JP4593190B2 - Alignment film for aligning liquid crystal material, manufacturing method thereof, alignment liquid crystal film, optical film, and image display device - Google Patents

Description

  The present invention relates to an alignment film for aligning a liquid crystal material and a method for manufacturing the alignment film. The alignment film can obtain an alignment liquid crystal film by aligning a liquid crystal material. The alignment liquid crystal film can be used alone or in combination with other films as an optical film such as a retardation plate, a viewing angle compensation film, an optical compensation film, and an elliptically polarizing film. The alignment film can be used as an alignment film in a liquid crystal cell. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, or a PDP using the alignment film, the alignment liquid crystal film, or the optical film.

  As the liquid crystal display becomes larger, the demand for a wide viewing angle has increased, and various methods have been proposed for the type of liquid crystal cell. In addition, various orientation methods have been studied for optical compensation films used for wide viewing angles. As one of them, there is a method using an alignment liquid crystal film in which a liquid crystal material is aligned using an alignment film.

  As a means for aligning the liquid crystal material, a rubbed alignment film including the manufacture of a liquid crystal cell is often used. However, the rubbed alignment film has problems such as generation of dust and static electricity, and a non-contact process is desired (Non-Patent Document 1).

On the other hand, photo-alignment films obtained in a non-contact manner by light irradiation have been proposed (Non-patent Documents 2 and 3). Formation of the photo-alignment film is classified into photoisomerization, photodimerization, photolysis, photocrosslinking, etc. of the forming material. However, there are also concerns about these photo-alignment films (Non-Patent Document 1). For example, an azo compound, which is a typical compound used for a photoisomerization type alignment film, is inferior in stability over time. Polyvinyl cinnamate, which is a typical compound used for the photo-dimerization type alignment film, has a problem in stability of orientation because dimerization and isomerization proceed simultaneously. In addition, the photodecomposition type alignment film in which a polyimide material is mainly used has a problem that an imidization reaction requires a high temperature and a long time.
liquid crystal. Vol. 3 No. 4 (1999) pp. 262 to 271 liquid crystal. Volume 3 Issue 4 (1999), pages 3-6 Chemical Economy, September 2000, pages 94 to 100

  An object of the present invention is to provide an alignment film having a high alignment property with respect to a liquid crystal material and a method for manufacturing the alignment film.

  The present invention also provides an alignment liquid crystal film obtained using the alignment film, an optical film using at least one alignment liquid crystal film, and an alignment film, an alignment liquid crystal film, or an optical film. An object of the present invention is to provide an image display device using the.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object can be achieved by the following alignment film, and have completed the present invention. That is, the present invention is as follows.

  1. An alignment film for aligning a liquid crystal material formed of a liquid crystal polymer and having anisotropy.

  2. 2. An alignment film for aligning the liquid crystal material as described in 1 above, wherein anisotropy is produced by irradiating the liquid crystal polymer with polarized UV light.

  3. 3. An alignment film for aligning the liquid crystal material according to 1 or 2 above, wherein the liquid crystal polymer is a nematic liquid crystal polymer.

  4). 4. The alignment film for aligning the liquid crystal material according to any one of 1 to 3 above, wherein the nematic liquid crystal polymer is an acrylic liquid crystal polymer containing a nematic liquid crystal monomer as a monomer unit.

5). A method for producing an alignment film for aligning the liquid crystal material according to any one of 1 to 4 above,
A method of producing an alignment film for aligning a liquid crystal material, characterized in that a coating liquid containing a liquid crystal polymer is applied onto a substrate to form a coating film, and then the coating film is irradiated with polarized UV light .

  6). 5. An aligned liquid crystal film obtained by applying a liquid crystal material to the alignment film according to any one of 1 to 4 and aligning the liquid crystal material.

  7). 7. An optical film using at least one oriented liquid crystal film as described in 6 above.

  8). 5. An image display device using the alignment film according to any one of 1 to 4 above, the alignment liquid crystal film according to 6 above, or the optical film according to 7 above.

  Since the alignment film of the present invention is formed of a liquid crystal polymer having anisotropy, the alignment property with respect to the liquid crystal material is high. The liquid crystal polymer for forming the alignment film can be easily formed. The anisotropy of the liquid crystal polymer is obtained, for example, by irradiating polarized UV light. By irradiating the liquid crystal polymer with polarized UV, only molecules in the same direction as the polarized light absorb the UV light and are decomposed. On the other hand, molecules perpendicular to the polarized light do not absorb UV light and therefore remain as they are. As a result, anisotropy occurs in the alignment film surface. By applying and aligning a liquid crystal material on the alignment film, an alignment liquid crystal film in which the liquid crystal material is aligned according to the anisotropy of the alignment film is obtained.

  The alignment film of the present invention is formed of a liquid crystal polymer. Such an alignment film can be formed by applying and curing a liquid crystal monomer, and can also be formed by applying and solidifying a liquid crystal polymer. These film formation methods can be combined. Among these film forming methods, the liquid crystal polymer has lower crystallinity than the liquid crystal monomer and has flexibility and can be easily formed into a film. It is preferable to carry out by coating and solidifying. Hereinafter, a method of forming the alignment film of the present invention by applying and solidifying a liquid crystal polymer will be described. In addition, the liquid crystal monomer illustrated by the following liquid crystal polymer can be used as a liquid crystal monomer used for the said film-forming.

  As the liquid crystal polymer, various polymers exhibiting liquid crystallinity can be used. For example, a nematic liquid crystal polymer is suitable as the liquid crystal polymer. Examples of the nematic liquid crystal polymer include an acrylic liquid crystal polymer containing a nematic liquid crystal monomer as a monomer unit. One or more nematic liquid crystal monomers can be used.

  The nematic liquid crystal monomer has one or more polymerizable functional groups such as an acryloyl group and a methacryloyl group, and has a rigid mesogen group in which two or more cyclic units such as an aromatic ring are connected. Can be given. Examples of the cyclic unit serving as a mesogen group include biphenyl, phenylbenzoate, phenylcyclohexane, azoxybenzene, azomethine, azobenzene, phenylpyrimidine, diphenylacetylene, diphenylbenzoate, and bicyclohexane. Cyclohexyl benzene, terphenyl and the like. Mesogenic groups are cleaved and decomposed by UV irradiation. As the mesogenic group, a biphenyl group or the like is preferable. In addition, the terminal of these cyclic units may have substituents, such as a cyano group, an alkyl group, an alkoxy group, a halogen group, for example. The mesogenic group may be bonded via a spacer portion that imparts flexibility. Examples of the spacer portion include a polymethylene chain and a polyoxymethylene chain. The number of repeating structural units forming the spacer portion is appropriately determined depending on the chemical structure of the mesogenic portion, but the repeating unit of the polymethylene chain is 0 to 20, preferably 2 to 12, and the repeating unit of the polyoxymethylene chain is 0 to 0. 10, preferably 1-3.

  Examples of the nematic liquid crystal monomer include the following general formula (1):

（式中、Ｒ¹は水素原子またはメチル基を、ｍは１〜６の整数を、Ｘ¹は−ＣＯ₂−基、−ＯＣＯ−基、−ＣＯ−、−ＣＨ＝ＣＨ−または−Ｃ≡Ｃ−を、Ｒ²は炭素数１〜６のアルコキシ基、シアノ基、フルオロ基または炭素数１〜６のアルキル基を、ｐおよびｑは１または２を示す。）で表される化合物があげられる。

(Wherein R ¹ represents a hydrogen atom or a methyl group, m represents an integer of 1 to 6, X ¹ represents a —CO ₂ — group, —OCO— group, —CO—, —CH═CH— or —C≡) C-, R ² represents an alkoxy group having 1 to 6 carbon atoms, a cyano group, a fluoro group, or an alkyl group having 1 to 6 carbon atoms, and p and q represent 1 or 2.) It is done.

In the acrylate derivative represented by the general formula (1), p = 1 is preferable, q = 2 is preferable, R ¹ is preferably a hydrogen atom, R ² is preferably a cyano group, and X ¹ is A —COO— group is preferred. Specific examples of the acrylate derivative represented by the general formula (1) include 4- (4-cyanobiphenyloxycarbonyl) phenoxyethyl acrylate, 4- (4-cyanobiphenyloxycarbonyl) phenoxypropyl acrylate, 4 Examples include-(4-cyanobiphenyloxycarbonyl) phenoxybutyl acrylate, 4- (4-cyanobiphenyloxycarbonyl) phenoxypentyl acrylate, 4- (4-cyanobiphenyloxycarbonyl) phenoxyhexyl acrylate, and the like. These may be used alone or in combination.

  Examples of the nematic liquid crystal monomer include the following general formula (2):

（式中、Ｒ₁〜Ｒ₁₂は同一でも異なっていてもよく、−Ｆ、−Ｈ、−ＣＨ₃、−Ｃ₂Ｈ₅または−ＯＣＨ₃を示し、Ｒ₁₃は−Ｈまたは−ＣＨ₃を示し、Ｘ₁は一般式（３）：
−（ＣＨ₂ＣＨ₂Ｏ）_a−（ＣＨ₂）_b−（Ｏ）_c−、を示し、Ｘ₂は−ＣＮまたは−Ｆを示す。但し、一般式（３）中のａは０〜３の整数、ｂは０〜１２の整数、ｃは０または１であり、かつａ＝１〜３のときはｂ＝０、ｃ＝０であり、ａ＝０のときはｂ＝１〜１２、ｃ＝０〜１である。）で表される化合物があげられる。

(In the formula, R _{1 to} R ₁₂ may be the same or different and represent —F, —H, —CH ₃ , —C ₂ H ₅ or —OCH ₃ , and R ₁₃ represents —H or —CH ₃ . X ₁ is represented by the general formula (3):
— (CH ₂ CH ₂ O) _a — (CH ₂ ) _b — (O) _c —, and X ₂ represents —CN or —F. In the general formula (3), a is an integer of 0 to 3, b is an integer of 0 to 12, c is 0 or 1, and when a = 1 to 3, b = 0 and c = 0. Yes, when a = 0, b = 1 to 12, and c = 0 to 1. ).

  As the nematic liquid crystal monomer, the following general formula (4):

（式中、Ｒは水素原子またはメチル基を、ＡおよびＤはそれぞれ独立して１，４−フェニレン基または１，４−シクロヘキシレン基を、Ｘはそれぞれ独立して−ＣＯＯ−基、−ＯＣＯ−基または−Ｏ−基を、Ｂは１，４−フェニレン基、１，４−シクロヘキシレン基、４，４’−ビフェニレン基または４，４’−ビシクロヘキシレン基を、ｍおよびｎはそれぞれ独立して２〜６の整数を示す。）で表される架橋型ネマチック性液晶モノマー等を例示できる。その他、多官能の（メタ）アクリレート系モノマーとしては、前記一般式（４）における末端の「Ｈ₂Ｃ＝ＣＲ−ＣＯ₂−」を、ビニルエーテル基またはエポキシ基に置換した化合物や、「−（ＣＨ₂）_m−」および／または「−（ＣＨ₂）_n−」を「−（ＣＨ₂）₃−Ｃ*Ｈ（ＣＨ₃）−（ＣＨ₂）₂−」または「−（ＣＨ₂）₂−Ｃ*Ｈ（ＣＨ₃）−（ＣＨ₂）₃−」に置換した化合物を例示できる。

(In the formula, R is a hydrogen atom or a methyl group, A and D are each independently 1,4-phenylene group or 1,4-cyclohexylene group, and X is each independently a —COO— group or —OCO group. -Group or -O- group, B is 1,4-phenylene group, 1,4-cyclohexylene group, 4,4'-biphenylene group or 4,4'-bicyclohexylene group, and m and n are each And a cross-linked nematic liquid crystal monomer represented by the following formula: In addition, as the polyfunctional (meth) acrylate monomer, a compound in which the terminal “H ₂ C═CR—CO ₂ —” in the general formula (4) is substituted with a vinyl ether group or an epoxy group, “— ( CH _{2) m} - "and / or" - (CH _{2) n} - "and" _{- (CH 2) 3 -C *} H (CH 3) - (CH 2) 2 - "or" - (CH _{2) 2 -C * H (CH 3) -} (CH 2) 3 - "a substituted compound can be exemplified.

  The acrylic liquid crystal polymer can contain a nematic liquid crystal monomer as a monomer unit and a radically polymerizable non-liquid crystal monomer copolymerizable with the nematic liquid crystal monomer. Examples of the non-liquid crystal monomer include acrylic monomers such as (meth) acrylic acid alkyl ester having a polymerizable functional group such as acryloyl group and methacryloyl group. The proportion of the copolymerization monomer is preferably 50 parts by weight or less with respect to 100 parts by weight of the nematic liquid crystal monomer.

  The method for producing the acrylic liquid crystal polymer is not particularly limited, and living polymerization can be employed in addition to normal radical polymerization. As a polymerization initiator used for radical polymerization, normal radical polymerization such as an azo initiator represented by AIBN (azobisisobutyronitrile), a peroxide initiator represented by BPO (benzoyl peroxide), etc. An initiator is used. The usage-amount of a polymerization initiator is about 0.1-10 weight part normally with respect to 100 weight part of total monomers. The polymerization temperature varies depending on the kind of the polymerization initiator, but is usually about 40 to 10 ° C. After polymerization, purification such as normal reprecipitation can be performed.

  During the living radical polymerization, it is necessary to remove dissolved oxygen in the monomer. Methods for lowering the dissolved oxygen concentration include stirring while blowing an inert gas such as nitrogen or argon, a method of bubbling an inert gas into the monomer, a method of degassing under reduced pressure, a method of degassing by heating, etc. There is. These methods may be used in combination.

  As a polymerization initiator for living radical polymerization, an ester having bromine or chlorine at the α-position or a styrene derivative is suitable. Preferred examples include 2-bromo (or chloro) propionic acid derivatives or chloro (or bromide) 1-phenyl derivatives. Among them, particularly preferred are methyl 2-bromo (or chloro) propionate, ethyl 2-bromo (or chloro) propionate, methyl 2-bromo (or chloro) -2-propionate, 2-bromo (or chloro) -2. -A halogen compound selected from ethyl propionate, 1-phenylethyl chloride (or bromide), and ethyl 2-bromoisobutyrate can be used. As the initiator having a hydroxyl group, for example, 2-hydroxy-2-methylpropionic acid-2-hydroxyethyl can be used. Bifunctional initiators can also be used. Specific examples include ethylene bis (2-bromo-2-methylpropionate).

  In such a polymerization method, a transition metal and a ligand are used as a catalyst other than the initiator. As the transition metal, Cu, Ru, Fe, Rh, V, Ni metal species, and metal salts or metal complexes thereof can be used. The ligand is not particularly limited, and for example, bipyridyl derivatives, amine derivatives, mercaptan derivatives, trifluorate derivatives, and the like can be used. Among these, it is particularly preferable to use Cu (I) and a 2,2′-bipyridyl complex in view of the stability and speed of polymerization.

  The polymerization initiator is generally 0.05 to 30 mol%, preferably 0.1 to 10 mol%, more preferably 0. It is used at a ratio of 1 to 5 mol%. Moreover, the usage-amount of a transition metal is 0.01-3 mol part normally with respect to 1 mol part of said polymerization initiators as forms, such as a halide, Preferably it is used in the ratio of 0.1-1 mol part. . Further, the ligand is used in a proportion of usually 0.5 to 5 mol parts, preferably 1 to 3 mol parts, relative to 1 mol part of the transition metal (form of halide, etc.). When the polymerization initiator and the activator are used in such proportions, good results can be obtained in the reactivity of living radical polymerization, the molecular weight of the produced polymer, and the like.

  In the polymerization method, the monomer component which is liquid at the polymerization temperature can be produced using a solvent or without a solvent. Since the liquid crystal monomer is not usually liquid, it is dissolved in a solvent and polymerized. Any solvent may be used as long as it dissolves the liquid crystal monomer. As the solvent, tetrahydrofuran, anisole, dimethylacetamide, cyclohexanone, cyclopentanone, or the like can be used. Usually, the polymerization is performed at a monomer concentration of about 10 to 60% by weight.

  The polymerization temperature is preferably about 60 to 120 ° C. from the polymerization rate, the catalyst deactivation temperature, and the solubility of the monomer in the solvent. The polymerization time depends on the final number average molecular weight and polymerization temperature, but it is preferable to complete the polymerization in about 3 to 100 hours.

  The number average molecular weight (Mn) of the acrylic liquid crystal polymer is preferably about 500 to 20000, more preferably about 1000 to 10,000. The weight average molecular weight (Mw) is preferably about 500 to 60000, more preferably about 1100 to 20000. The dispersity (Mw / Mn) is preferably about 1 to 3, more preferably about 1.1 to 2. If the value is too high, it takes a long time to polymerize, and it becomes difficult to dissolve in a solvent, making it difficult to handle. The said average molecular weight is a numerical value of polystyrene conversion by GPC (gel permeation chromatography).

  The liquid crystal polymer is applied onto a substrate as a coating liquid to form a coating film. A sensitizer, a reaction accelerator, and other various additives can be blended in the coating solution as long as the properties are not affected. Moreover, a liquid crystal polymer can be used 1 type or in combination of 2 or more types. An alignment film can be obtained by irradiating the obtained coating film with polarized UV light.

  Either the melting method or the solution method may be employed for applying the coating liquid onto the substrate, but it is preferable to use a solution in which a liquid crystal polymer is dissolved in a solvent. The coating method on the substrate is not particularly limited, and can be performed with an appropriate coating machine such as a bar coater, a spin coater, a roll coater, or a gravure coater.

  In the solution coating, examples of the solvent for dissolving the liquid crystal polymer include halogenated hydrocarbons such as chloroform, dichloromethane, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, and chlorobenzene, phenols such as phenol and parachlorophenol, benzene, Aromatic hydrocarbons such as toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, etc., acetone, ethyl acetate, tert-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene bricol monomethyl ether, diethylene glycol Dimethyl ether, ethyl cellosolve, butyl cellosolve, 2-pyrrolidone, N-methyl-2-pyrrolidone, pyridine, triethylamine, tetrahydro Rofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, acetonitrile, butyronitrile, carbon disulfide, methyl ethyl ketone, cyclohexanone, cyclopentanone and the like are preferable. The concentration of the solution is not particularly limited, but is usually about 1 to 50% by weight.

  As the substrate, a metal foil, polyethylene terephthalate, triacetyl cellulose, norbornene resin, polyvinyl alcohol, polyimide, polyarylate, polycarbonate, a sheet or film made of plastic such as polysulfone or polyethersulfone, a glass plate, or a quartz sheet is used. . The thickness in particular of a board | substrate is not restrict | limited, Usually, it is about 10-1000 micrometers.

  After the solution (coating solution) is applied onto the substrate, the solvent is dried and removed. Drying can be performed by heating or air drying. The heating conditions are appropriately determined according to the type of solvent used. Usually, it is performed at about 80 to 120 ° C. for about 0.5 to 5 minutes.

  The dry film thickness of the liquid crystal polymer (alignment film) is usually about 0.01 to 10 μm, preferably 0.05 to 5 μm. When the film thickness of the liquid crystal polymer becomes too thin, there are problems such that it becomes difficult to apply the coating liquid on the base material and it is difficult to apply the coating liquid, or a portion that cannot be applied is formed. If the film thickness becomes too thick, the concentration of the coating solution increases, so that it may be difficult to obtain a smooth film surface, or it may be disadvantageous in terms of cost.

  Irradiation with polarized UV light can be performed using a high-pressure mercury lamp, a metal halide lamp, or the like. Examples of the method for producing polarized light include a method using a prism such as a Grand Taylor prism, a method using a polarizing film, a method using a Brewster angle such as quartz glass, and the like. There is no particular limitation as long as it is a method for producing polarized light. Moreover, it is also possible to obtain the effect of irradiating polarized light by irradiating the liquid crystal polymer coating film obliquely.

  In addition, irradiation with polarized UV light is effective to irradiate light in the light absorption region of liquid crystal molecules in order to decompose the liquid crystal component (mesogenic group), and the irradiation light is adjusted by the type of lamp, filter, etc. Is also possible. In general, liquid crystal molecules often have absorption at a wavelength of 300 nm or less. In this case, it is preferable to irradiate UV light having a wavelength of 300 nm or less.

The UV irradiation amount is usually about 5 to 50 J / cm ² , preferably 10 to 40 J / cm ² . When the UV irradiation amount is small, the reaction for decomposing the liquid crystal component (mesogen group) is insufficient and the orientation becomes small. On the other hand, when the UV irradiation amount is large, the surface of the alignment film is easily deteriorated. The UV irradiation amount refers to UVC (250-260 nm), UVB (280-320 nm), UVA (320-390 nm), and UVV (395-445 nm) measured with an ultraviolet light amount measuring device (manufactured by EIT, UV Power Pack). Refers to the total amount of irradiation light.

  The alignment film of the present invention thus obtained has anisotropy. Anisotropy (%) is measured by the method described in Examples. If the orientation film has a large anisotropy, the orientation of the liquid crystal material applied on the orientation film also increases. Therefore, it is preferable that the anisotropy is somewhat large. On the other hand, when the anisotropy is above a certain level, there is no great difference in the orientation of the liquid crystal material. Therefore, increasing the anisotropy more than necessary is not preferable from the viewpoint of cost and stability of the alignment film. Although anisotropy is expressed by UV irradiation, it is necessary to increase the amount of UV in order to increase the anisotropy, and an increase in the amount of UV irradiation is preferable in terms of cost, surface modification of the alignment film, and the like. Absent. The anisotropy of the alignment film of the present invention is about 15 to 200%, preferably 30 to 100%. This anisotropy is a numerical value obtained by measuring the thickness of the alignment film at 0.1 μm.

  The alignment film thus obtained has a function of aligning liquid crystal materials and the like, and by applying and aligning various liquid crystal materials, various alignment liquid crystals having birefringence due to the alignment of the liquid crystal material. A membrane can be obtained. As the liquid crystal material, any of a liquid crystal monomer and a liquid crystal polymer conventionally used for forming an alignment liquid crystal film can be used without particular limitation. As the liquid crystal monomer and liquid crystal polymer, the liquid crystal monomers and liquid crystal polymers exemplified above can be used, and those other than those described above can be used. Application of the liquid crystal material onto the alignment film may employ either a melting method or a solution method. In the case of the solution method, a solution in which a liquid crystal material is dissolved in a solvent is applied to the alignment film, and then the solvent is dried.

  The alignment of the liquid crystal material is usually performed by heating, but other various means can be used. For example, an alignment liquid crystal film in which a liquid crystal state is fixed can be obtained by heating to a transition temperature of the liquid crystal material and cooling. When the liquid crystal material is a liquid crystal monomer, the liquid crystal material is fixed by being cured by irradiation with radiation such as ultraviolet rays. When the liquid crystal material is a liquid crystal polymer, the liquid crystal material is fixed by cooling below the glass transition point.

  The thickness of the alignment liquid crystal film is determined based on required optical characteristics such as retardation, mechanical characteristics, and the like, and is not particularly limited, but is usually preferably about 0.1 to 20 μm. Preferably it is 0.5-10 micrometers, More preferably, it is 1-5 micrometers. The alignment liquid crystal film thus obtained is used without being peeled from the alignment film, or may be peeled from the alignment film.

  The aligned liquid crystal film thus obtained is used as an optical film. The alignment liquid crystal film can be easily peeled off from the substrate (alignment film). For example, the alignment liquid crystal film can be used as an optical compensation film, a retardation plate, or the like. By applying this optical compensation film and retardation plate to an STN type liquid crystal display device, the display characteristics of the liquid crystal display device, particularly the viewing angle characteristics (wide viewing angle), can be remarkably improved. The optical film using the alignment liquid crystal film can be used in combination with other optical films.

  A polarizing plate is used for an optical film applied to an image display device such as a liquid crystal display device. The polarizing plate usually has a protective film on one side or both sides of the polarizer. The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include hydrophilic polymers such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. And polyene-based oriented films such as those obtained by adsorbing a volatile substance and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, those obtained by stretching a polyvinyl alcohol film and adsorbing and orienting a dichroic material (iodine, dye) are preferably used. The thickness of the polarizer 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 by, for example, 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 of boric acid or potassium iodide. 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 and anti-blocking agent by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

  The protective film provided on one side or both sides of the polarizer preferably has excellent transparency, mechanical strength, thermal stability, moisture shielding properties, isotropic properties, and the like. Examples of the material for the protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymers, and the like. Examples thereof include styrene polymers such as (AS resin) and polycarbonate polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Examples of polymers that form protective films include polymer blends. Other examples include films made of thermosetting or ultraviolet curable resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing a thermoplastic resin having unsubstituted phenyl and a nitrile group. A specific example is 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.

  A transparent substrate that can be particularly preferably used in terms of polarization characteristics and durability is a triacetyl cellulose film whose surface is saponified with an alkali or the like. Although the thickness of a protective film can be determined suitably, generally it is about 10-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 20-300 micrometers is especially preferable, and 30-200 micrometers is more preferable.

  Moreover, it is preferable that a protective film has as little color as possible. Therefore, Rth = [(nx + ny) / 2−nz] · d (where nx and ny are the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film having a retardation value in the film thickness direction of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  The protective film may be a transparent protective film made of the same polymer material on the front and back sides, or may be a protective film made of a different polymer material or the like.

  As the protective film, a cellulose polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. In addition, when providing a protective film in the 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. The polarizer and the protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of aqueous adhesives include polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, aqueous polyurethanes, aqueous polyesters, and the like.

  As the protective film, a hard coat layer, an antireflection treatment, an anti-sticking treatment, or a treatment subjected to diffusion or anti-glare treatment can be used.

  Hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured film having excellent hardness and slipping properties with an appropriate ultraviolet curable resin such as acrylic or silicone is applied to the protective film. It can be formed by a method of adding to the surface. The antireflection treatment is performed for the purpose of preventing 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 conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

  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. It can be formed by imparting a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a blending method of transparent fine particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 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 a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 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 expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

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

  The polarizing plate can be used as an elliptically polarizing plate or a circularly polarizing plate on which retardation plates are laminated. The elliptically polarizing plate or the circularly polarizing plate will be described. These change the linearly polarized light into elliptically polarized light or circularly polarized light, change the elliptically polarized light or circularly polarized light into linearly polarized light, or change the polarization direction of the linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.

  As the phase difference plate, for example, various wavelength plates or those for the purpose of compensating for coloring or viewing angle due to birefringence of the liquid crystal layer can be used, and two types having an appropriate phase difference according to the purpose of use. Optical properties such as retardation can be controlled by laminating the above retardation plates. As the retardation plate, a birefringent film formed by stretching a film made of an appropriate polymer such as polycarbonate, norbornene resin, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate, polyamide, Examples thereof include an alignment film made of a liquid crystal material such as a liquid crystal polymer, and an alignment layer of the liquid crystal material supported by the film. The alignment liquid crystal film can be used as such a retardation plate.

  Moreover, the alignment liquid crystal film obtained by using the alignment film is used as a wide viewing angle polarizing plate by being laminated on a polarizing plate as a viewing angle compensation film as described above. The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen.

  As such a viewing angle compensation retardation plate, a birefringent film that has been biaxially stretched or stretched in two orthogonal directions, a bidirectionally stretched film such as a tilted orientation film, and the like are used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. Can be mentioned. The viewing angle compensation film can be appropriately combined for the purpose of preventing coloring or the like due to a change in viewing angle based on a phase difference caused by a liquid crystal cell or increasing the viewing angle for good viewing.

  In addition, from the viewpoint of achieving a wide viewing angle with good visibility, an optical compensation position in which an alignment layer of a liquid crystal polymer, particularly an optically anisotropic layer composed of a tilted alignment layer of a discotic liquid crystal polymer, is supported by a triacetyl cellulose film. A phase difference plate can be preferably used.

  In addition to the above, the optical layer laminated in practical use is not particularly limited. For example, one or more optical layers that may be used for forming a liquid crystal display device such as a reflective plate or a transflective plate are used. Can do. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which an elliptical polarizing plate or a circular polarizing plate is further laminated with a reflecting plate or a semi-transmissive reflecting plate, or a polarizing plate in which a brightness enhancement film is further laminated on the polarizing plate. Can be given.

  A 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 surface of the polarizing plate via a transparent protective layer or the like as necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or vapor-deposited film made of a reflective metal such as aluminum on one surface of a protective film matted as necessary. In addition, the protective film may include fine particles having a surface fine concavo-convex structure and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. Moreover, the protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it and light and dark unevenness can be further suppressed. The reflective layer with a fine concavo-convex structure reflecting the surface fine concavo-convex structure of the protective film is transparently protected by an appropriate method such as a vapor deposition method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of attaching directly to the surface of the layer.

  The reflective plate can be used as a reflective sheet in which a reflective layer is provided on an appropriate film according to the transparent film, instead of the method of directly imparting to the protective film of the polarizing plate. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a protective film, a polarizing plate or the like is used to prevent a decrease in reflectance due to oxidation, and thus the long-term sustainability of the initial reflectance. More preferable is the point of avoiding the additional attachment of the protective layer.

  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. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.

  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 a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device 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 enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display is reduced, and the image becomes dark. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed toward the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., the brightness unevenness of the display screen is reduced at the same time, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  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.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is incident on the polarizing plate with the polarization axis aligned as it is, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on a polarizer, but from the point of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation layer that functions as a quarter-wave plate for light-color light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method of superposing a retardation layer, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, the cholesteric liquid crystal layer can also be obtained by reflecting circularly polarized light in a wide wavelength range such as a visible light region by combining two or more layers having different reflection wavelengths and having an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or more optical layers as in the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or transflective polarizing plate and a retardation plate are combined may be used.

  The elliptically polarizing plate or the reflective elliptical polarizing plate is obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptical polarizing plate can be formed by sequentially laminating them in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate. An optical film such as an elliptically polarizing plate is advantageous in that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The optical film of the present invention can be provided with an adhesive layer. The pressure-sensitive adhesive layer can be used for adhering to a liquid crystal cell and also used for laminating optical layers. When adhering the optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

  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 being excellent in weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability 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.

  Attachment of the adhesive layer to one side or both sides of the optical film 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 a suitable 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 pressure-sensitive adhesive layer can be provided on one side or both sides of a polarizing plate or an optical film as a superimposed 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 force, and is generally 1 to 500 μm, preferably 5 to 200 μm, 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 ones according to the prior art, such as those coated with an appropriate release agent such as a long mirror alkyl type, fluorine type or molybdenum sulfide, can be used.

  In the present invention, the polarizer, the transparent protective film, the optical film, etc. that form the polarizing plate described above, and the adhesive layer, for example, each include salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, and cyanoacrylates. It may be a compound having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a compound based on nickel or a nickel complex salt compound.

  The optical film of the present invention can be preferably used for forming various 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 appropriately assembling components such as a liquid crystal cell, an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses a film, and it can apply according to the former. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which the optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When providing an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged. The alignment film of the present invention can be used as an alignment film in a liquid crystal cell.

  Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

Examples of the present invention will be described below in more detail, but the present invention is not limited thereto. In addition, the part and% in each example are a weight part.
(Measurement of number average molecular weight and weight average molecular weight)
The polymer was dissolved in THF at 0.1%, and the number average molecular weight and the weight average molecular weight were measured in terms of polystyrene using GPC (gel permeation chromatography). Detailed measurement conditions are as follows.
GPC device: Tosoh HLC-8120GPC
Column: manufactured by Tosoh Corporation, (GMHHR-H) + (GMHHR-H) + (G2000HHR)
Flow rate: 0.8ml / min
Concentration: 0.1%
Injection volume: 100 μl
Column temperature: 40 ° C
Eluent: THF

(Preparation of liquid crystal polymer (1))
In a four-necked flask equipped with a mechanical stirrer, nitrogen introducing tube, cooling tube and rubber septum, the following chemical formula 4:

で示される構造の液晶モノマー（５０ｇ）、ジメチルアセトアミド（１１７ｇ）、２，２−ビピリジン（２．９３ｇ）を加え、系内に２時間窒素を流し置換した。これに窒素気流下、臭化鋼（０．９ｇ）、２−ブロモイソ酪酸エステル（１．２２ｇ）を加え、窒素気流下で、８０℃で４０時間重合した。重合後の溶液をメタノールに加えて再沈、精製を行なって液晶ポリマーを得た。得られた液晶ポリマーは、数平均分子量７８００、重量平均分子量１０１００であった。分散度は１．２９であった。

A liquid crystal monomer (50 g) having a structure represented by the formula, dimethylacetamide (117 g) and 2,2-bipyridine (2.93 g) were added, and the system was substituted by flowing nitrogen for 2 hours. Under this nitrogen stream, steel bromide (0.9 g) and 2-bromoisobutyric acid ester (1.22 g) were added, and polymerization was carried out at 80 ° C. for 40 hours under a nitrogen stream. The solution after polymerization was added to methanol for reprecipitation and purification to obtain a liquid crystal polymer. The obtained liquid crystal polymer had a number average molecular weight of 7,800 and a weight average molecular weight of 10,100. The degree of dispersion was 1.29.

(Preparation of liquid crystal polymer (2))
In a four-necked flask equipped with a mechanical stirrer, nitrogen introduction tube, cooling tube and rubber septum,

で示される構造の液晶モノマー（５０ｇ）、ジメチルアセトアミド（１１７ｇ）を加え、系内に２時間窒素を流し置換した。これに窒素気流下、開始剤としてＡＩＢＮ（０．５ｇ）を加え、窒素気流下で、７０℃で１０時間、さらに８０℃で６時間重合した。得られた液晶ポリマーは、数平均分子量６２００、重量平均分子量７９００であった。分散度は１．２７であった。

A liquid crystal monomer (50 g) having a structure represented by the formula (1) and dimethylacetamide (117 g) were added, and the system was purged with nitrogen for 2 hours. AIBN (0.5 g) was added as an initiator under a nitrogen stream, and polymerization was performed at 70 ° C. for 10 hours and further at 80 ° C. for 6 hours under a nitrogen stream. The obtained liquid crystal polymer had a number average molecular weight of 6200 and a weight average molecular weight of 7900. The degree of dispersion was 1.27.

(Polarized UV irradiation)
Using a high-pressure mercury lamp as a light source, the light was converted into polarized light by a cranter prism and irradiated with polarized UV light at 25 ° C. using a conveyor type UV irradiation device. When measured with an ultraviolet light quantity measuring device (EIT, UV Power Pack), UVC (250-260 nm), UVB (280-320 nm), UVA (320-390 nm), and UVV (395) are passed through the conveyor once. -445 nm) was 1.0 J / cm ² in total.

(anisotropy)
Anisotropy can be evaluated by the following method. Using a spectrophotometer (manufactured by Hitachi, U-3410), absorbance at a wavelength of 250 to 600 nm was measured using polarized light produced by attaching a Grand Taylor prism at the exit. The measurement was performed by setting the sample so that the polarization direction when the sample was irradiated with polarized UV and the polarization direction of the spectrophotometer were parallel and orthogonal. Absorbance of the substrate was excluded, the parallel and orthogonal absorbances were measured, and the anisotropy was calculated by the following equation at the wavelength where the absorbance was maximum.
Anisotropy (%) = {(absorbance when orthogonal -absorbance when parallel) / (absorbance when parallel)} × 100.

Example 1
A 1% concentration solution was prepared by dissolving 1 part of the liquid crystal polymer (1) in 99 parts of cyclopentanone. The solution was applied onto a quartz glass plate by a spin coater and dried at 100 ° C. for 1 minute to obtain a coating film having a thickness of 0.1 μm. Then, this coating film was passed through the conveyor 20 times and irradiated with polarized UV of 20 J / cm ² . The obtained film was evaluated for anisotropy. The results are shown in Table 1.

Example 2
A 2% concentration solution was prepared by dissolving 2 parts of the liquid crystal polymer (2) in 98 parts of cyclopentanone. The solution was applied onto a quartz glass plate by a spin coater and dried at 100 ° C. for 1 minute to obtain a coating film having a thickness of 0.2 μm. Then, this coating film was passed through the conveyor 20 times and irradiated with polarized UV of 20 J / cm ² . The obtained film was evaluated for anisotropy. The results are shown in Table 1.

Comparative Example 1
In Example 1, the same operation as in Example 1 was performed except that polyvinyl cinnamate (manufactured by Aldrich) was used instead of the liquid crystal polymer (1). The obtained film was evaluated for anisotropy. The results are shown in Table 1.

Comparative Example 2
In Example 1, the same operation as in Example 1 was performed except that non-polarized UV was irradiated instead of irradiation with polarized UV. The obtained film was evaluated for anisotropy. The results are shown in Table 1.

Comparative Example 3
In Example 1, the same operation as in Example 1 was performed except that polymethyl methacrylate was used instead of the liquid crystal polymer (1). The obtained film was evaluated for anisotropy. The results are shown in Table 1.

  The orientations of the films obtained in Examples and Comparative Examples were evaluated by the following method. The results are shown in Table 1.

(Orientation)
On the obtained film, an ethyl acetate solution (solid content 10%) of a liquid crystal monomer (Paliocolor LC242: manufactured by BASF) was applied with a spin coater, and then immediately dried to form a liquid crystal layer having a liquid crystal monomer thickness of 1 μm. Formed. This was heated and oriented at 100 ° C. for 2 minutes to obtain a liquid crystal film. The obtained liquid crystal film was sandwiched between crossed Nicol polarizers, visually observed, and the orientation was evaluated according to the following criteria. ○: Transparent. Δ: Slightly cloudy. X: It is cloudy.

実施例で得られたは、異方性が高く、液晶材料に対する配向性もよく、液晶材料を配向させるための配向膜として有用であることが分かる。

It was found that the examples obtained have high anisotropy, good alignment with the liquid crystal material, and are useful as an alignment film for aligning the liquid crystal material.

Claims (5)

An alignment film for aligning a liquid crystal material,
It is formed of a liquid crystal polymer and has optical anisotropy,
The optical anisotropy is caused by irradiating polarized UV to a liquid crystal polymer,
The liquid crystal polymer is a nematic liquid crystal polymer containing, as a monomer unit, one or more selected from a nematic liquid crystal monomer represented by the following [Chemical Formula 1] and a nematic liquid crystal monomer represented by the following [Chemical Formula 2]. An alignment film for aligning the liquid crystal material.

A method of producing an alignment film for aligning the liquid crystal material according to claim 1 Symbol placement,
A method of producing an alignment film for aligning a liquid crystal material, characterized in that a coating liquid containing a liquid crystal polymer is applied onto a substrate to form a coating film, and then the coating film is irradiated with polarized UV light . The liquid crystal material is applied to the alignment film of claim 1 Symbol placement, alignment liquid crystal film obtained by orienting a liquid crystal material. An optical film using at least one oriented liquid crystal film according to claim 3 . An image display device using claim 1 Symbol placement of the alignment layer, alignment liquid crystal film according to claim 3, or the optical film according to claim 4, wherein.