JP2005242337A - Polymer film and preparation method of polymer solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a retardation of produced polymer film by enhancing the solubility to a polymer solvent. <P>SOLUTION: A polymer is swollen in a first tank 31. The swelling temperature is in the range of -10 to 50°C. The mixture is cooled in a first cooler 32 to the range of -100 to -10°C and, thereafter, is heated in a heating part 35 to the range of 0 to 57°C. The polymer is cellulose acylate in which a degree of substitution of the acyl group for hydroxyl group is at least 2.87. A film obtained from the cellulose acylate has negative ΔRe and positive ΔRth, and ¾ΔRth¾ of at least 10 nm. The ΔRe and ΔRth are respective differences of Re and Rth at the measurement thereof with use of wavelengths between 700 nm and 400 nm. The film can be used suitably in a image display device as a retardation film and a protective film for polarizing plate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polymer film, a polarizing plate, and a method for preparing a polymer solution, and in particular, a polymer film that can be suitably used for an optical compensation film and an image display device, and the polymer film is produced by a solution casting method. It is related with the preparation method of the polymer solution used in order to do, and a polarizing plate.

  Polymers represented by cellulose esters, polyesters, polycarbonates, cycloolefin polymers, vinyl polymers, and polyimides are used in silver halide photographic light-sensitive materials, retardation plates (retardation films), polarizing plates, and image display devices. . These polymer films are generally produced by a solution casting (solvent cast) method or a melt casting (melt cast) method. For example, Patent Document 1 melts a cycloolefin copolymer having a relatively low melting point Tm and glass transition point Tg. A method for producing a film for optical use by a film forming method has been proposed. On the other hand, in the solution casting method, a polymer solution in which a polymer is dissolved in a solvent is cast on a continuously transported support, and when the polymer solution has self-supporting property, it is peeled off as a film from the support. It is a method that is produced by evaporating the film, and can be manufactured more excellent in terms of flatness and uniformity compared to the melt film-forming method, and is widely used as a film manufacturing method for optical applications. Yes. As a production example of a film for optical use by solution casting, a cellulose ester film widely used as a protective film for a silver halide photographic light-sensitive material or a polarizing plate is representative.

  As a solvent for preparing a polymer solution for forming a cellulose ester film, a chlorinated hydrocarbon such as dichloromethane is used. On the other hand, a search for a solvent for a cellulose ester other than a chlorinated organic solvent has also been made. ing. For example, as an organic solvent having solubility in cellulose ester, particularly cellulose triacetate, acetone (boiling point 56 ° C.), methyl acetate (boiling point 56 ° C.), tetrahydrofuran (boiling point 65 ° C.), 1,3-dioxolane (boiling point 75 ° C.), 1,4-dioxane (boiling point 101 ° C.). However, these organic solvents cannot be dissolved by the conventional dissolution method enough for practical use by the solution casting method. Therefore, dissolution using a method of dissolving cellulose ester at low temperature (cooling dissolution method) is also used. Improvements have been made. For example, in Non-Patent Document 1, cellulose triacetate (degree of acetylation 60.1% to 61.3%) is cooled to −80 ° C. to −70 ° C. in acetone and then heated to 0.5 mass. It has been reported that dilute solutions of 5% to 5% by weight can be obtained. Non-Patent Document 2 proposes a spinning technique using a cooling dissolution method. Patent Documents 2 to 4 propose a method of preparing a solution by dissolving cellulose acylate by a cooling dissolution method using a non-chlorine organic solvent against the background of the above technique.

  By the way, liquid crystal display devices (LCDs) that are in great demand among image display devices include transmissive LCDs and reflective LCDs, both of which have a liquid crystal cell and a polarizing plate. In a transmissive LCD, polarizing plates are attached to both sides of a liquid crystal cell, and one or more optical compensation films may be disposed. On the other hand, in a reflective LCD, a reflector, a liquid crystal cell, one or more optical compensation films, and a polarizing plate are usually arranged in this order. The retardation plate may be used as the optical compensation film.

  The polarizing plate generally has a protective film and a polarizing film. For example, a polarizing film made of a polyvinyl alcohol film is dyed with iodine and stretched, and protective films are laminated on both sides of the polarizing film. can get. The liquid crystal cell includes a liquid crystal molecule, two substrates for encapsulating the liquid crystal molecule, and an electrode layer for applying a voltage to the liquid crystal molecule. The liquid crystal cell performs both ON and OFF display depending on the alignment state of liquid crystal molecules, and various display modes that can be applied to both transmissive and reflective LCDs have been proposed. The display modes are TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensated Bend), VA (Vertically Aligned Concentrated), and ECB (Electrically Concentrated Bending).

  In recent years, for retardation plates and polarizing plate protective films, there has been a demand for improved compensation of retardation with the wide viewing angle of LCDs. For example, for applications that require high display quality, among the various modes described above, there are many TN modes that use nematic liquid crystal molecules having positive dielectric anisotropy and are driven by a thin film transistor and are 90-degree twisted nematic. Although it is used, this TN mode has excellent display characteristics when viewed from the front, but the contrast is lowered when viewed from an oblique direction, or gradation inversion that reverses the brightness in gradation display. This has a viewing angle characteristic that the display characteristic deteriorates due to the occurrence of the above, and this improvement is strongly demanded.

  Therefore, as an LCD method for improving the viewing angle characteristics, nematic liquid crystal molecules having negative dielectric anisotropy are used, and the major axis of the liquid crystal molecules is aligned in a direction substantially perpendicular to the substrate without applying a voltage. A vertical alignment nematic type VA mode in which this is driven by a thin film transistor has been proposed (see Patent Document 5). This VA mode not only has excellent display characteristics when viewed from the front, but also exhibits a wide viewing angle characteristic by applying a viewing angle compensation phase difference plate. In the VA mode, two negative uniaxial retardation plates having an optical axis in a direction perpendicular to the film surface are used on both sides of the liquid crystal cell, thereby obtaining an LCD having a wide viewing angle characteristic. It is also known that a wider viewing angle characteristic can be realized by further arranging a uniaxially oriented retardation plate having a positive refractive index anisotropy with an in-plane retardation value of 50 nm on this LCD. (Refer nonpatent literature 3).

  However, the use of two retardation plates as in Non-Patent Document 3 is not only an increase in the number of production steps and an increase in production cost, but also a decrease in yield because a large number of films are bonded together. However, there is a problem that the increase in thickness is disadvantageous for making the LCD thinner. In addition, since the adhesive layer is interposed in the lamination of the stretched film, the adhesive layer contracts due to a change in temperature and humidity, and product defects such as warpage and peeling between films may occur. As methods for improving these, a method of reducing the number of retardation plates (see Patent Document 6) and a method using a cholesteric liquid crystal layer (see Patent Documents 7 and 8) are disclosed. However, even in these methods, since it is necessary to bond a plurality of films, improvement has been insufficient in terms of thinning, reduction in the number of manufacturing steps and production cost.

  On the other hand, optical compensation films have been developed for TN LCDs. However, as demand for liquid crystal televisions increases in recent years, there is a problem in response speed, such as tailing and afterimage phenomenon. Is being pointed out. Therefore, attention has been focused on the OCB mode (or bend mode), which is characterized by a high response speed. However, it is difficult to obtain a wide viewing angle characteristic in the OCB mode, and it is necessary to use an optical compensation film. For example, in the inventions described in Patent Documents 9 and 10, an optical compensation film having a layer made of a liquid crystal compound is applied to an OCB type LCD. However, it has been difficult to obtain an LCD having good viewing angle characteristics only by controlling conventionally known optical parameters as described in these documents.

Furthermore, in any of the above display mode liquid crystal display devices, light leakage (light leakage) from the oblique direction of the polarizing plate during black display is not completely suppressed in the visible light region, and the viewing angle is sufficiently large. There was a problem of not expanding. More importantly, it is difficult to completely compensate for light leakage at all wavelengths of visible light with respect to the incident light in the oblique direction of the black display polarizing plate. May occur. In addition, a method of preventing light leakage by controlling the wavelength dispersion of retardation of a retardation plate has been proposed (see Patent Document 11), but in-plane retardation wavelength dispersion and thickness direction retardation are proposed. The difference from chromatic dispersion is not considered, and there is a problem that the effect of suppressing light leakage as described above is insufficient. That is, in the polymer film as described above, the wavelength dispersion value (ΔRe) of retardation in the in-plane direction (in-plane retardation) and the wavelength dispersion value of retardation in the film thickness direction (ΔRth) have the same sign value. Therefore, there is a limit to the optical compensation method or compensation. Therefore, there is a need for a method for independently and freely controlling the wavelength dependence of each of these retardations.
Japanese Unexamined Patent Publication No. 2003-236915 (page 3-4, FIG. 1) JP-A-9-95538 JP-A-9-95544 (page 4-7) JP-A-9-95557 (page 4-8) Japanese Patent Laid-Open No. 2-176625 JP-A-11-95208 JP 2003-15134 A JP-A-11-95208 JP-A-9-212444 JP 11-316378 A Japanese Patent Laid-Open No. 2002-221622 Macromolecular Chem., 1971, 143, p. 105 Journal of the Textile Machinery Society, 1981, 34, p. 57-61 SID (Society for Information Display) '97 DIGEST (p. 845-848)

  However, in order to obtain an image display device that can sufficiently satisfy the wavelength dependence associated with the wide viewing angle, it is essential to control the birefringence of the polymer film used in the image display device. Only mechanical measures such as tenter stretching in conventional solution casting and stretching after melt casting have limitations. In addition, the solution casting method can produce a film having excellent optical isotropy compared with melt casting, but has birefringence control that has optical compensation enough to satisfy the wavelength dependency. No method has been proposed. On the other hand, regarding the method for preparing a polymer solution used for solution casting, a proposal for improving the solubility has been made, but in addition to improving the solubility, the preparation method from the viewpoint of optical properties such as birefringence when used as a film. There are few examples that have been examined.

  Therefore, the present invention has been made in view of the above problems, and in order to obtain an image display device excellent in wavelength dependency accompanying a wide viewing angle, the primary structure of the polymer main chain and the side chain, and the main chain And the polymer solution with controlled retardation by examining the relationship between the film and the side chain in the film and the relationship between the preparation method of the polymer solution used in the solution casting method and the birefringence control of the film It is an object of the present invention to provide a polarizing plate using the polymer film.

  In order to achieve the above object, the polymer film of the present invention has an in-plane retardation value Re (n) and a thickness direction retardation value Rth (n) when the measurement wavelength is n (unit: nm). In this case, one of ΔRe obtained by Re (700) −Re (400) and ΔRth obtained by Rth (700) −Rth (400) is a positive value, and the other is a negative value. It is configured as a feature.

  The polymer film may be a multilayer structure in which a plurality of film parts are bonded together with an adhesive or the like, or an optically anisotropic layer coated on a film part of a single layer structure. . However, it is more preferable that the polymer film has a single layer structure.

  The ΔRth preferably satisfies 10 nm ≦ | ΔRth | ≦ 1000 nm, and ΔRe is preferably a negative value. Moreover, it is preferable that the polymer as a main component of a polymer film is a cellulose acylate, and it is more preferable that this cellulose acylate has an acyl group substitution degree of 2.87 or more.

  As the retardation plate of a liquid crystal display device, wherein the polymer film includes a liquid crystal cell provided between a pair of alignment films and a retardation plate provided on the anti-liquid crystal cell side of the alignment film. It is preferable to be used. The display mode of the liquid crystal display device is more preferably an IPS mode, an OCB mode, or a VA mode.

  Furthermore, the present invention includes a polarizing plate having a protective film on both sides of the polarizing film, wherein at least one of the protective films is the polymer film.

  Furthermore, the present invention relates to a method for preparing a polymer solution from a mixture containing a polymer and a solvent, and a swelling step of swelling the polymer with the solvent at a temperature of −10 ° C. to 50 ° C., and the swelling step A cooling step for cooling the mixture after heating, and a heating step for heating the mixture after the cooling step, wherein the temperature by the cooling step is lower than the temperature in the swelling step, and -100 ° C or more and -10 ° C The method includes a method for preparing a polymer solution characterized in that the temperature in the heating step is 0 ° C. or higher and 57 ° C. or lower.

  In the method for preparing the polymer solution, the mixture is preferably cooled under pressure in the cooling step, and the main component of the solvent is preferably a chlorinated organic solvent. The main component of the polymer is preferably cellulose acylate, and the cellulose acylate more preferably has an acyl group substitution degree of 2.87 or more.

  As a result of intensive studies, the present inventors have been able to obtain a polymer film having a sign in which the wavelength dependency of the in-plane retardation value and the wavelength dependency of the thickness direction retardation value are different. That is, since the polymer film of the present invention is excellent in the wavelength dependency of the optical compensation property accompanying the wide viewing angle, it is suitably used for an image display device as a polarizing plate protective film or a retardation plate. In addition, according to the method for preparing a polymer solution of the present invention, the solubility of the polymer in a solvent can be improved, and when the polymer solution is used to form a solution, the main chain and the side chain of the polymer can be aligned in a predetermined state. Therefore, a polymer film having a predetermined birefringence can be obtained.

  Furthermore, when a polymer film is produced from the polymer solution by solution casting, a balance between the wavelength dependency of the in-plane retardation value and the wavelength dependency of the thickness direction retardation value is further increased by adding a stretching process. It becomes possible to control. Therefore, by appropriately selecting the type of polymer and the film forming conditions, each wavelength dispersion of the in-plane retardation of the film and the retardation in the thickness direction can be controlled independently, and the optical dispersion according to the application. The optimum value can be obtained, and the viewing angle compensation in the black state of the liquid crystal cell can be made possible at almost all wavelengths. As a result, in the liquid crystal display device using the polymer film according to the present invention, light leakage in an oblique direction during black display is reduced, and the viewing angle contrast is remarkably improved. In addition, since this liquid crystal display device can suppress light leakage in an oblique direction during black display in almost all visible light wavelength regions, color misregistration during black display depending on the viewing angle, which has been a problem in the past, has occurred. Greatly improved.

Hereinafter, embodiments of the present invention will be described in detail. First, in the present invention, the in-plane retardation value (Re) and the thickness direction retardation value (Rth) are calculated by the following equations (1) and (2), respectively. In the following formulas (1) and (2), nx is the refractive index in the slow axis direction in the polymer film plane, ny is the refractive index in the fast axis direction in the polymer film plane, and nz Is the refractive index in the direction perpendicular to the polymer film surface, and d is the thickness (unit: nm) of the polymer film.
Re = (nx−ny) × d (1)
Rth = {(nx + ny) / 2−nz} × d (2)

  In this embodiment, the retardation value is determined by the He-Ne laser using an ellipsometer (model: M-150, manufactured by JASCO Corporation) after leaving the polymer film at 25 ° C. and 60% relative humidity for 24 hours. It is a value measured using a light source. Moreover, when measuring a polymer film having a high retardation exceeding 100 nm, a value measured using various commercially available automatic birefringence meters (for example, model KOBRA-21, manufactured by Oji Scientific Instruments). Can be obtained by a known calculation method.

  In the following description, when the measurement wavelength is n (unit: nm), the plane direction retardation value is Re (n), and the thickness direction retardation value is Rth (n). The in-plane retardation chromatic dispersion value obtained by -Re (400) is represented by ΔRe, and the thickness direction retardation chromatic dispersion value obtained by Rth (700) -Rth (400) is represented by ΔRth. In the present embodiment, the ΔRe and ΔRth are obtained by allowing the polymer film to stand at 25 ° C. and a relative humidity of 60% for 24 hours, and then setting the measurement wavelength to 400 nm and 700 nm using the Xe light source with the ellipsometer. Calculated based on the formula.

  In the polymer film of the present invention, either ΔRe or ΔRth has a positive value and the other has a negative value. Therefore, in the conventional polymer film, since the sign of Re value and Rth value has the same sign, when this is used as a phase difference plate, the wavelength dependency thereof cannot be controlled independently. When this polymer film is used alone or in combination with another polymer film as a retardation plate, the wavelength dependence and thickness of the retardation value Re in the plane direction as the resulting retardation plate The wavelength dependence of the direction retardation value Rth can be independently controlled. Therefore, the obtained retardation plate has the advantage of more completely compensating for the wavelength dependence of retardation accompanying the change in viewing angle. Therefore, the polymer film of the present invention can be suitably used as at least a part of a retardation film that is used alone as a retardation film, or a combination of a plurality of these films or a combination of other films. .

  By the way, in order to more completely compensate the phase difference, it is preferable that | ΔRth | is larger. Therefore, when a film having a small | ΔRth | is used, a plurality of layers are stacked. Need to increase. When the number of films to be laminated increases, the thickness increases, so when this is used as a retardation plate in a display device, the thickness of the display device also increases, and misalignment occurs due to mutual positional deviation in the lamination. Sometimes.

  Therefore, in the film according to the present embodiment, | ΔRth | is 10 nm or more in addition to the above conditions of ΔRe and ΔRth. Thereby, since the number of film lamination required for performing predetermined retardation compensation can be reduced as compared with the conventional film, it is possible to reduce the thickness of the retardation plate and to suppress the occurrence of color misregistration due to the lamination. . The value of | ΔRth | is more preferably 10 nm to 1000 nm, still more preferably 12 nm to 500 nm, and particularly preferably 15 nm to 100 nm. In addition, it is substantially difficult to make the value of | ΔRth |

  Further, | ΔRe | is preferably 10 nm or more and 1000 nm or less. When | ΔRe | is larger than 1000 nm, the film is not preferable because it is easily affected by external factors such as external stress and humidity. When | ΔRe | is less than 10 nm, complete phase difference compensation is performed. However, as in the case of | ΔRth |, there is a problem in terms of the thickness of the retardation plate and color misregistration. This | ΔRe | is more preferably 10 nm or more and 500 nm or less, and further preferably 10 nm or more and 200 nm or less. In some cases, the thickness is preferably 10 nm or more and 150 nm or less, and particularly preferably 10 nm or more and 100 nm or less. In the film of the present invention, ΔRe is a negative value and ΔRth is a positive value.

  Such a polymer film of the present invention can be used as an optical compensation film, and the viewing angle contrast of a liquid crystal display device, particularly a VA mode, OCB mode, or IPS mode liquid crystal display device, and a color depending on the viewing angle. Contributes to the reduction of displacement. The obtained optical compensation film may be used in a state where it is arranged between the liquid crystal cell and the polarizing plate on the viewer side, or between the liquid crystal cell and the polarizing plate on the back side, or both. It may be used in a distributed manner. For example, it can be incorporated into the LCD as an independent member, or can be incorporated into the LCD as a transparent polarizing plate protective film imparted with optical characteristics, that is, as a member of a polarizing plate.

  In the present invention, the polymer film is preferably transparent, and the main component of the polymer film is polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, norbornene resin, cellulose ester, etc. whose primary structure is controlled. Among them, cellulose ester is particularly preferable. As this cellulose ester, 1 type may be used independently and 2 or more types of different cellulose esters may be mixed and used. However, among them, cellulose acylate is preferable. In addition, the said main component means 55 mass% or more of a polymer component, Preferably it is 70 mass% or more, More preferably, it is 80 mass% or more.

Cellulose is composed of glucose units linked by β-1,4, and these glucose units have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The acyl group substitution degree in cellulose acylate means the ratio of cellulose esterified at each of the 2nd, 3rd and 6th positions. Therefore, when each hydroxyl group is 100% esterified, the degree of substitution is 1, and when all hydroxyl groups are 100% esterified, the degree of substitution is 3. As the cellulose acylate in the present invention, the degree of substitution of the hydroxyl group of cellulose preferably satisfies the following condition (I), and more preferably satisfies the conditions of (II) and (III) in addition to this. . In the following conditions (I), (II), and (III), SA represents the degree of substitution with an acetyl group, and SB represents the degree of substitution with an acyl group having 3 to 22 carbon atoms.
(I) 2.87 ≦ SA + SB ≦ 3.00
(II) 0.0 ≦ SA ≦ 3.0
(III) 0.0 ≦ SB ≦ 3.0

  The total substitution degree SA + SB of hydroxyl groups with SA and SB is more preferably 2.87 or more and 2.96 or less, further preferably 2.88 or more and 2.95 or less, and in some cases 2.90 or more. Particularly preferred is 2.95 or less.

  X of the acyl group having 3 to 22 carbon atoms (—COX) satisfying the SB is not particularly limited, and X may be an aliphatic group (—R) or an aryl group (—Ar). Therefore, examples of such cellulose acylate may be an alkylcarbonyl ester, an alkenylcarbonyl ester, an aromatic carbonyl ester, an aromatic alkylcarbonyl ester, or the like, or an ester having a substituent. Preferred examples of the acyl group having 3 to 22 carbon atoms include propionyl, butanoyl, keptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, And cyclohexanecarbonyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl group, and the like. Among these, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are more preferable.

  The preferred degree of polymerization of the cellulose ester in the present invention is such that the viscosity average degree of polymerization is 200 to 700, more preferably 250 to 550, still more preferably 250 to 400, and particularly preferably 250 to 350. The average degree of polymerization can be measured, for example, by the intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, 1962, Vol. 18, No. 1, p. 105-120). Are described in detail.

  When cellulose ester is used in the present invention, the raw material form is preferably particles. And 90 mass% or more of the particle | grains to be used are preferable that it is a particle diameter of 0.5-5 mm, and it is more preferable that 50 mass% or more of the particle | grains to be used is a particle diameter of 1-4 mm. Furthermore, it is preferable that the particles have a shape as close to a sphere as possible.

  By the way, it is generally known that the cellulose ester contains water, and its water content is 2.5 to 5% by mass. Therefore, when a cellulose ester is used in the present invention, its water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less. . In order to obtain this moisture content, it is necessary to carry out a drying treatment, but the method is not particularly limited as long as the cellulose ester is not deteriorated.

  Further, in the present invention, the raw material cotton and the synthesis method of cellulose ester are those described in the Journal of the Invention Association (public technical number 2001-1745, published on March 15, 2001, p.7-12, Invention Association). Can be applied.

  In the polymer film of the present invention, the polymer can be other than cellulose ester. That is, any polymer can be used as long as the polymer or its precursor as a main component of the film can form a polymer solution by using a solvent. Examples thereof include various polyolefins such as polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, and polyamide.

  Next, the polymer solution preparation method of the present invention for producing the polymer film will be described below.

  With respect to the solvent, in the present invention, a predetermined polymer is dissolved and can be formed by solution casting, and when it is made into a polymer film, various mechanical strength, elastic modulus, heat resistance, etc. Although not particularly limited as long as the characteristics can be satisfied, a chlorinated organic solvent is more preferable, and this chlorinated organic solvent is particularly preferable when a cellulose ester is used as a polymer main component. Preferred examples of the chlorinated organic solvent include dichloromethane and chloroform, with dichloromethane being particularly preferred. However, an organic solvent other than the chlorine-based organic solvent, that is, a non-chlorine-based organic solvent may be mixed with the chlorine-based organic solvent. Are preferably used.

  Non-chlorine organic solvents used in combination with chlorinated organic solvents are described below. That is, preferred non-chlorine organic solvents are esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms. These esters, ketones, ethers and alcohols may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a solvent. It may have other functional groups such as Also in the case of such a solvent having two or more types of functional groups, the number of carbon atoms is preferably 3 to 12. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The alcohol used in combination with the chlorinated organic solvent may be a linear structure, a branched structure, or a cyclic structure, and among them, saturated aliphatic hydrocarbons. Preferably there is. The alcohol may be any of primary to tertiary. Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol, and fluorine. Series alcohols can also be used. Examples of the fluorinated alcohol include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.

  In the present invention, when cellulose ester is used as a polymer, the following can be exemplified as a combination of a chlorinated organic solvent and a non-chlorinated organic solvent in the polymer solution. However, the present invention is not limited to these. In the following description of the combination, each ratio shown in parentheses indicates a blending part by mass of each solvent.

・ Dichloromethane / methanol / ethanol / butanol (75/10/5/5/5)
・ Dichloromethane / acetone / methanol / propanol (80/10/5/5)
・ Dichloromethane / methanol / butanol / cyclohexane (75/10/5/5/5)
・ Dichloromethane / methyl ethyl ketone / methanol / butanol (80/10/5/5)
・ Dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/10/5/7)
・ Dichloromethane / cyclopentanone / methanol / isopropanol (80/10/5/8)
・ Dichloromethane / methyl acetate / butanol (80/10/10)
・ Dichloromethane / cyclohexanone / methanol / hexane (70/20/5/5)
・ Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5)
・ Dichloromethane / 1, 3 dioxolane / methanol / ethanol (70/20/5/5)
・ Dichloromethane / dioxane / acetone / methanol / ethanol (60/20/10/5/5)
・ Dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5)
・ Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (70/10/10/5/5)
・ Dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5)
・ Dichloromethane / methyl acetoacetate / methanol / ethanol (65/20/10/5)
・ Dichloromethane / cyclopentanone / ethanol / butanol (65/20/10/5)

  Moreover, when preparing the solution of the cellulose ester which is a polymer preferably used by this invention, a non-chlorine-type organic solvent can also be made into a main solvent depending on the case. In this case, the non-chlorine organic solvent is preferably an ester, ketone or ether having 3 to 12 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent, such as an alcoholic hydroxyl group. It may have a functional group of Also in the case of such a main solvent having two or more types of functional groups, the number of carbon atoms is preferably 3-12. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The non-chlorine organic solvent as the above main solvent is selected as appropriate, and is preferably as follows. That is, the preferred solvent of the cellulose ester of the present invention is a mixed solvent of three or more different from each other, and the first solvent is selected from methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, and dioxane. At least one kind or a mixture thereof, and the second solvent is selected from ketones having 4 to 7 carbon atoms or acetoacetate, and the third solvent is alcohol having 1 to 10 carbon atoms or It is selected from hydrocarbons, and more preferably an alcohol having 1 to 8 carbon atoms. Note that when the first solvent is a mixed liquid of two or more kinds of solvents, the second solvent may be omitted. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, or methyl acetyl acetate. It may be.

  The alcohol as the third solvent may have a linear structure, a branched structure, or a cyclic structure, and among them, a saturated aliphatic hydrocarbon is preferable. The alcohol may be any of primary to tertiary. Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol, and fluorine. Series alcohols can also be used. Examples of the fluorinated alcohol include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene. These alcohols and hydrocarbons as the third solvent may be used alone or in combination of two or more, and are not particularly limited. As the third solvent, preferred specific compounds include alcohol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane, Are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol.

  In the mixed solvent containing the above three types of components, the first solvent is contained in a proportion of 20 to 95% by mass, the second solvent is contained in a proportion of 2 to 60% by mass, and the third solvent is contained in a proportion of 2 to 30% by mass. Preferably, the first solvent is 30 to 90% by mass, the second solvent is 3 to 50% by mass, and the third alcohol is preferably 3 to 25% by mass. In particular, it is preferable that the first solvent is 30 to 90% by mass, the second solvent is 3 to 30% by mass, and the third solvent is alcohol and 3 to 15% by mass. In addition, when the first solvent is a mixed solution and the second solvent is not used, the first solvent is preferably contained in a ratio of 20 to 90% by mass and the third solvent in a ratio of 5 to 30% by mass, Furthermore, it is preferable that a 1st solvent is 30-86 mass%, and also a 3rd solvent is contained 7-25 mass%. The non-chlorine organic solvent used in the present invention described above is more specifically described in pages 12 to 16 in the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in detail and can be applied to the present invention.

    In the method for preparing a polymer solution of the present invention, the polymer is preferably dissolved in an organic solvent in an amount of 10 to 50% by mass, more preferably 13 to 40% by mass, and particularly preferably 15 to 30% by mass. . These concentration methods may be blended so as to have a predetermined concentration at the stage of mixing, and after preparing a low concentration solution (for example, 9 to 14% by mass) in advance, a predetermined concentration method may be used. The concentration may be adjusted. Furthermore, after preparing a high concentration polymer solution in advance, it may be adjusted to a predetermined concentration by adding various additives, solvents and the like.

  In the preparation of the polymer solution described below, various additives depending on the application can be added at a predetermined timing, and they may be solid or oily. Examples of the additive include plasticizers, modifiers, ultraviolet absorbers, ultraviolet stabilizers, optical anisotropy control agents, fine particles, release agents, infrared absorbers, and the like. Moreover, it does not specifically limit in these melting | fusing point and boiling point. For example, UV absorbers, plasticizers, and the like may be used in combination with those having a melting point of 20 ° C. or lower and those having a melting point of 20 ° C. or higher. Such examples are described in JP-A-2001-151901, etc. Yes. Furthermore, the infrared absorber is described in, for example, Japanese Patent Application Laid-Open No. 2001-194522, and can be applied to the present invention. The addition timing of these additives may be any timing in the polymer solution preparation step, but these addition operations may be performed at the end of the polymer solution preparation step. Furthermore, the amount of addition is not particularly limited. In addition, when the polymer film is formed from multiple layers, the type and amount of additives in each layer may be different, and a well-known technique described in, for example, JP-A-2001-151902 is applied to the present invention. be able to. As such an additive, those described in the Journal of the Invention Association (Technology No. 2001-1745, published on March 15, 2001, p.16-22, Invention Association) are preferably used.

The retardation controlling agent as the optical anisotropy controlling agent will be described in detail below. In the present invention, a retardation control agent may be added to the polymer film, and this retardation control agent is a rod-shaped compound having at least two aromatic rings, and is represented by the following general formula (1) The compound represented by these is preferable. In General Formula (1), Ar ¹ and Ar ² are each independently an aromatic group, and L ¹ is an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, or a combination thereof. A divalent linking group selected from the group consisting of
Formula (1): Ar ¹ -L ¹ -Ar ²

  The aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group. An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, and more preferably a 5-membered ring or a 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable. Examples of aromatic hetero rings include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine Rings, pyridazine rings, pyrimidine rings, pyrazine rings, and 1,3,5-triazine rings are included. As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of substituents for substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, alkylamino groups (eg, methylamino, ethylamino) , Butylamino, dimethylamino), nitro, sulfo, carbamoyl, alkylcarbamoyl groups (eg, N-methylcarbamoyl, N-ethylcarbamoyl, N, N-dimethylcarbamoyl), sulfamoyl, alkylsulfamoyl groups (eg, N- Methylsulfamoyl, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), ureido, alkylureido groups (eg, N-methylureido, N, N-dimethylureido, N, N, N′-trimethyl) Ureido), alkyl groups (eg, methyl, ethyl, propyl, butyl, pentyl) Heptyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, cyclopentyl), alkenyl groups (eg, vinyl, allyl, hexenyl), alkynyl groups (eg, ethynyl, butynyl), acyl groups (eg, formyl, acetyl, Butyryl, hexanoyl, lauryl), acyloxy groups (eg, acetoxy, butyryloxy, hexanoyloxy, lauryloxy), alkoxy groups (eg, methoxy, ethoxy, propoxy, butoxy, pentyloxy, heptyloxy, octyloxy), aryloxy groups (Eg, phenoxy), alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, heptyloxycarbonyl), aryloxycar Nyl group (eg, phenoxycarbonyl), alkoxycarbonylamino group (eg, butoxycarbonylamino, hexyloxycarbonylamino), alkylthio group (eg, methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio, octylthio), arylthio group (eg, , Phenylthio), alkylsulfonyl groups (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl), amide groups (eg, acetamido, butyramide, hexylamide, laurylamide) and non- Aromatic heterocyclic groups (eg, morpholyl, pyrazinyl) are included.

  Substituents of substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms, cyano, carboxyl, hydroxyl, amino, alkyl-substituted amino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthios. And groups and alkyl groups are preferred. The alkyl part and alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl, carboxyl, cyano, amino, alkylamino group, nitro, sulfo, carbamoyl, alkylcarbamoyl group, sulfamoyl, alkylsulfamoyl group, ureido, alkylureido Group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, alkylsulfonyl group, amide group and non-aromatic An aromatic heterocyclic group is included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, hydroxyl, amino, alkylamino group, acyl group, acyloxy group, acylamino group, alkoxycarbonyl group and alkoxy group are preferable.

L ¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO— and a combination thereof. The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group. The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, and most preferably 1-6. It is.

  The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure. The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene or ethynylene). The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

The example of the bivalent coupling group which consists of a combination is shown.
L-1: —O—CO-alkylene group —CO—O—
L-2: -CO-O-alkylene group -O-CO-
L-3: —O—CO—alkenylene group —CO—O—
L-4: -CO-O-alkenylene group -O-CO-
L-5: -O-CO-alkynylene group -CO-O-
L-6: -CO-O-alkynylene group -O-CO-
L-7: -O-CO-arylene group -CO-O-
L-8: -CO-O-arylene group -O-CO-
L-9: -O-CO-arylene group -CO-O-
L-10: -CO-O-arylene group -O-CO-

In the molecular structure of the general formula (1), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more. As the rod-like compound, a compound represented by the following formula (2) is more preferable. In the general formula (2), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ¹ and Ar ^{2 in} the general formula (1).
Formula ^{(2): Ar 1 -L 2} -X-L 3 -Ar 2

In the general formula (2), L ² and L ³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO— and a group consisting of a combination thereof. The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure. The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene or Most preferred is ethylene). L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the general formula (2), X is 1,4-cyclohexylene, vinylene or ethynylene.

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

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

  As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type. Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate. In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

  Preferred compounds that can be used as other retardation control agents are shown below.

  As the retardation control agent, it is preferable to use two or more kinds of rod-shaped compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution. The rod-like compound can be synthesized with reference to methods described in literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989), J. Am. Am. Chem. Soc. 113, p. 1349 (1991), p. 118, p. 5346 (1996), p. 92, p. 1582 (1970). Org. Chem. 40, 420 pages (1975), Tetrahedron, Vol. 48, No. 16, page 3437 (1992).

  A wavelength dispersion adjusting agent may be added to the polymer film of the present invention, and the wavelength dispersion adjusting agent is preferably one that does not evaporate in the course of heat treatment such as dope casting or film drying. From the viewpoint of volatility, the wavelength dispersion adjusting agent preferably has a molecular weight of 250 to 1000, more preferably 260 to 800, still more preferably 270 to 800, and particularly preferably 300 to 800. Within these molecular weight ranges, a monomer structure may be used, or an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.

  Specific examples of the wavelength dispersion adjusting agent include, for example, benzotriazole compounds, benzophenone compounds, cyano group-containing compounds, oxybenzophenone compounds, salicylic acid ester compounds, nickel complex salts, and the like. It is not limited to only compounds.

An example of a preferable wavelength dispersion adjusting agent is a compound represented by the following general formula (3). In this general formula (3), Q ¹ represents a nitrogen-containing aromatic heterocycle, and Q ² represents an aromatic ring.
Formula ^{(3) Q 1} -Q 2 -OH

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

The aromatic ring represented by Q ² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring. The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (such as a benzene ring or a naphthalene ring), and more preferably 6 to 20 carbon atoms. An aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms, and more preferably a benzene ring. The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the aromatic heterocycle include, for example, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, Examples thereof include isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline. Q ² is preferably an aromatic hydrocarbon ring, more preferably a naphthalene ring or a benzene ring, and particularly preferably a benzene ring.

Q ¹ and Q ² may each further have a substituent, and a substituent selected from the following substituent T is preferred.

  Substituent T: alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n- Octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 2 carbon atoms). For example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 2 carbon atoms). 8 such as propargyl and 3-pentynyl), an aryl group (preferably having 6 to 30 carbon atoms, more preferred) Has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, etc.), a substituted or unsubstituted amino group (preferably having 0 to 20 carbon atoms, More preferably, it has 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, and examples thereof include amino, methylamino, dimethylamino, diethylamino, dibenzylamino, and the like, and an alkoxy group (preferably having 1 to 1 carbon atoms). 20, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more preferably The number of carbon atoms is 6 to 16, particularly preferably 6 to 12, and examples thereof include phenyloxy and 2-naphthyloxy. An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, pivaloyl and the like), an alkoxycarbonyl group ( Preferably it has 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonyl, ethoxycarbonyl and the like, and an aryloxycarbonyl group (preferably having a carbon number). 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl, etc.), acyloxy group (preferably 2 to 20 carbon atoms, more preferably carbon 2 to 16, particularly preferably 2 to 10 carbon atoms. For example, acetoxy, benzoyloxy Examples include shi. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino), alkoxycarbonylamino group (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryloxycarbonylamino group (preferably having carbon number) 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino, and the like, and sulfonylamino groups (preferably 1 to 20 carbon atoms, more preferably Has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. And sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl and methylsulfamoyl). , Dimethylsulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as carbamoyl). , Methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, Ethylthio etc.), arylthio group (preferably Has 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably Has 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms). For example, ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms) More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, diethyl phosphoric acid amide, phenylphosphoric acid amide etc. are mentioned. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, piperidyl , Morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.) and a silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms). And examples thereof include trimethylsilyl and triphenylsilyl). These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

  Among the compounds represented by the general formula (3), a benzotriazole-based compound represented by the following general formula (3-A) is preferable.

In General Formula (3-A), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represent a hydrogen atom or a substituent.

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

R ² and R ⁴ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group or a halogen atom, more preferably a hydrogen atom or a carbon 1-12 alkyl group, particularly preferably a hydrogen atom or a methyl group, most preferably Is a hydrogen atom.

R ⁵ and R ⁸ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group or a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group or a halogen atom, more preferably a hydrogen atom or a carbon 1-12 alkyl group, particularly preferably a hydrogen atom or a methyl group, most preferably Is a hydrogen atom.

R ⁶ and R ⁷ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group or a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, or a halogen atom, more preferably a hydrogen atom or a halogen atom, and particularly preferably a hydrogen atom or a chlorine atom.

  Among the benzotriazole compounds represented by the general formula (3-A), compounds represented by the following general formula (3-B) are more preferable.

In the formula, R ¹ , R ³ , R ⁶ and R ⁷ have the same meanings as those in the general formula (3-A), and preferred ranges thereof are also the same.

  Although the specific example of a compound represented by General formula (3) below is given, this invention is not limited to the following specific example at all.

  Among the benzotriazole compounds exemplified in the above examples, when the polymer film of the present invention was produced without containing a compound having a molecular weight of 320 or less, it was confirmed that it was advantageous in terms of retention.

  Another preferred example of the wavelength dispersion adjusting agent is a compound represented by the following general formula (4).

In the formula, Q ¹¹ and Q ¹² each independently represents an aromatic ring. X represents NR (R represents a hydrogen atom or a substituent), an oxygen atom, or a sulfur atom.

The aromatic ring represented by Q ¹¹ and Q ¹² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring. The aromatic hydrocarbon ring represented by Q ¹¹ and Q ¹² is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring, a naphthalene ring, etc.), More preferably, it is a C6-C20 aromatic hydrocarbon ring, More preferably, it is a C6-C12 aromatic hydrocarbon ring, More preferably, it is a benzene ring. The aromatic heterocycle represented by Q ¹¹ and Q ¹² is preferably an aromatic heterocycle containing at least one of any one of an oxygen atom, a nitrogen atom and a sulfur atom. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, Examples include quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzothiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline. Q ¹¹ and Q ¹² are preferably aromatic hydrocarbon rings, more preferably aromatic hydrocarbon rings having 6 to 10 carbon atoms, and still more preferably substituted or unsubstituted benzene rings. Q ¹¹ and Q ¹² may further have a substituent, and the above-described substituent T is preferable. However, the substituent does not include a carboxylic acid, a sulfonic acid, or a quaternary ammonium salt. Further, if possible, substituents may be linked to form a ring structure.

  X represents NR (R represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied), an oxygen atom or a sulfur atom, and X is preferably NR (as R Preferably they are an acyl group and a sulfonyl group, and these substituents may be further substituted), or O, and particularly preferably O.

  Among the compounds represented by the general formula (4), a benzophenone compound represented by the following general formula (4-A) is more preferable.

In the formula, R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ each independently represent a hydrogen atom or a substituent.

R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ each independently represent a hydrogen atom or a substituent, and the above-mentioned substituent T is applied as the substituent. it can. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹¹ , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁸ and R ¹⁹ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, An aryloxy group, a hydroxy group or a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group or a halogen atom, and still more preferably a hydrogen atom or a carbon 1-12 alkyl group. And particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

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

R ¹⁷ is preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, aryloxy group, hydroxy group or halogen atom, more preferably a hydrogen atom or carbon number. An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, or a hydroxy group, more preferably a hydrogen atom or 1 to 20 carbon atoms. Alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably a methyl group), particularly preferably a methyl group or a hydrogen atom.

  Among the benzophenone compounds represented by the general formula (4-A), compounds represented by the following general formula (4-B) are more preferable.

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

R ¹⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group, and the substituent is the above-described substituent T Is applicable. R ¹⁰ is preferably a substituted or unsubstituted alkyl group, more preferably a substituted or unsubstituted alkyl group having 5 to 20 carbon atoms, and still more preferably a substituted or unsubstituted alkyl group having 5 to 12 carbon atoms. Group (including n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substituent having 6 to 12 carbon atoms. Or it is an unsubstituted alkyl group (2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group).

  The compound represented by the general formula (4) can be synthesized by a known method described in JP-A-11-12219. Although the specific example of a compound represented by General formula (4) below is given, this invention is not limited to the following specific example at all.

  Another preferred example of the wavelength dispersion adjusting agent is a compound represented by the following general formula (5).

In the formula, Q ²¹ and Q ²² each independently represent an aromatic ring. X ¹ and X ^{2 each} represent a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle.

The aromatic ring represented by Q ²¹ and Q ²² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring. The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (such as a benzene ring or a naphthalene ring), and more preferably 6 to 20 carbon atoms. Aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms, and still more preferably a benzene ring. The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.

Q ²¹ and Q ²² are preferably aromatic hydrocarbon rings, and more preferably benzene rings. Q ²¹ and Q ²² may further have a substituent, and the substituent T described above is preferable as the substituent.

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

X ¹ and X ² are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group or an aromatic heterocyclic ring, more preferably a cyano group, a carbonyl group, a sulfonyl group or An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR (R is an alkyl group having 1 to 20 carbon atoms, 6 carbon atoms). ~ 12 aryl groups and combinations thereof.

  Among the compounds represented by the general formula (5), compounds represented by the following general formula (5-A) are preferable.

In the formula, R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ and R ³⁰ each independently represent a hydrogen atom or a substituent. X ¹ and X ² have the same meanings as those in formula (5), and preferred ranges are also the same.

R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ and R ³⁰ each independently represents a hydrogen atom or a substituent, and the substituent is the above-described substituent. T is applicable. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ²¹ , R ²² , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁹ and R ³⁰ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, An alkoxy group, an aryloxy group, a hydroxy group or a halogen atom, more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group or a halogen atom, still more preferably a hydrogen atom or carbon 1-12. An alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ²³ and R ²⁸ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group or a halogen atom, more preferably a hydrogen atom. , An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, or a hydroxy group, more preferably a hydrogen atom or carbon number. It is a 1-12 alkyl group or a C1-C12 alkoxy group, Most preferably, it is a hydrogen atom.

  Among the compounds represented by the general formula (5-A), compounds having a cyano group represented by the following general formula (5-B) are preferable.

R ²³ and R ²⁸ have the same meanings as those in formula (5-A), and preferred ranges are also the same. X ³ represents a hydrogen atom or a substituent.

X ³ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with another substituent. X ³ is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group or an aromatic heterocycle, more preferably a cyano group, a carbonyl group, a sulfonyl group or an aromatic heterocycle. A ring, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (-C (= O) OR (where R is an alkyl group having 1 to 20 carbon atoms, 6 to 12 carbon atoms). Aryl groups and combinations thereof).

  Among the compounds represented by the general formula (5-B), compounds represented by the following general formula (5-C) are more preferable.

In the formula, R ²³ and R ²⁸ have the same meanings as those in formula (5-A), and preferred ranges thereof are also the same. R ³¹ represents an alkyl group having 1 to 20 carbon atoms.

R ³¹ is preferably an alkyl group having 2 to 12 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms, and still more preferably a carbon number when R ²³ and R ²⁸ are both hydrogen. 6 to 12 alkyl groups, particularly preferably n-octyl group, tert-octyl group, 2-ethylhexyl group, n-decyl group and n-dodecyl group, most preferably 2-ethylhexyl. It is a group.

Preferably, when R ²³ and R ²⁸ are other than hydrogen as R ³¹ , the compound represented by formula (5-C) has a molecular weight of 300 or more and an alkyl group having 20 or less carbon atoms. preferable.

  The compound represented by the general formula (5) of the present invention can be synthesized by a method described in Journal of American Chemical Society 63, 3452 (1941).

  Although the specific example of a compound represented by General formula (5) below is given, this invention is not limited to the following specific example at all.

  When various additives are used, the polymer solution contains 0.1 to 20% by mass of at least one liquid or solid plasticizer with respect to the polymer, and / or at least one liquid or solid plasticizer. 0.001 to 5% by mass of an ultraviolet absorber with respect to the polymer, and / or a fine particle powder having an average particle diameter of 5 to 3000 nm and at least one kind of solid is 0.001 with respect to the polymer. -5% by mass and / or 0.001-2% by mass of at least one fluorosurfactant in the polymer and / or at least one release agent in the polymer. 0.0001-2% by mass with respect to the polymer and / or 0.0001-2% by mass of at least one kind of deterioration inhibitor with respect to the polymer, and / or Contains 0.1 to 15% by mass of at least one optical anisotropy control agent with respect to the polymer, and / or 0.1 to 5% by mass of at least one infrared absorber with respect to the polymer. It is preferable to contain.

  Next, a method for preparing a polymer solution using the above polymer and solvent will be described below with reference to the drawings. In the present embodiment, cellulose acylate having acyl group substitution degrees of 2.91 and 2.92 is used as the polymer, and a mixed solvent of dichloromethane, methanol, and butanol is used as the solvent. Is not limited to the following embodiments.

  FIG. 1 is a process diagram of polymer solution preparation according to the first embodiment of the present invention, and FIG. 2 is a schematic diagram of a polymer solution preparation apparatus. The polymer solution preparation step in the present embodiment includes a swelling step 11, a first cooling step 12, a heating step 13, a pressure heating step 16, and a second cooling step 17, and if necessary, a stirring step 21 and a filtration step. At least one of 22 is performed after the heating operation.

  The swelling step 11 is for mixing the polymer and the solvent and swelling the polymer with this solvent. In the first cooling step 12, the mixture that has undergone the swelling step 11 is cooled to a predetermined temperature by the cooling means. In the heating step, the temperature of the mixture is raised by a heating means to a predetermined temperature. In the pressurizing and heating step 16, the mixture is heated under pressure, and then, in the second cooling step 17, the mixture is cooled again to a predetermined temperature to obtain a polymer solution 23. In the agitation step 21, the mixture that has undergone the heating step 13 is agitated to make the concentration or dispersion uniform, and in the filtration step 22, solids or gels having a predetermined size or more are removed by filtration. .

  And, as shown in FIG. 2, the polymer solution preparation apparatus 30 used in this embodiment includes a first tank 31 for swelling the polymer with a solvent, a first cooling unit 32 for cooling the mixture, A heating unit 35 for heating the mixture, a second tank 36 for stirring, first and second filters 37, 38, and a pressure heating unit 41 for heating the mixture under pressure; The second cooling unit 42 is connected to the casting apparatus 43 from the second cooling unit 42. In the present embodiment, a liquid feed pump such as a screw pump is appropriately provided in the liquid feed path, but the illustration is omitted here in order to avoid the complexity of the illustration. However, the present invention is not limited to the polymer solution adjusting device 30.

  The first tank 31 includes a stirrer 46, and a dissolver type eccentric stirrer is used in the present embodiment. The stirrer 46 is provided with an anchor type stirring blade 46b on a stirring shaft 46a driven by a motor (not shown). The motor includes a controller (not shown), and the rotation speed is controlled by this controller. The first tank 31 has a jacket 47 on its outer periphery, and a heat transfer medium 48 controlled to a predetermined temperature by a controller (not shown) is continuously flowed between the jacket 47 and the tank body 31a. . In the present embodiment, the heat transfer medium 51 is a circulation type that circulates between the controller and the jacket 47.

  As the heat transfer medium 51, various fluids such as water, various alcohols, nitrogen, air, brine, and chlorofluorocarbons can be used. Water and air are preferable from the viewpoint of cost and handleability. Moreover, when controlling to temperature lower than 0 degreeC, ethylene glycol, water, a brine, a Freon etc. are illustrated as a preferable thing, for example. In the present embodiment, the first tank 31 is provided with a pressurizing mechanism that makes the inside a predetermined pressure with nitrogen gas, thereby improving the swelling efficiency of the polymer. However, the present invention does not depend on the structure of the first tank 31 or the temperature control method, and may be anything as long as the mixture can be controlled to a predetermined temperature and the polymer can swell.

  The first cooling unit 32 and the heating unit 35 both have a temperature controller, and cool and heat the mixture containing the swollen polymer to a predetermined temperature, respectively. In the present embodiment, the first cooling unit 32 and the heating unit 35 are a screw pump provided with a jacket through which the heat transfer medium flows, and the temperature of the heat transfer medium is controlled by a temperature controller. The mixture is cooled and heated to a predetermined temperature. In addition, the 1st cooling part 32 has the pressure controller 32a, and controls the pressure of the 1st cooling part 32 so that it may become a predetermined value as needed.

  Similar to the first tank 31, the second tank 36 includes a tank body 36a and a jacket 52, and also includes a stirrer 53 having a stirring shaft 53a and a stirring blade 53b. The temperature of the mixed liquid in the tank body 36 a is controlled by controlling the temperature of the heat transfer medium 55 flowing through the jacket 52 by a controller (not shown), and the concentration or dispersion concentration is controlled by the rotation of the stirrer 53. Uniformity is achieved.

  In the 1st and 2nd filter 37,38, the insoluble matter more than the predetermined magnitude | size in a liquid mixture is removed by an internal filter (not shown). In this embodiment, the number of filters is set to 2, and the absolute filtration accuracy is set such that the first filter 37 is larger than the second filter 38, thereby removing insoluble matter in stages according to size. Although the lifetime of the second filter is extended, the present invention does not depend on this aspect.

  The pressurizing and heating unit 41 performs the pressurizing and heating process in FIG. 1 and includes a pressure controller and a temperature controller (both not shown), and the temperature of the mixture is set to be equal to or higher than the boiling point of the solvent at normal pressure. Can do. Various known methods can be used for the control mechanism of pressure and temperature. In this embodiment, the pressure control is performed by introducing inert gas and a double jacket provided with a jacket for passing a heat transfer medium is used. Temperature control is implemented by the structure. The second cooling unit 42 has the same structure as the first cooling unit 32 except that no pressure controller is provided.

  In this embodiment, the polymer solution 23 was prepared by the following method using the polymer solution preparation apparatus 30 as described above. First, the polymer and the solvent are mixed in the first tank 31, and the polymer is swollen at a predetermined temperature. However, the flow order of the polymer and the solvent into the first tank 31 is not limited, and may be mixed in another container or the like and supplied to the first tank 31 as a mixed solution. When cellulose acylate and a solvent containing dichloromethane as a main solvent are mixed, in the swelling step 11 in the first tank 31, the polymer contains a solvent and becomes a transparent gel. However, this swollen state varies depending on the combination of the polymer and the solvent used, and may be a gel-like product having a translucent portion, for example.

  And in this swelling process 11, a mixture is controlled to become the temperature of -10 degreeC or more and 50 degrees C or less, and, thereby, a polymer and a solvent can fully be mixed and it can be set as a transparent gel-like mixture. If the temperature is lower than −10 ° C., the time required for swelling becomes longer, resulting in a decrease in productivity. If the temperature is higher than 50 ° C., the solvent boils or the polymer swells uniformly. However, there is a problem that the polymer solution prepared does not form lumps or particles (sometimes referred to as such). In addition, said suitable temperature range is based on the said combination of the polymer and solvent in this embodiment, and depending on these combinations etc., said upper limit temperature and minimum temperature may change about 10 degreeC in general.

  And in the 1st cooling process 12 in the 1st cooling part 32, it cools so that the temperature of a mixture may be -100 degreeC or more and -10 degrees C or less. Thereby, the swelling state of the polymer can be made more efficient and uniform. When the temperature is lower than −100 ° C., the time required for cooling becomes long, so that the productivity is lowered, and when the temperature is higher than −10 ° C., a uniform polymer solution can be produced. There are problems such as being unable to do so. Further, in order to improve the uniformity of swelling of the polymer, in the first cooling step 12, the mixture may be cooled while being pressurized using the pressure controller 32a.

  Moreover, in the heating process 13 by the heating part 35, it heats so that the temperature of a mixture may be 0 degreeC or more and 57 degrees C or less. Thereby, the polymer can be sufficiently dissolved. When the liquid supply path from the first cooling unit 32 to the second tank 36 is long and the ambient temperature is high, the heating unit 35 is provided when the mixture can be brought to a predetermined temperature within the above temperature range without being heated by the heating unit 35. It does n’t matter. When the temperature is lower than 0 ° C., the polymer is not sufficiently dissolved, the fluidity of the polymer solution is lowered, and when the temperature is higher than 57 ° C., the solvent boils. In this preferred temperature range, the upper limit temperature and the lower limit temperature may be changed by about 10 ° C. depending on the combination of the polymer and the solvent, and the like.

  Then, the mixture that has undergone the heating step 13 is stirred while being heated in the second tank 36 for a predetermined time as necessary, so that the concentration or dispersion concentration can be made uniform and the dissolution can proceed.

  According to the above method, since the solubility of the polymer in the solvent is improved as compared with the conventional method, even a polymer having many side chains can be dissolved. Thereby, in the film formed using the solution casting method and the main chain of the polymer molecule is oriented in the film surface direction, the side chain of the polymer molecule is oriented in the thickness direction of the film. Therefore, a polymer film having the above retardation value can be produced. Further, since the solubility of the polymer can be improved, the calculated concentration by the initial raw material charging and the concentration of the obtained polymer solution are almost the same value, so that a large concentration adjusting step is not necessary.

  By the way, the polymer used as the raw material of the polymer solution often contains unreacted substances such as monomers, polymers that did not become polymers, foreign matters such as dust, etc. May contaminate the polymer solution. Furthermore, there may be a gel-like substance or the like in the mixture which is judged to be extremely difficult to dissolve by any means due to its very large molecular weight. When a polymer solution mixed with such an undissolved material is formed, there are problems in that the film has irregularities and tears, and the optical properties and the like of the manufactured film deteriorate. Therefore, such a problem can be prevented by removing these undissolved substances by filtration.

  Furthermore, by providing the steps subsequent to the pressure heating step 16 as in this embodiment, a step for further improving the solubility of the polymer in the solvent can be performed. In the pressure heating process 16, the mixture is heated. The heating target temperature at this time shall be 60 degreeC or more and 240 degrees C or less. Pressure control is performed so that the liquid does not cause foaming or the like according to the heating temperature, and the pressure control range is 0.2 MPa or more and 30 MPa or less. Thereby, even if it is a case where it is more than the boiling point of a solvent, for example, heating becomes possible, and promotion of dissolution and preparation of a higher concentration polymer solution can be aimed at. When the temperature is lower than 60 ° C., the effect of pressure heating cannot be sufficiently obtained, and when the temperature is higher than 240 ° C., there are problems such as deterioration of the polymer and additives. Further, even if the pressure is made lower than 0.2 MPa, the control effect is thin, and if the pressure is made higher than 30 MPa, there are problems such as an increase in the cost of the apparatus and a reduction in safety. This temperature is basically based on the type of solvent, and tends to depend on its boiling point. Therefore, depending on the boiling point of the solvent, the upper limit temperature and the lower limit temperature may be changed approximately by about 10 ° C.

  The mixture that has undergone the pressure heating step 16 is cooled in the second cooling step 17 by the second cooling unit 42 to be 0 ° C. or higher and 57 ° C. or lower. Although the temperature of the mixture decreases even by natural cooling, it is preferable to provide a cooling means such as the second cooling part 42 in order to suppress the deterioration of the polymer and the like. Although not shown in FIG. 2, in this embodiment, a known flash distillation means is provided between the pressure heating unit 41 and the second cooling unit 42 to return the pressure to normal pressure and Although the concentration is increased, the method for releasing the high pressure and the presence or absence of the concentration adjustment are not limited in the present invention.

  In the present invention, the viscosity and dynamic storage modulus of the polymer solution obtained are not particularly limited. However, among them, the viscosity at 40 ° C. is 1 to 400 Pa · s, the dynamic storage elastic modulus at 15 ° C. is preferably 500 Pa or more, and more preferably the viscosity at 40 ° C. is 10 to 200 Pa · s. It is preferable that it is s and the dynamic storage elastic modulus in 15 degreeC is 100-1 million. Furthermore, it is preferable that the dynamic storage elastic modulus at a temperature lower than room temperature is larger. For example, when the support for casting is −5 ° C., the dynamic storage elastic modulus is 10,000 to 1,000,000 Pa at −5 ° C. Preferably, when the support is at −50 ° C., the dynamic storage elastic modulus at −50 ° C. is preferably 10,000 to 5 million Pa.

The above viscosity and dynamic storage elastic modulus were obtained by using a 1 mL sample of a polymer solution with a commercially available rheometer (model: CLS 500, manufactured by TA Instruments) and Steel Cone (produced by TA Instruments) having a diameter of 4 cm / 2 °. Oscillation Step / Temperature Ramp was measured under the condition of changing the range from 40 ° C. to −10 ° C. at 2 ° C./min, and the static non-Newtonian viscosity n ^* ((unit: Pa · s) and −5 ° C. at 40 ° C. The storage elastic modulus G ′ (unit: Pa) of the solution sample was determined, and the solution sample was preliminarily kept at the measurement start temperature, and then the measurement was started.

  In addition, about solubility, even if it is the combination of the same kind of polymer and solvent, it changes also with the difference in the raw material of a polymer, and the difference in a synthesis method. For example, even if it is a cellulose acylate, the solubility of the raw material made of wood pulp is different from that of cotton linter, and the solubility changes depending on the degree of acyl group substitution. Therefore, it is preferable to determine the presence or absence of the pressure control in the first cooling step 12 in FIG.

  Next, a method for producing a polymer film having the retardation value using the polymer solution will be described below. FIG. 3 is a process diagram showing an outline of the solution casting method embodying the present invention. The solution casting apparatus 70 includes a polymer solution preparation device 30 for preparing the polymer solution 23, a reserve tank 73 to which the polymer solution 23 from the polymer solution preparation device 30 is supplied, a liquid feeding pump 75, and a casting. A device 43, a tenter device 77, a roller drying device 81, and a winding device 82 are included.

  In the reserve tank 73, the polymer solution 23 is retained for a predetermined time to perform final preparation such as defoaming and concentration adjustment. The liquid feed pump 75 sends the polymer solution 23 from the delivery port 13a of the reserve tank 73 to the casting apparatus 43 at a predetermined flow rate. In this embodiment, a pressurized metering gear pump is used as the liquid feeding pump 75, and this is effective in that the liquid feeding amount can be adjusted with high accuracy by controlling the number of rotations of the gear. However, the present invention is not limited to this.

  The casting apparatus 43 has a casting die 85 and a metal drum 86 as a support. The type of casting die 85 is appropriately determined according to the casting method, and a pressure type is used in this embodiment. Instead of the drum 86, the support may be a band that is continuously conveyed while being supported by a backup roller. Further, a plurality of rollers 88 for supporting or conveying the film 87 peeled off from the drum 86 are installed between the casting device 43 and the winding device 82, and this number is the number shown in FIG. It does not depend on it and is increased or decreased as appropriate. Furthermore, these rollers are appropriately determined as to whether they are driven or not driven. In FIG. 3, only a part of these rollers 88 is shown in order to avoid complexity of the drawing.

  Note that the tenter device 77, the roller drying device 81, and the like are changed in the mutual positional relationship, the number of installed units, the combination, and the like according to the type of the film 87 to be manufactured. For example, when manufacturing a film used for a silver halide photographic light-sensitive material or a functional protective film for an electronic display, an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. Various coating devices for applying to the film 31 are often provided. Each such manufacturing facility or process is described in detail on pages 25 to 30 in, for example, the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). The process can be classified into casting such as co-casting and sequential casting, metal support, and drying, peeling, stretching, and the like.

  A method for producing the polymer film of the present invention using the solution casting apparatus 70 will be described below. The polymer solution 23 sent from the reserve tank 73 to the casting die 85 by the liquid feeding pump 75 is continuously cast on the rotating drum 86 from the die 85a of the casting die 85. The cast polymer solution 23 becomes a cast film 23 a on the drum 86, and is peeled off as a film 87 containing a solvent when it has self-supporting properties. The film 86 is continuously peeled off from the drum 86 by, for example, winding the film 87 around a roller 88 positioned on the most upstream roller, and rotating the most upstream roller.

  Here, the ambient temperature of the polymer solution 23 and the casting film 23a in the casting apparatus 43 is not particularly limited, but is preferably −50 to 50 ° C. This temperature is more preferably −30 to 40 ° C., and particularly preferably −20 to 30 ° C. When the polymer solution 23 is a cellulose ester solution, the polymer solution 23 was cast at a temperature lower than room temperature, cooled on the drum 26 instantaneously, and the gel strength was increased, thereby including an organic solvent. The film 87 in a state can be held. Thereby, it becomes possible to peel off from a support body in a short time, without evaporating an organic solvent from a cellulose ester, and high-speed casting can be implemented. In addition, when it is necessary to cool the casting apparatus 43 so that it may become in said temperature range, the cooling means is not specifically limited, For example, air may be sufficient as nitrogen, argon, helium. In this case, the relative humidity is preferably 0 to 70%, and more preferably 0 to 50%. Moreover, it is preferable that the temperature of the drum 26 is -50-130 degreeC, More preferably, it is -30-25 degreeC, More preferably, it is -20-15 degreeC. In order to maintain the ambient environment in the casting apparatus 16 at the above temperature, for example, it is preferable to introduce a cooled gas into the casting apparatus 16 that is a closed system or to equip the casting apparatus 43 with a cooler. Furthermore, in order to prevent the influence of moisture, introduction of dry air or the like is preferable.

  The film 87 peeled off is sent to the tenter device 77. In the tenter device 77, the film 87 is dried while being regulated in width and stretched. In the tenter device 77, a tenter clip (not shown) travels according to a tenter track (not shown) while holding both end portions of the film 87, and the film 87 is conveyed by the travel of the tenter clip. In some cases, the film 87 is pierced and held using a pin or the like instead of the tenter clip. The tenter clip is automatically controlled to be opened and closed by a controller (not shown), and the holding and releasing of the film 31 are controlled by the opening and closing. The tenter clip holding the film 87 travels inside the tenter device 77 and is automatically controlled to release the holding portion and release the holding of the film 87 when reaching a predetermined holding release point near the exit. .

  Thus, in the present invention, the optical anisotropy can be appropriately adjusted by optionally performing a stretching treatment on the polymer film 87. Therefore, it is preferable to carry out this stretching treatment in addition to the method for preparing the polymer solution. Stretching is usually performed in the longitudinal direction or the width direction, and may be uniaxial stretching or biaxial stretching. For example, by adjusting the speed of the transport roller of the film 87 so that the winding speed of the film 87 is faster than the stripping speed of the film 87, the film 87 is stretched in the longitudinal direction, As described above, the film can be conveyed while being held by the tenter clip, and can be stretched in the width direction by gradually increasing the distance between the tenter clips on both sides of the film. In addition, after the film 87 is dried, the film 87 can be stretched using a predetermined stretching machine such as uniaxial stretching using a long stretching machine. The draw ratio of the film 87 is preferably 0.5 to 300%, more preferably 1 to 200%, and sometimes 1 to 100%. This stretch ratio means a length y of an increase due to stretching with respect to a predetermined original length x, and is a value obtained by (y / x) × 100. Stretching may be performed in a single stage, or may be performed in multiple stages. In the case of performing in multiple stages, the product of each stretching ratio may be set within this range.

  Stretching is preferably performed at room temperature or under heating conditions and is preferably performed together with drying. For example, it is preferable that the solvent remains in the film 87 as in the present embodiment. When stretching under heating conditions, the heating temperature is preferably not more than the glass transition point Tg of the polymer.

  The stretching speed is preferably 5 to 1000% / min, and more preferably 10 to 500% / min. And it is preferable to extend | stretch using a heat roll and / or a radiant heat source (IR heater etc.), and warm air. Moreover, you may provide a thermostat in order to improve the uniformity of the film temperature during extending | stretching. About these extending | stretching processes, apply the technique described in invention technical report (public technical number 2001-1745, March 15, 2001, p.29-30, invention association) to this invention. Can do.

  The film 87 stretched by the tenter device 77 in this way is sent to a roller drying device 81 as a next process by a support or transport roller 88, and is sufficiently supported or transported by a plurality of rollers 81a. After being dried, it is wound up as a product.

  In this way, a polymer film having a controlled retardation value can be obtained. In addition, the present invention uses a sequential casting method or a co-casting method to cast a plurality of polymer solutions so that a single polymer film is produced. It is effective even in the case of producing a polymer film in which the molecular weight distribution and the kind of polymer have a distribution in the thickness direction. In such a case, each polymer solution to be co-cast or sequentially cast may be prepared by the steps shown in FIG. 1 or FIGS. The single polymer film thus obtained becomes a film with the retardation value controlled as described above. As described above, the film having a single layer structure used in the present invention is not a film in which a plurality of film materials are bonded to each other, but means a single polymer film, and has various distributions as described above. In addition to non-polymer films, the types and blending amounts of the above-mentioned additives, the molecular weight distribution of the polymer, the type of polymer, etc. have a distribution in the thickness direction, and further optical Also included are those having various functional parts such as an anisotropic part, an antiglare part, a gas barrier part, and a moisture resistant part.

  The width of the polymer film is preferably at least 100 cm or more, the variation of the Re value in the entire width direction is preferably within ± 5 nm, and more preferably within ± 3 nm. Further, the variation in Rth value is preferably within ± 10 nm, and more preferably within ± 5 nm. Further, it is preferable that the variation in the Re value and the Rth value in the length direction is equal to the variation in the width direction.

  Furthermore, the film of this invention can be used for various optical uses, and this invention contains the polarizing plate, retardation plate, image display apparatus, etc. which used this film.

  In recent years, LCDs such as televisions, notebook personal computers, and mobile portable terminals are required to increase brightness with less power. Therefore, optical members used in these LCDs are required to have high transmittance. From such a viewpoint, in the polymer film of the present invention, it is preferable that the spectral transmittance at a wavelength of 380 nm is 45% or more and 95% or less and the spectral transmittance at a wavelength of 350 nm is 10% or less.

  When the above polymer film is used for various optical applications as described above, it is usually formed into a multilayer structure by bonding with another functional film or forming a coating layer. Examples of the functional layer to be applied include a polarizing film and an undercoat layer. Thus, when providing another layer, it is preferable to surface-treat the polymer film obtained by the predetermined method depending on the case. Thereby, the adhesiveness of a polymer film and various functional layers can be improved.

  As the surface treatment method, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. With respect to these, the technology described in the Technical Report of the Invention Association (Public Technical Number 2001-1745, issued on March 15, 2001, p.30-32, Invention Association) can be applied to the present invention.

  For the undercoat layer, the technology described in the Invention Association's public technical report (Public Technical Number 2001-1745, issued on March 15, 2001, p. 32, Invention Association) can be applied to the present invention. As for the functional layer of the polymer film, various functional layers are described in the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, p.32-45, Japan Society for Invention). Can be appropriately applied to the present invention.

  In addition, the polymer film of the present invention may optionally be provided with an optically anisotropic layer formed from a liquid crystalline compound, which can be preferably applied particularly to an OCB mode LCD.

[Optically anisotropic layer]
The optically anisotropic layer may be directly formed on the surface of the polymer film of the present invention that is made transparent, or may be formed on the alignment film by forming an alignment film on the polymer film. Moreover, it is also possible to produce the optical compensation film of the present invention by transferring a liquid crystalline compound layer formed on another substrate onto a polymer film using an adhesive, an adhesive, or the like. Examples of the liquid crystalline compound used for forming the optically anisotropic layer include a rod-like liquid crystalline compound and a discotic liquid crystalline compound (hereinafter, the discotic liquid crystalline compound may be referred to as a “discotic liquid crystalline compound”). The rod-like liquid crystal compound and the discotic liquid crystal compound may be a high-molecular liquid crystal or a low-molecular liquid crystal. In addition, the compound finally contained in the optically anisotropic layer no longer needs to exhibit liquid crystallinity. For example, when a low-molecular liquid crystalline compound is used for the production of the optically anisotropic layer, the optically anisotropic layer In the process of forming, the compound may be cross-linked and no longer exhibits liquid crystallinity.

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds that can be used in the present invention include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, and cyano-substituted phenylpyrimidines. Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. The rod-like liquid crystal compound includes a metal complex. A liquid crystal polymer containing a rod-like liquid crystal compound in a repeating unit can also be used. In other words, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer. For rod-like liquid crystalline compounds, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemical Review Vol. 22 Liquid Crystal Chemistry (1994) edited by the Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.

  The birefringence of the rod-like liquid crystalline compound used in the present invention is preferably in the range of 0.001 to 0.7. The rod-like liquid crystalline compound preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  The discotic liquid crystalline compound exhibits liquid crystallinity with a structure in which a linear alkyl group, an alkoxy group or a substituted benzoyloxy group is radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. Also included are compounds. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation.

  As described above, when an optically anisotropic layer is formed from a liquid crystalline compound, the compound finally contained in the optically anisotropic layer no longer needs to exhibit liquid crystallinity. For example, a low-molecular discotic liquid crystalline compound has a group that reacts with heat or light, and the group reacts with heat or light to polymerize or crosslink to increase the molecular weight. When a layer is formed, the compound contained in the optically anisotropic layer may no longer have liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. The polymerization of discotic liquid crystalline compounds is described in JP-A-8-27284.

  In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Accordingly, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula (III).

Formula (III) D (-LQ) n
In the formula, D is a discotic core, L is a divalent linking group, Q is a polymerizable group, and n is an integer of 4 to 12.

  An example of the disk-shaped core (D) is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

  In the formula (III), the divalent linking group (L) is selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. A divalent linking group selected is preferable. The divalent linking group (L) is a divalent combination of at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO-, -NH-, -O- and S-. The linking group is more preferable. The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and O- are combined. preferable. The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The arylene group preferably has 6 to 10 carbon atoms.

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. The alkylene group, alkenylene group and arylene group may have a substituent (eg, alkyl group).
L1: -AL-CO-O-AL-
L2: -AL-CO-O-AL-O-
L3: -AL-CO-O-AL-O-AL-
L4: -AL-CO-O-AL-O-CO-
L5: -CO-AR-O-AL-
L6: -CO-AR-O-AL-O-
L7: -CO-AR-O-AL-O-CO-
L8: -CO-NH-AL-
L9: -NH-AL-O-
L10: -NH-AL-O-CO-

L11: -O-AL-
L12: -O-AL-O-
L13: -O-AL-O-CO-
L14: -O-AL-O-CO-NH-AL-
L15: -O-AL-S-AL-
L16: -O-CO-AR-O-AL-CO-
L17: -O-CO-AR-O-AL-O-CO-
L18: -O-CO-AR-O-AL-O-AL-O-CO-
L19: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L20: -S-AL-
L21: -S-AL-O-
L22: -S-AL-O-CO-
L23: -S-AL-S-AL-
L24: -S-AR-AL-

  The polymerizable group (Q) of the formula (III) is determined according to the type of polymerization reaction. The polymerizable group (Q) is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group. In formula (III), n is an integer of 4-12. A specific number is determined according to the type of the disk-shaped core (D). In addition, although the combination of several L and Q may differ, it is preferable that it is the same.

  In the present invention, molecules of the rod-like compound or the discotic compound are fixed in an oriented state in the optically anisotropic layer. The orientation average direction of the molecular symmetry axis of the liquid crystal compound at the interface on the transparent film side has an intersecting angle with the slow axis in the plane of the transparent film of about 45 degrees. In this specification, “substantially 45 °” refers to an angle in the range of 45 ° ± 5 °, preferably 42 to 48 °, and more preferably 43 to 47 °. The average direction of the molecular symmetry axis of the liquid crystalline compound in the optically anisotropic layer is preferably 43 to 47 ° with respect to the longitudinal direction of the support (that is, the fast axis direction of the support).

  The orientation average direction of the molecular symmetry axis of the liquid crystal compound can be generally adjusted by selecting a material of the liquid crystal compound or the alignment film or by selecting a rubbing treatment method. In the present invention, for example, when the alignment film for forming an optically anisotropic layer is produced by rubbing treatment, the liquid crystalline compound is obtained by rubbing treatment in a direction of 45 ° with respect to the slow axis of the polymer film of the present invention. An optically anisotropic layer in which the orientation average direction of the molecular symmetry axis at least at the polymer film interface is 45 ° with respect to the slow axis of the polymer film can be formed. For example, the optical compensation film can be continuously produced by using a long transparent polymer film of the present invention in which the slow axis is parallel to the longitudinal direction. Specifically, a coating solution for forming an alignment film is continuously applied to the surface of a long polymer film to prepare a film, and then the surface of the film is continuously oriented in the direction of 45 ° in the longitudinal direction. An alignment film is prepared by rubbing, and then a coating liquid for forming an optically anisotropic layer containing a liquid crystalline compound is continuously applied on the prepared alignment film to align the molecules of the liquid crystalline compound. By fixing in this state, an optically anisotropic layer can be produced, and a long optical compensation film can be produced continuously. The optical compensation film produced in a long shape is cut into a desired shape before being incorporated in the liquid crystal display device.

  In addition, regarding the orientation average direction of the molecular symmetry axis on the surface side (air side) of the liquid crystalline compound, the orientation average direction of the molecular symmetry axis of the liquid crystalline compound on the air interface side is approximately 45 with respect to the slow axis of the polymer film. It is preferable that it is (degree), It is more preferable that it is 42-48 degrees, It is further more preferable that it is 43-47 degrees. In general, the orientation average direction of the molecular symmetry axis of the liquid crystal compound on the air interface side can be adjusted by selecting the type of the liquid crystal compound or the additive used together with the liquid crystal compound. Examples of the additive used together with the liquid crystal compound include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the molecular symmetry axis can also be adjusted by selecting the liquid crystalline compound and the additive as described above. In particular, with respect to the surfactant, it is preferable that the surface tension control of the coating solution is compatible.

  The plasticizer, surfactant and polymerizable monomer used together with the liquid crystal compound are compatible with the discotic liquid crystal compound and can change the tilt angle of the liquid crystal compound or do not inhibit the alignment. Is preferred. Polymerizable monomers (eg, compounds having a vinyl group, a vinyloxy group, an acryloyl group and a methacryloyl group) are preferred. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the liquid crystalline compound. In addition, when a monomer having 4 or more polymerizable reactive functional groups is mixed and used, the adhesion between the alignment film and the optically anisotropic layer can be enhanced.

  When a discotic liquid crystalline compound is used as the liquid crystalline compound, it is preferable to use a polymer that has a certain degree of compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound. A cellulose ester can be mentioned as an example of a polymer. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose, and cellulose acetate butyrate. In order not to inhibit the orientation of the discotic liquid crystalline compound, the amount of the polymer added is preferably in the range of 0.1 to 10% by mass, preferably 0.1 to 8% by mass with respect to the discotic liquid crystalline compound. More preferably, it is in the range of 0.1 to 5% by mass. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

  In the present invention, the optically anisotropic layer has at least in-plane optical anisotropy. The in-plane retardation Re of the optically anisotropic layer is preferably 3 to 300 nm, more preferably 5 to 200 nm, and even more preferably 10 to 100 nm. The retardation Rth in the thickness direction of the optically anisotropic layer is preferably 20 to 400 nm, and more preferably 50 to 200 nm. The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

(Alignment film)
The alignment film is formed between the film and the optically anisotropic layer. Alternatively, the alignment film may be used only when the optically anisotropic layer is formed, and after the optically anisotropic layer is formed on the alignment film, only the optically anisotropic layer may be transferred onto the transparent film. . The alignment film is preferably a layer made of a crosslinked polymer. The polymer used for the alignment film may be either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent. The alignment film is formed by reacting a polymer having a functional group or a polymer having a functional group introduced therein with light, heat, pH change, or the like, or a compound having a high reaction activity. Can be formed by introducing a linking group derived from a cross-linking agent between polymers to cross-link between the polymers.

  The alignment film composed of a crosslinked polymer can be usually formed by applying a coating solution containing the polymer or a mixture of a polymer and a crosslinking agent on a support, followed by heating. In the rubbing process described later, it is preferable to increase the degree of crosslinking in order to suppress the dust generation of the alignment film. A value (1- (Ma / Mb)) obtained by subtracting 1 from the ratio (Ma / Mb) of the amount (Ma) of the crosslinking agent remaining after crosslinking to the amount (Mb) of the crosslinking agent added to the coating solution. When Mb)) is defined as the degree of crosslinking, the degree of crosslinking is preferably 50 to 100%, more preferably 65 to 100%, and most preferably 75 to 100%.

  In the present invention, the polymer used for the alignment film may be either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent. Of course, a polymer having both functions can also be used. Examples of the polymer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol acrylamide). ), Styrene / vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, carboxymethylcellulose -Polymers such as silica, gelatin, polyethylene, polypropylene and polycarbonate and compounds such as silane coupling agents. Examples of preferred polymers are water-soluble polymers such as poly (N-methylacrylamide), carboxymethyl cellulose, gelatin, polyville alcohol, and modified polyvinyl alcohol, and gelatin, polyville alcohol, and modified polyvinyl alcohol. Are preferable, and in particular, polyvinyl alcohol and modified polyvinyl alcohol can be mentioned.

Among the above polymers, polyvinyl alcohol or modified polyvinyl alcohol is preferable. Examples of the polyvinyl alcohol include those having a saponification degree of 70 to 100%, generally those having a saponification degree of 80 to 100%, and more preferably those having a saponification degree of 82 to 98%. The degree of polymerization is preferably in the range of 100 to 3000. Examples of the modified polyvinyl alcohol include those modified by copolymerization (for example, COONa, Si (OX) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO, SO ₃ Na, C ₁₂ H _25, etc. Modified by chain transfer (for example, COONa, SH, SC ₁₂ H _25, etc. are introduced as modifying groups), modified by block polymerization (modified groups such as COOH, for example) , CONH ₂ , COOR, C ₆ H _5, etc. are introduced). As a polymerization degree, the range of 100-3000 is preferable. Among these, unmodified or modified polyvinyl alcohol having a saponification degree of 80 to 100% is preferable, and unmodified or alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% is more preferable.

  As the modified polyvinyl alcohol used for the alignment film, a reaction product of a compound represented by the following general formula (6) and polyvinyl alcohol is preferable.

In the formula, R ^1d represents an unsubstituted alkyl group or an alkyl group substituted with an acrylolyl group, a methacryloyl group or an epoxy group, W represents a halogen atom, an alkyl group or an alkoxy group, and X ^1d represents an active ester, an acid A group of atoms necessary for forming an anhydride or acid halide is represented, l represents 0 or 1, and n represents an integer of 0 to 4.

  Moreover, as the modified polyvinyl alcohol used for the alignment film, a reaction product of a compound represented by the following general formula (7) and polyvinyl alcohol is also preferable.

In the formula, X ^2d represents an atomic group necessary for forming an active ester, an acid anhydride or an acid halide, and m represents an integer of 2 to 24.

  The polyvinyl alcohol used for reacting with the compounds represented by the general formula (6) and the general formula (7) includes the unmodified polyvinyl alcohol and the copolymer-modified one, that is, chain transfer. Examples include modified products of polyvinyl alcohol such as modified products and modified products by block polymerization. Preferred examples of the specific modified polyvinyl alcohol are described in detail in JP-A-8-338913. In the case of using a hydrophilic polymer such as polyvinyl alcohol for the alignment film, it is preferable to control the water content from the viewpoint of the degree of hardening, preferably 0.4 to 2.5%, and 0.6 to 1 More preferably, it is 6%. The water content can be measured with a commercially available Karl Fischer moisture content measuring device. The alignment film preferably has a thickness of 10 μm or less.

  And the polymer film of this invention can be preferably used for a polarizing plate, and the polarizing plate of this invention is obtained by the said embodiment on both surfaces of the polarizing film produced with the polyvinyl alcohol (PVA) type film, for example. It is obtained by laminating an acylate film as a protective film. However, in this invention, the manufacturing method of a polarizing plate is not limited, It can manufacture by well-known various manufacturing methods.

  The polarizing film is obtained by dyeing a polyvinyl alcohol film. As the dyeing method, a gas phase adsorption method and a liquid phase adsorption method are generally used, and both can be applied. Staining by adsorption was performed.

  For dyeing by liquid phase adsorption, iodine is used here, but the present invention is not limited to this. The polyvinyl alcohol film was immersed in an iodine / potassium iodide (KI) aqueous solution with an immersion time of 30 seconds or more and 5000 seconds or less and stretched. The aqueous solution at this time preferably has an iodine concentration of 0.1 g / liter to 20 g / liter and a potassium iodide concentration of 1 g / liter to 100 g / liter. Moreover, it is preferable that the temperature of the aqueous solution at the time of immersion is set to the range of 5 degreeC or more and 50 degrees C or less.

  The liquid phase adsorption method is not limited to the above immersion method, and a known method such as a method of applying iodine or other dye solution to a polyvinyl alcohol film or a method of spraying may be applied. Dyeing may be performed before or after the polyvinyl alcohol film is stretched, but the polyvinyl alcohol film is appropriately swelled and easily stretched by being dyed, so that the stretching step It is particularly preferable to provide a dyeing step before or during stretching.

  It is also preferable to dye with a dichroic dye instead of iodine. Examples of dichroic dyes include dye compounds such as azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, anthraquinone dyes. it can. Water-soluble dye compounds are most preferable. Further, it is preferable that a hydrophilic functional group such as a sulfonic acid group, an amino group, or a hydroxyl group is introduced into the molecule of these dichroic dyes.

  In the step of producing a polarizing film by stretching a dyed polyvinyl alcohol film, a compound that crosslinks polyvinyl alcohol is used. Specifically, a polyvinyl alcohol film is immersed in a crosslinking agent solution in the pre-stretching step or the stretching step to contain a crosslinking agent. It may be applied instead of dipping. The polyvinyl alcohol film is sufficiently hardened by the inclusion of the crosslinking agent, and as a result, appropriate orientation is imparted. In addition, as a crosslinking agent of polyvinyl alcohol, boric acids are most preferable, but are not limited thereto.

  On the other hand, when the cellulose acylate film according to the embodiment is used as a protective film, it is preferable that the adhesion surface is surface-treated by the above-described various surface treatment methods before adhesion to the polarizing film. In this embodiment, alkali treatment is used as the surface treatment method. However, instead of alkali treatment, easy adhesion processing described in JP-A-6-94915 and JP-A-6-118232 may be performed. Good.

  As the adhesive or pressure-sensitive adhesive between the polarizing film and the cellulose acylate film thus obtained, various known adhesives or pressure-sensitive adhesives that can be used for bonding the polarizing film and the protective film can be used. Among them, preferable examples include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, and vinyl latexes such as butyl acrylate. In this embodiment, completely saponified polyvinyl alcohol is used.

  The polarizing plate is composed of a polarizing film that is a polarizer and protective films for protecting both surfaces thereof. In this embodiment, the polymer film according to the above embodiment is used as this protective film. Furthermore, one film each is bonded to both surfaces of the obtained polarizing plate for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate or at the time of product inspection. One of the films is sometimes referred to as an external protective film, and is used for the purpose of protecting the surface of the polarizing plate, and is disposed on the surface opposite to the surface on which the polarizing plate is bonded to the liquid crystal plate. Moreover, since the other film may be called an external separate film and is used for the purpose of covering the adhesive layer bonded to the liquid crystal plate, it is used on the side of the surface where the polarizing plate is bonded to the liquid crystal plate. A liquid crystal display device is usually provided with a liquid crystal cell between two polarizing plates. Generally, as described above, a liquid crystal cell has a liquid crystal compound injected between two alignment films. . Therefore, such a liquid crystal display device has four protective films, and the polymer film of the present invention can provide excellent display properties for any of these four sheets. In particular, the film of the present invention can be preferably used as a protective film between a polarizing film and a liquid crystal cell in a liquid crystal display device, and at this time, can function as a retardation plate. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.

  The polarizing plate of the present invention can be produced by a production method having a drying step in which the polarizing film is stretched and then contracted to reduce the volatile content, and the production step is at least after drying or during drying. It is preferable to further include a post-heating step after the transparent protective film is bonded to one side. In the aspect in which the above-described transparent polymer film of the present invention is a protective film, which also serves as a support for an optically anisotropic layer functioning as an optical compensation film, a transparent protective film is provided on one side, and the opposite side is provided. It is preferable to post-heat after bonding the transparent support body which has an optically anisotropic layer. As a specific pasting method, during the film drying process, the transparent protective film is pasted to the polarizing film using an adhesive while holding both ends, and then both ends are cut off, or both ends are held after drying. There is a method of releasing the polarizing film and removing the both ends of the film and then attaching a transparent protective film. As a method for cutting off the ears, general techniques such as a method of cutting with a cutter such as a blade or a method of using a laser can be used. After bonding, it is preferable to heat in order to dry the adhesive and improve the polarization performance. The heating condition varies depending on the adhesive, but in the case of an aqueous system, it is preferably 30 ° C. or higher, more preferably 40 to 100 ° C., and further preferably 50 to 90 ° C. It is more preferable in terms of performance and production efficiency that these processes are manufactured in a consistent line.

  Optical properties and durability (short-term and long-term storage stability) of a polarizing plate comprising a transparent protective film, a polarizer and a transparent support related to the present invention are commercially available super high contrast products (for example, Sanritz Corporation). Manufactured by HLC2-5618 and the like) and preferably have equivalent or better performance. Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization {(Tp−Tc) / (Tp + Tc)} 1/2 ≧ 0.9995 (where Tp is parallel transmittance, and Tc is orthogonal transmission) The rate of change in light transmittance before and after standing in an atmosphere of 60 ° C. and humidity 90% RH for 500 hours and 80 ° C. in a dry atmosphere for 500 hours is 3% or less based on the absolute value, Further, it is preferable that the change rate of the polarization degree is 1% or less, further 1% or less, further 0.1% or less based on the absolute value.

  The polymer film of the present invention and the retardation plate, optical compensation sheet, and polarizing plate using the polymer film can be used for liquid crystal display devices in various display modes. Display modes include TN, IPS, FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Crystal), OCB, STN (Super Twisted Nematic), VA, and HAN (Hybrid). . In addition, a display mode in which the display mode is divided into orientations has been proposed. Further, it can be suitably used in any of a transmissive type, a reflective type, and a transflective liquid crystal display device.

  And when using the polymer film of this invention as a phase difference plate or a support body of a phase difference plate, it can use suitably also in said any display mode. These display modes are well known, and for example, TN type reflective liquid crystal display devices are described in JP-A-10-123478, WO98848320, and Japanese Patent No. 3022477. Further, the optical compensation sheet of the reflection type liquid crystal display device is described in WO00-65384. The polymer film of the present invention is also suitably used as a support for an optical compensation sheet of an ASM type liquid crystal display device having a liquid crystal cell in an ASM (axially aligned microcell) mode. This ASM mode liquid crystal cell is characterized in that the thickness of the cell is maintained by a position-adjustable resin spacer, and other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device are described in Kume et al. (Kume et al., SID 98 Digest 1089 (1998)). The applications of the polymer film of the present invention described above are those described in detail in pages 45 to 59 of the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). be able to.

(TN type liquid crystal display device)
The transparent polymer film according to the present invention may be used as a support for a retardation plate of a TN type liquid crystal display device having a TN mode liquid crystal cell. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. As for the optical compensation sheet used in the TN type liquid crystal display device, in addition to JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572, Mori (Mori) ) Other papers (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068).

(STN type liquid crystal display device)
The transparent polymer film of the present invention may be used as a support for a retardation plate of an STN type liquid crystal display device having an STN mode liquid crystal cell. In general, in a STN type liquid crystal display device, rod-like liquid crystalline molecules in a liquid crystal cell are twisted in a range of 90 to 360 degrees, and the refractive index anisotropy (Δn) and cell gap (d) of the rod-like liquid crystalline molecules. Product (Δnd) is in the range of 300 to 1500 nm. The optical compensation sheet used for the STN type liquid crystal display device is described in JP-A-2000-105316.

(VA type liquid crystal display device)
An embodiment in which the film of the present invention is applied to a particularly preferred VA mode liquid crystal display device will be described with reference to FIG. The liquid crystal display device shown in FIG. 4 includes a liquid crystal cell 101, an upper polarizing film 102 and a lower polarizing film 103 that are disposed so as to sandwich the liquid crystal cell 101, and an optical element between the upper polarizing film 102 and the liquid crystal cell 101. A compensation film 106 and an optical compensation film 107 are provided between the lower polarizing film 101 and the liquid crystal cell 101. As described above, only one of the optical compensation film 106 and the optical compensation film 107 may be used depending on the configuration. Further, although the polarizing films 102 and 103 are respectively protected by a pair of transparent protective films, only the transparent protective films 108 and 109 arranged on the side close to the liquid crystal cell 101 are shown in FIG. Is omitted for the transparent protective film disposed on the opposite side. Moreover, the optical compensation film 106 and the transparent protective film 108 can be replaced with these and can be a single film having both functions. Similarly, the optical compensation film 107 and the transparent protective film 109 can be replaced with these films as a single film having both functions.

  The liquid crystal cell 101 includes an upper substrate 111 and a lower substrate 112 and a liquid crystal layer formed by liquid crystal molecules 113 sandwiched therebetween. An alignment film (not shown) is formed on the surfaces of the substrates 111 and 112 that are in contact with the liquid crystal molecules 113 (hereinafter sometimes referred to as “inner surfaces”), and the liquid crystal molecules 113 in a state in which no voltage is applied or in a low application state. Is controlled in the vertical direction. Further, on the inner surfaces of the substrates 111 and 112, a transparent electrode (not shown) capable of applying a voltage to the liquid crystal layer made of the liquid crystal molecules 113 is formed. In the present invention, the product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn is preferably 0.1 to 1.0 μm. Furthermore, the optimum value of Δn · d is more preferably 0.2 to 1.0 μm, and further preferably 0.2 to 0.5 μm. In these ranges, since the white display luminance is high and the black display luminance is low, a bright and high-contrast display device can be obtained. The liquid crystal material to be used is not particularly limited. However, in an aspect in which an electric field is applied between the upper substrate 111 and the lower substrate 112, the dielectric anisotropy is such that the liquid crystal molecules 113 respond perpendicularly to the electric field direction. Use negative liquid crystal material. Further, when an electrode is formed only on one of the substrates 111 and 112 and an electric field is applied in a lateral direction parallel to the substrate surface, a liquid crystal material having a positive dielectric anisotropy is used. be able to.

  For example, when the liquid crystal cell 101 is a VA mode liquid crystal cell, a nematic liquid crystal material having a negative dielectric anisotropy between the upper and lower substrates 111 and 112 and Δn = 0.0813 and Δε = −4.6. Etc. can be used. The thickness d of the liquid crystal layer is not particularly limited, but can be set to about 3.5 μm when the liquid crystal having the characteristics in the above range is used. Since the brightness at the time of white display changes depending on the magnitude of the product Δn · d of the thickness d and the refractive index anisotropy Δn, Δn · d is 0.2 to 0.0 in order to obtain the maximum brightness. It is preferable to set it in the range of 5 μm.

  In addition, in the VA mode liquid crystal display device, the addition of a chiral material generally used in the TN mode liquid crystal display device is rarely used to degrade the dynamic response characteristics, but in order to reduce alignment defects. May be added. In addition, the multi-domain structure is advantageous for adjusting the alignment of the liquid crystal molecules in the boundary region between the domains. A multi-domain structure refers to a structure in which one pixel of a liquid crystal display device is divided into a plurality of regions. For example, in the VA mode, the liquid crystal molecules 113 are tilted when displaying white, so the birefringence of the liquid crystal molecules 113 when viewed from an oblique direction is different between the tilt direction and the opposite direction, and there is a difference in luminance and color tone. However, a multi-domain structure is preferable because the viewing angle characteristics of luminance and color tone are improved. Specifically, each pixel is composed of two or more (preferably 4 or 8) regions in which the initial alignment state of the liquid crystal molecules is different from each other, and averaging is performed. Can be reduced. Further, the same effect can be obtained even if each pixel is constituted by two or more different regions where the alignment direction of liquid crystal molecules continuously changes in a voltage application state.

  In order to form a plurality of regions having different alignment directions of the liquid crystal molecules 113 in one pixel, for example, a method of providing a slit in the electrode, providing a protrusion, changing the electric field direction, or biasing the electric field density is used. Can be used. In order to obtain a uniform viewing angle in all directions, the number of divisions may be increased. However, a substantially uniform viewing angle can be obtained by using four or more divisions. In particular, it is preferable that the polarizing plate absorption axis can be set at an arbitrary angle when dividing into eight. At the region boundary of each domain, the liquid crystal molecules 7 tend to hardly respond. In the normally black mode such as the VA mode, since black display is maintained, a decrease in luminance becomes a problem. Therefore, it is possible to reduce the boundary region between domains by adding a chiral agent to the liquid crystal material. On the other hand, since the white display state is maintained in the normally white mode, the front contrast is lowered. Therefore, a light shielding layer such as a black matrix covering the region may be provided.

  The slow axes of the protective films 108 and 109 on the side close to the liquid crystal layer of the polarizing film 102 and the polarizing film 103 are denoted by reference numerals 108x and 109x. The slow axis 108x and the slow axis 109x are preferably substantially parallel or orthogonal to each other. If the slow axis 108x and the slow axis 109x are orthogonal to each other, the optical characteristics of light perpendicularly incident on the liquid crystal display device are deteriorated by canceling the birefringence of the respective protective films 108 and 109. Can be reduced. Further, in a mode in which the slow axis 108x and the slow axis 109x are parallel to each other, when the liquid crystal layer has a residual phase difference, the phase difference can be compensated by the birefringence of the protective film.

  In FIG. 4, the absorption axes of the polarizing films 102 and 103 are denoted by reference numerals 102x and 103x. The directions of the absorption axes 102x and 103x of the polarizing films 102 and 103, the directions of the slow axes 108x and 109x of the protective films 108 and 109, and the alignment direction of the liquid crystal molecules 113 are the materials used for each member, The optimum range is adjusted according to the display mode, the laminated structure of the members, and the like. That is, the absorption axis 102x of the polarizing film 102 and the absorption axis 103x of the polarizing film 103 are arranged so as to be substantially orthogonal to each other. However, the liquid crystal display device of the present invention is not limited to this configuration.

  The optical compensation films 106 and 107 disposed between the polarizing film 102 and the polarizing film 103 and the liquid crystal cell 101 use the polymer film of the present invention. As described above, for example, a birefringent polymer is used. It consists of a film, a laminate of a transparent support and an optically anisotropic layer comprising liquid crystal molecules formed on the transparent support. The in-plane slow axis 106x of the optical compensation film 106 is preferably arranged so as to be substantially orthogonal to the absorption axis 102x of the polarizing film 102 located closer to it. Similarly, it is preferable to arrange the slow axis 107x in the plane of the optical compensation film 107 so as to be substantially orthogonal to the absorption axis 103x of the polarizing film 103 located closer to it. When arranged in such a relationship, the optical compensation film 106 or the optical compensation film 107 does not cause light leakage by causing retardation with respect to incident light from the normal direction, and incident light from an oblique direction. In contrast, the effects of the present invention can be sufficiently achieved.

  Further, when both the Re value and the Rth value of the protective film 108 are not 0 nm, the protective film 108 can also exhibit optical compensation ability. In this case, deficiencies in the functions of Re and Rth of the optical compensation film provided separately can be compensated. The same applies to the protective film 109.

  In a non-driving state in which a driving voltage is not applied to the respective transparent electrodes (not shown) of the substrates 111 and 112, the liquid crystal molecules 113 in the liquid crystal layer are aligned substantially perpendicular to the substrates 111 and 112, and as a result, pass through. The polarization state of the transmitted light hardly changes. Since the absorption axis 102x and the absorption axis 103x are orthogonal to each other, the light incident from the lower side (for example, the back electrode) is polarized by the polarizing film 103 and passes through the liquid crystal cell 101 while maintaining the polarization state. Blocked by the membrane 102. That is, the liquid crystal display device of FIG. 4 realizes an ideal black display in the non-driven state. On the other hand, in a driving state in which a driving voltage is applied to a transparent electrode (not shown), the liquid crystal molecules 113 are tilted in a direction parallel to the substrates 111 and 112, and light passing therethrough is polarized by the tilted liquid crystal molecules 113. Change. Therefore, light incident from the lower side (for example, the back electrode) is polarized by the polarizing film 103 and further passes through the liquid crystal cell 101 to change the polarization state and pass through the polarizing film 102. That is, white display can be obtained in a driving state where a voltage is applied.

  The feature of the VA mode is a high contrast. However, the conventional VA mode liquid crystal display device has a problem that the contrast is high in the front, but decreases in the oblique direction. At the time of black display, the liquid crystal molecules 113 are aligned perpendicular to the substrates 111 and 112. Therefore, when viewed from the front, the liquid crystal molecules 113 have almost no birefringence, so that the transmittance is low and a high contrast is obtained. However, birefringence occurs in the liquid crystal molecules 113 when observed from an oblique direction. Further, the crossing angle of the absorption axes 102x and 103x of the upper and lower polarizing films 102 and 103 is 90 ° orthogonal at the front, but is larger than 90 ° when viewed obliquely. Conventionally, due to these two factors, there has been a problem that leakage light is generated in an oblique direction and the contrast is lowered. In the liquid crystal display device of the present invention having the structure shown in FIG. 4, the film 87 of the present invention in which the retardation in each of R, G, and B satisfies a specific condition, that is, has the wavelength dependency of the specific retardation (FIG. 3). The light leakage in an oblique direction during black display is reduced and the contrast is improved.

  In the present invention, the configuration of the liquid crystal display device is not limited to the mode shown in FIG. 4, and may include other members. For example, a color filter may be disposed between the liquid crystal cell and the polarizing film. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight having a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface.

  In the present invention, the liquid crystal display device includes an image direct view type, an image projection type, and a light modulation type. The present invention is particularly effective when applied to an active matrix liquid crystal display device using three-terminal or two-terminal semiconductor elements such as TFT and MIM. Of course, an embodiment applied to a passive matrix liquid crystal display device represented by STN type called time-division driving is also effective.

(IPS type liquid crystal display device and ECB type liquid crystal display device)
The transparent polymer film of the present invention is particularly advantageous as a retardation plate for a IPS liquid crystal display device having an IPS mode or ECB mode liquid crystal cell and a support for a retardation plate or a protective film for a polarizing plate of an ECB liquid crystal display device. Used for. In these modes, the liquid crystal material is aligned substantially in parallel during black display, and black is displayed by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, the polarizing plate using the transparent polymer film of the present invention contributes to widening the viewing angle and improving the contrast.

(OCB type liquid crystal display device)
An OCB mode liquid crystal display device in which the polymer film of the present invention is particularly preferably used will be described with reference to FIG. The liquid crystal display device shown in FIG. 5 includes a liquid crystal cell 131. The liquid crystal cell 131 includes a liquid crystal layer 132 in which the liquid crystal bends with respect to the surfaces of the substrates 133 and 134 when a voltage is applied, that is, when black is displayed. An upper substrate 133 and a lower substrate 134 are sandwiched. The substrates 133 and 134 are subjected to alignment treatment on the liquid crystal surface, and the rubbing direction is indicated by an arrow RD. In the case of the back surface, the arrow line RD is indicated by a broken line. Polarizing films 137 and 138 are arranged with the liquid crystal cell 131 interposed therebetween. The polarizing films 137 and 138 are arranged so that the transmission axes 137x and 138x of the polarizing films 137 and 138 are orthogonal to each other and have an angle of 45 degrees with the RD direction of the liquid crystal layer 132 of the liquid crystal cell 131. Transparent polymer films 141 and 142 and optically anisotropic layers 144 and 145 are disposed between the polarizing films 137 and 138 and the liquid crystal cell 131, respectively. In the transparent polymer films 141 and 142, the slow axes 141x and 142x are parallel to the directions of the transmission axes 137x and 138x of the polarizing films 137 and 138 adjacent thereto, respectively. The optically anisotropic layers 144 and 145 have optical anisotropy expressed by the orientation of the liquid crystal compound.

  The liquid crystal cell 131 in FIG. 5 is as described above. It consists of an upper substrate 133 and a lower substrate 134 and a liquid crystal layer formed of liquid crystal molecules 132 sandwiched between them. An alignment film (not shown) is formed on the surfaces of the substrates 133 and 134 that are in contact with the liquid crystal molecules (hereinafter sometimes referred to as “inner surfaces”), and the alignment of the liquid crystal molecules in a state in which no voltage is applied or in a state where a voltage is not applied. Is controlled in a parallel direction with a pretilt angle. Further, on the inner surfaces of the substrates 133 and 134, transparent electrodes (not shown) capable of applying a voltage to the liquid crystal layer 132 made of liquid crystal molecules are formed. In the present invention, the product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn is preferably 0.1 to 1.5 μm, and more preferably 0.2 to 1.5 μm. More preferably, it is more preferably 0.2 to 1.2 μm, and even more preferably 0.6 to 0.9 μm. In these ranges, since the white display luminance when white voltage is applied is high, a bright and high-contrast display device can be obtained. The liquid crystal material to be used is not particularly limited, but in an aspect in which an electric field is applied between the upper and lower substrates 6 and 8, a liquid crystal material having a positive dielectric anisotropy is used so that liquid crystal molecules respond in parallel to the electric field direction. To do.

  For example, when the liquid crystal cell 131 is an OCB mode liquid crystal cell, a nematic liquid crystal having a positive dielectric anisotropy between Δn = 0.08 and Δε = 5 between the upper substrate 133 and the lower substrate 134. A material etc. can be used. The thickness d of the liquid crystal layer 132 is not particularly limited, but can be set to about 6 μm when a liquid crystal having the above characteristics is used. In order to obtain sufficient brightness when white voltage is applied, the brightness during white display changes depending on the thickness Δ and the product Δn · d of refractive index anisotropy Δn when white voltage is applied. The Δn · d of the liquid crystal layer in the non-application state is preferably set to be in the range of 0.6 to 1.5 μm.

  In addition, in the OCB mode liquid crystal display device, the addition of a chiral material generally used in the TN mode liquid crystal display device is rarely used to degrade the dynamic response characteristics, but in order to reduce alignment defects. May be added. In addition, the multi-domain structure is advantageous for adjusting the alignment of the liquid crystal molecules in the boundary region between the domains. A multi-domain structure refers to a structure in which one pixel of a liquid crystal display device is divided into a plurality of regions. For example, in the OCB mode, a multi-domain structure is preferable because the viewing angle characteristics of luminance and color tone are improved. Specifically, each pixel is composed of two or more (preferably 4 or 8) regions in which the initial alignment state of the liquid crystal molecules is different from each other, and averaging is performed. Can be reduced. Further, the same effect can be obtained even if each pixel is constituted by two or more different regions where the alignment direction of liquid crystal molecules continuously changes in a voltage application state.

  The transparent films 141 and 142 have optical characteristics in which the wavelength dependency of the in-plane retardation and the wavelength dependency of the thickness direction retardation satisfy a specific relationship. The transparent films 141 and 142 may function as a support for the optically anisotropic layers 144 and 145, may function as a protective film for the polarizing films 137 and 138, or both functions. You may have. That is, the polarizing film 137, the transparent film 141, and the optically anisotropic layer 144, or the polarizing film 138, the transparent film 142, and the optically anisotropic layer 145 are incorporated into the liquid crystal display device as a laminated body. They may be incorporated as individual members. In addition, a configuration may be employed in which a protective film for a polarizing film is separately disposed between at least one of the transparent film 141 and the polarizing film 137 and between the transparent film 142 and the polarizing film 138. The protective film is preferably not arranged. The slow axis 141x of the transparent film 141 and the slow axis 142x of the transparent film 142 are preferably substantially parallel or orthogonal to each other. If the slow axis 141x and the slow axis 142x are orthogonal to each other, the optical properties of light perpendicularly incident on the liquid crystal display device are deteriorated by canceling the birefringence of the transparent films 141 and 142 to each other. Can be reduced. Further, in the aspect in which the slow axis 141x and the slow axis 142x are parallel to each other, when the liquid crystal layer has a residual phase difference, the phase difference can be compensated by the birefringence of the protective film.

  Regarding the transmission axes 137x and 138x of the polarizing films 137 and 138, the slow axis directions 141x and 142x of the transparent films 141 and 142, and the alignment direction of the liquid crystal molecules, the materials used for each member, the display mode, and the lamination of the members Adjust to the optimum range according to the structure. That is, the transmission axis 137x of the polarizing film 137 and the transmission axis 138x of the polarizing film 138 are arranged so as to be substantially orthogonal to each other. However, in the present invention, the liquid crystal display device is not limited to the structure shown here.

  The optically anisotropic layers 144 and 145 are disposed between the transparent films 141 and 142 and the liquid crystal cell 131. The optically anisotropic layers 144 and 145 are layers formed from a composition containing a liquid crystal compound, for example, a rod-like compound or a discotic compound. In the optically anisotropic layers 144 and 145, the molecules of the liquid crystal compound are fixed in a predetermined alignment state. The molecular symmetry axis of the liquid crystalline compound in the optically anisotropic layers 144, 145, the orientation average direction 144x, 145x at least at the interface on the transparent film 141, 142 side, and the slow axis 141x in the plane of the transparent film 141, 142 , 142x intersect with each other at approximately 45 °. When arranged in such a relationship, the optically anisotropic layers 144 and 145 cause retardation with respect to the incident light from the normal direction, so that light leakage does not occur and the incident light from the oblique direction is not incident. In contrast, the effects of the present invention can be sufficiently achieved. Even at the interface on the liquid crystal cell 131 side, the average direction of the molecular symmetry axes of the optically anisotropic layers 144 and 145 is such that the slow axes 141x and 142x in the plane of the transparent films 141 and 142 are approximately 45 °. preferable. In addition, the alignment average direction 144x on the polarizing film 137 side (transparent film interface side) of the molecular symmetry axis of the liquid crystalline compound of the optically anisotropic layer 144 is approximately 45 ° with respect to the transmission axis 137x of the polarizing film 137 located closer to the optically anisotropic layer 144. It is preferable to do. Similarly, the orientation average direction 145x on the polarizing film side (transparent film interface side) of the molecular symmetry axis of the liquid crystalline compound of the optically anisotropic layer 145 is approximately 45 degrees with the transmission axis 138x of the polarizing film 138 located closer. It is preferable that When arranged in this relationship, optical switching can be performed according to the sum of the retardation generated in the optically anisotropic layer 144 or the optically anisotropic layer 145 and the retardation generated in the liquid crystal layer, and from an oblique direction. The effect of the present invention can be sufficiently exerted with respect to the incident light.

(HAN type liquid crystal display device)
The polymer film of the present invention may be used as a support for a retardation plate of a HAN type liquid crystal display device having a HAN mode liquid crystal cell. In the retardation plate used in the HAN type liquid crystal display device, it is preferable that the direction in which the absolute value of retardation is minimum does not exist in the plane of the retardation plate and in the normal direction. The optical properties of the retardation plate used in the HAN type liquid crystal display device are also determined by the optical properties of the optically anisotropic layer, the optical properties of the support, and the arrangement of the optically anisotropic layer and the support. . A retardation plate used in a HAN type liquid crystal display device is described in JP-A-9-197397. Moreover, it is described in a paper by Mori et al. (Jpn. J. Appl. Phys. Vol. 38 (1999) p. 2837).

(Reflective liquid crystal display)
The transparent polymer film of the present invention is also advantageously used as a retardation plate of a TN type, STN type, HAN type, or GH (Guest-Host) type reflective liquid crystal display device. These display modes have been well known since ancient times. The TN-type reflective liquid crystal display device is described in JP-A-10-123478, International Publication WO98 / 48320, and Japanese Patent No. 3022477. The optical compensation sheet used in the reflective liquid crystal display device is described in International Publication No. WO 00/65384.

(Other liquid crystal display devices)
The transparent polymer film of the present invention is also advantageously used as a support for an optical compensation sheet of an ASM type liquid crystal display device having a liquid crystal cell in an ASM (Axial Symmetrical Aligned Microcell) mode. The ASM mode liquid crystal cell is characterized in that the thickness of the cell is maintained by a resin spacer whose position can be adjusted. Other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device are described in Kume et al. (Kume et al., SID 98 Digest 1089 (1998)).

(Hard coat film, antiglare film, antireflection film)
The transparent polymer film of the present invention may be applied to a hard coat film, an antiglare film and an antireflection film depending on circumstances. For the purpose of improving the visibility of flat panel displays such as LCD, PDP, CRT, EL, etc., any or all of a hard coat layer, an antiglare layer and an antireflection layer are provided on one or both sides of the transparent polymer film of the present invention. can do. Preferred embodiments of such an antiglare film and antireflection film are described in detail in pages 54 to 57 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). It can be preferably used in the transparent polymer film of the present invention.

[Experiment 1]
A polymer solution was prepared by the process shown in FIG. 1 using the polymer solution preparation apparatus 30 shown in FIG. Details are as follows. The following solvent A is gradually added to the first tank 31 made of stainless steel having a capacity of 400 liters while mixing at the following mixing ratio, and various additives having the following mixing ratio are added while adding the polymer A. The mixture was charged to a total of 300 kg, and the mixture was stirred.

The stirring shear rate in the first tank 31 is initially stirred at a peripheral speed of 15 m / sec (shear stress 5 × 10 ⁵ N / m ² ), and then the peripheral speed 1 m / sec (shear stress 1 × 10 ⁵ N / m). ² ) and stirred for 30 minutes. The temperature at the start of stirring was 25 ° C., and the final temperature reached 35 ° C. by using cooling water controlled to a predetermined temperature as the heat transfer medium 51. After completion of the stirring, the high-speed stirring was stopped, the peripheral speed of the stirring blade 46b was set to 0.5 m / second, and stirring was further performed for 100 minutes to swell the polymer A.

(Solid content)
Polymer A (cellulose triacetate: substitution degree 2.91, viscosity average polymerization degree 270, 6-position, acetyl group substitution degree 0.93, acetone extraction 7% by mass, weight average molecular weight / number average molecular weight ratio 2.3, Tg160 ° C, water content 0.2 mass%, 6 mass% viscosity in dichloromethane solution 305 mPa · s, residual acetic acid content 0.1 mass% or less, Ca content 65 ppm, Mg26 ppm, iron 0.8 ppm, sulfate ion 18 ppm, yellow Index 1.9, free acetic acid 47ppm, average particle size 1.5mm, powder with standard deviation 0.5mm) 20 parts by mass plasticizer A (triphenyl phosphate) 1.6 parts by mass plasticizer B (biphenyl) Diphenyl phosphate) 0.8 parts by mass / degradation inhibitor A (2,6-di-t-butyl-4-methylphenol) 0.2 parts by mass / UV Agent A (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine 0.2 parts by mass / UV agent B ( 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole) 0.2 part by mass / UV agent C (2 (2′-hydroxy-3 ′, 5′- Di-tert-amylphenyl) -5-chlorobenzotriazole 0.2 parts by mass / fine particles (silicon dioxide (particle size 20 nm), Mohs hardness about 7) 0.05 part by mass / citric acid ethyl ester (monoester: diester = 1: 1) 0.04 parts by mass (solvent)
-Dichloromethane 80.0 parts by mass-Methanol 10.0 parts by mass-Butanol 5.0 parts by mass All solvents, dichloromethane, butanol, methanol, and ethanol, whose water content is 0.2% by mass or less are used. did. Moreover, it was confirmed that the water content in the mixture was 0.2% by mass or less.

  The obtained heterogeneous gel-like mixture is fed with a screw pump whose center part is heated to 30 ° C., and cooled by a heat transfer medium from the outer periphery of the screw to −75 ° C. for 3 minutes. The cooling part was passed through. The heat transfer medium was implemented using the -80 degreeC refrigerant | coolant cooled with the refrigerator. The mixed liquid obtained by cooling was heated to 35 ° C. while being sent by a screw pump and sent to the second tank 36 made of stainless steel. After stirring at 50 ° C. for 2 hours to obtain a homogeneous solution, the solution was filtered through the first and second filters 37 and 38. The filter of the first filter 37 is a filter paper having an absolute filtration accuracy of 0.01 mm (# 63) manufactured by Toyo Filter Paper Co., Ltd., and the filter of the second filter 38 is a filter paper having an absolute filtration accuracy of 2.5 μm (manufactured by Pall). FH025). The obtained mixture is heated to 110 ° C. and 1 MPa by the pressure heating unit 41 of the liquid feeding pipe, and discharged into a container having a normal pressure to volatilize a predetermined amount of the organic solvent, and the second cooling unit 42 To obtain a polymer solution having a temperature of 40 ° C.

  Next, the above-mentioned 40 ° C. plastic solution was cast on a mirror surface stainless steel support, which is a drum 86 having a diameter of 3 m, by using a casting film forming apparatus 70 shown in FIG. The surface temperature of the drum 86 was set to −5 ° C. The Gieser used was similar to that described in JP-A-11-314233. The casting speed was 10 m / min and the casting width was 200 cm. The internal temperature of the casting apparatus 43 was set to 15 ° C. Then, the film 87 was peeled 50 cm before the casting start position on the drum 86, and both ends of the film 87 were held in the tenter device 77. The film 87 was conveyed to the roller drying device 81. In this drying, first, a drying air of 45 ° C. was blown, and further dried at 110 ° C. for 5 minutes and further at 145 ° C. for 10 minutes, and the film temperature at this time was about 140 ° C. The thickness of the obtained film 87 is 80 μm. The obtained sample was cut by 3 cm on both side edges, further provided with a roughness of 100 μm in height from 2 to 10 mm from both edges, wound into a roll, and the retardation value of this film 87 was measured. . The results of this experiment are shown in Table 1. In Table 1, the unit of each numerical value is nm.

[Experiment 2]
The same operation as in Experiment 1 was performed except that the obtained film 87 was stretched as follows. The obtained film 87 was subjected to longitudinal uniaxial stretching using a roll stretching machine. The roll of the roll drawing machine was an induction heating jacket roll having a mirror-finished surface, and the temperature of each roll could be adjusted individually. The stretching zone was covered with a casing at 130 ° C. The roll before the stretching part was set so that it could be gradually heated to 130 ° C. The inter-stretching distance was adjusted so that the L / W ratio, which is the ratio of the inter-roll distance (L) and the film width (W) of the retardation plate, was 2.5. After stretching, the film was cooled and wound up. When the draw ratio was measured, it was 1.15 times. The film thickness was 80 μm. The results of this experiment are shown in Table 1.

[Experiment 3]
The experiment was performed in the same manner as in Experiment 1 except that plasticizer A and plasticizer B were not added. The results of this experiment are shown in Table 1.

[Experiment 4]
The experiment was performed in the same manner as in Experiment 2 except that plasticizer A and plasticizer B were not added. The results of this experiment are shown in Table 1.

[Experiment 5]
The experiment was performed in the same manner as in Experiment 1 except that the plasticizer A and the plasticizer B in Experiment 1 were replaced with 2.4 parts by mass of the plasticizer C (triphenylmethanol). The results of this experiment are shown in Table 1.

[Experiment 6]
Experiment 2 was conducted except that plasticizer A and plasticizer B were replaced with 2.4 parts by mass of plasticizer C (triphenylmethanol). The results of this experiment are shown in Table 1.

[Experiment 7]
The experiment was performed in the same manner as in Experiment 1 except that the solvent was changed to a mixture of 92.0 parts by mass of dichloromethane and 8.0 parts by mass of methanol. The results of this experiment are shown in Table 1.

[Experiment 8]
The experiment was performed in the same manner as in Experiment 2 except that the solvent was changed to a mixture of 92.0 parts by mass of dichloromethane and 8.0 parts by mass of methanol. The results of this experiment are shown in Table 1.

[Experiment 9]
Experiment A was conducted in the same manner as in Experiment 1 except that the polymer A was replaced with the polymer B (cellulose triacetate; substitution degree 2.92, viscosity average polymerization degree 300, 6-position acetyl group substitution degree 0.94). The results of this experiment are shown in Table 1.

[Experiment 10]
Experiment A was conducted in the same manner as in Experiment 2 except that polymer A was replaced with polymer B (cellulose triacetate; substitution degree 2.92, viscosity average polymerization degree 300, 6-position acetyl group substitution degree 0.94). The results of this experiment are shown in Table 1.

[Comparative Experiment 1]
Experiment A was carried out in the same manner as in Experiment 1 except that the polymer A was changed to polymer C (cellulose triacetate; substitution degree 2.86, viscosity average polymerization degree 310, 6-position acetyl group substitution degree 0.89). The results of this experiment are shown in Table 1.

[Comparison experiment 2]
The same procedure as in Experiment 2 was performed except that the polymer A in Experiment 2 was changed to the polymer C. The results of this experiment are shown in Table 1.

[Comparative Experiment 3]
Polymer A in Experiment 1 was replaced with polymer D (cellulose triacetate; substitution degree 2.79, viscosity average polymerization degree 310, 6-position acetyl group substitution degree 0.90), and the solvent was methyl acetate (64.8 parts by mass), The experiment was performed in the same manner as in Experiment 1 except that a mixture of acetone (6.4 parts by mass), ethanol (6.4 parts by mass), and butanol (3.2 parts by mass) was used. The results of this experiment are shown in Table 1.

[Comparison Experiment 4]
Polymer A was changed to Polymer D, and the solvent was a mixture of methyl acetate (64.8 parts by mass), acetone (6.4 parts by mass), ethanol (6.4 parts by mass), butanol (3.2 parts by mass). The experiment was carried out in the same manner as in Experiment 2, except that The results of this experiment are shown in Table 1.

[Comparative Experiment 5]
Polymer A, Polymer E (Polycarbonate; Polycarbonate copolymer in which bisphenol A and 9,9-bis (4-hydroxy-3-methylphenyl) fluorene are used as bisphenol components, and these are introduced at a molar ratio of 1/1) The experiment was conducted in the same manner as in Experiment 1 except that the solvent was changed to dichloromethane (100.0 parts by mass). The results of this experiment are shown in Table 1.

[Comparative Experiment 6]
The polymer A is changed to the polymer E, the solvent is changed to dichloromethane (100.0 parts by mass), the solvent content in the film before stretching is further adjusted to 2% by mass with respect to the polymer E, and the stretching temperature is 218 ° C. The experiment was performed in the same manner as in Experiment 2 except that the L / W ratio was 1.2 and the draw ratio was changed to 1.3 times. The results of this experiment are shown in Table 1.

[Comparative Experiment 7]
The experiment was performed in the same manner as in Experiment 1 except that the polymer A was changed to the polymer F (polycarbonate; a polycarbonate homopolymer containing only bisphenol A as a bisphenol component) and the solvent was changed to dichloromethane (100.0 parts by mass). The results of this experiment are shown in Table 1.

  From the results shown in Table 1, in the films obtained in Experiments 1 to 10, ΔRe and ΔRth have opposite signs, ΔRth is a positive value, and ΔRe is a negative value. And it turns out that any film obtained in Experiments 1 to 10 has a | ΔRth | of 10 nm or more and 1000 nm or less. On the other hand, it can be seen that ΔRe and ΔRth have the same sign in the films obtained in Comparative Experiments 1-7. Moreover, in order to obtain the film which has the optical characteristic of Experiment 1-10, it turns out that the manufacturing method of the polymer solution of this invention is effective.

[Experiment 11]
The film obtained in Experiment 2 was passed through a dielectric heating roll having a temperature of 60 ° C. and heated to a film surface temperature of 40 ° C., and then an alkali solution (S-1) having the following composition was applied with a rod coater. The amount was 15 ml / m ² . Then, after being allowed to stay for 15 seconds under a steam far-infrared heater manufactured by Noritake Company Limited heated to 110 ° C., 3 ml / m ^{2 of} pure water was applied using the same rod coater. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then, the film was retained in a drying zone at 70 ° C. for 5 seconds and dried.

<Alkaline solution (S-1) composition>
Potassium hydroxide 8.55% by mass
23.235% by weight of water
Isopropanol 54.20% by mass
Surfactant _{(K-1; C 14 H} 29 O (CH 2 CH 2 O) 20 H) 1.0 wt%
Propylene glycol 13.0% by mass
Antifoaming agent Surfinol DF110D (manufactured by Nissin Chemical Industry Co., Ltd.) 0.015% by mass

Next, the rubbing process was implemented in the longitudinal direction of the saponified film. On this surface-treated film, an alignment film coating solution having the following composition was coated with a load coater at a coating amount of 28 ml / m ² . The film was dried with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds.
<Alignment film coating solution>
Modified polyvinyl alcohol represented by Chemical formula 20 20 parts by weight Water 360 parts by weight Methanol 120 parts by weight Glutaraldehyde 0.5 parts by weight

(Formation of optically anisotropic layer)
A discotic liquid crystal coating solution (DA-1) having the following composition is applied with a # 4 wire bar coater, heated in a high-temperature bath at 125 ° C. for 3 minutes to orient the discotic liquid crystalline molecules, and then subjected to high pressure. An optical compensation sheet (KS-1) was prepared by irradiating UV with 500 mJ / cm ² using a mercury lamp and allowing to cool to room temperature.

<Discotic liquid crystal coating solution (DA-1)>
9.1 parts by mass of discotic liquid crystal DLC-A represented by Chemical Formula 37 Ethylene oxide-modified trimethylolpropane acrylate
(V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 0.9 parts by mass Cellulose acetate butyrate (CAB551-0.2 manufactured by Eastman Chemical) 0.2 parts by mass Cellulose acetate butyrate (CAB531-1 manufactured by Eastman Chemical) ) 0.05 parts by mass Irgacure 907 3.0 parts by mass Kayacure DETX (manufactured by Nippon Kayaku Co., Ltd.) 0.1 parts by mass Citric acid half ester (organic acid (A-1) represented by Chemical formula 38) 1.0 Part by weight methyl ethyl ketone 25.9 parts by weight

  The tilt angle was measured by applying the crystal rotation method. As a result, in the discotic liquid crystal molecule, the angle (tilt angle) formed by the disc surface and the glass substrate plane increases from 3 degrees to 80 degrees from the film surface toward the optical air interface (hybrid orientation), and the average tilt angle Was found to be hybrid-oriented at about 40 degrees. The thickness of the optically anisotropic layer was 1.8 μm.

[Experiment 2-1]
An aqueous solution with an iodine concentration of 0.3 g / liter and potassium iodide of 18.0 g / liter was set at 25 ° C., and a polyvinyl alcohol film (thickness manufactured by Kuraray Co., Ltd.) having a film thickness of 75 μm was immersed therein. Piled up. Furthermore, this film was stretched 5.0 times in an aqueous solution at 50 ° C. with a boric acid concentration of 80 g / liter and a potassium iodide concentration of 30 g / liter to obtain a polarizing film. The polymer films obtained in Experiments 1 to 11 of Example 1 were each treated with a 1.5N sodium hydroxide (NaOH) aqueous solution at 50 ° C. for about 180 seconds, neutralized, and then washed with water. , And bonded to the front and back of the polarizing film. A 4% aqueous solution of polyvinyl alcohol (trade name; PVA-117H, manufactured by Kuraray Co., Ltd.) was used as the adhesive. This was dried in an air constant temperature bath at 80 ° C. for about 30 minutes to obtain a polarizing plate.

With the spectrophotometer, the parallel transmittance Yp and the orthogonal transmittance Yc in the visible region were determined for the obtained polarizing plate, and the polarization degree PY was determined based on the following equation.
PY = {(Yp−Yc) / (Yp + Yc)} ^1/2 × 100 (%)

  As a result of this experiment 2-1, in any of the polarizing plates constructed using the films produced in the experiments 1 to 10, the degree of polarization PY is 99.6% or more, and there is no unevenness. It turns out that the obtained film can be used suitably for a polarizing plate.

[Experiment 2-2]
The polymer films obtained in Experiments 1 to 11 of Example 1 were saponified under any of the following conditions.
(1) Coating saponification 20 parts by weight of water was added to 80 parts by weight of iso-propanol, KOH was dissolved to 1.5 N in this, and the resulting solution was adjusted to 60 ° C. and used as a saponification solution. This solution was applied to a polymer film at 60 ° C. at 10 g / m ² and saponified for 1 minute. Thereafter, hot water at 50 ° C. was sprayed for 1 minute at a rate of 10 l / m ² · min with a spray.
(2) Immersion saponification A 1.5 N aqueous solution of NaOH was used as a saponification solution. This liquid was adjusted to 60 ° C., and the polymer film was immersed for 2 minutes. Thereafter, it was immersed in a 0.1N aqueous sulfuric acid solution for 30 seconds and then passed through a water-washing bath.

Among the cellulose triacetate films subjected to saponification treatment, a polarizing layer having a thickness of 20 μm is prepared by giving a peripheral speed difference between two pairs of nip rolls according to Example 1 described in JP-A-2001-141926, and stretching in the longitudinal direction. After the polarizing layer is sandwiched between these two films, an absorption axis and a slow axis of the film are 90 degrees with PVA (PVA-117H manufactured by Kuraray Co., Ltd.) 3% aqueous solution as an adhesive. They were pasted together so that
This was dried in an air constant temperature bath at 80 ° C. for about 30 minutes to obtain a polarizing plate.

  About the polarizing plate obtained by this experiment 2-2, the polarization degree was measured similarly to experiment 2-1. As a result, in any polarizing plate constructed using the films produced in Experiments 1 to 12, the degree of polarization PY is 99.6% or more, and there is no unevenness. It turns out that it can use suitably for a polarizing plate.

  The film obtained in Experiments 1 to 10 of Example 1 was evaluated as a retardation plate. After cutting the film into a predetermined size to form a sheet, for each of the sheet-like films, Re and Rth were measured at any plurality of locations, and the sheet-like film was further heat treated at 100 ° C. for 24 hours. Changes in values of Re and Rth were measured.

  In the obtained sheet-like film, each variation in Re and Rth was ± 2 nm, and changes in Re and Rth before and after the heat treatment were both in the range of ± 5 nm. Therefore, it turns out that the film obtained by this invention can be used suitably for a phase difference plate.

[Experiment 4-1]
The viewing side polarizing plate of the liquid crystal display device of the notebook computer on which the transmission type TN liquid crystal display device was mounted was replaced with the polarizing plate produced in Experiment 2 to obtain a liquid crystal display device. In addition, this liquid crystal display device has the polarization separation film (brand name; D-BEF, Sumitomo 3M Co., Ltd. product) which has a polarization selection layer between the backlight and a liquid crystal cell.

  The liquid crystal display device obtained in Example 4-1 had no unevenness in brightness and had a very high display quality. Furthermore, the liquid crystal display device obtained in Example 4-1 has less change in color regardless of the viewing angle compared to the liquid crystal display device before being attached to the polarizing plate prepared in Experiment 2. It was. This shows that the film obtained by the solution casting method of the present invention is suitable as a liquid crystal display device.

[Experiment 4-2]
A liquid crystal display device having the same configuration as that shown in FIG. 4 was produced. From the observation direction (top), the upper polarizing plate (protective film (Fujitac TD80UL, manufactured by Fuji Photo Film Co., Ltd., not shown) and the polarizing film 102), optical compensation film 106 (protective film 108 in FIG. 4) A liquid crystal cell (a combination of the upper substrate 111 and a liquid crystal layer including the liquid crystal molecules 113 and the lower substrate 112), an optical compensation film 107 (also serving as the protective film 109), a lower polarizing plate ( A protective film (Fujitac TD80UL, manufactured by Fuji Photo Film Co., Ltd., not shown) 103 was laminated, and a backlight light source (not shown) was further disposed. Note that, as the optical compensation film 106 and the optical compensation film 107, the films of Experiment 2, Experiment 4, and Experiment 8 of Example 1 were used, and polarizing plates were formed in the same manner as in Example 2 to produce panels.

  In the liquid crystal cell 101, the cell gap between the substrates 111 and 112 is 3.6 μm, and a liquid crystal material 113 having negative dielectric anisotropy (“MLC6608”, manufactured by Merck & Co., Inc.) is dropped between the substrates and sealed. A liquid crystal layer was formed between the substrates 111 and 112. The retardation of the liquid crystal layer (that is, the product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn) was set to 300 nm. As the liquid crystal material, an alignment film (“JALS-2021-R1”, manufactured by JSR) was applied to a substrate, and the liquid crystal was vertically aligned. In this way, a VA mode liquid crystal cell was produced.

  The leakage light of the liquid crystal display device thus manufactured was measured. The black display transmittance (%) at an azimuth angle of 45 ° and a polar angle of 60 ° viewing angle is 0.020 or less, and the color deviation Δxy from the front is 0.15. The following performance was good. In contrast, when the film obtained in Comparative Experiments 1 to 4 of Example 1 or a commercially available tack film (Fujitac TD80UL, manufactured by Fuji Photo Film) is used, the color shift Δxy from the front exceeds 0.15. It was found that the performance was inferior. Further, when the film obtained in Comparative Experiments 5 to 7 of Example 1 was corona-treated and bonded to the polarizing film, and the same evaluation was performed, the color deviation Δxy from the front exceeded 0.3. It was found that the performance was inferior.

[Experiment 4-3]
A liquid crystal display device having the same configuration as that shown in FIG. 5 was produced. From the observation direction (top), the upper polarizing plate (protective film (Fujitac TD80UL, manufactured by Fuji Photo Film, not shown) and polarizing film 137), optical anisotropic layer 144 (polymer film as protective film) 141 as an optical compensation film, liquid crystal cell 131 (upper substrate 133, liquid crystal layer 132, lower substrate 134), and optical anisotropic layer 145 (also serves as a polymer film 142 as a protective film). And a lower polarizing plate 138 (protective film (Fujitac TD80UL, manufactured by Fuji Photo Film, not shown)) and a backlight light source (not shown) were further arranged. In addition, as the optical compensation film 144 and the optical compensation film 145, the film of Experiment 11 of Example 1 was used, respectively, and the polarizing plate was formed similarly to Experiment 2-1, and the panel was produced. At this time, the film was disposed so that the surface opposite to the surface on which the optically anisotropic layer was formed was adjacent to the polarizing film.

  In the liquid crystal cell 131, a cell gap between the substrates 133 and 134 is set to 6 μm, and a liquid crystal compound (ZLI1132, manufactured by Merck & Co., Inc.) having Δn (difference between the refractive index ne and no) of 0.1396 is injected between the substrates. Thus, a bend-aligned liquid crystal cell was produced. As the substrates 133 and 134, a glass substrate with an ITO electrode provided with a polyimide film as an alignment film and subjected to a rubbing treatment on the alignment film, the rubbing directions of the two glass substrates are arranged in parallel. Used face to face. The size of the liquid crystal cell was 20 inches.

  The leakage light of the liquid crystal display device thus manufactured was measured. The black display transmittance (%) at an azimuth angle of 45 ° and a polar angle of 60 ° viewing angle is 0.025 or less, and the color deviation Δxy from the front is 0.15. The following performance was good. In contrast, when the film obtained in Comparative Experiments 1 to 4 of Example 1 or a commercially available tack film (Fujitac TD80UL, manufactured by Fuji Photo Film) is used, the color shift Δxy from the front exceeds 0.15. It was found that the performance was inferior. Moreover, when the film obtained by corona-treating the film obtained in Comparative Experiments 5 to 7 of Example 1 was used, variation in retardation of the film after forming the optically anisotropic layer became severe.

  As described above, according to the method for producing a polymer film and a polymer solution and a polarizing plate of the present invention, the liquid crystal cell is optically compensated accurately, has a high contrast, and is colored depending on the visual direction during black display. A reduced liquid crystal display device, in particular, a VA mode, OCB mode, or IPS mode liquid crystal display device can be obtained. In addition, according to the present invention, optical compensation for optically compensating liquid crystal cells, particularly VA mode, OCB mode, and IPS mode liquid crystal cells, which contributes to improvement of contrast and reduction of coloring depending on the visual direction during black display. A film can be obtained.

It is process drawing of polymer solution preparation which implemented this invention. It is the schematic of the polymer solution preparation apparatus which implemented this invention. It is the schematic of solution casting apparatus. It is the schematic of the liquid crystal display device using the polymer film of this invention. It is the schematic of the liquid crystal display device using the polymer film of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Swelling process 12 1st cooling process 13 Heating process 16 Pressure heating process 17 2nd cooling process 23 Polymer solution 30 Polymer solution preparation apparatus 31 1st tank 32 1st cooling part 32a Pressure controller 35 Heating part 41 Pressure heating part 42 Second cooling section 70 Solution casting equipment

Claims (13)

  When the in-plane retardation value when the measurement wavelength is n (unit: nm) is Re (n) and the thickness direction retardation value is Rth (n), it is calculated by Re (700) -Re (400). A polymer film, wherein either one of ΔRe and ΔRth obtained by Rth (700) −Rth (400) is a positive value and the other is a negative value.   The polymer film according to claim 1, which has a single-layer structure.   The polymer film according to claim 1, wherein the ΔRth satisfies 10 nm ≦ | ΔRth | ≦ 1000 nm.   The polymer film according to claim 1, wherein the ΔRe is a negative value.   The polymer film according to any one of claims 1 to 4, wherein the polymer as a main component of the polymer film is cellulose acylate.   6. The polymer film according to claim 5, wherein the cellulose acylate has an acyl group substitution degree of 2.87 or more.   The liquid crystal display device having a liquid crystal cell provided between a pair of alignment films and a phase difference plate provided on the side opposite to the liquid crystal cell of the alignment film is used as the phase difference plate. Item 7. The polymer film according to any one of Items 1 to 6. In a polarizing plate having protective films on both sides of the polarizing film,
A polarizing plate, wherein at least one of the protective films is a polymer film according to any one of claims 1 to 7. In a method of preparing a polymer solution from a mixture comprising a polymer and a solvent,
A swelling step of swelling the polymer with the solvent at a temperature of −10 ° C. to 50 ° C.
A cooling step of cooling the mixture after the swelling step;
A heating step of heating the mixture after the cooling step;
Have
The temperature by the cooling step is lower than the temperature in the swelling step, and −100 ° C. or more and −10 ° C. or less,
A method for preparing a polymer solution, wherein the temperature in the heating step is 0 ° C. or more and 57 ° C. or less.   The method for preparing a polymer solution according to claim 9, wherein the mixture is cooled under pressure in the cooling step.   The method for preparing a polymer solution according to claim 9 or 10, wherein a main component of the solvent is a chlorinated organic solvent.   The method for preparing a polymer solution according to any one of claims 9 to 11, wherein a main component of the polymer is cellulose acylate.   The method for preparing a polymer solution according to claim 12, wherein the cellulose acylate has an acyl group substitution degree of 2.87 or more.