JP2012003209A - Optical compensation film, and polarizing plate and liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce frame-like light leakage of a TN mode liquid crystal display device.SOLUTION: A TN mode liquid crystal display device includes: a pair of polarizers (11 and 12) disposed so that respective polarization axes are orthogonal to each other; a TN mode liquid crystal cell (13) disposed between the polarizers; and low-substitution degree layers including, as a main component, a cellulose acylate satisfying 2.0<Z1<2.7 where Z1 is a total acyl substitution degree of the cellulose acylate in the low-substitution degree layers. In the TN mode liquid crystal display device, the low-substitution degree layer is provided between each of the pair of polarizers and the TN mode liquid crystal cell, and the low-substitution degree layer is provided on an outer surface of each of the pair of polarizers.

Description

  The present invention relates to an optical compensation film, and a polarizing plate and a liquid crystal display device using the same.

  Usually, in a liquid crystal display device, a cellulose acetate film or the like is disposed as a protective film for protecting a polarizer. In recent years, there is a strong demand for thinning liquid crystal display devices, and it is necessary to reduce the thickness of the entire display device. Therefore, the distance between the liquid crystal panel unit and the backlight unit becomes closer, the optical film etc. is distorted by the heat from the backlight, a phase difference occurs at the edge of the liquid crystal display device, and the frame-like light is displayed during black display. There is a problem of leakage. As means for solving this problem, it has been proposed to set the photoelastic coefficient of the pressure-sensitive adhesive layer used in the production of the polarizing plate within a predetermined range (for example, Patent Documents 1 and 2).

  Various optical compensation films having an optically anisotropic layer formed by fixing the orientation of a liquid crystal composition on a support such as a polymer film have been conventionally known as optical compensation for liquid crystal display devices of various modes. ing. The optical compensation film having this structure is generally formed by coating an optically anisotropic layer. When an optical compensation film having an optically anisotropic layer with low surface uniformity is used, display characteristics may be made nonuniform, and the uniformity of the optically anisotropic layer is important.

  On the other hand, as a protective film for a polarizing plate used in a liquid crystal display device or the like, it has been proposed to use cellulose acylate having a low degree of acyl substitution as a material (for example, Patent Document 3).

JP 2006-91254 A JP 2006-208465 A JP 2009-265598 A

  The present invention has been made in view of the above problems, and it is an object of the present invention to reduce frame-like light leakage that occurs during black display of a liquid crystal display device and to improve display uniformity.

Means for solving the above problems are as follows.
[1] An optical compensation comprising a low-substitution layer containing, as a main component, cellulose acylate satisfying the following formula (1), and an optically anisotropic layer comprising a composition containing a polymerizable liquid crystal compound the film.
(1) 2.0 <Z1 <2.7
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the low substitution degree layer.)
[2] The low substitution degree layer has an in-plane retardation Re (550) of -50 to 200 nm at a wavelength of 550 nm, and a thickness direction retardation Rth (550) of 550 nm to 0 to 250 nm. The optical compensation film according to [1].
[3] The optical compensation film according to [1] or [2], wherein the polymerizable liquid crystal compound is a discotic liquid crystal compound.
[4] The optical compensation film according to any one of [1] to [3], wherein the low substitution degree layer further includes a non-phosphate ester compound.

[5] Any one of [1] to [4], wherein at least one surface of the low substitution degree layer has a high substitution degree layer containing cellulose acylate satisfying the following formula (2) as a main component. Optical compensation film.
(2) 2.7 <Z2
(In formula (2), Z2 represents the total acyl substitution degree of the cellulose acylate of the high substitution degree layer.)
[6] The optical compensation film according to [5], wherein the low substitution degree layer and the high substitution degree layer are laminated by co-casting.
[7] The high substitution degree layer contains a non-phosphate ester compound as an additive, and the ratio (part by mass) of the additive to the cellulose acylate contained in the high substitution degree layer is the low substitution degree. The optical compensation film according to [5] or [6], wherein the amount is less than a ratio (parts by mass) of the additive to cellulose acylate contained in the layer.
[8] The optical compensation film according to any one of [4] to [7], wherein the non-phosphate ester compound is a polyester compound containing an aromatic ring.
[9] The optical compensation film according to any one of [1] to [8], wherein the cellulose acylate contained in the low substitution layer satisfies the following formulas (3) to (5).
Formula (3) 1.0 <X1 <2.7
Formula (4) 0 <= Y1 <1.5
Formula (5) X1 + Y1 = Z1
(In the formulas (3), (4) and (5), X1 represents the degree of substitution of the acetyl group of the cellulose acylate of the low-substituted layer, and Y1 has 3 or more carbon atoms of the cellulose acylate of the low-substituted layer. The total substitution degree of acyl groups is represented, and Z1 represents the total acyl substitution degree of cellulose acylate in the low substitution layer.)
[10] The optical compensation film according to any one of [5] to [9], wherein the cellulose acylate used in the high substitution degree layer satisfies the following formulas (6) to (8).
Formula (6) 1.2 <X2 <3.0
Formula (7) 0 <= Y2 <1.5
Formula (8) X2 + Y2 = Z2
(In the formulas (6), (7) and (8), X2 represents the substitution degree of the acetyl group of the cellulose acylate of the high substitution degree layer, and Y2 has 3 or more carbon atoms of the cellulose acylate of the high substitution degree layer. The total substitution degree of acyl groups is represented, and Z2 represents the total acyl substitution degree of cellulose acylate in the high substitution degree layer.
[11] Any one of [1] to [10], wherein the acyl group of the cellulose acylate contained in the low substitution layer and / or the high substitution layer has 2 to 4 carbon atoms. Optical compensation film.
[12] The optical compensation film according to any one of [1] to [11], wherein the cellulose acylate contained in the low substitution layer and / or the high substitution layer is cellulose acetate.
[13] In-plane retardation Re (550) at a wavelength of 550 nm is 10 to 200 nm, and in a plane orthogonal to the in-plane slow axis, a wavelength 550 nm in a direction inclined by ± 40 degrees from the normal direction. Retardations R [+ 40 °] and R [−40 °] are represented by the following formulas (I) and (I ′)
When R [+ 40 °]> R [−40 °] 1.1 ≦ R [+ 40 °] / R [−40 °] ≦ 10 (I)
When R [+ 40 °] <R [−40 °] 1.1 ≦ R [−40 °] / R [+ 40 °] ≦ 10 (I ′)
The optical compensation film according to any one of [1] to [12], wherein

[14] A polarizing plate having at least a polarizer and the optical compensation film according to any one of [1] to [13].
[15] A pair of polarizers arranged with their polarization axes orthogonal to each other, a liquid crystal cell arranged therebetween, and a pair of polarizers between the liquid crystal cell and [1] to [13] A liquid crystal display device comprising any one of the optical compensation films.
[16] The liquid crystal display device according to [15], which is a twisted alignment mode.
[17] The low-substitution layer containing, as a main component, cellulose acylate satisfying the following formula (1) is provided on at least one outer surface of the pair of polarizers [15] or [16] Liquid crystal display device.
(1) 2.0 <Z1 <2.7
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the low substitution degree layer.)
[18] At least one selected from a cyclic olefin resin, a polyolefin resin, a polyester resin, a polycarbonate resin, an acrylate resin, and a cellulose acylate resin on at least one outer surface of a pair of polarizers. A liquid crystal display device according to any one of [15] to [17], comprising a film containing the liquid crystal display device.

  According to the present invention, it is possible to reduce frame-like light leakage that occurs during black display of a TN mode liquid crystal display device and to improve display uniformity.

It is a schematic sectional drawing of an example of the liquid crystal display device of this invention. It is the schematic which shows an example when the low substitution degree cellulose acylate type | system | group film of a 3 layer structure is poured by simultaneous co-casting using a co-casting die.

Hereinafter, the present invention will be described in detail. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured with KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.) by making light having a wavelength of λ nm incident in the normal direction of the film. In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like. When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method. This measuring method is also partially used for measuring the average tilt angle on the alignment film side of the discotic liquid crystal molecules in the optically anisotropic layer, which will be described later, and the average tilt angle on the opposite side.
Rth (λ) is the film surface when Re (λ) is used and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) (if there is no slow axis) Measurement is performed at a total of 6 points by injecting light of wavelength λ nm from each inclined direction in steps of 10 degrees from the normal direction to 50 ° on one side with respect to the film normal direction (with any rotation direction as the rotation axis). Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value. In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative. The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Rth can also be calculated from the following formula (A) and formula (III) based on the value, the assumed value of the average refractive index, and the input film thickness value.

なお、上記のＲｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値をあらわす。また、式（Ａ）におけるｎｘは、面内における遅相軸方向の屈折率を表し、ｎｙは、面内においてｎｘに直交する方向の屈折率を表し、ｎｚは、ｎｘ及びｎｙに直交する方向の屈折率を表す。
Ｒｔｈ＝｛（ｎｘ＋ｎｙ）／２−ｎｚ｝×ｄ・・・・・・・・・・・式（ＩＩＩ）

Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula (A), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz is the direction orthogonal to nx and ny. Represents the refractive index.
Rth = {(nx + ny) / 2−nz} × d (formula (III))

When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method. Rth (λ) is from −50 ° to the normal direction of the film, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis). Measured at 11 points by making light of wavelength λ nm incident in 10 ° steps up to + 50 °, and based on the measured retardation value, average refractive index assumption value and input film thickness value. KOBRA 21ADH or WR is calculated. In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

The “slow axis” means the direction in which the refractive index is maximized, and the measurement wavelength of the refractive index is a value in the visible light region (λ = 550 nm) unless otherwise specified.
In addition, in this specification, numerical values, numerical ranges, and qualitative expressions (for example, expressions such as “equivalent” and “equal”) indicating the optical characteristics of each member such as an optical film and a liquid crystal layer are liquid crystal displays. It shall be construed to indicate numerical values, numerical ranges and properties including generally acceptable errors for the device and the components used therein.

  The present invention relates to an optical compensation film having a low-substitution layer containing, as a main component, a cellulose acylate having a low substitution degree that satisfies a predetermined condition, and an optically anisotropic layer comprising a composition containing a polymerizable liquid crystal compound The present invention relates to a TN mode liquid crystal display device including As a result of investigation by the present inventors, a low substitution degree layer containing a cellulose acylate having a low substitution degree that satisfies a predetermined condition as a main component has optical characteristics required for the support of the optical compensation film having the above-described configuration. Compared with a conventional layer containing cellulose acylate having a high degree of substitution as a main component, it can be achieved with a thinner layer. Since the TN mode liquid crystal display device of the present invention includes the optical compensation film using the low substitution degree layer as a support, the thickness of the liquid crystal panel unit can be reduced as compared with the conventional one. The distortion of the liquid crystal panel and the polarizing plate due to heat or the like can be reduced, and the frame-shaped light leakage that occurs during black display can be reduced.

  In order to obtain the effects of the present invention, it is sufficient that the thickness of the low substitution degree layer is 80 μm or less, more preferably 70 μm or less, and further preferably 60 μm or less. Although there is no restriction | limiting in particular about a lower limit, Generally 30 micrometers or more are preferable.

  Furthermore, as a result of intensive studies by the present inventors, the low substitution layer is characterized in that it has higher hydrophilicity than a conventional layer containing cellulose acylate having a high substitution degree as a main component. When forming the optically anisotropic layer, an alignment film is usually used, and the alignment film is often formed by coating using a hydrophilic material such as polyvinyl alcohol. When a hydrophilic material is applied to the surface of a hydrophobic polymer film, the uniformity of the coating film is impaired, and as a result, the surface uniformity of the optically anisotropic layer formed thereon may be impaired. . When an optical compensation film having a low surface uniformity is used in a liquid crystal display device, the disturbance of the surface uniformity is reflected in the display characteristics, and the display uniformity may be impaired. In the present invention, an alignment film can be formed on a relatively highly hydrophilic low-substitution layer, so that the surface uniformity of the alignment film and the optically anisotropic layer formed thereon can be reduced. . Therefore, since the liquid crystal display device of the present invention includes the optical compensation film having high surface uniformity, the liquid crystal display device exhibits high uniformity display characteristics.

FIG. 1 is a schematic cross-sectional view of an example of the liquid crystal display device of the present invention. The liquid crystal display device of FIG. 1 includes a pair of polarizers 11 and 12 and a TN mode liquid crystal cell 13 disposed therebetween. An optical compensation film 20 is disposed between the liquid crystal cell 13 and the polarizer 11, and an optical compensation film 21 is disposed between the liquid crystal cell 13 and the polarizer 12. The polarizers 11 and 12 are arranged with their polarization axes orthogonal to each other. The liquid crystal cell 13 is a TN mode driven by rising of liquid crystal molecules, and the rubbing directions applied to the inner surface of the cell substrate (not shown) are orthogonal to each other. Outside protective films 18 and 19 made of a polymer film such as a cellulose acylate film are disposed outside the polarizers 11 and 12, respectively.
The same effect can be obtained regardless of whether the display surface is on the upper side or the lower side in the figure.

  The optical compensation films 20 and 21 have optically anisotropic layers 15 and 17 made of a composition containing a polymerizable liquid crystal compound, respectively. A liquid crystal layer (not shown) included in the liquid crystal cell 13 is a layer formed by filling a nematic liquid crystal material having a positive dielectric anisotropy. The liquid crystal molecules are arranged in the vicinity of the upper and lower cell substrates by a horizontal alignment film. When the alignment direction is defined and no electric field is applied between the electrode layers, the upper and lower substrates are twisted with a twist angle of substantially 90 °. On the other hand, when a voltage for black display is applied between the electrodes, the liquid crystal molecules rise perpendicularly to the surfaces of the upper and lower substrates and are aligned at a predetermined average tilt angle θ (about 60 ° to 90 °). In that state, the polarization state of the light propagating in the liquid crystal layer differs depending on the orientation of the liquid crystal molecules between the case where the light is incident on the liquid crystal layer from the normal direction and the case where the light is incident from an oblique direction. As a result, the contrast is lowered depending on the viewing angle, and gradation inversion and color shift occur. In the liquid crystal display device of FIG. 1, the optical compensation films 20 and 21 (particularly the optically anisotropic layers 15 and 17) arranged above and below the liquid crystal cell 13 reduce the viewing angle dependency of display characteristics such as contrast, The viewing angle characteristics are improved. From the viewpoint of optical compensation, the optically anisotropic layers 15 and 17 preferably contain a liquid crystal compound in a hybrid alignment state, and particularly preferably contain a discotic liquid crystal compound in a hybrid alignment state. The polymerizable liquid crystal compound is more preferably fixed in a desired alignment state by advancing a polymerization reaction.

Each of the optical compensation films 20 and 21 is a support for the optically anisotropic layers 15 and 17, and is an inner protective film for the polarizers 11 and 12, and is mainly composed of cellulose acylate satisfying the following formula (I). Low substitution layers 14 and 16 included as
(1) 2.0 <Z1 <2.7
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the low substitution degree layer.)

  In this embodiment, it is preferable that the low substitution degree layers constituting the inner protective films 14 and 16 exhibit the same optical characteristics. In this aspect, the inner protective films 14 and 16 may or may not contribute to the optical compensation of the TN mode liquid crystal cell. Specifically, Re (550) is preferably −50 to 200 nm, and Rth (550) is preferably 0 to 250 nm.

  In this embodiment, the outer protective films 18 and 19 are not particularly limited. For example, a triacetyl cellulose (TAC) film conventionally used for a protective film for a polarizing plate can be used. Commercial products may be used. In this embodiment, it is preferable that the outer protective films 18 and 19 are composed of the predetermined low substitution degree layer. The outer protective films 18 and 19 do not contribute to the optical compensation of the TN mode liquid crystal cell, and the optical characteristics are not particularly limited.

Also in the said aspect, the said low substitution degree layer may be integrated with another layer and may comprise the outer protective film or inner protective film of a polarizer. For example, a high substitution degree layer containing a cellulose acylate satisfying the following formula (2) as a main component is laminated on one side or both sides of the low substitution degree layer and used as an outer protective film or an inner protective film. You can also
(2) 2.7 <Z2
(In formula (2), Z2 represents the total acyl substitution degree of the cellulose acylate of the high substitution degree layer.)
However, in an embodiment in which a laminate with a high substitution degree layer is used for the inner protective films 14 and 16, the high substitution degree layer on the surface side of the band during film production is peeled off from the band surface. Is preferable from the viewpoint of production stability. In order not to impair the effects of the present invention, the high substitution layer is preferably thinner than the low substitution layer, specifically 10 μm or less. The low substitution layer and the high substitution layer are preferably laminated using a co-casting method.

  The liquid crystal display device of FIG. 1 has a liquid crystal cell 13 as a polarizing plate 22 (23) in which an outer protective film 18 (19), a polarizer 11 (12), and an optical compensation film 20 (21) are laminated and integrated. It may be produced by pasting.

Hereinafter, various members usable for the liquid crystal display device of the present invention will be described.
Optical compensation film:
The present invention also relates to an optical compensation film having a low-substitution layer containing, as a main component, cellulose acylate satisfying the following formula (I), and an optically anisotropic layer comprising a composition containing a polymerizable liquid crystal compound. . The optical compensation film of the present invention has each between a liquid crystal cell and a pair of polarizers.
Hereinafter, each member which comprises an optical compensation film is demonstrated in detail.

Low substitution layer:
A low-substitution layer containing, as a main component, cellulose acylate satisfying the following formula (I) is provided as a support for an optically anisotropic layer made of a liquid crystal composition. Moreover, it is preferable that the said low substitution degree layer is utilized also as an inner side protective film of a polarizer.
(1) 2.0 <Z1 <2.7
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the low substitution degree layer.)
In the present specification, “contains as a main component” means an ingredient having the highest mass fraction in an embodiment in which the component as a raw material is one kind, and an ingredient having two or more ingredients. To do.

As described above, the substitution degree layer may have a high substitution degree layer containing, as a main component, cellulose acylate satisfying the following formula (2) on at least one surface thereof.
(2) 2.7 <Z2
(In formula (2), Z2 represents the total acyl substitution degree of the cellulose acylate of the high substitution degree layer.)

(Cellulose acylate)
Examples of the cellulose acylate used for the production of the low substitution layer and the high substitution layer include cotton linter and wood pulp (hardwood pulp, conifer pulp), and cellulose acylate obtained from any raw material cellulose is used. In some cases, a mixture may be used. Detailed descriptions of these raw material celluloses can be found, for example, by Marusawa and Uda, “Plastic Materials Course (17) Fibrous Resin”, published by Nikkan Kogyo Shimbun (published in 1970), and the Japan Institute of Invention and Technology Publication No. 2001 The cellulose described in No.-1745 (pages 7 to 8) can be used.

  The raw material cellulose acylate used for the production of the low-substitution layer and the high-substitution layer is acylated with two or more types of acyl groups, even if it is acylated with one type of acyl group. It may be. It is preferable to have an acyl group having 2 to 4 carbon atoms as a substituent. When two or more types of acyl groups are used, one of them is preferably an acetyl group, and the acyl group having 2 to 4 carbon atoms is preferably a propionyl group or a butyryl group. With these films, a solution having a preferable solubility can be prepared, and in particular, in a non-chlorine organic solvent, a good solution can be prepared. Furthermore, a solution having a low viscosity and good filterability can be prepared.

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by acylating part or all of these hydroxyl groups with an acyl group. The degree of acyl substitution means the sum of the ratios of acylation of the hydroxyl groups of cellulose located at the 2-position, 3-position and 6-position (100% acylation at each position is substitution degree 1).

  The acyl group having 2 or more carbon atoms may be an aliphatic group or an allyl group, and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferred examples of these include acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, isobutanoyl group Group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, an acetyl group, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a tert-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and an acetyl group is particularly preferable. A propionyl group and a butanoyl group (when the acyl group has 2 to 4 carbon atoms), more preferably an acetyl group (when the cellulose acylate is cellulose acetate).

  In the acylation of cellulose, when an acid anhydride or acid chloride is used as an acylating agent, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent.

As the catalyst, when the acylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acylating agent is an acid chloride (for example, CH ₃ CH ₂ COCl), Basic compounds are used.

  The most common industrial synthesis method of cellulose mixed fatty acid ester is to use cellulose corresponding to fatty acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, valeric acid, etc.) or their anhydrides. This is a method of acylating with a mixed organic acid component.

In the present invention, it is preferable from the viewpoint of wavelength dispersion of retardation that the acylose acylate used for forming the low substitution layer satisfies the following formulas (3) and (4).
Formula (3) 1.0 <X1 <2.7
(In Formula (3), X1 represents the substitution degree of the acetyl group of the cellulose acylate in the low substitution degree layer.)
Formula (4) 0 <= Y1 <1.5
(In Formula (4), Y1 represents the total substitution degree of acyl groups having 3 or more carbon atoms in the cellulose acylate of the low substitution degree layer.)
Note that the relationship X1 + Y1 = Z1 holds between X1 and Y1 and Z1 in the formula (1).

Moreover, it is preferable from a viewpoint of the wavelength dispersibility of a retardation that the cellulose acylate used for formation of the said high substitution degree layer satisfy | fills following formula (5) and (6).
Formula (5) 1.2 <X2 <3.0
(In Formula (5), X2 represents the substitution degree of the acetyl group of the cellulose acylate in the high substitution degree layer.)
Formula (6) 0 <= Y2 <1.5
(In Formula (6), Y2 represents the total substitution degree of acyl groups having 3 or more carbon atoms in the cellulose acylate of the high substitution degree layer.)
Note that the relationship of X2 + Y2 = Z2 holds between X2 and Y2 and Z2 in the formula (2).

  The cellulose acylate used in the present invention can be synthesized, for example, by the method described in JP-A-10-45804.

(Non-phosphate compound)
It is preferable that a non-phosphate ester compound is contained in the low substitution degree layer (more preferably also in the high substitution degree layer). By including such a non-phosphate ester compound, there is an effect of reducing the haze.
In the present specification, the “non-phosphate ester compound” refers to a “compound having an ester bond and the acid contributing to the ester bond other than phosphoric acid”. That is, the “non-phosphate ester compound” means a compound that does not contain phosphoric acid and is an ester compound.
Further, the non-phosphate ester compound may be a low molecular compound or a polymer (polymer compound). Hereinafter, a non-phosphate ester compound which is a polymer (polymer compound) is also referred to as a non-phosphate ester polymer.

  The high substitution degree layer contains the non-phosphate ester compound as an additive, and the ratio (part by mass) of the additive to the cellulose acylate contained in the high substitution degree layer is in the low substitution degree layer. Less than the ratio (parts by mass) of the additive to the cellulose acylate contained is preferable from the viewpoint of reducing haze. Hereinafter, the non-phosphate ester compounds that can be used in the present invention will be described.

  As the non-phosphate ester compound, known high molecular weight additives and low molecular weight additives can be widely employed as additives for cellulose acylate films. The content of the additive is preferably 1 to 35% by mass, more preferably 4 to 30% by mass, and still more preferably 10 to 25% by mass with respect to the cellulose acylate.

  The high molecular weight additive used as the non-phosphate ester compound has a repeating unit in the compound and preferably has a number average molecular weight of 700 to 10,000. The high molecular weight additive has a function of increasing the volatilization rate of the solvent and a function of reducing the residual solvent amount in the solution casting method. Furthermore, it exhibits useful effects from the viewpoint of film modification such as improvement in mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability.

Here, the number average molecular weight of the high molecular weight additive which is a non-phosphate ester compound in the present invention is more preferably a number average molecular weight of 700 to 8000, still more preferably a number average molecular weight of 700 to 5000, The number average molecular weight is preferably 1000 to 5000.
Hereinafter, the high molecular weight additive which is a non-phosphate ester compound that can be used in the present invention will be described in detail with specific examples. However, the high-phosphate additive that is a non-phosphate ester compound used in the present invention is described below. Needless to say, the molecular weight additives are not limited to these.
The non-phosphate ester compound is preferably a non-phosphate ester compound. However, the “non-phosphate ester-based compound” means a compound that does not contain a phosphate ester and is ester-based.

  Examples of the polymer additive that is a non-phosphate ester compound include polyester polymers (aliphatic polyester polymers, aromatic polyester polymers, etc.), copolymers of polyester components and other components, and the like. , Aliphatic polyester polymer, aromatic polyester polymer, polyester polymer (aliphatic polyester polymer, aromatic polyester polymer, etc.) and acrylic polymer and polyester polymer (aliphatic polyester polymer, aromatic A copolymer of an aromatic polyester polymer or the like) and a styrene polymer is preferable, and a polyester compound containing an aromatic ring as at least one of the copolymer components is more preferable.

  Examples of the aliphatic polyester-based polymer include at least one diol selected from aliphatic dicarboxylic acids having 2 to 20 carbon atoms, aliphatic diols having 2 to 12 carbon atoms, and alkyl ether diols having 4 to 20 carbon atoms. The both ends of the reaction product may be left as the reaction product, or the monocarboxylic acid, monoalcohol or phenol may be further reacted to carry out so-called end-capping. Good. It is effective in terms of storage stability that the end capping is performed in particular so as not to contain free carboxylic acids. The dicarboxylic acid used in the polyester polymer of the present invention is preferably an aliphatic dicarboxylic acid residue having 4 to 20 carbon atoms or an aromatic dicarboxylic acid residue having 8 to 20 carbon atoms.

  Examples of the aliphatic dicarboxylic acid having 2 to 20 carbon atoms preferably used in the present invention include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid. , Sebacic acid, dodecanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.

  Among these, preferable aliphatic dicarboxylic acids are malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, and 1,4-cyclohexanedicarboxylic acid. Particularly preferably, the aliphatic dicarboxylic acid component is succinic acid, glutaric acid, or adipic acid.

  The diol utilized for the high molecular weight additive is selected from, for example, an aliphatic diol having 2 to 20 carbon atoms and an alkyl ether diol having 4 to 20 carbon atoms.

  Examples of the aliphatic diol having 2 to 20 carbon atoms include alkyl diols and alicyclic diols, such as ethane diol, 1,2-propanediol, 1,3-propanediol, and 1,2-butane. Diol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) ), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3 -Methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Used as a mixture of two or more.

  Preferred aliphatic diols include ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1 , 4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, particularly preferred Is ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

  Preferred examples of the alkyl ether diol having 4 to 20 carbon atoms include polytetramethylene ether glycol, polyethylene ether glycol and polypropylene ether glycol, and combinations thereof. The average degree of polymerization is not particularly limited, but is preferably 2 to 20, more preferably 2 to 10, further 2 to 5, and particularly preferably 2 to 4. As examples of these, commercially useful polyether glycols typically include Carbowax resin, Pluronics resin and Niax resin.

In the present invention, a high molecular weight additive whose end is sealed with an alkyl group or an aromatic group is particularly preferable. This is because the terminal is protected with a hydrophobic functional group, which is effective against deterioration with time at high temperature and high humidity, and is due to the role of delaying hydrolysis of the ester group.
It is preferable to protect with a monoalcohol residue or a monocarboxylic acid residue so that both ends of the polyester additive of the present invention are not carboxylic acid or OH group.
In this case, the monoalcohol is preferably a substituted or unsubstituted monoalcohol having 1 to 30 carbon atoms, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol. , Octanol, isooctanol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, aliphatic alcohol such as dodecaoctanol, allyl alcohol, oleyl alcohol, benzyl alcohol, 3-phenyl Examples thereof include substituted alcohols such as propanol.

  End-capping alcohols that can be preferably used are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, isooctanol, 2-ethylhexyl alcohol, isononyl alcohol, oleyl alcohol Benzyl alcohol, in particular methanol, ethanol, propanol, isobutanol, cyclohexyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, benzyl alcohol.

  Moreover, when sealing with a monocarboxylic acid residue, the monocarboxylic acid used as a monocarboxylic acid residue is preferably a substituted or unsubstituted monocarboxylic acid having 1 to 30 carbon atoms. These may be aliphatic monocarboxylic acids or aromatic ring-containing carboxylic acids. Preferred aliphatic monocarboxylic acids are described, for example, acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, and examples of the aromatic ring-containing monocarboxylic acid include Benzoic acid, p-tert-butylbenzoic acid, p-tert-amylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc. Yes, these can be used alone or in combination of two or more.

  The synthesis of the high molecular weight additive may be a hot melt condensation method using a polyesterification reaction or a transesterification reaction between the aliphatic dicarboxylic acid and a diol and / or a monocarboxylic acid or monoalcohol for end-capping by a conventional method. Alternatively, it can be easily synthesized by any of the interfacial condensation methods of acid chlorides of these acids and glycols. These polyester-based additives are described in detail in Koichi Murai, “Additives, Theory and Application” (Kokaibo Co., Ltd., first edition published on March 1, 1973). In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 2007-003679. The materials described in each publication can also be used.

The aromatic polyester polymer is obtained by copolymerizing a monomer having an aromatic ring with the polyester polymer. The monomer having an aromatic ring is at least one monomer selected from aromatic dicarboxylic acids having 8 to 20 carbon atoms and aromatic diols having 6 to 20 carbon atoms.
Examples of the aromatic dicarboxylic acid having 8 to 20 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8- There are naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid. Among these, preferable aromatic dicarboxylic acids are phthalic acid, terephthalic acid, and isophthalic acid.

  Examples of the aromatic diol having 6 to 20 carbon atoms include, but are not limited to, bisphenol A, 1,2-hydroxybenzene, 1,3-hydroxybenzene, 1,4-hydroxybenzene, and 1,4-benzenedimethanol. Bisphenol A, 1,4-hydroxybenzene and 1,4-benzenedimethanol are preferred.

  In the present invention, the aromatic polyester-based polymer is used by combining at least one of each of aromatic dicarboxylic acid and aromatic diol with the above-mentioned polyester, but the combination is not particularly limited, and each component is not limited. There is no problem even if several types are combined. In the present invention, as described above, a high molecular weight additive whose end is sealed with an alkyl group or an aromatic group is particularly preferable, and the above-described method can be used for sealing.

<Other additives>
Examples of additives other than the non-phosphate ester compounds include retardation adjusting agents (retardation developing agents and retardation reducing agents); plasticizers such as phthalate esters and phosphate esters; ultraviolet absorbers; antioxidants; Additives such as matting agents can also be added.

  In the present invention, compounds other than phosphoric acid ester compounds and known non-phosphoric acid ester compounds as additives for cellulose acylate films can be widely employed as retardation reducing agents.

  The polymer retardation reducing agent is selected from phosphoric acid-based polyester polymers, styrene polymers, acrylic polymers, and copolymers thereof, and acrylic polymers and styrene polymers are preferred. Moreover, it is preferable that at least one polymer having negative intrinsic birefringence, such as a styrene polymer and an acrylic polymer, is included.

  Examples of the low molecular weight retardation reducing agent which is a compound other than the non-phosphate ester compound include the following. These may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and a mixture of deterioration preventing agents are also possible. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the cellulose acylate solution (dope) preparation step, but it may be added by adding a preparation step to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested.

  The low molecular weight retardation reducing agent which is a compound other than the non-phosphate ester compound is not particularly limited, but details are described in JP-A-2007-272177, [0066] to [0085].

The compound described as the general formula (1) in [0066] to [0085] of JP-A-2007-272177 can be prepared by the following method.
The compound of the general formula (1) of the publication can be obtained by a condensation reaction between a sulfonyl chloride derivative and an amine derivative.

  JP, 2007-272177, A The compound of general formula (2) is a dehydration condensation reaction of carboxylic acids and amines using a condensing agent (for example, dicyclohexylcarbodiimide (DCC) etc.), or a carboxylic acid chloride derivative, It can be obtained by a substitution reaction with an amine derivative.

  The retardation reducing agent may be an Rth reducing agent. Among the retardation reducing agents, examples of the Rth reducing agent include acrylic polymers and styrene polymers, and low molecular compounds of the general formulas (3) to (7). Among them, acrylic polymers and styrene polymers. Polymers are preferred, and acrylic polymers are more preferred.

The retardation reducing agent is preferably added in a proportion of 0.01 to 30% by mass, more preferably 0.1 to 20% by mass, more preferably 0.1 to 10%, based on cellulose acylate. It is particularly preferable to add at a ratio of mass%.
By making the said addition amount 30 mass% or less, compatibility with a cellulose acylate can be improved and whitening can be suppressed. When using two or more types of retardation reducing agents, the total amount is preferably within the above range.

(Plasticizer)
As the plasticizer used in the present invention, many compounds known as cellulose acylate plasticizers can be usefully used. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred.

(Retardation expression agent)
The low-substituted cellulose acylate film preferably contains at least one retardation developer in the low-substituted layer in order to develop a retardation value. Although there is no restriction | limiting in particular as said retardation developing agent, The compound which consists of a rod-shaped or a disk-shaped compound, and the compound which shows retardation expression among the said non-phosphate ester type compounds can be mentioned. As the rod-like or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developer.
The addition amount of the retardation enhancer composed of the rod-shaped compound is preferably 0.1 to 30 parts by mass, and preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Further preferred. The discotic compound contained in the retardation developer is preferably less than 3 parts by mass, more preferably less than 2 parts by mass, and less than 1 part by mass with respect to 100 parts by mass of the cellulose acylate. It is particularly preferred.
Since the discotic compound is superior to the rod-shaped compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required. Two or more retardation developers may be used in combination.
The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

The number of carbon atoms of the aromatic ring in the retardation enhancer is preferably 2-20, more preferably 2-12, still more preferably 2-8, and 2-6. Most preferred.
The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

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

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

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

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

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

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

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

  As the discotic compound, a triazine compound represented by the following general formula (I) is preferably used.

In the above general formula (I):
R ²⁰¹ each independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho position, meta position and para position.
X ²⁰¹ each independently represents a single bond or —NR ²⁰² —. Here, each R ²⁰² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ²⁰¹ is preferably phenyl or naphthyl, particularly preferably phenyl. The aromatic ring R ²⁰¹ represents may have at least one substituent at any substitutable position. Examples of the substituent include halogen atom, hydroxyl group, cyano group, nitro group, carboxyl group, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, Alkenyloxycarbonyl group, aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide Groups, alkylthio groups, alkenylthio groups, arylthio groups and acyl groups.

The heterocyclic group represented by ^R201 preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.
When X ²⁰¹ is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. Further, the heterocyclic group may have a hetero atom other than the nitrogen atom (for example, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below. Here, -C ₄ H ₉ ⁿ represents a n-C ₄ H _9.

The alkyl group represented by R ²⁰² may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, further preferably 1-10, still more preferably 1-8, and 1-6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy group, ethoxy group) and an acyloxy group (for example, acryloyloxy group, methacryloyloxy group).

The alkenyl group represented by R ²⁰² may be a cyclic alkenyl group or a chain alkenyl group, but is preferably a chain alkenyl group and is more preferably a linear alkenyl group than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.
The aromatic ring group and heterocyclic group represented by R ²⁰² are the same as the aromatic ring and heterocyclic ring represented by R ²⁰¹ , and the preferred range is also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of ^R201 .

  The compound represented by the general formula (I) can be synthesized by a known method such as the method described in JP-A-2003-344655. Details of the retardation enhancer are described on page 49 of published technical bulletin 2001-1745.

  As the retardation developer of the present invention, a polymer additive can be used as in the case of the low molecular compound. Here, in the present invention, the polymer used as the non-phosphate ester-based polymer may also function as a retardation developer. As the polymeric retardation developer which is also a non-phosphate ester polymer, the aromatic polyester polymer and copolymers of the aromatic polyester polymer and other resins are preferable.

  The retardation enhancer of the present invention is more preferably a Re enhancer from the viewpoint of efficiently expressing Re and realizing an appropriate Nz factor. Among the retardation developing agents, examples of the Re developing agent include a discotic compound and a rod-shaped compound.

  In the present invention, deterioration inhibitors, ultraviolet absorbers, peeling accelerators, matting agents, lubricants, the aforementioned plasticizers, and the like can be appropriately used as necessary.

(Deterioration inhibitor)
The low substitution layer and the high substitution layer are deterioration (oxidation) inhibitors such as 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl- 3-methylphenol), 1,1′-bis (4-hydroxyphenyl) cyclohexane, 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, penta Phenolic or hydroquinone antioxidants such as erythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] can be added. Further, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert) It is preferable to use a phosphorus-based antioxidant such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The addition amount of the deterioration inhibitor is 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the cellulose acylate.

(UV absorber)
The low substitution degree layer and the high substitution degree layer may contain an ultraviolet absorber. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specific examples of ultraviolet absorbers preferably used in the present invention include, for example, hindered phenol compounds, hydroxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds Etc. Examples of hindered phenol compounds include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert) -Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. Examples of benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6 (2H-benzotriazol-2-yl) phenol), (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5- Triazine, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4- Hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, (2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5 -Chlorobenzotriazole, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like. The addition amount of these ultraviolet light inhibitors is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm by mass in the entire optical film.

(Peeling accelerator)
The low substitution layer and the high substitution layer may contain a peeling accelerator. For example, when the low-substituted cellulose acylate film is produced by a solution casting method, the peeling accelerator is added to make the peeling of the film from a support such as a band stable and easy. The release accelerator can be included at a ratio of 0.001 to 1% by weight, for example, and if it is added in an amount of 0.5% by weight or less, separation of the release agent from the film is less likely to occur. 005% by weight or more is preferable because a desired peeling reduction effect can be obtained. Therefore, it is preferably included at a rate of 0.005 to 0.5% by weight, and at a rate of 0.01 to 0.3% by weight. More preferably. As the peeling accelerator, known ones can be adopted, and organic and inorganic acidic compounds, surfactants, chelating agents and the like can be used. Among them, polyvalent carboxylic acids and esters thereof are effective, and in particular, ethyl esters of citric acid can be used effectively.
In the aspect in which the low substitution layer is laminated on the high substitution layer, it is preferable that the high substitution layer is on the surface side of a support such as a band. It is preferable to add an agent.

(Matting agent)
It is preferable from the viewpoint of film slipperiness and stable production that at least one of the high substitution layers contains a matting agent. The matting agent may be an inorganic compound matting agent or an organic compound matting agent.
Specific examples of the inorganic compound matting agent include silicon-containing inorganic compounds (for example, silicon dioxide, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, etc.), titanium oxide, and zinc oxide. , Aluminum oxide, barium oxide, zirconium oxide, strongtium oxide, antimony oxide, tin oxide, tin oxide / antimony, calcium carbonate, talc, clay, calcined kaolin, calcium phosphate, etc., more preferably silicon-containing inorganic compounds and oxides Although it is zirconium, since the turbidity of a cellulose acylate film can be reduced, silicon dioxide is particularly preferably used. As the silicon dioxide fine particles, for example, commercially available products having trade names such as Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used. As the zirconium oxide fine particles, for example, those commercially available under trade names such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.
Preferable specific examples of the organic compound matting agent include, for example, polymers such as silicone resin, fluorine resin and acrylic resin, and among them, silicone resin is preferably used. Of the silicone resins, those having a three-dimensional network structure are particularly preferable. A commercial product having a trade name can be used.

  When these matting agents are added to the cellulose acylate solution, the method is not particularly limited, and there is no problem as long as a desired cellulose acylate solution can be obtained by any method. For example, an additive may be contained at the stage of mixing cellulose acylate and a solvent, or an additive may be added after preparing a mixed solution with cellulose acylate and a solvent. Further, it may be added and mixed immediately before casting the dope, which is a so-called immediately preceding addition method, and the mixing is used by installing screw-type kneading online. Specifically, a static mixer such as an in-line mixer is preferable, and as the in-line mixer, for example, a static mixer SWJ (Toray Static In-Pipe Mixer Hi-Mixer) (manufactured by Toray Engineering) is used. Is preferred. In addition, regarding in-line addition, in order to eliminate density unevenness, particle aggregation, and the like, Japanese Patent Application Laid-Open No. 2003-053752 mixes additive liquids having different compositions into the main raw material dope in a method for producing a cellulose acylate film. An invention is described in which the distance L between the tip of the addition nozzle and the start end of the in-line mixer is 5 times or less the inner diameter d of the main raw material pipe, thereby eliminating concentration unevenness and aggregation of matte particles. As a more preferred embodiment, the distance (L) between the tip opening of the additive liquid supply nozzle having a composition different from that of the main raw material dope and the starting end of the in-line mixer is 10 times or less the inner diameter (d) of the supply nozzle tip opening. And that the in-line mixer is a static unstirred in-tube mixer or a dynamic agitated in-tube mixer. More specifically, it is disclosed that the flow rate ratio of the cellulose acylate film main raw material dope / in-line additive solution is 10/1 to 500/1, preferably 50/1 to 200/1. Furthermore, the additive is also added to Japanese Patent Application Laid-Open No. 2003-014933 of the invention which aims at a retardation film with little additive bleed-out, no delamination phenomenon, good slipperiness and excellent transparency. As a method to do this, it may be added to the melting pot, or a solution in which additives or additives are dissolved or dispersed between the melting pot and the co-casting die may be added to the dope being fed. However, in the latter case, it is described that it is preferable to provide a mixing means such as a static mixer in order to improve the mixing property.

In an aspect of the laminate of the low substitution layer and the high substitution layer, it is preferable that the low substitution layer is a core layer, and the high substitution layer is formed on both sides of the core layer. Addition of the matting agent to any of the substitution degree layers is a viewpoint of scratch resistance due to reduction of the coefficient of friction of the film surface, prevention of creaking that occurs when a wide film is wound in a long length, and prevention of film breakage It is particularly preferable from the viewpoint of effectively reducing scratch resistance and creaking.
If the matting agent is not added in a large amount, the haze of the film does not increase. When actually used in an LCD, inconveniences such as a decrease in contrast and generation of bright spots are unlikely to occur. If the amount is too small, the above-mentioned creaking and scratch resistance can be realized. From these viewpoints, it is preferably included in a proportion of 0.01 to 5.0% by weight, more preferably included in a proportion of 0.03 to 3.0% by weight, and a proportion of 0.05 to 1.0% by weight. It is particularly preferable to include

(Haze)
The laminate having the low substitution degree layer or the low substitution degree layer and the high substitution degree layer preferably has a haze of less than 0.20%, more preferably less than 0.15%. It is particularly preferred that it is less than 10%. By setting the haze to less than 0.2%, the contrast ratio when incorporated in a liquid crystal display device can be improved. In addition, there is an advantage that the transparency of the film becomes higher and it is easier to use as an optical film.

  It is preferable that the predetermined low substitution degree layer and the predetermined high substitution degree layer are laminated on at least one surface of the low substitution degree layer. The acyl group substitution degree of cellulose acylate in each layer may be uniform or a plurality of cellulose acylates may be mixed in one layer, but the acyl group substitution degree of cellulose acylate in each layer is all constant. It is preferable from the viewpoint of adjustment of optical characteristics.

  In addition, the layer in contact with the support (hereinafter also referred to as skin B layer) when producing by solution casting is the high substitution layer, and the other layers are the low substitution layer. From the viewpoint of further improving the peelability from the support.

  It is preferable to have a laminated structure of three or more layers from the viewpoint of dimensional stability and curl amount reduction associated with environmental wet heat changes. Moreover, when it has the said high substitution degree layer on both surfaces of the said low substitution degree layer, it is preferable from a viewpoint of the freedom degree improvement in the process of implement | achieving a desired optical characteristic. Furthermore, it has a laminated structure of three or more layers, and the cellulose acylate contained in at least one inner layer is a cellulose acylate satisfying the above formulas (3) and (4), and is contained in both surface layers. More preferably, the cellulose acylate is a cellulose acylate satisfying the above formulas (5) and (6). In addition, only when it has a laminated structure of three or more layers, the surface layer on the side that is not in contact with the support during film formation is also referred to as a skin A layer.

In the present invention, a three-layer structure of skin B layer / core layer / skin A layer is preferable. In the case of a three-layer structure, the structure may be a high substitution layer / low substitution layer / high substitution layer or a low substitution layer / high substitution layer / low substitution layer. The constitution of the substitution degree layer / low substitution degree layer / high substitution degree layer is preferable from the viewpoint of improving peelability from the support during solution casting and from the viewpoint of dimensional stability.
When the cellulose acylate has a three-layer structure, it is preferable to use cellulose acylate having the same acyl substitution degree as the cellulose acylate contained in the surface layers on both sides from the viewpoint of manufacturing cost, dimensional stability, and curl amount reduction due to environmental moist heat change. .

(Film thickness)
The average film thickness of the low substitution layer is preferably 30 to 100 μm, more preferably 30 to 80 μm, and further preferably 30 to 70 μm. By setting it to 30 μm or more, the handling property when producing a web-like film is improved, which is preferable. Moreover, by setting it as 70 micrometers or less, it is easy to respond to a humidity change and it is easy to maintain an optical characteristic.

  If the average film thickness of at least one of the high substitution degree layers is 0.2% or more and less than 25% of the low substitution degree layer average film thickness, if it is 0.2% or more, the peelability is sufficient, Unevenness, film thickness non-uniformity or optical property non-uniformity is suppressed, and if it is less than 25%, the optical development of the core layer can be used effectively, and the laminated film can obtain sufficient optical properties. It is preferable from the viewpoint that can be achieved. The average film thickness of at least one of the high substitution degree layers is more preferably from 0.5 to 15%, particularly preferably from 1.0 to 10%, of the low substitution degree layer average film thickness. Moreover, it is more preferable that the average film thicknesses of the skin A layer and the skin B layer are both 0.2% or more and less than 25% of the core layer average film thickness.

  Further, the average film thickness of the low substitution degree layer is 30 to 100 μm, and the average film thickness of at least one of the high substitution degree layers is 0.2% or more and less than 25% of the average film thickness of the low substitution degree layer. Is preferable from the viewpoint of retardation wavelength dispersion. Furthermore, the average film thickness of the low substitution degree layer is 30 to 100 μm, and the average film thickness of both of the high substitution degree layers is 0.2% or more and less than 25% of the average thickness of the low substitution degree layer. Is more preferable.

Moreover, when it has the laminated structure of two or more layers, it is preferable that the film thickness of the said low substitution degree layer (preferably core layer) is 30-70 micrometers, It is more preferable that it is 30-60 micrometers, It is 30-50 micrometers. It is particularly preferred.
When it has a laminated structure of two or more layers, it is more preferable that the thickness of the high substitution degree layer (preferably the surface layer on both sides of the film) is 0.5 to 20 μm, and 0.5 to 10 μm. Particularly preferred is 0.5 to 3 μm.

  A laminated structure in which an inner layer (core layer) is the low substitution layer and a surface layer (skin B layer and skin A layer) is the high substitution layer is an example of a three-layer lamination structure. More preferably, the skin B layer and the skin A layer are thinner than the core layer. The preferable conditions for the film thickness of the surface layer are the same as in the case of a laminated structure of three or more layers.

(Film width)
The film composed of the low substitution layer or the film composed of the low substitution layer and the high substitution layer preferably has a film width of 700 to 3000 mm, more preferably 1000 to 2800 mm, and 1500 to Particularly preferred is 2500 mm.
The film preferably has a film width of 700 to 3000 mm and a ΔRe of 10 nm or less.

(Method for producing low-substituted cellulose acylate film)
An example of a method for producing the low substitution cellulose acylate film (meaning the film comprising the low substitution layer or the film comprising the low substitution layer and the high substitution layer) is the above formula (1). Cellulose acylate solution satisfying the above-described requirements, and optionally a non-phosphate ester-based compound, a cellulose acylate solution for a low substitution degree layer, and a cellulose for a high substitution degree layer including a cellulose acylate satisfying the above formula (2) The step of forming a cellulose acylate laminated film by sequentially casting or co-casting the acylate solution, and the film thus formed contained a residual solvent of 5% by mass or more based on the total mass of the film. And a step of stretching at a temperature of Tg-30 ° C. or higher in the state (where Tg represents the glass transition temperature of the cellulose acylate laminated film). .

  The cellulose acylate laminated film is preferably formed by a solvent cast method. About the manufacture example of the cellulose acylate film using a solvent cast method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,492,078, 2,492,977, 2,492,978, 2,607,704, 2,739,069 and 2,739,070, British Patent Nos. 640731 and 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, JP-A-60-203430, and JP-A-62-115035 can be referred to. The cellulose acylate film may be subjected to a stretching treatment. With respect to the stretching method and conditions, for example, refer to JP-A-62-115035, JP-A-4-152125, 4-284221, 4-298310, and 11-48271. can do.

  As a solution casting method, a method in which the prepared dope is uniformly extruded from a pressure die onto a metal support, and a method using a doctor blade in which the dope once cast on the metal support is adjusted with a blade is used. Although there is a method using a reverse roll coater that adjusts with a reverse rotating roll, a method using a pressure die is preferred. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods mentioned here, it can be carried out by various known methods for casting a cellulose triacetate solution, and each condition is set in consideration of differences in the boiling point of the solvent used. Thus, the same effects as those described in the respective publications can be obtained.

  The low-substituted cellulose acylate film comprises a cellulose acylate satisfying the formula (1) and, optionally, a non-phosphate ester-based compound, a cellulose acylate solution for a low-substituted layer (casting dope). And a step of casting a cellulose acylate solution for a high substitution degree layer containing cellulose acylate satisfying the formula (2) onto a support to form a film, and the obtained film is stretched under predetermined conditions. Manufactured in a process including steps.

  In the production method, the viscosity of the cellulose acylate solution for the low substitution layer at 25 ° C. is 10% or more higher than the viscosity at 25 ° C. of the cellulose acylate solution for the high substitution layer. From the viewpoint of the distribution in the width direction and the suitability for producing a laminated film.

In the formation of the low-substituted cellulose acylate film, it is preferable to use a laminating casting method such as a co-casting method, a sequential casting method, and a coating method, and the simultaneous co-casting method is particularly preferable. It is particularly preferable from the viewpoint of manufacturing and production cost reduction.
When manufacturing by the co-casting method and the sequential casting method, first, a cellulose acetate solution (dope) for each layer is prepared. In the co-casting method (multi-layer simultaneous casting), a casting dope for each layer (which may be three layers or more) is simultaneously pressed from a separate slit or the like on a casting support (band or drum). This is a casting method in which the dope is extruded from the casting gies to be cast, and each layer is cast at the same time, peeled off from the support at an appropriate time, and dried to form a film. FIG. 2 is a cross-sectional view showing a state in which the co-casting giesser 3 is used to simultaneously extrude and cast the surface layer dope 1 and the core layer dope 2 on the casting support 4.

  In the sequential casting method, the casting dope for the first layer is first extruded from the casting giusa on the casting support, cast, and dried on the second layer without drying or drying. Extrude the casting dope for casting from the casting gieser, cast the dope sequentially to the third layer or more, if necessary, peel it off from the support at an appropriate time, and dry it. This is a casting method for forming a film. In general, the core layer film is formed into a film by a solution casting method to prepare a coating solution to be applied to the surface layer, and then applied to the film one side at a time or both sides simultaneously using an appropriate applicator. This is a method of forming a film having a laminated structure by applying and drying a liquid.

  The endlessly running metal support used to produce the low-substituted cellulose acylate film includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt (band) which is mirror-finished by surface polishing. May be used). One or more pressure dies may be installed above the metal support. Preferably 1 or 2 groups. When two or more are installed, the amount of dope to be cast may be divided into various ratios for each die, or the dope may be fed to the dies from each of a plurality of precision quantitative gear pumps. The temperature of the cellulose acylate solution used for casting is preferably −10 to 55 ° C., more preferably 25 to 50 ° C. In that case, all solution temperatures in the process may be the same or different at different points in the process. If they are different, the temperature may be a desired temperature just before casting.

  In the said manufacturing method, the process of extending | stretching the formed film at the temperature of Tg-30 degreeC or more in the state containing 5 mass% or more of residual solvents with respect to the mass of the whole film is included. For example, the wavelength dispersion characteristics of the film can impart such optical performance by stretching treatment, and can further impart a desired retardation to the cellulose acylate film. The stretching direction of the cellulose acylate film is preferably either the film conveyance direction or the direction (width direction) perpendicular to the conveyance direction, but the direction that is perpendicular to the film conveyance direction (width direction) is used for the subsequent film. This is particularly preferable from the viewpoint of the polarizing plate processing process.

  Methods for stretching in the width direction are described in, for example, JP-A-62-115035, JP-A-4-152125, JP-A-2842211, JP-A-298310, and JP-A-11-48271. Yes. In the case of stretching in the longitudinal direction, for example, the film is stretched by adjusting the speed of the film transport roller so that the film winding speed is higher than the film peeling speed. In the case of stretching in the width direction, the film can also be stretched by conveying while holding the width of the film with a tenter and gradually widening the width of the tenter. After the film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).

  The draw ratio of the low-substituted cellulose acylate film is preferably 5% to 200%, more preferably 5% to 100%, and particularly preferably 5% to 50%.

  When the low-substituted cellulose acylate film is used as a protective film for a polarizer, the transmission axis of the polarizer and the low-substituted cellulose acylate are controlled in order to suppress light leakage when the polarizing plate is viewed obliquely. It is necessary to arrange the slow axis in the plane of the rate film parallel or orthogonal. Since the transmission axis of the roll film-like polarizer produced continuously is generally parallel to the width direction of the roll film, the roll film-like polarizer and the roll film-like low substitution cellulose cellulose In order to continuously bond a protective film made of a rate film, the in-plane slow axis of the roll film-like protective film needs to be parallel or perpendicular to the width direction of the film. Therefore, it is preferable to stretch more in the width direction. In addition, the stretching treatment may be performed in the middle of the film forming process, or the raw film that has been formed and wound may be stretched. However, in the manufacturing method, the stretching is performed in a state containing a residual solvent. It is preferable to stretch in the middle of the film forming process.

  From the viewpoint of retardation development, it includes a step of drying the cellulose acylate laminated film after the stretching step and a step of stretching the dried cellulose acylate laminated film at a temperature of Tg-10 ° C or higher. preferable.

  The dope drying on the metal support involved in the production of the low-substituted cellulose acylate film is generally performed on the surface side of the metal support (drum or belt), that is, on the web on the metal support. A method of applying hot air from the front surface, a method of applying hot air from the back surface of the drum or belt, contacting a temperature-controlled liquid from the back surface opposite to the belt or drum dope casting surface, and heating the drum or belt by heat transfer However, there is a back surface liquid heat transfer method for controlling the surface temperature, and the back surface liquid heat transfer method is preferable. The surface temperature of the metal support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the metal support, the temperature should be set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent. Is preferred. This is not the case when the cast dope is cooled and peeled off without drying.

  The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like so as to obtain a desired thickness.

  The length of the low-substituted cellulose acylate film obtained as described above is preferably wound at 100 to 10,000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 10,000 m. 6000 m. When winding, it is preferable to give knurling to at least one end, the knurling width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. is there. This may be a single push or a double push.

Optically anisotropic layer:
The optical compensation film of the present invention has an optically anisotropic layer made of a composition containing a polymerizable liquid crystal compound. The liquid crystal compound used for forming the optically anisotropic layer may be a rod-like liquid crystal or a disk-like liquid crystal. From the viewpoint of improving viewing angle characteristics, a disc-shaped liquid crystal is preferable. Examples of the discotic liquid crystal include a triphenylene compound and a trisubstituted benzene compound. Among these, trisubstituted benzene compounds are preferable, and examples of the compounds include compounds of the general formula (DI) described in [0033] to [0098] of JP-A-2009-98645 and specific examples thereof.
In addition, the description of the said gazette can be referred also about the additive and formation method which can be utilized for formation of the said optically anisotropic layer.

  In the optically anisotropic layer, the molecules of the liquid crystal compound are fixed in a hybrid alignment state. Hybrid orientation refers to the angle between the molecular long axis and the layer surface in a rod-like liquid crystal, and the angle between the disk surface and the layer surface in a disc-like liquid crystal (hereinafter referred to as “tilt angle”) in the layer thickness direction ( The orientation state is increasing or decreasing. Since the optically anisotropic layer is generally formed by orienting a composition containing a discotic liquid crystal compound on the surface of the alignment film, the layer has an alignment film interface and an air interface. To do. In hybrid alignment, the tilt angle is large on the alignment film interface side and small on the air interface side (that is, the tilt angle is decreased from the alignment film interface toward the air interface, hereinafter, “ `` Reverse hybrid orientation ''), and the aspect in which the tilt angle is small on the alignment film interface side and large on the air interface side (that is, the tilt angle increases from the alignment film interface toward the air interface, There are two modes (hereinafter referred to as “positive hybrid orientation”). Any aspect may be used from the viewpoint of viewing angle contrast, but the reverse hybrid orientation is more preferable from the viewpoint of front contrast.

  For the formation of the optically anisotropic layer, an alignment film may be used. As the alignment film, a film obtained by rubbing the surface of a film mainly composed of polyvinyl alcohol or modified polyvinyl alcohol may be used. it can. As described above, in the present invention, since the low-substitution layer having high hydrophilicity is used as a support for the optically anisotropic layer, the coating property is good and hydrophilic polyvinyl alcohol or modified polyvinyl alcohol is used. Can be formed with high surface uniformity. As a result, high surface uniformity can be achieved also for the optically anisotropic layer formed thereon.

  An example of a composition capable of achieving the reverse hybrid alignment state is at least one pyridinium compound represented by the following general formula (II) (more preferably, general formula (II ′)) together with the 3-substituted benzene. And at least one compound containing a triazine ring group represented by the following general formula (III). The addition amount of the pyridinium compound is preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the discotic liquid crystal compound. Moreover, it is preferable that the addition amount of the compound containing the said triazine ring group is 0.2-0.4 mass part with respect to 100 mass parts of discotic liquid crystal compounds.

Wherein L ²³ and L ²⁴ are each a divalent linking group; R ²² is a hydrogen atom, an unsubstituted amino group, or a substituted amino group having 1 to 20 carbon atoms; X is an anion; Y ²² and Y ²³ are each a divalent linking group having a 5- or 6-membered ring which may be substituted as a partial structure; Z ²¹ is halogen-substituted phenyl, nitro-substituted phenyl, cyano-substituted phenyl, or the number of carbon atoms Is phenyl substituted with an alkyl group having 1 to 10 carbon atoms, phenyl substituted with an alkoxy group having 2 to 10 carbon atoms, an alkyl group having 1 to 12 carbon atoms, an alkynyl group having 2 to 20 carbon atoms , An alkoxy group having 1 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 13 carbon atoms, an aryloxycarbonyl group having 7 to 26 carbon atoms, and an aryl carbon having 7 to 26 carbon atoms A monovalent radical selected from the group consisting of oxy group; p is a number from 1 to 10; and m is 1 or 2.

In the formula, R ³¹ , R ³² and R ³³ represent an alkyl group or an alkoxy group having a CF ₃ group at the end, provided that two or more not adjacent in the alkyl group (including the alkyl group in the alkoxy group) May be substituted with an oxygen atom or a sulfur atom; X ³¹ , X ³² and X ³³ are each an alkylene group, —CO—, —NH—, —O—, —S—, —SO _2. -Represents a group obtained by combining at least two divalent linking groups selected from the group; and m31, m32 and m33 each represent a number of 1 to 5. In the above formula (III), each of R ³¹ , R ³² and R ³³ is preferably a group represented by the following formula.
_{-O (C n H 2n) n1} O (C m H 2m) m1 -C k F 2k + 1
In the formula, n and m are each 1 to 3, n1 and m1 are each 1 to 3, and k is 1 to 10.

式（II’）中、式(II)と同一の符号は同一の意義であり；Ｌ²⁵はＬ²⁴と同義であり；Ｒ²³、Ｒ²⁴及びＲ²⁵はそれぞれ、炭素原子数が１〜１２のアルキル基を表し、ｎ２３は０〜４、ｎ２４は１〜４、及びｎ２５は０〜４を表す。
る。

In the formula (II ′), the same symbols as those in the formula (II) have the same meaning; L ²⁵ has the same meaning as L ²⁴ ; R ²³ , R ²⁴ and R ²⁵ each have 1 to 12 carbon atoms. N23 represents 0 to 4, n24 represents 1 to 4, and n25 represents 0 to 4.
The

An optical compensation film containing a discotic liquid crystal fixed in a hybrid alignment state preferably exhibits the following optical characteristics.
The retardation R [0 °] with respect to incident light with a wavelength of 550 nm, measured from the normal direction of the optical compensation film, is expressed by the following relational expression: 10 nm ≦ R [0 °] ≦ 200 nm
And measured in a direction that is perpendicular to the in-plane slow axis of the optical compensation film and that is inclined by + 40 ° from the normal to the surface direction of the retardation layer in the plane including the normal (incident surface). Retardation R [+ 40 °] and retardation R [-40 °] measured from a direction inclined by 40 ° with respect to the normal line are represented by the following formulas (I) and (I ′):
When R [+ 40 °]> R [−40 °] 1.1 ≦ R [+ 40 °] / R [−40 °] ≦ 10 (I)
When R [+ 40 °] <R [−40 °] 1.1 ≦ R [−40 °] / R [+ 40 °] ≦ 10 (I ′)
It is preferable to satisfy

First and second polarizers:
In the present invention, the first and second polarizers are not particularly limited. A commonly used linear polarizing film can be used. The linear polarizing film is manufactured by Optiva Inc. And a polarizing film comprising a binder and iodine or a dichroic dye is preferable. The iodine and the dichroic dye in the linearly polarizing film exhibit polarizing performance by being oriented in the binder. It is preferable that the iodine and the dichroic dye are aligned along the binder molecule, or the dichroic dye is aligned in one direction by self-assembly such as liquid crystal. Currently, commercially available polarizers are made by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing iodine or dichroic dye to penetrate into the binder. Is common.

Outside protective film:
The liquid crystal display device of the present invention preferably has an outer protective film disposed on the outer side of the first and second polarizers. There is no restriction | limiting in particular about an outer side protective film. Films of cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene, polyester and the like can be used. A cellulose acylate film is preferred, and a cellulose acetate film is more preferred. A commercially available cellulose acetate film (for example, “TD80U” manufactured by Fuji Film Co., Ltd.) can also be used.

At least one of the two outer protective films is preferably made of the low-substituted cellulose acylate film from the viewpoint of reducing frame-shaped light leakage.
On the other hand, at least one (more preferably both) of the two outer protective films is selected from a cyclic olefin resin, a polyolefin resin, a polyester resin, a polycarbonate resin, an acrylate resin, and a cellulose acylate resin. A film containing at least one kind is preferable from the viewpoint of durability against humidity.

LCD cell:
There is no particular limitation on the mode of the liquid crystal display device of the present invention. The effect can be obtained in any of the twisted alignment modes such as the TN mode and the STN mode, and the OCB mode and ECB mode liquid crystal display devices of the non-twisted alignment mode. Among them, the twist orientation mode is preferable, and the TN mode is preferable.
There is no particular limitation on the TN mode liquid crystal cell. Various conventionally known configurations can be employed. A TN mode liquid crystal cell generally has a liquid crystal layer made of a nematic liquid crystal material, and the liquid crystal layer is in a twisted alignment state when no driving voltage is applied, and in a vertical alignment state with respect to the substrate surface when a driving voltage is applied. It is configured as follows. Since the upper and lower polarizers are arranged with their transmission axes orthogonal to each other, the linearly polarized light incident on the liquid crystal cell from the backlight placed behind the lower polarizer is not twisted in the liquid crystal layer when no drive voltage is applied. It rotates 90 ° along the orientation, passes through the transmission axis of the upper polarizer, and displays white. On the other hand, when the drive voltage is applied, the linearly polarized light incident on the liquid crystal cell passes through while maintaining the polarization state, and is thus shielded by the upper polarizer, resulting in black display. The liquid crystal layer of the TN mode liquid crystal cell usually has a product Δn · d of a thickness d (micron) and a refractive index anisotropy Δn of about 0.1 to 1.5 μm.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

1. Preparation example of cellulose acylate film (Preparation of cellulose acylate)
Cellulose acylate was synthesized by the method described in JP-A-10-45804 and 08-231761, and the degree of substitution was measured. Specifically, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. In addition, aging was performed at 40 ° C. after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.

(Preparation of cellulose acylate solutions “C01” to “C13”)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution. The amount of the solvent (methylene chloride and methanol) was appropriately adjusted so that the solid content concentration of each cellulose acylate solution was 22% by mass and the viscosity was 60 Pa · s.
―――――――――――――――――――――――――――――――――――――
-Cellulose acetate (the degree of substitution is shown in the following table) 100.0 parts by mass-Additives listed in the following table Amounts listed in the following table-Methylene chloride 365.5 parts by mass-Methanol 54.6 parts by mass ―――――――――――――――――――――――――――――――――
As shown in the table below, the cellulose acylate solution for other low-substituted layers is the same as “C01” except that the acyl group type and substitution degree of cellulose acylate, the amount of additive and additive type are changed. Was prepared. The amount of the solvent (methylene chloride and methanol) was appropriately adjusted so that the solid content concentration of each cellulose acylate solution was 22% by mass. However, for C06, the amount of the solvent was appropriately adjusted so that the solid content concentration was 19% by mass.

(Production of cellulose acylate film)
Using one or more cellulose acylate solutions, a film was produced by either the following single casting or co-casting. The stretching temperature and the stretching ratio are shown in the following table.
Single casting:
One of the cellulose acylate solutions in the above table was cast using a band stretching machine so as to have a film thickness of 60 μm. Subsequently, the obtained web (film) was peeled from the band, sandwiched between clips, and transversely stretched using a tenter. The stretching temperature and the stretching ratio are shown in the following table. Thereafter, the clip was removed from the film and dried at 130 ° C. for 20 minutes to obtain a film.
Co-casting:
Each of the cellulose acylate solutions C01 and C10 is a band stretching machine so that the cellulose acylate solutions C11 and C12 become a skin A layer having a thickness of 2 μm so that the cellulose acylate solutions C11 and C12 become a core layer having a thickness of 56 μm. Was used for casting. Subsequently, the obtained web (film) was peeled from the band, sandwiched between clips, and transversely stretched using a tenter. The stretching temperature and the stretching ratio are shown in the following table. Thereafter, the clip was removed from the film and dried at 130 ° C. for 20 minutes to obtain a film.
The following table shows the composition of the obtained film, stretching conditions, and film characteristics.

  In the above table, Re represents an absolute value. The sign of Re is determined by the film arrangement (mainly the relationship with the transmission axis of the polarizing film) when incorporated in a liquid crystal display.

Since the film 2 has a small film thickness, the handling property at the time of producing a web-like film is poor, which is not preferable from the viewpoint of production stability. Further, since the film 2 was thin, the film surface was deteriorated such as wrinkles.
Films 10 and 11 provided with a skin A layer of cellulose acylate having a high degree of substitution on the band surface have a smaller load when peeled from the band than other films, and are easy to peel off from the band. Yes, from the viewpoint of manufacturing stability.

2. Production of Optical Compensation Film An optically anisotropic film was produced by forming an optically anisotropic layer on the surface of each film produced as described above by any of the following methods. In film 3, an optically anisotropic layer was formed on the surface of the low substitution degree layer.
(1) Production of optical compensation film having optically anisotropic layers α1 to α3 (formation of alignment film)
The surface of each film was saponified, and an alignment film coating solution having the following composition was continuously applied to the saponified surface with a # 16 wire bar. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 90 ° C. for 150 seconds. The formed film surface was rubbed with a rubbing roll in a direction parallel to the conveying direction at 500 rpm to produce an alignment film.
(Composition of alignment film coating solution)
――――――――――――――――――――――――――
The following modified polyvinyl alcohol 20 parts by mass Water 360 parts by mass Methanol 120 parts by mass Glutaraldehyde (cross-linking agent) 1 part by mass ――――――――――――――――――――――――― -

(Formation of optically anisotropic layer α1)
The following coating solution was continuously applied to the alignment film surface of the film using a # 3.2 wire bar. In the step of continuously heating from room temperature to 100 ° C., the solvent is dried, and then the film surface wind speed corresponding to the discotic liquid crystal compound layer is 1.5 m / sec in parallel with the film conveyance direction in the 135 ° C. drying zone. And heated for about 90 seconds to align the discotic liquid crystal compound. 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 carried out for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystal compound was fixed to the orientation. Then, it stood to cool to room temperature, the optically anisotropic layer was formed on the surface of each film, and the optical compensation film was produced.
(Optical anisotropic layer coating composition)
―――――――――――――――――――――――――――――――――――――
Methyl ethyl ketone 98 parts by mass The following discotic liquid crystalline compound (1) 41.01 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, 4.06 parts by mass, Osaka Organic Chemical Co., Ltd.) Cellulose acetate butyrate (CAB551) -0.2, manufactured by Eastman Chemical Co.) 0.34 parts by mass Cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co.) 0.11 parts by mass The following fluoroaliphatic group-containing polymer 1 0.13 parts by mass Fluoroaliphatic group-containing polymer 2 0.03 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 1.35 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.45 parts by mass ―――――――――――――――――――――――――― ----------

(Formation of optically anisotropic layer α2)
An alignment film was formed on the film 13 in the same manner as described above, and an optically anisotropic layer α2 was formed on the alignment film to produce an optical compensation film. The optically anisotropic layer α2 is composed of 107 parts by mass of methyl ethyl ketone in the composition of the optically anisotropic layer coating composition used for forming the optically anisotropic layer α1, and the fluoroaliphatic group-containing polymer 2 described above. An optical compensation film was prepared using the optically anisotropic layer coating composition having the same composition except that was changed to 0.09 parts by mass in the same manner as the optically anisotropic layer α1.

(Formation of optically anisotropic layer α3)
An alignment film was formed on the film 14 in the same manner as described above, and an optically anisotropic layer α3 was formed on the alignment film to prepare an optical compensation film. The optically anisotropic layer α3 is composed of 107 parts by mass of methyl ethyl ketone in the composition of the optically anisotropic layer coating composition used for forming the optically anisotropic layer α1, and the fluoroaliphatic group-containing polymer 2 described above. An optical compensation film was prepared using the optically anisotropic layer coating composition having the same composition except that the content was changed to 0 parts by mass in the same manner as the optically anisotropic layer α1.

(2) Production of optical compensation film having any of optically anisotropic layers β1 to β3 (formation of alignment film)
An alignment film was formed on the surface of each film in the same manner as described above.
(Formation of optically anisotropic layers β1 to β3)
Next, an optically anisotropic layer coating solution having the following composition was continuously applied to the surface of the alignment film using a # 1.6 wire bar. In the process of continuously heating from room temperature to 100 ° C., the solvent was dried, and then heated in a drying zone at 115 ° C. for about 90 seconds to align the discotic liquid crystal compound. Next, it is transported to a drying zone at 80 ° C., and irradiated with ultraviolet rays having an illuminance of 600 mW for 4 seconds by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, light emission length 1.6 m) to advance the crosslinking reaction, The tick liquid crystal compound was fixed in its orientation. Then, it stood to cool to room temperature, formed any one of optical anisotropic layers (beta) 1-beta3, and produced the optical compensation film.
The optically anisotropic layers β1 to β3 are formed by using compositions containing the following discotic liquid crystalline compounds β1 to β3, respectively, as the discotic liquid crystalline compounds in the following compositions. It is.
(Optical anisotropic layer coating composition)
―――――――――――――――――――――――――――――――――――――
Methyl ethyl ketone 217 parts by mass Any one of the following discotic liquid crystal compounds β1 to β3 90 parts by mass The above discotic liquid crystal compound 1 10 parts by mass The air interface alignment controller shown below 1 part by mass photopolymerization initiator (Irgacure 907, Ciba Geigy 3 parts by mass sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass ――――――――――――――――――――――――― ―――――――――――

  As described above, optically anisotropic layers β1 to β3 were formed, and optical compensation films were prepared.

(3) Production of optical compensation film having optically anisotropic layer γ1 or γ2 (production of alignment film)
In the same manner as described above, an alignment film was formed on the surface of the film.
(Formation of optically anisotropic layer γ1)
A coating solution having the following composition was prepared.
────────────────────────────────────
Methyl ethyl ketone 61.0 parts by mass The following discotic liquid crystalline compound γ1 30.0 parts by mass The following fluoroaliphatic group-containing polymer 3 0.9 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 0.3 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.3 parts by mass ────────────────────────────── ──────

  The coating solution was continuously applied to the alignment film surface using a # 2.0 wire bar. In the process of continuously heating from room temperature to 100 ° C., the solvent is dried, and then, in the 125 ° C. drying zone, the film surface wind speed corresponding to the coating film is 1.5 m / sec parallel to the film transport direction. For about 90 seconds to align the discotic liquid crystal compound. 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 carried out for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystal compound was fixed to the orientation. Then, it stood to cool to room temperature, the optically anisotropic layer was formed, and the optical compensation film was produced.

  The optically anisotropic layer γ1 was formed as described above. The discotic liquid crystal molecules in the optically anisotropic layer γ1 were fixed in a positive hybrid state in which the tilt angle increased from the alignment film interface toward the air interface.

(Formation of optically anisotropic layer γ2)
In the method for forming the optically anisotropic layer γ1, the alignment film forming composition is changed to the following composition, and the additive added to the optically anisotropic layer forming coating liquid is changed to the following additive. An optically anisotropic layer γ2 was formed in the same manner as the optically anisotropic layer γ1 except that.
(Formation of alignment film)
The surface of each film was saponified, and a coating solution for forming an alignment film having the following composition was applied to the saponified surface with a # 14 wire bar coater at 24 ml / m ² and dried with hot air at 100 ° C. for 120 seconds. Next, the longitudinal direction (conveying direction) of the film was set to 0 °, and a rubbing treatment having a width of 2000 mm was used for the formed alignment film, and the rubbing treatment was performed in the 0 ° direction at a rotation speed of the rubbing roller of 400 rpm. At this time, the conveyance speed was 40 m / min. Subsequently, the rubbing surface was subjected to ultrasonic dust removal.
―――――――――――――――――――――――――――――――――――――
Composition of coating solution for alignment film formation ―――――――――――――――――――――――――――――――――――――
-Alignment film polymer 40 parts by weight-Water 700 parts by weight-Methanol 300 parts by weight-Triethylamine 20 parts by weight-------------- ―――――――――――

(Formation of optically anisotropic layer)
A coating liquid for optically anisotropic layer having the composition shown in the following table was applied to the rubbing-treated surface of the alignment film after dust removal using a wire bar. Then, it heated for 120 second in a 130 degreeC thermostat, and the discotic liquid crystal compound was orientated. Next, using a 160 W / cm high-pressure mercury lamp at 80 ° C., UV irradiation was performed for 40 seconds to advance the crosslinking reaction, thereby polymerizing the discotic liquid crystal compound. Then, it stood to cool to room temperature.

――――――――――――――――――――――――――――――――――――――
Composition of coating solution for optically anisotropic layer formation ――――――――――――――――――――――――――――――――――――――
-270 parts by mass of methyl ethyl ketone-100 parts by mass of the following discotic liquid crystalline compound γ2-1.0 part by mass of the air interface alignment controller of B1 below-photoinitiator Irgacure 907 3.0 parts by mass of Ciba Japan Co., Ltd. Sensitizer KayaCure DETX Nippon Kayaku 1.0 parts by mass ―――――――――――――――――――――――――――――――――――― -

  The discotic liquid crystal molecules in the optically anisotropic layer γ2 were fixed in an inverted hybrid state in which the tilt angle decreased from the alignment film interface toward the air interface.

(Measurement of optical properties)
About each produced optical compensation film, in-plane retardation Re (550) of wavelength 550nm was measured using KOBRA-WR (made by Oji Scientific Instruments). In addition, in the plane perpendicular to the slow axis of each optical compensation film, light having a wavelength of 550 nm is incident from a direction inclined by ± 40 degrees from the normal direction to cause retardation R [+ 40 °] and R [−40 °]. ] Was measured, and R [+ 40 °] / R [−40 °] was calculated.
The results are shown in the table below.

(Surface evaluation of optical compensation film)
Each of the optical compensation films prepared above was inserted between a pair of polarizers having absorption axes orthogonal to each other, placed on a surface light source, and visually observed in a dark room to perform surface evaluation.
○: The surface shape was improved with respect to the optical compensation film (of Comparative Example 1).
X: It was the same surface shape as the optical compensation film (of Comparative Example 1).

3. Preparation of Polarizing Plate A polarizing plate was prepared by combining any two optical compensation films prepared above and bonding them to the surface of the linearly polarizing film. In addition, the alkali saponification process was given to the bonding surface of each film. The linearly polarizing film is a 20 μm thick linearly polarizing film produced by continuously stretching a polyvinyl alcohol film having a thickness of 80 μm in an iodine aqueous solution 5 times and drying, and as an adhesive, A 3% aqueous solution of polyvinyl alcohol (PVA-117H manufactured by Kuraray) was used. Moreover, the surface of the low substitution degree layer was bonded to the surface of the polarizing film, and the surface of the high substitution degree layer was bonded to the surface of the polarizing film for the film that is a laminate with the high substitution degree layer.

4). Production of liquid crystal display and evaluation results (1) Production of TN mode liquid crystal display A liquid crystal display using a TN type liquid crystal cell (V2200eco, a pair of polarizing plates provided by BenQ Japan Co., Ltd. was peeled off and replaced Two sheets of the above-prepared polarizing plate were selected and attached to the viewer side and the backlight side one by one through the adhesive, and at this time, the transmission axis of the polarizing plate on the viewer side, The transmission axis of the polarizing plate on the backlight side was arranged to be orthogonal.
Each TN mode liquid crystal display device having the configuration shown in the following table was produced.

(2) Evaluation of liquid crystal display devices (evaluation of frame-shaped light leakage)
Each liquid crystal display device prepared above was dried at 70 ° C. and placed in a drier for 170 hours and then taken out. The entire liquid crystal display device was in a black display state and visually observed in a dark room to evaluate light leakage.
A: No light leakage was observed around the polarizing plate (no problem in practical use).
○: Little light leakage was observed around the polarizing plate (no problem in practical use).
Δ: Light leakage was observed around the polarizing plate, but there was no practical problem.
X: Light leakage is observed around the polarizing plate, which is problematic in practice.

(Evaluation of front CR)
About each liquid crystal display device, the brightness | luminance of a front direction (normal direction with respect to a display surface) is measured by black display and white display using measuring machine "EZ-Contrast XL88" (made by ELDIM), and contrast ratio ( (White luminance / black luminance) was calculated and evaluated according to the following criteria.
◎: Front CR is 1200 or more ○: Front CR is 900 or more and less than 1200 △: Front CR is 800 or more and less than 900 ×: Front CR is less than 800

(CR viewing angle evaluation)
About each liquid crystal display device, the viewing angle was measured by black display and white display using measuring machine "EZ-Contrast XL88" (made by ELDIM). A region having a contrast ratio (white luminance / black luminance) of 10 or more was obtained as a viewing angle in the vertical and horizontal directions. Evaluation was made according to the following criteria. The results are shown in the table below.
When the total of the upper, lower, left, and right viewing angles for achieving a contrast of 10 or more is 320 ° or more, the display characteristics are practically excellent.
<Evaluation>
○: Total of angles satisfying up / down / left / right CR ≧ 10 is 320 ° or more Δ: Total angle of up / down / left / right CR ≧ 10 exceeds 240 ° and less than 320 ° ×: Total of angles satisfying top / bottom / left / right CR ≧ 10 is 240 Below

(Evaluation of uniformity of display characteristics)
Each of the liquid crystal display devices prepared above was in a black display state on the entire surface, and was visually observed in a dark room for evaluation of the surface state.
A: The surface shape was improved with respect to the liquid crystal display device of Comparative Example 1.
X: The surface shape was the same as that of the liquid crystal display device of Comparative Example 1.

  A liquid crystal display device was produced in the same manner as in Example 1 except that the inner protective film (support) in Example 1 was changed from film 1 to films 7, 8 and 9, respectively. Display performance was evaluated. Further, a liquid crystal display device was produced and evaluated in the same manner as in Example 6 except that the inner protective film (support) in Example 6 was changed from the film 10 to the film 15. As a result, as shown in the following table, each of the liquid crystal display devices manufactured using the films 6, 7, 8 and 15 also has a frame-like light leakage reduced in the same manner as in Example 1 or Example 6, and The uniformity of display characteristics and display characteristics have been improved. The following table also shows the results of Example 1 and Example 6.

In Tables 3 to 5 above,
The sign of Re of the support (film) is positive: the slow axis of the film is orthogonal to the absorption axis of the adjacent polarizer;
The sign of Re of the support (film) is negative: the slow axis of the film is parallel to the absorption axis of the adjacent polarizer;
Means that it was placed in
The optically anisotropic layer made of the liquid crystal composition was disposed so that the rubbing direction and the absorption axis of the polarizer were parallel.

5). Examples 20-24
The surface of a commercially available norbornene-based polymer film “ZEONOR ZF14-060” (manufactured by Optes Co., Ltd.) was subjected to corona discharge treatment using a solid state corona treatment machine 6KVA (manufactured by Pillar Co., Ltd.). This film was used as film 16. The thickness of this film was 60 μm. Moreover, the film 16 was Re (550) = 2nm and Rth (550) = 3nm.

  The surface of a commercially available cycloolefin polymer film “ARTON FLZR50” (manufactured by JSR Corporation) was subjected to corona discharge treatment in the same manner as for the film 16. This film was used as film 17. The thickness of this film was 50 μm. The film 17 had Re (550) = 2 nm and Rth (550) = 2 nm.

  A stretched film (protective film A) was produced according to the description of [0223] to [0226] of JP-A No. 2007-127893. An easy-adhesion layer coating composition P-2 is prepared on the surface of the protective film A according to the description in [0232] of the same publication, and the composition is stretched according to the method described in [0246] of the publication. An easy-adhesion layer was formed by coating on the surface of the film. This film was used as film 18. The thickness of this film was 31 μm. In addition, the film 18 had Re (550) = 1 nm and Rth (550) = 1 nm.

  A propylene / ethylene random copolymer (Sumitomo Nobrene W151, manufactured by Sumitomo Chemical Co., Ltd.) containing about 5% by mass of an ethylene unit is 260 ° C. in a melt extrusion machine in which a T-die is arranged in a single-screw melt extruder. Extrusion was performed at the melting temperature of to obtain a raw film. Thereafter, both the front and back surfaces of the raw film were subjected to corona discharge treatment. This film was used as film 19. The thickness of this film was 81 μm. Moreover, the film 19 was Re (550) = 7 nm and Rth (550) = 28 nm.

  Polyethylene terephthalate (PET) synthesized by a conventional method was made into a chip shape, dried in a Henschel mixer and a paddle dryer dryer to a water content of 50 ppm or less, and then melted in an extruder set at a heater temperature of 280 to 300 degrees. The melted polyester resin was discharged onto a chiller roll electrostatically applied from the die part to obtain an amorphous base. The amorphous base was stretched in the base flow direction at a stretch ratio of 3.3 times, and then stretched in the width direction at a stretch ratio of 3.9 times. This film was used as the film 20. The thickness of this film was 78 μm. Moreover, the film 20 was Re (550) = 1400 nm and Rth (550) = 7000 nm.

  In the same manner as in Example 1 except that the outer protective film (viewing side) and (BL side) in Example 1 were changed from film 6 to films 16, 17, 18, 19 and 20, respectively, a liquid crystal display device ( Examples 20 to 24) were prepared, and display performance evaluation similar to that of Example 1 was performed. As a result, each of the liquid crystal display devices of Examples 20 to 24 manufactured using the films 16, 17, 18, 19, and 20 also has a reduced frame-like light leakage as in Example 1, and display characteristics. It was confirmed that the uniformity and display characteristics of the display were improved.

(Evaluation of light leakage under high humidity conditions)
Each of the liquid crystal display devices of Examples 20 to 24 produced using Example 1 and Films 16 to 20 above were placed in a constant temperature and humidity chamber at 60 ° C. and 90% for 100 hours, and then taken out, and then the entire surface was black. The display state was observed visually in a dark room, and light leakage was evaluated according to the following criteria.
A: Little light leakage was observed (no problem in practical use).
○: Light leakage was observed, but there is no practical problem.
The liquid crystal display device of Example 1 was evaluated as “◯”, whereas the evaluation of the liquid crystal display devices of Examples 20 to 24 was “◎” and had excellent durability against humidity. all right.

It can be understood that the liquid crystal display devices according to the embodiments of the present invention all have reduced frame-like light leakage. This effect is that the liquid crystal display device according to the example has a film (having a thickness of about 60 μm) made of or including a low substitution layer as a protective film inside and / or outside the polarizer. Therefore, it can be considered that the thickness of the optical compensation film is about 20 μm, which is thinner than the liquid crystal display device of the comparative example, and as a result, the distortion of the liquid crystal panel and the polarizing plate due to heat or the like can be reduced.
Furthermore, all of the liquid crystal display devices of the embodiments of the present invention have uniform display characteristics. For this reason, an alignment film and an optically anisotropic layer are formed on the low substitution degree layer, so that the high substitution degree layer is formed. This is considered to be because the smoothness of the surface of the optically anisotropic layer is higher than that of the comparative example in which the alignment film and the optically anisotropic layer are formed.

11, 12 Polarizer 13 TN mode liquid crystal cell 14, 16 Inner protective film (support; low substitution degree layer)
15, 17 Optically anisotropic layers 18, 19 Outer protective films 20, 21 Optical compensation films 22, 23 Polarizing plate

Claims (18)

An optical compensation film comprising a low-substitution layer containing, as a main component, cellulose acylate satisfying the following formula (1), and an optically anisotropic layer comprising a composition containing a polymerizable liquid crystal compound.
(1) 2.0 <Z1 <2.7
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the low substitution degree layer.) The low substitution layer has an in-plane retardation Re (550) at a wavelength of 550 nm of −50 to 200 nm, and a thickness direction retardation Rth (550) at a wavelength of 550 nm of 0 to 250 nm. The optical compensation film according to claim 1. The optical compensation film according to claim 1, wherein the polymerizable liquid crystal compound is a discotic liquid crystal compound. The optical compensation film according to claim 1, wherein the low substitution layer further contains a non-phosphate ester compound. 5. The high substitution layer containing, as a main component, cellulose acylate satisfying the following formula (2) is provided on at least one surface of the low substitution layer. Optical compensation film.
(2) 2.7 <Z2
(In formula (2), Z2 represents the total acyl substitution degree of the cellulose acylate of the high substitution degree layer.) The optical compensation film according to claim 5, wherein the low substitution degree layer and the high substitution degree layer are laminated by co-casting. The high substitution layer contains a non-phosphate ester compound as an additive, and the ratio (part by mass) of the additive to the cellulose acylate contained in the high substitution layer is contained in the low substitution layer The optical compensation film according to claim 5 or 6, wherein the amount is less than the ratio (parts by mass) of the additive to cellulose acylate. The optical compensation film according to any one of claims 4 to 7, wherein the non-phosphate ester compound is a polyester compound containing an aromatic ring. The optical compensation film according to any one of claims 1 to 8, wherein the cellulose acylate contained in the low substitution degree layer satisfies the following formulas (3) to (5).
Formula (3) 1.0 <X1 <2.7
Formula (4) 0 <= Y1 <1.5
Formula (5) X1 + Y1 = Z1
(In the formulas (3), (4) and (5), X1 represents the degree of substitution of the acetyl group of the cellulose acylate of the low-substituted layer, and Y1 has 3 or more carbon atoms of the cellulose acylate of the low-substituted layer. The total substitution degree of acyl groups is represented, and Z1 represents the total acyl substitution degree of cellulose acylate in the low substitution layer.) The optical compensation film according to any one of claims 5 to 9, wherein the cellulose acylate used in the high substitution degree layer satisfies the following formulas (6) to (8).
Formula (6) 1.2 <X2 <3.0
Formula (7) 0 <= Y2 <1.5
Formula (8) X2 + Y2 = Z2
(In the formulas (6), (7) and (8), X2 represents the substitution degree of the acetyl group of the cellulose acylate of the high substitution degree layer, and Y2 has 3 or more carbon atoms of the cellulose acylate of the high substitution degree layer. The total substitution degree of acyl groups is represented, and Z2 represents the total acyl substitution degree of cellulose acylate in the high substitution degree layer. The number of carbon atoms of the acyl group of the cellulose acylate contained in the low substitution degree layer and / or the high substitution degree layer is 2 to 4, according to any one of claims 1 to 10. Optical compensation film. The optical compensation film according to claim 1, wherein the cellulose acylate contained in the low substitution layer and / or the high substitution layer is cellulose acetate. The retardation Re (550) in the in-plane direction at a wavelength of 550 nm is 10 to 200 nm, and the retardation R at a wavelength of 550 nm in a direction inclined by ± 40 degrees from the normal direction in a plane orthogonal to the in-plane slow axis. [+ 40 °] and R [−40 °] are represented by the following formulas (I) and (I ′)
When R [+ 40 °]> R [−40 °] 1.1 ≦ R [+ 40 °] / R [−40 °] ≦ 10 (I)
When R [+ 40 °] <R [−40 °] 1.1 ≦ R [−40 °] / R [+ 40 °] ≦ 10 (I ′)
The optical compensation film according to claim 1, wherein: The polarizing plate which has a polarizer and the optical compensation film of any one of Claims 1-13 at least. A pair of polarizers arranged with their polarization axes orthogonal to each other, a liquid crystal cell arranged therebetween, and a pair of polarizers and the liquid crystal cell according to any one of claims 1 to 13 A liquid crystal display device comprising the optical compensation film described above. The liquid crystal display device according to claim 15, wherein the liquid crystal display device is a twisted alignment mode. 17. The liquid crystal display according to claim 15, further comprising a low-substitution layer containing, as a main component, cellulose acylate satisfying the following formula (1) on at least one outer surface of the pair of polarizers. apparatus.
(1) 2.0 <Z1 <2.7
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the low substitution degree layer.) A film comprising at least one selected from a cyclic olefin resin, a polyolefin resin, a polyester resin, a polycarbonate resin, an acrylate resin, and a cellulose acylate resin on at least one outer surface of a pair of polarizers. The liquid crystal display device according to claim 15, wherein the liquid crystal display device is provided.

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