KR20150143163A

KR20150143163A - Ultra Thin Polarizing Plate and Liquid Crystal Display Device Comprising the Same

Info

Publication number: KR20150143163A
Application number: KR1020140072339A
Authority: KR
Inventors: 최한영; 김대철; 박진영
Original assignee: 동우 화인켐 주식회사
Priority date: 2014-06-13
Filing date: 2014-06-13
Publication date: 2015-12-23

Abstract

The present invention provides an ultrathin polarizing plate and a liquid crystal display device comprising the same. A protection film is attached to one side of a polarizer. An adhesive layer is formed on the other side which is opposite to the one side having the protection film. The adhesive layer includes acrylic copolymer containing a chelating function group and an adhesive composite formed by an ionic antistatic agent. An ultrathin polarizing plate according to the present invention can show superior antistatic characteristic, and also represent superior durability and optical characteristic under severe condition of high temperature and high humidity.

Description

TECHNICAL FIELD [0001] The present invention relates to an ultra-thin polarizing plate and a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-thin polarizing plate and a liquid crystal display device having the same, and more particularly to an ultra-thin polarizing plate capable of exhibiting excellent durability and optical characteristics under severe conditions of high antistatic property and high temperature and high humidity, .

2. Description of the Related Art A liquid crystal display device (LCD) is used for various purposes such as a notebook computer, a mobile phone, a liquid crystal TV, and the like. Generally, a liquid crystal cell including a liquid crystal, a polarizer, .

The polarizing plate used in the liquid crystal display is generally a polyvinyl alcohol (PVA) resin film arranged in a predetermined direction, and a polarizer (or a polarizing plate) having a thickness of about 30 탆 in which an iodine compound or a dichroic polarizing material is adsorbed and oriented, Polarizing film "), and on both sides of the polarizer, first and second polarizer protective films having a thickness of about 80 μm, which are typified by triacetyl cellulose (TAC), are laminated via an adhesive, And a pressure-sensitive adhesive layer to be laminated on the liquid crystal cell is laminated on one side of the polarizer protective film.

Since each constituent film of such a polarizing plate is made of a material having a different molecular structure and composition, it has different physicochemical properties. Polarizers, in which PVA is a stretched film, shrink or swell under high temperature and humidity, so that the constituting films of the polarizing plate are bent or easily fall off, and bubbles are generated.

Especially recently, the market for slim liquid crystal display devices such as a slim large wall-mounted TV, a mobile type computer, a car TV, a display of a car navigation system, and a mobile phone is rapidly expanding. Accordingly, a thin and lightweight ultra thin polarizing plate (UTP) has been required to thin the entire module of a liquid crystal display device.

As a method for producing such an ultra-thin polarizer, a method of thinning the thickness of the polarizer or the polarizer protective film and a method of removing one layer of the polarizer protective film in the configuration of the polarizer have been proposed. However, in the conventional polarizing plate described above, the polarizing plate shrinks or expands under high temperature and humidity, so that the constituent films of the polarizing plate are not durable or lifted from the liquid crystal cell, and the polarizing plate is stretched in the stretching direction There was a problem that it tore easily. In addition, there is a problem that a foreign substance is mixed into an optical member due to a problem of static electricity generated when bonding with a liquid crystal panel, thereby causing defects. Further, the ultra-thin polarizing plate is in direct contact with the iodine-based polarizer and the pressure-sensitive adhesive, so that the iodine-based polarizer and the pressure-sensitive adhesive are in direct contact with each other, there was a concern that the optical characteristics were deteriorated due to bleed-out.

Accordingly, in the production of an ultra-thin polarizing plate, improvement of optical durability as well as durability and antistatic property of a pressure-sensitive adhesive have been urgently required.

Korean Patent No. 2012-0132397

An object of the present invention is to provide an ultra-thin polarizer capable of exhibiting excellent durability and optical characteristics even under severe conditions of high antistatic property and high temperature and high humidity.

Another object of the present invention is to provide a liquid crystal display device having the ultra-thin polarizer on at least one surface of a liquid crystal cell.

On the other hand, according to the present invention, a protective film is attached to one surface of a polarizer, and a pressure sensitive adhesive layer is formed on the other surface of the surface to which the protective film is attached. The pressure sensitive adhesive layer includes an acrylic copolymer containing a chelating functional group and an ionic antistatic agent The present invention provides an ultra-thin polarizing plate formed from the pressure-sensitive adhesive composition.

In one embodiment of the present invention, the acryl-based copolymer containing the chelating functional group can be produced by copolymerization of a (meth) acrylate monomer and a monomer containing an unsaturated double bond and a chelating functional group simultaneously in a molecule.

In one embodiment of the present invention, the chelating functional group is a polyalkylene oxide or a functional group which simultaneously contains a tertiary amine group and an ether group in the molecule.

On the other hand, the present invention provides a liquid crystal display device having the ultra-thin polarizer on at least one side of a liquid crystal cell.

The ultra-thin polarizer formed of the pressure-sensitive adhesive composition comprising the acrylic copolymer containing the chelating functional group and the ionic antistatic agent according to the present invention suppresses the loss of iodine anion in the polarizer and exhibits excellent optical characteristics even under severe conditions of high temperature and high humidity And can exhibit excellent durability and antistatic performance.

Hereinafter, the present invention will be described in more detail.

In one embodiment of the present invention, a protective film is attached to one surface of a polarizer, and a pressure-sensitive adhesive layer is formed on the other surface of the surface to which the protective film is attached, wherein the pressure-sensitive adhesive layer comprises an acrylic copolymer containing a chelating functional group, The present invention relates to an ultra-thin polarizing plate formed from a pressure-sensitive adhesive composition comprising an antistatic agent.

In one embodiment of the present invention, an ultra-thin polarizing plate refers to a direct bonding of a polarizer and a pressure-sensitive adhesive layer without a separate protective film in order to realize a slimmed liquid crystal display.

<Polarizer>

In one embodiment of the present invention, the polarizer is one in which a dichroic dye is adsorbed and oriented on a stretched polyvinyl alcohol-based resin film, and iodine can be used as the dichroic dye.

The polyvinyl alcohol-based resin constituting the polarizer can be obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith.

Other monomers copolymerizable with vinyl acetate include acrylamide monomers having an unsaturated carboxylic acid type, an unsaturated sulfonic acid type, an olefin type, a vinyl ether type, and an ammonium group. The polyvinyl alcohol resin may also be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The degree of polymerization of the polyvinyl alcohol-based resin is usually from 1,000 to 10,000, and preferably from 1,500 to 5,000.

Such a polyvinyl alcohol-based resin film is used as the original film of the polarizer. The method of forming the film of the polyvinyl alcohol-based resin is not particularly limited, and a known method can be used. The thickness of the original film is not particularly limited, and may be, for example, 10 to 150 mu m.

The polarizer is produced by continuously uniaxially stretching a polyvinyl alcohol-based film in an aqueous solution, dyeing with a dichroic dye and adsorbing, treating with an aqueous solution of boric acid, and washing and drying.

The uniaxial stretching of the polyvinyl alcohol film may be performed before dyeing, concurrently with dyeing, or may be performed after dyeing. If uniaxial stretching is carried out after dyeing, it may be carried out before the boric acid treatment, or may be carried out during the boric acid treatment. Of course, it is also possible to perform uniaxial stretching in a plurality of such steps. For uniaxial stretching, other rolls or rolls of different circumferences may be used. The uniaxial stretching may be either dry stretching in air or wet stretching in the state of being swollen with a solvent. The stretching ratio is usually 4 to 8 times.

As a step of dyeing a stretched polyvinyl alcohol film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol film in an aqueous solution containing a dichroic dye can be used. As the dichroic dye, iodine may be used. It is preferable that the polyvinyl alcohol film is pre-immersed in water before dyeing to swell.

In the dyeing step, a method of dying and dyeing a polyvinyl alcohol-based film into an aqueous solution for dyeing usually containing iodine and potassium iodide can be used. Usually, the content of iodine in an aqueous solution for dyeing is 0.01 to 1 part by weight with respect to 100 parts by weight of water (distilled water), and the content of potassium iodide is 0.5 to 20 parts by weight with respect to 100 parts by weight of water. The temperature of the aqueous solution for dyeing is usually 20 to 40 占 폚, and the immersion time (dyeing time) is usually 20 to 1,800 seconds.

The step of treating the dyed polyvinyl alcohol film with boric acid can be carried out by immersing it in an aqueous solution containing boric acid. Normally, the content of boric acid in an aqueous solution containing boric acid is 2 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of water.

When iodine is used as the dichroic dye, it is preferable that the aqueous solution containing boric acid contains potassium iodide, and the content thereof is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of water. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C. The immersing time is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, 200 to 400 seconds.

After the boric acid treatment, the polyvinyl alcohol film is usually washed with water and dried. The washing treatment can be carried out by immersing the boric acid-treated polyvinyl alcohol-based film in water. The temperature of the water during the water treatment is usually 5 to 40 ° C, and the immersion time is usually 1 to 120 seconds.

After washing with water, the polarizer can be obtained. The drying treatment can be usually carried out using a hot air dryer or a far infrared ray heater. The drying treatment temperature is usually 30 to 100 占 폚, preferably 50 to 80 占 폚, and the drying time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

The thickness of the polarizer is not particularly limited, but may be, for example, 5 to 80 탆.

<Protection film>

In one embodiment of the present invention, the protective film is formed only on the other surface of the surface of the polarizer on which the pressure-sensitive adhesive layer is formed, and is not used as a base material when the pressure-sensitive adhesive layer is formed.

The kind of the protective film is not particularly limited as long as it is excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, etc., for example, polyester films such as polyethylene terephthalate, polyethylene isophthalate 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 and acrylonitrile-styrene copolymer; Polyolefin-based films such as polyethylene, polypropylene, cyclo-based or norbornene-structured polyolefin, and ethylene propylene copolymer; Polyimide-based films; Polyethersulfone-based films; A sulphone film, or the like can be used, but the present invention is not limited thereto.

If necessary, a surface treatment layer such as a hard coating layer, an antireflection layer, and an antiglare layer may be further laminated on the protective film.

Specifically, the hard coat layer serves to prevent the surface of the polarizing plate from being damaged, and may be formed of, for example, an acrylic or silicone resin having excellent adhesiveness and hardness.

The antireflection layer serves to prevent reflection of external light on the surface of the polarizing plate, and may be formed by a known method.

Further, the antiglare layer is for preventing the visibility which is caused by external light passing through the surface of the polarizing plate to be prevented. For example, the antiglare layer may be formed by a roughening method such as a sandblast method or an embossing method, And a method in which the mixed composition is applied and cured.

The thickness of the protective film is not particularly limited, but may be 10 to 200 占 퐉, and preferably 10 to 150 占 퐉.

<Pressure-sensitive adhesive layer>

In one embodiment of the present invention, the pressure-sensitive adhesive layer is directly bonded to the polarizer without a separate protective film, so that the polarizer can be made thinner and lighter. Further, the stabilization of the ionic antistatic agent by the acrylic copolymer containing a chelating functional group is used to suppress the bleed-out of the antistatic agent, and even when the polarizer according to the present invention is excellent in the high temperature and high humidity conditions Thermal durability and anti-wet heat optical durability.

Specifically, the KI ion salt used in the polarizer manufacturing process undergoes an ion exchange reaction with the ionic antistatic agent MX contained in the pressure-sensitive adhesive layer under moisture-humidity conditions, so that KI in the polarizer moves to the pressure-sensitive adhesive layer, Is moved to the polarizer layer, which results in a decrease in the concentration of I in the polarizer and a decrease in the polarization of the polarizer due to the decrease in the concentration of I. In order to suppress the lowering of the concentration of I in the polarizer, the antistatic agent in the pressure-sensitive adhesive layer is stabilized by the acrylic copolymer, so that the ion exchange reaction is prevented from progressing, and the decrease in the concentration of I ions in the polarizer can be suppressed.

&Lt; Pressure sensitive adhesive composition &

The pressure-sensitive adhesive composition used in the present invention includes an acrylic copolymer containing a chelating functional group and an ionic antistatic agent.

In one embodiment of the present invention, the chelating functional group may be a polyalkylene oxide or a functional group simultaneously containing a tertiary amine group and an ether group in the molecule.

In one embodiment of the present invention, the monomer which simultaneously contains the unsaturated double bond and the chelating functional group in the molecule may be a (meth) acrylate containing a chelating functional group.

Specifically, as the (meth) acrylate containing a polyalkylene oxide, a compound of the following formula (1) can be used, and as the (meth) acrylate containing a tertiary amine group and an ether group simultaneously in the molecule, To 3 can be used.

[Chemical Formula 1]

In this formula,

R < ₁ _> is hydrogen or a methyl group,

R ₂ is hydrogen, a C ₁ -C ₁₂ alkyl or aryl group, preferably a methyl group,

n is an integer of 0 to 20;

(2)

(3)

In this formula,

R ₃ is hydrogen or a methyl group,

R ₄ to R ₆ are each independently a C ₁ -C ₁₂ alkyl group or an aryl group, preferably a methyl group,

m is an integer of 1 to 10;

As used herein, a C ₁ -C ₁₂ alkyl group means a linear or branched hydrocarbon group having 1 to 12 carbon atoms, and examples thereof include methyl, ethyl, n-propyl, i-propyl, Butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decanyl, n-undecanyl and n-dodecyl.

As used herein, an aryl group includes both an aromatic group and a heteroaromatic group and a partially reduced derivative thereof. The arometric group is a simple or fused ring group of 5 to 15-ary, and the heteroaromatic group means an arometric group containing at least one of oxygen, sulfur or nitrogen. Exemplary aryl groups include, but are not limited to, phenyl, naphthyl, pyridinyl, furanyl, thiophenyl, indolyl, quinolinyl, imidazolinyl, But are not limited to, oxazolyl, thiazolyl, tetrahydronaphthyl, and the like.

The C ₁ -C ₁₂ alkyl and aryl groups may be substituted by one or more of the hydrogen atoms of a C ₁ -C ₆ alkyl group, a C ₂ -C ₆ alkenyl group, a C ₂ -C ₆ alkynyl group, a C ₃ -C ₁₀ A cycloalkyl group, a C ₃ -C ₁₀ heterocycloalkyl group, a C ₃ -C ₁₀ heterocycloalkyloxy group, a C ₁ -C ₆ haloalkyl group, a C ₁ -C ₆ alkoxy group, a C ₁ -C ₆ thio Alkoxy, aryl, acyl, hydroxy, thio, halogen, amino, alkoxycarbonyl, carboxy, carbamoyl, cyano, nitro and the like.

The monomer containing the unsaturated double bond and the chelating functional group at the same time in the molecule is preferably contained in an amount of 1 to 30 parts by weight, more preferably 2 to 10 parts by weight, based on 100 parts by weight of the total monomers used in the production of the acrylic copolymer Do. If the content is less than 1 part by weight, the antistatic property may be improved and the antistatic agent may be prevented from bleeding-out. In contrast, if the content is more than 30 parts by weight, the durability may be deteriorated .

In one embodiment of the present invention, the (meth) acrylate monomer may be a (meth) acrylate monomer having an alkyl group having from 1 to 12 carbon atoms. Specific examples include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) (Meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, pentyl Acrylate, decyl (meth) acrylate, and lauryl (meth) acrylate. Of these, n-butyl acrylate, 2-ethylhexyl acrylate or a mixture thereof is preferable. These may be used alone or in combination of two or more.

The (meth) acrylate monomer is preferably contained in an amount of 80 to 99 parts by weight, more preferably 90 to 95 parts by weight, based on 100 parts by weight of the total monomers used in the production of the acrylic copolymer. When the content is less than 80 parts by weight, the adhesive strength is not sufficient. When the content is more than 99 parts by weight, the cohesive strength may be lowered.

In one embodiment of the present invention, the above-mentioned acrylic copolymer containing a chelating functional group is obtained by copolymerizing a (meth) acrylate monomer, a monomer containing both an unsaturated double bond and a chelating functional group in the molecule at the same time, May be a copolymer of monomers.

The monomer having a crosslinkable functional group is a component for imparting durability and cutability by reinforcing the cohesive strength or adhesion strength of the pressure-sensitive adhesive composition by chemical bonding, and examples thereof include monomers having a hydroxy group, monomers having a carboxyl group, monomers having an amide group, And a monomer having a tertiary amine group. 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. 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.

In addition, the acrylic copolymer according to one embodiment of the present invention may further contain other polymerizable monomers other than the above monomers in a range that does not lower the adhesive force, for example, 10 parts by weight or less, preferably 5 parts by weight or less.

The method for producing the copolymer is not particularly limited and can be produced by a method such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization, which is commonly 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 preferably has a weight average molecular weight (polystyrene conversion, Mw) of 50,000 to 2,000,000, more preferably 400,000 to 2,000,000 as measured by Gel Permeation Chromatography (GPC). If the weight average molecular weight is less than 50,000, cohesion between co-polymers may be insufficient, which may cause problems in adhesion durability. If the weight average molecular weight is more than 2,000,000, a large amount of a diluting solvent may be required to ensure fairness in coating.

In one embodiment of the present invention, as the ionic antistatic agent, for example, an organic cation or an alkali metal cation such as ammonium, phosphonium, or sulfonium can be used as the cation. Specific examples of the organic cations include quaternary ammonium salts substituted with four alkyl groups such as tetrabutylammonium, 1-ethylpyridinium, 1-butylpyridinium, 1-hexylpyridinium, 1-butyl- Butyl-4-methylpyridinium, 1-hexyl-3-methylpyridinium, 1-hexyl-4-methylpyridinium, Pyridinium, pyridinium salts in which the N of the pyridine is substituted with an alkyl group, alkyl groups such as 1-methyl-3-butylimidazolium and 1-methyl-3-hexylimidazolium, Substituted imidazolium salts, quaternary phosphonium salts having four alkyl groups such as tetrabutylphosphonium, and tertiary sulfonium salts having three alkyl groups such as tributylsulfonium. The alkali metal may be lithium, sodium, potassium or cesium, preferably lithium, sodium or potassium. These may be used alone or in combination of two or more.

Anion as OTf ^- (methanesulfonate trifluoroacetate), OTs ^- (toluene-4-sulfonate), OMs ^- ^{(methanesulfonate), Cl -, Br -,} I -, AlCl 4 -, Al 2 Cl 7 - _{^{_{^{, BF 4 -, PF 6 -}}}} , ClO 4 -, NO 3 -, CH 3 COO -, CF 3 COO -, CH 3 SO 3 -, CF 3 SO 3 -, (CF 3 SO 2) 2 N -, ( _{^{CF 3 SO 2) 3 C -}} , AsF 6 -, SbF 6 -, NbF 6 -, TaF 6 -, F (HF) n -, (CN) 2 n -, C 4 F 9 SO 3 -, (C 2 F ₅ SO ₂ ) ₂ N ^- , C ₃ F ₇ COO ^- , (CF ₃ SO ₂ ) (CF ₃ CO) N ^- and the like.

Among them, a sulfonylimide compound is preferable in view of durability and antistatic property, and it may be a compound of the following formula (4).

[Chemical Formula 4]

^{_{M + [(SO 2 R)}} 2 N] -

In this formula,

M is an alkali metal,

R is a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms.

The compound of the formula (4) has a high electronegativity of fluorine atoms of anions and thus has a large effect of stabilizing anions present in nitrogen atoms, thereby improving the hydrophobicity of the antistatic agent and thus being excellent in compatibility with the acrylic copolymer, It is preferable from the standpoint of imparting endurance reliability and physical properties of antistatic property.

The compound of formula 4 is particularly bis (fluoroalkyl sulfonyl) imide potassium _{(KN (FSO 2) 2)} , bis (sulfonyl fluorophenyl) imide sodium _{(NaN (FSO 2) 2)} , bis (alcohol fluorophenyl sulfonyl) imide lithium _{(LiN (FSO 2) 2)} , bis (trifluoromethyl sulfonyl) imide potassium _{(KN (CF 3 SO 2)} 2), methylsulfonyl a bis (trifluoromethanesulfonyl) imide sodium ( _{NaN (CF 3 SO 2) 2} ) or bis (trifluoromethyl sulfonyl) imide lithium _{(LiN (CF 3 SO 2)} 2) , and the like.

The content of the antistatic agent is not particularly limited as long as it is within the range of its function. For example, the content of the antistatic agent may be 0.1 to 3 parts by weight, preferably 0.5 to 1 part by weight, based on 100 parts by weight of the acrylic copolymer. When the above range is satisfied, excellent antistatic properties are exhibited, and the release of iodine ions from the polarizer is effectively suppressed, whereby the optical characteristics and durability of the polarizer can be remarkably improved. If it is contained in an amount of less than 0.1 part by weight, it is difficult to exhibit its effect in a very small amount, and if it exceeds 3 parts by weight, deterioration of adhesion durability due to bleed-out of the antistatic agent from the pressure- This can cause problems.

The pressure-sensitive adhesive composition according to one embodiment of the present invention may further include a crosslinking agent and a silane coupling agent.

In one embodiment of the present invention, the crosslinking agent is a component for reinforcing the cohesive force of the pressure-sensitive adhesive by appropriately 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, naphthalene Diisocyanate compounds such as 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 crosslinking agent is preferably contained in an amount of 0.1 to 15 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the acrylic copolymer based on the solid content. When the content is less than 0.1 parts by weight, the cohesive force becomes small due to insufficient crosslinking, resulting in deterioration of durability and deterioration of cutability. If the content is more than 15 parts by weight, excessive crosslinking reaction may cause a problem of relaxation of residual stress.

In one embodiment of the present invention, the silane coupling agent is added in order to improve the adhesion between the pressure-sensitive adhesive and the substrate. The kind of the silane coupling agent is not particularly limited as long as it is within the range of function, and examples thereof include amino group, epoxy group, An alkoxysilane containing a functional group such as a polyalkylene glycol group, an acrylic group or an alkyl group can be used.

The content of the silane coupling agent is not particularly limited, but is preferably 0.1 to 2.0 parts by weight, more preferably 0.1 to 0.5 parts by weight based on 100 parts by weight of the acrylic copolymer based on the solid content. If the content is less than 0.1 parts by weight, peeling may easily occur under the conditions of wet heat resistance. If the content is more than 2.0 parts by weight, peeling may occur under heat-resistant conditions.

The pressure-sensitive adhesive composition according to one embodiment of the present invention may further contain additives such as a tackifier resin, an antioxidant, a leveling agent, a surface-treating agent, an antioxidant, Lubricants, dyes, pigments, antifoaming agents, fillers, light stabilizers, and the like.

The pressure-sensitive adhesive composition containing the above-described components is applied to the other surface of the surface to which the protective film of the polarizer is bonded to form a pressure-sensitive adhesive layer.

The coating method is not particularly limited as long as it is a method commonly used in the art. For example, the surface of the surface to which the protective film of the polarizer is bonded by a Meyer bar coating method, a gravure coating method, a die coating method, an immersion coating method, And a method of coating on the other surface.

The thickness of the pressure-sensitive adhesive layer formed by the above method is not particularly limited, and may be, for example, 3 to 100 탆, and preferably 10 to 100 탆.

The ultra-thin polarizing plate of the present invention can be applied to all conventional liquid crystal display devices. Specifically, a liquid crystal display device including a liquid crystal panel in which a polarizing plate in which the pressure-sensitive adhesive layers are laminated is bonded to at least one surface of a liquid crystal cell can be constituted.

Therefore, one embodiment of the present invention relates to a liquid crystal display device provided with the ultra-thin polarizing plate on at least one surface of a liquid crystal cell.

Hereinafter, the present invention will be described more specifically with reference to Examples, Comparative Examples and Experimental Examples. It should be apparent to those skilled in the art that these examples, comparative examples and experimental examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Synthesis Example 1: Production of acrylic copolymer containing polyalkylene oxide

86 parts by weight of n-butyl acrylate (BA), 2.0 parts by weight of 2-hydroxyethyl acrylate, 2 parts by weight of acrylic acid, 10 parts by weight of a compound (R ₁ = hydrogen, R ₂ = methyl group, n = 1) and 80 parts by weight of an ethyl acetate solvent were charged. Nitrogen gas was then purged for 1 hour to remove oxygen and then maintained at 62 占 폚. After the mixture was homogenized, 0.07 part by weight of azobisisobutyronitrile (AIBN) as a reaction initiator was added and reacted for 6 hours to prepare an acrylic copolymer having a weight average molecular weight of 1.5 million or more.

Synthesis Example 2: Preparation of an acrylic copolymer containing a tertiary amine group and an ether group

(R ₃ = hydrogen, R ₄ , R ₅ and R ₆ = methyl group, m = 1) instead of the compound of the formula (1) (R ₁ = hydrogen, R ₂ = methyl group, The procedure proceeded as in Synthesis Example 1 to prepare an acrylic copolymer having a weight average molecular weight of 1.5 million or more.

Synthesis Example 3: Production of acrylic copolymer containing polyalkylene oxide

The compounds of formula (I) equal to the (R ₁ = hydrogen, R ₂ = methyl, n = 1) compound of formula (1) in place of (R ₁ = hydrogen, R ₂ = methyl group, n = 10) using, the above Synthesis Example 1 To prepare an acrylic copolymer having a weight average molecular weight of 1.5 million or more.

Synthesis Example 4: Production of acrylic copolymer containing polyalkylene oxide

(R ₁ = hydrogen, R ₂ = methyl group, n = 20) was used in place of the compound of the formula 1 (R ₁ = hydrogen, R ₂ = methyl group, To prepare an acrylic copolymer having a weight average molecular weight of 1.5 million or more.

Synthesis Example 5: Preparation of an acrylic copolymer containing a tertiary amine group and an ether group

Synthesis Example 6: Preparation of an acrylic copolymer containing no chelating functional group

except that 96 parts by weight of n-butyl acrylate (BA) was used instead of 86 parts by weight of n-butyl acrylate (BA), 2.0 parts by weight of 2-hydroxyethyl acrylate, 2 parts by weight of acrylic acid, 2.0 parts by weight of 2-hydroxyethyl acrylate and 2 parts by weight of acrylic acid were proceeded in the same manner as in Synthesis Example 1 to prepare an acrylic copolymer having a weight average molecular weight of 1.5 million or more.

Production Examples 1 to 9: Preparation of pressure-sensitive adhesive composition

The components shown in the following Table 1 were mixed in the following amounts (unit: parts by weight) and diluted with methyl ethyl ketone for coating properties to prepare a pressure-sensitive adhesive composition.

division Acrylic
Copolymer Antistatic agent Cross-linking agent Silane coupling agent Production Example 1 Synthesis Example 1 (100) B1 (1.0) Coronate L (1.0) KBM-403 (0.5) Production Example 2 Synthesis Example 2 (100) B1 (1.0) Coronate L (1.0) KBM-403 (0.5) Production Example 3 Synthesis Example 3 (100) B1 (1.0) Coronate L (1.0) KBM-403 (0.5) Production Example 4 Synthesis Example 4 (100) B1 (1.0) Coronate L (1.0) KBM-403 (0.5) Production Example 5 Synthesis Example 5 (100) B1 (1.0) Coronate L (1.0) KBM-403 (0.5) Production Example 6 Synthesis Example 2 (100) B2 (1.0) Coronate L (1.0) KBM-403 (0.5) Production Example 7 Synthesis Example 2 (100) - Coronate L (1.0) KBM-403 (0.5) Production Example 8 Synthesis Example 6 (100) B1 (1.0) Coronate L (1.0) KBM-403 (0.5) Production Example 9 Synthesis Example 6 (100) B2 (1.0) Coronate L (1.0) KBM-403 (0.5)

Antistatic agent B1: KFSI (bis (fluorosulfonyl) imide potassium)

Antistatic agent B2: 1-hexyl-4-methylpyridinium hexafluorophosphate

Crosslinking agent: Coronate L (COR-L, manufactured by Nippon Polyurethane Industry Co., Ltd.)

Silane coupling agent: KBM-403 (Shin-Etsu)

Example 1: Preparation of ultra-thin polarizer

Example 1-1: Preparation of polarizer

A polyvinyl alcohol resin film having an average degree of polymerization of about 2,400 and a degree of saponification of 99.9 mol% or more and having a thickness of 75 탆 was immersed in pure water at 30 캜 for 2 minutes while stretching it to about 1.5 times. Then, the film was stretched to about 2.0 times while immersing it in a dyeing bath having a weight ratio of iodine / potassium iodide / water of 0.01 / 1.0 / 100 and a temperature of 30 ° C for 3 minutes. Then, it was stretched to about 2.0 times while immersing in an aqueous solution of potassium iodide / boric acid / water mixed at a weight ratio of 10/5/100 at 53 ° C for 1 minute. Then, the film was washed with pure water at 15 DEG C for 1.5 seconds and then dried at 50 DEG C for 5 minutes to prepare a polarizer in which iodine adsorbed orientation was made on polyvinyl alcohol.

Example 1-2: Preparation of composition for forming adhesive layer

3 parts by weight of an acetoacetyl group-modified polyvinyl alcohol resin (Kosenol Z200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 0.3 part by weight of a glyoxal cross-linking agent (SPM-01, manufactured by Nippon Gosei Co., Ltd.) were added to 100 parts by weight of water to prepare an adhesive composition And 50 parts by weight of copper sulfate was added to 100 parts by weight of the adhesive composition to prepare an adhesive layer forming composition.

Example 1-3: Preparation of Polarizing Plate

The adhesive layer-forming composition prepared in Example 1-2 was coated on one surface of the polarizer prepared in Example 1-1 to a dry film thickness of 0.1 mu m, and then a saponified acetylcellulose film (30 cm x 20 cm ). The bonded body was dried at a temperature of 60 캜 for 3 minutes to prepare a polarizing plate.

Example 1-4: Preparation of ultra-thin polarizer plate with adhesive

The pressure-sensitive adhesive composition prepared in Preparation Example 1 was coated on the other surface of the polarizer having the protective film prepared in Example 1-3 so that the thickness after drying was 25 占 퐉 and dried at 100 占 폚 for 1 minute to form a pressure- To prepare an ultra-thin polarizing plate.

Examples 2 to 6: Preparation of ultra-thin polarizer

An ultra-thin polarizing plate was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive compositions of Production Examples 2 to 6 were used instead of the pressure-sensitive adhesive composition of Production Example 1, respectively.

Comparative Examples 1 to 3: Preparation of ultra-thin polarizer

An ultra-thin polarizing plate was produced in the same manner as in Example 1 except that the pressure-sensitive adhesive compositions of Production Examples 7 to 9 were used instead of the pressure-sensitive adhesive composition of Production Example 1, respectively.

Experimental Example 1: Evaluation of thermal durability, antistatic property and anti-wet heat optical durability

The physical properties of the ultra-thin polarizer prepared in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 2 below.

(1) Heat resistance durability evaluation

The pressure sensitive adhesive layer of the ultra-thin polarizing plate was bonded to a Corning glass and subjected to an autoclave treatment, followed by standing at 80 DEG C for 300 hours, and bubbles and peeling phenomena were observed.

◎: No bubbles or peeling at all

○: There are bubbles or peeling, but only in very small areas.

Δ: Bubbles or peeling were confirmed somewhat

X: Bubbles or peeling of 1 cm or more across the area are easily visible to the naked eye.

(2) Evaluation of antistatic property

The surface resistivity of each of the three points of the pressure-sensitive adhesive layer of the ultra-thin polarizing plate was measured ten times by using a surface resistance meter (MCP-HT450, manufactured by Mitsubishi Chemical Co., Ltd.).

⊚: The surface resistivity is less than 1 × ^{10 10}

○: The surface resistivity of less than 5X10 ¹⁰ 1X10 ¹⁰ or more

?: A surface resistivity of not less than 5X10 ¹⁰ and less than 1X10 ¹¹

X: surface resistivity of 1 x ^{10 < 11} >

(3) Wet heat resistance optical durability evaluation

The pressure-sensitive adhesive layer of the ultra-thin polarizing plate was bonded to a Corning glass and subjected to autoclave treatment, and after leaving for 300 hours at 60 DEG C and 90RH%, the degree of polarization was measured.

◎: The degree of polarization exceeds 95%

?: A degree of polarization of 90 to 95%

X: Less than 90% of polarization

division Heat resistance durability Antistatic property Humid heat optical durability Example 1 ◎ ◎ ◎ Example 2 ◎ ◎ ◎ Example 3 ◎ ◎ ◎ Example 4 ◎ ◎ ◎ Example 5 ◎ ◎ ◎ Example 6 ◎ ○ ◎ Comparative Example 1 ◎ X ◎ Comparative Example 2 X △ ○ Comparative Example 3 X △ X

As shown in Table 2 above, the ultra-thin polarizing plates of Examples 1 to 6 formed from the pressure-sensitive adhesive composition comprising the acrylic copolymer containing the chelating functional group and the ionic antistatic agent according to the present invention did not contain an ionic antistatic agent, In comparison with the ultra-thin polarizing plates of Comparative Examples 2 to 3 formed of the pressure-sensitive adhesive composition comprising the ultra-thin polarizing plate of Comparative Example 1 and the acrylic copolymer containing no chelating functional group formed of the pressure-sensitive adhesive composition containing only the acrylic copolymer containing the functional group, Heat resistance and heat durability as well as anti-wet heat optical durability.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Do. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the actual scope of the invention is defined by the appended claims and their equivalents.

Claims

A protective film is attached to one surface of a polarizer, and a pressure-sensitive adhesive layer is formed on the other surface of the surface to which the protective film is attached. The pressure-sensitive adhesive layer includes a pressure-sensitive adhesive composition comprising an acrylic copolymer containing a chelating functional group and an ionic antistatic agent Formed ultra-thin polarizer.

The ultra-thin polarizer according to claim 1, wherein the acryl-based copolymer containing a chelating functional group is prepared by copolymerization of a (meth) acrylate monomer and a monomer containing an unsaturated double bond and a chelating functional group simultaneously in the molecule.

The ultra-thin polarizer according to claim 2, wherein the chelating functional group is a polyalkylene oxide or a functional group simultaneously containing a tertiary amine group and an ether group in the molecule.

The ultra-thin polarizer according to claim 2, wherein the monomer containing the unsaturated double bond and the chelating functional group at the same time in the molecule is a (meth) acrylate containing a chelating functional group.

3. The ultra-thin polarizing plate according to claim 2, wherein the monomer simultaneously containing an unsaturated double bond and a chelating functional group in the molecule comprises at least one selected from compounds represented by the following formulas (1) to (3)
[Chemical Formula 1]

In this formula,
R < ₁ _> is hydrogen or a methyl group,
R ₂ is hydrogen, a C ₁ -C ₁₂ alkyl group or an aryl group,
n is an integer from 0 to 20;
(2)

(3)

In this formula,
R ₃ is hydrogen or a methyl group,
R ₄ to R ₆ are each independently a C ₁ -C ₁₂ alkyl group or an aryl group,
m is an integer of 1 to 10;

The ultra-thin polarizer according to claim 5, wherein R ₂ and R ₄ to R ₆ are methyl groups.

The ultra-thin polarizer according to claim 1, wherein the ionic antistatic agent is a compound represented by the following formula (4):
[Chemical Formula 4]
^{_{M + [(SO 2 R)}} 2 N] -
In this formula,
M is an alkali metal,
R is a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms.

The method according to claim 7, wherein the ionic antistatic agent is bis (fluorosulfonyl) imide potassium (KN (FSO ₂ ) ₂ ), bis (fluorosulfonyl) imide sodium (NaN (FSO ₂ ) ₂ ) (sulfonyl fluorophenyl) (methylsulfonyl trifluoromethanesulfonyl) imide lithium _{(LiN (FSO 2) 2)} , bis imide potassium _{(KN (CF 3 SO 2)} 2), ( methylsulfonyl-trifluoromethyl) bis And at least one selected from the group consisting of imide sodium (NaN (CF ₃ SO ₂ ) ₂ ) and bis (trifluoromethylsulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) ₂ ).

The ultra-thin polarizer according to claim 1, wherein the pressure-sensitive adhesive composition further comprises a crosslinking agent and a silane coupling agent.

9. A liquid crystal display device comprising an ultra-thin polarizing plate according to any one of claims 1 to 9 on at least one surface of a liquid crystal cell.