can be used alone or in combination of two or more.

  It is preferable to contain 1-30 weight% of content of the plasticizer mentioned above with respect to a cellulose ester. By containing the plasticizer in this range, the dimensional stability of the cellulose ester film under wet heat can be improved. If the amount of plasticizer used is less than 1% by weight relative to the cellulose ester, the effect of reducing the moisture permeability of the film is small, which is not preferred. If it exceeds 30% by weight, the plasticizer bleeds out from the film. Since the physical properties of the film deteriorate, it is not preferable.

  In the present invention, fine particles may be added in order to impart film slipperiness. The fine particles used in the present invention may be either inorganic fine particles or organic fine particles.

  In the present invention, organic fine particles are preferably used in order to reduce the difference in refractive index from the resin. As the organic fine particles, for example, polymers such as silicone resin, fluorine resin, and acrylic resin are preferable, and among them, silicone resin and acrylic resin are preferably used.

  Among the above-described silicone resins, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120 and 240 (manufactured by Toshiba Silicone Co., Ltd.) Commercial products having a trade name such as can be used. Cross-linked PMMA particles are also preferably used. For example, commercial products having trade names such as MX-150, 300, 500, 1000, 1500H (manufactured by Soken Chemical Co., Ltd.) can be used.

  Further, in the present invention, it is preferable to use fine particles having a refractive index difference of 0.04 or less from the resin because a film having a high transparency and a low transparency can be obtained. Examples of such fine particles include an E-poster MA having a refractive index of 1.49, an E-poster GP having a refractive index of 1.52 (manufactured by Nippon Shokubai Co., Ltd.), and a techpolymer made by Sekisui Plastics Co., Ltd. with an adjustable refractive index. This can be achieved by combining the MSX series and the like with a resin.

  On the other hand, inorganic fine particles include silicon-containing compounds, silicon dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and Calcium phosphate and the like are preferable, and inorganic fine particles containing silicon and zirconium oxide are more preferable. Among them, silicon dioxide is particularly preferably used because the turbidity of the cellulose ester laminated film can be reduced. As specific examples of silicon dioxide, commercially available products having trade names such as Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be preferably used. .

  In the present invention, as the fine particles of zirconium oxide, for example, those commercially available under trade names such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.

  In the present invention, the film-to-slip property can be imparted by setting the particle diameter of the fine particles in the film to an equivalent circle diameter of 0.05 to 5.0 μm. When the fine particles used in the present invention are monodisperse particles, the average particle size of the fine particles in the powder becomes the average particle size in the film, so the above range can be selected by selecting the average particle size of the added fine particles. Can be achieved. When the particle size is less than 0.05 μm, the projection height from the film is low, and the films stick to each other and cause deformation. If it exceeds 5.0 μm, even if the refractive index difference between the resin and the fine particles is small, the haze increase cannot be suppressed and the transparency of the film is impaired, which is not preferable as a liquid crystal member.

  The content of the fine particles in the film is preferably 0.05 to 0.5% by weight in order to provide slipperiness between the films. When the content is less than 0.05% by weight, the number of projections from the film is small, and the films stick to each other and cause deformation. If it exceeds 0.5% by weight, an increase in haze cannot be suppressed even if the refractive index difference between the resin and the fine particles is small, and the transparency of the film is impaired.

  The optical film according to the present invention contains an ultraviolet absorber for protecting the liquid crystal material. That is, the optical film according to the present invention contains a liquid ultraviolet absorber at 25 ° C. The liquid ultraviolet absorber is a so-called liquid ultraviolet absorber at normal temperature. Here, “liquid at normal temperature” means a liquid that does not have a certain shape, is fluid, and has a substantially constant volume, as defined in “Chemical Encyclopedia (1963) Kyoritsu Publishing” at 25 ° C. Show. Therefore, the melting point is not limited as long as it has the above properties, but a compound having a melting point of 30 ° C. or lower, particularly preferably 15 ° C. or lower is preferable.

  The liquid ultraviolet absorber may be a single compound or a mixture, and a mixture composed of a group of structural isomers can be preferably used as the mixture.

  As the ultraviolet absorber, those having excellent absorption ability of ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of a polarizer or liquid crystal and those having little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. preferable.

  Specific examples of useful UV absorbers in the present invention 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'-hydroxy) 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-5 A mixture of-(5-chloro-2H-benzotriazol-2-yl) phenyl] propionate can be mentioned, but is not limited thereto.

  Moreover, as a commercial item of the ultraviolet absorber, TINUVIN 109, TINUVIN 171 and TINUVIN 326 (all manufactured by Ciba Specialty Chemicals) can be preferably used.

  Specific examples of the benzophenone compounds that are ultraviolet absorbers that can be used in the present invention include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5- Examples thereof include, but are not limited to, sulfobenzophenone and bis (2-methoxy-4-hydroxy-5-benzoylphenylmethane).

  In this invention, the compounding quantity of these ultraviolet absorbers has the preferable range of 0.01-10 weight% with respect to a cellulose ester, Furthermore, 0.1-5 weight% is preferable. If the amount of the ultraviolet absorber used is too small, the ultraviolet absorbing effect may be insufficient. If the amount of the ultraviolet absorber is too large, the transparency of the film may be deteriorated. The ultraviolet absorber preferably has high heat stability.

  The amount of the ultraviolet absorber preferably used in the present invention is 0.1 to 5% by weight, preferably 0.3 to 3% by weight, more preferably 0.1% by weight to the cellulose ester from the viewpoint of ultraviolet absorption effect and transparency. Is 0.5 to 2% by weight.

  When the substitution degree of the acetyl group of the cellulose ester is low, the heat resistance may be lowered. In this case, it is effective to add an antioxidant.

  Although the antioxidant which can be used for the optical film containing the hydrolyzate of the metal alkoxide of the present invention is generally referred to as a deterioration preventing agent, it is preferably contained in the optical film. That is, when a liquid crystal display device or the like is placed in a high humidity and high temperature state, the optical film may be deteriorated. The antioxidant has a role of delaying or preventing the film from being decomposed by, for example, halogen in the residual solvent in the film or phosphoric acid of the phosphoric acid plasticizer, so that it is preferably contained in the film. .

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t A phosphorus-based processing stabilizer such as -butylphenyl) phosphite may be used in combination.

  The amount of these compounds added is preferably 1 ppm to 1.0% by weight, more preferably 10 to 1000 ppm, by weight with respect to the cellulose ester.

  Next, the present invention relates to a method for producing an optical film using a hydrolyzate of metal alkoxide, and an optical film containing a hydrolyzate of metal alkoxide according to the present invention can be produced by a solution casting film forming method. .

  As described above, the invention of the hydrolyzate of metal alkoxide used in the production of the optical film according to the present invention is organic in producing a cellulose ester film as an optical film containing at least one hydrolyzate of metal alkoxide. When preparing a hydrolyzate of a metal alkoxide when mixing a solvent, a hydrolyzate of metal alkoxide, and a cellulose ester to prepare a dope of a cellulose ester film, a dope main solvent that dissolves the cellulose ester is used as a reaction solvent. In addition to this, the metal alkoxide is hydrolyzed.

  Specifically, when a dope is prepared by mixing an organic solvent, a hydrolyzate of metal alkoxide, and a cellulose ester, the main solvent of the cellulose ester dope is used as at least a part of the reaction solvent in the metal alkoxide charging pot. A metal alkoxide hydrolysis reaction is performed to produce a metal alkoxide hydrolyzate.

  When preparing the metal alkoxide hydrolyzate, the reaction solvent for performing the hydrolysis reaction of the metal alkoxide exceeds the main solvent of the cellulose ester dope by more than 0% by weight and not more than 70% by weight, preferably 5 to 67% by weight, It is preferable to contain in the ratio of 10 to 65 weight% or less.

  Furthermore, when a catalyst, water, or the like is added to the metal alkoxide, an alcohol-based solvent such as methanol, ethanol, or methyl cellosolve is added to 50% of the total solvent amount so that the metal alkoxide can be easily mixed. You may add in the following ratios.

  Then, the metal alkoxide hydrolyzate solution is guided to a filter, the metal alkoxide hydrolyzate solution is filtered by the filter to remove aggregates, and then the metal alkoxide hydrolyzate solution is filtered. And the following cellulose ester dope are mixed.

  In the present invention, in order to produce a dope for a cellulose ester film, an organic solvent (organic solvent) mainly composed of a good solvent for cellulose ester (flaked) is absorbed in the dissolution vessel with the cellulose ester, a plasticizer, and an ultraviolet absorber. Additives such as plasticizers are dissolved with stirring, or additives such as plasticizers and UV absorbers are pre-dissolved in a solution of cellulose ester in which cellulose ester is dissolved in an organic solvent mainly composed of a good solvent. The dope is formed by mixing the additive solution.

  Various dissolution methods for dissolving the cellulose ester, such as a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed under pressure above the boiling point of the main solvent, a method performed by the cooling dissolution method, a method performed at high pressure, etc. However, a method in which the pressure is applied above the boiling point of the main solvent is particularly preferable.

  The temperature at this time is preferably from the boiling point of the solvent to less than 80 ° C. The concentration of the cellulose ester in the dope is preferably 10 to 35% by weight.

  Next, mixing of the hydrolyzate of metal alkoxide and the cellulose ester dope will be described.

  In the present invention, a hydrolyzate of a metal alkoxide is prepared by using a cellulose ester-doped main solvent as at least a part of a reaction solvent for hydrolysis of a metal alkoxide, and the hydrolyzate of the metal alkoxide and cellulose An optical film dope is prepared by mixing with an ester dope.

  In this invention, the compounding quantity of the hydrolyzate of the metal alkoxide with respect to a cellulose ester dope is 0.3-7.0 weight in conversion of the silicic acid which a metal alkoxide produces | generates as a result of a hydrolysis with respect to 100 weight part of cellulose esters. Part, preferably 0.5 to 5.0 parts by weight of a metal alkoxide hydrolyzate is added.

  In the present invention, the metal alkoxide hydrolyzate and cellulose ester dope produced in separate kettles may be mixed after filtration. In this case, the cellulose ester dope is preferably mixed little by little while slowly stirring the hydrolyzate of the metal alkoxide.

  According to the hydrolyzate of the metal alkoxide of the present invention, the metal alkoxide hydrolyzate is stabilized by mixing the dope main solvent (methylene chloride) with the reaction solvent in the hydrolysis reaction of the metal alkoxide. That is, when preparing a hydrolyzate of a metal alkoxide, a dope main solvent (such as methylene chloride) is previously mixed with the reaction solvent in the hydrolysis reaction of the metal alkoxide. The further polymerization reaction of the hydrolyzate of the metal alkoxide produced by the decomposition reaction is suppressed, and each molecule of the hydrolyzate of the metal alkoxide can be stably present in a scattered state, so that the hydrolyzate of the metal alkoxide and the cellulose ester Stable pseudo-crosslinking can be achieved between the two.

  Thus, according to the present invention, the pseudo-crosslinking reaction of the hydrolyzate of the metal alkoxide has already occurred at the time of dope adjustment, and most of the completed state of the pseudo-crosslinking of the optical film is determined at this point.

  In the present invention, the prepared metal alkoxide hydrolyzate and the cellulose ester dope are mixed, and then the mixed solution is allowed to stand for 30 minutes to 72 hours, or stirred at a rotational speed of 60 rpm or less with a stirring blade, for example. Therefore, it is preferable to make it stagnant. Thus, by maintaining the mixed state of the metal alkoxide hydrolyzate and the cellulose ester dope for a certain period, the pseudo-crosslinking reaction between the cellulose ester and the metal alkoxide hydrolyzate is promoted, and thus the dimensions of the optical film. Stability can be ensured.

  In the method for producing an optical film using a hydrolyzate of metal alkoxide according to the present invention, a dope of a cellulose ester film is mixed with a hydrolyzate of metal alkoxide, an organic solvent, a cellulose ester, a plasticizer and / or an ultraviolet absorber. May be produced. Thus, even if a plasticizer and / or an ultraviolet absorber is contained together with the hydrolyzate of the metal alkoxide, it does not hinder the pseudo-crosslinking that occurs between the hydrolyzate of the metal alkoxide and the cellulose ester. Further, stable pseudo-crosslinking between the hydrolyzate of metal alkoxide and the cellulose ester can be performed, and the strength and toughness of the optical film can be improved, and the dimensional stability of the optical film can be contributed.

  Here, the additive solution of the plasticizer and / or ultraviolet absorber may be added directly to the solution of the cellulose ester dope charging vessel, or the plasticizer and / or ultraviolet ray prepared in the additive solution dissolving vessel. After the absorbent additive solution is filtered, the plasticizer and / or ultraviolet absorber additive solution may be introduced before the static mixer and added in-line to the cellulose ester dope.

  The addition of fine particles to the cellulose ester dope may be directly added as a powder to the solution of the cellulose ester dope or after the fine particle additive solution is prepared by dispersing in a solvent in the additive solution dissolving vessel. Although it may be added to the solution in the dope charging kettle, it is preferable to add it in advance in a solvent or the like in order to suppress the formation of aggregates and the like.

  The fine particle additive solution prepared in the additive solution dissolution vessel is filtered through a filter and then introduced into the solution in the dope charging vessel and added to the cellulose ester dope when dissolved or added in-line to the cellulose ester dope.

  Then, the cellulose ester dope containing a plasticizer, an ultraviolet absorber, and fine particles is introduced into a filter and filtered. In the filter, the cellulose ester dope is filtered with a filter medium such as filter paper or a sintered metal filter.

  After producing the dope of the cellulose ester film, it is taken out from the container while being cooled, or extracted from the container with a pump or the like and cooled with a heat exchanger or the like, and used for film formation.

  The invention of the method for producing an optical film according to the present invention uses a metal alkoxide hydrolyzate solution produced by the above-described method for producing a metal alkoxide hydrolyzate, and uses the solution casting film forming method described below to perform casting. A cellulose-ester film can be obtained through a process.

  In the casting process of the solution casting film forming method, a dope of a cellulose ester film as an optical film containing a hydrolyzate of a metal alkoxide is fed to a pressure die through a liquid feeding pump such as a pressure type quantitative gear pump. The dope is cast from a pressure die slit to a casting position on a metal support such as an endless metal belt that moves infinitely, such as a stainless steel belt or a rotating metal drum.

  For casting the dope, a pressure die that can adjust the slit shape of the die portion of the casting die and easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used.

  The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is preferable to obtain the film containing the hydrolyzate of the metal alkoxide of a laminated structure by the co-casting method which casts several dope simultaneously.

  The web (dope film) is heated with a metal support, and the solvent is evaporated until the web becomes peelable from the metal support.

  For evaporating the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the metal support by a liquid, a method of transferring heat from the front and back by radiant heat, etc. However, drying efficiency is good and preferable. A method in which the above methods are combined is also preferable. In the case of the backside liquid heat transfer method, the heating is preferably performed at a temperature equal to or lower than the boiling point of the main solvent of the organic solvent used in the dope or the organic solvent having the lowest boiling point.

  The web (film) from which the solvent has evaporated on the metal support is peeled off by a peeling roll at the peeling position. The peeled web is sent to the next process. If the residual solvent amount of the web at the time of peeling (the following formula) is too large, peeling is difficult, or conversely, if the web is peeled off after being sufficiently dried on the metal support, The part may come off.

  Here, as a method for increasing the film forming speed (the film forming speed can be increased by peeling while the residual solvent amount is as large as possible), there is a gel casting method (gel casting). For example, there are a method in which a poor solvent for cellulose ester is added to the dope and the gel is formed after casting the dope, a method in which the temperature of the metal support is lowered and gelled. By making it gel on the metal support and increasing the strength of the film at the time of peeling, the peeling can be accelerated and the film forming speed can be increased.

  In the present invention, by forming a pseudo cross-linked state in the dope state, the film strength becomes strong and peeling becomes easy, so that the film forming speed can be increased.

  Depending on the strength of the web drying conditions on the metal support, the length of the metal support, etc., it is preferable to peel the web in the range of the residual solvent amount of the web of 5 to 150% by weight. When peeling at many points, if the web is too soft, the flatness at the time of peeling will be damaged, and slipping and vertical stripes due to peeling tension will tend to occur.Therefore, the balance of economic speed and film quality will balance the residual solvent at the time of peeling the web. The amount is decided.

  In the present invention, the temperature at the peeling position on the metal support is preferably -50 to 40 ° C, more preferably 10 to 40 ° C, and most preferably 15 to 30 ° C.

  The residual solvent amount of the web at the peeling position on the metal support is preferably 10 to 150% by weight, more preferably 10 to 120% by weight.

  The residual solvent amount can be expressed by the following formula.

Residual solvent amount (% by weight) = {(M−N) / N} × 100
Here, M is the weight of the web at any point in time, and N is the weight when a weight M is dried at 110 ° C. for 3 hours.

  After peeling, the web is dried using a tenter device that grips and conveys the web with clips or pins and / or a drying device that alternately conveys the web through rolls arranged in the drying device. .

  In this invention, it is preferable to extend | stretch 1.0-2.0 times with respect to the width direction, and it is preferable to extend | stretch using a tenter apparatus. More preferably, it is biaxially stretched in the longitudinal and transverse directions. The draw ratio is set according to the target optical characteristics (in-plane direction retardation Ro, thickness direction retardation Rt). Moreover, when manufacturing retardation film, it can also be uniaxially stretched in the elongate direction.

  The optical film of the present invention can provide a film having an in-plane retardation (Ro) of 0 to 1000 nm and a thickness direction retardation (Rt) of 0 to 500 nm.

  By adding the cellulose ester dope to the hydrolyzate solution of metal alkoxide, the retardation values Ro and Rt per film thickness of the stretched film can be increased. Even under high-temperature and high-humidity conditions, the retardation values Ro and Rt do not fluctuate and the durability is excellent, and a thinner film can be provided.

  As a drying means, hot air is generally blown on both sides of the web, but there is also a means for heating by applying a microwave instead of the wind. Excessively rapid drying is not preferable because the flatness of the finished film tends to be impaired. Throughout, the web drying temperature is usually in the range of 40-250 ° C. The drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, and the drying conditions may be appropriately selected according to the type and combination of the solvents used.

  When the residual solvent amount in the web (film) becomes 2% by weight or less, it is wound up as a cellulose ester film. By setting the residual solvent amount to 0.4% by weight or less, a film having good dimensional stability can be obtained.

  As a winding method, a generally used method may be used. There are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

  To adjust the film thickness, it is necessary to control the dope concentration, the pumping amount of the pump, the slit gap of the die base, the extrusion pressure of the die, the speed of the casting support, etc. so as to obtain the desired thickness. Good.

  The thickness of the optical film produced by the method of the present invention is 20 to 150 [mu] m, and it is preferably 30 to 100 [mu] m from the viewpoint of reducing the thickness and weight of the liquid crystal display device. If the thickness of the optical film is less than 20 μm, the stiffness of the film is reduced, so that troubles due to wrinkles are likely to occur in the polarizing plate manufacturing process, and the thickness of the optical film is 150 μm. If the thickness is greater than 1, the contribution to thinning of the liquid crystal display device is small. The film thickness of the optical film can be adjusted by controlling the extrusion flow rate, the slit gap of the die base, the speed of the rotationally driven endless belt or the cooling drum, etc. so as to obtain a desired thickness. Further, as a means for making the film thickness uniform, it is preferable that the film thickness detection means is used to feed back the programmed feedback information to each of the above devices and adjust it.

  The optical film of the present invention preferably has a width of 1 to 4 m. According to the present invention, since an optical film excellent in dimensional stability is obtained, a remarkable effect is recognized with a wide cellulose ester film. In particular, a film width of 1.4 to 4 m is preferably used, and a film width of 1.4 to 2 m is particularly preferable. When the film width exceeds 4 m, the conveyance becomes difficult.

  In the present invention, before winding the film, the end of the film is slit and trimmed to the product width, and knurling (embossing) is applied to both ends of the film to prevent scratches and scratches during film winding. Apply to the department. In the knurling method, a metal ring having uneven pattern on the side surface can be processed by heating and / or pressing.

In the optical film according to the present invention, the relationship between the knurling height a (μm) and the film thickness d (μm) is such that the ratio X (%) of the knurling height a (μm) to the film thickness d (μm) is X ( %) = (A / d) × 100
The ratio X is preferably in the range of 2 to 25%.

  Here, when the ratio a / d between the knurling height (a) and the film thickness (d) is less than 2%, the films stick to each other, the film is deformed, or the surface is damaged. No. On the other hand, if the ratio a / d exceeds 25%, a dent in the central portion of the width becomes large when wound with a long length, which also causes winding deformation and deformation of the film, which is not preferable.

  The method for producing an optical film using the metal alkoxide hydrolyzate solution of the present invention comprises mixing the above metal alkoxide hydrolyzate solution, an organic solvent, and a cellulose ester to produce a dope of the cellulose ester film, A cellulose ester film dope is cast on a metal support by a solution casting film forming method to produce an optical film made of a cellulose ester film. In the hydrolysis reaction of a metal alkoxide, the main solvent is a dope. By mixing a solvent (such as methylene chloride), the presence of this dope main solvent suppresses further polymerization reaction of the hydrolyzate of the metal alkoxide produced by the hydrolysis reaction, and each molecule of the hydrolyzate of the metal alkoxide. Can exist stably in a dispersed state, so that the hydrolyzate of metal alkoxide and cellulose Can stable pseudo crosslinking between Suesuteru, strength of the optical film improves, it is possible to perform the improvement of the toughness, can contribute to the dimensional stability of the optical film.

  Furthermore, according to the optical film of the present invention, in addition to the above, it has been found that the retardation stability (humidity fluctuation resistance, temperature fluctuation resistance) of the optical film is also improved.

  The optical film according to the present invention manufactured as described above is a protective film for a polarizing plate used for a liquid crystal display device (LCD) or the like, a retardation film, a viewing angle widening film, an antireflection film used for a plasma display, etc. It can also be used for various functional films and various functional films used in organic EL displays.

  Next, the polarizing plate according to the present invention can be produced by bonding the optical film to at least one surface of a polarizing film (polarizing film).

  That is, the polarizing plate according to the present invention is a polarizing plate comprising a polarizing film and two polarizing plate protective films disposed on both sides thereof, and at least one of the two polarizing plate protective films is The optical film according to the present invention is configured as described above.

  In addition, the optical film by this invention may be bonded together to the other surface of a polarizing film, and another protective film for polarizing plates may be bonded together.

  A polarizing film, which is the main component of a polarizing plate, is an element that allows only light with a polarization plane in a certain direction to pass through. A typical polarizing film currently known can be stretched and oriented, such as a polyvinyl alcohol film. This film was processed with a dichroic dye such as iodine and stretched longitudinally. Since the polarizing film itself does not have sufficient strength and durability, a polarizing plate is generally obtained by adhering a cellulose triacetate film having no anisotropy as a protective film to both sides thereof.

  A method for attaching the optical film to the polarizing film is not particularly limited, but can be performed with an adhesive made of an aqueous solution of a water-soluble polymer. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution.

  Furthermore, a long polarizing plate can be obtained by laminating a long polarizing film which has been stretched in the longitudinal direction and treated with a dichroic dye and a long optical film of the present invention. A polarizing plate is a sticking type in which a peelable sheet is laminated on one or both sides thereof via a pressure-sensitive adhesive layer (for example, an acrylic pressure-sensitive adhesive layer). It can be easily attached to a cell or the like.

  According to the polarizing plate of the present invention, the dimensional stability of the polarizing plate can be improved, and as a result, the dimensional stability of the display panel of a liquid crystal display device (LCD) can be improved.

  The polarizing plate of the present invention can be used for various display devices. In particular, a liquid crystal display device using a VA mode liquid crystal molecule in which liquid crystal molecules are substantially vertically aligned when no voltage is applied, or a TN mode liquid crystal cell in which liquid crystal molecules are substantially horizontal and twisted when no voltage is applied. Is preferred.

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

Examples 1-3
In producing a cellulose triacetate film as an optical film having a target dry film thickness of 40 μm by a solution casting film forming method, a hydrolyzate of silica alkoxide was first prepared.

<Preparation of hydrolyzate of metal alkoxide>
Tetraethoxysilane (silica alkoxide) 48.4 parts by weight Amberlyst 15 dry (catalyst, manufactured by Organo) 9.5 parts by weight Ethanol 48.4 parts by weight Methylene chloride 89.9 parts by weight Water (added last) 8.4 parts by weight Part First, the above materials were mixed in a metal alkoxide charging kettle at room temperature and stirred for 12 hours to prepare a hydrolyzate of metal alkoxide. Here, as a reaction solvent for tetraethoxysilane (silica alkoxide), 65% by weight of methylene chloride, which is a main solvent for cellulose triacetate dope, was used.

(Dope composition)
100 parts by weight of cellulose triacetate having an acetyl substitution degree of 2.88 (number average molecular weight: 150,000)
UV-23L (ultraviolet absorber) 0.75 parts by weight UV-28L (ultraviolet absorber) 0.75 parts by weight AEROSIL 200V 0.1 part by weight Triphenyl phosphate 10 parts by weight Ethylphthalyl ethyl glycolate 2 parts by weight Methylene chloride 475 parts by weight Ethanol 25 parts by weight A dope having the above composition was prepared. First, a hydrolyzate of silica alkoxide was put into a dope melting pot, and then a solvent was added. Next, a plasticizer and an ultraviolet absorber were added to the dope dissolution vessel containing the hydrolyzate of silica alkoxide and a solvent with stirring. While stirring, this was completely dissolved, and further, cellulose triacetate was added and heated to dissolve.

  At this time, the amount of silica alkoxide hydrolyzate is 100 parts by weight of cellulose triacetate so that the silica alkoxide is 0.5 parts by weight in terms of silicic acid produced as a result of hydrolysis. Cellulose triacetate was added to a solution containing a hydrolyzate, a plasticizer, and an ultraviolet absorber.

  Thereafter, the cellulose triacetate dope containing a plasticizer, an ultraviolet absorber, and a hydrolyzate of silica alkoxide was filtered. The dope after filtration was stirred in a dope stock kettle for 24 hours with a stirring blade at a rotation speed of 30 rpm, and was kept stationary.

  In Examples 2 and 3, the dope constituent material was added in the same order as in Example 1, but in Example 2, the amount of hydrolyzate of silica alkoxide was 100 parts by weight of cellulose triacetate. On the other hand, in Example 3, the amount of the hydrolyzate of silica alkoxide is 100 parts by weight of cellulose triacetate so that silica alkoxide gives 2.0 parts by weight in terms of silicic acid produced as a result of hydrolysis. On the other hand, the hydrolyzate of silica alkoxide was used so as to give 5.0 parts by weight in terms of silicic acid produced as a result of hydrolysis of silica alkoxide. These production conditions are shown in Table 1 below.

  Next, the stability of the hydrolyzate of silica alkoxide was evaluated for each of the dopes of Examples 1 to 3, and the results obtained are shown in Table 2 below.

Here, the stability of the hydrolyzate of silica alkoxide is determined by measuring the absorbance of IR spectrum in the vicinity of 960 cm ⁻¹ of the dope of cellulose triacetate containing the silica alkoxide hydrolyzate. The IR spectrum absorbance of the dope after stagnation was compared, and the ratio of IR spectrum absorbance after stagnation for 24 hours / IR spectrum absorbance immediately after mixing was evaluated. Therefore, the closer this ratio is to 1, the better the stability of the silica alkoxide hydrolyzate, the more the pseudo-crosslinking reaction between the cellulose triacetate and the hydrolyzate of silica alkoxide is promoted, and consequently the dimensional stability of the cellulose triacetate film. Can be secured.

  Then, using each dope after stagnation for a predetermined time in Examples 1 to 3, a cellulose triacetate film was produced as follows using a solution casting film forming apparatus.

  A cellulose triacetate solution (dope) containing a hydrolyzate of silica alkoxide prepared as described above was allowed to flow from a casting die onto a support made of a driven rotating stainless steel endless belt having a mirror-finished surface. Then, a dope film, that is, a web was obtained, and the web reached the lower surface of the support made of an endless belt.

  Next, the web peeled off by the peeling roll was dried with drying air while passing through the drying zone to form a film, and then wound on a winding roll to produce a cellulose triacetate film having a target dry film thickness of 40 μm.

  About the cellulose triacetate film as an optical film obtained in Examples 1 to 3, the dimensional change rate and the deviation of the thickness direction retardation (Rt) were evaluated, and the obtained results are shown in Table 2 below. .

  Here, the dimensional change rate (dry) of the film was evaluated for 120 hours in an environment of a temperature of 90 ° C. and a humidity of 20% RH with respect to the dimensions (length in the width direction) immediately after the production of each cellulose triacetate film. Evaluation was made by taking a percentage of the dimension (width in the width direction) that was changed later. In addition, the evaluation of the dimensional change rate (wet) of the film was performed after holding for 300 hours in an environment of a temperature of 60 ° C. and a humidity of 90% RH with respect to the dimension immediately after the production of each cellulose triacetate film (length in the width direction). The percentage of the changed dimension (width in the width direction) was taken and evaluated.

  Further, the deviation of the thickness direction retardation (Rt) was evaluated by measuring the temperature of the cellulose triacetate film at a temperature of 23 ° C. with respect to the thickness direction retardation (Rt) value when kept in an environment of 23 ° C. and 20% RH for 24 hours. The difference from the thickness direction retardation (Rt) value of the film after being kept in an environment of 80% humidity for 24 hours was evaluated.

  For comparison, in the case of Example 1, after completion of mixing of the hydrolyzate of tetraethoxysilane (silica alkoxide) and cellulose triacetate, stainless steel was immediately (after about 15 minutes) without stagnation of this dope. A film cast on a support made of a steel endless belt and formed by a solution casting film forming method was unpractical because the surface appearance deteriorated.

Comparative Example 1
For comparison, a cellulose triacetate film is produced using the same dope constituent material as in Example 1, but in Comparative Example 1, a cellulose triacetate doped solvent is used as a reaction solvent for tetraethoxysilane (silica alkoxide). The main solvent, methylene chloride, was used at 75% by weight, which is outside the scope of the present invention. The amount of silica alkoxide hydrolyzate is 2.0 parts by weight in terms of silicic acid produced as a result of hydrolysis of silica alkoxide with respect to 100 parts by weight of cellulose triacetate, as in Example 2. A hydrolyzate of silica alkoxide was used to give The other points of Comparative Example 1 were carried out in the same manner as in Example 1 above, and the production conditions are shown in Table 1 below.

  Next, for the dope of Comparative Example 1, the stability of the hydrolyzate of silica alkoxide was evaluated, and the obtained results are shown in Table 2 below.

  Then, a cellulose triacetate film was produced in the same manner as in Example 1 using a solution casting film forming apparatus using the dope of Comparative Example 1 after the predetermined time.

About the obtained cellulose triacetate film of Comparative Example 1, the dimensional change rate and the deviation in the thickness direction retardation (Rt) were evaluated in the same manner as in Example 1, and the obtained results are shown in Table 2 below. Showed.

  As is clear from the results of Table 2 above, in Examples 1 to 3 of the present invention, when a hydrolyzate of tetraethoxysilane (silica alkoxide) is prepared, the main solvent of cellulose triacetate dope is used as a part of the reaction solvent. Since 65% of methylene chloride is added, further polymerization of the silica alkoxide hydrolyzate produced by the hydrolysis reaction is suppressed, and each molecule of the silica alkoxide hydrolyzate can be stably present in a scattered state. When mixed with triacetate, stable pseudo-crosslinking was possible between the cellulose triacetate and the silica alkoxide hydrolyzate, and the dope of the cellulose triacetate film had excellent silica alkoxide hydrolyzate stability.

  In addition, the cellulose triacetate film produced by casting the cellulose triacetate dope produced in Examples 1 to 3 of the present invention on a support made of a stainless steel endless belt by a solution casting film forming method is a dry condition and The dimensional change rate was very small under the wet conditions, the film had excellent dimensional stability, the deviation (ΔRt) in the thickness direction retardation of the film was very small, and the optical characteristics were stable.

  On the other hand, in Comparative Example 1, when 75% by weight of methylene chloride, which is the main solvent of the cellulose triacetate dope, was used as the reaction solvent for tetraethoxysilane (silica alkoxide), which is outside the scope of the present invention, Since the amount of methylene is too large, the reaction rate of hydrolysis of tetraethoxysilane is very low. Therefore, in the cellulose triacetate dope of Comparative Example 1, the stability of the hydrolyzate of silica alkoxide is very poor. It was. And the cellulose triacetate film produced by casting the cellulose triacetate dope produced in this Comparative Example 1 on a support made of a stainless steel endless belt by the solution casting film forming method has a very high dimensional change rate. It was large and inferior in dimensional stability, and the deviation in retardation (Rt) in the thickness direction of the film was large, so that the optical characteristics were unstable.

(Preparation of polarizing plate)
The cellulose triacetate films obtained in Examples 1 to 3 and Comparative Example 1 were each immersed in an aqueous sodium hydroxide solution having a concentration of 2 mol / liter at 60 ° C. for 2 minutes, washed with water, and then dried at 100 ° C. for 10 minutes. An alkali saponified cellulose triacetate film was obtained.

  Separately, a 120 μm thick polyvinyl alcohol film was immersed in 100 parts by weight of an aqueous solution containing 1 part by weight of iodine and 4 parts by weight of boric acid, and stretched 4 times at 50 ° C. to prepare a polarizing film. The alkaline saponified cellulose triacetate films of Examples 1 to 3 and Comparative Example 1 were bonded to both surfaces of the polarizing film, respectively, using a completely saponified polyvinyl alcohol 5% aqueous solution as an adhesive, and Examples 1 to 3 and Comparative Examples. 1 polarizing plate was produced.

  And about the polarizing plate of these Examples 1-3 and the comparative example 1, when the dimensional change rate was measured like said case, each cellulose triacetate film obtained in the said Examples 1-3 was polarizing plate. The polarizing plate used as a protective film for a film had excellent dimensional stability as well as the dimensional stability of the cellulose triacetate film used therefor. On the other hand, in the polarizing plate using the cellulose triacetate film obtained in Comparative Example 1, the dimensional stability was poor similarly to the dimensional stability of the cellulose triacetate film used therefor.

Claims (13)

  When producing a cellulose ester film as an optical film containing at least one metal alkoxide hydrolyzate, an organic solvent, a metal alkoxide hydrolyzate, and a cellulose ester are mixed to produce a cellulose ester film dope. A metal alkoxide hydrolyzate characterized in that when a metal alkoxide hydrolyzate is prepared, a metal main alkoxide is hydrolyzed by adding a dope main solvent dissolving a cellulose ester as a part of the reaction solvent.   2. The metal according to claim 1, wherein the ratio of the cellulose ester dope main solvent to the total solvent used when performing the hydrolysis reaction of the metal alkoxide is more than 0 wt% and 70 wt% or less. Alkoxide hydrolyzate.   The hydrolyzate of metal alkoxide according to claim 1 or 2, wherein the cellulose ester-doped main solvent is methylene chloride.   The metal alkoxide hydrolyzate according to any one of claims 1 to 3, wherein the metal alkoxide is silica alkoxide.   When producing a cellulose ester film as an optical film containing at least one metal alkoxide hydrolyzate, an organic solvent, a metal alkoxide hydrolyzate, and a cellulose ester are mixed to produce a cellulose ester film dope. When a hydrolyzate of the metal alkoxide is prepared, the metal alkoxide is hydrolyzed by adding a dope main solvent that dissolves the cellulose ester as a part of the reaction solvent. Preparation method of hydrolyzate solution.   The metal according to claim 5, wherein the ratio of the cellulose ester dope main solvent to the total solvent used in the hydrolysis reaction of the metal alkoxide is more than 0% by weight and 70% by weight or less. Preparation method of hydrolyzate solution of alkoxide.   The method for producing a hydrolyzate solution of metal alkoxide according to claim 5 or 6, wherein the cellulose ester dope main solvent is methylene chloride.   The method for producing a hydrolyzate solution of metal alkoxide according to any one of claims 5 to 7, wherein the metal alkoxide is silica alkoxide.   A hydrolyzate of the metal alkoxide according to any one of claims 1 to 4, an organic solvent, and a cellulose ester are mixed to produce a dope of a cellulose ester film, and the dope of the cellulose ester film is a solution. A method for producing an optical film using a hydrolyzate of a metal alkoxide, wherein an optical film comprising a cellulose ester film is produced by casting on a metal support by a casting film forming method.   After mixing the hydrolyzate of metal alkoxide, organic solvent, and cellulose ester, the dope of the cellulose ester film is allowed to stand for 30 minutes to 72 hours, or stir by stirring at a rotational speed of 60 rpm or less. The method for producing an optical film according to claim 9, wherein the optical film is produced by:   The optical film according to claim 9 or 10, wherein the dope of the cellulose ester film is prepared by mixing a hydrolyzate of a metal alkoxide, an organic solvent, a cellulose ester, a plasticizer and / or an ultraviolet absorber. Manufacturing method.   It manufactured with the manufacturing method of the optical film as described in any one of Claims 9-11, The optical film characterized by the above-mentioned.   The optical film of Claim 12 comprises at least any one of the two polarizing plate protective films arrange | positioned at the both sides of a polarizing film, The polarizing plate characterized by the above-mentioned.