JP2009128793A - Method for manufacturing tilt-alignment retardation film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a tilt-alignment retardation film substantially preventing alignment failure and having excellent uniformity. <P>SOLUTION: The method for manufacturing a tilt-alignment retardation film includes: a step of applying a liquid crystal composition solution containing one or more polymerizable liquid crystal compounds, a leveling agent and a solvent on a substrate to form a coating layer; and a step of drying the coating layer under the condition of heat quantity Q satisfying 100<Q<300 to form a liquid crystal solidified layer with tilt alignment. An acrylic leveling agent is preferably used for the leveling agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a tilted alignment retardation film that can be preferably used for an image display device, for example, a liquid crystal display device (LCD).

  The retardation film is used as a member that realizes improvement in contrast and enlargement of a viewing angle in an image display device such as a liquid crystal display device by utilizing birefringence. As the retardation film, a film obtained by stretching a polymer film and imparting optical anisotropy is widely used.

  On the other hand, what coated the optically anisotropic layer containing a liquid crystal compound on transparent substrates, such as a polymer film, is also used as retardation film. In particular, since liquid crystal compounds have a large birefringence, the same retardation can be obtained with a small thickness compared to a retardation film obtained by stretching a polymer film. It has been attracting attention with the current trend.

  As a retardation film in which a liquid crystal compound is aligned, a film in which a liquid crystal compound is aligned horizontally (homogeneously) with respect to a substrate is known (see, for example, Patent Document 1). Such a retardation film is widely used as a so-called A plate because the refractive index is different between the alignment direction of the liquid crystal in the film plane and the vertical direction thereof, that is, in-plane birefringence occurs. In addition, a liquid crystal compound in which the liquid crystal compound is aligned perpendicularly (homeotropically) to the base material (for example, Patent Document 2) is also known. Such a retardation film is widely used as a so-called C plate because the refractive index in the film plane is different from that in the film thickness direction, which is the alignment direction of the liquid crystal compound, that is, birefringence in the thickness direction is generated.

  In addition to these, liquid crystal compounds with tilted alignment (for example, Patent Document 3) are also known, and mainly hybrids such as twisted nematic mode (TN) liquid crystal cells and optically compensated bend (OCB) mode liquid crystal cells. It is used for optical compensation of nematic alignment type liquid crystal cells.

JP 2004-347698 A JP 2003-177242 A JP 2007-206241 A

  However, a retardation film in which such a liquid crystal compound is tilted is more likely to cause alignment failure and unevenness in the film than a retardation film in which a liquid crystal compound is horizontally or vertically aligned. There is. In particular, in the production method of the example of Patent Document 3, it has been found that a leveling agent is not used, and the amount of heat at the time of drying is too large, so that orientation failure tends to occur.

  As a result of intensive studies, the inventors of the present application have found that the above-described problems can be solved by adjusting the drying conditions after applying a liquid crystal composition solution containing a leveling agent on a substrate, and have reached the present invention. . That is, the present invention provides a coating step of coating a liquid crystal composition solution containing one or more polymerizable liquid crystal compounds, a leveling agent, and a solvent on a substrate to form a coating layer, and the following formula: It is related with the manufacturing method of the inclination-alignment phase difference film which has the drying process which dries this coating layer on the conditions which become calorie | heat amount Q represented by 100 <Q <300, and forms the liquid crystal solidified layer which carried out the inclination alignment.

However, t is the time (minutes) from the start of drying to the end of drying in the drying step, and T (t) is the ambient temperature (° C.) at time t.

  Furthermore, in the manufacturing method of the inclined orientation retardation film of this invention, it is preferable that the maximum value of temperature T (t) in the said drying process is 60 degreeC or more and 120 degrees C or less.

  Furthermore, in the manufacturing method of the tilt alignment retardation film of this invention, it is preferable that the said leveling agent is an acrylic leveling agent.

  In the method for producing a tilted alignment retardation film of the present invention, the acrylic leveling agent is preferably a compound having a structural unit represented by the following general formula (IV).

(R ₃ is hydrogen or a methyl group, R ₄ is a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched halogenated alkyl group having 1 to 10 carbon atoms, a polyester group, or (It is a polyether group.)

  Furthermore, in the manufacturing method of the tilt alignment retardation film of this invention, it is preferable to contain an acryl-type liquid crystal compound as said polymeric liquid crystal compound.

  In the method for producing a tilted alignment retardation film of the present invention, the acrylic liquid crystal compound is preferably a compound represented by the following general formula (II).

(Y ₁ and Y ₂ are each independently acrylate group, methacrylate group, vinyl group, isopropenyl group, 4-vinylphenyl group, 1-chloroethenyl group, epoxy group, cyanate group, isocyanate group, hydrogen, halogen, alkyl group. , An alkoxy group, a cyano group, or a nitro group, and at least one of Y ₁ and Y ₂ is an acrylate group or a methacrylate group, and X ₁ and X ₂ are each independently a covalent bond, linear or branched An alkylene group, an ether group, a carbonyl group, an ester group, a carbonate group, or a divalent group containing one or more of these, A, B, and C are substituents, and a, b, and c are each Represents the corresponding number of substitutions of A, B and C (integer from 0 to 3), A, B and C are each independently halogen, carbon number -20 linear or branched alkyl group, C1-20 linear or branched alkoxy group, C1-20 linear or branched alkoxycarbonyl group, cyano group, nitro group or hydroxy The compounds represented by the above general formulas (I) and (II) may have a plurality of the same substituents on the same benzene ring or different substituents. May be.)

  Furthermore, in the manufacturing method of the inclined orientation phase difference film of this invention, it is preferable that the said base material is an orientation process.

  In the method for producing a tilted alignment retardation film of the present invention, the alignment treatment is preferably a rubbing treatment.

  According to the production method of the present invention, in which the liquid crystal composition solution contains a leveling agent and the amount of heat at the time of drying is within a predetermined range, it is possible to obtain a tilted alignment phase difference film that eliminates alignment failure and has excellent uniformity. it can. The tilted alignment retardation film obtained by the present invention can be suitably used as an optical compensation film for an image display device such as a liquid crystal display device.

  In the method for producing a tilted alignment retardation film of the present invention, a coating layer is formed by applying a liquid crystal composition solution containing at least one polymerizable liquid crystal compound, a leveling agent, and a solvent on a substrate. A coating step, and a drying step of drying the coating layer to form a tilt-aligned liquid crystal solidified layer.

  The liquid crystal composition solution includes one or more polymerizable liquid crystal compounds, a leveling agent, and a solvent. The polymerizable liquid crystal compound used in the liquid crystal composition solution is a monomer or an oligomer, and may be used alone or in combination of two or more. The polymerizable liquid crystal compound is preferably a polymerizable nematic liquid crystal compound having one or two or more polymerizable functional groups per molecule, and particularly preferably an acrylic polymerizable liquid crystal compound. As the acrylic polymerizable liquid crystal compound, a bifunctional acrylic monomer is preferable, and among them, a compound that becomes a main chain type liquid crystal polymer after polymerization is preferable.

  Among such acrylic liquid crystal compounds, a polymerizable acrylic monomer represented by the following general formula (I) or (II) can be particularly preferably used.

In the general formulas (I) and (II), at least one of Y _{1 and} Y ₂ is an acrylate group (CH ₂ ═CHCO—) or a methacrylate group (CH ₂ ═C (CH ₃ ) CO—). Y _1, one of _{Y 2} is, when neither of the acrylate group, methacrylate group, _{Y 1} or _{Y 2} is vinyl group, isopropenyl group, 4-vinylphenyl group, 1-chloroethenyl group, an epoxy group, It may be a polymerizable functional group such as a cyanate group or an isocyanate group, and may be hydrogen, halogen, an alkyl group, an alkoxy group, a cyano group, a nitro group, or the like. Among these, from the viewpoint of the orientation of the liquid crystal compound, both Y ₁ and Y ₂ are preferably polymerizable functional groups, and more preferably both are acrylate groups or methacrylate groups.

X ₁ and X ₂ are each independently a covalent bond, a linear or branched alkylene group, an ether group, a carbonyl group, an ester group, a carbonate group, or a divalent group containing one or more thereof.

  A, B, and C represent substituents, and a, b, and c represent the corresponding numbers of substitutions of A, B, and C (integers from 0 to 3), respectively. A, B, and C are each independently monovalent such as halogen, a linear or branched alkyl group having 1 to 20 carbon atoms, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group, or a hydroxy group. It is the basis of. In addition, the compound represented by the general formula (I) or (II) may have a plurality of identical substituents on the same benzene ring, or may have different substituents. .

In particular, from the viewpoint that the liquid crystal molecules have high birefringence and the liquid crystal coating layer can be thinned, the polymerizable liquid crystal compound preferably contains the compound of the general formula (II). In the compound (II), both Y ₁ and Y ₂ are preferably an acrylate group and a methacrylate group. From the wide temperature range showing a liquid crystal phase, both Y ₁ and Y ₂ are acrylate groups. More preferably. X ₁ and X ₂ are preferably those in which an alkylene group and an ether group, a carbonyl group, an ester group, or a carbonate group are linked, and more preferably, the alkylene has 1 to 12 carbon atoms, More preferably, it is 4-10. When the number of carbon atoms of alkylene is small, liquid crystallinity tends to be low (that is, crystallinity is high). On the other hand, if the alkylene group has too many carbon atoms, the isotropic phase transition temperature of the liquid crystal will be lowered. Therefore, as will be described later, when forming the liquid crystal solidified layer by heat drying, the orientation of the liquid crystal molecules should be kept uniform. There is a tendency that the temperature range that can be reduced.

  From the above viewpoint, in the method for producing a retardation film of the present invention, it is preferable to use a compound represented by the following general formula (III) among liquid crystalline compounds.

In the general formula (III), Z is hydrogen, halogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, a cyano group, or a nitro group, and is preferably a chlorine or methyl group. R ₁ and R ₂ are each independently hydrogen or a methyl group, but it is preferable that both R ₁ and R ₂ are hydrogen. X ₃ and X ₄ are each independently an ether group, a carbonyl group, an ester group, or a carbonate group.

  By adding a leveling agent to the liquid crystal composition solution, a retardation film having excellent alignment uniformity on the air interface side can be obtained. As the leveling agent, various compounds such as silicone, fluorine, polyether, acrylic, and titanate can be used. Among them, an acrylic leveling agent is preferably used from the viewpoint of alignment uniformity. In particular, when an acrylic polymerizable liquid crystal compound is used as the polymerizable liquid crystal compound, an acrylic leveling agent is also preferably used from the viewpoint of compatibility with the liquid crystal compound.

  The acrylic leveling agent is excellent in compatibility with the acrylic polymerizable liquid crystal compound as compared with other leveling agents such as a silicone leveling agent. Furthermore, since the acrylic leveling agent has a high surface adjusting ability, it is possible to suppress the thickness variation of the liquid crystal cured layer to be small. Although details of the optical properties of the retardation film obtained by the production method of the present invention will be described later, since the retardation is represented by the product of birefringence and thickness, there is little thickness variation, that is, thickness uniformity. Obtaining a high retardation film is also important for obtaining a retardation film having high optical uniformity.

  In addition, by using such a leveling agent, the molecules of the liquid crystal compound in the coating layer are easily aligned in the normal direction of the substrate, that is, the homeotropic property tends to increase. The reason why the orientation becomes high in this way is not clear, but when the coating layer is formed, the leveling agent is not likely to be unevenly distributed in the form of a thin film on the surface of the coating layer, so that the surface tension does not decrease excessively. Presumed.

  The acrylic leveling agent preferably has a unit represented by the following general formula (IV) in the molecular structure.

R ₃ is hydrogen or a methyl group, and R ₄ is a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched halogenated alkyl group having 1 to 10 carbon atoms, a polyester group, or a poly group. It is an ether group. R ₃ is preferably a perfluoroalkyl group having 1 to 10 carbon atoms.

  The weight average molecular weight Mw measured by the gel permeation chromatograph (GPC) method of the acrylic leveling agent is preferably 2000 to 100,000, more preferably 2500 to 70000, and 3000 to 40000. More preferably. When the molecular weight of the leveling agent is excessively small, the leveling property becomes insufficient, so the orientation on the air interface side may become non-uniform, and when the molecular weight is excessively large, the viscosity of the liquid crystal composition solution increases. The alignment of the liquid crystal may be hindered or the leveling agent may be insoluble.

  A commercial item can be used as such an acrylic leveling agent. Examples of commercially available acrylic leveling agents include the trade name “BYK-340” manufactured by Big Chemie and the trade name “LF-1980” manufactured by Enomoto Kasei.

  The content of the acrylic leveling agent in the liquid crystal composition solution is preferably 0.1 to 1 part by weight, and 0.12 to 0.95 part by weight with respect to 100 parts by weight of the polymerizable liquid crystal compound. It is more preferable that it is 0.15 part by weight to 0.9 part by weight. If the content of the leveling agent is excessively small, the above effects may not be sufficiently obtained. If the amount of the leveling agent is excessively large, the leveling agent is unevenly distributed in the liquid crystal coating layer, and the uniformity of the coating layer may be inferior.

  As the solvent used in the liquid crystal composition solution, the composition containing the polymerizable liquid crystal monomer and the polymerization initiator is excellent in solubility, and when the composition is applied to a substrate, the wettability and composition of the substrate There is no particular limitation as long as it does not cause a decrease in the orientation of the product.

  Specifically, as the solvent, for example, aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene Halogenated hydrocarbons such as chlorobenzene and orthodichlorobenzene, phenols such as phenol and parachlorophenol, ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, anisole, dioxane, tetrahydrofuran, acetone, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone Cyclopentanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, 3-heptanone, Ketones such as heptanone, 2,6-dimethyl-4-heptanone, 2-pyrrolidone, N-methyl-2-pyrrolidone, n-butanol, 2-butanol, cyclohexanol, isopropyl alcohol, t-butyl alcohol, glycerin, Ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, alcohols such as 2-methyl-2,4-pentanediol, amides such as dimethylformamide, dimethylacetamide, acetonitrile, butyronitrile Nitriles such as, cellosolves such as methyl cellosolve and methyl cellosolve, and esters such as ethyl acetate, butyl acetate and methyl lactate can be used. In addition, methylene chloride, carbon disulfide, ethyl cellosolve, butyl cellosolve, and the like can be given as examples of the solvent, but are not limited thereto.

  In addition, from the viewpoint of sufficiently dissolving the composition without substantially eroding the substrate, cyclopentanone, cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, tetrahydrofuran, toluene, or ethyl acetate is used as the solvent. Is preferred.

  These solvents may be used alone or in admixture of two or more. The total solid concentration of the mixed solution varies depending on the solubility, coating viscosity, wettability on the substrate, thickness after coating, etc., but in order to obtain a highly smooth retardation film, the solid concentration is It is preferably 2 to 50% by weight, preferably 5 to 45% by weight, and more preferably 10 to 40% by weight.

  The mixed solution may contain components other than the polymerizable liquid crystal compound, the leveling agent, and the solvent. In particular, for the purpose of the present invention to obtain a tilted alignment phase difference film, it is preferable to include a homeotropic alignment liquid crystal compound. Although it does not restrict | limit especially as a liquid crystal compound of homeotropic orientation, It contains the monomer unit containing the liquid crystalline fragment side chain which has positive refractive index anisotropy, and the monomer unit containing a non-liquid crystalline fragment side chain It is preferable to use a side chain type liquid crystal polymer. As such a liquid crystal compound, for example, those described in JP-A No. 2003-149441 can be used.

  When such a homeotropic alignment liquid crystal compound is used, the amount used is not particularly limited, but is preferably 1 to 80 parts by weight with respect to 100 parts by weight of the polymerizable liquid crystal compound, and 5 to 60 parts by weight. It is more preferable that it is 10 to 50 parts by weight.

  Moreover, it is preferable to use a photoinitiator from the viewpoint of increasing the polymerization rate and reaction rate of the polymerizable liquid crystal compound. There is no restriction | limiting in particular as a photoinitiator, The photoinitiator which consists of a single compound may be sufficient, and what mixed two or more types of different photoinitiators may be sufficient. Examples of the photopolymerization initiator include acetophenone compounds, benzoin compounds, benzophenone compounds, thioxanthone compounds, and the like. Also, for example, trade names “Irgacure 651”, “Irgacure 184”, “Darocur 1173”, “Irgacure 500”, “Irgacure 2959”, “Irgacure 907”, “Irgacure 369”, “Irgacure 369”, manufactured by Ciba Specialty Chemicals Photopolymerization initiators such as “Irgacure 819” and “Irgacure 784” may be used. Further, Merck brand names “Darocur 953” and “Darocur 1116”, and Nippon Kayaku brand names “Kaya Cure MBP”, “Kaya Cure CTX”, “Kaya Cure DITX”, “Kaya Cure CTX”, “Kaya Cure DETX”. It is also possible to use “Kayacure RTX” or the like.

  In addition, an auxiliary agent may be added to the photopolymerization initiator in order to accelerate the polymerization reaction. Examples of the auxiliary agent include triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler's ketone, 4,4′-diethylaminophenone, ethyl 4-dimethylaminobenzoate, Examples thereof include amine compounds such as 4-dimethylaminobenzoic acid (nbutoxy) ethyl and 4-dimethylaminobenzoic acid isoamyl.

  Although there is no restriction | limiting in particular in the addition amount of the said photoinitiator, It is preferable that it is 0.5-20 weight part with respect to 100 weight part of said polymeric liquid crystal compounds, and it is 2-15 weight part. Is more preferable. Moreover, it is preferable that the addition amount of an adjuvant shall be about 0.5 to 2 times amount with respect to a photoinitiator.

  In addition, a polymerization inhibitor may be added to the liquid crystal composition solution for the purpose of suppressing polymerization at an unintended low exposure amount due to light in the process. Examples of the polymerization inhibitor include p-benzoquinone, naphthoquinone, para-xyloquinone, para-toluquinone, 2,6-dichloroquinone, 2,5-diacetoxy-p-benzoquinone, 2,5-dicaproxy-p-benzoquinone, 2, 5-diaeroxy-p-benzoquinone, hydroquinone, pt-butylcatechol, 2,5-dibutylhydroquinone, mono-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, di-t-butyl paracresol 2,4,6-tri-t-butylphenol, hydroquinone monomethyl ether, α-naphthol, acetanidin acetate and the like can be used. The addition amount of the polymerization inhibitor is preferably 0.001 to 3 parts by weight, and more preferably 0.01 to 2 parts by weight with respect to 100 parts by weight of the polymerizable liquid crystal compound. When the addition amount of the polymerization inhibitor is excessively large, the polymerization does not proceed sufficiently even when irradiated with ultraviolet rays in the subsequent step, and the orientation of the liquid crystal cured layer may be insufficient.

  In the method for producing a retardation film of the present invention, the liquid crystal composition solution is coated on a substrate to form a coating layer. The base material is used to uniformly develop the polymerizable liquid crystal compound and other compositions in the solution, and then obtain a uniform alignment state. Examples of the material for forming the base material include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulose resins such as diacetyl cellulose and triacetyl cellulose, acrylic resins such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene. Copolymers, styrene resins, acrylonitrile / styrene resins, acrylonitrile / butadiene / styrene resins, acrylonitrile / ethylene / styrene resins, styrene / maleimide copolymers, styrene / maleic anhydride copolymers and other styrene resins, polycarbonate resins Etc. In addition, cycloolefin resin, norbornene resin, polyolefin resin such as polyethylene, polypropylene, ethylene / propylene copolymer, vinyl chloride resin, amide resin such as nylon and aromatic polyamide, aromatic polyimide, polyimide amide, etc. Imide resins, sulfone resins, polyether sulfone resins, polyether ether ketone resins, polyphenylene sulfide resins, vinyl alcohol resins, vinylidene chloride resins, vinyl butyral resins, arylate resins, polyoxymethylene resins Examples thereof include resins and epoxy resins. Moreover, the polymer film base material etc. which consist of the said resin blend etc. can also be mentioned. Furthermore, metal substrates such as aluminum, iron and copper, glass substrates such as blue plate glass, alkali glass, alkali-free glass, borosilicate glass, flint glass and quartz glass, various substrates such as ceramic substrates, silicon wafers Various semiconductor substrates such as can also be mentioned.

  The substrate may have birefringence or may not have birefringence. By using a film having no birefringence, the obtained retardation film exhibits a phase difference only by the birefringence of the liquid crystal layer, so that control of the optical characteristics becomes easy. Conversely, by using a substrate having birefringence as the substrate, a retardation film having a retardation due to both the birefringence of the substrate and the birefringence of the liquid crystal layer can be obtained. A retardation film having an optical compensation function that cannot be expressed can also be obtained.

  An application layer is formed by applying the polymerizable liquid crystal compound onto a substrate. From the viewpoint of increasing the uniformity of orientation on the substrate, the substrate is preferably subjected to orientation treatment. Examples of the alignment treatment method include rubbing treatment, oblique vapor deposition treatment, microgroove method, stretched polymer film method and the like. From the viewpoint of the ease of the manufacturing process and the high degree of alignment uniformity, it is preferable to use a rubbing process as the alignment processing method.

  Although there is no restriction | limiting in particular as an alignment film used for the said rubbing process, The thing which is excellent in the wettability of the said liquid-crystal composition solution and can align a polymerizable liquid crystal compound in a specific direction is preferable. As such an alignment film, specifically, for example, polyamide, polyimide, lecithin, silica, polyvinyl alcohol, ester-modified polyvinyl alcohol, a polymer in which the degree of saponification of polyvinyl acetate is adjusted, a silane coupling agent, or the like is applied. An alignment film formed as described above can be given. The surface of the substrate may be rubbed as it is.

  The method for applying the liquid crystal composition solution to the substrate is not particularly limited, and a conventionally known method can be used. For example, the solution may be developed into a thin layer by spin coating, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, gravure printing, or the like. The coating thickness is usually 2 to 300 μm, more preferably 2 to 200 μm, and particularly preferably 2 to 50 μm. By setting the thickness within the above range, a retardation film having excellent uniformity of thickness orientation can be produced.

  The coating layer thus obtained is made into a liquid crystal solidified layer by removing the solvent by a drying step of drying by heating. In the present invention, when the atmospheric temperature at the time t in the drying process is T (t), the heat quantity Q represented by the following formula is dried so that 100 <Q <300. A small retardation film can be obtained.

(Where t is the time (minutes) from the start of drying to the end of drying in the drying step, and T (t) is the ambient temperature (° C.) at time t.)

  The drying step may be one that does not involve heating, such as air drying or natural drying, but is preferably heated to 40 ° C. or higher from the viewpoint of removing the solvent and solidifying the coating layer. The drying temperature (atmosphere temperature) in the drying process may be constant or may be changed stepwise. In addition, when the drying temperature in a drying process is constant, the said heat quantity Q is simply represented by the product of drying temperature and drying time. In addition, when drying is performed by changing the drying temperature to two or more stages, the heat quantity Q is the sum of the products of the drying temperature (atmosphere temperature) and the drying time in each stage.

  In view of the uniformity of orientation, the amount of heat Q is more preferably 120 to 280, and further preferably 150 to 250. The maximum value of the atmospheric temperature T (t) in the drying process is more preferably 100 ° C. or less.

  From the viewpoint of fixing the orientation, the maximum value of the temperature T (t) in the drying step is preferably 60 ° C. or higher and 120 ° C. or lower. If the maximum value of the temperature in the drying step is too low, the solvent remains excessively in the liquid crystal solidified layer as described above, so that the orientation may be insufficient and birefringence may be insufficient. Conversely, if the maximum value of the temperature T (t) is too high, orientation defects tend to occur.

  The reason why the alignment becomes uniform due to such temperature conditions is not clear, but in general, in the coating layer before drying, the liquid crystal compound rises in a part of the liquid crystal molecules aligned according to the alignment regulating force on the substrate surface. It is believed that a so-called “reverse tilt” state domain occurs in which the direction is locally reversed. By heating the coating layer having such a domain in the reverse tilt state, the molecular motion (thermal motion) of the liquid crystal compound increases, so that the liquid crystal molecules that have been reverse tilted exceed the alignment regulating force of the substrate, It is considered that the state is aligned according to the pretilt angle of the substrate having a small free energy (high stability), and the reverse tilt state is eliminated, that is, a uniform alignment state is formed. From this point of view, it can be said that the maximum temperature of the atmospheric temperature T (t) in the drying process needs to be sufficient to eliminate the reverse tilt.

  On the other hand, when the drying temperature is too high, the liquid crystal compound exceeds its isotropic phase transition temperature, so that the liquid crystal compound is almost completely released from the alignment regulating force of the substrate to be in an isotropic phase state. After the coating layer is once in the isotropic phase state as described above, the liquid crystal compound is aligned again by the alignment regulating force of the base material when the temperature is lower than the isotropic phase transition temperature. At this time, a reverse tilt state is formed. It is thought that it becomes easy to do. From this viewpoint, it is preferable that the maximum value of the atmospheric temperature T (t) in the drying step is lower than the isotropic phase transition temperature. Even if the temperature is lower than the isotropic phase transition temperature, if the drying time is too long, the proportion of molecules that are released from the orientation regulating force and become in the isotropic phase state increases, so the maximum temperature of T (t) It is considered that it becomes easy to form a reverse tilt state as in the case of high.

  The drying time can be set so that the amount of heat Q becomes an appropriate value from the relationship with the above temperature. However, since the drying time is excessively short, if the value of the amount of heat Q falls below the above range, May remain excessively, that is, the coating layer may be insufficiently solidified, resulting in lack of orientation and insufficient birefringence or orientation defects. Further, when the value of the heat quantity Q exceeds the above range, not only reverse tilt is likely to occur, but also the orientation regulation force is reduced due to thermal contraction of the base material, and there is a case where birefringence is insufficient due to lack of orientation. is there.

  The method for controlling the drying temperature is not particularly limited, but a known heating method using a heater using hot air, microwaves or far infrared rays, a roll heated for temperature adjustment, a heat pipe roll or a metal belt, A temperature control method can be mentioned.

  If the drying temperature has a large variation, unevenness in the thickness of the coating surface and uneven alignment will occur, leading to variations in the retardation of the finally obtained tilted alignment retardation film. Therefore, it is preferable that the temperature variation in the drying process is small. When the tilted alignment phase difference film is produced as a single sheet, it is preferable that the temperature variation in the film plane is small. Moreover, when producing continuously, conveying a film, it is preferable that the temperature variation in the direction orthogonal to a conveyance direction, ie, the width direction, is small.

  The polymerizable liquid crystal compound in the liquid crystal solidified layer thus obtained is preferably a liquid crystal cured layer cured by heat or radiation irradiation. In the present invention, it is preferable to employ radiation curing as a curing method from the viewpoint of maintaining uniformity of orientation. By irradiating with radiation, the polymerizable liquid crystal compound is crosslinked and cured, and the alignment state of the liquid crystal can be fixed.

  Examples of the type of radiation include gamma rays, electron beams, visible rays, ultraviolet rays, and the like, but irradiation with ultraviolet rays is used because of ease of production and high polymerization reactivity. Although the wavelength of the light source in ultraviolet irradiation is determined according to the wavelength region in which the photochemically reactive compound to be used has optical absorption, it is generally preferably 190 nm to 400 nm, and more preferably 250 nm to 380 nm. As the light source having such wavelength characteristics, an ultrahigh pressure mercury lamp, a flash mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a deep UV lamp, a xenon lamp, a xenon flash lamp or a metal halide lamp is preferably used. The ultraviolet light emitted from the light source may be non-polarized light or polarized light.

  There is no restriction | limiting in particular as a position of the light source in the said radiation irradiation, You may arrange | position to the side by which the said mixed solution is apply | coated, and may arrange | position to the opposite base material side. Moreover, there is no restriction | limiting in particular as atmosphere in air | atmosphere in the said radiation irradiation, Air atmosphere, nitrogen atmosphere, argon atmosphere, etc. can be used.

The dose of radiation is not particularly limited, is preferably from 100~1500mJ / cm ^2, and more preferably 100 to 800 mJ / cm ^2. When the irradiation amount is insufficient, the polymerization becomes insufficient and the orientation tends to be poor. Moreover, when it irradiates excessively, an orientation defect may be produced.

  The temperature of the atmosphere at the time of radiation irradiation (also referred to as irradiation temperature) is not particularly limited, but it is preferable to perform radiation irradiation while maintaining the temperature within a range of 20 to 40 ° C. in order to fix a uniform alignment state.

  In the tilted alignment retardation film produced as described above, the range of the thickness of the liquid crystal layer that is aligned and fixed on the substrate includes the birefringence (Δn) of the liquid crystal layer and the required retardation. Although it can select according to this, it is 0.1-10 micrometers normally, It is preferable that it is 0.1-8 micrometers, It is more preferable that it is 0.5-6 micrometers, It is further more preferable that it is 0.5-5 micrometers.

  The light transmittance of such a tilted alignment retardation film is preferably 80% or more at a wavelength of 590 nm, more preferably 85% or more, and still more preferably 90% or more.

  Further, the retardation Re (590) in the film plane of the liquid crystal cured layer measured with light having a wavelength of 590 nm is not particularly limited, but in the case of using for the purpose of improving the display characteristics of the liquid crystal display device, the range of 50 to 1000 nm. It is preferable that it is, and it is more preferable that it is the range of 80-800 nm. Here, Re (590) = (nx−ny) × d, where nx is the refractive index in the slow axis direction of the tilted orientation retardation film (the direction in which the refractive index in the tilted orientation retardation film is maximized). , Ny is the refractive index in the fast axis direction of the tilted alignment retardation film, and d is the thickness of the liquid crystal cured layer.

  The tilted alignment retardation film thus obtained can be used for various optical applications by utilizing the retardation. In particular, the optical compensation of the liquid crystal display device or the optical compensation polarization for the purpose is used. It can use suitably for a board.

  The optical compensation polarizing plate is obtained by laminating the tilted alignment retardation film and the polarizing plate. Generally, a polarizing plate has a polarizer and a protective film on one side or both sides thereof.

  The polarizer is not particularly limited, and various types can be used. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizing layer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizing layers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride and the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with stains and antiblocking agents by washing the polyvinyl alcohol film with water, the polyvinyl alcohol film is also swollen to prevent unevenness such as uneven coloring. is there. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed with dyeing after iodine. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

  Although it does not restrict | limit especially as said transparent protective film, For example, the thermoplastic resin which is excellent in transparency, mechanical strength, heat stability, moisture barrier property, isotropic property etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins. , (Meth) acrylic resins, cyclic olefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. In addition, a transparent protective film is usually bonded to the polarizer by an adhesive layer. As the transparent protective film, thermosetting such as (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone-based, etc. Resin or ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, the high transparency etc. which a thermoplastic resin originally has may not fully be expressed.

  Among the above materials, it is preferable to use at least one selected from a cellulose resin, a polycarbonate resin, a cyclic olefin resin, and a (meth) acrylic resin as the transparent protective film.

  As the cellulose resin, an ester of cellulose and a fatty acid is preferably used. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose, and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercial products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “UZ” manufactured by Fuji Film Co., Ltd. -TAC "and" KC series "manufactured by Konica. In general, these triacetyl cellulose films have an in-plane retardation (Re) of almost zero, but a thickness direction retardation (Rth) of about 60 nm.

  In addition, the cellulose resin film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base film such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). Then, a method of peeling the base film; a solution obtained by dissolving norbornene resin, (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose resin film and dried by heating (for example, 80 And a method of peeling the coated film after about 3 to 10 minutes at about 150 ° C.

  Moreover, as a cellulose resin film with a small thickness direction retardation, the fatty acid cellulose resin film which controlled the substitution degree of the fatty acid can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8. Preferably, the Rth can be reduced by controlling the acetic acid substitution degree to 1.8 to 2.7. By adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid cellulose resin, Rth can be controlled to be small. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  A specific example of the cyclic olefin resin is preferably a norbornene resin. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And the graft polymer which modified these with unsaturated carboxylic acid or its derivative (s), those hydrides, etc. are mentioned. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as cyclic olefin resins. As specific examples, trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, product names “ARTON” manufactured by JSR Corporation, “TOPAS” manufactured by TICONA, and product names manufactured by Mitsui Chemicals, Inc. “APEL” may be mentioned.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  Examples of (meth) acrylic resins include poly (meth) acrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, and methyl methacrylate- (meth) acrylic acid ester copolymer. , Methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer, methyl (meth) acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methacrylic acid) Methyl-methacrylic acid cyclohexyl copolymer, methyl methacrylate- (meth) acrylic acid norbornyl copolymer, etc.). Preferably, poly (meth) acrylic acid C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. These (meth) acrylic resins having a lactone ring structure have high heat resistance, high transparency, high mechanical strength by biaxial stretching, small phase difference, and low photoelastic coefficient. Problems such as unevenness due to distortion of the polarizing plate can be eliminated.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. (Meth) acrylic resins described in Japanese Patent No. 146084 and the like.

  Further, as a transparent protective film, a polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and a substitution in the side chain and And / or a resin composition containing a thermoplastic resin having unsubstituted phenyl and a nitrile group. Specific examples include a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin-layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The transparent protective film is particularly suitable when the thickness is 5 to 150 μm.

  In addition, when providing a transparent protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used.

  In addition, the base material of the tilt alignment retardation film obtained by this invention can also be used as the transparent protective film of a polarizer. Such a configuration is a preferable configuration because the thickness can be reduced by reducing the total number of films and the cost can be reduced.

  The transparent protective film may be subjected to a surface modification treatment before applying the adhesive. Specific examples of the treatment include corona treatment, plasma treatment, primer treatment, and saponification treatment.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  The hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing the reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the prior art. In addition, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer (for example, a backlight-side diffusion plate).

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. Or by applying a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 20 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming the surface fine uneven structure, the amount of fine particles used is generally about 2 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle widening function or the like) for diffusing the light transmitted through the polarizing plate to widen the viewing angle or the like.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  An adhesive is used for the adhesion treatment between the polarizer and the transparent protective film. Examples of the adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, and water-based polyesters. The said adhesive agent is normally used as an adhesive agent which consists of aqueous solution, and contains 0.5 to 60 weight% of solid content normally. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include an ultraviolet curable adhesive and an electron beam curable adhesive. The electron beam curable adhesive exhibits suitable adhesion to the various transparent protective films. In particular, it exhibits good adhesion even with respect to acrylic resins for which it was difficult to satisfy the adhesion.

  In practical use, another optical layer may be laminated and used on the optical compensation polarizing plate on which the tilted alignment retardation film obtained by the present invention is laminated. The optical layer is not particularly limited. For example, the optical layer may be used for the formation of a liquid crystal display device such as a reflecting plate, a transflective plate, the tilted alignment retardation film of the present invention, and other retardation films. Can be used in one or more layers. For example, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on a polarizing plate, an elliptical polarizing plate or a circular polarizing plate in which a retardation film is further laminated on a polarizing plate, or Examples thereof include a polarizing plate in which a brightness enhancement film is further laminated on the polarizing plate.

  Examples of the retardation film include a birefringent film formed by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by the film.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, and polyether sulfone. , Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or any of these binary and ternary copolymers, grafts Examples thereof include polymers and blends. These polymer materials become an oriented product (stretched film) by stretching or the like.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. . Specific examples of the main chain type liquid crystal polymer include a structure in which a mesogenic group is bonded at a spacer portion that imparts flexibility, for example, a nematic alignment polyester liquid crystal polymer, a discotic liquid crystal polymer, and a cholesteric liquid crystal polymer. It is done. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of a conjugated atomic group as a side chain. The thing etc. which have a mesogen part which consists of a cyclic compound unit are mentioned. These liquid crystal polymers are prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment treatment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  The reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one side of the polarizing plate through a transparent protective film or the like as necessary.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects the linearly polarized light with a predetermined polarization axis or the circularly polarized light in a predetermined direction when natural light is incident due to a backlight of a liquid crystal display device or the like or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the improving film and increasing the amount of light that can be used for liquid crystal display by supplying polarized light that is difficult to absorb into the polarizer.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things, such as a thing, can be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and other optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics and the like.

  Furthermore, the inclined alignment phase difference film obtained by the present invention and other various optical members can be provided with an adhesive layer for bonding with other members such as a liquid crystal cell. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency, such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and having excellent weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, from the viewpoints of prevention of foaming and peeling phenomenon due to moisture absorption, deterioration of optical characteristics due to thermal expansion difference and the like, prevention of warpage of liquid crystal cells, and formation of liquid crystal display devices with high quality and excellent durability. An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The attachment of the adhesive layer to each member can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of an appropriate solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator according to the above, and this is applied to a polarizing plate or an optical film. The method of moving up is mentioned.

  The adhesive layer can also be provided on one or both sides of each member as a superposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as the adhesion layers of a different composition, a kind, thickness, etc. in the front and back of a polarizing plate or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive strength, and is generally 1 to 500 μm, preferably 5 to 200 μm, and particularly preferably 10 to 100 μm.

  On the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In addition, each layer such as the polarizer, the transparent protective film, or the adhesive layer includes, for example, a UV absorber such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound. It may be one that has UV absorption ability by a method such as a method of treating with.

  The tilted alignment retardation film obtained by the present invention and the optical compensation polarizing plate formed by laminating the same can be preferably used for forming various image display devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. In other words, a liquid crystal display device is generally formed by assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. As the liquid crystal cell, any type such as a VA mode, an IPS mode, an ECB mode, a TN mode type, an STN mode, and a π type (OCB mode) can be used. In particular, since the tilted alignment retardation film obtained by the present invention is tilted, the field of view of a liquid crystal cell in which liquid crystal molecules are tilted like ECB mode, TN mode, STN mode, and OCB mode. It can be suitably used for optical compensation for the purpose of angle compensation or the like.

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

[Comparative Example 1]
(Preparation of liquid crystal composition solution)
Polymer liquid crystal represented by the following formula (V) (weight average molecular weight: 5000, copolymerization ratio: n = 35) 20 parts by weight, and polymerizable liquid crystal compound represented by the following formula (VI) (manufactured by BASF, 80 parts by weight of the product name “Paliocolor LC242” (abnormal light refractive index = 1.654, normal light refractive index = 1.523) dissolved in 233 parts by weight of cyclopentanone to a solid content concentration of 30% by weight It was. To this solution, 0.3 parts by weight of an acrylic leveling agent (trade name “LF-1980” manufactured by Enomoto Kasei Co., Ltd.) is added, and 7 parts by weight of a polymerization initiator (trade name, manufactured by Ciba Specialty Chemicals). "Irgacure 907") was added. To this solution, 196 parts by weight of cyclopentanone was added to prepare a liquid crystal composition solution having a solid content concentration of 20% by weight.

(Creation of base material)
A triacetyl cellulose film (manufactured by Fuji Film Co., Ltd., trade name “TD80UL”) was rubbed.

(Application)
On the rubbing process surface of the said base material, the said liquid-crystal composition solution was apply | coated uniformly using the wire bar, and the coating layer was formed.

(Dry)
The obtained coating layer was heat-dried for 1 minute in an air circulating thermostat whose atmospheric temperature was adjusted to 60 ° C. to form a solidified layer in which 1.7 μm thick liquid crystal was tilted and aligned.

(Curing)
The surface of the obtained solidified layer is irradiated with ultraviolet rays so that the irradiation amount at a wavelength of 365 nm is 600 mJ / cm ² at room temperature (25 ° C.) to form a tilted aligned liquid crystal cured layer, and a tilt alignment retardation film It was.

[Examples 1-6, Comparative Examples 2-6]
A tilted orientation film was obtained in the same manner as in Comparative Example 1 except that the atmospheric temperature and drying time in the air circulating thermostat during drying were changed as shown in Table 1 below. The numbers in parentheses in Table 1 represent the heat quantity Q.

[Reference Example 1]
In Comparative Example 1, instead of using 20 parts by weight of the polymer liquid crystal represented by the above formula (V) and 80 parts by weight of the polymerizable liquid crystal compound represented by the above formula (VI), A retardation film was obtained in the same manner as in Comparative Example 1 except that 100 parts by weight of the polymerizable liquid crystal compound represented was used. In the obtained retardation film, the liquid crystal layer was horizontally (homogeneously) aligned.

[Reference Examples 2 to 12]
A retardation film in which the liquid crystal layer was horizontally aligned was obtained in the same manner as in Reference Example 1 except that the atmospheric temperature and drying time in the air circulating thermostatic chamber during drying were changed as shown in Table 2 below. The numbers in parentheses in Table 2 represent the heat quantity Q.

  Using the polarizing film (trade name “ECLIPSE E600POL”, manufactured by NIKON) with the retardation film obtained in Examples, Comparative Examples and Reference Examples, the polarization direction (absorption direction) of the analyzer of the microscope in a crossed Nicol state. ) And the slow axis direction of the retardation film were observed in parallel. The observation results (photos) of the examples and comparative examples are shown in FIG. 1, and the observation results (photos) of the reference examples are shown in FIG.

  As can be seen from FIG. 2, in the reference example relating to the horizontally oriented film, light and dark unevenness under crossed Nicols was hardly observed regardless of the drying conditions of the coating layer. On the other hand, in the retardation film tilted as shown in FIG. 1, unevenness in brightness and darkness is observed depending on the drying conditions of the coating layer, but in the retardation film of the example, the unevenness in brightness and darkness is hardly observed. On the other hand, in the retardation film of the comparative example, a white portion where light leaked was observed.

  In addition, the retardation films of Comparative Examples 1 to 5 are arranged so that the slow axis of the retardation film and the polarization direction of the analyzer of the microscope form an angle of 45 ° under crossed Nicols, and the sample is tilted for observation. As a result, the portion that looks black differs depending on the viewing direction. From such a phenomenon, it was found that an alignment defect (reverse tilt) occurred in the retardation film of the comparative example.

  From the above examples, comparative examples, and reference examples, the retardation film in which the liquid crystal is tilted and aligned is more likely to cause alignment failure than the retardation film in which the liquid crystal is horizontally aligned. It can be seen that a highly uniform tilt-oriented retardation film can be obtained without causing defects.

It is an observation photograph in the polarizing microscope (cross Nicol state) of the retardation film obtained by the Example and the comparative example. It is an observation photograph in the polarizing microscope (cross Nicol state) of the retardation film obtained by the reference example.

Claims (8)

An application step of applying a liquid crystal composition solution containing at least one polymerizable liquid crystal compound, a leveling agent, and a solvent on a substrate to form an application layer, and a heat quantity Q represented by the following formula: , A drying step of drying the coating layer under conditions of 100 <Q <300 to form a tilted liquid crystal solidified layer;
The manufacturing method of the inclination orientation retardation film which has this.

(Where t is the time (minutes) from the start of drying to the end of drying in the drying step, and T (t) is the ambient temperature (° C.) at time t.)   The manufacturing method of the inclination orientation retardation film of Claim 1 whose maximum value of the temperature T (t) in the said drying process is 60 degreeC or more and 120 degrees C or less.   The method for producing a tilted alignment phase difference film according to claim 1, wherein the leveling agent contains an acrylic leveling agent. The manufacturing method of the inclination alignment retardation film of Claim 3 whose said acrylic leveling agent is a compound which has a structural unit represented by the following general formula (IV).

(R ₃ is hydrogen or a methyl group, R ₄ is a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched halogenated alkyl group having 1 to 10 carbon atoms, a polyester group, or (It is a polyether group.)   The manufacturing method of the inclination-alignment phase difference film in any one of Claims 1-4 containing an acrylic liquid crystal compound as said polymeric liquid crystal compound. The method for producing a tilted alignment retardation film according to claim 5, wherein the acrylic liquid crystal compound is a compound represented by the following general formula (I) or (II).


(Y ₁ and Y ₂ are each independently acrylate group, methacrylate group, vinyl group, isopropenyl group, 4-vinylphenyl group, 1-chloroethenyl group, epoxy group, cyanate group, isocyanate group, hydrogen, halogen, alkyl group. , An alkoxy group, a cyano group, or a nitro group, and at least one of Y ₁ and Y ₂ is an acrylate group or a methacrylate group, and X ₁ and X ₂ are each independently a covalent bond, linear or branched An alkylene group, an ether group, a carbonyl group, an ester group, a carbonate group, or a divalent group containing one or more of these, A, B, and C are substituents, and a, b, and c are each Represents the corresponding number of substitutions of A, B and C (integer from 0 to 3), A, B and C are each independently halogen, carbon number -20 linear or branched alkyl group, C1-20 linear or branched alkoxy group, C1-20 linear or branched alkoxycarbonyl group, cyano group, nitro group or hydroxy The compounds represented by the above general formulas (I) and (II) may have a plurality of the same substituents on the same benzene ring or different substituents. May be.)   The manufacturing method of the inclination-alignment phase difference film in any one of Claims 1-6 in which the said base material is an orientation process.   The manufacturing method of the inclination orientation retardation film of Claim 7 whose said orientation process is a rubbing process.