CN101490586A - Composite polarizing plate, manufacturing method thereof, composite optical member, and liquid crystal display device - Google Patents

Abstract

The invention provides 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, moreover a method for manufacturing the composite polarizing plate, and a composite optical member and a liquid crystal display device using the composite polarizing plate. The invention provides a composite polarizing plate (10) wherein a transparent protection film (12) is bonded to one side of a polarizer (11), and a transparent resin film (13), a primer layer (14) and a coating retardation layer (15) containing an organic modified clay composite and a binder resin are formed on the other side of the polarizer (11) in this order. This composite polarizing plate is produced by a process comprising a step for forming the primer layer (14) on the surface of the transparent resin film (13), a step for forming the coating retardation layer (15) on the surface of the primer layer (14), and a step for bonding the transparent protection film (12) to one side of the polarizer (11) and bonding the transparent resin film (13) provided with the coating retardation layer (15) to the other side of the polarizer (11) with the transparent resin film (13) side facing the polarizer, respectively using an adhesive.

Description

Composite polarizing plate, manufacturing method thereof, composite optical member, and liquid crystal display device

technical field

The present invention relates to a composite polarizing plate to be bonded to a liquid crystal cell, a manufacturing method thereof, a composite optical member using the composite polarizing plate, and a liquid crystal display device.

Background technique

In recent years, liquid crystal display devices have been rapidly popularized as information display devices such as mobile phones, mobile information terminals, monitors for computers, and televisions due to their low power consumption, low-voltage operation, light weight, and thin shape. 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 has been pointed out that the viewing angle is narrower than that of a cathode ray tube (CRT), and various attempts to widen the viewing angle have been made.

As one of such liquid crystal display devices, there is a vertical alignment (VA) mode liquid crystal display device in which rod-shaped liquid crystal molecules having positive or negative dielectric constant anisotropy are vertically aligned with respect to a substrate. In this type of vertical alignment mode, since the liquid crystal molecules are vertically aligned with respect to the substrate in a non-driven state, light passing through the liquid crystal layer is not accompanied by changes in polarization. Therefore, by arranging the linear polarizing plates so that the upper and lower polarization axes of the liquid crystal panel are perpendicular to each other, a substantially complete black display can be obtained when viewed from the front, and a high contrast ratio can be obtained.

However, in a VA-mode liquid crystal display device having only a polarizing plate on such a liquid crystal cell, when it is observed from an oblique direction, since the axis angle of the polarizing plate disposed deviates from 90° and the rod-shaped Since the liquid crystal molecules show birefringence, light leakage occurs, and the contrast ratio is remarkably lowered.

In order to eliminate this kind of light leakage, it is necessary to arrange an optical compensation film between the liquid crystal cell and the linear polarizing plate. In the past, a two-way retardation film was arranged between the liquid crystal cell and the upper and lower polarizing plates, or in the A positive unidirectional retardation plate and a complete bidirectional retardation plate are respectively arranged on the upper and lower sides of the liquid crystal cell, or both are arranged on one side of the liquid crystal cell.

For example, in JP-A-2001-109009 (claim 15 and paragraph 0036), it is described that in a vertical alignment mode liquid crystal display device, between the upper and lower polarizing plates and the liquid crystal cell, a plate (plate) (that is, Positive unidirectional retardation plate) and c-plate (ie, fully bidirectional retardation plate).

A positive unidirectional retardation film is a film in which the ratio R0/Rth of the retardation value R0 in the plane to the retardation value Rth in the thickness direction is approximately 2. In addition, a fully bidirectional retardation film is a film with an in-plane retardation A film with a value R0 of roughly 0. Wherein, the refractive index in the direction of the slow axis in the plane of the film is nx, the refractive index in the direction of the advancing axis in the plane of the film (the direction perpendicular to the slow axis in the plane) is ny, and the film When the refractive index in the thickness direction is nz and the thickness of the film is d, the retardation value R0 in the plane and the retardation value Rth in the thickness direction are defined by the following formulas (I) and (II), respectively.

R0＝(nx—ny)×d (I)

Rth＝[(nx+ny)/2—nz]×d (II)

，所以成为

。即使在正的单向性薄膜中，R0/Rth也会由于拉伸条件的变动而在1.8～2.2左右之间变化。在完全双向性的薄膜中，成为

，所以成为

。在完全双向性的薄膜中，由于只有厚度方向的折射率不同(小)，所以具有负的单向性，也被称为光学轴处于法线方向的薄膜，另外，如上所述，有时也被称为c板。In a positive unidirectional film, becomes

, so becomes

. Even in a positive unidirectional film, R0/Rth will vary between 1.8 and 2.2 due to changes in stretching conditions. In a fully bidirectional film, becomes

, so becomes

. In a completely bidirectional film, since only the refractive index in the thickness direction is different (small), it has negative unidirectionality, and it is also called a film whose optical axis is in the normal direction. In addition, as mentioned above, it is sometimes called called c-plate.

As one of the completely bidirectional films (c-plates) described above, there is a film composed of a coating layer containing an organically modified clay composite. For example, JP-A-2005-309290 discloses a composite polarizing plate in which a polarizing plate, an adhesive layer, and a retardation plate composed of a coating layer having refractive index anisotropy are sequentially laminated as the coating layer. As an example, a coating layer formed from a coating solution containing an organically modified clay composite and a binder resin can be mentioned. As a method for producing this composite polarizing plate, after forming a coating layer on a transfer substrate, laminating the exposed surface of the coating layer on the side of the adhesive layer of a polarizing plate having an adhesive layer, followed by The method by which the coating layer is released from the transfer substrate. In Japanese Patent Laid-Open No. 2005-338215, it is disclosed that on a retardation plate composed of an in-plane oriented transparent resin film, a coated retardation layer having an anisotropic refractive index is laminated through an adhesive layer to form a composite retardation film. plate, it is also described that a polarizing plate is laminated on the side of the resin retardation film. In addition, JP-A No. 2006-10912 discloses that a polyurethane resin made of aliphatic diisocyanate into a paste is used as a binder, and a composition containing this and an organically modified clay complex is formed into a film. The retardation plate also describes that the retardation plate is laminated on the polarizing plate through an adhesive layer to form a composite polarizing plate. In the structures disclosed in these JP-A-2005-309290 or JP-A-2006-10912, a phase difference plate consisting of a polarizing plate and a coating layer is adhered via an adhesive layer or has Protective film.

Contents of the invention

The inventors of the present invention have found that when a composite polarizing plate is formed by laminating a polarizing plate and a coating retardation layer having anisotropic refractive index, the coating phase is formed on the surface of the transparent resin film of the polarizing plate via a primer layer. Poor layer, by laminating it on the polarizing plate on the side of the transparent resin film, and laminating the transparent protective film on the other side of the polarizing plate simultaneously, can make a composite polarizing plate thinner than before, so as to complete the present invention. Furthermore, at the same time, it was found that by using a transparent resin film as a retardation plate, and laminating the retardation plate on the side of the polarizer without a transparent protective film through an adhesive layer, it is possible to manufacture a composite polarizing plate thinner than before. , so as to complete the present invention.

Accordingly, an object of the present invention is to provide a composite polarizing plate thinner than conventional products while maintaining the same optical performance as conventional products, and a method for producing the same. Another object of the present invention is to provide a thinner composite optical member in which an optical layer exhibiting other optical functions is laminated on the composite polarizing plate. Furthermore, another object of the present invention is to provide a liquid crystal display device capable of further thinning using these composite polarizing plates or composite optical members.

If the present invention is utilized, it is possible to provide a coating phase in which a transparent protective film is attached to one side of a polarizer, and a transparent resin film, a primer layer, and an organically modified clay complex and a binder resin are sequentially formed on the other side. Composite polarizing plate with poor layer.

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

The undercoat layer forming process of providing an undercoat layer on the surface of the transparent resin film,

Coating retardation layer forming process of coating the surface of the undercoat layer with a coating liquid containing an organically modified clay composite and a binder resin in an organic solvent, and removing the solvent therefrom to form a coating retardation layer ,and

In addition, a polarizer and a transparent protective film are prepared, and the transparent protective film is bonded to one side of the polarizer through an adhesive, and the other side of the polarizer is bonded with the transparent resin film side to form the coated retardation layer. Lamination process of transparent resin film.

In addition, according to the present invention, it is also possible to provide a composite optical member in which an optical layer exhibiting other optical functions is laminated on the above-mentioned composite polarizing plate.

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

Description of drawings

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a composite polarizing plate in the present invention.

2 is a schematic cross-sectional view showing an example of a method of manufacturing a composite polarizing plate by steps or using members.

Fig. 3 is a schematic cross-sectional view showing an example of a case where a composite polarizing plate is produced in a roll shape.

4 is a schematic cross-sectional view showing an example of a layer structure of a composite optical member.

5 is a schematic cross-sectional view showing the layer structure of a composite polarizing plate produced in Comparative Example 1. FIG.

6 is a schematic cross-sectional view showing an example of a layer structure of a composite polarizing plate in another embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view showing an example of the method of manufacturing the composite polarizing plate shown in FIG. 6 by steps or using members.

Fig. 8 is a schematic cross-sectional view showing an example of the case where the composite polarizing plate shown in Fig. 6 is produced in a roll shape.

9 is a schematic cross-sectional view showing an example of a layer structure of a composite optical member using the composite polarizing plate shown in FIG. 6 .

10 is a schematic cross-sectional view showing the layer structure of a composite polarizing plate produced in Comparative Example 2. FIG.

In the figure, 10—composite polarizing plate, 11—polarizer, 12—transparent protective film, 13—transparent resin film, 14—undercoat layer, 15—coated retardation layer, 18—adhesive layer, 19—tape Adhesive film, 21—transparent resin film with undercoat layer, 23—transparent resin film with retardation layer applied, 30—transparent resin film conveying roller, 31—undercoat coating machine, 33—bottom Coating drying belt, 36—coating layer coating machine, 38—coating layer drying belt, 40—winding roller, 50—transparent protective film conveying roller, 51, 52—adhesive coating machine, 53, 54—sticking Combining roll, 55—polarizing plate drying belt, 57—film conveying roll with adhesive, 60—product roll, 70—composite optical member, 71—optical layer showing other optical functions, 72—adhesive layer, 80 —composite polarizing plate of comparative example 1, 81—polarizing plate, 82—triacetyl cellulose film, 83—polarizing plate, 84—adhesive layer, 85—coating retardation layer, 88—adhesive layer, 113 —adhesive layer, 114—film with adhesive, 115—retardation plate composed of transparent resin, 116—undercoat layer, 121—polarizing plate, 122—retardation plate with undercoat layer, 123—stack retardation Plate, 124—laminated retardation plate with adhesive layer, 130—retardation plate conveying roller, 140—film conveying roller with adhesive layer, 144—film conveying roller with adhesive, 146—release film roll Winding roller, 150—polarizing plate conveying roller, 180—composite polarizing plate of comparative example 2, 185—retardation plate, 186—undercoating layer.

Detailed ways

Embodiments of the present invention will be described in detail below with reference to the drawings as appropriate. FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a composite polarizing plate in the present invention. In the present invention, a transparent protective film 12 is bonded to one side of the polarizer 11 , and a transparent resin film 13 , a primer layer 14 , and a retardation layer 15 are sequentially formed on the other side to form a composite polarizing plate 10 . An adhesive layer 18 for bonding to a liquid crystal cell or the like may be provided on the outside of the applied retardation layer 15 .

The polarizing plate 11 may be a polarizing film made of a conventionally known polyvinyl alcohol-based resin. Specifically, a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film, or a polyolefin-based oriented film obtained by partially dehydrating a polyvinyl alcohol-based resin, and the like are exemplified. Among them, it is preferable to use a polarizing film obtained by adsorbing and aligning a dichroic dye on a polyvinyl alcohol-based resin film. Either an iodine-based polarizing film using iodine as a dichroic dye or a dye-based polarizing film using a dichroic organic dye as a dichroic dye can be used. The thickness of the polarizing plate 11 is, for example, about 10 to 50 μm. The polyvinyl alcohol-based resin constituting the polarizer 11 may be, for example, polyvinyl butyral or polyvinyl vinyl alcohol obtained by modifying polyvinyl alcohol with aldehydes, in addition to polyvinyl alcohol which is a saponified product of polyvinyl acetate. Acetal, polyvinyl formal or saponified poly(ethylene-vinyl acetate) copolymer, etc.

The transparent protective film 12 and the transparent resin film 13 bonded on both sides of the polarizing plate 11 need only be films commonly known as protective films for polarizing plates. For example, triacetyl cellulose, diacetyl cellulose, butyl acetate Films composed of cellulose-based resins such as acid cellulose, films composed of polyolefin-based resins that are polymers mainly composed of olefins such as propylene or ethylene, and films composed of polyolefin-based resins such as norbornene Films composed of cyclic polyolefin-based resins composed of cyclic cyclic olefins as the main monomer polymers, films composed of polyesters such as polyethylene terephthalate, and polyethersulfone , acrylic resin, polyurethane, polycarbonate, polysulfone, polyether, polymethylpentene, polyether ketone, (meth)acrylonitrile and other films. Among them, preferably, a film composed of a cellulose-based resin or a film composed of a polyolefin-based resin is used. Among cellulose-based resin films, a triacetyl cellulose film is one of preferable films because it has excellent optical transparency and also serves as an effective protective layer when laminated with a polarizing plate.

The transparent resin film 13 can also be used as a resin phase difference plate 115 ( FIG. 6 ) with a phase difference function. The resin retardation plate 115 is composed of a transparent resin, usually a film oriented in-plane. The resin used therein should only be an excellent and uniform resin, and it is preferable to use a stretched film of a transparent thermoplastic resin from the viewpoint of easiness of producing an oriented film. Specific examples of thermoplastic resins include polycarbonates, polyarylates, polysulfones, polyethersulfones, cellulose-based resins, and polymers mainly composed of olefins such as propylene or ethylene. Polyolefin-based resins, cyclic polyolefin-based resins that are polymers of polycyclic cyclic olefins such as norbornene as main monomers, and the like. In addition, a member obtained by providing a coating layer composed of a liquid crystal substance or the like on a transparent resin substrate such as a cellulose-based resin to develop a retardation can also be used as the resin retardation plate 115 .

The in-plane retardation value of the resin retardation plate 115 may be appropriately selected from the range of about 30 to 300 nm according to the application 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 mobile information terminal, it is advantageous that the resin retardation plate 115 is a 1/4 wave resisting plate.

The thicknesses of the transparent protective film 12 and the transparent resin film 13 are, for example, about 10 to 200 μm, respectively. In addition, various surface treatment layers such as an antireflection layer and an antiglare layer may be provided on the surface of the transparent protective film 12 .

When at least one of the transparent protective film 12 and the transparent resin film 13 is composed of a cellulose-based resin such as triacetyl cellulose, it is preferable that the surface of the transparent protective film 12 bonded to the polarizing plate 11 or the formation of the transparent resin film 13 The surface with the primer layer 14 and the surface bonded to the polarizing plate 11 are subjected to saponification treatment. Saponification treatment is usually carried out by immersion in an aqueous alkali solution.

On the surface of the transparent resin film 13, an undercoat layer 14 and an applied retardation layer 15 are sequentially formed. It is advantageous to compose the undercoat layer 14 with a transparent resin formed by coating. The undercoat layer generally refers to an undercoat layer, but the undercoat layer 14 in the present invention functions as an undercoat layer for the retardation layer 15 formed by coating. In addition, due to the existence of the undercoat layer 14, when the coating liquid for coating the retardation layer 15 is applied, the influence of the organic solvent in the coating liquid on the transparent resin film 13 can be prevented. The undercoat layer 14 is composed of a resin that does not exhibit elasticity of an adhesive or the like. The type of the resin is not particularly limited, but it is preferably one excellent in applicability, especially in transparency and adhesion after layer formation.

The resin constituting the undercoat layer 14 may be used in a state of being dissolved in a solvent, and may be used after being diluted with a solvent in order to adjust the film thickness, although it itself has layer-forming ability. 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, ethyl acetate, and isobutyl acetate can be used. Esters such as esters, chlorinated hydrocarbons such as methylene chloride, trichloroethylene, and chloroform, alcohols such as ethanol, 1-propanol, 2-propanol, and 1-butanol, and other common organic solvents . In addition, water can be used as a solvent as long as it is a water-soluble resin.

Preferable examples of the resin constituting the undercoat layer 14 include epoxy resins. As the epoxy resin, either one-component curing type or two-component curing type epoxy resin can be used. In addition, water-soluble epoxy resins are particularly preferred. Examples of water-soluble epoxy resins include polyalkylene polyamines such as diethylenetriamine and triethylenetetramine reacted with dicarboxylic acids such as adipic acid. Amidopolyamine, a polyamide epoxy resin obtained by reacting with epichlorohydrin. As a commercially available product of such a polyamide epoxy resin, there are "Sumire-zuregin 650 (30)" and "Sumire-zuregin 675" (both are commercial products) sold by Sumika Chemtex Co., Ltd. name), etc.

When a water-soluble epoxy resin is used as the resin forming the undercoat layer 14 , it is preferable to mix other water-soluble resins such as polyvinyl alcohol-based resins in order to further improve coatability. In addition to partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, polyvinyl alcohol-based resins can also be carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, methylol-modified polyvinyl alcohol, amino-modified Modified polyvinyl alcohol-based resins such as polyvinyl alcohol. As commercially available products of suitable polyvinyl alcohol-based resins, there is "KL-318" (trade name) of anionic group-containing polyvinyl alcohol sold by Kuraray Co., Ltd., and the like.

When forming the undercoat layer 14 with a coating solution containing a water-soluble epoxy resin, the epoxy resin preferably has a concentration in the range of about 0.2 to 1.5 parts by weight per 100 parts by weight of water. In addition, when a polyvinyl alcohol-based resin is blended into the coating liquid, the amount thereof is preferably about 1 to 6 parts by weight per 100 parts by weight of water. The thickness of the undercoat layer 14 is preferably in the range of 0.1 to 10 μm.

When forming the undercoat layer, there is no particular limitation on the coating method used, and direct gravure printing (direct gravure) method, reverse gravure printing (reverse gravure) method, metal die coating (die coat) method, Various known coating methods such as a knife coating (comma coat) method and a bar coating (bar coat) method.

The coating retardation layer 15 is formed on the undercoat layer 14 . The applied retardation layer 15 is a layer formed by applying a coating solution containing an organic-modified clay composite and a binder resin in an organic solvent, and removing the solvent therefrom.

Among them, the organically modified clay composite is a composite of an organic substance and a clay mineral. Specifically, for example, it may be a composite of a clay mineral having a layered structure and an organic compound, and may be dispersed in an organic solvent. Examples of clay minerals having a layered structure include smectite group, swelling mica, and the like, and their cation exchange ability can be used to achieve composite formation with organic compounds. Among them, the smectite group can be preferably used because it is also excellent in transparency. Examples of clay minerals belonging to the smectite group include hectorite, montmorillonite, and bentonite. Among them, chemically synthesized clay minerals are preferred because they have few impurities and are excellent in transparency. In particular, synthetic hectorite whose particle diameter is controlled to a small value can be preferably used because it suppresses scattering of visible light.

Examples of organic compounds that can be composited with clay minerals include compounds that can react with oxygen atoms or hydroxyl groups of clay minerals, or ionic compounds that can exchange with exchangeable cations. As long as the organically modified clay composite can be swollen or It is not particularly limited as long as it is dispersed in an organic solvent, and specific examples thereof include nitrogen-containing compounds and the like. Examples of nitrogen-containing compounds include primary amines, secondary amines, tertiary amines, quaternary ammonium compounds, and the like. Among them, quaternary ammonium compounds are preferably used in view of easiness of cation exchange and the like.

The organically modified clay complex may be used in combination of two or more. Suitable organically modified clay complexes are commercially available from CO-OP CHEMICA Co., Ltd. under the trade names of "Rosentite (ル-センタイト) STN" or "Rosentite SPN", respectively. Complexes of destoned and quaternary ammonium compounds, etc.

Such an organic-modified clay composite dispersible in an organic solvent can be used in combination with a binder resin from the viewpoint of easiness of application to the primer layer 14 , development of optical properties, mechanical properties, and the like. The binder resin used together with the organically modified clay composite can preferably be a binder resin dissolved in organic solvents such as toluene, xylene, acetone, ethyl acetate, etc., and it is especially preferable to use a binder resin with a glass transition temperature below room temperature (about 20° C. or less). ) of the binder resin. Moreover, it is preferable to have hydrophobicity in order to obtain favorable heat-and-moisture resistance and handleability required when it is applied to a liquid crystal display device. Such preferable binder resins include aldehyde-modified polyvinyl alcohol-based resins such as polyvinyl butyral, polyvinyl formal, and polyvinyl acetal, cellulose acetate butyrate, and the like. Cellulose-based resins, acrylic resins such as butyl acrylate, polyurethane resins, methacrylic resins, epoxy resins, polyester resins, and the like.

Examples of commercially available suitable binder resins include aldehyde-modified resins of polyvinyl alcohol sold by Denki Kagaku Kogyo Co., Ltd. Acrylic resin sold under the trade name "Aron S1601" from Toagosei Co., Ltd., and "SBU ラツカ-0866" from Sumika Bayer Urethane Co., Ltd. Polyurethane resin with isophorone diisocyanate base, etc.

In order to improve the mechanical properties of the coated retardation layer 15 composed of an organic modified clay composite and a binder resin to prevent cracking, the ratio of the organic modified clay composite and the binder resin that can be dispersed in an organic solvent is greater than the former : The weight ratio of the latter is preferably in the range of 1:2 to 10:1, particularly preferably in the range of 1:1 to 2:1.

The organically modified clay composite and the binder resin are coated on the undercoat layer 14 in a state of being contained in an organic solvent. At this time, usually, the binder resin is dissolved in the organic solvent, and the organic-modified clay composite is dispersed in the organic solvent. The solid content concentration of the dispersion liquid is not limited as long as the prepared dispersion liquid is within a practically acceptable range and does not gel or become cloudy. Usually, it is within the total amount of the organically modified clay composite and the binder resin. The solid content concentration is used within a range of about 3 to 15% by weight. The optimum solid content concentration differs depending on the type of the organically modified clay composite and the binder resin or the composition ratio of the two, so it is set for each composition. In addition, various additives such as a viscosity modifier for improving applicability during film formation and a crosslinking agent for further improving hydrophobicity and/or durability may be added.

The coating solution for forming the coating retardation layer 15 containing the organically modified clay composite and the binder resin in an organic solvent preferably has a chlorine content of 2,000 ppm or less. Chlorine-containing compounds are often mixed into the organic-modified clay composite as impurities due to raw materials used in the production of the organic-modified clay composite. If it is used when the amount of such a chlorine compound is large, it may bleed out after it becomes the retardation layer 15 by coating. In this case, when this composite polarizing plate is bonded to the liquid crystal cell glass through the adhesive layer, the adhesive force will fall significantly over time. Therefore, it is preferable to remove chlorine compounds from the organic-modified clay composite by washing, and if the chlorine content therein is 2,000 ppm or less, such a decrease in adhesive force can be suppressed. Chlorine compounds can be removed by washing the organically modified clay complex with water.

In addition, the coating liquid for coating the retardation layer preferably has a moisture content in the range of 0.15 to 0.35% by weight as measured by a Karl Fischer moisture meter. If the water content exceeds 0.35% by weight, phase separation occurs in the water-insoluble organic solvent and the coating liquid tends to separate into two layers. On the contrary, when the water content is less than 0.15% by weight, the haze value tends to increase when it becomes a coated retardation layer. Moisture determination methods include drying method, Karl Fischer method, dielectric constant method, etc. Here, Karl Fischer's method, which is simple and can measure trace units, is used.

There is no particular limitation on the method of adjusting the water content of the coating liquid for coating the retardation layer to the above-mentioned range, and the method of adding water to the coating liquid is convenient and therefore preferred. If only the organic solvent, the organic-modified clay composite, and the binder resin used in the present invention are mixed by a usual method, the moisture content of 0.15% by weight or more hardly appears. Therefore, it is preferable to bring the water content into the above-mentioned range by adding a small amount of water to the coating liquid in which the organic solvent, the organic-modified clay composite, and the binder resin are mixed. The method of adding water can be added at any time during the preparation process of the coating liquid. It is effective and not particularly limited. However, it is preferably used during the preparation of the coating liquid from the point of view that the water content can be controlled with good reproducibility and precision. A method of taking a sample after a certain period of time in the process, measuring the water content, and then adding a specified amount of water. However, the amount of water to be added also includes the case where it does not match the result measured by the Karl Fischer moisture meter. The reason for this is considered to be that water partially interacts (for example, adsorbs) with the organic-modified clay complex. Among them, as long as 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 obtained coating retardation layer can be suppressed to a low value.

The coating method used in forming the coating phase difference layer 15 is not particularly limited, and direct gravure printing (direct gravure) method, reverse gravure printing (reverse gravure) method, metal type coating (die coat) can be used. Various known coating methods such as the doctor blade coating method, the comma coating method, and the bar coating method.

The refractive index anisotropy in the thickness direction of the retardation layer 15 is expressed by the retardation value Rth in the thickness direction defined by the above-mentioned formula (II), and this value can be inclined from the slow axis in the plane by 40 Calculate the phase difference value R40 measured by degrees and the phase difference value R0 in the plane. That is, the retardation value Rth in the thickness direction using the formula (II) can be obtained by using the retardation value R0 in the plane, the retardation value R40 measured by using the slow axis as the inclined axis to make it inclined 40 degrees, the thickness d of the film, and The average refractive index n0 of the film is calculated by numerically obtaining nx, ny, and nz from the following formulas (III) to (V), and substituting them into the formula (II).

R0＝(nx—ny)×d (III)

(nx+ny+nz)/3=n0 (V)

in,

The retardation value Rth in the thickness direction of the retardation layer 15 is preferably appropriately selected from a range of about 40 to 300 nm in accordance with the use of the retardation layer, especially the characteristics of the liquid crystal cell. The retardation value Rth in the thickness direction is preferably not less than 50 nm and not more than 200 nm.

What is necessary is just to join between the polarizing plate 11 and the transparent protective film 12 or between the polarizing plate 11 and the transparent resin film 13 via an adhesive layer. The adhesive used for the adhesive layer should just be transparent. As a preferable example of an adhesive agent, the aqueous solution of the polyvinyl-alcohol-type resin commonly used in this field is mentioned. As the polyvinyl alcohol-based resin, the same polyvinyl alcohol-based resins as those mentioned above in the description of the undercoat layer 14 can be exemplified. An aqueous solution containing a water-soluble epoxy resin and a polyvinyl alcohol-based resin shown above as an example of a coating liquid for forming the undercoat layer 14 may also be used as the adhesive here.

In addition, when bonding the resin phase difference plate 115 and the polarizing plate 11, they may be bonded via the adhesive layer 18 as an adhesive layer. The adhesive layer 18 is also called a pressure-sensitive adhesive, and may be composed of an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether, or the like as a base polymer. Among them, it is preferable to use an acrylic adhesive that has excellent optical transparency, maintains moderate wettability or cohesive force, is also excellent in adhesiveness to the substrate, and has weather resistance or heat resistance. Adhesives that do not cause peeling problems such as floating or peeling under the condition of heating or humidification. In the acrylic adhesive, it is preferable to combine an alkyl ester of acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group or an ethyl group or a butyl group with (meth)acrylic acid or hydroxyethyl (meth)acrylate. Functional group-containing acrylic monomers of equal composition are blended so that the glass transition temperature is 25° C. or lower, more preferably 0° C. or lower, and such an acrylic copolymer having a weight average molecular weight of 100,000 or more can be used as a matrix polymer.

The adhesive layer 18 can be formed by applying and drying an adhesive solution mainly composed of the matrix polymer as described above, or by preparing a release treatment on a film that has been subjected to a release treatment. A film (adhesive-attached film) formed by forming an adhesive layer on its surface is formed by bonding it to the surface on which the retardation layer 15 is applied on the adhesive layer side.

The pressure-sensitive adhesive layer 18 formed as necessary on the applied retardation layer 15 is also the same as above.

Next, a method for producing a composite polarizing plate according to the present invention will be described. As described above, the composite polarizing plate of the present invention can be produced through the following steps.

In the surface of the transparent resin film 13, an undercoat layer forming process in which an undercoat layer 14 is provided,

A coating liquid containing an organically modified clay composite and a binder resin in an organic solvent is coated on the surface of the undercoat layer 14, and the solvent is removed therefrom to form a coated retardation layer 15. forming process, and

In addition, polarizer 11 and transparent protective film 12 are prepared, and the transparent protective film 12 is pasted on one side of the polarizer 11 through the adhesive agent, and the other side of the polarizer 11 is pasted with the transparent resin film 13 side to form the above-described A bonding process of the transparent resin film 13 coated with the retardation layer 15 .

Thereafter, an adhesive layer 18 for bonding to a liquid crystal cell or the like may be provided on the outside of the applied retardation layer 15 . In the case where the adhesive layer 18 is provided on the outside of the applied retardation layer 15, the adhesive layer 18 can be provided after the above steps such as the last or all steps of the applied retardation layer forming step are completed to manufacture a composite polarizing plate. Agent layer 18.

FIG. 2 shows an example of this manufacturing method in a schematic cross-sectional view for each process or using a member. First, in the undercoat layer forming step, as shown in FIG. 2(A), the undercoat layer 14 is formed on the surface of the transparent resin film 13 to form an undercoat-coated transparent resin film 21 . At this time, the surface of the transparent resin film 13 is preferably saponified with an aqueous alkali solution. Then, in the coating retardation layer forming step, as shown in FIG. 2(B), the coating retardation layer 15 is formed on the surface of the undercoat layer 14 to form a transparent resin film 23 with a coating retardation layer. Next, in the bonding process, prepare the polarizing plate 11 shown in FIG. 2(C) and the transparent protective film 12 shown in FIG. 2(D), as shown in FIG. A transparent protective film 12 is bonded to one side of the sheet 11, and a transparent resin film 13 side with a transparent resin film 23 coated with a retardation layer is bonded to the other side to form a composite polarizing plate 10. Furthermore, as shown in FIG. 2(F), an adhesive layer 18 may be formed on the outside of the applied retardation layer 15 as needed.

FIG. 3 is a schematic cross-sectional view showing an example of producing a roll-shaped composite polarizing plate by this method. In this example, first, by the primer coating machine 31, on the surface of the transparent resin film 13 extracted from the transparent resin film conveying roller 30, coat the coating liquid for the primer, and then pass the primer drying belt. 33 to make it dry, and then provide to the formation of the coated retardation layer. That is, the coating liquid for the phase difference layer is coated on the surface of the undercoat layer of the transparent resin film 21 [refer to FIG. The layer drier 38 dries it to obtain a transparent resin film 23 with a retardation layer applied thereto [see FIG. 2(B)]. In this state, it passes through the winding roll 40 and is then provided to be bonded to a polarizing plate.

In the pasting process, the transparent protective film 12 drawn out from the conveying roller 50 is pasted on one side of the polarizing plate 11 sent from the polarizing plate manufacturing line not shown, and then pasted on the other side of the polarizing plate 11. The transparent resin film side (opposite side to which the retardation layer is applied) of the transparent resin film 23 with the retardation layer applied behind the winding roll 40 of the present invention. Before lamination, an adhesive is applied to the surface of the transparent protective film 12 and the transparent resin film side surface of the transparent resin film 23 coated with a retardation layer by the adhesive coating machines 51 and 52 respectively. Next, both surfaces of the polarizing plate 11 are sandwiched between the transparent protective film 12 and the transparent resin film 23 with a retardation layer applied thereto, and are bonded by the bonding rollers 53 and 54 . Next, the polarizing plate drying belt 55 is used to dry it, and then the film 19 with an adhesive (a film in which an adhesive layer is provided on a release film as described above) drawn out from the conveying roller 57 is bonded to it. The mixture layer side is bonded to the coated retardation layer to form a composite polarizing plate 10 with an adhesive, which is wound up on a product roll 60 .

Fig. 3 shows an example in which a continuous production line is used to obtain a composite polarizing plate with an adhesive, but the production line may be divided into appropriate numbers as necessary. For example, the transparent resin film 23 with a coated retardation layer formed by sequentially forming a primer layer and a coated retardation layer on a transparent resin film may be temporarily wound up on a roll. In addition, for example, the undercoated transparent resin film 21 may be temporarily wound on a roll at the stage where the undercoat layer is formed on the transparent resin film until the transparent resin film 23 coated with a retardation layer is obtained. superior. Furthermore, the composite polarizing plate before the adhesive layer is provided is temporarily wound on a roll, and then the adhesive layer is provided in another process.

In addition, in FIG. 3 , curved arrows indicate the rotation direction of the rollers. In addition, although the adhesive layer shows the form which bonded the adhesive-coated film 20 on the adhesive layer side, you may provide an adhesive layer by the method of applying an adhesive coating liquid.

In addition, FIG. 7 shows that in the case where the transparent resin film is used as a resin retardation plate, the manufacturing method is divided into each step by taking the case where the adhesive layer 18 is provided at the end of the application retardation layer forming step as an example. Or use a cross-sectional pattern diagram of the member. First, in the undercoat layer forming step, as shown in FIG. 7(A), the undercoat layer 116 is formed on the surface of the resin retardation film 115 to form the undercoat layer 122 . At this time, the resin retardation plate 115 is preferably subjected to corona discharge treatment on both surfaces thereof. Next, in the coating phase difference layer forming step, as shown in FIG. Thereafter, as shown in FIG. 7(C), an adhesive layer 18 is formed on the surface on which the retardation layer 15 is applied, thereby forming a laminated retardation film 124 with an adhesive layer. Furthermore, in the pasting process, prepare the polarizing plate 121 shown in FIG. 7(D) and stick the transparent protective film 12 on one side of the polarizing plate 11. The retardation film 115 side of the laminated retardation film 124 with an adhesive layer (in the case where the adhesive layer 18 is not provided, the laminated retardation film 123) and the polarizing plate 11 side of the polarizing plate 121 are joined together to form Composite polarizing plate 10.

FIG. 8 is a schematic cross-sectional view showing an example of the case where a roll-shaped composite polarizing plate is manufactured in this way.

In this example, first, the surface of the phase difference plate 115 extracted from the phase difference plate conveying roller 30 is coated with the coating liquid for the undercoat layer by the undercoat layer coating machine 31, and then passed through the undercoat layer drying belt. 33 to make it dry, and then provide to the formation of the coated retardation layer. In this case, it is also preferable that the retardation plate 115 is subjected to corona discharge treatment on both surfaces thereof. Next, by the coating layer coating machine 36, on the surface of the undercoat layer of the phase difference plate 122 [referring to FIG. The layer dryer 38 dries it to form a laminated phase difference plate 123 [see FIG. 7(B)]. Then, this laminated phase difference plate 123 is provided for lamination with the adhesive film 19 . The adhesive-attached film 19 described here is a film formed by providing an adhesive layer on a release film. On the coated phase difference layer of the laminated phase difference plate 123, the adhesive layer side is bonded from the side of the adhesive layer. The adhesive-attached film 19 fed out by the adhesive-attached film feed roller 140 is supplied in this manner and bonded together to obtain the laminated retardation film 124 with an adhesive layer. After passing through the winding roll 40 in this state, bonding to a polarizing plate is provided.

In the pasting process, first, an adhesive layer is applied to the polarizing plate side of the polarizing plate 121 drawn out from the conveying roller 150 (as described with reference to FIG. The adhesive-attached film 114 drawn out from the other transport roller 144 is side-bonded, whereby the adhesive is bonded to the polarizing plate. The adhesive-attached film 114 described here is a film in which the adhesive layer 13 described above with reference to FIG. 6 is provided on a release film. The adhesive layer is adhered to the polarizing plate of the polarizing plate 121 , and the release film is peeled off, and wound up on the release film take-up roll 146 . Next, using the bonding rollers 53 and 54, the polarizing plate 121 with the adhesive layer formed thereon is bonded to the resin retardation plate side of the laminated retardation film 124 with an adhesive layer after passing through the winding roller 40 described above. On the side of the adhesive layer, the composite polarizing plate 10 to be a product is obtained. The composite polarizing plate 10 is then wound onto a product roll 60 .

FIG. 8 shows an example in which a continuous production line is used until the composite polarizing plate 10 with an adhesive is obtained, but the production line may be divided into appropriate numbers as necessary. For example, the laminated retardation film 123 in which an undercoat layer and a retardation layer are applied sequentially on the retardation film 115, or a tape bonding in which an adhesive layer is formed on the retardation layer-applied side can be used. The step of laminating the phase difference plate 124 of the agent layer is temporarily wound up on a roll. In addition, for example, the undercoated retardation film 122 formed by forming an undercoat layer on the retardation film 115 may be temporarily wound on a roll until the laminated retardation film 123 is obtained.

In addition, in FIG. 8 , curved arrows indicate the rotation direction of the rollers. In addition, the adhesive layer or adhesive layer shown is formed by bonding the adhesive-coated film 19 or the adhesive-coated film 114 on the side of the adhesive layer or the side of the adhesive layer. Method of Adhesive Application Liquid or Adhesive Application Liquid An adhesive layer or an adhesive layer is provided.

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. 4 and 9 are schematic cross-sectional views showing examples of the layer structure of the composite optical member.

In this example, an optical layer 71 exhibiting other optical functions is laminated on the transparent protective film 12 side of the composite polarizing plate 10 shown in FIG. 1 or FIG. 6 to form a composite optical member 70 . Both can be laminated using, for example, an adhesive, which is shown as adhesive layer 72 in FIGS. 4 and 9 . As the optical layer 71 exhibiting other optical functions, for example, optical layers conventionally used in formation of liquid crystal display devices, such as a brightness improvement film, are mentioned. The brightness improving film refers to an optical film that can improve the utilization efficiency of backlight light in a liquid crystal display device. As the brightness improving film, for example, "DBEF" sold as a reflective polarized light separation film sold by Minnesota Mining and Manufacturing Company (3M Company) [Sumitomo 3M Co., Ltd. in Japan], and "DBEF" sold also from 3M Company "BEF" of the upward prism sheet, etc. When bonding the other optical layer 71 with an adhesive, the same adhesive as that described above for the adhesive layer 18 in the same figure with reference to FIG. 1 can be used.

In addition, in the composite polarizing plate 10 shown in FIG. 1 , a layer exhibiting other optical functions such as a positive unidirectional or bidirectional retardation plate may be arranged outside the adhesive layer 18 . In this case, an adhesive layer is usually further provided on the outside. For example, the adhesive layer is laminated on the outside of the adhesive layer 18 of the composite polarizing plate 10 shown in FIG. 1 on the premise that the adhesive layer is on the outside. A retardation plate with an adhesive layer is sufficient.

The composite polarizing plate 10 shown in FIG. 1 or FIG. 6 or the composite optical member 70 shown in FIG. 4 or FIG. 9 can be disposed on at least one side of the liquid crystal cell to form a liquid crystal display device. Composite polarizing plates 10 may also be arranged on both surfaces of the liquid crystal cell. In addition, the composite polarizing plate 10 may be arranged on one surface of the liquid crystal cell, and the composite optical member 70 may be arranged on the other surface. The composite polarizing plate 10 or the composite optical member 70 may be arranged on one side of the liquid crystal cell, and another polarizing plate may be arranged on the other side of the liquid crystal cell with a retardation plate as necessary. As mentioned in the item of background technology, the liquid crystal cell is preferably in vertical alignment (VA) mode, but in addition, the composite polarizing plate or composite optical member of the present invention can also be used for liquid crystals in other modes such as bent (bent) alignment (ECB) mode. The unit functions effectively.

Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these examples. In the examples, % and parts indicating content or usage amount are weight standards unless otherwise specified. The compositions of the coating liquid for the undercoat layer and the coating liquid for the retardation layer used in the following examples are as follows.

[Coating liquid for undercoating]

As the water-soluble epoxy resin, "Sumi Razor 650 (30)" (trade name, aqueous solution with a solid content concentration of 30%) manufactured by Sumika Chemtex Co., Ltd., which is a polyamide epoxy resin, was used. As the polyvinyl alcohol-based resin, "KL-318" (trade name) which is an anionic group-containing polyvinyl alcohol manufactured by Kuraray Co., Ltd. was used, and a coating solution was formulated with the following composition.

Composition of the coating solution for the undercoat layer:

Water 100 parts

Polyamide epoxy resin "Sumire—ズレジン) 650 (30)" 1.5 parts

Anionic group-containing polyvinyl alcohol "KL-318" 3 parts

The coating solution was mixed and stirred with polyvinyl alcohol "KL-318" while heating water to 100°C, cooled to room temperature, and then mixed with polyamide epoxy resin "Sumire-zuresin" 650 (30)" mixing, stirring, and thus prepared. The coating liquid prepared here can also be used as an adhesive agent for a transparent protective film and a polarizing plate, or a transparent resin film and a polarizing plate.

[Coating solution for retardation layer]

As the organically modified clay complex, "Rosentate STN" (trade name) manufactured by CO-OP CHEMICA Co., Ltd., which is a complex of synthetic hectorite and trioctylmethylammonium ion, was used. In addition, As the binder resin, "SBU ラツカ" manufactured by Sumika Bayer Polyurethane Co., Ltd. was used, which is a polyurethane resin using isophorone diisocyanate as a base and a resin varnish with a solid content concentration of 30%. —) 0866" (trade name), a coating solution formulated with the following composition.

Composition of the coating liquid for retardation layer:

Polyurethane resin varnish "SBU Lejia (ラツカ—) 0866" 16.0 parts

Organic modified clay complex "Rusentate STN" 7.2 parts

Toluene 76.8 parts

Water 0.3 parts

The organically modified clay composite used here is obtained in a state where a maker (maker) produces synthetic hectorite before organic modification, acid washes it, organically modifies it, and then washes it with water. The amount of chlorine contained therein was 1,111ppm. In addition, this coating solution was prepared by mixing and stirring the above-mentioned composition, and filtering it through a filter with a pore diameter of 1 μm, and the moisture content measured by a Karl Fischer moisture meter was 0.25%. The solid content weight ratio of the organically modified clay composite/binder resin in this coating liquid was 6/4.

[Example 1]

(a) Formation of retardation layer

On one side of a 40 μm thick transparent resin film composed of saponified triacetyl cellulose, apply the coating solution for the undercoat layer, and dry it at 80° C. for about 1 minute to form a moisture content of about 20%. base coat. Next, the coating liquid for a phase difference layer was coated on the undercoat layer, followed by drying at 90° C. for 3 minutes to form a coating phase difference layer.

(b) Production of polarizers

A polyvinyl alcohol film with an average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more, and a thickness of 75 μm is stretched about 5 times by a dry method, and then immersed in pure water at 60°C while maintaining tension. Then, at 28° C., it was immersed for 60 seconds in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.05/5/100. Thereafter, at 72°C, it was immersed in an aqueous solution having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 for 300 seconds. Next, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. to obtain a polarizing plate in which iodine was adsorbed and aligned in polyvinyl alcohol.

(c) Fabrication of composite polarizing plate

The triacetyl cellulose film/undercoat layer/coating retardation film prepared in (a) are attached to one side of the polarizer obtained in (b) with the triacetyl cellulose film side through the adhesive respectively. A laminated film composed of three layers, and a triacetyl cellulose film on the other side of the polarizer to make a composite polarizing plate. That is, the triacetyl cellulose film side surface of the triacetyl cellulose film side surface of the laminated film composed of the triacetyl cellulose film/undercoat layer/coated retardation layer prepared in (a) and the triacetyl fiber saponified on the surface On the saponification-treated surface of a transparent protective film with a thickness of 40 μm of plain composition, the coating liquid for the undercoat layer is coated respectively, and the polarizer obtained in the above (b) is attached to the side of each coating layer, It was then dried at 80° C. for 7 minutes. Then, an acrylic adhesive ["P-3132" manufactured by Lintec Co., Ltd.] was adhered to the surface on the side where the retardation layer was applied, and a transparent protective film/polarizer/transparent resin film/undercoat layer were laminated in this order. / Composite polarizing plate coated with retardation layer/adhesive layer. The layer structure of the composite polarizing plate produced in this example is shown in FIG. 1 .

(d) Thickness measurement of composite polarizing plate

Cut the composite polarizing plate with an adhesive layer obtained in (c) into a width of 25 mm and a length of about 850 mm, and use a digital length measuring device "MH-15M" manufactured by Nikon Co., Ltd. to measure 9 points in the longitudinal direction thickness of. Table 1 shows the average results at nine points.

(e) Optical performance evaluation of composite polarizing plate

The composite polarizing plate with the adhesive layer obtained in (c) was cut into 25 mm squares, and the adhesive layer side thereof was attached to the soda glass, and then in an autoclave (autoclave) at a pressure of 5 kgf/ cm ² at a temperature of 50°C for 20 minutes, and then, the retardation value in the thickness direction, the degree of polarization, and the haze value were measured by the following method, and the results are shown in Table 1.

(e1) Retardation value in the thickness direction: Measured using a phase difference measuring device "KOBRA-WR" manufactured by Oji Scientific Instruments.

(e2) Degree of polarization: measured using a spectrophotometer "UV-2400" manufactured by Shimadzu Corporation.

(e3) Turbidity value: It measured using the haze meter (haze meter) "HZ-1" manufactured by SUGA Testing Instrument Co., Ltd.

[Comparative example 1]

(a) Fabrication of composite polarizing plate

On the release-treated surface of a polyethylene terephthalate film with a thickness of 38 μm (the water contact angle of the release-treated surface is 110°) that has been subjected to a release treatment, the coating for the retardation layer is applied. solution, and then dried at 90°C for 3 minutes to form a coated retardation layer. Separately prepared polarizing plate "SRW062AP6-HC2" with adhesive manufactured by Sumitomo Chemical Co., Ltd. both sides, and further on the side of the adhesive layer of the polarizing plate with an adhesive layer formed on the other side), the coated retardation layer formed on the polyethylene terephthalate film is bonded, from which The polyethylene terephthalate film was peeled off, and then the same acrylic adhesive used in Example 1 ["P-3132" manufactured by Lintec Co., Ltd. ”] to obtain a composite polarizing plate. A schematic cross-sectional view of the layer structure of the composite polarizing plate obtained in this example is shown in FIG. 5 . That is, this composite polarizing plate 80 is (polarizing plate 83 in which both sides of a polarizing plate 81 are sandwiched between triacetyl cellulose films 82 and 82)/adhesive layer 84/coated retardation layer 85/adhesive layer 88 layer structure.

(b) Thickness measurement of composite polarizing plate

Cut the composite polarizing plate with an adhesive layer obtained in (a) into a width of 25 mm and a length of about 850 mm, and use a digital length measuring device "MH-15M" manufactured by Nikon Co., Ltd. to measure 9 points in the longitudinal direction thickness of. Table 1 shows the average results at nine points.

(c) Optical performance evaluation of composite polarizing plate

Cut the composite polarizing plate with the adhesive layer obtained in (a) into 25 mm squares, stick the adhesive layer side to the soda glass, and then put it in an autoclave at a pressure of 5 kgf/cm ² , At a temperature of 50° C., pressurization was carried out for 20 minutes, and then, the retardation value in the thickness direction, the degree of polarization, and the haze value were measured in the same manner as in (e1) to (e3) of Example 1, and the results are shown in Table 1.

From the above results, it can be seen that satisfying the requirements specified in the present invention in a balanced manner is necessary for realizing the objective optical characteristics of the present invention.

Table 1

[Example 2]

(a) Fabrication of laminated retardation plate

Corona discharge is performed on both sides of a uniaxially stretched norbornene-based resin film, that is, a retardation plate with a thickness of 28 μm ("CSES430120Z-S-KY" manufactured by Sumitomo Chemical Co., Ltd., in-plane retardation value 120nm). deal with. Next, the coating liquid for an undercoat layer was coated on one side, and dried at 80° C. for about 1 minute to form an undercoat layer with a moisture content of about 20%. Next, the coating liquid for a phase difference layer was coated on the undercoat layer, followed by drying at 90° C. for 3 minutes to form a coating phase difference layer. Next, an acrylic adhesive ["P-3132" manufactured by Lintec Co., Ltd.] was adhered to the applied retardation layer to obtain a sequentially laminated resin retardation plate/undercoat layer/applied retardation layer. /Adhesive layer laminated phase difference plate.

(b) Fabrication of composite polarizing plate

In addition, prepare a polarizing plate [Sumitomo Chemical Co., Ltd. "SR066A-HC"] with a transparent protective film composed of triacetyl cellulose attached to one side of the polyvinyl alcohol-iodine polarizing film. Adhesive [Lintec Co., Ltd. "L1"] was coated on the surface of the protective film, and the resin retardation plate side of the laminated retardation plate was bonded thereon to obtain a composite with an adhesive layer. Polarizing plate. The layer structure of the composite polarizing plate produced in this example is shown in FIG. 6 .

(c) Thickness measurement of composite polarizing plate

Cut the composite polarizing plate with an adhesive layer obtained in (b) into a width of 25 mm and a length of about 850 mm, and measure it in the longitudinal direction using a digital length measuring device "MH-15M" manufactured by Nikon Co., Ltd. 9 points of thickness. Table 2 shows the average results at nine points.

(d) Evaluation of the optical properties of the composite polarizing plate

Cut the composite polarizing plate with the adhesive layer produced in (b) into 25 mm squares, attach the adhesive layer side to the soda glass, and then place it in an autoclave at a pressure of 5 kgf/cm ^2. Pressurize for 20 minutes at a temperature of 50° C., then measure the retardation value, polarization degree, and haze value in the thickness direction by the following method, and the results are shown in Table 2.

(d1) Retardation value in the thickness direction: Measured using a phase difference measuring device "KOBRA-WR" manufactured by Oji Scientific Instruments.

(d2) Degree of polarization: measured using a spectrophotometer "UV-2400" manufactured by Shimadzu Corporation.

(d3) Turbidity value: Measured using a haze meter "HZ-1" manufactured by SUGA Testing Instrument Co., Ltd.

[Comparative example 2]

(a) Fabrication of composite polarizing plate

On the resin retardation plate side of the laminated retardation plate prepared in (a) of Example 2, a separately prepared polarizing plate with adhesive "SRW062AP6" manufactured by Sumitomo Chemical Co., Ltd. was bonded to the adhesive layer side. HC2" (a polarizing plate in which an adhesive layer is formed on one side by clamping both sides of a polarizing plate in which orientation iodine has been adsorbed on polyvinyl alcohol is sandwiched by a triacetyl cellulose film with a thickness of 40 μm), and adhesive tape is produced. Composite polarizing plate with agent layer. A schematic cross-sectional view of the layer structure of the composite polarizing plate obtained in this example is shown in FIG. 10 . That is, the composite polarizing plate 180 is composed of triacetyl cellulose film 82/polarizer 81/triacetyl cellulose film 82/adhesive layer 84/resin retardation plate 185/undercoat layer 186/coated retardation layer 85/ Layer structure of the adhesive layer 88 .

(b) Thickness measurement of composite polarizing plate

Cut the composite polarizing plate with an adhesive layer prepared in (a) into a width of 25 mm and a length of about 850 mm, and measure 9 points in the length direction using a digital length measuring device "MH-15M" manufactured by Nikon Co., Ltd. thickness of. Table 2 shows the average results at nine points.

(c) Optical performance evaluation of composite polarizing plate

Cut the composite polarizing plate with an adhesive layer produced in (a) into a 25 mm angle, attach the adhesive layer side to soda glass, and then sterilize in an autoclave at a pressure of 5 kgf/cm ² and a temperature of At 50°C, pressurization was carried out for 20 minutes, and then, the retardation value, polarization degree, and haze value in the thickness direction were measured by the same method as in Example 1 (d1) to (d3), and the results are shown in the table. 2.

Table 2

As can be seen from the comparison between the above examples and comparative examples, the composite polarizing plate of the present invention exhibits the same optical performance as conventional products (comparative examples 1 and 2), and at the same time can be made thinner.

Industrial availability

The composite polarizing plate of the present invention is a composite polarizing plate formed by directly forming an undercoat layer and coating a retardation layer on the transparent resin film, and laminating it and a transparent protective film on both sides of the polarizer. This makes it thinner than previous products. Furthermore, by giving the transparent resin film a retardation function and adhering the polarizing plate with an adhesive layer, a composite polarizing plate thinner than conventional ones can be obtained. Therefore, a liquid crystal display device to which this composite polarizing plate or a composite optical member formed by laminating an optical layer exhibiting other optical functions can be made thinner than conventional ones.

Claims (16)

1. A composite polarizing plate, wherein, A transparent protective film is pasted on one side of the polarizer, and a transparent resin film, a primer layer, and a coated retardation layer containing an organic modified clay complex and an adhesive resin are sequentially formed on the other side. 2. The composite polarizing plate according to claim 1, wherein, The transparent resin film is a resin retardation plate. 3. The composite polarizing plate according to claim 9, wherein, The resin retardation plate is oriented in-plane. 4. The composite polarizing plate according to claim 1 or 2, wherein, The polarizing plate is a polarizing plate in which a dichroic dye is adsorbed and aligned on a polyvinyl alcohol-based resin film. 5. The composite polarizing plate according to claim 1 or 2, wherein, The protective film bonded on one side of the polarizing plate is composed of cellulose-based resin or polyolefin-based resin. 6. The composite polarizing plate according to claim 1, wherein, The transparent resin film on which the primer layer is formed is composed of cellulose-based resin or polyolefin-based resin. 7. The composite polarizing plate according to claim 1 or 2, wherein, The base coat is composed of transparent resin. 8. The composite polarizing plate according to claim 7, wherein, The base coat contains epoxy resin. 9. The composite polarizing plate according to claim 7, wherein, The undercoat layer is formed of a composition containing a water-soluble epoxy resin and a polyvinyl alcohol-based resin. 10. The composite polarizing plate according to claim 9, wherein, The water-soluble epoxy resin is a polyamide epoxy resin. 11. A method for manufacturing a composite polarizing plate, characterized in that, have: The undercoat layer forming process of providing an undercoat layer on the surface of the transparent resin film, Coating retardation layer forming process of coating the surface of the undercoat layer with a coating liquid containing an organically modified clay composite and a binder resin in an organic solvent, and removing the solvent therefrom to form a coating retardation layer ,and In addition, a polarizer and a transparent protective film are prepared, and the transparent protective film is bonded to one side of the polarizer through an adhesive, and the other side of the polarizer is bonded with the transparent resin film side to form the coated retardation layer. Lamination process of transparent resin film. 12. The manufacturing method of composite polarizing plate according to claim 11, wherein, The transparent resin film is a resin retardation plate. 13. The manufacturing method of composite polarizing plate according to claim 12, wherein, The resin retardation plate is oriented in-plane. 14. A composite optical member, wherein, An optical layer exhibiting other optical functions is laminated on the composite polarizing plate according to claim 1 or 2. 15. A liquid crystal display device, wherein, The composite polarizing plate according to claim 1 or 2 is disposed on at least one side of the liquid crystal cell. 16. A liquid crystal display device, characterized in that, The composite optical member according to claim 14 is disposed on at least one surface of the liquid crystal cell.

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