JP2006265288A - Transparent film, method for producing transparent film, optical compensatory film, polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent film having small optical anisotropy and being substantially optically isotropic, having small change of optical performance by environmental change of temperature, humidity, etc., and suitable for liquid crystal display devices. <P>SOLUTION: In the transparent film, at least one coefficient of thermal expansion of coefficient (αMD) of thermal expansion in mechanical direction and coefficient (αTD) in the direction which is vertical to mechanical direction is 1.0×10<SP>-5</SP>to 10×10<SP>-5</SP>/°C and the coefficient of thermal expansion in mechanical direction is 0.4-1.0 times based on the coefficient of thermal expansion in the direction which is vertical to mechanical direction and retardation value of the film satisfy the formula (i): 0≤Re<SB>(590)</SB>≤20 and the formula (ii): ¾Rth<SB>(590)</SB>¾≤25 [wherein Re<SB>(λ)</SB>and Rth<SB>(λ)</SB>are each retardation value in in-plane direction and film thickness direction in wavelength λnm]. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transparent film, a method for producing a transparent film, an optical compensation film, a polarizing plate, and a liquid crystal display device.

A liquid crystal display (LCD) includes a liquid crystal cell and a polarizing plate. The polarizing plate has a protective film and a polarizing film, and is formed by, for example, dyeing and stretching a polarizing film made of polyvinyl alcohol with iodine and attaching protective films on both surfaces thereof. In the transmissive liquid crystal display device, the polarizing plates are disposed on both sides of the liquid crystal cell, and one or more optical compensation films may be disposed. In a reflective liquid crystal display device, a reflector, a liquid crystal cell, one or more optical compensation films, and a polarizing plate are arranged in this order.
The liquid crystal cell includes a liquid crystal molecule, two substrates for encapsulating the liquid crystal molecule, and an electrode layer for applying a voltage to the liquid crystal molecule. The liquid crystal cell performs ON and OFF display depending on the alignment state of liquid crystal molecules, and can be applied to both transmissive and reflective liquid crystal display devices. TN (Twisted Nematic), IPS (In-Plane Switching) Display modes such as OCB (Optically Compensatory Bend), VA (Vertically Aligned), and ECB (Electrically Controlled Birefringence) have been proposed.

  Among such LCDs, TN mode liquid crystal display devices (90-degree twisted nematic liquid crystal display devices) are suitable for applications that require high display quality. In the TN mode, nematic liquid crystal molecules having positive dielectric anisotropy are used and driven by a thin film transistor. Although this TN mode has excellent display characteristics when viewed from the front, the contrast is reduced when viewed from an oblique direction, or gradation inversion occurs in which the brightness is reversed in gradation display. There is a viewing angle characteristic that the characteristic is deteriorated, and this improvement is strongly desired.

  In order to solve such a problem, a liquid crystal display device using a so-called IPS mode (in-plane switching) in which a lateral electric field is applied to the liquid crystal, or a liquid crystal having a negative dielectric anisotropy is vertically aligned in the panel. A VA (vertical alignment) mode in which alignment is divided by protrusions and slit electrodes has been proposed and put into practical use. In recent years, these panels have been developed not only for monitors such as personal computers but also for TV applications, and accordingly, the brightness of the screen has been greatly improved. For this reason, slight light leakage in the diagonally oblique incidence direction during black display, which has not been considered as a problem in these operation modes, has become apparent as a cause of deterioration in display quality.

  As one means for improving the color tone and the viewing angle of black display, it is studied in the IPS mode to dispose an optical compensation material having birefringence characteristics between a liquid crystal layer and a polarizing plate. For example, by arranging a birefringent medium having an optical axis orthogonal to each other to compensate for the increase / decrease in retardation of the liquid crystal layer during tilting, a white display or a halftone display is diagonally arranged between the substrate and the polarizing plate. Has been disclosed (see Patent Document 1). Further, a method using an optical compensation film made of a styrene polymer having a negative intrinsic birefringence or a discotic liquid crystalline compound (see Patent Documents 2, 3, and 4) has been proposed.

  However, many of the proposed methods described above are methods that improve the viewing angle by canceling the birefringence anisotropy of the liquid crystal in the liquid crystal cell. There is a problem that light leakage based on a deviation from an orthogonal angle cannot be sufficiently solved. Even in a system that can compensate for this light leakage, it is very difficult to completely optically compensate the liquid crystal cell without any problem. This is because even if light leakage can be completely compensated at a certain wavelength, it cannot always be compensated at another wavelength. For example, even if the light loss is compensated at the green wavelength having the highest visibility, there is a problem in that light leakage occurs at a smaller wavelength blue or a larger wavelength red. In order to solve the above problem, Non-Patent Document 1 proposes to laminate two biaxial films. However, since two biaxial films are used in this method, there is a problem that the biaxial film is likely to be misaligned and screen unevenness is likely to occur. Further, light leakage at the time of black display is that the in-plane retardation Re is about 5 nm on the triacetylcellulose film conventionally used as a polarizing plate protective film between the liquid crystal cell and the polarizer, and the letter in the film thickness direction. It was also caused by the fact that the foundation Rth was about 50 nm. Therefore, it is desired to develop a transparent film having a small in-plane retardation Re and a retardation Rth in the film thickness direction and use it as a protective film for a polarizing plate.

  In recent years, the liquid crystal display device may be used in an environment where the temperature is increased by an internal backlight or in a high temperature and high humidity environment. The Re and Rth change, the optical compensation ability changes, and there is a problem that light leaks during black display or unevenness occurs in the image. Especially in such a case, the vertical and horizontal lengths of the display device may be different, and the members may have different physical properties depending on the vertical and horizontal directions. The trouble that the color changes was a problem. Therefore, there is a demand for means for producing a film with high productivity that can provide a liquid crystal display device with little change in the optical compensation function due to such an environment.

Japanese Patent Laid-Open No. 9-80424 Japanese Patent Laid-Open No. 10-54982 JP-A-11-202323 Japanese Patent Laid-Open No. 9-292522 Jpn. J. Appl. Phys. 41. (2002) 4553.

  The first problem of the present invention is to reduce the in-plane retardation Re and the retardation Rth in the film thickness direction so as to be almost zero, and to reduce a change in Re and Rth due to environmental changes such as temperature and humidity. Is to provide. Moreover, it is providing the manufacturing method which manufactures the transparent film which has said performance with sufficient productivity. The second problem of the present invention is to provide an optical compensation film and a polarizing plate using the above-mentioned transparent film, and cause light leakage and color change even when environmental changes such as temperature and humidity (particularly temperature) occur. It is to provide a superior liquid crystal display device.

The present invention is as follows.
(1) The thermal expansion coefficient (αMD) in the machine direction or the thermal expansion coefficient (αTD) in the direction perpendicular to the machine direction is 1.0 × 10 ⁻⁵ to 10 × 10 ⁻⁵ / ° C. Yes, the thermal expansion coefficient in the machine direction is 0.4 to 1.0 times the thermal expansion coefficient in the direction perpendicular to the machine direction, the in-plane retardation value Re, and the retardation in the film thickness direction A transparent film characterized in that the value Rth satisfies the following formulas (i) and (ii):
(I) 0 ≦ Re ₍₅₉₀₎ ≦ 20
(Ii) | Rth ₍₅₉₀₎ | ≦ 25
[In the formula, Re ₍ λ ₎ is an in-plane retardation value (unit: nm) at a wavelength λnm, and Rth ₍ λ ₎ is a retardation value (unit: nm) in the film thickness direction at a wavelength λnm. ]
(2) The transparent film according to (1), comprising a cellulose acylate.
(3) A polymer material is dissolved in a solvent to prepare a dope, the dope is cast on an endless support and continuously peeled off, and dried to produce a film (1) or (2) The transparent film manufacturing method according to claim 1, wherein a film forming speed is 50 to 300 m / min, and at least one of a tension applied in a machine direction and a tension applied in a direction perpendicular to the machine direction is adjusted. A method for producing a film.
(4) An optically anisotropic layer in which the in-plane retardation value Re and the retardation value Rth in the film thickness direction satisfy the following formula (iii) is provided on the transparent film described in (1) or (2). An optical compensation film characterized by comprising:
(Iii) Re ₍₅₉₀₎ = 0 to 200 (nm) and | Rth ₍₅₉₀₎ | = 0 to 300 (nm)
(5) The optical compensation film as described in (4), wherein the optically anisotropic layer contains a discotic liquid crystalline compound.
(6) The optical compensation film according to (4), wherein the optically anisotropic layer contains a rod-like liquid crystalline compound.
(7) The optical compensation film according to (4), wherein the optically anisotropic layer is a polymer film having birefringence.
(8) The transparent film according to (1) or (2) or the optical compensation film according to any one of (4) to (7) is used as a protective film for at least one polarizer. Polarizer.
(9) The transparent film according to (1) or (2), the optical compensation film according to any one of (4) to (7), or the polarizing plate according to (8) is used. Liquid crystal display device.
(10) The liquid crystal display device according to (9), wherein the liquid crystal display device is a VA or IPS type.

  According to the present invention, the in-plane retardation Re and the retardation Rth in the film thickness direction are reduced to almost zero, and a transparent film with little change in Re and Rth due to environmental changes such as temperature and humidity is produced. Can offer well. In addition, an optical compensation film and a polarizing plate using the above transparent film are provided, and an excellent liquid crystal display device that does not cause light leakage or color change even when environmental changes such as temperature and humidity (particularly temperature) occur can be provided. .

  The transparent film of the present invention can be preferably used as a transparent protective film for a polarizing plate which is a basic constituent member of a liquid crystal display device. The transparent film of this invention is demonstrated in detail below.

[Film retardation]
In the transparent film of the present invention, the in-plane retardation Re ₍₅₉₀₎ at a wavelength of 590 nm is 0 ≦ Re ₍₅₉₀₎ ≦ 20. Preferably, 0 ≦ Re ₍₅₉₀₎ ≦ 15, and more preferably 0 ≦ Re ₍₅₉₀₎ ≦ 10.
In the transparent film of the present invention, the retardation Rth ₍₅₉₀₎ in the film thickness direction at a wavelength of 590 nm is | Rth ₍₅₉₀₎ | ≦ 25. Preferably, | Rth ₍₅₉₀₎ | ≦ 23, and more preferably | Rth ₍₅₉₀₎ | ≦ 20.
Further, the retardation Re ₍₅₉₀₎ in the film plane and the retardation Rth ₍₅₉₀₎ in the film thickness direction can be controlled within the above desired ranges by controlling the polymer species and additives.

(Measurement of retardation)
In this specification, the in-plane retardation value Re of the transparent film is obtained by conditioning a sample 70 mm × 100 mm for 2 hours at 25 ° C. and 60% RH, and using an automatic birefringence meter (KOBRA21DH, Oji Scientific Co., Ltd.). The measurement wavelength is 590 nm, and the value is measured from a direction perpendicular to the film surface (hereinafter also referred to as a film normal direction).
The retardation value Rth in the film thickness direction of the transparent film is the normal direction of the film with the above-mentioned Re, slow axis or fast axis (determined by the automatic birefringence meter KOBRA 21ADH) as the tilt axis (rotation axis). From the direction inclined by + 40 ° with respect to the retardation value measured by making light of wavelength λ nm incident, and from the direction inclined by −40 ° with respect to the film normal direction with the slow axis as the inclination axis (rotation axis) A value calculated by an automatic birefringence meter KOBRA 21ADH based on the retardation values measured in three directions of the retardation values measured by making light having a wavelength λ nm incident.
In addition, nx, ny, and nz can be calculated by KOBRA 21ADH by inputting an assumed value of average refractive index of 1.48 and a film thickness d. (Where 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, and nz is the refractive index in the film thickness direction.)

[Coefficient of thermal expansion of film]
In order to prevent light leakage and optical density unevenness due to temperature and humidity changes in the liquid crystal display device, the thermal expansion coefficient of the film used as the protective film of the polarizing plate is reduced, and the ratio between the machine direction and the direction perpendicular to the machine direction is as much as possible. I found that it was effective to make it smaller.
In the transparent film of the present invention, the thermal expansion coefficient (αMD) in the machine direction (film transport direction in the film forming process) or the thermal expansion coefficient (αTD) in the direction perpendicular to the machine direction has a thermal expansion coefficient of 1. 0 × 10 ⁻⁵ to 10 × 10 ⁻⁵ / ° C., preferably 1.5 × 10 ^{−5 to} 8.0 × 10 ⁻⁵ / ° C., and 2.0 × 10 ^{−5 to} 7.0. More preferably, it is ^x10 < ^-5 > / ^degreeC . Examples of means for setting the thermal expansion coefficient of the film in the desired range include adjusting the type and amount of the polymer species and additives, adjusting the tension applied to the film during film production, and the like. .
Further, the thermal expansion coefficient in the machine direction is 0.4 to 1.0 times the thermal expansion coefficient in the direction perpendicular to the machine direction, preferably 0.5 to 1.0 times, and 0.6 to 1.0 times. Is more preferable. By appropriately adjusting the tension applied in the machine direction and the tension applied in the direction perpendicular to the machine direction during film production, the thermal expansion coefficient can be set to the desired range.

(Measurement method of thermal expansion coefficient)
A sample having a width of 3 mm and a length of 35 mm (measurement direction) is cut out from the film. The sample was conditioned for 3 hours or more in an environment of a temperature of 25 ° C. and a relative humidity of 60% RH. Next, the sample was measured using TMA (Thermal Mechanical Analyzer: TMA2940 type, manufactured by TA instruments) under the following conditions, and the thermal expansion coefficient was calculated as follows.
(Measurement condition)
Distance between chucks: 25mm
Temperature rising conditions: 30 ° C to 200 ° C (3 ° C / min)
Tension: 0.04N
The coefficient of thermal expansion is calculated from the rate of change of the inter-chuck dimension at 60 ° C. with respect to the temperature of the sample.
Measurements were made at 10 points at regular intervals along the width direction of the film, and the average value of the measured values was taken as the thermal expansion coefficient. A value obtained by dividing the difference between the maximum value and the minimum value among the measured values by the average value was defined as variation in the thermal expansion coefficient.

[Method for producing transparent film]
The transparent film of the present invention may be formed by thermally melting a thermoplastic polymer resin, or may be formed by solution film formation (solvent casting method) from a solution in which the polymer is uniformly dissolved, It is preferable to produce a film by a solvent cast method. Hereinafter, the solvent cast method will be described.
(Film preparation method by solvent casting method)
In order to produce a transparent film using the solvent casting method, first, a solution (dope) in which a polymer of a film raw material is dissolved in an appropriate organic solvent is prepared, and this dope is applied to an appropriate support (preferably a metal support). Cast on top. Thereafter, the solvent is dried, and when the film is gelled, it is peeled off from the support, and the solvent is sufficiently dried from the film to form a transparent film.

(Metal support)
The endlessly running metal support used for producing the transparent film of the present invention includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt (band) which is mirror-finished by surface polishing. ) Is used. In order to obtain a support having a smooth surface, a material with few impurities is sufficiently polished in a clean environment in which foreign substances are excluded as much as possible to obtain a mirror surface. For example, as described in JP-A No. 2000-84960, by setting the center line average roughness Ra of the support surface to 1 to 3 nm, the film surface roughness and film haze (haze value) do not increase. I have to. The smoothness of the film formed by these solution casting film forming methods becomes better as the number of foreign matters and irregularities on the surface of the support is smaller. The casting and drying methods in the solvent casting method are described in US Pat. No. 2,336,310, US Pat. No. 2,367,603, US Pat. No. 2,429,078, US Pat. British Patent 640731, British Patent 736892, JP-B 45-4554, JP-B 49-5614, JP-A 60-176834, JP-A 60-203430, JP-A 62 No. -11,035, each publication. The dope is preferably cast on a drum or band having a surface temperature of 30 ° C. or less, and particularly preferably a metal support temperature of −40 to 40 ° C. In addition, a method using a drum is preferable in that the film forming speed can be increased. In this case, the temperature of the metal support is preferably 0 to -40 ° C.

(Residual solvent amount when stripped)
In order to peel off the film, the amount of residual solvent in the film is preferably 60 to 300%. In addition, it represents with the following formula of the amount of residual solvents. The residual volatile matter weight is a value obtained by subtracting the film weight after the heat treatment from the film weight before the heat treatment when the film is heat treated at 120 ° C. for 2 hours.
Residual solvent amount = residual volatile matter weight / film weight after heat treatment × 100 (%)

(Tension applied during film transport)
In the drying process after peeling from the support, the film generally tends to shrink in the width direction (direction perpendicular to the machine direction) by evaporation of the solvent. In the production of the transparent film of the present invention, it is preferable to control so that the film is not strongly stretched in either the machine direction or the direction perpendicular thereto. Specifically, at the time of film transport in the machine direction, it is preferable that the strength of the tension applied from the film transport roll in the machine direction of the film is 1 to 50 kgf / m (9.8 to 490 N / m). On the other hand, it is preferable that the tension applied in the direction perpendicular to the machine direction is the same. In this case, a tenter system using a tenter clip for holding the film in the vertical direction and adjusting the tension can also be preferably used. For example, a method (tenter method) in which all or part of the drying process as shown in JP-A-62-46625 is dried while holding the width at both ends of the web with a clip in the width direction is preferably used. be able to.
Further, by adjusting the tension with a tenter, a target thermal expansion coefficient can be achieved even when the film forming speed is 50 to 300 m / min. In this case, for example, it is achieved by increasing the tension as the film forming speed is higher.

(Film forming speed)
The film forming speed is preferably 50 m / min or more from the viewpoint of production efficiency, more preferably 60 m / min, and even more preferably 70 m / min. Further, a speed higher than 300 m / min is not preferable because the manufacturing process becomes large and there are few merits.

[Material of transparent film]
As a material for forming the transparent film of the present invention, a polymer excellent in optical performance transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, and the like is preferable, and a range satisfying the above optical characteristics and thermal expansion coefficient. Any material may be used as long as it is. Examples include polycarbonate polymers, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, acrylic polymers such as polymethyl methacrylate, and styrene polymers such as polystyrene and acrylonitrile / styrene copolymer (AS resin). Polyolefins such as polyethylene and polypropylene, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers , Polyether ether ketone polymers, polyphenylene sulfide polymers, vinylidene chloride polymers, vinyl alcohol polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or polymers mixed with the above polymers Take an example. The transparent film of the present invention can also be formed as a cured layer of an ultraviolet-curable or thermosetting resin such as acrylic, urethane, acrylurethane, epoxy, or silicone.

  Moreover, as a material for forming the transparent film of the present invention, a thermoplastic norbornene resin can be preferably used. Examples of the thermoplastic norbornene-based resin include ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., and ARTON manufactured by JSR Corporation.

  Moreover, as a material which forms the transparent film of this invention, the cellulose polymer (henceforth a cellulose acylate) conventionally used as a transparent protective film of a polarizing plate can be used preferably. A representative example of cellulose acylate is triacetyl cellulose. Details of the cellulose acylate will be described below.

[Cellulose acylate raw cotton]
Cellulose acylate raw material cellulose used in the present invention includes cotton linter and wood pulp (hardwood pulp, softwood pulp) and the like, and any cellulose acylate obtained from any raw material cellulose can be used, optionally mixed. May be. Detailed descriptions of these raw material celluloses are, for example, Plastic Materials Course (17) Fibrous resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8) can be used, and the cellulose acylate film of the present invention is not particularly limited.

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

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

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

  As a result of intensive studies by the inventor of the present invention, among the acyl substituents substituted on the above-mentioned cellulose hydroxyl group, in the case of substantially consisting of at least two kinds of acetyl group / propionyl group / butanoyl group, the total substitution It was found that the optical anisotropy of the cellulose acylate film can be lowered when the degree is 2.50 to 3.00. The degree of acyl substitution is more preferably 2.60 to 3.00, and even more preferably 2.65 to 3.00.

[Degree of polymerization of cellulose acylate]
The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average polymerization degree, and in cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. . If the degree of polymerization is too high, the viscosity of the cellulose acylate dope solution becomes high, and film production becomes difficult due to casting. If the degree of polymerization is too low, the strength of the produced film will decrease. The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. This is described in detail in JP-A-9-95538.
Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and most preferably 1.0 to 1.6. preferable.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of the cellulose acylate of the present invention, its moisture content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass or less. It is a cellulose acylate having a rate. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In order to obtain the moisture content of the cellulose acylate in the present invention, it is necessary to dry, and the method is not particularly limited as long as the desired moisture content is obtained. These cellulose acylates of the present invention are described in detail on page 7 to page 12 of the raw material cotton and the synthesis method in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in.

  The cellulose acylate of the present invention can be used as a single group or a mixture of two or more different types of cellulose acylates as long as the substituent, substitution degree, polymerization degree, molecular weight distribution and the like are within the above-mentioned ranges.

[Additive to cellulose acylate]
In the cellulose acylate solution of the present invention, various additives (for example, compounds that reduce optical anisotropy, wavelength dispersion regulators, ultraviolet inhibitors, plasticizers, deterioration inhibitors) according to applications in each preparation step. , Fine particles, optical property modifiers, etc.) can be added and these are described below. Further, the addition may be performed at any time in the dope preparation process, but may be performed by adding an additive to the final preparation process of the dope preparation process.
It is preferable to contain at least one compound that reduces the optical anisotropy of the cellulose acylate film of the invention, particularly the retardation Rth in the film thickness direction, within the range satisfying the following formulas (I) and (II).
(I) (Rth (A) −Rth (0)) / A ≦ −1.0
(II) 0.01 ≦ A ≦ 30
The above formulas (I) and (II) are: (I) (Rth (A) −Rth (0)) / A ≦ −2.0
(II) 0.05 ≦ A ≦ 25
It is more desirable to be
(I) (Rth (A) −Rth (0)) / A ≦ −3.0
(II) 0.1 ≦ A ≦ 20
It is even more desirable.
Here, Rth (A) is Rth (nm) of a film containing A% of a compound that lowers Rth, Rth (0) is Rth (nm) of a film not containing a compound that lowers Rth, and A is a film raw polymer. It is the weight (%) of the compound when the weight of is 100.

[Structural characteristics of compounds that reduce the optical anisotropy of cellulose acylate films]
The compound that reduces the optical anisotropy of the cellulose acylate film will be described. As a result of intensive studies, the inventors of the present invention have sufficiently reduced the optical anisotropy by using a compound that suppresses the orientation of cellulose acylate in the film in the plane and in the film thickness direction. Zero and Rth were close to zero. For this purpose, it is advantageous that the compound that lowers the optical anisotropy is sufficiently compatible with cellulose acylate, and the compound itself does not have a rod-like structure or a planar structure. Specifically, when a plurality of planar functional groups such as aromatic groups are provided, a structure having these functional groups in a non-planar rather than the same plane is advantageous.

(Log P value)
In producing the cellulose acylate film of the present invention, octanol is among the compounds that reduce the optical anisotropy by inhibiting the cellulose acylate in the film from being oriented in the plane and in the film thickness direction as described above. -Compounds with a water partition coefficient (log P value) of 0 to 7 are preferred. A compound having a log P value of more than 7 is poor in compatibility with cellulose acylate, and tends to cause film turbidity or powder blowing. In addition, since a compound having a log P value smaller than 0 has high hydrophilicity, the water resistance of the cellulose acetate film may be deteriorated. A more preferable range of the logP value is 1 to 6, and a particularly preferable range is 1.5 to 5.
The octanol-water partition coefficient (log P value) can be measured by a flask immersion method described in JIS Japanese Industrial Standard Z7260-107 (2000). Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement. As a calculation method, Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987).), Viswanadhan's fragmentation method (J. Chem. Inf. Comput. Sci., 29, 163 (1989).) Broto's fragmentation method (Eur. J. Med. Chem.- Chim. Theor., 19, 71 (1984).) And the like are preferably used, but Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27 , 21 (1987). When the log P value of a certain compound varies depending on the measurement method or calculation method, it is preferable to determine whether or not the compound is within the scope of the present invention by the Crippen's fragmentation method.

[Physical properties of compounds that reduce optical anisotropy]
The compound that reduces optical anisotropy may or may not contain an aromatic group. The compound that reduces the optical anisotropy preferably has a molecular weight of 150 or more and 3000 or less, preferably 170 or more and 2000 or less, and particularly preferably 200 or more and 1000 or less. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.
The compound that reduces optical anisotropy is preferably a liquid at 25 ° C. or a solid having a melting point of 25 to 250 ° C., more preferably a liquid at 25 ° C. or a melting point of 25 to 200 ° C. It is a solid. Moreover, it is preferable that the compound which reduces optical anisotropy does not volatilize in the process of dope casting for cellulose acylate film production and drying.
The addition amount of the compound that decreases the optical anisotropy is preferably 0.01 to 30% by mass, more preferably 1 to 25% by mass, and more preferably 5 to 20% by mass of the cellulose acylate. Is particularly preferred.
The compound that decreases the optical anisotropy may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.
The timing for adding the compound for reducing the optical anisotropy may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

The compound that reduces the optical anisotropy is such that the average content of the compound in the portion from the surface on at least one side to 10% of the total film thickness is the average content of the compound in the central portion of the cellulose acylate film. 80-99%. The abundance of the compound of the present invention can be determined, for example, by measuring the amount of the compound at the surface and in the center by the method using an infrared absorption spectrum described in JP-A-8-57879.
Specific examples of the compound that lowers the optical anisotropy of the cellulose acylate film preferably used in the present invention include compounds represented by any one of the following general formulas (13), (18), and (19). However, the present invention is not limited to these compounds.

[In General Formula (13), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. However, R ¹ , R ² and R ³ have 10 or more carbon atoms. ]

[In General Formula (18), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. ]

[In the general formula (19), R ⁴ , R ⁵ and R ⁶ each independently represents an alkyl group or an aryl group. ]

The compound of the general formula (13) will be described.
In the general formula (13), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Further, the total number of carbon atoms of R ¹ , R ² and R ³ is particularly preferably 10 or more. R ¹ , R ² and R ³ may be substituted, and the substituent is preferably a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group and a sulfonamide group, and an alkyl group, an aryl group, an alkoxy group, A sulfone group and a sulfonamide group are particularly preferred. Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 (E.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclooctyl, nonyl, adamantyl, decyl, t-octyl, undecyl, Dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred. As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, triphenylphenyl) are particularly preferable. Preferred examples of the compound represented by the general formula (13) are shown below, but the present invention is not limited to these specific examples.

  Although the preferable example of a compound represented by General formula (18) or General formula (19) below is shown below, this invention is not limited to these specific examples. In the compound represented by the general formula (18) or the general formula (19), specific examples of the alkyl group and the aryl group are the same as those in the general formula (13).

In the formula, Pr ¹ represents an isopropyl group.

[Wavelength dispersion modifier]
A compound for reducing the wavelength dispersion of the cellulose acylate film (hereinafter also referred to as a wavelength dispersion adjusting agent) will be described. In order to improve the Rth wavelength dispersion of the cellulose acylate film of the present invention, a compound that reduces the Rth wavelength dispersion ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | represented by the following formula (III): Is preferably contained within a range satisfying the following formulas (IV) and (V).
(III) ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ |
(IV) (ΔRth (B) −ΔRth (0)) / B ≦ −2.0
(V) 0.01 ≦ B ≦ 30
The above formulas (IV) and (V) are: (IV) (ΔRth (B) −ΔRth (0)) / B ≦ −3.0
(V) 0.05 ≦ B ≦ 25
It is more desirable to be
(IV) (ΔRth (B) −ΔRth (0)) / B ≦ −4.0
(V) 0.1 ≦ B ≦ 20
It is even more desirable.
Here, ΔRth (B) is ΔRth (nm) of the film containing B mass% of the wavelength dispersion adjusting agent, ΔRth (0) is ΔRth (nm) of the film not containing the wavelength dispersion adjusting agent, and B is the film raw polymer. This is the mass (%) of the wavelength dispersion adjusting agent when the mass is 100.
The above-mentioned wavelength dispersion adjusting agent has at least a compound having absorption in the ultraviolet region of 200 to ₄₀₀ nm and reducing | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | The wavelength dispersion of Re and Rth of the cellulose acylate film was adjusted by including 0.01 to 30% by weight of one type, cellulose acylate solid content.

  In general, the Re and Rth values of the cellulose acylate film have a wavelength dispersion characteristic that the longer wavelength side is larger than the shorter wavelength side. Therefore, it is required to smooth the chromatic dispersion by increasing Re and Rth on the relatively short wavelength side. On the other hand, a compound having absorption in the ultraviolet region of 200 to 400 nm has a wavelength dispersion characteristic in which the absorbance on the short wavelength side is larger than that on the long wavelength side. If the compound itself is isotropically present inside the cellulose acylate film, it is assumed that the birefringence of the compound itself, and thus the wavelength dispersion of Re and Rth, is large on the short wavelength side as well as the wavelength dispersion of absorbance. .

  Therefore, as described above, by using the compound having absorption in the ultraviolet region of 200 to 400 nm and assuming that the wavelength dispersion of Re and Rth of the compound itself is large on the short wavelength side, the Re and Rth of the cellulose acylate film are used. Chromatic dispersion can be prepared. For this purpose, the compound for adjusting the wavelength dispersion is required to be sufficiently homogeneously compatible with the cellulose acylate. The absorption band range in the ultraviolet region of such a compound is preferably 200 to 400 nm, more preferably 220 to 395 nm, and even more preferably 240 to 390 nm.

In recent years, liquid crystal display devices such as televisions, notebook personal computers, and mobile portable terminals have been required to have excellent transmittance of optical members used in liquid crystal display devices in order to increase luminance with less power. In that respect, a cellulose acylate film is a compound having absorption in the ultraviolet region of 200 to ₄₀₀ nm and reducing | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | When it is added, it is required to have excellent spectral transmittance. In the cellulose acylate film of the present invention, the spectral transmittance at a wavelength of 380 nm is preferably 45% or more and 95% or less, and the spectral transmittance at a wavelength of 350 nm is preferably 10% or less.

  As described above, the wavelength dispersion adjusting agent preferably used in the present invention preferably has a molecular weight of 250 to 1000 from the viewpoint of volatility. More preferably, it is 260-800, More preferably, it is 270-800, Most preferably, it is 300-800. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.

  It is preferable that the wavelength dispersion adjusting agent does not volatilize during the dope casting and drying process for producing the cellulose acylate film.

(Compound addition amount)
The amount of the chromatic dispersion adjusting agent preferably used in the present invention is preferably 0.01 to 30% by weight, more preferably 0.1 to 20% by weight of cellulose acylate. 2 to 10% by weight is particularly preferred.

(Method of compound addition)
These wavelength dispersion adjusting agents may be used alone or in combination of two or more compounds at an arbitrary ratio.
Further, the timing of adding these wavelength dispersion adjusting agents may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  Specific examples of the wavelength dispersion adjusting agent preferably used in the present invention include, for example, benzotriazole compounds, benzophenone compounds, cyano group-containing compounds, oxybenzophenone compounds, salicylic acid ester compounds, nickel complex compounds, and the like. However, the present invention is not limited to these compounds.

  As the benzotriazole-based compound, those represented by the general formula (101) are preferably used as the wavelength dispersion adjusting agent of the present invention.

Formula (101) Q ¹ -Q ² -OH

(In the formula, Q ¹ represents a nitrogen-containing aromatic heterocyclic group, and Q ² represents an aromatic cyclic group.)

Q ¹ represents a nitrogen-containing aromatic heterocyclic group, preferably a 5- to 7-membered nitrogen-containing aromatic heterocyclic group, more preferably a 5- to 6-membered nitrogen-containing aromatic heterocyclic group, Imidazole, pyrazole, triazole, tetrazole, thiazole, oxazole, selenazole, benzotriazole, benzothiazole, benzoxazole, benzoselenazole, thiadiazole, oxadiazole, naphthothiazole, naphthoxazole, azabenzimidazole, purine, pyridine, pyrazine, Examples of the ring group include pyrimidine, pyridazine, triazine, triazaindene, and tetrazaindene, and more preferably a 5-membered nitrogen-containing aromatic heterocycle or a triazine ring, specifically, imidazole, pyrazole, Triazole Each ring such as tetrazole, thiazole, oxazole, benzotriazole, benzothiazole, benzoxazole, thiadiazole, oxadiazole, 1,3,5-triazine is preferable, and benzotriazole ring or 1,3,5-triazine is particularly preferable. It is a ring.
The nitrogen-containing aromatic heterocycle represented by Q ¹ may further have a substituent, and the substituent T described below can be applied as the substituent. In addition, when there are a plurality of substituents, each may be condensed to form a ring.

The aromatic ring represented by Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, benzene ring, naphthalene ring etc.), more preferably 6 carbon atoms. An aromatic hydrocarbon ring having 20 to 20 carbon atoms, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.), More preferably a benzene ring.
The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. The aromatic hetero ring is preferably a pyridine ring, a triazine ring or a quinoline ring.

The aromatic ring group represented by Q ² is preferably an aromatic hydrocarbon ring group, more preferably a naphthalene ring group or a benzene ring group, and particularly preferably a benzene ring group. Q ² may further have a substituent, and the substituent T described later is preferable.

  Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl. , N-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, especially Preferably it is C2-C8, for example, each group, such as vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably C2-C20, more preferably C2-C2). 12, particularly preferably 2 to 8 carbon atoms, for example, groups such as propargyl and 3-pentynyl), aryl groups (preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl, and the like. A substituted amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, and particularly preferably 0 to 6 carbon atoms; for example, amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc. Group), an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, and examples thereof include methoxy, ethoxy and butoxy groups. An aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms). Ruoxy and 2-naphthyloxy groups), acyl groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms such as acetyl, Benzoyl, formyl, pivaloyl, etc.), alkoxycarbonyl groups (preferably having 2-20 carbon atoms, more preferably 2-16 carbon atoms, particularly preferably 2-12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc. And aryloxycarbonyl groups (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, and particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl group). An acyloxy group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, in particular Preferably it is C2-C10, for example, an acetoxy period, a benzoyloxy group etc. are mentioned. ),

An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include an acetylamino group and a benzoylamino group), an alkoxycarbonylamino group. (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino group), aryloxycarbonylamino group (preferably carbon 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as a phenyloxycarbonylamino group), a sulfonylamino group (preferably 1 to 20 carbon atoms, More preferably, it has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. And groups such as amino and benzenesulfonylamino), sulfamoyl groups (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methyl And each group such as sulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to carbon atoms). 12 and examples thereof include carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl and the like.

An alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio groups), an arylthio group (preferably having a carbon number) 6 to 20, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and the like, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 carbon atom). To 16, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl groups (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably carbon numbers). 1 to 12, for example, methanesulfinyl group, benzenesulfinyl group, etc.), ureido group (preferably having 1 carbon atom) 20, More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, each group, such as a ureido, methylureido, a phenylureido, etc.), phosphoric acid amide group (preferably C1) -20, more preferably 1-16 carbon atoms, particularly preferably 1-12 carbon atoms, and examples thereof include diethylphosphoric acid amide and phenylphosphoric acid amide groups), hydroxy groups, mercapto groups, halogen atoms (For example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having a carbon number of 1 to 30 and more preferably 1 to 12. Examples of the hetero atom include a nitrogen atom, an oxygen atom, and a sulfur atom, specifically, And each group such as imidazolyl, pyridyl, quinolyl, furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 3 carbon atoms). 30 and particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group).
These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

As the general formula (101), a compound represented by the following general formula (101-A) is preferable.
General formula (101-A)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a substituent)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represent a hydrogen atom or a substituent, and the substituent T described above can be applied as the substituent. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.
R ¹ and R ³ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably an alkyl group having 1 to 12 carbon atoms (preferably 4 to 12 carbon atoms).

R ² and R ⁴ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably Is a hydrogen atom.

R ⁵ and R ⁸ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably It is a hydrogen atom.

R ⁶ and R ⁷ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and a halogen atom, and particularly preferably a hydrogen atom and a chlorine atom.

More preferable as the general formula (101) is a compound represented by the following general formula (101-B).
General formula (101-B)

(In formula, R < ¹ >, R < ³ >, R < ⁶ > and R < ⁷ > are synonymous with those in general formula (101-A), and their preferred ranges are also the same.)

  Specific examples of the compound represented by formula (101) are listed below, but the present invention is not limited to the following specific examples.

  Among the benzotriazole compounds exemplified in the above examples, when the cellulose acylate film of the present invention was produced without including those having a molecular weight of 320 or less, it was confirmed that it was advantageous in terms of retention.

In addition, as the benzophenone compound which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (102) are preferably used.
Formula (102)

(In the formula, Q ¹ and Q ² each independently represent an aromatic ring. X represents NR (R represents a hydrogen atom or a substituent), an oxygen atom or a sulfur atom.)

The aromatic ring represented by Q ¹ and Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring represented by Q ¹ and Q ² is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring, a naphthalene ring, etc.). More preferably an aromatic hydrocarbon ring having 6 to 20 carbon atoms, still more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.) More preferably, it is a benzene ring.
The aromatic heterocyclic group represented by Q ¹ and Q ² is preferably an aromatic heterocyclic group containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, Examples include quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzothiazole, benzotriazole, and tetrazaindene. As the aromatic hetero ring, a pyridine ring, a triazine ring and a quinoline ring are preferable.
The aromatic ring group represented by Q ¹ and Q ² is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, still more preferably a substituted or unsubstituted benzene ring. It is.
Q ¹ and Q ² may further have a substituent, and the substituent T is preferable, but the substituent does not contain a carboxylic acid group, a sulfonic acid group, or a quaternary ammonium group. Further, if possible, substituents may be linked to form a ring structure.

  X represents NR (R represents a hydrogen atom or a substituent. Substituent T described later can be applied as the substituent), an oxygen atom or a sulfur atom, and X is preferably NR (R is preferably an acyl group) A sulfonyl group, and these substituents may be further substituted.) Or an oxygen atom, particularly preferably an oxygen atom.

  The substituent T is synonymous with that of the general formula (101).

As the general formula (102), a compound represented by the following general formula (102-A) is preferable.
Formula (102-A)

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represents a hydrogen atom or a substituent.)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or a substituent, and the above-mentioned substituent T is applied as the substituent. it can. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁸ and R ⁹ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, aryl An oxy group, a hydroxy group and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, still more preferably a hydrogen atom and a carbon 1-12 alkyl group. Particularly preferred are a hydrogen atom and a methyl group, and most preferred is a hydrogen atom.

R ² is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or one carbon atom. An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, and more preferably an alkoxy group having 1-20 carbon atoms. And particularly preferably an alkoxy group having 1 to 12 carbon atoms.

R ⁷ is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or one carbon atom. An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom, having 1-20 carbon atoms. An alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably a methyl group), particularly preferably a methyl group or a hydrogen atom.

More preferable as the general formula (102) is a compound represented by the following general formula (102-B).
General formula (102-B)

(Wherein R ¹⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group.)

R ¹⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. Applicable.
R ¹⁰ is preferably a substituted or unsubstituted alkyl group, more preferably a substituted or unsubstituted alkyl group having 5 to 20 carbon atoms, and still more preferably a substituted or unsubstituted alkyl group having 5 to 12 carbon atoms. (Including n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substitution of 6 to 12 carbon atoms or An unsubstituted alkyl group (2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group).

The compound represented by the general formula (102) can be synthesized by a known method described in JP-A-11-12219.
Specific examples of the compound represented by the general formula (102) are given below, but the present invention is not limited to the following specific examples.

As the compound containing a cyano group, which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (103) are preferably used.
General formula (103)

(In the formula, Q ¹ and Q ² each independently represents an aromatic ring. X ¹ and X ² represent a hydrogen atom or a substituent, and at least one of them represents a cyano group.)
The aromatic ring represented by Q ¹ and Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

  The aromatic hydrocarbon ring is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, benzene ring, naphthalene ring etc.), more preferably 6 carbon atoms. An aromatic hydrocarbon ring having 20 to 20 carbon atoms, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.), More preferably a benzene ring.

  The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. As the aromatic hetero ring, a pyridine ring, a triazine ring and a quinoline ring are preferable.

The aromatic ring represented by Q ¹ and Q ² is preferably an aromatic hydrocarbon ring, and more preferably a benzene ring.
Q ¹ and Q ² may further have a substituent, and the substituent T is preferred. The substituent T is synonymous with that of the general formula (101).

X ¹ and X ² each represent a hydrogen atom or a substituent, and at least one of them represents a cyano group. The substituent T described above can be applied to the substituents represented by X ¹ and X ² . The substituents represented by X ¹ and X ² may be further substituted with other substituents, and X ¹ and X ² may be condensed to form a ring structure.

X ¹ and X ² are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle, and more preferably a cyano group, a carbonyl group, a sulfonyl group, An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, 6 carbon atoms). ~ 12 aryl groups and combinations thereof.

Preferred as the general formula (103) is a compound represented by the following general formula (103-A).
General formula (103-A)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a substituent. X ¹ and X ² Are the same as those in formula (103), and the preferred range is also the same.)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a substituent. Is applicable. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, An alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, still more preferably a hydrogen atom and carbon 1-12. An alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ³ and R ⁸ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, halogen atoms, more preferably hydrogen atoms. , An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and a carbon number. An alkyl group having 1 to 12 carbon atoms and an alkoxy group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom.

More preferable as the general formula (103) is a compound represented by the following general formula (103-B).
General formula (103-B)

(Wherein R ³ and R ⁸ have the same meanings as those in formula (103-A), and preferred ranges are also the same. X ³ represents a hydrogen atom or a substituent.)

X ³ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with another substituent. X ³ is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group or an aromatic heterocyclic ring, more preferably a cyano group, a carbonyl group, a sulfonyl group or an aromatic heterocyclic ring. More preferably a cyano group or a carbonyl group, particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (where R is an alkyl group having 1 to 20 carbon atoms, aryl having 6 to 12 carbon atoms). Group and a combination thereof).

As the general formula (103), a compound represented by the general formula (103-C) is more preferable.
General formula (103-C)

(Wherein R ³ and R ⁸ have the same meanings as those in formula (103-A), and the preferred range is also the same. R ²¹ represents an alkyl group having 1 to 20 carbon atoms.)

R ²¹ is preferably an alkyl group having 2 to 12 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms, and still more preferably 6 carbon atoms when both R ³ and R ⁸ are hydrogen. To 12 alkyl groups, particularly preferably n-octyl group, tert-octyl group, 2-ethylhexyl group, n-decyl group, n-dodecyl group, most preferably 2-ethylhexyl. It is a group.

When R ³ and R ⁸ are preferably other than hydrogen as R ²¹ , the compound represented by the general formula (103-C) has a molecular weight of 300 or more and an alkyl group having 20 or less carbon atoms. preferable.

  The compound represented by the general formula (103) can be synthesized by the method described in Journal of American Chemical Society 63, 3452 (1941).

  Specific examples of the compound represented by the general formula (103) are given below, but the present invention is not limited to the following specific examples.

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the cellulose acylate film of the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable from the viewpoint of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

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

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

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

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

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

[Plasticizer, degradation inhibitor, release agent]
In addition to the above-mentioned compound that optically reduces anisotropy and the wavelength dispersion adjusting agent, the cellulose acylate film of the present invention has various additives (for example, a plasticizer, an ultraviolet ray, etc.) in each preparation step. Inhibitors, degradation inhibitors, release agents, infrared absorbers, etc.), which may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and similarly, mixing of a plasticizer is described in, for example, Japanese Patent Application Laid-Open No. 2001-151901. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the dope preparation step, but may be added by adding an additive to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a cellulose acylate film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For example, although it describes in Unexamined-Japanese-Patent No. 2001-151902 etc., these are techniques conventionally known. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.

[Rate of compound addition]
In the cellulose acylate film of the present invention, the total amount of compounds having a molecular weight of 3000 or less is preferably 5 to 45% based on the weight of the cellulose acylate. More preferably, it is 10 to 40%, and even more preferably 15 to 30%. As described above, these compounds include compounds that reduce optical anisotropy, wavelength dispersion regulators, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, etc. Is preferably 3000 or less, more preferably 2000 or less, and even more preferably 1000 or less. When the total amount of these compounds is 5% or less, the properties of cellulose acylate alone are likely to be obtained, and there are problems such as that the optical performance and physical strength are likely to vary with changes in temperature and humidity. Moreover, when the total amount of these compounds is 45% or more, problems such as exceeding the limit of compatibility of the compounds in the cellulose acylate film and depositing on the film surface and causing the film to become cloudy (crying out of the film) occur. It becomes easy.

[Organic solvent for cellulose acylate solution]
In the present invention, it is preferable to produce a cellulose acylate film by a solvent cast method, and the film is produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent. The organic solvent preferably used as the main solvent of the present invention is preferably a solvent selected from esters, ketones, ethers having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 7 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  As described above, chlorine-based halogenated hydrocarbons may be used as the main solvent for the cellulose acylate film of the present invention, and as described in JIII Journal of Technical Disclosure 2001-1745 (pages 12-16), A non-chlorinated solvent may be used as the main solvent, and is not particularly limited to the cellulose acylate film of the present invention.

  In addition, the solvent for the cellulose acylate solution and the film of the present invention is disclosed in the following patents, including its dissolution method, and is a preferred embodiment. They are, for example, JP 2000-95876, JP 12-95877, JP 10-324774, JP 8-152514, JP 10-330538, JP 9-95538, JP 9-95557, JP 10-10. -235664, JP-A-12-63534, JP-A-11-21379, JP-A-10-182853, JP-A-10-278056, JP-A-10-279702, JP-A-10-323853, JP-A-10-237186, JP-A-11-60807. JP-A-11-152342, JP-A-11-292988, JP-A-11-60752, JP-A-11-60752, and the like. According to these patents, not only the preferred solvent for the cellulose acylate of the present invention but also the physical properties of the solution and the coexisting substances to be coexisted are described, which is also a preferred embodiment in the present invention.

[Manufacturing process of cellulose acylate film]
[Dissolution process]
The method for dissolving the cellulose acylate solution (dope) of the present invention is not particularly limited, and it may be performed at room temperature or further by a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding the preparation of the cellulose acylate solution in the present invention, and further the steps of solution concentration and filtration associated with the dissolution step, the Technical Report of the Japan Society of Invention (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention) The manufacturing process described in detail on pages 22 to 25 is preferably used.

(Transparency of dope solution)
The dope transparency of the cellulose acylate solution of the present invention is preferably 85% or more. More preferably, it is 88% or more, and more preferably 90% or more. In the present invention, it was confirmed that various additives were sufficiently dissolved in the cellulose acylate dope solution. As a specific method for calculating the dope transparency, the dope solution was poured into a 1 cm square glass cell, and the absorbance at 550 nm was measured with a spectrophotometer (UV-3150, Shimadzu Corporation). Only the solvent was measured in advance as a blank, and the transparency of the cellulose acylate solution was calculated from the ratio with the absorbance of the blank.

[Casting, drying, winding process]
Next, a method for producing a film using the cellulose acylate solution of the present invention will be described. As a method and equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is fed from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations. The dry-dried dope film (also referred to as a web) is peeled off from the metal support at the peeling point which is uniformly cast on the metal support and the metal support has almost gone around. The both ends of the obtained web are sandwiched between clips, transported by a tenter while holding the width and dried, and then the obtained film is mechanically transported by a roll group of a drying device, dried, and then rolled by a winder Wind up to a predetermined length. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film or the silver halide photographic light-sensitive material which is an optical member for electronic display, which is the main use of the cellulose acylate film of the present invention, a solution casting film forming apparatus In addition, a coating apparatus is often added for surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, and a protective layer. These are described in detail on pages 25-30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society for Invention). Including), metal support, drying, peeling and the like, and can be preferably used in the present invention.
Moreover, 10-120 micrometers is preferable, as for the thickness of a cellulose acylate film, 20-100 micrometers is more preferable, and 30-90 micrometers is more preferable.

[Film characteristics]
(Chromatic dispersion of Re and Rth)
The transparent film of the present invention preferably has | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35. More preferably, | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 5 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 25, and | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 3 And | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 15 is particularly desirable.
As a specific measurement method, the sample was conditioned at 25 ° C. and 60% RH for 2 hours, and light with a wavelength of 780 nm to 380 nm was incident in the normal direction of the film on an ellipsometer M-150 (manufactured by JASCO Corporation). Thus, Re at each wavelength was determined, and the wavelength dispersion of Re was measured. Further, the wavelength dispersion of Rth was measured by introducing light having a wavelength of 780 to 380 nm from the direction inclined by + 40 ° with respect to the normal direction of the film with the slow axis in the plane as the tilt axis. The value and the retardation value measured by making light with a wavelength of 780 to 380 nm incident from a direction inclined by −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis were measured in a total of three directions. Based on the retardation value, it was calculated by inputting the assumed average refractive index of 1.48 and the film thickness.

(Glass glass transition temperature Tg)
The glass transition temperature Tg of the transparent film of the present invention is 80 to 165 ° C. From the viewpoint of heat resistance, Tg is more preferably 100 to 160 ° C, and particularly preferably 110 to 150 ° C. The glass transition temperature Tg is measured with a differential scanning calorimeter (DSC2910, T.A. Instruments) for 10 mg of the transparent film sample of the present invention from room temperature to 200 ° C. at a heating / cooling rate of 5 ° C./min. The glass transition temperature Tg was calculated.

(Haze of film)
The haze of the transparent film of the present invention is preferably 0.01 to 2.0%. More preferably, it is 0.05 to 1.5%, and more preferably 0.1 to 1.0%. As an optical film, the transparency of the film is important. The haze was measured by measuring a transparent film sample 40 mm × 80 mm of the present invention at 25 ° C. and 60% RH with a haze meter (HGM-2DP, Suga Test Instruments) according to JIS K-6714.

(Humidity dependence of film Re and Rth)
It is preferable that both the in-plane retardation Re and the thickness direction retardation Rth of the transparent film of the present invention have small changes due to humidity. Specifically, the difference ΔRth (= Rth10% RH−Rth80% RH) between the Rth value at 25 ° C. and 10% RH and the Rth value at 25 ° C. and 80% RH is preferably 0 to 50 nm. More preferably, it is 0-40 nm, More preferably, it is 0-35 nm.

(Equilibrium moisture content of film)
The equilibrium moisture content of the transparent film of the present invention is such that when used as a protective film for a polarizing plate, the adhesiveness with a water-soluble polymer such as polyvinyl alcohol is not impaired. It is preferable that the equilibrium water content in is 0 to 4%. It is more preferably 0.1 to 3.5%, and particularly preferably 1 to 3%. When the equilibrium moisture content is 4% or more, the dependency of retardation due to humidity change becomes too large when used as a support for an optical compensation film.
The water content was measured by measuring the transparent film sample 7 mm × 35 mm of the present invention by the Karl Fischer method using a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both Mitsubishi Chemical Corporation). It was calculated by dividing the amount of water (g) by the sample weight (g).

(Water permeability of film)
The moisture permeability of the transparent film used in the optical compensation sheet of the present invention is measured under the conditions of a temperature of 60 ° C. and a humidity of 95% RH based on JIS standard JISZ0208, and converted to a film thickness of 80 μm, 400 to 2000 g / m ^2.・ It should be 24h. More preferably 500~1800g / m ² · 24h, and particularly preferably 600~1600g / m ² · 24h. If it exceeds 2000 g / m ² · 24 h, the tendency of the absolute value of the humidity dependence of the Re value and Rth value of the film to exceed 0.5 nm /% RH becomes strong. Also, when an optically anisotropic film is formed by laminating an optically anisotropic layer on the transparent film of the present invention, the absolute value of the humidity dependence of the Re value and Rth value tends to exceed 0.5 nm /% RH. This is not preferable. When this optical compensation sheet or polarizing plate is incorporated in a liquid crystal display device, it causes a change in color and a decrease in viewing angle. In addition, when the moisture permeability of the transparent film is less than 400 g / m ² · 24 h, when the polarizing plate is produced by being attached to both surfaces of the polarizing film, the transparent film prevents the adhesive from being dried, resulting in poor adhesion.
If the film thickness of the transparent film is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. Therefore, it is necessary to convert the sample of any film thickness to a standard of 80 μm. The conversion of the film thickness was obtained as (water permeability in terms of 80 μm = measured moisture permeability × measured film thickness μm / 80 μm).
The measurement method of moisture permeability is “Polymer Physical Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation amount (mass method, thermometer method, vapor pressure method, adsorption amount method) The transparent film sample 70 mmφ of the present invention was conditioned at 25 ° C., 90% RH, 60 ° C., and 95% RH for 24 hours, respectively, and a moisture permeability test apparatus (KK-709007, Toyo Seiki Co., Ltd.) calculated the amount of water per unit area (g / m ² ) according to JIS Z-0208, and determined moisture permeability = weight after humidity adjustment−weight before humidity adjustment.

(Dimensional change of film)
The dimensional stability of the transparent film of the present invention is such that the dimensional change rate when left standing for 24 hours under conditions of 60 ° C. and 90% RH (high humidity) and 24 hours under conditions of 90 ° C. and 5% RH. It is desirable that the dimensional change rate after standing (high temperature) is 0.5% or less.
More preferably, it is 0.3% or less, and even more preferably, it is 0.15% or less.
As a specific measurement method, two transparent film samples 30 mm × 120 mm were prepared, humidity-controlled at 25 ° C. and 60% RH for 24 hours, and an automatic pin gauge (Shinto Kagaku Co., Ltd.) with 6 mmφ at both ends. Holes were drilled at intervals of 100 mm to obtain the original punch spacing (L0). Punch interval size (L1) after one sample was treated at 60 ° C. and 90% RH for 24 hours, punch after one sample was treated at 90 ° C. and 5% RH for 24 hours The spacing dimension (L2) was measured. Measurement was made to a minimum scale of 1/1000 mm at all intervals. Dimensional change rate of 60 ° C. and 90% RH (high humidity) = {| L0−L1 | / L0} × 100, Dimensional change rate of 90 ° C. and 5% RH (high temperature) = {| L0−L2 | / The dimensional change rate was determined as L0} × 100.

(Elastic modulus of film)
Elastic modulus of the transparent film of the present invention is preferably ^{200~500kgf / mm 2 (1960~4900N / mm} 2), more preferably ^{240~470kgf / mm 2 (2350~4610N / mm} 2), more preferably from ^{270~440kgf / mm 2 (2650~4315N / mm} 2). As a specific measurement method, Toyo Baldwin Universal Tensile Tester STM T50BP was used to measure the stress at 0.5% elongation in a 23 ° C, 70% atmosphere at a pulling rate of 10% / min to obtain the elastic modulus. It was.

(Photoelastic coefficient of film)
The photoelastic coefficient of the transparent film of the present invention is preferably 50 × 10 ⁻¹³ cm ² / dyne or less. It is more preferably 30 × 10 ⁻¹³ cm ² / dyne or less, and further preferably 20 × 10 ⁻¹³ cm ² / dyne or less. As a specific measuring method, a tensile stress is applied to the long axis direction of a transparent film sample 12 mm × 120 mm, the retardation at that time is measured with an ellipsometer (M150, JASCO Corporation), and the letter to the stress is measured. The photoelastic coefficient was calculated from the amount of change in the foundation.

(Film surface properties)
The surface of the transparent film of the present invention preferably has an arithmetic average roughness (Ra) of surface irregularities of the film based on JIS B0601-1994 of 0.1 μm or less and a maximum height (Ry) of 0.5 μm or less. . Preferably, the arithmetic average roughness (Ra) is 0.05 μm or less, and the maximum height (Ry) is 0.2 μm or less. The concave and convex shapes on the film surface can be evaluated by an atomic force microscope (AFM).

(Retention of film)
In the transparent film of the present invention, retention of various compounds added to the film is required. Specifically, the mass change of the film when the transparent film of the present invention is allowed to stand for 48 hours under the condition of 80 ° C./90% RH is preferably 0 to 5%. More preferably, it is 0 to 3%, and still more preferably 0 to 2%.
<Method for evaluating holdability>
The sample was cut to a size of 10 cm × 10 cm, and the mass after being allowed to stand for 24 hours in an atmosphere of 23 ° C. and 55% RH was measured, and left for 48 hours under the conditions of 80 ± 5 ° C. and 90 ± 10% RH. . The surface of the sample after the treatment was lightly wiped, the mass after standing for 1 day at 23 ° C. and 55% RH was measured, and the retention was calculated by the following method.
Retention property (mass%) = {(mass before standing−mass after standing) / mass before standing} × 100

(curl)
The curl value in the width direction of the transparent film of the present invention is preferably −10 / m to + 10 / m. When the surface treatment described below is applied to the transparent film of the present invention, the rubbing treatment when applying the optically anisotropic layer, the orientation film, the application or pasting of the optically anisotropic layer, etc. are performed in a long length. When the curl value in the width direction of the transparent film of the present invention is outside the above range, the film handling may be hindered and the film may be cut. In addition, the film is strongly in contact with the transport roll at the edge and center of the film, so it is easy to generate dust, and foreign matter adheres to the film. May exceed the value. Further, by setting the curl in the above-mentioned range, it is possible to reduce color spot failures that are likely to occur when the optically anisotropic layer is installed, and it is possible to prevent bubbles from entering when the polarizing film is bonded, which is preferable.
The curl value can be measured according to a measurement method (ANSI / ASCPH1.29-1985) defined by the American National Standards Institute.

(Tear strength)
The tear strength (Elmendorf tear method) based on the tear test method of JISK7128-2: 1998 is preferably 2 g or more in the range where the film thickness of the transparent film of the present invention is 20 to 80 μm. More preferably, it is 5-25g, Furthermore, it is 6-25g. Moreover, 8 g or more is preferable at 60 micrometer conversion, More preferably, it is 8-15g. Specifically, it can be measured using a light load tear strength tester after conditioning a sample piece of 50 mm × 64 mm under the conditions of 25 ° C. and 65% RH for 2 hours.

(Residual solvent amount of film)
It is preferable to dry on the conditions which the amount of residual solvents with respect to the transparent film of this invention becomes the range of 0.01-1.5 mass%. More preferably, it is 0.01-1.0 mass%. Curling can be suppressed by setting the residual solvent amount of the transparent support used in the present invention to 1.5% or less. More preferably, it is 1.0% or less. This is probably because free deposition is reduced by reducing the amount of residual solvent during film formation by the above-described solvent casting method.

(Hygroscopic expansion coefficient of film)
The hygroscopic expansion coefficient of the transparent film of the present invention is preferably 30 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably 15 × 10 ⁻⁵ /% RH or less, and more preferably 10 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably small, but usually it is 1.0 × 10 ⁻⁵ /% RH or more. The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature. By adjusting the coefficient of hygroscopic expansion, when the transparent film of the present invention is used as an optical compensation film support, while maintaining the optical compensation function of the optical compensation film, the frame-shaped transmittance rises, that is, the light leaks due to distortion. Can be prevented.

[Usage]
The transparent film of the present invention is applied to optical applications, photographic light-sensitive materials and the like. The optical application is preferably a liquid crystal display device, and the transparent film of the present invention can be used as a transparent protective film for a polarizing element. The liquid crystal display device includes a liquid crystal cell having a liquid crystal supported between two electrode substrates, two polarizing elements disposed on both sides thereof, and at least one sheet between the liquid crystal cell and the polarizing element. More preferably, the optical compensation sheet is arranged. As these liquid crystal display devices, TN, IPS, FLC, AFLC, OCB, STN, ECB, VA and HAN are preferable.

[Functional layer]
When using the transparent film of this invention for the above optical uses, it is possible to provide various functional layers in a transparent film. Examples of the functional layer include an antistatic layer, a cured resin layer (transparent hard coat layer), an antireflection layer, an easy adhesion layer, an antiglare layer, an optical compensation layer, an alignment layer, a liquid crystal layer, and the like. Surfactants, slip agents, matting agents and the like can be added to the layer. Examples of the functional layer applicable to the transparent film of the present invention include those described in pages 32 to 45 of the Japan Society for Invention and Innovation (Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is done.
Moreover, when using as another use, you may provide functional layers, such as a subbing layer and a back layer, in a transparent film.

(Hard coat film, antiglare film, antireflection film)
The transparent film of the present invention is provided with a hard coat layer, an antiglare layer and an antireflection layer on one or both sides of the transparent film of the present invention for the purpose of improving the visibility of flat panel displays such as LCD, PDP, CRT and EL. Any or all of them are preferably used as a hard coat film, an antiglare film, or an antireflection film. Preferred embodiments of such an antiglare film and antireflection film are described in detail in pages 54 to 57 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). It is described and can be applied to the transparent film of the present invention.

[surface treatment]
The transparent film of the present invention can be surface treated as necessary. By performing the surface treatment, the adhesion between the transparent film and the functional layer (for example, the undercoat layer and the back layer) can be improved.
As the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 in the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, Issued on March 15, 2001, Invention Association). In the present invention, The described compounds can be preferably used.

(Contact angle of film surface by alkali saponification treatment)
When the transparent film of the present invention is used as a transparent protective film for a polarizing plate, surface treatment by alkali saponification treatment is effective. In this case, the contact angle of the film surface after the alkali saponification treatment is preferably 55 ° or less, more preferably 50 ° or less, and further preferably 45 ° or less.
The contact angle is used as one of indices for evaluating hydrophilicity / hydrophobicity. For the measurement of the contact angle, a normal method can be used. Specifically, a method in which a water droplet having a diameter of 3 mm is dropped on the surface of the film after the alkali saponification treatment and the angle formed by the film surface and the water droplet is used. it can.

[Application (Polarizing plate)]
The transparent film of the present invention is particularly useful for a polarizing plate protective film. When using as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. Specifically, the transparent film of the present invention is saponified by alkali treatment, and the saponified transparent film is completely saponified polyvinyl alcohol aqueous solution on both sides of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution. There is a method to stick together. Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed.
Examples of the adhesive used for bonding the treated surface of the transparent film and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like.

The polarizing plate is generally composed of a polarizer and protective films for protecting both surfaces of the polarizer, but a protective film may be bonded to one surface of the polarizing plate and a separate film may be bonded to the opposite surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the contact bonding layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate.
In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates. However, the polarizing plate protective film to which the transparent film of the present invention is applied exhibits excellent display properties regardless of the location. It is done. In particular, the polarizing plate protective film on the outermost surface of the display side of the liquid crystal display device is provided with a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like. Therefore, the polarizing plate protective film using the transparent film of the present invention in this portion Is preferably arranged.

[Application (Optical compensation film)]
The transparent film of the present invention can be used in various applications, but is particularly effective when used as an optical compensation film for a liquid crystal display device by providing an optically anisotropic layer on the transparent film. The optical compensation film is generally used for a liquid crystal display device, refers to an optical material that compensates for a phase difference, and is synonymous with a phase difference plate, an optical compensation sheet, and the like. The optical compensation film has birefringence and is used for the purpose of removing the color of the display screen of the liquid crystal display device or improving the viewing angle characteristics.

When the transparent film of the present invention is used as an optical compensation film for a liquid crystal display device, it is not limited to the optical performance or driving method of the liquid crystal cell of the liquid crystal display device used, and any optical properties required as an optical compensation film are required. An anisotropic layer can also be provided.
The optically anisotropic layer of the optical compensation film of the present invention is preferably an optically anisotropic layer satisfying the following formula (iii).
(Iii) Re ₍₅₉₀₎ = 0 to 200 (nm) and | Rth ₍₅₉₀₎ | = 0 to 300 (nm)
The optically anisotropic layer may be formed from a composition containing a liquid crystalline compound or may be formed from a polymer film having birefringence. As the liquid crystal compound, a discotic liquid crystal compound or a rod-like liquid crystal compound is preferable.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds that can be used in the present invention include various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan). , Quarterly Chemistry Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985). J. Zhang et al., J. Am.Chem.Soc., Vol.116, page 2655 (1994)).

The discotic liquid crystalline compound preferably has a polymerizable group so that it can be fixed by polymerization. As the discotic liquid crystalline compound having a polymerizable group, for example, a structure in which a polymerizable group is bonded as a substituent to a discotic core of the discotic liquid crystalline compound can be considered. However, if a polymerizable group is directly connected to the disc-shaped core, it may be difficult to maintain the orientation state in the polymerization reaction. Therefore, a structure having a linking group between the discotic core and the polymerizable group is preferable. That is, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula.
D (-LP) n
In the formula, D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 4 to 12. Preferred specific examples of the discotic core (D), the divalent linking group (L) and the polymerizable group (P) in the above formula are (D1) to (D15) described in JP-A No. 2001-4837, respectively. ), (L1) to (L25), and (P1) to (P18).

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles. As the rod-like liquid crystalline compound, in addition to the low molecular liquid crystalline compounds exemplified above, a high molecular liquid crystalline compound can also be used.

  In the optically anisotropic layer, the rod-like liquid crystalline molecules are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. Examples of polymerizable rod-like liquid crystalline compounds that can be used in the present invention include those described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, International Publications (WO) 95/22586, 95/24455. No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, and Examples thereof include compounds described in JP-A No. 2001-328773.

(Optically anisotropic layer made of polymer film)
The optically anisotropic layer may be formed from a polymer film. The polymer film is formed from a polymer that can exhibit optical anisotropy. Examples of such polymers include polyolefins (eg, polyethylene, polypropylene, norbornene polymers), polycarbonates, polyarylate, polysulfone, polyvinyl alcohol, polymethacrylic acid esters, polyacrylic acid esters and cellulose esters (eg, cellulose triacetate, Cellulose diacetate). Further, a copolymer or a polymer mixture of these polymers may be used.

  The optical anisotropy of the polymer film is preferably obtained by stretching. The stretching is preferably uniaxial stretching or biaxial stretching. Specifically, longitudinal uniaxial stretching using a difference in peripheral speed between two or more rolls, tenter stretching for grasping both sides of the polymer film and stretching in the width direction, or biaxial stretching in combination of these is preferable. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 500 μm, and most preferably 40 to 100 μm.

  Further, as the polymer film forming the optically anisotropic layer, at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide, and polyaryletherketone is used, A method in which a solution obtained by dissolving this in a solvent is applied to a substrate and the solvent is dried to form a film can be preferably used. At this time, a method of stretching the polymer film and the base material to develop optical anisotropy and using it as an optical anisotropic layer can be preferably used, and the transparent film of the present invention is preferably used as the base material. Can do. Alternatively, the polymer film may be prepared on another substrate, and the polymer film may be peeled off from the substrate and then bonded to the transparent film of the present invention, and used as an optically anisotropic layer. preferable. In this method, the thickness of the polymer film can be reduced, and is preferably 50 μm or less, and more preferably 1 to 20 μm.

[Usage (Liquid Crystal Display)]
The liquid crystal display device of the present invention is a liquid crystal cell in which a liquid crystal is supported between two electrode substrates, and two polarizers disposed on both sides thereof. The liquid crystal cell, the polarizer, It is desirable that at least one optical compensation film is disposed between them.
The transparent film of the present invention can be used in a liquid crystal display device as a protective film for a polarizer. Further, as described above, an optically anisotropic film is provided on a transparent film to form an optical compensation film, and this optical compensation film can be used for a liquid crystal display device by disposing it between a liquid crystal cell and a polarizer. . When the transparent film of the present invention is used as an optical compensation film, the transmission axis of the polarizer and the slow axis of the optical compensation film provided with the transparent film may be arranged at any angle.
Note that the liquid crystal layer of the liquid crystal cell used in the liquid crystal display device of the present invention is usually formed by enclosing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on the substrate as a transparent film containing a conductive substance. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer, or an undercoat layer (undercoat layer) (used for adhesion of the transparent electrode layer). These layers are usually provided on the substrate. The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.

(Types of liquid crystal display devices)
The transparent film of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroly Liquid Liquid Crystal), OCB (Optically Liquid BTS). Various display modes such as ECB (Electrically Controlled Birefringence) and HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed. The transparent film of the present invention is effective in any display mode liquid crystal display device. Further, it is effective in any of a transmissive type, a reflective type, and a transflective liquid crystal display device.

(TN type liquid crystal display device)
You may use the transparent film of this invention as a support body or polarizing plate protective film of the optical compensation film of a TN type liquid crystal display device which has a TN mode liquid crystal cell. A TN mode liquid crystal cell and a TN type liquid crystal display device are conventionally known. The optical compensation sheet used in the TN type liquid crystal display device is described in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068). is there.

(STN type liquid crystal display device)
You may use the transparent film of this invention as a support body or polarizing plate protective film of the optical compensation film of the STN type liquid crystal display device which has a liquid crystal cell of STN mode. In general, in a STN type liquid crystal display device, rod-like liquid crystalline molecules in a liquid crystal cell are twisted in the range of 90 to 360 degrees, and the refractive index anisotropy (Δn) and cell gap (d) of the rod-like liquid crystalline molecules. Product (Δnd) is in the range of 300 to 1500 nm. The optical compensation film used for the STN type liquid crystal display device is described in JP-A No. 2000-105316.

(VA type liquid crystal display device)
The transparent film of the present invention may be used as a support for an optical compensation film or a polarizing plate protective film for a VA liquid crystal display device having a VA mode liquid crystal cell. It is preferable that the Re retardation value of the optical compensation film used in the VA liquid crystal display device is 0 to 150 nm and the Rth retardation value is 70 to 400 nm. The Re retardation value is more preferably 20 to 70 nm. When two optical compensation films are used in a VA liquid crystal display device, the Rth retardation value of the film is preferably 70 to 250 nm. When one optical compensation film is used for the VA liquid crystal display device, the Rth retardation value of the film is preferably 150 to 400 nm. The VA-type liquid crystal display device may be an alignment-divided system as described in, for example, JP-A-10-123576.

(IPS liquid crystal display device and ECB liquid crystal display device)
The transparent film of the present invention is also particularly advantageously used as a support for an optical compensation film of an IPS liquid crystal display device and an ECB liquid crystal display device having IPS mode and ECB mode liquid crystal cells, or as a protective film for a polarizing plate. In these modes, the liquid crystal material is aligned substantially in parallel during black display, and black is displayed by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, the polarizing plate using the transparent film of the present invention contributes to widening the viewing angle and improving the contrast. In this aspect, the retardation value of the protective film of the polarizing plate and the optically anisotropic layer disposed between the protective film and the liquid crystal cell is set to be not more than twice the value of Δn · d of the liquid crystal layer. Is preferred. In addition, since the absolute value | Rth | of the Rth value is preferably set to 25 nm or less, more preferably 20 nm or less, and even more preferably 15 nm or less, the transparent film of the present invention is advantageously used.

(OCB type liquid crystal display device and HAN type liquid crystal display device)
The transparent film of the present invention may be used as a support for an optical compensation film or a polarizing plate protective film of an OCB type liquid crystal display device having an OCB mode liquid crystal cell or a HAN type liquid crystal display device having a HAN mode liquid crystal cell. In the optical compensation film used for the OCB type liquid crystal display device or the HAN type liquid crystal display device, it is preferable that the direction in which the absolute value of retardation is minimum does not exist in the plane of the optical compensation film or in the normal direction. The optical properties of the optical compensation film used in the OCB type liquid crystal display device or the HAN type liquid crystal display device are the same as the optical properties of the optical anisotropic layer, the optical properties of the support, and the optical anisotropic layer and the support. Is determined by the arrangement of An optical compensation film used for an OCB type liquid crystal display device or a HAN type liquid crystal display device is described in JP-A-9-197397. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 38 (1999) p. 2837).

(Reflective liquid crystal display)
The transparent film of the present invention may be used as an optical compensation film or a polarizing plate protective film for a TN type, STN type, HAN type, GH (Guest-Host) type reflective liquid crystal display device. These display modes have been well known since ancient times. The TN type reflection type liquid crystal display device is described in JP-A-10-123478, WO98848320, and Japanese Patent No. 3022477. The optical compensation film used for the reflection type liquid crystal display device is described in WO00-65384.

(Other liquid crystal display devices)
The transparent film of the present invention may be used as a support for an optical compensation sheet or a polarizing plate protective film of an ASM type liquid crystal display device having a liquid crystal cell in an ASM (Axial Symmetrical Microcell) mode. The ASM mode liquid crystal cell is characterized in that the thickness of the cell is maintained by a resin spacer whose position can be adjusted. Other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device are described in a paper by Kume et al. (Kume et al., SID 98 Digest 1089 (1998)).

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the technical idea of the present invention, and the scope of the present invention is not limited to the specific examples shown below.

[Preparation of cellulose acylate film]
Example 1-1
(Preparation of cellulose acylate film 101)
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acetate solution A was prepared.

<Composition of cellulose acylate solution A>
Cellulose acetate with a substitution degree of 2.86 100 parts by weight Methylene chloride (first solvent) 517.6 parts by weight Methanol (second solvent) 77.3 parts by weight Silica particles with an average particle diameter of 16 nm 0.13 parts by weight (AEROSIL R972, Nippon Aerosil Co., Ltd.)
Compound for reducing optical anisotropy (A-7) 12.0 parts by mass

The cellulose acylate solution A was cast using a drum cooled to −10 ° C., and the film was peeled off from the drum with a residual solvent amount of 280% and conveyed by a tenter. At this time, the tenter conditions were adjusted so that the force applied to the film was within an appropriate range. The average temperature of the drying zone was 140 ° C., and the film was formed at a speed of 100 m / min.
The finished cellulose acylate film 101 had a residual solvent amount of 0.15%, a film width of 1400 mm, and a film thickness of 80 μm.
Table A shows the Re, Rth, the thermal expansion coefficient in the machine direction, the thermal expansion coefficient in the direction perpendicular to the machine direction, and the ratio of the thermal expansion coefficient in the machine direction to the thermal expansion coefficient in the direction perpendicular to the machine direction. Show.

Example 1-2
(Preparation of cellulose acylate film 102)
A cellulose acylate film 102 was produced in the same manner except that the cellulose acylate solution was changed to the following composition in Example 1. Table A shows the physical properties of the obtained film.

<Cellulose acylate solution B composition>.
Cellulose acetate with an average degree of acetylation of 2.93 100.0 parts by mass Methylene chloride (first solvent) 517.6 parts by mass Methanol (second solvent) 77.3 parts by mass Silica particles with an average particle size of 16 nm 0.13 parts by mass (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
Compound (A-19) for reducing optical anisotropy 25.7 parts by weight Wavelength dispersion adjusting agent (UV-102) 1.2 parts by weight Citrate ester 0.01 parts by weight

Example 1-3
(Preparation of cellulose acylate film 103)
In Example 1, the cellulose acylate solution was changed to the following composition, a band was used as the endless support instead of the drum, the residual volatile content at the time of stripping was 60%, and the film was formed at a film forming speed of 40 m / min. A cellulose acylate film 103 was produced in the same manner except for the above. Table A shows the physical properties of the obtained film.

<Composition of cellulose acylate solution C>
Cellulose acetate with an average degree of acetylation of 2.93 100.0 parts by mass Methylene chloride (first solvent) 517.6 parts by mass Methanol (second solvent) 77.3 parts by mass Silica particles with an average particle size of 16 nm 0.13 parts by mass (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
Compound (A-19) for reducing optical anisotropy 11.7 parts by weight Wavelength dispersion adjusting agent (UV-102) 1.2 parts by weight Citrate ester 0.01 parts by weight

Comparative Example 1-1
(Preparation of cellulose acylate film 108)
A cellulose acylate film 108 was produced in the same manner except that the cellulose acylate solution in Example 1 was changed to the following composition. Table A shows the physical properties of the obtained film.

<Composition of cellulose acylate solution D>
Average degree of acetylation 2.88 Cellulose triacetate 100 parts by weight Methylene chloride (first solvent) 320 parts by weight Methanol (second solvent) 83 parts by weight 1-butanol (third solvent) 3 parts by weight Silica particles having an average particle size of 16 nm 0 .13 parts by mass (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
Triphenyl phosphate 7.6 parts by mass Biphenyl, diphenyl phosphate 3.8 parts by mass Citrate 0.006 parts by mass

Examples 1-4 to 1-7, Comparative Example 1-2
(Production of cellulose acylate films 104 to 107, 109)
Cellulose acylate films 104 to 107 and 109 were produced in the same manner as in Example 1 except that the cellulose acylate solution, the film forming speed, and the tenter adjustment conditions were changed as shown in Table A. Table A shows the physical properties of the obtained film.

[Creating a polarizing plate]
Example 2-1
(Preparation of polarizing plate 101X)
The cellulose acylate film 101 was continuously passed through a 1.5 mol / L sodium hydroxide aqueous solution and immersed at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing tub, and neutralized using the 0.1 mol / L sulfuric acid at 30 degreeC. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. In this way, the surface of the cellulose acylate film 101 was saponified.
Subsequently, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an iodine aqueous solution and dried to obtain a polarizing film having a thickness of 20 μm. Using a 3% aqueous solution of polyvinyl alcohol (Kuraray PVA-117H) as an adhesive, two saponified cellulose acylate films 101 are prepared and bonded with a roll-to-roll with a polarizing film in between. A polarizing plate 101X protected by the rate film 101 was obtained.

Examples 2-2 to 2-7, Comparative Examples 2-1 and 2-2
Polarizing plates 102X to 109X were produced in the same manner as in Example 2-1, except that any of the cellulose acylate films 102 to 109 was used instead of the cellulose acylate film 101.

[Evaluation of mounting on panel]
Example 3-1.
The polarizing plate 101X of the present invention was mounted on a panel of a liquid crystal display device and evaluated.

[IPS mode]
<Polarizing plate for IPS liquid crystal cell>
A polyester film having a dimensional change rate (MD / TD) of 1.15 at 165 degrees is adhered to both sides of a polycarbonate having a length of 100 m, a width of 180 mm, a thickness of 80 μm and a Re of 0 nm via an acrylic adhesive layer, and a roll. The polyester film was peeled off after shrinking the polycarbonate by treatment in a room temperature atmosphere with a roll speed ratio of 0.97 and a roll temperature of 165 ° C. using a stretching machine. This retardation plate was stretched 1.1 times in the width direction under an atmosphere of 163 degrees to obtain an optical compensation film Z1.
Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependence of Re was measured, and when these optical characteristics were calculated, Re was 270 nm and Nz was 0. 0.5, and it was confirmed that the slow axis was in a direction perpendicular to the longitudinal direction.
A polarizing plate-integrated optical compensation film 101Z1 was produced by pasting on one side of the polarizing plate 101X of the present invention so that the slow axis of the optical compensation film Z1 and the absorption axis of the polarizing plate coincide.

<Production of IPS mode liquid crystal cell>
On one glass substrate, electrodes were arranged so that the distance between adjacent electrodes was 20 μm, and a polyimide film was provided as an alignment film thereon, and a rubbing treatment was performed. A polyimide film was provided on one surface of a separately prepared glass substrate, and a rubbing treatment was performed to obtain an alignment film. The two glass substrates are stacked and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 3.9 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.
The polarizing plate of the present invention is attached to the light source side of the liquid crystal cell with an adhesive so that the slow axis of the liquid crystal cell coincides with the absorption axis of the polarizing plate, and the opposite polarizing plate and absorption axis are on the opposite side of the liquid crystal cell. An IPS liquid crystal display device was prepared by attaching the optical compensation film side of the polarizing plate-integrated optical compensation film 101Z1 to the liquid crystal cell side so as to be orthogonal to each other and sticking with an adhesive.

[VA mode]
(Optical compensation film for VA)
Using the cellulose acylate film 101, an optical compensation film sample was produced according to the method described in Example 1 of JP-A No. 2003-315541. Synthesis from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) A solution prepared by adding 25 wt% of a polyimide having a weight average molecular weight (Mw) of 70,000 and Δn of about 0.04 to cyclohexanone as a solvent was applied to the cellulose acetate film 101. Then, after heat treatment at 100 ° C. for 10 minutes, 15% longitudinal uniaxial stretching was performed at 160 ° C. to obtain an optical compensation film in which a 6 μm-thick polyimide film was applied to the transparent film of the present invention. The optical properties of this optical compensation film were Re = 72 nm, Rth = 220 nm, the misalignment angle of the orientation axis was within ± 0.3 degrees, and an optical compensation film Z2 having a birefringent layer of nx>ny> nz.

<Production of VA liquid crystal cell>
1% by weight of octadecyldimethylammonium chloride (coupling agent) was added to a 3% by weight aqueous solution of polyvinyl alcohol. This was spin-coated on a glass substrate with an ITO electrode and heat-treated at 160 ° C. to form a vertical alignment film. Two glass substrates face each other, and a liquid crystal compound (Δn: 0.06) mainly composed of an ester group and an ethane group is injected into the cell gap, so that a product of Δn and d is 300 nm. A cell was produced.
The side of the optical compensation film Z2 on which the polyimide film was not applied was subjected to alkali saponification treatment and adhered to the polarizer with a polyvinyl alcohol-based adhesive, thereby being directly bonded to the polarizer. Further, Fujitac TD80UF (manufactured by Fuji Photo Film Co., Ltd.) subjected to alkali saponification treatment was similarly bonded to the polarizer as a protective film opposite to the optical compensation film Z2 with the polarizer interposed therebetween. At this time, a polarizing plate integrated optical compensation film 101Z2 was obtained so that the slow axis of the optical compensation film and the absorption axis of the polarizing plate were orthogonal to each other. The polarizing plate integrated optical compensation film 101Z2 was bonded to the VA liquid crystal panel with an adhesive so that the optical compensation film side was the liquid crystal cell side. In addition, on the opposite side of the liquid crystal cell, only the polarizing plate (polarizing plate with Fujitac TD80UF as protective films on both sides) is bonded to the VA liquid crystal panel via an adhesive so that the absorption axes of the polarizing plates are orthogonal to each other. A liquid crystal display device was created.

(Panel evaluation)
<Evaluation of viewing angle characteristics and durability of the manufactured liquid crystal display device>
The viewing angle dependence of the transmittance of the prepared liquid crystal display device was measured. The suppression angle was measured from the front to the diagonal direction up to 80 ° every 10 °, and the azimuth angle was measured up to 360 ° every 10 ° on the basis of the horizontal right direction (0 °). It was found that the luminance at the time of black display increased as the angle of suppression increased from the front direction, and the leaked light transmittance also increased and took a maximum value near the angle of suppression of 70 °. It was also found that the contrast deteriorates as the black display transmittance increases. Therefore, it was decided to evaluate the viewing angle characteristics with the maximum values of the black display transmittance at the front and the leaked light transmittance at an angle of 60 °.
Further, as a durability test, display unevenness after treatment for 500 hours at 60 ° C. and 90% RH was observed. Unevenness occurred mainly at the four corners of the panel.
The results obtained are shown in Table B.
<Evaluation of display characteristics>
Evaluation of viewing angle characteristics ◎: Very little difference in viewing angle characteristics is good ○: Little difference in viewing angle characteristics ×: Evaluation of durability with large difference in viewing angle characteristics ◎: Very little unevenness ○: Very little unevenness x: Unevenness is large

Examples 3-2 to 3-7, Comparative Examples 3-1 and 3-2
<IPS polarizing plate for IPS liquid crystal cell> An IPS liquid crystal display using each polarizing plate in the same manner as in Example 3-1, except that any of polarizing plates 102X to 109X is used instead of the polarizing plate 101X. A device was made.
Further, in the (VA optical compensation film), each cellulose acylate film is used in the same manner as in Example 3-1, except that any of the cellulose acylate films 102 to 109 is used instead of the cellulose acylate film 101. A VA liquid crystal display device was produced.
Table B shows the results of panel evaluation in the same manner as in Example 3-1.

  It can be seen that a liquid crystal display device using a film whose optical characteristics and thermal expansion coefficient are within the range of the present invention has both excellent viewing angle characteristics and durability, and has excellent display performance.

Claims (10)

At least one of the thermal expansion coefficient in the machine direction (αMD) or the thermal expansion coefficient in the direction perpendicular to the machine direction (αTD) is 1.0 × 10 ⁻⁵ to 10 × 10 ⁻⁵ / ° C., and The thermal expansion coefficient in the machine direction is 0.4 to 1.0 times the thermal expansion coefficient in the direction perpendicular to the machine direction, and the retardation value Re in the film plane and the retardation value Rth in the film thickness direction are A transparent film characterized by satisfying the following formulas (i) and (ii):
(I) 0 ≦ Re ₍₅₉₀₎ ≦ 20
(Ii) | Rth ₍₅₉₀₎ | ≦ 25
[In the formula, Re ₍ λ ₎ is an in-plane retardation value (unit: nm) at a wavelength λnm, and Rth ₍ λ ₎ is a retardation value (unit: nm) in the film thickness direction at a wavelength λnm. ]   The transparent film according to claim 1, comprising cellulose acylate.   The transparent film according to claim 1 or 2, wherein a polymer material is dissolved in a solvent to prepare a dope, the dope is cast on an endless support, continuously peeled off, and dried to produce a film. A method for producing a transparent film, wherein the film-forming speed is 50 to 300 m / min, and at least one of a tension applied in a machine direction and a tension applied in a direction perpendicular to the machine direction is adjusted. An optically anisotropic layer having an in-plane retardation value Re and a retardation value Rth in the film thickness direction satisfying the following formula (iii) is provided on the transparent film according to claim 1 or 2. An optical compensation film.
(Iii) Re ₍₅₉₀₎ = 0 to 200 (nm) and | Rth ₍₅₉₀₎ | = 0 to 300 (nm)   The optical compensation film according to claim 4, wherein the optically anisotropic layer contains a discotic liquid crystalline compound.   The optical compensation film according to claim 4, wherein the optically anisotropic layer contains a rod-like liquid crystalline compound.   The optical compensation film according to claim 4, wherein the optically anisotropic layer is a polymer film having birefringence.   A polarizing plate comprising the transparent film according to claim 1 or 2 or the optical compensation film according to any one of claims 4 to 7 as a protective film for a single polarizer.   A liquid crystal display device comprising at least one of the transparent film according to claim 1, the optical compensation film according to claim 4, or the polarizing plate according to claim 8.   The liquid crystal display device according to claim 9, wherein the liquid crystal display device is of a VA or IPS type.