JP2010262155A - Composite polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite polarizing plate that is arranged on the viewer side of a display element and has a birefringent layer on the viewer side thereof and that provides a display apparatus which causes a viewer to hardly recognize uneven color or irregular luminance, when viewing a screen with polarized glasses worn, even when the display apparatus is left standing at a high temperature. <P>SOLUTION: The composite polarizing plate is formed, by layering a polarizer 1, a pressure-sensitive adhesive layer 2 and the birefringent layer 6, in this order, on a separator. The pressure-sensitive adhesive layer 2 is composed of a pressure-sensitive adhesive exhibiting 0.2-3 MPa storage modulus at 80°C. The composite polarizing plate is arranged on the viewer side of the display element so that the polarizer 1 is on the display element side, and the birefringent layer 6 is on the viewer side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a composite polarizing plate disposed on the viewer side of a display element.

  Polarized glasses have a polarizing film sandwiched between lenses, and the reflection of dazzling light can be cut by wearing polarized glasses. However, when viewing the screen of a liquid crystal display device or EL display device with polarized glasses, the screen becomes dark depending on the viewing angle. This is due to a decrease in transmittance due to a deviation between the direction of the polarization axis of the polarizing plate arranged on the viewer side of the display element in these display devices and the direction of the polarization axis of the polarizing glasses. This is a problem in car navigation systems, PNDs, aircraft cockpits, PDAs, mobile phones, fish finders, etc. that have many opportunities for observation. In view of this, it has been proposed to provide a birefringent layer such as a λ / 4 plate on the outside (viewer side) of the viewer side polarizing plate (see, for example, Patent Documents 1 to 3).

Japanese Patent Laid-Open No. 10-10523 JP 2005-352068 A JP 2008-83307 A

  When a birefringent layer is provided on the outside of the viewer-side polarizing plate via a pressure-sensitive adhesive layer, the color of the display device when viewed from the display device with polarized glasses after being left under high temperature, such as in a car in summer, Unevenness or brightness unevenness may be recognized. Accordingly, an object of the present invention is a composite polarizing plate that is disposed on the viewer side of the display element and has a birefringent layer on the viewer side, and viewed the screen with polarized glasses even when left at high temperatures. In such a case, it is an object of the present invention to provide a composite polarizing plate that can provide a display device in which color unevenness and brightness unevenness are hardly recognized.

  In order to achieve the above object, the present invention is arranged on the viewer side of the display element, and a polarizer, a pressure sensitive adhesive layer and a birefringent layer are laminated in this order from the display element side to the viewer side. The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having a storage elastic modulus of 0.2 to 3 MPa at 80 ° C. .

  By disposing the composite polarizing plate of the present invention on the viewer side of the display element, a display device that is difficult to recognize color unevenness and brightness unevenness when viewed on a screen with polarized glasses even when left at high temperatures. Obtainable.

It is a cross-sectional schematic diagram which shows an example of the layer structure of the composite polarizing plate of this invention. It is a cross-sectional schematic diagram which shows an example of the layer structure of the composite polarizing plate of this invention. It is a cross-sectional schematic diagram which shows an example of the layer structure of the composite polarizing plate of this invention.

  Hereinafter, the present invention will be described in detail with appropriate reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the composite polarizing plate of the present invention, with the viewer side facing up and the display element side facing down. In this example, a transparent protective layer 4 is provided on the viewer side of the polarizer 1, and a birefringent layer 6 is laminated on the viewer side via a pressure-sensitive adhesive layer 2. A pressure-sensitive adhesive layer 3 is provided on the display element side of the polarizer 1, and a separator 8 is disposed on the exposed surface of the pressure-sensitive adhesive layer 3, and the surface of the pressure-sensitive adhesive layer 3 is temporarily bonded until the display element is bonded. It is customary to protect the wear.

  The polarizer 1 is a film having a function of extracting linearly polarized light from incident natural light. For example, a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film can be used. The polyvinyl alcohol resin constituting the polarizer 1 can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes may be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is about 1,000-10,000 normally, Preferably it is about 1,500-5,000.

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of the polarizer 1. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 1 micrometer-150 micrometers. Considering easiness of stretching, the film thickness is preferably 10 μm or more.

  The polarizer 1 has a step of uniaxially stretching such a polyvinyl alcohol resin film, a step of dyeing the polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, and a dichroic dye being adsorbed. It is manufactured through a step of treating the polyvinyl alcohol-based resin film with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution. As the dichroic dye, iodine or a dichroic organic dye is used.

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 2 disposed between the polarizer 1 and the birefringent layer 6 adheres to the surface of another substance simply by pressing and pulls it from the adherend surface. In the case of peeling, it is a viscoelastic body that can be removed with almost no trace as long as the adherend has strength, and is also called an adhesive. The pressure-sensitive adhesive layer 2 can be formed on the basis of various pressure-sensitive adhesives conventionally used for image display devices. For example, there are acrylic, rubber, urethane, silicone, polyvinyl ether and the like. Moreover, an energy beam curing type, a thermosetting type, etc. may be sufficient. Among these, a pressure-sensitive adhesive using an acrylic resin having excellent transparency, weather resistance, heat resistance, and the like as a base polymer is preferable.

  The acrylic resin is not particularly limited, but (meth) such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Preferred are homopolymers of alkyl acrylates, copolymers of two or more alkyl (meth) acrylates, and copolymers of one or more alkyl (meth) acrylates with polar monomers. Used. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and 2-N, N-dimethylaminoethyl (meth). Mention may be made of monomers having a carboxy group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as acrylate and glycidyl (meth) acrylate.

  These acrylic resins can of course be used alone, but a crosslinking agent is usually used in combination. As the crosslinking agent, a divalent or polyvalent metal ion that forms a carboxylic acid metal salt with a carboxyl group, a polyamine compound that forms an amide bond with a carboxyl group, Examples thereof include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are widely used as organic crosslinking agents.

  The energy ray curable pressure sensitive adhesive has the property of being cured by irradiation of energy rays such as ultraviolet rays and electron beams, and has adhesiveness before the irradiation of energy rays and adheres to films and the like. It is a pressure-sensitive adhesive that has the property of adhering to the body and being cured by irradiation with energy rays to adjust the adhesion. As the energy ray curable pressure sensitive adhesive, it is particularly preferable to use an ultraviolet curable pressure sensitive adhesive. The energy beam curable pressure sensitive adhesive generally comprises an acrylic resin and an energy beam polymerizable compound as main components. Usually, a crosslinking agent is further blended, and a photoinitiator, a photosensitizer and the like can be blended as necessary.

  The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer 2 includes, in addition to the above base polymer and the crosslinking agent, if necessary, the pressure-sensitive adhesive's adhesive strength, cohesive force, viscosity, elastic modulus, Appropriate addition of, for example, natural or synthetic resins, tackifying resins, antioxidants, dyes, pigments, antifoaming agents, corrosives, photopolymerization initiators, etc. to adjust the glass transition temperature, etc. An agent can also be blended. Furthermore, it can also be set as the pressure sensitive adhesive layer which contains microparticles | fine-particles and shows light-scattering property.

  The pressure sensitive adhesive layer 2 is composed of a pressure sensitive adhesive exhibiting a storage elastic modulus of 0.2 to 3 MPa at 80 ° C. The storage elastic modulus can be measured by using a commercially available viscoelasticity measuring device, for example, a viscoelasticity measuring device “DYNAMIC ANALYZER RDA II” manufactured by REOMETRIC, as shown in Examples described later. The storage elastic modulus of a pressure-sensitive adhesive used in a normal image display device or an optical film therefor is about 0.1 MPa at the maximum, and compared with that, the pressure-sensitive adhesive layer 2 defined in the present invention has a storage elastic modulus. A storage elastic modulus of 0.2 to 3 MPa is a high value. By using such a high storage elastic modulus, that is, a hard pressure-sensitive adhesive, it is possible to suppress a dimensional change that occurs in a high temperature environment. That is, heat unevenness is less likely to occur.

  The reason why the heat unevenness hardly occurs is considered as follows. That is, when the composite polarizing plate is exposed to a high temperature, the birefringent layer 6 expands thermally. At that time, a normal pressure-sensitive adhesive becomes soft at a high temperature and the adhesive force also decreases, and therefore slip occurs between the pressure-sensitive adhesive layer and the birefringent layer. Next, when the temperature is returned to room temperature, the birefringent layer 6 tries to return to its original size, but at room temperature, the pressure-sensitive adhesive has a strong adhesive force, so that stress in the shearing direction is generated and the birefringent layer 6 has a phase difference unevenness. Occurs. On the other hand, since a hard pressure-sensitive adhesive is hard even at high temperatures, no slip occurs between the pressure-sensitive adhesive layer and the birefringent layer. For this reason, even when the temperature is returned to room temperature, no stress in the shearing direction occurs, and no retardation unevenness occurs in the birefringent layer 6.

  The means for setting the storage elastic modulus of the pressure-sensitive adhesive layer 2 to such a high value is not particularly limited. For example, an oligomer, specifically a urethane acrylate oligomer may be used in the above-described ordinary pressure-sensitive adhesive. It is effective to blend. Preferably, such a urethane acrylate oligomer blended and then cured by irradiation with energy rays exhibits a high storage elastic modulus. A pressure-sensitive adhesive in which a urethane acrylate oligomer is blended, or a film-like pressure-sensitive adhesive obtained by coating it on a support film and curing it with ultraviolet rays is known.

  The thickness of the pressure sensitive adhesive layer 2 is preferably 1 to 40 μm. In order to obtain a thin composite polarizing plate, it is desirable to form the pressure-sensitive adhesive layer 2 thinly within a range that does not impair properties such as workability and durability. For example, the thickness is preferably 3 to 25 μm. It is suitable for suppressing the dimensional change of the polarizer while maintaining excellent processability.

  As shown in FIG. 1, it is preferable to provide a transparent protective layer 4 made of a transparent resin film on one side or both sides of the polarizer 1. In FIG. 1, a transparent protective layer 4 is provided on the viewer side of the polarizer 1. As the transparent protective layer 4, an appropriate transparent film can be used. Among these, a film made of a resin excellent in transparency, uniform optical properties, mechanical strength, thermal stability, etc. is preferably used. For example, cellulose resin films such as triacetyl cellulose and diacetyl cellulose, polyester resin films such as polyethylene terephthalate and polyethylene isophthalate, polybutylene terephthalate, acrylic resin films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate, Examples include, but are not limited to, polycarbonate-based resin films, polyethersulfone-based resin films, polysulfone-based resin films, polyimide-based resin films, polyolefin-based resin films, and cyclic olefin-based resin films containing cyclic olefins such as norbornene. Is not to be done. An adhesive or a pressure sensitive adhesive can be used for bonding the transparent protective layer 4 and the polarizer 1.

  There is no particular limitation on the method for forming the pressure-sensitive adhesive layer 2 on the transparent protective layer 4. For example, the pressure-sensitive adhesive layer 2 is formed on the transparent protective layer 4 using the pressure-sensitive adhesive as described above. Thereafter, a method of laminating a separator made of a resin film subjected to a release treatment such as a silicone type, or a method of forming a pressure-sensitive adhesive layer 2 on the separator as described above and then transferring it onto the transparent protective layer 4 Etc. can be provided. Moreover, when forming the pressure sensitive adhesive layer 2 on the transparent protective layer 4, on the surface (one side or both) to which the transparent protective layer 4 or the pressure sensitive adhesive layer 2 is bonded, if necessary, You may perform the process for improving adhesiveness, for example, a corona treatment.

  In addition, when omitting the transparent protective layer 4, as a method of forming the pressure-sensitive adhesive layer 2 on the polarizer 1, the above-described method of forming the pressure-sensitive adhesive layer 2 on the transparent protective layer 4 and Similar methods can be used. In the case where a transparent protective layer is provided only on the display element side of the polarizer 1 or only on the display element side of the polarizer 1, an adhesive or a sensation is used for bonding the polarizer 1 and the display element side transparent protective layer. A pressure adhesive can be used.

  The birefringent layer 6 has a function of changing the emitted linearly polarized light into elliptically polarized light or circularly polarized light. In particular, as a birefringent layer that can convert linearly polarized light into circularly polarized light, a layer called a λ / 4 plate that exhibits a phase difference of ¼ wavelength with respect to the wavelength of light is used. The λ / 2 plate has a function of changing the direction of linearly polarized light. Furthermore, a λ / 2 plate and a λ / 4 plate may be laminated so that the optical axes intersect at a predetermined angle to form a broadband λ / 4 plate that exhibits a phase difference of ¼ wavelength over a wide wavelength range. it can.

  The birefringent layer 6 is preferably a λ / 4 plate that converts linearly polarized light into circularly polarized light, and more preferably a broadband λ / 4 plate having a small wavelength dependency. Specifically, the birefringent layer 6 preferably satisfies the formulas (1) and (2).

Formula (1): 0.71 <R450 / R590 <0.82
Formula (2): 133 nm <R550 <143 nm
R450: In-plane retardation value of the birefringent layer with respect to light having a wavelength of 450 nm R550: In-plane retardation value of the birefringent layer with respect to light having a wavelength of 550 nm R590: In-plane retardation of the birefringent layer with respect to light having a wavelength of 590 nm value

  The birefringent layer 6 is preferably composed of a plurality of layers, such as a laminate in which the λ / 2 plate and the λ / 4 plate are laminated so that the optical axes intersect at a predetermined angle.

  Further, the birefringent layer 6 is made of a blend polymer composed of a polymer having a positive refractive index anisotropy and a polymer having a negative refractive index anisotropy, or a positive refractive index anisotropy. Examples thereof include those comprising a copolymer having a polymer monomer unit having a polymer monomer unit having a negative refractive index anisotropy. As a commercial product, for example, “Pure Ace WR” manufactured by Teijin Chemicals Ltd. can be used. Among them, there is an oriented film of a copolymer having a polymer monomer unit having a positive refractive index anisotropy and a polymer monomer unit having a negative refractive index anisotropy having a larger wavelength dispersion than the polymer. Preferably used.

  A surface treatment layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided on the surface of the birefringent layer 6 as necessary. The hard coat layer is formed to prevent scratches on the surface of the composite polarizing plate, and mainly adheres to the birefringent layer 6 from an ultraviolet curable resin such as an acrylic or silicone resin. Those having excellent hardness are appropriately selected and can be formed on the surface of the birefringent layer 6.

  The antireflection layer is formed for the purpose of preventing reflection of external light on the surface of the composite polarizing plate, and can be formed by a known method. The antiglare layer is formed to prevent disturbance of visibility caused by external light reflected on the surface of the composite polarizing plate, for example, a roughening method such as a sandblasting method or an embossing method, In general, the surface of the birefringent layer 6 is formed to have a concavo-convex structure by a method of applying and curing a coating liquid in which transparent fine particles are mixed with an ultraviolet curable resin.

  The method for laminating the birefringent layer 6 and the pressure-sensitive adhesive layer 2 is not particularly limited, and may be performed by a conventionally known technique. As an example, a method of laminating using a bonding roll or the like so that the optical axis of the birefringent layer 6 is at a predetermined angle with respect to the polarization axis of the polarizer 1 can be mentioned.

  The pressure-sensitive adhesive layer 3 disposed on the display element side of the polarizer 1 may be a common one conventionally used for an image display device or an optical film therefor, and is stored as much as the pressure-sensitive adhesive layer 2. Elastic modulus is not necessary. For example, those based on acrylic polymers, silicone polymers, polyesters, polyurethanes, and the like can be used. Above all, like acrylic pressure-sensitive adhesives, it has excellent optical transparency, moderate wettability and cohesion, excellent adhesion to substrates, and weather resistance and heat resistance. It is preferable to select and use one that does not cause peeling problems such as floating and peeling under the conditions of heating and humidification.

  The pressure-sensitive adhesive layer 3 may contain fine particles for imparting light scattering properties as necessary, and is filled with glass fibers, glass beads, resin beads, metal powder, other inorganic powders, or the like. An agent, a pigment, a colorant, an antioxidant, an ultraviolet absorber and the like may be blended. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex compounds.

  The pressure-sensitive adhesive layer 3 is formed on the polarizer 1 by, for example, preparing a 10 to 40% by weight solution by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate. A pressure-sensitive adhesive layer is formed on a separator that has been subjected to a coating method directly on the surface of the polarizer 1 or a silicone-based release treatment in advance, and is transferred onto the polarizer 1. This can be done by a method or the like. Although the thickness of the pressure sensitive adhesive layer 3 is determined according to the adhesive force etc., it is the range of 1-50 micrometers normally.

  In the composite polarizing plate of the present invention, another optical layer can be disposed on the display element side of the polarizer. FIG. 2 is a schematic cross-sectional view showing an example of the layer structure of the composite polarizing plate. The composite polarizing plate shown in FIG. 2 eliminates the protective layer 4 from the composite polarizing plate shown in FIG. 1, and the pressure-sensitive adhesive layer on the display element side of the polarizer 1 is the same as the pressure-sensitive adhesive layer on the viewer side. About the thing comprised with the pressure sensitive adhesive which shows the storage elastic modulus of 0.2-3 Mpa at 80 degreeC, the separator 8 was peeled and the other optical layer 7 was arrange | positioned on the surface of the pressure sensitive adhesive layer 2 Is. In this example, the other optical layer 7 is composed of a retardation plate. The pressure-sensitive adhesive layer 3 is provided on the surface of the other optical layer 7, and the surface thereof is temporarily protected by a separator 8. The formation of the pressure-sensitive adhesive layer 3 on the other optical layer 7 may be performed in the same manner as the formation of the pressure-sensitive adhesive layer 3 on the polarizer 1.

  The other optical layer 7 can be composed of various resins as exemplified above as the resin constituting the protective layer 4. In particular, the other optical layer 7 has an in-plane retardation, and is advantageously composed of a function as a retardation plate. The other optical layer 7 having in-plane retardation is preferably selected to have characteristics required as a retardation plate, that is, its birefringence is optically uniform, and the protective function of the polarizer 1 and the liquid crystal cell It is used for the purpose of compensating for the phase difference of the display element (including the meaning of viewing angle compensation). For example, those conventionally used in image display devices can be used without limitation, birefringent films made of stretched films of various transparent polymers, discotic liquid crystals and nematic liquid crystals are aligned and fixed. Examples include a film and a film substrate on which the liquid crystal layer is formed. When the liquid crystal layer is fixed on the film substrate, a cellulose resin film such as triacetyl cellulose is preferably used as the film substrate for supporting the oriented liquid crystal layer.

  Examples of the polymer that forms the other optical layer 7 include, for example, polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polyolefins such as polypropylene, polyarylate, polyamide, and cyclic olefins such as norbornene as monomers. And the cyclic polyolefin type. The stretched film may be processed by an appropriate method such as uniaxial or biaxial. Moreover, the birefringent film which controlled the refractive index of the thickness direction of a film by applying shrinkage force and / or extending | stretching force under adhesion | attachment with a heat-shrinkable film can also be used.

  The other optical layer 7 can freely select the type of film made of the above-mentioned material as required practically, but in particular according to the thinning of the composite polarizing plate, the protective layer 4 It is also possible to comprise a resin film (other optical layer 7) having the function of a retardation plate.

  The composite polarizing plate of the present invention can be laminated with one or more optical layers exhibiting other optical functions when used. The optical layer is not particularly limited.

  In the composite polarizing plate of the present invention, the transparent plate 5 can be disposed on the viewer side of the birefringent layer 6. FIG. 3 is a schematic cross-sectional view showing an example of the layer structure of the composite polarizing plate. In the composite polarizing plate shown in FIG. 3, a transparent protective layer 4 is also arranged on the display element side (between the polarizer 1 and the pressure-sensitive adhesive layer 3) of the polarizer 1 of the composite polarizing plate shown in FIG. The birefringent layer 6 is laminated on the viewer side of the birefringent layer 6 via the pressure-sensitive adhesive layer 2, and the transparent plate 5 is disposed on the viewer side via the pressure-sensitive adhesive layer 2. ing. As a method for forming the pressure-sensitive adhesive layer 2 on the birefringent layer 6, a method similar to the method for forming the pressure-sensitive adhesive layer 2 described above on the transparent protective layer 4 can be used. .

  As the transparent plate 5, the same material as the transparent protective layer 4 described above can be used. Further, similarly to the birefringent layer 6, a surface treatment layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided on the surface of the transparent plate 5. In particular, the transparent plate 5 having a clear or antiglare hard coat layer is preferably arranged on the viewer side of the birefringent layer 6 with the hard coat layer facing the viewer side.

  The composite polarizing plate of this invention can be arrange | positioned at the viewer side of various image display elements, and can be set as an image display apparatus. For example, it can be arranged on the viewer side of the liquid crystal cell to form a liquid crystal display device. The liquid crystal cell used is arbitrary. For example, a liquid crystal display using various liquid crystal cells such as an active matrix driving type typified by a thin film transistor type and a simple matrix driving type typified by a super twisted nematic type. A device can be formed.

  Furthermore, the composite polarizing plate of the present invention is also effectively used for a circularly or elliptically polarizing plate having an antireflection function in an image display device other than a liquid crystal display device, for example, a flat display such as an organic EL display device. Of course, the image display apparatus to which the composite polarizing plate of the present invention is applied is not limited to those exemplified here.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, the storage elastic modulus is a value measured by the following method.

[Storage modulus]
The storage elastic modulus of the pressure-sensitive adhesive was obtained by a torsional shearing method with a frequency of 1 Hz using a measuring instrument “DYNAMIC ANALYZER RDA II” manufactured by REOMETRIC using a 8 mmφ × 1 mm thick cylinder as a test piece.

In the following examples, the following were used as pressure sensitive adhesives.

  Pressure-sensitive adhesive A: An organic solvent solution of a pressure-sensitive adhesive obtained by adding a urethane acrylate oligomer to a copolymer of butyl acrylate and acrylic acid and adding an isocyanate-based crosslinking agent is subjected to a release treatment. A sheet-like pressure-sensitive adhesive obtained by coating the release treatment surface of a 38 μm-thick polyethylene terephthalate film (separate film) with a die coater so that the thickness after drying is 15 μm. The storage elastic modulus of this pressure-sensitive adhesive was 0.4 MPa at 23 ° C. and 0.2 MPa at 80 ° C.

  Pressure-sensitive adhesive B: a commercially available sheet in which an acrylic pressure-sensitive adhesive layer having a thickness of 15 μm is provided on a release-treated surface of a polyethylene terephthalate film (separate film) having a thickness of 38 μm that has been subjected to a release treatment. Pressure sensitive adhesive. No urethane acrylate oligomer is blended. The storage elastic modulus of this pressure-sensitive adhesive was 0.05 MPa at 23 ° C. and 0.04 MPa at 80 ° C.

[Example 1]
On the transparent protective layer 4 side of a polarizing plate (“SR0661A” manufactured by Sumitomo Chemical Co., Ltd.) obtained by adhering a triacetyl cellulose film as a transparent protective layer 4 on one side of the polarizer 1, an aromatic polycarbonate as a birefringent layer 6 System λ / 4 plate ["Pure Ace WR" manufactured by Teijin Chemicals Ltd .: R450 = 115 nm, R550 = 138 nm, R590 = 142 nm, R450 / R590 = 0.81], layer 2 of pressure sensitive adhesive A Then, the polarizer 1 was bonded so that the absorption axis of the polarizer 1 and the slow axis of the aromatic polycarbonate-based λ / 4 plate form an angle of 45 °. Subsequently, the layer of the pressure sensitive adhesive B for bonding with a liquid crystal cell was provided in the polarizer 1 side of the polarizing plate, and the composite polarizing plate of the layer structure shown in FIG. 1 was obtained.

[Example 2]
A layer 2 of pressure-sensitive adhesive A is provided on both sides of the polarizer 1, and an aromatic polycarbonate λ / 4 plate (“Pure Ace WR” manufactured by Teijin Chemicals Ltd.) as a birefringent layer 6 is polarized on one side. The absorption axis of the optical element 1 and the slow axis of the aromatic polycarbonate-based λ / 4 plate are bonded so as to form an angle of 45 °. On the opposite side, a polynorbornene-based λ / 4 plate [Sumitomo] “CSES330140” manufactured by Chemical Co., Ltd.] was bonded so that the absorption axis of the polarizer 1 and the slow axis of the polynorbornene-based λ / 4 plate form an angle of 45 °. Next, a layer of a pressure-sensitive adhesive B for bonding to a liquid crystal cell was provided on the other optical layer 7 to obtain a composite polarizing plate having a layer structure shown in FIG.

[Example 3]
Polynorbornene λ / 4 plate (“CSES430140” manufactured by Sumitomo Chemical Co., Ltd.) as the birefringent layer 6 and polynorbornene λ / 2 plate (“CSES430275” manufactured by Sumitomo Chemical Co., Ltd.) as the birefringent layer 6 And the slow axis of the polynorbornene-based λ / 4 plate and the slow axis of the polynorbornene-based λ / 2 plate through the layer 2 of the pressure-sensitive adhesive A so as to form an angle of 60 °. It was. This laminated body was R450 = 107nm, R550 = 138nm, R590 = 148nm, R450 / R590 = 0.72. A polarizing plate (“SRW062A” manufactured by Sumitomo Chemical Co., Ltd.) in which a triacetyl cellulose film is bonded to both sides of the polarizer 1 as a transparent protective layer 4 on the λ / 2 plate side of the laminate is pressure-sensitive bonded. Through the layer 2 of the agent A, the slow axis of the λ / 2 plate and the absorption axis of the polarizer 1 are bonded so as to be 15 °, and the transparent plate 5 has a thickness of 40 μm on the λ / 4 plate side. The triacetyl cellulose film side of the hard coat film provided with a hard coat layer on one side of the triacetyl cellulose film was bonded via the pressure-sensitive adhesive A layer 2. Next, a layer of pressure-sensitive adhesive B for bonding to the liquid crystal cell was provided on the polarizing plate to obtain a composite polarizing plate having a layer structure shown in FIG.

[Example 4]
A polarizing plate with a pressure-sensitive adhesive ("SRW062A" manufactured by Sumitomo Chemical Co., Ltd.) formed by adhering a triacetylcellulose film as a transparent protective layer 4 on both sides of the polarizer 1 and a polycarbonate-based birefringent layer 6 as a birefringent layer 6 A λ / 4 plate (“SEF440138” manufactured by Sumitomo Chemical Co., Ltd .: R450 = 148 nm, R550 = 138 nm, R590 = 136 nm, R450 / R590 = 1.09) is passed through the layer 2 of the pressure-sensitive adhesive A. The polarizer 1 was bonded so that the absorption axis of the polarizer 1 and the slow axis of the λ / 4 plate form an angle of 45 °. Next, a layer of pressure-sensitive adhesive B for bonding to the liquid crystal cell was provided on the opposite side of the polarizing plate from the birefringent layer 6 to obtain a composite polarizing plate having a layer structure shown in FIG.

[Comparative Example 1]
A composite polarizing plate was obtained by performing the same operation as in Example 1 except that the pressure-sensitive adhesive B was used in place of the pressure-sensitive adhesive A.

[Comparative Example 2]
A composite polarizing plate was obtained in the same manner as in Example 4 except that the pressure-sensitive adhesive B was used instead of the pressure-sensitive adhesive A.

  The composite polarizing plate obtained in each example was attached to the viewer side of the liquid crystal cell (the viewer side polarizing plate was peeled off from the commercially available mobile phone “W53CA”) through the layer of the pressure-sensitive adhesive B. In addition, the display quality was confirmed by placing the screen vertically and horizontally through polarized glasses. Next, it was put into an oven at 80 ° C., taken out after 10 hours to room temperature, and after 2 hours, the display quality was confirmed by putting the screen vertically and horizontally through the polarizing glasses. The results are shown in Table 1.

1 ... Polarizer,
2 ... Pressure sensitive adhesive layer,
3 ... Pressure sensitive adhesive layer,
4 ... Transparent protective layer,
5 …… Transparent plate,
6: Birefringent layer,
7. Other optical layers,
8 …… Separator.

Claims (6)

  A composite polarizing plate disposed on the viewer side of the display element, wherein a polarizer, a pressure-sensitive adhesive layer, and a birefringent layer are laminated in this order from the display element side to the viewer side. A composite polarizing plate, wherein the pressure adhesive layer is a layer of a pressure sensitive adhesive exhibiting a storage elastic modulus of 0.2 to 3 MPa at 80 ° C.   The composite polarizing plate according to claim 1, wherein a transparent protective layer is disposed on one side or both sides of the polarizer. The composite polarizing plate according to claim 1 or 2, wherein the birefringent layer satisfies formulas (1) and (2).
Formula (1): 0.71 <R450 / R590 <0.82
Formula (2): 133 nm <R550 <143 nm
R450: In-plane retardation value of the birefringent layer with respect to light having a wavelength of 450 nm R550: In-plane retardation value of the birefringent layer with respect to light having a wavelength of 550 nm R590: In-plane retardation of the birefringent layer with respect to light having a wavelength of 590 nm value   The composite polarizing plate according to claim 1, wherein the birefringent layer includes a plurality of layers.   A copolymer in which the birefringent layer has a polymer monomer unit having a positive refractive index anisotropy and a polymer monomer unit having a negative refractive index anisotropy having a larger wavelength dispersion than the polymer. The composite polarizing plate according to claim 1, wherein the composite polarizing plate is an oriented film.   The transparent plate having a hard coat layer is disposed on the viewer side of the birefringent layer via the pressure-sensitive adhesive layer with the hard coat layer facing the viewer side. A composite polarizing plate according to 1.

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