JP2008003426A - Polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tough polarizing plate having high surface hardness and excellent antidazzle characteristics, and to provide a liquid crystal display provided with the polarizing plate. <P>SOLUTION: The polarizing plate is obtained by stacking: a protective layer A at least comprising an (a) layer and a (b) layer each containing a thermoplastic resin, and in which the bending elasticity of the (a) layer is higher than the bending elasticity of the (b) layer, and also, the (a) layer is present on the side of a reflection prevention layer; a polarizer; and a protective layer B in this order, and has a haze of 10 to 60%. A liquid crystal display is provided with the polarizing plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarizing plate that is tough, has high surface hardness, and excellent antiglare properties, and a liquid crystal display device including the polarizing plate.

The polarizing plate used for a liquid crystal display device etc. is a laminated body which consists of a polarizer and a protective film. As a polarizer constituting this polarizing plate, a film in which iodine or a dichroic dye is adsorbed on a film obtained by forming a film of polyvinyl alcohol by a solution casting method and stretched in a boric acid solution is usually used.
On the other hand, a triacetyl cellulose film is widely used as a protective film constituting the polarizing plate. However, since the triacetylcellulose film has poor moisture resistance and gas barrier properties, the durability, heat resistance, mechanical strength, etc. of the polarizing plate are insufficient.

2. Description of the Related Art Conventionally, it is widely known to produce a multilayer film that takes advantage of the characteristics of each resin by laminating a plurality of resins.
For example, Patent Document 1 describes a thermoplastic resin sheet for molding and a molded body thereof, wherein a thermoplastic resin sheet having at least two layers, at least one of which is an amorphous polyolefin. ing. It is described that this thermoplastic resin sheet is excellent in water vapor barrier properties and transparency, has no fusion with a mold, and can be molded in a wide temperature range.

  Patent Document 2 describes a polystyrene film comprising a sandwich laminate of polystyrene layer / acrylonitrile / butadiene / styrene copolymer layer / polystyrene layer. This laminated film is considered to be a film that is inexpensive, excellent in transparency and impact resistance, and has a good balance of tear strength in the longitudinal direction or the transverse direction.

  A technique using a multilayer film as a polarizing plate protective film is also known. For example, in Patent Document 3, a resin layer having a positive photoelastic constant and a resin layer having a negative photoelastic constant, which have lower moisture absorption than triacetylcellulose, are laminated, and the photoelastic constant is lower than a specific value. A polarizing plate protective film characterized by being small is described. Further, it is described that the polarizing plate protective film does not cause display unevenness or contrast reduction even when placed in a high temperature and high humidity environment.

  Patent Document 4 is composed of a three-layer laminate in which surface layers are laminated on both sides of an intermediate layer, and at least the intermediate layer contains an ultraviolet absorber, and the concentration of the ultraviolet absorber in the intermediate layer is higher than that of the surface layer. A norbornene-based resin film having an ultraviolet transmittance of 40% or less with a wavelength of 380 nm or less is described. Moreover, it is described that this resin film does not cause an appearance defect due to volatilization of the ultraviolet absorber during extrusion molding.

  On the other hand, an antiglare film in which an antiglare layer is laminated on a transparent resin base material is used as an antireflection film on the surface of flat panel displays such as liquid crystal displays, plasma displays, and organic electroluminescence displays. Such anti-glare films are required to be strong and have high surface hardness in addition to excellent anti-glare performance.

  However, none of the techniques relating to the multilayer film described in the above-mentioned patent documents can provide a polarizing plate having toughness and excellent surface hardness, and further improvements are required.

JP-A-6-255053 JP-A-8-281882 JP 2000-206303 A Japanese Patent Laid-Open No. 2002-249600

  The present invention has been made in view of the above-described prior art, and it is an object of the present invention to provide a polarizing plate that is tough and has high surface hardness and excellent antiglare properties, and a liquid crystal display device including the polarizing plate. And

  As a result of earnest research to solve the above problems, the present inventors have found that a layer containing a thermoplastic resin having a relatively large bending elastic modulus and b layer containing a thermoplastic resin having a relatively small bending elastic modulus. When an antireflection layer is formed on the layer a of the laminated film formed, an antireflection film excellent in all aspects of antireflection function, toughness and surface hardness can be obtained. It has been found that a polarizing plate having high hardness and excellent antireflection properties and antiglare properties can be obtained. The present invention has been completed based on this finding.

Thus, the present invention includes the following.
(1) A protective layer comprising at least a layer and a b layer containing a thermoplastic resin, wherein the bending elastic modulus of the a layer is larger than the bending elastic modulus of the b layer, and the a layer is present on the viewing side. A,
A polarizer and a protective layer B
Laminated at least in this order from the viewer side,
A polarizing plate having a haze of 10 to 60%.
(2) The polarizing plate according to (1), wherein a difference in flexural modulus between the a layer and the b layer is 0.2 GPa to 2.5 GPa.

(3) The polarizing plate according to any one of (1) and (2), wherein the protective layer A is obtained by a coextrusion method.
(4) The polarizing plate for liquid crystal display according to (1) or (2), wherein an antiglare layer is laminated directly or via another layer on the surface on the viewing side of the protective layer A.
(5) The polarizing plate for liquid crystal display according to (1) or (2), wherein an antiglare layer and an antireflection layer are laminated on the surface on the viewing side of the protective layer A directly or via another layer.
(6) The protective layer A is a polarizing plate for liquid crystal display according to any one of (1) to (5), which contains an ultraviolet absorber.
(7) The polarizing plate for liquid crystal displays according to any one of (1) to (6), wherein a surface on the viewing side of the protective layer A has an uneven shape.
(8) The polarizing plate according to any one of (1) to (7), which has a layer including a region where the refractive index is discontinuous, directly or via another layer, on the surface on the viewing side of the protective layer A .
(9) A liquid crystal display device comprising the polarizing plate according to any one of (1) to (8).

  The polarizing plate of the present invention is suitable for a liquid crystal display device because it is tough and has high surface hardness, excellent scratch resistance, and excellent antiglare properties.

Hereinafter, the present invention will be described in detail.
The polarizing plate of the present invention is formed by laminating a protective layer A, a polarizer, and a protective layer B at least in this order from the viewing side. There is no particular limitation on the method of laminating the protective layer A (the protective layer on the viewing side) and the protective layer B (the protective layer on the liquid crystal cell side) on the polarizer. For example, the protective film and the protective layer B that become the protective layer A What is necessary is just to employ | adopt the general method of laminating | stacking the protective film which becomes to a polarizer via an acrylic adhesive etc. as needed.
The polarizing plate of the present invention has a haze of 10 to 60%, preferably 30 to 60%. By having a haze in such a range, reflection can be prevented and antiglare properties can be improved. The method for adjusting the haze of the polarizing plate is not particularly limited, but a method for forming irregularities on the surface on the viewing side of the protective layer A, a method for laminating an antiglare layer, or the like, which will be a viewing side protective layer as described later, is applied. That's fine.

(1) Protective layer A
The protective layer A includes at least an a layer and a b layer containing a thermoplastic resin. Here, “the main component is a thermoplastic resin” means that the resin component constituting the a layer and the b layer is a thermoplastic resin and may contain a compounding agent or the like as desired. .

(I) a layer The thermoplastic resin contained in the a layer is not particularly limited as long as it is a highly transparent thermoplastic resin, but those having a light transmittance of 80% or more are preferable.

  Preferable specific examples of the thermoplastic resin contained in the layer a include vinyl aromatic polymers, polyacrylonitrile polymers, poly (meth) acrylate polymers, vinyl alicyclic hydrocarbon polymers and hydrides thereof. Can be mentioned. These can be used alone or in combination of two or more.

  Examples of the vinyl aromatic polymer include a copolymer of polystyrene, styrene and / or a styrene derivative and at least one selected from acrylonitrile, maleic anhydride, methyl methacrylate and butadiene; a copolymer of styrene and a conjugated diene Hydrides (including hydrides of aromatic rings); and the like. Here, examples of the styrene derivative include 4-methylstyrene, 3-methylstyrene, 4-chlorostyrene, 4-methoxystyrene, 4-tert-butoxystyrene, α-methylstyrene, and the like.

  Examples of the poly (meth) acrylate polymer include a homopolymer of a (meth) acrylate compound, two or more copolymers of a (meth) acrylate compound, a (meth) acrylate compound and other copolymers. Examples thereof include a copolymer with a polymerizable monomer. Here, (meth) acrylic acid ester means acrylic acid ester or methacrylic acid ester.

  Specific examples of the (meth) acrylic acid ester compound include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t -Butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, etc. are mentioned.

  Examples of the polyacrylonitrile-based polymer include acrylonitrile homopolymer, acrylonitrile, and a copolymer of acrylonitrile and a monomer copolymerizable with acrylonitrile. The monomer copolymerizable with acrylonitrile is selected from the group consisting of acrylic ester, methacrylic ester, styrene, vinyl acetate, glycidyl methacrylate, divinylbenzene, polyethylene glycol (n = 1-9) dimethacrylate. One or more of them.

  The vinyl alicyclic hydrocarbon polymer is a polymer having a repeating unit derived from vinylcycloalkane or vinylcycloalkene. Examples of the vinyl alicyclic hydrocarbon polymer include polymers of vinyl alicyclic hydrocarbon compounds such as vinyl cycloalkanes such as vinyl cyclohexane, vinyl cycloalkenes such as vinyl cyclohexene, and hydrides thereof; styrene, α-methyl Examples thereof include hydrides of aromatic ring portions of polymers of vinyl aromatic hydrocarbon compounds such as styrene.

  The vinyl alicyclic hydrocarbon polymer is a random copolymer of a vinyl alicyclic hydrocarbon compound or a vinyl aromatic hydrocarbon compound and another monomer copolymerizable with these monomers, It may be a copolymer such as a block copolymer and a hydride thereof. Examples of the block copolymerization include diblock, triblock, or more multiblock and gradient block copolymerization, but are not particularly limited.

  Preferred resins for layer a are vinyl aromatic polymers, poly (meth) acrylate polymers, vinyl alicyclic hydrocarbon polymers, and hydrides thereof, such as polystyrene, styrene / maleic acid copolymers, More preferred are methyl methacrylate, vinyl alicyclic hydrocarbon polymer and hydride thereof.

(Ii) b layer Although it will not restrict | limit especially if it is a highly transparent thermoplastic resin as a thermoplastic resin which comprises b layer, What has a light transmittance of 80% or more is preferable.

  Preferred specific examples of the resin constituting the layer b include alicyclic structure-containing polymers, cellulose polymers, polyester polymers, polycarbonate polymers, polysulfone polymers, polyethersulfone polymers, vinyl aromas. A group polymer, a polyolefin polymer, a polyvinyl alcohol polymer, a polyvinyl chloride polymer, and a poly (meth) acrylate polymer. These polymers can be used alone or in combination of two or more.

  Among these, alicyclic structure-containing polymers; cellulose polymers such as cellulose diacetate, cellulose triacetate, and cellulose acetate butyrate; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. Polyester-based polymers are preferable, and from the viewpoints of transparency, dimensional stability, lightness, and the like, alicyclic structure-containing polymers, cellulose triacetate, and polyethylene terephthalate are more preferable. From the viewpoint of low hygroscopicity and dimensional stability, alicyclic Formula structure containing polymers are particularly preferred.

  The alicyclic structure-containing polymer has an alicyclic structure in the repeating unit of the polymer, a polymer having an alicyclic structure in the main chain and a polymer having an alicyclic structure in the side chain. Any of these can be used.

  Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and a cycloalkane structure is preferable from the viewpoint of thermal stability. Although there is no restriction | limiting in particular in carbon number which comprises an alicyclic structure, Usually, 4-30 pieces, Preferably it is 5-20 pieces, More preferably, it is 5-15 pieces. When the number of carbon atoms constituting the alicyclic structure is in this range, a base resin film excellent in heat resistance and flexibility can be obtained.

  The proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer may be appropriately selected according to the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. If the number of repeating units having an alicyclic structure is too small, the heat resistance is undesirably lowered. In addition, repeating units other than the repeating unit which has an alicyclic structure in an alicyclic structure containing polymer are suitably selected according to the intended purpose.

  Specific examples of the alicyclic structure-containing polymer include a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, and hydrides thereof. Among these, norbornene-based polymers are preferable from the viewpoints of transparency and moldability.

  Specific examples of the norbornene-based polymer include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers capable of ring-opening copolymerization, and those Hydrides of the above, addition polymers of norbornene monomers, addition copolymers with other monomers copolymerizable with norbornene monomers, and the like. Among these, from the viewpoint of transparency, a ring-opening (co) polymer hydride of a norbornene monomer is particularly preferable.

Examples of the norbornene-based monomer include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene. (Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0. 1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene), derivatives of these compounds (for example, those having a substituent in the ring), and the like. Here, examples of the substituent include an alkyl group, an alkylene group, an alkoxycarbonyl group, and a carboxyl group. In addition, these substituents may be the same or different and a plurality may be bonded to the ring. Norbornene monomers can be used alone or in combination of two or more.

  Other monomers capable of ring-opening copolymerization with norbornene monomers include, for example, monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof; cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene; Derivatives thereof; and the like.

Ring-opening polymers of norbornene monomers and ring-opening copolymers of norbornene monomers and other monomers copolymerizable therewith are polymerized in the presence of a ring-opening polymerization catalyst. Can be obtained.
As the ring-opening polymerization catalyst, a commonly used known catalyst can be used.

  Examples of other monomers that can be addition-copolymerized with norbornene-based monomers include, for example, α-olefins having 2 to 20 carbon atoms such as ethylene and propylene, and derivatives thereof; cycloolefins such as cyclobutene and cyclopentene, and these Derivatives; non-conjugated dienes such as 1,4-hexadiene and the like. These monomers can be used alone or in combination of two or more. In these, an alpha olefin is preferable and ethylene is more preferable.

  Norbornene monomer addition polymers and addition copolymers of norbornene monomers and other monomers copolymerizable therewith are obtained by polymerizing the monomers in the presence of an addition polymerization catalyst. Obtainable. As the addition polymerization catalyst, a commonly used known catalyst can be used.

  Ring-opening polymer of norbornene monomer, ring-opening copolymer of norbornene monomer and other monomer capable of ring-opening copolymerization, addition polymer of norbornene monomer, and norbornene Addition of a known hydrogenation catalyst to the hydride of an addition polymer of a system monomer and another monomer copolymerizable therewith, preferably hydrogenates a carbon-carbon unsaturated bond by 90% or more. Can be obtained.

Examples of the monocyclic olefin-based polymer include addition polymers such as cyclohexene, cycloheptene, and cyclooctene.
Examples of the cyclic conjugated diene polymer include polymers obtained by 1,2-addition polymerization or 1,4-addition polymerization of cyclic conjugated diene monomers such as cyclopentadiene and cyclohexadiene.

  The molecular weight of the thermoplastic resin constituting the a layer and the b layer is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography using cyclohexane (toluene when the polymer resin is not dissolved) as a solvent. The range is usually 10,000 to 300,000, preferably 15,000 to 250,000, more preferably 20,000 to 200,000. When the molecular weight is in such a range, when the protective film to be the protective layer A is produced, the mechanical strength and moldability of the film are highly balanced and suitable.

  Although the glass transition temperature of the thermoplastic resin which comprises the said a layer and b layer should just be selected suitably according to a use purpose, Preferably it is 80 degreeC or more, More preferably, it is the range of 100-250 degreeC. When the protective film A is produced when the glass transition temperature is in such a range, it is possible to obtain a film having excellent durability without causing deformation and stress in use under high temperature and high humidity. it can.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the thermoplastic resin constituting the a layer and the b layer is not particularly limited, but is usually 1.0 to 10.0, preferably 1.0. It is -6.0, More preferably, it is the range of 1.1-4.0. By adjusting the molecular weight distribution in such a range, when a protective film to be the protective layer A is produced, a film in which mechanical strength and moldability are well balanced can be obtained.

(Flexural modulus)
The protective layer A includes at least an a layer and a b layer mainly composed of a thermoplastic resin, and the bending elastic modulus of the a layer is larger than the bending elastic modulus of the b layer.

  The flexural modulus is a ratio of a load and a deflection when a bending load is applied to an object. More specifically, the strains at two specified points are ε1 and ε2, and the corresponding stresses are ρ1 and ρ2. The stress difference (ρ2−ρ1) is divided by the strain difference (ε2−ε1).

  Generally, a tough polymer has a low flexural modulus, and a polymer with a high surface hardness has a high flexural modulus. As the protective layer A, a layer formed by combining a layer having a relatively high flexural modulus and high surface hardness and a layer b having a relatively small flexural modulus and excellent toughness, and the layer a By disposing on the viewer side of the b layer, the protective layer A is tough and has a high surface hardness.

  The bending elastic modulus of the a layer may be any relatively larger than the bending elastic modulus of the b layer. However, in order to obtain a tougher polarizing plate with higher surface hardness, the bending elastic modulus of the a layer is 3 GPa. As described above, it is preferably 3 to 4 GPa, and the flexural modulus of the b layer is less than 3 GPa, preferably 0.1 to 3 GPa. When the flexural modulus of the a layer exceeds 4 GPa, the opacity or melt viscosity becomes high, and film formation may be difficult. Moreover, when the bending elastic modulus of b layer will be less than 0.1 GPa, the viscosity at the time of a fusion | melting will become low, and there exists a possibility that film forming may become difficult.

  The difference in bending elastic modulus between the a layer and the b layer is not particularly limited as long as the bending elastic modulus of the a layer is relatively larger than the bending elastic modulus of the b layer, but is preferably 0.2 to 2.5 GPa. More preferably, it is 0.5 to 2.0 GPa. If the difference in flexural modulus between the a layer and the b layer is too small, the balance between toughness and surface hardness of the resulting polarizing plate may be deteriorated. On the other hand, if the difference in flexural modulus is too large, it may be difficult to form a uniform laminated film during film formation.

  As a preferred combination of the a layer and the b layer, moisture permeability, toughness, and surface hardness are highly balanced, and therefore, expressed as a layer / b layer, containing a vinyl aromatic polymer / alicyclic structure Examples thereof include polymers and poly (meth) acrylate polymers / alicyclic structure-containing polymers. Of these, combinations of polystyrene / alicyclic structure-containing polymer, styrene / maleic acid copolymer / alicyclic structure-containing polymer, and polymethyl methacrylate / alicyclic structure-containing polymer are particularly preferable.

  The protective layer A may be a laminate including at least an a layer and a b layer. However, the protective layer A further includes a c layer on the opposite side of the a layer via the b layer, or between the a layer and the b layer. If desired, it may be laminated via an x layer.

  The c layer is provided to prevent curling of the antireflection film, and can be formed of a material having affinity for both the resin constituting the a layer and the resin constituting the b layer. For example, what consists of a thermoplastic resin with high transparency and affinity to both resin which comprises a layer and b layer is mentioned. Moreover, c layer can also be formed from the same resin as a layer or b layer.

  Although c layer is provided in order to prevent curling of the protective film used as the protective layer A, curl cannot be prevented even if the thickness is too thin or too thick. The thickness of c layer is 5-100 micrometers normally, Preferably it is 10-50 micrometers.

  The x layer can be formed from a resin having an affinity for both the resin constituting the a layer and the b layer. For example, polyester urethane resin, polyether urethane resin, polyisocyanate resin, polyolefin copolymer, resin having a hydrocarbon skeleton in the main chain, polyamide resin, acrylic resin, vinyl chloride-vinyl acetate copolymer, Examples thereof include chlorinated rubber, cyclized rubber, and modified products obtained by introducing polar groups into these polymers. Among these, polyolefin copolymers and modified products thereof are preferably used.

  Examples of polyolefin copolymers include ethylene- (meth) acrylic acid ester copolymers such as ethylene- (meth) methyl acrylate copolymer and ethylene- (meth) ethyl acrylate copolymer; ethylene and (meth) A terpolymer obtained by copolymerizing an acrylic ester with another copolymerizable monomer (propylene, maleic acid, vinyl acetate, etc.); ethylene-vinyl acetate copolymer; ethylene-styrene copolymer; And ethylene- (meth) acrylic acid glycidyl ester copolymer;

  Examples of the method for introducing a polar group into these polyolefin copolymers include oxidation, saponification, chlorination, chlorosulfonation, addition of unsaturated carboxylic acid, and the like. Of these, unsaturated carboxylic acid addition is preferably used.

  Examples of the resin having a hydrocarbon skeleton in the main chain include a polybutadiene skeleton or a resin having a polybutadiene skeleton hydrogenated to at least a part thereof, specifically, polybutadiene resin, hydrogenated polybutadiene resin, styrene / butadiene / styrene. Examples thereof include a block copolymer (SBS copolymer), a hydrogenated product thereof (SESB copolymer), and the like. Among them, a modified product of a hydrogenated product of styrene / butadiene / styrene block copolymer is preferable.

  As a compound for introducing a polar group used for obtaining a modified product of these polymers, a carboxylic acid or a derivative thereof is preferable. For example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid; halides, amides, imides, anhydrides and esters of unsaturated carboxylic acids such as maleyl chloride, maleimide, maleic anhydride and citraconic anhydride And the like; and the like. Among these, a modified product with an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride is excellent in adhesion, and thus can be suitably used. Among the unsaturated carboxylic acids or anhydrides thereof, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are more preferable, and maleic acid and maleic anhydride are particularly preferable. These unsaturated carboxylic acids and the like can be modified by mixing two or more kinds.

  The method for producing the protective layer A is not particularly limited. For example, (i) a method in which an a layer and a b layer are separately formed and laminated by dry lamination via an x layer to form a laminate (ii) ) A method of forming a film by coextrusion to obtain a laminate. Of these, the coextrusion method (ii) is preferred because a laminate having a high delamination strength can be obtained and the production efficiency is excellent. Specifically, a method of obtaining a laminate by a coextrusion method is to form a film by extruding a resin material constituting the a layer and a resin material constituting the b layer from a multilayer die using a plurality of extruders. Is.

In the case of co-extrusion, the compounding agent can be added to the a layer, the b layer and / or the c layer as long as the object of the present invention is not impaired.
The compounding agent to be used is not particularly limited. For example, a lubricant; a layered crystal compound; an inorganic fine particle; a stabilizer such as an antioxidant, a heat stabilizer, a light stabilizer, a weather stabilizer, an ultraviolet absorber, a near infrared absorber; Plasticizers; coloring agents such as dyes and pigments; antistatic agents; These compounding agents can be used alone or in combination of two or more. The compounding quantity of a compounding agent can be suitably determined in the range which does not impair the objective of this invention.

  Lubricants include inorganic particles such as silicon dioxide, titanium dioxide, magnesium oxide, calcium carbonate, magnesium carbonate, barium sulfate, and strontium sulfate, as well as polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, polystyrene, cellulose acetate, and cellulose Organic particles such as acetate propionate can be mentioned. As particles constituting the lubricant, organic particles are preferable, and among these, particles made of polymethyl methacrylate are particularly preferable.

By using elastic particles made of a rubber-like elastic body as a lubricant, flexibility can be imparted. Examples of the rubber-like elastic body include an acrylate-based rubber-like polymer, a rubber-like polymer containing butadiene as a main component, and an ethylene-vinyl acetate copolymer. Examples of the acrylic ester rubbery polymer include those containing butyl acrylate, 2-ethylhexyl acrylate, or the like as a main component. Of these, acrylate polymers based on butyl acrylate and rubbery polymers based on butadiene are preferred.
The elastic particles may be formed by laminating two kinds of polymers. Typical examples thereof include an alkyl acrylate such as butyl acrylate, a styrene grafted rubber elastic component, and a methyl methacrylate. Examples thereof include elastic particles in which a hard resin layer made of a copolymer of a rate and / or methyl methacrylate and an alkyl acrylate forms a layer with a core-shell structure.

  The elastic particles generally have a number average particle size of 2.0 μm or less, preferably 0.1 to 1.0 μm, and more preferably 0.1 to 0.5 μm when dispersed in a thermoplastic resin. Even if the primary particle diameter of the elastic particles is small, if the number average particle diameter of the secondary particles formed by aggregation or the like is large, the protective layer A has a high haze (cloudiness) and a low light transmittance. , Not suitable for display screen. Moreover, when the number average particle size becomes too small, the flexibility tends to decrease.

  The total thickness of the protective layer A obtained is usually 30 to 200 μm, preferably 40 to 150 μm, particularly preferably 50 to 100 μm.

  Moreover, the thickness of the a layer contained in the protective layer A is 5-100 micrometers normally, Preferably it is 10-50 micrometers. If the thickness of the a layer is less than 5 μm, the surface hardness cannot be increased. On the other hand, when the thickness is greater than 100 μm, the protective layer A becomes brittle, which is not preferable.

  The thickness of b layer is 5-100 micrometers normally, Preferably it is 10-50 micrometers. If the thickness of the b layer is less than 5 μm, the protective layer A becomes brittle, which is not preferable. On the other hand, if the thickness is greater than 100 μm, the transparency of the protective layer A may be reduced. In addition, the thickness of the entire polarizing plate increases, which may hinder the miniaturization of the display.

  When the protective layer A has an x layer, the thickness of the x layer is usually 1 to 20 μm, preferably 1 to 10 μm, more preferably 2 to 7 μm. If the thickness of the x layer is greater than 20 μm, the surface hardness may not be increased.

In the polarizing plate of the present invention, the protective layer A preferably has a low moisture permeability. As will be described later, the polarizer has the property of absorbing moisture in the air and gradually decreasing the degree of polarization. Therefore, by attaching a protective layer A having a low moisture permeability to the polarizer, polarized light with excellent durability. A board can be obtained.
The moisture permeability can be measured by a method based on JIS Z 0208.

  Further, as the protective layer A, one having one or both surfaces subjected to surface modification treatment can be used. By performing the surface modification treatment, adhesion to the low refractive index layer and other layers described later can be improved. Examples of the surface modification treatment include energy beam irradiation treatment and chemical treatment.

  Examples of the energy ray irradiation treatment include corona discharge treatment, plasma treatment, electron beam irradiation treatment, ultraviolet ray irradiation treatment, and the like. From the viewpoint of treatment efficiency, corona discharge treatment and plasma treatment are preferred, and corona discharge treatment is particularly preferred. Examples of the chemical treatment include a method of immersing in an aqueous oxidizing agent solution such as a potassium dichromate solution or concentrated sulfuric acid and then thoroughly washing with water. In chemical treatment, it is effective to shake in an immersed state, but there is a problem that the surface dissolves or transparency decreases when treated for a long time, depending on the reactivity, concentration, etc. of the chemical used, It is necessary to adjust the processing time.

  As the layer structure of the protective layer A, a protective layer A that is tough and excellent in surface hardness is obtained. Therefore, the protective layer A having a three-layer structure of a layer-x layer-b layer, a layer-x layer-b layer The protective layer A having a five-layer structure of -x layer-a layer is preferable.

  In order to adjust the haze value of the polarizing plate of the present invention, an appropriate antiglare means can be provided on the outer surface of the protective layer A. As anti-glare means, for example, (a) a fine unevenness is formed on the viewing side to cause light scattering, and (b) a layer composed of two or more components having a difference in refractive index is formed on the viewing side. As a result, there are those that cause light scattering due to a difference in refractive index.

(Anti-glare means)
The method for forming fine irregularities is not particularly limited, and an appropriate method can be adopted. For example, in a state in which the protective layer A is directly or in a state where other layers are laminated, the unevenness is transferred by a method of imparting fine unevenness by a method of roughening by a method such as sandblasting, embossing roll, chemical etching, or a shaping film. In addition to methods (for example, JP-A-2005-331901), a method of dispersing fine particles in a resin constituting the protective layer, and a method of forming an antiglare layer made of a transparent resin material containing fine particles on the protective layer A (Japanese Patent Laid-Open No. 11-305010, Japanese Patent Laid-Open No. 2002-107512, Japanese Patent Laid-Open No. 10-246802, etc.). These methods may be used in combination of two or more.
In addition, the degree of unevenness is not particularly limited as long as the haze value is in the above range. Usually, the center line average roughness (Ra) is 0.04 to 0.5 μm, and the average peak-to-valley spacing (Sm) is 20 to 100 μm. It is.

  As the transparent resin material used for forming the antiglare layer, fine particles can be dispersed, sufficient strength as a film can be given, and a transparent material can be used without particular limitation. Examples of the resin include thermosetting resins, thermoplastic resins, ultraviolet curable resins, and electron beam curable resins. Among these, an ultraviolet curable resin that can efficiently form an antiglare layer by a simple processing operation by a curing treatment by ultraviolet irradiation is preferable.

  Examples of the ultraviolet curable resin include various types such as polyester, acrylic, urethane, amide, silicone, and epoxy, and these include ultraviolet curable monomers, oligomers, polymers, and the like. Examples of the ultraviolet curable resin preferably used include those having an ultraviolet polymerizable functional group, particularly those containing an acrylic monomer or oligomer having 2 or more, particularly 3 to 6 functional groups.

Further, the transparent resin material may contain 10 parts by weight or more and 100 parts by weight or less of solvent-drying resin with respect to 100 parts by weight of the resin. As the solvent-drying resin, a thermoplastic resin is mainly used.
In particular, when a mixture of polyester acrylate and polyurethane acrylate is used as the ionizing radiation curable resin, polymethyl methacrylate, polybutyl methacrylate, or cellulose acetate propionate is preferably used as the solvent-drying resin.

  The fine particles may be inorganic fine particles or organic fine particles, or may be modified fine particles such as those obtained by coating inorganic fine particles with an organic material. For example, fine particles that exhibit a diffusion effect due to a difference in refractive index with the transparent resin material and fine particles that exhibit a diffusion effect by forming irregularities on the surface of the resin layer can be used in combination.

  The shape of the fine particles may be a true sphere, an ellipse or the like, preferably a true sphere. Examples of the inorganic fine particles include silica and alumina. The organic fine particles are preferably resin beads having a refractive index of 1.40 to 1.60. Resin beads include polymethyl methacrylate beads (refractive index: 1.49), melamine beads (refractive index 1.57), polycarbonate beads (refractive index: 1.58), polystyrene beads (refractive index: 1.60). And acrylic styrene resin beads (refractive index: 1.57), polyvinyl chloride beads (refractive index: 1.54), and polyethylene beads.

  These resin beads preferably have a particle diameter of 1 to 8 μm, and are used in an amount of 5 to 22 parts by weight, preferably 10 to 25 parts by weight, based on 100 parts by weight of the resin. When such resin beads are mixed, the resin beads precipitated on the bottom of the container at the time of coating need to be stirred and dispersed well. In order to eliminate such inconvenience, silica beads having a particle diameter of 0.5 μm or less, preferably 0.1 to 0.25 μm may be included in the coating liquid as an anti-settling agent for resin beads. The more silica beads are added, the more effective the prevention of sedimentation of the resin beads is, but it adversely affects the transparency of the coating film. Therefore, the amount of the anti-settling agent is preferably less than 0.1 parts by weight with respect to 100 parts by weight of the resin, to the extent that the transparency as the antiglare layer is not impaired.

  The fine particles may exist in a uniformly dispersed form in the cured film or may be unevenly distributed in the film thickness direction. The fine particles may be present in a form protruding from the surface. However, from the viewpoint of improving the clarity of the transmitted image described later, the fine particles protruding from the surface of the antiglare layer is preferably 0.5 μm or less. .

  The transparent resin material for forming the antiglare layer may contain other materials such as an antistatic agent, a leveling agent, and an ultraviolet absorber as necessary.

  As a method for forming an antiglare function by internal scattering by forming a layer including a region where the refractive index is discontinuous, two or more kinds of compositions having different refractive indexes are used to form a phase separation structure by ultraviolet irradiation or the like. And a method of forming a layer containing fine particles having a refractive index different from that of the transparent resin material and the transparent resin material.

  As a method for forming a layer having a phase separation structure, for example, a known method such as a method described in Japanese Patent No. 3446737 using two kinds of photopolymerizable monomers and / or oligomers can be employed.

  Examples of these photopolymerizable monomers and oligomers include 2,4,6-tribromophenyl acrylate, tribromophenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, tetrahydrofurfuryl acrylate, ethyl carbitol acrylate Pentenyloxyethyl acrylate, phenyl carbitol acrylate, polyol polyacrylate, isocyanuric acid skeleton polyacrylate, melamine acrylate, hydantoin skeleton polyacrylate, urethane acrylate, and the like.

  Two or more kinds of the above photopolymerizable monomers and oligomers having different refractive indexes are used. Examples of the combination include two types selected from monomers, one type of monomer and one type of oligomer, two types selected from oligomers, or a combination of these in addition to one or more types of monomers or oligomers. In these combinations, it is preferable that at least two of them have a refractive index difference of 0.03 or more in order to obtain a necessary light scattering ability.

  Furthermore, it is preferable to use a photopolymerization initiator in order to improve the curability of the composition containing the materials having different refractive indexes. Examples of the photopolymerization initiator include benzophenone, 2-hydroxy-2-methylpropiophenone, benzyl, Michler's ketone, and 2-chlorothioxanthone as exemplified in JP-A-7-64069.

  A composition containing a material having a different refractive index can contain a compound having a refractive index different from that of a photopolymerizable monomer or oligomer and having no photopolymerizability. Examples include styrene resins such as polystyrene, acrylic resins such as polymethyl methacrylate, resins such as polyethylene oxide, polyvinyl pyrrolidone, and polyvinyl alcohol, and plastic additives such as organic halogen compounds, organic silicon compounds, plasticizers, and stabilizers. It is done. These can also be mix | blended in said composition as a high refractive index component or a low refractive index component. The difference in refractive index between the photopolymerizable monomer or oligomer and the non-photopolymerizable compound is preferably 0.03 or more.

  Furthermore, 0.01 to 5 parts by weight of a filler having an average particle diameter of 0.05 to 20 μm can be blended, or an ultraviolet absorber can be added.

  The transparent resin material for forming the antiglare layer utilizing the scattering phenomenon caused by the difference in refractive index between the transparent resin material and the fine particles can be selected from those exemplified as the transparent resin material constituting the fine uneven layer.

  In order to obtain an antiglare effect due to the difference in refractive index between the transparent resin material and the fine particles, the difference between the refractive index of the transparent resin material and the refractive index of the fine particles is preferably 0.03 or more, more preferably 0.04. It is 0.5 or less. When the difference in refractive index is less than 0.03, the light diffusion effect cannot be obtained. When the difference in refractive index is greater than 0.5, the light diffusibility is too strong and the image sharpness is deteriorated.

  The film thickness (when cured) of the antiglare layer is 0.1 to 20 μm, preferably 0.8 to 10 μm. When the film thickness is within this range, the function as an antiglare layer can be sufficiently exhibited.

  In addition, when forming the anti-glare layer by a cured film on the said transparent base material, a hydrophilic treatment can be given to the surface of a transparent base material. The hydrophilic treatment means is not particularly limited, and for example, a surface treatment method such as corona discharge treatment, sputtering treatment, low-pressure UV irradiation, or plasma treatment can be suitably employed. Moreover, the process which improves adhesiveness, such as a thin-layer application | coating process of a cellulose-type material and a polyester-type material, can be given.

  Furthermore, in the polarizing plate of the present invention, functional layers such as a hard coat layer, an antireflection layer, and an antifouling layer may be formed on the outer surface of the protective layer A.

(Hard coat layer)
The hard coat layer is preferably formed of a heat or photo-curing material that exhibits a hardness of “1H” or higher in a pencil hardness test (test plate is a glass plate) shown in JIS K5600-5-4. The pencil hardness of the protective layer A provided with the hard coat layer is preferably 4H or more. When the surface layer of the protective layer A is made of an acrylic resin, the hard coat layer makes it easy to adjust the surface pencil strength to 4H or higher.

  Examples of the hard coat layer material include organic hard coat materials such as organic silicone, melamine, epoxy, acrylic, and urethane acrylate; and inorganic hard coat materials such as silicon dioxide. Of these, urethane acrylate-based and polyfunctional acrylate-based hard coat materials are preferably used from the viewpoint of good adhesive strength and excellent productivity.

  This hard coat layer has a refractive index nH between the refractive index nL of the low refractive index layer laminated thereon, nH ≧ 1.53, and nH1 / 2−0.2 <nL <nH1 / 2 + 0. .2 is preferable for exhibiting the antireflection function.

  This hard coat layer contains various fillers for the purpose of adjusting the refractive index, improving the flexural modulus, stabilizing the volume shrinkage, improving heat resistance, antistatic properties, antiglare properties, etc., as desired. You may squeeze it. Furthermore, various additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, and an antifoaming agent can be blended.

(Antireflection layer)
When using the polarizing plate of this invention for the display screen of a display, for example, it is preferable that the antireflection layer is further laminated | stacked on the said hard-coat layer. The antireflection layer is a layer for preventing the transfer of external light. The polarizing plate on which such an antireflection layer is laminated preferably has a reflectance at an incident angle of 5 ° and 430 to 700 nm of 2.0% or less and a reflectance at 550 nm of 1.0% or less. . The thickness of the antireflection layer is preferably 0.01 μm to 1 μm, and more preferably 0.02 μm to 0.5 μm. Examples of such an antireflection layer include those obtained by laminating a low refractive index layer having a refractive index smaller than that of the hard coat layer, preferably a refractive index of 1.30 to 1.45, and a low Examples thereof include those obtained by repeatedly laminating a refractive index layer and a high refractive index layer made of an inorganic compound.

  The material for forming the low refractive index layer is not particularly limited as long as it has a refractive index lower than that of the base material or the hard coat layer. For example, a resin material such as an ultraviolet curable acrylic resin, or colloidal silica in the resin. Examples thereof include hybrid materials in which inorganic fine particles such as sol are dispersed, and sol-gel materials using metal alkoxides such as tetraethoxysilane. The material for forming the exemplified low refractive index layer may be a polymerized polymer, or a monomer or oligomer serving as a precursor. Moreover, it is preferable that each material contains the compound containing a fluorine group in order to provide the surface antifouling property.

Examples of the sol-gel material containing a fluorine group include perfluoroalkylalkoxysilane. As perfluoroalkyl alkoxysilane, for example, general formula: CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃ (wherein R represents an alkyl group having 1 to 5 carbon atoms, n is And an integer of 0 to 12). Specifically, for example, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltri And ethoxysilane. Among these, the compound wherein n is 2 to 6 is preferable.

  The low refractive index layer is preferably made of a cured product of a thermosetting fluorine-containing compound or an ionizing radiation curable fluorine compound. The dynamic friction coefficient of the cured product is preferably 0.03 to 0.15, and the contact angle with water is preferably 90 to 120 degrees. Examples of the curable fluorine-containing polymer compound include a perfluoroalkyl group-containing silane compound (for example, (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane) and the like, and a fluorine-containing fluorine-containing polymer having a crosslinkable functional group. A copolymer is mentioned.

  The fluorine-containing polymer having a crosslinkable functional group is obtained by copolymerizing a fluorine-containing monomer and a monomer having a crosslinkable functional group, or by copolymerizing a fluorine-containing monomer and a monomer having a functional group, and then in the polymer. It can be obtained by adding a compound having a crosslinkable functional group to the functional group.

  Fluoroolefins such as fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole; biscoat 6FM (Osaka Organic) Chemical), M-2020 (manufactured by Daikin), (meth) acrylic acid partial or fully fluorinated alkyl ester derivatives, fully or partially fluorinated vinyl ethers, and the like.

  Monomers having a crosslinkable functional group or compounds having a crosslinkable functional group include monomers having a glycidyl group such as glycidyl acrylate and glycidyl methacrylate; monomers having a carboxyl group such as acrylic acid and methacrylic acid; hydroxyalkyl acrylate and hydroxyalkyl Monomers having a hydroxyl group such as methacrylate; methylol acrylate, methylol methacrylate; monomers having a vinyl group such as allyl acrylate and allyl methacrylate; monomers having an amino group; monomers having a sulfonic acid group;

  As a material for forming the low refractive index layer, a material containing a sol in which fine particles such as silica, alumina, titania, zirconia, magnesium fluoride and the like are dispersed in an alcohol solvent is used because it can improve scratch resistance. Can do. From the viewpoint of antireflection properties, the fine particles preferably have a lower refractive index. Such fine particles may have voids, and silica hollow fine particles are particularly preferable. The average particle size of the hollow fine particles is preferably 5 nm to 2,000 nm, and more preferably 20 nm to 100 nm. Here, the average particle diameter is a number average particle diameter obtained by observation with a transmission electron microscope.

  The thickness of the low refractive index layer is not particularly limited, but is preferably about 0.05 to 0.3 μm, particularly preferably 0.1 to 0.3 μm.

(Anti-fouling layer)
In order to improve the antifouling property of the low refractive index layer, an antifouling layer may be further provided on the low refractive index layer (observation side). The antifouling layer is a layer that can impart water repellency, oil repellency, sweat resistance, antifouling properties and the like to the surface. As a material used for forming the antifouling layer, a fluorine-containing organic compound is suitable. Examples of the fluorine-containing organic compound include fluorocarbon, perfluorosilane, or a polymer compound thereof. As a method for forming the antifouling layer, a physical vapor deposition method such as vapor deposition or sputtering, a chemical vapor deposition method, a wet coating method, or the like can be used depending on the material to be formed. The average thickness of the antifouling layer is preferably 1 to 50 nm, more preferably 3 to 35 nm.

  In addition to these layers, other layers such as a gas barrier layer, a transparent antistatic layer, a primer layer, an electromagnetic shielding layer, and an undercoat layer may be provided on the protective layer A.

When the functional layer as described above is formed, it is preferable to perform chemical treatment on the surface to be formed. Examples of the chemical treatment include corona discharge treatment, sputtering treatment, low-pressure UV irradiation treatment, and plasma treatment. In addition to the chemical treatment, the protective layer A of the present invention is subjected to mechanical treatment such as etching, sandblasting, embossing roll, etc. for the purpose of enhancing adhesion with the functional layer and imparting antiglare properties. Also good.
There is no particular limitation on the method for forming these functional layers, and a general method may be employed for forming each functional layer.

(Polarizer)
The polarizer used in the present invention is not particularly limited as long as it has a function as a polarizer. For example, a polyvinyl alcohol (PVA) type or polyene type polarizer can be used.
The manufacturing method of a polarizer is not specifically limited. As a method for producing a PVA polarizer, a method of stretching uniaxially after adsorbing iodine ions on a PVA film, a method of adsorbing iodine ions after stretching a uniaxially stretched PVA film, A method of simultaneously performing iodine ion adsorption and uniaxial stretching, a method of stretching a uniaxial film after dyeing a PVA film with a dichroic dye, a method of stretching a uniaxial film and then adsorbing with a dichroic dye, a PVA system The method of performing simultaneously dyeing | staining with a dichroic dye and uniaxial stretching to a film is mentioned. In addition, as a method for producing a polyene-based polarizer, a method of heating and dehydrating in the presence of a dehydration catalyst after stretching a PVA film uniaxially, a method of stretching a polyvinyl chloride film uniaxially and then in the presence of a dehydrochlorination catalyst And publicly known methods such as heating and dehydrating.

(Aligned with rubber uneven distribution)
(Protective layer B)
The protective layer B used in the present invention may be the same as the protective layer A described above, or may be a protective layer conventionally used for polarizing plates. The protective layer B is preferably formed of a material having a light transmittance in the visible region of 400 to 700 nm at a thickness of 1 mm of 80% or more, more preferably 85% or more, and still more preferably 90% or more. As the resin constituting the protective layer conventionally used for polarizing plates, polycarbonate resin, polyethersulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polystyrene Examples thereof include resins, polyvinyl chloride resins, cellulose esters, and alicyclic olefin polymers. Examples of the alicyclic olefin polymer include cyclic olefin random multi-component copolymers described in JP-A No. 05-310845 or US Pat. No. 5,179,171, JP-A No. 05-97978 or US Pat. No. 5,202,388. Examples thereof include the hydrogenated polymers described, thermoplastic dicyclopentadiene ring-opening polymers described in JP-A No. 11-124429 (WO 99/20676), and hydrogenated products thereof. .

  The polarizing plate of the present invention may be obtained by laminating a film showing birefringence on the protective layer B side in addition to the protective layer A, the polarizer and the protective layer B described above. In this case, the protective layer B is preferably optically isotropic. Specifically, Re is preferably 10 nm or less, more preferably 5 nm or less. The absolute value of Rth is preferably 10 nm or less, more preferably 5 nm or less.

A film showing birefringence may be used as the protective layer B.
When a film showing birefringence is used as the protective layer B, or when a film showing birefringence is laminated on the protective layer B side, it has a function of optical compensation such as color compensation, viewing angle compensation, etc. The visibility of the display device is improved.

  Birefringent films include those obtained by stretching a film containing a thermoplastic resin, those obtained by forming an optically anisotropic layer on an unstretched thermoplastic resin film, and optical on a film containing a thermoplastic resin. After forming the anisotropic layer, it can be further stretched. The film showing birefringence may be a single layer film or a laminated film.

<A stretched film containing a thermoplastic resin>
The thermoplastic resin used for obtaining a film exhibiting birefringence can be selected from those exemplified as the resin constituting the protective layer B. Of these, alicyclic olefin polymers and cellulose esters are preferred because of their excellent transparency, low birefringence, dimensional stability, and the like. A retardation increasing agent can be added to these resins as needed.

  As a method of stretching the film containing the thermoplastic resin, a uniaxial stretching method such as a method of stretching uniaxially in a transverse direction using a tenter; a gap between fixed clips is opened and a guide rail spreads simultaneously with stretching in the longitudinal direction. Simultaneous biaxial stretching method that stretches in the transverse direction depending on the angle, or sequential stretching that stretches in the longitudinal direction using the difference in peripheral speed between rolls and then grips both ends of the clip and stretches in the transverse direction using a tenter. Biaxial stretching method such as axial stretching method; Tenter stretching machine that can add feed force, pulling force or pulling force at different speeds in the horizontal or vertical direction; Alternatively, using a tenter stretching machine that can add a pulling force or a pulling force so that the moving distance is the same and the stretching angle θ can be fixed, or the moving distance is different. How to order stretching: and the like.

  Stretching can usually be performed in the range of Tg to Tg + 20 ° C., where Tg is the glass transition temperature of the resin forming the protective layer B, particularly the resin having the lowest glass transition temperature. Moreover, what is necessary is just to adjust a draw ratio in order to obtain a desired optical characteristic in the range of 1.1 to 3.0 times normally.

<Those formed with an optically anisotropic layer on an unstretched thermoplastic resin film>
For the formation of the optically anisotropic layer, a polymer compound or a liquid crystal compound can be used. These may be used alone or in combination.

  As the polymer compound, polyamide, polyimide, polyester, polyether ketone and the like can be used. Specific examples include compounds described in JP-T-8-511812 (International Publication No. WO94 / 24191) and JP-T 2000-511296 (International Publication No. WO97 / 44704).

  Further, the liquid crystalline compound may be a rod-like liquid crystal or a discotic liquid crystal, and these include a polymer liquid crystal or a low-molecular liquid crystal, and those in which a low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity. . Preferable examples of the rod-like liquid crystal include those described in JP 2000-304932A. Preferred examples of the discotic liquid crystal include those described in JP-A-8-50206.

  The optically anisotropic layer is generally formed by applying a solution of a discotic compound and other compounds (eg, plasticizer, surfactant, polymer, etc.) dissolved in a solvent onto the alignment film, drying, and then discotic nematic. It can be obtained by heating to the phase formation temperature and then cooling while maintaining the orientation state (discotic nematic phase). Alternatively, the optically anisotropic layer may be formed by applying a solution obtained by dissolving a discotic compound and another compound (for example, a polymerizable monomer, a photopolymerization initiator) in a solvent onto the alignment film, drying, and then discotic It can be obtained by heating to a nematic phase formation temperature, followed by polymerization by irradiation with UV light, etc., and further cooling.

  The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 0.7 to 5 μm. However, depending on the mode of the liquid crystal cell, it may be thickened (3 to 10 μm) in order to obtain high optical anisotropy. The method for forming the optically anisotropic layer is not particularly limited. For example, the polymer compound and / or liquid crystal compound is applied to a film containing a thermoplastic resin to produce a coating film, It can be produced by further stretching or shrinking the coating film.

The haze of the polarizing plate of the present invention obtained by laminating the above-mentioned layers is 10 to 60%, preferably 10 to 50%, and the total light transmittance of the polarizing plate is usually 25 to 50%, preferably 30 to 30%. 50%, more preferably 35-50%.
The total light transmittance of the protective layer A constituting the polarizing plate is preferably 70 to 100%, more preferably 80 to 100%, still more preferably 85 to 100% (for example, 85 to 95%), particularly preferably. Is about 90 to 100% (for example, 92 to 99%).

  The haze and total light transmittance can be measured using a haze meter “NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd. When measuring haze and total light transmittance, a protective layer having a haze of 0.1% or less and a total light transmittance of 85% or more was formed on the surface of the polarizer where the protective layer according to the present invention was not formed. Use things.

In the preferred polarizing plate of the present invention, the protective layer A is laminated with the first thermoplastic resin layer facing the polarizer, and the first thermoplastic resin layer has a range of 380 nm to 780 nm. The refractive index n ₁ (λ) at the wavelength and the refractive index n _b (λ) at a wavelength in the range of 380 nm to 780 nm of polyvinyl alcohol satisfy the relationship of the formula [1].
| N ₁ (λ) −n _b (λ) | ≦ 0.05 Formula [1]

In the preferred polarizing plate of the present invention, the first thermoplastic resin layer of the protective layer A is laminated facing the polarizer side, and the refractive index of the first thermoplastic resin layer at a wavelength of 380 nm. n ₁ (380) and a refractive index n ₁ (780) at a wavelength of 780 nm, and a refractive index n _b (380) at a wavelength of 380 nm and a refractive index n _b (780) at a wavelength of 780 nm of the polyvinyl alcohol contained in the polarizer. Satisfy the relationship of the formula [2].
|| n ₁ (380) −n _b (380) |
− | N ₁ (780) −n _b (780) || ≦ 0.02 Formula [2]

That is, the difference between the refractive index of the first thermoplastic resin layer at a wavelength near the upper limit of the visible light region and the refractive index of polyvinyl alcohol contained in the polarizer is not so different from the difference at the wavelength near the lower limit. That's what it means. In particular, it is preferable that || n ₁ (380) −n _b (380) | — | n ₁ (780) −n _b (780) || ≦ 0.01. Note that n ₁ (380) and n ₁ (780) are average values of the main refractive indices at the respective wavelengths. n _b (380) and n _b (780) are the refractive indices of non-oriented polyvinyl alcohol.

  The polarizing plate of the present invention preferably exhibits a hardness of “3H” or higher, more preferably a hardness of “4H” or higher, in a pencil hardness test (test plate is a glass plate) shown in JIS K5600-5-4.

<Liquid crystal display device>
The liquid crystal display device of the present invention can be manufactured using the polarizing plate of the present invention. In the liquid crystal display device, a light source, an incident side polarizing plate, a liquid crystal cell, and an output side polarizing plate are usually arranged in this order. The polarizing plate of the present invention is provided on the emission side (viewing side) of the device. The liquid crystal display device of the present invention may further include a retardation plate, a brightness enhancement film, a light guide plate, a light diffusion plate, a light diffusion sheet, a light collection sheet, a reflection plate, and the like.

The present invention will be described in more detail with reference to examples and comparative examples. Parts and% are based on mass unless otherwise specified.
The protective films obtained in Examples and Comparative Examples were evaluated by the following methods.

<Thickness of each resin layer>
After embedding the protective film in an epoxy resin, it was sliced using a microtome (RUB-2100, manufactured by Yamato Kogyo Co., Ltd.), and the cross section was observed and measured using a scanning electron microscope.

<Measurement of haze and total light transmittance>
Based on JIS K7361-1997, it measures using a turbidimeter (Nippon Denshoku Industries make, NDH-300A). In addition, about haze, the same measurement is performed 5 times and let the arithmetic mean value be a representative value of haze.

<Measurement of flexural modulus>
The bending elastic modulus of the a layer and the b layer of the base resin layer is measured using a tensile tester (Autograph AG-100kNIS, manufactured by Shimadzu Corp.) according to JIS K 7171.
<Scratch visibility test>
The surface hardness on the viewing side (antiglare layer) of the antiglare protective film is measured with a 500 g load using a 4H pencil in accordance with JIS K 5600-5-4. After the measurement polarizing plate is placed on the liquid crystal panel, the display is displayed in white, and the screen is observed at an angle of 45 degrees. If no scratches are observed with a pencil, the evaluation is ○, and if there are scratches, the evaluation is ×. The results are shown in Table 1.

(Production of polarizer)
A polyvinyl alcohol film having a refractive index of 1.545 at a wavelength of 380 nm and a refractive index of 1.521 at a wavelength of 780 nm and a thickness of 75 μm is uniaxially stretched 2.5 times to obtain 0.2 g of iodine and 60 g of potassium iodide. Was immersed in an aqueous solution containing 30 g / L for 30 seconds and then immersed in an aqueous solution containing 70 g / L of boric acid and 30 g / L of potassium iodide and simultaneously uniaxially stretched 6.0 times and held for 5 minutes. Finally, it was dried at room temperature for 24 hours to obtain a polarizer P having an average thickness of 30 μm and a polarization degree of 99.95%.

Production Example 1
(Preparation of protective film 1)
Polymethylmethacrylate resin (glass transition temperature Tg = 110 ° C .; hereinafter sometimes referred to as “PMMA1”) is introduced into a double flight type single screw extruder having a leaf disk-shaped polymer filter having an opening of 10 μm. At an outlet temperature of 260 ° C., the molten resin was supplied to one of the multi-manifold dies having a die slip surface roughness Ra of 0.1 μm.

On the other hand, an alicyclic olefin polymer (“Zeonor 1060R” manufactured by Nippon Zeon Co., Ltd .; water absorption of less than 0.01%, hereinafter sometimes referred to as “NB”) was provided with a leaf disk-shaped polymer filter having an aperture of 10 μm. The resin was introduced into a double flight type single screw extruder, and the molten resin was supplied to the other of the multi-manifold dies having a die slip surface roughness Ra of 0.1 μm at an extruder outlet temperature of 260 ° C.
Similarly, an ethylene-vinyl acetate copolymer (“EVAFLEX” manufactured by Mitsui DuPont Chemicals; hereinafter referred to as “EVA”) was also supplied to the other side of the multi-manifold die.

  Then, as a molten polymethyl methacrylate resin (PMMA1), an alicyclic olefin polymer (NB), and an adhesive, an ethylene-vinyl acetate copolymer (EVA) is discharged from the multi-manifold die at 260 ° C., respectively. It casts to the cooling roll temperature-controlled at 130 degreeC, Then, it passes through the cooling roll temperature-controlled at 50 degreeC, a layer (15 micrometers) which consists of PMMA1, adhesive layer (4 micrometers), b layer which consists of NB (32 micrometers) ) -Adhesive layer (4 [mu] m) -Protective film 1 having a width of 600 mm and a thickness of 80 [mu] m comprising a layer (15 [mu] m) composed of PMMA1 was obtained by coextrusion molding. The bending elastic modulus of the a layer of the protective film 1 was 3.3 GPa, and the bending elastic modulus of the b layer was 2.0 GPa.

(Preparation of anti-glare protective film 1 <addition of anti-glare layer>)
12 parts of polystyrene particles having an average particle size of 3.5 μm, 5 parts of benzophenone photopolymerization initiator, 2.5 parts of thixotropic agent (mica) per 100 parts of acrylic urethane UV curable resin (urethane acrylate monomer) Is applied to the upper surface of the protective film 1 and dried at 120 ° C. for 5 minutes, followed by curing by ultraviolet irradiation to obtain a coating film thickness. Produced the anti-glare protective film 1 having an anti-glare layer on the surface of the fine concavo-convex structure of 7 μm.

Production Example 2
(Preparation of protective film 2)
Instead of the polymethylmethacrylate resin (PMMA1) used in Production Example 1, polystyrene (“Toyostyrene GP.G320C” manufactured by Toyo Styrene Co., Ltd .; hereinafter sometimes referred to as “PS”) was used. In the same manner as in Production Example 1, a three-layer configuration of a layer (15 μm) made of PS, an adhesive layer (4 μm), a b layer (32 μm) made of NB, an adhesive layer (4 μm), and an a layer (15 μm) made of PS A protective film 2 having a width of 600 mm and a thickness of 80 μm was obtained. The bending elastic modulus of the a layer of the protective film 2 was 3.3 GPa, and the bending elastic modulus of the b layer was 2.0 GPa.
(Preparation of anti-glare protective film 2)
Except using this protective film 2, it carried out similarly to manufacture example 1, and obtained the glare-proof protective film 2 which has the glare-proof layer of the fine uneven | corrugated structure surface whose film thickness is 7 micrometers.

Production Example 3
(Preparation of protective film 3)
The polymethyl methacrylate resin (PMMA-1) used in Production Example 1 was extrusion molded to obtain a single layer (a layer) protective film 3 having a thickness of 80 μm. The bending elastic modulus of the a layer of the protective film 3 was 3.3 GPa.
(Preparation of anti-glare protective film 3)
Except using this protective film 3, it carried out similarly to manufacture example 1, and obtained the glare-proof protective film 3 which has the glare-proof layer of the fine uneven | corrugated structure surface whose film thickness is 7 micrometers.
Production Example 4
(Preparation of protective film 4)
The alicyclic olefin polymer (NB) used in Production Example 1 was extruded to obtain a single layer (a layer) protective film 4 having a thickness of 80 μm. The bending elastic modulus of the a layer of the protective film 4 was 2.1 GPa.
(Preparation of anti-glare protective film 4)
Except using this protective film 4, it carried out similarly to manufacture example 1, and obtained the glare-proof protective film 4 which has a glare-proof layer of the fine concavo-convex structure surface with a film thickness of 7 micrometers.

Example 1
One side of a 100 μm-thick unstretched film made of an alicyclic olefin polymer (glass transition temperature 136 ° C.) is subjected to corona discharge treatment using a high-frequency transmitter, and the surface tension is 0.
. Film 1B of 055 N / m was obtained. The haze of this film 1B was 0.1% or less, and the total light transmittance was 92%.

  An acrylic adhesive is applied to both surfaces of the polarizer P, one surface of the antiglare protective film 1 and the corona discharge treated surface of the film 1B are overlapped toward the polarizer P, and the polarizing plate 1 is bonded by a roll-to-roll method. Obtained.

Example 2
A polarizing plate 2 was obtained in the same manner as in Example 1 except that the antiglare protective film 2 was used instead of the antiglare protective film 1.

Comparative Example 1
A polarizing plate 3 was obtained in the same manner as in Example 1 except that the antiglare protective film 3 was used instead of the antiglare protective film 1.

Comparative Example 2
A polarizing plate 4 was obtained in the same manner as in Example 1 except that the antiglare protective film 4 was used instead of the antiglare protective film 1.

The following evaluation was performed about the obtained polarizing plates 1-4. The results are shown in Table 1.
<Flexibility test>
A polarizing plate was punched into 1 cm × 5 cm to obtain a test film. The obtained test film was wound around a steel rod having a diameter of 3 mmφ, and whether or not the wound film was broken at the rod was tested. The test was conducted a total of 10 times, and the flexibility was expressed by the following index according to the number of times the test was not broken.
○: No broken film pieces △: One broken film piece ×: Two or more broken film pieces

<Liquid crystal display performance evaluation test>
From the commercially available liquid crystal monitor (IPS mode 20V type liquid crystal monitor), the polarizing plate and viewing angle compensation film installed on the viewing side among the polarizing plate and viewing angle compensation film sandwiching the liquid crystal cell are peeled off, Polarizing plates 1 to 3 obtained in Examples and Comparative Examples were installed in the liquid crystal cell. Next, white characters are displayed with a black background, and the line of sight is moved up and down, left and right from the front, and the angle at which white characters cannot be read is measured.

<Evaluation of reflection>
A polarizing plate is installed in a room with a brightness of 1000 lux, the surface on which the antiglare layer is formed is placed on top, and reflection of reflected light is visually evaluated by the fluorescent lamp contour reflected on the surface.
○: The contour is not visible △: The contour is slightly visible ×: The contour is clearly visible

Claims (9)

A protective layer A containing a thermoplastic resin, comprising at least a layer and b layer, wherein the bending elastic modulus of the a layer is larger than that of the b layer, and the a layer is present on the viewer side;
A polarizer and a protective layer B
Laminated at least in this order from the viewer side,
A polarizing plate having a haze of 10 to 60%.   The polarizing plate according to claim 1, wherein a difference in flexural modulus between the a layer and the b layer is 0.2 GPa to 2.5 GPa.   The polarizing plate according to claim 1, wherein the protective layer A is obtained by a coextrusion method.   The polarizing plate for liquid crystal display of Claim 1 or 2 by which the glare-proof layer is laminated | stacked on the surface by the side of the visual recognition side of the protective layer A directly or through another layer.   The polarizing plate for liquid crystal displays according to claim 1 or 2, wherein an antiglare layer and an antireflection layer are laminated on the surface on the viewing side of the protective layer A directly or via another layer.   The protective layer A is a polarizing plate for liquid crystal display according to any one of claims 1 to 5, comprising an ultraviolet absorber.   The polarizing plate for liquid crystal displays according to any one of claims 1 to 6, wherein a surface on the viewing side of the protective layer A has an uneven shape.   The polarizing plate according to claim 1, wherein the polarizing plate has a layer including a region where the refractive index is discontinuous, directly or via another layer, on the surface on the viewing side of the protective layer A. A liquid crystal display device provided with the polarizing plate in any one of Claims 1-8.