JP5115500B2 - Method for producing optical compensation film - Google Patents

Description

  The present invention relates to a method for producing an optical compensation film having a retardation layer in which rod-like polymerizable liquid crystal compounds are vertically aligned and fixed.

  The IPS (In Plane Switching) type liquid crystal display device is superior in the color, contrast, viewing angle, etc. to the liquid crystal mode of other liquid crystal display devices, such as the TN mode, and is also in the vertical alignment mode (VA, MVA, PVA). The display performance such as the viewing angle is excellent, and the brightness is less affected by the viewing angle, and the response speed in the middle tone is reduced. became.

  Conventionally, the IPS mode used for the IPS mode type liquid crystal display device has a feature that the liquid crystal cell itself does not need to perform viewing angle compensation, and a wide viewing angle can be obtained without a compensation film (see, for example, Patent Document 1). .)

  However, the polarizing plate itself used in the liquid crystal display device generates light leakage when the viewing angle is changed in a 45 ° direction with respect to the absorption axis in a crossed Nicol state, thereby reducing the peripheral contrast of the liquid crystal display device. Is happening.

  Thus, for example, a technique has been devised in which an optical film obtained by stretching a thermoplastic resin film as in Patent Document 2 or Patent Document 3 as an optical compensation film is laminated on a polarizing plate to suppress light leakage of the polarizing plate. . However, these methods are difficult to make into a polarizing plate by roll-to-roll, and a plurality of films are bonded through an adhesive layer or an adhesive layer. The problem of increasing the film thickness occurs. Further, since it is difficult to make the orientation axis of the film uniform in the plane, a problem of color variation (color shift) also occurs.

  With respect to such problems, Patent Documents 4 and 5 propose a method of providing an optical compensation film in which a rod-shaped or disk-shaped liquid crystal material is aligned between a polarizing plate and a liquid crystal cell. . In these optical compensation films, first, a coating film of a polymerizable liquid crystal material is formed on a resin film provided with a rubbing-treated alignment film, and the temperature exceeds the temperature at which the polymerizable liquid crystal material in the coating film exhibits liquid crystal regularity. Heat. After the heating, the temperature of the coating film is cooled to a temperature not higher than the liquid crystal transition point of the polymerizable liquid crystal material. This is a method for producing an optical compensation sheet by irradiating actinic radiation after cooling and polymerizing and curing the polymerizable liquid crystal material.

JP 2000-131700 A Japanese Patent Laying-Open No. 2005-31626 JP 2006-126770 A JP-A-9-73016 JP 2007-72032 A

  However, in the techniques described in Patent Documents 4 and 5, it is necessary to provide a special layer called an alignment film or to perform a rubbing process, which makes the manufacturing process complicated and expensive. In addition, it is difficult to control the temperature after applying the polymerizable liquid crystal material on the alignment film and before irradiating the active radiation. If the heating temperature and the cooling temperature are uneven, the degree of alignment progress can be different, and the alignment can be localized. An insufficient liquid crystal group has so-called alignment defects (alignment unevenness). As a result, it has been found that there may be an optical compensation film that cannot exhibit sufficient functions with respect to peripheral contrast and color variation.

  The present invention has been made in view of the above circumstances, and has an object of having a retardation layer having a rod-like polymerizable liquid crystal compound, having few alignment defects, good contrast when used in a display device, and color shift. It is an object of the present invention to provide a method for producing an optical compensation film with a low content.

  The above object of the present invention can be achieved by the following constitution.

1. Applying a coating solution prepared by dissolving a rod-like polymerizable liquid crystal compound in an organic solvent on a resin film to form a coating film, a drying process for drying the resin film on which the coating film is formed, and the drying In the method for producing an optical compensation film having an active radiation irradiation step of irradiating active radiation to the resin film after the step,
The drying step is a step of setting the temperature of the film surface of the coating film to 10 to 40 ° C. so that the residual solvent ratio of the coating film after the drying step is 3 to 15% by mass,
After the drying step, there is a heat treatment step of heating the film surface temperature of the coating film at a temperature higher than or equal to the phase transition temperature of the polymerizable liquid crystal compound for 5 to 15 seconds,
The actinic radiation irradiation step includes
A method for producing an optical compensation film, wherein after the heat treatment step, the film is irradiated with actinic radiation at a temperature of the coating film surface lower than the phase transition temperature.

  2. 2. The method for producing an optical compensation film as described in 1 above, wherein in the heat treatment step, the temperature of the film surface of the coating film is not less than the phase transition temperature and not more than 120 ° C.

  3. In the heat treatment step, the gas at a position of 5 mm on the surface of the coating film moves in a direction parallel to the surface of the resin film at a relative speed of 1 to 3 m / sec with respect to the resin film. The method for producing an optical compensation film according to 1 or 2 above.

  4). 4. The method for producing an optical compensation film according to any one of 1 to 3, wherein in the heat treatment step, the means for heating the film surface of the coating film is an infrared heater.

  5). 5. The method for producing an optical compensation film according to any one of 1 to 4, wherein the resin film is a cellulose ester film.

  6). 6. The method according to any one of 1 to 5, wherein an intermediate layer is formed on the surface of the resin film to prevent the constituent material of the resin film from oozing into the coating film. A method for producing an optical compensation film.

  It was possible to provide a production method capable of providing an optical compensation film having a retardation layer having a rod-like polymerizable liquid crystal compound, good contrast, and little color shift.

It is the schematic which shows the structure of a liquid crystal display device. It is a schematic plan view for demonstrating an example of the manufacturing method of the optical compensation film of this invention. It is a schematic diagram which shows the specific example of a drying apparatus. It is the schematic which shows an example of the heat processing apparatus.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  FIG. 1 is a schematic diagram showing a configuration of a liquid crystal display device. FIG. 1A is a schematic diagram showing a configuration of a liquid crystal display device having a retardation layer on the viewing side polarizing plate. FIG. 1B is a schematic view showing a configuration of a liquid crystal display device having a retardation layer on a backlight (BL) side polarizing plate.

  The liquid crystal display device shown in FIG. In the figure, reference numeral 1a denotes a liquid crystal display device. The liquid crystal display device 1 a includes a liquid crystal cell 101 sandwiched between a viewing side polarizing plate 102 and a backlight side polarizing plate 103. The liquid crystal cell 101 includes a liquid crystal layer 101c sandwiched between a glass substrate 101a and a glass substrate 101b.

  The viewing side polarizing plate 102 fixes the orientation of the rod-like polymerizable liquid crystal compound on the first protective film 102a, the first polarizing film 102d, and the liquid crystal cell 101 side from the viewing side (shown in the upper part of the figure). The second protective film 102b having the converted retardation layer 102c is included. Note that the second protective film 102b having the retardation layer 102c is referred to as an optical compensation film.

  The backlight side polarizing plate 103 has a configuration including a third protective film 103a, a second polarizing film 103c, and a fourth protective film 103b.

  The retardation layer 102c may be disposed between the first polarizing film 102d and the second protective film 102b.

  The in-plane slow axis b (the arrow direction in the figure) of the second protective film 102b and the alignment direction c (the arrow direction in the figure) of the liquid crystal layer 101c are parallel. The polarizing transmission axis a (the arrow direction in the figure) of the first polarizing film 102d and the second polarizing film 103c and the rubbing axis d (the arrow direction in the figure) of the glass substrates 101a and 101b are in the directions shown in the figure. .

  The liquid crystal display device shown in FIG. In the figure, 1b denotes a liquid crystal display device. The liquid crystal display device 1b includes a viewing side polarizing plate 102 ', a backlight side polarizing plate 103', and a liquid crystal cell 101 'sandwiched between the viewing side polarizing plate 102' and the backlight side polarizing plate 103 '. It is the composition which has. The liquid crystal cell 101 ′ has a configuration including a glass substrate 101′a, a glass substrate 101′b, and a liquid crystal layer 101′c sandwiched therebetween.

  The viewing-side polarizing plate 102 ′ has a fourth protective film 102 ′ a, a second polarizing film 102 ′ c, and a third protective film 102 ′ b from the viewing side (showing the upper side in the figure). It has composition which has.

  The backlight-side polarizing plate 103 'includes a second protective film 103'a having a retardation layer 103'c in which the orientation of the rod-like liquid crystal compound is fixed on the liquid crystal cell 101' side, and a first polarizing film 103'd. And a first protective film 103′b. The second protective film 103′a having the retardation layer 103′c is referred to as an optical compensation film. The retardation layer 103′c may be disposed between the first polarizing film 103′d and the second protective film 103′a.

  The in-plane slow axis b (the arrow direction in the figure) of the second protective film 103'a and the alignment direction c (the arrow direction in the figure) of the liquid crystal layer 101'c are orthogonal. The polarization transmission axis a (the arrow direction in the figure) of the polarizing film and the rubbing axis d (the arrow direction in the figure) of the glass substrate are in the direction shown in the figure. The present invention relates to a method for producing the optical compensation film shown in the figure.

  In the method for producing an optical compensation film according to the present invention, a coating solution in which a rod-like polymerizable liquid crystal compound is dissolved in an organic solvent is applied on a resin film, and a coating film is formed. In the method for producing an optical compensation film having a drying step of drying a resin film and an actinic radiation irradiation step of irradiating actinic radiation to the resin film after the drying step, the drying step determines the temperature of the film surface of the coating film. 10 to 40 ° C., and the residual solvent ratio of the coating film after the drying step is 3 to 15% by mass. After the drying step, the temperature of the film surface of the coating film is changed to that of the polymerizable liquid crystal compound. It has a heat treatment step of heating for 5 to 15 seconds above the phase transition temperature, and the active radiation irradiation step irradiates the active radiation after the heat treatment step when the temperature of the coating film surface is lower than the phase transition temperature of the polymerizable liquid crystal compound This The features. That is, in the conventional method for producing an optical compensation film, after applying a rod-like polymerizable liquid crystal material on a film provided with an alignment film, the liquid crystal layer is once heated to a temperature showing isotropicity in a heating step, Then, it cooled until it became the temperature below the phase transition point temperature of a liquid crystal, it was the vertical alignment, and it was the method of irradiating an active ultraviolet ray after that, and fixing. However, temperature control is difficult and partial orientation defects have occurred. The present inventor noticed that the rod-like polymerizable liquid crystal dissolved in the organic solvent is isotropic in that state, and dried the coating film coated on the resin film at 10 to 40 ° C. After performing the drying process so that the residual solvent ratio of the subsequent coating film is 3 to 15% by mass or less, as the heat treatment process, the film surface temperature is heated to the phase transition temperature of the polymerizable liquid crystal compound for 5 to 15 seconds. Thus, it was found that the rod-like polymerizable liquid crystal is vertically aligned on the resin film without performing an alignment film or a rubbing treatment.

  The phase transition temperature of the polymerizable liquid crystal compound used here is a temperature at which the liquid crystal phase (nematic phase) changes to an isotropic phase (isotropic phase), and is a polymerization in which a plurality of polymerizable liquid crystal compounds are blended. In the case of a polymerizable liquid crystal composition, the temperature is when the phase of the polymerizable liquid crystal composition changes.

  Moreover, the residual solvent ratio of the coating film after a drying process is a ratio of the mass of the residual solvent component with respect to the mass of a coating film.

  In addition, actinic radiation is radiation that exhibits a chemically active action, and specifically means infrared rays, visible rays, ultraviolet rays, X rays, electron beams, α rays, β rays, γ rays, and the like. To do. Of these, ultraviolet rays are particularly preferably used.

  In addition, the term “vertical alignment” as used herein refers to an optical compensation film having a retardation layer formed by a crossed Nicol polarizer when evaluated using a polarizing microscope in order to evaluate the optical retardation of the obtained optical anisotropy. A material that appears black when sandwiched between them and appears white when the optical compensation film having a retardation layer is tilted between crossed Nicol polarizers is defined as being vertically oriented.

  The retardation layer according to the present invention is a retardation layer made of a vertically aligned polymerizable liquid crystal compound in which Ro is in a range of 0 to 10 nm and Rt is in a range of −100 to −400 nm. Furthermore, Ro is more preferably in the range of 0 to 5 nm. In order to make the retardation layer in the above range, the thickness of the retardation layer, actinic radiation irradiation, the temperature during curing, the tilt angle control, and the pretilt angle at the support / air interface can be controlled. preferable.

  In addition, Ro shows in-plane retardation and Rt shows thickness direction retardation. Retardation Ro and Rt are calculated | required by a following formula.

Formula (i) Ro = (nx−ny) × d
Formula (ii) Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the retardation layer surface, ny is the refractive index in the fast axis direction in the retardation layer surface, nz is the refractive index in the thickness direction of the retardation layer (refractive index is 23 Measured at a wavelength of 590 nm under an environment of ° C. and 55% RH), d represents the thickness (nm) of the retardation layer.
For the measurement, an automatic birefringence meter KOBURA 21ADH (manufactured by Oji Scientific Instruments) was used, and the measurement was performed at 23 ° C. and 55% RH at a wavelength of 590 nm.

  FIG. 2 is a schematic plan view for explaining an example of the method for producing the optical compensation film of the present invention. When producing an optical compensation film by the method for producing an optical compensation film of the present invention, an optical compensation film production apparatus 10 schematically shown in FIG. 2 is used. The manufacturing method of the optical compensation film using the manufacturing apparatus 10 includes a resin film supply step 2, a coating step 3, a drying step 4, a heat treatment step 8, a cooling step 5, and an actinic radiation. It has an irradiation process 7 and a recovery process 6. The supplying step 2 uses a feeding device (not shown) that feeds out a roll-shaped resin film 202 in which a resin film 201 that is a belt-like support is wound around a winding core.

  The coating process 3 includes a backup roll 301 that holds the resin film 201 continuously transported from the supply process 2, and a coating head 302 that applies a coating liquid to the continuously transported resin film 201 held by the backup roll 301. And a decompression chamber 303 provided on the upstream side of the coating head 302 in order to stabilize a bead (a pool of coating solution) formed between the coating liquid from the coating head 302 and the resin film 201 at the time of coating. A coating device 304 is used.

  The coating liquid discharged from the coating head 302 contains a rod-like polymerizable liquid crystal material that is cured by actinic radiation and a solvent, and the flow rate thereof can be adjusted by a pump (not shown). The flow rate of the coating liquid discharged from the coating head 302 is determined to be an amount capable of stably forming a coating layer having a predetermined thickness when continuously coated under the conditions of the coating head 302 adjusted in advance.

  The decompression chamber 303 can adjust the degree of decompression. The decompression chamber 303 is connected to a decompression blower (not shown), and the inside is decompressed. The decompression chamber 303 is in a state where there is no air leakage, and the gap between the decompression chamber 303 and the backup roll is adjusted to be narrow so as to form a stable coating liquid bead.

  The drying process 4 uses a drying device 401 that dries the wet coating film applied on the resin film 201 in the coating process 3. Reference numeral 402 denotes a drying gas inlet, and reference numeral 403 denotes a discharge port. The temperature and the air volume of the drying air can be appropriately determined.

  The heat treatment step 8 includes an infrared heater and a heat treatment gas inlet 802 as a heating means 804 for adjusting a film surface temperature for heat-treating the coating film of the resin film 201 having the coating film dried in the drying step 4. And a discharge port 803, and the temperature and the air volume of the coating film surface can be adjusted. The infrared heater is heated from the surface of the film opposite to the coating film.

  In the cooling step 5, the temperature of the resin film 201 having the coating film heat-treated in the heat treatment step 8 can be cooled and adjusted to an appropriate temperature. A cooling device 501 for lowering the temperature is provided, 502 indicates an inlet for cooling air, and 503 indicates an outlet for cooling air. The temperature and the air volume of the cooling air can be appropriately determined. In addition, if the cooling temperature is appropriate without providing the cooling step 5, the cooling device need not be installed.

  In the method for producing an optical compensation film of the present invention, the temperature of the drying process is 10 to 40 ° C., the residual solvent ratio of the coating film after the drying process is 3 to 15% by mass or less, and the film surface of the coating film after the drying process It is characterized by performing a heat treatment step of heating for 5 to 15 seconds above the phase transition temperature of the polymerizable liquid crystal compound using the above temperature. By performing such a process, the isotropic liquid crystal compound in the coating film immediately after coating undergoes vertical alignment through a drying process and a heat treatment process, and is fixed in the active radiation irradiation process, thereby causing alignment defects in the retardation layer. Therefore, it is possible to produce an optical compensation film having a small color shift, excellent productivity, good contrast, and little color shift.

  Since drying at a low temperature has an equiphase liquid state, the phase transition occurs by drying at a low temperature as it is, and it is easy to orient naturally. However, liquid crystal molecules in the vicinity of the surface are difficult to align only by low-temperature drying, and this causes a reduction in contrast. This can be presumed to be because liquid crystal molecules near the surface did not advance due to changes in the surface tension at the gas-liquid interface during drying. For this reason, it was found that the isotropic layer is once formed by heat-treating the vicinity of the surface, and the liquid crystal molecules on the surface are rearranged by reducing the temperature again to reduce alignment defects.

  Further, in the heat treatment step 8, the temperature of the coating film surface is preferably not less than the phase transition temperature of the polymerizable liquid crystal compound and not more than 120 ° C. It is preferable that the surface temperature of the coating film is equal to or higher than the phase transition temperature in that the liquid crystal molecules on the surface are isotropic and are easily rearranged.

  Moreover, it is preferable that the gas in the position of 5 mm on the coating film surface of the resin film 201 in the heat treatment step 8 moves at a relative speed of 1 to 3 m / sec with respect to the resin film 201 in a direction parallel to the resin film surface. .

  If the gas at a position of 5 mm on the coating film surface moves at a relative speed out of the above range with respect to the resin film 201, heat treatment unevenness is likely to occur, resulting in color unevenness.

  Further, in the heat treatment step 8, the means for heating the film surface of the coating film is preferably an infrared heater. It is preferable that the heating means is an infrared heater in that the temperature of liquid crystal molecules in the vicinity of the surface can be quickly raised, and the time for making the isotropic phase temperature can be shortened.

  Moreover, in the drying process 4, it is preferable to give the heated gas to the surface on the opposite side of the coating film surface of the resin film 201. FIG. 3 is a schematic view of a drying device 401a different from the drying device 401 shown in FIG. A drying gas inlet 402 is provided at the top and bottom, and the exhaust gas flow 405 flows in the resin film traveling direction. As a nozzle shape that gives dry gas to the resin film 201, a slit nozzle (nozzle having a slit-like opening shape in the film width direction) 404 is used, but a counter nozzle (a nozzle directed toward the upstream side in the film transport direction). Or a punching nozzle (a nozzle having a large number of punch holes formed on a flat plate) can be used. By adopting a configuration in which the heated gas is applied to the surface opposite to the coating film surface of the resin film 201, the flow of gas on the coating film surface side for drying can be reduced, and the gas on the coating film surface can be reduced. Less disturbing the flow. As a result, a more uniform coating thickness can be obtained and alignment defects can be reduced. Further, when the dry gas is supplied from the lower surface side of the coating film surface, the lift force by the gas can be used, so that the conveying roller can be omitted. Therefore, compared with the case where heated gas is supplied only from the coated surface side in FIG. 2, the contact portion between the resin film and the roller is reduced, the temperature of the resin film during drying can be made more uniform, and orientation defects are reduced. I can do it.

  The coating film applied on the resin film 201 with a certain film thickness is adjusted so that the residual solvent ratio is 3 to 15% by mass through the drying step 4.

  The coating film thus adjusted through the drying process is subjected to a heat treatment in the heat treatment process 8.

  FIG. 4 is a schematic view of a heat treatment apparatus 801a used in a heat treatment step 8 different from FIG. In the heat treatment apparatus 801 in FIG. 2, the plurality of infrared heaters 804 are heated from the opposite side of the coating film surface. However, in the heat treatment apparatus 801 a in FIG. 4, the plurality of infrared heaters 804 are arranged on the coating film surface side. A glass plate is interposed between the heater and the film for heating. Moreover, it has the inlet 802 of the gas for heat processing up and down, and the exhaust gas flow 805 is flowing in the resin film advancing direction. Such a configuration is preferable because an infrared heater can be incorporated in the apparatus in a small space.

  Measure the temperature of the coating film surface with a non-contact thermometer (not shown), adjust the output of the infrared heater and the gas flow rate of the heat treatment gas based on the results, and adjust the film surface temperature of the coating film to a predetermined value. The temperature is controlled so as to be at a temperature. Details of the heat treatment process have been described above, and are omitted here.

  After the heat treatment step, the coating film is irradiated with actinic radiation using the actinic radiation irradiating apparatus 701 in the actinic radiation irradiating step 7 to fix the vertically aligned rod-like polymerizable liquid crystal. If the residual solvent ratio before the actinic radiation irradiation step 7 is less than 3% by mass, the reaction progress rate is slow even if radicals of the polymerization initiator are generated, and a sufficiently fixed film cannot be obtained, resulting in alignment defects. It is easy to generate | occur | produce and it becomes easy to generate | occur | produce a damage | wound on the surface. Further, in the post-recovery recovery step 6, fusion between the films is likely to occur, and the yield of the product is deteriorated.

  On the other hand, if the residual solvent ratio before the actinic radiation irradiation step 7 exceeds 15% by mass, the resin film is deformed and, for example, film thickness unevenness is likely to occur due to slight protrusions or dents.

  Moreover, although the temperature of the coating film just before the active radiation irradiation process 7 should just be less than the phase transition temperature of a polymeric liquid crystal compound, 15-35 degreeC is preferable, More preferably, it is 20-30 degreeC. If the temperature is lower than 15 ° C., the temperature of the coating film is low, the active radiation curing is not sufficiently performed, and immobilization may be insufficient. When the temperature exceeds 40 ° C., the vertical alignment of the rod-like polymerizable liquid crystal is not performed uniformly, and a partial alignment defect occurs.

  The temperature of the coating film surface of the resin film 201 can be measured by a generally known non-contact thermometer such as a laser method or an infrared method. Further, the gas temperature and the air volume in the drying step 4 and the cooling step 5 are not particularly limited, but are adjusted so that the temperature of the coating film surface becomes the above set temperature based on the measurement result by the non-contact temperature system. It ’s fine.

In addition, the actinic radiation irradiation intensity in the actinic radiation irradiation step 7 is preferably 50 to 350 mJ / cm ^{2 in} terms of the integrated light amount (ultraviolet integrated energy amount in the wavelength region of 300 to 390 nm). When the integrated light quantity is less than 50 mJ / cm ² , it may not be sufficiently fixed due to insufficient light quantity. On the other hand, if it exceeds 350 mJ / cm ² , the coating film may be thinly discolored.

Moreover, 200-600 mW / cm < ² > is preferable for the illumination intensity at the time of irradiation. By setting the illuminance within this range, the optical compensation film having good productivity, curing the film at an appropriate speed, and having good alignment with few alignment defects can be obtained.

  As a method for adjusting the illuminance and the integrated light quantity within such a range, the type of actinic radiation irradiation lamp, the type / structure (condensing type or diffusing type) of the reflecting plate, the installation of the diffusing plate, and the transport of the resin film are described later It can be adjusted by appropriately changing the speed, the distance between the lamp and the resin film, and the like.

  The above illuminance measurement can be performed with Eye Graphics Co., Ltd. UV METER UVPF-36, Iida Trade Co., Ltd. ultraviolet intensity meter RMX-3W, VLX-3W, etc., when the active radiation is ultraviolet rays.

  When the active radiation is ultraviolet light, any light source that generates ultraviolet light can be used. For example, commercially available low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultrahigh pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, etc. A lamp can be used.

  The collection step 6 includes a winding device (not shown) that winds up the resin film 201 on which the coating film is formed. Reference numeral 601 denotes a roll-shaped resin film that is wound around and collected by a winding core. a to d denote transport rolls for transporting the resin film 201 having a coating film.

  The optical compensation film obtained by the method for producing an optical compensation film of the present invention described above can obtain a uniformly perpendicularly aligned rod-like polymerizable liquid crystal layer without alignment defects, and this is mounted on a liquid crystal display device. In this case, the contrast is good and the color shift is small.

  The optical compensation film obtained by the production method of the present invention is basically composed of a resin film and a rod-like polymerizable liquid crystal layer formed on the resin film. A configuration in which an intermediate layer is provided is preferable.

  When a coating solution containing a solvent is directly applied onto a resin film, some of the components of the resin film may elute to the coating film side, and the eluted product may cause orientation defects. The eluate is a monomer component of a resin film material or a material added to a resin film such as a plasticizer. Therefore, the eluate can be prevented by forming the intermediate layer on the resin film.

  Next, constituent materials of the optical compensation film used in the method for producing an optical compensation film according to the present invention will be described.

(Bar-shaped polymerizable liquid crystal material)
(Polymerizable liquid crystal compound)
A rod-like polymerizable liquid crystal compound (hereinafter referred to as a unit polymerizable liquid crystal compound) used for the retardation layer can be polymerized by irradiation with predetermined actinic radiation, and the alignment state is fixed in the polymerized state. It has come to be. As the polymerizable liquid crystal compound, any of a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, and a polymerizable liquid crystal polymer can be used, and they can be used by mixing with each other. Since the polymerizable liquid crystal compound can fix the alignment state, the alignment of the liquid crystal can be easily performed at a low temperature, and the alignment state is fixed at the time of use. It can be used regardless of the usage conditions.

  Examples of the polymerizable liquid crystal compound include JP-A-2005-55486, JP-A-2005-173503, JP-A-2005-265889, JP-A-2005-309379, JP-A-2006-227630, JP-A-2006. No. -305242, JP 2007-057607 A, JP 2007-072163 A, JP 2007-119415 A, JP 2007-133299 A, JP 2007-169363 A, JP 2007-191442 A. Polymerizable liquid crystal compounds described in Japanese Patent Publication No.

(Photopolymerization initiator)
In addition to the polymerizable liquid crystal compound, a photopolymerization initiator may be used as necessary. When polymerizing a polymerizable liquid crystal compound by electron beam irradiation, a photopolymerization initiator may be unnecessary, but it is generally used. This is because, for example, in the case of curing by ultraviolet (UV) irradiation, a photopolymerization initiator is usually used for promoting polymerization.

  Photopolymerization initiators include benzyl (also called bibenzoyl), benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4-benzoyl-4'-methyldiphenyl sulfide, benzyl methyl ketal, dimethylamino Methylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3′-dimethyl-4-methoxybenzophenone, methylobenzoylformate, 2-methyl-1- (4 -(Methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1- (4-dodecylphenyl) -2- Droxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2- Examples include methylpropan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, or 1-chloro-4-propoxythioxanthone. I can do it. In general, the addition amount of the photopolymerization initiator is preferably 0.01% to 20%, more preferably 0.1% to 10%, and still more preferably 0.5% to 5%. The polymerizable liquid crystal compound according to the present invention can be added. In addition to the photopolymerization initiator, a sensitizer can be added as long as the object of the present invention is not impaired.

(Solvent used in coating solution in which polymerizable liquid crystal compound is dissolved in organic solvent)
The solvent is not particularly limited as long as it is a solvent capable of dissolving the above-described polymerizable liquid crystal compound and the like and does not deteriorate the properties of the transparent resin film. Specifically, benzene, Hydrocarbons such as toluene, xylene, n-butylbenzene, diethylbenzene, tetralin; ethers such as methoxybenzene, 1,2-dimethoxybenzene, diethylene glycol dimethyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or 2,4- Ketones such as pentanedione; ethyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, or γ-butyrolactone Ters; Amide solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone, dimethylformamide, or dimethylacetamide; chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, tritrichloroethylene, tetrachloroethylene, chlorobenzene, or orthodichlorobenzene Halogen solvents such as t-butyl alcohol, diacetone alcohol, glycerin, monoacetin, ethylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl ether, ethyl cellosolve, or butyl cellosolve; phenols, One or two or more phenols such as parachlorophenol can be used.

  If only a single type of solvent is used, the solubility of the polymerizable liquid crystal compound or the like may be insufficient, or the film may be eroded as described above. However, this inconvenience can be avoided by using a mixture of two or more solvents. Among the above-mentioned solvents, preferred as a single solvent are a hydrocarbon solvent and a glycol monoether acetate solvent, and preferred as a mixed solvent is a mixed system of ethers or ketones and glycols. It is. The concentration of the solution depends on the solubility of the polymerizable liquid crystal compound and the like and the film thickness of the liquid crystal layer to be produced, and thus cannot be defined unconditionally, but is usually preferably 1% to 60%, more preferably 3%. It is adjusted within a range of ˜40%.

(Other additives)
To the coating solution in which the polymerizable liquid crystal compound according to the present invention is dissolved in an organic solvent, compounds other than those described above can be added within a range that does not impair the object of the present invention. Examples of compounds that can be added include polyester (meth) acrylates obtained by reacting (meth) acrylic acid with polyester prepolymers obtained by condensing polyhydric alcohols with monobasic acids or polybasic acids; polyol groups; A polyurethane (meth) acrylate obtained by reacting a compound having two isocyanate groups with each other and then reacting the reaction product with (meth) acrylic acid; bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak Type epoxy resin, polycarboxylic acid polyglycidyl ester, polyol polyglycidyl ether, aliphatic or cycloaliphatic epoxy resin, amine epoxy resin, triphenolmethane type epoxy resin, dihydroxybenzene type epoxy resin and the like (meth) Acry Photopolymerizable compound in epoxy (meth) acrylate obtained by reacting an acid, or a photopolymerizable liquid crystal compound, and the like having an acrylic group or methacrylic group. The amount of the compound added in the coating solution in which the polymerizable liquid crystal compound according to the present invention is dissolved in an organic solvent is selected within a range that does not impair the purpose of the present invention, and is generally a composition that forms a liquid crystal layer. It is preferably 40% or less of the product, more preferably 20% or less. The addition of these compounds improves the curability of the polymerizable liquid crystal compound according to the present invention, increases the mechanical strength of the resulting liquid crystal layer, and improves its stability.

(Surfactant used in coating solution in which polymerizable liquid crystal compound is dissolved in organic solvent)
A surfactant or the like can be added to the coating solution obtained by dissolving the polymerizable liquid crystal compound according to the present invention in an organic solvent in order to facilitate coating. Examples of surfactants that can be added include cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides, polyamine derivatives, etc .; polyoxyethylene-polyoxypropylene condensates, primary or secondary Alcohol ethoxylate, alkylphenol ethoxylate, polyethylene glycol and its ester, sodium lauryl sulfate, ammonium lauryl sulfate, amines of lauryl sulfate, alkyl-substituted aromatic sulfonate, alkyl phosphate, aliphatic or aromatic sulfonic acid formalin condensate, etc. Anionic surfactants; amphoteric surfactants such as laurylamidopropylbetaine and laurylaminoacetic acid betaine; nonionic interfaces such as polyethylene glycol fatty acid esters and polyoxyethylene alkylamine Perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl group / hydrophilic group-containing oligomer, perfluoroalkyl / lipophilic group Fluorine-based surfactants such as oligomeric perfluoroalkyl group-containing urethanes may be mentioned. The amount of the surfactant added depends on the type of surfactant, the type of liquid crystal material, the type of solvent, and the type of alignment film on which the solution is applied. 10 mass ppm-10 mass% are preferable, More preferably, it is 100 mass ppm-5 mass%, More preferably, it is the range of 0.1-1 mass%.

(Resin film)
The resin film (base material) used for the optical compensation film according to the present invention is preferably easy to manufacture and optically transparent, and particularly preferably a transparent resin film. Transparent means that the transmittance of visible light is 60% or more, preferably 80% or more, particularly preferably 90% or more.

  Although it will not specifically limit if it has said property, For example, cellulose ester-type films, such as a cellulose diacetate film, a cellulose triacetate film, a cellulose acetate propionate film, a cellulose acetate butyrate film, a polyester-type film, a polycarbonate Film, polyarylate film, polysulfone (including polyethersulfone) film, polyester film such as polyethylene terephthalate and polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol Film, syndiotactic polystyrene film, polycarbonate film, nor Runen resin film, a polymethylpentene film, a polyether ketone film, polyether ketone imide film, a polyamide film, a fluororesin film, a nylon film, polymethyl methacrylate film, may be mentioned acrylic film or a glass plate or the like. Of these, norbornene resin films and cellulose ester films are preferred. The norbornene-based resin film is an amorphous polyolefin film having a norbornene structure, and examples thereof include APO manufactured by Mitsui Petrochemical Co., Ltd., ZEONEX manufactured by Nippon Zeon Co., Ltd., and ARTON manufactured by JSR Corporation.

  Among these, as the resin film according to the present invention, it is preferable to use a cellulose ester film, and it is particularly preferable to use a cellulose ester film mainly containing a specific cellulose ester described later. As the cellulose ester, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate phthalate are preferable, and among these, cellulose acetate and cellulose acetate propionate are preferably used. As a commercially available cellulose ester film, for example, Konica Minoltack KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC12UR, KC4FR, KC8UY-HA, HC8UX However, it is preferably used from the viewpoints of production, cost, transparency, adhesion and the like. These films may be films produced by melt casting film formation or films produced by solution casting film formation.

<Cellulose ester>
The cellulose ester used for the cellulose ester film used in the optical compensation film according to the present invention will be described in detail. As the cellulose ester, an aliphatic carboxylic acid ester having about 2 to 22 carbon atoms, an aromatic carboxylic acid ester, or a mixed ester of an aliphatic carboxylic acid ester and an aromatic carboxylic acid ester is preferably used, and in particular, a lower fatty acid ester of cellulose. It is preferable. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. Specifically, it is described in cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate phthalate, etc., JP-A Nos. 10-45804, 8-231761, U.S. Pat. No. 2,319,052, and the like. And mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate. Among the above descriptions, the lower fatty acid ester of cellulose particularly preferably used is cellulose acetate propionate.

  The cellulose ester has an acyl group having 2 to 22 carbon atoms as a substituent, a cellulose that simultaneously satisfies the following formulas 1 and 2 when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group is Y: Ester.

Formula 1 2.00 ≦ X + Y ≦ 2.60
Formula 2 0.10 ≦ Y ≦ 1.00
Among them, 2.30 ≦ X + Y ≦ 2.55 is preferable, and 2.40 ≦ X + Y ≦ 2.55 is more preferable. Moreover, 0.50 ≦ Y ≦ 0.90 is preferable, and 0.70 ≦ Y ≦ 0.90 is more preferable.

  The portion not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods. Moreover, these acyl group substitution degrees can be measured according to the method prescribed | regulated to ASTM-D817-96.

  As the cellulose ester, cellulose ester synthesized from cotton linter, wood pulp, kenaf or the like as a raw material can be used alone or in combination. In particular, it is preferable to use a cotton linter (hereinafter sometimes simply referred to as a linter) or a cellulose ester synthesized from wood pulp alone or in combination.

  Moreover, the cellulose ester obtained from these can be mixed and used in arbitrary ratios, respectively. These cellulose esters are prepared by using an organic acid such as acetic acid or an organic solvent such as methylene chloride when sulfuric acid is used as the acylating agent (acetic anhydride, propionic anhydride, butyric anhydride). It can obtain by making it react by a conventional method using a protic catalyst like.

  In the case of acetylcellulose, it is necessary to extend the time for the acetylation reaction in order to increase the acetylation rate. However, if the reaction time is too long, decomposition proceeds at the same time, and polymer chain scission or acetyl group decomposition occurs, leading to undesirable results. Therefore, it is necessary to set the reaction time within a certain range in order to increase the degree of acetylation and suppress decomposition to some extent. It is not appropriate to define the reaction time because the reaction conditions are various and greatly change depending on the reaction apparatus, equipment and other conditions. As the decomposition of the polymer progresses, the molecular weight distribution becomes wider. Therefore, in the case of cellulose ester, the degree of decomposition can be defined by the value of weight average molecular weight (Mw) / number average molecular weight (Mn) that is usually used. That is, in the process of acetylation of cellulose triacetate, the weight average molecular weight used as one index of the reaction degree for allowing the acetylation reaction to be carried out for a sufficient time for acetylation without being excessively decomposed too much. The value of (Mw) / number average molecular weight (Mn) can be used.

  The ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose ester according to the present invention is preferably 1.4 to 3.0. In the present invention, the cellulose ester film may contain, as a material, a cellulose ester having a Mw / Mn value of 1.4 to 3.0, but the cellulose ester contained in the film (preferably cellulose triacetate). (Or cellulose acetate propionate) The value of Mw / Mn of the whole is more preferably in the range of 1.4 to 3.0. In the synthesis process of cellulose ester, it is difficult to make it less than 1.4, and cellulose ester having a uniform molecular weight can be obtained by fractionation by gel filtration or the like. However, this method is very expensive. Moreover, it is preferable that it is 3.0 or less because the flatness is easily maintained. In addition, More preferably, it is 1.7-2.2.

  The molecular weight of the cellulose ester according to the present invention is preferably 80000 to 200000 in terms of number average molecular weight (Mn). More preferred are 100,000 to 200,000, particularly preferably 150,000 to 200,000.

  The average molecular weight and molecular weight distribution of the cellulose ester can be measured by a known method using high performance liquid chromatography. Using this, the number average molecular weight and the weight average molecular weight can be calculated, and the ratio (Mw / Mn) can be calculated.

  The measurement conditions are as follows.

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

  The method for producing cellulose ester can be obtained by the method described in JP-A-10-45804.

  Cellulose esters are also affected by trace metal components in cellulose esters. These are considered to be related to water used in the production process, but it is preferable that there are few components that can become insoluble nuclei, and metal ions such as iron, calcium, and magnesium contain organic acidic groups. Insoluble matter may be formed by salt formation with a polymer degradation product or the like that may be present, and it is preferable that the amount is small. The iron (Fe) component is preferably 1 ppm or less. About calcium (Ca) component, it is contained in a lot of ground water and river water, etc., and it becomes hard water, and it is unsuitable as drinking water. Coordination compounds with ligands, that is, complexes are easily formed, and scum (insoluble starch, turbidity) derived from many insoluble calcium is formed.

  The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. The magnesium (Mg) component is preferably in the range of 0 to 70 ppm, particularly preferably 0 to 20 ppm, since too much will cause insoluble matter. Metal components such as iron (Fe) content, calcium (Ca) content, magnesium (Mg) content, etc. are pre-processed by completely digesting cellulose ester with micro digest wet cracking equipment (sulfuric acid decomposition) and alkali melting. After performing, it can obtain | require by performing an analysis using ICP-AES (inductively coupled plasma emission spectroscopy analyzer).

  The cellulose ester film according to the present invention preferably has a refractive index of 1.45 to 1.60 at 550 nm. As a method for measuring the refractive index of the film, an Abbe refractometer is used, and measurement is performed based on Japanese Industrial Standard JIS K 7105.

<Additive>
The cellulose ester film can contain additives such as a plasticizer, an ultraviolet absorber, an antioxidant, and a matting agent.

  As described above, the cellulose ester film used in the third protective film according to the present invention preferably has a retardation in the range of 0 to 5 nm and Rt in the range of -10 to 10 nm. In order to obtain the above numerical range, if the third protective film is a cellulose ester, it is produced by melt film formation, or it is maintained by solution film formation at a temperature above the glass transition point for 15 seconds or more. Alternatively, it is preferable to add an additive having a birefringence developing property opposite to that of the cellulose ester. Especially, in order to adjust retardation in the said range, it is preferable to contain the following acrylic polymer.

<Acrylic polymer>
The cellulose ester film used for the third protective film according to the present invention preferably contains an acrylic polymer having a weight average molecular weight of 500 or more and 30000 or less, which exhibits negative orientation birefringence with respect to the stretching direction. The acrylic polymer is preferably an acrylic polymer having an aromatic ring in the side chain or an acrylic polymer having a cyclohexyl group in the side chain.

  By controlling the composition of the acrylic polymer with a weight average molecular weight of the acrylic polymer of 500 or more and 30000 or less, the compatibility between the cellulose ester and the acrylic polymer can be improved.

  In particular, for an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, or an acrylic polymer having a cyclohexyl group in the side chain, if the weight average molecular weight is 500 to 10,000, in addition to the above, The cellulose ester film has excellent transparency and extremely low moisture permeability, and exhibits excellent performance as a protective film for polarizing plates.

  Since the acrylic polymer has a weight average molecular weight of 500 or more and 30000 or less, it is considered to be between the oligomer and the low molecular weight polymer. In order to synthesize such a polymer, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can make the molecular weight as uniform as possible by a method that does not increase the molecular weight too much.

  As the polymerization method, a method using a peroxide polymerization initiator such as cumene peroxide or t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than usual polymerization, a mercapto compound in addition to the polymerization initiator, A method using a chain transfer agent such as carbon tetrachloride, a method using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator, and further disclosed in JP 2000-128911 A or 2000-344823 Examples thereof include a method of bulk polymerization using a compound having one thiol group and a secondary hydroxyl group, or a polymerization catalyst in which the compound and an organometallic compound are used in combination. In particular, the method described in the publication is preferable. Although the monomer as a monomer unit which comprises a polymer is mentioned below, it is not limited to this.

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

  An acrylic polymer (simply referred to as an acrylic polymer) refers to a homopolymer or copolymer of acrylic acid or methacrylic acid alkyl ester that does not have a monomer unit having an aromatic ring or a cyclohexyl group. An acrylic polymer having an aromatic ring in the side chain is an acrylic polymer that always contains an acrylic acid or methacrylic acid ester monomer unit having an aromatic ring.

  An acrylic polymer having a cyclohexyl group in the side chain is an acrylic polymer containing an acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group.

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

  The acrylic polymer is a homopolymer or copolymer of the above-mentioned monomers, but the acrylic acid methyl ester monomer unit preferably has 30% by mass or more, and the methacrylic acid methyl ester monomer unit has 40% by mass or more. preferable. In particular, a homopolymer of methyl acrylate or methyl methacrylate is preferred.

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

  Among the acrylic polymers having an aromatic ring in the side chain, the acrylic acid or methacrylic acid ester monomer unit having an aromatic ring has 20 to 40% by mass, and the acrylic acid or methacrylic acid methyl ester monomer unit is 50 to 80% by mass. % Is preferable. The polymer preferably has 2 to 20% by mass of acrylic acid or methacrylic acid ester monomer units having a hydroxyl group.

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

  In the acrylic polymer having a cyclohexyl group in the side chain, the acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group has 20 to 40% by mass and preferably 50 to 80% by mass. Moreover, it is preferable to have 2-20 mass% of acrylic acid or methacrylic acid ester monomer units having a hydroxyl group in the polymer.

  A polymer obtained by polymerizing the above ethylenically unsaturated monomer, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, and an acrylic polymer having a cyclohexyl group in the side chain are all excellent in compatibility with the cellulose resin.

  In the case of an acrylic acid or methacrylic acid ester monomer having these hydroxyl groups, it is not a homopolymer but a constituent unit of a copolymer. In this case, it is preferable that the acrylic acid or methacrylic acid ester monomer unit having a hydroxyl group is contained in the acrylic polymer in an amount of 2 to 20% by mass. A polymer having a hydroxyl group in the side chain can also be preferably used. The monomer unit having a hydroxyl group is the same as the monomer described above, but acrylic acid or methacrylic acid ester is preferable. For example, acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3 -Hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, or these acrylic acids. The thing replaced by methacrylic acid can be mentioned, Preferably, it is acrylic acid-2-hydroxyethyl and methacrylic acid-2-hydroxyethyl. The acrylic acid ester or methacrylic acid ester monomer unit having a hydroxyl group in the polymer is preferably contained in the polymer in an amount of 2 to 20% by mass, more preferably 2 to 10% by mass.

  A polymer containing 2 to 20% by mass of the above-mentioned monomer unit having a hydroxyl group, of course, is excellent in compatibility with cellulose ester, retention, dimensional stability, low moisture permeability, and polarized light. It is particularly excellent in adhesiveness with a polarizer as a plate protective film, and has the effect of improving the durability of the polarizing plate.

  The method of having a hydroxyl group at at least one terminal of the main chain of the acrylic polymer is not particularly limited as long as it has a hydroxyl group at the terminal of the main chain, but azobis (2-hydroxyethylbutyrate) A method using a radical polymerization initiator having such a hydroxyl group, a method using a chain transfer agent having a hydroxyl group such as 2-mercaptoethanol, a method using a polymerization terminator having a hydroxyl group, and terminating a hydroxyl group by living ion polymerization. Or a compound having one thiol group and a secondary hydroxyl group as disclosed in JP-A No. 2000-128911 or 2000-344823, or a combination of the compound and an organometallic compound. It can be obtained by a bulk polymerization method using a polymerization catalyst, and the method described in the publication is particularly preferred. .

  The polymer produced by the method related to the description in this publication is commercially available as Act Flow Series manufactured by Soken Chemical Co., Ltd., and can be preferably used. The polymer having a hydroxyl group at the terminal and / or the polymer having a hydroxyl group in a side chain has an effect of significantly improving the compatibility and transparency of the polymer.

  Furthermore, a polymer using styrene as an ethylenically unsaturated monomer exhibiting negative orientation birefringence with respect to the stretching direction is preferred in order to develop negative refraction. Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, and vinyl benzoic acid methyl ester. Although it is mentioned, it is not limited to these.

  It may be copolymerized with the exemplified monomers listed as the unsaturated ethylenic monomer, or may be used by being dissolved in a cellulose ester using two or more of the above polymers for the purpose of controlling birefringence.

  Furthermore, the cellulose ester film according to the present invention includes an ethylenically unsaturated monomer Xa that does not have an aromatic ring and a hydrophilic group in the molecule, and an ethylenically unsaturated monomer that does not have an aromatic ring in the molecule and has a hydrophilic group. A weight average molecular weight of 500 to 3,000 obtained by polymerizing a polymer X having a weight average molecular weight of 5,000 to 30,000 obtained by copolymerization with Xb, and more preferably an ethylenically unsaturated monomer Ya having no aromatic ring. It is preferable to contain the following polymer Y.

(Polymer X, Polymer Y)
Polymer X is obtained by copolymerizing ethylenically unsaturated monomer Xa having no aromatic ring and hydrophilic group in the molecule and ethylenically unsaturated monomer Xb having no aromatic ring and having a hydrophilic group in the molecule. The obtained polymer having a weight average molecular weight of 5,000 to 30,000. Preferably, Xa is an acrylic or methacrylic monomer that does not have an aromatic ring and a hydrophilic group in the molecule, and Xb is an acrylic or methacrylic monomer that does not have an aromatic ring in the molecule and has a hydrophilic group.

  The polymer X is represented by the following general formula (X).

Formula (X)
-(Xa) m- (Xb) n- (Xc) p-
More preferably, it is a polymer represented by the following general formula (X-1).

Formula (X-1)
_{- [CH 2 -C (-R1)} (- CO 2 R2)] m- [CH 2 -C (-R3) (- CO 2 R4-OH) -] n- [Xc] p-
(In the formula, R 1, R ₃ and R 5 represent H or CH _3. R ₂ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R 4 and R 6 represent —CH ₂ — or —C ₂ H ₄ —. Or -C ₃ H _6- , wherein Xc represents a monomer unit polymerizable to Xa and Xb, m, n and p represent molar composition ratios, provided that m ≠ 0, n ≠ 0, m + n + p = 100.)
Although the monomer as a monomer unit which comprises the polymer X is mentioned below, it is not limited to this.

  In X, the hydrophilic group means a group having a hydroxyl group or an ethylene oxide chain.

  Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and no hydrophilic group in the molecule include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), and butyl acrylate (n-, i- , S-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n- I-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-ethoxyethyl) ) Or the like, or those obtained by replacing the acrylic ester with a methacrylic ester. Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate (i-, n-) are preferable.

  The ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydrophilic group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxyl group, for example, acrylic acid (2-hydroxyethyl), List acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), or those in which these acrylic acids are replaced by methacrylic acid. Preferred are acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl).

  Xc is not particularly limited as long as it is an ethylenically unsaturated monomer other than Xa and Xb and can be copolymerized, but preferably has no aromatic ring.

  The molar composition ratio m: n of Xa, Xb and Xc is preferably in the range of 99: 1 to 65:35, more preferably in the range of 95: 5 to 75:25. P of Xc is 0-10. Xc may be a plurality of monomer units.

  When the molar composition ratio of Xa is large, the compatibility with the cellulose ester is improved, but the retardation value Rt in the film thickness direction is increased. When the molar composition ratio of Xb is large, the compatibility is deteriorated, but the effect of reducing Rt is high. Further, if the molar composition ratio of Xb exceeds the above range, haze tends to occur during film formation, and it is preferable to optimize these and determine the molar composition ratio of Xa and Xb.

  As for the molecular weight of the polymer X, the weight average molecular weight is from 5,000 to 30,000, more preferably from 8,000 to 25,000.

  By setting the weight average molecular weight to 5,000 or more, it is preferable because the cellulose ester film has advantages such as less dimensional change under high temperature and high humidity and less curling as a polarizing plate protective film. When the weight average molecular weight is within 30000, the compatibility with the cellulose ester is further improved, and bleeding out under high temperature and high humidity, and further haze generation immediately after film formation is suppressed.

  The weight average molecular weight of the polymer X can be adjusted by a known molecular weight adjusting method. Examples of such a molecular weight adjusting method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, octyl thioglycolate, and the like. The polymerization temperature is usually from room temperature to 130 ° C., preferably from 50 ° C. to 100 ° C., and this temperature or the polymerization reaction time can be adjusted.

  The measuring method of a weight average molecular weight can be based on the following method.

(Weight average molecular weight measurement method)
The weight average molecular weight Mw was measured using gel permeation chromatography.

  The measurement conditions are as follows.

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

  The polymer Y is a polymer having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring.

  A weight average molecular weight of 500 or more is preferable because the residual monomer of the polymer is reduced. Moreover, it is preferable to set it as 3000 or less in order to maintain retardation value Rt fall performance.

  Ya is preferably an acrylic or methacrylic monomer having no aromatic ring.

  The polymer Y is represented by the following general formula (Y).

General formula (Y)
-(Ya) k- (Yb) q-
More preferably, it is a polymer represented by the following general formula (Y-1).

General formula (Y-1)
_{- [CH 2 -C (-R5)} (- CO 2 R6)] k- [Yb] q-
(Wherein, R5 is, .Yb .R6 representing H or CH ₃ is representing an alkyl group or a cycloalkyl group having 1 to 12 carbon atoms, .k and q represents the Ya and copolymerizable monomer units, Represents a molar composition ratio, provided that k ≠ 0 and k + q = 100.)
Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Yb may be plural. k + q = 100, q is preferably 0-30.

  The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing an ethylenically unsaturated monomer having no aromatic ring is, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i- , N-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (N-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid (2- Ethyl hexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropiyl) ), Acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), methacrylic acid ester, the above acrylic acid ester changed to methacrylic acid ester; unsaturated acid, for example, acrylic acid, methacrylic acid , Maleic anhydride, crotonic acid, itaconic acid and the like.

  Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, and vinyl caproate. Vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate and the like are preferred. Yb may be plural.

  In order to synthesize the polymers X and Y, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can make the molecular weights as uniform as possible without increasing the molecular weight. Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method using a chain transfer agent such as carbon tetrachloride, a method using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator, and further JP-A-2000-128911 or 2000-344823. And a method of bulk polymerization using a compound having one thiol group and a secondary hydroxyl group, or a polymerization catalyst in which the compound and an organometallic compound are used in combination. In particular, a polymerization method using a compound having a thiol group and a secondary hydroxyl group in the molecule as a chain transfer agent is preferable.

  In this case, the terminal of the polymer X and the polymer Y has a hydroxyl group and a thioether resulting from the polymerization catalyst and the chain transfer agent. By this terminal residue, the compatibility between the polymers X and Y and the cellulose ester can be adjusted.

  The hydroxyl values of the polymers X and Y are preferably 30 to 150 [mg KOH / g].

(Measurement method of hydroxyl value)
This measurement conforms to JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxyl group when 1 g of a sample is acetylated. Specifically, sample Xg (about 1 g) is precisely weighed in a flask, and 20 ml of an acetylating reagent (a solution obtained by adding pyridine to 20 ml of acetic anhydride to 400 ml) is accurately added thereto. An air cooling tube is attached to the mouth of the flask and heated in a glycerin bath at 95-100 ° C.

  After 1 hour and 30 minutes, the mixture is cooled, 1 ml of purified water is added from an air condenser, and acetic anhydride is decomposed into acetic acid. Next, titration is performed with a 0.5 mol / L potassium hydroxide ethanol solution using a potentiometric titrator, and the inflection point of the obtained titration curve is set as the end point. Further, as a blank test, titration is performed without a sample, and an inflection point of the titration curve is obtained.

  The hydroxyl value is calculated by the following formula.

Hydroxyl value = {(BC) × f × 28.05 / X} + D
(Wherein B is the amount of 0.5 mol / L potassium hydroxide ethanol solution used in the blank test (ml), and C is the amount of 0.5 mol / L potassium hydroxide ethanol solution used in the titration (ml). F is a factor of 0.5 mol / L potassium hydroxide ethanol solution, D is an acid value, and 28.05 is 1/2 of 1 mol amount of potassium hydroxide 56.11)
All of the above-mentioned X polymer polymers Y have excellent compatibility with cellulose esters, excellent productivity without evaporation and volatilization, good retention as a protective film for polarizing plates, low moisture permeability, and excellent dimensional stability. ing.

The content of the polymer X and the polymer Y in the cellulose ester film is preferably in a range satisfying the following formulas (a) and (b). When the content of the polymer X is Xg (mass% = the mass of the polymer X / the mass of the cellulose ester × 100) and the content of the polymer Y is Yg (mass%),
Formula (a) 5 ≦ Xg + Yg ≦ 35 (mass%)
Formula (b) 0.05 ≦ Yg / (Xg + Yg) ≦ 0.4
A preferable range of the formula (a) is 10 to 25% by mass.

  If the total amount of the polymer X and the polymer Y is 5% by mass or more, the polymer X and the polymer Y sufficiently act to reduce the retardation value Rt. Moreover, if it is 35 mass% or less as a total amount, adhesiveness with polarizer PVA is favorable.

  The polymer X and the polymer Y can be directly added and dissolved as a material constituting the dope liquid described later, or can be added to the dope liquid after being previously dissolved in an organic solvent for dissolving the cellulose ester.

<Other additives>
The cellulose ester film may contain an additive that can be added to a normal cellulose ester film. Examples of these additives include plasticizers, ultraviolet absorbers, and fine particles.

  Examples of plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, glycolate plasticizers, citrate ester plasticizers, and polyesters. A plasticizer, a polyhydric alcohol ester plasticizer, and the like can be preferably used.

  For phosphate plasticizers, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate ester plasticizers, diethyl phthalate, dimethoxy Ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, diphenyl phthalate, dicyclohexyl phthalate, and other trimellitic acid plasticizers include tributyl trimellitate, triphenyl trimellitate, triethyl For pyromellitic acid ester plasticizers such as trimellitate, tetrabutylpyromellitate, In the case of glycolate plasticizers such as lupyromelitate and tetraethylpyromellitate, triacetin, tributyrin, ethylphthalylethyl glycolate, methylphthalylethylglycolate, butylphthalylbutylglycolate, etc. Citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n- (2-ethylhexyl) citrate and the like can be preferably used. Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters.

  As the polyester plasticizer, a copolymer of a dibasic acid such as an aliphatic dibasic acid, an alicyclic dibasic acid, or an aromatic dibasic acid and a glycol can be used. The aliphatic dibasic acid is not particularly limited, and adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyl dicarboxylic acid and the like can be used. As the glycol, ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol and the like can be used. These dibasic acids and glycols may be used alone or in combination of two or more.

  The polyhydric alcohol ester plasticizer comprises an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid. Examples of preferred polyhydric alcohols include the following. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, 2-n-butyl-2-ethyl- 1,3-propanediol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, and the like can be raised. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable. There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following. As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid. Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, olein Unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid can be raised. Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof. Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. Aromatic monocarboxylic acids or derivatives thereof can be raised. Particularly preferred is benzoic acid. The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose ester.

  The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified with a carboxylic acid, or a part of the OH groups may be left as they are. These plasticizers are preferably used alone or in combination. The amount of these plasticizers used is preferably from 1 to 20% by mass, particularly preferably from 3 to 13% by mass, based on the cellulose ester, in terms of film performance, processability and the like.

(UV absorber)
The ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, More preferably, it is 2% or less.

  The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, and the like. . It is good also as a polymer type ultraviolet absorber.

(Fine particles)
It is preferable to use fine particles in the cellulose ester film according to the present invention. As the fine particles, both inorganic compounds and organic compounds can be used. Examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate And calcium phosphate. Fine particles containing silicon are preferable from the viewpoint of reducing turbidity, and silicon dioxide is particularly preferable.

  The average primary particle size of the fine particles is preferably 5 to 50 nm, and more preferably 7 to 20 nm. These are preferably contained mainly as secondary aggregates having a particle size of 0.05 to 0.3 μm. The content of these fine particles in the cellulose ester film is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.5% by mass. In the case of a cellulose ester film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.). I can do it.

  Zirconium oxide fine particles are commercially available under the trade names of Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of the polymer include silicone resin, fluorine resin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the turbidity of the cellulose ester film low.

(Middle layer)
As the intermediate layer according to the present invention, a urethane acrylate oligomer or a cured product of an acrylate oligomer blocks an eluate from the resin film, and is preferable for obtaining good adhesion to the rod-like polymerizable liquid crystal layer.

(Urethane acrylate oligomer)
The urethane acrylate oligomer used in the present invention is not particularly limited, but is preferably a urethane (meth) acrylate oligomer described in detail below, and the urethane (meth) acrylate oligomer is a (meth) acrylic type. It is obtained by reacting a polyol containing at least one polyol, a polyisocyanate, and a hydroxyl group-containing (meth) acrylate.

  In such a (meth) acrylic polyol, the (meth) acrylic acid alkyl ester constituting the (meth) acrylic polyol includes methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl ( In addition to (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, and other known (meth) acrylic acid alkyl esters. 1 type or 2 types or more are used.

  The method for producing such a (meth) acrylic polyol is not particularly limited. For example, (1) in the presence of a mercaptan (for example, mercaptoethanol, dodecanethiol, etc.) as a chain polymerization agent, the above (meth) acrylic is used. The acid alkyl ester (b1) is radically polymerized to obtain a one-terminal hydroxyl group-containing acrylic polymer or copolymer, and further a short-chain diol (for example, 1,4-butanediol, 3-methyl-1,5-pentanediol) , 1,6-hexanediol, propylene glycol, ethylene glycol, etc.), and the other one-terminal ester group is replaced with a hydroxyl group, (2) an organic halide having two or more starting points, or a sulfonyl halide compound Is used as an initiator to convert the alkyl (meth) acrylate (b1) A method in which a hydroxyl group-containing (meth) acrylate is bonded to both ends of a polymer or copolymer obtained by cal polymerization (both ends are hydroxyl groups based on a hydroxyl group-containing (meth) acrylate), and (3) a hydroxyl group-containing organic halogen. Living radical polymerization of the above (meth) acrylic acid alkyl ester (b1) using a compound as an initiator, and bonding a hydroxyl group-containing (meth) acrylate to the resulting polymer or copolymer (one end is an initiator) And the other end is a hydroxyl group based on a hydroxyl group-containing (meth) acrylate).

  Among these, “TEGO Diol BD 1000”, “TEGO Diol MD 1000N”, “TEGO Diol MD 1000X”, etc. manufactured by Tego Chemie Service are easily available as products manufactured by the method of (1) above.

  Furthermore, the type of the component other than the (meth) acrylic polyol in the polyol is not particularly limited, and examples thereof include a polyether polyol, a polyester polyol, a polycarbonate polyol, a polybutadiene polyol, and a polyolefin polyol.

  The weight average molecular weight of the polyol containing at least one (meth) acrylic polyol is preferably 500 or more, more preferably 600 to 5000, and particularly preferably 750 to 2500. If the molecular weight of the polyol is less than 500, the compatibility is poor.

  The polyisocyanate is not particularly limited, and examples thereof include aromatic, aliphatic, and alicyclic polyisocyanates, among which tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and modified diphenylmethane. Diisocyanate, hydrogenated xylylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4- Diisocyanates such as tetramethylene diisocyanate and naphthalene diisocyanate or trimers thereof are preferred. It is needed. The molecular weight of the polyisocyanate compound is preferably 150 to 700 from the viewpoint of reactivity with a hydroxyl group.

  The hydroxyl group-containing (meth) acrylate is not particularly limited, and examples thereof include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxyethylacryloyl. Phosphate, 4-hydroxybutyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, glycerol di (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl (meth) acrylate, caprolactone Modified 2-hydroxyethyl (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, caprolactone modified 2-hydroxyethyl (meth) acrylate Chromatography, tri propylene glycol (meth) acrylate, 2-hydroxy-3-chloropropyl (meth) acrylate, glycerol mono (meth) acrylate, glycerol methacrylate acrylate.

  Regarding the method for producing a urethane (meth) acrylate oligomer, from the viewpoint of stability of reaction control and shortening of production time, a polyol and a polyisocyanate are reacted to obtain a terminal isocyanate group-containing compound, and then the terminal isocyanate group. A method of reacting the containing compound with a hydroxyl group-containing (meth) acrylate is preferably used.

  In the above method, after reacting polyol and polyisocyanate at a reaction molar ratio of k: k + 1 (molar ratio) (k is an integer of 1 or more), the terminal isocyanate group-containing compound further contains a hydroxyl group ( It is preferred to react the meth) acrylate at a reaction molar ratio of 1: 2.

  In these reactions, it is also preferable to use a catalyst such as dibutyltin dilaurate for the purpose of promoting the reaction.

  In the urethane (meth) acrylate oligomer, the (meth) acrylic polyol is preferably reacted in an amount of 20% by mass or more based on the total of the polyol, the polyisocyanate, and the hydroxyl group-containing (meth) acrylate, particularly 30 to 80. A mass%, and further 40 to 70 mass% is preferable. If the ratio is less than 20% by mass, the compatibility with the acrylic resin tends to be poor, which is not preferable.

(Acrylate oligomer)
Specific examples of the acrylate oligomer include the following, but are not limited to these compounds.

MW number of functional groups (p) MW / p
BASF made: Laromer LR8981 1300 3 433
BASF made: Laromer LR8985 1700 1.5 1133
Others: BASF: Laromer LR8800, PO84F, PO94F, etc. (formation of intermediate layer)
The intermediate layer composition forming the intermediate layer preferably contains the urethane acrylate oligomer or acrylate oligomer, a photopolymerization initiator, and a solvent as main components.

  As the photopolymerization initiator used in the intermediate layer, a general polymerization initiator can be used.

  Specific examples of the photopolymerization initiator include benzoin and derivatives thereof, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and the like. You may use with a photosensitizer. The photopolymerization initiator can also be used as a photosensitizer. In addition, when using an epoxy acrylate photopolymerization initiator, a sensitizer such as n-butylamine, triethylamine, tri-n-butylphosphine can be used. It is preferable to contain 0.1-10 mass% of polymerization initiators with respect to a urethane acrylate oligomer or an acrylate oligomer, More preferably, it is 1-7 mass%.

  The solvent is not particularly limited, but specifically, it is preferable to apply a composition containing a solvent for dissolving the cellulose ester or a solvent for swelling. As a solvent to be used, it is also preferable to include a solvent to be dissolved in addition to a solvent to be dissolved and / or a mixture of solvents to be swollen, and they can be mixed at an appropriate ratio.

  Examples of the solvent for dissolving or swelling the cellulose ester include dioxane, acetone, methyl ethyl ketone, N, N-dimethylformamide, methyl acetate, ethyl acetate, trichloroethylene, methylene chloride, ethylene chloride, tetrachloroethane, trichloroethane, chloroform, propylene glycol monomethyl. Examples include ether and propylene glycol monomethyl ether acetate. Examples of the solvent that does not dissolve include methanol, ethanol, n-propyl alcohol, i-propyl alcohol, n-butanol, cyclohexanol, and hydrocarbons (toluene, xylene).

  Apply these coating compositions to the surface of the transparent support with a dry film thickness of 0.1 to 10 μm using a gravure coater, dip coater, reverse coater, wire bar coater, die coater, spray coating, ink jet coating or the like. It is more preferable to apply at 0.3 to 5 μm, and particularly preferable to apply at 0.3 to 3 μm. If it is this range, it will prevent that the cellulose ester or additive from a transparent support body elutes to a phase difference layer, and raise | generates an orientation inhibition, and is preferable from a viewpoint of productivity and thin film formation.

  10-150 degreeC is preferable and, as for the drying temperature after intermediate | middle layer application | coating, More preferably, it is 40-120 degreeC. The means for drying is not particularly limited and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but is preferably performed with hot air from the viewpoint of simplicity.

  If the temperature is too low, drying takes time and productivity is lowered. If it is too high, film thickness unevenness is likely to occur. If film thickness unevenness occurs in the intermediate layer, film thickness unevenness is likely to occur in the retardation layer. The film thickness unevenness of the retardation layer becomes retardation unevenness as it is, which is not preferable because the display performance of the panel is deteriorated. The drying time is preferably 5 to 600 seconds, more preferably 5 to 200 seconds, still more preferably 5 to 60 seconds. If it is the said range, drying will fully be performed and productivity will be high. In the case of drying with hot air, the wind is preferably weak. When the wind is strong, film thickness unevenness may occur.

As a light source for curing the intermediate layer forming composition by a photocuring reaction to form a cured film layer, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 30 to 300 mJ / cm ² .

The intermediate layer is preferably irradiated with ultraviolet rays during or after coating and drying, and the irradiation time for obtaining the necessary actinic radiation dose is preferably about 0.1 second to 1 minute, and the ultraviolet curable resin is cured. From the viewpoint of efficiency or work efficiency, 0.1 to 10 seconds is more preferable. The illuminance of these active ray irradiators is preferably 50 to 150 mW / m ² .

  Moreover, when irradiating an ultraviolet-ray, it is preferable to apply | coat tension | tensile_strength in the conveyance direction of a film, and the tension | tensile_strength to provide is preferable 30-300 N / m. The method for applying tension is not particularly limited, and tension may be applied in the transport direction on the back roll.

  In the method for producing an optical compensation film of the present invention, it is preferable that the intermediate layer composition is applied, dried, and irradiated with ultraviolet rays to form an intermediate layer, and a retardation layer is formed thereon.

(Polarizer)
The polarizing plate can be produced by a general method. A completely saponified polyvinyl alcohol aqueous solution is applied to at least one surface of a polarizing film prepared by subjecting the back side of the optical compensation film produced by the method for producing an optical compensation film of the present invention to alkali saponification treatment and immersion drawing in an iodine solution. It is preferable to use and bond together. The film may be used on the other surface, or another polarizing plate protective film may be used. Commercially available cellulose ester films (for example, Konica Minoltack KC8UX2M, KC4UX2M, KC5UN, KC4UY, KC8UY, KC12UR, KC4UEW, KC8UCR3, KC8UCR4, KC8UCR5, KC4FR-8, KC4FR-8, KC4FR-8, (Made by Co., Ltd.) is also preferably used.

  The polarizing film, which is the main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound.

(Display device)
By incorporating the polarizing plate into a liquid crystal display device, the liquid crystal display device of the present invention having excellent visibility can be manufactured. The polarizing plate using the optically anisotropic film produced by the method for producing the optical compensation film of the present invention has the optimum viewing angle characteristics of the liquid crystal display device adopting various driving methods such as TN, VA, OCB, HAN, IPS, etc. Can be

  In particular, it is preferably used in VA mode type and IPS mode type LCDs. The liquid crystal display device incorporating the polarizing plate of the present invention has a high contrast even in a large-screen liquid crystal display device having a screen of 30 or more types, particularly 30 to 54 types, and suppresses color change due to viewing angle, for a long time. There is an effect that the eyes are not tired even when watching.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
(Examples 1-11 and Comparative Examples 1-7)
<< Preparation of base film for optical compensation film >>
(Silicon dioxide dispersion)
Aerosil 972V (manufactured by Nippon Aerosil Co., Ltd.) 12 parts by mass (average diameter of primary particles 16 nm, apparent specific gravity 90 g / liter)
88 parts by mass of ethanol or more was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. The liquid turbidity after dispersion was 200 ppm. 88 parts by mass of methylene chloride was added to this silicon dioxide dispersion with stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a silicon dioxide dispersion dilution.

<Aromatic terminal ester 1>
Into a reaction vessel, 820 parts (5 moles) of phthalic acid, 608 parts (8 moles) of 1,2-propylene glycol, 610 parts (5 moles) of benzoic acid and 0.30 parts of tetraisopropyl titanate as a catalyst are charged all at once. While stirring in an air stream, a reflux condenser was attached to reflux excess monohydric alcohol, and heating was continued at 130 to 250 ° C. until the acid value became 2 or less, and water produced was continuously removed. Next, the distillate is removed under reduced pressure of 6.65 × 10 ³ Pa to 4 × 10 ² Pa or less at 200 to 230 ° C., and then filtered to obtain an aromatic terminal ester 1 having the following properties. Obtained.

Viscosity (25 ° C., mPa · s); 19815
Acid value: 0.4
The acid value refers to the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxyl group present at the molecular terminal) contained in 1 g of the sample. The acid value and the hydroxyl value are measured according to JIS K0070.

(Dope solution)
Cellulose ester (acetyl group substitution degree 1.80, propionyl group substitution degree 0.70, total acyl group substitution degree 2.50) 100 parts by mass Trimethylolpropane tribenzoate 5 parts by mass The above aromatic terminal ester 1 5 parts by mass Silicon dioxide Dispersion diluent 10 parts by mass Methylene chloride 430 parts by mass Ethanol 40 parts by mass The above dope composition was put into a sealed container, heated to 70 ° C., and stirred to completely dissolve the cellulose ester to obtain a dope solution. Next, after the dope solution was filtered, the dope solution whose temperature was adjusted to 33 ° C. was fed to the die and uniformly cast with a width of 2.5 m from the die slit onto the stainless steel belt. The cast part of the stainless steel belt was heated from the back with hot water of 37 ° C. After casting, the dope film on the metal support (which is called a web after casting on the stainless steel belt) is dried by applying hot air of 44 ° C., and the residual solvent in the peeling is peeled off at 120 mass%. Then, the web was stretched to a longitudinal stretching ratio of 1.01 times by applying a tension of, and then the end of the web was held with a tenter at a residual solvent amount of 24% and a temperature of 135 ° C., and 1.30 times in the width direction. It extended | stretched so that it might become the draw ratio of. After stretching, the film was held for several seconds while maintaining its width, then the tension in the width direction was relaxed, and the film was dried at 120 ° C. after releasing the width. A cellulose ester film having a thickness of 60 μm, a width of 2.5 m, and a length of 5000 m produced as described above was wound around a core.

  As for the retardation of this cellulose ester film, Ro was 70 nm, Rt was 200 nm, and Rt / Ro was 2.86.

<Coating of retardation layer>
Next, the following polymerizable liquid crystal composition is applied on the obtained cellulose ester film using the optical compensation film manufacturing apparatus 10 of FIG. 1 according to the method of manufacturing an optical compensation film of the present invention to form a retardation layer. An optical compensation film was prepared.

<Preparation and coating of polymerizable liquid crystal composition>
45% by mass of the compound of the following formula (a),

  45% by mass of the compound of the following formula (b),

  10% by mass of the compound of the following formula (c),

A polymerizable liquid crystal composition comprising: The nematic-isotropic liquid phase transition temperature of this polymerizable liquid crystal composition was 73 ° C. Photopolymerization initiator Lucillin TPO (manufactured by BASF Corporation) 0.2 mass% and hindered amine LS-765 (manufactured by Sankyo Lifetech Co., Ltd.) 0.1 mass% were added to 99.7 mass% of the above polymerizable liquid crystal composition to polymerize. Liquid crystalline composition was prepared. Next, a xylene solution containing 33% by mass of a polymerizable liquid crystal composition was prepared. This xylene solution was coated on the cellulose ester film using the coating head 302 of the manufacturing apparatus 10 of FIG. The ambient temperature at the time of application was 20 ° C. After coating, the temperature of the coating film surface in the drying step 4 (three points of the inlet portion, the central portion, and the outlet portion of the drying step 4 was measured with a non-contact thermometer (Keyence Co., IT2-80), and the average value was calculated. The ratio of the solid content immediately after the drying step (calculated from the mass before and after removing the solvent with a vacuum dryer after sampling the film immediately after the drying step), the coating film in the heat treatment step Surface temperature (Three points of the inlet part, the central part, and the outlet part of the heat treatment step 8 were measured with a non-contact thermometer (Keyence Corporation, IT2-80), and the average value was taken as the temperature of the coating film surface.) The heat treatment time and the relative velocity of the gas at a position of 5 mm on the surface of the coating film in the heat treatment step 8 were set as shown in Table 1. After the cooling step, the temperature of the coating film surface immediately before the actinic radiation irradiation step was set to 20 ° C. In this way, the optical compensation film No. 1-18 were produced and it was set as Examples 1-11 and Comparative Examples 1-7. Thereafter, in the actinic radiation irradiation step 7, the polymerizable liquid crystal composition was cured by irradiating with an ultraviolet ray of 250 mJ / mm for 80 seconds at an oxygen concentration of 0.2 vol% and an ambient temperature of 38 ° C. A retardation layer was obtained. For the film thickness measurement, an optical interference film thickness meter FE-3000 (manufactured by Otsuka Electronics Co., Ltd.) was used.

  When the obtained optical compensation film coated with the retardation layer was evaluated using a polarizing microscope, it appeared black when sandwiched between the crossed Nicol polarizers, and the optical compensation film between the crossed Nicol polarizers When tilted, white was observed. Therefore, it was confirmed that the retardation layer was vertically aligned.

<Evaluation of orientation defects>
The optical compensation films prepared in Examples 1 to 11 and Comparative Examples 1 to 7 were observed under a polarizing microscope, the alignment state and alignment defects were evaluated, and the number of alignment defects generated in the retardation layer was measured with an optical microscope. As a result of observation and investigation, the number of point defects (average value in the range of 1.0 mm ² ) was counted.

◎◎◎: 0 to 1 ◎◎: 2 to 3 ◎: 4 to 5 ○: 6 to 10 ×: 11 or more The above evaluation results are shown in Table 1.
(Example 12)
In the production of the optical compensation film of Example 2, before coating the retardation layer, the following intermediate layer was applied to prepare an optical compensation film (No. 19) having an intermediate layer, and Example 12 was obtained. .

《Coating intermediate layer》
<Preparation of composition for intermediate layer>
Purple light UV-7605B (manufactured by Nippon Synthetic Chemical) 25 parts by weight Photopolymerization initiator (1-hydroxy-cyclohexyl-phenylketone) (Irgacure 184, manufactured by Ciba Japan) 1.25 parts by weight Solvent (PGME / isopropyl alcohol mixed solvent ( (Mass ratio 20/80))
75 parts by mass <Coating of intermediate layer>
The intermediate layer composition was applied onto the produced resin film with a slit die and dried at a hot air temperature of 80 ° C. and a drying time of 30 seconds. Subsequently, ultraviolet rays were irradiated with an integrated light quantity of 100 mJ with an irradiation intensity of 150 mW / cm ² with a high-pressure mercury lamp in an atmosphere with an oxygen concentration of 0.5%, and an intermediate layer having a dry film thickness of 1 μm was provided.

  The produced optical compensation film was evaluated for orientation defects in the same manner as in Example 2. The evaluation results are shown in Table 1.

From the results shown in Table 1, when Examples 1 to 5 and Comparative Examples 1 to 7 are compared, the temperature of the coating film is 10 to 40 ° C., and the residual solvent ratio of the coating film after the drying process is 3 Aligned by performing a heat treatment step of heating at a film surface temperature of the coating film for 5 to 15 seconds at a phase transition temperature (73 ° C.) or higher of the polymerizable liquid crystal compound after the drying step. It can be seen that a good optical compensation film can be produced with few defects. Further, when Examples 2 and 6 and 7 are compared, it is found that it is preferable that the temperature of the coating film surface in the heat treatment step is not less than the phase transition temperature and not more than 120 ° C., since there are fewer alignment defects. In addition, when Examples 8 to 11 are compared, the gas at a position of 5 mm on the coating film surface in the heat treatment step moves at a relative speed of 1 to 3 m / sec with respect to the resin film so that there are fewer alignment defects. It turns out that it is preferable. Further, comparing Example 2 and Example 12, it can be seen that it is preferable to provide an intermediate layer on the resin film and apply a retardation layer thereon to reduce alignment defects.
(Examples 13-24, Comparative Examples 8-14)
<Production of polarizing plate>
No. 1 produced in Examples 1-12 and Comparative Examples 1-7. The optical compensation films 1 to 19 were alkali-treated with a 2.5 mol / L aqueous sodium hydroxide solution at 40 ° C. for 60 seconds, washed with water for 3 minutes and saponified to obtain an alkali-treated film.

  Next, a 120 μm-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizing film.

  Next, the polarizing film thus prepared, and Konica Minolta-Tac, KC4UY (manufactured by Konica Minolta Opto Co., Ltd.), which are commercially available polarizing plate protective films, are saponified by the above-mentioned method, and a completely saponified polyvinyl alcohol 5 mass% aqueous solution is obtained. As the pressure-sensitive adhesive, an optical compensation film, a polarizing film, and KC4UY were laminated in this order to produce a viewing-side polarizing plate.

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

  The polarizing plate on the viewing side of the Hitachi liquid crystal television Woo W17-LC50 manufactured by Hitachi, which is an IPS mode type liquid crystal display device, is peeled off, and the polarizing plate produced as described above is aligned with the absorption axis of the polarizing plate in a liquid crystal cell. The IPS mode type liquid crystal display device was produced by pasting on the glass surface. In that case, it bonded so that the optical compensation film of a polarizing plate might become a liquid crystal cell side, and it was set as the liquid crystal display panel of Examples 13-24 and Comparative Examples 8-17.

<Evaluation of liquid crystal display device>
<Evaluation of front contrast of liquid crystal display device>
For evaluation of the front contrast, EZ-contrast manufactured by ELDIM was used, and the amount of transmitted light during black display and white display in the normal direction of the film surface was measured. The front contrast was evaluated by calculating the front contrast = (transmitted light amount when displaying white) / (transmitted light amount when displaying black). A sample having a contrast of 1000 or more was evaluated as “◯” and evaluated as having no practical problem.

<Color shift evaluation>
The change in color when the viewing direction was changed visually was evaluated as a color shift.

A: No color shift is observed. O: A color shift is observed only partially. X: A color shift is clearly observed partially or entirely. Table 2 shows the results obtained.

  From the results of Table 2, when Examples 13 to 24 and Comparative Examples 8 to 14 are compared, by using the method for producing an optical compensation film of the present invention, good display characteristics with good contrast and little color shift are shown. It can be seen that this is a method for producing an optical compensation film with few orientation defects.

DESCRIPTION OF SYMBOLS 1a, 1b Liquid crystal display device 101, 101 'Liquid crystal cell 101a, 101'a, 101b, 101'b Glass substrate 101c, 101'c Liquid crystal layer 102, 102' Viewing side polarizing plate 102a, 103'b 1st protective film 102b, 103′a second protective film 102c, 103′c retardation layer 102d, 103′d first polarizing film 103, 103 ′ backlight side polarizing plate 103a, 102′b third protective film 103b, 102 'A 4th protective film 103c, 102'c 2nd polarizing film 10 Manufacturing apparatus 2 Supply process 201 Resin film 202 Roll-shaped resin film 3 Application | coating process 301 Backup roll 302 Coating head 303 Decompression chamber 304 Coating apparatus 4 Drying process 401 401a Drying device 402 Inlet 403 Exhaust air Flow 5 cooling step 501 the cooling device 502 inlet 503 outlet 6 recovery step 601 rolled resin film 7 active radiation irradiation step 701 the active radiation irradiation device

Claims (6)

Applying a coating solution prepared by dissolving a rod-like polymerizable liquid crystal compound in an organic solvent on a resin film to form a coating film, a drying process for drying the resin film on which the coating film is formed, and the drying In the method for producing an optical compensation film having an active radiation irradiation step of irradiating active radiation to the resin film after the step,
The drying step is a step of setting the temperature of the film surface of the coating film to 10 to 40 ° C. so that the residual solvent ratio of the coating film after the drying step is 3 to 15% by mass,
After the drying step, there is a heat treatment step of heating the film surface temperature of the coating film at a temperature higher than or equal to the phase transition temperature of the polymerizable liquid crystal compound for 5 to 15 seconds,
The actinic radiation irradiation step includes
A method for producing an optical compensation film, wherein after the heat treatment step, the film is irradiated with actinic radiation at a temperature of the coating film surface lower than the phase transition temperature. 2. The method for producing an optical compensation film according to claim 1, wherein in the heat treatment step, a temperature of a film surface of the coating film is not less than the phase transition temperature and not more than 120 ° C. 3. In the heat treatment step, the gas at a position of 5 mm on the surface of the coating film moves in a direction parallel to the surface of the resin film at a relative speed of 1 to 3 m / sec with respect to the resin film. The method for producing an optical compensation film according to claim 1 or 2. 4. The method for producing an optical compensation film according to claim 1, wherein in the heat treatment step, the means for heating the film surface of the coating film is an infrared heater. 5. The method for producing an optical compensation film according to claim 1, wherein the resin film is a cellulose ester film. The intermediate layer for suppressing that the constituent material of the said resin film oozes out into the said coating film on the surface of the said resin film is formed in any one of Claim 1 to 5 characterized by the above-mentioned. The manufacturing method of the optical compensation film of description.

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