JP2011013684A - Adhesive retardation layer-stuck polarizing plate, optical film and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive retardation layer-stuck polarizing plate capable of suppressing a change in optical characteristics even under heating and humidification conditions and capable of retaining high visibility.SOLUTION: The adhesive retardation layer-stuck polarizing plate (4) is obtained by laminating an acrylic adhesive layer on the retardation layer side of a retardation layer-stuck polarizing plate (3) having a retardation layer on at least one of transparent protective films of a polarizing plate (2) in which the transparent protective films are laminated on both sides of an iodine polarizer (1), wherein the iodine polarizer (1) has a ratio (K/I) of 0.200-0.235, the transparent protective films are laminated on the iodine polarizer (1) with a water-soluble adhesive containing a polyvinyl alcohol resin containing an acetoacetyl group, the retardation layer-stuck polarizing plate (3) has a dimension shrinkage rate of ≤0.5%, and the adhesive retardation layer-stuck polarizing plate (4) has a single transmittance of 41.0-43.2.

Description

  The present invention relates to an adhesive-type retardation layer-attached polarizing plate. The adhesive-type retardation layer-attached polarizing plate is a flat panel such as a liquid crystal display device (hereinafter abbreviated as LCD), an electroluminescence display device (hereinafter abbreviated as ELD) as an optical film in which the polarizing plate with an adhesive phase difference layer is singly or laminated. An image display device such as a display or a PDP can be formed.

  2. Description of the Related Art Conventionally, a polarizing plate used for an LCD generally has a transparent protective film bonded to both sides of a polarizer with an adhesive. As the polarizer, a polyvinyl alcohol polarizer oriented by adsorbing iodine to polyvinyl alcohol and stretching is used, and a transparent protective film using triacetyl cellulose is generally used. Further, since the polarizing plate is laminated on a liquid crystal cell or the like, it is usually used as an adhesive polarizing plate in which an acrylic pressure-sensitive adhesive layer formed with an acrylic pressure-sensitive adhesive is laminated.

  In recent years, high contrast has been demanded with a wide viewing angle. Therefore, by laminating the retardation layer (birefringent layer) on the polarizing plate, the retardation property of the retardation layer is matched with the retardation property at the time of black display of the liquid crystal cell, thereby achieving high contrast with a wide viewing angle. High display quality can be obtained. For example, in order to compensate the oblique viewing angle of TN liquid crystal, a viewing angle can be greatly improved by laminating a retardation layer using a discotic liquid crystal on a polarizing plate.

  On the other hand, in the polarizing plate with a retardation layer in which the retardation layer using the discotic liquid crystal is laminated, the retardation of the retardation layer changes due to the influence of the dimensional shrinkage of the polarizing plate accompanying the environmental change. There is a problem that the visibility is remarkably lowered due to a decrease in contrast or unevenness in black luminance in the surface.

  To solve this problem, the thickness of the base film on which the retardation layer of the discotic liquid crystal is laminated is reduced (Patent Document 1), and a material having a small photoelastic coefficient is used as the base film (Patent Document). 2) Methods such as reducing the thermal expansion coefficient of the cellulose acetate film used as the substrate film (Patent Document 3) and increasing the stress relaxation property of the pressure-sensitive adhesive layer (Patent Document 4) have been proposed. Yes.

  Moreover, as an adhesive between the polarizer and the transparent protective film in the polarizing plate, an adhesive containing a polyvinyl alcohol resin containing an acetoacetyl group and a cross-linking agent such as glyoxal is used to improve the water resistance of the adhesive interface. A method for solving problems such as delamination (end peeling of the transparent protective film from the polarizer) under a high-temperature humidified environment has also been proposed (Patent Document 5).

  However, even if the polarizing plate with the retardation layer is combined with the durability improving technology as described above, the peripheral unevenness due to the depolarization occurs in the peripheral portion of the polarizing plate under the above environment, and the polarizing performance is also improved. It was greatly reduced and the visibility could not be maintained.

  Furthermore, in in-vehicle applications and the like, even in tests assuming extremely harsh environments such as a high temperature of 100 ° C., a high temperature and high humidity of 60 ° C./95% RH, and a thermal shock test that repeats the conditions of −40 ° C. and 80 ° C. There is a need to maintain visibility. However, since an adhesive layer having excellent stress relaxation generally has poor adhesion, it cannot follow the rapid dimensional shrinkage behavior of a polarizing plate in a thermal shock test, resulting in defects in appearance such as peeling and firing.

Japanese Patent Laid-Open No. 2004-163606 JP 2001-100036 A JP 2003-55477 A JP-A-7-198945 Japanese Patent Laying-Open No. 2005-3884

  The present invention relates to a polarizing plate with an adhesive retardation layer obtained by further laminating an adhesive layer on a polarizing plate with a retardation layer, which can suppress changes in optical properties even under heating and humidification conditions, and has visibility. It aims at providing the polarizing plate with an adhesion type phase contrast layer which can be maintained high.

  The present invention also provides the above-mentioned pressure-sensitive adhesive retardation layer-attached polarizing plate, which can satisfy the high durability capable of suppressing defects in appearance even in a thermal shock test. With the goal.

  Another object of the present invention is to provide an optical film using the adhesive-type retardation layer-attached polarizing plate, and further to provide an image display device using the adhesive-type retardation layer-attached polarizing plate or the optical film. And

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by the following polarizing plate with an adhesive retardation layer, and have completed the present invention.

That is, the present invention relates to a polarizing plate with a retardation layer (3) having a retardation layer on at least one transparent protective film of a polarizing plate (2) in which transparent protective films are laminated on both surfaces of an iodine-based polarizer (1). ), And an adhesive type retardation layer-attached polarizing plate (4) in which an acrylic adhesive layer is further laminated on the retardation layer side,
In the iodine polarizer (1), the ratio (K / I) of the content (wt%) of iodine (I) and the content (wt%) of potassium (K) in the polarizer is 0.200 to 0.00. 235,
In the polarizing plate (2), the iodine polarizer (1) and the transparent protective film are laminated by an adhesive layer formed of a water-soluble adhesive containing a polyvinyl alcohol resin containing an acetoacetyl group and a crosslinking agent. And
The retardation layer-attached polarizing plate (3) has a dimensional shrinkage ratio of 0.5% or less represented by the following formula in the absorption axis direction, measured after standing at 80 ° C. for 24 hours.
Dimensional shrinkage (%) = <{(Dimension before leaving) − (Dimension after leaving)} / (Dimension before leaving)> × 100,
The pressure-sensitive adhesive retardation film-attached polarizing plate (4) relates to a pressure-sensitive adhesive retardation film-attached polarizing plate characterized by a single transmittance of 41.0 to 43.2%.

  In the adhesive-type retardation layer-attached polarizing plate, as the retardation layer-attaching polarizing plate (3), a retardation layer is coated by coating a liquid crystal material on a transparent protective film, or separately, a liquid crystal material is used. A retardation layer formed by coating can be disposed on a transparent protective film by transfer, and the transparent protective film and the retardation layer can be integrated.

  In the adhesive-type retardation layer-attached polarizing plate, the retardation layer is preferably one in which an inclined alignment layer of discotic liquid crystal is fixed.

  In the adhesive type retardation layer-attached polarizing plate, the acrylic adhesive layer in the adhesive type retardation layer-attached polarizing plate (4) contains a (meth) acrylic polymer (A) and a crosslinking agent. What was formed by carrying out the crosslinking reaction of the adhesive is suitable.

  In the pressure-sensitive adhesive retardation film-attached polarizing plate, the (meth) acrylic polymer (A) has a hydroxyl group-containing (meth) acrylic monomer (a2) 0. 0 with respect to 100 parts by weight of the alkyl (meth) acrylate (a1). It is preferable to contain 01-5 weight part as a copolymerization component.

  In the pressure-sensitive adhesive retardation film-attached polarizing plate, the acrylic pressure-sensitive adhesive is 0.02 to 2 weight percent of the peroxide (B) as a crosslinking agent with respect to 100 parts by weight of the (meth) acrylic polymer (A). What contains a part can be used.

  In the pressure-sensitive adhesive retardation film-attached polarizing plate, as an acrylic pressure-sensitive adhesive, 0.001 to 2 weight of an isocyanate compound (C) as a crosslinking agent with respect to 100 parts by weight of a (meth) acrylic polymer (A). What contains a part can be used.

  In the pressure-sensitive adhesive retardation film-attached polarizing plate, the acrylic pressure-sensitive adhesive is 0.02 to 2 weight percent of the peroxide (B) as a crosslinking agent with respect to 100 parts by weight of the (meth) acrylic polymer (A). And an isocyanate compound (C) containing 0.001 to 2 parts by weight can be used.

  In the adhesive-type retardation layer-attached polarizing plate, the acrylic adhesive preferably further contains a silane coupling agent.

  In the adhesive-type retardation layer-attached polarizing plate, the acrylic pressure-sensitive adhesive layer can be laminated on the retardation layer via an anchor coat layer.

  The present invention also relates to an optical film characterized in that the pressure-sensitive adhesive retardation film-attached polarizing plate is used.

  Furthermore, the present invention relates to an image display device in which the pressure-sensitive adhesive retardation film-attached polarizing plate or the optical film is used.

  As described above, the polarizing plate with an adhesive type retardation layer of the present invention is disposed on at least one transparent protective film of the polarizing plate (2) in which the transparent protective film is laminated on both surfaces of the iodine-based polarizer (1). The polarizing plate with a retardation layer (4) having a retardation layer and a polarizing plate with a retardation layer (4) obtained by further laminating an acrylic pressure-sensitive adhesive layer on the retardation layer side. Each of 1) to (4) has a specific configuration. By combining such configurations, changes in optical properties can be suppressed even under heating and humidification conditions, and the adhesive type can maintain high visibility. A polarizing plate with a retardation layer is obtained. For example, delamination, warpage, shift in compensation state due to phase difference change, polarization function deterioration, coloring, black luminance unevenness, and peripheral unevenness due to depolarization of peripheral portions can be suppressed, and visibility can be maintained.

  In the iodine polarizer (1), the ratio (K / I) of the content (wt%) of iodine (I) and the content (wt%) of potassium (K) in the polarizer is 0.200 to 0.00. 235. By setting the ratio (K / I) within the above range, the coloring of the polarizer is suppressed, the change in optical properties such as transmittance and polarization degree is small even at high temperature, and the durability is excellent, and the polarization degree is high. can do. When the ratio (K / I) is larger than 0.235, the optical characteristics during high temperature heating are deteriorated, which is not preferable. On the other hand, when the ratio (K / I) is smaller than 0.200, the polarization characteristics are insufficient, which is not preferable for applications requiring high contrast. From this viewpoint, the ratio (K / I) is preferably 0.205 to 0.230, more preferably 0.210 to 0.225. The iodine (I) content (% by weight) and potassium (K) content (% by weight) in the polarizer were determined from the element content analyzed by fluorescent X-ray analysis, as described in the Examples. Calculated.

  In the polarizing plate (2), the iodine polarizer (1) and the transparent protective film are laminated by an adhesive layer formed of a water-soluble adhesive containing a polyvinyl alcohol resin containing an acetoacetyl group and a crosslinking agent. ing. By adhering the iodine-based polarizer (1) and the transparent protective film with such an adhesive, the water resistance is improved, and it is possible to achieve a shape or more even in a severe wet heat environment.

  The retardation layer-attached polarizing plate (3) has a dimensional shrinkage ratio of 0.5% or less represented by the following formula in the absorption axis direction, measured after standing at 80 ° C. for 24 hours. Dimensional shrinkage (%) = <{(dimension before leaving) − (dimension after leaving)} / (dimension before leaving)> × 100.

  By setting the dimensional shrinkage rate within the above range, dimensional shrinkage can be sufficiently suppressed, and depolarization in the peripheral portion can be effectively suppressed. The dimensional shrinkage is preferably 0.45% or less, more preferably 0.40% or less. The dimensional shrinkage rate is measured in detail by the method described in the examples.

  The adhesive type retardation layer-attached polarizing plate (4) has a single transmittance of 41.0 to 43.2%. If the single transmittance is less than 41.0%, the brightness at the time of white display becomes low, which is not preferable from the viewpoint of energy saving. On the other hand, if the single transmittance exceeds 43.2%, the optical characteristics in the reliability test When the change becomes large and the polarizing plates are arranged orthogonally, it is not preferable because red changes (the polarizing plate surface appears reddish) and unevenness are easily seen. From this viewpoint, the single transmittance is preferably 41.5 to 42.7%, and more preferably 41.8 to 42.4%. The single transmittance of the polarizing plate with an adhesive retardation layer (4) is generally 0.1 to 0 than the single transmittance of the iodine polarizer (1) due to the influence of the surface reflection of the pressure-sensitive adhesive layer and the retardation layer. .3% lower. The single transmittance is a Y value with respect to the C light source calculated based on the spectral transmittance (CIE1931) measured with a spectrophotometer for the adhesive-type retardation layer-attached polarizing plate (4) as described in Examples. is there.

  Moreover, the polarizing plate with an adhesive type retardation layer of the present invention is an acrylic adhesive formed by crosslinking reaction of an acrylic adhesive containing a (meth) acrylic polymer (A) and a crosslinking agent as an adhesive layer. An agent layer is preferably used. When the peroxide (B) and the isocyanate compound (C) are used in combination as the acrylic pressure-sensitive adhesive and the crosslinking agent, high durability that can suppress defects in appearance is satisfied even in the thermal shock test. it can.

It is an example of sectional drawing of the polarizing plate with an adhesion type phase contrast layer of the present invention.

  Below, the manufacturing method of the polarizing plate of this invention is demonstrated, referring drawings. FIG. 1 shows an example of an adhesive-type retardation layer-attached polarizing plate (4). FIG. 1 shows a polarizing plate (2) in which transparent protective films (21) and (22) are laminated on both surfaces of an iodine-based polarizer (1). The transparent protective films (21) and (22) are both bonded to the iodine polarizer (1) by the adhesive layers (23) and (24). The transparent protective film (21) on one side of the polarizing plate (2) shows a polarizing plate with a retardation layer (3) in which a retardation layer (31) is laminated, and the retardation layer (31) further includes a retardation layer (31). An acrylic pressure-sensitive adhesive layer (41) is laminated. In FIG. 1, the separator (5) is provided in the acrylic adhesive layer (41).

  Although not shown in FIG. 1, the acrylic pressure-sensitive adhesive layer (41) can be laminated on the retardation layer (31) via an anchor coat layer. In FIG. 1, the retardation layer (31) is directly laminated on the transparent protective film (21), but the retardation layer (31) is a pressure-sensitive adhesive layer or an adhesive layer, an easy-adhesion layer, They can be stacked via an alignment film or a combination of these layers.

  Although not shown in FIG. 1, the transparent protective film (22) can be laminated with various functional layers such as a hard coat layer, an antiglare layer, an antireflection layer, and the transparent protective film (22). Alternatively, a surface protective film can be laminated on the functional layer laminated thereon.

  As the iodine polarizer (1), those having the ratio (K / I) of 0.200 to 0.235 can be used without any particular limitation. The iodine (I) content of the iodine-based polarizer is usually 1.5 to 4.0% by weight, preferably 2.0 to 3.5% by weight. Moreover, content of potassium (K) is 0.3 to 0.9 weight% normally, Preferably it is 0.4 to 0.8 weight%, More preferably, it is 0.45 to 0.75 weight%.

  Examples of iodine-based polarizers include uniaxial stretching by adsorbing iodine to hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polyvinyl alcohol film and a polarizer made of iodine are preferable.

  As a polyvinyl alcohol film, a film formed by any method such as a casting method, a casting method or an extrusion method in which a stock solution in which a polyvinyl alcohol resin is dissolved in water or an organic solvent is cast is appropriately used. can do. The degree of polymerization of the polyvinyl alcohol-based resin is preferably about 100 to 5000, and more preferably 1400 to 4000. A saponification degree of about 80 to 100 mol% is generally used.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine or the like and uniaxially stretching is produced, for example, by the following method. The ratio (K / I) of the obtained iodine-based polarizer is controlled by adjusting the concentration of the solution used in the dyeing process or the like so as to be 0.200 to 0.235.

  In the dyeing process, the polyvinyl alcohol film is immersed in a dyeing bath at about 20 to 70 ° C. to which iodine is added for about 1 to 20 minutes to adsorb iodine. The iodine concentration in the dyeing bath is usually about 0.1 to 1 part by weight per 100 parts by weight of water. In the dyeing bath, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, etc. In general, an auxiliary such as iodide may be added in an amount of about 0.01 to 20 parts by weight, preferably 0.02 to 10 parts by weight per 100 parts by weight of water. These additives are particularly preferable for increasing the dyeing efficiency. In addition to the water solvent, a small amount of an organic solvent compatible with water may be contained.

  The polyvinyl alcohol film may be subjected to a swelling treatment at about 20 to 60 ° C. for about 0.1 to 10 minutes in a water bath or the like before being dyed in an aqueous iodine solution. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there.

  The dyed polyvinyl alcohol film can be cross-linked as necessary. The composition of the aqueous crosslinking solution used for the crosslinking treatment is usually about 1 to 10 parts by weight with 100 parts by weight of water alone or mixed with a crosslinking agent such as boric acid, borax, glyoxal, and glutaraldehyde. The concentration of the crosslinking agent is determined in consideration of the balance between the optical properties and the contraction of the polarizing plate caused by the stretching force generated in the polyvinyl alcohol film.

  In the crosslinking bath, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, etc. Aids such as iodide may be added to a concentration of 0.05 to 15% by weight, preferably 0.5 to 8% by weight. These additives are particularly preferable from the viewpoint of obtaining in-plane uniform characteristics of the polarizer. The temperature of the aqueous solution is usually about 20 to 70 ° C, preferably 40 to 60 ° C. The immersion time is not particularly limited, but is usually about 1 second to 15 minutes, preferably 5 seconds to 10 minutes. In addition to the water solvent, a small amount of an organic solvent compatible with water may be contained.

  The total draw ratio of the polyvinyl alcohol film is about 3 to 7 times, preferably 5 to 7 times the original length. When the total draw ratio exceeds 7 times, the film is easily broken. Stretching may be performed after dyeing with iodine, may be performed while dyeing or crosslinking, or may be dyed with iodine after stretching. The stretching method, the number of stretching, etc. are not particularly limited, and may be performed only in any one step. Moreover, you may carry out in multiple times by the same process.

  In addition, the polyvinyl alcohol film subjected to iodine adsorption alignment treatment is further added to an aqueous iodide solution such as potassium iodide having a water temperature of about 10 to 60 ° C., preferably about 30 to 40 ° C. and a concentration of 0.1 to 10% by weight. A step of dipping for 1 minute to 1 minute can be provided. In the iodide aqueous solution, auxiliary agents such as zinc sulfate and zinc chloride may be added. The polyvinyl alcohol film subjected to the iodine adsorption alignment treatment can be provided with a water washing step and a drying step of about 20 to 80 ° C. for about 1 minute to 10 minutes.

  In the drying step of the iodine-based polarizer (1), for example, a drying process can be performed in a state where a tension of 500 N / m or more is applied. When the film is stretched 5 to 7 times by wet stretching, unevenness of the periphery of the polarizer can be suppressed by applying a drying treatment in a state where such high tension is applied. The tension is preferably 550 N / m or more. The upper limit of the tension is not particularly limited and is appropriately set to such an extent that the film is not excessively stretched depending on the elastic modulus of the film and the like, but is usually 1200 N / m or less. In addition, the said tension | tensile_strength is measured by the method similar to the case where it applies to the below-mentioned polarizing plate (3) with a phase difference layer.

  The thickness of the iodine-based polarizer is not particularly limited, but is generally about 5 to 80 μm. When the thickness of the polarizer is reduced, moisture in the polarizer is likely to be volatilized in a drying process or the like when being bonded to the transparent protective film.

  In this invention polarizing plate (2), a transparent protective film is laminated | stacked on both sides of the said iodine type polarizer (1). As the transparent polymer or film material forming the transparent protective film, an appropriate transparent material can be used, but a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property and the like is preferably used. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and tricetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrenes such as polystyrene and acrylonitrile / styrene copolymer (AS resin) Examples thereof include polymers and polycarbonate polymers. In addition, polyethylene, polypropylene, polyolefin having a cyclo (cyclic) or norbornene structure, polyolefin polymer such as ethylene / propylene copolymer, vinyl chloride polymer, amide polymer such as nylon and aromatic polyamide, imide polymer, Sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers Or the blend of the said polymer etc. are mention | raise | lifted as an example of the polymer which forms the said transparent protective film. The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, and silicone.

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

  As the transparent protective film, a cellulose-based polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. On the other hand, a protective film such as triacetylcellulose has a large retardation value Rth in the thickness direction and has a problem of coloring, but contains an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the resin composition to be used, those having a thickness direction retardation value Rth of 30 nm or less can be used, and coloring can be almost eliminated.

  As said transparent protective film, what has a cyclic olefin resin as a main component is suitable. The cyclic olefin-based resin is a general generic name, and is described in, for example, Japanese Patent Application Laid-Open Nos. 3-14882 and 3-122137. Specifically, ring-opening polymers of cyclic olefins, addition polymers of cyclic olefins, random copolymers of cyclic olefins and α-olefins such as ethylene and propylene, and these are modified with unsaturated carboxylic acids or their derivatives. Examples of such graft-modified products can be given. Furthermore, these hydrides are mentioned. The cyclic olefin is not particularly limited, and examples thereof include norbornene, tetracyclododecene, and derivatives thereof. Examples of the products include ZEONEX and ZEONOR manufactured by Nippon Zeon Co., Ltd., Arton manufactured by JSR Corporation, and TOPAS manufactured by TICONA.

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

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

  Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The thickness of the transparent protective film is preferably 50 μm or less.

  On the surface of the transparent protective film on the side where the retardation layer (3) is not laminated (transparent protective film 22 in FIG. 1) to which the iodine polarizer (1) is not adhered, a hard coat layer, antireflection treatment, sticking prevention, Alternatively, it may be processed for the purpose of diffusion or antiglare.

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

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

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

  The polarizing plate (2) has an adhesive layer in which a transparent protective film is formed on both sides of the iodine polarizer (1) with a water-soluble adhesive containing a polyvinyl alcohol resin containing an acetoacetyl group and a crosslinking agent. Are stacked.

  The polyvinyl alcohol resin containing an acetoacetyl group is a polyvinyl alcohol-based adhesive having a highly reactive functional group, which is preferable because the durability of the polarizing plate is improved.

  A polyvinyl alcohol-based resin containing an acetoacetyl group is obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. For example, a method in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid and diketene is added thereto, a polyvinyl alcohol resin is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. And the like. Another example is a method in which diketene gas or liquid diketene is brought into direct contact with polyvinyl alcohol.

  The polyvinyl alcohol resin is polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; a saponified product of a copolymer with vinyl acetate and a copolymerizable monomer; polyvinyl alcohol acetal Examples thereof include modified polyvinyl alcohols that have been converted to urethanization, urethanization, etherification, grafting or phosphoric esterification. Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives and the like. . These polyvinyl alcohol resins can be used singly or in combination of two or more.

  The polyvinyl alcohol-based resin is not particularly limited, but from the viewpoint of adhesion, the average degree of polymerization is about 100 to 3000, preferably 500 to 3000, the average saponification degree is about 85 to 100 mol%, preferably 90 to 100 mol%. It is.

  The degree of acetoacetyl group modification of the polyvinyl alcohol-based resin containing an acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. If it is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient and unsuitable. The degree of acetoacetyl modification is preferably about 0.1 to 40 mol%, more preferably 1 to 20 mol%. When the degree of acetoacetyl modification exceeds 40 mol%, the number of reaction points with the cross-linking agent decreases, and the effect of improving water resistance is small. The degree of acetoacetyl modification is a value measured by NMR.

  As a crosslinking agent, what is used for the polyvinyl alcohol-type adhesive agent can be especially used without a restriction | limiting. As the crosslinking agent, a compound having at least two functional groups having reactivity with the polyvinyl alcohol resin can be used. For example, alkylenediamines having two alkylene groups and two amino groups such as ethylenediamine, triethylenediamine, hexamethylenediamine; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (Isocyanates such as 4-phenylmethane triisocyanate, isophorone diisocyanate and ketoxime block product or phenol block product thereof; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexane Diol diglycidyl ether, trimethylolpropane triglycidyl ether, di Epoxies such as ricidylaniline and diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succinaldehyde, glutardialdehyde, maleidialdehyde, phthaldialdehyde, etc. Dialdehydes; methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, condensates of benzoguanamine and formaldehyde, etc .; sodium, potassium, magnesium, calcium, aluminum, iron And a divalent metal such as nickel, or a salt of a trivalent metal and oxides thereof. Melamine is preferred.

  The amount of the crosslinking agent is usually about 0.1 to 30 parts by weight, preferably 10 to 25 parts by weight, with respect to 100 parts by weight of the polyvinyl alcohol resin. In such a range, a polarizing plate having uniform polarization characteristics and excellent durability can be obtained. On the other hand, in order to further improve the durability, the crosslinking agent can be blended in a range of more than 30 parts by weight and 46 parts by weight or less with respect to 100 parts by weight of the polyvinyl alcohol resin. In particular, when a polyvinyl alcohol-based resin containing an acetoacetyl group is used, it is preferable to use the crosslinking agent in an amount exceeding 30 parts by weight. By blending the crosslinking agent in the range of more than 30 parts by weight and 46 parts by weight or less, the water resistance can be drastically improved. The blending amount of the crosslinking agent is preferably as large as possible within the above range, and is preferably 31 parts by weight or more, more preferably 32 parts by weight or more, particularly preferably 35 parts by weight or more. On the other hand, if the amount of the crosslinking agent is too large, the reaction of the crosslinking agent proceeds in a short time and the adhesive tends to gel. As a result, the pot life as an adhesive is extremely shortened, making industrial use difficult. From such a viewpoint, the blending amount of the crosslinking agent is preferably 46 parts by weight or less, more preferably 45 parts by weight or less, and particularly preferably 40 parts by weight or less.

  The water-soluble adhesive further includes a coupling agent such as a silane coupling agent and a titanium coupling agent, various tackifiers, an ultraviolet absorber, an antioxidant, a heat stabilizer, and a hydrolysis stabilizer. A stabilizer or the like can also be blended.

  The polarizing plate (2) is obtained by laminating the transparent protective film and the iodine polarizer (1) using the water-soluble adhesive. Application | coating of the said adhesive agent may be performed to any of a transparent protective film and an iodine type polarizer, and may be performed to both. After the bonding, a drying process is performed to form an adhesive layer composed of a coating dry layer. Bonding of the iodine polarizer (1) and the transparent protective film can be performed with a roll laminator or the like. Although the thickness in particular of an adhesive bond layer is not restrict | limited, Usually, about 30-1000 nm, Preferably it is 100-500 nm.

  In preparing the polarizing plate (2), a resin layer can be provided on the surface of the transparent protective film to be bonded to the iodine-based polarizer (1) or an easy adhesion treatment can be performed. Examples of the easy adhesion treatment include dry treatment such as plasma treatment and corona treatment, chemical treatment such as alkali treatment, and coating treatment for forming an easy adhesive layer.

  The polarizing plate with a retardation layer (3) is obtained by providing a retardation layer on at least one transparent protective film of the polarizing plate (2).

  Examples of the retardation layer include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation layer is not particularly limited, but is generally about 20 to 150 μm.

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

  Examples of the liquid crystalline polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of main-chain liquid crystalline polymers include nematic-oriented polyester-based liquid crystalline polymers, discotic polymers, and cholesteric polymers that have a structure in which a mesogenic group is bonded to a spacer portion that imparts flexibility. It is done. Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. These liquid crystalline polymers can be obtained by, for example, applying a solution of a liquid crystalline polymer on an alignment surface such as one obtained by rubbing the surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate or one obtained by obliquely depositing silicon oxide. This is done by developing and heat treatment.

  The retardation layer may have an appropriate retardation according to the purpose of use, such as for the purpose of compensating for coloration or viewing angle due to birefringence of various wavelength plates and liquid crystal layers, for example. A layer in which optical characteristics such as retardation are controlled by laminating these retardation layers may also be used.

  A viewing angle compensation film can be used as the retardation layer. The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. Examples of such a viewing angle compensation phase difference plate include a phase difference plate, an alignment film such as a liquid crystal polymer, and a support in which an alignment layer such as a liquid crystal polymer is supported on a transparent substrate. A normal retardation plate uses a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the tilted alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, or a film obtained by obliquely aligning a liquid crystal polymer. Is given. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

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

  When a discotic liquid crystal compound is used, the tilted alignment state of the liquid crystalline molecules is determined depending on the molecular structure, the type of alignment film, and additives that are appropriately added to the optically anisotropic layer (eg, plasticizer, binder, surfactant). ) Can be controlled by using.

  The tilted orientation layer of the discotic liquid crystal polymer is preferably tilted in the range of 5 ° to 50 ° with a tilt angle formed from the average optical axis and the normal direction of the optical film.

  Further, by controlling the tilt angle to 5 ° or more, the viewing angle expansion effect when mounted on a liquid crystal display device or the like is great. On the other hand, by controlling the tilt angle to be 50 ° or less, the viewing angle is good in any direction (four directions) up, down, left and right, and the viewing angle may be improved or worsened depending on the direction. Can be suppressed. From this viewpoint, the inclination angle is preferably 10 ° to 30 °.

  The tilted orientation state of the discotic liquid crystalline molecules may be a uniform tilt (tilt) orientation that does not change with the distance in the film plane, and changes with the distance between the optical material and the film plane. Also good.

  The tilted alignment layer of the discotic liquid crystal polymer has an optical film with a controlled three-dimensional refractive index on its surface, so that a wide viewing angle can be realized and the gradation inversion region when viewed from an oblique direction. Is preferable for more effectively suppressing.

  The retardation layer is provided on the transparent protective film of the polarizing plate (2). The retardation layer can be laminated on the transparent protective film via, for example, an adhesive layer or an adhesive layer. Such lamination is suitable when the retardation layer is a birefringent film formed by uniaxially or biaxially stretching a polymer material.

  When the retardation layer is an alignment film of a liquid crystal polymer or an alignment layer of a liquid crystal polymer, those formed with a supporting substrate are usually used. Such a retardation layer can be formed by coating the supporting substrate with a liquid crystal material to coat the retardation layer and integrating the supporting substrate and the retardation layer. Such a supporting substrate can also serve as the transparent protective film of the polarizing plate (2). Alternatively, a retardation layer formed by coating a liquid crystal material may be separately transferred to a transparent protective film so that the transparent protective film and the retardation layer can be integrated. When arrange | positioning in this way, it can laminate | stack via an adhesive layer or an adhesive bond layer. Thus, when forming by coating the material of retardation layer, an easily bonding layer, alignment film, or the combination of these layers can be provided in a support base material.

  In the present invention, the support substrate on which the retardation layer is provided is preferably a liquid crystal polymer alignment layer formed on the support substrate so as to serve also as a transparent protective film. As the support substrate, a triacetyl cellulose film is suitable, and as the liquid crystal polymer alignment layer, a discotic liquid crystal tilt alignment layer is preferable.

  The retardation layer-attached polarizing plate (3) has a dimensional shrinkage ratio of 0.5% or less in the absorption axis direction measured after standing at 80 ° C. for 24 hours.

  In order to control the polarizing plate with retardation layer (3) to the dimensional shrinkage rate, it is preferable to perform drying after obtaining the polarizing plate with retardation layer (3) in a state where tension is not applied as much as possible. The tension is preferably 450 N / m or less and the heating temperature is preferably 60 to 120 ° C. for heat treatment. The heat treatment is preferably carried out while winding the polarizing plate with a retardation layer (3) after heating. In addition, when the tension exceeds 450 N / m, the dimensional shrinkage rate increases, which is not preferable for suppressing peripheral unevenness. From the viewpoint of productivity, it is preferable to perform the heat treatment while winding with a roll. Considering the roll winding property, the tension is preferably 60 to 450 N / m. On the other hand, when the temperature is lower than 60 ° C., the retardation layer-attached polarizing plate (3) cannot be sufficiently contracted, and the dimensional change after the heat treatment becomes large. On the other hand, when it exceeds 120 ° C., optical properties such as hue are inferior. The heat treatment is suitable for a high draw ratio of 5 to 7 times when the iodine-type polarizer (1) is produced, and particularly suitable for a case where a drying treatment is performed at a high tension. is there.

  The tension of the heat treatment is preferably 70 to 350 N / m, more preferably 90 to 150 N / m. The magnitude of the tension can be adjusted by the torque of the roll, and the application method is not particularly limited. However, when the polarizing plate (3) with a retardation layer is fed by a roll and subjected to continuous heat treatment, the feeding is performed. Can be given in the direction. The tension can be measured by, for example, a load cell type tension pick-up roll that can be measured by a load applied to the transport roll.

  The temperature of the heat treatment is preferably 60 to 90 ° C, more preferably 60 to 80 ° C. The heat treatment time is, for example, 60 to 600 seconds, preferably 120 to 480 seconds.

  The polarizing plate with a retardation layer (4) of the present invention is obtained by laminating an acrylic pressure-sensitive adhesive layer on the retardation layer side of the polarizing plate with a retardation layer (3). 0 to 43.2%. In addition, as above-mentioned, the single-piece | unit transmittance satisfies the same single-piece | unit transmittance also about the polarizing plate (4) with an adhesive type retardation layer because the iodine type polarizer (1) satisfies the said single-piece | unit transmittance. it can.

  The acrylic pressure-sensitive adhesive layer is preferably formed by crosslinking reaction of an acrylic pressure-sensitive adhesive containing the (meth) acrylic polymer (A) and a crosslinking agent.

  The alkyl group of the alkyl (meth) acrylate (a1) constituting the main skeleton of the (meth) acrylic polymer (A) has about 1 to 18 carbon atoms, preferably 1 to 9 carbon atoms. Specific examples of the (meth) acrylate include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, 2-ethylhexyl (meth) ) Acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, lauryl (meth) acrylate, isononyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. These can be used alone or in combination. The average carbon number of these alkyl groups is preferably 3-9. (Meth) acrylate refers to acrylate and / or methacrylate, and (meth) of the present invention has the same meaning.

  Although the (meth) acrylic polymer (A) can have only the alkyl (meth) acrylate (a1) as a monomer unit, other monomers can be copolymerized in addition to the alkyl (meth) acrylate (a1). it can. Examples of the copolymerization monomer include a carboxyl group-containing monomer, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, an acid anhydride group-containing monomer, a hydroxyl group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, and an imide group-containing monomer. And monomers having a functional group that functions as an adhesive group such as an epoxy group-containing monomer or as a crosslinking base. These functional group-containing monomers may be used alone or in combination of two or more. Among these, for example, a hydroxyl group-containing (meth) acrylic monomer (a2) is suitable.

  Specific examples of the hydroxyl group-containing (meth) acrylic monomer (a2) include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, ( 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) -methyl acrylate, etc. Is given. These can be used alone or in combination.

  The hydroxyl group-containing (meth) acrylic monomer (a2) is preferably a case where the alkyl group in hydroxyalkyl has 4 or more carbon atoms because of high reactivity with the isocyanate compound (C). As the hydroxyl group-containing (meth) acrylic monomer (a2), when the alkyl group in the hydroxyalkyl group has 4 or more carbon atoms, the alkyl (meth) acrylate (a1) has a carbon number of the alkyl group, It is preferable to use an alkyl group in the hydroxyalkyl of the hydroxyl group-containing (meth) acrylic monomer (a2) having the same number or less as the carbon number. For example, when 4-hydroxybutyl (meth) acrylate is used as the hydroxyl group-containing (meth) acrylic monomer (a2), the alkyl (meth) acrylate (a1) is butyl (meth) acrylate or butyl (meta It is preferable to use those having an alkyl group having a smaller number of carbon atoms than the acrylate.

  Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Of these, acrylic acid and methacrylic acid are particularly preferably used. Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth). Examples include acryloyloxynaphthalene sulfonic acid. Examples of the phosphoric acid group-containing monomer include 2-hydroxyethylacryloyl phosphate.

  The copolymerization amount of the functional group-containing monomer is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the alkyl (meth) acrylate (a1). When the functional group-containing monomer is a hydroxyl group-containing (meth) acrylic monomer (a2), the amount of copolymerization is 0.01 to 5 with respect to 100 parts by weight of the alkyl (meth) acrylate (a1). Part by weight is preferred. When the copolymerization amount of the hydroxyl group-containing (meth) acrylic monomer (a2) is less than 0.01 parts by weight, the number of crosslinking points with the isocyanate crosslinking agent is decreased, which is not preferable in terms of adhesion to the retardation layer and durability. . On the other hand, when the amount exceeds 5 parts by weight, the number of crosslinking points is excessive, which is not preferable in terms of stress relaxation. The copolymerization amount of the hydroxyl group-containing (meth) acrylic monomer (a2) is preferably 0.01 to 4 parts by weight, and more preferably 0.03 to 3 parts by weight.

  In addition, in the (meth) acrylic polymer (A) of the present invention, the monomer that can be copolymerized with the alkyl (meth) acrylate (a1) includes a cyano group-containing monomer, a vinyl ester monomer, an aromatic in addition to the functional group-containing monomer. A cohesive force / heat resistance improving component such as a group vinyl monomer can be contained. Other copolymerization components can be used together with the functional group-containing monomer or without being used in combination with the functional group-containing monomer.

  Other copolymer components include, for example, benzyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate, (meth) acrylamide, vinyl acetate, (meth) acrylonitrile, etc. Those having no functional group are preferably exemplified, but not limited thereto. These copolymerization amounts are preferably 100 parts by weight or less, more preferably 50 parts by weight or less, with respect to 100 parts by weight of the alkyl (meth) acrylate (a1).

  The average molecular weight of the (meth) acrylic polymer is not particularly limited, but the weight average molecular weight is preferably 500,000 to 3,000,000 or more, more preferably 1,000,000 to 2,500,000, and 1,200,000. The production of the (meth) acrylic polymer is more preferably ˜2 million, and can be produced by various known methods, for example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method is appropriately selected. it can. As the radical polymerization initiator, various known azo and peroxide initiators can be used. The reaction temperature is usually about 50 to 80 ° C., and the reaction time is 1 to 8 hours. Among the above production methods, the solution polymerization method is preferable, and ethyl acetate, toluene and the like are generally used as the solvent for the (meth) acrylic polymer. The solution concentration is usually about 20 to 80% by weight.

  When a peroxide is used as the polymerization initiator, it is possible to use the remaining peroxide for the crosslinking reaction without being used for the polymerization reaction. In that case, the remaining amount of peroxide is quantified, and if the proportion of peroxide is less than the predetermined amount, it is used by adding peroxide so that it becomes a predetermined amount if necessary. .

  As the crosslinking agent, those having reactivity with the (meth) acrylic polymer (A) are preferably used. Examples of the crosslinking agent include peroxides, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, and metal salts. In addition, it can bridge | crosslink using an ultraviolet-ray or an electron beam. These crosslinking agents can be used alone or in combination of two or more, but peroxides and isocyanate crosslinking agents are preferred. In particular, it is preferable to use a peroxide and an isocyanate-based crosslinking agent in combination. Crosslinking with a peroxide is preferable from the viewpoint of stability over time after crosslinking, and an isocyanate-based crosslinking agent is preferable from the viewpoint of adhesiveness to an optical member. The crosslinking agent is usually used in the range of about 0.001 to 10 parts by weight, preferably 0.001 to 5 parts by weight, per 100 parts by weight of the (meth) acrylic polymer (A).

  As the peroxide (B), those capable of generating radicals by heating to achieve crosslinking of the (meth) acrylic polymer (A) can be used without particular limitation. In consideration of productivity, the one-minute half-life temperature is preferably about 70 to 170 ° C, more preferably 90 to 150 ° C. If the half-life temperature for 1 minute is too low, a crosslinking reaction may occur during storage before applying the pressure-sensitive adhesive, and the viscosity of the coated product may increase, making the coating impossible. On the other hand, if the half-life temperature for 1 minute is too high, the temperature during the crosslinking reaction will increase and other side effects will occur, the desired properties will not be obtained due to insufficient decomposition, and the peroxide will remain so that crosslinking will occur over time. There are cases where the reaction proceeds, which is not preferable.

  The half-life of the peroxide is an index representing the decomposition rate of the peroxide, and is the time for which the amount of peroxide decomposition is halved. The half-life time at an arbitrary temperature is described in a manufacturer catalog or the like, for example, described in Nippon Oil & Fats Co., Ltd. Organic Peroxide Catalog 9th Edition (May 2003).

  As the peroxide of the present invention, any radical active species can be used as long as it generates radical active species by heating or light irradiation to advance the crosslinking of the base polymer of the pressure-sensitive adhesive composition. However, the workability and stability are improved. Considering this, it is preferable to use a peroxide having a half-life temperature of 80 ° C. to 160 ° C., more preferably a peroxide having a half-life temperature of 90 ° C. to 140 ° C. If the half-life temperature for 1 minute is too low, the reaction proceeds at the time of storage before coating and drying, and the viscosity may become high and the coating may become impossible. On the other hand, if the half-life temperature is too high, Since the temperature becomes high, side reactions occur, and a large amount of unreacted peroxide remains, which may cause cross-linking over time.

  Examples of such peroxide (B) include di (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6 ° C.), di (4-t-butylcyclohexyl) peroxydicarbonate (1 Minute half-life temperature: 92.1 ° C.), di-sec-butyl peroxydicarbonate (1 minute half-life temperature: 92.4 ° C.), t-butyl peroxyneodecanoate (1 minute half-life temperature: 103 0.5 ° C), t-hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C), t-butyl peroxypivalate (1 minute half-life temperature: 110.3 ° C), dilauroyl peroxide ( 1 minute half-life temperature: 116.4 ° C.), di-n-octanoyl peroxide (1 minute half-life temperature: 117.4 ° C.), 1,1,3,3-tetramethylbutylperoxy-2 Ethyl hexanoate (1 minute half-life temperature: 124.3 ° C.), di (4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2 ° C.), dibenzoyl peroxide (1 minute half-life temperature: 130 0.0 ° C.), t-butyl peroxyisobutyrate (1 minute half-life temperature: 136.1 ° C.), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.) ) Etc. Especially, since the crosslinking reaction efficiency is excellent, di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116. 4 ° C), dibenzoyl peroxide (1 minute half-life temperature: 130.0 ° C) and the like are preferably used.

  The usage-amount of a peroxide (B) is 0.02-2 weight part with respect to 100 weight part of (meth) acrylic-type polymers (A), Preferably it is 0.05-1 weight part, More preferably, it is 0.00. 06 to 0.5 parts by weight. If the amount of the peroxide (B) used is less than 0.02 parts by weight, the crosslinking reaction becomes insufficient, which is not preferable from the viewpoint of durability. On the other hand, if it exceeds 2 parts by weight, it is not preferred because of poor crosslinking due to excessive crosslinking.

  The details of the reason why the above-described properties are exhibited by using the peroxide crosslinking are not clear, but are estimated as follows. In peroxide cross-linking with peroxides, the radicals (active species) generated from the peroxide cause hydrogen abstraction reaction of the polymer skeleton to generate radicals in the polymer skeleton, and the radicals on these polymer skeletons are coupled. Etc. to form a cross-link, the entire polymer skeleton is taken into the cross-linked structure, and the entire pressure-sensitive adhesive is cross-linked uniformly. As a result, even if processing such as punching is performed immediately after the cross-linking treatment, the adhesive can adhere to the cutting blade, and the post-processing paste will not show any performance, and the predetermined cross-linking treatment should be performed. Therefore, it is estimated that the characteristics are stabilized because no cross-linking reaction occurs over time.

  In addition, as a measuring method of the peroxide decomposition amount which remained after the reaction process, it can measure by HPLC (high performance liquid chromatography), for example.

  More specifically, for example, about 0.2 g of the pressure-sensitive adhesive composition after the reaction treatment is taken out, immersed in 10 ml of ethyl acetate, extracted by shaking at 25 ° C. and 120 rpm for 3 hours with a shaker, and then at room temperature. Leave for 3 days. Next, 10 ml of acetonitrile was added, shaken at 120 rpm at 25 ° C. for 30 minutes, and about 10 μl of the extract obtained by filtration through a membrane filter (0.45 μm) was injected into the HPLC for analysis. The amount of peroxide can be set.

  The isocyanate compound (C) used for the isocyanate crosslinking agent is tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated. Isocyanate monomers such as diphenylmethane diisocyanate and adduct isocyanate compounds obtained by adding these isocyanate monomers with polyhydric alcohols such as trimethylolpropane; isocyanurates, burette type compounds, and further known polyether polyols, polyester polyols, acrylic polyols, Ure obtained by addition reaction of polybutadiene polyol, polyisoprene polyol, etc. Such emission prepolymer type isocyanate. Among these isocyanate compounds (C), adduct isocyanate compounds such as xylylene diisocyanate are preferable from the viewpoint of improving the adhesion to the optical film.

  The amount of the isocyanate compound (C) used is 0.001 to 2 parts by weight, preferably 0.01 to 1.5 parts by weight, more preferably 100 parts by weight of the (meth) acrylic polymer (A). 0.02 to 1 part by weight. If the usage-amount of an isocyanate type compound (C) is less than 0.001 weight part, it is unpreferable at the adhesiveness with a retardation layer of a polarizing plate with a retardation layer (3), or durability. On the other hand, when the amount exceeds 2 parts by weight, the adhesion is improved accordingly, but when used in combination with the peroxide (B), the degree of crosslinking with the handling part mainly of crosslinking with the peroxide (B) is increased. If the total balance amount at the time of control is taken into consideration, the range is set.

  Although the details of the reason for expressing the above characteristics by using the above-mentioned isocyanate-based crosslinking agent are not clear, by crosslinking the (meth) acrylic polymer with a specific amount of isocyanate-based crosslinking agent and peroxide, The (meth) acrylic polymer has a structure in which both crosslinking by a peroxide (peroxide crosslinking) and crosslinking by an isocyanate crosslinking agent (isocyanate crosslinking) are present. For this reason, sufficient cohesive force and stress applied to the pressure-sensitive adhesive are achieved by having a balanced main chain cross-linking (peroxide cross-linking) that is excellent in peroxide relaxation and a strong urethane bond (isocyanate cross-linking) with an isocyanate cross-linking agent. It is presumed that it exhibits a behavior that can relax. As a result, it is presumed that problems after the thermal shock test can be suppressed.

  Furthermore, the acrylic pressure-sensitive adhesive of the present invention includes a tackifier, a plasticizer, a glass fiber, a glass bead, a metal powder, a filler made of other inorganic powders, a pigment, a colorant, and a filler as necessary. An additive, an antioxidant, an ultraviolet absorber, a silane coupling agent, and the like, and various additives can be appropriately used without departing from the object of the present invention. Moreover, it is good also as an adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility.

  Among the additives, it is preferable to add a silane coupling agent. As a silane coupling agent, silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane; (Meth) acrylic group-containing silane coupling agents such as propyltrimethoxysilane; acetoacetyl group-containing trimethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane; 3-isocyanatopropyltrieth And isocyanate group-containing silane coupling agents such as Shishiran the like. In particular, 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane are preferably used because peeling can be effectively suppressed. The silane coupling agent can provide durability, particularly an effect of suppressing peeling in a humidified environment. The amount of the silane coupling agent used is 1 part by weight or less, further 0.01 to 1 part by weight, preferably 0.02 to 0.6 part by weight based on 100 parts by weight of the (meth) acrylic polymer (A). Part. When the amount of the silane coupling agent used is increased, the adhesive force to the liquid crystal cell is excessively increased, which may affect the reworkability.

  In the present invention, it is preferable to adjust the addition amount of the crosslinking agent (peroxide and isocyanate crosslinking agent) so that the gel fraction of the crosslinked acrylic pressure-sensitive adhesive layer is 40 to 95% by weight, It is more preferable to adjust the addition amount of the crosslinking agent so as to be 45 to 90% by weight, and it is further preferable to adjust the addition amount of the crosslinking agent so as to be 50 to 85% by weight. When the gel fraction is smaller than 35% by weight, the cohesive force is lowered, so that the durability may be inferior. When it exceeds 95% by weight, the adhesiveness may be inferior.

The gel fraction of the pressure-sensitive adhesive composition in the present invention means that after the dry weight W ₁ (g) of the pressure-sensitive adhesive layer is immersed in ethyl acetate, the insoluble content of the pressure-sensitive adhesive layer is taken out from the ethyl acetate and dried. The weight W ₂ (g) was measured, and the value calculated as (W ₂ / W ₁ ) × 100 was taken as the gel fraction (% by weight).

More specifically, for example, W ₁ (g) (about 500 mg) was collected from the pressure-sensitive adhesive layer after crosslinking. Next, the pressure-sensitive adhesive layer was immersed in ethyl acetate at about 23 ° C. for 7 days, and then the pressure-sensitive adhesive layer was taken out and dried at 130 ° C. for 2 hours. W ₂ (g) of the obtained pressure-sensitive adhesive layer Was measured. By applying W ₁ and W ₂ to the above formula, the gel fraction (% by weight) was determined.

  In order to adjust to a predetermined gel fraction, it is necessary to fully consider the influence of the crosslinking treatment temperature and the crosslinking treatment time as well as adjusting the addition amount of the peroxide and the isocyanate crosslinking agent.

  For example, when the acrylic pressure-sensitive adhesive contains a peroxide, the crosslinking treatment temperature and the crosslinking treatment time are preferably adjusted so that the decomposition amount of the peroxide is 50% by weight or more. It is more preferable to set the weight to be 70% by weight or more, and it is more preferable to set the weight to 70% or more. When the peroxide decomposition amount is less than 50% by weight, the amount of peroxide remaining in the pressure-sensitive adhesive composition increases, and a crosslinking reaction over time may occur even after the crosslinking treatment.

  More specifically, for example, at a crosslinking treatment temperature of 1 minute half-life temperature, the decomposition amount of peroxide is 50% by weight in 1 minute, and the decomposition amount of peroxide is 75% by weight in 2 minutes. A crosslinking treatment time of 1 minute or longer is required. Further, for example, if the peroxide half-life (half-life time) at the crosslinking treatment temperature is 30 seconds, a crosslinking treatment time of 30 seconds or more is required, and for example, the peroxide half-life at the crosslinking treatment temperature. If the (half time) is 5 minutes, a crosslinking treatment time of 5 minutes or more is required.

  Thus, the crosslinking treatment temperature and crosslinking treatment time can be calculated by theoretical calculation from the half-life (half-life time) assuming that the peroxide is linearly proportional to the peroxide used. It can be adjusted as appropriate. On the other hand, the higher the temperature, the higher the possibility of side reactions, so the crosslinking treatment temperature is preferably 170 ° C. or lower.

  Moreover, this crosslinking process may be performed at the temperature at the time of the drying process of an adhesive layer, and you may carry out by providing a crosslinking process process separately after a drying process.

  The crosslinking treatment time can be set in consideration of productivity and workability, but is usually about 0.2 to 20 minutes, preferably about 0.5 to 10 minutes.

  The material for forming the anchor coat layer provided between the pressure-sensitive adhesive layer and the phase-difference layer of the polarizing plate with a pressure-sensitive retardation layer of the present invention is not particularly limited, but is good for both the pressure-sensitive adhesive layer and the phase difference layer. It is desirable to form a film that exhibits excellent adhesion and excellent cohesion. Various polymers, metal oxide sols, silica sols, and the like can be used to exhibit such properties. Of these, polymers are particularly preferably used.

  Examples of the polymers include polyurethane resins, polyester resins, and polymers containing amino groups in the molecule. The polymer may be used in any of a solvent-soluble type, a water-dispersed type, and a water-soluble type. For example, water-soluble polyurethane, water-soluble polyester, water-soluble polyamide, etc. and water-dispersible resins (ethylene-vinyl acetate emulsion, (meth) acrylic emulsion, etc.) can be mentioned. The water-dispersed type is obtained by emulsifying various resins such as polyurethane, polyester and polyamide using an emulsifier, or by introducing an anionic group, a cationic group or a nonionic group of a water-dispersible hydrophilic group into the resin. The self-emulsified product can be used. Moreover, an ionic polymer complex can be used.

  Such polymers preferably have a functional group reactive with the isocyanate compound (C) in the pressure-sensitive adhesive layer. As the polymers, polymers containing an amino group in the molecule are preferable. In particular, those having a primary amino group at the terminal are preferably used.

  Examples of polymers containing an amino group in the molecule include polymers of amino-containing group-containing monomers such as polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, and dimethylaminoethyl acrylate. Of these, polyethyleneimine is preferred.

  Polyethyleneimine is not particularly limited, and various types can be used. The weight average molecular weight of polyethyleneimine is not particularly limited, but is usually about 1 to 1,000,000. For example, examples of commercially available polyethyleneimine include Epomin SP series (SP-003, SP006, SP012, SP018, SP103, SP110, SP200, etc.) manufactured by Nippon Shokubai Co., Ltd., and Epomin P-1000. Of these, Epomin P-1000 is preferred.

  The polyethyleneimine may be any one having a polyethylene structure, and examples thereof include an ethyleneimine adduct and / or a polyethyleneimine adduct to a polyacrylic acid ester. The polyacrylic acid ester can be obtained by emulsion polymerization of an alkyl (meth) acrylate and a copolymer monomer thereof constituting the base polymer (acrylic polymer) of the above-described acrylic pressure-sensitive adhesive according to a conventional method. As the copolymerization monomer, a monomer having a functional group such as a carboxyl group for reacting ethyleneimine or the like is used. The proportion of the monomer having a functional group such as a carboxyl group is appropriately adjusted depending on the proportion of ethyleneimine to be reacted. Moreover, as a copolymerization monomer, it is suitable to use a styrene-type monomer as above-mentioned. Moreover, it can also be set as the addition product which grafted polyethyleneimine by making the polyethyleneimine separately synthesize | combined react with the carboxyl group etc. in acrylic ester. For example, as an example of a commercially available product, Polyment NK-380 and 350 manufactured by Nippon Shokubai Co., Ltd. are particularly preferable.

  Further, an ethyleneimine adduct and / or a polyethyleneimine adduct of an acrylic polymer emulsion can be used. For example, as an example of a commercially available product, POLYMENT SK-1000 manufactured by Nippon Shokubai Co., Ltd. can be mentioned.

  The polyallylamine is not particularly limited, and examples thereof include diallylamine hydrochloride-sulfur dioxide copolymer, diallylmethylamine hydrochloride copolymer, polyallylamine hydrochloride, allylamine compounds such as polyallylamine, and polyalkylenepolyamines such as diethylenetriamine. And a condensate of dicarboxylic acid, an adduct of epihalohydrin, polyvinylamine and the like. Polyallylamine is preferred because it is soluble in water / alcohol. The weight average molecular weight of polyallylamine is not particularly limited, but is preferably about 10,000 to 100,000.

  In forming the anchor coat layer, in addition to the polymer containing an amino group, a compound that reacts with the polymer containing an amino group can be mixed and crosslinked to improve the strength of the anchor coat layer. Examples of the compound that reacts with the polymer containing an amino group include an epoxy compound.

  The pressure-sensitive adhesive layer in the polarizing plate with a pressure-sensitive retardation layer (4) of the present invention is obtained by crosslinking the acrylic pressure-sensitive adhesive having the above-described configuration. At that time, the pressure-sensitive adhesive is generally crosslinked after the application of the pressure-sensitive adhesive, but the crosslinked pressure-sensitive adhesive layer can be transferred to the retardation layer of the retardation layer-attached polarizing plate (3). It is.

  The method for forming the pressure-sensitive adhesive layer on the retardation layer is not particularly limited. For example, the pressure-sensitive adhesive is applied to a release-treated separator or the like, and the polymerization solvent is dried and removed to form the pressure-sensitive adhesive layer. The pressure-sensitive adhesive composition is prepared by a transfer method or a method in which the pressure-sensitive adhesive composition is applied to the retardation layer, and the polymerization solvent is dried and removed to form the pressure-sensitive adhesive layer on the retardation layer. In addition, when the pressure-sensitive adhesive is applied on the retardation layer, one or more solvents (solvents) other than the polymerization solvent may be newly added to the pressure-sensitive adhesive so that the pressure-sensitive adhesive can be applied uniformly on the retardation layer. .

  Examples of the solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, isopropanol, water and the like. These solvents may be used alone or in combination of two or more.

  Moreover, as a formation method of the adhesive layer used for this invention, the well-known method used for manufacture of adhesive sheets is used. Specifically, for example, by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  Moreover, in the said adhesive layer, the thickness of the said adhesive layer is 2-500 micrometers, Preferably it is about 5-100 micrometers. In addition, the surface of the pressure-sensitive adhesive layer may be subjected to easy attachment processing such as corona treatment, plasma treatment, and easy adhesion layer formation, and formation of an antistatic layer.

  Furthermore, when the pressure-sensitive adhesive is exposed on such a surface, the pressure-sensitive adhesive layer may be protected with a release sheet (separator, release film) that has been subjected to a release treatment until practical use.

  Examples of the constituent material of the separator include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foamed sheets, metal foils, and laminates thereof. A thin film can be used, but a plastic film is preferably used because of its excellent surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film. The thickness of the separator is usually 5 to 200 μm, preferably about 5 to 100 μm.

  For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the separator.

  In addition, in said manufacturing method, the sheet | seat which carried out the peeling process can be used as a separator of the polarizing plate (4) with an adhesion type phase difference layer as it is, and can simplify in a process surface.

  The polarizing plate with an adhesive retardation layer of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, one or more optical layers that may be used for forming a liquid crystal display device such as a reflection plate or a transflective plate can be used.

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

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

  Instead of the method of directly applying the reflecting plate to the transparent protective film of the polarizing plate, the reflecting plate can be used as a reflecting sheet provided with a reflecting layer on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective film, a polarizing plate or the like is used to prevent the reflectance from being lowered due to oxidation, and thus to maintain the initial reflectance for a long time. In addition, it is more preferable to avoid a separate attachment of the protective layer.

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

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

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

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

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

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

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

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

  An optical film obtained by laminating the optical layer on a polarizing plate with an adhesive retardation layer can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. The laminated optical film is excellent in quality stability and assembly work, and has the advantage of improving the manufacturing process of liquid crystal display devices and the like. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the above polarizing plate with an adhesive retardation layer and other optical films, their optical axes can be arranged at an appropriate angle depending on the intended retardation characteristics.

  In the present invention, each layer such as the above polarizing plate with an adhesive retardation layer and an optical film has, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, a nickel complex compound, etc. It may be one having a UV absorbing ability by a method such as a method of treating with a UV absorber.

  The polarizing plate with an adhesive retardation layer and the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing plate with an adhesive retardation layer or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no particular limitation except that the polarizing plate with an adhesive phase difference layer or the optical film of the present invention is used, and it can be based on the conventional method. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

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

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

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

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

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

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

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

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

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

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In each example, parts and% are based on weight unless otherwise specified.

  About the polarizer obtained by the Example and the comparative example, the polarizing plate with a phase difference layer, and the polarizing plate with an adhesion type phase difference layer, the physical property was measured with the following method. The results are shown in Table 1.

[Element content ratio]
The content of iodine (I) in the polarizer (% by weight) and the content of potassium (K) (% by weight) were subjected to fluorescent X-ray analysis to measure the content. From the measurement results, the element content ratio (K / I) was determined.
Measuring device: X-ray fluorescence analyzer ZSX100e, manufactured by Rigaku Denki Kogyo Co., Ltd. X-ray light source: Rh
Output: 40kV, 90mA
Measurement diameter: 10mmφ
Atmosphere: Vacuum Measurement method: A thin film standard sample was used, and quantitative analysis was performed with the thickness of the polarizer and the B content fixed.

[Dimensional shrinkage]
The retardation layer-attached polarizing plate was cut into a square test piece (10 cm × 10 cm) so that one side was parallel to the absorption axis direction. Cuts were made with a cutter at the center of the edge of each test piece so as to be parallel to the absorption axis direction of the polarizer, and the cut interval (size before leaving) was measured with calipers. And the incision interval (dimension after leaving) measured after leaving a test piece to stand at 80 degreeC for 24 hours was measured. From these results, the dimensional shrinkage rate (%) was determined by the following formula.
Dimensional shrinkage (%) = <{(dimension before leaving) − (dimension after leaving)} / (dimension before leaving)> × 100.

[Single transmittance]
About a polarizer and a polarizing plate with an adhesion type phase contrast layer, it measured with a spectrophotometer with an integrating sphere (U-4100 made by Hitachi, Ltd.). The transmittance for each linearly polarized light was measured with 100% of the completely polarized light obtained through the Glan-Thompson prism polarizer. Note that the transmittance is indicated by a Y value corrected for visual sensitivity calculated based on the CIE 1931 color system. k ₁ represents the transmittance of linearly polarized light in the maximum transmittance direction, and k ₂ represents the transmittance of linearly polarized light in the orthogonal direction. The single transmittance T was calculated by T = (k ₁ + k ₂ ) / 2.

Example 1
(Polarizer)
A polyvinyl alcohol film having a mean polymerization degree of 2400 and a saponification degree of 99.9 mol% and a thickness of 75 μm was immersed in warm water at 30 ° C. for 60 seconds to swell. Subsequently, it was immersed in an iodine aqueous solution having a concentration of 0.4% iodine / potassium iodide (weight ratio = 1/7), and dyed while stretching the film so that the stretching ratio was 3.5 times. Then, it extended | stretched so that the total draw ratio might be 6 times in 65 degreeC boric-acid-ester aqueous solution, and also it was immersed in 30 degreeC aqueous solution for 5 second at the potassium iodide density | concentration 3%. After extending | stretching, it dried for 3 minutes in 40 degreeC oven, and obtained the polarizer. The single transmittance of the polarizer was 42.4%.

(Transparent protective film)
A triacetyl cellulose film having a thickness of 80 μm was used.

(Transparent protective film with retardation layer)
A wide view film SA manufactured by Fuji Photo Film Co., Ltd. was used. The wide view film SA is obtained by fixing an alignment liquid crystal layer formed from an ultraviolet-curing discotic liquid crystal compound via an alignment film rather than a crosslinkable polyvinyl alcohol on a triacetyl cellulose base film.

(Polyvinyl alcohol adhesive)
With respect to 100 parts of polyvinyl alcohol resin containing acetoacetyl groups (average polymerization degree 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%), 32 parts of methylolmelamine were subjected to a temperature condition of 30 ° C. An aqueous adhesive solution was prepared by dissolving in pure water and adjusting the solid content concentration to 4%.

(Preparation of polarizing plate with retardation layer)
The adhesive was applied to one side of the transparent protective film (triacetyl cellulose film) so that the thickness of the adhesive layer after drying was 80 nm. On the other hand, the transparent protective film with a retardation layer was applied on the triacetyl cellulose base film on the side where the alignment liquid crystal layer was not formed so that the thickness of the adhesive layer after drying was 80 nm. . Each adhesive was applied under a temperature condition of 30 ° C. 30 minutes after the adjustment. Then, after bonding the transparent protective film and the transparent protective film with retardation layer on both surfaces of the polarizer under a temperature condition of 30 ° C. with a roll machine, in a state where a tension of 100 N / m was applied, at 70 ° C. It dried for 5 minutes and obtained the polarizing plate with a phase difference layer. The dimensional shrinkage ratio of the polarizing plate with a retardation layer was 0.39%.

(Preparation of adhesive)
In a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 99 parts of butyl acrylate, 1.0 part of 4-hydroxybutyl acrylate and 2,2′-azobisisobutyronitrile 0.3 After adding a part with ethyl acetate and making it react at 60 degreeC under nitrogen gas stream for 4 hours, ethyl acetate was added to the reaction liquid, and the solution (solid content concentration 30) containing an acrylic polymer with a weight average molecular weight of 150,000. %). 0.15 part of dibenzoyl peroxide (Nippon Yushi Co., Ltd .: Nyper BO-Y) and 0.02 part of trimethylolpropane xylene diisocyanate (Mitsui Takeda Chemical ( Ltd.): Takenate D110N) and 0.2 part of a silane coupling agent (manufactured by Soken Chemical Co., Ltd .: A-100, acetoacetyl group-containing silane coupling agent) were blended to obtain an acrylic pressure-sensitive adhesive.

(Preparation of a polarizing plate with an adhesive retardation layer)
The pressure-sensitive adhesive was coated on a separator made of a polyester film surface-treated with a silicone release agent and heat-treated at 155 ° C. for 3 minutes to obtain a pressure-sensitive adhesive layer having a thickness of 20 μm. A separator having a pressure-sensitive adhesive layer was transferred to the alignment liquid crystal layer of the polarizing plate with a retardation layer to produce a polarizing plate with an adhesive-type retardation layer. The gel fraction of the pressure-sensitive adhesive layer was 60% by weight.

Example 2
(Polarizer)
In Example 1, the concentration of the aqueous iodine solution was changed to 0.37%, and the polarizer was obtained in the same manner as in Example 1 except that the single transmittance of the obtained polarizer was changed to 43.2%. Got.

  In Example 1, except that the polarizer obtained above was used, a polarizing plate with a retardation layer was prepared in the same manner as in Example 1, and a polarizing plate with an adhesive retardation layer was further prepared. The dimensional shrinkage ratio of the retardation layer-attached polarizing plate was 0.40%.

Example 3
(Preparation of adhesive)
95 parts of butyl acrylate, 5 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate, 0.05 part of 2,2-azobisisobutyronitrile and 200 parts of ethyl acetate, equipped with nitrogen introduction pipe and cooling pipe The mixture was placed in a four-necked flask and sufficiently purged with nitrogen, and then a polymerization reaction was carried out at 55 ° C. for 20 hours with stirring under a nitrogen stream to obtain an acrylic polymer having a weight average molecular weight of 1,570,000. A polyisocyanate crosslinking agent comprising 0.08 part of 3-glycidoxypropyltrimethoxysilane and a tolylene diisocyanate adduct of trimethylolpropane as a crosslinking agent with respect to 100 parts of the solid content of the acrylic polymer solution. 8 parts were mixed uniformly to obtain an acrylic pressure-sensitive adhesive.

(Preparation of adhesive-type retardation layer-attached polarizing plate)
The pressure-sensitive adhesive was coated on a separator made of a polyester film surface-treated with a silicone release agent and heat-treated at 130 ° C. for 3 minutes to obtain a pressure-sensitive adhesive layer having a thickness of 25 μm. The separator formed with the pressure-sensitive adhesive layer was transferred to the alignment liquid crystal layer of the polarizing plate with retardation layer of Example 1 to produce a polarizing plate with adhesive-type retardation layer. The gel fraction of the pressure-sensitive adhesive layer was 6% by weight.

Comparative Example 1
(Polarizer)
In Example 1, the concentration of the iodine aqueous solution was changed to 0.35%, and the polarizer was obtained in the same manner as in Example 1 except that the single transmittance of the obtained polarizer was changed to 44.3%. Got.

  In Example 1, except that the polarizer obtained above was used, a polarizing plate with a retardation layer was prepared in the same manner as in Example 1, and a polarizing plate with an adhesive retardation layer was further prepared. The dimensional shrinkage ratio of the retardation layer-attached polarizing plate was 0.40%.

Comparative Example 2
(Polyvinyl alcohol adhesive)
For 100 parts of polyvinyl alcohol resin (average polymerization degree 1800, saponification degree 98.5 mol%), 25 parts of methylol melamine are dissolved in pure water under a temperature condition of 30 ° C., resulting in a solid content concentration of 4%. An aqueous adhesive solution adjusted as described above was prepared.

  In Example 1, except that the adhesive obtained above was used, a polarizing plate with a retardation layer was prepared in the same manner as in Example 1, and a polarizing plate with an adhesive retardation layer was further prepared. The dimensional shrinkage ratio of the retardation layer-attached polarizing plate was 0.39%.

Comparative Example 3
(Preparation of polarizing plate with retardation layer)
In preparation of the polarizing plate with a retardation layer of Example 1, after applying the said transparent protective film and the transparent protective film with a retardation layer on both surfaces of the polarizer with the roll machine, tension (500 N / m) was applied. In the state, a polarizing plate with a retardation layer was obtained in the same manner as in Example 1 except that it was dried at 70 ° C. for 5 minutes. The dimensional shrinkage ratio of the retardation layer-attached polarizing plate was 0.60%.

  A polarizing plate with an adhesive retardation layer was produced in the same manner as in Example 1 except that the polarizing plate with retardation layer obtained above was used.

Comparative Example 4
(Polarizer)
A polyvinyl alcohol film having a mean polymerization degree of 2400 and a saponification degree of 99.9 mol% and a thickness of 75 μm was immersed in warm water at 30 ° C. for 60 seconds to swell. Subsequently, it was immersed in an iodine aqueous solution having a concentration of 0.4% iodine / potassium iodide (weight ratio = 1/7), and dyed while stretching the film so that the stretching ratio was 3.5 times. Then, it extended | stretched so that the total draw ratio might be 6 time in 65 degreeC boric-acid-ester aqueous solution, and also it was immersed in 30 degreeC aqueous solution for 5 second at the potassium iodide density | concentration. After extending | stretching, it dried for 3 minutes in 40 degreeC oven, and obtained the polarizer. The single transmittance of the polarizer was 42.2%.

  In Example 1, except that the polarizer obtained above was used, a polarizing plate with a retardation layer was prepared in the same manner as in Example 1, and a polarizing plate with an adhesive retardation layer was further prepared. The dimensional shrinkage ratio of the retardation layer-attached polarizing plate was 0.40%.

(Evaluation)
The following physical properties were measured for the polarizer, the polarizing plate with a retardation layer, and the polarizing plate with an adhesive retardation layer obtained in Examples and Comparative Examples, and the following evaluation was performed on the polarizing plate with an adhesive retardation layer. The results are shown in Table 1.

(Check for redness after heating)
An adhesive type retardation layer-attached polarizing plate (100 mm × 100 mm) was left in an environment at 100 ° C. for 500 hours, then visually observed in a crossed Nicol state, and evaluated according to the following criteria.
○: Reddish and not visible.
X: When it looks reddish.

(Hot water delamination)
A polarizing plate with an adhesive retardation layer (50 mm × 25 mm) was immersed in hot water at 60 ° C., and after 2 hours, the state of contraction of the polarizer was visually observed at the end of the film and evaluated according to the following criteria. .
○: No shrinkage of 2 mm or more is observed from the end.
X: Shrinkage exceeding 2 mm is observed from the end.

(Surrounding unevenness)
A polarizing plate with an adhesive phase difference layer is cut out so that the absorption axis of the polarizing plate is 45 ° in a state where the pressure-sensitive adhesive layer is faced down in accordance with the display unit size of the liquid crystal panel, and a commercially available TN liquid crystal panel ( 19 inch size) after mounting the liquid crystal panel so that the absorption axes of the polarizing plates are orthogonal to each other, and after lighting for 500 hours at 80 ° C., visually observe the display non-uniformity when displaying black Observed and evaluated according to the following criteria.
◯: When unevenness at the periphery of the panel is not visible.
X: When the nonuniformity is clearly visually recognized in the periphery of the panel.

(Thermal shock)
After sticking a polarizing plate with an adhesive retardation layer (200 mm × 300 mm) to a glass plate, the environmental changes of leaving at −40 ° C. for 1 hour and standing at 80 ° C. for 1 hour were repeated 200 times, and then on the appearance Was visually observed and evaluated according to the following criteria.
○: When there is no significant change in appearance.
X: When a change in appearance (peeling at the end, foaming of the adhesive, etc.) is clearly seen.

  From Table 1, the adhesive polarizing plate with retardation layer of Examples has no redness after heating, hot water delamination, and peripheral unevenness, and can suppress changes in optical properties even under heating and humidification conditions. It can be seen that can be kept high. Also, among the examples, in particular, the adhesive layer was formed with an acrylic adhesive using a peroxide and an isocyanate compound as a crosslinking agent. It turns out that the high durability which can suppress the above malfunction can be satisfied.

DESCRIPTION OF SYMBOLS 1 Iodine type polarizer 2 Polarizing plate 21, 22 Transparent protective film 23, 24 Polyvinyl alcohol type adhesive layer 3 Polarizing layer-attached polarizing plate 31 Acrylic adhesive layer 4 Adhesive type retardation layer-attaching polarizing plate 5 Separator

Claims (12)

A polarizing plate with a retardation layer (3) having a retardation layer on at least one transparent protective film of a polarizing plate (2) having a transparent protective film laminated on both surfaces of the iodine polarizer (1), A polarizing plate with an adhesive retardation layer (4) in which an acrylic adhesive layer is laminated on the retardation layer side,
In the iodine polarizer (1), the ratio (K / I) of the content (wt%) of iodine (I) and the content (wt%) of potassium (K) in the polarizer is 0.200 to 0.00. 235,
In the polarizing plate (2), the iodine polarizer (1) and the transparent protective film are laminated by an adhesive layer formed of a water-soluble adhesive containing a polyvinyl alcohol resin containing an acetoacetyl group and a crosslinking agent. And
The retardation layer-attached polarizing plate (3) has a dimensional shrinkage ratio of 0.5% or less represented by the following formula in the absorption axis direction, measured after standing at 80 ° C. for 24 hours.
Dimensional shrinkage (%) = <{(Dimension before leaving) − (Dimension after leaving)} / (Dimension before leaving)> × 100,
The polarizing plate with an adhesive retardation layer (4) has a single transmittance of 41.0 to 43.2%.   The retardation layer-attached polarizing plate (3) transparently protects the retardation layer formed by coating the liquid crystal material on the transparent protective film, or by coating the liquid crystal material separately. The polarizing plate with an adhesive retardation layer according to claim 1, wherein the polarizing plate is disposed by transfer on a film, and the transparent protective film and the retardation layer are integrated.   The pressure-sensitive adhesive retardation film-attached polarizing plate according to claim 2, wherein the retardation layer is a layer in which a tilted alignment layer of discotic liquid crystal is fixed.   In the polarizing plate with an adhesive type retardation layer (4), the acrylic adhesive layer is formed by crosslinking reaction of an acrylic adhesive containing a (meth) acrylic polymer (A) and a crosslinking agent. The pressure-sensitive adhesive retardation film-attached polarizing plate according to claim 1, wherein   The (meth) acrylic polymer (A) contains 0.01 to 5 parts by weight of a hydroxyl group-containing (meth) acrylic monomer (a2) as a copolymer component with respect to 100 parts by weight of the alkyl (meth) acrylate (a1). The pressure-sensitive adhesive retardation film-attached polarizing plate according to claim 4, wherein   The acrylic pressure-sensitive adhesive contains 0.02 to 2 parts by weight of a peroxide (B) as a crosslinking agent with respect to 100 parts by weight of a (meth) acrylic polymer (A). Item 6. The polarizing plate with an adhesive retardation layer according to Item 4 or 5.   The acrylic pressure-sensitive adhesive comprises 0.001 to 2 parts by weight of an isocyanate compound (C) as a crosslinking agent with respect to 100 parts by weight of the (meth) acrylic polymer (A). Item 6. The polarizing plate with an adhesive retardation layer according to Item 4 or 5.   The acrylic pressure-sensitive adhesive is 0.02 to 2 parts by weight of a peroxide (B) and an isocyanate compound (C) 0.001 to 100 parts by weight of the (meth) acrylic polymer (A). 6. The polarizing plate with an adhesive retardation layer according to claim 4, comprising 2 parts by weight.   The pressure-sensitive adhesive retardation film-attached polarizing plate according to any one of claims 4 to 8, wherein the acrylic pressure-sensitive adhesive further contains a silane coupling agent.   The pressure-sensitive adhesive retardation layer-attached polarizing plate according to claim 1, wherein the acrylic pressure-sensitive adhesive layer is laminated on the retardation layer via an anchor coat layer.   An optical film using the polarizing plate with an adhesive retardation layer according to claim 1.   An image display device comprising the pressure-sensitive adhesive retardation film-containing polarizing plate according to claim 1 or the optical film according to claim 11.

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