JP2013222006A - Optical film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film which is excellent in adhesion, liquid crystal alignment, and planar shape of a retardation layer between a substrate, an interlayer (acrylic layer) and the retardation layer, in which the oriented state of liquid crystal material is immobilized, and which can be also thinned, and provide a retardation film, a polarizing plate, and a liquid crystal display device using such an optical film.SOLUTION: In an optical film, on a substrate of cellulose acylate, an acrylic layer is provided which contains an acrylic compound in which at least one hydroxy group of a polyhydric alcohol compound is substituted by a (meth)acryloyl group, and a polymerizable compound having a polar group and a polymerizable group, and on the acrylic layer, a retardation layer is provided in which the oriented state of liquid crystal material is immobilized.

Description

  The present invention relates to a retardation film suitable for optical compensation of liquid crystal display devices of various alignment modes, an optical film having a retardation layer formed by fixing the alignment state of a liquid crystalline compound used in a polarizing plate, and the like, and its production Regarding the method.

In a liquid crystal display device, optical compensation is performed to improve image quality such as wide viewing angle, contrast improvement, and color shift suppression. Optical compensation means the function of correcting the birefringence that occurs when light passes through the birefringent members that make up the liquid crystal display device when the liquid crystal display device displays an image. This is done by disposing a retardation layer (optically anisotropic layer) that eliminates the property.
This retardation layer can be obtained by developing the birefringence of a material having birefringence. For example, a method of obtaining a retardation layer as a film by forming a material exhibiting birefringence such as cyclic polyolefin or cellulose, or a method of obtaining a retardation layer by aligning a liquid crystalline compound having birefringence is known. It has been. The latter retardation layer has higher retardation than the former retardation layer and often takes the form of a retardation film formed on a support such as a film.
As such a retardation film, a laminate in which an alignment film (intermediate layer) containing a polyvinyl alcohol-based resin and a layer in which rod-like liquid crystalline compounds are vertically aligned are provided on a cellulose acylate film (support). A type of retardation film is known.
For example, Patent Document 1 describes a retardation film having an intermediate layer containing a cellulose ester between an optically biaxial transparent film and an optically anisotropic layer. It is described that it can contain an acrylic polymer that can have a polar group such as.
However, further formation of a saponified and washed alignment film is required, production is still complicated, and the retardation film cannot be thinned, and there is a problem in adhesion between each layer. .
Patent Document 2 describes a vertical alignment film composed of a cross-linked block copolymer composed of alkyl (meth) acrylate monomer units.
However, there is a problem in uniformity in the film from the viewpoint of occurrence of microphase separation due to the block copolymer, a problem in thinning the retardation film from the viewpoint of the curing strength of the vertical alignment film, and the vertical alignment. There was also a problem with the surface shape of the liquid crystal alignment layer formed on the film.

JP 2009-122422 A JP 2005-148473 A

  In view of the problems of the conventional technology, the object of the present invention is excellent in the adhesion of the support, the intermediate layer (acrylic layer) and the retardation layer in which the alignment state of the liquid crystal material is fixed, the liquid crystal alignment, and the retardation layer surface. An object of the present invention is to provide an optical film that can be thinned more easily than conventionally known methods.

As a method for producing retardation films of various orientations, the present inventors initially studied a conventional production method in which a cellulose film support is saponified, washed, coated with a polyvinyl alcohol (PVA) orientation film, and a retardation layer is applied. As a result, the steps of saponification, washing with water, and application of PVA were complicated, and as a result, the retardation film could not be thinned and the yield was thought to be poor.
On the other hand, the present inventors have achieved a reduction in the thickness of the retardation film by providing a hydrophilic acrylic layer as an intermediate layer without requiring complicated steps such as saponification, washing with water, and application of PVA, and yield is also improved. I found a good thing.
The present invention has been completed based on the above findings.
The above-mentioned subject is achieved by the following means.

[1]
An acrylic layer containing an acrylic compound in which at least one hydroxyl group of a polyhydric alcohol compound is substituted with a (meth) acryloyl group and a polymerizable compound having a polar group and a polymerizable group on a cellulose acylate support An optical film having a retardation layer in which an alignment state of a liquid crystal material is fixed on the acrylic layer.
[2]
[1] The optical film according to [1], wherein the acrylic compound is a polyfunctional acrylate having 2 to 4 polymerizable groups on average.
[3]
The optical film according to [1] or [2], wherein the acrylic layer and the retardation layer are adjacent to each other.
[4]
The optical film according to any one of [1] to [3], wherein the retardation layer contains a fluorine atom.
[5]
The optical film according to any one of [1] to [4], wherein the retardation layer contains any element of a boron atom, a bromine atom, a nitrogen atom, and a sulfur atom.
[6]
The optical film according to any one of [1] to [5], wherein the retardation layer is obtained by polymerizing a rod-like polymerizable liquid crystal compound having an ethylenically unsaturated bond at both ends of a rigid group.
[7]
The optical film according to [6], wherein the rod-like polymerizable liquid crystal compound is composed of a benzoate ester compound derivative.
[8]
The optical film according to [6] or [7], wherein the rod-like polymerizable liquid crystal compound forming the retardation layer is fixed in a homeotropic alignment state.
[9]
Any of [1] to [8], wherein the ratio of the polymerizable compound having a polar group and a polymerizable group contained in the acrylic layer is 30% by mass or more based on the total of the polyhydric alcohol compound. 2. The optical film according to item 1.

[10]
The optical film according to any one of [1] to [9], wherein the acrylic compound and the polymerizable compound are the same compound.
[11]
The optical film according to any one of [1] to [10], wherein the cellulose acylate is cellulose acetate.
[12]
The optical film according to any one of [1] to [11], wherein the cellulose acylate has an average acyl substitution degree of 2.0 to 2.9.
[13]
The retardation value Re in the in-plane direction of the support is 70 to 150, and the retardation value Rth in the film thickness direction is 70 to 200, according to any one of [1] to [12]. Optical film.
[14]
The optical film according to any one of [1] to [13], wherein the support has a thickness of 5 to 50 μm.
[15]
The optical film according to any one of [1] to [14], wherein the acrylic layer has a thickness of 0.15 to 2.0 μm.
[16]
The optical film according to any one of [1] to [15], wherein the thickness of the retardation layer is 0.5 to 2.0 μm.
[17]
The optical film according to any one of [1] to [16], wherein a total film thickness of all layers including the support, the acrylic layer, and the retardation layer is 20 to 50 µm.
[18]
A polymerizable composition comprising an acrylic compound in which at least one hydroxyl group of a polyhydric alcohol compound is substituted with a (meth) acryloyl group and a polymerizable compound having a polar group and a polymerizable group is coated on a cellulose acylate support. A step of forming an acrylic layer by film curing by heat or ultraviolet irradiation, a step of applying a polymerizable composition containing a polymerizable liquid crystal compound on the acrylic layer, and heat after orienting the polymerizable liquid crystal compound. Or the manufacturing method of an optical film which has the process of fixing an orientation state by ultraviolet irradiation.

With the optical film of the present invention, a film excellent in the adhesion of the support, the acrylic layer and the retardation layer, the liquid crystal orientation of the retardation layer in which the orientation state of the liquid crystal material is fixed, and the retardation layer surface can be obtained.
In addition, since the optical film of the present invention can be easily thinned, it can contribute to thinning of a retardation film, a polarizing plate, and a liquid crystal display device.
Furthermore, an optical film provided with a hydrophilic acrylic layer as an intermediate layer is excellent in durability under a high-temperature and high-humidity environment and has a good surface shape. Moreover, since the hardness of the acrylic layer is larger than that of the PVA alignment film, film deformation is unlikely to occur in the wound shape when the film is continuously formed, and irregularities such as curl and transfer of steps that are likely to occur in the normal wound shape ( It is possible to obtain a high-quality film with few defective parts with good handling properties such as being difficult to cause nicks and tapes).

  Hereinafter, the present invention will be described in detail. In the present specification, when numerical values represent physical property values, characteristic values, etc., the descriptions “(numerical value 1) to (numerical value 2)” and “(numerical value 1) to (numerical value 2)” are “(numerical value 1). ) ”(Numerical value 2) or less”. In the present specification, the description “(meth) acrylate” means “at least one of acrylate and methacrylate”. The same applies to “(meth) acrylic acid”, “(meth) acryloyl” and the like.

  The optical film of the present invention comprises an acrylic compound obtained by substituting at least one hydroxyl group of a polyhydric alcohol compound with a (meth) acryloyl group on a cellulose acylate support, and a polymerizable compound having a polar group and a polymerizable group. It has an acrylic layer to be contained, and a retardation layer in which the alignment state of the liquid crystal material is fixed on the acrylic layer.

<Support>
The support body which contains the cellulose acylate which the optical film of this invention has is demonstrated.

[Cellulose acylate]
Examples of the cellulose acylate include a cellulose acylate compound and a compound having an acyl-substituted cellulose skeleton obtained by introducing a functional group biologically or chemically using cellulose as a raw material.

  Cellulose acylate is an ester of cellulose and acid. As the acid constituting the ester, an organic acid is preferable, a carboxylic acid is more preferable, a fatty acid having 2 to 22 carbon atoms is more preferable, and a cellulose acylate which is a lower fatty acid having 2 to 4 carbon atoms is the most. preferable.

[Cellulose acylate raw material cotton]
Cellulose acylate raw material cellulose used in the present invention includes cotton linter and wood pulp (hardwood pulp, softwood pulp), etc., and any cellulose acylate obtained from any raw material cellulose can be used, optionally mixed. May be. Detailed descriptions of these raw material celluloses can be found in, for example, “Plastic Materials Course (17) Fibrous Resin” (Marusawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Publication Technical Report 2001-1745 ( 7 to 8) can be used, and the cellulose acylate of the present invention is not particularly limited.

[Substitution degree of cellulose acylate]
The cellulose acylate according to the present invention is obtained by acylating a hydroxyl group of cellulose, and any substituents from an acetyl group having 2 carbon atoms to an acyl group having 22 carbon atoms can be used.
The cellulose acylate in the present invention preferably has an average acyl substitution degree of 2.0 to 2.9, and more preferably 2.20 to 2.85.
In the cellulose acylate, the degree of substitution of cellulose with hydroxyl groups is not particularly limited, but the degree of substitution of acetic acid and / or fatty acids having 3 to 22 carbon atoms substituted with hydroxyl groups of cellulose is measured, and the degree of substitution is calculated. Can be obtained. As a measuring method, it can carry out according to ASTM D-817-91.

  An acyl substitution degree of 2.00 or more is sufficient in terms of humidity stability and polarizing plate durability, and an acyl substitution degree of 2.9 or less results in solubility in an organic solvent and polycondensation. Cellulose acylate having excellent compatibility with the body can be obtained, which is preferable.

  The acyl group of cellulose acylate is not particularly limited and may be an aliphatic group or an aryl group, and may be a single group or a mixture of two or more types. The acyl group preferably has 2 to 22 carbon atoms, for example, an alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, or aromatic alkylcarbonyl ester of cellulose, each having a further substituted group. Good. These preferred acyl groups 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 I-butanoyl group, t-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, t-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are preferable, and acetyl group, propionyl group, butanoyl group are preferable. Groups are more preferred. Further preferred groups are an acetyl group and a propionyl group, and the most preferred group is an acetyl group.

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

  The molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) is small, and the molecular weight A narrow distribution is preferred. The specific value of Mw / Mn is preferably 1.0 to 4.0, more preferably 2.0 to 4.0, and most preferably 2.3 to 3.4. preferable.

[Manufacture of cellulose acylate film]
The support included in the optical film of the present invention is preferably a cellulose acylate film containing the cellulose acylate.
The method for producing a cellulose acylate film includes a film-forming step of casting a dope on a support and evaporating the solvent to form a cellulose acylate film, a stretching step of stretching the film, and a film obtained thereafter It is preferable to have a drying step for drying the substrate, and further a heat treatment for 1 minute or more at a temperature of 150 to 200 ° C. after the drying step.

(Film forming process)
In the present invention, a method for producing a known cellulose acylate film or the like can be widely adopted, and it is preferably produced by a solvent cast method. In the solvent cast method, a film can be produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent.
The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Methylene chloride is a representative halogenated hydrocarbon.
Two or more organic solvents may be mixed and used.

A cellulose acylate solution can be prepared by a general method. A general method means processing at a temperature of 0 ° C. or higher (ordinary temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent.
The amount of cellulose acylate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent).
The solution can be prepared by stirring the cellulose acylate and the organic solvent at room temperature (0 to 40 ° C.). The high concentration solution may be stirred under pressure and heating conditions. Specifically, the cellulose acylate and the organic solvent are placed in a pressure vessel and sealed, and stirred while being heated to a temperature equal to or higher than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially. The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.
When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

From the prepared cellulose acylate solution (dope), a cellulose acylate film can be produced by a solvent cast method.
The dope is cast on a drum or band to form a film, 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 band is preferably finished in a mirror state. Regarding casting and drying methods in the solvent cast method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,37,069, 2,273,070, 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 band 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 the drum or band and further dried with 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 band during casting.

(Co-casting)
The cellulose acylate film of the present invention is preferably produced by stretching after film formation by a solution casting film formation method. Moreover, it is preferable that a solution casting film is a multilayer casting film by co-casting simultaneously or sequentially. It is because it can be set as the film which has a desired retardation value.
In the present invention, the obtained cellulose acylate solution may be cast as a single layer liquid on a smooth band or drum as a metal support, or a plurality of cellulose acylate solutions of two or more layers may be cast. May be. When casting a plurality of cellulose acylate solutions, produce a film while casting and laminating a solution containing cellulose acylate from a plurality of casting openings provided at intervals in the traveling direction of the metal support. For example, the methods described in JP-A-61-158414, JP-A-1-122419, JP-A-11-198285 and the like 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 ester solution to be cast may be the same solution or different cellulose acylate solutions, and is 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. Further, the cellulose ester solution of the present invention may be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, and a polarizing layer).

  In conventional single-layer liquids, it is preferable to extrude a cellulose acylate solution with a high concentration and a high viscosity in order to obtain the required film thickness. In this case, the stability of the cellulose acylate solution is poor and solids are generated. In many cases, however, it becomes a problem due to a failure or poor flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also a concentrated cellulose acylate solution can be used to reduce the drying load and increase the film production speed.

  In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, and more preferably 2 to 30%. Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness.

In the case of co-casting, a cellulose acylate solution having a different substitution degree can be co-cast to produce a cellulose ester film having a laminated structure.
In addition, a cellulose acylate film having a laminated structure can be produced by co-casting cellulose acylate solutions having different additive concentrations such as a plasticizer, an ultraviolet absorber, and a matting agent described later. For example, the matting agent can be contained in the surface layer in a large amount or only in the surface layer. The plasticizer and the ultraviolet absorber can be contained in the inner layer more than the surface layer, and may be contained only in the inner layer. Also, the type of plasticizer and UV absorber can be changed between the inner layer and the surface layer. For example, the surface layer contains a low-volatile plasticizer and / or UV absorber, and the inner layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect that a release agent is included only in the surface layer on the metal support side. Moreover, in order to cool a metal support body by a cooling drum method and to gelatinize a solution, it is also preferable to add more alcohol which is a poor solvent to a surface layer than an internal layer. The Tg of the surface layer and the inner layer may be different, and the Tg of the inner layer is preferably lower than the Tg of the surface layer. The viscosity of the solution containing cellulose acylate during casting may be different between the surface layer and the inner layer, and the viscosity of the surface layer is preferably smaller than the viscosity of the inner layer. It may be smaller than the viscosity.

(Drying process, stretching process)
A method for drying a web that has been dried on a drum or belt and peeled off will be described. The web peeled at the peeling position just before the drum or belt makes one round is conveyed by alternately passing through a group of rolls arranged in a staggered manner, or the both ends of the peeled web are gripped by clips or the like and are not contacted. It is conveyed by the method of conveying it automatically. Drying is performed by a method of applying wind at a predetermined temperature to both sides of the web (film) being conveyed or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds. In the drying process after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, as shown in Japanese Patent Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferable. It is preferable that the drying temperature in the said drying process is 100-145 degreeC. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, but may be appropriately selected according to the type and combination of the solvents used. In the production of the film of the present invention, the web (film) peeled from the support is preferably stretched when the amount of residual solvent in the web is less than 120% by mass.

The residual solvent amount can be expressed by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the web of which M is measured is dried at 110 ° C. for 3 hours. If the amount of residual solvent in the web is too large, the effect of stretching cannot be obtained, and if it is too small, stretching becomes extremely difficult and the web may break. The more preferable range of the residual solvent amount in the web is 70% by mass or less, more preferably 10% by mass to 50% by mass, and particularly preferably 12% by mass to 35% by mass. Further, if the stretching ratio is too small, a sufficient phase difference cannot be obtained, and if it is too large, stretching may become difficult and breakage may occur.
The draw ratio is preferably 1.3 to 1.9, and more preferably 1.4 to 1.7.
The stretching may be performed in the longitudinal direction, in the transverse direction, or in both directions, preferably at least in the longitudinal direction. The cellulose ester film of the present invention is obtained by stretching in the width direction, and the stretching ratio is preferably 5% or more and 100% or less in the direction perpendicular to the transport direction. By setting the draw ratio to 30% or more, Re can be expressed more appropriately, and the bowing can be improved. Moreover, by setting the draw ratio to 70% or less, a film having a tear strength of 3 or more can be obtained while the haze is lowered. In the present invention, the solution cast film can be stretched without being heated to a high temperature as long as the residual solvent amount is in a specific range, but it is preferable because drying and stretching can shorten the process. . However, since the plasticizer volatilizes when the temperature of the web is too high, a range of room temperature (15 ° C) to 145 ° C or less is preferable. Further, stretching in the biaxial directions perpendicular to each other is an effective method for bringing the refractive indexes Nx, Ny, and Nz of the film within the scope of the present invention. For example, when stretching in the casting direction, if the shrinkage in the width direction is too large, the value of Nz becomes too large. In this case, it can be improved by suppressing the width shrinkage of the film or stretching in the width direction. When stretching in the width direction, the refractive index may be distributed with a width. This is sometimes seen when using, for example, the tenter method, but it is a phenomenon that occurs when the film is stretched in the width direction and contraction force is generated at the center of the film and the end is fixed. It is thought to be called the Boeing phenomenon. Even in this case, by stretching in the casting direction, the bowing phenomenon can be suppressed, and the distribution of the width retardation can be improved. Furthermore, the film thickness fluctuation | variation of the film obtained by extending | stretching to the biaxial direction orthogonal to each other can be reduced. If the film thickness variation of the optical film is too large, the retardation will be uneven. The film thickness variation of the optical film is preferably in the range of ± 3%, and more preferably ± 1%. For the purposes as described above, a method of stretching in the biaxial directions orthogonal to each other is effective, and the stretching ratios in the biaxial directions orthogonal to each other are 1.2 to 2.0 times and 0.7 to 1.0, respectively. It is preferable that the range be doubled. Here, stretching to 1.2 to 2.0 times with respect to one direction and making the other perpendicular to 0.7 to 1.0 times means that the distance between the clip or pin supporting the film is This means that the distance is 0.7 to 1.0 times the interval before stretching.

In general, when a biaxial stretching tenter is used to stretch in the width direction so as to have an interval of 1.2 to 2.0 times, a contracting force acts in the longitudinal direction, which is the perpendicular direction.
Therefore, if the force is applied in only one direction and the stretching is continued, the width in the perpendicular direction is reduced, but this means that the amount of shrinkage is suppressed with respect to the amount that shrinks without restricting the width. This means that the interval between the clip or pin whose width is restricted is restricted to a range of 0.7 to 1.0 times that before stretching. At this time, in the longitudinal direction, a force is exerted to shrink the film by stretching in the width direction. By taking the interval between the clips or pins in the longitudinal direction, an excessive tension is not applied in the longitudinal direction. There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination. In the case of the so-called tenter method, driving the clip portion by a linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

(Heat treatment process)
The film production method of the present invention is preferably provided with a heat treatment step after the drying step. The heat treatment in the heat treatment step may be performed after completion of the drying step, and may be performed immediately after the stretching / drying step. Alternatively, after the completion of the drying step, the material may be wound once by a method described later, and only the heat treatment step may be separately provided. . In the present invention, it is preferable to provide the heat treatment step again after the drying step is once cooled to room temperature to 100 ° C. or less. This is because a film having better thermal dimensional stability can be obtained. For the same reason, it is preferable that the amount of residual solvent is dried to less than 2% by mass, preferably less than 0.4% by mass immediately before the heat treatment step.
Although the reason why the shrinkage rate of the film can be reduced by such treatment is not clear, in the film that has undergone the treatment to be stretched in the stretching process, the residual stress in the stretching direction is large, so the residual stress is eliminated by heat treatment. Thus, it is presumed that the shrinkage force in the region below the heat treatment temperature is reduced.

The heat treatment is performed by a method of applying a wind at a predetermined temperature to the film being conveyed or a method using a heating means such as a microwave.
The heat treatment is preferably performed at a temperature of 150 to 200 ° C., more preferably 160 to 180 ° C. The heat treatment is preferably performed for 1 to 20 minutes, more preferably 5 to 10 minutes.
When the heat treatment temperature exceeds 200 ° C. for a long time, it may cause a problem because the amount of the plasticizer scattered in the film increases.

  In the heat treatment step, the film tends to shrink in the longitudinal direction or the width direction. It is preferable to heat-treat while suppressing the shrinkage as much as possible in order to improve the flatness of the finished film, and a method in which the width ends of the web are held with clips or pins in the width direction (tenter method). Is preferred. Furthermore, it is preferable to extend | stretch 0.9 to 1.5 times in the width direction and conveyance direction of a film, respectively.

  As the winder for winding the obtained film, a commonly used winder can be used, such as a constant tension method, a constant torque method, a taper tension method, and a program tension control method with a constant internal stress. It can be wound up by a take-up method. In the optical film roll obtained as described above, the slow axis direction of the film is preferably ± 2 ° with respect to the winding direction (longitudinal direction of the film), and further within the range of ± 1 °. Preferably there is. Alternatively, it is preferably ± 2 degrees with respect to the direction perpendicular to the winding direction (film width direction), and more preferably within a range of ± 1 degree. In particular, the slow axis direction of the film is preferably within ± 0.1 degrees with respect to the winding direction (longitudinal direction of the film). Alternatively, it is preferably within ± 0.1 degrees with respect to the width direction of the film.

[Heating steam treatment]
In addition, the stretched film may be manufactured through a process of spraying water vapor heated to 100 ° C. or higher. By passing through this water vapor spraying step, the residual stress of the cellulose acylate film to be produced is relaxed, and the dimensional change is reduced, which is preferable. The temperature of the water vapor is not particularly limited as long as it is 100 ° C. or higher, but considering the heat resistance of the film, the temperature of the water vapor is 200 ° C. or lower.

  These steps from casting to post-drying may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen gas. The winder used for producing the cellulose ester film of the present invention may be a commonly used winder such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress. Can be rolled up.

(Film thickness)
The film thickness of the cellulose acylate film that is the support in the optical film of the present invention is preferably 5 μm to 100 μm, and more preferably 5 to 50 μm. A film thickness of 20 μm or more is preferable from the viewpoint of handling properties when processing into a polarizing plate and curling of the polarizing plate. The film thickness unevenness of the cellulose ester film of the present invention is preferably 0 to 2% in both the transport direction and the width direction, more preferably 0 to 1.5%, and more preferably 0 to 1%. Particularly preferred.

(Retardation of cellulose acylate film)
In the present specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ. Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) by making light of wavelength λ nm incident in the normal direction of the film. Rth was measured by making light having a wavelength λ nm incident from a direction inclined + 40 ° with respect to the normal direction of the film with the slow axis in the plane (determined by KOBRA 21ADH) as the tilt axis (rotation axis). A retardation value and a retardation value measured by making light of wavelength λ nm incident from a direction inclined by −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis). KOBRA 21ADH is calculated based on the retardation value measured in the direction. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

The cellulose acylate film is preferably used as a protective film for a polarizing plate, and can be particularly preferably used as a retardation film corresponding to various liquid crystal modes.
The cellulose acylate film preferably has Re of 30 to 200 nm, more preferably 30 to 150 nm, and still more preferably 70 to 150 nm. Rth is preferably 70 to 400 nm, and more preferably 70 to 300 nm.
From the viewpoint of application to an IPS mode liquid crystal display device, Re of the support is preferably 70 nm to 150 nm, and Rth is preferably 70 nm to 200 nm.
Here, Re and Rth are an in-plane retardation value and a retardation value in the thickness direction, respectively, measured with light having a wavelength of 550 nm at 25 ° C. and 60% RH.

(Additive)
The support in the present invention preferably contains at least one compound selected from the group consisting of i) and ii) below.
i) a polycondensed ester containing a dicarboxylic acid residue having an average carbon number of 5.5 or more and 10.0 or less containing at least one aromatic dicarboxylic acid residue ii) a pyranose in which at least one hydroxyl group is aromatically esterified Sugar ester containing 1 to 12 structures or furanose structures

  Although the compounds of i) and ii) have a function as a plasticizer, a retardation film including a cellulose acylate film obtained by adding these compounds to the aforementioned cellulose acylate is used as a polarizing plate protective film. Thus, the durability of the polarizer can be improved.

[I) Polycondensed ester]
i) A polycondensation ester (also referred to as “i) polycondensation ester” containing a dicarboxylic acid residue having an average carbon number of 5.5 or more and 10.0 or less containing at least one aromatic dicarboxylic acid residue will be described. .
i) The polycondensed ester is obtained from at least one dicarboxylic acid having an aromatic ring (also referred to as aromatic dicarboxylic acid) and at least one diol.

(Aromatic dicarboxylic acid residue)
The aromatic dicarboxylic acid residue is contained in a polycondensed ester obtained from a diol and a dicarboxylic acid containing an aromatic dicarboxylic acid.
In the present specification, a residue is a partial structure of a polycondensed ester and represents a partial structure having the characteristics of a monomer forming the polycondensed ester. For example, the dicarboxylic acid residue formed from dicarboxylic acid HOOC-R-COOH (R represents a hydrocarbon group) is -OC-R-CO-.
The content ratio of the aromatic dicarboxylic acid residue in the polycondensed ester is preferably 40 mol% or more, more preferably 40 mol% to 95 mol%, still more preferably 45 mol% to 70 mol%, and more preferably 50 mol% to It is especially preferable that it is 70 mol%.
By setting the aromatic dicarboxylic acid residue ratio to 40 mol% or more, a cellulose acylate film exhibiting sufficient optical anisotropy can be obtained, and a polarizing plate excellent in durability can be obtained. Moreover, if it is 95 mol% or less, it is excellent in compatibility with a cellulose acylate, and it can make it hard to produce a bleed-out also at the time of film formation of a cellulose acylate film and the time of heat-stretching.

Examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8-naphthalenedicarboxylic acid or Examples include 2,6-naphthalenedicarboxylic acid. Phthalic acid, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred, phthalic acid and terephthalic acid are more preferred, and terephthalic acid is even more preferred.
In the polycondensed ester, an aromatic dicarboxylic acid residue is formed by the aromatic dicarboxylic acid used for mixing.
Specifically, the aromatic dicarboxylic acid residue preferably includes at least one of a phthalic acid residue, a terephthalic acid residue, and an isophthalic acid residue, more preferably a phthalic acid residue or a terephthalic acid residue. It contains at least one, and more preferably contains a terephthalic acid residue.
By using terephthalic acid as the aromatic dicarboxylic acid, it is possible to obtain a cellulose ester film that is more excellent in compatibility with the cellulose ester and hardly causes bleed-out even when the cellulose ester film is formed and heated and stretched. Moreover, aromatic dicarboxylic acid may be used alone or in combination of two or more. When two types are used, it is preferable to use phthalic acid and terephthalic acid.
The combined use of two types of aromatic dicarboxylic acids, phthalic acid and terephthalic acid, is preferable in that the polycondensation ester at room temperature can be softened and handling becomes easy.
The content of the terephthalic acid residue in the dicarboxylic acid residue of the polycondensed ester is preferably 40 mol% to 95 mol%, preferably 45 mol% to 70 mol%, and preferably 50 mol% to 70 mol%. .
By setting the terephthalic acid residue ratio to 40 mol% or more, a cellulose ester film exhibiting sufficient optical anisotropy can be obtained. Moreover, if it is 95 mol% or less, it is excellent in compatibility with a cellulose ester, and it can make it hard to produce a bleed-out also at the time of film forming of a cellulose ester film, and the time of heat-stretching.

(Aliphatic dicarboxylic acid residue)
i) The polycondensation ester may contain an aliphatic dicarboxylic acid residue in addition to the aromatic dicarboxylic acid residue.
The aliphatic dicarboxylic acid residue is contained in a polycondensed ester obtained from a diol and a dicarboxylic acid containing an aliphatic dicarboxylic acid.
Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid or 1,4- And cyclohexanedicarboxylic acid.
The aliphatic dicarboxylic acid may be used alone or in combination of two or more. When two kinds are used, it is preferable to use succinic acid and adipic acid. When using 1 type, it is preferable to use a succinic acid. This is preferable in terms of compatibility with the cellulose acylate because the average carbon number of the diol residue can be adjusted to a desired value.

  i) The average carbon number of the dicarboxylic acid residue contained in the polycondensed ester is 5.5 or more and 10.0 or less. The dicarboxylic acid residue preferably has an average carbon number of 5.5 to 8.0, and more preferably 5.5 to 7.0. If the average carbon number of the dicarboxylic acid residue is 5.5 or more, a polarizing plate having excellent durability can be obtained. If the average carbon number of the dicarboxylic acid residue is 10.0 or less, the compatibility with cellulose acylate is excellent, and the occurrence of bleed-out can be suppressed in the process of forming a cellulose acylate film.

  The average carbon number of the dicarboxylic acid residue is calculated by multiplying the constituent carbon number by the composition ratio (molar fraction) of the dicarboxylic acid residue as the average carbon number. For example, when the adipic acid residue and the phthalic acid residue are composed of 50 mol% each, the average carbon number is 7.0. The same applies to a diol residue. The average carbon number of an aliphatic diol residue is a value calculated by multiplying the constituent carbon number by the composition ratio (molar fraction) of the aliphatic diol residue. For example, when it is composed of 50 mol% of ethylene glycol residues and 50 mol% of 1,2-propanediol residues, the average carbon number is 2.5.

(Aliphatic diol)
The aliphatic diol residue is contained in a polycondensed ester obtained from an aliphatic diol and a dicarboxylic acid containing a dicarboxylic acid.
In the present specification, a residue is a partial structure of a polycondensed ester and represents a partial structure having the characteristics of a monomer forming the polycondensed ester. For example, the diol residue formed from the diol HO—R—OH is —O—R—O—.
Examples of the diol that forms the polycondensed ester include aromatic diols and aliphatic diols, including at least aliphatic diols.
The polycondensed ester contains an aliphatic diol residue having an average carbon number of 2.5 or more and 7.0 or less. An aliphatic diol residue having an average carbon number of 2.5 or more and 4.0 or less is preferable. When the average carbon number of the aliphatic diol residue is larger than 3.0, the compatibility with the cellulose ester is low, the bleedout is likely to occur, the weight loss of the compound is increased, and the cellulose acylate web is dried. Planar failures occur that may be caused by contamination. In addition, if the aliphatic diol residue has an average carbon number of less than 2.0, the synthesis becomes difficult, so it cannot be used.
Examples of the aliphatic diol used in the present invention include alkyl diols and alicyclic diols, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3- Methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl -1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, diethylene glycol, cyclohexanedimethanol, etc. Is preferably used together with ethylene glycol as one or a mixture of two or more.

The preferred aliphatic diol is at least one of ethylene glycol, 1,2-propanediol, and 1,3-propanediol, and particularly preferably at least one of ethylene glycol and 1,2-propanediol. . When two types are used, it is preferable to use ethylene glycol and 1,2-propanediol. By using 1,2-propanediol or 1,3-propanediol, crystallization of the polycondensed ester can be prevented.
In the polycondensed ester, a diol residue is formed by the diol used for mixing.
The diol residue preferably includes at least one of an ethylene glycol residue, a 1,2-propanediol residue, and a 1,3-propanediol residue, and an ethylene glycol residue or a 1,2-propanediol residue It is more preferable that
Of the aliphatic diol residues, the ethylene glycol residue is preferably 20 mol% to 100 mol%, and more preferably 50 mol% to 100 mol%.

(Sealing)
The terminal of the polycondensed ester of the present invention is not capped and remains a diol or carboxylic acid, or may be further reacted with a monocarboxylic acid or monoalcohol to carry out so-called terminal capping.
As monocarboxylic acids used for sealing, acetic acid, propionic acid, butanoic acid and the like are preferable, acetic acid or propionic acid is more preferable, and acetic acid is most preferable. As monoalcohols used for sealing, methanol, ethanol, propanol, isopropanol, butanol, isobutanol and the like are preferable, and methanol is most preferable. When the number of carbon atoms of the monocarboxylic acid used at the terminal of the polycondensed ester is 3 or less, the loss on heating of the compound does not increase, and no surface failure occurs.
More preferably, the terminal of the polycondensed ester of the present invention is not sealed and remains a diol residue, or is more preferably sealed with acetic acid or propionic acid.
Both ends of the polycondensed ester according to the present invention may be sealed or unsealed.
When both ends of the condensate are unsealed, the polycondensed ester is preferably a polyester polyol.
One aspect of the polycondensed ester according to the present invention is a polycondensed ester in which the aliphatic diol residue has 2.5 to 7.0 carbon atoms and both ends of the condensate are unblocked. Can do.
When both ends of the condensate are sealed, it is preferably sealed by reacting with a monocarboxylic acid. At this time, both ends of the polycondensed ester are monocarboxylic acid residues. In the present specification, a residue is a partial structure of a polycondensed ester and represents a partial structure having the characteristics of a monomer forming the polycondensed ester. For example, the monocarboxylic acid residue formed from monocarboxylic acid R—COOH is R—CO—. It is preferably an aliphatic monocarboxylic acid residue, more preferably an aliphatic monocarboxylic acid residue having 22 or less carbon atoms, and an aliphatic monocarboxylic acid residue having 3 or less carbon atoms. More preferably it is. In addition, an aliphatic monocarboxylic acid residue having 2 or more carbon atoms is preferable, and an aliphatic monocarboxylic acid residue having 2 carbon atoms is particularly preferable.
One aspect of the polycondensation ester according to the present invention is a polycondensation ester in which the aliphatic diol residue has a carbon number of greater than 2.5 and no greater than 7.0, and both ends of the condensate are monocarboxylic acid residues. Can be mentioned.
When the number of carbon atoms of the monocarboxylic acid residue at both ends of the polycondensed ester is 3 or less, the volatility is lowered, the weight loss due to heating of the polycondensed ester does not increase, and process contamination and surface failure occur Can be reduced.
That is, the monocarboxylic acid used for sealing is preferably an aliphatic monocarboxylic acid. More preferably, the monocarboxylic acid is an aliphatic monocarboxylic acid having 2 to 22 carbon atoms, more preferably an aliphatic monocarboxylic acid having 2 to 3 carbon atoms, and an aliphatic monocarboxylic acid residue having 2 carbon atoms. Particularly preferred is a group.
For example, acetic acid, propionic acid, butanoic acid, benzoic acid and derivatives thereof are preferable, acetic acid or propionic acid is more preferable, and acetic acid is most preferable.
Two or more monocarboxylic acids used for sealing may be mixed.
Both ends of the polycondensed ester of the present invention are preferably sealed with acetic acid or propionic acid, and most preferably both ends become acetyl ester residues (sometimes referred to as acetyl residues) by acetic acid sealing.
When both ends are sealed, the state at normal temperature is unlikely to be in a solid form, the handling is good, and a cellulose ester film excellent in humidity stability and polarizing plate durability can be obtained.

The number average molecular weight of the polycondensed ester is preferably 500 to 2000, more preferably 600 to 1500, and still more preferably 700 to 1200. If the number average molecular weight of the polycondensed ester is 600 or more, the volatility is low, and film failure or process contamination due to volatilization under high temperature conditions during stretching of the cellulose ester film is unlikely to occur. Moreover, if it is 2000 or less, compatibility with a cellulose ester will become high, and it will become difficult to produce the bleed-out at the time of film forming and the heat-stretching.
The number average molecular weight of the polycondensed ester of the present invention can be measured and evaluated by gel permeation chromatography. Further, in the case of a polyester polyol having an unsealed terminal, it can also be calculated from the amount of hydroxyl group per weight (hereinafter referred to as hydroxyl value). The hydroxyl value is determined by measuring the amount (mg) of potassium hydroxide required for neutralizing excess acetic acid after acetylating the polyester polyol.

  In Table 1 below, specific examples A-1 to A-31, B-3, B-4, B-6, B-9, B-10 of the polycondensation ester according to the present invention and the weight outside the scope of the present invention are shown. Specific examples B-1, B-2, B-5, B-7, and B-8 of the condensed ester are described, but are not limited thereto.

  The synthesis of the polycondensed ester is carried out by a conventional method such as a hot melt condensation method by a polyesterification reaction or transesterification reaction between a diol and a dicarboxylic acid, or an interfacial condensation method between an acid chloride of these acids and a glycol. Can also be easily synthesized. In addition, the polycondensed ester according to the present invention is described in detail in Koichi Murai, “Plasticizer Theory and Application” (Kokai Shobo Co., Ltd., first edition issued on March 1, 1973). In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 2007-003679. The materials described in each publication can also be used.

  The content of the polycondensed ester in the cellulose acylate film is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, and 5 to 20% by mass with respect to the cellulose acylate. Is more preferable.

The content of the raw material aliphatic diol, dicarboxylic acid ester, or diol ester contained in the polycondensed ester in the cellulose ester film is preferably less than 1% by mass, and more preferably less than 0.5% by mass. Examples of the dicarboxylic acid ester include dimethyl phthalate, di (hydroxyethyl) phthalate, dimethyl terephthalate, di (hydroxyethyl) terephthalate, di (hydroxyethyl) adipate, and di (hydroxyethyl) succinate. Examples of the diol ester include ethylene diacetate and propylene diacetate.
The kind and ratio of each of the dicarboxylic acid residue, diol residue, and monocarboxylic acid residue contained in the polycondensation ester used in the present invention can be measured by a usual method using H-NMR. . Usually, deuterated chloroform can be used as a solvent.
The number average molecular weight of the polycondensed ester can be measured by a usual method using GPC (Gel Permeation Chromatography), and polystyrene can be usually used as a standard material.
For measurement of the hydroxyl value of the polycondensed ester, the acetic anhydride method described in Japanese Industrial Standard JIS K3342 (discontinued) can be applied. When the polycondensate is a polyester polyol, the hydroxyl value is preferably from 50 to 190, and more preferably from 50 to 130.

[Ii) sugar ester]
ii) A sugar ester containing 1 to 12 pyranose structures or furanose structures in which at least one hydroxyl group is aromatically esterified (also referred to as “ii) sugar ester”) will be described.
By adding the sugar ester compound to the cellulose acylate film, the development of optical properties is not impaired, and the internal haze when the wet heat treatment is performed after stretching is not deteriorated. Furthermore, the front contrast can be greatly improved by using the cellulose acylate film of the present invention in a liquid crystal display device.

-Sugar residue-
The sugar ester compound is a compound in which at least one substitutable group (for example, hydroxyl group, carboxyl group) in the monosaccharide or polysaccharide constituting the compound and at least one substituent group are ester-bonded. Say that. That is, the sugar ester compound referred to here includes a wide range of sugar derivatives, for example, a compound containing a sugar residue such as gluconic acid as a structure. That is, the sugar ester compound includes an ester of glucose and carboxylic acid and an ester of gluconic acid and alcohol.
The substitutable group in the monosaccharide or polysaccharide constituting the sugar ester compound is preferably a hydroxyl group.

  The sugar ester compound includes a structure derived from a monosaccharide or a polysaccharide constituting the sugar ester compound (hereinafter also referred to as a sugar residue). The structure of the sugar residue per monosaccharide is referred to as the structural unit of the sugar ester compound. The structural unit of the sugar ester compound preferably includes a pyranose structural unit or a furanose structural unit, and more preferably all sugar residues are a pyranose structural unit or a furanose structural unit. Further, when the sugar ester is composed of a polysaccharide, it preferably contains both a pyranose structural unit or a furanose structural unit.

  The sugar residue of the sugar ester compound may be derived from 5 monosaccharides or 6 monosaccharides, but is preferably derived from 6 monosaccharides.

  The number of structural units contained in the sugar ester compound is preferably 1 to 12, more preferably 1 to 6, and particularly preferably 1 or 2.

  In the present invention, the sugar ester compound is more preferably a sugar ester compound containing 1 to 12 pyranose structural units or furanose structural units in which at least one hydroxyl group is esterified, and at least one of the hydroxyl groups is an ester. More preferably, it is a sugar ester compound containing one or two pyranose structural units or furanose structural units.

  Examples of the monosaccharide or saccharide containing 2 to 12 monosaccharide units include, for example, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, fructose, mannose, gulose, idose, galactose , Talose, trehalose, isotrehalose, neotrehalose, trehalosamine, caudibiose, nigerose, maltose, maltitol, isomaltose, sophorose, laminaribiose, cellobiose, gentiobiose, lactose, lactosamine, lactitol, lactulose, melibiose, primebelloose, rutiose , Sucrose, sucralose, turanose, vicyanose, cellotriose, cacotriose, gentianose, isomaltoto Ose, isopanose, maltotriose, manninotriose, melezitoose, panose, planteose, raffinose, solatriose, umbelliferose, lycotetraose, maltotetraose, stachyose, baltopentaose, velval course, maltohexaose, Examples include α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, δ-cyclodextrin, xylitol, sorbitol and the like.

  Preferably, ribose, arabinose, xylose, lyxose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, sucralose, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, δ-cyclodextrin Xylitol, sorbitol, more preferably arabinose, xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, β-cyclodextrin, γ-cyclodextrin, particularly preferably xylose, glucose, fructose , Mannose, galactose, maltose, cellobiose, sucrose, xylitol, sorbitol. The sugar ester compound has a glucose skeleton or a sucrose skeleton, and is described in JP-A 2009-1696 [0059] as Compound 5 and has a maltose skeleton used in the examples of the same document. Compared to an ester compound and the like, it is more preferable from the viewpoint of compatibility with a polymer.

-Substituent structure-
It is more preferable that the sugar ester compound used in the present invention has a structure represented by the following general formula (1) including the substituent used.
Formula _{(1) (OH) p -G-} (L 1 -R 11) q (O-R 12) r
In general formula (1), G represents a sugar residue, L ¹ represents any ^one of —O—, —CO—, and —NR ¹³ —, and R ¹¹ represents a hydrogen atom or a monovalent substituent. R ¹² represents a monovalent substituent bonded by an ester bond. p, q, and r each independently represent an integer of 0 or more, and p + q + r is equal to the number of hydroxyl groups on the assumption that G is an unsubstituted saccharide having a cyclic acetal structure.

  The preferable range of G is the same as the preferable range of the sugar residue.

L ¹ is preferably —O— or —CO—, and more preferably —O—. When L ¹ is —O—, it is particularly preferably a linking group derived from an ether bond or an ester bond, and more preferably a linking group derived from an ester bond.
Further, when there are a plurality of L ^{1 s} , they may be the same or different.

At least one of R ¹¹ and R ¹² preferably has an aromatic ring.

In particular, when L ¹ is —O— (that is, when R ¹¹ and R ¹² are substituted on the hydroxyl group in the sugar ester compound), R ¹¹ , R ¹² and R ¹³ are substituted or unsubstituted. Are preferably selected from the group consisting of acyl groups, substituted or unsubstituted aryl groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted amino groups, substituted or unsubstituted acyl groups, substituted or unsubstituted A substituted alkyl group or a substituted or unsubstituted aryl group is more preferable, and an unsubstituted acyl group, a substituted or unsubstituted alkyl group, or an unsubstituted aryl group is particularly preferable.
When there are a plurality of R ¹¹ , R ¹² and R ¹³ , they may be the same as or different from each other.

The p represents an integer of 0 or more, and the preferred range is the same as the preferred range of the number of hydroxyl groups per monosaccharide unit described later, but in the present invention, the p is preferably zero.
The r preferably represents a number larger than the number of pyranose structural units or furanose structural units contained in the G.
Q is preferably 0.
Moreover, since p + q + r is equal to the number of hydroxyl groups assuming that G is an unsubstituted saccharide having a cyclic acetal structure, the upper limit values of p, q and r are uniquely determined according to the structure of G. Is done.

  Preferred examples of the substituent of the sugar ester compound include an alkyl group (preferably an alkyl group having 1 to 22 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably an alkyl group having 1 to 8 carbon atoms, such as a methyl group, An ethyl group, a propyl group, a hydroxyethyl group, a hydroxypropyl group, a 2-cyanoethyl group, a benzyl group, etc.), an aryl group (preferably having a carbon number of 6 to 24, more preferably 6 to 18 and particularly preferably 6 to 12). A group such as a phenyl group or a naphthyl group, an acyl group (preferably having a carbon number of 1 to 22, more preferably a carbon number of 2 to 12, particularly preferably a carbon number of 2 to 8, such as an acetyl group or a propionyl group, Butyryl group, pentanoyl group, hexanoyl group, octanoyl group, benzoyl group, toluyl group, phthalyl group), amide group (preferred) Or an amide group (preferably 4 to 22 carbon atoms, more preferably an amide having 2 to 12 carbon atoms, particularly preferably an amide having 2 to 8 carbon atoms, such as a formamide group or an acetamide group). Is an amide group having 4 to 12 carbon atoms, particularly preferably 4 to 8 carbon atoms, such as a succinimide group and a phthalimide group, and an arylalkyl group (preferably having 7 to 25 carbon atoms, more preferably 7 to 19 carbon atoms, particularly Preferred examples include 7 to 13 aryl groups such as benzyl group. Among these, an alkyl group or an acyl group is more preferable, a methyl group, an acetyl group, a benzoyl group, or a benzyl group is more preferable, and an acetyl group and a benzyl group are particularly preferable. Furthermore, among them, when the constituent sugar of the sugar ester compound has a sucrose skeleton, a sugar ester compound having an acetyl group and a benzyl group as substituents is described as compound 3 in [0058] of JP2009-1696A. Therefore, it is more preferable from the viewpoint of compatibility with the polymer, compared with the sugar ester compound having a benzoyl group used in the examples of the document.

  The number of hydroxyl groups per structural unit in the sugar ester compound (hereinafter also referred to as hydroxyl group content) is preferably 3 or less, more preferably 1 or less, and zero. Particularly preferred. By controlling the hydroxyl group content within the above range, the migration of the sugar ester compound to the polarizer layer and the destruction of the PVA-iodine complex at high temperature and high humidity can be suppressed, and the deterioration of the polarizer performance at high temperature and high humidity can be prevented. It is preferable from the point of suppression.

The sugar ester compound used in the film of the present invention preferably has no unsubstituted hydroxyl group, and the substituent consists only of an acetyl group and / or a benzyl group.
The ratio of acetyl groups to benzyl groups in the sugar ester compound tends to increase the value of wavelength dispersion ΔRe and ΔRe / Re (550) of the cellulose acylate film obtained when the ratio of benzyl groups is somewhat small. The change in blackness when incorporated in a liquid crystal display device is small, which is preferable. Specifically, the ratio of the benzyl group to the sum of all unsubstituted hydroxyl groups and all substituents in the sugar ester compound is preferably 60% or less, and preferably 40% or less.

  As the method for obtaining the sugar ester compound, commercially available products such as those manufactured by Tokyo Chemical Industry Co., Ltd., Aldrich, etc., or known ester derivatization methods for commercially available carbohydrates (for example, Japanese Patent Laid-Open No. Hei. Can be synthesized by carrying out the method described in JP-A-8-245678.

  The sugar ester compound has a number average molecular weight of preferably 200 to 3500, more preferably 200 to 3000, and particularly preferably 250 to 2000.

Specific examples of the sugar ester compound that can be preferably used in the present invention are listed below, but the present invention is not limited to the following embodiments.
In the following structural formulae, R each independently represents an arbitrary substituent, and a plurality of R may be the same or different.

It is preferable to contain 2-30 mass% of said sugar ester compounds with respect to a cellulose acylate, It is more preferable to contain 5-20 mass%, It is especially preferable to contain 5-15 mass%.
In addition, when an additive having a negative intrinsic birefringence, which will be described later, is used in combination with the sugar ester compound, the additive amount (parts by mass) of the sugar ester compound with respect to the additive amount (parts by mass) of the additive having a negative intrinsic birefringence. Is preferably added 2 to 10 times (mass ratio), more preferably 3 to 8 times (mass ratio).
Moreover, when using together the polyester plasticizer mentioned later with the said sugar ester compound, the addition amount (mass part) of the said sugar ester compound with respect to the addition amount (mass part) of a polyester plasticizer is 2-10 times (mass). Ratio) is preferably added, more preferably 3 to 8 times (mass ratio).
In addition, the said sugar ester compound may be used independently, or may use 2 or more types together.

  In the cellulose ester film, various low-molecular and high-molecular additives (for example, deterioration inhibitors, UV inhibitors, retardation (optical anisotropy) modifiers, release accelerators, plasticizers) according to applications in each preparation step. Agents, infrared absorbers, matting agents, etc.), which may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing materials having a melting point of 20 ° C. or lower and 20 ° C. or higher, and similarly mixing of a deterioration preventing agent. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the cellulose ester solution (dope) preparation step, but may be added by adding an additive to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a cellulose-ester-type resin layer is formed from a multilayer, the kind and addition amount of the additive of each layer may differ.

(Retardation expression agent)
In order to express the retardation value, a compound having at least two aromatic rings can be used as a retardation enhancer.
The compound having at least two aromatic rings preferably exhibits optically positive uniaxiality when uniformly oriented.
The molecular weight of the compound having at least two or more aromatic rings is preferably 300 to 1200, more preferably 400 to 1000.
Stretching is effective for controlling optical characteristics, particularly Re, to a preferred value. To increase Re, it is necessary to increase the refractive index anisotropy in the film plane, and one method is to improve the main chain orientation of the polymer film by stretching. Further, by using a compound having a large refractive index anisotropy as an additive, the refractive index anisotropy of the film can be further increased. For example, the compound having two or more aromatic rings described above is improved in the orientation of the compound by transmitting the force of aligning the polymer main chains by stretching, and can easily be controlled to have desired optical characteristics.

Examples of the compound having at least two aromatic rings include triazine compounds described in JP-A No. 2003-344655, rod-like compounds described in JP-A No. 2002-363343, JP-A Nos. 2005-134848 and 2007-119737. Examples thereof include liquid crystal compounds described in the publication. More preferably, the triazine compound or the rod-like compound.
Two or more compounds having at least two aromatic rings can be used in combination.

  It is preferable that the support contains a compound represented by the following general formula (III) as a retardation developer. By including the compound represented by the following general formula (III), the expression of optical characteristics per unit film thickness is improved, which can contribute to the thinning.

R _{5 to} R ₇ each independently represent —OCH ₃ or —CH ₃ .

  The addition amount of the compound having at least two aromatic rings is preferably 0.05% or more and 10% or less, more preferably 0.5% or more and 8% or less, and more preferably 1% or more and 5% or less with respect to the cellulose ester. Further preferred.

(Peeling accelerator)
As additives for reducing the peeling resistance of cellulose ester films, many surfactants having a remarkable effect are found. As preferred release agents, phosphate ester surfactants, carboxylic acid or carboxylate surfactants, sulfonic acid or sulfonate surfactants, and sulfate ester surfactants are effective. A fluorine-based surfactant in which part of the hydrogen atoms bonded to the hydrocarbon chain of the surfactant is substituted with fluorine atoms is also effective.
The addition amount of the release agent is preferably 0.05 to 5% by mass, more preferably 0.1 to 2% by mass, and most preferably 0.1 to 0.5% by mass with respect to the cellulose ester.

[Acrylic layer]
The acrylic layer which the optical film of the present invention has will be described.
The acrylic layer is obtained by polymerizing an acrylic compound in which at least one hydroxyl group of the polyhydric alcohol compound is substituted with a (meth) acryloyl group and a polymerizable compound having a polar group and a polymerizable group.
Since sufficient adhesion can be obtained without subjecting the cellulose acylate film as the support to saponification treatment, the optical film production process does not require complicated steps, which is preferable from the viewpoint of productivity.

(Acrylic compound in which at least one hydroxyl group of a polyhydric alcohol compound is substituted with a (meth) acryloyl group and a polymerizable compound having a polar group and a polymerizable group)
The same compound may serve as the acrylic compound in which at least one hydroxyl group of the polyhydric alcohol compound is substituted with a (meth) acryloyl group and the polymerizable compound having the polar group and the polymerizable group. Alternatively, a mixture of each compound may be used.
The polar group of the polymerizable compound having a polar group and a polymerizable group is blended in order to introduce the hydrophilic property of the acrylic layer or the affinity with a specific compound.
In addition, depending on the type of polar group, affinity with cellulose as a support is improved, and improvement in adhesion between layers is also expected.
On the other hand, an acrylic compound obtained by substituting a hydroxyl group of a polyhydric alcohol compound with a (meth) acryloyl group is known as a polyfunctional acrylate, and since the polymer formed due to polyfunctionality forms a three-dimensional structure, a strong structure is obtained. .
A polyfunctional acrylic compound in which a plurality of substitutable sites of a polyhydric alcohol compound is substituted with a (meth) acryloyl group, and a part of the polyfunctional acrylic compound remains as a hydroxyl group, the remaining hydroxyl group functions as a polar group, and Since it has two or more, since it has the function of both the above-mentioned materials, the kind of material to be used can be reduced.
The acrylic resin having a polar group is preferably a resin containing a repeating unit derived from a compound containing a polar group and a (meth) acryloyl group.
A polar group indicates that the difference in electronegativity of two atoms bonded to each other is large. Specifically, a hydroxyl group, C═O, —COOH, —NH ₂ , —NO ₂ , —NH ₃ ⁺ , -CN and the like, and a hydroxyl group is preferable.
The acrylic resin having a polar group in the present invention may contain a repeating unit not having a polar group, or may contain a repeating unit other than a repeating unit derived from a compound containing a (meth) acryloyl group. Also good.

  As the acrylic compound in which at least one hydroxyl group of the polyhydric alcohol compound is substituted with a (meth) acryloyl group, three or more (meth) acryloyl per molecule are used from the viewpoint of improving adhesion to the support and film strength. A polyfunctional acrylic compound having a group is preferred.

(Polyfunctional acrylic compound having three or more (meth) acryloyl groups in one molecule)
As a compound having three or more functional groups in one molecule, a compound having a polymerizable functional group (polymerizable unsaturated double bond) such as a (meth) acryloyl group, a vinyl group, a styryl group, or an allyl group. Among them, a compound having a (meth) acryloyl group and —C (O) OCH═CH ₂ is preferable. Particularly preferred are polyfunctional acrylic compounds containing three or more (meth) acryloyl groups in one molecule described below.

  Among them, esters in which a plurality of polyhydric alcohol (meth) acryloyl groups are introduced are preferable. For example, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO modified trimethylolpropane tri (meth) acrylate, PO modified trimethylolpropane tri (meth) acrylate, EO Modified tri (meth) acrylate phosphate, trimethylolethane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa ( (Meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, urethane acrylate Polyester polyacrylate and caprolactone-modified tris (acryloyloxyethyl) isocyanurate.

  As the polyfunctional acrylic compound having three or more functional groups in one molecule, commercially available monomers can be used. For example, examples of the polyfunctional acrylate compounds having a (meth) acryloyl group include KAYARAD PET30, KAYARAD DPHA, DPCA-30, and DPCA-120 manufactured by Nippon Kayaku Co., Ltd. Examples of the urethane acrylate include U15HA manufactured by Shin-Nakamura Chemical Co., Ltd., U4HA, A-9300, and EB5129 manufactured by Daicel UCB.

(Polymerizable compound having polar group and polymerizable group)
The polymerizable compound having a polar group and a polymerizable group is preferably a compound having one or more polymerizable groups and one or more polar groups in a molecule at the same time in the molecular structure. A compound having a group and one or more polar groups simultaneously in the molecular structure is more preferable, and a compound having two or more polymerizable groups and two or more polar groups simultaneously in the molecular structure is most preferable.
Here, the polar group means that the difference in electronegativity of two atoms bonded to each other is large. Specifically, a hydroxyl group, C═O, —COOH, —NH ₂ , —NO ₂ , — NH ₃ ⁺ , —CN and the like can be mentioned, and a hydroxyl group is preferable.
The ratio of the compound having a polar group and a polymerizable group contained in the acrylic layer is preferably 30% by mass or more based on the total of the polyhydric alcohol compound.
The composition for forming an acrylic layer according to the present invention preferably contains a photopolymerization initiator.
As photopolymerization initiators, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, Examples include fluoroamine compounds, aromatic sulfoniums, lophine dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, and coumarins. Specific examples, preferred embodiments, commercially available products, and the like of the photopolymerization initiator are described in paragraphs [0133] to [0151] of JP-A-2009-098658, and can be suitably used in the present invention as well. it can.

  “Latest UV Curing Technology” {Technical Information Association, Inc.} (1991), p. 159, and “UV Curing System” written by Kiyomi Kato (published by the General Technology Center in 1989), p. Various examples are also described in 65-148 and are useful in the present invention.

  The content of the photopolymerization initiator in the composition for forming an acrylic layer according to the present invention is sufficiently high to polymerize the polymerizable compound contained in the composition for forming an acrylic layer, and the starting point does not increase too much. From the reason that it is set to a sufficiently small amount, 0.5 to 8% by mass is preferable and 1 to 5% by mass is more preferable with respect to the total solid content in the composition for forming an acrylic layer.

  The acrylic layer is a layer containing an acrylic resin having a polar group, and the acrylic resin is a layer obtained by crosslinking an acrylic monomer with light or heat, and the polar group is particularly preferably a hydroxyl group. Thereby, the liquid crystal compound can be effectively aligned in the retardation layer in which the alignment state of the liquid crystal material described later is fixed.

(Method for forming acrylic layer)
The acrylic layer can be formed by applying the acrylic layer-forming composition directly on the cellulose acylate film as a support or via another layer and drying the composition.
In the case where the material of the acrylic layer is an acrylic resin having a polar group, it is preferable to use a solvent having a solubility for cellulose acylate and a solvent having a swelling ability for cellulose acylate.
As the solvent capable of swelling cellulose acylate swells the cellulose ester film, a compound that forms an acrylic resin having a polar group penetrates the cellulose ester film. Moreover, a cellulose ester diffuses | diffuses to an intermediate | middle layer side because the solvent which has the solubility with respect to a cellulose acylate melt | dissolves a cellulose ester film. Thereby, even if it does not perform a saponification process to a cellulose acylate film, it is excellent in adhesiveness with an intermediate | middle layer.

[Solvents capable of dissolving and swelling in cellulose acylate]
The solvent having the ability to dissolve cellulose acylate was taken out by immersing a base film having a size of 24 mm × 36 mm (thickness 80 μm) in a 15 cc bottle containing the solvent at room temperature (25 ° C.) for 60 seconds. Later, when the soaked solution is analyzed by gel permeation chromatography (GPC), it means a solvent having a peak area of cellulose acylate of 400 mV / sec or more. Alternatively, a cellulose acylate film with a size of 24 mm × 36 mm (thickness 80 μm) is aged in a 15 cc bottle containing the solvent at room temperature (25 ° C.) for 24 hours, and the bottle is shaken as appropriate. What dissolves and loses its shape also means a solvent having the ability to dissolve cellulose acylate.
The solvent having swelling ability for cellulose acylate is a base film having a size of 24 mm × 36 mm (thickness 80 μm) placed vertically in a 15 cc bottle containing the solvent and immersed at 25 ° C. for 60 seconds. Observe while shaking the bottle as appropriate, meaning a solvent that can be bent or deformed (the film is observed as bent or deformed due to changes in the size of the swollen part. Changes such as bending or deformation in a solvent without swelling ability. Is not seen).

As the solvent having the ability to dissolve and swell the cellulose acylate, the solvents described in paragraph [0026] of JP-A-2008-112177 can be used.
For example, ethers having 3 to 12 carbon atoms such as dibutyl ether and tetrahydrofuran, carbons having 3 to 12 carbon atoms such as acetone, methyl ethyl ketone, diethyl ketone, cyclopentanone and cyclohexanone, carbon such as methyl acetate and ethyl acetate Solvents such as esters having a number of 3 to 12 and organic solvents having two or more types of functional groups can be used, and these can be used alone or in combination of two or more.
In addition, in order to control the effect of the solvent, a solvent having neither a dissolving ability nor a swelling ability can be used in combination with the cellulose acylate film.
As the solvent having neither dissolving ability nor swelling ability, the solvents described in paragraph [0027] of JP-A-2008-112177 can be used.
For example, methyl isobutyl ketone (MIBK), methanol, ethanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-propanol, 2-methyl-2-butanol, cyclohexanol, 2-octanone, 2 -Pentanone, 2-hexanone, 2-heptanone, 3-pentanone, 3-heptanone, 4-heptanone, isobutyl acetate.
The amount of the solvent having neither dissolving ability nor swelling ability is preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less with respect to the total solvent used.

The total solvent amount in the composition for forming an acrylic layer is such that the solid content in the composition is preferably in the range of 1 to 70% by mass, more preferably in the range of 20 to 70% by mass, still more preferably 40 to 70% by mass. % Is preferable, 45 to 65% by mass is even more preferable, 50 to 65% by mass is particularly preferable, and 55 to 65% by mass is most preferable.
The thickness of the acrylic layer is preferably 0.15 to 2.0 μm from the viewpoint of thinning.

[Retardation layer with fixed orientation of liquid crystal material]
The retardation layer which fixed the orientation state of the liquid crystal material which the optical film of this invention has is demonstrated.
In the present invention, it is preferable that the acrylic layer and the retardation layer are adjacent to each other from the viewpoint of adhesion and thinning.
The retardation layer is obtained by polymerizing and curing a polymerizable liquid crystal compound, and the polymerizable liquid crystal compound is a polymerizable group for fixing the alignment state at the end of a rigid group (referred to as a mesogen group) having a rigid portion. Can be used.
The shape is roughly classified into a rod shape and a disc shape (discotic), and optical anisotropy resulting from the shape can be expressed.
In the present invention, a rod-like liquid crystal compound is preferable, and the rod-like liquid crystal compound is preferably a benzoic acid ester compound.
The polymerizable group for fixing the orientation preferably has an ethylenically unsaturated bond, and more preferably a rod-like liquid crystal compound having an ethylenically unsaturated bond at both ends.
Further, the rod-like liquid crystal compound can be preferably used because it is homeotropically aligned and does not require alignment in the in-plane direction of the optical film and can be easily used. Also, other alignment states such as homogeneous alignment, hybrid alignment, and cholesteric alignment can be used by using additives such as rubbing and chiral agents.

  The layer in which the homeotropic alignment of the rod-like liquid crystal compound is fixed can function as a positive C-plate.

  The type of the liquid crystal compound used for forming the retardation layer in which the alignment state of the liquid crystal material included in the optical film of the present invention is fixed is not particularly limited. For example, a low-molecular liquid crystalline compound is formed in a nematic alignment in a liquid crystal state, and then a retardation layer obtained by fixing by photocrosslinking or thermal crosslinking, or a high molecular liquid crystalline compound is formed in a nematic alignment in a liquid crystal state and then cooled. Thus, a retardation layer obtained by fixing the orientation can also be used. In the present invention, the retardation layer in which the alignment state of the liquid crystal material is fixed is a layer formed by fixing the liquid crystalline compound by polymerization or the like, and it is no longer necessary to exhibit liquid crystallinity after forming the layer. . The polymerizable liquid crystal compound may be a polyfunctional polymerizable liquid crystal or a monofunctional polymerizable liquid crystal compound. The liquid crystal compound may be a discotic liquid crystal compound or a rod-like liquid crystal compound.

  The retardation layer in which the alignment state of the liquid crystal material is fixed is a coating liquid containing a liquid crystal compound such as a rod-like liquid crystal compound or a discotic liquid crystal compound, and, if desired, a polymerization initiator, an alignment controller, and other additives described later. Can be formed by coating on the acrylic layer.

[Discotic liquid crystal compound]
In the present invention, it is preferable to use a discotic liquid crystal compound for forming the retardation layer in which the alignment state of the liquid crystal material included in the optical film is fixed. Discotic liquid crystal compounds are disclosed in various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by The Chemical Society of Japan, Quarterly Chemical Review, No. 22, Liquid Crystal). Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J. Chem. Am. Chem. Soc., Vol. 116, page 2655 (1994)). The polymerization of discotic liquid crystal compounds is described in JP-A-8-27284.

  Specific examples of the discotic liquid crystal compound that can be preferably used in the present invention include compounds described in JP-A-2009-97002 [0038] to [0069]. Further, examples of the discotic liquid crystalline compound having a small wavelength dispersion, which is a triphenylene compound, include compounds described in paragraphs [0062] to [0067] of JP-A-2007-108732.

[Bar-shaped liquid crystal compound]
In the present invention, a rod-like liquid crystal compound is preferable. Examples of the rod-like liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used. It is more preferable to fix the alignment of the rod-like liquid crystal compound by polymerization. As the liquid crystalline compound, those having a partial structure capable of causing polymerization or crosslinking reaction by actinic rays, electron beams, heat, or the like are suitably used. The number of the partial structures is preferably 1 to 6, more preferably 1 to 3. Examples of the polymerizable rod-like liquid crystal compound include Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, International Publication WO95 / 22586. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, No. 7-110469. 11-80081 and JP-A-2001-328773, etc. can be used.

  From the viewpoint of optical development, the retardation layer in which the alignment state of the liquid crystal material is fixed is selected from the group consisting of the compound represented by the following general formula (IA) and the compound represented by the following general formula (IIA). It is preferable to contain at least one compound.

R _{1 to} R ₄ are each independently — (CH ₂ ) _n —OOC—CH═CH ₂ , and n represents an integer of 2 to 5. X and Y each independently represent a hydrogen atom or a methyl group.

From the viewpoint of inhibiting crystal precipitation, in the general formula (IA) or (IIA), X and Y preferably represent a methyl group. From the viewpoint of exhibiting properties as a liquid crystal, n is preferably an integer of 1 to 5.
Further, from the viewpoint of suppressing crystallization and precipitation, the retardation layer in which the alignment state of the liquid crystal material is fixed is any one of the compound represented by the general formula (IA) and the compound represented by the general formula (IIA). The compound is also preferably contained in an amount of 3% by mass or more, more preferably 5% by mass or more and 20% by mass or less, based on the total solid content of the liquid crystal composition layer.

(Onium compound represented by general formula (I))
The retardation layer of the optical film of the present invention preferably contains an onium compound represented by the following general formula (I). The onium compound acts as a vertical alignment agent that promotes vertical alignment at the alignment film interface of the liquid crystal compound, and also contributes to improvement in adhesion at the interface between the retardation layer and the acrylic layer. The retardation layer may contain an air interface side orientation control agent (for example, a copolymer containing a repeating unit having a fluoroaliphatic group) for controlling the orientation on the air interface side, if necessary.
The onium compound represented by the general formula (I) is added for the purpose of controlling the alignment of the liquid crystal compound at the acrylic layer interface, and has the effect of increasing the tilt angle in the vicinity of the acrylic layer interface of the molecules of the liquid crystal compound.

In general formula (I), ring A represents a quaternary ammonium ion composed of a nitrogen-containing heterocycle, X represents an anion; L ¹ represents a divalent linking group; L ² represents a single bond or a divalent group. Y ¹ represents a divalent linking group having a 5- or 6-membered ring as a partial structure; Z represents a divalent linking group having 2 to 20 alkylene groups as a partial structure; P ¹ and P ² independently represents a monovalent substituent having a polymerizable ethylenically unsaturated group.

  Ring A represents a quaternary ammonium ion composed of a nitrogen-containing heterocyclic ring. Examples of ring A include pyridine ring, picoline ring, 2,2′-bipyridyl ring, 4,4′-bipyridyl ring, 1,10-phenanthroline ring, quinoline ring, oxazole ring, thiazole ring, imidazole ring, pyrazine ring , Triazole ring, tetrazole ring and the like, preferably quaternary imidazolium ion and quaternary pyridinium ion.

  X represents an anion. Examples of X include a halogen anion (for example, fluorine ion, chlorine ion, bromine ion, iodine ion, etc.), sulfonate ion (for example, methanesulfonate ion, trifluoromethanesulfonate ion, methylsulfate ion, vinylsulfonate ion) , Allyl sulfonate ion, p-toluene sulfonate ion, p-chlorobenzene sulfonate ion, p-vinylbenzene sulfonate ion, 1,3-benzene disulfonate ion, 1,5-naphthalene disulfonate ion, 2,6- Naphthalenedisulfonate ion), sulfate ion, carbonate ion, nitrate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion, picrate ion, acetate ion, benzoate ion, p-vinylbenzoate ion, formate ion The trifle B acetate ion, phosphoric acid ion (e.g., hexafluorophosphate ion), such as a hydroxide ion. Preferred are halogen anions, sulfonate ions, and hydroxide ions. In particular, chlorine ion, bromine ion, iodine ion, methanesulfonic acid ion, vinylsulfonic acid ion, p-toluenesulfonic acid ion, and p-vinylbenzenesulfonic acid ion are preferable.

L ¹ represents a divalent linking group. Examples of L ¹ include an alkylene group, —O—, —S—, —CO—, —SO ₂ —, —NRa— (where Ra is an alkyl group having 1 to 5 carbon atoms or a hydrogen atom. ), A divalent linking group having 1 to 20 carbon atoms, which is a combination with an alkenylene group, an alkynylene group or an arylene group. L ¹ is preferably -AL-, -O-AL-, -CO-O-AL-, or -O-CO-AL- having 1 to 10 carbon atoms, and -AL having 1 to 10 carbon atoms. -And -O-AL- are more preferable, and -AL- and -O-AL- having 1 to 5 carbon atoms are most preferable. AL represents an alkylene group.

L ² represents a single bond or a divalent linking group. Examples of L ² include an alkylene group, —O—, —S—, —CO—, —SO ₂ —, —NRa— (where Ra is an alkyl group having 1 to 5 carbon atoms or a hydrogen atom. ), A divalent linking group having 1 to 10 carbon atoms consisting of a combination with an alkenylene group, an alkynylene group or an arylene group, a single bond, —O—, —O—CO—, —CO—O—, —O -AL-O-, -O-AL-O-CO-, -O-AL-CO-O-, -CO-O-AL-O-, -CO-O-AL-O-CO-, -CO -O-AL-CO-O-, -O-CO-AL-O-, -O-CO-AL-O-CO-, -O-CO-AL-CO-O-, and the like can be given. AL represents an alkylene group. L ² is preferably a single bond, -AL- having 1 to 10 carbon atoms, -O-AL-, or -NRa-AL-O-, a single bond, -AL- having 1 to 5 carbon atoms, —O—AL— and —NRa—AL—O— are more preferable, and —O—AL— and —NRa—AL—O— having a single bond and 1 to 5 carbon atoms are most preferable.

Y ¹ represents a divalent linking group having a 5- or 6-membered ring as a partial structure. Examples of Y ¹ include a cyclohexyl ring, an aromatic ring or a heterocyclic ring. Examples of the aromatic ring include a benzene ring, an indene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, a biphenyl ring, and a pyrene ring, and a benzene ring, a biphenyl ring, and a naphthalene ring are particularly preferable. The hetero atom constituting the hetero ring is preferably a nitrogen atom, an oxygen atom or a sulfur atom. For example, a furan ring, thiophene ring, pyrrole ring, pyrroline ring, pyrrolidine ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole Ring, imidazole ring, imidazoline ring, imidazolidine ring, pyrazole ring, pyrazoline ring, pyrazolidine ring, triazole ring, furazane ring, tetrazole ring, pyran ring, dioxane ring, dithiane ring, thiine ring, pyridine ring, piperidine ring, oxazine ring Morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring and triazine ring. The heterocycle is preferably a 6-membered ring. The divalent linking group having a 5- or 6-membered ring represented by Y ¹ as a partial structure may further have a substituent.

  Examples of the substituent include a halogen atom, a cyano group, an alkyl group having 1 to 12 carbon atoms (more preferably 1 to 10, more preferably 1 to 5), and 2 to 12 carbon atoms (more preferably). An alkenyl group having 2 to 10 and more preferably 2 to 5), an alkoxy group having 1 to 12 carbon atoms (more preferably 1 to 10, more preferably 1 to 5), and the like can be mentioned. The alkyl group and the alkoxy group have an acyl group having 2 to 12 carbon atoms (more preferably 2 to 10 and more preferably 2 to 5) or 2 to 12 carbon atoms (more preferably 2 to 10 and more preferably). May be substituted with an acyloxy group of 2-5). The acyl group is represented by —CO—R, the acyloxy group is represented by —O—CO—R, and R is an aliphatic group (alkyl group, substituted alkyl group, alkenyl group, substituted alkenyl group, alkynyl group, substituted alkynyl group) or aromatic. Group (aryl group, substituted aryl group). R is preferably an aliphatic group, and more preferably an alkyl group or an alkenyl group.

The divalent linking group represented by Y ¹ is preferably a divalent linking group having two or more 5- or 6-membered rings, and preferably has a structure in which two or more rings are connected by a linking group. More preferred. Examples of linking groups include linking groups represented by L ¹ and L ^2, and —C≡C—, —CH═CH—, —CH═N—, —N═CH—, —N═N— and the like. Can be mentioned.

Z represents a divalent linking group having a combination of —O—, —S—, —CO—, and —SO ₂ — with a C 2-20 alkylene group as a partial structure, and an alkylene group May have a substituent. Examples of the divalent linking group include an alkyleneoxy group and a polyalkyleneoxy group. The number of carbon atoms of the alkylene group represented by Z is more preferably 2 to 16, more preferably 2 to 12, and particularly preferably 2 to 8.

P ¹ and P ² each independently represent a monovalent substituent having a polymerizable ethylenically unsaturated group. Examples of the monovalent substituent having the polymerizable ethylenically unsaturated group include the following formulas (M-1) to (M-8). That is, the monovalent substituent having a polymerizable ethylenically unsaturated group may be a substituent consisting only of an ethenyl group as in (M-8).

In formulas (M-3) and (M-4), R represents a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group. Among the above formulas (M-1) to (M-8), (M-1), (M-2) and (M-8) are preferable, and (M-1) or (M-8) is more preferable. . In particular, (M-1) is preferable as P ¹ . P ² is preferably (M-1) or (M-8), and in the compound in which ring A is a quaternary imidazolium ion, P ² is (M-8) or (M-1). And in compounds where ring A is a quaternary pyridinium ion, P ² is preferably (M-1).

  The onium compounds represented by the general formula (I) include onium compounds represented by the following general formulas (I-1) and (I-2).

The definition of each symbol of general formula (I-1) and (I-2) is synonymous with each in general formula (I); L < ³ > and L < ⁴ > represent a bivalent coupling group each independently; Y ² and Y ³ are each independently a 6-membered ring optionally having a substituent; m represents 1 or 2, and when m is 2, two L ⁴ and two Y ³ are They may be the same or different; p represents an integer of 1 to 10.

L ³ represents a divalent linking group, and examples of L ³ include a single bond, —O—, —O—CO—, —CO—O—, —O—AL—O—, —O—AL. -O-CO-, -O-AL-CO-O-, -CO-O-AL-O-, -CO-O-AL-O-CO-, -CO-O-AL-CO-O-, -O-CO-AL-O-, -O-CO-AL-O-CO-, and -O-CO-AL-CO-O-. Note that AL represents an alkylene group having 1 to 10 carbon atoms. L ³ represents a single bond, —O—, —O—AL—O—, —O—AL—O—CO—, —O—AL—CO—O—, —CO—O—AL—O—, — CO-O-AL-O-CO-, -CO-O-AL-CO-O-, -O-CO-AL-O-, -O-CO-AL-O-CO-, -O-CO- AL-CO-O- is preferable, a single bond or -O- is more preferable, and -O- is most preferable.

L ⁴ represents a divalent linking group, and examples of L ⁴ include a single bond, —O—, —O—CO—, —CO—O—, —C≡C—, —CH═CH—, -CH = N-, -N = CH-, -N = N-, -NH-CO-, -CO-NH-. L ⁴ is preferably a single bond, —O—CO—, —CO—O—, —C≡C—, —NH—CO—, —CO—NH—, and preferably a single bond, —O—CO—, —CO. —O— is more preferable, and —O—CO— and —CO—O— are most preferable.

Y ² and Y ³ each independently represent a 6-membered ring optionally having a substituent, and the 6-membered ring includes an aliphatic ring, an aromatic ring (benzene ring) and a heterocyclic ring. Examples of the aliphatic 6-membered ring include a cyclohexane ring, a cyclohexene ring, and a cyclohexadiene ring. Examples of the aromatic ring include a benzene ring, an indene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, a biphenyl ring, and a pyrene ring. Examples of 6-membered heterocycles include pyran ring, dioxane ring, dithiane ring, thiine ring, pyridine ring, piperidine ring, oxazine ring, morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring, triazine ring Etc. Further, another 6-membered ring or a 5-membered ring may be condensed with the 6-membered ring. Y ² and Y ³ are preferably a cyclohexane ring, a pyridine ring, a pyrimidine ring or a benzene ring, more preferably a pyrimidine ring or a benzene ring, and most preferably a benzene ring.

Examples of the substituent include a halogen atom, a cyano group, an alkyl group having 1 to 12 carbon atoms (more preferably 1 to 10, more preferably 1 to 5), an alkoxy group having 1 to 12 carbon atoms, and the like. Is mentioned. The alkyl group and the alkoxy group may be substituted with an acyl group having 2 to 12 carbon atoms or an acyloxy group having 2 to 12 carbon atoms. The acyl group is represented by —CO—R, the acyloxy group is represented by —O—CO—R, and R is an aliphatic group (alkyl group, substituted alkyl group, alkenyl group, substituted alkenyl group, alkynyl group, substituted alkynyl group) or aromatic. Group (aryl group, substituted aryl group). R is preferably an aliphatic group, and more preferably an alkyl group or an alkenyl group.
In formulas (I-1) and (I-2), at least one Y ³ is preferably a substituted benzene ring, preferably a benzene ring having one or more halogen groups, alkyl groups or alkoxy groups. Is more preferable, and a benzene ring having two or more alkyl groups or alkenyl groups is more preferable.

m represents an integer of 1 or 2, and when m is 2, two L ⁴ and two Y ³ may be different.

C _p H _2p represents a chain alkylene group which may have a branched structure. C _p H _2p is preferably a linear alkylene group (— (CH ₂ ) _p —).

  p represents an integer of 1 to 10, more preferably 1 to 5, and most preferably 1 to 2.

  The onium compounds represented by the general formula (I) include onium compounds represented by the following general formulas (I-3) and (I-4).

  The definition of each symbol of general formula (I-3) and (I-4) is synonymous with each in general formula (I-1) or (I-2); R 'represents a substituent; b represents an integer of 1 to 4.

Examples of R ′ are the same as the examples of the substituent of the 6-membered ring represented by Y ² and Y ³ in general formula (I-1) or (I-2), and the preferred ranges are also the same. . That is, R ′ is preferably a halogen group, an alkyl group or an alkoxy group.
b represents an integer of 1 to 4, more preferably 1 to 3, and still more preferably 2 to 3.

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

The onium compound of the general formula (I) can be generally synthesized by alkylating a nitrogen-containing heterocycle (Menstokin reaction).
The composition for forming a retardation layer according to the present invention preferably contains a photopolymerization initiator.

[Air interface side vertical alignment agent]
It is preferable that the retardation layer contains a fluorine atom.
As the air interface side vertical alignment agent in the present invention, the following fluorine-based polymer (including formula (II) as a partial structure) or a fluorine-containing compound represented by general formula (III) is preferably used.

  First, the fluorine-based polymer (including formula (II) as a partial structure) will be described. As the air interface side vertical alignment agent of the present invention, the fluoropolymer is a copolymer containing a repeating unit derived from a fluoroaliphatic group-containing monomer and a repeating unit represented by the following formula (II). Is preferred.

In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituent,
L represents a divalent linking group selected from the following linking group group or a divalent linking group formed by combining two or more selected from the following linking group group;
(Linked group group)
[Single bond, —O—, —CO—, —NR ⁴ — (R ⁴ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group), —S—, —SO ₂ —, —P (═O ) (OR ₅ ) — (R ₅ represents an alkyl group, an aryl group, or an aralkyl group), an alkylene group, and an arylene group]
Q represents a carboxyl group (—COOH) or a salt thereof, a sulfo group (—SO ₃ H) or a salt thereof, or phosphonoxy {—OP (═O) (OH) ₂ } or a salt thereof.

The fluoropolymer that can be used in the present invention includes a fluoroaliphatic group, a carboxyl group (—COOH), a sulfo group (—SO ₃ H), a phosphonoxy group {—OP (═O) (OH) ₂ }, and their It contains one or more hydrophilic groups selected from the group consisting of salts. The types of polymers are described in “Revised Chemistry of Polymer Synthesis” (Takayuki Otsu, published by Kagaku Dojin Co., 1968), pages 1-4, for example, polyolefins, polyesters, polyamides, polyimides. , Polyurethanes, polycarbonates, polysulfones, polycarbonates, polyethers, polyacetals, polyketones, polyphenylene oxides, polyphenylene sulfides, polyarylates, PTFEs, polyvinylidene fluorides, cellulose derivatives, etc. It is done. The fluoropolymer is preferably a polyolefin.

  The fluorine-based polymer is a polymer having a fluoroaliphatic group in the side chain. The fluoroaliphatic group preferably has 1 to 12 carbon atoms, and more preferably 6 to 10 carbon atoms. The aliphatic group may be linear or cyclic, and when it is linear, it may be linear or branched. Of these, a linear fluoroaliphatic group having 6 to 10 carbon atoms is preferable. The degree of substitution with fluorine atoms is not particularly limited, but 50% or more of hydrogen atoms in the aliphatic group are preferably substituted with fluorine atoms, and more preferably 60% or more are substituted. The fluoroaliphatic group is contained in a side chain bonded to the polymer main chain via an ester bond, an amide bond, an imide bond, a urethane bond, a urea bond, an ether bond, a thioether bond, an aromatic ring, or the like.

  Specific examples of the fluoroaliphatic group-containing copolymer preferably used in the present invention as a fluoropolymer include the compounds described in paragraphs [0110] to [0114] of JP-A-2006-113500. Is not limited by these specific examples.

  The fluorine-based polymer used in the present invention preferably has a mass average molecular weight of 1,000,000 or less, more preferably 500,000 or less, and still more preferably 100,000 or less. The mass average molecular weight can be measured as a value in terms of polystyrene (PS) using gel permeation chromatography (GPC).

  The fluorine-based polymer of the present invention preferably has a polymerizable group as a substituent in order to fix the alignment state of the liquid crystal compound.

  The preferred range of the content of the fluoropolymer in the composition varies depending on its use, but when used for forming a retardation layer in which the alignment state of the liquid crystal material is fixed, the composition (solvent in the case of a coating liquid) Is preferably 0.005 to 8% by mass, more preferably 0.01 to 5% by mass, and still more preferably 0.05 to 3% by mass. If the addition amount of the fluorine-based polymer is less than 0.005% by mass, the effect is insufficient, and if it exceeds 8% by mass, the coating film cannot be sufficiently dried, or the performance as an optical film (for example, letter Adversely affects the uniformity of the foundation.

A fluorine-containing compound represented by the following general formula (III).
Formula (III)
(R ⁰ ) _m -L ^0- (W) _n
In the formula, R ⁰ represents an alkyl group, an alkyl group having a CF ₃ group at the terminal, or an alkyl group having a CF ₂ H group at the terminal, and m represents an integer of 1 or more. A plurality of R ⁰ may be the same or different, but at least one represents an alkyl group having a CF ₃ group or a CF ₂ H group at the terminal. L ⁰ represents a (m + n) -valent linking group, W represents a carboxyl group (—COOH) or a salt thereof, a sulfo group (—SO ₃ H) or a salt thereof, or phosphonoxy {—OP (═O) (OH) ₂ } Or a salt thereof, and n represents an integer of 1 or more.

  Specific examples of the fluorine-containing compound represented by the general formula (III) that can be used in the present invention include compounds described in paragraphs [0136] to [0140] of JP-A-2006-113500. The invention is not limited by these specific examples.

  In addition, the fluorine-containing compound of the present invention preferably has a polymerizable group as a substituent in order to fix the alignment state of the liquid crystalline compound.

  The preferred range of the content of the fluorine-containing compound in the composition varies depending on its use, but when used for forming the retardation layer, in the composition (a composition excluding the solvent in the case of a coating solution), The amount is preferably 0.005 to 8% by mass, more preferably 0.01 to 5% by mass, and still more preferably 0.05 to 3% by mass.

[Polymerization initiator]
The aligned (preferably vertically aligned) liquid crystal compound is fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction of a polymerizable group introduced into the liquid crystal compound. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Description), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,212,970).

The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution. It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules. The irradiation energy ^is preferably ^{20mJ / cm 2 ~50J / cm 2} , further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions or at a low oxygen concentration of 0.1% or less. The thickness of optical anisotropy containing the liquid crystalline compound is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 1 to 5 μm.

  The retardation layer preferably contains any element of boron atom, bromine atom, nitrogen atom and sulfur atom, and any element of boron atom, bromine atom, nitrogen atom and sulfur atom is contained in the acrylic layer. It is more preferable that they are unevenly distributed on the near side.

(Thickness of retardation layer with fixed orientation of liquid crystal material)
The thickness of the retardation layer in which the alignment state of the liquid crystal material is fixed is preferably 0.5 to 2.0 μm, and preferably 1.0 to 2.0 μm from the viewpoint that it can contribute to thinning and hardly cause curling of the film. Is more preferable.

[Phase difference film]
The optical film of the present invention can be used as a laminated retardation film having at least a retardation layer in which the alignment state of the support, the acrylic layer, and the liquid crystal material is fixed.

(Optical characteristics of retardation film)
The optical characteristics of the optical film of the present invention satisfy the following formulas (1), (2), and (3).
80 ≦ Re ≦ 150 Formula (1)
−100 ≦ Rth ≦ 10 Formula (2)
0.05 ≦ | Rth / Re | ≦ 1.0 Formula (3)
Here, Re and Rth are an in-plane retardation value and a retardation value in the thickness direction, respectively, measured with light having a wavelength of 550 nm at 25 ° C. and 60% RH.

(Optical film thickness)
The film thickness of the optical film is preferably 20 to 55 μm, more preferably 20 to 50 μm, from the viewpoint that it can cope with the recent thinning of the film, including the acrylic layer and the retardation layer.

  The retardation film preferably has a tear strength of 1.5 g to 6.0 g · cm / cm from the viewpoint of making the film having no problem in handling and punching.

  The retardation film preferably has a coefficient of dynamic friction on both surfaces of 0.6 or less. Thereby, slipperiness is given to a film and it becomes hard to squeak. The dynamic friction coefficients of both surfaces can be controlled by the amount of additive added.

(Optical film manufacturing method)
The method for producing an optical film of the present invention comprises a polymerization of an acrylic compound in which at least one hydroxyl group of a polyhydric alcohol compound is substituted with a (meth) acryloyl group and a polar group and a polymerizable group on a cellulose acylate support. After applying an acrylic layer containing a functional compound and curing the film by heat or ultraviolet irradiation, the polymerizable composition for the retardation layer is applied and oriented on the acrylic layer, and then aligned by heat or ultraviolet irradiation. A step of immobilizing.
Specifically, the optical film of the present invention can be formed by the following method, but is not limited to this method.
First, a cellulose acylate film as a support is produced.
Next, an acrylic layer forming composition is prepared, and the composition is applied to the support by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, a die coating method, or the like. Apply to, heat and dry. A micro gravure coating method, a wire bar coating method, and a die coating method (see US Pat. No. 2,681,294 and JP-A-2006-122889) are more preferable, and a die coating method is particularly preferable.
After the coating, drying and irradiation with light are cured to form an acrylic layer.
In order to further improve the adhesion between the obtained acrylic layer and the retardation layer, a known surface treatment such as corona treatment or plasma treatment may be performed.
Subsequently, a polymerizable composition for the retardation layer is prepared, applied on the acrylic layer, and the alignment state of the liquid crystal material is fixed by a polymerization reaction to form a retardation layer.
In this way, the optical film of the present invention is obtained. Further, other layers can be provided as necessary. In the method for producing an optical film of the present invention, a plurality of layers may be applied simultaneously or sequentially.

[Protective film for polarizing plate]
When the optical film is used as a surface protective film for a polarizing film (protective film for polarizing plate), the surface of the support, that is, the surface to be bonded to the polarizing film is hydrophilized, and saponification treatment is performed, so that polyvinyl alcohol is used. Adhesiveness with the polarizing film as a main component can be improved.

[Polarizer]
The polarizing plate of the present invention is a polarizing plate having a polarizing film and two protective films protecting both surfaces of the polarizing film, and at least one of the protective films is the optical film of the present invention.
One of the two protective films is preferably the optical film of the present invention, and the other is preferably a film made of an acrylic resin.
Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine-based polarizing film and the dye-based polarizing film can be generally produced using a polyvinyl alcohol film.

  A structure in which the cellulose acylate film of the optical film is adhered to the polarizing film through an adhesive layer made of polyvinyl alcohol, if necessary, and a protective film is also provided on the other side of the polarizing film. The surface of the other protective film opposite to the polarizing film may have an adhesive layer.

  The total film thickness of the polarizing plate (total film thickness of retardation film, polarizing film and protective film) is preferably 80 to 120 μm.

[Liquid Crystal Display]
The liquid crystal display device of the present invention has the optical film or polarizing plate of the present invention.
The optical film of the present invention can be used in any driving mode depending on the design of the layer structure, but the structure of the above-mentioned laminate can be advantageously used particularly for a liquid crystal display device in a transverse electric field mode such as an IPS mode.

A liquid crystal cell having two cell substrates and a liquid crystal layer sandwiched between them and aligned in parallel with the substrate in the vicinity of the cell substrate when no voltage is applied; A pair of arranged polarizing plates, a first retardation plate arranged between one polarizing plate and the cell substrate, and a second retardation plate arranged between the other polarizing plate and the cell substrate The slow retardation axis of the first retardation plate is arranged so as to be orthogonal to the major axis of the liquid crystal molecules in the vicinity of the inside of the cell substrate adjacent to the first retardation plate when no voltage is applied. In the liquid crystal display device operating in the transverse electric field mode, it is preferable that either the first retardation film or the second retardation film is the optical film of the present invention.
Further, another preferred embodiment of the liquid crystal display device of the present invention is as follows:
A first substrate on which unit pixels are arranged; a second substrate facing the first substrate; a liquid crystal layer formed between the first substrate and the second substrate and arranged in a first direction; A first polarizing plate formed outside the first substrate and having a polarization transmission axis parallel to the first direction, and a first polarizing plate formed outside the second substrate and having a polarization transmission axis perpendicular to the first direction. The first polarizing plate includes a polyvinyl alcohol film having a polarizing function, and a triacetyl cellulose film or an acrylic film on the inner and outer surfaces of the polyvinyl alcohol film, and the second polarizing plate. The polarizing plate is a polyvinyl alcohol film having a polarizing function, and a triacetyl cellulose film or an acrylic film on one surface of the polyvinyl alcohol film. , Comprising a laminated retardation film formed on the other surface of the polyvinyl alcohol film, the laminated retardation film is a liquid crystal display device is an optical film of the present invention.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

1. Production of Support (1) Production of Cellulose Acylate Film Cellulose acylate films were produced by the following methods.

(1) -1 Preparation of Dope Preparation Cellulose Acylate Solution:
The main agent, additive and solvent described in the following table are put into a mixing tank, stirred to dissolve each component, further heated to 90 ° C. for about 10 minutes, then filtered with an average pore size of 34 μm and baked with an average pore size of 10 μm. It filtered with the metal filter.
――――――――――――――――――――――――――――――――――
Support No. # 1 Cellulose Acylate Solution ――――――――――――――――――――――――――――――――――
Triacetylcellulose listed in Table 6 Total 100.0 parts by mass Additive 1 listed in Table 6 (Amounts listed in Table 6 Unit: parts by mass)
Additives 2 listed in Table 6 (Amounts listed in Table 6 Unit: parts by mass)
Methylene chloride Mass parts methanol with the mixing ratio shown in Table 6 Mass parts with the mixing ratio shown in Table 6 ――――――――――――――――――――――――― ―――――――――

Preparation of matting agent dispersion:
Next, the following components including each cellulose acylate solution prepared by the above method were charged into a disperser to prepare a mat agent dispersion.
―――――――――――――――――――――――――――――――――――
Matting agent dispersion ―――――――――――――――――――――――――――――――――――
-Matting agent (Aerosil R972) 0.2 parts by mass-Methylene chloride 72.4 parts by mass-Methanol 10.8 parts by mass-Each cellulose acylate solution 10.3 parts by mass ------- ―――――――――――――――――――――――

  100 parts by mass of each cellulose acylate solution and the above matting agent dispersion were mixed in an amount such that the inorganic fine particles were 0.02 parts by mass with respect to cellulose acylate to prepare a dope for film formation.

(1) -2 Casting The above-mentioned dope was cast using a band casting machine. The band was made of SUS.

(1) -3 Drying After the web (film) obtained by casting was peeled from the band, the pass roll was conveyed and dried at a drying temperature of 120 ° C. for 20 minutes. In addition, the drying temperature here means the film surface temperature of a film.

(1) -4 Stretching The obtained web (film) is peeled from the band, sandwiched between clips, and in the direction of film transport (MD) using a tenter at the stretching temperature and stretch ratio shown in the table under the conditions of fixed-end uniaxial stretching. ) In a direction (TD) orthogonal to the above.
The stretch ratio and stretch temperature are described in the following table. In addition,-means contraction.
(2) Production of cyclic olefin film ZF14 manufactured by Nippon Zeon Co., Ltd. was subjected to free width uniaxial stretching at a temperature of 140 ° C. and a stretching speed of 30 mm / min, and stretched 1.5 times.

(3) Manufacturing conditions and characteristics of each film The manufacturing conditions and characteristics of the cellulose acylate films prepared in Table 6 below are shown.
In addition, the addition amount of each additive was represented by the mass part with respect to 100 mass parts of main agents in the table | surface. The composition ratio of the solvent 1 and the solvent 2 is described in the table as a mass ratio. Further, the solid content concentration (unit mass%) of the cellulose acylate solution is described in the column of “Concentration” in the table.

The compounds used are shown below.
TPP: Triphenyl phosphate (plasticizer)
BDP: Biphenyl diphenyl phosphate (plasticizer)

Compound L1:

2. Formation of (Hydrophilic) Acrylic Layer The contents and solvent described in the following table were charged into a mixing tank, stirred, and filtered through a polypropylene filter having a pore size of 0.4 μm to prepare an acrylic layer forming composition.
4% by mass of a photopolymerization initiator (Irgacure 127, manufactured by BASF) was added to the solid content of the acrylic layer forming composition.
In addition, the composition ratio of the contents and the solvent is shown in the table as a mass ratio. Moreover, the solid content concentration (unit mass%) of the composition for forming an acrylic layer is described in the column of “Concentration” in the table.
In Table 7, “Material 2 content ratio” is a ratio (mass%) to the total of materials 1 and 2.

The composition for acrylic layer formation was apply | coated on the corresponding support body produced by "1. Production of a support body" using the gravure coater. After drying at 100 ° C., an irradiance of 400 mW / cm using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) of 160 W / cm while purging with nitrogen so that the oxygen concentration becomes 1.0 vol% or less. ² , the coating layer was cured by irradiating ultraviolet rays with an irradiation amount of 150 mJ / cm ² to form an acrylic layer shown in the following table.
The film thickness of the obtained acrylic layer is shown in Table 7. In the following table, IPA represents isopropyl alcohol.

  The compounds used are shown below.

  A1: KAYARAD PET30: Nippon Kayaku Co., Ltd., a mixture of compounds having the following structure. The weight average molecular weight is 298, and the number of functional groups in one molecule is 3.4 (average).

  A2: Urethane monomer: Compound having the following structure. The weight average molecular weight is 596, and the number of functional groups in one molecule is 4.

  A3: Compound having the following structure

  A4: Compound having the following structure

  B1: Blemmer GLM: NOF Corporation, a compound having the following structure.

  B2: Glycerol 1,3-diglycerolate diacrylate: manufactured by Aldrich, a compound having the following structure.

  B3: Allyl α-D-galactopyranoside: a compound having the following structure manufactured by Aldrich.

  B4: Compound having the following structure.

3. Formation of Retardation Layer A composition for retardation layer having the following composition was applied at a coating amount of 4 ml / m ² using a bar coater. The liquid crystal compound was aligned by heating for 120 seconds at the aging temperature shown in the following table. Thereafter, the temperature is maintained, and an ultraviolet ray irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) is irradiated with ultraviolet rays having an illuminance of 600 mW / cm ² for 4 seconds to advance the crosslinking reaction, thereby producing a liquid crystal compound. Was fixed in that orientation. Then, it stood to cool to room temperature and obtained the optical film.

────────────────────────────────────
Composition for retardation layer ────────────────────────────────────
Liquid crystal compounds shown in Table 8 below (total amount in the case of a mixture of liquid crystal compounds 1 and 2)
100.0 parts by mass

Alignment agents shown in Table 8 below Mass parts (phr) shown in Table 8 below
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 3.0 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1.0 part by mass Methyl ethyl ketone (MEK) Part by mass Cyclohexanone (anone) Part by mass with the mixing ratio shown in Table 8 ──────────────────────────────── ────
In Table 8, the unit “phr” of the mixing ratio of the aligning agents 1, 2, and 3 is the aligning agent 1 with respect to 100 parts by mass of the liquid crystal compound (in the case of mixing the liquid crystal compounds 1 and 2, the total amount is 100 parts by mass). 2 or 3 parts by mass are represented.
In addition, the composition ratio of the contents and the solvent is shown in the table as a mass ratio. Moreover, the solid content concentration (unit mass%) of the composition for retardation layer was described in the column of “Concentration” in the table.

  In this way, the laminated optical film No. 1 to 19 were produced.

<Evaluation of optical film>
About each obtained optical film, adhesiveness, the liquid crystal orientation of a phase difference layer, and the planar shape of the phase difference layer were evaluated.

1. Adhesion evaluation On the surface of each optical film having the phase difference layer, 11 vertical and 11 horizontal cuts were made with a cutter knife in a grid pattern, for a total of 100 1 mm square squares. The polyester adhesive tape “No. 31B” manufactured by Nitto Denko Co., Ltd. was crimped and subjected to an adhesion test. The presence or absence of peeling was visually observed, and the following four-stage evaluation was performed.
◎: No peeling was observed in 100 squares ○: No peeling was observed in 100 squares within 2 squares Δ: peeling was observed in 100 squares 3 to 10 mm x: 100 mm of which peeling was observed exceeded 10 mm

2. Evaluation of liquid crystal orientation Observation was performed with a polarizing microscope in a crossed Nicol environment, and observation was performed in a state where the film slow axis was arranged in parallel with at least one axis of a polarizing plate mounted on the microscope. At this time, the observation magnification used was a 20 × objective lens and a 10 × eyepiece lens. At this time, the liquid crystal layer was brought into focus, and when observed, Maltese cloth, bright spot failure, and schlieren structure were visually confirmed.
(Double-circle): The whole is very homogeneous and a bright spot is not seen.
○: The average number of bright spots per field is 1 or more and 10 or less.
Δ: The average number of bright spots per field of view is 10 or more and 40 or less.
X: Maltese cloth or bright spot failure and schlieren structure are seen throughout.

3. Phase evaluation of retardation layer (film optical unevenness)
The sample film was held between two polarizing plates placed in a crossed Nicol state, and illuminated with a backlight having a luminance of 10,000 cd / m ² from below the lower polarizing plate.
In addition, after setting the film so that the slow axis of the film between the polarizing plates is parallel to the absorption axis of the polarizing plate placed on the upper side, the viewing angle is 45 ° with respect to the slow axis of the film, and the viewing angle is 60 °. The optical unevenness was evaluated according to the following criteria.
A: Unevenness is not seen and it looks very homogeneous.
○: Slight unevenness is seen.
Δ: Unevenness appears thin on the entire surface.
X: It looks strong and clear.
The obtained results are shown in the following table.
The results are shown in Table 8 below.

The compounds used are shown below.
B01: Compound having the following structure.

  B02: Compound having the following structure.

  B03: Compound having the following structure

  S1: Compound having the following structure

  S2: Compound having the following structure

  S3: Compound having the following structure

In the above formula, a: b is 90:10 (mass ratio).
S4: Compound having the following structure

  S5: Compound having the following structure

  In the above formula, 32.5: 67.5 is a molar ratio.

As is clear from the results shown in the above table, the optical film No. 1 is a comparative example in which the support is a cyclic olefin film. 1 shows that it is inferior to the adhesiveness of each layer.
Comparative optical film No. 1 in which a specific acrylic layer was not formed between the support and the retardation layer. 3, although it has a specific acrylic layer, it is not formed between the support and the retardation layer. 4 is inferior to any of the adhesion, liquid crystal orientation, and retardation layer surface of each layer.
On the other hand, optical film No. of the Example which formed the specific acrylic layer between the support body and the phase difference layer. 2 and 4 to 19 are all excellent in adhesion, liquid crystal orientation, and retardation layer surface form of each layer, or are practically acceptable.

Claims (18)

  An acrylic layer containing an acrylic compound in which at least one hydroxyl group of a polyhydric alcohol compound is substituted with a (meth) acryloyl group and a polymerizable compound having a polar group and a polymerizable group on a cellulose acylate support An optical film having a retardation layer in which an alignment state of a liquid crystal material is fixed on the acrylic layer.   The optical film according to claim 1, wherein the acrylic compound is a polyfunctional acrylate having an average of 2 to 4 polymerizable groups.   The optical film according to claim 1, wherein the acrylic layer and the retardation layer are adjacent to each other.   The optical film according to claim 1, wherein the retardation layer contains a fluorine atom.   The optical film of any one of Claims 1-4 in which the said phase difference layer contains any element of a boron atom, a bromine atom, a nitrogen atom, and a sulfur atom.   The optical film according to claim 1, wherein the retardation layer is obtained by polymerizing a rod-like polymerizable liquid crystal compound having an ethylenically unsaturated bond at both ends of a rigid group.   The optical film according to claim 6, wherein the rod-like polymerizable liquid crystal compound is composed of a benzoate ester compound derivative.   The optical film according to claim 6 or 7, wherein the rod-like polymerizable liquid crystal compound forming the retardation layer is fixed in a homeotropic alignment state.   The ratio of the polymeric compound which has the polar group and polymeric group which are contained in the said acrylic layer is 30 mass% or more with respect to the sum total with the said polyhydric alcohol compound, The any one of Claims 1-8. An optical film according to item.   The optical film according to claim 1, wherein the acrylic compound and the polymerizable compound are the same compound.   The optical film according to claim 1, wherein the cellulose acylate is cellulose acetate.   The optical film of any one of Claims 1-11 whose average acyl substitution degree of the said cellulose acylate is 2.0-2.9.   The optical film according to any one of claims 1 to 12, wherein a retardation value Re in the in-plane direction of the support is from 70 to 150, and a retardation value Rth in the film thickness direction is from 70 to 200. .   The optical film of any one of Claims 1-13 whose film thickness of the said support body is 5-50 micrometers.   The optical film of any one of Claims 1-14 whose film thickness of the said acrylic layer is 0.15-2.0 micrometers.   The optical film of any one of Claims 1-15 whose film thickness of the said phase difference layer is 0.5-2.0 micrometers.   The optical film of any one of Claims 1-16 whose total film thickness of all the layers containing the said support body, the said acrylic layer, and the said phase difference layer is 20-50 micrometers.   A polymerizable composition comprising an acrylic compound in which at least one hydroxyl group of a polyhydric alcohol compound is substituted with a (meth) acryloyl group and a polymerizable compound having a polar group and a polymerizable group is coated on a cellulose acylate support. A step of forming an acrylic layer by film curing by heat or ultraviolet irradiation, a step of applying a polymerizable composition containing a polymerizable liquid crystal compound on the acrylic layer, and heat after orienting the polymerizable liquid crystal compound. Or the manufacturing method of an optical film which has the process of fixing an orientation state by ultraviolet irradiation.