JP4551775B2 - Optical film, polarizing plate, and liquid crystal display device - Google Patents

Description

  The present invention relates to a cellulose acylate film and an optical film useful for a liquid crystal display device, a laminated polarizing plate in which the optical film is laminated, and a liquid crystal display device using them.

Cellulose acylate films are excellent as optical materials for devices that handle polarized light such as liquid crystal display devices because of their high optical transparency and high optical isotropy. It has been used as a support for optical protective films that can improve (viewing angle compensation) the protective film and display viewed from an oblique direction.
A polarizing plate, which is one of the members for a liquid crystal display device, has a polarizer protective film bonded to at least one side of the polarizer. A general polarizer is obtained by dyeing a stretched polyvinyl alcohol (PVA) film with iodine or a dichroic dye.
In many cases, as a polarizer protective film, a cellulose acylate film, particularly a triacetyl cellulose film, which can be directly bonded to PVA is used. It is important that the polarizer protective film is excellent in optical isotropy, and the optical characteristics of the polarizer protective film greatly affect the characteristics of the polarizing plate.
In recent liquid crystal display devices, improvement in viewing angle characteristics is strongly demanded, and optical transparent films such as a protective film for a polarizer and a support for an optical compensation film are more optically isotropic. It is required to be sex. In order to be optically isotropic, it is important that the retardation value represented by the product of birefringence and thickness of the optical film is small. In particular, in order to improve display from an oblique direction, it is necessary to reduce not only the retardation (Re) in the front direction but also the retardation (Rth) in the film thickness direction. Specifically, when the optical properties of the optical transparent film are evaluated, the Re measured from the front of the film is small, and it is required that the Re does not change even if the angle is changed.

  So far, there has been a cellulose acylate film with a small Re on the front, but it was difficult to produce a cellulose acylate film with a small Re change with angle, that is, a small Rth. Therefore, an optical transparent film having a small angle change of Re using a polycarbonate film or a thermoplastic cycloolefin film instead of a cellulose acylate film has been proposed (for example, Patent Documents 1 and 2, ZEONOR ( Zeon Corporation), ARTON (JSR Corporation), etc.). However, when these optically transparent films are used as a protective film for a polarizer, there is a problem in bonding properties with PVA because the film is hydrophobic. There also remains a problem that the optical characteristics of the entire film surface are non-uniform.

  As a solution to this problem, it is strongly desired to improve the cellulose acylate film which is excellent in the bonding property to PVA by further reducing the optical anisotropy. Specifically, it is an optically isotropic optically transparent film in which Re on the front surface of the cellulose acylate film is substantially zero and the change in retardation angle is small, that is, Rth is also substantially zero.

  In the production of a cellulose acylate film, a compound called a plasticizer is generally added to improve the film forming performance. As types of plasticizers, phosphate triesters such as triphenyl phosphate and biphenyl diphenyl phosphate, phthalates, and the like are disclosed (for example, see Non-Patent Document 1). Among these plasticizers, those having the effect of reducing the optical anisotropy of the cellulose acylate film are known. For example, specific fatty acid esters are disclosed (for example, see Patent Document 3). ). However, the effect of reducing the optical anisotropy of cellulose acylate films using these conventionally known compounds is not sufficient.

  Also, recent liquid crystal display devices are required to improve display color. Therefore, an optical transparent film such as a protective film for a polarizer or a support for an optical compensation film not only reduces Re and Rth in the visible region of a wavelength of 400 to 800 nm, but also changes Re and Rth depending on the wavelength, that is, wavelength dispersion. It needs to be small.

  In addition, since the display quality of the liquid crystal display device is high and the display quality of the liquid crystal display device is also required to be unaffected by the environmental humidity used, the protective film also has no optical unevenness and optical performance. It is required not to depend on humidity.

  Conventionally, a phase difference plate is used in various liquid crystal display devices for the purpose of optical compensation. Examples of such a phase difference plate include an optical biaxial phase difference plate, and these are mainly various polymer film stretching methods such as inter-roll tension stretching method, inter-roll compression stretching method, tenter transverse uniaxial stretching method and the like. It can be produced by a method or the like (for example, see Patent Document 4), a method for imparting anisotropy by biaxial stretching, or the like (for example, see Patent Document 5). In addition to this, a retardation plate using both a uniaxially stretched polymer film having positive optical anisotropy and a biaxially stretched polymer film having negative optical anisotropy having a small in-plane retardation value, (Refer to patent document 6.) There is also a retardation plate to which negative uniaxiality is imparted by forming a soluble polyimide film on a substrate, for example, due to the property of polyimide instead of the stretching method as described above ( For example, see Patent Document 7.)

According to the above-described film stretching technique or the like, the stretched film to be formed can be imparted with optical characteristics of, for example, nx>ny> nz. Here, nx, ny, and nz respectively indicate the refractive indexes of the X-axis, Y-axis, and Z-axis in the film, and the X-axis is an axial direction that indicates the maximum refractive index in the film plane, and Y The axis is an axial direction perpendicular to the X axis in the plane, and the Z axis indicates a thickness direction perpendicular to the X axis and the Y axis. If the birefringent film having such optical characteristics is disposed between a liquid crystal cell of a liquid crystal display device and a polarizer, for example, the display characteristics of the liquid crystal display device can be widened. It is useful as a viewing angle compensation film.
JP 2001-318233 A JP 2002-328233 A JP 2001-247717 A JP-A-3-33719 Japanese Patent Laid-Open No. 3-24502 JP-A-4-194820 Japanese National Patent Publication No. 8-511812 Plastic Materials Course, Volume 17, Nikkan Kogyo Shimbun, “Fiber-Based Resin”, p. 121 (Showa 45)

The first problem of the present invention is that the optical anisotropy (Re, Rth) is small and substantially optically isotropic, the optical anisotropy (Re, Rth) is less dependent on humidity, and has a wavelength. It is to provide a cellulose acylate film having small dispersion and further less optical unevenness.
The second subject of the present invention is an optical compensation film, a polarizing plate or the like produced from a cellulose acylate film having a small optical anisotropy, a small humidity dependency, a small wavelength dispersion, and a small optical unevenness. It is to show that a material is excellent in viewing angle characteristics and to provide a liquid crystal display device using these materials.
By using a cellulose acylate film having a small optical anisotropy, a small humidity dependency, a small wavelength dispersion, and a small optical unevenness as a protective film for the polarizing plate, the optical characteristics of the polarizing plate can be improved. When used as a support for an optical compensation film, the optical performance of the optical compensation film itself can be extracted. By using these polarizing plates and optical compensation films in a liquid crystal display device, the contrast can be improved and the color can be improved.
Further, even when the film has the optical characteristics as described above, when used in a liquid crystal display device, for example, it has an effect of excellent contrast in a wide viewing angle, but on the other hand, there is a problem that rainbow unevenness occurs. there were.

  Therefore, the present invention is an optical film having negative birefringence, which, when used in various display devices such as a liquid crystal display device, prevents the occurrence of rainbow unevenness and the like and exhibits even better display characteristics. For the purpose of provision.

［式中、Ｒ ¹ はアルキル基またはアリール基を表し、Ｒ ² およびＲ ³ は、それぞれ独立に、水素原子、アルキル基またはアリール基を表す。］
数式（Ｉ）：１＜（ｎｘ−ｎｚ）／（ｎｘ−ｎｙ）
数式（II）：０．０００５≦Δｎ（ａ）≦０．５
（数式（II）において、Δｎ（ａ）は、下記数式で表される複屈折層（ａ）の複屈折率であり、数式（Ｉ）および下記数式において、ｎｘ、ｎｙおよびｎｚは、それぞれ複屈折層（ａ）におけるＸ軸、Ｙ軸およびＺ軸方向の屈折率を示す。ここで、Ｘ軸は複屈折層（ａ）の面内において最大の屈折率を示す軸方向であり、Ｙ軸は前記面内において、Ｘ軸に対して垂直な軸方向であり、Ｚ軸はＸ軸およびＹ軸に垂直な厚み方向を示す。
Δｎ（ａ）＝［（ｎｘ＋ｎｙ）／２］−ｎｚ）
２．Ｒｅ₍λ₎およびＲｔｈ₍λ₎が下記数式（Ｉ'）をみたすことを特徴とする上記１に記載の光学フィルム。
数式（Ｉ'）：｜Ｒｅ₍₄₀₀₎−Ｒｅ₍₇₀₀₎｜≦１０、かつ｜Ｒｔｈ₍₄₀₀₎−Ｒｔｈ₍₇₀₀₎｜≦３５
（式中、Ｒｅ₍λ₎は波長λｎｍにおける正面レターデーション値（単位：ｎｍ）、Ｒｔｈ₍λ₎は波長λｎｍにおける膜厚方向のレターデーション値（単位：ｎｍ）である。）
３．Ｒｅ及びＲｔｈの面内ばらつきが下記数式（III）及び（IV）を満たすことを特徴とする上記１または２に記載の光学フィルム。
（III）：｜Ｒｅ_(MAX)−Ｒｅ_(MIN)｜≦３
（IV） ：｜Ｒｔｈ_(MAX)−Ｒｔｈ_(MIN)｜≦５
（式中、Ｒｅ_(MAX)、Ｒｔｈ_(MAX)は任意に切り出した１ｍ四方のフィルムの最大レターデーション値、Ｒｅ_(MIN)、Ｒｔｈ_(MIN)は最小値である。）
４．積層体を構成する、前記セルロースアシレートフィルムである前記透明フィルム（ｂ）のＲｅ₍λ₎ 及びＲｔｈ₍λ₎が、下記数式（Ｖ）及び（ＶI）を満たすことを特徴とする上記１乃至３のいずれかに記載の光学フィルム。
数式（Ｖ）：０≦Ｒｅ₍₆₃₀₎≦１０、かつ｜Ｒｔｈ₍₆₃₀₎｜≦２５
数式（ＶI）：｜Ｒｅ₍₄₀₀₎−Ｒｅ₍₇₀₀₎｜≦１０、かつ｜Ｒｔｈ₍₄₀₀₎−Ｒｔｈ₍₇₀₀₎｜≦３５
（式中、Ｒｅ₍λ₎は波長λｎｍにおける正面レターデーション値（単位：ｎｍ）、Ｒｔｈ₍λ₎は波長λｎｍにおける膜厚方向のレターデーション値（単位：ｎｍ）である。）
５．セルロースアシレートフィルムが、フィルム膜厚方向のレターデーションＲｔｈを低下させる化合物を、下記数式（VII）及び（VIII）をみたす範囲で少なくとも一種含有することを特徴とする上記４に記載の光学フィルム。
数式（VII）：（Ｒｔｈ（Ａ）−Ｒｔｈ（０））／Ａ≦−１．０
数式（VIII）：０．０１≦Ａ≦３０
（ここで、Ｒｔｈ（Ａ）はＲｔｈを低下させる化合物をＡ％含有したフィルムのＲｔｈ（ｎｍ）を表し、Ｒｔｈ（０）はＲｔｈを低下させる化合物を含有しないフィルムのＲｔｈ（ｎｍ）を表す。なお、Ａはフィルム原料ポリマーの質量を１００としたときの化合物の質量（％）である。）
６．セルロースアシレートフィルムが、アシル置換度が２.８５〜３．００のセルロースアシレートに、Ｒｅ₍λ₎およびＲｔｈ₍λ₎を低下させる化合物を少なくとも１種、セルロースアシレート固形分に対して０．０１〜３０質量％含むことを特徴とする上記４に記載の光学フィルム。
７．セルロースアシレートフィルムが、フィルムの｜Ｒｅ_(400）−Ｒｅ₍₇₀₀₎｜および｜Ｒｔｈ₍₄₀₀₎−Ｒｔｈ₍₇₀₀₎｜を低下させる化合物を少なくとも１種、セルロースアシレート固形分に対して０．０１〜３０質量％含むことを特徴とする上記４に記載の光学フィルム。
８．セルロースアシレートフィルムが、フィルムの膜厚が１０〜１２０μｍであることを特徴とする上記４に記載の光学フィルム。
９．透明フィルム（ｂ）上に、直接、複屈折層（ａ）が積層されていることを特徴とする上記１乃至８のいずれかに記載の光学フィルム。
１０．複屈折層（ａ）を形成する材料が、非液晶性材料であることを特徴とする上記１乃至９のいずれかに記載の光学フィルム。
１１．非液晶性材料が、ポリアミド、ポリイミド、ポリエステル、ポリエーテルケトン、ポリアミドイミドおよびポリエステルイミドからなる群から選択される少なくとも一種のポリマー材料であることを特徴とする上記１０に記載の光学フィルム。
１２．最外層に、接着剤層および粘着剤層の少なくとも一方が積層された上記９乃至１１のいずれかに記載の光学フィルム。
１３．上記１乃至１２のいずれかに記載の光学フィルムを少なくとも１枚、偏光子の保護フィルムとして有することを特徴とする偏光板。
１４．液晶セルおよび光学部材を含み、液晶セルの少なくとも一方の表面に光学部材が配置された液晶パネルであって、光学部材が、上記１乃至１２のいずれかに記載の光学フィルムまたは上記１３に記載の偏光板であることを特徴とする液晶パネル。
１５．液晶パネルを含む液晶表示装置であって、液晶パネルが上記１４記載の液晶パネルであることを特徴とする液晶表示装置。
１６．上記１〜１２に記載の光学フィルム及び上記１３に記載の偏光板のいずれかを有することを特徴とする液晶表示装置。
１７．上記１〜１２のいずれかに記載の光学フィルム及び上記１３に記載の偏光板のいずれかを有することを特徴とするＶＡ液晶表示装置。
１８．液晶セルの上下両側に偏光板を有する上記１７に記載のＶＡ液晶表示装置において、少なくとも片側の偏光板のセル側に上記１〜１２のいずれかに記載の光学フィルムを有することを特徴とする液晶表示装置。
１９．光学異方性を低下させる化合物を含有するセルロースアシレートフィルムである透明フィルム（ｂ）の上に複屈折層（ａ）が積層された光学フィルムであって、複屈折層（ａ）が下記数式（Ｉ）、（II）の条件を満たし、かつ非液晶性材料から形成され、
前記光学異方性を低下させる化合物が、オクタノール−水分配係数が０ないし７であり、分子量が１５０以上３０００以下であり、かつ下記一般式（１３）で表されることを特徴とする光学フィルム。
一般式（１３）

［式中、Ｒ ¹ はアルキル基またはアリール基を表し、Ｒ ² およびＲ ³ は、それぞれ独立に、水素原子、アルキル基またはアリール基を表す。］
数式（Ｉ）：１＜（ｎｘ−ｎｚ）／（ｎｘ−ｎｙ）
数式（II）：０．０００５≦Δｎ（ａ）≦０．５
（数式（II）において、Δｎ（ａ）は、下記数式で表される複屈折層（ａ）の複屈折率であり、数式（Ｉ）および下記数式において、ｎｘ、ｎｙおよびｎｚは、それぞれ複屈折層（ａ）におけるＸ軸、Ｙ軸およびＺ軸方向の屈折率を示す。ここで、Ｘ軸は複屈折層（ａ）の面内において最大の屈折率を示す軸方向であり、Ｙ軸は前記面内において、Ｘ軸に対して垂直な軸方向であり、Ｚ軸はＸ軸およびＹ軸に垂直な厚み方向を示す。
Δｎ（ａ）＝［（ｎｘ＋ｎｙ）／２］−ｎｚ）
２０．前記非液晶性材料が、ポリアミド、ポリイミド、ポリエステル、ポリエーテルケトン、ポリアミドイミドおよびポリエステルイミドからなる群から選択される少なくとも一種のポリマー材料であることを特徴とする上記１９に記載の光学フィルム。
本発明は、上記１〜２０に係る発明であるが、以下、それ以外の事項についても記載している。 As a result of intensive studies, the inventors of the present invention have found that a liquid crystal display device excellent in display quality can be achieved by reducing fluctuations in humidity dependency, wavelength dispersion, Re, and Rth of the optical film.
According to the present invention, the following optical film, polarizing plate, and liquid crystal display device are provided, and the above problems are solved.
1. An optical film birefringent layer (a) is laminated on the transparency film is a cellulose acylate film containing the compound decreasing optical anisotropy (b), the birefringent layer (a) is below Re retardation value and Rth retardation value satisfying the conditions of the mathematical formulas (I) and (II) and measured in an environment of 25 ° C. and 10% RH, and Re retardation value and Rth measured in an environment of 25 ° C. and 80% RH the difference of the retardation value, within 20nm each state, and are within 50nm,
The optical film, wherein the compound for reducing optical anisotropy has an octanol-water partition coefficient of 0 to 7, a molecular weight of 150 or more and 3000 or less, and represented by the following general formula (13): .
Formula (13)

[Wherein, R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group, or an aryl group. ]
Formula (I): 1 <(nx-nz) / (nx-ny)
Formula (II): 0.0005 ≦ Δn (a) ≦ 0.5
(In the formula (II), Δn (a) is the birefringence of the birefringent layer (a) represented by the following formula, and in the formula (I) and the following formula, nx, ny and nz are respectively double The refractive indexes of the refractive layer (a) in the X-axis, Y-axis, and Z-axis directions are shown, where the X-axis is the axial direction indicating the maximum refractive index in the plane of the birefringent layer (a), and the Y-axis. Is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis.
Δn (a) = [(nx + ny) / 2] −nz)
2. 2. The optical film as described in 1 above, wherein Re ₍ λ ₎ and Rth ₍ λ ₎ satisfy the following formula (I ′).
Formula (I ′): | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35
(In the formula, Re ₍ λ ₎ is the front retardation value (unit: nm) at the wavelength λnm, and Rth ₍ λ ₎ is the retardation value (unit: nm) in the film thickness direction at the wavelength λnm.)
3. 3. The optical film as described in 1 or 2 above, wherein in-plane variations in Re and Rth satisfy the following formulas (III) and (IV):
(III): | Re _(MAX) −Re _(MIN) | ≦ 3
(IV): | Rth _(MAX) −Rth _(MIN) | ≦ 5
(In the formula, Re _(MAX) and Rth _(MAX) are the maximum retardation values of 1 m square film cut out arbitrarily, and Re _(MIN) and Rth _(MIN) are the minimum values.)
4). Constituting the laminate, R e of the transparent film wherein a cellulose acylate film _(b) (λ) and Rth _(lambda), wherein the score was satisfy the following formula (V) and (VI) 4. The optical film as described in any one of 1 to 3 above.
Formula (V): 0 ≦ Re ₍₆₃₀₎ ≦ 10 and | Rth ₍₆₃₀₎ | ≦ 25
Formula (VI): | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35
(In the formula, Re ₍ λ ₎ is the front retardation value (unit: nm) at the wavelength λnm, and Rth ₍ λ ₎ is the retardation value (unit: nm) in the film thickness direction at the wavelength λnm.)
5). 5. The optical film as described in 4 above, wherein the cellulose acylate film contains at least one compound that reduces the retardation Rth in the film thickness direction within a range satisfying the following formulas (VII) and (VIII).
Formula (VII): (Rth (A) −Rth (0)) / A ≦ −1.0
Formula (VIII): 0.01 ≦ A ≦ 30
(Here, Rth (A) represents Rth (nm) of a film containing A% of a compound that reduces Rth, and Rth (0) represents Rth (nm) of a film not containing a compound that reduces Rth. In addition, A is the mass (%) of the compound when the mass of the film raw material polymer is 100.)
6). The cellulose acylate film is a cellulose acylate having an acyl substitution degree of 2.85 to 3.00, at least one compound for reducing Re ₍ λ ₎ and Rth ₍ λ _), and 0 for the cellulose acylate solid content. The optical film as described in 4 above, comprising 0.01 to 30% by mass.
7). The cellulose acylate film has at least one compound that lowers | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | The optical film as described in 4 above, which comprises from 01 to 30% by mass.
8). 5. The optical film as described in 4 above, wherein the cellulose acylate film has a film thickness of 10 to 120 μm.
9. 9. The optical film as described in any one of 1 to 8 above, wherein the birefringent layer (a) is directly laminated on the transparent film (b).
10. 10. The optical film as described in any one of 1 to 9 above, wherein the material forming the birefringent layer (a) is a non-liquid crystalline material.
11. 11. The optical film as described in 10 above, wherein the non-liquid crystalline material is at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide .
12 The optical film according to any one of 9 to 11, wherein at least one of an adhesive layer and a pressure-sensitive adhesive layer is laminated on the outermost layer.
13. At least one optical film according to any one of the upper Symbol 1 to 12, a polarizing plate characterized by having as a protective film for the polarizer.
14 14. A liquid crystal panel comprising a liquid crystal cell and an optical member, wherein the optical member is disposed on at least one surface of the liquid crystal cell, wherein the optical member is the optical film according to any one of 1 to 12 or 13 above. A liquid crystal panel characterized by being a polarizing plate.
15. A liquid crystal display comprising a liquid crystal panel, liquid crystal display device having a liquid crystal panel characterized in that it is a liquid crystal panel of the mounting said 14 SL.
16. 14. A liquid crystal display device comprising any one of the optical film described in 1 to 12 above and the polarizing plate described in 13 above.
17. 14. A VA liquid crystal display device comprising the optical film according to any one of 1 to 12 and the polarizing plate according to 13 .
18. In the VA liquid crystal display device according to above SL 17 having polarizing plates on both upper and lower sides of the liquid crystal cell, and having an optical film according to any one of the above 1 to 12 on the cell side of the at least one side of the polarizing plate Liquid crystal display device.
19. An optical film in which a birefringent layer (a) is laminated on a transparent film (b) which is a cellulose acylate film containing a compound for reducing optical anisotropy, and the birefringent layer (a) is represented by the following formula: Satisfying the conditions of (I) and (II) and formed from a non-liquid crystalline material;
The optical film, wherein the compound for reducing optical anisotropy has an octanol-water partition coefficient of 0 to 7, a molecular weight of 150 to 3,000, and represented by the following general formula (13): .
Formula (13)

[Wherein, R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group, or an aryl group. ]
Formula (I): 1 <(nx-nz) / (nx-ny)
Formula (II): 0.0005 ≦ Δn (a) ≦ 0.5
(In the formula (II), Δn (a) is the birefringence of the birefringent layer (a) represented by the following formula, and in the formula (I) and the following formula, nx, ny and nz are respectively double The refractive indexes of the refractive layer (a) in the X-axis, Y-axis, and Z-axis directions are shown, where the X-axis is the axial direction indicating the maximum refractive index in the plane of the birefringent layer (a), and the Y-axis. Is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis.
Δn (a) = [(nx + ny) / 2] −nz)
20. 20. The optical film as described in 19 above, wherein the non-liquid crystalline material is at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide.
Although this invention is invention concerning said 1-20, hereafter, the other matter is also described.

According to the present invention, the optical anisotropy (Re, Rth) is small and substantially optically isotropic, the optical anisotropy (Re, Rth) is less dependent on humidity, and the wavelength dispersion is small. Furthermore, it is shown that optical materials such as an optical compensation film and a polarizing plate produced with a cellulose acylate film with little optical unevenness are excellent in viewing angle characteristics, and a polarizing plate and a liquid crystal display using these. An apparatus is provided.
If the optical compensation film and polarizing plate of the invention are used, there will be little change in color from an oblique angle, there will be little unevenness on the screen, and the display performance will also be excellent in humidity dependence, and the occurrence of rainbow unevenness will also be suppressed. A thin liquid crystal display device with excellent display quality can be realized. Furthermore, a thin liquid crystal display device excellent in display quality with reduced panel unevenness after thermo can be realized.

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

[Substitution degree of cellulose acylate]
Next, the cellulose acylate produced from the above-mentioned cellulose as a raw material and preferably used in the present invention will be described. The cellulose acylate of the present invention is obtained by acylating a hydroxyl group of cellulose, and the substituent can be preferably used from an acyl group having 2 carbon atoms to an acyl group having 22 carbon atoms. In the cellulose acylate of the present invention, the degree of substitution of cellulose with a hydroxyl group is not particularly limited, but the degree of substitution of acetic acid substituted with a hydroxyl group of cellulose and a fatty acid having 3 to 22 carbon atoms is measured, and the degree of substitution is calculated. Obtainable. As a measuring method, it can carry out according to ASTM D-817-91.

  As described above, in the cellulose acylate of the present invention, the degree of substitution of the cellulose with a hydroxyl group is not particularly limited, but the degree of acyl substitution with the hydroxyl group of cellulose is preferably 2.50 to 3.00. Furthermore, the substitution degree is preferably 2.75 to 3.00, and more preferably 2.85 to 3.00.

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

  As a result of intensive studies by the inventor of the present invention, among the acyl substituents substituted on the above-mentioned cellulose hydroxyl group, in the case of substantially consisting of at least two kinds of acetyl group / propionyl group / butanoyl group, the total substitution It was found that the optical anisotropy of the cellulose acylate film can be lowered when the degree is 2.50 to 3.00. The degree of acyl substitution is more preferably 2.60 to 3.00, still more preferably 2.65 to 3.00.

[Degree of polymerization of cellulose acylate]
The degree of polymerization of cellulose acylate preferably used in the present invention is 180 to 700 in terms of viscosity average polymerization degree, and in cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. . If the degree of polymerization is too high, the viscosity of the cellulose acylate dope solution becomes high, and film production becomes difficult due to casting. If the degree of polymerization is too low, the strength of the produced film will decrease. The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). This is described in detail in JP-A-9-95538.
The molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) is small, and the molecular weight distribution. Is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and most preferably 1.0 to 1.6. preferable.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is in the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of the cellulose acylate film of the present invention, the water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass or less. It is a cellulose acylate having a water content. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In the present invention, in order to bring the moisture content of the cellulose acylate to the above range, it is necessary to dry the cellulose acylate, and the method is not particularly limited as long as the desired moisture content is obtained. These cellulose acylates of the present invention are described in detail on page 7 to page 12 of the raw material cotton and the synthesis method in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in.

  The cellulose acylate of the present invention can be used alone or in combination of two or more kinds of cellulose acylates as long as the substituent, the degree of substitution, the degree of polymerization, the molecular weight distribution and the like are in the above-mentioned ranges.

[Additive to cellulose acylate]
In the cellulose acylate solution of the present invention, various additives (for example, compounds that reduce optical anisotropy, wavelength dispersion regulators, ultraviolet inhibitors, plasticizers, deterioration inhibitors) according to applications in each preparation step. , Fine particles, optical property modifiers, etc.) can be added and these are described below. In addition, the additive may be added at any time in the dope preparation process, or may be performed by adding an additive to the final preparation process of the dope preparation process.
The cellulose acylate solution is at least one compound that reduces the optical anisotropy of the cellulose acylate film of the invention, particularly the retardation Rth in the film thickness direction, within the range satisfying the following formulas (ii) and (iii). It is preferable to contain.
Formula (ii): (Rth (A) −Rth (0)) / A ≦ −1.0
Formula (iii): 0.01 ≦ A ≦ 30
The above formulas (ii) and (iii) are expressed by the following formula (ii): (Rth (A) −Rth (0)) / A ≦ −2.0
Formula (iii): 0.05 ≦ A ≦ 25
More preferably,
Formula (ii): (Rth (A) −Rth (0)) / A ≦ −3.0
Formula (iii): 0.1 ≦ A ≦ 20
More preferably.
Here, Rth (A) is Rth (nm) of a film containing A% of a compound that reduces Rth,
Rth (0) is Rth (nm) of a film not containing a compound that lowers Rth,
A is the mass (%) of the compound when the mass of the film raw material polymer is 100
It is.

[Structural characteristics of compounds that reduce optical anisotropy of cellulose acylate film]
The compound that reduces the optical anisotropy of the cellulose acylate film will be described. As a result of intensive studies, the present inventors have sufficiently reduced the optical anisotropy by using a compound that suppresses the orientation of cellulose acylate in the film in the plane and in the film thickness direction, so that Re and Rth are It was close to zero. For this purpose, it is advantageous that the compound that lowers the optical anisotropy is sufficiently compatible with cellulose acylate, and the compound itself does not have a rod-like structure or a planar structure. Specifically, when a plurality of planar functional groups such as aromatic groups are provided, a structure having these functional groups in a non-planar rather than the same plane is advantageous.

(Log P value)
In producing the cellulose acylate film of the present invention, octanol is among the compounds that reduce the optical anisotropy by inhibiting the cellulose acylate in the film from being oriented in the plane and in the film thickness direction as described above. -Compounds with a water partition coefficient (Log P value) of 0 to 7 are preferred. When the LogP value is in the above range, there are advantages such that the compatibility with the cellulose acylate is sufficient and the film is not clouded or powdered, the hydrophilicity is appropriate, and the film has water resistance. A more preferable range for the log P value is 1 to 6, and a particularly preferable range is 1.5 to 5.
The octanol-water partition coefficient (Log P value) can be measured by a flask immersion method described in JIS Japanese Industrial Standard Z7260-107 (2000). Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement. As a calculation method, Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987).), Viswanadhan's fragmentation method (J. Chem. Inf. Comput. Sci., 29, 163 (1989).) The Broto's fragmentation method (Eur. J. Med. Chem.-Chim. Theor., 19, 71 (1984).) And the like are preferably used, but the Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27 , 21 (1987). When the LogP value of a certain compound varies depending on the measurement method or calculation method, it is preferable to determine whether the compound is within the scope of the present invention by the Crippen's fragmentation method.

[Physical properties of compounds that reduce optical anisotropy]
The compound that reduces optical anisotropy may or may not contain an aromatic group. The compound that reduces the optical anisotropy preferably has a molecular weight of 150 or more, 3000 or less, more preferably 170 or more and 2000 or less, and particularly preferably 200 or more and 1000 or less. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.
The compound that reduces optical anisotropy is preferably a liquid at 25 ° C. or a solid having a melting point of 25 to 250 ° C., more preferably a liquid at 25 ° C. or a solid having a melting point of 25 to 200 ° C. It is. Moreover, it is preferable that the compound which reduces optical anisotropy does not volatilize in the process of dope casting for cellulose acylate film production and drying.
The addition amount of the compound that decreases the optical anisotropy is preferably 0.01 to 30% by mass, more preferably 1 to 25% by mass, and more preferably 5 to 20% by mass of the cellulose acylate. Is particularly preferred.
The compound that decreases the optical anisotropy may be used alone, or two or more compounds may be mixed and used in an arbitrary ratio.
The timing for adding the compound for reducing the optical anisotropy may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

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

  Although the specific example of the compound which reduces the optical anisotropy of the cellulose acylate film preferably used by this invention below is shown, this invention is not limited to these compounds.

The logP values described in the present invention are determined by the Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987)).
The compound of the general formula (13) will be described.

Formula (13)

[Wherein, R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group, or an aryl group. The total number of carbon atoms of R ¹ , R ² and R ³ is particularly preferably 10 or more. ]
As the substituent for R ¹ , R ² and R ³ , a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group and a sulfonamide group are preferable, and an alkyl group, an aryl group, an alkoxy group, a sulfone group and a sulfonamide group Is particularly preferred.
Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 Is particularly preferred. Preferable specific examples of the alkyl group include, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclooctyl, nonyl, adamantyl, Examples include decyl, t-octyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and didecyl.
As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms such as phenyl, biphenyl, terphenyl, naphthyl, binaphthyl and triphenylphenyl are particularly preferable.
Preferred examples of the compound represented by the general formula (13) are shown below, but the present invention is not limited to these specific examples.

General formula (2):

In General Formula (2), R ³¹ represents an alkyl group or an aryl group, and R ³² and R ³³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Here, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and 1 to 12 carbon atoms. Is most preferred. As the cyclic alkyl group, a cyclohexyl group is particularly preferable. The aryl group preferably has 6 to 36 carbon atoms, and more preferably 6 to 24 carbon atoms.

  The above alkyl group and aryl group may have a substituent. Examples of the substituent include a halogen atom (for example, chlorine, bromine, fluorine and iodine), an alkyl group, an aryl group, an alkoxy group, an aryloxy group, An acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a sulfonylamino group, a hydroxy group, a cyano group, an amino group, and an acylamino group are preferable, and a halogen atom, an alkyl group, an aryl group, an alkoxy group, and an aryloxy are more preferable. Group, sulfonylamino group and acylamino group, particularly preferably alkyl group, aryl group, sulfonylamino group and acylamino group.

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

[Chromatic dispersion modifier]
A compound for reducing the wavelength dispersion of the cellulose acylate film (hereinafter also referred to as a wavelength dispersion adjusting agent) will be described. In order to improve the Rth wavelength dispersion of the cellulose acylate film of the present invention, the following formulas (v) and (vi) are used to reduce the Rth wavelength dispersion ΔRth represented by the following formula (iv). It is preferable to contain at least one kind within the range to satisfy.
Formula (iv): ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ |
Formula (v): (ΔRth (B) −ΔRth (0)) / B ≦ −2.0
Formula (vi): 0.01 ≦ B ≦ 30
The above formulas (v) and (vi) are expressed by the following formula (v): (ΔRth (B) −ΔRth (0)) / B ≦ −3.0.
Formula (vi): 0.05 ≦ B ≦ 25
More preferably,
Formula (v): (ΔRth (B) −ΔRth (0)) / B ≦ −4.0
Formula (vi): 0.1 ≦ B ≦ 20
More preferably.
here,
Rth ₍₄₀₀₎ means Rth (nm) at 400 nm,
Rth ₍₇₀₀₎ means Rth (nm) at 700 nm,
ΔRth (B) means ΔRth (nm) of a film containing B mass% of a compound that reduces ΔRth,
ΔRth (0) means ΔRth (nm) of a film not containing a compound that reduces ΔRth,
B is the mass (%) of the compound when the mass of the film raw material polymer is 100
It is.
The above-mentioned wavelength dispersion adjusting agent has at least a compound having absorption in the ultraviolet region of 200 to ₄₀₀ nm and reducing | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | The wavelength dispersion of Re and Rth of the cellulose acylate film was adjusted by including 0.01 to 30% by mass of one type, cellulose acylate solid content.

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

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

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

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

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

(Compound addition amount)
The addition amount of the chromatic dispersion adjusting agent preferably used in the present invention is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass, more preferably 0.1 to 20% by mass of the cellulose acylate. 2 to 10% by weight is particularly preferred.

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

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

  As the benzotriazole-based compound, those represented by the general formula (101) are preferably used as the wavelength dispersion adjusting agent of the present invention.

Formula ^{(101): Q 1 -Q 2} -OH
(In the formula, Q ¹ represents a nitrogen-containing aromatic heterocycle, and Q ² represents an aromatic ring.)

Q ¹ represents a nitrogen-containing aromatic heterocycle, preferably a 5- to 7-membered nitrogen-containing aromatic heterocycle, more preferably a 5- to 6-membered nitrogen-containing aromatic heterocycle, such as imidazole, Pyrazole, triazole, tetrazole, thiazole, oxazole, selenazole, benzotriazole, benzothiazole, benzoxazole, benzoselenazole, thiadiazole, oxadiazole, naphthothiazole, naphthoxazole, azabenzimidazole, purine, pyridine, pyrazine, pyrimidine, pyridazine , Triazine, triazaindene, tetrazaindene and the like, more preferably a 5-membered nitrogen-containing aromatic heterocycle, specifically imidazole, pyrazole, triazole, tetrazole, thiazole, oxazol. , Benzotriazole, benzothiazole, benzoxazole, thiadiazole, oxadiazole preferably, particularly preferably benzotriazole.
The nitrogen-containing aromatic heterocycle represented by Q ¹ may further have a substituent, and the substituent T described below can be applied as the substituent. In addition, when there are a plurality of substituents, each may be condensed to form a ring.

The aromatic ring represented by Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring or a naphthalene ring), and more preferably an aromatic carbon ring having 6 to 20 carbon atoms. A hydrogen ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms. More preferred is a benzene ring.
The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.
The aromatic ring represented by Q ² is preferably an aromatic hydrocarbon ring, more preferably a naphthalene ring or a benzene ring, and particularly preferably a benzene ring. Q ² may further have a substituent, and the following substituent T is preferred.
As the substituent T, for example,
Alkyl group [preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n- Examples include decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl and the like. ],
Alkenyl group [preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, and examples thereof include vinyl, allyl, 2-butenyl, 3-pentenyl and the like. ],
Alkynyl group [preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, and examples thereof include propargyl and 3-pentynyl. ],
An aryl group [preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl and the like. ],
A substituted or unsubstituted amino group [preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino; Etc. ],
Alkoxy group [preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, and examples thereof include methoxy, ethoxy, butoxy and the like. ],
Aryloxy group [preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy, 2-naphthyloxy and the like. ],
Acyl group [preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, and pivaloyl. ],
Alkoxycarbonyl group [preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonyl and ethoxycarbonyl. ],
Aryloxycarbonyl group [preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, and particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl. ],
Acyloxy group [preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetoxy and benzoyloxy. ],
Acylamino group [preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino. ],
Alkoxycarbonylamino group [preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonylamino. ],
Aryloxycarbonylamino group [preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, and examples thereof include phenyloxycarbonylamino. ],
Sulfonylamino group [preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include methanesulfonylamino and benzenesulfonylamino. ],
Sulfamoyl group [preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, and particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc. Can be mentioned. ],
Carbamoyl group [preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl and the like. ],
An alkylthio group [preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include methylthio and ethylthio. ],
Arylthio group [preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include phenylthio. ],
A sulfonyl group [preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include mesyl and tosyl. ],
Sulfinyl group [preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include methanesulfinyl and benzenesulfinyl. ],
Ureido group [preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include ureido, methylureido, and phenylureido. ],
Phosphoric acid amide group [preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, such as diethyl phosphoric acid amide and phenylphosphoric acid amide. ],
Heterocyclic group [preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom, specifically imidazolyl, pyridyl, quinolyl, furyl and piperidyl Morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl and the like. ],
A silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include trimethylsilyl and triphenylsilyl);
In addition, hydroxy group, mercapto group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, etc. Is mentioned.
These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

  Preferred as the general formula (101) is a compound represented by the following general formula (101-A).

General formula (101-A)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a substituent)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or a substituent. Applicable. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.
R ¹ and R ³ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably an alkyl group having 1 to 12 carbon atoms (preferably 4 to 12 carbon atoms).

R ² and R ⁴ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and a C1-12 alkyl group, particularly preferably a hydrogen atom and a methyl group, most preferably It is a hydrogen atom.

R ⁵ and R ⁸ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and a C1-12 alkyl group, particularly preferably a hydrogen atom and a methyl group, most preferably a hydrogen atom. Is an atom.

R ⁶ and R ⁷ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, aryloxy groups, hydroxy groups, and halogen atoms, more preferably hydrogen atoms. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and a halogen atom, and particularly preferably a hydrogen atom and a chlorine atom.
More preferable as the general formula (101) is a compound represented by the following general formula (101-B).

General formula (101-B)

(In formula, R < ¹ >, R < ³ >, R < ⁶ > and R < ⁷ > are synonymous with those in general formula (101-A), and their preferred ranges are also the same.)
Specific examples of the compound represented by the general formula (101) are given below, but the present invention is not limited to the following specific examples.

Among the benzotriazole compounds exemplified in the above examples, when the cellulose acylate film of the present invention was produced without including those having a molecular weight of 320 or less, it was confirmed that it was advantageous in terms of storage stability.
In addition, as the benzophenone compound which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (102) are preferably used.

General formula (102)

In general formula (102), Q ¹ and Q ² each independently represents an aromatic ring. X represents NR (R represents a hydrogen atom or a substituent), an oxygen atom or a sulfur atom.
The aromatic ring represented by Q ¹ and Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring represented by Q ¹ and Q ² is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring, a naphthalene ring, etc.). More preferably, it is an aromatic hydrocarbon ring having 6 to 20 carbon atoms, and more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms. More preferred is a benzene ring.
The aromatic heterocycle represented by Q ¹ and Q ² is preferably an aromatic heterocycle containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, Examples include quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzothiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.
The aromatic ring represented by Q ¹ and Q ² is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, and still more preferably a substituted or unsubstituted benzene ring. It is.
Q ¹ and Q ² may further have a substituent, and the substituent T described later is preferable, but the substituent does not contain a carboxylic acid, a sulfonic acid, or a quaternary ammonium salt. Further, when possible, substituents may be linked to form a ring structure.

X represents NR (R represents a hydrogen atom or a substituent. Substituent T described later can be applied as the substituent), an oxygen atom or a sulfur atom, and X is preferably NR (R is preferably acyl. A sulfonyl group, and these substituents may be further substituted), or an oxygen atom, and particularly preferably an oxygen atom.
As the substituent T, the above-described substituent T of the general formula (101) is applied as it is, but the substituent does not contain carboxylic acid, sulfonic acid, or quaternary ammonium salt.
These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

  The compound represented by the general formula (102) is preferably a compound represented by the following general formula (102-A).

Formula (102-A)

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represents a hydrogen atom or a substituent.)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represents a hydrogen atom or a substituent, and the substituent T described above applies as the substituent it can. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁸ and R ⁹ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups, alkoxy groups, An aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, still more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms. And particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ² is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or a carbon number. An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, and more preferably an alkoxy group having 1 to 20 carbon atoms. Group, particularly preferably an alkoxy group having 1 to 12 carbon atoms.

R ⁷ is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or a carbon number. An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and 1 to 20 carbon atoms. Alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and still more preferably a methyl group), particularly preferably a methyl group or a hydrogen atom.

  More preferable as the general formula (102) is a compound represented by the following general formula (102-B).

General formula (102-B)

(Wherein R ¹⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group.)

R ¹⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. Applicable.

R ¹⁰ is preferably a substituted or unsubstituted alkyl group, more preferably a substituted or unsubstituted alkyl group having 5 to 20 carbon atoms, and still more preferably a substituted or unsubstituted alkyl group having 5 to 12 carbon atoms. (Including n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substitution of 6 to 12 carbon atoms or An unsubstituted alkyl group (2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group).

The compound represented by the general formula (102) can be synthesized by a known method described in JP-A-11-12219.
Specific examples of the compound represented by the general formula (102) are given below, but the present invention is not limited to the following specific examples.

  As the compound containing a cyano group, which is one of the wavelength dispersion adjusting agents used in the present invention, those represented by the general formula (103) are preferably used.

General formula (103)

(In the formula, Q ¹ and Q ² each independently represent an aromatic ring. X ¹ and X ² represent a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, an aromatic group. Represents a heterocycle.)
The aromatic ring represented by Q ¹ and Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

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

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

The aromatic ring represented by Q ¹ and Q ² is preferably an aromatic hydrocarbon ring, more preferably a benzene ring.
Q ¹ and Q ² may further have a substituent, and a substituent T described later is preferable.
Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

X ¹ and X ² each represent a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle. The substituent T described above can be applied to the substituents represented by X ¹ and X ² . In addition, the substituent represented by X ¹ and X ² may be further substituted with another substituent, and X ¹ and X ² may each be condensed to form a ring structure.

X ¹ and X ² are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle, and more preferably a cyano group, a carbonyl group, a sulfonyl group, An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, 6 carbon atoms). ~ 12 aryl groups and combinations thereof.
As the general formula (103), a compound represented by the following general formula (103-A) is preferable.

General formula (103-A)

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a substituent. X ¹ and X ² Are the same as those in formula (103), and the preferred range is also the same.)

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represents a hydrogen atom or a substituent. Is applicable. These substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.
R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, An alkoxy group, an aryloxy group, a hydroxy group and a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, still more preferably a hydrogen atom and a C1-12 alkyl. A group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.
R ³ and R ⁸ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, aryloxy group, hydroxy group, halogen atom, more preferably a hydrogen atom. A C1-20 alkyl group, a C0-20 amino group, a C1-12 alkoxy group, a C6-12 aryloxy group, a hydroxy group, more preferably a hydrogen atom, a C1-12 alkyl group, C1 To 12 alkoxy groups, particularly preferably a hydrogen atom.
More preferable as the general formula (103) is a compound represented by the following general formula (103-B).

General formula (103-B)

(Wherein R ³ and R ⁸ have the same meanings as those in formula (103-A), and preferred ranges are also the same. X ³ represents a hydrogen atom or a substituent.)
X ³ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with another substituent. X ³ is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group or an aromatic heterocyclic ring, more preferably a cyano group, a carbonyl group, a sulfonyl group or an aromatic heterocyclic ring. More preferably a cyano group or a carbonyl group, particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, aryl having 6 to 12 carbon atoms). Group and a combination thereof).

  More preferable as the general formula (103) is a compound represented by the general formula (103-C).

General formula (103-C)

(In the formula, R ³ and R ⁸ have the same meanings as those in formula (103-A), and preferred ranges are also the same. R ²¹ represents a C1-20 alkyl group.)

When R ³ and R ⁸ are both hydrogen, R ²¹ is preferably a C2-12 alkyl group, more preferably a C4-12 alkyl group, and still more preferably a C6-12 alkyl group. And particularly preferably an n-octyl group, a tert-octyl group, a 2-ethylhexyl group, an n-decyl group, and an n-dodecyl group, and most preferably a 2-ethylhexyl group.

When R ³ and R ⁸ are other than hydrogen, R ²¹ is preferably an alkyl group having a molecular weight of 300 or more and a carbon number of 20 or less, represented by the general formula (103-C). .

  The compound represented by the general formula (103) of the present invention can be synthesized by the method described in Journal of American Chemical Society 63, 3452 (1941).

  Specific examples of the compound represented by the general formula (103) are given below, but the present invention is not limited to the following specific examples.

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the cellulose acylate film of the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The silicon dioxide fine particles preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

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

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

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

In order to obtain a cellulose acylate film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a dispersion of fine particles. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are mixed with stirring in advance, adding this fine particle dispersion to a small amount of cellulose acylate solution separately prepared, stirring and dissolving, and further mixing with the main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add the fine particles to this and disperse it with a disperser to make this fine particle additive solution. There is also a way to do it. The present invention is not limited to these methods, but the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

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

[Plasticizer, degradation inhibitor, release agent]
In addition to the above-mentioned compound that optically reduces anisotropy and the wavelength dispersion adjusting agent, the cellulose acylate film of the present invention has various additives (for example, a plasticizer, an ultraviolet ray, etc.) in each preparation step. Inhibitors, degradation inhibitors, release agents, infrared absorbers, etc.), which may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and similarly, mixing of a plasticizer is described in, for example, JP-A-2001-151901. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the dope preparation step, but may be added by adding an additive to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a cellulose acylate film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For example, it is described in Japanese Patent Application Laid-Open No. 2001-151902, but these are conventionally known techniques. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.

[Rate of compound addition]
In the cellulose acylate film of the present invention, the total amount of compounds having a molecular weight of 3000 or less is preferably 5 to 45% with respect to the mass of cellulose acylate. More preferably, it is 10-40%, More preferably, it is 15-30%. As described above, these compounds include compounds that reduce optical anisotropy, wavelength dispersion regulators, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, etc. Is preferably 3000 or less, more preferably 2000 or less, and even more preferably 1000 or less. When the total amount of these compounds is 5% or less, the properties of cellulose acylate alone are likely to be obtained, and there are problems such as that the optical performance and physical strength are likely to vary with changes in temperature and humidity. Moreover, when the total amount of these compounds is 45% or more, problems such as exceeding the limit of compatibility of the compounds in the cellulose acylate film and depositing on the film surface and causing the film to become cloudy (crying out of the film) occur. It becomes easy.

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

As described above, for the cellulose acylate film of the present invention, a chlorinated halogenated hydrocarbon may be used as a main solvent, and as described in JIII Journal of Technical Disclosure 2001-1745 (pages 12 to 16), A non-chlorine solvent may be used as the main solvent, and is not particularly limited for the cellulose acylate film of the present invention.
In addition, the solvent for the cellulose acylate solution and film of the present invention is disclosed in the following patents, including the dissolution method, and is a preferred embodiment. They are, for example, JP 2000-95876, JP 12-95877, JP 10-324774, JP 8-152514, JP 10-330538, JP 9-95538, JP 9-95557, JP 10-10. -235664, JP-A-12-63534, JP-A-11-21379, JP-A-10-182853, JP-A-10-278056, JP-A-10-279702, JP-A-10-323853, JP-A-10-237186, JP-A-11-60807. JP-A-11-152342, JP-A-11-292988, JP-A-11-60752, JP-A-11-60752, and the like. According to these publications, not only the preferred solvent for the cellulose acylate of the present invention, but also the solution physical properties and coexisting substances to be coexisted are described, which is also a preferred embodiment in the present invention.

[Manufacturing process of cellulose acylate film]
[Dissolution process]
The method for dissolving the cellulose acylate solution (dope) of the present invention is not particularly limited, and it may be performed at room temperature or further by a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding the preparation of the cellulose acylate solution in the present invention, and further the steps of solution concentration and filtration associated with the dissolution step, the Technical Report of the Japan Society of Invention (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention) The manufacturing process described in detail on pages 22 to 25 is preferably used.

[Casting, drying, winding process]
Next, a method for producing a film using the cellulose acylate solution of the present invention will be described. For the method and equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is fed from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support. The both ends of the obtained web are sandwiched between clips, transported by a tenter while holding the width and dried, and then the obtained film is mechanically transported by a roll group of a drying device, dried, and then rolled by a winder Wind up to a predetermined length. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film or the silver halide photographic light-sensitive material which is an optical member for electronic display, which is the main use of the cellulose acylate film of the present invention, the solution casting film forming apparatus In addition, a coating apparatus is often added for surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, and a protective layer. These are described in detail on pages 25-30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society for Invention). Including), metal support, drying, peeling and the like, and can be preferably used in the present invention.
Moreover, 10-120 micrometers is preferable, as for the thickness of a cellulose acylate film, 20-100 micrometers is more preferable, and 30-90 micrometers is more preferable.

[Humidity dependency of Re and Rth of film]
It is preferable that both the in-plane retardation Re and the thickness direction retardation Rth of the cellulose acylate film of the present invention are small in change due to humidity. Specifically, the difference ΔRe (= Re 10% RH−Re 80% RH) between the Rth value at 25 ° C. and 10% RH and the Re value at 25 ° C. and 80% RH is preferably 0 to 20 nm. More preferably, it is 0-15 nm, More preferably, it is 0-10 nm. Further, the Rth value difference ΔRth (= Rth 10% RH−Rth 80% RH) is preferably 0 to 50 nm. More preferably, it is 0-40 nm, More preferably, it is 0-30 nm.

[Equilibrium moisture content of film]
The equilibrium moisture content of the cellulose acylate film of the present invention is 25 ° C. at 80 ° C. regardless of the film thickness so as not to impair the adhesion with a water-soluble polymer such as polyvinyl alcohol when used as a protective film of a polarizing plate. The equilibrium moisture content at% RH is preferably 0 to 4%. It is more preferably 0.1 to 3.5%, and particularly preferably 1 to 3%. An equilibrium moisture content of 4% or more is not preferable because the dependence of retardation due to humidity change becomes too large when used as a support for an optical compensation film.
The moisture content was measured by measuring the cellulose acylate film sample 7 mm × 35 mm of the present invention by the Karl Fischer method using a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both Mitsubishi Chemical Corporation). . The moisture content (g) was calculated by dividing by the sample mass (g).

[Water permeability of film]
The moisture permeability of the cellulose acylate film used in the optical compensation sheet of the present invention is measured under the conditions of a temperature of 60 ° C. and a humidity of 95% RH based on JIS standard JISZ0208, and converted to a film thickness of 80 μm, 400 to 2000 g / m ² · 24h is preferred. More preferably 500~1800g / m ² · 24h, and particularly preferably 600~1600g / m ² · 24h. If it exceeds 2000 g / m ² · 24 h, the tendency of the absolute value of the humidity dependence of the Re and Rth values of the film to exceed 0.5 nm /% RH becomes strong. Also, when an optically anisotropic film is formed by laminating an optically anisotropic layer on the cellulose acylate film of the present invention, the absolute value of the humidity dependence of the Re value and Rth value tends to exceed 0.5 nm /% RH. It becomes strong and is not preferable. When this optical compensation sheet or polarizing plate is incorporated in a liquid crystal display device, it causes a change in color and a decrease in viewing angle. In addition, when the moisture permeability of the cellulose acylate film is less than 400 g / m ² · 24 h, when the polarizing plate is produced by sticking to both surfaces of the polarizing film, the cellulose acylate film prevents the adhesive from being dried. Cause a defect.
If the film thickness of the cellulose acylate film is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. Therefore, it is necessary to convert the sample of any film thickness to a standard of 80 μm. The conversion of the film thickness was determined as (80 μm-converted moisture permeability = measured moisture permeability × measured film thickness μm / 80 μm).
The measurement method of moisture permeability is “Polymer Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The cellulose acylate film sample 70 mmφ of the present invention was conditioned at 25 ° C., 90% RH, 60 ° C., and 95% RH for 24 hours, respectively, and a moisture permeation test apparatus (KK-709007) was applied. , Toyo Seiki Co., Ltd.) calculated the amount of water per unit area (g / m ² ) according to JIS Z-0208, and determined moisture permeability = mass after humidity adjustment−mass before humidity adjustment.

[Detection of front retardation before and after stretching, detection of slow axis]
A sample of 100 × 100 mm was prepared and stretched in the machine transport direction (MD direction) or the vertical direction (TD direction) under the condition of a temperature of 140 ° C. using a fixed uniaxial stretching machine. The front retardation of each sample before and after stretching was measured using an automatic birefringence meter KOBRA21ADH. The detection of the slow axis was determined from the orientation angle obtained during the retardation measurement. It is preferable that the change in Re by stretching is small, specifically, in-plane front retardation (nm) of a film in which Re (n) is stretched by n (%), in-plane of a film in which Re (0) is not stretched It is preferable that | Re (n) −Re (0) | /n≦1.0 when the front retardation (nm) is satisfied, and | Re (n) −Re (0) | / n ≦ 0. 3 is more preferably satisfied.

[Direction with slow axis]
When the cellulose acylate film of the present invention is used as a protective film for a polarizer, since the polarizer has an absorption axis in the machine transport direction (MD direction), the slow axis of the cellulose acylate film is near the MD direction or TD. Preferably there is. Light leakage and color change can be reduced by making the slow axis parallel or orthogonal to the polarizer. “Near” means that the slow axis and the MD or TD direction are in the range of 0 to 10 °, preferably 0 to 5 °.

[Evaluation Method for Cellulose Acylate Film of the Present Invention]
In evaluating the cellulose acylate film of the present invention, measurement was carried out by the following method.

(In-plane retardation Re, thickness direction retardation Rth)
A sample 30 mm × 40 mm was conditioned at 25 ° C. and 60% RH for 2 hours. Measurements were made by entering in the line direction. Also, Rth (λ) is the Re (λ) and incident light of wavelength λnm with the in-plane slow axis as the tilt axis and the film normal direction as 0 ° and the sample tilted to 50 ° every 10 ° KOBRA 21ADH is calculated based on the measured retardation value. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. The average refractive index of cellulose acylate is 1.48. The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness.

(Measurement of chromatic dispersion of Re and Rth)
A sample 30 mm × 40 mm was conditioned at 25 ° C. and 60% RH for 2 hours, and the wavelength was changed, and the same measurement was performed using an ellipsometer M-150 (manufactured by JASCO Corporation).

(Molecular orientation axis)
Phase difference when 70 mm × 100 mm sample is conditioned at 25 ° C. and 65% RH for 2 hours and the incident angle at normal incidence is changed with an automatic birefringence meter (KOBRA-21DH, Oji Scientific Co., Ltd.) From this, the molecular orientation axis was calculated.
(Axis misalignment)
The axis deviation angle was measured with an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments). Twenty points were measured at equal intervals over the entire width in the width direction, and the average absolute value was determined. The slow axis angle (axis deviation) range is measured at 20 points at equal intervals over the entire width direction, and the difference between the average of the absolute value of the axis deviation and the average of the four points from the smaller absolute value is taken. It is a thing.

[In-plane variation of retardation of cellulose acylate film]
The cellulose acylate film of the present invention preferably satisfies the following formula.
| Re _(MAX) −Re _(MIN) | ≦ 3 and | Rth _(MAX) −Rth _(MIN) | ≦ 5
[In the formula, Re _(MAX) and Rth _(MAX) are maximum retardation values of 1 m square film cut out arbitrarily, and Re _(MIN) and Rth _(MIN) are minimum values. ]

[Residual solvent amount of film]
It is preferable to dry on the conditions that the amount of residual solvents with respect to the cellulose acylate film of the present invention is in the range of 0.01 to 1.5% by mass. More preferably, it is 0.01-1.0 mass%. Curling can be suppressed by setting the residual solvent amount of the transparent support used in the present invention to 1.5% or less. More preferably, it is 1.0% or less. This is presumably because free deposition is reduced by reducing the amount of residual solvent during film formation by the above-described solvent casting method.

[surface treatment]
The cellulose acylate film can achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferred. Plasma-excitable gas refers to a gas that is plasma-excited under the above conditions, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail in pages 30 to 32 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention), and are preferably used in the present invention. be able to.

[Contact angle of film surface by alkali saponification]
Alkaline saponification is one effective means of surface treatment when the cellulose acylate film of the present invention is used as a transparent protective film for polarizing plates. In this case, the contact angle of the film surface after the alkali saponification treatment is preferably 55 ° or less. More preferably, it is 50 ° or less, and further preferably 45 ° or less. The contact angle evaluation method can be used as an evaluation of hydrophilicity / hydrophobicity by an ordinary method in which a water droplet having a diameter of 3 mm is dropped on the surface of the film after the alkali saponification treatment and the angle formed by the film surface and the water droplet is determined.

[Functional layer]
The cellulose acylate film of the present invention is applied to optical uses and photographic light-sensitive materials as its uses. In particular, the optical application is preferably a liquid crystal display device, and the liquid crystal display device has a liquid crystal cell in which liquid crystal is supported between two electrode substrates, two polarizing elements disposed on both sides thereof, and the liquid crystal It is more preferable that at least one optical compensation sheet is disposed between the cell and the polarizing element. As these liquid crystal display devices, TN, IPS, FLC, AFLC, OCB, STN, ECB, VA and HAN are preferable.
In that case, when using the cellulose acylate film of this invention for the above-mentioned optical use, providing various functional layers is implemented. These are, for example, an antistatic layer, a cured resin layer (transparent hard coat layer), an antireflection layer, an easy adhesion layer, an antiglare layer, an optical compensation layer, an alignment layer, a liquid crystal layer, and the like. These functional layers and materials for which the cellulose acylate film of the present invention can be used include surfactants, slipping agents, matting agents, antistatic layers, hard coat layers, etc. No. 2001-1745, published on March 15, 2001, Japan Institute of Invention) and described in detail on pages 32 to 45, and can be preferably used in the present invention.

[Optical film]
As described above, the optical film of the present invention is an optical film including a birefringent layer (a) and a transparent film (b), and the birefringent layer (a) is laminated on the transparent film (b). And satisfying all the conditions of the formulas (I) to (II).
In the present invention, the birefringent layer (a) needs to satisfy the formula (I). When the birefringent layer (a) of the optical film of the present invention satisfies 1 <(nx−nz) / (nx−ny), the birefringence in the thickness direction is larger than the birefringence in the film plane. Therefore, for example, the optical compensation of the liquid crystal cell is excellent. Moreover, it is preferably in the range of 1 <(nx−nz) / (nx−ny) ≦ 100. If the value is 100 or less, for example, when the optical film of the present invention is used in a liquid crystal display device, a sufficient contrast ratio can be obtained and the viewing angle characteristics are further improved. Further, since the value of (nx−nz) / (nx−ny) is excellent in optical compensation, for example, a range of 1 <(nx−nz) / (nx−ny) ≦ 80 is more preferable, and further preferable. Is 1 ≦ (nx−nz) / (nx−ny) ≦ 50. Further, when it is used for a vertical alignment (VA) mode liquid crystal display device, it is particularly preferable that 1 ≦ (nx−nz) / (nx−ny) ≦ 30.
In the schematic diagram of FIG. 1, the optical axis direction of the refractive index (nx, ny, nz) in the birefringent layer (a) 10 is indicated by an arrow. Refractive indexes nx, ny, and nz indicate the refractive indexes in the X-axis, Y-axis, and Z-axis directions, respectively, as described above. The Y axis is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis.

  Furthermore, in the present invention, the birefringent layer (a) needs to satisfy the condition of the formula (II). If Δn (a) is less than 0.0005, the optical film becomes thicker, and if it exceeds 0.5, it becomes difficult to control the phase difference of the optical film. The refractive index Δn (a) is more preferably 0.005 ≦ Δn (a) ≦ 0.2, and particularly preferably 0.02 ≦ Δn (a) ≦ 0.15.

  In the present invention, the thickness of the birefringent layer (a) is not particularly limited. However, the thickness of the liquid crystal display device can be reduced, and an optical film having an excellent viewing angle compensation function and a uniform retardation can be provided. The range of 0.1 to 50 μm is preferable, more preferably 0.5 to 30 μm, and still more preferably 1 to 20 μm. On the other hand, the thickness of the transparent film (b) can be appropriately determined according to the purpose of use and the like, but is preferably 5 to 500 μm, more preferably 10 to 200 μm, still more preferably from the viewpoint of strength and thinning. It is in the range of 15 to 150 μm.

  For example, the birefringent layer (a) may be laminated on one or both sides of the transparent film (b), and the number of laminated layers may be one or two or more. The transparent film (b) may be, for example, a single layer body or a laminate of two or more layers. When the transparent film (b) is a laminate, it may be composed of the same kind of polymer layer depending on the purpose, for example, improvement of strength, heat resistance, adhesion of the birefringent layer, etc. It may be a body.

  The material for forming the birefringent layer (a) is not particularly limited as long as it finally satisfies the above conditions of the present invention.

  As the forming material, for example, a non-liquid crystal material, particularly a non-liquid crystal polymer is preferable. Such a non-liquid crystalline material, for example, unlike a liquid crystalline material, forms a film exhibiting optical uniaxiality such as nx> nz and ny> nz depending on its own property, regardless of the orientation of the substrate. For this reason, for example, the substrate to be used is not limited to the alignment substrate. For example, even if it is an unaligned substrate, the step of applying the alignment film on the surface or the step of laminating the alignment film is omitted. can do.

  As the non-liquid crystalline polymer, for example, polymers such as polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide are preferable because they are excellent in heat resistance, chemical resistance, transparency, and rigidity. Any one of these polymers may be used alone, or a mixture of two or more having different functional groups such as a mixture of polyaryletherketone and polyamide may be used. . Among such polymers, polyimide is particularly preferable because of its high transparency, high orientation, and high stretchability.

  The molecular weight of the polymer is not particularly limited, but for example, the mass average molecular weight (Mw) is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 2,000 to 500,000. .

  As the polyimide, for example, a polyimide having high in-plane orientation and soluble in an organic solvent is preferable. Specifically, for example, it includes a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and an aromatic tetracarboxylic dianhydride disclosed in JP 2000-511296 A, and has the following general formula: A polymer containing one or more repeating units shown in (1) can be used.

General formula (1)

In the general formula (1), R ^{3 to} R ⁶ are hydrogen, halogen, phenyl group, 1 to 4 halogen atoms or C1 to 10 alkyl group (where “C1 to 10 alkyl group” It means at least one substituent selected from the group consisting of a phenyl group substituted with 1 to 10 alkyl groups, and the like, and a C1-10 alkyl group. Preferably, R ^{3 to} R ⁶ are at least one selected from the group consisting of halogen, a phenyl group, a phenyl group substituted with 1 to 4 halogen atoms or a C 1-10 alkyl group, and a C 1-10 alkyl group. Kinds of substituents.

  In the general formula (1), Z is, for example, a C6-20 tetravalent aromatic group, preferably a pyromellitic group, a polycyclic aromatic group, a derivative of a polycyclic aromatic group, or It is group represented by following General formula (2).

General formula (2)

In the general formula (2), Z ′ represents, for example, a covalent bond, C (R ⁷ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, or NR ^{There are 8} groups, and when there are multiple groups, they are the same or different. W represents an integer from 1 to 10. Each R ⁷ is independently hydrogen or C (R ⁹ ) ₃ . R ⁸ is hydrogen, an alkyl group having 1 to about 20 carbon atoms, or a C 6-20 aryl group, and in a plurality of cases, they are the same or different. R ⁹ are each independently hydrogen, fluorine or chlorine.

  Examples of the polycyclic aromatic group include a tetravalent group derived from naphthalene, fluorene, benzofluorene or anthracene. Examples of the substituted derivative of the polycyclic aromatic group include a C1-10 alkyl group, a fluorinated derivative thereof, and at least one group selected from the group consisting of halogens such as F and Cl. And the above polycyclic aromatic group.

  In addition, for example, a homopolymer described in JP-A-8-511812, wherein the repeating unit is represented by the following general formula (3) or (4), or the repeating unit is represented by the following general formula (5): The polyimide etc. which are shown are mentioned. In addition, the polyimide of the following general formula (5) is a preferable form of the homopolymer of the following formula (3).

General formula (3)

General formula (4)

General formula (5)

In general formulas (3) to (5), G and G ′ are, for example, a covalent bond, a CH ₂ group, a C (CH ₃ ) ₂ group, a C (CF ₃ ) ₂ group, a C (CX ₃ ) ₂ group ( Here, X is halogen.), Each independently from the group consisting of CO group, O atom, S atom, SO ₂ group, Si (CH ₂ CH ₃ ) ₂ group, and N (CH ₃ ) group Each of which may be the same or different.

  In general formula (3) and general formula (5), L is a substituent, and d and e represent the number of substitutions thereof. L is, for example, a halogen, a C1-3 alkyl group, a C1-3 halogenated alkyl group, a phenyl group, or a substituted phenyl group, and in a plurality of cases, they are the same or different. Examples of the substituted phenyl group include substituted phenyl groups having at least one type of substituent selected from the group consisting of halogen, C1-3 alkyl groups, and C1-3 halogenated alkyl groups. Examples of the halogen include fluorine, chlorine, bromine, and iodine. d is an integer from 0 to 2, and e is an integer from 0 to 3.

  In general formulas (3) to (5), Q is a substituent, and f represents the number of substitutions. Q is, for example, selected from the group consisting of hydrogen, halogen, alkyl group, substituted alkyl group, nitro group, cyano group, thioalkyl group, alkoxy group, aryl group, substituted aryl group, alkyl ester group, and substituted alkyl ester group And when Q is plural, they are the same or different. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted alkyl group include a halogenated alkyl group. Examples of the substituted aryl group include a halogenated aryl group. f is an integer from 0 to 4, and g and h are integers from 0 to 3 and 1 to 3, respectively. Further, g and h are preferably larger than 1.

In the general formula (4), R ¹⁰ and R ¹¹ are groups independently selected from the group consisting of hydrogen, halogen, phenyl group, substituted phenyl group, alkyl group, and substituted alkyl group. Among these, R ¹⁰ and R ¹¹ are preferably each independently a halogenated alkyl group.

In the general formula (5), M ¹ and M ² are the same or different and are, for example, halogen, C1-3 alkyl group, C1-3 halogenated alkyl group, phenyl group, or substituted phenyl group. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted phenyl group include substituted phenyl groups having at least one type of substituent selected from the group consisting of halogen, C1-3 alkyl groups, and C1-3 halogenated alkyl groups.

  Specific examples of the polyimide represented by the general formula (3) include those represented by the following formula (6).

Furthermore, examples of the polyimide include a copolymer obtained by appropriately copolymerizing an acid dianhydride other than the skeleton (repeating unit) as described above and a diamine.
As an acid dianhydride, aromatic tetracarboxylic dianhydride is mentioned, for example. Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, heterocyclic aromatic tetracarboxylic dianhydride, 2, And 2'-substituted biphenyltetracarboxylic dianhydride.

  Examples of pyromellitic dianhydride include pyromellitic dianhydride, 3,6-diphenylpyromellitic dianhydride, 3,6-bis (trifluoromethyl) pyromellitic dianhydride, 3,6-dibromopyro Examples include mellitic dianhydride and 3,6-dichloropyromellitic dianhydride. Examples of the benzophenone tetracarboxylic dianhydride include 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,3,3 ′, 4′-benzophenone tetracarboxylic dianhydride, 2 , 2 ′, 3,3′-benzophenone tetracarboxylic dianhydride and the like. Examples of the naphthalenetetracarboxylic dianhydride include 2,3,6,7-naphthalene-tetracarboxylic dianhydride, 1,2,5,6-naphthalene-tetracarboxylic dianhydride, 2,6 -Dichloro-naphthalene-1,4,5,8-tetracarboxylic dianhydride and the like. Examples of the heterocyclic aromatic tetracarboxylic dianhydride include thiophene-2,3,4,5-tetracarboxylic dianhydride and pyrazine-2,3,5,6-tetracarboxylic dianhydride. Pyridine-2,3,5,6-tetracarboxylic dianhydride and the like. Examples of the 2,2′-substituted biphenyltetracarboxylic dianhydride include 2,2′-dibromo-4,4 ′, 5,5′-biphenyltetracarboxylic dianhydride and 2,2′-dichloro. -4,4 ', 5,5'-biphenyltetracarboxylic dianhydride, 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride, etc. Can be mentioned.

  Other examples of the aromatic tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and bis (2,3-dicarboxyphenyl) methane dianhydride. Bis (2,5,6-trifluoro-3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3 3-hexafluoropropane dianhydride, 4,4 ′-(3,4-dicarboxyphenyl) -2,2-diphenylpropane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 4 , 4′-oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfonic dianhydride (3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride), 4,4 ′ -[4,4'-I Propylidene-di (p-phenyleneoxy)] bis (phthalic anhydride), N, N- (3,4-dicarboxyphenyl) -N-methylamine dianhydride, bis (3,4-dicarboxyphenyl) Examples include diethylsilane dianhydride.

  Among these, the aromatic tetracarboxylic dianhydride is preferably 2,2′-substituted biphenyltetracarboxylic dianhydride, more preferably 2,2′-bis (trihalomethyl) -4,4. ', 5,5'-biphenyltetracarboxylic dianhydride, more preferably 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride It is.

  Examples of the diamine include aromatic diamines, and specific examples include benzene diamine, diaminobenzophenone, naphthalene diamine, heterocyclic aromatic diamine, and other aromatic diamines.

  Examples of benzenediamine include o-, m- and p-phenylenediamine, 2,4-diaminotoluene, 1,4-diamino-2-methoxybenzene, 1,4-diamino-2-phenylbenzene and 1,3. -A diamine selected from the group consisting of benzenediamines such as diamino-4-chlorobenzene. Examples of the diaminobenzophenone include 2,2'-diaminobenzophenone and 3,3'-diaminobenzophenone. Examples of the naphthalenediamine include 1,8-diaminonaphthalene and 1,5-diaminonaphthalene. Examples of the heterocyclic aromatic diamine include 2,6-diaminopyridine, 2,4-diaminopyridine, and 2,4-diamino-S-triazine.

  In addition to these, the aromatic diamine includes 4,4′-diaminobiphenyl, 4,4′-diaminodiphenylmethane, 4,4 ′-(9-fluorenylidene) -dianiline, 2,2′-bis ( Trifluoromethyl) -4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 2,2′-dichloro-4,4′-diaminobiphenyl, 2,2 ′, 5 5′-tetrachlorobenzidine, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) -1,1, 1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 1,3-bis (3-aminophen Xyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3 , 3,3-hexafluoropropane, 4,4′-diaminodiphenylthioether, 4,4′-diaminodiphenylsulfone, and the like.

  Examples of the polyetherketone that is a material for forming the birefringent layer (a) include polyaryletherketone described in JP-A No. 2001-49110 and represented by the following general formula (7).

General formula (7)

In general formula (7), X represents a substituent, and q represents the number of substitutions. X is, for example, a halogen atom, a lower alkyl group, a halogenated alkyl group, a lower alkoxy group, or a halogenated alkoxy group, and when there are a plurality of X, they are the same or different.
Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom, and among these, a fluorine atom is preferable. The lower alkyl group is, for example, preferably a C1-6 linear or branched lower alkyl group, more preferably a C1-4 linear or branched alkyl group. Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group are preferable, and a methyl group and an ethyl group are particularly preferable. Examples of the halogenated alkyl group include halides of the lower alkyl group such as a trifluoromethyl group. As the lower alkoxy group, for example, a C1-6 linear or branched alkoxy group is preferable, and a C1-4 linear or branched alkoxy group is more preferable. Specifically, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group are more preferable, and a methoxy group and an ethoxy group are particularly preferable. . Examples of the halogenated alkoxy group include halides of the lower alkoxy group such as a trifluoromethoxy group.

In the general formula (7), q is an integer from 0 to 4. In the general formula (7), it is preferable that q = 0 and that the carbonyl group bonded to both ends of the benzene ring and the oxygen atom of the ether are present in the para position.
In the general formula (7), R ¹ is a group represented by the following formula (8), and m is an integer of 0 or 1.

Formula (8)

In the formula (8), X ′ represents a substituent, and is the same as X in the general formula (7), for example. In Formula (8), when there are a plurality of X ′, they are the same or different. q ′ represents the number of substitutions of X ′, and is an integer from 0 to 4, preferably q ′ = 0. P is an integer of 0 or 1.
In formula (8), R ² represents a divalent aromatic group. Examples of the divalent aromatic group include an o-, m- or p-phenylene group, or naphthalene, biphenyl, anthracene, o-, m- or p-terphenyl, phenanthrene, dibenzofuran, biphenyl ether, or And divalent groups derived from biphenylsulfone. In these divalent aromatic groups, hydrogen directly bonded to the aromatic group may be substituted with a halogen atom, a lower alkyl group or a lower alkoxy group. Among these, R ² is preferably an aromatic group selected from the group consisting of the following formulas (9) to (15).

In the formula (7), the R ¹ is preferably a group represented by the following formula (16). In the following formula (16), R ² and p are as defined in the formula (8).

Formula (16)

Furthermore, in said Formula (7), n represents a polymerization degree, for example, is the range of 2-5000, Preferably, it is the range of 5-500. Further, the polymerization may be composed of repeating units having the same structure, or may be composed of repeating units having different structures. In the latter case, the polymerization mode of the repeating unit may be block polymerization or random polymerization.
Furthermore, the end of the polyaryl ether ketone represented by the formula (7) is preferably fluorine on the p-tetrafluorobenzoylene group side and a hydrogen atom on the oxyalkylene group side. For example, it can be represented by the following general formula (17). In the following formula, n represents the same degree of polymerization as in formula (7).

  Specific examples of the polyaryl ether ketone represented by the general formula (7) include those represented by the following formulas (18) to (21). In each of the following formulas, n represents the general formula (7). Represents the same degree of polymerization.

  In addition to these, examples of the polyamide or polyester that is a material for forming the birefringent layer (a) include polyamides and polyesters described in JP-T-10-508048. The unit can be represented by the following general formula (22), for example.

General formula (22)

In general formula (22), Y is O or NH. E is, for example, a covalent bond, a C2 alkylene group, a halogenated C2 alkylene group, a CH ₂ group, a C (CX ₃ ) ₂ group (where X is a halogen or hydrogen), a CO group, and an O atom. , S atom, SO ₂ group, Si (R) ₂ group, and N (R) group, which may be the same or different from each other. In E, R is at least one of a C1-3 alkyl group and a C1-3 halogenated alkyl group, and is in a meta position or a para position with respect to a carbonyl functional group or a Y group.
Moreover, in General formula (22), A and A 'are substituents and t and z represent the number of each substitution. P is an integer from 0 to 3, q is an integer from 1 to 3, and r is an integer from 0 to 3.
The A is, for example, hydrogen, halogen, C1-3 alkyl group, C1-3 halogenated alkyl group, an alkoxy group represented by OR (where R is as defined above), an aryl group, Substituted aryl groups by halogenation, etc., C1-9 alkoxycarbonyl groups, C1-9 alkylcarbonyloxy groups, C1-12 aryloxycarbonyl groups, C1-12 arylcarbonyloxy groups and substituted derivatives thereof, C1-12 arylcarbamoyl groups, And selected from the group consisting of a C1-12 arylcarbonylamino group and substituted derivatives thereof, and in a plurality of cases, they are the same or different. Said A 'is selected from the group which consists of a halogen, a C1-3 alkyl group, a C1-3 halogenated alkyl group, a phenyl group, and a substituted phenyl group, for example, and when it exists, it is the same or different, respectively. Examples of the substituent on the phenyl ring of the substituted phenyl group include halogen, C1-3 alkyl group, C1-3 halogenated alkyl group, and combinations thereof. t is an integer from 0 to 4, and z is an integer from 0 to 3.
Among the repeating units of polyamide or polyester represented by the general formula (22), those represented by the following general formula (23) are preferable.

Formula (23)

  In the general formula (23), A, A ′ and Y are those defined in the general formula (22), and v is an integer of 0 to 3, preferably 0 to 2. x and y are each 0 or 1, but are not 0 at the same time.

Below, the manufacturing method of the optical film of this invention is demonstrated. As long as the optical film of the present invention satisfies the conditions (I) and (II), its production method is not particularly limited. For example, the following first production method and second production method are provided. Is mentioned.
In the first production method, a coating film is formed by directly applying a material for forming a birefringent layer on a transparent substrate that exhibits shrinkage in one direction in the plane. This is a method of contracting the membrane. By such a method, the contracted transparent substrate becomes a transparent film (b), the contracted coating film becomes a birefringent layer (a), and the birefringent layer (a) is directly on the transparent film (b). A fixed optical film of the present invention is obtained. Thus, the optical film of the present invention in which the birefringent layer (a) is directly laminated on the transparent film (b) and satisfies all the conditions (I) and (II) is, for example, a transparent film as in the prior art. The upper birefringent layer need not be used after being transferred to another substrate, and can be used as it is as a visual compensation film or the like. The contractility of the substrate can be imparted, for example, by subjecting the substrate to a heat treatment in advance.

  According to this method, first, a non-liquid crystal polymer such as polyimide exhibits an optical property of nx = ny> nz regardless of whether or not the transparent substrate is aligned. The film exhibits optical uniaxiality. That is, the phase difference is shown only in the thickness direction. Since the coating film on the transparent substrate also shrinks in the plane direction due to the shrinkability of the transparent substrate, the coating film further has a refractive difference in the plane, resulting in optical biaxiality (nx> ny> nz). ).

  Thus, since the non-liquid crystal polymer has the property of exhibiting optical uniaxiality, it is not necessary to use the orientation of the substrate. For this reason, both an oriented substrate and a non-oriented substrate can be used as a transparent substrate. Further, for example, a phase difference due to birefringence may be generated, or a phase difference due to birefringence may not be generated. Examples of the transparent substrate that generates a phase difference due to birefringence include a stretched film and the like, and those having a controlled refractive index in the thickness direction can also be used. The refractive index can be controlled, for example, by a method in which a polymer film is bonded to a heat-shrinkable film and then heated and stretched.

  The transparent substrate is preferably stretched in any one direction within the surface, for example, in order to have shrinkage in one direction within the surface. In this way, by stretching in advance, a contraction force is generated in the direction opposite to the stretching direction. By utilizing the in-plane shrinkage difference of the transparent substrate, an in-plane refractive index difference is imparted to the non-liquid crystal material of the coating film. Specific conditions are shown below.

  The thickness of the transparent substrate before stretching is not particularly limited, but is, for example, in the range of 10 to 200 μm, preferably in the range of 20 to 150 μm, and particularly preferably in the range of 30 to 100 μm. The stretching ratio is not particularly limited as long as the birefringent layer formed on the stretched transparent substrate exhibits optical biaxiality (nx> ny> nz).

  The method for coating the material for forming the birefringent layer on the transparent substrate is not particularly limited. For example, a method for heating and melting the non-liquid crystalline polymer as described above or a method for coating the non-liquid crystalline polymer with a solvent. And a method of coating a polymer solution dissolved in Among them, a method of applying a polymer solution is preferable because of excellent workability.

  Although the polymer concentration in the polymer solution is not particularly limited, for example, since the viscosity becomes easy to apply, for example, it is preferably 5 to 50 parts by mass of the non-liquid crystalline polymer with respect to 100 parts by mass of the solvent. Preferably it is 10-40 mass parts.

  The solvent of the polymer solution is not particularly limited as long as a forming material such as a non-liquid crystalline polymer can be dissolved, and can be appropriately determined according to the type of the forming material. Specific examples include, for example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene; phenols such as phenol and parachlorophenol; benzene, toluene, Aromatic hydrocarbons such as xylene, methoxybenzene, 1,2-dimethoxybenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N-methyl-2-pyrrolidone; Ester solvents such as ethyl acetate and butyl acetate; t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, die Alcohol solvents such as lenglycol dimethyl ether, propylene glycol, dipropylene glycol and 2-methyl-2,4-pentanediol; amide solvents such as dimethylformamide and dimethylacetamide; nitrile solvents such as acetonitrile and butyronitrile; Examples include ether solvents such as diethyl ether, dibutyl ether and tetrahydrofuran; carbon disulfide, ethyl cellosolve, butyl cellosolve and the like. One type of these solvents may be used, or two or more types may be used in combination.

For example, the polymer solution may further contain various additives such as a stabilizer, a plasticizer, and metals as required.
In addition, the polymer solution may contain other different resins as long as the orientation of the forming material is not significantly reduced. Examples of other resins include various general-purpose resins, engineering plastics, thermoplastic resins, and thermosetting resins.

  Examples of the general-purpose resin include polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), ABS resin, and AS resin. Examples of the engineering plastic include polyacetate (POM), polycarbonate (PC), polyamide (PA: nylon), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). Examples of the thermoplastic resin include polyphenylene sulfide (PPS), polyethersulfone (PES), polyketone (PK), polyimide (PI), polycyclohexanedimethanol terephthalate (PCT), polyarylate (PAR), and liquid crystal polymer ( LCP) and the like. Examples of the thermosetting resin include an epoxy resin and a phenol novolac resin.

  Thus, when mix | blending other resin etc. with the said polymer solution, the compounding quantity is 0-50 mass% with respect to a polymer material, for example, Preferably, it is 0-30 mass%. .

  Examples of the polymer solution coating method include spin coating, roll coating, flow coating, printing, dip coating, cast film formation, bar coating, and gravure printing. Moreover, in the case of coating, the superposition | polymerization method of a polymer layer is also employable as needed.

  And a transparent substrate is contracted by heat-processing to the coating film on a transparent substrate. The birefringent layer (a) is formed by shrinking the coating film as the transparent substrate shrinks. The conditions for the heat treatment are not particularly limited and can be appropriately determined depending on, for example, the type of material of the transparent substrate. For example, the heating temperature is in the range of 25 to 300 ° C, and preferably in the range of 50 to 200 ° C. Especially preferably, it is the range of 60-180 degreeC.

  After the heat treatment, the solvent of the polymer solution remaining in the birefringent layer (a) may change the optical properties of the optical film over time in proportion to the amount thereof. 5% or less is preferable, More preferably, it is 2% or less, More preferably, it is 0.2% or less.

  On the other hand, the second manufacturing method is a method in which a material for forming a birefringent layer is directly coated on a transparent substrate to form a coating film, and the transparent substrate and the coating film are stretched together. By such a method, the stretched transparent substrate becomes a transparent film (b), the similarly stretched coating film becomes a birefringent layer (a), and the birefringent layer (a) is formed on the transparent film (b). The optical film of the present invention directly immobilized is obtained. This optical film also has the same effect as the optical film obtained by the first manufacturing method. In this production method, the material for forming the birefringent layer (a) can be applied in the same manner as in the first production method.

  According to this method, as in the first manufacturing method, a non-liquid crystal polymer such as polyimide exhibits optical characteristics of nx = ny> nz regardless of the orientation of the transparent substrate due to its properties. A coating film formed from a polymer exhibits optical uniaxiality. And by extending | stretching together the laminated body of a transparent substrate and a coating film to one direction in a surface, a coating film produces a refraction difference in a surface further, and optical biaxiality (nx> ny> nz). It comes to show.

  The stretching method of the laminate of the transparent substrate and the coating film is not particularly limited, but for example, free end longitudinal stretching that is uniaxially stretched in the longitudinal direction, fixed end that is uniaxially stretched in the width direction in a state where the longitudinal direction of the film is fixed Examples of the method include sequential stretching and simultaneous biaxial stretching in which stretching is performed in both the transverse direction, the longitudinal direction, and the width direction.

  And although extending | stretching of a laminated body may be performed, for example by pulling both a transparent substrate and a coating film together, it is preferable to extend | stretch only a transparent substrate from the following reasons. When only the transparent substrate is stretched, the coating film on the transparent substrate is indirectly stretched by the tension generated in the transparent substrate by this stretching. And, since stretching a single layer body is usually a uniform stretching rather than stretching a laminate, if only a transparent substrate is stretched uniformly as described above, along with this, on the transparent substrate This is because the coated film can also be stretched uniformly.

  The stretching conditions are not particularly limited, and can be appropriately determined according to, for example, the type of material for forming the transparent substrate or the birefringent layer. As a specific example, the draw ratio is preferably greater than 1 and not greater than 5 times, more preferably greater than 1 and not greater than 4 times, and particularly preferably greater than 1 and not greater than 3 times.

  Even in the case of manufacturing an optical film by the second manufacturing method, for example, the condition (I) can be obtained by selecting the forming material of the transparent substrate and the forming material of the birefringent layer (a) as described above. Can be met.

  In addition to the first and second production methods, the method for producing the optical film of the present invention includes, for example, a material for forming the birefringent layer (a) on a transparent substrate in which stress is applied in one direction in the plane. There is a method of thinning.

  In addition to this, for example, a method of thinning the forming material on the transparent film (b) by blowing wind or the like from one direction, the forming material on the transparent film (b) having anisotropy There are methods such as coating.

The characteristics of the optical film were evaluated by the following methods.
(Measurement of phase difference value Δnd, orientation axis accuracy)
It measured using the phase difference meter (The Oji Scientific Instruments company make, brand name KOBRA21ADH).

(Measurement of refractive index)
The refractive index at 590 nm was measured using a trade name KOBRA21ADH manufactured by Oji Scientific Instruments.

(Film thickness measurement)
Measurement was performed using an Anritsu brand name digital micrometer K-351C type.

[Humidity dependency of Re and Rth of optical film]
In the optical film of the present invention, both the in-plane retardation Re and the retardation Rth in the film thickness direction preferably have small changes due to humidity. Specifically, the difference ΔRe (= Re 10% RH−Re 80% RH) between the Re value at 25 ° C. and 10% RH and the Re value at 25 ° C. and 80% RH is preferably 0 to 20 nm. More preferably, it is 0-15 nm, More preferably, it is 0-10 nm.
Also, the Rth value difference ΔRth (= Rth 10% RH−Rth 80% RH) is preferably 0 to 50 nm, more preferably 0 to 40 nm, and still more preferably 0 to 30 nm.
This can be achieved by improving the humidity dependency of the cellulose acylate film to be used.
Furthermore, when using an optical film for a liquid crystal display device, as a compulsory evaluation for long-term use, a wet heat thermostat is often performed, but until now, after the thermo is taken out, uneven unevenness occurs in the panel screen. There were many. However, it has been found that when the optical film of the present invention in which the in-plane retardation Re and the retardation Rth in the film thickness direction are small due to humidity is used, unevenness does not occur even after taking out the thermo. This is presumably because the change in Re and Rth of the optical film is small even when there is a humidity change in the thermo and before and after.

(Measurement of chromatic dispersion of Re and Rth)
Similar to the cellulose acylate film, wavelength dispersion of Re and Rth was measured.
| Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35
It is preferable that
Furthermore, | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 8 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 30
It is preferable that
[Wherein, Re ₍ λ ₎ is a front retardation value (unit: nm) at a wavelength λnm, and Rth ₍ λ ₎ is a retardation value (unit: nm) in a film thickness direction at a wavelength λnm. ]
This can be achieved by controlling the wavelength dispersion of the cellulose acylate film used.
As described above, when a panel using an optical film is subjected to wet heat, the color of the panel screen may have changed after the thermo is taken out. However, when the optical film with controlled wavelength dispersion of the present invention is used, the color change does not occur even after the thermo is taken out.

[In-plane variation of retardation of optical film]
The optical film of the present invention preferably satisfies the following formula.
| Re _(MAX) −Re _(MIN) | ≦ 3 and | Rth _(MAX) −Rth _(MIN) | ≦ 5
More preferably,
| Re _(MAX) −Re _(MIN) | ≦ 2 and | Rth _(MAX) −Rth _(MIN) | ≦ 4
It is preferable that
[In the formula, Re _(MAX) and Rth _(MAX) − are the maximum retardation values of 1 m square film cut out arbitrarily, and Re _(MIN) and Rth _(MIN) are the minimum values. ]
This can also be achieved by reducing the in-plane variation in retardation of the cellulose acylate film to be used.

  The optical film of the present invention preferably further has at least one of an adhesive layer and a pressure-sensitive adhesive layer. This is because adhesion between the optical film of the present invention and other members such as other optical layers and liquid crystal cells can be facilitated, and peeling of the optical film of the present invention can be prevented. Therefore, the adhesive layer and the pressure-sensitive adhesive layer are preferably laminated on the outermost layer of the optical film, and may be one outermost layer of the optical film or may be laminated on both outermost layers.

  The material of the adhesive layer is not particularly limited. For example, an acrylic, vinyl alcohol, silicone, polyester, polyurethane, polyether, or other polymer pressure sensitive adhesive, rubber pressure sensitive adhesive, etc. Can be used. Alternatively, these materials may contain fine particles to form a layer exhibiting light diffusibility. Among these, for example, a material excellent in hygroscopicity and heat resistance is preferable. With such a property, for example, when used in a liquid crystal display device, it can prevent foaming and peeling due to moisture absorption, deterioration of optical characteristics due to a difference in thermal expansion, warpage of the liquid crystal cell, etc., and high quality and durability. The display device is also excellent.

  As described above, the optical film of the present invention may be used alone, or may be used in various optical applications as a laminate in combination with other optical members as necessary. Specifically, it is useful as an optical compensation member, particularly as a visual compensation member. Although it does not restrict | limit especially as another optical member, For example, the polarizer etc. which are shown below are mentioned.

The polarizing plate of the present invention is a laminated polarizing plate including an optical film and a polarizer, and the optical film is the optical film of the present invention.
The configuration of such a polarizing plate is not particularly limited as long as it has the optical film of the present invention, and examples thereof include those shown in FIG. 2 or FIG. 2 and 3 are cross-sectional views showing examples of the laminated polarizing plate of the present invention, and the same reference numerals are given to the same parts in both figures. In addition, the polarizing plate of this invention is not limited to the following structures, Furthermore, the other optical member etc. may be included.

  The laminated polarizing plate 20 shown in FIG. 2 has the optical film 1, the polarizer 2 and the two transparent protective layers 3 of the present invention, and the transparent protective layers 3 are laminated on both surfaces of the polarizer 2, respectively. An optical film 1 is further laminated on the transparent protective layer 3. In addition, since the optical film 1 is a laminated body of a birefringent layer (a) and a transparent film (b) as described above, any surface may face the transparent protective layer 3.

  In addition, a transparent protective layer may be laminated | stacked on both sides of a polarizer as shown in the figure, and may be laminated | stacked only on either one surface. Moreover, when laminating | stacking on both surfaces, the same kind of transparent protective layer may be used, for example, and a different kind of transparent protective layer may be used.

On the other hand, the laminated polarizing plate 30 shown in FIG. 3 has the optical film 1, the polarizer 2 and the transparent protective layer 3 of the present invention, and the optical film 1 and the transparent protective layer 3 are laminated on both sides of the polarizer 2, respectively. Yes.
And since the optical film 1 is a laminated body of a birefringent layer (a) and a transparent film (b) as mentioned above, any surface may face a polarizer, For example, as follows For this reason, it is preferable to dispose the optical film 1 so that the transparent film (b) side faces the polarizer 2. This is because the transparent film (b) of the optical film 1 can also be used as a transparent protective layer in the laminated polarizing plate with such a configuration. That is, instead of laminating a transparent protective layer on both sides of the polarizer, a transparent protective layer is laminated on one side of the polarizer, and an optical film is laminated on the other side so that the transparent film faces Thus, the transparent film also serves as the other transparent protective layer of the polarizer. For this reason, the polarizing plate made still thinner can be obtained.

The polarizer is not particularly limited, and is prepared, for example, by adsorbing and dying dichroic substances such as iodine and dichroic dyes on various films, crosslinking, stretching and drying by a conventionally known method. Can be used. Among these, a film that transmits linearly polarized light when natural light is incident is preferable, and a film that is excellent in light transmittance and degree of polarization is preferable.
Examples of various films that adsorb dichroic substances include hydrophilic polymers such as polyvinyl alcohol (PVA) films, partially formalized PVA films, ethylene / vinyl acetate copolymer partially saponified films, and cellulose films. In addition to these, for example, polyene oriented films such as PVA dehydrated products and polyvinyl chloride dehydrochlorinated products can also be used. Among these, PVA film is preferable. Moreover, although the thickness of a polarizing film is the range of 1-80 micrometers normally, it is not limited to this.

  The protective layer is not particularly limited and a conventionally known transparent film can be used. For example, a protective layer having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferable. Specific examples of the material for such a transparent protective layer include cellulose resins such as triacetyl cellulose, polyester, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, and polynorbornene. And transparent resins such as those based on polyolefin, polyolefin, acrylic and acetate. In addition, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins are also included. Among these, a TAC film whose surface is saponified with alkali or the like is preferable from the viewpoint of polarization characteristics and durability.

  Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) is mentioned. Examples of the polymer material include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylenemaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film may be, for example, an extruded product of a resin composition.

In the present invention, at least one of the polarizing plate protective layers is preferably the cellulose acylate of the present invention.
Moreover, it is preferable that a protective layer does not have coloring, for example. Specifically, the retardation value (Rth) in the film thickness direction represented by the following formula is preferably in the range of −90 nm to +75 nm, more preferably −80 nm to +60 nm, and particularly preferably −70 nm. It is in the range of ˜ + 45 nm. When the retardation value is in the range of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate due to the protective film can be sufficiently eliminated. In the following formula, nx, ny, and nz are the same as described above, and d indicates the film thickness.
Rth = [(nx + ny) / 2−nz] · d

  The transparent protective layer may further have an optical compensation function. As described above, the transparent protective layer having an optical compensation function is intended to prevent coloring or increase the viewing angle for good viewing caused by a change in viewing angle based on a phase difference in a liquid crystal cell, for example. A well-known thing can be used. Specifically, for example, various stretched films obtained by uniaxially or biaxially stretching the transparent resin described above, alignment films such as liquid crystal polymers, and laminates in which alignment layers such as liquid crystal polymers are arranged on a transparent substrate are exemplified. It is done. Among these, a liquid crystal polymer alignment film is preferable because a wide viewing angle with good visual recognition can be achieved, and in particular, the optical compensation layer composed of a discotic or nematic liquid crystal polymer inclined alignment layer is used. An optical compensation retardation plate supported by an acetylcellulose film or the like is preferable. Examples of such an optical compensation retardation plate include commercially available products such as “WV film” manufactured by Fuji Photo Film Co., Ltd. The optical compensation phase difference plate may be one in which optical properties such as phase difference are controlled by laminating two or more film supports such as a phase difference film and a triacetyl cellulose film.

  The thickness of the transparent protective layer is not particularly limited, and can be appropriately determined according to, for example, the phase difference or the protective strength, but is usually 500 μm or less, preferably 5 to 300 μm, more preferably 5 to 150 μm. is there.

The transparent protective layer can be appropriately formed by a conventionally known method such as a method of applying various transparent resins to a polarizing film, a method of laminating a transparent resin film or an optical compensation phase difference plate on the polarizing film, or a commercially available product. Can also be used.
Further, the transparent protective layer may be further subjected to, for example, a hard coat treatment, an antireflection treatment, a treatment for the purpose of preventing or diffusing sticking, anti-glare and the like. The hard coat treatment is for the purpose of preventing scratches on the polarizing plate surface, for example, a treatment for forming a cured film having excellent hardness and slipperiness composed of a curable resin on the surface of the transparent protective layer. . As the curable resin, for example, an ultraviolet curable resin such as silicone, urethane, acryl, and epoxy can be used, and the treatment can be performed by a conventionally known method. The purpose of preventing sticking is to prevent adhesion between adjacent layers. The antireflection treatment is intended to prevent reflection of external light on the surface of the polarizing plate, and can be performed by forming a conventionally known antireflection layer or the like.

  The anti-glare treatment is intended to prevent visual interference of light transmitted through the polarizing plate due to reflection of external light on the surface of the polarizing plate. For example, the anti-glare treatment can be applied to the surface of the transparent protective layer by a conventionally known method. This can be done by forming an uneven structure. Examples of a method for forming such a concavo-convex structure include a surface roughening method by sandblasting or embossing, a method of forming a transparent protective layer by blending transparent fine particles into the transparent resin as described above, and the like. .

  Examples of the transparent fine particles include silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like. In addition, inorganic fine particles having conductivity, crosslinked or uncrosslinked polymer, and the like. Organic fine particles composed of granular materials or the like can also be used. The average particle diameter of the transparent fine particles is not particularly limited, but is, for example, in the range of 0.5 to 20 μm. Further, the blending ratio of the transparent fine particles is not particularly limited, but in general, the range of 2 to 70 parts by mass, more preferably 5 to 50 parts by mass, per 100 parts by mass of the transparent resin as described above.

  The antiglare layer containing the transparent fine particles can be used as, for example, the transparent protective layer itself, or may be formed as a coating layer on the surface of the transparent protective layer. Furthermore, the anti-glare layer may also serve as a diffusion layer (visual compensation function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, anti-sticking layer, diffusion layer, antiglare layer, etc. are laminated on the polarizing plate separately from the transparent protective layer, for example, as an optical layer composed of a sheet provided with these layers. Also good.

The method for laminating the constituent layers (optical film, polarizer, transparent protective layer, etc.) is not particularly limited, and can be performed by a conventionally known method. In general, the same pressure-sensitive adhesives and adhesives as described above can be used, and the type thereof can be appropriately determined depending on the material of each component. Examples of the adhesive include polymer adhesives such as acrylic, vinyl alcohol, silicone, polyester, polyurethane, and polyether, and rubber adhesives. Further, an adhesive composed of a water-soluble crosslinking agent of vinyl alcohol polymers such as glutaraldehyde, melamine and oxalic acid can be used. The pressure-sensitive adhesives and adhesives as described above are hardly peeled off due to, for example, the influence of humidity and heat, and are excellent in light transmittance and degree of polarization. Specifically, when the polarizer is a PVA-based film, for example, a PVA-based adhesive is preferable from the viewpoint of the stability of the adhesion treatment. For example, these adhesives and pressure-sensitive adhesives may be directly applied to the surface of the polarizer or the transparent protective layer, or a layer such as a tape or sheet composed of the adhesive or pressure-sensitive adhesive is arranged on the surface. Also good. For example, when prepared as an aqueous solution, other additives and catalysts such as acids may be blended as necessary. In addition, when apply | coating an adhesive agent, you may mix | blend another additive and catalysts, such as an acid, further with adhesive agent aqueous solution, for example. The thickness of such an adhesive layer is not particularly limited, but is, for example, 1 nm to 500 nm, preferably 10 nm to 300 nm, and more preferably 20 nm to 100 nm. The method is not particularly limited, and for example, a conventionally known method using an adhesive such as an acrylic polymer or a vinyl alcohol polymer can be employed. In addition, an adhesive containing a water-soluble cross-linking agent of PVA polymer such as glutaraldehyde, melamine, oxalic acid and the like can be obtained because it can form a polarizing plate that is hardly peeled off by humidity, heat, etc. and has excellent light transmittance and polarization degree. preferable. These adhesives can be used, for example, by applying the aqueous solution to the surface of each component and drying.
In the aqueous solution, for example, other additives and a catalyst such as an acid can be blended as necessary. Among these, as the adhesive, a PVA adhesive is preferable from the viewpoint of excellent adhesiveness with the PVA film.

  In addition to the polarizer as described above, the optical film of the present invention can be used in combination with conventionally known optical members such as various retardation plates, diffusion control films, brightness enhancement films, and the like. Examples of the retardation plate include a uniaxially or biaxially stretched polymer film, a Z-axis aligned treatment, a liquid crystalline polymer coating film, and the like. Examples of the diffusion control film include films utilizing diffusion, scattering, and refraction, and these can be used for, for example, control of viewing angle, glare related to resolution, and control of scattered light. As the brightness enhancement film, for example, a brightness enhancement film using selective reflection of cholesteric liquid crystal and a quarter wavelength plate (λ / 4 plate), a scattering film using anisotropic scattering by the polarization direction, and the like can be used. . Moreover, an optical film can also be combined with a wire grid type polarizer, for example.

  In practical use, the laminated polarizing plate of the present invention may further contain other optical layers in addition to the optical film of the present invention. As an optical layer, conventionally well-known various optical layers used for formation of a liquid crystal display device etc., such as a polarizing plate, a reflecting plate, a transflective plate, a brightness enhancement film as shown below, are mentioned. One kind of these optical layers may be used, two or more kinds may be used in combination, one layer may be used, or two or more layers may be laminated. The laminated polarizing plate further including such an optical layer is preferably used as an integrated polarizing plate having an optical compensation function, for example, and is suitable for use in various image display devices such as being disposed on the surface of a liquid crystal cell. ing.

Hereinafter, such an integrated polarizing plate will be described.
First, an example of a reflective polarizing plate or a transflective polarizing plate will be described. In the reflective polarizing plate, a reflective plate is further laminated on the laminated polarizing plate of the present invention, and in the transflective polarizing plate, a semi-transmissive reflective plate is further laminated on the laminated polarizing plate of the present invention.

  The reflective polarizing plate is usually disposed on the back side of the liquid crystal cell, and can be used for a liquid crystal display device (reflective liquid crystal display device) of a type that reflects incident light from the viewing side (display side). Such a reflective polarizing plate, for example, has an advantage that the liquid crystal display device can be thinned because the built-in light source such as a backlight can be omitted.

  The reflective polarizing plate can be produced by a conventionally known method such as a method of forming a reflecting plate made of metal or the like on one surface of a polarizing plate exhibiting an elastic modulus. Specifically, for example, one surface (exposed surface) of the transparent protective layer in the polarizing plate is matted as necessary, and a metal foil or vapor deposition film made of a reflective metal such as aluminum is formed on the surface as a reflection plate. The reflective polarizing plate etc. which were made are mentioned.

  In addition, as described above, a reflective polarizing plate or the like in which a reflective plate reflecting the fine concavo-convex structure is formed on the transparent protective layer containing fine particles in various transparent resins and having a fine concavo-convex structure on the surface. It is done. A reflector having a fine concavo-convex structure on its surface has an advantage that, for example, incident light can be diffused by irregular reflection to prevent directivity and glaring appearance and to suppress uneven brightness. For example, such a reflection plate is directly applied to a metal foil or a metal vapor deposition by a conventionally known method such as a vacuum vapor deposition method, an ion plating method, a sputtering method, or a plating method on the uneven surface of the transparent protective layer. It can be formed as a film.

  Moreover, instead of the method of directly forming the reflective plate on the transparent protective layer of the polarizing plate as described above, a reflective sheet having a reflective layer provided on an appropriate film such as a transparent protective film is used as the reflective plate. Also good. Since the reflection layer in the reflector is usually made of metal, for example, it is used from the viewpoint of preventing the decrease in the reflectance due to oxidation, and thus the long-term maintenance of the initial reflectance, and the separate formation of the transparent protective layer. The form is preferably such that the reflective surface of the reflective layer is covered with a film, a polarizing plate or the like.

  On the other hand, the transflective polarizing plate is a reflective polarizing plate having a transflective reflective plate instead of the reflective plate. Examples of the transflective reflector include a half mirror that reflects light through a reflective layer and transmits light.

  A transflective polarizing plate is usually provided on the back side of a liquid crystal cell. When a liquid crystal display device or the like is used in a relatively bright atmosphere, it reflects incident light from the viewing side (display side) and displays an image. In a relatively dark atmosphere, it can be used for a liquid crystal display device of a type that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate. In other words, the transflective polarizing plate can save the energy of using a light source such as a backlight in a bright atmosphere, while it can be used with a built-in light source in a relatively dark atmosphere. Useful for formation.

Next, an example of a polarizing plate in which a brightness enhancement film is further laminated on the laminated polarizing plate of the present invention will be described.
The brightness enhancement film is not particularly limited. For example, it transmits linearly polarized light having a predetermined polarization axis, such as a dielectric multilayer thin film or a multilayer laminate of thin film films having different refractive index anisotropy, and the like. For example, the light having the characteristic of reflecting can be used. As such a brightness enhancement film, for example, a trade name “D-BEF” manufactured by 3M Corporation may be mentioned. Also, a cholesteric liquid crystal layer, in particular an oriented film of a cholesteric liquid crystal polymer, or a film in which the oriented liquid crystal layer is supported on a film substrate can be used.
These reflect the right and left circularly polarized light and transmit the other light. For example, the product name “PCF350” manufactured by Nitto Denko Corporation, the product name “Transmax” manufactured by Merck, etc. Can be mentioned.

The various polarizing plates of the present invention as described above may be, for example, optical members obtained by stacking the laminated polarizing plate of the present invention and two or more optical layers.
An optical member in which two or more optical layers are laminated in this manner can be formed by a method of sequentially laminating separately, for example, in the manufacturing process of a liquid crystal display device or the like. There are advantages such as excellent quality stability and assembly workability, and improvement in manufacturing efficiency of liquid crystal display devices and the like. For the lamination, various adhesive means such as an adhesive layer can be used as described above.

  The various polarizing plates as described above preferably have a pressure-sensitive adhesive layer or an adhesive layer since they can be easily laminated on other members such as a liquid crystal cell. Can be placed on one or both sides. The material of the adhesive layer is not particularly limited, and a conventionally known material such as an acrylic polymer can be used. Particularly, prevention of foaming and peeling due to moisture absorption, deterioration of optical characteristics due to a difference in thermal expansion, and prevention of warpage of the liquid crystal cell. From the viewpoint of the formability of a liquid crystal display device having high quality and excellent durability, it is preferable that the pressure-sensitive adhesive layer has a low moisture absorption rate and excellent heat resistance. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient. The pressure-sensitive adhesive layer is formed on the surface of the polarizing plate by, for example, forming a layer by directly adding a solution or melt of various pressure-sensitive adhesive materials to a predetermined surface of the polarizing plate by a developing method such as casting or coating. It can be performed by a method, a method in which a pressure-sensitive adhesive layer is formed on a separator, which will be described later, and transferred to a predetermined surface of a polarizing plate. Such a layer may be formed on any surface of the polarizing plate, for example, on the exposed surface of the retardation plate in the polarizing plate.

  Thus, when the surface of the pressure-sensitive adhesive layer or the like provided on the polarizing plate is exposed, it is preferable to cover the surface with a separator for the purpose of preventing contamination until the pressure-sensitive adhesive layer is put to practical use. This separator can be formed on a suitable film such as a transparent protective film by a method of providing one or more release coats with a release agent such as silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, etc., if necessary. .

For example, the pressure-sensitive adhesive layer may be a single layer or a laminate. As the laminate, for example, a laminate in which different compositions and different types of single layers are combined can be used. Moreover, when arrange | positioning on both surfaces of a polarizing plate, the same adhesive layer may respectively be sufficient, for example, a different composition and a different kind of adhesive layer may be sufficient.
The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to, for example, the configuration of the polarizing plate, and is generally 1 to 500 μm.
As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer, for example, those having excellent optical transparency and exhibiting appropriate wettability, cohesiveness and adhesive pressure-sensitive adhesive properties are preferable. Specific examples include pressure-sensitive adhesives that are appropriately prepared using a polymer such as an acrylic polymer, silicone polymer, polyester, polyurethane, polyether, and synthetic rubber as a base polymer.
Control of the adhesive properties of the pressure-sensitive adhesive layer can be achieved by, for example, controlling the degree of crosslinking and molecular weight depending on the composition and molecular weight of the base polymer forming the pressure-sensitive adhesive layer, the crosslinking method, the content ratio of the crosslinkable functional group, the blending ratio of the crosslinking agent, etc. It can be suitably performed by a conventionally known method such as adjustment.

  The optical film and polarizing plate of the present invention as described above, and various layers such as a polarizing film, a transparent protective layer, an optical layer, and a pressure-sensitive adhesive layer forming various optical members (various polarizing plates laminated with optical layers) are, for example, salicylic acid. It may have an ultraviolet absorbing ability by appropriately treating with an ultraviolet absorber such as an ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex salt compound.

  As described above, the optical film or polarizing plate of the present invention is preferably used for forming various devices such as a liquid crystal display device. For example, the optical film or polarizing plate of the present invention is disposed on one side or both sides of a liquid crystal cell. Thus, a liquid crystal panel can be used for a liquid crystal display device such as a reflective type, a transflective type, or a transmissive / reflective type.

  The type of liquid crystal cell forming the liquid crystal display device can be arbitrarily selected, for example, an active matrix drive type represented by a thin film transistor type, a simple matrix drive type represented by a twist nematic type or a super twist nematic type Various types of liquid crystal cells can be used. Among these, the optical film and the polarizing plate of the present invention are very useful for optical compensation of VA (Vertical Aligned) cells, and are very useful as viewing angle compensation films for VA mode liquid crystal display devices. It is.

  The liquid crystal cell is usually a structure in which liquid crystal is injected into the gap between the opposing liquid crystal cell substrates. The liquid crystal cell substrate is not particularly limited, and for example, a glass substrate or a plastic substrate can be used. The material for the plastic substrate is not particularly limited, and conventionally known materials can be used.

  Moreover, when providing a polarizing plate and an optical member on both surfaces of a liquid crystal cell, they may be the same kind and may differ. Furthermore, when forming the liquid crystal display device, for example, appropriate components such as a prism array sheet, a lens array sheet, a light diffusing plate, and a backlight can be arranged in one or more layers at appropriate positions.

  Furthermore, the liquid crystal display device of the present invention includes a liquid crystal panel, and is not particularly limited except that the liquid crystal panel of the present invention is used as the liquid crystal panel. In the case of including a light source, the light source is not particularly limited. However, for example, a plane light source that emits polarized light is preferable because the energy of light can be used effectively.

  An example of the liquid crystal panel of the present invention is shown in the sectional view of FIG. As illustrated, the liquid crystal panel 40 includes a liquid crystal cell 21, an optical film 1, a polarizer 2, and a transparent protective layer 3, and the optical film 1 is laminated on one surface of the liquid crystal cell 21. The polarizer 2 and the transparent protective layer are laminated in this order on the other surface. The liquid crystal cell has a configuration in which liquid crystal is held between two liquid crystal cell substrates (not shown). The optical film 1 is a laminate of the birefringent layer (a) and the transparent film (b) as described above, the birefringent layer side facing the liquid crystal cell, and the transparent film side facing the polarizer 2. ing.

  In the liquid crystal display device of the present invention, for example, a diffusion plate, an antiglare layer, an antireflection film, a protective layer and a protective plate are further arranged on the viewing-side optical film (polarizing plate), or a liquid crystal cell in a liquid crystal panel. A compensation retardation plate or the like may be appropriately disposed between the polarizing plate and the polarizing plate.

  In addition, the optical film and polarizing plate of this invention are not limited to the above liquid crystal display devices, For example, it can be used also for self-luminous display devices, such as an organic electroluminescence (EL) display, PDP, and FED. When used in a self-luminous flat display, for example, circular polarization can be obtained by setting the in-plane retardation value Δnd of the birefringent optical film of the present invention to λ / 4. Available.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
[Example 1]
(Preparation of cellulose acetate solution)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution A.

(Cellulose acetate solution A composition)
Cellulose acetate having an acetylation degree of 2.86 100.0 parts by mass Methylene chloride (first solvent) 402.0 parts by mass Methanol (second solvent) 60.0 parts by mass

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

(Matting agent solution composition)
Silica particle dispersion 10.0 parts by mass Methylene chloride having an average particle diameter of 16 nm (first solvent) 76.3 parts by mass Methanol (second solvent) 3.4 parts by mass Cellulose acetate solvent solution A 10.3 parts by weight

(Preparation of additive solution)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution. The compounds shown in Table 4 below were used for the compounds and wavelength dispersion adjusting agents that reduce the optical anisotropy.

(Additive solution composition)
Compound that lowers optical anisotropy 49.3 parts by weight Wavelength dispersion adjusting agent 7.6 parts by weight Methylene chloride (first solvent) 58.4 parts by weight Methanol (second solvent) 8.7 parts by weight Cellulose acetate solution A 12.8 parts by mass

(Preparation of cellulose acetate film sample 1)
94.6 parts by mass of the cellulose acetate solution A, 1.3 parts by mass of the matting agent solution, and 4.1 parts by mass of the additive solution were mixed after filtration, and cast using a band casting machine. The mass ratio of the compound that reduces optical anisotropy and the wavelength dispersion adjusting agent to cellulose acetate in the above composition was 12% and 1.8%, respectively. The film was peeled from the band with a residual solvent amount of 30% and dried at 140 ° C. for 40 minutes to produce a cellulose acetate film. The resulting cellulose acetate film had a residual solvent amount of 0.2% and a film thickness of 80 μm.

(Production of cellulose acetate film samples 2, 3, 15 to 18)
Cellulose acetate film samples 2, 3, 15 to 18 were produced in the same manner except that the types and amounts of the compound that reduces the optical anisotropy in the additive solution and the wavelength dispersion adjusting agent were changed to those shown in Table 1. . Table 1 also shows the solution composition of Sample 1 preparation. When the difference ΔRth (= Rth10% RH−Rth80% RH) in the film thickness direction between the relative humidity 10% and the relative humidity 80% of these samples was measured, the optical anisotropy reducing agent of the present invention was added. In Comparative Samples 15 and 16 that were not added and in Comparative Samples 17 and 18 to which the plasticizer biphenyldiphenyl phosphate (BDP) was added instead of the optical anisotropy reducing agent, ΔRth did not become 30 nm or less and the optical anisotropy Humidity dependence was great.
On the other hand, Oite the sample 2 containing the optical anisotropy lowering agent of the present invention ΔRth is in the range of 0 to 30 nm, it was confirmed that humidity dependence is reduced. Further, the distribution of Re and Rth in the width direction was small, and there was little optical unevenness. Further, when the equilibrium water content at 25 ° C. and 80% RH of these samples was measured, all of them were 4% or less except for the comparative sample 15, and cellulose was added by adding the optical anisotropy reducing agent or wavelength dispersion adjusting agent of the present invention. It was confirmed that the acylate film was hydrophobized. Furthermore, when 60 ° C., 95% RH, and 24 hr moisture permeability (in terms of 80 μm) of these samples were measured, all samples except for the comparative sample 15 were 400 g / m ² · 24 hr to 2000 g / m ² · 24 hr, Further, it was confirmed that the moisture permeability of samples 1 to 3 to which the optical anisotropy reducing agent and the wavelength dispersion adjusting agent of the present invention were added as compared with comparative samples 16 and 17 was improved. In addition, the samples other than the comparative sample 18 had no cloudiness of the film, and a sufficiently transparent film could be prepared. However, in the comparative sample 18, the total amount of the additive compound was as high as 49% with respect to the cellulose acylate, In this case, the film was clouded and the compound was precipitated (crying out), and could not be evaluated as a transparent cellulose acylate film .

Samples 1 to 3 using the compound that reduces the optical anisotropy of the present invention are comparative samples 15 and 16 that do not use these compounds and a general plasticizer, and Log P is 7.3, which is outside the scope of the present invention. As compared with the comparative sample 17 using biphenyl-diphenyl phosphate (BDP), both Re (630) and Rth (630) are sufficiently decreased, and optically nearly isotropic. ing. In addition, in the sample using the compound for adjusting wavelength dispersion of the present invention in combination, all of the samples | Re ( ₄₀₀ ) -Re ( ₇₀₀ ) | and | Rth ( ₄₀₀ ) -Rth ( ₇₀₀ ) | The chromatic dispersion is approaching zero.

(Example 2)
Synthesis from 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB) The polyimide having a mass average molecular weight (Mw) of 70,000 represented by the following formula (6) was dissolved in cyclohexanone to prepare a 15% by mass polyimide solution. In addition, the preparation of a polyimide, etc. referred the method of literature (F. Li et al. Polymer40 (1999) 4571-4583). On the other hand, the triacetylcellulose (TAC) film 1 having a thickness of 80 μm of Example 1 was stretched 1.3 times at 175 ° C. by fixed-end lateral stretching to produce a stretched TAC film having a thickness of 75 μm. And the polyimide solution was apply | coated on this extending | stretched TAC film, and this was dried for 10 minutes at 100 degreeC. As a result, a completely transparent and smooth polyimide film having a thickness of 6 μm and Δn (a) of about 0.04 on a stretched TAC film (transparent film (b)) of 75 μm and Δn (b) of about 0.0006 ( An optical film on which the birefringent layer (a)) was laminated was obtained. This optical film was excellent in humidity dependency and wavelength dispersion, and had small in-plane variation in optical performance. Moreover, it was an optical film having a birefringent layer having optical characteristics of nx>ny> nz.
The same was true when the films 2 and 3 of Example 1 were used instead of the film 1.

Example 3
Polyetherketone (Mw: 500,000) represented by the following formula (18) was dissolved in methyl isobutyl ketone to prepare a 20% by mass varnish. This varnish was applied on the same stretched TAC film 1 as in Example 2, and dried at 100 ° C. for 10 minutes. As a result, a completely transparent and smooth polyether ketone having a thickness of 75 μm and a Δn (b) of about 0.0006 on a stretched TAC film (transparent film (b)) having a thickness of 10 μm and a Δn (a) of about 0.02. An optical film on which a film (birefringent layer (a)) was laminated was obtained. This optical film was excellent in humidity dependency and wavelength dispersion, and had small in-plane variation in optical performance. Moreover, it was an optical film having a birefringent layer having optical characteristics of nx>ny> nz. The same was true when the films 2 and 3 of Example 1 were used instead of the film 1.

Formula (18)

(Example 4)
Polyimide synthesized from 4,4′-bis (3,4-dicarboxyphenyl) -2,2-diphenylpropane dianhydride and 2,2′-dichloro-4,4′-diaminobiphenyl (Mw: 30,000) was dissolved in cyclopentanone to prepare a 20 mass% polyimide solution. This solution was applied on the unstretched TAC film 1 having a thickness of 80 μm of Example 1, dried at 130 ° C. for 5 minutes, and then stretched by 10% by longitudinal uniaxial stretching at 150 ° C. As a result, on a completely transparent and smooth TAC film (transparent film (b)) having a thickness of 80 μm and Δn (b) of about 0.0006, a polyimide film (compound of about 5 μm and Δn (a) of about 0.025 was used. An optical film on which the refractive layer (a)) was laminated was obtained. This optical film was excellent in humidity dependency and wavelength dispersion, and had small in-plane variation in optical performance. Moreover, it was an optical film having a birefringent layer having optical characteristics of nx>ny> nz. The same was true when the films 2 and 3 of Example 1 were used instead of the film 1.

(Example 5)
Polyimide synthesized from 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (Mw: 100,000) was dissolved in cyclohexanone to prepare a 15% by weight polyimide solution. This solution was applied on the unstretched TAC film 1 having a thickness of 80 μm of Example 1, dried at 130 ° C. for 5 minutes, and then stretched by 10% by longitudinal uniaxial stretching at 150 ° C. As a result, on a completely transparent and smooth TAC film (transparent film (b)) having a thickness of 80 μm and Δn (b) of about 0.0006, a polyimide film (duplex of about 6 μm and Δn (a) of about 0.04 was obtained. An optical film on which the refractive layer (a)) was laminated was obtained. This optical film was excellent in humidity dependency and wavelength dispersion, and had small in-plane variation in optical performance. Moreover, it was an optical film having a birefringent layer having optical characteristics of nx>ny> nz. The same was true when the films 2 and 3 of Example 1 were used instead of the film 1.

(Example 6)
The polyimide similar to Example 1 was melt | dissolved in methyl isobutyl ketone, and the 25 mass% polyimide solution was prepared. This solution was coated on the stretched TAC film 1 of Example 1 similar to Example 1, and dried at 160 ° C. for 5 minutes. As a result, a completely transparent and smooth polyimide film having a thickness of 6 μm and Δn (a) of about 0.04 on a stretched TAC film (transparent film (b)) of 75 μm and Δn (b) of about 0.0006 ( An optical film on which the birefringent layer (a)) was laminated was obtained. This optical film was excellent in humidity dependency and wavelength dispersion, and had small in-plane variation in optical performance. Moreover, it was an optical film having a birefringent layer having optical characteristics of nx>ny> nz. The same was true when the films 2 and 3 of Example 1 were used instead of the film 1.

(Example 7)
The same polyimide solution as in Example 1 was coated on the unstretched TAC film 1 having a thickness of 80 μm in Example 1, and dried at 100 ° C. for 10 minutes. As a result, on a completely transparent and smooth TAC film (transparent film (b)) having a thickness of 80 μm and Δn (b) of about 0.0006, a polyimide film (compound of 4 μm and Δn (a) of about 0.025) An optical film on which the refractive layer (a)) was laminated was obtained. This film was excellent in humidity dependency and wavelength dispersion, and had small in-plane variation in optical performance. Moreover, it was an optical film having a birefringent layer having optical characteristics of nx≈ny> nz. The same applies to the case of using the films 2 and 3 of Example 1 instead of the film 1.

(Comparative Example 1)
An optical film was produced in the same manner as in Example 2 except that the TAC film was changed to the comparative sample films 15 to 18 produced in Example 1.
(Comparative Example 2)
An optical film was produced in the same manner as in Example 3 except that the TAC film was changed to the comparative sample films 15 to 18 produced in Example 1.
(Comparative Example 3)
An optical film was produced in the same manner as in Example 4 except that the TAC film was changed to the comparative sample films 15 to 18 produced in Example 1.
(Comparative Example 4)
An optical film was produced in the same manner as in Example 5 except that the TAC film was changed to the comparative sample films 15 to 18 produced in Example 1.
(Comparative Example 5)
An optical film was produced in the same manner as in Example 6 except that the TAC film was changed to the comparative sample films 15 to 18 produced in Example 1.
(Comparative Example 6)
An optical film was produced in the same manner as in Example 7 except that the TAC film was changed to the comparative sample films 15 to 18 produced in Example 1.

  Table 2 shows the performance of the produced optical film. (As a representative example, the values for the case of using film 1 and film 15 are shown.)

  Table 3 shows the evaluation results for the produced birefringent layer (a).

(Evaluation of display characteristics)
And the optical film obtained in Examples 1-7 and Comparative Examples 1-6 is laminated | stacked through a commercially available polarizing plate (The product name "HEG1425DU" by Nitto Denko Corporation) and an acrylic adhesive. An optical compensation layer-integrated laminated polarizing plate was produced. In addition, it laminated | stacked so that a polarizing plate and the transparent film (b) base material of an optical film might face. Further, this laminated polarizing plate was bonded to the backlight side of the liquid crystal cell so that the polarizing plate was on the outside, thereby producing a liquid crystal display device.
Then, the display characteristics of these liquid crystal display devices were evaluated. As a result, it was shown that when the optical film of each example was used, even when viewed from an oblique direction, the difference in color was small compared to when viewed from the front, and there was little unevenness in the screen.
(Change in color seen from an angle)
Almost the same color as the front: ○
The color is so different that it is visible: △
Difficult to appreciate due to different colors: ×
(Unevenness in the screen)
There is 1 point or less of thin unevenness of 3 cm square or less: ○
Thin unevenness of 3 cm square or less is 1 point or more and 3 points or less: Δ
There are 3 or more 3cm square irregularities: ×
From the results, it was confirmed that the liquid crystal display device using the film of the example excellent in wavelength dispersion did not change in color even when viewed obliquely. In addition, it was confirmed that the liquid crystal display device using the film of the example with small optical unevenness of Re and Rth has little unevenness in the screen. Furthermore, in the example, in the wide viewing angle range of the front and the perspective, not only the contrast and display uniformity are excellent, but also the occurrence of rainbow unevenness is suppressed. Among the examples, in particular, in the case of the optical films of Examples 1 to 6 where the condition (II) is 100 or less, generation of rainbow unevenness was sufficiently avoided, and extremely excellent display quality was exhibited.

The manufactured liquid crystal display device was left in an atmosphere of 25 ° C., 10% RH and 25 ° C., 80% RH for 24 hours, and then the display performance was checked to see if there was a difference in display performance depending on the humidity.
(Humidity dependency of display performance)
No difference in display performance due to humidity: ○
There is a difference in display performance, but I do not care: △
There is a big difference in display performance, and I am very worried about: ×
The liquid crystal display device using the film of the example having a small difference in performance of Re and Rth due to humidity has a small difference in display performance in an atmosphere of 25 ° C. and 10% RH and an atmosphere of 25 ° C. and 80% RH. It was confirmed that the film of the comparative example was superior to the case of using the film.

The prepared liquid crystal display device was left in an atmosphere of 60 ° C. and 90% RH for 120 hours and then left in a 25 ° C. and 60% RH atmosphere for 24 hours, and then the display performance was confirmed. It was confirmed that it did not deteriorate.
(Change in display performance due to wet heat thermo)
No display unevenness (light leakage, color unevenness, etc.) even with wet heat thermography: ○
Part of the screen has light leakage and color unevenness of 3cm square or less: △
There is light leakage and color unevenness of 3cm square or more on the entire screen: ×
It can be confirmed that the liquid crystal display device using the film of the example with a small difference in performance of Re and Rth due to humidity has no display unevenness even when wet heat thermostat and is superior to the case of using the film of the comparative example. It was.

These results are shown in Table 4. As representative examples, Examples 2 to 7 show the results when the film 1 is used, and Comparative Examples 1 to 6 show the results when the film 15 is used. Even when the films 2 and 3 were used, a liquid crystal display device excellent in display performance could be produced as in the case where the film 1 was used. In addition, when the films 16 to 18 were used, the display performance was inferior to that of the example as in the case of the film 15, but the case of using the film 15 inferior in wavelength dispersion and humidity dependency was oblique. The color change from, the humidity dependence of the display performance, and the display performance after the wet heat thermostat were inferior to the examples.

  As described above, if an optical film and a polarizing plate produced using the film of the present invention are used, there is little change in color from an oblique direction, there is little unevenness on the screen, and the display performance is also dependent on humidity. It is possible to realize a thin liquid crystal display device which is excellent and has excellent display quality in which generation of rainbow unevenness is suppressed.

It is a perspective view which shows the optical axis direction in this invention. It is sectional drawing of an example of the laminated polarizing plate of this invention. It is sectional drawing of other examples of the laminated polarizing plate of this invention. It is sectional drawing which shows an example of the liquid crystal panel of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical film 2 Polarizer 3 Protective layer 10 Birefringence layer (a)
20, 30 laminated polarizing plate 21 liquid crystal cell 40 liquid crystal panel

Claims (20)

An optical film birefringent layer (a) is laminated on the transparency film is a cellulose acylate film containing the compound decreasing optical anisotropy (b), the birefringent layer (a) is below Re retardation value and Rth retardation value satisfying the conditions of the formulas (I) and (II) and measured in an environment of 25 ° C. and 10% RH, and Re retardation value and Rth measured in an environment of 25 ° C. and 80% RH the difference of the retardation value, within 20nm each state, and are within 50nm,
The optical film, wherein the compound for reducing optical anisotropy has an octanol-water partition coefficient of 0 to 7, a molecular weight of 150 or more and 3000 or less, and represented by the following general formula (13): .
Formula (13)

[Wherein, R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group, or an aryl group. ]
Formula (I): 1 <(nx-nz) / (nx-ny)
Formula (II): 0.0005 ≦ Δn (a) ≦ 0.5
(In the formula (II), Δn (a) is the birefringence of the birefringent layer (a) represented by the following formula, and in the formula (I) and the following formula, nx, ny and nz are respectively double The refractive indexes of the refractive layer (a) in the X-axis, Y-axis, and Z-axis directions are shown, where the X-axis is the axial direction indicating the maximum refractive index in the plane of the birefringent layer (a), and the Y-axis. Is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis.
Δn (a) = [(nx + ny) / 2] −nz) The optical film according to claim 1, wherein Re ₍ λ ₎ and Rth ₍ λ ₎ satisfy the following formula (I ′).
Formula (I ′): | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35
(In the formula, Re ₍ λ ₎ is the front retardation value (unit: nm) at the wavelength λnm, and Rth (λ ₎ is the retardation value (unit: nm) in the film thickness direction at the wavelength λnm.) 3. The optical film according to claim 1, wherein the in-plane variation of Re and Rth satisfies the following mathematical formulas (III) and (IV): 3.
(III): | Re _(MAX) −Re _(MIN) | ≦ 3
(IV): | Rth _(MAX) −Rth _(MIN) | ≦ 5
(In the formula, Re _(MAX) and Rth _(MAX) are the maximum retardation values of 1 m square film cut out arbitrarily, and Re _(MIN) and Rth _(MIN) are the minimum values.) The Re ₍ λ ₎ and Rth ₍ λ ₎ of the transparent film (b), which is the cellulose acylate film constituting the laminate, satisfy the following formulas (V) and (VI). The optical film in any one of thru | or 3.
Formula (V): 0 ≦ Re ₍₆₃₀₎ ≦ 10 and | Rth ₍₆₃₀₎ | ≦ 25
Formula (VI): | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35
(In the formula, Re ₍ λ ₎ is the front retardation value (unit: nm) at the wavelength λnm, and Rth ₍ λ ₎ is the retardation value (unit: nm) in the film thickness direction at the wavelength λnm.) 5. The optical film according to claim 4, wherein the cellulose acylate film contains at least one compound that reduces the retardation Rth in the film thickness direction within a range satisfying the following formulas (VII) and (VIII). .
Formula (VII): (Rth (A) −Rth (0)) / A ≦ −1.0
Formula (VIII): 0.01 ≦ A ≦ 30
(Here, Rth (A) represents Rth (nm) of a film containing A% of a compound that lowers Rth, and Rth (0) represents Rth (nm) of a film not containing a compound that lowers Rth. In addition, A is the mass (%) of the compound when the mass of the film raw material polymer is 100.) The cellulose acylate film is a cellulose acylate having an acyl substitution degree of 2.85 to 3.00, at least one compound for reducing Re ₍ λ ₎ and Rth ₍ λ _), and 0 for the cellulose acylate solid content. The optical film according to claim 4, comprising 0.01 to 30% by mass. The cellulose acylate film has at least one compound that lowers | Re ₍₄₀₀₎ -Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ -Rth ₍₇₀₀₎ | The optical film according to claim 4, comprising from 01 to 30% by mass.   The optical film according to claim 4, wherein the cellulose acylate film has a film thickness of 10 to 120 μm.   The optical film according to any one of claims 1 to 8, wherein the birefringent layer (a) is directly laminated on the transparent film (b).   10. The optical film according to claim 1, wherein the material forming the birefringent layer (a) is a non-liquid crystalline material. Non-liquid crystal material, an optical film according to claim 1 0, characterized polyamide, polyimide, polyester, polyetherketone, is at least one polymer material selected from the group consisting of polyamideimide and polyesterimide. The optical film according to any one of claims 9 to 11, wherein at least one of an adhesive layer and a pressure-sensitive adhesive layer is laminated on the outermost layer. 請 Motomeko at least one optical film according to any one of 1 to 1 2, polarizing plates, characterized in that it comprises as a protective film for the polarizer. Includes a liquid crystal cell and the optical member, a liquid crystal panel in which the optical member is disposed on at least one surface of the liquid crystal cell, the optical member is an optical film according to any one of claims 1 to 1 2 or Claim 1 4. A liquid crystal panel, which is the polarizing plate according to 3 . A liquid crystal display comprising a liquid crystal panel, a liquid crystal display device, wherein the liquid crystal panel is a liquid crystal panel according to claim 1 4, wherein. The liquid crystal display device characterized by having either a polarizing plate according to the optical film and the first to third aspects according to claim 1 to 1 2. VA liquid crystal display device characterized by having either a polarizing plate according to the optical film and the claims 1 3 according to any one of claims 1 to 1 2. The VA liquid crystal display device according to claim 17 , which has polarizing plates on both upper and lower sides of the liquid crystal cell, wherein the optical film according to any one of claims 1 to 12 is provided on at least one cell side of the polarizing plate. A liquid crystal display device. An optical film in which a birefringent layer (a) is laminated on a transparent film (b) which is a cellulose acylate film containing a compound for reducing optical anisotropy, and the birefringent layer (a) is represented by the following formula: Satisfying the conditions of (I) and (II) and formed from a non-liquid crystalline material;
  The optical film, wherein the compound for reducing optical anisotropy has an octanol-water partition coefficient of 0 to 7, a molecular weight of 150 or more and 3000 or less, and represented by the following general formula (13): .
Formula (13)

[Wherein R ¹ Represents an alkyl group or an aryl group, and R ² And R ^Three Each independently represents a hydrogen atom, an alkyl group or an aryl group. ]
Formula (I): 1 <(nx−nz) / (nx−ny)
  Formula (II): 0.0005 ≦ Δn (a) ≦ 0.5
(In the formula (II), Δn (a) is the birefringence of the birefringent layer (a) represented by the following formula, and in the formula (I) and the following formula, nx, ny and nz are respectively double The refractive indexes of the refractive layer (a) in the X-axis, Y-axis, and Z-axis directions are shown, where the X-axis is the axial direction indicating the maximum refractive index in the plane of the birefringent layer (a), and the Y-axis. Is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis.
  Δn (a) = [(nx + ny) / 2] −nz)   The optical film according to claim 19, wherein the non-liquid crystalline material is at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide.

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