KR20170046297A - Polarizing Plate and Liquid Crystal Display Device Comprising the Same - Google Patents

Abstract

The present invention provides a polarizing plate sequentially stacking an adhesive layer, a polarizer, a matted protection film, and a prism sheet, and a liquid crystal display device having the same. According to the present invention, the polarizing plate enables the liquid crystal display device to be thin, and enables an image to have excellent visibility compared to that of the existing polarizing plate by improving an optical quality since a moire pattern occurring problem caused by the prism sheet can be solved without using an additional diffusion sheet.

Description

[0001] The present invention relates to a polarizing plate and a liquid crystal display device including the polarizing plate.

The present invention relates to a polarizing plate and a liquid crystal display including the polarizing plate, which can realize excellent visibility when introduced into a liquid crystal display by suppressing occurrence of a moire pattern generated by a prism sheet.

Liquid crystal display devices (LCDs) are used in various fields because they can be manufactured with low power consumption and thinner in a plane, and the market share of flat panel displays is the highest.

A typical liquid crystal display device is composed of a cold cathode tube, a planar light source element using an LED, a liquid crystal panel in which a light diffusion plate, a diffusion sheet, a prism sheet, and a polarizing plate are bonded. In recent years, there has been an increasing demand for thinning of liquid crystal display devices in applications such as large-screen liquid crystal televisions which can be hung on a wall. However, in this case, corresponding to the thinness of liquid crystal display devices, it is necessary to reduce the number of members It becomes.

With respect to such a request, one or a plurality of members are removed by a method in which a prism sheet having a light-condensing property is directly bonded to one surface of a polarizing plate disposed between a liquid crystal cell constituting a liquid crystal panel and a surface light source device, Reduction technique is known.

The prism sheet serves to refract and condense the widely radiated light coming from the diffuser sheet or diffuser plate to increase the brightness. However, due to the combination of the regular sectional shape of the prism sheet and the periodic structure of the liquid crystal cell, a moire fringe having another period is generated. Such a moire pattern causes the display quality such as the visibility of the liquid crystal display device to deteriorate.

Japanese Patent Application Laid-Open No. 2011-123476 discloses a polarizing plate in which a pressure sensitive adhesive exhibiting light diffusing properties is laminated on one side of a polarizing film and a sheet member having a prismatic shape is laminated on the other side. However, such a polarizing plate has a possibility of line contamination or foreign matter incorporation when the light-diffusing pressure-sensitive adhesive is coated, and the effect thereof is also insufficient.

Japanese Laid-Open Patent No. 2011-123476

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a polarizing plate improved in moire pattern generation due to a prism sheet.

Another object of the present invention is to provide a liquid crystal display device including the polarizing plate.

On the other hand, the present invention provides a polarizing plate in which a pressure-sensitive adhesive layer, a polarizer, a matted protective film and a prism sheet are sequentially laminated.

In one embodiment of the present invention, the matted protective film is a film having surface irregularities having a surface roughness (Rz) of 6 to 25 mu m.

The matted protective film may have a haze value of 35 to 80% and a transmittance of 90% or more.

In one embodiment of the present invention, the matted protective film may be bonded to the prism sheet via a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer may be a diffusion pressure-sensitive adhesive layer.

On the other hand, the present invention provides a liquid crystal display device including the polarizer.

The polarizing plate according to the present invention can solve the occurrence of a moire pattern generated from a prism sheet without using a separate diffusion sheet, thereby making it possible to thin a liquid crystal display device and to improve an optical quality thereof so that an image having excellent visibility Can be implemented.

1 is a cross-sectional view schematically showing a polarizing plate according to an embodiment of the present invention.
2 is a schematic view showing a process for producing a matted protective film according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1, a polarizing plate 100 according to an embodiment of the present invention includes a structure in which a pressure sensitive adhesive layer 110, a polarizer 130, a matted protective film 140, and a prism sheet 150 are sequentially laminated . ≪ / RTI > When the polarizing plate 100 is introduced into a liquid crystal display device, the pressure-sensitive adhesive layer 110 is bonded to a liquid crystal cell (not shown).

In an embodiment of the present invention, a protective film 120 may be further provided between the pressure-sensitive adhesive layer 110 and the polarizer 130.

The protective film 110 and the matted protective film 140 may be bonded to the polarizer 120 through an adhesive layer (not shown).

In addition, the matted protective film 140 may be bonded to the prism sheet 150 via an adhesive layer or an adhesive layer (not shown).

In an embodiment of the present invention, the pressure-sensitive adhesive layer or the adhesive layer for bonding the matted protective film 140 and the prism sheet 160 may be a diffusion pressure-sensitive adhesive layer or an adhesive layer, respectively.

The adhesive layer for bonding the matted protective film 140 and the polarizer 120 may also be a diffusion adhesive layer.

The polarizing plate 100 according to an embodiment of the present invention includes a matted protective film 140 to exhibit light diffusibility. The matted protective film 140 serves to alleviate the moiré pattern caused by the regular shape derived from the cross section of the prism sheet and the interference of the regular shape derived from the matrix structure of the color filter of the liquid crystal cell. Specifically, the regularity derived from the surface shape of the prism sheet is relaxed by the diffusion by the matted protective film, so that the interference with the regular shape derived from the matrix structure or the like of the color filter of the liquid crystal cell is greatly alleviated The generation of the moire pattern is suppressed, whereby an image with excellent display quality can be obtained.

In addition to the matted protective film 140, the present invention may further include a pressure sensitive adhesive layer or an adhesive layer for bonding the matted protective film 140 and the prism sheet 160 and the matted protective film 140, And the adhesive layer for bonding the polarizer 120 are formed of a diffusion adhesive layer.

<Protection film>

In one embodiment of the present invention, the protective film 120 is for enhancing the strength and optical properties of the polarizer. The polarizer to be described later is generally made of a hydrophilic resin such as polyvinyl alcohol and is generally vulnerable to moisture. Further, since the polarizer is manufactured through a stretching process, deformation such as shrinkage tends to occur under the humidifying condition, thereby deteriorating the optical characteristics of the polarizing plate. Thus, a protective film made of a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. For example, polyester films such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and polybutylene terephthalate; Cellulose-based films such as diacetylcellulose and triacetylcellulose; Polycarbonate film; Acrylic films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene-based films such as polystyrene, acrylonitrile-styrene copolymer and the like. Further, polyolefin-based films such as polyethylene, polypropylene, cyclo-based or norbornene-structured polyolefins and ethylene propylene copolymers; Vinyl chloride film; Amide type films such as nylon and aromatic polyamide; Imidazole film; Polyethersulfone-based films; Sulfone based films; A polyethyl ketone-based film; Vinyl alcohol film; Polyoxymethylene-based films; And an epoxy-based film. These may be used alone or in combination of two or more. The protective film may be a cured film formed from a thermosetting or photo-curable resin such as acrylic, urethane, acryl-urethane, epoxy, silicone, and the like.

The thickness of the protective film may generally be 1 to 200 占 퐉, preferably 5 to 100 占 퐉 in consideration of workability such as strength, handling and thin film properties.

If necessary, a functional surface treatment layer such as a hard coating layer, an antireflection layer, a diffusion or antiglare coating layer, an antiglare layer, and an antistatic layer may be further laminated on the other surface of the protective film not bonded to the polarizer.

The protective film may be either a protective film or a retardation film serving as a retardation film, or a known retardation film laminated on a protective film.

< Polarizer >

In one embodiment of the present invention, the polarizer 130 is an optical film that serves to convert incident natural light into a desired single polarization state (linearly polarized light state). In general, in the art, It is not limited.

Specifically, the polarizer may be a hydrophilic polymer film such as a polyvinyl alcohol film, a partially-formalized polyvinyl alcohol film, or an ethylene / vinyl acetate copolymer partially saponified film, or a dichromatic film such as iodine or dichromatic dye A film produced by adsorbing a material and uniaxially stretching the film; And polyene oriented films such as dehydrated polyvinyl alcohol films or dechlorinated polyvinyl chloride films. Among them, a polarizer produced by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol-based film and uniaxially stretching the film is particularly preferable in view of high polarization dichroism. The thickness of the polarizer is not particularly limited, but is generally about 5 to 40 mu m.

The polarizer produced by adsorbing iodine on a polyvinyl alcohol film and uniaxially stretching the film is obtained by, for example, immersing a polyvinyl alcohol-based film in an aqueous iodine solution for coloring, and stretching the film to 3 to 7 times Length. &Lt; / RTI &gt; The aqueous solution may contain boric acid, zinc sulfate, zinc chloride or the like as needed, or a polyvinyl alcohol-based film may be immersed in an aqueous solution of potassium iodide or the like. In addition, the polyvinyl alcohol-based film can be immersed and washed in water before coloring, if necessary. The cleaning of the polyvinyl alcohol film not only removes contaminants on the surface of the film or cleans the antiblocking agent, but also swells the polyvinyl alcohol film to prevent nonuniformity such as uneven coloring. The stretching of the film may be carried out after coloring the film with iodine, during the coloring of the film, or before coloring the film with iodine. The stretching may be carried out in an aqueous solution of boric acid or potassium iodide, or in a water bath.

Examples of commercially available polarizers include VF-PS7500, VF-PE6000, VF-PE5000, VF-PE4500, VF-PE3000, VF-PE2000 (Kuraray), M-7500 (Nippon Gosei) .

< Matted  Protective Film>

In one embodiment of the present invention, the matted protective film 140 may be a film having surface irregularities having a surface roughness Rz of 6 to 25 mu m.

In addition, the matted protective film 140 may have a haze value of 35 to 80% and a transmittance of 90% or more. The haze value is a degree of haze that appears when light passes through the sample, which means the ratio of the diffuse transmittance (T _d ) divided by the total transmittance (T _t ). Here, the diffused transmitted light (T _d ) is the amount of scattered light among the light transmitted through the sample, and the total transmitted light (T _t ) is the amount of all light transmitted through the sample. On the other hand, the parallel transmitted light T _p can be expressed by a value obtained by subtracting the diffused transmitted light T _d from the total transmitted light T _t by the amount of transmitted light without scattering among the transmitted light.

The matted protective film 140 can be manufactured using a known method of forming a concavo-convex shape on the surface of the film (Japanese Patent Laid-Open Nos. 2009-196327 and 2009-202382). Specifically, as shown in Fig. 2, the molten transparent resin is extruded from the die into a film, and the extruded film 140a is extruded from a first cooling roll 10 having a flat outer peripheral surface and a first cooling roll 10 having a concave- And sandwiching it between the second cooling rolls 20 to transfer the concave-convex shape of the second cooling roll 20.

Examples of the transparent resin include transparent (meth) acrylic resin, olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, and the like, which are melt-processable resins and are exemplified by polymethyl methacrylate, Acrylonitrile / styrene copolymer resin, polyvinyl chloride resin, polyamide resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate Polyester resins represented by polyethylene terephthalate, polysulfone resins, polyether sulfone resins, polyarylate resins, polyamide resins, and the like.

Specifically, an acrylic thermoplastic resin composition obtained by adding rubber particles to the (meth) acrylic resin may be used as the transparent resin. The content of the rubber particles in the entire acrylic thermoplastic resin composition may be 50% by weight or less. If the content of the rubber particles is larger than 50% by weight, the rigidity of the resin film may be lowered.

As the rubber particles, for example, acrylic rubber particles, butadiene rubber particles, styrene-butadiene rubber particles and the like can be used.

The acrylic thermoplastic resin composition may further contain other components as required, such as an ultraviolet absorber, an organic dye, an inorganic dye, a pigment, an antioxidant, an antistatic agent, a surfactant, and the like.

The first cooling roll 10 may be a rubber roll or a metal elastic roll, and the second cooling roll 20 may be a metal roll.

As the rubber roll, for example, a silicone rubber roll, a fluorine rubber roll, or the like may be used, and sand may be mixed to increase releasability. It is preferable that the hardness of the rubber roll is in the range of A70 占 to A90 占 measured according to JIS K 6253. In order to make the hardness of the rubber roll fall within the above range, it may be arbitrarily performed by adjusting the degree of crosslinking or composition of the rubber constituting the rubber roll.

The metal elastic roll is one in which the inside of the roll is made of rubber or a fluid is injected, and the outer peripheral portion thereof is made of a metal thin film having flexibility. Specifically, in the case where a cylindrical stainless steel thin film having a thickness of 0.2 to 1 mm and made of a silicone rubber roll is coated on the outer peripheral portion of the roll, or a fluid such as water or oil is injected into the inside of the roll , And a cylindrical thin film made of stainless steel having a thickness of about 2 to 5 mm is fixed at the end of the roll and a fluid is sealed inside.

As the metal roll, a metal roll or the like capable of controlling the temperature of the roll surface by passing a fluid, steam, or the like through a roll such as a drilled roll or a spiral roll having a hollow structure, And a metal roll having a desired concavity and convexity formed on its outer circumferential surface by sandblasting, engraving, or the like can be used.

The matted protective film 140 is bonded to the prism sheet with the surface irregularities formed to exhibit light diffusibility.

<Prism Sheet>

In one embodiment of the present invention, the prism sheet 150 is constructed by arranging unit prisms in parallel on one surface of a sheet, thereby intentionally changing the direction of incident light and improving brightness.

Any suitable configuration can be employed for the unit prism within the range in which the effect of the present invention can be obtained. The unit prisms may have a triangular cross section in a cross section parallel to the arrangement direction and parallel to the thickness direction, and may have other shapes (for example, one or both of the triangular slopes have different inclination angles Or a shape having a plurality of flat surfaces). The triangular shape may be a shape that is asymmetric with respect to a straight line orthogonal to the sheet surface beyond the apex of the unit prism (for example, a diagonal triangle) or a shape symmetrical with respect to the straight line (for example, an isosceles triangle). In addition, the apex of the unit prism may be a chamfered curved surface, or a tip end may be cut so as to be a flat surface so as to have a trapezoidal shape. The unit prism may be appropriately selected according to the purpose, but is preferably triangular.

When the unit prism of the prism sheet is in a triangular shape, the apex angle of the unit prism is in the range of 60 to 120 degrees, preferably 85 to 95 degrees, for condensing the light incident on the prism. The height of the unit prism (linear distance along the vertical direction between the bottom surface and the vertex angle of the unit prism) is in the range of 10 to 200 mu m, preferably in the range of 15 to 100 mu m, for ease of handling of the prism sheet. Further, the unit prism pitch interval (the shortest distance between the ridges of adjacent unit prisms) is in the range of 5 to 300 mu m, preferably in the range of 10 to 100 mu m, to fill the above-described apex angle and height.

The unit prisms existing on the surface of the prism sheet may include unit prisms having a plurality of vertex angles, pitch intervals, or heights corresponding to the ranges described above. In addition, the unit prisms of the prism sheet of the present invention may be arranged continuously without gaps or at regular intervals, and the unit prisms may be equally applied to a plurality of unit prisms.

As the material of the prism sheet, various known materials can be used. For example, polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cyclic olefin resins such as polyvinyl chloride resins, polycarbonate resins and norbornene resins, poly Styrene-based copolymer, acrylonitrile-styrene-based copolymer, diacetyl-styrene copolymer, acrylonitrile-styrene copolymer, acrylonitrile-styrene copolymer, Cellulose-based films such as cellulose, triacetylcellulose and the like can be used. Among them, polyolefin resins, acrylic resins, polycarbonate resins, polyester resins, polystyrene resins, methyl methacrylate-styrene copolymers, acrylonitrile-butadiene-styrene Based copolymer, an acrylonitrile-based copolymer, and an acrylonitrile-styrene-based copolymer. If necessary, additives such as an ultraviolet absorber, an antioxidant and a plasticizer may be contained.

The prism sheet can be produced by a known method such as a photopolymer process, a mold extrusion process, a press molding process, an injection molding process, a roll transfer process, a laser ablation process, a mechanical cutting process, and a mechanical grinding process have. Each of these methods may be used alone, or two or more methods may be used in combination.

The thickness of the prism sheet is not particularly limited, but is preferably in the range of 20 to 200 mu m, more preferably in the range of 30 to 100 mu m, for thinning the polarizing plate. The thickness of the prism sheet means the shortest distance from the flat surface (the surface opposite to the surface on which the unit prisms are formed) constituting one surface of the prism sheet to the top of the unit prism.

< The pressure- >

In one embodiment of the present invention, the pressure-sensitive adhesive layer can be formed using a known pressure-sensitive adhesive, and can be formed using, for example, an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a silicone pressure- Among them, an acrylic pressure-sensitive adhesive is preferable from the viewpoints of transparency, adhesive strength, reliability, reworkability and the like.

The acrylic pressure sensitive adhesive composition may include an acrylic copolymer and a crosslinking agent.

The acrylic copolymer may include a (meth) acrylate monomer having an alkyl group of 1-12 carbon atoms and a polymerizable monomer having a crosslinkable functional group.

The (meth) acrylate means acrylate and methacrylate.

Specific examples of the (meth) acrylate monomer having an alkyl group of 1 to 12 carbon atoms include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, (Meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl Acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate and lauryl (meth) acrylate. Of these, n-butyl acrylate, Or a mixture thereof. These may be used alone or in combination of two or more.

The polymerizable monomer having a crosslinkable functional group is a component for imparting durability and breaking property by reinforcing the cohesive strength or adhesive strength of the pressure-sensitive adhesive composition by chemical bonding with the following crosslinking agent, and examples thereof include a monomer having a hydroxy group, Monomers having an amide group, monomers having a tertiary amine group, etc. These monomers may be used alone or in admixture of two or more.

Examples of the monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl Hydroxypropyleneglycol (meth) acrylate, hydroxyalkylene glycol having 2 to 4 carbon atoms in the alkylene group (e.g., methoxyethyl (meth) acrylate, Hydroxybutyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxynonyl (meth) acrylate, 4-hydroxybutyl vinyl ether, Vinyl ether, and 10-hydroxydecyl vinyl ether. Of these, 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl vinyl ether is preferable.

Examples of the monomer having a carboxyl group include monovalent acids such as (meth) acrylic acid and crotonic acid; Dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid, and monoalkyl esters thereof; 3- (meth) acryloylpropionic acid; A succinic anhydride ring-opening addition adduct of 2-hydroxyalkyl (meth) acrylate in which the alkyl group has 2 to 4 carbon atoms, anhydrous succinic ring opening adduct of a hydroxyalkylene glycol (meth) acrylate having 2 to 4 carbon atoms in the alkylene group , And compounds obtained by ring-opening addition of succinic anhydride to a caprolactone adduct of 2-hydroxyalkyl (meth) acrylate in which the alkyl group has 2-3 carbon atoms. Of these, (meth) acrylic acid is preferable.

Examples of the monomer having an amide group include (meth) acrylamide, N-isopropyl acrylamide, N-tertiary butyl acrylamide, 3-hydroxypropyl (meth) acrylamide, 4-hydroxybutyl (Meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide and 2-hydroxyethylhexyl (meth) acrylamide. Of these, (meth) acrylamide is preferable.

Examples of the monomer having a tertiary amine group include N, N- (dimethylamino) ethyl (meth) acrylate, N, N- (diethylamino) ethyl (meth) ) Acrylate, and the like.

The polymerizable monomer having a crosslinkable functional group is preferably contained in an amount of 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, based on 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms. When the content is less than 0.05 part by weight, the cohesive force of the pressure-sensitive adhesive becomes small and durability may be deteriorated. When the content is more than 10 parts by weight, a high gel fraction may lower the adhesive strength and cause durability problems.

The acrylic copolymer may further contain other polymerizable monomers other than the monomers in an amount not lowering the adhesive strength, for example, 10% by weight or less based on the total amount.

The method for producing the acrylic copolymer is not particularly limited, and it can be produced by methods such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization which are generally used in the art, and solution polymerization is preferable. In addition, a solvent, a polymerization initiator, a chain transfer agent for molecular weight control and the like which are usually used in polymerization can be used.

The acrylic copolymer generally has a weight average molecular weight (in terms of polystyrene) measured by Gel Permeation Chromatography (GPC) of usually 50,000 to 2,000,000, preferably 1,000,000 to 2,000,000.

The crosslinking agent is a component for reinforcing the cohesive force of the pressure-sensitive adhesive by properly crosslinking the copolymer, and the kind thereof is not particularly limited. Examples thereof include isocyanate compounds and epoxy compounds, which may be used alone or in combination of two or more.

Examples of the isocyanate compound include tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate , Diisocyanate compounds such as naphthalene diisocyanate; An adduct obtained by reacting 3 moles of a diisocyanate compound with 1 mole of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate compound in which 3 moles of a diisocyanate compound is self-condensed, a diisocyanate obtained from 2 moles of 3 moles of a diisocyanate compound And multifunctional isocyanate compounds containing three functional groups such as burette, triphenylmethane triisocyanate and methylene bistriisocyanate in which the remaining one mole of diisocyanate is condensed in urea.

Examples of the epoxy compound include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol Hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, glycerol diglycidyl ether, glycerol diglycidyl ether, Diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcinol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, trimethylol propane triglycidyl ether, pentaerythritol Polyglycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanurate N, N ', N'-tetraglycidyl-m-glycidoxyethyl isocyanurate, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, Xylylenediamine, and the like.

In addition, an isocyanate compound, an epoxy compound, and a melamine compound may be used alone or in admixture of two or more.

Examples of the melamine-based compound include hexamethylol melamine, hexamethoxymethyl melamine, and hexabutoxymethyl melamine.

The amount of the crosslinking agent is preferably 0.1 to 5 parts by weight, more preferably 0.1 to 2 parts by weight based on 100 parts by weight of the acrylic copolymer. If the content is less than 0.1 part by weight, the cohesive force becomes small due to insufficient crosslinking, resulting in deterioration of durability such as peeling and deterioration of cutability. If the content is more than 5 parts by weight, excessive crosslinking reaction may cause problems in relaxation of residual stress have.

The pressure-sensitive adhesive composition may further include a silane coupling agent.

The type of the silane coupling agent is not particularly limited, and examples thereof include vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- Glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethylethoxysilane, 3-glycidoxypropyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3- Methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxy Silane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) Propylmethyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane Silane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanate propyltriethoxysilane, and the like. These may be used alone or in combination of two or more.

The amount of the silane coupling agent is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the acrylic copolymer. When the content is less than 0.01 part by weight, the amount is too small and durability is not expected to be improved. If the content is more than 5 parts by weight, the cohesive strength is excessively increased.

The pressure-sensitive adhesive composition may further contain additives such as a tackifier resin, an antioxidant, a corrosion inhibitor, a leveling agent, a surface-treating agent, a surface-treating agent, Lubricants, dyes, pigments, antifoaming agents, fillers, light stabilizers, antistatic agents, and the like.

In one embodiment of the present invention, the thickness of the pressure-sensitive adhesive layer may be adjusted according to the adhesive force, and may be usually 5 to 50 占 퐉, preferably 20 to 35 占 퐉.

In an embodiment of the present invention, the pressure sensitive adhesive layer for bonding the matted protective film 140 and the prism sheet 150 may be a diffusion pressure sensitive adhesive layer.

The diffusion pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer in which particles capable of scattering and diffusing light are dispersed. Various materials such as organic particles and inorganic particles can be used as long as the particles are mixed and dispersed in the pressure-sensitive adhesive resin so as to exhibit uniform and high light diffusibility, and are not particularly limited in the present invention.

For example, the organic particles may be particles composed of a polystyrene type resin, a polyolefin type resin such as polyethylene or polypropylene, or a polymer compound such as acrylic resin. Further, it may be a particle composed of a copolymer formed by copolymerization of two or more kinds of monomers selected from ethylene, propylene, styrene, methyl methacrylate, benzoguanamine, formaldehyde, melamine, butadiene and the like. Examples of the inorganic particles include particles of silica, calcium carbonate, aluminum hydroxide, titanium dioxide and the like.

These particles are preferably colorless or white.

In addition, the shape of the particles may be various shapes, and is not particularly limited in the present invention. Preferably, spheres are suitable. The average particle diameter of the particles is in the range of 0.1 to 10 mu m, and is preferably in the range of 0.5 to 5 mu m. If the average particle diameter of the particles is less than the above-mentioned range, the light diffusion function is not exhibited. On the contrary, if the average particle diameter of the particles exceeds the above-mentioned range, the display quality can be lowered when applied to a liquid crystal display device.

The content of such particles is not particularly limited and can be adjusted according to the average particle diameter of the particles and the thickness of the diffusion adhesive layer. For example, it may be 1 to 50 parts by weight based on 100 parts by weight of the pressure-sensitive adhesive.

In addition, since the particles are in powder form, the dispersion stability is lowered when they are directly added to the pressure-sensitive adhesive resin, and the particles are not uniformly distributed in the pressure-sensitive adhesive resin. Therefore, it is preferable that the particles are completely dispersed in a solvent and then added to the pressure-sensitive adhesive. The solvent for dispersing the particles is not particularly limited. For example, the same solvent as the solvent used in the production of the pressure-sensitive adhesive may be used. Acetate-based and benzene-based solvents having excellent dispersibility and solvent resistance to organic particles Or ketone-based solvents such as ethyl acetate, toluene, xylene, methyl ethyl ketone and the like.

In one embodiment of the present invention, the diffusion pressure sensitive adhesive layer may have a haze value ranging from 10 to 40%. If the haze value of the diffusion adhesive layer is less than the above range, the light diffusion may be lowered and a moiré pattern may be generated. If the haze value is larger than the above range, the scattering angle may become larger and the luminance may be lowered.

< Adhesive layer >

In one embodiment of the present invention, the adhesive layer may be formed using a known adhesive. As the adhesive, a material excellent in transparency, thermal stability, low birefringence and the like is preferable. Specific examples include water-based adhesives, thermoplastic adhesives, hot-melt adhesives, rubber adhesives, thermosetting adhesives, photocurable adhesives, inorganic adhesives, and natural adhesives. Examples of the water-based adhesive include an ion exchange water, an adhesive containing Z200 (Nippon Gosei) and sodium glyoxylate, an ion exchange water, an adhesive containing PVA (Kuraray KL-318), glyoxylic acid and zinc chloride, Adhesives including PVA (Kuraray KL-318) and Sumirejin 650 (30% solids) may be used, and KR-70T (Adeka) may be used as the photo-curing adhesive.

The thickness of the adhesive layer can be appropriately determined depending on the kind of the resin serving as the adhesive, the adhesive strength, the environment in which the adhesive is used, and the like. The thickness of the adhesive layer may be in the range of tens to hundreds of nm in the case of an aqueous adhesive, and in the range of 0.5 to 20 μm, preferably in the range of 1 to 10 μm in the case of a photocurable adhesive.

An adhesive layer for bonding the matted protective film 140 and the polarizer 120 and / or an adhesive layer for bonding the matted protective film 140 and the prism sheet 160 The adhesive layer may be a diffusion adhesive layer.

The diffusion adhesive layer is an adhesive layer in which particles capable of scattering and diffusing light are dispersed. As long as the particles are mixed and dispersed in the adhesive resin so as to exhibit uniform and high light diffusing properties, various materials such as organic particles and inorganic particles can be used, and the present invention is not particularly limited.

Specifically, the material, shape, content and the like of the light-diffusing particles are the same as those described above in connection with the diffusion pressure-sensitive adhesive layer.

The adhesive used for forming the diffusion adhesive layer is not particularly limited as long as it has excellent adhesion and optical transparency and does not change with time, but a photo-curable adhesive can be used.

The photo-curing adhesive is crosslinked and cured by receiving an active energy ray such as ultraviolet (UV), electron beam (EB) and the like and exhibits a strong adhesive force. The photo-curable adhesive may be composed of a reactive oligomer, a reactive monomer, and a photopolymerization initiator.

The reactive oligomer is an important component for determining the characteristics of the adhesive, and forms a cured film by forming a polymer bond by a photopolymerization reaction. Examples of the reactive oligomer that can be used include a polyester resin, a polyether resin, a polyurethane resin, an epoxy resin, a polyacrylic resin, and a silicone resin.

The reactive monomer serves as a crosslinking agent and a diluent for the reactive oligomer described above, and affects the adhesion property. Examples of the reactive monomer that can be used include monofunctional monomers, polyfunctional monomers, epoxy-based monomers, vinyl ethers, and cyclic ethers.

The photopolymerization initiator absorbs light energy to generate radicals or cations to initiate photopolymerization, and a photopolymerization initiator suitable for the photopolymerization resin is selected and used. Examples of the photo radical polymerization initiator include benzoin ethers, amines, acetophenones, thioxanthones and benzophenones. Examples of photo cationic polymerization initiators include diazonium salts, iodonium salts, sulfo And metal nonsen compounds.

A photo-sensitizer, a thickener, a polymerization inhibitor and the like may be used as additives in the above-mentioned composition according to the use.

In one embodiment of the present invention, the diffusion adhesive layer may have a haze value in the range of 10 to 40%.

When the haze value of the diffusion adhesive layer is less than the above range, the light diffusion may be lowered and a moiré pattern may be generated. If the diffusion adhesive layer is out of the above range, the scattering angle may become larger and the luminance may be lowered.

When a polarizing plate according to an embodiment of the present invention is applied to the upper, lower or upper and lower portions of a liquid crystal cell, a protective film, a diffusion adhesive layer, and / or a diffusion adhesive layer, Polarizers are not located between the polarizers of the lower polarizer but located outside of the polarizers, so that the light emitted from the backlight unit is prevented from being polarized-diffused-polarized, thereby reducing polarization and brightness.

One embodiment of the present invention relates to a liquid crystal display device including the polarizing plate.

The type of the liquid crystal cell included in the liquid crystal display device is not particularly limited and may be, for example, a manual mode such as TN (twisted nematic) type, STN (super twisted nematic) type, F (ferroelectic) A matrix type liquid crystal cell; An active matrix type liquid crystal cell such as a two terminal type or a three terminal type; And may be applied to both in-plane switching (IPS) and vertical alignment (VA) liquid crystal cells.

The types of the other constituent elements constituting the liquid crystal display device, for example, the types of the upper and lower substrates (e.g., color filter substrate or array substrate) are not particularly limited, and configurations known in this field can be employed without limitation .

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are for illustrative purpose only and that the scope of the present invention is not limited thereto.

Reference Example  1: Preparation of acrylic rubber particles

As the acrylic rubber particles, acrylic rubber particles having a three-layer structure obtained by the following production method were used.

First, 1700 g of ion-exchanged water, 0.7 g of sodium carbonate and 0.3 g of sodium persulfate were poured into a glass reaction vessel having an inner volume of 5 L, stirred under a nitrogen stream, and then pellet OT-P (manufactured by Kao Corporation) 4.46 g, ion exchanged water 150 g, methyl methacrylate 150 g, and allyl methacrylate 0.3 g were charged, and then the temperature was raised to 75 캜 and stirring was continued for 150 minutes.

Subsequently, a mixture of 689 g of butyl acrylate, 162 g of styrene, 17 g of allyl methacrylate, 0.85 g of sodium persulfate, 7.4 g of Pelex OT-P and 50 g of ion-exchanged water was passed through a separate inlet for 90 minutes And the polymerization was further continued for 90 minutes.

After completion of the polymerization, 30 g of ion-exchanged water in which a mixture of 326 g of methyl acrylate and 14 g of ethyl acrylate and 0.34 g of sodium persulfate was dissolved was added from another inlet over 30 minutes.

After the addition was completed, the polymerization was further maintained for 60 minutes. The resulting latex was added to a 0.5% aqueous solution of aluminum chloride to coagulate the polymer. This was washed five times with hot water at about 50 DEG C and then dried to obtain acrylic rubber particles having a three-layer structure.

Reference Example  2: Preparation of diffusion adhesive

A four-neck jacket reactor (1L) was equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel and a nitrogen gas introducing tube. The reactor was charged with nitrogen gas, 70 parts by weight of epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, 20 parts by weight of neopentyl glycol diglycidyl ether, 10 parts by weight of 2-ethylhexyl glycidyl ether, 10 parts by weight of triarylsulfonium hexa 2.25 parts by weight of fluorophosphate and 500 parts by weight of a propylene carbonate solution were mixed and defoamed to prepare a photo-curable adhesive solution.

A solution prepared by dispersing 2 parts by weight of polymethylmethacrylate particles (average particle size: 5 mu m, spherical) in toluene solvent was added to 100 parts by weight of the photocurable adhesive resin thus prepared, diluted with toluene to a concentration of 20% .

Manufacturing example  One: Matted  Production of protective film

A matted protective film was produced by using the extrusion apparatus of the following constitution according to the method described in the embodiments of Japanese Patent Laid-open Nos. 2009-196327 and 2009-202382.

Extruder: screw diameter 110 mm, single screw extruder (Toshiba Machinery Co., Ltd.)

Die: T die

First cooling roll: Silicone rubber roll having an outer diameter of 450 mm and a hardness of 70

Second cooling roll: A stainless steel metal roll (drilled roll) having an outer diameter of 450 mm and a concavo-convex shape with a surface roughness (Rz) of 8.2 mu m formed by sandblasting,

70% by weight of a methacrylic resin having a thermal deformation temperature (Th) of 100 占 폚, obtained by copolymerization of a monomer component comprising 96% by weight of methyl methacrylate and 4% by weight of methyl acrylate, 30% by weight was melt-kneaded using an extruding apparatus having the above-described configuration, extruded from the die into a film, and transferred to a matted protective film having a surface roughness (Rz) of 6.7 탆 .

Manufacturing example  2: Matted  Production of protective film

A matted protective film was produced in the same manner as in Production Example 1, except that a stainless steel-made metal roll having a concavo-convex shape having a surface roughness (Rz) of 13.5 占 퐉 was formed as a second cooling roll.

Manufacturing example  3: Matted  Production of protective film

A matted protective film was produced in the same manner as in Production Example 1, except that a stainless steel-made metal roll having a concavo-convex shape of 22.5 占 퐉 in surface roughness (Rz) was used as the second cooling roll.

Manufacturing example  4: Matted  Production of protective film

A matted protective film was produced in the same manner as in Production Example 1, except that a stainless steel-made metal roll having a concavo-convex shape having a surface roughness (Rz) of 26.0 占 퐉 was used as the second cooling roll.

The surface roughness (Rz) of the matted protective films obtained in Production Examples 1 to 4 was measured with an SJ-400 instrument (boram trade) in accordance with JIS B0601-2001, and the total light transmittance (Tt) and haze ) Were measured with HM-150 (Murakami) according to JIS K7136 and JIS K7105, respectively, and are shown in Table 1 below.

Manufacturing example Rz (μm) Tt (%) Haze (%) One 6.7 91.6 35.8 2 9.7 91.5 58.6 3 17.4 91.7 78.2 4 21.1 91.8 79.1

Example  1-3: Preparation of Polarizer

1, on one side of a polyvinyl alcohol polarizer (18 占 퐉 thick) 130 in which iodine was adsorbed and aligned, as shown in the following Table 2, the matted protective film obtained in the above Production Examples 1 to 3 (Thickness 80 占 퐉) 150 is bonded to the matted protective film 140 using the pressure-sensitive adhesive described in Table 2 below, and then the other polarizer 130 is bonded to the other A polarizing plate 100 was prepared by bonding a triacetylcellulose protective film 120 having a thickness of 40 탆 to the surface of the protective film 120 and forming a pressure sensitive adhesive layer 110 on the protective film 120.

Example  4: Preparation of polarizing plate

A polarizing plate was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive was not used for bonding the matted protective film 140 obtained in Production Example 4 and the prism sheet (thickness 80 μm) Respectively.

Example  5: Preparation of polarizer

A polarizing plate was produced in the same manner as in Example 1, except that the adhesive described in Table 2 was used to bond the matted protective film 140 and the prism sheet (thickness 80 탆) 150.

Comparative Example  1-3: Preparation of Polarizer

A polarizing plate was produced in the same manner as in Examples 1 to 3 except that a general protective film was used in place of the matted protective film, as shown in Table 2 below.

Protective film adhesive Example 1 Production Example 1 Diffusion PSA-1 Example 2 Production Example 2 Diffusion PSA-2 Example 3 Production Example 3 PSA Example 4 Production Example 4 unused Example 5 Production Example 1 Diffusion adhesive Comparative Example 1 PF-1 Diffusion PSA-1 Comparative Example 2 PF-1 Diffusion PSA-2 Comparative Example 3 PF-1 PSA

Diffusion PSA-1: Acrylic spreading adhesive (LINTEC) having a thickness of 25 μm and a haze value of 33%

Diffusion PSA-2: Acrylic spreading pressure-sensitive adhesive (LINTEC) having a thickness of 25 μm and a haze value of 20%

PSA: a non-diffusible acrylic adhesive having a thickness of 25 μm and a haze value of 5.0% or less

PF-1: 60 占 퐉 thick; acrylic resin film (Technoroy S001, Sumitomo Chemical)

Diffusion Adhesive: A photocurable adhesive having a haze value of 30% obtained in Reference Example 2

Experimental Example  One:

The properties of the polarizing plates prepared in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 3 below.

(1) moire pattern

The prepared polarizing plate is bonded to the lower polarizing plate of the liquid crystal cell and the upper polarizing plate of the liquid crystal cell is joined with a conventional polarizing plate not including the matted protective film and then the reflecting plate, And laminated on a prism sheet of a backlight unit stacked as shown in Fig. Then, the generation intensity of the moire pattern caused by the prism sheet was visually observed and evaluated based on the following criteria.

<Standard>

◎: Moire pattern does not occur at all

○: Moire pattern slightly occurred

△: moire pattern partially occurs

X: The moire pattern appears clearly

(2) LED Noh

The prepared polarizing plate is bonded to the lower polarizing plate of the liquid crystal cell, and the upper polarizing plate of the liquid crystal cell is joined with a conventional polarizing plate not including the matted protective film, and then a reflection plate, a light source (LED) Were laminated on the prism sheet of the backlight unit stacked in this order. Subsequently, the upper polarizer was turned to the viewer side to visually observe whether the LED lamp was visually observed and evaluated based on the following criteria.

LED no. Refers to a phenomenon in which a dot (DOT) type of light source (LED) used in a direct mode panel looks stained when driven in a dark room.

<Standard>

○: No LED is visible

X: LED lamp is visible

Moire pattern LED Mura Example 1 ◎ ○ Example 2 ◎ ○ Example 3 ◎ ○ Example 4 ◎ ○ Example 5 ◎ ○ Comparative Example 1 △ × Comparative Example 2 △ × Comparative Example 3 × ×

As shown in Table 3, the polarizing plates of Examples 1 to 5 including the matted protective film were compared with the polarizing plates of Comparative Examples 1 to 3 which did not include the matted protective film, Which is an improvement over the previous year.

100: polarizer
110: pressure-sensitive adhesive layer 120: protective film
130: Polarizer 140: Matted protective film
150: prism sheet

Claims (15)

A pressure-sensitive adhesive layer, a polarizer, a matted protective film, and a prism sheet are sequentially laminated. The polarizing plate according to claim 1, wherein the matted protective film has a surface roughness (Rz) of 6 to 25 탆. The polarizing plate according to claim 1, wherein the matted protective film has a haze value of 35 to 80% and a transmittance of 90% or more. The polarizing plate according to claim 2, wherein the matted protective film has surface unevenness formed surfaces thereof bonded to a prism sheet to exhibit light diffusibility. The polarizer of claim 1, further comprising a protective film between the pressure-sensitive adhesive layer and the polarizer. The polarizing plate according to claim 1, wherein the matted protective film is bonded to the prism sheet via a pressure-sensitive adhesive layer. The polarizing plate according to claim 6, wherein the pressure-sensitive adhesive layer is a diffusion pressure-sensitive adhesive layer. The polarizing plate according to claim 7, wherein the diffusion adhesive layer has a haze value in the range of 10 to 40%. The polarizing plate according to claim 1, wherein the matted protective film is bonded to the prism sheet via an adhesive layer. The polarizing plate according to claim 9, wherein the adhesive layer is a diffusion adhesive layer. The polarizing plate according to claim 10, wherein the diffusion adhesive layer has a haze value in the range of 10 to 40%. The polarizer according to claim 1, wherein the matted protective film is bonded to the polarizer via an adhesive layer. The polarizing plate according to claim 12, wherein the adhesive layer is a diffusion adhesive layer. 14. The polarizing plate according to claim 13, wherein the diffusion adhesive layer has a haze value in the range of 10 to 40%.  A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 14.

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