JP2006348269A - Cellulose acylate film, method for producing the same, polarizing plate and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a cellulose acylate film having a small amount of residual solvent and reducing occurrence of display trouble in black displaying when incorporated into a liquid crystal display. <P>SOLUTION: The cellulose acylate film has ≤0.01mass% amount of residual organic solvent, 1.230-1.300g/cm<SP>3</SP>density, 0-20nm in-plane retardation (Re) and 0-70nm retardation (Rth) in the thickness direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cellulose acylate film excellent in optical properties, a method for producing the same, a polarizing plate using the same, and a liquid crystal display device.

  Conventionally, in producing a cellulose acylate film used in a liquid crystal image display device, a cellulose acylate resin is dissolved in a chlorinated organic solvent such as dichloromethane, and this is cast on a substrate and dried. The film casting method for forming a film is mainly carried out. Dichloromethane, which is used as a chlorinated organic solvent, has been conventionally used as a good solvent for cellulose acylate, and has a low boiling point (boiling point: about 40 ° C.) in the film-forming and drying steps of the manufacturing process. It is preferably used. In recent years, from the viewpoint of environmental conservation, the amount of chlorinated organic solvents having a low boiling point has been significantly reduced, such as preventing leakage by handling in a closed facility. Furthermore, even in the unlikely event of leakage, install a gas absorption tower to adsorb the organic solvent before releasing it to the outside air, or disassemble the chlorine-based organic solvent by thermal combustion or electron beam before discharging. As a result, almost no organic solvent was discharged to the outside air. However, further research is needed to achieve complete non-emission of chlorinated organic solvents.

  As such a countermeasure, a film forming method in which cellulose acylate is melted and an organic solvent is not used is disclosed (see Patent Document 1). Such a film-forming method is such that the carbon chain of the ester group of cellulose acylate is lengthened to lower the melting point to facilitate melt film formation. Specifically, melt film formation at a low temperature is enabled by changing cellulose acetate to cellulose propionate, cellulose butyrate, or the like. However, in this method by melt film formation, when a polarizing plate is produced using the melt film formation and incorporated in a liquid crystal display device, a display failure occurs in which a bright spot is generated on the screen when black display is performed. was there. That is, it was found that light leaked from the place where it should originally be black and can only be displayed in gray, and an improvement thereof was desired.

JP 2000-352620 A

  The present invention is a cellulose acylate film with a small amount of residual solvent, and when incorporated in a liquid crystal display device, a cellulose acylate film capable of reducing the occurrence of display failure during black display and a method for producing the same, And it aims at providing the polarizing plate and liquid crystal display device using the same.

The object of the present invention is achieved by the following constitution.
[1] The amount of residual organic solvent is 0.01% by mass or less, the density is 1.230 g / cm ^{2 to} 1.300 g / cm ³ , the in-plane retardation (Re) is 0 to 20 nm, and the thickness A cellulose acylate film having a direction retardation (Rth) of 0 to 70 nm.

[2] The cellulose acylate film according to [1], wherein the acyl group of the cellulose acylate resin satisfies the following formulas (1) to (3).
2.0 ≦ X + Y ≦ 3.0 Formula (1)
0 ≦ X ≦ 2.0 Formula (2)
1.2 ≦ Y ≦ 2.9 Formula (3)
[In formula, X shows the substitution degree of an acetyl group. Y shows the sum total of the substitution degree of a C3-C7 acyl group. ]

[3] A step of kneading and melting the cellulose acylate resin using a biaxial kneading extruder under conditions of 150 ° C. to 220 ° C., screw rotation speed 100 rpm to 800 rpm, and residence time 5 seconds to 3 minutes. The manufacturing method of the cellulose acylate pellet characterized by including.
[4] The method for producing cellulose acylate pellets according to [3], wherein a vent is provided on an outlet side of the biaxial kneading extruder, and the cellulose acylate resin is kneaded and melted while being evacuated. .
[5] The cellulose according to [3] or [4], wherein the cellulose acylate resin is melted and then solidified in a strand shape in warm water at 30 ° C. to 90 ° C., and further cut and dried. A method for producing acylate pellets.

[6] In the method for producing a cellulose acylate film, which includes a step of extruding a melted cellulose acylate resin from a die onto a support to form a film with a predetermined thickness, the cellulose acylate resin is gradually cooled during the film formation. A method for producing a cellulose acylate film, comprising:
[7] A method for producing a cellulose acylate film comprising a step of extruding a melted cellulose acylate resin from a die and then forming a film to a predetermined thickness with a casting drum, the method comprising: A method for producing a cellulose acylate film, wherein the film is formed so that a ratio (T / D) to a film thickness (D) after film formation is 1 to 5.
[8] The method for producing a cellulose acylate film according to [7], wherein the distance between the lip interval of the die and the casting drum is 1% to 20% of the casting width.
[9] The method for producing a cellulose acylate film according to [6] or [8], wherein the temperature at both ends of the die is set to be 1 ° C to 20 ° C higher than the center portion.
[10] The method for producing a cellulose acylate film according to any one of [7] to [9], wherein the temperature of the casting drum is set to (Tg−20) ° C. to (Tg + 20) ° C.
[11] Cellulose acylate pellets produced by the method for producing cellulose acylate pellets according to any one of [3] to [5] are used as the cellulose acylate resin [6] -The manufacturing method of the cellulose acylate film as described in any one of [10].
[12] The method for producing a cellulose acylate film according to any one of [6] to [11], wherein the film is melt-formed using a touch roll.
[13] The cellulose acylate film according to [1] or [2], which is produced by the production method according to any one of [6] to [12].

[14] A polarizing plate comprising a polarizing film and the cellulose acylate film according to any one of [1], [2], and [13] on at least one layer on the polarizing film.
[15] An optical compensation film for a liquid crystal display plate, wherein the cellulose acylate film according to any one of [1], [2] and [13] is used as a substrate.
[16] An antireflection film using the cellulose acylate film according to any one of [1], [2] and [13] as a base material.
[17] A liquid crystal display device using the cellulose acylate film according to any one of [1] [2] [13].

  When the cellulose acylate film of the present invention is incorporated in a liquid crystal display device, it is possible to reduce the occurrence of display failure during black display, and exhibits excellent optical characteristics. Moreover, according to the manufacturing method of this invention, the cellulose acylate film which has such an outstanding optical characteristic can be manufactured simply. Furthermore, the polarizing plate and the liquid crystal display device of the present invention are excellent in display characteristics.

  Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value. In the present invention, “Tg” refers to the glass transition temperature of the cellulose acylate resin or cellulose acylate film unless otherwise specified. Further, in the present invention, the “cellulose acylate resin” means a cellulose acylate before the physical properties of the film specified in the present invention are expressed, and the “cellulose acylate film” is a film formed by means such as melt film formation. It means a cellulose acylate film that expresses the physical properties specified in the invention.

The cellulose acylate film of the present invention has a residual organic solvent amount of 0.01% by mass or less, a density of 1.230 g / cm ^{3 to} 1.300 g / cm ³ , and in-plane retardation (Re). Is 0 to 20 nm, and the thickness direction retardation (Rth) is 0 to 70 nm. Such a cellulose acylate film can be easily produced by the production method of the present invention including a step of extruding a molten cellulose acylate resin from a die onto a support to form a film having a predetermined thickness. The production method of the present invention is characterized in that the cellulose acylate resin is gradually cooled during film formation. The term “slow cooling” as used herein means that the cooling rate during film formation is slower than the normal melt film formation method, and the melt film formation method employing such slow cooling means during film formation is the main method. It is included in the manufacturing method of the invention. Specific slow cooling means can include the following (1-1) to (1-3), and it is preferable to employ at least one of the means in the production method of the present invention. In particular, it is preferable to carry out (1-2) and (1-3) simultaneously.

(1-1) Adjustment of the distance between the lip of the die and the casting drum When the molten cellulose acylate resin is extruded from the die and then formed into a predetermined thickness with the casting drum, the lip of the die and the casting drum The cooling of the cellulose acylate resin can be suppressed by adjusting the distance. In a normal melt film forming method, the distance between the lip of the die and the casting drum is 30% or more of the casting width, but in the present invention, it is preferably 1% to 20%. By setting the distance between the lip and the casting drum to 1 to 20% of the casting width, the lip and the casting drum come into contact with the casting drum with almost no cooling between the lip and the casting drum. And the resulting film density can be reduced. Specifically, the space between the lip of the die and the casting drum is preferably 1% to 20%, more preferably 2% to 15%, and further preferably 3% to 10% of the casting width.

(1-2) Adjustment of the temperature at both ends of the die Both ends of the die are easily cooled by the ambient atmosphere. Therefore, by setting the temperature at both ends of the die higher than the central portion, the state of high molecular motion is maintained, and as a result, the density of the film can be lowered. In the present invention, the temperature at both ends of the die is set higher than the central portion, preferably 1 ° C to 20 ° C, more preferably 2 ° C to 15 ° C, and further preferably 3 ° C to 12 ° C. Such heating of the end of the die can be achieved by adding a panel heater.

(1-3) Adjusting the temperature of the casting drum It is preferable to set the temperature of the casting drum high. By setting the temperature of the casting drum high, the state of high molecular motion is maintained, and as a result, the density of the film can be lowered. In the present invention, the temperature of the casting drum is preferably set to Tg, preferably (Tg ± 20) ° C., more preferably (Tg ± 15) ° C., and further preferably (Tg ± 10) ° C.

By appropriately combining the above conditions, the density is 1.230 g / cm ^{2 to} 1.30.
A cellulose acylate film having a desired value within the range of 0 g / cm ³ , in-plane retardation (Re) of 0 to 20 nm, and thickness direction retardation (Rth) of 0 to 70 nm can be easily prepared. it can. Such a cellulose acylate film cannot be prepared by a conventional melt film-forming method. Further, since the cellulose acylate film of the present invention has a residual solvent amount of 0.01% by mass or less, the residual solvent amount is extremely small as compared with the cellulose acylate film prepared by the conventional solution casting method. It also has features. In particular, the cellulose acylate film of the present invention having a residual sulfate radical amount of 100 ppm or less is characterized by high heat stability, no coloration during melt film formation, and high transparency.
In addition, when it is going to prepare the cellulose acylate film exceeding 1.350 g / cm < ³ > with a melt film forming method, the retardation (Rth) of the thickness direction will be 70 nm or more. If Re exceeds 20 nm or Rth exceeds 70 nm, a display failure in which a bright spot occurs on the screen is not preferable.

Hereinafter, the cellulose acylate film of the present invention and the production method thereof will be described in more detail along the film production procedure.
(Cellulose acylate resin)
The cellulose acylate used in the present invention preferably has an acyl substitution degree satisfying the following formulas (1) to (3). Here, X represents the degree of substitution of acetyl groups, and Y represents the sum of the degree of substitution of acyl groups having 3 to 7 carbon atoms.
2.0 ≦ X + Y ≦ 3.0 Formula (1)
0 ≦ X ≦ 2.0 Formula (2)
1.2 ≦ Y ≦ 2.9 Formula (3)

  Among the acyl groups having 3 to 7 carbon atoms that are the target of the substitution degree Y, propionyl group, butyryl group, 2-methylpropionyl group, pentanoyl group, 3-methylbutyryl group, 2-methylbutyryl group, 2,2 -Dimethylpropionyl (pivaloyl) group, hexanoyl group, 2-methylpentanoyl group, 3-methylpentanoyl group, 4-methylpentanoyl group, 2,2-dimethylbutyryl group, 2,3-dimethylbutyryl group, 3,3-dimethylbutyryl group, cyclopentanecarbonyl group, heptanoyl group, cyclohexanecarbonyl group, benzoyl group and the like can be mentioned, and propionyl group, butyryl group, pentanoyl group, hexanoyl group, benzoyl group are more preferable. Particularly preferably a propionyl group or a butyryl group, and most preferably Mashiku is a propionyl group.

In the cellulose acylate of the present invention, as indicated by the formula (1), X + Y is preferably 2.0 to 3.0. More preferably, it is 2.4-3.0, More preferably, it is 2.5-2.95. If X + Y is 2.0 or more, the hydrophilicity of the cellulose acylate will not increase and the moisture permeability of the film will not become too large.
As shown by the formula (2), X is preferably 0 to 2.0. More preferably, it is 0.05-1.8, More preferably, it is 0.1-1.6.
As shown in the formula (3), Y is preferably 1.2 to 2.9. More preferably, it is 1.3-2.9, More preferably, it is 1.4-2.9, Most preferably, it is 1.5.
~ 2.9.

  The basic principle of these cellulose acylate synthesis methods is described in Mita et al., Wood Chemistry, 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst. Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of acetic acid, and then put into a pre-cooled carboxylated mixed solution to be esterified to complete cellulose acylate (2nd, 3rd and 6th). The total degree of acyl substitution at the position is approximately 3.00). The carboxylated mixed solution generally contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. After completion of the acylation reaction, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used for hydrolysis of excess carboxylic anhydride remaining in the system and neutralization of a part of the esterification catalyst. Of carbonate, acetate or oxide). Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, remaining sulfuric acid) to obtain the desired degree of acyl substitution and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized by using the neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. Cellulose acylate can be obtained by charging the cellulose acylate solution (or adding water or dilute sulfuric acid into the cellulose acylate solution) to separate the cellulose acylate, and washing and stabilizing treatment.

The degree of polymerization of the cellulose acylate preferably used in the present invention is an average degree of polymerization of 100 to 700, preferably 120 to 550, more preferably 120 to 400, and particularly preferably an average degree of polymerization of 130 to 350. The average degree of polymerization is determined by gel permeation chromatography (GPC) as described in Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). ) To measure the molecular weight distribution. Furthermore, the method for measuring the average degree of polymerization is described in detail in JP-A-9-95538.
In the present invention, the weight average degree of polymerization / number average degree of polymerization of cellulose acylate by GPC is preferably 2.0 to 5.0, more preferably 2.2 to 4.5. 4 to 4.0 is particularly preferable.

  By adding a plasticizer to the cellulose acylate of the present invention, the crystal melting temperature (Tm) of the cellulose acylate can be lowered. The molecular weight of the plasticizer used in the present invention is not particularly limited, and may be a low molecular weight or a high molecular weight. Examples of the plasticizer include phosphate esters, alkylphthalylalkyl glycolates, carboxylic acid esters, and fatty acid esters of polyhydric alcohols. These plasticizers may be solid or oily. That is, the melting point and boiling point are not particularly limited. When performing melt film formation, those having non-volatility can be particularly preferably used.

  Specific examples of the phosphate ester include, for example, triphenyl phosphate, tributyl phosphate, tributoxyethyl phosphate, tricresyl phosphate, trioctyl phosphate, trinaphthyl phosphate, trixylyl phosphate, tris ortho-biphenyl phosphate, cresyl phenyl phosphate, Examples include octyl diphenyl phosphate, biphenyl diphenyl phosphate, and 1,4-phenylene tetraphenyl phosphate. Moreover, it is also preferable to use the phosphate ester type plasticizer described in claims 3 to 7 of JP-T-6-501040.

  Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

Examples of carboxylic acid esters include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate and diethyl hexyl phthalate, and citrate esters such as acetyl trimethyl citrate, acetyl triethyl citrate and acetyl tributyl citrate. , Adipates such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisodecyl adipate, bis (butyl diglycol adipate), aromatics such as tetraoctyl pyromellitate, trioctyl trimellitate Polycarboxylic acid esters, dibutyl adipate, dioctyl adipate, dibutyl sebacate, dioctyl sebacate, diethyl azelate Dibutyl azelate, aliphatic, such as dioctyl azelate polycarboxylic acid esters, glycerol triacetate, can be mentioned diglycerol tetraacetate, acetylated glyceride, monoglyceride, a polyhydric alcohol fatty acid esters such as diglyceride. In addition, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin and the like are preferably used alone or in combination.
In addition, aliphatic polyesters composed of glycol and dibasic acid such as polyethylene adipate, polybutylene adipate, polyethylene succinate, polybutylene succinate, aliphatic polyesters composed of oxycarboxylic acid such as polylactic acid, polyglycolic acid, High molecular weight plasticizers such as aliphatic polyesters composed of lactones such as polycaprolactone, polypropiolactone and polyvalerolactone, and vinyl polymers such as polyvinylpyrrolidone. These plasticizers can be used alone or in combination with a low-part plasticizer.

Polyhydric alcohol plasticizers have good compatibility with cellulose fatty acid esters, and glycerin ester compounds such as glycerin esters and diglycerin esters that exhibit a significant thermoplastic effect, and polyalkylene glycols such as polyethylene glycol and polypropylene glycol. And compounds in which an acyl group is bonded to the hydroxyl group of polyalkylene glycol.
Specific glycerin esters include glycerin diacetate stearate, glycerin diacetate palmitate, glycerin diacetate myristate, glycerin diacetate laurate, glycerin diacetate caprate, glycerin diacetate nonanate, glycerin diacetate octanoate, Glycerin diacetate heptanoate, glycerol diacetate hexanoate, glycerol diacetate pentanoate, glycerol diacetate oleate, glycerol acetate dicaprate, glycerol acetate dinonanoate, glycerol acetate dioctanoate, glycerol acetate diheptanoate , Glycerol acetate dicaproate, glycerol acetate divalerate, glycerol acetate dibu Glycerol dipropionate caprate, glycerol dipropionate laurate, glycerol dipropionate myristate, glycerol dipropionate palmitate, glycerol dipropionate stearate, glycerol dipropionate oleate, glycerol tributyrate, glycerol tri Examples include but are not limited to pentanoate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin propionate laurate, glycerin oleate propionate, and these are used alone or in combination. be able to.
Among these, glycerol diacetate caprylate, glycerol diacetate pelargonate, glycerol diacetate caprate, glycerol diacetate laurate, glycerol diacetate myristate, glycerol diacetate palmitate, glycerol diacetate stearate, glycerol diacetate oleate preferable.

Specific examples of diglycerin esters include diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetravalerate, diglycerin tetrahexanoate, diglycerin tetraheptanoate, diglyceride. Glycerin tetracaprylate, diglycerin tetrapelargonate, diglycerin tetracaprate, diglycerin tetralaurate, diglycerin tetramyristate, diglycerin tetrapalmitate, diglycerin triacetate propionate, diglycerin triacetate butyrate, diglycerin Triacetate valerate, diglycerin triacetate hexanoate, diglycerin triacetate heptanoate, diglycerin triacetate caprylate, Glycerin triacetate pelargonate, diglycerol triacetate caprate, diglycerol triacetate laurate, diglycerol triacetate myristate, diglycerol triacetate palmitate, diglycerol triacetate stearate, diglycerol triacetate oleate, diglycerol diacetate dipropionate, diglycerol Diacetate dibutyrate, diglycerol diacetate divalerate, diglycerol diacetate dihexanoate, diglycerol diacetate diheptanoate, diglycerol diacetate dicaprylate, diglycerol diacetate dipelargonate, diglycerol di Acetate dicaprate, diglycerin diacetate dilaurate, diglycerin diacetate dimisti Diglycerin diacetate dipalmitate, diglycerin diacetate distearate, diglycerin diacetate dioleate, diglyceryl acetate tripropionate, diglyceryl acetate tributyrate, diglyceryl acetate trivalerate, diglyceryl acetate tri Hexanoate, diglycerol acetate triheptanoate, diglycerol acetate tricaprylate, diglycerol acetate tripelargonate, diglycerol acetate tricaprate, diglycerol acetate trilaurate, diglycerol acetate trimyristate, diglycerol acetate tri Palmitate, Diglycerol acetate tristearate, Diglycerol acetate trioleate, Diglycerol laurate, Jig Examples include, but are not limited to, mixed acid esters of diglycerin such as glycerin stearate, diglycerin caprylate, diglycerin myristate, and diglycerin oleate, and these can be used alone or in combination.
Among these, diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetracaprylate, and diglycerin tetralaurate are preferable.

  Specific examples of the polyalkylene glycol include polyethylene glycol and polypropylene glycol having an average molecular weight of 200 to 1000, but are not limited thereto, and these can be used alone or in combination.

  Specific examples of the compound in which an acyl group is bonded to the hydroxyl group of polyalkylene glycol include polyoxyethylene acetate, polyoxyethylene propionate, polyoxyethylene butyrate, polyoxyethylene valerate, polyoxyethylene caproate, Polyoxyethylene heptanoate, polyoxyethylene octanoate, polyoxyethylene nonanate, polyoxyethylene caprate, polyoxyethylene laurate, polyoxyethylene myristate, polyoxyethylene palmitate, polyoxyethylene stearate , Polyoxyethylene oleate, polyoxyethylene linoleate, polyoxypropylene acetate, polyoxypropylene propionate, polyoxypropylene butyrate, polyoxypropylene Valerate, polyoxypropylene caproate, polyoxypropylene heptanoate, polyoxypropylene octanoate, polyoxypropylene nonanoate, polyoxypropylene caprate, polyoxypropylene laurate, polyoxypropylene myristate, polyoxy Examples thereof include propylene palmitate, polyoxypropylene stearate, polyoxypropylene oleate, and polyoxypropylene linoleate, but are not limited thereto, and these can be used alone or in combination.

  The addition amount of the plasticizer is preferably 0 to 20% by mass, more preferably 2 to 18% by mass, and most preferably 4 to 15% by mass with respect to the cellulose acylate. When the content of the plasticizer is more than 20% by mass, the heat transferability of the cellulose acylate is improved, but the plasticizer oozes out on the surface of the melt-formed film, and the glass transition temperature Tg is heat resistant. May decrease.

In the present invention, as long as it does not impair the performance required as required, as a stabilizer for preventing thermal deterioration and anti-coloring, phosphite compounds, phosphite compounds, phosphates, thiophosphates, You may add weak organic acid, an epoxy compound, etc. individually or in mixture of 2 or more types. As specific examples of the phosphite stabilizer, compounds described in paragraph numbers [0023] to [0039] of JP-A No. 2004-182979 can be used more preferably. Specific examples of the phosphite ester stabilizer include JP-A No. 51-70316, JP-A No. 10-306175, JP-A No. 57-78431, JP-A No. 54-157159, and JP-A No. 54-157159. The compounds described in JP-A-55-13765 can be used.
The addition amount of the stabilizer in the present invention is preferably 0.005 to 0.5% by mass, more preferably 0.01 to 0.4% by mass or more, and still more preferably 0.05 to cellulose acylate. It is -0.3 mass%. When the addition amount is less than 0.005% by mass, the effect of preventing deterioration and suppressing coloration during melt film formation is insufficient, which is not preferable. On the other hand, when the content is 0.5% by mass or more, the surface of the melt-formed cellulose acylate film oozes out, which is not preferable.
It is also preferable to add a deterioration inhibitor and an antioxidant. By adding a phenol compound, a thioether compound, a phosphorus compound or the like as a deterioration inhibitor or an antioxidant, a synergistic effect appears in deterioration and oxidation prevention. Furthermore, as other stabilizers, the materials described in detail on pages 17 to 22 of the Japan Society for Invention and Technology (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society of Invention) are preferably used. Can do.

  The cellulose ester cellulose acylate of the present invention may contain one or more ultraviolet absorbers. From the viewpoint of preventing deterioration of the liquid crystal, the ultraviolet absorbent for liquid crystal is preferably excellent in the ability to absorb ultraviolet light having a wavelength of 380 nm or less, and has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Examples include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to cellulose ester cellulose acylate is small.

  Preferred UV inhibitors include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol -Bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di tert-butyl-4-hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6 -Tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like.

  In addition, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-tert A phosphorus processing stabilizer such as -butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 3%, more preferably 10 ppm to 2% in terms of mass ratio with respect to cellulose acylate.

  Commercial products may be used as these ultraviolet absorbers. Examples of benzotriazoles include TINUBIN P (Ciba Specialty Chemicals), TINUBIN 234 (Ciba Specialty Chemicals), TINUBIN 320 (Ciba Specialty Chemicals), TINUBIN 326 (Ciba Specialty Chemicals), and TINUBIN 327 ( Ciba Specialty Chemicals), TINUBIN 328 (Ciba Specialty Chemicals), and Sumisorb 340 (Sumitomo Chemical). Further, as benzophenone-based ultraviolet absorbers, Seasorb 100 (Cipro Kasei), Seasorb 101 (Cipro Kasei), Seasorb 101S (Cipro Kasei), Seasorb 102 (Cipro Kasei), Seasorb 103 (Cipro Kasei), Adekas Type LA-51 ( Asahi Denka), Chemisorp 111 (Chemipro Kasei), UVINUL D-49 (BASF) and the like. Examples of oxalic acid anilide UV absorbers include TINUBIN 312 (Ciba Specialty Chemicals) and TINUBIN 315 (Ciba Specialty Chemicals). Further, as a salicylic acid-based ultraviolet absorber, Seesorb 201 (Cipro Kasei) and Seesorb 202 (Cipro Kasei) are marketed, and as a cyanoacrylate-based UV absorber, Seesorb 501 (Cipro Kasei), UVINUL N-539 (BASF). There is.

(Melting film formation)
The cellulose acylate film of the present invention is preferably produced through a film forming step of forming a melted cellulose acylate resin into a predetermined thickness on a support. Specifically, it is preferable to go through steps of drying, kneading extrusion and casting.
(I) Drying In the present invention, it is preferable to use cellulose acylate pelletized by the above-described method as the meltable cellulose acylate resin. Prior to melt film formation, the moisture content in the pellets is preferably 1% or less, more preferably 0.5% or less, and then charged into a hopper of a melt extruder. At this time, the hopper is set to (Tg-50 ° C) to (Tg + 30 ° C), more preferably (Tg-40 ° C) to (Tg + 10 ° C), and further preferably (Tg-30 ° C) to Tg. Thereby, the re-adsorption of moisture in the hopper can be suppressed, and the drying efficiency can be more easily expressed.

(Ii) Kneading and Extruding The kneading and extruding step is a step of melting cellulose acylate (preferably in the form of pellets) while kneading in a melt extruder. In the present invention, kneading and melting are preferably performed at 120 ° C to 250 ° C, more preferably 140 ° C to 220 ° C, and further preferably 150 ° C to 200 ° C. At this time, the melting temperature may be a constant temperature or may be divided into several parts and controlled. A preferable kneading time is 2 minutes to 60 minutes, more preferably 3 minutes to 40 minutes, and particularly preferably 4 minutes to 30 minutes. Further, the kneading extrusion is preferably carried out while filling the inside of the melt extruder with an inert (nitrogen or the like) air flow or using a vented extruder.

(Iii) Casting In the casting process, melted cellulose acylate resin is passed through a gear pump, the pulsation of the extruder is removed, and then filtered with a metal mesh filter or the like. Extrude into a film. Extrusion may be performed in a single layer, or multiple layers may be extruded using a multi-manifold die or a feed block die. At this time, the thickness unevenness in the width direction can be adjusted by adjusting the distance (T) between the lips of the die.

(Touch roll film formation)
In the present invention, it is more preferable to form a film using a touch roll on a casting drum after extrusion from a die after melting. In this method, the melt discharged from the die is sandwiched between a casting drum and a touch roll to be cooled and solidified. By using the touch roll, the fine unevenness formed on the above-described film can be smoothed, and blur in the liquid crystal display device can be reduced.

  Such a touch roll is preferably elastic so as to reduce residual strain generated when the melt from the die is sandwiched between the rolls. In order to give elasticity to the roll, it is necessary to make the outer cylinder thickness of the roll thinner than a normal roll, and the outer wall thickness Z is preferably 0.05 mm to 7.0 mm, more preferably It is 0.2 mm-5.0 mm, More preferably, it is 0.3 mm-2.0 mm. For example, by reducing the thickness of the outer cylinder, an elastic body layer is provided on a metal shaft or an elastic body layer, and the outer cylinder is placed on the elastic body layer, and a liquid medium layer is provided between the elastic body layer and the outer cylinder. The thing which enabled the touch roll film formation by the ultra-thin outer cylinder by satisfy | filling is mentioned. The casting roll or touch roll preferably has a mirror surface, and the arithmetic average height Ra is preferably 100 nm or less, more preferably 50 nm or less, and further preferably 25 nm or less. Specifically, for example, JP-A-11-314263, JP-A-2002-36332, JP-A-11-235747, JP-A-2004-216717, JP-A-2003-145609, and International Publication No. 97/28950. Those listed in the pamphlet can be used.

  Thus, since the touch roll is filled with the fluid inside the thin outer cylinder, when the touch roll is brought into contact with the casting roll, it is elastically deformed into a concave shape by the pressing. Accordingly, since the touch roll and the casting roll are in surface contact, the pressure is dispersed, and a low surface pressure can be achieved. For this reason, the fine unevenness | corrugation of the surface can be corrected, without leaving a residual distortion in the film pinched | interposed between these. The linear pressure of the preferred touch roll is 3 kg / cm to 100 kg / cm, more preferably 5 kg / cm to 80 kg / cm, and still more preferably 7 kg / cm to 60 kg / cm. The linear pressure referred to here is a value obtained by dividing the force applied to the touch roll by the width of the discharge port of the die. If the linear pressure is 3 kg / cm or more, a fine unevenness reduction effect can be easily obtained by appropriate pressing of the touch roll. In addition, if the linear pressure is 100 kg / cm or less, it is possible to uniformly touch the entire casting roll, and therefore it is easy to reduce fine irregularities over the entire width.

  The temperature of the touch roll is preferably set to 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and further preferably 80 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas inside the roll.

  When extruding a melt-extruded film onto a casting drum, electrostatic contact method, air knife method, air chamber method, vacuum nozzle method, touch roll method, etc. are used to increase the adhesion between the cooling drum and the melt-extruded sheet. It is preferable. Such an adhesion improving method may be performed on the entire surface of the melt-extruded sheet or a part thereof.

The surface temperature of the casting drum is preferably set to (Tg ± 20) ° C., more preferably (Tg ± 15) ° C., and further preferably (Tg ± 10) ° C. with respect to Tg of the cellulose acylate resin. preferable.
The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, and still more preferably 20 m / min to 70 m / min.

The film forming width of the cellulose acylate resin film is preferably 1 m to 5 m, more preferably 1.2 m to 4 m, and particularly preferably 1.3 m to 3 m. The thickness of the unstretched film thus obtained is preferably 30 μm to 400 μm, more preferably 40 μm to 300 μm, and particularly preferably 50 μm to 200 μm.
The film thus obtained is preferably trimmed at both ends and wound up. The trimmed portion is pulverized, or after granulation, depolymerization / repolymerization, etc., if necessary, as a raw material for film of the same type or as a raw material for film of a different type It may be reused. Moreover, it is also preferable from a viewpoint of scratch prevention to attach a lami film to at least one surface before winding.

It is preferable that Re and Rth of the unstretched cellulose acylate film of the present invention satisfy the following formula.
0 ≦ Re ≦ 20
0 ≦ Rth ≦ 70
More preferably, 0 ≦ Re ≦ 15
0 ≦ Rth ≦ 70
More preferably, 0 ≦ Re ≦ 10
0 ≦ Rth ≦ 70

  In this specification, the Re retardation value and the Rth retardation value are calculated based on the following. Re and Rth respectively represent in-plane retardation and retardation in the thickness direction at the wavelength λ. Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) by making light of wavelength λ nm incident in the normal direction of the film. Rth is the retardation value measured by making light of wavelength λ nm incident from a direction inclined + 40 ° with respect to the film normal direction with the Re, slow axis (determined by KOBRA 21ADH) as the tilt axis (rotation axis). Measured in three or more directions such as a retardation value measured by making light of wavelength λ nm incident from a direction inclined −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis KOBRA 21ADH is calculated based on the retardation value. At this time, it is necessary to input an assumed value of average refractive index and a film thickness. KOBRA 21ADH calculates nx, ny, and nz in addition to Rth. The average refractive index of 1.48 is used for cellulose acetate, but values of polymer films for typical optical applications other than cellulose acetate include cycloolefin polymer (1.52), polycarbonate (1.59), poly Values such as methyl methacrylate (1.49) and polystyrene (1.59) can be used. As the average refractive index value of other existing polymer materials, a polymer handbook (John Wiley & Sons, Inc.) or a catalog value of a polymer film can be used. In addition, in the case of a material whose average refractive index is unknown, it can be measured using an Abbe refractometer. In this specification, λ refers to 550 ± 5 nm or 590 ± 5 nm unless otherwise specified.

  The cellulose acylate film of the present invention may be used alone, or may be used in combination with a polarizing plate, a liquid crystal layer or a layer with a controlled refractive index (low reflection layer) or a hard layer on these. A coat layer may be provided for use.

(surface treatment)
The cellulose acylate film of the present invention 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 is a treatment for subjecting the film surface to a plasma treatment in the presence of a plasma-excitable gas. The glow discharge treatment may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa), and plasma treatment under atmospheric pressure is also preferable. The plasma-excitable gas refers to a gas that is plasma-excited under the above-described conditions, for example, chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. Etc.
Details of these are described in detail on pages 30 to 32 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). 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 surface treatments, the alkali saponification treatment is particularly preferable, and is extremely effective as the surface treatment of the cellulose acylate film.

The alkali saponification treatment may be immersed in a saponification solution (immersion method) or a saponification solution may be applied (application method). In the case of the immersion method, an aqueous solution having a pH of 10 to 14 such as NaOH or KOH is passed through a bath heated to 20 to 80 ° C. for 0.1 to 10 minutes, and then neutralized, washed with water, and dried. Can be achieved.
In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. 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, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water. Also, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods include the description of the contents described in JP 2002-82226 A and WO 02/46809 pamphlet.

Moreover, it is also preferable to pass through the undercoat process which provides an undercoat layer for adhesion | attachment with a functional layer. This layer may be coated after the surface treatment or may be coated without the surface treatment. The details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention).
These surface treatments and the undercoating step for forming the undercoating layer can be incorporated at the end of the film forming step, can be carried out independently, or can be carried out in the functional layer applying step described later.

(Functional layer added)
The cellulose acylate film of the present invention is combined with the functional layer described in detail on pages 32 to 45 of the Japan Institute of Invention (Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). It is preferable. Among these, application of a polarizing layer (polarizing plate), application of an optical compensation layer (optical compensation sheet for liquid crystal display plate), and application of an antireflection layer (antireflection film) are preferable.

(1) Application of polarizing layer (preparation of polarizing plate)
[Material used]
Currently, a commercially available polarizing layer is generally prepared by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. It is. As the polarizing layer, a coating type polarizing film represented by Optiva Inc. can also be used. Iodine and dichroic dye in the polarizing layer exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, a stilbene dye, a pyrazolone dye, a triphenylmethane dye, a quinoline dye, an oxazine dye, a thiazine dye, or an anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (for example, a sulfo group, an amino group, or a hydroxyl group). Examples of the dichroic dye include compounds described on page 58 of the Japan Society of Invention Disclosure Technique (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention).

  As the binder for the polarizing layer, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913. , Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Moreover, a silane coupling agent can be used as a polymer. The binder is preferably a water-soluble polymer (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol), more preferably gelatin, polyvinyl alcohol, and modified polyvinyl alcohol, and polyvinyl alcohol and Modified polyvinyl alcohol is most preferred. It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different mass average polymerization degrees. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. Furthermore, the mass average polymerization degree of polyvinyl alcohol is preferably 100 to 5,000. The modified polyvinyl alcohol is described in JP-A-8-338913, 9-152509 and 9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

  The thickness of the protective film of the polarizing film is preferably 25 to 350 μm, more preferably 30 to 200, and still more preferably 40 to 120 μm. When the cellulose acylate film of the present invention is used as a protective film for a polarizing film, both an unstretched film and a stretched film can be used. When a plurality of protective films are formed on the polarizing film, the cellulose acylate film of the present invention may be used for all of them, or the cellulose acylate film of the present invention may be used for at least one sheet. In addition, the stretched cellulose acylate film of the present invention can be used not only for showing a protective film function for a polarizing film but also for showing a retardation compensation function.

The obtained polarizing plate preferably has the following configuration. Here, as the unstretched cellulose triacetate film, Fujitac TD80, TD80U, TD80UF manufactured by Fuji Photo Film Co., Ltd. is preferably used.
Polarizing plate A: Unstretched cellulose acylate film / polarizing film / unstretched cellulose triacetate film Polarizing plate B: Unstretched cellulose acylate film / polarizing film / unstretched cellulose acylate film Polarizing plate C: Stretched cellulose acylate film / polarized light Film / Unstretched cellulose triacetate film Polarizing plate D: Stretched cellulose acylate film / polarizing film / Unstretched cellulose acylate film Polarizing plate E: Stretched cellulose acylate film / polarizing film / stretched cellulose acylate film

[Stretching]
The polarizing layer is preferably dyed with iodine or a dichroic dye after stretching the polarizing film (stretching method) or rubbing (rubbing method).
In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. Stretching may be performed in parallel to the MD direction (parallel stretching), or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it can be stretched more uniformly even at high magnification.
A more preferred stretching method is oblique stretching in which the film is stretched with an inclination of 10 ° to 80 ° in the oblique direction.

(A) Parallel stretching method Prior to stretching, it is preferable to swell the PVA film. The degree of swelling is 1.2 to 2.0 times (mass ratio between before swelling and after swelling). Thereafter, it is preferably stretched at a bath temperature of 15 to 50 ° C., especially 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. . Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), but is preferably 1.2 to 3.5 times, more preferably 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. Thereafter, it is preferably dried at 50 ° C. to 90 ° C. to obtain a polarizing layer.

(B) Diagonal stretching method As the oblique stretching method, a method of stretching using a tenter projecting in an oblique direction in an oblique direction described in JP-A-2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. The preferred water content is 5% to 100%, more preferably 10% to 100%.
The temperature during stretching is preferably 40 ° C to 90 ° C, more preferably 50 ° C to 80 ° C. The humidity is preferably 50% to 100% relative humidity, more preferably 70% to 100% relative humidity, and still more preferably 80% to 100% relative humidity. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.
After the end of stretching, the film is preferably dried at 50 to 100 ° C., more preferably 60 to 90 ° C., preferably 0.5 to 10 minutes, more preferably 1 to 5 minutes.
The absorption axis of the polarizing layer thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and still more preferably 45 ° (40 ° to 50 °).

[Lamination]
The saponified cellulose acylate film and a polarizing layer prepared by stretching can be bonded to produce a polarizing plate. The laminating direction is preferably such that the casting axis direction of the cellulose acylate film and the stretching axis direction of the polarizing plate are 45 °.
The bonding adhesive is not particularly limited, and examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm, and particularly preferably 0.05 to 5 μm after drying.
The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% in the light with a wavelength of 590 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light with a wavelength of 590 nm.
Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, lamination is performed so that the slow axis of λ / 4 and the absorption axis of the polarizing plate are 45 °. At this time, λ / 4 is not particularly limited, but more preferably has a wavelength dependency such that the lower the wavelength, the smaller the retardation. Furthermore, it is preferable to use a λ / 4 plate comprising a polarizing layer having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and an optically anisotropic layer made of a liquid crystalline compound.

(2) Application of optical compensation layer (production of optical compensation sheet for liquid crystal display panel)
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the cellulose acylate film, and further provides an optically anisotropic layer. It is formed by doing.

[Alignment film]
An alignment film can be provided on the surface-treated cellulose acylate film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is also possible to produce an optical compensation sheet using the cellulose acylate film of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.
The alignment film may be an organic compound (for example, ω-tricosane) by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodget method (LB film) Acid, dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.
The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, the side chain having a crosslinkable functional group (for example, double bond) is bonded to the main chain, or the liquid crystalline molecules are aligned. It is preferable to introduce a crosslinkable functional group into the side chain.

  As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohols and modified polyvinyl alcohols, poly (N-methylol acrylamide) described in paragraph No. [0022] of JP-A-8-338913, for example. , Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Moreover, a silane coupling agent can be used as a polymer. The polymer is preferably a water-soluble polymer (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol), more preferably gelatin, polyvinyl alcohol, and modified polyvinyl alcohol, and polyvinyl alcohol and modified polyvinyl alcohol. Polyvinyl alcohol is most preferred. It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. The mass average polymerization degree of polyvinyl alcohol is preferably 100 to 5000.

A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group can be determined according to the type of liquid crystal molecule and the required alignment state.
For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Examples include substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy), and the like. Specific examples of these modified polyvinyl alcohol compounds include those described in, for example, paragraph numbers [0022] to [0145] of JP-A No. 2000-155216 and paragraph numbers [0018] to [0022] of JP-A No. 2002-62426. Etc.
When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystal molecules, the polymer of the alignment film is optically anisotropic. The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet for liquid crystal display panel can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in JP-A 2000-155216, paragraph numbers [0080] to [0100]. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.
Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraph numbers [0023] to [0024] of JP-A No. 2002-62426. As the crosslinking agent, an aldehyde having a high reaction activity, particularly glutaraldehyde is preferable.
0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high temperature and high humidity atmosphere for a long time, sufficient durability without reticulation can be obtained.

  The alignment film can be basically formed by applying the polymer as an alignment film forming material and a transparent support containing a crosslinking agent, followed by drying by heating (crosslinking) and rubbing treatment. As described above, the crosslinking reaction can be carried out at any time after coating on the cellulose acylate film of the present invention. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (for example, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optically anisotropic layer reduces remarkably.

The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. The rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, the heat drying is preferably 60 ° C to 100 ° C, particularly preferably 80 ° C to 100 ° C. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.
The alignment film is provided on the cellulose acylate film of the present invention or on the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.

For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.
When industrially implemented, this is achieved by bringing a rotating rubbing roll into contact with the film with the alignment film being transported. However, the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll can Is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used in a liquid crystal display device, 40 to 50 ° is preferable. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.
The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

[Rod-like liquid crystalline molecules]
As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemical Chemistry of the Quarterly Chemical Review Vol. 22, Liquid Crystal Chemistry (1994), and the 142nd Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radical polymerizable unsaturated group or a cationic polymerizable group. Specifically, for example, the polymerizable group described in paragraphs [0064] to [0086] of JP-A No. 2002-62427 can be used. Liquid crystal compounds.

[Disc liquid crystalline molecules]
For discotic liquid crystal molecules, C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  As a discotic liquid crystalline molecule, a compound having liquid crystallinity having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The discotic liquid crystalline molecule is preferably a compound in which a molecule or an assembly of molecules has rotational symmetry and can impart a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. The discotic core and the polymerizable group are preferably compounds that are bonded via a linking group, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] of JP-A No. 2000-155216.
In hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the alignment film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the alignment film. is doing. The angle preferably decreases with increasing distance. Further, the change in angle can be continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the said angle includes the area | region where an angle does not change, it should just increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the alignment film side can be generally adjusted by selecting the discotic liquid crystalline molecules or the material of the alignment film, or by selecting the rubbing treatment method. Further, the major axis (disk surface) direction of the disk-like liquid crystalline molecules on the surface side (air side) is generally adjusted by selecting the kind of additive used together with the disk-like liquid crystalline molecules or the disk-like liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the major axis orientation direction can also be adjusted by selecting liquid crystalline molecules and additives as described above.

[Other compositions of optically anisotropic layer]
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. These are preferably compatible with the liquid crystalline molecules and can change the tilt angle of the liquid crystalline molecules or do not inhibit the alignment.
Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer, and more preferably one that is copolymerizable with the above-mentioned polymerizable group-containing liquid crystal compound. Examples of the polymerizable monomer include those described in paragraphs [0018] to [0020] of JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.
Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specifically, for example, compounds described in JP-A-2001-330725, paragraph numbers [0028] to [0056] can be mentioned.

The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.
Examples of such polymers include cellulose esters. Preferable examples of the cellulose ester include those described in paragraph No. [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and preferably in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to disturb the alignment of the liquid crystal molecules. It is more preferable.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

[Formation of optically anisotropic layer]
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerization initiator described later and optional components on the alignment film.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.
The coating liquid can be applied by a known method (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

[Fixing the alignment state of liquid crystalline molecules]
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. The polymerization reaction is preferably a photopolymerization reaction.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (US Pat. No. 2,448, 828), α-hydrocarbon-substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (US Pat. Nos. 3,046,127 and 2,951). , 758), a combination of triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compound (Japanese Patent Laid-Open No. 60-105667). Publication, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of ^{20mJ / cm 2 ~5000mJ / cm 2} , a range of 100mJ / cm ² ~800mJ / cm ² More preferably. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

It is also preferable to combine this optical compensation film and a polarizing layer. Specifically, the optically anisotropic layer is formed by coating the coating liquid for the optically anisotropic layer as described above on the surface of the polarizing layer. As a result, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing layer can be produced without using a polymer film between the polarizing layer and the optically anisotropic layer. When a polarizing plate including the cellulose acylate film of the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.
The angle of inclination between the polarizing layer and the optical compensation layer is stretched so as to match the angle formed between the transmission axis of the two polarizing layers bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. Is preferred. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted according to the design of the LCD.

[Liquid Crystal Display]
Each liquid crystal mode in which such an optical compensation film is used will be described.
(TN mode liquid crystal display)
The TN mode liquid crystal display device is most frequently used as a color TFT liquid crystal display device, and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

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

(VA mode liquid crystal display device)
The VA mode liquid crystal display device is characterized in that rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. (1) No voltage is applied to the VA mode liquid crystal cell. In addition to a narrowly-defined VA mode liquid crystal cell (described in JP-A-2-176625), which is sometimes aligned substantially vertically and aligned substantially horizontally when a voltage is applied, Liquid crystal cell with multi-domain mode (MVA mode) (SID97, Digest of tech. Papers (Preliminary Collection) 28 (1997) 845), (3) Substantially vertical alignment of rod-like liquid crystalline molecules when no voltage is applied Mode (n-ASM mode) liquid crystal cell (described in Proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) SURVAIVAL mode Liquid crystal cells (announced at LCD International 98).

(IPS mode liquid crystal display)
The IPS mode liquid crystal display device is characterized in that rod-like liquid crystalline molecules are substantially aligned horizontally in the plane when no voltage is applied, and this is switched by changing the alignment direction of the liquid crystal with and without voltage application. Is a feature. Specifically, Japanese Patent Application Laid-Open Nos. 2004-365941, 2004-12731, 2004-215620, 2002-221726, 2002-55341, and 2003-195333. The thing etc. which are described in the gazette etc. can be used.

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

(3) Application of antireflection layer (antireflection film)
The antireflection layer generally comprises a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (ie, a high refractive index layer and a medium refractive index layer). It is provided above.
Colloidal metal by multilayer deposition of transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, sol-gel method of metal compounds such as metal alkoxides Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.
On the other hand, various antireflection layers formed by laminating and applying thin layers in which inorganic particles are dispersed in a matrix have been proposed as antireflection layers with high productivity.
Further, examples of the antireflection layer include an antireflection film comprising an antireflection layer provided with an antiglare property in which the surface of the uppermost layer has a fine uneven shape on the antireflection film formed by coating as described above. It is done.
The cellulose acylate film of the present invention can be applied to any of the above-mentioned methods, but a coating method (coating type) is particularly preferable.

[Layer structure of coating type antireflection film]
The antireflection layer comprising a layer structure of at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the substrate which is a cellulose acylate film in the present invention satisfies the following relational expression. It is designed to have a refractive index.
Relational expression: refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer Transparent support (cellulose acylate film of the present invention) and medium refraction A hard coat layer may be provided between the rate layers. Further, the antireflection layer may comprise a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples of the antireflection film include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. . Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (for example, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.
The haze of the antireflection layer is preferably 5% or less, more preferably 3% or less. The strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400.

[High refractive index layer and medium refractive index layer]
The layer having a high refractive index (high refractive index layer) of the antireflection layer is composed of a curable film containing at least inorganic compound ultrafine particles having a high refractive index having an average particle size of 100 nm or less and a matrix binder.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples of high refractive index inorganic compound ultrafine particles include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc. (Japanese Patent Laid-Open Nos. 11-295503, 11-153703, 2000-9908). ), An anionic compound or an organometallic coupling agent (JP 2001-310432 A, etc.), a core-shell structure with a high refractive index particle as a core (JP 2001-166104 A, etc.), specific dispersion (For example, JP-A-11-153703, US Pat. No. 6,210,858, JP-A-2002-27776069, etc.) and the like.

Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Furthermore, the material forming the matrix includes a polyfunctional compound-containing composition having at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a portion thereof. At least one composition selected from condensate compositions is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. Such a curable film is described in, for example, JP-A-2001-293818.
The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is preferably adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

[Low refractive index layer]
The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.
The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. As a means for greatly improving the scratch resistance, it is effective to impart slipperiness to the surface, and it is possible to apply a thin film layer means including introduction of silicone by a conventionally known silicone compound, introduction of fluorine by a fluorine-containing compound, or the like.
The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.
Examples of the fluorine compound include paragraphs [0018] to [0026] of JP-A-9-222503, paragraphs [0019] to [0030] of JP-A-11-38202, and JP-A-2001-40284. And the compounds described in paragraph numbers [0027] to [0028] of JP-A No. 2000-284102.

The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (for example, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.
In the crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking group or a polymerizable group, the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, or the like is applied simultaneously or after coating. It is preferable to carry out by light irradiation or heating later.
Further, as the low refractive index layer, a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst is also preferable.
Examples of these silane coupling agents include polyfluoroalkyl group-containing silane compounds or partially hydrolyzed condensates thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, and Japanese Patent Laid-Open No. 58-147484). 9-157582, 11-106704, etc.), silyl compounds containing a (poly) perfluoroalkyl ether group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open No. 2000-117902, 2001) -48590 gazette and 2002-53804 gazette etc.) etc. are mentioned.

The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.
When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.

  The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

[Hard coat layer]
The hard coat layer can be provided on the surface of the substrate which is the cellulose acylate film of the present invention in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the base material and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group of the curable compound is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer.
Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and International Publication WO0 / 46617.

The high refractive index layer described above can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.
The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).
The layer thickness of the hard coat layer can be appropriately designed depending on the application. The layer thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

[Forward scattering layer]
When applied to a liquid crystal display device, the forward scattering layer can be provided in order to provide an effect of improving the viewing angle when the viewing angle is inclined in the vertical and horizontal directions. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.
Examples of the forward scattering layer include, for example, Japanese Patent Application Laid-Open No. 11-38208 in which the forward scattering coefficient is specified, Japanese Patent Application Laid-Open No. 2000-199809 in which the relative refractive index of the transparent resin and the fine particles is in a specific range, and a haze value of 40%. The thing as described in Unexamined-Japanese-Patent No. 2002-107512 etc. which were prescribed | regulated as mentioned above is mentioned.

[Other layers]
In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

[Coating method]
Each layer of the antireflection film is formed by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, micro gravure method or extrusion coating method (US Pat. No. 2,681,294). According to the specification, it can be formed by coating.

[Anti-glare function]
The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.
As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently retained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven layer, and these shapes are maintained on the surface uneven layer. A method of providing a low refractive index layer (for example, JP-A-2000-281410, 2000-95893, 2001-100004, 2001-281407, etc.), uppermost layer (antifouling layer) A method of physically transferring an uneven shape onto the surface after coating (for example, as an embossing method, JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401) Wherein) and the like.

[Measuring method]
The measurement method used in the present invention is described below.
(1) Re and Rth measurement After adjusting the sample film to 25 ° C. and 60% relative humidity for 3 hours or more, using an automatic birefringence meter (KOBRA-21ADH / PR: manufactured by Oji Scientific Instruments), 25 At a temperature of 60 ° C. and a relative humidity of 60%, the retardation value at a wavelength of 590 nm is measured from the direction perpendicular to the sample film surface and ± 40 ° from the normal to the film surface. The in-plane retardation (Re) is calculated from the vertical direction, and the thickness direction retardation (Rth) is calculated from the measured value in the ± 40 ° direction from the film surface ray.

(2) Degree of substitution of cellulose acylate The degree of acyl substitution of cellulose acylate is determined according to Carbohydr. Res. Was determined by ¹³ C-NMR according to the method described in 273 (1995) 83-91 (Tezuka et al.).

(3) Density measurement The density of the cellulose acylate was measured with an automatic densimeter (MINIDENS: manufactured by Ipros).

(4) Measurement of glass transition temperature (Tg) Tg of the obtained pellet was measured by the following method, and the results are shown in Table 1.
20 mg of a sample was placed in a DSC measurement pan, heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream, and then cooled to 30 ° C. at −10 ° C./min. Thereafter, the temperature was raised again from 30 ° C. to 250 ° C., and the temperature at which the baseline began to deviate from the low temperature side was defined as the glass transition temperature (Tg). The results are shown in Table 1.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

(1) Pelletization of cellulose acylate Cellulose acylate having the substitution degree and the polymerization degree shown in Table 1 was blown and dried at 120 ° C. for 3 hours to adjust the water content to 0.1% by mass. Residual organic solvent was not detected. To this, the plasticizer described in Table 1 and silicon dioxide part particles (Aerosil R972V) 0.05% by mass, phosphite stabilizer (P-1) 0.20% by mass, 2,4-as UV absorber Bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, 0.8% by mass, as another UV absorber, 2 (2′- Hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole (0.25% by mass) was added, and the mixture was melt-kneaded at 190 ° C. using a twin-screw kneading extruder. The biaxial kneading extruder was provided with a vacuum vent and evacuated (set to 0.3 atm). It was extruded into a strand having a diameter of 3 mm in a water bath and cut into a length of 5 mm.

(2) Melt Film Formation (2-1) Film Formation Method The cellulose acylate pellets prepared by the above method were dried for 3 hours with a vacuum dryer at 100 ° C. This was put into a hopper adjusted to (Tg-10) ° C., and the cellulose acylate was melt extruded at the following temperature using a screw with a compression ratio of 3.0 using a single screw extruder.
Screw temperature pattern: Upstream supply section (180-195 ° C)
Intermediate compression section (200-210 ° C)
Downstream metering section (210-240 ° C)

  Next, the melted cellulose acylate was passed through a gear pump to remove the pulsation of the extruder, filtered through a 3 μm filter, and cast on a cast drum through a die having a central part set at 230 ° C. and the temperatures at both ends set in Table 1. . At this time, the distance between the die lip and the cast drum was 15% of the casting width. Further, a 3 kV electrode was placed at a position 5 cm away from the melt, and electrostatic application treatment was performed for 5 cm at both ends. A cellulose acylate film having a thickness described in Table 1 was obtained by solidifying through three casting drums having a diameter of 60 cm set to the temperatures described in Table 1. After trimming 5 cm at both ends, a thicknessing process (knurling) with a width of 10 mm and a height of 50 μm was applied to both ends, and a sample with a width of 1.5 m, a film forming speed of 30 m / min, and a winding of 2000 m was taken. A cellulose acylate film having no surface irregularities and unevenness and having an excellent surface shape was obtained.

The Re, Rth, and density of the obtained cellulose acylate unstretched film of the present invention were measured and listed in Table 1. Other physical properties were haze of 0.15%, transparency (transparency) of 93.1%, and molecular orientation axis of 0.3 °. The bright spot foreign material has a length of 0.02 mm or less less than 2 pieces / m ² , 0.02 to 0.05 mm is less than 1 piece / m ² , and 0.05 mm or more, and has excellent characteristics for optical applications. I had it.

(2-2) Touch Roll Film Formation For Examples 13, 14, and 15, the touch roll described in Example 1 of JP-A-11-235747 (those described as a double holding roll) is used (however, a thin metal) The outer roll thickness was 3 mm), and touch roll film formation was performed under the conditions shown in Table 1.
In addition, the same touch roll as described in the first embodiment of the pamphlet of International Publication No. 97/28950 is used (the sheet roll is described as a roll) (however, the cooling water used for the metal outer cylinder is from 18 ° C. to 120 ° C.). The oil was changed to oil at 0 ° C.), and the touch roll was performed under the conditions shown in Table 1. In this case, the same results as in Table 1 were obtained.

(3) Production of polarizing plate (3-1) Saponification of cellulose acylate film The cellulose acylate film was saponified by the following immersion saponification method. That is, a 2.5 mol / L NaOH aqueous solution was used as a saponification solution. The temperature was adjusted to 60 ° C., and the cellulose acylate film was immersed for 2 minutes. Then, it was immersed in 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, and washed with water.

(3-2) Production of Polarizing Layer According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls, and the film was stretched in the longitudinal direction to produce a polarizing layer having a thickness of 20 μm.

(3-3) Bonding The polarizing layer obtained in this way, the saponified unstretched and stretched cellulose acylate film, and the saponified Fujitac (unstretched triacetate film) were combined with PVA (PVA manufactured by Kuraray Co., Ltd.). -117H) 3% aqueous solution was used as an adhesive, and bonded in the following combination in the stretching direction of the polarizing film and the film-forming flow direction (longitudinal method) of cellulose acylate.
Polarizing plate A: Unstretched cellulose acylate film / polarizing layer / Fujitack Polarizing plate B: Unstretched cellulose acylate film / polarizing layer / unstretched cellulose
Acylate film

(3-4) Polarization degree measurement After being allowed to stand in an environment of 60 ° C and 90% humidity for 24 hours, measurement and calculation were performed in accordance with the polarization degree measurement method and the transmittance measurement method of the polarizing plate of EIAJ standard ED-2521A.

(3-5) Mounting Evaluation Of two pairs of polarizing plates installed with a liquid crystal layer sandwiched between 26-inch and 40-inch liquid crystal display devices (manufactured by Sharp Corporation) using VA type liquid crystal cells, an observer The polarizing plate on one side was peeled off, and an adhesive was used, and the polarizing plate A or B was attached instead. A liquid crystal display device was prepared by arranging so that the transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were orthogonal to each other. The obtained liquid crystal display device was observed for light leakage and color unevenness generated in a black display state, and in-plane uniformity. The cellulose acylate film of the present invention was very excellent with no color tone change.

(3-6) Preparation of Low Reflective Film According to Example 47, the cellulose acylate film of the present invention was published in accordance with Example 47 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). As a result, good optical performance was obtained.

(3-7) Preparation of Optical Compensation Film A liquid crystal layer was applied to the cellulose acylate film of the present invention according to Example 1 of JP-A-11-316378, and a good optical compensation film was obtained.

  When the cellulose acylate film of the present invention is incorporated in a liquid crystal display device, it is possible to reduce the occurrence of display failure during black display, and exhibits excellent optical characteristics. Moreover, according to the manufacturing method of this invention, the cellulose acylate film which has such an outstanding optical characteristic can be manufactured simply. For this reason, according to the present invention, it is possible to efficiently provide an excellent optical film useful for polarizing plates and liquid crystal display devices, and the industrial applicability of the present invention is high.

Claims (6)

The amount of residual organic solvent is 0.01% by mass or less, the density is 1.230 g / cm ^{3 to} 1.300 g / cm ³ , the in-plane retardation (Re) is 0 to 20 nm, and the letters in the thickness direction A cellulose acylate film having a foundation (Rth) of 0 to 70 nm. The cellulose acylate film according to claim 1, wherein an acyl group of the cellulose acylate resin satisfies the following formulas (1) to (3).
2.0 ≦ X + Y ≦ 3.0 Formula (1)
0 ≦ X ≦ 2.0 Formula (2)
1.2 ≦ Y ≦ 2.9 Formula (3)
[In formula, X shows the substitution degree of an acetyl group. Y shows the sum total of the substitution degree of a C3-C7 acyl group. ]   In the method for producing a cellulose acylate film having a step of forming a film having a predetermined thickness by extruding a molten cellulose acylate resin from a die onto a support, the cellulose acylate resin is gradually cooled during the film formation. A method for producing a cellulose acylate film.   The method for producing a cellulose acylate film according to claim 1, wherein the cellulose acylate film is melt-cast using a touch roll.   A polarizing plate using the cellulose acylate film according to claim 1 or 2 or the cellulose acylate film produced by the production method according to claim 3 or 4 as a protective film of a polarizing film.   A liquid crystal display device using the cellulose acylate film according to claim 1 or the cellulose acylate film produced by the production method according to claim 3 or 4.