JP2008003126A - Polarizing plate, liquid crystal display apparatus and manufacturing method of protection film for polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate and a liquid crystal display apparatus in which front face contrast is increased and display irregularity is improved and to provide the polarizing plate which does not cause failure in an adhering process to a liquid crystal cell. <P>SOLUTION: The polarizing plate is constituted by adhering a protection film onto a liquid crystal cell side of a polarizing film and film thickness of the protection film is 20 to 70μm and amount of curl under 25°C and 60% relative humidity is in a range between -30 mm and +15 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarizing plate and a liquid crystal display device with improved front contrast and improved display unevenness, and further to a polarizing plate and a liquid crystal display device with improved curling when pasted to a liquid crystal cell.

Liquid crystal display devices are widely used in monitors for personal computers and portable devices, and for television applications because of their various advantages, such as low voltage and low power consumption, enabling miniaturization and thinning. Various modes have been proposed for such a liquid crystal display device depending on the alignment state of the liquid crystal molecules in the liquid crystal cell. Conventionally, the liquid crystal display device is in an alignment state twisted by about 90 ° from the lower substrate to the upper substrate of the liquid crystal cell. The TN mode was mainstream.
In general, a liquid crystal display device includes a liquid crystal cell, an optical compensation sheet, and a polarizer. The optical compensation sheet is used for eliminating image coloring or expanding the viewing angle, and a stretched birefringent film or a film obtained by applying a liquid crystal to a transparent film is used. For example, Patent Document 1 discloses a technique for applying an optical compensation sheet in which a discotic liquid crystal is applied on a triacetyl cellulose film, aligned, and fixed to a TN mode liquid crystal cell to widen the viewing angle. However, a television-use liquid crystal display device that is expected to be viewed from various angles on a large screen has a strict requirement for viewing angle dependency, and even with the above-described method, the requirement cannot be satisfied. Therefore, liquid crystal display devices different from the TN mode, such as an IPS (In-Plane Switching) mode, an OCB (Optically Compensatory Bend) mode, and a VA (Vertically Aligned) mode, have been studied. In particular, the VA mode is attracting attention as a liquid crystal display device for TV because of its high contrast and relatively high manufacturing yield.

By the way, the cellulose acylate film is characterized by high optical isotropy (low retardation value) as compared with other polymer films. Therefore, it is common to use a cellulose acylate film for applications requiring optical isotropy, for example, a protective film for a polarizing plate.
On the other hand, the optical compensation sheet (retardation film) of the liquid crystal display device is required to have optical anisotropy (high retardation value). In particular, an optical compensation sheet for VA requires a front retardation (Re) of 30 to 200 nm and a thickness direction retardation (Rth) of 70 to 400 nm. Therefore, it is common to use a synthetic polymer film having a high retardation value such as a polycarbonate film or a polysulfone film as the optical compensation sheet.
As described above, in the technical field of optical materials, when a polymer film requires optical anisotropy (high retardation value), a synthetic polymer film is used and optical isotropy (low retardation value) is used. It was a general rule to use cellulose acylate films when required.

Patent Document 2 proposes a cellulose acetate film having a high retardation value that can be used for applications requiring optical anisotropy, overcoming the conventional general principle. In this proposal, in order to realize a high retardation value with cellulose triacetate, an aromatic compound having at least two aromatic rings is added and subjected to stretching treatment. Cellulose triacetate is generally a polymer material that is difficult to stretch, and it is known that it is difficult to increase the birefringence. To achieve a high retardation value. Since this film can also serve as a protective film for the polarizing plate, there is an advantage that an inexpensive and thin liquid crystal display device can be provided.
Patent Document 3 has an acyl group having 2 to 4 carbon atoms as a substituent, where the substitution degree of acetyl group is A and the substitution degree of propionyl group or butyryl group is B, formula 2.0 ≦ A + B ≦ 3.0 and an optical film containing cellulose ester satisfying the formula A <2.4 at the same time, and the refractive index Nx in the slow axis direction and the refractive index Ny in the fast axis direction at a wavelength of 590 nm are expressed by the formula 0. An optical film characterized by satisfying 0005 ≦ Nx−Ny ≦ 0.0050 is disclosed.
In Patent Document 4, a polarizing plate used in a VA mode liquid crystal display device, the polarizing plate has a polarizer and an optically biaxial mixed fatty acid cellulose ester film, and the liquid crystal cell and the polarizer are interposed. A polarizing plate is disclosed in which the optically biaxial mixed fatty acid cellulose ester film is disposed.
Japanese Patent No. 2587398 European Patent Application 0911656A2 JP 2002-71957 A JP 2003-270442 A

The method disclosed in the above-mentioned document is effective in that an inexpensive and thin liquid crystal display device can be obtained. However, in recent years, liquid crystal display devices have been rapidly increased in contrast, and the mixed fatty acid cellulose ester films described in Patent Documents 3 and 4 have high haze, which lowers the front contrast of the liquid crystal display device. In addition, the mixed fatty acid cellulose ester film described in Patent Documents 3 and 4 is a polarizing plate in which the mixed fatty acid cellulose ester film is used as a protective film having a viewing angle compensation function of a liquid crystal cell. It has become a problem that sticking defects are likely to occur in the attaching process.
Therefore, there is a demand for the development of a polarizing plate having an optical compensation function that does not cause defects in the polarizing plate attaching step to such a liquid crystal cell.
An object of the present invention is to provide a polarizing plate and a liquid crystal display device in which front contrast is improved and display unevenness is improved. Furthermore, it is providing the polarizing plate which does not raise | generate a defect by the bonding process to a liquid crystal cell.

As a result of intensive studies, the present inventors have been able to reduce haze by reducing the thickness of the protective film. As a result, the front contrast of the liquid crystal display device can be improved, and a specific curl amount can be reduced. By setting it as the range, it was found that poor attachment in the polarizing plate attaching step to the liquid crystal cell of the polarizing plate can be suppressed, and the present invention has been completed. Furthermore, the present inventors have found that the curl can be set to a specific range by adjusting the thickness, elastic modulus, and hygroscopic expansion coefficient of the protective film on the cell side and the opposite side of the cell of the polarizing plate.
That is, the present invention is a polarizing plate and a liquid crystal display device having the following constitutions, thereby achieving the object of the present invention.
[1] A polarizing plate in which a protective film A is bonded to at least one of the polarizing films, the protective film A having a thickness of 20 to 70 μm, and a curl amount at 25 ° C. and 60% RH of −30 mm to +15 mm A polarizing plate characterized by being in the range.
[2] The thickness d1 and elastic modulus E1 of the protective film A and the thickness d2 and elastic modulus E2 of the protective film B disposed on the opposite side of the polarizing film satisfy the following formula (III): The polarizing plate according to [1].

  Formula (III): 0.5 × E1 × d1 ≦ E2 × d2 ≦ 1.2 × E1 × d1

[3] Either [1] or [2], wherein the hygroscopic expansion coefficient C1 of the protective film A and the hygroscopic expansion coefficient C2 of the protective film B satisfy the following formula (IV): Polarizing plate.

  Formula (IV): 0.3 × C1 ≦ C2 ≦ 1.3 × C1

[4] The thickness d1, the elastic modulus E1, and the hygroscopic expansion coefficient C1 of the protective film A, and the thickness d2, the elastic modulus E2, and the hygroscopic expansion coefficient C2 of the protective film B disposed on the opposite side of the polarizing film are: The polarizing plate according to any one of [1] to [3], wherein the following formula (V) is satisfied.

  Formula (V): −30 ≦ {(E2 × d2) / (E1 × d1) −1} × 60 + (C2 / C1-1) × 10 ≦ 15

[5] The polarized light according to any one of [1] to [4], wherein Re (λ) and Rth (λ) of the protective film A satisfy the following formulas (VII) and (VIII): Board.

Formula (VII): 20 nm ≦ Re (590) ≦ 200 nm
Formula (VIII): 60 nm ≦ Rth (590) ≦ 400 nm

[In the formula, Re (λ) is a front retardation value (unit: nm) at a wavelength λnm, and Rth (λ) is a retardation value (unit: nm) in a film thickness direction at a wavelength λnm. ]
[6] Any one of [1] to [5], wherein a haze value of at least one of the protective film A and the protective film B is 1.0% or less. Polarizing plate.
[7] The polarizing plate according to any one of [1] to [6], wherein the thickness unevenness of the protective film A is 0.5 μm or less.
[8] The polarizing plate according to any one of [1] to [7], wherein the protective film A has an elastic modulus of 3 to 5 GPa.
[9] The protective film A is a film substantially composed of cellulose acylate obtained by substituting a hydroxyl group of glucose units constituting cellulose with an acyl group having 2 or more carbon atoms, and constitutes cellulose. Assuming that the substitution degree of the hydroxyl group at the 2-position of the glucose unit with the acyl group is DS2, the substitution degree of the hydroxyl group at the 3-position with the acyl group is DS3, and the substitution degree with the acyl group of the hydroxyl group at the 6-position is DS6, The polarizing plate according to any one of [1] to [8], wherein the polarizing plate is formed using cellulose acylate satisfying XI).

  Formula (XI): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0

[10] The polarizing plate according to [9], wherein the protective film A is formed using cellulose acylate satisfying the following formula (XII).

  Formula (XII): DS6 / (DS2 + DS3 + DS6) ≧ 0.315

[11] The polarizing plate according to [9] or [10], wherein the acyl group is an acetyl group.
[12] The protective film A is a cellulose acylate film substantially composed of cellulose acylate which is a mixed fatty acid ester of cellulose in which a hydroxyl group of cellulose is substituted with an acetyl group and an acyl group having 3 or more carbon atoms. And
Substitution degrees DS2A, DS3A, DS6A of acetyl groups at the 2nd, 3rd, 6th positions of the cellulose acylate, and substitution degrees DS2B, DS3B of acyl groups having 3 or more carbon atoms at the 2nd, 3rd, 6th positions. DS6B satisfies the following formula (XIII), and at least one of DS2B, DS3B, and DS6B is formed using cellulose acylate having a positive value, [1] to [11] The polarizing plate in any one of.

  Formula (XIII): 2.0 ≦ DS2A + DS2B + DS3A + DS3B + DS6A + DS6B ≦ 3.0

[13] The polarizing plate according to [12], wherein the acyl group having 3 or more carbon atoms is a butanoyl group.
[14] The polarizing plate according to [12], wherein the acyl group having 3 or more carbon atoms is a propionyl group.
[15] The substitution degree of the acetyl group of the cellulose acylate at the 2nd, 3rd and 6th positions and the substitution degree B of the acyl group having 3 or more carbon atoms satisfy the following formula (XIV): The polarizing plate according to any one of [12] to [14].

  Formula (XIV): (DS6A + DS6B) / (DS2A + DS2B + DS3A + DS3B + DS6A + DS6B) ≧ 0.315

[16] The polarizing plate according to any one of [1] to [15], wherein the protective film A contains at least one retardation enhancer of a rod-shaped compound or a disk-shaped compound.
[17] The above [1] to [16], wherein the protective film A contains at least one selected from a plasticizer, an ultraviolet absorber, a peeling accelerator, a dye, and a matting agent. The polarizing plate in any one of.
[18] A liquid crystal display device comprising a liquid crystal cell and a polarizing plate disposed on at least one of both surfaces of the liquid crystal cell, wherein the polarizing plate is the polarizing plate according to any one of [1] to [17].
[19] The liquid crystal display device according to [18], wherein a polarizing plate is disposed so that the protective film A is on the liquid crystal display device side.
[20] The liquid crystal display device according to any one of [18] or [19], wherein the liquid crystal cell is in a vertical alignment mode.
[21] A method for producing a protective film used in the polarizing plates of [1] to [17], wherein the film is stretched by 30 to 100% in a predetermined X direction and 10 to 60% in a Y direction perpendicular to the X direction. A method for producing a protective film, comprising biaxial stretching at a magnification.
[22] A method for producing a protective film used for the polarizing plate of [1] to [17], wherein stretching in at least one direction of the X direction and the Y direction is biaxial at a stretching speed of 70 to 200% / min. The manufacturing method of the protective film characterized by extending | stretching.
[23] A method for producing a protective film used for the polarizing plate of [1] to [17], wherein a film surface temperature during stretching in at least one direction of the X direction and the Y direction is 130 to 180 ° C. The manufacturing method of the protective film characterized by these.
[24] A method for producing a protective film used in the polarizing plates of [1] to [17], wherein the residual solvent amount at the time of peeling from the support is 50 to 100% by mass. A method for producing a protective film.
[25] A method for producing a protective film used in the polarizing plates of [1] to [17], wherein a residual solvent amount at the end of biaxial stretching in the X direction and the Y direction is 15 to 30% by mass. The manufacturing method of the protective film characterized by these.

The polarizing plate of the present invention has a high front contrast, an excellent viewing angle compensation effect, and improved sticking failure when the polarizing plate is attached to a liquid crystal cell.
Further, by using the polarizing plate of the present invention, it is possible to reduce the loss of the polarizing plate due to poor attachment and the loss of the manufacturing time of the liquid crystal panel due to the redo of the attaching operation of the polarizing plate.

  Hereinafter, the present invention will be described in more detail. In the present specification, when a numerical value represents a physical property value, a characteristic value, etc., the description “(numerical value 1) to (numerical value 2)” means “(numerical value 1) or more and (numerical value 2) or less”. . In the present specification, the description “(meth) acryloyl” means “at least one of acryloyl and methacryloyl”. The same applies to “(meth) acrylate”, “(meth) acrylic acid” and the like.

(Polarizer)
The polarizing plate of the present invention is a polarizing plate in which a protective film is bonded to at least one of the polarizing films, the protective film has a thickness in a specific range, and the polarizing plate is in a specific curl range.
The structure of the polarizing plate of the present invention is illustrated in FIG. 1 includes a polarizer as a polarizing film and two protective films disposed on both sides of the polarizer (TAC1, TAC2, and TAC1 in the figure are liquid crystal cells when used in a liquid crystal display device). And TAC2 is a protective film located on the viewer side), and a functional layer preferably provided outside the TAC2.
And in the polarizing plate of this invention, when it uses for a liquid crystal display device, the film thickness of the said protective film (TAC1) located in the liquid crystal cell side is 20-70 micrometers, Preferably it is 20-60 micrometers. By setting the film thickness to 20 to 70 μm, haze can be reduced and front contrast can be improved. Defects occur, and the yield of the film and the polarizing plate decreases. On the other hand, when it exceeds 70 μm, the haze of the film is high and the front contrast is lowered.

In the polarizing plate of the present invention, the curl amount at 25 ° C. and 60% RH is in the range of −30 mm to +15 mm, preferably in the range of −20 mm to +5 mm, and more preferably in the range of −10 mm to 0 mm.
Attaching a polarizing plate to a liquid crystal cell is generally performed by attaching the polarizing plate to a suction jig with a large number of holes, peeling off the separate film on the surface on which the adhesive has been applied, and placing the adhesive surface on the liquid crystal cell. It is made to stick by making it contact and pressing with a roller. At this time, if the polarizing plate is curled so as to be concave on the liquid crystal cell side, the suction to the suction jig is not sufficiently performed, and the attachment angle to the suction jig is shifted, which causes the sticking to the liquid crystal cell. The attachment angle is shifted and display characteristics as designed cannot be obtained. In addition, the polarizing plate may fall off from the suction jig while being attached to the liquid crystal cell, and the attaching operation cannot be continued, which may interrupt the operation. When the curl amount is within the above range, such a polarizing plate sticking failure does not occur.
Here, the case where it becomes concave on the surface (adhesive coating surface) side to be attached to the liquid crystal cell is called + (plus) curl, and the case where it becomes convex is called-(minus) curl. The curl amount can be controlled by adjusting the relationship between the thickness, elastic modulus, and hygroscopic expansion coefficient of the protective film on the liquid crystal cell side and the protective film on the opposite side of the liquid crystal cell.
The curl is measured by placing a polarizing plate of size 230 mm x 305 mm on a flat table with the side where the end is lifted down and leaving it in an environment of 25 ° C and 60% RH for 2 hours or more. The height of the farthest position at the end of the polarizing plate is measured with reference to the surface, and is defined as the curl amount. A case where the surface is affixed to the liquid crystal cell is concave (+) curl, and a case where the surface is convex is negative (−) curl.
When a separate film and a protective film were attached, the measurement was performed with these films attached.

At least a protective film among a protective film (hereinafter also referred to as protective film A) disposed on the liquid crystal cell side and a protective film (hereinafter also referred to as protective film B) disposed on the side opposite to the liquid crystal cell side. A is preferably a cellulose acylate film.
The cellulose acylate film preferably used as a material for forming the protective film in the present invention will be described. It is preferable to use different cellulose acylates depending on whether the optical anisotropy is increased or decreased.
The cellulose acylate that can be used as a material for forming the protective film A in the present invention is substantially composed of cellulose acylate obtained by substituting the hydroxyl group of the glucose unit constituting cellulose with an acyl group having 2 or more carbon atoms. It is preferable that the film is an automatic film.
Here, “substantially” means 55 mass% or more (preferably 70 mass% or more, more preferably 80 mass% or more) of the polymer component.

(Cellulose acylate for increasing optical anisotropy)
First, the cellulose acylate used in the present invention for increasing the expression of optical anisotropy will be described in detail. In the present invention, two or more different cellulose acylates may be mixed and used.
The cellulose acylate is a mixed fatty acid ester of cellulose obtained by substituting the hydroxyl group of cellulose with an acetyl group and an acyl group having 3 or more carbon atoms, and the degree of substitution of the cellulose with a hydroxyl group is represented by the following formula (XIII ) And (XIV) are preferred.

Formula (XIII): 2.0 ≦ A + B ≦ 3.0
Formula (XIV): 0 <B

Here, A and B represent the substitution degree of the acyl group substituted by the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 or more carbon atoms.
Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The degree of acyl substitution means the proportion of cellulose esterified at each of the 2-position, 3-position and 6-position (100% esterification has a substitution degree of 1).
In the present invention, the total substitution degree (A + B) of hydroxyl groups A and B is 2.0 to 3.0, preferably 2.2 to 2.9, as shown in the above formula (XIII). Yes, particularly preferably 2.40 to 2.85. Further, the substitution degree of B is preferably larger than 0, more preferably 0.6 or more, as shown in the above formula (XIV).
When A + B is less than 2.0, the hydrophilicity becomes strong and it is easy to be affected by environmental humidity.
Further, 28% or more of B is preferably a 6-position hydroxyl group substituent, more preferably 30% or more is a 6-position hydroxyl group substituent, more preferably 31% or more, and particularly preferably 32% or more. A 6-position hydroxyl group substituent is preferred.
Furthermore, the sum of the substitution degrees of A and B at the 6-position of cellulose acylate is preferably 0.75 or more, more preferably 0.80 or more, and particularly preferably 0.85 or more. With these cellulose acylate films, a solution for preparing a film having preferable solubility and filterability can be produced, and a good solution can be produced even in a non-chlorine organic solvent. Furthermore, it is possible to prepare a solution having a low viscosity and good filterability.

  When the cellulose acylate film is the protective film A disposed on the liquid crystal cell side of the polarizing plate, the substitution degree of the hydroxyl group at the 2-position of the glucose unit constituting the cellulose by the acyl group is DS2, and the acyl of the hydroxyl group at the 3-position It is preferable that the following formulas (XI) and (XII) are satisfied, when the substitution degree by the group is DS3 and the substitution degree by the acyl group of the hydroxyl group at the 6-position is DS6.

Formula (XI): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0
Formula (XII): DS6 / (DS2 + DS3 + DS6) ≧ 0.315

By satisfy | filling said formula (XI) and (XII), the solubility to a solvent improves and the humidity dependence of optical anisotropy can be made small.

  In the case where the cellulose acylate film is substantially composed of cellulose acylate which is a mixed fatty acid ester of cellulose in which a hydroxyl group of cellulose is substituted with an acetyl group and an acyl group having 3 or more carbon atoms, The substitution degrees DS2A, DS3A, DS6A of the acetyl groups at the 2nd, 3rd, 6th positions and the substitution degrees DS2B, DS3B, DS6B of the acyl groups with 3 or more carbon atoms at the 2nd, 3rd, 6th positions are as follows: It is preferable that the numerical formula (XIII) is satisfied, and at least one of DS2B, DS3B, and DS6B is a positive value.

  Formula (XIII): 2.0 ≦ DS2A + DS2B + DS3A + DS3B + DS6A + DS6B ≦ 3.0

  Here, the substitution degree of the acetyl group of the cellulose acylate at the 2nd, 3rd and 6th positions and the substitution degree B of the acyl group having 3 or more carbon atoms satisfy the following formula (XIV). preferable.

  Formula (XIV): (DS6A + DS6B) / (DS2A + DS2B + DS3A + DS3B + DS6A + DS6B) ≧ 0.315

  By satisfy | filling said Formula (XIII) or (XIV), the solubility to a solvent improves and the humidity dependence of optical anisotropy can be made small.

  The acyl group (B) having 3 or more carbon atoms may be an aliphatic group or an aromatic hydrocarbon group, and is not particularly limited. For example, cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkyl A carbonyl ester and the like, each of which may further have a substituted group. These preferred B are propionyl, butanoyl, keptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, oleoyl, benzoyl , Naphthylcarbonyl, cinnamoyl group, and the like. Among these, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl group and the like are preferable. Particularly preferred are a propionyl group and a butanoyl group. In the case of a propionyl group, the substitution degree B is preferably 1.3 or more.

  Specific examples of the mixed fatty acid cellulose acylate include cellulose acetate propionate and cellulose acetate butyrate.

(Cellulose acylate for reducing optical anisotropy)
In order to reduce the optical anisotropy, it is preferable that the acyl substitution degree of the hydroxyl group of cellulose is 2.50 to 3.00. Furthermore, the substitution degree is preferably 2.75 to 3.00, and more preferably 2.85 to 3.00.

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

  Among the acyl substituents substituted on the hydroxyl group of the cellulose described above, when it is substantially composed of at least two of an acetyl group, a propionyl group, and a butanoyl group, the cellulose has a total substitution degree of 2.50 to 3.00. The optical anisotropy of the acylate film can be reduced, which is preferable. The degree of acyl substitution is more preferably 2.75 to 3.00, and even more preferably 2.85 to 3.00.

(Method for synthesizing cellulose acylate)
The basic principle of the cellulose acylate synthesis method is described in Mita et al., Wood Chemistry pages 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.
In order to obtain the cellulose acylate, specifically, a cellulose raw material such as cotton linter or wood pulp is pretreated with an appropriate amount of acetic acid, and then esterified by introducing it into a pre-cooled carboxylated mixed solution. Synthesize the rate (the sum of the acyl substitution degree at the 2nd, 3rd and 6th positions 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 esterification 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 with a neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. The cellulose acylate solution is added (or water or dilute sulfuric acid is added to the cellulose acylate solution), the cellulose acylate is separated, washed and stabilized, etc. Can be obtained.

In the cellulose acylate film, it is preferable that the polymer component constituting the film is substantially composed of the specific cellulose acylate. “Substantially” means 55% by mass or more (preferably 70% by mass or more, more preferably 80% by mass or more) of the polymer component.
The cellulose acylate is preferably used in the form of particles. 90% by mass or more of the particles to be used preferably have a particle diameter of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible.
The degree of polymerization of the cellulose acylate preferably used in the present invention is a viscosity average degree of polymerization, preferably 200 to 700, more preferably 250 to 550, still more preferably 250 to 400, and particularly preferably 250 to 350. . The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). Further details are described in JP-A-9-95538.

When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity is lower than that of ordinary cellulose acylate. . Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose acylates. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of cellulose acylate, the water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass or less. In general, cellulose acylate contains water and is known to have a water content of 2.5 to 5% by mass. In order to obtain the water content of the cellulose acylate in the present invention, it is necessary to dry it, and the method is not particularly limited as long as the desired water content is obtained.
The cellulose acylate raw material cotton and the synthesis method thereof are disclosed in JIII Journal of Technical Disclosure No. 2001-1745 (issued March 15, 2001, Invention Association) p. Raw material cotton and synthetic methods described in detail in 7-12 can be employed.

  The cellulose acylate film used in the present invention can be obtained by forming a film using a solution obtained by dissolving the cellulose acylate and, if necessary, an additive in an organic solvent.

(Additive)
Examples of the additive that can be used in the cellulose acylate solution in the present invention include a plasticizer, an ultraviolet absorber, a deterioration preventing agent, a retardation (optical anisotropy) developing agent, and a retardation (optical anisotropy). Examples thereof include a reducing agent, a matting agent (fine particles), a peeling accelerator, and an infrared absorber. In the present invention, it is preferable to use a retardation developer. Moreover, it is preferable to use 1 or more types selected from a plasticizer, an ultraviolet absorber, a peeling accelerator, a dye and a matting agent.
They may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, ultraviolet absorbers of 20 ° C. or lower and 20 ° C. or higher can be mixed and used, and plasticizers can also be mixed and used, for example, as described in JP-A No. 2001-151901.
As the ultraviolet absorber, any type can be selected according to the purpose, and a salicylic acid ester-based, benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based, nickel complex-based absorber or the like is used. Preferred are benzophenone series, benzotriazole series, and salicylic acid ester series. Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2′-di-hydroxy-4,4′-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3- And methacryloxy) propoxybenzophenone. As a benzotriazole ultraviolet absorber, 2 (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2 (2′-hydroxy-5′-tert-butylphenyl) ) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5 Examples include chlorobenzotriazole, 2 (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, and the like. Examples of salicylic acid esters include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate. Among these exemplified ultraviolet absorbers, in particular, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2 (2′-hydroxy-3′-tert-butyl- 5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2 (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) ) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole is particularly preferred.

  As the ultraviolet absorber, it is preferable to use a combination of a plurality of absorbers having different absorption wavelengths because a high blocking effect can be obtained in a wide wavelength range. 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 rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display properties, the absorption of visible light having a wavelength of 400 nm or more is small. Particularly preferred ultraviolet absorbers are the benzotriazole compounds, benzophenone compounds, and salicylic acid ester compounds mentioned above. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose ester is small.

  As for the UV absorber, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-107854. 118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, and JP-A-2000-204173. The described compounds can also be used.

  0.001-5 mass parts is preferable with respect to 100 mass parts of cellulose acylates, and, as for the addition amount of a ultraviolet absorber, 0.01-1 mass part is more preferable. If the addition amount is less than 0.001 part by mass, the effect of addition cannot be sufficiently exhibited. If the addition amount exceeds 5 parts by mass, the ultraviolet absorber may bleed out to the film surface within the above range. Is preferable.

  Further, the ultraviolet absorber may be added simultaneously with the dissolution of cellulose acylate, or may be added to the dope after dissolution. In particular, a mode in which an ultraviolet absorbent solution is added to the dope immediately before casting using a static mixer or the like is preferable because the spectral absorption characteristics can be easily adjusted.

  The deterioration inhibitor can prevent cellulose triacetate and the like from deteriorating and decomposing. Examples of the deterioration preventing agent include butylamine, hindered amine compounds (JP-A-8-325537), guanidine compounds (JP-A-5-271471), benzotriazole-based UV absorbers (JP-A-6-235819), and benzophenone-based compounds. There are compounds such as UV absorbers (JP-A-6-118233).

The plasticizer is preferably a phosphate ester or a carboxylic acid ester. The plasticizer may be triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate (BDP), trioctyl phosphate, tributyl phosphate, dimethyl phthalate (DMP) ), Diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP), diethyl hexyl phthalate (DEHP), triethyl O-acetylcitrate (OACTE), tributyl O-acetylcitrate ( OACTB), acetyl triethyl citrate, acetyl tributyl citrate, butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, tria Chin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, and more preferably one selected from butyl phthalyl butyl glycolate. Furthermore, the plasticizer is preferably (di) pentaerythritol esters, glycerol esters, diglycerol esters. The addition amount of the plasticizer is preferably 1 to 30 parts by mass with respect to 100 parts by mass of cellulose acylate.
When peeling from the support is heavy, it is preferable to use a peeling accelerator. Examples of the peeling accelerator include ethyl esters of citric acid. Further, infrared absorbers are described in, for example, JP-A-2001-194522. The addition amount of the peeling accelerator is preferably 1 part by mass or less with respect to 100 parts by mass of cellulose acylate.
In the present invention, a dye for adjusting the hue may be added. The content of the dye is preferably 10 to 1000 ppm, more preferably 50 to 500 ppm in terms of a mass ratio with respect to cellulose acylate. By containing the dye in this way, light piping of the cellulose acylate film can be reduced, and yellowness can be improved. These compounds may be added together with cellulose acylate and a solvent during the preparation of the cellulose acylate solution, or may be added during or after the solution preparation. Moreover, you may add to the ultraviolet absorber liquid added in-line. The dyes described in JP-A-5-34858 can be used.

These additives may be added at any time in the dope preparation process, but may be added to the final preparation process of the dope preparation process by adding the preparation process. Furthermore, the amount of each material added is not particularly limited as long as the function is exhibited. Moreover, when a cellulose acylate film is a multilayer, the kind and addition amount of the additive of each layer may differ. For example, it is described in Japanese Patent Application Laid-Open No. 2001-151902 and the like, but these are conventionally known techniques. The glass transition point Tg measured with a dynamic viscoelasticity measuring device for cellulose acylate film (Vibron: DVA-225 (ITG Measurement & Control Co., Ltd.)) is determined at 70 to 150 ° C. Furthermore, it is preferable that the elastic modulus measured with a tensile tester (Strograph-R2 (Toyo Seiki)) is 1500 to 4000 MPa. More preferably, the glass transition point Tg is 80 to 135 ° C. and the elastic modulus is 1500 to 3000 MPa. That is, the cellulose acylate film used in the present invention preferably has a glass transition point Tg and an elastic modulus within the above ranges from the viewpoint of process suitability for polarizing plate processing and liquid crystal display device assembly.
Furthermore, regarding the additive, the Japan Society of Invention and Innovation Technical Bulletin No. 2001-1745 (issued March 15, 2001, Japan Society of Invention) p. Those described in detail after 16 can be used as appropriate.

(Retardation expression agent)
In the present invention, it is preferable to use a retardation enhancer in order to greatly develop optical anisotropy and realize a preferable retardation value.
Examples of the retardation enhancer that can be used in the present invention include those composed of rod-like or discotic compounds.
As the rod-like or discotic compound, a compound having at least two aromatic rings can be used.
The addition amount of the retardation developer composed of the rod-like compound is preferably 0.1 to 30 parts by mass, and preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Further preferred.
The discotic retardation enhancer is preferably used in a range of 0.05 to 20 parts by mass, and in a range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. More preferably, it is used in the range of 0.2 to 5 parts by mass, and most preferably in the range of 0.5 to 2 parts by mass.
Since the discotic compound is superior to the rod-like compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required.
Two or more retardation developing agents may be used in combination.
The retardation developer composed of a rod-like or discotic compound preferably has maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable, In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, a compound disclosed in JP 2001-166144 A is preferably used as the discotic compound.

The number of aromatic rings contained in the discotic compound is preferably 2 to 20, more preferably 2 to 12, still more preferably 2 to 8, and most preferably 2 to 6. preferable.
The bond relationship between two aromatic rings can be classified into (a) a condensed ring, (b) a direct bond with a single bond, and (c) a bond through a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Examples of the condensed ring (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thiant It includes emissions ring. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

  The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded with two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The linking group in (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed.
c1: -CO-O-
c2: —CO—NH—
c3: -alkylene-O-
c4: —NH—CO—NH—
c5: —NH—CO—O—
c6: —O—CO—O—
c7: -O-alkylene-O-
c8: -CO-alkenylene-
c9: -CO-alkenylene-NH-
c10: -CO-alkenylene-O-
c11: -alkylene-CO-O-alkylene-O-CO-alkylene-
c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-
c13: -O-CO-alkylene-CO-O-
c14: -NH-CO-alkenylene-
c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent.
Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a non-aromatic heterocyclic group.

The alkyl group preferably has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (eg, hydroxy group, carboxy group, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, and 2- A diethylaminoethyl group is included.
The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.
The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

The aliphatic acyl group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.
The aliphatic acyloxy group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyloxy group include an acetoxy group.
The number of carbon atoms of the alkoxy group is preferably 1 to 8. The alkoxy group may further have a substituent (eg, alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.
The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
The number of carbon atoms of the alkoxycarbonylamino group is preferably 2 to 10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.
The aliphatic amide group preferably has 1 to 10 carbon atoms. Examples of the aliphatic amide group include an acetamide group.
The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group and an n-octanesulfonamido group.
The number of carbon atoms of the aliphatic substituted amino group is preferably 1 to 10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.
The aliphatic substituted carbamoyl group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.
The aliphatic substituted sulfamoyl group preferably has 1 to 8 carbon atoms. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.
The number of carbon atoms in the aliphatic substituted ureido group is preferably 2 to 10. Examples of the aliphatic substituted ureido group include a methylureido group.
Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.
The molecular weight of the retardation developer composed of a discotic compound is preferably 300 to 800.

  In the present invention, in addition to the aforementioned discotic compound, a rod-shaped compound having a linear molecular structure can also be preferably used. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation can be performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited) to determine the molecular structure that minimizes the heat of formation of the compound. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

  As the rod-shaped compound, those having at least two aromatic rings are preferable, and as the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (1) is preferable.

  General formula (1): Ar1-L1-Ar2

In the general formula (1), Ar1 and Ar2 are each independently an aromatic group.
In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.
An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.
As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxyl group, a carboxyl group, a cyano group, an amino group, an alkylamino group (eg, methyl). Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (eg, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-dimethylcarbamoyl group) ), Sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido group, alkylureido group (eg, N -Methylureido group, N, N-dimethylureido group, N, N, N'-trimethylureido group), alkyl group (eg, Methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, cyclopentyl), alkenyl (eg, vinyl, allyl) Group, hexenyl group), alkynyl group (eg, ethynyl group, butynyl group), acyl group (eg, formyl group, acetyl group, butyryl group, hexanoyl group, lauryl group), acyloxy group (eg, acetoxy group, butyryloxy group, Hexanoyloxy group, lauryloxy group), alkoxy group (eg, methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, heptyloxy group, octyloxy group), aryloxy group (eg, phenoxy group), Alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, Ropoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group (eg, phenoxycarbonyl group), alkoxycarbonylamino group (eg, butoxycarbonylamino group, hexyloxycarbonylamino group) , Alkylthio groups (eg, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group), arylthio groups (eg, phenylthio group), alkylsulfonyl groups (eg, methylsulfonyl group, ethylsulfonyl group) , Propylsulfonyl group, butylsulfonyl group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (eg, acetamido group, butyramide group, hexylamide group, Uriruamido group) and a non-aromatic Hajime Tamaki (e.g., morpholyl groups include pyrazinyl group).

Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom, a cyano group, a carboxyl group, a hydroxyl group, an amino group, an alkyl-substituted amino group, an acyl group, an acyloxy group, an amide group, an alkoxycarbonyl group, Alkoxy groups, alkylthio groups and alkyl groups are preferred.
The alkyl part and the alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of alkyl moieties and substituents of alkyl groups include halogen atom, hydroxyl, carboxyl, cyano, amino, alkylamino group, nitro, sulfo, carbamoyl, alkylcarbamoyl group, sulfamoyl, alkylsulfamoyl group, ureido, alkylureido Group, alkenyl group, alkynyl group, acyl group, acyloxy group, acylamino group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, alkylsulfonyl group, amide group And non-aromatic heterocyclic groups. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, hydroxyl, amino, alkylamino group, acyl group, acyloxy group, acylamino group, alkoxycarbonyl group and alkoxy group are preferable.

In the general formula (1), L1 represents an alkylene group, an alkenylene group, an alkynylene group,-
A divalent linking group selected from the group consisting of O-, -CO-, and combinations thereof.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 15, more preferably 1 to 10, still more preferably 1 to 8, and most preferably 1 to 6. It is.

The alkenylene group and alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.
The alkenylene group and alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene or ethynylene).
The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (1), the angle formed by Ar1 and Ar2 across L1 is preferably 140 degrees or more.
As the rod-like compound, a compound represented by the following formula (2) is more preferable.

  Formula (2): Ar1-L2-X-L3-Ar2

  In the general formula (2), Ar1 and Ar2 are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar1 and Ar2 in the general formula (1).

In the general formula (2), L 2 and L 3 are each independently a divalent linking group selected from an alkylene group, —O—, —CO— and a group consisting of a combination thereof.
The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.
The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene or Most preferred is ethylene).
L2 and L3 are particularly preferably —O—CO— or —CO—O—.

In the general formula (2), X is 1,4-cyclohexylene, vinylene or ethynylene.
Specific examples of the compound represented by the general formula (1) or (2) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

  Other preferred compounds are shown below.

Two or more rod-shaped compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.
The rod-like compound can be synthesized by a method described in the literature. References include Mol. Cryst. Liq. Cryst., 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 Page (1989), J. Am. Chem. Soc., 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970), J. Org Chem., 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

[Matting agent (fine particles)]
Matting agents (fine particles) that can be used as additives in the cellulose acylate solution include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, Mention may be made of hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable from the viewpoint of low turbidity, and silicon dioxide is particularly preferable. The silicon dioxide fine particles preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.
The amount of silicon dioxide fine particles used is preferably 0.01 to 0.3 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate.

These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, and these fine particles are present as aggregates of primary particles in the film, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably from 0.2 μm to 1.5 μm, more preferably from 0.4 μm to 1.2 μm, and most preferably from 0.6 μm to 1.1 μm. When it is larger than 1.5 μm, the haze becomes strong, and when it is smaller than 0.2 μm, the effect of preventing stain is reduced.
The primary and secondary particle diameters are determined by observing the particles in the film with a scanning electron microscope and using the diameter of a circle circumscribing the particles as the particle diameter. Also, 200 particles are observed at different locations, and the average value is taken as the average particle diameter.

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

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

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

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

Next, the organic solvent in which the cellulose acylate used in the present invention is dissolved will be described.
In the present invention, any of a chlorinated solvent containing a chlorinated organic solvent as a main solvent and a non-chlorinated solvent not containing a chlorinated organic solvent can be used as the organic solvent.

(Chlorine solvent)
In preparing the cellulose acylate solution used in the present invention, a chlorinated organic solvent is preferably used as the main solvent. In the present invention, the type of the chlorinated organic solvent is not particularly limited as long as the object can be achieved within the range in which cellulose acylate can be dissolved and cast and formed. These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is necessary to use at least 50% by mass of dichloromethane in the total amount of the organic solvent. Other organic solvents used in combination with the chlorinated organic solvent in the present invention will be described below. That is, as another preferable organic solvent, a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms is preferable. Esters, ketones, ethers and alcohols may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a solvent. You may have group simultaneously. In the case of a solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

The alcohol used in combination with the chlorinated organic solvent may be linear, branched or cyclic, and among them, saturated aliphatic hydrocarbon is preferable. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.
Examples of combinations of chlorinated organic solvents and other organic solvents include the following compositions, but are not limited thereto.

Dichloromethane / methanol / ethanol / butanol (80/10/5/5, parts by mass),
Dichloromethane / acetone / methanol / propanol (80/10/5/5, parts by mass),
Dichloromethane / methanol / butanol / cyclohexane (80/10/5/5, parts by mass),
Dichloromethane / methyl ethyl ketone / methanol / butanol (80/10/5/5, parts by mass),
・ Dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/10/5/7, parts by mass)
・ Dichloromethane / cyclopentanone / methanol / isopropanol (80/10/5/8, part by mass)
Dichloromethane / methyl acetate / butanol (80/10/10, parts by mass),
Dichloromethane / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
・ Dichloromethane / 1, 3 dioxolane / methanol / ethanol (70/20/5/5, part by mass),
Dichloromethane / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),
・ Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (70/10/10/5/5, parts by mass),
Dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass),
Dichloromethane / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass),
Dichloromethane / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass),
And so on.

(Non-chlorine solvent)
Next, a non-chlorine organic solvent that is preferably used in preparing the cellulose acylate solution used in the present invention will be described. In the present invention, the non-chlorine organic solvent is not particularly limited as long as the object can be achieved as long as the cellulose acylate can be dissolved and cast and formed into a film. The non-chlorine organic solvent used in the present invention is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. The ester, ketone and ether may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent, such as an alcoholic hydroxyl group. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The non-chlorine organic solvent used in the above cellulose acylate is selected from the various viewpoints described above, and is preferably as follows. That is, the non-chlorine solvent is preferably a mixed solvent containing the non-chlorine organic solvent as a main solvent, and is a mixed solvent of three or more different solvents, wherein the first solvent is methyl acetate, ethyl acetate, At least one selected from methyl formate, ethyl formate, acetone, dioxolane, and dioxane, or a mixture thereof; the second solvent is selected from ketones having 4 to 7 carbon atoms or acetoacetate; The solvent is a mixed solvent selected from alcohols or hydrocarbons having 1 to 10 carbon atoms, more preferably alcohols having 1 to 8 carbon atoms. Note that when the first solvent is a mixed liquid of two or more kinds of solvents, the second solvent may be omitted. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, or a mixed solvent thereof. It may be.

  The alcohol as the third solvent may be linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene. These alcohols and hydrocarbons as the third solvent may be used alone or in combination of two or more, and are not particularly limited. As the third solvent, preferred specific compounds include alcohol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane, Are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol.

The mixing ratio of the above three types of mixed solvents is 20 to 95% by mass for the first solvent, 2 to 60% by mass for the second solvent, and 2 to 30% by mass for the third solvent in the total amount of the mixed solvent. The first solvent is preferably 30 to 90% by mass, the second solvent is 3 to 50% by mass, and the third alcohol is preferably 3 to 25% by mass. . In particular, it is preferable that the first solvent is 30 to 90% by mass, the second solvent is 3 to 30% by mass, and the third solvent is alcohol and 3 to 15% by mass. The non-chlorine-based organic solvent used in the present invention described above is more specifically described in JIII Journal of Technical Disclosure No. 2001-1745 (issued March 15, 2001, Invention Association) p. 12-16. Preferred combinations of non-chlorine organic solvents of the present invention can include the following, but are not limited thereto.

-Methyl acetate / acetone / methanol / ethanol / butanol (75/10/5/5/5, parts by mass),
-Methyl acetate / acetone / methanol / ethanol / propanol (75/10/5/5/5, parts by mass),
Methyl acetate / acetone / methanol / butanol / cyclohexane (75/10/5/5/5, parts by mass),
・ Methyl acetate / acetone / ethanol / butanol (81/8/7/4, parts by mass)
・ Methyl acetate / acetone / ethanol / butanol (82/10/4/4, parts by mass)
・ Methyl acetate / acetone / ethanol / butanol (80/10/4/6, part by mass)
Methyl acetate / methyl ethyl ketone / methanol / butanol (80/10/5/5, parts by mass),
-Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/10/5/7, parts by mass)
Methyl acetate / cyclopentanone / methanol / isopropanol (80/10/5/8, parts by mass),
・ Methyl acetate / acetone / butanol (85/5/5, part by mass),
Methyl acetate / cyclopentanone / acetone / methanol / butanol (60/15/15/5/6, parts by mass),
-Methyl acetate / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
・ Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, part by mass),
・ Methyl acetate / 1,3-dioxolane / methanol / ethanol (70/20/5/5, parts by mass),
-Methyl acetate / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),

・ Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, part by mass),
-Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass)
Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass),
Acetone / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass),
Acetone / 1,3-dioxolane / ethanol / butanol (65/20/10/5, parts by mass),
1,3-dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (55/20/10/5/5/5, parts by mass)
And so on.
Further, a cellulose acylate solution prepared by the following method can also be used.
A method of preparing a cellulose acylate solution with methyl acetate / acetone / ethanol / butanol (81/8/7/4, parts by mass), adding 2 parts by weight of butanol after filtration and concentration, and methyl acetate / acetone / ethanol / Butanol (84/10/4/2, part by mass) A cellulose acylate solution was prepared, and after filtration and concentration, 4 parts by weight of butanol was added. Methyl acetate / acetone / ethanol (84/10/6, In addition to the above non-chlorine organic solvent of the present invention, dichloromethane is added to the dope used in the present invention for the addition of 5 parts by weight of butanol after filtration and concentration. You may make it contain 10 mass% or less of the total amount of organic solvents.

(Characteristics of cellulose acylate solution)
The cellulose acylate solution is preferably a solution obtained by dissolving cellulose acylate in the organic solvent at a concentration of 10 to 30% by mass from the viewpoint of film forming casting suitability, and more preferably 13 to 27% by mass. It is particularly preferably 15 to 25% by mass. The method for carrying out the cellulose acylate at these concentrations may be carried out so that the cellulose acylate has a predetermined concentration at the stage of dissolution, or it is prepared as a low-concentration solution (for example, 9 to 14% by mass) and then concentrated as described later. You may adjust to a predetermined high concentration solution by a process. Furthermore, after preparing a high-concentration cellulose acylate solution in advance, various additives may be added to obtain a predetermined low-concentration cellulose acylate solution, and any method is suitable for the cellulose acylate solution concentration of the present invention. There will be no particular problem if it is implemented.

Next, in the present invention, the aggregate molecular weight of cellulose acylate in a diluted solution in which the cellulose acylate solution is 0.1 to 5% by mass with an organic solvent having the same composition is 150,000 to 15 million. It is preferable in terms of solubility. More preferably, the associated molecular weight is 180,000 to 9 million. This associated molecular weight can be determined by a static light scattering method. In that case, it is preferable to dissolve so that the inertial square radius required at the same time is 10 to 200 nm. A more preferable inertial square radius is 20 to 200 nm. Furthermore, it is preferable to dissolve so that the second virial coefficient is −2 × 10 ⁻⁴ to + 4 × 10 ^−4, and more preferably, the second virial coefficient is −2 × 10 ⁻⁴ to + 2 × 10 ^−4. It is.

Here, the definition of the associated molecular weight, the inertial square radius and the second virial coefficient in the present invention will be described. These are measured using the static light scattering method according to the following method. Although the measurement is performed in a dilute region for the convenience of the apparatus, these measured values reflect the behavior of the dope in the high concentration region of the present invention.
First, cellulose acylate is dissolved in a solvent used for the dope to prepare 0.1 mass%, 0.2 mass%, 0.3 mass%, and 0.4 mass% solutions. In order to prevent moisture absorption, the cellulose acylate is dried at 120 ° C. for 2 hours, and is measured at 25 ° C. and 10% RH. The dissolution method is carried out according to the method employed at the time of dope dissolution (room temperature dissolution method, cooling dissolution method, high temperature dissolution method). Subsequently, the solution and the solvent are filtered through a 0.2 μm Teflon filter. The filtered solution is measured for static light scattering at intervals of 10 degrees from 30 degrees to 140 degrees at 25 ° C. using a light scattering measuring device (DLS-700 manufactured by Otsuka Electronics Co., Ltd.). The obtained data is analyzed by the BERRY plot method. In addition, the refractive index required for this analysis uses the value of the solvent calculated | required with the Abbe refractive system, and the refractive index gradient (dn / dc) uses the differential refractometer (Otsuka Electronics Co., Ltd. product DRM-1021). Measure using the solvent and solution used for light scattering measurement.

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

  It is preferable that the cellulose acylate solution has a viscosity and a dynamic storage elastic modulus within the ranges described below because it is easy to cast. 1 mL of the sample solution is measured with a rheometer (CLS 500) using a Steel Cone having a diameter of 4 cm / 2 ° (both manufactured by TA Instruments). Measurement conditions were measured at Oscillation Step / Temperature Ramp, varying from 40 ° C to -10 ° C at 2 ° C / min, and static non-Newtonian viscosity n * (Pa · s) at 40 ° C and storage at -5 ° C Obtain the elastic modulus G '(Pa). The sample solution is preliminarily kept at the measurement start temperature until the liquid temperature becomes constant, and then the measurement is started. In the present invention, the viscosity at 40 ° C. is 1 to 400 Pa · s, the dynamic storage elastic modulus at 15 ° C. is preferably 500 Pa or more, and more preferably the viscosity at 40 ° C. is 10 to 200 Pa · s. And the dynamic storage elastic modulus in 15 degreeC is 100-1 million. Furthermore, it is preferable that the dynamic storage elastic modulus at a low temperature is large. For example, when the casting support is −5 ° C., the dynamic storage elastic modulus is preferably 10,000 to 1,000,000 Pa at −5 ° C. When the body is at −50 ° C., the dynamic storage elastic modulus at −50 ° C. is preferably 10,000 to 5 million Pa.

  In the present invention, by using the above-mentioned specific cellulose acylate, a high concentration dope can be obtained, and a cellulose acylate solution having a high concentration and excellent stability can be obtained without depending on the means of concentration. Furthermore, in order to make it easy to melt | dissolve, after making it melt | dissolve at a low density | concentration, you may concentrate using a concentration means. The concentration method is not particularly limited. For example, the low-concentration solution is guided between the cylindrical body and the rotation trajectory of the outer periphery of the rotating blade rotating in the circumferential direction, and the temperature between the solution and the solution. A method of obtaining a high-concentration solution while evaporating the solvent by giving a difference (for example, JP-A-4-259511), a heated low-concentration solution is blown into the container from the nozzle, and the solution is applied from the nozzle to the inner wall of the container In which the solvent is flash evaporated and the solvent vapor is withdrawn from the container and the concentrated solution is withdrawn from the bottom of the container (eg, US Pat. No. 2,541,012, US Pat. No. 2,858,229, US Pat. No. 4,414,341, US Pat. No. 4,504,355, etc.).

  Prior to casting, it is preferable to filter off foreign matters such as undissolved matter, dust, and impurities using a suitable filter medium such as a wire mesh or flannel. For the filtration of the cellulose acylate solution, it is preferable to use a filter having an absolute filtration accuracy of 0.1 to 100 μm, and it is more preferable to use a filter having an absolute filtration accuracy of 0.5 to 25 μm. The thickness of the filter is preferably 0.1 to 10 mm, and more preferably 0.2 to 2 mm. In that case, the filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, further 1.0 MPa or less, and particularly preferably 0.2 MPa or less. As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, fluororesins such as tetrafluoroethylene resin can be preferably used, and ceramics, metals and the like are particularly preferably used. The viscosity of the cellulose acylate solution immediately before film formation may be in a range that can be cast during film formation, and is usually prepared in a range of 10 Pa · s to 2000 Pa · s, preferably 30 Pa · s to 1000 Pa. · S is more preferable, and 40 Pa · s to 500 Pa · s is more preferable. The temperature at this time is not particularly limited as long as it is a temperature at the time of casting, but is preferably −5 to + 70 ° C., more preferably −5 to + 55 ° C.

(Membrane production; production method of cellulose acylate film and production method of protective film of the present invention)
Next, the manufacturing method of the said cellulose acylate film is demonstrated below. When a protective film consists only of the said cellulose acylate film, the following description is applied to the manufacturing method of the protective film of this invention.
The manufacturing method of the protective film of the present invention will be described. The manufacturing method of the protective film of the present invention is biaxial at a stretching ratio of 30 to 100% in the predetermined X direction and 10 to 60% in the Y direction orthogonal to the X direction. Stretch.
Further, stretching in at least one direction of the X direction and the Y direction is biaxially stretched at a stretching speed of 70 to 200% / min. The film surface temperature at the time of extending | stretching at least one direction among a X direction and a Y direction is 130-180 degreeC. The amount of residual solvent when peeling off from the support is 50 to 100% by mass. The residual solvent amount at the end of biaxial stretching in the X direction and the Y direction is 15 to 30% by mass.
In the following, description will be given in order.
The cellulose acylate film can be obtained by forming a film using the cellulose acylate solution. As the film forming method and equipment, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support. Both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film for electronic displays, in addition to the solution casting film forming apparatus, surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. Therefore, a coating device is often added. Although each manufacturing process is described briefly below, it is not limited to these.

  First, the prepared cellulose acylate solution (dope) is casted on a drum or band when a cellulose acylate film is produced by a solvent cast method, and the solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is 5 to 40% by mass. The surface of the drum or band is preferably finished in a mirror state. The dope is preferably cast on a drum or band having a surface temperature of 30 ° C. or lower, and particularly preferably a metal support temperature of −10 to 20 ° C. Further, JP 2000-301555, JP 2000-301558, JP 07-032391, JP 03-193316, JP 05-086212, JP 62-037113, JP 02-276607. The methods described in JP-A Nos. 55-014201, 02-111511, and 02-208650 can be used in the present invention.

(Multilayer casting)
The cellulose acylate solution may be cast as a single layer liquid on a smooth band or drum as a metal support, or a plurality of cellulose acylate liquids of two or more layers may be cast. When casting a plurality of cellulose acylate solutions, produce a film while casting and laminating a solution containing cellulose acylate from a plurality of casting openings provided at intervals in the traveling direction of the metal support. For example, the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. Alternatively, a film may be formed by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, This can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Further, a cellulose acylate film in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution, and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded. A casting method may be used. Furthermore, it is also a preferred embodiment that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution. Alternatively, by using two casting ports, peeling the film formed on the metal support by the first casting port, and performing the second casting on the side that was in contact with the metal support surface, A film may be prepared, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Furthermore, the cellulose acylate solution can be cast by simultaneously casting other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer).

  In the conventional single-layer liquid, it is necessary to extrude a high-concentration and high-viscosity cellulose acylate solution in order to obtain the required film thickness. In many cases, this causes a problem such as a fault or flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also the use of a concentrated cellulose acylate solution can reduce the drying load and increase the film production speed. In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, and more preferably 2 to 30%. Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness. In the case of co-casting, a cellulose acylate film having a laminated structure can be produced by co-casting cellulose acylate solutions having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent. For example, a cellulose acylate film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. It is also possible to change the type of plasticizer and ultraviolet absorber between the core layer and the skin layer. For example, the skin layer contains at least one of a low-volatile plasticizer and an ultraviolet absorber, and the core layer is made plastic. It is also possible to add an excellent plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect to contain a peeling accelerator only in the skin layer on the metal support side. It is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling drum method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer. Further, the viscosity of the solution containing cellulose acylate during casting may be different between the skin layer and the core layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity.

(Casting)
As a solution casting method, a method in which the prepared dope is uniformly extruded from a pressure die onto a metal support, and a method using a doctor blade in which the film thickness of the dope once cast on the metal support is adjusted with a blade. Alternatively, there is a method using a reverse roll coater that adjusts with a reverse rotating roll, and a method using a pressure die is preferable. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods listed here, it can be carried out by various methods of casting a cellulose triacetate solution known in the art, and by setting each condition in consideration of differences in the boiling point of the solvent used, etc. The same effects as described in the above publication can be obtained. The endlessly running metal support used to produce the cellulose acylate film suitable for the present invention includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt (band and band) which is mirror-finished by surface polishing. May be used). One or two or more pressure dies used for producing a cellulose acylate film suitable for the present invention may be installed above the metal support. Preferably 1 or 2 groups. When two or more units are installed, the amount of dope to be cast may be divided into various ratios for each die, or the dope may be fed to the dies from each of a plurality of precision quantitative gear pumps. The temperature of the cellulose acylate solution used for casting is preferably −10 to 55 ° C., more preferably 25 to 50 ° C. In that case, all of the processes may be the same, or may be different at various points in the process. If they are different, the temperature may be a desired temperature just before casting.

(Dry)
The drying of the dope on the metal support involved in the production of the cellulose acylate film is generally performed by applying hot air from the surface side of the metal support (drum or belt), that is, the surface of the web on the metal support, A method of applying hot air from the back of the drum or belt, contacting the temperature-controlled liquid from the back of the belt or drum opposite the dope casting surface, and heating the drum or belt by heat transfer to control the surface temperature Although there is a heat transfer method, the back surface liquid heat transfer method is preferable. The surface temperature of the metal support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the metal support, the temperature should be set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent. Is preferred. This is not the case when the casting dope is cooled and peeled off without drying.
The Re value and Rth value of the cellulose acylate film can also be adjusted by adjusting the temperature on the metal support on which the dope film is cast, the temperature and amount of drying air applied to the dope film cast on the metal support. Can be adjusted. In particular, the Rth value is greatly affected by the drying conditions on the metal support. Increasing the temperature of the metal support, or increasing the temperature of the drying air applied to the dope film, or increasing the air volume of the drying air, that is, increasing the amount of heat applied to the dope film, lowers the Rth value. Rth is increased by reducing. In particular, the drying of the first half part immediately after casting and before peeling off greatly affects the Rth value.

(Extension process)
The retardation of the cellulose acylate film suitable for the present invention can be adjusted by stretching treatment. Furthermore, there is also a method of positively stretching in the width direction. For example, JP-A-62-115035, JP-A-4-152125, JP-A-4-284111, JP-A-4-298310, and JP-A-11 -48271, and the like. This stretches the produced film in order to increase the front retardation value of the cellulose acylate film.
The film is stretched simultaneously or sequentially by biaxial stretching. In order to achieve a large optical anisotropy, it is necessary to stretch the film at a high stretch ratio, which is 30 to 100% in the predetermined X direction, preferably 50 to 100%, particularly preferably 60 to 100%, Biaxial stretching is preferably performed at a stretching ratio of 10 to 60%, preferably 30 to 60%, particularly preferably 40 to 60% in the Y direction orthogonal to the X direction.
The X direction and the Y direction may be perpendicular to each other, but the X direction is preferably the film width direction and the Y direction is the film longitudinal direction (flow direction). Further, “orthogonal” means that the Y direction is within a range of 90 ° ± 5 ° with respect to the X direction.
A large optical anisotropy can be obtained by setting the draw ratio in the X direction and the draw ratio in the Y direction within the above ranges.
In addition, a draw ratio means extending | stretching to the length of twice the length of the film of an unstretched state, for example, when set to 100% of draw ratio.
The film is stretched under heating conditions. In order to achieve a large optical anisotropy, it is necessary to stretch the film at a high stretching ratio. For this purpose, the film surface temperature during stretching is higher than the apparent glass transition temperature Tg of the film during stretching. Higher is preferred. In the present invention, the acylate film is stretched at 130 to 180 ° C. The film is preferably stretched at 140 to 180 ° C, more preferably 150 to 180 ° C.
In order to implement a high draw ratio, the residual solvent amount of the film during stretching may be increased instead of increasing the film surface temperature during stretching. Specifically, the residual solvent amount at the time of stretching can be defined by the residual solvent amount at the time of peeling off the web from the support or the residual solvent amount at the end of stretching. The amount of residual solvent at the time of peeling is 50 to 100% by mass, preferably 60 to 100% by mass, more preferably 70 to 100% by mass, and most preferably 80 to 100% by mass. The residual solvent amount at the end of stretching is 15 to 30% by mass, and preferably 20 to 30% by mass. The residual solvent amount (%) is defined by (A−B) / B × 100. Here, A is the mass of the web, and B is the mass after drying the web at 140 ° C. for 60 minutes.
Another means for achieving a large optical anisotropy is to increase the stretching speed. In the present invention, the stretching speed in the X or Y direction is 70 to 200% / min, preferably 80 to 200% / min, and most preferably 90 to 200% / min.
In order to reduce variation in the in-plane slow axis in the width direction, it is preferable to provide a relaxation step after transverse stretching. In the relaxation step, it is preferable to adjust the width of the film after relaxation to a range of 100 to 70% (relaxation rate of 0 to 30%) with respect to the width of the film before relaxation. The temperature in the relaxation step is preferably the apparent glass transition temperature Tg-10 to Tg + 20 ° C. of the film.
Here, the apparent Tg of the film in the stretching process is that the film containing the residual solvent is enclosed in an aluminum pan, and the temperature is increased from 25 ° C. to 150 ° C. at 20 ° C./min with a differential scanning calorimeter (DSC). Tg was determined by obtaining an endothermic curve.

The film thickness of the cellulose acylate film obtained after drying is preferably in the range of 20 to 70 μm in consideration of forming the protective film only with the cellulose acylate film, and more preferably in the range of 20 to 60 μm. The range of 20-50 micrometers is especially preferable. In order to reduce the internal haze of the film, it is effective to reduce the film thickness.
Further, in order to improve the display unevenness due to Re, Rth, and slow axis angle affected by the film thickness unevenness of the film, the film thickness unevenness is preferably 0.5 μm or less, and 0.4 μm or less. More preferably, it is more preferably 0.3 μm or less. In order to reduce the film thickness unevenness of the film, it is effective to perform a stretching treatment.
The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like so as to obtain a desired thickness. The film thickness can also be adjusted by stretching. The width of the cellulose acylate film obtained as described above is preferably 0.5 to 3 m, more preferably 0.6 to 2.5 m, and still more preferably 0.8 to 2.2 m. The length is preferably 100 to 10000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, knurling is preferably applied to at least one end, the width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. This may be a single push or a double push.

In this specification, Re (λ) and Rth (λ) respectively represent front retardation and retardation in the film thickness direction at wavelength λ. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA WR (manufactured by Oji Scientific Instruments). Rth (λ) has an incident angle of −50 ° with respect to the film normal direction, with the film normal direction being the incident angle of 0 ° and the in-plane slow axis (determined by KOBRA WR) being the tilt axis (rotation axis). KOBRA WR is calculated based on the retardation value measured by making light of wavelength λ nm incident every 10 ° to + 50 °, the assumed value of the average refractive index, and the input film thickness value. Here, as the assumed value of the average refractive index, values in the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx-nz) / (nx-ny) is further calculated from the calculated nx, ny, and nz.
The variation in the Re (590) value of the full width is preferably ± 5 nm, and more preferably ± 3 nm. Further, the variation of the Rth (590) value is preferably ± 10 nm, and more preferably ± 5 nm. Moreover, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.

  Re (λ) and Rth (λ) of the protective film A preferably satisfy the following formulas (VII) and (VIII).

Formula (VII): 20 nm ≦ Re (590) ≦ 200 nm
Formula (VIII): 60 nm ≦ Rth (590) ≦ 400 nm

[In the formula, Re (λ) is a front retardation value (unit: nm) at a wavelength λnm, and Rth (λ) is a retardation value (unit: nm) in a film thickness direction at a wavelength λnm. ]
By satisfying the formula (VII) and the formula (VIII), a display characteristic with a wide viewing angle and a favorable change in color viewing angle can be obtained in the liquid crystal display device.
When cellulose acylate film is used in the VA mode, a mode in which a total of two sheets are used on each side of the cell (two-sheet type) and a mode in which only one of the upper and lower sides of the cell is used (one-sheet type) There are two ways.
In the case of the two-sheet type, Re is preferably 20 to 100 nm, and more preferably 30 to 70 nm. Rth is preferably 70 to 300 nm, more preferably 100 to 200 nm.
In the case of a single sheet type, Re is preferably 30 to 150 nm, and more preferably 40 to 100 nm. Rth is preferably from 100 to 300 nm, more preferably from 150 to 250 nm.

  The variation of the slow axis angle in the film plane of the cellulose acylate film is preferably in the range of -2 degrees to +2 degrees with respect to the reference direction of the roll film, and in the range of -1 degrees to +1 degree. Is more preferable, and most preferably in the range of -0.5 degree to +0.5 degree. Here, the reference direction is the longitudinal direction of the roll film when the cellulose acylate film is longitudinally stretched, and the width direction of the roll film when laterally stretched.

The cellulose acylate film has a difference ΔRe (= Re 10% RH−Re 80% RH) between the Re value at 25 ° C. and 10% RH and the Re value at 25 ° C. and 80% RH of 0 to 10 nm and 25 ° C. and 10%. The difference ΔRth (= Rth 10% RH−Rth 80% RH) between the Rth value at RH and the Rth value at 25 ° C. and 80% RH is 0 to 30 nm in order to reduce the color change with time of the liquid crystal display device. preferable.
In addition, the cellulose acylate film preferably has an equilibrium water content of 3.2% or less at 25 ° C. and 80% RH in order to reduce the color change with time of the liquid crystal display device.
The moisture content is measured by measuring a cellulose acylate film sample 7 mm × 35 mm by a Karl Fischer method using a moisture meter and a sample drying apparatus (CA-03, VA-05, both Mitsubishi Chemical Corporation). It is calculated by dividing the amount of water (g) by the sample mass (g).

The cellulose acylate film has a moisture permeability of 60 ° C., 95% RH, 24 hr (film thickness 80 μm conversion) of 400 g / m ² · 24 hr to 1800 g / m ² · 24 hr. It is preferable for reducing the color change with time.
If the film thickness of the cellulose acylate film is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. Therefore, it is necessary to convert the sample of any film thickness to a standard of 80 μm. Conversion of the film thickness is obtained as (water vapor permeability in terms of 80 μm = measured water vapor permeability × measured film thickness μm / 80 μm).
The measurement method of moisture permeability is “Polymer Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The method described in can be applied.
The glass transition temperature was measured after adjusting the humidity of a cellulose acylate film sample (unstretched) 5 mm × 30 mm at 25 ° C. and 60% RH for 2 hours or more (Vibron: DVA-225 (IT measurement) Measured at a grip distance of 20 mm, a heating rate of 2 ° C./minute, a measurement temperature range of 30 ° C. to 200 ° C., and a frequency of 1 Hz, the vertical axis is the logarithmic axis, the storage elastic modulus, and the horizontal axis is linear When the temperature (° C.) is taken at the axis, the sharp decrease in the storage elastic modulus observed when the storage elastic modulus shifts from the solid region to the glass transition region is drawn with a straight line 1 in the solid region, and a straight line 2 in the glass transition region. Is the temperature at which the storage elastic modulus suddenly decreases and the film begins to soften when the temperature rises, and the temperature at which the film begins to transition to the glass transition region. Therefore, the glass transition temperature Tg (Dynamic viscoelasticity And the.

The elastic modulus was measured by conditioning a protective film (for example, cellulose acylate film) sample 10 mm × 150 mm used in the present invention at 25 ° C. and 60% RH for 2 hours or more, and then using a tensile tester (Strograph-R2 (Toyo Made by Seiki)) at a chuck distance of 100 mm, a temperature of 25 ° C., and a stretching speed of 10 mm / min.
The elastic modulus of the protective film A disposed on the liquid crystal cell side is preferably 2 to 6 GPa in terms of curl adjustment of the polarizing plate, ease of handling of the film at the time of film preparation and polarizing plate preparation, More preferably, it is 3-6 GPa, and it is still more preferable that it is 4-6 GPa.
The elastic modulus of the film can be controlled by selecting a polymer material constituting the film, adding an organic material such as a plasticizer, and adding an inorganic material such as silica fine particles. Moreover, it can also control by the preparation methods of a film, and can control by the solvent seed | species used for dope adjustment, drying conditions, and a draw ratio. In the present invention, the elastic modulus can be particularly preferably determined by the draw ratio.

The haze value of at least one of the protective film A disposed on the liquid crystal cell side and the protective film B disposed on the side opposite to the liquid crystal cell side is 1.0% or less. It is preferable in terms of realizing a high front contrast in the apparatus, and more preferably 0.6% or less.
Here, the haze can be measured as follows.
The haze is measured by measuring a cellulose acylate film sample 40 mm × 80 mm at 25 ° C. and 60% RH with a haze meter (HGM-2DP, Suga Test Instruments) according to JIS K-6714.
The cellulose acylate film preferably has a mass change of 0 to 5% when left for 48 hours under conditions of 80 ° C. and 90% RH.
In addition, the cellulose acylate film has a dimensional change when left for 24 hours under conditions of 60 ° C. and 95% RH, and a dimensional change when left for 24 hours under conditions of 90 ° C. and 5% RH. , Both are preferably 0 to 5%.
It is preferable that the photoelastic coefficient is 50 × 10 ⁻¹³ cm ² / dyne or less in order to reduce the color change with time of the liquid crystal display device.
As a specific measuring method, a tensile stress is applied to the major axis direction of a 10 mm × 100 mm cellulose acylate film sample, and the retardation at that time is measured with an ellipsometer (M150, JASCO Corporation). The photoelastic coefficient was calculated from the amount of change in retardation with respect to.

(Protective films A and B)
Next, the protective films A and B will be described.
The polarizing plate is usually composed of a polarizer and two transparent protective films disposed on both sides thereof. In the present invention, as described above, it is preferable to use the cellulose acylate film as at least one protective film A. The other protective film B may be the above cellulose acylate film or a normal cellulose acetate film. In the present invention, the curl of the polarizing plate is adjusted by adjusting the relationship between the thickness of the protective film on the liquid crystal cell side and the thickness of the protective film on the side opposite to the liquid crystal cell, the elastic modulus, and the hygroscopic expansion coefficient as follows. Can be adjusted within range.

  In the polarizing plate of the present invention, the thickness d1 of the protective film A disposed on the liquid crystal cell side and the thickness d2 of the protective film B disposed on the side opposite to the liquid crystal cell side satisfy the following formula (I). preferable.

  Formula (I): 0.5 × d1 ≦ d2 ≦ 1.2 × d1

By satisfying the above formula (I), polarized light is combined when a protective film having an elastic modulus ratio E2 / E1 of 0.8 to 1.2 and a hygroscopic expansion coefficient ratio C2 / C1 of 0.8 to 1.2 is combined. The curl of the plate is in the range of −30 mm to +15 mm, and preferable results are obtained.
In the polarizing plate of the present invention, the elastic modulus E1 of the protective film disposed on the liquid crystal cell side and the elastic modulus E2 of the protective film disposed on the side opposite to the liquid crystal cell side satisfy the following formula (II). It is preferable. Accordingly, when a protective film having a thickness ratio d2 / d1 of the protective films A and B of 0.8 to 1.2 and a hygroscopic expansion coefficient ratio C2 / C1 of 0.8 to 1.2 is combined, the curl of the polarizing plate is -30 mm to +15 mm. Thus, preferable results are obtained.

  Formula (II): 0.5 × E1 ≦ E2 ≦ 1.2 × E1

  Furthermore, the thickness d1 and elastic modulus E1 of the protective film disposed on the liquid crystal cell side and the thickness d2 and elastic modulus E2 of the protective film disposed on the side opposite to the liquid crystal cell satisfy the following formula (III). Is preferred.

  Formula (III): 0.5 × E1 × d1 ≦ E2 × d2 ≦ 1.2 × E1 × d1

  By satisfying the formula (III), if the ratio C2 / C1 of the hygroscopic expansion coefficient between the protective films A and B is 0.8 or more and 1.2 or less, the thickness ratio d2 / d1 of the protective films A and B is less than 0.8 or 1.2 When combined with a large protective film, or when combined with a protective film having an elastic modulus ratio E2 / E1 of less than 0.8 or greater than 1.2, the curl of the polarizing plate is in the range of −30 mm to +15 mm, and the usable protective film A and protective film can be used. The range of elastic modulus and thickness of B is expanded.

  Furthermore, in the polarizing plate of the present invention, the hygroscopic expansion coefficient C1 of the protective film disposed on the liquid crystal cell side and the hygroscopic expansion coefficient C2 of the protective film disposed on the side opposite to the liquid crystal cell side are expressed by the following formula (IV): It is preferable to satisfy.

  Formula (IV): 0.3 × C1 ≦ C2 ≦ 1.3 × C1

When the humidity at the time of producing a polarizing plate in which the protective film A and the protective film B are bonded to both surfaces of the polarizing film is different from the humidity at the time of attaching the produced polarizing plate to the liquid crystal cell, the hygroscopic expansion of the protective film A and the protective film B If the coefficients differ greatly, the polarizing plate will curl, making it difficult to attach the polarizing plate to the liquid crystal cell. By satisfying the above formula, the polarizing plate curl in the case where the humidity when the polarizing plate is bonded to the liquid crystal cell is different from that at the time of manufacturing the polarizing plate is in the range of −30 mm to +15 mm, and a preferable result is obtained.
In order to reduce the hygroscopic expansion coefficient, it is preferable to use a mixed fatty acid ester of cellulose obtained by substituting the hydroxyl group of cellulose with an acetyl group and an acyl group having 3 or more carbon atoms. It is preferable to use a cellulose acylate having a degree satisfying the following mathematical formulas (IX) and (X).

Formula (IX): 2.8 ≦ A + B ≦ 3.0
Formula (X): 0.5 <B

Here, A and B represent the substitution degree of the acyl group substituted by the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 or more carbon atoms. As the acyl group having 3 or more carbon atoms, those having a large number of carbon atoms are preferred.
The hygroscopic expansion coefficient is measured with a pin gauge from the value L80 obtained by measuring the dimension of a film left at 25 ° C. and 80% RH for 2 hours or longer with a pin gauge. From the obtained value L10, the following equation was used.

  (L10-L80) / (80% RH-10% RH) x 1000000

  The thickness d1, the elastic modulus E1, and the hygroscopic expansion coefficient C1 of the protective film A and the thickness d2, the elastic modulus E2, and the hygroscopic expansion coefficient C2 of the protective film B disposed on the opposite side of the polarizing film are expressed by the following formula (V ) Is preferably satisfied.

  Formula (V): −30 ≦ {(E2 × d2) / (E1 × d1) −1} × 60 + (C2 / C1-1) × 10 ≦ 15

  Any value may be used for the elastic modulus, thickness, and hygroscopic expansion coefficient of the protective film A and the protective film B as long as the numerical formula (V) is satisfied. When the physical properties other than the elastic modulus, thickness, and hygroscopic expansion coefficient are changed, and any one of the elastic modulus, thickness, and hygroscopic expansion coefficient does not satisfy the above formulas (I), (II), and (IV) If the remaining two values are adjusted to satisfy the expression (V), the curling of the polarizing plate can be made a preferable range.

(Production of polarizing film and polarizing plate)
Examples of the polarizing film include an iodine-based polarizer, a dye-based polarizer using a dichroic dye, and a polyene-based polarizer. The iodine polarizer and the dye polarizer are generally produced using a polyvinyl alcohol film. The production method of the polarizing plate of the present invention is not particularly limited, and can be produced by a general method. Hereinafter, the case where a cellulose acylate film is used as a suitable protective film in the present invention will be described as an example. For example, there is a method in which the obtained cellulose acylate film is treated with an alkali and bonded to both sides of a polarizer produced by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed. Examples of the adhesive used to bond the protective film-treated surface and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like. The polarizing plate is composed of a polarizer and a protective film that protects both surfaces of the polarizer, and a protective film may be bonded to one surface of the polarizing plate and a separate film may be bonded to the opposite surface.
The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal cell. Moreover, a separate film is used in order to cover the adhesive layer bonded to a liquid crystal cell, and is used for the surface side which bonds a polarizing plate to a liquid crystal cell.
As shown in FIG. 3, the cellulose acylate film may be bonded to the polarizer so that the transmission axis of the polarizer and the slow axis of the cellulose acylate film (TAC in the figure) are aligned. preferable.
Note that a polarizing plate produced under polarizing cross Nicol has a polarizing plate cross when the orthogonal accuracy between the slow axis of the cellulose acylate film and the absorption axis of the polarizer (axis perpendicular to the transmission axis) is greater than 1 °. The direction of the main refractive index nx of the cellulose acylate film and the polarizing plate when a combination with a liquid crystal cell cannot obtain sufficient black level and contrast when the polarization degree performance under Nicol is lowered and light leakage occurs. The deviation from the direction of the transmission axis is within 1 °, preferably within 0.5 °.

(surface treatment)
The cellulose acylate film can achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a surface treatment. As the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferred. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Regarding these, the details are disclosed in the Invention Association Public Technical Bulletin No. 2001-1745 (issued March 15, 2001, Invention Association) p. 30-32. Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

  The alkali saponification treatment is preferably carried out by a method in which the cellulose acylate film is directly immersed in a saponification solution tank or a method in which the saponification solution is applied to the cellulose acylate film. Examples of the coating method include a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. The solvent of the alkali saponification coating solution has good wettability in order to apply the saponification solution to the cellulose acylate film, and the surface of the cellulose acylate film surface is not formed by the saponification solution solvent. It is preferred to select a solvent that remains good. 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 above 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.

Further, the polarizing plate of the present invention is preferably one in which at least one layer of a hard coat layer, an antiglare layer and an antireflection layer is provided on the surface of the protective film on the other side with the polarizing film of the polarizing plate interposed therebetween. That is, as shown in FIG. 1, it is preferable to provide a functional film such as an antireflection layer on the protective film (TAC2) disposed on the side opposite to the liquid crystal cell when the polarizing plate is used in a liquid crystal display device. It is preferable to provide at least one layer of a hard coat layer, an antiglare layer and an antireflection layer as the functional film. Each layer does not need to be provided as a separate layer. For example, an anti-glare layer is provided as an anti-glare layer and an anti-glare layer by providing the anti-reflection layer or the hard coat layer with an anti-glare function. May be.

(Antireflection layer)
In the present invention, the intermediate refractive index layer, the high refractive index layer, and the low refractive index layer are arranged in this order on the antireflection layer or protective film in which at least the light scattering layer and the low refractive index layer are laminated in this order on the protective film. The antireflection layer laminated with is preferably used. Preferred examples thereof are described below. In the former configuration, the specular reflectance is generally 1% or more, which is called a low reflection (LR) film. In the latter configuration, it is possible to realize a mirror reflectivity of 0.5% or less, which is called an Anti Reflection (AR) film.

A preferred example of an antireflection layer (LR film) in which a light scattering layer and a low refractive index layer are provided on a protective film will be described.
In the light scattering layer, mat particles are preferably dispersed, and the refractive index of the material other than the mat particles in the light scattering layer is preferably in the range of 1.50 to 2.00, and the low refractive index The refractive index of the layer is preferably in the range of 1.20 to 1.49. In the present invention, the light scattering layer has both antiglare properties and hard coat properties, and may be composed of one layer or a plurality of layers, for example, 2 to 4 layers.

The antireflection layer has an uneven surface shape with a center line average roughness Ra of 0.08 to 0.40 μm, a 10-point average roughness Rz of 10 times or less of Ra, an average mountain valley distance Sm of 1 to 100 μm, and an uneven depth. Designed so that the standard deviation of the height of the convex part from the part is 0.5 μm or less, the standard deviation of the average mountain valley distance Sm with respect to the center line is 20 μm or less, and the surface with an inclination angle of 0 to 5 degrees is 10% or more. By doing so, sufficient anti-glare properties and a visually uniform matte feeling are achieved, which is preferable. Further, the ratio of the minimum value and the maximum value of the reflectance within the range of a ^* value −2 to 2, b ^* value −3 to 3, and 380 nm to 780 nm under the light source C is 0.5. By being -0.99, the color of reflected light becomes neutral, which is preferable. Moreover, it is preferable that the b ^* value of the transmitted light under the C light source is 0 to 3 because the yellow color of white display when applied to a display device is reduced. In addition, when a 120 μm × 40 μm grid is inserted between the surface light source and the antireflection film of the present invention and the luminance distribution is measured on the film, the standard deviation of the luminance distribution is 20 or less. Glare when applying the film of the present invention is reduced, which is preferable.

  The antireflective layer that can be used in the present invention suppresses reflection of external light by setting its optical characteristics to a specular reflectance of 2.5% or less, a transmittance of 90% or more, and a 60 degree gloss of 70% or less. This is preferable because visibility is improved. In particular, the specular reflectance is more preferably 1% or less, and most preferably 0.5% or less. Haze 20% to 50%, ratio of internal haze / total haze value 0.3 to 1, haze value after formation of low refractive index layer from haze value up to light scattering layer within 15%, comb width 0 .Transmission image sharpness at 5 mm to 20% to 50%, vertical transmission light / transmittance ratio of 2 degrees from vertical to 1.5 to 5.0, preventing glare on a high-definition LCD panel, Reduction of blurring of characters and the like is achieved, which is preferable.

(Low refractive index layer)
The refractive index of the low refractive index layer that can be used in the present invention is preferably 1.20 to 1.49, more preferably 1.30 to 1.44. Furthermore, the low refractive index layer preferably satisfies the following formula (XVII) from the viewpoint of reducing the reflectance.

  Formula (XVII): (m / 4) × 0.7 <n1d1 <(m / 4) × 1.3

  In the formula, m is a positive odd number, n1 is the refractive index of the low refractive index layer, and d1 is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 500 to 550 nm.

The material for forming the low refractive index layer will be described below.
The low refractive index layer preferably contains a fluorine-containing polymer as a low refractive index binder. The fluorine polymer is preferably a fluorine-containing polymer that is crosslinked by heat or ionizing radiation with a coefficient of dynamic friction of 0.03 to 0.20, a contact angle with water of 90 to 120 °, and a sliding angle of pure water of 70 ° or less. When the polarizing plate of the present invention is mounted on an image display device, the lower the peel strength from a commercially available adhesive tape, the easier it is to peel off after sticking a seal or memo, and 500 gf or less is preferred when measured with a tensile tester. 300 gf or less is more preferable, and 100 gf or less is most preferable. Further, the higher the surface hardness measured with a microhardness meter, the harder it is to scratch, preferably 0.3 GPa or more, more preferably 0.5 GPa or more.

  Examples of the fluorine-containing polymer used in the low refractive index layer include hydrolysates and dehydration condensates of perfluoroalkyl group-containing silane compounds (for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane). In addition, a fluorine-containing copolymer having a fluorine-containing monomer unit and a structural unit for imparting crosslinking reactivity as constituent components can be mentioned.

  Specific examples of the fluorine-containing monomer include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, perfluorooctylethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc. ), A part of (meth) acrylic acid or a fully fluorinated alkyl ester derivative (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) or M-2020 (manufactured by Daikin)), a complete or partially fluorinated vinyl ether, and the like. Perfluoroolefins are preferred, and hexafluoropropylene is particularly preferred from the viewpoints of refractive index, solubility, transparency, availability, and the like.

  As structural units for imparting crosslinking reactivity, structural units obtained by polymerization of monomers having a self-crosslinkable functional group in the molecule in advance such as glycidyl (meth) acrylate and glycidyl vinyl ether, carboxyl groups, hydroxy groups, amino acids Polymerization of monomers having a group, a sulfo group, etc. (eg (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, maleic acid, crotonic acid, etc.) The resulting structural unit, a structural unit in which a crosslinking reactive group such as a (meth) acryloyl group is introduced into these structural units by a polymer reaction (for example, an acrylic acid chloride is allowed to act on a hydroxy group). And the like.

  In addition to the above-mentioned fluorine-containing monomer units and structural units for imparting crosslinking reactivity, monomers not containing fluorine atoms can be copolymerized as appropriate from the viewpoints of solubility in solvents and film transparency. There are no particular limitations on the monomer units that can be used in combination. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid 2) -Ethylhexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl) Vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate etc.), acrylamides (N-tert-butylacrylamide, N- Black hexyl acrylamide), methacrylamides, and acrylonitrile derivatives.

  As described in JP-A-10-25388 and JP-A-10-147739, a curing agent may be appropriately used in combination with the above polymer.

(Light scattering layer)
The light scattering layer is formed for the purpose of imparting to the film a light diffusibility due to at least one of surface scattering and internal scattering and a hard coat property for improving the scratch resistance of the film. Therefore, it is formed including a binder for imparting hard coat properties, matte particles for imparting light diffusibility, and inorganic fillers for increasing the refractive index, preventing crosslinking shrinkage, and increasing the strength as necessary. The Further, by providing such a light scattering layer, the light scattering layer also functions as an antiglare layer, and the polarizing plate has an antiglare layer.

  The thickness of the light scattering layer is preferably 1 to 10 μm and more preferably 1.2 to 6 μm for the purpose of imparting hard coat properties. If it is too thin, the hard property will be insufficient, and if it is too thick, curling and brittleness will deteriorate and the workability will be insufficient.

  The binder of the light scattering layer is preferably a polymer having a saturated hydrocarbon chain or a polyether chain as the main chain, and more preferably a polymer having a saturated hydrocarbon chain as the main chain. The binder polymer preferably has a crosslinked structure. As the binder polymer having a saturated hydrocarbon chain as a main chain, a polymer of an ethylenically unsaturated monomer is preferable. As the binder polymer having a saturated hydrocarbon chain as the main chain and having a crosslinked structure, a (co) polymer of monomers having two or more ethylenically unsaturated groups is preferable. In order to make the binder polymer have a high refractive index, the monomer structure contains an aromatic ring, at least one atom selected from halogen atoms other than fluorine, sulfur atoms, phosphorus atoms, and nitrogen atoms. You can also choose.

  Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di ( (Meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol Tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3-si Rhohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), modified ethylene oxide, vinylbenzene and derivatives thereof (eg, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1, 4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide. Two or more of these monomers may be used in combination.

  Specific examples of the high refractive index monomer include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like. Two or more of these monomers may be used in combination.

Polymerization of the monomer having an ethylenically unsaturated group can be performed by irradiation with ionizing radiation or heating in the presence of a photo radical initiator or a thermal radical initiator.
Therefore, a coating liquid containing a monomer having an ethylenically unsaturated group, a photo radical initiator or a thermal radical initiator, mat particles, and an inorganic filler is prepared, and the coating liquid is applied onto a protective film and then ionizing radiation or heat. It can be cured by a polymerization reaction to form an antireflection film. As these photo radical initiators, known ones can be used.

The polymer having a polyether as the main chain is preferably a ring-opening polymer of a polyfunctional epoxy compound. The ring-opening polymerization of the polyfunctional epoxy compound can be performed by irradiation with ionizing radiation or heating in the presence of a photoacid generator or a thermal acid generator.
Therefore, a coating liquid containing a polyfunctional epoxy compound, a photoacid generator or a thermal acid generator, matte particles and an inorganic filler is prepared, and the coating liquid is applied on a protective film and then cured by ionizing radiation or heat polymerization reaction. Thus, an antireflection film can be formed.

Instead of or in addition to a monomer having two or more ethylenically unsaturated groups, a monomer having a crosslinkable functional group is used to introduce a crosslinkable functional group into the polymer, and by reaction of this crosslinkable functional group, A crosslinked structure may be introduced into the binder polymer.
Examples of the crosslinkable functional group include isocyanate group, epoxy group, aziridine group, oxazoline group, aldehyde group, carbonyl group, hydrazine group, carboxyl group, methylol group and active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. That is, in the present invention, the crosslinkable functional group may not react immediately but may exhibit reactivity as a result of decomposition.
These binder polymers having a crosslinkable functional group can form a crosslinked structure by heating after coating.

For the purpose of imparting antiglare properties, the light scattering layer contains matte particles having an average particle size of 1 to 10 μm, preferably 1.5 to 7.0 μm, such as inorganic compound particles or resin particles, for the purpose of imparting antiglare properties. Is done.
As specific examples of the mat particles, inorganic particles such as silica particles and TiO ₂ particles; resin particles such as acrylic particles, crosslinked acrylic particles, polystyrene particles, crosslinked styrene particles, melamine resin particles, and benzoguanamine resin particles are preferable. Can be mentioned. Of these, crosslinked styrene particles, crosslinked acrylic particles, crosslinked acrylic styrene particles, and silica particles are preferable. The shape of the mat particles can be either spherical or irregular.

  Two or more kinds of mat particles having different particle diameters may be used in combination. It is possible to impart anti-glare properties with mat particles having a larger particle size and to impart other optical characteristics with mat particles having a smaller particle size.

  Furthermore, the particle size distribution of the mat particles is most preferably monodisperse, and the particle sizes of the particles are preferably closer to each other. For example, when a particle having a particle size of 20% or more than the average particle size is defined as a coarse particle, the proportion of the coarse particle is preferably 1% or less, more preferably 0.1% of the total number of particles. Or less, more preferably 0.01% or less. Matt particles having such a particle size distribution are obtained by classification after a normal synthesis reaction, and a matting agent having a more preferable distribution can be obtained by increasing the number of classifications or increasing the degree of classification.

The mat particles are contained in the light scattering layer so that the amount of mat particles in the formed light scattering layer is preferably 10 to 1000 mg / m ² , more preferably 100 to 700 mg / m ² .
The particle size distribution of the mat particles is measured by a Coulter counter method, and the measured distribution is converted into a particle number distribution.

The light scattering layer is made of an oxide of at least one metal selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony, in addition to the matte particles, in order to increase the refractive index of the layer. Thus, it is preferable that an inorganic filler having an average particle diameter of 0.2 μm or less, preferably 0.1 μm or less, more preferably 0.06 μm or less is contained. Conversely, in order to increase the difference in refractive index from the mat particles, it is also preferable to use a silicon oxide in order to keep the refractive index of the light scattering layer using the high refractive index mat particles low. The preferred particle size is the same as that of the aforementioned inorganic filler.
Specific examples of the inorganic filler used in the light scattering layer include TiO ₂ , ZrO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ITO and SiO ₂ . TiO ₂ and ZrO ₂ are particularly preferable from the viewpoint of increasing the refractive index. The surface of the inorganic filler is preferably subjected to a silane coupling treatment or a titanium coupling treatment, and a surface treatment agent having a functional group capable of reacting with a binder species on the filler surface is preferably used.
The amount of these inorganic fillers added is preferably 10 to 90% of the total mass of the light scattering layer, more preferably 20 to 80%, and particularly preferably 30 to 75%.
Such a filler does not scatter because the particle size is sufficiently smaller than the wavelength of light, and a dispersion in which the filler is dispersed in a binder polymer behaves as an optically uniform substance.

  The bulk refractive index of the mixture of binder and inorganic filler in the light scattering layer is preferably 1.50 to 2.00, more preferably 1.51 to 1.80. In order to make the refractive index within the above range, the kind and amount ratio of the binder and the inorganic filler may be appropriately selected. How to select can be easily known experimentally in advance.

  In order to ensure surface uniformity such as uneven coating, uneven drying, point defects, etc., the light scattering layer should be coated with either a fluorine-based surfactant or a silicone-based surfactant, or both for forming the light scattering layer. Contained in the composition. In particular, a fluorine-based surfactant is preferably used because an effect of improving surface defects such as coating unevenness, drying unevenness, and point defects of the antireflection film of the present invention appears in a smaller addition amount. The purpose is to increase productivity by giving high-speed coating suitability while improving surface uniformity.

Next, an antireflection layer (AR film) in which a middle refractive index layer, a high refractive index layer, and a low refractive index layer are laminated in this order on the protective film will be described.
The antireflection layer comprising at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) in order on the protective film is designed to have a refractive index satisfying the following relationship. .
High refractive index layer refractive index> Medium refractive index layer refractive index> Protective film refractive index> Low refractive index layer refractive index A hard coat layer may be provided between the protective film and the medium refractive index layer. . Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples thereof include antireflection layers described in 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 (eg, 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 of the antireflection film is composed of a cured film containing at least an inorganic compound fine particle having a high refractive index having an average particle diameter 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, the thing with a refractive index of 1.9 or more is mentioned. Examples thereof 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 fine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agent, etc .: JP-A Nos. 1-295503, 11-153703, 2000-9908, Anionic compounds or organometallic coupling agents: JP 2001-310432 A, etc., core-shell structure with high refractive index particles as a core (JP 2001-166104 A, etc.), specific dispersant combination ( Examples thereof include JP-A No. 11-153703, US Pat. No. 6,210,858B1, and JP-A No. 2002-276069.
Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
More preferable materials include a polyfunctional compound-containing composition having at least two polymerizable groups of at least one of radically polymerizable and cationically polymerizable, a composition containing an organometallic compound containing a hydrolyzable group, And at least one composition selected from compositions containing a partial condensate thereof.
Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.

Further, 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. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.
The refractive index of the high refractive index layer is preferably 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 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. The thickness is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

(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 preferably 1.20 to 1.55. More 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 means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of silicone or introduction of fluorine can be applied.
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.
For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], compounds described in JP-A No. 2000-284102, and 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 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 (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.
The crosslinking or polymerization reaction of at least one of the fluorine-containing polymer having a crosslinking or polymerizable group and the siloxane polymer is performed simultaneously with the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, or the like. It is preferable to form the low refractive index layer by light irradiation or heating after coating.
A sol-gel cured film is also preferred 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.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.
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 is provided on the surface of the protective film in order to impart physical strength to the protective film provided with the antireflection layer. In particular, it is preferably provided between the transparent support 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 in the curable compound is preferably a photopolymerizable functional group. Also, hydrolyzable functional group-containing organometallic compounds and organoalkoxysilyl compounds are preferred.
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 WO0 / 46617.
The high refractive index layer 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 containing particles having an average particle size of 0.2 to 10 μm and imparted with an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
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 amount of wear of the test piece before and after the test, the better.

(Other layers of antireflection layer)
Further, a forward scattering layer, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(Antistatic layer)
In the case of providing an antistatic layer, it is preferable to impart conductivity with a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less. The use of hygroscopic substances, water-soluble inorganic salts, certain surfactants, cationic polymers, anionic polymers, colloidal silica, etc. can give a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ). There is a problem that dependency is large, and sufficient conductivity cannot be secured at low humidity. Therefore, a metal oxide is preferable as the conductive layer material. Some metal oxides are colored, but using these metal oxides as the conductive layer material is not preferable because the entire film is colored. Zn, Ti, Al, In, Si, Mg, Ba, Mo, W, or V can be cited as the metal that forms the metal oxide without coloration, and the metal oxide based on this can be used. Is preferred. Specific examples include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ , V ₂ O ₅ , or a composite oxide thereof. In particular, ZnO, TiO ₂ and SnO ₂ are preferable. Examples of containing different atoms include, for example, additives such as Al and In for ZnO, addition of Sb, Nb and halogen elements for SnO ₂ , and Nb and TA for TiO ₂ . Addition is effective. Furthermore, as described in Japanese Examined Patent Publication No. 59-6235, a material obtained by adhering the above metal oxide to other crystalline metal particles or fibrous materials (for example, titanium oxide) may be used. The volume resistance value and the surface resistance value are different physical properties and cannot be simply compared. However, in order to ensure conductivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less in volume resistance, the conductivity It is sufficient that the layer has a surface resistance value of approximately 10 ⁻¹⁰ (Ω / □) or less, and more preferably 10 ⁻⁸ (Ω / □). The surface resistance value of the conductive layer needs to be measured as a value when the antistatic layer is the outermost layer, and can be measured in the middle of forming the laminated film.

(Liquid crystal display device)
The liquid crystal display device of the present invention includes a liquid crystal display device (first form) using at least one polarizing plate of the present invention, a VA mode and an OCB mode using one of the polarizing plates of the present invention one above and below the cell. And a TN mode liquid crystal display device (second embodiment) and a VA mode liquid crystal display device (third embodiment) using only one of the polarizing plates of the present invention on the backlight side.
Specifically, FIG. 2 shows a liquid crystal display device of a second form. In the liquid crystal display device shown in FIG. 2, the polarizing plates of the present invention are arranged above and below the VA cell, which is a liquid crystal cell, so that the protective film A (TAC1) is located on the liquid crystal cell side.
That is, the protective film A is advantageously used as an optical compensation sheet. Moreover, the polarizing plate of this invention is used advantageously for a liquid crystal display device. The polarizing plate of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-ferroelectric Liquid Crystal), OCB (Optically Compensatory Bend), STN (Supper Twisted Nematic), VA (Vertically Aligned) and Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed. Of these, the VA mode can be particularly preferably used.

In a VA mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle ), (3) Liquid crystal cells (n-ASM mode, CPA mode) in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied 58-59 (1998)) and (4) SURVAIVAL mode liquid crystal cells (announced at LCD International 98).
As shown in FIG. 2, the VA mode liquid crystal display device is composed of a liquid crystal cell (VA mode cell) and two polarizing plates (polarizing plate comprising TAC1, polarizer and TAC2) arranged on both sides thereof. Is mentioned. The liquid crystal cell carries liquid crystal between two electrode substrates, although not particularly shown.
In one aspect of the transmissive liquid crystal display device of the present invention, the protective film A is used as an optical compensation sheet, and one sheet is disposed between the liquid crystal cell and one polarizing plate, or both the liquid crystal cell and both polarizing plates. Place two in between.
In another aspect of the transmissive liquid crystal display device of the present invention, the protective film A is used as a protective film for a polarizing plate disposed between the liquid crystal cell and the polarizer. The protective film A may be used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, or two (between the liquid crystal cell and the polarizer) of both polarizing plates. The protective film A may be used for the protective film of the sheet. Preferably, one protective film A and one protective film B are used for the two protective films between the liquid crystal cell and the polarizer. In the bonding to the liquid crystal cell, the protective film A (preferably, the cellulose acylate film (TAC1)) of the polarizing plate of the present invention is preferably on the VA cell side. When the protective film A is used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, this is which side of the upper polarizing plate (observation side) or the lower polarizing plate (backlight side) But there is no functional problem. However, when used as an upper polarizing plate, it is necessary to provide a functional film on the observation side (upper side), and the production yield may be lowered. It is considered an embodiment.
And what formed both the light source side and observer side of FIG. 2 with the polarizing plate of this invention is the liquid crystal display device of a 2nd form, and what formed only the light source side with the polarizing plate of this invention is 3rd. It is a liquid crystal display device of a form.
The protective film (TAC2) in FIG. 2 may be a normal cell rate acylate film, and is preferably thinner than the protective film A. For example, 15 to 65 μm is preferable, and examples include, but are not limited to, commercially available KC4UX2M (40 μm manufactured by Konica Capto Corporation), KC5UX (60 μm manufactured by Konica Captor Corporation), and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to an Example.

[Example 1: Film formation of cellulose acylate film by band casting machine (films 1 to 23)]
(1) Cellulose acylate Cellulose acylates having different kinds of acyl groups and different degrees of substitution described in Tables 1 and 2 were prepared. This was carried out by adding sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) as a catalyst, adding carboxylic acid as a raw material for the acyl substituent, and carrying out an acylation reaction at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. Moreover, it age | cure | ripened at 40 degreeC after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone. In the table, CAB is an abbreviation for cellulose acetate butyrate (cellulose ester derivative in which an acyl group is an acetate and a butyryl group), and CAP is cellulose acetate propionate (an acyl group is an acetate group and a propionyl group). CTA means cellulose triacetate (cellulose ester derivative in which an acyl group is composed only of an acetate group).

(2) Dissolution <1-1> Cellulose acylate solution The following composition was put into a mixing tank, stirred to dissolve each component, further heated to 90 ° C. for about 10 minutes, then filtered with an average pore diameter of 34 μm and an average It filtered with the sintered metal filter with the hole diameter of 10 micrometers.

―――――――――――――――――――――――――――――――――
Cellulose acylate solution ――――――――――――――――――――――――――――――――――
Cellulose acylate 100.0 parts by mass Triphenyl phosphate (TPP) 8.0 parts by mass Biphenyl diphenyl phosphate (BDP) 4.0 parts by mass Methylene chloride 403.0 parts by mass Methanol 60.2 parts by mass ――――――――――――――――――――――――――――

<1-2> Matting Agent Dispersion Solution Next, the following composition containing the cellulose acylate solution prepared by the above method was charged into a dispersing machine to prepare a matting agent dispersion.

――――――――――――――――――――――――――――――――――
Matting agent dispersion ――――――――――――――――――――――――――――――――――
Silica particles having an average particle diameter of 16 nm (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd. 2.0 parts by mass Methylene chloride 72.4 parts by mass Methanol 10.8 parts by mass Cellulose acylate solution 10.3 parts by mass ―――――――――――――――――――――――――――

<1-3> Additive Solution Next, the following composition containing the cellulose acylate solution prepared by the above method was charged into a mixing tank and dissolved by stirring while heating to prepare an additive solution.

―――――――――――――――――――――――――――――――――
Additive solution ―――――――――――――――――――――――――――――――――
UV1 and UV2 20.0 parts by weight Methylene chloride 58.3 parts by weight Methanol 8.7 parts by weight Cellulose acylate solution 12.8 parts by weight ――――――――――――――――――― ―――――――――――――

100 parts by weight of the cellulose acylate solution, 1.35 parts by weight of the matting agent dispersion, and an amount of UV1 added to the cellulose acylate film of 0.7 and UV2 added to 0.3 The additive solution was mixed to prepare a dope for film formation. The addition ratio of the additive is shown in parts by mass when the amount of cellulose acylate is 100 parts by mass.
As for cellulose acylate films 2 to 23, cotton and additives were changed as described in Tables 1 and 2 to prepare the above solutions and dispersions.
Here, the abbreviations of the additives and plasticizers listed in Tables 1 and 2 are as follows. (TPP: triphenyl phosphate, BDP: biphenyl diphenyl phosphate), UV absorber (UV1: 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole), UV 2: 2 ( 2'-hydroxy-3 ', 5'-di-amylphenyl) -5-chlorobenzotriazole).
Retardation expression agent (1)

  Retardation expression agent (2)

The above dope was cast using a band casting machine. The film stripped from the band with the residual solvent amount described in Tables 1 and 2 was stretched in the longitudinal direction at the stretch ratio described in Tables 1 and 2 in the section from stripping to the tenter, and then using the tenter, Table 1 And stretched in the width direction at the stretch ratio described in 2, and immediately after transverse stretching, contracted (relaxed) in the width direction at the ratio described in Tables 1 and 2, and then released from the tenter to produce a cellulose acylate film. Filmed. The amount of residual solvent in the film when the tenter was removed was as shown in Tables 1 and 2. Both ends were cut off in front of the winding part to make a width of 2000 mm and wound up as a roll film having a length of 4000 m. Table 1 shows the draw ratio. About the produced cellulose acylate film (optical compensation sheet), Re retardation value and Rth retardation value at a wavelength of 590 nm were measured at 25 ° C. and 60% RH. Here, the results are shown in Table 1. In the film of the present invention, Rth (λ) was calculated with an average refractive index of 1.48.
Further, haze, film thickness unevenness, machine direction elastic modulus, and hygroscopic expansion coefficient of the produced cellulose acylate films 1 to 23 were measured. The results are shown in the column of “Liquid crystal cell side protective film” in Tables 3 and 4.

The secondary average particle size of the matting agent of the film obtained in this example was 1.0 μm or less, and the mass change when left standing at 80 ° C. and 90% RH for 48 hours was 0 to 3%. It was. Moreover, the dimensional change when it left still for 24 hours on the conditions of 60 degreeC95% RH and 90 degreeC5% RH was 0 to 4.5%. Further, all the samples had a photoelastic coefficient of 50 × 10 ⁻¹³ cm ² / dyne or less.

[Example 2: Production of protective film with antireflection function (films A to E)]
(Preparation of coating solution for light scattering layer)
50 g of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (PETA, manufactured by Nippon Kayaku Co., Ltd.) was diluted with 38.5 g of toluene. Further, 2 g of a polymerization initiator (Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) was added and mixed and stirred. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.51.
Further, a 30% toluene dispersion of crosslinked polystyrene particles having an average particle size of 3.5 μm (refractive index: 1.60, SX-350, manufactured by Soken Chemical Co., Ltd.) dispersed in this solution for 20 minutes at 10,000 rpm with a Polytron disperser. Add 13.3 g of 30% toluene dispersion of 1.7 g and crosslinked acrylic-styrene particles having an average particle size of 3.5 μm (refractive index 1.55, manufactured by Soken Chemical Co., Ltd.), and finally, fluorine-based surface modification 0.75 g of agent (FP-1) and 10 g of silane coupling agent (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to obtain a finished solution.
The liquid mixture was filtered through a polypropylene filter having a pore size of 30 μm to prepare a light scattering layer coating solution.

(Preparation of coating solution for low refractive index layer)
First, sol solution a was prepared as follows. A stirrer, a reactor equipped with a reflux condenser, 120 parts of methyl ethyl ketone, 100 parts of acryloyloxypropyltrimethoxysilane (KBM5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts of diisopropoxyaluminum ethyl acetoacetate were added and mixed. 30 parts of ion-exchanged water was added and reacted at 60 ° C. for 4 hours, and then cooled to room temperature to obtain sol solution a. The mass average molecular weight was 1600, and among the components higher than the oligomer component, the component having a molecular weight of 1000 to 20000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.
Thermally crosslinkable fluorine-containing polymer having a refractive index of 1.42 (JN-7228, solid content concentration 6%, manufactured by JSR Corporation) 13 g, silica sol (silica, MEK-ST particle size difference, average particle size 45 nm, solid content Concentration 30%, manufactured by Nissan Chemical Co., Ltd.) 1.3 g, 0.6 g of sol solution a prepared as described above, 5 g of methyl ethyl ketone, and 0.6 g of cyclohexanone were added. Thus, a coating solution for a low refractive index layer was prepared.

(Preparation of transparent protective film with antireflection layer)
An 80 μm-thick triacetyl cellulose film (Fujitac TD80UL, manufactured by Fuji Photo Film Co., Ltd.) is unwound in a roll form, and the above functional layer (light scattering layer) coating solution has a line number of 180 lines / inch and a depth. Using a microgravure roll with a diameter of 50 mm and a doctor blade having a gravure pattern of 40 μm, coating was performed under the conditions of a gravure roll rotation speed of 30 rpm and a conveyance speed of 30 m / min, drying at 60 ° C. for 150 seconds, and further under nitrogen purge Using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.), the coating layer is cured by irradiating ultraviolet rays with an illuminance of 400 mW / cm ² and an irradiation amount of 250 mJ / cm ² , and a functional layer having a thickness of 6 μm And wound up.
The triacetylcellulose film coated with the functional layer (light scattering layer) is unwound again, and the prepared coating liquid for low refractive index layer is gravure with a line number of 180 lines / inch and a depth of 40 μm on the light scattering layer side. Using a micro gravure roll with a diameter of 50 mm and a doctor blade having a pattern, it is applied under the conditions of a gravure roll rotation speed of 30 rpm and a conveyance speed of 15 m / min, dried at 120 ° C. for 150 seconds, and further dried at 140 ° C. for 8 minutes. Then, using a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) under a nitrogen purge, ultraviolet rays with an illuminance of 400 mW / cm ² and an irradiation amount of 900 mJ / cm ² were irradiated, and a low refraction of 100 nm thickness was achieved. A rate layer was formed, wound up, and a protective film with antireflection function (film A) was produced. The elastic modulus in the machine direction and the hygroscopic expansion coefficient of the produced protective film with antireflection function (film A) were measured. The results are shown in the column of “Protective film opposite to liquid crystal cell” in Tables 3 and 4.
The cellulose acylate film was changed from Fujitac TD80UL to the following, and films B to E with antireflection layers were produced in the same manner as film A.

Film B: KC4UX2M (manufactured by Konica Minolta Opto)
Film C: Film 22
Film D: Fujitac T40UZ (Fuji Photo Film Co., Ltd.)
Film E: KC8UX2M (manufactured by Konica Minolta Opto)

[Example 3]
(Preparation of polarizing plate)
A polyvinyl alcohol (PVA) film having a thickness of 80 μm is dyed by immersing it in an aqueous iodine solution having an iodine concentration of 0.05% by mass at 30 ° C. for 60 seconds, and then in an aqueous boric acid solution having a boric acid concentration of 4% by mass. The film was vertically stretched to 5 times the original length while being immersed for 2 seconds, and then dried at 50 ° C. for 4 minutes to obtain a polarizing film having a thickness of 20 μm.
The protective film and the commercially available cellulose acylate prepared in Examples 1 and 2 shown in Tables 1 and 2 and the cellulose acylate film on which the functional film was formed were placed in a sodium hydroxide aqueous solution at 1.5 mol / liter and 55 ° C. Then, the sodium hydroxide was thoroughly washed away with water. Then, after being immersed in a diluted sulfuric acid aqueous solution at 0.005 mol / liter at 35 ° C. for 1 minute, it was immersed in water to sufficiently wash away the diluted sulfuric acid aqueous solution. Finally, the sample was thoroughly dried at 120 ° C.
The protective film prepared in Examples 1 and 2 subjected to the saponification treatment as described above, the commercially available cellulose acylate, and the cellulose acylate film on which the functional film is formed are combined in the combinations shown in Tables 3 and 4 as the polarizing film. A polarizing plate 1 to 56 was obtained using a polyvinyl alcohol-based adhesive so as to sandwich the film.
Here, as a commercially available cellulose acylate film, Fujitac T40UZ (manufactured by Fuji Photo Film Co., Ltd., haze 0.3%, thickness unevenness 0.6 μm), Fujitac TD80UL (manufactured by Fuji Photo Film Co., Ltd., haze 0.3%) , Thickness variation 0.7 μm), and KC4UX2M (Konica Minolta Opto Co., Ltd., haze 0.4%, thickness variation 0.6 μm), KC8UX2M (Konica Minolta Opto Co., Ltd., haze 0.4%, thickness variation) 0.6 μm) was used. For these commercially available cellulose acylate films, the elastic modulus and hygroscopic expansion coefficient in the machine direction (MD) were also measured. The results are shown in the column of “Protective film opposite to liquid crystal cell” in Tables 3 and 4.
At this time, since the polarizing film and the protective films on both sides of the polarizing film are produced in a roll form, the longitudinal directions of the roll films are parallel to each other and are continuously bonded. As shown in FIG. 3, in the protective film disposed on the cell side, the transmission axis of the polarizer and the slow axis of the cellulose acylate film produced in Examples 1 and 2 are parallel.
An acrylic adhesive material was attached to the cell side surface of the polarizing plate prepared above, and a separate film was attached on the adhesive material. A protective film was attached to the surface opposite to the cell.

[Example 4]
Using a spectrophotometer (manufactured by JASCO Corporation), in the wavelength region of 380 to 780 nm, the spectral reflectance at an incident angle of 5 ° is measured from the functional film side, and the integrating sphere average reflectance of 450 to 650 nm is obtained. When it calculated | required, it was 2.3% in the polarizing plates 17-30 and 45-56 which used the film AE which is a transparent protective film with an antireflection layer. Here, the protective film on the transparent protective film with the antireflection layer was peeled off, and the reflectance was measured.

[Example 5]
(Measurement of curl)
The polarizing plates 1 to 56 produced in Example 3 were punched into a rectangular shape in which the absorption axis direction of the polarizing plate was 305 mm and the transmission axis direction of the polarizing plate was 230 mm. Place the surface where the end is raised on a flat table and leave it in an environment of 25 ° C and 60% RH for 2 hours or more. I measured it.
Here, the case where it becomes concave on the surface (adhesive coating surface) side to be attached to the liquid crystal cell is called + (plus) curl, and the case where it becomes convex is called-(minus) curl. The results are shown in Tables 3 and 4.

(Polarizing plate adhesion test)
The polarizing plate punched out above was set in a polarizing plate pasting machine, and a test was performed in which the polarizing plate was pasted on a 0.7 mm thick glass plate. For a polarizing plate with a curl of -30 to +15 mm, there is no floating on the attaching jig with a suction mechanism of the attaching machine, generation of bubbles after attaching the glass plate, and no deviation of the side of the polarizing plate with respect to the side of the glass plate. It was.
On the other hand, with a polarizing plate with a curl of more than +15 mm, a gap is generated between the sticking jig with the sticking mechanism of the sticking machine and the central part of the polarizing plate, and the polarizing plate can be stably sucked and fixed with the sticking jig. Without sticking to the glass plate, falling from the polarizing plate attaching jig, generation of bubbles between the polarizing plate and the glass plate, and deviation of the attaching angle occurred. In addition, with a polarizing plate with a curl of more than −30 mm, a gap is generated between the sticking jig with the sticking mechanism of the sticking machine and the periphery of the polarizing plate, and the polarizing plate can be stably sucked and fixed with the sticking jig. Without sticking to the glass plate, falling from the polarizing plate attaching jig, generation of bubbles between the polarizing plate and the glass plate, and deviation of the attaching angle occurred.

[Example 6]
(Attaching a polarizing plate to the panel)
Attaching a polarizing plate to a VA panel Table 5 shows the polarizing plate produced in Example 3 by peeling off the front and back polarizing plates and retardation plate of a VA mode liquid crystal TV (LC-37GE2, manufactured by Sharp Corporation). This was punched in a 37-inch size and pasted on a liquid crystal cell. In this case, the absorption axis of the polarizing plate on the viewing side is in the horizontal direction of the panel, the absorption axis of the polarizing plate on the backlight side is in the vertical direction of the panel, and the adhesive material surface is on the liquid crystal cell side.

[Measurement of front contrast of liquid crystal display]
After removing the protective film, using a measuring machine (BM5A, manufactured by TOPCON), measure the luminance value of black display and white display in the normal direction of the panel in the dark room, and determine the front contrast (white luminance / black luminance). Calculated. The results are shown in Table 5.

It is sectional drawing which shows typically the cross-section of the polarizing plate of this invention. It is sectional drawing which shows typically the cross-section of the liquid crystal display device of this invention. It is a schematic diagram which shows the bonding method of the cellulose acylate film at the time of manufacture of the polarizing plate of this invention.

Claims (25)

  A polarizing plate in which a protective film A is bonded to at least one of the polarizing films, the protective film A having a thickness of 20 to 70 μm, and a curl amount at 25 ° C. and 60% RH in a range of −30 mm to +15 mm. There is a polarizing plate. The thickness d1 and elastic modulus E1 of the protective film A and the thickness d2 and elastic modulus E2 of the protective film B disposed on the opposite side of the polarizing film satisfy the following formula (III): Item 10. A polarizing plate according to item 1.
Formula (III): 0.5 × E1 × d1 ≦ E2 × d2 ≦ 1.2 × E1 × d1 The polarizing plate according to claim 1, wherein the hygroscopic expansion coefficient C1 of the protective film A and the hygroscopic expansion coefficient C2 of the protective film B satisfy the following mathematical formula (IV).
Formula (IV): 0.3 × C1 ≦ C2 ≦ 1.3 × C1 The thickness d1, the elastic modulus E1, and the hygroscopic expansion coefficient C1 of the protective film A, and the thickness d2, the elastic modulus E2, and the hygroscopic expansion coefficient C2 of the protective film B disposed on the opposite side of the polarizing film are expressed by the following formula ( V) is satisfy | filled, The polarizing plate in any one of Claims 1-3 characterized by the above-mentioned.
Formula (V): −30 ≦ {(E2 × d2) / (E1 × d1) −1} × 60 + (C2 / C1-1) × 10 ≦ 15 The polarizing plate according to claim 1, wherein Re (λ) and Rth (λ) of the protective film A satisfy the following formulas (VII) and (VIII).
Formula (VII): 20 nm ≦ Re (590) ≦ 200 nm
Formula (VIII): 60 nm ≦ Rth (590) ≦ 400 nm
[In the formula, Re (λ) is a front retardation value (unit: nm) at a wavelength λnm, and Rth (λ) is a retardation value (unit: nm) in a film thickness direction at a wavelength λnm. ]   The polarizing plate according to claim 1, wherein a haze value of at least one of the protective film A and the protective film B is 1.0% or less.   The polarizing plate according to claim 1, wherein the thickness unevenness of the protective film A is 0.5 μm or less.   The polarizing plate according to claim 1, wherein the protective film A has an elastic modulus of 3 to 6 GPa. The protective film A is a film consisting essentially of cellulose acylate obtained by substituting the hydroxyl group of the glucose unit constituting cellulose with an acyl group having 2 or more carbon atoms, and the glucose unit constituting cellulose When the substitution degree of the 2-position hydroxyl group with an acyl group is DS2, the substitution degree of the 3-position hydroxyl group with an acyl group is DS3, and the substitution degree of the 6-position hydroxyl group with an acyl group is DS6, the following formula (XI) is obtained: The polarizing plate according to claim 1, wherein the polarizing plate is formed by using a cellulose acylate to be filled.
Formula (XI): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0 The polarizing plate according to claim 9, wherein the protective film A is formed using cellulose acylate satisfying the following formula (XII).
Formula (XII): DS6 / (DS2 + DS3 + DS6) ≧ 0.315 The polarizing plate according to claim 9 or 10, wherein the acyl group is an acetyl group. The protective film A is a cellulose acylate film substantially composed of cellulose acylate which is a mixed fatty acid ester of cellulose in which a hydroxyl group of cellulose is substituted with an acetyl group and an acyl group having 3 or more carbon atoms,
Substitution degrees DS2A, DS3A, DS6A of acetyl groups at the 2nd, 3rd, 6th positions of the cellulose acylate and substitution degrees DS2B, DS3B of acyl groups having 3 or more carbon atoms at the 2nd, 3rd, 6th positions DS6B satisfies the following formula (XIII), and at least one of DS2B, DS3B, DS6B is formed using cellulose acylate having a positive value. The polarizing plate as described in.
Formula (XIII): 2.0 ≦ DS2A + DS2B + DS3A + DS3B + DS6A + DS6B ≦ 3.0   The polarizing plate according to claim 12, wherein the acyl group having 3 or more carbon atoms is a butanoyl group.   The polarizing plate according to claim 12, wherein the acyl group having 3 or more carbon atoms is a propionyl group. The substitution degree of the acetyl group of the cellulose acylate at the 2nd, 3rd and 6th positions and the substitution degree B of the acyl group having 3 or more carbon atoms satisfy the following formula (XIV). The polarizing plate in any one of -14.
Formula (XIV): (DS6A + DS6B) / (DS2A + DS2B + DS3A + DS3B + DS6A + DS6B) ≧ 0.315   The polarizing plate according to claim 1, wherein the protective film A contains one or more retardation enhancers of a rod-shaped compound or a disk-shaped compound.   The said protective film A contains 1 or more types selected from the plasticizer, the ultraviolet absorber, the peeling accelerator, the dye, and the mat agent, The any one of Claims 1-16 characterized by the above-mentioned. Polarizer.   A liquid crystal display device comprising a liquid crystal cell and a polarizing plate disposed on at least one of both surfaces of the liquid crystal cell, wherein the polarizing plate is the polarizing plate according to claim 1.   The liquid crystal display device according to claim 18, wherein a polarizing plate is disposed so that the protective film A is on the liquid crystal display device side.   The liquid crystal display device according to claim 18, wherein the liquid crystal cell is in a vertical alignment mode.   It is a manufacturing method of the protective film used for the polarizing plate of Claims 1-17, Comprising: It biaxially stretches by the stretch ratio of 10 to 60% in the Y direction orthogonal to a X direction 30 to 100% and a X direction. A method for producing a protective film.   It is a manufacturing method of the protective film used for the polarizing plate of Claims 1-17, Comprising: At least one direction extending | stretching of the X direction and the Y direction is biaxially stretched by the extending | stretching speed of 70-200% / min, It is characterized by the above-mentioned. A method for manufacturing a protective film. It is a manufacturing method of the protective film used for the polarizing plate of Claims 1-17, Comprising: Film surface temperature at the time of extending | stretching at least one direction is 130-180 degreeC among X direction and Y direction, It is characterized by the above-mentioned. A method for manufacturing a protective film.   A method for producing a protective film for use in the polarizing plate according to claim 1, wherein the residual solvent amount at the time of peeling from the support is 50 to 100% by mass.   It is a manufacturing method of the protective film used for the polarizing plate of Claims 1-17, Comprising: The residual solvent amount at the time of completion | finish of biaxial stretching of a X direction and a Y direction is 15-30 mass%, Manufacturing method.

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