JP5488258B2 - Method for producing optical compensation film - Google Patents

Description

  The present invention relates to a method for producing an optical compensation film (hereinafter also simply referred to as a production method).

  With the development of multimedia such as personal computers, color liquid crystal displays have become common in laptop personal computers. In laptop computers, STN liquid crystal displays and TFT liquid crystal displays are mainly used. In recent years, liquid crystal displays have been increased in size, and advanced improvement in viewing angle characteristics has been demanded. Therefore, an optical compensation film (also referred to as an optical anisotropic body) having high compensation performance is desired.

  Since the STN liquid crystal display is a display element using a birefringence mode, it has a big problem that it is colored by a phase difference generated in the liquid crystal and cannot be displayed in black and white or in color. In order to solve such a problem, a D-STN method (a method using a liquid crystal cell for compensation) has been tried. However, in this method, in terms of “thin and light” which is a characteristic of a liquid crystal display, The manufacturing process of the compensation liquid crystal cell requires a high accuracy and has a problem in that the yield is poor.

  As a method for solving these problems, various proposals have been made. For example, Japanese Patent Laid-Open No. 63-149624 proposes an F-STN method using a stretched resin film, and also provides compensation performance of the D-STN method. In order to maintain and reduce the mass and thickness, a method has been proposed in which color compensation is performed using a film in which a liquid crystalline polymer is twisted and aligned (see, for example, Patent Documents 1 and 2).

  The retardation compensation plate of this liquid crystal display is composed of a translucent substrate, an alignment film formed on the substrate, and a liquid crystal polymer layer fixed in a twisted alignment state on the alignment film. .

  Furthermore, recently, as a viewing angle compensation of a TFT-TN liquid crystal display, an attempt has been made to improve the viewing angle characteristics of the liquid crystal cell by disposing a discotic liquid crystal film on the upper and lower surfaces of the liquid crystal cell (for example, (See Patent Document 3).

  The TN type liquid crystal display compensation film is an optically substantially isotropic resin film, similar to the phase difference compensation plate of the liquid crystal display described in JP-A-3-87720 and JP-A-4-333919. It is composed of an optically anisotropic layer on which a liquid crystal compound is aligned.

  However, in order to produce an optical compensation film by orienting a liquid crystal compound after coating a liquid crystal layer containing a liquid crystal compound on a resin film, particularly on a long support, problems specific to liquid crystal, particularly unevenness and defects As a result, the productivity is low and the cost is high.

JP-A-3-87720 Japanese Patent Laid-Open No. 4-333019 Japanese Patent Laid-Open No. 7-191217

  An object of the present invention is to provide a method for producing an optical compensation film that is free from unevenness and variation, exhibits good contrast, and has high productivity.

  The above object of the present invention has been achieved by the following constitution.

  1. In a method for producing an optical compensation film, in which a coating liquid containing a solvent and a liquid crystal compound is continuously coated on a long support to coat a liquid crystal layer, the temperature of the coating liquid is 15 ° C. to 30 ° C. A method for producing an optical compensation film, wherein the temperature is adjusted to 15 ° C. to 30 ° C. and the coating environment temperature is adjusted to 20 to 30 ° C.

  2. After coating the liquid crystal layer on the long support, the temperature of the liquid crystalline compound in the liquid crystal layer is higher than the temperature (T-IN) from the isotropic phase to the nematic phase, and from the nematic phase to the isotropic phase. The method for producing an optical compensation film as described in 1 above, comprising a step of irradiating active energy rays while maintaining the temperature (T-NI) or lower.

  3. 3. The method for producing an optical compensation film as described in 2 above, which comprises a step of irradiating active energy rays under an oxygen concentration of 2% or less.

  4). After the liquid crystal layer is coated on the long support, the polarizing plate is arranged so as to be crossed Nicol, and the long support is passed between the polarizing plates, and the transmitted light is used while being conveyed. 4. The method for producing an optical compensation film according to any one of 1 to 3 above, further comprising a step of monitoring a state of unevenness.

  5. 5. The method for producing an optical compensation film according to any one of 1 to 4, wherein the surface potential of the long support is adjusted to −5 to +5 kV at the time of application of the coating liquid containing a liquid crystalline compound.

  According to the present invention, it was possible to provide a method for producing an optical compensation film that is free from unevenness and variation, exhibits good contrast, and has high productivity.

It is the schematic which shows an example of arrangement | positioning with the ventilation port and web in a drying apparatus. (A) is the schematic which shows an example of arrangement | positioning of the ventilation opening and web in a drying apparatus, (b) is the schematic which shows an example of the shape adjustment board of an ventilation opening. It is the schematic which shows the web conveyed on a metal belt in a drying zone. It is the schematic which shows the web conveyed on a metal plate in a drying zone. It is the schematic which shows the process of drying a web using a some drying zone.

  In the method for producing an optical compensation film of the present invention, by having the configuration according to any one of claims 1 to 5, there is no unevenness or variation, a good contrast is exhibited, and high productivity is achieved. A method for producing a compensation film could be provided.

  Hereafter, the detail of the manufacturing method of the optical compensation film of this invention is demonstrated sequentially.

  The optically anisotropic layer according to the present invention will be described.

  The optically anisotropic layer according to the present invention is a layer containing an optically anisotropic compound formed by fixing the alignment of a liquid crystalline compound, and the liquid crystalline compound is an alignment layer adjacent to the liquid crystal layer. It is a layer containing an optically anisotropic compound that is regulated in a specific orientation direction and then fixed in the oriented state by a temperature difference or a chemical reaction.

  The optical compensation film of the present invention includes the optically anisotropic layer and a transparent support, or is formed by including an alignment layer and / or at least one elution block layer between the optically anisotropic layer and the transparent support. Are preferably used.

  When applying a liquid crystalline compound to obtain optical anisotropy, an alignment film is placed on a transparent support, a liquid crystalline compound is applied thereon, and the liquid crystalline compound is aligned.

  Here, the material constituting the alignment layer will be described. Specific examples include the following resins and substrates, but are not limited thereto. For example, polyimide, polyamideimide, polyamide, polyetherimide, polyetheretherketone, polyetherketone, polyketonesulfide, polyethersulfone, polysulfone, polyphenylenesulfide, polyphenyleneoxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal , Polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulosic plastics, epoxy resin, phenol resin, and the like.

  After the orientation layer is applied on a long support such as a transparent resin substrate, dried and placed, an orientation layer having orientation ability can be obtained by rubbing.

  A polyimide film (preferably a fluorine atom-containing polyimide) widely used as an alignment layer for aligning liquid crystal compounds is also used as a preferable alignment film in the present invention. They can be obtained by applying polyamic acid (for example, LQ / LX series manufactured by Hitachi Chemical Co., Ltd., SE series manufactured by Nissan Chemical Co., Ltd.) on a transparent resin substrate, followed by heat treatment and rubbing.

  For the rubbing treatment, a treatment method widely used as a liquid crystal alignment treatment process of the LCD can be used. That is, a method of obtaining alignment by rubbing the surface of the alignment film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing using a cloth in which fibers having uniform length and thickness are flocked on average.

  Moreover, a photo-alignment layer is mentioned as another alignment layer. As the photo-alignment material, generally known photo-alignment materials can be used. For example, photodecomposition type, photodimerization type, photoisomerization type and the like can be mentioned. Hasegawa, Liquid Crystal, Vol. The compounds described in 3 (1), 3-16 (1999) can be used. In the present invention, in particular, a photodimerizable alignment material to which alignment is imparted by irradiation with polarized ultraviolet rays is preferably used from the viewpoint of productivity.

  Examples of the above-mentioned photodimerization type alignment material include, for example, JP-A-8-304828, JP-A-7-138308, JP-A-6-095066, JP-A-5-232473, JP-A-8-015681, JP-A-9-222605, JP-A-6-287453, JP-A-6-289374, JP-A-10-506420, JP-A-10-324690, JP-A-10-310613, and the like.

  In these methods, the alignment property can be imparted to the liquid crystalline compound by irradiating the photo-alignment layer with polarized ultraviolet rays. As the light source as the light irradiation device, an ultrahigh pressure mercury lamp, a xenon lamp, a fluorescent lamp, a laser, or the like can be used. This can be combined with a polarizer to irradiate linearly polarized light. As the irradiation apparatus, for example, an apparatus disclosed in JP-A-10-90684 can be used.

  The alignment layer is applied by a solution obtained by dissolving the alignment film material in an organic solvent by curtain coating, extrusion coating, roll coating, dip coating, spin coating, printing coating, spray coating, wire bar coating, slide coating, etc. However, the present invention is not limited to these.

  The liquid crystal compound (also referred to as liquid crystal) according to the present invention will be described.

  The liquid crystalline compound according to the present invention is not particularly limited as long as it can be aligned on the alignment layer, and the alignment can provide optical anisotropy without light scattering in the visible light region. Desired.

  When the liquid crystalline compound according to the present invention is a polymer liquid crystal, for example, Publication Nos. 2592694, 2668735, 2711585, 2660601, JP-A-10-186356, 10-206636, and 10-333134. And compounds having the structure described. Among them, those having optically positive birefringence are preferably used.

  As the liquid crystalline compound according to the present invention other than the polymer liquid crystal, a rod-shaped liquid crystalline compound is generally exemplified, and a liquid crystalline compound exhibiting optically positive birefringence is preferable, and a positive compound having an unsaturated ethylenic group is used. Birefringent liquid crystalline compounds are preferred from the viewpoint of fixing the alignment. For example, compounds having structures described in JP-A Nos. 9-281480 and 9-281814 can be used, but the invention is particularly limited to these. Not.

  The structure of the liquid crystalline compound according to the present invention is not particularly limited, but in a state where the liquid crystalline compound is aligned by a chemical reaction or a temperature difference in a state where liquid crystal molecules are aligned in order to develop optical anisotropy ( This is called an optically anisotropic compound). An alignment film as described above can be placed on a transparent resin substrate, and a liquid crystal compound can be applied thereon for orientation. The alignment treatment of the liquid crystal compound is required to be maintained at a temperature equal to or higher than the liquid crystal transition temperature, and is preferably performed at a temperature that does not change the quality of the transparent resin substrate.

  Also, when the liquid crystal layer is applied by diluting the liquid crystal compound with a solvent, the alignment treatment can be performed at a temperature not higher than the liquid crystal transition temperature of the liquid crystal compound, that is, lower than the liquid crystal transition temperature of the liquid crystal compound itself. In some cases.

  When the liquid crystalline compound according to the present invention is a liquid crystalline polymer, the chemical structure includes main chain liquid crystalline polymers such as polyester, polyimide, polyamide, polycarbonate, and polyesterimide. Further, side chain type liquid crystalline polymers such as polyacrylate, polymethacrylate, polysiloxane, polymalonate and the like can be mentioned.

  In applying the liquid crystal compound and coating the liquid crystal layer, it is important to define the dry film thickness. In order to obtain uniform effects of the liquid crystal compound and the effects described in the present invention, the liquid crystal layer is dried. Although it is essential that the film thickness is 5 μm or less, it is preferably 0.5 μm to 4 μm, and more preferably adjusted to a dry film thickness of 0.5 μm to 2.5 μm. Here, the dry film thickness may be measured by peeling off the liquid crystal layer, or may be measured from a tomographic photograph taken using an electron microscope.

  Further, it is preferable to use as little coating solvent as possible, and the relationship between the coating film thickness and the film thickness after drying is such that the value of coating film thickness / dry film thickness (also referred to as film thickness after drying) is 3 to 40. Is preferable in terms of the orientation of the liquid crystalline compound and the uniform coating property, and more preferably the coating film thickness / the film thickness after drying is 5 to 20.

  As a coating method of the liquid crystal layer, a general coating method can be used, but a coating method such as a wire bar, a gravure, a micro gravure roll, a reverse roll coater, a slit die, a slide hopper, and a Hirano lip is preferably used. . In the present invention, a micro gravure roll and a slit die are preferable in that the uniformity of the coating film thickness is high and control of the film thickness is easy, and a slit die is particularly preferable in that the coating environment can be made constant.

  The coating liquid containing a liquid crystalline compound according to the present invention will be described.

  In order to apply the liquid crystal compound, the temperature (the temperature of the coating solution, the temperature at the time of application, etc.) is an important factor. When the temperature of the coating solution is low, a liquid crystal compound in the coating solution is liable to cause a coating failure due to crystallization or agglomeration, and the same phenomenon occurs on the support immediately after coating. The problem was easy to happen.

  Conversely, when the temperature of the coating solution is high, the solvent in the coating solution is likely to evaporate, causing coating failure due to the concentration control of the coating solution, the generation of aggregates due to evaporation of the solvent, and the intake of water vapor from the outside. I found it easy.

  Therefore, in order to preferably obtain the effects described in the present invention, the application temperature of the liquid crystal compound is 15 ° C. to 30 ° C., the application temperature is 15 ° C. to 30 ° C., and the application environment temperature is 20 ° C. to 30 ° C. It is preferable to adjust.

  Moreover, it is preferable that the place where the coater is installed is also adjusted to the range of the coating environment temperature.

  Here, the coating temperature represents the coater temperature, the temperature of the support, and the roll temperature for holding the support at the time of coating. The coating environment temperature is 5 cm from the top of the support immediately before entering the drying zone immediately after coating. The temperature in the region up to the height. Further preferable coating solution temperature, coating temperature, and coating environment temperature are each 20 ° C. or more and 28 ° C. or less, and each temperature difference is within ± 5 ° C. From the viewpoint of

  A solvent (also referred to as a solvent) used for preparing a coating solution containing the liquid crystalline compound described above will be described. The solvent to be used may be used alone, or two or more solvents may be mixed and used in order to control the drying property at the time of coating. The solvent of the solution for coating is preferably an organic solvent. Examples of alcohols include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol, pentanol, 2-methyl-2-butanol, cyclohexanol, and the like. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone. Examples of esters include methyl formate, ethyl formate, methyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, ethyl lactate, and lactic acid. Examples of glycol ethers (C1 to C4) include methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene. As glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether, or propylene glycol mono (C1-C4) alkyl ether esters, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, other Examples of the solvent include methylene chloride and N-methylpyrrolidone. In particular, it is not limited to these.

  In the production method of the present invention, it is important to control the wind speed on the surface of the liquid crystal layer in the drying step after coating the liquid crystal layer. This will be described below.

  Usually, a method is adopted in which a wind at a constant temperature is circulated in a drying apparatus to dry a material coated on a long support. However, it has been found that this wind affects the uniformity of the liquid crystal layer, and the liquid crystal layer is deformed and uneven by the wind. Therefore, it is preferable that wind is not applied to the liquid crystal layer after coating as much as possible. The wind speed of the wind hitting the liquid crystal layer is preferably 4 m / sec or less, more preferably 3 m / sec or less, and particularly preferably from 0.3 m / sec to 2 m / sec.

  It was also found that when there was a large amount of residual solvent at the beginning of drying, it was more susceptible to wind. When the residual solvent and the wind speed hitting the film surface are examined in detail, the wind speed hitting the film surface is preferably 1 m / sec or less, more preferably 0.9 m / sec or less until the residual solvent of the liquid crystal layer is 5% or less. Especially preferably, it is 0.1 m / sec to 0.7 m / sec. Examples of a method for adjusting the wind hitting the liquid crystal layer include a method by adjusting an exhaust valve of a drying measure, and a method of adjusting the shape of the air outlet in the drying device (FIGS. 1 and 2). The wind speed can be measured using a commercially available anemometer, for example, an anemometer MODEL6112 (manufactured by Nippon Kanomax Co., Ltd.).

  In the present invention, the alignment treatment is preferably performed after the liquid crystal compound is applied. The alignment treatment is a step of promoting (ripening) the alignment of the liquid crystalline compound by holding the liquid crystalline compound in a specific temperature range for a specific time. Although this step may be performed after drying, it is preferable in terms of productivity to be performed simultaneously with the drying step. If the alignment treatment is not sufficient, a portion in which the liquid crystal compound is not finely aligned (hereinafter referred to as disclination) occurs, the alignment is disturbed, the contrast is lowered, and the tilt angle is lower than the design value. Occurred. As a result of examining the temperature of the alignment treatment, after applying the liquid crystalline compound, the liquid crystalline compound is equal to or higher than the temperature at which the liquid crystalline compound changes from the isotropic phase to the nematic phase (hereinafter referred to as T-IN) and from the nematic phase to the isotropic phase. It was found that in the temperature range below (hereinafter referred to as T-NI), the orientation of the liquid crystal compound is disturbed, disclination is likely to occur, and the tilt angle is lowered. It can be estimated that this is an unstable temperature region of the liquid crystal compound.

The liquid crystal material according to the present invention (also referred to as a liquid crystal compound or liquid crystal) exhibits a nematic phase and shows a relationship of T-NI ≧ I-IN. The measuring method of T-NI and T-IN can be measured by DSC method. Specifically, the measurement was performed using a DSC821 ^E manufactured by Mettler Co., Ltd. The measurement of T-NI and T-IN is described in “Chemical Review, Chemistry of Liquid Crystals (Edited by Chemical Society of Japan)” and the like, but can be performed using a differential scanning calorimeter (DSC). T-NI is the temperature from the nematic phase to the isotropic phase at the time of temperature rise, and is the peak of the transition point from the nematic phase to the isotropic phase in the obtained graph.

T-IN is the temperature from the isotropic phase to the nematic phase when the temperature is lowered, and is the peak of the transition point from the isotropic phase to the nematic phase in the obtained graph. The measuring device uses DSC821 ^E manufactured by METTLER Co., Ltd., and the same sample is measured three times at a rate of 5 ° C./min. The measurement results after the second time were averaged.

  Furthermore, when it examined in detail, it discovered that disclination would reduce remarkably if it hold | maintains more than T-NI after apply | coating a liquid crystalline compound. Further, it has been found that if the temperature is held at T-NI or higher and then held at T-IN or lower, the time for disclination to disappear is shortened, the tilt angle is increased, and the productivity is improved. Furthermore, it is maintained for 1 second or more and 10 seconds or less above T-NI, for 10 seconds or more below T-IN, or after holding at T-NI or higher and at a temperature range below T-IN and 10 ° C lower than T-IN. It is particularly preferable in terms of orientation, disappearance rate of disclination, tilt angle, and productivity.

  As another preferable orientation condition, it was found that holding at T-IN or less unexpectedly reduces disclination. It is important not to raise the temperature more than T-IN. Especially when a polymerizable liquid crystal is used, a polymerization reaction due to heat can be suppressed, so that a sample with good alignment uniformity and less disclination can be obtained.

  The temperature control of the liquid crystal layer can be controlled by adjusting the temperature of the drying zone and the orientation zone. However, since the thermal conductivity of the support and the alignment layer applied on the support and the liquid crystal layer is low, the temperature of the liquid crystal layer does not rise to a predetermined temperature, and it is applied in a dry zone or alignment zone of a limited length. I couldn't increase the speed. In order to increase the temperature of the liquid crystal layer efficiently, it is effective for improving productivity to contact the support with a metal belt (FIG. 3) or a metal plate (FIG. 4) in a drying zone (also referred to as a heat treatment zone). I understood.

  When a solution containing a liquid crystal compound is applied, the solvent can be dried and removed after application to obtain a liquid crystal layer having a uniform film thickness. The liquid crystal layer can fix the orientation of the liquid crystal compound by the action of heat or light energy, or by a chemical reaction using heat and light energy in combination. In particular, monomeric liquid crystalline compounds that are not polymeric liquid crystalline compounds generally have a low viscosity, and the orientation of the liquid crystalline compound is likely to change due to external causes of heat, so a polymerizable liquid crystalline compound is used by using a photopolymerizable initiator. Can be immobilized by carrying out a curing reaction by a photoradical reaction or the like.

  In the present invention, when fixing the orientation of the liquid crystalline compound, when using an ethylenically unsaturated group as a polymerizable group, when using a photopolymerization initiator, curing during production can be achieved by increasing the activity of the reaction. It is excellent because time can be shortened. For the generation of radicals, the light source described below can be used. For example, a high-pressure mercury lamp or a metal halide lamp that can strongly absorb near ultraviolet rays is preferable, and a maximum value of molar extinction coefficient with respect to light of 360 nm to 450 nm is preferably 100 or more, and more preferably 500 or more. As the light ray as the active ray for photopolymerization, an electron beam, an ultraviolet ray, a visible ray and an infrared ray (heat ray) can be used as necessary, but in general, an ultraviolet ray is preferable. Low-pressure mercury lamps (sterilization lamps, fluorescent chemical lamps, black lights), high-pressure discharge lamps (high-pressure mercury lamps, metal halide lamps), and short arc discharge lamps (ultra-high-pressure mercury lamps, xenon lamps, mercury xenon lamps) Can be mentioned.

  On the other hand, it was found that the alignment was disturbed because the temperature of the liquid crystal layer was increased by ultraviolet irradiation. This is because heat is generated by the energy rays on the long wave side of the active rays, and the orientation tends to be disturbed because it is likely to change from a nematic phase to an isotropic phase. It is therefore important not to exceed the temperature from the nematic phase to the isotropic phase (T-NI) during curing. Specific methods for not raising the liquid crystal layer above the T-NI temperature include the installation of a heat ray cut filter in the UV irradiation device, the use of a water-cooled UV lamp, the use of a reflective plate that transmits infrared rays, and the UV irradiation device (lamp part). And a method of introducing a cooled gas into the ultraviolet irradiation device.

  Radical polymerization initiators for the polymerization reaction of ethylenically unsaturated groups include, for example, azobis compounds, peroxides, hydroperoxides, redox catalysts, such as potassium persulfate, ammonium persulfate, tert-butyl peroctoate, benzoyl peroxide , Isopropyl percarbonate, 2,4-dichlorobenzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, dicumyl peroxide, azobisisobutyronitrile, 2,2'-azobis (2-amidinopropane) hydrochloride Alternatively, benzophenones, acetophenones, benzoins, thioxanthones, and the like can be given. Details thereof are described in “Ultraviolet Curing System” General Technical Center, pages 63 to 147, 1989, and the like.

For polymerization of a compound having an epoxy group, an allyldiazonium salt (hexafluorophosphate, tetrafluoroborate), a diallyl iodonium salt, a group 5 allylonium salt (PF ₆ , AsF ₆ , An allylsulfonium salt having an anion such as SbF ₆ is generally used.

  In addition, when performing a curing reaction using a radical reaction, irradiation with the active ray in a nitrogen atmosphere in order to avoid a delay in the polymerization reaction due to the presence of oxygen in the air reduces the reaction time and reduces the amount of light. It is preferable in terms of curing, and when the film thickness of the liquid crystal layer is 1.5 μm or less, it is particularly preferable that the oxygen concentration is 2% or less. Nitrogen gas is preferably introduced as a method for lowering the oxygen concentration, and in order to lower the oxygen concentration efficiently, a mechanism in which a front chamber is provided in front of the ultraviolet curing device to fill the nitrogen gas is particularly preferred.

  Furthermore, removing the surface air layer with a roll and a blade in the front chamber can reduce the oxygen concentration at a high rate. If the curing is insufficient, blocking occurs when winding, resulting in a coating failure and a problem.

  In order to cure the liquid crystal compound by utilizing these radical reactions, it is important to select a monomeric liquid crystal compound that is not a polymer liquid crystal compound having a reactive group introduced in the liquid crystal compound. is there. The orientation of the liquid crystal compound can be fixed by this curing reaction.

  On the other hand, when the liquid crystalline compound is a polymer liquid crystal, it is not necessary to carry out the curing reaction by the above chemical reaction to fix the alignment of the liquid crystalline compound. This is because the polymer liquid crystalline compound has a glass transition temperature at a temperature range in which the transparent resin substrate does not change due to heat, for example, 90 ° C. or more, and the liquid crystal transition temperature is applied. After installation, the liquid crystal compound is maintained in the liquid crystal transition temperature range and aligned, and then the liquid crystal compound is maintained in alignment by being allowed to cool at a temperature lower than the glass transition temperature, for example, room temperature.

  In addition, when the glass transition temperature of the polymer liquid crystal is higher than the heat resistance temperature of the support, the alignment film is placed on the heat resistant support and the polymer liquid crystal is applied, and then the glass transition temperature of the polymer liquid crystal or higher. Can be held and oriented. This is allowed to cool to room temperature to fix the orientation of the polymer liquid crystal, and then transferred to the support of the present invention using an adhesive to produce an optical compensation film.

  The surface potential during coating of the long support according to the present invention will be described.

  We have found that the charge (surface potential) of the support affects the alignment ability of the alignment layer when a liquid crystalline compound is applied after the alignment layer is applied on the support. This is particularly serious when the coating speed is high, and when the charge amount of the long support is large, the liquid crystalline compound has an influence over the alignment force of the alignment layer. There arises a problem of becoming aligned in the alignment direction.

  From the above, it is preferable to adjust the surface potential of the long support to −5 to +5 kV when the coating liquid containing the liquid crystalline compound is applied on the long support, and further, the long support coated with the alignment layer. From the viewpoint of maintaining the alignment ability of the alignment layer of the support sample, it is preferable to adjust the surface potential of the alignment layer to −5 to +5 kV, more preferably the surface potential of the support on which the alignment layer or the liquid crystalline compound is applied. Is adjusted to −1 to +1 kV. Here, the surface potential of the alignment layer or the long support at the time of application was measured immediately after being unwound from the original roll and immediately before applying the liquid crystalline compound with a coater, that is, within 0 to 3 m before the coater. Indicates a value. In particular, the effect is remarkable by setting the surface potential within the above range immediately before the support is conveyed from the former roll and immediately before the coater.

  The surface potential described above can be measured with a commercially available surface potential meter.

  The method for measuring the surface potential of the long support according to the present invention is not particularly limited and can be carried out by a conventionally known method. For example, a method of selecting the material of the other party in contact with the support during roll conveyance from the charged column and selecting the charged column in a position where the charge amount is small relative to the support of the support, A method of reducing the contact area with the support by moderately roughening, and a method of reducing the contact area with the roll by incorporating a matting agent in the support or coating a composition containing the matting agent on the surface , A method of improving the conductivity of the support by containing or applying a conductive substance in or on the support, a method of increasing the relative humidity of the external atmosphere to reduce the surface leakage resistance of the support, and ionizing the gas Ion is sprayed onto the support to neutralize the charge on the support surface, the surface potential of the support is reduced using a static eliminator, or the tip is discharged by a grounded needle-like or linear metal. Leakage of charge on support surface Method and the like can be mentioned to. These methods may be used in combination.

  The static electricity removing device for the support may be any device that can remove or reduce the static electricity on the support, and examples thereof include a static elimination bar, a static elimination yarn, or an ion blowing static electricity elimination device. Among these, an ion blowing type static eliminator is preferable. The ion blow type static eliminator is an apparatus having a structure in which a gas is ionized by corona discharge, flame plasma, ultraviolet rays, a heated metal body, a radioisotope, and the like to generate ions, and the generated ions are sprayed on an object. The static eliminator using corona discharge is composed of an electrode unit with a built-in high-voltage transformer, a blowing unit, a gas supply unit, a controller, and the like. The electrode unit generates corona discharge, ionizes the gas, and the blowing unit Ionized gas is sprayed onto the object. Usually, air is used as the gas to be supplied. However, by introducing an inert gas and setting the oxygen concentration in the gas to 10% by volume or less, it is possible to improve the safety against dangerous substances. preferable. The type of the inert gas is not particularly limited, but may be a gas such as nitrogen, carbon dioxide, or argon. Nitrogen and carbon dioxide are preferable from the viewpoint of cost. It can be implemented by providing a flow meter in the gas supply unit and supplying these gases.

In the present invention, it is also a preferable method that the ground leakage resistance of the roll of the coating apparatus is 10 ⁶ Ω or less. It is preferable to connect the casting support and the roll as well as the casting support and the roll and the ground. By increasing the capacity with respect to the ground and reducing the resistance, the surface potential of the support can be adjusted to be low, and an alignment layer that aligns the liquid crystalline compound well and a liquid crystal layer that is excellent in alignment can be formed.

  The place where the static eliminator is installed is preferably from 0 to 3 m before the coating coater from the roll-out film roll-out part, and the distance between the static eliminator and the support is preferably 10 to 100 mm. The static eliminator can be installed on any surface of the support.

  It is intended to improve the sticky deformation seen when the rolled roll film is unwound from the roll. Static electricity is generated between the exit of the dryer and the winder, particularly immediately before winding. This is done by installing a removal device. As the static eliminator, the above can be used without limitation, but a simple one such as a static elimination bar or static elimination yarn is preferable. The neutralization bar is not particularly limited, but a corona discharge type is preferably used, for example, SJ-B01 manufactured by Keyence Corporation. The static elimination yarn is not particularly limited, but usually a flexible yarn is preferably used. For example, Naslon 12/300 × 3 is used. The distance between the static eliminator and the support is preferably 10 to 100 mm, and the static eliminator can be installed on any surface of the support.

  In order to reduce the charge amount of the support, a method of adding a conductive material to the support and a method of applying a conductive material are preferable. As the conductive material that is preferably used, an ionic polymer compound, a metal oxide, or the like is preferably used.

  Examples of the ionic polymer compound include anionic polymer compounds such as those described in JP-B-49-23828, JP-A-49-23827, and JP-A-47-28937; JP-B-55-734, JP-A-50-54672 Ionene type polymers having a dissociating group in the main chain, as seen in JP-B Nos. 59-14735, 57-18175, 57-18176, 57-56059, etc .; No. 57-15376, No. 53-45231, No. 55-145783, No. 55-65950, No. 55-67746, No. 57-11342, No. 57-19735, No. 58-56858. No., JP-A 61-27853, 62-9346, and a cationic pendant type having a cationic dissociation group in the side chain Rimmer; and the like.

  Furthermore, in order to apply the liquid crystalline compound, the drying speed and the conveying method are important in terms of applicability. For example, when the liquid crystal compound is applied under a condition where the drying speed is low, a problem of spotted unevenness is likely to occur in the liquid crystal layer. When this phenomenon was analyzed in detail, when a coating liquid containing a liquid crystalline compound was applied on the alignment layer on the long support, it was caused by temperature unevenness when the solvent in the liquid crystalline compound coating liquid evaporated. I was able to guess.

  Therefore, it is sufficient to reduce the temperature unevenness in order to solve the problem of spotted unevenness. Methods for reducing the temperature unevenness include a method of reducing the solvent of the coating solution containing the liquid crystalline compound, and a thin coating film thickness. A method for controlling the evaporation rate by selecting a solvent, a method for reducing the influence of temperature from the transport roll, and the like.

  Above all, it is particularly effective in adjusting to minimize the influence of the temperature from the transport roll. After coating the liquid crystal layer on the long support, the residual solvent amount of the liquid crystal layer is 10% or less. It is preferable to dry in a non-contact manner until it becomes, and it is particularly preferable to dry in a non-contact manner until the remaining coating solution is 5% or less. Examples of the non-contact conveyance method include a method in which the roll interval is increased, a method in which the support is floated with a gas such as air or nitrogen gas, a method in which the support is sandwiched between clips, and the like.

  The optically anisotropic layer of the optical compensation film of the present invention improves the viewing angle characteristics of the liquid crystal display. Therefore, the thickness of the optically anisotropic layer depends on the birefringence of the liquid crystalline compound constituting the optical anisotropic layer and the liquid crystalline compound. Although it varies depending on the orientation state, the film thickness is 0.2 μm or more and 5 μm or less, preferably 0.4 μm or more and 3 μm or less. If the optical anisotropic layer is thinner than this, it is difficult to obtain the desired optical anisotropy. On the other hand, if the optical anisotropic layer is thicker than the aforementioned range, the optical anisotropy is more than necessary and the viewing angle is changed. In many cases, the optical compensation film tends to curl easily, as another characteristic.

  At least one optically anisotropic layer according to the present invention can be provided on the transparent support. An optical compensation film capable of optically compensating for various liquid crystal display modes can be designed with optical characteristics suitable for the display. A plurality of optical anisotropic layers can be provided on one transparent support, and the liquid crystalline compound contained in the optical anisotropic layer is oriented or the orientation of the liquid crystalline compound is fixed. The orientation direction can be designed with optical characteristics suitable for the display. When two or more optically anisotropic layers are provided on the transparent support, a plurality of orientation layers and optically anisotropic layers can be provided repeatedly in the order of the distance from the transparent support. This is because the alignment direction is determined by the alignment film, and the alignment film and the liquid crystal layer must be adjacent to each other. When these layers are installed in multiple layers, an alignment layer is directly coated on the liquid crystal layer coated on the alignment layer, or an intermediate layer composed of other conventionally known resin layers is placed on the alignment layer. A liquid crystal layer can be provided on the plurality of alignment layers by coating a film.

  It is preferable to provide means for confirming the applicability of the optically anisotropic layer according to the present invention. However, since the aligned liquid crystal layer is transparent, it is difficult to check for unevenness. Therefore, after the liquid crystal layer is applied, the two polarizing plates are placed in a crossed Nicols arrangement, and the liquid crystal layer is placed between the transmission axis of the polarizing plate and the orientation direction of the liquid crystal at 45 ° and / or parallel to the transmission axis of one polarizing plate. A method of measuring the amount of transmitted light by irradiating transmitted light from one side through the measured direction and detecting the unevenness of the liquid crystal layer with the transmitted light amount is preferable. For example, it is possible to detect an abnormal portion of the density by expressing the transmitted light as a density, or to manage the process by the density deviation.

  When the optical compensation film of the present invention is installed in a liquid crystal display device, an upper polarizing plate and a lower polarizing plate arranged above and below a pair of substrates located on both sides of the driving liquid crystal cell are usually configured. At least one optical compensation film of the present invention is installed between the substrate and either the upper or lower polarizing plate, or between the substrate and the upper and lower polarizing plates.

  When the liquid crystal display device is a twisted nematic type (TN type) liquid crystal display device in particular, an optical compensation film is attached in a direction in which the transparent support surface of the optical compensation film is in contact with the substrate closest to the TN type liquid crystal cell, and optical It is preferable that the maximum refractive index direction in the surface of the transparent support of the compensation film is attached in a direction substantially perpendicular to the alignment direction of the nematic liquid crystal of the substrate closest to the liquid crystal cell, from the viewpoint that the effect of the present invention is more preferable. Here, “substantially orthogonal” indicates a range of 90 ° ± 5 °, preferably 90 °.

  In the optical anisotropic layer according to the present invention, the average inclination angle is preferably oblique when observed from the cross-sectional direction of the optical anisotropic layer, and the inclination angle is constant with respect to the thickness direction of the optical anisotropic layer. The orientation angle may change with respect to the thickness direction. The average tilt angle varies depending on the display design in order to compensate for the viewing angle of the display, but is preferably 15 ° or more and 50 ° or less, particularly in a TN liquid crystal display device. More preferably, the tilt angle of the liquid crystal compound constituting the optically anisotropic layer changes with respect to the thickness direction, and the tilt angle changes by increasing or decreasing from the alignment film side. Is.

  The long support according to the present invention will be described.

  The elongate support according to the present invention specifically indicates those having a length of 5 m or more, and is usually in the form of a roll.

  Further, the long support used in the optical compensation film of the present invention is preferably a transparent support, and the transparent support preferably has a property that the transmittance in the visible region is 80% or more. Examples of the material include cellulose ester derivatives, polyethylene terephthalate, polycarbonate, polyarylate, and polysulfone. Among the above descriptions, cellulose ester derivatives are preferably used from the viewpoint of productivity for obtaining desired optical characteristics.

The optical characteristics of the transparent support used for the long support according to the present invention are such that the optical characteristics of the support satisfy 40 nm ≦ R ₀ ≦ 95 nm and 0.8 ≦ (R _t / R ₀ ) ≦ 1. 4 is required. Here, R ₀ and R _t represent retardation values of the transparent support.

R ₀ = (nx−ny) × d
R _t = ((nx + ny) / 2−nz) × d
Here, nx and ny are the maximum refractive index direction in the plane of the transparent support = the main refractive index in the x direction and the y direction. nz is the refractive index of the film in the thickness direction, and d is the thickness (nm) of the film.

  From the viewpoint of productivity of the transparent support, a preferable production method is to cast a resin solution containing the solvent of the transparent support on a belt or drum, peel the film from the belt or drum with the solvent remaining, and then dry it. It is a manufacturing method which extends | stretches a film, carrying out. Therefore, the transparent support can be more efficiently produced when the main refractive index of the transparent support shows the following relationship. nx is a refractive index substantially equal to the casting direction of the film, ny is a refractive index substantially equal to a direction perpendicular to the casting direction (width direction), and nz is a refractive index in the thickness direction of the film.

An ordinary refractometer can be used to measure the refractive index of the entire support. After measuring the total refractive index, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), measuring the three-dimensional refractive index in an environment of 23 ° C. and 55% RH at a wavelength of 590 nm The retardations R ₀ and R _t can be obtained by calculating the refractive indexes nx, ny and nz and measuring the thickness of the film.

A cellulose ester derivative is preferably used as the resin that satisfies such characteristics. In particular, in order to effectively satisfy 0.5 ≦ (R _t / R ₀ ) ≦ 2.0, the degree of acetyl substitution of the cellulose ester is preferably 2.5 or more and 2.86 or less. As another embodiment of the present invention, at least two cellulose esters having a cellulose ester having an acetyl substitution degree of 2.40 or more and 3.00 or less are used. In this case, the substitution degree of the acetyl group is preferably a cellulose ester having an average substitution degree of acetyl group after mixing of 2.50 or more and 2.86 or less from the viewpoint that the effects of the present invention are preferably achieved.

  In still another embodiment of the present invention, the cellulose ester used in the optical compensation film has at least one cellulose ester having a degree of acetyl substitution of 2.60 or more and 3.00 or less and a degree of acetyl substitution of 2.40 or more and 2. It is preferable that at least one cellulose ester of less than 60 is mixed, and a cellulose ester having an average degree of acetyl substitution after mixing of 2.5 or more and 2.86 or less is used from the viewpoint of preferably exhibiting the effects of the present invention.

  A support made of a cellulose ester having a degree of acetyl substitution or an average degree of acetyl substitution of 2.5 or more and 2.86 or less is a film having optical characteristics having a high difference between the refractive index in the thickness direction and the average refractive index of the film surface. give. By using cellulose ester films with a degree of substitution kept somewhat low, if these cellulose ester films are used, the film can be made thinner if the same optical properties are obtained as compared with a cellulose triacetate film having a high degree of acetyl substitution. The support of the optical compensation film having excellent viewing angle characteristics can be designed by appropriately adjusting the optical characteristics of the liquid crystal layer and the support, although the required optical compensation ability of the display is different. The preferred range of the degree of acetyl substitution or the average degree of acetyl substitution of the support of the present invention is 2.55 to 2.70.

  The cellulose ester film described above can be synthesized, for example, by the method described in JP-A-10-45804. The measuring method of the substitution degree of an acetyl group can also be measured by ASTM-D817-96.

  The cellulose ester having an acetyl group substitution degree of 2.5 or more and 2.86 or less is an acetyl group in which a hydroxyl group of cellulose is substituted with a predetermined substitution degree by a conventional method. The number average molecular weight of the cellulose ester according to the present invention is preferably from 70,000 to 300,000, more preferably from 80,000 to 200,000, in order to obtain a preferable mechanical strength.

  The cellulose ester having an acetyl group substitution degree of 2.60 or more and 3.00 or less is an acetyl group in which a hydroxyl group of cellulose is substituted with a predetermined substitution degree by a conventional method. The number average molecular weight of the cellulose ester of the present invention is preferably from 70,000 to 300,000, more preferably from 80,000 to 200,000, in order to obtain a preferable mechanical strength.

  A cellulose ester having an acetyl substitution degree of 2.40 or more and less than 2.60 is a cellulose ester having a hydroxyl group substituted with a predetermined substitution degree by an ordinary method. The number average molecular weight of the cellulose ester is preferably from 70,000 to 300,000, more preferably from 80,000 to 200,000, in order to obtain a preferable mechanical strength.

  As the cellulose ester resin, it is preferable to use a cellulose ester resin having a controlled degree of acetyl substitution. On the other hand, it is very effective to use a cellulose ester resin having an acetyl group and a propionyl group.

  As an example of the cellulose ester used for producing the cellulose ester film according to the present invention, those having an acetyl group and a propionyl group as substituents and satisfying the following formulas (1) and (2) at the same time are preferable.

(1) 2.0 ≦ A + B ≦ 3.0
(2) A <2.4
Here, A represents the degree of substitution of the acetyl group, and B represents the degree of substitution of the propionyl group.

  Furthermore, in this invention, the cellulose-ester film which satisfy | fills following formula (3) and (4) simultaneously is used more preferable.

(3) 2.4 ≦ A + B ≦ 2.8
(4) 1.4 ≦ A ≦ 2.0
These acyl groups may be substituted on the 2nd, 3rd and 6th positions of the glucose unit on average, and may be substituted with a distribution such as substitution at a high ratio at the 6th position, for example. good.

  Here, the degree of substitution refers to a so-called percentage of the amount of bound fatty acid, and is a numerical value calculated according to the measurement and calculation of the degree of acetylation in ASTM-D817-91 (test method for cellulose acetate and the like). The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  In particular, it is particularly preferable that the average degree of substitution of the acetyl group of A is less than 2.0 because there is little variation in retardation during stretching.

  Further, from the viewpoint of obtaining a transparent support excellent in mechanical strength, the number average molecular weight of the cellulose ester resin containing both the acetyl group and the propionyl group used in the present invention is 70000-300000, preferably 90000-200000.

  The mixed fatty acid ester of cellulose used in the present invention can be synthesized using an acid anhydride or acid chloride as an acylating agent. When the acylating agent is an acid anhydride, an organic acid (eg, acetic acid) or methylene chloride is used as a reaction solvent. As the catalyst, an acidic catalyst such as sulfuric acid is used. When the acylating agent is an acid chloride, a basic compound is used as a catalyst. In the industrially most common synthesis method, cellulose is mixed with an organic acid component containing an organic acid (acetic acid, propionic acid) corresponding to acetyl group and propionyl group or an acid anhydride thereof (acetic anhydride, propionic anhydride). The cellulose ester is synthesized by esterification. The amount of the acetylating agent and propionylating agent used is adjusted so that the ester to be synthesized falls within the range of the substitution degree described above. The amount of the reaction solvent used is preferably 100 to 1000 parts by mass, and more preferably 200 to 600 parts by mass with respect to 100 parts by mass of cellulose. It is preferable that the sample amount of an acidic catalyst is 0.1-20 mass parts with respect to 100 mass parts of cellulose, More preferably, it is 0.4-10 mass parts.

  The reaction temperature is preferably 10 to 120 ° C, more preferably 20 to 80 ° C. Further, after completion of the acylation reaction, the degree of substitution may be adjusted by hydrolysis (saponification) as necessary. After completion of the reaction, the reaction mixture is separated using conventional means such as precipitation, washed and dried to obtain a mixed fatty acid ester of cellulose (cellulose acetate propionate).

  As the cellulose ester used in the present invention, either cellulose triacetate synthesized from cotton linter or cellulose triacetate synthesized from wood pulp can be used alone or in combination. It is preferable to use a large amount of cellulose ester synthesized from a cotton linter that has good releasability from a belt or drum because of high production efficiency. When the ratio of cellulose ester synthesized from cotton linter is 60% by mass or more and the effect of peelability becomes remarkable, 60% by mass or more is preferable, more preferably 85% by mass or more, and most preferably used alone. preferable.

  As the cellulose ester, either a cellulose ester synthesized from cotton linter or a cellulose ester synthesized from wood pulp can be used alone or in combination. It is preferable to use a large amount of cellulose ester synthesized from a cotton linter that has good releasability from a belt or a drum because of high productivity efficiency. The ratio of cellulose ester synthesized from cotton linter is 60% by mass or more, and since the effect of peelability becomes remarkable, 60% by mass or more is preferable, more preferably 85% by mass or more, and further, it can be used alone. Most preferred.

  The thickness of the transparent support used in the optical compensation film of the present invention may be controlled by the stretching ratio and the thickness of the transparent support, as long as it has optical characteristics for improving the viewing angle characteristics of the liquid crystal display. . The thickness of the transparent support is preferably from 35 μm to 250 μm, more preferably from 60 μm to 140 μm. If the transparent support is thinner than this range, it becomes difficult to obtain the desired optical characteristics. On the other hand, if the transparent support is thicker than this range, the optical characteristics become more than necessary, and the viewing angle characteristics of the liquid crystal display are often deteriorated.

  In the present invention, when the optical compensation film is used as a protective film for a polarizing plate, or when the optical compensation film is attached to a polarizer with a protective film, the optical compensation film is installed between the liquid crystal cell and the polarizer. Can do.

  A conventionally well-known thing can be used for a polarizer. For example, a film made of a hydrophilic polymer such as polyvinyl alcohol, which has been stretched by treatment with a dichroic dye such as iodine can be used.

  Next, when the transparent support of the present invention is a cellulose ester, a method for producing the film will be described.

  First, a cellulose ester is dissolved in an organic solvent to form a dope. The concentration of the cellulose ester in the dope is preferably 10 to 35% by mass.

  Examples of the organic solvent include methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3 , 3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3 , 3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, non-chlorine organic solvents such as nitroethane can be used. Also, methylene chloride can be used. Use of a lower alcohol such as methanol, ethanol, or butanol is preferred because the solubility of the cellulose ester in an organic solvent can be improved and the dope viscosity can be reduced. In particular, ethanol having a low boiling point and low toxicity is preferred.

  You may add additives, such as the said plasticizer, a ultraviolet absorber, and a mat agent, in dope. The obtained dope is cast on a rotating belt or drum support, dried until it can be peeled, and the film is peeled off. The film can be stretched in the state of a peeled and dried film, and further dried to evaporate the organic solvent in the film almost completely. However, the film may be stretched after drying. The content of the organic solvent in the film is preferably 2% by mass or less, and more preferably 0.4% by mass or less in order to obtain good dimensional stability of the film.

  Further, in the production of the long support according to the present invention, particularly in coating, in order to improve the slipperiness, during the dope when producing these transparent resin films, for example, silicon dioxide, titanium dioxide, aluminum oxide, oxidation It is preferable to contain matting agents such as inorganic fine particles such as zirconium, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate, and a crosslinked polymer. Of these, silicon dioxide is preferable because it can reduce the haze of the film. The fine particles preferably have an average secondary particle size of 0.01 to 1.0 μm and a content of 0.005 to 0.3% by mass with respect to the cellulose ester.

  It is preferable that fine particles such as silicon dioxide are surface-treated with an organic substance because the haze of the film can be reduced. Preferred organic materials for the surface treatment include halosilanes, alkoxysilanes, silazanes, siloxanes, and the like. The average diameter of the fine particles is the same as the fine particles used for the anti-curl treatment described later.

  The optical compensation film of the present invention often curls because it has a coating such as an optically anisotropic layer on the support. Therefore, by preventing curling, the anti-curl layer can be provided on the opposite side to which the optically anisotropic layer is applied in order to eliminate the inconvenience caused by curling and not to impair the function as an optical compensation film. In other words, the degree of curling is balanced by imparting the property of curling with the surface provided with the anti-curl layer inside. The anti-curl layer is preferably applied also as a blocking layer. In this case, the coating composition can contain inorganic fine particles and / or organic fine particles for imparting an anti-blocking function. Examples of the inorganic fine particles include silicon oxide, titanium oxide, aluminum oxide, tin oxide, zinc oxide, calcium carbonate, barium sulfate, talc, kaolin, calcium sulfate, and the like, and examples of the organic fine particles include polymethacrylic acid. Methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder Polyamide-based resin powder, polyimide-based resin powder, or polyfluorinated ethylene-based resin powder, and the like, which can be added to the anti-curl layer coating composition. It is preferable that fine particles such as silicon dioxide are surface-treated with an organic substance because the haze of the film can be reduced. Preferred organic materials for the surface treatment include halosilanes, alkoxysilanes, silazanes, siloxanes, and the like.

  Examples of the silicon dioxide fine particles include AEROSIL200, 200V, 300, R972, R974, R202, R812, OX50, TT600, etc. manufactured by Nippon Aerosil Co., Ltd., preferably AEROSIL R972, R972V, R974, R974V, R202, R812, etc. Is mentioned.

  These particles are preferably added in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the resin composition. These fine particles are preferably blended so that the haze of the film is 0.6% or less and the dynamic friction coefficient between the front and back surfaces of the optical compensation film is 0.5 or less.

  The fine particles may be provided with a layer containing a resin such as diacetylcellulose. Such a layer can also be improved in strength using a crosslinking agent such as an isocyanate derivative.

  The application of the anti-curl function is performed by applying a composition containing a solvent that dissolves or swells the resin film substrate. As a solvent to be used, in addition to a solvent to be dissolved or a mixture of solvents to be swollen, there may be a solvent that is not dissolved, and a composition in which these are mixed at an appropriate ratio depending on the degree of curl of the resin film and the type of resin and the coating amount. To do. In order to enhance the curl prevention function, it is effective to increase the mixing ratio of the solvent that dissolves the solvent composition to be used or the solvent that swells and to decrease the ratio of the solvent that does not dissolve.

  This mixing ratio is preferably (solvent to be dissolved or solvent to be swollen) :( solvent not to be dissolved) = 10: 0 to 1: 9.

  Examples of the solvent for dissolving or swelling the resin film substrate contained in such a mixed composition include benzene, toluene, xylene, dioxane, acetone, methyl ethyl ketone, N, N-dimethylformamide, methyl acetate, ethyl acetate, Examples include trichloroethylene, methylene chloride, ethylene chloride, tetrachloroethane, trichloroethane, and chloroform. Examples of the solvent that does not dissolve include methanol, ethanol, n-propyl alcohol, i-propyl alcohol, and n-butanol.

  These coating compositions are preferably applied to the surface of the resin film using a gravure coater, dip coater, reverse coater, extrusion coater or the like, with a wet film thickness of 1 to 100 μm, particularly preferably 5 to 30 μm. Examples of the resin used here include vinyl chloride / vinyl acetate copolymer, vinyl chloride resin, vinyl acetate resin, copolymer of vinyl acetate and vinyl alcohol, partially hydrolyzed vinyl chloride / vinyl acetate copolymer, and chloride. Vinyl-based vinyl chlorides such as vinyl / vinylidene chloride copolymer, vinyl chloride / acrylonitrile copolymer, ethylene / vinyl alcohol copolymer, chlorinated polyvinyl chloride, ethylene / vinyl chloride copolymer, ethylene / vinyl acetate copolymer Polymers or copolymers, cellulose ester resins such as nitrocellulose, cellulose acetate propionate, diacetyl cellulose, cellulose acetate butyrate resin, copolymers of maleic acid and / or acrylic acid, acrylic acid ester copolymers, acrylonitrile / Styrene copolymer, salt Polyethylene, acrylonitrile / chlorinated polyethylene / styrene copolymer, methyl methacrylate / butadiene / styrene copolymer, acrylic resin, polyvinyl acetal resin, polyvinyl butyral resin, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin , Polyether resins, polyamide resins, amino resins, styrene / butadiene resins, rubber resins such as butadiene / acrylonitrile resins, silicone resins, fluorine resins, and the like, but are not limited thereto. Particularly preferred is a cellulose resin layer such as diacetylcellulose.

  A plasticizer can be used for the purpose of improving physical properties in the support of the optical compensation film of the present invention. As a specific plasticizer, phosphoric acid ester or carboxylic acid ester is preferably used. Phosphoric esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP), biphenyl-diphenyl phosphate, dimethyl ethyl phosphate. Representative carboxylic acid esters include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diethyl hexyl phthalate (DEHP), ethyl phthalyl ethyl glycolate and the like. As the citrate ester, acetyl triethyl citrate (OACTE) and acetyl tributyl citrate (OACTB) are used. Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phosphate ester plasticizers (TPP, TCP, biphenyl-diphenyl phosphate, dimethylethyl phosphate) and phthalate ester plasticizers (DMP, DEP, DBP, DOP, DEHP) are preferably used.

  Of these, triphenyl phosphate (TPP) and ethyl phthalyl ethyl glycol are particularly preferably used.

  The plasticizer is preferably added in an amount of usually 2 to 15% by mass in the transparent resin for imparting water resistance to the transparent resin or improving its moisture permeability.

  By including an ultraviolet absorber in the transparent resin, an optical compensation film excellent in light resistance can be obtained. Examples of the ultraviolet absorber useful in the present invention include salicylic acid derivatives, benzophenone derivatives, benzotriazole derivatives, benzoic acid derivatives, and organometallic complex salts. Although not specifically limited as specific examples, for example, salicylic acid derivatives such as phenyl salicylate, 4-t-butylphenyl salicylic acid, etc., and benzophenone derivatives such as 2-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, etc. Benzotriazole derivatives include 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole, 2- (2'-hydroxy-3'-5'-di-butylphenyl) -5-chlorobenzo Triazole and the like, resorcinol-monobenzoate as benzoic acid derivatives, 2 ′, 4′-di-t-butylphenyl-3,5-t-butyl-4-hydroxybenzoate, etc., nickel as organic complex derivatives Bis-octylphenylsulfamide, ethyl-3,5-di Nickel salts of t- butyl-4-hydroxybenzyl phosphoric acid. In this invention, it is preferable to use 1 or more types of these ultraviolet absorbers, and you may contain 2 or more types of different ultraviolet absorbers. Further, a polymeric ultraviolet absorber, for example, those exemplified in JP-A-6-148430 may be used.

  As the ultraviolet absorber, from the viewpoint of the ultraviolet absorption shape and storage stability, the ultraviolet absorber is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystalline compound, and has good liquid crystal display properties. Those having as little absorption of visible light as possible with a wavelength of 400 nm or more are preferably used. In particular, the transmittance at a wavelength of 370 nm needs to be 10% or less, preferably 5% or less, more preferably 2% or less. From such a viewpoint, a benzotriazole derivative or a benzophenone derivative is preferably used.

  The ultraviolet absorber may be added to the dope after dissolving the ultraviolet absorber in an organic solvent such as alcohol, methylene chloride, dioxolane, or directly into the dope composition. For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope.

  The order of coating the anti-curl layer may be before or after coating the optically anisotropic layer on the opposite side of the resin film substrate, but if the anti-curl layer also serves as an anti-blocking layer, coat it first. It is desirable.

  A protective layer may be provided on the liquid crystal layer of the optical compensation film of the present invention in order to avoid optical alteration such as scratches. In the case where the liquid crystal layer has a plurality of layers, an intermediate layer may be provided. Materials for the protective layer or intermediate layer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, poly (N-methylolacrylamide), styrene / vinyltoluene copolymer, Nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, and polycarbonate, or polymers such as acrylate and methacrylate, and their derivatives Can be mentioned. These materials can be installed by preparing a solution, applying and drying by the above application method.

  The manufacturing method of the cellulose ester film support used in the present invention will be described.

  As a method for producing a cellulose ester film support, a dope solution is cast on the support, a film is formed, the resulting film is peeled off from the support, and then dried while transporting through the drying zone under tension. The solution casting film forming method is preferable. The solution casting film forming method will be described below.

  (1) Dissolution step: In this step, the flakes are dissolved in an organic solvent mainly composed of a good solvent for cellulose ester flakes in a dissolution vessel while stirring to form a cellulose ester solution (dope). For dissolution, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, M.M. G. Makromol. chem. 143, page 105 (1971), as described in JP-A-9-95544 and JP-A-9-95557, various dissolution methods such as a cooling dissolution method that dissolves at a low temperature and a method performed at a high pressure. There is a way. After dissolution, the dope is filtered with a filter medium, defoamed, and sent to the next process with a pump.

  (2) Casting step: The dope is fed to a pressure die through a pressurized metering gear pump, and an endless metal belt for infinite transfer or a support for casting a rotating metal drum at the casting position (hereinafter simply referred to as “casting”). This is a step of casting a dope from a pressure die onto a support. The surface of the casting support is a mirror surface. Other casting methods include a doctor blade method in which the film thickness of the cast dope film is adjusted with a blade, or a reverse roll coater method in which the film is adjusted with a reverse rotating roll, but the slit shape of the die part is prepared. A pressure die that is easy to make uniform in film thickness is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. In order to increase the film forming speed, two or more pressure dies may be provided on the casting support, and the dope amount may be divided and stacked.

  (3) Solvent evaporation step: This is a step of evaporating the solvent by holding the web (the dope film is referred to as the web after casting the dope on the casting support). . In order to evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. The drying efficiency is good and preferable. A method of combining them is also preferable.

  (4) Peeling step: This is a step of peeling the web where the solvent has evaporated on the support at the peeling position. The peeled web is sent to the next process. If the residual solvent amount (the following formula) of the web at the time of peeling is too large, peeling will be difficult, or conversely, if it is peeled off after sufficiently drying on the support, part of the web will be peeled off.

  As a method for increasing the film forming speed (the film forming speed can be increased because the film is peeled off while the amount of residual solvent is as large as possible), there is a gel casting method (gel casting) that can be removed even if there is a large amount of residual solvent. However, it can be peeled off as much as possible to increase the film-forming speed). For example, a poor solvent for the cellulose ester is added to the dope, and the dope is cast and then gelled, and the temperature of the support is lowered to gel. There is also a method of adding a metal salt in the dope. By gelling on the support and strengthening the film, it is possible to speed up the peeling and increase the film forming speed. When peeling at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling will be damaged, and slippage and vertical stripes due to peeling tension will tend to occur, and the amount of residual solvent will be reduced in consideration of economic speed and quality. It is decided.

  The amount of residual solvent was determined from the following formula, where A is the mass of the film when the film is dried at 115 ° C. for 1 hour, and B is the mass of the film before drying.

((BA) / A) × 100 = residual solvent amount (% by mass)
(5) Drying step: a step of drying the web using a drying device that alternately conveys the web through rolls arranged in a staggered manner and / or a tenter device that clips and conveys both ends of the web with a clip. As a drying means, hot air is generally blown on both sides of the web, but there is also a means for heating by applying a microwave instead of the wind. Too much drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout, the drying temperature is usually 40 to 250 ° C, preferably 70 to 180 ° C. The drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, and the drying conditions may be appropriately selected according to the type and combination of the solvents used.

  In the drying step after peeling from the casting support surface, the web tends to shrink in the width direction due to evaporation of the solvent. Shrinkage increases as the temperature rapidly dries. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point of view, for example, a method of drying the entire drying process or a part of the process as shown in JP-A-62-46625 while holding the width at both ends of the web with a clip in the width direction (tenter method) Is preferred.

  (6) Winding step: The step of winding the web as a film after the residual solvent amount becomes 2% or less by mass. By setting the residual solvent amount to 0.4% or less, a film having good dimensional stability can be obtained. As a winding method, a generally used method may be used. There are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

  To adjust the film thickness of the fatty acid cellulose ester film, control the dope concentration, pump feed volume, slit gap in the die cap, die extrusion pressure, and casting support speed. It is good to do. Further, it is preferable that the film thickness detecting means is used as a means for making the film thickness uniform, and the programmed feedback information is fed back to each of the above devices for adjustment.

  In the process from immediately after casting through the solution casting film forming method to drying, the atmosphere in the drying apparatus may be air, or may be performed in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. . However, it goes without saying that the danger of the explosion limit of the evaporating solvent in a dry atmosphere must always be taken into account.

  The elution block layer used in the present invention will be described.

  In order to improve the adhesion between the transparent support used in the present invention and the alignment layer for aligning the optically anisotropic layer, it is preferable to provide an elution block layer.

  The elution block layer is an optically anisotropic layer in which an alignment layer or a liquid crystalline compound is present from a transparent support due to the presence of an organic solvent when the alignment layer or the liquid crystalline compound is applied as an organic solvent solution. It means that any of the compounds constituting the transparent support is prevented from eluting into the layer. When an alignment layer or a liquid crystal compound layer is provided as a thin film, it is a preferable technique to prepare and apply an organic solvent solution of these compounds.

  However, in particular, a transparent support such as a cellulose ester film support is composed of a resin and often contains a plasticizer. When the organic solvent that dissolves the resin or plasticizer dissolves the resin or liquid crystalline compound as the alignment layer, diffusion between layers and mixed dissolution between layers can be easily inferred by coating.

  By installing a resin that dissolves in a solvent that is insoluble or difficult to dissolve in the organic solvent during this period, it is possible to suppress interlayer diffusion and interlayer mixing during the coating.

  Moreover, even if the compound is soluble in an organic solvent that dissolves the resin or plasticizer, applying an actinic radiation curable resin on the transparent substrate in the monomer state and simply performing the curing reaction simply applies the resin. Unlike this, a layer having a large number of cross-linked structures can be installed, and when the resin or liquid crystalline compound as the alignment layer is dissolved, diffusion between layers and contamination can be suppressed by coating. Thereby, the orientation of the liquid crystalline compound constituting the optically anisotropic layer can be achieved more stably.

  Providing an elution block layer containing a water-soluble polymer, for example, an organic acid group-containing polymer, on the transparent support used in the present invention is advantageous from the viewpoint of improving the adhesion between the transparent support and the alignment layer. It is big and effective.

  The organic acid group-containing polymer includes, but is not particularly limited to, a structure having an organic acid group in the polymer side chain. Examples of the organic acid group include -COOH group. Examples of such compounds are not particularly limited, but examples include structures represented by general formula [1] or general formula [2] described in JP-A-7-333436. The hydrogen of the —COOH group may be substituted with ammonia or an alkali metal cation (sodium cation, lithium cation). Examples of the monomer unit constituting the polymer having an organic acid group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid. Alternatively, after maleic anhydride is made high molecular weight as a copolymerization monomer, the acid anhydride ring may be opened to obtain an organic acid group.

  One form of the elution block layer according to the present invention is installation of an actinic radiation curable resin layer. The actinic rays are preferably ultraviolet rays because of the availability of light sources and materials.

  Examples of the ultraviolet curable resin include an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, and an ultraviolet curable epoxy resin. I can do it.

  UV curable acrylic urethane resins generally include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter referred to as acrylate) to products obtained by reacting polyester polyols with isocyanate monomers or prepolymers. It can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate (for example, JP-A-59-151110).

  The UV curable polyester acrylate resin can generally be easily obtained by reacting a polyester polyol with 2-hydroxyethyl acrylate or 2-hydroxy acrylate monomer (for example, JP-A-59-151112).

  Specific examples of the ultraviolet curable epoxy acrylate resin include those obtained by reacting epoxy acrylate with an oligomer, a reactive diluent and a photoinitiator added thereto (for example, JP-A-1- No. 105738). As the photoreaction initiator, one or more kinds selected from benzoin derivatives, oxime ketone derivatives, benzophenone derivatives, thioxanthone derivatives and the like can be selected and used.

  Specific examples of ultraviolet curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate. Etc. can be mentioned. These resins are usually used together with known photosensitizers. Moreover, the said photoinitiator can also be used as a photosensitizer. Specific examples include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and the like. Further, when using an epoxy acrylate photoreactant, a sensitizer such as n-butylamine, triethylamine, or tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer contained in the ultraviolet curable resin composition excluding the solvent component that volatilizes after coating and drying is particularly preferably 0.5 to 5% by mass of the composition.

  As a method for applying the UV curable resin composition coating solution, a known method such as a gravure coater, a spinner coater, a wire bar coater, a roll coater, a reverse coater, an extrusion coater or an air doctor coater can be used. The film thickness after curing of the actinic radiation curable resin layer containing ultraviolet rays is suitably 0.05 μm or more and 30 μm or less, and preferably 0.1 to 15 μm. If this dry film thickness is too thin, the elution blockability is lowered, and if the dry film thickness is too thick, the optical compensation film may curl when it is on the film.

  An actinic radiation curable resin has two or more polymerizable groups such as a polymerizable vinyl group, allyl group, acryloyl group, methacryloyl group, isopropenyl group, and epoxy group. Those that form a network structure are preferred. Of these active groups, an acryloyl group, a methacryloyl group or an epoxy group is preferred from the viewpoint of polymerization rate and reactivity, and a polyfunctional monomer or oligomer is preferred. For example, ultraviolet curable acrylic resin, polyester acrylate resin, epoxy acrylate resin, and polyol acrylate resin are preferably used.

  Moreover, as a synthetic polymer used as an elution block layer, you may use what has the characteristic to melt | dissolve the following monomer unit in the said mixed solvent as a single or a copolymer. Specific examples of monomers constituting the polymer include acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, crotonic acid esters, vinyl esters, maleic acid esters, fumaric acid esters, itaconic acid esters, olefins, and styrenes. Etc. More specifically, these monomers include the followings as substituents of acrylic ester derivatives and ester-substituted compounds. Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, amyl group, hexyl group, 2-ethylhexyl group, octyl group, tert-octyl group, dodecyl group, 2-chloroethyl group 2-bromoethyl group, 4-chlorobutyl group, cyanoethyl group, 2-acetoxyethyl group, dimethylaminoethyl group, benzyl group, methoxybenzyl group, 2-chlorocyclohexyl group, cyclohexyl group, furfuryl group, tetrahydrofurfuryl group, phenyl Group, 5-hydroxypentyl group, 2,2-dimethyl-3-hydroxypropyl group, 2-methoxyethyl group, glycidyl group, acetoacetoxyethyl group, 3-methoxybutyl group, 2-ethoxyethyl group, 2-iso- Propoxy group, 2-butoxyethyl group, 2- (2-metho Ciethoxy) ethyl group, 2- (2-butoxyethoxy) ethyl group, ω-methoxyoligooxyethylene group (number of oxyethylene repeating units: n = 7, 9, 11, etc.), ω-hydroxyoligooxyethylene group (oxyethylene) Acrylic esters having a number of repeating units: n = 7, 9, 11, etc.), 1-bromo-2-methoxyethyl group, 1,1-dichloro-2-ethoxyethyl group, etc. And methacrylic acid esters.

  Examples of acrylamide derivatives and methacrylamide derivatives include substituted and unsubstituted acrylamides and methacrylamides, and examples of the substituents of these substituted amides include the following. Methyl group, ethyl group, n-propyl group, n-butyl group, tert-butyl group, n-octyl group, dodecyl group, cyclohexyl group, benzyl group, hydroxymethyl group, methoxyethyl group, dimethylaminopropyl group, phenyl group N-monosubstituted derivatives such as acetoacetoxypropyl group and cyanoethyl group. Examples of N, N-disubstituted derivatives include acrylamide derivatives and methacrylamide derivatives having an N, N-dimethyl group or an N, N-diethyl group.

  Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caprate, vinyl chloroacetate, vinyl methoxyacetate, vinyl phenyl acetate, vinyl benzoate, vinyl salicylate, etc. It is done.

  Examples of olefins include dicyclopentadiene, ethylene, propylene, 1-butene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, and 2,3-dimethylbutadiene.

  Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, and vinyl benzoic acid methyl ester. Can be mentioned.

  Examples of the crotonic acid ester include butyl crotonic acid and hexyl crotonic acid.

  Examples of itaconic acid esters include itaconic acid monomethyl ester, dimethyl itaconate, monobutyl itaconate, diethyl itaconate, and dibutyl itaconate.

  Examples of maleate esters include diethyl fumarate, dimethyl fumarate, and dibutyl fumarate.

  Examples of other monomers include the following.

  Examples of vinyl ketones include methyl vinyl ketone, phenyl vinyl ketone, and methoxyethyl vinyl ketone.

  Heterocycle-containing vinyl monomers include N-vinyl pyridine and 2- and 4-vinyl pyridine, vinyl imidazole, vinyl oxazole, vinyl triazole, N-vinyl-2-pyrrolidone and the like.

  Examples of unsaturated nitriles include acrylonitrile and methacrylonitrile.

  In the above-mentioned polymer, a chemical reactive group such as an unsaturated ethylenic group or an epoxy group may be included in the polymer side chain in order to improve adhesion.

  It is required in the present invention that the above-mentioned polymer can be dissolved in a mixed solvent with at least one organic solvent containing 30% by mass or more, preferably 45% by mass or more of water. As the resin of the elution block layer composed of such a polymer showing solubility, a copolymer containing a ring structure containing a hetero atom in the polymer side chain is preferable, and more preferably 60 masses of N-vinyl-2-pyrrolidone. % Of the copolymer, particularly preferably a homopolymer of N-vinyl-2-pyrrolidone. Polyvinyl alcohol is also preferably used.

  A higher molecular weight of the resin of the elution block layer is preferable from the viewpoint of difficult diffusion to the alignment layer and the liquid crystal layer, and the number average molecular weight is preferably 800,000 or more.

  Moreover, when using the said polymer as an elution block layer, it is preferable that it is 0.1 to 15 micrometer by dry film thickness on a transparent resin substrate. If this dry film thickness is too thin, the elution blockability may be lowered, and if the dry film thickness is too thick, the optical compensation film may be curled when it is on the film.

  In addition to the purpose of preventing the elution of additives such as plasticizers and ultraviolet absorbers from the transparent support, this elution block layer improves the adhesion between the support and the optically anisotropic layer or alignment layer. A function to prevent peeling is also required. For this purpose, it is effective to perform plasma treatment on the transparent resin substrate. Performing plasma treatment while transporting a transparent resin substrate is capable of continuous treatment, and in particular, performing the treatment in a reactive gas atmosphere under atmospheric pressure without applying a vacuum It is preferable to perform the necessary reaction above.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to these.

Example 1
<< Production of long support >>
(Preparation of dope composition)
Cellulose triacetate (average oxidation degree 61.0%) 85kg
Cellulose acetate propionate (acetyl group substitution degree 2.0,
Propionyl group substitution degree 0.8) 15kg
Triphenyl phosphate 5kg
Ethyl phthalyl ethyl glycolate 2kg
Tinuvin 109 0.5kg
Tinuvin 117 0.5kg
Tinuvin 326 0.3kg
Ultrafine silica (Aerosil 200V: manufactured by Nippon Aerosil Co., Ltd.)
0.01kg
430 kg of methylene chloride
90 kg of methanol
The dope composition was put into a closed container, kept at 80 ° C. under pressure and completely dissolved while stirring to obtain a dope composition. Next, the dope composition was filtered, cooled and kept at 35 ° C., and evenly cast on a stainless steel band. After the solvent was evaporated until peeling was possible, the dope composition was peeled off from the stainless steel band. In the drying zone between 50% by mass and 5% by mass of the residual solvent after peeling, the drying is advanced while maintaining the width by the tenter, and further, the residual solvent amount is 1% by mass or less while being conveyed by a large number of rolls. The film was dried to obtain a film having a thickness of 80 μm.

  This cellulose ester film was wound around a glass fiber reinforced resin core having a core diameter of 200 mm in a roll shape having a width of 1 m and a length of 1000 m by a taper tension method to produce a long support. At this time, an embossing ring having a temperature of 250 ° C. was pressed against the end of the film, and the thickness was processed to prevent adhesion between the films.

<Production of elution block layer>
While transporting the following active ray cured layer coating composition on a long support, it is coated with a wire bar and dried, then cured by irradiating with 200 mJ / cm ² (365 nm light amount) of ultraviolet light, and the transported film is wound. I took it. The film thickness of the elution block layer after curing was 3 μm.

(Coating composition for active ray cured layer)
Dipentaerythritol hexaacrylate monomer 70 mass parts Dipentaerythritol hexaacrylate dimer 15 mass parts Dipentaerythritol hexaacrylate trimer component
15 parts by mass Dimethoxybenzophenone Photoinitiator 4 parts by mass Propylene glycol monomethyl ether 75 parts by mass Methyl ethyl ketone (MEK) 75 parts by mass << Coating and orientation treatment of orientation layer 1 >>
A linear alkyl-modified polyvinyl alcohol (MP203; manufactured by Kuraray Co., Ltd.) and a 1% by mass solution of water: methanol = 60: 40 (mass ratio) on an elution block layer coated on a long support. It produced and apply | coated with the extrusion coating machine so that a dry film thickness might be set to 0.2 micrometer. These were dried with 80 ° C. hot air, and then rubbed to form an alignment layer. The rubbing treatment was performed at a direction of 45 ° from the direction of application. This alignment layer can also function as an elution block layer.

<< Coating of liquid crystal layer 1 and fixing treatment of liquid crystal compound orientation >>
LC-101 is 5.0 parts by mass, LC-102 is 4 parts by mass, LC-103 is 1 part by mass, and photopolymerization is started on the alignment film coated on a long support and irradiated with polarized ultraviolet rays. A coating liquid obtained by dissolving 0.1 part by mass of an agent (Irgacure-907; manufactured by Ciba-Geigy) in 4.7 parts by mass of methyl ethyl ketone was applied to the liquid crystal layer by an extrusion coating machine. For drying and orientation, the treatment was performed in a drying zone at 80 ° C. for 24 seconds and in a continuous drying zone at 65 ° C. for 36 seconds to orient the liquid crystalline compound to produce an optically anisotropic layer. Next, it was conveyed to a zone of 20 ° C. and a nitrogen atmosphere (oxygen concentration 1.8%), irradiated with ultraviolet rays having an illuminance of 500 mJ / cm ² using a high-pressure mercury lamp, and the orientation was fixed by a crosslinking reaction. The conveyed film was wound up at room temperature to obtain an optical compensation film sample 101. The film thickness of the optically anisotropic layer was 1.1 μm.

  Next, optical compensation film samples 102 to 108 were obtained in the same manner except that the coating film thickness of the liquid crystal layer was changed as shown in Table 1.

  The optical compensation films 101 to 108 obtained above were evaluated as shown below.

<< Evaluation of unevenness of optical anisotropic layer >>
From the sample coated up to the optically anisotropic layer, samples were cut into 3 cm × 3 cm from a total of 16 locations, 4 locations in the direction of travel of the long support and 4 locations in the width direction at 20 cm intervals. The sample was placed between two polarizing plates arranged so that the light transmission axis was orthogonal. Sample installation direction: A: Sample orientation direction is inclined by 45 ° from the light transmission axis of the polarizing plate. B: The orientation direction of the sample is set parallel to the light transmission axis direction of one polarizing plate. Visually measured the transmission density using X-Rite 310R in the state of A and B, measured five locations in 3 cm × 3 cm, the average value was the density, and the transmission density of the arrangement of A was the transmission density A, The transmission density of the arrangement of B was defined as transmission density B. Further, the value obtained by subtracting the transmission density B from the transmission density A was defined as the contrast. The higher the contrast, the higher the orientation of the liquid crystal layer, and the lower the orientation, the lower the orientation. In addition, the smaller the variation of the transmission density A at the 16 locations, the higher the orientation, and the difference between the maximum value and the minimum value of the transmission density A is regarded as the variation, and the three rank evaluation is visually performed as follows. It was evaluated.

3: Lots of unevenness 2: Slightly unevenness (practical limit level)
1: Unevenness is not seen

  From Table 1, it is clear that the sample of the present invention has less coating unevenness than the comparative sample, and a uniform optically anisotropic layer is obtained.

Example 2
The production conditions were the same as the production of the optical compensation film sample 101 described in Example 1, except that the application conditions of the liquid crystal layer were adjusted to the application conditions (application temperature, application temperature, application environment temperature) shown in Table 2. A liquid crystal layer was applied on the alignment layer, and the contrast and dispersion of the optically anisotropic layer were evaluated according to the following evaluation method.

<< Evaluation of optical anisotropic layer >>
From the sample coated up to the optically anisotropic layer, the sample was cut into 3 cm × 3 cm from a total of 16 points, 4 points in the traveling direction of the long support and 4 points in the width direction at 20 cm intervals. The sample was placed between two polarizing plates arranged so that the light transmission axis was orthogonal. Sample installation direction: A: Sample orientation direction is inclined by 45 ° from the light transmission axis of the polarizing plate. B: The orientation direction of the sample is set parallel to the light transmission axis direction of one polarizing plate. Visually measured the transmission density using X-Rite 310R in the state of A and B, measured five locations in 3 cm × 3 cm, the average value was the density, and the transmission density of the arrangement of A was the transmission density A, The transmission density of the arrangement of B was defined as transmission density B. The value obtained by subtracting the transmission density B from the transmission density A was used as contrast, and the average value of 16 points was shown in the table. The higher the contrast, the higher the orientation of the liquid crystal layer, and the lower the orientation, the lower the orientation. In addition, the smaller the variation in the transmission density A at 16 locations, the higher the orientation.

  The levels and results obtained are shown in Table 2.

  From Table 2, by adjusting the temperature of the coating solution to 15 to 30 ° C., the coating temperature to 15 to 30 ° C., and the coating environment temperature to 20 to 30 ° C., characteristics such as contrast and variation are further improved.

Example 3
Under the same manufacturing conditions as the preparation of the sample 101 of Example 1, an ion blow type static eliminator: BLS Kasuga Denki Co., Ltd. is attached to the feed part of the original winding, and the surface potential of the film is adjusted by the air volume and coating is performed. It was. Using the method described in Example 1, the surface potential, contrast, and variation were evaluated. The results are shown in Table 3.

  From Table 3, it can be seen that the contrast and variation characteristics are further improved by adjusting the surface potential to be smaller than −5 kV.

Example 4
In preparing the optical compensation film sample 101 described in Example 1, the optical compensation film sample 401 to the optical compensation film sample 401 were adjusted in the same manner except that the amount of residual solvent described in Table 4 was adjusted while adjusting the coating liquid supply speed and the coating speed. 408 were prepared, and the contrast and variation were evaluated using the method described in Example 1.

  The amount of residual solvent was measured by the following method by sampling before contacting the first transport roll after coating. The film thickness of the liquid crystal layer was calculated from the coating liquid supply speed and the coating speed. The specific gravity was set as 1, the mass of the liquid crystal layer, and the ratio (%) of the mass of the liquid crystal layer to the residual solvent amount was defined as the residual solvent ratio.

(Residual solvent measurement method)
A film area of 25.0 cm ² is cut out, finely cut to about 5 mm, stored in a dedicated vial, sealed with a septum and an aluminum cap, and then set in a head space sampler HP7694 manufactured by Hewlett-Packard. Gas chromatography (GC) connected to a headspace sampler uses a 5971 model manufactured by Hewlett-Packard Co. equipped with a flame ionization detector (FID) as a detector. The measurement conditions are as follows.

Headspace sampler heating conditions: 120 ° C, 20 minutes GC introduction temperature 150 ° C
Column: DB-624 manufactured by J & W
Temperature rise: 45 ° C, hold for 3 minutes → 100 ° C (8 ° C / min)
A gas chromatogram is obtained using the above measurement conditions. Residual amount of solvent in the film using a calibration curve prepared using the peak area of the chromatogram obtained by measuring in the same manner as above after storing a fixed amount diluted with butanol of methyl ethyl ketone. Got. Table 4 shows the obtained results.

  From Table 4, it is clear that the sample having a residual solvent of 10% or less has better contrast and variation characteristics.

Example 5
In producing the optical compensation film sample 101 described in Example 1, the drying process shown in FIG. 5 (each drying zone length: 2 m) was provided, and the airflow to the film surface was adjusted using the conditions described in Table 5 Then, optical compensation film samples 501 to 510 were prepared in the same manner except that the amount of residual solvent was adjusted to 5.0% by mass. The amount of residual solvent was measured by the method described in Example 4 after sampling at the center of the second drying zone. Contrast and variation were evaluated using the method described in Example 1. Table 5 shows the obtained levels and results.

  From Table 5, it can be seen that by setting the wind speed in the drying zone to 4 m / sec or less, the contrast is good and the variation characteristics are also good.

Example 6
In producing the optical compensation film sample 101 described in Example 1, a drying process apparatus (having five drying zones) as shown in FIG. 5 was used as a drying process, and the temperature of each drying zone (zone length 2 m) was set. Optical compensation film samples 601 to 612 were prepared in the same manner except that the adjustments were made as described in Table 6.

  The temperature of each drying zone was connected to a thermometer by placing a thermocouple at a position 2 cm above the film surface. For the sample 609 alone, the metal belt shown in FIG. 4 was used for conveyance of the second drying zone and the third drying zone.

  The T-NI and T-IN of the liquid crystal layer were measured by the method described using a differential scanning calorimeter (DSC) and found to be T-NI: 76 ° C. and T-IN: 71 ° C. The temperature of the coating chamber was 23 ° C.

  The contrast of the obtained sample was evaluated in the same manner as described in Example 2, and the tilt angle was measured using the method described below.

<Measurement of average tilt angle of optically anisotropic layer>
Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), the angle dependence of the retardation of only the optically anisotropic layer and the transparent support (in the range of −40 ° to + 40 °, measurement is 10) Every °). The optical anisotropic layer was measured in the direction including the maximum refractive index of the optical anisotropic layer. With respect to the angular dependence of the retardation of the entire optically anisotropic layer, the difference in retardation of each angular component of the corresponding transparent support was determined. The observation angle that gives the maximum retardation value depending on the measurement angle is the average tilt angle of the liquid crystalline compound constituting the optically anisotropic layer, and four points in the width direction and four in the width direction at intervals of 20 cm. Samples were cut into 3 cm × 3 cm from a total of 16 locations, and the average tilt angle of each was averaged to obtain the average tilt angle used. In this example, it was confirmed that the observation angle giving the maximum value was shifted from the normal direction (0 °) to the surface of the sample, and the liquid crystalline compound molecules in the optically anisotropic layer were tilted. Moreover, since the minimum value of the retardation value was not 0, it was confirmed that the angle of the optically anisotropic compound molecule was changed in the thickness direction.

  The results obtained are shown in Table 6.

  From Table 6, the contrast and tilt characteristics of the sample produced under the condition that the temperature was not lower than 10 seconds at a temperature not lower than T-IN and not higher than T-NI were good, and there was little disclination. Moreover, when a metal belt is used, there is an advantage that the drying zone can be shortened.

Example 7
In preparing the optical compensation film sample 101 described in Example 1, using the ultraviolet irradiation apparatus used for the coating process of the liquid crystal layer 1 and the fixing process of the alignment of the liquid crystal compound, the oxygen concentration as shown in Table 7 was used. The liquid crystal layer was cured while controlling optical compensation film samples 701 to 705, respectively. The obtained sample was visually evaluated for blocking. The results obtained are shown in Table 7.

  From Table 7, it can be seen that the sample irradiated with ultraviolet rays with the oxygen concentration adjusted to 2% or less does not block at all.

Example 8
In producing the optical compensation film sample 101 described in Example 1, unevenness was detected using a transmitted light measurement device. By recording the portions with different amounts of transmitted light and recording the locations, it was possible to identify the locations of unevenness. The detection of the unevenness described above is effective for manufacturing management of the optical compensation film according to the present invention.

Example 9
The prepared material shown below was used as the upper layer of the sample 102 of Example 1, and the alignment layer 2 and the liquid crystal layer 2 were applied to the upper layer to prepare the optical compensation film 1.

<< Coating of orientation layer 2 and orientation treatment >>
A 1% by mass solution of linear alkyl-modified polyvinyl alcohol (MP203; manufactured by Kuraray Co., Ltd.) in water: methanol = 60: 40 (mass ratio) is prepared on the upper layer of the sample 102, and the dry film thickness is 0.2 μm. It was applied with an extrusion coating machine. These were dried with 80 ° C. hot air, and then rubbed to form an alignment layer. The rubbing treatment direction was 90 ° shifted from that of Example 1 (45 ° direction opposite to the traveling direction).

<< Coating of liquid crystal layer 2 >>
After the alignment layer 2 was applied and aligned, 5.0 parts by mass of LC-101, 4 parts by mass of LC-102, 1 part by mass of LC-103, and a photopolymerization initiator (Irgacure-907; A coating solution obtained by dissolving 0.1 part by mass (manufactured by Geigy Corporation) in 4.7 parts by mass of methyl ethyl ketone was applied by an extrusion coating machine. Drying, orientation, and fixation were performed in the same manner as in Example 1.

  The viewing angle was evaluated using the method described below.

<< Evaluation of viewing angle >>
After pasting the optical compensation film 1 produced above to the polarizing plate produced by the following production method, producing a polarizing plate with an optical compensation film, and peeling off the polarizing plate of the LA-1525J type TFT-TN liquid crystal panel made by NEC. Pasted. Next, the contrast ratio at the time of white / black display was measured using Ez-Contrast of ELDIM, and the angle from the normal direction of the liquid crystal panel showing the contrast of 10 or more was measured for each of the top, bottom, left and right. A wide panel was obtained.

<Polarizing plate manufacturing method>
Two sheets were cut from the long support and subjected to saponification treatment (KOH 2 mol / l 60 ° C. for 60 seconds, followed by washing with water and drying). A polyvinyl alcohol adhesive (3% aqueous solution, dry film thickness 0.01 μm) was applied to these two films, and a polarizer prepared by the following method was bonded to prepare a polarizing plate.

(Manufacturing method of polarizer)
A PVA film having a thickness of 75 μm (Kuraray Vinylon # 7500; manufactured by Kuraray Co., Ltd.) was longitudinally uniaxially stretched (stretching ratio 4 times) to obtain a polarizer substrate. This substrate was immersed in an aqueous solution consisting of 0.2 g / l iodine and 30 g / l potassium iodide at 30 ° C. for 4 minutes. Subsequently, it was immersed in an aqueous solution having a composition of boric acid 70 g / l and potassium iodide 30 g / l at 55 ° C. for 5 minutes, further washed with water at 20 ° C. for 30 seconds, and dried to obtain a polarizer.

Example 10
Similarly, the optical compensation film 1 produced in Example 9 was saponified on one side of the long support (treated with 2 mol / liter KOH, treated at 60 ° C. for 60 seconds, washed with water, and dried). Saponification was performed. Polyvinyl alcohol adhesive (3% aqueous solution, dry film thickness 0.01 μm) was applied to these two films, and the polarizer produced in Example 9 was the same in the orientation direction of the liquid crystal layer 2 and the orientation direction of the polarizer. It stuck so that it might become, and the polarizing plate was produced. The polarizing plate of the NEC LA-1525J type TFT-TN liquid crystal panel was peeled off, and the produced polarizing plate was attached so that the polarization direction was 90 ° with the polarizing plate of the panel. A panel with a wide viewing angle was obtained as in Example 9. By integrating with the polarizing plate, one polarizing plate protective film could be reduced. This can improve productivity and reduce the thickness of the panel.

DESCRIPTION OF SYMBOLS 1 Liquid crystalline compound coating layer 2 Orientation layer 3 Long support body 4 Air introduction port 5, 7 Blower port 6, 6a Conveyance direction 8 Shape adjustment board of a blower port 10 Web 11 Conveyance support roller 12a, 12b Drive roller 13 Drying zone 14 Metal belt 15 Metal plate

Claims (5)

A step of continuously applying a coating liquid containing a solvent and a liquid crystal compound on a long support, a step of drying the liquid crystal layer obtained by the application and aligning the liquid crystal compound, and the liquid crystal Irradiating the layer with active energy rays and polymerizing the liquid crystalline compound,
In the step of applying the coating solution, the step of adjusting the temperature of the coating solution to 15 ° C. to 30 ° C., the coating temperature to 15 ° C. to 30 ° C., the coating environment temperature to 20 to 30 ° C., and the drying and orientation And heating the liquid crystal layer to a temperature equal to or higher than the temperature from the nematic phase to the isotropic phase (T-NI), and then heating to a temperature equal to or lower than the temperature from the isotropic phase to the nematic phase (T-IN). A method for producing an optical compensation film. The step of irradiating the liquid crystal layer with active energy rays irradiates the active energy rays while maintaining the liquid crystal layer below a temperature (T-NI) from the nematic phase to the isotropic phase. 2. A method for producing an optical compensation film according to 1 . Wherein in the step of irradiating an active energy ray to the liquid crystal layer, the oxygen concentration is 2% or less under the conditions, method of manufacturing an optical compensation film according to claim 1 or 2, characterized in that an active energy ray. After the liquid crystal layer is coated on the long support, the polarizing plate is arranged so as to be crossed Nicol, and the long support is passed between the polarizing plates, and the transmitted light is used while being conveyed. method of manufacturing an optical compensation film of any one of claim 1 to 3, characterized by comprising the step of monitoring the state of the unevenness. The production of the optical compensation film according to any one of claims 1 to 4 , wherein the surface potential of the long support is adjusted to -5 to +5 kV at the time of application of the coating liquid containing the liquid crystalline compound. Method.

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