JP4981269B2 - Laminated optical compensation film, composite polarizing plate, and liquid crystal display element - Google Patents

Description

The present invention relates to a laminated optical compensation film, a composite polarizing plate, a liquid crystal display element, and a liquid crystal alignment film used for improving the image quality of a liquid crystal display device.

Liquid crystal display devices are used for notebook personal computers, personal computer monitors, and the like, but in recent years, they have also been used for large-sized televisions, and the demand is rapidly increasing.
Along with this, various optical compensation films have been proposed to perform optical compensation of liquid crystal display devices.

The optical compensation film is roughly classified into a stretched optical compensation film obtained by stretching a polymer film uniaxially or biaxially, and a liquid crystal layer laminated film in which a liquid crystal layer is laminated on a substrate such as a polymer film.
Since the type of liquid crystal used can achieve various compensation forms by controlling the alignment state and can be made thinner than a stretched optical compensation film, a liquid crystal layer laminated film is useful. For example, Patent Document 1 discloses a method for producing the same. Has been.

As a material for the film layer of the liquid crystal laminated type optical compensation film, triacetyl cellulose is used because of its transparency and low residual retardation.
However, the liquid crystal display device manufactured using such an optical compensation film having a film layer made of triacetyl cellulose is heated in the film layer of the optical compensation film due to heat generated by the backlight during use. There has been a problem that display failure, which is called light loss due to stress, occurs.

In response to such problems, in recent years, cycloolefin resins having excellent heat resistance and a small photoelastic coefficient are being used instead of triacetyl cellulose as a material for the film layer. However, it is difficult to apply a liquid crystal solution on a cycloolefin-based resin film to form a liquid crystal layer, which causes repelling, and the cycloolefin resin film and the liquid crystal layer have poor adhesion. There was a problem.
In addition, the cycloolefin resin film does not sufficiently align even if it is rubbed to align liquid crystal molecules, so an alignment film is required to laminate the liquid crystal layer on the cycloolefin resin film, and the manufacturing process There was also a problem that became complicated.
JP 2004-317651 A

An object of this invention is to provide the laminated optical compensation film used for the improvement of the image quality of a liquid crystal display device, a composite polarizing plate, a liquid crystal display element, and the liquid crystal aligning film in view of the said present condition.

The present invention is a laminated optical compensation film comprising a cycloolefin resin film and a liquid crystal layer laminated on the cycloolefin resin film, the cycloolefin resin film on the side in contact with the liquid crystal layer The laminated optical compensation film has a surface subjected to a normal pressure plasma treatment with an inert gas having an oxygen concentration of 15% by volume or less and a rubbing treatment subsequent to the normal pressure plasma treatment.
The present invention is described in detail below.

As a result of intensive studies, the inventors have performed a normal pressure plasma treatment on the surface of the cycloolefin-based resin film under specific conditions, thereby providing a coating property of the liquid crystal solution on the cycloolefin-based resin film, and a cycloolefin-based film. The adhesion between the resin film and the liquid crystal layer is improved, and the liquid crystal can be aligned without using a separate alignment film by applying a rubbing treatment from above the cycloolefin resin film that has been subjected to atmospheric pressure plasma treatment. In addition, the inventors have found that the effects of atmospheric pressure plasma treatment are not lost, and have completed the present invention.

The laminated optical compensation film of the present invention comprises a cycloolefin resin film and a liquid crystal layer laminated on the cycloolefin resin film.

The cycloolefin-based resin film is formed by forming a cycloolefin-based resin.
The cycloolefin-based resin is not particularly limited, and examples thereof include norbornene-based resins and dicyclopentadiene-based resins. Among these, those having no unsaturated bond or having an unsaturated bond hydrogenated are preferably used. For example, a ring-opening (co) polymer of one or more norbornene monomers is used. Hydrogenated products, addition (co) polymers of one or more norbornene monomers, addition copolymers of norbornene monomers and olefin monomers (ethylene, α-olefin, etc.), norbornene monomers and cycloolefins And addition copolymers with a series monomer (cyclopentene, cyclooctene, 5,6-dihydrodicyclopentadiene, etc.), and modified products thereof, specifically, ZEONEX, ZEONOR (manufactured by Nippon Zeon Co., Ltd.) , ARTON (manufactured by JSR), TOPAS (manufactured by Chicona), APL (manufactured by Mitsui Chemicals) and the like.

The film forming method is not particularly limited, and a conventionally known film forming method may be used. Specifically, for example, a cycloolefin-based resin is supplied to an extruder and melted and kneaded. A method of forming a long cycloolefin resin film by extrusion from a mold attached to a film (melt extrusion method), a solution obtained by dissolving a cycloolefin resin in an organic solvent on a drum or band And a method of evaporating the organic solvent and then forming a long cycloolefin resin film (solution casting method).
In addition, when the thickness of the cycloolefin-based resin film is 80 μm or more, it may be difficult to sufficiently evaporate and remove the organic solvent by the solution casting method. Therefore, it is preferable to use the melt extrusion method. .

In the laminated optical compensation film of the present invention, the cycloolefin-based resin film has a normal pressure plasma treatment with an inert gas having an oxygen concentration of 15% by volume or less on the surface in contact with the liquid crystal layer, and the normal pressure. A rubbing process is performed following the plasma process.
The surface of the cycloolefin resin film is subjected to atmospheric pressure plasma treatment with an inert gas having an oxygen concentration of 15% by volume or less, and the surface of the cycloolefin resin film has an oxygen concentration of A film for aligning liquid crystal, which is subjected to atmospheric pressure plasma treatment with an inert gas of 15% by volume or less and subsequently subjected to rubbing treatment, is also one aspect of the present invention.

In the normal pressure plasma treatment, a voltage is applied to a gas introduced between electrodes to excite the gas into a plasma gas, and the surface of the object to be processed is hydrophilized with the plasma gas.

The atmospheric pressure plasma treatment is preferably performed in an apparatus having a pair of counter electrodes, and a solid dielectric is installed on at least one of the counter surfaces of the electrodes. When the solid dielectric is installed on one of the electrodes, the plasma is generated between the solid dielectric and the electrode. When the solid dielectric is installed on both of the electrodes, the plasma is generated between the solid dielectrics. Space. A normal pressure plasma treatment is performed by disposing a hydrophobic resin film as a target object of the hydrophilization treatment between the solid dielectric and the electrode or between the solid dielectrics.

The electrode is not particularly limited, and examples thereof include those made of simple metals such as copper and aluminum, alloys such as stainless steel and brass, and metal compounds.

The counter electrode preferably has a structure in which the distance between the counter electrodes is substantially constant in order to avoid occurrence of arc discharge due to electric field concentration. Examples of the electrode structure that satisfies this condition include a parallel plate type, a cylindrical opposed flat plate type, a spherical opposed flat plate type, a hyperboloid, an opposed flat plate type, and a coaxial cylindrical type structure.

The solid dielectric is preferably disposed on one or both of the opposing surfaces of the electrode. At this time, the solid dielectric and the electrode on the side to be installed are in close contact with each other, and the opposing surface of the electrode in contact is completely covered. This is because if there is a portion where the electrodes directly face each other without being covered by the solid dielectric, arc discharge occurs from there.
The solid dielectric may be in the form of a sheet or a film, but the lower limit of the preferred thickness is 0.01 mm, and the upper limit of the preferred thickness is 4 mm. If it is less than 0.01 mm, a high voltage is required to generate discharge plasma, and if it exceeds 4 mm, dielectric breakdown occurs when voltage is applied and arc discharge occurs.

The material of the solid dielectric is not particularly limited, and examples thereof include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxides such as silicon dioxide, aluminum oxide, zirconium dioxide, and titanium dioxide, and barium titanate. Examples include double oxides.
The solid dielectric preferably has a relative dielectric constant of 2 or more in a 25 ° C. environment. Specific examples of the dielectric having a relative dielectric constant of 2 or more include, for example, polytetrafluoroethylene, glass, and metal oxide film. Further, in order to stably generate a high density discharge plasma, it is preferable to use a solid dielectric having a relative dielectric constant of 10 or more.
The upper limit of the relative dielectric constant is not particularly limited, but an actual material of about 18500 is known. The solid dielectric having a relative dielectric constant of 10 or more is composed of a metal oxide film mixed with 5 to 50% by weight of titanium oxide and 50 to 95% by weight of aluminum oxide, or a metal oxide film containing zirconium oxide. It is preferable to use a film having a thickness of 10 to 1000 μm.

The distance between the electrodes is not particularly limited and is determined in consideration of the pressure of the atmospheric gas, the oxygen concentration, the thickness of the solid dielectric, the magnitude of the applied voltage, the purpose of using the film subjected to plasma discharge treatment, and the like. The preferred lower limit is 0.5 mm, and the preferred upper limit is 50 mm. If the thickness is less than 0.5 mm, the variation in the atmospheric gas concentration between the electrodes is large, the processing is likely to be non-uniform, and the thickness of the workpiece to be installed between the electrodes is limited. If it exceeds 50 mm, it is difficult to generate uniform discharge plasma.
The applied voltage is preferably a pulse voltage. The pulse waveform may be any of an impulse type, a square wave type, and a modulation type waveform. Furthermore, even if the applied voltage is positive and negative, a single-wave shape waveform in which voltage is applied to either the positive or negative polarity side. It may be.

The voltage rise time of the pulse voltage is not particularly limited, but a preferable lower limit is 40 ns, and a preferable upper limit is 100 μs. Here, the voltage rise time of the pulse voltage means a time during which the voltage change is continuously positive. It is difficult to realize a pulse voltage having a voltage rise time of less than 40 ns. If the pulse voltage exceeds 100 μs, the discharge state tends to shift to an arc and becomes unstable, and a high-density plasma state due to the pulse voltage cannot be expected. A more preferable lower limit is 50 ns, and a more preferable upper limit is 5 μs.
Further, the voltage fall time of the pulse voltage is preferably steep, and the time scale is preferably 100 μs or less, which is the same as the voltage rise time of the pulse voltage. For example, in the power supply device used in the embodiments of the present invention, the voltage rise time and the voltage fall time of the pulse voltage can be set to the same time, although it depends on the pulse electric field generation technique.

Although it does not specifically limit as a frequency of a pulse voltage, A preferable minimum is 0.5 kHz and a preferable upper limit is 100 kHz. If it is less than 0.5 kHz, the plasma density is low, so that the process takes too much time. If it exceeds 100 kHz, arc discharge tends to occur. A more preferred lower limit is 1 kHz.

Although it does not specifically limit as pulse duration in the said pulse voltage, A preferable minimum is 1 microsecond and a preferable upper limit is 1000 microseconds. If it is less than 1 μs, the discharge becomes unstable, and if it exceeds 1000 μs, it tends to shift to arc discharge. A more preferable lower limit is 3 μs, and a more preferable upper limit is 200 μs. Here, the pulse duration means a time for which a pulse continues in a pulse voltage consisting of repetition of ON and OFF.
Furthermore, in order to stabilize the discharge, it is preferable to have an OFF time that lasts at least 1 μs within a discharge time of 1 ms. Further, a direct current may be superimposed when applying a pulse voltage.

The atmospheric gas that generates plasma discharge is a gas containing at least oxygen gas. Nitrogen gas, argon gas, etc. are mentioned as mixed gas other than oxygen gas, The volume ratio of gas other than oxygen gas and oxygen can be mixed by substantially arbitrary ratios in the range of 15:85 to 1:99. . When the oxygen gas concentration in the mixed gas exceeds 15% by volume, the adhesiveness of the polymerizable liquid crystal layer is rapidly lowered. In addition, although the lower limit of the oxygen gas concentration in the mixed gas is not particularly limited, in the present invention, since the treatment is performed near normal pressure, it does not become completely oxygen-free, and substantially no oxygen is present. It only has to exist. A more preferable upper limit of the oxygen gas concentration is 10% by volume.

The pressure of the atmospheric plasma treatment is not particularly limited, but a preferable lower limit is 100 Torr (about 1.33 × 10 ⁴ Pa), a preferable upper limit is 800 Torr (about 10.6 × 10 ⁴ Pa), and a more preferable lower limit is 700 Torr (about 9.31 × 10 ⁴ Pa), and a more preferable upper limit is 780 Torr (about 10.4 × 10 ⁴ Pa).

The rubbing treatment method is not particularly limited, and a conventionally known means can be used. For example, rubbing that can set a length direction on the film while conveying a long film. Examples include a method in which a roll is set, the rubbing roll is rotated and brought into contact with the film surface, and the substrate surface is rubbed. What is necessary is just to set suitably the conveyance speed of a film, a rubbing angle, the rotation speed of a rubbing roll, a rubbing pressure, etc. according to the target rubbing process.
Also, the material of the rubbing material such as the rubbing roll surface material to be used is not particularly limited, but considering that the film obtained by the rubbing treatment is used for optical applications, felts such as nylon, cotton, polyester, etc. It is preferable to select a material that is not easily damaged.
In the laminated optical compensation film of the present invention, the liquid crystal layer can be homogeneously aligned by subjecting the cycloolefin resin film that has been subjected to atmospheric pressure plasma treatment to rubbing treatment.

The liquid crystal layer is not particularly limited as long as it is usually a liquid crystal layer used for a liquid crystal laminated type optical compensation film. However, since there is little damage to the film, a liquid crystal layer having a low temperature is preferable. For this, a liquid crystal layer made of a polymerizable liquid crystal composition is preferably used.

The polymerizable liquid crystal composition is not particularly limited, and examples thereof include those containing at least one polymerizable liquid crystal compound selected from the group consisting of the following formulas (1) to (7).

The above formula (1) can be synthesized by the method described in JP-A-9-316032. The above formula (2) can be synthesized by the method described in JP-A-7-17910. The above formula (3) can be synthesized by the method described in WO98 / 00428. The above formula (4) can be synthesized by the method described in DE19504224. The above formula (5) is obtained from Makromol. Chem. 190, 3201-3215 (1989). The above formula (6) can be synthesized by the method described in JP-A-2003-48903. The above formula (7) can be synthesized by the method described in WO97 / 00600.

The method for producing the laminated optical compensation film of the present invention is not particularly limited. For example, the polymerizable liquid crystal composition used as a raw material for the liquid crystal layer on the cycloolefin resin film that has been subjected to atmospheric pressure plasma treatment as described above. Examples thereof include a method in which a solvent, a polymerization initiator, etc. are added to obtain a liquid crystal solution, which is coated on a cycloolefin resin film and dried.

The solvent is not particularly limited. For example, benzene, toluene, xylene, mesitylene, n-butylbenzene, diethylbenzene, tetralin, methoxybenzene, 1,2-dimethoxybenzene, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, methyl Isobutyl ketone, cyclopentanone, cyclohexanone, ethyl acetate, ethyl lactate, methyl lactate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, γ-butyrolactone, 2-pyrrolidone, N-methyl-2 -Pyrrolidone, dimethylformamide, chloroform, dichloromethane, carbon tetrachloride, dichloroethane , Tetrachlorethylene, trichlorethylene, tetrachlorethylene, chlorobenzene, t- butyl alcohol, diacetone alcohol, glycerin, monoacetin, ethylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl ether, ethyl cellosolve, butyl cellosolve, and the like. The solvent may be a single compound or a mixture.

The ratio of the solvent is not particularly limited, but a preferable lower limit is 60% by weight and a preferable upper limit is 95% by weight based on the total amount of the polymerizable liquid crystal composition. If it is less than 60% by weight, the solubility of the polymerizable liquid crystal composition and the optimum viscosity cannot be obtained when it is applied. If it exceeds 95% by weight, the solvent cost and the time and amount of heat for evaporating the solvent are reduced. It is not preferable from the economical viewpoint. A more preferred lower limit is 50% by weight, a more preferred upper limit is 90% by weight, a further preferred lower limit is 70% by weight, and a still more preferred upper limit is 85% by weight.

In order to optimize the polymerization rate of the polymerizable liquid crystal composition, a known photopolymerization initiator may be added. The addition amount of the photopolymerization initiator is not particularly limited, but based on the total amount of the polymerizable liquid crystal composition, a preferred lower limit is 0.01% by weight, a preferred upper limit is 10% by weight, and a more preferred lower limit is 0. 0.1% by weight, and a more preferable upper limit is 7% by weight.
The photopolymerization initiator is not particularly limited, and examples thereof include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2,2-dimethoxy-1,2-diphenylethane. -1-ON, Irgacure 500, Irgacure 2959, Irgacure 907, Irgacure 369, Irgacure 1300, Irgacure 819, Irgacure 1700, Irgacure 1800, Irgacure 1850, Darocur 4265, Irgacure 784, Irgacure 754, Irgacure OXE01, p-methoxyphenyl-2,4-bis (trichloromethyl) triazine, 2- (p-butoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 9-pheni Acridine, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, benzyldimethyl ketal, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1- ON, and a mixture of 2,4-diethylxanthone and methyl p-dimethylaminobenzoate. Both Darocur and Irgacure are manufactured by Ciba Specialty Chemicals. Known sensitizers (isopropylthioxanthone, diethylthioxanthone, etc.) may be added to these.

Other examples of the photo radical polymerization initiator include p-methoxyphenyl-2,4-bis (trichloromethyl) triazine, 2- (p-butoxystyryl) -5-trichloromethyl-1,3,4-oxa. Diazole, 9-phenylacridine, 9,10-benzphenazine, benzophenone / Michler's ketone mixture, hexaarylbiimidazole / mercaptobenzimidazole mixture, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1- ON, benzyldimethyl ketal, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2,4-diethylxanthone / methyl p-dimethylaminobenzoate, benzophenone / methyltri Ethanolamine mixture etc. That.

The coating method is not particularly limited, and examples thereof include a die coating method, a roll coating method, a gravure coating method, a micro gravure method, a spin coating method, and a bar coating method.

When the liquid crystal solution is applied, the solvent is removed after the application to form a liquid crystal solution layer having a uniform film thickness, that is, a liquid crystal layer, on the cycloolefin-based resin film. The conditions for removing the solvent are not particularly limited, and it may be dried until the solvent is almost removed and the fluidity of the coating film is lost. Air drying at room temperature, drying on a hot plate, drying in a drying oven, hot air or hot air The solvent can be removed by using spraying or the like. Depending on the kind and composition ratio of the polymerizable liquid crystal compound, nematic alignment of the polymerizable liquid crystal composition in the coating film may be completed in the course of drying the coating film. Therefore, the coating film that has undergone the drying process can be subjected to the polymerization process without going through a heat treatment process to be described later. However, in order to make the alignment of the liquid crystal molecules in the coating film more uniform, it is preferable to heat-treat the coating film that has undergone the drying step and then to perform photopolymerization.

The temperature and time when heat-treating the coating film, the wavelength of light used for light irradiation, the amount of light irradiated from the light source, etc. are the type and composition ratio of the polymerizable liquid crystal compound, the presence or absence of addition of a photopolymerization initiator, The preferred range varies depending on the amount added. Accordingly, the conditions regarding the temperature and time of the heat treatment of the coating film described below, the wavelength of the light used for light irradiation, and the amount of light irradiated from the light source are merely an approximate range.

The heat treatment of the coating film is preferably performed under the condition that the solvent is removed and the uniform orientation of the polymerizable liquid crystal is obtained, and may be performed at a temperature higher than the liquid crystal phase transition point of the polymerizable liquid crystal composition. Examples of the heat treatment method include a method of heating the coating film to a temperature at which the polymerizable liquid crystal composition exhibits a nematic liquid crystal phase to form a nematic alignment in the polymerizable liquid crystal composition in the coating film. Nematic alignment may be formed by changing the temperature of the coating film within a temperature range in which the polymerizable liquid crystal composition exhibits a nematic liquid crystal phase. This method is a method in which a nematic orientation is substantially completed in a coating film by heating the coating film to a high temperature range of the above temperature range, and then the order is further ordered by lowering the temperature. In any of the above heat treatment methods, the preferred lower limit of the heat treatment temperature is room temperature, the preferred upper limit is 120 ° C., the more preferred upper limit is 90 ° C., and the still more preferred upper limit is 70 ° C.
The preferable lower limit of the heat treatment time is 5 seconds, the preferable upper limit is 2 hours, the more preferable lower limit is 10 seconds, the more preferable upper limit is 40 minutes, the still more preferable lower limit is 20 seconds, and the further preferable upper limit is 20 minutes. is there. In order to raise the temperature of the layer made of the polymerizable liquid crystal composition to a predetermined temperature, the heat treatment time is preferably 5 seconds or more. In order not to lower the productivity, it is preferable to set the heat treatment time within 2 hours. In this way, the polymerizable liquid crystal layer of the present invention is obtained.

The wavelength of the light used for the light irradiation is not particularly limited, but the preferred lower limit is 150 nm, the preferred upper limit is 500 nm, the more preferred lower limit is 250 nm, the more preferred upper limit is 450 nm, the still more preferred lower limit is 300 nm, and the still more preferred upper limit. Is 400 nm. As said light, an electron beam, an ultraviolet-ray, visible light, infrared rays (heat ray) etc. can be utilized, for example, Usually, an ultraviolet-ray or visible light should just be used. Specific examples of the light source include, for example, a low-pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), a high-pressure discharge lamp (high-pressure mercury lamp, metal halide lamp), a short arc discharge lamp (ultra-high-pressure mercury lamp, xenon lamp, Mercury xenon lamp) and the like. Of these, metal halide lamps, xenon lamps, and high-pressure mercury lamps are preferably used. The wavelength region of the irradiation light source may be selected by installing a filter or the like between the light source and the polymerizable liquid crystal layer and passing only a specific wavelength region. No particular limitation is imposed on the amount of light emitted from the light source, the preferred lower limit is 2 mJ / cm ^2, a preferred upper limit is 5000 mJ / cm ^2, and more preferable lower limit is 10 mJ / cm ^2, and more preferred upper limit is 3000 mJ / cm ^2, A more preferred lower limit is 100 mJ / cm ² , and a more preferred upper limit is 2000 mJ / cm ² . It is preferable that the temperature condition at the time of light irradiation is set similarly to the above heat treatment temperature.

In the laminated optical compensation film of the present invention, the liquid crystal layer preferably has a front retardation of 20 nm or more. If it is less than 20 nm, a sufficient optical compensation effect may not be obtained.

A composite polarizing plate can be produced by laminating the laminated optical compensation film of the present invention on a conventionally known polarizing plate.
A composite polarizing plate in which the laminated optical compensation film of the present invention is laminated on a polarizing plate is also one aspect of the present invention.

A liquid crystal display element using the composite polarizing plate of the present invention is also one aspect of the present invention.

ADVANTAGE OF THE INVENTION According to this invention, the applicability | paintability of the liquid crystal solution which was the problem of the cycloolefin type-resin film can be improved remarkably, and the lamination | stacking optical compensation film excellent in adhesiveness with a liquid crystal layer can be provided. .
Since the laminated optical compensation film of the present invention uses a cycloolefin resin film having excellent transparency and heat resistance and a small photoelastic coefficient, even when heated by the heat generated from the backlight, Display defects do not occur.
According to the present invention, it is possible to provide a laminated optical compensation film, a composite polarizing plate, a liquid crystal display element, and a liquid crystal alignment film used for improving the image quality of a liquid crystal display device.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
(Production of cycloolefin film)
A thermoplastic saturated norbornene resin (trade name “ZEONOR # 1420” manufactured by Nippon Zeon Co., Ltd.) was used as the cycloolefin resin, and this was supplied to a single screw extruder, melted and kneaded, and attached to the tip of the single screw extruder. Melt extrusion was performed from the die to obtain a long film having a width of 650 mm and an average thickness of 65 μm.

(Normal pressure plasma treatment)
FIG. 1 shows a plasma discharge treatment apparatus. In the metal chamber 1, the upper electrode 2 (made of stainless steel (SUS304), size: 150 mm × 100 mm) and the lower electrode 3 (made of stainless steel (SUS304), size: 150 mm × 100 mm) are insulated from the metal chamber 1. It is arranged in the state. The distance between the electrodes is 2 mm. The electrode facing surfaces of the upper electrode 2 and the lower electrode 3 are covered with a sprayed film 4 of Al ₂ O _{3 having} a thickness of 1.5 mm.
After the cycloolefin-based resin film 7 was disposed between the upper electrode 2 and the lower electrode 3, exhaust was performed with an oil rotary pump until the inside of the apparatus became 1 Torr (about 133 Pa). After evacuation, a mixed gas in which nitrogen and oxygen were mixed at a volume ratio of 90:10 was introduced from the gas introduction pipe 5 until the inside of the apparatus reached 760 Torr (about 1.01 × 10 ⁵ Pa).
Plasma discharge is performed by applying an AC pulse voltage between the electrodes from the pulse power source 6 with a rise time of 5 μs, a pulse width of 100 μs, a frequency of 7 kHz, and a voltage of ± 5 kV, and plasma discharge treatment is performed on one side of the cycloolefin resin film 7 Went. The cycloolefin-based resin film 7 was subjected to plasma discharge treatment while moving between the upper electrode 2 and the lower electrode 3 at a speed of 4 m / min.

(Rubbing process)
The surface of the cycloolefin-based resin film treated with atmospheric pressure plasma was rubbed with a nylon felt.

(Synthesis of polymerizable liquid crystal compound (5))
4-Hydroxybenzoate (16.6 g) and sodium hydroxide (4 g) were added to 2-butanone (300 mL), and sodium iodide (15 g) and 6-chlorohexanol (15 g) were further added and heated to 60 ° C. After 10 hours, the solvent was removed, and the residue was washed with aqueous sodium hydroxide solution, added to 0.5 M aqueous potassium hydroxide solution, and refluxed for 5 hours. Then, neutralization and recrystallization were performed, 230 mL of 1,4-dioxane, 13.9 g of N, N-dimethylaniline and 10.4 g of acryloyl chloride were added, and the mixture was heated to 60 ° C. 11.7 g of the material obtained by recrystallization was added to 100 mL of 1,2-dimethoxyethane, 8.1 g of triethylamine, and 4.6 g of sulfonyl chloride, and cooled to -30 ° C. After 1 hour, 2.5 g of 2-methyl-1,4-dihydroxybenzene and 0.5 g of 4- (dimethylamino) pyridine were added and kept at 5 ° C. for 3 hours, whereby a polymerizable liquid crystal represented by the following formula (5) was obtained. A compound was obtained.

(Preparation of polymerizable liquid crystal composition)
The polymerization initiator 2,2-dimethoxy-1,2-diphenylethane-1-one having a weight ratio of 0.03 was added to the polymerizable liquid crystal compound (5). Toluene was added to this composition to prepare a polymerizable liquid crystal composition solution (liquid crystal solution) having a solvent content of 75% by weight.

(Preparation of laminated optical compensation film)
The polymerizable liquid crystal composition solution (liquid crystal solution) was applied by spin coating on the surface-treated surface of the cycloolefin resin film held on a 10 cm × 10 cm glass substrate. After coating, the solvent was dried on a hot plate maintained at 100 ° C. Further, this was cured by irradiating UV with a halogen lamp to produce a laminated optical compensation film having an almost ½ wavelength plate. The integrated irradiation amount was 400 mJ, and the oxygen concentration in the atmosphere was 5%.

(Example 2)
A laminated optical compensation film was produced in the same manner as in Example 1 except that the liquid crystal solution was applied so as to be a quarter wavelength plate.

(Comparative Example 1)
A laminated optical compensation film was produced in the same manner as in Example 1 except that a cycloolefin-based resin film not subjected to atmospheric pressure plasma treatment was used.

(Comparative Example 2)
A laminated optical compensation film was produced in the same manner as in Example 1 except that the rubbing treatment was not performed.

(Comparative Example 3)
A corona discharge treatment device (high frequency power supply device AGI-020) manufactured by Kasuga Denki Co., Ltd. was used instead of the atmospheric pressure plasma treatment, and the corona was applied to one side of the cycloolefin resin film at a treatment strength of 0.2 kW and a speed of 4.0 m / min. A laminated optical compensation film was produced in the same manner as in Example 1 except that the discharge treatment was performed.

<Evaluation>
The following evaluation was performed about the laminated optical compensation film obtained in Examples 1-2 and Comparative Examples 1-3. The results are shown in Table 1.

(Measurement of contact angle)
The contact angle between the cycloolefin resin film and the liquid crystal solution when the liquid crystal solution was applied onto the cycloolefin resin film was measured by G2 manufactured by KRUSS.

(Repel evaluation)
The repellency of the liquid crystal solution with respect to the cycloolefin resin film when the liquid crystal solution was applied onto the cycloolefin resin film was visually observed and evaluated according to the following criteria.
○ Uniform coating was possible without repelling.
Δ: Unevenness occurred due to slight repelling, but coating was possible.
X It was difficult to coat due to repelling.

(Adhesion evaluation)
For the obtained laminated optical compensation film, the adhesion of the liquid crystal layer to the cycloolefin resin film was measured and evaluated by a method according to JIS K 5600-5-6 cross-cut method (1 mm width 100 mass).

(Phase difference measurement)
The obtained laminated optical compensation film was measured using a phase difference measuring device KOBRA-21ADH (manufactured by Oji Scientific Instruments). The slow axis angle was expressed with the rubbing direction as 0 degree.

(appearance)
The obtained laminated optical compensation film was sandwiched between polarizing plates arranged in crossed Nicols and evaluated visually.

According to the present invention, it is possible to provide a laminated optical compensation film, a composite polarizing plate, a liquid crystal display element, and a liquid crystal alignment film used for improving the image quality of a liquid crystal display device.

It is a schematic diagram which shows an example of a plasma discharge processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal chamber 2 Upper electrode 3 Lower electrode 4 Thermal spray film 5 Gas introduction pipe 6 Pulse power supply 7 Cycloolefin resin film

Claims (4)

A laminated optical compensation film comprising a cycloolefin resin film and a liquid crystal layer laminated on the cycloolefin resin film,
The cycloolefin-based resin film is subjected to a normal pressure plasma treatment with an inert gas having an oxygen concentration of 15% by volume or less on the surface in contact with the liquid crystal layer, and a rubbing treatment subsequent to the normal pressure plasma treatment. A laminated optical compensation film characterized by comprising: The laminated optical compensation film according to claim 1, wherein the liquid crystal layer has a front retardation of 20 nm or more. A composite polarizing plate comprising the laminated optical compensation film according to claim 1 or 2 laminated on a polarizing plate. A liquid crystal display element comprising the composite polarizing plate according to claim 3.

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