JP5772529B2 - Optical film, polarizing plate, and liquid crystal display device - Google Patents

Description

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

  Resin films such as cellulose ester, polycarbonate, and polyolefin are used as optical films for liquid crystal display devices. Especially, since the resin film (cellulose ester film) containing a cellulose ester is easy to bond with the polyvinyl alcohol film which is a polarizer, it is widely used.

  In recent years, development of thin and light notebook computers and thin and large-screen TVs has been progressing. Accordingly, the optical film constituting the liquid crystal display device is also required to be thin, large and high performance. In particular, since an optical film constituting a VA liquid crystal display device is required to have a certain retardation or more, a retardation increasing agent or the like is generally included.

  For example, Patent Document 1 discloses a cellulose ester film containing a discotic compound as a retardation increasing agent. However, in order to obtain a desired retardation value, it is necessary to contain a certain amount or more of the retardation increasing agent. Therefore, the obtained cellulose ester film has a problem that it tends to exhibit forward wavelength dispersibility, thereby causing a so-called color shift (color unevenness) in which the color tone in an oblique direction changes.

  That is, “wavelength dispersion” refers to the degree of variation in the phase difference (phase difference between the fast axis and the slow axis due to birefringence) in light of each wavelength. “Forward wavelength dispersion” means that the in-plane retardation value (Ro1) for light of a specific wavelength and the in-plane retardation value (Ro2) for light of a longer wavelength than a specific wavelength are both positive. And the property that the value of Ro1 / Ro2 exceeds 1.0. “Reverse wavelength dispersion” means that the in-plane retardation (Ro1) for light of a specific wavelength and the in-plane retardation (Ro2) for light of a longer wavelength than a specific wavelength are both positive. And Ro1 / Ro2 has a value of less than 1.0. “Flat wavelength dispersion” refers to the property that the value of Ro1 / Ro2 is 1.0. In order to enhance the display performance of a VA liquid crystal display device, the optical film included in the liquid crystal display device is usually required to have reverse wavelength dispersion or flat wavelength dispersion.

  For example, as a retardation control agent imparting reverse wavelength dispersion, a cellulose ester film (Patent Document 2) made of a cellulose composition containing a specific low-molecular compound, or an optical film containing a specific compound having a polymerizable group ( Patent Document 3) has been proposed.

JP 2001-166144 A JP 2010-163483 A JP 2010-31223 A

  However, the specific low molecular weight compound described in Patent Document 2 can control the refractive index in the direction orthogonal to the orientation axis of the cellulose ester, but imparts sufficient reverse wavelength dispersion to the optical film. Was difficult. In addition, the compound having a polymerizable group described in Patent Document 3 can be oriented by stretching; the orientation state can be fixed and the refractive index can be controlled by a polymerization reaction. Therefore, compared with the method of controlling the orientation state only by stretching the film, it is necessary to cause a compound having a polymerizable group to undergo a polymerization reaction after stretching, so that there is a problem that the film production process becomes complicated.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical film that exhibits reverse wavelength dispersion or flat wavelength dispersion and has excellent durability. It is another object of the present invention to provide a liquid crystal display device including the optical film, having a wide viewing angle and excellent durability.

（式（１）中、
Ｃｙｃは、２価の５員環または６員環を含む環状基を表し、前記５員環または６員環は、他の環と縮合していてもよく；
Ｒ_３は、前記環状基が有する置換基を表し；
ｊは、０〜４の整数を表し、ｊが０であるとき、前記５員環または６員環は、他の環と縮合しており；
Ｌ_１およびＬ_２は、それぞれ独立に単結合、−Ｏ−、−ＣＯ−、−ＮＲａ−（Ｒａは、炭素原子数１〜７のアルキル基または水素原子）、−Ｓ−、−ＳＯ_２−および−ＣＨ_２−からなる群より選ばれる２価の連結基を表し；
Ｓｔｒ_１およびＳｔｒ_２は、それぞれ独立にステロイド類の残基を表し；
Ｒ_１およびＲ_２は、それぞれ独立に置換基を表し；
ｍおよびｎは、それぞれ独立に０〜１０の整数を表す）
［２］ 前記一般式（１）で表される化合物において、前記（Ｒ_３）ｊを有するＣｙｃが、下記一般式（２）または一般式（３）で表される構造を含む、［１］に記載の光学フィルム。

（式（２）中、
Ｘ_１およびＸ_２は、それぞれ独立に−Ｓ−、−Ｏ−または−ＮＲｂ−（Ｒｂは、炭素原子数が１〜７のアルキル基または水素原子）を表し；
Ｒ_４およびＲ_５は、それぞれ独立に水素原子または置換基を表し；
−＊は、前記Ｌ_１またはＬ_２との連結部を表す）

（式（３）中、
Ｘ_３は、−Ｓ−、−Ｏ−または−ＮＲｂ−（Ｒｂは、炭素原子数が１〜７のアルキル基または水素原子）を表し；
Ｒ_６は、水素原子または置換基を表し；
−＊は、前記Ｌ_１またはＬ_２との連結部を表す）
［３］ 前記一般式（１）で表される化合物において、前記ステロイド類の残基に含まれるステロイド核の３位または１７位の炭素原子と、前記Ｌ_１またはＬ_２とが直接または連結基を介して結合している、［１］または［２］に記載の光学フィルム。
［４］ 前記一般式（１）で表される化合物において、前記（Ｒ_１）ｍを有するＳｔｒ_１または前記（Ｒ_２）ｎを有するＳｔｒ_２は、コレステロール誘導体またはコール酸誘導体から誘導される、［１］〜［３］のいずれかに記載の光学フィルム。
［５］ セルロースエステルをさらに含有する、［１］〜［４］のいずれかに記載の光学フィルム。
［６］ 前記セルロースエステルのアシル基の総置換度が２．４以上３．０以下である、［５］に記載の光学フィルム。
［７］ ２３℃、５５％ＲＨの環境下で、波長５９０ｎｍの光における、下記式（Ｉ）で表されるリターデーションＲｏが４０〜１００ｎｍ、下記式（II）で表されるＲｔｈが１００〜３００ｎｍである、［１］〜［６］のいずれかに記載の光学フィルム。
式（Ｉ） Ｒｏ＝（ｎｘ−ｎｙ）×ｄ
式（II） Ｒｔｈ＝｛（ｎｘ＋ｎｙ）／２−ｎｚ｝×ｄ
（ｎｘは、光学フィルムの面内方向において屈折率が最大になる方向ｘにおける屈折率を表し；
ｎｙは、光学フィルムの面内方向において、前記方向ｘと直交する方向ｙにおける屈折率を表し；
ｎｚは、光学フィルムの厚み方向ｚにおける屈折率を表し；
ｄ（ｎｍ）は光学フィルムの厚みを表す）
［８］ 前記光学フィルムの膜厚が２０〜３５μｍである、［１］〜［７］のいずれかに記載の光学フィルム。 [1] An optical film containing a compound represented by the following general formula (1).

(In the formula (1),
Cyc represents a cyclic group containing a divalent 5-membered ring or 6-membered ring, and the 5-membered ring or 6-membered ring may be condensed with another ring;
R ₃ represents a substituent of the cyclic group;
j represents an integer of 0 to 4, and when j is 0, the 5-membered or 6-membered ring is condensed with another ring;
L ₁ and L ₂ are each independently a single bond, —O—, —CO—, —NRa— (Ra is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom), —S—, —SO ₂ —. And a divalent linking group selected from the group consisting of —CH ₂ —;
Str ₁ and Str ₂ each independently represents a steroid residue;
R ₁ and R ₂ each independently represent a substituent;
m and n each independently represents an integer of 0 to 10)
[2] In the compound represented by the general formula (1), the Cyc having the (R ₃ ) j includes a structure represented by the following general formula (2) or the general formula (3) [1] The optical film described in 1.

(In the formula (2),
X ₁ and X ₂ each independently represent —S—, —O— or —NRb— (Rb represents an alkyl group having 1 to 7 carbon atoms or a hydrogen atom);
R ₄ and R ₅ each independently represents a hydrogen atom or a substituent;
- * represents a linking portion between the _{L 1} or _{L 2)}

(In formula (3),
X ₃ represents -S-, -O-, or -NRb- (Rb is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom);
R ₆ represents a hydrogen atom or a substituent;
- * represents a linking portion between the _{L 1} or _{L 2)}
[3] In the compound represented by the general formula (1), the carbon atom at the 3-position or 17-position of the steroid nucleus contained in the residue of the steroid and the L ₁ or L ₂ are directly or a linking group. The optical film according to [1] or [2], which is bonded via
[4] In the compound represented by the general formula (1), Str ₁ having (R ₁ ) m or Str ₂ having (R ₂ ) n is derived from a cholesterol derivative or a cholic acid derivative. The optical film according to any one of [1] to [3].
[5] The optical film according to any one of [1] to [4], further containing a cellulose ester.
[6] The optical film according to [5], wherein the total substitution degree of acyl groups of the cellulose ester is 2.4 or more and 3.0 or less.
[7] Under an environment of 23 ° C. and 55% RH, the retardation Ro represented by the following formula (I) is 40 to 100 nm and the Rth represented by the following formula (II) is 100 to 100 at a wavelength of 590 nm. The optical film according to any one of [1] to [6], which is 300 nm.
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the optical film;
ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the optical film;
nz represents the refractive index in the thickness direction z of the optical film;
d (nm) represents the thickness of the optical film)
[8] The optical film according to any one of [1] to [7], wherein the optical film has a thickness of 20 to 35 μm.

[9] A polarizing plate comprising a polarizer and the optical film according to any one of [1] to [8] disposed on at least one surface of the polarizer.
[10] A liquid crystal display device comprising a liquid crystal cell and a pair of polarizing plates sandwiching the liquid crystal cell, wherein at least one of the pair of polarizing plates is the polarizing plate according to [9]. Liquid crystal display device.
[11] The liquid crystal display device according to [10], wherein the liquid crystal cell is a VA liquid crystal cell.

  The optical film of the present invention exhibits reverse wavelength dispersion or flat wavelength dispersion and good durability. Thereby, the liquid crystal display device having the optical film of the present invention has a wide viewing angle and good durability.

It is a schematic diagram which shows the basic composition of one Embodiment of the liquid crystal display device which concerns on this invention.

1. Optical film The optical film of this invention contains the compound represented by General formula (1).

Compound represented by general formula (1) The compound represented by general formula (1) has the following structure.

Cyc in the general formula (1) represents a cyclic group containing a divalent 5-membered ring or 6-membered ring. The divalent 5-membered ring or 6-membered ring may be condensed with other rings. When a divalent 5-membered ring or 6-membered ring is condensed with another ring, only one 5-membered ring or 6-membered ring constituting the condensed ring is a connecting part to L ₁ and a connecting part to L ₂ And have. The cyclic group containing a divalent 5-membered ring or 6-membered ring can be a group derived from an aliphatic hydrocarbon ring, an aromatic hydrocarbon ring, a saturated heterocyclic ring or an unsaturated heterocyclic ring.

  Examples of groups derived from an aliphatic hydrocarbon ring include groups derived from cycloalkanes such as cyclopentane and cyclohexane; groups derived from cycloalkenes such as cyclopentadiene and cyclohexene. Examples of groups derived from an aromatic hydrocarbon ring include groups derived from benzene, naphthalene, anthracene, phenanthrene, pyrene, fluorene and the like. Examples of groups derived from saturated heterocycles include groups derived from pyrrolidine, piperidine and the like. Examples of groups derived from unsaturated heterocycles are derived from thiophene, furan, pyridine, furan, oxazole, imidazole, thiazole, benzothiophene, 1,3-benzodithiol, benzoxazole, benzimidazole, benzothiazole and the like. Group.

  Of these, a group derived from an unsaturated heterocycle is preferable, and a group derived from 1,3-benzodithiol, benzothiazole, benzoxazole, or benzimidazole is more preferable.

R _{3 in the} general formula (1) represents a hydrogen atom or a substituent bonded to the carbon atom constituting the cyclic group (Cyc). The substituent is not particularly limited,
Halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.); alkyl group (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group, etc.) Cycloalkyl group (cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.); alkenyl group (vinyl group, allyl group, etc.); cycloalkenyl group (2-cyclopenten-1-yl, 2-cyclohexene-1- Alkynyl group (ethynyl group, propargyl group, etc.); alkylidene group; aryl group (phenyl group, p-tolyl group, naphthyl group, etc.); heteroaryl group (2-furyl group, 2-thienyl group, 2) -Pyrimidinyl group, 2-benzothiazolyl group, etc.); alkyloxy group (methoxy group, ethoxy group, isopropyl group) Xyl group, tert-butoxy group, n-octyloxy group, 2-methoxyethoxy group, etc.); aryloxy group (phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2 -Tetradecanoylaminophenoxy group etc.); alkylcarbonyl group (acetyl group etc.); arylcarbonyl group (pivaloylbenzoyl group etc.); alkyloxycarbonyl group; aryloxycarbonyl group; alkylcarbonyloxy group (formyloxy group, Acetyloxy group, pivaloyloxy group, stearoyloxy group, etc.); arylcarbonyloxy group (benzoyloxy group, p-methoxyphenylcarbonyloxy group, etc.); alkylthio group (methylthio group, ethylthio group, n-hexadecylthio group, etc.); aryl O group (phenylthio group, p-chlorophenylthio group, m-methoxyphenylthio group, etc.); heteroarylthio group; arylsulfonyl group; amino group (amino group, methylamino group, dimethylamino group, anilino group, N-methyl group) -Anilino group, diphenylamino group, etc.); acylamino group (formylamino group, acetylamino group, pivaloylamino group, lauroylamino group, benzoylamino group, etc.); alkylsulfonylamino group (methylsulfonylamino group, butylsulfonylamino group, etc.) Arylsulfonylamino group (phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group, etc.); sulfamoyl group (N-ethylsulfamoyl group, N- (3-dodecyl); Oxypropyl) Sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N-benzoylsulfamoyl group, N- (N′phenylcarbamoyl) sulfamoyl group, etc.); carbamoyl group (carbamoyl group, N- Methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-octylcarbamoyl group, N- (methylsulfonyl) carbamoyl group, etc.); hydroxyl group; cyano group; nitro group; carboxyl group; sulfo group; A mercapto group; or a combination of two or more thereof. Examples of the group in which two or more of these are combined include a group in which a part of the alkyl group is substituted with a halogen atom, a hydroxyl group, an alkyloxy group, a cycloalkyl group, a phenyl group, or the like. A plurality of R ₃ may be bonded to each other to form a ring.

J of general formula (1) indicates the number of _{R 3} having the above-described cyclic group (Cyc). j represents an integer of 0 to 4, and is preferably 1. However, when j is 0, the aforementioned cyclic group is a condensed ring. In order to impart good wavelength dispersibility to the obtained film by the compound represented by the general formula (1), Cyc having (R ₃ ) j is the length of the compound represented by the general formula (1). This is because it is preferable to have a structure that generates a dipole moment in a direction substantially perpendicular to the chain direction (direction connecting L ₁ and L ₂ ).

Divalent 5-membered ring or 6-membered cyclic group containing a ring having R ₃ (a group represented in formula _{(1) -Cyc (R 3)} j- in) in order to enhance the chromatic dispersion of the resulting film It is preferable to have a structure represented by the general formula (2) or (3). In the following general formula (2) or (3),-* represents a connecting portion with L ₁ or L ₂ .

X ₁ and X _{2 in} the formula (2) each independently represent —S—, —O—, or —NRb— (Rb represents an alkyl group having 1 to 7 carbon atoms or a hydrogen atom), preferably — S- is shown. Examples of the alkyl group having 1 to 7 carbon atoms include a methyl group and an ethyl group.

R ₄ and R _{5 in} the formula (2) each independently represent a hydrogen atom or a substituent. The substituent is defined in the same manner as the substituent for R ₃ described above. Among them, R ₄ and R ₅ are each an alkyl group having 1 to 10 carbon atoms, an alkylcarbonyl group having 2 to 11 carbon atoms, an alkyloxycarbonyl group having 2 to 11 carbon atoms, an acylamino group, a cyano group, or a combination thereof. It is preferably a group. Among these, the alkyl group contained in a group other than the cyano group may further have a substituent such as an alkyloxy group, a cycloalkyl group, or an aryl group.

X _{3 in the} formula (3) represents —S—, —O— or —NRb— (Rb represents an alkyl group having 1 to 7 carbon atoms or a hydrogen atom), preferably —S— or —O—. Indicates.

R _{6 in} formula (3) represents a hydrogen atom or a substituent. The substituent is defined in the same manner as the substituent for R ₃ described above. Among them, R ₆ is a cycloalkyl group having 5 or 6 ring carbon atoms, an alkenyl group having 2 to 11 carbon atoms, an alkynyl group having 2 to 11 carbon atoms, an aryl group, an aryloxy group, an arylcarbonyl group, an arylthio group, It is preferably a heteroarylthio group, an amino group, an arylsulfonyl group, or a group obtained by combining two or more thereof. These groups may further have a substituent such as a cyano group, an alkyloxy group, an alkylthio group, an alkylcarbonyl group, an aryl group, and a heteroaryl group.

Specific examples of the cyclic group containing a divalent 5-membered ring or 6-membered ring having R ₃ are shown below. First, the specific example of the cyclic group which has a structure represented by Formula (2) is shown.

Next, the specific example of the cyclic group which has a structure represented by Formula (3) is shown.

Specific examples of other cyclic groups are shown.

L ₁ and L _{2 in} the general formula (1) are each independently a single bond, —O—, —CO—, —NRa— (Ra is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom), —S -, - SO ₂ - or -CH ₂ - indicates, preferably -O-.

Str ₁ and Str _{2 in} the general formula (1) each independently represent a steroid residue. The residues of steroids include a steroid nucleus (cyclopentano-perhydrophenanthrene nucleus) and an optional linking group (including a single bond) with L ₁ or L ₂ .

Any carbon atom of the steroid nucleus contained in the steroid residue and L ₁ or L ₂ may be bonded directly or via a linking group, but the orientation of the compound represented by the general formula (1) In order to enhance the properties, it is preferable that the carbon atom at the 3rd or 17th position of the steroid nucleus and L ₁ or L ₂ are bonded directly or via a linking group.

Examples of the linking group that links the carbon atom of the steroid nucleus contained in the steroid residue to L ₁ or L ₂ include an alkylcarbonyl group (—R—C (═O) —), a carbonylalkyl group (— C (= O) -R-), an aminocarbonyl group (-C (= O) -NR-) and the like. The alkyl moiety in the alkylcarbonyl group, carbonylalkyl group, and aminocarbonyl group preferably has 1 to 5 carbon atoms.

R ₁ and R _{2 in} the general formula (1) are substituents bonded to the carbon atom of the steroid nucleus. The substituent is not particularly limited, but is a halogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, alkyloxy group, alkylcarbonyl group, ester group (alkyloxycarbonyl group, alkylcarbonyloxy group), formyl group, alkylene It may be a group in which an ester group is bonded via a group.

The alkyl moiety in the alkyl group, alkyloxy group, alkyloxycarbonyl group, and alkylcarbonyloxy group may contain an oxyalkylene group or a polyoxyalkylene group. The polyoxyalkylene group is a group containing oxyalkylene as a repeating unit, and includes “CH ₃ — (OCH ₂ CH ₂ ) n—” containing an oxyethylene unit and “CH ₃ — (OCH () containing an oxypropylene unit. -CH _{3) CH} 2) m- ", and others.

  The alkyl moiety in the alkyl group, alkyloxy group, alkyloxycarbonyl group and alkylcarbonyloxy group may be linear or branched, but is preferably linear. It is preferable that carbon number of an alkyl part is 1-15, and in order to improve the orientation of the compound represented by General formula (1), it is preferable that it is 4-10.

Among these, in order to increase the orientation of the compound represented by the general formula (1), R ₁ and R ₂ are preferably long-chain alkyl groups, and are preferably alkyl groups having 4 to 8 carbon atoms. In order to increase the hydrophilicity of the compound represented by the general formula (1) and increase the compatibility with the cellulose ester, R ₁ and R ₂ are preferably an alkyl group containing a polyoxyalkyl group.

R ₁ and R ₂ may be bonded to any carbon atom of the steroid nucleus, but bonded to the carbon atom at the 2-position, 3-position, 4-position, 15-position, 16-position or 17-position of the steroid nucleus. It is preferable that it is bonded to a carbon atom at the 3rd or 17th position. This is because the compound represented by the general formula (1) in which R ₁ and R ₂ are bonded at the above-described substitution positions becomes a rod-like compound and has high orientation.

M and n in the general formula (1) represent the number of substituents R ₁ and R ₂ . m and n each independently represent an integer of 0 to 10, preferably 0 or 1.

(R ₁ ) m-Str- or (R ₂ ) n-Str ₂ -can be derived from steroids. Steroids are compounds containing a steroid nucleus (cyclopentano-perhydrophenanthrene nucleus). Steroids are classified into five types: estrane, androstane, pregnane, cholan, and cholestane, depending on the type of side chain that binds to the steroid nucleus.

  Examples of estrane include β-estradiol, estradiol benzoate, estriol, estrone, ethinyl estradiol, mestranol and the like.

  Examples of androstane include adrenosterone, 1,4-androstadiene-3,17-dione, delta 4-androstene-3,17-dione, androsterone, dehydroepiandrosterone, dehydroepiandrosterone acetate Epiandrosterone (derived from wool oil), 17β-hydroxy-17-methylandrost-1,4-dien-3-one, 1α-methylandrostane-17β-ol-3-one, 17α-methylandrostane- 17β-ol-3-one, methylandrostenediol, methyltestosterone, delta 9 (11) -methyltestosterone, oxymetholone, dehydroepiandrosterone-3-sulfate sodium salt hydrate (Sodium Dehydroepiandrosterone-3-sulfate Hydrate), Stanolon, Star Zororu, testosterone, and the like testosterone propionate.

  Examples of pregnane include 16,17-epoxypregnenolone acetate, 16,17-epoxyprogesterone, fluorometholone, 11α-hydroxyprogesterone, 11α-hydroxyprogesterone acetate, 17α-hydroxyprogesterone caproate, megestrol acetate, 5β- Pregnane-3α, 20α-diol, 4-pregnene-3,11,20-trione, pregnenolone, pregnenolone acetate, progesterone, cortisone and the like are included.

  Examples of cholan include chenodeoxycholic acid, 3-[(3-cholamidopropyl) dimethylammonio] -1-propanesulfonate, cholic acid, dehydrocholic acid, deoxycholic acid, 3β-hydroxy-delta 5-cholenoic acid, 3α-Hydroxy-DELTA5-cholenic acid, 3α-hydroxy-7-oxo-5β-cholanic acid, hyodeoxycholic acid, lithocholic acid, methyl cholate, methyl hyodeoxycholic acid 12-oxochenodeoxycholic acid, Tauroursodeoxycholic Acid Dihydrate, ursodeoxycholic acid and the like.

  Examples of cholestane include β-cholestanol, (+)-4-cholesten-3-one, cholesterol, cholesterol-5α, 6α-epoxide, ergosterol, β-sitosterol, β-sitosterol, stigmasterol, diosgenin Etc. are included.

The steroid which becomes (R ₁ ) m-Str- or (R ₂ ) n-Str ₂ -is preferably chorane or cholestane. Coran or cholestane has a relatively long side chain bonded to the 17th carbon atom of the steroid nucleus among steroids, and the compound represented by the general formula (1) containing it is likely to be a rod-like compound and has an orientation property. Because it is expensive. Cholan is preferably a cholic acid derivative. The cholic acid derivative is a compound in which a pentanoic acid group or an ester thereof is bonded to position 17 of the steroid nucleus, and is preferably dehydrocholic acid or lithocholic acid. Cholestan is preferably a cholesterol derivative. The cholesterol derivative is a compound in which a 1,5-dimethylhexyl group is bonded to the 17th position of the steroid nucleus, and preferably cholesterol.

Specific examples of the compound represented by the general formula (1) are shown below.

  The reason why the compound represented by the general formula (1) can impart reverse wavelength dispersion of retardation in the in-plane direction to the optical film is not necessarily clear, but is presumed as follows. That is, the compound represented by the general formula (1) has a steroid residue. Since the steroid residue has a highly sterically controlled steroid nucleus, it can impart flat wavelength dispersion or reverse wavelength dispersion to the optical film. Further, the compound represented by the general formula (1) is not necessarily clear, but the side chain of the highly sterically controlled steroid is easily entangled with the side chain of the oriented cellulose ester, so that it is compatible with the cellulose ester. Is also expected to improve. In addition, the compatibility of the compound represented by the general formula (1) with the cellulose ester can be easily adjusted according to the type of side chain bonded to the steroid nucleus described in the present invention. Thereby, the film containing the compound represented by the general formula (1) has good bleed-out resistance and resistance to an alkaline saponification solution.

The compound represented by the general formula (1) can be synthesized by a known synthesis method, for example, a method described in JP 2010-163483 A or the like. For example, compound DDS-13 can be synthesized according to the following scheme.

  The synthesis of Compound 4 is described in “Journal of Chemical Crystallography” (1997); 27 (9); p.515-526. It can be performed with reference to the method described in 1. In more detail, it can be synthesized by the method described in JP-A-2008-107767, paragraphs 0066 to 0067 and 0136 to 0176.

  On the other hand, the carboxyl group of lithocholic acid 5 is heated and stirred in tert-butanol in the presence of a concentrated sulfuric acid catalyst to be esterified to obtain compound 6. After replacing the hydrogen atom of the hydroxyl group of the obtained compound 6 with a hexyl group by Williamson ether synthesis, the tert-butyl ester moiety of compound 6 is hydrolyzed with a trifluoroacetic acid catalyst and deprotected to give compound 7 Get. Compound 7 is acid chloride using thionyl chloride, and then reacted with compound 4 to obtain DDS-13.

Compound DDS-10 can be synthesized according to the following scheme.

  The compound 15 can be synthesized with reference to JP 2010-31223 A.

  The phenolic hydroxyl group of estradiol 16 is anionized under basic conditions, reacted with compound 19 and etherified to give compound 17. Subsequently, the remaining hydroxyl group is mesylated to obtain compound 18. Then, DDS-10 can be obtained by anionizing compound 15 and reacting with compound 18.

  The content of the compound represented by the general formula (1) is 1 to 15 with respect to the cellulose ester in order to sufficiently impart reverse wavelength dispersion to the optical film without impairing the mechanical strength of the optical film. It is preferable that it is mass%, and it is more preferable that it is 2-10 mass%.

  The optical film of the present invention preferably further contains a cellulose ester in addition to the compound represented by the general formula (1).

Cellulose ester The cellulose ester is not particularly limited, but may be a compound obtained by esterifying cellulose with an aliphatic carboxylic acid or aromatic carboxylic acid having about 2 to 22 carbon atoms. The aliphatic carboxylic acid may be a linear or branched aliphatic carboxylic acid, may have a ring, and may further have a substituent. The cellulose ester is more preferably a compound obtained by esterifying cellulose with a lower fatty acid having 6 or less carbon atoms.

  Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate and the like.

  The cellulose ester preferably has a total acyl group substitution degree of 2.0 or more and 3.0 or less, and 2.4 or more in order to enhance the compatibility with the compound represented by the general formula (1) described later. More preferably, it is 3.0 or less.

More preferably, the cellulose ester satisfies the following formulas (a) and (b) at the same time.
Formula (a) 2.4 ≦ X + Y ≦ 3.0
Formula (b) 0 ≦ Y ≦ 1.5
(Wherein, X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the propionyl group or butyryl group, or a mixture thereof)

Of these, cellulose acetate (Y = 0) and cellulose acetate propionate (Y> 0 and Y: propionyl group) are preferable. The cellulose acetate propionate more preferably satisfies the following formulas (a), (b1) and (c1) at the same time.
Formula (a) 2.4 ≦ X + Y ≦ 3.0
Formula (b1) 0.1 ≦ Y ≦ 1.5
Formula (c1) 1.0 ≦ X ≦ 2.4

  The acyl group substitution degree of cellulose ester can be measured according to ASTM-D817-96.

  The cellulose ester may be a mixture of a plurality of types of cellulose esters having different degrees of substitution in order to obtain desired optical properties. The mixing ratio in a mixture of two types of cellulose esters having different degrees of substitution is preferably 10:90 to 90:10 by mass ratio.

In order to obtain a film having high mechanical strength, the number average molecular weight of the cellulose ester is preferably in the range of 6.0 × 10 ^{4 to} 3.0 × 10 ⁵ , and 7.0 × 10 ⁴ to 2. The range of 0 × 10 ⁵ is more preferable. The number average molecular weight of the cellulose ester can be measured by gel permeation chromatography (GPC).

The measurement conditions are as follows.
Solvent: Methylene chloride Column: Three Shodex K806, K805, K803G (manufactured by Showa Denko KK) are connected and used.
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 1.0 × 10 ^{6 to} 5.0 × 10 ² 13 calibration curves are used. The 13 samples are preferably selected at approximately equal intervals.

  Cellulose esters can be synthesized by known methods. Specifically, cellulose can be synthesized by an esterification reaction between cellulose and an organic acid having at least 3 carbon atoms containing at least acetic acid or acetic anhydride (Japanese Patent Laid-Open No. 10-45804). See the description method).

  As the raw material cellulose, for example, cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf and the like can be used. The cellulose used as a raw material may be only one type or a mixture of two or more types.

  The optical film of the present invention may further contain an optional component. Examples of optional components include resins other than cellulose esters, sugar ester compounds, plasticizers, ultraviolet absorbers, antioxidants, retardation control agents, and fine particles.

Resins other than cellulose esters Examples of resins that can be used in combination with cellulose esters include polycarbonate resins, polystyrene resins, polysulfone resins, polyester resins, polyarylate resins, acrylic resins, olefin resins (norbornene resins, Cyclic olefin-based resin, cyclic conjugated diene-based resin, vinyl alicyclic hydrocarbon-based resin, etc.), among others, at least one of polycarbonate-based resin, acrylic-based resin, and cyclic olefin-based resin. It is preferable that content of resin other than a cellulose ester is 5-70 mass% with respect to a cellulose ester.

Sugar ester compound The sugar ester compound contained in the optical film of the present invention is a compound obtained by esterifying a hydroxyl group contained in sugar and a monocarboxylic acid.

  The sugar constituting the sugar ester compound is preferably a compound in which at least one of the furanose structure and the pyranose structure is bonded to 1 or more and 12 or less.

Examples of the sugar constituting the sugar ester compound include monosaccharides such as glucose, galactose, mannose, fructose, xylose and arabinose; disaccharides such as lactose, sucrose, maltitol, lactitol, lactulose, cellobiose, maltose, and gentiobiose;
Contains trisaccharides such as cellotriose, maltotriose, raffinose, kestose, gentiotriose, and xylotriose; polysaccharides with more than tetrasaccharides such as nystose, 1F-fructosylnystose, stachyose, gentiotetraose, galactosyl sucrose, etc. It is. Examples of sugars constituting the sugar ester compound include oligosaccharides such as maltooligosaccharide, isomaltooligosaccharide, fructooligosaccharide, galactooligosaccharide, and xylo-oligosaccharide. These oligosaccharides are produced by allowing an enzyme such as amylase to act on starch or sucrose.

  Of these, sugars having both a pyranose structure and a furanose structure are preferable, sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose and the like are more preferable, and sucrose is more preferable.

  The monocarboxylic acid constituting the sugar ester compound is not particularly limited, and may be a known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, or aromatic monocarboxylic acid. In order to easily develop the retardation of the film, an aromatic monocarboxylic acid is preferable. The monocarboxylic acid may be one kind or a mixture of two or more kinds. For example, an aliphatic monocarboxylic acid and an aromatic monocarboxylic acid may be combined.

  Examples of aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid Saturated fatty acids such as acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid Unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, octenoic acid and the like are included.

  Examples of the alicyclic monocarboxylic acid include acetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, and cyclooctanecarboxylic acid.

  The aromatic monocarboxylic acid is a monocarboxylic acid having one or more benzene rings, and the benzene ring may further have a substituent such as an alkyl group or an alkoxy group. Examples of aromatic monocarboxylic acids include benzoic acid, xylic acid, hemelitic acid, mesitylene acid, prenicylic acid, γ-isoduric acid, jurylic acid, mesitonic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropa Acid, atropic acid, hydrocinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid, creosote acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyrocatechuic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratromic acid, o-veratrumic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratrumic acid, o-homoveratrumic acid, phthalonic acid, p-coumaric acid, etc. Among them, benzoic acid is particularly preferable.

  It is preferable that 70% or more of the hydroxyl groups contained in the constituent sugar having a pyranose structure or furanose structure are esterified with a monocarboxylic acid.

  Examples of the sugar ester compound include, but are not limited to, Monopet SB manufactured by Daiichi Kogyo Seiyaku Co., Ltd. and Monopet SOA manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

  The content of the sugar ester compound is preferably 0.5 to 30% by mass and more preferably 5 to 20% by mass with respect to the cellulose ester.

Plasticizer Examples of plasticizers include polyester plasticizers, polyhydric alcohol ester plasticizers, polycarboxylic acid ester plasticizers (including phthalate ester plasticizers), glycolate plasticizers, ester plasticizers. Agents (including fatty acid ester plasticizers) and acrylic plasticizers are preferred. These may be used alone or in combination of two or more.

Polyester Plasticizer The polyester plasticizer is preferably a compound represented by the following general formula (4).
General formula (4)

  In formula (4), A represents a divalent group derived from an alkylene dicarboxylic acid having 4 to 12 carbon atoms or a divalent group derived from an aryl dicarboxylic acid having 8 to 14 carbon atoms. G is a divalent group derived from an alkylene glycol having 2 to 12 carbon atoms, a divalent group derived from an aryl glycol having 6 to 12 carbon atoms, or an oxyalkylene having 4 to 12 carbon atoms. Represents a divalent group derived from glycol. B represents a monovalent group derived from a hydrogen atom or a monocarboxylic acid. n represents an integer of 1 or more.

  Examples of the divalent group of A derived from an alkylene dicarboxylic acid having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid And divalent groups derived from the above. Examples of divalent groups derived from aryl dicarboxylic acids having 8 to 14 carbon atoms in A include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, etc. A divalent group derived from is included.

  Examples of the divalent group of G derived from an alkylene glycol having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, , 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-didiol) Methylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2- Methyl-1,8-octanediol, 1, - nonanediol, include divalent groups derived from 1,10-decanediol, and 1,12-octadecanediol like.

  Examples of the divalent group of G derived from an aryl glycol having 6 to 12 carbon atoms include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), and 1,4-dihydroxy. Divalent groups derived from benzene (hydroquinone) and the like are included. Examples of the divalent group derived from oxyalkylene glycol having 4 to 12 carbon atoms in G are derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. Divalent groups are included.

  G is preferably a divalent group derived from an alkylene glycol having 2 to 12 carbon atoms. This is to increase the compatibility of the polyester plasticizer with the cellulose ester.

  Examples of the monovalent group of B derived from monocarboxylic acid include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, and normal propyl benzoic acid. Monovalent groups derived from, for example, aromatic monocarboxylic acids such as aminobenzoic acid, and acetoxybenzoic acid; aliphatic monocarboxylic acids such as acetic acid, propionic acid, and butyric acid.

  The number average molecular weight of the polyester plasticizer is preferably 300 to 1500, and more preferably 400 to 1000. A polyester plasticizer having a number average molecular weight of less than 300 may be easily eluted from the optical film.

  The acid value of the polyester-based plasticizer is preferably 0.5 mgKOH / g or less from the viewpoint of enhancing the adhesion between the optical film containing the plasticizer and another functional layer such as a hard coat layer, and the like. / G or less is more preferable. The acid value of the polyester plasticizer is defined as the number of milligrams of potassium hydroxide required to neutralize the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value of the polyester plasticizer can be measured according to JIS K0070.

  The hydroxyl value of the polyester plasticizer is preferably 25 mgKOH / g or less, and more preferably 15 mgKOH / g or less, from the viewpoint of enhancing the compatibility with the cellulose ester. The hydroxyl value of the polyester plasticizer is defined as the number of milligrams of potassium hydroxide required to neutralize unreacted acetic acid when 1 g of a sample is reacted with acetic anhydride and acetylated. The hydroxyl value of the polyester plasticizer can be measured according to JIS K 0070 (1992).

Specific examples of the polyester plasticizer represented by the formula (4) are shown below.

Polyhydric alcohol ester plasticizer The polyhydric alcohol ester plasticizer is an ester compound (alcohol ester) of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, preferably a 2-20 valent aliphatic. It is a polyhydric alcohol ester. The polyhydric alcohol ester compound preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  Preferred examples of the aliphatic polyhydric alcohol include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol , Galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol and the like are preferable.

  The monocarboxylic acid is not particularly limited, and may be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, an aromatic monocarboxylic acid, or the like. In order to increase the moisture permeability of the film and make it less likely to volatilize, an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferred. One type of monocarboxylic acid may be sufficient and a 2 or more types of mixture may be sufficient as it. Further, all of the OH groups contained in the aliphatic polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  The aliphatic monocarboxylic acid is preferably a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms. The carbon number of the aliphatic monocarboxylic acid is more preferably 1-20, and still more preferably 1-10. Examples of such aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid; Examples include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Especially, in order to improve compatibility with a cellulose ester, the mixture of an acetic acid or an acetic acid and another monocarboxylic acid is preferable.

  Examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid and the like.

  Examples of aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as an alkyl group, a methoxy group or an ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid or toluic acid; biphenylcarboxylic acid, naphthalene Aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralincarboxylic acid are included, and benzoic acid is preferable.

  The molecular weight of the polyhydric alcohol ester plasticizer is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. In order to make it difficult to volatilize, a higher molecular weight is preferable; in order to improve moisture permeability and compatibility with cellulose ester, a lower molecular weight is preferable.

Polyvalent carboxylic ester plasticizer The polyvalent carboxylic ester plasticizer is an ester compound of a divalent or higher, preferably 2-20 valent polycarboxylic acid and an alcohol compound. The polyvalent carboxylic acid is preferably a 2-20 valent aliphatic polyvalent carboxylic acid, or a 3-20 valent aromatic polyvalent carboxylic acid or a 3-20 valent alicyclic polyvalent carboxylic acid. .

  Preferred examples of the polyvalent carboxylic acid include trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid; succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid Aliphatic polycarboxylic acids such as maleic acid and tetrahydrophthalic acid; oxypolyvalent carboxylic acids such as tartaric acid, tartronic acid, malic acid and citric acid are included. Carboxylic acid.

  Examples of alcohol compounds include known alcohol compounds and phenol compounds. Examples of the alcohol compound include linear or branched aliphatic saturated alcohols or aliphatic unsaturated alcohols having 1 to 32 carbon atoms, more preferably 1 to 20 carbon atoms, and still more preferably 1 to 10 carbon atoms; Examples include alicyclic alcohol compounds such as pentanol and cyclohexanol; aromatic alcohol compounds such as benzyl alcohol and cinnamyl alcohol. The alcohol compound may be one kind or a mixture of two or more kinds.

  In the oxypolycarboxylic acid as the polyvalent carboxylic acid, an alcoholic or phenolic hydroxyl group may be esterified with a monocarboxylic acid. The monocarboxylic acid used for esterification can be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, or an aromatic monocarboxylic acid.

  The aliphatic monocarboxylic acid includes a linear or branched fatty acid having 1 to 32 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Examples of such aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid. Saturated fatty acids such as acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid An unsaturated fatty acid such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and the like;

  Examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid and the like. Examples of aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid Aromatic monocarboxylic acids and the like are included. Of these, acetic acid, propionic acid, and benzoic acid are particularly preferable.

  The molecular weight of the polycarboxylic acid ester plasticizer is not particularly limited, but is preferably 300 to 1000, and more preferably 350 to 750. The molecular weight of the polyvalent carboxylic acid ester plasticizer is preferably larger from the viewpoint of suppressing bleed-out; it is preferably smaller from the viewpoint of moisture permeability and compatibility with the cellulose ester.

  The acid value of the polyvalent carboxylic acid ester plasticizer is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. It is preferable to set the acid value within the above range because retardation fluctuations in the retardation are also suppressed.

  The acid value of the polyvalent carboxylic ester plasticizer is defined as the number of milligrams of potassium hydroxide required to neutralize the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value can be measured according to JIS K0070.

  Examples of polycarboxylic acid ester plasticizers include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl triphenyl citrate. Benzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like are included.

  The polyvalent carboxylic acid ester plasticizer may be a phthalic acid ester plasticizer. Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate and the like.

  Examples of glycolate plasticizers include alkylphthalyl alkyl glycolates. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl Glycolate, and the like are included.

  The ester plasticizer includes a fatty acid ester plasticizer, a citrate ester plasticizer, a phosphate ester plasticizer, and the like.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate. Examples of the citrate plasticizer include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate. Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.

Acrylic plasticizer Acrylic plasticizer includes at least an ethylenically unsaturated monomer Xa that does not have both an aromatic ring and a hydroxyl group in the molecule, and an ethylenically unsaturated monomer Xb that does not have an aromatic ring in the molecule and has a hydroxyl group. And a polymer Y having an ethylenically unsaturated monomer Ya having no aromatic ring in the molecule as a polymerization component. The ethylenically unsaturated monomer is preferably a (meth) acrylic acid ester.

The polymer X preferably has a structure represented by the following general formula (X). The following formula _{(X) - [CH 2 -C} (-Rc) (- CO 2 Rd)] m- is a group derived from an ethylenically unsaturated monomer _{Xa; - [CH 2 -C (} -Re ) (— CO ₂ Rf—OH) —] n— is a group derived from the ethylenically unsaturated monomer Xb.
Formula (X)
_{- [CH 2 -C (-Rc)} (- CO 2 Rd)] m- [CH 2 -C (-Re) (- CO 2 Rf-OH) -] n- [Xc] p-

  Rc and Re in the formula (X) represent a hydrogen atom or a methyl group. Rd represents an alkylene group having 1 to 12 carbon atoms or a cycloalkylene group. Rf represents a methylene group, an ethylene group or a propylene group. Xc represents a monomer unit polymerizable to Xa and Xb. m, n and p represent molar composition ratios. However, m and n are not 0, and m + n + p = 100. The weight average molecular weight of the polymer X is preferably 3000 to 30000.

The polymer Y preferably has a structure represented by the following general formula (Y). The following formula _{(Y) - [CH 2 -C} (-Rg) (- CO 2 Rh-OH) -] k- is a group derived from an ethylenically unsaturated monomer Ya.
General formula (Y)
_{Ry- [CH 2 -C (-Rg)} (- CO 2 Rh-OH) -] k- [Yb] q-

  Rg in the formula (Y) represents a hydrogen atom or a methyl group. Rh represents a methylene group, an ethylene group or a propylene group. Ry represents a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 3 carbon atoms. Yb represents a monomer unit copolymerizable with Ya. k and q represent a molar composition ratio. However, k is not 0 and k + q = 100. The weight average molecular weight of the polymer Y is preferably 500 or more and 3000 or less.

  The total content of these plasticizers is preferably 0.5 to 30% by mass and more preferably 5 to 20% by mass with respect to the cellulose ester.

Retardation Control Agent The optical film of the present invention may further contain a retardation control agent in order to improve the liquid crystal display quality. The retardation control agent includes an aromatic compound having two or more aromatic rings as described in European Patent No. 911656A2, a rod-shaped compound described in JP-A-2006-2025, and the like. One type of retardation control agent may be sufficient, and a 2 or more types of mixture may be sufficient as it.

  The aromatic ring contained in the aromatic compound includes an aromatic hydrocarbon ring and an aromatic heterocycle, and is preferably an aromatic heterocycle. As a preferred example of the aromatic heterocycle, a 1,3,5-triazine ring is particularly preferred.

  It is preferable that it is 0.5-20 mass% with respect to the resin component contained in an optical film, and, as for content of a retardation control agent, it is more preferable that it is 1-10 mass%.

Ultraviolet Absorber The optical film of the present invention may further contain an ultraviolet absorber in order to improve the durability of the optical film. The ultraviolet absorber is a compound that absorbs ultraviolet rays having a wavelength of 400 nm or less, preferably a compound having a transmittance at a wavelength of 370 nm of 10% or less, more preferably 5% or less, and even more preferably 2% or less.

  Examples of ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, etc. Is a benzotriazole ultraviolet absorber, a benzophenone ultraviolet absorber, or a triazine ultraviolet absorber, more preferably a benzotriazole ultraviolet absorber or a benzophenone ultraviolet absorber.

  Specific examples of the ultraviolet absorber include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl)- In addition to 6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., commercially available products Tinobine 109 and Tinuvin manufactured by BASF Japan 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928 and the like are included. These ultraviolet absorbers may be only one kind or a mixture of two or more kinds.

  In addition to these, polymer ultraviolet absorbers and discotic compounds are also preferably used as ultraviolet absorbers. Examples of polymer ultraviolet absorbers include polymer type ultraviolet absorbers described in JP-A-6-148430; examples of discotic compounds include compounds having a 1,3,5-triazine ring. It is.

  Although content of a ultraviolet absorber is based also on the kind of ultraviolet absorber, etc., it is preferable that it is 0.5-10 mass% with respect to the whole optical film, and it is more preferable that it is 0.6-4 mass%. preferable.

Antioxidant The optical film of the present invention may further contain an antioxidant, for example, in order to prevent deterioration of the optical film that is likely to occur under high humidity and high temperature. The antioxidant has a function of delaying or preventing the decomposition of the residual solvent amount in the optical film by halogen or phosphoric acid based plasticizer.

  The antioxidant is preferably a hindered phenol compound, and specific examples thereof include 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-oxide). -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl- -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1, 3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl)- Isocyanurate and the like are included. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred.

  These compounds include, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, tris (2,4 It may be used in combination with a phosphorus processing stabilizer such as -di-t-butylphenyl) phosphite.

  The content of the antioxidant is preferably 1 ppm to 1.0% by mass ratio with respect to the cellulose ester, and more preferably 10 to 1000 ppm.

Fine particles The optical film of the present invention may further contain fine particles in order to improve slipperiness. The fine particles may be inorganic fine particles or organic fine particles.

  Examples of inorganic fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate And calcium phosphate. Examples of organic fine particles include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, melamine Resin, polyolefin powder, polyester resin, polyamide resin, polyimide resin, polyfluorinated ethylene resin, pulverized classification of organic polymer compounds such as starch, polymer compound synthesized by suspension polymerization method, spray High molecular compounds made spherical by a dry method or a dispersion method are included. In order to reduce the increase in the haze of the film, fine particles containing silicon are preferable, and silicon dioxide is particularly preferable.

  Examples of the silicon dioxide fine particles include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (commercially available from Nippon Aerosil Co., Ltd.). Of these, Aerosil 200V and Aerosil R972V are preferred because of the great effect of reducing the coefficient of friction while keeping the haze of the optical film low.

  The primary average particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. The fine particles are preferably contained in the optical film so that the dynamic friction coefficient of at least one surface of the optical film is 0.2 to 1.0. The content of the fine particles is preferably 0.01 to 1% by mass and more preferably 0.05 to 0.5% by mass with respect to the optical film.

  The thickness of the optical film is not particularly limited, but is preferably 10 to 200 μm, more preferably 10 to 100 μm, further preferably 20 to 60 μm, and particularly preferably 20 to 35 μm. . If the thickness of the optical film is too large, the variation in retardation tends to increase due to humidity. On the other hand, if the thickness of the film is too small, it is difficult to obtain a desired retardation.

When the optical film of the present invention is used as an optical compensation film, the retardation Ro in the in-plane direction measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH is 20 to 100 nm. Is preferable, and it is more preferable that it is 40-100 nm. The retardation Rth in the thickness direction is preferably 70 to 300 nm, and more preferably 100 to 300 nm. The retardations _R0 and Rth of the optical film can usually be adjusted by stretching conditions.

The in-plane direction retardation R ₀ and the thickness direction retardation Rth are each expressed by the following equations.
Formula (I) R ₀ = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx: refractive index in the slow axis direction in the film plane, ny: refractive index in the direction perpendicular to the slow axis in the film plane, nz: refractive index of the film in the thickness direction, d: film thickness (Nm))

The retardations _R0 and Rth can be determined by the following method, for example.
1) The average refractive index of the film is measured with a refractometer.
2) The retardation _R0 in the in-plane direction when light having a wavelength of 590 nm from the normal direction of the film is incident is measured by KOBRA-21ADH manufactured by Oji Scientific Instruments.
3) The retardation value R (θ) when light having a wavelength of 590 nm is incident from the angle θ (incident angle (θ)) with respect to the film normal direction is measured by KOBRA-21ADH manufactured by Oji Scientific Instruments. . θ is larger than 0 °, preferably 30 ° to 50 °.
4) From the measured R ₀ and R (θ) and the above-described average refractive index and film thickness, nx, ny and nz are calculated by KOBRA-21ADH manufactured by Oji Scientific Instruments, and Rth is calculated. The measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.

The optical film of the present invention preferably has a wavelength dispersion characteristic DSP represented by the following formula of 1 or less, more preferably less than 1. This is because an optical film having a wavelength dispersion characteristic DSP of 1 or less exhibits a certain retardation in a wide wavelength region and can optically compensate.
DSP = Ro (450) / Ro (630)

The measurement of the wavelength dispersion characteristic Ro (450) / Ro (630) is performed by measuring the retardation using the KOBRA-21ADH manufactured by Oji Scientific Instruments Co., Ltd., and measuring the retardation Ro in the in-plane direction measured with light having a wavelength of 450 nm. (450) and retardation Ro (630) in the in-plane direction measured with light having a wavelength of 630 nm can be measured and applied to the following formulas.
DSP = Ro (450) / Ro (630)

  The haze of the optical film measured in accordance with JIS K-7136 is preferably less than 1%, and more preferably 0.1% or less.

The moisture permeability of the optical film at 40 ° C. and 90% RH measured in accordance with JIS Z 0208 is preferably 10 to 1200 g / m ² · 24 h. In order to reduce the moisture permeability of the optical film, for example, the total acyl group substitution degree of the cellulose ester contained in the optical film is increased, the ratio of the acyl group substitution degree of 3 or more carbon atoms is increased, a plasticizer, etc. A large amount of the additive may be contained.

  The visible light transmittance of the optical film of the present invention is preferably 90% or more, and more preferably 93% or more. The breaking elongation of the optical film of the present invention is preferably 10 to 80%.

  Since the optical film of the present invention contains the compound represented by the general formula (1), it exhibits flat wavelength dispersion or reverse wavelength dispersion. As a result, a constant retardation value in the in-plane direction is shown for light in a wide wavelength region, so that optical compensation can be made satisfactorily.

  The optical film of the present invention is used as a functional film for various display devices such as a liquid crystal display, a plasma display, and an organic EL display. Specifically, the optical film of the present invention is a polarizing plate protective film, a retardation film, an antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, or a viewing angle expansion liquid crystal display device. It is used as an optical compensation film or the like, and is particularly preferably used as a polarizing plate protective film, a retardation film or an optical compensation film. The retardation film made of the optical film of the present invention preferably has a function as a polarizing plate protective film.

2. Method for Producing Optical Film The optical film of the present invention can be produced through a step of obtaining a resin composition containing the cellulose ester described above and a step of forming the resin composition into an optical film. Examples of the method for molding the resin composition include a solution casting method and a melt casting method, but the solution casting method is preferable from the viewpoint of obtaining a thin film with high flatness. .

  The step of producing the optical film of the present invention by the solution casting method is 1) a step of preparing a dope (resin composition) by dissolving at least the above cellulose ester and, if necessary, a plasticizer in a solvent, ) A step of casting the dope onto an endless metal support, 3) a step of drying the cast dope to form a web, 4) a step of peeling the web from the metal support, and 5) stretching the web to form a film. 6) a step of further drying the film, and 7) a step of winding up the obtained film.

1) Process for preparing dope The dope is prepared by dissolving the above cellulose ester and, if necessary, an additive in a solvent. The concentration of the cellulose ester contained in the dope is preferably high in order to reduce the drying load. However, if the concentration of the cellulose ester is too high, it is difficult to filter, and the filtration accuracy tends to decrease. For this reason, it is preferable that the density | concentration of the cellulose ester contained in dope is 10-35 mass%, and it is more preferable that it is 15-25 mass%.

  The solvent contained in the dope may be one kind or a combination of two or more kinds. From the viewpoint of increasing production efficiency, it is preferable to use a combination of a good solvent and a poor solvent for cellulose ester. A good solvent refers to a solvent that dissolves cellulose ester alone, and a poor solvent refers to a solvent that swells cellulose or does not dissolve alone. Therefore, the good solvent and the poor solvent differ depending on the average acyl group substitution degree (acetyl group substitution degree) of the cellulose ester.

  When a good solvent and a poor solvent are used in combination, it is preferable that the good solvent is more than the poor solvent in order to increase the solubility of the cellulose ester. The mixing ratio of the good solvent and the poor solvent is preferably 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent.

  Examples of the good solvent include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate, and preferably methylene chloride or methyl acetate. Examples of the poor solvent include methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like. The dope preferably contains 0.01 to 2% by mass of water.

  The method of dissolving the cellulose ester in the solvent may be a general method, for example, a method of dissolving under heating and pressure, a poor solvent added to the cellulose ester to swell, and then adding a good solvent to dissolve. It can be a method. Especially, since it can heat beyond the boiling point in a normal pressure, the method of making it melt | dissolve under a heating and pressurization is preferable. Specifically, when stirring and dissolving while heating to a temperature in the range where the solvent is boiling or higher under normal pressure and the solvent does not boil under pressure, the generation of bulk undissolved material called gel or mamako can be suppressed.

  The pressurization can be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature is preferably higher from the viewpoint of increasing the solubility of the cellulose ester, but if it is too high, the pressure needs to be increased, and the productivity is lowered. For this reason, it is preferable that heating temperature is 45-120 degreeC, 60-110 degreeC is more preferable, and it is further more preferable that it is 70-105 degreeC. The pressure is adjusted to a range in which the solvent does not boil at the set heating temperature.

  Additives such as UV inhibitors and fine particles may be added batchwise to the dope, or an additive solution prepared separately may be added inline. The additive solution is obtained by dissolving an additive in an alcohol such as methanol, ethanol or butanol, a solvent such as methylene chloride, methyl acetate, acetone or dioxolane, or a mixed solvent thereof.

  In particular, part or all of the fine particles are preferably added in-line in order to reduce the load on the filter medium. When the additive solution is added in-line, it is preferable to dissolve a small amount of cellulose ester in the additive solution in order to improve mixing with the dope. The amount of the cellulose ester added to the additive solution is preferably 1 to 10 parts by mass and more preferably 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

  The in-line addition can be performed using an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer), or the like.

  The obtained dope may contain insoluble matters such as impurities contained in the cellulose ester as a raw material, for example. Such an insoluble matter can become a bright spot foreign material in the obtained film. In order to remove such insoluble matter and the like, it is preferable to filter the obtained dope.

  The dope is filtered by a filter medium such as filter paper. The absolute filtration accuracy of the filter medium is preferably small in order to highly remove insoluble matters and the like contained in the dope, but if it is too small, clogging is likely to occur. For this reason, the absolute filtration accuracy of the filter medium is preferably 0.008 mm or less, more preferably 0.001 to 0.008 mm, and still more preferably 0.003 to 0.006 mm.

  The type of the filter medium may be a normal filter medium, and may be a plastic filter medium such as polypropylene or Teflon (registered trademark), or a metal filter medium such as stainless steel. Among these, a metal filter medium is preferable from the viewpoint of less fiber dropping.

  In order to reduce the differential pressure before and after filtration, the dope is preferably filtered under heating and pressure as in the preparation of the dope. Similarly to the preparation of the dope, the heating temperature is preferably not less than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure, specifically 45 to 120 ° C. It is preferably 45 to 70 ° C, more preferably 45 to 55 ° C. The filtration pressure is preferably low, specifically 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

The dope filtration is preferably performed so that the number of bright spot foreign matters in the obtained film is not more than a certain value. Specifically, the number of bright spot foreign matters having a diameter of 0.01 mm or more is 200 / cm ² or less, preferably 100 / cm ² or less, more preferably 50 / m ² or less, and still more preferably 0. -10 pieces / cm ² or less. It is preferable that the number of bright spot foreign materials having a diameter of 0.01 mm or less is also small.

The number of bright spot foreign matter on the film can be measured by the following procedure.
i) Two polarizing plates are arranged in a crossed Nicol state, and the obtained film is arranged between them.
ii) Count the number of spots (foreign matter) where light is leaked when light is applied from one polarizing plate and observed from the other polarizing plate.

2) Step of casting dope The metal support on which the dope is cast preferably has a mirror-finished surface. Preferred examples of the metal support include a stainless steel belt and a drum whose surface is plated with a casting.

  The surface temperature of the metal support on which the dope is cast is preferably high in order to increase the drying speed of the web, but if it is too high, the web may foam or the smoothness of the web may be reduced. . Therefore, the surface temperature of the metal support is preferably set to −50 ° C. or higher and lower than the boiling point of the solvent, more preferably 0 to 40 ° C., and further preferably 5 to 30 ° C.

  The method for controlling the surface temperature of the metal support is not particularly limited, and may be a method of blowing warm air or cold air, a method of bringing hot water into contact with the back side of the metal support, or the like. From the viewpoint of efficiently transferring heat and shortening the time until the temperature of the metal support becomes constant, a method of bringing hot water into contact with the back side of the metal support is preferable.

3) About the process of drying the cast dope The cast dope is dried so that a residual solvent may become below fixed. The amount of residual solvent in the web when peeling the web from the metal support is preferably 10 to 150% by mass in order to improve the flatness of the resulting film, and 20 to 40% by mass (low residual solvent amount). Or it is more preferable that it is 60-130 mass% (high residual solvent amount), and it is further more preferable that it is 20-30 mass% (low residual solvent amount) or 70-120 mass% (high residual solvent amount).

The amount of residual solvent in the web is defined by the following formula. In the following formula, M represents the mass of a sample collected at an arbitrary point from the web being manufactured or the film after manufacture. N represents the mass of the sample after heating the sample at 115 ° C. for 1 hour.
Residual solvent amount (% by mass) = {(MN) / N} × 100

4) About the process of peeling a web Although peeling of a web is performed by a general method, it is preferable to peel with a peeling roll. Peeling with a peeling roll is preferably carried out when the web reaches the lower surface of the metal support and almost completes a round. The web peeling tension is preferably 300 N / m or less.

  The web is peeled not only by the method of peeling the web obtained after drying the dope in the step 3), but also by cooling the cast film without drying after the step 2) to remove the residual solvent. The gel may be peeled off after gelling in a state containing a large amount.

  The peeled web may be further dried. In general, the peeled web can be dried while the web is conveyed. Specifically, there are a roll drying method and a tenter method in which the peeled web is dried while being conveyed by a large number of rolls arranged vertically.

  The method for drying the web is not particularly limited, but in general, it may be a method of drying with hot air, infrared rays, heating rolls, microwaves, or the like, and from the viewpoint of simplicity, a method of drying with hot air is preferable. The drying temperature of the web is preferably increased stepwise from 40 ° C to 200 ° C.

5) About the process of extending | stretching a web The optical film which has desired retardation value Ro and Rth is obtained by extending | stretching a web. The retardation values Ro and Rth of the optical film can be controlled by adjusting the magnitude of the tension applied to the web at least in the direction (width direction) perpendicular to the web conveyance direction (the dope casting direction). it can.

  The web may be stretched at least in the width direction, and may be uniaxial stretching or biaxial stretching. The web may be stretched in the width direction or in an oblique direction with respect to the casting direction of the dope. Biaxial stretching includes stretching in both the web conveyance direction (longitudinal direction) and the width direction (lateral direction). Stretching may be sequential stretching or simultaneous stretching.

  When the web is stretched biaxially in directions orthogonal to each other, the web is finally 1.1 to 2.5 times in the width direction (lateral direction) and 0.8 in the transport direction (longitudinal direction). It is preferable to set it to -1.5 times; It is more preferable to set it to 1.2 to 2.0 times in the width direction (horizontal direction) and 0.9 to 1.0 times in the conveyance direction (vertical direction).

  The web stretching temperature is preferably 120 ° C to 200 ° C, and more preferably 140 ° C to 180 ° C. The residual solvent of the stretched web is preferably 20% by mass or less, and preferably 15% by mass or less.

  The method of stretching the web is not particularly limited, and a method in which a difference in peripheral speed is applied to a plurality of rolls and the roll is stretched in the longitudinal direction using the difference in the peripheral speed of the roll (roll stretching method). The clip and pin spacing is widened in the vertical direction and stretched in the vertical direction, widened in the horizontal direction and stretched in the horizontal direction, or stretched in both the vertical and horizontal directions and stretched in both the vertical and horizontal directions (tenter stretching, etc. Law). These stretching methods may be combined.

  In the tenter stretching method, the clip portion is preferably driven by a linear drive method. This is because the movement of the clip portion is smooth, so that it is easy to stretch and the risk of web breakage can be reduced.

  It is preferable to carry out the web width maintenance and the transverse stretching by a tenter method. The tenter method may be a pin tenter method or a clip tenter method.

  The width of the optical film obtained by stretching is preferably 4 m or less, more preferably 1 to 4 m, even more preferably 1.4 to 4 m, from the viewpoint of facilitating conveyance. It is particularly preferably 1.6 to 3 m. The optical film obtained by stretching is further dried as necessary and then wound.

3. Polarizing plate The polarizing plate of the present invention includes a polarizer and the optical film of the present invention disposed on one surface thereof, and further includes a polarizing plate protective film disposed on the other surface of the polarizer as necessary. May be included.

  A polarizer is an element that allows only light having a polarization plane in a certain direction to pass therethrough. A typical example of the polarizer is a polyvinyl alcohol-based polarizing film, and there are one in which a polyvinyl alcohol-based film is dyed with iodine and one in which a dichroic dye is dyed.

  The polarizer may be a film obtained by uniaxially stretching a polyvinyl alcohol film and then dyeing with iodine or a dichroic dye, or after dyeing a polyvinyl alcohol film with iodine or a dichroic dye, A uniaxially stretched film (preferably a film further subjected to durability treatment with a boron compound) may be used. The thickness of the polarizer is preferably 5 to 30 μm, and more preferably 10 to 20 μm.

  The polyvinyl alcohol film may be a film formed from a polyvinyl alcohol aqueous solution. The polyvinyl alcohol film is preferably an ethylene-modified polyvinyl alcohol film because it is excellent in polarizing performance and durability performance and has few color spots. Examples of the ethylene-modified polyvinyl alcohol film include an ethylene unit content of 1 to 4 mol%, a polymerization degree of 2000 to 4000, and a saponification degree of 99.0 described in JP2003-248123A and JP2003-342322A. ˜99.99 mol% film is included.

  Examples of dichroic dyes include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes.

  The optical film of the present invention may be disposed directly on one surface of the polarizer, or may be disposed via another film or layer. The optical film of the present invention is preferably an optical compensation film that also functions as a polarizing plate protective film. This is because it is not necessary to further use an optical compensation film separately from the polarizing plate protective film, and not only the liquid crystal display device can be thinned but also the manufacturing process can be simplified.

  The polarizing plate protective film other than the optical film of the present invention is not particularly limited, and may be a normal cellulose ester film or the like. Examples of commercially available cellulose ester films include commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-X KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are preferably used.

  The polarizing plate can usually be produced by laminating the polarizer and the optical film or polarizing plate protective film of the present invention. For example, the surface of the optical film of the present invention on the side in contact with the polarizer is preferably subjected to alkali saponification treatment and then bonded to the polarizer via an adhesive such as a completely saponified polyvinyl alcohol aqueous solution.

4). Liquid Crystal Display Device The liquid crystal display device of the present invention includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. And at least one is a polarizing plate which has the above-mentioned optical film among a pair of polarizing plates, Preferably both a pair of polarizing plates are polarizing plates which have the above-mentioned optical film.

  FIG. 1 is a schematic diagram showing a basic configuration of an embodiment of a liquid crystal display device according to the present invention. As shown in FIG. 1, the liquid crystal display device 10 includes a liquid crystal cell 20, a first polarizing plate 40 and a second polarizing plate 60 that sandwich the liquid crystal cell 20, and a backlight 80.

  The display method of the liquid crystal cell 20 is not particularly limited, and is a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, an IPS (In-Plane Switching) method, an OCB (Optically Compensated Birefringence Ventilating Ventilation method). There are systems (including MVA; Multi-domain Vertical Alignment and PVA; including Patterned Vertical Alignment), and HAN (Hybrid Aligned Nematic). In order to increase the contrast, the VA (MVA, PVA) method is preferable.

  A VA liquid crystal cell usually includes a pair of opposing transparent substrates and a liquid crystal layer that is sandwiched between the pair of transparent substrates and includes positive liquid crystal.

  Of at least one of the pair of transparent substrates, a pixel electrode for applying a voltage to the positive liquid crystal and a counter electrode corresponding to the pixel electrode are disposed.

  The liquid crystal layer includes positive liquid crystal molecules that are nematic liquid crystal materials having positive dielectric anisotropy. This positive type liquid crystal molecule is not applied with voltage (when no electric field is generated between the pixel electrode and the counter electrode) due to the alignment regulating force of the alignment film provided on the liquid crystal layer side surface of the transparent substrate. The major axis of the liquid crystal molecules is aligned so as to be substantially perpendicular to the surface of the transparent substrate.

  In the liquid crystal cell thus configured, an image signal (voltage) is applied to the pixel electrode, thereby generating an electric field in the horizontal direction with respect to the substrate surface between the pixel electrode and the counter electrode. Thereby, the liquid crystal molecules initially aligned perpendicularly to the surface of the transparent substrate are aligned so that the major axis thereof is in the horizontal direction with respect to the substrate surface. In this way, the liquid crystal layer is driven, and the image display is performed by changing the transmittance and reflectance of each sub-pixel.

  The 1st polarizing plate 40 is arrange | positioned at the visual recognition side, and has the 1st polarizer 42 and polarizing plate protective film 44 (F1) and 46 (F2) which clamps it. The 2nd polarizing plate 60 is arrange | positioned at the backlight 80 side, and has the 2nd polarizer 62, the polarizing plate protective film 64 (F3) and polarizing plate protective film 66 (F4) which clamps it. . One of the polarizing plate protective films 46 (F2) and 64 (F3) may be omitted as necessary.

  Of the polarizing plate protective films 44 (F1), 46 (F2), 64 (F3) and 66 (F4), at least one of the polarizing plate protective films 46 (F2) and 64 (F3) disposed on the liquid crystal cell side is used. The optical film of the present invention is preferred. The polarizing plate protective film 44 (F1) disposed on the display side may further include an antiglare layer, a clear hard coat layer, an antireflection layer, an antistatic layer, an antifouling layer, or a backcoat layer.

  Since the optical film of the present invention containing the compound represented by the general formula (1) has good retardation, the viewing angle of the liquid crystal display device can be expanded. Moreover, since the optical film of this invention containing the compound represented by General formula (1) has a favorable wavelength dispersion characteristic, it can reduce the color nonuniformity of a liquid crystal display device. Moreover, since the optical film of the present invention containing the compound represented by the general formula (1) is well compatible with the cellulose ester, the front contrast unevenness of the liquid crystal display device can be reduced. Furthermore, the optical film of the present invention containing the compound represented by the general formula (1) is not necessarily clear, but moderately hydrophobicity is imparted by the steroid group contained in the compound represented by the general formula (1). Therefore, even in an environment where the humidity varies, the variation in the viewing angle of the liquid crystal display device can be suppressed.

  In particular, even a 30-inch or larger large-screen liquid crystal display device can reduce coloring during black display due to light leakage and increase front contrast.

  In the following, the invention will be described in more detail with reference to examples. These examples do not limit the scope of the present invention.

２）一般式（１）で表される化合物
前述の化合物ＤＤＳ−１〜ＤＤＳ−１８を準備した。さらに、比較化合物として以下を準備した。

1. Preparation of materials 1) Cellulose ester The following cellulose esters A to D were prepared.

2) Compound represented by general formula (1) The above-mentioned compounds DDS-1 to DDS-18 were prepared. Furthermore, the following was prepared as a comparative compound.

2. Production of optical film (Example 1)
The following components were stirred and mixed with a dissolver for 50 minutes and then dispersed with Manton Gorin to obtain a fine particle dispersion.
[Fine particle dispersion]
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass Ethanol 89 parts by mass

While the methylene chloride was put in the dissolution tank and sufficiently stirred, the fine particle dispersion was slowly added, and then dispersed with an attritor so that the secondary particles had a predetermined particle size. The obtained solution was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.
[Fine particle additive solution]
99 parts by mass of methylene chloride 5 parts by mass of fine particle dispersion

Preparation of dope solution A dope solution having the following composition was prepared. First, methylene chloride and ethanol were charged into a pressure dissolution tank. Cellulose ester A was added to these solvents with further stirring. The obtained solution was dissolved while stirring under heating, Compound DDS-1, Monopet SB (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), a fine particle additive solution, a retardation adjusting agent (A-1), Was added and stirred until completely dissolved. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. Filtration using 244 gave a dope solution.
[Composition of dope solution]
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose ester A (cellulose diacetate having an acetyl group substitution degree of 2.42) 100 parts by mass Compound DDS-1 4 parts by mass Monopet SB (Daiichi Kogyo Seiyaku Co., Ltd.) 1 part by mass Litter Foundation adjustment agent (A-1) 4 parts by mass Particulate additive solution 1 part by mass

  Next, the dope liquid adjusted to 33 ° C. was uniformly cast on a stainless belt support of an endless belt casting apparatus so as to have a width of 1500 mm. The temperature of the stainless steel belt support was 30 ° C. After the solvent was evaporated on the stainless steel belt support until the residual solvent amount in the cast film was 75%, the paint film was applied from the stainless steel belt support at a peeling tension of 130 N / m. It peeled. The web obtained by peeling was stretched 30% (1.3 times) in the width direction using a tenter while applying heat at 145 ° C. The residual solvent amount of the web at the start of stretching was 14%. Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature in the drying zone was 130 ° C., and the film transport tension was 100 N / m. This obtained the cellulose-ester film with a film thickness of 20 micrometers.

(Examples 2 to 18)
As shown in Table 2, an optical film was obtained in the same manner as in Example 1 except that the compound represented by the general formula (1) and the addition amount thereof were changed.

(Examples 19 to 22)
As shown in Table 3, an optical film was obtained in the same manner as in Example 1 except that the type of cellulose ester, the type of compound represented by the general formula (1), and the addition amount thereof were changed.

(Example 23)
As shown in Table 3, the examples except that the kind of cellulose ester and the quantitative ratio between the cellulose ester and the compound represented by the general formula (1) were changed, and other additives were further contained. In the same manner as in Example 1, an optical film was obtained.

(Examples 24-27)
As shown in Table 3, an optical film was obtained in the same manner as in Example 1 except that the quantitative ratio between the cellulose ester and the compound represented by the general formula (1) and the film thickness were changed.

(Comparative Example 1)
As shown in Table 3, an optical film was obtained in the same manner as in Example 1 except that the compound represented by the general formula (1) was changed to a comparative compound.

(Comparative Example 2)
As shown in Table 3, an optical film was obtained in the same manner as in Example 1 except that the compound represented by the general formula (1) was not added.

  The obtained optical film was evaluated for 2-1) retardation, 2-2) wavelength dispersion, 2-3) bleed-out resistance, and 2-4) alkali saponification solution resistance by the following methods.

2-1) Retardation
i) The obtained optical film was conditioned for 2 hours in an environment of 23 ° C. and 55% RH. The average refractive index of the obtained film was measured using an Abbe refractometer (4T). Moreover, the thickness of the film was measured using a commercially available micrometer.
ii) The retardation value at the center in the width direction of the optical film was measured as follows. That is, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), light having a wavelength of 590 nm from the normal direction of the film is incident, and in the in-plane direction represented by the following formula (I) Retardation Ro was measured. Further, the retardation value R (θ) was measured when light having a wavelength of 590 nm was incident from an angle θ (incident angle (θ)) with respect to the film normal direction. θ was 30 ° to 50 °.
iii) nx, ny and nz are calculated from the measured R ₀ and R (θ) and the above-mentioned average refractive index and film thickness by an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments). Rth represented by the following formula (II) was calculated. The retardation was measured under the conditions of 23 ° C. and 55% RH.
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the film;
ny represents the refractive index in the direction y perpendicular to the direction x in the in-plane direction of the film;
nz represents the refractive index in the film thickness direction z;
d (nm) indicates the film thickness)

2-2) Wavelength dispersibility In the same manner as the retardation measurement method described above, retardation Ro (450) in the in-plane direction with light having a wavelength of 450 nm and retardation Ro (630 in the in-plane direction with light having a wavelength of 630 nm). ) And measured. The obtained Ro (450) and Ro (630) were applied to the following formula (III) to obtain a wavelength dispersive DSP. It is preferable that this value is 1.00 or less.
Formula (III) DSP = Ro (450) / Ro (630)

2-3) Bleed-out resistance The obtained optical film was allowed to stand for 1000 hours in a high-temperature and high-humidity atmosphere at 80 ° C. and 90% RH. Thereafter, the presence or absence of bleeding out (crystal precipitation) on the surface of the optical film was visually observed. The bleed-out resistance was evaluated based on the following criteria.
A: No bleed-out is observed on the surface B: Partial bleed-out is slightly observed on the surface C: Slight bleed-out is observed on the entire surface D: On the entire surface Here, a clear bleed out is recognized. Here, if the level is B level or higher, there is no practical problem, but the level A is particularly preferable.

2-4) Resistance to alkali saponification solution (coloration of saponification solution)
The optical film cut out to 5 cm × 24 cm was immersed in 40 g of an aqueous 1.5 mol / L potassium hydroxide solution at 70 ° C. for 30 hours. Then, the absorption spectrum of the potassium hydroxide aqueous solution obtained by taking out the optical film was measured using Hitachi Technologies, Ltd. spectrophotometer U-3310, and tristimulus values X, Y, and Z were calculated. From the obtained tristimulus values X, Y, and Z, yellowness YI was calculated based on JIS-K7103, and saponification liquid coloring was ranked based on the following criteria.
A: Yellowness YI is less than 1.0 B: Yellowness YI is 1.0 or more and less than 3.0 C: Yellowness YI is 3.0 or more and less than 5.0 D: Yellowness YI is 5.0 or more A ~ If it is C level, there is no practical problem, but it is preferably A or B level, particularly preferably A level.

The evaluation results of the optical films of Examples 1-27 and Comparative Examples 1-2 are shown in Tables 2 and 3.

  As shown in Tables 2 and 3, it can be seen that the optical films of Examples 1 to 23 containing the compound represented by the general formula (1) exhibit flat wavelength dispersion or reverse wavelength dispersion. Moreover, it turns out that the optical film of Examples 1-23 shows favorable retardation expression and durability (bleed-out resistance, alkali saponification liquid resistance). On the other hand, the optical film of Comparative Example 1 containing the comparative compound and the optical film of Comparative Example 2 not containing the compound represented by the general formula (1) not only exhibit forward wavelength dispersion but also durability ( It can also be seen that the bleed-out resistance and alkali saponification solution resistance are low.

  From these, it is shown that the compound represented by the general formula (1) can impart reverse wavelength dispersibility to the optical film, and is excellent in compatibility with the cellulose ester.

  Moreover, as shown from the comparison of Examples 24 to 27, it is shown that the optical films of Examples 25 and 26 having relatively thin film thicknesses have high wavelength dispersion and durability.

3. Polarizing plate (Example 28)
Production of Polarizing Plate A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched under conditions of a temperature of 110 ° C. and a stretch ratio of 5 times. The obtained film was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. . The film after immersion was washed with water and dried to obtain a polarizer having a thickness of 25 μm.

Then, according to the following steps 1 to 5, the optical film 101 is bonded to one surface of the polarizer, and the polarizing plate 101 is bonded to the other surface with Konica Minolta tack KC4UY (cellulose ester film manufactured by Konica Minolta Opto). Produced.
Step 1: Optical film 101 and Konica Minolta Tac KC4UY were each immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds. Thereafter, each film was washed with water and dried, and the surface of each film to be bonded to the polarizer was saponified.
Process 2: The above-mentioned polarizer was immersed for 1 to 2 seconds in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass.
Step 3: After lightly wiping off the excess adhesive adhering to the polarizer in Step 2, the optical film 101 saponified in Step 1 is laminated on one side of the polarizer, and in Step 1 on the other side. A saponified Konica Minoltack KC4UY was laminated.
Step 4: The optical film 101 / polarizer / Konica Minoltaack KC4UY laminate obtained in Step 3 was bonded under the conditions of a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.
Step 5: The sample bonded in Step 4 was dried at 80 ° C. for 2 minutes with a dryer to obtain a polarizing plate 101.

(Examples 29 to 50 and Comparative Examples 3 to 4)
Polarizing plates 102 to 123 and 128 to 129 were obtained in the same manner as in Example 28 except that the optical film 101 was changed as shown in Table 4.

  The wet and heat resistance of the obtained polarizing plate was evaluated by the following method.

3-1) Durability (moisture and heat resistance)
Two polarizing plate samples having a size of 500 mm × 500 mm were cut out from the obtained polarizing plate and heat-treated at 80 ° C. and 90% RH for 100 hours, respectively. Two polarizing plate samples obtained after the heat treatment were laminated so that the absorption axes were orthogonal to each other. Then, when light is irradiated from one polarizing plate sample side, the length of the white portion generated at the edge portion on the other polarizing plate sample side is measured, and the ratio to the length of one side (500 mm) of the polarizing plate sample Was calculated. The “white-out portion” to be evaluated was the longest among a plurality of white-out portions generated near the center of each of the four edge portions of the polarizing plate sample. Edge blanking occurs when two polarizing plate samples are laminated so that their absorption axes are orthogonal to each other, and the edge portion of the polarizing plate that does not transmit light passes through the light. This may cause a failure in which no image is displayed at the edge of the plate. The wet heat resistance of the polarizing plate was evaluated based on the following criteria. A and B were judged to be at a level where there was no practical problem.
A: Edge whiteness is less than 5% (a level that is not problematic as a polarizing plate)
B: White outline of edge is 5% or more and less than 10% (a level that is practically not problematic as a polarizing plate)
C: White edge of edge is 10% or more and less than 20% (a level that can be managed as a polarizing plate)
D: Edge blank is 20% or more (a problematic level as a polarizing plate)

Table 4 shows the evaluation results of Examples 28 to 50 and Comparative Examples 3 to 4.

  As shown in Table 4, it is shown that the polarizing plates of Examples 28 to 50 including the optical films 101 to 123 have higher moisture and heat resistance than the polarizing plates of Comparative Examples 3 to 4 including the optical film 128 or 129. . Although this reason is not necessarily clear, it is thought that it is because hydrophobicity is moderately given by the steroid nucleus contained in the compound represented by General formula (1) contained in the optical films 101-123.

4). Production of liquid crystal display device (Example 51)
A 40-inch display KLV-40J3000 made by SONY was prepared. Then, the polarizing plates on both sides that were previously bonded to the liquid crystal cell were peeled off, and the two polarizing plates 101 that were produced were bonded to both sides of the glass surface of the liquid crystal cell. The two polarizing plates 101 were bonded so that the optical film 101 was in contact with the liquid crystal cell, and the absorption axis of the polarizing plate 101 and the absorption axis of the polarizing plate bonded in advance were in the same direction. Thereby, the liquid crystal display device 101 was obtained.

(Examples 52-73 and Comparative Examples 5-6)
Liquid crystal display devices 102 to 123 and 128 to 129 were obtained in the same manner as in Example 51 except that the two polarizing plates 101 were changed as shown in Table 5.

  The viewing angle characteristics, the front contrast unevenness, the humidity dependence of the viewing angle, and the color unevenness of the obtained liquid crystal display device were evaluated by the following methods.

4-1) Viewing angle
i) The transmitted light amount when the liquid crystal display device is displayed in black and the transmitted light amount when the liquid crystal display device is displayed in white is the normal direction of the panel surface (the direction in which the tilt angle with respect to the normal direction of the panel surface is 0 °) To ELDIM EZ-contrast 160D. The obtained transmitted light amount was applied to the following equation to calculate the contrast.
Contrast = (transmitted light amount when displaying white) / (transmitted light amount when displaying black)
ii) Next, while the measurement position of EZ-contrast 160D manufactured by ELDIM is inclined every 10 ° from the normal direction (0 °) of the panel surface, the transmitted light amount at the time of black display at each inclination angle as described above The amount of transmitted light for white display was measured, and the contrast was calculated. And the inclination | tilt angle from which contrast becomes 10 or more was calculated | required.

The viewing angle was evaluated according to the following criteria.
A: The viewing angle is very wide (the tilt angle at which the contrast is 10 or more is 70 ° or more).
B: Wide viewing angle (tilt angle at which contrast is 10 or more is 60 ° or more and less than 70 °)
C: The viewing angle is slightly narrow (the tilt angle at which the contrast is 10 or more is 50 ° or more and less than 60 °).
D: The viewing angle is narrow (the tilt angle at which the contrast is 10 or more is less than 50 °)
Here, if it is A or B level, there is no practical problem, and it is preferable that it is A level.

4-2) Front contrast unevenness The backlight of the obtained liquid crystal display device was lit continuously for one week in an environment of 23 ° C. and 55% RH. Thereafter, using ELZIM EZ-Contrast 160D, the brightness from the normal direction of the display screen when white is displayed on the liquid crystal display device and the brightness from the normal direction of the display screen when black is displayed. Each was measured and applied to the following formula to determine the front contrast.
Front contrast = (brightness of white display measured from normal direction of display device) / (brightness of black display measured from normal direction of display device)

The front contrast at any five points on the display screen of the liquid crystal display device was measured in the same manner. Then, the average value of the five front contrasts obtained was obtained. Further, among the five front contrasts obtained, the maximum value or the minimum value of the front contrast that maximizes the difference (absolute value) from the average value was obtained. These values were applied to the following formula to determine the front contrast variation (%).
Variation in front contrast (%) = | (maximum or minimum value of front contrast) − (average value of front contrast) | / (average value of front contrast) × 100

Front contrast unevenness was evaluated according to the following criteria. A and B were judged to be at a level where there was no practical problem.
A: Variation in front contrast is 0% or more and less than 5%, and unevenness is small B: Variation in front contrast is 5% or more and less than 10%, and unevenness is somewhat C: Variation in front contrast is 10% or more Yes, the unevenness is large

4-3) Humidity dependency of viewing angle The viewing angle of the liquid crystal display device after being left in an environment of 23 ° C. and 55% RH for 5 hours is obtained by the same method as described in 4-1. -Measured using Contrast 160D. Next, the liquid crystal display device was left in an environment of 23 ° C. and 20% RH for 5 hours, and then the viewing angle was measured. Further, this liquid crystal display device was left in an environment of 23 ° C. and 80% RH for 5 hours, and then the viewing angle was measured. Finally, the liquid crystal display device was left in an environment of 23 ° C. and 55% RH for 5 hours, and then the viewing angle was measured. Then, the viewing angle measured in the first environment at 23 ° C. and 55% RH was compared with the viewing angle measured in the last environment at 23 ° C. and 55% RH, and the amount of variation in viewing angle was measured. . A and B were judged to be at a level where there was no practical problem.
A: No change in viewing angle is observed B: Some change in viewing angle is observed C: Variation in viewing angle is observed

4-4) Color unevenness From the front direction and an angle of 45 ° obliquely (an angle of 45 ° obliquely from the normal direction of the display surface) when the liquid crystal display device displays black in an environment of 23 ° C and 55% RH. The color unevenness was visually observed. Color unevenness was evaluated based on the following criteria.
A: No color unevenness B: Color unevenness is slightly observed C: Color unevenness is present but practically no problem D: Color unevenness is large and practically problematic Although it is not, it is preferable that it is A or B level, and it is especially preferable that it is A level.

  The liquid crystal display devices of Examples 51 to 73 using the polarizing plates 101 to 123 of the present invention have a wider viewing angle and the front contrast unevenness than the liquid crystal display devices of Comparative Examples 5 to 6 using the polarizing plates 128 or 129. It can be seen that the humidity dependence of the viewing angle is low and color unevenness is small. Thereby, it can be seen that a liquid crystal display device having high display performance and excellent durability can be obtained.

  The optical film of the present invention exhibits reverse wavelength dispersibility or flat wavelength dispersibility, has good compatibility with cellulose ester, and can have good durability.

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 20 Liquid crystal cell 40 1st polarizing plate 42 1st polarizer 44 Polarizing plate protective film (F1)
46 Polarizing plate protective film (F2)
60 Second polarizing plate 62 Second polarizer 64 Polarizing plate protective film (F3)
66 Polarizing plate protective film (F4)
80 Backlight

Claims (11)

An optical film containing a compound represented by the following general formula (1).

(In the formula (1),
Cyc represents a cyclic group containing a divalent 5-membered ring or 6-membered ring, and the 5-membered ring or 6-membered ring may be condensed with another ring;
R ₃ represents a substituent of the cyclic group;
j represents an integer of 0 to 4, and when j is 0, the 5-membered or 6-membered ring is condensed with another ring;
L ₁ and L ₂ are each independently a single bond, —O—, —CO—, —NRa— (Ra is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom), —S—, —SO ₂ —. And a divalent linking group selected from the group consisting of —CH ₂ —;
Str ₁ and Str ₂ each independently represents a steroid residue;
R ₁ and R ₂ each independently represent a substituent;
m and n each independently represents an integer of 0 to 10) The compound represented by the said General formula (1) WHEREIN: Cyc which has the said (R < ₃ >) j contains the structure represented by the following general formula (2) or general formula (3). Optical film.

(In the formula (2),
X ₁ and X ₂ each independently represent —S—, —O— or —NRb— (Rb represents an alkyl group having 1 to 7 carbon atoms or a hydrogen atom);
R ₄ and R ₅ each independently represents a hydrogen atom or a substituent;
- * represents a linking portion between the _{L 1} or _{L 2)}

(In formula (3),
X ₃ represents -S-, -O-, or -NRb- (Rb is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom);
R ₆ represents a hydrogen atom or a substituent;
- * represents a linking portion between the _{L 1} or _{L 2)} In the compound represented by the general formula (1), the carbon atom at the 3-position or 17-position of the steroid nucleus contained in the residue of the steroid and the L ₁ or L ₂ are directly or via a linking group. The optical film according to claim 1, wherein the optical film is bonded. In the compound represented by the general formula (1), Str ₁ having (R ₁ ) m or Str ₂ having (R ₂ ) n is derived from a cholesterol derivative or a cholic acid derivative. The optical film as described in any one of -3.   The optical film according to any one of claims 1 to 4, further comprising a cellulose ester.   The optical film of Claim 5 whose total substitution degree of the acyl group of the said cellulose ester is 2.4 or more and 3.0 or less. In an environment of 23 ° C. and 55% RH, the retardation Ro represented by the following formula (I) is 40 to 100 nm and the Rth represented by the following formula (II) is 100 to 300 nm in light having a wavelength of 590 nm. The optical film as described in any one of Claims 1-6.
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the optical film;
ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the optical film;
nz represents the refractive index in the thickness direction z of the optical film;
d (nm) represents the thickness of the optical film)   The optical film as described in any one of Claims 1-7 whose film thickness of the said optical film is 20-35 micrometers.   The polarizing plate containing a polarizer and the optical film as described in any one of Claims 1-8 arrange | positioned in the at least one surface of the said polarizer. A liquid crystal display device comprising a liquid crystal cell and a pair of polarizing plates sandwiching the liquid crystal cell,
The liquid crystal display device, wherein at least one of the pair of polarizing plates is the polarizing plate according to claim 9.   The liquid crystal display device according to claim 10, wherein the liquid crystal cell is a VA liquid crystal cell.

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