JP2005325301A - Cellulose acylate dope composition and cellulose acylate film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film that has a high dimension stability and retardation stability against the change in humidity, and an optical film and liquid crystal display device using the film. <P>SOLUTION: A cellulose acylate film is manufactured by a casting method comprising a casting step for casting a cellulose acylate dope composition comprising a (meth)acrylate monomer represented by general formula (I), a photopolymerization initiator, and a cellulose acylate, and a step for light irradiation (in the formula, R is H or CH<SB>3</SB>; m is an integer of 1-20; n is an integer of 2-50; X is a n-valent organic group having a hydrocarbon ring structure; and Y is a single bond or an (m+1) valent connecting group). This cellulose acylate film is used for various optical films and liquid crystal devices. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cellulose acylate dope composition, a cellulose acylate film obtained using the same, an optical film using the film, and a liquid crystal display device.

  Cellulose acylate films are widely used as protective films for polarizing plates for liquid crystal display devices because they have moderate water vapor permeability and are easy to process. However, on the other hand, there is a drawback that the retardation change due to humidity is large. Due to this drawback, when a polarizing plate using a cellulose acylate film is used for a long time, problems such as light leakage occur, and the display quality of the liquid crystal display device is lowered. Accordingly, there is a strong demand for reducing the change in retardation due to the humidity of the cellulose acylate film.

  As means for improving this, a method of adding a highly hydrophobic compound to cellulose acylate has been proposed. Although it is effective to use a low molecular plasticizer as an additive, there are problems such as precipitation on the film surface.

  On the other hand, a method using a polymer compound (hereinafter referred to as polymer) as an additive is conceivable, but there are limited polymers compatible with cellulose acylate, and the intended effect is often not sufficiently obtained. For example, as a polymer having high compatibility with cellulose acylate, a polyester in which a molecular weight distribution having a high content of low molecular weight substances is specified has been proposed (see Patent Document 1), but because the polymer is a low molecular weight body, The characteristics as a polymer could not be fully expressed.

  On the other hand, a photopolymerizable monomer compatible with cellulose acylate and a photopolymerization initiator are uniformly doped, and this dope composition is irradiated with ultraviolet light in the casting process to form a polymer network in the cellulose acylate. There is a technology (see Patent Document 2).

In this technology, an ethylenically unsaturated monomer is used as a photopolymerizable monomer, but it is possible to obtain one that sufficiently satisfies both the crosslinkability, the compatibility with cellulose acylate, and the hydrophobicity improving effect of cellulose acylate. Not. Therefore, it cannot be said that the performance of the polarizing plate using this is sufficient, and further improvement of the film itself has been desired.
Japanese Patent Laid-Open No. 2002-22756 JP 2002-20410 A

  An object of the present invention is to provide a cellulose acylate film having dimensional stability and retardation stability against humidity change, and a cellulose acylate dope composition capable of forming the cellulose acylate film. Moreover, it is providing the optical film and liquid crystal display device which used this cellulose acylate film. Furthermore, an object of the present invention is to provide a liquid crystal display device with high display quality without causing problems such as light leakage by using a cellulose acylate film having a small change in mechanical properties and optical properties due to humidity, for example, as a polarizing plate. Is to provide.

As a result of intensive efforts to solve the above-mentioned problems, the present inventor uses a acrylate monomer represented by the following general formula (I) in the above-described method for forming a polymer network in cellulose acylate, thereby reducing humidity. It has been found that the dimensional stability against changes is dramatically improved. More surprisingly, it has been found that using this technique also dramatically reduces the retardation variation of the cellulose acylate film against changes in humidity. The present invention has been made based on this finding.
That is, the present invention
(1) A cellulose acylate dope composition for forming a cellulose acylate film by a solution casting film forming method, which is a (meth) acrylate monomer represented by the following general formula (I), a photopolymerization initiator, and cellulose Cellulose acylate dope composition characterized by containing acylate,

Wherein R is H or CH ₃ , m is an integer of 1 to 20, n is an integer of 2 to 50, X is an n-valent organic group having a hydrocarbon cyclic skeleton, Y is a single bond or m + 1 valent Each represents a linking group).
(2) The cellulose acylate dope composition according to item (1), wherein, in the general formula (I), X is an organic group having an alicyclic skeleton, and R is CH ₃ .
(3) The cellulose acylate dope composition according to item (1) or (2), wherein X is represented by the following formula (II):

(4) A cellulose acylate film produced through a casting step of casting the cellulose acylate dope composition according to any one of (1) to (3) and a step of light irradiation,
(5) An optical film characterized by using the cellulose acylate film described in (4), and an optical film using the cellulose acylate film described in (6) or (4), or the cellulose acylate film. A liquid crystal display device using a film is provided.

  According to the present invention, it is possible to produce a cellulose acylate film and various optical films with small variations in dimensional stability and retardation due to changes in humidity. This film can be used particularly advantageously for VA (vertically aligned) type and IPS (in-phase switching) type liquid crystal display devices.

  The cellulose acylate film of the present invention is a casting process for casting a cellulose acylate dope composition containing cellulose acylate, a (meth) acrylate monomer represented by the general formula (I), and a photopolymerization initiator. Are produced by a solution casting method comprising a series of steps including a light irradiation step, and these are preferably used for optical films and liquid crystal display devices. Hereinafter, each element matter of the present invention will be described in more detail.

[Cellulose acylate]
First, the cellulose acylate preferably used in the present invention will be described in detail. In the cellulose acylate used in the present invention, the acyl group is preferably an acyl group having 2 to 22 carbon atoms. In the present invention, two or more different types of cellulose acylates may be mixed or separated into layers.
The glucose unit which constitutes cellulose and has β-1,4 bonds has free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups. The degree of acyl substitution means the sum of the ratios of esterification of cellulose for each of the 2-position, 3-position and 6-position (100% esterification has a substitution degree of 1).
In the present invention, the substitution degree of each hydroxyl group at the 2-position, 3-position and 6-position of cellulose is not particularly limited, but the sum of the substitution degrees at the 6-position of cellulose acylate is preferably 0.8 or more, more preferably By setting it to 0.85 or more, particularly preferably 0.90 or more, it is possible to improve the solubility of cellulose acylate, and it becomes possible to produce a good solution particularly in a non-chlorine organic solvent.

  The acyl group of the cellulose acylate used in the present invention may be either an aliphatic acyl group or an aromatic acyl group. When the acyl group of the cellulose acylate of the present invention is an aliphatic acyl group, it preferably has 2 to 22 carbon atoms, more preferably 2 to 8 carbon atoms, and 2 to 4 carbon atoms. Particularly preferred. Examples of the aliphatic acyl group include alkylcarbonyl, alkenylcarbonyl, alkynylcarbonyl and the like. When the acyl group is an aromatic acyl group, it preferably has 6 to 22 carbon atoms, more preferably 6 to 18 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Each of these acyl groups may further have a substituent.

  Examples of preferred acyl groups include acetyl, propionyl, butyryl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, isobutyryl, t-butyryl, cyclohexanecarbonyl, oleoyl, Examples include benzoyl, naphthalenecarbonyl, phthaloyl, cinnamoyl and the like. Of these, acetyl, propionyl, butyryl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are more preferable, and acetyl, propionyl and butyryl are particularly preferable.

  The cellulose acylate used in the present invention may be a mixed ester of two or more acyl groups. Preferred examples include cellulose acetate propionate, cellulose acetate butyrate, cellulose propanoate butyrate, and cellulose acetate propio. Nate butyrate, cellulose acetate hexanoate, cellulose acetate octanoate, cellulose acetate cyclohexanoate, cellulose acetate decanoate, cellulose acetate adamantane carboxylate, cellulose acetate sulfate, cellulose acetate carbamate, cellulose propionate sulfate, cellulose acetate Examples thereof include propionate sulfate and cellulose acetate phthalate. More preferable examples include cellulose acetate propionate, cellulose acetate butyrate, cellulose propanoate butyrate, cellulose acetate hexanoate, and cellulose acetate octanoate. Particularly preferred are cellulose acetate propionate and cellulose acetate butyrate.

  A method for synthesizing cellulose acylate is described in Umeda et al., Wood Chemistry 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acylation method using a carboxylic anhydride-acetic acid-sulfuric acid catalyst. Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of carboxylic acid (which may contain water, sulfuric acid, etc., if necessary), and then an acylating agent mixture is added. Esterification to synthesize completely cellulose acylate (the total degree of acyl substitution at the 2nd, 3rd and 6th positions is approximately 3.00). The acylating agent mixed solution is generally composed of acetic acid or carboxylic acid as a solvent, carboxylic acid anhydride as an esterifying agent, and proton acid as a catalyst (sulfuric acid, perchloric acid, zinc chloride, sulfuryl chloride, phosphoric acid, etc.) Or a Lewis acid. Carboxylic anhydride is preferably used in a stoichiometric excess over the total of the cellulose that reacts with it and the water present in the system. The amount of the catalyst is preferably 0.5 to 25 parts by mass with respect to 100 parts by mass of cellulose.

  The reaction temperature can be arbitrarily selected according to the properties of the desired cellulose acylate, but is preferably -30 ° C to 70 ° C, preferably -20 ° C to 60 ° C, and -10 ° C. It is particularly preferable that the temperature is -50 ° C. The reaction temperature may be changed depending on the stage of the reaction. The reaction temperature can be adjusted by controlling the temperature of the acylating agent mixture or the temperature of the reaction vessel.

After completion of the acylation reaction, water or a neutralizing agent (for example, sodium, potassium, calcium, etc.) is used for hydrolysis of the remaining excess carboxylic anhydride and neutralization of some or all of the esterification catalyst. An aqueous solution of carbonate, acetate, hydroxide or oxide such as magnesium, iron, aluminum or zinc may be added. The obtained cellulose acylate is subjected to saponification and depolymerization (so-called aging) by keeping it at −10 to 90 ° C. in the presence of a small amount of an acid catalyst (generally, an acid catalyst such as remaining sulfuric acid). It is preferable to carry out hydrolysis until the cellulose acylate has a degree of acyl substitution and a degree of polymerization. When the desired cellulose acylate is obtained, the remaining catalyst is completely neutralized with a neutralizing agent as described above, or in water or a suitable organic solvent without neutralization. The cellulose acylate can be obtained by charging the cellulose acylate solution (or adding water or an appropriate organic solvent into the cellulose acylate solution) to precipitate the cellulose acylate and washing it. Stabilizers (for example, carbonates, acetates, hydroxides such as sodium, potassium, calcium, magnesium, iron, aluminum or zinc) for the purpose of decomposing cellulose sulfate as a by-product or neutralizing the remaining acid Or treatment with an aqueous solution of oxide).
The synthesis of cellulose acylate having a high degree of substitution at the 6-position is described in JP-A Nos. 11-5851, 2002-212338, 2002-338601 and the like.

  Other synthetic methods of cellulose acylate include the presence of a base (sodium hydroxide, potassium hydroxide, barium hydroxide, sodium carbonate, pyridine, triethylamine, t-butoxy potassium, sodium methoxide, sodium ethoxide, etc.). , A method of reacting with a carboxylic acid halide, a method using a mixed acid anhydride (such as a mixed anhydride of carboxylic acid / trifluoroacetic acid, a mixed anhydride of carboxylic acid / methanesulfonic acid, etc.) as an acylating agent can be used. This is effective when introducing a large number of acyl groups or acyl groups that are difficult to be subjected to liquid phase acylation using a carboxylic anhydride-acetic acid-sulfuric acid catalyst.

  As a method for obtaining a cellulose mixed acylate, a method of reacting two carboxylic acid anhydrides as an acylating agent by mixing or sequentially adding them, a mixed acid anhydride of two carboxylic acids (for example, acetic acid / propionic acid mixed acid anhydride) Product), mixed acid anhydride (for example, acetic acid / propionic acid mixed acid anhydride) in the reaction system using carboxylic acid and another carboxylic acid anhydride (for example, acetic acid and propionic acid anhydride) as raw materials And a method in which cellulose acylate having a degree of substitution of less than 3 is once synthesized, and a remaining hydroxyl group is further acylated with an acid anhydride or acid halide. .

When the low molecular component is removed from the cellulose acylate, the average molecular weight (degree of polymerization) increases, but the viscosity is 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 using a sulfuric acid catalyst, it is preferable to adjust the sulfuric acid catalyst amount in acylation 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, a cellulose acylate having a preferable molecular weight distribution (uniform molecular weight distribution) can be synthesized.
The raw material cotton and the synthesis method of these cellulose acylates of the present invention are described in detail on pages 7 to 12 of the Japan Institute of Invention and Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). Has been described.

  The polymerization degree of the cellulose acylate preferably used in the present invention is an average polymerization degree of 150 to 700, preferably 180 to 550, more preferably 200 to 400, and particularly preferably a viscosity average polymerization degree of 200 to 350. The average degree of polymerization is determined by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962), molecular weight distribution measurement by gel permeation chromatography (GPC), etc. It can be measured by this method. Further details are described in JP-A-9-95538.

  The cellulose acylate used in the production of the cellulose acylate film of the present invention preferably has a moisture content of 2% by mass or less, more preferably 1% by mass or less, and 0.7% by mass or less. It is particularly preferred that there is. In general, cellulose acylate contains water, and the content is known to be 2.5 to 5% by mass. In the present invention, in order to adjust the water content of the cellulose acylate to a preferable amount, it is preferable to dry the cellulose acylate. The drying method is not particularly limited as long as the desired moisture content can be obtained.

  The cellulose acylate film of the present invention is preferably composed of a cellulose acylate in which the polymer component constituting the film substantially has the above definition. “Substantially” means 55% by mass or more (preferably 70% by mass or more, more preferably 80% by mass or more) of the polymer component. As a raw material for film production, cellulose acylate is preferably in the form of particles or powder. When the cellulose acylate is in the form of particles, 90% by mass or more of the particles used preferably have a particle diameter of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible.

[(Meth) acrylate monomer]
In the present invention, by forming a hydrophobic polymer network uniformly in cellulose acylate, the hydrophobicity of cellulose acylate is improved, and the variation in physical properties with respect to changes in humidity is reduced. Therefore, by using the (meth) acrylate monomer represented by the following general formula (I), which easily forms a polymer network structure uniformly in cellulose acylate, the hydrophobicity of cellulose acylate is improved and the physical properties against humidity change Variation can be reduced.

In the formula, R is H or CH ₃ , m is an integer of 1 to 20, n is an integer of 2 to 50, X is an n-valent organic group having a hydrocarbon cyclic skeleton, Y is a single bond or an m + 1 valent linkage Each group is represented.

R represents H or CH ₃ , and H is preferable for increasing the reactivity. Moreover, m represents the integer of 1-20, 1-10 are preferable, 1-6 are more preferable, and 1-3 are the most preferable. N represents an integer of 2 to 50, preferably 1 to 10, more preferably 1 to 8, and most preferably 2 to 6.

  X is an n-valent organic group, and has a hydrocarbon-based cyclic skeleton with low polarizability in order to increase the hydrophobicity of the compound. In the case of a hydrocarbon-based chain skeleton having the same carbon number, the distance between cross-linking points is increased, and the effect of fixing cellulose acylate is weakened. As a result, the retardation fluctuation of the film obtained using such a monomer becomes large.

Examples of the cyclic hydrocarbon of the hydrocarbon-based cyclic skeleton of X include alicyclic hydrocarbons and aromatic hydrocarbons. Especially, the case where it is an alicyclic hydrocarbon is preferable so that it may mention later.
These rings may be singular and may form an X skeleton, or a plurality of these rings may be bonded to form a skeleton. When a plurality of rings are bonded, the rings may be directly bonded to each other.

When the hydrocarbon-based cyclic skeleton of X is an anisotropic group, the retardation may vary. Therefore, it is preferable that the hydrocarbon-based cyclic skeleton of X is isotropic. In order to make the skeleton isotropic, the polar skeleton is made into a spherical object or an alicyclic skeleton having no polarizability. In particular, X is preferably an organic group having an alicyclic skeleton.
Specific examples of X are given below, but the present invention is not limited thereto.

(In X-1 to 13,-represents a bond.)
Among these, X-2,4,6,7,8,9,10,11,12,13 with small polarizability is preferable, and X-2,4,6,11,12,13 is further more preferable. Furthermore, X-2 which is a highly versatile alicyclic skeleton is most preferable. In a preferred embodiment, in the general formula (I), X is X-2 represented by the above formula (II), and R is CH ₃ .

Y represents a single bond or an m + 1 valent linking group, for example, a single bond or an alkylene group (preferably having a carbon number of 1 to 20, more preferably a carbon number of 1 to 8, such as a trimethylene group (—CH ₂ CH ₂ CH _2- ), a hexamethylene group (—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ —), and the like, and an arylene group (preferably having 6 to 30 carbon atoms, more preferably 6 to 12 carbon atoms). Examples thereof include a phenylene group (—C ₆ H ₄ —), a naphthylene group (—C ₁₀ H ₆ —), and the like, and an oxyalkylene group (preferably having 1 to 20 carbon atoms, more preferably 1 carbon atom). is 12, for example, oxyethylene group _(-OCH 2 _CH 2 -), oxypropylene group _{(-OCH 2 CH 2 CH 2 -} ). the like), polyoxyalkylene (Preferably 1 to 10 carbon atoms, more preferably from 1 to 8 carbon atoms, for example di-oxymethylene group _{(-OCH 2 CH 2 OCH 2 CH} 2 -), tri oxymethylene group _{(-OCH 2} CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ -. that), and the like), oxyarylene group (preferably having 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, for example oxy-phenylene group _{(-OC 6 H} 4 -) , An oxynaphthylene group (—OC ₁₀ H ₆ —), etc.), an oxycarbonyl group (—COO—), an iminocarbonyl group (—CONH—), a ureylene group (—NHCONH—), a hetero atom (oxygen atom, etc.) ) And the following Y1-11 linking groups, but not limited thereto.

(In Y-1 to 11,-represents a bond.)
Among these, a single bond, an alkylene group, an oxyalkylene group, a polyoxyalkylene group, Y1, Y2, and Y3 are preferable, a single bond, an oxyalkylene group, a polyoxyalkylene group, Y2, and Y3 are more preferable, an oxyalkylene group, Most preferred are polyoxyalkylene groups, Y2, Y3.

  In the present invention, it is necessary to make the polymer formed in cellulose acylate hydrophobic in order to improve the hydrophobicity of cellulose acylate. On the other hand, if the hydrophobicity is too high, it becomes incompatible with cellulose acylate, so an upper limit of hydrophobicity is necessary. The hydrophobicity of the polymer is a measure of the hydrophobicity of the original (meth) acrylate monomer. When this property is expressed numerically, the water octanol distribution coefficient (logP) of the (meth) acrylate monomer can be referred to. In the present invention, the logP of the (meth) acrylate monomer is preferably 4.0 to 12.0, more preferably 4.0 to 11.5, and most preferably 4.0 to 11.0.

  logP can actually be measured, but Hansch-Leo fragmentation method (Substituent Constants for Correlation Analysis in Chemistry and Biology: published by John Willey and Sons and Chem. Rev. 1993, 93, 1281), depending on substituent parameters Method (Environ. Toxicol. Chem. 1992, 11, 901), atomic fragmentation (J. Pharm. Sci. 1995, 84, 83), Wrecker's fragmentation (Quant. Struct.-Act. Relat. 1993 12: 152, Krippen fragmentation (J. Chem. Inf. Comput. Sci. 1987 27:21), Biswanadohan fragmentation (J. Chem. Inf. Comput. Sci. 1989, 29, p. 163) by the calculation method such as the Bloteau fragment method (Eur. J. Med. Chem.-Chim. Theor. 1984, 19, p. 71) It is also possible to pile up.

  In the present invention, the (meth) acrylate monomer is preferably a low molecule because it is mixed with cellulose acylate, uniformly dispersed, and then photopolymerized. Specifically, the molecular weight is preferably 2000 or less, more preferably 1500 or less, and most preferably 1000 or less. Further, from the viewpoint of safety in handling, the molecular weight is preferably 300 or more, relatively low in skin irritation, more preferably 350 or more, and most preferably 400 or more.

  In the present invention, two or more (meth) acrylate monomers mentioned above may be combined. Moreover, it can also combine with arbitrary monomers.

  Specific examples of the (meth) acrylate monomer represented by the general formula (I) preferably used in the present invention are shown below, but are not limited thereto.

  If there is a commercially available product, the above exemplified monomer can be used as it is. Below, the synthesis example of a typical (meth) acrylate monomer is shown among said exemplary monomers.

(Synthesis of M-3)

First step: 39.1 g of bisphenol A, 74.5 g of 1-bromohexanol and 63.0 g of potassium carbonate were charged into 80 mL of dimethylformamide and stirred at 80 ° C. for 8 hours. This was separated and extracted with ethyl acetate / brine. The resulting organic layer was washed with deionized water, dried over magnesium sulfate, and filtered. The solution was concentrated under reduced pressure with an evaporator while heating. The obtained oil was purified by column chromatography (developing solvent: ethyl acetate / hexane = 1/2). The obtained component was concentrated under reduced pressure to obtain 46.3 g of Intermediate A white solid.
Second step: 45.9 g of A and 51.0 g of triethylamine were charged in 700 mL of acetonitrile and cooled in an ice bath. 32.4 g of acrylic acid chloride was slowly added dropwise so as to keep the internal temperature at 15 ° C. or lower, and the mixture was stirred at room temperature for 1 hour. This was separated and extracted with ethyl acetate / brine. The resulting organic layer was washed with deionized water, dried over magnesium sulfate, and filtered. This solution was concentrated under reduced pressure using an evaporator. The obtained oil was purified by column chromatography (developing solvent: methylene chloride / hexane = 1/1). The obtained component was concentrated under reduced pressure to obtain 53.6 g of M-3 yellow oil.

(Synthesis of M-6)

  69.5 g of 4,4′-isopropylidene dicyclohexanol (Rikabinol HB: manufactured by Shin Nippon Rika Co., Ltd.) and 88.2 g of triethylamine were charged into 410 mL of dimethylformamide and cooled in an ice bath. 68.0 g of acrylic acid chloride was added dropwise over 2 hours so as to keep the internal temperature at 15 ° C. or lower, and the temperature was returned to room temperature. This was separated and extracted with ethyl acetate / brine. The resulting organic layer was washed with deionized water, dried over magnesium sulfate, and filtered. This solution was concentrated under reduced pressure using an evaporator. The obtained oil was purified by column chromatography (developing solvent: ethyl acetate / hexane = 1/1). When the obtained component was concentrated under reduced pressure, 55.0 g of a yellow oil of M-6 was obtained.

[Photopolymerization initiator]
Next, the photopolymerization initiator used in the cellulose acylate dope composition of the present invention will be described in detail.
The photopolymerization initiator in the present invention is a compound that generates at least radicals when irradiated with light. The photopolymerization initiator used in the present invention preferably has a maximum absorption wavelength of 400 nm or less. Thus, the handling can be performed under a white light by setting the absorption wavelength to the ultraviolet region.

The compound that generates radicals preferably used in the present invention is a compound that generates radicals by light irradiation and initiates and accelerates polymerization of a compound having a polymerizable unsaturated group. A known polymerization initiator or a compound having a bond with a small bond dissociation energy can be appropriately selected and used. Moreover, the compound which generate | occur | produces a radical can be used individually or in combination of 2 or more types.
Examples of the compound that generates radicals include amine compounds (described in Japanese Patent Publication No. 44-20189), organic halogenated compounds, carbonyl compounds, organic peroxide compounds, azo polymerization initiators, metallocene compounds, and hexaarylbiimidazole compounds. , Organic boric acid compounds, disulfone compounds and the like.

  Specific examples of the organic halogenated compounds include Wakabayashi et al., “Bullet. Chem. Soc. Japan” 42, 2924 (1969), US Pat. 3,905,815, Japanese Examined Patent Publication No. 46-4605, Japanese Unexamined Patent Publication No. 62-212401, Japanese Unexamined Patent Publication No. 63-70243, Japanese Unexamined Patent Publication No. 63-298339, MP Hat ( M. P. Hut) "Journal of Heterocyclic Chemistry" "1 (No3), (1970)" and the like, and in particular, an oxazole substituted with a trihalomethyl group Compound: S-triazine compound is mentioned. More preferred are s-triazine derivatives in which at least one mono, di, or trihalogen-substituted methyl group is bonded to the s-triazine ring.

  Examples of other organic halogen compounds include ketones, sulfides, sulfones and nitrogen-containing heterocycles described in paragraphs [0039] to [0048] of JP-A-5-27830.

Examples of the carbonyl compound include, for example, “Latest UV Curing Technology”, pages 60 to 62 (published by Technical Information Association, 1991), paragraph numbers [0015] to [0016] of JP-A-8-134404. And the compounds described in paragraph Nos. [0029] to [0031] of JP-A No. 11-217518, and benzoin compounds such as acetophenone, hydroxyacetophenone, benzophenone, thioxan, benzoin ethyl ether, benzoin isobutyl ether, p -Benzoic acid ester derivatives such as ethyl dimethylaminobenzoate and ethyl p-diethylaminobenzoate, benzyldimethyl ketal, acylphosphine oxide and the like.
As said organic peroxide compound, the compound etc. of the paragraph number [0019] of Unexamined-Japanese-Patent No. 2001-139663 are mentioned, for example.

  Examples of the metallocene compound include JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, JP-A-2-4705, Examples thereof include various titanocene compounds described in Kaihei 5-83588, and iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109.

  Examples of the hexaarylbiimidazole compound include JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. Examples include various compounds described in the specification.

  Examples of the organic borate compounds include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188865, JP-A-9-188686, JP-A-9-188710, 2764769, JP-A-2002-116539, etc., and Kanz, Martin (Rad Tech '98. Proceding April 19-22, 1998, Chicago). Examples of the organic borates to be described are: For example, the compounds described in paragraphs [0022] to [0027] of JP-A-2002-116539 can be mentioned.

  As other organic boron compounds, organic boron such as JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, JP-A-7-306527, JP-A-7-292014, etc. Specific examples include transition metal coordination complexes and the like.

  Examples of the sulfone compound include compounds described in JP-A-5-239015, and examples of the disulfone compound include general formulas (II) and (III) described in JP-A 61-166544. Compounds and the like.

[Fine particles]
In the present invention, fine particles can be added to the cellulose acylate dope composition in order to maintain good scratch resistance and film transportability.
They are conventionally used as matting agents, antiblocking agents, or anti-kissing agents. They are not particularly limited as long as they have the functions described above, but preferred specific examples of these matting agents include inorganic compounds such as silicon-containing compounds, silicon dioxide, titanium oxide, zinc oxide, aluminum oxide, and oxidation. Barium, zirconium oxide, strontium oxide, antimony oxide, tin oxide, tin oxide / antimony, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, etc. More preferred is an inorganic compound containing silicon or zirconium oxide, but silicon dioxide is particularly preferred because the turbidity of the cellulose acylate film can be reduced.
In addition, surface-treated inorganic fine particles are also preferable because of good dispersibility in cellulose acylate. Examples of the treatment method include the method described in JP-A No. 54-57562. Examples of the particles include those described in JP-A No. 2001-151936.
Moreover, as an organic compound, polymers, such as a crosslinked polystyrene, a silicone resin, a fluororesin, and an acrylic resin, are preferable, and a silicone resin is used preferably especially. Among silicone resins, those having a three-dimensional network structure are particularly preferable.

  When these additives are added to the cellulose acylate solution, the method is not particularly limited, and any method can be used as long as a desired cellulose acylate solution can be obtained. For example, an additive may be contained at the stage of mixing cellulose acylate and a solvent, or an additive may be added after preparing a mixed solution with cellulose acylate and a solvent. Furthermore, it may be added and mixed immediately before casting the dope, and it is a so-called immediately preceding addition method, and screw type kneading is installed online and used for the mixing. The mixture of the additive may be added to the additive itself, but it may be dissolved in advance using a solvent or a binder (preferably cellulose acylate) or may be used as a solvent that is dispersed and stabilized in some cases. This is a preferred embodiment.

The primary average particle diameter of these fine particles is preferably 0.001 to 20 μm, more preferably 0.001 to 10 μm, and still more preferably 0.002 to 1 μm, from the viewpoint of keeping haze low. It is particularly preferably 0.005 to 0.5 μm.
The amount of fine particles added to cellulose acylate is preferably 0.01 to 0.3 parts by mass, more preferably 0.05 to 0.2 parts by mass with respect to 100 parts by mass of cellulose acylate.

[Other additives]
In addition to the above fine particles, the cellulose acylate dope composition of the present invention includes various additives (for example, plasticizers, ultraviolet inhibitors (absorbents), deterioration inhibitors, optical agents, and the like) in each preparation step. An anisotropic control agent, a release agent, an infrared absorber, etc.), which may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of UV absorbing materials at 20 ° C. or lower and 20 ° C. or higher, and similarly mixing of a plasticizer is described in, for example, JP-A-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, it is described in Japanese Patent Application Laid-Open No. 2001-151902 and the like, but these are conventionally known techniques. Furthermore, for these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used. It is preferable that the usage-amount of these additives is suitably used in the range of 0.001-20 mass% in all the cellulose acylate film formation compositions.

[Adjustment of cellulose acylate dope]
Next, an organic solvent that dissolves cellulose acylate will be described.
As the solvent to be used, a lower aliphatic hydrocarbon chloride or a lower aliphatic alcohol is generally used. Examples of lower aliphatic hydrocarbon chlorides include methylene chloride. Examples of lower aliphatic alcohols include methanol, ethanol, n-propyl alcohol, isopropyl alcohol and n-butanol. Examples of other solvents include acetone substantially free of halogenated hydrocarbons, ketones having 4 to 12 carbon atoms (for example, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone, and methylcyclohexanone), carbon atoms 3-12 esters (such as ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate and 2-ethoxy-ethyl acetate), alcohols having 1 to 6 carbon atoms (for example, Methanol, ethanol, propanol, isopropanol, 1-butanol, t-butanol, 2-methyl-2-butanol, 2-methoxyethanol, 2-butoxyethanol, etc.), ethers having 3 to 12 carbon atoms (for example, diisopropyl ether, dimethoxy) Methane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole, phenetole, etc.), cyclic hydrocarbons having 5 to 8 carbon atoms (for example, cyclopentane, cyclohexane, cycloheptane, cyclooctane, etc.) Is mentioned.

  Preferably, a mixed solvent of esters, ketones, and alcohols is used as the dope preparation solvent from the viewpoint of the solubility of cellulose acylate. Examples of non-halogen organic solvent systems that do not contain halogenated hydrocarbons such as methylene chloride include, for example, paragraphs [0021] to [0025] of JP-A No. 2002-146043 and JP-A No. 2002-146045. Examples of the solvent system described in paragraphs [0016] to [0021] are given.

  The cellulose acylate dope composition of the present invention is preferably a solution in which 10 to 30% by mass of cellulose acylate is dissolved in an organic solvent, and more preferably a solution in which 15 to 20% by mass is dissolved. preferable. The method for carrying out the cellulose acylate at these concentrations may be carried out so as to obtain a predetermined concentration at the stage of dissolution, or it is prepared as a low-concentration solution (for example, 9 to 14% by mass) and then concentrated as described later. You may adjust to a predetermined high concentration solution by a process. In addition, a cellulose acylate solution having a high concentration may be added to the cellulose acylate solution at a predetermined low concentration by adding various additives, and the cellulose acylate solution concentration of the present invention may be obtained by any method. There is no particular problem if it is implemented.

  Regarding the preparation of the cellulose acylate solution (dope) in the present invention, the dissolution method is not particularly limited, and may be a room temperature dissolution method, a cooling dissolution method or a high temperature dissolution method, and further a combination thereof. With respect to these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-95854 -45950, JP-A-2000-53784, JP-A-11-322946, JP-A-11-322947, JP-A-2-276830, JP-A-2000-273239, JP-A-11-. No. 71463, JP-A No. 04-259511, JP-A No. 2000-273184, JP-A No. 11-323017, JP-A No. 11-302388, etc. describe methods for preparing cellulose acylate solutions. The above-described method for dissolving cellulose acylate in an organic solvent is applicable to the present invention as long as it is within the scope of the present invention. These details are described in detail on pages 22 to 25 in the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society for Inventions), especially for non-chlorine solvent systems. Be implemented in a way that Further, the cellulose acylate dope solution of the present invention is usually subjected to solution concentration and filtration. Similarly, the dope solution of the invention is published in the Technical Report of the Invention Association (Public Technical Number 2001-1745, published on March 15, 2001, Invention Association). It is described in detail on the page. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.

The cellulose acylate solution of the present invention preferably has a viscosity and dynamic storage modulus within the range. For example, 1 mL of a sample solution is a rheometer (CLS 500) using a Steel Cone with a diameter of 4 cm / 2 ° (both manufactured by TA Instruments), and a range of 40 ° C. to −10 ° C. at 2 ° C./min with an Oscillation Step / Temperature Ramp. The static non-Newtonian viscosity n ^* (Pa · sec) at 40 ° C. and the storage elastic modulus G ′ (Pa) at −5 ° C. can be determined. In this case, the measurement is started after the sample solution is kept warm until the liquid temperature becomes constant at the measurement start temperature. In the present invention, the viscosity at 40 ° C. is preferably 1 to 300 Pa · sec, and the dynamic storage elastic modulus at −5 ° C. is preferably 10,000 to 1,000,000 Pa.

The ethylenically unsaturated monomer used in the present invention is added to and dissolved in the cellulose acylate solution prepared as described above. In this case, it is preferable to dissolve the (meth) acrylate monomer in an appropriate solvent.
The (meth) acrylate monomer is preferably used in a proportion of 1 to 50% by mass, more preferably 1 to 30% by mass in the total composition of the cellulose acylate solution (dope solution). Moreover, it is preferable to contain in the ratio of 1-60 mass% with respect to a cellulose acylate, More preferably, it is 3-30 mass%.

  The photopolymerization initiator used in the present invention is preferably added to and dissolved in the cellulose acylate solution at the time after the (meth) acrylate monomer is added. In this case, it is preferable to add the photopolymerization initiator while shielding light. It is preferable that a photoinitiator is contained in the composition of this invention in the ratio of 0.001-20 mass% with respect to a cellulose acylate, More preferably, it is 0.1-10 mass%.

[Method for producing cellulose acylate film]
Next, the manufacturing method of the film using the composition of this invention is described. For the method and equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method and apparatus conventionally used for producing a cellulose triacetate film can be used. Hereinafter, description will be given with reference to the drawings. FIG. 1 is a schematic explanatory view showing an example of a casting film production line for producing a cellulose acylate film by a solution casting film forming method. A dope (cellulose acylate solution) prepared from a dissolving machine (pot) (not shown) is taken out and stored once in a storage pot, and the foam contained in the dope is defoamed for final preparation. The storage tank is preferably a mixing tank (11) having a stirring mechanism. The dope is sent from the dope discharge port to the pressurization casting die (14) through a liquid feed pump (12) such as a pressurization metering gear pump that can feed the metering liquid with high accuracy by the number of rotations. Before sending to a casting die (14), you may pass a filter (13) suitably. Alternatively, the prepared dope may be stored in a storage tank (mixing tank) after passing through a filter and sent to a casting die. The dope is cast evenly on a casting band (15) made of a metal support of a casting part running endlessly from a die (slit) of a pressure die, and the peeling point where the metal support almost goes around. Then, the dry-dried dope film (also called web) is peeled off from the metal support. In the figure, 16 and 17 are rotating drums on the casting part side and the non-casting part side, 18 is a guide roll, and 19 is a peeling roll. Cellulose produced by sandwiching both ends in the width direction of the obtained web with clips, transporting with a tenter while maintaining the width, drying, and then transporting with a roll group of a drying device (drying unit, 22) to finish drying. The acylate film (23) is wound up to a predetermined length by a winder (21). In the figure, 20 is a guide roll. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for silver halide photographic light-sensitive materials and functional protective films for electronic displays, in addition to the solution casting film forming apparatus, an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. In many cases, a coating device is added to the surface processing of the film. Each of these manufacturing processes is described in detail on pages 25 to 30 in the Japan Institute of Invention Disclosure Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). (Including rolling), metal support, drying, peeling, stretching and the like.

  Here, although the space temperature of a casting part is not specifically limited in this invention, It is preferable that they are -50 degreeC-50 degreeC. Furthermore, it is preferable that it is -30 degreeC-40 degreeC. In particular, the cellulose acylate solution cast at a low space temperature can be cooled on the support instantly to increase the gel strength, thereby holding the film containing the organic solvent. Thereby, without evaporating the organic solvent from the cellulose acylate, it can be peeled off from the support in a short time, and high-speed casting can be achieved. The means for cooling the space may be normal air, nitrogen, argon, helium or the like, and is not particularly limited. The humidity in that case is preferably 0 to 70% RH, and more preferably 0 to 50% RH. Moreover, in this invention, the temperature of the support body of the casting part which casts a cellulose acylate solution is -50 degreeC-130 degreeC, Preferably it is -30 degreeC-25 degreeC. In order to keep the casting part at the temperature of the present invention, it may be achieved by introducing a cooled gas into the casting part, or a cooling device may be arranged in the casting part to cool the space. At this time, it is important to take care not to attach water, and it can be carried out by a method such as using dry gas.

In the casting step, one type of cellulose acylate solution may be cast in a single layer, or two or more types of cellulose acylate solutions may be cast simultaneously and / or sequentially.
As a method of co-casting a plurality of cellulose acylate solutions of two or more layers, for example, each of solutions containing cellulose acylate is cast from a plurality of casting ports provided at intervals in the traveling direction of the support. (For example, a method described in JP-A-11-198285), a method for casting a cellulose acylate solution from two casting ports (a method described in JP-A-6-134933), a high viscosity cellulose Examples thereof include a method of wrapping a flow of an acylate solution with a low-viscosity cellulose acylate solution and simultaneously extruding the high- and low-viscosity cellulose acylate solution (a method described in JP-A-56-162617). The present invention is not limited to these.

The obtained film is peeled off from the support (band) and further dried. The drying temperature in the drying step is preferably 40 ° C to 250 ° C, particularly preferably 70 ° C to 180 ° C.
Further, in order to remove the residual solvent, it is preferably dried at 50 ° C. to 160 ° C. In that case, the residual solvent is preferably evaporated by drying with high-temperature air whose temperature is changed successively. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, the time from casting to stripping can be shortened. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, and can be appropriately selected according to the type and combination of the solvents used. The amount of residual solvent in the final finished film is preferably 2% by mass or less, and more preferably 0.4% by mass or less in order to obtain a film having good dimensional stability. The specific method of these drying processes may use, for example, any of the conventionally known methods and apparatuses described in the above-mentioned Technical Report of the Invention Association, and is not particularly limited.

  In the present invention, the light irradiation step may be performed at any place between the casting of the dope and the completion of drying, but the light irradiation is performed particularly when the dope film before the completion of drying is on the support. It is preferable to do. This is because when the organic solvent is present in the web in a moderate amount, the molecules can move easily and the polymerization can proceed smoothly. Any light source may be used as long as it is ultraviolet light, and examples thereof include ultrahigh pressure, high pressure, medium pressure, and low pressure mercury lamps, chemical lamps, carbon arc lamps, metal halide lamps, xenon lamps, and sunlight. Various laser light sources having a wavelength of 350 to 420 nm can be used by employing multi-beam irradiation.

Photopolymerization by ultraviolet irradiation can be performed in air or in an inert gas. However, when using a radically polymerizable compound, the polymerization induction period is shortened or the polymerization rate is sufficiently increased. In addition, it is preferable that the atmosphere has as low an oxygen concentration as possible. The irradiation intensity of the irradiated ultraviolet rays is preferably about 0.1 to 100 mW / cm ² , and the light irradiation amount on the surface of the doped film is preferably 100 to 1000 mJ / cm ² . Further, the temperature distribution of the dope film in the light irradiation step is preferably as uniform as possible, preferably within ± 3 ° C., and more preferably controlled within ± 1.5 ° C. In this range, the polymerization reaction in the in-plane and in-layer depth directions of the dope film proceeds uniformly, which is preferable.

  In the present invention, the cellulose acylate film may be stretched to develop retardation. When stretching, light irradiation is preferably performed after stretching in order not to destroy the structure in the film. Accordingly, stretching is performed in an undried state during film formation (for example, after peeling off from the support after casting until completion of drying), that is, in a state in which an organic solvent is appropriately present in the film. Is preferred. The film thus obtained is dried by the above method.

  The thickness of the film produced according to the present invention is preferably 5 to 500 μm, more preferably 15 to 300 μm, and most preferably 20 to 200 μm. Moreover, when using for an optical film, 20-80 micrometers is also preferable.

The cellulose acylate film can achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a 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 Journal of the Invention Association (Technology No. 2001-1745, issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

  The alkali saponification treatment is also preferably performed by applying a saponification solution. Examples of the coating method include a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, for example, the contents described in JP-A-2002-82226 and W002 / 46809 are exemplified.

  In order to achieve adhesion between the film and the emulsion layer, after surface activation treatment, a functional layer was directly applied on the cellulose acylate film to obtain adhesive force, and some surface treatment was performed once. There is a method in which an undercoat layer (adhesive layer) is provided or a functional layer is applied thereon after or without surface treatment. Details of these subbing layers are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). In addition, various functional layers of the cellulose acylate film of the present invention are described in detail on pages 32 to 45 of the Japan Society for Invention and Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). It is described in.

[Uses of cellulose acylate film]
The use of the cellulose acylate film produced in the present invention will be briefly described first. The cellulose acylate film of the present invention can be used for an optical film such as a retardation film, an optical compensation film, and a polarizing plate protective film. The optical film 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. There is a method in which the obtained cellulose acylate film is treated with an alkali and bonded to both sides of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. 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 to bond the protective film treated surface 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 composed of a polarizer and a protective film that protects both surfaces of the polarizer, and further includes a protective film bonded to one surface of the polarizing plate and a separate film bonded to the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. 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 adhesive 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, a polarizing plate protective film to which the optical film of the present invention is applied can provide excellent display properties regardless of the location. . In particular, since 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, the polarizing plate protective film is particularly preferably used in this portion.

  The cellulose acylate film of the present invention can be used in various applications and is preferable as an optical compensation sheet for liquid crystal display devices. The cellulose acylate 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-Frequential Liquid Nyst) Various display modes such as 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 cellulose acylate film is effective in any display mode liquid crystal display device. Further, it is effective in any of a transmissive, reflective, and transflective liquid crystal display device. The cellulose acylate film of the present invention may be used as a support for an optical compensation sheet of a TN type liquid crystal display device having a TN mode liquid crystal cell. The cellulose acylate film of the present invention may be used as a support for an optical compensation sheet of an STN type liquid crystal display device having an STN mode liquid crystal cell. 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 sheet used in the STN type liquid crystal display device is described in JP-A-2000-105316. The cellulose acylate film of the present invention is particularly advantageously used as a support for an optical compensation sheet of a VA liquid crystal display device having a VA mode liquid crystal cell. The cellulose acylate film of the present invention is also advantageously used as a support for an optical compensation sheet 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.

The cellulose acylate film of the present invention is also advantageously used as an optical compensation sheet for TN-type, STN-type, HAN-type, and GH (Guest-Host) type reflective liquid crystal display devices. 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 sheet used in the reflective liquid crystal display device is described in WO00-65384. The cellulose acylate film of the present invention is also advantageously used as a support for an optical compensation sheet of an ASM type liquid crystal display device having a liquid crystal cell of 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 applications of these cellulose acylate films described above are described in detail in pages 45 to 59 in the Japan Society for Invention and Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). Yes.

  The present invention will be described below in more detail based on examples, but the present invention is not limited thereto.

(Composition of cellulose acylate dope)
The composition in the cellulose acylate dope of each composition example is shown below.
[Composition Example 1]
Cellulose triacetate (CTA: manufactured by Daicel Chemical Industries, Ltd .: acetyl substitution degree 2.8, viscosity average polymerization degree 320) 18.0 parts by mass Monomer: M-1 (manufactured by Sigma-Aldrich) 2.0 parts by mass polymerization initiator: 1- Hydroxycyclohexyl phenyl ketone (IRG184; manufactured by Ciba-Geigy Co., Ltd.) 0.1 parts by mass Fine particles: Silicon dioxide (particle size 20 nm) 0.1 parts by mass UV absorber: 2 (2′-hydroxy-3 ′, 5′-di-tert -Butylphenyl)-
5-chlorobenzotriazole 0.15 parts by mass Methylene chloride 72.0 parts by mass Methanol 8.0 parts by mass

[Composition Example 2]
The monomer of Composition Example 1 was changed to M-1, and the composition was the same as that of Composition Example 1 except that M-3 (synthesized according to the description in this specification) was used.

[Composition Example 3]
The monomer of Composition Example 1 was changed to M-1, and the composition was the same as that of Composition Example 1 except that M-8 (Daiichi Kogyo Seiyaku Co., Ltd .: HBPE-4) was used.

[Composition Example 4]
The composition was the same as that of Composition Example 1 except that the monomer M-1 of Composition Example 1 was M-6 (synthesized according to the description in this specification).

[Composition Example 5]
Composition except that the cellulose triacetate (CTA) of Composition Example 4 is cellulose acetate propionate (CAP: Eastman Chemical Co., Ltd .: acetyl substitution degree 0.8, propionyl substitution degree 2.0, viscosity average polymerization degree 350). The composition was the same as in Example 4.

[Composition Example 6]
Same as Composition Example 4 except that the cellulose triacetate of Composition Example 4 is cellulose acetate butyrate (CAB: Eastman Chemical Co., Ltd .: acetyl substitution degree 1.1, butyryl substitution degree 1.7, viscosity average polymerization degree 300). The composition was as follows.

[Composition Example 7]
The composition was the same as that of Composition Example 1 except that monomer M-1 of Composition Example 1 was dipentaerythritol hexaacrylate (DPHA: manufactured by Sigma-Aldrich).

[Composition Example 8]
The composition was the same as that of Composition Example 1 except that the monomer M-1 of Composition Example 1 was isobornyl acrylate (manufactured by Daicel U-C).

[Composition Example 9]
The composition was the same as that of Composition Example 1 except that the monomer M-1 of Composition Example 1 was 1,9-nonanediol diacrylate (Daiichi Kogyo Seiyaku Co., Ltd.).
The cellulose acylates and monomers of Composition Examples 1 to 9 are summarized in the following table.

  Through the following process, compositions of Composition Examples 1 to 9 were prepared, and films, polarizing plates, and liquid crystal display devices were produced and evaluated.

(Preparation of cellulose acylate dope)
After injecting each solvent mixed solution into a stainless steel dissolution tank having a stirring blade, the cellulose acylate powder was gradually added while stirring well to prepare a dope. After the addition, the mixture was allowed to stand at room temperature (25 ° C.) for 1 hour and then maintained at 35 ° C. to swell the cellulose acylate. To this, a polymerizable monomer dissolved in methylene chloride and methanol, fine particles and an ultraviolet absorber were added. Finally, a polymerization initiator was added to prepare a cellulose acylate dope composition. Next, foam removal was performed by irradiating the dope made of this composition with weak ultrasonic waves. The defoamed dope was first passed through a sintered metal filter having a nominal pore diameter of 5 μm while being pressurized to 1.5 MPa, and then passed through a sintered metal filter of 2.5 μm. The temperature of the dope after filtration was adjusted to 35 ° C. and stored in a stainless steel stock tank. The stock tank had an anchor blade on the center axis and was constantly stirred at a peripheral speed of 0.3 m / sec.

(Preparation of cellulose acylate film)
The dope obtained by the above-described dissolution method was set to 40 ° C., and cast on a mirror surface stainless steel support having a surface temperature of 20 ° C. through a casting Giesser to form a film.
The dope cast on the band was first dried by sending parallel-flow drying air. The overall heat transfer coefficient from the drying air to the dope during drying was 24 kcal / m ² · hr · ° C. The temperature of the drying air was 140 ° C. at the upper part of the band and 100 ° C. at the lower part.
For 5 seconds after casting, the wind was not directly applied to the dope by a wind shielding device, and thereafter, light irradiation was performed using a 2 kW high-pressure mercury lamp under the condition that the total light irradiation amount on the dope surface was 900 mJ / cm ² . Thereafter, a cellulose acylate film having a thickness of 60 μm was produced by conveying a drying zone having a large number of rolls.

(Evaluation of dimensional change of film)
The sample film was conditioned for 24 hours in a room at 25 ° C. and 10% rh, and then cut into a size of 10 cm × 5 cm from an arbitrary part. Each hole in the longitudinal direction was made with a pin gauge, and the dimension (L1) was measured with a pin gauge. Next, humidity was adjusted for 3 hours in a room at 25 ° C. and 80% rh, and the dimension (L2) was measured with a pin gauge. The dimensional change rate was calculated by the following formula.
Dimensional change rate (%) = [(L2-L1) / L1] × 100

(Evaluation of film retardation)
The retardation evaluation of the obtained cellulose acylate film was performed as follows. The Re (retardation) value and Rth (thickness direction retardation) value of the film are defined by the following (I) and (II).
(I): Re = (nx−ny) × d
(II): Rth = {(nx + ny) / 2−nz} × d
In the above (I) and (II), nx is the refractive index in the slow axis direction in the film plane (direction in which the refractive index is maximum), and ny is the fast axis direction in the film plane (the refractive index is minimum). Nz is the refractive index in the thickness direction of the film, and d is the thickness of the film whose unit is nm.

A sample film was cut into a size of 1 cm × 1 cm from an arbitrary portion. After adjusting the humidity to 25 ° C. and 80% rh for 3 hours or more, using an automatic birefringence meter (KOBRA-21ADH / PR: manufactured by Oji Scientific Instruments) at 25 ° C. and 80% rh, The retardation value at a wavelength of 550 nm was measured from the direction inclined by ± 40 ° from the normal direction and the normal to the film surface. It was calculated from the measured values in the in-plane retardation (Re), the vertical direction, and the ± 40 ° direction from the vertical direction. These are designated as Re (80) and Rth (80). Further, these samples were used as they were and measured at 25 ° C. and 10% rh to obtain Re (10) and Rth (10). For each sample, humidity Re change and humidity Rth change were determined according to the following formula.
Humidity Re change = absolute value of difference between Re (80) and Re (10) Humidity Rth change = absolute value of difference between Rth (80) and Rth (10)

(Preparation and evaluation of polarizing plate)
20 parts by weight of water was added to 80 parts by weight of iso-propanol, and KOH was dissolved to 1.5 N, and the temperature was adjusted to 60 ° C. as a saponification solution. At 60 ° C., 10 g / m ^{2 was} applied onto each of the cellulose acylate films formed above, and saponified for 1 minute. Thereafter, using a hot water spray at 50 ° C., spraying was performed for 1 minute at 10 l / m ² · min. According to Example 1 of Japanese Patent Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls and stretched in the longitudinal direction to prepare a polarizing layer having a thickness of 20 μm. Two sheets were selected from the polarizing layer thus obtained and the saponified cellulose acylate film, and the polarizing layer was sandwiched between them, and then a 3% aqueous solution of PVA (PVA-117H manufactured by Kuraray Co., Ltd.) was added. As an adhesive, the polarizing axis and the cellulose acylate film were laminated so that the longitudinal direction was 90 degrees, and a polarizing plate was produced.
The polarizing plate produced as described above was attached to a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261 at 25 ° C. and 60% rh, and then this was applied to 25 ° C. It was brought into 10% rh, and the change in color tone was visually evaluated by a 10-step evaluation (the larger the value, the larger the change). Moreover, the area | region where the display nonuniformity generate | occur | produced was evaluated visually and the ratio (%) where it generate | occur | produced was calculated | required. The obtained results are shown in Table 1.

(Preparation of optical compensation film and its evaluation)
Instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, the saponified cellulose acylate film of the present invention was used, and this was carried out as described in JP-A-2002-62431. After being attached to the bend-aligned liquid crystal cell described in Example 9 at 25 ° C. and 60% rh, this was brought into 25 ° C. and 10% rh, and the change in contrast was visually evaluated. The larger the change, the greater the change. The obtained results are shown in Table 2.

(Evaluation results)
The evaluation results of the cellulose acylate film prepared from each composition, the polarizing plate using the cellulose acylate film, and the optical compensation film are shown below.

As is clear from the above results, the dimensional stability and retardation stability against changes in humidity of the cellulose acylate film in which the monomer represented by the general formula (I) is mixed are good. Furthermore, a polarizing plate and an optical compensation film produced using the same exhibit good performance. Among them, particularly when an acrylate-based ethylenically unsaturated monomer is used, good results are given.
On the other hand, the dimensional stability and retardation stability with respect to humidity change of the cellulose acylate film of the comparative example are lower than those of the present invention, and the performance of the polarizing plate and the optical compensation film produced using the same is higher than that of the present invention. Inferior.
As described above, the cellulose acylate film of the present invention and the polarizing plate and the optical compensation film produced using the same show excellent performance.

It is the schematic of an example of the casting film forming line which enforces the casting film forming method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Mixing tank 12 Liquid feed pump 13 Filter 14 Casting die 15 Casting band 16 Casting side part rotating drum 17 Non-casting part side rotating drum 18 Guide roll 19 Stripping roll 20 Guide roll 21 Winding roll 22 Drying part 23 the film

Claims (6)

A cellulose acylate dope composition for forming a cellulose acylate film by a solution casting film forming method, comprising a (meth) acrylate monomer represented by the following general formula (I), a photopolymerization initiator, and a cellulose acylate A cellulose acylate dope composition comprising:

Wherein R is H or CH ₃ , m is an integer of 1 to 20, n is an integer of 2 to 50, X is an n-valent organic group having a hydrocarbon cyclic skeleton, Y is a single bond or m + 1 valent Each represents a linking group.) The cellulose acylate dope composition according to claim 1, wherein, in the general formula (I), X is an organic group having an alicyclic skeleton, and R is CH ₃ . The cellulose acylate dope composition according to claim 1, wherein X is represented by the following formula (II).

  A cellulose acylate film produced through a casting step of casting the cellulose acylate dope composition according to any one of claims 1 to 3 and a light irradiation step.   An optical film using the cellulose acylate film according to claim 4.   A liquid crystal display device using the cellulose acylate film according to claim 4 or an optical film using the cellulose acylate film.

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