JP2007039524A - Alkali saponification method, cellulose acylate film, optical film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkali saponification method of a polymer film, by which method a cellulose ester film can be suitably subjected to an alkali saponification treatment in order to easily produce an optical film having a large area free from display defects in a liquid crystal display device; a cellulose acylate film produced by the above method; and an optical film, a polarizing plate, and a liquid crystal display device produced by using the cellulose acylate film. <P>SOLUTION: The alkali saponification method of a polymer film has a process for washing an alkali solution present on a polymer film by using water or an alkali washing liquid containing water and an organic solvent, the process for washing being conducted by using a roll coater or a rod coater. A cellulose acylate film produced by the method is provided, and an optical film, a polarizing plate, and a liquid crystal display device prepared by using the cellulose acylate film are also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for alkali saponification of a polymer film, a cellulose acylate film, an optical film, a polarizing plate and a liquid crystal display device. In particular, the present invention relates to a method for alkali saponification of a cellulose acylate film that is advantageously used as a transparent support for a long optical compensation sheet.

  The liquid crystal display device includes a liquid crystal cell, a polarizing plate, and an optical compensation sheet (retardation plate). In the transmissive liquid crystal display device, two polarizing plates are attached to both sides of the liquid crystal cell, and one or two optical compensation sheets are disposed between the liquid crystal cell and the polarizing plate. The reflection type liquid crystal display device includes a reflection plate, a liquid crystal cell, one optical compensation sheet, and one polarizing plate. The liquid crystal cell is composed of a rod-like liquid crystal molecule, two substrates for enclosing it, and an electrode layer for applying a voltage to the rod-like liquid crystal molecule, and the liquid crystal cell is different in the alignment state of the rod-like liquid crystal molecule, As for the transmission type, TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferro-electric Liquid Crystal), OCB (Optically Compensatory Bend), STN (Super Twisted Nematic), VA (Vertically Aligned), reflection type Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed. The polarizing plate generally comprises a polarizing plate and two transparent protective films provided on both sides of the polarizing plate. The deflection film is generally obtained by impregnating polyvinyl alcohol with an aqueous solution of iodine or a dichroic dye, and further uniaxially stretching the film.

  Optical compensation sheets are used in various liquid crystal display devices in order to eliminate image coloring and expand the viewing angle. As an optical compensation sheet, a stretched birefringent film has been conventionally used. It has been proposed to use an optical compensation sheet having an optically anisotropic layer formed of liquid crystalline molecules (particularly discotic liquid crystalline molecules) on a transparent support, instead of an optical compensation sheet made of a stretched birefringent film. ing. The optically anisotropic layer is formed by aligning liquid crystalline molecules and fixing the alignment state. In general, liquid crystal molecules having a polymerizable group are used to fix the alignment state by a polymerization reaction. Liquid crystalline molecules have a large birefringence. Furthermore, liquid crystal molecules have various alignment forms. By using liquid crystalline molecules in the optical compensation sheet, it has become possible to realize optical characteristics that could not be obtained with conventional stretched birefringent films.

  The optical properties of the optical compensation sheet are designed according to the optical properties of the liquid crystal cell, specifically, the difference in the display mode of the liquid crystal cell as described above. When a liquid crystal molecule, particularly a discotic liquid crystal molecule is used as the optical compensation sheet, an optical compensation sheet having various optical characteristics corresponding to various display modes of the liquid crystal cell can be produced. Optical compensation sheets using discotic liquid crystal molecules have been proposed that correspond to various display modes. Specifically, an optical compensation sheet for a TN mode liquid crystal cell (for example, see Patent Documents 1 to 3), an optical compensation sheet for an ECB mode liquid crystal cell (for example, see Patent Document 4), an IPS mode or FLC mode liquid crystal Cell optical compensation sheet (for example, see Patent Document 5), OCB mode or HAN mode liquid crystal cell optical compensation sheet (for example, see Patent Documents 6 and 7), STN mode liquid crystal cell optical compensation sheet (for example, Patent Document 8) and an optical compensation sheet for a VA mode liquid crystal cell (for example, see Patent Document 9) have been proposed.

If an elliptically polarizing plate is formed by laminating an optical compensation sheet using liquid crystalline molecules and a polarizing film, the optical compensation sheet can also function as one transparent protective film of the polarizing plate. Such an elliptically polarizing plate has a layer structure in which a transparent protective film, a polarizing film, a transparent support, and an optically anisotropic layer formed of liquid crystalline molecules are laminated in this order. Since liquid crystal display devices are required to have a thin and lightweight characteristic, if one of the components can be reduced by using both the transparent protective film of the polarizing plate and the optical compensation sheet, the device can be made thinner and lighter. It becomes possible to do. Further, by reducing the number of components of the liquid crystal display device, the number of steps for attaching the components is also reduced, and the possibility of failure or the like when assembling the apparatus is reduced. An integrated elliptical polarizing plate in which a transparent support of an optical compensation sheet using liquid crystalline molecules and one protective film of a polarizing plate are made common has been proposed specifically in Patent Documents 10 to 12, for example.
On the other hand, an alkali saponification method has been proposed as a technique for eliminating fine display unevenness due to thickness unevenness of a transparent support having a gelatin undercoat layer that has been used in the production of optical compensation sheets (Patent Document 13). .
In addition, Patent Documents 14 to 16 propose alkali saponification methods as techniques for improving the adhesion between the alignment film of the optical compensation sheet and the cellulose acylate film used as a transparent support. Further, Patent Document 17 proposes an alkali saponification method of a cellulose ester film for the purpose of improving display defects in a liquid crystal display device.
JP-A-6-214116 US Pat. No. 5,583,679 US Pat. No. 5,646,703 West German Patent Application No. 3911620 Japanese Patent Laid-Open No. 10-54982 US Pat. No. 5,805,253 International Publication No. 96/37804 Pamphlet JP-A-9-26572 Japanese Patent No. 2866372 Japanese Patent Laid-Open No. 7-191217 JP-A-8-21996 JP-A-8-94838 JP 2003-313326 A JP 2004-182858 A JP 2004-182893 A JP 2004-225002 A JP 2004-203965 A

In recent years, liquid crystal display devices have become increasingly high definition, high brightness, and large screen. Therefore, it has been found that streaks, unevenness, etc. of the transparent support of the optical compensation sheet, which could not be understood by conventional liquid crystal display devices, may be recognized as a failure of the optical compensation sheet.
Moreover, in the said prior art (patent documents 13 to 17), in order to remove the alkaline solution used for saponification, the method of spraying washing water was proposed. In this method, the cleaning water is sprayed with a fountain coater and the cleaning water is scraped off with an air knife, so that the cleaning water contaminated in this process may scatter and contaminate the surface opposite to the surface to be cleaned. I understand that. In addition, the washing water flows down on the polymer film to be cleaned, but its form can be visually recognized as a planar failure on the optical film using the saponified polymer film prepared by the conventional method and the polarizing plate processed with it. I have found that there is sex.

  An object of the present invention is to provide a method for alkali saponification of a polymer film that can be appropriately subjected to alkali saponification treatment in order to easily produce a large area optical film (optical compensation sheet) free from display defects in a liquid crystal display device. That is. Another object of the present invention is to provide a method for alkali saponification of a polymer film, which can saponify a polymer film that can be used as a transparent support of an optical compensation sheet by means that does not impair transparency and planarity. It is to be. Furthermore, an object of the present invention is to provide an alkali saponification method of a polymer film in which a polymer film used as a transparent support is alkali saponified so that the adhesion between the transparent support of the optical compensation sheet and the alignment film can be controlled with high accuracy. Is to provide. Still another object of the present invention is to provide a cellulose acylate film produced by the alkali saponification method, an optical film using the same, a polarizing plate and a liquid crystal display device.

By including an organic solvent in the alkaline solution used for the alkaline saponification, the saponification reaction activity can be increased as compared with a pure water solvent. However, depending on the type of the organic solvent, there is a defect that the optical properties of the polymer film are deteriorated, which causes a display failure when used in a liquid crystal display device. As a result of intensive studies to solve this problem, the present inventors have conducted a process of washing an alkaline solution present on a polymer film using an alkaline washing solution containing water or water and an organic solvent, which is performed after a saponification reaction. It has been found that by carrying out with a coater or a rod coater, the surface of the polymer film can be cleaned by alkali saponification without impairing the optical properties of the polymer film.
Further, the present inventors have found that the surface of the polymer film to be saponified can be saponified quickly without impairing optical properties by controlling the temperature of the coating surface of the polymer film to a predetermined temperature in advance and applying an alkaline solution. Furthermore, by controlling the temperature of the coating surface of the polymer film to be saponified to a predetermined temperature in advance and holding it at the predetermined temperature for a predetermined time after applying the alkaline solution, the polymer can be rapidly recovered without damaging the optical properties. It was found that the film surface can be saponified. Dilution of an alkaline solution with an appropriate diluent is considered to have the effect of forming a uniform mixed state at the interface between the alkaline solution and the diluent at the initial stage of film cleaning due to the appropriate liquid properties and suppressing the occurrence of failure there. It is done.
Furthermore, by adding a surfactant to the alkaline solution to be used, the surfactant in the alkaline solution significantly suppresses or eliminates elution of the polymer film-containing substance from the film, and the organic solvent contains the film. Even if the substance is eluted, it is considered that there is an effect such that it is stably present in the alkaline solution, and the extracted substance does not precipitate and solidify in the subsequent washing process. Found to improve.

That is, the subject of this invention is the alkali saponification method of following (1)-(15), the surface saponified cellulose-ester film of following (16), the optical film of following (17), the polarizing plate of following (18), and the following ( This is achieved by the liquid crystal display devices of 19) to (20).
(1) having a step of washing an alkaline solution present on the polymer film using an alkaline washing solution containing water or water and an organic solvent;
The method for alkali saponification of a polymer film, wherein the washing step is performed using a roll coater or a rod coater.
(2) A step of applying an alkaline solution to a polymer film having a temperature of room temperature or higher,
Washing the alkaline solution present on the polymer film with water or an alkaline washing liquid containing water and an organic solvent,
The method for alkali saponification of a polymer film, wherein the washing step is performed using a roll coater or a rod coater.
(3) A step of applying an alkaline solution to a polymer film having a temperature of room temperature or higher,
Maintaining the temperature of the polymer film above room temperature,
Washing the alkaline solution present on the polymer film with water or an alkaline washing liquid containing water and an organic solvent,
The method for alkali saponification of a polymer film, wherein the washing step is performed using a roll coater or a rod coater.
(4) A step of heating the polymer film above room temperature in advance,
Applying an alkaline solution to the polymer film;
Maintaining the temperature of the polymer film above room temperature,
Washing the alkaline solution present on the polymer film with water or an alkaline washing liquid containing water and an organic solvent,
The method for alkali saponification of a polymer film, wherein the washing step is performed using a roll coater or a rod coater.
(5) [1] The reapplying amount of the diluted alkaline solution on the polymer film on the secondary side of the roll coater or rod coater in the step of washing the alkaline solution is 4 mL / m ² or less, and [2] Alkali The alkali saponification method according to any one of the above (1) to (4), wherein the amount of change in the width direction when the amount of phosphorus element on the surface of the polymer film obtained by the saponification method is measured by ESCA is less than 0.005 .
(6) The method for alkali saponification of a polymer film according to any one of (1) to (5) above, wherein the total number of roll coaters or rod coaters in the washing step is 2 to 10.
(7) The alkali saponification method according to any one of (1) to (6), wherein each step is carried out while the polymer film is conveyed.
(8) The alkali saponification method according to (7), wherein the polymer film is continuously conveyed.
(9) The hydroxide ion concentration of the alkaline solution is 0.1 to 5 mol / kg, and the coating amount is 1 to 50 mL / m ² . Alkali saponification method.
(10) The alkali agent of the alkali solution is an alkali metal hydroxide, the solvent of the alkali solution is an alcohol having 8 or less carbon atoms, a ketone having 6 or less carbon atoms, an ester having 6 or less carbon atoms, and The alkali saponification method according to any one of (1) to (9), comprising one or more organic solvents selected from polyhydric alcohols having 6 or less carbon atoms, and water.
(11) The alkaline solution contains at least one surfactant selected from nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants (1) to (10) ) Alkaline saponification method according to any of the above.
(12) The alkali saponification method according to (11), wherein the concentration of the surfactant is 0.001 to 10% by mass.
(13) The alkali saponification method according to claim 11 or 12, wherein the surfactant is a nonionic surfactant represented by the following general formula (1):
General formula (1) R1-L1-Q1
[Wherein R1 represents an alkyl group having 8 or more carbon atoms (simple or modified), L1 represents a single bond or a divalent linking group connecting R1 and Q1, and Q1 represents a polyoxyethylene unit (polymerization) Degree 5-150), a polyglycerin unit (degree of polymerization 3-30), and a nonionic hydrophilic group selected from hydrophilic sugar chain units].
(14) The surface tension of the alkali solution is 45 mN / m or less (35 ° C.), and the viscosity is 0.8 to 20 mPa · s (35 ° C.), any of (1) to (13) An alkali saponification method according to claim 1.
(15) The alkali saponification method according to any one of (1) to (14), wherein the polymer film is a cellulose acylate film.
(16) A surface saponified cellulose acylate film obtained by the alkali saponification method according to (15).
(17) An optical film comprising the surface saponified cellulose acylate film according to (16).
(18) A polarizing plate comprising the optical film according to (17).
(19) A liquid crystal display device comprising the polarizing plate according to (18).
(20) The liquid crystal display device according to (19), wherein the display mode is any one selected from TN, IPS, VA, and OCB.

  The polymer film saponified with alkali by any of the above methods (1) to (15) forms an alignment film on it, and then applies liquid crystalline molecules on the alignment film to fix the alignment of the liquid crystalline molecules. An optical compensation sheet can be produced by forming an optically anisotropic layer. Further, a polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films fixes an alignment film and liquid crystal molecule alignment on a polymer film When the optical compensation sheet is provided with an anisotropic layer in this order, the polymer film obtained by alkali saponifying the surface of the polymer film on which the alignment film is formed by any one of the above methods (1) to (15) Can be used advantageously. The polymer film saponified by alkali saponification by any of the above methods (1) to (15), particularly the surface saponified cellulose acylate film, is preferably used for an optical film. As an optical film, the optical compensation sheet and the transparent protective film of the polarizing film can be used for an antireflection film in which an antireflection layer such as a low refractive index layer is laminated.

According to the alkali saponification method of the polymer film of the present invention, in order to easily produce a large area optical film (optical compensation sheet) free from display defects in a liquid crystal display device, it can be appropriately alkali saponified, The polymer film that can be used as the transparent support of the compensation sheet can be subjected to alkali saponification treatment by means that does not impair the transparency and flatness, and the adhesion between the transparent support of the optical compensation sheet and the alignment film is high. The polymer film used as the transparent support can be subjected to alkali saponification so that it can be controlled with accuracy.
The polymer film saponified by the alkali saponification method of the polymer film of the present invention, when used as a transparent support for an optical compensation sheet, has a good surface shape while maintaining the adhesion with the conventional alignment film. In addition, the optical properties are excellent, the sheet thickness is thin, and when a liquid crystal display device is used, the image is clear and the cost can be reduced.
Furthermore, the polymer film saponified by the alkali saponification method of the polymer film of the present invention and the surface saponified cellulose acylate film can be suitably used for optical films.
Furthermore, the polarizing plate of the present invention comprises the optical film of the present invention, and more preferably has an optical compensation sheet, and is of high quality, and the liquid crystal display device of the present invention is an optical film of the present invention. It is preferable to have a high display quality provided with the polarizing plate of the present invention in which an optical compensation sheet is disposed on one side of the polarizing film.

Hereinafter, the alkali saponification method of a polymer film of the present invention, a surface saponified cellulose acylate film, an optical film, a polarizing plate having the optical film, and a liquid crystal display device having the polarizing plate will be described in detail.
First, the polymer film to which the alkali saponification method of the polymer film of the present invention is applied will be described, and then the alkali saponification method of the polymer film of the present invention and the surface saponified cellulose acylate film of the present invention will be described.

<Polymer film>
In the polymer film to which the alkali saponification method of the polymer film of the present invention is applied, examples of the polymer constituting the polymer film include cellulose esters (eg, cellulose mono-, di- and triacylates, and norbornene-based polymers, arton and ZEONEX (both are trade names)). Moreover, the polymer which is easy to express birefringence like the conventionally known polycarbonate and polysulfone may be sufficient. When used for an optical film, the film preferably has a light transmittance of 80% or more and a haze of 3% or less. In the case of a polymer that easily develops birefringence, it can be used as a transparent support by controlling the expression of birefringence by modifying the molecule as described in WO 00/26705 pamphlet. .
The thickness of the polymer film is preferably 20 to 200 μm, more preferably 30 to 150 μm, and most preferably 30 to 80 μm.

When the polymer film is used as an optical film, it preferably has a desired retardation value. The retardation value Re in the front direction and the retardation value Rth in the film thickness direction of the polymer film are calculated by the following formulas (I) and (II) using calculated values nx, ny, and nz described later, respectively. d is the thickness of the film whose unit is μm.
(I) Re = | nx−ny | × d
(II) Rth = {(nx + ny) / 2−nz} × d
When a polymer film is used as a transparent support for an optical compensation sheet, the retardation value varies depending on the liquid crystal display device in which the optical compensation sheet is used and the method of use thereof, and usually Re is 0 to 200 nm. And Rth is preferably adjusted in the range of 40 to 400 nm.
By setting the retardation value in the above range, the spread of the viewing angle of the display image of the display device can be increased.
In particular, as a transparent support for an optical compensation sheet used in the TN mode, Re is preferably in the range of 4 to 40 nm, and Rth is in the range of 50 to 200 nm. The transparent support for the compensation sheet preferably has Re of 10 to 70 nm and Rth of 70 to 400 nm.

When two optical compensation sheets are used for the liquid crystal display device, the Rth of the polymer film is preferably in the range of 70 to 250 nm. When one optical compensation sheet is used for the liquid crystal display device, the Rth of the polymer film is preferably in the range of 150 to 400 nm.
The birefringence (Δn: nx−ny) of the polymer film is preferably in the range of 0 to 0.020. Further, the birefringence {(nx + ny) / 2−nz} in the thickness direction of the polymer film is preferably in the range of 0.001 to 0.04.
In order to adjust the retardation value of the polymer film, a method of applying an external force such as stretching is generally used. As another method, there is a retardation adjusting agent as described later for adjusting the optical anisotropy. , Optionally added.

In the present invention, Re (λ) and Rth (λ) respectively represent the retardation in the front direction and the retardation in the thickness direction at the wavelength λ. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in a birefringence meter, for example, KOBRA21ADH (manufactured by Oji Scientific Instruments). Rth (λ) was tilted by + 40 ° with respect to the film normal direction with Re (λ) and the in-plane slow axis (determined by a birefringence meter, for example, KOBRA21ADH) as the tilt axis (rotary axis). The retardation value measured by making light of wavelength λnm incident from the direction, and the light of wavelength λnm made incident from the direction inclined −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis A birefringence meter, for example, KOBRA21ADH, calculates based on the retardation value measured in three directions in total, the assumed value of the average refractive index, and the input film thickness value. Here, as the assumed value of the average refractive index, “Polymer Handbook (John Wiley & Sons, Inc.)” and catalog values of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting the assumed value of the average refractive index and the film thickness, a birefringence meter such as KOBRA21ADH calculates nx, ny, and nz. This calculated nx (the refractive index in the slow axis direction in the film plane constituting the transparent support (the direction in which the refractive index is maximum)), ny (the fast axis direction in the film plane (the refractive index is minimum) Nz = (nx−nz) / (nx−ny) is further calculated from the refractive index in the direction) and nz (the refractive index in the thickness direction of the film).
In addition, in this specification, the value measured at 590 nm is shown unless otherwise specified.

[Cellulose acylate film and its raw materials]
As the polymer film, a cellulose acylate film is preferable. Cellulose acylate is produced by esterification from cellulose.
Cellulose acylate raw material cellulose used in the present invention includes cotton linter, kenaf, wood pulp (hardwood pulp, conifer pulp), etc., and any cellulose acylate obtained from any raw material cellulose can be used and mixed in some cases. May be used. Detailed descriptions of these raw material celluloses can be found in, for example, Plastic Materials Course (17) Fibrous Resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8) can be used, and the cellulose acylate film of the present invention is not particularly limited.

[Substitution degree of cellulose acylate]
Next, the cellulose acylate produced from the above cellulose will be described. The cellulose acylate is obtained by acylating the hydroxyl group of cellulose, and the substituent can be any acetyl group having 2 carbon atoms in the acyl group to those having 22 carbon atoms. In the cellulose acylate, the degree of substitution of cellulose with a hydroxyl group is not particularly limited. Obtainable. As a measuring method, it can carry out according to ASTM D-817-91.

  As described above, in the cellulose acylate, the degree of substitution of the cellulose with a hydroxyl group is not particularly limited, but the degree of acyl substitution with the hydroxyl group of cellulose is preferably 2.50 to 3.00. Furthermore, the substitution degree is preferably 2.75 to 3.00, and more preferably 2.85 to 3.00.

Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms may be an aliphatic group or an allyl group, and is not particularly limited. A mixture of the above may also be used. They are, for example, an alkylcarbonyl ester group, an alkenylcarbonyl ester group, an aromatic carbonyl ester group, an aromatic alkylcarbonyl ester group or the like, and each may have a further substituted group.
As these preferable acyl groups, acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group , Iso-butanoyl group, t-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, t-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are preferable, and acetyl group, propionyl group, butanoyl group are preferable. Groups are more preferred.

  Among the acyl substituents substituted on the hydroxyl group of cellulose described above, in the case of substantially consisting of at least two types of acetyl group / propionyl group / butanoyl group, when the total substitution degree is 2.50 to 3.00 The optical anisotropy of the cellulose acylate film can be reduced, which is preferable. In this case, the more preferable degree of acyl substitution is 2.60 to 3.00, and more preferably 2.65 to 3.00.

[Degree of polymerization of cellulose acylate]
The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average polymerization degree, and in cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. . If the degree of polymerization is too high, the viscosity of the cellulose acylate dope solution becomes high, and film production becomes difficult due to casting. If the degree of polymerization is too low, the strength of the produced film will decrease. The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). This is described in detail in JP-A-9-95538.
Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and most preferably 1.0 to 1.6. preferable.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular components can be performed by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. In order to obtain such a cellulose acylate, the moisture content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly a cellulose acylate having a moisture content of 0.7% by mass or less. It is. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In the present invention, in order to obtain the moisture content of the cellulose acylate, it is necessary to dry the cellulose acylate, and the method is not particularly limited as long as the desired moisture content is obtained. These cellulose acylates for use in the present invention are described in detail on page 7 to page 12 of the raw material cotton and the synthesis method thereof published by the Japan Society of Invention and Innovation (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). Are listed.

  The cellulose acylate may be used in the form of a substituent, a substitution degree, a polymerization degree, a molecular weight distribution, or the like as described above, and a single or a mixture of two or more different cellulose acylates can be used.

[Retardation adjuster]
When a polymer film is used as a transparent support for an optical compensation sheet, a retardation is applied to the polymer film that absorbs ultraviolet rays having a wavelength (λmax) shorter than 400 nm that gives the absorption maximum of the ultraviolet absorption spectrum of the solution. It is preferable to contain as a regulator. Examples of such compounds include ultraviolet absorbers such as phenyl salicylic acid, 2-hydroxybenzophenones, benzotriazoles, triphenyl phosphate. In addition, an aromatic compound having at least two aromatic rings, a triphenylene compound, a discotic compound (a compound containing a 1,3,5-triazine skeleton, a porphyrin skeleton in a molecule, or the like) is preferable. These compounds preferably have substantially no absorption in the visible light region.

{Aromatic compounds having at least two aromatic rings}
The retardation adjusting agent preferably contains at least one aromatic compound having at least two aromatic rings (hereinafter also referred to as “aromatic compound A”). The aromatic ring of the aromatic compound may be an aromatic hetero ring in addition to the aromatic hydrocarbon ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable.

  The number of aromatic rings contained in the aromatic compound A is preferably 2 to 20, and more preferably 2 to 12. In the case of having three or more aromatic rings, the conformation of at least two aromatic rings should not be sterically hindered. The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). From the viewpoint of the retardation increasing function, any of (a) to (c) may be used. Specific examples include those described in JP-A-2002-131537, paragraph numbers [0016] to [0023]. Furthermore, in the case of the above (b) or (c), it is preferable that the conformation of the two aromatic rings does not sterically hinder.

Examples of the aromatic compound A include a rod-like compound having a linear molecular structure having the same content as described in paragraphs [0011] to [0031] of JP-A No. 2002-363343, paragraph of JP-A No. 2000-111194. A compound containing two aromatic rings having the same steric hindrance conformation as described in the numbers [0011] to [0085], and containing at least one aromatic ring as a substituent; Examples include 3,5-triazine compounds or compounds having a porphyrin skeleton (compounds described in JP-A No. 2001-166144).
In particular, 1,3,5-triazine compounds containing at least one aromatic ring as a substituent are preferable (the triazine ring becomes another aromatic ring). Specific examples include 1,3,5-triazine compounds described in general formula (I) described in paragraph No. [0016] of JP-A No. 2001-166144.
The molecular weight of the aromatic compound A is preferably 300 to 800.

  In order to adjust the content of the aromatic compound A to a desired retardation, the type and amount of the retardation modifier are selected and used. In the case of a cellulose acylate film, for example, in the case of a cellulose acylate film, it does not cause problems such as solubility in a film-forming composition when making a film, insolubilization or precipitation during film formation. And it is preferable to use in the range of 0.01-30 mass parts, and it is more preferable to use in the range of 0.05-25 mass parts. More preferably, it is 0.1-20 mass parts.

[Plasticizer]
It is preferable to add a conventionally known plasticizer to the polymer film in order to improve the mechanical properties of the film or to increase the drying speed. Examples of the plasticizer include phosphate esters, carboxylic acid esters {as carboxylic acids, aliphatic carboxylic acids, oxycarboxylic acids (citric acid, malic acid, etc.), aromatic carboxylic acids (phthalic acid, etc.)}, etc. Inventive Association Public Technique No. 2001-1745 (issued March 15, 2001, Invention Association) p. 16 and the like. Further, an esterified compound of an alkane polyol and a carboxylic acid (JP-A-11-124445, JP-A-2001-247717, etc.) and the like are also preferable.
For example, in the case of a cellulose acylate film, the addition amount of the plasticizer is preferably 0.05 to 25 parts by mass, more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the cellulose acylate.

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the polymer film. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable from the viewpoint of low turbidity, and silicon dioxide is particularly preferable. 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 g / liter. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter, more preferably 100 to 200 g / liter. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, and these fine particles are present as aggregates of primary particles in the film, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably from 0.2 μm to 1.5 μm, more preferably from 0.4 μm to 1.2 μm, and most preferably from 0.6 μm to 1.1 μm. The primary and secondary particle sizes were determined by observing the particles in the film with a scanning electron microscope and determining the diameter of a circle circumscribing the particles as the particle size. Also, 200 particles are observed at different locations, and the average value is taken as the average particle diameter.

  As the fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

In order to obtain a polymer film having particles having a small secondary average particle diameter, several methods are conceivable when preparing a dispersion of fine particles. Hereinafter, a cellulose acylate film will be described as an example. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are stirred and mixed in advance, adding the fine particle dispersion to a small amount of a separately prepared cellulose acylate solution, stirring and dissolving, and further mixing with a main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add the fine particles to this and disperse with a disperser to make this fine particle additive solution, and mix this fine particle additive solution with the dope solution using an in-line mixer. There is also a way to do it. The present invention is not limited to these methods, but the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

[Other additives]
The polymer film used as the transparent support further includes an ultraviolet ray inhibitor (for example, a hydroxybenzophenone compound, a benzotriazole compound, a salicylic acid ester compound, a cyanoacrylate compound, etc.), a deterioration inhibitor (for example, an antioxidant). , Peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, light stabilizers (hindered amines, etc.)}, release agents, antistatic agents, etc. may be added. Specifically, the above-mentioned public technical number No. 2001-1745 p. Materials described in detail in 17-22 are preferably used.
The addition amount of these additives is preferably 0.001 to 40 parts by mass, more preferably 0.005 to 30 parts by mass with respect to 100 parts by mass of the polymer.

[Rate of compound addition]
Regarding the ratio of compound addition in the polymer film, for example, in a cellulose acylate film, the total amount of compounds having a molecular weight of 3000 or less is preferably 5 to 45% with respect to the mass of cellulose acylate. More preferably, it is 10 to 40%, and more preferably 15 to 30%. As mentioned above, these compounds are retardation adjusting agents, UV inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, etc., and the molecular weight is preferably 3000 or less, more preferably 2000 or less. In fact, 1000 or less is even better. If the total amount of these compounds is 5% or more, the properties of cellulose acylate alone are difficult to appear, and for example, the optical performance and physical strength are less likely to vary with changes in temperature and humidity. Moreover, if the total amount of these compounds is 45% or less, it does not exceed the limit of compatibility of the compounds in the cellulose acylate film, and may be deposited on the film surface or the film may become cloudy (crying out of the film). Absent.

[Method for producing polymer film as transparent support]
[Solvent for polymer film]
In the present invention, the transparent support is preferably produced by a solution casting method (solvent casting method). In the solution casting method, a solution (dope) in which the polymer or the like is dissolved in an organic solvent is used. Manufactured.
Examples of the organic solvent to be used include conventionally known organic solvents. For example, those having a solubility parameter in the range of 17 to 22 are preferable. Solubility parameters are described in, for example, J. The content described in “PolymerHandbook (4th.edition)” by Brandrup, EH, etc., VII / 671 to VII / 714. Lower aliphatic hydrocarbon chloride, lower aliphatic alcohol, ketone having 3 to 12 carbon atoms, ester having 3 to 12 carbon atoms, ether having 3 to 12 carbon atoms, fat having 5 to 8 carbon atoms Group hydrocarbons and aromatic hydrocarbons having 6 to 12 carbon atoms.
The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.
Specifically, for example, the aforementioned public technical number 2001-1745 p. And compounds described in detail in 12-16.

In particular, in the present invention, the solvent is preferably used by mixing two or more kinds of organic solvents, and particularly preferred organic solvents are three or more kinds of mixed solvents different from each other, and the first solvent has the number of carbon atoms. A ketone having 3 to 4 carbon atoms and an ester having 3 to 4 carbon atoms, or a mixture thereof, and the second solvent is selected from ketones having 5 to 7 carbon atoms or acetoacetic acid ester; It is preferably selected from alcohol having a boiling point of 30 to 170 ° C. or hydrocarbon having a boiling point of 30 to 170 ° C.
In particular, it is preferable from the viewpoint of solubility of the polymer such as cellulose acylate to use 20 to 90% by mass of acetate, 5 to 60% by mass of ketones, and 5 to 30% by mass of alcohols.
In these mixed solvents, the blending ratio of alcohols is 2 vol% or more and 40 vol% or less, more preferably 3 vol% or more and 30 vol% or less, and further preferably 5 vol% or more and 20 vol% or less.
The alcohol is preferably a monoalcohol or dialcohol having 1 to 8 carbon atoms or a fluoroalcohol having 2 to 10 carbon atoms, more preferably methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, cyclohexanol, ethylene glycol, 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3- Tetrafluoro-1-propanol is mentioned. These may be added alone or in admixture of two or more.
In particular, a non-halogen organic solvent system such as a non-chlorine solvent that does not contain a halogenated hydrocarbon can be mentioned as a preferred embodiment.
Technically, halogenated hydrocarbons such as methylene chloride can be used without problems, but from the viewpoint of the global environment and working environment, it is preferable that the organic solvent is substantially free of halogenated hydrocarbons. “Substantially free” means that the proportion of halogenated hydrocarbon in the organic solvent is less than 5% by mass (preferably less than 2% by mass). Moreover, it is preferable that chlorinated hydrocarbons such as methylene chloride are not detected at all from the produced transparent support (cellulose acylate film or the like).

Non-chlorine organic solvent systems used in the present invention are described, for example, in paragraphs [0021] to [0025] of JP-A No. 2002-146043, paragraph numbers [0016] to [0021] of JP-A No. 2002-146045, and the like. Examples of the solvent system are as follows.
An aromatic or aliphatic hydrocarbon having 5 to 10 carbon atoms may be added to the solvent in an amount of 0 to 10 vol%. Examples of the hydrocarbon include cyclohexane, hexane, benzene, toluene, and xylene.
In addition to the above organic solvents, the dope used in the present invention may contain fluoroalcohol in an amount of 10% by mass or less, more preferably 5% by mass or less of the total amount of the solvent, thereby improving the transparency of the film or increasing the solubility. Is preferable. Examples of the fluoroalcohol include compounds described in paragraph No. [0020] of JP-A-8-143709 and paragraph No. [0037] of JP-A-11-60807. These fluoroalcohols may be used alone or in combination.
Hereinafter, although the cellulose acylate film used suitably as a polymer film in this invention is demonstrated to an example, when producing a film using polymers other than a cellulose acylate, it can apply similarly.
When preparing a cellulose acylate solution, the container may be filled with an inert gas such as nitrogen gas. The viscosity of the cellulose acylate solution immediately before film formation may be within a range that allows casting, and it is usually preferably adjusted to a range of 10 ps · s to 2000 ps · s, particularly 30 ps · s to 400 ps · s is preferred.

  Regarding the preparation of the dope, the dissolution method is not particularly limited, and may be a room temperature dissolution method, a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP-A-2000-53784, Kaihei 11-322946, JP-A-11-322947, JP-A-2-276830, JP-A-2000-273239, JP-A-11-71463, JP-A-04-259511, JP-A-2000-273184, JP-A-11-323017, JP-A-11-323017 The preparation method of the cellulose acylate solution as described in each gazette of 11-302388 etc. is mentioned. The above-described method for dissolving cellulose acylate in an organic solvent can be applied to these techniques as appropriate in the present invention as long as it is within the scope of the present invention. Further, the cellulose acylate dope solution is usually subjected to concentration and filtration. Similarly, the above-mentioned public technical number 2001-1745 p. 25 in detail. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.

(Method of adding and mixing fine particles)
When fine particles are added to the cellulose acylate solution, the method is not particularly limited as long as the coarse particles as described above are not present, and a desired cellulose acylate solution can be obtained by any method as described above. If you can, there is no problem.
A method in which the fine particles are mixed and dispersed in a dope after preparing a dispersion separately from the dope adjustment described above. For example, the following methods can be mentioned.
(1) After stirring and mixing a solvent (same as the organic solvent used for the dope) and fine particles, a fine particle dispersion is made with a disperser and added to the dope solution and stirred.
(2) After the above solvent and fine particles are stirred and mixed, a fine particle dispersion is made with a disperser, and a small amount of cellulose acylate is added to the solvent and dissolved with stirring. The fine particle dispersion obtained by adding the fine particle dispersion and stirring to this is sufficiently mixed with the dope solution using an in-line mixer.
(3) A small amount of binder is added to the above solvent and dissolved by stirring. Fine particles are added to the solvent and dispersed with a disperser to obtain a fine particle dispersion. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer. Examples of the binder include cellulose acylate. Preferably, cellulose acylate used for dope is used.

For the dispersion, a conventionally known wet dispersion method can be used.
Examples of the wet media disperser include conventionally known ones such as a sand grinder mill (eg, bead mill with pins), a dyno mill, a high-speed impeller mill, a pebble mill, a roller mill, an attritor, a colloid mill, and a ball mill. In particular, a sand grinder mill, a dyno mill, and a high-speed impeller mill are preferable for dispersing the oxide fine particles of the present invention in ultrafine particles.
In order to disperse into the size of ultrafine particles not containing coarse particles in the above range, a wet dispersion method using media having an average particle size of less than 0.8 mm is preferred. As the media used together with the disperser, the average particle size is less than 0.8 mm, and when the average particle size is within this range, the inorganic fine particle size is 1 to 100 nm and the particle size is uniform. Ultra fine particles can be obtained. The average particle size of the media is preferably 0.5 mm or less, more preferably 0.05 to 0.3 mm.
Moreover, as a medium used for wet dispersion, beads are preferable. Specific examples include zirconia beads, glass beads, ceramic beads, steel beads, etc., and 0.05 to 0.2 mm from the viewpoint of durability and ultrafine particle formation such that the beads are not easily broken during dispersion. Zirconia beads are particularly preferred.

  As the medialess disperser, there are an ultrasonic type, a centrifugal type, a high pressure type, and the like. The high-pressure dispersion device preferably has a maximum pressure condition of 9.8 MPa or more in a thin tube having a tube diameter of 1 to 2000 μm, for example. More preferably, it is 19.6 MPa or more. At that time, it is preferable that the maximum reaching speed reaches 100 m / sec or more, and the heat transfer speed reaches 420 kJ / hr or more. The high-pressure disperser includes an ultra-high-pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer, and other manton gorin type high-pressure dispersers such as homogenizer manufactured by Izumi Food Machinery, Sanwa Machinery Co., Ltd. ) UHN-01 manufactured by the company.

  Furthermore, in order to remove coarse aggregates in the dispersion, the dispersion particles in the dispersion satisfy the above-mentioned range of the average particle diameter and the monodispersibility of the particle diameter. It is also preferable to arrange the filter medium so as to be microfiltered. The filter medium for fine filtration preferably has a filtration particle size of 25 μm or less. The type of filter medium for microfiltration is not particularly limited as long as it has the above performance, and examples thereof include a filament type, a felt type, and a mesh type. The material of the filter medium for finely filtering the dispersion is not particularly limited as long as it has the above-described performance and does not adversely affect the coating solution, and examples thereof include stainless steel, polyethylene, polypropylene, and nylon.

  Additives other than the fine particles described above may be included, for example, at the stage of mixing cellulose acylate and a solvent, or an additive may be added after preparing a mixed solution with cellulose acylate and a solvent. Further, it may be added and mixed immediately before casting the dope, which is a so-called immediately preceding addition method, and the mixing is used by installing screw-type kneading online. Mixing of these additives may be performed by adding the additive itself, but it may be dissolved in advance using a solvent or binder (preferably cellulose acylate) or may be dispersed and stabilized as the case may be. Use is also a preferred embodiment.

Next, a method for producing a cellulose acylate film suitable as a polymer film used as a transparent support will be described. As a method and equipment for producing a cellulose acylate film, a conventionally known solution casting film forming method and solution casting film forming apparatus called a drum method or a band method used for producing a cellulose acylate film are used.
Explaining the film forming process, a dope (cellulose acylate solution) prepared from a dissolving machine (kettle) is temporarily stored in a storage kettle, and bubbles contained in the dope are defoamed for final preparation. It is important to remove foreign matters from the prepared dope by microfiltration. Specifically, it is preferable to use a filter having a pore size as small as possible within a range in which components in the dope solution are not removed. For the filtration, a filter having an absolute filtration accuracy of 0.1 to 100 μm is used, and a filter having an absolute filtration accuracy of 0.1 to 25 μm is preferably used. The thickness of the filter is preferably 0.1 to 10 mm, and more preferably 0.2 to 2 mm. In that case, it is preferable to filter at a filtration pressure of 15 kgf / cm ² or less, more preferably 10 kgf / cm ² or less, and further 2 kgf / cm ² or less.

In addition, for microfiltration, it is also preferable to perform filtration several times with the pore diameter of the filter being successively reduced.
The type of filter medium for microfiltration is not particularly limited as long as it has the above performance, and examples thereof include a filament type, a felt type, and a mesh type. The material of the filter medium for finely filtering the dispersion is not particularly limited as long as it has the above performance and does not adversely affect the coating solution. Examples thereof include stainless steel, polyethylene, polypropylene, and nylon.

  The prepared dope is fed from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the rotational speed, and the dope is run endlessly from the die (slit) of the pressure die. The dope film (also referred to as a web) is peeled off from the metal support at the peeling point where the metal support has been cast evenly on the metal support and the metal support has substantially gone around. Both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose.

  The metal support used in the casting step preferably has a surface having an arithmetic average roughness (Ra) of 0.015 μm or less and a ten-point average roughness (Rz) of 0.05 μm or less. More preferably, the arithmetic average roughness (Ra) is 0.001 to 0.01 μm, and the ten-point average roughness (Rz) is 0.001 to 0.02 μm. More preferably, the (Ra) / (Rz) ratio is 0.15 or more. Thus, the surface shape of the film after film formation can be controlled within the scope of the present invention by setting the surface roughness of the metal support within a predetermined range.

About each of these manufacturing processes (Categorized into casting (including co-casting), metal support, drying, peeling, stretching, etc.), the above-mentioned public technical numbers 2001-1745 p. The contents described in detail in 25-30 can be mentioned. In the casting step, one type of cellulose acylate solution may be cast in a single layer, or two or more types of cellulose acylate solutions may be cast simultaneously and / or sequentially.
In particular, in the step of forming a film from a dope comprising the composition as described above, a drying step is important in order to carry out the added compound without aggregation or uneven distribution.

[Drying process]
The drying of the dope on the support is generally performed by applying hot air from the surface side of the support (drum or belt), that is, the surface of the web on the support, or applying hot air from the back of the drum or belt, There is a liquid heat transfer method in which the temperature controlled liquid is contacted from the back side opposite to the belt or drum dope casting surface and the drum or belt is heated by heat transfer to control the surface temperature. The method is preferred. The surface temperature of the support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the support, the temperature may be set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent among the solvents used. preferable.

The drying temperature in the drying step of the polymer film thus formed is preferably 30 to 250 ° C, particularly preferably 40 to 180 ° C. Further, in order to remove the residual solvent, it is preferably used to dry at 50 to 160 ° C., and in that case, the residual solvent is evaporated by drying with high-temperature air whose temperature is changed successively. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, and may be appropriately selected according to the type and combination of the solvents used. The amount of residual solvent in the final finished film is preferably 2% by mass or less, and more preferably 0.4% by mass or less in order to obtain a film having good dimensional stability. In the present invention, the stripping agent of the present invention can further reduce the stripping time and lower the resistance at the time of stripping, resulting in a planar shape (lateral unevenness at the time of stripping and unstriped gelled residue). It is possible to obtain a polymer film that does not deteriorate the roughness.
In the drying process after peeling from the support, the film tends to shrink in the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, a method of drying the whole drying process or a part of the process as shown in Japanese Patent Application Laid-Open No. 62-46625 while holding the width at both ends of the web with a clip in the width direction (tenter method) Is preferred.

The speed at which the polymer film is produced varies depending on the length of the belt, the drying method, the dope solvent composition, and the like, but is almost determined by the amount of residual solvent when the web is peeled from the belt. In other words, if the solvent concentration in the vicinity of the belt surface in the thickness direction of the dope film is too high, the dope remains on the belt when it is peeled off, which hinders the next casting. This is because the web strength is required to withstand the peeling force. The amount of residual solvent at the time of peeling differs depending on the drying method on the belt or drum, and the method of transferring heat from the belt or the back of the drum is more effective than the method of drying by blowing air from the dope surface. Can be reduced.
Specifically, the drying is preferably performed under the condition that the residual solvent amount in the transparent support is in the range of 0.01 to 1.5% by mass. More preferably, it is 0.01-1.0 mass%.
In the casting step, it is preferable to perform uniaxial stretching only in one direction such as the casting direction (longitudinal direction) or biaxial stretching in the casting direction and the other direction (lateral direction).
Furthermore, the dope may be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, a UV absorbing layer, a polarizing layer).

[Stretching treatment]
In the production of the cellulose acylate film as the transparent support, it is preferable to stretch in at least one direction along the film surface. That is, it is more preferable that the film is stretched in at least one of the longitudinal direction and the transverse direction, or further, multiaxially stretched by combining these. The stretch ratio of the film (ratio of increase due to stretching relative to the original length) is preferably 0.5 to 300%, more preferably 1 to 200%, and particularly preferably 1 to 150%. Specifically, the above-mentioned public technical number No. 2001-1745 p. The content described in detail in 29-30 is mentioned.

[Winding process]
In the method for producing a cellulose acylate film in the present invention, drying is finished, and the film is wound up to a predetermined length in a roll shape by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film that is an optical member for an electronic display, which is the main use of the cellulose acylate film of the present invention, in addition to the solution casting film forming apparatus, an undercoat layer In many cases, a coating device is added for surface processing of a film such as an antistatic layer or a protective layer. These are described in detail on pages 25-30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society for Invention). Including), metal support, drying, peeling and the like, and can be preferably used in the present invention.
Moreover, 10-120 micrometers is preferable, as for the thickness of a cellulose acylate film, 20-110 micrometers is more preferable, and 30-90 micrometers is more preferable.

[Characteristics of polymer film as transparent support]
And in this invention, it is preferable that the polymer film before hydrophilizing the surface (surface saponification) has the following characteristics.

(Surface shape of transparent support)
It is preferable that the surface of the polymer film before the hydrophilization treatment has an arithmetic average roughness (Ra) of surface unevenness of the film based on JISB0601-1994, and is a ten-point average roughness. (Rz) is preferably 0.0001 to 0.3 μm, and the maximum height (Ry) is preferably 0.0002 to 1 μm. More preferably, the arithmetic average roughness (Ra) is 0.0001 to 0.08 μm, the ten-point average roughness (Rz) is 0.0001 to 0.1 μm, and the maximum height (Ry) is 0.0002 to 0.00. 5 μm. More preferably, the arithmetic average roughness (Ra) is in the range of 0.0001 to 0.015 μm, the ten-point average roughness (Rz) is in the range of 0.002 to 0.05 μm, and the maximum height (Ry). Is 0.0002 to 0.05 μm. Particularly preferably, the arithmetic average roughness (Ra) is in the range of 0.001 to 0.010 μm, the ten-point average roughness (Rz) is in the range of 0.002 to 0.025 μm, and the maximum height (Ry) is 0.0002 to 0.04 μm.
Furthermore, in the fine surface irregularity form, the ratio (Ra / Rz) of arithmetic average roughness (Ra) to ten-point average roughness (Rz) is 0.15 or more, and the surface of the film based on JIS B0601-1994 It is preferable that the average interval (Sm) of the unevenness is 5 μm or less. Here, the relationship between Ra and Rz indicates the uniformity of surface irregularities. Preferably, the (Ra / Rz) ratio is 0.17 or more, and the average interval (Sm) is 0.001 to 1 μm.
The concave and convex shapes on the film surface can be evaluated by a transmission electron microscope (TEM), an atomic force microscope (AFM), or the like.

[Hygroscopic expansion coefficient]
When a polymer film is used for the transparent support of the optical compensation sheet, particularly when a cellulose acylate film is used as the polymer film, the hygroscopic expansion coefficient of the cellulose acylate film may be 30 × 10 ⁻⁵ /% RH or less. It is preferably 15 × 10 ⁻⁵ /% RH or less, more preferably 10 × 10 ⁻⁵ /% RH or less. Further, the hygroscopic expansion coefficient is preferably small, but usually a value of 1.0 × 10 ⁻⁵ /% RH or more. The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature.
By adjusting this hygroscopic expansion coefficient, it is possible to prevent frame-like transmittance increase, that is, light leakage due to distortion, while maintaining the optical compensation function of the optical compensation sheet.

The method for measuring the hygroscopic expansion coefficient is shown below. That is, a sample having a width of 5 mm and a length of 20 mm is cut out from the produced cellulose acylate film, and one end is fixed and hung in an atmosphere of 25 ° C. and 20% RH (R0). A weight of 0.5 g is hung on the other end and left for 10 minutes to measure the length (L0). Next, with the temperature kept at 25 ° C., the humidity is set to 80% RH (R1), and the length (L1) is measured. The hygroscopic expansion coefficient is calculated by the following formula.
Hygroscopic expansion coefficient [/% RH] = {(L1-L0) / L0} / (R1-R0)
In order to reduce the dimensional change due to moisture absorption of the produced transparent support such as cellulose acylate film, it is preferable to add a compound having a hydrophobic group or fine particles. As the compound having a hydrophobic group, a material corresponding to a plasticizer or a degradation inhibitor having a hydrophobic group such as an aliphatic group or an aromatic group in the molecule is particularly preferably used. The amount of these compounds added is preferably in the range of 0.01 to 10% by mass with respect to the solution (dope) to be adjusted. In addition, the free volume in the transparent support such as a cellulose acylate film may be reduced. Specifically, the smaller the amount of residual solvent during film formation by the solvent casting method described later, the smaller the free deposition. It is preferable to dry on the conditions that the amount of residual solvents with respect to transparent supports, such as a cellulose acylate film, is 0.01-1.5 mass%.

[Moisture permeability and water content]
The moisture permeability of a transparent support such as a cellulose acylate film used for the optical compensation sheet is ^{2 to} 150 g / m ² · 24 h in JIS standard JISZ0208, condition B (temperature 40 ° C., humidity 90% RH). More preferably 10~120g / m ² · 24h, and particularly preferably 10~100g / m ² · 24h. If it exceeds 150 g / m ² · 24 h, the absolute value of the humidity dependence of the Re value and Rth value of the polymer film used as the transparent support tends to exceed 0.5 nm /% RH, and it is transparent to the optical compensation sheet. When used as a support, the absolute value of the humidity dependence of the Re value and Rth value of the optical compensation sheet tends to exceed 0.3 nm /% RH, and this optical compensation sheet and polymer film are transparent. When a polarizing plate used as a protective film is incorporated in a liquid crystal display device, it is not preferable because it may cause a change in color or a decrease in viewing angle. Further, when the moisture permeability is less than ² g / m ² · 24 h, when the polarizing plate is produced by being attached to both surfaces of the polarizing film, the transparent support prevents the adhesive from being dried, resulting in poor adhesion.
The method of measuring moisture permeability is described in “Polymer Properties II” (Polymer Experiment Course 4 Kyoritsu Shuppan) p. 285-294: The method described in the measurement of vapor permeation amount (mass method, thermometer method, vapor pressure method, adsorption amount method) can be applied.

The water content of the transparent support such as a cellulose acylate film is 0.3 to 0.3 at 30 ° C. and 85% RH regardless of the film thickness so as not to impair the adhesion to a water-soluble polymer such as polyvinyl alcohol. It is preferably 12 g / m ² . More preferably, it is 0.5-5 g / m < ² >. If it is greater than 12 g / m ^{2, the} dependence of retardation due to humidity changes becomes too large, which is not preferable.

[Mechanical properties]
The curl value in the width direction of the polymer film used as the transparent support is preferably −10 / m to + 10 / m. When the polymer film is used as a transparent support for an optical compensation sheet, the surface treatment, rubbing treatment described later, alignment film, and installation of an optically anisotropic layer are performed on a long and wide transparent support. In addition, when the curl value in the width direction of the transparent support is outside the above range, the handling of the film may be hindered and the film may be cut. In addition, the film is strongly in contact with the transport roll at the edge and center of the film, so it is easy to generate dust, and foreign matter adheres to the film. It became clear that the value was exceeded. In addition, curling within the scope of the present invention is preferable because it can reduce color spot failure that is likely to occur when an optically anisotropic layer is installed, and can prevent bubbles from entering when a polarizing film is bonded.
The curl value can be measured according to a measurement method (ANSI / ASCPH1.29-1985) defined by the American National Standards Institute.

The scratch strength is preferably 1 g or more, more preferably 5 g or more, and particularly preferably 10 g or more.
Within these ranges, the scratch resistance and handling properties of the film surface can be maintained without problems.
The scratch strength can be evaluated with a load (g) by which the surface of the support is scratched using a sapphire needle having a cone apex angle of 90 degrees and a tip radius of 0.25 m, and the scratch mark can be visually confirmed.

[Optical anisotropy]
When the polymer film is used as a transparent support for an optical compensation sheet, it preferably exhibits the optical anisotropy, and the Re retardation value and Rth retardation value representing the degree thereof are as described above. is there.

  The calculated birefringence (Δn: nx−ny) of the polymer film is preferably 0.000025 to 0.0088, more preferably 0.0003 to 0.005 with respect to a wavelength of 550 nm. The birefringence {(nx + ny) / 2−nz} in the thickness direction calculation is preferably 0.0006 to 0.02, more preferably 0.001 to 0.007, with respect to the wavelength of 550 nm. It is.

[Glass Transition Temperature Tg of Film]
The glass transition temperature Tg of the cellulose acylate film preferably used as the polymer film in the present invention is 80 to 165 ° C. From the viewpoint of heat resistance, Tg is more preferably 100 to 160 ° C, and particularly preferably 110 to 150 ° C. The glass transition temperature Tg is measured with a differential scanning calorimeter (DSC2910, T.A. Instrument) measuring 10 mg of a cellulose acylate film sample from room temperature to 200 ° C. at a heating / cooling rate of 5 ° C./min. The glass transition temperature Tg was calculated.

[Haze of film]
The haze of the cellulose acylate film preferably used as the polymer film in the present invention is preferably 3% or less. More preferably, it is 0.01 to 2.0%, more preferably 0.05 to 1.5%, and particularly preferably 0.1 to 1.0%. When used as an optical film, the transparency of the film is important. The haze was measured by measuring a cellulose acylate film sample 40 mm × 80 mm at 25 ° C. and 60% RH with a haze meter (HGM-2DP, Suga Test Instruments) according to JIS K-6714.

<Method for Alkaline Saponification of Polymer Film of the Present Invention as Surface Treatment of Optical Film>
The method for alkaline saponification of a polymer film of the present invention includes a step of washing an alkaline solution present on the polymer film using an alkaline washing solution containing water or water and an organic solvent.

In addition to the above, the present invention preferably further includes a step of applying an alkaline solution to a polymer film having a temperature of room temperature or higher. That is,
Applying an alkaline solution to a polymer film having a temperature of room temperature or higher,
It is preferable to have the process of wash | cleaning the alkaline solution which exists on a polymer film using the alkaline washing | cleaning liquid containing water or water and an organic solvent.

In addition to these steps, the present invention preferably further includes a step of maintaining the temperature of the polymer film at room temperature or higher. That is,
Applying an alkaline solution to a polymer film having a temperature of room temperature or higher,
Maintaining the temperature of the polymer film above room temperature,
It is preferable to have the process of wash | cleaning the alkaline solution which exists on a polymer film using the alkaline washing | cleaning liquid containing water or water and an organic solvent.

Furthermore, the present invention preferably further comprises a step of heating the polymer film to room temperature or higher in advance in addition to these steps. That is,
Heating the polymer film above room temperature in advance,
Applying an alkaline solution to the polymer film;
Maintaining the temperature of the polymer film above room temperature,
It is preferable to have the process of wash | cleaning the alkaline solution which exists on a polymer film using the alkaline washing | cleaning liquid containing water or water and an organic solvent.

[Alkaline saponification]
As the alkali saponification, any method such as a method of immersing the optical film in an alkali solution or a method of spraying or coating an alkali solution on the surface of the optical film can be used. In the present invention, it is more preferable to perform alkali saponification by an application method that can uniformly saponify only one surface of the optical film, that is, a saponification step by applying an alkaline solution to the polymer film. On the other hand, in the saponification by the dipping method, in particular, in the alkali saponification containing an organic solvent, the treatment speed can be remarkably increased as compared with those not containing an organic solvent.

The saponification is preferably performed at a temperature at which deformation of the film to be saponified, alteration of the alkaline solution, etc. does not occur, and at a treatment temperature in a range not exceeding 120 ° C., more preferably from 25 ° C. to 120 ° C. It is preferable to carry out at a temperature of 100 ° C. or higher.
The saponification time is determined by appropriately adjusting the alkali solution and the temperature at the time of saponification, but it is preferably performed in the range of 1 second to 60 seconds.

  Furthermore, the alkali saponification method of the present invention preferably includes a step of applying an alkaline solution to a polymer film having a temperature of room temperature (25 ° C.) or higher. Furthermore, it is preferable to have a step of maintaining the temperature of the polymer film at least above room temperature in addition to these steps. The temperature at the time of saponification can be made into the said desired temperature, and is preferable.

Further, in the present invention, it is preferable that the method further includes a step of adjusting the polymer film to a predetermined temperature (a temperature equal to or higher than room temperature) before applying the alkaline solution in order to bring the polymer film to a predetermined temperature. . It is also preferable to combine the step of adjusting the alkaline solution to a predetermined temperature in advance. In particular, it is preferable to have a step of heating to a predetermined temperature (a temperature equal to or higher than room temperature) before application.
“To make the polymer film at a predetermined temperature”, “Polymer film having a temperature of room temperature or higher” and “Maintaining the temperature of the polymer film at room temperature or higher” means that the temperature of the entire polymer film needs to be a predetermined temperature. In other words, the surface to be treated by saponification, that is, the surface of the polymer film in which the saponification reaction occurs may be at a predetermined temperature.
Here, as means for heating the polymer film to a temperature higher than room temperature, direct heating by hot air collision (blowing), contact heat transfer by a heating roll, induction heating by a microwave, or radiant heat heating by an infrared heater is preferably used. it can. In particular, contact heat transfer using a heating roll is preferable in that it has a high heat transfer efficiency and can be performed with a small installation area, and that the film temperature rises quickly at the start of conveyance. A general double jacket roll or electromagnetic induction roll (manufactured by Tokuden) can be used. The film surface temperature after heating is preferably 25 to 120 ° C, more preferably 25 to 100 ° C.
The means for maintaining the temperature of the polymer film is selected in consideration of the fact that one side of the film is wet with an alkaline solution. Hot air collision (spraying) on the opposite surface of the coating, contact heat transfer with a heating roll, induction heating with a microwave, radiant heat heating with an infrared heater, etc. can be preferably used. Infrared heaters are preferred because they can be heated without contact and without air flow, so that the influence on the alkaline solution coating surface can be minimized. As the infrared heater, an electric, gas, oil or steam far infrared ceramic heater can be used. A commercially available infrared heater (for example, manufactured by Noritake Company Limited) may be used. An oil-type or steam-type infrared heater using oil or steam as the heat medium is preferable from the viewpoint of explosion prevention in an atmosphere in which an organic solvent coexists. The temperature of the polymer film may be the same as or different from the temperature heated before applying the alkaline solution. Further, the temperature may be changed continuously or stepwise during the saponification reaction. The film temperature is 20 ° C to 120 ° C, preferably 25 ° C to 100 ° C. For the detection of the film temperature, a commercially available non-contact infrared thermometer can be used, and feedback control may be performed on the heating means in order to control the temperature within the above range.
The time for maintaining the temperature range from application of the alkaline solution to washing off depends on the conveyance speed described later, but is preferably maintained for 1 second to 5 minutes, more preferably 2 to 100 seconds. It is particularly preferred to hold for ~ 50 seconds.
These means are preferable because the alkaline solution on the film surface can be adjusted to room temperature or higher.

(Alkaline solution)
In the present invention, the alkaline solution used for alkali saponification is preferably an alkaline solution having a pH of 11 or more. More preferably, the pH is 12-14.

Examples of the alkaline agent used in the alkaline solution include inorganic alkaline agents such as sodium hydroxide, potassium hydroxide and lithium hydroxide, diethanolamine, triethanolamine, DBU (1,8-diazabicyclo [5,4,0]. -7-undecene), DBN (1,5-diazabicyclo [4,3,0] -5-nonene), tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethyl Organic alkali agents such as butylammonium hydroxide are also used. These alkaline agents can be used alone or in combination of two or more, and a part thereof may be added in the form of a salt, for example, halogenated.
Among these alkali agents, alkali metal hydroxides are preferable, and the use of sodium hydroxide or potassium hydroxide is particularly preferable because the pH can be adjusted in a wide range by adjusting these amounts.

  The concentration of the alkaline agent in the alkaline solution is determined according to the type of alkaline agent to be used, the reaction temperature, and the reaction time, but the content of the alkaline agent is such that the hydroxide ion concentration in the alkaline solution is 0.1 to 5 mol. / Kg is preferable, and 0.3 to 3 mol / kg is more preferable.

  The solvent of the alkaline solution of the present invention is preferably a mixed solution of water and a water-soluble organic solvent. Any organic solvent that is miscible with water can be used as the organic solvent, but those having a boiling point of 120 ° C. or lower, more preferably 60 to 120 ° C., and particularly preferably 60 to 100 ° C. or lower are preferable.

The solvent preferably has an inorganic / organic value (I / O value) of 0.5 or more and a solubility parameter in the range of 16 to 40 [mJ / m ³ ] ^1/2 . More preferably, the I / O value is 0.6 to 10 and the solubility parameter is in the range of 18 to 31 [mJ / m ³ ] ^1/2 . If the I / O value is less than or equal to the upper limit value (the inorganicity is not too strong) and the solubility parameter is greater than or equal to the lower limit value, the alkali saponification rate decreases or the overall uniformity of the saponification degree is unsatisfactory. This is preferable because there is no inconvenience. On the other hand, if the I / O value is equal to or higher than the lower limit value (not too biased toward the organic side) and the solubility parameter is equal to or lower than the upper limit value, inconveniences such as a high saponification rate and easy haze formation may occur. This is preferable because it is excellent in terms of overall uniformity.

  Examples of the organic solvent having preferable characteristic values include those described in “Organic Synthetic Chemistry Association”, “New Edition Solvent Pocket Book” {Om Corp., 1994}. For the inorganic / organic value (I / O value) of the organic solvent, see, for example, Yoshio Tanaka “Organic Conceptual Diagram” (Sankyo Publishing Co., Ltd., 1983) p. 1-31.

  Specifically, monohydric aliphatic alcohols (for example, methanol, ethanol, propanol, butanol, pentanol, hexanol, etc.), alicyclic alkanols (for example, cyclohexanol, methylcyclohexanol, methoxycyclohexanol, cyclohexyl methanol, Cyclohexylethanol, cyclohexylpropanol, etc.), phenylalkanols (eg, benzyl alcohol, phenylethanol, phenylpropanol, phenoxyethanol, methoxybenzyl alcohol, benzyloxyethanol, etc.), heterocyclic alkanols (eg, furfuryl alcohol, tetrahydrofurfur) Furyl alcohol, etc.), monoethers of glycol compounds (eg, methyl cellosolve, ethyl cellosolve, propyl cell) Rub, methoxymethoxyethanol, butyl cellosolve, hexyl cellosolve, methyl carbitol, ethyl carbitol, propyl carbitol, butyl carbitol, ethoxy triglycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether Etc.) Ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), Amides (eg, N, N-dimethylformamide, dimethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, etc.) , Sulfoxides (eg, dimethyl sulfoxide) and ethers (eg, tetrahydrofuran, pyran, dioxane, trioxane, dimethyl cellosolve, diethyl) Cellosolve, dipropyl cellosolve, methyl ethyl cellosolve, dimethyl carbitol, dimethyl carbitol, methyl ethyl carbitol, etc.) and the like. The organic solvent to be used may be used alone or in combination of two or more.

  When organic solvents are used alone or in combination of two or more, at least one organic solvent is preferably one having high solubility in water. The solubility of the organic solvent in water is preferably 50% by mass or more, and more preferably freely mixed with water. Thus, an alkaline solution having sufficient solubility in an alkali agent, a salt of a fatty acid by-produced by carrying out saponification, a carbonate salt generated by absorbing carbon dioxide in the air, and the like can be prepared.

The use ratio of the organic solvent in the solvent is determined according to the type of solvent, miscibility with water (solubility), reaction temperature and reaction time.
The mixing ratio of water and organic solvent is preferably 3/97 to 85/15 mass ratio. More preferably, it is 5 / 95-60 / 40 mass ratio, More preferably, it is 15 / 85-40 / 60 mass ratio. Within this range, the entire film surface can be easily saponified uniformly without impairing the optical properties of the acylate film.

  As the alkaline solution used in the present invention, the alkaline agent is an alkali metal hydroxide, the solvent of the alkaline solution is an alcohol having 8 or less carbon atoms, a ketone having 6 or less carbon atoms, and the number of carbon atoms. It is particularly preferable to include one or more organic solvents selected from esters of 6 or less and polyhydric alcohols having 6 or less carbon atoms and water. Metal hydroxides are preferred because they are highly reactive with polymer films and can reduce the amount of alkaline agent used. The combination of the organic solvent and water is preferable because the solubility of the metal hydroxide is high.

  The alkaline solution used in the present invention is preferably adjusted so as to fall within the range of the liquid physical properties described below. The alkaline solution preferably has a surface tension of 45 mN / m or less at 35 ° C. and a viscosity of 0.8 to 20 mPa · s at 35 ° C. More preferably, the surface tension is 20 to 40 mN / m and the viscosity is 1 to 15 mPa · s. Within this range, the application of the alkaline solution can be easily performed in a stable manner according to the conveying speed, and the wettability of the liquid on the film surface, the retention of the solution applied on the film surface, the film after saponification The removability of the alkaline liquid from the surface is sufficient.

  As the organic solvent contained in the alkaline solution used in the present invention, an organic solvent (for example, fluorinated alcohol) different from the organic solvent having the above-mentioned preferable I / O value is used as a dissolution aid for the surfactant and compatibilizer described later. You may use together as an agent. The content is preferably 0.1 to 5% with respect to the total mass of the liquid contained in the alkaline solution.

  In addition, when an organic solvent, particularly an organic solvent in each of the above-mentioned organic and soluble ranges, is used in combination with water, a surfactant, a compatibilizing agent, etc. described later, a high saponification rate is maintained and the entire surface is covered. The uniformity of the saponification degree is improved. That is, the alkaline solution is preferably an alkaline solution containing a water-soluble organic solvent having a boiling point of 60 to 120 ° C., a surfactant and a compatibilizing agent.

(Surfactant)
The alkaline solution used in the present invention preferably contains a surfactant. By adding a surfactant, the surface tension is lowered to facilitate coating, the uniformity of the coating is increased to prevent repelling failure, and haze that is likely to occur in the presence of an organic solvent is suppressed. Has the advantage that the saponification reaction proceeds uniformly. The effect becomes particularly remarkable by the coexistence of a compatibilizer described later. There is no restriction | limiting in particular in surfactant used, Any of anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, a fluorochemical surfactant, etc. may be sufficient. That is, the alkaline solution preferably contains at least one selected from a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant. In particular, nonionic surfactants are preferred.

  Specifically, for example, Tokiyuki Yoshida “Surfactant Handbook (new edition)” (Engineering Books, published in 1987), “Functional Creation / Material Development / Applied Technology of Surfactant”, Volume 1 (Technical Education Publishing) , Published in 2000) and the like.

  As the cationic surfactant, quaternary ammonium salts are preferable. As the amphoteric surfactant, betaine-type compounds are preferable. Hereinafter, the nonionic surfactant will be described.

(Nonionic surfactant)
Nonionic surfactants include, for example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, Sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, Polyglycerol fatty acid partial esters, polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, Fatty acid diethanol amides, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxides and the like.

  Specific examples thereof include, for example, polyethylene glycol, polyoxyethylene lauryl ether, polyoxyethylene nonyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene behenyl ether, polyoxyethylene Oxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene behenyl ether, polyoxyethylene phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene stearamide, polyoxy Ethylene oleamide, polyoxyethylene castor oil, polyoxyethylene ethylene abietic Ether, polyoxyethylene nonine ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene glyceryl monooleate, polyoxyethylene glyceryl monostearate, polyoxyethylene propylene glycol monostearate, oxyethyleneoxy Propylene block polymer, distyrenated phenol polyethylene oxide adduct, tribenzylphenol polyethylene oxide adduct, octylphenol polyoxyethylene polyoxypropylene adduct, glycerol monostearate, sorbitan monolaurate, polyoxyethylene sorbitan monolaurate, etc. It is done. These nonionic surfactants preferably have a mass average molecular weight of 300 to 50,000, particularly preferably 500 to 5,000.

Among these, polyethylene oxide derivatives such as various polyalkylene glycol derivatives and various polyethylene oxide adducts are preferable.
In the present invention, it is particularly preferable that the surfactant is a nonionic surfactant represented by the following general formula (1).
General formula (1): R1-L1-Q1
In the formula, R1 represents an alkyl group having 8 or more carbon atoms (single or modified), L1 represents a group linking R1 and Q1, represents a direct bond or a divalent linking group, and Q ¹ represents a polyvalent group. It represents a nonionic hydrophilic group selected from an oxyethylene unit (polymerization degree of 5 to 150), a polyglycerin unit (polymerization degree of 3 to 30), and a hydrophilic sugar chain unit.
Specific examples of such nonionic surfactants include, for example, polyoxyethylene lauryl ether, polyoxyethylene nonyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene behenyl ether , Polyoxyethylene octyl phenyl ether, polyoxyethylene stearylamine, polyoxyethylene oleylamine, and the like. These nonionic surfactants preferably have a mass average molecular weight of 300 to 50,000, particularly preferably 500 to 5,000.

Moreover, in this invention, it is also a preferable aspect to use the compound represented by following General formula (2) as said nonionic surfactant.
General formula (2):
R ¹¹ −O (CH ₂ CHR ¹² O) _l − (CH ₂ CHR ¹³ O) _m − (CH ₂ CHR ¹⁴ O) _n −R ¹⁵
In the general formula (2), R ^{11 to} R ¹⁵ each represent a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group, an alkynyl group, an aryl group, a carbonyl group, a carboxylate group, a sulfonyl group, or a sulfonate group. To express.
Specific examples of the alkyl group include a methyl group, an ethyl group, and a hexyl group. Specific examples of the alkenyl group include a vinyl group and a propenyl group. Specific examples of the alkynyl group include An acetyl group, a propynyl group, etc. are mentioned, As a specific example of the said aryl group, a phenyl group, 4-hydroxyphenyl group, etc. are mentioned.
l, m, and n represent an integer of 0 or more. However, all of l, m, and n are not 0.
Specific examples of the compound represented by the general formula (2) include homopolymers such as polyethylene glycol and polypropylene glycol, copolymers of ethylene glycol and propylene glycol, and the like. The ratio of the copolymer is preferably 10/90 to 90/10 from the viewpoint of solubility in an alkaline aqueous solution. Of the copolymers, graft polymers and block polymers are preferred from the viewpoints of solubility in an alkaline saponification solution and ease of alkaline saponification treatment.

  In the alkaline solution, it is preferable to use a nonionic surfactant and an anionic surfactant or a nonionic surfactant and a cationic surfactant in coexistence because the effect of the present invention is enhanced. The amount of these surfactants to be added to the alkaline solution is preferably 0.001 to 10% by mass, more preferably 0.01 to 10% by mass, and still more preferably 0.1 to 10% by mass in the entire solution. The most preferable range is 0.1 to 5% by mass.

(Compatibilizer)
It is also preferable that the alkaline solution used in the present invention contains a compatibilizing agent. In the present invention, the “compatibilizer” refers to a hydrophilic compound having a water solubility of 50 g or more with respect to 100 g of the compatibilizer at a temperature of 25 ° C. The solubility of water in the compatibilizing agent is preferably 80 g or more, more preferably 100 g or more, with respect to 100 g of the compatibilizing agent. When the compatibilizer is a liquid compound, the boiling point is preferably 100 ° C. or higher, and more preferably 120 ° C. or higher.

  The compatibilizing agent has an action of preventing the alkaline solution attached to the wall surface from being dried in a bath or the like for storing the alkaline solution, suppressing the fixation, and stably holding the alkaline solution. Also, after applying the alkali solution to the surface of the optical film and holding it for a certain period of time, until the saponification is stopped, the thin film of the applied alkali solution is dried, resulting in precipitation of solids, and in the water washing step It has the effect of preventing the occurrence of problems such as making it difficult to wash out solid materials. Furthermore, phase separation between water as a solvent and the organic solvent is prevented. In particular, the coexistence of the surfactant, the organic solvent, and the compatibilizer described above allows the processed optical film to have a low haze and to be stably and evenly uniform even when long continuous saponification is performed. A saponification degree is preferable.

  The compatibilizing agent is not particularly limited as long as it is a material that satisfies the above conditions. For example, a water-soluble polymer including a repeating unit having a hydroxyl group and / or an amide group such as a polyol compound or a saccharide is preferably exemplified. .

  As the polyol compound, any of a low molecular compound, an oligomer compound, and a polymer compound can be used.

  Examples of aliphatic polyols include alkanediols having 2 to 8 carbon atoms (for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol monomethyl ether, glycerol monoethyl ether, cyclohexanediol, cyclohexanedimethanol). , Diethylene glycol, dipropylene glycol, etc.), C3-C18 alkanes containing 3 or more hydroxyl groups (for example, glycerin, trimethylolethane, trimethylolpropane, trimethylolbutane, hexanetriol, pentaerythritol, diglycerin) , Dipentaerythritol, inositol, etc.).

  As the polyalkyleneoxy polyols, the same alkylene diols as described above may be bonded to each other, or different alkylene diols may be bonded to each other, but a polyalkylene polyol in which the same alkylene diols are bonded to each other is more preferable. . In any case, the number of bonds is preferably 3 to 100, more preferably 3 to 50. Specific examples include polyethylene glycol, polypropylene glycol, and poly (oxyethylene-oxypropylene).

  Examples of sugars include “Natural Polymers” Chapter 2 {Kyoritsu Shuppan Co., Ltd., published in 1984} edited by the Society of Polymer Science, Japan, “Modern Industrial Chemistry 22, Natural Products Industrial Chemistry” II "{Asakura Shoten Co., Ltd., published in 1967} and the like. Among them, saccharides that do not have a free aldehyde group and a ketone group and do not exhibit reducibility are preferable.

Sugars are generally classified into glucose, sucrose, trehalose-type oligosaccharides in which reducing groups are bonded, glycosides in which reducing groups of sugars and non-saccharides are bonded, and sugar alcohols reduced by hydrogenation of saccharides. Both are suitably used in the present invention.
For example, saccharose, trehalose, alkyl glycoside, phenol glycoside, mustard oil glycoside, D, L-arabit, rebit, xylit, D, L-sorbit, D, L-mannit, D, L-exit , D, L-Tallit, Zulsicit, Allozulcit, and reduced water candy. These saccharides can be used alone or in combination of two or more.

Examples of the water-soluble polymer having a repeating unit having a hydroxyl group and / or an amide group include natural gums (for example, gum arabic, guar gum, tragand gum, etc.), polyvinylpyrrolidone, dihydroxypropyl acrylate polymer, celluloses or chitosan. And an addition reaction product of an epoxy compound (ethylene oxide or propylene oxide).
Of these, polyol compounds such as alkylene polyols, polyalkyleneoxy polyols and sugar alcohols are preferred.

  The content of the compatibilizing agent is preferably 0.5 to 25% by mass and more preferably 1 to 20% by mass in the entire alkali solution.

The alkaline solution used in the present invention can contain other additives. Examples of other additives include known additives such as antifoaming agents, alkaline solution stabilizers, pH buffering agents, preservatives, and antibacterial agents.
The content of the other additives is preferably 0.001 to 30% by mass, and more preferably 0.005 to 25% by mass in the entire alkaline solution.

[Application method in the process of applying an alkaline solution to a polymer film]
As described above, the alkali saponification of the polymer film using the alkali solution is preferably carried out by a coating method capable of treating only one surface of the film. As coating methods, dip coating method, curtain coating method, bar coating method, rod coating method (rod wrapped with a thin metal wire), roll coating method (forward roll coater, reverse roll coater, gravure coater), curtain coating method And a coating method such as a die coating method (extrusion coater (slot coater), slide coater, slit die coater). Regarding the coating method, various documents {e.g., "Modern Coating and Drying Technology", E.I. Cohen and E.M. B. Edited by Gutoff, VCH Publishers, Inc. (1992)}. The amount of the alkaline solution applied is desirably 1 to 50 mL / m ² , more preferably 5 to 30 mL / m ² , and it is desirable to suppress it as much as possible in view of waste liquid treatment for removal by washing with water.
It is preferable to use a coating means such as a rod coater, gravure coater, blade coater or die coater that can be stably operated even in a small coating amount range. In particular, a die coater that can be applied at a high speed without causing uneven coating stripes in a small coating amount region and is a non-contact method between the coating device and the surface on which the coating solution is applied is preferable.

[Washing]
After the saponification reaction, as will be described later, a washing process using a roll coater or a bar coater (the washing process is a dilution for washing off an alkaline solution that could not be removed by dilution (neutralization) washing or dilution (neutralization)). After the saponification reaction, the alkaline solution and the saponification treatment reaction product can be removed from the film surface by washing with water, neutralizing and washing with water. Specifically, for example, the contents described in International Publication No. 02/46809 pamphlet and the like can be mentioned.

[Step of diluting (neutralizing) the alkaline solution present on the polymer film with water or an alkaline diluent containing water and an organic solvent]
In order to dilute the applied alkaline solution, a method of applying an alkaline diluent can be employed. This method is a preferable method when the polymer film is continuously conveyed. The method of applying the alkali diluent is a more preferable method because it can be carried out using the minimum amount of alkali diluent.
In the present invention, for the purpose of diluting the alkaline solution, water or an alkaline diluent containing water and an organic solvent is used for the purpose of reducing the alkali concentration described below. Moreover, it is also possible to use the acid solution (after-mentioned) for the purpose of reducing pH instead of these alkali dilution liquids.

(Water or alkaline dilution containing water and organic solvent)
The purpose of the alkali dilution solution is to lower the alkali concentration, so it must be a solvent that dissolves the alkali agent in the alkali solution. Therefore, water or a mixed solution of an organic solvent and water is used. At this time, two or more organic solvents may be mixed and used. The organic solvent used for the alkaline solution described above can be used advantageously. As the alkali dilution liquid, it is preferable to use water and a solvent composed of one or more compounds selected from monovalent or polyhydric alcohols having 1 to 4 carbon atoms, ketones, and carboxylic acids. A compound having 5 or more carbon atoms may cause phase separation with water, and may be poorly washed in the water washing step described later, and may cause failure in the produced polymer film or an optical film using the same, It is not preferable.
Hereinafter, “water or an alkali diluent containing water and an organic solvent” is also referred to as “alkali diluent”.

(Applying water or an alkaline diluent containing water and organic solvent)
It is desirable that the application of the alkali dilution liquid is a system capable of continuous application in which the alkali dilution liquid can be applied again onto the polymer film on which the alkali solution has already been applied. For the application, the same roll coater (forward roll coater, reverse roll coater, gravure coater) and rod coater as described in the application step of the alkaline solution are used. In order to reduce the alkali concentration by quickly mixing the alkali solution and the alkali diluent present on the polymer film, the flow is in a minute region (sometimes called a coating bead) where the alkali diluent is applied. This is because a roll coater or a rod coater in which the flow is not uniform is more suitable than a die coater that is a laminar flow. By using these coaters, the amount of liquid present on the film surface can be reduced while diluting an alkaline solution. Can be reduced. By diluting the alkaline solution and reducing the amount of the liquid present on the film surface, the alkali saponification treatment can be performed while minimizing the influence on the optical properties.

Hereinafter, the upstream side in the film conveyance direction with respect to the coater is referred to as primary, and the downstream side is referred to as secondary.
The supply amount of the alkali dilution liquid to the primary side of the coater used for the application of the alkali dilution liquid (that is, the side where the alkali solution after the saponification reaction enters the coater) is the concentration of the alkali solution and the application of the alkali dilution liquid. Decide according to the speed. In the case of a roll coater or a rod coater, since the flow in the coating bead is not uniform, mixing of the alkali solution and the alkali diluted solution occurs, and this mixed solution is re-coated on the secondary side of the coater. Therefore, in this case, since the dilution rate cannot be specified by the supply amount of the alkali diluent, it is necessary to measure the alkali concentration after application of the alkali diluent. Also in the roll coater and the rod coater, the supply amount is preferably an amount that dilutes the original alkali concentration 1.5 to 10 times, and more preferably an amount that dilutes 2 to 5 times.
The alkali dilution liquid preferably has a surface tension of not more than 75 mN / m at 35 ° C., more preferably 35 to 60 mN / m. If the surface tension is within this range, the surface of the polymer film coated with the alkaline solution tends to wet and spread, and the coated bead is stabilized. When the surface tension of the diluting liquid is higher than 75 mN / m, the coating bead becomes unstable (causes the liquid to run out in some cases), and causes optical failure (unevenness, etc.) in the saponified film and the optical film using it. Sometimes. Also, if it is lower than 35 mN / m, the hydrophobic component contained in the polymer film is extracted from the polymer film with a diluting solution and adhered to the surface, causing optical failure (such as blisters) in the saponified film or the optical film having it. There is.

(Acid solution)
An acid solution can also be used to quickly stop the saponification reaction with alkali. In order to neutralize with a small amount, it is preferable to use a strong acid. Furthermore, considering the ease of washing with water, it is preferable to select an acid having a high solubility in water for the salt produced after the neutralization reaction with the alkali. Hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, chromic acid and acetic acid are particularly preferred.

  In order to neutralize the applied alkaline solution with an acid, a method of applying an acid solution can be employed. This method is a preferable method when the polymer film is continuously conveyed. The method of applying an acid solution is a more preferable method because it can be carried out using a minimum amount of acid solution.

  It is desirable that the acid solution is applied in such a manner that the acid solution can be applied again on the polymer film on which the alkaline solution has already been applied. The same applies to the case where it is carried out before dilution with an alkaline diluent. In the case of carrying out after dilution with an alkaline diluent, it is desirable that the coating method be a continuous coating method in which an acid solution can be applied again onto the polymer film after the step of applying an alkaline solution and washing with the alkaline diluent. For coating, the same roll coater (forward roll coater, reverse roll coater, gravure coater) and rod coater (rod wound with a thin metal wire) as described in the coating step are used. In order to reduce the alkali concentration by quickly mixing and neutralizing the alkali solution and the acid solution, the flow is a laminar flow in a small area (sometimes called a coating bead) where the acid solution is applied. This is because a roll coater or a rod coater in which the flow is not uniform is preferable to the coater.

  The coating amount of the acid solution is determined according to the type of alkali and the concentration of the alkali solution. In the case of a roll coater or a rod coater, since the flow in the coating bead is not uniform, mixing of the alkaline solution and the acid solution occurs, and the mixed solution is re-coated on the secondary side of the coater. Therefore, in this case, since the neutralization rate cannot be specified by the amount of the acid solution applied, it is necessary to measure the alkali concentration after application of the acid solution. In a roll coater or a rod coater, the coating amount of the acid solution is preferably determined such that the pH after application of the acid solution is 4 to 9, and more preferably 6 to 8.

The alkali diluted solution (or acid solution) is mixed with the alkali solution present on the polymer film as described above, and the mixed solution is reapplied on the film surface on the secondary side of the coater. That is, the diluted cleaning step is suitably performed by reducing the amount of liquid that is diluted (or neutralized) and reapplied. The amount of the diluted alkali mixed solution reapplied on the polymer film after dilution washing is preferably 4 mL / m ² or less, more preferably 3 mL / m ² or less, still more preferably 1.5 mL / m. ² or less. Furthermore, when the dilution washing process is performed with two or more coaters as will be described later, it is preferably the amount of re-coating in the first coater (first coater in the dilution washing process).
By making the amount of liquid reapplied on the film surface of the coater secondary side within the above range, the surface saponified during the washing process is prevented from being (partially) dried. It is possible to prevent planar failures that occur due to dry conditions.

  The temperature of the polymer film can be lowered to stop the saponification reaction. In order to promote the reaction, the saponification reaction is substantially stopped by sufficiently lowering the temperature from a state maintained at room temperature or higher. The means for lowering the temperature of the polymer film is determined taking into consideration that one side of the polymer film is wet. Collision of cold air with the opposite surface of the coating or contact heat transfer with a cooling roll can be preferably employed. The film temperature after cooling is preferably 5 ° C to 60 ° C, more preferably 10 ° C to 50 ° C, and most preferably 15 ° C to 30 ° C. The film temperature is preferably measured with a non-contact infrared thermometer. Feedback control can be performed on the cooling means to adjust the cooling temperature.

[Process of washing off alkaline solution from polymer film (washing process after dilution)]
In the present invention, after the dilution cleaning step, it is preferable to perform a step of washing off the alkaline solution that could not be removed by the dilution cleaning from the polymer film.
A post-dilution washing step is performed to remove the alkaline solution. If the alkaline solution remains, not only the saponification reaction proceeds, but also affects the alignment film and liquid crystal molecular layer coating applied later and the alignment of the liquid crystal molecules. Cleaning can be performed by a method of applying cleaning water.
In the present invention, cleaning water is applied by a roll coater or a rod coater.

The amount of water used for rinsing is an amount that exceeds the theoretical dilution factor defined below.
Theoretical dilution factor = Amount of washing water used [mL / m ² ] ÷ Amount of alkaline solution applied [mL / m ² ]
That is, a theoretical dilution rate is defined on the assumption that all of the water used for washing contributes to the dilute mixing of the alkaline solution. In practice, since complete mixing does not occur, a washing water amount exceeding the theoretical dilution rate is used. Although depending on the alkali concentration of the alkaline solution used, the secondary additives, and the type of the solvent, washing with water capable of obtaining a theoretical dilution of at least 100 to 1000 times, preferably 500 to 10,000 times, more preferably 1000 to 100,000 times. Use water.

  When performing the washing process with a roll coater or a rod coater, the mixing efficiency of the alkaline solution and the washing water can be increased by making the speed of the outer circumference of the roll or rod different from the conveying speed of the polymer film. The outer peripheral speed with respect to the conveying speed is preferably 1/3 to 3 times, and more preferably 1/2 to 2 times.

  At both ends in the width direction of the polymer film, it often occurs that the application amount of the alkaline solution and the application amount of the acid solution used for neutralization are large. In order to ensure the cleanability of the portion where the coating amount is large, the clearance of the slit from which water is discharged can be set widely so that the flow rate at both ends is increased. In addition, a coater having a narrow width may be separately installed in order to locally supply water films to both ends. Multiple coaters with a narrow width can be installed.

  When a certain amount of water is used in the water washing, a batch type washing method in which the whole amount is applied at once rather than being divided into several times is preferable. That is, the amount of water is divided into several parts and supplied to a plurality of water washing means installed in tandem in the transport direction of the polymer film. By providing a draining means for removing the water film on the polymer film between the washing means and the washing means, the washing dilution efficiency can be further increased. Specific examples of draining means include a rod used for a rod coater and a roll used for a roll coater. It is advantageous that the number of washing means arranged in tandem is large. However, from the viewpoint of installation space and equipment cost, usually 2 to 10 stages, preferably 2 to 5 stages are used.

  The water film thickness after the draining means is preferably thin, but the minimum water film thickness is limited depending on the type of draining means used. In the method of physically contacting a solid with a polymer film such as a rod or roll, even if the solid is an elastic body with low hardness such as rubber, the film surface is scratched or the elastic body is worn away. Therefore, it is necessary to leave a finite water film as the lubricating fluid. Usually, a water film of several μm or more, preferably 10 μm or more is left as a lubricating fluid.

  It is preferable to use pure water as the washing water. The pure water used in the present invention has a specific electric resistance of at least 0.1 MΩ or more, in particular, metal ions such as sodium, potassium, magnesium and calcium are less than 1 ppm, and anions such as chloro and nitric acid are less than 0.1 ppm. Preferably there is. Pure water can be obtained by a simple substance such as a reverse osmosis membrane, an ion exchange resin, distillation, or a combination thereof.

  The higher the washing water temperature, the higher the washing ability. However, in the method of applying water on the polymer film to be transported, the area of water in contact with air is large on the coater and after application, and the higher the temperature, the more the evaporation occurs. Increased risk of condensation. For this reason, the temperature of the washing water is usually set in the range of 5 ° C to 90 ° C, preferably 25 ° C to 80 ° C, more preferably 25 ° C to 60 ° C.

In the present invention, a plurality of coaters can be installed in the cleaning process. For example, in the dilution cleaning step, an acid solution for neutralizing the alkali solution present on the polymer film is supplied / provided to the polymer film coated with the alkali solution by a rod coater for applying the first alkali dilution solution. Water and organics to reduce the amount of liquid on the polymer film on the secondary side of the coater while neutralizing, and further to wash hydrophobic contaminants on the surface of the polymer film with the rod coater for the second dilution. An embodiment in which a diluent containing a solvent is supplied / diluted can be mentioned.
In the washing step, the number of coaters to be continuously placed in the transport direction of the polymer film is preferably 2 or more, more preferably 2 to 10, and further preferably 3 to 6.

  A drying step can also be performed after the washing step. Before the polymer film is wound into a roll, it may be dried by heating in order to adjust the water content to a preferable level. Conversely, the humidity can be adjusted with a wind having a set humidity. The temperature of the drying air is preferably 30 to 200 ° C, more preferably 40 to 150 ° C, and particularly preferably 50 to 120 ° C.

Moreover, it is preferable to implement each process mentioned above, conveying a polymer film, and it is further preferable to implement each process continuously, conveying a polymer film.
The surface saponified cellulose acylate film of the present invention can be obtained by performing an alkali saponification treatment as described above.

[Film surface properties after saponification]
(Change in the amount of phosphorus element in the width direction)
The amount of change when the amount of phosphorus element in the width direction of the polymer film surface after the saponification treatment by the alkali saponification method is measured by ESCA is preferably smaller than 0.005. More preferably, the amount of change in the width direction is smaller than 0.004. The reason is uncertain, but a plasticizer having phosphorus as a film component may change the optical properties of the optical compensation film. Therefore, when the amount of change in phosphorus is small, it is estimated that unevenness is reduced.
The amount of change was measured by sampling 9 points in the width direction relative to the saponification direction of the polymer film, and using a photoelectron spectrometer {“ESCA750” type, manufactured by Shimadzu Corporation), the carbon atoms and phosphorus on the surface of the saponified film. The atomic weight was measured as a peak value with respect to the reference lines of C1s and P2p, respectively, and the area ratio was calculated as a P amount (P / C). The difference between the maximum value and the minimum value was defined as the amount of change in the width direction of the phosphorus element amount.

<Optical compensation sheet>
The polymer film saponified by the alkali saponification method of the polymer film of the present invention is formed with an alignment film thereon, and then liquid crystal molecules are applied on the alignment film, and the alignment of the liquid crystal molecules is fixed and the optical film is different. An optical compensation sheet can be produced by forming the isotropic layer. Hereinafter, the optical compensation sheet and its constituent layers will be described.
[Alignment film]
The alignment film is preferably formed by coating an alkali saponified polymer film on the transparent support as a transparent support. A cured polymer film is preferred from the viewpoint of the strength of the alignment film itself and the adhesion to the transparent support or the upper optically anisotropic layer. The alignment film is provided in order to define the alignment direction of the liquid crystal compound provided thereon. Examples of the orientation regulating method include conventionally known rubbing, application of a magnetic field or electric field, and light irradiation.

The alignment film used in the present invention can correspond to the type of display mode of the liquid crystal cell.
In a display mode (for example, VA, OCB, HAN) in which many rod-like liquid crystal molecules in the liquid crystal cell are aligned substantially vertically, the liquid crystal molecules in the optically anisotropic layer are aligned substantially horizontally. It has a function. In a display mode (for example, STN) in which many rod-like liquid crystal molecules in the liquid crystal cell are substantially horizontally aligned, the liquid crystal molecules in the optically anisotropic layer have a function of being substantially vertically aligned. In the display mode (for example, TN) in which many rod-like liquid crystal molecules in the liquid crystal cell are substantially obliquely aligned, the liquid crystal molecules of the optically anisotropic layer have a function of being substantially obliquely aligned.

Specific types of polymers used in the alignment film in the present invention are described in the literature on optical compensation sheets using discotic liquid crystalline molecules corresponding to the various display modes described above.
As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include compounds described in paragraph No. [0022] of JP-A-8-338913. Preferable examples include water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol). Among these, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol. Polyvinyl alcohol is most preferred.

  The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%, and most preferably 85 to 95%. The degree of polymerization of polyvinyl alcohol is preferably 100 to 3000.

  The modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. Specific examples of these modified polyvinyl alcohol compounds include, for example, paragraph numbers [0074] of JP-A No. 2000-56310, paragraph numbers [0022] to [0145] of JP-A No. 2000-155216, and paragraph numbers of JP-A No. 2002-62426. Those described in [0018] to [0022].

  Moreover, when aligning by light irradiation, it has the photo-alignment group which expresses a photo-alignment function in a molecule | numerator. Examples of these photo-alignment groups include those described in “Liquid Crystal, Vol. 3 (1) 3-16 (1999)” written by Masaki Hasegawa, and have a photo-alignment function by a photodimerization reaction having a C═C bond. Photo-alignment group (for example, polyene group, stilbene group, stilbazole group, stilbazolium group, cinnamoyl group, hemithioindigo group, chalcone group, etc.), photo-alignment function that exhibits photo-alignment function by photodimerization reaction with C = O bond Group (for example, a group having a structure such as a benzophenone group or a coumarin group). Specific examples include those described in paragraphs [0021] and the like of JP-A Nos. 2000-122069 and 2002-317013.

  Examples of cross-linking agents for polymers (preferably water-soluble polymers, more preferably polyvinyl alcohol or modified polyvinyl alcohol) used in the alignment film include aldehydes, N-methylol compounds, dioxane derivatives, and carboxyl groups by activating them. Compounds that act, active vinyl compounds, active halogen compounds, isoxazoles and dialdehyde starches are included. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraph numbers [0023] to [0024] of JP-A-2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  The addition amount of the crosslinking agent is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass with respect to the polymer. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. If the crosslinking agent remains in the alignment film in an amount exceeding 1.0% by mass, sufficient durability cannot be obtained. When such an alignment film is used in a liquid crystal display device, reticulation may occur when used for a long time or when left in a high temperature and high humidity atmosphere for a long time.

[Carboxylic acid compound contained in alignment film]
The alignment film-forming composition in the present invention preferably contains a specific carboxylic acid compound.
As a result, the coated surface of the optical compensation sheet obtained by applying an optically anisotropic layer after aligning the obtained alignment film by an aligning means is good and reduces or eliminates optical defects such as white spots. The improvement effect is expressed. The presumed reason is that the specific carboxylic acid compound contained in the alignment film has less influence on the alignment state of liquid crystal molecules when the surface of the alignment film is stabilized and the optically anisotropic layer is coated. This seems to be one factor. In addition, when the surface of the transparent support is hydrophilized by alkali saponification treatment, it is considered that an alignment film having good optical performance is stably formed even if there is a slight remaining treatment liquid on the film surface. . Naturally, the effect varies depending on the amount added, so the timely amount needs to be adjusted.

Specific carboxylic acid compounds include carboxylic acids containing at least one hydrogen atom-containing polar group having hydrogen bonding properties. These carboxylic acids may be any of aliphatic compounds, aromatic compounds, or heterocyclic compounds.
Specific polar groups include —OH, —SH, —NHR, —CONHR, —SO ₂ NHR, —HNCONHR, —NHSO ₂ NHR, —NHCOR ¹ , —NHSO ₂ R ¹ . However, R represents a hydrogen atom, an aliphatic group, an aryl group, or a heterocyclic group. R ¹ represents an aliphatic group, an aryl group, or a heterocyclic group. When the carboxylic acid contains a plurality of the above polar groups, the polar groups may be the same or different.

Preferred specific polar groups in the present invention include —OH, —SH, —NHR, —CONH ₂ , —SO ₂ NH ₂ , —HNCONHR, —NHSO ₂ NHR, and —NHSO ₂ R ¹ .
Here, R represents a hydrogen atom, an aliphatic group, an aryl group, or a heterocyclic group. R ¹ represents an aliphatic group, an aryl group, or a heterocyclic group.

When R represents an aliphatic group, the aliphatic group is a linear or branched alkyl group having 1 to 22 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group). Group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nanodecyl group, eicosanyl group, heneicosanyl group, docosanyl group), carbon A linear or branched alkenyl group having 2 to 22 (for example, vinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, octenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, hexadecenyl group, octadecenyl group, Eicosenyl group, dococenyl group, butadienyl group, pentadie Group, hexadienyl group, octadienyl group, etc.), linear or branched alkynyl group having 2 to 22 carbon atoms (for example, ethynyl group, propynyl group, butynyl group, hexynyl group, octanyl group, decanyl group, dodecanyl group, etc.) ), An alicyclic hydrocarbon group having 5 to 22 carbon atoms (for example, cyclopentane, cyclopentene, cyclopentadiene, cyclohexane, cyclohexene, cyclohexadiene, cycloheptane, cycloheptene, cycloheptadiene, cyclooctane, cyclooctene, cyclooctane Diene, decalin, etc.).
Among these, a linear aliphatic group having 1 to 18 carbon atoms and a branched aliphatic group having 3 to 18 carbon atoms are more preferable.

The aryl group represents an aryl group having 6 to 18 carbon atoms (as the aryl ring, benzene, naphthalene, dihydronaphthalene, biphenylene, etc.).
As the heterocyclic group, a heterocyclic group having a monocyclic or polycyclic ring structure containing at least one of an oxygen atom, a sulfur atom and a nitrogen atom (for example, a furanyl group, Tetrahydrofuranyl group, pyranyl group, pyroyl group, pyridyl group, pyrazinyl group, morpholinyl group, thienyl group, benzothienyl group, etc.).

The above aliphatic group, aryl group, and heterocyclic group may each have a substituent, and as the substituent that can be introduced, a monovalent nonmetallic atomic group excluding hydrogen is used.
Specific examples of the nonmetallic atomic group include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, nitro group, —OR ¹¹ , —SR ¹¹ , —COR ¹¹ , —COOR ¹¹ , —OCOR ¹¹ , —SO ₂ R ¹¹ , —NHCONHR ¹¹ , —N (R ¹² ) COR ¹¹ , —N (R ¹² ) SO ₂ R ¹¹ , —N (R ¹³ ) (R ¹⁴ ), —CON (R ¹³ ) (R ¹⁴ ), —SO ₂ N (R ¹³ ) (R ¹⁴ ), —P (═O) (R ¹⁵ ) (R ¹⁶ ), —OP (═O) (R ¹⁵ ) (R ¹⁶ ), — Si (R ¹⁷ ) (R ¹⁸ ) (R ¹⁹ ), an aliphatic group having 1 to 22 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a heterocyclic group. These aliphatic group, aryl group and heterocyclic group have the same meanings as those for R.

R ¹¹ represents an aliphatic group having 1 to 22 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a heterocyclic group. The aliphatic group for R ¹¹ has the same meaning as the aliphatic group represented by R. Examples of the aryl group for R ¹¹ include the same aryl groups represented by R. Such an aryl group may further have a substituent, and the substituent is the same as that exemplified as the substituent that can be introduced into the aliphatic group, aryl group, and heterocyclic group represented by R. Can be mentioned. The heterocyclic group in R ¹¹ has the same meaning as the heterocyclic group represented by R.
R ¹² represents the same as the hydrogen atom or R ¹¹ group.
R ¹³ and R ¹⁴ each independently represents a hydrogen atom or the same as R ^11, and R ¹³ and R ¹⁴ are bonded to each other to form a 5-membered or 6-membered ring containing an N atom. It may be formed.

R ¹⁵ and R ¹⁶ each independently represents an aliphatic group having 1 to 22 carbon atoms, an aryl group having 6 to 14 carbon atoms, or —OR ¹¹ . The aliphatic group for R ¹⁵ and R ¹⁶ has the same meaning as the aliphatic group represented by R. Examples of the aryl group for R ¹⁵ and R ¹⁶ include the same aryl groups as those represented by R. Such an aryl group may further have a substituent, and the substituent is the same as those exemplified as the substituent that can be introduced into the aliphatic group, aryl group, and heterocyclic group represented by R. Things.

R ¹⁷ , R ¹⁸ and R ¹⁹ each independently represents a hydrocarbon group having 1 to 22 carbon atoms or —OR ^20, and at least one of these substituents represents a hydrocarbon group. The hydrocarbon group represents the same aliphatic group and aryl group represented by R, and —OR ²⁰ represents the same contents as —OR ¹¹ .
The aliphatic group, aryl group and heterocyclic group in R ¹ are the same as R.

  Specific carboxylic acid compounds in the present invention include aliphatic carboxylic acids having 1 to 22 carbon atoms (excluding carbon atoms of carboxylic acids), aromatic carboxylic acids having 6 to 14 carbon atoms, and carboxylic acid compounds having heterocyclic carboxylic acids. Particularly preferred are those having a pKa of 6.5 or less. More preferably, the carboxylic acid has a pKa of 3.0 to 6.5.

  Specific examples of these specific carboxylic acid compounds include oxyacids (for example, glycolic acid, lactic acid, glyceric acid, α-oxyalkanoic acids (alkanes having 3 to 18 carbon atoms), etc.), amino acids, α-oxy-β-amino acid, α-oxy-γ-amino acid, β-oxy-α-amino acid, compounds in which the hydroxyl group of these oxyacids or oxyamino acids is derived from an alkoxy group, hydroxycyclohexanecarboxylic acids, hydroxy At least one hydroxyl group of a benzenecarboxylic acid or a polyol (eg, alkanediol, glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, cyclohexanediol, etc.) is converted into a cyclic carboxylic acid anhydride (succinic acid, maleic acid, glutaric acid) , Adipic acid, cyclo Compounds esterified with xanthodicarboxylic acid, anhydrides such as phthalic acid), polyamino compounds (eg, alkylenediamine, diethylenetriamine, triethylenetetramine, cyclohexanediamine, phenylenediamine, etc.) and compounds amidated with cyclic carboxylic acid anhydrides In the present invention, the compounds are not limited to these.

More preferred is a carboxylic acid compound which is a polycarboxylic acid containing at least one hydroxyl group and in which at least one carboxyl group is esterified.
Examples of the polycarboxylic acid containing at least one hydroxyl group include tartronic acid, malic acid, tartaric acid, citric acid, oxyglutamic acid (β-form, γ-form), and at least two hydroxyl groups of the above-mentioned polyol. Examples thereof include compounds esterified with an acid anhydride.

At least one carboxylic acid of these polycarboxylic acid compounds is preferably ester-substituted with a hydrocarbon group having 1 to 22 carbon atoms.
Specific embodiments of the hydrocarbon group having 1 to 22 carbon atoms to be ester-substituted are synonymous with the aliphatic group, aryl group, and heterocyclic group described in R above. These hydrocarbon groups may be substituted, and examples of the substituent include those having the same contents when substituted with R.

It is preferable to add the specific carboxylic acid compound in this invention in the ratio of 0.01-1.0 mass% in the composition for alignment film formation. Furthermore, 0.02-0.5 mass% is preferable.
In this range, an optical compensation sheet free from optical defects such as white spots in which the film strength is sufficiently maintained can be obtained. Furthermore, even if a long film is continuously manufactured, it can be manufactured with extremely stable performance.
That is, the composition for forming an alignment film preferably contains a carboxylic acid compound containing at least one hydrogen atom-containing polar group having hydrogen bonding properties.

  The alignment film is basically formed by applying a coating solution containing the polymer, a crosslinking agent and a specific carboxylic acid, which is a composition for forming an alignment film, onto a transparent support, followed by drying by heating (crosslinking), and an alignment treatment. This is a cured film that can be formed. That is, the alignment film is preferably a cured film obtained by applying an alignment film forming composition containing polyvinyl alcohol and / or modified polyvinyl alcohol as a main component and drying it. The crosslinking reaction may be carried out at any time after coating on the transparent support.

  When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming composition, the coating solution should be a mixed solvent of an organic solvent (eg, methanol, ethanol, isopropanol, etc.) having a defoaming action and water. preferable. The ratio of water: organic solvent (eg, methanol) is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9 in terms of mass ratio. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an orientation film and also an optically anisotropic layer reduces remarkably.

  The coating method of the alignment film is preferably a spin coating method, dip coating method, curtain coating method, die coating method (extrusion coating method, slide coating method, slit coating method), rod coating method or roll coating method. In particular, a rod coating method and a die coating method are preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes.

  Further, when the coating liquid for the optically anisotropic layer is applied after the coating liquid containing the composition for forming the alignment film is applied to the support, dried, and aligned by the aligning means, the surface of the alignment film Is preferably maintained in the range of pH 2.0 to 6.9. Furthermore, pH 2.5-5.0 is more preferable.

Further, when applying the coating liquid for the optically anisotropic layer, it is preferable that the fluctuation range ΔpH of the pH of the alignment film surface in the coating width direction is within a range of ± 0.30. More preferably, ΔpH is in the range of ± 0.15.
An optical compensation sheet coated with an optically anisotropic layer in this range is preferable because optical defects are remarkably reduced.

The method for measuring the pH value of the alignment film surface is to leave the sample coated with the alignment film in an environment of (temperature 25 ° C./humidity 65% RH) for 1 day, and then place 10 ml of pure water in a nitrogen atmosphere. Immediately read the pH value with a pH meter.
The specification of the pH value of the alignment film surface of the present invention and the control of the ΔpH in the coating width direction can be achieved by coating by the rod coating method described above. Furthermore, it is also effective to adjust the drying temperature of the film surface, the air volume when using the drying air, the wind direction, and the like.

The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.

In the case of photo-alignment by light irradiation, the light source as the light irradiation device can be an ultra-high pressure mercury lamp, xenon lamp, fluorescent lamp, laser, etc. Are combined with a polarizer (through the polarizer) to convert the ultraviolet light into linearly polarized light and irradiate the photo-alignment film. As a polarizer, stretch dyed PVA is mainly used. As this linearly polarized ultraviolet irradiation device, for example, the one disclosed in JP-A-10-90684 can be used.
The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 1 μm.

<Optically anisotropic layer>
Next, an optical compensation sheet can be produced by applying liquid crystalline molecules on the formed alignment film and fixing the alignment of the liquid crystalline molecules to form an optically anisotropic layer.
As the liquid crystal molecule, a rod-like liquid crystal molecule or a discotic liquid crystal molecule is preferable, and a discotic liquid crystal molecule is particularly preferable.
Listed below are liquid crystal compounds used as liquid crystal molecules.
As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. These low-molecular liquid crystalline molecules preferably have a polymerizable group in the molecule (for example, described in paragraph No. [0016] of JP-A No. 2000-304932). In addition to the above low-molecular liquid crystalline molecules, high-molecular liquid crystalline molecules can also be used. The high-molecular liquid crystalline molecule is a polymer having a side chain corresponding to the above low-molecular liquid crystalline molecule. Examples of the optical compensation sheet using polymer liquid crystalline molecules include compounds described in JP-A-5-53016.

As the discotic liquid crystalline molecule, various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan, quarterly chemistry review, No. 22). , Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J. Am. Chem. Soc., Vol. 116, page 2655 (1994)). Regarding the polymerization of discotic liquid crystalline molecules, the description of JP-A-8-27284 can be mentioned.
In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] of JP-A No. 2000-155216.
In order to optically compensate a liquid crystal cell in which rod-like liquid crystalline molecules such as STN mode are twisted, it is preferable that the discotic liquid crystalline molecules are also twisted. When an asymmetric carbon atom is introduced into the linking group, the discotic liquid crystal molecules can be twisted and aligned in a spiral shape. Further, even when a compound (chiral agent) having an optical activity containing an asymmetric carbon atom is added to the optically anisotropic layer, the discotic liquid crystalline molecules can be twisted and aligned in a spiral shape.

Two or more kinds of discotic liquid crystal molecules may be used in combination. For example, a polymerizable discotic liquid crystalline molecule and a non-polymerizable discotic liquid crystalline molecule as described above can be used in combination.
The non-polymerizable discotic liquid crystalline molecule is preferably a compound obtained by changing the polymerizable group of the polymerizable discotic liquid crystalline molecule described above to a hydrogen atom or an alkyl group. That is, examples of the non-polymerizable discotic liquid crystalline molecule include compounds described in Japanese Patent No. 2640083.

(Other composition of optically anisotropic layer)
Along with the above liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, a polymer, or the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in JP-A-2002-296423, paragraph numbers [0018] to [0020]. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specifically, for example, compounds described in paragraph numbers [0028] to [0056] of JP-A No. 2001-330725 are exemplified.
The polymer used together with the discotic liquid crystalline molecules is preferably capable of changing the tilt angle of the discotic liquid crystalline molecules.
A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph No. [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to inhibit the alignment of the liquid crystal molecules. It is more preferable.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystal molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

The optically anisotropic layer is a liquid crystalline molecule, or the following polymerizable initiator or any additive (eg, plasticizer, polymerizable monomer, surfactant, cellulose ester, 1,3,5-triazine compound, chiral It is formed by applying a coating solution containing an agent on the alignment film.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide, acetamide, etc.), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, toluene, hexane, Cyclohexane, etc.), alkyl halides (eg, chloroform, dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate, etc.), ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl methone, cyclohexanone, etc.), ethers (eg, tetrahydrofuran) 1,2-dimethoxyethane). Of these, alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.
The coating liquid can be applied by a known method (eg, bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method). A reverse gravure coating method or a die coating method is preferred.

(Fixing the alignment state of liquid crystalline molecules)
The liquid crystalline molecules are preferably substantially uniformly aligned, more preferably fixed in a substantially uniformly aligned state, and the liquid crystalline molecules are fixed by a polymerization reaction. Is most preferred. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.

Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution.

Light irradiation for polymerization of discotic liquid crystalline molecules is preferably performed using ultraviolet rays.
The irradiation energy is preferably 20 mJ / cm ^{2 to} 50 J / cm ² , and more preferably 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 0.7 to 5 μm. However, depending on the mode of the liquid crystal cell, the optically anisotropic layer may be thickened (3 to 10 μm) in order to obtain high optical anisotropy.
As described above, the alignment state of the liquid crystal molecules in the optically anisotropic layer is determined according to the type of display mode of the liquid crystal cell. Specifically, the alignment state of liquid crystal molecules is controlled by the type of liquid crystal molecules, the type of alignment film, and the use of additives (eg, plasticizers, polymers, surfactants) in the optically anisotropic layer. The

Using the polymer film saponified by the alkali saponification method of the polymer film of the present invention, an optical compensation sheet which is one of the preferred embodiments of the optical film of the present invention is produced as described above. As described above, the optical compensation sheet uses a polymer film saponified by the alkali saponification method of the present invention as a transparent support, preferably a layer in which an alignment film and an optically anisotropic layer are laminated in this order. It has a configuration.
The optical compensation sheet exhibits its functions remarkably by being bonded to a polarizing plate or used as a transparent protective film for the polarizing plate (that is, the transparent protective film also serves as a transparent support for the optical compensation sheet).

<Polarizing plate>
The polymer film saponified by the alkali saponification method of the polymer film of the present invention is suitable as an optical film used for a polarizing plate. Specifically, it is preferable to use as a transparent protective film of a polarizing plate having a transparent protective film on both sides of the polarizing film. Moreover, it is particularly preferable to use a surface saponified cellulose acylate film which has been subjected to alkali saponification by the alkali saponification method of the polymer film of the present invention as an optical film. When the polarizing plate is provided with an optical compensation function, specifically, when an optically anisotropic layer is laminated, it is preferable to provide the alkali saponified polymer film on the optically anisotropic layer side. Further, as described above, it is also a preferable aspect to use an optical compensation sheet as at least one of the transparent protective films of the polarizing plate. That is, the polarizing plate of the present invention may be a polarizing plate in which a transparent protective film, a polarizing film, and an optical compensation sheet are laminated in this order, and the optical compensation sheet may be the optical compensation sheet described above.
[Transparent protective film of polarizing plate]
The polarizing plate of the present invention contains a transparent protective film and a polarizing film. That the protective film is transparent means that the light transmittance is 80% or more. As the transparent protective film, generally a cellulose ester film, preferably an acetyl cellulose film is used. The cellulose ester film is preferably formed by the solvent cast method described in the transparent support. The thickness of the transparent protective film is preferably 20 to 200 μm, and more preferably 30 to 100 μm. Especially preferably, it is 30-80 micrometers.

[Surface treatment of optical compensation sheet]
In the present invention, in order to improve the adhesion between the optical compensation sheet and the polarizing film, the surface of the optical compensation sheet on the polarizing film side is preferably surface-treated. As the surface treatment, corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, ozone treatment, acid treatment or alkali treatment is performed.
Examples of treatment methods such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, ozone treatment, acid treatment, and alkali treatment include the contents described in the aforementioned public technical numbers No. 2001-1745 p30-31. . In the present invention, it is preferable to carry out an alkali treatment, and examples of the alkali saponification method of the present invention include the same coating methods as described above in [Coating method in the step of applying an alkaline solution to a polymer film].

[Polarizing film]
The polarizing film used in the present invention is usually preferably a coating type polarizing film represented by Optiva Inc., or a polarizing film comprising a binder and iodine or a dichroic dye.
Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. It is preferable that the iodine and the dichroic dye are aligned along the binder molecule, or the dichroic dye is aligned in one direction by self-assembly such as liquid crystal.
At present, commercially available polarizers (polarizing films) are obtained by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing iodine or dichroic dye to penetrate into the binder. It is common to make it.
Commercially available polarizers have iodine or dichroic dye distributed about 4 μm (about 8 μm on both sides) from the polymer surface, and a thickness of at least 10 μm is necessary to obtain sufficient polarization performance. The penetrability can be controlled by the solution concentration of iodine or dichroic dye, the temperature of the bath, and the immersion time.
As described above, the lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less. When the thickness is 20 μm or less, the light leakage phenomenon is not observed with a 17-inch liquid crystal display device.

As the binder of the polarizing film, either a polymer that can be crosslinked per se or a polymer that is crosslinked by a crosslinking agent can be used. Examples of the polymer include the same polymers as those described for the alignment film.
Most preferred are polyvinyl alcohol and modified polyvinyl alcohol.
The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127.
Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

The binder of the polarizing film may be cross-linked.
As the crosslinked binder, a polymer that can be crosslinked per se can be used. A polarizing film can be formed by reacting a polymer having a functional group or a binder obtained by introducing a functional group into a polymer between the binders by light, heat, or pH change.
Moreover, you may introduce | transduce a crosslinked structure into a polymer with a crosslinking agent.
Crosslinking is generally carried out by applying a coating solution containing a polymer or a mixture of a polymer and a crosslinking agent on a transparent support and then heating. Since it is only necessary to ensure durability at the stage of the final product, the crosslinking treatment may be performed at any stage until the final polarizing plate is obtained.

The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the moisture and heat resistance of the polarizing film are improved.
The polarizing film contains a certain amount of a crosslinking agent that has not reacted even after the crosslinking reaction is completed. However, the amount of the remaining crosslinking agent is preferably 1.0% by mass or less, more preferably 0.5% by mass or less in the polarizing film. In this way, even if the polarizing film is incorporated into a liquid crystal display device and used for a long time or left in a high temperature and high humidity atmosphere for a long time, the degree of polarization does not decrease.
About a crosslinking agent, the description of the US reissue patent 23297 is mentioned. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent.

As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl).
As an example of a dichroic dye, the compound as described in an invention association open technique, a public technical number 2001-1745, page 58 (issue date March 15, 2001) is mentioned, for example.

  In order to increase the contrast ratio of the liquid crystal display device, the transmittance of the polarizing plate is preferably higher and the degree of polarization is preferably higher. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% with respect to light having a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

  It is also possible to dispose the polarizing film and the optically anisotropic layer, or the polarizing film and the transparent support through an adhesive. As the adhesive, a polyvinyl alcohol resin (including a modified polyvinyl alcohol with an acetoacetyl group, a sulfonic acid group, a carboxyl group, or an oxyalkylene group) or an aqueous boron compound solution can be used. A polyvinyl alcohol resin is preferred. The thickness of the adhesive layer is preferably in the range of 0.01 to 10 μm after drying, and particularly preferably in the range of 0.05 to 5 μm.

[Production of polarizing plate]
From the viewpoint of yield, the polarizing film is stretched by tilting the binder at an angle of 10 to 80 ° with respect to the longitudinal direction (MD direction) of the polarizing film (stretching method), or rubbed (rubbing method). It is preferable to dye with a dichroic dye.

  In the case of the stretching method, the tilt angle is preferably stretched so as to match the angle formed between the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. Depending on the bonding angle of the polarizing plate to the liquid crystal cell, the normal tilt angle is 45 ° during stretching. Recently, however, devices that are not necessarily 45 ° have been developed for transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

The draw ratio is preferably 1.1 to 30.0 times, and more preferably 1.5 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 1.2 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. The stretching step may be performed in several steps including oblique stretching. By dividing into several times, it can be stretched more uniformly even at high magnification. Before the oblique stretching, a slight stretching (a degree to prevent shrinkage in the width direction) may be performed horizontally or vertically.
Stretching can be performed by performing tenter stretching in biaxial stretching in different steps. The biaxial stretching is the same as the stretching method performed in normal film formation. In biaxial stretching, stretching is performed at different speeds on the left and right, so that the thickness of the binder film before stretching needs to be different on the left and right. In casting film formation, the flow rate of the binder solution can be differentiated between the left and right sides by tapering the die.
As described above, a binder film that is obliquely stretched by 10 to 80 ° with respect to the MD direction of the polarizing film is manufactured.

In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, orientation is obtained by rubbing the surface of the film in a certain direction using paper, gauze, felt, rubber, nylon, or polyester fiber. Generally, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are planted on average.
It is preferable to carry out using a rubbing roll in which the roundness, cylindricity, and deflection (eccentricity) of the roll itself are all 30 μm or less. The wrap angle of the film on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more.
When rubbing a long film, the film is preferably transported at a speed of 1 to 100 m / min in a constant tension state by a transport device. The rubbing roll is preferably rotatable in the horizontal direction with respect to the film traveling direction for setting an arbitrary rubbing angle. When used in a liquid crystal display device, it is preferable to select an appropriate rubbing angle in the range of 0 to 60 ° in accordance with a liquid crystal device mode described later. More preferably, it is 40 to 50 °, and 45 ° is particularly preferable.

The transparent protective film is preferably disposed on the surface of the polarizing film opposite to the optically anisotropic layer (arrangement of optically anisotropic layer / polarizing film / transparent protective film).
It is also preferred that the transparent protective film is provided with an antireflection film having an outermost surface having antifouling properties and scratch resistance. Any conventionally known antireflection film can be used (described later).

As described above, the polarizing plate of the present invention is produced.
The polarizing plate using the optical film of the present invention or an optical compensation sheet which is one of the preferred embodiments of the optical film is advantageously used for liquid crystal display devices, particularly transmissive liquid crystal display devices.
Hereinafter, a liquid crystal display device, particularly a transmissive liquid crystal display device and its manufacture will be described in detail.

<Liquid crystal display device>
The liquid crystal display device and the transmissive liquid crystal display device of the present invention are formed by using the polarizing plate of the present invention described above, and specifically include a liquid crystal cell and two polarizing plates disposed on both sides thereof. The polarizing plate is a liquid crystal display device comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein at least one of the two transparent protective films disposed between the liquid crystal cell and the polarizing plate is It is an optical film of the present invention, and preferably, the optical film is a polymer film alkali saponified by the alkali saponification method of the polymer film of the present invention as a transparent support, and an alignment film and An optical compensation sheet provided with an optically anisotropic layer.
The liquid crystal cell carries a liquid crystal between two electrode substrates.
One optical compensation sheet is disposed between the liquid crystal cell and one polarizing plate, or two optical compensation sheets are disposed between the liquid crystal cell and both polarizing plates.
A preferred form of the optically anisotropic layer in each liquid crystal mode will be described below.
In the preferred form of the optically anisotropic layer in each liquid crystal mode, the polarizing plate using the optical film of the present invention or the optical compensation sheet which is one of the preferred embodiments of the optical film can be optically compensated advantageously. it can.

(TN mode liquid crystal display device)
The TN mode liquid crystal cell is most frequently used in a color TFT liquid crystal display device, and many literatures are cited. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

(OCB mode liquid crystal display device)
The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. Examples of the liquid crystal display device using the bend alignment mode liquid crystal cell include apparatuses disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.
Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystal molecules rise in the center of the cell and the rod-like liquid crystal molecules lie in the vicinity of the cell substrate. .

(VA mode liquid crystal display device)
In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle ), (3) Liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

(Other liquid crystal display devices)
The ECB mode and STN mode liquid crystal display devices can be optically compensated in the same way as described above.

<Polarizing plate with antireflection function>
In the polarizing plate of the present invention, an antireflection layer having an antireflection function can be further provided on the surface of the protective film of the air side polarizing film. Thereby, reflection of external light is remarkably reduced or eliminated, and a clear image display is possible, which is preferable. The antireflection layer may be provided directly on the transparent protective film of the polarizing film, or an antireflection film having an antireflective layer provided on the transparent support may be bonded to the transparent protective film of the polarizing film. The former embodiment is preferred from the viewpoint of thinning the polarizing plate. Hereinafter, in order to facilitate the description, the latter embodiment will be described.

[Antireflection film]
The antireflection film generally has a low refractive index layer that may have antifouling properties, and at least one layer having a higher refractive index than the low refractive index layer (that is, a high refractive index layer, a medium refractive index layer). Are provided on a transparent support.

  The antireflection film can be formed by laminating transparent thin layers of inorganic compounds (metal oxide, etc.) having different refractive indexes to form a multilayer film; thin by chemical vapor deposition (CVD) or physical vapor deposition (PVD). A method of forming a layer; a post-treatment after forming a colloidal metal oxide particle film by a sol / gel method of a metal compound such as a metal alkoxide (ultraviolet irradiation: JP-A-9-157855, plasma treatment: JP-A-2002-327310) And a method of forming a thin layer. Further, as a method for forming an antireflection film having high productivity, various proposals have been made, such as a method for forming an antireflection film by laminating and applying a thin layer composition in which inorganic particles are dispersed in a matrix. Moreover, the antireflection film formed by this application | coating WHEREIN: The antireflection film which the uppermost layer surface has the shape of a fine unevenness and provided anti-glare property is also mentioned.

(Configuration of coating type antireflection film)
For example, an antireflection film consisting of a layer structure of a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on a transparent support is designed to have a refractive index that satisfies the following relationship: Is done.
The refractive index of the high refractive index layer> the refractive index of the medium refractive index layer> the refractive index of the transparent support> the refractive index of the low refractive index layer.

  Further, the antireflection film may be provided with a hard coat layer between the transparent support and the medium refractive index layer. Further, the antireflection layer may be composed of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer. For example, configurations described in JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706 and the like can be mentioned. Further, other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (for example, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. The hardness of the surface of the antireflection film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K-5400.

(High refractive index layer and medium refractive index layer)
In the present invention, the antireflective film having a high refractive index layer (high refractive index layer and medium refractive index layer) is a curable film containing at least inorganic fine particles having a high refractive index having an average particle size of 100 nm or less and a matrix binder. It is preferable to become.

(Inorganic compound fine particles)
The inorganic compound fine particles used for the high refractive index include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more.

  Examples of these inorganic compounds include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms. , Zr, AL (preferably Co), an inorganic fine particle (hereinafter referred to as “specific oxide”) containing at least one element selected from titanium (preferably Co) (hereinafter sometimes referred to as an element containing such an element). May be referred to as “)”. The total content of contained elements is preferably 0.05 to 30% by mass with respect to Ti, more preferably 0.1 to 10% by mass, still more preferably 0.2 to 7% by mass, particularly preferably. It is 0.3-5 mass%, Most preferably, it is 0.5-3 mass%.

  Said contained element exists in the inside or surface of the inorganic fine particle which has titanium dioxide as a main component. It is more preferable that it exists inside the inorganic fine particles mainly composed of titanium dioxide, and most preferable that it exists both inside and on the surface. These specific metal elements may exist as oxides.

  As another preferable inorganic particle, a composite oxide of at least one metal element (hereinafter also abbreviated as “Met”) selected from metal elements whose oxide has a refractive index of 1.95 or more and a titanium element is used. And the composite oxide is an inorganic fine particle doped with at least one metal ion selected from Co ions, Zr ions, and Al ions (sometimes referred to as “specific composite oxide”). Is mentioned. Here, Ta, Zr, In, Nd, Sb, Sn, and Bi are preferable as the metal element whose refractive index of the oxide is 1.95 or more. In particular, Ta, Zr, Sn, and Bi are preferable. The content of the metal ions doped in the composite oxide is preferably within a range not exceeding 25 mass% with respect to the total amount of metal [Ti + Met] constituting the composite oxide from the viewpoint of maintaining the refractive index. More preferably, it is 0.05-10 mass%, More preferably, it is 0.1-5 mass%, Most preferably, it is 0.3-3 mass%.

  The doped metal ion may exist in any form of metal ion or metal atom, and is appropriately present from the surface to the inside of the complex oxide. It is preferably present both on the surface and inside.

  In order to obtain such ultrafine particles of an inorganic compound, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agent, etc .: JP-A Nos. 1-295503, 11-153703, JP-A 2000-9908, anionic compound or organometallic coupling agent: Japanese Patent Application Laid-Open No. 2001-310432, etc., core / shell structure with high refractive index particles as a core (Japanese Patent Application Laid-Open No. 2001-166104, US Patent) 2003 / 0202137A1) and a combination of specific dispersants (for example, JP-A-11-153703, US Pat. No. 6,210,858B1, JP-A-2002-27776069, etc.).

(Matrix binder)
Examples of the material for forming the matrix of the high refractive index layer include conventionally known thermoplastic resins and curable resin films. Also, at least one selected from a polyvinyl compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. The composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401. Furthermore, colloidal metal oxides obtained from hydrolyzed condensates of metal alkoxides and curable films obtained from metal alkoxide compositions are also preferred. These are described in, for example, JP-A-2001-293818.

  The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm. Further, the refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(Low refractive index layer)
The low refractive index layer is sequentially laminated on the high refractive index layer. The refractive index of the low refractive index layer is preferably in the range of 1.20 to 1.55, and more preferably in the range of 1.30 to 1.50. The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known means for thin film layers including introduction of silicone, introduction of fluorine, and the like can be applied.

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing a fluorine atom in a range of 35 to 80% by mass. Examples of such compounds include paragraph numbers [0018] to [0026] of JP-A-9-222503, paragraph numbers [0019] to [0030] of JP-A-11-38202, and JP-A 2001-40284. Examples thereof include compounds described in paragraph numbers [0027] to [0028], JP 2000-284102 A, JP 2004-45462 A, and the like.

  The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone {for example, “Silane Plain” manufactured by Chisso Co., Ltd.}, silanol group-containing polysiloxane at both ends (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.

  The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is performed simultaneously with or after the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer and the like. It is preferable to carry out by light irradiation or heating.

  A sol / gel cured film in which an organometallic compound such as a silane coupling agent and a silane coupling agent having a specific fluorine-containing hydrocarbon group are cured by a condensation reaction in the presence of a catalyst is also preferable. For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

  The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. It is preferable to contain a low refractive index inorganic compound.

In particular, it is preferable to use hollow inorganic fine particles in order to further reduce the increase in the refractive index of the low refractive index layer. The hollow inorganic fine particles have a refractive index of usually 1.17 to 1.40, preferably 1.17 to 1.37, and more preferably 1.17 to 1.35. The refractive index here represents the refractive index of the entire particle, and does not represent the refractive index of only the outer shell forming the hollow inorganic fine particles. The refractive index of the hollow inorganic fine particles is preferably 1.17 or more from the viewpoint of the strength of the particles and the scratch resistance of the low refractive index layer containing the hollow particles.
The refractive index of these hollow inorganic fine particles can be measured with an Abbe refractometer [manufactured by Atago Co., Ltd.].

  The shape of the inorganic fine particles is preferably a rice grain shape, a spherical shape, a cubic shape, a spindle shape, a short fiber shape, a ring shape, or an indefinite shape.

The porosity of the hollow inorganic fine particles is calculated according to the following equation (5), where r _{i is} the radius of the cavity in the particle and r _o is the radius of the particle outer shell.
Formula (5): w = (r _i / r _o ) ³ × 100

  The porosity of the hollow inorganic fine particles is preferably 10 to 60%, more preferably 20 to 60%, and most preferably 30 to 60% from the viewpoint of the strength of the particles and the scratch resistance of the antireflection film surface. .

  The average particle diameter of the hollow inorganic fine particles in the low refractive index layer is preferably 30 to 100%, more preferably 35 to 80%, and particularly preferably 40 to 60% of the thickness of the low refractive index layer. That is, if the thickness of the low refractive index layer is 100 nm, the particle size of the inorganic fine particles is preferably 30 to 100 nm, more preferably 35 to 80 nm, and particularly preferably 40 to 60 nm. When the average particle size is in the above range, the strength of the antireflection film is sufficiently expressed.

  Other additives contained in the low refractive index layer include organic fine particles described in paragraphs [0020] to [0038] of JP-A No. 11-3820), silane coupling agents, slip agents, surfactants, and the like. Can be contained.

  When the outermost layer is further formed on the low refractive index layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). Although it is good, it is preferably formed by a coating method because it can be manufactured at a low cost. The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

{Other layers of antireflection film}
The antireflection film may further be provided with a hard coat layer, a forward scattering layer, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like.

(Hard coat layer)
The hard coat layer is provided on the surface of the transparent support (or transparent protective film; the same applies hereinafter) in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.

  The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound. Specific examples of these compounds are the same as those exemplified for the high refractive index layer. Specific examples of the composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.

  The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer. The hard coat layer can also serve as an antiglare layer that contains particles having an average particle size of 0.2 to 10 μm and has an antiglare function (antiglare function: described later).

  The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.

  The hardness of the hard coat layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K-5400. Further, the scratch resistance of the hard coat layer is preferably as the wear amount of the test piece coated with the hard coat layer before and after the test is smaller in the Taber test according to JIS K-5400.

(Forward scattering layer)
The front scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is tilted in the vertical and horizontal directions when a polarizing plate with an antireflection function is applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function. As for the forward scattering layer, for example, Japanese Patent Application Laid-Open No. 11-38208 with a specific forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 with a relative refractive index of a transparent resin and fine particles in a specific range, and a haze value of 40% or more. JP-A-2002-107512 and the like which are defined as follows.

  Each layer constituting the antireflection layer is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US Pat. No. 2,681,294). Thus, it can be formed by coating.

(Anti-glare function)
The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 50%, more preferably 5 to 30%, and most preferably 5 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a relatively large particle (particle size 0.05 to 2 μm) is added to a hard coat layer in a small amount (0.1 to 50% by mass) to form a surface uneven film, and these shapes are maintained on it. A method of providing a low refractive index layer (for example, JP-A-2000-281410, 2000-95893, 2001-100004, 2001-281407, etc.), uppermost layer (antifouling layer) A method of physically transferring an uneven shape onto the surface after coating (for example, as an embossing method, described in JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401, etc.) And the like.

  The present invention will be illustrated below by examples and comparative examples, but the present invention is not limited to these examples.

[Example 1]
<Production of polymer film>

(Preparation of cellulose acylate film (CAF-1))
The following composition was put into a mixing tank and stirred while heating at 30 ° C. to dissolve each component to prepare a cellulose acylate solution (SA-1) (inner layer dope and outer layer dope).
Regarding the silica fine particles of the cellulose acylate solution for the outer layer, 20 parts by mass of the following silica fine particles and 80 parts by mass of methanol were thoroughly stirred for 30 minutes to obtain a mixed silica molecular dispersion.

(Cellulose acylate (SA-1) solution composition)
Cellulose acylate solution composition (parts by mass) For inner layer For outer layer Cellulose acetate with an acyl substitution degree of 2.87 100 100
Triphenyl phosphate (plasticizer) 7.8 7.8
Biphenyl diphenyl phosphate (plasticizer) 3.9 3.9
Methylene chloride (first solvent) 293 314
Methanol (second solvent) 71 76
1-butanol (third solvent) 1.5 1.6
Silica fine particles (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
0 0.8
Retardation adjuster A 1.50

Retardation adjuster A

  When the particle size distribution of the silica fine particle dispersion was measured for the obtained outer layer dope, the particle size of 500 nm or more was 0%. Here, the volume average particle diameter was measured with a “particle size distribution measuring apparatus LA920 (manufactured by Horiba Seisakusho)”.

(Preparation of cellulose acylate film)
The obtained inner layer dope and outer layer dope were cast on a drum cooled to −5 ° C. using a three-layer co-casting die.
The drum had an arithmetic average roughness (Ra) of 0.006 μm, a maximum height (Ry) of 0.06 μm, and a ten-point average roughness (Rz) of 0.009 μm. The arithmetic average roughness (Ra), maximum height (Ry), ten-point average roughness (Rz), and average interval of surface irregularities (Sm) were measured according to JIS B 0601-1994.
The film having a residual solvent amount of 70% by mass is peeled off from the drum, and dried at 80 ° C. while being transported with a draw ratio in the conveyance direction of 110% while holding both ends with a pin tenter, and the residual solvent amount becomes 10% by mass. It was dried at 110 ° C. Thereafter, it was dried at a temperature of 140 ° C. for 30 minutes to prepare a cellulose acylate film (CAF-1, outer layer: 3 μm, inner layer: 74 μm, outer layer: 3 μm) having a residual solvent of 0.3% by mass. The obtained CAF-1 had a width of 1340 mm and a thickness of 80 μm.
The obtained film CAF-1 had an in-plane slow axis in the longitudinal direction, Re (630) was 8 nm, and | Rth (630) | was 80 nm. In addition, | Re (400) −Re (700) | was 8 nm, and | Rth (400) −Rth (700) |

(Uneven shape on the film surface)
The surface shape of the band side surface of the obtained cellulose acylate film CAF-1 was measured. The results are shown in Table 1. Table 1 also shows the results of evaluating the following optical characteristics and mechanical characteristics.

{Evaluation method of optical properties}
(Retardation value)
Re retardation value Re (λ) and Rth retardation value Rth (λ) at wavelength λnm were measured with KOBRA21ADH (manufactured by Oji Scientific Instruments). In this example, values measured at a wavelength of 590 nm are shown unless otherwise specified.
(Slow axis deviation)
The off-axis angle was measured with an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments). Each measurement was performed at 10 points in the width direction, and an average value was obtained.
(Haze)
Haze was measured using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.). Five points were measured per film sample, and the average value was adopted.

{Measuring method of mechanical properties}
(curl)
The curl value was measured according to a measurement method (ANSI / ASCPH1.29-1985, Method-A) defined by the American National Standards Institute. The polymer film is cut to a size of 35 mm in the width direction and 2 mm in the longitudinal direction, and then placed on the curl plate. The curl value is read after conditioning for 1 hour in an environment of temperature 25 ° C. and relative humidity 65%. Similarly, the polymer film is cut to a size of 2 mm in the width direction and 35 mm in the longitudinal direction, and then placed on the curl plate. The curl value is read after conditioning for 1 hour in an environment of temperature 25 ° C. and relative humidity 65%. Measurement was made in two directions, the width direction and the longitudinal direction, and the larger value of both values was taken as the curl value. The curl value is represented by the reciprocal of the radius of curvature (m).
(Tear strength)
A film is cut into 65 mm × length 50 mm to prepare a sample. This sample was conditioned for 2 hours or more in a room at a temperature of 30 ° C. and a relative humidity of 85%, and in accordance with the ISO 6383 / 2-1983 standard, a load (g )

  As shown in Table 1 above, the cellulose acylate film (CAF-1) had a good surface shape, and the surface shape was uniform with the values shown in Table 1. In addition, the optical properties of retardation value, slow axis angle deviation and haze value and the mechanical properties of curl and tear strength were also good.

<Alkali saponification treatment>
The following alkali saponification treatment was performed on one surface of the film CAF-1.
That is, after passing the film (CAF-1) on a dielectric heating roll having a temperature of 60 ° C. and raising the film surface temperature to 40 ° C., an alkali solution (S-1) having the composition shown below was placed on a rod coater. The coating was applied at a coating amount of 17 mL / m ² and was allowed to stay for 10 seconds under a steam far infrared heater manufactured by Noritake Co., Ltd., heated to 110 ° C. Subsequently, using the same rod coater, primary cleaning is performed with the alkaline diluent shown in Table 2 (in the table, the residual amount of the primary cleaning liquid is the liquid of the alkali mixed solution re-coated on the polymer film on the secondary side of the coater. Subsequently, cleaning was performed with the cleaning water shown in Table 2 (in the table, the remaining amount of the cleaning liquid indicates the amount of liquid on the secondary side of the coater). At this time, the temperature of the alkali diluted solution and the washing water were both 35 ° C. Next, surface saponified film samples (CFS-01 to 10 and CFS-51 to 53) were prepared by allowing them to stay in a drying zone at 70 ° C. for 5 seconds and drying.

(Alkaline solution (S-1) composition)
Potassium hydroxide 8.6 parts by weight Water 24.1 parts by weight Isopropanol 56.3 parts by weight Surfactant (K-1: C ₁₆ H ₃₃ O (CH ₂ CH ₂ O) ₁₀ H) 1.0 part by weight Propylene glycol 10.0 parts by mass

(Alkaline solution (S-1) physical properties)
Surface tension (35 ° C) 20mN / m
(The surface tension was measured using an automatic surface tension meter CBVP-Z type (manufactured by Kyowa Interface Science Co., Ltd.) while keeping the temperature of the sample at 35 ° C.)
Viscosity (35 ° C) 5.2 mPa · s
(Viscosity was measured using a vibrating viscometer CVJ5000 (manufactured by A & D Co., Ltd.) while maintaining the temperature of the sample at 35 ° C.)

{Characteristics of film after alkali saponification treatment (after hydrophilization surface treatment)}
About each produced film, the following tests were done and the effect of the alkali saponification process was confirmed. The results are shown in Table 2.

(Surface shape: foreign matter, turbidity)
The saponified film was cut out to a length of 1 m in the longitudinal direction in the full width, and the sample was observed visually and with a loupe for light and foreign matter and turbidity while allowing light to pass through the shaucus ten, and evaluated using the following criteria.
◯: No foreign matter or turbidity is observed at all (evaluated by 10 people, a level that no one can recognize)
○ ': The occurrence of foreign matter and turbidity is recognized very weakly (level that can be evaluated by 10 people and recognized by one person)
Δ: Foreign matter and turbidity are weakly generated (level evaluated by 10 people and recognized by 2 to 5 people)
X: Foreign matter and turbidity are strongly generated (level evaluated by 10 people and recognized by 6 or more people)

(Change amount of phosphorus element in width direction: P change amount in width direction)
Nine-point sampling was performed in the width direction with respect to the saponification direction of the polymer film, and the amount of carbon atoms and phosphorus atoms on the surface of the saponified film was measured by using a photoelectron spectrometer {manufactured by Shimadzu Corporation, "ESCA750" type} It was measured as a peak value with respect to the reference line of P2p, and the area ratio was calculated as a P amount (P / C). The difference between the maximum value and the minimum value is shown in Table 2 as the amount of change in the phosphorus element amount in the width direction.

  As shown in Table 2, in the films of Examples 1 to 10 (CFS-01 to 10), the amount of P change in the width direction was 0.004 at the maximum within a plane of 1 square meter. Generation of foreign matter and turbidity was not observed on the entire surface of the film.

On the other hand, in Comparative Examples 1 and 2 (CFS-51, 52) in which the washing process was performed by “Fountain Coater / Air Knife” instead of the rod coater, the surface condition after treatment was slightly deteriorated, but Comparative Example 3 (CFS- 53), the surface condition clearly deteriorated. In the comparative example, the amount of change in the width direction of P was also large. Further, in Comparative Example 2 in which the “Fountain Coater / Air Knife” was washed less, the surface condition was worse than that in Comparative Example 1. On the other hand, it can be seen that Example 3 in which the number of cleaning times of the rod coater is small does not change in surface shape even when compared with Example 1. Therefore, it can be seen that cleaning with a rod coater is superior to cleaning with a “fountain coater / air knife”.
As described above, it has been clarified that the surface saponified cellulose acylate films of the present invention of Examples 1 to 10 are uniformly hydrophilized in the plane.

<Preparation of optical compensation sheet>
Each saponification film (CFS-01-10, 51-53) was used as a transparent support to produce an optical compensation sheet.

(Formation of alignment film)
On the saponified surface of each transparent support (CFS-01~10,51~53), was applied at a coverage of 24 mL / m ² alignment layer coating solution (O-1) by a rod coater having the following composition. Drying was performed with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds.

(Alignment film coating solution (O-1) composition)
Modified polyvinyl alcohol (PVA) 4 parts by mass Citric acid and 1,2,3 ethyl ester mixture 0.06 parts by weight Glutaraldehyde 0.5 parts by weight Water 700 parts by weight Methanol 300 parts by weight

Modified PVA

(Formation of optically anisotropic layer)
Next, for the transparent support on which the alignment film was formed, an optically anisotropic layer was formed as follows to obtain optical compensation sheets.
That is, after rubbing the alignment film in the longitudinal direction of the transparent support on which the alignment film is formed, the following discotic liquid crystal coating solution (DA-1) is applied onto the alignment film with a # 4 wire bar coater. Then, after heating for 3 minutes in a high-temperature bath at 125 ° C. to align the discotic liquid crystal, UV irradiation was performed at 500 mJ / cm ² using a high-pressure mercury lamp, and the mixture was allowed to cool to room temperature. An optical compensation sheet was produced.

(Discotic liquid crystal coating liquid (DA-1) composition)
The following discotic liquid crystal DLC-A 9.1 parts by mass Ethylene oxide-modified trimethylolpropane acrylate (V # 360, trade name, Osaka Organic Chemical Co., Ltd.) 0.9 parts by mass Cellulose acetate butyrate (CAB551-0.2, Product name, manufactured by Eastman Chemical Co., Ltd.) 0.2 parts by mass Cellulose acetate butyrate (CAB531-1, product name, manufactured by Eastman Chemical Co., Ltd.) 0.05 parts by mass The following fluorine compound (F-1) 1.3 parts by mass Cure 907 (trade name, manufactured by Ciba Geigy) 3.0 parts by weight Kaya Cure DETX (trade name, manufactured by Nippon Kayaku Co., Ltd.) 0.1 parts by weight Methyl ethyl ketone 29.6 parts by weight

Discotic liquid crystal DLC-A

Fluorine compound (F-1)

The thickness of the optically anisotropic layer of each sheet was 1.6 μm.
Moreover, the following performance evaluation tests were done about each obtained optical compensation sheet. The results are shown in Table 3.

{Performance evaluation test of optical compensation sheet}
(Adhesion)
Optical compensation sheets CFO-01 to 10 and 51 to 53 shown in Table 3 were attached to a glass plate using an acrylic adhesive and stored at 90 ° C. for 20 hours. The acrylic adhesive is the same as that used for assembling the liquid crystal display device, and the glass plate is the same as that used for the liquid crystal cell. The optical compensation sheet was peeled off from the glass plate in the vertical direction, and the adhesion was evaluated by examining the portion where the peeling residue occurred.
◎: Not generated at all (level that 10 people can evaluate and no one can recognize)
○: Slightly generated (level evaluated by 10 people and recognized by 1 to 3 people)
Δ: Weak occurrence (level evaluated by 10 people and recognized by 3-5 people)
X: Strongly generated (level evaluated by 10 people and recognized by 6 or more people)

(Uneven transmission light)
Each optical compensation sheet was sandwiched between two polarizing plates arranged in crossed Nichols, and the unevenness of transmitted light was visually observed for sensory evaluation.
○: Not generated at all (a level at which 10 people evaluate and one cannot recognize)
○ ′: Very weakly generated (level evaluated by 10 people and recognized by 1 person)
Δ: Weak occurrence (level evaluated by 10 people and recognized by 2 to 5 people)
X: Strongly generated (level evaluated by 10 people and recognized by 6 or more people)

<Preparation of polarizing plate>
(Preparation of polarizing film (HF-01))
PVA having an average polymerization degree of 4000 and a saponification degree of 99.8 mol% was dissolved in water to obtain a 4.0% aqueous solution.
This solution was band-cast using a die having a taper and dried, and formed into a film so that the width before stretching was 110 mm, the thickness was 120 μm at the left end, and 135 μm at the right end.
The film was peeled off from the band, obliquely stretched in the 45 ° direction in a dry state, and immersed in an aqueous solution of iodine 0.5 g / L and potassium iodide 50 g / L for 1 minute at 30 ° C., and then boric acid 100 g / L. L, immersed in an aqueous solution of 60 g / L of potassium iodide at 70 ° C. for 5 minutes, further washed with water at 20 ° C. for 10 seconds and then dried at 80 ° C. for 5 minutes to form an iodine-based polarizing film (HF-01) Obtained. The polarizing film had a width of 660 mm and a thickness of 20 μm on both sides.

(Preparation of polarizing plate)
In the surface saponified film sample (CFS-01) on the transparent support side film surface (surface opposite to the orientation film on the transparent support) of each optical compensation sheet (CFO-01 to 10, 51 to 53) One-side saponification treatment was performed in the same manner as the alkali saponification treatment on the alignment film side. Using a polyvinyl alcohol-based adhesive, the one-side saponified side was attached to one side of the polarizing film (HF-01).
Further, a cellulose triacetate film (TD-80UF: manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm was subjected to saponification treatment on one side in the same manner as the alkali saponification treatment on the alignment film side in the surface saponification film sample (CFS-01). The saponified surface was attached to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive.
The transmission axis of the polarizing film and the slow axis of the cellulose acylate film (CAF-01) were arranged in parallel. The transmission axis of the polarizing film and the slow axis of the cellulose triacetate film were arranged so as to be orthogonal. In this way, polarizing plates (HB-01 to 10, 51 to 53) were produced.

<Production of liquid crystal display device>
A pair of polarizing plates provided in a liquid crystal display device using a TN type liquid crystal cell (RDT195S, manufactured by Mitsubishi Electric Corporation) is peeled off, and instead of each of the polarizing plates prepared above, the optical compensation sheet is on the liquid crystal cell side. Each sheet was attached to the observer side and the backlight side through an adhesive so that The transmission axis of the polarizing plate on the viewer side and the transmission axis of the polarizing plate on the backlight side were arranged to be in the O mode.
The following evaluation tests were performed on the obtained liquid crystal display device. The results are shown in Table 3.

(Evaluation of unevenness in drawn images)
About the liquid crystal display device produced in this way, the drawing unevenness at the time of black display (L1) was visually observed using a measuring machine (EZ-Contrast 160D, manufactured by ELDIM).
○: Not generated at all (a level at which 10 people evaluate and one cannot recognize)
Δ: Weak occurrence (level evaluated by 10 people and recognized by 1 to 5 people)
X: Strongly generated (level evaluated by 10 people and recognized by 6 or more people)

  As is apparent from the results shown in Table 3, each optical compensation sheet, which is a preferred embodiment of the optical film of the present invention, has good adhesion and is very good with no unevenness in transmitted light.

Further, as is apparent from the results shown in Table 3, optical compensation sheets (CFO-01 to CFO-01 to C) that use a cellulose acylate film (CFS-01 to 10) saponified by the alkali saponification method of the present invention as a transparent support. The liquid crystal display device (CFL-01 to 10) of the present invention using 10) is a clear, high-brightness image with no unevenness of the drawn image, no fogging of the entire screen, and excellent contrast and viewing angle. A drawn image was obtained. That is, the visibility was good. On the other hand, the film using the comparative film (CFO-51 to 53) was uneven over the entire screen and was problematic for practical use.
From the above visual observation results, the polarizing plate using the optical compensation sheet using the polymer film obtained by the alkali saponification method of the present invention as a transparent support has good optical properties and is provided with it. It can be seen that the liquid crystal display device has excellent drawing properties.

Next, an example in which an OCB mode liquid crystal display device is produced will be described.
[Example 11]
<Production of polymer film>
(Preparation of fine particle dispersion (RL-1))
A solution having the following composition was prepared and dispersed with an attritor so as to have a volume average particle diameter of 80 nm to obtain a fine particle dispersion. When the particle size distribution of the obtained fine particle dispersion was measured, the number of particles having a particle size of 500 nm or more was 0%.
Here, the volume average particle diameter was measured with a “particle size distribution measuring apparatus LA920 (manufactured by Horiba Seisakusho)”.

(Fine particle dispersion (RL-1) composition)
Hydrophobic silica (trade name “AEROSIL R812” (modified methyl group,
Primary particle size 7 nm: Nippon Aerosil Co., Ltd.) 2.00 parts by weight Cellulose triacetate having an acetylation degree of 60.7% (6-position substitution degree: 0.90)
2.00 parts by weight Triphenyl phosphate 0.16 parts by weight Biphenyl diphenyl phosphate 0.08 parts by weight Methylene chloride 78.70 parts by weight Methanol 14.20 parts by weight 1-butanol 2.86 parts by weight

(Preparation of cellulose acylate solution (SA-2))
Each component shown in the following cellulose acylate solution (SA-2) composition was put into a mixing tank and heated and stirred to prepare a cellulose acylate solution.

(Cellulose acylate solution (SA-2) composition)
Cellulose triacetate with an acetylation degree of 60.7% (6-position substitution degree: 0.90)
100 parts by mass Triphenyl phosphate 7.8 parts by mass Biphenyl diphenyl phosphate 3.9 parts by mass The fine particle dispersion (RL-1) (as solid content) 0.45 parts by mass Methylene chloride 300 parts by mass Methanol 54 parts by mass 1-butanol 11 parts by mass

  Each component shown in the following retardation adjuster solution (RE-1) composition was put into another mixing tank, and heated and stirred to prepare a retardation adjuster solution.

(Retardation adjuster solution (RE-1) composition)
The following retardation adjuster (446) 16 parts by mass Methylene chloride 82 parts by mass Methanol 15 parts by mass 1-butanol 3 parts by mass

Retardation adjuster (446)

Obtained by adding 22 parts by mass of the retardation adjusting agent solution (RE-1) to 474 parts by mass of the cellulose acylate solution (SA-2) and stirring the mixture for 3 hours at room temperature (25 ° C.). The non-uniform gel solution was cooled at −70 ° C. for 6 hours, and then heated to 50 ° C. and stirred to obtain a completely dissolved dope.
The dope is filtered at 50 ° C. with a filter paper having an absolute filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63), and further filtered with a filter paper having an absolute filtration accuracy of 0.0025 mm (manufactured by Pall, FH025). Filtration and defoaming were performed.
Next, the dope after detachment was cast using a band casting machine. In addition, the arithmetic average roughness (Ra) of the metal support in the band casting machine is 0.006 μm. After the film surface temperature on the band reaches 40 ° C., after drying for 1 minute and peeling off, the drying temperature is 120 ° C. A cellulose acylate film (CAF-101) (thickness: 90 μm) having a residual solvent amount of 0.3 mass% was produced.
When the retardation of the prepared film (CAF-101) was measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the retardation Rth (550) in the thickness direction was The retardation Re (550) in the front direction at 77 nm was 7 nm.

(Uneven shape on the film surface)
Table 4 shows the surface irregularities of the obtained cellulose acylate film (CAF-101).

<Alkali saponification treatment>
The following alkali saponification treatment was performed on one side of the film (CAF-101).
That is, a dielectric heating roll having a temperature of 60 ° C. is passed over the film (CAF-101) and the film surface temperature is raised to 40 ° C., and then the alkaline solution (S-1) of Example 1 is applied to the rod coater. was coated at a coverage of 14 mL / m ² by using, 110 ° C. to heating (saponification temperature) was Corp. 8 seconds (saponification time) under the Noritake made of steam-type far-infrared heater was retained. Subsequently, using a rod coater, an alkaline dilution {pure water / acetone = 90/10 (mass ratio), surface tension at 35 ° C. 47 mN / m} was applied to perform primary cleaning. At this time, the residual amount of the primary cleaning liquid (indicating the liquid volume of the alkali mixed solution recoated on the polymer film on the secondary side of the coater) was 2.8 mL / m ² , and the film temperature was 45 ° C. Next, washing water application / water draining with a rod coater (washing liquid remaining amount 2.8 mL / m ² ) was repeated three times, and then dried by staying in a drying zone at 70 ° C. for 5 seconds to obtain a surface saponified film sample (CFS-101) Was made.
The film (CFS-101) has a contact angle with water of 36 to 38 ° in a plane of 1 square meter, and the P change in the width direction (difference between the maximum value and the minimum value) is 0.002. This was a uniform treatment with no variation. Generation of foreign matter and turbidity was not observed on the entire surface of the film.
As described above, it can be seen that the alkali saponification method of the present invention can be made hydrophilic without deteriorating the surface state.

<Preparation of optical compensation sheet>
An optical compensation sheet was prepared using a saponification film (CFS-101) as a transparent support.
(Formation of alignment film)
On the saponification surface of the transparent support (CFS-101), an alignment film coating solution (O-2) having the following composition was coated with a rod coater at a coating amount of 32 mL / m ² . Drying was performed with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds.

(Alignment film coating solution (O-2) composition)
The following modified polyvinyl alcohol 20 parts by mass The following carboxylic acid compound (A-1) 0.07 parts by mass Glutaraldehyde 0.5 parts by mass Water 360 parts by mass Methanol 120 parts by mass

Modified polyvinyl alcohol (average polymerization degree: 4000)

Carboxylic acid compound (A-1)

(Formation of optically anisotropic layer)
The alignment film formed with the alignment film coating solution (O-2) was rubbed in the direction of 45 ° with the slow axis (measured at a wavelength of 632.8 nm) of the transparent support.
The following discotic liquid crystal coating solution (DA-2, solid content concentration 35.5%; MEK solvent) was applied at 5.2 mL / m ² , followed by heating in a thermostatic bath at 130 ° C. for 2 minutes, The disk-like compound was oriented and polymerized by irradiation with UV at 130 ° C. for 1 minute using a 120 W / cm high-pressure mercury lamp. Then, it stood to cool to room temperature. Thus, an optically anisotropic layer was formed, and an optical compensation sheet (CFO-101) was produced.

(Discotic liquid crystal coating solution (DA-2) composition)
The following discotic liquid crystal DLC-B 9.1 parts by mass Ethylene oxide-modified trimethylolpropane acrylate (V # 360, Osaka Organic Chemical Co., Ltd.) 0.9 parts by mass Cellulose acetate butyrate 0.1 parts by mass (CAB531-1 yeast Man chemical)
Irgacure 907 0.3 parts by mass Kayacure DETX (manufactured by Nippon Kayaku Co., Ltd.) 0.1 parts by mass The fluorine compound (F-1) 0.04 parts by mass

Discotic liquid crystal DLC-B

The Re retardation value of the optically anisotropic layer measured at a wavelength of 632.8 nm was 38 nm. The angle (tilt angle) between the disk surface and the alignment film was 34 ° on average.
Further, the produced optical compensation sheet (CFO-101) had no transmitted light unevenness and good adhesion.

<Production of elliptically polarizing plate>
(Preparation of polarizing film)
PVA having an average polymerization degree of 4000 and a saponification degree of 99.8 mol% was dissolved in water to obtain a 4.0% aqueous solution.
This solution was band-cast using a die having a taper and dried to form a film so that the width before stretching was 110 mm, the thickness was 120 μm at the left end, and 135 μm at the right end.
The film was peeled off from the band, obliquely stretched in the 45 ° direction in a dry state, and immersed in an aqueous solution of iodine 0.5 g / L and potassium iodide 50 g / L for 1 minute at 30 ° C., and then boric acid 100 g / L. L, immersed in an aqueous solution of potassium iodide 60 g / L at 70 ° C. for 5 minutes, further washed with water at 20 ° C. for 10 seconds and then dried at 80 ° C. for 5 minutes to form an iodine-based polarizing film (HF-02) Obtained. The polarizing film had a width of 660 mm and a thickness of 20 μm on both sides.

(Preparation of polarizing plate)
Alkali saponification treatment on the alignment film side in the surface saponified film sample (CFS-101) on the transparent support side film surface of the optical compensation sheet (CFO-101) (surface opposite to the alignment film on the transparent support) The saponification treatment on one side was performed in the same manner as described above. Using a polyvinyl alcohol-based adhesive, the one-side saponified side was attached to one side of the polarizing film. Further, a cellulose triacetate film (TD-80UF: manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm was subjected to saponification treatment on one side in the same manner as the alkali saponification treatment on the alignment film side in the surface saponification film sample (CFS-01). The saponified surface was attached to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive.
The transmission axis of the polarizing film and the slow axis of the cellulose acylate film (CAF-101) were arranged in parallel. The transmission axis of the polarizing film and the slow axis of the cellulose triacetate film were arranged so as to be orthogonal. In this way, a polarizing plate was produced.

<Production of liquid crystal display device>
A pair of polarizing plates provided in a liquid crystal display device using an OCB type liquid crystal cell (VT23XD1, manufactured by Nanao Co., Ltd.) is peeled off, and the polarizing plate prepared above is replaced with an optical compensation sheet (CFO-101). A liquid crystal display device (CFL-101) is arranged such that the rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing the liquid crystal cell are antiparallel through an adhesive so as to be on the liquid crystal cell side. Was made.

{Evaluation of LCD devices}
(Evaluation of unevenness in drawn images)
The liquid crystal display device thus produced was visually observed for drawing unevenness during black display (L1) using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). The liquid crystal display device of the present invention ( CFL-101) exhibited good display performance in which no unevenness could be visually confirmed.

(Drawing image contrast and viewing angle)
Next, a rectangular wave voltage of 55 Hz was applied to the liquid crystal cell of the liquid crystal display device (CFL-101) of the present invention. In the normally white mode, the voltage at which the transmissivity is the lowest for white display 2V and black display was set as the black display voltage in each liquid crystal cell. Using the transmittance ratio (white display / black display) as the contrast ratio, the viewing angle at which a top / bottom / left / right contrast ratio of 10 was obtained was measured. When the driving voltage was 4.1 V, the upper viewing angle was 78 ° and the lower viewing angle was 67. °, right viewing angle 80 °, left viewing angle 80 °.

Next, an example in which an IPS mode liquid crystal display device is produced will be described.
[Example 12]
<Production of polymer film>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acylate solution. The solution was filtered using a filter paper (No. 63, manufactured by Advantech) having a retained particle diameter of 4 μm and a drainage time of 35 seconds at 5 kg / cm ² or less.

(Cellulose acylate solution SA-3 composition)
Cellulose acetate having an acetylation degree of 60.9% (degree of polymerization: 300, Mn / Mw = 1.5) 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 300 parts by mass Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass

  In another mixing tank, 8 parts by mass of the retardation adjusting agent A, 10 parts by mass of the following retardation adjusting agent B, 0.28 parts by mass of silicon dioxide fine particles (average particle size: 0.1 μm), 80 parts by mass of methylene chloride. And 20 parts by mass of methanol were added and stirred while heating to prepare a retardation adjusting agent solution (and a fine particle dispersion) RE-2. 40 parts by mass of the retardation modifier solution (RE-2) was mixed with 474 parts by mass of the cellulose acylate solution (SA-3), and the dope was prepared by sufficiently stirring.

Retardation adjuster B

  The obtained dope was cast using a band casting machine. A film having a residual solvent amount of 15% by mass was stretched transversely at a stretch ratio of 20% using a tenter under the conditions of 130 ° C., held at 50 ° C. for 30 seconds with the stretched width, and then clipped to remove cellulose. An acylate film was produced. The amount of residual solvent at the end of stretching was 5% by mass and further dried to prepare a polymer film (CAF-102) with the residual solvent amount being less than 0.1% by mass.

  The thickness of the polymer film (CAF-102) thus produced was 80 μm. About the produced polymer film (CAF-102), Re is 70 nm by measuring the light incident angle dependence of Re using an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd.). , Rth was 175 nm, and from this, it was found that Nz was 3.0.

<Alkali saponification treatment>
The following alkali saponification treatment was performed on one surface of the produced polymer film (CAF-102).
That is, after passing a dielectric heating roll having a temperature of 60 ° C. over the film and raising the film surface temperature to 40 ° C., the following alkaline solution (S-2) was applied at a coating amount of 14 mL / m using an extrusion coater. ^The coating was carried out at ² and kept for 8 seconds (saponification time) under a steam far-infrared heater manufactured by Noritake Co., Ltd., heated to 110 ° C. (saponification temperature). Subsequently, an alkali dilution solution {pure water / acetone = 90/10 (mass ratio), surface tension at 35 ° C. of 47 mN / m} was applied using a rod coater to perform primary cleaning. At this time, the residual amount of the primary cleaning liquid (indicating the liquid volume of the alkali mixed solution recoated on the polymer film on the secondary side of the coater) was 2.8 mL / m ² , and the film temperature was 45 ° C. Further, an alkali dilution solution (pure water / methanol = 90/10 (mass ratio)) was applied using a rod coater to dilute the alkali solution and perform secondary cleaning. At this time, the remaining amount of the secondary cleaning liquid was 1.4 mL / m ² , and the film temperature was 45 ° C. Next, washing water application (washing water temperature: 45 ° C.) / Draining with a rod coater was repeated twice, and then the saponification-treated transparent support (CFS-102) was produced by staying in a drying zone at 70 ° C. for 5 seconds and drying. .

(Alkaline solution (S-2) composition)
Potassium hydroxide 8 parts by weight Water 24 parts by weight Isopropanol 56 parts by weight Surfactant (K-2: C ₁₀ H ₂₁ O (CH ₂ CH ₂ O) ₂₀ H) 1 part by weight Propylene glycol 10 parts by weight

(Alkaline solution (S-2) properties)
Surface tension (35 ° C) 20mN / m
Viscosity (35 ° C) 5.2 mPa · s

The film (CFS-102) has a contact angle with water of 36 to 38 ° in a plane of 1 square meter, and the P change in the width direction (difference between the maximum value and the minimum value) is 0.002. This was a uniform treatment with no variation. Generation of foreign matter and turbidity was not observed on the entire surface of the film.
As described above, according to this example, it can be seen that a plurality of rod coaters can be used and a plurality of types of diluents can be used to make the surface hydrophilic without deterioration.

<Production of retardation plate>
An optical compensation sheet was prepared using a saponified film (CFS-102) as a transparent support.
(Preparation of vertical alignment film)
A commercially available vertical alignment film (JALS-204R, manufactured by Nippon Synthetic Rubber Co., Ltd.) was diluted 1: 1 with methyl ethyl ketone on the saponified surface of this film (CFS-102), and then 2.4 ml / min with a wire bar coater. m ^{2 was} applied and dried with 120 ° C. hot air for 120 seconds.

(Production of retardation layer)
Next, 3.8 g of the following rod-shaped liquid crystal compound, 0.06 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy), 0.02 g of a sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.), the following air interface A solution was prepared by dissolving 0.002 g of the side vertical alignment agent in 9.2 g of methyl ethyl ketone.
This solution was applied to the alignment film side of the film on which the alignment film was formed with a bar coater at 7.8 mL / m ² and heated in a 100 ° C. constant temperature bath for 2 minutes to align the rod-like liquid crystal compound, and then at 80 ° C. A 120 W / cm high-pressure mercury lamp was irradiated with UV for 20 seconds to crosslink the rod-like liquid crystal compound to produce a retardation layer, and an optical compensation film (CFO-102) was produced.

Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the optical incident angle dependency of Re of the manufactured optical film (CFO-102) was measured, and the pre-measured support was measured. By calculating the optical characteristics of only the second retardation region by subtracting the contribution, the second retardation region has Re of 0 nm and Rth of −225 nm, and the rod-like liquid crystal is aligned substantially vertically. It was confirmed.
Further, the produced optical film (CFO-102) had no transmitted light unevenness and good adhesion.

<Production of Polarizing Plate Transparent Protective Film 1>
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acetate solution A was prepared.

(Cellulose acetate solution A composition)
Cellulose acetate having a substitution degree of 2.86 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 300 parts by weight Methanol (second solvent) ) 54 parts by mass 1-butanol 11 parts by mass

  The following composition was charged into another mixing tank, stirred while heating to dissolve each component, and an additive solution B-1 was prepared.

(Additive solution B-1 composition)
Methylene chloride 80 parts by mass Methanol 20 parts by mass The following optical anisotropy reducing agent 40 parts by mass

Optical anisotropy reducing agent

40 parts by mass of the additive solution B-1 was added to 477 parts by mass of the cellulose acetate solution A, and the dope was prepared by sufficiently stirring. The dope was cast from a casting port onto a drum cooled to 0 ° C. The film is peeled off at a solvent content of 70% by mass, and both ends in the width direction of the film are fixed with a pin tenter (the pin tenter described in FIG. 3 of JP-A-4-1009), and the solvent content is 3-5% by mass. In this state, the film was dried while maintaining an interval at which the stretching ratio in the transverse direction (direction perpendicular to the machine direction) was 3%. Then, it further dried by conveying between the rolls of the heat processing apparatus, and produced the polarizing plate protective film 1 with a thickness of 80 μm.
Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependence of Re was measured, and the optical characteristics were calculated. Re was 1 nm and Rth was 6 nm. I was able to confirm.

<Preparation of polarizing plate A>
Next, iodine is adsorbed on the stretched polyvinyl alcohol film to produce a polarizing film, and a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., Re = 3 nm, Rth = 45 nm) is subjected to a surface saponified film sample. One surface was saponified in the same manner as the surface saponification treatment on the alignment film side in (CFS-01), and the saponified surface was attached to one surface of the polarizing film using a polyvinyl alcohol-based adhesive.

  Next, using the polyvinyl alcohol adhesive, the produced film (CAO-102) was subjected to saponification treatment in the same manner as the surface saponification treatment on the alignment film side in the surface saponification film sample (CFS-01) on the CAF-102 side. The cellulose acetate film of the polarizing film is bonded so that the CAF-102 side subjected to saponification treatment is the polarizing film side and the transmission axis of the polarizing film is parallel to the slow axis of the first retardation region A polarizing plate A was formed on the non-coated side.

<Preparation of polarizing plate C>
In the same manner, a polarizing film was prepared, and a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was applied to one side in the same manner as the surface saponification treatment on the alignment film side in the surface saponified film sample (CFS-01). Saponification treatment was performed, and the saponification surface was attached to one surface of the polarizing film using a polyvinyl alcohol-based adhesive. In the same manner, the polarizing plate protective film 1 manufactured as described above was attached to the other side of the polarizing film to form a polarizing plate C.

A pair of polarizing plates provided in a liquid crystal display device (LCD-AD172-CWA, manufactured by I / O Data Equipment Co., Ltd.) using an IPS type liquid crystal cell is peeled off, and one of the retardations in the first retardation region is removed. The phase axis is parallel to the rubbing direction of the liquid crystal cell (that is, the slow axis of the first retardation region is parallel to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display), and The polarizing plate A was attached so that the second retardation region surface side was the liquid crystal cell side.
Subsequently, the polarizing plate C is attached to the other side of the IPS type liquid crystal cell so that the polarizing plate protective film 1 side is on the liquid crystal cell side and the polarizing plate A is in a crossed Nicol arrangement. A display device was produced. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.06%. Moreover, the IPS type liquid crystal display device of the present invention produced as described above was a good image display in which no unevenness was observed on the black display screen.

Next, an example of a polarizing plate with an antireflection function is shown.
[Example 13]
<Production of polymer film>

(Preparation of cellulose acylate stock solution)
A cellulose acylate stock solution (original dope solution) having the following composition was prepared. In the dissolution, raw materials were put into a mixing tank and stirred while heating to dissolve each component.

(Cellulose acylate stock solution (original dope solution) composition)
Cellulose acylate stock solution composition (parts by mass) Original dope solution I Original dope solution II
Cellulose triacetate 100 100
(Acetylation degree 60.7% (6-position substitution degree 0.90)
Triphenyl phosphate (plasticizer) 7.8 2
Biphenyl diphenyl phosphate (plasticizer) 3.9 1
The following UV agent U-1 1 1
The following UV agent U-2 1 1
Methyl acetate 290 320
Methanol 25 30
Acetone 25 30
Ethanol 25 30
1-butanol 12 12

UV agent

(Preparation of Retardation Adjuster Solution (RE-3))
11.6 parts by mass of the following retardation adjusting agent, 77 parts by mass of methyl acetate, 6.6 parts by mass of methanol, 6.6 parts by mass of acetone, 6.6 parts by mass of ethanol, and 3.2 parts by mass of 1-butanol are mixed. The solution was put into a tank and stirred while heating to prepare a retardation adjusting agent solution (RE-3).

Retardation adjuster

(Preparation of cellulose acylate dope solution for inner layer and outer layer)
The following composition was added to the mixing tank with stirring in the order of the retardation preparation solution (RE-3) and the following fine particle dispersion (RL-2) with respect to the original dope solution, and stirred and mixed for the inner layer. A cellulose acylate dope solution for the outer layer was prepared. The addition amounts of the retardation adjusting agent and the fine particle dispersion with respect to 100 parts by mass of cellulose acylate are as shown below.
The obtained dope was filtered at 50 ° C. with a filter having an absolute filtration accuracy of 0.01 mm (manufactured by Toyo Roshi Kaisha, Ltd., # 63) and a filter having an absolute filtration accuracy of 0.0025 mm (manufactured by Pall, FH025).

(Cellulose acylate dope composition)
Dope formulation for each layer (part by mass) Dope solution A for inner layer Dope solution A for outer layer
Original dope solution I 482 −
Original dope solution II-473
Retardation adjusting agent solution (RE-3) 72 26
Fine particle dispersion (RL-2) 9 10.2

(Fine particle dispersion (RL-2) composition)
Hydrophobic silica 2.00 parts by mass Product name "AEROSIL R812"
Modified methyl group, primary particle size 7 nm: manufactured by Nippon Aerosil Co., Ltd. Cellulose triacetate 2.00 parts by mass Acetic acid degree 60.7% (6-position substitution degree 0.90)
Dispersant (DP-1) 0.25 parts by mass Methyl acetate 78.70 parts by mass Methanol 14.20 parts by mass 1-butanol 2.86 parts by mass

Dispersant DP-1
C ₁₂ H ₂₅ (CH ₂ CH ₂ O) ₄ PO (OH) ₂

  Using a three-layer co-casting die, the filtered dope was placed so that the inner layer dope was on the inside and the outer layer dope was on both sides, and the layers were cast using a band casting machine. The same band casting machine as in Example 1 was used. The dope discharge amount was adjusted so that the inner layer thickness was 48 μm and both outer layer thicknesses were 6 μm, the casting and drying conditions were the same as in Example 1, and the stretching ratio was 16% using a tenter and stretched. The cellulose acylate film (CAF-103) in the form of a wound roll having a length of 3000 m and a width of 1.2 m was produced by maintaining the subsequent width at 130 ° C. for 30 seconds. Re was 14 nm and Rth was 80 nm.

(Characteristic evaluation of polymer film)
Each characteristic of the obtained cellulose acylate film (CAF-103) was evaluated in the same manner as in Example 1, and the results are shown in Table 5.

<Alkali saponification treatment>
After passing the above film (CAF-103) through a dielectric heating roll having a temperature of 70 ° C. and raising the film surface temperature to 45 ° C., a 0.8 mol / Kg potassium hydroxide solution is formed on the inner surface of the film. (Solvent: Isopropyl alcohol / propylene glycol / water = 75/13/12% by mass) An alkaline solution (surface tension at 35 ° C., 16 mN / m, viscosity at 35 ° C., 4.2 mPa) was added to an mL using an extrusion coater. After coating with m ² and heating at 45 ° C. for 10 seconds, an alkali diluted solution (35 ° C.) composed of IPA / acetone solution / water (1/1/18 parts by mass) is used on the wet coated surface using a rod coater. The primary cleaning was performed by applying a surface tension of 40 mN / m). Primary cleaning liquid remaining amount at this time (the coater secondary side, indicating the amount of liquid re-coated mixed alkali solution on the polymer film) was 1.4 mL / m ^2. Immediately after that, washing using a rod coater to apply washing water at 25 ° C. (residual amount of the washing solution is 1.4 mL / m ² ) is performed three times in succession, and dried for 5 seconds with hot air at 100 ° C. A saponified film (CFS-103) was produced.
The obtained film surface had a contact angle with water of 33 °, the P change in the width direction (difference between the maximum value and the minimum value) was 0.001, and the surface shape was excellent with no unevenness. .

<Preparation of optical compensation sheet>
An optical compensation sheet was prepared using a saponified film (CFS-103) as a transparent support.
(Formation of alignment film)
On the saponification surface of the transparent support (CFS-103), an alignment film coating solution (O-3) having the following composition was coated with a # 14 wire bar coater, heated at 60 ° C. for 60 seconds, and further 90 The film was dried for 160 seconds with warm air at 0 ° C. to produce a long roll-shaped transparent support provided with an alignment film. When the prepared alignment film was observed by SEM of a cross section of the prepared sample, the average of the three films was 0.7 μm in thickness. Next, rubbing treatment was performed in a direction in which the angle formed with the slow axis direction of the long roll-shaped transparent support provided with the alignment film was 45 °.

(Alignment film coating solution (O-3) composition)
The following modified polyvinyl alcohol 19 parts by mass The following carboxylic acid compound (A-2) 0.075 parts by mass Water 360 parts by mass Methanol 120 parts by mass Glutaraldehyde 1 part by mass

Modified polyvinyl alcohol (average degree of polymerization: 3500-4000)

Carboxylic acid compound (A-2)

(Formation of optically anisotropic layer)
A discotic liquid crystal coating liquid (DA-3) having the following formulation was prepared in a SUS tank.

(Composition of optically anisotropic layer coating liquid (DA-3))
The following discotic liquid crystalline molecules (DLC-C) 42 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass Cellulose acetate butyrate (CAB551-0.2, yeast) 0.92 parts by mass Cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co.) 0.23 parts by mass The following fluorine-containing compound (F-2) 4.2 parts by mass Photopolymerization initiator 40 parts by mass (Irgacure-907, manufactured by Ciba Geigy)
Sensitizer 0.45 parts by mass (Kayacure-DETX, manufactured by Nippon Kayaku Co., Ltd.)
Methyl ethyl ketone 111 parts by mass

Discotic liquid crystalline molecules (DLC-C)

Fluorine-containing compound (F-2)

On the alignment film formed on the transparent support, the coating solution was applied with a # 3 wire bar. This was heated in an aging zone at 130 ° C. for 2 minutes to align the discotic liquid crystal molecules. Next, UV irradiation was performed for 1 minute using a 120 W / cm high-pressure mercury lamp at 130 ° C. to polymerize the discotic liquid crystal molecules. Then, it stood to cool to room temperature. Thus, an optical compensation sheet (CFO-103) having an optically anisotropic layer was produced. When the produced optically anisotropic layer was observed by SEM through a cross section of the produced sample, the average thickness was 1.3 μm.
When the performance of the obtained sheet was examined in the same manner as in Example 2, good performance equivalent to that of the optical compensation sheet (CFO-02) of Example 2 was obtained.

<Preparation of polarizing plate>
(Preparation of polarizing film (HF-03))
The PVA film was immersed in an aqueous solution of 2.0 g / L of iodine and 4.0 g / L of potassium iodide at 25 ° C. for 240 seconds, and further immersed in an aqueous solution of boric acid 10 g / L at 25 ° C. for 60 seconds, followed by tenter stretching. The film was introduced into a machine, stretched 5.3 times, and thereafter, the width was kept constant and dried in an atmosphere at 80 ° C. while shrinking, and then separated from the tenter and wound up. The moisture content of the PVA film before starting stretching was 31%, and the moisture content after drying was 1.5%.
The difference in transport speed between the left and right tenter clips was less than 0.05%, and no wrinkles or film deformation was observed at the tenter outlet.
The obtained polarizing film had a transmittance at 550 nm of 43.7% and a polarization degree of 99.97%.

(Preparation of antireflection film)
An outer surface in the roll form of FUJITAC (TD80U, manufactured by Fuji Photo Film Co., Ltd.) is subjected to alkali saponification treatment in the same manner as the surface saponification film (CFS-103), and a support on which one side is made hydrophilic is obtained. Obtained. The contact angle with water per 1 m ² of the hydrophilic surface of the support is 33 to 35 °, and the amount of P change in the width direction (difference between the maximum value and the minimum value) is 0.003. The shape was uniform and not cloudy.
Next, a low refractive index layer coating solution having the following formulation is stirred and prepared, filtered through a polypropylene filter having a pore size of 1 μm, and then coated on the non-hydrophilized side of the support prepared above with a bar coater. After drying at 80 ° C. for 5 minutes, the polymer was crosslinked by heating at 120 ° C. for 10 minutes to form a low refractive index layer having a thickness of 0.1 μm, and an antireflection film was produced.

(Low refractive index layer coating solution composition)
210 parts by mass of heat-crosslinkable fluorine-containing polymer (JN-7228, solid content concentration 6%, manufactured by JSR Corporation)
18 parts by mass of silica sol (MEK-ST) (average particle size 10-20 nm, solid content concentration 30% by mass, manufactured by Nissan Chemical Co., Ltd.)
200 parts by mass of methyl ethyl ketone

  The cellulose acylate film (CAF-103) side (opposite side of the optical compensation layer) of the optical compensation sheet (CFO-103) having the optically anisotropic layer prepared as described above is the alignment film of the film (CAF-103). The same hydrophilic treatment as that on the forming side was performed. This and the antireflection film produced above were applied to each hydrophilic cellulose triacetate side with a polyvinyl alcohol-based adhesive material having a thickness of about 30 μm, and bonded to both sides of the polarizing film (HF-03). A polarizing plate was produced by drying at 0 ° C.

<Production of liquid crystal display device>
A pair of polarizing plates provided in a liquid crystal display device using an OCB type liquid crystal cell (VT23XD1, manufactured by Nanao Co., Ltd.) is peeled off, and the polarizing plate prepared above is replaced with an optical compensation sheet (CFO-103). A liquid crystal display device in a bend alignment mode, in which the rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing it are anti-parallel through an adhesive so as to be on the liquid crystal cell side Was made.
{Evaluation of LCD devices}
A white display voltage of 2 V and a black display voltage of 6 V were applied to the liquid crystal cell of this liquid crystal display device, and the front contrast ratio was measured using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). Further, the viewing angle (angle range where the contrast ratio is 10 or more) in the left-right direction (the direction orthogonal to the cell rubbing direction) was examined.
The liquid crystal display device of the present invention has an excellent front contrast ratio of 200 and a viewing angle of 160 °, and has a good contrast and a wide viewing angle. In addition, it was confirmed that the liquid crystal display device had excellent display quality with no cloudiness or foreign matter on the surface.

Claims (20)

Washing the alkaline solution present on the polymer film with water or an alkaline washing liquid containing water and an organic solvent,
The method for alkali saponification of a polymer film, wherein the washing step is performed using a roll coater or a rod coater. Applying an alkaline solution to a polymer film having a temperature of room temperature or higher,
Washing the alkaline solution present on the polymer film with water or an alkaline washing liquid containing water and an organic solvent,
The method for alkali saponification of a polymer film, wherein the washing step is performed using a roll coater or a rod coater. Applying an alkaline solution to a polymer film having a temperature of room temperature or higher,
Maintaining the temperature of the polymer film above room temperature,
Washing the alkaline solution present on the polymer film with water or an alkaline washing liquid containing water and an organic solvent,
The method for alkali saponification of a polymer film, wherein the washing step is performed using a roll coater or a rod coater. Heating the polymer film to room temperature or higher in advance,
Applying an alkaline solution to the polymer film;
Maintaining the temperature of the polymer film above room temperature,
Washing the alkaline solution present on the polymer film with water or an alkaline washing liquid containing water and an organic solvent,
The method for alkali saponification of a polymer film, wherein the washing step is performed using a roll coater or a rod coater. [1] The reapplying amount of the diluted alkaline solution on the polymer film on the secondary side of the roll coater or rod coater in the step of washing the alkaline solution is 4 mL / m ² or less, and [2] By the alkali saponification method The alkali saponification method according to any one of claims 1 to 4, wherein the amount of change in the width direction when the amount of phosphorus element on the surface of the obtained polymer film is measured by ESCA is smaller than 0.005.   The method for alkali saponification of a polymer film according to any one of claims 1 to 5, wherein the total number of roll coaters or rod coaters in the washing step is 2 to 10.   The alkali saponification method according to claim 1, wherein each step is carried out while the polymer film is conveyed.   The alkali saponification method according to claim 7, wherein the polymer film is continuously conveyed. The alkali saponification method according to claim 1, wherein the hydroxide ion concentration of the alkaline solution is 0.1 to 5 mol / kg, and the coating amount is 1 to 50 mL / m ² .   The alkali agent of the alkali solution is an alkali metal hydroxide, the solvent of the alkali solution is an alcohol having 8 or less carbon atoms, a ketone having 6 or less carbon atoms, an ester having 6 or less carbon atoms, and the number of carbon atoms. The alkali saponification method according to any one of claims 1 to 9, which comprises one or more organic solvents selected from polyhydric alcohols of 6 or less and water.   The alkaline solution contains at least one surfactant selected from nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants. The alkali saponification method described.   The alkali saponification method according to claim 11, wherein the concentration of the surfactant is 0.001 to 10% by mass. 13. The alkali saponification method according to claim 11 or 12, wherein the surfactant is a nonionic surfactant represented by the following general formula (1):
General formula (1) R1-L1-Q1
[Wherein R1 represents an alkyl group having 8 or more carbon atoms (simple or modified), L1 represents a single bond or a divalent linking group connecting R1 and Q1, and Q1 represents a polyoxyethylene unit (polymerization) Degree 5 to 150), represents a nonionic hydrophilic group selected from a polyglycerin unit (degree of polymerization 3 to 30) and a hydrophilic sugar chain unit].   14. The alkali saponification according to claim 1, wherein the alkaline solution has a surface tension of 45 mN / m or less (35 ° C.) and a viscosity of 0.8 to 20 mPa · s (35 ° C.). Method.   The alkali saponification method according to claim 1, wherein the polymer film is a cellulose acylate film.   A surface saponified cellulose acylate film obtained by the alkali saponification method according to claim 15.   An optical film comprising the surface saponified cellulose acylate film according to claim 16.   A polarizing plate comprising the optical film according to claim 17.   A liquid crystal display device comprising the polarizing plate according to claim 18.   20. The liquid crystal display device according to claim 19, wherein the display mode is any one selected from TN, IPS, VA, and OCB.