WO2006117948A1 - Cellulose ester film, process for producing the same, polarizing plate using said cellulose ester film, and liquid crystal display device - Google Patents

Abstract

This invention provides a process for producing a cellulose ester film, which can efficiently develop a phase difference value, is small in a variation in the phase difference value, has excellent stability, and has no significant haze, and a polarizing plate and a liquid crystal display device using the same. In the production process, a cellulose ester film containing fine particles, which are acicular and have birefringence, is produced by a solution casting method, and the production process is characterized by comprising previously preparing a fine particle dispersion liquid containing at least the fine particles and a resin for dispersing the fine particles, then mixing the fine particle dispersion liquid, a solvent, and a cellulose ester together to prepare a dope, and solution casting the dope.

Description

 Specification

 Cellulose ester film, production method thereof, polarizing plate using cellulose ester film, liquid crystal display device

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a method for producing a cellulose ester film containing fine particles having a high acicular ratio such as acicular crystals used for optical applications at a high concentration, a polarizing plate using the same, and a liquid crystal display device. .

 Background art

 [0002] Various liquid crystal display methods such as IPS, VA, and OCB have been proposed, and the need for a phase difference film is increasing. As means for imparting a phase difference to the film, a method of stretching a polycarbonate, a cycloolefin film, or a cellulose acetate resin film has been proposed. When polycarbonate film is used, it is necessary to attach a retardation plate to the polarizing plate. In the case of cellulose acetate film, the protective film and retardation film of the polarizing plate can also be used. The manufacturing process can be simplified and the cost can be reduced. However, in the case of cellulose acetate-based resin, the range of phase difference values that can be expressed is limited, and it has been difficult to cope with various liquid crystal display methods.

 Meanwhile, as a method for controlling birefringence, methods using birefringent fine particles described in Patent Documents 1 and 2 have been proposed. We have studied to stably expand the phase difference control range of cellulose ester film using this method. However, it is difficult to control the retardation value of the cellulose ester film to which these fine particles are added, and the fluctuation is large.

 Patent Document 1: Pamphlet of International Publication No. 01Z0253643

 Patent Document 2: JP 2004-109355 A

 Disclosure of the invention

 Problems to be solved by the invention

[0004] The present invention has been made in view of the above problems, and an object thereof is to efficiently calculate a phase difference value. To provide a method for producing a cellulose ester film, a polarizing plate using the same, and a liquid crystal display device. It is.

 Means for solving the problem

 [0005] The above-described problems of the present invention are achieved by the following configurations.

 [0006] 1. A method for producing a cellulose ester film containing needle-like fine particles having birefringence by a solution casting method, wherein a fine particle dispersion containing at least the fine particles and a resin for dispersing the fine particles is obtained. A method for producing a cellulose ester film, comprising preparing the dope beforehand, mixing the fine particle dispersion, a solvent, and cellulose ester to prepare a dope, and casting the dope in a solution.

 [0007] 2. The method for producing a cellulose ester film as described in 1 above, wherein a media disperser having a bead diameter of 0.03 to 0.3 mm is used when preparing the fine particle dispersion.

 [0008] 3. The method for producing a cellulose ester film as described in 1 or 2 above, wherein the fine particle dispersion contains a cellulose ester.

 [0009] 4. In a method for producing a cellulose ester film, a dope containing fine particles having a needle shape and birefringence, a cellulose ester and a solvent is cast on a support, and then dried in any of the drying steps. And the step of measuring the birefringence of the stretched film, and the result obtained in the step of measuring the birefringence determines the content of the fine particles contained in the dope. A method for producing a cellulose ester film, comprising adjusting.

 [0010] 5. A cellulose ester film produced by the method for producing a cellulose ester film described in any one of 1 to 4 above.

[0011] 6. A polarizing plate comprising the cellulose ester film as described in 5 above on at least one surface.

 [0012] 7. A liquid crystal display device comprising the polarizing plate described in 6 above.

 More specifically, the above-described problem of the present invention can be solved by the following configuration.

(1) Fine particles containing needle-like fine particles having birefringence, a solvent, and a fine particle-dispersing resin A method for producing a cellulose ester film, comprising: preparing a polymer dispersion, mixing the fine particle dispersion, a solvent, and a cellulose ester to produce a dope, and casting the dope in a solution.

 [0015] (2) The method for producing a cellulose ester film according to (1), wherein a media disperser having a bead diameter of 0.03 to 0.3 mm is used when preparing the fine particle dispersion. .

 [0016] (3) The fine particle dispersion was prepared by preparing a fine particle solution of a fine particle having a needle shape and birefringence and a solvent, and adding a dispersion resin for fine particles, followed by redispersion. The method for producing a cellulose ester film according to (1), which is a fine particle dispersion.

 [0017] (4) The fine particle-dispersed resin contained in a dispersion of acicular and birefringent fine particles has a weight average molecular weight of 3,000-200,000 (1) or The method for producing a cellulose ester film as described in (3).

 [0018] (5) A homopolymer or copolymer in which a fine particle-dispersing resin contained in a dispersion of acicular and birefringent fine particles has an ethylenically unsaturated monomer unit, acrylic acid or Methacrylic acid ester homopolymer or copolymer, methacrylic acid methyl ester homopolymer or copolymer, cellulose ester, cellulose ether polyurethane resin, polycarbonate resin, polyester resin, epoxy resin, and ketone resin The method for producing a cell mouth ester film according to any one of (1) to (4), wherein at least one kind is used.

 [0019] (6) The solvent contained in the dispersion of needle-like fine particles having birefringence contains at least one solvent selected from methylene chloride, methyl acetate, ethanol, methanol, and acetone power. The method for producing a cellulose ester film according to any one of (1) to (5).

[0020] (7) In a method for producing a cellulose ester film, a dope containing fine particles having a needle shape and birefringence, a cellulose ester, and a solvent is cast on a support, and then dried. A step of stretching in any of the drying steps, a step of measuring the birefringence of the stretched film, and the results obtained in the step of measuring the birefringence are included in the dope. Adjusting the content of fine particles with needle shape and birefringence A method for producing a cellulose ester film.

 [0021] (8) A method of adjusting the content of acicular and birefringent fine particles contained in the dope is obtained by adding an additive solution of acicular and birefringent fine particles in-line. The method for producing a cellulose ester film according to (7), wherein the content is adjusted.

 [0022] (9) The total degree of acyl group substitution of the cellulose ester is 2.4 to 2.8. Method.

[0023] (10) Any one of (1) to (9) above, wherein the concentration of cellulose ester in the dope prepared by dissolving cellulose ester in a solvent is 15 to 30% by mass 1 The manufacturing method of the cellulose-ester film of description.

[0024] (11) The cellulose ester as described in any one of (1) to (10) above, wherein the concentration of the dispersing resin in the fine particle dispersion is 0.1 to 10% by mass. Film production method

[0025] (12) a cellulose ester according to any force one of the fine particle content of the cellulose ester film is characterized in that 1. from 5 to 30 weight _^0/0 (1) to (11) Film Manufacturing method.

 [0026] (13) A cellulose ester film produced by the method for producing a cellulose ester film according to any one of (1) to (12) above.

[0027] (14) Manufactured by the method for producing a cellulose ester film according to any one of (1) to (12) above, and Ro = 105 to 350 nm, Nz = 0.2 to 0.7 Senore mouth senenoreinoremu characterized by.

 [0028] (15) A polarizing plate having the cellulose ester film according to (13) or (14) on at least one surface.

[0029] (16) A liquid crystal display device comprising the polarizing plate according to (15) on at least one surface of a liquid crystal cell.

(17) A liquid crystal display device comprising the polarizing plate according to (15) on at least one surface of a liquid crystal cell of a horizontal electric field switching mode type liquid crystal display device (for example, IPS method, FFS method). . The invention's effect

 [0031] According to the present invention, a method for producing a cellulose ester film capable of efficiently expressing a retardation value, excellent in stability with little variation in the retardation value, and having less haze, and the use thereof A polarizing plate and a liquid crystal display device can be provided. Brief Description of Drawings

 FIG. 1 is a diagram for explaining a stretching angle in a stretching step.

 FIG. 2 is a schematic view showing an example of a tenter process used in the present invention.

 FIG. 3 is a schematic diagram showing the configuration of a transverse electric field switching mode type liquid crystal display device that is preferable to the present invention.

 FIG. 4 is a schematic diagram showing the direction of the absorption axis Z and the transmission axis of a cellulose ester film, a polarizer, and a liquid crystal cell of a lateral electric field switching mode type liquid crystal display device that is preferable to the present invention.

 FIG. 5 is a schematic view showing a configuration of a lateral electric field switching mode type liquid crystal display device of the present invention and a comparative example.

 FIG. 6 is a diagram schematically showing a dope preparation step, a casting step, and a drying step of the solution casting film forming method according to the present invention.

 FIG. 7 is a diagram schematically showing an apparatus for measuring absolute filtration accuracy.

 Explanation of symbols

[0033] 1, 10 Melting pot

 3, 6, 12, 15 Filter

 4, 13 Stock tank

 5, 14 Liquid feed pump

 8, 16 conduit

 20 Junction pipe

 21 Mixer

 30 dice

 31 Metal support

 32 Web

33 Peeling position 34 Tenter device

 35 roll dryer

 A Filter media sample

 B Liquid to be filtered

 C filtrate

 M manometer

 P Low pressure vacuum pump

 S Stirrer

 V valve

 60 Polarizer

 62 Cell mouth ester film B (polarizing plate protective film)

 64 polarizer

 66 Cellulose ester film A (polarizing plate protective film) according to the present invention

 68 Polarizing plate protective film

 70 Horizontal electric field switching mode type liquid crystal cell

 71 LCD rubbing axis

 72, 74 Polarizer transmission axis

 73, 75 Polarizer absorption axis

 76 Slow axis of cellulose ester film A according to the present invention

BEST MODE FOR CARRYING OUT THE INVENTION

As a result of intensive studies, the inventor of the present invention is a method for producing a cellulose ester film containing needle-like and birefringent fine particles by a solution casting method, and at least the needle-like and birefringent fine particles and the fine particles A method for producing a cellulose ester film, comprising preparing a fine particle dispersion containing a dispersion of glycerin in advance and then mixing the fine particle dispersion with a dope prepared by dissolving a cellulose ester in a solvent. Thus, it has been found that a method for producing a cellulose ester film can be obtained in which a retardation value can be efficiently expressed, and the dispersion of the retardation value is small, the retardation stability is excellent, and the haze is small. [0035] Further, in the method for producing a cellulose ester film, a dope containing needle-like birefringent fine particles, cellulose ester, and a solvent is cast on a support, and then dried in a method of producing a cellulose ester film. A step of stretching in any one of them, a step of measuring the birefringence of the stretched film, and a result obtained in the step of measuring the birefringence, It has been found that the method for producing a cellulose ester film to be adjusted provides a method for producing a cellulose ester film having excellent retardation stability and low haze.

 [0036] The fine particles having a needle shape and birefringence function effectively by being oriented in a certain direction in the film, and can obtain a cellulose ester film having a conventional phase difference characteristic, which will be described later. I can do it. As means for orienting in a certain direction, there are an orientation in a step of casting on a support and an orientation in a stretching step of stretching in any of the drying steps. The present invention promotes acicular and birefringent fine particles to be more uniformly oriented in a certain direction in both of the above-mentioned orientations. This effect achieves the object of the present invention.

[0037] On the other hand, as a method for adding matting agent fine particles to a cellulose ester film, Japanese Patent Application Laid-Open No. 2001-2799 [Claim 3] states that “a dispersion in which fine particles are dispersed in a solvent in advance is mixed with a solvent and cellulose ester. A cellulose ester characterized in that the fine particle additive solution obtained by mixing with a mixed solution of the above is mixed with a dope prepared by dissolving cellulose ester in a solvent, cast onto a support, and then dried. The effect is that the number of agglomerates of 30 m or more existing on the film lm ² is reduced and the haze value can be kept low. There is no suggestion that “a phase difference can be efficiently expressed” which is an effect obtained when fine particles having birefringence are used.

[0038] In addition, it is considered that the method of the present invention makes it difficult to produce a mass of fine particles having acicular and birefringence in the dope, so that it is considered that the retardation stability is excellent and the haze is reduced. Fine particles having birefringence may form lumps of various sizes in the dope, and large ones need to be filtered and removed. In this case, the amount of fine particles having a needle shape and birefringence contained in the dope is reduced, so that it is presumed that a desired phase difference value force is shifted. Filtration filter in which the amount of particulate change is not always constant It is thought to change due to clogging of the filter or fluctuations in the filtration pressure. It was thought that the desired phase difference value could not be obtained if there were many small lumps. As a result of intensive studies to solve this problem, a cellulose ester film is produced by casting a dope containing fine particles having a needle shape and birefringence, a cellulose ester and a solvent on a support, and then drying the substrate. The method includes a step of stretching in any of the drying steps, a step of measuring the birefringence of the stretched film, and the results obtained in the step of measuring the birefringence are included in the dope By adjusting the content of the fine particles, a cellulose ester film having a more stable retardation value can be provided.

 [0039] According to the method of the present invention, the added fine particles are easily oriented as much as lump and the like are less likely to occur in the dope, and the retardation value can be efficiently expressed. For this reason, the amount of needle-shaped and birefringent fine particles added can be reduced, and productivity can be improved.

 [0040] Further, the added fine particles can be made to express more phase difference by being oriented. Examples of the orientation method include a method in which the film is stretched to TD or MD at the time of film production, or a method in which a flow of dope is formed at the time of casting and the particles are oriented along this flow. Furthermore, it is possible to promote particle orientation with an electric field or magnetic field.

 [0041] Hereinafter, the present invention will be described in detail.

[Material for forming fine particle dispersion]

 (Acicular fine particles with birefringence)

 The needle-shaped fine particles having birefringence (hereinafter also referred to as birefringent fine particles) used in the present invention are not particularly limited as long as they are needle-shaped and have birefringence.

[0043] As the birefringent fine particles, birefringent fine particles described in WO01Z0253643 or JP-A-2004-109355 can be used. For example, various carbonates such as calcium carbonate, strontium carbonate, magnesium carbonate, manganese carbonate, cobalt carbonate, zinc carbonate, barium carbonate, etc., various oxides typified by titanium oxide, MgSO-5Mg (OH) · 3

 4 2

Birefringent whisker such as Η 0, 6CaO-6SiO · Η 0, 9A1 Ο · 2Β For example, tetragonal, hexagonal and rhombohedral crystals are preferably uniaxial birefringent crystals, orthorhombic, monoclinic and triclinic crystals. These may be single crystals or polycrystals.

 [0045] Also, polystyrene or acrylic resin rod-like or short fiber-like particles are preferably used. For example, it may be a short fiber particle having polystyrene resin or acrylic resin and manufactured by finely cutting ultrafine fibers. These fibers are preferably stretched during the manufacturing process because they easily develop birefringence. In addition, it is preferable that the rosin contained in these particles is crosslinked! /.

 [0046] However, various things can be used as long as the above-mentioned requirements such as size and needle ratio are satisfied.

 [0047] These birefringent fine particles preferably have a major axis (absolute maximum length) of 10 to 500 nm and an acicular ratio of 2 or more, and particularly preferably an acicular ratio of 2 to LOO. It is preferably 3-30. For the acicular ratio, the absolute maximum length and the diagonal width force of the fine particles are also obtained by the following equation. This can also determine the image data force obtained by electron microscopic observation of fine particles or fine particles contained in the film.

 [0048] Needle ratio = absolute maximum length Z diagonal width

 Diagonal width is the shortest distance between two straight lines when the image of a particle projected with two straight lines parallel to the absolute maximum length is sandwiched between them.

 [0049] It is preferable that the birefringent fine particles are surface-treated with a silane coupling agent, a titanate coupling agent, or the like! /.

 [0050] The birefringence of the birefringent fine particles is defined as follows. The refractive index for light polarized in the major axis direction of the birefringent fine particle is npr, and the average refractive index for light polarized in the direction perpendicular to the major axis direction is nvt. The birefringence Δη of the birefringent fine particle is defined by the following equation.

 [0051] A n = npr-nvt

 That is, if the refractive index in the major axis direction of the birefringent fine particles is larger than the average refractive index in the direction orthogonal thereto, positive birefringence is obtained, and if it is vice versa, negative birefringence is obtained.

[0052] The absolute value of the birefringence of the birefringent fine particles used in the present invention is not particularly limited. A force of 0.01-0.3 is preferred, and 0.05-0.3 is more preferred.

[0053] Birefringent crystals having positive birefringence include MgSO · 5Mg (OH) · 3H 0, 6C

 4 2 2 aO-6SiO · Η 0, 9A1 O · 2Β O, TiO (rutile crystal). Negative birefringence

 2 2 2 3 2 3 2

 Examples of the birefringent crystal exhibiting properties include calcium carbonate and strontium carbonate.

 [0054] In the case of acicular crystals, it means a material whose refractive index in the long direction of the crystal is smaller than the refractive index in the direction perpendicular thereto.

 <Carbonate fine particles>

 The carbonate fine particles can be produced by a uniform precipitation method or a carbon dioxide compounding method.

 For example, it can be produced by the methods described in JP-A-3-88714, JP-B-55-51852, JP-A-59-223225, and the like.

 [0057] The strontium carbonate crystal can be obtained by bringing strontium ions dissolved in water into contact with carbonate ions. Carbonate ions can be obtained by adding carbon dioxide gas to a solution containing a strontium compound by a method such as publishing carbon dioxide, or by adding a substance that generates carbonate ions to react or decompose. For example, strontium carbonate crystal fine particles can be produced by a method described in JP-A-2004-35347, and strontium carbonate fine particles obtained by this method can be preferably used as birefringent fine particles. Examples of the substance that generates carbon dioxide include urea, and strontium carbonate fine particles can be obtained by reacting carbon dioxide ions and strontium ions generated together with urea hydrolase. In order to obtain fine crystals, it is preferable to lower the temperature as much as possible. Cooling below the freezing point is preferable because fine crystal particles can be obtained. For example, it is also preferable to add an organic solvent such as ethylene glycol as a freezing point depressing substance. It is preferable to add so that the freezing point is below 5 ° C below freezing point. This makes it possible to obtain fine particles of strontium carbonate having an average particle size in the major axis direction of 500 nm or less.

[0058] Strontium carbonate is a biaxial birefringent crystal. According to Japanese Patent Laid-Open No. 2004-35347, the refractive index in each optical axis direction is n (na, nb, nc) = (l. 520, 1.666, 1.669 It has been reported that the long axis direction of the acicular crystal is almost the same as the optical axis direction of refractive index 1.520. Therefore, it has a negative birefringence effect with respect to the orientation direction of the acicular crystal. Since the strontium carbonate crystal particles are in a needle-like (rod-like) form, they can be statistically oriented in a predetermined direction by applying a stress in a state of being dispersed in a viscous medium.

 [0059] A specific method for producing strontium carbonate crystals is shown below.

 [0060] Synthesis Example 1

Against water 375g [This, urea 81. 75 g (water [this against 21.8 mass _^0/0) were added ϊ¾ strontium 30. 75 g (2 wt% 8. in water). Further reaction (20 mass _^0/0 in water) 75. OOG ethylene glycol as organic solvent to the reaction solution to perform below the freezing point was added. This solution was put into a reaction vessel, stirred and cooled while being irradiated with ultrasonic waves.

[0061] Shinto Kagaku Co., Ltd., three-one motor BLh600 as an agitation motor, Honda Electronics Co., Ltd. as a water bath with ultrasonic irradiation function, ultrasonic cleaner W-113MK II, manufactured by Thomas Scientific Instruments Co., Ltd. as a cooler A closed tank type handy cooler TRL-C13 was used.

 [0062] By circulating an ethylene glycol antifreeze (Thomas Scientific Instruments Co., Ltd., Nybrine (registered trademark)) in a water bath with a cooler, the temperature of the reaction solution is lowered to -5 ° C, and -5 ° Kept at C. Subsequently, 1.50 g of digestive enzyme Urease was added to the reaction solution. After the digestive enzyme was added, crystals started to precipitate in the reaction solution and became cloudy. The reaction was continued for 12 hours while maintaining the temperature of the reaction solution at 5 ° C.

 [0063] Thereafter, the temperature of the reaction solution was raised to 20 ° C, and the crystals were aged for 12 hours while maintaining the temperature at 20 ° C. The obtained crystal was taken out by filtration and dried. From the scanning electron microscope (SEM) photograph of the dried crystals, strontium carbonate needle crystal particles having a length of 500 nm or less (approximately 400 nm on average) are obtained.

 [0064] Synthesis Example 2

In water 300 g, methanol 60 g (20 mass _^0/0 in water) to prepare a suspension of example Tooka卩(26.7 wt% in water) strontium hydroxide octahydrate 80 g. This suspension is put into a reaction vessel, and energy is given to the reaction system while preventing aggregation of the generated particles as much as possible. In order to promote the formation of crystal nuclei, the suspension was stirred with a stirring motor (manufactured by Shinto Kagaku Co., Ltd., Three-One Motor BLh600). Furthermore, ultrasonic waves were irradiated by a water bath with an ultrasonic irradiation function (manufactured by Honda Electronics Co., Ltd., ultrasonic cleaner W-113MK-Π). In order to keep the temperature of the suspension at 10 ° C, an ethylene glycol antifreeze (Thomas Science Co., Ltd.) sold in a water bath using a cooler (Tomas Scientific Instruments Co., Ltd., closed tank type handy cooler TRL—C13). Equipment manufactured by Nybrine (registered trademark) was circulated.

 [0065] CO gas and N gas gas mixer (Koflock Co., Ltd., MiNi—Gascom PMG—1

 twenty two

 ) And mix in a volume ratio of CO: N = 30: 70 and in suspension 200mlZmin

 twenty two

 Introduced at a flow rate of. The mixed gas was introduced into this suspension until the pH was stable at around 7, and then the mixed gas introduction was stopped.

 [0066] A silane coupling solution was prepared separately from this suspension. Acetic acid was added to 40 g of water to a pH of about 5.3, and a silane coupling agent (3-dalicydoxypropyltrimethoxysilane) was further added and stirred for about 3 hours.

 [0067] The amount of the silane coupling agent was 30% by mass with respect to strontium carbonate. The prepared silane coupling solution was added to the suspension, and surface treatment was performed while stirring with a stirring motor for 24 hours. In order to remove unreacted components, the suspension can be suction filtered through a 0.1 μm pore size filter paper, and the product can be washed by stirring in 500 ml of acetone for 24 hours and filtered again. The product was dried in a vacuum dryer. The obtained crystals were observed with an electron microscope to obtain strontium carbonate crystals having an average length of 200 nm or less.

 [0068] In the present invention, acicular and birefringent fine particles are dispersed in a fine particle dispersion together with an organic solvent and a fine particle dispersing resin described below. By using the needle-shaped and finely divided fine particle dispersion prepared in this way, a cellulose ester film having a stable retardation can be obtained and can be used as an optical compensation film. .

 [0069] (Acid for dispersing fine particles having needle shape and birefringence)

It is preferable that the weight average molecular weight of 3,000 to 200,000 is used for dispersing fine particles of acicular and birefringent particles. More preferably, the weight average molecular weight is 3,000 to 90,000. Good Good.

 [0070] Needle-like fine particles for dispersing fine birefringence are homopolymers or copolymers having ethylenically unsaturated monomer units, acrylic acid or methacrylic acid ester homopolymers or copolymers, It is preferably at least one selected from methacrylic acid methyl ester homopolymer or copolymer, cellulose ester, cellulose ether polyurethane resin, polycarbonate resin, polyester resin, epoxy resin and ketone resin.ヽ. When cellulose ester is used as a dispersing resin, the total degree of acyl substitution is 2.0 to 2.8.

 [0071] Even if these coffins are contained in a dope (cellulose concentration 15 to 30% by mass) which is a high-concentration cellulose ester solution used for solution casting, a uniform haze increase is small. It is a resin capable of forming a film.

 [0072] In the fine particle dispersion containing fine particles having a needle shape and birefringence, the concentration of the resin for the dispersion is preferably 0.1 to 10% by mass. Further, the concentration of fine particles in this dispersion is preferably 0.2 to 10% by mass.

 [0073] In the present invention, it is preferable to control the viscosity of the fine particle dispersion in the range of 10 to 500 mPa's.

 [0074] Therefore, as a result of studying various types of fats and oils by changing the type and molecular weight of the fats, the present inventors prefer the followings for the fats, and also the weight average molecular weight. In the case of 3,000-90,000, the dispersion state of the fine particle dispersion can be remarkably improved by using a wide range of coagulants. It has been found that it is possible to form a dope that is more soluble and less prone to lumping. The weight average molecular weight is more preferably 5,000-50,000, and further preferably 10,000-30,000. There is no particular limitation on the resin, and conventionally known resins can be widely used, but the following resins can be used more suitably.

[0075] Examples of the resin preferably used in the fine particle dispersion according to the present invention include a homopolymer or copolymer having an ethylenically unsaturated monomer unit, and more preferably. , Polymethyl acrylate, polyethyl acrylate, polypropyl acrylate, polycyclohexyl acrylate, alkyl acrylate copolymer, polymethyl methacrylate, polymer A homopolymer or copolymer of acrylic acid or methacrylic acid ester such as ethyl acrylate, polycyclohexyl methacrylic acid, alkyl methacrylate ester copolymer, and acrylic acid or methacrylic acid ester is transparent, A homopolymer or copolymer having excellent compatibility and having an acrylate or methacrylate unit, particularly a homopolymer or copolymer having an acrylic acid or methyl methacrylate unit is preferred. Specifically, polymethyl methacrylate is preferable. An alicyclic alkyl ester of acrylic acid or methacrylic acid such as polyacrylic acid or polymethacrylic acid cyclohexane is preferred because it has advantages such as high heat resistance, low hygroscopicity and low birefringence.

 [0076] Other examples of the resin include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate and the like having a acyl group substitution degree of 1.8 to 2.80; Alkyl group substitution degree 2.0 to 2.80 cellulose ether resin, such as methylenoatenore, senorelose ethinoreatenore, cellulose propyl ether; polyamide resin of polymer of alkylene dicarboxylic acid and diamine; Polymer of alkylene dicarboxylic acid and diol, Polymer of alkylene diol and dicarboxylic acid, Polymer of cyclohexane dicarboxylic acid and diol, Polymer of cyclohexane diol and dicarboxylic acid, Aromatic dicarboxylic acid and Polyester resin such as polymer with diol; polyvinyl acetate, vinyl acetate Polyvinyl acetate resin such as coalescence; polyvinylacetal resin such as polyvinylacetal and polyvinylbutyral; epoxy resin as shown below, ketone resin as shown below, linear form of alkylene diisocyanate and alkylenediol Examples thereof include polyurethane resin as shown below, and it is preferable to contain at least one selected from these forces. As epoxy resin, a compound having two or more epoxy groups in one molecule forms a resin by a ring-opening reaction, and examples thereof include the following epoxy resins. Typical commercial products are Alraldide EPN1179 and Alaldide AER260 (manufactured by Asahi Chino Co., Ltd.). It should be noted that LARAL DIDE EPN 1179 has a weight average molecular weight of about 405. n represents the degree of polymerization.

[0077] [Chemical 1]

[0078] Further, the ketone resin is obtained by polymerizing vinyl ketones, and examples thereof include the following ketone resins. Typical commercial products include Hilac 110 and Hilac 110H ( Hitachi Chemical Co., Ltd.). n represents the degree of polymerization.

[0079] [Chemical 2] Hi rack 110

High rack 110H

[0080] With regard to the above-mentioned rosin, the present inventors have further devised a dispersion method as described below, so that they are outside the above weight average molecular weight range (less than 3,000, more than 90,000). In any case, it was found that the fine particle dispersibility can be improved and a fine particle dispersion can be formed with almost no aggregation.

 [0081] The above-mentioned rosin can be used without limitation on the weight average molecular weight, but the smaller the weight average molecular weight, the easier it is to use, and the weight average molecular weight is preferably in the range of about 300 to 40,000, 500 to More preferable than 20,000 power, 5,000 to 20,000 power ^ More preferable! The smaller the weight average molecular weight, the better the compatibility with the dope cellulose ester and the better the dispersibility of the fine particles, and the larger the fine particle dispersion, the more preferable the viscosity of the fine particle dispersion can be adjusted.

 [0082] (Dispersant)

The fine particle dispersion or dope used in the present invention preferably contains a dispersant. The addition amount of the dispersant is from 002 to 2 mass _^0/0 0. the cellulose ester is more preferably good Mashigu 0.01 to 1 mass%. As the dispersant, a polymer dispersant is particularly preferably used, and a non-one polymer dispersant, a char-on polymer dispersant, and a cationic polymer dispersant are appropriately selected.

[0083] In order to uniformly disperse solid fine particles in a solvent or a polymer composition solution, it is known that a polymer dispersant that adsorbs to the solid fine particles is used. The polymer dispersant forms an adsorption layer on the surface of the solid fine particles, and the powerful adsorption layer exerts repulsive force between the solid fine particles. This prevents the solid fine particles from aggregating. The polymer used as a polymer dispersing agent to disperse the fine particles includes a homopolymer composed of a single monomer, a random copolymer composed of a plurality of monomers, etc. In order to obtain good dispersion performance, Each molecule contains both a part that interacts and adsorbs with solid particles and a part that dissolves and spreads from the surface of solid particles into the liquid. In particular, polymer dispersants having a complicated structure have been devised, and specifically, comb polymers in which two powerful functions are shared are known as good polymer dispersants. In the present invention, these polymer dispersants are preferably contained in the dope or fine particle dispersion.

[0084] Examples of the polymer dispersant include a polymer dispersant described in general formula (I) or general formula (Π) in JP-A-2001-162934, a polymer dispersant described in JP-A-2004-97955, A mixture of an anionic polymer dispersant described in paragraph Nos. [0024] to [0027] of JP-A-2001-260265, a polyoxypropylene fatty acid alcohol compound described in JP-A-8-337560, and JP-A-9 — Polyoxypropylene fatty acid isopropanolamide mixture described in No. 20740, dispersant described in JP-A-9-192470, JP-A-9-313917, dispersant described in JP-A-11-197485, JP-A-2004-89787 Forces including listed dispersants and the like. It is not limited to these. Examples include F-1000, KF-1525, Hinoac Γ6000, 7000, 8000, 8000E, KM-1300M (manufactured by Kawaken Fine Chemical Co., Ltd.). In addition, polyethylene glycol, polypropylene glycol, polybutyl methyl ether, polyacetic acid butyl, polybulol alcohol, poly N-vinylpyrrolidone, poly (2-methyl-2-oxazoline), poly (2-ethyl-2-oxazoline), etc. Is mentioned.

 [0085] The content of the dispersant is preferably 0.0001 to 1% by mass in the dope or fine particle dispersion.

[0086] [Material for forming dope]

In the present invention, the dope is a solution containing a cellulose ester, an organic solvent, and fine particles having acicular and birefringence having a high acicular ratio, and this is used to cast a solution to form a cellulose ester film. It is to be formed. [0087] (cellulose ester)

 The cellulose used as a raw material for the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be used individually or in mixture in arbitrary ratios, respectively.

 [0088] In the cellulose ester according to the present invention, when the acylating agent of the cellulose raw material is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), an organic acid such as acetic acid such as methylene chloride is used. The reaction is carried out using an organic solvent and a protic catalyst such as sulfuric acid. When the acylating agent is acid chloride (CH COCl, C H COCl, C H COC1)

 3 2 5 3 7

 The reaction is carried out using a basic compound such as amine as a catalyst. Specifically, it can be synthesized by the method described in JP 10-45804. In the cellulose ester, the acyl group reacts with the hydroxyl group of the cellulose molecule. Cellulose molecules consist of many linked glucose units, with 3 hydroxyl groups per glucose unit. The number of substitutions of the acyl group at these three hydroxyl groups is called the degree of substitution. For example, cellulose triacetate has acetyl groups attached to all three hydroxyl groups of the glucose unit.

 [0089] The cellulose ester that can be used in the cellulose ester film preferably has a total acyl group substitution degree of 2.4 to 2.8.

 [0090] The molecular weight of the cellulose ester used in the present invention is a number average molecular weight (Mn) of 50,000 to 200,000. The power of 60,000-200,000 is more preferred <, 80,000-200,000 power is particularly preferred! / ヽ.

 [0091] The cellulose ester used in the present invention preferably has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio, MwZMn of 1.4 to 3.0 as described above. More preferably, it is in the range of 1.7 to 2.2.

 [0092] The average molecular weight and molecular weight distribution of the cellulose ester can be measured by a known method using high performance liquid chromatography. Using this, the number average molecular weight and the weight average molecular weight can be calculated, and the ratio (MwZMn) can be calculated.

 [0093] The measurement conditions are as follows.

[0094] Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Showa Denko Co., Ltd., 3 connected)

 Column temperature: 25 ° C

 Sample concentration: 0.1% by mass

 Detector: RI Model 504 (manufactured by GL Sciences)

 Pump: L6000 (manufactured by Hitachi, Ltd.)

 Flow rate: 1.0m mm

 Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosohichi Co., Ltd.) Mw = 1000000-500 It is preferable to use them at regular intervals.

 [0095] The cellulose ester used in the present invention is a carboxylic acid ester having about 2 to 22 carbon atoms, and is particularly preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. For example, cellulose acetate, cenorelose propionate, cenorelose butyrate, cellulose acetate phthalate, etc. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate petitate as described in 45804, 8-231761, U.S. Pat. No. 2,319,052 can be used. Alternatively, an ester of an aromatic carboxylic acid and cellulose and cellulose acylate described in JP-A Nos. 2002-179701, 2002-265639, and ^ 12002-265638 are also preferably used. Among the above-mentioned descriptions, the lower fatty acid esters of cellulose that are particularly preferably used are cellulose triacetate and cellulose acetate propionate. These cellulose esters can also be mixed and used.

 [0096] Preferred cellulose esters other than cellulose triacetate have an acyl group having 2 to 4 carbon atoms as a substituent, and the degree of substitution of the acetyl group is X, and the degree of substitution of the propiol group or petityl group is It is a cellulose ester that satisfies the following formulas (a) and (b) at the same time.

 [0097] Formula (a) 2. 4≤X + Y≤2.8

Formula (b) 0≤X≤2.5 When substituted with an acyl group, the moiety is usually present as a hydroxyl group. These can be synthesized by known methods.

 [0098] The degree of substitution of these acyl groups can be measured according to the method prescribed in ASTM-D817-96.

 [0099] In the case of acetyl cellulose, if the acetylation rate is to be increased, it is necessary to extend the time for the acetylation reaction. However, if the reaction time is too long, decomposition proceeds at the same time, and polymer chain scission causes decomposition of the acetyl group, leading to undesirable results. Therefore, it is necessary to set the reaction time within a certain range in order to increase the degree of acetylation and suppress degradation to some extent. It is not appropriate to specify the reaction time because the reaction conditions vary and greatly vary depending on the reactor, equipment and other conditions. As the degradation of the polymer progresses, the molecular weight distribution becomes wider, so in the case of cellulose ester, the degree of degradation can be defined by the value of the weight average molecular weight (Mw) Z number average molecular weight (Mn) that is usually used. That is, in the process of cellulose triacetate vinegar, the weight average molecular weight is an index of the degree of reaction that is too long and does not decompose too much and allows the vinegar to react for sufficient time for acetylation. (Mw) The value of Z number average molecular weight (Mn) can be used.

 [0100] An example of a method for producing a cellulose ester is shown below. Crushing 100 parts by weight of a fluffy printer as a cellulose raw material, adding 40 parts by weight of acetic acid, and activating pretreatment at 36 ° C for 20 minutes Did. Thereafter, 8 parts by mass of sulfuric acid, 260 parts by mass of acetic anhydride and 350 parts by mass of acetic acid were added, and esterification was performed at 36 ° C for 120 minutes. After neutralization with 11 parts by mass of a 24% by mass magnesium acetate aqueous solution, saponification aging was performed at 63 ° C. for 35 minutes to obtain acetyl cellulose. This was stirred for 160 minutes at room temperature with 10 times aqueous acetic acid solution (acetic acid: water = 1: 1 (mass ratio)), filtered and dried to obtain purified acetyl cellulose having a degree of acetyl substitution of 2.75. It was. This acetylcellulose had Mn of 92,000, Mw of 156,000, and Mw / Mn of 1.7. Similarly, cellulose esters having different degrees of substitution and MwZMn ratios can be synthesized by adjusting the esterification conditions (temperature, time, stirring) and hydrolysis conditions of the cellulose ester.

[0101] The synthesized cellulose ester is preferably purified to remove low molecular weight components or to remove unacetylated components by filtration. [0102] In the case of a mixed acid cellulose ester, it can be obtained by the method described in JP-A-10-45804. The method for measuring the degree of substitution of the acyl group can be measured in accordance with ASTM-D817-96.

 [0103] Cellulose esters are also affected by trace metal components in cellulose esters. These are thought to be related to water used in the manufacturing process, but metal ions such as iron, calcium, and magnesium are preferred to contain fewer components that can form insoluble nuclei. Insoluble matter may be formed by salt formation with a polymer degradation product or the like that may be lost, and it is preferable that the amount is small. The iron (Fe) component is preferably 1 ppm or less. The calcium (Ca) component is abundant in groundwater, river water, etc., and if it is too much, it becomes hard water and is also unsuitable as drinking water. Acidic components such as carboxylic acids and sulfonic acids, and many more It forms a complex with the ligand of, ie, a scum (insoluble starch, turbidity) derived from many insoluble calcium.

 [0104] The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. As for the magnesium (Mg) component, too much too much results in insoluble matter, so 0 to 70 ppm is preferable, and 0 to 20 ppm is particularly preferable. Metal components such as iron (Fe) content, calcium and a) content, and magnesium (Mg) content are pre-treated by microdigest wet cracking equipment (sulfuric acid decomposition) and alkali melting. Then, it can be obtained by performing analysis using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer).

 [0105] (Organic solvent)

Organic solvents that dissolve cellulose esters and are useful for forming cellulose ester solutions or dopes include chlorinated organic solvents and non-chlorinated organic solvents. Examples of the chlorinated organic solvent include methylene chloride (methylene chloride), which is suitable for dissolving cellulose esters, particularly cellulose triacetate. Due to recent environmental problems, the use of non-chlorine organic solvents is being investigated. Non-chlorine organic solvents include, for example, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolan, 1,4-dioxan, cyclohexanone, ethynole formate, 2, 2, 2-trifanol. Year old Roetanore, 2, 2, 3, 3- Hexafluoro-1-propanol, 1,3 difluoro-2-propanol, 1,1,1,3,3,3 Hexafnoroleol 2-Methylolone 2 Prono Norole, 1, 1, 1, 3, 3, 3 Hexafluoro-2-propanol 2, 2, 3, 3, 3 pentafluoro-1-propanol, nitroethane and the like. When these organic solvents are used for cellulose triacetate, a dissolution method at room temperature can be used. However, by using a dissolution method such as a high-temperature dissolution method, a cooling dissolution method, or a high-pressure dissolution method, It is preferable because it can be reduced. For cellulose esters other than cellulose triacetate, methyl acetate, ethyl acetate, and acetone are preferably used. Particularly preferred is methyl acetate. In the present invention, an organic solvent having good solubility in the cellulose ester is a good solvent, and a main effect is shown in the dissolution, and an organic solvent used in a large amount is a main (organic) solvent or a main solvent. It is called (organic) solvent.

 [0106] The dope according to the present invention preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent. These are gels that after casting the dope onto a metal support, the solvent begins to evaporate and the dope film (web) gels when the proportion of alcohol increases, making the web strong and easy to peel off from the metal support. It is also used as a chlorinated solvent, and when these ratios are low, it also has a role of promoting the dissolution of cellulose esters as non-chlorine organic solvents. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec butanol and tert-butanol. Of these, ethanol is preferable because it has excellent dope stability, has a relatively low boiling point, and has good drying properties. These organic solvents alone are soluble in cellulose esters and are therefore poor solvents.

[0107] The concentration of the cellulose ester 15-30 weight in the dope _^0/0, doped viscosity preferable for it to be prepared in a range of 100 to 500 Pa 's to obtain a good film surface quality.

[0108] Additives added to the dope include plasticizers, ultraviolet absorbers, antioxidants, dyes, fine particles, and the like. In the present invention, additives other than fine particles may be added during the preparation of the cellulose ester solution, or may be added during the preparation of the fine particle dispersion. The polarizing plate used in the liquid crystal image display device has a plasticizer, acid, It is preferable to add anti-oxidation agents and UV absorbers. The additive will be described below.

[0109] (Plasticizer)

 In the cellulose ester solution or dope according to the present invention, a compound known as a plasticizer is used for the purpose of improving mechanical properties, imparting flexibility, imparting water absorption resistance, reducing water vapor permeability, adjusting retardation, etc. For example, phosphate ester carboxylate is preferably used.

[0110] Examples of the phosphoric acid ester include triphenyl phosphate, tricresyl phosphate, and phenyl diphosphate.

[0111] Examples of the carboxylic acid ester include phthalic acid esters and citrate esters. Examples of the phthalic acid esters include dimethyl phthalate, jetyl phosphate, dioctyl phthalate, and jetyl hexyl phthalate. Mention may be made of cetyl cetyl and acetyl butyl thioate. Other examples include butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, and triacetin. Alkylphthalylalkyl glycolates are also preferably used for this purpose. The alkyl in the alkylphthalylalkyl glycolate is an alkyl group having 1 to 8 carbon atoms. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl dallicoleate, ethyl phthalyl ethyl dallicolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl dallicolate, octyl phthalyl octyl dallicolate, methyl phthalyl Ethyl dallicolate, Ethyl phthalyl methyl dallicolate, Ethyl phthalyl propyl glycolate, Propyl phthalyl ethyl dallicolate, Methyl phthalyl propyl glycolate, Methyl phthalyl butyl dallicolate, Ethyl phthalyl butyl dallicolate , Butyl phthalyl methyl glycolate, butyl phthalyl ethyl dalicolate, propyl phthalyl butyl gallate, butyl phthalyl propyl glycolate, methyl phthalyl octyl dalicolate, ethyl phthalyl Glycolyl acrylate, octyl phthalyl methyl dallicolate, octyl phthalyl ethyl dallicolate, etc., such as methyl phthalyl methyl dallicolate, ethyl phthalyl ethyl dallicolate, propyl phthalyl propyl glycolate, butyl phthalyl Butyl glycolate and octyl phthalyl octyl dalicolate are preferably used. Two or more of these alkylphthalylalkyl glycolates may be used in combination. [0112] Polyhydric alcohol esters are also preferably used.

 [0113] The polyhydric alcohol used in the present invention is represented by the following general formula (1).

 [0114] General formula (1) Rl-(OH)

 R1 represents an n-valent organic group, n represents a positive integer of 2 or more, an OH group represents an alcoholic group, and Z or a phenolic hydroxyl group.

 [0115] The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a divalent or higher aliphatic polyhydric alcohol and monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester

[0116] Examples of preferable polyhydric alcohols include, for example, the following. The present invention is not limited to these. Aditol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1, 2 propanediol, 1, 3 propanediol, dipropylene glycol, tripropylene glycol, 1,2 butanediol, 1, 3 Butanediol, 1,4 Butanediol, Dibutylene glycol, 1,2,4 Butanetriol, 1,5 Pentanediol, 1,6 Hexanediol, Hexanetriol, Galactitol, Mannitol, 3-Methylpentane 1, 3, 5 Examples include triol, pinacol, sorbitol, trimethylol bread, trimethylolethane, and xylitol. In particular, triethylene glycol, tetraethylenedaricol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

 [0117] As the monocarboxylic acid used in the polyhydric alcohol ester, known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like, which are not particularly limited, can be used. Use of alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

 [0118] Examples of preferable monocarboxylic acids include the following. The present invention is not limited thereto.

[0119] As the aliphatic monocarboxylic acid, a straight-chain or side-chain fatty acid having 1 to 32 carbon atoms can be preferably used. It is even more preferred that the carbon number is 1-20. Especially preferred to be. When acetic acid is contained, the compatibility with the cellulose ester increases, so that it is also preferable to use a mixture of acetic acid and other monocarboxylic acid.

 [0120] Preferably, the aliphatic monocarboxylic acid includes acetic acid, propionic acid, butyric acid, valeric acid, cabronic acid, enanthic acid, strength prillic acid, pelargonic acid, strength puric acid, 2-ethyl hexanoic acid, undecyl. Acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, araquinic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, rataceric acid, etc. And unsaturated fatty acids such as saturated fatty acid, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

 [0121] Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

 [0122] Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and benzene such as biphenylcarboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. An aromatic monocarboxylic acid having two or more rings, or a derivative thereof can be exemplified. Benzoic acid is particularly preferable.

 [0123] The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, more preferably 350 to 750. Smaller molecular weights are preferred in terms of moisture permeability and compatibility with cellulose esters, as higher molecular weights are less likely to volatilize.

 [0124] The carboxylic acid used in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Further, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

[0125] These compounds, 1 to the cellulose ester 30 mass _^0/0, preferably is preferably contained so as to be 1 to 20 mass%. In order to suppress bleeding out during stretching and drying, a compound having a vapor pressure at 200 ° C. of 1400 Pa or less is preferable.

[0126] These compounds are used in the preparation of a cellulose ester solution. It may be added together with a solvent, or may be added during or after solution preparation.

 [0127] Other additives include polyesters and polyester ethers described in JP-A-2002-22956, urethane resins described in JP-A-2003-171499, rosins and rosin derivatives described in JP-A-2002-146044 , Epoxy resin, ketone resin, toluenesulfonamide resin, ester of polyhydric alcohol and carboxylic acid described in JP-A No. 2003-96236, combination of formula (1) described in JP-A No. 2003-165868 And polyester polymers or polyurethane polymers described in JP-A No. 2004-292696. These additives can be contained in a dope or fine particle dispersion.

 [0128] (UV absorber)

 The cellulose ester film of the present invention can contain an ultraviolet absorber. Examples of ultraviolet absorbers that can be used include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like. The ability to mention benzotriazole compounds with little coloration are preferred. Further, ultraviolet absorbers described in JP-A Nos. 10-182621, 8-337574, and 2001-72782, JP-A-6-148430, JP-A-2002-31715, JP-A-2002-169020, and 2002. — Polymer ultraviolet absorbers described in 47357, 2002-363420, 2003-113317 are also preferably used. As an ultraviolet absorber, it has excellent absorption of ultraviolet light with a wavelength of 370 nm or less from the viewpoint of preventing the deterioration of polarizers and liquid crystals, and from the viewpoint of liquid crystal display, it absorbs less visible light with a wavelength of 400 nm or more! /, I like things! /

[0129] Specific examples of ultraviolet absorbers useful in the present invention include 2- (2'-hydroxymonomethylphenol) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert- Butylphenol) benzotriazole, 2— (2 ′ —hydroxy—3 ′ —tert—butyl—5′-methylphenol) benzotriazole, 2— (2 ′ —hydroxy—3 ′, 5′—di—tert —Butylphenol) 1-5 Chronobenzozoazole, 2— (2 ′ —Hydroxy 1 3 ′ — (3, “, 5 Q” —Tetrahydrophthalimidomethyl) 5, —Methylphenyl) benzotriazole, 2, 2-Methylenebis (4- (1,1,3,3-tetramethylbutyl) 6- (2H-benzotriazole-2-yl) phenol), 2- (2'-hydroxy 3'-tert-butyl) 5'-methylphenol) 5 Chronobenzozoazole, 2- (2H benzotriazol-2yl) -6 (straight and side chain dodecyl) -4 methylphenol, octyl —3— [3-tert butyl 4 Hydroxy-5- (black-mouthed 2H benzotriazole-2-phenyl) phenol] propionate and 2-ethylhexyl 3- [3-tert-butyl 4-hydroxy 5-- (5 black-mouthed 2H benzotriazole-2 (Fill) [Fail] propionate, and the like, but is not limited thereto. As commercially available products, TINUVIN 109, TINUVIN 171 and TINUVIN 326 (all manufactured by Ciba Specialty Chemicals) can be preferably used. As an example of the polymer ultraviolet absorber, a reactive ultraviolet absorber RUVA-93 manufactured by Otsuka Chemical Co., Ltd. can be given as an example.

 [0130] Specific examples of benzophenone compounds include 2,4 dihydroxybenzophenone, 2, 2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-1-methoxy-1-5-sulfobenzophenone, bis (2 methoxy 4 Hydroxy 5 benzoylmethane) and the like, but is not limited thereto.

 [0131] The ultraviolet absorber described above preferably used in the present invention is a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber excellent in the effect of preventing deterioration of a highly transparent polarizing plate or liquid crystal element. Benzotriazole-based ultraviolet absorbers are particularly preferably used because they have less unwanted coloration that is preferred by the agent.

 [0132] The method of adding the UV absorber to the dope is a power that can be used without limitation as long as the UV absorber can be dissolved in the dope. In the present invention, the UV absorber is a methylene chloride, acetic acid. Cellulose ester solution as a UV absorber solution by dissolving in a good solvent for cellulose esters such as methyl and dioxolane, or in a mixed organic solvent of a good solvent and a poor solvent such as lower aliphatic alcohol (methanol, ethanol, propanol, butanol, etc.) The method of adding to the dope is preferred. In this case, it is preferable to make the dope solvent composition and the solvent composition of the UV absorber solution as close as possible to each other. The content of the ultraviolet absorber is from 0.01 to 5% by weight, in particular from 0.5 to 3% by weight.

 [0133] (Antioxidant)

As the anti-oxidation agent, a hindered phenol compound is preferably used. 2,6 di-tert-butyl-p-taresole, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenol) propionate], triethylene glycol bis [3- (3-tert-butyl-5- Methyl-4-hydroxyphenol) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenol) propionate], 2,4bis (n— Octylthio) -6- (4-hydroxy 3,5 di-tert-butyl-lino) 1, 3, 5 triazine, 2, 2 thiodiethylenebis [3- (3,5-di-tert-butyl 4-hydroxyphenol- ) Propionate], octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenol) propionate, N, N'-hexamethylenbis (3,5 di-tert-butyl 4-hydroxy monohydrosine Namamide), 1, 3, 5 Increment Chiru 2, 4, 6-tris (3, 5-di-t-butyl-4-hydroxybenzyl) benzene, Doo squirrel one (3, 5-di one t- butyl 4-hydroxybenzyl) Single Isoshianureito etc. like et be. In particular, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3 (3-, 5-di-tert-butyl-4-hydroxyphenol) propionate], triethylene glycol-bis [3- (3-t Butyl-5-methyl-4-hydroxyphenol) propionate] is preferred. Also, for example, hydrazine-based metal deactivators such as N, N'-bis [3- (3,5-di-tert-butyl 4-hydroxyphenyl) propiol] hydrazine, tris (2,4- It is also possible to use phosphorus-based processing stabilizers such as di (tbutylbutyl) phosphite. The amount of addition of these compounds is preferably lppm to l.0% by weight with respect to the cellulose ester, more preferably 10 to 1 OOOppm.

[0134] (Matting agent)

 In the present invention, in addition to the needle-like fine particles having birefringence, fine particles can be further contained in the cellulose ester film as a matting agent. This makes it easy to carry and take up.

[0135] The particle size of the matting agent is preferably primary particles or secondary particles of 10 nm to 0.1 µm. A substantially spherical matting agent having a primary particle acicular ratio of 1.1 or less is preferably used.

[0136] As the fine particles, those containing silicon are preferred, and silicon dioxide is particularly preferred. Preferred examples of the silicon dioxide fine particles used in the present invention include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, 0X50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). As mentioned above, those commercially available under the trade name of Nippon Aerosil Co., Ltd. can be mentioned, and Aerogenole 200V, R972, R972V, R974, R202, R812 can be preferably used. Examples of polymer fine particles include silicone resin, fluorine resin and acrylic resin. Silicone resin is preferred, particularly those having a three-dimensional network structure.For example, Tosnowl 103, 105, 108, 120, 145, 3120 and 240 (Toshiba Silicone) (Manufactured by Co., Ltd.).

 [0137] The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 gZL or more. An average primary particle size of 5 to 16 nm is more preferred, and 5 to 12 nm is more preferred. The average primary particle size is smaller, and haze is preferred. The apparent specific gravity is preferably 90 to 200 gZL or more, more preferably 100 to 200 gZL or more. Higher apparent specific gravity makes it possible to produce a high-concentration fine particle dispersion and does not generate haze or aggregates.

[0138] The amount of the matting agent added in the present invention is preferably 0.01 to 1. Og force, more preferably 0.03 to 0.3 g force, and 0.08 to 0.16 g force per lm ^{2 of} the cellulose ester film. I like it even more!

 [0139] (Surfactant)

The dope or fine particle dispersion used in the present invention preferably contains a surfactant, and is not particularly limited to phosphoric acid, sulfonic acid, carboxylic acid, non-one, cationic and the like. These are described, for example, in JP-A-61-243837.添Ka卩量of interfacial active agent, preferably is from 0.002 to 2 mass _^0/0 to cellulose § shea rate instrument 0.01 to 1 mass% is more preferable. If the addition amount is less than 0.001% by mass, the effect of addition cannot be fully exerted, and if the addition amount exceeds 2% by mass, precipitation or insoluble matter may occur.

[0140] The non-ionic surfactant is a surfactant having a non-ionic hydrophilic group of polyoxyethylene, polyoxypropylene, polyoxybutylene, polyglycidyl sorbitan. Oxyethylene alkyl ether, polyoxyethylene alkyl ether, polyoxyethylene monopolyoxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester ,fatty acid Examples include diethanolamide and triethanolamine fatty acid partial esters.

 [0141] As the cation surfactant, carboxylate, sulfate, sulfonate, phosphate ester salt, and representative examples include fatty acid salt, alkylbenzene sulfonate, alkyl naphthalene sulfonate. Salt, alkyl sulfonate, a-olefin sulfonate, dialkyl sulfosuccinate, α-sulfonated fatty acid salt, Ν-methyl-oleyl taurine, petroleum sulfonate, alkyl sulfate, sulfate Fats and oils, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, naphthalene sulfonate form And aldehyde condensates.

 [0142] Examples of cationic surfactants include ammine salts, quaternary ammonium salts, pyridium salts, etc., and primary to tertiary fatty amine salts, quaternary ammonium salts ( Tetraalkyl ammonium salts, trialkylbenzam salts, alkyl pyridinium salts, alkyl imidazolium salts, and the like. Examples of amphoteric surfactants include carboxybetaine and sulfobetaine, such as Ν-trialkyl-Ν-carboxymethylammonium betaine and 、 -trialkylΝsulfoalkylene ammonium betaine. The fluorosurfactant is a surfactant having a fluorocarbon chain as a hydrophobic group. Fluorosurfactants include C F CHCHO— (CHCHO) — OSO Na, C F SO

 8 17 2 2 2 2 10 3 8 17

N (CH) (CH CH O) H, C F SO N (C H) CH COOK, C F COONH,

2 3 7 2 2 16 8 17 2 3 7 2 7 15 4

C F SO N (C H) (CH CH O)-(CH) —SO Na ゝ C F SO N (C H) (CH)

8 17 2 3 7 2 2 4 2 4 3 8 17 2 3 7 2 3

— N + (CH) -I—, CF SO N (CH) CH CH CH N ⁺ (CH) — CH COO—, CFC

 3 3 8 17 2 3 7 2 2 2 3 2 2 8 17

HCHO (CHCHO) — H, CF CHCHO (CH) — N + (CH) · Ι \ H (CF)

2 2 2 2 16 8 17 2 2 2 3 3 3 2 8

CH CH OCOCH CH (SO) COOCH CH CH CH (CF) H, H (CF) CH C

 2 2 2 3 2 2 2 2 2 8 2 6 2

H 0 (CH CH O) H, H (CF) CH CH O (CH) N + (CH) Γ, H (CF) C

2 2 2 16 2 8 2 2 2 3 3 3 2 8

H CH OCOCH CH (SO) COOCH H CH CH C F, C F-C H-SO N (C

2 2 2 3 2 2 2 2 8 17 9 17 6 4 2 3

H) (CH CH O) H, CF -CH CSO N (C H) (CH) N + (CH)

7 2 2 16 9 17 6 4 2 3 7 2 3 3 3 is not limited to these forces.

[0143] (Peeling accelerator) Furthermore, a peeling accelerator for reducing the load during peeling may be added to the dope. Of these, surfactants are effective, and there are phosphoric acid-based, sulfonic acid-based, carboxylic acid-based, non-ionic, cationic and the like, but not limited thereto. These stripping accelerators

For example, it describes in Unexamined-Japanese-Patent No. 61-243837 etc. Japanese Laid-Open Patent Publication No. 57-500833 discloses polyethoxylated phosphate ester as a release accelerator. JP 61-69

No. 845 discloses that the monoester or diphosphate alkyl ester in which the non-esterified hydroxy group is in the form of a free acid can be rapidly removed by adding to the cellulose ester. JP-A-1-299847 discloses that the release load can be reduced by adding a phosphate ester compound containing an unesterified hydroxyl group and a propylene oxide chain and inorganic particles.

 [0144] It is also preferable that the compound represented by the following formula (2) or (3) is included!

 [0145] (2) (R -B -0) P (= 0) — (OM)

 1 1 nl 1 n2

 (3) R B -X

 twenty two

 In the formula, R and R are each a substituted or unsubstituted alkyl group having 4 to 40 carbon atoms,

 1 2

 An alkyl group, an aralkyl group or an aryl group; M is an alkali metal, an ammonium group;

1

 , Lower alkylamine; B and B are each a divalent linking group; X is a force

 1 2

 Rubonic acid or a salt thereof, sulfonic acid or a salt thereof, or a sulfate ester or a salt thereof; nl is 1 or 2; and n2 is 3-nl.

[0146] The cellulose acylate film contains at least one release agent represented by the formula (2) or (3). Hereinafter, these release agents will be described. R and R

Preferred examples of 1 2 include substituted and unsubstituted alkyl groups having 4 to 40 carbon atoms (for example, butyl, hexyl, octyl, 2-ethylhexyl, nonyl, dodecyl, hexadecyl, octadecyl, eicosal). , Docosal, myricyl, etc.), substituted with 4 to 40 carbon atoms, unsubstituted alkenyl group (for example, 2 hexyl, 9-decyl, oleyl, etc.), with 4 to 40 carbon atoms Substituted or unsubstituted aryl groups (eg, phenyl, naphthyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethenylphenyl, propylphenyl, diisopropylphenyl, triisopropylphenyl, t-butylphenyl, di-t-butylphenyl, tree t butyl phenyl, isopentyl phenyl, octyl phenyl, isooctyl phenyl, O

 1 Ionol, diisanol, dodecyl, and isopentadecyl)

 [0147] Among these, more preferable examples of alkyl include hexyl, octyl, 2-ethylhexyl, nonyl, dodecyl, hexadecyl, octadecyl, docosayl, and alkaryl as oleyl and aryl groups. Is phenyl, naphthyl, trimethylphenyl, diisopropylpropyl, triisopropylphenyl, di-t-butylphenyl, tri-tert-phenylphenyl, iso-octylphenyl, iso-phenol, di-iso-phenol, dodecy Rufisopentadecyl fail.

 [0148] Next, the divalent linking group of B and B will be described. C1-C10 alkylene, poly (

 1 2

 Degree of polymerization 1-50) oxyethylene, poly (degree of polymerization 1-50) oxypropylene, poly (degree of polymerization 1-50) oxyglycerin, and a mixture thereof. Preferred linking groups among these are methylene, ethylene, propylene, butylene, poly (degree of polymerization 1 to 25) oxchethylene, poly (degree of polymerization 1 to 25) oxypropylene, poly (degree of polymerization 1 to 15) oxyglycerin. It is.

 [0149] Next, X is carboxylic acid (or salt), sulfonic acid (or salt), sulfate ester (or salt), particularly preferably sulfonic acid (or salt) or sulfate ester (or salt). It is. Preferred salts are Na, K, ammonia, trimethylamine and triethanolamine. Specific examples of preferred compounds of the present invention are described below.

 -1 C Η 0-Ρ (= 0)-(ΟΗ)

 RZ- -2 H 0-P (= 0)-(OK)

 RZ- -3 (OK)

 RZ- -44 C H (OCHCH) 0-P (= 0)-(OK)

 31 2 2 5 2

 RZ- -55 {C H O (CHCHO)} -P (= 0) -OH

 RZ- -6

 18 35 2 2 8 2

 RZ- -7 i) -CH -OCH CH 0-P (= 0)-(OK)

 9 3 6 2 2 2 2

 RZ- -8 H -CH -0- (CH CH O) -P (= 0)-(OK) (OH)

RZ- -9

 12 25

 RZ- -10

12 25 RZ- 11 CH COOH

 17 33

 RZ- 12 C H COOH-N (CH CH OH)

 17 33 2 2 3

 RZ- 13 iso-C H -C H -O- (CH CH O)-(CH) SO Na

 twenty three

H) SO Na

 RZ-16 Tri-t-Butyl naphthalene sodium sulfonate

 RZ- 17 C H CON (CH) CH CH SO Na

 17 33 3 2 2 3

 RZ- 18 C H C H SO -NH

 12 25 6 4 3 4

 The amount of these compounds used is preferably 0.002 to 2% by mass in the dope. More preferably, the content is 0.005 to 1% by mass, and still more preferably 0.01 to 0.5% by mass. The addition method is not particularly limited, but it may be liquid or solid as it is and added together with other materials before dissolution, or may be added later to a cellulose acylate solution prepared in advance. By containing these, it becomes easy to align the fine particles.

 [0151] (Other additives)

 In addition, thermal stabilizers such as inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, acidic titanium, and alumina, and alkaline earth metal salts such as calcium and magnesium can be added. Good. In addition, antistatic agents, flame retardants, lubricants, oils, etc. may be added.

 [0152] [Solution casting film forming method]

 The cellulose ester film of the present invention is formed by a solution casting film forming method. Here, the solution casting film forming method will be described with reference to FIG.

 FIG. 6 is a diagram showing an example of a process schematically showing the dope preparation process, casting process and drying process of the solution casting film-forming method according to the present invention.

[0154] (1) Fine particle dispersion preparation process

 The method for preparing the fine particle dispersion of the present invention is not particularly limited, but is preferably performed by the following method a) or b)!

[0155] a) An organic solvent and a fine particle-dispersed resin are introduced into a dissolving kettle and dissolved by stirring to obtain a resin solution. The Separately, the mixture of organic solvent and fine particles is transferred to a disperser such as Menton Gorley or Sand Mill by a liquid feed pump and pre-dispersed. This is added to the above-mentioned rosin solution, stirred and agglomerated with a filter to remove agglomerates and stocked as a fine particle dispersion (slightly different from FIG. 6). The prepared fine particle dispersion may be further repeatedly dispersed and filtered several times.

 [0156] b) An organic solvent and resin are added to a dissolving kettle, and dissolved by stirring to obtain a resin solution. Fine particles are collected in this resin solution, and a disperser such as Manton Gorin or a sand mill (not shown) ) And sent to a filter with a liquid feed pump to remove aggregates and make a fine particle dispersion (the same operation may be repeated several times). Then, the fine particle dispersion is transferred from the switching valve to the stock tank, and after standing and defoaming, transferred by a liquid feed pump (for example, a pressurized metering gear pump), filtered by a filter and transferred by a conduit.

 [0157] A plasticizer, a purple ray absorbent, a dispersant and the like may be further added to the fine particle dispersion.

 [0158] Dispersers used in preparing the fine particle dispersion as described above of the present invention are roughly divided into a medialess disperser and a media disperser, and both can be used.

[0159] Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. In the present invention, a high pressure disperser is preferably used. A high-pressure dispersion device is a device that creates special conditions such as high shear and high-pressure conditions by passing a mixture of fine particles and solvent through a narrow tube at high speed. It is preferable that the maximum pressure condition inside the apparatus is 9.8 × 10 ⁶ Pa or more in a tube having a tube diameter of 1 to 2000 / ζ πι, for example, by treating with a high-pressure dispersion apparatus. More preferably, it is 19.6 × 10 ⁶ Pa or more. At that time, it is preferable that the maximum reaching speed reaches lOOmZsec or more, and the heat transfer speed reaches lOOkcalZhr or more. The above-mentioned high-pressure disperser includes an ultra-high pressure homogenizer manufactured by Microfluidics Corporation (trade name: Microfluidizer 1), Nanomizer 1 manufactured by Nanomizer 1 and Ultra Ratarax, and other Manton Gorin type Examples thereof include a high-pressure dispersing device such as Izumi Food Machinery's homogenizer, Sanwa Kikai Co., Ltd. UHN-01.

 [0160] Examples of the media disperser include a ball mill, a sand mill, and a dyno mill that disperse using the collision force of media such as glass beads and ceramic beads. In the present invention, a media disperser is particularly preferably used.

[0161] Beads having a bead diameter of 0.03 to 0.3 mm are preferably used. . Those dispersed with beads having a diameter in this range are preferably used because it is difficult to form a mass of acicular fine particles in the dope.

 [0162] The fine particle dispersion prepared in this manner removes aggregates and foreign matters by filtration. A dope is prepared using the obtained fine particle dispersion.

 [0163] (2) Cellulose ester solution preparation process

 In the present invention, a dope is prepared by mixing a fine particle dispersion prepared in advance by the above method, a solvent, and cellulose ester. Specifically, it is preferable that a part of the solvent and the fine particle dispersion are added and mixed in the dissolution vessel, and then the remaining solvent and the cellulose ester are added and dissolved therein with stirring. Even if an additive such as a plasticizer has been added to the melting pot in advance, it can be added to the melt.

 [0164] Alternatively, an additive such as cellulose ester or a plasticizer may be added to the solvent in the dissolution vessel without stirring, and the fine particle dispersion may be further added during dissolution of the cellulose ester. Alternatively, a cellulose ester solution can be obtained by mixing a solvent and an additive such as cellulose ester and a plasticizer, and the fine particle dispersion can be added thereto with stirring.

 [0165] The method for preparing the cellulose ester solution will be described in more detail.

[0166] Additives such as cellulose ester and plasticizer are dissolved in an organic solvent mainly composed of the above-mentioned good solvent for cellulose ester while stirring. For dissolution, a method under normal pressure, a method below the boiling point of the main solvent, a high-temperature dissolution method under pressure above the boiling point of the main solvent, a cooling dissolution method with cooling and dissolution, and a high-pressure dissolution at a fairly high pressure Although there are various dissolution methods such as methods, the high temperature dissolution method is preferably used in the present invention.

[0167] The cellulose ester solution obtained by mixing the fine particle dispersion, the cellulose ester, and the solvent in the dissolution vessel is dissolved in the cellulose ester and then sent to a filter by a pump and filtered.

[0168] The filtration is preferably carried out using this cellulose ester solution with an appropriate filter medium such as filter paper for filter press. The filter medium in the present invention has a low absolute filtration accuracy to remove insoluble matters and the like! However, if the absolute filtration accuracy is too small, there is a problem that the filter media is likely to be clogged. A filter media with an absolute filtration accuracy of 8 m or less is preferred. A filter medium in the range of 1 to 8 / ζ πι is more preferable. A filter medium in the range of 3 to 6 m is more preferable. Examples of the filter paper include No. 244 and 277 of Azumi Filter Paper Co., Ltd., which are commercially available, and are preferably used.

[0169] The filter material used for filtration can be an ordinary filter medium with no particular restrictions. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel are used to remove the fibers. Etc. are preferred. Filtration can be performed by a normal method, but the method of filtering while heating or holding at a temperature that is higher than the boiling point of the organic solvent used at normal pressure and in a range where the organic solvent does not boil is the filter medium. The increase in the differential pressure before and after (hereinafter sometimes referred to as filtration pressure) is preferably small. The preferred temperature range depends on the organic solvent used, but is 45 to 120 ° C, more preferably 45 to 55 ° C, more preferably 45 to 70 ° C. It is preferable that the filtration pressure is small, preferably 0.3 to 1.6 MPa, more preferably 0.3 to 1.2 MPa, and further 0.3 to 1. OMPa. preferable.

 [0170] The dope thus obtained is stored in a stock tank, defoamed, and used for casting.

[0171] In this way, it is preferable to prepare the dope by mixing the fine particle dispersion and the cellulose ester solution in the dope kettle, and the power mentioned as the method may be part or all of the cellulose ester solution and the fine particle dispersion. Can also be mixed in-line. For example, FIG. 6 shows an example of a process for adding a fine particle dispersion in-line. The fine particle dispersion is joined with a cellulose ester solution (or may be referred to as a dope stock solution) in a joining pipe 20. Immediately before the junction pipe 20, a filter is disposed. For example, a lump containing acicular fine particles or a large foreign matter generated from a path associated with filter medium exchange or the like is dispersed in the fine particle dispersion or dope in the liquid feed. It can be removed from the stock solution. Here, a metal filter having solvent resistance is preferably used. The filter medium is preferably a metal from the viewpoint of durability, particularly stainless steel. From the viewpoint of clogging, it is preferable to have a porosity of 60 to 80%. Most preferably, the filtration is performed with a metal filter medium having an absolute filtration accuracy of 30 to 60 m and a porosity of 60 to 80%, so that coarse foreign matters can be reliably removed over a long period of time. This is preferable. Metal with absolute filtration accuracy of 30-60 μm and porosity of 60-80% Examples of the filter material include NF-10, NF-12, and NF-13 of Finepore NF series manufactured by Nippon Seisen Co., Ltd.

 [0172] In the present invention, the absolute filtration accuracy is defined as follows. Put glass beads and pure water of test powders with different particle diameters specified in JIS Z 8901 in a beaker, and perform suction filtration with an apparatus as shown in Fig. 7 while stirring with a stirrer. FIG. 7 is a diagram schematically showing an apparatus for measuring absolute filtration accuracy. Here, A represents a filter medium sample to be measured, B represents a filtrate, and C represents a filtrate. The filtrate to be filtered B is stirred with a stirrer S, and is filtered with a low pressure vacuum pump P from atmospheric pressure to -4 kPa. V is a valve that can be opened and closed, and M is a manometer. At this time, the number of glass beads in the filtrate B and filtrate C is observed with a microscope, and the particle collection rate is obtained by the following formula. The particle size when the particle collection rate was 95% was defined as absolute filtration accuracy.

 [0173] Particle collection rate (%) = (number in the filtrate-number in the filtrate) Z (number in the filtrate)

 X 100

 The porosity of the filter medium is preferably 60 to 80%, more preferably 65 to 75%. A larger porosity is preferable because it has a higher pressure loss and a smaller porosity, which is preferable in terms of decreasing pressure. To determine the porosity, first immerse the filter medium in a solvent with low surface tension, remove the air in the filter medium, calculate the amount of pores in the filter medium from the increased amount of solvent, and divide by the volume of the filter medium. can do.

[0174] (3) In-line addition process

In the case of preparing a dope by mixing a squeezed fine particle dispersion, a cellulose ester and a solvent in a dissolution vessel, it is usually unnecessary to add the fine particle dispersion in-line. However, if necessary, all or a part of the fine particles can be mixed in-line. Referring to FIG. 6, the in-line addition process is described. A cellulose ester solution (sometimes referred to as a dope stock solution) and a fine particle dispersion are transferred by liquid feed pumps 5 and 14, respectively, and filtered by filters 6 and 15. Transfer through conduits 8 and 16 and join the two liquids in the merge pipe 20. Since the combined liquids are transported in layers in the conduit, they are difficult to mix as they are. Therefore, after the two liquids merge, they are transferred to the next process while being sufficiently mixed by the mixer 21 such as an in-line mixer. Examples of the in-line mixer that can be used in the present invention include a static mixer. I prefer SWJ (Toray Static In-Pipe Mixer Hi-Mixer, manufactured by Toray Engineering)! / ヽ

[0175] In the present invention, the film is stretched in any of the drying steps described below, and the birefringence of the stretched film is measured. The measurement result of the birefringence causes needle-like birefringence contained in the dope. It is preferable to adjust the content of the fine particles. In other words, when it is confirmed that the measurement result of birefringence deviates from the desired birefringence value, it is considered that the cause is that the content of fine particles is low. It is preferable to add fine particles to the dope stock solution to compensate for this. An in-line addition process is preferably used as a method for adding the fine particles to the dope stock solution. Specifically, there is a method of adjusting the content of needle-shaped birefringent fine particles in the dope by adding a fine particle dispersion having needle-like birefringence in-line to the dope. Specifically, it can be added by a method using the in-line mixer. The fine particle dispersion prepared by the above-described method can be used as it is for the fine particle dispersion added in-line (this may be referred to as an in-line additive). Alternatively, a solution in which a solvent, a cellulose ester solution, other additives, and the like are further added to adjust the fine particle concentration and the cellulose ester concentration can be used as the in-line additive solution. The in-line additive solution preferably includes fine particles at a concentration of 1.1 to 50 times the fine particle concentration in the dope used for casting.

 [0176] The birefringence of the stretched film was measured, and the fine particle content in the dope was adjusted by increasing or decreasing the addition amount of the fine particle additive liquid according to the measurement result of the birefringence. The birefringence value of the stretched film is preferably controlled to a desired value. The fine particle content in the dope can be increased or decreased by changing the mixing ratio between the fine particle additive solution and the dope stock solution. To change the mixing ratio, change the ratio of the feed volume of the fine particle additive solution to the dope stock solution.

[0177] In the dope prepared by the step (2) or the steps (2) and (3), it is preferable to adjust the solid content concentration in the dope to 15% by mass or more, particularly 18 to 30% by mass. Is preferred. If the solids concentration in the dope is too high, the viscosity of the dope becomes too high, and there is a case where the film flatness is deteriorated due to the occurrence of a sheer skin or the like during casting. It is desirable.

 [0178] (4) Casting process

 The dope prepared up to the previous step is fed to the die 30 and transferred to an endless metal support 31, for example, a stainless steel belt, or a metal support 31 such as a rotating metal drum. This is a process of casting a dope from the die 30. The surface of the metal support 31 is a mirror surface. A die 30 (for example, a pressure die) is preferable because the slit shape of the die portion can be adjusted and the film thickness can be uniformly blocked. The die 30 includes a coat hanger die and a T die, and any of them is preferably used. In order to increase the film forming speed, two or more dies may be provided on the metal support 31, and the dope amount may be divided to be stacked (sequential casting).

 [0179] The surface temperature of the metal support for casting is 10 to 55 ° C, the temperature of the dope is 25 to 60 ° C, and the temperature of the solution may be equal to or higher than the temperature of the support. It is more preferable to set the temperature to 5 ° C or more.

 [0180] The higher the solution temperature and the support temperature, the higher the drying speed of the solvent, which is preferable. However, if the temperature is too high, foaming or flatness may be deteriorated.

 [0181] The more preferred range of the temperature of the support depends on the organic solvent used, but 20-55. A more preferable range of C and the solution temperature is 35 to 45 ° C.

 [0182] (5) Solvent evaporation process

 Web (The name of the dope film after casting the dope on the metal support is the web.) 32 is heated on the metal support 31 and the solvent is evaporated until the web 32 can be peeled from the metal support 31. It is a process to make. To evaporate the solvent, there are a method of blowing wind from the web 32 side, a method of transferring heat with liquid from the back surface of Z or the metal support 31, and a method of transferring front and back forces by radiant heat. The backside liquid heat transfer method is preferred because of its good drying efficiency. A method of combining them is also preferable. In the case of backside liquid heat transfer, it is preferable to heat at or below the boiling point of the organic solvent having the lowest boiling point or the organic solvent having the lowest boiling point.

 [0183] (6) Peeling process

In this step, the web 32 having the solvent evaporated on the metal support 31 is peeled off at the peeling position 33. The peeled web 32 is sent to the next process. Residual melt of web 32 at the time of peeling If the amount of the medium (the formula described later) is too large, it will be difficult to peel off, or conversely, if it is peeled off after sufficiently drying on the metal support 31, a part of the web 32 will be peeled off. In the present invention, when the thin web is peeled off from the metal support, it is preferable to peel the thin web with a force within 170 NZm from the minimum tension that can be peeled as the peeling tension, in order to prevent the flatness from being deteriorated or twisted. A force of within is more preferred.

 [0184] There is a gel casting method (gel casting) as a method for increasing the film forming speed (the amount of residual solvent is as large as possible, and the film forming speed can be increased because of peeling). For example, a poor solvent for the cellulose ester is added to the dope and the gel is cast after casting the dope, and the gel is made by lowering the temperature of the metal support. By gelling on the metal support 31 and increasing the strength of the film at the time of peeling, peeling can be accelerated and the film forming speed can be increased. The web 32 on the metal support 31 can be peeled in the range of 5 to 150% by mass depending on the strength of the condition, the length of the metal support 31, etc., but peels off when the residual solvent amount is higher. In this case, if the web 32 is too soft, the flatness at the time of peeling will be lost, or vertical stripes will be generated due to the peeling tension, and the amount of residual solvent at the time of peeling will be determined by the balance between economic speed and quality. Therefore, in the present invention, the temperature at the peeling position on the metal support 31 is 10 to 40 ° C, preferably 15 to 30 ° C, and the residual solvent amount of the web 32 at the peeling position is 10 to 120. It is preferable to set it as the mass%.

 [0185] In order to maintain good flatness of the cellulose ester film during production, the amount of residual solvent when peeling from the metal support is preferably 10 to 150% by mass, more preferably 70. It is -150 mass%, More preferably, it is 100-130 mass%. The proportion of the good solvent contained in the residual solvent is preferably 50 to 90%, more preferably 60 to 90%, and particularly preferably 70 to 80%.

 [0186] In the present invention, the amount of residual solvent can be expressed by the following formula.

 [0187] Residual solvent amount (mass%) = {(M-N) / N} X 100

Here, M is a mass of the web at an arbitrary time point, and is a mass measured by the following gas chromatography. N is a mass when the M is dried at 110 ° C. for 3 hours. The measurement is performed by gas chromatography connected to a headspace sampler. In the present invention, gas chromatography 5890 SERISII manufactured by Hewlett-Packard Company and headspace support are used. The sampler HP7694 was used and the measurement was performed under the following conditions.

 [0188] Headspace sampler heating conditions: 120 ° C, 20 minutes

 GC introduction temperature: 150 ° C

 Temperature rise: 40 ° C, hold for 5 minutes → 100 ° C (8 ° CZ minutes)

 Column: DB & WAX manufactured by J & W (inner diameter 0.32mm, length 30m).

 [0189] (7) Drying process

After peeling, generally, the web 32 is dried using a roll drying device 35 that alternately conveys the web 32 through a plurality of rolls and a tenter device 34 that grips and conveys both ends of the web 32. In FIG. 6, the present invention is not limited only to the arrangement of the force in which the roll drying device 35 is arranged after the tenter device 34. As a means of drying, hot air is generally blown on both sides of the web, but there is also a means of heating by applying a microwave instead of the wind. Too rapid drying tends to impair the flatness of the finished film. The drying temperature is usually in the range of 40 to 250 ° C throughout. Depending on the solvent used, the drying temperature, amount of drying air, and drying time will differ, and the drying conditions should be selected appropriately according to the type and combination of solvents used. 37 is the winding of the finished cellulose ester film. In the drying process of a cellulose ester film, and more preferably wound in the residual solvent amount 0.5 wt _^0/0 to the following preferred instrument 0.1 wt% to below.

 [0190] The cellulose ester film of the present invention preferably has a free volume radius determined by the positron annihilation lifetime method of 0.250-0.310 nm. The method for measuring and controlling the free volume radius can be performed by the method described in Japanese Patent Application No. 2004-345733.

 [8191] (8) Stretching process (also called tenter process)

 The cellulose ester film of the present invention can exhibit birefringence by stretching. A film containing a solvent can be stretched during the production of the solution casting method, or a film in a state where the solvent is dried can be stretched. The stretching temperature is preferably a glass transition temperature of the film of 20 ° C. or lower and below the temperature at which it flows. Here, the glass transition temperature of the film can be measured by a known method. Stretching can be performed in the film forming direction or the width direction. In the present invention, it is preferable to stretch at least in the width direction.

[0192] By stretching, the cellulose ester resin exhibits birefringence and is acicular and birefringent. The ratio of the fine particles to be oriented increases in the stretching direction. The birefringence value of the cellulose ester film is considered to be the sum of the birefringence due to the cellulose ester resin and the birefringence due to the orientation of needle-shaped fine particles having birefringence. As a result, it has become possible to stably produce a cellulose ester film having characteristics that were conventionally difficult to produce.

 [0193] According to the present invention, the retardation value Ro was 105 nm ≤ Ro ≤ 350 nm, and Nz was 0.2 <Nz <0.7, more preferably Rth, which was difficult to produce with conventional cellulose ester films. However, it has become possible to stably produce cellulose ester films in the range of 30nm≤Rth≤ + 20nm. Moreover, the cellulose ester film of the present invention extends in the width direction by using fine particles having a needle shape and negative birefringence, but nevertheless, the direction orthogonal to the width direction, that is, the film forming direction. The film can have a slow axis. By using this cellulose ester film as a polarizing plate protective film, it is possible to provide a polarizing plate capable of suppressing light leakage at an oblique angle of 45 degrees and increasing the contrast, and in particular, in the transverse electric field switching mode. The viewing angle of the liquid crystal cell was greatly improved. The horizontal electric field switching mode here includes the power of the IPS mode and the fringe-field switching (FFS) mode, which can greatly improve the viewing angle as with the IPS mode.

 [0194] Ro, Rth, and Nz above are automatic birefringence meters KOBRA-21ADH (Oji Scientific Instruments)

 Measure the average refractive index of the sample with Abbe's refractometer in the same way, and perform a retardation measurement at a wavelength of 590 nm in an environment of 23 ° C and 55% RH. Was input to the following equation to obtain values of in-plane retardation Ro and thickness direction retardation Rth and Nz.

 [0195] Ro = (nx-ny) X d

 Rth = {(nx + ny) / 2-nz} X d

 Nz = (nx-nz) / (nx-ny) (where nx is the refractive index in the slow axis direction in the plane, ny is the refractive index in the direction perpendicular to the slow axis in the plane, and the thickness of the film) The refractive index in the direction is nz and d is the film thickness (nm).

The stretching process will be described in more detail. [0196] The preferred U and stretch ratio of the cellulose ester film of the present invention is 1.01 to 3 times, preferably 1.5 to 3 times, with respect to the film forming direction or the width direction. When stretching in the biaxial direction, the side to be stretched at high magnification is 1.01 to 3 times, preferably 1.5 to 3 times, and the stretching ratio in the other direction is 0.8 to 1.5. The film can be stretched by a factor of preferably 0.9 to 1.2.

 Thus, the cellulose ester film having the retardation value of the present invention can be preferably obtained, and a cellulose ester film having excellent flatness can be obtained. These width retention or transverse stretching in the film forming process is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

 [0198] An example of the stretching process (also referred to as the tenter process!) For producing the optical compensation film according to the present invention will be described with reference to FIG.

 [0199] In FIG. 2, step A is a step of gripping the film transported from a film transport step DO (not shown). In the next step B, the film is moved in the width direction (see FIG. 1). In the process C, the stretching is completed and the film is conveyed while being gripped.

 [0200] It is preferable to provide a slitter for cutting off the end in the film width direction after the film is peeled off and before the start of Step B and immediately after Z or Step C. In particular, it is preferable to provide a slitter that cuts off the film edge immediately before the start of the process A. When the same stretching in the width direction is performed, especially when the film edge is cut before the start of process B and the film edge is not cut. 条件 The former is more in the width direction of the film. An effect of improving the optical slow axis distribution (hereinafter referred to as the orientation angle distribution) can be obtained.

 [0201] This is considered to be an effect of suppressing unintentional stretching in the longitudinal direction from the peeling with a relatively large amount of residual solvent to the width stretching step B.

 [0202] In the tenter process, it is also preferable to intentionally create compartments having different temperatures in order to improve the orientation angle distribution. It is also preferable to provide a neutral zone between different temperature zones so that each zone does not interfere.

[0203] It is preferable to carry out the biaxial stretching in the casting direction and the width direction, which may be carried out in multiple stages. Simultaneous biaxial stretching is also used when biaxial stretching is performed. You may carry out in steps. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is performed in any one of the stages. It is also possible to bark. Simultaneous biaxial stretching also includes stretching in one direction and contracting the other while relaxing the tension.

 [0204] The stretching direction in the present invention is usually used to mean a direction in which a stretching stress is directly applied when performing a stretching operation, but in the case of biaxial stretching in multiple stages. In the end, it is used to mean the one with a larger draw ratio.

 [0205] It is well known that the orientation angle distribution deteriorates when the cellulose ester film is stretched in the width direction. There is a preferable film temperature relative relationship in steps A, B, and C in order to carry out lateral stretching with a constant ratio of Rth and Ro and a good orientation angle distribution. If the film temperatures at the end points of Steps A, B, and C are Ta ° C, Tb ° C, and Tc ° C, Ta≤Tb-10 is preferable. Moreover, it is preferable that Tc≤Tb. More preferably, Ta≤Tb 10 and Tc≤Tb.

 [0206] The film heating rate in step B is preferably in the range of 0.5 to 10 ° C Zs in order to improve the orientation angle distribution.

 [0207] The stretching time in Step B is preferably a short time in order to reduce the dimensional change rate under the conditions of 80 ° C and 90% RH. However, the minimum required stretching time range is defined from the viewpoint of film uniformity. Specifically, it is preferably in the range of 1 to 10 seconds, and more preferably 4 to 10 seconds. The temperature in step B is 40 to 180 ° C, preferably 100 to 160 ° C.

[0208] During the tenter process, the heat transfer coefficient may be constant or varied. The heat transfer coefficient preferably has a heat transfer coefficient in the range of 41.9 to 419 X 10 ³ jZm ² hr. More preferably, it is in the range of 41.9 to 209.5 X 10 ³ j / m ² hr, and the range of 41.9 to 126 X 10 ³ j / mr is most preferable.

[0209] In order to improve the dimensional stability under the conditions of 80 ° C and 90% RH, the stretching speed in the width direction in Step B may be constant or may be changed. The stretching speed is preferably 50 to 500% / min, more preferably 100 to 400% / min, and most preferably 200 to 300% Zmin. [0210] The ability to reduce the temperature distribution in the width direction of the atmosphere in the tenter process Ability to improve the uniformity of the film The temperature distribution in the width direction in the preferred tenter process is preferably within ± 5 ° C. Within ± 2 ° C is more preferable. Within ± 1 ° C is most preferable. By reducing the temperature distribution, it can be expected that the temperature distribution in the width of the film will also be reduced.

[0211] In step C, it is preferable to relax in the width direction in order to suppress dimensional changes. Specifically, it is preferable to adjust the film width to be in the range of 95 to 99.5% with respect to the film width of the previous step.

 [0212] After the treatment in the tenter process, it is preferable to further provide a post-drying process (hereinafter, process D1)! The power to perform at 50-160 ° C S Preferred ヽ. More preferably, it is in the range of 80 to 150 ° C, and most preferably in the range of 110 to 150 ° C.

 [0213] In Step D1, the fact that the atmospheric temperature distribution in the width direction of the film is small is also preferable from the viewpoint of enhancing the uniformity of the film. Within ± 5 ° C is preferred. Within ± 2 ° C is more preferred. Within ± 1 ° C is most preferred.

 [0214] The film transport tension in Step D1 is affected by the physical properties of the dope, at the time of peeling, the amount of residual solvent in Step DO, the temperature in Step D1, etc., but 120 to 200 N / m is preferred 140 -2 OONZm is more preferred. 140 to 160 NZm is most preferred.

 [0215] For the purpose of preventing the film from stretching in the transport direction in step D1, it is preferable to provide a tension cut roll. After drying, it is preferable to provide a slitter and cut off the end portion before winding to obtain a good shape.

 [0216] In the present invention, when the cellulose ester film is long, it is preferably coincident with the slow axial force conveying direction of the cellulose ester film. This is because a slow axis can be formed in the transport direction by continuously stretching a cellulose ester film containing needle-like negative birefringent fine particles in the width direction. The long PVA polarizer has an absorption axis in the longitudinal direction, and the slow axis of the cellulose ester film applied as a polarizing plate protective film is in the longitudinal direction. Become. This is a preferable configuration from the viewpoint of productivity of the polarizing plate.

[0217] (9) Winding process This is a step of winding the web after drying as a film. When the amount of residual solvent to finish drying is 0.5% by mass or less, preferably 0.1% by mass or less, a film having good dimensional stability can be obtained. Winding methods include tension control methods such as the constant torque method, constant tension method, taper tension method, and program tension control method with constant internal stress. You can use them properly.

[0218] The amount of residual solvent can be expressed by the following formula.

[0219] Residual solvent amount (% by mass) = {(M-N) / N} X 100

 Here, M is the mass of the web at any point, and N is the mass when M is dried at 110 ° C for 3 hours.

 [0220] The film thickness of the cellulose ester film varies depending on the purpose of use. From the viewpoint of reducing the thickness of the liquid crystal display device, the finished film is preferably in the range of 10 to 150 / ζ πι. 30 to the range of LOO μm In particular, the range of 40 to 80 μm is preferable. If it is too thin, for example, the required strength as a protective film for a polarizing plate may not be obtained. If it is too thick, the superiority of the thin film over the conventional cellulose ester film is lost. To adjust the film thickness, it is better to control the dope concentration, pumping amount, slit gap in the die base, die extrusion pressure, metal support speed, etc. to achieve the desired thickness. . Further, as a means for making the film thickness uniform, it is preferable to use a film thickness detection means to feed back the feedback information that has been programmed to each of the above-mentioned devices for adjustment.

 [0221] In the process up to the drying of the force immediately after casting through the solution casting film-forming method, the atmosphere in the drying apparatus may be air, but is performed in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. May be. However, the danger of the explosion limit of the evaporating solvent in a dry atmosphere must always be considered!

[0222] Next, a case where the cellulose ester film of the present invention is used in a lateral electric field switching mode type liquid crystal display device will be described. Here, the cellulose ester film of the present invention is referred to as a cellulose ester film A. In the present invention, the cellulose ester film A is used as a cellulose ester film disposed on the liquid crystal display cell side of a polarizing plate used in a liquid crystal panel of a transverse electric field switching mode type. The refractive index in the slow axis direction in the film plane is nx, the refractive index in the direction perpendicular to X in the film plane is ny, the refractive index in the film thickness direction is nz, and the film thickness is d (nm). Sometimes, the relation value Ro satisfying the relationship of nx>nz> ny and the following expression (i) Ro is 105 nm ≦ Ro ≦ 350 nm, and the Nz expressed by the following expression (ii) is 0.2. It is preferable to satisfy an optical value of <Nz <0.7. In particular, it is preferable that the direction of nx (the direction of the in-plane slow axis) is in the direction of film formation of cellulose ester film A.

[0223] Formula (i) Ro = (nx-ny) X d

 Formula (ii) Nz = ι, ηχ—nz) / (ηχ—ny)

 Formula (m) Rth = {(nx + ny) / 2-nz} X d

 The polarizing plate of the present invention uses the optical film as a protective film for the polarizing plate, and is disposed so that the slow axis of the optical film is substantially parallel or perpendicular to the absorption axis of the polarizer. Preferred.

 [0224] Further, one polarizing plate sandwiching the liquid crystal cell of the transverse electric field switching mode type is the polarizing plate, and the polarizing plate protective film disposed on the liquid crystal display cell side of the other polarizing plate — 15nm≤Ro It is particularly preferable because a lateral electric field switching mode type liquid crystal display device with improved viewing angle characteristics can be obtained when optical values of ≤15 nm and -15 nm≤Rth≤15 nm are satisfied.

 [0225] (Birefringence test method for fine particles showing acicular and birefringence)

 Cellulose ester and fine particles showing needle-like birefringence are dispersed in a solvent, cast into a film, and then dried by heating. The film having a transmittance of 80% or more is evaluated for birefringence.

[0226] The Abbe refractometer 1T was used to measure the refractive index using a multi-wavelength light source, and ny in the stretching direction and the refractive index in the in-plane direction perpendicular to each other were defined as nx. For a film where (ny−nx)> 0 for each refractive index at 550 nm, it is determined that the needle-like fine particles exhibiting birefringence are positively birefringent with respect to the stretching direction.

 [0227] The physical properties of the cellulose ester film and cellulose ester film A according to the present invention are summarized below.

[0228] (Transmittance of cellulose ester film)

500 nm transmittance of the cellulose ester film of the present invention is preferably 85 to 100% strength 90-: L00% strength is more preferable, and 92-: LOO% is most preferable. 400nm transmittance is 40 ~

100% force S preferred, 50-100% more preferred 60-100% most preferred. In addition, UV absorption performance may be required, and in that case, the transmittance at 380 nm is preferably 0 to 10%, more preferably 0 to 5%, and most preferably 0 to 3%.

[0229] (Thickness distribution in the width direction of cellulose ester film)

 The cellulose ester film of the present invention has a thickness distribution R (%) in the width direction of 0≤R (

%) ≤ 5% is preferred, more preferably 0≤R (%) ≤3%, particularly preferably 0≤R (%) ≤1%.

[0230] (Haze value of cellulose ester film)

 The cellulose ester film of the present invention has a haze value of preferably 2% or less, more preferably 1.5%, and most preferably 1% or less.

[0231] (Elastic modulus of cellulose ester film)

 The elastic modulus is preferably in the range of 1.5 to 5 GPa, more preferably in the range of 1.8 to 4 GPa, and particularly preferably in the range of 1.9 to 3 GPa.

[0232] The stress at break is preferably in the range of 50 to 200 MPa, more preferably in the range of 70 to 150 MPa, and most preferably in the range of 80 to: LOOMPa.

[0233] The elongation at break at 23 ° C and 55% RH is preferably in the range of 20-80% 30-6

The range of 0% is more preferable. The range of 40-50% is most preferable.

[0234] The hygroscopic expansion coefficient is preferably in the range of 1 to 1%. The range of 0.5 to 0.5% is preferable. The force S is more preferably 0 to 0.2% or less.

[0235] Further, in the range foreign matter bright spots is 0-80 amino ZCM ² ranges der Rukoto desirability instrument 0-60 amino ZCM ² It is further preferred instrument 0-30 pieces / cm ² Most preferred.

[0236] In general, when a cellulose ester film is used as a polarizing plate protective film, an alkali treatment is performed in order to improve the adhesion to the polarizer. Since the film after the alkali gel treatment and the polarizer are bonded using a polyvinyl alcohol aqueous solution as an adhesive, if the contact angle between the cellulose ester film and the water after the alkali hatching treatment is high, the film cannot be bonded with polyvinyl alcohol. It becomes a problem as a polarizing plate protective film.

[0237] For this reason, the contact angle of the cellulose ester film after the alkali hatching treatment is 0 to 60 °. 5 to 55 ° is preferable, and 10 to 30 ° is more preferable.

[0238] (Center line average roughness (Ra) of cellulose ester film)

 When a cellulose ester film is used as an LCD member, it is desirable that the flatness is high in order to reduce light leakage of the film. The centerline average roughness (Ra) is a numerical value defined in JIS B 0601, and examples of the measuring method include a stylus method or an optical method.

 [0239] The center line average roughness (Ra) of the cellulose ester film of the present invention is preferably 20 nm or less, more preferably lOnm or less, and particularly preferably 4 nm or less.

 [0240] (Polarizing plate)

 The polarizing plate of the present invention and the liquid crystal display device of the present invention using the polarizing plate will be described.

[0241] The polarizing plate can be produced by a general method. The cellulose ester film of the present invention that has been treated with an alkali acid solution uses a complete acid-polyvinyl alcohol aqueous solution on at least one surface of a polarizer produced by immersing and stretching a polybulal alcohol film in an iodine solution. It is preferable to stick them together. The cellulose ester film of the present invention may be used on the other surface, or another polarizing plate protective film may be used. A commercially available cellulose ester film can be used as the polarizing plate protective film used on the other side of the cellulose ester film of the present invention. For example, KC8UX2M, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC8UY—HA, KC8UX—RHA (manufactured by Co-Caminoltop Co., Ltd.) and the like are preferably used as commercially available cellulose ester films. In addition, the polarizing plate protective film used on the other side is provided with surface treatments such as an antireflection layer, an antiglare layer, an antistatic layer, an antifouling layer, and a hard coat layer. In other words, JP 2005-15507, JP 2004-151642, JP 20 03-121620, Japanese Patent Application 2004-126469, Japanese Patent Application 2004-111885, Japanese Patent Application 2003-391912, JP 2002-322558. A polarizing plate protective film that has been surface-treated by a method such as JP-A-2003-25504, JP-A-2003-121602, or JP-A-2003-177207 is preferably used. Alternatively, a film other than cellulose ester film such as cyclic olefin resin, acrylic resin, polyester, and polycarbonate may be used as the polarizing plate protective film on the other surface. In this case, since the suitability for Ken is low, the polarizing plate is inserted through an appropriate adhesive layer. I prefer to have an adhesive strength.

[0242] The polarizing plate of the present invention is obtained by using the cellulose ester film of the present invention on at least one side of a polarizer as a polarizing plate protective film. In this case, it is preferable that the slow axis of the cellulose ester film is arranged so as to be substantially parallel or perpendicular to the absorption axis of the polarizer! /.

 [0243] The cellulose ester film of the present invention (particularly preferably the above-mentioned cellulose ester film A) is a liquid crystal as one polarizing plate disposed across a liquid crystal cell of a transverse electric field switching mode type. It is preferable to place it on the display cell side! /.

 [0244] Examples of the polarizer preferably used in the polarizing plate of the present invention include a polyvinyl alcohol-based polarizing film, which is a polybutyl alcohol-based film dyed with iodine and a dichroic dye. There is something. As the polybula alcohol film, a modified polybulal alcohol film modified with ethylene is preferably used. As the polarizer, there is used a force for uniaxially stretching a polybulualcohol film, dyeing it uniaxially after dyeing, and preferably performing a durability treatment with a boron compound. The film thickness of the polarizer is 5 to 40 μm, preferably 5 to 30 μm, and particularly preferably 5 to 20 μm. A polarizing plate is formed by laminating one side of the cellulose ester film of the present invention on the surface of the polarizer. Preferably, it is bonded with a water-based adhesive mainly composed of complete poly-vinyl alcohol or the like. Further, in the case of a resin film other than the cellulose ester film, it can be bonded to the polarizing plate through an appropriate adhesive layer.

[0245] Since the polarizer is stretched in a uniaxial direction (usually the longitudinal direction), when the polarizing plate is placed in a high temperature and high humidity environment, the stretching direction (usually the longitudinal direction) shrinks and is orthogonal to the stretching. Extends in the direction (usually the width direction). As the thickness of the polarizing plate protective film becomes thinner, the rate of stretching of the polarizing plate increases, and in particular, the amount of contraction in the stretching direction of the polarizer increases. Usually, the direction of stretching of the polarizer is bonded to the casting direction (MD direction) of the polarizing plate protective film. Therefore, when the polarizing plate protective film is used as a thin film, it is particularly important to suppress the stretching rate in the casting direction. is there. Since the cellulose ester film of the present invention is excellent in dimensional stability, it is suitably used as such a polarizing plate protective film. [0246] The polarizing plate can be constituted by further bonding a protective film on one surface of the polarizing plate and a separate film on the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection.

[0247] (Horizontal electric field switching mode type liquid crystal display device)

 By incorporating the polarizing plate of the present invention into a commercially available transverse electric field switching mode liquid crystal display device, the liquid crystal display device of the present invention having excellent visibility and an increased viewing angle can be produced.

 [0248] The transverse electric field switching mode of the present invention is fringe electric field switching (FFS: Fringe).

 -Field Switching) mode is also included in the present invention, and the polarizing plate of the present invention can be incorporated similarly to the IPS mode, and the liquid crystal display device of the present invention having the same effect can be manufactured.

[0249] In the horizontal electric field switching mode type liquid crystal display device, polarizing plates are arranged on both sides of the driving liquid crystal cell. In the present invention, the cellulose ester film of the present invention (cellulose ester film A) satisfying the optical values of the retardation value Ro of 105 nm≤Ro≤350 nm and Nz of 0.2 <Nz <0.7 is polarizing plate protection. A polarizing plate A used as a film is used on one surface of the liquid crystal cell. At this time, the cellulose ester film A is disposed between the adjacent polarizer and the driving liquid crystal cell. Polarizing plate B placed on the other side across the liquid crystal cell uses optical film B that satisfies the optical values of -15 nm ≤ Ro ≤ 15 nm and 15 nm ≤ Rth ≤ 15 nm as the polarizing plate protective film. The optical film B is particularly preferably disposed between the adjacent polarizer and the driving liquid crystal cell. Specifically, although it is the configuration 1 in FIG. 3, the configuration may be such that the viewing side polarizing plate and the knock light side polarizing plate are arranged oppositely across the liquid crystal cell. Further, the arrangement of the cellulose ester film having the axis direction shown in FIG. 4, the polarizing plate, and the liquid crystal cell is preferred for the present invention, and can be cited as a lateral electric field switching mode type liquid crystal display device. That is, it is preferable that the polarizing plate protective film 2a of the configuration 1 in FIG. 3 is the cellulose ester film A and the polarizing plate protective film 2b is the optical film B or the polarizing plate protective film of the configuration 1 in FIG. It is preferable that 2a is an optical film—B and a polarizing plate protective film 2b is a cell mouth ester film A! /. [0250] In order to produce a film satisfying the above range of retardation values, the optical film B is preferably a cellulose ester film. This cellulose ester film B is described in JP-A-2003-12859. Can be produced by a method. Specifically, the adjustment of the retardation value in which it is preferable that the polymer described in paragraph Nos. [0032 to [0049] of JP-A-2003-12859 is contained in the cellulose ester film is performed. Can be done in different types and quantities.

[0251] These polymers have preferably a on that it is contained preferably instrument particularly 3 to 25% by weight of 1 to 35 mass _^0/0 contained in the cellulose ester film B controls the Rita one Deshiyon value.

 [0252] The cellulose ester film B can be produced by a known method for producing a cellulose ester film. In particular, it is preferable to produce it in combination with the above-mentioned additives which may use the production method described in JP-A-2002-249599.

 Example

 [0253] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “%” in the examples represents “mass%”.

[0254] Example 1

 (Production of cellulose ester film 1)

 (Preparation of dope 1)

 <Preparation of fine particle liquid 1>

 SrCO fine particles were prepared by the following method.

 Three

[0255] against water 375g [This, urea 81. 75 g (water [this against 21.8 mass _^0/0) were added strontium 30. 75 g (2 wt% 8. in water). Further reaction (20 mass _^0/0 in water) 75. 200 g of ethylene glycol as organic solvent to the reaction solution to perform below the freezing point was added. This solution was put into a reaction vessel, stirred and cooled while being irradiated with ultrasonic waves.

[0256] Shinto Kagaku Co., Ltd., three-one motor BLh600 as an agitator motor, Honda Electronics Co., Ltd., ultrasonic bath W-113MK II as a water bath with ultrasonic irradiation function, Thomas Scientific Instruments Co., Ltd. as a cooler A closed tank type handy cooler TRL-C13 was used. [0257] By circulating an ethylene glycol antifreeze (Thomas Scientific Instruments Co., Ltd., Nybrine (registered trademark)) in the water bath with a cooler, the temperature of the reaction solution was lowered to -5 ° C, and -5 ° C. Kept at C. Subsequently, 1.50 g of digestive enzyme Urease was added to the reaction solution. After the digestive enzyme was added, crystals started to precipitate in the reaction solution and became cloudy. The reaction was continued for 12 hours while maintaining the temperature of the reaction solution at 5 ° C.

[0258] Thereafter, the temperature of the reaction solution was raised to 20 ° C, and the crystals were aged for 12 hours while maintaining the temperature at 20 ° C. The obtained crystal was taken out by filtration and dried. The dried crystals were observed with a scanning electron microscope (SEM) and found to be strontium carbonate needle crystal particles having a needle ratio of 4 to 20 with a length of 500 nm or less (average 400 nm) and a thickness of 20 to 50 nm. Was confirmed.

[0259] The following composition was dispersed with an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.) at an output scale of 10 for 5 minutes continuously, and then dispersed with Ultraapex Mill UAMO 15 (Koto Kogyo Co., Ltd.) under the following conditions. A fine particle liquid 1 was prepared.

[0260] Strontium carbonate needle crystal particles prepared above 32g

 184 g of methylene chloride

 Ethanol 184g

 Dispersion media Zircon beads (particle size 50 m) 400 g J speed ”10 m / sec

 The circulation rate of the dispersion was circulated at 60mlZmin for 5 hours, and the mill jacket was cooled with cooling water.

 [0261] <Preparation of fine particle dispersion 1>

 Cellulose acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propional substitution degree 0.75, weight average molecular weight 190,000) 24.9 parts by mass

 Triphenyl phosphate 16 parts by mass

 Ethyl phthalyl tildaricolate 4 parts by mass

Tinuvin 326 (Ciba Specialty Chemicals) 0.6 parts by mass Tinuvin 109 (Ciba Specialty Chemicals) 1. 02 parts by mass Tinuvin 171 (Ciba Specialty Chemicals) 1.02 parts by mass Methylene chloride 499. 5 parts by mass Ethanol 57.5 parts by mass

 The composition was put into a container and completely dissolved.

[0262] While stirring this solution, 152.2 parts by mass of the fine particle liquid 1 was slowly added, and then 350 g of this mixed liquid was placed in a container with an output scale of 10 using an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.). A fine particle dispersion 1 was prepared by redispersing continuously for 10 minutes while cooling around the substrate with cold water.

 [0263] Fine particle dispersion 1 752. 9 parts by mass

 Cellulose acetate propionate (acetyl substitution degree 1.90, propionol substitution degree

(0.75) 149.6 parts by mass

 100 parts by mass of methylene chloride

 While thoroughly stirring the fine particle dispersion 1, cellulose acetate propionate and methylene chloride were slowly added and completely dissolved to obtain a dope 1.

[0264] <Production of cellulose ester film 1>

 The dope 1 was kept at 40 ° C. and uniformly cast on a stainless steel belt kept at 40 ° C. After the residual solvent amount was dried to 80%, it was peeled off from the stainless steel belt with a tension of 170 NZm. Then, both ends were gripped with a tenter and stretched by 1.4 times in the width direction (TD direction). Furthermore, it was dried at 120 ° C for 10 minutes while being transported with a number of rolls at a transport tension of 130 NZm, to obtain cellulose ester film 1 having a width of 80 m and a width of 1.3 m. Both ends were provided with a knurling with a height of 10 111 and a width of 1.5 cm.

[Preparation of cellulose ester film 2]

 Cellulose ester film 2 was obtained in the same manner as in the preparation of cellulose ester film 1 except that the draw ratio was 1.05 times.

[Preparation of cellulose ester film 3]

 (Preparation of dope 2)

 The fine particle solution 1 was prepared in the same manner as the fine particle solution 1 prepared when the dope 1 was prepared.

<Preparation of fine particle dispersion 2>

Cellulose acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propionyl substitution degree 0.75, weight average molecular weight 190,000) 8.7 parts by mass Triphenylenophosphate

 Ethyl phthalyl tildaricolate

 Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0. 60 parts Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1. 02 parts Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1. 02 parts Methylene chloride

 Ethanore

 The composition was put into a container and completely dissolved.

[0268] While stirring this solution, 152.2 parts by mass of the fine particle liquid 1 was slowly added, and then 350 g of this mixed liquid was mixed with an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.) at an output scale of 10. Redispersion was performed continuously for 10 minutes while cooling the surroundings with cold water.

<Preparation of dope stock solution>

 Cellulose acetate propionate (acetyl substitution degree 1.90, propionol substitution degree

0.75) 165.8 parts by weight

 Methylene chloride 449.9 parts by mass

 Ethanol 42.6 parts by mass

 The composition was put into a container and completely dissolved. While this solution was stirred, 341.7 parts by mass of the fine particle dispersion 2 was mixed to obtain Dope 2.

[0270] Using the dope 2, a cell mouth ester film 3 was produced in the same manner as in the production of the cellulose ester film 1.

[Preparation of cellulose ester film 4]

 Cellulose ester film 4 was obtained in the same manner as in the preparation of cellulose ester film 3 except that the draw ratio was 1.05 times.

[Preparation of cellulose ester film 5]

 (Preparation of dope 3)

 The fine particle solution 1 was prepared in the same manner as the fine particle solution 1 prepared when the dope 1 was prepared.

[0273] Cellulose acetate propionate (acetyl substitution degree 1.90, propional substitution degree 0.75) 174.5 parts by mass Triphenyl phosphate 16 parts by mass Ethyl phthalyl ethyl dallicolate 4 parts by mass

 Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.60 parts by mass Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1. 02 parts by mass Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1.02 parts by mass Methylene chloride 660. 4 parts by mass

 Ethanol 118.4 parts by mass

 The composition was put into a container and completely dissolved. While this solution was stirred, 7.6 parts by mass of the fine particle liquid 1 was slowly added and mixed to obtain a dope 3.

[0274] Cellulose ester film 5 was produced using this dope 3 in the same manner as in production of cellulose ester film 1.

[0275] Since this cellulose ester film has a small content of fine particles having needle-like birefringence, the dispersion state of the fine particles is almost the same, but the retardation value is not much different from a cellulose acetate film containing no fine particles. Stability and dispersion of phase difference values were also bad.

[Preparation of cellulose ester film 6]

 Cellulose ester film 6 was obtained in the same manner as in the preparation of cellulose ester film 5 except that the draw ratio was 1.05 times.

[0277] This cellulose ester film had the same results as the cellulose ester film 5.

 [Preparation of cellulose ester film 7]

 (Preparation of dope 4)

 <Preparation of fine particle liquid 2>

 Rutile-type titanium oxide TTO— S— 3 (particle diameter minor axis 10-20nm, major axis 50-: L00nm, needle ratio 2.5-10, manufactured by Ishihara Sangyo Co., Ltd.) 32g

 Ethanol 184g

 184 g of methylene chloride

Disperse the above composition with an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.) at an output scale of 10 for 5 minutes continuously, then with Ultrapax Mill UAM015 (Koto Kogyo Co., Ltd.) The dispersion was carried out.

 Dispersion volume 400g

 Dispersion media 50 m Zircon beads 400 g

 J "speed 10m / sec

 Circulating at a circulation rate of 60mlZmin for 5 hours, cooling the mill jacket with cooling water

<Preparation of fine particle dispersion 3>

 Cellulose acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propional substitution degree 0.75, weight average molecular weight 190,000) 24.9 parts by mass

 Triphenylenophosphate

 Ethyl phthalyl tildaricolate

 Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0. 60 parts Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1. 02 parts Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1. 02 parts Methylene chloride

 Ethanore

 The composition was put into a container and completely dissolved.

 [0281] While stirring this solution, 152.2 parts by mass of the fine particle liquid 2 was slowly added, and 350 g of this mixed liquid was added to the container with an output scale of 10 using an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.). Redispersion was performed continuously for 10 minutes while cooling the surroundings with cold water.

 [0282] Fine particle dispersion 3 752. 9 parts by mass

 Cellulose acetate propionate (acetyl substitution degree 1.90, propionol substitution degree

(0.75) 149.6 parts by mass

 100 parts by mass of methylene chloride

 While thoroughly stirring the fine particle dispersion 3, cellulose acetate propionate and methylene chloride were slowly added and completely dissolved to obtain a dope 4.

[0283] Using the dope 4, a cell mouth ester film 7 was produced in the same manner as the cellulose ester film 1. [Preparation of cellulose ester film 8]

 Cellulose ester film 8 was obtained in the same manner as in the preparation of cellulose ester film 7 except that the draw ratio was 1.05 times.

[Preparation of cellulose ester film 9]

 (Preparation of dope 5)

 <Preparation of fine particle liquid 3>

 Rutile-type titanium oxide TTO— S— 3 (particle diameter minor axis 10-20nm, major axis 50-: L00nm, needle ratio 2.5-10, manufactured by Ishihara Sangyo Co., Ltd.) 32g

 Ethanol 184g

 184 g of methylene chloride

 The composition was dispersed with an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.) at an output scale of 10 for 5 minutes continuously, and then dispersed with a sand grinder having the following constitution.

[0286] Mill part inner diameter 120mm, Height 180mm

 Stirring disc diameter 80mm, 3 pieces are attached to the shaft at intervals of 20mm

 Dispersion media 0.4mm Zirco Your Beads 400g

 Disc rotation speed 1200rpm

 Dispersion volume 400g

 The mill was sealed and dispersed in a batch system for 5 hours, and the mill jacket was cooled with cooling water.

<Preparation of fine particle dispersion 4>

 Cellulose acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propional substitution degree 0.75, weight average molecular weight 190,000) 24.9 parts by mass

 Triphenyl phosphate 16 parts by mass

 Ethyl phthalyl tildaricolate 4 parts by mass

 Tinuvin 326 (Ciba Specialty Chemicals) 0.6 parts by mass Tinuvin 109 (Ciba Specialty Chemicals) 1. 02 parts by mass Tinuvin 171 (Ciba Specialty Chemicals) 1.02 parts by mass Methylene chloride 499. 5 parts by mass

Ethanol 57.5 parts by mass The composition was put into a container and completely dissolved.

 [0288] While stirring this solution, 152.2 parts by mass of the fine particle liquid 3 was slowly added, and then 350 g of this mixed liquid was mixed with an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.) at an output scale of 10. Redispersion was performed continuously for 10 minutes while cooling the surroundings with cold water.

 [0289] Fine particle dispersion 4 752. 9 parts by mass

 Cellulose acetate propionate (acetyl substitution degree 1.90, propionol substitution degree

(0.75) 149.6 parts by mass

 100 parts by mass of methylene chloride

 While stirring fine particle dispersion 4 well, cellulose acetate propionate and methylene chloride were slowly added and completely dissolved to obtain Dope 5.

[0290] Using this dope 5, a cellulose ester film 9 was produced in the same manner as in the production of the cellulose ester film 1.

[Preparation of cellulose ester film 10]

 Cellulose ester film 10 was obtained in the same manner as in the preparation of cellulose ester film 9 except that the draw ratio was 1.05 times.

[Preparation of cellulose ester film 11]

 (Preparation of dope 6)

 The fine particle liquid 2 was prepared in the same manner as the fine particle liquid 2 when the dope 4 was prepared.

<Preparation of fine particle dispersion 5>

 Cellulose acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propional substitution degree 0.75, weight average molecular weight 190,000) 24.9 parts by mass

 Triphenyl phosphate 16 parts by mass

 Ethyl phthalyl tildaricolate 4 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.60 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1.02 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1.02 parts by weight methylene Chloride 699.5 parts by mass

Ethanol 57.5 parts by mass The composition was put into a container and completely dissolved.

 [0294] While stirring this solution, 152.2 parts by mass of the fine particle liquid 2 was slowly added and stirred to obtain a fine particle dispersion 5.

[0295] Fine particle dispersion 5 752. 9 parts by mass

 Cellulose acetate propionate (acetyl substitution degree 1.90, propionol substitution degree

(0.75) 149.6 parts by mass

 100 parts by mass of methylene chloride

 While stirring fine particle dispersion 5 well, cellulose acetate propionate and methylene chloride were slowly added and completely dissolved to obtain Dope 6.

[0296] Using this dope, a cellulose ester film 11 was produced in the same manner as in the production of the cellulose ester film 1.

[Preparation of cellulose ester film 12]

 Cellulose ester film 12 was obtained in the same manner as in the preparation of cellulose ester film 11 except that the draw ratio was 1.05 times.

[Preparation of cellulose ester film 13]

 (Preparation of dope 7)

 The fine particle solution 1 was prepared in the same manner as the fine particle solution 1 during the dope 1 preparation.

<Preparation of fine particle dispersion 6>

 Cellulose acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propionyl substitution degree 0.75)

 Triphenylenophosphate

 Ethyl phthalyl tildaricolate

 Tinuvin 326 (Ciba Specialty Chemicals) 0. 60 parts Tinuvin 109 (Ciba Specialty Chemicals) 1. 02 Parts Tinuvin 171 (Ciba Specialty Chemicals) 1. 02 Parts Methylene chloride

 Ethanore

The composition was put into a container and completely dissolved. [0300] While stirring this solution, 152.2 parts by mass of the fine particle liquid 1 was slowly added and mixed to obtain a fine particle dispersion 6.

 [0301] The dope stock solution was prepared in the same manner as the dope stock solution used in the production of cellulose ester film 3.

 [0302] The dope stock solution was charged into a container and mixed with 341.7 parts by mass of the fine particle dispersion 6 to obtain a dope 7.

 [0303] Using this dope 7, a cell mouth ester film 13 was prepared in the same manner as the cellulose ester film 1.

[0304] [Production of cellulose ester film 14]

 Cellulose ester film 14 was obtained in the same manner as in the preparation of cellulose ester film 13 except that the draw ratio was 1.05 times.

[Preparation of cellulose ester film 15]

 (Preparation of dope 8)

 The fine particle solution 1 was prepared in the same manner as the fine particle solution 1 during the dope 1 preparation.

<Preparation of fine particle dispersion 12>

 Polymethyl methacrylate (weight average molecular weight = 8000, fine particle-dispersed resin)

 8.7 parts by mass

 Triphenylenophosphate

 Ethyl phthalyl tildaricolate

 Tinuvin 326 (Ciba Specialty Chemicals) 0. 60 parts Tinuvin 109 (Ciba Specialty Chemicals) 1. 02 parts Tinuvin 171 (Ciba Specialty Chemicals) 1. 02 parts Methylene chloride

 Ethanore

 The composition was put into a container and completely dissolved.

[0307] After 152.2 parts by mass of the fine particle liquid 1 was slowly added while stirring this solution, 350 g of this mixed liquid was mixed with an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.) at an output scale of 10. Redispersion was performed continuously for 10 minutes while cooling the surroundings with cold water. <Preparation of dope stock solution>

 Cellulose acetate propionate (acetyl substitution degree 1.90, propionol substitution degree

0.75) 165.8 parts by weight

 Methylene chloride 449.9 parts by mass

 Ethanol 42.6 parts by mass

 The composition was put into a container and completely dissolved. While this solution was stirred, 341.7 mass parts of the fine particle dispersion 12 was mixed to obtain Dope 8.

 Using this dope 8, cell mouth ester film 15 was produced in the same manner as in production of cellulose ester film 1.

 [0310] [Production of cellulose ester film 16]

 A fine particle dispersion 2 and a dope stock solution were prepared in the same manner as the fine particle dispersion 2 and the dope stock solution in the production of the cellulose ester film 3.

 [0311] Keep the dope stock solution at 40 ° C, and keep the dope stock solution 660 parts by mass and the fine particle dispersion 2 to 340 parts by mass. The dope obtained by thoroughly mixing in the above was cast uniformly on a stainless steel belt kept at 40 ° C. After the residual solvent amount was dried to 80%, it was peeled off from the stainless steel belt with a tension of 17 ONZm. After that, both ends were held with a tenter and stretched by 1.4 times in the width direction (TD direction). Further, it was dried at 120 ° C. for 10 minutes while being transported by a number of rolls at a transport tension of 130 NZm, to obtain a cellulose ester film 16 having a film thickness of 80 / ζ πι and a width of 1.3 m. Both ends were provided with knurling with a height of 10 / z m and a width of 1.5 cm. Before winding the film, a retardation measuring device was provided to measure the retardation of the film.

 [0312] This film had Ro = 270 nm and Rth = Onm. If the measurement result of phase difference of the film during continuous production is a predetermined value (Ro = 270 nm, Rth = Onm), the relational expression of fluctuation of fine particle content and phase difference that have been obtained in advance From the above, the flow rate of the fine particle dispersion 2 was adjusted to a predetermined value.

 [0313] [Production of cellulose ester film 17]

In the preparation of microparticle liquid 1, microparticle liquid 6 was prepared using 20 μm zirconia beads instead of 50 μm zirconia beads. At this time, separation of beads by Apex Mill Was not sufficiently performed, and beads were slightly mixed in the fine particle liquid.

 [0314] For the preparation of the fine particle dispersion 2, the fine particle dispersion 11 was prepared by replacing the fine particle liquid 1 with the fine particle liquid 6.

 [0315] The dope 13 was prepared by replacing the fine particle dispersion 2 with the fine particle dispersion 11 in the preparation of the dope 2.

 [0316] Using the dope 13, a cellulose ester film 17 was produced in the same manner as in the production of the cellulose ester film 1.

[0317] [Production of cellulose ester film 18]

 In the preparation of the microparticle liquid 3, the microparticle liquid 4 was prepared using 0.3 mm zircon beads instead of the 0.4 mm zircon beads.

[0318] In the preparation of the fine particle dispersion 4, a fine particle dispersion 7 was prepared by replacing the fine particle liquid 3 with the fine particle liquid 4.

 [0319] Dope 5 was prepared by replacing fine particle dispersion 4 with fine particle dispersion 7 in the preparation of dope 5.

 [0320] Using this dope 9, a cellulose ester film 18 was produced in the same manner as in the production of the cellulose ester film 1.

[0321] [Production of cellulose ester film 19]

 (Preparation of dope 10)

 <Preparation of fine particle liquid 5>

 SrCO fine particles same as used in fine particle dispersion 1 28. 8g

 Three

 Cellulose to acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propional substitution degree 0.75, weight average molecular weight 190,000) 3.2 g methylene chloride 184 g

 Ethanol 184g

 The composition was dispersed with an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.) at an output scale of 10 for 5 minutes continuously, and then dispersed with an Ultraapex mill UAM015 (Koto Kogyo Co., Ltd.) under the following conditions.

[0322] Dispersion amount 400g Dispersion media 50 m Zirco-Beads 400 g J "speed 10 m / sec

 The circulation rate of the dispersion was circulated at 60mlZmin for 5 hours, and the mill jacket was cooled with cooling water.

 <Preparation of fine particle dispersion 8>

 Cellulose toacetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propional substitution degree 0.75, weight average molecular weight 190,000) 8.7 parts by mass of triphenolate phosphate

 Ethyl phthalyl tildaricolate

 Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0. 60 parts Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1. 02 parts Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1. 02 parts Methylene chloride

 Ethanore

 The composition was put into a container and completely dissolved.

 [0324] Stirring this solution, slowly adding 169.1 parts by mass of the microparticle liquid 5, 350 g of this mixture was mixed with an ultrasonic disperser UH-300 (manufactured by SMT Co., Ltd.) at an output scale of 10 Redispersion was performed continuously for 10 minutes while cooling the surroundings with cold water.

 [0325] <Preparation of dope stock solution>

 Cellulose toacetate propionate (degree of acetyl substitution 1.90, degree of substitution propion 0.775) 165. 8 parts by weight

 Methylene chloride 449.9 parts by mass

 Ethanol 42.6 parts by mass

 The composition was put into a container and completely dissolved.

 [0326] While stirring the dope stock solution, 341.7 mass parts of the fine particle dispersion 8 was mixed to prepare Dope 10.

[0327] Using this dope 10, a cellulose ester film 19 was produced in the same manner as in the production of the cellulose ester film 1. [Preparation of cellulose ester film 20]

 (Preparation of dope 11)

 The fine particle solution 1 was prepared in the same manner as the fine particle solution 1 during the dope 1 preparation.

[0329] (Preparation of fine particle dispersion 9)

 In preparing the fine particle dispersion 2, cellulose acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propiole substitution degree 0.75, weight average molecular weight 190,000) was added to cellulose. A fine particle dispersion 9 was prepared in the same manner as the fine particle dispersion 2, except that it was changed to acetate propionate (acetyl substitution degree 1.40, propiol substitution degree 0.25, weight average molecular weight 190,000).

[0330] A dope 11 was prepared in the same manner except that the fine particle dispersion 2 used in the preparation of the cellulose ester film 3 was replaced with the fine particle dispersion 9, whereby a cellulose ester film 20 was produced.

[Preparation of cellulose ester film 21]

 (Preparation of dope 12)

 The fine particle solution 1 was prepared in the same manner as the fine particle solution 1 during the dope 1 preparation.

[0332] (Preparation of fine particle dispersion 10)

 In preparing the fine particle dispersion 2, cellulose acetate propionate (resin for fine particle dispersion, acetyl substitution degree 1.90, propiole substitution degree 0.75, weight average molecular weight 190,000) was added to cellulose. A fine particle dispersion 10 was obtained in the same manner except that it was replaced with diacetate (manufactured by Daicel Chemical Industries, Ltd., L50, weight average molecular weight 52,000).

[0333] A dope 12 was prepared in the same manner except that the fine particle dispersion 2 used in the preparation of the cellulose ester film 3 was replaced with the fine particle dispersion 10, whereby a cellulose ester film 21 was produced.

[Preparation of cellulose ester film a]

 (Preparation of dope a)

 The fine particle solution 1 was prepared in the same manner as the fine particle solution 1 during the dope 1 preparation.

[0335] Cellulose acetate propionate (acetyl substitution degree 1.90, propion substitution degree 0.75) 174.5 parts by mass Triphenolate phosphate 16 parts by weight Ethylphthalyl ethyldalicolate 4 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.60 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1. 02 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1.02 parts by weight Methylene chloride 599.5 parts by weight

 Ethanore 57.5 parts by mass

 The composition was put into a container and completely dissolved. While stirring this solution, 152.2 parts by mass of the fine particle liquid 1 was slowly added and mixed to obtain a dope a.

 [0336] Using this dope a, a cellulose ester film a was produced in the same manner as in the production of the cellulose ester film 1.

 [Preparation of cellulose ester film b]

 (Preparation of dope b)

 The fine particle solution 1 was prepared in the same manner as the fine particle solution 1 during the dope 1 preparation.

 [0338] Triphenylenophosphate

 Ethyl phthalyl tildaricolate

 Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0. 60 parts Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1. 02 parts Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1. 02 parts Methylene chloride

 Ethanore

 Particulate liquid 1

 The composition was put into a container and completely dissolved.

 [0339] While stirring this solution, cellulose acetate propionate (acetyl substitution degree 1.90, propional substitution degree 0.75) 174.5 parts by mass was slowly added and mixed to obtain dope b.

[0340] Using this dope b, a cellulose ester film b was produced in the same manner as in the production of the cellulose ester film 1. [Preparation of cellulose ester film c]

 (Preparation of dope c)

 Cellulose acetate propionate (acetyl substitution degree 1.90, propional substitution degree 0.75) 176.9 parts by weight

 Triphenyl phosphate 16 parts by mass

 Ethyl phthalyl tildaricolate 4 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.57 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 0.9 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 0.9 parts by weight Methylene Chloride 678.5 parts by weight

 Ethanore 129.

 The above composition was put into a container and completely dissolved and mixed to obtain a dope c.

 [0342] Using this dope, a cell mouth ester film c was produced in the same manner as in the production of the cell mouth ester film 1.

 [Evaluation of cellulose ester film]

 The following evaluation was performed on the produced cellulose ester film.

 [0344] (Evaluation of fine particle dispersibility)

 The produced cellulose ester film was photographed with a transmission electron microscope at a magnification of 100,000 times, and the image was observed and evaluated according to the following criteria.

 [0345] ○: The fine particles are uniformly dispersed in the primary particles

 Δ: Particles are slightly agglomerated!

 X: Fine particles are aggregated (hundreds)

 (Retrieval measurement of Ro and Rth)

The average refractive index of the optical film was measured using an Abbe refractometer 1T (manufactured by Atago Co., Ltd.) and a spectral light source device. Also, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) that measured the thickness of the film using a commercially available micrometer, it was left for 24 hours in an environment of 23 ° C and 55% RH. The film has a wavelength of 590 nm under the same environment. The film retardation measurement was performed. The above-mentioned average refractive index and film thickness were input into the following formula, and the values of in-plane retardation Ro and thickness direction retardation Rth were obtained.

[0347] Ro = (nx ny) X d

(1(式中、面内の遅相軸方向の屈折率を nx、面内で 遅相軸に直交する方向の屈折率を ny、フィルムの厚さ方向の屈折率を nz、 dはフィ ルムの厚み（nm)をそれぞれ表す。）

(1 (where nx is the refractive index in the slow axis direction in the plane, ny is the refractive index in the direction perpendicular to the slow axis in the plane, nz is the refractive index in the thickness direction of the film, and d is the film) Represents the thickness (nm) of each)

 (Evaluation of retardance stability)

 Rth measured at 23 ° C and 80% RH for 5 hours, then Rth measured in the same environment is defined as Rth (80% RH). Rth was Rth (20% RH), and the absolute value of the difference was the stability of the retardation. Retardation stability ARth = I Rth (80% RH) -Rth (20% RH) |

 (Evaluation of variation in retardance)

 5 points equally in the TD direction of the produced cellulose ester film, 4 rows on the winding core side in the lm direction in the MD direction, 20 points in total, and 4 rows in every lm in the middle of the winding. In addition, Ro was measured for 60 points in total, 20 points in 4 rows every lm on the outside of the winding. The variation of Ro measured in this way was calculated as follows.

[0348] Variation of Ro (%) = (Maximum value of Ro Minimum value of Ro) Average value of ZRo X 100

 (Haze value)

 According to JIS K-7136, a haze meter NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) was used as a transparency index.

[0349] Tables 1 and 2 show the obtained results.

[0350] [Table 1] [] ¾ [] 03512

W

[0352] From Tables 1 and 2, the cellulose ester film of the present invention can efficiently express the phase value as compared with the comparative example, and the variation in the phase difference value is small, and the stability is excellent. It turns out that it is a cellulose-ester film with little haze.

 [0353] Example 2

 [Preparation of polarizing plates 1 and 2]

A polybutal alcohol film having a thickness of 50 m was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). Immerse this in an aqueous solution that also has a specific power of 0.075 g of iodine, 6 g of potassium iodide, and lOOg of water, and then in an aqueous solution of 68 ° C that also has a specific power of 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. did. This was washed with water and dried to obtain a polarizer. Then, polarizing plates 1 and 2 were produced according to steps 1 to 5. [0354] (Process 1)

 As the polarizing plate protective film, the cellulose ester film 16 of the present invention prepared in Example 1 and the cellulose ester film a of the comparative example were immersed in a 2 mol ZL sodium hydroxide solution at 60 ° C for 90 seconds, and then washed with water. The side to be dried and bonded to the polarizer was acidified.

 [0355] Similarly, as a polarizing plate protective film on the opposite side, a commercially available cellulose ester film K C8UX2M (manufactured by Konica Minoltaput Co., Ltd.) was also hatched.

 [0356] (Process 2)

 The polarizer was immersed for 1 to 2 seconds in a polybulal alcohol adhesive bath having a solid content of 2%.

[0357] (Process 3)

 The excess adhesive adhering to the polarizer in Step 2 was gently wiped off, and this was placed on the oxidized surface of the cell mouth ester film 16 of the present invention treated in Step 1 and further the polarizing plate protective film on the opposite side As a polarizing plate 1, the commercially available cellulose ester film KC8 UX2M treated in step 1 was laminated so that the acidified surface was in contact with the polarizer.

 A polarizing plate 2 was obtained by laminating with a polarizer in the same manner except that the cellulose ester film 16 (present invention) was changed to a cellulose ester film a (comparative example).

 [0359] (Process 4)

In Step 3, the polarizing plate on which the cellulose ester film and the polarizer were laminated was bonded at a pressure of 20-30 N / cm ² and a conveying speed of about ² mZ.

[0360] (Process 5)

 The polarizing plate produced in Step 4 was dried for 2 minutes in a dryer at 80 ° C.

[Preparation of Polarizing Plate 3]

 The cellulose ester film B used for the polarizing plate 3 was produced as follows.

[0362] <Production of polymer>

Bulk polymerization was carried out by the polymerization method described in JP-A-2000-344823. That is, the contents were heated to 70 ° C. while introducing the following methyl metatalylate and ruthenocene into a flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, an inlet, and a reflux condenser. Next, half of the j8-mercaptopropionic acid sufficiently purged with nitrogen gas was added into the flask with stirring. After adding β-mercaptopropionic acid, bring the contents in the flask under stirring to 70 ° C The polymerization was carried out for 2 hours. Further addition of the remaining half of | 8-mercaptopropionic acid, which was purged with nitrogen gas, and then the polymerization was conducted for 4 hours while maintaining the temperature of the stirring content at 70 ° C. The temperature of the reaction product was returned to room temperature, and 20 parts by mass of a 5% benzoquinone tetrahydrofuran solution was added to the reaction product to terminate the polymerization. While gradually heating the polymer to 80 ° C. under reduced pressure with an evaporator, the tetrahydrofuran, residual monomer and residual thiol compound were removed to obtain a polymer. The weight average molecular weight was 3,400. The hydroxyl value (according to the measurement method below) was 50.

[0363] 100 parts by mass of methyl metatalylate

 Ruthenocene (metal catalyst) 0.05 parts by mass

 β Mercaptopropionic acid 12 parts by mass

 (Measurement method of hydroxyl value)

 This measurement conforms to JIS Κ 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bound to a hydroxyl group when sample lg is acetylated. Specifically, sample Xg (about lg) is precisely weighed in a flask, and 20 ml of acetylating reagent (20 ml of acetic anhydride with pyridine added to 400 ml) is accurately added to this. Attach an air condenser to the mouth of the flask and heat in a 95-100 ° C glycerin bath. After 1 hour and 30 minutes, cool and add 1 ml of purified water from the air cooling tube to decompose acetic anhydride into acetic acid. Next, titration is performed with a 0.5 mol ZL aqueous solution of potassium hydroxide and potassium ethanol using a potentiometric titrator, and the inflection point of the obtained titration curve is set as the end point. In addition, as a blank test, titrate without a sample, and obtain the inflection point of the titration curve. The hydroxyl value is calculated by the following formula:

[0364] Hydroxyl value = {(B— C) X f X 28. 05ZX} + D

 In the formula, B is the amount of 0.5 mol ZL of hydroxy- potassium carbonate solution used for the blank test (ml), C is the amount of 0.5 mol ZL of hydroxy-potassium potassium ethanol solution used for titration (ml), f is a factor of 0.5 mol ZL potassium hydroxide ethanol solution, D is acid value, and 28. 05 is 1Z2 of potassium hydroxide lmol amount 56.11.

<Preparation of cellulose ester film B used for polarizing plate 3>

(Silicon dioxide dispersion B) Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 16nm, apparent specific gravity 90gZ liter) 12 parts by mass

 88 parts by mass of ethanol

 The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. The liquid turbidity after dispersion was 200 ppm. 88 parts by mass of methylene chloride was added to the silicon dioxide dispersion with stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare silicon dioxide dispersion diluent B.

[0366] (Preparation of inline additive solution B)

 Tinuvin 109 (Ciba Specialty Chemicals Co., Ltd.) 11 parts by mass Tinuvin 171 (Ciba Specialty Chemicals Co., Ltd.) 5 parts by mass Methylene chloride 100 parts by mass

 The above was put into a sealed container, heated, stirred and completely dissolved and filtered.

[0367] To this, 36 parts by mass of silicon dioxide dispersion diluent B was added with stirring, and the mixture was further stirred for 30 minutes, and then cellulose acetate propionate (degree of substitution of acetyl group 1.9, degree of substitution of propiol group 0) 8) 6 parts by mass was added with stirring, and the mixture was further stirred for 60 minutes, followed by filtration with Advantech Toyo Co., Ltd. polypropylene wind cartridge filter TCW-PPS-1 N to prepare inline additive solution B.

[0368] (Preparation of dope solution B)

 Cellulose acetate (acetyl substitution degree 2.92, molecular weight Mn = 148000, molecular weight Mw = 310000, Mw / Mn = 2.1) 100 parts by mass

 12 parts by mass of the polymer prepared above

 440 parts by mass of methylene chloride

 40 parts by mass of ethanol

 The above was put into a sealed container, heated, stirred and completely dissolved, and filtered using Azumi filter paper No. 24 manufactured by Azumi Filter Paper Co., to prepare a dope solution B.

[0369] The dope solution B was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. in the film forming line. In-line additive solution B was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. in the in-line additive solution line. 100 parts by weight of filtered dope solution B and 2 parts of filtered inline additive solution B In addition, the in-line mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ) was mixed sufficiently, and then the belt was cast on a stainless steel band support at a temperature of 35 ° C and a width of 1.8 m. Cast uniformly. With the stainless steel band support, the solvent was evaporated until the residual solvent amount became 120%, and the force on the stainless steel band support was also released. Evaporate the solvent from the cellulose ester web at 35 ° C, slit it to a width of 1.65 m, and then stretch it 1.1 times in the TD direction (direction perpendicular to the film transport direction) with a tenter. And dried at a drying temperature of 150 ° C. At this time, the residual solvent amount when starting stretching with a tenter was 30%.

 [0370] After that, drying was completed while transporting the drying zone at 110 ° C and 120 ° C with many rolls, and slitting to a width of 1.5m, and a narling with a width of 15mm and an average height of 10m at both ends of the film. The cellulose acetate film B used for the polarizing plate 3 having a film thickness of 80 m was obtained by winding it around a 6-inch inner diameter with an initial tension of 220 NZm and a final tension of lONZm.

 [0371] When the retardation value of this cellulose ester film B was measured, it was found that Ro = 0.1 nm and Rth = Onm.

 [0372] A polarizing plate 3 was prepared in the same manner as in the production of the polarizing plate 1, except that the above cellulose ester film B was used in place of the cellulose ester film 16 of the present invention.

 [Evaluation of Polarizing Plate]

 The produced polarizing plates 1 and 2 were cut to prepare two polarizing plates. The transmittance at 550 nm was measured using a spectrophotometer U-3310 (manufactured by Hitachi, Ltd.) for a polarizing plate in which the same polarizing plate was orthogonal. The polarizing plate 1 using the cellulose ester film 16 of the present invention is 0.1%, the polarizing plate 2 using the cellulose ester film a as a comparative example is 0.5%, and the polarizing plate of the present invention is uniform. Because it is excellent, the light leakage of the orthogonal polarizing plate was small.

 [0374] Example 3

 [Production of liquid crystal display device]

 A liquid crystal panel for evaluating visibility was produced as follows.

[0375] Polarizing plates 1 and 2 produced in Example 2 above by peeling off the polarizing plates on both sides, which had been pasted together, using Hitachi LCD TV Wooo W17—LC50, which is an IPS mode liquid crystal display device Are bonded to the glass surface of the liquid crystal cell, and the above The polarizing plate 3 produced in Example 2 was bonded. At that time, the polarizing plate was prepared so that the slow axis of the cellulose ester film, the absorption axis of the polarizer, the direction of the slow axis of the liquid crystal cell, and the configuration of the liquid crystal display device were as shown in FIGS. At the same time, the LCD panel was attached.

 [Visibility evaluation of liquid crystal display device]

White and black were displayed on the liquid crystal panel produced above, and the luminance unevenness and light leakage at that time were visually evaluated. In the liquid crystal panel produced using the polarizing plate 1 using the cellulose ester film 16 of the present invention, there was almost no light leakage of black display with less luminance unevenness in white display. On the other hand, in the liquid crystal panel produced using the polarizing plate 2 using the cellulose ester film a as a comparative example, luminance unevenness in white display was conspicuous, and light leakage in black display was also observed. Further, when the liquid crystal panel was continuously lit for 24 hours and the panel temperature rose, the luminance unevenness and light leakage were also visually evaluated. As a result, the polarizing plate 1 using the cellulose ester film 16 of the present invention was used. The manufactured liquid crystal panel maintained the initial favorable state with no fluctuations in luminance unevenness and light leakage, but in the liquid crystal panel manufactured using the polarizing plate 2 using the cellulose ester film _a as _a comparative example, Luminance unevenness and light leakage were further deteriorated.

 [0377] With respect to the polarizing plate according to the example of the present invention, since there is little variation in phase difference, there is little initial luminance unevenness and light leakage, and there is excellent stability of phase difference. There was almost no deterioration.

Claims

The scope of the claims  [1] A method for producing a cellulose ester film containing needle-like fine particles having birefringence by a solution casting method, wherein a fine particle dispersion containing at least the fine particles and a resin for dispersing the fine particles is prepared in advance. A method for producing a cellulose ester film, comprising: preparing a dope by mixing the fine particle dispersion, a solvent, and a cellulose ester; and casting the dope in a solution.  [2] The production of the cellulose ester film according to claim 1, wherein a media distributor having a bead diameter of 0.03 to 0.3 mm is used when preparing the fine particle dispersion. Method.  [3] The method for producing a cellulose ester film according to [1] or [2], wherein the fine particle dispersion contains a cellulose ester.  [4] A method for producing a cellulose ester film in which needle-like fine particles having birefringence, a cellulose ester and a dope containing a solvent are cast on a support, and then dried! The dope has a step of stretching in any of the drying steps, has a step of measuring the birefringence of the stretched film, and is included in the dope depending on the result obtained in the step of measuring the birefringence. A method for producing a cellulose ester film, comprising adjusting the content of the fine particles.  [5] A cellulose ester film produced by the method for producing a cellulose ester film described in claim 1 or 4 in claims 1 to 4.  [6] A polarizing plate comprising the cellulose ester film according to claim 5 on at least one surface.  [7] A liquid crystal display device comprising the polarizing plate according to claim 6.