JP2007039505A - Cellulose acylate film and polarizing plate using the same and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film capable of being used for a polarizing plate-protecting film from cellulose acylate film chips containing an easily photo-decomposable additive at a low cost, to provide a polarizing plate using the cellulose acylate film, and to provide a liquid crystal display. <P>SOLUTION: This cellulose acylate film produced by mix-dissolving cellulose acylate film chips comprising a cellulose acylate and an additive capable of being decomposed by the irradiation of light and then forming the film is characterized by having a transmittance change of ≤15.0% at 400 nm between transmittances before and after irradiated with a standard daylight color xenon light at an irradiance of 150 W/m<SP>2</SP>in an atmosphere of 60°C and 50% R.H. for ten days, and having a transmittance change of ≤3.0% at 550 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thin film display, in particular, a liquid crystal display device used for a monitor for a personal computer, a television, etc., a polarizing plate incorporated in the display device, a protective film for a polarizing plate, a retardation film, and the like.

In recent years, many types of image display devices such as liquid crystal display devices, organic EL display devices, and PDPs have been developed. In particular, the market for liquid crystal display devices is expanding, centering on televisions and monitors. In the liquid crystal display device, a polarizing plate and a retardation film are used outside the liquid crystal cell, and a cellulose triacetate film is used as a protective film for the polarizing plate.
In general, a cellulose acylate film is formed by a solution casting method. That is, cellulose acylate is dissolved in a solvent, a plasticizer and, if necessary, a dye are added to adjust the dope, and the film is cast on a support to form a film. In the dope preparation process, in order to reduce manufacturing costs, not only new cellulose acylate, but also a method of adding a certain amount of chips that have been crushed from cutting edge scraps generated during the film forming process, as well as chip scraps generated during film forming process switching It has been known.

  Cellulose acylate films are also being studied for retardation film applications. For example, cellulose triacetate films used for polarizing plates are conventionally known to have a small retardation, but they can be used as retardation films by providing desired optical performance as retardation films by various methods. Has been. Among them, the method of adding an additive to a cellulose acylate film is particularly preferably used because the optical performance in a wide range can be adjusted depending on the kind and the added amount, and the same production apparatus as in the past can be used. Regarding the retardation film made of cellulose acylate as described above, it is desired to reuse a chip in which scraps are crushed. In fact, in the case of a cellulose acylate film made of the same material, it is generally performed to reuse chips that have been crushed.

  Recently, retardation films made of various cellulose acylates have been developed corresponding to the modes and specifications of liquid crystal display devices. For this reason, it has become desirable to reuse chips made from cellulose acylate film scraps that are not the same material.

  In order to solve such a problem, a method is considered in which the additive is removed from the film waste to obtain only cellulose acylate (for example, Patent Documents 1 and 2).

JP 2002-172618 A JP2004203963

However, in the methods disclosed in Patent Documents 1 and 2, there are not a few cases where removal is difficult depending on the type of additive. In addition, there is a problem that the manufacturing cost becomes high.
Further, since the retardation film is disposed inside the polarizing plate and the liquid crystal cell, an additive that is not sufficiently durable against external light may be used. Conventionally, a film chip using such an additive is used. If the cellulose acylate used in the protective film is used in combination, the performance as a conventional protective film, that is, the light absorption performance in the ultraviolet region and the transmittance in the visible region may be impaired. Moreover, even if there is no problem at the time of manufacture, there is a problem that it gradually deteriorates with time, and these solutions are required.

  The subject of this invention is providing the cellulose acylate film which can be used for a polarizing plate protective film at low cost using the cellulose acylate film chip containing the additive which is easy to decompose | disassemble with light. Another object of the present invention is to provide a polarizing plate and a liquid crystal display device using the cellulose acylate film.

The problem was achieved by the following means.
(1) A cellulose acylate film obtained by forming a solution obtained by mixing cellulose acylate and a cellulose acylate film chip containing an additive that is decomposed by light irradiation and dissolving in a solvent, the cellulose acylate film The rate of change in transmittance at 400 nm before and after the rate film was irradiated with xenon light (JIS Z8301 <standard daylight xenon light source>) at an irradiance of 150 W / m ² in an atmosphere of 60 ° C. and 50% RH was 15 A cellulose acylate film having a transmittance of 0.0% or less and a change in transmittance at 550 nm of 3.0% or less.
(2) The cellulose acylate film as described in (1) above, which contains a compound having a wavelength (λmax) giving an absorption maximum of an ultraviolet absorption spectrum of from 250 nm to 380 nm.
(3) The cellulose acylate has at least two maximum points of the acyl substitution degree distribution, and the maximum value of the difference in the acyl substitution degree of any two of the plurality of maximum points is 0.15 or less. The cellulose acylate film as described in (1) or (2) above.
(4) The cellulose reed according to any one of (1) to (3) above, wherein at least one layer selected from a hard coat layer, an antireflection layer and an antiglare layer is provided on at least one surface. Rate film.

(5) A polarizing plate, wherein the protective film provided on at least one side of the polarizing plate is the cellulose acylate film according to any one of (1) to (4).
(6) A liquid crystal display device using at least one polarizing plate according to (5).
(7) A liquid crystal display device comprising a cellulose acylate film containing an additive that decomposes by light irradiation on the viewing side of the liquid crystal display device.
(8) A cellulose acylate film obtained by mixing a cellulose acylate film chip and a cellulose acylate film chip containing an additive that is decomposed by light irradiation and dissolving in a solvent is formed on the viewing side of the liquid crystal display device. (7) The liquid crystal display device as described in (7) above.
(9) The liquid crystal display device according to any one of (6) to (8), wherein the liquid crystal cell is in an IPS mode or a VA mode.

  The cellulose acylate film of the present invention, which is obtained from a mixture of cellulose acylate and a cellulose acylate film chip containing an additive that is decomposed by light irradiation, has no fluctuation in absorption performance in the ultraviolet region, and The rate of change in the visible transmittance when exposed to light is sufficiently low, eliminating the negative effects associated with the use of the chip described in the section on the solution. Therefore, it can be used at low cost for optical films such as polarizing plates, protective films, retardation films, and antiglare films, and they can be provided as components of liquid crystal display devices.

  Details of the present invention will be described below.

[Composition of cellulose acylate film]
(Tips to be reused)
In the cellulose acylate film of the present invention, a chip obtained by cutting a cellulose acylate film containing an additive that is decomposed by light irradiation (also referred to as a cellulose acylate film chip or simply a chip) is used as a part of the raw material. The additive that decomposes when irradiated with light is xenon light (JIS Z8301 <standard daylight xenon light source>) in a film formed by adding only the additive to cellulose acylate in an environment of 60 ° C. and 50% RH. ) With an irradiance of 150 W / m ² for 10 days indicates an additive in which 1% or more of the existing amount decomposes. The content of the additive is preferably 1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and most preferably 1% by mass or more and 10% by mass or less with respect to the chip weight. If it is 20% by mass or more, it becomes difficult to adjust the amount of change in transmittance within the scope of the claims without affecting the phase difference performance. In order to determine the amount of UV absorber added to adjust the transmittance change amount, the amount of additive decomposed by light irradiation contained in the chip to be used should be examined in advance using a generally known method. Is desirable. In order to make the amount of the photodecomposable compound contained in the cellulose acylate film within a preferable range, it is desirable to adjust the amount of chip used. The chip may contain an additive other than the additive that is decomposed by light irradiation.
In addition, the above-mentioned “chip to be reused” is “reuse” in the sense that a film produced as a cellulose acylate film containing an additive that is decomposed by light irradiation is cut and used as a chip. It does not necessarily mean a chip obtained by cutting a used film.

  The type of the substituent of the cellulose acylate used for the chip is not particularly limited, but is preferably the same as the type of the substituent of the cellulose acylate used for the dope to which the chip is added. The cellulose acylate film of the present invention prepared by mixing chips is most preferably one point of maximum degree of acyl substitution distribution, but the degree of acyl substitution at the maximum point is at least two points. If the difference is 0 or more and 0.15 or less, it can be used. It is preferably 0 or more and 0.13 or less, and more preferably 0 or more and 0.10 or less. If it is 0.15 or more, it may become cloudy and the actual harm may not be ignored. Here, the substitution degree distribution of the cellulose acylate can be measured by, for example, a known method described in JP-A-9-77801.

  There is no restriction | limiting in particular about the manufacturing method of a chip | tip, It can carry out by a known method. The chip size is not particularly limited as long as it does not affect the preparation of the dope used in the present invention.

  The amount of the chip used is desirably 0.1% by mass or more and 50% by mass or less based on the newly used cellulose acylate. 0.1 mass% or more and 40 mass% or less are still more preferable, and 0.1 mass% or more and 30 mass% or less are the most preferable. When it is 50 mass% or more, it becomes difficult to adjust the amount of change in transmittance within the scope of the claims.

(UV absorber)
The cellulose acylate film of the present invention preferably uses an ultraviolet absorber in order to obtain a desired transmittance change amount, and among them, the wavelength (λmax) that gives the absorption maximum of the ultraviolet absorption spectrum of the solution is 250 nm or more and 380 nm or less. A compound can be preferably used. λmax is more preferably 260 nm to 350 nm, and most preferably 280 nm to 350 nm. When λmax is 380 nm or more, the film is likely to be colored. On the other hand, when λmax is 250 nm or less, the ultraviolet absorption is insufficient, and the transmittance in the ultraviolet region is greatly reduced by light irradiation, resulting in fluctuations in the light absorption characteristics.
The aspect ratio of the ultraviolet absorber used in the present invention is not particularly limited, but is particularly preferably 2.0 or less. The aspect ratio is defined by the length (a) in the molecular principal axis direction and the length (b) in the direction perpendicular to the principal axis. Here, the length of the molecular principal axis and the length in the direction perpendicular to the principal axis can be obtained by calculating the most stable molecular structure in terms of energy using commercially available molecular calculation software or the like. When the aspect ratio is 2 or more, in the film forming process, it becomes easy to develop retardation by orientation due to drawing for conveyance and tension in the width direction for maintaining flatness.
The addition amount of the ultraviolet absorber is desirably 20% by mass or less, more desirably 15% by mass or less, and most desirably 10% or less. If it exceeds 20% by mass, the influence of retardation is not negligible. Further, although it depends on the amount of other additives, precipitation (bleed out) is likely to occur in the film forming process. It is desirable that the amount of the ultraviolet absorber be as small as possible within the range in which the transmittance change amount according to the present invention can be achieved in accordance with the content of the photodegradable additive contained in the chip.

(Change in film transmittance before and after light irradiation)
The cellulose acylate film of the present invention is transmitted at 400 nm before and after irradiation with xenon light (JIS Z8301 <standard daylight xenon light source>) at an irradiance of 150 W / m ² for 10 days in an atmosphere of 60 ° C. and 50% RH. It is desirable that the rate change amount is 15.0% or less and the transmittance change amount at 550 nm is 3.0% or less. Here, the transmittance is 25 ° C., 60% R.D. H. It is obtained by measuring using a spectrophotometer (for example, U-3210, Hitachi, Ltd.) under the environment of The amount of change in transmittance at 400 nm is more preferably 0% or more and 13% or less, further preferably 0% or more and 10% or less, and most preferably 0% or more and 5% or less. The change in transmittance at 550 nm is more preferably 0% or more and 2.0% or less, further preferably 0% or more and 1.0% or less, and most preferably 0% or more and 0.5% or less. Within these ranges, even if a film is installed on the viewing side of the liquid crystal display device, the display performance is not greatly degraded by light irradiation, and there is no practical problem.

(Cellulose acylate)
Examples of the cellulose raw material for the cellulose acylate film used in the present invention include cotton linter and wood pulp (hardwood pulp, softwood pulp), and any cellulose acylate obtained from any cellulose raw material can be used. Moreover, you may mix and use depending on the case. Detailed descriptions of these raw material celluloses can be found in, for example, Plastic Materials Course (17) Fibrous Resin (Maruzawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Open Technical Report 2001-1745 (page 7). To page 8) can be used, and the cellulose acylate film of the present invention is not particularly limited.
Cellulose acylate 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 used in the present invention, the degree of substitution of cellulose with a hydroxyl group is not particularly limited. The degree of substitution of cellulose acylate in the present invention can be obtained by measuring the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms to be substituted for the hydroxyl group of cellulose and calculating based on the measured value. As a measuring method, it can carry out according to ASTM D-817-91. The degree of substitution when the hydroxyl group of cellulose is 100% substituted is 3.
Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms may be an aliphatic group or an allyl group, and is not particularly limited. However, it may be a mixture of two or more groups.

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 may be difficult due to casting. Moreover, when the polymerization degree is too low, the strength of the produced film may be lowered. The viscosity average degree of polymerization can be measured by Uda et al.'S limiting viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). This is described in detail in JP-A-9-95538.
Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) is small, and molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 5.0, more preferably 1.0 to 4.5, and most preferably 1.0 to 4.0. preferable.

  When the low molecular weight component in the cellulose acylate 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 with a low low molecular weight component can be obtained, for example, by removing the low molecular component from cellulose acylate synthesized by a usual method. The removal of the low molecular weight 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 weight 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. Regarding the cellulose acylate used in the present invention, the raw material cotton and the synthesis method are described in detail on pages 7 to 12 in the Japan Society for Invention and Innovation (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in. If the cellulose acylate used in the present invention has the substituent, substitution degree, polymerization degree, molecular weight distribution, etc. within the ranges described above, a single layer or two or more different types of cellulose acylate may be mixed in one layer. Can be used.

In the present invention, it is preferable to produce a cellulose acylate film by a solvent cast method, and it is preferred to produce a film using a solution (dope) in which cellulose acylate is dissolved in an organic solvent. As the main solvent of the organic solvent for dissolving cellulose acylate, a solvent selected from esters, ketones, ethers having 3 to 12 carbon atoms and halogenated hydrocarbons having 1 to 7 carbon atoms is preferable. 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 the main solvent, such as an alcoholic hydroxyl group. It may have other functional groups. 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, for the cellulose acylate film of the present invention, a chlorinated halogenated hydrocarbon may be used as a main solvent, and as described in JIII Journal of Technical Disclosure 2001-1745 (pages 12 to 16), A non-chlorinated solvent may be used as the main solvent, and is not particularly limited for the cellulose acylate film in the present invention.
In addition, the solvent for the cellulose acylate solution and film used in the present invention is disclosed in the following documents including the dissolution method, and the preferred embodiments are also the same. They are, for example, JP-A No. 2000-95876, JP-A No. 12-95877, JP-A No. 10-324774, JP-A No. 8-152514, JP-A No. 10-330538, and JP-A No. 9-95538. JP-A-9-95557, JP-A-10-235664, JP-A-12-63534, JP-A-11-21379, JP-A-10-182853, JP-A-10-278056, JP-A-10 -297702, JP-A-10-323853, JP-A-10-237186, JP-A-11-60807, JP-A-11-152342, JP-A-11-292988, JP-A-11-60752. No. 1, JP-A-11-60752, and the like. According to these documents, not only the preferable solvent for the cellulose acylate in the present invention but also the physical properties of the solution and the coexisting substances to be coexisted are described, which is also a preferable embodiment in the present invention.

(Additive)
In the cellulose acylate solution for producing the cellulose acylate film in the present invention, various additives depending on the use in each preparation step, for example, a compound that reduces optical anisotropy, optical anisotropy Compounds other than those expressed (for example, see JP-A No. 2000-111194 and WO 00/65384), wavelength dispersion adjusting agents (for example, see WO 00/65384), plasticizers, and ultraviolet absorbers used for adjusting the transmittance change amount of the present invention UV external absorbers, deterioration inhibitors, fine particles, peeling accelerators, etc.) can be added. Moreover, the addition time may be added at any time in the dope preparation step, but may be added at the end of the dope preparation step by adding an additive and adjusting it.

The compound that lowers the optical anisotropy (that is, the retardation-reducing compound) is preferably compatible with cellulose acylate, and the compound itself does not have a rod-like structure or a planar structure. Specifically, when the retardation-reducing compound has a plurality of planar functional groups such as aromatic groups, a structure having these functional groups not on the same plane but on a non-planar surface is advantageous.
The molecular weight of the retardation reducing compound is preferably 150 to 3000, preferably 170 to 2000, and particularly preferably 200 to 1000. As long as these molecular weights are within the range, a specific monomer structure may be used, or an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used. The retardation reducing compound 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 solid having a melting point of 25 to 200 ° C. . Further, the retardation reducing compound is preferably not volatilized in the process of dope casting and drying during the production of the cellulose acylate film. The addition amount of the retardation reducing compound is preferably 0.01 to 30% by mass of cellulose acylate, more preferably 1 to 25% by mass, and particularly preferably 5 to 20% by mass. . The retardation-reducing compound may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.
From the viewpoint of solubility in cellulose acylate, the retardation reducing agent used in the present invention is preferably a compound having an octanol-water partition coefficient (log P value) of 0 to 7. 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 the compound having a log P value of less than 0 has high hydrophilicity, the water resistance of the cellulose acetate film may be deteriorated. A more preferable range for 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 permeation method described in JIS Japanese Industrial Standard Z7260-107 (2000).

  Other than the plasticizer, the ultraviolet absorber for adjusting the transmittance change amount according to the present invention, the ultraviolet external absorber, the deterioration preventing agent, and the like may be solid or oily. For these details, materials described in detail on pages 16 to 22 of the Japan Institute of Invention Disclosure Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Invention Association) are preferably used.

It is preferable that fine particles are added as a matting agent to the cellulose acylate film in 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 in terms of low turbidity, and silicon dioxide is particularly preferable. The silicon dioxide fine particles preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more. A primary particle having an average diameter as small as 5 to 16 nm is more preferable because the haze of the film can be lowered. The apparent specific gravity of the silicon dioxide is more preferably 90 to 200 g / liter or more, and particularly 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 nm to 3.0 μm. These fine particles exist as aggregates of primary particles in the film, and can form irregularities of 0.1 to 3.0 μm on the film surface. The secondary average particle diameter is preferably 0.2 μm to 1.5 μm or less, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. The primary and secondary particle sizes of the fine particles 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 the silicon dioxide fine particles, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, manufactured by 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.

  The peeling accelerator added to the cellulose acylate solution as necessary is not particularly limited, and a known surfactant can be used. In particular, phosphoric acid, sulfonic acid, carboxylic acid, nonionic, and cationic surfactants can be preferably used, and carboxylic acid surfactants can be most preferably used. Specifically, for example, compounds described in JP-A-61-243837 can be used.

  In the cellulose acylate film used in the present invention, the total amount of compounds having a molecular weight of 3000 or less is preferably 5 to 45% by mass, more preferably 10 to 40% by mass, based on the cellulose acylate mass. More preferably, it is 15-30 mass%. As described above, these compounds include retardation reducing compounds, retardation developing compounds, wavelength dispersion adjusting agents, ultraviolet ray inhibitors, plasticizers, deterioration preventing agents, fine particles, peeling accelerators, and the molecular weight is 3000 or less. Is preferable, 2000 or less is more preferable, and 1000 or less is more preferable. When the total amount of these compounds is 5% by mass 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. There is a case. In addition, when the total amount of these compounds is 45% or more, the compound exceeds the limit of compatibility of the compounds in the cellulose acylate film, and precipitates on the film surface and the film becomes cloudy (so-called crying from the film). May be likely to occur.

[Manufacturing process of cellulose acylate film]
(Dissolution process)
The cellulose acylate and chips in the present invention are used by mixing before dissolving in a solvent. The method for preparing the cellulose acylate solution (dope) is not particularly limited, and may be room temperature, or 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.

(Casting process)
Next, a method for producing a film using the cellulose acylate solution in the present invention will be described. The method and equipment for producing a cellulose acylate film in the present invention can use a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is once stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent 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, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support.
The film forming method is not particularly limited, and a band casting method or a cooling casting method generally known as a method for forming a cellulose acylate film can be used. A co-casting method may be used.
The step of casting on the support is preferably covered with a certain space and a nitrogen atmosphere. The optimum temperature can be selected depending on the film forming method. The amount of residual solvent contained in the web at the time of stripping defined by the following formula (I) varies depending on the casting method, and 40% to 80% if it is a general method in which the dope surface temperature is close to room temperature. % Is preferable, 45% to 75% is more preferable, and 50% to 70% is most preferable. In the cooling casting method in which the dope surface temperature is set to 10 ° C. or less, the casting is preferably 100% to 300%, more preferably 130% to 270%, and most preferably 150% to 250%. preferable.

The cooling casting can be performed, for example, by the method disclosed in JP-A-62-115035.
Formula (I)
Residual solvent amount at stripping (%) = (film weight at stripping−film weight at zero residual solvent amount) / (film mass at zero residual solvent amount) × 100

(Stretching and drying process)
In this invention, the both ends of the web obtained at the casting process may be hold | maintained, and you may perform an extending | stretching process as needed. The draw ratio is adjusted according to the target optical performance, but the drawing is performed at a draw ratio of 1 to 200%. The stretching is preferably 1 to 100%, particularly preferably 1 to 50%.

The film is stretched at room temperature or under heating conditions. The heating temperature is preferably not higher than the glass transition temperature of the film. Although there is no restriction | limiting in particular in a heating method, The method of introduce | transducing the wind set to predetermined temperature into a tenter part is forced compulsorily. In order to reduce in-plane variations in the slow axis direction, a wind control plate may be provided, or a known method such as a back heater may be used.
The stretching of the film may be uniaxial stretching only in the transverse direction, or may be simultaneous or longitudinal biaxial stretching and sequential biaxial stretching. However, there is a method using transverse stretching from the viewpoint of producing a smooth planar film with small thickness unevenness. preferable. The method of stretching in the film width direction is not particularly limited, and can be carried out by a known method, but tenter stretching is preferred in which both ends of the film are sandwiched with dedicated clips to expand and contract. In order to improve the uniformity in the width direction in the slow axis direction, it is preferable that the expansion / contraction width in the tenter can be adjusted at four or more locations. It is more preferable that 6 or more points can be adjusted, and it is most preferable that the adjustment is performed at 8 or more and 15 or less. If the number is less than 4, it is difficult to finely adjust the uniformity in the width direction. If the number is 15 or more, it becomes complicated and difficult to adjust during manufacturing.

The method for drying the cellulose acylate film of the present invention is not particularly limited, but a method of drying while mechanically transporting in a drying section composed of a plurality of roll groups is preferably used. In the case of performing stretching using the tenter described above, the film can be detached from the clip after the tenter process is completed, and then dried in a drying section composed of a plurality of roll groups.
The drying temperature is desirably 100 ° C. or higher and 150 ° C. or lower, preferably 100 ° C. or higher and 140 ° C. or lower, and most preferably 110 ° C. or higher and 140 ° C. or lower. When the temperature is lower than 100 ° C., drying is difficult to proceed, and it is difficult to obtain a film in which the solvent is sufficiently dried. On the other hand, when the temperature is 150 ° C. or higher, the glass transition temperature of the film is often exceeded, and the film may be stretched in the length direction to cause unnecessary retardation. Here, the drying temperature is the temperature when a sensor such as a thermocouple is attached to the film being dried, but when using the method of introducing heated air to dry, the temperature of the air supply port and the exhaust port Management by temperature In general, the supply air temperature is higher than the film surface temperature, and the exhaust temperature is the same as or slightly lower than the film surface temperature, and therefore, the temperature is controlled within the temperature range that satisfies the above film surface temperature. When using a method of heating using radiant heat, it is better to measure using a fixed sensor near the film surface.

The film after drying is wound up to a predetermined length in a roll by a winder. You may provide the curl improvement part etc. by steam immediately before winding.
In the solution casting film forming method used for the functional protective film which is an optical member for an electronic display, which is the main use of the cellulose acylate film in the present invention, in addition to the solution casting film forming apparatus, the subbing is performed. In many cases, a coating apparatus is added for surface processing of a film such as a layer, an antistatic layer, an antihalation layer, or a protective layer. These are described in detail on pages 25 to 30 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Institute of Invention), and should be preferably used as appropriate in the present invention. Can do.

  10-120 micrometers is preferable, as for the thickness of the cellulose acylate film produced as mentioned above, 20-100 micrometers is more preferable, and 30-90 micrometers is further more preferable. The residual solvent amount of the film is preferably 3% or less, more preferably 2% or less, and most preferably 1% or less.

(Surface treatment of cellulose acylate film)
The cellulose acylate film may optionally be subjected to a surface treatment to improve the adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer). 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 is a treatment for subjecting the film surface to a plasma treatment in the presence of a plasma-excitable gas.
The glow discharge treatment includes a low temperature plasma treatment performed under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa). Plasma treatment under atmospheric pressure is also an example of a preferable glow discharge treatment. A plasma-excitable gas is a gas that is plasma-excited under the above-described conditions, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. 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), and can be preferably used in the present invention. it can.
In the present invention, alkali saponification is one effective means of surface treatment when a cellulose acylate film is used as a transparent protective film for a polarizing plate. In this case, the contact angle of the film surface after the alkali saponification treatment is preferably 55 ° or less. More preferably, it is 50 ° or less, and further preferably 45 ° or less. The contact angle evaluation method is an ordinary method for obtaining an angle formed by dropping a water droplet having a diameter of 3 mm on the surface of the film after the alkali saponification treatment to determine the angle formed by the film surface and the water droplet, and can be used for evaluating hydrophilicity / hydrophobicity.

(Hard coat layer, antireflection layer, antiglare layer)
The cellulose acylate film of the present invention is provided with at least one of a hard coat layer, an antireflection layer and an antiglare layer on at least one of the cellulose acylate films in order to achieve the transmittance change amount described in the claims. Is preferred. These layers can be appropriately selected according to the required display quality and surface characteristics.

The hard coat _layer, light or heat, or it is formed by crosslinking reaction or polymerization reaction of both compounds curable by preferred. The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound. Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 0/46617.
The hard coat layer used in the present invention preferably contains an ultraviolet absorber. The maximum absorption wavelength (λmax) of the ultraviolet absorption spectrum is not particularly limited, but is preferably in the range of 250 nm to 400 nm, and most preferably 300 nm to 400 nm. There is no restriction | limiting in particular in content, It can add arbitrarily in the range which does not affect a photocrosslinking reaction.
The hard coat layer can also serve as an antiglare layer containing particles having an average particle size of 0.2 to 10 μm and imparted with an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.

  It is desirable that the antireflection layer and antiglare layer used in the present invention contain the aforementioned ultraviolet absorber. The content is not particularly limited to the maximum absorption wavelength (λmax) and content of the ultraviolet absorption spectrum, and can be arbitrarily added within a range that does not affect the formation and fixation of the antiglare layer. The structure of the antireflection layer and the antiglare layer is not particularly limited, and is formed by laminating two to three layers having different refractive indexes, and a resin containing a filler such as silicon dioxide (silica) is applied to the surface of the film. Formed by coating a translucent resin solution containing translucent particles having a refractive index different from the translucent resin within a predetermined range, translucent in the translucent resin An anti-glare layer having a known configuration such as a resin configured to include translucent particles of particles and matte particles having different refractive indexes within a predetermined range can be provided.

(Polarizer)
The cellulose acylate film of the present invention is preferably used as a polarizing plate protective film. In the present invention, the type of polarizing plate is not particularly limited as long as the content of the present invention is satisfied. For example, a polyvinyl alcohol (PVA) film is dyed with iodine having a dichroism or a dichroic dye. An absorption type polarizing plate produced by bonding with a protective film and a polarizer that has been stretched and oriented and then cross-linked and dried can be preferably used. The polarizer is preferably excellent in light transmittance and degree of polarization. The light transmittance is preferably 30% to 50%, more preferably 35% to 50%, and most preferably 40% to 45%. The degree of polarization is preferably 90% or more, more preferably 95% or more, and most preferably 99% or more. When the transmittance is 30% or less or the degree of polarization is 90% or less, the brightness and contrast of the image display device are low, and the display quality is deteriorated. The thickness of the polarizer is preferably 1 to 50 μm, more preferably 10 to 40 μm, and most preferably 15 to 35 μm.
In the present invention, the adhesion treatment between the polarizer and the protective film is not particularly limited. For example, an adhesive made of a vinyl alcohol polymer, boric acid, borax, glutaraldehyde, melamine, oxalic acid, etc. It can be carried out through an adhesive composed at least of a water-soluble crosslinking agent for vinyl alcohol polymers. In particular, it is preferable to use an adhesive made of a vinyl alcohol polymer because it has the best adhesion to the polyvinyl alcohol film. Such an adhesive layer can be formed as a coating / drying layer of an aqueous solution, but other additives and a catalyst such as an acid can be blended as necessary when preparing the aqueous solution.

  In general, a film containing a material that undergoes photodegradation has a problem of being colored with time due to sunlight or the like. Therefore, it is difficult to use the protective film on the viewing side of a polarizing plate used in a liquid crystal panel. The acylate film can be used without any problem on the viewing side or the liquid crystal cell side.

  If necessary, an optical compensation film may be used on the liquid crystal cell side of the polarizing plate. The optical compensation film generally refers to an optical material that compensates for a viewing angle in an oblique direction of a liquid crystal display device, and is synonymous with a retardation plate, an optical compensation sheet, and the like. The optical compensation film may be an integral type in which the protective film of the polarizing plate itself has optical performance, for example, a triacetyl cellulose acylate film having optical compensation performance to form a protective film for a polarizer. A type in which a discotic liquid crystal is applied to an acetylcellulose film and then integrated with a polarizing plate may be used. Moreover, you may adhere | attach on a polarizing plate via an adhesive, and you may bond together using a some optical compensation film. As the optical compensation film to be bonded, a polymer film is mainly preferably used. For example, 2 such as a polymer film having birefringence stretched biaxially in the plane direction, or a tilted orientation polymer film having a controlled refractive index in the thickness direction stretched uniaxially in the plane direction and also stretched in the thickness direction. A direction stretched film or the like is used. Furthermore, an inclined alignment film is also used. For example, a heat-shrinkable film is adhered to a polymer film, and a polymer film is stretched or / and contracted under the action of the shrinkage force by heating, or a liquid crystal polymer is obliquely oriented.

(Liquid crystal display device)
Details of the liquid crystal display device used in the present invention will be described below.

  The liquid crystal display device can be achieved by using liquid crystal cells of various display modes. Typical display modes include In-Plane Switching (IPS), Vertically Aligned (VA), Twisted Nematic (TN), Optically Compensated Bend (OCB), and Super Twisted Bend (STN). Various display modes have been proposed such as Ferroelectric Liquid Crystal (AFLC), Anti-Ferroelectric Liquid Crystal (AFLC), and Hybrid Aligned Nematic (HAN). In addition, a display mode in which the above display mode is oriented and divided has been proposed. The cellulose acylate film of the present invention can be effectively used particularly for IPS, VA, and OCB modes used for large TV applications.

  The IPS mode is a mode in which liquid crystal molecules are always rotated in a horizontal plane with respect to the substrate, and is aligned so as to have a slight angle with respect to the longitudinal direction of the electrode when no electric field is applied. When an electric field is applied, the liquid crystal molecules change direction in the direction of the electric field. The light transmittance can be changed by arranging the polarizing plates sandwiching the liquid crystal cell at a predetermined angle. As a liquid crystal molecule, a nematic liquid crystal having a positive dielectric anisotropy Δε is used. The thickness (gap) of the liquid crystal layer is more than 2.8 μm and less than 4.5 μm. This is because when the retardation Δn · d is more than 0.25 μm and less than 0.32 μm, a transmittance characteristic having almost no wavelength dependency within the visible light range can be obtained. By combining the polarizing plates, the maximum transmittance can be obtained when the liquid crystal molecules are rotated 45 ° from the rubbing direction to the electric field direction. The liquid crystal molecules are not particularly limited as long as they are nematic liquid crystals. The larger the value of the dielectric anisotropy Δε, the lower the driving voltage, and the smaller the refractive index anisotropy Δn, the thicker the liquid crystal layer (gap), the shorter the liquid crystal sealing time, In addition, gap variation can be reduced.

  In the VA mode, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845, in which the VA mode is converted into a multi-domain (MVA mode) in order to enlarge the viewing angle. (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied. -59 pages (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

The OCB mode is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. OCB mode liquid crystal cells are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are aligned symmetrically between the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. For this reason, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.

  The present invention will be described more specifically with reference to the following examples. However, the scope of the present invention is not limited to the specific examples shown below.

[Example 1]
(1-1) Preparation of recovery chip 100 parts by mass of cellulose acylate having an acetyl substitution degree of 2.96, 12 parts by mass of a compound represented by chemical formula (I), and a compound represented by chemical formula (II) (λmax = 326 nm) Waste generated in the process of forming a cellulose acylate film produced using 2 parts by mass was collected and cut into chips of about several mm to 3 cm to form chips (called collection chips).
Separately, a cellulose acylate film using 100 parts by mass of cellulose acylate and 12 parts by mass of the compound described in chemical formula (I) was prepared, and commercially available xenon light (JIS Z8301 <standard daylight xenon light source>) in an environment of 60 ° C. Was irradiated for 10 days at an irradiance of 150 W / m ² , the abundance of chemical formula (I) before and after irradiation was determined by high performance liquid chromatography, and the photodecomposition rate was calculated to be 16%.
Chemical formula (I)

Chemical formula (II)

(1-2) Preparation of Cellulose Acylate Film 1 The following composition was put into a mixing tank and stirred to disperse or dissolve each component to prepare a cellulose acylate solution A.

  20 parts by mass of silica particles having an average particle diameter of 16 nm (AELOSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were thoroughly stirred and mixed for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to disperse or dissolve each component to prepare a mat material solution A.

  The following composition was put into a mixing tank and stirred while heating to disperse or dissolve each component to prepare additive solution A.

Chemical formula (III)

Chemical formula (IV)

  The cellulose acylate solution A, 94.6 parts by mass, the mat material solution A, 1.3 parts by mass, and the additive solution A, 2.4 parts by mass, were mixed after filtration, respectively, and the casting part, tenter part, and drying were mixed. It cast using the band casting machine comprised from a part. The film cast on the band was peeled off in a state containing a residual solvent amount of about 55%, and then dried at 95 ° C. while holding both ends with a tenter. Furthermore, after leaving the tenter at a residual solvent amount of about 20%, both ends with clip marks were cut off, and then dried in a temperature range of 100 to 130 ° C. in a drying section comprising a plurality of rolls and wound up. The film thickness of the cellulose acylate film 1 thus obtained was 80 μm.

(1-3) Xenon Irradiation Test A sample having a size of about 2 cm × 7 cm was cut out from the obtained cellulose acylate film 1, and transmittances at 400 nm and 550 nm were obtained with a spectrophotometer (manufactured by Shimadzu Corporation). Next, xenon light was irradiated for 10 days under conditions of 150 W / m ² , 60 ° C. and 50% RH with a super xenon weather meter SX-75 (manufactured by Suga Test Instruments Co., Ltd.). After the elapse of a predetermined time, the film was taken out from the thermostatic bath and conditioned at 25 ° C. and 60% RH for 2 hours, and the transmittances at 400 nm and 550 nm were measured again to determine the amount of change in transmittance. The results are shown in Table 1.

[Example 2]
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution B.

  94.6 parts by mass of the cellulose acylate solution B, 1.3 parts by mass of the mat material solution A prepared in Example 1, and 4.1 parts by mass of the additive solution A were mixed after filtration, respectively. It cast using the band casting machine comprised from a tenter part and a drying part. The film cast on the band was peeled off in a state containing a residual solvent amount of about 55%, and then dried at 95 ° C. while holding both ends with a tenter. Furthermore, after leaving the tenter at a residual solvent amount of about 20%, both ends with clip marks were cut off, and then dried in a temperature range of 100 to 130 ° C. in a drying section comprising a plurality of rolls and wound up. The film thickness of the cellulose acylate film 2 thus obtained was 80 μm.

  About the obtained cellulose acylate film 2, the xenon irradiation test was done like Example 1. FIG. The results are shown in Table 1.

[Example 3]
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution C.

  The cellulose acylate solution C was 94.6 parts by mass, the mat material solution A prepared in Example 1 was 1.3 parts by mass, and the additive solution A was 4.1 parts by mass. It cast using the band casting machine comprised from a tenter part and a drying part. The film cast on the band was peeled off in a state containing a residual solvent amount of about 55%, and then dried at 95 ° C. while holding both ends with a tenter. Furthermore, after leaving the tenter at a residual solvent amount of about 20%, both ends with clip marks were cut off, and then dried in a temperature range of 100 to 130 ° C. in a drying section comprising a plurality of rolls and wound up. The film thickness of the cellulose acylate film 3 thus obtained was 80 μm.

  About the obtained cellulose acylate film 3, the xenon irradiation test was done like Example 1. FIG. The results are shown in Table 1.

[Example 4]
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution D.

  The cellulose acylate solution D was 94.6 parts by mass, the mat material solution A prepared in Example 1 was 1.3 parts by mass, and the additive solution A was 4.1 parts by mass. It cast using the band casting machine comprised from a tenter part and a drying part. The film cast on the band was peeled off in a state containing a residual solvent amount of about 55%, and then dried at 95 ° C. while holding both ends with a tenter. Furthermore, after leaving the tenter at a residual solvent amount of about 20%, both ends with clip marks were cut off, and then dried in a temperature range of 100 to 130 ° C. in a drying section comprising a plurality of rolls and wound up. The film thickness of the cellulose acylate film 4 thus obtained was 80 μm.

  About the obtained cellulose acylate film 4, the xenon irradiation test was done like Example 1. FIG. The results are shown in Table 1.

[Example 5]
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution E.

  94.6 parts by mass of the cellulose acylate solution E, 1.3 parts by mass of the mat material solution A prepared in Example 1, and 4.1 parts by mass of the additive solution A were mixed after filtration, respectively, It cast using the band casting machine comprised from a tenter part and a drying part. The film cast on the band was peeled off in a state containing a residual solvent amount of about 55%, and then dried at 95 ° C. while holding both ends with a tenter. Further, after leaving the tenter at a residual solvent amount of about 20%, both ends with clip marks were cut off, and then dried and wound up in a temperature range of 100 to 130 ° C. in a drying section comprising a plurality of rolls. The film thickness of the cellulose acylate film 5 thus obtained was 80 μm.

  The obtained cellulose acylate film 5 was subjected to a xenon irradiation test in the same manner as in Example 1. The results are shown in Table 1.

[Example 6]
250 g of Desolite KZ-7869 (ultraviolet curable hard coat composition, 72 mass%, manufactured by JSR Corporation) and 3 g of the following compound were dissolved in a mixed solvent of 62 g of methyl ethyl ketone and 88 g of cyclohexanone, and a hard coat layer coating solution was obtained. Prepared. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.53.
Compound (V)

91 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.), 199 g of Desolite KZ-7115, KZ-7161 (ZrO ₂ fine particle dispersion, manufactured by JSR Co., Ltd.) 52 g of methyl ethyl ketone / cyclohexanone was dissolved in a mixed solvent of 54/46% by mass. 10 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) was added to the obtained solution. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.61. Further, 20 g of crosslinked polystyrene particles having an average particle size of 2.0 μm (SX-200H, manufactured by Soken Chemical Co., Ltd.) was added to this solution in a mixed solvent of 80 g of methyl ethyl ketone / cyclohexanone = 54/46 mass% at a high speed disperser at 5000 rpm. 29 g of a dispersion obtained by stirring and dispersing for a time was added and stirred, and then filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution for an antiglare layer.

The hard coat layer coating solution is applied to one side of the cellulose acylate film 2 using a bar coater, dried at 120 ° C., and then a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.). Then, the coating layer was cured by irradiating ultraviolet rays having an irradiance of 400 mW / cm ² and an irradiation amount of 300 mJ / cm ² to form a hard coat layer having a thickness of 4 μm. Further, the antiglare layer coating solution is applied using a bar coater, dried at 120 ° C. in an oxygen concentration atmosphere of 0.01% or less by nitrogen purge, and then an air-cooled metal halide lamp (160 W / cm) Using an iGraphics Co., Ltd.), an ultraviolet ray having an irradiance of 400 mW / cm ² and an irradiation amount of 300 mJ / cm ² is irradiated to cure the coating layer, and an anti-glare hard coat layer having a thickness of 1.4 μm is formed. Formed. In this way, a cellulose acylate film 6 was prepared.

  The obtained cellulose acylate film 6 was subjected to a xenon irradiation test in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution F.

  94.6 parts by mass of the cellulose acylate solution F, 1.3 parts by mass of the mat material solution A prepared in Example 1, and 4.1 parts by mass of the additive solution A were mixed after filtration, respectively, Casting was performed in the same manner as in Example 1 using a band casting machine composed of a tenter unit and a drying unit. The film thickness of the cellulose acylate film 7 thus obtained was 80 μm.

  About the obtained cellulose acylate film 7, the xenon irradiation test was done like Example 1. FIG. The results are shown in Table 91.

[Example 7]
(Creation of polarizing plate)
The cellulose acylate film 1 prepared in Example 1 was immersed in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing bath, and neutralized using 0.05 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, both surfaces of the film were saponified.

Next, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer. A polarizing plate 1 was prepared by bonding two saponified cellulose acylate films 1 using a 3% aqueous solution of polyvinyl alcohol (PVA-117H, manufactured by Kuraray) as an adhesive, and bonding them to a polarizer.
Similarly, polarizing plates 2 to 5 using cellulose acylate films 2 to 5 were prepared.

[Example 8]
The cellulose acylate film 6 and a commercially available cellulose triacetate film (TD80U manufactured by Fuji Photo Film Co., Ltd.) were saponified in the same manner as in Example 7. Next, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer. One side of the polarizer is placed so that the side opposite to the antiglare layer of the cellulose acylate film 6 is adjacent to the polarizer, and a commercially available cellulose triacetate film is placed on the other side of the polarizer, and polyvinyl alcohol (PVA-made by Kuraray) is placed. 117H) A 3% aqueous solution was bonded as an adhesive to prepare a polarizing plate 6.

[Comparative Example 2]
A polarizing plate 7 was produced in the same manner as in Example 7 except that the cellulose acylate film 7 was used.

[Example 9]
(Creation of IPS liquid crystal display device)
A polarizing plate and a retardation plate provided in a commercially available liquid crystal display device (HITACHI L5000, 32 inch size) using an IPS liquid crystal cell were peeled off, and the liquid crystal cell was taken out. An optical compensation film (in-plane retardation 270 nm, NZ factor 0.5) uniaxially stretched with polarizing plate 1 and Arton film (manufactured by JSR) is attached to the front side (viewing side) of the liquid crystal cell using an acrylic adhesive. Combined. Next, the polarizing plate 1 was bonded to the back side of the liquid crystal cell using the same adhesive material. The liquid crystal panel thus prepared was reassembled to prepare a liquid crystal display device.
About the created liquid crystal display device, the above-mentioned standard daylight xenon light is used with Super Xenon Weather Meter SX-75 (manufactured by Suga Test Instruments Co., Ltd.) under the conditions of irradiance 150 W / m ² , 60 ° C. and 50% RH Were irradiated for 10 days. Almost no change in color was observed after processing, and the same image as before processing was reproduced.
Similarly, when a reconstructed liquid crystal display device was produced using the polarizing plates 2 to 4 similarly prepared in Example 7 instead of the polarizing plate 1 and subjected to the above-described test, it was the same before and after the light irradiation treatment. No change in color was observed, and the same image as before light irradiation was reproduced. Further, when a reconstructed liquid crystal display device was produced using the polarizing plate 5 instead of the polarizing plate 1 and the same test was performed, a slight change in color was observed before and after the light irradiation treatment. It was within an acceptable range.

[Comparative Example 3]
A reconstructed liquid crystal display device was produced in the same manner as in Example 9 using the polarizing plate 7 instead of the polarizing plate 1, and the same test as in Example 9 was performed. Was observed, and the display performance of the liquid crystal display device was deteriorated.

[Example 10]
(Creation of polarizing plate with retardation film for VA)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

────────────────────────────────────
Cellulose acetate solution composition ────────────────────────────────────
Cellulose acetate having an acetylation degree of 60.9% 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 318 parts by weight Methanol (No. 2 solvents) 47 parts by mass ─────────────────────────────────────
In another mixing tank, 16 parts by mass of the following retardation increasing agent, 80 parts by mass of methylene chloride and 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution.
A dope was prepared by mixing 474 parts by mass of the cellulose acetate solution with 25 parts by mass of the retardation increasing agent solution and stirring sufficiently. The addition amount of the retardation increasing agent was 3.5 parts by mass with respect to 100 parts by mass of cellulose acetate.

Chemical formula (IV)

The obtained dope was cast using a band casting machine. A film having a residual solvent amount of 15% by mass was horizontally stretched at a stretch ratio of 25% using a tenter under the conditions of 130 ° C. to produce a retardation film (thickness: 80 μm).
About the produced retardation film, an automatic birefringence meter, KOBRA 21ADH (manufactured by Oji Scientific Instruments) was used to measure and calculate the in-plane retardation value and the retardation value in the thickness direction at a wavelength of 550 nm. The in-plane retardation was 40 nm, and the retardation value in the thickness direction was 130 nm.

  The cellulose acylate film 6 and the prepared retardation film were saponified in the same manner as in Example 7. Next, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer. Polyvinyl alcohol (Kuraray PVA-117H) is placed on one side of the polarizer so that the side opposite to the antiglare layer of the cellulose acylate film 6 is adjacent to the polarizer and a retardation film is placed on the other side of the polarizer. A polarizing plate 6A was prepared by bonding a 3% aqueous solution as an adhesive. At this time, it arrange | positioned so that the slow axis of retardation film might become orthogonal to the absorption axis of a polarizing plate.

  The cellulose acylate film 2 and the prepared retardation film were saponified in the same manner as in Example 7. Next, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer. The cellulose acylate film 2 is disposed on one side of the polarizer, the retardation film is disposed on the other surface of the polarizer, and a 3% aqueous solution of polyvinyl alcohol (PVA-117H made by Kuraray) is bonded as an adhesive. Created. At this time, it arrange | positioned so that the slow axis of retardation film might become orthogonal to the absorption axis of a polarizing plate.

(Creation of VA liquid crystal display device)
A pair of polarizing plates and an optical compensation film used in a commercially available liquid crystal display device (VL-1530S manufactured by Fujitsu Limited) using a vertical alignment type liquid crystal cell were peeled off, and only the liquid crystal cell was taken out. A polarizing plate 6A was bonded to the viewing side of the liquid crystal cell so that the antiglare layer was on the outside. The polarizing plate 2A was bonded to the other side of the liquid crystal cell with the retardation film side being the cell side so that the absorption axis of the polarizing plate was orthogonal to the other polarizing plate. The liquid crystal panel thus prepared was reassembled to prepare a liquid crystal display device.
About the prepared liquid crystal display device, the above-mentioned standard daylight xenon light was irradiated with super xenon weather meter SX-75 (manufactured by Suga Test Instruments Co., Ltd.) at an irradiance of 150 W / m ² at 60 ° C. and 50% RH. Irradiated for days. Almost no color change was observed after the treatment, and the same image as before the treatment was reproduced.

Claims (9)

A cellulose acylate film formed by mixing a cellulose acylate film and a cellulose acylate film chip containing an additive that is decomposed by light irradiation and dissolving in a solvent, the cellulose acylate film Xenon light (JIS Z8301 <standard daylight xenon light source>) is irradiated at an irradiance of 150 W / m ² for 10 days in an atmosphere of 60 ° C. and 50% RH, and the change in transmittance at 400 nm is 15.0%. A cellulose acylate film characterized in that the change in transmittance at 550 nm is 3.0% or less.   2. The cellulose acylate film according to claim 1, comprising a compound having a wavelength (λmax) giving an absorption maximum of an ultraviolet absorption spectrum of 250 nm or more and 380 nm or less.   The cellulose acylate has at least two maximum points of the acyl substitution degree distribution, and the maximum value of the difference in acyl substitution degree of any two of the plurality of maximum points is 0.15 or less. The cellulose acylate film according to claim 1 or 2.   The cellulose acylate film according to claim 1, wherein at least one layer selected from a hard coat layer, an antireflection layer, and an antiglare layer is provided on at least one surface.   A polarizing plate, wherein the protective film provided on at least one side of the polarizing plate is the cellulose acylate film according to claim 1.   A liquid crystal display device using at least one polarizing plate according to claim 5.   A liquid crystal display device comprising a cellulose acylate film containing an additive that is decomposed by light irradiation on the viewing side of the liquid crystal display device.   A cellulose acylate film formed by mixing a cellulose acylate film chip and a cellulose acylate film chip containing an additive that decomposes upon irradiation with light and dissolving in a solvent was used on the viewing side of the liquid crystal display device. The liquid crystal display device according to claim 7. The liquid crystal display device according to claim 6, wherein the liquid crystal cell is in an IPS mode or a VA mode.