KR20050001402A - Optical compensation sheet, polarizing plate, and liquid crystal display device - Google Patents

Abstract

PURPOSE: An optical compensation sheet is provided to optically compensate a liquid crystal cell and is arranged at a polarizing plate to prevent light leakage from occurring in an LCD device, thereby improving display quality. CONSTITUTION: An optical compensation sheet is made of a cellulose acylate film. The cellulose acylate film has a retardation value(Re) of 0nm<=Re<20nm within an area and a thickness d of 10§­<d<85§­. The cellulose acylate film has an average value(Vmin+Vmax) of 2.2km/sec<(Vmin+Vmax)/2<2.5km/sec obtained by a minimum value(Vmin) and a maximum value(Vmax) of sound speed measured within the area. A minimum to maximum value ratio(Vmax/Vmin) of the sound speed measured within the area is 1.01<Vmax/Vmin<1.12. The retardation value is defined as follows; Re=(nx-ny) xd, wherein nx is a refractive index in a slow axis direction within the area of the cellulose acylate film and ny is a refractive index in a fast axis direction within the area of the cellulose acylate film. If not specially defined, light has a wavelength of 550nm.

Description

Optical Compensation Sheet, Polarizing Plate, and Liquid Crystal Display {OPTICAL COMPENSATION SHEET, POLARIZING PLATE, AND LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to an optical compensation sheet for improving the viewing angle of a liquid crystal display device, a polarizing plate using the same, and a liquid crystal display device.

A liquid crystal display device usually consists of a liquid crystal cell, a polarizing plate and an optical compensation sheet (phase difference plate). In a transmissive liquid crystal display device, two polarizing plates are attached to both sides of a liquid crystal cell, and one or two optical compensation sheets are arranged between the liquid crystal cell and the polarizing plate. In the reflective liquid crystal display device, the reflecting plate, the liquid crystal cell, one optical compensation sheet, and one polarizing plate are arranged in this order.

The liquid crystal cell is generally composed of a rod-like liquid crystalline molecule, two bases for encapsulating it, and an electrode layer for applying a voltage to the rod-like liquid crystalline molecule. Due to the difference in the alignment state of the rod-like liquid crystalline molecules, the liquid crystal cell has a twisted nematic (TN), an in-plane switching (IPS), a ferroelectric liquid crystal (FLC), an optically-competent bend (OCB), and an STN (transfer-type). Various display modes have been proposed for Super Twisted Nematic (VA), Vertically Aligned (VA), and reflective types such as HAN (Hybrid Aligned Nematic).

A polarizing plate generally consists of a polarizing film and a transparent protective film, and this polarizing film is generally obtained by impregnating polyvinyl alcohol with the aqueous solution of iodine or a dichroic dye, and then uniaxially stretching this film. It is set as the structure which attached two transparent protective films to the both sides of this polarizing film.

Optical compensation sheets are used in various liquid crystal display devices in order to eliminate image coloring or to enlarge a viewing angle.

When using an optical compensating sheet, there is a problem in that a liquid crystal display becomes thick. However, by using a polarizing plate (ellipse polarizing plate) in which one transparent protective film of the polarizing plate also functions as an optical compensating sheet (retardation film), the display can be made without thickening the liquid crystal display. It is proposed to improve the quality (for example, to increase the front contrast) (see, for example, Japanese Patent Laid-Open No. Hei 1-68940).

Optical anisotropy (high retardation value) is required for the optical compensation sheet (retardation film) of the liquid crystal display device. Therefore, as the optical compensation sheet, it is common to use a synthetic polymer film having a high retardation value such as a polycarbonate film or a polysulfone film.

Apart from an optical compensation sheet made of a synthetic polymer film, an optical compensation sheet having an optically anisotropic layer formed of discotic liquid crystalline molecules on a transparent support has also been proposed (for example, Japanese Patent Laid-Open No. 3-9325, Japanese Patent Application Laid-Open Nos. 6-148429, 8-505206, 9-26572, and Japanese Patent No. 2640083 (European Patent Application Publication No. 646820), US Pat. 5583679 specification), 33118197 specification (US Pat. No. 5,525,525, European Patent Application Publication No. 774683), International Publication No. 96/37804 pamphlet (Japanese Patent Application Laid-open No. Hei 8-327822, European Patent) Patent Application Publication No. 0783128, US Patent No. 6124913), International Publication No. 96-31793, Japanese Patent Application Laid-Open No. H11-316378 (US Patent No. 604457), Japanese Patent Application Laid-Open No. 9-21914 Reference). The high retardation value required for the optical compensatory sheet is achieved by the optically anisotropic layer. In contrast, the cellulose ester film is usually used because the transparent support requires high optical isotropy (low retardation value).

As described above, in the technical field of optical materials, a synthetic polymer film is used when optical anisotropy (high retardation value) is required for the polymer film, and a cellulose acetate film is used when optical isotropy (low retardation value) is required. It was a general principle.

European Patent Application Publication No. 0911656A2 discloses a cellulose acetate film having a high retardation value, which can be used for applications requiring optical anisotropy, overcoming conventional principles. It is described that a liquid crystal display device with high display quality is obtained by inserting this cellulose acetate film as a protective film of a polarizing film between this polarizing film and a liquid crystal cell.

The optical compensation sheet is deformed by heat and tends to cause a phase difference, which causes problems in durability. When frame-like optical leakage (raise of transmittance) occurs in the liquid crystal display device due to the generated phase difference, the display quality of the liquid crystal display device is reduced.

In order to solve the problem of retardation caused by deformation, it is proposed to use an optical compensation sheet having an optically anisotropic layer formed of a discotic (disc) compound coated on a transparent support as a protective film of a polarizing plate (for example, See European Patent Application Publication No. 0911656A2 and Japanese Patent Application Laid-open No. Hei 7-191217).

The optical compensatory sheet is usually formed by forming an alignment film on the transparent support or directly rubbing it thereon, then applying a coating liquid containing a liquid crystal compound and forming an optically anisotropic layer to form a monodomain of the liquid crystal compound. It is produced through a complicated and long manufacturing process, such as fixing orientation by photopolymerization. When manufacturing in a wide elongated roll state through these manufacturing processes, the optical characteristics such as optical anisotropy of the transparent support itself should be uniform, and there should be no stains or the like on the surface of the coating film applied on the support. It is important for uniformity. On the other hand, even if it is produced in a wide roll state, the entire surface is made uniform optical property, and the axial shift angle of the slow axis of a support body and the extending | stretching direction of a film is suppressed in order to improve the deviation of a viewing angle (Japanese Patent Laid-Open No. 2003- 66230 and the like), or to define a standard deviation value of the slow axis angle (Japanese Patent Laid-Open No. 2003-22943 or the like) has been proposed.

In recent years, the size of liquid crystal displays has increased rapidly. With the increase in size of the liquid crystal display device, the problem which has been solved in the prior art is brought to the present again. For example, when a polarizing plate using a conventional optical compensation sheet as a protective film was attached to a liquid crystal display device comprising a large panel of 17 inches or larger, light leakage due to thermal deformation was confirmed again. For this reason, there is a demand for an optical compensatory sheet having excellent visibility with no variation in display characteristics such as an in-plane viewing angle even when the screen size is increased.

It is reported that the problem of light leakage can be solved by reducing the thickness of the transparent support of the optical compensation sheet (see, for example, Japanese Unexamined Patent Publication No. 2002-169023).

Although the thinning of the transparent support is strongly desired in order to meet the demand for low cost due to the weight reduction and the productivity improvement, the thin film thickness has caused a problem in practical use especially in the case where the strength is lowered and used in a large liquid crystal display device. This problem has not been sufficiently solved in the conventional proposal, and it is strongly desired to increase the strength of the support. However, if the strength of the support is simply increased, the optical properties deteriorate and the visibility decreases.

Moreover, in the liquid crystal display device which consists of a large panel of 20 inches or more, the problem which was not examined at all by the prior art was confirmed. And the light by thermal deformation was confirmed again.

In order to solve the problem caused by thermal deformation, the optical compensation sheet is required to be excellent in durability against the change of the use environment as well as the function of optically compensating the liquid crystal cell.

An object of the present invention is to optically compensate a liquid crystal cell using an optical compensation sheet.

Another object of the present invention is to improve the display quality of a liquid crystal display device by arranging the optical compensation sheet on one side of the polarizing film and using it in the liquid crystal display device without causing problems such as light leakage.

Another object of the present invention is to add an optical compensation function to a polarizing plate without increasing the number of components of the polarizing plate.

Another object of the present invention is to provide an excellent optical compensation sheet having a thin layer and a light weight, sufficient mechanical properties of the film, excellent visibility, and no variation in viewing angle magnification even in a large screen size.

Another object of the present invention is to provide an optical compensation sheet having high productivity without variation in viewing angle magnification even when manufactured in a wide elongated roll form.

Further, another object of the present invention is to provide a polarizing plate and a liquid crystal display device excellent in visibility using an excellent optical compensation sheet having a thin layer and light weight and no variation in viewing angle magnification characteristics.

In addition, an object of the present invention is to provide an optical compensation sheet which can be used as a protective film for a polarizing plate using a cellulose acetate film as a component, and which can add an optical compensation function to the polarizing plate without increasing the number of components in the polarizing plate. To provide.

Another object of the present invention is to provide a polarizing plate in which the optical compensation sheet is used as a protective film and in which the productivity does not decrease in the processing step of the polarizing plate.

Still another object of the present invention is to provide a liquid crystal display device in which the polarizing plate is provided and the liquid crystal cell is optically compensated.

(Means to solve the task)

The present invention provides the following optical compensation sheet, a polarizing plate, a liquid crystal display device and a method for producing a cellulose acylate film.

(1) An optical compensation sheet comprising a cellulose acylate film, wherein the cellulose acylate film is

(Iii) the in-plane retardation value Re is 0 nm ≤ Re <20 nm,

(Iii) the thickness d is 10 µm <d <85 µm,

(Iii) The average ((Vmin + Vmax) / 2) of the minimum value (Vmin) and the maximum value (Vmax) of the sound velocity measured in the film plane is 2.2 km / sec <(Vmin + Vmax) / 2 <2.5 km / sec,

(Iii) The ratio (Vmax / Vmin) of the maximum value to the minimum value of the sound velocity measured in the film plane is 1.01 < Vmax / Vmin < 1.12, the optical compensation sheet (first embodiment).

In-plane retardation value Re is defined by following formula (I).

(I) Re = (nx-ny) × d

In the formula, nx is a refractive index in the slow axis direction in the cellulose acylate film plane; ny is a refractive index in the fast axis direction in the cellulose acylate film plane; and d is the thickness (unit: nm) of the cellulose acylate film. In addition, when not specifically defined, the wavelength of the light used for a measurement is 550 nm.

In addition, in this specification, a "slow axis" means the direction in which a refractive index becomes largest, and a "fast axis" means the direction in which a refractive index becomes a minimum.

In-plane retardation value Re of the cellulose acylate film used for the 1st aspect of this invention satisfy | fills following formula (VII).

0 nm ≤ Re <20 nm

The thickness (d) of the cellulose acylate film used for the 1st aspect of this invention satisfy | fills following formula.

(Iii) 10 μm (= 10000 nm) <d <85 μm (= 85000 nm)

As for the cellulose acylate film used for the 1st aspect of this invention, the average ((Vmin + Vmax) / 2) of the minimum value (Vmin) and the maximum value (Vmax) of the sound velocity measured in the film plane satisfy | fill the following formula (i). .

2.2 //sec<(Vmin+Vmax)/2<2.5 sec / sec

In the formula, Vmin is the sound velocity in the direction in which the speed of sound is minimized in the surface of the cellulose acylate film; Vmax is the sound velocity in the direction in which the speed of sound is maximized in the surface of the cellulose acylate film. Unless otherwise specified, measurements are made using a plurality of frequencies in the range of 10 Hz to 100 MHz.

In the cellulose acylate film used in the present invention, the ratio (Vmax / Vmin) of the maximum value (Vmax) to the minimum value (Vmin) of the sound velocity measured in the film plane satisfies the following equation.

(V) 1.01 <Vmax / Vmin <1.12

In the formula, Vmin is the sound velocity in the direction in which the speed of sound is minimized in the surface of the cellulose acylate film; Vmax is the sound velocity in the direction in which the speed of sound is maximized in the surface of the cellulose acylate film.

(2) An optical compensation sheet comprising an cellulose acylate film and an optically anisotropic layer formed of a liquid crystalline compound, wherein the cellulose acylate film is

(Iii) the in-plane retardation value Re is 0 nm ≤ Re <20 nm,

(Iii) the thickness d is 10 µm <d <85 µm,

(Iii) The average ((Vmin + Vmax) / 2) of the minimum value (Vmin) and the maximum value (Vmax) of the sound velocity measured in the film plane is 2.2 km / sec <(Vmin + Vmax) / 2 <2.5 km / sec,

(Iii) The ratio (Vmax / Vmin) of the maximum value to the minimum value of the sound velocity measured in the film plane is 1.01 < Vmax / Vmin < 1.12, the optical compensation sheet (second embodiment).

(3) The optical compensation sheet according to (1) or (2), wherein the cellulose acylate film has a retardation value in the thickness direction in the range of (ii) 70 to 400 nm.

The retardation value Rth in the thickness direction is defined by the following formula (II).

(II) Rth = {(nx + xy) / 2-nz} × d

Where nx is a refractive index in the slow axis direction in the cellulose acylate film plane; ny is a refractive index in the fast axis direction in the cellulose acylate film plane; nz is a refractive index in the thickness direction of the cellulose acylate film; and d is a cellulose acyl It is thickness (unit: nm) of a rate film. In addition, when not specifically defined, the wavelength of the light used for a measurement is 550 nm. It is preferable that the retardation value Rth of a thickness direction of the cellulose acylate film used for a 1st aspect or 2nd aspect of this invention satisfy | fills following formula (ii).

(Ii) 70 nm <Rth <400 nm

(4) The optical compensation sheet as described in (1) or (2) whose cellulose acylate film is a cellulose acetate film.

(5) The optical compensation sheet according to (4), wherein the cellulose acylate film is made of cellulose acetate having an acetylation degree in a range of 59.0 to 61.5%.

(6) The optical compensation sheet according to (1) or (2), wherein the cellulose acylate film contains an aromatic compound having at least two aromatic rings.

(7) The optical compensation sheet as described in (6) containing 0.01-20 mass parts of aromatic compounds which have at least 2 aromatic ring with respect to 100 mass parts of cellulose acylates.

(8) The optical compensation sheet according to (6), wherein the aromatic compound has at least one 1,3,5-triazine ring.

(9) An optical compensation sheet comprising, in this order, an anti-corrosion film and an optically anisotropic layer laminated on a transparent support having a film thickness of at least 20 µm and not greater than 80 µm, each containing fine particles having an average primary particle diameter of 80 nm or less.

Arithmetic mean roughness (Ra) of surface irregularities based on JIS B0601-1994 on the alignment film side surface of the transparent support is 0.0002 µm or more and 0.1 µm or less, 10-point average roughness (Rz) is 0.0002 µm or more and 0.3 µm or less Height Ry is 0.002 micrometer or more and 0.5 micrometer or less,

The value of Re defined by formula (I), (II) of the transparent support is 2 nm or more and 200 nm or less, and the value of Rth is 50 nm or more and 400 nm or less, The optical compensation sheet (3rd term | claim) mode).

(I) Re = (nx-ny) × d

(II) Rth = {(nx + ny) / 2-nz}

[Wherein nx is the refractive index in the slow axis direction in the plane of the transparent support; ny is the refractive index in the fast axis direction in the plane of the transparent support; nz is the refractive index in the thickness direction of the transparent support; and d is the thickness of the transparent support.]

(10) The average spacing (Sm) of surface irregularities based on JIS B0601-1994 on the alignment film side surface of the transparent support is 0.001 µm or more and 5 µm or less, and the arithmetic mean roughness Ra and the ten point average roughness ( The ratio (Ra / Rz) of Rz) is 0.1 or more and 1 or less, The optical compensation sheet as described in (8) characterized by the above-mentioned.

(11) The transparent support is a long product having a length of 100 m or more and 5000 m or less and a width of 0.7 m or more and 2 m or less, a curl in the width direction of -10 / m to + 10 / m and based on JIS K7128-2: 1998. The tear strength is 2 g or more, The optical compensation sheet as described in said (8) characterized by the above-mentioned.

(12) The said transparent support body is the absolute value of the in-plane average of the slow-axis angle of 0 degree | times or more and 3 degrees or less, and the standard deviation of the slow-axis angle is 0 degree | times or more and 1.5 degrees or less, as described in said (8) characterized by the above-mentioned. Optical compensation sheet.

(13) The transparent support is composed of a cellulose acylate film containing at least one cellulose acylate in the range of 55.0 to 62.5% of acetylation degree, the fine particles and an aromatic compound having at least two aromatic rings, respectively. The optical compensation sheet as described in said (8).

(14) The optical compensation sheet according to the above (13), wherein the aromatic compound has at least one 1,3,5-triazine ring.

(15) The transparent support is a cellulose acylate film that is just produced by a solution casting method having a casting step. The metal support casting the dope of the casting step has an arithmetic mean roughness Ra of the surface of 0.001 μm. It is 0.015 micrometer or less, and the 10-point average roughness Rz of the surface is 0.001 micrometer or more and 0.05 micrometer or less, The optical compensation sheet as described in said (8) characterized by the above-mentioned.

(16) that the arithmetic mean roughness Ra and the maximum height Ry of the surfaces of the alignment support and the opposite side of the transparent support are three times or less the arithmetic mean roughness Ra and the maximum height Ry of the alignment film layer surface, respectively. The optical compensation sheet as described in said (8) characterized by the above-mentioned.

(17) The transparent support is a cellulose acylate film, and the cellulose acylate film is a solution preparation step of dissolving cellulose acylate in a substantially non-chlorinated solvent to prepare a cellulose acylate solution, and a cellulose acylate solution as a cellulose acylate solution. The optical compensation sheet as described in said (8) characterized by the above-mentioned. It is a film manufactured by the film manufacturing process of film-forming a late film, and the extending process of extending | stretching a cellulose acylate film.

(18) The substantially non-chlorine solvent comprises a mixed solvent of at least one organic solvent selected from ethers, ketones, esters having 3 to 12 carbon atoms and an alcohol, and the ratio of alcohol in the total solvent is It is an optical compensation sheet as described in said (17) characterized by the range of 2-40 mass%.

(19) The optical support sheet according to (8), wherein the transparent support is surface-treated with an alkaline solution containing at least a water-soluble organic solvent having a boiling point of 60 to 120 ° C and a surfactant and / or a compatibilizer. To provide.

(20) The optical compensation sheet according to any one of (1), (2), (13), (15) and (17), wherein the cellulose acylate is cellulose acetate.

(21) The optical compensation sheet according to (9), wherein the optically anisotropic layer consists of a liquid crystal compound.

(22) An optical compensation sheet (fourth aspect), comprising a cellulose acetate film having an acetylation degree of 59.0 to 61.5%, the surface being saponified, and having a contact angle of water on the surface of 30 ° or more and 70 ° or less.

(23) an optically anisotropic layer composed of a liquid crystalline compound on one side of the cellulose acetate film support having an acetylation degree of 59.0 to 61.5%, and the other side of the support was saponified, and the contact angle of water on the surface was 30 An optical compensation sheet (fifth aspect), characterized by being at least 70 °.

(24) The optical compensation sheet according to (22) or (23), wherein the cellulose acetate film contains 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings with respect to 100 parts by mass of cellulose acetate.

(25) The optical compensation sheet according to (24), wherein the aromatic compound has at least one 1,3,5-triazine ring.

(26) The Re retardation value defined by the following formula (I) of the cellulose acetate film is 5 to 100 nm, and the Rth retardation value defined by the following formula (II) is 70 to 400 nm. The optical compensation sheet as described in said (22).

Equation (I): Re = (nx-ny) × d

Equation (II): Rth = {(nx + ny) / 2-nz} × d

[Wherein nx is the refractive index in the slow axis direction in the film plane; ny is the refractive index in the fast axis direction in the film plane; nz is the refractive index in the thickness direction of the film; and d is the thickness (nm) of the film.]

(27) The optical compensation sheet according to any one of (2), (21) and (23), wherein the liquid crystal compound is a discotic liquid crystalline compound.

(28) A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films uses the optical compensation sheet described in any one of (1), (2) and (9) above. Polarizing plate.

(29) The polarizing plate according to (28), wherein the transmission axis of the polarizing film and the slow axis of the transparent protective film are substantially vertical or parallel.

(30) A polarizing plate composed of a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films is the optical compensation sheet according to (22) or (23), and the optical compensation sheet is saponification treatment of the support. The surface is arrange | positioned so that it may be the polarizing film side, The polarizing plate characterized by the above-mentioned.

(31) The polarizing plate according to (30), wherein the transmission axis of the polarizing film and the slow axis of the transparent protective film are substantially vertical or parallel.

(32) A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein the polarizing plate consists of a polarizing film and two transparent protective films disposed on both sides thereof, wherein the two liquid crystal display devices are disposed between the liquid crystal cell and the polarizing film. At least one of the transparent protective films used the optical compensation sheet in any one of said (1), (2), (9), (22), and (23), The liquid crystal display device characterized by the above-mentioned.

(33) The liquid crystal display device according to (32), wherein the liquid crystal cell is a liquid crystal cell in any one of TN mode, VA mode, MVA mode, n-ASM mode, and OCB mode.

(34) A method for producing a cellulose acylate film in which a cellulose acylate solution is flexible on a metal substrate and peeled off from a metal substrate, followed by drying, wherein the residual volatile content of the cellulose acylate film after peeling is 100 to 45%. A method for producing a cellulose acylate film, which is dried for 10 to 1000 seconds with a warm air of from 160 ° C.

(35) The method for producing an optical compensation sheet according to the above (9), wherein the transparent support is a cellulose acylate film and the cellulose acylate film is produced by a solution casting method having a casting step to produce the transparent support.

The metal support which casts the dope of the said casting process has the arithmetic mean roughness Ra of the surface of 0.001 micrometer or more and 0.015 micrometer or less, and the 10 point average roughness Rz is 0.001 micrometer or more and 0.05 micrometer or less, It is characterized by the above-mentioned. Method for producing an optical compensation sheet.

(The best mode for carrying out the invention)

In the present specification, "(numerical value 1) to (numerical value 2)" and "(numerical value 1) to (numerical value 2)" represent the meanings of "(numerical value 1) or more (numerical value 2) or less", respectively.

(1st aspect, 2nd aspect)

[Retardation of Cellulose Acylate Film]

In this invention, the Re retardation value of a cellulose acylate film is adjusted to the range of 0 nm <Re <20 nm. Preferably it is 0 nm <Re <10 nm, More preferably, it is 0 nm <Re <5 nm.

It is preferable to adjust the Rth retardation value in the range of 70 nm <Rth <400 nm.

When two optically anisotropic cellulose acylate films are used for the liquid crystal display device, the Rth retardation value of the film is preferably in the range of 70 nm <Rth <250 nm, and is in the range of 75 nm <Rth <150 nm. It is more preferable.

When using one optically anisotropic cellulose acylate film for the liquid crystal display device, the Rth retardation value of the film is preferably in the range of 150 nm <Rth <400 nm, and in the range of 160 nm <Rth <250 nm. It is more preferable.

Moreover, it is preferable that birefringence ((DELTA) n: nx-ny) of a cellulose acylate film exists in the range of 0.00-0.002. Moreover, it is preferable that birefringence {(nx + ny / 2-nz} of the thickness direction of a cellulose acylate film exists in the range of 0.001-0.04.

And it is preferable that the wavelength dependences A = Δn (450) / Δn (550) and B = Δn (650) / Δn (550) of the birefringence of the cellulose acylate film are 0.20 <A <1.05 and 1.00 <B <1.55 Do.

[Prevention of light leakage]

In order to prevent light leakage due to thermal deformation of the liquid crystal display device, the thickness and elastic modulus of the cellulose acylate film are adjusted.

The thickness d of a cellulose acylate film shall be 10 micrometers <d <85 micrometers. The thinner the thickness (d) of the cellulose acylate film, the thinner it is, but more preferable, but from the viewpoint of manufacturing handling, 30 µm <d <80 µm is preferable.

In general, in order to reduce the virtual deformation, it is preferable to biaxially stretch the cellulose acylate film to increase the surface orientation of the polymer molecules or to set the hygroscopic expansion coefficient to 30 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient of the cellulose acylate film is more preferably 15 × 10 ^-5 /% RH or less, and most preferably 10 × 10 ^-5 /% RH or less. As a method of suppressing the hygroscopic expansion coefficient, there is a method of increasing the density of a cellulose acylate film.

It is preferable that it is 3000 Mpa or less, and, as for the elasticity modulus of a cellulose acylate film, it is more preferable that it is 2500 Mpa or less.

Adjusting the sound velocity so as to satisfy the above-mentioned (i) and (i) is also advantageous from the viewpoint of adjustment of elastic modulus, density, or manufacturing handling.

As for the average ((Vmin + Vmax) / 2) of the minimum value (Vmin) and the maximum value (Vmax) of the sound velocity measured in the film plane of a cellulose acylate film, 2.3 <((Vmin + Vmax) / 2) <2.4 is more preferable. As for the ratio (Vmax / Vmin) of the maximum value with respect to the minimum value of the sound velocity measured in the film plane, 1.03 <Vmax / Vmin <1.10 is more preferable.

[Cellulose Acylate]

Cellulose acylate is an ester of cellulose and acid. The acid is preferably a carboxylic acid, more preferably a fatty acid, still more preferably a fatty acid having 2 to 4 carbon atoms, and most preferably acetic acid (cellulose acetate).

Particular preference is given to cellulose acetate having an acetylation degree in the range of 59.0 to 61.5%. The degree of acetylation means the amount of bound acetic acid per cellulose unit mass. Acetylation degree is based on the measurement and calculation of the acetylation degree in ASTM: D-817-91 (test methods, such as a cellulose acetate).

It is preferable that it is 250 or more, and, as for the viscosity average degree of polymerization (DP) of a cellulose acylate, it is more preferable that it is 290 or more.

Moreover, it is preferable that the cellulose acylate used for this invention has a narrow molecular weight distribution of Mm / Mn (Mm is mass mean molecular weight, Mn is number average molecular weight) by gel permeation chromatography. It is preferable that the value of specific Mm / Mn exists in the range of 1.0-1.7, It is more preferable to exist in the range of 1.3-1.65, It is most preferable to exist in the range of 1.4-1.6.

[Retardation synergist]

In order to adjust the retardation of a cellulose acylate film, the aromatic compound which has an at least 2 aromatic ring is used as a retardation increasing agent.

An aromatic compound is used in 0.01-20 mass parts with respect to 100 mass parts of cellulose acylate. It is preferable to use an aromatic compound in 0.05-15 mass parts with respect to 100 mass parts of cellulose acylate, and it is more preferable to use in 0.1-10 mass parts. You may use together 2 or more types of aromatic compounds.

Aromatic rings of aromatic compounds include aromatic hetero rings in addition to aromatic hydrocarbon rings. It is particularly preferred that the aromatic compound has at least one 1,3,5-triazine ring.

Specific examples of the retardation synergist are described in Japanese Patent Laid-Open No. 2002-169023.

By the retardation control by the retardation increasing agent, the sound speed can be controlled in an appropriate range without involving deformation such as stretching.

(Third aspect)

The optical compensation sheet of the present invention is obtained by laminating an alignment film and an optically anisotropic layer in this order on a transparent support having a specific film thickness containing fine particles having a specific particle size, wherein the transparent support has a specific surface shape and optical characteristics. It features.

<Transparent support>

It is preferable that the transparent support body of this invention is a transparent polymer film. The transparent support preferably has a light transmittance of 80% or more and a haze of 3% or less. As an example of the polymer which comprises a polymer film, a cellulose ester (for example, mono, di, or triacylate body of cellulose), norbornene-type polymer, etc. are mentioned. As this norbornene-type polymer, an aton and zeonex (all are brand names) are mentioned. In addition, even in a polymer which is easily known to express birefringence such as polycarbonate or polysulfone, which is known in the art, it is possible to control the expression of birefringence by modifying molecules as described in the International Publication No. 00/26705 pamphlet. Can be used. These blend polymers, graft polymers, etc. may be sufficient and two or more types can be used.

The said specific film thickness of the transparent support body of this invention is 20-80 micrometers, Preferably it is 30-80 micrometers, More preferably, it is 40-65 micrometers. If the film thickness is less than 20 µm, sufficient strength will not be expressed. If the thickness is greater than 80 µm, the film thickness is insufficient from the viewpoint of weight and handleability.

The variation in the film thickness is preferably within ± 3%, more preferably within ± 2%, and most preferably within ± 1.5%. Within this fluctuation, a good one does not substantially affect the optically anisotropic layer of the support thickness.

The transparent support for use in the present invention can provide a long and wide support by stably obtaining good optical characteristics such as thinning the optical compensation sheet, the polarizing plate, and the liquid crystal display device, and increasing the transmittance to improve contrast and display brightness. Good handling can be handled.

In particular, a polymer film made of cellulose ester is preferably used as the transparent support used in the present invention.

Cellulose which is a raw material of the cellulose ester includes cotton linter, kelpner, wood pulp (softwood pulp, softwood pulp) and the like, but in the present invention, cellulose esters obtained from any raw cellulose can be used, and may be mixed and optionally used. do.

In the present invention, cellulose acylate formed by esterification from cellulose is preferably used, but the above-described particularly preferred cellulose can not be used as it is, but the above-described linter, kelpner, and pulp are used after purification.

In the present invention, cellulose acylate refers to a fatty acid ester of cellulose, with lower fatty acid esters of cellulose being more preferred.

Lower fatty acid means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate). As the cellulose ester, cellulose acetate is preferable, and examples thereof include diacetyl cellulose, triacetyl cellulose and the like. Preference is also given to using mixed fatty acid esters such as cellulose acetate propionate or cellulose acetate butyrate.

Generally, the 2,3,6 hydroxyl groups of a cellulose acylate are not distributed evenly by 1/3 of total substitution degree, and there exists a tendency for the substitution degree of a 6-position hydroxyl group to become small. In this invention, it is preferable that substitution degree of the 6-position hydroxyl group of a cellulose acylate is the same or many compared with 2, 3 positions.

It is preferable that the hydroxyl group at the 6th position is substituted with 30% or more and 40% or less acyl group with respect to the total substitution degree, and it is preferable that it is 31% or more, especially 32% or more.

The 6-position hydroxyl group may be substituted with a propionyl group, a butyloyl group, a valeroyl group, a benzoyl group, an acryloyl group, or the like which is an acyl group having 3 or more carbon atoms in addition to the acetyl group. Substitution degree measurement of each position can be calculated | required by NMR method etc.

As a polymer film used for the transparent support of this invention, the film using the cellulose acylate whose acetylation degree is 55.0-62.5% is preferable, and the film using the cellulose acylate which is 57.0-61.5% is more preferable. The degree of acetylation herein means the amount of bound acetic acid per unit mass of cellulose. Acetylation degree is calculated | required according to the measurement and calculation of the acylation degree in ASTM: D-817-91 (test methods, such as a cellulose acetate).

Moreover, it is preferable that it is 250 or more, and, as for the viscosity average degree of polymerization (DP) of cellulose acylate, it is more preferable that it is 290 or more. Moreover, it is preferable that a polymer film is small in polydispersity index Mw / Mn (Mw is mass mean molecular weight, Mn is number average molecular weight) measured by gel permeation chromatography, and its molecular weight distribution is narrow. As a specific value of Mw / Mn, it is preferable that it is 1.0-2.5, It is more preferable that it is 1.0-2.0, It is most preferable that it is 1.0-1.6.

[Particulates]

The fine particles are added to the transparent support used in the present invention in order to improve the strength of the transparent support and to satisfactorily maintain curl suppression, transportability, adhesion prevention in roll form, or scratch resistance of the film.

The said specific particle diameter of the said microparticles | fine-particles is 80 nm or less in average primary particle diameter, Preferably it is 5-80 nm, More preferably, it is 5-60 nm, Especially preferably, it is 8-50 nm. If the average primary particle diameter exceeds 80 nm, the surface smoothness of the transparent support is impaired.

In particular, it is preferable that the particle size dispersion degree of the said microparticles | fine-particles is similar, and it is more preferable that the particle | grains of particle size 500nm or more do not exist. By using such ultrafine particles, the dispersibility in the dispersion is stabilized, the mechanical properties of the film produced are not impaired, the haze is suppressed low, and the surface irregularities are fine and the irregularities are preferable.

It is preferable that Mohs' Hardness of microparticles | fine-particles is 2-10. More preferably, it is 2.5-10.

The fine particles are not particularly limited as long as the material exhibits the functions described above, and any inorganic compound or organic compound may be used, and a preferred embodiment is a compound containing silicon, silicon dioxide, titanium oxide, or oxide as an inorganic compound. Zinc, aluminum oxide, barium oxide, zirconium oxide, strontium oxide, antimony oxide, tin oxide, tin oxide and antimony, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, calcium hydrate silicate, aluminum silicate, magnesium silicate and phosphoric acid Calcium etc. are preferable, More preferably, it is an inorganic compound and zirconium oxide containing silicon.

Moreover, since the dispersibility to the cellulose acylate of the surface-treated inorganic fine particle is favorable, it is preferable. Specifically, inorganic fine particles that are surface modified with hydrophobicity are preferable.

For example, Hiroaki Yanagida, Supervision of Participation Technology for Part 2 of the Participation Engineering System, Chapter 9 (Fuji Techno Systems, 2002), Kagami City, Hayashi Akira supervised "Manufacture and Application of High Purity Silica" And those described in (CMC, published in 1999).

As an organic compound, polymers, such as a crosslinked polystyrene, a silicone resin, a fluororesin, and an acrylic resin, are preferable, for example, A silicone resin is used preferably especially. It is preferable to have a three-dimensional network structure especially among silicone resin.

0.01-0.3 mass parts is preferable, and, as for the addition amount of the said microparticles with respect to the raw material polymer of the said polymer film, 0.05-0.2 mass part is more preferable with respect to 100 mass parts of polymers.

[Retardation Adjuster]

The polymer film used as the transparent support in the present invention contains, as a retardation regulator, a compound that absorbs ultraviolet rays having a wavelength (λ max) that gives an absorption maximum of the ultraviolet absorption spectrum of the solution from a wavelength of shorter than 400 nm in terms of optical anisotropy. It is preferable. Examples of such a compound include ultraviolet absorbers such as phenylsalicylic acid, 2-hydroxybenzophenones, benzotriazoles, and triphenylphosphate. Moreover, aromatic compounds, triphenylene compounds, discoid compounds (compounds containing a 1,3,5-triazine skeleton, a porphyrin skeleton in a molecule, etc.) having at least two aromatic rings are also preferable. It is preferable that the compound used for the said retardation regulator in this invention does not have absorption in a visible light area substantially.

Aromatic compounds having at least two aromatic rings

As the retardation regulator, an aromatic compound having at least two aromatic rings (hereinafter referred to as "aromatic compound A") is particularly preferably used.

The aromatic ring of the aromatic compound A may be an aromatic hetero ring in addition to the aromatic hydrocarbon ring. It is particularly preferred that the aromatic hydrocarbon ring is a 6 membered ring (ie benzene ring). Aromatic hetero rings are generally unsaturated hetero rings. It is preferable that an aromatic hetero ring is a 5-membered ring, a 6-membered ring, or a 7-membered ring, and it is more preferable that it is a 5-membered ring or a 6-membered ring. Aromatic hetero rings generally have the largest number of double bonds. The hetero atom is preferably a nitrogen atom, an oxygen atom and a sulfur atom, and particularly preferably a nitrogen atom.

It is preferable that it is 2-20, and, as for the number of the aromatic rings which aromatic compound A has, it is more preferable that it is 2-12. In the case of having three or more aromatic rings, the three-dimensional coordinates of at least two aromatic rings may not be steric hindrance. The bonding relationship between two aromatic rings can be classified into (a) forming a condensed ring, (b) directly connecting to a single bond, and (c) bonding through a linking group (since they are aromatic rings, spiro bonds). Cannot form). From the viewpoint of the retardation raising function, any of (a) to (c) may be sufficient. Specifically, the thing of the content described in Unexamined-Japanese-Patent No. 2002-131537 Paragraph No. [0016]-[0023] is mentioned. In addition, in the case of said (b) or (c), it is preferable not to steric hindrance of the three-dimensional coordinate of two aromatic rings.

As aromatic compound A, the rod-shaped compound which has the linear molecular structure of the same content as described in Unexamined-Japanese-Patent No. 2002-363343-[0031]-[0031], Unexamined-Japanese-Patent No. 2000-111914 Paragraph No. ] Compounds containing two aromatic rings having stereoscopic hindered three-dimensional coordinates as described in the above, 1,3 5-triazine compound or porphyrin skeleton containing at least one aromatic ring as a substituent The compound which has a (the compound of Unexamined-Japanese-Patent No. 2001-166144) is mentioned.

In particular, 1,3,5-triazine compound which contains at least one aromatic ring as a substituent is preferable (the triazine ring becomes another aromatic ring). Specifically, the 1,3,5-triazine compound described in General formula (I) of Unexamined-Japanese-Patent No. 2001-166144 Paragraph No. is mentioned.

You may use the said aromatic compound A individually or in mixture of 2 or more types of compounds mentioned above.

Content of aromatic compound A selects and uses the kind of compound for retardation regulators, and the usage-amount in order to adjust to desired retardation. It is preferable to use it in the range of 0.01-30 mass parts with respect to 100 mass parts of said polymers from the point which does not produce the problem of the solubility in the transparent support preparation, insolubilization or precipitation in film manufacture, when manufacturing a transparent support body, It is more preferable to use in the range of 0.1-25 mass parts.

[Plasticizer]

It is preferable to add a conventionally known plasticizer to the transparent support to improve the mechanical properties of the film or to improve the drying speed. As a plasticizer, phosphoric acid ester, carboxylic acid ester (as carboxylic acid, aliphatic carboxylic acid, oxycarboxylic acid (citric acid, malic acid, etc.), aromatic carboxylic acid (phthalic acid, etc.) etc. are mentioned, for example. And the compounds described in JP-A-2001-1745 (published on March 15, 2001, Invention Association) p.16, etc. In addition, esterified compounds of alkanpolyols with carboxylic acids (Japan The compound of Unexamined-Japanese-Patent No. 11-124445, Unexamined-Japanese-Patent No. 2001-247717, etc.) etc. are mentioned preferably.

It is preferable that it is 0.05-25 mass parts with respect to 100 mass parts of said polymers, and, as for the addition amount of a plasticizer, it is more preferable that it is 1-20 mass parts.

[Other additives]

The transparent support may further include an ultraviolet inhibitor (for example, a hydroxybenzophenone compound, a benzotriazole compound, a salicylic acid ester compound, a cyanoacrylate compound, and the like), a deterioration inhibitor (for example, an antioxidant and a peroxide). A disintegrating agent, a radical inhibitor, a metal deactivator, an acid trapping agent, a light stabilizer (hindered amine, etc.), a release agent, an antistatic agent, etc. may be added.

As for these details, the material described in detail in the above-mentioned Air No. 2001-1745 p.17-22 is preferably used.

In this invention, it is preferable that the said transparent support body consists of a cellulose acylate film containing at least 1 sort (s) of the cellulose acylate, the said microparticles, and the said aromatic compound A in the range of 55.0-62.5% of acetylation degree. At this time, addition of an additive other than the plasticizer to the cellulose acylate film is not particularly limited.

The blending ratio of cellulose acylate, fine particles and aromatic compound A in the cellulose acylate film is the same as the blending ratio described above.

[Characteristics (Surface Shape) of Transparent Support]

The optical compensation sheet of the present invention is characterized in that the transparent support has a specific surface shape. Hereinafter, the surface shape of the transparent support which is a feature of the present invention will be described.

The arithmetic mean roughness Ra of the surface irregularities of the film based on JIS BO601-1994 is 0.0002 µm or more and 0.1 µm or less, and the 10-point average roughness Rz is 0.0002 µm or more and 0.3 µm. And the maximum height Ry is 0.002 µm or more and 0.5 µm or less, preferably the arithmetic mean roughness Ra is 0.0002 µm or more and 0.08 µm or less, and the 10-point average roughness Rz is 0.0002 µm or more and 0.1 µm or less, and Maximum height Ry is 0.002 micrometer or more and 0.5 micrometer or less, More preferably, arithmetic mean roughness Ra is 0.0002 micrometer or more and 0.015 micrometer or less, 10 point average roughness Rz is 0.002 micrometer or more and 0.05 micrometer or less Maximum height Ry is 0.002 micrometer or more and 0.05 micrometer or less, Especially preferably, arithmetic mean roughness Ra is 0.001 micrometer or more and 0.010 micrometer or less, 10 point average roughness Rz is 0.002 micrometer or more and 0.025 micrometer or less, Furthermore, Maximum height Ry is 0.002 micrometer or more and 0.04 micrometer or less.

Within this range, a uniform alignment film without coating unevenness is formed.

In addition, it is preferable that the ratio (Ra / Rz) of the arithmetic mean roughness Ra and the 10-point average roughness Rz in the form of fine surface irregularities is 0.1 or more and 1 or less, and the surface of the film based on JIS B0601-1994. It is preferable that the average spacing Sm of unevenness | corrugation is 0.001 micrometer or more and 5 micrometers or less. Here, the relationship between Ra and Rz represents the uniformity of surface irregularities. More preferably, the ratio (Ra / Rz) is 0.15 or more and 1 or less, particularly preferably 0.17 or more and 1 or less, and the average interval Sm is 0.001 µm or more and 1 µm or less.

The concave and convex shapes of the surface can be evaluated by a transmission electron microscope (TEM), an atomic force microscope (AFM), or the like.

(Other surface shape)

Moreover, the arithmetic mean roughness Ra and the maximum height Ry of the surface on the opposite side to the alignment film side of the transparent support body of this invention are three times or less of the arithmetic mean roughness Ra and the maximum height Ry of the alignment film side surface. It is preferable. More preferably, it is 1-2 times, Especially preferably, it is 1-1.5 times. In such a range, transparency of a film, adhesiveness in roll form, etc. become favorable.

(Long)

The transparent support is preferably a long product. 100 m or more and 5000 m or less are preferable, and, as for the length, 300 m or more and 4500 m or less are more preferable. 0.7 m or more and 2 m or less are preferable, and, as for the width, 1.0 m or more and 1.7 m or less are more preferable.

[Film Dynamics]

(curl)

It is preferable that it is -10 / m-+ 10 / m, and, as for the curl value of the width direction of the transparent support body used for this invention, it is more preferable that it is -8 / m-+ 8 / m. When the transparent support of the present invention is subjected to a surface treatment, a rubbing treatment, or an alignment film, an optically anisotropic layer, or the like, which is described later, on a wide transparent support, the curling value in the width direction of the transparent support is within the above-mentioned range. The handling of the film is good so that the film is not cut. In addition, the film is strongly in contact with the conveying roll at the edge or the center of the film, so that dust does not occur or foreign matter adheres onto the film, so that the frequency of spot defects and coating streaks of the optical compensation sheet is within the allowable range. You can do it by mine. In addition, by setting the curl in the above-described range, it is possible to reduce irregular failures of colors that are likely to occur when the optically anisotropic layer is provided, and to prevent bubbles from being generated when the polarizing film is attached, which is preferable.

The curl value can be measured according to the measurement method specified by the American National Standards Institute (ANSI / ASCPH 1.29-1985).

(Tear strength)

As described above, the transparent support has a film thickness of 20 to 80 µm and a tear strength of 2 g or more based on the JIS K7128-2: 1998 tear test method (Elmendorf tear method). It is preferable in that it can hold | maintain sufficiently. More preferably, it is 5-25g, More preferably, it is 6-25g. Moreover, in conversion of 60 micrometers, 8g or more is preferable, More preferably, it is 8-15g.

Specifically, 50 mm x 64 mm of sample pieces can be measured using a light load tear strength tester after humidity control for 2 hours on 25 degreeC and 65% RH conditions.

In particular, the curl and tear strength are preferably within the ranges described above when the transparent support obtained by completing a predetermined manufacturing process is a long product having a length of 100 m or more and 5000 m or less and a width of 0.7 m or more and 2 m or less.

(Scratch strength)

Moreover, it is preferable that scratch strength is 1 g or more, It is more preferable that it is 5 g or more, It is especially preferable that it is 10 g or more. By setting it as this range, the flaw resistance and handling property of a film surface are maintained without a problem.

Scratch strength can be evaluated by the load g which can visually confirm a scratch mark by using a sapphire needle with a cone angle of 90 degrees and a tip radius of 0.25 m.

[Hygroscopic Expansion Coefficient of Film]

The transparent support preferably has a hygroscopic expansion coefficient of 30 × 10 ⁻⁵ /% RH or less, more preferably 15 × 10 ⁻⁵ /% RH or less, more preferably 10 × 10 ⁻⁵ /% RH It is especially preferable that it is the following. The smaller the hygroscopic expansion coefficient is, the higher the value is usually 1.0 × 10 ⁻⁵ /% RH or higher. The hygroscopic expansion coefficient represents the amount of change in the sample length when the relative humidity is changed under a constant temperature.

By adjusting the hygroscopic expansion coefficient, it is possible to prevent the light leakage due to the increase in the frame-like transmittance, that is, deformation while maintaining the optical compensation function of the optical compensation sheet.

In the measurement method of the hygroscopic expansion coefficient, a sample having a width of 5 mm and a length of 20 mm is cut out from the produced polymer film, and one end is fixed and hanged under an atmosphere of 25 ° C. and 20% RH (R 0). Next, hang a weight of 0.5 g at the other end and leave for 10 minutes to measure the length (L0). Then, the temperature is kept at 25 ° C., and the length L1 is measured by setting the humidity to 80% RH (R1). The hygroscopic expansion coefficient is calculated by substituting the measurement result in the following equation. The measurement is carried out 10 samples for the same sample and adopts the average value.

Hygroscopic expansion coefficient [/% RH] = {(L1-L0) / L0} / (R1-R0)

[Optical anisotropy of the transparent support]

The transparent support for use in the present invention is characterized by exhibiting specific optical anisotropy. Specifically, the Re retardation value and the Rth retardation value indicating the degree of optical anisotropy defined by the following formulas (I) and (II) are each 2 to 200 nm, preferably 4 to 200 nm, and Rth Is 50-400 nm, Preferably it is 55-350 nm.

(I) Re = (nx-ny) × d

(II) Rth = {(nx + ny) / 2-nz} × d

In Formula (I) and (II), nx is the refractive index of the slow-axis direction (direction in which a refractive index becomes largest) in a film plane.

In formula (I) and (II), ny is the refractive index of the fast-axis direction (direction in which refractive index becomes minimum) in a film plane.

In formula (II), nz is the refractive index of the thickness direction of a film.

In formula (I) and (II), d is the thickness of the film which makes a unit nm.

On the other hand, it is preferable that birefringence ((DELTA) n: nx-ny) of a transparent support body is 0.000015-0.0088 with respect to wavelength 550nm, More preferably, it is 0.00025-0.005. The birefringence {(nx + ny) / 2-nz} in the thickness direction is preferably 0.0006 to 0.02 with respect to the wavelength of 550 nm, and more preferably 0.001 to 0.007.

In particular, as the transparent support of the optical compensation sheet used in the TN mode, the Re retardation value is in the range of 4 to 40 nm, and the Rth retardation value is in the range of 50 to 200 nm, and OCB, HAN, VAN, and homogeneous alignment are preferred. As a support body of the optical compensation sheet used for ECB modes, such as a mode, it is preferable that Re retardation value is 10-70 nm, and Rth retardation value is the range of 70-400 nm.

[Slow axis angle of film]

The slow axis angle in the plane of the transparent support is defined as the angle formed between the slow axis and the reference line using the width direction of the roll-shaped film as a reference line (0 °). The clockwise direction is called +. The absolute value of the slow axis angle (axis misalignment) average value is preferably 0 degrees or more and 3 degrees or less, in that the variation in the viewing angle is improved and the visibility of the display image is improved, and more preferably 0 degrees or more and 2 degrees or less. It is most preferable that they are 0 degrees or more and 1 degrees or less. The direction of the average value of the slow axis angle is defined as the average direction of the slow axis.

The standard deviation of the slow axis angle is preferably 0 degrees or more and 1.5 degrees or less, more preferably 0 degrees or more and 0.8 degrees or less, and most preferably 0 degrees or more and 0.4 degrees or less.

By setting the standard deviation to 0 degrees or more and 1.5 degrees or less, it is possible to prevent the occurrence of "color unevenness" in which the color of the display changes.

(4th aspect, 5th aspect)

[Optical Compensation Sheet]

The optical compensation sheet of the fourth aspect of the present invention comprises an optically anisotropic cellulose acetate film having an acetylation degree of 59.0 to 61.5%, the surface is saponified, and the contact angle of water on the surface is 30 ° or more and 70 ° or less, Preferably, it is an optical compensation sheet of 40 degrees or more and 70 degrees or less.

The optical compensation sheet of the fifth aspect of the present invention has an optically anisotropic layer on one side of the cellulose acetate film support having an acetylation degree of 59.0 to 61.5%, one side of the support is saponified, and the contact angle of water The optical compensation sheet is 30 ° or more and 70 ° or less, preferably 40 ° or more and 70 ° or less.

As described above, the present invention is characterized in that the cellulose acetate film used for the optical compensation sheet is saponified, and the contact angle of water is 30 ° or more and 70 ° or less. When the optical compensation sheet of the present invention is applied to a polarizing plate, this saponification treatment improves the adhesion to the polarizing film, and if the contact angle of water is 30 ° or more, the wettability to water is low. After the water droplets do not remain, the yield is improved. Moreover, when the contact angle of water exceeds 70 degrees, since water will be easy to splash, the attached dirt will not fall easily.

In the optical compensation sheet of 5th aspect, it is preferable to form an oriented film on a cellulose acetate film, and to form the optically anisotropic layer containing a disk compound or a rod-shaped liquid crystal compound thereon. An optically anisotropic layer is formed by orienting a disk-shaped liquid crystal compound or a rod-shaped liquid crystal compound on an alignment film and fixing the alignment state. As described above, in the case of forming the optically anisotropic layer on the cellulose acetate film, in order to secure the adhesion between the cellulose acetate film and the alignment film, it was necessary to form a gelatin undercoat layer therebetween. For example, a gelatin undercoat layer can be made unnecessary by making the contact angle of water into the said range by adding the aromatic compound which has the following at least 2 aromatic ring.

0.1-10 micrometers is preferable and, as for the thickness of an optically anisotropic layer, 0.5-5.0 micrometers is more preferable.

Since the disk liquid compound generally has a large birefringence and has various orientations, it is possible to prepare an optical compensation sheet having optical properties that cannot be obtained in a conventional stretched birefringent film by using a discotic compound. Regarding the optical compensation sheet using the discotic compound, there are described in the specifications of JP-A-6-214116, US Pat. No. 5583679, US Pat. No. 5646703, and West German Patent No. 3911620A1.

[Cellulose acetate film]

As the cellulose acetate film used in the present invention, cellulose acetate having an acetylation degree of 59.0 to 61.5% is used.

Acetylation degree means the amount of bound acetic acid per unit weight of cellulose. The degree of acetylation is according to the measurement and calculation of the degree of acetylation in ASTM D-817-91 (test method such as cellulose acetate).

It is preferable that it is 250 or more, and, as for the viscosity average degree of polymerization (DP) of cellulose acetate, it is more preferable that it is 290 or more.

Moreover, it is preferable that the cellulose acetate used for this invention has a narrow molecular weight distribution represented by Mw / Mn (Mw is a mass normal molecular weight, Mn is a number average molecular weight) by a gel permeation chromatography. As a specific value of Mw / Mn, it is preferable that it is 1.0-5.0, It is more preferable that it is 1.3-3.0, It is most preferable that it is 1.4-2.0.

<Saponification treatment of cellulose acetate film>

In this invention, a saponification process is performed as surface treatment, and a plasma process, a flame process, and an ultraviolet irradiation process are performed as needed.

Saponification treatments include acid saponification treatments and alkali saponification treatments. Plasma treatments include corona discharge treatments and glow discharge treatments. In order to maintain the planarity of a film, in these surface treatments, it is preferable to make the temperature of a cellulose acetate film below glass transition temperature (Tg), specifically 150 degrees C or less.

The alkali saponification treatment is preferably carried out in a cycle in which the cellulose acetate film is immersed in an alkaline solution, neutralized with an acidic solution, washed with water and dried.

Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution. It is preferable that it is 0.1N-3.0N, and, as for the prescribed | prescribed concentration of hydroxide ion in alkaline solution, it is more preferable that it is 0.5N-2.0N. The range of 0-90 degreeC is preferable and, as for the temperature of an alkaline solution, 40-70 degreeC is more preferable.

The corona discharge treatment is performed by applying a high voltage between the electrode and the dielectric roll connected to the high voltage generator to place or move the cellulose acetate film during the corona discharge generated between the electrode and the dielectric roll. In addition, in this specification, the high voltage frequency applied between an electrode and a dielectric roll is described as discharge frequency.

Although the corona discharge treatment is easy to carry out in the air, the treatment apparatus can be treated in a sealed or semi-closed state and filled with another gas or mixed with other gases and air, if necessary. Examples of the gas include nitrogen gas, argon gas and oxygen gas.

In the corona discharge treatment, the discharge frequency is generally 50 Hz to 5000 Hz, more preferably 5 Hz to several hundred Hz. If the discharge frequency is too low in the corona treatment, the discharge becomes unstable, and pinholes are formed in the cellulose acetate film, which is not preferable. In addition, if the discharge frequency is too high, it is not preferable because an additional device for impedance matching is required and the price of the device is high.

In order to improve the normal wettability, it is preferable that the corona discharge treatment of the cellulose acetate film be 0.001 kV · A · min / m 2 to 5 kV · A · min / m 2, and 0.01 kV · A · min / m 2 −1 kV · A · min It is more preferable to set it as / m <2>. It is preferable that it is 0.5-2.5 mm, and, as for the space | interval of an electrode and a dielectric roll, it is more preferable that it is 1.0-2.0 mm.

The glow discharge treatment is performed by applying a high voltage between one or more pairs of electrodes in a low pressure gas and placing or moving the cellulose acetate film during the glow discharge generated between the electrodes.

The pressure of the gas in the glow discharge treatment is generally in the range of 0.005 to 20 Torr, and more preferably in the range of 0.02 to 2 Torr. If the pressure is too low, the surface treatment effect is lowered. If the pressure is too high, excessive current flows and is likely to cause sparks, which may damage the cellulose acetate film. The discharge is generated by applying a high voltage between the metal plates or the metal rods arranged in one or more spaces in the vacuum tank. This voltage can take various values depending on the composition and pressure of the atmosphere gas, and normally within the above pressure range, stable normal glow discharge occurs between 500 and 5000V.

In order to improve adhesiveness, it is preferable to make the range of an applied voltage into 2000-4000V. Moreover, the general discharge frequency is thousands of MHz from direct current | flow, and it is preferable that it is 50 Hz-20 MHz. In order to obtain the desired adhesive strength, the glow discharge treatment of the workpiece is preferably set to 0.01 kV · A · min / m 2 to 5kV · A · min / m 2, and 0.15 kV · A · min / m 2 to 1 kV · A · min / It is more preferable to set it as m <2>.

An ultraviolet irradiation process is performed by irradiating an ultraviolet-ray to a cellulose acetate film. In the ultraviolet irradiation treatment, if the surface temperature of the film rises to around 150 ° C. and there is no problem in performance, a high pressure mercury lamp having a main wavelength of 365 nm can be used as the light source. It is also possible to use an ozoneless type high pressure mercury lamp and a low pressure mercury lamp. Regarding the amount of light to be treated, the adhesion between the film and the layer to be bonded improves as the amount of light to be processed increases. However, a problem arises in that the film is colored and the film is easily torn with the increase in the amount of light. Therefore, when using a high pressure mercury lamp having a primary wavelength of 365 nm, the irradiation light amount is preferably 20 to 10000 (mJ / cm 2), more preferably 50 to 2000 (mJ / cm 2). When using a high pressure mercury lamp whose main wavelength is 254 nm, the amount of irradiation light is preferably 100 to 10000 (mJ / cm 2), and more preferably 300 to 1500 (mJ / cm 2).

The contact angle of water on the surface of the optical compensation sheet (cellulose acetate film) of the present invention is specifically an angle formed by dropping the surface pure water onto the cellulose acetate film and forming a tangent drawn on the droplet at the intersection of the surface of the droplet and the film surface, and the film surface. The angle of the side containing the droplet is measured as the contact angle.

Even when the said saponification process is given to a cellulose acetate film, the problem (problems that peeling with a polarizing film arises in a durability test) may arise in adhesiveness with a polarizing film.

In order to make the contact angle of the water of a protective film surface 30 degrees or more and 70 degrees or less and to improve adhesiveness with a polarizing film, it is preferable to add the following hydrophobic compounds (aromatic compound which has two aromatic rings) to a cellulose acetate film. Do.

<Aromatic compound having two aromatic rings>

An aromatic compound having at least two aromatic rings is used as an additive to adjust the contact angle and the retardation value of the cellulose acetate film. Hereinafter, this compound is also called retardation regulator.

An aromatic compound is used in 0.01-20 mass parts with respect to 100 mass parts of cellulose acetates. It is preferable to use an aromatic compound in the range of 0.05-15 mass parts with respect to 100 mass parts of cellulose acetates, and it is more preferable to use in the range which is 0.1-10 mass parts. You may use together 2 or more types of aromatic compounds.

Aromatic rings of aromatic compounds include aromatic hetero rings in addition to aromatic hydrocarbon rings.

It is preferable that an aromatic compound has high hydrophobicity from a viewpoint of contact angle control.

The aromatic rings (aromatic hydrocarbon rings, aromatic hetero rings) of the aromatic compounds used in the present invention are disclosed in paragraphs [0011] to [0085] of JP 2000-111914 A.

It is preferable that the molecular weight of a retardation increasing agent is 300-800.

<Retardation of Cellulose Acetate Film>

The Re retardation value and Rth retardation value of a film are defined by following formula (I) and (II), respectively.

Equation (I): Re = (nx-ny) × d

Equation (II): Rth = {(nx + ny) / 2-nz} × d

In formulas (I) and (II);

nx is the refractive index of the slow-axis direction (direction in which a refractive index becomes largest) in a film plane.

ny is the refractive index of the fast-axis direction (direction in which a refractive index becomes minimum) in a film plane.

nz is the refractive index of the thickness direction of a film.

d is the thickness of the film whose unit is nm.

In this invention, it is preferable to adjust the Re retardation value of a cellulose acetate film to 5-100 nm, and to adjust the Rth retardation value to 70-400 nm.

When using two optically anisotropic cellulose acetate films (optical compensation sheets) for a liquid crystal display device, it is preferable that the Rth retardation value of a film is 70-250 nm.

When using one optically anisotropic cellulose acetate film (optical compensation sheet) for a liquid crystal display device, it is preferable that the Rth retardation value of a film is 150-400 nm.

Moreover, it is preferable that birefringence ((DELTA) n: nx-ny) of a cellulose acetate film is 0.00025-0.00088. In addition, the birefringence {(nx + ny) / 2-nz} in the thickness direction of the cellulose acetate film is preferably 0.00088 to 0.005.

[Method for Producing Transparent Support and Cellulose Acylate Film]

The manufacturing method of transparent support bodies, such as a cellulose acylate used preferably for the 1st-5th aspect of this invention, is demonstrated.

In this invention, it is preferable to manufacture the said transparent support body by the solution casting | flow_spreading method (solvent-casting method), and in the solution casting | flow_spreading method, it uses the solution (dope) which melt | dissolved polymer (cellulose acylate etc.) in organic solvent, etc. To prepare.

(Solution preparation step)

In the solution casting method, the organic solvent to be used is not particularly limited as long as it is an organic solvent usually used in the solution casting method. For example, the solubility parameter is preferably in the range of 17 to 22. Specifically, chlorides of lower aliphatic hydrocarbons, lower aliphatic alcohols, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, ethers having 3 to 12 carbon atoms, aliphatic hydrocarbons having 5 to 8 carbon atoms, and carbon atoms 6 And 12 aromatic hydrocarbons.

Ethers, ketones and esters may have a cyclic structure. Compounds having two or more of functional groups of ethers, ketones and esters (ie, -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. When the said organic solvent is an organic solvent which has two or more types of functional groups, the carbon atom number should just be in the range of the preferable carbon number mentioned above of the compound which has any one functional group.

Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phentol. It is contained.

Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.

Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.

2-ethoxyethyl acetate, 2-methoxyethanol, and 2-butoxyethanol are contained in the example of the organic solvent which has two or more types of functional groups.

The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. It is preferable that the ratio which the hydrogen atom of a halogenated hydrocarbon is substituted by halogen is 25-75 mol%, It is more preferable that it is 30-70 mol%, It is more preferable that it is 35-65 mol%, It is 40-60 mol% Most preferred. Methylene chloride is a representative halogenated hydrocarbon.

In order to manufacture the cellulose acylate film which concerns on this invention, it is preferable to mix and use two or more types of organic solvents. From the viewpoint of controlling the speed of sound, it is preferable to use three kinds of solvents specifically, methylene chloride, methanol and butanol, methylene chloride is 75 parts by mass to 85 parts by mass, methanol is 15 parts by mass to 25 parts by mass and butanol It is preferable to mix in 0.05 mass part-5 mass parts.

Especially in this invention, it is preferable to use the mixed solvent which mixed two or more types of organic solvent as said organic solvent, Especially preferably, they are three or more types of different mixed solvent, and a 1st solvent has 3-4 carbon atoms. Ketones and esters having 3 to 4 carbon atoms or mixtures thereof, and the second solvent is selected from ketones or acetoacetic acid esters having 5 to 7 carbon atoms, and alcohols or boiling points having a boiling point of 30 to 170 ° C as a third solvent It is preferable to select from these hydrocarbons which are 30-170 degreeC.

In particular, it is cellulose acyl to use a mixed solvent of acetate esters, ketones and alcohols obtained by mixing 20 to 90 mass% of acetate esters, 5 to 60 mass% of ketones and 5 to 30 mass% of alcohols. It is preferable from a viewpoint of the solubility of a rate.

The blending ratio of the alcohols in the mixed solvent is preferably 2 vol% or more and 40 vol% or less, more preferably 3 vol% or more and 30 vol% or less, more preferably 5 vol% or more and 20 vol% in the total solvent. It is as follows.

The alcohols are preferably monoalcohol or dialcohol having 1 to 8 carbon atoms or 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 can be mentioned. These may be added independently, or may mix and add 2 or more types.

In particular, a non-halogen organic solvent system containing no halogenated hydrocarbon, particularly a substantially non-chlorine solvent containing no chlorine atom (hereinafter referred to as "non-chlorine solvent") can be mentioned as a preferred embodiment.

Technically, halogenated hydrocarbons such as methylene chloride can be used without any problem, but from the viewpoint of the global environment and the working environment, it is preferable that the organic solvent contains substantially no halogenated hydrocarbons. "Substantially free" means that the proportion of the halogenated hydrocarbons in the organic solvent is less than 5% by mass (preferably less than 2% by mass). Moreover, it is preferable that no halogenated hydrocarbons, such as methylene chloride, are detected at all from the produced cellulose acylate film.

Non-chlorine solvents used in the present invention are described in, for example, Japanese Unexamined Patent Application Publication No. 2002-146043 Paragraph No. 2002-146045, No. 2002-146045 Paragraph No. Examples of the solvent system can be given.

The non-chlorine solvent is a mixed solvent of at least one organic solvent selected from ethers, ketones and esters having 3 to 12 carbon atoms and an alcohol, and the content of alcohol in the total solvent is 2 to 40% by mass. Mixed solvents are preferred.

As such a mixed solvent, the following are mentioned specifically ,.

Methyl acetate / cyclohexanone / methanol / ethanol (= 70/20/5/5, parts by mass)

Methyl acetate / methyl ethyl ketone / acetoacetic acid methyl / methanol / ethanol (= 50/20/20/5/5, parts by mass)

Acetone / acetoacetic acid methyl / ethanol (75/20/5, parts by mass)

Methyl acetate / acetone / methanol / ethanol / butanol (75/10/5/5/5, parts by mass)

Methyl acetate / 1,4-dioxane / cyclopentanone / methanol / 1-butanol (= 60/20/12/5/3, parts by mass)

Acetone / cyclopentanone / methanol / ethanol (= 60/30/5/5, parts by mass)

1,3-dioxolane / cyclohexanone / methylethylketone / methanol / ethanol (= 55/20/15/5/5, parts by mass)

You may add 0 vol% or more and 10 vol% or less of aromatic or aliphatic hydrocarbons with 5 or more carbon atoms to the said mixed solvent. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene, xylene.

In addition, the dope is preferably 10% by mass or less, more preferably 5% by mass or less of the total amount of the organic solvent, in addition to the organic solvent, in view of improving the transparency of the film or increasing the solubility. As the fluoroalcohol, there may be mentioned, for example, the compounds described in JP-A-8-143709 Paragraph No. 11-60807 Paragraph No. You may use these 1 type or 2 types or more of these fluoro alcohols.

In the present invention, when preparing the dope, an inert gas such as nitrogen gas may be filled in the container. In addition, the viscosity just before the film | membrane manufacture of dope should just be a flexible range at the time of film manufacture, It is preferable to be prepared in the range of 10 ps * s-2000 ps * s normally, Especially 30 ps * s-400 ps * s are desirable.

Regarding the preparation of the dope, the dissolution method is not particularly limited, and may be a room temperature dissolution method or a cooling dissolution method or a high temperature dissolution method, or a combination thereof. About these, Unexamined-Japanese-Patent No. 5-163301, Unexamined-Japanese-Patent No. 61-106628, Unexamined-Japanese-Patent No. 58-127737, Unexamined-Japanese-Patent No. 9-95544, Unexamined-Japanese-Patent No. Japanese Patent Application Laid-open No. Hei 10-95854, Japanese Patent Application Laid-open No. Hei 10-45950, Japanese Patent Application Laid-Open No. 2000-53784, Japanese Patent Application Laid-Open No. 11-322946, and Japanese Patent Application Laid-Open No. 11-322947 Japanese Patent Application Laid-Open No. 2-276830, Japanese Patent Application Laid-Open No. 2000-273239, Japanese Patent Application Laid-Open No. 11-71463, Japanese Patent Application Laid-Open No. 4-259511, Japanese Patent Application Laid-Open No. 2000-273184, Japanese Patent Application Laid-Open The dope preparation method of Unexamined-Japanese-Patent No. 11-323017, Unexamined-Japanese-Patent No. 11-302388, etc. is mentioned, The dissolution method of melt | dissolving the raw material polymer of the transparent support body as described in these publications in an organic solvent is also suitably in this invention. These techniques can be applied. In addition, the cellulose acylate dope solution in the case of using cellulose acylate as a polymer is usually concentrated and filtered, and is described in detail in the above-mentioned Air No. 2001-1745 p.25. Moreover, when melt | dissolving at high temperature, it is most cases more than the boiling point of the organic solvent to be used, and in that case, it is used in pressurized state.

The method of preparing dope is further described.

A cellulose acylate solution can be prepared by a general method. The general method means processing at a temperature of 0 ° C. or higher (room temperature or high temperature). Preparation of the solution can be carried out using a method and apparatus for preparing a dope in a conventional solvent cast method. In the general method, a halogenated hydrocarbon (particularly methylene chloride) may be used as the organic solvent.

The amount of cellulose acylate is adjusted to contain 10-40 mass% in the solution obtained. The amount of cellulose acylate is more preferably 10 to 30% by mass. In the organic solvent (main solvent), you may add the arbitrary additive mentioned later.

A solution can be prepared by stirring a cellulose acylate and an organic solvent at normal temperature (0-40 degreeC). The high concentration solution may be stirred under pressurized and heated conditions. Specifically, the cellulose acylate and the organic solvent are placed in a pressurized container and sealed, and the mixture is stirred while heating to a temperature not lower than the boiling point at the normal temperature of the solvent and not boiling. Heating temperature is 40 degreeC or more normally, Preferably it is 60-200 degreeC, More preferably, it is 80-110 degreeC.

You may put each component in a container, after mixing previously. Moreover, you may inject into a container one by one. The vessel should be configured to allow stirring. The vessel can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may use the vapor pressure rise of a solvent by heating. Or you may add each component under pressure after sealing a container.

When heating, it is preferable to heat from the exterior of a container. For example, a jacket type heating device can be used. Moreover, the whole container can also be heated by providing a plate heater in the exterior of a container, piping, and circulating a liquid.

It is preferable to form a stirring blade inside a container, and to stir using this. It is preferable that the stirring blade is the length which comes to near the wall of a container. It is desirable to form scratch blades at the ends of the stirring blades in order to renew the liquid film of the vessel wall.

Instruments may be provided with instruments such as pressure gauges and thermometers. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling or taken out and cooled using a heat exchanger or the like.

A solution can also be prepared by a cooling solution method. By the cooling dissolution method, the cellulose acylate can be dissolved in an organic solvent which is difficult to dissolve by the usual dissolution method. Moreover, even if it is a solvent which can melt | dissolve a cellulose acylate by a normal dissolution method, there exists an effect that a uniform solution can be obtained quickly by a cooling dissolution method.

In the cooling solution method, the cellulose acylate is slowly added in an organic solvent at room temperature at first.

It is preferable to adjust the amount of cellulose acylate so that it may contain 10-40 mass% in this mixture. The amount of cellulose acylate is more preferably 10 to 30% by mass. In addition, you may add arbitrary additives mentioned later in a mixture.

Next, the mixture is cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). Cooling can be performed, for example in a dry ice methanol bath (-75 degreeC) and the cooled diethylene glycol solution (-30--20 degreeC). This cooling causes the mixture of cellulose acylate and organic solvent to solidify.

The cooling rate is preferably 4 ° C / minute or more, more preferably 8 ° C / minute or more, and most preferably 12 ° C / minute or more. Faster cooling rates are preferred, but 10000 ° C / sec is the theoretical upper limit, 1000 ° C / sec is the technical upper limit, and 100 ° C / sec is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling to the final cooling temperature.

Moreover, when this is heated to 0-200 degreeC (preferably 0-150 degreeC, more preferably 0-120 degreeC, most preferably 0-50 degreeC), a cellulose acylate will melt | dissolve in an organic solvent. An elevated temperature may be left to stand only at room temperature, and may be heated in a warm bath.

The heating rate is preferably 4 ° C / minute or more, more preferably 8 ° C / minute or more, and most preferably 12 ° C / minute or more. The higher the heating rate is, the better, but 10000 ° C / sec is the theoretical upper limit, 1000 ° C / sec is the technical upper limit, and 100 ° C / sec is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating to the final heating temperature.

A homogeneous solution is obtained as mentioned above. Moreover, when melt | dissolution is inadequate, you may repeat operation of cooling and a heating. Whether or not dissolution is sufficient can be judged by visually observing the appearance of the solution.

In the cooling dissolution method, it is preferable to use a sealed container in order to avoid moisture mixing due to condensation during cooling. In addition, in a cooling heating operation, when it pressurizes at the time of cooling and depressurizes at the time of heating, a dissolution time can be shortened. In order to perform pressurization and pressure reduction, it is preferable to use a pressure-resistant container.

In addition, a 20 mass% solution in which cellulose acetate (acetylation degree: 60.9%, viscosity average degree of polymerization: 299) was dissolved in methyl acetate by a cooling dissolution method, according to differential scanning calorimetry (DSC), showed a sol state and a gel in the vicinity of 33 ° C. The pseudo phase transition point of a state exists, and it becomes a uniform gel state below this temperature. Therefore, this solution should be maintained at a temperature above the pseudo phase transition temperature, preferably at a gel phase transition temperature of about + 10 ° C. However, this pseudo phase transition temperature differs depending on the degree of acetylation of the cellulose acetate, the viscosity average polymerization degree, the solution concentration, or the organic solvent used.

The said dope may contain other additives, such as a retardation regulator, a plasticizer, and a ultraviolet absorber as needed. In the case of the third aspect of the present invention, fine particles are further added.

(Additional mixing method of fine particles)

When adding microparticles | fine-particles to a cellulose acylate solution, it is important to disperse | distribute so that coarse particle | grains as mentioned above do not exist or agglomeration, precipitation, etc. do not exist, and a method is not specifically limited if these can be satisfied. The desired cellulose acylate solution can be obtained by either method.

It is preferable to mix and disperse the fine particles in dope after preparing a dispersion liquid separately from the above dope adjustment. For example, the method as shown below is mentioned.

(1) After stirring and mixing a solvent (same as the said organic solvent used for the solution casting method) and microparticles | fine-particles, it makes into a microparticle dispersion with a disperser, and adds and stirs to a dope liquid.

(2) After stirring and mixing the solvent and the fine particles, the dispersion is made into a fine particle dispersion by dispersing, and a small amount of cellulose acylate is added to the solvent to dissolve it by stirring. The fine particle addition liquid obtained by adding and stirring the said fine particle dispersion here is fully mixed with dope liquid by an inline mixer.

(3) A small amount of binder is added to the solvent, followed by stirring to dissolve it. The fine particles are added thereto and dispersed in a disperser to form a fine particle dispersion. The fine particle addition liquid is sufficiently mixed with the dope liquid with an inline mixer. A cellulose acylate etc. are mentioned as a binder, Preferably the cellulose acylate provided to dope is used.

Dispersion can use a conventionally well-known wet dispersion method.

Examples of the media wet dispersion machine include conventionally known ones such as sand grinder mills (eg, pin bead mills), dyno mills, high speed impeller mills, pebble mills, roller mills, attritors, colloid mills, and ball mills. In particular, in order to disperse the oxide fine particles of the present invention into ultrafine particles, sand grinder mills, dyno mills, and high speed impeller mills are preferable.

In order to disperse | distribute to the size of the ultrafine particle which does not contain the coarse particle of the said range, the wet dispersion method using the media of less than 0.8 mm of average particle diameters is preferable. As a medium to be used together with the disperser, by using a medium having an average particle diameter of less than 0.8 mm and an average particle diameter in this range, ultrafine particles having an inorganic particle diameter of 100 nm or less and having a constant particle diameter can be obtained. The average particle diameter of the media is preferably 0.5 mm or less, and more preferably 0.05 to 0.3 mm.

In addition, beads are preferable as a medium used for wet dispersion. Specifically, zirconia beads, glass beads, ceramic beads, steel beads, and the like, and zirconia beads having a diameter of 0.05 to 0.2 mm are particularly preferable in view of durability and ultrafine particleization, such as breakage of beads during dispersion. .

Medialess dispersers include ultrasonic, centrifugal, high pressure, and the like. The high pressure dispersing device preferably has a maximum pressure condition of 9.8 MPa or more inside the apparatus in, for example, a tube diameter of 1 to 2000 µm. More preferably, it is 19.6 MPa or more. In addition, it is preferable that the maximum arrival speed is at least 100 m / sec and the heat transfer speed is at least 420 kJ / hr at that time. As the high pressure dispersing device, there is an ultra high pressure homogenizer (trade name Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer Co., Ltd., as well as a manton-gorin type high pressure dispersing device, for example, an Izumi food machinery homogenizer. And UHN-01 manufactured by Sangwa Machinery Co., Ltd., and the like.

It is also preferable to dispose the filter medium so that the dispersed particles in the dispersion satisfy the above-mentioned monodispersity of their average particle diameter and particle diameter and are finely filtered in the separation treatment with the beads to remove coarse aggregates in the dispersion. . As for the filter medium for microfiltration, 25 micrometers or less of filter particle sizes are preferable. The type of filter medium for fine filtration is not particularly limited as long as it has the above-mentioned performance. Examples thereof include filament type, felt type, and mesh type. The material of the filter medium for finely filtration the dispersion has the above-described performance, and is not particularly limited as long as it does not adversely affect the coating liquid. Examples thereof include stainless steel, polyethylene, polypropylene, nylon, and the like.

Additives other than the above-mentioned microparticles | fine-particles may be contained, for example in the step of mixing a cellulose acylate and a solvent, and an additive may be added after preparing a mixed solution with a cellulose acylate and a solvent. Moreover, you may add and mix just before dope is cast | flow_spread, and it is what is called just before addition, The mixing is used by installing screw-type kneading online. Although mixing of these additives may add the additive itself, it is also a preferable aspect to melt | dissolve previously using a solvent or a binder (preferably cellulose acylate), or to disperse | distribute as needed and to use it as a stabilized solution.

(Membrane manufacturing process)

Next, the manufacturing method of the film using dope is described in this invention. As a method and equipment for producing a polymer film, a conventionally known solution casting membrane production method and a solution casting membrane manufacturing apparatus called a drum type or a bend type which are used for producing a polymer film are used.

When the process of membrane manufacture is demonstrated, the dope (cellulose acylate solution) prepared from the dissolver (pot) is once stored in a storage pot, and the bubble contained in dope is defoamed and finally prepared. The prepared dope is important to remove aggregates and foreign matter by microfiltration. Specifically, the filtration filter is preferably used as small as possible in the pore diameter in a range where components in the dope liquid are not removed. For filtration, a filter having an absolute filtration accuracy of 0.1 to 100 µm is used, and a filter having an absolute filtration precision of 0.1 to 25 µm is preferably used. 0.1-10 mm is preferable and, as for the thickness of a filter, 0.2-2 mm is preferable. In that case, the filtration pressure is preferably 15 kgf / cm 2 or less, more preferably 10 kgf / cm 2 or less, and more preferably 2 kgf / cm 2 or less.

In addition, it is also preferable to perform filtration several times by decreasing the pore diameter of the filter in order for fine filtration.

The type of filter medium for fine filtration is not particularly limited as long as it has the above-mentioned performance. Examples thereof include filament type, felt type, and 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 liquid. Examples thereof include stainless steel, polyethylene, polypropylene, nylon, and the like.

The prepared dope is sent from the dope outlet to the press die through a pressurized metering gear pump capable of metering fluid with high precision, for example, by rotation speed, and the dope is driven endlessly from the slit of the press die. It is uniformly pliable on the metal support of the flexible part, so that a less dry dope film (also called a web) is peeled from the metal support at the peeling point where the metal support is almost round. Both ends of the web to be obtained are clipped and dried in a tenter while maintaining their width, followed by a roll group of a drying apparatus to finish drying, and then wound to a predetermined length with a winder. The combination of the tenter and the drying apparatus of the roll group varies depending on the purpose. In the third aspect of the present invention, the metal support used in the casting step has an arithmetic mean roughness (Ra) of 0.001 µm or more and 0.015 µm or less, and a ten-point average roughness (Rz) of 0.001 µm or more and 0.05 µm or less. It is preferable that it is the following. More preferably, arithmetic mean roughness Ra is 0.001 micrometer or more and 0.01 micrometer or less, and 10 point average roughness Rz is 0.001 micrometer or more and 0.02 micrometer or less. More preferably, the ratio (Ra) / (Rz) is at least 0.15. Thus, by making the surface roughness of a metal support into a predetermined range, the surface shape of a film after film manufacture can be controlled in the range of the 3rd aspect of this invention.

Regarding each of these manufacturing processes (classified as flexible (including co-lead), drying, peeling, stretching, etc.), the processes described in detail in the above-mentioned Air No. 2001-1745 p.25-30 are preferable. In the casting step, one type of dope may be single layer cast, or two or more types of dope formed by dissolving different polymers may be simultaneously and / or sequentially covalently smoked.

In particular, in the process of film-forming from the dope which consists of a composition as mentioned above, a drying process is important so that the added compound may be implemented without aggregation or localization.

Drying of the dope on a support is generally carried out by shooting hot air from the surface side of the support (drum or belt), that is, from the surface of the web on the support, from the back of the drum or belt, from a liquid with temperature control. Is a liquid heat transfer method for controlling the surface temperature by heating the drum or the belt by heat transfer by contacting the back surface of the belt or drum on the opposite side of the dope flexible surface, but the liquid heat transfer method is preferred. The surface temperature of the support before casting may be any number of degrees as long as it is below the boiling point of the solvent used for dope. However, in order to promote drying and to eliminate fluidity on the support, it is preferable to set the temperature at a temperature of 1 to 10 ° C. lower than the boiling point of the solvent having the lowest boiling point among the solvents used.

The drying temperature in the drying process of the polymer film which obtains a polymer film by drying flexible dope on a support body is 30-250 degreeC, especially 40-180 degreeC is preferable. And in order to remove a residual solvent, it is dried at 50-160 degreeC, In that case, it is used preferably by evaporating a residual solvent by drying with the high temperature wind which changed the temperature gradually. The above method is described in JP-A-5-17844. According to this method, it is possible to shorten the time from casting to peeling. The drying temperature, drying air volume and drying time differ depending on the solvent used, and may be appropriately selected depending on the type and combination of solvents used. The residual solvent amount of the final finish film is preferably 2% by mass or less and 0.4% by mass or less in order to obtain a film having good dimensional stability. Moreover, in this invention, since peeling time can be shortened further with a peeling agent, and resistance at the time of peeling becomes low, deterioration of surface shape (protrusions resulting from peeling off the lateral stain at the time of peeling, gel-like protrusions, etc.). Polymer films free of

Specifically, the average drying rate from the casting of the dope to peeling is preferably more than 300 mass% / min and 1000 mass% / min or less, more preferably 400 mass% / min. Moreover, it is preferable to set it as 900 mass% / min or less, Most preferably, exceed 500 mass% / min, and set it as 800 mass% / min or less.

If the average drying rate is 300 mass% / min or less, the film cannot be peeled off at high speed. As a result, productivity may deteriorate. If the average drying rate exceeds 1000 mass% / min, wind unevenness may occur due to dry wind. Since unevenness may arise in planarity and the shape of a surface, it is preferable to carry out in the range mentioned above.

The average drying rate is a value obtained by dividing the amount of change in the solvent content of the cast dope by time.

To adjust the average drying speed, it is possible to use by appropriately adjusting the temperature of the drying air, the air volume, the concentration of the solvent gas, the surface temperature of the flexible support, the temperature of the flexible dope, the wet thickness of the flexible dope, and the solvent composition of the flexible dope. Can be.

And the average drying speed in the range within 15m from the dope's softening point exceeds 300 mass% / min and is 1000 mass% / min or less, Preferably it exceeds 400 mass% / min, and also 900 mass% / It is minutes or less, More preferably, it exceeds 500 mass% / min and is 800 mass% / min or less. The average drying speed is not particularly limited at the position exceeding 15 m from the softening point, but it is preferable to carry out in the same range.

The average drying rate between 3 seconds immediately after calcination and 20 seconds after calcination is more than 300 mass% / min and is 1000 mass% / min or less, preferably more than 400 mass% / min and 900 mass% / min or less More preferably, it exceeds 500 mass% / min and is 800 mass% / min or less. In addition, the average drying speed is not specifically limited in the range exceeding 20 second after casting | flow_spread.

In the drying process after peeling from a support body, a film tries to shrink | contract in the width direction by evaporation of a solvent. Drying at elevated temperatures results in greater shrinkage. Drying while suppressing this shrinkage as much as possible is preferable to improve the planarity of the finished film. In this regard, a method (tenter method) of drying the entire drying process or part of the process as shown in JP-A-62-46625, for example, while supporting both ends of the width of the web with a clip in the width direction is preferable. .

The speed of producing the polymer film also 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 the residual solvent at the time of peeling the web 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 will remain on the belt when peeled, which will interfere with the next casting, and thus the peeling residue should never be present and the peeling force should never be present. This is because a web strength that can withstand this is needed. The amount of residual solvent at the time of peeling also depends on the method of drying on the belt or drum, and the method of heat transfer on the back of the belt or drum rather than by blowing air on the dope surface can effectively reduce the amount of residual solvent.

Specifically, it is preferable to dry on the conditions which become the range of 0.01-1.5 mass% of residual solvent amount in a polymer film. More preferably, it is 0.01-1.0 mass%.

In the casting step, it is preferable that uniaxial stretching in only one direction such as the casting direction (vertical direction) or biaxial stretching in the casting direction and the other direction (horizontal direction) be performed.

In addition, the dope may simultaneously cast other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer, etc.).

In the manufacturing method of the optical compensation sheet of this invention, in the 3rd aspect, the said transparent support body is a cellulose acylate film, The said transparent support body is prepared by film-forming the cellulose acylate film by the solution casting method which has a casting process. It is a manufacturing method of the optical compensation sheet to be manufactured, The metal support which casts the dope of the said casting process has the arithmetic mean roughness (Ra) of the surface of 0.001 micrometer or more and 0.015 micrometer or less, and the 10-point average roughness of the surface (Rz). ) Is 0.001 µm or more and 0.05 µm or less. However, the optical compensation sheet of the present invention is not limited to this manufacturing method, and can be manufactured by various methods.

(Stretching process)

The produced polymer film can further adjust retardation by an extending | stretching process. It is preferable that a draw ratio is 3 to 100%.

When the stretching method of following (1) and / or (2) is employ | adopted, axial shift | offset | difference (ground-axis angle) can be adjusted in a predetermined range.

(1) 3-40%, More preferably, it is extending | stretching to the width direction at the draw ratio of 7 to 38%, More preferably, 15 to 35%. Subsequently, heat treatment is performed at 60 to 160 ° C while inflating 0.4% or more and 5% or less, more preferably 0.7% or more and 4% or less, still more preferably 1% or more and 3.5% or less in the longitudinal direction.

(2) A temperature difference is given to the front and back during stretching. The temperature of the surface that is in contact with the substrate (bend or drum) during casting is set to be 2 ° C or higher and 20 ° C or lower, more preferably 3 ° C or higher and 15 ° C or lower, more preferably 4 ° C or higher and 12 ° C or lower than the opposite surface. .

By this method, localization of the additives (plasticizer, retardation regulator, ultrafine particles, etc.) added into the film in the stretching step is eliminated, so that "axial shift" control is achieved.

In addition, by adjusting the conditions of the stretching treatment, the standard deviation of the slow axis angle of the optical compensation sheet can be reduced. Although there is no limitation in particular in the extending | stretching processing method, The extending | stretching method by a tenter is mentioned as the example. When extending | stretching using a tenter to the film produced by the said solvent cast method, the standard deviation of the film slow-axis angle can be made small by controlling the state of a film after extending | stretching. Specifically, the standard deviation of the slow axis angle can be made small by extending | stretching process which adjusts a retardation value using a tenter, and maintaining the polymer film immediately after extending | stretching below the glass transition temperature of a film as it is. If the temperature of the film at this holding time is equal to or higher than the glass transition temperature, the standard deviation increases.

As described above, in the third aspect of the present invention, the transparent support is a cellulose acylate film, and the cellulose acylate film is a solution in which cellulose acylate is substantially dissolved in a non-chlorine solvent to prepare a cellulose acylate solution. It is preferable that it is a film manufactured by the preparation process, the film | membrane manufacturing process of film-forming a cellulose acylate film from a cellulose acylate solution, and the extending process which extends a cellulose acylate film.

Moreover, the cellulose acetate films of a 4th and 5th aspect can be made into an optically anisotropic film by adjusting retardation by an extending | stretching process. In the fourth aspect of the present invention, it is essential to make the cellulose acetate film optically anisotropic. It is preferable that a draw ratio is 3 to 100%.

In these embodiments, the thickness of the cellulose acetate film is preferably 20 µm to 120 µm, more preferably 30 to 100 µm. Most preferred is 40 to 80 mu m.

And when describing a film | membrane manufacturing method, it is preferable to add the said retardation increasing agent to dope.

The dope is cast on a drum or bend and the solvent is evaporated to form a film. It is preferable to adjust density | concentration so that solid content dope may be 18 to 35% before casting. It is preferable to finish the surface of the drum or bend in the mirror state. Regarding the casting and drying method in the solvent cast method, U.S. Pat.Nos.2336310, 2367603, 2492078, 2492977, 2492978, 2607704, 27,269, 2727070, and British Patent 640731 The specification of each of Unexamined-Japanese-Patent No. 736892, Unexamined-Japanese-Patent No. 45-4554, 49-5614, Unexamined-Japanese-Patent No. 60-176834, 60-203430, 62-115035 is described. .

It is preferable that dope is cast on the drum or bend whose surface temperature is 10 degrees C or less. It is preferable to air and dry for 2 second or more after being soft.

The obtained film can be peeled off from the drum or bend and dried again with warm air, which in turn has changed the temperature from 100 ° C to 160 ° C in a state where the volatile content is 45 to 70%, to evaporate the residual solvent. 45-70% is preferable and, as for the volatile matter after peeling off, 50-65% is more preferable. If the volatile content is less than 45%, the retardation is increased to 2.0 to 30 nm, and if it exceeds 70%, foaming due to evaporation occurs or deformation of the film occurs, which is a problem in any case. 100-160 degreeC is preferable and, as for the temperature of a warm air, 110-140 degreeC is more preferable. If the temperature is less than 100 ° C., the retardation value becomes large. If the temperature exceeds 160 ° C., foaming due to evaporation occurs or deformation of the film occurs, which causes problems.

The obtained film may be peeled off from the drum or bend, and then dried again by hot air whose temperature is sequentially changed to 100 to 160 ° C to evaporate the residual solvent. The above method is described in JP-A-5-17844. According to this method, it is possible to shorten the time from casting to peeling off. In order to carry out this method, it is necessary to gel dope at the surface temperature of the drum or bend at the time of casting.

Using the adjusted cellulose acylate solution (dope), two or more layers can also be cast and can be filmed. In this case, it is preferable to produce a cellulose acylate film by the solvent cast method. The dope is flexible on a drum or bend and evaporates the solvent to form a film. It is preferable to adjust density | concentration so that dope before casting may be in the range of 10 to 40% of solid content. It is preferable to finish the surface of the drum or bend in the mirror state.

When plural cellulose acylate liquids of two or more layers are cast, it is possible to cast a plurality of cellulose acylate solutions, and a solution containing cellulose acylate from a plurality of oil studies formed at intervals in the advancing direction of the support, respectively. A film can be produced while making it flexible and laminating (for example, described in each of Unexamined-Japanese-Patent No. 61-158414, Unexamined-Japanese-Patent No. 1-22419, and 11-198285). In addition, it is also possible to form a film by casting a cellulose acylate solution from two oil studies (for example, JP-A-60-27562, JP-A-61-94724, JP-A 61-947245, JP). 61-104813, 61-158413, and each of Unexamined-Japanese-Patent No. 6-134933. In addition, a method of casting a cellulose acylate film which wraps the flow of the high viscosity cellulose acylate solution with the low viscosity cellulose acylate solution and simultaneously pushes out the high viscosity and low viscosity cellulose acylate solution can also be used (for example, Japanese published) Patent publication No. 56-162617).

Moreover, the method of manufacturing a film by peeling the film shape | molded to the support body by 1st oil research using 2 oil studies, and making a 2nd casting | flexion to the side which contact | connects the support surface (for example, Japanese Patent Publication No. 44-A). 20235) can also be employed.

The same solution may be used for the flexible cellulose acylate solution, and another cellulose acylate solution may be used. In order to give a function to a some cellulose acylate layer, the cellulose acylate solution according to the function may be pushed out from each oil research.

In addition, the cellulose acylate solution of the present invention may be flexible at the same time as other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, an ultraviolet absorbing layer, and a polarizing film).

In the conventional monolayer liquid, it is necessary to push out the high-viscosity cellulose acylate solution at high concentration in order to make the thickness of a required film. In this case, the stability of the cellulose acylate solution was poor, and solids were generated, causing protrusion failure or poor planarity. As a solution to this problem, by casting a plurality of cellulose acylate solutions from oil research, it is possible to simultaneously push out a high viscosity solution onto the support, to produce a planar film with good flatness and excellent cellulose. By using an acylate solution, reduction of dry load can be achieved and the production speed of a film can be raised.

It is preferable to add polyester urethane to a cellulose acylate film in order to improve mechanical properties. Moreover, it is preferable that polyester urethane is a reactant of polyester and diisocyanate represented by following General formula (1), and it is preferable to be soluble in dichloromethane.

(1) H-(-O- (CH ₂ ) l-OOC- (CH ₂ ) m-CO) nO- (CH ₂ ) l-OH

In the formula, l represents an integer of 2 to 4; m represents an integer of 2 to 4; n represents an integer of 1 to 100.

In more detail, the constituent polyesters thereof are ethylene glycol, ethylene glycol, 1,3-propanediol, or 1,4-butanediol, and the dibasic acid component is sockdan hydro consisting of succinic acid, glutaric acid, or adipic acid. It is polyester which has an oxyl group, and the polymerization degree n is in the range of 1-100. Although polymerization degree n should just be in the range of 1-100, the suitable degree of polymerization differs slightly according to the kind of glycol and dibasic acid to be used, and it is especially preferable to become the range of 1000-4500 as a molecular weight of polyester.

Dichloromethane soluble polyester urethane resin is obtained by reaction of polyester of Formula (1) and diisocyanate, and is a compound of a repeating unit represented by Formula (2) in general formula.

(2) CONH-R-NHCO- (O- (CH ₂ ) l-OOC- (CH ₂ ) m-CO) nO- (CH ₂ ) lO)-

In the formula, l represents an integer of 2 to 4; m represents an integer of 2 to 4; n represents an integer of 1 to 100; R represents a divalent atomic group residue.

Examples of the divalent atomic group residues include the following formulas, for example.

Examples of the diisocyanate component used in the polyurethane compound include polymethylene diisocyanates (general formula: ONC- (CH ₂ ) p- represented by ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate. NCO (p represents an integer from 2 to 8), aromatic diisocyanate (e.g. p-phenylene diisocyanate, tolylene diisocyanate, p, p'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate) ) And m-xylylene diisocyanate. Tolylene diisocyanate, m-xylylene diisocyanate, and tetramethylene diisocyanate are preferable because they are easy to obtain, relatively stable, easy to handle, and excellent in compatibility with cellulose acylate when polyurethaneized.

It is preferable that the molecular weight of polyester urethane resin exists in the range of 2000-50000. Molecular weight can be suitably adjusted with the kind or molecular weight of the diisocyanate component which is component polyesters or these linking groups. The molecular weight of the polyester urethane resin is more preferably in the range of 5000 to 15000 from the viewpoint of improving mechanical properties of the cellulose acylate film and compatibility with cellulose acylate.

The synthesis | combination of dichloromethane soluble polyester urethane can be easily obtained by mixing polyester diol and diisocyanate represented by Formula (1), and heating under stirring.

The polyesters represented by the formula (1) include a hot melt condensation method or a acid chloride and glycol of these acids by a polyesterification reaction or transesterification reaction of a corresponding dibasic acid or its alkyl ester with glycols. It can be synthesize | combined easily by any method of the interfacial condensation method with, if it adjusts suitably so that a terminal group may be a hydroxyl group.

Dichloromethane soluble polyester urethane resin is very compatible with the cellulose acylate of 58% or more of acetylation degree. Although slight difference is recognized by the structure of resin, when the molecular weight of polyester urethane is 10000 or less, even if it is 200 mass parts of polyester urethanes with respect to 100 mass parts of cellulose acetates.

Therefore, when the polyester urethane resin is mixed with cellulose acylate and the mechanical properties of the film are to be improved, the content of the polyester urethane resin may be appropriately determined according to the type, molecular weight and desired mechanical properties of the urethane resin.

In order to improve the mechanical properties while maintaining the properties of the cellulose acylate, it is preferable to contain 10 to 50% by mass of the polyester urethane resin relative to the cellulose acylate.

Moreover, this polyester urethane resin does not thermally decompose stably to at least 180 degreeC. These dichloromethane soluble polyester urethanes are particularly compatible with cellulose acylate having an acetylation degree of 58% or more. Therefore, a film having a very high transparency can be obtained by mixing both films. Moreover, since these polyester urethanes have a high average molecular weight, there is little volatility even at high temperature unlike conventional low molecular plasticizers. Therefore, the film | membrane obtained by film-forming from these mixtures has few problems by volatilization and migration of the plasticizer which were seen with the conventional plasticizer in subsequent processing.

By adding polyester urethane to a cellulose acylate film, the fracture strength and tear strength at high temperature and low temperature become large, and the problem that a film tears is eliminated. Conventionally, low molecular weight plasticizers have been used to improve the breaking strength and tear strength of the coating. In this method, although there is some effect in normal temperature and a high humidity state, in a low temperature and high humidity state, the film | membrane softness falls and the result which was not necessarily satisfactory was not obtained. In addition, when attempting to improve the mechanical properties by the low molecular weight plasticizers, it was common that mechanical properties such as tensile strength were significantly lowered with the addition amount of the plasticizer.

When dichloromethane soluble polyester urethane resin is added to cellulose acylate, a slight decrease in tensile strength is observed with the addition amount of the resin, but the decrease in strength is surely small compared with the case of low molecular plasticizer addition, and the addition is not performed. A tough film with a large fracture strength almost equivalent to the case is obtained. In addition, by mixing the polyester urethane, it is possible to prevent the migration of the plasticizer at low temperature and high humidity. Therefore, the film is not bonded to each other and is very flexible, so that the film is transparent and glossy without wrinkles and noises. A film is obtained.

Although it is preferable to add the said polyester urethane to a cellulose acylate film in order to improve mechanical property, the following plasticizer can be used instead of polyester urethane or in combination with polyester urethane. Phosphoric acid ester or carboxylic acid ester is used as a plasticizer. Examples of the phosphoric acid esters include triphenylphosphate (TPP) and tricredil phosphate (TCP). Phthalic acid ester and citric acid ester are typical as carboxylic acid ester. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include O-acetyl citrate triethyl (OACTE) and O-acetyl citrate tributyl (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate ester plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred.

It is preferable that the addition amount of a plasticizer is 0.1-25 mass% of the quantity of a cellulose ester, It is more preferable that it is 1-20 mass%, It is most preferable that it is 3-15 mass%.

A deterioration inhibitor (for example, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid trapping agent, and amine) may be added to the cellulose acylate film. Deterioration inhibitors are described in Japanese Unexamined Patent Publications No. 3-199201, 5-1907073, 5-194789, 5-271471, and 6-107854. It is preferable that it is 0.01-1 mass% of the solution (dope) to prepare, and, as for the addition amount of a deterioration inhibitor, it is more preferable that it is 0.01-0.2 mass%. If the addition amount is less than 0.01% by mass, the effect of the deterioration inhibitor is hardly recognized. When addition amount exceeds 1 mass%, the bleed out (break out) of the deterioration inhibitor to the film surface may be recognized. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

[2-axis stretching]

It is preferable to extend | stretch a cellulose acetate film suitably in order to reduce virtual deformation. Since it is possible to reduce the virtual strain in the stretching direction by stretching, it is more preferable to biaxially stretch to reduce the strain in all directions in the plane. However, it is more preferable to extend so that it may become the sound speed range mentioned above from a manufacturing handling viewpoint.

There are simultaneous biaxial stretching methods and sequential biaxial stretching methods for biaxial stretching, and the sequential biaxial stretching method is preferable from the viewpoint of continuous production, and the film is removed from the bend or drum after the dope is flexible, and then in the width direction (length direction). After extending | stretching, it extends in a longitudinal direction (width direction).

The method of extending | stretching in the width direction is each Unexamined-Japanese-Patent No. 62-115035, Unexamined-Japanese-Patent No. 4-152125, 4-284211, 4-298310, and 11-48271, for example. It is described in. Stretching of the film is performed at room temperature or under heating conditions. It is preferable that heating temperature is below the glass transition temperature of a film. The film can be stretched by treatment during drying, and is particularly effective when a solvent remains. In the case of longitudinal stretching, the film is stretched, for example, by adjusting the conveying roller speed of the film to make the winding speed of the film faster than the peeling speed of the film. In the case of the widthwise stretching, the film can be stretched by conveying while keeping the width of the film in the tenter and gradually widening the width of the tenter. It is also possible to extend | stretch using a drawing machine after film drying (preferably uniaxial drawing using a long drawing machine). The stretching ratio of the film (the ratio of the increase by stretching to the original length) is preferably in the range of 0 to 50%, more preferably in the range of 10 to 40%, and in the range of 15 to 35%. Most preferably.

The process from casting to drying may be in an air atmosphere or in an inert gas atmosphere such as nitrogen gas. The winding machine used for manufacture of a cellulose acylate film should just be used normally. For example, it can be wound by a winding method such as a constant tension method, a constant torque method, a tapered tension method, and a program tension control method having a constant internal stress.

[Hygroscopic expansion coefficient]

The hygroscopic expansion coefficient represents the amount of change in the sample length when the relative humidity is changed under a constant temperature.

In order to prevent the increase in the frame-like transmittance, the hygroscopic expansion coefficient of the cellulose acylate film is preferably 30 × 10 ^-5 /% RH or less, more preferably 15 × 10 ^-5 /% RH or less, Most preferably, it is ^10-5 /% RH or less. In addition, although the moisture absorption expansion coefficient is small, it is usually a value of 1.0x10 <^-5> /% RH or more.

The measuring method of a hygroscopic expansion coefficient is shown below. The sample of width 5mm and length 20mm was cut out from the produced polymer film (retardation plate), and one end was fixed and it hanged in 25 degreeC and the atmosphere of 20% RH (R0). 0.5g of weight was hanged on the other end and left for 10 minutes to measure the length (L0). Next, length L1 was measured, leaving temperature at 25 degreeC and making humidity 80% RH (R1). The hygroscopic expansion coefficient was calculated by the following equation. The measurement carried out 10 samples with respect to the same sample, and adopted the average value.

Hygroscopic expansion coefficient [/% RH] = {(L1-L0) / L0} / (R1-R0)

It was found out that the dimensional change due to the moisture absorption should be small in the free volume in the polymer film. A large influence on the free volume is the amount of residual solvent in the production of the membrane, and the smaller the dimensional change is.

A general technique for reducing residual solvents is to dry at high temperatures and for a long time, but if it is too long, of course, the productivity decreases. Therefore, it is preferable that the residual solvent amount with respect to a cellulose acylate film exists in the range of 0.01-1 mass%, It is still more preferable that it exists in the range of 0.02-0.07 mass%, It is most preferable that it exists in the range of 0.03-0.05 mass%. Do.

By controlling the amount of the residual solvent, a polarizing plate having optical compensation ability can be manufactured at low cost and high productivity.

Residual solvent amount means the amount of volatile matter with respect to the mass of solid content, and is defined by the following formula.

Residual Solvent Amount (mass%) = ((W-W0) / W0) × 100

W ： Sample smoke mass

W0: sample mass after drying the sample smoke film at 110 ° C for 2 hours

The residual solvent amount was measured by dissolving a certain amount of samples in chloroform and using a gas chromatograph (GC18A, manufactured by Shimadzu Corporation).

In the solution casting method, a film is produced using a solution (dope) in which a polymer material is dissolved in an organic solvent. Drying in the solution casting method is largely separated into drying on the drum (or bend) surface and drying at the time of film transport, as will be described later. In the case of drying on the drum (or bend) surface, it is preferable to dry slowly at a temperature not exceeding the boiling point of the solvent used (if it exceeds the boiling point, bubbles are formed).

In order to realize the cellulose acylate film of the present invention, it is important to warm it immediately after peeling from the drum (or bend). 110 to 160 degreeC is preferable and 120 to 150 degreeC of heating temperature is more preferable.

In addition, it is preferable to perform drying at the time of film conveyance at the glass transition point of a polymer material +/- 30 degreeC, More preferably, +/- 20 degreeC.

Moreover, as another method of making the dimensional change by moisture absorption small, it is preferable to add the compound which has a hydrophobic group. The material having a hydrophobic group is not particularly limited as long as it is a material having a hydrophobic group such as an alkyl group or a phenyl group in the molecule, but a material corresponding to the plasticizer or anti-degradant added to the cellulose acylate film is particularly preferably used. Examples thereof include triphenyl phosphate (TPP) and tribenzylamine (TBA).

It is preferable that the addition amount of the compound which has these hydrophobic groups exists in the range of 0.01-10 mass% with respect to the solution (dope) to adjust, It is more preferable to exist in the range which is 0.1-5 mass%, and of 1-3 mass% Most preferably in the range.

[Surface Treatment of Transparent Support and Cellulose Acylate Film]

It is preferable to surface-treat a transparent support body, such as a cellulose acylate film. In particular, in the case of forming the alignment film between the optically anisotropic layer and the transparent support, the support is surface-treated to uniformly apply the composition for forming the alignment film and to sufficiently express the adhesion between the alignment film and the transparent support applied by coating, thereby making the surface hydrophilic. It is preferable to perform the hydrophilization surface treatment modified with.

As an aspect of hydrophilization treatment with respect to transparent support bodies, such as a cellulose acylate film, corona discharge treatment, a glow discharge treatment, a flame treatment, an ultraviolet irradiation treatment, and a frame plasma treatment are mentioned as a physical treatment. Examples of the wet treatment include ozone treatment, oxidation treatment, acid treatment, and alkali treatment. Specifically, Japanese Patent Application Laid-Open No. 2001-1745 (issued March 15, 2001), p. 30-31, Japanese Patent Application Laid-Open No. 2001-9973, and the like can be given.

Moreover, it is also preferable to form the undercoat layer (for example, described in Unexamined-Japanese-Patent No. 7-333433).

From the viewpoint of maintaining the planarity of the film, in these treatments, the temperature of the cellulose acylate film is preferably set to Tg (glass transition temperature) or lower, specifically 150 ° C or lower.

When using as a transparent protective film of a polarizing plate, it is especially preferable to perform acid treatment or alkali treatment, ie, saponification process with respect to a cellulose acylate, from an adhesive viewpoint with a polarizing film.

Hereinafter, especially preferable alkali saponification process is demonstrated.

The alkali saponification treatment of the cellulose acylate film is preferably carried out in a cycle in which the film surface is immersed in an alkaline solution, neutralized with an acidic solution, washed with water and dried.

It is preferable from the simplicity of a hydrophilicity treatment apparatus and the maintenance property (it is hard to corrode) of an hydrophilization treatment apparatus to give alkali saponification process by alkaline solution.

As the alkali saponification treatment, any method may be used, such as immersing the transparent support in the alkaline solution, spraying or applying the alkaline solution on the transparent support surface. More preferred is an alkali saponification treatment by a coating method that can uniformly saponify only one side of the transparent support without staining.

It is preferable to make the saponification process into the processing temperature of the range which does not exceed 120 degreeC in which the deformation | transformation of a film to be processed, deterioration of a processing liquid, etc. do not generate | occur | produce. Moreover, the range whose temperature is 10 degreeC or more and 100 degrees C or less is preferable. In particular, the temperature of 20-60 degreeC is preferable.

In addition, although the time of a saponification process is suitably adjusted and determined according to an alkaline solution and processing temperature, it is preferable to carry out in 1 second-60 second.

[Alkaline solution]

The alkaline solution of the present invention is preferably an alkaline solution of pH 11 or higher. More preferably, it is pH 12-14.

Examples of the alkali agent used in the alkaline solution include inorganic alkali agents such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and also 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 Organic alkalis, such as hydroxide and triethylbutylammonium hydroxide, are also used. These alkaline agents may be used alone or in combination of two or more thereof, and some may be added, for example, in the form of halogenated salts.

Among these alkalizing agents, sodium hydroxide or potassium hydroxide is preferable because pH adjustment in a wide pH range is possible by adjusting the amount thereof.

The concentration of the alkali agent in the alkaline solution is determined by the type of the alkali agent used, the reaction temperature and the reaction time, but the content of the alkali agent is preferably 0.1 to 3 mol / kg, more preferably 0.5 to 2 mol / kg in the alkali solution. .

The solvent of the alkaline solution is preferably a mixed solution of water and a water-soluble organic solvent. As the water-soluble organic solvent, any organic solvent that can be miscible with water can be used, but the boiling point is preferably 120 ° C. or lower from the viewpoint of the concentration suppression over time of the treatment liquid and the removal (dryability) from the film after the treatment. More preferably, it is 60-120 degreeC, More preferably, it is 100 degrees C or less.

Among them, preferred organic solvents preferably have inorganic / organic values (I / O values) of 0.5 or more and solubility parameters 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 18 to 31 [mJ / m 3] ^1/2 . If the I / O value is stronger in inorganicity than this range or the solubility parameter is lower, the alkali saponification rate is lowered and the overall uniformity of the saponification degree becomes unsatisfactory. On the other hand, if the I / O value is the organic side than the above range or the solubility parameter is the solubility side, the saponification rate is high, but haze is likely to occur, and therefore, it is similarly unsatisfactory in terms of overall uniformity.

In addition, the use of an organic solvent, in particular, the organic solvent in the organic and solubility ranges in combination with a surfactant and / or a compatibilizer described below maintains a high saponification rate and improves the degree of saponification over the entire surface. .

Examples of the water-soluble organic solvent having preferred property values include those described in the Japan Organic Synthetic Chemistry Association edition, "New Solvent Pocket Book" (Ohm Co., Ltd., published in 1994), and the like. The organic value (I / O value) is described, for example, in Yoshio Tanaka, "Organic Concept Map" (published in 1983, p.1-31).

Specifically, monovalent aliphatic alcohols (e.g., methanol, ethanol, propanol, butanol, pentanol, hexanol, etc.), alicyclic alkanols (e.g., cyclohexanol, methylcyclohexanol, methoxycyclohexanol, Cyclohexylmethanol, cyclohexylethanol, cyclohexyl propanol, etc.), phenylalkanols (e.g. benzyl alcohol, phenylethanol, phenylpropanol, phenoxyethanol, methoxybenzyl alcohol, benzyloxyethanol, etc.), heterocyclic alkanols (fur Furyl alcohol, tetrahydrofurfuryl alcohol, etc.) and monoethers of glycol compounds (methyl cellosolve, ethyl cellosolve, propyl cellosolve, methoxymethoxyethanol, butyl cellosolve, hexyl cellosolve, methyl Carbitol, ethyl carbitol, propyl carbitol, butyl carbitol, ethoxytriglycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, etc. Tones, methyl ethyl ketone, methyl isobutyl ketone, etc.), amides (e.g., N, N-dimethylformamide, dimethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, etc.) ), Sulfoxides (e.g. dimethyl sulfoxide) and ethers (e.g. tetrahydrofuran, pyran, dioxane, trioxane, dimethyl cellosolve, diethyl cellosolve, dipropyl cellosolve, methyl ethyl cell Rosolve, dimethyl carbitol, methyl ethyl carbitol, etc.) etc. are mentioned. You may use the organic solvent to be used individually or in mixture of 2 or more types.

It is preferable that at least 1 type of organic solvent in the case of mixing an organic solvent individually or 2 or more types is solubility with respect to water. The solubility of the organic solvent in water is preferably 50% by mass or more, more preferably freely mixed with water. As a result, an alkali agent, a salt of a fatty acid produced by saponification treatment, and a salt of carbonic acid generated by absorbing carbon dioxide in the air Alkali solution with sufficient solubility to etc. can be prepared.

The use ratio of the organic solvent in the solvent is determined according to the kind of solvent, miscibility with water (soluble), reaction temperature and reaction time.

As for the mixing ratio of water and an organic solvent, 3/97-85/15 mass ratio is preferable. 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 surface of the film is easily saponified evenly without compromising the optical properties of the acylate film.

As an organic solvent contained in the alkaline solution used in the present invention, as an organic solvent (e.g., fluorinated alcohol, etc.) which is different from the organic solvent having the above-mentioned preferred I / O value, as a surfactant and a dissolution aid for the compatibilizer described later. You may use together. It is preferable to make content into 0.1-5 mass% with respect to the gross mass of alkaline solution.

It is preferable that the alkaline solution used for this invention contains surfactant. By adding a surfactant, the surface tension is lowered to make the coating easier, or the uniformity of the coating film is increased to prevent elasticity breakdown. In addition, the presence of an organic solvent suppresses haze that is likely to occur and the saponification reaction proceeds uniformly. The effect becomes especially remarkable by coexistence of the compatibilizer mentioned later. There is no restriction | limiting in particular in surfactant used, Any of anionic surfactant, cationic surfactant, amphoteric surfactant, nonionic surfactant, and fluorine-type surfactant may be used.

Specifically, for example, Tokiyuki Yoshida, "The Surfactant Handbook (New Edition)" (engineering book, published in 1987), "Creation of Functionality, Material Development, and Application Technology of Surfactants" Part 1 (Technical Education Publications, 2000) The yearly publication) etc. are mentioned.

Among these surfactants, quaternary ammonium salts as cationic surfactants, various polyalkylene glycol derivatives as nonionic surfactants, polyethylene oxide derivatives such as various polyethylene oxide adducts, and betaine compounds as amphoteric surfactants are preferable. .

The use of a nonionic surfactant and an anionic surfactant or a nonionic surfactant and a cationic surfactant in an alkaline solution is preferably used because the effect of the present invention can be enhanced.

The addition amount with respect to the alkaline solution of these surfactant becomes like this. Preferably it is 0.001-10 mass%, More preferably, the range of 0.01-5 mass% is mentioned.

It is also preferable that the alkaline solution used in the present invention contains a compatibilizer. In this invention, a "compatibility agent" means the hydrophilic compound which becomes 50 g or more of water solubility with respect to 100 g of compatibilizers at the temperature of 25 degreeC. It is preferable that it is 80 g or more with respect to 100 g of compatibilizers, and, as for the solubility of the water of a compatibilizer, it is more preferable that it is 100 g or more. Moreover, when a compatibilizer is a liquid compound, it is preferable that boiling point is 100 degreeC or more, and it is more preferable that it is 120 degreeC or more.

The compatibilizer acts to prevent the drying of the alkaline solution attached to the wall surface of the bath or the like, which stores the alkaline solution, to suppress sticking, and to maintain the alkaline solution stably. In addition, after the alkali solution is applied to the surface of the transparent support and maintained for a predetermined time, the thin film of the applied alkaline solution is dried and the solid precipitates until the saponification process is stopped, and it is difficult for the solid to be washed out in the water washing process. It has the effect of preventing the making. In addition, phase separation of the organic solvent with water as a solvent is prevented. In particular, the coexistence of the surfactant with the organic solvent and the above-described compatibilizer makes the treated transparent support stable evenly even in the case of long haze and long continuous saponification treatment.

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

The polyol compound may be any of a low molecular weight compound, an oligomeric compound and a high molecular compound.

Examples of the aliphatic polyols include alkanediols having 2 to 8 carbon atoms (for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerin monomethyl ether, glycerin monomethyl ether, cyclohexanediol, and cyclohexane). Dimethanol, diethylene glycol, dipropylene glycol, etc.) and alkanes having 3 to 18 carbon atoms containing three or more hydroxyl groups (e.g., glycerin, trimethylolethane, trimethylolpropane, trimethylolbutane, hexane tri Ol, pentaerythritol, diglycerin, dipentaerythritol, inositol and the like).

As polyalkyleneoxy polyols, the alkylene diols mentioned above may be couple | bonded, and the other alkylene diol may couple | bond with each other, The polyalkylene polyol which couple | bonded the same alkylene diols is more preferable. In any case, it is preferable that it is 3-100, and, as for bond water, it is more preferable that it is 3-50. Specifically, polyethylene glycol, polypropylene glycol, poly (oxyethylene-oxypropylene) is mentioned, for example.

Examples of sugars include, for example, the Japanese Polymer Society of Polymer Experimental Editing Committee, "Natural Polymers," Chapter 2 (Kyoritsu Publishing Co., 1984), Oda Ryoi, et al. "Modern Industrial Chemistry 22, Natural Products Industrial Chemistry Ⅱ ( Water-soluble compounds described in Asakura Bookstore, 1967). Especially, the saccharide which does not show reducibility which does not have a free aldehyde group and a ketone group is preferable.

Sugars are generally classified into glucose, sucrose, trehalose type small sugars bonded with reducing groups, glycosides combined with reducing and non-saccharides of sugars, and sugar alcohols reduced by hydrogenation of sugars, all of which are suitably used in the present invention.

For example sucrose, trehalose, alkyl glycosides, phenol glycosides, mustard oil glycosides, D, L-arabits, ribits, xylites, D, L-solbits, D, L-mannites, D, L-its , D, L-tartrit, zrisheet, arozel sheet, and reduced water syrup. These sugars can be used individually or in combination of 2 or more types.

As a water-soluble polymer which has a repeating unit which has a hydroxyl group and / or an amide group, For example, natural gum (for example, gum arabic, guar gum, tragand gum, etc.), polyvinylpyrrolidone, dihydroxypropyl And an addition reactant of an acrylate polymer, cellulose or chitosan with an epoxy compound (ethylene oxide or propylene oxide).

Especially, polyol compounds, such as an alkylene polyol, polyalkyleneoxy polyol, and sugar alcohol, are preferable.

It is preferable that it is 0.5-25 mass% with respect to an alkali solution, and, as for content of a compatibilizer, it is more preferable that it is 1-20 mass%.

The alkaline solution used in the present invention may contain other additives. As another additive, well-known things, such as an antifoamer, an alkali solution stabilizer, a pH buffer, a preservative, and a fungicide, are mentioned, for example.

As described above, in the present invention, it is preferable that the transparent support is surface-treated with an alkaline solution containing an aqueous solution having a boiling point of 60 to 120 ° C and at least a surfactant and / or a compatibilizer (naturally containing an alkali agent). .

[Application saponification method of alkaline solution]

As a surface treatment method of the polymer film (Hereinafter, a "cellulose acylate film" is demonstrated in the description of this method as an example) using the said alkaline solution, the coating method which can process only one surface of a film is preferable. As a coating method, the dip coating method, the curtain coating method, the extrusion coating method, the bar coating method, and the E-type coating method are mentioned.

Furthermore, the process of saponifying a cellulose acylate film with an alkaline solution at the temperature whose surface is at least 10 degreeC or more, the process of maintaining the temperature of a cellulose acylate film at least 10 degreeC, and an alkaline solution are wash | cleaned with a cellulose acylate film, It is preferable to perform an alkali saponification process by a step of extruding.

When the surface of the cellulose acylate film is saponified with an alkaline solution at a predetermined temperature, a step of adjusting the predetermined temperature to a predetermined temperature before coating, a step of adjusting the alkali liquid to a predetermined temperature in advance, or a combination thereof Can be mentioned. It is preferable to combine with the process of adjusting to predetermined temperature before apply | coating.

After the saponification reaction, it is preferable to wash and remove the alkaline solution and the saponification reaction reactant from the film surface by water washing, neutralization and water washing or the like.

Specifically, the contents described in, for example, International Publication No. 02/46809 pamphlet or the like can be mentioned.

[Characteristics of Hydrophilized Transparent Support]

It is preferable that the hydrophilicity of the surface of the transparent support body which performed the said process is the following physical properties.

(1) It is preferable that the contact angle with water on the film surface exists in the range of 20-55 degree | times.

The contact angle with water is more preferably in the range of 25 to 50 degrees, and more preferably in the range of 30 to 45 degrees.

(2) It is preferable that the surface energy in the film surface exists in the range of 55-75 mN / m. It is more preferable to exist in the range of 60-75mN / m.

The evaluation method of surface energy (evaluation item (2)) can be calculated | required by the contact angle method, the wet heat method, and the adsorption method described in "The basics and application of a wet" (Realize, 1989). When using a cellulose acylate film as a transparent support body, it is preferable to use a contact angle method. Specifically, two solvents of which the surface energy is already known are dropped into the cellulose acylate film, and the contact angle of the side including the droplet is the angle between the tangent drawn on the droplet and the film surface at the intersection of the droplet surface and the film surface. It is defined as this, and the surface energy of a film can be calculated by calculation.

The transparent support having the specific surface shape and optical characteristics used in the third aspect of the present invention can be manufactured with reference to the above. In order to make the surface shape and optical characteristics within the above-mentioned range, (1) the above description As described in the (Adding and Mixing Method of Fine Particles), the monodisperse fine particles are a method for producing a film by a solution casting method, before being wet-dispersed prior to mixing and dispersing in dope to form a dispersion excluding coarse particles. As described above, the particle size of the fine particles is made constant so that particles having a particle size exceeding 500 μm do not exist. (2) As described above, the dope is subjected to microfiltration before the casting process, and (3) the above-mentioned. As described above, the metal support to be used in the casting step has irregularities on its surface to have a constant size, and (4) drying in the drying step of the dope as described above. To control the gun, (5) it is possible to refine the stretching condition of the drawing process as described above, properly adjusting the like. As a result, the variation of the slow axis angle is also suppressed. (6) As described above, the alignment film and the optically anisotropic layer are uniformly applied in the application surface by performing the hydrophilization treatment of the rapid saponification alkali solution treatment, thereby achieving an optical compensation sheet having good visibility.

An optical compensation sheet can form the optically anisotropic layer formed from the liquid crystal compound on the produced cellulose acylate film. It is preferable to form an alignment film between a cellulose acylate film and the optically anisotropic layer formed thereon. The alignment film functions to orient the liquid crystal compound used in the present invention in a constant direction. Therefore, the alignment film is essential for producing the optical compensation sheet of the present invention. However, if the alignment state is fixed after the alignment of the liquid crystal compound, the alignment film has played its role, and thus it is not necessarily essential as a component of the optical compensation sheet. That is, it is also possible to produce only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the cellulose acylate film to produce the optical compensation sheet.

[Alignment Film]

The alignment film has a function of defining the alignment direction of the liquid crystal compound. The alignment film is an organic compound (e.g., ω-) by rubbing treatment of an organic compound (preferably a polymer), evaporation of an inorganic compound, formation of a layer having microgrooves, or a Langmuir blowjet method (LB film). Trichoic acid, dioctadecylmethylammonium chloride, methyl stearate). Moreover, the oriented film in which an orientation function is produced by provision of an electric field, provision of a magnetic field, or light irradiation is also known. It is preferable to form an alignment film by the rubbing process of a polymer.

The alignment film provided in this invention is based on the kind of display mode of a liquid crystal cell.

In the display modes (eg, VA, OCB, HAN) in which most of the rod-like liquid crystalline molecules in the liquid crystal cell are substantially vertically aligned, the liquid crystal molecules of the optically anisotropic layer are oriented substantially horizontally. In a display mode (eg, STN) in which most of the rod-shaped liquid crystalline molecules in the liquid crystal cell are substantially horizontally oriented, the liquid crystal molecules of the optically anisotropic layer are oriented substantially vertically. In a display mode (eg, TN) in which most of the rod-like liquid crystalline molecules in the liquid crystal cell are substantially oriented at an angle, the liquid crystal molecules of the optically anisotropic layer are oriented substantially obliquely.

It is preferable to form an alignment film by the rubbing process of a polymer. Polyvinyl alcohol is a preferred polymer. Particularly preferred is a modified polyvinyl alcohol having a hydrophobic group bonded thereto.

Although the alignment film may be formed of one kind of polymer, it is more preferable to form by rubbing the layer made of two kinds of crosslinked polymers. As at least one kind of polymer, it is preferable to use one of a polymer which can be crosslinked by itself and a polymer which is crosslinked by a crosslinking agent.

The alignment layer is formed by reacting a polymer or a polymer having a functional group with a functional group between the polymers by light, heat, PH change, or the like; or a linking group derived from a crosslinking agent between polymers using a crosslinking agent which is a compound having high reaction activity. Can be formed by crosslinking between polymers.

Such crosslinking is performed by applying an alignment film coating liquid containing the polymer or a mixture of the polymer and the crosslinking agent onto the cellulose acylate film and then heating. Since durability can be ensured in a final product (optical compensation sheet), you may perform the process which crosslinks in any step from after apply | coating an oriented film on a cellulose acylate film to obtaining an optical compensation sheet.

Considering the orientation of the layer (optical anisotropic layer) made of the liquid crystal compound formed on the alignment film, it is also preferable to crosslink sufficiently after the alignment of the liquid crystal compound.

Crosslinking of an oriented film is generally performed by apply | coating an oriented film coating liquid on a cellulose acylate film, and heat-drying. It is preferable to sufficiently crosslink the alignment film in the heat treatment step at the time of forming the optical anisotropic layer described later by setting the heating temperature of the coating liquid low.

As a polymer used for an oriented film, the polymer which can be crosslinked by itself, or the polymer crosslinked by a crosslinking agent can be used. Of course, there are polymers available for both. Examples of the polymer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol acrylamide), styrene / vinyltoluene air Coalesce, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, carboxymethylcellulose, polyethylene, polypropylene, and polycarbonate Can be mentioned. Instead of a polymer, a silane coupling agent can be used.

Preferred polymers are water soluble polymers (eg poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol). Gelatin, polyvinyl alcohol and modified polyvinyl alcohol are preferred, and polyvinyl alcohol and modified polyvinyl alcohol are more preferred.

Moreover, it is most preferable to use together two types of polyvinyl alcohol or modified polyvinyl alcohol from which a polymerization degree differs.

It is preferable that polyvinyl alcohol exists in the range of 70-100% of saponification degree. The degree of saponification is more preferably in the range of 80 to 100%, still more preferably in the range of 85 to 95%. Moreover, it is preferable that the polymerization degree of polyvinyl alcohol exists in the range of 100-3000.

Examples of the modified polyvinyl alcohol include polyvinyl alcohol, such as copolymerization modification, modification by chain transfer, or modification by block polymerization. Examples of the modification group in the case of copolymerization modification include COONa, Si (OX) ₃ , N (CH ₃ ) ₃ Cl, C ₉ H ₁₉ COO, SO ₃ Na, and C ₁₂ H ₂₅ . Examples of the modification group in the case of modification by chain transfer include COONa, SH, and C ₁₂ H ₂₅ . In addition, examples of the modifying group in the case of modification by block polymerization include COOH, CONH ₂ , COOR, and C ₆ H ₅ .

Unmodified or modified polyvinyl alcohols having a saponification degree in the range of 80 to 100% are preferred. More preferred are unmodified polyvinyl alcohol and modified polyvinyl alcohol having a saponification degree in the range of 85 to 95%.

As modified polyvinyl alcohol, it is particularly preferable to use a modified product of polyvinyl alcohol with a compound represented by the following general formula. This modified polyvinyl alcohol is hereinafter referred to as specific modified polyvinyl alcohol.

Wherein R ¹ represents an alkyl group, acryloylalkyl group, methacryloylalkyl group or epoxyalkyl group; W represents a halogen atom, an alkyl group or an alkoxy group; X represents an active ester, an acid anhydride, or an acid halide Represents a required atomic group; p represents 0 or 1; and n represents an integer of 0 to 4;

It is preferable that the said specific modified polyvinyl alcohol is a modified substance of polyvinyl alcohol by the compound further represented with the following general formula.

In the formula, X ¹ represents an atomic group necessary for forming an active ester, an acid anhydride or an acid halide, and m represents an integer of 2 to 24.

Examples of the polyvinyl alcohol used to react with the compounds represented by these general formulas include the above-mentioned unmodified polyvinyl alcohol and those modified by copolymerization, that is, modified by chain transfer or modified by block polymerization. Modified products of polyvinyl alcohol, such as these, are mentioned. Preferable examples of the specific modified polyvinyl alcohol are described in Japanese Patent Laid-Open No. 9-152509.

Japanese Unexamined Patent Publication No. Hei 8-338913 discloses a method for synthesizing these polymers, measuring the visible absorption spectrum, and determining the rate of introduction of the modifying group.

Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds which act by activating a carboxyl group, active vinyl compounds, active halogen compounds, isoxazoles and dialdehyde starch. Examples of aldehydes include formaldehyde, glyoxal and glutalaldehyde. Examples of the N-methylol compound include dimethylol urea and methylol dimethyl hydantoin. As an example of a dioxane derivative, 2, 3- dihydroxy dioxane is mentioned. Examples of the compound which acts by activating a carboxyl group include carbenium, 2-naphthalenesulfonate, 1,1-bispyrrolidino-1-chloropyridinium and 1-morpholinocarbonyl-3- (sulfonataminomethyl ). Examples of active vinyl compounds include 1,3,5-triacroyl-hexahydro-s-triazine, bis (vinylsulfon) methane and N, N'-methylenebis- [β- (vinylsulfonyl) propionamide ] Can be mentioned. In addition, examples of the active halogen compound include 2,4-dichloro-6-hydroxy-S-triazine. These can be used in combination.

These are preferable when used in combination with the above water-soluble polymers, in particular polyvinyl alcohol and modified polyvinyl alcohols (including the above-mentioned specific modified substances). In consideration of productivity, the use of aldehydes having high reaction activity, particularly glutaraldehyde, is preferable.

Moisture resistance tends to improve the addition of many crosslinking agents. However, when 50 mass% or more of crosslinking agents are added with respect to a polymer, the orientation ability as an oriented film falls. Therefore, it is preferable that the addition amount of the crosslinking agent with respect to a polymer exists in the range of 0.1-20 mass%, and it is more preferable to exist in the range which is 0.5-15 mass%. Although the orientation film contains the crosslinking agent which did not react even after completion | finish of a crosslinking reaction, it is preferable that the quantity of the crosslinking agent is 1.0 mass% or less in an alignment film, and it is more preferable that it is 0.5 mass% or less. If the unreacted crosslinking agent is contained in the amount exceeding 1.0 mass% in an oriented film, sufficient durability will not be obtained. That is, when used in a liquid crystal display device, reticulation may occur when it is used for a long time or left for a long time in a high temperature, high humidity atmosphere.

Examples of the modified group of the modified polyvinyl alcohol 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, hydrocarbon groups having fluorine atom substitution, Thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like. As a specific example of these modified polyvinyl alcohol compounds, For example, Unexamined-Japanese-Patent No. 2000-56310 Paragraph No., US 2000-155216 Paragraph No. [0022]-[0145], 2002-62426 Paragraph No. The thing described in [0022]-[0022], etc. are mentioned.

Moreover, when orientation is performed by light irradiation, it has a photo-alignment group which expresses a photo-alignment function in a molecule | numerator. As these photo-orientation groups, it is a photo-alignment function by the photodimerization reaction which has described in liquid crystal, volume 3 (1) pages 3-16 (1999), Hasegawa Masaki, C = C bond, for example. Photo-orienting groups (e.g., polyene group, stilbene group, stilazole group, stilbazolium group, cinnamoyl group, hemithioindi meat, chalcone group, etc.) expressing Photo-alignment group (for example, group which has structures, such as a benzophenone group and a coumarin group) which expresses a photo-alignment function, is mentioned. Specifically, Paragraph No. of Unexamined-Japanese-Patent No. 2000-122069, 2002-317013, etc. are mentioned, for example.

[Carboxylic acid compounds contained in the alignment film]

It is preferable that the composition for orientation film formation of this invention contains a specific carboxylic acid compound.

Thereby, the shape of the coated surface of the optical compensation sheet obtained by applying the optically anisotropic layer after the alignment of the obtained alignment film by the alignment means is good and exhibits an improvement effect of reducing or eliminating optical defects such as white lines. One reason for this is that when the specific carboxylic acid compound contained in the alignment film is coated with an optically anisotropic layer with stable film surface hydrogen ion concentration of the alignment film and the like, one factor is considered to be a factor. do. In addition, when hydrophilicizing the surface of a transparent support body by alkali saponification process, even if there exists a some process liquid which remains on the film surface, it is thought that the alignment film of stable and favorable optical performance is formed. Naturally, since an effect changes with addition amount, it is necessary to adjust a suitable amount.

As a specific carboxylic acid compound, the carboxylic acid containing at least 1 sort (s) of the hydrogen atom containing polar group which has hydrogen bondability is mentioned. These carboxylic acids may be both aliphatic, aromatic, or heterocyclic compounds.

Specific polar groups include -OH, -SH, -NHR, -CONHR, -SO ₂ NHR, -HNCONHR, -NHSO ₂ NHR, -NHCOR ¹ and -NHSO ₂ R ¹ . With the proviso that 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 of 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 has 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, 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, henecosanyl group, docosanyl group, etc. ), A linear or branched alkenyl group having 2 to 22 carbon atoms (for example, a vinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, octenyl group, dodecenyl group, tridecenyl group, tetradecenyl Groups, hexadecenyl groups, octadecenyl groups, eicosenyl groups, docosenyl groups, butadienyl groups, pentadienyl groups, hexadienyl groups, octadienyl groups, etc.), linear or branched alkynyl groups having 2 to 22 carbon atoms (E.g., ethynyl group, propynyl group, butynyl group, hexynyl group, octanyl group, Decanyl group, dodecanyl group, etc.), alicyclic hydrocarbon group having 5 to 22 carbon atoms (e.g., cyclopentane, cyclopentene, cyclopentadiene, cyclohexane, cyclohexene, cyclohexadiene, cycloheptane, cycloheptene, cyclo Heptadiene, cyclooctane, cyclooctene, cyclooctadiene, decalin and the like).

As an aliphatic group, a C1-C18 linear and branched aliphatic group of 3-18 carbon atoms is more preferable.

As an aryl group, a C6-C18 aryl group (as an aryl ring, benzene, naphthalene, dihydronaphthalene, biphenylene etc.) is represented.

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 (as a heterocyclic group, for example, furanyl group, tetrahydrofuranyl group, pyranyl group) , Pyloyl group, pyridinyl group, pyridinyl group, morpholinyl group, thienyl group, benzothienyl group and the like).

The aliphatic group, the aryl group and the heterocyclic group may each have a substituent, and as the substituent which can be introduced therein, a monovalent nonmetallic atom group except hydrogen is used.

Specific examples of the nonmetallic atom group include 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 groups, aryl groups, and heterocyclic groups have the same meanings as those of 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 in R ¹¹ has the same meaning as the aliphatic group represented by R. As an aryl group in R <^11> , the same thing as the aryl group represented by said R is mentioned. Examples of the heterocyclic group in R ¹¹ include the same heterocyclic group represented by R described above. Such an aryl group may further have a substituent and the same thing as what was illustrated as a substituent which can introduce | transduce into the aliphatic group, aryl group, and heterocyclic group represented by said R is mentioned.

R ¹² represents the same as a hydrogen atom or a R ¹¹ group.

R ¹³ and R ¹⁴ each independently represent the same hydrogen atom or R ^11, and R ¹³ and R ¹⁴ may be bonded to each other to form a 5-membered or 6-membered ring containing an N atom.

R ¹⁵ and R ¹⁶ each independently represent an aliphatic group having 1 to 22 carbon atoms, an aryl group having 6 to 14 carbon atoms, or -OR ¹¹ . The aliphatic group in R ¹⁵ and R ¹⁶ has the same meaning as the aliphatic group represented by R. As an aryl group in R <^15> and R <^16> , the same thing as the aryl group shown by said R is mentioned. Such an aryl group may further have a substituent and the same thing as what was illustrated as a substituent which can introduce | transduce into the aliphatic group, aryl group, and heterocyclic group represented by said R is mentioned.

R ¹⁷ , R ¹⁸ and R ¹⁹ each independently represent a hydrocarbon group having 1 to 22 carbon atoms or -OR ²⁰ , but at least one of these substituents represents a hydrocarbon group. The hydrocarbon group represents the same as the aliphatic group and the aryl group represented by the above R, and -OR ²⁰ represents the same content as the above -OR ¹¹ .

The aliphatic group, aryl group, and heterocyclic group in R <^1> represent the same thing as R.

Specific carboxylic acid compounds of the present invention include aliphatic carboxylic acids having 1 to 22 carbon atoms (excluding carbon atoms of the carboxylic acid), aromatic carboxylic acids having 6 to 14 carbon atoms, and carboxylic acids of heterocyclic carboxylic acids. It is a compound, and it is especially preferable that pKa is 6.5 or less. More preferably, it is a compound whose pKa of carboxylic acid is 3.0-6.5.

Specific examples of these specific carboxylic acid compounds include oxyacids (for example, glycolic acid, lactic acid, glycerin acid, α-oxyalkanoic acid (alkanes such as alkanes having 3 to 18 carbon atoms)), amino acids, α-oxy-β-amino acids, α-oxy-γ-amino acids, β-oxy-α-amino acids, compounds in which the hydroxyl groups of these oxyacids or oxyamino acids are derived from alkoxy groups, hydroxycyclohexanecarboxylic acids, and hydroxides Cyclic anhydrides (succinic acid, maleic acid) at least one hydroxyl group of oxybenzenecarboxylic acids, polyols (e.g., alkanediol, glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, cyclohexanediol, etc.) , Esterified with glutaric acid, adipic acid, anhydrides such as cyclohexanedicarboxylic acid, phthalic acid, and the like, polyamino compounds (e.g., alkylenediamine, diethylenetriamine, triethylenetetramine, cyclic Rohexane diamine, phenylenediamine etc.) and the compound derived from the compound amidated by cyclic carboxylic anhydride are mentioned, The compound of this invention is not limited to these.

More preferably, the carboxylic acid compound which is polycarboxylic acid containing at least 1 hydroxyl group, and the at least 1 carboxyl group is esterified is mentioned.

Examples of the polycarboxylic acid containing at least one hydroxyl group include tartaric acid, malic acid, tartaric acid, citric acid, oxyglutamic acid (β-form, γ-form), and at least two hydroxyl groups of the polyol. The compound esterified by acid anhydride, etc. are mentioned.

It is preferable that at least one carboxylic acid of these polycarboxylic acid compounds is ester-substituted by a C1-C22 hydrocarbon group.

The specific aspect of the C1-C18 hydrocarbon group substituted by ester is the same meaning as the aliphatic group, aromatic group, and heterocyclic group described by said R. In addition, these hydrocarbon groups may be substituted, and the thing of the same content is mentioned if it is substituted by said R as a substituent.

It is preferable to add the specific carboxylic acid compound of this invention in the ratio of 0.01-1.0 mass% in the composition for oriented film formation. Moreover, 0.02-0.5 mass% is preferable.

In this range, an optically defect-free optical compensation sheet such as a white string in which the strength of the film is sufficiently maintained is obtained. In addition, even if the long film is produced continuously can be produced with a very stable performance.

An oriented film is a cured film which can be formed by apply | coating the coating liquid containing the said polymer, crosslinking agent, and specific carboxylic acid which are the composition for oriented film formation on a transparent supporter, and then heat-drying (crosslinking) and orientating it. . What is necessary is just to perform a crosslinking reaction at arbitrary times after apply | coating on a transparent support body. In the case of using a water-soluble polymer such as polyvinyl alcohol as the composition for forming an alignment film, it is preferable that the coating liquid is a mixed solvent of an organic solvent (for example, methanol) and water having a bubble removing effect. As for the ratio, 0: 100-99: 1 are preferable for water: methanol by mass ratio, and it is more preferable that it is 0: 100-91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the layer surface defect of an oriented film and an optically anisotropic layer is remarkably reduced.

The coating method of the alignment film is preferably a spin coating method, a dip coating method, a curtain coating method, an extrusion coating method, a rod coating method or a roll coating method. In particular, the rod coating method is preferable. In addition, the film thickness after drying is preferably 0.1 to 10 mu m. Heat drying can be performed at 20 degreeC-110 degreeC. In order to form sufficient crosslinking, 60 to 100 degreeC is preferable, and 80 to 100 degreeC is especially preferable. Although drying time can be made into 1 minute-36 hours, Preferably they are 1 minute-30 minutes. More preferably, they are 5 minutes-30 minutes.

Further, when the coating liquid containing the composition for forming an alignment film of the present invention is applied to a support and dried to be oriented by the alignment means, and then the coating liquid for the optically anisotropic layer is applied, the surface of the alignment film is maintained in the range of pH 2.0 to 6.9. This is preferred. Moreover, pH 2.5-5.0 are more preferable. When glutalaldehyde is used, pH 4.5-5.5 is preferable and pH 5 is especially preferable.

Moreover, when apply | coating this coating liquid for optically anisotropic layers, it is preferable to implement in the range whose pH fluctuation range ((DELTA) pH) of the surface of the oriented film in the width direction to apply | coat is ± 0.30. More preferably, ΔpH is in a range of ± 0.15.

The optical compensation sheet which apply | coated the optically anisotropic layer in this range is preferable because the optical defect is remarkably reduced.

In the method for measuring the pH value of the alignment film surface, the sample coated with the alignment film is allowed to stand for one day in an environment of (temperature 25 ° C / humidity 65% RH), and then 10 ml of pure water is supplied in a nitrogen atmosphere to quickly adjust the pH to the pH instrument. Read the value.

The pH value of the surface of the alignment film of the present invention is specified, and the control of ΔpH in the coating width direction is performed by the coating by the rod coating method. In addition, it is also effective to control the air flow rate, the wind direction, and the like when using the drying temperature of the membrane surface and the drying wind.

The alignment film can be obtained by crosslinking the polymer layer as described above and then rubbing the surface.

The said rubbing process can apply the processing method employ | adopted widely as a liquid-crystal aligning process of LCD. That is, the method of obtaining an orientation by rubbing the surface of an oriented film in a fixed direction using paper, a gauze, a felt, rubber or nylon, polyester fiber, etc. can be used. Generally, it carries out by rubbing a few times using the cloth etc. which the hair | bristle hair of average length was made, the fiber uniform in length and thickness.

In the case of photoalignment by light irradiation, a light source serving as a light irradiation apparatus may be a high-pressure mercury lamp, a xenon lamp, a fluorescent lamp, a laser, or the like. In order to photoalign the light dimerization compound, the light source and the polarizer are combined (polarizer). Ultraviolet light is irradiated on the photoalignment film with linearly polarized light. As a polarizer, stretch dye PVA is mainly used. As this linearly polarized ultraviolet irradiation device, what is disclosed by Unexamined-Japanese-Patent No. 10-90684 can be used, for example.

0.01-10 micrometers is preferable, as for the thickness of an oriented film, 0.01-5 micrometers is more preferable, 0.05-1 micrometer is still more preferable.

[Optical anisotropic layer]

The optically anisotropic layer formed from the liquid crystal compound can be formed on the alignment film formed on the cellulose acylate film.

The liquid crystalline compound used for the optically anisotropic layer contains a rod-like liquid crystalline compound and a discotic liquid crystalline compound. The rod-like liquid crystalline compound and the discotic liquid crystalline compound may be polymer liquid crystals or low molecular liquid crystals, and those in which the low molecular liquid crystals are crosslinked and do not exhibit liquid crystallinity.

An optically anisotropic layer can be formed by apply | coating the liquid crystal compound and the coating liquid containing a polymeric initiator and arbitrary components on an orientation film as needed.

As a solvent used for adjustment of a coating liquid, an organic solvent is used preferably. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides ( Chloroform, dichloromethane, tetrachloroethane), esters (e.g. methyl acetate, butyl acetate), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, 1,2-dimethoxyethane) It contains. Alkyl halides and ketones are preferred. You may use together 2 or more types of organic solvents.

Application | coating of a coating liquid can be performed by a well-known method (for example, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

As a rod-shaped liquid crystalline compound, azomethines, azoxy compounds, cyano biphenyls, cyano phenyl esters, benzoic acid esters, cyclohexane carboxylic acid phenyl esters, cyano phenyl cyclohexane, and cyano substituted phenyl pyrides Midines, alkoxy substituted phenylpyrimidines, phenyldioxanes, tolans and alkenylcyclohexylbenzonitriles are preferably used.

The rod-like liquid crystalline compound also contains a metal complex. Moreover, the liquid crystal polymer which contains a rod-shaped liquid crystalline compound in a repeating unit can also be used as a rod-shaped liquid crystalline compound. In other words, the rod-like liquid crystalline compound may be combined with a polymer.

Regarding the rod-shaped liquid crystalline compound, Japanese Journal of Chemistry, Volume 22, Chemistry of Liquid Crystals (1994) Japanese Chemical Society, edited Chapters 4, 7 and 11 and the Liquid Crystal Devices Handbook Japanese Society for the Promotion of Japan 142 Committee Edit 3 It is described in the chapter.

It is preferable that the birefringence of the rod-like liquid crystal compound is in the range of 0.001 to 0.7.

It is preferable that a rod-shaped liquid crystalline compound has a polymeric group in order to fix the orientation state. Examples of the polymerizable group (Q) are shown below.

The polymerizable group (Q) is preferably an unsaturated polymerizable group (Q1 to Q7), an epoxy group (Q8) or an aziridinyl group (Q9), more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group (Q1 to Q6). Is most preferred.

The rod-like liquid crystalline compound preferably has a molecular structure that is substantially symmetrical with respect to the short axis direction. For this purpose, it is preferable to have a polymeric group at both ends of a rod-shaped molecular structure.

The example of a rod-shaped liquid crystalline compound is shown below.

The optically anisotropic layer contains a rod-like liquid crystalline compound or a polymerizable initiator or optional additive (for example, a plasticizer, a monomer, a surfactant, a cellulose ester, a 1,3,5-triazine compound, a chiral agent) to be described later. It can form by apply | coating a liquid crystal composition (coating liquid) on an oriented film.

Examples of discotic liquid crystal compounds include C. Destrade et al., Mol. Cryst. Benzene derivatives described in Vol. 71, p. 111 (1981), C. Destrade et al., Mol. Cryst. A report of the Truxen derivatives described in Volume 122, page 141 (1985), Physics lett, A, 78, page 82 (1990), B. Kohne et al., Angew. Chem. 96, page 70 (1984), cyclohexane derivatives and J. M. Lehn et al., J. Chem. Commun., Page 1794 (1985), by J. Zhang et al., J. Am. Chem. Soc. Azacrown and phenylacetylene macrocycles described in volume 116, page 2655 (1994). Moreover, as a discotic liquid crystalline compound, these are also the structure which made these into the mother nucleus of a molecular center generally, and the linear alkyl group, the alkoxy group, the substituted benzoyloxy group, etc. were linearly substituted by the linear chain, and show liquid crystallinity. In addition, in the present invention, the optically anisotropic layer formed from the discotic liquid crystalline compound does not have to be the final compound as the final material. For example, the low molecular discotic liquid crystalline compound has a group reacting with heat or light. It includes polymerized or crosslinked by reaction with heat, light and the like and high molecular weight to lose liquid crystallinity. Preferable examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about the superposition | polymerization of a discotic liquid crystalline compound, it is described in Unexamined-Japanese-Patent No. 8-27284.

In order to fix a discotic liquid crystalline compound by superposition | polymerization, it is necessary to couple a polymeric group as a substituent to the disc core of a discotic liquid crystalline compound. However, if the polymerizable group is directly linked to the disc-shaped core, it becomes difficult to maintain the alignment state in the polymerization reaction. Thus, a linking group is introduced between the disk core and the polymerizable group. Therefore, it is preferable that the disk type liquid crystalline compound which has a polymeric group is a compound represented by following formula (III).

(III) D (-L-Q) n

In the formula, D is a disc-shaped core; L is a divalent linking group, Q is a polymerizable group, and n is an integer of 4 to 12.

An example of disk-shaped core D is shown below. In each of the examples below, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

In formula (III), the divalent linking group (L) is a divalent selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, -CO-, -NH-, -O-, -S- and combinations thereof. It is preferable that it is a linking group. The divalent linking group (L) is more preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO-, -NH-, -O-, and -S- are combined. . The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and -0- are combined. It is preferable that carbon number of an alkylene group is 1-12. It is preferable that the carbon atom number of an alkenylene group is 2-12. The arylene group preferably has 6 to 10 carbon atoms.

Examples of the divalent linking group L are shown below. The left side binds to the disk-shaped core (D), and the right side binds to the polymerizable group (Q). AL means an alkylene group or an alkenylene group, AR means an arylene group. Moreover, the alkylene group, alkenylene group, and arylene group may have a substituent (for example, an alkyl group).

L1 ： -AL-CO-O-AL-

L2 ： -AL-CO-O-AL-O-

L3 ： -AL-CO-O-AL-O-AL-

L4 ： -AL-CO-O-AL-O-CO-

L5 ： -CO-AR-O-AL-

L6 ： -CO-AR-O-AL-O-

L7 ： -CO-AR-O-AL-O-CO-

L8 ： -CO-NH-AL-

L9 ： -NH-AL-O-

L10 ： -NH-AL-O-CO-

L11 ： -O-AL-

L12 ： -O-AL-O-

L13 ： -O-AL-O-CO-

L14 ： -O-AL-O-CO-NH-AL-

L15 ： -O-AL-S-AL-

L16 ： -O-CO-AR-O-AL-CO-

L17 ： -O-CO-AR-O-AL-O-CO-

L18 ： -O-CO-AR-O-AL-O-AL-O-CO-

L19 ： -O-CO-AR-O-AL-O-AL-O-AL-O-CO-

L20 ： -S-AL-

L21 ： -S-AL-O-

L22 ： -S-AL-O-CO-

L23 ： -S-AL-S-AL-

L24 ： -S-AR-AL-

The polymerizable group (Q) of Formula (III) is the same as that of the polymerizable group (Q) demonstrated by the rod-shaped liquid crystalline compound.

In formula (III), n is an integer of 4-12. The specific number is determined according to the type of disk-shaped core (D). Moreover, although the combination of some L and Q may differ, the same thing is preferable.

In the case of using a discotic liquid crystalline compound, the optically anisotropic layer is a layer having negative birefringence, and the surface of the discotic structural unit is inclined with respect to the surface of the cellulose acylate film, and the surface of the discotic structural unit and the surface of the cellulose acylate film It is preferable that this angle is made to change in the depth direction of an optically anisotropic layer.

The angle (inclined angle) of the surface of the disk-shaped structural unit is generally the depth direction of the optically anisotropic layer, and increases or decreases with the increase of the distance from the bottom surface of the optically anisotropic layer. It is preferable that the inclination angle increases with increasing distance. The change in the inclination angle includes a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, and an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the thickness direction. The inclination angle preferably increases or decreases as a whole even if it includes a region in which the inclination angle does not change. And it is preferable that the inclination angle is increasing as a whole, and it is especially preferable to change continuously.

The inclination angle of the disk-shaped unit on the support side can generally be adjusted by selecting the material of the disk-shaped liquid crystalline compound or alignment film or by selecting the rubbing treatment method. In addition, the inclination angle of the disk-shaped unit on the surface side (air side) can generally be adjusted by selecting another compound to be used with the disk-shaped liquid crystal compound or the disk-shaped liquid crystal compound. Examples of the compound used together with the discotic liquid crystalline compound include plasticizers, surfactants, polymerizable monomers and polymers. The degree of change of the inclination angle can also be adjusted by the same selection as described above.

As the plasticizer, surfactant, and polymerizable monomer used together with the discotic liquid crystalline compound, any compound may be used as long as it has compatibility with the discotic liquid crystalline compound and does not change the inclination angle of the discotic liquid crystalline compound or inhibits the orientation. have. Among these, a polymerizable monomer (for example, a compound having a vinyl group, a vinyloxy group, an acryloyl group and a methacryloyl group) is preferable.

For example, Paragraph No. 0018 of Unexamined-Japanese-Patent No. 2002-296423-what is described in [0020] is mentioned. The amount of the compound added is generally in the range of 1 to 50% by mass, and preferably 5 to 30% by mass, based on the discotic liquid crystalline compound.

As surfactant used together with a discotic liquid crystalline compound, a conventionally well-known compound is mentioned, Especially a fluorine-type compound is preferable. Specifically, the compound of Paragraph No. 0028-0056 of Unexamined-Japanese-Patent No. 2001-330725 is mentioned.

As a polymer used with a discotic liquid crystalline compound, any polymer can be used as long as it has compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound. Examples of the polymer include cellulose esters. Preferred examples of cellulose esters include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose and cellulose acetate butyrate. The addition amount of the polymer is generally in the range of 0.1 to 10% by mass, more preferably in the range of 0.1 to 8% by mass, more preferably 0.1 to 5, in order not to inhibit the orientation of the discotic liquid crystalline compound. It is more preferable to exist in the range of mass%.

The optically anisotropic layer is generally applied by applying a solution containing a discotic liquid crystalline compound and another compound in a solvent onto an alignment film, followed by drying, followed by heating to a discotic nematic phase formation temperature, and then maintaining an orientation state (discotic nematic phase). It is obtained by cooling. Alternatively, the optically anisotropic layer is applied by applying a solution containing a discotic liquid crystalline compound and other compounds (eg, a polymerizable monomer, a photopolymerization initiator) to a solvent on an alignment layer, followed by drying to a discotic nematic phase formation temperature. It is obtained by polymerizing and further cooling (by irradiation of UV light or the like). The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

[Fixing the Orientation State of Liquid Crystal Compound]

The aligned liquid crystal compound can be fixed while maintaining the alignment state. It is preferable to perform fixation by a polymerization reaction. Polymerization includes thermal polymerization using a thermal initiator and photopolymerization using a photopolymerization initiator. Photopolymerization is preferred.

Examples of photopolymerization initiators include α-carbonyl compounds (described in the specifications of US Pat. No. 23,684,1, 2367670), acyloinether (described in the specification of US Pat. No. 2448828), compounds of α-hydrocarbon substituted aromatic acyl (US Patent No. 2722512), Multinuclear Quinone Compounds (described in each of US Pat. No. 3046127, No. 2951758), and combinations of triarylimidazole dimers with p-aminophenylketone (described in US Pat. No. 3549367) ), Acridine and phenazine compounds (Japanese Patent Laid-Open No. 60-105667, described in US Pat. No. 4239850) and Oxadiazole compounds (described in US Pat. No. 4212970).

It is preferable to exist in the range of 0.01-20 mass% of solid content of a coating liquid, and, as for the usage-amount of a photoinitiator, it is more preferable to exist in the range of 0.5-5 mass%.

It is preferable to use ultraviolet-ray for the light irradiation for superposition | polymerization of a liquid crystalline compound.

The irradiation energy is preferably in the range of 20 mJ / cm 2 to 50 J / cm 2, more preferably in the range of 20 to 5000 mJ / cm 2, and most preferably in the range of 100 to 800 mJ / cm 2. Further, in order to promote the photopolymerization reaction, light irradiation may be performed under heating conditions. You may form a protective layer on an optically anisotropic layer.

It is preferable that the thickness of an optically anisotropic layer is 0.1-10 micrometers, It is more preferable that it is 0.5-5 micrometers, It is most preferable that it is 0.7-3 micrometers. However, depending on the liquid crystal cell mode, in order to obtain high optical anisotropy, an optically anisotropic layer may be thickened (3-10 micrometers).

The orientation state of the liquid crystalline molecules in the optically anisotropic layer is determined according to the type of display mode of the liquid crystal cell as described above. The orientation state of liquid crystalline molecules is specifically controlled by the kind of liquid crystalline molecule, the kind of alignment film, and the use of the additive (for example, a plasticizer, a polymer, surfactant) in an optically anisotropic layer.

As described above, the optical compensation sheet of the present invention is produced.

The optical compensation sheet of this invention exhibits the function remarkably by attaching to a polarizing plate or using it as a protective film of a polarizing plate.

Next, the polarizing plate of this invention and its manufacture are demonstrated in detail.

<Polarizing plate>

The polarizing plate of this invention is a polarizing plate which consists of a polarizing film and two transparent protective films arrange | positioned at both sides, It is characterized by using the optical compensation sheet of this invention for one side of this transparent protective film. Here, "one side" necessarily means that one side uses the optical compensation sheet of the present invention, and both sides may be constituted by the optical compensation sheet of the present invention.

[Transparent protective film of polarizing plate]

In the present invention, the transparent protective film, ie, the protective film, means that the light transmittance is 80% or more. As a transparent protective film other than the said optical compensation sheet of this invention, a cellulose ester film, Preferably an acetyl cellulose film is used. It is preferable to form a cellulose ester film by the solvent casting method as described in the description column of the said transparent support body. It is preferable that it is 20-200 micrometers, and, as for the thickness of a transparent protective film, it is more preferable that it is 30-100 micrometers. Especially preferably, it is 30-80 micrometers.

By using the optical compensation sheet of the present invention on one side of the polarizing plate as in the present invention, the stress (strain × cross-sectional area × elastic modulus) accompanying the dimensional change of the polarizing film is small without using a transparent protective film between the polarizing film and the optically anisotropic layer. A thin polarizing plate is created. When the polarizing plate according to the present invention is mounted on a large liquid crystal display device, an image with high display quality is displayed without causing problems such as light leakage.

[Surface Treatment of Optical Compensation Sheet]

In order to improve the adhesiveness of an optical compensation sheet and a polarizing plate, it is preferable to surface-treat the surface on the polarizing film side of an optical compensation sheet. As the surface treatment, corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, ozone treatment, acid treatment or alkali treatment are 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, for example, the above air number 2001-1745 p.30-31. Can be. It is preferable to carry out alkali treatment of this invention, and the thing similar to a base material can be mentioned by the alkali solution saponification process in the coating method of this invention.

[Polarizing Film]

The polarizing film used for this invention is Optiva Inc. normally. The polarizing film which consists of a coating type polarizing film or a binder represented by an iodine, or a dichroic dye is preferable.

The iodine and the dichroic dye in the polarizing film exhibit deflection performance by being oriented in a binder. Iodine and dichroic dye are preferably oriented along the binder molecule or the dichroic dye is oriented in one direction by self-organization such as liquid crystal.

Commercially available polarizers (polarizing films) are generally produced by immersing a stretched polymer in a solution of iodine or a dichroic dye in a bath and infiltrating an iodine or a dichroic dye in a binder.

Commercially available polarizers have iodine or dichroic pigments distributed on the surface of the polymer at about 4 μm (about 8 μm in total), and at least 10 μm is required to obtain sufficient polarization performance. The degree of penetration can be controlled by the solution concentration of the iodine or dichroic dye, the temperature of the bath and the immersion time.

As mentioned above, it is preferable that the minimum of binder thickness is 10 micrometers. The thinner the upper limit of the thickness, the better. It is preferable that it is currently commercially available polarizing plate (about 30 micrometers) or less, 25 micrometers or less are preferable, and 20 micrometers or less are more preferable. If the thickness is 20 µm or less, the light leakage phenomenon is not observed by the 17-inch liquid crystal display device.

As the binder of the polarizing film, any polymer which can be crosslinked by itself or a polymer which is crosslinked by a crosslinking agent can be used. Examples of the polymer include the same polymer as described for the alignment film.

Most preferred are polyvinyl alcohol and modified polyvinyl alcohol.

About modified polyvinyl alcohol, it is described in each of Unexamined-Japanese-Patent No. 8-338913, 9-152509, and 9-316127.

Polyvinyl alcohol and modified polyvinyl alcohol may use 2 or more types together.

The binder of the polarizing film may be crosslinked.

The crosslinked binder can use a polymer which can be crosslinked by itself. A binder obtained by introducing a functional group into a polymer having a functional group or a polymer can be reacted between the binders by light, heat or pH change to form a polarizing film.

Moreover, you may introduce a crosslinked structure into a polymer with a crosslinking agent.

Crosslinking is generally carried out by applying a coating liquid containing a polymer or a mixture of a polymer and a crosslinking agent on a transparent support and then heating. Since durability can be ensured at the stage of the final product, the crosslinking treatment may be performed at any stage until the final polarizing plate is obtained.

As for the addition amount of the crosslinking agent of a binder, 0.1-20 mass% is preferable with respect to a binder. The orientation of a polarizing element and the moisture heat resistance of a polarizing film become favorable.

The polarizing film contains the crosslinking agent which did not react even after completion | finish of crosslinking reaction to some extent. However, it is preferable that it is 1.0 mass% or less in a polarizing film, and, as for the quantity of the remaining crosslinking agent, it is more preferable that it is 0.5 mass% or less. By doing so, even if the polarizing film is attached to the liquid crystal display device and left for a long time in a long-term use or a high temperature and high humidity atmosphere, the polarization degree does not decrease.

Regarding the crosslinking agent, there may be mentioned the description of the specification of US Reissue Patent No. 23297. Boron compounds (eg, boric acid, borax) can also be used as the crosslinking agent.

As the dichroic dye, an azo dye, a stilbene dye, a pyrazolone dye, a triphenylmethane dye, a quinoline dye, an oxazine dye, a thiazine dye or an anthraquinone dye is used. It is preferable that a dichroic dye is water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl).

As an example of a dichroic dye, the compound of Unexamined-Japanese-Patent No. 2001-1745, page 58 (the date of publication March 15, 2001) is mentioned, for example.

In order to raise the contrast ratio of a liquid crystal display device, it is preferable that the transmittance | permeability of a polarizing plate is high, and it is preferable that a polarization degree is also high. It is preferable that the transmittance | permeability of a polarizing plate exists in 30 to 50% of range in the light of wavelength 550nm, It is more preferable to exist in 35 to 50% of range, It is most preferable to exist in 40 to 50% of range. The degree of polarization is preferably in the range of 90 to 100% with light having a wavelength of 550 nm, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100%.

It is also possible to arrange | position a polarizing film and an optically anisotropic layer or a polarizing film and an oriented film through an adhesive agent. As the adhesive, a polyvinyl alcohol-based resin (containing acetacetyl group, sulfonic acid group, carboxyl group, modified polyvinyl alcohol by oxyalkylene group) or a boron compound aqueous solution can be used. Polyvinyl alcohol-type resin is preferable. It is preferable that the thickness of an adhesive bond layer exists in the range of 0.01-10 micrometers after drying, and it is especially preferable to exist in the range which is 0.05-5 micrometers.

[Production of Polarizing Plate]

The polarizing film is preferably dyed with iodine or a dichroic dye after stretching the binder (stretching method) or rubbing (rubbing method) by inclining the binder 10 to 80 degrees with respect to the longitudinal direction (MD direction) of the polarizing film from the viewpoint of yield. . It is preferable to extend | elongate an inclination-angle so that the inclination-angle may be made to the angle which the transmission axis of the two polarizing plates attached to both sides of the liquid crystal cell which comprises LCD, and the longitudinal or horizontal direction of a liquid crystal cell make.

Typical inclination angle is 45 degrees. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective and semi-transmissive LCDs, so that the stretching direction can be arbitrarily adjusted according to the LCD design.

In the stretching method, the stretching ratio is preferably 1.1 to 30.0 times, more preferably 1.5 to 10.0 times. Stretching can be performed by dry stretching in air. Further, wet stretching in a state of being immersed in water may be performed. The stretching ratio of dry stretching is preferably 1.2 to 5.0 times, and the stretching ratio of wet stretching is preferably 3.0 to 10.0 times. An extending process may be divided into several times including diagonal stretch. By dividing into several circuits, it can extend | stretch more uniformly even in high magnification extending | stretching. You may perform some extending | stretching (a grade which prevents shrinkage of the width direction) before or after diagonal stretch.

Stretching can be performed by performing tenter stretching in biaxial stretching by different steps. The said biaxial stretching is the same as the extending | stretching method performed by normal film film manufacture. In biaxial stretching, since it is stretched at different speeds left and right, it is necessary to make the thickness of the binder film before stretching differ from right to left. In the casting film production, the taper is attached to the die to make a difference in the flow rate of the binder solution.

As described above, a binder film 10 to 80 degrees inclined to the MD direction of the polarizing film is produced.

In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment step 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 or nylon, or polyester fibers. Generally, it carries out by rubbing about several times using the cloth which averaged the fiber which was uniform in length and thickness using the fiber which was planted on the average.

It is preferable to implement using the rubbing roll whose roundness, cylinder degree, and a deviation (eccentricity) of a roll itself are all 30 micrometers or less. The wrap angle of the film relative to the rubbing roll is preferably 0.1 to 90 °. However, as described in Japanese Unexamined Patent Publication No. Hei 8-160430, it is also possible to obtain stable rubbing treatment by winding 360 degrees or more.

When rubbing a long film, it is preferable to convey a film by the conveying apparatus at the speed of 1-100 m / min in the state of constant tension. It is preferable that the rubbing roll is free to rotate in the horizontal direction with respect to the film advancing direction for setting an arbitrary rubbing angle. It is desirable to select an appropriate rubbing angle in the range of 0 to 60 °. 40-50 degrees is preferable when using for a liquid crystal display device. 45 ° is particularly preferred.

Then, the transparent protective film is disposed on both sides of the polarizing film (optical compensation sheet / polarizing film / other transparent protective film of the present invention or optical compensation sheet / polarizing film / optical compensation sheet of the present invention) of the present invention.

The transparent protective film may form an antireflection film having antifouling properties and scratch resistance on its outermost surface. As the antireflection film, any conventionally known one can be used.

The polarizing plate of this invention is manufactured as mentioned above.

The polarizing plate of the present invention using the optical compensation sheet of the present invention is advantageously used for a liquid crystal display device, particularly a transmissive liquid crystal display device.

The transparent protective film is surface treated to improve the adhesion with the polarizing film. In the case where the polarizing film is polyvinyl alcohol, the protective film is preferably hydrophilized. It is preferable that a protective film is damped by a water washing process before adhering with a polarizing film, and it is preferable that the contact angle with respect to the water on the surface of a protective film is 30 degrees or more from a viewpoint that a water droplet remains. If it is less than 30 °, the entire surface of the protective film is wet with water, making it very difficult to remove moisture. In particular, it is preferable to control the contact angle of the polarizing film side surface of a protective film on the optical characteristic of a polarizing plate.

In the 4th and 5th aspect of this invention, the optical compensation sheet of this invention using the cellulose acetate film is used for one of the two protective films of a polarizing plate. You may use a normal cellulose acetate film for the other protective film.

The slow axis of the transparent protective film and the transmission axis of the polarizing film are arranged to be substantially vertical or parallel.

Moreover, it turned out that moisture permeability of a protective film is important for productivity of a polarizing plate. The polarizing film and the protective film are adhered with an aqueous adhesive, and this adhesive solvent is dried by diffusing into the protective film. The higher the moisture permeability of the protective film, the faster the drying and the higher the productivity. However, the higher the moisture permeability of the protective film, the lower the polarization performance due to moisture entering the polarizing film due to the use environment of the liquid crystal display (high humidity).

The moisture permeability of the optical compensation sheet is determined by the thickness, free volume or hydrophilicity of the polymer film (and the polymerizable liquid crystal compound).

When using an optical compensation sheet as a protective film of a polarizing plate, it is preferable that the moisture permeability of an optical compensation sheet exists in the range of 100-1000 (g / m <2>) / 24hrs, and is in the range of 300-700 (g / m <2>) / 24hrs. More preferably.

The thickness of the optical compensation sheet can be adjusted by the lip flow rate and the line speed, or the stretching and the compression in the case of film production of the cellulose acylate film. Since moisture permeability differs according to the main raw material to be used, it is possible to make it a preferable range by thickness adjustment.

The free volume of the optical compensation sheet can be adjusted by drying temperature and time in the case of film production. Also in this case, since moisture permeability differs according to the main material to be used similarly, it is possible to set it as a preferable range by free volume adjustment.

The hydrophilicity of an optical compensation film can be adjusted with an additive. The moisture permeability is increased by adding a hydrophilic additive in the free volume, and conversely, the moisture permeability can be lowered by adding a hydrophobic additive.

By adjusting the moisture permeability of the optical compensation sheet, it becomes possible to manufacture a polarizing plate having optical compensation ability at low productivity with high productivity.

As mentioned above, the binder film extended | stretched 10 to 80 degree with respect to MD direction of a polarizing film is manufactured.

In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment step of LCD can be applied. That is, the orientation is obtained by rubbing the surface of the film in a certain direction using paper, gauze, felt, rubber or nylon, or polyester fibers. Generally, it carries out by rubbing about several times using the cloth which averaged the fiber which was uniform in length and thickness using the fiber which was planted on the average.

It is preferable to implement using the rubbing roll whose roundness, cylinder degree, and a deviation (eccentricity) of a roll itself are all 30 micrometers or less. The wrap angle of the film relative to the rubbing roll is preferably 0.1 to 90 °. However, as described in Japanese Unexamined Patent Publication No. Hei 8-160430, it is also possible to obtain stable rubbing treatment by winding 360 degrees or more.

When rubbing a long film, it is preferable to convey a film by the conveying apparatus at the speed of 1-100 m / min in the state of constant tension. It is preferable that the rubbing roll is free to rotate in the horizontal direction with respect to the film advancing direction for setting an arbitrary rubbing angle. It is desirable to select an appropriate rubbing angle in the range of 0 to 60 °. 40-50 degrees is preferable when using for a liquid crystal display device. 45 ° is particularly preferred.

Then, the transparent protective film is disposed on both sides of the polarizing film (optical compensation sheet / polarizing film / other transparent protective film of the present invention or optical compensation sheet / polarizing film / optical compensation sheet of the present invention) of the present invention.

The transparent protective film may form an antireflection film having antifouling properties and scratch resistance on its outermost surface. As the antireflection film, any conventionally known one can be used.

The polarizing plate of this invention is manufactured as mentioned above.

The polarizing plate of the present invention using the optical compensation sheet of the present invention is advantageously used for a liquid crystal display device, particularly a transmissive liquid crystal display device.

Next, the liquid crystal display device of the present invention, in particular, the transmissive liquid crystal display device and its manufacture will be described in detail.

<LCD display device>

The liquid crystal display device of the present invention is a liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, and a polarizing plate consisting of a polarizing film and two transparent protective films disposed on both sides thereof, and between the liquid crystal cell and the polarizing film. At least one of the two transparent protective films arranged in the above is characterized in that the optical compensation sheet of the present invention is used. That is, the liquid crystal display device of this invention uses the polarizing plate of this invention mentioned above as a polarizing plate.

The preferable aspect of the optically anisotropic layer in each liquid crystal mode is demonstrated below.

In a preferred embodiment of the optically anisotropic layer in each liquid crystal mode, the optical compensation sheet polarizing plate of the present invention can advantageously optically compensate.

(TN mode liquid crystal display)

The liquid crystal cell of the TN mode is most often used as a color TFT liquid crystal display device, and has been described in a number of documents. The alignment state of the liquid crystal cell in the black display of the TN mode is in the alignment state in which the rod-like liquid crystalline molecules occur in the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the substrate of the cell.

(OCB Mode Liquid Crystal Display)

The liquid crystal cell of the OCB mode is a liquid crystal cell of the bend alignment mode in which rod-like liquid crystalline molecules are oriented substantially in opposite directions (symmetrically) at the upper and lower portions of the liquid crystal cell. Examples of the liquid crystal display device using the liquid crystal cell in the bend alignment mode include the devices disclosed in the specifications of US Pat. Nos. 4583825 and 5410422. Since the rod-like liquid crystalline molecules are symmetrically aligned at the top and bottom of the liquid crystal cell, the liquid crystal cell in the bend alignment mode has a magneto-optical compensation function. For this reason, this liquid crystal mode is also called OCB (Optically Compensatory Bend) liquid crystal mode.

Similarly to the TN mode, in the OCB mode liquid crystal cell, in the black display, the alignment state among the liquid crystal cells is in the alignment state in which the rod-like liquid crystalline molecules occur in the center of the cell and the rod-like liquid crystalline molecules are in the vicinity of the substrate of the cell.

(VA mode liquid crystal display)

In the liquid crystal cell of VA mode, the rod-shaped liquid crystalline molecules are substantially vertically aligned when no voltage is applied.

In the VA mode liquid crystal cell, (1) bar-shaped liquid crystal cells are oriented substantially vertically when no voltage is applied, and are substantially horizontally aligned when voltage is applied (JP-A-2). In addition to (176), (2) the liquid crystal cell of (MVA mode) (SID97, Digest of tech.Papers (Preliminary) 28 (1997) 845 described) multi-domain VA mode for viewing angle enlargement, (3 Liquid crystal cell (n-ASM mode) notices 58-59 (1998) of a liquid crystal cell in which a rod-shaped liquid crystalline molecule is substantially vertically aligned when no voltage is applied, and a twisted multi-domain orientation is applied when voltage is applied. ) And (4) a liquid crystal cell in SURVAIVAL mode.

(Other liquid crystal display device)

The liquid crystal display of the ECB mode and the STN mode can be optically compensated in the above manner.

In the liquid crystal display device of the present invention, it is preferable that the liquid crystal cell is a liquid crystal cell of TN mode, VA mode, MVA mode, n-ASM mode or OCB mode in that the effect of the optical compensation sheet of the present invention can be exhibited to the maximum.

In the liquid crystal cell of the TN mode, the rod-like liquid crystalline molecules are substantially horizontally aligned and twist-oriented at 60 to 120 ° when no voltage is applied. The liquid crystal cell of the TN mode is most often used as a color TFT liquid crystal display device and has been described in a number of documents.

The present inventors have improved the cellulose acetate film disclosed in the specification of European Patent 0911656A2, and the optical compensation sheet which can optically compensate the liquid crystal cell without side effects while maintaining the conventional thickness or thinner. 5th aspect) was completed.

By adjusting the type and amount of additives (specifically, aromatic compounds having two aromatic rings) or manufacturing conditions (for example, stretching conditions of the film) to the cellulose acetate film, the Re retardation value is 5 to 100 nm. And a cellulose acetate film having an Rth retardation value of 70 to 400 nm. This cellulose acetate film has sufficient optical anisotropy in order to optically compensate a liquid crystal cell. Moreover, by performing surface treatment on this cellulose acetate film, the contact angle with respect to water is 30 degrees or more and 70 degrees or less, and the optical compensation sheet which consists of a cellulose acetate film suitable for polarizing plate processing is obtained.

Moreover, a polarizing plate consists of a polarizing film and the protective film arrange | positioned at both sides. The polarizing film is obtained by adsorbing an iodine or a dichroic dye on a stretched orientation of polyvinyl alcohol, and the protective film generally consists of a cellulose acetate film. When the cellulose acetate film is used as one protective film of the polarizing plate, an optical compensation function can be added to the polarizing plate without increasing the number of components of the polarizing plate. At this time, in this invention, since the contact angle with respect to the water of the surface of a cellulose acetate film is 30 degrees or more, the yield in a polarizing plate process process and adhesiveness with a polarizing film can be made compatible.

Moreover, when the cellulose acetate whose acetylation degree is less than 59.0 is used, the said optical anisotropy can be easily achieved, but the physical property as a cellulose acetate film falls. In the present invention, by using cellulose acetate having an acetylation degree of 59.0 to 61.5% to achieve the retardation value by other means (adjustment of the additives or manufacturing conditions), both the optical anisotropy and the physical properties are excellent, and the polarizing film and The cellulose acetate film excellent in the adhesiveness of is obtained.

The optical compensation sheet made of the cellulose acetate film and the polarizing plate using the cellulose acetate film as a protective film are particularly advantageously used for OCB (Optically Compensatory Bend), VA (Vertically Aligned) or TN (Twisted Nematic) type liquid crystal displays. Can be.

The optical compensation sheet of the first aspect and the second aspect of the present invention is particularly advantageous for a TN type or an IPS type liquid crystal display device. The optical compensation sheets of the fourth and fifth aspects of the present invention are particularly advantageous for VA type (including MVA type and n-APS type) and OCB type liquid crystal display devices.

(Example)

(1st aspect, 2nd aspect)

Example 1

(Production of cellulose acylate film)

The following composition was thrown into the mixing tank, it stirred, heating, and each component was dissolved and the cellulose acylate solution was prepared.

Cellulose Acylate Solution Composition Acetylation degree 60.9% cellulose acetate 100 parts by mass triphenyl phosphate (plasticizer) 7.8 parts by mass biphenyl diphenyl phosphate (plasticizer) 3.9 parts by mass methylene chloride (first solvent) 295 parts by mass methanol (second solvent) 68 parts by mass 2 parts by mass of butanol (third solvent)

16 mass parts of following retardation increasing agents, 80 mass parts of methylene chlorides, and 20 mass parts of methanol were thrown into another mixing tank, and it stirred, heating, and prepared the retardation increasing agent solution.

25 mass parts of retardation increasing agent solutions were mixed with 474 mass parts of cellulose acylate solutions, and it fully stirred, and dope was prepared. The addition amount of the retardation increasing agent was 3.5 mass parts with respect to 100 mass parts of cellulose acetates.

The obtained dope was cast using the drum softener. After the film surface temperature on a drum became 40 degreeC, it dried for 1 minute by the warm air of 70 degreeC, peeled a film from the drum with volatile matter 55%, and immediately after that, the film was dried for 1 minute by the drying air of 140 degreeC, It dried again by 130 degreeC dry air for 15 minutes, and produced the cellulose acylate film (thickness: 80 micrometers) whose residual solvent amount is 0.3 mass%.

Optical characteristics were measured about the produced cellulose acylate film (CAF-01). The results are shown in Table 1.

In addition, the optical characteristic measured the Re retardation value and Rth retardation value in wavelength 550nm using the ellipsometer (M-150, Nippon Bunco Co., Ltd. product).

The produced cellulose acylate film was immersed in 2.0 N potassium hydroxide solution (25 ° C) for 2 minutes, neutralized with sulfuric acid, washed with pure water, and dried. The surface energy of this cellulose acylate film was found to be 63 mN / m by the contact angle method.

(Formation of alignment film)

The coating liquid of the following composition was apply | coated 28 mL / m <2> on the produced cellulose acylate film with the wire bar coater of # 16. It dried for 60 second with the warm air of 60 degreeC, and 150 second with the warm air of 90 degreeC again.

Next, the rubbing process was performed to the formed film in the direction parallel to the longitudinal direction of a cellulose acylate film.

Alignment film coating liquid composition 10 parts by mass of the following modified polyvinyl alcohol 371 parts by mass Methanol 119 parts by mass Glutalaldehyde (crosslinking agent) 0.5 parts by mass

(Formation of optically anisotropic layer)

41.01 g of the following disk type liquid crystalline compound, ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4.06 g, cellulose acetate butyrate (CAB551-0.2, manufactured by Eastman Chemical Co., Ltd.) 0.90 g, cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.) 0.23 g, photopolymerization initiator (Irugacure 907, manufactured by Chiba Chemical Co., Ltd.) 1.35 g, sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) ) The coating liquid which melt | dissolved 0.45g in 102g methyl ethyl ketone was apply | coated by the wire bar of # 3.6. This was heated for 2 minutes in the constant temperature zone of 130 degreeC, and the disk shaped liquid crystalline compound was orientated. Next, UV irradiation was performed for 1 minute using a 120 W / cm high pressure mercury lamp in an atmosphere of 60 ° C to polymerize the discotic liquid crystalline compound. Thereafter, the mixture was allowed to cool to room temperature. In this way, an optically anisotropic layer was formed to produce an optical compensation sheet (KH-01).

The Re retardation value of the optically anisotropic layer measured at the wavelength of 546 nm was 43 nm. In addition, the angle (inclined angle) between the disk surface and the transparent support body (cellulose acylate film) surface was 42 degrees on average.

Example 2

(Production of cellulose acylate film)

The following composition was thrown into the mixing tank, it stirred, heating, and each component was dissolved and the cellulose acylate solution was prepared.

Cellulose Acylate Solution Composition 16 parts by mass of cellulose acetate 100 parts by mass of acetylation degree 60.7% polyether urethane (B-326, Sumitomo Biureurethane Co., Ltd., Desmochol 176) methylene chloride (first solvent) 290 parts by mass methanol (second solvent) 73 parts by mass 2 parts by mass of 1-butanol (third solvent)

16 mass parts of retardation increasing agent used in Example 1, 80 mass parts of methylene chloride, and 20 mass parts of methanol were thrown into another mixing tank, and it stirred, heating, and prepared the retardation increasing agent solution.

15 parts by mass of the retardation synergist solution was mixed with 484 parts by mass of the cellulose acylate solution, and sufficiently stirred to prepare dope. The addition amount of the retardation increasing agent was 2.0 mass parts with respect to 100 mass parts of cellulose acetates.

The obtained dope was cast using the drum softener. After the film surface temperature on the drum became 40 degreeC, it dried for 1 minute by the warm air of 65 degreeC, and peeled off the drum which the residual solvent was 60%. Next, the film was stretched by a tenter in the state of 20% in the width direction while drying at 130 ° C. for 5 minutes, and the amount of residual solvent was 5% by mass. Then, the film was stretched 18% in the longitudinal direction in that state and dried at 140 ° C. for 10 minutes to prepare a cellulose acylate film (thickness: 40 μm) having a residual solvent of 0.3% by mass.

Optical characteristics were measured about the produced cellulose acylate film (CAF-02). The results are shown in Table 1.

In addition, the optical characteristic measured the Re retardation value and Rth retardation value in wavelength 550nm using the ellipsometer (M-150, Nippon Bunco Co., Ltd. product).

The surface treatment was performed to the cellulose acylate film like Example 1, the alignment film and the optically anisotropic layer were formed, and the optical compensation sheet (KH-02) was produced.

Comparative Example 1

(Production of cellulose acylate film)

The following composition was thrown into the mixing tank, it stirred, heating, and each component was dissolved and the cellulose acylate solution was prepared.

Cellulose Acylate Solution Composition Acetylation degree 60.9% cellulose acetate 100 parts by mass triphenyl phosphate (plasticizer) 7.8 parts by mass biphenyl diphenyl phosphate (plasticizer) 3.9 parts by mass methylene chloride (first solvent) 300 parts by mass methanol (second solvent) 54 parts by mass 11 parts by mass of butanol (third solvent)

This cellulose acylate solution was doped as it was and cast using a bend softener. After the film surface temperature on a bend became 40 degreeC, it dried for 1 minute by 40 degreeC warm air, and peeled off the film from the bend in the state of volatile matter 30%. Subsequently, the film was dried with a drying air at 100 ° C. for 30 minutes to prepare a cellulose acylate film (thickness: 80 μm) having a residual solvent amount of 0.9% by mass.

Optical characteristics were measured about the produced cellulose acylate film (CAF-H1). The results are shown in Table 1.

film Amount of synergist Re Rth Vmax Vmin Example 1 CAF-01 Part 3.5 8 nm 80 nm 2.33 2.28 Example 2 CAF-02 Part 2.5 4 nm 90 nm 2.35 2.29 Comparative Example 1 CAF-H1 none 4 nm 48 nm 2.12 2.14 Note: The speed of sound was measured using the Nomura Corporation make SST-2500 type.

Example 4

Iodine is adsorbed on the stretched polyvinyl alcohol film to produce a polarizing film, and the cellulose acylate film (CAF-01) is polarized on the optical compensation sheet (KH-01) produced in Example 1 using a polyvinyl alcohol-based adhesive. It adhere | attached on one side of a polarizing film so that it might become a film side. The transmission axis of the polarizing film and the slow axis of the optical compensation sheet (KH-01) were arranged to be parallel to each other.

A saponification process was carried out to the commercially available cellulose triacetate film (Fujitak TD80UF, manufactured by Fujishashin Film Co., Ltd.), and adhered to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. In this way, a polarizing plate was produced.

Example 5

Iodine is adsorbed on the stretched polyvinyl alcohol film to produce a polarizing film, and the cellulose acylate film (CAF-02) is polarized on the optical compensation sheet (KH-02) produced in Example 2 using a polyvinyl alcohol-based adhesive. It adhere | attached on one side of a polarizing film so that it might become a film side. The transmission axis of the polarizing film and the slow axis of the optical compensation sheet (KH-02) were arranged to be parallel to each other.

A saponification process was carried out to the commercially available cellulose triacetate film (Fujitak TD80UF, manufactured by Fujishashin Film Co., Ltd.), and adhered to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. In this way, a polarizing plate was produced.

Comparative Example 2

Iodine was adsorbed to the stretched polyvinyl alcohol film to prepare a polarizing film, and the cellulose acylate film produced in Comparative Example 1 was attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. The transmission axis of a polarizing film and the slow axis of a cellulose acylate film (CAF-H1) were arrange | positioned so that it might become perpendicular.

A saponification process was carried out to the commercially available cellulose triacetate film (Fujitak TD80UF, manufactured by Fujishashin Film Co., Ltd.), and adhered to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. In this way, a polarizing plate was produced.

Example 7

The pair of polarizing plates formed on the liquid crystal display device (6E-A3, manufactured by Sharp Co., Ltd.) using a TN type liquid crystal cell was removed, and the polarizing plate produced in Example 4 was replaced with the optical compensation sheet (KH-01). It adhere | attached one by one to the observer side and the backlight side using an adhesive so that it might become a liquid crystal cell side. It was arrange | positioned so that the transmission axis of an observer side polarizing plate and the transmission axis of a backlight side polarizing plate may orthogonally cross.

About the produced liquid crystal display device, the viewing angle was measured in 8 steps from a black display (L1) to a white display (L8) using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). The results are shown in Table 2.

Example 8

The pair of polarizing plates formed on the liquid crystal display device (6E-A3, manufactured by Sharp Co., Ltd.) using a TN type liquid crystal cell was removed, and the polarizing plate produced in Example 5 was replaced with the optical compensation sheet (KH-02). It adhere | attached one by one to the observer side and the backlight side using an adhesive so that it might become a liquid crystal cell side. It was arrange | positioned so that the transmission axis of an observer side polarizing plate and the transmission axis of a backlight side polarizing plate may orthogonally cross.

About the produced liquid crystal display device, the viewing angle was measured in 8 steps from a black display (L1) to a white display (L8) using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). The results are shown in Table 2.

Comparative Example 3

For a liquid crystal display device (6E-A3, manufactured by Sharp Co., Ltd.) using a TN type liquid crystal cell, a black display (L1) to white display (L8) using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM) The viewing angle was measured in step 8. The results are shown in Table 2.

LCD Display Viewing angle (contrast ratio is more than 10 and there is no black-level inversion) Prize Ha Right and left Example 7 70 ° 45 ° 160 ° Example 8 75 ° 45 ° 160 ° Comparative Example 3 15 ° 25 ° 37 ° (Note) black-level inversion: Inversion between L1 and L2

Example 10

A pair of polarizing plates formed on a 20-inch liquid crystal display device (LC-20V1 manufactured by Sharp Co., Ltd.) using a TN type liquid crystal cell was removed, and the polarizing plates produced in Example 4 were replaced with optical compensation sheets (KH). Each sheet was attached to the observer side and the backlight side by using an adhesive such that -01) was the liquid crystal cell side. It was arrange | positioned so that the transmission axis of an observer side polarizing plate and the transmission axis of a backlight side polarizing plate may orthogonally cross.

The backlight was turned on continuously for 5 hours at 25 ° C. and 60% relative humidity, and the light leakage was evaluated by visually observing the entire black display state in the dark room. As a result, no light leakage was observed on the display screen of the liquid crystal display device.

Example 11

A polarizing plate was mounted on a liquid crystal display device in the same manner as in Example 10 except that the polarizing plate produced in Example 5 was used.

Light leakage was evaluated in the same manner as in Example 10. As a result, no light leakage was observed on the display screen of the liquid crystal display device.

[Comparative Example 4]

Except having used the polarizing plate produced by the comparative example 2, it carried out similarly to Example 10, and mounted the polarizing plate in the liquid crystal display device.

Light leakage was evaluated in the same manner as in Example 10. As a result, a frame type light leakage was observed on the display screen of the liquid crystal display device.

(Third aspect)

Example 12

<Production of Transparent Supports>

(Adjustment of Particulate Dispersion (RL-1))

The solution which consists of the following composition was prepared, and it disperse | distributed so that it might become a volume average particle diameter of 80 nm with the attritor, and the microparticle dispersion was obtained. When the particle size distribution of the obtained fine particle dispersion was measured, particles having a particle size of 500 nm or more were 0%.

Here, the volume average particle diameter was measured by "particle size distribution measuring apparatus LA920 (made by Horiba Corporation)."

ㆍ Particulate dispersion (RL-1) composition

Hydrophobic silica (brand name "AEROSIL R812" (methyl modified substance, primary particle size 7nm: Nippon Aerosil Co., Ltd.) 2.00 parts by mass

2.00 parts by mass of cellulose triacetate having an acetylation degree of 60.7% (6-position substitution degree of 0.90)

0.16 parts by mass of triphenylphosphate

0.08 parts by mass of biphenyldiphenylphosphate

Methylene chloride 78.70 parts by mass

14.20 parts by mass of methanol

2.86 parts by mass of 1-butanol

(Adjustment of cellulose acylate solution (A-1))

The mixture which consists of the following composition was stirred and dissolved, and the cellulose acylate solution (A-1) was adjusted.

ㆍ Cellulose Acylate Solution (A-1) Composition

89.3 parts by mass of cellulose triacetate with 60.7% acetylation degree (0.90 substitution degree)

7.1 parts by mass of triphenylphosphate

3.6 parts by mass of biphenyl diphenyl phosphate

300 parts by mass of methylene chloride

Methanol 54 parts by mass

11 parts by mass of 1-butanol

The retardation regulator solution composition of the following composition was heat-stirred and the retardation regulator solution (RE-1) was prepared.

ㆍ Retardation Adjuster Solution (RE-1) Composition

12 parts by mass of 2-hydroxy-4-benzyloxybenzophenone

2,4-benzyloxybenzophenone 4 parts by mass

Methylene chloride 82.2 parts by mass

14.8 parts by mass of methanol

3.0 parts by mass of 1-butanol

(Preparation of dope)

After adding 15.3 mass parts of microparticle dispersions (RL-1) to 474 mass parts of cellulose acylate solutions (A-1), and fully stirring, 22 mass parts of retardation regulator solution (RE-1) were added, fully stirred, and room temperature again. After cooling the non-uniform gel-like solution obtained by leaving it to stand at (25 degreeC) for 3 hours at -70 degreeC for 6 hours, it heated and stirred at 50 degreeC and obtained the dope which melt | dissolved completely.

Next, the obtained dope was filtered with a filter paper (manufactured by Toyoji Co., Ltd., # 63) having an absolute filtration accuracy of 0.01 mm at 50 ° C., followed by further filter filtration and defoaming with a filter paper (FH025, manufactured by Paul Co., Ltd.) having an absolute filtration accuracy of 0.0025 mm. Dope was prepared.

(Solution flexible method)

As mentioned above, the dope obtained by the process of preparing a cellulose acylate solution was cast | flow_spreaded using the bend softener, and the process of film-forming a cellulose acylate film from the cellulose acylate solution was performed.

As the metal support (flexible bend), one made of stainless steel and having a width of 2 m and a length of 56 m (area 112 m 2) was used. The arithmetic mean roughness Ra of the metal support was 0.006 µm, the maximum height Ry was 0.06 µm, and the ten-point average roughness Rz was 0.009 µm. Each measurement of arithmetic mean roughness Ra, maximum height Ry, and 10-point average roughness Rz was based on JIS B 0601.

The softened dope was dried at a wind speed of 0.5 m / s or less for 1 second immediately after the softening, and then at a wind speed of 15 m / s. The temperature of the drying wind was 50 degreeC.

The amount of residual solvent of the film at the time of peeling off from a casting bend was 230 mass%, and the film temperature was -6 degreeC. The average drying rate until peeling off the cast bend was 744 mass% / min. In addition, the gelation temperature of dope at the time of peeling was about 10 degreeC.

After the film surface temperature on the metal support became 40 degreeC, it dried for 1 minute and peeled off, and the temperature of the drying wind was 120 degreeC. At this time, the width direction temperature distribution of the film was 5 degrees C or less, the average wind speed of drying was 5 m / s, the average value of the heat transfer coefficient was 25 kcal / m <2> * Hr * degreeC, and the width direction distribution of the film was all within 5%. In addition, the pin tenter supporting part in a drying zone did not let a dry hot wind directly contact with a wind blowing device.

Next, the process of extending | stretching a cellulose acylate film was performed. That is, the film was transversely stretched at a stretching ratio of 25% using a tenter under the condition of 130 ° C in the state of a film having a residual solvent amount of 15% by mass, and held at 50 ° C for 30 seconds with the width after stretching, and then the clip was pulled out. The solvent evaporated while peeling off and winding was 97 mass% of the initial amount of solvent. The dried film is dried by a drying wind at 145 ° C in the drying step to be transported with a roller again, and then wound around 0.35% by mass of solvent and 0.8% by mass of water when the humidity and temperature are adjusted and wound as a transparent support. A cellulose acylate film (CA-1) (thickness 65 µm) was obtained.

When the retardation was measured about the obtained cellulose acylate film (CA-1), retardation (Rth) of the thickness direction was 61 nm and in-plane retardation (Re) was 6 nm.

[Comparative Examples 12-1 to 12-3]

(Comparative Example 12-1)

In Example 12, the dispersion conditions of the dispersion of the fine particle dispersion (RL-1) were changed to adjust a dispersion having an average particle diameter of 200 nm of the dispersed particles in the dispersion. The particle | grains of 500 nm or more of the dispersion at this time were 20 volume%. Except having used this dispersion, it carried out similarly to Example 12, and produced the cellulose acylate film (CAR1-1) of 65 micrometers in film thickness.

(Comparative Example 12-2)

In Example 12, a cellulose acylate film (CAR1-2) having a thickness of 65 µm was produced in the same manner as in Example 12, except that the average wind speed of the dry air in the flexible film production was changed to 25 m / min and the temperature was 60 ° C. .

(Unevenness of film surface)

The bend side surface shape of each sample of obtained cellulose acylate film CA-1 and Comparative Examples 12-1 to 12-2 was measured. The results are shown in Table 1. Table 3 also shows the results of the evaluation of the following optical and mechanical properties.

(Evaluation Method of Optical Characteristics)

ㆍ Retardation value

Re-retardation value (Re550) and Rth retardation value (Rth550) at wavelength 550nm were measured using the ellipsometer (M-150, Nihon Bunco Co., Ltd. product).

ㆍ Surface axis misalignment and standard deviation

The axis shift angle was measured with the automatic birefringence meter (KOBRA-21ADH, an oji measuring apparatus). Each measurement calculated | required the average value in ten points of the width direction. Standard deviation was also obtained for the slow axis angle.

Haze

Haze was measured using a haze meter (1001DP type, manufactured by Nihon Denshoku Kogyo Co., Ltd.). 5 points | pieces were measured per sample of film, and the average value was employ | adopted.

(Method of Evaluating Mechanical Characteristics)

ㆍ Curl

Culch was measured according to the National Institute of Standards (ANSI / ASCPH 1.29-1985, Method-A). The polymer film is cut out to a size of 35 mm in the width direction and 2 mm in the longitudinal direction, and then attached to the curl plate. This is controlled at a temperature of 25 ° C. and a relative humidity of 65% for 1 hour, and then the curl is read. And similarly, a polymer film is cut out to the magnitude | size of 2 mm in width direction, and 35 mm in length direction, and is attached to a curl plate. This is controlled at a temperature of 25 ° C. and a relative humidity of 65% for 1 hour, and then the curl is read. It measured in two directions of the width direction and the longitudinal direction, and made the large value of both into culches. Culch is shown by the inverse of the radius of curvature m.

ㆍ tear strength

A film is cut | disconnected to width 65mm x length 50mm, and a sample is produced. Humidity was controlled for 2 hours or more in a room with a temperature of 30 ° C and a relative humidity of 85%, and the load (g) required for tearing was measured using a light load tear strength tester manufactured by Toyo Seiki Co., Ltd. according to ISO6383 / 2-1983. Obtained.

Cellulose acylate film Face Ra (μm) Rz (μm) Ra / Rz ratio Ry (μm) Sm (㎛) Re / Rth (nm) Ground shaft angle deviation (°) Standard deviation (°) Haze Curl / m Tear strength (g) Example 12 CA-1 0.005 0.014 0.367 0.022 0.150 6/61 0.5 0.3 0.2 -2 12 Comparative Example 12-1 CAR1-1 0.008 0.085 0.094 0.555 0.300 7/63 0.6 1.8 1.3 -One 10 Comparative Example 12-2 CAR1-2 × (Poor planarity) 6/61 Deviation is large 0.3 Flatness 4 to 11

As shown in the said Table 3, the cellulose acylate film (CA-1) of Example 12 was favorable in surface shape, and the shape of the surface was a thing with constant concavo-convex shape by the value of Table 3. Moreover, the retardation value, the slow axis angle shift | offset, the standard deviation, the haze value optical characteristics, and the mechanical characteristics of curl and tear strength were also favorable. On the other hand, in Comparative Example 12-1, the variation of the surface irregularities appeared, and the haze value became large. In Comparative Example 12-2, the planarity and planarity were remarkably decreased.

As mentioned above, the transparent support body for optical compensation sheets which maintained the mechanical characteristic was obtained, containing the ultra-fine particle dispersion which does not contain 500 nm or more particle | grains in a film with a film thickness of 65 micrometers, and suppressing a haze becoming large.

(Comparative Example 12-3)

In Example 12, a film having a residual solvent amount of 15% by mass as a stretching holding condition using a tenter was transversely stretched at a stretching ratio of 25% using a tenter under a condition of 130 ° C, and held at 130 ° C for 15 seconds with the width after stretching. A cellulose acylate film (CAR1-3) having a film thickness of 65 µm was produced in the same manner as in Example 12 except for the above procedure.

The uneven shape, optical properties, and mechanical properties of the obtained film surface were measured in the same manner as in Example 12 and Comparative Examples 12-1 to 12-2. In Comparative Example 12-3, the angle shift of the slow axis was large as 3.5. Moreover, surface shape, ground shaft angle shift | offset | difference, standard deviation, and haze fell.

(Alkaline saponification treatment)

The following alkali saponification process was performed to one surface of each film of the said Table 3, and the film sample of the comparative example 12-3.

That is, after passing a dielectric heating roll having a temperature of 60 ° C. on the film and raising the temperature to a film surface temperature of 40 ° C., an alkali solution (S-1) having the composition shown below was applied at a coating amount of 12 cc / m 2 using a rod coater, and then 110. It was hold | maintained for 10 second by the steam type far-infrared heater manufactured by Noritake Co., Ltd. heated to ° C. Subsequently, 4 cc / m <2> of pure water was apply | coated similarly using the rod coater. The film temperature at this time was 40 degreeC. Subsequently, water washing with a fountain coater and water removal with an air knife were repeated three times, followed by drying in a drying zone at 70 ° C. for 5 seconds.

ㆍ Alkaline Solution (S-1) Composition

8.6 parts by mass of potassium hydroxide

24.1 parts by mass of water

56.3 parts by mass of isopropanol

Surfactant _{(K-1: C 14 H} 29 O (CH 2 CH 2 O) 20 H) 1.0 parts by weight

10.0 parts by mass of propylene glycol

Bubble remover safinol DF110D (trade name, manufactured by Nisshin Chemical Co., Ltd.) 0.010 parts by mass

(Characteristics of Film after Hydrophilic Surface Treatment)

The following test was done about each created film, and the effect of alkali treatment was confirmed. The results are shown in Table 4.

(Contact angle with water)

Using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., CA-X type contact angle meter), liquid (1.0 mm in diameter) was made at the tip of the needle by using pure water in a liquid at 20 ° C / 65% RH. Droplets were made by contacting the film surface. The angle between the tangent to the liquid surface and the solid surface at the point where the solid liquid was in contact was used as the contact angle.

For each film, the contact angles at both ends and the center 9 positions were measured in the plane of 1 square meter to describe the upper limit value and the lower limit value. However, the range of ± 1 degree is the deviation range in the measurement, and is represented by the median.

(On the surface: foreign matter, cloudy)

It was cut out from the saponified film in a length of 1 m in the length direction at full width, and the sample was evaluated by the following criteria by observing the presence or absence of foreign matter and cloudiness with a naked eye and a magnifying glass while transmitting light on the shakasten.

： Foreign objects and blurring are not recognized at all (levels that 10 people evaluate and cannot recognize even one)

(Triangle | delta): Some foreign material and a blur generate | occur | produce (level evaluated by 2 to 5 people)

X: Foreign object and a lot of blur occur (level that ten people evaluate, and six or more recognize)

Sample No. Cellulose acylate film Contact angle with water (°) Surface area after treatment Example 12 FS-1 CA-1 34 Comparative Example 12-1 FSR1-1 CAR1-1 33 to 45 Comparative Example 12-2 FSR1-2 CAR1-2 33-44 × Comparative Example 12-3 FSR1-3 CAR1-3 33 to 43 ×

As shown in Table 4, the sheet | seat FS-1 of Example 1 was a uniform process in which the contact angle with water was 34 degree | times in the inside of 1 square meter, and the in-plane deviation was not seen. The occurrence of foreign matter or blur was not recognized in the whole surface of the film. In Comparative Example 1 (FSR1-1) having a large surface unevenness, the variation in the contact angle with water in the surface of 1 square meter was increased to 35 to 43 degrees. In addition, the surface was also deteriorated, and in particular, many foreign substances were seen. In addition, the comparative examples (FSR1-2 and FSR1-3) also had uneven saponification, and the contact angle with water was remarkably nonuniform.

As mentioned above, it became clear that the transparent support body in the optical compensation sheet of this invention of Example 12 is hydrophilized uniformly in surface inside.

(Formation of alignment film)

The alignment film coating liquid (O-1) of the following composition was apply | coated by the load coater at the application amount of 28 ml / m <2> on each transparent support body obtained by this hydrophilization surface treatment. It dried for 60 second with the warm air of 60 degreeC, and 150 second with the warm air of 90 degreeC again.

After drying, the pH of the coated surface was measured, and the value was 4.0. In addition, the pH value of the center and the left and right both ends positions in the coating width direction were in the range of 3.95-4.10.

Next, the rubbing treatment was performed in the longitudinal direction of each film subjected to the hydrophilization surface treatment.

ㆍ Oriental film coating liquid (O-1) composition

20 parts by mass of modified polyvinyl alcohol represented by the following formula

0.06 parts by mass citric acid

Glutalaldehyde 0.5 parts by mass

360 parts by mass of water

120 parts by mass of methanol

And the adhesive test of the orientation film was performed with respect to the transparent support body in which the obtained orientation film was formed as follows. The results are shown in Table 3.

(Evaluation method of orientation film adhesiveness)

According to JIS K-5400's checkerboard tape method, 100 1 mm × 1 mm cross hatch scales were used on the surface of the alignment layer under conditions of 25 ° C and 60% relative humidity. After leaving for 2 hours, the prescribed cellophane adhesive tape is attached and rubbed with an eraser to adhere to the coating film. Evaluation was made by measuring the number of graduations from which the alignment film was peeled off from the transparent support when it was peeled off at right angles to the coating film surface 2 minutes after the tape was attached.

◎: One which does not come off in 100

： Peeled off within two to 100

△: 100 to 10 peeled off

×: It is stripped more than ten in 100

(Formation of optically anisotropic layer)

Next, the optically anisotropic layer was formed with the following method about the transparent support body in which the oriented film was formed, and the optical compensation sheet was obtained.

That is, a discotic liquid crystal coating liquid (DA-1) having the following composition was applied onto the alignment film with a wire bar coater of # 4, heated in a high temperature bath at 125 ° C. for 3 minutes to orient the discotic liquid crystal, and then a high pressure mercury lamp was used. UV irradiation was carried out using 500 mJ / cm <2>, and it cooled to room temperature, and each optical compensation sheet of Table 3 was created.

ㆍ Discotic Liquid Coating Liquid (DA-1)

9.1 parts by mass of a discotic liquid crystal DLC-A represented by the following chemical formula

0.9 mass part of ethylene oxide modified trimethylol propane acrylate (V # 360, a brand name, Osaka Organic Chemical Co., Ltd.)

0.2 mass part of cellulose acetate butyrate (CAB551-0.2, a brand name, the product of Eastman Chemical)

Cellulose acetate butyrate (CAB531-1, trade name, manufactured by Eastman Chemical) 0.05 parts by mass

1.3 parts by mass of the fluorine compound (F-1) represented by the following chemical formula

Irugacure 907 (brand name, product of Chiba Corporation) 3.0 mass parts

Kayacure DETX (brand name, Nippon Kayaku Co., Ltd.) 0.1 parts by mass

Methyl ethyl ketone 29.6 parts by mass

The thickness of the optically anisotropic layer of each film was 1.6 micrometers, respectively.

Moreover, the following performance evaluation tests were done about each obtained optical compensation sheet. The results are shown in Table 5.

(Performance Evaluation Test of Optical Compensation Sheet)

(Adhesiveness)

Optical compensation sheets KS-1 and KSR-1 to KSR-3 described in Table 5 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 the assembly of the liquid crystal display device, and the glass plate for the liquid crystal cell. The adhesiveness was evaluated by peeling an optical compensation sheet from a glass plate in the vertical direction, and examining the part which the peeling remainder produced.

(Double-circle): No occurrence at all (at the level of ten people who cannot recognize one)

: Slightly occurs (10 people evaluate and recognize 1 to 3 people)

(Triangle | delta): A little generate | occur | produces (level recognized by 3 to 5 people by 10 people evaluation)

×: Strongly occurred (10 people rated and 6 or more recognized)

(Transmission light stain)

Each optical compensation sheet was sandwiched between two polarizing plates arranged at right angles of Nicole, and transmitted light stains were visually observed for sensory evaluation.

： It does not occur at all (level that ten people evaluate and one cannot recognize)

(Triangle | delta): A little generate | occur | produces (level recognized by 1 to 5 people by 10 people evaluation)

×: Many occurrences (10 people evaluate and recognize by 6 or more)

As can be seen from the results shown in Table 5 below, the optical compensation sheet KS-1 of the present invention was very good in that adhesiveness was sufficient and no transmitted light unevenness occurred.

(Production of Polarizing Film)

PVA having an average degree of polymerization of 4000 and a degree of saponification of 99.8 mol% was dissolved in water to obtain an aqueous solution of 4.0%.

The solution was bend-cast and dried using a tapered die, and the film was prepared such that the width before stretching was 110 mm, the thickness was 120 m at the left end, and 135 m at the right end.

The film was peeled off from the bend, stretched at a 45 ° direction in a dry state, and immersed in an aqueous solution of 0.5 g / L of iodine and 50 g / L of potassium iodide for 1 minute at 30 ° C., followed by 100 g / L of boric acid and 60 g of potassium iodide. It was immersed in 70 degreeC for 5 minutes in 70 degreeC, water-washed at 20 degreeC for 10 second by the water washing tank, and then dried at 80 degreeC for 5 minutes, and the iodine type polarizing film (HF-01) was obtained. The polarizing film had a width of 660 mm and a thickness of 20 µm on both the left and right sides.

(Production of polarizing plate)

Each of the optical compensation sheets KS-1 and KSR-1 to 1-3 was attached to one side of the polarizing film HF-01 from the surface of the cellulose acylate film CA-1 using a polyvinyl alcohol adhesive. . In addition, one side was saponified to a cellulose triacetate film (TD-80UF manufactured by Fujishashin Film Co., Ltd.) having a thickness of 80 µm in the same manner as in the saponification treatment with the alkaline solution of Example 12, and a polyvinyl alcohol-based adhesive was applied. To the opposite side of the polarizing film.

The transmission axis of a polarizing film and the slow axis of a cellulose acylate film (CA-1) were arrange | positioned so that it might become parallel. The transmission axis of the polarizing film and the slow axis of the cellulose triacetate film were arranged to be perpendicular to each other. In this way, polarizing plates HB-1 and HBR-1 to HBR-3 were produced.

(LCD)

A pair of polarizing plates formed on a liquid crystal display device (6E-A3, manufactured by Sharp Co., Ltd.) using a TN-type liquid crystal cell was removed, and the optical compensation sheet produced in Example 1 was produced instead of each polarizing plate produced above. It adhere | attached one by one to the observer side and the backlight side using an adhesive so that it might become a liquid crystal cell side. The transmission axis of an observer side polarizing plate and the transmission axis of a backlight side polarizing plate were arrange | positioned so that it might become O mode.

The following evaluation test was done about the obtained liquid crystal display device. The results are shown in Table 5.

(Stain evaluation of the drawing image)

About the liquid crystal display device produced in this way, the drawing spot at the time of black display (L1) was visually observed using the measuring device (EZ-Contrast 160D, ELDIM make).

： It does not occur at all (level that ten people evaluate and one cannot recognize)

(Triangle | delta): A little generate | occur | produces (level recognized by 1 to 5 people by 10 people evaluation)

×: Many occurrences (10 people evaluate and recognize by 6 or more)

(Contrast and Viewing Angle of Drawing Image)

White display voltage 2V and black display voltage 6V were applied to the liquid crystal cell of a liquid crystal display device, and the front contrast ratio was measured using the measuring device (EZ-Contrast 160D, ELDIM make). In addition, the viewing angle (angle range in which the contrast ratio is 10 or more) in the horizontal direction (orthogonal to the rubbing direction of the cell) was investigated.

Optical Compensation Sheet Support Film Alignment Film Adhesion Optical Compensation Sheet LCD Display Adhesion Transmitted light Smudge Viewing Angle (Left / Right) Contrast Example 12 KS-1 FS-1 ◎ ◎ 160 120 Comparative Example 12-1 KSR1-1 FSR1-1 × △ △ △ Comparative Example 12-2 KSR1-2 FSR1-2 × △ × ~ × Comparative Example 12-3 KSR1-3 FSR1-3 △ △ × ~ ×

As can be seen from the results shown in Table 5, the liquid crystal display device using the optical compensation sheet of the present invention, which uses the cellulose acylate film KS-1 as a transparent support, is clear and the brightness of the entire screen is not blurred. The drawing image which was a high image and was excellent in contrast and a viewing angle was obtained. That is, visibility was favorable. On the other hand, the thing which used the comparative films KSR-1 and KSR-3 was a problem for showing a stain | stain over the whole screen surface, and providing it to practical use.

From the above visual observation results, it was found that the use of the optical compensation sheet of the present invention had good optical characteristics, and the liquid crystal image device to which the optical compensation sheet was attached had excellent drawing property.

Example 13

(Production of Transparent Support)

(Adjustment of Particulate Dispersion (RL-2))

A mixture consisting of the following composition and zirconia beads having a bead diameter of 0.3 mm were introduced into a dino mill disperser, wet-dispersed, and dispersed to a volume average particle size of 65 nm. From the obtained dispersion, the beads were separated with a 200 mesh nylon cloth to prepare a fine particle dispersion (RL-2).

The dispersed particle diameter of the obtained dispersion was measured by a scanning electron microscope. Moreover, when the particle size distribution of the dispersion was measured (laser analysis, scattering particle diameter distribution measuring apparatus LA-920 manufactured by Horiba, Ltd.), particles having a particle size of 300 nm or more were 0%.

ㆍ Particulate dispersion (RL-2) composition

Hydrophobic silica (brand name "AEROSIL972" methyl group modified body, primary particle size 16nm: Nippon Aerosil Co., Ltd.) 2.20 parts by mass

2.00 parts by mass of cellulose triacetate having an acetylation degree of 59.9% (6-position substitution degree of 0.90)

0.22 parts by mass of monododecyl phosphate

(Particulate Dispersion Aid)

0.08 parts by mass of biphenyldiphenylphosphate

71.0 parts by mass of methyl acetate

6.2 parts by mass of methanol

Acetone 6.1 parts by mass

Ethanol 6.1 parts by mass

6.1 parts by mass of 1-butanol

(Adjustment of cellulose acylate solution (A-2))

Each component of the following composition was put into the mixing tank, and it stirred by heating, and prepared the cellulose acylate solution.

ㆍ Cellulose Acylate Solution (A-2) Composition

100 parts by mass of cellulose triacetate having an acetylation degree of 59.9% (6-position substitution degree of 0.90)

Triphenyl phosphate 7.9 parts by mass

3.9 parts by mass of biphenyldiphenylphosphate

UV agent represented by the following chemical formula: 1.0 parts by mass of UV-1

UV agent represented by the following chemical formula: 1.0 parts by mass of UV-2

290 parts by mass of methyl acetate

25 parts by mass of methanol

Acetone 25 parts by mass

25 parts by mass of ethanol

25 parts by mass of 1-butanol

4 mass parts of said cellulose triacetate, 16 mass parts of retardation regulators shown by following formula, 74.4 mass parts of methyl acetate, 6.4 mass parts of methanol, 6.4 mass parts of acetone, 6.4 mass parts of ethanol, and 6.4 mass parts of i-butanol, and heating, The mixture was stirred to prepare a retardation regulator solution (RE-2).

10.5 parts by mass of the fine particle dispersion was added to 464 parts of the cellulose acylate solution, and the mixture was sufficiently stirred. Then, 36 parts by mass of the retardation regulator solution was mixed and sufficiently stirred, followed by standing at room temperature (25 ° C.) for 3 hours to obtain a non-uniform gel solution. After cooling at -70 ° C for 6 hours, the dope was heated and stirred at 50 ° C and completely dissolved.

Next, the obtained dope was filtered with a filter paper (manufactured by Toyoji Co., Ltd., # 63) having an absolute filtration accuracy of 0.01 mm at 50 ° C., followed by further filter filtration and defoaming with a filter paper (FH025, manufactured by Paul Co., Ltd.) having an absolute filtration accuracy of 0.0025 mm. Dope was prepared.

And dope was cast using the rotating drum softener.

The drum was hard chromium plated and the surface was used with a diameter of 200 mm and a width of 2500 mm, with an arithmetic mean roughness Ra of 0.010 μm and a ten point average roughness Rz of 0.016 μm.

The casting method was carried out under the same conditions as the bend casting described in Example 12. After the film surface temperature on the drum surface became 40 degreeC, it dried for 1 minute and peeled off the film which 50 mass% of residual solvents, and the width direction of the film with 40 mass% of residual solvents by the drying air of 140 degreeC using a tenter in the width direction It extended | stretched 17% by and maintained at 130 degreeC for 30 second as it is after the extending | stretching width. Then, it dried for 20 minutes by 130 degreeC dry air, and produced the cellulose acylate film (CA-2) of 0.25 mass% of residual solvent quantity in the form of a roll of 60 micrometers in thickness, 1000 m in length, and 1.34 m in width.

The retardation value (Re) in wavelength 590nm of obtained cellulose acylate film (CA-2) was 29 nm, and the retardation value (Rth) in wavelength 590nm was 101 nm.

About the surface asperity shape of the cellulose acylate film (CA-2) of the obtained elongate roll, both surfaces of the drum surface side (outer surface) of the film and the opposite side (inner surface) of the drum surface were measured. The results are shown in Table 6.

Ra (μm) Rz (μm) Ry (μm) Sm (㎛) Inside 0.002 0.065 0.085 0.220 outside 0.003 0.074 0.092 0.250

As can be seen from the results shown in Table 6, the shape of the obtained film surface was constant in both shapes. Moreover, each ratio of (Ra) and (Ry) of an outer surface and an inner surface was less than 1.5, and the difference was small and favorable.

(Alkaline saponification treatment)

Next, after passing through a dielectric heating roll having a temperature of 60 ° C. and raising the temperature to a film surface temperature of 30 ° C., an alkali solution (S-2) having the following content was applied to the film inner surface side at a coating amount of 10 cc / m 2 using a rod coater. It was made to hold | maintain for 8 second under the steam type infrared heater manufactured by Noritake Co., Ltd. heated to 110 degreeC. Subsequently, 3 cc / m <2> of pure water was apply | coated similarly using the rod coater. The film temperature at this time was 40 degreeC. Subsequently, water washing with a fountain coater and water removal with an air knife were repeated three times, followed by drying for 5 seconds in a drying zone at 70 ° C.

The contact angle with water of the obtained film surface was 34 degree | times, and the surface shape of the surface was favorable without a spot.

ㆍ Alkaline Solution (S-2) Composition

5.0 parts by mass of potassium hydroxide

21.8 parts by mass of water

65.2 parts by mass of isopropanol

Ethylene Glycol 8.0 parts by mass

0.01 mass part of bubble remover Pluronic TR70 (made by Asahi Denka Co., Ltd.)

(Formation of alignment film)

Next, except for using the alignment film coating liquid (O-2) of the following composition, it carried out similarly to the formation of the alignment film in Example 12, and performed the rubbing process after apply | coating and drying the alignment film coating liquid.

ㆍ Oriental film coating liquid (O-2)

20 parts by mass of modified polyvinyl alcohol represented by the following chemical formula

0.06 parts by mass of carboxylic acid (A) represented by the following chemical formula

360 parts by mass of water

120 parts by mass of methanol

Glutalaldehyde 0.5 parts by mass

(Formation of optically anisotropic layer)

In the discotic liquid crystal coating liquid (DA-1) used in Example 1, 9.2 parts by mass of the liquid crystal DLC-B represented by the following chemical formula instead of the liquid crystal DLC-A and the fluorine compound (F-1) and the fluorine compound represented by the following formula ( F-2) Except using 1.4 parts by mass of the coating liquid DA-2, using the same coating liquid DA-2 as coating liquid DA-1, and using a wire bar coater of # 4, heated in a 125 ℃ high temperature bath for 3 minutes to discotic After aligning the liquid crystal, UV was irradiated with 500 mJ / cm 2 using a high pressure mercury lamp and allowed to cool to room temperature to prepare an optical compensation sheet KS-2.

The thickness of the optically anisotropic layer was 1.7 micrometers. The adhesiveness and planarity of the optical compensation sheet KS-2 prepared in the form of a long roll were evaluated in the same manner as in Example 12, and were the same as those in Example 1.

(Production of polarizing plate)

The optical compensation sheet KS-2 was stuck to the one side of the polarizing film (HF-01: Example 1 description) in the cellulose acylate film (CA-2) surface using the polyvinyl alcohol-type adhesive agent. A cellulose triacetate film (TD-80UF: manufactured by Fujishashin Film Co., Ltd.) having a thickness of 80 µm was saponified on one side by the same method as the saponification treatment with an alkali solution of Example 12, and a polyvinyl alcohol-based adhesive was applied. To the opposite side of the polarizing film.

The transmission axis of a polarizing film and the slow axis of a cellulose acylate film (CA-2) were arrange | positioned so that it might become parallel. The transmission axis of the polarizing film and the ground axis of the cellulose triacetate film were arranged to be perpendicular to each other. In this way, the polarizing plate (HB-2) was produced.

(Manufacture of Bend Orientation Liquid Crystal Cell)

A polyimide film was formed as an alignment film on a glass substrate provided with an ITO electrode, and a rubbing treatment was performed on the alignment film. The obtained two glass substrates were faced in the arrangement | positioning which a rubbing direction becomes parallel, and the cell gap was set to 6 micrometers. A liquid crystal compound (ZLI1132, manufactured by Merck) having a Δn (difference between refractive indices ne and no) of 0.1396 was injected to prepare a bend alignment liquid crystal cell. The size of the liquid crystal cell was 20 inches.

The produced bend alignment liquid crystal cell was sandwiched between and 2 sheets of the polarizing plates (HB-2) produced above were stuck. The optically anisotropic layer of the polarizing plate faced the cell substrate, and the rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing it were arranged so as to be antiparallel.

A rectangular wave voltage of 55 kV was applied to the liquid crystal cell. It was set as the normally white mode of white display 2V and black display 5V. The ratio of the transmittance (white display / black display) was used as the contrast ratio, and the viewing angle was measured in eight steps from the black display (L1) to the white display (L8) using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM).

As an evaluation measure of the viewing angle, the contrast ratio of the image in the field of view is maintained at 10 or more, and the value of the angle in the range in which the black tone inversion does not occur (that is, no inversion occurs between the black display L1 and the next level L2). Was used.

The result was 160 degrees and was favorable.

(Smudge evaluation on the liquid crystal display panel)

The display panel of the liquid crystal display device of Example 13 was adjusted in halftone of the whole surface, and the unevenness was evaluated. In Example 13, no stain was observed in any direction.

(Evaluation in TN Liquid Crystal Cell)

A pair of polarizing plates formed on a liquid crystal display device (AQUOS LC20C1S, manufactured by Sharp Co., Ltd.) using a TN type liquid crystal cell is removed, and the optical compensation sheet (KS-2) is used instead of the polarizing plate (HB-2). It adhere | attached one by one on the observer side and the backlight side using an adhesive so that it might become a liquid crystal cell side. The transmission axis of the observer side polarizing plate and the transmission axis of the backlight side polarizing plate were arranged to be in O mode.

About the produced liquid crystal display device, the measuring angle (EZ-Contrast 160D, ELDIM Co., Ltd. make) measured the viewing angle which becomes the minimum in an image plane in 8 steps from black display L1 to white display L8.

The result was more than 80 degrees and was favorable.

Example 14

(Production of cellulose acylate film)

(Preparation of cellulose acetate stock solution)

The cellulose acetate stock solution solution (one dope solution) of the composition shown in Table 7 was prepared. Melting melt | dissolved each component by putting a raw material into the mixing tank, stirring, heating.

Cellulose Acylate Stock Solution Composition Won dope liquid Ⅰ Won dope liquid Ⅱ Acetylation degree 60.7% (6-position substitution degree 0.90) cellulose triacetate triphenyl phosphate (plasticizer) biphenyl diphenyl phosphate (plasticizer) UV agent U-1 UV agent U-2 methyl acetate methanol acetate 100 parts by mass 7.8 parts by mass 3.9 parts by mass 1 part by mass 1 part by mass 290 parts by mass 25 parts by mass 25 parts by mass 100 parts by mass 2 parts by mass 1 parts by mass 1 parts by mass 1 parts by mass 320 parts by mass 30 parts by mass 30 parts by mass ethanol 25 parts by mass 30 parts by mass 1-butanol 12 parts by mass 12 parts by mass

(Preparation of retardation regulator solution (RE-3))

11.6 parts by mass of the retardation regulator represented by the following chemical formula, 82.4 parts by mass of methyl acetate, 7.1 parts by mass of methanol, 7.1 parts by mass of acetone, and 3.4 parts by mass of n-butanol were added to another mixing tank and stirred while heating to retardation regulator solution (RE- 3) was prepared.

(Preparation of cellulose acetate dope solution for inner layer and outer layer)

The composition shown in Table 8 was added to a mixing tank under stirring in the order of the retardation aid solution (RE-3) and the fine particle dispersion (RL-2) in the original dope liquid, stirred and mixed to form an inner layer and an outer layer of cellulose. Acetate dope liquid was prepared. Each addition amount of the retardation regulator and fine particle dispersion with respect to 100 mass parts of cellulose acetates is as showing in Table 6.

The obtained dope was filtered by the filter (The Toyoji Co., Ltd. make, # 63) of absolute filtration accuracy 0.01 mm, and the filter (made by Paul Corporation, FH025) of absolute filtration precision at 50 degreeC.

Dope prescription for each floor Inner layer dope liquid A Outer layer dope liquid A One dope liquid I one dope liquid II retardation regulator liquid fine particle dispersion (RL-2) 482 parts by mass 72 parts by mass 9 parts by mass 473 parts by mass 26 parts by mass 10.2 parts by mass

The filtered dope was arrange | positioned so that an inner layer dope might be inside, and an outer layer dope might be both outside using a three-layer covalent lead die, and it was middle layer flexible using the bend softener. The bend softener used the same thing as Example 1. Dope discharge amount was adjusted so that inner layer thickness was 48 micrometer and both outer layer thickness was 6 micrometer, and the conditions of casting and drying were the same as Example 12, the draw ratio using a tenter was transversely stretched to 16%, and the width after extending | stretching 130 It hold | maintained at 30 degreeC for 30 second, and produced the cellulose acylate film (CA-3) of the roll form of length 3000m and width 1.2m. Re was 14 nm and Rth was 80 nm.

(Characteristics of Cellulose Acylate Film)

Table 9 shows the results obtained by evaluating the obtainability of the obtained transparent support.

(Saponification Treatment of Cellulose Triacetate Film)

Apply 1.0 mole / liter of potassium hydroxide solution (solvent: isopropyl alcohol / propylene glycol / water = 75/13/12 mass%) directly to the inner surface side surface of the cellulose triacylate film (CA-3) # 6. After heating at 40 ℃ for 10 seconds, apply water to the coated surface as it is wet with # 1.6 bar immediately, and immediately spray 25cc of washing water 500cc / ㎡ from the nozzle, and blow off the washing water on the film surface with air knife. It carries out continuously and is made to dry by the warm air of 100 degreeC, and the surface-saponified cellulose triacylate film (FS-3) is produced.

The contact angle with water of the obtained film surface was 33 degree | times, and the surface shape of the surface was favorable without a spot.

(Formation of alignment film)

On the single side of the obtained transparent support, the alignment film coating liquid (O-3) of the following formulation was applied with a wire bar coater of # 14, and dried for 60 seconds with a warm air of 60 ° C and 160 seconds with a warm air of 90 ° C to form an alignment film. A rolled transparent support was produced. Next, the rubbing process was performed in the direction which becomes an angle with the slow-axis direction of the elongate roll-type cellulose acetate film in which the orientation film mentioned above was 45 degree.

ㆍ Oriental film coating solution (O-3) prescription

19 parts by mass of modified polyvinyl alcohol represented by the following chemical formula

0.075 parts by mass of carboxylic acid compound A-2 represented by the following chemical formula

360 parts by mass of water

120 parts by mass of methanol

1 part by mass of glutaraldehyde

(Formation of optically anisotropic layer)

The discotic liquid crystal coating liquid (DA-3) of the following prescription was prepared in the tank made from SUS.

ㆍ Optical anisotropic layer coating liquid (DA-3) composition

42 parts by mass of discotic liquid crystalline molecules (DLC-C) represented by the following chemical formula

Ethylene oxide modified trimethylol propane triacrylate (V # 360, Osaka Organic Chemical Co., Ltd.) 4 parts by mass

Cellulose acetate butyrate (CAB551-0.2, manufactured by Eastman Chemical Co., Ltd.) 0.92 parts by mass

Cellulose acetate butyrate (CAB551-0.2, manufactured by Eastman Chemical Co., Ltd.) 0.92 parts by mass

0.23 parts by mass of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.)

4.2 parts by mass of fluorine-containing compound (F-3) represented by the following chemical formula

1.40 parts by mass of a photopolymerization initiator (Irugacure 907, manufactured by Chiba Chemical Co., Ltd.)

Sensitizer (Kayacure DETX, manufactured by Nihon Kayaku Co., Ltd.) 0.45 parts by mass

111 parts by mass of methyl ethyl ketone

The coating liquid was applied to the wire bar of # 3 on the alignment film formed on the transparent support. This was heated for 2 minutes in a aging zone at 130 ° C. to orient the discotic liquid crystalline molecules. Next, UV irradiation was performed at 130 ° C. for 120 minutes using a 120 W / cm high-pressure mercury lamp to polymerize the discotic liquid crystalline molecules. Thereafter, the mixture was allowed to cool to room temperature. In this way, an optical compensation sheet (KS-3) having an optically anisotropic layer was produced.

When the performance of the obtained sheet was examined in the same manner as in Example 13, good performance equivalent to that of the optical compensation sheet of Example 13 was obtained.

(Production of Polarizing Film (HF-02))

The PVA film was immersed in an aqueous solution of 2.0 g / L iodine and 4.0 g / L potassium iodide at 25 ° C. for 240 seconds, again immersed in an aqueous solution of 10 g / L boric acid at 25 ° C. for 60 seconds, and introduced into a tenter stretching machine and stretched 5.3 times. Then, the width was kept constant and dried in an atmosphere at 80 ° C. while shrinking, and then wound off from the tenter. The moisture content of the PVA film before extending | stretching start was 31%, and the moisture content after drying was 1.5%.

The conveyance speed difference of the left and right tenter clips was less than 0.05%, and wrinkles and film deformation at the tenter exit were not observed.

It was 43.7% and the polarization degree 99.97% in 550 nm of the obtained polarizing film.

(Production of anti-reflection film)

The low-refractive-index layer coating liquid of the following prescription was stirred and prepared, and it filtered with the polypropylene filter of 1 micrometer of pore diameters, and then apply | coats with a bar coater on Fuji Tak (TD80U, Fujishashin Film Co., Ltd.), and 80 degreeC After drying 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, thereby preparing an antireflection film.

ㆍ Low Refractive Index Coating Composition

210 parts by mass of thermal 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 10-20nm, solid content concentration 30wt%, manufactured by Nissan Chemical Co., Ltd.)

200 parts by mass of methyl ethyl ketone

The anti-reflection film and the optical compensation sheet having the optically anisotropic layer prepared as described above were immersed in 1.5 mol / liter sodium hydroxide aqueous solution having a liquid temperature of 55 ° C. for 1 minute to saponify both sides, and then sufficiently washed with dilute sulfuric acid and water. After drying, a polyvinyl alcohol-based adhesive material was applied to each cellulose triacetate side with a thickness of about 30 μm, adhered to both sides of the polarizing film (HF-02), and dried at 80 ° C. to prepare a polarizing plate. .

(Production of bend alignment liquid crystal cell)

A polyimide film was formed as an alignment film on a glass substrate provided with an ITO electrode, and a rubbing treatment was performed on the alignment film. The obtained two glass substrates were faced in the arrangement which rubbing direction becomes parallel, and the cell gap was set to 6 micrometers. A bend alignment liquid crystal cell was prepared by injecting a liquid crystal compound (ZLI1132, manufactured by Merck) having a Δn (wavelength of 550 nm) of 0.1396 into the cell gap.

(Production of Bend Orientation Mode Transmissive Liquid Crystal Display)

Interposed the bend alignment liquid crystal cell thus prepared, and attaching an acrylic pressure-sensitive adhesive on the optically anisotropic layer of the optical compensation sheet of the polarizing plate (made of anti-reflection film, polarizing film, and optical compensation sheet) to the rubbing direction of the liquid crystal cell The rubbing direction of the optical compensatory sheet was attached so as to be antiparallel, thereby manufacturing a transmissive liquid crystal display device in a bend alignment mode.

White display voltage 2V and black display voltage 6V were applied to the liquid crystal cell of this liquid crystal display device, and the front contrast ratio was measured using the measuring device (EZ-Contrast 160D, ELDIM make). In addition, the viewing angle (angle range in which the contrast ratio is 10 or more) in the horizontal direction (orthogonal to the rubbing direction of the cell) was investigated.

The liquid crystal display of the present invention exhibits an excellent front contrast ratio of 200 and a viewing angle of 160 °, and has a good contrast and a wide viewing angle. Moreover, it was confirmed that it was a liquid crystal display device of the outstanding display quality without a blur and a foreign material on the surface.

(4th aspect, 5th aspect)

Example 15

The following composition was put into a mixing tank, stirred with heating, and each component was dissolved to prepare a cellulose acetate solution.

Cellulose Acetate Solution Composition

100 parts by mass of cellulose acetate having an acetylation degree of 60.8%

Triphenyl phosphate (plasticizer) 11.7 parts by mass

5.85 parts by mass of biphenyldiphenyl phosphate (plasticizer)

300 parts by mass of methylene chloride (first solvent)

54 parts by mass of methanol (second solvent)

11 parts by mass of 1-butanol (third solvent)

16 mass parts of following retardation increasing agents, 80 mass parts of methylene chlorides, and 20 mass parts of methanol were thrown into another mixing tank, and it stirred, heating, and prepared the retardation increasing agent solution.

25 mass parts of retardation increasing agent solutions were mixed with 474 mass parts of cellulose acetate solutions, and it fully stirred, and dope was prepared. The addition amount of the retardation increasing agent was 3.5 mass parts with respect to 100 mass parts of cellulose acetates.

The obtained dope was cast using a bend softener. The film with 15 mass% of residual solvents was transversely stretched by the tenter at 25 degreeC on the conditions of 130 degreeC, and the cellulose acetate film (thickness: 80 micrometers) was produced.

Furthermore, the produced cellulose acetate film was immersed in 1.5N potassium hydroxide solution (50 degreeC) for 2 minutes, and it neutralized with sulfuric acid. The cellulose acetate film was taken out of the solution, washed with pure water, and dried. The contact angle with respect to the water of the saponified cellulose acetate film surface was 40 degree | times.

About the produced cellulose acetate film (optical compensation sheet), the Re-retardation value and Rth retardation value in wavelength 550nm were measured using the ellipsometer (M-150, Nihon Bunco Co., Ltd. product). The results are shown in Table 10.

Example 16

Dope was prepared by mixing 56 parts by mass of the retardation increasing agent solution with 474 parts by mass of the cellulose acetate solution (using 7.8 parts by mass of the retardation increasing agent relative to 100 parts by mass of cellulose acetate) and changing the stretching ratio to 14%. A cellulose acetate film (optical compensation sheet) was produced in the same manner as in Example 15.

Furthermore, the produced cellulose acetate film was immersed in 1.5 N potassium hydroxide solution (40 degreeC) for 5 minutes, and it neutralized with sulfuric acid. The cellulose acetate film was taken out of the solution, washed with pure water, and dried. The contact angle with respect to the water of the saponified cellulose acetate film surface was 55 degree | times.

About the produced cellulose acetate film (optical compensation sheet), Re retardation value and Rth retardation value were measured like Example 15. The results are shown in Table 10.

Example 17

Dope was prepared by mixing 35 parts by mass of the retardation increasing agent solution with 474 parts by mass of the cellulose acetate solution (using 4.8 parts by mass of the retardation increasing agent relative to 100 parts by mass of cellulose acetate) and changing the stretching ratio to 28%. A cellulose acetate film was produced in the same manner as in Example 16.

Further, 1.0N potassium hydroxide solution (solvent: water / isopropyl alcohol / propylene glycol) was applied to 18 cc / m 2 on the produced cellulose acetate film and warmed to 40 ° C. so as not to dry completely. The alkaline liquid was removed with. The contact angle with respect to the water of the alkali-treated cellulose acetate film surface was 58 degreeC.

On the alkali-treated surface of this cellulose acetate film, the coating liquid of the following composition was apply | coated 28 ml / m <2> with the wire bar coater of # 16. It dried for 60 second with the warm air of 60 degreeC, and 150 second with the warm air of 90 degreeC again.

Next, the rubbing process was performed to the formed film | membrane in the slow axis (measured at wavelength 632.8 nm) and 45 degree direction of a cellulose acetate film.

ㆍ Layer film coating liquid composition

10.0 parts by mass of the following modified polyvinyl alcohol

371.0 parts by mass of water

119.0 parts by mass of methanol

Glutalaldehyde 0.5 parts by mass

(Formation of optically anisotropic layer)

41.01 g of the following disk type (liquid crystalline) compound, ethylene oxide modified trimethylolpropane triacrylate (V # 360, Osaka Organic Chemical Co., Ltd.) 4.06 g, cellulose acetate butyrate (CAB551-0.2, Eastman Chemical Co., Ltd.) on an alignment film 0.90 g, cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.) 0.23 g, photopolymerization initiator (Irugacure 907, manufactured by Chiba Chemical Co., Ltd.) 1.35 g, sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) Production) 0.45 g and a citric acid ester (a mixture of citric acid, mono citric acid, citric acid diethyl ester, and triethyl citrate) 0.45 g in 102 g of methyl ethyl ketone were coated with a wire bar of # 3.6. This was attached to a metal frame and heated in a thermostat at 130 ° C. for 2 minutes to orient the discoid compound. Next, UV irradiation was carried out at 100 ° C. for 1 minute using a 120 W / cm high-pressure mercury lamp to polymerize the discoid compound. Thereafter, the mixture was allowed to cool to room temperature. In this way, an optically anisotropic layer was formed.

About the produced cellulose acetate film (optical compensation sheet), Re retardation value and Rth retardation value were measured similarly to Example 1. The results are shown in Table 1.

[Comparative Example 5]

A cellulose acetate film (optical compensation sheet) was produced in the same manner as in Example 15 except that the cellulose acetate solution was used as a dope and was not subjected to the stretching treatment and the saponification treatment, and then the Re retardation value and the Rth retardation value were measured. The results are shown in Table 10.

Retardation synergist (mass part) Contact angle (degrees) Stretch ratio (%) Re (nm) Rth (nm) Example 15 Example 16 Example 17 Comparative Example 5 3.57.84.8 None 40405820 Not stretched 4050354 13024017548

Example 18

Iodine was adsorbed to the stretched polyvinyl alcohol film to prepare a polarizing film, and the cellulose acetate film prepared in Example 15 was attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. And a saponification process was carried out to the commercially available cellulose acetate film (Fuji Tak TD80UF, Fujishashin Film Co., Ltd. product), and it adhered to the opposite side of the polarizing film using the polyvinyl alcohol-type adhesive agent.

The contact angle with respect to water of the surface after saponification of the commercially available cellulose acetate film was 18 degrees.

The transmission axis of a polarizing film and the slow axis of the cellulose acetate film produced in Example 15 were arrange | positioned so that it might become parallel. The transmission axis of the polarizing film and the slow axis of a commercially available cellulose triacetate film were arranged so as to cross at right angles.

In this way, a polarizing plate was produced.

Example 19

A polarizing plate was produced in the same manner as in Example 18 except that the cellulose acetate film prepared in Example 16 was used.

Example 20

The optical compensation sheet produced in Example 17 was immersed in 1.5 N aqueous sodium hydroxide solution (50 ° C.) for 2 minutes, and then neutralized with sulfuric acid. The cellulose acetate film was taken out of the solution, washed with pure water, and dried. The contact angle with respect to the water of the saponified cellulose acetate film surface (surface on the side without a discoid compound layer) was 40 degree | times.

A polarizing plate was produced in the same manner as in Example 18 except for the above.

Example 21

A pair of polarizing plates and a pair of optical compensation sheets formed on a liquid crystal display device (VL-1530S, manufactured by Fujitsu Co., Ltd.) using a vertical alignment liquid crystal cell were removed, and the polarizing plates produced in Example 4 were instead used. And adhered one by one to the observer side and the backlight side using an adhesive so that the cellulose acetate film produced in Example 15 might become a liquid crystal cell side. Orthogonal Nicole arrangement was carried out so that the transmission axis of the observer side polarizing plate might be an up-down direction, and the transmission axis of a backlight side polarizing plate might be left-right direction.

About the produced liquid crystal display device, the viewing angle was measured in 8 steps from the black display L1 to the white display L8 using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). The results are shown in Table 11.

Example 22

A pair of polarizing plates and a pair of optical compensation sheets formed on a liquid crystal display device (VL-1530S, manufactured by Fujitsu Co., Ltd.) using a vertical alignment liquid crystal cell were removed, and the polarizing plates produced in Example 19 were used instead. And adhere | attached on the observer side 1 piece using an adhesive so that the cellulose acetate film produced in Example 16 may become a liquid crystal cell side. In addition, one commercially available polarizing plate (HLC2-5618HCS, manufactured by Sanlitz Co., Ltd.) was attached to the backlight side. Orthogonal Nicole arrangement was carried out so that the transmission axis of the observer side polarizing plate might be an up-down direction, and the transmission axis of a backlight side polarizing plate might be left-right direction.

About the produced liquid crystal display device, the viewing angle was measured in 8 steps from the black display L1 to the white display L8 using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). The results are shown in Table 11.

Comparative Example 6

Regarding the liquid crystal display device (VL-1530S manufactured by Fujitsu Co., Ltd.) using a vertically aligned liquid crystal cell, from a black display (L1) to a white display (L8) using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM) The viewing angle was measured in eight steps. The results are shown in Table 11.

LCD Display Viewing angle (contrast ratio is more than 10 and there is no black-level inversion) Transmission axis direction 45 ° from the transmission axis Example 21 Example 22 Comparative Example 6 80 ° 80 ° 80 ° 80 ° 80 ° 44 ° (Note) black-tone inversion: inversion between L1 and L2

Example 23

(Production of bend alignment liquid crystal cell)

A polyimide film was formed as an alignment film on a glass substrate provided with an ITO electrode, and a rubbing treatment was performed on the alignment film. The obtained two glass substrates were faced in the arrangement which rubbing direction becomes parallel, and the cell gap was set to 6 micrometers. A bend alignment liquid crystal cell was prepared by injecting a phosphate crystalline compound (ZLI1132, manufactured by Merck Co., Ltd.) with a Δn of 0.1396 in the cell gap.

Two polarizing plates produced in Example 20 were sandwiched between the produced bend alignment liquid crystal cell. The optically anisotropic layer of the polarizing plate faced the cell substrate, and the rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing it were arranged so as to be antiparallel. A rectangular wave voltage of 55 kV was applied to the liquid crystal cell. It was set as the normally white mode of white display 2V and black display 5V. The ratio of the transmittance (white display / black display) was used as the contrast ratio, and the viewing angle was measured in eight steps from the black display (L1) to the white display (L8) using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). The measured results are shown in Table 12.

LCD Display Viewing angle (°) (range of contrast ratio more than 10 and no black-level inversion) Prize Ha Right and left Example 23 80 80 80 Note) Black-level inversion: Inversion between L1 and L2

Example 24

The cellulose acetate produced in Example 15 by removing the pair of polarizing plates formed in the liquid crystal display device (6E-A3, manufactured by Sharp Co., Ltd.) using a TN type liquid crystal cell, and replacing the polarizing plate produced in Example 18 instead. It adhere | attached one by one on the observer side and the backlight side using an adhesive so that a film might become a liquid crystal cell side. The transmission axis of the observer side polarizing plate and the transmission axis of the backlight side polarizing plate were arranged to be orthogonal to each other.

About the produced liquid crystal display device, the viewing angle was measured in 8 steps from the black display L1 to the white display L8 using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). The results are shown in Table 13.

Comparative Example 7

About a liquid crystal display device (6E-A3, manufactured by Sharp Co., Ltd.) using a TN type liquid crystal cell, a black display (L1) to white display (L8) using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM) The viewing angle was measured in step 8. The results are shown in Table 13.

LCD Display Viewing angle (°) (range of contrast ratio more than 10 and no black-level inversion) Prize Ha Right and left Example 24 Comparative Example 7 1815 2325 7737 (Note) black-tone inversion: inversion between L1 and L2

In order to optically compensate the liquid crystal cell, an optical compensation sheet made of a cellulose acylate film or an optical compensation sheet made of a transparent support such as a cellulose acylate film can be used for the liquid crystal display device.

When the optical compensation sheet is used in the liquid crystal display device, the optical compensation sheet is generally fixed to the liquid crystal cell with an adhesive. Therefore, when the polymer film used for the optical compensation sheet is expanded or contracted, the resulting deformation is suppressed as a whole of the optical compensation sheet to change the optical properties of the polymer film.

According to the research of the present inventors, it has been found that the change of the optical characteristic occurs from two causes. One cause is that the optical properties of the optical compensation sheet change due to expansion or contraction of the polymer film due to the change of the moist heat conditions in the use environment of the liquid crystal display device. Another cause is that a temperature distribution occurs in the surface of the optical compensation sheet due to a heat source (for example, a backlight) in the liquid crystal display device, and the thermal deformation causes a change in optical characteristics.

Cellulose acylate is generally difficult to be fully acylated and has some hydroxyl groups. And it turns out that it is easy to be influenced by environmental conditions by hydroxyl group.

In order to eliminate light leakage, fluctuations in optical characteristics of the optical compensation sheet due to environmental conditions may be suppressed.

Variation in optical properties is related to the photoelastic coefficient, thickness, virtual deformation and elastic modulus of the optical compensation sheet. Therefore, light leakage is significantly reduced by lowering the photoelastic coefficient of the optical compensation sheet and making the thickness thin, and also by reducing the deformation caused by the environment and reducing the elastic modulus.

As a result of further studies by the present inventors, in order to achieve both a function as an optical compensation sheet (Re, preferably, further control of Rth) and industrial manufacturing ease, and to prevent the light leakage, the cellulose acylate film surface It was proved that what is necessary is just to adjust the speed of sound inside so that it may satisfy (v) and (v) mentioned above.

The sound velocity in a film plane can be measured easily with a commercially available apparatus (for example, Sonic test tester SST-2500 type, Nomura Shoji).

As described above, according to the present invention, the liquid crystal cell can be optically compensated without a problem by using an optical compensation sheet having a conventional thickness or less. In addition, by using the optical compensation sheet according to the present invention in the liquid crystal display device, it is possible to suppress the increase in the frame type transmittance.

In 1st and 2nd aspect of this invention, in order to suppress a frame-type transmittance rise, the thickness d of the cellulose acylate film used for an optical compensation sheet is adjusted to 10 micrometer <d <85micrometer. And the sound velocity in the inside of a cellulose acylate film surface is adjusted to satisfy the above-mentioned (iv) and (iv).

By making the thickness and sound velocity of a cellulose acylate film into the said range, the said problem can be solved without degrading the handleability of the optical compensation sheet in production of an optical compensation sheet or the production process of sticking it to a polarizing plate.

In addition, when the thickness of the optical compensation sheet is reduced, the thickness of the liquid crystal display device can be made thin, and the thickness of the liquid crystal display device can be met. The protective film of the polarizing plate generally consists of a cellulose acylate film. When the optical compensation sheet is used as one protective film of the polarizing plate, an optical compensation function can be added to the polarizing plate without increasing the number of components of the polarizing plate.

The polarizing plate using the optical compensation sheet and the optical compensation sheet as a protective film can be advantageously used in a twisted nematic (TN) type liquid crystal display device.

In addition, the present inventors have diligently studied to solve the above problems, and as a result, when the high-strength particles are added and mixed to the film constituting the support to increase the strength, the smoothness of the surface of the support may be impaired. We found that visibility decreased. Further, as a result of examining the relationship between the smoothness of the surface of the support and the visibility, it was found that even when the surface of the support satisfies specific conditions even when the particles were added and mixed to improve the strength of the support, the visibility was improved. Came to complete.

The optical compensation sheet of the third aspect of the present invention is thin and lightweight even in the size of a large screen, and has sufficient mechanical properties and excellent visibility. In addition, the optical compensation sheet of the present invention has a good productivity without variation in the viewing angle characteristic and without variation in the viewing angle magnification even when manufactured in a wide elongated roll form.

Moreover, the polarizing plate and liquid crystal display device of this invention are also thin and light, and are excellent in visibility without the dispersion | variation of a viewing angle enlargement characteristic.

The optical compensation sheet using the cellulose acetate film of this invention can be used as a protective film of a polarizing plate also in any aspect, and can add an optical compensation function to a polarizing plate, without increasing the number of components to a polarizing plate. Moreover, when the optical compensation sheets of 4th and 5th aspect are used as a protective film of a polarizing plate, since a cellulose acylate film saponifies and a contact angle with water is large, it is excellent in adhesiveness with a polarizing film, and also includes water washing of a polarizing film. Water falls well in the machining process to improve the yield in the machining process.

The liquid crystal cell provided with the polarizing plate of this invention is optically compensated, and is excellent in visibility, and has a wide viewing angle.

Claims (31)

An optical compensation sheet composed of a cellulose acylate film, wherein the cellulose acylate film, In-plane retardation value (Re) is 0nm≤Re <20nm, The thickness d is 10 탆 <d <85 탆, The average ((Vmin + Vmax) / 2) of the minimum value (Vmin) and the maximum value (Vmax) of the sound velocity measured in the film plane is 2.2 km / sec <(Vmin + Vmax) / 2 <2.5 km / sec, An optical compensation sheet, wherein the ratio of the maximum value (Vmax / Vmin) to the minimum value of the sound velocity measured in the plane of the film is 1.01 <Vmax / Vmin <1.12. An optical compensation sheet composed of a cellulose acylate film and an optically anisotropic layer formed of a liquid crystalline compound, wherein the cellulose acylate film is In-plane retardation value (Re) is 0nm≤Re <20nm, The thickness d is 10 탆 <d <85 탆, The average ((Vmin + Vmax) / 2) of the minimum value (Vmin) and the maximum value (Vmax) of the sound velocity measured in the film plane is 2.2 km / sec <(Vmin + Vmax) / 2 <2.5 km / sec, An optical compensation sheet, wherein the ratio of the maximum value (Vmax / Vmin) to the minimum value of the sound velocity measured in the plane of the film is 1.01 <Vmax / Vmin <1.12. The optical compensation sheet according to claim 1 or 2, wherein the cellulose acylate film contains an aromatic compound having two or more aromatic rings. 4. The optical compensatory sheet according to claim 3, wherein the aromatic compound has at least one 1,3,5-triazine ring. An optical compensation sheet formed by stacking an anti-corrosion film and an optically anisotropic layer in this order on a transparent support having a film thickness of at least 20 µm and 80 µm, including at least an average primary particle diameter of 80 nm or less. Arithmetic mean roughness Ra of surface irregularities based on JIS B0601-1994 on the surface of the alignment film of the transparent support is 0.0002 µm or more and 0.1 µm or less, 10-point average roughness Rz is 0.0002 µm or more and 0.3 µm or less Height Ry is 0.002 micrometer or more and 0.5 micrometer or less, The value of Re defined by Formula (I) and (II) of the transparent support is 2 nm or more and 200 nm or less, and the value of Rth is the range of 50 nm or more and 400 nm or less. (I) Re = (nx-ny) × d (II) Rth = {(nx + ny) / 2-nz} [Wherein nx is the refractive index in the slow axis direction in the plane of the transparent support; ny is the refractive index in the fast axis direction in the plane of the transparent support; nz is the refractive index in the thickness direction of the transparent support; and d is the transparent support. Is the thickness of.] 6. The arithmetic mean roughness Ra and the ten points according to claim 5, wherein an average spacing Sm of surface irregularities based on JIS B0601-1994 on the alignment film side surface of the transparent support is 0.001 µm or more and 5 µm or less. An optical compensation sheet, wherein the ratio (R / Rz) of the average roughness Rz is 0.1 or more and 1 or less. 6. The transparent support according to claim 5, wherein the transparent support is a long product having a length of 100 m or more and 5000 m or less and a width of 0.7 m or more and 2 m or less, a curl in the width direction of -10 / m to + 10 / m, and JIS K7128-2: An optical compensation sheet based on 1998 having a tear strength of 2 g or more. The optical compensation sheet according to claim 5, wherein the transparent support has an absolute value of an in-plane average of the slow axis angle of 0 degrees or more and 3 degrees or less, and a standard deviation of the slow axis angle of 0 degrees or more and 1.5 degrees or less. . The cellulose acylate film according to claim 5, wherein the transparent support comprises a cellulose acylate in the range of 55.0 to 62.5% of acetylation, the microparticles and a cellulose acylate film each containing at least one aromatic compound having two or more aromatic rings. Optical compensation sheet, characterized in that. The optical compensation sheet according to claim 9, wherein the aromatic compound has at least one 1,3,5-triazine ring. The said transparent support is a cellulose acylate film just manufactured by the solution casting | flow_spreading method which has a casting | flow_spread process, The metal support which casts the dope of the casting | flow_spreading process has the arithmetic mean roughness Ra of the surface. Is 0.001 µm or more and 0.015 µm or less, and the ten-point average roughness Rz of the surface thereof is 0.001 µm or more and 0.05 µm or less. 6. The arithmetic mean roughness Ra and the maximum height Ry of the surfaces of the transparent support body opposite to the alignment film side of the transparent support are 3 of the arithmetic mean roughness Ra and the maximum height Ry of the surface of the alignment film layer, respectively. Optical compensation sheet, characterized in that less than twice. The said transparent support body is a cellulose acylate film, The cellulose acylate film is a solution preparation process of preparing a cellulose acylate solution by melt | dissolving a cellulose acylate in the substantially non-chlorine solvent, The cellulose acylate solution It is a film manufactured by the film manufacturing process of film-forming a cellulose acylate film, and the extending process of extending | stretching a cellulose acylate film with the optical compensation sheet characterized by the above-mentioned. 15. The organic solvent of claim 13, wherein the substantially non-chlorine solvent comprises at least one organic solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and esters having 3 to 12 carbon atoms; It is a mixed solvent with alcohol, The optical compensation sheet characterized by the ratio of the alcohol in the whole solvent in the range of 2-40 mass%. The optical compensation sheet according to claim 5, wherein the transparent support is surface-treated with an alkaline solution containing at least a water-soluble organic solvent having a boiling point of 60 to 120 ° C and a surfactant and / or a compatibilizer. The optical compensatory sheet according to any one of claims 1, 2, 9, 11, and 13, wherein the cellulose acylate is cellulose acetate. The optical compensation sheet according to claim 5, wherein the optically anisotropic layer is made of a liquid crystalline compound. An optical compensation sheet comprising a cellulose acetate film having an acetylation degree of 59.0 to 61.5%, and having a saponified surface, and having a contact angle of water on the surface of 30 ° or more and 70 ° or less. It has an optically anisotropic layer made of a liquid crystalline compound on one side of the cellulose acetate film support having an acetylation degree of 59.0 to 61.5%, and the other side of the support is saponified, and the contact angle of water is 30 ° to 70 °. Optical compensation sheet, characterized in that. The optical compensation sheet according to claim 18 or 19, wherein the cellulose acetate film contains 0.01 to 20 parts by mass of an aromatic compound having two or more aromatic rings with respect to 100 parts by mass of cellulose acetate. 21. The optical compensation sheet of claim 20, wherein the aromatic compound has at least one 1,3,5-triazine ring. 19. The method according to claim 18, wherein the Re retardation value defined by the following formula (I) of the cellulose acetate film is 5 to 100 nm, and the Rth retardation value defined by the following formula (II) is 70 to 400 nm. Optical compensation sheet characterized by. Equation (I): Re = (nx-ny) × d Equation (II): Rth = {(nx + ny) / 2-nz} × d [Wherein nx is the refractive index in the slow axis direction in the film plane; ny is the refractive index in the fast axis direction in the film plane; nz is the refractive index in the thickness direction of the film; and d is the thickness (nm) of the film.] 20. The optical compensation sheet according to any one of claims 2, 17 and 19, wherein the liquid crystalline compound is a discotic liquid crystalline compound. A polarizing plate composed of a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films uses the optical compensation sheet according to any one of claims 1, 2 and 5. . A polarizing plate according to claim 24, wherein the transmission axis of the polarizing film and the slow axis of the transparent protective film are substantially vertical or parallel. A polarizing plate composed of a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films is the optical compensation sheet according to claim 18 or 19, and the optical compensation sheet is a saponification surface of the support on the polarizing film side. It is arrange | positioned so that it may become a polarizing plate. The polarizing plate according to claim 26, wherein the transmission axis of the polarizing film and the slow axis of the transparent protective film are substantially vertical or parallel. A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein the polarizing plate comprises a polarizing film and two transparent protective films disposed on both sides thereof, wherein two transparent protective films are disposed between the liquid crystal cell and the polarizing film. At least one used the optical compensation sheet in any one of Claims 1, 2, 5, 18, and 19, The liquid crystal display device characterized by the above-mentioned. The liquid crystal display device according to claim 28, wherein the liquid crystal cell is a liquid crystal cell of any one of a TN mode, a VA mode, an MVA mode, an n-ASM mode, and an OCB mode. In the method for producing a cellulose acylate film in which a cellulose acylate solution is cast on a metal substrate and is peeled off from the metal substrate and dried, the volatile acylate film after peeling is 100 to 160 ° C in a state of 45 to 70%. A method for producing a cellulose acylate film, which is dried for 10 to 1000 seconds by warm air. As a transparent support body is a cellulose acylate film, The manufacturing method of the optical compensation sheet of Claim 5 which manufactures the said transparent support body by film-forming the cellulose acylate film by the solution casting | flow_spreading method which has a casting process, The metal support which casts the dope of the said casting process has the arithmetic mean roughness Ra of the surface of 0.001 micrometer or more and 0.015 micrometer or less, and the 10 point average roughness Rz is 0.001 micrometer or more and 0.05 micrometer or less, It is characterized by the above-mentioned. Method for producing an optical compensation sheet.