JP2012098646A - Retardation film, polarizing plate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retardation film, in which interlayer peeling is significantly improved without damaging transparency of the film.SOLUTION: The retardation film is a cellulose acylate film comprising: a core layer that contains a cellulose acylate having an acyl substitution degree Z1 satisfying 2.0<Z1<2.5; and skin layers containing a cellulose acylate having an acyl substitution degree Z2 satisfying 2.7<Z2<3.0, on both surfaces of the core layer. The cellulose acylate film shows a retardation Ro in a plane direction and a retardation Rth in a thickness direction, respectively satisfying 20≤Ro(nm)≤100 and 40≤Rth(nm)≤200. The core layer and the skin layers each contain the same additive (A) selected from a disk-like compound, a rod-like compound and a polyester compound; and the content (mass%) of the additive (A) included in one of the core layer and the skin layer is 1 mass% to 15 mass%, while the content of the additive (A) included in the other layer is 0.05 mass% to 0.50 mass%.

Description

  The present invention relates to a retardation film, a polarizing plate, and a liquid crystal display device, and more particularly to a retardation film that significantly improves delamination without impairing the transparency of the film, and a polarizing plate and a liquid crystal display device using the retardation film.

  Liquid crystal display devices are widely used in monitors for personal computers and portable devices, and for television applications because of their various advantages, such as low voltage and low power consumption, enabling miniaturization and thinning. In particular, television-use liquid crystal display devices that are expected to be viewed from various angles on a large screen have strict requirements for viewing angle dependency, and recently, the performance requirements for liquid crystal display devices for monitor use are also increasing. Therefore, various modes in which the viewing angle dependency is reduced by devising the alignment state of the liquid crystal in the liquid crystal cell have been proposed. For example, IPS (In-Plane Switching) mode, OCB (Optically Compensatory Bend) mode, VA Various studies have been made on liquid crystal display devices such as (Vertically Aligned) mode.

  However, even with these liquid crystal display devices, the viewing angle characteristics cannot be said to be sufficient, and further improvement is required. It is composed of a retardation film (also referred to as a retardation plate) and a polarizing plate for improving angular characteristics. The retardation film is used for eliminating image coloring or expanding the viewing angle, and a film provided with birefringence by stretching a resin film is attached to a polarizing plate, etc. A technique for providing birefringence as a retardation layer by providing a liquid crystal layer in which liquid crystal molecules are aligned in an arbitrary direction on a protective film for a polarizing plate is known. However, these techniques require that a retardation film and a retardation layer be provided separately from the protective film for polarizing plate, and there is a problem that the manufacturing method of the polarizing plate becomes complicated and costs increase.

  In contrast, a cellulose acylate film widely used as a protective film for polarizing plates can also be used as a retardation film to produce polarizing plates that can improve viewing angle characteristics with a simple structure. A retardation film has been proposed (see, for example, Patent Document 1).

  Cellulose acylate film has high moisture permeability and high adhesiveness with polarizers of polarizing plates in which PVA having high hydrophilicity is generally used, compared with other polymer films, and has optical isotropy. Since it is generally used as a protective film for polarizing plates used in various liquid crystal display devices, it has a simple structure without increasing the number of parts by adding a function as a retardation film to this film. It becomes possible to improve visibility.

  Patent Document 1 describes a retardation film provided with a desired retardation value by adding a retardation increasing agent to cellulose triacetate.

  However, when a retardation increasing agent is used to impart a function as a retardation film to a cellulose acylate film as in Patent Document 1, the in-plane direction retardation obtained by adding the retardation increasing agent is used. The value indicates forward wavelength dispersion (the R value is smaller as the wavelength is longer) or flat wavelength dispersion (the R value is constant regardless of the wavelength). If the in-plane retardation value has forward wavelength dispersion or flat wavelength dispersion, it is optimal for other wavelengths when it is set to a retardation value that can be optically compensated for light of a specific wavelength. Since the retardation value is not high and optical compensation over a wide band cannot be performed, improvement is demanded.

  Therefore, it has been proposed to use cellulose acetate having a low degree of acyl group substitution, such as diacetylcellulose, as a means for achieving both retardation development and wavelength dispersion (see, for example, Patent Document 2). In order to increase the retardation value, a diacetyl cellulose having a low degree of acyl group substitution is required. However, if the degree of acyl group substitution is low, the saponification resistance deteriorates. It is preferable as a constitution to form a laminated film in which the layer is diacetylcellulose and the skin layer is triacetylcellulose.

  On the other hand, in order to improve productivity in the process from polarizing plate creation to panel sticking, a method of cutting the polarizing plate after directly sticking the polarizing plate wound up with a roll to the panel is considered. Further thinning is required for cellulose acylate films as protective films for plates.

  In order to reduce the film thickness, it is necessary to perform a stretching process at a low temperature and a high stretching ratio. However, when a film is prepared by adding a high stretch ratio, the brittleness deteriorates, and in the laminated film as in Patent Document 2, when the polarizing plate is cut, “delamination” that causes tearing or separation between layers is likely to occur. I found that a problem occurred.

  When delamination occurs, it leads to a decrease in yield due to quality failure, but in particular, a slight delamination results in a significant decrease in yield when the polarizing plate taken up by the roll is directly applied to the panel and then the polarizing plate is cut. Therefore, stricter quality requirements are required than before.

  As a technique for preventing delamination, a technique of providing an adhesive layer between layers of a laminated film is disclosed (for example, refer to Patent Document 3), and Patent Document 4 discloses a glass transition temperature of an adjacent layer. A laminated retardation film is disclosed in which the difference between the two is within 5 ° C.

  Further, Non-Patent Document 1 describes that the interlayer strength depends on the compatibility (solubility parameter) of adjacent resins.

  However, the provision of the adhesive layer as in Patent Document 3 has problems in terms of cost and production load. Moreover, in patent document 4 and nonpatent literature 1, in order to match | combine a glass transition temperature and compatibility, the resin and additive which can be used for each layer are restrict | limited largely, and cellulose acylates from which an acyl group differs greatly like this subject For example, when the additive is not mixed in both, the haze increases and the transparency of the film is significantly impaired.

European Patent 0911656A2 JP 2004-268281 A JP 2003-136635 A JP 2004-163684 A

DIC Technical Review No. 14/2008 (DIC Corporation)

  It is an object of the present invention to provide a retardation film having greatly improved delamination without deteriorating the transparency of the film, and further, a polarizing plate having excellent transparency using the retardation film, and visibility. An object of the present invention is to provide a liquid crystal display device excellent in the above.

  The above object of the present invention is achieved by the following configurations.

1. Retardation having a core layer containing cellulose acylate satisfying the following formula (1) and a skin layer containing cellulose acylate satisfying the following formula (2) and having a smaller film thickness than the core layer on both surfaces of the core layer A film,
The retardation Ro in the in-plane direction and the retardation Rth in the thickness direction of the retardation film satisfy 20 ≦ Ro (nm) ≦ 100 and 40 ≦ Rth (nm) ≦ 200, respectively.
The core layer and the skin layer each contain the same additive A selected from a disk-shaped compound, a rod-shaped compound, and a polyester compound having a structure represented by the following general formula (P),
And content (mass%) of this additive A contained in any one layer of a core layer and a skin layer is 1 mass%-15 mass%, and content of this additive A contained in the other layer is A retardation film, which is 0.05% by mass to 0.50% by mass.

Formula (1) 2.0 <Z1 <2.5
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the core layer.)
Formula (2) 2.7 <Z2 <3.0
(In Formula (2), Z2 represents the total acyl substitution degree of the cellulose acylate of the skin layer.)
Formula (P) B- (GA) n-GB
(Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms) A represents an alkylenedicarboxylic acid residue having 4 to 12 carbon atoms or an aryldicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
2. The SP value (solubility parameter) of the additive A is the SP value of the cellulose acylate of the layer having a low content of the additive A than the SP value of the cellulose acylate of the layer having a high content of the additive A. 2. The retardation film as described in 1 above, which is close to.

  3. 3. The SP value (solubility parameter) of the additive A is a value between the SP value of the cellulose acylate of the core layer and the SP value of the cellulose acylate of the skin layer. Retardation film.

  4). A polarizing plate comprising the retardation film according to any one of 1 to 3 on at least one surface of a polarizer.

  5. 5. A liquid crystal display device comprising the polarizing plate according to 4 above on at least one surface of a liquid crystal cell.

  According to the present invention, it is to provide a retardation film having greatly improved delamination without impairing transparency of the film, and further, a polarizing plate excellent in transparency using the retardation film, and visibility. An excellent liquid crystal display device can be provided.

It is the schematic diagram showing the place which formed the multilayer casting web by casting with a co-casting die.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

The retardation film of the present invention includes a core layer containing a cellulose acylate satisfying the following formula (1), and a skin layer containing a cellulose acylate satisfying the following formula (2) and having a thinner film thickness than the core layer, A retardation film on both sides of the core layer,
The retardation Ro in the in-plane direction and the retardation Rth in the thickness direction of the retardation film satisfy 20 ≦ Ro (nm) ≦ 100 and 40 ≦ Rth (nm) ≦ 200, respectively.
The core layer and the skin layer each contain the same additive A selected from a disk-shaped compound, a rod-shaped compound, and a polyester compound having a structure represented by the following general formula (P),
And content (mass%) of this additive A contained in any one layer of a core layer and a skin layer is 1 mass%-15 mass%, and content of this additive A contained in the other layer is It is 0.05 mass%-0.50 mass%, It is characterized by the above-mentioned.

Formula (1) 2.0 <Z1 <2.5
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the core layer.)
Formula (2) 2.7 <Z2 <3.0
(In Formula (2), Z2 represents the total acyl substitution degree of the cellulose acylate of the skin layer.)
Formula (P) B- (GA) n-GB
(Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms) A represents an alkylenedicarboxylic acid residue having 4 to 12 carbon atoms or an aryldicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
As a result of intensive studies on the above problems, the present inventor has the same additive A used in one layer when the above-mentioned specific additive A is used in the structure of the laminated film according to claim 1. It was found that the delamination can be significantly improved by adding the additive A in the other layer only slightly to the other layer without impairing the transparency of the film.

  Further, as described in claim 2 and claim 3, when the SP value of the core / skin layer of the resin film to which the additive is added is closer to each other, adhesion between adjacent layers is increased and delamination is remarkable. It has been found that it can be improved.

  In the present specification, the “core layer” is a layer containing cellulose acylate satisfying the formula (1), and refers to a layer having the thickest thickness among the layers of the retardation film of the present invention. The “skin layer” refers to a layer containing cellulose acetate satisfying the formula (2) and having a smaller film thickness than the “core layer”. In the present invention, there is a “skin layer” on the “core layer” side of the laminated film of the “core layer” and the “skin layer”. In this case, the “skin” is disposed on both sides of the “core layer”. The “layer” may have the same or different film thickness, but it is preferable that the “layer” is thinner than the “core layer” from the viewpoint of retardation development.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail.

<Cellulose acylate>
The retardation film of the present invention includes a core layer containing a cellulose acylate satisfying the following formula (1) and a cellulose acylate satisfying the following formula (2).

Formula (1) 2.0 <Z1 <2.5
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the core layer.)
Formula (2) 2.7 <Z2 <3.0
(In Formula (2), Z2 represents the total acyl substitution degree of the cellulose acylate of the skin layer.)
First, cellulose acylate used for the core layer will be described.

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by acylating part or all of these hydroxyl groups with an acyl group. The degree of acyl substitution means the ratio of acylation of the hydroxyl groups of cellulose located at the 2-position, 3-position and 6-position (100% acylation is substitution degree 1). In addition, the substitution degree of an acyl group is calculated | required by the method prescribed | regulated to ASTM-D817-96.

  Z1 more preferably satisfies 2.1 <Z1 <2.5, and more preferably satisfies 2.15 ≦ Z1 ≦ 2.45.

  When the total acyl substitution degree of the cellulose acylate is 2.0 or less, film surface quality deterioration due to an increase in dope viscosity, haze-up due to an increase in stretching tension, and the like may occur. Further, when the total acyl substitution degree is 2.5 or more, it is difficult to obtain a necessary phase difference. Here, the dope refers to a casting solution in which cellulose acylate or an additive is dissolved in an organic solvent.

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

  The core layer according to the present invention is more preferably cellulose acetate satisfying the above formula (1), and particularly preferably diacetylcellulose.

  On the other hand, the cellulose acylate used in the skin layer according to the present invention is a cellulose acetate having a total acyl substitution degree Z2 of 2.7 <Z2 <3.0, and is preferably a cellulose triacetate. By using cellulose triacetate in which Z2 is in this range, it is possible to provide a retardation film that significantly improves delamination without impairing the transparency of the film while having excellent saponification suitability.

  The total acyl substitution degree Z2 is more preferably cellulose triacetate having an acetyl substitution degree of 2.8 ≦ Z2 ≦ 2.95.

  The degree of acetyl substitution here refers to the average value of the number of hydroxyl groups (hydroxyl groups) that are esterified (acetylated) among the three hydroxyl groups (hydroxyl groups) of each anhydroglucose that constitutes cellulose. A value in the range of 0 to 3 is shown.

  In the present invention, a portion not substituted with an acetyl group is usually present as a hydroxyl group (hydroxyl group). These can be synthesized by known methods.

  The number average molecular weight (Mn) of the cellulose acylate according to the present invention is preferably strong in the mechanical strength of a film from which a range of 30,000 to 300,000 can be obtained. Furthermore, the thing of 50000-200000 is used preferably.

  The value of the ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose acylate is preferably 1.4 to 3.0.

  The weight average molecular weight Mw and number average molecular weight Mn of the cellulose acylate were measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  Although there is no limitation in particular as a cellulose of the raw material of the cellulose acylate which concerns on this invention, Cotton linter, wood pulp, kenaf etc. can be mentioned. Moreover, the cellulose acylate obtained from them can be mixed and used at an arbitrary ratio.

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

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

  In addition, a general method for industrially synthesizing mixed fatty acid esters of cellulose is a mixed organic acid containing cellulose containing fatty acids corresponding to acetyl groups and other acyl groups (acetic acid, propionic acid, valeric acid, etc.) or acid anhydrides thereof. This is a method of acylating with components.

  Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

<Discrete compound, rod-shaped compound, and polyester compound having a structure represented by the following general formula (P)>
In the retardation film of the present invention, the core layer and the skin layer each contain the same additive A selected from a discotic compound, a rod-shaped compound, and a polyester compound having a structure represented by the following general formula (P). The content (mass%) of the additive A contained in one of the core layer and the skin layer is 1% by mass to 15% by mass, and the content of the additive A contained in the other layer is 0. It is a big feature that it is 0.05 mass%-0.50 mass%.

<Disc-like compound>
The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.

  In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.

  The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).

  The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.

  As the aromatic ring, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

  The number of carbon atoms of the aromatic ring in the retardation enhancer is preferably 2-20, more preferably 2-12, still more preferably 2-8, and 2-6. Most preferred.

  The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

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

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

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

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

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

  The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.

  The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

  The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.

  The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.

  The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (for example, an alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.

  The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.

  The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

  The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.

  The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.

  The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide.

  The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.

  The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.

  The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.

  The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.

  The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.

  Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.

  The molecular weight of the retardation developer is preferably 300 to 800.

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

In the above general formula (I):
R ²⁰¹ each independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho, meta and para positions.

X ²⁰¹ each independently represents a single bond or —NR ²⁰² —. Here, each R ²⁰² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

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

The heterocyclic group represented by R ²⁰¹ preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.

When X ²⁰¹ is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. Further, the heterocyclic group may have a hetero atom other than the nitrogen atom (for example, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below. _Here, -C _{4 H} 9 (n) indicates the _n-C 4 _{H 9.}

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

The alkenyl group represented by R ²⁰² may be a cyclic alkenyl group or a chain alkenyl group, but is preferably a chain alkenyl group, and is a straight chain alkenyl group rather than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.

The aromatic ring group and heterocyclic group represented by R ²⁰² are the same as the aromatic ring and heterocyclic ring represented by R ²⁰¹ , and the preferred range is also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of ^R201 .

  Although the specific example of a compound represented by general formula (I) below is given, it is not limited to this.

  As the discotic compound, a triphenylene compound represented by the following general formula (II) can also be preferably used.

In the general formula (II), R ^{203 to} R ²⁰⁸ each independently represent a hydrogen atom or a substituent.

Examples of the substituent represented by each of R ^{203 to} R ²⁰⁸ include an alkyl group (preferably an alkyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms. Group, ethyl group, isopropyl group, tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (preferably carbon An alkenyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, and examples thereof include a vinyl group, an allyl group, a 2-butenyl group, and a 3-pentenyl group. An alkynyl group (preferably an alkynyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably 2 to 20 carbon atoms. For example, a propargyl group, 3-pentynyl group, etc.), an aryl group (preferably an aryl group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms). A phenyl group, a p-methylphenyl group, a naphthyl group, etc.), a substituted or unsubstituted amino group (preferably having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, and particularly preferably carbon number). An amino group having 0-20, for example, an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, an anilino group, etc., an alkoxy group (preferably having 1 to 40 carbon atoms, more preferably carbon An alkoxy group having 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a methoxy group, an ethoxy group, and a butoxy group. An aryloxy group (preferably an aryloxy group having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, and particularly preferably 6 to 20 carbon atoms, such as a phenyloxy group and a 2-naphthyloxy group. Etc.), an acyl group (preferably an acyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, an acetyl group, a benzoyl group, a formyl group And a pivaloyl group), an alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a methoxycarbonyl group. , An ethoxycarbonyl group, etc.), an aryloxycarbonyl group (preferably having 7 to 40 carbon atoms, more preferably Is an aryloxycarbonyl group having 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms, such as a phenyloxycarbonyl group, and an acyloxy group (preferably having 2 to 40 carbon atoms, more preferably carbon. An acyloxy group having 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, and examples thereof include an acetoxy group and a benzoyloxy group), an acylamino group (preferably 2 to 40 carbon atoms, more preferably 2 carbon atoms). To 30 and particularly preferably an acylamino group having 2 to 20 carbon atoms, such as an acetylamino group and a benzoylamino group, and an alkoxycarbonylamino group (preferably having 2 to 40 carbon atoms, more preferably 2 carbon atoms). To 30 and particularly preferably an alkoxycarbonylamino group having 2 to 20 carbon atoms, for example, Toxylcarbonylamino group), aryloxycarbonylamino group (preferably 7 to 40 carbon atoms, more preferably 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms aryloxycarbonylamino group, Examples thereof include a phenyloxycarbonylamino group), a sulfonylamino group (preferably a sulfonylamino group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms. , A methanesulfonylamino group, a benzenesulfonylamino group and the like), a sulfamoyl group (preferably a sulfamoyl group having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, particularly preferably 0 to 20 carbon atoms, For example, sulfamoyl group, methylsulfamoyl group, dimethyls And a carbamoyl group (preferably a carbamoyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms). An unsubstituted carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, and the like, an alkylthio group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to carbon atoms). 20, for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, hexylthio group, heptylthio group, octylthio group, etc.), arylthio group (preferably having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example A phenylthio group), a sulfonyl group (preferably a sulfonyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as mesyl group, tosyl A sulfinyl group (preferably a sulfinyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a methanesulfinyl group and a benzenesulfinyl group). Ureido groups (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include unsubstituted ureido groups and methylureido groups. Groups, phenylureido groups, etc.), phosphoric acid amide groups (preferably having 1 to 40 carbon atoms, more preferably 1 to 1 carbon atoms). 0, particularly preferably a phosphoric acid amide group having 1 to 20 carbon atoms, such as a diethylphosphoric acid amide group and a phenylphosphoric acid amide group, a hydroxy group, a mercapto group, a halogen atom (for example, a fluorine atom, Chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 heterocyclic groups, for example, a heterocyclic group having a heteroatom such as nitrogen atom, oxygen atom, sulfur atom, etc., for example, imidazolyl group, pyridyl group, quinolyl group, furyl group, piperidyl group, morpholino Group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, 1,3,5-triazyl group, etc. A silyl group (preferably a silyl group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, such as a trimethylsilyl group and a triphenylsilyl group). Included). These substituents may be further substituted with these substituents. Moreover, when it has two or more substituents, they may be the same or different. If possible, they may be bonded to each other to form a ring.

The substituent represented by each of R ^{203 to} R ²⁰⁸ is preferably an alkyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an alkylthio group, or a halogen atom.

  Although the specific example of a compound represented by general formula (II) below is given, it is not limited to this.

  The compound represented by the general formula (I) is, for example, a method described in JP-A No. 2003-344655, and the compound represented by the general formula (II) is, for example, a method described in JP-A-2005-134484. Can be synthesized by a known method.

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

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

Formula (III): Ar ¹ -L ¹ -Ar ²
In the general formula (III), Ar ¹ and Ar ² are each independently an aromatic group.

  In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.

  An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocyclic ring of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable. As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxyl group, a carboxyl group, a cyano group, an amino group, an alkylamino group (for example, methyl Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (for example, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-) Dimethylcarbamoyl group), sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido Group, alkylureido group (for example, N-methylureido group, N, N-dimethylureido group, N, N, N′-tri group) Each group of tilureido group), alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, heptyl group, octyl group, isopropyl group, s-butyl group, tert-amyl group, cyclohexyl group, cyclopentyl) Group), alkenyl group (for example, vinyl group, allyl group, hexenyl group), alkynyl group (for example, ethynyl group, butynyl group), acyl group (for example, formyl group, acetyl group, butyryl group, Hexanoyl group, lauryl group), acyloxy group (for example, acetoxy group, butyryloxy group, hexanoyloxy group, lauryloxy group), alkoxy group (for example, methoxy group, ethoxy group, propoxy group, butoxy group) , Pentyloxy group, heptyloxy group, octyloxy group), aryl Xy group (for example, phenoxy group), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group ( For example, phenoxycarbonyl group), alkoxycarbonylamino group (for example, butoxycarbonylamino group, hexyloxycarbonylamino group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group) Each group), arylthio group (for example, phenylthio group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfo group) Nyl group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (for example, acetamido group, butyramide group, hexylamide group, laurylamide group) and non-aromatic heterocyclic group ( For example, a morpholyl group and a pyrazinyl group) are included.

  Among these, preferred substituents include halogen atoms, cyano groups, carboxyl groups, hydroxyl groups, amino groups, alkylamino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthio groups, and alkyl groups. Can be mentioned.

  The alkyl part and alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl group, carboxyl group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfur group. Famoyl group, ureido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, An alkylsulfonyl group, an amide group and a non-aromatic heterocyclic group are included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, a hydroxyl group, an amino group, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group, and an alkoxy group are preferable.

In the general formula (III), L ¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO— and a combination thereof.

  The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.

  The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, and most preferably 1-6. It is.

  The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.

  The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene group or ethynylene group).

  The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (III), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more.

  As the rod-like compound, a compound represented by the following formula (IV) is more preferable.

Formula ^{(IV): Ar 1 -L 2} -X-L 3 -Ar 2
In the general formula (IV), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ¹ and Ar ^{2 in} the general formula (IV).

In the general formula (IV), L ² and L ³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO— and a group consisting of a combination thereof.

  The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.

  The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene group). Or ethylene group).

L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the general formula (IV), X represents a 1,4-cyclohexylene group, a vinylene group or an ethynylene group.

  Specific examples of the compound represented by the general formula (III) or (IV) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

  Two or more rod-shaped compounds whose maximum absorption wavelength (λmax) is longer than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.

  The rod-like compound can be synthesized with reference to methods described in literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 pages (1979), 89, 93 pages (1982), 145, 111 pages (1987), 170 pages, 43 pages (1989), J. Am. Am. Chem. Soc. 113, p. 1349 (1991), p. 118, p. 5346 (1996), p. 92, p. 1582 (1970). Org. Chem. , 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

  Moreover, you may use the rod-shaped aromatic compound of pages 11-14 of Unexamined-Japanese-Patent No. 2004-50516 as said Re expression agent.

  In addition, as the retardation developer, one kind of compound can be used alone, or two or more kinds of compounds can be mixed and used. It is preferable to use two or more different compounds as the retardation enhancer because the adjustment range of retardation is widened and can be easily adjusted to a desired range.

  When the cellulose acylate film is produced by a solvent cast method, the retardation developer may be added to the dope. The addition may be performed at any timing, for example, the retardation developer may be dissolved in an organic solvent such as alcohol, methylene chloride, dioxolane, and then added to the cellulose acylate solution (dope), or You may add directly in dope composition.

  In addition, specific examples of preferable compounds of rod-like compounds other than those described in the above-mentioned publications are shown below.

  The specific examples (1) to (34), (41), and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41), and (42) have a symmetrical meso type molecular structure, there are no optical isomers (optical activity), and geometric isomers (trans Type and cis type). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

  As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type.

  Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate.

  In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

<Polyester compound represented by formula (P)>
For the cellulose ester film of the present invention, for example, a polyester compound represented by the following general formula (P) can be preferably used.

Formula (P) B- (GA) n-GB
(Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms) A represents an alkylenedicarboxylic acid residue having 4 to 12 carbon atoms or an aryldicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (P), a hydroxy group or carboxylic acid residue represented by B, an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue represented by G, an alkylene dicarboxylic acid residue represented by A or It is composed of an aryl dicarboxylic acid residue and can be obtained by the same reaction as that of a normal ester compound.

  Examples of the carboxylic acid component of the polyester compound represented by the general formula (P) include acetic acid, propionic acid, butyric acid, benzoic acid, p-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, There are ethyl benzoic acid, normal propyl benzoic acid, aminobenzoic acid, acetoxybenzoic acid, aliphatic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester compound represented by the general formula (P) include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1, 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neo Pentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3-dimethylolheptane) 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanedio 2, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. It is used as one kind or a mixture of two or more kinds.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the polyester compound represented by the general formula (P) include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. These glycols can be used as one kind or a mixture of two or more kinds.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the polyester compound represented by the general formula (P) include, for example, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. There are acids and the like, and these are used as one kind or a mixture of two or more kinds, respectively. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The polyester compound represented by the general formula (P) has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

  Although the specific compound of the polyester compound represented by general formula (P) which can be used for this invention below is shown, this invention is not limited to this.

  The retardation film of the present invention preferably contains 0.1 to 30% by mass of the polyester compound represented by the general formula (P), particularly preferably 0.5 to 10% by mass of the cellulose ester film.

(SP value)
In the retardation film of the present invention, the SP value (solubility parameter) of the additive A is lower in the content of the additive A than the SP value of the cellulose acylate in the layer having a high content of the additive A. It is preferable to be close to the SP value of the cellulose acylate of the layer in order to suppress haze and prevent delamination.

  Further, the SP value (solubility parameter) of the additive A is between the SP value of the cellulose acylate of the core layer and the SP value of the cellulose acylate of the skin layer to suppress haze and prevent delamination. This is preferable.

  The SP value, that is, the solubility parameter referred to in the present invention is a value obtained from the solubility parameter of Hildebrand, which is often used when evaluating the ease of dissolution of the non-electrolyte in an organic solvent. This solubility parameter is described in J.H. H. Hildebrand, J.M. M.M. Prausnitz. R. L. See “Regular and Related Solutions” by Scott, Van Nostrand-Reinhold, Princeton (1970), “Polymer Data Handbook Fundamentals”, Polymer Society. The solubility parameter values of various solvents are F. M.M. Barton, “Handbook of Solrity Parameters and Other Cohesion Parameters”, CRC Press, Boca Raton / Florida (1983), “Polymer Data Handbook Fundamentals”, Polymer Society.

The solubility parameter of the substance is
SP = (δE / V) ^1/2
Where δE is the cohesive energy per mole and V is the molar volume.

  The solubility parameter can be obtained by several methods, such as a method for obtaining the solubility, or a latent heat of vaporization method, a vapor pressure method, a swelling method, a surface tension method, a thermal swelling coefficient method, and a refractive index method.

(Other additives)
Other additives that can be used in the present invention are described below.

  Examples of additives other than cellulose acylate and additive A include plasticizers, ultraviolet absorbers, antioxidants, deterioration inhibitors, peeling aids, surfactants, dyes, and fine particles. In the present invention, additives other than fine particles may be added when preparing a cellulose acylate or cellulose acetate solution, or may be added when preparing a fine particle dispersion.

(Plasticizer)
The plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or an ester plasticizer. Agent, acrylic plasticizer and the like.

  Of these, when two or more plasticizers are used, at least one plasticizer is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

  The polyhydric alcohol preferably used in the present invention is represented by the following general formula (a).

Formula _{(a) R 11 - (OH} ) n
However, R ₁₁ represents an n-valent organic group, n represents a positive integer of 2 or more, and the OH group represents an alcoholic and / or phenolic hydroxyl group.

  Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these.

  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- Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like.

  In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

  Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. The inclusion of acetic acid is preferred because the compatibility with cellulose acetate increases, and it is also preferred to use a mixture of acetic acid and other monocarboxylic acids.

  Preferred 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, tridecylic acid, Saturated fatty acids such as 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, laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred 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, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.

  The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose acetate.

  The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  Below, the specific compound of a polyhydric alcohol ester is illustrated.

  The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used.

  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 glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  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, and dicyclohexyl terephthalate.

  Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

  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.

  The polyvalent carboxylic acid ester compound is composed of an ester of divalent or higher, preferably divalent to 20 valent polyvalent carboxylic acid and alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 to 20 valent.

  The polyvalent carboxylic acid is represented by the following general formula (b).

Formula (b) R ₁₂ (COOH) _m1 (OH) _n1
In the formula, R ₁₂ represents an (m1 + n1) -valent organic group, m1 represents a positive integer of 2 or more, n1 represents an integer of 0 or more, a COOH group represents a carboxyl group, and an OH group represents an alcoholic or phenolic hydroxyl group.

  Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these.

  Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

  There is no restriction | limiting in particular as alcohol used for the polyhydric carboxylic acid ester compound which can be used for this invention, Well-known alcohol and phenols can be used.

  For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.

  When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxyl group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  Preferred 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, tridecylic acid, Saturated fatty acids such as 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, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred 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 biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives can be mentioned. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

  The molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose acetate.

  The alcohol used for the polyvalent carboxylic acid ester that can be used in the present invention may be one kind or a mixture of two or more kinds.

  The acid value of the polyvalent carboxylic acid ester compound that can be used in the present invention is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value within the above range is preferable because the environmental fluctuation of retardation is also suppressed.

  In addition, an acid value means the milligram number of potassium hydroxide required in order to neutralize the acid (carboxyl group which exists in a sample) contained in 1g of samples. The acid value is measured according to JIS K0070.

  Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto.

  For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

(UV absorber)
The retardation film of the present invention may or may not contain an ultraviolet absorber. More specifically, when the OLED display device is used as a circularly polarizing plate for preventing external light reflection, an ultraviolet absorber is not essential for the retardation film, but the neck for the stereoscopic image display device is tilted. In the case of being used for preventing color change at the time, it is preferable that the display device includes an ultraviolet absorber because it is arranged on the viewing side of the polarizer.

  Examples of ultraviolet absorbers that can be used include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like. A benzotriazole-based compound with little coloring is preferable. Further, ultraviolet absorbers described in JP-A-10-182621, JP-A-8-337574, JP-A-2001-72782, JP-A-6-148430, JP-A-2002-31715, JP-A-2002-169020, 2002-2002. Polymer ultraviolet absorbers described in 47357, 2002-363420, and 2003-113317 are also preferably used. As an ultraviolet absorber, from the viewpoint of preventing the deterioration of polarizers and liquid crystals, it is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display properties, the absorption of visible light having a wavelength of 400 nm or more is small. Is preferred.

  Specific examples of UV absorbers useful in the present invention include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) ) Benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2-methylenebis ( 4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3'- ert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5 -Chloro-2H-benzotriazol-2-yl) phenyl] propionate and the like can be mentioned, but not limited thereto. As commercially available products, TINUVIN 109, TINUVIN 171, TINUVIN 326, and TINUVIN 928 (all manufactured by BASF Japan) can be preferably used. An example of the polymeric ultraviolet absorber is a reactive ultraviolet absorber RUVA-93 manufactured by Otsuka Chemical Co., Ltd.

  Specific examples of benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy- 5-benzoylphenylmethane) and the like, but is not limited thereto.

  The ultraviolet absorber described above preferably used in the present invention is preferably a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber, which has high transparency and is excellent in the effect of preventing the deterioration of the polarizing plate and the liquid crystal element, and unnecessary coloring. A benzotriazole-based ultraviolet absorber with a lower content is particularly preferably used.

  The ultraviolet absorber can be added to the dope without limitation as long as it dissolves the ultraviolet absorber in the dope. In the present invention, the ultraviolet absorber is cellulose such as methylene chloride, methyl acetate, dioxolane and the like. Dope by dissolving in a good solvent for the ester, or a mixed solvent of a good solvent and a poor solvent such as a lower aliphatic alcohol (methanol, ethanol, propanol, butanol, etc.) and adding it to the cellulose ester solution as an ultraviolet absorber solution Is preferred. In this case, it is preferable to make the dope solvent composition and the solvent composition of the ultraviolet absorber solution the same or close as possible.

(Deterioration inhibitor)
In the present invention, a known deterioration (oxidation) inhibitor such as 2,6-di-tert-butyl-4-methylphenol, 4,4'-thiobis- (6-tert-butyl-3) is added to the cellulose acylate solution. -Methylphenol), 1,1'-bis (4-hydroxyphenyl) cyclohexane, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, pentaerythris A phenolic or hydroquinone antioxidant such as lithyl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] can be added. Further, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert) It is preferable to use a phosphorus-based antioxidant such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The addition amount of the deterioration inhibitor is 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the cellulose resin.

(Peeling accelerator)
The retardation film of the present invention preferably contains a release accelerator from the viewpoint of improving releasability. The peeling accelerator can be included at a ratio of 0.001 to 1% by mass, for example, and the addition of 0.5% by mass or less is preferable because separation of the release agent from the film hardly occurs. 005% by mass or more is preferable because a desired peeling reduction effect can be obtained. Therefore, it is preferably included at a rate of 0.005 to 0.5% by mass, and at a rate of 0.01 to 0.3% by mass. More preferably. As the peeling accelerator, known ones can be adopted, and organic and inorganic acidic compounds, surfactants, chelating agents and the like can be used. Among them, polyvalent carboxylic acids and esters thereof are effective, and in particular, ethyl esters of citric acid can be used effectively.

  The retardation film of the present invention preferably contains a peeling accelerator in the skin layer.

(Matting agent)
In particular, the retardation film of the present invention is generally added with fine particles in order to prevent the film from being scratched or being deteriorated in handling. They are called matting agents, anti-blocking agents or anti-scratching agents and have been used conventionally. They are not particularly limited as long as they have the above-described functions, and may be an inorganic compound matting agent or an organic compound matting agent.

  Specific examples of the inorganic compound matting agent include silicon-containing inorganic compounds (for example, silicon dioxide, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, etc.), titanium oxide, and zinc oxide. , Aluminum oxide, barium oxide, zirconium oxide, strongtium oxide, antimony oxide, tin oxide, tin oxide / antimony, calcium carbonate, talc, clay, calcined kaolin, calcium phosphate, etc., more preferably silicon-containing inorganic compounds and oxides Although it is zirconium, since the turbidity of a cellulose acylate film can be reduced, silicon dioxide is particularly preferably used. As the silicon dioxide fine particles, for example, commercially available products having trade names such as Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used. As the zirconium oxide fine particles, for example, those commercially available under trade names such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.

  Preferable specific examples of the organic compound matting agent include, for example, polymers such as silicone resin, fluorine resin and acrylic resin, and among them, silicone resin is preferably used. Among the silicone resins, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, Tospearl 105, Tospearl 108, Tospearl 120, Tospearl 145, Tospearl 3120 and Tospearl 240 (manufactured by Toshiba Silicone Co., Ltd.) A commercial product having a trade name can be used.

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

  The retardation film of the present invention contains a matting agent in the skin layer, is resistant to scratches by reducing the coefficient of friction on the film surface, prevents creaking that occurs when a wide film is wound long, and prevents film breakage From the viewpoint of

  In the retardation film of the present invention, if the matting agent is not added in a large amount, the haze of the film does not increase, and when actually used in an LCD, inconveniences such as a decrease in contrast and generation of bright spots are unlikely to occur. If the amount is too small, the above-mentioned creaking and scratch resistance can be realized. From these viewpoints, it is preferably included at a ratio of 0.01 to 5.0 mass%, more preferably included at a ratio of 0.03 to 3.0 mass%, and a ratio of 0.05 to 1.0 mass% It is particularly preferable to include

<Manufacture of retardation film>
The retardation film of the present invention is a retardation film having a core layer and a skin layer thinner than the core layer on both surfaces of the core layer, and a cellulose acylate solution (dope prepared in the core layer and the skin layer). ), A laminated retardation film having a multilayer structure can be produced by a solvent cast method.

  In the production of the retardation film of the present invention, a step of preparing a dope by dissolving cellulose acylate, additive A, and other additives in a solvent, and casting the dope on a belt-like or drum-like metal support. By the process, the process of drying the cast dope as a web, the process of peeling from the metal support, the process of stretching, the process of further drying, the process of further heat treating the obtained film if necessary, the process of winding after cooling Done. The retardation film of the present invention preferably contains 60 to 95% by mass of cellulose acylate in the solid content.

(Dope preparation)
The process for preparing the dope will be described. The concentration of cellulose acylate in the dope is preferably higher because the drying load after casting on the metal support can be reduced, but if the concentration of cellulose acylate is too high, the load during filtration increases. Filtration accuracy deteriorates. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used in the dope may be used alone or in combination of two or more, but it is preferable in terms of production efficiency that a good solvent and a poor solvent of cellulose acylate are mixed, and the good solvent is used. A larger amount is preferable from the viewpoint of the solubility of cellulose acylate. The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose acylate to be used independently is defined as a good solvent, and a solvent that swells or does not dissolve alone is defined as a poor solvent. Therefore, depending on the acetyl group substitution degree of cellulose acylate, the good solvent and the poor solvent change. For example, when acetone is used as a solvent, cellulose acetate (acetyl substitution degree 2.4) becomes a good solvent, and cellulose acetate Esters (acetyl group substitution degree 2.8) are poor solvents.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope.

  As a method for dissolving cellulose acylate when preparing the dope described above, a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos. In addition, a method in which cellulose acylate is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.

  The pressurization may 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.

  A higher heating temperature with the addition of a solvent is preferable from the viewpoint of the solubility of cellulose acylate, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  Alternatively, a cooling dissolution method is also preferably used, whereby cellulose acylate can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose acylate solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like. However, if the absolute filtration accuracy is too small, there is a problem that the filter medium is likely to be clogged. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose acylate by filtration.

The bright spot foreign material is arranged in a crossed Nicols state with two polarizing plates, a cellulose acylate film is placed between them, light is applied from the side of one polarizing plate, and observation is performed from the side of the other polarizing plate. It is a point (foreign matter) where light from the opposite side sometimes leaks, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less. More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / m < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable. A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

(Casting)
Here, the dope casting will be described.

  From the cellulose acylate solution (dope) prepared for the core layer and skin layer according to the present invention, a cellulose acylate film having a multilayer structure can be produced by a solvent cast method.

(Co-casting)
In the present invention, the obtained cellulose acylate solution (dope) is preferably formed by casting the two or more kinds of cellulose acylate solutions on a smooth band or drum as a support.

  Two or more kinds of dopes may be cast on the support at the same time or separately on the support. In the case of the sequential casting method in which the casting is performed separately, the dope on the support side can be cast first and dried to some extent on the support, and then overlaid on the support. When three or more kinds of dopes are used, a film having a laminated structure can be produced by appropriately combining simultaneous casting (also called co-casting) and sequential casting. These methods, which are formed by co-casting or sequential casting, differ from the method of coating on a dried film, and the boundary of each layer of the laminated structure becomes unclear, and the laminated structure is clear by observing the cross section. There is a feature that there is a case where there is no separation, there is an effect of improving the adhesion between each layer.

  The production method of the retardation film of the present invention is preferably carried out by co-casting from the viewpoint of productivity, and a known co-casting method can be used. For example, the film may be produced while casting and laminating a solution containing cellulose acylate from a plurality of casting ports provided at intervals in the traveling direction of the metal support. The methods described in JP-A Nos. 158414, 1-122419, and 11-198285 can be applied. Further, it may be formed into a film by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, It can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Further, a cellulose acylate film in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded. A casting method may be used. Furthermore, it is also a preferred embodiment that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution.

  Alternatively, by using two casting ports, the film cast on the metal support is peeled off by the first casting port, and the second casting is performed on the side in contact with the metal support surface. Further, a film may be prepared, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Furthermore, the cellulose acylate solution according to the present invention can be simultaneously cast with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer). . As a method for producing the film of the present invention, it is preferable that the film formation is simultaneous or sequential multilayer casting.

  In the case of co-casting, the thickness of each layer is not particularly limited as long as the skin layer is thinner than the core layer, but preferably the skin layer is 0.2 to 50% of the total thickness of the retardation film. It is preferable that the thickness is 2 to 30%. In the case of co-casting of three or more layers and when there are a plurality of skin layers made of cellulose acylate satisfying the formula (2), the total thickness of the skin layers is 0.2 of the total thickness of the retardation film. It is preferably ˜50%, more preferably 2 to 30%.

  Moreover, it is also a preferable aspect that a release agent is included only in the layer on the metal support side. In order to cool the metal support by the cooling drum method to gel the solution, it is also preferable to add more alcohol as a poor solvent to the layer in contact with the support than the other layer. The viscosity of the solution containing cellulose acylate at the time of casting may be different between the core layer and the skin layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller.

  In the method for producing a film of the present invention, as described above, the additive A selected from the disk-shaped compound, the rod-shaped compound, or the polyester compound having the structure represented by the general formula (P) is added to both the core layer and the skin layer. The additive A of the same type is contained in one of the core layer and the skin layer, and the content (mass%) of the additive A contained in one of the core layer and the skin layer is 1% by mass to 15% by mass. Cellulose acylate with a layer content of 0.05% to 0.50% by weight, which improves the expression of retardation and significantly improves delamination without impairing the transparency of the film. A film having a multilayer structure can be obtained.

  In the present invention, the multi-layer cast dope is dried and peeled from the support.

  The dope is cast on a drum or metal support and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35% by mass. The surface of the drum or metal support is preferably finished in a mirror state. For casting and drying methods in the solvent casting method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,739,69, British Patent 6,407,331, No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-1115035.

  The dope is preferably cast on a drum or metal support having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from a drum or a metal support, and further dried by high-temperature air whose temperature is successively changed from 100 ° C. to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or metal support during casting.

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is set to −50 ° C. to a temperature at which the solvent boils and does not foam. A higher temperature is preferable because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate. The preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  In order for the retardation film of the present invention to exhibit good planarity, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 60%. It is 130 mass%, Most preferably, it is 20-30 mass% or 70-120 mass%. The temperature at the peeling position on the metal support is preferably −50 to 40 ° C., more preferably 10 to 40 ° C., and most preferably 15 to 30 ° C.

  In the present invention, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Note that M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  In the retardation film drying step, the web is peeled off from the metal support, further dried, and dried until the residual solvent amount is 0.5% by mass or less.

  In the film drying process, generally, a roll drying method (a method in which a plurality of rolls arranged on the upper and lower sides are alternately passed through and dried) or a method of drying while transporting the web by a tenter method is adopted.

  When peeling from the metal support, the web is stretched in the longitudinal direction due to the peeling tension and the subsequent conveying tension. Therefore, in the present invention, when peeling the web from the casting support, the peeling and conveying tensions are reduced as much as possible. It is preferable to carry out in the state. Specifically, for example, it is effective to set it to 50 to 170 N / m or less. At that time, it is preferable to apply a cold air of 20 ° C. or less to fix the web rapidly.

(Stretching process)
The retardation film of the present invention preferably stretches the web at least 1.1 times in the TD direction (width direction). The range of stretching is preferably 1.1 to 2.0 times, and more preferably 1.2 to 2.0 times. If it is less than 1.1 times, the movement of molecules in the film is small, and not only the desired retardation value cannot be obtained, but also it is difficult to make the density difference (void) in the film uniform.

  Furthermore, after the film is formed, when the residual solvent amount is 40% by mass or more, the film starts to be stretched in the MD direction (casting direction, longitudinal direction), and the residual solvent amount is less than 40% by mass. Sometimes, it is preferable to stretch in the TD direction (width direction).

  The draw ratio in the MD direction of the cellulose ester film is preferably 1.05 to 1.3 times, and more preferably 1.05 to 1.15 times.

  In order to stretch in the MD direction, it is preferable to peel at a peeling tension of 130 N / m or more, and particularly preferably 150 to 170 N / m. Since the web after peeling is in a high residual solvent state, stretching in the MD direction can be performed by maintaining the same tension as the peeling tension. As the web dries and the residual solvent amount decreases, the draw ratio in the MD direction decreases.

  The draw ratio in the MD direction can be calculated from the rotation speed of the belt support and the tenter operation speed.

  In order to stretch in the TD direction, for example, the entire drying process as shown in JP-A-62-46625 or a part of the process is dried while holding the width at both ends of the web with clips or pins in the width direction. Among them, a tenter method using a clip and a pin tenter method using a pin are preferably used.

  The drying temperature in the case of performing the tenter is preferably 100 to 250 ° C, more preferably 130 to 240 ° C, and most preferably 160 to 220 ° C in the case of stretching at a high magnification as in the present invention. The lower the drying temperature, the less the transpiration of UV absorbers, plasticizers, etc., the better the process contamination, and the higher the drying temperature, the better the film flatness and elastic modulus.

  Although the retardation film of the present invention necessarily has retardation by stretching, the in-plane retardation value Ro is 590 nm using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments). It can be calculated from the obtained refractive indexes nx, ny and nz by measuring the three-dimensional refractive index at the wavelength.

  The retardation film Ro of the present invention has an in-plane retardation value Ro of 20 to 100 nm, and a polarizing plate having excellent viewing angle characteristics when the thickness direction retardation value Rth is in the range of 40 to 200 nm. Is preferable.

Ro = (nx−ny) × d
Rth = ((nx + ny) / 2−nz) × d
(In the formula, nx, ny, and nz represent the refractive indexes in the principal axis x, y, and z directions of the refractive index ellipsoid, respectively, and nx and ny represent the refractive index in the film in-plane direction, and nz represents the thickness direction of the film. (In addition, nx> ny, and d represents the thickness (nm) of the film.)
(Drying process)
The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the web drying step is preferably a glass transition point of the film of −5 ° C. or less, and it is effective to perform a heat treatment at 100 ° C. or more and 10 minutes or more and 60 minutes or less. Drying is performed at a drying temperature of 100 to 200 ° C, more preferably 110 to 160 ° C.

  After the predetermined heat treatment, it is preferable to provide a slitter and cut off the end portion before winding to obtain a good winding shape. Furthermore, it is preferable to knurling both ends of the width.

(Knurling)
The knurling process can be formed by pressing a heated embossing roll. Fine embossing is formed on the embossing roll, and the embossing roll can be pressed to form asperity on the film and make the end bulky.

  The height of the knurling at both ends of the width of the retardation film of the present invention is preferably 4 to 20 μm and a width of 5 to 20 mm.

  In the present invention, the knurling process is preferably provided after the drying in the film forming process and before winding.

(Winding process)
This is a step of winding up as a retardation film after the amount of residual solvent in the web becomes 2% by mass or less, and by making the residual solvent amount 0.4% by mass or less, a film having good dimensional stability can be obtained. it can.

  As a winding method, a generally used method may be used. There are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

  To adjust the film thickness, it is necessary to control the dope concentration, the pumping amount of the pump, the slit gap of the die base, the extrusion pressure of the die, the speed of the casting support, etc. so as to obtain the desired thickness. Good.

  Further, as a means for making the film thickness uniform, it is preferable to use a film thickness detection means to feed back and adjust the programmed feedback information to each of the above devices.

  So far, the method for producing a retardation film by laminating cellulose acylate by co-casting has been described. However, the retardation film according to the present invention is formed in advance from cellulose acylate satisfying the formula (1). A film made of cellulose acylate satisfying the formula (2) and a film bonded with an adhesive may be stretched, and after saponifying each of these films by a known method, polyvinyl alcohol It may be produced by stretching a laminated film bonded with a water-soluble polymer adhesive.

(Haze)
The retardation film of the present invention preferably has a haze of less than 1%, more preferably less than 0.5%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as an optical film.

(Average moisture content)
In the retardation film of the present invention, the equilibrium water content at 25 ° C. and 60% relative humidity is preferably 4% or less, more preferably 3% or less. By setting the average moisture content to 4% or less, it is easy to cope with changes in humidity, and the optical characteristics and dimensions are more difficult to change.

(Film thickness)
The total thickness of the retardation film according to the present invention is preferably 80 μm or less, and more preferably 50 μm or less. A film thicker than 80 μm is not preferable because it tends to cause a change in color and the like, and is not preferable because it does not match the trend of thinning display devices in recent years.

(Film length, width)
The retardation film of the present invention is preferably long, specifically, preferably has a length of about 100 to 10000 m, and is wound into a roll. In addition, the width of the retardation film of the present invention is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably 1.4 to 4 m.

<Polarizing plate>
The retardation film of this invention can be used for a polarizing plate and a liquid crystal display device using the same.

  The polarizing plate is characterized in that it is a polarizing plate in which the retardation film of the present invention is bonded to at least one surface of a polarizer. The liquid crystal display device of the present invention is characterized in that the polarizing plate according to the present invention is bonded to at least one liquid crystal cell surface via an adhesive layer.

  The polarizing plate can be produced by a general method. The retardation side of the retardation film of the present invention is preferably bonded to at least one surface of a polarizer prepared by subjecting the polarizer side to alkali saponification treatment and immersion drawing in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution.

  Even if it uses this retardation film for another surface, it is also preferable to paste another film. For example, commercially available cellulose ester films (for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC8UX-RWA, KC8UX-RHA, KC8UX-RHA, KC8UX KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) is preferably used.

  In addition to the antiglare layer or the clear hard coat layer, the viewing side protective film of the polarizing plate used on the surface side of the display device preferably has an antireflection layer, an antistatic layer, an antifouling layer, and a backcoat layer.

  A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed.

  For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound. The film thickness of the polarizer is preferably 5 to 30 μm, particularly preferably 10 to 20 μm.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol%. Ethylene-modified polyvinyl alcohol is also preferably used.

  Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used.

  A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has few color spots, and is particularly preferably used for a large-sized liquid crystal display device.

  The polarizer obtained as described above is usually used as a polarizing plate with a protective film bonded to both sides or one side. Examples of the adhesive used for pasting include a PVA-based adhesive and a urethane-based adhesive. Among them, a PVA-based adhesive is preferably used.

<Liquid crystal display device>
By using the polarizing plate on which the retardation film of the present invention is bonded to a liquid crystal display device, the liquid crystal display device of the present invention excellent in various visibility can be produced.

  The retardation film of the present invention can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB. A VA (MVA, PVA) type liquid crystal display device is preferable.

  In particular, even a large-screen liquid crystal display device having a screen size of 30 or more can provide a liquid crystal display device with excellent visibility such as uneven coloring and front contrast.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
<Preparation of cellulose acylate>
To 100 parts by mass of cellulose, 16 parts by mass of sulfuric acid, 260 parts by mass of acetic anhydride and 420 parts by mass of acetic acid were added, and the temperature was raised from room temperature to 60 ° C. over 60 minutes while stirring, and the temperature was maintained for 15 minutes. An acetylation reaction was performed. Next, a mixed solution of magnesium acetate in acetic acid-water was added to neutralize the sulfuric acid, steam was introduced into the reaction system, and the mixture was maintained at 60 ° C. for 120 minutes for saponification aging treatment. Thereafter, washing was performed with a large amount of water until the odor of acetic acid disappeared, and after further drying, cellulose acylate having an acetyl group substitution degree of 2.20 was obtained.

  Subsequently, cellulose acylates having the degree of acetyl substitution shown in Table 2 were prepared in the same manner except that the amount of acid was adjusted.

<Compound used in Example 1>
As the additive A according to the present invention, compounds shown in Table 1 below were used.

Compound _{C: OH-CH (C 4} H 9) -CH 2 -OCO- (CH 2) 4 -OCO-CH (C 4 H 9) -CH 2 -OH
Compound _{F: OH-CH (CH 3} ) -CH 2 -OCO- (CH 2) 4 -OCO-CH (CH 3) -CH 2 -OH
The SP value of each additive was measured by the above measuring method.

<Preparation of retardation film 101>
<Fine particle dispersion 1>
Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate having an acetyl substitution degree of 2.30 was added to a pressure dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of main dope solution>
The following two types of dopes were prepared, and a laminated retardation film 101 having a structure of skin layer / core layer / skin layer was prepared by co-casting.

(Preparation of cellulose acylate dope for core layer)
Cellulose acetate (acetyl substitution degree 2.20) 100 parts by weight Compound A 10 parts by weight Dichloromethane 406 parts by weight Methanol 61 parts by weight (Preparation of cellulose acylate dope for skin layer)
Cellulose acetate (acetyl substitution degree 2.90) 100 parts by weight Compound A 0.25 part by weight Fine particle additive solution 1 2 parts by weight Dichloromethane 406 parts by weight Methanol 61 parts by weight Each of the above compositions is put into a mixing tank and stirred. After dissolving each component, each cellulose acylate dope was prepared by filtering through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm. The dope was co-cast with a band casting machine so as to have a three-layer structure of skin layer / core layer / skin layer. Here, the core layer is made the thickest by adjusting the casting amount of each dope so that the film thickness after stretching is 15 μm for the core layer and 10 μm for the skin layer, for a total of 45 μm. Simultaneous multi-layer casting was performed. A film peeled off from the band with a residual solvent amount of about 30% by mass was applied with hot air at 160 ° C. with a tenter and widened to a draw ratio of 32%, and then relaxed at 140 ° C. for 60 seconds so that the draw ratio was 30%. I let you. Thereafter, the tenter transport was shifted to the roll transport, and further dried at 120 to 150 ° C. and wound up.

<Preparation of retardation films 102 to 149>
In the production of the retardation film 101, retardation films 102 to 149 were produced in the same manner except that the type of cellulose acylate, the type of compound, and the addition amount were changed as shown in Tables 2 and 3.

<Evaluation>
<Retardation>
Three-dimensional refractive index measurement at a wavelength of 590 nm was performed with an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) using the prepared retardation film, and the obtained refractive indexes nx, ny, nz From this, it was calculated by substituting into the following formula.

Ro = (nx−ny) × d
Rth = ((nx + ny) / 2−nz) × d
(In the formula, nx, ny, and nz represent the refractive indexes in the principal axis x, y, and z directions of the refractive index ellipsoid, respectively, and nx and ny represent the refractive index in the film in-plane direction, and nz represents the thickness direction of the film. (In addition, nx> ny, and d represents the thickness (nm) of the film.)
<Delamination>
The polarizing plate was cut into a square of 20 cm × 20 cm in an atmosphere of 23 ° C. and 55% RH, and the cross section was observed with a microscope. This operation was performed with 10 polarizing plates per one level sample, and evaluated according to the following criteria.

A: There is no sample where peeling is observed between layers. ○: 1-2 samples where peeling is observed between layers. Δ: 3-5 samples where peeling is observed between layers. X: 6 samples where peeling is observed between layers. Or more <Haze>
About the produced retardation film, the haze value was measured. The measurement was performed on one film sample using NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS-K7136 and evaluated according to the following criteria.

◎: Haze is less than 0.5% ○: Haze is less than 1.0% △: Haze is less than 1.5% ×: Haze is 1.5% or more

  From the above table, it can be seen that the retardation film of the present invention is an excellent retardation film because it has a desirable retardation as a retardation film, is excellent in delamination and has a low haze.

Example 2
<Preparation of polarizing plates 101-149>
A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times).

  This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, 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. This was washed with water and dried to obtain a polarizer.

  Next, the polarizer and the retardation films 101 to 149 prepared in Example 1 according to the following steps 1 to 5 are bonded together with Konica Minolta Tack KC4UY (Konica Minolta Opto Cellulose Ester Film) on the back side for polarization. Plates 101-149 were produced.

  Step 1: The film is immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water, dried, and saponified on the side to be bonded to the polarizer, the retardation films 101 to 149 and Konica Minoltac KC4UY. Obtained.

  Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was gently wiped off, and this was placed on the retardation films 101 to 149 processed in Step 1.

Step 4: The retardation films 101 to 149, the polarizer, and the back side Konica Minol Tack KC4UY laminated in Step 3 were bonded at a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.

  Step 5: Samples obtained by bonding the polarizer prepared in Step 4 with the retardation film 101-149 and Konica Minolta Tack KC4UY in a dryer at 80 ° C. for 2 minutes are dried on the retardation films 101-149, respectively. Corresponding polarizing plates 101 to 149 were prepared.

<Production of liquid crystal display device>
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated.

  The polarizing plates on both sides of the 40-inch display BRAVIA X1 made in advance were peeled off, and the produced polarizing plates 101 to 149 were bonded to both surfaces of the glass surface of the liquid crystal cell.

  At that time, the direction of bonding of the polarizing plate is such that the surfaces of the retardation films 101 to 149 are on the liquid crystal cell side, and the absorption axis is in the same direction as the previously bonded polarizing plate. Thus, liquid crystal display devices 101 to 149 corresponding to the polarizing plates 101 to 149 were produced, respectively.

<Evaluation>
(Evaluation of viewing angle)
About each produced said liquid crystal display device, the average value of contrast ratio (white transmittance | permeability / black transmittance | permeability) was calculated | required in the up-down and left-right direction in the polar angle of 60 degrees using the measuring machine (EZ-Contrast160D, ELDIM company make). .

A: 40-50
○: Less than 30 to 40 Δ: Less than 20 to 30 ×: Less than 10 to 20 (Front contrast of liquid crystal display device)
The front contrast of each liquid crystal display device was measured. The front contrast was measured by a front contrast measuring device (EZ-contrast) manufactured by ELDIM, and the light quantity during white display and black display was measured. The measurement results were ranked according to superiority or inferiority according to the value of the front contrast as follows.

A: Front contrast ratio = 3000: 1 or more B: Front contrast ratio = 2999: 1 to 2000: 1
Δ: Front contrast ratio = 1999: 1 to 1000: 1
X: Front contrast ratio = 999: 1 or less

  It can be seen from Table 4 that the retardation film of the present invention, the polarizing plate using the same, and the liquid crystal display device are superior in viewing angle and front contrast as compared with the comparative example.

DESCRIPTION OF SYMBOLS 10 Co-casting die 11 Base part 13, 15 Slit for skin layer 14 Slit for core layer 16 Metal support 17, 19 Dope for skin layer 18 Dope for core layer 20 Multilayer structure web 21 Skin layer 22 Core layer 23 Skin layer

Claims (5)

Retardation having a core layer containing cellulose acylate satisfying the following formula (1) and a skin layer containing cellulose acylate satisfying the following formula (2) and having a smaller film thickness than the core layer on both surfaces of the core layer A film,
The retardation Ro in the in-plane direction and the retardation Rth in the thickness direction of the retardation film satisfy 20 ≦ Ro (nm) ≦ 100 and 40 ≦ Rth (nm) ≦ 200, respectively.
The core layer and the skin layer each contain the same additive A selected from a disk-shaped compound, a rod-shaped compound, and a polyester compound having a structure represented by the following general formula (P),
And content (mass%) of this additive A contained in any one layer of a core layer and a skin layer is 1 mass%-15 mass%, and content of this additive A contained in the other layer is A retardation film, which is 0.05% by mass to 0.50% by mass.
Formula (1) 2.0 <Z1 <2.5
(In formula (1), Z1 represents the total acyl substitution degree of the cellulose acylate of the core layer.)
Formula (2) 2.7 <Z2 <3.0
(In Formula (2), Z2 represents the total acyl substitution degree of the cellulose acylate of the skin layer.)
Formula (P) B- (GA) n-GB
(Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms) A represents an alkylenedicarboxylic acid residue having 4 to 12 carbon atoms or an aryldicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)   The SP value (solubility parameter) of the additive A is the SP value of the cellulose acylate of the layer having a low content of the additive A than the SP value of the cellulose acylate of the layer having a high content of the additive A. The retardation film according to claim 1, wherein the retardation film is close to.   The SP value (solubility parameter) of the additive A is a value between the SP value of the cellulose acylate of the core layer and the SP value of the cellulose acylate of the skin layer. Retardation film.   A polarizing plate comprising the retardation film according to claim 1 on at least one surface of a polarizer.   A liquid crystal display device comprising the polarizing plate according to claim 4 on at least one surface of a liquid crystal cell.

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