JP2008040275A - Polarizing plate for liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate for liquid crystal display which does not cause visual defection due to light leakage, color irregularity due to interference fringes or the like, coloring or reflection of external light, has a large surface hardness, has flexibility, is excellent in scuffing resistance, is excellent in adhesiveness between a polarizer and a protective layer and can retain high polarization even under high temperature and high humidity conditions, and to provide a liquid crystal display device provided with the polarizing plate for liquid crystal display. <P>SOLUTION: Elastic particles of number average particle size 2.0 μm or less are dispersed into a thermoplastic resin to obtain a resin composition, and a thermoplastic resin and the resin composition are molded by co-extrusion to obtain a visual side protective layer which has a structure of thermoplastic resin layer/resin composition layer/thermoplastic resin layer, allows the elastic particles to unevenly be distributed on the center in the thickness direction of a film and has the average thickness less than 100 μm. The visual side protective layer and a liquid crystal cell side protective layer are stacked on both surfaces of a polarizer via an active energy ray curable solvent-free adhesive to obtain the polarizing plate for liquid crystal display. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarizing plate for liquid crystal display. More specifically, the present invention relates to a polarizing plate for liquid crystal display that protects the viewing-side surface of a liquid crystal display device, does not cause color unevenness due to interference fringes or the like, or poor visibility due to reflection of external light, has a high surface hardness, and has flexibility. .

The viewing side surface (display screen) of a display device or the like has many occasions where a human touches the surface, and the surface becomes dirty or the surface is scratched, and the display image may be difficult to see. Therefore, a protective layer is stuck on the display screen surface.
As a film used for protecting a display screen of a display device or the like, for example, Patent Document 1 discloses an acrylic made of 50 to 70 parts by mass of methyl methacrylate, 10 to 20 parts by mass of maleic anhydride, and 20 to 35 parts by mass of styrene. A composition containing a resin based resin (A) and a toughness improving agent (B) made of an impact-resistant acrylic rubber-methyl methacrylate graft copolymer, butyl-modified acetylcellulose, or the like at a mass ratio of 60 to 90 / 40-10 A polarizing film protective film made of a material has been proposed.

Patent Document 2 discloses an acrylic resin film containing 60 to 90% by mass of an acrylic resin (A) containing a glutaric anhydride unit and 7 to 40% by mass of acrylic elastic particles (B). An acrylic resin film in which the average particle diameter of the body particles (B) is 70 to 300 nm, the breaking elongation of the film is 15% or more, and the 1% deformation temperature under high tension is 100 ° C. or more has been proposed. However, these protective layers have a problem in that the surface hardness is small and the surface is scratched or soiled by rubbing the surface.
Japanese Patent Laid-Open No. 5-119217 JP 2005-314534 A

On the other hand, in Patent Document 3, a rubber-like elastic body is dispersed in the form of particles having a particle diameter of 0.15 to 4 μm in a continuous resin phase mainly composed of methyl methacrylate and dispersed in an amount of 5 to 70% by mass. 0.5 μm on one surface or both surfaces of the base material portion, with the impact-resistant acrylic resin used as the base material portion and the general acrylic resin having an alkyl methacrylate unit having an alkyl group having 1 to 4 carbon atoms as the laminated portion. The haze value is 1.0% or less and the glossiness is 130% or more when the thickness is 100 μm to 100 μm and the total thickness of the laminated part is within 30% of the total thickness of the sheet. An impact-resistant acrylic resin laminate sheet having optical properties and excellent weather resistance has been proposed. Patent Document 3 discloses that this film is used for applications that require impact resistance, such as signs, lighting covers, and automobile sun visors.
JP-A-4-59246

Patent Documents 4 and 5 propose an acrylic resin laminated film including a layer containing acrylic rubber particles and an acrylic resin, and an acrylic resin layer not containing an impact-resistant material. It is disclosed that this film is used for exteriors of household electrical appliances, automobile interiors, building materials, etc. that require high impact strength.
JP 2002-292808 A JP 2001-260288 A

Patent Document 6 includes an acrylic resin layer that includes an acrylic resin layer in which rubber particles are dispersed in methacrylic resin as a film for protecting a display screen of a portable information terminal, and has a thickness of 100 μm or more and 1,800 μm or less. A scratch-resistant acrylic resin film in which a scratch-resistant film obtained by curing a curable paint is formed on the surface of a resin film has been proposed. Although this protective layer is suitable for the viewing side of a narrow area such as a portable information terminal, the surface hardness is insufficient as a protective layer for a display device having a wide display screen.
JP 2004-143365 A

  An object of the present invention is to prevent light leakage, color unevenness due to interference fringes, coloring, and poor visual recognition due to reflection of external light, a hard surface hardness, flexibility, and excellent scratch resistance, and a polarizer. Another object of the present invention is to provide a polarizing plate for liquid crystal display and a liquid crystal display device that are excellent in adhesion between the protective layer and the protective layer and can maintain a high degree of polarization even under high temperature and high humidity conditions.

  As a result of investigations to achieve the above object, the inventors of the present invention include a thermoplastic resin as a main component, and an elastic particle having a number average particle size of 2.0 μm or less is in the center in the thickness direction of the viewing side protective layer. A polarizing plate in which a viewing-side protective layer that is unevenly distributed in an area and has an average thickness of less than 100 μm and a polarizer are laminated via an active energy ray-curable adhesive that does not contain a solvent. Due to light leakage, color unevenness due to interference fringes, coloring, and poor visibility due to reflection of external light do not occur, the surface hardness is hard, the film has flexibility, scratch resistance, and a polarizer and a protective layer. It has been found that a liquid crystal display device which is excellent in the adhesiveness and can maintain a high degree of polarization even under high temperature and high humidity conditions can be obtained. The present invention has been completed as a result of further studies based on this finding.

That is, the present invention includes the following.
(1) A viewing side comprising a thermoplastic resin, wherein elastic particles having a number average particle diameter of 2.0 μm or less are unevenly distributed in the central portion in the thickness direction of the viewing side protective layer, and the average thickness is less than 100 μm A protective layer;
With a polarizer,
It is laminated through an active energy ray-curable adhesive that does not contain a solvent.
A polarizing plate for liquid crystal display.
(2) The average thickness having a layer composed of a thermoplastic resin and elastic particles having a number average particle diameter of 2.0 μm or less and a layer composed of a thermoplastic resin laminated on both sides of the layer is less than 100 μm A viewer-side protective layer;
With a polarizer,
It is laminated through an active energy ray-curable adhesive that does not contain a solvent.
A polarizing plate for liquid crystal display.
(3) The polarizing plate for liquid crystal display as described in (1) or (2) in which a visual recognition side protective layer contains a ultraviolet absorber.
(4) The polarizing layer for liquid crystal display according to any one of (1) to (3), wherein the viewing-side protective layer has a moisture permeability of 10 g · m ⁻² day ⁻¹ or more and 200 g · m ⁻² day ⁻¹ or less. Board.
(5) A liquid crystal display device comprising the polarizing plate according to any one of (1) to (4).

  The polarizing plate of the present invention is flexible and excellent in flexibility, and does not cause visual defects such as interference fringes on the display screen, and further has no visual defects due to light leakage, color unevenness, coloring, etc. near the frame of the display screen. Equipment can be provided. Furthermore, since the surface hardness is high, it has excellent scratch resistance. Furthermore, the polarizing plate of the present invention has little reflection of external light, excellent adhesion between the polarizer and the protective layer, and can maintain a high degree of polarization even under high temperature and high humidity conditions.

    The polarizing plate of the present invention is formed by laminating a viewing-side protective layer and a polarizer via an active energy ray-curable adhesive that does not contain a solvent. Moreover, the liquid crystal cell side protective layer may be laminated | stacked on the opposite side to the side by which the visual recognition side protective layer was laminated | stacked on the polarizer. In order to laminate the viewing-side protective layer on the polarizer, an active energy ray-curable adhesive that does not contain a solvent is used.

(Active energy ray-curable adhesive without solvent)
In the present invention, the adhesive used for laminating the viewing-side protective layer and the polarizer is an adhesive that cures when irradiated with active energy rays and does not contain a solvent (solvent-free).
Here, “does not contain solvent” means that the adhesive used for applying to the adherend does not contain any solvent, or the solvent content is less than 2% by weight based on the total weight of the adhesive. Say. The solvent content in the adhesive can be measured by gas chromatography or the like.

  Solvents include aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, propanol, isopropanol and n-butanol; acetone and butanone , Ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as methyl acetate, ethyl acetate and butyl acetate; cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; halogenation such as methylene chloride and chloroform And hydrocarbons.

Moreover, the active energy ray-curable solvent-free adhesive used in the present invention is excellent in adhesive applicability when the viscosity measured by a B-type viscometer at 23 ° C. is 200 to 5000 mPa · s.
As the solvent-free adhesive that is cured by active energy rays, a known one can be used without particular limitation as long as it is colorless and transparent. Examples of the active energy ray-curable compound that is the main component of the active energy ray-curable solvent-free adhesive include radical polymerization by active energy rays such as compounds having acryloyl group, methacryloyl group, allyl group, etc. as functional groups. Cured (photo radical polymerizable compound); cured by a photocation reaction by an active energy ray of a compound having a functional group such as epoxy group, oxetane group, hydroxyl group, vinyl ether group, episulfide group, ethyleneimine group, etc. (Photo cationic polymerizable compound);

  As photoradical polymerizable compounds, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; hydroxyaryl acrylates such as 2-hydroxy-3-phenoxypropyl acrylate; 2-acryloyloxyethyl succinic acid, 2- Acrylic modified carboxylic acids such as acryloyloxyethylphthalic acid; polyethylene glycol diacrylates such as triethylene glycol diacrylate and tetraethylene glycol diacrylate; polypropylene glycol diacrylates such as dipropylene glycol diacrylate and tripropylene glycol diacrylate Other, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,9-no Diol diacrylate, bisphenol A ethylene oxide modified diacrylate, bisphenol A propylene oxide modified diacrylate, dimethylol tricyclodecane diacrylate, trimethylol propane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate Such as epoxy acrylate, urethane acrylate, other acrylates such as acrylic benzoic acid mixed ester of neopentyl glycol; methacrylates thereof, and the like.

  Bisphenol type epoxy resin such as bisphenol A type epoxy resin and bisphenol F type epoxy resin; novolak type epoxy resin such as phenol novolac type epoxy resin and cresol novolac type epoxy resin; aliphatic epoxy resin, alicyclic Type epoxy resin, heterocyclic epoxy resin, polyfunctional epoxy resin, biphenyl type epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin; alcohol such as hydrogenated bisphenol A type epoxy resin Type epoxy resin; halogenated epoxy resin such as brominated epoxy resin; rubber-modified epoxy resin, urethane-modified epoxy resin, epoxidized polybutadiene, epoxidized styrene-butadiene-styrene Compounds having an epoxy group, such as a polyblock copolymer, an epoxy group-containing polyester resin, an epoxy group-containing polyurethane resin, and an epoxy group-containing acrylic resin; phenoxymethyl oxetane, 3,3-bis (methoxymethyl) oxetane, 3,3- Bis (phenoxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3-{[3- (triethoxysilyl) Propoxy] methyl} oxetane, di [1-ethyl (3-oxetanyl)] methyl ether, oxetanylsilsesquioxane, phenol novolac oxetane, 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} Compounds having an oxetanyl group such as benzene It is below.

  These active energy ray-curable compounds may be used alone or in combination.

  A polymerization initiator can be mix | blended with an active energy ray hardening-type adhesive in order to raise the curing reaction efficiency of the above-mentioned active energy ray hardening-type adhesive agent. The polymerization initiator is selected according to the type of active energy ray used. As the polymerization initiator, photo radical polymerization initiators such as acetophenone, benzophenone, thioxanthone, benzoin, and benzoin alkyl ethers; aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts, metathelone compounds, benzoin sulfones Photocationic polymerization initiators such as acid esters; and the like. These can be used individually by 1 type or in combination of 2 or more types.

  As the acetophenone photopolymerization initiator, for example, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1- [ 4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone and the like.

Examples of the benzoin alkyl ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.
Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like.

  The cationic photopolymerization initiator may be an ionic photoacid-generating photocationic polymerization initiator or a nonionic photoacid-generating photocationic polymerization initiator. The photocationic polymerization initiator is a photocationic polymerization initiator that is activated by light having a wavelength of 350 nm or more because it can effectively initiate and advance the photocationic polymerization of the photocationically polymerizable compound. Is preferred.

  The ionic photoacid-generating photocationic polymerization initiator is not particularly limited. For example, onium salts such as aromatic diazonium salt, aromatic halonium salt, aromatic sulfonium salt; organometallic complexes such as iron-allene complex, titanocene complex, arylsilanol-aluminum complex; tetrakis (pentafluorophenyl) borate, etc. Examples thereof include a photocationic polymerization initiator having a bulky counter anion. These ionic photoacid-generating photocationic polymerization initiators may be used alone or in combination of two or more.

  Examples of commercially available ionic photoacid-generating photocationic polymerization initiators include “Adekaoptomer” series such as “Adekaoptomer SP150” and “Adekaoptomer SP170” manufactured by Asahi Denka Kogyo Co., Ltd. , A trade name “UVE-1014” manufactured by General Electronics Co., Ltd., a product name “CD-1012” manufactured by Sartomer, and a product name “Photoinitiator 2074” manufactured by Rhodia.

  The nonionic photoacid-generating photocationic polymerization initiator is not particularly limited. For example, nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenolsulfonic acid ester, diazonaphthoquinone, N-hydroxyimidophosphonate and the like can be mentioned. These nonionic photoacid-generating photocationic polymerization initiators may be used alone or in combination of two or more.

  The compounding quantity of a polymerization initiator is 0.5-10 weight part normally with respect to 100 weight part of active energy ray hardening compounds.

  In addition, the active energy ray curable adhesive contains a photosensitizer, antistatic agent, infrared absorber, ultraviolet absorber, antioxidant, organic particles, inorganic oxide particles, metal powder, pigment, dye, etc. May be.

  By using a photosensitizer, the reactivity is improved, and the mechanical strength and adhesive strength of the cured adhesive can be improved. The photosensitizer is not particularly limited, and examples thereof include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreducible dyes.

  Specific examples of the photosensitizer include benzoin methyl ether, benzoin isopropyl ether, benzoin derivatives such as α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, Benzophenone derivatives such as 4,4′-bis (dimethylamino) benzophenone and 4,4′-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2-chloroanthraquinone, 2- Anthraquinone derivatives such as methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; other, α, α-diethoxyacetophenone, benzyl, fluorenone, xanthone, Examples include uranyl compounds and halogen compounds, but are not limited thereto. These may be used alone or in combination. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight when the active energy ray-curable compound is 100 parts by weight.

  In the polarizing plate of the present invention, the visible-side protective layer is bonded to one surface of the polarizer via the active energy ray-curable adhesive and then irradiated with active energy rays to cure the visible-side protective layer. It is obtained by fixing the layer to a polarizer.

  There is no particular limitation on the method of applying the adhesive to the polarizer, and various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used.

  Prior to bonding the viewing-side protective layer to the polarizer, the bonding surface may be subjected to easy adhesion processing such as saponification processing, corona processing, primer processing, and anchor coating processing.

  In the present invention, light is usually used as the active energy ray. Although the said light is not specifically limited, For example, a microwave, infrared rays, visible light, an ultraviolet-ray, X-ray | X_line, a gamma ray etc. are mentioned. In particular, ultraviolet rays are preferably used because of easy handling and relatively high energy.

The light source used for irradiating with ultraviolet rays is not particularly limited, and examples thereof include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, and a metal halide lamp. The irradiation intensity is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is preferably 0.1 to 100 mW / cm ² . When the light irradiation intensity is less than 0.1 mW / cm ² , the reaction time becomes too long, and when it exceeds 100 mW / cm ² , the adhesive is yellowed or polarized due to radiation heat from the lamp, polymerization reaction heat, or the like. The child itself may be deteriorated. The light irradiation time is appropriately selected according to the curing state and is not particularly limited. However, the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 5,000 mJ / cm ^2. It is preferable to set to.

(Polarizer)
The polarizer used in the present invention is obtained by adsorbing iodine or dichroic dye on a polyvinyl alcohol film and then uniaxially stretching in a boric acid bath, or iodine or dichroic dye on a polyvinyl alcohol film. And the like obtained by adsorbing and stretching, and further modifying a part of the polyvinyl alcohol unit in the molecular chain into a polyvinylene unit. In addition, a polarizer having a function of separating polarized light into reflected light and transmitted light, such as a grid polarizer, a multilayer polarizer, and a cholesteric liquid crystal polarizer, can also be used as the polarizer. Among these, a polarizer comprising polyvinyl alcohol is preferable. The polarization degree of the polarizer is preferably 98% or more, more preferably 99% or more. The thickness (average thickness) of the polarizer is preferably 5 μm to 80 μm.

(Viewing side protective layer)
The viewing-side protective layer used in the present invention comprises a thermoplastic resin, elastic particles having a number average particle size of 2.0 μm or less are unevenly distributed in the central portion in the thickness direction of the viewing-side protective layer, and have an average thickness. Is less than 100 μm.

  The thermoplastic resin used for the viewing side protective layer is not particularly limited as long as it is a transparent resin. For example, polycarbonate resin, polyether sulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate Examples thereof include resins, polyethylene resins, polyvinyl chloride resins, diacetyl cellulose, triacetyl cellulose, and alicyclic olefin polymers. Of these, a thermoplastic acrylic resin is preferred.

As thermoplastic acrylic resins, homopolymers of (meth) acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate; the hydrogen of the alkyl group is an OH group, a COOH group, or an NH ₂ group Homopolymer of (meth) acrylic acid alkyl ester substituted with a functional group such as: or (meth) acrylic acid alkyl ester and styrene, vinyl acetate, α, β-monoethylenically unsaturated carboxylic acid, vinyl toluene, Examples thereof include a copolymer with a vinyl monomer having an unsaturated bond such as α-methylstyrene. As a thermoplastic acrylic resin, only 1 type may be used among these and it may use it in combination of 2 or more type. More preferably, the thermoplastic acrylic resin contains polymethyl methacrylate and polybutyl methacrylate as monomer units.

  The thermoplastic resin used in the present invention preferably has a glass transition temperature Tg in the range of 80 to 120 ° C. Furthermore, the thermoplastic resin used in the present invention has a high surface hardness when formed into a film, specifically, pencil hardness (according to JIS K5600-5-4 except that the test load is 500 g). More than 2H is preferable.

  Thermoplastic resins include colorants such as pigments and dyes, optical brighteners, dispersants, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, solvents, etc. These can be used in which compounding agents other than the elastic particles described later are appropriately blended. In addition, it is preferable that these compounding agents are unevenly distributed in the thickness direction center part of a visual recognition side protective layer like the elastic body particle mentioned later. For example, a layer made of a thermoplastic resin containing an infrared absorber and / or an ultraviolet absorber and a layer made of a thermoplastic resin not containing an infrared absorber and / or an ultraviolet absorber sandwiching this layer are laminated. The viewing side protective layer which becomes is mentioned as a suitable aspect.

The ultraviolet absorber is added to improve durability by absorbing ultraviolet rays of 400 nm or less.
As the ultraviolet absorber, known ones such as a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and an acrylonitrile ultraviolet absorber can be used. Among them, 2,2'-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3 '-Tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2,2'-dihydroxy- 4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone and the like are preferably used. Among these, 2,2′-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) is particularly preferable. The concentration of the ultraviolet absorber can be selected within a range where the transmittance at a wavelength of 370 nm or less is preferably 10% or less, more preferably 5% or less, and still more preferably 2% or less. Examples of the method of containing the ultraviolet absorber include a method of previously blending the ultraviolet absorber into the thermoplastic resin; a method of directly supplying the melt during the melt extrusion molding, and any method may be employed.

  It is preferable that the ultraviolet absorber is unevenly distributed in the central portion in the thickness direction of the viewing side protective layer. When the viewing-side protective layer is composed of a laminate, the UV absorber concentration contained in the thermoplastic resin layer containing elastic particles is the UV absorption contained in the thermoplastic resin layer not containing elastic particles. The concentration should be higher than the agent concentration. Specifically, the concentration of the ultraviolet absorber in the thermoplastic resin layer not containing elastic particles is preferably 0 to 1.0% by weight, more preferably 0 to 0.5% by weight. The concentration of the ultraviolet absorber in the thermoplastic resin layer containing particles is preferably 0.5 to 10% by weight, more preferably 1.0 to 5.0% by weight. When the content of the ultraviolet absorber is within the above range, it is possible to efficiently block ultraviolet rays without deteriorating the color tone of the polarizing plate, and to prevent a decrease in the degree of polarization during long-term use. If the content of the ultraviolet absorber in the thermoplastic resin layer containing the elastic particles is too small, the light transmittance at a wavelength of 370 nm or less increases, and the degree of polarization tends to decrease. On the other hand, when the content of the ultraviolet absorber is too large, the light transmittance on the short wavelength side becomes small, and the laminate tends to be yellowish.

  Infrared absorbers include nitroso compounds, metal complexes thereof, cyanine compounds, squarylium compounds, thiol nickel complex compounds, phthalocyanine compounds, naphthalocyanine compounds, triallylmethane compounds, imonium compounds, diimonium compounds, Infrared absorption of naphthoquinone compounds, anthraquinone compounds, amino compounds, aminium salt compounds, carbon black, indium tin oxide, antimony tin oxide, oxides of metals belonging to Group 4A, 5A or 6A, carbides, borides, etc. An agent etc. can be mentioned. These infrared absorbers are preferably selected so as to be able to absorb the entire infrared ray (light having a wavelength in the range of about 800 nm to 1100 nm), and two or more types may be used in combination. The amount of the infrared absorber can be appropriately adjusted so that, for example, the light transmittance at a wavelength of 800 nm or more is 10% or less.

<Elastic particles>
The elastic particles used in the present invention are particles made of a rubber-like elastic body. 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, and typical examples thereof include an alkyl acrylate such as butyl acrylate, a grafted rubber elastic component of styrene, and polymethyl. Examples thereof include elastic particles in which a hard resin layer made of a copolymer of methacrylate and / or methyl methacrylate and an alkyl acrylate forms a core-shell structure.

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

In the present invention, the refractive index n _a (lambda) is the wavelength 380nm~780nm of elastic particles, between the refractive index n _b (λ) at a wavelength 380nm~780nm thermoplastic resin as a matrix, | n _a ( It is preferable that the relationship of λ) −n _b (λ) | ≦ 0.05 is satisfied. In particular, it is more preferable that | n _a (λ) −n _b (λ) | ≦ 0.045. Incidentally, n _a (lambda) and n _b (lambda) is the average value of the principal refractive index at a wavelength lambda. When the value of | n _a (λ) −n _b (λ) | exceeds the above value, transparency may be impaired due to interface reflection caused by a difference in refractive index at the interface.

  The elastic particles are unevenly distributed in the central portion in the thickness direction of the viewing-side protective layer mainly composed of a thermoplastic resin. That is, there are few elastic particles in the vicinity of the surface of the viewing side protective layer, and many elastic particles are distributed in the central portion in the thickness direction of the viewing side protective layer. The distribution of the elastic particles in the thickness direction of the viewer-side protective layer may increase gradually from the surface toward the center or may increase stepwise.

  As an aspect that increases stepwise, a layer composed of a thermoplastic resin and elastic particles having a number average particle diameter of 2.0 μm or less and a layer composed of a thermoplastic resin are laminated on both sides of the layer. A viewing-side protective layer having an average thickness of less than 100 μm can be mentioned. There is no particular limitation on the method for obtaining the visible-side protective layer. For example, a base film is obtained by molding a composition comprising a thermoplastic resin and elastic particles having a number average particle size of 2.0 μm or less. The method of apply | coating the thermoplastic resin which does not contain an elastic body particle | grain on both surfaces of a material film is mentioned. As another method, there is a method in which a film formed by molding a thermoplastic resin not containing elastic particles is bonded to both surfaces of the base film with an adhesive if necessary. Another method includes a method of co-extrusion of a composition comprising a thermoplastic resin and elastic particles having a number average particle size of 2.0 μm or less and a thermoplastic resin not containing elastic particles. . In addition, a method in which a film in which elastic particles having a number average particle size of 2.0 μm or less are unevenly distributed on one side is bonded so that the surfaces in which the elastic particles are unevenly contacted is also mentioned.

  As described above, the elastic particles are unevenly distributed in the central portion in the thickness direction of the layer, whereby the central portion in the thickness direction of the viewing-side protective layer becomes a flexible layer, and both surfaces of the viewing-side protective layer become hard layers. By setting it as such a structure, the flexibility of a polarizing plate can be improved, ensuring sufficient hardness of the surface of the visual recognition side protective layer.

  In obtaining a visible-side protective layer in which a layer made of thermoplastic resin and elastic particles and a layer made of thermoplastic resin not containing elastic particles are laminated on both sides of the layer, an adhesive (including an adhesive) is obtained. ), The average thickness of the adhesive layer made of an adhesive is usually 0.01 μm to 30 μm, preferably 0.1 μm to 15 μm. The adhesive layer is a layer having a tensile fracture strength according to JIS K7113 of 40 MPa or less. The adhesive constituting this adhesive layer includes acrylic adhesive, urethane adhesive, polyester adhesive, polyvinyl alcohol adhesive, polyolefin adhesive, modified polyolefin adhesive, polyvinyl alkyl ether adhesive, rubber adhesive, vinyl chloride, Vinyl acetate adhesive, styrene / butadiene / styrene copolymer (SBS copolymer) adhesive, hydrogenated product (SEBS copolymer) adhesive, ethylene / vinyl acetate copolymer, ethylene-styrene copolymer, etc. Ethylene adhesives and acrylic ester adhesives such as ethylene / methyl methacrylate copolymers, ethylene / methyl acrylate copolymers, ethylene / ethyl methacrylate copolymers, and ethylene / ethyl acrylate copolymers And so on.

The viewing-side protective layer has a thickness (average thickness) of less than 100 μm, preferably 80 μm or less, more preferably 40 μm or more and 80 μm or less.
The difference between the thickness of the thermoplastic resin layer that does not include one elastic particle and the thickness of the thermoplastic resin layer that does not include the other elastic particle on both sides of the viewing-side protective layer is 20 μm or less. Preferably, it is 10 μm or less, more preferably closer to 0 μm.

The viewing-side protective layer preferably has a residual solvent content of 0.01% by mass or less. When the residual solvent amount is in the above range, for example, it is possible to prevent the protective layer from being deformed in a high temperature / high humidity environment and to prevent the optical performance from deteriorating. The viewing-side protective layer in which the residual solvent amount falls within the above range can be obtained, for example, by co-extrusion molding a plurality of resins or by laminating a single thermoplastic resin layer by dry lamination or thermal lamination. . What was obtained by coextrusion molding from the point of productivity is preferable. In the case of coextrusion molding, it is not necessary to go through a complicated process (for example, a drying process or a coating process). Therefore, there is little mixing of external foreign matters such as dust, and excellent optical performance can be exhibited.
The residual solvent content was determined by placing 50 mg of the protective layer in a 4 mm inner diameter glass tube sample container from which moisture and organic matter adsorbed on the surface had been completely removed, heating the container at a temperature of 200 ° C. for 30 minutes, and removing it from the container. It is the value which collected the collected gas continuously and analyzed the collected gas with the thermal desorption gas chromatography mass spectrometer (TDS-GC-MS).

The viewing-side protective layer preferably has a moisture permeability of 10 g · m ⁻² day ⁻¹ or more and 200 g · m ⁻² day ⁻¹ or less. By setting the moisture permeability of the viewing-side protective layer within the above-described preferable range, the adhesion between the layers constituting the viewing-side protective layer can be improved. The moisture permeability can be measured by the cup method described in JIS Z 0208 under the test conditions for 24 hours in an environment of 40 ° C. and 92% RH.

  Furthermore, the polarizing plate of the present invention may have a functional layer such as a hard coat layer, an antireflection layer, and an antifouling layer on the viewing side.

(Hard coat layer)
The hard coat layer is a layer having a function of increasing the surface hardness of the viewer-side protective layer, and exhibits a hardness of “H” or higher in a pencil hardness test (a test plate is a glass plate) shown in JIS K5600-5-4. It is preferable. The viewing-side protective layer provided with such a hard coat layer preferably has a pencil hardness of 4H or higher. The material for forming the hard coat layer (hard coat material) is preferably a material that is cured by heat or light. For example, organic hard such as organic silicone, melamine, epoxy, acrylic, urethane acrylate, etc. Coating materials; inorganic hard coat materials such as silicon dioxide; and the like. Among these, urethane acrylate-based and polyfunctional acrylate-based hard coat materials are preferable from the viewpoint of good adhesive strength and excellent productivity.

  The hard coat layer contains various fillers for the purpose of adjusting the refractive index, improving the flexural modulus, stabilizing the volume shrinkage, and improving heat resistance, antistatic properties, and antiglare properties, as desired. it can. Further, the hard coat layer can contain additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, and an antifoaming agent.

(Antireflection layer)
The antireflection layer is a layer for preventing the transfer of external light, and is laminated directly or via another layer such as a hard coat layer on the surface (surface exposed to the outside) of the viewing side protective layer. The viewing-side protective layer provided with the antireflection layer preferably has a reflectance of 2.0% or less at an incident angle of 5 ° and a wavelength of 430 nm to 700 nm, and a reflectance of 1.0% or less at a wavelength of 550 nm. It is preferable.

  The thickness of the antireflection layer is preferably 0.01 μm to 1 μm, more preferably 0.02 μm to 0.5 μm. The antireflection layer has a refractive index smaller than the refractive index of a layer (such as a protective layer or a hard coat layer) on which the antireflection layer is laminated, specifically a low refractive index of 1.30 to 1.45. Examples thereof include those composed of a refractive index layer; those obtained by alternately laminating a plurality of low refractive index layers of a thin film made of an inorganic compound and high refractive index layers of a thin film made of an inorganic compound.

  The material for forming the low refractive index layer is not particularly limited as long as it has a low refractive index. Examples thereof include a resin material such as an ultraviolet curable acrylic resin, a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in the resin, and a sol-gel material using a metal alkoxide such as tetraethoxysilane. The material for forming these low refractive index layers may be a polymerized polymer, or may be 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 antifouling property.

As the sol-gel material, a sol-gel material containing a fluorine group is preferably used. Examples of the sol-gel material containing a fluorine group include perfluoroalkylalkoxysilane. Perfluoroalkylalkoxysilane is, for example, CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃ (wherein R represents an alkyl group having 1 to 5 carbon atoms, and n is 0 to 12). A compound represented by an integer). Specifically, as perfluoroalkylalkoxysilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane , And heptadecafluorodecyltriethoxysilane. Among these, the compound whose said n is 2-6 is preferable.

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

(Anti-fouling layer)
The antifouling layer is a layer that can impart water repellency, oil repellency, sweat resistance, antifouling properties, and the like. 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, and polymer compounds 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 nm to 50 nm, more preferably 3 nm to 35 nm.
Further, the viewing-side protective layer may be provided with other layers such as an antiglare layer, a gas barrier layer, a transparent antistatic layer, a primer layer, an electromagnetic shielding layer, and an undercoat layer.

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 visual side protective layer of the present invention is subjected to mechanical treatment by etching, sandblasting, embossing roll, etc. for the purpose of enhancing adhesion with the functional layer and imparting antiglare property. May be.
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.

(Liquid crystal cell side protective layer)
The liquid crystal cell side protective layer used in the present invention may be the same as the above-described viewing side protective layer, or may be a liquid crystal cell side protective layer conventionally used for polarizing plates.

  As the resin constituting the conventional protective layer on the liquid crystal cell side, polycarbonate resin, polyethersulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polystyrene resin, polychlorinated resin A vinyl resin, a cellulose ester, an alicyclic olefin polymer, etc. can be mentioned. 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. .

  There is no particular limitation on the method of laminating the liquid crystal cell side protective layer on the polarizer, for example, a general method of laminating a protective film to be the liquid crystal cell side protective layer with the polarizer through an adhesive as necessary. Can be adopted. As an adhesive for bonding the liquid crystal cell-side protective layer to the polarizer, the above-mentioned active energy ray-curable adhesive may be used, or a conventionally known adhesive may be used.

  The liquid crystal cell-side protective layer 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 even more preferably 90% or more.

The polarizing plate of the present invention may be obtained by laminating a film showing birefringence on the liquid crystal cell side protective layer side in addition to the above-mentioned viewing side protective layer, polarizer and liquid crystal cell side protective layer. In this case, the liquid crystal cell side 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.
The in-plane direction retardation Re, retardation Rth in the thickness direction, the thickness of the film upon the d (nm), Re = ( n x -n y) × d, Rth = ((n _x + _ny ) / 2- _nz ) × d. _nx and _ny are in-plane main refractive indexes ( _nx ≧ _ny ); _nz is a refractive index in the thickness direction; and d is an average thickness.

  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.

Moreover, you may use the film which shows the above birefringence as a liquid crystal cell side protective layer.
When a birefringent film is used as the liquid crystal cell side protective layer, or when a birefringent film is laminated on the liquid crystal cell side protective layer, optical compensation functions such as color compensation and viewing angle compensation are provided. The visibility of the liquid crystal display device is improved.

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

<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.

An Example and a comparative example are shown and this invention is demonstrated in detail. Parts and% are based on mass unless otherwise specified.
The protective films obtained in Examples and Comparative Examples were evaluated by the following methods.

<Bending elastic modulus>
Using a thermoplastic resin used to form each layer, a test piece is formed so as to meet the provisions of JIS K 7171. According to JIS K 7171, a tensile tester (“Autograph AG-100kNIS” manufactured by Shimadzu Corporation) is used. ).

<Thickness of each resin layer>
The protective film was embedded in an epoxy resin, 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.

(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%.

(Preparation of protective film)
A polymethylmethacrylate resin not containing elastic particles (tensile elastic modulus 3.3 GPa, flexural modulus 3.3 GPa; hereinafter referred to as “PMMA”) is applied to a leaf disk-shaped polymer filter having an aperture of 10 μm. It is put into a hopper mounted on the installed double flight type single screw extruder (ratio of screw effective length L and screw diameter D L / D = 28), the extruder outlet temperature is 260 ° C., and the speed of the gear pump of the extruder At 6 rpm, the molten resin was supplied to one of the multi-manifold dies having a die slip surface roughness Ra of 0.1 μm.

At the same time, a polymethyl methacrylate resin (tensile elastic modulus 2.8 GPa, flexural modulus 2.1 GPa; hereinafter referred to as “R ¹ -PMMA”) containing elastic particles having a number average particle diameter of 0.4 μm. And a multi-manifold having a die-slip surface roughness Ra of 0.1 μm introduced into a double-flight type single-screw extruder equipped with a leaf disk-shaped polymer filter having an opening of 10 μm and an extruder outlet temperature of 260 ° C. Feeded to the other side of the die.

The molten PMMA and R ¹ -PMMA are each discharged from the multi-manifold die at 260 ° C., cast into a cooling roll adjusted to 130 ° C., and then passed through a cooling roll adjusted to 50 ° C. Thus, a protective film having a width of 600 mm and a thickness of 80 μm composed of a three-layer structure of PMMA layer (20 μm) / R ¹ -PMMA layer (40 μm) / PMMA layer (20 μm) was obtained by coextrusion molding. The haze of the protective film was 1% or less.

(Preparation of active energy ray-curable adhesive 1)
Terminal energy-modified polybutadiene (Nippon Soda Co., Ltd., "R-45ACR") 35 parts by weight, isobornyl acrylate 60 parts by weight, and 1-hydroxy-cyclophenyl-phenyl ketone 3 parts by weight are mixed to form an active energy ray curable type. Adhesive 1 was obtained.

(Preparation of active energy ray-curable adhesive 2)
95 parts by weight of 3-ethyl-3 [(phenoxy) methyl] oxetane (“PhOX” manufactured by Toagosei Co., Ltd.), 3 parts by weight of a polybutadiene-based epoxy compound, 3 parts by weight of an alicyclic epoxy compound (“ERL4206” manufactured by Union Carbide) And 3 parts by weight of an antimony sulfonium salt compound (“SP-170” manufactured by Asahi Denka Kogyo Co., Ltd.) were mixed to obtain an active energy ray-curable adhesive 2.

Example 1
A protective film was bonded to both surfaces of the polarizer P via an active energy ray-curable adhesive 1, and ultraviolet rays with an integrated light amount of 3000 mJ / cm ² were irradiated to obtain a polarizing plate 1.

Example 2
A polarizing plate 2 was obtained in the same manner as in Example 1 except that the active energy ray curable adhesive 1 was used instead of the active energy ray curable adhesive 1.

Comparative Example 1
A 10% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., “PVA203”) was dropped onto both surfaces of the polarizer P, a protective film was bonded thereto, and heated at 130 ° C. for 10 minutes to obtain a polarizing plate 3.

<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 3 mmφ steel rod, and it was tested whether the wound film was broken at the rod. 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

(Adhesion)
Adhesiveness was determined by the cross-cut method described in JIS-K5600-5-6. Specifically, 100 square cuts were made using a cutter guide with a gap interval of 2 mm. Next, an adhesive tape (manufactured by Nichiban Co., Ltd., trade name: CT24) was attached to the grid-shaped cut surface and rubbed with an eraser to be completely attached. The adhesive tape was then peeled off vertically. The tape peeling surface was visually observed and evaluated according to the following criteria.
○: The cut edge is smooth and there is no peeling.
X: Peeling is seen.

(Change in polarization degree)
Two polarizing plates cut out in a size of 10 inches square are prepared, and the transmittance (H ₀ ) at the diagonal line intersection of the overlapping polarizing plates so that the polarization axes are parallel to each other is a two-degree field of view (C light source) of JIS Z8701. ) Using a spectrophotometer. Next, the transmittance (H ₉₀ ) at the diagonal intersection of the stacked polarizing plates was measured in the same manner so that the polarization axes were orthogonal. The polarization degree was calculated from the measured value based on the following formula.
Polarization degree (%) = [(H ₀ -H ₉₀ ) / (H ₀ + H ₉₀ )] ^1/2 × 100
(H ₀ and H ₉₀ are Y values with corrected visibility.)
Next, the two polarizing plates are attached as follows. ~ 5. Then, the degree of polarization at the diagonal intersection of the polarizing plate was obtained in the same manner, and the change in the degree of polarization before and after being left under high temperature and high humidity was obtained in the same manner.
1. High temperature environment: 80 ° C., humidity 50%, 500 hours 2. High temperature and high humidity environment 1: Temperature 60 ° C, humidity 90%, 500 hours High temperature and high humidity environment 2: Temperature 80 ° C, humidity 90%, 100 hours Low temperature environment: -30 ° C, humidity 10%, 500 hours
5. Water-resistant environment: A wet tissue is placed on a laminated film at a temperature of 80 ° C. and a humidity of 90% and left for 30 minutes.
○: Change in polarization degree is 0.5% or less ×: Change in polarization degree is greater than 0.5%

(Moisture resistance)
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, The polarizing plates 1 to 3 obtained in Examples and Comparative Examples were re-bonded to the liquid crystal cell.
The reassembled liquid crystal display device was allowed to stand in a constant temperature and humidity chamber at 80 ° C. and 95% RH for 24 hours, and then left in a constant temperature and humidity chamber at 20 ° C. and 40% RH for 24 hours. Each layer of the protective layer and the laminated state between the polarizer and the protective layer are visually observed, and if the part that peels off and appears white is 1 mm or longer from the end of the polarizing plate, the length is less than 1 mm. Evaluated as ○ if any.

Claims (5)

A viewing-side protective layer comprising a thermoplastic resin, wherein elastic particles having a number average particle size of 2.0 μm or less are unevenly distributed in the central portion in the thickness direction of the viewing-side protective layer, and the average thickness is less than 100 μm; ,
With a polarizer,
It is laminated through an active energy ray-curable adhesive that does not contain a solvent.
A polarizing plate for liquid crystal display. A visible-side protective layer having an average thickness of less than 100 μm having a layer composed of a thermoplastic resin and elastic particles having a number average particle diameter of 2.0 μm or less and a layer composed of a thermoplastic resin laminated on both sides of the layer When,
With a polarizer,
It is laminated through an active energy ray-curable adhesive that does not contain a solvent.
A polarizing plate for liquid crystal display.   The polarizing plate for liquid crystal display according to claim 1, wherein the viewing-side protective layer contains an ultraviolet absorber. The polarizing plate for liquid crystal display according to any one of claims 1 to 3, wherein the viewing-side protective layer has a moisture permeability of 10 g · m ^-2 day ^-1 or more and 200 g · m ^-2 day ^-1 or less. A liquid crystal display provided with the polarizing plate as described in any one of Claims 1-4.