KR20100013812A - Light diffusion adhesive composition, polarizing plate and liquid crystal display device using the composition - Google Patents

Abstract

PURPOSE: A light diffusion adhesive composition is provided to suppress moire phenomenon caused by a prism sheet in application to a polarizing plate, to improve polarization and visibility of a liquid crystal display, and to prevent the degradation of brightness. CONSTITUTION: A light diffusion adhesive composition comprises an acrylic adhesive resin, crosslinking agent and light diffusion agent. The light diffusion agent is inorganic particles surface-treated with hydrophobic alkoxy silane compounds and has a crosslinking agent. The light diffusion agent has 5-25 micron average diameter. The difference (|n1-n2|) of refractive index (n1) and refractive index (n2) of the acrylic adhesive resin is 0.01-0.10.

Description

LIGHT DIFFUSION ADHESIVE COMPOSITION, POLARIZING PLATE AND LIQUID CRYSTAL DISPLAY DEVICE USING THE COMPOSITION

The present invention relates to a light-diffusion pressure-sensitive adhesive composition, a polarizing plate and a liquid crystal display device using the same, which is excellent in dispersibility and storage stability and can improve processability.

Generally, a liquid crystal display device (LCD) includes a liquid crystal panel including a liquid crystal cell containing liquid crystal, a polarizing plate stacked on both sides of the liquid crystal cell, and a backlight unit for providing light to the liquid crystal panel. .

The backlight unit is composed of a reflecting plate, a backlight light source, a light guide plate, a light diffusing member (diffusion plate, a diffusion sheet), a prism sheet, etc. as necessary in order to make the light of the light source uniform and to improve the brightness and utilization efficiency of the light. Depending on how they are arranged, they are classified as wedge, edge or direct light.

The edge type backlight unit 10 is a light emitting light source disposed on the side of the light guide plate, and as shown in FIG. 1, the light source 11, the reflective sheet 12, the light guide plate 13, the diffusion sheet 14, and the prism A sheet 15 and a protective sheet 16. As the light source 11, a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL) capable of generating light of a predetermined wavelength is used. The light guide plate 3 equalizes light incident through the light incident surface disposed on the side surface and emits light toward the liquid crystal panel disposed above the light exit surface, and the reflective sheet 12 is a rear surface of the light guide plate 13. The reflected light is reflected back to the light guide plate 13 to improve the light efficiency. The light emitted from the light exit surface of the light guide plate 13 is incident on the diffusion sheet 14, and the diffusion sheet 14 diffuses or condenses the incident light to uniform the luminance and widen the viewing angle. On the other hand, the light passing through the diffusion sheet 14 is sharply lowered in brightness, one or two prism sheets 15 are used to compensate for this. Since the prism sheet 15 refracts the light emitted from the diffusion sheet 14 and concentrates the light incident at a low angle toward the front side, the prism sheet 15 increases the luminance in the effective viewing angle range. The protective sheet 16 prevents scratching of the prism sheet 15, and functions to re-expand the viewing angle reduced by the prism sheet 15 within a predetermined range.

The direct type backlight unit 20 is a method in which a light emitting light source is disposed on the bottom of the liquid crystal panel. As shown in FIG. 2, the light source 21, the reflective sheet 22, the diffusion plate 27, the diffusion sheet 24, A prism sheet 25, a protective sheet 26 and a lower chassis 23. The diffusion plate 27 directs the light generated from the light source 21 toward the liquid crystal panel and is incident at a wide angle. The lower chassis 23 accommodates the light sources 21 and the reflective sheet 22. The rest of the configuration is the same as described for the edge type backlight unit.

Among the parts constituting the backlight unit, the prism sheet is used to improve luminance by refracting and condensing the light passing through the diffusion sheet or the diffusion plate, but the light passing through the prism sheet interferes with the ridge line and the curve of the prism sheet. A moire phenomenon, which is a phenomenon, occurs, which causes a decrease in display quality such as visibility of the liquid crystal display device. Therefore, the development of a liquid crystal display device without such a problem has been required.

In order to solve this problem, a method using a prism film having a serpentine shape (Korean Patent Laid-Open Publication No. 2007-0084410), a backlight unit further including a protective layer made of a diffusion particle and a resin base material under the base film of the prism sheet (Korean Patent Publication No. 2007-0109134) and the like have been proposed. According to this method, the moiré phenomenon is suppressed to some extent, but the manufacturing process is not complicated or economical, and the thickness of the backlight unit is also increased, making it difficult to meet the thinning required in recent years for the liquid crystal display device.

A method of using a diffusion adhesive has been proposed as another method for suppressing moiré phenomena and responding to thinning of liquid crystal displays. First, when the inorganic particles are used as the light diffusing agent, compatibility with the adhesive resin is deteriorated, and the particles are agglomerated with each other, causing precipitation. In addition, Korean Patent Laid-Open Publication No. 1999-0028342 (published on April 15, 1999) discloses a light diffusing pressure-sensitive adhesive having a light diffusing function by adding organic particles having different refractive indices to the pressure-sensitive adhesive as a method for improving the moiré phenomenon caused by a prism sheet. It is starting. However, while the organic particles have good compatibility with the pressure-sensitive adhesive resin, when the organic particles are added to the acrylic pressure-sensitive adhesive, the viscosity change is increased due to the swelling phenomenon of the organic particles, and as a result, the storage stability of the pressure-sensitive adhesive is reduced, resulting in processability. There is a problem of this deterioration.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a light-diffusion pressure-sensitive adhesive composition that can improve the processability by excellent dispersibility and storage stability of the pressure-sensitive adhesive composition.

In addition, it is an object of the present invention to provide a light-diffusion pressure-sensitive adhesive composition that can suppress the moiré phenomenon caused by the prism sheet when applied to the polarizing plate and at the same time improve the visibility of the liquid crystal display device by excellent polarization degree and preventing the lowering of luminance. .

Another object of the present invention is to provide a polarizing plate in which a light diffusion pressure sensitive adhesive layer made of the light diffusion pressure sensitive adhesive composition is laminated.

Another object of the present invention is to provide a liquid crystal display device having the polarizing plate on at least one side of a liquid crystal cell.

In order to achieve the above object, the present invention comprises an acrylic pressure-sensitive adhesive resin, a crosslinking agent and a light diffusing agent, the light diffusing agent provides a light-diffusion pressure-sensitive adhesive composition which is an inorganic particle containing a crosslinking agent and surface-modified with a hydrophobic alkoxysilane compound. .

In another aspect, the present invention provides a polarizing plate laminated with a light diffusion pressure-sensitive adhesive layer made of the light diffusion pressure-sensitive adhesive composition.

In another aspect, the present invention provides a liquid crystal display device having the polarizing plate on at least one side of the liquid crystal cell.

According to the present invention, the dispersibility and storage stability of the pressure-sensitive adhesive composition can be improved to improve workability, and when applied to a polarizing plate, it is possible to suppress the moiré phenomenon caused by the prism sheet, and at the same time, the degree of polarization is excellent and the luminance is prevented from deteriorating. An improved light diffusing pressure-sensitive adhesive composition, a polarizing plate and a liquid crystal display device using the same may be provided to improve visibility of a display device.

The present invention has excellent storage stability, can suppress the moire phenomenon, at the same time excellent polarization degree and improved brightness to improve the visibility of the liquid crystal display device by preventing the lowering of the brightness, polarizing plate and liquid crystal display using the same Relates to a device.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The light-diffusion adhesive composition of this invention contains an acrylic adhesive resin, a crosslinking agent, and a light-diffusion agent.

As the acrylic pressure sensitive adhesive resin, a copolymer of a monomer having a functional group capable of crosslinking with a (meth) acrylate monomer having 1 to 14 carbon atoms of an alkyl group and a crosslinking agent as the acrylic copolymer can be used. In this case, "(meth) acrylate" means both acrylate and methacrylate.

Specific examples of the (meth) acrylate monomer having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t -Butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth ) Acrylate, n-tetradecyl (meth) acrylate, pentafluorooctylacrylate, 6- (1-naphthyloxy) -1-hexyl acrylate, and the like, and these may be used alone or in combination of two or more thereof. Can be used.

The (meth) acrylate monomer having 1 to 14 carbon atoms is preferably included in 50 to 99% by weight relative to the total monomer content (100% by weight) used to prepare the acrylic copolymer.

The monomer having a functional group capable of crosslinking with the crosslinking agent has a function of imparting cohesion force or adhesive strength by chemical bonding so as not to cause cohesive breakage of the pressure sensitive adhesive under high temperature or humidity conditions. For example, a sulfonic acid group-containing monomer, Phosphoric acid group containing monomer, cyano group containing monomer, vinyl esters, aromatic vinyl compound, carboxyl group containing monomer, acid anhydride group containing monomer, hydroxy group containing monomer, amide group containing monomer, amino group containing monomer, imide group containing monomer, epoxy group containing monomer and ether A group containing monomer etc. can be used and these can be used individually or in combination of 2 or more types.

Examples of the sulfonic acid group-containing monomer include styrenesulfonic acid, allylsulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) ) Acryloyloxy naphthalene sulfonic acid, sodium vinyl sulfonate, etc. are mentioned.

2-hydroxyethyl acryloyl phosphate is mentioned as said phosphoric acid group containing monomer.

(Meth) acrylonitrile is mentioned as said cyano group containing monomer.

Examples of the vinyl esters include vinyl acetate, vinyl propionate and vinyl laurate.

Examples of the aromatic vinyl compound include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes.

Examples of the carboxyl group-containing monomers include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and isocrotonic acid.

As said acid anhydride containing monomer, maleic anhydride, itaconic anhydride, these acid anhydrides, etc. are mentioned.

As the hydroxy group-containing monomer, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methylacrylate, N-methyl All (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, etc. are mentioned.

Examples of the amide group-containing monomer include (meth) acrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N'-methylenebisacrylamide, N, N- dimethylaminopropyl (meth) acrylamide, diacetone acrylamide, etc. are mentioned.

Examples of the amino group-containing monomers include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and (meth) acryloyl morpholine. Can be mentioned.

Cyclohexyl maleimide, isopropyl maleimide, N-cyclohexyl maleimide, itaciconimide etc. are mentioned as said imide group containing monomer.

Examples of the epoxy group-containing monomers include glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, allyl glycidyl ether, and the like.

The ether group-containing monomers include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, and acryloyl. Morpholine, and the like.

The monomer having a crosslinkable functional group is preferably contained in 1 to 50% by weight relative to the total monomer content (100% by weight) used in the production of the acrylic copolymer.

The acrylic copolymer composed of the above components can be prepared by conventional methods such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization and emulsion polymerization, and preferably by solution polymerization.

The acrylic copolymer has a weight average molecular weight (polystyrene equivalent) measured by gel permeation chromatography (GPC) method is usually 50,000 to 2,000,000, preferably 100,000 to 1,800,000, more preferably 500,000 to 1,500,000 to be.

The crosslinking agent is used to reinforce the cohesive force of the pressure-sensitive adhesive composition by appropriately crosslinking the acrylic copolymer, and an isocyanate compound, an epoxy compound, a melamine resin, an aziridine compound, or the like may be used. Preferably, an isocyanate compound or an epoxy compound is used. Can be. These can be used individually or in combination of 2 or more types.

As said isocyanate compound, tolylene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, 2, 4- diphenyl methane diisocyanate, 4, 4- diphenyl methane diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate And naphthalene diisocyanate.

Examples of the epoxy compound include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N, N, N ', N'-tetraglycidyl diamine, glycerin diglycidyl ether, and 1 , 3-bis (N, N- diglycidylaminomethyl) cyclohexane, etc. are mentioned.

Hexamethylol melamine is mentioned as said melamine type resin.

Examples of the aziridine-based compound include N, N'-toluene-2,4-bis (1-aziridinecarboxide) and N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxa) Id), triethylene melamine, bisisoprotaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, etc. are mentioned.

The crosslinking agent is preferably included in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the acrylic pressure-sensitive adhesive resin (based on the solid content). If the content is less than 0.01 parts by weight, the adhesive force or cohesive force of the pressure-sensitive adhesive is not good, and if it exceeds 15 parts by weight, the compatibility is reduced, the surface migration may occur and the crosslinking reaction is too advanced to reduce the adhesive strength.

In addition, as said crosslinking agent, an ultraviolet curable polyfunctional (meth) acrylate type monomer can also be used. As a specific example, 1, 4- butanediol di (meth) acrylate, 1, 6- hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethyleneglycol di (meth) acrylate, dicyclo Fentanyldi (meth) acrylate, caprolactone modified dicyclopentenyldi (meth) acrylate, ethylene oxide modified phosphoric acid di (meth) acrylate, di (acryloxyethyl) isocyanurate, allylated cyclohexyldi (meth) Bifunctional such as) acrylate, dimethylol dicyclopentanediacrylate, ethylene oxide modified hexahydrophthalic acid diacrylate, tricyclodecane dimethanol acrylate, neopentyl glycol modified trimethylolpropanediacrylate and adamantane diacrylate Acidic monomers; Trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane Trifunctional monomers such as tri (meth) acrylate and tris (acryloxyethyl) isocyanurate; Tetrafunctional monomers such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; Pentafunctional monomers such as propionic acid-modified dipentaerythritol penta (meth) acrylate; And 6 functional monomers, such as caprolactone modified dipentaerythritol hexa (meth) acrylate, etc. are mentioned. These can be used individually or in combination of 2 or more types.

The ultraviolet curable multifunctional (meth) acrylate monomer is preferably included in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the acrylic pressure-sensitive adhesive resin (based on the solid content).

The ultraviolet curable polyfunctional (meth) acrylate-based monomer may be used together with a photopolymerization initiator that generates radicals or cations by irradiation with ultraviolet rays.

Specific examples of the photoinitiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2, 2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenylketone , 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl Ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-amino Anthraquinone, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2-chlorothioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyl dimethyl ketal, acetophenone dimethyl Ketal, p-dimethylaminobenzoic acid LE and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and the like, and these may be used alone or in combination of two or more. The photopolymerization initiator may be included in an amount of usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the acrylic adhesive resin (based on the solid content).

The light diffusing agent is an inorganic particle containing a crosslinking agent and surface modified with a hydrophobic alkoxysilane compound.

The inorganic particles are pores containing pores, specific examples selected from the group consisting of silica, potassium carbonate, barium sulfate, titanium dioxide, aluminum hydroxide, glass, talc, mica, white carbon, magnesium oxide and zinc oxide. It may be one or more, and it is particularly preferable to use silica.

As the inorganic particles, those having a spherical shape, irregularities, and porous shapes may be used. However, in the present invention, it is preferable to use spherical, uneven, porous particles. In particular, the porous particles contain a large amount of pores, so that the crosslinking agent can be more easily adsorbed by the surface treatment of the silane coupling agent, and when mixed with the acrylic adhesive resin, the acrylic adhesive resin penetrates into the particles. Thus, light scattering occurs several times, and as a result, the moiré phenomenon caused by the prism sheet can be more efficiently improved.

The pore size is preferably 0.05 to 20 nm in average diameter, and the pore size is more preferably 2 to 10 times the molecular size of the crosslinking agent so that the crosslinking agent containing the inorganic particles can be easily adsorbed in the pores. In addition, it is preferable that the pore volume is 0.1 to 1.1 dl / g, and the specific surface area is 10 to 1,000 m 2 / g for adsorption of an appropriate content of the crosslinking agent.

The inorganic particles may be pretreated with a silane coupling agent to facilitate physical adsorption of the crosslinking agent. Through such pretreatment, the surface of the pores present in the inorganic particles is changed from hydrophilic to hydrophobic, and thus, the crosslinking agent can be more easily adsorbed, thereby improving compatibility with the acrylic pressure-sensitive adhesive resin.

Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4-epoxycyclohexyl Epoxy group-containing silane coupling agents such as ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, etc. Amino group-containing silane coupling agent; (Meth) acryl-group containing silane coupling agents, such as 3-acryloxypropyl trimethoxysilane and 3-methacryloxypropyl triethoxysilane; And isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane. In addition, the content of the silane coupling agent may be 0.1 to 10 parts by weight, preferably 0.3 to 3.0 parts by weight based on 100 parts by weight of the inorganic particles.

The crosslinking agent contained in the inorganic particles is to increase the bonding strength of the acrylic pressure-sensitive adhesive resin and the light diffusing agent and to disperse the inorganic particles without aggregation with each other, and has a multifunctional group capable of causing a crosslinking reaction through exposure to a heat source. If it is a crosslinking agent, the kind in particular will not be restrict | limited. Specific examples include acrylic acid or methacrylic acid esters of diols such as butanediol diacrylate; Acrylic or methacrylic esters of triols such as glycerol; And acrylic or methacrylic acid esters of tetrol, such as pentaerythritol. Moreover, polyvinyl crosslinking agents, such as substituted or unsubstituted divinylbenzene, bifunctional urethane acrylate, or mixtures thereof, etc. are mentioned. The crosslinking agent may be used in an amount compatible with the retention of known uses and adhesive properties, and at this time, the molecular weight of the crosslinking agent, the degree of the polyfunctional functional group, the content, and the like may be considered. In addition, the content of the crosslinking agent may be 1 to 50 parts by weight based on 100 parts by weight of the inorganic particles.

The hydrophobic alkoxysilane compound is attached to the inorganic particles to impart hydrophobicity to improve compatibility with acrylic pressure-sensitive adhesive resins, including tridecyltrimethoxysilane, tridecylmethyldimethoxysilane, undecyltrimethoxysilane and diound. Alkyl alkoxysilanes such as sildimethoxysilane, octadecyldimethylmethoxysilane, octadecyldimethylethoxysilane, decyltrimethoxysilane, hexyltrimethoxysilane and hexylmethyldimethoxysilane; Alkenylsilanes such as octenyltrimethoxysilane and hexenylmethyldimethoxysilane; Aromatic alkoxysilanes such as phenyltriethoxysilane, benzyltriethoxysilane, phenylethyltriethoxysilane and quaternary butylpentyldimethylmethoxysilane; And alkoxysilanes containing cyclic hydrocarbon functional groups such as bicycloheptenyltriethoxysilane, bicyclicheptanylmethyldimethoxysilane, and cyclohexyldimethylethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, etc. Epoxy group-containing silane coupling agent; 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, etc. Amino group-containing silane coupling agent; (Meth) acryl-group containing silane coupling agents, such as 3-acryloxypropyl trimethoxysilane and 3-methacryloxypropyl triethoxysilane; And isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane, and one or more selected from the group consisting of, but not limited thereto. In addition, the content of the hydrophobic alkoxysilane compound may be 3 to 50 parts by weight based on 100 parts by weight of the inorganic particles.

The light diffusing agent as described above may be prepared by physically adsorbing the crosslinking agent to the inorganic particles and then surface modifying the hydrophobic alkoxysilane compound. Specifically, the surface of the pores present in the inorganic particles is treated by a conventional surface treatment method using a silane coupling agent. Subsequently, the inorganic particles are impregnated in the solution obtained by dissolving the crosslinking agent in the nonpolar solvent, and then the nonpolar solvent is removed to physically adsorb the crosslinking agent to the inorganic particles. In this case, as the nonpolar solvent, ethyl acetate, toluene, ether, acetone, methyl ethyl ketone, benzene, chloroform, hexane or methylene chloride may be used in a volume of 2-3 times the pore volume of the inorganic particles. Next, an inorganic particle having a crosslinker adsorbed is mixed with a polar solvent and a hydrophobic alkoxysilane compound to prepare a slurry, and then water and a catalyst are added to adjust the pH and subjected to surface modification at a temperature below the melting point of the crosslinker. The light diffusing agent can be prepared by sufficiently reacting for an unreacted product of the hydrophobic alkoxysilane compound and then separating the filtrate and washing with a polar solvent. In this case, as the polar solvent, monohydric or dihydric alcohols such as ethanol, methanol and isopropyl alcohol may be used. In addition, when using an acid catalyst such as hydrochloric acid, strong acid such as nitric acid, organic acid such as acetic acid, formic acid, etc., the pH may be 2 to 5, when using caustic soda, ammonia water, etc., the pH is 8 to 10 days Can be.

The light diffusing agent of the present invention having the above structure has a swelling caused by aging caused when using organic particles such as conventional acrylic resin, polystyrene resin, styrene-acrylic copolymer resin, polyethylene resin, epoxy resin ( swelling) and thereby increase the viscosity and lower the storage stability, and when using the inorganic particles can be solved at the same time the problem that precipitation occurs due to deterioration of compatibility with acrylic resin.

The light diffusing agent may have an average diameter of 3 to 30 μm, and preferably 5 to 25 μm. In addition, from the viewpoint of the uniformity of the light-diffusion pressure-sensitive adhesive layer made of a composition containing particles as the light diffusing agent, it is generally preferable that the average diameter of the particles is uniform. When the average diameter is less than 3 μm, the dispersibility with the acrylic pressure sensitive adhesive becomes poor, and when the small particles are laminated in the multilayer in the pressure sensitive adhesive layer, backscattering may occur and the polarization degree and the brightness may be lowered. Moreover, when the average diameter exceeds 30 micrometers, there exists a possibility that the thickness process margin of a particle | grain addition adhesive layer may fall, and adhesive durability may fall.

Since the light diffusing agent as described above is in the form of a powder, when added directly to a highly viscous acrylic adhesive resin, dispersion stability is lowered, and thus the light diffusing agent particles are not uniformly distributed in the adhesive resin. Therefore, it is preferable to disperse | distribute a light-diffusion agent to a solvent completely, and to add to an adhesive resin. The solvent for dispersing the light diffusing agent is not particularly limited in kind. For example, the same solvent as that used in the production of the acrylic pressure-sensitive adhesive resin may be used, and ethyl acetate, toluene, as acetate, benzene or ketone solvents having excellent dispersibility and solvent resistance to inorganic or organic particles. Xylene or methyl ethyl ketone can also be used.

The light diffusing agent is preferably included in an amount of 5 to 50 parts by weight, more preferably 20 to 40 parts by weight, based on the acrylic pressure-sensitive adhesive resin (based on the solid content). If the content is less than 5 parts by weight, the haze value becomes smaller and the moire phenomenon becomes stronger. If the content exceeds 50 parts by weight, the haze value becomes large, the polarization degree is lowered, and the brightness and adhesion durability are lowered.

In the present invention, the difference between the refractive index (n ₁₎ and the light-diffusing material refractive index (n ₂₎ of the acrylic pressure sensitive adhesive resin (| n ₁ -n ₂ |) may be in the range of 0.01 to 0.15, preferably 0.01 to 0.1 More preferably, they are 0.04 to 0.07. If the difference in refractive index is less than 0.01, a large amount of light diffusing agent should be added to the acrylic pressure-sensitive adhesive resin, so that the adhesion durability is lowered.

The light-diffusion pressure-sensitive adhesive composition comprising the above components is 0.005 to 100 parts by weight of a conventional silane coupling agent based on 100 parts by weight of an acrylic pressure-sensitive adhesive resin (solid content basis), if necessary, in order to improve adhesion between the liquid crystal cell or the substrate. 5 parts by weight may be further included.

In addition, the light diffusing pressure-sensitive adhesive composition is a tackifying resin, antioxidant, corrosion inhibitor, leveling agent, surface lubricant, dye in order to adjust the adhesion, cohesion, viscosity, elastic modulus, glass transition temperature, antistatic properties, etc. required according to the application It may further include additives such as pigments, antifoams, fillers, antistatic agents or light stabilizers.

Polarizing plate of the present invention is characterized in that the light-diffusion pressure-sensitive adhesive layer made of the light-diffusion pressure-sensitive adhesive composition is laminated.

The polarizing plate includes a polarizer (or “polarizing film”), and on one side of the polarizer, a polarizer protective film for protecting the polarizer, a pressure-sensitive adhesive layer and a release film, which are combined with a liquid crystal cell, are sequentially stacked, and the polarizer On the other side of the polarizer protective film is provided with a multi-layer structure.

As said polarizer, the thing in which the dichroic dye was adsorption-oriented to the film which consists of polyvinyl alcohol-type resin can be used. As a polyvinyl alcohol-type resin which comprises a polarizer, the copolymer of polyvinyl acetate which is a homopolymer of vinyl acetate, and vinyl acetate and the other monomer copolymerizable with this can be used. In this case, examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and acrylamides having an ammonium group. The thickness of the polarizer is not particularly limited and can be produced in a conventional thickness.

The polarizer protective film is preferably excellent in transparency, mechanical strength, thermal stability, moisture shielding, isotropy, etc., for example, polyester-based films such as polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate; Cellulose films such as diacetyl cellulose and triacetyl cellulose; Polycarbonate film; Acrylic films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene films such as polystyrene and acrylonitrile-styrene copolymers; Polyolefin-based films such as polyethylene, polypropylene, cyclo- or polyolefin-based films having a norbornene structure, and ethylene propylene copolymers; Polyimide film; Polyether sulfone-based film; A sulfone type film etc. can be used, The thickness of these is also not specifically limited.

The release film is a film for protecting the light diffusion pressure-sensitive adhesive layer, the type is not particularly limited as long as it is a film commonly used in the art. Specific examples include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate Polyolefin-based films such as copolymers and ethylene-vinyl alcohol copolymers; Polyester-based films such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; Polyamide films such as polyacrylate, polystyrene, nylon 6 and partially aromatic polyamide; Polyvinyl chloride film; Polyvinylidene chloride film; Or polycarbonate films. These can also be used by appropriately releasing a silicone, fluorine, silica powder or the like.

The method of laminating the light diffusion adhesive layer on the polarizing plate is not particularly limited as long as it is a method commonly used in the art. For example, the pressure-sensitive adhesive composition may be flow casted on a polarizer protective film, and a bar-coater, air knife, gravure, reverse roll, kiss roll, Using a coating method such as spray or blade method can be applied directly in a suitable development method, dried and laminated. In addition, after the pressure-sensitive adhesive layer is formed on the silicone-coated release film by the same coating method as described above, the pressure-sensitive adhesive sheet may be laminated on the polarizer protective film using a roll pressing device. In this case, when the pressure-sensitive adhesive composition contains an ultraviolet curable polyfunctional (meth) acrylate monomer as a crosslinking agent, it is preferable to irradiate ultraviolet rays after applying the pressure-sensitive adhesive composition or laminating it on the polarizer protective film using a roll pressing device. Do.

The thickness of the light diffusion pressure-sensitive adhesive layer can be adjusted according to the adhesive force, it is preferably 3 to 100㎛, more preferably 10 to 50㎛.

The light diffusion pressure-sensitive adhesive layer has a haze value of 30 to 70% and a transmission sharpness value of 20 to 120, more preferably a haze value of 40 to 70% and a transmission sharpness value of 20 to 100. If the haze value is less than 30% and the transmittance sharpness value is greater than 120, light diffusion decreases and the moiré phenomenon occurs. If the haze value is greater than 70% and the transmittance brightness value is less than 20, due to the problem of backscattering The polarization degree is lowered.

In addition, the light-diffusion pressure-sensitive adhesive layer is less than 20%, preferably less than 15% brightness reduction rate compared to the pressure-sensitive adhesive layer is not added. If the luminance reduction rate is 20% or more, the intensity of light generated from the backlight unit should be increased, and as a result, there is a problem of increase in power consumption and heat generation. In particular, notebook PCs have a problem of shortening battery life due to increased power consumption.

In addition, the light-diffusion pressure-sensitive adhesive layer is preferably a polarization degree of 99.94% or more, more preferably 99.95% or more. If the degree of polarization is in the above range, there is no significant reduction in contrast, and thus there is an effect of realizing a clear image.

Polarization degree (P) = [(T ₁ -T ₂ ) / (T ₁ + T ₂ )] ^1/2

(In formula, T <_1> is the parallel transmittance obtained when a pair of polarizing plate is arrange | positioned in parallel state, and T <_2> is the orthogonal transmittance obtained when a pair of polarizing plate is arrange | positioned in the state orthogonal to an absorption axis. )

3 is a cross-sectional view showing the polarizing plate of the present invention. As shown in FIG. 3, in the polarizing plate 30 of the present invention, polarizer protective films 31 and 33 are stacked on both surfaces of the polarizer 32, and the polarizer protective film 31 on the portion of the polarizer 32 and which is affixed with the liquid crystal cell. It has a structure in which the light-diffusion adhesive layer 34 is laminated | stacked on. Figure 3 shows an example of the polarizing plate of the present invention, it is obvious that it is applicable to a polarizing plate in which a polarizer protective film is laminated on only one surface of the polarizer.

The polarizing plate as described above can be applied to all conventional liquid crystal display devices, It can be used as an upper plate and a lower plate polarizing plate. In particular, it is applied more preferably as a lower polarizing plate of a transmissive liquid crystal display device. When a pressure-sensitive adhesive layer having a light diffusing function is applied to the upper plate of the liquid crystal display device, it is difficult to form a clear image because distorted light (moire phenomenon) caused by the prism sheet passes through the liquid crystal cell. Therefore, before transmitting the distorted light to the liquid crystal cell, it is preferable to solve the distortion of the light through the light diffusion adhesive layer of the lower plate, and then transmit the light to the liquid crystal cell.

In addition, the liquid crystal display device of the present invention is characterized in that the polarizing plate on which at least one surface of the liquid crystal cell is laminated the light diffusion adhesive layer is provided.

4 is a cross-sectional view showing a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 4, in the liquid crystal display device 100 of the present invention, a light diffusing pressure sensitive adhesive layer is laminated on the liquid crystal cell 50, the upper polarizing plate 40 on the viewing side of the liquid crystal cell 50, and the backlight unit side. The liquid crystal panel in which the lower polarizing plate 30 is stacked, and the direct type backlight unit 20 are included.

In the present invention, since the liquid crystal display device is well known to those skilled in the art of the present invention, a detailed description of each configuration is omitted.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

In the following Synthesis Examples, Examples, and Comparative Examples, "%" and "parts" indicating contents are by weight unless otherwise specified.

Synthesis Example 1 Preparation of Acrylic Copolymer

A 4-neck jacket reactor (1L) was equipped with a stirrer, a thermometer, a reflux cooling tube, a dropping lot, and a nitrogen gas introduction tube. Nitrogen gas was added to the reactor to replace the same, and then 120 parts of ethyl acetate, n- 98 parts of butyl acrylates, 0.5 parts of acrylic acid, and 1.4 parts of # 2-hydroxyethyl acrylate were thrown in, and the reactor external temperature was heated up at 50 degreeC. Subsequently, a solution in which 0.1 part of 2,2'-azobisisobutyronitrile (AIBN) was completely dissolved in 10 parts of ethyl acetate was added dropwise to the reactor. After the reaction was continued for an additional 5 hours while maintaining the jacket outside temperature at 50 ° C, the reaction was terminated and diluted with ethyl acetate to obtain an acrylic copolymer solution having a solid content of 20%. The weight average molecular weight by GPC of the prepared copolymer solution was 1,500,000 and the refractive index was 1.42.

Preparation Example 1 Preparation of Light Diffusion Agent A

10 kg of silica (manufactured by ABC Nanotech Co., Ltd.) having a specific surface area of 300 m 2 / g, an average diameter of 20 µm, and a void volume of 0.5 µg / g was weighed. 0.3 kg of aminosilane A6070 (manufactured by APR Silane Technology) was dissolved in 10 L of ethanol, and the silica was added thereto to prepare a slurry. Acetic acid was added to the catalyst while stirring the slurry at room temperature, the pH of the slurry was adjusted to 5, the reaction was performed for 5 hours, filtered, washed three times with 3 L of ethanol, and dried and recovered for 24 hours in a vacuum dryer maintained at 70 ° C. . In order to physically adsorb the crosslinking agent to the recovered silica, a gravity mixer (F-20, manufactured by Seji Industries Co., Ltd.) equipped with a solvent supply device, an indirect heating device, and a vacuum solvent recovery device was used. Once the total amount of silica recovered in the gravity-free mixer was added, 1 kg of a crosslinking agent, Ebecryl ^™ 270 (urethane acrylate having an average molecular weight of 1500, manufactured by Radcure Specialty Co., Ltd.) was dissolved in 10 L of ethyl acetate to prepare a crosslinking agent solution, and the solvent It was placed in the feeder and wetted at room temperature while adding to silica at a rate of 0.2 L / min while maintaining the rotor speed of the zero gravity mixer at 100 rpm. After the crosslinker solution was completely added, mixing was continued for 1 hour. Then, the temperature of the mixer was raised to 50 ° C., and the valve of the vacuum solvent recovery device was opened to recover ethyl acetate as a solvent. The sample was taken in the middle, and the solvent recovery was stopped when the residual amount of solvent was 1% by weight or less using an infrared gravimetric analyzer. The crosslinker, Ebecryl ^™ 270, was adsorbed.

For hydrophobic modification of the obtained silica surface, the total amount recovered was gradually added to a solution in which 2 kg of alkoxysilane Z-6070 (manufactured by Dow Corning) was dissolved in a mixed solvent of 2 kg of ethanol and 20 kg of ion-exchanged water, and then at 150 rpm. Stirring at a rate produced a slurry. 25 wt% aqueous ammonia was added to the prepared slurry to adjust the pH of the slurry to 8-9, and reacted at room temperature for 24 hours. After completion of the reaction, the mixture was filtered, washed three times with 2.5 L of ethanol, and dried for 24 hours in a vacuum drier maintained at 50 ° C to obtain about 12 kg of silica light diffusing agent containing a crosslinking agent and surface-modified with a hydrophobic alkoxysilane compound.

Preparation Example 2 Preparation of Light Diffusion Agent B

A light diffusing agent B was prepared in the same manner as in Preparation Example 1, except that silica having an average diameter of 8 μm was used.

Preparation Example 3 Preparation of Light Diffusion Agent C

A light diffusing agent C was prepared in the same manner as in Preparation Example 1, except that silica having an average diameter of 3 μm was used.

Preparation Example 4 Preparation of Light Diffusion Agent D

A light diffusing agent D was prepared in the same manner as in Preparation Example 1, except that silica having a specific surface area of 100 m 2 / g, an average diameter of 8 μm, and a pore volume of 0.05 μg / g was used.

Example 1

100 parts of acrylic copolymer resin (based on solids content) prepared in Synthesis Example 1, 0.8 parts of trimethylolpropane-modified tolylene diisocyanate (Coronate L, manufactured by Nippon Polyurethane Industry), 3-glycidoxypropyltrimethoxy 0.15 parts of silane (KBM-403) and 30 parts of light diffusing agent A (average diameter: 20 μm, refractive index: 1.46, manufactured by ABC Nanotech Co., Ltd., product name: Si ⁺ 120 MSMC) prepared in Preparation Example 1 were dispersed in an ethyl acetate solvent. The solution was added and diluted to an final concentration of 13% using ethyl acetate to prepare a pressure-sensitive adhesive composition.

A part of the prepared pressure-sensitive adhesive composition was stored for pot life test, and the remaining pressure-sensitive adhesive composition was dried on a plurality of PET films (25 cm × 20 cm) coated with a release agent using an applicator, and then the thickness of the pressure-sensitive adhesive was increased. Each was applied to 30㎛, and dried for 3 minutes in a forced circulation hot air dryer of 100 ℃ oven to prepare a light-diffusion adhesive sheet. Some of these sheets are manufactured by laminating other release films on the pressure-sensitive adhesive layer and laminating them to form a non-carrier film (NCF), and measure thermostatic humidity (60%, 25) for measuring physical properties such as haze, transmission sharpness and moiré phenomenon. ℃, and the remaining some sheets were adhered to a conventional polarizing plate to evaluate the optical properties (polarization degree, luminance).

Example 2

35 parts of the light diffusing agent B (average diameter: 8 탆, refractive index: 1.46, manufactured by ABC Nanotech Co., Ltd., product name: Si ⁺ 190Z) prepared in Preparation Example 2 were used so that the thickness of the adhesive was 15 탆 after drying. Except that was carried out in the same manner as in Example 1.

Example 3

Example 1, except that 35 parts of the light diffusing agent C (average diameter: 3㎛, refractive index: 1.46, manufactured by ABC Nanotech Co., Ltd.) manufactured in Preparation Example 3 were made to have an adhesive thickness of 15 μm after drying. It was carried out in the same manner as.

Example 4

Example 1, except that 35 parts of the light diffusing agent D (average diameter: 8㎛, refractive index: 1.55, manufactured by ABC Nanotech Co., Ltd.) manufactured in Preparation Example 4 were made to have an adhesive thickness of 15 µm after drying. It was carried out in the same manner as.

Comparative Example 1

35 parts of silica particles (average diameter: 8 µm, refractive index: 1.46, manufactured by ABC-C Nanotech Co., Ltd.) without containing a crosslinking agent as a light diffusing agent were used, and the thickness of the adhesive was 15 µm after drying. It carried out in the same manner as in Example 1.

Comparative Example 2

40 parts of polymethyl methacrylate organic particles (average diameter: 10 μm, refractive index: 1.49, manufactured by Soken Chemical Co., Ltd., product name: MX-1000) were used as the light diffusing agent, except that the adhesive was 15 μm thick after drying. Was carried out in the same manner as in Example 1.

division Copolymer Light diffusing agent Refractive index difference | (n ₁ -n ₂ ) | Adhesive thickness (㎛) content Refractive Index (n ₁ ) Inorganic particles Surface modification Organic particles Particle Diameter (㎛) content Refractive Index (n ₂ ) Example 1 100 1.42 Silica U - 20 30 1.46 0.04 30 Example 2 100 1.42 Silica U - 8 35 1.46 0.04 15 Example 3 100 1.42 Silica U - 3 35 1.46 0.04 15 Example 4 100 1.42 Silica U - 8 35 1.55 0.13 15 Comparative Example 1 100 1.42 Silica radish - 8 35 1.46 0.04 15 Comparative Example 2 100 1.42 - - PMMA 10 40 1.49 0.07 15

Test Example

The physical properties of the light-diffusion pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet and polarizing plate prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 2 below.

(1) haze

After cutting the manufactured non-carrier film (NCF) sheet into 4cm × 4cm size, it uses a haze meter (HZ-1, manufactured by Suga Test Instrument Co., Ltd.) to comply with JIS K 7361-1. It measured based on and calculated by following formula (2).

Haze (%) = diffused light / total transmitted light × 100

(2) Transmission sharpness

The prepared non-carrier film (NCF) sheet was cut to a size of 4 cm × 4 cm and measured using a transmission sharpness meter (ICM-1T, manufactured by Suga Test Instrument Co., Ltd.). In this case, the transmission sharpness can be measured using an optical comb using four kinds of optical combs having a width ratio of the dark portion and the wrist ratio of 1: 1, and the widths of which are 0.125 mm, 0.5 mm, 1.0 mm, and 2.0 mm, respectively. JIS K 7105 By the transmission method according to the regulations, the incidence direction of light was measured by using four kinds of optical combs in the vertical direction, and the sum of these was taken as the sum of the transmission sharpness.

(3) moiré phenomenon

After manufacturing a non-carrier film (NCF) -shaped sheet on the prism sheet of the backlight unit in which the reflecting plate, the light source, the diffusion plate, and the prism sheet were sequentially stacked, the intensity of occurrence of moiré phenomenon resulting from the prism sheet was measured. It judged visually and evaluated based on the following criteria.

◎: Moiré phenomenon does not occur at all

○: slight moiré

△: moiré partially occurs

×: many moire phenomena occur

(4) polarization degree

The polarizing plate on which the prepared light-diffusion pressure-sensitive adhesive sheet was laminated was cut to a size of 4 cm × 4 cm and measured using an ultraviolet visible light spectrometer (VAP-7070, manufactured by JASCO). At this time, the degree of polarization is defined by Equation 1 described above.

(5) luminance decrease rate

The polarizing plate (lower plate) in which the light-diffusion adhesive layer was laminated was bonded to the edge type backlight unit as shown in FIG. 1, and measured using the luminance meter (CA-210, manufactured by KONIKA MINOLTA). At this time, the luminance reduction rate was shown based on the luminance value of the polarizing plate (reference example) in which the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition was not used.

(6) storage stability

The initial viscosity of the prepared pressure-sensitive adhesive composition (13%) and the viscosity after being left for 7 days were measured, and the change in viscosity was measured to evaluate storage stability. At this time, the viscosity was measured using a viscometer (Brookfield LVDV-II + Form B (spindle no. 2, 30rpm)).

○: Viscosity / initial viscosity after 7 days <2

Δ: viscosity / initial viscosity <2 after 7 days

×: viscosity / initial viscosity after 3 ≦ 7 days

(7) dispersibility

The degree of dispersion of the light diffusing agent in the prepared light diffusing pressure-sensitive adhesive composition was visually observed and evaluated based on the following criteria.

(Circle): Good dispersion of the light diffusing agent does not occur.

△: partial precipitation of light diffusing agent occurs

X: A lot of precipitation of a light diffusing agent generate | occur | produces, and dispersibility is not good

division Dispersibility Storage stability Haze (%) Transmission clarity Moire Polarization degree (%) (improvement of visibility) Luminance reduction rate (%) Example 1 ○ ○ 50 42 ○ 99.970 10 Example 2 ○ ○ 55 64 ○ 99.969 15 Example 3 △ ○ 50 221 △ 99.934 20 Example 4 ○ ○ 89 20 ○ 99.928 40 Comparative Example 1 × ○ - - - - - Comparative Example 2 ○ × 55 89 ○ 99.970 10

As shown in Table 2, it was confirmed that the light-diffusion pressure-sensitive adhesive composition of Examples 1 to 4 according to the present invention is excellent in dispersibility and little change in viscosity and excellent in storage stability. In particular, in Examples 1 to 2, the average diameter and the refractive index of the light diffusing agent may also be adjusted to improve the moiré phenomenon when applied to the pressure sensitive adhesive sheet and the polarizing plate. In the case of Example 3, the moire phenomenon and the transmission clarity were slightly decreased by using a light diffusing agent having a relatively small average diameter, and in Example 4, the difference in refractive index between the pressure-sensitive adhesive resin and the light diffusing agent became relatively large, and the haze increased. The transmittance sharpness was lowered, and the polarization degree was slightly decreased.

On the other hand, in Comparative Example 1 using silica particles as a light diffusing agent, the dispersion of the light diffusing agent is not good, and the particles are agglomerated, which causes precipitation to be difficult to apply to the sheet and the polarizing plate. The used comparative example 2 had the largest change in viscosity of the pressure-sensitive adhesive composition, and greatly reduced storage stability.

1 is a cross-sectional view showing an edge type backlight unit;

2 is a cross-sectional view illustrating a direct type backlight unit;

3 is a cross-sectional view showing a polarizing plate laminated with a light diffusion adhesive layer according to an embodiment of the present invention,

4 is a cross-sectional view illustrating a liquid crystal display device according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: edge type backlight unit 20: direct type backlight unit

11, 21: light source 12, 22: reflector

13: light guide plate 14, 24: diffusion sheet

15, 25: prism sheet 16, 26: protective sheet

23: lower chassis 27: diffuser plate

30: polarizing plate (bottom plate) 40: polarizing plate (top plate)

31, 33, 41, 43: polarizer protective film

32, 42: polarizer 34: light diffusion adhesive layer

44: adhesive layer 50: liquid crystal cell

100: liquid crystal display device

Claims (10)

An acrylic pressure-sensitive adhesive resin, a crosslinking agent and a light diffusing agent, wherein the light diffusing agent is an inorganic particle containing a crosslinking agent and surface-modified with a hydrophobic alkoxysilane compound. The light diffusing pressure sensitive adhesive composition of claim 1, wherein the light diffusing agent has an average diameter of 5 to 25 μm. The light-diffusion pressure-sensitive adhesive composition of claim 1, wherein a difference (| n ₁ -n ₂ |) between the refractive index (n ₁ ) of the acrylic adhesive resin and the refractive index (n ₂ ) of the light diffusing agent is 0.01 to 0.10. The light diffusing pressure sensitive adhesive composition according to claim 1, wherein the inorganic particles are at least one member selected from the group consisting of silica, potassium carbonate, barium sulfate, titanium dioxide, aluminum hydroxide, glass, talc, mica, white carbon, magnesium oxide, and zinc oxide. . The method of claim 1, wherein the crosslinking agent contained in the light diffusing agent includes acrylic or methacrylic acid of diols, triols and tetrol; Polyvinyl-based; And bifunctional urethane acrylate. The light-diffusion pressure-sensitive adhesive composition selected from the group consisting of bifunctional urethane acrylates. The method of claim 1, wherein the hydrophobic alkoxysilane compound is tridecyltrimethoxysilane, tridecylmethyldimethoxysilane, undecyltrimethoxysilane, diundecyldimethoxysilane, octadecyldimethylmethoxysilane, octadecyldimethyl Ethoxysilane, decyltrimethoxysilane, hexyltrimethoxysilane, hexylmethyldimethoxysilane, octenyltrimethoxysilane, hexenylmethyldimethoxysilane, phenyltriethoxysilane, benzyltriethoxysilane, phenylethyl Triethoxysilane, quaternary butylpentyldimethylmethoxysilane, bicycloheptenyltriethoxysilane, bicyclicheptanylmethyldimethoxysilane, cyclohexyldimethylethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- 2- (aminoethyl) -3-aminoprop Methyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane and 3- At least one light-diffusion adhesive composition selected from the group consisting of isocyanatepropyltriethoxysilane. The light-diffusion pressure-sensitive adhesive composition of claim 1, wherein the pressure-sensitive adhesive layer made of the light-diffusion pressure-sensitive adhesive composition has a haze value of 30 to 70% and a transmission sharpness of 20 to 120. The light-diffusion pressure-sensitive adhesive composition of claim 1, wherein the pressure-sensitive adhesive layer made of the light-diffusion pressure-sensitive adhesive composition has a polarization degree of 99.94% or more and a luminance decrease of less than 20%. The polarizing plate in which the light-diffusion adhesive layer which consists of a light-diffusion adhesive composition of any one of Claims 1-8 was laminated | stacked. A liquid crystal display device comprising a polarizing plate according to claim 9 on at least one side of a liquid crystal cell.

Images