JP2008026438A - Composite polarizing plate, its manufacturing method, composite optical member and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite polarizing plate made thinner than the conventional composite polarizing plate while keeping the optical performance equal to that of the conventional composite polarizing plate, a method for manufacturing the composite polarizing plate, and a composite optical member and a liquid crystal display device in each of which the composite polarizing plate is used. <P>SOLUTION: The composite polarizing plate 10 is constituted so that a transparent protective film 12 is stuck to one surface of a polarizer 11 and a retardation plate 15 consisting of a transparent resin, a primer layer 16 and a coating retardation layer 17 containing an organically-modified clay complex and a binder resin are formed in this order on the other surface of the polarizer while interposing an adhesive layer 13 between the polarizer and the retardation plate. The method for manufacturing the composite polarizing plate comprises the steps of: forming the primer layer 16 on the surface of the retardation plate 15; forming the coating retardation layer 17 on the surface of the primer layer 16 to obtain a layered retardation plate 23; sticking the transparent protective film 12 to one surface of the polarizer 11 to prepare a polarizing plate 21; and sticking the retardation plate 15-located side of the layered retardation plate 23 to the polarizer 11-located side of the polarizing plate 21 while interposing the adhesive layer 13 between them. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a composite polarizing plate used by being attached to a liquid crystal cell, a method for producing the same, a composite optical member using the composite polarizing plate, and a liquid crystal display device.

  In recent years, liquid crystal display devices have rapidly spread as information display devices such as mobile phones, portable information terminals, computer monitors, and televisions by taking advantage of low power consumption, low voltage operation, light weight, and thinness. Yes. With the development of liquid crystal technology, liquid crystal display devices of various modes have been proposed, and problems such as response speed, contrast, and narrow viewing angle are being solved. However, it is still pointed out that the viewing angle is narrower than that of a cathode ray tube (CRT), and various attempts have been made to expand the viewing angle.

  As one of such liquid crystal display devices, there is a vertical alignment (VA) mode liquid crystal display device in which rod-like liquid crystal molecules having positive or negative dielectric anisotropy are aligned perpendicular to a substrate. In such a vertical alignment mode, in the non-driven state, the liquid crystal molecules are aligned perpendicular to the substrate, so that light passes through the liquid crystal layer without changing the polarization. For this reason, by arranging linearly polarizing plates on the top and bottom of the liquid crystal panel so that the polarization axes are orthogonal to each other, almost complete black display can be obtained when viewed from the front, and a high contrast ratio can be obtained. it can.

  However, in the VA mode liquid crystal display device having only the polarizing plate in such a liquid crystal cell, the axial angle of the disposed polarizing plate is deviated from 90 ° when viewed obliquely. Due to the birefringence of the rod-like liquid crystal molecules in the cell, light leakage occurs and the contrast ratio is significantly reduced.

  In order to eliminate such light leakage, it is necessary to arrange an optical compensation film between the liquid crystal cell and the linear polarizing plate. Conventionally, one biaxial retardation plate is provided between the liquid crystal cell and the upper and lower polarizing plates. The specification to arrange, the specification to arrange the positive uniaxial retardation plate and the complete biaxial retardation plate one by one above and below the liquid crystal cell or both on one side of the liquid crystal cell are adopted. I came. For example, Japanese Patent Laid-Open No. 2001-109009 (Patent Document 1) discloses that in a vertical alignment mode liquid crystal display device, a plate (that is, a positive uniaxial retardation plate) is disposed between upper and lower polarizing plates and a liquid crystal cell. ) And c-plate (ie, a complete biaxial retardation plate).

A positive uniaxial retardation plate is a film in which the ratio R ₀ / R _th of the in-plane retardation value R ₀ to the retardation value R _{th in the} thickness direction is approximately 2, and is completely biaxial. A retardation film is a film having an in-plane retardation value R _{0 of} substantially zero. Here, the refractive index in the in-plane slow axis direction of the film is n _x , the refractive index in the in-plane fast axis direction (the direction perpendicular to the slow axis in the plane) is n _y , and the thickness direction of the film When the refractive index is n _z and the thickness of the film is d, the in-plane retardation value R ₀ and the thickness direction retardation value R _th are defined by the following expressions (I) and (II), respectively.

_{R 0 = (n x -n y} ) × d (I)
R _th = [(n _x + _ny ) / 2−n _z ] × d (II)

The positive uniaxial film, since the n _z ≒ n _y, the R ₀ / R _th ≒ 2. Even in the case of a positive uniaxial film, R ₀ / R _th may vary between about 1.8 and 2.2 due to fluctuations in stretching conditions. The perfectly biaxial film, for the n _x ≒ n _y, the R ₀ ≒ 0. A complete biaxial film is a film having negative uniaxiality and having an optical axis in a normal direction because only the refractive index in the thickness direction is different (small). , Sometimes called c-plate.

  One of the complete biaxial films (c plates) as described above includes a coating layer containing an organically modified clay complex. For example, Japanese Patent Laid-Open No. 2005-338215 (Patent Document 2) discloses a coating plate having a refractive index anisotropy on a retardation plate made of a transparent resin film oriented in-plane via an adhesive layer. It is disclosed that a phase difference layer is laminated to form a composite phase difference plate, and that a polarizing plate is also laminated on the resin phase difference plate side. Japanese Patent Laid-Open No. 2006-10912 (Patent Document 3) discloses that a composition containing a urethane resin based on an aliphatic diisocyanate as a binder and an organically modified clay complex is formed into a film. A retardation plate is disclosed, and it is also described that the retardation plate is laminated on a polarizing plate via an adhesive layer to form a composite polarizing plate. In the configurations disclosed in the examples of Patent Document 2 and Patent Document 3, both polarizing plates have protective films on both sides of the polarizer.

JP 2001-109909 A (Claim 15 and paragraph 0036) JP 2005-338215 A JP 2006-10912 A

  The present inventors laminated a polarizing plate with a retardation plate made of a transparent resin and a coating retardation layer having refractive index anisotropy to form a composite polarizing plate. On the other hand, the surface of the retardation plate made of the transparent resin is used to form a coating retardation layer via a primer layer, and the resulting laminated retardation plate is transparent. By laminating the phase difference plate surface made of resin on the polarizer side (side without the transparent protective film) of the polarizing plate through an adhesive layer, it has been found that a thinner composite polarizing plate can be produced than before, The present invention has been reached.

  Accordingly, an object of the present invention is to provide a composite polarizing plate thinner than the conventional one and a method for manufacturing the same while maintaining the optical performance equivalent to that of the conventional product. Another object of the present invention is to provide a composite optical member thinner than the conventional one by laminating an optical layer exhibiting another optical function on this composite polarizing plate. Still another object of the present invention is to provide a liquid crystal display device that can be made thinner by using these composite polarizing plates or composite optical members.

  According to the present invention, a transparent protective film is bonded to one surface of a polarizer, and the other surface is provided with a phase difference plate made of a transparent resin, a primer layer, and organically modified clay via an adhesive layer. There is provided a composite polarizing plate in which a coating retardation layer containing a composite and a binder resin is formed in this order.

  This composite polarizing plate can be manufactured through the following steps.

A primer layer forming step of forming a primer layer on the surface of a phase difference plate made of a transparent resin;
A coating phase difference is formed by applying a coating liquid containing an organically modified clay complex and a binder resin in an organic solvent to the surface of the primer layer, and removing the solvent from the coating liquid to form a coating phase difference layer. A layer forming step, and separately, a polarizing plate having a transparent protective film bonded to one side of a polarizer, and the phase difference plate side made of a transparent resin of the laminated phase difference plate obtained in the coating phase difference layer forming step And a bonding step of bonding the polarizing plate side of the polarizing plate through an adhesive layer.

  Moreover, according to this invention, the composite optical member by which the optical layer which shows another optical function was laminated | stacked on said composite polarizing plate is also provided.

  Furthermore, according to the present invention, there is also provided a liquid crystal display device in which the above-described composite polarizing plate or composite optical member is disposed on at least one surface of a liquid crystal cell.

  In the composite polarizing plate of the present invention, conventionally, one of the protective films (liquid crystal cell side) disposed on both sides of the polarizer is removed, and an adhesive layer is attached between the polarizer and the resin phase difference plate, thereby reducing the conventional polarizing plate. It can be made thinner than anything. Therefore, the liquid crystal display device to which the composite optical member in which the composite polarizing plate or an optical layer exhibiting other optical functions is laminated can also be made thinner than the conventional one.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings as appropriate. FIG. 1 is a schematic cross-sectional view showing a layer configuration example of a composite polarizing plate according to the present invention. In the present invention, a transparent protective film 12 is bonded to one surface of the polarizer 11, and the other surface is provided with a phase difference plate 15, a primer layer 16 and a coating phase difference made of a transparent resin via an adhesive layer 13. Layer 17 is laminated in this order to form composite polarizing plate 10. The polarizing plate 21 is a state in which the transparent protective film 12 is bonded to one surface of the polarizer 11, and the primer layer 16 and the coating retardation layer 17 are laminated on the retardation plate 15 in this order. The laminated phase difference plate 23 is used. An adhesive layer 18 for bonding to a liquid crystal cell or the like can be provided outside the coating retardation layer 17.

  The polarizer 11 can be a polarizing film made of a conventionally known polyvinyl alcohol resin. Specific examples include a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin film, and a polyene oriented film in which a polyvinyl alcohol resin is partially dehydrated. Among these, a film obtained by adsorbing and orienting a dichroic dye on a polyvinyl alcohol-based resin film is preferably used. There are iodine-based polarizing films using iodine as a dichroic dye and dye-based polarizing films using a dichroic organic dye as a dichroic dye, both of which can be used. The thickness of the polarizer 11 is, for example, about 10 to 50 μm. Examples of the polyvinyl alcohol resin constituting the polarizer 11 include polyvinyl alcohol, which is a saponified product of polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl formal, and poly (ethylene-acetic acid) obtained by modifying polyvinyl alcohol with aldehydes. Vinyl) copolymer saponified product and the like.

  The transparent protective film 12 bonded to one surface of the polarizer 11 may be generally known as a protective film for a polarizing plate, and is made of, for example, a cellulose-based resin such as triacetyl cellulose, diacetyl cellulose, or cellulose acetate butyrate. Film, film made of polyolefin resin which is a polymer mainly composed of olefin such as propylene and ethylene, film composed of cyclic polyolefin resin which is polymer mainly composed of polycyclic cyclic olefin such as norbornene A film etc. can be used. Especially, the film which consists of a cellulose resin and the film which consists of polyolefin resin is mentioned as a preferable thing. Among cellulose resin films, acetyl cellulose resin films such as triacetyl cellulose and diacetyl cellulose are excellent in optical transparency and are effective protective layers when laminated with a polarizer. One. The thickness of the transparent protective film 12 is, for example, about 10 to 200 μm.

  A transparent adhesive is generally used for bonding the polarizer 11 and the transparent protective film 12. Examples of suitable adhesives include aqueous solutions of polyvinyl alcohol resins commonly used in this field. Polyvinyl alcohol resins used as adhesives include partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, as well as carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. It may be a modified polyvinyl alcohol resin. In addition, a crosslinkable additive such as glyoxal or a water-soluble epoxy resin can be blended with the adhesive made of an aqueous solution of a polyvinyl alcohol resin.

  The phase difference plate 15 bonded to the other surface of the polarizer 11 is made of a transparent resin, and is generally configured by being oriented in the plane. The resin used for this is not particularly limited as long as it is excellent in transparency and uniform, but a stretched film of a transparent thermoplastic resin is preferably used from the viewpoint of easy production of an oriented film. Specific examples of the thermoplastic resin include, for example, polycarbonate, polyarylate, polysulfone, polyethersulfone, cellulosic resin, polyolefin resin that is a polymer mainly containing olefin such as propylene and ethylene, and polycyclic such as norbornene. And cyclic polyolefin resins, which are polymers having a cyclic olefin of the formula as a main monomer. A retardation plate 15 can also be used in which a coating layer made of a liquid crystalline substance or the like is provided on a transparent resin substrate such as a cellulose-based resin to develop a retardation.

  The in-plane retardation value of the resin retardation plate 15 may be appropriately selected from the range of about 30 to 300 nm depending on the use of the composite polarizing plate. For example, when the composite polarizing plate is applied to a relatively small liquid crystal display device such as a mobile phone or a portable information terminal, the resin retardation plate 15 is advantageously a quarter wavelength plate.

  The primer layer 16 formed on the surface of the resin phase difference plate 15 is advantageously a transparent resin formed by coating. The primer generally means an undercoat, but the primer layer 16 in the present invention functions as an undercoat layer of the retardation layer 17 formed by coating. Further, due to the presence of the primer layer 16, even if the coating liquid for the coating retardation layer 17 is applied, the influence on the resin retardation plate 15 by the organic solvent in the coating liquid can be prevented. The primer layer 16 is made of a resin that does not exhibit elasticity as much as the pressure-sensitive adhesive. The type of the resin is not particularly limited, but is preferably excellent in coating property, and particularly excellent in transparency and adhesion after layer formation.

  The resin constituting the primer layer 16 may be used in a state of being dissolved in a solvent, or itself has a layer forming ability, but in order to adjust the film thickness, the resin is diluted with a solvent and used. Also good. Depending on the solubility of the resin, aromatic hydrocarbons such as benzene, toluene and xylene, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and isobutyl acetate, chlorine such as methylene chloride, trichloroethylene and chloroform A general organic solvent such as hydrocarbons, alcohols such as ethanol, 1-propanol, 2-propanol, and 1-butanol can also be used. However, if the primer layer 16 is formed from a solution containing an organic solvent, the optical properties of the resin retardation plate 15 may be affected. Therefore, it is preferable to form the primer layer 16 from a coating solution using water as a solvent. .

  A suitable example of the resin constituting the primer layer 16 is an epoxy resin. As the epoxy resin, either a one-component curable type or a two-component curable type can be used. A water-soluble epoxy resin is particularly preferable. The water-soluble epoxy resin is, for example, a polyamide epoxy obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a polycarboxylic acid such as adipic acid and epichlorohydrin. It can be a resin. Commercially available products of such polyamide epoxy resins include “Smiles Resin 650 (30)” and “Smiles Resin 675” (both trade names) sold by Sumika Chemtex Co., Ltd.

  When a water-soluble epoxy resin is used as the resin for forming the primer layer 16, it is preferable to mix other water-soluble resins such as a polyvinyl alcohol resin in order to further improve the coatability. Polyvinyl alcohol resins are modified such as partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, as well as carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. Polyvinyl alcohol resin may be used. A commercially available product of a suitable polyvinyl alcohol resin is “KL-318” (trade name), which is an anionic group-containing polyvinyl alcohol sold by Kuraray Co., Ltd.

  When the primer layer 16 is formed from a coating solution containing a water-soluble epoxy resin, it is preferable that the epoxy resin has a concentration in the range of about 0.2 to 10 parts by weight per 100 parts by weight of water. Moreover, when mix | blending a polyvinyl alcohol-type resin with this coating liquid, it is preferable that the quantity shall be about 1-20 weight part per 100 weight part of water. The thickness of the primer layer 16 is preferably in the range of about 0.1 to 10 μm.

  In forming the primer layer 16, the coating method to be used is not particularly limited, and various known coating methods such as a direct gravure method, a reverse gravure method, a die coating method, a comma coating method, and a bar coating method are used. be able to.

  A coating retardation layer 17 is formed on the primer layer 16. The coating retardation layer 17 is a layer formed by applying a coating liquid containing an organically modified clay complex and a binder resin in an organic solvent, and removing the solvent therefrom.

  Here, the organically modified clay complex is a complex of an organic substance and a clay mineral, specifically, for example, a complex of a clay mineral having a layered structure and an organic compound, and an organic solvent. It is dispersible. Examples of the clay mineral having a layered structure include a smectite group and a swellable mica, and its cation exchange ability makes it possible to form a complex with an organic compound. Among them, the smectite group is preferably used because it is excellent in transparency. Examples of those belonging to the smectite group include hectorite, montmorillonite, and bentonite. Among these, those chemically synthesized are preferable from the viewpoints of few impurities and excellent transparency. In particular, synthetic hectorite having a controlled particle size is preferably used because scattering of visible light is suppressed.

  Examples of organic compounds that are complexed with clay minerals include compounds that can react with oxygen atoms and hydroxyl groups of clay minerals, and ionic compounds that can be exchanged for exchangeable cations. Although there will be no restriction | limiting in particular if it can swell or disperse | distribute to a solvent, Specifically, a nitrogen-containing compound etc. can be mentioned. Examples of the nitrogen-containing compound include primary, secondary or tertiary amines, and quaternary ammonium compounds. Of these, quaternary ammonium compounds are preferably used because cation exchange is easy.

  Two or more organic modified clay composites can be used in combination. Commercially available products of suitable organically modified clay composites include composites of synthetic hectorite and quaternary ammonium compounds sold under the trade names “Lucentite STN” and “Lucentite SPN” by Co-op Chemical Co., Ltd. There is a body.

  Such an organically modified clay complex dispersible in an organic solvent is used in combination with a binder resin from the viewpoints of ease of coating on the primer layer 16, development of optical properties, mechanical properties, and the like. The binder resin used in combination with the organically modified clay complex is preferably one that dissolves in an organic solvent such as toluene, xylene, acetone, or ethyl acetate, especially one having a glass transition temperature of room temperature or lower (about 20 ° C. or lower). It is done. Moreover, in order to obtain the good heat-and-moisture resistance and handling properties required when applied to a liquid crystal display device, those having hydrophobic properties are desirable. Examples of such a preferable binder resin include aldehyde-modified polyvinyl alcohol resins such as polyvinyl butyral, polyvinyl formal, and polyvinyl acetal, cellulose resins such as cellulose acetate butyrate, acrylic resins such as butyl acrylate, urethane resins, and methacrylic resins. Resins, epoxy resins, polyester resins and the like can be mentioned.

  Commercially available binder resins include polyvinyl alcohol aldehyde-modified resins sold under the trade name “Denkabutyral # 3000-K” by Denki Kagaku Kogyo Co., Ltd., and “Aron S1601” from Toagosei Co., Ltd. There are acrylic resins sold under the trade name, and isophorone diisocyanate-based urethane resin sold under the trade name “SBU Lacquer 0866” by Sumika Bayer Urethane Co., Ltd.

  The ratio of the organic modified clay complex dispersible in the organic solvent and the binder resin is in the range of 1: 2 to 10: 1, particularly in the range of 1: 1 to 2: 1, in the former: latter weight ratio. It is preferable for improving mechanical properties such as preventing cracking of the coating retardation layer 17 composed of an organically modified clay composite and a binder resin.

  The organic modified clay complex and the binder resin are applied onto the primer layer 16 in a state of being contained in an organic solvent. In general, the binder resin is dissolved in an organic solvent, and the organic modified clay complex is dispersed in the organic solvent. The solid content concentration of this dispersion is not limited unless the dispersion after preparation is gelled or clouded within a practical range, but usually the total solid content of the organically modified clay complex and the binder resin. Is used in a range of about 3 to 15% by weight. The optimal solid content concentration varies depending on the types of the organic modified clay complex and the binder resin and the composition ratio of the both, and is thus set for each composition. Moreover, you may add various additives, such as a viscosity modifier for improving the applicability | paintability at the time of film forming, and a crosslinking agent for improving hydrophobicity and / or durability further.

  The coating solution for forming the coating retardation layer 17 containing the organic modified clay composite and the binder resin in an organic solvent preferably has a chlorine content of 2,000 ppm or less. The organically modified clay complex is often mixed with impurities containing chlorine due to the raw materials used in the production thereof. If such a chlorine compound is used in a large amount, there is a possibility of bleeding out from the film after forming the retardation layer 15 by coating. In that case, when the composite polarizing plate is bonded to the liquid crystal cell glass via the pressure-sensitive adhesive layer, the adhesive strength is significantly reduced over time. Therefore, it is preferable to remove the chlorine compound from the organically modified clay complex by washing, and if the chlorine content in the organic modified clay complex is 2,000 ppm or less, such a decrease in adhesive strength can be suppressed. The removal of the chlorine compound can be performed by a method of washing the organically modified clay complex with water.

  The coating phase difference layer coating liquid preferably has a moisture content measured by a Karl Fischer moisture meter in the range of 0.15 to 0.35% by weight. When the water content exceeds 0.35% by weight, phase separation occurs in a water-insoluble organic solvent, and the coating liquid tends to separate into two layers. On the other hand, when the water content is less than 0.15% by weight, the haze value tends to increase when the coating retardation layer is formed. The moisture measurement method includes a drying method, a Karl Fischer method, a dielectric constant method, and the like. Here, the Karl Fischer method, which can easily measure a minute unit, is adopted.

  The method for adjusting the water content of the coating liquid for coating retardation layer to the above range is not particularly limited, but a method of adding water to the coating liquid is simple and desirable. When the organic solvent, the organic modified clay complex and the binder resin as used in the present invention are mixed by a usual method, the water content of 0.15% by weight or more is hardly exhibited. Therefore, it is preferable that the water content is within the above range by adding a small amount of water to the coating liquid in which the organic solvent, the organic modified clay complex and the binder resin are mixed. The method of adding water is effective at any time during the coating liquid preparation process, and is not particularly limited.However, after a certain period of time has elapsed in the coating liquid preparation process, the water content is measured after sampling. The method of adding a predetermined amount of water is preferable in that the water content can be controlled with good reproducibility and accuracy. Note that the amount of added water may not match the measurement result with the Karl Fischer moisture meter. As the cause, it is considered that a part of the water causes an interaction (for example, adsorption) with the organic modified clay complex. However, if the moisture content measured by the Karl Fischer moisture meter is kept at 0.15 to 0.35% by weight, the haze value of the resulting coating retardation layer can be kept low.

  The coating method used to form the coating retardation layer 17 is not particularly limited, and various known coatings such as a direct gravure method, a reverse gravure method, a die coating method, a comma coating method, and a bar coating method are used. Can be used.

The refractive index anisotropy in the thickness direction of the retardation layer 17 is represented by a thickness direction retardation value _Rth defined by the above formula (II), and this value is obtained with the in-plane slow axis as the tilt axis. It can be calculated from the phase difference value R ₄₀ measured by tilting 40 degrees and the in-plane phase difference value R ₀ . That is, the thickness direction retardation value R _th according to the formula (II) is the in-plane retardation value R ₀ , the retardation value R ₄₀ measured with the slow axis as the tilt axis, and the thickness d of the film. , and using the mean refractive index n ₀ of the film to obtain the n _x, n _y and n _z numerically from the following formula (III) ~ (V), by substituting them into the formula (II), calculated can do.

_{R 0 = (n x -n y} ) × d (III)
R ₄₀ = (n _x −ny _y ) × d / cos (φ) (IV)
(n _x + _ny + _nz ) / 3 = n ₀ (V)
here,
φ = sin ^-1 [sin (40 °) / n ₀ ]
n _y ′ = _ny × _nz / [ _ny ² × sin ² (φ) + _nz ² × cos ² (φ)] ^1/2

The thickness direction retardation R _th of the phase difference layer 17, from the range of about 40 to 300 nm, their use, in particular according to the characteristics of the liquid crystal cell is preferably selected as appropriate. The thickness direction retardation value R _th is preferably 50 nm or more, and more preferably 200 nm or less.

  An adhesive layer 18 can be formed on the coating retardation layer 17 as necessary. Adhesives, also called pressure sensitive adhesives, are adhered to the surface of other substances simply by pressing them, and when they are peeled off from the adherend surface, they can be removed with almost no trace as long as the adherend has strength. It is a viscoelastic body. The pressure-sensitive adhesive layer 18 can be composed of an acrylic polymer, a silicone-based polymer, polyester, polyurethane, polyether or the like as a base polymer. In particular, like acrylic adhesives, it has excellent optical transparency, retains appropriate wettability and cohesion, has excellent adhesion to substrates, and has weather resistance and heat resistance. However, it is preferable to select and use a material that does not cause peeling problems such as floating and peeling under the conditions of heating and humidification. The acrylic adhesive is composed of an alkyl ester of acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, or a butyl group, and (meth) acrylic acid or hydroxyethyl (meth) acrylate. An acrylic copolymer having a weight average molecular weight of 100,000 or more, which is blended with a functional group-containing acrylic monomer so that the glass transition temperature is preferably 25 ° C. or lower, more preferably 0 ° C. or lower, is used as the base polymer. Useful.

  The pressure-sensitive adhesive layer 18 can be formed by a method in which a pressure-sensitive adhesive solution mainly composed of the base polymer as described above is applied and dried, and a pressure-sensitive adhesive layer is formed on the release treatment surface of the film subjected to the release treatment. It can also be formed by preparing a prepared film (film with pressure-sensitive adhesive) and sticking it to the surface of the coating retardation layer 15 on the pressure-sensitive adhesive layer side.

  A laminate in which a primer layer 16 and a coating retardation layer 17 are formed in this order on a retardation plate 15 and a polarizer 11 side of a polarizing plate 21 having a transparent protective film 12 bonded to one surface of the polarizer 11. The phase difference plate 23 is bonded to the phase difference plate 15 side via the adhesive layer 13. The adhesive layer 13 is not particularly limited as long as it is transparent and can adhere the polarizer 11 and the resin retardation plate 15, and can be composed of, for example, an adhesive. The pressure-sensitive adhesive is also called a pressure-sensitive adhesive, as described above for the pressure-sensitive adhesive layer 18, and adheres to the surface of another substance simply by pressing it. It is a viscoelastic body that can be removed with almost no trace if the kimono has strength. As an example of an adhesive, the thing similar to having demonstrated the adhesive layer 18 above can be mentioned.

  Next, the manufacturing method of the composite polarizing plate of this invention is demonstrated. As described above, the composite polarizing plate of the present invention can be produced through the following steps.

A primer layer forming step of forming the primer layer 16 on the surface of the phase difference plate 15 made of a transparent resin;
Coating that coats the surface of the primer layer 16 with a coating solution containing an organically modified clay complex and a binder resin in an organic solvent, and removes the solvent therefrom to form a coating retardation layer 17 From the phase difference layer forming step, and separately from the transparent resin of the laminated phase difference plate 23 obtained in the coating phase difference layer forming step by preparing the polarizing plate 21 having the transparent protective film 12 bonded to one side of the polarizer 11. The bonding process which bonds the phase difference plate 15 side which becomes and the polarizer 11 side of the said polarizing plate 21 through the contact bonding layer 13. FIG.

  When the pressure-sensitive adhesive layer 18 is provided outside the coating retardation layer 17, any one of the above steps, for example, at the end of the coating retardation layer forming step, or after all the steps are finished and the composite polarizing plate is manufactured. The pressure-sensitive adhesive layer 18 can be provided.

  Taking the case where the pressure-sensitive adhesive layer 18 is provided at the end of the coating retardation layer forming step as an example, this manufacturing method is divided into steps or used members, and is shown in a schematic cross-sectional view in FIG. First, in the primer layer forming step, the primer layer 16 is formed on the surface of the phase difference plate 15 as shown in FIG. At this time, the phase difference plate 15 is preferably subjected to corona discharge treatment on both surfaces thereof. Next, in the coating retardation layer forming step, a coating retardation layer 17 is formed on the surface of the primer layer 16 as shown in FIG. Thereafter, as shown in FIG. 2C, the pressure-sensitive adhesive layer 18 is formed on the surface of the coating retardation layer 17 to obtain a laminated phase difference plate 24 with the pressure-sensitive adhesive layer. Furthermore, in the bonding step, a polarizing plate 21 having a transparent protective film 12 bonded to one surface of the polarizer 11 shown in FIG. 2D is prepared, and as shown in FIG. The phase difference plate 15 side of the layered phase difference plate 24 with layers (the layered phase difference plate 23 when the adhesive layer 18 is not provided) and the polarizer 11 side of the polarizing plate 21 are bonded via the adhesive layer 13. The composite polarizing plate 10 is used.

  The example in the case of manufacturing a roll-shaped composite polarizing plate with this form was shown with the cross-sectional schematic diagram in FIG. In this example, first, a primer layer coating solution is applied to the surface of the retardation plate 15 fed from the retardation plate feed roll 30 via the primer layer coating machine 31, and then passes through the primer layer drying zone 33. And dried to form a coating retardation layer. Also in this case, the phase difference plate 15 is preferably subjected to corona discharge treatment on both surfaces thereof. Next, a phase difference layer coating solution is applied to the surface of the primer layer of the phase difference plate 22 with a primer layer (see FIG. 2A) via the coating layer coating machine 36, and subsequently the coating layer drying zone 38. The laminated phase difference plate 23 (see FIG. 2B) is dried. Then, this lamination | stacking phase difference plate 23 is used for bonding with the film 19 with an adhesive. The film 19 with an adhesive here is a film having an adhesive layer provided on a release film as described above, and the film 19 with an adhesive fed out from the film feed roll 40 with an adhesive is Then, the laminated phase difference plate 23 is supplied to the coating phase difference layer surface so as to be laminated on the pressure-sensitive adhesive layer side, and both are laminated to obtain the laminated phase difference plate 24 with the pressure-sensitive adhesive layer. After passing through the winding roll 42 in this state, it is used for pasting with a polarizing plate.

  In the bonding step, first, on the polarizer side of the polarizing plate 21 (as described with reference to FIG. 1, a transparent protective film is bonded to one surface of the polarizer) fed out from the delivery roll 50. The film with adhesive 14 fed out from another delivery roll 44 is supplied so as to be bonded on the side of the adhesive layer, and the adhesive is bonded to the polarizer. The film 14 with an adhesive here is a film in which the adhesive layer 13 described above with reference to FIG. 1 is provided on a release film. After the adhesive layer is stuck on the polarizer of the polarizing plate 21, the release film is peeled off and taken up by the release film take-up roll 46. And the said adhesive layer side of the polarizing plate 21 in which the adhesive layer was formed is bonded to the resin phase difference plate side of the laminated phase difference plate 24 with the pressure-sensitive adhesive layer after passing through the winding roll 42 described above. , 54 to obtain a composite polarizing plate 10 as a product. Thereafter, the composite polarizing plate 10 is wound around the product roll 60.

  Although FIG. 3 shows an example in which the process until the composite polarizing plate 10 with the adhesive is obtained with a consistent line, this line can be divided into an appropriate number as necessary. For example, a laminated retardation plate 23 in which a primer layer and a coating retardation layer are formed in this order on the retardation plate 15, or a laminated retardation plate 24 with an adhesive layer in which an adhesive layer is formed on the coating retardation layer side. At this stage, it can be wound up on a roll once. Further, for example, until the laminated phase difference plate 23 is obtained, the film can be once wound on a roll at the stage of the phase difference plate 22 with a primer layer in which a primer layer is formed on the phase difference plate 15.

  In FIG. 3, the curved arrow represents the rotation direction of the roll. Moreover, although the adhesive layer and the adhesive layer showed the form which bonds the film 19 with an adhesive, or the film 14 with an adhesive on the adhesive layer side or the adhesive layer side, an adhesive coating liquid or adhesive coating was shown. A pressure-sensitive adhesive layer or an adhesive layer can also be provided by a method of applying the liquid.

  The composite polarizing plate obtained as described above can be laminated on an optical layer exhibiting other optical functions to form a composite optical member. An example of the layer structure of the composite optical member is shown in a schematic cross-sectional view in FIG. In this example, an optical layer 71 showing another optical function is laminated on the transparent protective film 12 side of the composite polarizing plate 10 shown in FIG. For example, a pressure-sensitive adhesive can be used for the lamination of both, and this is shown as a pressure-sensitive adhesive layer 72 in FIG. Examples of the optical layer 71 exhibiting other optical functions include those conventionally used in the formation of liquid crystal display devices, such as a brightness enhancement film. The brightness enhancement film is an optical film that can increase the use efficiency of backlight in a liquid crystal display device. Examples of brightness enhancement films include “DBEF”, which is a reflective polarizing separation film sold by 3M Company [Sumitomo 3M Co., Ltd. in Japan], and “BEF”, which is an upward prism sheet also sold by 3M Company. Can be mentioned.

  When using an adhesive for bonding of the other optical layer 71, the adhesive similar to what was previously demonstrated about the adhesive layer 18 in the figure with reference to FIG. 1 can be used.

  A composite polarizing plate 10 as shown in FIG. 1 and a composite optical member 70 as shown in FIG. 4 can be arranged on at least one surface of a liquid crystal cell to form a liquid crystal display device. The composite polarizing plate 10 can also be arrange | positioned on both surfaces of a liquid crystal cell. Moreover, the composite polarizing plate 10 can be disposed on one surface of the liquid crystal cell, and the composite optical member 70 can be disposed on the other surface. The composite polarizing plate 10 or the composite optical member 70 may be disposed on one side of the liquid crystal cell, and another polarizing plate may be disposed on the other surface of the liquid crystal cell with a retardation plate as necessary. . As described in the background art section, the liquid crystal cell is preferably a vertical alignment (VA) mode, but the liquid crystal cell of the present invention is also applicable to other types of liquid crystal cells such as a bend alignment (ECB) mode. The polarizing plate or the composite optical member functions effectively.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. The compositions of the primer layer coating solution and the coating retardation layer coating solution used in the following examples are as follows.

[Primer layer coating solution]
As a water-soluble epoxy resin, “Sumirez Resin 650 (30)” (trade name, aqueous solution with a solid content of 30%), which is a polyamide epoxy resin manufactured by Sumika Chemtex Co., Ltd., is also used as a polyvinyl alcohol resin ( "KL-318" (trade name) which is an anionic group-containing polyvinyl alcohol manufactured by Kuraray Co., Ltd. and blended with the following composition.

  This coating solution is mixed with polyvinyl alcohol “KL-318” while warming water to 100 ° C., stirred, cooled to room temperature, and further mixed with polyamide epoxy resin “Smileze Resin 650 (30)”. Prepared.

[Coating liquid for coating retardation layer]
As an organically modified clay complex, “Lucentite STN” (trade name) manufactured by Corp Chemical Co., which is a complex of synthetic hectorite and trioctylmethylammonium ions, and polyurethane based on isophorone diisocyanate as a binder resin. "SBU Lacquer 0866" (trade name) manufactured by Sumika Bayer Urethane Co., Ltd., which is a resin varnish with a solid content of 30%, is blended with the following composition.

  The organically modified clay composite used here was obtained by a manufacturer after washing with acid after producing synthetic hectorite before organic modification, organically modifying it, and further washing with water. The amount of chlorine contained therein was 1,111 ppm. This coating solution was prepared by mixing with the above composition, stirring, and filtering through a filter having a pore size of 1 μm, and the water content measured with a Karl Fischer moisture meter was 0.25%. The weight ratio of the solid content of the organically modified clay complex / binder resin in this coating solution is 6/4.

[Example 1]
(A) Production of laminated retardation plate First, a 28 μm thick retardation plate (“CSES430120Z-S-KY” manufactured by Sumitomo Chemical Co., Ltd., in-plane retardation value of 120 nm), which is a uniaxially stretched film of norbornene resin. Corona discharge treatment was performed on both sides of the plate. Next, the primer layer coating solution was applied on one side and dried at 80 ° C. for about 1 minute to form a primer layer having a water content of about 20%. Next, the coating liquid for coating retardation layer was applied on the primer layer, and then dried at 90 ° C. for 3 minutes to form a coating retardation layer. Subsequently, an acrylic pressure-sensitive adhesive (“P-3132” manufactured by Lintec Co., Ltd.) was stuck on the coating retardation layer, and the resin phase difference plate / primer layer / coating retardation layer / adhesive layer in this order. A laminated retardation plate was obtained.

(B) Production of composite polarizing plate Separately, a polarizing plate in which a 40 μm thick transparent protective film made of triacetyl cellulose is bonded to one surface of a polyvinyl alcohol-iodine polarizer [manufactured by Sumitomo Chemical Co., Ltd.] "SR066A-HC"] is prepared, and an adhesive ("L1" manufactured by Lintec Co., Ltd.) is applied to the surface without the transparent protective film. The plate side was bonded and the composite polarizing plate with an adhesive layer was obtained. The layer structure of the composite polarizing plate produced in this example is as shown in FIG.

(C) Thickness measurement of composite polarizing plate The composite polarizing plate with the pressure-sensitive adhesive layer prepared in (b) above was cut into a width of 25 mm and a length of about 850 mm, and the digital length measuring instrument “MH-” manufactured by Nikon Corporation was cut. Nine points of thickness were measured in the length direction using 15M ". The results of 9-point average are shown in Table 1.

(D) Evaluation of optical performance of composite polarizing plate The composite polarizing plate with the pressure-sensitive adhesive layer prepared in (b) above is cut into 25 mm square, and bonded to soda glass on the pressure-sensitive adhesive layer side, and then the pressure in the autoclave is increased. A pressure treatment was carried out at 5 kgf / cm ² and a temperature of 50 ° C. for 20 minutes. Next, the thickness direction retardation value, polarization degree and haze value were measured by the following methods. The results are shown in Table 1.

(D1) Thickness direction retardation value: measured using a phase difference measuring device “KOBRA-WR” manufactured by Oji Scientific Instruments.
(D2) Polarization degree: Measured using a spectrophotometer “UV-2400” manufactured by Shimadzu Corporation.
(D3) Haze value: Measured using a haze meter “HZ-1” manufactured by Suga Test Instruments Co., Ltd.

[Comparative Example 1]
(A) Preparation of Composite Polarizing Plate A polarizing plate “SRW062AP6-HC2” made by Sumitomo Chemical Co., Ltd., separately prepared on the resin phase difference plate side of the laminated phase difference plate produced in (a) of Example 1. (Polyester in which both sides of a polarizer with iodine adsorbed and oriented on polyvinyl alcohol are sandwiched between 40 μm thick triacetyl cellulose films and a pressure-sensitive adhesive layer is formed on one side) are bonded on the pressure-sensitive adhesive layer side And the composite polarizing plate with an adhesive layer was produced. The layer structure of the composite polarizing plate obtained in this example is shown in a schematic cross-sectional view in FIG. That is, the composite polarizing plate 80 includes a triacetyl cellulose film 82 / a polarizer 81 / a triacetyl cellulose film 82 / an adhesive layer 83 / a resin retardation plate 85 / a primer layer 86 / a coating retardation layer 87 / an adhesive layer 88. It has a layer structure.

(B) Thickness measurement of composite polarizing plate The composite polarizing plate with the pressure-sensitive adhesive layer prepared in (a) above was cut into a width of 25 mm and a length of about 850 mm, and a digital length measuring device “MH-” manufactured by Nikon Corporation was obtained. Nine points of thickness were measured in the length direction using 15M ". The results of 9-point average are shown in Table 1.

(C) Evaluation of optical performance of composite polarizing plate The composite polarizing plate with the pressure-sensitive adhesive layer prepared in the above (a) was cut into 25 mm square, and bonded to soda glass on the pressure-sensitive adhesive layer side, and then the pressure in the autoclave. A pressure treatment is performed at 5 kgf / cm ² and a temperature of 50 ° C. for 20 minutes, and then the thickness direction retardation value, polarization degree and haze value are obtained in the same manner as in (d1) to (d3) of Example 1. The results are shown in Table 1.

  As can be seen from the comparison between the above Examples and Comparative Examples, the composite polarizing plate of the present invention can be made thinner than that of the conventional product (Comparative Example 1) while exhibiting optical performance equivalent to that of the conventional product (Comparative Example 1).

It is a cross-sectional schematic diagram which shows the layer structural example of the composite polarizing plate which concerns on this invention. It is a cross-sectional schematic diagram which divides and shows an example of the manufacturing method of a composite polarizing plate for every process or a use member. It is a cross-sectional schematic diagram which shows the example in the case of manufacturing a composite polarizing plate in roll shape. It is a cross-sectional schematic diagram which shows the layer structural example of a composite optical member. 6 is a schematic cross-sectional view showing a layer structure of a composite polarizing plate produced in Comparative Example 1. FIG.

Explanation of symbols

10 ... Composite polarizing plate,
11 ... Polarizer,
12 ... Transparent protective film,
13 …… Adhesive layer
14 …… Adhesive film,
15 ... retardation plate made of transparent resin,
16 …… Primer layer,
17 …… Coating retardation layer,
18 …… Adhesive layer,
19 …… Adhesive film,
21 …… Polarizing plate,
22 ... retardation plate with primer layer,
23 …… Laminated retardation plate,
24 …… Laminated retardation plate with adhesive layer,
30 ... retardation plate feed roll,
31 …… Primer layer coating machine,
33 …… Primer layer drying zone,
36 …… Coating layer coating machine,
38 ... coating layer drying zone,
40: Film feed roll with adhesive layer,
42 ... winding roll,
44 .. Film feed roll with adhesive,
46 …… Release film take-up roll,
50 …… Polarizer feed roll,
53, 54 ... Bonding roll,
60 …… Product roll,
70 …… Composite optical member,
71 ... an optical layer exhibiting other optical functions,
72 …… Adhesive layer,
80. Composite polarizing plate of Comparative Example 1,
81 ... Polarizer,
82 …… Triacetylcellulose film,
83 …… Adhesive layer,
84: Polarizing plate,
85 ... retardation plate,
86 …… Primer layer,
87 …… Coating retardation layer,
88 …… Adhesive layer.

Claims (13)

  A transparent protective film is bonded to one surface of the polarizer, and on the other surface, a retardation plate made of a transparent resin, a primer layer, and an organically modified clay complex and a binder resin via an adhesive layer The composite polarizing plate characterized by the above-mentioned.   The composite polarizing plate according to claim 1, wherein the polarizer is obtained by adsorbing and orienting a dichroic dye on a polyvinyl alcohol-based resin film.   The composite polarizing plate according to claim 1, wherein the transparent protective film bonded to one surface of the polarizer is made of a cellulose resin or a polyolefin resin.   The phase difference plate which consists of transparent resin consists of a transparent resin film orientated in the surface, The composite polarizing plate in any one of Claims 1-3.   The composite polarizing plate according to claim 1, wherein the primer layer is made of a transparent resin.   The composite polarizing plate according to claim 5, wherein the primer layer contains an epoxy resin.   The composite polarizing plate according to claim 5, wherein the primer layer is formed from a composition containing a water-soluble epoxy resin and a polyvinyl alcohol-based resin.   The composite polarizing plate according to claim 7, wherein the water-soluble epoxy resin is a polyamide epoxy resin.   The composite polarizing plate according to claim 1, wherein the adhesive layer is composed of an adhesive. A primer layer forming step of providing a primer layer on the surface of a phase difference plate made of a transparent resin,
A coating phase difference is formed by applying a coating liquid containing an organic modified clay complex and a binder resin in an organic solvent to the surface of the primer layer, and removing the solvent from the coating liquid to form a coating phase difference layer. A layer forming step, and separately, a polarizing plate having a transparent protective film bonded to one side of a polarizer, and the phase difference plate side made of a transparent resin of the laminated phase difference plate obtained in the coating phase difference layer forming step And a polarizing step of bonding the polarizing plate side of the polarizing plate through an adhesive layer.   An optical layer exhibiting another optical function is laminated on the composite polarizing plate according to claim 1.   A liquid crystal display device, wherein the composite polarizing plate according to claim 1 is disposed on at least one surface of a liquid crystal cell.   A liquid crystal display device comprising the composite optical member according to claim 11 disposed on at least one surface of a liquid crystal cell.

Images