JP6131709B2 - Optical film using polymer composition - Google Patents

Description

  The present invention relates to an optical film using a polymer composition, and more particularly to an optical film for a liquid crystal display having excellent retardation characteristics using a polymer composition.

  Liquid crystal displays are widely used as the most important display devices in the multimedia society, including cellular phones, computer monitors, laptop computers, and televisions. Many optical films are used in liquid crystal displays to improve display characteristics. In particular, the optical film plays a large role in improving contrast and compensating for color tone when viewed from the front or obliquely.

There are many liquid crystal displays such as vertical alignment type (VA-LCD), in-plane alignment type liquid crystal (IPS-LCD), super twist nematic type liquid crystal (STN-LCD), reflection type liquid crystal display, and transflective type liquid crystal display. There is a method, and an optical film suitable for the display is required.
In the case of a liquid crystal display in the IPS mode (the system used in the IPS-LCD), liquid crystal molecules rotate mainly in a plane parallel to the substrate. It is known that the difference in the degree of refractive index is small and thus the viewing angle is widened.

  As one means for improving the viewing angle and color tone of an IPS mode type liquid crystal display device, an optical material having birefringence characteristics is disposed between a liquid crystal layer and a polarizing plate. An electro-optical liquid crystal switching element in which a birefringent light compensation group is installed between a substrate and a polarizer in the IPS mode is disclosed (for example, see cited document 1). In the IPS mode, a birefringent medium is disposed between the substrate and the polarizing plate, and the angle formed by the polarizing axis of the polarizing plate and the slow axis direction of the birefringent medium is 20 ° to 60 °, preferably 30 ° to 50 °. Thus, it is disclosed that the problem of coloring yellow or blue when white display or halftone display is viewed directly from an oblique direction is solved (see, for example, cited document 2).

  However, the IPS mode has one drawback in terms of visual characteristics in principle. As one of the features of the IPS mode, liquid crystal molecules that are homogeneously aligned in the horizontal direction and two polarizing plates that are arranged so that the transmission axis is perpendicular to the top and bottom and left and right directions with respect to the front of the screen are used. When viewing the screen obliquely from the top, bottom, left, and right directions, the two transmission axes are in a positional relationship where they are perpendicular to each other, and the homogeneously aligned liquid crystal layer has little birefringence that occurs in the twisted mode liquid crystal layer. That is, sufficient contrast can be obtained. On the other hand, when the screen is viewed obliquely from a direction with an azimuth angle of 45 degrees, the transmitted light is birefringent because the angle formed by the transmission axes of the two polarizing plates appears to deviate from 90 degrees. As a result of light leakage, sufficient black cannot be obtained and the contrast is lowered. Further, as a result of a decrease in contrast, luminance inversion also occurs in the region from black to halftone. As described above, although the IPS mode has very good visual characteristics, there is a drawback that the contrast is reduced in the 45 degree direction. In order to solve this problem, display devices using various compensation films have been proposed. In particular, a biaxial film satisfying 0 <Nz <1 (that is, nx> nz> ny or ny> nz> nx) is produced even when a material having a positive or negative intrinsic refractive index is stretched as a single material. The biaxial film satisfying Nz = 0.5 has a retardation value that is substantially constant regardless of the viewing angle, and the viewing angle of the liquid crystal display device can be obtained by using such a retardation film. It is known that the characteristics are greatly improved, and it is very beneficial if it can be manufactured industrially at a low cost. However, such a film has a complicated structure or a problem in productivity, and its improvement is demanded.

  As a method for producing a retardation film, for example, there is a disclosure of a method for producing by a heat shrink treatment method using a heat shrink film, and it is disclosed that nz> nx ≧ ny can be realized (for example, Patent Documents). 3). In addition, there is a disclosure about a method for producing a retardation film including a region of (nx> nz> ny), and the manufacturing method also includes a direction in which heat shrinks (for example, see Patent Document 4). .

  However, when a retardation film is produced by such a method, productivity is very poor and an increase in cost has been a problem. Moreover, since the film made by this method is inferior in flatness, it is difficult to ensure the uniformity of retardation, and when a polarizing plate is produced using the film, it is uniform in a display device using the polarizing plate. There was a problem that it was difficult to obtain display quality.

  Further, there is a disclosure about a retardation film in which Nz satisfies 0.2 <Nz <0.7 by mixing cellulose ester and acicular fine particles such as a styrene polymer or strontium carbonate (for example, see Patent Document 5). . However, the retardation film disclosed so far is a retardation film including a region (ny> nz> nx), and a retardation film including a region (nx> nz> ny) has not been obtained. However, there is a problem that the degree of freedom in selecting a retardation film and peripheral materials in the development of an IPS liquid crystal display is limited. Moreover, although excellent transparency is required for the optical film used for the display device of the display, Patent Document 5 does not disclose transparency such as haze and light transmittance. Furthermore, in recent years, there has been a demand for weight reduction and thinning of IPS liquid crystal displays. However, the film disclosed in Patent Document 5 cannot sufficiently meet the demand for weight reduction and thinning.

  On the other hand, the retardation film is also used as a reflection type liquid crystal display device, a touch panel or an organic EL antireflection layer. In this application, a retardation film (hereinafter referred to as “reverse wavelength dispersion”) having a larger retardation in a longer wavelength region. Film)). When a reverse wavelength dispersion film is used as the antireflection layer, the retardation is preferably about ¼ of the measurement wavelength λ, and the ratio Re (450) / Re (550) of the retardation at 450 nm to the retardation at 550 nm is 0. It is preferably close to 81. And when the thickness reduction of a display apparatus is considered, it is calculated | required that the reverse wavelength dispersion film used is also thin. Various retardation films have been developed for the required characteristics as described above.

  As such a retardation film, a retardation plate having reverse wavelength dispersion obtained by blending a polymer having positive intrinsic birefringence and a polymer having negative intrinsic birefringence is disclosed (for example, And Patent Document 6). However, this document discloses a norbornene-based polymer as a polymer having positive intrinsic birefringence, a copolymer of styrene and maleic anhydride as a polymer having negative intrinsic birefringence, and a composition obtained by blending these polymers. In the retardation plate using the composition, Re is desirable as retardation characteristics of the retardation film, 105 nm ≦ Re ≦ 350 nm, and Nz is 0.2 <Nz <0.7. It does not meet.

Japanese Patent Laid-Open No. 9-80424 JP-A-5-505247 JP 2002-207123 A JP 2001-174632 A WO2006 / 117981 JP 2001-337222 A

  The present invention has been made in view of the above problems, and an object thereof is a film using a polymer composition having a retardation characteristic desirable as a retardation film, and is disclosed in Patent Document 5 (ny It is to provide an optical film having a three-dimensional refractive index relationship different from that of a retardation film including a region of> nz> nx) and a method for producing the optical film.

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

  The present invention is an optical film manufactured through a stretching process, wherein the retardation value Re represented by the following formula (i) satisfies 105 nm ≦ Re ≦ 350 nm, and is represented by the following formula (ii). Satisfying 0.2 <Nz <0.7, the stretching direction is x, the direction orthogonal to x in the film plane is y, and the thickness direction z of the film is nx> nz> ny. In the optical film satisfying the above, the optical film contains at least one polymer A exhibiting positive birefringence in the stretching direction and at least one material B, and the material B is negative with respect to the stretching direction. It is an optical film characterized by exhibiting birefringence.

Formula (i) Re = (nx−ny) × d
Formula (ii) Nz = (nx-nz) / (nx-ny)
However, the refractive index in the x direction is nx, the refractive index in the y direction is ny, the refractive index in the z direction is nz, and d indicates the thickness (nm) of the film.

  In the present invention, the retardation value Rth represented by the following formula (iii) is preferably in the range of −50 nm ≦ Rth ≦ + 50 nm.

Formula (iii) Rth = {(nx + ny) / 2−nz} × d
(Here, the refractive index in the stretching direction is nx, the refractive index in the direction perpendicular to x in the film plane is ny, the refractive index in the thickness direction of the film is nz, and d is the thickness (nm) of the film.)
In this invention, it is a preferable form that haze is 3% or less.

  In the present invention, the light transmittance is preferably 85% or more.

  In the present invention, it is preferable that the wavelength dispersion characteristic is 0.60 <Re (450) / Re (550) <1.05.

  In the present invention, the polymer A is preferably a cellulosic polymer.

  In the present invention, the material B is a polymer B exhibiting negative birefringence in the stretching direction, and the optical film preferably has the polymer A and the polymer B compatible with each other. is there.

  In the present invention, the material B is a polymer B exhibiting negative birefringence in the stretching direction, and the polymer B is also preferably localized in the polymer A.

  In the present invention, the material B is inorganic particles, and the inorganic particles are also dispersed in the polymer A in one of the preferable modes. The inorganic particles are more preferably acicular fine or spindle-shaped particles having an average major axis of 10 to 500 nm and an acicular ratio defined below of 1.5 or more.

Needle ratio = absolute maximum length / diagonal width Here, the diagonal width is the shortest distance between two straight lines when an image of a particle projected by two straight lines parallel to the absolute maximum length is sandwiched.

  In the present invention, the material B is a liquid crystalline compound B exhibiting negative birefringence with respect to the stretching direction, and the optical film is preferably such that the polymer A and the polymer B are compatible. It is a form.

  In the present invention, the material B is a liquid crystalline compound B exhibiting negative birefringence with respect to the stretching direction, and the polymer B is preferably localized in the polymer A. .

  Hereinafter, the present invention will be described in detail.

  The optical film of the present invention is an optical film produced through a stretching process, wherein the retardation value Re represented by the following formula (i) satisfies 105 nm ≦ Re ≦ 350 nm, and is represented by the following formula (ii). Nx> nz> where Nz satisfies 0.2 <Nz <0.7, the stretching direction is x, the direction perpendicular to x in the film plane is y, and the thickness direction z of the film is An optical film satisfying ny, wherein the optical film contains at least one polymer A and at least one material B exhibiting positive birefringence in the stretching direction, and the material B is in the stretching direction. It exhibits a negative birefringence with respect to.

Formula (i) Re = (nx−ny) × d
Formula (ii) Nz = (nx-nz) / (nx-ny)
However, the refractive index in the x direction is nx, the refractive index in the y direction is ny, the refractive index in the z direction is nz, and d indicates the thickness (nm) of the film.

  From the viewpoint of widening the viewing angle, Re of the optical film is preferably 120 nm ≦ Re ≦ 300 nm, and Rth is preferably an optical value of −50 nm ≦ Rth (a) ≦ + 50 nm.

  Here, the stretching direction is the direction of stretching performed in the process of producing the optical film. In the case of uniaxial stretching, the stretching direction, and in the case of stretching in two different directions, the direction in which the stretching ratio is large. Is the stretching direction.

  That is, the present inventors include a polymer A that exhibits positive birefringence in the stretching direction and a material B that exhibits negative birefringence in the stretching direction by being contained in the film and stretching. By adjusting the selection of the polymer A, the selection of the material B, and the combination thereof, the refractive index in the stretching direction is nx, the refractive index ny in the direction perpendicular to x in the film plane, When the refractive index in the thickness direction is nz, the retardation value Re satisfying the relationship of nx> nz> ny and represented by the above formula (i) is 105 nm ≦ Ro ≦ 350 nm, and the above formula (ii) The present inventors have found that an optical film having a represented Nz in a range of 0.2 <Nz <0.7 can be produced.

  The optical film of the present invention needs to contain at least one polymer (polymer A) exhibiting positive birefringence in the stretching direction.

  Whether or not the polymer A exhibits positive birefringence in the stretching direction can be determined by the following test method.

(Test method for birefringence of polymer A)
After only polymer A is dissolved in a solvent and cast into a film, the film is dried by heating, and birefringence is evaluated for a film having a transmittance of 80% or more.

  A Abbe refractometer-1T is used to measure the refractive index using a multi-wavelength light source, and the refractive index in the in-plane direction orthogonal to ny in the stretching direction is defined as nx. For films where (ny−nx)> 0 for each refractive index at 550 nm, polymer A is judged to be positively birefringent with respect to the stretch direction.

  The polymer A that can be used in the present invention is easy to manufacture, optically uniform, optically transparent, in addition to being a polymer showing a positive value in the birefringence test. It is preferable that the in-plane refractive index is large. Any of these may be used, for example, cellulose polymers such as cellulose ether, polyester polymers, polycarbonate polymers, polyarylate polymers, polysulfone (including polyethersulfone) polymers, polyester polymers. , Polyethylene-based polymers, norbornene-based polymers, cycloolefin-based polymers, acrylic-based polymers, and the like, but are not limited thereto. Among these, as the polymer for the optical film according to the present invention, a cellulose polymer, a polycarbonate polymer, and a cycloolefin polymer are preferable in terms of production, retardation characteristics, transparency, uniformity, adhesiveness, and the like. Cellulose polymers are more preferable, and cellulose ether is particularly preferable among cellulose polymers.

  The optical film of the present invention can also be used as a polarizing plate protective film, and when used in this application, the polymer A is a cellulosic polymer from the viewpoint of expressing surface wettability equivalent to that of a conventional TAC film. It is preferable that

  This is because the optical film of the present invention using a cellulose-based polymer can express surface wettability, and can be bonded as a polarizing plate protective film using a polyvinyl alcohol-based polarizer and a polyvinyl alcohol-based adhesive. This is because it can be done.

And when a cellulosic polymer is used in the present invention, the cellulosic polymer has excellent mechanical properties and excellent moldability during film formation, so that gel permeation chromatography (GPC) The number average molecular weight (Mn) in terms of standard polystyrene obtained from the elution curve measured by 1 is preferably 1 × 10 ³ to 1 × 10 ⁶ , and more preferably 5 × 10 ³ to 2 × 10 ⁵ .

  Hereinafter, cellulose ethers that are preferable as the polymer A used in the optical film of the present invention and that are particularly preferable cellulose ethers will be described.

  Cellulose ether, which is a cellulose polymer contained in the polymer composition of the present invention, is a polymer in which β-glucose units are linearly polymerized, and part of hydroxyl groups at the 2nd, 3rd and 6th positions of the glucose unit. Or it is the polymer which etherified all. Examples of the cellulose ether of the present invention include alkyl celluloses such as methyl cellulose, ethyl cellulose, and propyl cellulose; hydroxyalkyl celluloses such as hydroxyethyl cellulose and hydroxypropyl cellulose; aralkyl celluloses such as benzyl cellulose and trityl cellulose; and cyanoalkyls such as cyanethyl cellulose. Cellulose; Carboxyalkylcelluloses such as carboxymethylcellulose and carboxyethylcellulose; Carboxyalkylalkylcelluloses such as carboxymethylmethylcellulose and carboxymethylethylcellulose; Aminoalkylcelluloses such as aminoethylcellulose and the like.

  The degree of substitution of the cellulose ether in the cellulose ether through the oxygen atom of the cellulose is the ratio of the etherification of the hydroxyl group of cellulose for each of the 2-position, 3-position and 6-position (100% etherification is substitution) Degree 1), and from the viewpoint of solubility, compatibility, and stretch processability, the total substitution degree DS of the ether group is preferably 1.5 to 3.0 (1.5 ≦ DS ≦ 3.0). Yes, more preferably 1.8 to 2.8. It is preferable that a cellulose ether has a C1-C12 substituent from the point of solubility and compatibility. Examples of the substituent having 1 to 12 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, decanyl group, dodecanyl group, isobutyl group, and t-butyl group. Cyclohexyl group, phenonyl group, benzyl group, naphthyl group and the like. Among these, a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group, which are alkyl groups having 1 to 5 carbon atoms, are preferable from the viewpoint of solubility and compatibility. The cellulose group used in the present invention may have only one type of ether group or may have two or more types of ether groups. In addition to the ether group, it may have an ester group.

  Cellulose ether is generally synthesized by alkali-decomposing cellulose pulp obtained from wood or cotton and etherifying the alkali-decomposed cellulose pulp. As the alkali, hydroxides of alkali metals such as lithium, potassium and sodium, ammonia and the like can be used. The alkalis are generally used as an aqueous solution. And the cellulose pulp made into alkalinity is etherified by contacting with the etherifying agent used according to the kind of cellulose ether. Examples of etherifying agents include halogenated alkyls such as methyl chloride and ethyl chloride; aralkyl halides such as benzyl chloride and trityl chloride; halocarboxylic acids such as monochloroacetic acid and monochloropropionic acid; ethylene oxide, propylene oxide, butylene oxide and the like. These ether oxide agents can be used alone or in combination of two or more.

  If necessary, after completion of the reaction, depolymerization treatment may be performed with hydrogen chloride, hydrogen bromide, hydrochloric acid, sulfuric acid or the like for viscosity adjustment.

(Material B)
Next, the optical film of the present invention is characterized by containing at least one material B exhibiting negative birefringence in the stretching direction.

  The material B exhibiting negative birefringence in the stretching direction means a material that exhibits negative birefringence in the stretching direction in a medium or other polymer.

  In the present invention, the object of the present invention is achieved by drawing an optical film by drawing a material containing polymer A that exhibits positive birefringence in the drawing direction and at least one material B. The polymer A and the material B exhibiting positive birefringence with respect to the stretching direction can be carried out by appropriately selecting the contained ratio and the contained form in order to express the target retardation.

  Since the mass fractions of the polymer A and the material B constituting the optical film used in the present invention are convenient for the expression of the target retardation, 0 <[(material B) / (polymer A)] <2. The relationship is preferably 0, more preferably 0.01 <[(material B) / (polymer A)] <1.95, and 0.1 <[(material B) / (polymer A). )] <1.9 is particularly preferable.

  In order to control the birefringence of the optical film of the present invention, it is necessary to add at least one material B. However, two or more materials B that can exhibit the negative birefringence may be used. At this time, the seed is a seed of the material, and includes those having different shapes, molecular weights or compositions. As the material B, an organic compound can be used, and an inorganic compound may be used. Organic-inorganic hybrid compounds may also be used.

  The material B is not particularly limited as long as it exhibits negative birefringence in the stretching direction, but the material B is an organic material (polymer) that exhibits negative birefringence in the stretched direction. Since the birefringence of both the polymer A and the material B can be expressed by stretching in a state of being contained in the polymer, it is efficient and preferable for production.

  In the present invention, the optical film containing the polymer A and the material B is one of the preferable forms in which at least one of the polymers B is uniformly compatible as the polymer A and the material B. . When polymer B showing positive birefringence in the stretching direction is mixed with polymer B showing negative birefringence in the stretching direction, the retardation uniformity in the in-plane direction is very high. Can be obtained. Further, when the material B (polymer B) is uniformly compatible in the optical film, when the optical film is used in a polarizing plate or a liquid crystal display device including the same, the scattered light or phase other than the designed light is used. Can be effectively prevented from passing through the polarizing plate.

  In the present invention, the material B is a polymer B exhibiting negative birefringence in the stretching direction, and the polymer B is localized in the polymer A exhibiting negative birefringence in the stretching direction. This is one of the preferred forms from the viewpoint of easily exhibiting the above characteristics. In particular, when the material B (polymer B) is localized, a film in which fine particles of the material B having a particle size of visible light or less are dispersed is preferable from the viewpoint of suppressing generation of unnecessary scattered light.

  Further, when the material B is added to the polymer A to obtain the optical film of the present invention, in order to obtain the objective refractive index relationship of the present invention, the amount added is localized rather than being compatible. Less. This is preferable from the viewpoint that the characteristics (physical characteristics) of the polymer A are easily expressed in the film in terms of volume, and the characteristics of the material B can be efficiently used optically.

  The present invention adds a material B that exhibits a negative birefringence when stretched to a polymer A that exhibits a positive birefringence with respect to the stretching direction. One of the conditions is to show sex. The material B is not particularly limited as long as it is oriented by stretching and exhibits negative birefringence with respect to the orientation direction. Examples of the material that is oriented by stretching and exhibits negative birefringence include polystyrene and polymethyl methacrylate.

  Whether or not the material B (polymer B) exhibits negative birefringence when stretched can be determined by the following test method.

<Birefringence test of material B>
The material B is added to a polymer exhibiting positive birefringence in the stretching direction, dissolved in a solvent, cast into a film, dried by heating, and evaluated for birefringence for a film having a transmittance of 80% or more. Further, the Abbe refractometer 1T performs refractive index measurement using a multi-wavelength light source. The refractive index of nx in the stretching direction and the in-plane direction orthogonal to ny is defined as ny, and the difference of (nx−ny) for each refractive index of 550 nm is larger than the same refractive index difference of the film having the same draw ratio not including the material B. When showing a low value or a negative value, it is judged that the material B has a negative birefringence in the stretching direction.

<Polymer B>
In the optical film of the present invention, in order to control Nz to be 0.2 <Nz <0.7, it is preferable to include the polymer B that exhibits negative birefringence in the stretching direction. There is no particular limitation as long as it exhibits negative birefringence in the stretching direction. For example, it is preferable to contain a polymer having a weight average molecular weight of 1,000 to 100,000 obtained by polymerizing an ethylenically unsaturated monomer.

  Furthermore, the polymer B preferably contains an acrylic polymer having a weight average molecular weight of 1,000 or more and 100,000 or less because of compatibility with the polymer A and development characteristics of negative birefringence. An acrylic polymer having an aromatic ring in the side chain or an acrylic polymer having a cyclohexyl group in the side chain is more preferable.

  In particular, when the polymer A is a cellulosic polymer, the compatibility between the cellulosic polymer and the acrylic polymer is improved by controlling the composition of the acrylic polymer with a weight average molecular weight of 1000 to 100,000. And neither evaporation nor volatilization occurs during film formation. In particular, for an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, or an acrylic polymer having a cyclohexyl group in the side chain, if the weight average molecular weight is 1000 to 70000, in addition to the above, film formation The transparency of the subsequent cellulose polymer film is excellent, and the moisture permeability is extremely low. When the optical film of the present invention is used as a protective film for a polarizing plate, excellent performance is exhibited.

  When the polymer B has a weight average molecular weight of 700 or more and 50000 or less, it is considered that the polymer B is between the oligomer and the low molecular weight polymer. In order to synthesize such a polymer, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can align the molecular weight as much as possible by a method that does not increase the molecular weight so much. Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. Or a method using a chain transfer agent such as carbon tetrachloride, a method using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator, thioglycerol (1-Thioglycerol), 1-mercapto-2,3 -Propanediol, 2-mercapto-3-butanol, 2-mercapto-3,4-butanediol, 1-mercapto-2,3-butanediol, 1-mercapto-2-butanol, 2-mercapto-3,4, 4′-butanetriol, 1-mercapto-3,4-butanediol, 1-mercapto-3,4,4 ′ It can be mentioned a method in which bulk polymerization using one thiol group and secondary compounds having a hydroxyl group or a polymerization catalyst in combination with thiols and organometallic compounds, such as butane triol. Thiols include compounds having one thiol group and a secondary hydroxyl group, and functional groups other than thiol groups, such as ethyl mercaptan, butyl mercaptan, hexyl mercaptan, tertiary decyl mercaptan, normal dodecyl mercaptan, and octyl mercaptan. Thiol compounds such as aromatic thiols having no functional groups other than thiol groups such as alkyl thiols, phenyl mercaptan, benzyl mercaptan, β-mercaptopropionic acid, mercaptoethanol, 3-mercaptopropyl-trimethoxy Thiols having functional groups other than thiol groups, such as silane and thiophenol, and polyfunctional thiol compounds obtained by esterifying trithioglycerin or pentaerythritol with β-mercaptopropionic acid In addition, mention may be made of polymeric thiols such as having a thiol group of an active such as polysulfide polymers. Examples of organometallic compounds include dicyclopentadiene-Ti-dichloride, dicyclopentadiene-Ti-bisphenyl, dicyclopentadiene-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl Dicyclopentadiene-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, dicyclopentadiene-Ti-bis-2,5,6-trifluorophen-1-yl, dicyclopentadiene -Ti-bis-2,6-difluorophen-1-yl, dicyclopentadiene-Ti-bis-2,4-difluorophen-1-yl, dimethylcyclopentadienyl-Ti-bis-2,3,4 , 5,6-pentafluorophen-1-yl, dimethylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophene -1-yl, dimethylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, dimethylcyclopentadienyl-Ti-bis-2,6-difluoro-3- (pyru-1-yl ) -Phen-1-yl such as dicyclopentadienyl-Zr-dichloride, dicyclopentadiene-Zr-bisphenyl, dicyclopentadiene-Zr-bis-2,3,4,5,6- Pentafluorophen-1-yl, dicyclopentadiene-Zr-bis-2,3,5,6-tetrafluorophen-1-yl, dicyclopentadiene-Zr-bis-2,5,6-trifluoropheny 1-yl, dicyclopentadiene-Zr-bis-2,6-difluorophen-1-yl, dicyclopentadiene-Zr-bis-2,4-difluor Phenyl-1-yl, dimethylcyclopentadienyl-Zr-bis-2,3,4,5,6-pentafluorophen-1-yl, dimethylcyclopentadienyl-Zr-bis-2,3,5 6-tetrafluorophen-1-yl, dimethylcyclopentadienyl-Zr-bis-2,6-difluorophen-1-yl, dimethylcyclopentadienyl-Zr-bis-2,6-difluoro-3- ( Zirconocene compounds such as pyr-1-yl) -phen-1-yl; dicyclopentadienyl-V-chloride, bismethylcyclopentadienyl-V-chloride, bispentamethylcyclopentadienyl-V-chloride , Dicyclopentadienyl-Ru-chloride, dicyclopentadienyl-Cr-chloride, and the like.

  Although the monomer as a monomer unit which comprises the polymer B useful for this invention is mentioned below, it is not limited to this.

  The ethylenically unsaturated monomer unit constituting the polymer obtained by polymerizing the ethylenically unsaturated monomer is as a vinyl ester, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, caproic acid. Vinyl, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate Etc .; As acrylate ester, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n -, I-, s-), hexyl acrylate (n I-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic Cyclohexyl acid, acrylic acid (2-ethylhexyl), benzyl acrylate, phenethyl acrylate, acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3- Hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, etc .; The above acrylic acid ester is changed to methacrylic acid ester; Examples thereof include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid and the like. The polymer composed of the above monomers may be a copolymer or a homopolymer, and in terms of compatibility with the polymer A, a homopolymer of vinyl ester, a copolymer of vinyl ester, or a copolymer of vinyl ester and acrylic acid or methacrylic acid ester is preferable. .

  In the present invention, an acrylic polymer (simply referred to as an acrylic polymer) refers to a homopolymer or copolymer of acrylic acid or methacrylic acid alkyl ester having no monomer unit having an aromatic ring or a cyclohexyl group. An acrylic polymer having an aromatic ring in the side chain is an acrylic polymer that always contains an acrylic acid or methacrylic acid ester monomer unit having an aromatic ring. The acrylic polymer having a cyclohexyl group in the side chain is an acrylic polymer containing an acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group.

  Examples of the acrylate monomer having no aromatic ring and cyclohexyl group include, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-) , Nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid 2-methoxy-ethyl) acrylate (2-ethoxyethyl), etc., or the acrylic acid ester can be exemplified those obtained by changing the methacrylic acid ester.

  The acrylic polymer is a homopolymer or copolymer of the above monomer. Since these improve compatibility with a cellulose polymer, it is preferable to have 5-40 mass% of acrylic acid or a methacrylic acid ester monomer unit which has a hydroxyl group in this polymer.

  Examples of acrylic acid or methacrylic acid ester monomers having an aromatic ring include phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl), methacrylic acid (2 or 4-chlorophenyl), and acrylic acid (2 or 3 Or 4-ethoxycarbonylphenyl), methacrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), acrylic acid (o or m or p-tolyl), methacrylic acid (o or m or p-tolyl), benzyl acrylate, Examples include benzyl methacrylate, phenethyl acrylate, phenethyl methacrylate, and acrylic acid (2-naphthyl).

  In the acrylic polymer having an aromatic ring in the side chain in terms of compatibility with negative birefringence expression, the acrylic acid or methacrylic acid ester monomer unit having an aromatic ring has 20 to 40% by mass, and acrylic acid or It is preferable to have 40-80 mass% of methacrylic acid methyl ester monomer units. Moreover, in order to improve compatibility with a cellulose-type polymer, it is preferable to have 5-40 mass% of acrylic acid or a methacrylic acid ester monomer unit which has a hydroxyl group in this polymer.

  Examples of the acrylate monomer having a cyclohexyl group include cyclohexyl acrylate, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl), methacrylic acid (4-methylcyclohexyl), acrylic acid (4-ethylcyclohexyl), and methacrylic acid. (4-ethylcyclohexyl) and the like.

  In the acrylic polymer having a cyclohexyl group in the side chain in terms of compatibility with negative birefringence expression, the acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group has 20 to 40% by mass and 40 to 80% by mass. % Is preferable. Moreover, in order to improve compatibility with a cellulose-type polymer, it is preferable to have 5-40 mass% of acrylic acid or a methacrylic acid ester monomer unit which has a hydroxyl group in this polymer.

  A polymer obtained by polymerizing the above ethylenically unsaturated monomer, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, and an acrylic polymer having a cyclohexyl group in the side chain are all phases of a cellulose polymer. It has excellent solubility.

  In the case of an acrylic acid or methacrylic acid ester monomer having these hydroxyl groups, it is not a homopolymer but a structural unit of a copolymer. In this case, in order to improve the compatibility with the cellulose polymer, the acrylic acid or methacrylic acid ester monomer unit having a hydroxyl group is preferably contained in the acrylic polymer in an amount of 5 to 40% by mass.

  As acrylic acid or methacrylic acid ester monomer units having a hydroxyl group, acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), Examples include acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, or those obtained by replacing these acrylic acids with methacrylic acid.

  When the polymer as described above contains 5 to 40% by mass of the monomer unit having a hydroxyl group as described above, the compatibility with the cellulosic polymer, retention, and dimensional stability are excellent, and the moisture permeability is small. When the optical film of the invention is used as a protective film for a polarizing plate, it is particularly excellent in adhesiveness with a polarizer and has an effect of improving the durability of the polarizing plate.

  In the present invention, when the material B is blended with the cellulosic polymer, it may have a hydroxyl group at the end of the main chain of the acrylic polymer in order to provide compatibility. The method of having a hydroxyl group at the end of the main chain is not particularly limited as long as it has a hydroxyl group at the end of the main chain, but radical polymerization having a hydroxyl group such as azobis (2-hydroxyethylbutyrate). A method of using an initiator, a method of using a chain transfer agent having a hydroxyl group such as 2-mercaptoethanol, a method of using a polymerization terminator having a hydroxyl group, a method of having a hydroxyl group at the terminal by living ion polymerization, Thioglycerol (1-Thioglyserol), 1-mercapto-2,3-propanediol, 2-mercapto-3-butanol, 2-mercapto-3,4-butanediol, 1-mercapto-2,3-butanediol, 1 -Mercapto-2-butanol, 2-mercapto-3,4,4'-butanetriol, 1-me A polymerization catalyst using a compound having one thiol group and a secondary hydroxyl group, such as capto-3,4-butanediol, 1-mercapto-3,4,4′-butanetriol, or a combination of thiols and an organometallic compound The method of carrying out bulk polymerization using can be mentioned. Thiols include compounds having one thiol group and a secondary hydroxyl group, and functional groups other than thiol groups, such as ethyl mercaptan, butyl mercaptan, hexyl mercaptan, tertiary decyl mercaptan, normal dodecyl mercaptan, and octyl mercaptan. Thiol compounds such as aromatic thiols having no functional groups other than thiol groups such as alkyl thiols, phenyl mercaptan, benzyl mercaptan, β-mercaptopropionic acid, mercaptoethanol, 3-mercaptopropyl-trimethoxy Thiols having functional groups other than thiol groups, such as silane and thiophenol, and polyfunctional thiol compounds obtained by esterifying trithioglycerin or pentaerythritol with β-mercaptopropionic acid In addition, mention may be made of polymeric thiols such as having a thiol group of an active such as polysulfide polymers. Examples of organometallic compounds include dicyclopentadiene-Ti-dichloride, dicyclopentadiene-Ti-bisphenyl, dicyclopentadiene-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl Dicyclopentadiene-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, dicyclopentadiene-Ti-bis-2,5,6-trifluorophen-1-yl, dicyclopentadiene -Ti-bis-2,6-difluorophen-1-yl, dicyclopentadiene-Ti-bis-2,4-difluorophen-1-yl, dimethylcyclopentadienyl-Ti-bis-2,3,4 , 5,6-pentafluorophen-1-yl, dimethylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophene -1-yl, dimethylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, dimethylcyclopentadienyl-Ti-bis-2,6-difluoro-3- (pyru-1-yl ) -Phen-1-yl such as dicyclopentadienyl-Zr-dichloride, dicyclopentadiene-Zr-bisphenyl, dicyclopentadiene-Zr-bis-2,3,4,5,6- Pentafluorophen-1-yl, dicyclopentadiene-Zr-bis-2,3,5,6-tetrafluorophen-1-yl, dicyclopentadiene-Zr-bis-2,5,6-trifluoropheny 1-yl, dicyclopentadiene-Zr-bis-2,6-difluorophen-1-yl, dicyclopentadiene-Zr-bis-2,4-difluor Phenyl-1-yl, dimethylcyclopentadienyl-Zr-bis-2,3,4,5,6-pentafluorophen-1-yl, dimethylcyclopentadienyl-Zr-bis-2,3,5 6-tetrafluorophen-1-yl, dimethylcyclopentadienyl-Zr-bis-2,6-difluorophen-1-yl, dimethylcyclopentadienyl-Zr-bis-2,6-difluoro-3- ( Zirconocene compounds such as pyr-1-yl) -phen-1-yl; dicyclopentadienyl-V-chloride, bismethylcyclopentadienyl-V-chloride, bispentamethylcyclopentadienyl-V-chloride , Dicyclopentadienyl-Ru-chloride, dicyclopentadienyl-Cr-chloride, and the like. In the present invention, the polymer having a hydroxyl group at the terminal and / or the polymer having a hydroxyl group in a side chain has an effect of significantly improving the compatibility and transparency of the polymer.

  Furthermore, when the material B is blended with the cellulosic polymer, a polymer using styrenes as the ethylenically unsaturated monomer exhibiting negative birefringence in the stretching direction exhibits negative refraction. Is preferred. Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, and vinyl benzoic acid methyl ester. Although it is mentioned, it is not a thing limited to these. As the ethylenically unsaturated monomer exhibiting negative birefringence with respect to the stretching direction, a polymer having a condensed ring containing two or more aromatic rings in the side chain may be used. Examples of the polymer having a condensed ring containing two or more aromatic rings in the side chain include, but are not limited to, vinylnaphthalene, vinylpyrene, vinylazulene, and the like. It may be copolymerized with the exemplified monomers listed as the unsaturated ethylenic monomer, or may be used by being compatible with a cellulose polymer using two or more of the above-mentioned polymers for the purpose of controlling birefringence.

  Furthermore, in the optical film of the present invention, it is one of preferable modes to localize the polymer B exhibiting negative birefringence with respect to the stretching direction. In the following, the localized polymer is referred to as a polymer particle.

  The polymer particles referred to in the present invention are preferably nano-level polymer ultrafine particles having a particle size of several nanometers to several hundred nanometers in order to improve transparency, and exhibit a variety of surface effects because of their high specific surface area. .

  The particle size of the polymer particles of the present invention is specifically preferably a particle having a particle size of 1 nm to 500 nm, more preferably 10 nm to 350 nm, particularly preferably 10 nm to 150 nm, and most preferably 10 nm or more. 100 nm or less. If the thickness is less than 1 nm, the effect of controlling the birefringence may be insufficient, and if it exceeds 500 nm, the haze may be significantly increased. The particle diameter of the polymer particles in the present invention is defined as a value obtained on average as a volume particle diameter in terms of a sphere. The method of measurement may be determined using techniques such as, but not limited to, standard dynamic light scattering, small angle neutron scattering NMR diffusion, X-ray scattering, TEM image analysis and gel phase chromatography. it can. Specifically, an index of average particle diameter is obtained by gel permeation chromatography (GPC) elution time obtained for polymer particles. The particle size of the polymer particles can also be determined by comparing the polymer particles with a polystyrene standard having a known molecular weight and hydrodynamic radius. The gel permeation chromatography technique used uses a column containing 10 μm PL gel to elution the crosslinked polymer particles, elution of polystyrene standards with known molecular weight and hydrodynamic radius. This can be done by comparing with time.

  The material of the polymer particles is not particularly limited, but examples include (meth) acrylic, styrene, (meth) acryl-styrene, fluorine-substituted (meth) acrylic, and fluorine-substituted (meth) acryl-styrene. There may be mentioned polymer particles which are at least one (co) polymer selected from the system.

  The polymer particles as the (meth) acrylic (co) polymer can be used as a (co) polymer of a (meth) acrylic acid ester monomer or a copolymer with another monomer. . Examples of the (meth) acrylate monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, (meth) acrylic acid Butyl, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylic Acid nonyl, decyl (meth) acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, (meth ) Acrylic acid such as butoxyethyl acrylate and ethoxypropyl (meth) acrylate Acid alkyl esters; dialkylaminoalkyl (meth) acrylates such as diethylaminoethyl (meth) acrylate; (meth) acrylamides; (meth) acrylamides such as N-methylol (meth) acrylamide and diacetone acrylamide and glycidyl (meth) acrylates; (Poly) alkylene such as ethylene glycol diacrylate, diethyl glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate Diacrylate of glycols; Dimethacrylate of ethylene glycol, Dimethacrylate of diethylene glycol (Poly) such as dicarboxylic acid ester of triethylene glycol, dimethacrylic acid ester of polyethylene glycol, dimethacrylic acid ester of propylene glycol, dimethacrylic acid ester of dipropylene glycol, dimethacrylic acid ester of tripropylene glycol, etc. Examples thereof include dimethacrylic acid esters of alkylene glycol.

  Other monomers other than the (meth) acrylic monomer described above include, for example, styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl. Alkyl styrenes such as styrene and octyl styrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, chloromethylstyrene; styrenes such as nitrostyrene, acetylstyrene, methoxystyrene, α-methylstyrene, vinyltoluene Mention may be made of monomers.

  Furthermore, as monomers other than styrene monomers, for example, silicon-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl pivalate , Vinyl esters such as vinyl caproate, vinyl persuccinate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pt-butylbenzoate, vinyl salicylate; vinylidene chloride, vinyl chlorohexanecarboxylate, acrylic acid -2-chloroethyl, methacrylic acid-2-chloroethyl and the like.

  Furthermore, if necessary, as other monomers having a functional group, for example, acrylic acid, methacrylic acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, norbornene dicarboxylic acid, bicyclo [ 2,2,1] hept-2-ene-5,6-dicarboxylic acid and the like, and as derivatives thereof, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride Acid, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid anhydride, and the like. Furthermore, as a polymerizable reactive monomer having a hydroxyl group (OH; hydroxyl group), for example, acrylic acid 2-Hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropylene acrylate 1,1,1-trihydroxymethylethane triacrylate, 1,1,1-trishydroxymethylmethylethane triacrylate, 1,1,1-trishydroxymethylpropane triacrylate; hydroxy vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl Hydroxyalkyl vinyl ethers such as vinyl ethers; hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl acrylate, diethylene glycol mono (meth) acrylate, etc., and these alone or two or more monomers A composite can be used suitably suitably.

  The polymer particles formed from the above-described polymer can be appropriately prepared by soap-free emulsion polymerization, suspension polymerization, emulsion polymerization or the like. When preparing a polymer nanoparticle suspension by soap-free emulsion polymerization, it is generally sufficient that persulfates such as potassium persulfate and ammonium persulfate are soluble in an aqueous medium during polymerization as a polymerization initiator. In general, the polymerization initiator is preferably 0.1 to 10% by mass, the polymerization rate and the molecular weight of the resin are preferably 0.2 to 2% by mass with respect to 100 parts by mass of the polymerization monomer. It may be added in the range of. In the case of an emulsion polymerization method, a suspension thereof is prepared. As a polymerization initiator, a persulfate such as potassium persulfate or ammonium persulfate is used. An alkylbenzene sulfone such as sodium dodecylbenzenesulfonate is used with the above monomer as an emulsifier. An emulsifier such as an acid salt and polyethylene glycol alkyl ether such as polyethylene glycol nonylphenyl ether is usually 0.01 to 5% by mass, preferably 0.1 to 2% by mass based on 100% by mass of the polymerization monomer. It is mixed with a medium to make an emulsified state. Similarly, usually, the polymerization initiator may be added at 0.1 to 10% by mass, preferably 0.2 to 2% by mass with respect to 100% by mass of the polymerization monomer.

  Among these, in order to exhibit negative birefringence with respect to the stretching of the present invention, the composition of the polymer particles can be appropriately selected. Further, the polymer constituting the polymer particles is not limited by the molecular weight of the polymer that affects the compatibility, and the particle size for preventing light from scattering in the visible light region may be in the above range. In addition, the refractive index of the polymer nanoparticles is preferably a small difference in refractive index from the cellulose-based polymer A from the viewpoint of reducing scattering. Therefore, as polymer particles used for the cellulose polymer A, the average refractive index of the material constituting the polymer particles is preferably 1.33 or more and 1.8 or less, and more preferably 1.4 or more and 1.55 or less. The polymer constituting the polymer particles may include a slight cross-linked structure, and is not particularly limited as long as negative birefringence develops in the stretching direction as described above.

  The method for adding the polymer nanoparticles is not particularly limited, but may be added in-line with the matting agent described later.

  In addition, as a material B, use of inorganic particles exhibiting negative birefringence is one of the preferred embodiments of the present invention. When inorganic particles are used as the material B of the present invention, there is no particular limitation as long as it exhibits negative birefringence in the stretching direction, but unnecessary birefringence of visible light is avoided and effective birefringence is expressed. In view of the above, it is preferable to be acicular or spindle-shaped fine particles having an average value of the major axis of 10 to 500 nm and an acicular ratio defined below of 1.5 or more. Furthermore, in order to avoid unnecessary scattering, the acicular fine particles are preferably oriented in a specific direction, and the average azimuth angle of the acicular fine particles is orthogonal to the film surface of the optical film or The parallel direction is a preferred form.

Needle ratio = absolute maximum length / diagonal width Here, the diagonal width is the shortest distance between two straight lines when an image of a particle projected by two straight lines parallel to the absolute maximum length is sandwiched.

  As a method of dispersing and orienting the added fine particles, a method of stretching the film to TD or MD at the time of film production (casting), or a method of orienting the particles along the flow by creating a dope flow at the time of casting. It is possible to take etc. Furthermore, the orientation of particles can be promoted by an electric field or a magnetic field, and according to these methods, cutting properties (slitting properties) can be improved even when needle-like particles are added.

  As a method for producing an optical film containing these needle-shaped fine particles, an optical film for casting a solution using a dope prepared by mixing the fine particles having at least needle-like or spindle-like birefringence and polymer A is used. It can obtain by the manufacturing method of.

[Material for forming fine particle dispersion]
(Acicular fine particles with birefringence)
The needle-shaped or spindle-shaped fine particles having birefringence (hereinafter also referred to as birefringent fine particles) used in the present invention are not particularly limited as long as they are needle-shaped or spindle-shaped and have birefringence.

Examples of the birefringent fine particles include various carbonates such as calcium carbonate, strontium carbonate, magnesium carbonate, manganese carbonate, cobalt carbonate, zinc carbonate, and barium carbonate, various oxides represented by titanium oxide, MgSO _{4. 5Mg (OH) 2 · 3H 2} O, 6CaO · 6SiO 2 · H 2 O, 9Al 2 O 3 · 2B 2 O 3 birefringent whiskers of the like.

  For example, tetragonal, hexagonal and rhombohedral crystals are preferably uniaxial birefringent crystals, orthorhombic, monoclinic and triclinic crystals. These may be single crystals or polycrystals.

  Further, since the negative birefringence is increased, rod-like or short fiber particles of polystyrene or acrylic polymer are preferably used. For example, it may be a short fiber particle having a polystyrene polymer or an acrylic polymer and produced by finely cutting ultrafine fibers. These fibers are preferably stretched during the production process because they easily develop birefringence. Moreover, the polymer contained in these particles may be crosslinked.

  However, the present invention is not limited to these, and various types can be used as long as the above-described requirements such as size, shape, and needle ratio are satisfied.

  Since these birefringent fine particles exhibit a large negative birefringence with little decrease in transparency, it is preferable that the acicular ratio is 1.5 or more with a major axis (absolute maximum length) of 10 to 500 nm. The acicular ratio is more preferably 2 to 100, and particularly preferably 3 to 30. The acicular ratio is determined by the following equation from the absolute maximum length and the diagonal width of the fine particles. This can be determined from image data obtained by electron microscopic observation of fine particles or fine particles contained in the film.

Acicular ratio = absolute maximum length / diagonal width Here, the diagonal width is the shortest distance between two straight lines when an image of a particle projected by two straight lines parallel to the absolute maximum length is sandwiched. .

  The birefringent fine particles may be surface-treated with a silane coupling agent, a titanate coupling agent, or the like.

  The birefringence of the birefringent fine particles is defined as follows. The refractive index for light polarized in the major axis direction of the birefringent fine particles is npr, and the average refractive index for light polarized in the direction orthogonal to the major axis direction is nvt. The birefringence Δn of the birefringent fine particles is defined by the following formula.

Δn = npr−nvt
That is, if the refractive index in the major axis direction of the birefringent fine particles is larger than the average refractive index in the direction perpendicular thereto, positive birefringence is obtained, and if the opposite is true, negative birefringence is obtained.

  The absolute value of the birefringence possessed by the birefringent fine particles used in the present invention is not particularly limited, but is 0.01 to 0.3 for the purpose of expressing the target Nz when blended with the polymer A. It is preferable that it is 0.05-0.3.

The birefringent crystal having positive _{birefringence, MgSO 4 · 5Mg (OH)} 2 · 3H 2 O, 6CaO · 6SiO 2 · H 2 O, 9Al 2 O 3 · 2B 2 O 3, TiO 2 ( rutile Type crystal). Examples of the birefringent crystal exhibiting negative birefringence include calcium carbonate and strontium carbonate.

  In the case of acicular crystals, it means a material whose refractive index in the long direction of the crystal is smaller than the refractive index in the direction perpendicular thereto.

<Carbonate fine particles>
The carbonate fine particles can be produced by a uniform precipitation method or a carbon dioxide gas compounding method.

  The strontium carbonate crystal can be obtained by bringing strontium ions dissolved in water into contact with carbonate ions. Carbonate ions can be obtained by adding carbon dioxide gas to a solution containing a strontium compound by a method such as bubbling carbon dioxide, or by adding a substance that generates carbonate ions to react or decompose.

  Examples of substances that generate carbon dioxide include urea, a method of obtaining strontium carbonate fine particles by reacting carbon dioxide ions and strontium ions generated in combination with urea hydrolyzing enzyme (uniform precipitation method), and hydroxylation. There is a method (carbon dioxide compounding method) in which carbon dioxide gas is blown into a strontium suspension to react strontium ions with carbonate ions. In order to obtain fine crystals, it is preferable to lower the temperature as much as possible. Cooling below the freezing point is preferable because fine crystal particles can be obtained. For example, it is also preferable to add an organic solvent such as ethylene glycol as a freezing point depressing substance, and it is preferable to add so that the freezing point is below 5 ° C below freezing point. Thereby, fine particles of strontium carbonate having an average particle size in the major axis direction of 500 nm or less can be obtained.

  Strontium carbonate is a biaxial birefringent crystal, and the refractive index in the direction of each optical axis is n (na, nb, nc) = (1.520, 1.666, 1.669). The major axis direction of the crystal substantially coincides with the optical axis direction having a refractive index of 1.520. Therefore, it has a negative birefringence effect with respect to the orientation direction of the acicular crystal. Since the strontium carbonate crystal particles are in a needle-like (rod-like) form, they can be statistically oriented in a predetermined direction by applying a stress in a state of being dispersed in a viscous medium.

  As the fine particles having a needle shape or a spindle shape and having birefringence, a dispersing polymer having a weight average molecular weight of 3,000 to 200,000 may be used.

  From the viewpoint of dispersibility and compatibility with cellulosic polymers, a polymer for dispersing fine particles having a needle-like or spindle-like birefringence is a homopolymer or copolymer having an ethylenically unsaturated monomer unit, an acrylic polymer. Acid or methacrylic acid ester homopolymer or copolymer, methacrylic acid methyl ester homopolymer or copolymer, cellulose ester, cellulose ether, polyurethane polymer, polycarbonate polymer, polyester polymer, epoxy polymer and ketone polymer It is preferable that it is at least 1 type selected from. When a cellulose ester is used as the dispersing polymer, the cellulose ester preferably has a total acyl group substitution degree of 2.0 to 2.8 from the viewpoint of dispersibility and compatibility with the cellulose polymer.

  Even if these dispersing polymers are contained in a dope (cellulose concentration 15 to 30% by mass) which is a high-concentration cellulose ether solution used for solution casting, a uniform film is formed with little increase in haze. It can be a polymer.

  In the fine particle dispersion containing fine particles having a needle-like or spindle-like shape and birefringence, the concentration of the dispersing polymer is preferably 0.1 to 10% by mass in order to improve handling properties. Moreover, it is preferable that the density | concentration of microparticles | fine-particles in this dispersion liquid is 0.2-10 mass% for the improvement of handling property.

  In the present invention, it is preferable to control the viscosity of the fine particle dispersion in the range of 10 to 500 mPa · s in order to improve handling properties.

(Dispersant)
The fine particle dispersion or dope used in the present invention preferably contains a dispersant in order to improve dispersibility. The amount of the dispersant added is preferably 0.002 to 2% by mass, and 0.01 to 1% by mass with respect to the cellulose ether when cellulose ether is used in the present invention in order to more effectively express dispersibility. Is more preferable. As the dispersant, for example, a polymer dispersant such as a nonionic polymer dispersant, an anionic polymer dispersant, and a cationic polymer dispersant is appropriately selected.

  In order to uniformly disperse solid fine particles in a solvent or a polymer composition solution, it is known that a polymer dispersant that adsorbs to the solid fine particles is used. The polymer dispersant forms an adsorption layer on the surface of the solid fine particles, and the adsorption layer causes repulsion between the solid fine particles, thereby preventing the aggregation of the solid fine particles. Examples of the polymer used as the polymer dispersing agent for dispersing the fine particles include a homopolymer composed of a single monomer, a random copolymer composed of a plurality of monomers, and the like. A complex that includes both a part that interacts and adsorbs with the fine particles and a part that solvates and dissolves in the liquid from the surface of the solid fine particles in one molecule, and these two functions are divided into functions in one molecule. A polymer dispersant having a structure has been devised, and specifically, a comb polymer in which the functions of these two functions are shared is known as a good polymer dispersant.

  The content of the dispersant is preferably 0.0001 to 1% by mass in the dope or fine particle dispersion.

  In the present invention, the optical film containing the polymer A and the material B is one of the preferable forms in which at least one of the polymers B is uniformly compatible as the polymer A and the material B. . When the polymer A showing positive birefringence in the stretching direction is mixed with the liquid crystalline compound B showing negative birefringence in the stretching direction, the retardation uniformity in the in-plane direction However, a very excellent optical film can be obtained. Furthermore, when the material B (liquid crystalline compound B) is uniformly compatible in the optical film, when the optical film is used for a polarizing plate or a liquid crystal display device having the same, scattered light other than the designed light Alternatively, it is possible to effectively prevent light having different phases from being transmitted through the polarizing plate.

  In the present invention, the material B is a liquid crystalline compound B exhibiting negative birefringence in the stretching direction, and it is preferable that the material B is localized from the viewpoint of enhancing the expression of the liquid crystal and easily exhibiting the negative characteristics of the material B. One of the forms. In particular, when the material B (polymer B) is localized, a film in which fine particles of the material B having a particle size of visible light or less are dispersed is preferable from the viewpoint of suppressing generation of unnecessary scattered light.

  The domain size of the liquid crystal compound B of the present invention may be a domain size having a domain diameter of 1 nm or more and 500 nm or less in order to exhibit the effect of controlling the birefringence more sufficiently and to make the haze smaller. More preferably, it is 10 nm to 350 nm, particularly preferably 10 nm to 150 nm, and most preferably 10 nm to 100 nm. If the thickness is less than 1 nm, the effect of controlling the birefringence may be insufficient, and if it exceeds 500 nm, the haze may be significantly increased. The domain size of the liquid crystalline compound B in the present invention is defined as a value obtained on average as a volume particle diameter in terms of a sphere. The measurement method is not limited, but can be determined using techniques such as standard dynamic light scattering, small-angle neutron scattering NMR diffusion, X-ray scattering, and TEM image analysis.

<Liquid crystal compound B>
In the optical film of the present invention, it is preferable that the liquid crystalline compound B exhibiting negative birefringence in the stretching direction is contained, but the liquid crystalline compound exhibits negative birefringence in the stretching direction. There is no particular limitation. For example, a liquid crystalline compound in which rod-like liquid crystals are homeotropically aligned is preferable.

  The liquid crystal material that can be used in the liquid crystal composition is selected from a wide range regardless of whether it is a low-molecular liquid crystal material or a high-molecular liquid crystal material, depending on the intended use of the retardation film of the present invention and the performance required for it. However, a polymer liquid crystal substance is preferred because it is more suitable for expression of negative birefringence due to stretching orientation at the stretching temperature of the cellulosic polymer.

  Low molecular liquid crystal substances include saturated benzene carboxylic acids, unsaturated benzene carboxylic acids, biphenyl carboxylic acids, aromatic oxycarboxylic acids, Schiff base types, bisazomethine compounds, azo compounds, azoxy compounds, and cyclohexane ester compounds. A vinyl group, a (meth) acryloyl group, a vinyloxy group, an oxiranyl group, an oxetanyl group, a carboxyl group, a hydroxyl group, an amino group, an isocyanate group, an acid anhydride group, etc. Examples thereof include a compound exhibiting liquid crystallinity in which a reactive functional group is introduced, and a composition obtained by adding a crosslinkable compound to a compound exhibiting liquid crystallinity among the above compounds.

More specifically, the low-molecular liquid crystal substance is preferably a compound represented by the following formula (1) having a mesogenic group represented by MG for the expression of negative birefringence.
P- (Sp-X) n-MG-R (1)
In formula (1), P is the above-mentioned reactive functional group, and when a plurality of P are bonded, they may be the same or different. Sp is a spacer group having 1 to 20 carbon atoms, X is —O—, —S—, —CO—, —COO—, —OCO—, —OCOO— or a single bond, and n is , 0, 1, or 2, and MG is a mesogenic group or a mesogenic supporting group. For negative birefringence, this group is preferably represented by the following formula (2). R is selected from the group R is an alkyl group having up to 25 carbon atoms, which group is unsubstituted or substituted by one or more halogen or cyano groups, independently one more CH ₂ groups not CH ₂ group or adjacent the existing Further another respectively in, in the manner that oxygen atoms are not directly bonded to each other, -O -, - S-, _{-NH -, - N (CH 3} ) -, - CO -, - COO- , -OCO-, -OCO-O-, -S-CO-, -CO-S-, or -C≡C-, where R is also a halogen or cyano group, or independently And has one of the meanings indicated for P- (Sp-X) n-. In addition, when the compound represented by Formula (1) has several P, they may be the same or different.
_{- (A 1 -Z 1) m} -A 2 -Z 2 -A 3 - (2)
(In the formula (2), A ₁ , A ₂ and A ₃ are each independently a 1,4-phenylene group, and one or more CH groups present in this group are also represented by N Or a 1,4-cyclohexylene group, in which one CH ₂ group or _two non-adjacent CH ₂ groups are also O and / or Optionally substituted by S, or a 1,4-cyclohexenylene group or a naphthalene-2,6-diyl group, all of which are unsubstituted or one or more than one Optionally substituted by halogen, cyano group or nitro group, or by alkyl, alkoxy or alkanoyl groups having 1 to 7 carbon atoms, wherein one or more H atoms are F Others may be substituted by Cl, _{Z l} and _{Z 2} are each _{independently, -COO -, - OCO -,} - CH 2 CH 2 -, - OCH 2 -, - CH 2 O -, - CH ═CH—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH— or a single bond, and m is 0, 1 or 2.
As the polymer liquid crystal substance, various main chain type polymer liquid crystal substances, side chain type polymer liquid crystal substances, or a mixture (composition) thereof can be used.

  Main chain polymer liquid crystal materials include polyester, polyamide, polycarbonate, polyimide, polyurethane, polybenzimidazole, polybenzoxazole, polybenzthiazole, polyazomethine, polyesteramide, polyester carbonate Polymer liquid crystal substances such as polyester and polyesterimide, or mixtures thereof. Of these, liquid crystalline polyesters having the above reactive functional groups bonded are preferred from the viewpoints of ease of synthesis, orientation, glass transition point, and the like.

  Examples of the side chain type polymer liquid crystal material include materials having a linear or cyclic skeleton such as polyacrylate, polymethacrylate, polyvinyl, polysiloxane, polyether, polymalonate, and polyester. In addition, a polymer liquid crystal substance in which a mesogen group is bonded as a side chain, or a mixture thereof.

  More specifically, the (meth) acrylic part of the (meth) acrylic compound represented by the following general formula (3), which has a large negative birefringence expression, is homopolymerized or copolymerized with another (meth) acrylic compound. The side chain type liquid crystalline polymer material obtained in this way is preferably used.

（３）
式（３）中、Ｒ_１は水素またはメチル基を表し、Ｒ_２はシアノ基、炭素数１〜６のアルコキシ基、フルオロ基または炭素数１〜６のアルキル基を、Ｌ_１およびＬ_２はそれぞれ個別に単結合、−Ｏ−、−Ｏ−ＣＯ−、または−ＣＯ−Ｏ−のいずれかを表し、Ｍは式（４）、式（５）または式（６）を表し、ｎおよびｍはそれぞれ０〜１０の整数を示す。
−Ｐ_１−Ｌ_３−Ｐ_２−Ｌ_４−Ｐ_３− （４）
−Ｐ_１−Ｌ_３−Ｐ_３− （５）
−Ｐ_３− （６）
式（４）〜（６）中、Ｐ_１およびＰ_２はそれぞれ個別に式（７）から選ばれる基を表し、Ｐ_３は式（８）から選ばれる基を表し、Ｌ_３およびＬ_４はそれぞれ個別に単結合、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、−Ｏ−、−Ｏ−ＣＯ−または−ＣＯ−Ｏ−を表す。

(3)
In Formula (3), R ₁ represents hydrogen or a methyl group, R ₂ represents a cyano group, an alkoxy group having 1 to 6 carbon atoms, a fluoro group, or an alkyl group having 1 to 6 carbon atoms, and L ₁ and L ₂ represent Each independently represents a single bond, —O—, —O—CO—, or —CO—O—, M represents Formula (4), Formula (5), or Formula (6), and n and m Represents an integer of 0 to 10, respectively.
-P ₁ -L ₃ -P ₂ -L ₄ -P _3- (4)
-P ₁ -L ₃ -P _3- (5)
-P _3- (6)
In formulas (4) to (6), P ₁ and P ₂ each independently represent a group selected from formula (7), P ₃ represents a group selected from formula (8), and L ₃ and L ₄ are Each represents a single bond, —CH═CH—, —C≡C—, —O—, —O—CO— or —CO—O—.

（７）

(7)

（８）
式（７）において、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４ はそれぞれ水素、メチル基、エチル基、メトキシ基、ｎ−ブチル基、ｔ−ブチル基、クロライド基またはブロマイド基のいずれかを表す。

(8)
In the formula (7), R ₁ , R ₂ , R ₃ and R ₄ each represent hydrogen, methyl group, ethyl group, methoxy group, n-butyl group, t-butyl group, chloride group or bromide group. .

In the formula (8), R ₁ , R ₂ , R ₃ and R ₄ each represent hydrogen, methyl group, ethyl group, methoxy group, n-butyl group, t-butyl group, chloride group or bromide group. .

  In the exemplified side chain type liquid crystal polymer, the (meth) acrylic compound can be synthesized by a known method. The copolymer can be prepared, for example, according to a polymerization method such as a usual acrylic monomer such as a radical polymerization method, a cationic polymerization method, and an anionic polymerization method. When applying the radical polymerization method, various polymerization initiators can be used, and among them, azobisisobutyronitrile, benzoyl peroxide, and the like are preferably used.

  In addition, the (meth) acryl compound to be copolymerized at this time is not particularly limited, and is not limited as long as the synthesized polymer substance exhibits liquid crystallinity, but the synthesized polymer substance has liquid crystallinity. (Meth) acrylic compounds having a mesogenic group are preferred.

  In order to fix the liquid crystal alignment during film formation, a polymerizable liquid crystal compound may be contained, or a (meth) acrylic compound having an oxetanyl group represented by the following general formula (9) may be copolymerized.

（９）
上記式（９）中、Ｒ_１は水素またはメチル基を表し、Ｒ_２は水素、メチル基またはエチル基を表し、Ｌ_１およびＬ_２はそれぞれ個別に単結合、−Ｏ−、−Ｏ−ＣＯ−、または−ＣＯ−Ｏ−のいずれかを表し、Ｍは式（１０）、式（１１）または式（１２）を表し、ｎおよびｍはそれぞれ０〜１０の整数を示す。
−Ｐ_１−Ｌ_３−Ｐ_２−Ｌ_４−Ｐ_３− （１０）
−Ｐ_１−Ｌ_３−Ｐ_３− （１１）
−Ｐ_３− （１２）
式（１０）〜（１２）中、Ｐ_１およびＰ_２はそれぞれ個別に式（１３）から選ばれる基を表し、Ｐ_３は式（１４）から選ばれる基を表し、Ｌ_３およびＬ_４はそれぞれ個別に単結合、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、−Ｏ−、−Ｏ−ＣＯ−または−ＣＯ−Ｏ−を表す。

(9)
In the above formula (9), R ₁ represents hydrogen or a methyl group, R ₂ represents hydrogen, a methyl group or an ethyl group, and L ₁ and L ₂ each independently represents a single bond, —O—, —O—CO. -Represents either -CO-O-, M represents Formula (10), Formula (11), or Formula (12), and n and m each represent an integer of 0-10.
-P ₁ -L ₃ -P ₂ -L ₄ -P _3- (10)
-P ₁ -L ₃ -P _3- (11)
-P _3- (12)
In formulas (10) to (12), P ₁ and P ₂ each independently represent a group selected from formula (13), P ₃ represents a group selected from formula (14), and L ₃ and L ₄ are Each represents a single bond, —CH═CH—, —C≡C—, —O—, —O—CO— or —CO—O—.

（１３）

(13)

（１４）
式（１３）において、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４はそれぞれ水素、メチル基、エチル基、メトキシ基、ｎ−ブチル基、ｔ−ブチル基、クロライド基またはブロマイド基のいずれかを表す。

(14)
In the formula (13), R ₁ , R ₂ , R ₃ and R ₄ each represent any one of hydrogen, methyl group, ethyl group, methoxy group, n-butyl group, t-butyl group, chloride group or bromide group. .

In the formula (14), R ₁ , R ₂ , R ₃ and R ₄ each represent any one of hydrogen, methyl group, ethyl group, methoxy group, n-butyl group, t-butyl group, chloride group or bromide group. .

  The method for synthesizing these (meth) acrylic compounds having an oxetanyl group is not particularly limited, and can be synthesized by applying a method used in an ordinary organic chemical synthesis method. For example, by combining a site having an oxetanyl group and a site having a (meth) acrylic group by means such as Williamson's ether synthesis or ester synthesis using a condensing agent, oxetanyl group and (meth) acrylic group 2 A (meth) acrylic compound having an oxetanyl group having two reactive functional groups can be synthesized. However, in the reaction, since the oxetanyl group has cationic polymerizability, it is necessary to select reaction conditions in consideration of causing side reactions such as polymerization and ring opening under strong acidic conditions.

  The (meth) acrylic group having the oxetanyl group represented by the formula (9) is represented by the following formula (15) by homopolymerization or copolymerization with another (meth) acrylic compound. A side-chain liquid crystalline polymer substance containing units can be obtained. The polymerization conditions are not particularly limited, and normal radical polymerization or anionic polymerization conditions can be employed.

（１５）
さらに、液晶性組成物中に熱または光架橋反応等によって反応しうる官能基または部位を有している各種化合物を液晶性の発現を妨げない範囲で配合しても良い。架橋反応しうる官能基としては、前述の各種の反応性官能基などが挙げられる。

(15)
Furthermore, you may mix | blend the various compounds which have a functional group or site | part which can react by a heat | fever or a photocrosslinking reaction etc. in the liquid crystalline composition in the range which does not prevent liquid crystalline expression. Examples of the functional group capable of undergoing a crosslinking reaction include the various reactive functional groups described above.

  Specifically, for example, a dioxetane compound represented by the following general formula (16) is included.

（１６）
式（１６）において、Ｒ_１、Ｒ_２はそれぞれ個別に水素、メチル基またはエチル基を表し、Ｌ_１およびＬ_２はそれぞれ個別に単結合、−Ｏ−、−Ｏ−ＣＯ−、または−ＣＯ−Ｏ−のいずれかを表し、Ｍは式（１７）または式（１８）を表し、ｎおよびｍはそれぞれ０〜１０の整数を示す。
−Ｐ_１−Ｌ_３−Ｐ_１−Ｌ_４−Ｐ_１− （１７）
−Ｐ_１−Ｌ_３−Ｐ_１− （１８）
式（１７）〜（１８）中、Ｐ_１はそれぞれ個別に式（１９）から選ばれる基を表し、Ｌ_３およびＬ_４はそれぞれ個別に単結合、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、−Ｏ−、−Ｏ−ＣＯ−または−ＣＯ−Ｏ−を表す。

(16)
In Formula (16), R ₁ and R ₂ each independently represent hydrogen, a methyl group, or an ethyl group, and L ₁ and L ₂ each independently represent a single bond, —O—, —O—CO—, or —CO -O- is represented, M represents Formula (17) or Formula (18), and n and m each represent an integer of 0 to 10.
_{-P 1 -L 3 -P 1 -L 4} -P 1 - (17)
-P ₁ -L ₃ -P _1- (18)
In formulas (17) to (18), P ₁ each independently represents a group selected from formula (19), L ₃ and L ₄ each independently represent a single bond, —CH═CH—, —C≡C— , -O-, -O-CO- or -CO-O-.

（１９）
式（１９）において、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４はそれぞれ水素、メチル基、エチル基、メトキシ基、ｎ−ブチル基、ｔ−ブチル基、クロライド基またはブロマイド基のいずれかを表す。

(19)
In the formula (19), R ₁ , R ₂ , R ₃ and R ₄ each represent hydrogen, methyl group, ethyl group, methoxy group, n-butyl group, t-butyl group, chloride group or bromide group. .

  The liquid crystalline composition used in the present invention may be the above liquid crystalline compound alone, or a mixture of various liquid crystalline compounds or a composition containing various activators and additives, as long as it exhibits liquid crystallinity. There is no particular limitation. These liquid crystalline compositions are compositions exhibiting liquid crystallinity, and preferably contain at least 10% by mass of the low-molecular liquid crystal substance or the high-molecular liquid crystal substance because of the convenience of the liquid crystallinity of the composition. 30% by mass or more is more preferable, and 50% by mass or more is particularly preferable. When the content of the low-molecular liquid crystal substance or the high-molecular liquid crystal substance is less than 10% by mass, the concentration of the compound exhibiting liquid crystallinity in the composition becomes low, and the composition may not exhibit liquid crystallinity, which is not preferable.

  The liquid crystalline composition having a reactive group is allowed to react under conditions suitable for reacting the reactive group after realizing a desired alignment.

  Examples of the reaction initiator include organic peroxides, azo compounds and various photopolymerization initiators used for general radical polymerization.

  Examples of the photopolymerization initiator include a photo radical initiator that cleaves with appropriate light to generate radicals, and a photo cation generator that cleaves with appropriate light to generate cations. If necessary, a thermal cation generator that can generate cations when heated to an appropriate temperature can also be used.

As the photo radical initiator, commercially available benzoin ethers, acyl phosphine oxides, triazine derivatives, biimidazole derivatives generally used for known ultraviolet (UV) curable paints, UV curable adhesives, negative resists, etc. And the like.
Examples of the photocation generator include organic sulfonium salt systems, iodonium salt systems, phosphonium salt systems, and the like. Examples of counter ions of these compounds include antimonate, phosphate, borate and the like. Specific examples of the compound include Ar ₃ S ⁺ SbF ₆ ⁻ , Ar ₃ P ⁺ BF ₄ ⁻ , Ar ₂ I ⁺ PF ⁶⁻ (wherein Ar represents a phenyl group or a substituted phenyl group) and the like. In addition, sulfonate esters, triazines, diazomethanes, β-ketosulfone, iminosulfonate, benzoinsulfonate, and the like can also be used.

  Examples of the thermal cation generator include benzylsulfonium salts, benzylammonium salts, benzylpyridinium salts, benzylphosphonium salts, hydrazinium salts, carboxylic acid esters, sulfonic acid esters, amine imides, antimony pentachloride-acetyl chloride complex And diaryl iodonium salt-dibenzyloxy copper, boron halide-tertiary amine adduct, and the like.

  Next, the alignment layer used in the present invention will be described.

  In the present invention, when a liquid crystalline composition is used as the material B, the alignment of the liquid crystalline composition is preferably homeotropic alignment, and the liquid crystalline composition formed on a thermoplastic polymer film or an alignment substrate. An alignment layer capable of forming homeotropic alignment in a liquid crystal state is necessary. The formation of the alignment layer is not particularly limited as long as the liquid crystalline composition can be homeotropically aligned. Some thermoplastic polymer films and alignment substrates exhibit a sufficient homeotropic alignment ability for the liquid crystalline composition used in the present invention without performing a treatment for expressing the alignment ability again. However, when the orientation ability is insufficient or does not show the orientation ability, various physical treatments, chemical treatments, or a combination of these treatments can be used.

  Examples of the physical treatment include stretching under moderate heating, performing a so-called rubbing treatment in which the film surface is rubbed in one direction with a rayon cloth or the like, or forming a Langmuir-Blodgett film. As the chemical treatment, a known alignment agent such as a polyimide having a long-chain alkyl group (usually having 4 or more carbon atoms, preferably 8 or more) bonded to the film, a surfactant such as polyvinyl alcohol or a silane coupling agent, and the like. For example, a vapor deposition treatment of silicon oxide or the like provided with an alignment film made of Alternatively, homeotropic alignment ability may be expressed by appropriately combining them.

  As a method for forming a liquid crystalline composition layer by spreading the liquid crystalline composition on the thermoplastic polymer film or the alignment substrate, the liquid crystalline composition is applied on the thermoplastic polymer film or the alignment substrate in a molten state. And a method of applying a solution of a liquid crystalline composition on a thermoplastic polymer film or an alignment substrate and then drying the coating film to distill off the solvent.

  The solvent used for preparing the solution is not particularly limited as long as it can dissolve the liquid crystalline composition used in the present invention and can be distilled off under suitable conditions. Moreover, in order to form a uniform coating film on a thermoplastic polymer film or an alignment substrate, a surfactant, an antifoaming agent, a leveling agent, or the like may be added to the solution.

(Additive)
The following various materials can be used as additives in the optical film of the present invention.

  In the dope for producing the optical film of the present invention, a plasticizer, an ultraviolet absorber, an antioxidant, a dye, a matting agent, a retardation adjusting agent and the like can be added.

  These compounds may be added together with the polymer A or a solvent during the preparation of the polymer A solution, or may be added during or after the solution preparation. In particular, in addition to the retardation adjusting agent that improves the optical characteristics, a plasticizer, an antioxidant, an ultraviolet absorber, or the like that imparts heat and moisture resistance may be added to the liquid crystal display device.

<Plasticizer>
In the optical film of the present invention, a compound known as a plasticizer may be added for the purpose of improving mechanical properties, imparting flexibility, imparting water absorption resistance, reducing water vapor permeability, adjusting retardation, etc. Examples of the agent include phosphate esters and carboxylic acid esters. Acrylic polymers are also used. Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, phenyl diphenyl phosphate, and the like. Examples of the carboxylic acid ester include phthalic acid ester and citric acid ester. Examples of the phthalic acid ester include dimethyl phthalate, diethyl phthalate, dicyclohexyl phthalate, dioctyl phthalate, and diethyl hexyl phthalate. Examples include triethyl and acetyl tributyl citrate. Other examples include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin, trimethylolpropane tribenzoate, alkylphthalylalkyl glycolate, and the like. It is preferably used for this purpose. The alkyl in the alkylphthalylalkyl glycolate is an alkyl group having 1 to 8 carbon atoms. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate, Ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, propyl phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl Phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl Collate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl glycolate and the like can be mentioned, methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, Octyl phthalyl octyl glycolate is preferable, and ethyl phthalyl ethyl glycolate is more preferably used. Two or more of these alkylphthalylalkyl glycolates may be used in combination.

  The addition amount of these compounds is preferably 1% by mass to 30% by mass with respect to the polymer A from the viewpoints of achieving the desired effect and suppressing bleeding out from the film. In order to suppress bleed out, a plasticizer having a vapor pressure at 200 ° C. of 1333 Pa or less is preferable.

<Ultraviolet absorber>
Examples of the ultraviolet absorber used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. A benzotriazole-based compound with a low content is preferred. Hydroxyphenyl triazine is also used. As an ultraviolet absorber, from the viewpoint of preventing deterioration of a polarizer and a liquid crystal, it has an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display properties, it has little absorption of visible light having a wavelength of 400 nm or more. Is preferred.

  Specific examples of the benzotriazole ultraviolet absorber useful in the present invention include 2- (2-hydroxy-4-octyloxyphenyl) -2H-benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzo Triazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-(3 ", 4", 5 ", 6 ″ -Tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethyl) Butyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H -Benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazole- And a mixture of 2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate However, it is not limited to these. Further, as specific examples of the benzotriazole ultraviolet absorbers, commercially available products such as TINUVIN 109, TINUVIN 171, TINUVIN 326 (both manufactured by Ciba Specialty Chemicals), SEASORB 707 (manufactured by Sipro Kasei Co., Ltd.) can also be mentioned.

  Specific examples of benzophenone compounds include 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5. -Sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenylmethane) and the like can be mentioned, but are not limited thereto. Moreover, as a specific example of the benzophenone-based compound, a commercially available product such as SEESORB 106 (manufactured by Sipro Kasei Co., Ltd.) can be given.

  The ultraviolet absorber described above preferably used in the present invention is preferably a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber, which has high transparency and is excellent in the effect of preventing the deterioration of the polarizing plate and the liquid crystal element, and unnecessary coloring. Is more preferably used. The UV absorber can be added to the dope without limitation as long as the UV absorber dissolves in the dope. For example, the UV absorber can be used for cellulose esters such as methylene chloride, methyl acetate, and dioxolane. Solvent or mixed with a good solvent and a poor solvent such as a lower aliphatic alcohol (methanol, ethanol, propanol, butanol, etc.) and dissolved in an organic solvent and mixed with a cellulose ester solution as an ultraviolet absorber solution to form a dope, etc. Can be mentioned. In this case, in order to improve the mixing property, it is preferable that the dope solvent composition and the solvent composition of the ultraviolet absorber solution are made the same or as close as possible. The content when an ultraviolet absorber is used is preferably 0.01% by mass to 5% by mass, and preferably 0.5% by mass to 3% by mass for effective ultraviolet absorption within a range where no bleed or bloom occurs. Is more preferable.

<Antioxidant>
Examples of the antioxidant include hindered phenol compounds. Specifically, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1 , 3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -Isocyanurate etc. are mentioned. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t A phosphorus-based processing stabilizer such as -butylphenyl) phosphite may be used in combination. Here, when a cellulose ether is used as the polymer A in the optical film of the present invention, the amount of these compounds added is 1 ppm to 1. ppm with respect to the cellulose ether in order to suppress bloom / bleed and to exhibit an antioxidant effect. 0 mass% is preferable, and 10 ppm to 1000 ppm is more preferable.

<Retardation adjuster>
The polymer composition suitable for the optical film of the present invention may contain an additive having an aromatic hydrocarbon ring or an aromatic heterocycle for the purpose of adjusting the retardation. There is no particular limitation on the birefringence Δn (shown by the following formula (20)) of the additive used for the purpose of adjusting the phase difference, but it is preferably 0 because it becomes an optical film having excellent optical characteristics. 0.05 or more, more preferably 0.05 to 0.5, and particularly preferably 0.1 to 0.5. Note that nx and ny necessary for calculating Δn of the additive can be obtained by molecular orbital calculation.

Δn = ny−nx (20)
(In the formula, nx represents the refractive index in the fast axis direction of the additive molecule, and ny represents the refractive index in the slow axis direction of the additive molecule.)
The additive having an aromatic hydrocarbon ring or aromatic heterocycle in the polymer composition of the present invention is not particularly limited as to the number of aromatic hydrocarbon rings or aromatic heterocycles in the molecule, but the optical characteristics The number is preferably 1 to 12, more preferably 1 to 8, since the optical film is excellent in the above. Examples of the aromatic hydrocarbon ring include a 5-membered ring, a 6-membered ring, a 7-membered ring, or a condensed ring containing two or more aromatic rings. Examples of the aromatic heterocycle include a furan ring. Thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring, 1,3,5-triazine ring and the like.

  The aromatic hydrocarbon ring or aromatic heterocycle may have a substituent. Examples of the substituent include a hydroxyl group, an ether group, a carbonyl group, an ester group, a carboxylic acid residue, an amino group, and an imino group. Amide group, imide group, cyano group, nitro group, sulfonyl group, sulfonic acid residue, phosphonyl group, phosphonic acid residue and the like.

  Examples of the additive having an aromatic hydrocarbon ring or aromatic heterocycle used in the present invention include tricresyl phosphate, trixylenyl phosphate, triphenyl phosphate, 2-ethylhexyl diphenyl phosphate, cresyl diphenyl phosphate, and bisphenol. A phosphate compounds such as bis (diphenyl phosphate); dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dinormal octyl phthalate, 2-ethylhexyl phthalate, diisooctyl phthalate, dicapryl phthalate, dinonyl phthalate, diisononyl phthalate , Phthalate compounds such as didecyl phthalate and diisodecyl phthalate; tributyl trimellitate, tri-normal hexyl Trimellitic acid ester compounds such as rimerimate, tri (2-ethylhexyl) trimellitate, tri-normal octyl trimellitate, tri-isooctyl trimellitate, tri-isodecyl trimellitate; tri (2-ethylhexyl) pyromellitate, Pyromellitic acid such as tetrabutyl pyromellitate, tetra-normal hexyl pyromellitate, tetra (2-ethylhexyl) pyromellitate, tetra-normal octyl pyromellitate, tetra-isooctyl pyromellitate, tetra-isodecyl pyromellitate Ester compounds; benzoic acid ester compounds such as ethyl benzoate, isopropyl benzoate, ethyl paraoxybenzoate; phenyl salicylate, p-octylphenyl salicylate, p-tert-butylphenyl Salicylic acid ester compounds such as ricylate; Glycolic acid ester compounds such as methylphthalylethyl glycolate, ethylphthalylethyl glycolate, butylphthalylbutyl glycolate; 2- (2′-hydroxy-5′-t-butyl) Benzotriazole compounds such as phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole; 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy Benzophenone compounds such as -4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, N-benzenesulfonamide Sulfonamides such as Compounds, 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-ethoxyphenyl) -1 , 3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-butoxyphenyl) -1 , 3,5-triazine and the like, preferably tricresyl phosphate, 2-ethylhexyl diphenyl phosphate, 2-hydroxy-4-methoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxy A benzophenone etc. are mentioned, These can be used 1 type or in combination of 2 or more type as needed.

  The ratio of the additive having an aromatic hydrocarbon ring or aromatic heterocycle in the polymer composition of the present invention is 0 to 30% by mass for effective retardation adjustment in a range where bleed and bloom do not occur. It is preferable (the polymer component: 70 to 99.99% by mass), more preferably 0 to 20% by mass, and particularly preferably 0 to 15% by mass.

<Matting agent>
In the case where cellulose ether is used as the polymer A in the optical film of the present invention, it is possible to facilitate conveyance and winding by including a matting agent in the cellulose ether film. Since the matting agent is excellent in transparency, it is preferably as fine as possible. Examples of the fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, and hydration. Examples thereof include inorganic fine particles such as calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate, and crosslinked polymer fine particles. Of these, silicon dioxide is preferred because it can reduce the haze of the film.

  In many cases, fine particles such as silicon dioxide are surface-treated with an organic material, but such particles are preferable because they can reduce the haze of the film.

  As organic materials preferable for the surface treatment, halosilanes, alkoxysilanes, silazanes, siloxanes, and the like can be used. The larger the average particle size of the fine particles, the greater the sliding effect. On the other hand, the smaller the average particle size, the better the transparency. Therefore, the average particle size of the secondary particles of the fine particles is in the range of 0.05 μm to 1.0 μm. It is preferably 5 nm to 50 nm, more preferably 7 nm to 14 nm. These fine particles are preferably used in a cellulose ether film in order to generate irregularities of 0.01 μm to 1.0 μm on the surface of the cellulose ether film. The content of the fine particles in the cellulose ether is preferably 0.005% by mass to 0.3% by mass with respect to the cellulose ether from the viewpoint of slipperiness and transparency.

  Examples of the silicon dioxide fine particles include Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, and TT600 manufactured by Nippon Aerosil Co., Ltd. Two or more kinds of these fine particles may be used in combination. When using 2 or more types together, it can mix and use in arbitrary ratios. In this case, fine particles having different average particle sizes and materials, for example, Aerosil 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9: 0.1.

  When an alignment layer or a liquid crystal layer is applied, if the alignment is hindered by the unevenness of the matting agent, the matting agent can be contained only in the surface layer on one surface. Alternatively, a coating liquid containing these matting agents and cellulose ether can be applied to reduce the coefficient of friction and improve the slipperiness.

<Other additives>
In addition, thermal stabilizers such as inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, and alumina, and alkaline earth metal salts such as calcium and magnesium may be added. Furthermore, an antistatic agent, a flame retardant, a lubricant, an oil agent, etc. may be added.

(Organic solvent)
When cellulose ether is used as the polymer A in the optical film of the present invention, examples of organic solvents useful for forming a dope that dissolves cellulose ether include chlorinated solvents such as methylene chloride and chloroform; aromatics such as toluene and xylene. Group solvents; alcohol solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, and propanol; ether solvents such as dioxane and tetrahydrofuran; dimethylformamide, N-methylpyrrolidone, and the like can be used. When these organic solvents are used for cellulose ether, a dissolution method at normal temperature can be used, but an insoluble material can be obtained by using a dissolution method such as a high-temperature dissolution method, a cooling dissolution method, or a high-pressure dissolution method. Can be reduced, which is preferable.

  From the viewpoint of improving the film surface quality, the concentration of the polymer A and the material B in the dope is adjusted to 10% by mass to 40% by mass, and the dope viscosity is adjusted to a range of 10 Pa · s to 50 Pa · s. Is preferred.

(Optical film manufacturing method)
The optical film can be produced by a known solution casting method or melt extrusion method.

  The optical film can exhibit birefringence by stretching.

  A film containing a solvent can be stretched during the production of the solution casting method, or a film in a state where the solvent is dried can be stretched.

  When cellulose ether is used as the polymer A in the optical film of the present invention, when the cellulose ether and the material B are uniformly mixed, the film has a glass transition temperature of −40 ° C. or lower and a flowing temperature or lower. Can be stretched as Here, the glass transition temperature of the film can be measured by a known method.

  The film constituent material can be stretched in a melted state to form a film or diluted in a solvent to form a film. The birefringence can be controlled by stretching in a temperature range of -40 ° C. or higher.

  When cellulose ether is used as the polymer A in the optical film of the present invention and the cellulose ether and the material B are non-uniform (when the material B is localized), an additive is present in the cellulose ether. When at least one of the continuous phase and the region of the material B is stretched by satisfying the stretching condition, birefringence can be controlled. The stretching conditions are preferable methods from the viewpoint of obtaining a transparent film and controlling birefringence.

  The optical film of the present invention preferably has a retardation value Re of 105 nm ≦ Re ≦ 350 nm and Nz of 0.2 <Nz <0.7 in order to suppress light leakage at an oblique angle of 45 degrees and increase contrast. Rth is −50 nm ≦ Rth ≦ + 50 nm. In these ranges, it is known to particularly improve the viewing angle of the IPS mode.

<Control of three-dimensional refractive index>
When the optical film of the present invention is produced, it is characterized by satisfying the relationship of nx>nz> ny by stretching with the stretching direction defined as x.

  This is because when an optical film is manufactured, the direction in the film plane is defined as x and the direction perpendicular to the same plane is defined as y, and the thickness direction is z, and the refractive index of the film corresponding to these directions. Can control the refractive index three-dimensionally in these three directions when the refractive index corresponding to x is nx, the refractive index corresponding to y is ny, and the refractive index corresponding to the z direction is nz. This is important in the present invention.

  In the present invention, when the three-dimensional refractive index (nx, ny, nz) of the optical film is controlled, the optical film is a polymer having a positive birefringence with respect to the stretching direction and a negative with respect to the stretching direction. A material B exhibiting a birefringence of 2 is used. In this case, a tenter is preferably used because the film surface can be continuously stretched as fixed-width stretching having high smoothness.

  At this time, when a film containing no material B is produced by the method of the present invention from the configuration of the present invention, the relationship of nx (a)> ny (a)> nz (a) is obtained when the stretching direction is x. .

  Here, nx (a), ny (a), and nz (a) are the refractive index nx (a) in the stretching direction and the film in the stretching direction when the stretching direction is x in the polymer film not including the material B. The refractive index ny (a) in the direction orthogonal to the in-plane and the refractive index nz (a) in the thickness direction are shown. This is a conventional stretched cellulose polymer film, for example, a film represented by Konica Minolta Opto (manufactured by KC8UCR-3), and has a three-dimensional refractive index relationship different from that of the present invention.

  When an optical film is produced, since the material B is present in the film, it exhibits negative birefringence with respect to the stretching direction. At this time, when paying attention to the birefringence derived from the material B, nx (b) ≈ny (b) <nz (b) which is negative uniaxial when the material B is oriented with respect to the stretching direction of the film. A material satisfying the above relationship is used.

  Here, the above nx (b), ny (b), and nz (b) are the refractive index of the material B expressed by the orientation when the film is stretched, and the refractive index in the stretching direction when the stretching direction is y. nx (b), the refractive index ny (b) in the direction orthogonal to the film plane in the stretching direction, and the refractive index nz (b) in the thickness direction are shown.

  At this time, in the three-dimensional refractive index of the optical film, the film is stretched by defining the stretching direction as x, and in order to satisfy the relationship of nx> nz> ny, the optical contribution to the birefringence by the material B is In consideration of this, the compounding ratio and stretching conditions must be determined. The optical film of the present invention is characterized in that the material B has a specific blending ratio and stretching conditions, so that the optical contribution by the material is appropriate and has excellent optical properties. .

<Reverse wavelength dispersion of optical film>
When ethyl cellulose is used as the polymer A, an optical film having only low wavelength dispersion can be provided by itself. When this film is blended with material B exhibiting negative birefringence in the stretching direction, an optical film generally exhibiting reverse wavelength dispersion can be provided. The wavelength dispersion characteristic of the optical film of the present invention is preferably 0.60 <Re (450) / Re (550) <1.05, and more preferably 0.61 <Re (in order to suppress color shift. 450) / Re (550) <1.02.

  The draw ratio of the optical film of the present invention is preferably stretched in a unidirectional stretch ratio of 1.01 to 5.00 times in order to obtain better retardation development and stretch processability, and the other stretch ratio. Is stretched into a film of 1.00 to 2.50 times, more preferably the unidirectional stretch ratio is stretched to 1.1 to 4.00 times, and the other stretch ratio is 1.00 to 2.00. Stretched at 2.00 times, more preferably stretched in one direction at a stretch ratio of 1.3 to 4.00 times, and stretched at the other stretch ratio to less than 1.01 to 1.50 times Particularly preferably, the stretch ratio in one direction is stretched to 1.3 to 4.00 times, and the other stretch ratio is stretched to less than 1.01 to 1.25 times. Most preferably, the stretching ratio in one direction is stretched to 1.3 to 3.50 times, and the other Shin magnification of which has been stretched to less than 1.01 to 1.25 times. Thereby, while being able to obtain the optical film which has the retardation value of this invention preferably, an optical film with favorable flatness can be obtained. These width holding or lateral stretching in the film forming step can be continuously stretched as a fixed width stretching having a high smoothness on the film surface, and therefore is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

  When cellulose ether is used as the polymer A in the optical film of the present invention, the thickness of the cellulose ether film varies depending on the purpose of use, but from the viewpoint of thinning the liquid crystal display device, the finished film is preferably in the range of 10 to 120 μm. Further, a range of 20 to 100 μm is more preferable, and a range of 20 to 80 μm is particularly preferable. If the film is too thin, for example, when the optical film of the present invention is used as a polarizing plate protective film, the required strength as a polarizing plate protective film may not be obtained. If it is too thick, there is a case where the superiority of the thin film is lost over the conventional film.

  The physical properties of the optical film according to the present invention are summarized below.

(Transmittance of optical film)
As a member of an LCD display device, high transmittance and ultraviolet absorption performance are required, and a 500 nm transmittance (visible light transmittance) of an optical film produced by adding a combination of the above-mentioned additives is 85% to 100%. 90% to 100% is more preferable, and 92% to 100% is particularly preferable. The 400 nm transmittance is preferably 40% to 100%, more preferably 50% to 100%, and particularly preferably 60% to 100%. The 380 nm transmittance (ultraviolet light transmittance) is preferably 0% to 10%, more preferably 0% to 5%, and particularly preferably 0% to 3%.

  When the optical film is stretched in the width direction, it is preferable to stretch the film under conditions that control the film haze value after the stretching to a certain range. Since the film haze value is more suitable as the transparency required for the optical film, it is preferably 3% or less, more preferably 1.5%, particularly preferably 1% or less.

(Arithmetic mean roughness of optical film (Ra))
When an optical film is used as an LCD member, high flatness is required to reduce the light leakage of the film. The arithmetic average roughness (Ra) is a numerical value defined in JIS B 0601: 2001, and examples of the measuring method include a stylus method or an optical method.

  The arithmetic average roughness (Ra) of the optical film of the present invention is preferably 20 nm or less, more preferably 10 nm or less, particularly preferably 4 nm or less, for preventing light scattering (for transparency). is there.

  Below, the outline | summary of the measuring method used in the measuring method of the measured value which concerns on the optical film of this invention, and the Example mentioned later is demonstrated.

(Structural analysis of polymers and liquid crystal compounds)
The structural analysis of the polymer and the liquid crystal compound was determined by proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) spectrum analysis using a nuclear magnetic resonance measuring apparatus (manufactured by JEOL, trade name: JNM-GX270).

(Measurement of weight average molecular weight)
Using a gel permeation chromatography (GPC) apparatus (manufactured by Tosoh Corporation, trade name: C0-8011 (equipped with column GMH _HR- H)), measurement was performed at 40 ° C. using tetrahydrofuran or dimethylformamide as a solvent, It calculated | required as a standard polystyrene conversion value.

(Measurement of refractive index in slow axis direction, refractive index in fast axis direction, refractive index in thickness direction, and slow axis direction)
Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), wavelength dispersion measurement is performed, and an average refractive index of the sample is input from the Abbe refractometer 1T for retardation measurement at 550 nm. Refractive indexes nx, ny, and nz were obtained.

(Measurement of haze and total light transmittance of optical film)
The haze and total light transmittance of the prepared film were measured with a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: NDH2000), and the light transmittance was measured with JIS K 7361-1 (1997 edition). Were measured according to JIS-K 7136 (2000 edition).

  According to the present invention, it is possible to provide a polymer composition suitable for an optical film and an optical film having excellent retardation characteristics using the polymer composition.

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

(Preparation of optical film of the present invention)
<Polymer A>
As the polymer A, ethyl cellulose which is cellulose ether (ETHOCEL standard 100 manufactured by Dow Chemical), molecular weight Mn = 55,000, molecular weight Mw = 176,000, Mw / Mn = 3.2, total substitution degree DS = 2 .5) was used.

  About the said polymer A (cellulose ether), as a result of testing the birefringence with respect to an extending | stretching direction by the above-mentioned test method, the positive birefringence with respect to the extending | stretching direction was shown.

(Dope composition)
Hereinafter, it shows about dope composition of a cellulose ether film.

Ethyl cellulose 100 parts by mass Solvent: 400 parts by mass of methylene chloride Ethanol 100 parts by mass The following materials B Table 2 amounts <Material B (polymer)>
Polymers 1 to 7 (Material B) shown in Table 1 were synthesized by a known solution polymerization method. The polymers 1 to 7 were tested for birefringence in the stretching direction by the test method described above. As a result, the birefringence in the stretching direction was negative.

ドープ液を、Ｔダイ法により溶液流延装置の支持体に流延し、幅１５０ｍｍのポリマー組成物（光学フィルム）を得た。得られた光学フィルムを５０ｍｍ角に切り出し、自由端一軸延伸した（延伸後の厚み４０μｍ）。得られた光学フィルムのヘーズ、全光線透過率、位相差特性を測定した。その結果を表２に示す。

The dope solution was cast on a support of a solution casting apparatus by a T-die method to obtain a polymer composition (optical film) having a width of 150 mm. The obtained optical film was cut into a 50 mm square and uniaxially stretched at the free end (thickness after stretching: 40 μm). The obtained optical film was measured for haze, total light transmittance, and retardation characteristics. The results are shown in Table 2.

(Dope composition)
Hereinafter, it shows about dope composition of a cellulose ether film.

Ethylcellulose 100 parts by mass Solvent: Methylene chloride 400 parts by mass Ethanol 100 parts by mass Material B in the following dispersion liquid Table 3 amount <Material B in the dispersion liquid (needle or spindle-shaped fine particles)>
89 parts by mass of dichloromethane, strontium carbonate particles exhibiting negative birefringence (average size of major axis diameter 250 nm, aspect ratio 3.5, average intrinsic birefringence = na − ((nb + nc) / 2) = − 0.147510 mass A mixture of 1 part by weight of a part and a dispersant (BYK-Chemie, trade name Disperbyk-140) is stirred with a thin film swirl mixer (trade name: Filmics 56-50) manufactured by Primix Co., to obtain a strontium carbonate dispersion. Got.

  The dope solution was cast on a support of a solution casting apparatus by a T-die method to obtain a polymer composition (optical film) having a width of 150 mm. The obtained optical film was cut into a 50 mm square and uniaxially stretched at the free end (thickness after stretching: 40 μm). The obtained optical film was measured for haze, total light transmittance, and retardation characteristics. The results are shown in Table 3.

(Dope composition)
Hereinafter, it shows about dope composition of a cellulose ether film.

Ethylcellulose 100 parts by mass Solvent: Methylene chloride 400 parts by mass Ethanol 100 parts by mass The following material B Table 4 amount <Material B (liquid crystalline compound)>
Material B (liquid crystal polymer) of the following formula (21) was synthesized by a known method. The weight average molecular weight was 21,000. In addition, although Formula (21) is described with the structure of a block copolymer, it represents the component ratio of a monomer.

（２１）
ドープ液を、Ｔダイ法により溶液流延装置の支持体に流延し、幅１５０ｍｍのポリマー組成物（光学フィルム）を得た。得られた光学フィルムを５０ｍｍ角に切り出し、自由端一軸延伸した（延伸後の厚み４０μｍ）。得られた光学フィルムのヘーズ、全光線透過率、位相差特性を測定した。その結果を表４に示す。

(21)
The dope solution was cast on a support of a solution casting apparatus by a T-die method to obtain a polymer composition (optical film) having a width of 150 mm. The obtained optical film was cut into a 50 mm square and uniaxially stretched at the free end (thickness after stretching: 40 μm). The obtained optical film was measured for haze, total light transmittance, and retardation characteristics. The results are shown in Table 4.

  When the refractive index nx in the stretching direction, the refractive index ny in the direction orthogonal to x in the film plane, and the refractive index nz in the thickness direction of the film were measured by the following procedure, the optical film of the present invention was measured. In all of Examples 1 to 37, the relationship of nx> nz> ny was satisfied. From the refractive index obtained and the film thickness d (nm), Re, Rth, and Nz were determined by the following methods. The results are shown in Tables 2-4.

得られた光学フィルムは、光線透過率が高く透明性に優れ、ヘーズが小さく、面内位相差（Ｒｅ）およびＮｚ係数が目的とする光学特性を有するものであった。

The obtained optical film had high light transmittance and excellent transparency, a small haze, and the in-plane retardation (Re) and Nz coefficient had the desired optical characteristics.

(Measurement of Re, Rth, Nz)
When the refractive index nx in the stretching direction, the refractive index ny in the direction perpendicular to x in the film plane, and the refractive index nz in the thickness direction of the film are used, an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) is used. Three-dimensional birefringence measurement and chromatic dispersion measurement were performed. The average refractive index of the material constituting the film and the thickness of the film obtained by Abbe refractometer 1T at a wavelength of 550 nm are input, and the values of equations (i), (ii), and (iii) at 550 nm are measured values. I asked more.

Formula (i) Re = (nx−ny) × d
Formula (ii) Nz = (nx-nz) / (nx-ny)
Formula (iii) Rth = {(nx + ny) / 2−nz} × d
<Production of Comparative Optical Film (Polymer A: Ethylcellulose)>
(Dope composition)
Hereinafter, it shows about dope composition of a cellulose ether film.

Ethylcellulose 100 parts by weight Solvent: Methylene chloride 400 parts by weight Ethanol 100 parts by weight Material B Not added The dope solution is cast on a support of a solution casting apparatus by the T-die method, and a polymer composition (optical film) having a width of 150 mm is obtained. Obtained. The obtained optical film was cut into a 50 mm square and uniaxially stretched at the free end (thickness after stretching: 40 μm). The obtained optical film was measured for haze, total light transmittance, and retardation characteristics. The results are shown in Table 5.

  When the refractive index nx in the stretching direction, the refractive index ny in the direction orthogonal to x in the film plane, and the refractive index nz in the thickness direction of the film of the obtained optical film were measured, Comparative Example 1 to Comparative Example 2 The optical film had high light transmittance and excellent transparency and small haze, but had a relationship of nx> ny> nz, and the Nz coefficient did not have the desired optical characteristics.

＜比較の光学フィルムの作製（ポリマーＡ：セルロースアセテートプロピオネート（アセチル基＝５モル％、プロピオニル基＝８０モル％、全置換度ＤＳ＝２．５５、数平均分子量＝７５，０００））＞
（ドープ組成）
以下、セルロースエステルフィルムのドープ組成について示す。

<Production of Comparative Optical Film (Polymer A: Cellulose Acetate Propionate (Acetyl Group = 5 mol%, Propionyl Group = 80 Mol%, Total Substitution DS = 2.55, Number Average Molecular Weight = 75,000))>
(Dope composition)
Hereinafter, it shows about dope composition of a cellulose-ester film.

Cellulose acetate propionate 100 parts by mass Solvent: Methylene chloride 400 parts by mass Ethanol 100 parts by mass The following material B Table 7 amount <Material B (comparative polymer)>
Comparative Examples 3 to 4: Polymers 8 to 9 shown in Table 6 were synthesized by a known solution polymerization method.
Comparative Example 5: The acicular fine particles used in Examples 22 to 31 were used.
Comparative Example 6: Film formation was evaluated without adding material B.

  The dope solution was cast on a support of a solution casting apparatus by a T-die method to obtain a polymer composition (optical film) having a width of 150 mm. The obtained optical film was cut into a 50 mm square and uniaxially stretched at the free end (thickness after stretching: 40 μm). The haze and retardation characteristics of the obtained optical film were measured. The results are shown in Table 7.

  The obtained optical film was measured for the refractive index nx in the stretching direction, the refractive index ny in the direction perpendicular to x in the film plane, and the refractive index nz in the thickness direction of the film.

  The optical films of Comparative Examples 3 to 5 satisfied the relationship of nx> nz> ny, but Re was insufficient, the light transmittance was low, the transparency was inferior, and the haze was large.

  The optical film of Comparative Example 6 had high light transmittance and excellent transparency and small haze, but the Nz coefficient did not have the desired optical characteristics.

Claims (6)

An optical film manufactured through a stretching process, wherein a retardation value Re represented by the following formula (i) satisfies 105 nm ≦ Re ≦ 350 nm, and Nz represented by the following formula (ii) is 0.2. <Nz <0.7, an optical film satisfying the relationship of nx>nz> ny, where x is the stretching direction, y is the direction perpendicular to x in the film plane, and z is the thickness direction of the film. The optical film contains a polymer A which is a cellulose ether exhibiting positive birefringence in the stretching direction, and a material B which is an acrylic polymer or an acrylic polymer having an aromatic ring or a cyclohexyl group in the side chain. The optical film is characterized in that the material B exhibits negative birefringence with respect to the stretching direction.
Formula (i) Re = (nx−ny) × d
Formula (ii) Nz = (nx-nz) / (nx-ny)
However, the refractive index in the x direction is nx, the refractive index in the y direction is ny, the refractive index in the z direction is nz, and d indicates the thickness (nm) of the film. An optical film manufactured through a stretching process, wherein a retardation value Re represented by the following formula (i) satisfies 105 nm ≦ Re ≦ 350 nm, and Nz represented by the following formula (ii) is 0.2. <Nz <0.7, an optical film satisfying the relationship of nx> nz> ny, where x is the stretching direction, y is the direction perpendicular to x in the film plane, and z is the thickness direction of the film. In the optical film, the polymer A which is a cellulose ether exhibiting positive birefringence with respect to the stretching direction, the average value of the major axis is 10 to 500 nm, and the acicular ratio defined by the following formula (a) An optical film comprising a material B which is a needle-like or spindle-shaped fine particle having a diameter of 1.5 or more, and the material B exhibits negative birefringence in the stretching direction.
  Formula (i) Re = (nx−ny) × d
  Formula (ii) Nz = (nx-nz) / (nx-ny)
  However, the refractive index in the x direction is nx, the refractive index in the y direction is ny, the refractive index in the z direction is nz, and d indicates the thickness (nm) of the film.
  Formula (a) Needle-shaped ratio = absolute maximum length / diagonal width
  Here, the diagonal width is the shortest distance between two straight lines when an image of a particle projected by two straight lines parallel to the absolute maximum length is sandwiched. The retardation value Rth represented by following formula (iii) exists in the range of -50nm <= Rth <= + 50nm, The optical film of Claim 1 or Claim 2 characterized by the above-mentioned.
Formula (iii) Rth = {(nx + ny) / 2−nz} × d
(Here, the refractive index in the stretching direction is nx, the refractive index in the direction perpendicular to x in the film plane is ny, the refractive index in the thickness direction of the film is nz, and d is the thickness (nm) of the film.) The optical film according to any one of claims 1 to 3, wherein the haze is 3% or less. The optical film according to any one of claims 1 to 4 , wherein the light transmittance is 85% or more. The ratio Re (450) / Re (550) of the retardation at 450 nm to the retardation at 550 nm is 0.60 <Re (450) / Re (550) <1.05. Item 6. The optical film according to any one of Items 5 .