JP2006195364A - Liquid crystal display, optical compensation sheet used for the same, and polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a TN liquid crystal display wherein visual confirmation of a display content can be suppressed even when a third person except an user looks in the liquid crystal display from a near side, only the user can visually confirm the display content and security and privacy can be maintained, to provide an optical compensation sheet used therefor and to provide a polarizing plate. <P>SOLUTION: In the liquid crystal display having a liquid crystal cell of a TN (twisted nematic) alignment mode and a pair of polarizing plates disposed on both sides of the liquid crystal cell, the optical compensation sheet is disposed between a polarizing film of at least one polarizing plate and the liquid crystal cell and the optical compensation sheet has at least a transparent film (1) satisfying following formulas (1) and (2) and an optically anisotropic layer (2) comprising a liquid crystalline compound and formed by application. Formula (1): 0≤Re<SB>630</SB>≤10 and ¾Rth<SB>630</SB>¾≤25 and formula (2): ¾Re<SB>400</SB>-Re<SB>700</SB>¾≤10 and ¾Rth<SB>400</SB>-Rth<SB>700</SB>¾≤35, wherein Re<SB>λ</SB>denotes a front retardation value (unit:nm) in the wavelength λ nm and Rth<SB>λ</SB>denotes a retardation value (unit: nm) in the film thickness direction in the wavelength λ nm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, an optical compensation sheet used therefor, and a polarizing plate.

The liquid crystal display device is composed of a polarizing plate and a liquid crystal cell.
In a TN mode TFT liquid crystal display device which is currently mainstream, an optical compensation sheet is inserted between the polarizing plate and the liquid crystal cell to realize a liquid crystal display device with high display quality (see, for example, Patent Document 1).

  Although the liquid crystal display device is usually limited to a certain viewing angle, the display can be visually recognized by all the eyes within the viewing angle. That is, a plurality of people can simultaneously view the display of one liquid crystal display device at a time. The tendency is becoming remarkable by the recent wide viewing angle countermeasure technology improved as in Patent Document 1.

  In particular, the viewing angle characteristics of the TN liquid crystal display have been remarkably improved in recent years, and the display can be seen by a person in a certain viewing angle range.

  This is very convenient in that the display can always be correctly viewed even if the user changes the viewing position slightly, but on the other hand, the content being displayed can be seen by others. There are also security and privacy issues. For example, when a company employee looks at the display of a portable information terminal outside the office, such as in a train, where someone else is in the immediate vicinity, and when it is an important confidential e-mail, etc. It may be difficult to open and view emails. In addition, there are cases in which display content that is not a problem in terms of confidentiality may not be viewed by others.

  On the other hand, as a technology for security measures, a head-mounted display and a spectacle-type display have been proposed. The head mounted display is a goggle type display device. When the user wears the head mounted display on the head, only the user can see the display on the small liquid crystal display inside, and other people cannot see it. However, at present, this type of device is bulky and has a bad appearance and is relatively heavy, so that the feeling of use is not comfortable, and the surroundings cannot be seen at all during wearing.

The eyeglass-type display has problems such as an increase in cost for reducing the size of the display itself, a decrease in resolution, an expensive optical system, and a short focal distance, so that the user is very tired.
JP-A-8-50206

  The object of the present invention is to suppress the viewing of display contents even when a third party other than the user looks in the vicinity, so that only the user can view the display, and security and privacy can be maintained. It is to provide a TN liquid crystal display device.

  By the research of the present inventors, the optical properties of the transparent film are specially controlled, and an optical compensation sheet having an optically anisotropic layer formed containing a liquid crystal compound is used, so that only the user can use the TN liquid crystal display device. As a result, an optical compensation sheet capable of visually recognizing the above was obtained.

  That is, according to the present invention, an optical compensation sheet, a polarizing plate, and a liquid crystal display device having the following configuration are provided, and the above-described problems of the present invention are achieved.

<1> A liquid crystal display device having a TN (twisted nematic) alignment mode liquid crystal cell and a pair of polarizing plates disposed on both sides of the liquid crystal cell,
An optical compensation sheet is disposed between the polarizing film of at least one polarizing plate and the liquid crystal cell,
The optical compensation sheet is
(1) a transparent film that satisfies the following mathematical formulas (1) and (2);
(2) an optically anisotropic layer containing a liquid crystalline compound and formed by coating;
And at least a liquid crystal display device.
Formula (1): 0 ≦ Re ₆₃₀ ≦ 10 and | Rth ₆₃₀ | ≦ 25
Formula (2): | Re ₄₀₀ −Re ₇₀₀ | ≦ 10 and | Rth ₄₀₀ −Rth ₇₀₀ | ≦ 35
[In the formula, Re _λ is a front retardation value (unit: nm) at a wavelength _λ nm, and Rth _λ is a retardation value (unit: nm) in a film thickness direction at a wavelength _λ nm. ]
<2> The liquid crystal display device according to <1>, wherein the transparent film is a cellulose acylate film.
<3> The liquid crystal display device according to <1> or <2>, wherein the liquid crystal compound is a discotic liquid crystal compound.
<4> The above <1> to <3, wherein the transparent film contains at least one compound that decreases the retardation value (Rth _λ ) in the film thickness direction in a range that satisfies the following mathematical formulas (3) and (4). > The liquid crystal display device according to any one of the above.
Formula (3): (Rth _λA −Rth _λ0 ) /A≦−1.0
Formula (4): 0.01 ≦ A ≦ 30
here,
Rth _.lambda.A: Rth compounds that reduce the _lambda Rth of film containing A mass% _{λ (nm),}
Rth _.lambda.0: Rth of the film not containing the compound decreasing the Rth λ λ _(nm),
A: The mass (%) of the compound that reduces Rth _λ when the mass of the film raw material polymer is 100,
It is.
<5> The cellulose acylate film is a film comprising cellulose acylate having an acyl substitution degree of 2.85 to 3.00, and the cellulose acylate film comprises a compound that decreases Re _λ and Rth _λ. The liquid crystal display device according to any one of <2> to <4>, wherein 0.01 to 30% by mass based on the solid content of at least one cellulose acylate.
<6> The cellulose acylate film contains 0.01 to 30% by mass of at least one compound that reduces | Re ₄₀₀ -Re ₇₀₀ | and | Rth ₄₀₀ -Rth ₇₀₀ | with respect to the solid content of cellulose acylate. The liquid crystal display device according to any one of <2> to <5>.
<7> The liquid crystal display device according to any one of <1> to <6>, wherein the transparent film has a thickness of 10 to 120 μm.
<8> An optical compensation sheet used for the liquid crystal display device according to any one of <1> to <7>.
<9> A polarizing plate comprising the optical compensation sheet according to <8> as a protective film on at least one surface.
<10> (1) A cellulose acylate film satisfying the following mathematical formulas (1) and (2);
(2) an optically anisotropic layer containing a liquid crystalline compound and formed by coating;
And at least an optical compensation sheet.
Formula (1): 0 ≦ Re ₆₃₀ ≦ 10 and | Rth ₆₃₀ | ≦ 25
Formula (2): | Re ₄₀₀ −Re ₇₀₀ | ≦ 10 and | Rth ₄₀₀ −Rth ₇₀₀ | ≦ 35
[In the formula, Re _λ is a front retardation value (unit: nm) at a wavelength _λ nm, and Rth _λ is a retardation value (unit: nm) in a film thickness direction at a wavelength _λ nm. ]
<11> A polarizing plate having the optical compensation sheet according to <10> as a protective film on at least one surface.

  The optical compensation sheet of the present invention has a transparent film with specially controlled optical properties and an optically anisotropic layer formed containing a liquid crystalline compound, and by using this optical compensation sheet for a liquid crystal display device, Only the user can view the liquid crystal display device. The liquid crystal display device of the present invention does not cause a problem when the above-described head mounted display or eyeglass type display is used. The optical compensation sheet and the polarizing plate using the optical compensation sheet as a protective film can be advantageously used for a TN (Twisted Nematic) type liquid crystal display device.

<Optical compensation sheet>
The optical compensation sheet of the present invention has a transparent film and an optically anisotropic layer formed from a liquid crystalline compound.

[Measurement of optical anisotropy (Re, Rth)]
In the present specification, Re _λ and Rth _λ respectively represent the retardation in the front direction and the retardation in the film thickness direction at the wavelength λ. Re _λ is measured using “KOBRA 21ADH” (manufactured by Oji Scientific Instruments) with light having a wavelength of λ nm incident in the normal direction of the film. Rth _λ is a wavelength of λ nm from a direction inclined by + 40 ° with respect to the normal direction of the film, with Re _λ and an in-plane slow axis (determined by “KOBRA 21ADH”) as an inclination axis (rotation axis) Retardation value measured by making it incident, and retardation measured by making light of wavelength λ nm incident from a direction inclined by −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis) “KOBRA 21ADH” is calculated based on the retardation value measured in a total of three directions, the assumed value of the average refractive index, and the input film thickness value.

Here, as the assumed value of the average refractive index, the values of “Polymer Handbook” (“John Wiley & Sons, Inc.) and catalogs of various optical films can be used. The value of the average refractive index of the main optical film can be exemplified by the following:
Cellulose acylate film (1.48), cycloolefin polymer film (1.52), polycarbonate film (1.59), polymethyl methacrylate film (1.49), polystyrene film (1.59).

  Further, in the present specification, “substantially parallel” and “substantially orthogonal” mean that the angle is within a range of ± 5 ° less than a strict angle. This range is preferably less than ± 4 °, more preferably less than ± 3 °, and most preferably less than ± 2 °.

<Transparent film>
[Optical properties of transparent film]
The retardation of the transparent film used in the present invention needs to be small, specifically satisfy the following formula (1).
Formula (1): 0 ≦ Re ₆₃₀ ≦ 10 and | Rth ₆₃₀ | ≦ 25
In the above formula (1), preferably,
Formula (1-1): 0 ≦ Re ₆₃₀ ≦ 5 and | Rth ₆₃₀ | ≦ 20
And more preferably
Formula (1-2): 0 ≦ Re ₆₃₀ ≦ 3 and | Rth ₆₃₀ | ≦ 15
It is.
Here, Re ₆₃₀ is the front retardation value (unit: nm) at a wavelength of 630 nm, and Rth ₆₃₀ is the retardation value (unit: nm) in the film thickness direction at a wavelength of 630 nm.

  When a cellulose acylate film is used as a transparent film, particularly a transparent film, the optical anisotropy is sufficiently reduced by using a compound that suppresses the cellulose acylate from being oriented in the front direction and the film thickness direction, and Re and Rth are Both are preferably close to zero.

Moreover, the wavelength dispersion of the transparent film used for this invention needs to be small, specifically to satisfy | fill following Numerical formula (2).
Formula (2): | Re ₄₀₀ −Re ₇₀₀ | ≦ 10 and | Rth ₄₀₀ −Rth ₇₀₀ | ≦ 35
In the above formula (2), preferably
Formula (2-1): | Re ₄₀₀ −Re ₇₀₀ | ≦ 5 and | Rth ₄₀₀ −Rth ₇₀₀ | ≦ 25
And more preferably
Formula (2-2): | Re ₄₀₀ −Re ₇₀₀ | ≦ 3 and | Rth ₄₀₀ −Rth ₇₀₀ | ≦ 15
It is.
Here, Re _λ is the front retardation value at wavelength _λ nm (unit: nm), Rth _λ is the retardation value in the film thickness direction at wavelength _λ nm (unit: nm) (for example, Re ₄₀₀ and Rth ₄₀₀ are front values at wavelength 400 nm) And the retardation value in the film thickness direction).

Using a compound capable of controlling the wavelength dispersion of Re _λ and Rth _λ of the film by absorbing in the ultraviolet region of a wavelength of 200 to 400 nm for the transparent film, the difference between Re and Rth at wavelengths of 400 nm and 700 nm, | Re ₄₀₀ − It is preferable to reduce Re ₇₀₀ | and | Rth ₄₀₀ −Rth ₇₀₀ |.

[Transparent film]
As a transparent film, if it is a transparent film which satisfies the said Numerical formula (1) and Numerical formula (2), it can use without a restriction | limiting especially. A transparent polymer film is preferable as the transparent film, and as the polymer, cellulose acylate, norbornene polymer, polycarbonate, polystyrene, polyvinyl alcohol, polyethylene, or polypropylene can be used.
10-120 micrometers is preferable, as for the thickness of a transparent film, 20-100 micrometers is more preferable, and 30-90 micrometers is more preferable.

It is particularly preferable to use a cellulose acylate film as the transparent film. As the protective film of the polarizing plate, a cellulose acylate film is generally used. By using a cellulose acylate film as a transparent film of an optical compensation sheet which is a preferred embodiment of the optical compensation sheet of the present invention, the optical compensation film is used. When a sheet is used as one protective film of a polarizing plate, an optical compensation function can be added to the polarizing plate without increasing the number of components of the polarizing plate, which is preferable.
Hereinafter, the present invention will be described by taking as an example the case of using a cellulose acylate film as the transparent film.

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

(Degree of cellulose acylate substitution)
Next, the cellulose acylate produced from the above cellulose will be described. In the present invention, cellulose acylate is obtained by acylating a hydroxyl group of cellulose, and any substituent can be used from an acetyl group having 2 carbon atoms to an acyl group having 22 carbon atoms. The degree of substitution of cellulose with a hydroxyl group is not particularly limited, but the degree of substitution can be obtained by measuring the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted with a hydroxyl group of cellulose. As a measuring method, it can carry out according to ASTM D-817-91.

  As described above, in the cellulose acylate of the present invention, the substitution degree of the hydroxyl group of cellulose is not particularly limited, but the acyl substitution degree of the cellulose hydroxyl group is preferably 2.50 to 3.00. Furthermore, the substitution degree is preferably 2.60 to 3.00, and more preferably 2.65 to 3.00.

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

  Among the acyl substituents for substituting the hydroxyl group of the cellulose, when it is composed of at least two kinds substantially selected from acetyl group / propionyl group / butanoyl group, the total substitution degree is 2.50-3. In the case of 0.00, the optical anisotropy of the cellulose acylate film can be further reduced, which is preferable. A more preferable degree of acyl substitution is 2.60 to 3.00, and more desirably 2.65 to 3.00.

(Degree of polymerization of cellulose acylate)
The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average polymerization degree, and in cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. . If the degree of polymerization is not more than the upper limit, the viscosity of the cellulose acylate dope solution becomes high, and problems such as difficulty in film production due to casting do not occur. If the degree of polymerization is equal to or greater than the lower limit, it is preferable because there is no inconvenience such as a decrease in strength of the produced film. The average degree of polymerization can be measured by the intrinsic viscosity method of Uda et al. (Kazuo Uda, Hideo Saito, “Journal of Textile Society”, Vol. 18, No. 1, pages 105-120, 1962). This is also described in detail in JP-A-9-95538.

  The molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) is small, and the molecular weight A narrow distribution is preferred. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and most preferably 1.0 to 1.6. preferable.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent.

  In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within this range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. At the time of producing the cellulose acylate of the present invention, the water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly a cellulose acyl having a water content of 0.7% by mass or less. Rate. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In order to obtain the moisture content of the cellulose acylate in the present invention, it is necessary to dry, and the method is not particularly limited as long as the desired moisture content is obtained. These cellulose acylates of the present invention are described in detail on page 7 to page 12 of the raw material cotton and the synthesis method in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in.

  The cellulose acylate used in the present invention can be used by mixing two or more different types of cellulose acylates within the above-described ranges such as a substituent, a substitution degree, a polymerization degree, and a molecular weight distribution.

(Additive to cellulose acylate)
Hereinafter, preferred additives for use in the present invention will be described.
In the cellulose acylate solution of the present invention, various additives (for example, a compound that reduces optical anisotropy, a wavelength dispersion adjusting agent, an ultraviolet inhibitor, a plasticizer, a deterioration inhibitor, Fine particles, optical property modifiers, etc.) can be added and these are described below. Further, the addition may be performed at any time in the dope preparation step, but may be performed by adding a preparation step by adding an additive to the final preparation step of the dope preparation step.

In the present invention, it is desirable to contain at least one compound that reduces the optical anisotropy of the transparent film, particularly the retardation Rth in the film thickness direction, within the range satisfying the following mathematical formulas (3) and (4).
Formula (3): (Rth _λA −Rth _λ0 ) /A≦−1.0
Formula (4): 0.01 ≦ A ≦ 30
In the above formulas (3) and (4), more preferably,
Formula (3-1): (Rth _λA −Rth _λ0 ) /A≦−2.0
Formula (4-1): 0.05 ≦ A ≦ 25
And more preferably
Formula (3-2): (Rth _λA −Rth _λ0 ) /A≦−3.0
Formula (4-2): 0.1 ≦ A ≦ 20
It is.
_Here, Rth λA Rth λ _(nm) of the compound that reduces the Rth _lambda containing A mass% film, Rth _.lambda.0 the Rth of the film not containing the compound decreasing the Rth λ λ _(nm), A is a film material This is the mass (%) of the compound that reduces Rth _λ when the mass of the polymer is 100.
Hereinafter, the compound that decreases the retardation Rth in the film thickness direction will be described by way of example of a compound that decreases the optical anisotropy of the cellulose acylate film, but the present invention is not limited thereto.

(Structural characteristics of compounds that reduce the optical anisotropy of cellulose acylate film)
In order to sufficiently reduce the optical anisotropy and make both Re and Rth close to zero, a compound that inhibits the cellulose acylate in the film from being oriented in the front direction and the film thickness direction is used. It is preferable. In addition, the compound that reduces optical anisotropy is sufficiently compatible with cellulose acylate, and it is advantageous that the compound itself does not have a rod-like structure or a planar structure. Specifically, when a plurality of planar functional groups such as aromatic groups are provided, a structure having these functional groups in a non-planar rather than the same plane is advantageous.

(Log P value)
In preparing the cellulose acylate film used in the present invention, as described above, a compound that reduces the optical anisotropy by inhibiting the cellulose acylate in the film from being oriented in the front direction and the film thickness direction. Among them, it is preferable to select a compound having an octanol-water partition coefficient (log P value) of 0 to 7. A compound having a log P value of 7 or less is excellent in compatibility with cellulose acylate and does not cause inconveniences such as cloudiness and powder blowing of the film. A compound having a log P value of 0 or more is preferred because the hydrophilicity does not become too high and problems such as deterioration of the water resistance of the cellulose acetate film do not occur. A more preferable range for the logP value is 1 to 6, and a particularly preferable range is 1.5 to 5.

  The octanol-water partition coefficient (log P value) can be measured by a flask shaking method described in JIS Z-7260-107 (2000). Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement. As a calculation method, the Crippen's fragmentation method {“J. Chem. Inf. Compute. Sci.”, 27, p. 21 (1987)}, Viswanadhan's fragmentation method {“J. Chem. Inf. Compute. Sci.”, 29, p. 163 (1989)}, Broto's fragmentation method {“Eur. J. Med. Chem.-Chim. Theor.”, Vol. 19, p. 71 (1984)} is preferably used, but the Crippen's fragmentation method is more preferable. When the log P value of a certain compound differs depending on the measurement method or calculation method, it is determined by the Crippen's fragmentation method whether the compound is within the scope of the present invention.

(Physical properties of compounds that reduce optical anisotropy)
The compound that reduces optical anisotropy may or may not contain an aromatic group. Further, the compound that lowers the optical anisotropy preferably has a molecular weight of 150 or more and 3000 or less, more preferably 170 or more and 2000 or less, and particularly preferably 200 or more and 1000 or less. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.

  The compound that reduces optical anisotropy is preferably liquid at 25 ° C. or a solid having a melting point of 25 to 250 ° C., more preferably liquid at 25 ° C. or a melting point of 25 to 200 ° C. It is a solid. Moreover, it is preferable that the compound which reduces optical anisotropy does not volatilize in the process of dope casting for cellulose acylate film production and drying.

  The amount of the compound that reduces optical anisotropy is preferably 0.01 to 30% by mass, more preferably 1 to 25% by mass, and 5 to 20% by mass with respect to cellulose acylate. It is particularly preferred.

  The compound that decreases the optical anisotropy may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.

  The timing for adding the compound that decreases the optical anisotropy may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  The compound that reduces the optical anisotropy is such that the average content of the compound in the portion from the surface on at least one side to 10% of the total film thickness is the average content of the compound in the central portion of the cellulose acylate film. It is preferable that it is 80 to 99% of. The amount of the compound of the present invention can be determined, for example, by measuring the amount of the compound at the surface and the central portion by a method using an infrared absorption spectrum described in JP-A-8-57879.

  Specific examples of the compound that decreases the optical anisotropy of the cellulose acylate film include compounds of the general formulas (1) and (3), but the present invention is not limited to these compounds.

The compound of the general formula (1) will be described.
General formula (1):

In the general formula (1), R ¹¹ represents an alkyl group or an aryl group, and R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Further, it is particularly preferable that the total number of carbon atoms of R ¹¹ , R ¹² and R ¹³ is 10 or more.

  As the substituent, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group, and a sulfonamide group are preferable, and an alkyl group, an aryl group, an alkoxy group, a sulfone group, and a sulfonamide group are particularly preferable. Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 (E.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclooctyl, nonyl, adamantyl, decyl, t-octyl, undecyl, Dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred. As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, triphenylphenyl) are particularly preferable. Although the preferable example of a compound represented by General formula (1) is shown below, this invention is not limited to these specific examples.

Next, the compound of General formula (2) is demonstrated.
General formula (2):

In the formula, R ²¹ represents an alkyl group or an aryl group, and R ²² and R ²³ each independently represents a hydrogen atom, an alkyl group, or an aryl group.

  Although the preferable example of a compound represented by General formula (2) below is shown below, this invention is not limited to these specific examples.

(Wavelength dispersion adjusting agent)
Next, the compound for reducing the wavelength dispersion of the transparent film will be described by taking as an example a compound for reducing the wavelength dispersion of the cellulose acylate film (hereinafter also referred to as a wavelength dispersion adjusting agent), but the present invention is not limited thereto. Absent.

In order to improve the Rth wavelength dispersion of the cellulose acylate film of the present invention, a compound that reduces the Rth wavelength dispersion ΔRth = | Rth ₄₀₀ −Rth ₇₀₀ | represented by the following formula (5) (wavelength dispersion): It is desirable to contain at least one adjusting agent within a range satisfying the following mathematical formulas (6) and (7).
Formula (5): ΔRth = | Rth ₄₀₀ −Rth ₇₀₀ |
Formula (6): (ΔRth _B −ΔRth ₀ ) /B≦−2.0
Formula (7): 0.01 ≦ B ≦ 30
In the above formulas (6) and (7), more preferably,
Formula (6-1): (ΔRth _B −ΔRth ₀ ) /B≦−3.0
Formula (7-1): 0.05 ≦ B ≦ 25
And more preferably
Formula (6-2): (ΔRth _B −ΔRth ₀ ) /B≦−4.0
Formula (7-2): 0.1 ≦ B ≦ 20
It is.
Here, ΔRth _B is ΔRth (nm) of the film containing B mass% of the wavelength dispersion adjusting agent, Rth ₀ is ΔRth (nm) of the film not containing the wavelength dispersion adjusting agent, and B is 100 mass of the film raw material polymer. It is the mass (%) of the chromatic dispersion adjusting agent.

The wavelength dispersion adjusting agent is a compound having absorption in the ultraviolet region of 200 to ₄₀₀ nm and reducing | Re ₄₀₀ -Re ₇₀₀ | and | Rth ₄₀₀ -Rth ₇₀₀ | of the film. It is also possible to adjust the wavelength dispersion of Re and Rth of the cellulose acylate film by adding 0.01 to 30% by mass, preferably 0.1 to 30% by mass, based on one type of cellulose acylate solid content. This is a preferred embodiment of the present invention.

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

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

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

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

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

(Addition amount of wavelength dispersion adjusting agent)
The added amount of the wavelength dispersion adjusting agent preferably used in the present invention is preferably 0.01 to 30% by mass, more preferably 0.1 to 30% by mass with respect to cellulose acylate. 0.2 to 10% by mass is particularly preferable.

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

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

As the benzotriazole-based compound, those represented by the following general formula (3) are preferably used as the wavelength dispersion adjusting agent of the present invention.
Formula ^{(3): Q 1 -Q 2} -OH
(In the formula, Q ¹ represents a nitrogen-containing aromatic heterocycle, and Q ² represents an aromatic ring.)

Q ¹ represents a nitrogen-containing aromatic heterocycle, preferably a 5- to 7-membered nitrogen-containing aromatic heterocycle, more preferably a 5- to 6-membered nitrogen-containing aromatic heterocycle, such as imidazole, Pyrazole, triazole, tetrazole, thiazole, oxazole, selenazole, benzotriazole, benzothiazole, benzoxazole, benzoselenazole, thiadiazole, oxadiazole, naphthothiazole, naphthoxazole, azabenzimidazole, purine, pyridine, pyrazine, pyrimidine, pyridazine , Triazine, triazaindene, tetrazaindene and the like, more preferably a 5-membered nitrogen-containing aromatic heterocycle, specifically imidazole, pyrazole, triazole, tetrazole, thiazole, oxazole, Benzotriazole, benzothiazole, benzoxazole, thiadiazole, oxadiazole preferably, particularly preferably benzotriazole.

The nitrogen-containing aromatic heterocycle represented by Q ¹ may further have a substituent, and the substituent T described below can be applied as the substituent. In addition, when there are a plurality of substituents, each may be condensed to form a ring.

The aromatic ring represented by Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring or a naphthalene ring), and more preferably an aromatic carbon ring having 6 to 20 carbon atoms. A hydrogen ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms. Most preferred is a benzene ring.

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

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

Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, i-propyl, and t-butyl. , N-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably carbon atoms). 2 to 8, for example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably having 2 to 12 carbon atoms, particularly preferably carbon). 2 to 8, for example, propargyl, 3-pentynyl, etc.), an aryl group (preferably having 6 to 30 carbon atoms, more preferably Or having 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, etc.), a substituted or unsubstituted amino group (preferably having 0 to 20 carbon atoms). More preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc.), an alkoxy group (preferably having 1 carbon atom). To 20, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more preferably). Has 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy and 2-naphthyloxy. ), An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, pivaloyl, etc.), alkoxycarbonyl A group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), an aryloxycarbonyl group (preferably 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl, etc.), acyloxy group (preferably 2 to 20 carbon atoms, more preferably Has 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetoxy, benzoyl Examples include oxy. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino), alkoxycarbonylamino group (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino group (preferably having carbon number) 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino, and the like, and sulfonylamino groups (preferably 1 to 20 carbon atoms, more preferably Has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. And sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl and methylsulfamoyl). , Dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as carbamoyl). , Methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, Ethylthio etc.), arylthio group (preferably Has 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably Has 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms). For example, ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms) More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, diethyl phosphoric acid amide, phenylphosphoric acid amide etc. are mentioned. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, piperidyl , Morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms). For example, trimethylsilyl, triphenylsilyl, etc.) . These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

As the general formula (3), a compound represented by the following general formula (3-1) is preferable.
General formula (3-1):

In the general formula (3-1), R ³¹ , R ³² , R ³³ , R ³⁴ , R ³⁵ , R ³⁶ , R ³⁷ and R ³⁸ each independently represent a hydrogen atom or a substituent. The substituent T can be applied. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ³¹ and R ³³ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and a C1-12 alkyl group, particularly preferably a C1-12 alkyl group (preferably Is carbon number 4-12).

R ³² and R ³⁴ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, and more preferably Is a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group or a halogen atom, more preferably a hydrogen atom or a carbon 1-12 alkyl group, particularly preferably a hydrogen atom or a methyl group, Preferably it is a hydrogen atom.

R ³⁵ and R ³⁸ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and a C1-12 alkyl group, particularly preferably a hydrogen atom and a methyl group, most preferably Is a hydrogen atom.

R ³⁶ and R ³⁷ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and a halogen atom, and particularly preferably a hydrogen atom and a chlorine atom.

As the general formula (3), a compound represented by the following general formula (3-2) is more preferable.
Formula (3-2):

In the formula, R ³¹ , R ³³ , R ³⁶ and R ³⁷ have the same meanings as those in the general formula (3-1), and preferred ranges thereof are also the same.

  Although the specific example of a compound represented by General formula (3) below is given, this invention is not limited to the following specific example at all.

  Among the benzotriazole compounds listed above, those having a molecular weight of 320 or more were confirmed to be advantageous in terms of retention when the cellulose acylate film of the present invention was produced.

In addition, as the benzophenone compound which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (4) are preferably used.
General formula (4):

In the formula, Q ⁴¹ and Q ⁴² each independently represents an aromatic ring. X ⁴¹ represents NR ⁴¹ (R ⁴¹ represents a hydrogen atom or a substituent), an oxygen atom or a sulfur atom.

The aromatic ring represented by Q ⁴¹ and Q ⁴² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

The aromatic hydrocarbon ring represented by Q ⁴¹ and Q ⁴² is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring or a naphthalene ring), more preferably An aromatic hydrocarbon ring having 6 to 20 carbon atoms, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms. More preferred is a benzene ring.

The aromatic hetero ring represented by Q ⁴¹ and Q ^42, which is preferably an oxygen atom, a nitrogen atom or at least one containing aromatic heterocycle any one sulfur atom. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, Examples include quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzothiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.

The aromatic ring represented by Q ⁴¹ and Q ⁴² is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, still more preferably a substituted or unsubstituted benzene ring. is there.

Q ⁴¹ and Q ⁴² may further have a substituent, and the above-described substituent T is preferable, but the substituent does not include a carboxylic acid, a sulfonic acid, or a quaternary ammonium salt. Further, if possible, substituents may be linked to form a ring structure.

X ⁴¹ represents NR ⁴² (R ⁴² represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied), an oxygen atom or a sulfur atom, and X ⁴¹ is preferably NR ⁴² ( R ⁴² is preferably an acyl group or a sulfonyl group, and these substituents may be further substituted.) Or oxygen, and particularly preferably oxygen.

As the general formula (4), a compound represented by the following general formula (4-1) is preferable.
Formula (4-1):

In the formula, R ⁴¹¹ , R ⁴¹² , R ⁴¹³ , R ⁴¹⁴ , R ⁴¹⁵ , R ⁴¹⁶ , R ⁴¹⁷ , R ⁴¹⁸ and R ⁴¹⁹ each independently represent a hydrogen atom or a substituent, The group T can be applied. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ⁴¹¹ , R ⁴¹³ , R ⁴¹⁴ , R ⁴¹⁵ , R ⁴¹⁶ , R ⁴¹⁸ and R ⁴¹⁹ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, An aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, still more preferably a hydrogen atom and a carbon 1-12 alkyl group. And particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ⁴¹² is preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, aryloxy group, hydroxy group, halogen atom, more preferably a hydrogen atom or carbon number. An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably an alkoxy group having 1 to 20 carbon atoms. And particularly preferably an alkoxy group having 1 to 12 carbon atoms.

R ⁴¹⁷ is preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, aryloxy group, hydroxy group, halogen atom, more preferably a hydrogen atom or carbon number. An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and 1 to 20 carbon atoms. Alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and still more preferably a methyl group), particularly preferably a methyl group or a hydrogen atom.

As the general formula (4), a compound represented by the following general formula (4-2) is more preferable.
Formula (4-2):

In the formula, R ⁴²⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. The group T can be applied. R ⁴²⁰ is preferably a substituted or unsubstituted alkyl group, more preferably a substituted or unsubstituted alkyl group having 5 to 20 carbon atoms, and still more preferably a substituted or unsubstituted alkyl group having 5 to 12 carbon atoms. Group (including n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substituent having 6 to 12 carbon atoms. Or an unsubstituted alkyl group (2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group).

  The compound represented by the general formula (4) can be synthesized by a known method described in JP-A-11-12219.

  Although the specific example of a compound represented by General formula (4) below is given, this invention is not limited to the following specific example at all.

As the compound containing a cyano group, which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (5) are preferably used.
General formula (5):

In the formula, Q ⁵¹ and Q ⁵² each independently represent an aromatic ring. X ⁵¹ and X ⁵² each represents a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle. The aromatic ring represented by Q ⁵¹ and Q ⁵² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

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

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

The aromatic ring represented by Q ⁵¹ and Q ⁵² is preferably an aromatic hydrocarbon ring, and more preferably a benzene ring. Q ⁵¹ and Q ⁵² may further have a substituent, and the above-described substituent T is preferable.

X ⁵¹ and X ^{52 each} represents a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle. The substituent T described above can be applied to the substituents represented by X ⁵¹ and X ⁵² . In addition, the substituent represented by X ⁵¹ and X ⁵² may be further substituted with another substituent, and X ⁵¹ and X ⁵² may be condensed to form a ring structure.

X ⁵¹ and X ⁵² are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocyclic ring, more preferably a cyano group, a carbonyl group, a sulfonyl group, An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group {—C (═O) OR ⁵¹ (R ⁵¹ is a C 1-20 alkyl group, carbon 6 to 12 aryl groups and combinations thereof)}.

As the general formula (5), a compound represented by the following general formula (5-1) is preferable.
General formula (5-1):

In the formula, each of R ⁵¹¹ , R ⁵¹² , R ⁵¹³ , R ⁵¹⁴ , R ⁵¹⁵ , R ⁵¹⁶ , R ⁵¹⁷ , R ⁵¹⁸ , R ⁵¹⁹ and R ⁵²⁰ independently represents a hydrogen atom or a substituent. The above substituent T can be applied. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ⁵¹¹ , R ⁵¹² , R ⁵¹⁴ , R ⁵¹⁵ , R ⁵¹⁶ , R ⁵¹⁷ , R ⁵¹⁹ and R ⁵²⁰ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, An alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, still more preferably a hydrogen atom and carbon 1-12. An alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ⁵¹³ and R ⁵¹⁸ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, halogen atoms, more preferably hydrogen atoms. , An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and a carbon number. It is a C1-C12 alkyl group and a C1-C12 alkoxy group, Especially preferably, it is a hydrogen atom.

X ⁵¹¹ and X ⁵¹² are respectively synonymous with X ⁵¹ and X ⁵² in the general formula (5).

As the general formula (5), a compound represented by the following general formula (5-2) is more preferable.
General formula (5-2):

In the formula, R ⁵¹³ and R ⁵¹⁸ have the same meanings as those in formula (5-1), and preferred ranges are also the same.

X ⁵¹³ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with another substituent. X ⁵¹³ is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group or an aromatic heterocycle, more preferably a cyano group, a carbonyl group, a sulfonyl group or an aromatic heterocycle. A ring, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group {—C (═O) OR ⁵² (R ⁵² is an alkyl group having 1 to 20 carbon atoms, 6 to 6 carbon atoms). 12 aryl groups and combinations thereof)}.

As the general formula (5), a compound represented by the general formula (5-3) is more preferable.
General formula (5-3):

In the formula, R ⁵¹³ and R ⁵¹⁸ have the same ^{meanings as} those in formula (5-1), and preferred ranges are also the same. R ⁵² represents an alkyl group having 1 to 20 carbon atoms. R ⁵² is preferably an alkyl group having 2 to 12 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms, and still more preferably carbon when R ⁵¹³ and R ⁵¹⁸ are both hydrogen. An alkyl group of 6 to 12, particularly preferably an n-octyl group, a t-octyl group, a 2-ethylhexyl group, an n-decyl group, and an n-dodecyl group, and most preferably to 2-ethyl. Xyl group.

As R ⁵² , preferably, when R ⁵¹³ and R ⁵¹⁸ are other than hydrogen, the compound represented by the general formula (5-3) has a molecular weight of 300 or more and an alkyl group having 20 or less carbon atoms. Is preferred.

  In the present invention, the compound represented by the general formula (5) can be synthesized by the method described in “J. Am. Chem. Soc.”, 63, 3452 (1941).

  Although the specific example of a compound represented by General formula (5) below is given, this invention is not limited to the following specific example at all.

(Matting agent fine particles)
It is preferable to add fine particles as a matting agent to the cellulose acylate film in the invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and Mention may be made of calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / L 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 / L or more, and more preferably 100 to 200 g / L or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and are present in the film as aggregates of primary particles, and 0.1 to 3 on the film surface. An unevenness of 0.0 μm is formed. The secondary average particle size is preferably from 0.2 μm to 1.5 μm, more preferably from 0.4 μm to 1.2 μm, and most preferably from 0.6 μm to 1.1 μm. The primary and secondary particle sizes were determined by observing the particles in the film with a scanning electron microscope and determining the diameter of a circle circumscribing the particles as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

  The fine particles of silicon dioxide include, for example, “Aerosil R972”, “Aerosil R972V”, “Aerosil R974”, “Aerosil R812”, “Aerosil 200”, “Aerosil 200V”, “Aerosil 300”, “Aerosil R202”, “Aerosil”. Commercial products such as “OX50” and “Aerosil TT600” {manufactured by Nippon Aerosil Co., Ltd.} can be used. The fine particles of zirconium oxide are commercially available under the trade names of “Aerosil R976” and “Aerosil R811” {manufactured by Nippon Aerosil Co., Ltd.}, for example.

  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 / L or more, and the turbidity of the optical film is low. This is particularly preferable because the effect of reducing the coefficient of friction is large while maintaining it.

In the present invention, in order to obtain a cellulose acylate film having particles having a small secondary average particle size, 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 stirred and mixed in advance, adding the fine particle dispersion to a small amount of a separately prepared cellulose acylate solution, stirring and dissolving, and further mixing with a main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, add a small amount of cellulose ester to the solvent, dissolve with stirring, add fine particles to this, disperse with a disperser to make this fine particle additive solution, and mix this fine particle additive solution with the dope solution using an in-line mixer There is also a way to do it. Although this invention is not limited to these methods, 5-30 mass% is preferable, and, as for the density | concentration of silicon dioxide when mixing silicon dioxide microparticles | fine-particles with a solvent etc., 10-25 mass% is still more preferable, 15-15. Most preferred is 20% by weight. 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 a lower alcohol 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 formation of a cellulose ester.

(Plasticizer, degradation inhibitor, release agent)
In the cellulose acylate film used in the present invention, in addition to the compound for reducing optical anisotropy and the wavelength dispersion adjusting agent described above, various additives (for example, plasticizers) according to applications in each preparation step. , UV inhibitors, deterioration inhibitors, release agents, infrared absorbers, etc.), which may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorber at 20 ° C. or lower and 20 ° C. or higher, and similarly, mixing of a plasticizer is described in, for example, Japanese Patent Application Laid-Open No. 2001-151901. Moreover, as an infrared absorber, what was described, for example in Unexamined-Japanese-Patent No. 2001-194522 can be used. Furthermore, the addition time may be added at any time in the dope preparation step, but may be added to the final preparation step of the dope preparation step by adding a step of adding an additive. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Furthermore, when the cellulose acylate film is formed from multiple layers, the type and amount of additives in each layer may be different, and are described in, for example, Japanese Patent Application Laid-Open No. 2001-151902. This is a known technique. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.

(Ratio of each compound addition)
In the cellulose acylate film used in the present invention, the total amount of compounds having a molecular weight of 3000 or less is preferably 5 to 45% by mass with respect to the mass of cellulose acylate. More preferably, it is 10-40 mass%, More desirably, it is 15-30 mass%. These compounds include, as described above, compounds that reduce optical anisotropy, wavelength dispersion modifiers, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, and the like, and molecular weight Is preferably 3000 or less, more preferably 2000 or less, and even more preferably 1000 or less. If the total amount of these compounds is equal to or greater than the lower limit value, the properties of the cellulose acylate alone will not be excessive. For example, the optical performance and physical strength are likely to fluctuate due to changes in temperature and humidity. Does not occur. Also, if the total amount of these compounds is less than or equal to the upper limit, problems such as exceeding the limit of compatibility of the compounds in the cellulose acylate film and depositing on the film surface to cause the film to become cloudy (crying out of the film) Therefore, these compounds are preferably used within the above range as a total amount.

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

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

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

[Manufacturing process of cellulose acylate film]
[Dissolution process]
In preparing the cellulose acylate solution (dope solution) in the present invention, the dissolution method is not particularly limited, and it may be room temperature dissolution, or may be a cooling dissolution method or a high temperature dissolution method, or may be carried out in combination. Good. Regarding the preparation of the cellulose acylate solution in the present invention, and further the steps of solution concentration and filtration accompanying the dissolution step, the technical report of the Japan Society of Invention (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention) The manufacturing process described in detail on pages 22 to 25 is preferably used.

(Transparency of dope solution)
The transparency of a dope solution (hereinafter sometimes simply referred to as a dope), which is a cellulose acylate solution in the present invention, is desirably 85% or more. More preferably, it is 88% or more, and further preferably 90% or more. In the present invention, it is confirmed that various additives are sufficiently dissolved in the cellulose acylate dope solution. As a specific method for calculating the transparency of the dope, the dope solution was poured into a 1 cm square glass cell, and the absorbance at 550 nm was measured using a spectrophotometer “UV-3150” (manufactured by Shimadzu Corporation). Only the solvent was measured in advance as a blank, and the transparency of the dope was calculated from the ratio between the absorbance of the blank and the absorbance of the dope.

[Casting, drying, winding process]
Next, a method for producing a film using a cellulose acylate solution (dope) will be described. In the present invention, as a method and equipment for producing a cellulose acylate film, 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 in the dissolving machine (kettle) is temporarily stored in the storage kettle, and the foam contained in the dope is defoamed to make the final adjustment. The dope is sent from the dope discharge port to the pressurizing die through a pressurizing quantitative gear pump capable of feeding the dope with high accuracy by the number of revolutions, and then the dope is run endlessly from the die (slit) of the pressurizing die. The dope film (also referred to as a web) is peeled off from the metal support at the peeling point where the metal support is almost cast around the metal support. The obtained web is sandwiched between clips and conveyed by a tenter while holding the width to be dried, and then the obtained film is mechanically conveyed by a roll group of a drying device to finish drying, and a winder And roll up to a predetermined length in a roll. The combination of the tenter and the roll group dryer varies depending on the purpose. As the main use of the cellulose acylate film in the present invention, in the functional protective film which is an optical member for electronic displays, and in the solution casting film forming method used for the silver halide photographic light-sensitive material, the solution casting film forming In addition to the apparatus, a coating apparatus is often added for surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, and a protective layer. These are described in detail on pages 25-30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society for Invention). Including), metal support, drying, peeling and the like, and can be preferably used in the present invention.

[Physical property evaluation of cellulose acylate film]
(Change in optical performance of film after high humidity treatment)
Regarding the change of the optical performance of the cellulose acylate film in the present invention due to the environmental change, it is desirable that the amount of change in Re and Rth of the film treated at 60 ° C. and 90% RH for 240 hours is 15 nm or less. More desirably, it is 12 nm or less, and further desirably 10 nm or less.

(Change in optical performance of film after high temperature treatment)
Further, it is desirable that the amount of change in Re and Rth of the film treated at 80 ° C. for 240 hours is 15 nm or less. More desirably, it is 12 nm or less, and further desirably 10 nm or less.

(Compound volatilization after film heat treatment)
The compound that lowers Rth and the compound that lowers ΔRth, which can be desirably used in the cellulose acylate film in the present invention, have a volatilization amount of those compounds from a film treated at 80 ° C. for 240 hours, both at 30% or less. It is desirable to be. More desirably, it is 25% or less, and further desirably 20% or less.

The amount of volatilization of these compounds from the film was determined by dissolving the film treated at 80 ° C. for 240 hours and the untreated film in a solvent, detecting the compound by liquid high-speed chromatography, and determining the peak area of the compound in the film. The amount of the remaining compound was calculated by the following formula (8).
Formula (8): Volatilization amount (% by mass) = {(Amount of remaining compound in untreated product) − (Amount of remaining compound in treated product)} / (Amount of remaining compound in untreated product) × 100

(Glass glass transition temperature Tg)
The glass transition temperature Tg of the cellulose acylate film in the present invention is usually 80 to 165 ° C. From the viewpoint of heat resistance, Tg is more preferably 100 to 160 ° C, and particularly preferably 110 to 150 ° C.
The measurement of the glass transition temperature Tg was carried out using a differential scanning calorimeter “DSC2910” (manufactured by T.A. Instruments Co., Ltd.) with a cellulose acylate film sample of 10 mg of the present invention at a temperature rising / falling rate of 5 ° C./min. Then, calorimetry was performed to calculate the glass transition temperature Tg.

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

(Humidity dependence of film Re and Rth)
In the cellulose acylate film of the invention, both the retardation Re in the front direction and the retardation Rth in the film thickness direction are preferably small in change due to humidity. Specifically, the difference ΔRth _hum (= Rth _{10% RH} −Rth _{80% RH} ) between the Rth value at 25 ° C. and 10% RH and the Rth value at 25 ° C. and 80% RH is preferably 0 to 50 nm. . More preferably, it is 0-40 nm, More preferably, it is 0-35 nm.

(Equilibrium moisture content of film)
The equilibrium moisture content of the cellulose acylate film in the present invention is 25, regardless of the film thickness, so as not to impair the adhesiveness with a water-soluble polymer such as polyvinyl alcohol when used as a protective film of a polarizing plate. The equilibrium water content at 0 ° C. and 80% RH is preferably 0 to 4%. It is more preferably 0.1 to 3.5%, and particularly preferably 1 to 3%. If the equilibrium moisture content is less than or equal to the upper limit, it is preferable that the dependency of retardation due to a change in humidity does not become too great when an optically anisotropic layer is laminated to form an optical compensation sheet.
The water content is measured by a Karl Fischer method using a cellulose acylate film sample 7 mm × 35 mm, using a moisture measuring device and a sample drying apparatus “CA-03”, “VA-05” (both manufactured by Mitsubishi Chemical Corporation). Measured with The moisture content (g) was calculated by dividing by the sample mass (g).

(Water permeability of film)
The moisture permeability of the cellulose acylate film used in the optical compensation sheet of the present invention is determined based on JIS Z-0208 under the conditions of a temperature of 60 ° C. and a humidity of 95% RH, and converted to a film thickness of 80 μm. The moisture permeability of the film is preferably 400 to 2000 g / m ² · 24 h. More preferably 500~1800g / m ² · 24h, and particularly preferably 600~1600g / m ² · 24h. If the moisture permeability of the film is equal to or lower than the upper limit value, the absolute value of the humidity dependency of the Re value and Rth value of the film does not tend to exceed 0.5 nm /% RH, which is preferable. In addition, when an optically anisotropic sheet is formed by laminating an optically anisotropic layer on a cellulose acylate film, the absolute value of the humidity dependence of the Re value and Rth value tends to exceed 0.5 nm /% RH. This is preferable because there is nothing. When such an optical compensation sheet or a polarizing plate combined with the optical compensation sheet is incorporated in a liquid crystal display device, it is preferable because problems such as a change in color and a change in viewing angle do not occur. Also, if the moisture permeability of the cellulose acylate film is equal to or higher than the lower limit, the adhesive is dried by the cellulose acylate film when such a film is attached to both surfaces of the polarizing film to produce a polarizing plate. This is preferable because it is not hindered and does not cause problems such as poor adhesion.

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 a sample having any film thickness by setting the reference to 80 μm. The film thickness was converted according to the following mathematical formula (9).
The following mathematical formula (9): moisture permeability in terms of 80 μm = measured moisture permeability × measured film thickness (μm) / 80 μm

The method for measuring moisture permeability is “Polymer Physical Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: “Measurement of vapor permeation” (mass method, thermometer method, vapor pressure method, adsorption amount) The method described in (Method) can be applied. The measurement is performed by conditioning a cellulose acylate film sample 70 mmφ at 25 ° C., 90% RH, 60 ° C., and 95% RH for 24 hours, respectively, and using a moisture permeation test apparatus “KK-709007” {manufactured by Toyo Seiki Co., Ltd.}. Then, according to JIS Z-0208, the amount of water per unit area was calculated (g / m ² ), and the moisture permeability was determined as follows: moisture content after humidity conditioning−mass before moisture conditioning.

(Dimensional change of film)
The dimensional stability of the cellulose acylate film used in the present invention is such that the dimensional change rate after standing for 24 hours at 60 ° C. and 90% RH (high humidity), and 90 ° C. and 5% RH. It is desirable that the rate of dimensional change when standing for 24 hours under conditions (high temperature) is 0.5% or less. More desirably, it is 0.3% or less, and further desirably is 0.15% or less.

As a specific measurement method, two cellulose acylate film samples 30 mm × 120 mm were prepared, conditioned at 25 ° C. and 60% RH for 24 hours, and both ends with an automatic pin gauge {manufactured by Shinto Kagaku Co., Ltd.}. 6 mmφ holes were formed at intervals of 100 mm, and the original size (L ₀ ) of the interval between the holes was defined. After one sample was treated at 60 ° C. and 90% RH for 24 hours, the hole spacing dimension (L ₁ ) was measured, and another sample was treated at 90 ° C. and 5% RH for 24 hours. The hole spacing dimension (L ₂ ) was measured. Measurement was made to a minimum scale of 1/1000 mm at all intervals. Based on the obtained results, the dimensional change rate was determined by the following mathematical formulas (10) and (11).
Formula (10): Dimensional change rate (%) of 60 ° C. and 90% RH (high humidity) = {| L ₀ −L ₁ | / L ₀ } × 100
Formula (11): Dimensional change rate (%) of 90 ° C., 5% RH (high temperature) = {| L ₀ −L ₂ | / L ₀ } × 100

(Mechanical modulus of film)
Elastic modulus of the cellulose acylate film for use in the present invention is preferably 200 to 500 kgf / mm ^2, more preferably 240~470kgf / mm ^2, more preferably from 270~440kgf / mm ^2. A specific measurement method is to measure the stress at 0.5% elongation at a tensile rate of 10% / min in an atmosphere of 23% and 70% RH using a universal tensile tester “STM T50BP” manufactured by Toyo Baldwin Co., Ltd. The mechanical elastic modulus was obtained.

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

(Detection of change in film Re and slow axis before and after stretching)
A cellulose acylate film 100 × 100 mm as a sample was prepared, and stretched in the machine transport direction (MD direction) or the width direction (TD direction) under a temperature of 140 ° C. using a fixed uniaxial stretching machine. The front retardation Re of each sample before and after stretching was measured using an automatic birefringence meter “KOBRA 21ADH”. The detection of the slow axis was determined from the orientation angle obtained during the retardation measurement. It is preferable that the change in Re by stretching is small, specifically, in-plane front retardation (nm) of a film in which Re _(n) is stretched by n (%), in-plane of a film in which Re ₍₀₎ is not stretched When the front retardation (nm) is used, it is preferable to satisfy the following formula (12), and it is more preferable to satisfy the formula (12-1).
Formula (12): | Re _(n) −Re ₍₀₎ | /n≦1.0
Formula (12-1): | Re _(n) −Re ₍₀₎ | /n≦0.3

[Direction with slow axis]
When the cellulose acylate film of the present invention is used as a protective film for a polarizing film, since the polarizing film has an absorption axis in the machine transport direction (MD direction), the cellulose acylate film has a slow axis in the vicinity of the MD direction or TD. It is desirable to be in the vicinity. By making the slow axis parallel or orthogonal to the polarizing film, light leakage and color change can be reduced. Here, the vicinity means that the slow axis and the MD or TD direction are in the range of 0 to 10 °, preferably 0 to 5 °.

[Cellulose acylate film with positive intrinsic birefringence]
When the cellulose acylate film in the present invention is stretched in a direction having a slow axis in the film plane, the front retardation Re increases, and when stretched in a direction perpendicular to the direction having the slow axis, the front retardation Re Becomes smaller. This indicates that the intrinsic birefringence is positive, and it is effective to stretch in the direction perpendicular to the slow axis in order to cancel Re developed in the film. As this method, for example, when the film has a slow axis in the machine conveyance direction (MD direction), tenter stretching is performed in a direction perpendicular to MD (TD direction) to reduce the front Re. It is possible. As an opposite example, in the case where the TD direction has a slow axis, it is conceivable that the front Re is reduced by increasing the tension of the machine transport roll in the MD direction and stretching.

[Cellulose acylate film with negative intrinsic birefringence]
When the cellulose acylate film in the present invention is stretched in a direction having a slow axis, the front retardation Re is reduced, and when stretched in a direction perpendicular to the direction having a slow axis, the front retardation Re may be increased. is there. This indicates that the intrinsic birefringence is negative, and it is effective to stretch in the same direction as the slow axis in order to cancel out the Re developed in the film. As this method, for example, when the film has a slow axis in the machine conveyance direction (MD direction), the front Re is reduced by stretching the machine conveyance roll in the MD direction while increasing the tension. Can be considered. As an opposite example, when the TD direction has a slow axis, it is conceivable to perform tenter stretching in a direction perpendicular to the MD (TD direction) to reduce the front Re.

[Method for evaluating cellulose acylate film]
In evaluating the cellulose acylate film used in the present invention, measurement was carried out by the following method.

(In-plane retardation Re, thickness direction retardation Rth)
A cellulose acylate film sample 30 mm × 40 mm was conditioned at 25 ° C. and 60% RH for 2 hours, and Re _λ was measured using an automatic birefringence meter “KOBRA 21ADH” (manufactured by Oji Scientific Instruments), This was performed by making light having a wavelength of λ nm incident in the normal direction of the film. Rth _λ is Re _λ and the in-plane slow axis is the tilt axis, the normal direction of the film is 0 °, the film sample is tilted to 50 ° every 10 °, and light of wavelength λ nm is incident. Based on the measured retardation value, an assumed average refractive index of 1.48 and a film thickness were input and calculated.

(Measurement of chromatic dispersion of Re and Rth)
A cellulose acylate film sample 30 mm × 40 mm was conditioned at 25 ° C. and 60% RH for 2 hours, and an ellipsometer “M-150” (manufactured by JASCO Corporation) used light with a wavelength of 780 nm to 380 nm as a film normal. By making it enter in the direction, Re at each wavelength was obtained, and the wavelength dispersion of Re was measured. Further, the wavelength dispersion of Rth was measured by making light having a wavelength of 780 to 380 nm incident from a direction inclined + 40 ° with respect to the normal direction of the film with the Re and in-plane slow axis as the tilt axis. Based on the retardation value measured in three directions in total, the retardation value measured by making light with a wavelength of 780 to 380 nm incident from the direction inclined by −40 ° with respect to the normal direction of the film Calculation was performed by inputting the assumed refractive index of 1.48 and the film thickness.

(Molecular orientation axis)
Cellulose acylate film sample 70 mm x 100 mm was conditioned for 2 hours at 25 ° C and 65% RH, and with an automatic birefringence meter "KOBRA 21DH" (manufactured by Oji Scientific), the incident angle at normal incidence was changed. The molecular orientation axis was calculated from the phase difference.

(Axis misalignment)
Moreover, the axial shift angle of the cellulose acylate film was measured using an automatic birefringence meter “KOBRA 21ADH” (manufactured by Oji Scientific Instruments). Twenty points were measured at equal intervals over the entire width in the width direction, and the average absolute value was determined. Also, the slow axis angle (axis deviation) range is measured at 20 points at equal intervals over the entire width direction, and the difference between the average of 4 points from the larger absolute value of the axis deviation and the average of 4 points from the smaller one. It is what I took.

(Transmittance)
A transmittance of visible light (615 nm) was measured on a cellulose acylate film sample 20 mm × 70 mm at 25 ° C. and 60% RH using a transparency measuring instrument “AKA Phototube Colorimeter” (manufactured by KOTAKI MFG. Co., Ltd.). .

(Spectral characteristics)
Using a spectrophotometer “U-3210” {manufactured by Hitachi, Ltd.}, a transmittance of a cellulose acylate film sample 13 mm × 40 mm was measured at 25 ° C. and 60% RH at a wavelength of 300 to 450 nm. The slope width was determined by (72% wavelength−5% wavelength). The limit wavelength was expressed by a wavelength of (gradient width / 2) + 5%. The absorption edge is represented by a wavelength having a transmittance of 0.4%. From this, the transmittance | permeability of 380 nm and 350 nm was evaluated.

(Film surface properties)
The surface of the cellulose acylate film in the invention is based on JIS B-0601-1994, the arithmetic average roughness (Ra) of the surface irregularities of the film is 0.1 μm or less, and the maximum height (Ry) is 0.5 μm. The following is preferable. Preferably, the arithmetic average roughness (Ra) is 0.05 μm or less, and the maximum height (Ry) is 0.2 μm or less. The concave and convex shapes on the film surface can be evaluated by an atomic force microscope (AFM).

(In-plane variation of retardation of cellulose acylate film)
The cellulose acylate film in the invention desirably satisfies the following formula (15).
Formula (13): | Re _max −Re _min | ≦ 3 and | Rth _max −Rth _min | ≦ 5
(In the formula, Re _max and Rth _max are the maximum retardation values of 1 m square film cut out arbitrarily, and Re _min and Rth _min are the minimum values thereof.]

(Retention of film)
In the cellulose acylate film used in the present invention, retention of various compounds added to the film is required. Specifically, when the cellulose acylate film is allowed to stand for 48 hours under the conditions of 80 ° C. and 90% RH, the mass change of the film is preferably 0 to 5%. More preferably, it is 0 to 3%, and still more preferably 0 to 2%.

(Method for evaluating holdability)
A cellulose acylate film sample was cut into a size of 10 cm × 10 cm, and the mass after being left for 24 hours in an atmosphere of 23 ° C. and 55% RH was measured. Under the conditions of 80 ± 5 ° C. and 90 ± 10% RH Left for 48 hours. The surface of the sample after the treatment was lightly wiped, the mass after being left for 1 day at 23 ° C. and 55% RH was measured, and the retention property was calculated according to the following formula (14).
Formula (14): Retention property (mass%) = {(mass before being left−mass after being left) / mass before being left} × 100

(Mechanical properties of film)
(curl)
The curl value in the width direction of the cellulose acylate film in the invention is preferably from −10 / m to + 10 / m. In the cellulose acylate film of the present invention, the surface treatment described later, the rubbing treatment when applying the optically anisotropic layer, the alignment film, the coating and bonding of the optically anisotropic layer, etc. are long. When performing, if the curl value in the width direction of the cellulose acylate film is within this range, problems such as film handling being hindered and film cutting are unlikely to occur. Also, at the edge or center of the film, the film will come into strong contact with the transport rolls and become more likely to generate dust, or more foreign matter will adhere to the film. Is preferable because it does not cause problems such as exceeding the allowable value. Further, by setting the curl within this range, it is possible to reduce color spot failure that is likely to occur when the optically anisotropic layer is installed, and it is possible to prevent bubbles from entering when the polarizing film is bonded, which is preferable.
The curl value can be measured according to a measurement method (ANSI / ASCPH1.29-1985) defined by the American National Standards Institute.

(Tear strength)
The tear strength (Elmendorf tear method) based on the tear test method of JIS K7128-2-1998 is preferably 2 g or more when the film thickness of the cellulose acylate film is in the range of 20 to 80 μm. More preferably, it is 5-25g, Furthermore, it is 6-25g. Moreover, 8 g or more is preferable in the film thickness conversion of 60 micrometers of a film, More preferably, it is 8-15g. Specifically, the cellulose acylate film sample piece 50 mm × 64 mm can be measured for 2 hours under conditions of 25 ° C. and 65% RH, and then measured using a light load tear strength tester.

(Residual solvent amount of film)
The cellulose acylate film in the invention is preferably dried under conditions such that the residual solvent amount is in the range of 0.01 to 1.5% by mass. More preferably, it is 0.01-1.0 mass%. Curling can be suppressed by setting the residual solvent amount of the transparent film used in the present invention to 1.5% or less. More preferably, it is 1.0% or less. This is presumably because a reduction in the free volume becomes the main effect factor by reducing the amount of residual solvent during film formation by the solvent casting method.

(Hygroscopic expansion coefficient of film)
The hygroscopic expansion coefficient of the cellulose acylate film in the present invention is preferably 30 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably 15 × 10 ⁻⁵ /% RH or less, and more preferably 10 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably small, but usually it is 1.0 × 10 ⁻⁵ /% RH or more. The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature. By adjusting the hygroscopic expansion coefficient, when an optically anisotropic sheet is laminated on the cellulose acylate film to obtain an optical compensation sheet, the optical transmittance is maintained while maintaining the optical compensation function. Light leakage can be prevented.

(Film surface treatment)
Cellulose acylate film can be bonded to cellulose acylate film and optically anisotropic layer and functional layers (for example, undercoat layer and back layer) according to necessity by performing surface treatment. Improvement can be achieved. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used.
The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A gas that is plasma-excited under such conditions is called a plasma-excitable gas, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, and tetrafluoromethane, and mixtures thereof. Details of these are described in detail in pages 30 to 32 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention), and are preferably used in the present invention. be able to.

(Contact angle of film surface by alkali saponification treatment)
In the present invention, when a cellulose acylate film is used as a protective film for a polarizing plate, an alkali saponification treatment can be mentioned as one of effective means for the surface treatment of the film. In this case, the contact angle on the film surface after the alkali saponification treatment is desirably 55 ° or less. More desirably, it is 50 ° or less, and further desirably 45 ° or less. The contact angle evaluation method can be used as an evaluation of hydrophilicity / hydrophobicity by a usual method of dropping a water droplet having a diameter of 3 mm on the surface of the film after the alkali saponification treatment and obtaining an angle formed by the film surface and the water droplet.

(Light resistance)
As an index of light durability of cellulose acylate in the present invention, it is desirable that the color difference ΔE ^{* ab} of the film when irradiated with super xenon light for 240 hours is 20 or less.
More desirably, it is 18 or less, and further desirably 15 or less. For the measurement of the color difference, “UV3100” {manufactured by Shimadzu Corporation} was used. The method of measurement is that the film is conditioned at 25 ° C. and 60% RH for 2 hours or more, then color measurement of the film before xenon light irradiation is performed, and the initial values (L ₀ ^* , a ₀ ^* , b ₀ ^* ) are set. Asked. Thereafter, the film alone was irradiated with xenon light for 240 hours under conditions of 150 W / m ² , 60 ° C. and 50% RH with a super xenon weather meter “SX-75” (manufactured by Suga Test Instruments Co., Ltd.). After the elapse of a predetermined time, the film is taken out from the thermostatic chamber, adjusted to 25 ° C. and 60% RH for 2 hours, then subjected to color measurement again, and values after irradiation (L ₁ ^* , a ₁ ^* , b ₁ ^*). ) From these, the color difference ΔE ^{* ab} was determined according to the following formula (15).
Formula (15): ΔE ^{* ab} = [(L ₀ ^* −L ₁ ^* ) ² + (a ₀ ^* −a ₁ ^* ) ² + (b ₀ ^* −b ₁ ^* ) ² ] ^0.5

(Optically anisotropic layer)
Next, details of preferred embodiments of the optically anisotropic layer made of a liquid crystalline compound will be described.
The optically anisotropic layer is preferably designed so as to compensate for the liquid crystalline compound in the liquid crystal cell in the black display of the liquid crystal display device. The alignment state of the liquid crystal compound in the liquid crystal cell in black display varies depending on the mode of the liquid crystal display device. Regarding the alignment state of the liquid crystal compound in this liquid crystal cell, “IDW'00, FMC7-2” p. 411-414. The optically anisotropic layer contains a liquid crystal compound in which the orientation is controlled by an orientation axis such as a rubbing axis and the orientation is fixed.

[Liquid crystal compounds]
The liquid crystalline compound used for the optically anisotropic layer includes a rod-like liquid crystalline compound and a discotic liquid crystalline compound. The rod-like liquid crystal compound and the discotic liquid crystal compound may be a high-molecular liquid crystal or a low-molecular liquid crystal, and further include those in which the low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity. When a rod-like liquid crystalline compound is used for producing the optically anisotropic layer, the rod-like liquid crystalline compound is preferably oriented with its major axis parallel to the orientation axis. Also, when a discotic liquid crystalline compound is used for the production of the optically anisotropic layer, it is preferable that the discotic liquid crystalline compound is aligned with its long axis (disk surface) parallel to the alignment axis. The hybrid orientation described later in which the angle (tilt angle) formed by the disk surface and the layer plane changes in the depth direction is more preferable.

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  The rod-like liquid crystalline compound includes a metal complex. Moreover, the liquid crystal polymer which contains a rod-shaped liquid crystalline compound in a repeating unit can also be used as a rod-shaped liquid crystalline compound. In other words, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer.

  Regarding rod-like liquid crystalline compounds, “Quarterly Chemical Review” Vol. 22, “Liquid Crystal Chemistry” (1994) Chapter 4, Chapter 7 and Chapter 11 of the Chemical Society of Japan and “Liquid Crystal Device Handbook” Japan Society for the Promotion of Science It is described in Chapter 3 of Chapter 142.

  The birefringence of the rod-like liquid crystalline compound is preferably in the range of 0.001 to 0.7.

The rod-like liquid crystalline compound preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radical polymerizable unsaturated group or a cationic polymerizable group. Specifically, for example, the polymerizable group described in paragraphs [0064] to [0086] of JP-A-2002-62427 is described. And polymerizable liquid crystal compounds.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystal compounds include C.I. Benzene derivatives described in Destrade et al., “Mol. Cryst.”, 71, 111 (1981), C.I. A research report of Destrade et al., “Mol. Cryst.”, 122, 141 (1985) and “Physics lett, A”, 78, 82 (1990); Kohne et al., “Angew. Chem.”, Vol. 96, p. 70 (1984); M.M. Lehn et al., "J. Chem. Commun.", P. 1794 (1985) and J. Chem. Examples include the azacrown and phenylacetylene macrocycles described in the research report “J. Am. Chem. Soc.”, 116, 2655 (1994) by Zhang et al.

  As a discotic liquid crystalline compound, a compound having liquid crystallinity in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline compound, the compound finally contained in the optically anisotropic layer does not have to be a discotic liquid crystalline compound. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or crosslinked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.

  In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in JP-A 2000-155216, paragraph numbers [0151] to “0168”.

  In the hybrid alignment, the angle between the major axis (disc surface) of the discotic liquid crystalline compound and the surface of the transparent film, that is, the inclination angle is in the direction of the depth of the optically anisotropic layer (that is, perpendicular to the transparent film), And it increases or decreases with increasing distance from the plane of the polarizing film. The angle preferably decreases with increasing distance. Further, the change in the inclination angle can be continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. . The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if a region where the angle does not change is included, it may be increased or decreased as a whole. However, it is preferred that the tilt angle changes continuously.

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

[Other additives in optically anisotropic layer]
In the optically anisotropic layer, in addition to the above liquid crystalline compound, a plasticizer, a fluorine compound, a polymerizable monomer, etc. are used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, etc. Can be improved. It is preferable that the compound has compatibility with the liquid crystal compound and can change the tilt angle of the liquid crystal compound or does not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the polymerizable group-containing liquid crystalline compound. Examples thereof include those described in JP-A-2002-296423, paragraph numbers [0018] to [0020]. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline compound.

  Examples of the fluorine-based compound include conventionally known compounds. Specifically, for example, compounds described in JP-A No. 2001-330725, paragraph numbers [0028] to [0056], and Japanese Patent Application No. 2004-274396 are described. And the like.

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

[Formation of optically anisotropic layer]
The optically anisotropic layer can be formed by applying a liquid crystal compound and, if necessary, a coating liquid containing a polymerizable initiator and an optional component described later on the alignment film.

  As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

  The coating liquid can be applied by a known method (for example, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method, slot die coating method).

  The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

(Fixing the alignment state of liquid crystalline compounds)
The aligned liquid crystalline compound can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substitution Aromatic acyloin compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone ( U.S. Pat. No. 3,549,367), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (described in U.S. Pat. No. 4,221,970) It is.

  The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

Light irradiation for the polymerization of the liquid crystalline compound is preferably performed using ultraviolet rays. The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

  A protective layer may be provided on the optically anisotropic layer.

[Surface treatment of cellulose acylate film]
The cellulose acylate film used in the present invention is preferably subjected to a surface treatment as necessary in order to have adhesion with a layer formed thereon. The surface treatment includes corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment and ultraviolet irradiation treatment. Details of these are described in detail on pages 30 to 32 of the aforementioned public technical number 2001-1745. Among these, alkali saponification treatment is particularly preferable, and it is extremely effective as the surface treatment of the cellulose acylate film.

  The alkali saponification treatment may be any method such as immersing the film in a saponification solution or applying a saponification solution to the film, but an application method is preferred. 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.

  Examples of the alkali saponification solution include potassium hydroxide solution and sodium hydroxide solution, and the prescribed concentration of hydroxide ions is preferably in the range of 0.1 to 3.0N. Furthermore, as an alkali treatment liquid, a solvent (for example, isopropyl alcohol, n-butanol, methanol, ethanol, etc.) having good wettability to the film, a surfactant, a wetting agent (for example, diols, glycerin, etc.) is contained. Thus, the wettability of the saponification solution to the transparent film, the aging stability of the saponification solution, and the like are improved. Specific examples include the contents described in JP 2002-82226 A and WO 02/46809 pamphlet.

  Instead of or in addition to the surface treatment, a primer layer (described in JP-A-7-333433) and a single resin layer such as gelatin containing both hydrophobic groups and hydrophilic groups are applied. A single layer method, or a hydrophilic resin such as gelatin that is well adhered to the polymer film as the first layer (hereinafter abbreviated as the first subbing first layer) and that adheres well to the alignment film as the second layer thereon. The content of what is called a multilayer method (for example, Unexamined-Japanese-Patent No. 11-248940) which apply | coats a layer (henceforth an undercoat 2nd layer) is mentioned.

[Alignment film]
The alignment film has a function of defining the alignment direction of the liquid crystalline compound. Therefore, the alignment film is indispensable for realizing a preferred embodiment of the present invention. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the transparent film.

  The alignment film is an organic compound (for example, ω-tricosanoic acid) by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

  The means for generating the alignment function is not particularly limited, but it is preferable to use a polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.

  In the present invention, in addition to the function of aligning liquid crystal molecules, a crosslinkable function having a function of binding a side chain having a crosslinkable functional group (for example, a double bond) to the main chain or aligning liquid crystal molecules. It is preferred to introduce the group into the side chain.

  In the configuration of the present invention, the polymer layer itself constituting the optically anisotropic layer can function as an alignment film. In that case, the polymer layer can be rubbed. Moreover, after surface-treating a polymer layer as needed, an alignment film layer can also be formed by coating and subjected to a rubbing treatment.

  As the polymer used in the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used.

  Examples of the polymer include, for example, methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913, Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like are included. Silane coupling agents can be used as the polymer.

  The polymer used for the alignment film is preferably a water-soluble polymer {eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol}, and more preferably gelatin, polyvinyl alcohol, and modified polyvinyl alcohol. Polyvinyl alcohol and modified polyvinyl alcohol are most preferred.

  The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecules and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Examples include substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy), and the like. Specific examples of these modified polyvinyl alcohol compounds include those described in paragraph numbers [0022] to [0145] of JP-A No. 2000-155216 and paragraph numbers [0018] to [0022] of JP-A No. 2002-62426. Can be mentioned.

  The side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or the crosslinkable functional group is introduced into the side chain having a function of aligning liquid crystal molecules, so that it differs from the alignment film polymer. A polyfunctional monomer contained in the isotropic layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

  The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] of JP-A No. 2000-155216.

  Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent. Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specifically, for example, compounds described in paragraph Nos. [0023] to [0024] of JP-A No. 2002-62426 may be mentioned. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high-temperature and high-humidity atmosphere for a long time, sufficient durability without occurrence of reticulation can be obtained.

  The alignment film can basically be formed by applying a coating liquid containing the above-mentioned polymer as an alignment film forming material and a crosslinking agent onto a transparent film, followed by drying by heating (crosslinking) and rubbing treatment. . As described above, the crosslinking reaction may be performed at an arbitrary time after coating on the transparent film.

  When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (for example, methanol) having a defoaming action and water. The ratio of water: methanol is preferably from 0: 100 to 99: 1, and more preferably from 0: 100 to 91: 9, by mass ratio. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optically anisotropic layer reduces remarkably.

The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. The rod coating method is particularly preferable. Further, the thickness of the alignment film after drying is preferably 0.1 to 10 μm. Heat drying can be performed at 20-110 degreeC. In order to form sufficient crosslinking, 60 to 100 ° C. is preferable, and 80 to 100 ° C. is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.

  The alignment film is provided on the transparent film or the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.

  For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment step of a liquid crystal display (LCD) can be applied. That is, a method of obtaining orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rayon, rubber, nylon, polyester fiber or the like can be used. In general, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are flocked on average.

  Next, the alignment film functions to align the liquid crystal molecules of the optically anisotropic layer provided on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.

<Polarizing plate>
The polarizing plate usually has a protective film on both sides of the polarizing film. Any known protective film can be used as the protective film of the polarizing plate, but a cellulose acylate film is preferably used. As the cellulose acylate film, a cellulose acylate film used as a transparent film satisfying the mathematical formulas (1) and (2) in the present invention can also be suitably used.
The optical compensation sheet of the present invention can exert its functions remarkably by being bonded to a polarizing plate or used as a protective film for protecting the polarizing film of the polarizing plate.

<Polarizing film>
The polarizing film of the present invention is preferably a coating type polarizing film represented by one manufactured by Optiva, or a polarizing film composed of a film-forming polymer and iodine or a dichroic dye.

  Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the polymer film. It is preferable that the iodine and the dichroic dye are aligned along the polymer molecule, or the dichroic dye is aligned in one direction by self-assembly like liquid crystal.

  A general-purpose polarizing film can be produced, for example, by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the polymer film.

  The general-purpose polarizing film has iodine or dichroic dye distributed about 4 μm (about 8 μm on both sides) from the polymer surface, and in order to obtain sufficient polarization performance, it is desirable to have a thickness of at least 10 μm. . The penetrability can be controlled by the solution concentration of iodine or dichroic dye, the temperature of the bath, and the immersion time.

  As described above, the lower limit of the thickness of the polymer film is preferably 10 μm. On the other hand, the upper limit of the thickness is not particularly limited, but the thinner the better, from the viewpoint of the light leakage phenomenon that occurs when the polarizing plate is used in a liquid crystal display device. Currently, it is preferably a general-purpose polarizing plate (about 30 μm) or less, preferably 25 μm or less, and more preferably 20 μm or less. When the thickness is 20 μm or less, a light leakage phenomenon is not observed in a 17-inch liquid crystal display device.

  The polymer of the polarizing film may be cross-linked. A crosslinked polymer can be achieved by using a polymer that is itself crosslinkable. A polarizing film can be formed by reacting a polymer having a functional group or a crosslinkable polymer obtained by introducing a functional group into the polymer with light, heat, or pH change between the polymers.

  Moreover, you may introduce | transduce a crosslinked structure into a polymer with a crosslinking agent. It can be formed by cross-linking between polymers by introducing a bonding group derived from a cross-linking agent between polymers using a cross-linking agent which is a compound having high reaction activity.

  Crosslinking is generally carried out by applying a coating solution containing a polymer or a mixture of a polymer and a crosslinking agent on a transparent film and then heating. Since it is only necessary to ensure durability at the stage of the final product, the cross-linking treatment may be performed at any stage until the final polarizing plate is obtained.

  As the polymer forming the polarizing film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used. Examples of polymers include polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, gelatin, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylolacrylamide), polyvinyltoluene, chlorosulfonated polyethylene, nitrocellulose, chlorinated Polyolefin (eg, polyvinyl chloride), polyester, polyimide, polyvinyl acetate, polyethylene, carboxymethyl cellulose, polypropylene, polycarbonate and copolymers thereof (eg, acrylic acid / methacrylic acid polymer, styrene / maleimide polymer, styrene / vinyl) Toluene polymer, vinyl acetate / vinyl chloride polymer, ethylene / vinyl acetate polymer). Water-soluble polymers {eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol} are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. .

  The saponification degree of polyvinyl alcohol and modified polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%, and most preferably 95 to 100%. As for the polymerization degree of polyvinyl alcohol, 100-5000 are preferable.

  Modified polyvinyl alcohol is obtained by introducing a modifying group into polyvinyl alcohol by copolymerization modification, chain transfer modification or block polymerization modification.

In the copolymerization modification, —COONa, —Si (OH) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO—, —SO ₃ Na, —C ₁₂ H ₂₅ may be introduced as modifying groups. it can. In chain transfer modification, —COONa, —SH, or —SC ₁₂ H ₂₅ can be introduced as a modifying group.

  The degree of polymerization of the modified polyvinyl alcohol is preferably 100 to 3000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509, and JP-A-9-316127.

  Unmodified polyvinyl alcohol and alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% are particularly preferable.

  Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

When a large amount of the polymer crosslinking agent is added, the heat and humidity resistance of the polarizing film can be improved, but in order to keep the orientation of iodine or the dichroic dye good, the crosslinking agent is added in an amount of 50% by mass based on the polymer. It is preferable to add less. The addition amount of the cross-linking agent is more preferably 0.1 to 20% by mass, and further preferably 0.5 to 15% by mass with respect to the polymer.

  The polymer film contains a certain amount of a crosslinking agent that has not reacted even after the crosslinking reaction has been completed. However, the amount of the remaining crosslinking agent is preferably 1.0% by mass or less and more preferably 0.5% by mass or less in the polymer. If the amount of the crosslinking agent in the binder layer is not more than the upper limit value, there is no problem in durability, which is preferable. That is, by reducing the residual amount of the crosslinking agent, the polarizing film is incorporated into a liquid crystal display device, and when used for a long time or left in a high-temperature and high-humidity atmosphere for a long time, problems such as a decrease in the degree of polarization are prevented. be able to.

  The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (for example, boric acid and borax) can also be used as a crosslinking agent.

  As the dichroic dye, an azo dye, a stilbene dye, a pyrazolone dye, a triphenylmethane dye, a quinoline dye, an oxazine dye, a thiazine dye or an anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (for example, sulfo, amino, hydroxyl).

  Examples of dichroic dyes include C.I. I. Direct Yellow 12, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Violet 48, C.I. I. Direct Blue 67, C.I. I. Direct Blue 90, C.I. I. Direct Green 59, C.I. I. Acid Red 37 is included. As for the dichroic dyes, those described in JP-A-1-161202, 1-172906, 1-172907, 1-183602, 1-248105, 1-265205, 7-261024 are used. There are descriptions in each publication.

  The dichroic dye is used as a free acid or an alkali metal salt, ammonium salt or amine salt. By blending two or more kinds of dichroic dyes, polarizing films having various hues can be produced. A polarizing film using a compound (pigment) that exhibits a black color when the polarization axes are orthogonal to each other, or a polarizing film or a polarizing plate in which various dichroic molecules are blended so as to exhibit a black color, both with a single plate transmittance and a polarizing coefficient It is excellent and preferable.

  In this invention, it is also possible to arrange | position a polarizing film and a transparent film through an adhesive agent. As the adhesive, a polyvinyl alcohol resin (including a modified polyvinyl alcohol with an acetoacetyl group, a sulfonic acid group, a carboxyl group, or an oxyalkylene group) or an aqueous boron compound solution can be used. Of these, polyvinyl alcohol resins are preferred. The thickness of the adhesive layer is preferably in the range of 0.01 to 10 μm after drying, and particularly preferably in the range of 0.05 to 5 μm.

(Production of polarizing film)
From the viewpoint of yield, the polarizing film is formed by stretching the polymer film at an angle of 10 to 80 ° with respect to the longitudinal direction (MD direction) of the polarizing film (stretching method) or rubbing (rubbing method). It is preferable to dye with a dichroic dye. The tilt angle is preferably stretched so as to match the angle formed between the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the liquid crystal display device (LCD) and the vertical or horizontal direction of the liquid crystal cell. .

  A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

  In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times.

  The stretching step may be performed in several steps including oblique stretching. By dividing into several times, it is possible to stretch more uniformly even at high magnification. Before the oblique stretching, a slight stretching (a degree to prevent shrinkage in the width direction) may be performed horizontally or vertically.

Stretching can be performed by performing tenter stretching in biaxial stretching in different steps. The biaxial stretching is the same as the stretching method performed in normal film formation. In biaxial stretching, since the film is stretched at different speeds on the left and right, the thickness of the polymer film before stretching needs to be different on the left and right. In casting film formation, by tapering the die, it is possible to make a difference between the left and right in the flow rate of the polymer solution.
As described above, a binder film that is obliquely stretched by 10 to 80 ° with respect to the MD direction of the polarizing film is produced.

  In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, orientation is obtained by rubbing the surface of the film in a certain direction using paper, gauze, felt, rayon, rubber, nylon, or polyester fiber. Generally, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are planted on average. It is preferable to carry out using a rubbing roll in which the roundness, cylindricity, and deflection (eccentricity) of the roll itself are all 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more.

  When rubbing a long film, it is preferable to transport the film at a speed of 1 to 100 m / min with a constant tension by a transport device. The rubbing roll is preferably rotatable in the horizontal direction with respect to the film traveling direction for setting an arbitrary rubbing angle. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °.

[Performance of polarizing plate]
In order to increase the contrast ratio of the liquid crystal display device, the transmittance of the polarizing plate is preferably higher and the degree of polarization is preferably higher. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and in the range of 40 to 50% in the light having a wavelength of 550 nm (of the polarizing plate). Most preferably, the maximum value of the single plate transmittance is 50%. The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

[Optical compensation sheet, stacking order and stacking angle of layers constituting polarizing plate]
The optical compensation sheet of the present invention is laminated between a polarizing film and a liquid crystal cell in the order of a transparent film and an optically anisotropic layer from the polarizing film side. The polarizing film and the optically anisotropic layer are laminated so that the absorption axis of the polarizing film and the slow axis of the optically anisotropic layer are substantially perpendicular to each other. When the polarizing plate is used, it is preferable that the optical compensation sheet also serves as a protective film on one side of the polarizing plate.
An alignment film, an adhesive layer, a further optically anisotropic layer, and the like can be appropriately added between the above layers as necessary.

[Hard coat film, antiglare film, antireflection film]
Any or all of a hard coat layer, an antiglare layer, and an antireflection layer can be applied to the optical compensation sheet and polarizing plate of the present invention and the liquid crystal display device described below. Preferred embodiments of such an antiglare film and antireflection film are described in detail in pages 54 to 57 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). Are listed.

<Liquid crystal display device>
[Configuration of general liquid crystal display device]
In the optical compensation sheet of the present invention, the transmission axis of the polarizing film and the slow axis of the optical compensation sheet may be arranged at any angle. The liquid crystal display device includes a liquid crystal cell in which liquid crystal is supported between two electrode substrates, two polarizing plates disposed on both sides thereof, and at least between the liquid crystal cell and the polarizing film of the polarizing plate. It has a configuration in which one optical compensation sheet is arranged.

  The liquid crystal layer of the liquid crystal cell is usually formed by sealing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on the substrate as a transparent film containing a conductive substance. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer, or an undercoat layer (undercoat layer) (used for adhesion of the transparent electrode layer). These layers are usually provided on the substrate. The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.

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

[TN type liquid crystal display]
The optical compensation sheet of the present invention may be used as an optical compensation sheet for a TN liquid crystal display device having a TN mode liquid crystal cell. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. The optical compensation sheet used in the TN type liquid crystal display device is described in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068). is there.

  The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Example 1 and Comparative Example 1
<Preparation of optical compensation sheet>
[Production of Cellulose Acylate Film (CA-1)]
[Preparation of Dope (D-1)]
{Preparation of Cellulose Acylate Stock Solution (CAL-1)}
First, the following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate stock solution (CAL-1).

(Composition of cellulose acylate stock solution (CAL-1))
Cellulose acetate (acetylation degree 2.86) 100.0 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass

[Preparation of matting agent solution]
20 parts by mass of silica particles “AEROSIL R972” (manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 16 nm and 80 parts by mass of methanol were mixed well for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution.

(Matting agent solution composition)
Dispersion of silica particles (average particle size 16 nm) 10.0 parts by weight Methylene chloride (first solvent) 76.3 parts by weight Methanol (second solvent) 3.4 parts by weight Cellulose acetate stock solution (CAL-1) 10.3 Parts by mass

[Preparation of additive solution]
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

(Additive solution composition)
Compound for reducing optical anisotropy (119) 49.7 parts by mass Wavelength dispersion adjusting agent (UV-102) 7.2 parts by mass Methylene chloride (first solvent) 58.4 parts by mass Methanol (second solvent) 8. 7 parts by mass Cellulose acetate stock solution (CAL-1) 12.7 parts by mass

[Production of Cellulose Acylate Film (CA-1)]
94.6 parts by mass of the cellulose acylate stock solution (CAL-1), 1.3 parts by mass of the matting agent solution and 4.1 parts by mass of the additive solution were mixed after filtration to prepare a dope (D-1). did. Next, the obtained dope (D-1) was cast using a band casting machine. The mass ratio of the compound for reducing optical anisotropy and the wavelength dispersion adjusting agent in the above composition to cellulose acetate was 12% by mass and 1.8% by mass, respectively. When the amount of residual solvent reached 30% by mass, the film was peeled from the band and dried at 140 ° C. for 40 minutes to produce a cellulose acylate film (CA-1). The residual cellulose content of the finished cellulose acylate film (CA-1) was 0.2% by mass, and the film thickness was 80 μm. Further, Re ₆₃₀ of the film (CA-1) was 2 nm (slow axis in the casting direction), Rth ₆₃₀ was 3 nm, | Re ₄₀₀ -Re ₇₀₀ | was 2 nm, and | Rth ₄₀₀ -Rth ₇₀₀ | was 12 nm. .
Rth _{λ0 at} a wavelength of 630 nm was 34 nm, and the value of Equation (3) was −2.6.

[Production of Cellulose Acylate Film (CA-2)]
[Preparation of inner layer dope (D-2) and outer layer dope (D-3)]
The following composition was put into a mixing tank and stirred while heating at 30 ° C. to dissolve each component to prepare an inner layer dope (D-2) and an outer layer dope (D-3).

{Composition of inner layer dope (D-2) and outer layer dope (D-3) (parts by mass)}
D-2 D-3
Cellulose acetate (acetylation degree 60.9%) 100 100
Triphenyl phosphate (plasticizer) 7.8 7.8
Biphenyl diphenyl phosphate (plasticizer) 3.9 3.9
Methylene chloride (first solvent) 293 314
Methanol (second solvent) 71 76
1-butanol (third solvent) 1.5 1.6
Silica fine particles 0 0.8
“AEROSIL R972” manufactured by Nippon Aerosil Co., Ltd. The following retardation increasing agent 1.50

{Production of cellulose acylate film (CA-2)}
The obtained inner layer dope and outer layer dope were cast on a drum cooled to 0 ° C. using a three-layer co-casting die. The film with a residual solvent amount of 70% by mass is peeled off from the drum, both ends are fixed with a pin tenter, and the film is dried at 80 ° C. while being conveyed with a draw ratio in the conveying direction of 110%. It was dried at 110 ° C. Then, it dried for 30 minutes at the temperature of 140 degreeC, and produced the cellulose acylate film (CA-2) (Outer layer: 3 micrometers, inner layer: 74 micrometers, outer layer: 3 micrometers) whose residual solvent is 0.3 mass%. The obtained cellulose acylate film (CA-2) had a width of 1340 mm and a thickness of 80 μm. Further, Re ₆₃₀ of the cellulose acylate film (CA-2) is 8 nm (slow axis in the casting direction), Rth ₆₃₀ is 80 nm, | Re ₄₀₀ -Re ₇₀₀ | is 8 nm, | Rth ₄₀₀ -Rth ₇₀₀ | is 16 nm. Met.

(Formation of optically anisotropic layer)
[Saponification treatment of cellulose acylate film]
The cellulose acylate films (CA-1) and (CA-2) are each passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature is raised to 40 ° C., and then one of the respective films. After applying 14 mL / m ^{2 of} an alkali solution having the following composition to the surface of the surface of the substrate, it was allowed to stay for 10 seconds under a steam far infrared heater {manufactured by Noritake Co., Ltd.} heated to 110 ° C. Similarly, 3 mL / m ^{2 of} pure water was applied using a bar coater. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then the film was retained in a drying zone at 70 ° C. for 2 seconds and dried.

(Alkaline solution composition)
Potassium hydroxide 4.7 parts by weight Water 15.7 parts by weight Isopropanol 64.8 parts by weight Propylene glycol 14.9 parts by weight Surfactant 1.0 part by weight C ₁₆ H ₃₃ O (CH ₂ CH ₂ O) ₁₀ H

[Formation of alignment film]
Next, the coating liquid of the following composition was apply | coated to 28 mL / m < ² > of the cellulose acylate films (CA-1) and (CA-2) with the # 16 wire bar coater, respectively. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 90 ° C. for 150 seconds. Next, the formed film was rubbed so as to be oriented in a direction parallel to the casting direction of each of the cellulose acylate films (CA-1) and (CA-2) {that is, the rubbing axis is cellulose acylate. It was parallel to the casting direction of the films (CA-1) and (CA-2)).

(Orientation film coating solution composition)
Modified polyvinyl alcohol having the following structure 20 parts by mass Water 360 parts by mass Methanol 120 parts by mass Glutaraldehyde (crosslinking agent) 1.0 part by mass

[Formation of optically anisotropic layer]
On the alignment film, the following coating solution is continuously rotated on the alignment film surface of the roll film being conveyed at 30 m / min by rotating the # 4 wire bar in the same direction as the film conveying direction at 1171 rotations. Applied. In the step of continuously heating from room temperature to 100 ° C., the solvent is dried, and then the film surface wind speed hitting the discotic liquid crystalline compound layer in the drying zone of 135 ° C. is 1.5 m / parallel to the film conveying direction. The discotic liquid crystalline compound was aligned by heating for about 90 seconds. Next, the film is transported to a drying zone at 80 ° C., and an ultraviolet ray with an illuminance of 600 mW is applied by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) with the surface temperature of the film being about 100 ° C. Irradiation was performed for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystalline compound was fixed to the orientation. Then, it was allowed to cool to room temperature and wound into a cylindrical shape to form a roll. Thus, optical compensation sheets (1) and (R1) in which an optically anisotropic layer was formed on the cellulose acylate films (CA-1) and (CA-2) were produced.

(Coating solution composition of optically anisotropic layer)
The following composition was dissolved in 107 parts by mass of methyl ethyl ketone to prepare a coating solution.
Discotic liquid crystalline compound (1) having the following structure: 41.01 parts by mass Ethylene oxide modified trimethylolpropane triacrylate “V # 360” manufactured by Osaka Organic Chemical Co., Ltd. 4.06 parts by mass Cellulose acetate butyrate 0.9 parts by mass “ CAB551-0.2 "Cellulose acetate butyrate manufactured by Eastman Chemical Co. 0.21 parts by mass" CAB531-1 "manufactured by Eastman Chemical Co., Ltd. 0.14 parts by mass of fluoro aliphatic group-containing polymer" Megafac F780 "Dainippon Ink ( Co., Ltd. Photopolymerization initiator 1.35 parts by mass “Irgacure 907” manufactured by Ciba Geigy Co., Ltd. 0.45 parts by mass “Kayacure DETX” manufactured by Nippon Kayaku Co., Ltd.

The discotic liquid crystalline compound of the optically anisotropic layer was hybrid-aligned so that the angle formed by the disk surface and the cellulose acylate film surface increased as the distance from the cellulose acylate film increased. Table 1 shows the structure of the obtained optical compensation sheet.

  When the polarizing plates are arranged in a crossed Nicol arrangement and the unevenness of the obtained optical compensation sheets (1) and (R1) is observed, no unevenness is detected even when viewed from the front and the direction inclined to 60 ° from the normal. It was.

Examples 11-1 to 11-2 and Comparative Example 11
<Preparation of polarizing plate>
(Preparation of polarizing film)
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.

[Saponification treatment of optical compensation sheet]
The optical compensation sheets (1) and (R1) obtained in Example 1 and Comparative Example 1 were immersed in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C., and then sufficiently sodium hydroxide with water. Washed away. Then, after being immersed for 1 minute in 0.005 mol / L dilute sulfuric acid aqueous solution of 35 degreeC, it was immersed in water and the dilute sulfuric acid aqueous solution was fully washed away. Finally, the sample was thoroughly dried at 120 ° C.

[Preparation of polarizing plate]
Next, the optically compensatory sheets (1) and (R1) subjected to saponification treatment are combined with a commercially available cellulose acylate film subjected to saponification treatment in the same manner to obtain a saponification treated surface of the optical compensation sheets (1) and (R1). And a saponification-treated surface of the commercially available cellulose acylate film with the polarizing film sandwiched between the polarizing films (P-1) and (RP-) with the polarizing film sandwiched therebetween. 1) was obtained. Here, “Fujitac TF80UL” {manufactured by Fuji Photo Film Co., Ltd.} was used as a commercially available cellulose acylate film. At this time, since the polarizing film, the optical compensation sheets (1) and (R1), which are protective films on both sides of the polarizing film, and “Fujitac TF80UL” are all formed in a roll form, the longitudinal direction of each roll film Are parallel and can be bonded together continuously. Therefore, the longitudinal direction of the optical compensation sheet roll (the casting direction of the cellulose acylate film) and the polarizer absorption axis are parallel to each other.

[Evaluation with TN liquid crystal cell]
A pair of polarizing plates provided in a liquid crystal display device (Syncmster 172X, manufactured by Samsung Electronics Co., Ltd.) using a TN type liquid crystal cell is peeled off, and the polarizing plates (P-1) and (RP-1) prepared above are used instead. ) Was attached to the observer side and the backlight side as shown in Table 2 through an adhesive so that the optical compensation sheet was on the liquid crystal cell side. The transmission axis of the polarizing plate on the viewer side and the transmission axis of the polarizing plate on the backlight side were arranged to be in the O mode.

(Viewing angle)
About the produced liquid crystal display device, the viewing angle was measured from black display (L1) to white display (L8) using measuring machine "EZ-Contrast160D" (made by ELDIM). A region having a contrast ratio (white transmittance / black transmittance) of 10 or more was obtained as a viewing angle in the vertical and horizontal directions. The measurement results are shown in Table 2 together with the configuration of the polarizing plate used.

(Evaluation of frame unevenness)
Under the environmental conditions of a temperature of 25 ° C. and a relative humidity of 65%, the backlight was continuously turned on for 10 to 24 hours, and the entire black display state was visually observed in a dark room to evaluate light leakage. The results are shown in Table 2.

  As can be seen from the results in Table 2 above, according to the configuration of the present invention, it is possible to provide a liquid crystal display device capable of controlling the contrast viewing angle characteristics (reducing the viewing angle) and having excellent frame unevenness.

Example 2
In Example 1, a cellulose acylate film (CA-3) was prepared by adjusting the film thickness of the cellulose acylate film (CA-1) to be 60 μm. A compensation sheet (2) was produced.

Comparative Example 2
In Comparative Example 1, the cellulose acylate film (CA-2) was adjusted to have a film thickness of 60 μm to produce a cellulose acylate film (CA-4). A compensation sheet (R2) was produced.
Table 3 shows the optical characteristics and the configuration of the obtained optical compensation sheet.

Example 12
In Example 11, instead of using the optical compensation sheet (1), a polarizing plate (P-2) was produced in the same manner as in Example 11 except that the optical compensation sheet (2) produced in Example 2 was used. When this polarizing plate was applied to a liquid crystal display device in the same manner as in Example 11 and performance evaluation was performed, it was confirmed that both the viewing angle display characteristics and the frame unevenness were good as in Example 11.

Example 3
In Example 1, an optical compensation sheet (3) was produced in the same manner as in Example 1 except that the coating liquid composition of the optically anisotropic layer was changed as follows.

Example 13
In Example 11, instead of using the optical compensation sheet (1), a polarizing plate (P-3) was produced in the same manner as in Example 11 except that this optical compensation sheet (3) was used. As in the case of Example 11, when the performance was evaluated by being attached to a liquid crystal display device, it was confirmed that the viewing angle display characteristics were also good as in Example 11.

(Coating solution composition of optically anisotropic layer)
The following composition was dissolved in 107 parts by mass of methyl ethyl ketone to prepare a coating solution.
Discotic liquid crystalline compound (1) having the above structure 41.01 parts by mass Ethylene oxide modified trimethylolpropane triacrylate “V # 360” manufactured by Osaka Organic Chemical Co., Ltd. 4.06 parts by mass Cellulose acetate butyrate 0.34 parts by mass “ CAB551-0.2 ”manufactured by Eastman Chemical Co., Ltd. Cellulose acetate butyrate 0.11 parts by mass“ CAB531-1 ”manufactured by Eastman Chemical Co., Ltd. Structured fluoroaliphatic group-containing polymer 1 0.03 parts by mass The following structural fluoroaliphatic groups Containing polymer 2 0.23 parts by mass Photopolymerization initiator 1.35 parts by mass “Irgacure 907” manufactured by Ciba Geigy Co., Ltd. Sensitizer 0.45 parts by mass “Kayacure DETX” manufactured by Nippon Kayaku Co., Ltd.

Example 4
In Example 1, an optical compensation sheet (4) was produced in the same manner as in Example 1 except that the coating means for the optically anisotropic layer was changed to the slot die coating method and transported at 40 m / min.

Example 14
In Example 11, instead of using the optical compensation sheet (1), a polarizing plate (P-4) was produced in the same manner as in Example 11 except that this optical compensation sheet (4) was used. As in the case of Example 11, when the performance was evaluated by being attached to a liquid crystal display device, it was confirmed that the viewing angle display characteristics were also good as in Example 11.

Claims (11)

A liquid crystal display device having a TN (twisted nematic) alignment mode liquid crystal cell and a pair of polarizing plates disposed on both sides of the liquid crystal cell,
An optical compensation sheet is disposed between the polarizing film of at least one polarizing plate and the liquid crystal cell,
The optical compensation sheet is
(1) a transparent film that satisfies the following mathematical formulas (1) and (2);
(2) an optically anisotropic layer containing a liquid crystalline compound and formed by coating;
And at least a liquid crystal display device.
Formula (1): 0 ≦ Re ₆₃₀ ≦ 10 and | Rth ₆₃₀ | ≦ 25
Formula (2): | Re ₄₀₀ −Re ₇₀₀ | ≦ 10 and | Rth ₄₀₀ −Rth ₇₀₀ | ≦ 35
[In the formula, Reλ is a front retardation value (unit: nm) at a wavelength λnm, and Rthλ is a retardation value (unit: nm) in a film thickness direction at a wavelength λnm. ]   The liquid crystal display device according to claim 1, wherein the transparent film is a cellulose acylate film.   The liquid crystal display device according to claim 1, wherein the liquid crystal compound is a discotic liquid crystal compound. The transparent film contains at least one compound that lowers the retardation value (Rthλ) in the film thickness direction in a range that satisfies the following mathematical formulas (3) and (4). Liquid crystal display device.
Formula (3): (Rthλ _A −Rthλ ₀ ) /A≦−1.0
Formula (4): 0.01 ≦ A ≦ 30
here,
Rthλ _A : Rthλ (nm) of a film containing A mass% of a compound that lowers Rthλ,
Rthλ ₀ : Rthλ (nm) of a film not containing a compound that reduces Rthλ,
A: The mass (%) of the compound that reduces Rthλ when the mass of the film raw material polymer is 100,
It is.   The cellulose acylate film is a film comprising cellulose acylate having an acyl substitution degree of 2.85 to 3.00, and the cellulose acylate film comprises at least one compound that reduces Reλ and Rthλ, The liquid crystal display device according to any one of claims 2 to 4, comprising 0.01 to 30% by mass with respect to the solid content of cellulose acylate. The cellulose acylate film contains 0.01 to 30% by mass of at least one compound that lowers | Re ₄₀₀ -Re ₇₀₀ | and | Rth ₄₀₀ -Rth ₇₀₀ | with respect to the solid content of cellulose acylate. The liquid crystal display device in any one of -5.   The liquid crystal display device according to claim 1, wherein the transparent film has a thickness of 10 to 120 μm.   An optical compensation sheet used in the liquid crystal display device according to claim 1.   A polarizing plate comprising the optical compensation sheet according to claim 8 as a protective film on at least one surface. (1) a cellulose acylate film satisfying the following mathematical formulas (1) and (2);
(2) an optically anisotropic layer containing a liquid crystalline compound and formed by coating;
And at least an optical compensation sheet.
Formula (1): 0 ≦ Re ₆₃₀ ≦ 10 and | Rth ₆₃₀ | ≦ 25
Formula (2): | Re ₄₀₀ −Re ₇₀₀ | ≦ 10 and | Rth ₄₀₀ −Rth ₇₀₀ | ≦ 35
[In the formula, Reλ is a front retardation value (unit: nm) at a wavelength λnm, and Rthλ is a retardation value (unit: nm) in a film thickness direction at a wavelength λnm. ]   A polarizing plate comprising the optical compensation sheet according to claim 10 as a protective film on at least one surface.