TWI444668B - An optical film and a polarizing plate and a liquid crystal display device using the same - Google Patents

Description

Optical film and polarizing plate and liquid crystal display device using the same

The present invention relates to an optical film comprising a cellulose ester formed by a melt casting method, a polarizing plate using the same, and a liquid crystal display device.

An optical film having a cellulose ester (hereinafter, also referred to simply as a cellulose ester film), which is highly transparent. Low complex refractive index. From the viewpoint of the adhesion of the polarizer, etc., it can be used as a polarizing plate or the like as an optical film for protecting a photoreceptor for a photo negative film or a photoconductor for a liquid crystal display device. Further, as another use of the liquid crystal display device, various functional films such as a retardation film, a viewing angle expansion film, and an antireflection film for a plasma display can be used, and various functional films such as an organic EL display can be used.

The liquid crystal display device has greatly increased its production amount in recent years due to its extremely thinness and light weight, and the demand is increasing. Further, since the television using the liquid crystal display device has a thin and light characteristic, it is possible to produce a large-sized television which cannot be realized by a television using a cathode ray tube, and the demand for a polarizer and a polarizing plate protective film constituting the liquid crystal display device is also increased. As the polarizing plate protective film, a cellulose ester film is generally used from the viewpoint of excellent optical characteristics.

These cellulose ester films have hitherto been produced by solution casting. The so-called solution casting method is that after the solution in which the cellulose ester is dissolved in a solvent is cast to obtain a film shape, the solvent is evaporated. After drying, a film forming method of the film is obtained. The film formed by the solution casting method has high planarity, so it can be obtained by using this. A high-quality liquid crystal display device that does not produce spots.

However, the solution casting method requires a large amount of organic solvent, causing a problem of causing a large environmental load. From the viewpoint of the solubility characteristics, the cellulose ester film is formed by using a halogen-based solvent having a large environmental load, so that the use of a solvent is particularly required to be reduced, and it is difficult to increase the yield of the cellulose ester by solution casting. film. Therefore, a film forming method which does not use an organic solvent, for example, a film forming method by heating and melting can be used.

On the other hand, as a cellulose ester film used for a protective film of a polarizing plate used for a liquid crystal display device, a cellulose triacetate film has been used in the past. Generally, the polarizing plate is formed on both sides of a polarizing film having a iodine or a dye-adsorbed polyvinyl alcohol film, and is laminated with a transparent resin layer, and a cellulose triacetate film is used as the transparent resin layer. Widely used. However, cellulose triacetate of a cellulose ester which is generally used for casting a solution for film formation is used for melt film formation, and cellulose triacetate is a cellulose ester having a melting start temperature higher than a decomposition start temperature. Therefore, it is difficult to use for melt film formation.

In recent years, the cellulose ester has been replaced with a fluorenyl group or a butyl fluorenyl group at a specific ratio by an ethylene group, and is used as a silver salt photograph (for example, refer to Patent Document 1) or a polarizing plate protective film (for example, reference) Patent Documents 2 and 3), attempts have been made to melt-form a cellulose ester as described above. When the degree of substitution of the propyl sulfhydryl group or the butyl sulfhydryl group is high, the viscosity at the time of melting becomes small, so that it is advantageous for melt film formation, but the mechanical strength or deterioration of the film after film formation is reversed, and it is impossible to obtain a silver salt photograph. And the function of the polarizing plate to protect the film. On the other hand, the substitution degree of propyl sulfhydryl or butyl sulfhydryl is low. When the mechanical strength is increased, the viscosity at the time of melting is increased. When the mold is extruded and cast on a cooling drum or a cooling conveyor belt, it is difficult to flatten, and uneven shape and pressure unevenness are likely to occur. As a result, it was judged that the planarity or the rollability of the physical properties of the obtained film deteriorated, and the variation in the retention property of the optical characteristics was large.

When a cellulose ester is melt-formed, a specific deterioration preventive agent can be added (for example, refer to Patent Document 4). It is known that the deterioration of the chemical properties of the polymer material (coloring and molecular weight reduction) can be prevented by the addition of the deterioration preventing agent. However, if the combination of the polymer material and the deterioration preventing agent is not appropriate, it is a counter effect, in other words, the change is high. The deterioration of molecular materials makes them a problem. However, if there is no deterioration in chemical properties, the optical characteristics are deteriorated by the time. In such a case, the use of the cellulose ester for the optical use is a fatal problem, and it is an important problem to select an appropriate deterioration preventive agent for the polymer material. On the other hand, the cellulose ester which is melt-formed is not only stable at the time of melt film formation, but also stability after melt film formation. In other words, it is important that no defects are used during the period in which the cellulose ester is used to construct any product and the product is delivered to the consumer. In the conventionally known technique, there are problems in the stability of the film during the melt film formation and the long period after the melt film formation, and the construction of the high-height stabilization technology is expected.

However, when a polarizing plate is bonded to a protective film and a polarizer, the water-soluble adhesive is easily applied, and the triacetyl cellulose film is immersed in a high-temperature, high-concentration alkali solution to perform so-called alkalization treatment. Thereafter, the surface of the film is hydrophilized, and an adhesive is applied and adhered to the polarizer.

From the viewpoint of easy adhesion to the above-mentioned polarizer, as a polarizing plate The transparent resin film for a protective film has used triacetyl cellulose, and one of the reasons why it has not been replaced by another film is that even a polymer film such as a polyester film, a polycarbonate film, or a cyclic olefin resin film is passed through. It is also impossible to obtain easy adhesion to a polarizer after alkalization treatment.

Attempts have been made to improve the various properties of the cellulose ester film by specifying the degree of substitution of the thiol group of the cellulose ester, for example, an ethylene group, a propyl group, or a butyl group (see, for example, Patent Document 5). Moreover, the cellulose ester film which is substituted with a specific ratio of a propyl fluorenyl group or a butyl fluorenyl group is an easily bondable one, and a propyl fluorenyl group or a butyl fluorenyl group, compared with a polymer film other than a cellulose ester. When the degree of substitution is too high, the alkalization treatment is difficult to carry out, and as a result, it is judged that there is a problem that the adhesion is deteriorated, and that mechanical properties and optical properties are not sufficient. In particular, when the propyl fluorenyl group and the butyl sulfonium group are compared, the mechanical properties and the optical properties are extremely deteriorated by the combination of the butyl sulfhydryl groups only in the difference of one carbon number.

Therefore, the current situation is expected to replace the triethylenesulfonated cellulose film formed by the solution casting method, which has environmental adaptability, high flatness and alkalization treatment adaptability, and small variation in rollability and retention property, and The appearance of a melt-film-formed optical film with good durability over a long period of time.

However, the cellulose ester film is generally wound up and stored under the original film roll to be stored and transported. Therefore, when the melt-film-formed film is wound on the original film roll of the winding core for a long period of time, there is a horseback failure or a failure of the original film roll, and a failure called a core transfer is likely to occur. At the beginning, the film is prone to collapse.

The so-called horseback fault is that the original film is rolled into a U-shaped shape like a horseback. The failure of forming a strip-shaped convex portion having a pitch of about 2 to 3 cm in the vicinity of the center portion causes deformation of the film, so that when the polarizing plate is processed, the surface is deformed. Up to now, the horseback failure can be reduced by adjusting the dynamic friction coefficient of the bottom materials or the height of the piping processing (embossing) on both sides.

Further, the core transfer is a failure of the film deformation caused by the unevenness of the core or the film.

In the film produced by the solution casting in the past, it is known that these troubles have not become a serious problem, but the film produced by the melt film formation has become a serious problem because the planarity of the film is too low.

In particular, in recent years, with the large screen, the width of the original film roll is required to be enlarged, and the length of the roll is lengthened. Therefore, the original film roll has a tendency to increase in width and the original film roll load tends to increase, and these failures are more likely to occur, so that improvement is expected.

Patent Document 1: Japanese Patent Publication No. 6-501040 Patent Document 2: JP-A-2000-352620 Patent Document 3: JP-A-2006-111796 Patent Document 4: JP-A-2006-241428 Patent Document 5: JP-A-2006-111842

The present invention has been made in view of the above problems, and an object of the present invention is to provide an excellent environmental adaptability, good mechanical properties, and light.

The optical film of the melt-formed film with good characteristics and durability is more specifically provided to provide an optical film, planarity, alkalization treatment which is less likely to cause deformation failure of the original film roll such as a horseback failure or a convex failure. An optical film having high adaptability and small variation in rollability and retention property, and a polarizing plate and a relatively high contrast liquid crystal display device which are excellent in durability over a long period of time using the optical film.

The inventors of the present invention have been made to solve the above problems, and have conducted detailed review and found that all problems can be solved by using a film having a specific substituent type and amount of cellulose ester melt-filmed, and the present invention has been completed.

That is, the above problems of the present invention are achieved by the following constitution.

An optical film comprising at least one of a plasticizer and a film forming material of a cellulose ester which is heated and melted and formed into a film by a melt casting method, which is characterized in that a substituent of the cellulose ester is used. The type and the cellulose ester having the degree of substitution satisfying the conditions of the following formulas (1) to (4) are formed into a film.

Formula (1) 1.25≦X≦1.43 Equation (2) 1.15≦Y≦1.33 Equation (3) 2.40≦X+Y<2.75 Formula (4)-0.05≦X-Y<0.20

Wherein X represents the degree of substitution by an ethyl group, and Y represents the degree of substitution by a propyl group. 〕

2. The optical film according to the above 1, characterized in that the cellulose is The temperature Td (1.0) at which the mass of the ester is reduced by 1% is 270 ° C or higher.

3. The optical film according to the above 1 or 2, wherein the film forming material further contains at least one of a phenol compound.

4. The optical film according to any one of the above 1 to 3, wherein the film forming material further contains at least one of a phosphorus compound.

5. The optical film according to any one of the above 1 to 4, wherein the film forming material further contains at least one of an alkyl radical scavenger.

6. The optical film according to the above 1 or 2, wherein the film forming material further contains at least one of a phenolic compound, at least one of a phosphorus compound, and at least one of an alkyl radical scavenger. .

The optical film according to any one of the above-mentioned items, wherein the phenolic compound is a hindered phenol compound.

The optical film according to any one of the items 4 to 7, wherein the phosphorus compound is a phosphite compound.

The optical film according to any one of the items 5 to 8, wherein the alkyl radical scavenger is a compound represented by the following general formula (1) or a compound represented by the following general formula (2).

In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₂ and R ₃ each independently represent an alkyl group having 1 to 8 carbon atoms. 〕

[wherein R ₁₂ to R ₁₅ each independently represent a hydrogen atom or a substituent, R ₁₆ represents a hydrogen atom or a substituent, and n represents an integer of 1 to 4. When n is 1, R ₁₁ represents a substituent, and when n is an integer of 2 to 4, R ₁₁ represents a 2 to 4 valent linking group. 〕

The optical film according to any one of the items 1 to 9, wherein the plasticizer is a polyol ester.

The optical film according to any one of the items 1 to 10, wherein the film forming material further contains a benzotriazole compound.

A polarizing plate characterized in that the optical film of any one of the above 1 to 11 is provided on at least one surface of the polarizer.

A liquid crystal display device characterized in that the polarizing plate described in the above 12 is used for at least one surface of a liquid crystal cell.

According to the present invention, it is possible to provide an optical film which is less likely to cause deformation failure of a raw film roll such as a horseback failure or a convex failure, which has high flatness and alkalization treatment, and has less variation in rollability and retention. An optical film and a polarizing plate which is excellent in durability over a long period of time using the optical film and higher Comparative liquid crystal display device.

The best form of implementing the invention

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

The present invention is an optical film which can obtain excellent mechanical properties, optical properties, and durability. By using such an optical film, an optical film such as a protective film for a high-quality polarizing plate, an antireflection film, or a retardation film can be obtained, and a liquid crystal display device having high display quality can be obtained.

The present invention is characterized in that a cellulose ester film formed by melt casting is used as an optical film. In the present invention, it is not necessary to dissolve the film forming material in a solvent as in the case of solution casting, and it is defined as a melt casting method by heating the film forming material to make it flowable in a flowable state.

The molding method of heating and melting can be further classified into a melt extrusion molding method, a pressure molding method, an expansion method, an injection molding method, a blow molding method, an extension molding method, and the like. Among them, an optical film excellent in mechanical strength and surface precision is preferable, and a melt extrusion method is preferred.

After the film forming material is heated to express the fluidity, the film forming method is carried out on the drum or on the endless conveyor belt, and the film forming method can be used as the melt casting film forming method in the melt casting method of the present invention.

Therefore, the optical film of the present invention is characterized in that a film forming material containing at least one type of plasticizer and the following cellulose ester is heated and melted at a melting temperature of preferably 200 ° C to 270 ° C. An optical film formed by a melt casting method.

The respective film forming materials will be described below.

"Cellulose Ester" The cellulose ester used in the melt casting method of the present invention is a cellulose ester which satisfies the following formulas (1) to (4) when the degree of substitution of the ethyl fluorenyl group is X and the degree of substitution of the propyl fluorenyl group is Y. . Such cellulose esters are generally referred to as cellulose acetate propionates. Further, only one of the following formulas, any two, or any three of them can be satisfied, and all of the above problems cannot be solved, and the above four points must be satisfied at the same time.

Formula (1) 1.25≦X≦1.43 Equation (2) 1.15≦Y≦1.33 Equation (3) 2.40≦X+Y<2.75 Formula (4)-0.05≦X-Y<0.20

Wherein, for formula (1), it is preferably 1.30≦X≦1.42, and for formula (2), it is preferably 1.18≦Y≦1.32, and for formula (3), it is preferably 2.50≦X+Y≦2.73. For the formula (4), 0.01 ≦ X - Y ≦ 0.18 is preferred.

Next, the degree of substitution of the thiol group (ethyl fluorenyl group and propyl fluorenyl group) of the cellulose ester used in the present invention will be described in detail.

In the cellulose, one unit of the two units, three positions, and six positions of one unit of glucose has a total of three hydroxyl groups, and the total degree of substitution is a value represented by the number of thiol groups bound to an average of one unit of glucose. Therefore, the maximum degree of substitution is 3.00, and the portion not substituted with the above mercapto group is generally present in the form of a hydroxyl group. Further, the 2nd position and the 3rd position are a 2-stage hydroxyl group, and the 6-position is a 1-stage hydroxyl group, and the ethyl hydrazide group and the propyl hydrazine are substituted at which position at a ratio, and the cellulose can be obtained. The higher order structure or physical properties of the ester change. However, in the optical film of the present invention, it is applicable only to the cellulose ester which satisfies the conditions of the above formulas (1) to (4), regardless of the respective substitution positions and ratios of the ethyl fluorenyl group and the propyl group. Further, the degree of substitution of the acetyl group and the propyl group is determined according to the method specified in ASTM D817-96.

The cellulose ester used in the present invention is preferably a number average molecular weight (Mn) of 50,000 to 150,000, preferably a number average molecular weight of 55,000 to 120,000, and preferably having a number average molecular weight of 60,000 to 100,000. .

Further, the cellulose ester used in the present invention is preferably a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of from 1.3 to 5.5, particularly preferably from 1.5 to 5.0, more preferably from 1.7 to 4.0, most preferably A cellulose ester of 2.0 to 3.5.

Further, Mn and Mw/Mn can be calculated by gel permeation chromatography (GPC) in the following manner.

The measurement conditions are as follows.

Solvent: tetrahydrofuran Device: HLC-8220 (Tosoh system) Column: TSKgel SuperHM-M (made by Tosoh) Column temperature: 40 ° C Sample concentration: 0.1% by mass Injection volume: 10 μ l Flow rate: 0.6ml/min Proofreading curve: Standard polystyrene: using PS-1 (Polymer A proofreading curve made by a sample of Mw=2,560,000~580, manufactured by Laboratories.

When the cellulose ester in the film forming material is in the range of 70% by mass to 99% by mass, excellent melt castability and stability can be exhibited in the presence of additives such as a deterioration preventing agent, a plasticizer, and an ultraviolet ray inhibitor which will be described later. The film can impart excellent properties as an optical film. When the content of the cellulose ester is 70% by mass or less, the additive may leak out or the mechanical strength of the film may become small. In addition, when the amount of the other additives necessary for the optical film is 1.0% by mass or less (the content of the cellulose ester is 99% or more), it is difficult to satisfy the required physical properties. More preferably, the content of the cellulose ester is from 80 to 95% by mass.

The raw material cellulose of the cellulose ester used in the present invention may be wood pulp or cotton velvet, and the wood pulp may be conifer or broad-leaved tree, but a conifer is preferred. From the viewpoint of the peeling property at the time of film formation, it is preferable to use cotton velvet. These obtained cellulose esters may be suitably mixed or used alone.

For example, it is possible to use cellulose pulp from cellulose pulp: cellulose ester from wood pulp (coniferous tree): the ratio of cellulose ester from wood pulp (broadleaf tree) is 100:0:0, 90:10:0, 85: 15:0, 50:50:0, 20:80:0, 10:90:0, 0:100:0, 0:0:100, 80:10:10, 85:0:15, 40:30: 30.

The cellulose ester of the present invention can be synthesized by referring to a known method. For example, the hydroxyl group of the raw material cellulose can be substituted with an acetic anhydride or a propionic anhydride according to a conventional method, and the ethyl hydrazide group and the propyl group can be substituted. The method for synthesizing the cellulose ester is not particularly limited, and for example, reference may be made to the special opening. The synthesis is carried out by the method described in No. 10-45804 or JP-A-6-501040. Further, the amount of acetic anhydride and propionic anhydride to be used may be appropriately changed, and the cellulose ester of the above formulas (1) to (4) may be synthesized.

The content of the alkaline earth metal of the cellulose ester used in the present invention is preferably in the range of 1 to 50 ppm. When the amount exceeds 50 ppm, the adhesion of the lip to the die may increase or the slitting portion may be broken when the heat is extended or after the heat extension. It is also easy to break when it is less than 1 ppm, and the reason is not clear. It is preferably in the range of 1 to 30 ppm. The alkaline earth metal is a total content of Ca and Mg, and can be measured by an X-ray photoelectron spectroscopy analyzer (XPS).

The residual sulfuric acid content in the cellulose ester used in the present invention is preferably in the range of 0.1 to 45 ppm in terms of sulfur element. It can be assumed that they are contained in the form of salt. When the residual sulfuric acid content exceeds 45 ppm, the deposit of the lip of the mold at the time of heat fusion may increase. Further, it is not preferable because it is easily broken at the time of heat stretching or slitting after heat stretching. Less is better, but when it is less than 0.1, it is easy to break, so it is not good, and the reason has not been clarified. It is preferably in the range of 1 to 30 ppm. The residual sulfuric acid content can be determined by the method specified in ASTM D817-96.

The content of the free acid in the cellulose ester used in the present invention is preferably from 1 to 500 ppm. When it exceeds 500 ppm, the deposit of the lip of the mold increases, and it is easy to break. It is preferably in the range of 1 to 100 ppm, and is more difficult to fracture. Especially in the range of 1 to 70 ppm is preferred. The free acid content can be determined by the method specified in ASTM D817-96.

Washing the synthesized cellulose ester compared to when used in solution casting Further, by allowing the residue to be more sufficiently carried out, the residual alkaline earth metal content, the residual sulfuric acid content, and the residual acid content are preferably in the above range. Further, the cellulose ester may be washed, and in addition to water, a weak solvent such as methanol or ethanol, or a mixed solvent of a weak solvent and a good solvent which is a weak solvent may be used, and an inorganic substance other than the residual acid may be removed. Low molecular organic impurities. Further, the cellulose ester is preferably washed in the presence of a deterioration preventing agent, and the heat resistance of the cellulose ester and the film stability can be improved. The deterioration preventing agent to be used can only inactivate the radical generated by the cellulose ester, or can inhibit the deterioration of the cellulose ester caused by the addition reaction of the free gene produced by the cellulose ester with oxygen. , no restrictions.

Further, in order to improve the heat resistance, mechanical properties, optical properties, and the like of the cellulose ester, it is dissolved in a good solvent of the cellulose ester, reprecipitated in a weak solvent, filtered, or stirred and suspended in a weak solvent, and filtered. It can remove low molecular weight components and other impurities of cellulose ester. In this case, in the same manner as the washing of the cellulose ester, it is preferably carried out in the presence of a deterioration preventing agent.

The deterioration preventing agent used for washing the cellulose ester may remain in the washed cellulose ester. The residual amount is preferably 0.01 to 2000 ppm, preferably 0.05 to 1000 ppm. More preferably, it is 0.1 to 100 ppm.

Moreover, after the reprecipitation treatment of the cellulose ester, other polymers or low molecular compounds may also be added.

Moreover, it is preferable that the cellulose ester used in the present invention has a small amount of foreign matter when it is used as a film. The bright spot foreign matter is such that the two polarizing plates are arranged in the orthogonal direction (orthogonal Nicol), and a cellulose ester film is disposed therebetween, wherein one side is irradiated with light of the light source, and when the cellulose ester film is observed from the other side, light is seen. The point where the light of the source leaks out. In this case, it is preferable that the polarizing plate used for the evaluation is a protective film having no bright foreign matter, and it is preferable to use a glass plate for the protection of the polarizer. One of the reasons for highlighting foreign matter is presumed to be cellulose which is not vinegarized or low in acetalization of cellulose ester, and cellulose ester having less bright foreign matter (using a cellulose ester having less dispersion degree of substitution), In at least one of the process of filtering the molten cellulose ester or the cellulose ester, or the process of obtaining a precipitate, the bright spot foreign matter can be removed as a single solution state through the same filtration step. The molten resin is preferred because of its high viscosity.

The thinner the film thickness, the smaller the number of bright spots per unit area, and the smaller the content of the cellulose ester contained in the film, the less the foreign matter tends to be bright. The bright spot is the bright spot having a diameter of 0.01 mm or more and 200 pieces/cm. ² or less is preferable, preferably 100 pieces/cm ² or less, more preferably 50 pieces/cm ² or less, more preferably 30 pieces/cm ² or less, and 10 pieces/cm ² or less are more excellent, and none of them are the most. good. Further, the bright spot of 0.005 to 0.01 mm or less is preferably 200 pieces/cm ² or less, preferably 100 pieces/cm ² or less, more preferably 50 pieces/cm ² or less, and most preferably 30 pieces/cm ² or less. , 10 / cm ² or less is more excellent, none is the best.

When the bright foreign matter is removed by melt filtration, it is preferred to filter the cellulose ester alone, and to filter and add a cellulose ester composition such as a deterioration inhibitor or a plasticizer to improve the removal efficiency of the bright foreign matter. Of course, the cellulose ester can be dissolved in a solvent and then reduced by filtration. It is also possible to filter suitable mixtures of UV absorbers and other additives. Filtered to have a viscosity of 10,000 Pa. s below Row filtration is preferred, preferably 5000 Pa. s or less, more preferably 1000Pa. Below s, the best is 500Pa. s below. As the filter material, a fluorinated resin such as glass silicate, cellulose oxime, filter paper, or tetrafluoride-extended ethyl resin is preferably used, and ceramics, metals, and the like are particularly preferably used. The absolute filtration accuracy is preferably 50 μm or less, preferably 30 μm or less, more preferably 10 μm or less, and most preferably 5 μm or less. These can be used in combination as appropriate. The filter material may be of a surface type or a depth type, but the depth type is less likely to be blocked.

In another embodiment, the cellulose ester of the solvent may be dried after the cellulose ester of the raw material is dissolved in the solvent at least once. In this case, the dried cellulose ester is dissolved in a solvent together with at least one of a deterioration inhibitor, a plasticizer, an ultraviolet absorber, and a matting agent. As the solvent, a good solvent used in a solution casting method such as dichloromethane, methyl acetate or dioxolane can be used, and a weak solvent such as methanol, ethanol or butanol can be used. During the dissolution process, it can be cooled to below -20 ° C or heated above 80 ° C. By using such a cellulose ester, it is easy to make each additive in a molten state uniform, and it is possible to make optical characteristics uniform.

The optical film of the present invention is a polymer component which can be suitably mixed with a cellulose ester. The mixed polymer material and the cellulose ester are preferably excellent in compatibility, and the transmittance in the case of a film is 80% or more, more preferably 90% or more, and particularly preferably 92% or more.

Since the cellulose ester of the present invention is used for melt film formation, it must be carried out under the condition that the cellulose ester itself is heated and melted until it is formed into a film. The present inventors have found that the stability and melting of the film are not so melted. After film formation The mechanical properties, optical properties, and durability of the cellulose ester film have a correlation with the temperature Td (1.0) at which the cellulose ester before heating and melting is reduced in air by 1%. And for the cellulose ester which satisfies the above formulas (1) to (4) while using only the present invention. The above problem can be solved, but when the Td (1.0) is high, the problem is better solved, Td (1.0) is preferably 270 ° C or more, more preferably 280 ° C or more, and 290 ° C or more is optimal. In order to increase the Td (1.0) of the cellulose ester, in the synthesis of the cellulose ester, when the cellulose ester finally taken out is filtered and washed, the water is sufficiently washed until the pH of the washing liquid is neutral. Can be improved. However, the detailed reason is not clear. However, in the case of the type of cellulose ester, when the transition is washed, the mechanical properties such as breakage easily deteriorate, but the fiber of the above formula (1) to (4) is satisfied in the present invention. The ester ester shows that the washing does not cause deterioration of mechanical properties. Further, the air 1% mass reduction temperature Td (1.0) can be measured by a commercially available differential thermogravimetric analysis (TG-DTA) apparatus. Generally, a cellulose ester contains a small amount of water, so care must be taken when measuring. Specifically, the sample was temporarily held at 100 ° C, and it was confirmed that there was no method in which the mass was reduced due to the evaporation of water, and the mass loss due to the temperature increase at this time was measured. However, there is no upper limit for Td (1.0), although the higher the estimation, the better, but in consideration of avoiding the excessive burden of the washing step of the cellulose ester, the actual upper limit is about 300 to 310 °C.

The cellulose ester of the present invention can further improve the stability at the time of heating by the combination with the deterioration preventing agent, and it is surprisingly found that when combined with the deterioration preventing agent described below, it is possible to obtain a horseback failure or a convex shape. Deformation failure of the original film roll such as failure, flatness, alkalization treatment adaptability, rollability, lag A cellulose ester film excellent in variability and durability.

Deterioration Preventive Agent The deterioration preventing agent is a material which can inhibit the decomposition of the polymer by heat, oxygen, moisture, acid or the like by chemical action. The optical film of the invention is formed at a high temperature of 200 ° C or higher, so that it is easy to cause decomposition of the polymer. In the case of deterioration, it is preferred that the deterioration preventing agent is contained in the film forming material.

The acid generated by the oxidation prevention and decomposition of the film-forming material captures, inhibits, or inhibits the decomposition reaction of the light or heat radical gene, including unresolved decomposition reaction, and suppresses deterioration mainly by coloring or molecular weight reduction. A deterioration inhibitor is used to form a volatile component caused by decomposition of the material.

Examples of the deterioration preventing agent include an antioxidant, a hindered amine light stabilizer, an acid scavenger, and a metal inerting agent, but are not limited thereto. Japanese Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. In the above, for the purpose of the present invention, it is preferred that the film forming material contains an antioxidant as a deterioration preventing agent.

The amount of the deterioration preventing agent in the film forming material to be used in the present invention may be at least one selected from the group consisting of the amount of the cellulose ester of the present invention, and the amount of the deterioration preventing agent added is 0.01% by mass or more and 10% by mass or less. More preferably, it is 0.1% by mass or more and 5.0% by mass or less, and most preferably 0.2% by mass or more and 2.0% by mass or less.

Further, when the amount of the deterioration preventing agent added is more than the above-mentioned addition amount range, From the viewpoint of the compatibility with the cellulose ester, the transparency as an optical film is lowered, and the film may become brittle.

The film forming material is intended to avoid deterioration or hygroscopicity of the material, and the material can be classified into one or a plurality of kinds of particles. The granulation can improve the miscibility or compatibility of the melt at the time of heating, or can ensure the optical uniformity of the obtained film.

When the film forming material is to be heated and melted, and when it is heated and melted, it can be used in the subsequent step, and when it is used as a product for the consumer, if the above-mentioned deterioration preventing agent is present, the strength or optical which can reduce the deterioration or decomposition of the material can be reduced. It is preferable from the viewpoint of deterioration of transparency or maintaining the inherent strength of the material.

The film forming material is remarkably deteriorated upon heating, and cannot be used as an optical film after being colored. Further, when used as an optical compensation film for a liquid crystal display device, the retention step (extension step) is performed after the casting step, but if the film forming material is significantly deteriorated by heating, the formed film becomes brittle. In the stretching step, breakage is likely to occur, and the retention value of the objective optical compensation film cannot be expressed. Further, when used as a polarizing plate protective film for a liquid crystal display device, deterioration of the film forming material is disadvantageous for the adhesion to the polarizer.

In the case where the above-described deterioration preventing agent is present, it is possible to suppress the formation of a coloring matter in the visible light region during the heating and melting, or to form a material which is formed by decomposing the volatile component or the like after the heating and melting and the film after heating and melting. Or the decrease in the haze value is preferable from the viewpoint that the deterioration of the optical film is poorly suppressed or eliminated.

In the present invention, the display image of the liquid crystal display device is affected when the haze value of the optical film of the present invention exceeds 1%. Therefore, the haze value is preferably less than 1%, more preferably less than 0.5%. Further, when the yellowness (yellow index Y1) is used as an indicator of the coloring property, it is preferably 3.0 or less, more preferably 1.0 or less. The yellowness is measured in accordance with JIS-K7103.

In the storage or film formation step of the above-mentioned film forming material, the deterioration reaction may be caused by oxygen or moisture in the air. At this time, the stabilization effect of the above-mentioned deterioration preventing agent is combined to reduce the humidity in the air. The present invention can be preferably carried out at an oxygen concentration. As a known technique, the use of nitrogen or argon as an inert gas, degassing operation under reduced pressure to vacuum, and operation in a closed environment may be used in at least one of the above methods. The method is used together. It is preferable to reduce the deterioration of the material by reducing the probability of contact between the film forming material and oxygen in the air.

Moreover, since the optical film of the present invention can also be used as a polarizing plate protective film, the above-described deterioration preventing agent in the film forming material can be improved from the viewpoint of improving the storage stability with respect to the polarizer constituting the polarizing plate and the polarizing plate of the present invention. Its existence plays an important role.

In the liquid crystal display device using the polarizing plate of the present invention, when the deterioration preventing agent is present in the optical film of the present invention, the temporal storage stability of the optical film can be improved from the viewpoint of suppressing the deterioration or deterioration. It is preferable that the display quality of the liquid crystal display device is improved and the optical compensation design can exhibit its function over a long period of time.

"Antioxidants" The cellulose ester promotes decomposition not only by heat but also by oxygen at a high temperature. Therefore, it is preferable that the optical film of the present invention contains an antioxidant as a deterioration preventing agent.

The antioxidant which is useful in the present invention is not particularly limited as long as it can suppress deterioration of the material for forming a film by oxygen, and examples thereof include a phenol compound, a phosphorus compound, a sulfur compound, and an alkyl group. A base scavenger, a peroxide decomposer, an oxygen scavenger, and the like. Among them, a phenol compound, a phosphorus compound, and an alkyl radical scavenger are preferred, and a phenol compound and a phosphorus compound 2 are preferably used in combination, and a phenol compound, a phosphorus compound, and an alkyl radical are trapped. The third of the agents is best used. By adding these compounds, it is possible to prevent coloring or strength reduction of the molded body due to heat or thermal oxidative degradation during melt molding without lowering transparency, heat resistance and the like. Each of these compounds may be used singly or in combination of two or more kinds, and the amount thereof may be appropriately selected within the range not impairing the object of the present invention, but the quality of the cellulose ester of the present invention is 0.01% by mass or more and 10% by mass. % or less is more preferably 0.1% by mass or more and 5.0% by mass or less, and most preferably 0.2% by mass or more and 2.0% by mass or less.

(phenolic compound) The phenolic compound is a known compound, and in addition to the alkyl-substituted phenol such as t-butylphenol or p-(1,1,3,3-tetramethylbutyl)phenol, for example, U.S. Patent No. 4,839,405 The 2,6-dialkylphenol-inducing compound and the so-called hindered phenol-based compound described in the columns 12 to 14 of the specification are preferably hindered phenol-based compounds.

Specific examples of the hindered phenol phenol-based compound include n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and n-octadecyl 3 -(3,5-di-t-butyl-4-hydroxyphenyl)-acetate, n-octadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n -hexyl 3,5-di-t-butyl-4-hydroxyphenyl benzoate, n-dodecyl 3,5-di-t-butyl-4-hydroxyphenyl benzoate, Neo-dodecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, dodecyl β(3,5-di-t-butyl-4-hydroxyl Phenyl)propionate, ethyl alpha-(4-hydroxy-3,5-di-t-butylphenyl)isobutyrate, octadecyl alpha-(4-hydroxy-3,5-di -t-butylphenyl)isobutyrate, octadecyl α-(4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-(n- Octylthio)ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2-(n-octylthio)ethyl 3,5-di-t-butyl-4- Hydroxy-phenyl acetate, 2-(n-octadecylthio)ethyl 3,5-di-t-butyl-4-hydroxyphenylacetic acid , 2-(n-octadecylthio)ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2-(2-hydroxyethylsulfanyl)ethyl 3,5- Di-t-butyl-4-hydroxybenzoate, diethylethylene glycol bis-(3,5-di-t-butyl-4-hydroxy-phenyl)propionate, 2-(n -octadecylthio)ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, stearylamine N,N-bis-[stretch ethyl 3-( 3,5-di-t-butyl-4-hydroxyphenyl)propionate], n-butylimine N,N-bis-[extended ethyl 3-(3,5-3-t-butyl) 4-hydroxyphenyl)propionate], 2-(2-stearyloxyethylthio)ethyl 3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-stearyloxyethylthio)ethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate, 1,2-propanediol bis-[3-( 3,5-di-t-butyl-4-hydroxyphenyl)propionate], ethylene glycol bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid Ester], neopentyl glycol Bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], ethylene glycol bis-(3,5-di-t-butyl-4-hydroxyphenyl) Acetate), glycerol-l-n-octadecanoate-2,3-bis-(3,5-di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol-肆-[ 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate], 3,9-bis-{2-[3-(3-tert-butyl-4- Hydroxy-5-methylphenyl)propenyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,1,1 - Trimethylolethane-paraxyl-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], sorbitol hexa-[3-(3,5-di -t-butyl-4-hydroxyphenyl)propionate], 2-hydroxyethyl 7-(3-methyl-5-tbutyl-4-hydroxyphenyl)propionate, 2-stearyl醯oxyethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate, 1,6-n-hexanediol-bis[(3',5'-di -t-butyl-4-hydroxyphenyl)propionate], pentaerythritol-indole (3,5-di-t-butyl-4-hydroxycinnamate). Phenol compounds of the above type are commercially available, for example, from Ciba Specialty Chemicals under the trade names "IRGANOX 1076" and "IRGANOX 1010".

(phosphorus compound) The phosphorus-based compound of the present invention includes a phosphate compound and a phosphite compound. Specific examples of the phosphate ester compound include triphenyl phosphate, diphenylisodecyl phosphate, phenyl diisodecyl phosphate, decylphenyl phosphate, and diterpene. Phenyl) phosphate, ginseng (2,4-di-t-butylphenyl) phosphate, ginseng (2,4-di-t-butyl-5-methylphenyl) phosphate, 10- (3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxo-10-phosphinophen-10-oxide, 6-[3-(3-t - Butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepine, a monophosphate compound such as tridecyl phosphate; 4,4'-butylene-bis(3-methyl-6-t-butylphenyl-di-tridecyl phosphate), 4,4'- A diphosphate-based compound such as isopropylidene-bis(phenyl-di-alkyl (C12-C15) phosphate). Phosphate-based compounds of the above type, for example, may be "Sumilizer GP" by Sumitomo Chemical Co., Ltd., ADK STAB PEP-24G" by "ADEKA", "ADK STAB PEP-36", "ADK STAB 3010", "ADK STAB" The trade names of HP-10" and "ADK STAB 2112" were purchased.

Specific examples of the phosphite-based compound include dimethyl-phenyl phosphite, di-t-butyl-phenyl phosphite, diphenyl-phenyl phosphite, and di-(4). -pentyl-phenyl)-phenylphosphite, bis-(2-t-butyl-phenyl)-phenylphosphite, bis-(2-methyl-3-pentyl-phenyl) -phenylphosphite, bis-(2-methyl-4-octyl-phenyl)-phenylphosphite, bis-(3-butyl-4-methyl-phenyl)-phenyl Phosphate ester, bis-(3-hexyl-4-ethyl-phenyl)-phenyl phosphite, bis-(2,4,6-trimethylphenyl)-phenyl phosphite, di-( 2,3-Dimethyl-4-ethyl-phenyl)-phenylphosphite, bis-(2,6-diethyl-3-butylphenyl)-phenylphosphite, di- (2,3-dipropyl-5-butylphenyl)-phenylphosphite, bis-(2,4,6-tri-t-butylphenyl)-phenylphosphite, bis ( 2,4-di-t-butyl-5-methylphenyl)biphenyl-4-yl-phosphite, bis(2,4-di-t-butyl-5-methylphenyl) -4'-(double (2,4-di-t- Butyl-5-methylphenoxy)phosphine)biphenyl-4-yl-phosphite, hydrazine (2,4-di-t-butyl-phenyl)- 4,4'-linked phenylenediphosphite, bismuth (2,5-di-t-butyl-phenyl)-4,4'-linked benzene diphosphite, bismuth (3,5-di -t-butyl-phenyl)-4,4'-linked phenylenediphosphite, bismuth (2,3,4-trimethylphenyl)-4,4'-linked benzene diphosphite , (2,3-dimethyl-5-ethyl-phenyl)-4,4'-linked benzene diphosphite, bismuth (2,3-dimethyl-4-propylphenyl) -4,4'-linked phenylenediphosphite, bismuth (2,3-dimethyl-5-t-butylphenyl)-4,4'-linked benzene diphosphite, bismuth (2 ,5-dimethyl-4-t-butylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,3-diethyl-5-methylphenyl)-4, 4'-linked phenylenediphosphite, bismuth (2,6-diethyl-4-methylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,4,5- Triethylphenyl)-4,4'-linked phenylenediphosphite, bismuth (2,6-diethyl-4-propylphenyl)-4,4'-linked phenyl bisphosphite , (2,5-diethyl-6-butylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,3-diethyl-5-t-butylphenyl) ) 4,4'-linked phenylenediphosphite, bismuth (2,5-diethyl-6-t-butylphenyl)-4,4'-linked benzene diphosphite, bismuth (2, 3-dipropyl-5-methylphenyl)-4,4'-linked phenylenediphosphite, hydrazine (2,6-dipropyl-4-methylphenyl)-4,4'- Benzene diphosphite, bismuth (2,6-dipropyl-5-ethylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,3-dipropyl-6 -butylphenyl)-4,4'-linked phenylenediphosphite, bismuth (2,6-dipropyl-5-butylphenyl)-4,4'-linked benzene diphosphite , (2,3-dibutyl-4-methylphenyl)-4,4'-linked benzene diphosphite, hydrazine (2,5-dibutyl-3-methylphenyl)- 4,4'-linked phenylenediphosphite, bismuth (2,6-dibutyl-4-methylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,4- Di-t-butyl-3-methylphenyl)-4,4'-linked phenylenediphosphite, bismuth (2,4-di-t-butyl-5-methylphenyl)-4 , 4'-coupling Phenyl bisphosphite, bismuth (2,4-di-t-butyl-6-methylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,5-di-t- Butyl-3-methylphenyl)-4,4'-linked phenylenediphosphite, hydrazine (2,5-di-t-butyl-4-methylphenyl)-4,4'- Benzene diphosphite, bismuth (2,5-di-t-butyl-6-methylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,6-di- T-butyl-3-methylphenyl)-4,4'-linked phenylenediphosphite, hydrazine (2,6-di-t-butyl-4-methylphenyl)-4,4 '-Derivative benzene diphosphite, bismuth (2,6-di-t-butyl-5-methylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,3- Dibutyl-4-ethylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,4-dibutyl-3-ethylphenyl)-4,4'-stretch Phenyl bisphosphite, bismuth (2,5-dibutyl-4-ethylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,4-di-t-butyl- 3-ethylphenyl)-4,4'-linked phenylenediphosphite, bismuth (2,4-di-t-butyl-5-ethylphenyl)-4,4'-coupling Diphosphite, bismuth (2,4-di-t-butyl-6-ethylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,5-di-t-butyl) 3-ethylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,5-di-t-butyl-4-ethylphenyl)-4,4'-linked Benzoyl phosphite, bismuth (2,5-di-t-butyl-6-ethylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,6-di-t -butyl-3-ethylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,6-di-t-butyl-4-ethylphenyl)-4,4' -co-phenylene phosphite, bismuth (2,6-di-t-butyl-5-ethylphenyl)-4,4'-linked benzene diphosphite, bismuth (2,3,4 -tributylphenyl)-4,4'-linked phenylenediphosphite, bismuth (2,4,6-tri-t-butylphenyl)-4,4'-linked phenylenediphosphite Ester and the like. Phosphorus compounds of the above type, for example, may be obtained by Ciba Specialty Chemicals Co., Ltd. as "IRGAFOS P-EPQ", and the chemical industry shares The company is purchased under the trade name "GSY-P101".

As the phosphorus-based compound useful in the present invention, a phosphite-based compound is preferred, and bis(2,4-di-t-butyl-phenyl)-4,4'-linked phenylenediphosphoric acid is also used. A 4,4'-linked benzene bisphosphite compound such as an ester is preferred, and a particularly preferred one is bis(2,4-di-t-butyl-5-methylphenyl)-4,4'-linked. Benzoyl phosphite.

(alkyl radical scavenger) The "alkyl radical scavenger" in the present invention is a compound which has a group which can rapidly react with an alkyl radical and which imparts a stable product which does not cause a subsequent reaction after reacting with an alkyl radical.

Preferred examples of the alkyl radical scavenger in the present invention include the compound represented by the above formula (1) and the compound represented by the above formula (2).

Hereinafter, specific examples of the compound represented by the above general formula (1) used in the present invention will be described, but the present invention is not limited thereto.

In the above general formula (1), R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, particularly preferably a hydrogen atom or a methyl group.

R ₂ and R ₃ each independently represent an alkyl group having 1 to 8 carbon atoms, and may have a linear chain structure, a branched structure or a ring structure. R ₂ and R _{3 are} preferably a structure represented by "*-C(CH ₃ ) ₂ -R'" containing a 4-stage carbon (* represents a linking moiety to an aromatic ring, and R' represents an alkyl group having 1 to 5 carbon atoms. .). R _{2 is more} preferably tert-butyl or tert-pentyl. R _{3 is more} preferably tert-butyl, tert-pentyl or tert-octyl.

The compound represented by the above general formula (1) is commercially available from Sumitomo Chemical Co., Ltd. under the trade names of "Sumilizer GM" and "Sumilizer GS".

Specific examples of the compound represented by the above general formula (1) are given below, but the present invention is not limited thereto.

Next, a specific example of the compound represented by the above general formula (2) used in the present invention will be described, but the present invention is not limited thereto.

In the general formula (2), R ₁₂ to R ₁₅ each independently represent a hydrogen atom or a substituent. R ₁₂ and R ₁₃ , R ₁₃ and R ₁₄ , or R ₁₄ and R ₁₅ may be bonded to each other to form a ring. R ₁₆ represents a hydrogen atom or a substituent, n represents an integer of 1 to 4, and when n is 1, R ₁₁ represents a substituent, and when n is an integer of 2 to 4, R ₁₁ represents a 2 to 4 valent linking group.

When R ₁₂ to R ₁₅ represent a substituent, the substituent is not particularly limited, and examples thereof include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group, and the like). Hexyl, octyl, dodecyl, trifluoromethyl, etc.), cycloalkyl (eg, cyclopentyl, cyclohexyl, etc.), aryl (eg, phenyl, naphthyl, etc.), guanamine (eg, , acetamino group, benzamidine, etc.), alkylthio (eg, methylthio, ethylthio, etc.), arylthio (eg, phenylthio, naphthylthio, etc.) Alkenyl (for example, vinyl, 2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3-butenyl, 4-hexyl) Alkenyl, cyclohexenyl, etc.), halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkynyl group (for example, propynyl group, etc.), heterocyclic group (for example, pyridyl group, thiazole) Alkylsulfonyl, alkylsulfonyl, etc. Alkyl sulfinyl (for example, methylsulfinyl, etc.), aromatic A sulfinyl group (for example, a phenylsulfinyl group, etc.), a phosphinium group, a fluorenyl group (for example, an ethyl sulfonyl group, a trimethylethyl fluorenyl group, a benzhydryl group, etc.), an aminomethyl fluorenyl group (for example) , amine carbonyl, methylamine carbonyl, dimethylamine carbonyl, butylamine carbonyl, cyclohexylamine carbonyl, aniline carbonyl, 2-pyridylamine carbonyl, etc.), amine sulfonyl (for example, amidoxime, methotrexate) Base, dimethylamine sulfonyl, butylamine sulfonyl, hexylamine sulfonyl, cyclohexylamine sulfonyl, octylamine sulfonyl, dodecylamine sulfonyl, aniline sulfonyl, naphthylamine Sulfonyl, 2-pyridylamine sulfonyl, etc.), sulfonylamino (eg, sulfonamide, benzenesulfonylamino, etc.), cyano, alkoxy (eg, methoxy, B) Oxyl, propoxy, etc.), aryloxy (e.g., phenoxy, naphthyloxy, etc.), heterocyclic oxy, decyloxy, decyloxy (e.g., ethoxylated, benzyloxy) Base, etc.), sulfonic acid group, salt of sulfonic acid, amine carbonyloxy group, amine group (for example, amine group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamine) Base, dodecylamine, etc.), anilino (for example, anilino, chloroaniline, Toluidine, anisidine, naphthylamino, 2-pyridylamino, etc.), imine, ureido (eg, methylureido, ethylureido, pentylurea, cyclohexylureido) , octylureido, dodecylureido, phenylureido, naphthylureido, 2-pyridylamine ureido, etc.), alkoxycarbonylamino (for example, methoxycarbonylamino, benzene) An oxycarbonylamino group, etc.), an alkoxycarbonyl group (for example, a methoxycarbonyl group, an ethoxycarbonyl group, a phenoxycarbonyl group, etc.), an aryloxycarbonyl group (for example, a phenoxycarbonyl group, etc.), a heterocyclic thio group. Each group such as a thiourea group, a carboxyl group, a carboxylic acid salt, a hydroxyl group, a hydrogenthio group, or a nitro group. These substituents may be substituted by the same substituents.

In the above general formula (2), R ₁₂ to R _{15 are} preferably a hydrogen atom or an alkyl group.

In the above general formula (2), R ₁₆ represents a hydrogen atom or a substituent, and the substituent represented by R ₁₆ may be the same as the substituent represented by R ₁₂ to R ₁₅ . In particular, it is preferred that R ₁₆ is a hydrogen atom.

In the above general formula (2), n represents an integer of 1 to 4, and when n represents 1, R ₁₁ represents a substituent, and examples of the substituent include the same substituents as those represented by R ₁₂ to R ₁₅ . When n is an integer of 2 to 4, R ₁₁ represents each corresponding 2 to 4 valent linking group.

When R ₁₁ represents a 2 to 4 valent linking group, examples of the divalent linking group include a divalent alkyl group which may have a substituent, a divalent aryl group which may have a substituent, an oxygen atom, a nitrogen atom, and sulfur. A combination of yellow atoms or their linking groups.

Examples of the trivalent linking group include a trivalent alkylene group which may have a substituent, a trivalent extended aryl group which may have a substituent, a nitrogen atom, or a combination of these linking groups, and as a tetravalent linking group, for example. A tetravalent alkylene group which may have a substituent, a tetravalent extended aryl group which may have a substituent, or a combination of these linking groups may be mentioned.

In the above general formula (2), n is preferably 1, and R _{11 in} this case is preferably a substituted or unsubstituted phenyl group, and examples of the substituent include an alkyl group having 1 to 18 carbon atoms and 1 carbon atom. The alkoxy group to 18 is more preferably an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms.

Although specific examples of the compound represented by the above general formula (2) of the present invention are given below, the present invention is not limited thereto.

(other antioxidants) Specific examples of other antioxidants include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl decyl 3,3-thiodipropionate. Ester, lauryl stearyl 3,3-thiodipropionate, pentaerythritol-indole (β-lauryl-thio-propionate), 3,9-bis(2-dodecylthioethyl) a sulfur compound such as -2,4,8,10-tetraoxaspiro[5,5]undecane. Sulfur compounds of the above type are commercially available, for example, from Sumitomo Chemical Co., Ltd. under the trade names "Sumilizer TPL-R" and "Sumilizer TP-D". Moreover, the 3,4-dihydro-2H-1-benzophenone described in JP-A 08-27508 can be mentioned. a pyran compound, a 3,3'-spirochromone compound, a 1,1-spiroxan compound, a morpholine, a thiomorpholine, a thiomorpholine oxide, a thiomorpholine dioxide, and a partial structure having An oxygen scavenger such as a piperazine skeleton compound or a dialkoxybenzene compound described in JP-A-3-174450. Some of the structure of these antioxidants may be part of the polymer, or regularly become a side chain of the polymer.

"Hindered Amine Light stabilizer" In the present invention, the deterioration preventing agent at the time of heat fusion of the film forming material, the external light exposed as a polarizing film protective film after the production, or the light deterioration preventing agent of the backlight of the liquid crystal display may be a hindered amine light stabilizer. (HALS) compound, which is a known compound, and examples thereof include 2, 2, 6 in columns 5 to 11 of the specification of U.S. Patent No. 4,619,956 and columns 3 to 5 of the specification of U.S. Patent No. 4,839,405. a 6-tetraalkylpiperidine compound, or an acid addition salt thereof or a complex of these with a metal compound.

Specific examples of the hindered amine light stabilizer include bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate and bis(2,2,6,6-tetramethyl). 4-piperidinyl) succinate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(N-octyloxy-2,2 ,6,6-tetramethyl-4-piperidinyl) sebacate, bis(N-benzyloxy-2,2,6,6-tetramethyl-4-piperidinyl)sebacate Ester, bis(N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl- 4-piperidinyl) 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-butylmalonate, bis(1-acrylinyl-2,2,6 , 6-four 4-(piperidinyl) 2,2-bis(3,5-di-t-butyl-4-hydroxybenzyl)-2-butylmalonate, bis(1,2,2, 6,6-pentamethyl-4-piperidinyl) sebacate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4-[3-(3,5 -di-t-butyl-4-hydroxyphenyl)propanoxy]-1-[2-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propenyloxy Ethyl]-2,2,6,6-tetramethylpiperidine, 2-methyl-2-(2,2,6,6-tetramethyl-4-piperidinyl)amine-N-( 2,2,6,6-tetramethyl-4-piperidyl)propanamide, hydrazine (2,2,6,6-tetramethyl-4-piperidinyl) 1,2,3,4- Butane tetracarboxylate, hydrazine (1,2,2,6,6-pentamethyl-4-piperidinyl) 1,2,3,4-butane tetracarboxylate, and the like.

Further, it may be a polymer type compound, and specific examples thereof include N,N',N",N'''-肆-[4,6-bis-[butyl-(N-methyl-2, 2,6,6-tetramethylpiperidin-4-yl)amine]-triazin-2-yl]-4,7-diazadecane-1,10-diamine, dibutylamine and 1, 3,5-triazine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexamethyldiamine and N-(2,2 , 6,6-tetramethyl-4-piperidyl)butylamine polycondensate, dibutylamine and 1,3,5-triazine with N,N'-bis(2,2,6,6-tetra Polycondensate of methyl-4-piperidinyl)butylamine, poly[{(1,1,3,3-tetramethylbutyl)amine-1,3,5-triazine-2,4-diyl }{(2,2,6,6-tetramethyl-4-piperidinyl)imide}hexamethyl{(2,2,6,6-tetramethyl-4-piperidinyl)imide }], 1,6-hexanediamine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl) and morpholine-2,4,6-trichloro-1 , 3,5-triazine polycondensate, poly[(6-morpholino-s-triazine-2,4-diyl)[(2,2,6,6-tetramethyl-4-piperidine) a piperazine ring such as an imine]-hexamethylene [[2,2,6,6-tetramethyl-4-piperidinyl)imide]] High molecular weight HALS with a complex combination of backbone; dimethyl succinate and 4-hydroxy- Polymer of 2,2,6,6-tetramethyl-1-piperidineethanol, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4 Mixed esterified product of piperidinol with 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane The piperidine ring is a compound in which an ester bond is bonded, but is not limited thereto.

Among them, the polycondensate of dibutylamine and 1,3,5-triazine with N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)butylamine {(1,1,3,3-tetramethylbutyl)amine-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4- Piperidinyl)imide}hexamethyl {{2,2,6,6-tetramethyl-4-piperidinyl)imide}], dimethyl succinate and 4-hydroxy-2,2, A polymer of 6,6-tetramethyl-1-piperidineethanol or the like, preferably having a number average molecular weight (Mn) of 2,000 to 5,000.

The hindered amine compound of the above type is commercially available, for example, from Ciba Specialty Chemicals under the trade names "TINUVIN 144" and "TINUVIN 770" and by ADEKA under the trade name "ADK STAB LA-52".

In the present invention, the hindered amine light stabilizer is preferably added in an amount of 0.1 to 10% by mass based on the mass of the cellulose ester of the present invention, and preferably added in an amount of 0.2 to 5% by mass, and 0.5 to 2% by mass. The amount is better. These can be used in combination of 2 or more types.

Acid Capture Agent The cellulose ester is preferably decomposed by acid in such a high-temperature environment that melt film formation, and the optical film of the present invention preferably contains an acid scavenger as a deterioration preventing agent. The useful acid scavenger of the present invention is not particularly limited as long as it can be reacted with an acid to inactivate the acid. Among them, a compound having an epoxy group described in the specification of U.S. Patent No. 4,137,201 is preferred. Epoxy compounds as such acid scavengers are known in the art field, and various diglycidyl ethers of polyethylene glycol, especially about 8 to 40 moles per 1 mole of polyethylene glycol. a polyethylene glycol such as ethylene oxide, a diglycidyl ether of glycerin or the like, a metal epoxy compound (for example, a vinyl chloride polymer composition, simultaneously with a vinyl chloride polymer composition) Used in the past, epoxidized ether condensation product, diglycidyl ether of bisphenol A (ie, 4,4'-dihydroxydiphenyldimethylmethane), epoxy group unsaturated Fatty acid esters (especially alkyl esters of 4 to 2 carbon atoms (for example, butyl epoxy stearate) of fatty acids of 2 to 22 carbon atoms), and various epoxylated long A composition of a chain fatty acid triglyceride or the like (for example, an epoxylated soybean oil, an epoxylated linseed oil, etc.) as a representative example of an epoxidized vegetable oil and other unsaturated natural oils (sometimes referred to as Epoxylated natural glycerides or unsaturated fatty acids, which typically contain from 12 to 22 carbon atoms. Further, as the epoxy group-containing epoxide resin compound to be sold, EPON 815C or another epoxidized ether oligomer condensation product can be used.

Further, examples of the acid scavenger other than the above-mentioned acid scavengers which can be used include an oxetane compound or an oxazoline compound, an organic acid salt of an alkaline earth metal or an acetamidineacetate complex, and JP-A-5-194788 Those recorded in paragraphs 68-105.

In the present invention, the acid scavenger is preferably added in an amount of 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and more preferably 0.5 to 2% by mass, based on the mass of the cellulose ester of the present invention. These can be used in combination of 2 or more types.

Further, the acid scavenger may be referred to as an acid scavenger, an acid scavenger, an acid collector, or the like, but may be used in the present invention without being distinguished by a different name.

Metal Inert Agent The metal inert agent is a compound which inactivates a metal ion by the action of a starter or a catalyst in the oxidation reaction, and examples thereof include an anthraquinone compound, a ruthenium oxalate compound, and a triazole compound, and examples thereof include, for example, N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propanyl]anthracene, 2-hydroxyethyl oxalate diamine, 2-hydroxy-N-( 1H-1,2,4-triazol-3-yl)benzoguanamine, N-(5-tert-butyl-2-ethoxyphenyl)-N'-(2-ethylphenyl) Oxalic acid amide and the like.

In the present invention, the metal inert agent is preferably added in an amount of 0.0002 to 2% by mass, more preferably 0.0005 to 2% by mass, and preferably 0.001 to 1% by mass based on the mass of the cellulose ester of the present invention. The amount is better. These can be used in combination of 2 or more types.

Plasticizer In the optical film formed by the melt casting of the present invention, at least one of plasticizers must be added to the film forming material.

The plasticizer is an additive which is generally added to a polymer to improve the fragility or has a softening effect. In the present invention, an additive which lowers the melting temperature of the film forming material or a film forming material at the same temperature can be used. Viscosity additive. By lowering the melting temperature or lowering Since the melt viscosity can suppress deterioration of the cellulose ester in the melting process, the material having such an effect only in the present invention can be used as a plasticizer, and is not particularly limited. Such a melting point reduction effect. The viscosity is reduced, and if the plasticizer to be added is a plasticizer having a melting point lower than the glass transition temperature of the cellulose ester or a glass transition temperature, a larger effect is easily obtained.

Further, by adding a plasticizer, the mechanical properties of the cellulose ester film can be improved, and the effects of the tensile strength, the water absorption resistance, and the water permeability can be improved. Therefore, it is more preferable to use a material having these effects as a plasticizer.

Further, the plasticizer has an effect of suppressing the deterioration of the thermal melting process of the cellulose ester as described above, and the effect depends on the physical effect, and is not caused by the chemical effect, and therefore is not classified as a deterioration preventing agent in the present invention. .

In order to satisfy the above conditions, examples of the plasticizer used in the present invention include a phosphate ester plasticizer and a polyol ester plasticizer (a glycol ester plasticizer, a glyceride plasticizer, and a diglyceride plasticizer). Agents, etc.), polycarboxylate-based plasticizers, carbohydrate ester-based plasticizers, polymer plasticizers, and the like. Among them, a polyol ester-based plasticizer and a polycarboxylic acid ester-based plasticizer are preferred, and a polyol ester-based plasticizer is more preferred. Further, the plasticizer may be a liquid or a solid, and it is preferred that the composition is colorless within the specification. The amount added is only for optical properties. The mechanical properties may be adversely affected, and the blending amount may be appropriately selected within the range not impairing the object of the present invention. For the quality of the cellulose ester of the present invention, it is preferred to contain cellulose in an amount of 1 to 25% by mass. Ester film. When the amount is less than 1% by mass, the planarity improving effect cannot be obtained, and if it is more than 25% by mass, external leakage is likely to occur, and the stability of the film with time is lowered. good. More preferably, it is a cellulose ester film containing 3 to 20% by mass of a plasticizer, and more preferably a cellulose ester film containing 5 to 15% by mass.

Specific examples of the plasticizer used in the present invention will be described below, but the present invention is not limited thereto.

In the present invention, an ester-based plasticizer composed of a polyhydric alcohol and a monocarboxylic acid, and an ester-based plasticizer composed of a polyvalent carboxylic acid and a monohydric alcohol have a higher affinity with a cellulose ester, and are preferably a polyol. The ester-based plasticizer made of a monocarboxylic acid has a higher affinity with a cellulose ester, which is particularly preferable.

Further, a polyol ester-based plasticizer, that is, a compound having a plurality of hydroxyl groups in one molecule and a compound condensed with a monovalent organic acid is called a polyol ester-based plasticizer, and a polycarboxylic acid ester-based plasticizer is a molecule. A compound having a complex carboxylic acid group and a compound condensed with a plurality of monohydric alcohols or phenols is called a polycarboxylate type plasticizer.

Examples of the raw material polyol which is preferably an ester-based plasticizer in the present invention include, for example, the following, but the present invention is not limited thereto.

Examples thereof include ribitol, arabitol, ethylene glycol, glycerin, diglycerin, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, and three Propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1 ,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, tetramethylethylene glycol, sorbitol, trimethylol Propane, ditrimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, xylitol sugar, and the like. In particular, ethylene glycol, glycerin or trimethylolpropane is preferred.

Further, examples of preferred organic acids include acetic acid, propionic acid, and butyl Acid, isobutyric acid, trimethylacetic acid, acrylic acid, methacrylic acid, cyclohexylcarboxylic acid, benzoic acid, anisic acid, 3,4,5-trimethoxybenzoic acid, toluic acid, tert-butylbenzoic acid, Naphthoic acid, pyroline acid, etc., but an unsaturated carboxylic acid having a higher effect of reducing the moisture permeability of the cellulose ester, for example, a polyol ester formed by an aromatic carboxylic acid

The acid used for the polyol ester may be one type or two or more types. Further, the OH group in the polyol may be all esterified, or the OH group may be directly left in part.

Examples of the glycol ester-based plasticizer which is one of the polyol esters include ethylene glycol alkyl ester plasticizers such as ethylene glycol diacetate and ethylene glycol dibutyrate, and ethylene glycol II. Ethylene glycol cycloalkyl ester plasticizers such as cyclopropyl carboxylate and ethylene glycol bicyclohexacarboxylate, ethylene glycol dibenzoate, ethylene glycol di 4-methylbenzoate, etc. Ethylene glycol aryl ester plasticizer. These alkylating groups, cycloalkylating groups, and arylating groups may be the same or different and may be further substituted. Further, it may be a mixture of an alkyl group, a cycloalkyl group or an aryl group, or these substituents may be bonded to each other by a covalent bond. The ethylene glycol moiety may be further substituted, and the partial structure of the ethylene glycol ester may be a part of the polymer, or may be a regular side chain, and may be introduced into an antioxidant, an acid sweeping agent, and a UV resistant agent. a part of the molecular structure of additives such as agents.

Examples of the glyceride-based plasticizer which is one of the polyol esters include glyceryl triglyceride, glyceryl tributyrate, glyceryl diacetate octanoate, and glycerol oleate propionate. Glyceryl aryl esters such as esters, glycerol tricyclopropyl carboxylate, glycerol tricyclohexyl carboxylate, glycerol tribenzoate, glycerol 4-methyl benzoate, tetraethyl hydrazine Diglycerin, two Tripropionate, diglycerin acetate trioctanoate, diglycerin tetralaurate, diglyceryl alkyl ester, diglyceryl tetracyclobutyl carboxylate, diglyceryl tetracyclopentyl carboxylate, etc. Diglycerin aryl esters such as diglyceryl cycloalkyl ester, diglycerin tetrabenzoate, diglycerin 3-methylbenzoate, and the like. These alkylating groups, cycloalkyl carboxylate groups, and arylating groups may be the same or different and may be substituted. Further, it may be a mixture of an alkyl group, a cycloalkyl carboxylate group, or an aryl group, or these substituents may be covalently bonded to each other. Moreover, the glycerin and the diglycerin moiety may be substituted, and the partial structure of the glyceride or the diglyceride may be a part of the polymer, or may be a side chain regularly, and may be introduced into an antioxidant, an acid sweeping agent, and an anti-oxidant. A part of the molecular structure of an additive such as an ultraviolet agent.

Specific examples of the other polyol ester-based plasticizers include the polyol ester-based plasticizers described in paragraphs 30 to 33 of JP-A-2003-12823.

These alkylating groups, cycloalkyl carboxylate groups, and arylating groups may be the same or different and may be further substituted. Further, it may be a mixture of an alkyl group, a cycloalkyl carboxylate group, or an aryl group, or these substituents may be covalently bonded to each other. Further, the polyol portion may be further substituted, and the partial structure of the polyol may be a part of the polymer, or may be a regular side chain, and may be introduced into an antioxidant, an acid sweeping agent, an anti-UV agent, or the like. A part of the molecular structure of the additive.

Among the ester-based plasticizers of the above-mentioned polyol and monocarboxylic acid, an alkyl polyol aryl ester is preferred, and specific examples thereof include the above-mentioned ethylene glycol dibenzoate, glycerin tribenzoate, and The exemplified compound 16 described in Paragraph 31 of JP-A-2003-12823.

Specific examples of the dicarboxylic acid ester-based plasticizer which is one of the polycarboxylic acid esters include an alkane such as di-dodecylmalonate, dioctyl adipate or dibutyl sebacate. Alkyl dicarboxylic acid cycloalkyl ester-based plasticizer, dicyclopentyl succinate, dicyclohexyl adipate, etc., alkyl dicarboxylic acid cycloalkyl ester plasticizer, diphenyl succinate, di 4 -alkyl carboxylic acid aryl ester-based plasticizer such as methyl phenyl glutarate, dihexyl-1,4-cyclohexyl dicarboxylate, dimercaptobicyclo, [2.2.1] heptane - a cycloalkyldicarboxylic acid alkyl ester such as a 2,3-dicarboxylate plasticizer, dicyclohexyl-1,2-cyclobutanedicarboxylate, dicyclopropyl-1,2-cyclohexyl Cycloalkyl dicarboxylic acid cycloalkyl ester plasticizer such as carboxylate, diphenyl-1,1-cyclopropyldicarboxylate, di-2-naphthyl-1,4-cyclohexyl dicarboxylic acid Cycloalkyl dicarboxylates such as esters, plasticizers, diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate Alkyl aryl dicarboxylates such as diformate and di-2-ethylhexyl phthalate Aryl dicarboxylic acid cycloalkyl ester plasticizer such as plasticizer, dicyclopropyl phthalate or dicyclohexyl phthalate, diphenyl phthalate, di 4- An aryl dicarboxylate aryl ester such as methylphenyl phthalate, a glycolate such as butyl decyl butyl glycol ester or ethyl decyl ethyl glycol ester It is a plasticizer, a citric acid plasticizer such as acetyl citrate trimethyl, ethionyl triethyl citrate or acetyl citrate tributyl. These alkoxy groups, cycloalkoxy groups may be the same or different, may be monosubstituted, or their substituents may be further substituted. The alkyl group, the cycloalkyl group may be mixed, or these substituents may be bonded to each other by a covalent bond. Further, the aromatic ring of the phthalic acid may be substituted, or may be a polymer such as a dimer, a trimer or a tetramer. The partial structure of the benzoic acid ester may be part of the polymer, or regularly The side chain of the polymer can also be introduced into a part of the molecular structure of an additive such as an antioxidant, an acid sweeping agent, or an ultraviolet ray inhibitor.

Specific examples of the other polycarboxylic acid ester-based plasticizer include alkyl groups such as tri-dodecyltricarboxylate and tributyl-meso-butane-1,2,3,4-tetracarboxylate. A polyalkylene carboxylate-based plasticizer, a tricyclohexyltricarboxylate, a tricyclopropyl-2-hydroxy-1,2,3-propane tricarboxylate or the like, an alkyl polycarboxylic acid cycloalkyl ester Alkyl polycarboxylic acid such as plasticizer, triphenyl 2-hydroxy-1,2,3-propane tricarboxylate, tetrakis 3-methylphenyltetrahydrofuran-2,3,4,5-tetracarboxylate Aryl ester-based plasticizers, cyclohexenes such as tetrahexyl-1,2,3,4-cyclobutanetetracarboxylate, tetrabutyl-1,2,3,4-cyclopentanetetracarboxylate Alkyl carboxylate-based plasticizer, cycloalkyl-1,2,3,4-cyclobutanetetracarboxylate, cycloalkyl group such as tricyclohexyl-1,3,5-cyclohexyltricarboxylate Polycarboxylic acid cycloalkyl ester plasticizer, triphenyl-1,3,5-cyclohexyltricarboxylate, hexa-methylphenyl-1,2,3,4,5,6-cyclohexyl Cycloalkyl polycarboxylate aryl esters such as hexacarboxylates, plasticizers, tris(dodecylbenzene)-1,2,4-tricarboxylate, tetraoctylbenzene-1,2,4,5 - aryl group such as tetracarboxylic acid ester Alkyl carboxylic acid alkyl ester-based plasticizer, tricyclopentylbenzene-1,3,5-tricarboxylate, tetracyclohexylbenzene-1,2,3,5-tetracarboxylic acid ester, etc. Cycloalkyl ester-based plasticizer triphenylbenzene-1,3,5-tetracarboxylate, hexa-methylphenylbenzene-1,2,3,4,5,6-hexacarboxylate The polyvalent carboxylic acid aryl ester is a plasticizer. These alkoxy groups and cycloalkoxy groups may be the same or different, may be substituted, or the substituents may be further substituted. The alkyl group, the cycloalkyl group may be mixed, or these substituents may be bonded to each other by a covalent bond. Further, the aromatic ring of the phthalic acid may be substituted, or may be a polymer such as a dimer, a trimer or a tetramer. The partial structure of the benzoic acid ester may be part of the polymer, Alternatively, it may be a side chain of the polymer, or may be introduced into a part of the molecular structure of an additive such as an antioxidant, an acid sweeping agent, or an ultraviolet ray inhibitor.

Among the ester-based plasticizers of the above polyvalent carboxylic acid and monohydric alcohol, an alkyl dicarboxylate alkyl ester is preferred, and specific examples thereof include the above dioctyl adipate.

The other plasticizer used in the present invention may, for example, be a phosphate ester plasticizer, a carbohydrate ester plasticizer, a polymer plasticizer or the like.

Specific examples of the phosphate-based plasticizer include alkyl phosphate such as triethylphosphonium phosphate and tributyl phosphate, cycloalkyl phosphate such as tricyclopentyl phosphate and cyclohexyl phosphate, and triphenyl group. Phosphate, tricresyl phosphate, cresyl phenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, trinaphthyl phosphate An aryl phosphate such as ester, trimethylphenyl phosphate or o-biphenyl phosphate. These substituents may be the same or different and may be substituted. Further, it may be a mixture of an alkyl group, a cycloalkyl group, and an aryl group, and the substituents may be bonded to each other by a covalent bond.

Further, an ethyl bis(dimethyl phosphate), a butyl bis(diethyl phosphate), an alkyl bis(dialkyl phosphate), an ethyl bis(diphenyl phosphate), Propyl bis(dinaphthyl phosphate), such as alkyl bis(diaryl phosphate), phenyl bis(dibutyl phosphate), diphenyl bis(dioctyl phosphate) Phosphate such as aryl bis(dialkyl phosphate), phenyl bis(diphenyl phosphate), and naphthyl bis(xyl phosphate) such as aryl bis(diaryl phosphate). These substituents may be the same or different and may be substituted. Further, it may be a mixture of an alkyl group, a cycloalkyl group, and an aryl group, and the substituents may be bonded to each other by a covalent bond.

And the partial structure of the phosphate ester may be part of the polymer, or may be Then, it becomes a side chain and can be introduced into a part of the molecular structure of an additive such as an antioxidant, an acid sweeping agent, or an ultraviolet ray inhibitor. Among the above compounds, an aryl phosphate or an aryl bis(diaryl phosphate) is preferred, and specifically, a triphenyl phosphate or a phenyl bis(diphenyl phosphate) is preferred.

Next, a description will be given of a carbohydrate ester plasticizer. The carbohydrate is a monosaccharide, disaccharide or trisaccharide in which the sugar is in the form of pyranose or furanose (6-membered ring or 5-membered ring). Non-limiting examples of the carbohydrate include glucose, sucrose, lactose, cellobiose, mannose, xylose, ribose, galactose, arabinose, fructose, sorbose, cellotriose, and raffinose. The carbohydrate ester is an aliphatic carboxylic acid ester of a carbohydrate or an aromatic carboxylic acid ester, which is obtained by dehydration condensation of a hydroxyl group of a carbohydrate with a carboxylic acid to form an ester compound. Examples of the aliphatic carboxylic acid include acetic acid and propionic acid. Examples of the aromatic carboxylic acid include benzoic acid, toluic acid, and anisic acid. The carbohydrate has a number of hydroxyl groups for the species, and a portion of the hydroxyl group can be reacted with the carboxylic acid to form an ester compound, or all of the hydroxyl group can be reacted with the carboxylic acid to form an ester compound. In the present invention, it is preferred that all of the hydroxyl groups are reacted with a carboxylic acid to form an ester compound.

Specific examples of the carbohydrate ester-based plasticizer include glucose pentaacetate, glucose pentapropionate, glucose pentabutyrate, sucrose octaacetate, and sucrose octabenzoate, among which sucrose is used. Octadecyl acetate, sucrose octabenzoate is more preferred, and sucrose octabenzoate is particularly preferred. Carbohydrate ester plasticizers of the above type are commercially available, for example, from the first industrial pharmaceutical company under the trade names "Monopet SB" and "Monopet SOA".

Specific examples of the polymer plasticizer include aliphatic hydrocarbon polymers, Alicyclic hydrocarbon polymer, polyethyl acrylate, polymethyl methacrylate, copolymer of methyl methacrylate and 2-hydroxyethyl methacrylate, methyl methacrylate and methyl acrylate and methyl Acrylic polymer such as 2-hydroxyethyl acrylate copolymer, vinyl polymer such as polyethylene isobutyl ether or poly N-vinylpyrrolidone, styrene polymerization such as polystyrene or poly-4-hydroxystyrene Polyethers such as polybutylene succinate, polyethylene terephthalate, polyethylene naphthalate, polyethers such as polyethylene oxide and polypropylene oxide, polyamines, polyurethanes , polyurea, etc. The number average molecular weight is preferably from 1,000 to 500,000, particularly preferably from 5,000 to 200,000. The volatility below 1000 causes problems, and if it exceeds 500,000, the plasticizing ability is lowered, which adversely affects the mechanical properties of the cellulose ester film. These polymer plasticizers may be a single polymer of one repeating unit or a copolymer of a plurality of repeating structures. Further, two or more kinds of the above polymers may be used in combination.

In the cellulose ester film of the present invention, an ester-based plasticizer composed of a polyhydric alcohol and a monovalent carboxylic acid, an ester-based plasticizer composed of a polyvalent carboxylic acid and a monohydric alcohol is preferably contained in an amount of 1 to 25% by mass. Use a plasticizer other than this.

In the cellulose ester film of the present invention, an ester-based plasticizer composed of a polyhydric alcohol and a monocarboxylic acid is more preferable, but an ester-based plasticizer composed of a trivalent or higher alcohol and a monovalent carboxylic acid is used for the cellulose ester. The compatibility is high, and the addition system is characterized by a high addition rate, and even if other plasticizers or additives are used in combination, no external leakage occurs, and it is preferable to use other kinds of plasticizers or additives as needed.

Anti-UV Agent In the present invention, since the film forming material further contains an ultraviolet ray-resistant agent, durability can be improved. The ultraviolet ray absorbing agent is excellent in the absorption of ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of ultraviolet rays by a polarizer or a display device, and the visible light having a wavelength of 400 nm or more is less absorbed from the viewpoint of liquid crystal display properties. It is better. Examples of the ultraviolet ray-resistant agent used in the present invention include an oxybenzophenone-based compound, a benzotriazole-based compound, a salicylate-based compound, a benzophenone-based compound, and a cyanoacrylate-based compound. A nickel phenoxy compound or a triazine compound, a benzophenone compound or a benzotriazole compound or a triazine compound having less coloration is preferred. Further, the polymer anti-UV agent described in JP-A-H05-182621, JP-A-H06-A No. Hei.

Specific examples of the benzotriazole-based compound include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 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"-tetrahydro酞醯iminomethyl)-5'-methylphenyl)benzotriazole, 2,2-extended methyl bis(4-(1,1,3,3-tetramethylbutyl)-6- (2H-benzotriazol-2-yl)phenol), 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2- (2'-Hydroxy-3'-tert-butyl-5'-(2-octyloxycarbonylethyl)-phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3' -(1-methyl-1-phenylethyl -5'-(1,1,3,3-tetramethylbutyl)-phenyl)benzotriazole, 2-(2H-benzotriazol-2-yl)-6- (straight chain and Side-locked dodecyl)-4-methylphenol, octyl-3-[3-tert-butyl-4-hydroxy-5-(chloro-2H-benzotriazol-2-yl)phenyl] Mixture of propionate with 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propanoate Etc., but not limited to this.

Further, as a commercial product, TINUVIN 326, TINUVIN 109, TINUVIN 171, TINUVIN 900, TINUVIN 928, TINUVIN 360 (all manufactured by Ciba Specialty Chemicals Co., Ltd.), LA31 (made by Adeka Co., Ltd.), Sumisorb 250 (manufactured by Sumitomo Chemical Co., Ltd.), and RUVA-100 (Daichi Chemical Co., Ltd.) are mentioned. system).

Specific examples of the benzophenone-based compound include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and 2-hydroxy-4-methyl. Oxy-5-sulfobenzophenone, bis(2-methoxy-4-hydroxy-5-benzimidylphenylmethane), and the like, but is not limited thereto.

The anti-UV agent in the present invention is preferably a benzotriazole-based compound.

In the present invention, the amount of the cellulose ester of the present invention is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and more preferably 0.5 to 3% by mass. These can be used in combination of 2 or more types.

Further, the benzotriazole structure or the triazine structure may be a part of the polymer, or a side chain which regularly becomes a polymer, or a molecular structure which is introduced into other additives such as a plasticizer, an antioxidant, an acid sweeping agent, and the like. Part of it.

The ultraviolet ray absorbing polymer which is known in the art is not particularly limited, and for example, a polymerization of RUVA-93 (manufactured by Otsuka Chemical Co., Ltd.) is separately exemplified. And a polymer copolymerized with RUVA-93 and other monomers. Specific examples thereof include PUVA-30M in which RUVA-93 and methyl methacrylate are copolymerized at a ratio (mass ratio) of 3:7, and PUVA-copolymerized at a ratio (mass ratio) of 5:5. 50M and so on. Further, a polymer or the like described in JP-A-2003-113317 can be mentioned.

Other Additives In the present invention, the cellulose ester may contain various additives other than the deterioration preventing agent, the plasticizer or the ultraviolet ray inhibitor. For example, an inorganic compound such as a matting agent, a filler, cerium oxide or cerium salt, a dye, a pigment, a phosphor, a dichroic dye, a retention controlling agent, a refractive index adjusting agent, a gas permeation inhibitor, and an antibacterial agent may be mentioned. Agent, biodegradability imparting agent, and the like. Further, it is only necessary to have the above functions, and it is also possible to use an additive which is not classified.

As a method of containing these additives in a cellulose ester, each material may be directly mixed in the form of a solid or a liquid, heated and melted, and then kneaded into a uniform melt, followed by casting to form an optical film, or in advance. After all the materials are dissolved in a uniform solution using a solvent or the like, the solvent is removed to form a mixture of the additive and the cellulose ester, which is heated and melted and cast to form an optical film.

(matting agent) A matting agent may be added to the film of the present invention in order to impart a lubricity or an optical or mechanical function. Examples of the matting agent include fine particles of an inorganic compound or fine particles of an organic compound.

The shape of the matting agent may preferably be a spherical shape, a rod shape, a needle shape, a layer shape, a flat shape or the like. Examples of the matting agent include cerium dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, clay, talc, calcined calcium citrate, calcium citrate hydrate, aluminum citrate, magnesium citrate, calcium phosphate, and the like. Inorganic fine particles such as metal oxides, phosphates, citrates, and carbonates or crosslinked polymer fine particles. Among them, cerium oxide can reduce the fog value of the film, so it is preferable. These fine particles can be surface-treated by an organic substance, thereby lowering the haze value of the film.

The surface treatment may preferably be carried out with a halogenated alkane, an alkoxydecane, a hydrazine nitrogen, a decane or the like. The larger the average particle diameter of the fine particles, the larger the smoothness effect, and conversely, the smaller the average particle diameter, the more excellent the transparency. Further, the average particle diameter of the primary particles of the fine particles is in the range of 0.01 to 1.0 μm. The average particle diameter of the primary particles of the preferred fine particles is preferably 5 to 50 nm, more preferably 7 to 14 nm. It is preferred that the fine particles form an unevenness of 0.01 to 1.0 μm on the surface of the cellulose ester film.

Examples of the fine particles of cerium oxide include Japanese AEROSIL (AEROSIL) 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, and NAX50, which are manufactured by Japan AEROSIL Co., Ltd. KE-P10, KE-P30, KE-P100, KE-P150, etc., preferably AEROSIL200V, R972V, NAX50, KE-P30, KE-P100. These fine particles may be used in combination of two or more kinds.

When two or more types are used together, they can be mixed at any ratio. Fine particles having an average particle diameter or material, such as AEROSIL 200V and R972V, can be used in a mass ratio of 0.1:99.9 to 99.9:0.1.

The method of adding these matting agents is preferably carried out by kneading or the like. Further, as another embodiment, a matting agent previously dispersed in a solvent and a cellulose ester and/or a plasticizer and/or an antioxidant and/or an ultraviolet ray preventive agent are mixed and dispersed, and then the solvent is volatilized or precipitated to obtain a solid matter. When this is used in the production process of the cellulose ester melt, it is preferred to uniformly disperse the matting agent in the cellulose ester.

To improve the mechanical, electrical, and optical properties of the film, the above matting agent may be added.

Further, by adding these fine particles, the smoothness of the obtained film can be improved, but the haze value is increased after the addition, so the content is preferably 0.001 to 5% by mass, more preferably 0.005 to 1% by mass, most preferably 0.01 to 0.5. quality%.

Further, as the film of the present invention, when the haze value exceeds 1.0%, the optical material is affected, and the haze value is preferably less than 1.0%, more preferably less than 0.5%. The haze value can be measured in accordance with JIS-K7136.

In the storage or film formation step of the above-mentioned film forming material, a deterioration reaction caused by oxygen in the air may be concurrently generated. At this time, the stability of the above-mentioned additives can be combined with the reduction of the oxygen concentration in the air to realize the present invention. In the prior art, nitrogen or argon is used as the inert gas, degassing operation under reduced pressure to vacuum, and operation in a closed environment. At least one of the three methods may be used in combination with the above additive. By reducing the probability of contact between the film forming material and oxygen in the air, deterioration of the material can be suppressed, which is advantageous for achieving the object of the present invention.

Optical Film Next, the optical film of the present invention will be described in detail.

The optical film of the present invention is a functional film used for various display devices such as a liquid crystal display, a plasma display, and an organic EL display, and is specifically a polarizing plate protective film, a retardation film, an antireflection film, and a brightness enhancement film for a liquid crystal display device. , an optically-coated film such as a hard coat film, an anti-glare film, an antistatic film, and an enlarged viewing angle.

In the optical film of the present invention, the cellulose ester resin, the cellulose ether resin, and the vinyl resin (which also contain a polyvinyl acetate resin or a polyvinyl alcohol resin) which are not related to the present invention may be contained in addition to the cellulose ester of the present invention. Olefin-based resin (norbornene-based resin, monocyclic cyclic olefin resin, cyclic conjugated diene resin, vinyl alicyclic hydrocarbon resin, etc.), polyester resin (aromatic polyester) An aliphatic polyester or a copolymer containing the same, an acrylic resin (including a copolymer), a polycarbonate resin, a polystyrene resin, a polyfluorene resin, a polyarylate resin, or the like. The content of the resin other than the cellulose ester is preferably from 0.1 to 30% by mass.

As the optical film of the present invention, a polarizing plate protective film, a retardation film, an optical compensation film can be used, and in particular, a polarizing plate can be used to protect the film.

Melt Casting Method The optical film of the present invention can be produced by melt casting as described above. The solvent used in the solution casting method (for example, methylene chloride or the like) can be classified into a melt extrusion molding method, a pressure molding method, an expansion method, or the like by a molding method of melt casting by heating and melting. Injection molding method, blow molding method, extension molding method, and the like. They want to get mechanical strength and surface finish A good polarizing plate protective film such as a degree is preferably a melt extrusion molding method.

The film forming material is required to have little or no volatile component in the melting and film forming steps. This is foaming when heated and melted, which can reduce or avoid defects in the inside of the film or planarity deterioration of the surface of the film.

The content of the volatile component in the film formation material at the time of melting is 1% by mass or less, preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and most preferably 0.1% by mass. In the present invention, a differential thermal weight measuring device (TG/DTA200 manufactured by SEIKO Electronics Co., Ltd.) is used to obtain a heating loss of 30 ° C to a temperature corresponding to the melt flow delay, and this amount is used as the content of the volatile component.

The film forming material to be used is preferably a volatile component which represents the moisture or the solvent, and is removed before or during the film formation. As the removal method, a known drying method can be applied, and a heating method, a pressure reduction method, a heating and pressure reduction method, or the like can be applied, and it can be carried out in the air or in an atmosphere in which nitrogen is selected as an inert gas. When these known drying methods are carried out, the quality of the film is better when it is carried out in a temperature region where the film forming material is not decomposed.

When drying is carried out before the film formation, the generation of the volatile component can be reduced, and the cellulose ester alone or the cellulose ester and the film forming material can be divided into at least one kind of mixture or a mixture other than the cellulose ester and then dried. The drying temperature is preferably 70 ° C or more. When a material having a glass transition temperature exists in the dried material, when the heating is performed at a drying temperature higher than the glass transition temperature, the material is melted and difficult to handle, so that the drying temperature is preferably at or below the glass transition temperature. When the plural substance has a glass transition temperature, it is based on the glass transition temperature at which the glass transition temperature is low. Preferably 70 ° C Upper, (glass transition temperature - 5) ° C or less, more preferably 110 ° C or more, (glass transition temperature - 20) ° C or less. The drying time is preferably from 0.5 to 24 hours, more preferably from 1 to 18 hours, and most preferably from 1.5 to 12 hours. If the drying temperature is too low, the removal rate of the volatile component becomes low, and the time required for drying is too long. Further, the drying step may be carried out in two or more stages. For example, the drying step may include a preliminary drying step of storing the material, and a pre-drying step performed between before and after the film formation.

(melt extrusion molding method) Hereinafter, a method for producing the cellulose ester film of the present invention will be described by taking a melt extrusion molding method as an example.

Fig. 1 is a schematic flow chart showing the overall configuration of a device for producing a cellulose ester film according to the present invention, and Fig. 2 is an enlarged view showing a portion from a casting die to a cooling roll.

1 and 2, the cellulose ester film of the present invention is produced by mixing a material such as a cellulose ester resin, and then extruding the film from the casting die 4 to the first cooling roll 5 using the extruder 1. In addition to the first cooling roll 5, a total of three cooling rolls of the second cooling roll 7 and the third cooling roll 8 are sequentially externally attached, and after cooling and solidifying, the film 10 is formed. The film 10 which has been peeled off by the peeling roller 9 is then stretched by the extension device 12 to extend the both ends of the film in the width direction, and then taken up by the winding device 16. Further, a contact roll 6 for holding the molten film on the surface of the first cooling roll 5 is provided. The contact roller 6 has a surface with elasticity, and forms a clip with the first cooling roller 5. The contact roller 6 will be described in detail later.

In the method for producing a cellulose ester film of the present invention, the conditions of melt extrusion can be carried out under the same conditions as those used for other thermoplastic resins such as polyester. It is preferred that the material is dried beforehand. The water is dried to 1000 ppm or less, preferably 200 ppm or less, by a vacuum or a vacuum dryer or a dehumidifying hot air dryer.

For example, the cellulose ester-based resin which is dried by hot air or under vacuum or under reduced pressure is melted at a pressure of 200 to 300 ° C using an extruder, and is filtered by a blade type filter 2 or the like to remove foreign matter.

When the feed hopper (not shown) is introduced into the extruder 1, it is preferable to prevent oxidative decomposition or the like under vacuum or under reduced pressure or in an inert gas atmosphere.

When an additive such as a plasticizer is not previously mixed, it can be kneaded on the way of the extruder. In order to be uniformly added, it is preferred to use a mixing device such as a static agitator 3.

In the present invention, it is preferred that the cellulose resin and an additive such as a deterioration preventive agent which are necessary to be added are mixed before melting. It is preferred that the cellulose resin and the additive are mixed before heating. The mixing is carried out using a mixer or the like, and mixing may be carried out during the preparation of the cellulose resin as described above. When a mixer is used, a general mixer such as a V-type mixer, a conical screw type mixer, a horizontal cylinder type mixer, a Henschel mixer, or a spiral belt mixer can be used.

After mixing the film constituting material as described above, the mixture is directly melted by using the extruder 1 to form a film. However, once the film constituting material is pelletized, the granules can be melted by the extruder 1 to form a film. Further, when the film constituent material contains a plurality of materials having different melting points, only the material having a lower melting point is melted at a temperature to produce a so-called rice-like semi-melt. After the semi-melt is put into the extruder 1, a film can also be formed. When a material which is easily thermally decomposed is contained in the film constituent material, a method of directly forming a film without producing particles or a method of forming a film after the above-described rice-like semi-molten is preferable for the purpose of reducing the number of times of melting.

The extruder 1 can use various commercially available extruders, but it is preferable to use a melt-kneading extruder, and a single-axis extruder or a 2-axis extruder can be used. When the film constituting material is not formed directly under the granules, since it is necessary to have a proper kneading degree, it is preferable to use a two-axis extruder, and the uniaxial extruder may be changed to a Maddock type by Mixing screws such as Unimelt and Dulmage can be used for moderate mixing. When a pellet or a rice-like semi-molten is used as the film constituent material, a uniaxial extruder or a two-axis extruder can be used.

The cooling step in the extruder 1 and after the extrusion is preferably carried out by replacing with an inert gas such as nitrogen gas or by reducing the concentration of oxygen by pressure reduction.

The melting temperature of the film constituent material in the extruder 1 is generally higher than the Tg of the glass transition temperature Tg of the film depending on the viscosity or the amount of the film constituent material, the thickness of the produced sheet, and the like. Tg + 130 ° C or less, preferably Tg + 10 ° C or more and Tg + 120 ° C or less.

The temperature at the time of melt extrusion of the present invention is preferably in the range of 200 ° C to 270 ° C, more preferably in the range of 230 to 260 ° C.

The melt viscosity at the time of extrusion is 1~10000Pa. s, preferably 10~1000Pa. s. Moreover, the residence time of the film constituent material in the extruder 1 is preferably shorter, within 5 minutes, preferably within 3 minutes, preferably within 2 minutes. . The residence time is determined by the type of the extruder 1 and the extrusion conditions, but it can be shortened by adjusting the supply amount of the material, the L/D, the number of screw revolutions, the groove depth of the screw, and the like.

The screw shape or the number of revolutions of the extruder 1 can be appropriately selected depending on the viscosity or discharge amount of the film constituent material. In the present invention, the cutting speed of the extruder 1 is from 1/sec to 10000/sec, preferably from 5/sec to 1000/sec, more preferably from 10/sec to 100/sec.

The extruder 1 used in the present invention is generally commercially available in the form of a plastic molding machine.

The film constituent material extruded from the extruder 1 is sent to the casting mold 4, and the crack of the self-casting mold 4 is extruded in a film form. The casting mold 4 is not particularly limited as long as it is a user who manufactures a sheet or a film. As the material of the casting mold 4, a hard chrome, a chromium carbide, a chromium nitride, a titanium carbide, a titanium carbonitride, a titanium nitride, a super steel, a ceramic (tungsten carbide, aluminum oxide, chromium oxide) or the like may be used. For plating, polishing by surface processing, grinding with #1000 drops of vermiculite, plane cutting with #1000 or more diamond vermiculite (cutting direction is perpendicular to the resin flow direction), electrolytic polishing, Processors such as electrolytic composite grinding. The preferred material of the lip of the casting mold 4 is the same as that of the casting mold 4. Further, the lip surface accuracy is preferably 0.5 S or less, and 0.2 S or less is preferable.

The crack of the casting mold 4 is configured to adjust the gap. This will be shown in Figure 3. One of the pair of lips forming the slit 32 of the casting mold 4 is a flexible lip 33 which is easily deformed with low rigidity, and the other is a fixed lip 34. However, most of the heating bolts 35 are in the casting mold 4 The width direction, that is, the longitudinal direction of the slit 32 is arranged at a certain pitch. Each of the heating bolts 35 is provided with a region 36 in which the electric heater 37 and the refrigerant passage are buried, and each of the heating bolts 35 runs through the respective regions 36 in a longitudinal direction. The base of the heating bolt 35 is fixed to the mold body 31, and the front end is connected to the outer surface of the flexible lip 33. While the area 36 is maintained under air cooling, the input force of the embedded electric heater 37 is adjusted to control the temperature of the region 36, whereby the heating bolt 35 is thermally expanded and contracted, and the position of the flexible lip 33 is changed to adjust the thickness of the film. A thickness gauge is provided at an important place after the molding, whereby the detected fluctuation thickness information is returned to the control device, and the thickness information is compared with the set thickness information by the control device, and the correction control amount from the same device is used. The signal controls the heating power or on rate of the heating bolt. The heating bolts are preferably 20 to 40 cm in length and 7 to 14 mm in diameter. In the case of plural, for example, dozens of heating bolts are preferably arranged at a pitch of 20 to 40 mm. Instead of the heating bolt, a gap adjusting member mainly composed of a bolt that adjusts the crack gap manually by moving forward and backward in the axial direction may be provided. The crack gap adjusted by the gap adjusting member is generally 200 to 1000 μm, preferably 300 to 800 μm, more preferably 400 to 600 μm.

The first to third cooling rolls are made of a seamless steel pipe having a wall thickness of about 20 to 30 mm, and the surface is processed into a mirror surface. The piping that flows into the cooling liquid is disposed inside so that it can be absorbed by the heat of the film on the roll by the coolant flowing into the pipe. Among the first to third cooling rolls, the first cooling roll 5 corresponds to the rotation support of the present invention.

On the other hand, the contact roller 6 coupled to the first cooling roller 5 has elasticity on the surface, and the pressing force against the first cooling roller 5 is along the first cooling roller. The surface of 5 is deformed and a clip is formed between the first cooling roller 5. That is, the contact roller 6 corresponds to the rolling rotor of the present invention.

Fig. 4 is a schematic cross-sectional view showing an embodiment of the touch roll 6 (hereinafter referred to as contact roll A). As shown in the figure, the contact roller A is a member in which the elastic roller 42 is disposed inside the flexible metal sleeve 41.

The metal sleeve 41 is made of stainless steel having a thickness of 0.3 mm and has flexibility. When the metal sleeve 41 is too thin, the strength is insufficient, and when it is too thick, the elasticity is insufficient. From this, it is understood that the thickness of the metal sleeve 41 is preferably 0.1 mm or more and 1.5 mm or less. The elastic roller 42 is provided with a rubber 44 as a roller on the surface of the metal inner cylinder 43 via a bearing. When the contact roller A is pressed in the direction of the first cooling roller 5, the elastic roller 42 pushes the metal sleeve 41 to the first cooling roller 5, and the metal sleeve 41 and the elastic roller 42 are shaped to match the first cooling roller 5. The deformation is performed to form a clip with the first cooling roll. The cooling water 45 flows into the space formed between the inside of the metal sleeve 41 and the elastic drum 42.

Fig. 5 and Fig. 6 show a contact roller B of another embodiment of the rolling rotor. The contact roller B has flexibility, and is formed of a seamless stainless steel pipe (thickness: 4 mm) outer cylinder 51 and a high-rigidity metal inner cylinder 52 that is disposed in the same axial shape inside the outer cylinder 51. The coolant 54 flows into the space 53 between the outer cylinder 51 and the inner cylinder 52. In detail, the contact roller B is provided with an outer cylinder support flanges 56a, 56b on the both end rotation shafts 55a, 55b, and a thin portion is attached between the outer circumferences of the two outer cylinder support flanges 56a, 56b. Wall metal outer cylinder 51. Further, the fluid is formed in the fluid discharge hole 58 of the fluid return passage 57 formed by the axial center portion of the one rotation shaft 55a, and the fluid The supply pipe 59 is disposed in the same axial shape, and the fluid supply pipe 59 is continuously fixed to the fluid cylinder 60 disposed in the axial center portion of the thin metal outer cylinder 51. Inner cylinder support flanges 61a, 61b are attached to both end portions of the fluid barrel 60, and the outer peripheral side outer cylinder support flanges 56b are disposed between the outer peripheral portions of the inner cylinder support flanges 61a, 61b by about 15 A metal inner cylinder 52 having a wall thickness of ~20 mm. Between the metal inner cylinder 52 and the thin-walled metal outer cylinder 51, a flow space 53 for forming a coolant of about 10 mm is formed, and a communication flow space 53 and a space are formed in the vicinity of both end portions of the metal inner cylinder 52. The cylinder supports the outflow port 52a and the inflow port 52b of the intermediate passages 62a, 62b on the outer sides of the flanges 61a, 61b.

Further, the outer cylinder 51 is made to have flexibility, flexibility, and restorability close to rubber elasticity, and is thinned in the range of the thin-walled cylinder theory to which elastic mechanics is applied. The flexibility evaluated by the thin-walled cylinder theory can be expressed by the wall thickness t/roller radius r, and the smaller the t/r, the higher the flexibility. When the contact roller B has a t/r ≦ 0.03, flexibility is an optimum condition. Generally, the contact roller used has a roll diameter R = 200 to 500 mm (roll radius r = R/2), a roll effective width L = 500 to 1600 mm, and r/L < 1 is a horizontally long shape. Therefore, as shown in FIG. 6, for example, when the roll diameter R=300 mm and the roll effective width L=1200 mm, the optimum range of the wall thickness t is 150×0.03=4.5 mm or less, and the average width of the molten sheet width to 1300 mm is When 98N/cm is pressed, compared with the rubber roller of the same shape, when the wall thickness of the outer cylinder 51 is 3 mm, the number of deflections is equal, and the width k of the outer cylinder 51 and the roller of the cooling roller is about 9 mm. The width of the rubber roller clip shows a similar value of about 12 mm, and can be pressed under the same conditions. And the deflection of the clip width k is about 0.05~0.1mm degree.

In particular, when t/r ≦ 0.03 is used, when the roll diameter R is 200 to 500 mm, particularly in the range of 2 mm ≦ t ≦ 5 mm, sufficient flexibility can be obtained, and thinning by machining. Walling is also easy to implement and is extremely practical. When the wall thickness is 2 mm or less, high-precision machining cannot be performed under elastic deformation during processing.

The converted value of 2 mm ≦t ≦ 5 mm is 0.008 ≦t/r ≦ 0.05 for a general roll diameter, and it is preferable to increase the wall thickness as compared with the roll diameter under the condition of t/r ≒ 0.03. For example, the roll diameter: R=200, t=2~3mm, roll diameter: R=500, t=4~5mm range to choose.

The contact rollers A and B are ejected to the first cooling roller by a spring means (not shown). The spring force of the spring means is F, and the value F/W (linear pressure) obtained by dividing the width W of the film in the clip along the rotational axis direction of the first cooling roll 5 is set to 9.8 to 147 N/cm. In the present embodiment, a clip is formed between the contact rollers A, B and the first cooling roller 5, and the clip can be corrected for flatness between the films. Therefore, the contact roller is formed of a rigid body, and the film is pressed for a long time by a small line pressure compared with the case where the clip is not formed between the first cooling rolls, so that the flatness can be more reliably corrected. That is, when the line pressure is less than 9.8 N/cm, the parting line cannot be sufficiently eliminated. Conversely, if the line pressure exceeds 147 N/cm, the film is hard to pass by the clip, and the thickness of the film may become uneven.

Further, when the surface of the contact roller A and B is made of metal, the surface of the contact rolls A and B can be made smoother than when the surface of the contact roll is made of rubber, so that a film having high smoothness can be obtained. And as the elastic roller 42 As the material of the elastic body 44, ethylene propylene rubber, neobutene rubber, silicone rubber or the like can be used.

Further, since the parting line can be satisfactorily released by the contact roller 6, the film viscosity at the time of the contact roll 6 pressing the film becomes important within an appropriate range. Further, it is known that the cellulose resin causes a relatively large change in viscosity depending on the temperature. Therefore, in order to set the viscosity when the contact roll 6 is pressed against the cellulose film to an appropriate range, it is necessary to set the film temperature when the contact roll 6 is pressed against the cellulose film to an appropriate range. Therefore, the inventors have found that when the glass transition temperature of the cellulose ester film is Tg, the film temperature T before the contact roll 6 is pressed is set to satisfy Tg < T < Tg + 110C. When the film temperature T is lower than Tg, the viscosity of the film is too high to correct the parting line. Conversely, when the temperature T of the film is higher than Tg + 110 ° C, the film surface and the roller cannot be uniformly followed, and the parting line cannot be corrected. It is preferably Tg + 10 ° C < T2 < Tg + 90 ° C, more preferably Tg + 20 ° C < T2 < Tg + 70 ° C. When the temperature of the film when the contact roll 6 is held by the cellulose film is set to an appropriate range, only the melt extruded from the casting die 4 is adjusted to the position P1 where the first cooling roll 5 is in contact with the first cooling roll 5 to contact the roll 6. The clip may be along the length L of the first cooling roller 5 in the rotational direction.

In the present invention, preferred materials for the first cooling roll 5 and the second cooling roll 6 include carbon steel, stainless steel, and resin. Further, the surface precision is preferably as high as possible, and the surface roughness is preferably 0.3 S or less, and preferably 0.01 S or less.

In the present invention, when the portion from the opening portion (mould lip) of the casting mold 4 to the first cooling roll 5 is depressurized to 70 kPa or less, the effect of correcting the parting line is found to be greater. The pressure reduction is preferably 50 to 70 kPa. Self-casting The method of maintaining the pressure of the opening of the die 4 (the lip) to the portion of the first cooling roll 5 at 70 kPa or less is not particularly limited, and a method of covering the periphery of the roll with a pressure-resistant member by a pressure-resistant member, and the like, and the like, may be mentioned. . In this case, it is preferable that the suction device is to prevent the device body from becoming a place where the sublimate is attached, and it is preferable to perform treatment such as heating by a heater. In the present invention, if the suction pressure is too small, the sublimate cannot be effectively sucked, so it is necessary to set an appropriate suction pressure.

In the present invention, the film-shaped cellulose ester-based resin in a molten state is transported from the T-die 4 in the order of the first cooling roll 5, the second cooling roll 7, and the third cooling roll 8 It is solidified by cooling to obtain an unextended cellulose ester film 10.

In the embodiment of the present invention shown in Fig. 1, the cooled and solidified unstretched film 10 which has been peeled off from the third cooling roll 8 by the peeling roll 9 is introduced into the stretching machine 12 after passing through the dancer roll (film tension adjusting roll) 11, Here, the film 10 is extended in the lateral direction (width direction). This extension allows the molecules in the film to be oriented.

A known tenter or the like can be used as a method of extending the film in the width direction. In particular, when the extending direction is the wide direction, lamination with the polarizing film can be carried out in the form of a roll, which is preferable. The retardation axis of the cellulose ester film formed of the cellulose ester resin film is broad in the width direction.

On the other hand, the transmission axis of the polarizing film is generally also in the width direction. When the polarizing plate in which the transmission axis of the polarizing film and the slow phase axis of the optical film are laminated in parallel is assembled in the liquid crystal display device, the display contrast of the liquid crystal display device can be improved and a good viewing angle can be obtained.

The glass transition temperature Tg of the film constituent material is formed by making the film The material type and the ratio of the constituent materials can be controlled under different conditions. When a retardation film as an optical film is produced, the Tg is preferably 120 ° C or higher, preferably 135 ° C or higher. In the liquid crystal display device, the temperature of the device itself changes due to the temperature rise of the device itself, for example, the temperature rise from the light source changes the temperature environment of the film. When the Tg of the film is lower than the ambient temperature of the film at this time, the retention value as the orientation state from the molecule fixed to the inside of the film and the size of the film are greatly changed by stretching. When the Tg of the film is too high, the temperature at which the film constituent material is formed into a film is too high, so that the energy consumption of heating is increased, and the decomposition of the material itself at the time of film formation also causes coloration, and therefore, Tg is 250. Below °C is preferred.

Further, in the extending step, a known heat setting condition, cooling, and relaxation treatment are performed, and the optical film is appropriately adjusted to have desired characteristics.

When the physical properties of the phase film and the viewing angle of the liquid crystal display device are increased, the extension step and the heat setting treatment can be appropriately selected in order to impart a function as a phase film. In the case where the stretching step and the heat setting treatment are carried out, the heating and pressurizing step of the present invention can be carried out before the stretching step and the heat setting treatment.

When a phase difference film as a cellulose ester film is produced, and the function of the composite polarizer protective film is further combined, it is necessary to perform refractive index control, which can be performed by an extending operation and an extending operation as an optimum method. The extension method will be described below.

In the step of extending the retardation film, the retention of Ro and Rt can be controlled in accordance with the increase of 1.0 to 2.0 times in one side of the cellulose resin and the increase in the in-plane of the film by 1.01 to 2.5 times. its In the middle, Ro represents in-plane retention, and Rt represents retention in the thickness direction.

The retention values Ro and Rt are obtained by the following formula.

Formula (i)Ro=(nx-ny)×d Formula (ii) Rt=((nx+ny)/2-nz)×d

(wherein nx represents the refractive index in the axial direction of the film plane, ny represents the refractive index in the direction of the in-phase axis of the film, and nz represents the refractive index in the thickness direction of the film (refractive index is 23 ° C, 55% RH) In the environment, the value measured at a wavelength of 590 nm), d represents the film thickness (nm)).

The refractive index of the optical film was measured using an Abbe refractometer (4T), the film thickness was a commercial micrometer, and the retention value was measured using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.).

The stretching is performed, for example, in the longitudinal direction of the film and in a direction orthogonal to the film surface, that is, in the width direction, sequentially or simultaneously. At this time, when the stretching ratio in at least one direction is too small, a sufficient phase difference cannot be obtained, and when it is too large, it is difficult to extend, and film breakage occurs.

For example, when extending in the direction of the melt casting, when the shrinkage in the width direction is excessively large, the value of nz is excessively large. At this time, the web shrinkage of the film is suppressed or extended in the width direction to be improved. When extending in the width direction, a refractive index distribution is generated in the width direction. This distribution occurs when the tenter method is used, because the film is extended in the width direction, and a contraction force is generated in the central portion of the film, and the end portion is a phenomenon which occurs when it is fixed, which is a so-called bending phenomenon. At this time, it also extends in the casting direction, and the bowing phenomenon can be suppressed, and the phase difference distribution in the width direction can be reduced.

By extending in two axial directions parallel to each other, the resulting film can be reduced The film thickness changes. When the film thickness of the retardation film is excessively changed, the phase difference is uneven, and when used in a liquid crystal display, unevenness in coloring or the like occurs.

The film thickness variation of the cellulose ester film is ±3%, and preferably in the range of ±1%. For the above purpose, the method of extending in the two-axis direction orthogonal to each other is effective, and the stretching ratio in the two-axis direction orthogonal to each other is 1.0 to 2.0 times in the last casting direction and 1.01 to 2.5 times in the width direction. The range is preferably such that it is preferably 1.01 to 1.5 times in the casting direction and is preferably in the range of 1.05 to 2.0 times in the width direction.

When there is an absorption axis of a polarizer in the longitudinal direction, it is aligned with the transmission axis of the polarizer in the width direction. When a long-length polarizing plate is to be obtained, it is preferable that the retardation film extends in the width direction to obtain the 遅 phase axis.

When a cellulose ester obtained by positive birefringence is used for stress, when the above structure is extended in the width direction, the retardation axis of the retardation film can be obtained in the width direction. At this time, in order to improve the display quality, the retardation axis of the retardation film is preferably in the width direction, and the retention value of the object is desired.

The condition of the formula (stretching ratio in the width direction) > (stretching ratio in the casting direction) must be satisfied.

After the extension, the end portion of the film is cut into a slit by the cutter 13, and then the embossing processing device formed by the embossing ring 14 and the back roller 15 is subjected to emboss processing at both ends of the film. After the winding up by the winding device 16, it is possible to prevent the bonding or scratching of the cellulose ester film (original winding) F. The embossing process is such that the pattern of the convex and concave is processed by heating or pressurizing the metal ring having the side surface. And film The grip portion of the clip at both ends is generally deformed and cannot be used as a film product, so it is reused as a raw material after being cut.

Next, the winding step of the film is such that the outer peripheral surface of the film wound into a cylindrical shape and the shortest distance from the outer peripheral surface of the conventional moving conveyance roller are kept constant, and the film is taken up by the winding roller. Further, before the winding of the drum, means for removing or reducing the surface potential of the film is provided.

The coiler related to the manufacture of the optical film of the present invention can be used by a general user, and can be wound by a winding method such as a constant tension method, a fixed torque method, a taper tension method, or a program tension control method with a constant internal stress. take. Further, the initial winding tension at the time of winding the polarizing plate protective film is preferably 90.2 to 300.8 N/m.

In the film winding step of the method of the present invention, the film is preferably taken up under the environmental conditions of a temperature of 20 to 30 ° C and a humidity of 20 to 60% RH. Thus, in the case where the temperature and humidity of the film winding step are regulated, the humidity change resistance in the thickness direction retention (Rt) can be improved.

When the temperature of the winding step is less than 20 ° C, wrinkles are generated, and the film roll quality is deteriorated, and the practicality is not good. When the temperature in the winding step of the film exceeds 30 ° C, wrinkles still occur, and the film roll quality is deteriorated, and the practicality is not good.

Further, if the humidity of the film winding step is less than 20% RH, it is easy to be charged, and the film roll quality is deteriorated, and the practicality is not good. When the humidity of the film winding step exceeds 60% RH, problems such as roll quality, bonding failure, and deterioration in conveyability may be poor.

When the cellulose ester film is taken up into a roll shape, it is only a circle as a core. The core of the cylinder may be any material, preferably a hollow plastic core, and is not limited to a heat-resistant plastic material which is resistant to the heat treatment temperature, and may be phenol. Resin, xylene resin, melamine resin, polyester resin, epoxy resin and other resins. Further, it is preferable to use a thermosetting resin which is reinforced by a filler such as glass enamel. For example, a hollow plastic core is used: an outer diameter of 6 inches (hereinafter referred to as 2.54 cm) made of FRP, and a core of 5 inches in inner diameter.

The number of rolls of these cores is preferably 100 or more, more preferably 500 or more, and the thickness is preferably 5 cm or more, and the width of the film substrate is preferably 80 cm or more, and more preferably 1 m or more.

The film thickness of the cellulose ester film of the present invention varies depending on the purpose of use, and is preferably 10 to 500 μm as the processed film. In particular, the lower limit is 20 μm or more, preferably 35 μm or more. The upper limit is 150 μm or less, preferably 120 μm or less. The especially good range is 25~90 μm. When the retardation film has a polarizing plate protective film, when the film is too thick, the polarizing plate after the polarizing plate is processed is too thick, and is used in a liquid crystal display of a notebook computer or a portable electronic device, and is particularly incapable of being suitable for thin and lightweight. The purpose. On the other hand, when the film is too thin, it is difficult to express as a retardation film, and the moisture permeability of the film becomes high, and the ability to protect the polarizer from humidity is not preferable.

The retardation axis or the phase inversion of the retardation film exists in the film surface, and the angle formed by the film formation direction is θ 1, θ 1 is -1 to +1 ∘, preferably -0.5 to +0.5 ∘.

θ 1 is an orientation angle, and θ 1 is measured by using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.).

When θ 1 satisfies the above relationships, the display image can be made to have high luminance, light leakage can be suppressed or prevented, and a faithful color can be reproduced for the color liquid crystal display device.

When the retardation film is subjected to the VA form of the multi-regionalization, the phase difference film is disposed such that the phase difference axis of the retardation film is θ1, and when the region is disposed in the above region, the display image quality can be improved, and the polarizing plate and the liquid crystal display device can be used. In the case of the MVA form, for example, the configuration shown in Fig. 7 can be employed.

In Fig. 7, 21a and 21b are protective films, 22a and 22b are retardation films, 25a and 25b are polarizers, 23a and 23b are the retardation axes of the film, and 24a and 24b are the transmission axis directions of the polarizers, 26a. 26b is a polarizing plate, 27 is a liquid crystal cell, and 29 is a liquid crystal display device.

The retention Ro distribution of the cellulose ester film in the in-plane direction is preferably 5% or less, preferably 2% or less, and particularly preferably 1.5% or less. Further, the distribution of the retained Rt in the thickness direction of the film is preferably 10% or less, more preferably 2% or less, and particularly preferably 1.5% or less.

In the retardation film, the variation in the distribution of the retention value is preferably small. When a polarizing plate containing a retardation film in a liquid crystal display device is used, when the variation in the retention distribution is small, it is preferable from the viewpoint of preventing color unevenness.

Adjusting the retardation film to have a retention value suitable for improving the quality of the liquid crystal cell of the VA form or the TN form, and particularly for dividing the VA form into the above multiple regions and applying the MVA form, adjusting the in-plane retention ratio of Ro 30 nm is 95 nm or less, and the thickness direction retention Rt is adjusted to be larger than 70 nm and 400 nm or less.

The above-mentioned in-plane retention Ro is arranged in two polarizing plates in crossed Nicols ( Crossed Nicol), the liquid crystal cells are arranged between the polarizing plates. For example, when the configuration is as shown in FIG. 7 , when viewed from the normal direction of the display surface, when viewed in the crossed Nicols state, when viewed from the slope of the normal line of the display surface, the polarizing plate is crossed. The Cole state produces a deviation, which compensates for the light leakage caused by this. The thickness direction is retained in the TN form or the VA form described above, and particularly in the case where the liquid crystal cell in the MVA form is in the black display state, the birefringence of the liquid crystal cell seen by the slope can be similarly compensated.

As shown in FIG. 7, in the liquid crystal display device, when two polarizing plates are arranged on the upper and lower sides of the liquid crystal cell, 22a and 22b in the drawing are arranged to select the thickness direction retention Rt, which satisfies the above range, and the thickness direction stays Rt. The total value of both is greater than 140 nm, and preferably 500 nm or less. At this time, when both of the faces 22a and 22b are retained by Ro and the thickness direction is retained by Rt, the productivity of the industrial polarizing plate can be improved. It is particularly preferable that the in-plane retention Ro is greater than 35 nm and is 65 nm or less, and the thickness direction retention Rt is greater than 90 nm and is 180 nm or less, and is suitable for the MVA liquid crystal cell having the constitution shown in FIG.

In the liquid crystal display device, for example, a polarizing plate protective film for sale, for example, a TAC film having a thickness of 35 to 85 μm and a thickness of 35 to 85 μm at a thickness of Rt=20 to 50 nm is retained in the surface, for example, for use in a drawing. When the position of 22b is 7, the polarizing film of the other polarizing plate can be disposed. For example, the retardation film disposed in 22a of FIG. 7 can be used in which the in-plane retention Ro is larger than 30 nm and is 95 nm or less, and the thickness direction is The retention Rt is larger than 140 nm and is 400 nm or less. This improves the display quality and is also good from the production side of the film.

Recycling In the film forming step, the pressed portion of the pressed film at both ends of the cut film is subjected to pulverization treatment or, if necessary, granulation treatment, and then it is preferably used as a raw material for a film of the same type or a raw material for a film of a different type.

Functional Layer When the optical film of the present invention is produced, the transparent conductive layer, the cured film layer, the antireflection layer, the slippery layer, the easy adhesion layer, the antiglare layer, the barrier layer, the optical compensation layer, and the like can be applied before and/or after the extension. Sex layer. In particular, it is preferable to provide at least one layer selected from the group consisting of a transparent conductive layer, a cured film layer, an antireflection layer, an easy-adhesion layer, an anti-glare layer, and an optical compensation layer. At this time, various surface treatments such as corona discharge treatment, plasma treatment, and chemical liquid treatment may be applied as necessary.

Polarizer When the cellulose ester film of the present invention is used as a polarizing plate protective film, the method for producing the polarizing plate is not particularly limited, and it can be produced by a general method. The inner side of the cellulose ester film of the present invention is alkalized, and the treated cellulose ester film is immersed in at least one side of the polarizing film formed by stretching in the iodine solution, and is pasted with a fully alkalized polyvinyl alcohol aqueous solution. It is better. The cellulose ester film of the present invention is also used on the other side, or another polarizing plate may be used to protect the film. For the cellulose ester film of the present invention, a commercially available cellulose ester film can be used as the polarizing plate protective film for the other side. For example, as a cellulose ester film sold, KC8UX2M, KC4UX can be cited. , KC5UX, KC4UY, KC8UY, KC12UR, KC8UCR-3, KC8UCR-4, KC4FR-1, KC8UY-HA, KC8UX-RHA (above is Konicaminolta). Alternatively, it is preferable to use a polarizing plate protective film which is an optical compensation film of an optical heterogeneous layer formed by orienting a liquid crystal compound such as a discotic liquid crystal, a rod-like liquid crystal or a cholesteric liquid crystal. For example, an optical anisotropic layer can be formed by the method described in JP-A-2003-98348. By using the cellulose ester film of the present invention, a polarizing plate having excellent planarity and a stable viewing angle expansion effect can be obtained. A film such as a cyclic olefin resin other than a cellulose ester film, an acrylic resin, a polyester, or a polycarbonate may be used as the polarizing plate protective film on the other side.

In place of the above-described alkali treatment, it is possible to carry out a polarizing plate processing which is easy to process as described in JP-A-6-94915 and JP-A-6-118232. The polarizing film which is a component mainly composed of a polarizing plate is a light-transmitting element which passes only a polarizing surface in a certain direction, and a representative polarizing film which is now known is a polyvinyl alcohol-based polarizing film, and this is a polyvinyl alcohol. The film is obtained by dyeing iodine with those obtained by dyeing with a dichroic dye. The polarizing film is preferably formed by subjecting a polyvinyl alcohol aqueous solution to film formation, stretching it after one-axis stretching, or dyeing it, and then performing one-axis stretching, preferably after treatment with a boron compound. The film thickness of the polarizing film is 5 to 40 μm, preferably 5 to 30 μm, and particularly preferably 5 to 20 μm. A polarizing plate is formed on the surface of the polarizing film by laminating the surface of the cellulose ester film of the present invention. It is preferably bonded by a water-based adhesive containing a fully alkalized polyvinyl alcohol or the like as a main component.

Since the polarizing film extends in the direction of one axis (usually in the long direction), the polarizing plate is extended in a high-temperature and high-humidity environment (usually in the long direction). It will tighten and will extend in a direction perpendicular to the extension (usually in the width direction). When the film thickness of the polarizing plate protective film is thinner, the expansion ratio of the polarizing plate is larger, and in particular, the amount of shrinkage in the extending direction of the polarizing film is large. In general, since the extending direction of the polarizing film is bonded to the casting direction (MD direction) of the polarizing plate protective film, it is particularly important to suppress the expansion ratio of the casting direction when the polarizing plate protective film is formed into a film. The cellulose ester film of the present invention has excellent dimensional stability and can be suitably used as such a polarizing plate protective film.

That is, the durability test under conditions of 60 ° C and 90% RH does not increase the wavy spots, and even if it is a polarizing plate having an optical compensation film on the back side, it provides good discrimination without changing the viewing angle characteristics after the durability test. Sex.

The polarizing plate is composed of a polarizing film and a protective film for protecting both sides thereof, and a protective film is laminated on the opposite side of the polarizing plate on the opposite side. The protective film and the release film are used for the purpose of protecting the polarizing plate during inspection of the product when the polarizing plate is shipped. At this time, the protective film is bonded for the purpose of protecting the surface of the polarizing plate, and is used to bond the polarizing plate to the reverse surface of the surface of the liquid crystal panel. Further, the release film is used for the purpose of covering the adhesive layer of the liquid crystal panel, and is used for bonding the polarizing plate to the surface of the liquid crystal cell.

"Liquid Crystal Display Device" When a polarizing plate containing a polarizing plate protective film (also including a phase difference film) containing the optical film of the present invention is used, it can exhibit higher display quality than a general polarizing plate, and is particularly preferably a multi-region type liquid crystal display device. Multi-region type liquid crystal display device by means of birefringence .

The polarizing plate of the present invention can be used in the form of MVA (Multi-domein Vertical Alignment), PVA (Patterned Vertical Alignment), CPA (Continuous Pinwheel Alignment), OCB (Optical Compensated Bend), IPS (In Plane Switching), and the like. It is not limited to the configuration of a specific liquid crystal form or a polarizing plate.

The liquid crystal display device can be applied as a device for colorization and animation display, and the present invention can improve display quality, improve contrast improvement or resistance of a polarizing plate, and can exhibit real moving image display without fatigue.

In a liquid crystal display device including a polarizing plate containing a retardation film, a polarizing plate containing the retardation film of the present invention is disposed one on the liquid crystal cell or two on both sides of the liquid crystal cell. At this time, when the phase difference film side of the present invention contained in the polarizing plate is used to face the liquid crystal cell of the liquid crystal display device, the display quality can be improved. In Fig. 7, the films of 22a and 22b are liquid crystal cells facing the liquid crystal display device.

In such a configuration, the retardation film of the present invention can compensate for optical properties in the liquid crystal cell. When the polarizing plate of the present invention is used in a liquid crystal display device, at least one polarizing plate in the polarizing plate of the liquid crystal display device may be used as the polarizing plate of the present invention. By using the polarizing plate of the present invention, the display quality can be improved, and the liquid crystal display device having excellent viewing angle characteristics can be improved.

In the polarizing plate of the present invention, a polarizing plate protective film of a cellulose derivative is used as the opposite side of the retardation film, and a general-purpose TAC film or the like can be used. Polarized plate protection at a distance from the liquid crystal cell The film can be configured with other functional layers in order to improve the quality of the display device.

For example, in order to improve anti-reflection, anti-glare, scratch resistance, adhesion prevention, and brightness enhancement, a known functional layer as a display may be used as a film contained in a constituent or may be bonded to the surface of the polarizing plate of the present invention, but is not limited thereto. herein.

In the general retardation film, when the variation of Ro or Rt is small as the retention value, it is desirable to obtain stable optical characteristics. In particular, in a birefringent type liquid crystal display device, these variations may cause unevenness in image formation.

According to the long-distance retardation film produced by the melt casting film forming method of the present invention, the cellulose resin is mainly used. Therefore, the alkali treatment of the cellulose resin is utilized, and the alkali treatment step can be utilized. When the resin constituting the polarizer is polyvinyl alcohol, the fully alkalized polyvinyl alcohol aqueous solution can be bonded to the retardation film of the present invention in the same manner as the conventional polarizing plate protective film. Therefore, the present invention is excellent in application to the polarizing plate processing method in the past, and is particularly excellent in that a long-sized roller polarizing plate can be obtained.

The manufacturing effect obtained by the present invention is particularly remarkable in the case of a long-length roll of 100 m or more, and the manufacturing effect of the polarizing plate production can be obtained when the length is 1500 m, 2500 m, or 5000 m.

For example, in the production of the retardation film, the length of the roll is 10 to 5000 m, preferably 50 to 4,500 m in consideration of productivity and transportability, and the film width at this time may be selected from the width of the polarizer or the width of the manufacturing process. The film is produced at a width of 0.5 to 4.0 m, preferably 0.6 to 3.0 m, and can be supplied to a polarizing plate after being wound into a roll shape, and a film of a multiple width or more is produced and wound up. After the roll, the desired width of the roll is obtained after cutting, and the roll can be used for the processing of the polarizing plate.

When the polarizing plate protective film is manufactured, a functional layer such as an antistatic layer, a cured film layer, a slippery layer, an adhesive layer, an antiglare layer, and a barrier layer may be applied before and/or after stretching. At this time, various surface treatments such as corona discharge treatment, plasma treatment, and chemical liquid treatment can be carried out as necessary.

The composition of the cellulose resin containing the additives such as the plasticizer, the ultraviolet absorber, and the matting agent may be subjected to co-extrusion, or may be an optical film having a laminated structure. For example, an optical film such as a skin layer/core layer/skin layer can be produced. For example, the matting agent can be placed in a large amount in the skin layer or only in the skin layer. The amount of the plasticizer and the ultraviolet absorber to be placed may be larger than that of the skin layer, or may be placed only in the core layer. Further, the core layer and the skin layer may be changed in type of a plasticizer or an ultraviolet absorber. For example, a low-volatility plasticizer and/or an ultraviolet absorber may be contained in the skin layer, and a plasticizer excellent in plasticity or ultraviolet absorption may be added to the core layer. Excellent UV absorber. The glass transition temperature of the skin layer and the core layer may be different, and the glass transition temperature of the core layer is preferably lower than the glass transition temperature of the skin layer. At this time, the glass transition temperature of both the skin and the core was measured, and the average value calculated by the volume fraction was defined as the above-mentioned glass transition temperature Tg. Moreover, the viscosity of the melt containing the melt-flowing cellulose ester may be different between the skin layer and the core layer, and the viscosity of the skin layer > the viscosity of the core layer, or the viscosity of the core layer, and the viscosity of the skin layer may also be .

The dimensional stability of the cellulose ester film of the present invention is 80 ° C 90% RH when the film size after 24 hours at 23 ° C 55% RH is used as a reference. The dimensional change value is less than ±2.0%, preferably less than 1.0%, and more preferably less than 0.5%.

When the cellulose ester film of the present invention is used as a protective film for a polarizing plate of a retardation film, when the retardation film itself has a variation of the above range or more, the absolute value and the orientation angle of the retention property of the polarizing plate are different from those of the original setting. When entering or exiting, it causes a decrease in display quality improvement or deterioration in display quality.

[Examples]

The present invention will be specifically described below by way of examples, but the invention is not limited thereto.

<Synthesis of Cellulose Ester>

(Synthesis of cellulose ester 1) 80 g of acetic acid and 30 g of propionic acid were added to 30 g of cellulose (dissolved pulp made of Nippon Paper Co., Ltd.), and the mixture was stirred at 54 ° C for 30 minutes. After cooling the mixture, 7 g of cooled acetic anhydride, 120 g of propionic anhydride, and 1.2 g of sulfuric acid were added to the ice bath to carry out esterification. In the esterification, the mixture was stirred for 150 minutes while being adjusted so as not to exceed 40 °C. After the completion of the reaction, a mixture of 30 g of acetic acid and 10 g of water was dropped over 20 minutes to hydrolyze the excess anhydride. While maintaining the temperature of the reaction liquid at 40 ° C, 90 g of acetic acid and 30 g of water were added and stirred for 1 hour. Dissolve the mixture in an aqueous solution containing 2 g of magnesium acetate and stir for a while, then filter, and wash thoroughly with water until the pH of the washing solution After being neutral, it was dried to obtain cellulose ester 1. With respect to the obtained cellulose ester 1, the degree of substitution (X) of the ethyl thiol group and the degree of substitution (Y) of the propyl thiol group were determined by the method specified in ASTM D817-96, and X = 1.31, Y. = 1.23. Further, under the above conditions, a number average molecular weight of 66,000 was determined by gel permeation chromatography, and a 1% mass reduction temperature Td (1.0) was measured in air using a differential thermogravimetric analyzer to obtain 292 °C.

(Synthesis of cellulose ester 2~15) The synthesis operation of the cellulose ester 1 was carried out in the same manner as in the synthesis of the cellulose ester 1, except that the amounts of acetic acid, acetic anhydride, propionic acid, and propionic anhydride were changed, to obtain cellulose esters 2 to 15.

For each cellulose ester 1 to 15, the degree of substitution (X) of the ethyl thiol group, the degree of substitution (Y) of the fluorenyl group, the value of X + Y, the value of X-Y, the number average molecular weight (Mn), and 1% by mass The values of the reduced temperature Td (1.0) are shown in Table 1.

(Comparison of cellulose esters 16~25) The cellulose esters 16 to 23 were compared and synthesized in the same manner as the cellulose ester 1 except that the cellulose acetate 1 was synthesized and the amount of acetic acid, acetic anhydride, propionic acid, and propionic anhydride was changed. On the one hand, the cellulose esters 24 and 25 were compared for the synthesis of cellulose ester 1, and a combination of acetic acid, acetic anhydride, butyric acid, and butyric anhydride was used, and the same synthesis operation as that of cellulose ester 1 was carried out except that these amounts were changed. synthesis.

For the obtained comparative cellulose esters 16~25, the substitution of ethyl hydrazide Degree (X), degree of substitution of thiol (Y), value of X+Y, value of X-Y or degree of substitution of butyl sulfhydryl (Z), value of X+Z, value of X-Z, and number average molecular weight (Mn) The value of the 1% mass reduction temperature Td (1.0) is shown in Table 1.

Example 1

[Production of Sample 1-1 having an optical film made of cellulose ester (hereinafter simply referred to as cellulose ester film)] The cellulose ester film 1-1 of the present invention was produced by melt casting using the above-mentioned synthesized cellulose ester and various additives as described below.

The cellulose ester 1 was dried under reduced pressure at 130 ° C for 4 hours, and after cooling to room temperature, the additive was mixed. The above mixture was melt-mixed and pelletized at 230 ° C using a 2-axis extruder. Further, the glass had a glass transition temperature Tg of 140 °C.

The pellet was melted at 250 ° C in a nitrogen atmosphere, and extruded by a casting die 4 on the first cooling roll 5, and a film was sandwiched between the first cooling roll 5 and the contact roll 6 to be formed. In addition, 0.02 parts by mass of cerium oxide particles, AEROSILNAX50 (manufactured by AEROSIL Co., Ltd., Japan), and 0.02 parts by mass of KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) were added to the hopper opening of the intermediate portion of the extruder 1 . .

The heating bolt was adjusted so that the gap width of the casting mold 4 was 0.5 mm within 30 mm from the width direction end of the film, and the other position was 1 mm. As the contact roller, a contact roller A in which water of 80 ° C of cooling water flows is used.

The position P1 from the resin which is extruded from the casting die 4 to the first cooling roller 5 to the position P2 of the upper end of the first cooling roller 5 in the direction of rotation of the first cooling roller 5 and the contact roller 6 is along the first position The circumferential length L of the cooling drum 5 was set to 20 mm. Thereafter, the contact roller 6 is separated from the first cooling roller 5, and the temperature T of the molten portion before the nip of the first cooling roller 5 and the contact roller 6 is nip is measured. In the present embodiment, the temperature T of the melting portion before the nip of the first cooling roller 5 and the contact roller 6 is passed through a thermometer (the HA manufactured by Anritsu Co., Ltd.) at a position higher than the upstream end P2 of the clip by 1 mm. -200E) Determination. In the measurement results of this example, the temperature T was 141 °C. The line pressure of the first cooling roll 5 of the touch roll 6 was 14.7 N/cm. Further, the film was introduced into a tenter and stretched 1.3 times in the width direction at 160 ° C, and then cooled to 30 ° C while being 3% relaxed in the width direction. Thereafter, the plate was opened, and the plate holding portion was cut at both ends of the film. The knurling processing was performed with a width of 10 mm and a height of 5 μm, and the winding tension was 220 N/m, and the taper degree was 40%. The extrusion amount and the extraction speed were adjusted so that the film had a thickness of 80 μm, and the completed film width became a winding thickness of 1430 mm. The dimensions of the core are 152 mm in inner diameter, 165 to 180 mm in outer diameter, and 1550 mm in length. As the main material of the core, a pre-stained resin in which an epoxy resin is impregnated into glass fibers or carbon fibers is used. The surface of the core is coated with an epoxy-based conductive resin, and the surface is ground to process the surface roughness to Ra. 0.3 μm. And the roll length is 2500m. The original film roll sample of the present invention was used as the cellulose ester film roll 1-1. Further, a part of the cellulose ester film was cut out from the original film roll sample, and this was designated as the cellulose ester film 1-1 of the present invention.

[Production of cellulose ester film 1-2~1-25] In the production of the cellulose ester raw film roll 1-1, the type of the cellulose ester was changed to the same as in Table 1, and the cellulose ester original film roll 1-2 to 1-15 of the present invention was produced in the same manner, and compared. Cellulose ester original film roll 1-16~1-25. Further, the amount of the cellulose ester substituted for the cellulose ester 1 to be used is the same as that of the cellulose ester 1. Further, a part of the cellulose ester film is cut out from the cellulose ester original film roll 1-2 to 1-15 of the present invention and the comparative cellulose ester original film roll 1-16 to 1-25 in the same manner as described above. Each of the cellulose ester films 1-2 to 1-15 of the present invention and the comparative cellulose ester film 1-16 to 1-25.

The structures of the plasticizer-A, IRGANOX 1010, GSY-P101, Sumilizer GS, and TINUVIN 928 used in Example 1 are shown below. Further, the cellulose esters 1 to 23 are cellulose acetate propionates, and the cellulose esters 24 and 25 are cellulose acetate butyrate.

The obtained cellulose ester raw film roll sample and the cellulose ester film sample were evaluated by the following methods. The results are shown in Table 2.

"horseback failure, core transfer" The coiled cellulose ester raw film roll sample is double-packed with the polyethylidene sheet, and is stored at 25 ° C, 50% RH as shown in (a), (b), and (c) of FIG. 8 . Save for 30 days under conditions. Thereafter, taken by the box The polyethylated sheet is opened and reflected on the fluorescent tube of the original film roll surface to observe the curvature or slight disorder, and the horseback failure is classified according to the following level.

◎: Seeing the fluorescent lamp in a straight line △: I saw some fluorescent lamps appear curved ×: I saw a spotlight on the fluorescent light.

Moreover, the original film roll sample after being taken up and stored is subjected to a dot-shaped deformation of 50 μm or more, or a band-shaped deformation in the width direction, and the core transfer is clearly observed, and the measurement is performed from the core portion to a few m, and below The level is graded.

◎: The core part is less than 15m ○: The core part of the core is less than 15~30m △: The core part is less than 30~50m ×: The core part is 50m or more

"The volume begins to die" When the winding of the original anti-film is carried out on the winding core, when the winding starts to collapse, the original reverse film is taken out from the winding core, and the winding operation is performed again. Calculate the number of defects at this time. This operation was averaged 10 times and graded at the following level.

◎: 0 times or more and less than 1 time ○: 1 or more times less than 3 times △: not more than 3 times 5 times ×: 5 or more times

Flatness Each cellulose ester film sample was cut into a size of 90 cm in width and 100 cm in length, and fixed on a sample table of five 50 W fluorescent lamps at a height of 1.5 m at an angle of 45 Å, and each film sample was placed on the sample table. The unevenness which was observed after being reflected on the surface of the film was visually observed and determined as follows. This method can determine "continuous" and "dead".

◎: 5 fluorescent lamps are in a straight line ○: A little fluorescent light is curved △: The whole fluorescent lamp shows a little bending ×: Fluorescent lamp shows a big bend

Evaluation of Volume A 5 mm × 5 cm cellulose ester film sample was cut out, placed in a constant temperature and humidity chamber at a temperature of 28 ° C and 55% RH for 24 hours, placed on a flat plate, and a curvature radius was used to obtain a radius of curvature having the same curvature as the sample. The size and ease of handling of the rolls are evaluated as described below.

Curvature radius: 1/Round radius (1/m) with the same curvature as the sample ◎: Not up to 0~5 ○: Not up to 5~10 △: not up to 10~30 ×: 30 or more

Among them, ◎ and ○ indicate that it is easy to handle and practical, and Δ below indicates that the treatment is extremely difficult.

"Changing Coefficient of Change (CV)" The retention property was measured at intervals of 1 cm in the width direction of the cellulose ester film, and the coefficient of variation (CV) of the retention property obtained by the following formula was shown. Determined to use the automatic complex refractometer KOURA. 21ADH (manufactured by Oji Scientific Co., Ltd.), in the environment of 28 ° C, 55% RH, at a wavelength of 590 nm, the 3-dimensional complex refractive index measurement is performed every 1 cm interval in the width direction of the sample, and the measured value is substituted into the following formula. Seek from the child.

In-plane retention Ro=(nx-ny)×d Retention in the thickness direction Rt = ((nx + ny) / 2 - nz) × d

Wherein d represents the thickness (nm) of the film, the refractive index nx (the in-plane maximum refractive index of the film, also referred to as the refractive index in the direction of the slow axis), and ny (refraction in the film in-plane and the retarded axis at right angles) Rate), nz (refractive index of the film in the thickness direction). The standard deviation of the (n-1) method was obtained for each of the obtained in-plane and thickness-direction retention. The retention distribution is obtained by using the coefficient of variation (CV) shown below. In the actual measurement, n is set to 130 to 140.

Coefficient of variation (CV) = standard deviation / retention average ◎: deviation (CV) is less than 1.5% ○: The deviation (CV) is 1.5% or more, less than 5% △: The deviation (CV) is 5% or more, less than 10% ×: The deviation (CV) is 10% or more

Alkalinization Adaptability Immersing a 120 μm thick polyvinyl alcohol film in a mass containing iodine 1 An aqueous solution of 2 parts by mass of potassium iodide and 4 parts by mass of boric acid was extended 4 times at 50 ° C to prepare a polarizer. The cellulose ester film sample was subjected to alkali treatment for 60 seconds under a 2.5 N-aqueous sodium hydroxide solution at 40 ° C, dried by water washing, and alkalized on the surface. On both surfaces of the above-mentioned polarizer, the alkali-treated surface of the cellulose ester film was bonded to both surfaces using a 5% aqueous solution of a fully alkalized polyvinyl alcohol as an adhesive to prepare a polarizing plate for evaluation which was followed by a protective film.

Next, the evaluation polarizing plate was treated at 80 ° C and 90% RH for 1200 hours, and the bonding state of the polarizer and the protective film was observed, and the grade was given based on the following.

◎: not stripped ○: Only a slight peeling, which is a practically problem-free level △: more or less peeling occurs, which is a practical problematic level ×: peeling occurred

Among them, ○ or more is a level which is judged to be practically problem-free in the suitability of alkalizing treatment.

Polarizer durability test (whitening) Two pieces of a 500 mm × 500 mm polarizing plate sample prepared in the above-described alkalization treatment evaluation were subjected to heat treatment (condition: 120 ° C for 120 hours), and any one of the longitudinal or transverse center line portions in the straight state was measured. The length of the large edge whitening portion was calculated for the ratio of the side length (500 mm), and the ratio was determined as follows. The edge portion of the polarizing plate that does not pass light in a state of being straight out with the edge being whitened becomes a state of passing light, so Determined by visual inspection. In the state of the polarizing plate, the failure of the edge portion display is not seen.

◎: edge whitening is less than 5% ○: edge whitening is 5% or more, less than 10% △: edge whitening is 10% or more, less than 20% ×: edge whitening is 20% or more

Among them, ○ above is judged to be practically no problem.

As described above, as a result of Table 2, the cellulose ester raw film roll samples 1-1 to 1-15 of the present invention are even for the comparative example cellulose ester raw film roll sample 1-16 to 1-25. The cellulose ester film which is difficult to produce due to deformation failure of the original film roll, such as a horseback failure, a small core transfer, and a roll start, is preserved over a long period of time. In addition, it is known that the cellulose ester film of the present invention is a fiber having a high degree of flatness and alkalization treatment, and a small variation in rollability and retention property, for the cellulose ester film itself cut out from the original roll. Aliester film. Further, the polarizing plate produced by using the cellulose ester film of the present invention is an optical film excellent in durability and practically excellent.

Example 2

The cellulose of the present invention was produced in the same manner as the cellulose ester raw film roll 1-1 of Example 1 except that the combination of the cellulose ester, the plasticizer, the deterioration preventing agent, and the ultraviolet resistant agent described in Table 3 was changed. The ester film roll 2-1 to 2-18, and the comparative cellulose ester film roll 2-19, 2-20, and the cellulose ester film 1-1 of Example 1 were used to produce the present invention. Cellulose ester film 2-1 to 2-18, and comparative cellulose ester film 2-19, 2-20. Further, polarizing plates 2-1 to 2-18 of the present invention and comparative polarizing plates 2-19 and 2-20 were produced in the same manner as in the polarizing plate 1-1 of Example 1. Further, the numerical values in parentheses in the column of the plasticizer, the deterioration preventing agent, and the ultraviolet resistant agent in Table 3 indicate the parts by mass of each material used for 100 parts by mass of the cellulose ester.

Moreover, the plasticizer-B, the plasticizer-C, the plasticizer-D, the plasticizer-E, the plasticizer-F, the plasticizer-G, the Sumilizer GP (the plasticizer-D used in Example 2) The structure of the company, which is manufactured by Sumitomo Chemical Co., Ltd., TINUVIN 900 (manufactured by Ciba Specialty Chemicals Co., Ltd.), Sumisorb 250 (manufactured by Sumitomo Chemical Co., Ltd.), and LA31 (manufactured by Adeka Co., Ltd.) is as follows.

The same evaluation as in Example 1 was carried out on the produced cellulose ester raw film roll, cellulose ester film, and polarizing plate. The results are shown in Table 4.

As described above, the results of Table 4 show that the cellulose ester raw film roll samples 2-1 to 2-18 of the present invention are the cellulose ester raw film roll samples 2-19 and 2-20 of the comparative example, which are Even if the horseback is damaged for a long period of time and the core transfer is small, the roll starts to collapse and the cellulose film which is difficult to produce due to deformation failure of the original film roll. Further, it is known that the cellulose ester film of the present invention is a cellulose ester film which is cut out from the original roll, and the cellulose ester film of the present invention has high flatness and alkalization treatment, and has little variation in rollability and retention property. Ester film. Further, the polarizing plate produced by using the cellulose ester film of the present invention is an optical film excellent in durability and practically excellent. In the original film roll 2-1, the film sample 2-1, and the polarizing plate sample 2-1, the exemplified compound (2)-8 was substituted with the same amount of the exemplified compound (2)-3, and the same evaluation was performed. In the same manner, the same good results as in each sample No. 2-1 in Table 4 were obtained. Even when the compound (2)-8 exemplified in the same manner as above was substituted with the same amount of the exemplified compound (2)-45, the same good results as in the sample No. 2-1 were obtained. On the other hand, in the original film roll sample 2-5, the film sample 2-5, and the polarizing plate sample 2-5, GSY-P101 was the same mass part of bismuth (2,4-di-t-butyl-benzene). When the same evaluation was carried out, the same results as in the sample No. 2-5 of Table 4 were obtained except that the results of the whitening evaluation were ◎ to ○. . Further, in the original film roll sample 2-7, the film sample 2-7, and the polarizing plate sample 2-7, IRGANOX 1010 was used in the same mass portion of 1,1,1-trishydroxymethylethane-shen-[3- Substituting (3,5-di-t-butyl-4-hydroxyphenyl)propionate], the same evaluation was carried out, and good results similar to those of each sample No. 2-7 in Table 4 were obtained.

Example 3

The cellulose ester raw film of the present invention was produced in the same manner as in Example 1 except that the cellulose ester and various additives were used, and the thickness of the film was changed to 40 μm, and the amount of extrusion, the suction speed, and the stretching ratio were adjusted. Volume 3-1 is a cellulose ester film which is difficult to produce even if the horseback is damaged for a long period of time and the core transfer is small, and the original film roll such as the roll starts to collapse. When the cellulose ester film was cut out from the original roll and evaluated, it was found to be a cellulose ester film having high flatness and alkalization treatment, and having little variation in rollability and retention, and the use of the cellulose. The polarizing plate produced by the ester film is an optical film excellent in durability and practically excellent.

Example 4

(As a characteristic evaluation of a liquid crystal display device) The polarizing plate of the 32-type TV AQ-32AD5 manufactured by Sharp Corporation of the VA type liquid crystal display device was peeled off, and each of the polarizing plates produced in Examples 1 to 3 (the cellulose ester film of the present invention produced in Example 3) was used. 3-1, The polarizing plate 3-1 was produced in the same manner as the polarizing plate 1-1. ) Cut to fit the size of the LCD cell. The liquid crystal cell was clamped, and the two polarizing plates prepared as described above were directly crossed and bonded to each other under the condition that the polarizing axis of the polarizing plate was unchanged from the original one, thereby producing a 32-type VA type color liquid crystal display, and a cellulose ester film. After evaluating the characteristics of the polarizing plate, it is known that the liquid crystal display device using the polarizing plates 1-1 to 1-15, 2-1 to 2-18, and 3-1 of the present invention is used for the comparative polarizing plate 1-16~1- 25, 2-19, 2-20 liquid crystal display devices, the contrast is high, and shows excellent display without color unevenness. In this way, it is confirmed that it can be used as a polarizing plate for an image display device such as an excellent liquid crystal display.

1‧‧‧Extrusion machine

2‧‧‧Filter

3‧‧‧Static mixer

4‧‧‧cast molding

5‧‧‧Rotating support (1st cooling roller)

6‧‧‧挟Rotating body (contact roller)

7‧‧‧Rotating support (2nd cooling roller)

8‧‧‧Rotating support (3rd cooling roller)

9, 11, 13, 14, 15‧‧‧Transport roller

10‧‧‧ Cellulose Telluride Film

12‧‧‧Extension machine

16‧‧‧Winding device

21a, 21b‧‧‧ Protective film

22a, 22b‧‧‧ phase difference film

23a, 23b‧‧‧ The direction of the slow axis of the film

24a, 24b‧‧‧ the direction of the transmission axis of the polarizer

25a, 25b‧‧‧ polarizer

26a, 26b‧‧‧ polarizing plate

27‧‧‧ liquid crystal cell

29‧‧‧Liquid crystal display device

31‧‧‧ mould body

32‧‧‧Slit

41‧‧‧Metal casing

42‧‧‧Flexible roller

43‧‧‧Metal inner tube

44‧‧‧ rubber

45‧‧‧Cooling water

51‧‧‧Outer tube

52‧‧‧Inner tube

53‧‧‧ Space

54‧‧‧ Coolant

55a, 55b‧‧‧ rotating shaft

56a, 56b‧‧‧ outer cylinder support flange (flange)

60‧‧‧ Fluid shaft tube

61a, 61b‧‧‧ inner cylinder support flange (flange)

62a, 62b‧‧‧ intermediate access

110‧‧‧core body

117‧‧‧Support board

118‧‧‧Rack

120‧‧‧Cellulose ester film roll

Fig. 1 is a flow chart showing an embodiment of an apparatus for producing a cellulose ester film of the present invention.

Fig. 2 is a flow chart showing an enlarged portion of an important part of the manufacturing apparatus of Fig. 1.

[Fig. 3] Fig. 3(a) shows an external view of an important part of a casting mold, and Fig. 3(b) shows a cross-sectional view of an important part of a casting mold.

Fig. 4 is a cross-sectional view showing a first embodiment of the rolling rotor.

Fig. 5 is a cross-sectional view showing the rotation axis of the second embodiment of the rolling rotor in a vertical plane.

Fig. 6 is a cross-sectional view showing a plane of a rotating shaft of a second embodiment including a rolling rotor.

Fig. 7 is an exploded perspective view showing a schematic configuration of a liquid crystal display device.

Fig. 8 is a view showing a state of storage of a cellulose ester original film roll.

Claims (13)

An optical film which is a film forming material which heats and melts a film forming material containing at least one type of a plasticizer and a cellulose ester, and is formed by a melt casting method, and is characterized by using a substituent type of the cellulose ester. A cellulose ester which satisfies the conditions of the following formulas (1) to (4) at the same degree of substitution is used for film formation; Formula (1) 1.25≦X≦1.43 Formula (2) 1.15≦Y≦1.33 Formula (3) 2.40 ≦X+Y<2.75 Formula (4)-0.05≦XY<0.20 (wherein X represents the degree of substitution by an ethyl group, and Y represents the degree of substitution by a propyl group). The optical film of claim 1, wherein the cellulose ester has a 1% mass reduction temperature Td (1.0) at 270 ° C or higher. The optical film of claim 1 or 2, wherein the film forming material further contains at least one phenolic compound. The optical film of claim 1 or 2, wherein the film forming material further contains at least one phosphorus compound. The optical film of claim 1 or 2, wherein the film forming material further contains at least one alkyl radical scavenger. The optical film of claim 1 or 2, wherein the film forming material further comprises at least one phenolic compound species, at least one phosphorus compound, and at least one alkyl radical capture Agent. An optical film according to claim 3, wherein the phenolic system The compound is a hindered phenol compound. The optical film of claim 4, wherein the phosphorus compound is a phosphite compound. The optical film of claim 5, wherein the alkyl radical scavenger is a compound represented by the following general formula (1) or a compound represented by the following general formula (2); Wherein R ₁ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ₂ and R ₃ each independently represent an alkyl group having 1 to 8 carbon atoms; Wherein R ₁₂ to R ₁₅ each independently represent a hydrogen atom or a substituent, R ₁₆ represents a hydrogen atom or a substituent, and n represents an integer of 1 to 4; when n is 1, R ₁₁ represents a substituent, and n is 2 When an integer of ~4, R ₁₁ represents a 2 to 4 valent linking group]. The optical film of claim 1 or 2, wherein the plasticizer is a polyol ester. The optical film of claim 1 or 2, wherein the film forming material further contains a benzotriazole compound. A polarizing plate characterized in that the optical film of any one of the first to eleventh aspects of the invention is at least one side of the polarizer. A liquid crystal display device characterized in that a polarizing plate according to claim 12 of the patent application is used for at least one side of a liquid crystal cell.