TW201307087A - Composite polarizer and liquid crystal display device - Google Patents

Abstract

Provided is a composite polarizer comprising a first pressure-seneitive adhesive layer, a polarizing plate, a second pressure-sensitive adhesive layer, and a transparent plastic substrate that are laminated in that order, wherein the polarizing plate has a polarizing film, and a transparent protective film being in contact with the second pressure-sensitive adhesive layer, the first pressure-sensitive adhesive layer has a storage elastic modulus at 80 DEG C being in the range of 10 to 100 KPa, and the second pressure-sensitive adhesive layre has a storage elastic modulus at 80 DEG C being in the range of 0.1 to 60 KPa. Preferabbly, an antistatic layer is laminated on the surface of the transparent plastic substrate opposite the second pressure-sensitive sdhesive.

Description

Composite polarizing plate and liquid crystal display device

The present invention relates to a composite polarizing plate and a liquid crystal display device using the same.

As a composite polarizing plate for the purpose of thinning, it has been proposed to laminate a first pressure-sensitive adhesive layer, a polarizing plate (polarizing film), a second pressure-sensitive adhesive layer, and a composite polarizing plate of a transparent plastic substrate. The composite polarizing plate polarizer and the transparent plastic substrate are directly laminated via the second pressure bonding agent layer, and the second pressure bonding agent layer exhibits a storage modulus of 0.15 to 1 MPa in a temperature range of 23 to 80 ° C ( The pressure-sensitive adhesive layer of the storage modulus is referred to as (JP2010-39458-A).

Generally, the polarizing film is easily shrunk under high temperature and high humidity, and the pressure sensitive adhesive layer having a high storage modulus is used as the second pressure-sensitive adhesive layer of the bonding polarizer and the transparent plastic substrate in the composite polarizing plate. In an attempt to suppress shrinkage of the polarizing film and the transparent plastic substrate under high temperature and high humidity. However, when the laminated polarizing film and the transparent protective film are used, and the transparent protective film and the transparent plastic substrate are bonded to each other via the pressure-sensitive adhesive layer, when the pressure-sensitive adhesive layer having a high storage modulus is used, With the shrinkage of the polarizing film generated under high temperature and high humidity, the transparent plastic substrate also has a problem of shrinkage.

In a liquid crystal panel in which a liquid crystal cell is sandwiched by a pair of glass substrates, the alignment of the liquid crystal cell is controlled by an electric field applied thereto, so that the general glass substrate is provided with a function of preventing charging, but it is now desired to apply a composite polarized light to the liquid crystal panel. The board side is provided with a function to prevent charging. Here, in the case where the composite polarizing plate is provided with a function of preventing charging, for example, an antistatic layer is provided on the transparent plastic substrate, and the antistatic layer and the circuit substrate of the liquid crystal panel are connected by a conductive paste or a conductive tape. In the composite polarizing plate which shrinks under high temperature and high humidity as described above, the conductive paste or the conductive tape which connects the antistatic layer and the circuit board is cut.

Further, the glass substrate constituting the liquid crystal panel is also desirably reduced in thickness. Here, in the case of the composite polarizing plate described above, the first pressure-sensitive adhesive layer is bonded to the glass substrate, but the composite polarizing plate shrinks under high temperature and high humidity, and the thinned glass substrate may be thinned. Will produce a bend.

Therefore, an object of the present invention is to provide a composite polarizing plate that suppresses shrinkage under high temperature and high humidity, and particularly provides an antistatic layer on a transparent plastic substrate, the antistatic layer being separated by a conductive paste or a conductive tape. When the circuit board of the liquid crystal panel is connected to the circuit board, the composite polarizing plate of the conductive paste or the conductive tape is not cut even under high temperature and high humidity, and the glass substrate is bonded to the thinned glass substrate, even in the case of A composite polarizing plate that suppresses bending of a glass substrate under high temperature and high humidity.

The present invention has the following constitution.

[1] sequentially laminating a first pressure-sensitive adhesive layer, a polarizing plate, a second pressure-sensitive adhesive layer, and a composite polarizing plate of a transparent plastic substrate, wherein the polarizing plate has a polarizing film and is bonded to the second pressure-sensitive adhesive layer. a transparent protective film; the first pressure-sensitive adhesive layer has a storage modulus of 10 to 100 KPa at 80 ° C, and the second pressure-sensitive adhesive layer has a storage modulus of 0.1 to 60 at 80 ° C KPa.

[2] The composite polarizing plate according to [1], wherein the polarizing plate has a transparent protective film bonded to the first pressure-sensitive adhesive layer.

[3] The composite polarizing plate according to [1] or [2], wherein the transparent plastic substrate has a tensile modulus of from 2,000 to 4,500 MPa.

[4] The composite polarizing plate according to any one of [1] to [3] wherein the transparent plastic substrate has a thickness of 10 to 100 μm.

[5] The composite polarizing plate according to any one of [1] to [4] wherein the surface layer of the transparent plastic substrate opposite to the second pressure-sensitive adhesive layer has an antistatic layer.

[6] A liquid crystal display device comprising the composite polarizing plate according to the above [5], a liquid crystal panel having a circuit board, and a conductive paste of a circuit board connecting the antistatic layer of the composite polarizing plate and the liquid crystal panel (paste) ) or conductive tape (tape).

According to the present invention, a composite polarizing plate which suppresses shrinkage under high temperature and high humidity can be provided. In particular, it is possible to provide an antistatic layer on a transparent plastic substrate, and the antistatic layer is connected to the circuit board of the liquid crystal panel via a conductive paste or a conductive tape, and is not cut even under high temperature and high humidity. The composite polarizing plate of the conductive paste or the conductive tape can provide a composite polarizing plate which can suppress the bending of the glass substrate even when it is bonded to a thinned glass substrate even under high temperature and high humidity.

An example of the layer configuration of the composite polarizing plate of the present invention is schematically shown in Figs. 1 to 5. As shown in Fig. 1, the composite polarizing plate of the present invention 10, sequentially laminating a first pressure-sensitive adhesive layer 1, a polarizing film 3, a transparent protective film 2a, a second pressure-sensitive adhesive layer 4, and a composite polarizing plate of a transparent plastic substrate 5, wherein the second pressure-sensitive adhesive layer 4 is bonded to the transparent plastic substrate 5. Further, as shown in FIG. 2, a transparent protective film 2b may be provided between the first pressure-sensitive adhesive layer 1 and the polarizing film 3, and as shown in FIG. 3, the transparent plastic substrate 5 and the second pressure-sensitive layer The antistatic layer 6 can be laminated on the surface on the opposite side of the bonding layer 4. Further, as shown in FIG. 4, a phase difference plate 7 (also serving as a transparent protective film) may be provided between the first pressure-sensitive adhesive layer 1 and the polarizing film 3, as shown in FIG. The phase difference plate 7 and the third pressure-sensitive adhesive layer 8 may be provided between the pressure-sensitive adhesive layer 1 and the polarizing film 3. Further, on the opposite side of the first pressure-sensitive adhesive layer 1 from the polarizing film 3, a separator member (not shown) is bonded to the composite polarizing plate before bonding to other members.

Hereinafter, each layer will be described with reference to the drawings.

<Polarizer>

The polarizing plate of the present invention is one of constituent members of the composite polarizing plate, and has a polarizing film and a transparent protective film laminated on the side of the second pressure-sensitive adhesive layer. Such a polarizing plate can be composed of two layers of the polarizing film 3/transparent protective film 2a as shown in Fig. 1, and as shown in Fig. 2, it can be a transparent protective film 2b/polarizing film 3/transparent protective film 2a. 3 layers. From the viewpoint of versatility, the aforementioned three-layer structure is preferable.

<polarized film>

The polarizing film has a function of taking out linear polarized light from incident natural light, and for example, a polarizing film which is adsorbed to a polyvinyl alcohol-based resin film by using a dichroic dye can be used. a polyvinyl alcohol-based resin constituting a polarizing film, which can be obtained by polyethylene The acid vinyl ester resin is obtained by saponification. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate of a single polymer of vinyl acetate, for example, a copolymer of vinyl acetate and other monomers copolymerizable therewith, and the like. As other monomers copolymerizable with vinyl acetate, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides, and the like. The degree of saponification of the polyvinyl alcohol-based resin is usually from 85 to 100 mol%, more preferably 98 mol% or more. The polyvinyl alcohol-based resin can be further modified, and for example, polyethylene formaldehyde modified with an aldehyde, polyvinyl acetaldehyde or the like can be used. Further, the degree of polymerization of the polyvinyl alcohol-based resin is usually from 1,000 to 10,000, more preferably from 1,500 to 5,000.

When a film of such a polyvinyl alcohol-based resin is formed into a film, a raw material film as a polarizing film can be used. The film forming method of the polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a conventional method. The film thickness of the raw material film composed of the polyvinyl alcohol-based resin is not particularly limited, and is, for example, about 1 to 150 μm. When the easiness of stretching or the like is considered, the film thickness is preferably 10 μm or more.

The polarizing film is a step of performing one-axis stretching through the polyvinyl alcohol-based resin film, a step of adsorbing the dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and a polyvinyl alcohol adsorbing the dichroic dye. The resin film is produced by a step of treating with an aqueous solution of boric acid and a water washing step after treatment with the aqueous solution of boric acid. As the dichroic dye, for example, iodine or a dichroic organic dye can be used.

<Transparent protective film>

A transparent protective film is laminated on at least one side of the polarizing film. Both can be suitably joined by an aqueous solution, an organic solvent solution, a solventless type or the like. Agent bonding. As the transparent protective film, various resin films conventionally known as transparent protective films for polarizing plates can be used. In general, a cellulose acetate-based resin film, particularly a triacetyl cellulose film, is suitably used. In the case of a two-layer transparent protective film of a polarizing film, a conventional transparent resin film can be similarly used.

<Transparent Plastic Substrate>

The transparent plastic substrate may be a polyester resin such as an acrylic resin or polyethylene terephthalate, a cyclic olefin resin such as a polycarbonate or a norbornene resin, or the like, as long as it does not impede transparency. A cellulose ester resin such as cellulose acetate, or a resin film composed of polyethylene, polypropylene, polystyrene, or polyvinyl chloride. Among them, a polyethylene terephthalate film or a cellulose ester resin film is suitably used from the viewpoints of hardness, transparency, productivity, and price.

Polyethylene terephthalate, which can be directly reacted with terephthalic acid and ethylene glycol (and other dicarboxylic acids and/or other diols as needed), so-called direct polymerization, terephthalic acid The methyl ester is obtained by any production method such as a transesterification reaction method in which a methyl ester is subjected to a transesterification reaction with ethylene glycol (and a dimethyl ester of another dicarboxylic acid and/or another diol as needed). Further, polyethylene terephthalate may contain a conventional additive as needed. As a conventional additive, for example, a lubricant, an agglomerating agent, a thermal stabilizer, an antioxidant, an antistatic agent, a light stabilizer, an impact resistance improver, and the like. However, as a transparent plastic substrate laminated on a polarizing plate, transparency is necessary, and the amount of additives added is preferably at a minimum.

The extension is carried out by forming the aforementioned polyethylene terephthalate into a film. Stretching treatment can produce an extended polyethylene terephthalate film. The extension may be performed in the MD direction (flow direction) or the TD direction (direction perpendicular to the flow direction), the extension of the axis, the extension of the MD direction and the TD direction, the non-MD direction, and the non-TD direction. The direction is extended by oblique extension or the like. By performing such an extending operation, a polyethylene terephthalate film having high mechanical strength can be obtained. Among them, due to the biaxially extending bowing phenomenon, the diagonally extending PET has a 45° film in the MD direction, and is used as a transparent plastic substrate in a roll-to-roll manner. When the polarizing plate is bonded to the polarizing plate, the composite polarizing plate can be obtained. When the liquid crystal panel is viewed with polarized sunglasses, the identification error caused by the polarization axis of the polarized sunglasses being perpendicular to the polarizing axis of the polarizing plate can be eliminated. .

In the case of biaxial stretching, for example, an unaligned film which is extrusion-molded into a sheet shape, which is longitudinally stretched (extending in the MD direction) at a temperature higher than the glass transition temperature, and then laterally extended (extending in the TD direction) Or a method of extending the lateral direction at the same time.

The cellulose ester-based resin film is a film composed of a partially esterified or fully esterified cellulose, for example, a cellulose acetate, a propionate, a butyrate, or a mixed ester of these. More specifically, a cellulose triacetate film, a cellulose diacetate film, a cellulose acetate propionate film, a cellulose acetate butyrate film, and the like can be given. As such a cellulose ester-based resin film, a commercially available product such as Fujitac TD80 (made by Fujifilm Co., Ltd.), Fujitac TD80UF (made by Fujifilm Co., Ltd.), and Fujitac T40UZ (Fuji Film Co., Ltd.) can be used. ), Fujitac TD80UZ (Fuji Soft film (stock), KC8UX2M (Konica Minolta Opto), KC8UY (Konica Minolta Optical Co., Ltd.), KC4UY (Konica Minolta Optical Co., Ltd.) ))).

Further, in the present invention, as the transparent plastic substrate, a retardation film having a phase difference can be used. In this case, it is preferable that the retardation phase axis of the retardation film is disposed at an angle of about 45 with the absorption axis of the polarizing film. As the retardation film, for example, polyvinyl alcohol, polycarbonate, polyester, polyarylate, polyimide, polyolefin, cyclic olefin, polystyrene, polyfluorene, polyether oxime, polytetrafluoroethylene / A polymer film composed of polymethyl methacrylate, liquid crystal polyester, cellulose acetate, ethylene-vinyl acetate copolymer saponified product, polyvinyl chloride or the like is stretched to form an optical film exhibiting refractive index anisotropy. Further, a substrate having an optically isotropic structure having no phase difference is coated with a liquid crystal compound to exhibit a refractive index anisotropy; or a refractive index is expressed by coating of an inorganic layered compound. An anisotropic film can be used as a retardation film. In the case where a retardation film is used as the transparent plastic substrate, it is preferable to display a phase difference of 1/4 wavelength with respect to the wavelength of incident light, and the in-plane phase difference value in this case is generally 90 to 200 μm, which is preferable. It is 120 to 160 μm. The quarter-wave plate has a function of changing linearly polarized light emitted from the polarizing film to elliptically polarized or circularly polarized light. When the retardation film is used as the polarizing plate of the transparent plastic substrate, when the liquid crystal cell is placed on the front side of the liquid crystal cell, the polarizing lens is used to view the screen of the liquid crystal panel, and the polarization axis of the polarized sunglasses and the polarizing axis of the polarizing plate can be released. Poorly identified. Here, the polarized sunglasses are glasses including a polarizing plate and transmit only linearly polarized light that vibrates in one direction (for example, a lateral direction or a longitudinal direction).

From the viewpoint of resisting shrinkage under high temperature and high humidity of the polarizing plate, the transparent plastic substrate preferably has a tensile modulus of from 2,000 to 4,500 MPa.

The thickness of the transparent plastic substrate is appropriately selected depending on the material to be used, and is preferably 10 to 100 μm, more preferably 20 to 60 μm, still more preferably 25 to 40 μm.

<pressure-sensitive adhesive layer>

The composite polarizing plate 10 of the present invention includes a first pressure-sensitive adhesive layer 1 and a second pressure-sensitive adhesive layer 4 (Figs. 1 to 4), and a first pressure-sensitive adhesive layer 1 and a polarizing film. Between the three, the phase difference plate 7 and the third pressure-sensitive adhesive layer 8 may be provided.

The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may each have a predetermined storage modulus to be described later. For forming the pressure-sensitive adhesive layer, for example, an acrylic, rubber or urethane is used. A pressure-sensitive adhesive containing a resin such as an ester, an ester, a polyoxymethylene or a polyvinyl ether as a main component. Among these, a pressure-sensitive adhesive which is an acrylic resin which is excellent in transparency, weather resistance, heat resistance, and the like as a matrix polymer is suitable. In particular, it is preferable to maintain proper wettability and cohesive force, and to have good adhesion to a transparent protective film or a polarizing film, and it is preferable that no peeling or peeling problems occur under heating or humidification conditions. Further, it may be a pressure-sensitive adhesive called an energy ray-curing type or a thermosetting type. Further, as the bonding agent for forming the third pressure-sensitive adhesive layer, the same bonding agent as described above can be used.

The acrylic resin to be used for the formation of the pressure-sensitive adhesive layer is not particularly limited, and for example, butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, (methyl) is suitably used. ) 2-ethylhexyl acrylate An acrylate-based matrix polymer of the above type, and two or more of these acrylate-based copolymerization-based matrix polymers are used. Further, these matrix polymers may be copolymerized with a polar monomer. As a polar monomer, for example, (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, (meth)acrylic acid N,N' a monomer having a carboxyl group, a hydroxyl group, a decylamino group, an amine group, an epoxy group or the like, such as dimethylaminoethyl ester or glycidyl (meth)acrylate.

These acrylic resins can be used alone as a pressure-sensitive adhesive, but usually a crosslinking agent is prepared. As a crosslinking agent, for example, a divalent or polyvalent metal ion which forms a metal carboxylate with a carboxyl group, a polyamine compound which forms a guanamine bond with a carboxyl group, a polyepoxide which forms an ester bond with a carboxyl group, or A polyhydric alcohol, a polyisocyanate compound which forms a guanamine bond with a carboxyl group, or the like. Among them, polyisocyanate compounds are widely used as organic crosslinking agents.

The energy ray-curable pressure-sensitive adhesive refers to a property of being cured by irradiation with an energy ray such as an ultraviolet ray or an electron beam, and has an adhesive property before the irradiation of the energy ray, and is adhered to the adherend such as a film by an energy ray. A pressure-sensitive adhesive having a property of adjusting adhesion when irradiated and hardened. As the energy ray-curable pressure-sensitive adhesive, it is preferable to use an ultraviolet-curable pressure-sensitive adhesive. The energy ray-curable pressure-sensitive adhesive is generally composed of the above-mentioned acrylic resin and energy ray-polymerizable compound as main components. Usually, a crosslinking agent is prepared, and a photopolymerization initiator, a photosensitizer, or the like can be optionally added as needed.

In order to form the adhesive composition used for the pressure-sensitive adhesive layer, in addition to the above-mentioned matrix polymer and crosslinking agent, in order to adjust the pressure bonding as needed For the adhesion, cohesive force, viscosity, modulus of elasticity, glass transition temperature, etc. of the agent, for example, a resin of a natural or synthetic substance, an adhesive resin, an antioxidant, a dye, a pigment, an antifoaming agent, an etchant can be used. A suitable additive such as a photopolymerization initiator. Further, it contains microparticles and can be a pressure-sensitive adhesive layer which exhibits light scattering properties.

The pressure-sensitive adhesive layer is obtained by dissolving or dispersing the above-mentioned respective components in an organic solvent such as toluene or ethyl acetate to form a solid content concentration of 10 to 40% by weight, and applying it to a substrate. It can be formed by drying it to remove an organic solvent. In the case of the energy ray-curable pressure-sensitive adhesive, the coating film thus formed is irradiated with an energy ray such as an ultraviolet ray or an electron beam to obtain a desired cured product.

As a method of forming the pressure-sensitive adhesive layer, a conventionally known method can be employed, for example, (1) coating the above-mentioned adhesive composition on the adhered surface of the polarizing film or the transparent protective film, drying, and irradiating energy as needed. (2) A method of transferring a pressure-sensitive adhesive layer to an adherend surface of a polarizing film or a transparent protective film from a laminate in which a pressure-sensitive adhesive layer is formed on a surface of a partition member in advance. Further, from the viewpoint of improving the adhesion between the adhered surface and the pressure-sensitive adhesive layer, it is preferable to subject the adhered surface to corona treatment. Further, in the case where the pressure-sensitive adhesive layer is formed by the method of the above (1), it is preferable to bond the partition member in order to protect the layer.

The thickness of the pressure-sensitive adhesive layer is usually about 1 to 40 μm, and it is preferably 3 to 25 μm in order to reduce the thickness of the composite polarizing plate in terms of non-destructive workability, durability, and the like. Further, the thickness of the second pressure-sensitive adhesive layer is preferably 5 to 15 μm.

The pressure-sensitive adhesive layer may contain a filler, a pigment, a colorant composed of glass fibers, glass particles, resin particles, metal powder, other inorganic powder, etc., in order to exhibit fine particles for light scattering. , antioxidants, UV absorbers, etc. Examples of the ultraviolet absorber include a salicylate-based compound, a diphenylketone-based compound, a benzotriazole-based compound, a cyanoacrylate-based compound, and a nickel-salted salt-based compound.

<First pressure bonding agent layer>

The first pressure-sensitive adhesive layer has a storage modulus of 10 to 100 KPa at 80 °C. The first pressure-sensitive adhesive layer has the predetermined storage modulus, and for example, the composite polarizing plate of the present invention is bonded to the thinned glass substrate via the first pressure-sensitive adhesive layer, even at a high temperature and high temperature. Under the wet, the bending of the glass substrate can be suppressed. Further, from the viewpoint of suppressing the bending of such a glass substrate, the storage modulus of the first pressure-sensitive adhesive layer at 80 ° C is preferably 10 to 60 KPa, more preferably 20 to 50 KPa.

<Second Pressure Bonding Layer>

The second pressure-sensitive adhesive layer has a storage modulus of from 0.1 to 60 KPa at 80 °C. By the second pressure-sensitive adhesive layer having the predetermined storage modulus, the composite polarizing plate of the present invention can suppress the shrinkage of the polarizing plate and the transparent plastic substrate satisfactorily even under high temperature and high humidity. In particular, when an antistatic layer is provided on a transparent plastic substrate, and the antistatic layer is connected to the circuit board of the liquid crystal panel via a conductive paste or a conductive tape, the conductive paste or the conductive paste can be prevented even under high temperature and high humidity. Cutting of the conductive tape. Further, from the viewpoint of suppressing shrinkage as described above, the storage modulus of the second pressure-sensitive adhesive layer at 80 ° C is preferably 0.1 to 40 KPa, more preferably 0.1 to 30 KPa.

In order to control the second pressure-sensitive adhesive layer in the predetermined storage modulus, as a bonding agent for forming the second pressure-sensitive adhesive layer, the acrylic resin (1), the acrylic resin (2), and the polyoxyl oxide described later are contained. The adhesive of the polymer (3) and the crosslinking agent (4) is preferred.

<Acrylic Resin (1)>

Acrylic resin (1): an acrylic resin containing a structural unit (a) derived from the monomer (A) and a structural unit (b) derived from the monomer (B), and an acrylic resin having a weight average molecular weight of 1,000,000 to 2,000,000.

Monomer (A): (meth) acrylate represented by formula (A)

(In the formula (A), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group or an aralkyl group having 1 to 14 carbon atoms. The hydrogen atom of R ² may be substituted with an alkoxy group having 1 to 10 carbon atoms. )

Monomer (B): a monomer represented by the following (B-1) and/or the following (B-2)

(B-1): a monomer containing at least one carboxyl group and one olefinic double bond

(B-2): at least one polar functional group and olefinic group selected from the group consisting of a hydroxyl group, a decylamino group, an amine group, an epoxy group, an oxetanyl group, an aldehyde group, and an isocyanate group Double bond monomer

<Acrylic resin (2)>

Acrylic resin (2): an acrylic resin having a structural unit (a) and a structural unit (b) and having a weight average molecular weight of 50,000 to 500,000.

<Polyoxyl Oxygen (3)>

Polyoxyl Oxide (3): an oligomer containing 2 to 100 structural units (s) derived from a compound represented by the following formula (S). (However, in the polyoxyl oligo (3), two or more kinds of structural units (s) may be contained.)

(In the formula (S), R ³ and R ⁴ represent an alkyl group or a phenyl group, and X and Y represent a hydrogen atom, an alkyl group which may be substituted, a phenyl group which may be substituted, an alkoxy group which may be substituted, may be Substituted phenoxy, substituted aralkyl, substituted aralkoxy, vinyl, vinyloxy, 1,2-epoxycyclohexyl, 1,2-epoxycyclohexyloxy Base, styryl, styryloxy, methacryloxy, amine, ureide, sulfhydryl or isocyanate.)

The second pressure-sensitive adhesive layer preferably has a creep amount of 200 to 600 μm as measured by a predetermined test method described in Examples described below from the viewpoint of suppressing shrinkage of the composite polarizing plate under high temperature and high humidity. The range of 300 to 400 μm is more desirable.

<third pressure bonding agent layer>

When the phase difference plate is provided between the first pressure-sensitive adhesive layer and the polarizing film, the polarizing film and the phase difference plate may be joined via the third pressure-sensitive adhesive layer. Such a third pressure-sensitive adhesive layer preferably has a storage modulus of 0.15 to 1 MPa in the range of 23 to 80 ° C in the past. In order to obtain such a storage modulus, it is effective to prepare an amine ester acrylate oligomer, for example, in the above-mentioned adhesive composition. Re-irradiation energy in addition to such an amine ester acrylate oligomer The line makes it harder for the person to harden.

<phase difference plate>

As shown in FIGS. 4 and 5, the composite polarizing plate of the present invention may include a phase difference plate 7 between the first pressure-sensitive adhesive layer 1 and the polarizing film 3 instead of the transparent protective film 2b. Thereby, a composite polarizing plate which imparts a viewing angle compensation function to the liquid crystal cell can be formed, and a composite polarizing plate of an elliptical or circular polarization mode can be formed. Such a phase difference plate can be obtained, for example, by extending a thermoplastic resin film. The type of the thermoplastic resin film constituting the retardation film is not particularly limited, and a cyclic olefin resin such as polycarbonate or a norbornene-based resin is exemplified, in addition to the cellulose acetate-based resin.

Moreover, an optical compensation film can be used as the phase difference plate. The optical compensation film is an optical compensation film which forms a coating layer of an inorganic layered compound so as to exhibit a phase difference in the thickness direction, and a coating layer which forms a liquid crystalline compound, in order to compensate for an optical phase difference when the polarizing plate is mounted on the liquid crystal display. Optical compensation film. A commercially available optical compensation film that forms a coating layer of a liquid crystal compound, for example, "WHITE VIEW" (also referred to as "WV film") sold by Fujifilm Co., Ltd., JX Nippon Mining & Energy Co., Ltd. "NH film", "NV film", etc. sold.

The retardation plate and the retardation phase axis of the optical compensation film and the angle formed by the absorption axis of the polarizing film are not particularly limited, and can be appropriately set according to the specifications of the liquid crystal cell to be applied. In the case of a composite polarizing plate having a viewing angle compensation function in which a phase difference plate or an optical compensation film is bonded, it is preferable to suppress the occurrence of discoloration more effectively than a laminated plate having only a polarizing plate and a phase difference plate.

<Antistatic layer>

As shown in Fig. 3, the antistatic layer 6 can be laminated on the side opposite to the surface of the transparent plastic substrate 5 joined to the second pressure-sensitive adhesive layer 4. The antistatic layer 6 may contain a transparent resin which is cured by a resin and which becomes a transparent antistatic agent, a fluorine-based or polyfluorinated leveling agent, and a solvent-drying resin. It is applied to the transparent plastic substrate 5, and is formed by curing the transparent resin by ultraviolet rays. Generally, in order to obtain the function as an antistatic layer, the surface resistance value is preferably 10 ¹⁴ Ω/□ or less, and more preferably 10 ¹² Ω/□ or less.

The resin becomes a transparent antistatic agent after curing, and includes an organic antistatic agent and an inorganic antistatic agent. An organic antistatic agent such as a cationic antistatic agent having a cationic group such as a 4-grade ammonium salt, a pyridinium salt or a 1 to 3-membered amine group; having a sulfonate group, a sulfate group, a phosphate group, An anionic antistatic agent such as an anionic group such as a phosphonate group; an amphoteric antistatic agent such as an amino acid or an amine sulfate; or a nonionic antistatic such as an amino alcohol, a glycerin or a polyethylene glycol Various surfactant-type antistatic agents such as agents; and polymer-type antistatic agents such as the above-mentioned antistatic agent, which can be polymerized by ionizing radiation using a 3-stage amine group and a 4-stage ammonium group. A monomer or oligomer, for example, a polymerizable antistatic agent such as an N,N-dialkylammonioalkyl (meth) acrylate monomer or a compound of the above-mentioned class 4.

As the inorganic antistatic agent, fine particles such as ATO, SnO ₂ or ITO can be used, and in particular, the coating film after curing of the resin exhibits transparency, and the particle diameter is desirably equal to or less than the wavelength of visible light, that is, 700 nm or less. The amount of the inorganic antistatic agent to be added is desirably 10 to 80% by weight based on the resin. An organic antistatic agent or an inorganic antistatic agent having a particle diameter of not more than visible wavelengths is dispersed in a transparent resin, and by being applied to a transparent plastic substrate, a transparent plastic substrate which is transparent and has the ability to prevent charging can be obtained.

A coating method of a coating material containing an antistatic agent can be, for example, a conventional method such as a roll coating method, a gravure coating method, a screen coating method, or a fountain coating method.

<Other layers>

Further, by forming a surface treatment layer having a hard coat layer, an antiglare layer, and an antireflection layer together with the antistatic layer on the surface of the transparent plastic substrate, the visibility can be improved and the hardness and scratch resistance can be improved. However, in order to maintain the function of the antistatic layer, even in the case of having a surface treatment layer, the surface resistance value is preferably 10 ¹⁴ Ω/□ or less, and more preferably 10 ¹² Ω/□ or less.

The hard coat layer may be a smooth surface or a surface having irregularities, for example, a resin material such as a polyfluorene type, an acrylic type, an urethane acrylate type, or the like, which may be formed by coating alone or in combination with a filler. Layer. The hard coat layer can be applied by applying a hard coat resin by a conventional method such as a spin coating method or a micro gravure coating method. The thickness of the hard coat layer is from 1 to 30 μm, more desirably 3 μm or more, and desirably 20 μm or less. The refractive index is usually 1.65 or less, more preferably 1.45 to 1.65.

The anti-glare layer is formed to prevent the external light from being reflected on the surface of the polarizing plate, and is generally formed by a roughening method such as a sand blasting method or an embossing method, or a UV-curable resin mixture. A method in which a coating liquid of transparent fine particles is cured and then formed on the surface of a transparent plastic substrate. The above hard coat layer is provided with a surface unevenness When formed in the state, it can become an anti-glare layer.

The antireflection layer is formed for the purpose of preventing light reflection outside the surface of the polarizing plate, and can be provided by a conventional method. For example, it is formed by a coating method such as a micro gravure coating method or a physical vapor phase growth method such as vapor deposition or sputtering, by providing a layer such as an organic substance, a metal or a metal compound.

The organic substance used for forming the antireflection layer is, for example, a polymer in which a fluorine atom is introduced. As the metal, aluminum, silver, or the like is suitably used. The metal compound is generally an inorganic substance, and an inorganic oxide, an inorganic sulfide, an inorganic fluoride or the like can be used. Examples of the inorganic oxide include cerium oxide, zinc oxide, titanium oxide, cerium oxide, cerium oxide, indium tin oxide, tungsten oxide, molybdenum oxide, cerium oxide, aluminum oxide, zirconium oxide, and the like. Examples of the inorganic sulfides include zinc sulfide, barium sulfide, and the like. Examples of the inorganic fluoride include, for example, aluminum fluoride, lithium fluoride, sodium fluoride, magnesium fluoride, calcium fluoride, barium fluoride, barium fluoride, barium fluoride, barium fluoride, barium fluoride, and fluorination. Antimony, antimony fluoride, lead fluoride, etc. In the case where the antireflection layer is provided, at least one layer of the organic material, metal, metal compound or the like may be used, but it may be a plurality of layers as needed.

<Method of Manufacturing Composite Polarizing Plate>

An example of a method of producing the composite polarizing plate of the present invention will be described below. A polarizing plate is obtained by bonding a transparent protective film to one side or both sides of the polarizing film by a conventional bonding agent. Then, a first pressure-sensitive adhesive layer is laminated on the surface of the polarizing plate. On the outer side of the first pressure-sensitive adhesive layer, the partition member is usually attached.

On the other hand, a second pressure-sensitive adhesive layer is laminated on one surface of the transparent plastic substrate. Here, on the outside of the second pressure-sensitive adhesive layer, the surface thereof It is a common example to provide temporary protection of the partition member. On the other side of the transparent plastic substrate, an antistatic layer and other layers (hard coat layer, anti-glare layer, anti-reflection layer, etc.) may be provided, and the transparent plastic substrate may be laminated with the layer in advance. The pressure-sensitive adhesive layer may be provided with an antistatic layer or the like on the transparent plastic substrate after forming the three layers of the transparent plastic substrate/second pressure-sensitive adhesive layer/separating member.

Then, a composite polarizing plate can be obtained by bonding the transparent protective film of the previously obtained polarizing plate and the second pressure-sensitive adhesive layer of the peeling member.

The layer structure of the composite polarizing plate of the present invention is not limited to the above-described formation order. For example, the first and second pressure-sensitive adhesive layers may be formed on both surfaces of the polarizing plate, and then the transparent plastic substrate may be bonded.

As a method of bonding the polarizing plate and the transparent plastic substrate, a single-sheet bonding method or a sheet-to-roller composite bonding method can be employed. Moreover, a long transparent plastic substrate can be produced, and in the case where a large number is required, the roller-to-roller bonding method is particularly useful.

<Liquid crystal display device>

In the composite polarizing plate of the present invention, the first pressure-sensitive adhesive layer is bonded to the glass substrate of the liquid crystal panel, and can be a liquid crystal display device. Here, when the composite polarizing plate is protected by the partition member, it is peeled off and bonded to the liquid crystal panel. Further, from the viewpoint of antistatic property, the composite polarizing plate of the present invention, the opposite side of the joint surface of the transparent plastic substrate and the second pressure-sensitive adhesive layer, is preferably laminated with an antistatic layer, and in this case, the composite of the present invention It is preferable that the polarizing plate is disposed on the side of the liquid crystal display device with the antistatic layer as the outside.

Furthermore, the composite polarizing plate of the present invention is bonded to, for example, an organic EL. Like a display element, it can be an image display device.

<Electrically conductive paste or conductive tape>

As the conductive paste or the conductive tape, those having a sufficient conductivity and having an antistatic layer on the transparent plastic substrate and having good adhesion to the circuit board of the liquid crystal panel are appropriately selected. For example, a conductive rubber member, a rubber of a surface layer metal foil, a plastic member coated with a metal foil, a so-called metal solder containing at least one monomer or alloy of Au, Ag, Cu, Co, Ni, Sn, Pb, containing Au, A resin, a metal wiring or a metal foil tape of at least one monomer or alloy of Ag, Cu, Co, Ni, Sn, and Pb.

[Examples]

Hereinafter, the present invention will be further described by way of examples, but the present invention is not limited to the following examples.

<Measurement of storage modulus>

Two spherical samples of 25 ± 1 mg were prepared from the pressure-sensitive adhesive, and one of the samples was placed between three flat metallurgical implements to prepare a sample piece. For the sample piece, the dynamic viscoelasticity measuring device "DVA-200" manufactured by IT Measurement Control Co., Ltd. was used, and the storage modulus (G') at 80 ° C was measured by a non-resonant forced vibration method at a frequency of 10 Hz. The storage modulus of the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive at 80 ° C was measured by measuring the storage modulus (G') of such a pressure-sensitive adhesive at 80 °C.

Latent variable

The pressure-sensitive adhesive was applied to a polarizing plate SRW062A manufactured by Sumitomo Chemical Co., Ltd. At this time, the corona discharge treatment was performed on the pressure-sensitive adhesive layer side and the polarizing plate side under the conditions of 280 W and 10 m/min. Then cut into 25 mm After being ×100 mm in size, it was bonded to an alkali-free glass (made by Corning Co., Ltd., Eagle-XG), and then autoclaved at 5 MPa, 50 ° C, and 20 minutes to prepare a latent variable. Test piece. The test piece thus prepared was placed in a 23 ° C × 55% environment for 24 hours to cure, and a load of 1 kg was applied in parallel with the long side of the test piece. The amount of displacement of the pressure-sensitive adhesive layer from the start to 3000 seconds was measured by a laser displacement meter (manufactured by KEYENCE Co., Ltd.) as a latent variable.

<corona discharge device>

In the present embodiment, the following corona discharge device was used.

Corona surface treatment frame STR-1764, high frequency power supply CT-0212, high voltage transformer CT-T02W (all manufactured by Kasuga Electric Co., Ltd.).

<Transparent plastic substrate with antistatic layer>

As a transparent plastic substrate with an antistatic layer, "transparent protective film for optics made by letterpress printing company; 40KSPLR" was used. The tensile modulus of the substrate was 3431 to 4412 MPa in the MD direction, 2941 to 3431 MPa in the TD direction, and 45 μm in the thickness. Further, the surface resistance value of the antistatic layer was 5 × 10 ¹¹ Ω / □.

<pressure-sensitive adhesive layer>

As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, the following pressure-sensitive adhesive was used.

(1) Pressure-sensitive cement A

‧ Storage modulus at 80 ° C (G'); 34 KPa

‧ latent variable; 343μm

‧ film thickness; 10μm

(2) Pressure-sensitive adhesive B (manufactured by Sumitomo Chemical Co., Ltd., optical pressure-sensitive adhesive L2)

‧ Storage modulus at 80 ° C (G'); 227 KPa

‧ latent variable; 193μm

‧ film thickness; 5μm

(3) Pressure bonding agent C

‧ Storage modulus at 80 ° C (G'); 36 KPa

‧ latent variable; 254μm

‧ film thickness; 25μm

(4) Pressure-sensitive cement D

‧ Storage modulus at 80 ° C (G'); 53 KPa

‧ latent variable; 236μm

‧ film thickness; 10μm

<Example 1> (Modulation of Pressure Sensitive Adhesive C)

Based on the solid content, butyl acrylate (BA), methyl acrylate (MA), 2-phenoxyethyl acrylate (PEA), 2-hydroxyethyl acrylate (HEA) and acrylic acid (AA) were used as 69. A weight ratio of 20:9:1:1 was polymerized to obtain an acrylic resin having a weight average molecular weight of 1.5 million. Then, 100 parts by weight of the acrylic resin and 0.5% by weight of an adduct of a toluene diisocyanate of a crosslinking agent (trade name: CORONATE L, manufactured by Nippon Polyamine Co., Ltd.), an antistatic agent 2 parts by weight and 0.3 parts by weight of a decane compound (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed. Then, the mixture was diluted with methyl ethyl ketone (MEK) to a concentration of 15 %, an adhesive composition (pressure-sensitive adhesive C) was obtained.

(Modulation of Pressure Sensitive Adhesive A) "Modulation of Acrylic Resin (1)"

The butyl acrylate (BA) and the acrylic acid (AA) were polymerized in a weight ratio of 99:1 based on the solid content, to obtain an acrylic resin (1) having a weight average molecular weight of 1.3 million.

"Modulation of Acrylic Resin (2)"

Based on the solid content, butyl acrylate (BA), butyl methacrylate (BMA), methyl acrylate (MA) and 2-hydroxyethyl acrylate (HEA) are weighted at 35:44:20:1. The polymerization was carried out to obtain an acrylic resin (2) having a weight average molecular weight of 100,000.

"Modulation of Pressure Sensitive Adhesive A"

100 parts by weight (70:30 by weight) of the acrylic resin (1) and the acrylic resin (2), and an adduct of a toluene diisocyanate of a crosslinking agent (trade name: CORONATE L, Japanese polyamine ester) Industrial Co., Ltd.) 3 parts by weight and 0.3 parts by weight of a decane compound (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.), mixed with methyl ethyl ketone (MEK) to a concentration of 15 %, the adhesive composition (pressure-sensitive adhesive A) was obtained.

(Production of laminated body of transparent plastic substrate and second pressure-sensitive adhesive layer)

In the transparent plastic substrate with the antistatic layer, the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive A of the second pressure-sensitive adhesive layer is bonded to the surface without the antistatic layer, and the two layers are laminated. The layered body. Further, when the two were bonded together, corona discharge treatment was applied to each of the bonding surfaces under conditions of 280 W and 10 m/min to improve the adhesion between the pressure-sensitive adhesive layer and the plastic substrate.

(production of polarizing plate)

A polyvinyl alcohol film having a thickness of 75 μm, which is composed of polyvinyl alcohol having an average degree of polymerization of about 2400 and a degree of saponification of 99.9 mol% or more, is about 5 times as long as the dry one-axis extension, and is kept in a state of tension, impregnated at 60 ° C in pure water. After 1 minute, the solution was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Then, it was immersed at 72 ° C for 300 seconds in an aqueous solution of potassium iodide / boric acid / water in a weight ratio of 8.5 / 8.5 / 100. Subsequently, the mixture was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizing film in which iodine was adsorbed to polyvinyl alcohol.

On both surfaces of the polarizing film, a cellulose triacetate film having a thickness of 40 μm which was subjected to saponification treatment was applied as a transparent protective film. A water-based adhesive was used for lamination, and after bonding, the transparent protective film was bonded to the polarizing film by drying at 80 ° C for 5 minutes to prepare a polarizing plate composed of three layers of a transparent protective film/polarizing film/transparent protective film.

(Formation of the first pressure-sensitive adhesive layer)

A laminated body of the first pressure-sensitive adhesive layer and the polarizing plate is formed on the single surface of the polarizing plate by bonding the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive C to the first pressure-sensitive adhesive layer. . Further, when both were bonded together, corona discharge treatment was applied to each of the bonding surfaces under conditions of 280 W and 10 m/min to improve the adhesion between the first pressure-sensitive adhesive layer and the polarizing plate.

(Production of composite polarizer)

The polarizing plate to which the first pressure-sensitive adhesive layer is bonded is opposite to the first pressure-sensitive adhesive layer, and is bonded to the second pressure-sensitive adhesive layer of the transparent plastic substrate on which the second pressure-sensitive adhesive layer is formed. Make a composite polarizer. Again, fit In either case, corona discharge treatment was applied to each of the bonding surfaces in the same manner as before to improve the adhesion between the two.

(heat resistance test)

The composite polarizing plate was placed in a state where the absorption axis of the polarizing plate was 83° with respect to the long side, and cut into a size of 92 mm × 53 mm to prepare a sample for evaluation. Then, this evaluation sample was bonded to an alkali-free glass (made by Corning Co., Ltd., Eagle-XG), and then autoclaved at 5 MPa, 50 ° C, and 20 minutes to make the glass and the evaluation sample. The adhesion becomes sufficient.

Then, the sample for evaluation of the glass was heat-treated in a high temperature bath (85 ° C) for 100 hours, and then the dimensional change of the transparent plastic substrate was measured using a two-dimensional measuring device "NEXIV VMR-12072" manufactured by NIKON. Quantity (shrinkage). As a result, the dimensional change amount (shrinkage amount) on the long side was 131 μm, and the dimensional change amount (shrinkage amount) on the short side was 190 μm.

<Example 2> (modulation of pressure-sensitive adhesive D)

3 parts by weight of an acrylic resin (1) used in Example 1 and an adduct of a toluene diisocyanate of a crosslinking agent (trade name: CORONATE L, manufactured by Nippon Polyamine Co., Ltd.) And 0.3 parts by weight of a decane compound (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.), and diluted with methyl ethyl ketone (MEK) to a concentration of 15% to obtain an adhesive composition (pressure-sensitive composition) Adhesive D).

A composite polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive D was used instead of the pressure-sensitive adhesive A used in Example 1. Then, the same test panel as in Example 1 was applied to the same composite polarizing plate. In the measurement of the dimensional change amount (shrinkage amount) of the transparent plastic substrate, the dimensional change amount (shrinkage amount) on the long side was 185 μm, and the dimensional change amount (shrinkage amount) on the short side was 227 μm.

<Comparative Example 1>

A composite polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive B was used instead of the pressure-sensitive adhesive A used in Example 1. Then, as a result of measuring the dimensional change amount (shrinkage amount) of the transparent plastic substrate by the same test method as in Example 1, the same composite polarizing plate was used, and the dimensional change amount (shrinkage amount) on the long side was 289 μm, which was short. The amount of dimensional change (shrinkage amount) on the side was 335 μm.

Comparing the results of Example 1, Example 2 and Comparative Example 1, as shown in Example 1 and Example 2, the second pressure-sensitive adhesive layer (formed by the pressure-sensitive bonding agents A and D) was stored at 80 ° C. When the modulus (G') is 34 KPa and 53 KPa, the shrinkage of the transparent plastic substrate can be satisfactorily suppressed. In contrast, as shown in Comparative Example 1, the second pressure-sensitive adhesive layer (formed by the pressure-sensitive bonding agent B) When the storage modulus (G') at 80 ° C is 227 KPa, the shrinkage of the transparent plastic substrate cannot be sufficiently suppressed. Further, comparing the results of Example 1 and Example 2, it is understood that the second pressure-sensitive adhesive layer has a low storage modulus (G') at 80 ° C. Example 1 (formed by the pressure-sensitive adhesive A), transparent plastic The amount of shrinkage of the substrate is low.

1‧‧‧First pressure bonding agent layer

2a, 2b‧‧‧ transparent protective film

3‧‧‧ polarizing film

4‧‧‧Second pressure bonding agent layer

5‧‧‧Transparent plastic substrate

6‧‧‧Antistatic layer

7‧‧‧ phase difference plate

8‧‧‧ Third pressure bonding agent layer

10‧‧‧Composite polarizer

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

Fig. 2 is a view showing an example of a layer configuration of a composite polarizing plate of the present invention. Schematic diagram of the section.

Fig. 3 is a schematic cross-sectional view showing an example of a layer configuration of a composite polarizing plate of the present invention.

Fig. 4 is a schematic cross-sectional view showing an example of a layer configuration of a composite polarizing plate of the present invention.

Fig. 5 is a schematic cross-sectional view showing an example of a layer configuration of a composite polarizing plate of the present invention.

1‧‧‧First pressure bonding agent layer

2a‧‧‧Transparent protective film

3‧‧‧ polarizing film

4‧‧‧Second pressure bonding agent layer

5‧‧‧Transparent plastic substrate

10‧‧‧Composite polarizer

Claims (6)

A composite polarizing plate sequentially stacks a first pressure-sensitive adhesive layer, a polarizing plate, a second pressure-sensitive adhesive layer and a transparent plastic substrate, wherein the polarizing plate has a polarizing film and a transparent layer bonded to the second pressure-sensitive adhesive layer The protective film; the first pressure-sensitive adhesive layer has a storage modulus of 10 to 100 KPa at 80 ° C, and the second pressure-sensitive adhesive layer has a storage modulus of 0.1 to 60 KPa at 80 ° C. The composite polarizing plate according to claim 1, wherein the polarizing plate has a transparent protective film bonded to the first pressure-sensitive adhesive layer. The composite polarizing plate of claim 1, wherein the transparent plastic substrate has a tensile modulus of 2000 to 4500 MPa. The composite polarizing plate of claim 1, wherein the transparent plastic substrate has a thickness of 10 to 100 μm. The composite polarizing plate according to any one of claims 1 to 4, wherein the surface layer of the transparent plastic substrate opposite to the second pressure-sensitive adhesive layer has an antistatic layer. A liquid crystal display device comprising: a composite polarizing plate according to claim 5; a liquid crystal panel having a circuit substrate; and a conductive paste connecting the antistatic layer of the composite polarizing plate and the circuit substrate of the liquid crystal panel Material or conductive tape.