WO2013027980A2 - Polarizing plate - Google Patents

Abstract

The present invention relates to a polarizing plate and a liquid crystal display. One illustrative example of a polarizing plate is lighter and thinner than a conventional polarizing plate, and has superior durability, water resistance, usability, and ability to suppress the leakage of light. Additionally, the illustrative polarizing plate prevents the problem in which a curl develops on the polarizing plate or a polarizer during a manufacturing process, and exhibits excellent resistance to heat and thermal shock.

Description

Polarizer

The present invention relates to a polarizing plate and a liquid crystal display device.

A polarizing plate is an optical functional film applied to apparatuses, such as a liquid crystal display (LCD) etc., for example.

The polarizing plate includes a polarizer which is a functional sheet capable of extracting only light vibrating in one direction from light incident while vibrating in various directions, and may further include a protective film which is usually attached to both surfaces of the polarizer. In addition, the polarizing plate may further include a pressure-sensitive adhesive layer formed under the protective film and used to adhere the liquid crystal panel and the polarizing plate, and a release film formed under the pressure-sensitive adhesive layer. In addition, the polarizing plate may include an additional functional film such as an antireflection film or a retardation film.

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

One exemplary polarizer of the present invention is a polarizer disposed sequentially; Active energy ray-curable adhesive layer; And a pressure-sensitive adhesive layer of a single layer, wherein the pressure-sensitive adhesive layer has a first surface and a second surface, and the peeling force on the alkali free glass is different from each other.

In this specification, when two or more elements are arranged in sequence, for example, "A and B" arranged in the term sequence, the elements A and B are arranged in the above order, but between A and B When another element is interposed, the case where A, C, and B are arrange | positioned in the said order is included, for example.

In addition, in this specification, that two elements are attached or directly attached to each other, for example, that "B is directly attached to A", does not include another element on at least one major surface of A. , B may be directly attached.

The exemplary polarizing plate includes a polarizer, an adhesive layer and an adhesive layer sequentially disposed. In another example of the polarizing plate, the adhesive layer may be directly attached to the polarizer, and the adhesive layer may be directly attached to the adhesive layer. 1 shows a structure 1 of an exemplary polarizing plate, in which the polarizer 11, the adhesive layer 12, and the pressure-sensitive adhesive layer 13 are sequentially arranged.

Since the polarizer is usually made of a hydrophilic resin such as polyvinyl alcohol or the like, the polarizer generally exhibits properties vulnerable to moisture. In addition, when the polarizer is manufactured, it is common to go through an stretching step, and thus, under humidification conditions, shrinkage and the like are likely to occur, thereby deteriorating optical characteristics of the polarizer. Therefore, in general, in order to reinforce the properties of the polarizer, it is common to attach a protective film represented by a TAC (Triacetylcellulose) film or the like on both sides of the polarizer, and if there is no protective film, durability due to weak dimensional stability of the polarizer And optical properties are greatly reduced, there is a problem that the water resistance is also significantly weak.

To this end, in one exemplary structure of the polarizing plate of the present invention, at least one major surface of the polarizer does not adhere to the protective film, thereby realizing a thinner and lighter structure, while at the same time the main surface of the polarizer to which the protective film is not attached. The structure which continuously adheres an adhesive bond layer and an adhesive layer directly is employ | adopted. In addition, the exemplary polarizing plate of the present invention can solve the above problems due to the weak dimensional stability of the polarizer by showing different peeling forces on both major surfaces of the pressure-sensitive adhesive layer. In the present specification, as described above, the polarizing plate in which the protective film is omitted from at least one surface of the polarizer may be referred to as a thin polarizer.

The polarizer is not particularly limited, and those commonly used in the art may be used. As a polarizer, a polyvinyl alcohol-type polarizer etc. can be used, for example. Such a polarizer may have a form in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. Polyvinyl alcohol-type resin which comprises a polarizer can be obtained by gelatinizing polyvinylacetate resin, for example. As polyvinyl acetate resin, Homopolymer of vinyl acetate; And copolymers of vinyl acetate and other monomers copolymerizable with the above. Examples of the monomer copolymerizable with vinyl acetate include, but are not limited to, a mixture of one or more kinds of unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The degree of gelation of the polyvinyl alcohol resin is usually 85 mol% to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used.

An active energy ray curable adhesive layer is disposed on one side of the polarizer. When the polarizing plate is a thin polarizing plate, the adhesive layer may play a major role in securing physical properties of the polarizing plate. For example, the pressure-sensitive adhesive layer has a first surface and a second surface, in one example, the first surface exhibits a higher tensile modulus than the second surface, and the first surface adheres to the adhesive layer. It may become. In this case, the first surface exhibits a lower peel force than the second surface, so that it can be easily peeled off from the polarizer. However, in the present invention, the adhesive is disposed between the polarizer and the adhesive, and cured after the reactive substance in the form of a single molecule of the adhesive penetrates or diffuses into the adhesive before the adhesive layer is cured, and the adhesive is the adhesive layer. It is possible not only to swell the first surface of or to increase the roughness of the surface, thereby ensuring adhesion between the pressure-sensitive adhesive layer and the polarizer, thereby providing a polarizing plate having excellent physical properties. In addition, an active energy ray-curable adhesive may be used instead of the water-based adhesive to prevent curling of the polarizer due to deformation of the polarizer and the protective film due to heat during the heat drying and the heat curing of the water-based adhesive in the manufacturing process of the polarizing plate. In addition, the protection of the polarizer can be effectively performed to prevent the occurrence of cracking of the polarizer even under heat or thermal shock conditions.

As used herein, the term “curing the adhesive composition or the pressure-sensitive adhesive composition” refers to a process of changing the adhesive composition or the pressure-sensitive adhesive composition to express the adhesive or adhesive properties by physical action or chemical reaction of the components of the composition. In addition, the term "active energy ray" in the present specification, microwaves, infrared (IR), ultraviolet (UV), X-rays and γ-rays, as well as α particle beam (proton beam) It may mean a particle beam, such as a neutron beam (electron beam) and an electron beam (electron beam), and may be an ultraviolet ray or an electron beam or the like. In addition, the "active energy ray hardening type" may mean that hardening as described above may be induced by irradiation of active energy rays. In one example, the curing of the adhesive composition may be performed through free radical polymerization or cationic reaction by irradiation of active energy rays, and preferably, free radical polymerization and cationic reaction may be performed simultaneously or sequentially together. have.

The adhesive layer may include a composition containing an epoxy compound or an acrylic monomer in a cured state, and preferably may include a composition containing an epoxy compound and an acrylic monomer in a cured state.

For example, the adhesive composition is 5 to 80 parts by weight of the epoxy compound and 10 to 200 parts by weight of the acrylic monomer, preferably 15 to 60 parts by weight of the epoxy compound and 20 to 150 parts by weight of the acrylic monomer. It may include wealth. When the epoxy compound and the acrylic monomer are included in the above content range, curing of the adhesive composition may be induced more effectively, and curing may be caused due to the living property of the cationic reaction that may cause a dark reaction even after irradiation of active energy rays. By proceeding more efficiently, physical properties can be improved. In the present specification, the unit "parts by weight" means a ratio of the weight between each component. By adjusting the ratio of the components of the adhesive composition as described above, it is possible to provide an adhesive composition excellent in curing efficiency and physical properties after curing.

As used herein, the term "epoxy compound" may mean a monomeric, oligomeric or polymeric compound comprising one or more, preferably two or more epoxy groups.

An epoxy compound can improve physical properties, such as water resistance and adhesive force of an adhesive bond layer.

As said epoxy compound, what can be bridge | crosslinked or superposed | polymerized by a cation reaction can be used, for example.

In one example, as the epoxy compound, an epoxy resin having a weight average molecular weight (Mw) of 1000 to 5000, preferably 2000 to 4000, may be used. In the present specification, the weight average molecular weight means a conversion value with respect to standard polystyrene measured by GPC (Gel Permeation Chromatograph), and unless otherwise specified, the term "molecular weight" means "weight average molecular weight". By setting the molecular weight to 1000 or more, the durability of the adhesive layer can be properly maintained, and the workability such as coating properties of the composition can be effectively maintained by setting it to 5000 or less.

As the epoxy compound, for example, an alicyclic epoxy compound or a glycidyl ether type epoxy compound may be used, and preferably a mixture of an alicyclic epoxy compound and a glycidyl ether type epoxy compound may be used.

As used herein, the term "alicyclic epoxy compound" may mean a compound including at least one epoxidized aliphatic ring group, and the term "glycidyl ether type epoxy compound" is a compound containing at least one glycidyl ether group. It may mean.

By containing an alicyclic epoxy compound in the epoxy compound, the glass transition temperature of the adhesive composition is increased to ensure sufficient durability of the adhesive layer, even if the protective film is formed on only one side, generation of cracks of the polarizer even under heat or thermal shock conditions Can be prevented.

In the alicyclic epoxy compound including an epoxidized aliphatic ring group, the epoxidized aliphatic ring group may mean, for example, a compound having an epoxy group formed on an alicyclic ring. In the above, the hydrogen atom constituting the alicyclic ring may be optionally substituted with a substituent such as an alkyl group. As an alicyclic epoxy compound, although the compound specifically illustrated below can be used, the epoxy compound which can be used is not limited to the following types, for example.

As an alicyclic epoxy compound, the epoxycyclohexylmethyl epoxycyclohexane carboxylate type compound represented by following General formula (1) can be illustrated first.

[Formula 1]

In Formula 1, R ₁ and R ₂ each independently represent a hydrogen or an alkyl group.

As used herein, unless otherwise specified, the term alkyl group means a straight, branched or cyclic alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The alkyl group may be optionally substituted with one or more substituents, or may be in an unsubstituted state.

As another example of an alicyclic epoxy compound, the epoxycyclohexane carboxylate compound of the alkanediol represented by following General formula (2) is mentioned.

[Formula 2]

In Formula 2, R ₃ and R ₄ each independently represent a hydrogen or an alkyl group, and n represents an integer of 2 to 20.

Moreover, as another example of an alicyclic epoxy compound, the epoxy cyclohexyl methyl ester type compound of the dicarboxylic acid represented by following formula (3) is mentioned.

[Formula 3]

In Formula 3, R ₅ and R ₆ each independently represent a hydrogen or an alkyl group, and p represents an integer of 2 to 20.

As another example of an alicyclic epoxy compound, the epoxycyclohexylmethyl ether type compound of polyethyleneglycol represented by following formula (4) is mentioned.

[Formula 4]

In Formula 4, R ₇ and R ₈ each independently represent a hydrogen or an alkyl group, and q represents an integer of 2 to 20.

As another example of an alicyclic epoxy compound, the epoxycyclohexyl methyl ether type compound of the alkanediol represented by following formula (5) is mentioned.

[Formula 5]

In Formula 5, R ₉ and R ₁₀ each independently represent a hydrogen or an alkyl group, and r represents an integer of 2 to 20.

As another example of an alicyclic epoxy compound, the diepoxy citris pyro type-compound represented by following formula (6) is mentioned.

[Formula 6]

In Formula 6, R ₁₁ and R ₁₂ each independently represent a hydrogen or an alkyl group.

As another example of an alicyclic epoxy compound, the diepoxy monospiro system compound represented by following formula (7) is mentioned.

[Formula 7]

In Formula 7, R ₁₃ and R ₁₄ each independently represent a hydrogen or an alkyl group.

As another example of an alicyclic epoxy compound, the vinylcyclohexene diepoxide compound represented by following formula (8) is mentioned.

[Formula 8]

In Formula 8, R ₁₅ represents hydrogen or an alkyl group.

As another example of an alicyclic epoxy compound, the epoxycyclopentyl ether compound represented by following formula (9) is mentioned.

[Formula 9]

In Formula 9, R ₁₆ and R ₁₇ each independently represent a hydrogen or an alkyl group.

As another example of an alicyclic epoxy compound, the diepoxy tricyclo decane compound represented by following General formula (10) is mentioned.

[Formula 10]

In Formula 10, R ₁₈ represents hydrogen or an alkyl group.

As an alicyclic epoxy compound, More specifically, an epoxycyclohexylmethyl epoxycyclohexane carboxylate compound, the epoxycyclohexane carboxylate compound of an alkanediol, the epoxycyclohexylmethyl ester compound of a dicarboxylic acid, or the epoxycyclohexylmethyl ether compound of an alkanediol Preference is given to using esters of 7-oxabicyclo [4,1,0] heptan-3-carboxylic acid with (7-oxa-bicyclo [4,1,0] hepto-3-yl) methanol (Compound wherein R ₁ and R ₂ in Formula 1 are hydrogen); Ester of 4-methyl-7-oxabicyclo [4,1,0] heptan-3-carboxylic acid with (4-methyl-7-oxa-bicyclo [4,1,0] hepto-3-yl) methanol Cargo (compound wherein in formula 1, R ₁ is 4-CH ₃ , R ₂ is 4-CH ₃ ); Esterified product of 7-oxabicyclo [4,1,0] heptan-3-carboxylic acid with 1,2-ethanediol (compound wherein R ₃ and R ₄ are hydrogen and n is 1 in Formula 2); Esters of (7-oxabicyclo [4,1,0] hepto-3-yl) methanol with adipic acid (compounds wherein R ₅ and R ₆ in the formula (3) are hydrogen and p is 2); Esters of (4-methyl-7-oxabicyclo [4,1,0] hepto-3-yl) methanol with adipic acid (wherein R ₅ and R ₆ in Formula 3 are 4-CH ₃ , p is 2 compound); And etherified compounds of (7-oxabicyclo [4,1,0] hepto-3-yl) methanol with 1,2-ethanediol (wherein R ₉ and R ₁₀ in the formula 5 are hydrogen and r is 1) One or more selected from the group consisting of) may be preferably used, but is not limited thereto.

In addition, since the glycidyl ether type epoxy compound is included in the epoxy compound, the glycidyl ether reactor forms a soft and polar chain in the adhesive layer after the curing reaction, thereby improving adhesion to the PVA polarizer of the adhesive layer. You can.

The glycidyl ether type epoxy compound may include, for example, an aliphatic polyhydric alcohol or an alkylene oxide thereof, such as polyglycidyl ether of an ethylene oxide or propylene oxide adduct.

In one example, when a mixture of an alicyclic epoxy compound and a glycidyl ether type epoxy compound is used as the epoxy compound, the alicyclic epoxy compound is 3,4-epoxycyclohexylmethyl, 3,4-epoxycyclo. Hexanecarboxylate, bis (3,4-epoxycyclohexylmethyl) adipatedicyclopentadiene dioxide, limonene dioxide or 4-vinylcyclohexenedioxide, and the like, and the glycidyl ether type epoxy As the compound, an epoxy compound having an epoxy group other than an alicyclic epoxy group may be used. That is, specific glycidyl ether type epoxy compounds include novolac epoxy, bisphenol A epoxy, bisphenol F epoxy, brominated bisphenol epoxy, n-butyl glycidyl ether and aliphatic glycidyl ether (C12 to 14 carbon atoms). ), 2-ethylhexylglycidyl ether, phenyl glycidyl ether, o-cresyl glycidyl ether, nonyl phenyl glycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglyci Dil ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl Ether, trimethylolpropane triglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane polyglycidyl ether, polyethyleneglycol diglycidyl ether or glycerin trigly Cylyl ether and the like can be exemplified, and also hydrogenated compounds of glycidyl ether or aromatic epoxy compound having a cyclic aliphatic skeleton such as 1,4-cyclohexanedimethanol diglycidyl ether and the like can be exemplified, Preferably glycidyl ethers having a cyclic aliphatic skeleton, preferably glycidyl ethers having a cyclic aliphatic skeleton having 3 to 20 carbon atoms, preferably 3 to 16 carbon atoms, more preferably 3 to 12 carbon atoms, Can be used, but is not limited thereto.

In this case, the epoxy compound may include 5 parts by weight to 40 parts by weight of the alicyclic epoxy compound and 5 parts by weight to 30 parts by weight of the glycidyl ether type epoxy compound, and preferably 15 to 40 alicyclic epoxy compounds. It may comprise 15 to 30 parts by weight and 15 to 30 parts by weight of the glycidyl ether type epoxy compound, more preferably 20 to 30 parts by weight of the alicyclic epoxy compound and 20 to 30 parts by weight of the glycidyl ether type epoxy compound It may include parts by weight. When the alicyclic epoxy compound is included in an amount of 5 parts by weight or more, the durability of the adhesive layer may be sufficiently secured, and when included in an amount of 40 parts by weight or less, there is no problem that the adhesion to the PVA polarizer is reduced, and the glycidyl ether When the type epoxy compound is included in 5 parts by weight or more, there is an effect of improving the adhesive strength, when included in 30 parts by weight or less does not cause a problem that the durability of the adhesive layer is weak.

The alicyclic epoxy compound and the glycidyl ether type epoxy compound may be included in a weight part of 3: 1 to 1: 3, within the above range, to improve the durability of the adhesive layer and the adhesion of the adhesive layer to the PVA polarizer. Can be maximized.

The said adhesive composition also contains a radically polymerizable compound. For example, the radically polymerizable compound may be an acrylic monomer. As used herein, the term radically polymerizable compound may mean a compound including at least one polymerizable functional group capable of participating in a crosslinking reaction, preferably a free radical polymerization reaction, in a molecular structure. As the polymerizable functional group, an allyl group, allyloxy group, acryloyl group, methacryloyl group or acrylonitrile may be exemplified, but is not limited thereto.

In one example, the acrylic monomer may include a hydrophilic acrylic monomer or a hydrophobic acrylic monomer, and preferably, may be a mixture of a hydrophilic acrylic monomer and a hydrophobic acrylic monomer.

For example, in order to improve adhesion to the PVA polarizer of the adhesive layer, the hydrophilic acrylic monomer may be included in the acrylic monomer.

As used herein, the term hydrophilic acrylic monomer may mean an acrylic monomer having hydrophilicity by simultaneously including a polymerizable functional group and a polar functional group in a molecular structure, and as the polar functional group, a hydroxy group, a carboxyl group or an alkoxy group may be exemplified. However, it is not limited thereto.

As the hydrophilic acrylic monomer, for example, one or more of the compounds represented by the following Chemical Formulas 11 to 13 may be used, and preferably, the compound represented by the following Chemical Formula 11 may be used, but is not limited thereto.

[Formula 11]

In Formula 11, R ₁₉ represents hydrogen or an alkyl group, A and B each independently represents an alkylene group or an alkylidene group, and n represents a number from 0 to 5.

[Formula 12]

In Formula 12, R represents hydrogen or an alkyl group, R ₂₀ represents hydrogen or -A ₃ -C (= 0) -OH, wherein A ₃ represents an alkylene group or an alkylidene group.

[Formula 13]

In Formula 13, R represents hydrogen or an alkyl group, R ₂₁ represents an alkyl group, A ₁ and A ₂ each independently represents an alkylene group or an alkylidene group.

As used herein, the term alkylene group or alkylidene group is a linear, branched or cyclic substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms, or It may be an alkylidene group, preferably a linear or branched alkylene group or alkylidene group having 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms.

N in the formula 11 may be more preferably 0 to 3, even more preferably 0 to 2.

In addition, in the compound of Formula 12, R ₁ may preferably represent hydrogen or — (CH ₂ ) _m —C (═O) —OH (m is an integer of 1 to 4).

In addition, in the compound of Formula 13, R ₃ is alkyl having 1 to 4 carbon atoms, and A ₁ and A ₂ may be each independently alkylene having 1 to 4 carbon atoms.

As a compound of the said Formula (11), 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acryl Latex, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, or 2-hydroxypropylene glycol (meth) acrylate, and the like can be exemplified. , Methacrylic acid or β-carboxyethyl (meth) acrylate, and the like can be exemplified. As the compound of Formula 13, 2- (2-ethoxyethoxy) ethyl (meth) acrylate can be exemplified. It is not limited to this.

In one example, the compound represented by Formula 11 may be used as the hydrophilic radical polymerizable monomer.

The acrylic monomer may include 10 parts by weight to 80 parts by weight of the hydrophilic monomer, preferably 20 parts by weight to 60 parts by weight of the hydrophilic monomer. When included in the above range, it is possible to improve the adhesion to the PVA polarizer of the pressure-sensitive adhesive layer.

In addition, in one example, the acrylic monomers may include one or more hydrophobic acrylic monomers for controlling adhesion, compatibility and glass transition temperature.

As the hydrophobic acrylic monomer in the above, for example, an acrylic acid ester of an aromatic compound, a methacrylic acid ester of an aromatic compound, a long chain alkyl group, for example, an alkyl acrylic having an alkyl group having 9 or more carbon atoms, preferably having 9 to 15 carbon atoms Elate or alkyl methacrylates or acrylic acid esters of alicyclic compounds or methacrylic acid esters of alicyclic compounds can be used.

In one example, as the hydrophobic acrylic monomer, a compound represented by Formula 14 and / or a compound represented by Formula 15 may be used.

[Formula 14]

In Formula 14, R ₂₂ represents hydrogen or an alkyl group, D represents an alkylene group or an alkylidene group, Q represents a single bond, an oxygen atom or a sulfur atom, Ar represents an aryl group, and p represents a number of 0 to 3. Indicates.

[Formula 15]

In Formula 15, R represents hydrogen or an alkyl group, and R ₂₃ represents a monovalent moiety derived from an alkyl group having 9 or more carbon atoms or an alicyclic compound.

In Formula 14, the term "single bond" refers to a case in which a separate atom is not present in a portion represented by Q, and a carbon atom of D or C (= 0) is directly connected to Ar.

In addition, in the formula (14), the aryl group refers to a monovalent moiety derived from a compound or derivative thereof including a structure in which benzene or two or more benzenes are bonded or condensed to each other. The aryl group may be, for example, an aryl group having 6 to 22 carbon atoms, preferably 6 to 16 carbon atoms, more preferably 6 to 13 carbon atoms, and for example, a phenyl group, a phenylethyl group, a phenylpropyl group, and a benzyl group. , Tolyl group, xylyl group (xylyl group) or naphthyl group and the like.

In addition, p in Chemical Formula 14 may be preferably 0 or 1.

In addition, in the compound of Formula 15, R ₂₃ may be preferably an alkyl group having 9 to 15 carbon atoms or a monovalent residue derived from an alicyclic compound having 3 to 20 carbon atoms, preferably 6 to 15 carbon atoms.

As the compound of Formula 14, phenoxy ethyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylthio-1-ethyl (meth) acrylate, 6- (4,6-dibromo-2 Isopropyl phenoxy) -1-hexyl (meth) acrylate, 6- (4,6-dibromo-2-sec-butyl phenoxy) -1-hexyl (meth) acrylate, 2,6-di Bromo-4-nonylphenyl (meth) acrylate, 2,6-dibromo-4-dodecyl phenyl (meth) acrylate, 2- (1-naphthyloxy) -1-ethyl (meth) acrylate , 2- (2-naphthyloxy) -1-ethyl (meth) acrylate, 6- (1-naphthyloxy) -1-hexyl (meth) acrylate, 6- (2-naphthyloxy) -1 -Hexyl (meth) acrylate, 8- (1-naphthyloxy) -1-octyl (meth) acrylate, 8- (2-naphthyloxy) -1-octyl (meth) acrylate, and the like can be exemplified. Phenoxy ethyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylthio-1-ethyl acrylate, and 8- (2-naph). Oxy) -1-octyl acrylate and 2- (1-naphthyloxy) -ethyl acrylate, preferably phenoxy ethyl (meth) acrylate and benzyl (meth) acrylate, etc. may be used, but not limited thereto. It doesn't happen.

In addition, the compound of formula 15, isobornyl (meth) acrylate (isobornyl (meth) acrylate), cyclohexyl group (meth) acrylate, norbornanyl (meth) acrylate, norbornenyl (norbornenyl) (meth) acrylate, dicyclopentadienyl (meth) acrylate, ethynylcyclohexane (meth) acrylate, ethynylcyclohexene (meth) acrylate or ethynyl decahydronaphthalene (meth) acrylate And the like, and preferably, isobornyl (meth) acrylate and the like may be exemplified, but is not limited thereto.

The acrylic monomers, for example, may be used in a proportion of 60 parts by weight or less, preferably 10 parts by weight to 60 parts by weight of the hydrophobic acrylic monomers. When the hydrophobic acrylic monomer is included in less than 10 parts by weight, the hydrophilic functional groups are increased, the water resistance of the polarizing plate is weak, and when used in excess of 60 parts by weight may be weak adhesion to the PVA polarizer.

In addition, for example, when the compound of Formula 14 is used as the hydrophobic compound, the compound may be included, for example, 0 parts by weight to 40 parts by weight, preferably 10 parts by weight to 30 parts by weight. In addition, when the compound of Formula 15 is used, the compound may be included, for example, 0 parts by weight to 30 parts by weight, preferably 5 parts by weight to 20 parts by weight. At such a weight ratio, it is possible to maximize the adhesion to the substrate, for example, the acrylic protective film to be described later.

In one example, the adhesive composition may further comprise a reactive oligomer. The term "reactive oligomer" refers to a compound in which two or more monomers are polymerized, and have a polymerizable functional group capable of participating in a crosslinking reaction, for example, a compound having a polymerizable functional group of the type described in the above-mentioned radically polymerizable compound section. Is a generic term.

As the reactive oligomer, what is called photoreactive oligomer in the art, urethane acrylate, polyester acrylate, polyether acrylate or epoxy acrylate may be used, and urethane acrylate may be preferably used. However, the present invention is not limited thereto.

In the adhesive composition, the reactive oligomer may be included, for example, 1 part by weight to 40 parts by weight, preferably 5 parts by weight to 20 parts by weight. In this weight ratio, it is possible to maximize the synergistic effect of the glass transition temperature of the adhesive layer.

The adhesive composition may further include a cationic initiator as an initiator for initiating a curing reaction. As a cation initiator, if it can start a cationic reaction by application or irradiation of light, it can use without a restriction | limiting, For example, the cationic photoinitiator which starts a cationic reaction by irradiation of an active energy ray can be used.

In one example, as a cationic photoinitiator, an ionization cation initiator of an onium salt or an organometallic salt series or a non-ionization compound such as an organic silane or a latent sulfonic acid series or other non-ionizing compounds Cationic photoinitiators can be used. Examples of the onium salt-based initiator include a diaryliodonium salt, a triarylsulfonium salt, an aryldiazonium salt, and the like. As the zero, iron arene and the like can be exemplified. Examples of the organosilane-based initiator include o-nitrobenzyl triaryl silyl ether and triaryl silyl peroxide. Or an acyl silane (acyl silane) and the like can be exemplified, the latent sulfuric acid-based initiator may be exemplified by α-sulfonyloxy ketone or α-hydroxymethylbenzoin sulfonate and the like, but is not limited thereto. . In addition, a mixture of an iodine-based initiator and a photosensitizer may be used as the cationic initiator.

As a cation initiator, it is preferable to use an ionization cation photoinitiator, It is more preferable to use an onium salt type | mold ionization cation photoinitiator, It is more preferable to use the triarylsulfonium salt type | mold ionization cation photoinitiator, However, it restricts to this It doesn't happen.

The adhesive composition may include 0.01 parts by weight to 10 parts by weight of the cationic initiator, preferably 0.1 parts by weight to 5 parts by weight. In the above ratio, it is possible to provide an adhesive composition having excellent curing efficiency and physical properties after curing.

The adhesive composition may further include a photoinitiator as a radical initiator capable of initiating a polymerization or crosslinking reaction such as an acrylic monomer. As the photoinitiator, for example, an initiator such as a benzoin compound, a hydroxyketone compound, an aminoketone compound or a phosphine oxide compound can be used, and preferably a phosphine oxide compound or the like can be used. As a photoinitiator, More specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylanino acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1one, 1-hydroxycyclohexylphenyl Ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl Ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-amino Anthraquinone, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2-chloro thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoate Aromatic acid ester, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], bis (2,4,6-trimethylbenzoyl) -phenyl-phosphineoxide and 2 , 4,6-trimethylbenzoyl-diphenyl-phosphineoxide and the like can be exemplified, but is not limited thereto.

In the adhesive composition, the photoinitiator may be included in an amount of 0.1 parts by weight to 10 parts by weight, preferably 0.5 parts by weight to 5 parts by weight, and in this range, may induce effective polymerization or crosslinking, and may prevent degradation of physical properties by reaction residues. Can be.

The adhesive composition may further use an initiator, so-called long wavelength photoinitiator, which absorbs long-wavelength active energy rays and generates radicals as a radical initiator. These initiators may be used alone or in combination with other types of initiators.

That is, in order to protect a polarizer from ultraviolet-ray, the sunscreen etc. may be mix | blended with the protective film contained in a polarizing plate. In this case, upon irradiation of electromagnetic waves for curing the adhesive composition, electromagnetic waves in a short wavelength range, for example, about 365 nm or less, may be absorbed by the protective film so that an appropriate curing reaction may not proceed. Thus, to avoid this, the radical initiator preferably comprises an initiator capable of generating radicals by absorbing at least long wavelengths, for example electromagnetic waves in the wavelength range of about 365 nm or more.

As said long wavelength photoinitiator, diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, etc. can be used, for example. For example, Darocur TPO, Irgacure 819, etc. of Sivage, Switzerland may be illustrated, but is not limited thereto.

The adhesive composition may further include additives such as photosensitizers, antioxidants or adhesion promoters, and known oligomer components for controlling adhesion performance, brittleness, and the like, as necessary.

In one example, the adhesive composition may be formulated in a solventless type. The solvent-free type may mean an adhesive composition of a type that does not include an organic or aqueous solvent component used for diluting a component constituting the adhesive composition. By forming the adhesive composition into a solvent-free type, it is not necessary to volatilize the solvent in the process of forming the adhesive layer, and can effectively maintain the thickness uniformity and the like, and can also effectively prevent a phenomenon such as curling in the polarizer.

The adhesive composition may have a viscosity at 25 ° C. of 5 cps to 1,000 cps, preferably 10 cps to 100 cps. By adjusting the viscosity in the above range, it is possible to ensure process efficiency, ease of thickness control and thickness uniformity, and to effectively maintain physical properties such as adhesive properties.

The method for forming the adhesive layer using the composition on the polarizer is not particularly limited. For example, the adhesive composition is applied to the polarizer and cured, or the adhesive composition is applied to the polarizer, and the adhesive layer is laminated again. Thereafter, a method of curing the applied adhesive composition may be used. In this case, curing of the adhesive composition may be carried out in such a manner as to irradiate an active energy ray of a suitable intensity so that polymerization or crosslinking reaction of the components may be induced in consideration of each component.

The adhesive layer has a thickness of 0.1 μm to 30 μm, preferably 0.5 μm to 15 μm, and more preferably 1 μm to 10 μm. By adjusting the thickness of the adhesive layer to 0.1 μm or more, it is possible to maintain excellent water resistance of the polarizing plate, and also to adjust to 30 μm or less, it is possible to form a thin polarizing plate of a uniform adhesive layer and excellent physical properties.

The adhesive layer contained in the said polarizing plate has a 1st surface and a 2nd surface, and the peeling force with respect to the alkali free glass in the said 1st surface and the 2nd surface differs. In one example, the second surface exhibits a high peeling force against the alkali-free glass as compared to the first surface, the first surface is attached to the adhesive layer, and the second surface attaches the polarizing plate to the liquid crystal panel. It may be an adhesive surface for making. As used herein, the term "alkali free glass" means a glass containing almost no alkali components and containing aluminum oxide instead of an alkali component.

In one example, the pressure-sensitive adhesive layer may be a single layer pressure-sensitive adhesive layer having a first surface and a second surface. In the above, the single layer means a case where the pressure-sensitive adhesive layer is formed of one pressure-sensitive adhesive layer, and thus, for example, the pressure-sensitive adhesive layer having a structure in which two or more pressure-sensitive adhesives are laminated is excluded from the pressure-sensitive adhesive layer of the single layer.

FIG. 2 exemplarily shows a single-layer adhesive layer 10 having a first surface 10A and a second surface 10B.

By setting the peeling force with respect to the alkali free glass of the 1st surface adhering to a polarizer in the said adhesive layer low, the shrinkage or expansion phenomenon of a polarizer can be suppressed in severe conditions, such as high temperature or high humidity conditions. Moreover, the 2nd surface 10B which adheres a polarizing plate to a liquid crystal panel can have high peeling force, can make it excellent wettability with respect to a to-be-adhered body, and can improve adhesive reliability.

In one example, the pressure-sensitive adhesive layer may be controlled such that the difference between the peeling force on the alkali free glass of the first surface and the peeling force on the alkali free glass of the second surface satisfies the following general formula (1).

[Formula 1]

X ₂ -X ₁ 〉 50 gf / 25mm

In said general formula 1, said X <_1> shows the peeling force with respect to the alkali free glass of a 1st surface, and said X <_2> shows the peeling force with respect to the alkali free glass of a 2nd surface.

In one example, the first surface has a peel force against alkali-free glass of 5 gf / 25mm to 100 gf / 25mm, preferably 8 gf / 25mm to 70 gf / 25mm, more preferably 10 gf / 25mm to 60 gf / 25mm, more preferably 15 gf / 25mm to 50 gf / 25mm. In addition, the second surface has a peel force against an alkali free glass of 100 gf / 25mm to 1,000 gf / 25mm, preferably 150 gf / 25mm to 800 gf / 25mm, more preferably 200 gf / 25mm to 700 gf / 25mm, more preferably 250 gf / 25mm to 650 gf / 25mm. Peeling force is the peeling force measured by the method prescribed | regulated in the Example mentioned later in the above. While the peeling force on the alkali-free glass of the second surface is controlled higher than the peeling force on the alkali-free glass of the first surface in a range of more than 50 gf / 25 mm, the peeling force of the first and second surfaces is described above. By controlling each to one range, it can be made to exhibit the outstanding wettability with respect to a liquid crystal panel, effectively suppressing shrinkage | contraction and expansion phenomenon of a polarizer in high temperature or high humidity conditions.

As described above, the pressure-sensitive adhesive layer having different peeling forces on the first surface and the second surface while being a single layer can be produced, for example, by forming a gradient in which the elastic modulus changes along the thickness direction of the pressure-sensitive adhesive layer. Referring to FIG. 2, in one example, the pressure-sensitive adhesive layer 10 has a tensile modulus along the thickness direction (arrow T direction in FIG. 3) from the first surface 10A to the second surface direction 10B. A gradient of may be formed. The change in tensile modulus in the thickness direction in the above means a case where the tensile modulus of the pressure-sensitive adhesive layer increases or decreases continuously or intermittently along the thickness direction. Specifically, the tensile modulus may vary along the thickness direction such that the highest tensile modulus appears on the first surface 10A and the lowest tensile modulus appears on the second surface 10B.

In order to give a change along the thickness direction to the tensile modulus of the pressure-sensitive adhesive layer as described above, for example, a method of controlling the degree of curing of the pressure-sensitive adhesive layer to vary depending on the thickness direction can be used. For example, as will be described later, in the case of constituting the pressure-sensitive adhesive layer using the ultraviolet-curable pressure-sensitive adhesive composition, if the thickness of the pressure-sensitive adhesive composition is applied and the amount of ultraviolet light applied during curing of the composition is controlled appropriately, the thickness direction Thus, the pressure-sensitive adhesive layer in which the storage modulus changes can be produced. That is, when the pressure-sensitive adhesive layer is manufactured in the same manner as above, the irradiated ultraviolet rays are transmitted or transmitted in the thickness direction of the pressure-sensitive adhesive composition, and are extinguished or absorbed in response to an internal photoinitiator or the like. The lower the intensity along the thickness direction of the composition becomes weaker the intensity of the ultraviolet light that induces the curing reaction, the degree of curing can be controlled differently along the thickness direction. In the present invention, in some cases, the pressure-sensitive adhesive layer in which the degree of curing is changed in the thickness direction can also be implemented by a method of blending an appropriate amount of ultraviolet absorber or the like into the photocurable pressure-sensitive adhesive composition. That is, the ultraviolet absorber blended into the pressure-sensitive adhesive composition absorbs the ultraviolet rays applied to the composition during the curing process, and as a result, a variation in the amount of ultraviolet radiation can be induced depending on the thickness direction, and the degree of curing can be controlled differently.

When the tensile modulus is controlled to change along the thickness direction as described above, the average tensile modulus of the pressure-sensitive adhesive is 0.1 MPa to 500 MPa, preferably 10 MPa to 400 MPa, more preferably 20 MPa to 300 MPa at 25 ° C. More preferably 45 MPa to 200 MPa. By controlling the average value of the tensile modulus in the above range, the polarizing plate can effectively suppress the light leakage phenomenon and the like to exhibit excellent durability under high temperature or high humidity conditions. In addition, the said tensile elasticity modulus is measured by the method described in the Example mentioned later.

The thickness of the pressure-sensitive adhesive layer implemented as described above is not particularly limited, and may be controlled within a range of, for example, 20 μm to 80 μm, preferably 25 μm to 60 μm. If the thickness of the pressure-sensitive adhesive layer is less than 20 μm, the efficiency of suppressing the shrinkage or expansion of the polarizer may be reduced, or the efficiency of implementing the pressure-sensitive adhesive layer having different degrees of curing in the thickness direction may be lowered according to the above-described curing process, and 80 μm may be reduced. If it exceeds, there exists a possibility that it may become an obstacle to thinning of a polarizing plate.

The method of forming an adhesive layer is not specifically limited. For example, the conventional room temperature curing type, moisture curing type, heat curing type or photocurable pressure sensitive adhesive composition can be cured and formed, and preferably UV curable pressure sensitive adhesive composition can be formed by curing.

In one example, the pressure-sensitive adhesive layer may include a so-called interpenetrating polymer network (hereinafter, referred to as "IPN"). The term "IPN" may refer to a state in which at least two or more kinds of crosslinked structures exist in the pressure-sensitive adhesive layer, and in one example, the crosslinked structures may be entangled with each other, or linked or infiltrated with each other. may be in a penetrating state. When the pressure-sensitive adhesive layer contains an IPN, a polarizing plate having excellent durability under severe conditions and excellent in workability, optical characteristics and light leakage suppression ability can be realized.

When the pressure-sensitive adhesive layer includes an IPN structure, the pressure-sensitive adhesive layer may include, for example, a crosslinked structure including an acrylic polymer present in a crosslinked state and a crosslinked structure including a polymerized photopolymerizable compound.

In the acrylic polymer by, for example, a weight average molecular weight _{(M w: Weight Average Molecular Weight} ) This may be an acrylic polymer more than 500,000. The molecular weight of a polymer is made into 500,000 or more, and the adhesive layer which has the outstanding durability under severe conditions can be formed. The upper limit of the molecular weight is not particularly limited. For example, the upper limit of the molecular weight can be adjusted in the range of 2.5 million or less in consideration of the durability of the pressure-sensitive adhesive and the coating property of the composition.

In one example, the acrylic polymer may be a polymer including a (meth) acrylic acid ester monomer as a polymer unit.

As the (meth) acrylic acid ester monomer, for example, alkyl (meth) acrylate can be used, and alkyl (meth) having an alkyl group having 1 to 14 carbon atoms in consideration of control of cohesion, glass transition temperature and adhesion. Acrylate can be used. Such monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) Acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (Meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, tetradecyl (meth) acrylate, and the like can be exemplified, and one or more of the above can be used.

The polymer may further include a crosslinkable monomer as a polymerized unit, and preferably 50 parts by weight to 99.9 parts by weight of the (meth) acrylic acid ester monomer and 0.1 parts by weight to 50 parts by weight of the crosslinkable monomer in a polymerized form. It may be a polymer containing. In the above, the "crosslinkable monomer" includes a copolymerizable functional group and a crosslinkable functional group in the molecule at the same time, and may be copolymerized with the (meth) acrylic acid ester monomer and the monomer represented by the following formula (16). It means the monomer which can provide a crosslinkable functional group at the terminal.

The crosslinkable monomer may play a role in controlling the durability, adhesion and cohesion of the pressure-sensitive adhesive, and may provide, for example, a nitrogen-containing functional group such as a hydroxyl group, a carboxyl group, an epoxy group, an isocyanate group or an amino group to the polymer, In addition, a monomer copolymerizable with the (meth) acrylic acid ester monomer may be used. Various monomers are known in the art to play such a role, and in the present invention, all such monomers can be used. Specific examples of the crosslinkable monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylic Hydroxy group-containing monomers such as latex, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate or 2-hydroxypropylene glycol (meth) acrylate; (Meth) acrylic acid, 2- (meth) acryloyloxy acetic acid, 3- (meth) acryloyloxy propyl acid, 4- (meth) acryloyloxy butyl acid, acrylic acid duplex, itaconic acid, maleic acid and Carboxyl group-containing monomers such as maleic anhydride, epoxy group-containing monomers such as glycidyl (meth) acrylate, or nitrogen-containing monomers such as (meth) acrylamide, N-vinyl pyrrolidone or N-vinyl caprolactam, and the like. It may be used, but one or a mixture of two or more of these may be used, but is not limited thereto.

The acrylic polymer may further comprise suitable comonomers in addition to those described above.

For example, the polymer may further include a monomer represented by Formula 16 as a polymerized unit.

[Formula 16]

In Formula 16, R represents hydrogen or an alkyl group, A represents alkylene, R ₂₄ represents an alkyl group or an aryl group, and n represents a number from 1 to 50.

The monomer of Formula 16 imparts an alkylene oxide group to the polymer. In one example, the alkylene oxide group may be a straight, branched or cyclic alkylene oxide having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms. Such an alkylene oxide group exhibits a low haze of the pressure-sensitive adhesive layer, and can also effectively suppress light leakage when applied to the polarizing plate. In addition, the alkylene oxide group may be to maintain the peeling force at an appropriate level, even when the elastic modulus of the pressure-sensitive adhesive layer is increased.

In Formula 16, R may preferably be hydrogen or an alkyl group having 1 to 4 carbon atoms, more preferably hydrogen or a methyl group.

In addition, in Formula 16, A may be a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The groups can have a straight, branched or cyclic structure.

In the above Formula 16, when R ₂₄ is an alkyl group, the alkyl group may be a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. And such alkyl groups may have a straight, branched or cyclic structure.

In addition, when R ₂₄ is an aryl group in Formula 16, the aryl group may be an aryl group having 6 to 20 carbon atoms, 6 to 16 carbon atoms, or 6 to 12 carbon atoms.

In addition, n in Formula 16 may be more preferably 1 to 25, still more preferably 1 to 15, and more preferably 1 to 6.

 Specific examples of the monomer of the formula (16) include alkoxy alkylene glycol (meth) acrylic acid ester, alkoxy dialkylene glycol (meth) acrylic acid ester, alkoxy trialkylene glycol (meth) acrylic acid ester, alkoxy tetraalkylene glycol (meth) acrylic acid Ester, alkoxy polyethylene glycol (meth) acrylic acid ester, phenoxy alkylene glycol (meth) acrylic acid ester, phenoxy dialkylene glycol (meth) acrylic acid ester, phenoxy trialkylene glycol (meth) acrylic acid ester, phenoxy tetraalkyl Lenglycol (meth) acrylic acid ester or phenoxy polyalkylene glycol (meth) acrylic acid ester, etc. can be mentioned, One or more types of these monomers can be contained in a polymer.

When the acrylic polymer includes the monomer of Formula 16, the acrylic polymer may include, for example, 40 parts by weight to 99.9 parts by weight of (meth) acrylic acid ester monomer; 10 parts by weight to 50 parts by weight of the monomer of Formula 16 and 0.01 parts by weight to 30 parts by weight of the crosslinkable monomer may be included. When included in such a weight ratio, not only can light leakage be effectively suppressed, but also the peel force can be maintained at an appropriate level even when the elastic modulus of the pressure-sensitive adhesive layer is increased.

The polymer may further include a comonomer represented by the following formula (17) in view of controlling the glass transition temperature or imparting other functionalities.

[Formula 17]

In Formula 17, R ₂₅ to R ₂₇ each independently represent hydrogen or alkyl, and R ₂₈ is cyano; Phenyl unsubstituted or substituted with alkyl; Acetyloxy; Or COR ₂₉ , wherein R ₂₉ represents amino or glycidyloxy unsubstituted or substituted with alkyl or alkoxyalkyl.

Specific examples of the monomer of Formula 17 include nitrogen-containing monomers such as (meth) acrylonitrile, (meth) acrylamide, N-methyl (meth) acrylamide or N-butoxy methyl (meth) acrylamide; Styrene-based monomers such as styrene or methyl styrene; Glycidyl (meth) acrylate; Or a carboxylic acid vinyl ester such as vinyl acetate, or the like, or a heterogeneous compound, but is not limited thereto.

When the acrylic polymer includes the monomer of Formula 17, the ratio is preferably 20 parts by weight or less.

Such acrylic polymers can be prepared through conventional polymerization methods known in the art. For example, (meth) acrylic acid ester monomers, crosslinkable monomers, and / or monomers of Formula 16, etc., as described above, are suitably blended according to the desired weight ratio to prepare a monomer mixture, which is solution polymerization. And photopolymerization, bulk polymerization, suspension polymerization, or emulsion polymerization. If necessary in this process, a suitable polymerization initiator or chain transfer agent may be used together.

The pressure-sensitive adhesive layer may further include a polyfunctional crosslinking agent for crosslinking the acrylic polymer, and as such a crosslinking agent, for example, a general crosslinking agent such as an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent may be used. The use of isocyanate crosslinking agents may be preferred, but is not limited thereto. As an isocyanate crosslinking agent, polyfunctional isocyanate compounds, such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, tetramethyl xylene diisocyanate, or naphthalene diisocyanate, or the said polyfunctional Compounds obtained by reacting an isocyanate compound with a polyol compound such as trimethylol propane and the like can be cited. Examples of the epoxy crosslinking agent include ethylene glycol diglycidyl ether, triglycidyl ether, and trimethylolpropane triglycidyl ether, N, N, N. And one or more selected from the group consisting of ', N'-tetraglycidyl ethylenediamine and glycerin diglycidyl ether, and the aziridine crosslinking agent is N, N'-toluene-2,4-bis (1- Aziridinecarboxamide), N, N'-diphenylmethane-4,4'- One or more selected from the group consisting of s (1-aziridinecarboxamide), triethylene melamine, bisisoprotaloyl-1- (2-methylaziridine) and tri-1-aziridinylphosphineoxide May be, but is not limited thereto. In addition, examples of the metal chelate crosslinking agent include compounds in which polyvalent metals such as aluminum, iron, zinc, tin, titanium, antimony, magnesium, and / or vanadium are coordinated with acetyl acetone, ethyl acetoacetate, and the like, but are not limited thereto. It doesn't happen.

The multifunctional crosslinking agent may be included in the pressure-sensitive adhesive, for example, in an amount of 0.01 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the acrylic polymer described above. Within such a range, the cohesion force and durability of an adhesive can be kept excellent.

The multifunctional crosslinking agent may, for example, react with a crosslinkable functional group of an acrylic polymer in the process of forming an adhesive layer such as a aging process to crosslink the polymer.

In the pressure-sensitive adhesive layer of the IPN structure, a crosslinked structure including a photopolymerizable compound polymerized together with a crosslinked structure implemented by an acrylic polymer crosslinked by the multifunctional crosslinking agent may be included.

That is, the pressure-sensitive adhesive composition may further include a photopolymerizable compound as a component for implementing a kind of crosslinked structure different from the crosslinked structure in which the acrylic polymer is crosslinked. The term "photopolymerizable compound" means a compound containing at least two or more photopolymerizable functional groups in a molecular structure so as to be polymerized by irradiation of light to implement a crosslinked structure. In addition, the photopolymerizable functional group is a functional group that can be polymerized or crosslinked by irradiation with light, and examples thereof include a functional group including an ethylenically unsaturated double bond such as acryloyl group or methacryloyl group, and the like. It doesn't happen. In addition, the term "irradiation of light" means the irradiation of electromagnetic waves, and examples of the electromagnetic waves include microwaves, infrared rays (IR), ultraviolet rays (UV), X rays and γ rays, and α-particle rays ( Particle beams such as α-particle beams, proton beams, neutron beams and electron beams may be included.

As the photopolymerizable compound, for example, multifunctional acrylate (MFA) may be used.

As the polyfunctional acrylate, any compound having two or more (meth) acryloyl groups in the molecule can be used without limitation. For example, 1, 4- butanediol di (meth) acrylate, 1, 6- hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethyleneglycol di (meth) acrylate, neopentyl Neopentylglycol adipate di (meth) acrylate, hydroxyl puivalic acid neopentylglycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dish Clopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, di (meth) acryloxy ethyl isocyanurate, allylated cyclohexyl di (meth) acrylate, tricyclodecane Dimethanol (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate Neopentyl glycol modified trimethylpropane di (meth) acrylate, adamantane di (meth) acrylate or 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene difunctional acrylates such as (fluorine) and the like; Trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide Trifunctional acrylates such as modified trimethylolpropane tri (meth) acrylate, trifunctional urethane (meth) acrylate or tris (meth) acryloxyethyl isocyanurate; Tetrafunctional acrylates such as diglycerin tetra (meth) acrylate or pentaerythritol tetra (meth) acrylate; 5-functional acrylates, such as propionic acid modified dipentaerythritol penta (meth) acrylate; And dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate or urethane (meth) acrylate (ex. Isocyanate monomers and trimethylolpropane tri (meth) acrylate Six functional acrylates, such as a reactant, etc. can be used, In some cases, it is known as a photocurable oligomer in this field, and various urethane acrylates, polycarbonate acrylates, polyester acrylates, polyether acrylates Or epoxy acrylate may be used.

The multifunctional acrylate may be used in one kind or a mixture of two or more kinds, and a molecular weight of less than 1,000, it is preferable to use an acrylate having a trifunctional or more than in terms of durability, but is not limited thereto.

As said polyfunctional acrylate, it is preferable to use what contains a ring structure among frame | skeletal structures. By using such an acrylate, the shrinkage or expansion of a polarizer can be suppressed more effectively, and the light leakage suppression effect can also be improved. Ring structures included in the polyfunctional acrylate include carbocyclic structures or heterocyclic structures; Or any of a monocyclic or polycyclic structure. Examples of the polyfunctional acrylate including a ring structure include monomers having isocyanurate structures such as tris (meth) acryloxy ethyl isocyanurate and isocyanate-modified urethane (meth) acrylates (ex. Isocyanate monomers and trimethyl) 6 functional acrylates, such as a reactant of rolled propane tri (meth) acrylate, etc., etc. are mentioned, but it is not limited to this.

In the pressure-sensitive adhesive layer or pressure-sensitive adhesive composition, the multifunctional acrylate may be included in an amount of 20 parts by weight to 200 parts by weight with respect to 100 parts by weight of the acrylic polymer, thereby more effectively controlling the tensile modulus of the pressure-sensitive adhesive layer, and also having excellent durability. I can keep it.

The pressure-sensitive adhesive layer may further include a ultraviolet absorber, which may improve the efficiency of forming a pressure-sensitive adhesive of a single layer having a different peel force on the first and second surfaces described above. That is, it is necessary to perform irradiation of light, for example, irradiation of ultraviolet rays, in order to cure the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer. For example, in order to form a sheet-shaped pressure-sensitive adhesive, when the pressure-sensitive adhesive composition is coated to a predetermined thickness and irradiated with ultraviolet rays from one side of the coating layer, the surface of the coating layer to which the ultraviolet rays are irradiated is sufficiently cured to exhibit high elastic modulus, As the ultraviolet light proceeds to the lower part of the coating layer along the thickness direction, the ultraviolet light is absorbed into the coating layer by the ultraviolet absorbent present in the coating layer. Therefore, the amount of ultraviolet rays that reach the lower portion along the thickness direction starting from the surface of the coating layer to which ultraviolet rays are irradiated decreases, and the lowermost coating layer has the least amount of ultraviolet rays, so that the degree of hardening is the least. As a result, in the sheet-like coating layer, a gradient of elastic modulus in which the elastic modulus changes along the thickness direction is formed. In the above, the elastic modulus means tensile modulus or storage modulus. When the elastic modulus is changed along the thickness direction in the sheet-shaped pressure-sensitive adhesive layer as described above, the surface of the coating layer on which the elastic modulus is high, that is, the ultraviolet ray is irradiated at the time of curing, exhibits a low peeling force, but the opposite side has a high peeling force. Can be represented.

As a ultraviolet absorber, if the optical property, elasticity modulus, re-peelability, workability, peeling force, etc. of an adhesive layer are not impaired, it can use without a restriction | limiting in particular.

As a ultraviolet absorber, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (3 ', 5'- di-tert- butyl-2'-hydroxyphenyl) benzotriazole, 2 -(5'-tert-butyl-2'-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-5- (1,1,3,3, tetramethylbutyl) phenyl) benzotriazole, 2 -(3 ', 5'-di-tert-butyl-2'-hydroxyphenyl) -5-benzotriazole, 2- (3'-tert-butyl-2'-hydroxyphenyl-5'-methylphenyl) -5-benzotriazole, 2- (3'-sec-butyl-5'-tert-butyl-2'-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-4'-octyloxyphenyl 2- (2'-hydroxyphenyl) -benzotriazole, such as phenyl) -5-benzotriazole or 2- (3 ', 5'-di-tert-butyl-2'-hydroxyphenyl) benzotriazole Benzotriazole compounds such as compounds of the class; 4-hydroxy, 4-methoxy, 4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2 ', 4'-trihydroxy or 2'-hydroxy- Benzophenone compounds such as 2-hydroxy benzophenone series compounds having 4,4'-dimethoxy functional groups; 4-tert-butyl-phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoyl resorcinol, bis (4-tert-butyl-benzoyl) resorcinol, benzoyl resorcinol, 2,4 -Di-tert-butylphenyl-3,5'-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-4hydroxybenzoate, octadecyl 3, Substituted benzoic acids such as 5-di-tert-butyl-4-hydroxybenzoate or 2-methyl-4,6-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate Benzoic acid ester compounds such as compounds having an ester structure; Or a triazine compound may be used, but is not limited thereto.

In the pressure-sensitive adhesive composition, the ultraviolet absorber may be included in an amount of 10 parts by weight or less based on 100 parts by weight of the acrylic polymer, or 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the photopolymerizable compound, but is not limited thereto. . The content of the ultraviolet absorbent may be changed in consideration of the curing conditions, the desired elastic modulus or the peel force characteristics of the pressure-sensitive adhesive composition. However, when the content of the ultraviolet absorber is excessively increased, the amount of ultraviolet absorbing of the coating liquid is excessively increased, which may make it difficult to implement the pressure-sensitive adhesive layer whose elastic modulus changes along the thickness direction.

The pressure-sensitive adhesive composition may further include a radical initiator to effectively induce a polymerization reaction of the photopolymerizable compound. In one example, the radical initiator may be a photoinitiator, and a specific kind of photoinitiator may be appropriately selected in consideration of curing rate and yellowing potential. For example, a benzoin type, a hydroxy ketone type, an amino ketone type, or a phosphine oxide type photoinitiator can be used. An initiator may be used by mixing one or more kinds of the above.

The pressure-sensitive adhesive composition may include 0.2 to 20 parts by weight, preferably 0.5 to 10 parts by weight, and more preferably 1 to 5 parts by weight, based on 100 parts by weight of the acrylic polymer. The photoinitiator may be included in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the multifunctional acrylate. Through such control, it is possible to effectively induce the reaction of the multifunctional acrylate, and also to prevent the deterioration of the adhesive properties due to the remaining components after curing.

The pressure-sensitive adhesive layer may further include a silane coupling agent. The silane coupling agent improves the adhesiveness and adhesion stability of the pressure-sensitive adhesive to improve heat resistance and moisture resistance, and also improves adhesion reliability even when the pressure-sensitive adhesive is left for a long time under severe conditions. As the silane coupling agent, for example, γ-glycidoxypropyl triethoxy silane, γ-glycidoxypropyl trimethoxy silane, γ-glycidoxypropyl methyldiethoxy silane, γ-glycidoxypropyl tri Ethoxy silane, 3-mercaptopropyl trimethoxy silane, vinyltrimethoxysilane, vinyltriethoxy silane, γ-methacryloxypropyl trimethoxy silane, γ-methacryloxy propyl triethoxy silane, γ- Aminopropyl trimethoxy silane, γ-aminopropyl triethoxy silane, 3-isocyanato propyl triethoxy silane, γ-acetoacetatepropyl trimethoxysilane, acetoacetatepropyl triethoxy silane, β-cyano Acetyl trimethoxy silane, β-cyanoacetyl triethoxy silane, acetoxy aceto trimethoxy silane and the like can be used, and one or more of the above can be used. In this invention, although it is preferable to use the silane coupling agent which has an acetoacetate group or (beta) -cyanoacetyl group, it is not limited to this. In the pressure-sensitive adhesive layer, the silane coupling agent may be included in an amount of 0.01 parts by weight to 5 parts by weight, preferably 0.05 parts by weight to 1 parts by weight, based on 100 parts by weight of the acrylic polymer, thereby effectively maintaining adhesion and durability.

The pressure-sensitive adhesive layer may further include a tackifying resin. As the tackifying resin, for example, a hydrocarbon-based resin or a hydrogenated substance thereof, a rosin resin or a hydrogenated substance thereof, a rosin ester resin or a hydrogenated substance thereof, a terpene resin or a hydrogenated substance thereof, a terpene phenol resin or a hydrogenated substance thereof, or a polymerized rosin One kind or a mixture of two or more kinds of resins or polymerized rosin ester resins can be used. The tackifying resin may be included in an amount of 1 part by weight to 100 parts by weight with respect to 100 parts by weight of the acrylic polymer.

The pressure-sensitive adhesive layer further includes one or more additives selected from the group consisting of epoxy resins, curing agents, ultraviolet stabilizers, antioxidants, colorants, reinforcing agents, fillers, antifoaming agents, surfactants and plasticizers, in a range that does not affect the desired effect. It may further include.

As including the above components, the method for producing the pressure-sensitive adhesive layer having different peeling force on the first surface and the second surface is not particularly limited. For example, the pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition containing each of the above-mentioned components in a sheet shape, and the step of curing the coating layer by irradiating ultraviolet rays from one side of the sheet shape to prepare a pressure-sensitive adhesive layer The ultraviolet rays may be absorbed in the coating layer while advancing along the thickness direction of the coating layer, thereby forming a gradient of tensile modulus along the thickness direction of the cured pressure-sensitive adhesive layer.

That is, the pressure-sensitive adhesive can be produced in such a manner that the pressure-sensitive adhesive composition or the coating liquid prepared therefrom is applied to an appropriate process substrate by a conventional means such as a bar coater or a comma coater and cured.

In this case, by controlling the coating thickness of the pressure-sensitive adhesive composition, the degree of irradiation of ultraviolet rays or the like, or by including an ultraviolet absorber in the composition as necessary, the irradiated ultraviolet rays are absorbed in the process of proceeding in the thickness direction of the coating layer, accordingly Gradients may be formed.

FIG. 3 is a diagram schematically illustrating a manufacturing process of one exemplary pressure-sensitive adhesive, and as shown in FIG. 3, the pressure-sensitive adhesive may be formed by irradiating ultraviolet rays to the coating layer 10 of the pressure-sensitive adhesive composition. At this time, the irradiation of ultraviolet rays, for example, may form a coating layer 10 of the pressure-sensitive adhesive composition between the two release film 20, it can be carried out on one side of the coating layer (10). Irradiated ultraviolet rays are absorbed at a predetermined rate in the course of progress along the thickness direction of the coating layer 10. Accordingly, the surface 10A to which ultraviolet rays are directly irradiated exhibits high elastic modulus and low peeling force due to sufficient curing, whereas the opposite surface 10B exhibits low elastic modulus and high peeling force due to relatively low degree of curing. .

Using the pressure-sensitive adhesive composition of the present invention as described above, adjust the type and content of the ultraviolet absorber, or the thickness of the coating layer (10 in FIG. 3), the wavelength or intensity of the irradiated ultraviolet rays, etc. that may be included in the composition as necessary. Thus, the pressure-sensitive adhesive of the desired aspect can be effectively implemented.

On the other hand, the irradiation of the ultraviolet ray, for example, can be carried out using a known means such as a high-pressure mercury lamp, an electrodeless lamp or a xenon lamp (xenon lamp). In addition, the ultraviolet irradiation conditions and the like are not particularly limited, and may be appropriately selected in consideration of the composition of the pressure-sensitive adhesive composition, thereby making it possible to effectively produce a cured product whose tensile modulus of elasticity changes in the thickness direction. In this case, the illuminance may be about 50 mW / cm ² to 2,000 mW / cm ² , and the light amount may be about 10 mJ / cm ² to 1,000 mJ / cm ² , but is not limited thereto.

In the present invention, in the production method, for the curing efficiency of the pressure-sensitive adhesive composition, the formation of the IPN structure, etc., a process such as heating, drying or aging may be performed in addition to the ultraviolet irradiation process.

The pressure-sensitive adhesive as described above, the gel content represented by the general formula 2 in the state of implementing the IPN structure is preferably 80% by weight or more, more preferably 90% by weight or more.

[Formula 2]

Gel content (% by weight) = B / A × 100

In Formula 2, A represents the mass of the pressure-sensitive adhesive embodying the IPN structure, B represents the dry mass of the insoluble fraction of the pressure-sensitive adhesive obtained after immersing the same pressure-sensitive adhesive in ethyl acetate at room temperature for 48 hours.

If the gel content is less than 80% by weight, there is a fear that the durability of the pressure-sensitive adhesive is lowered under high temperature and / or high humidity conditions. The upper limit of the gel content is not particularly limited. For example, the upper limit of the gel content may be appropriately adjusted in the range of 99% or less in consideration of stress relaxation characteristics of the pressure-sensitive adhesive.

The polarizing plate may further include a protective film attached to one surface of the polarizer, specifically, a surface opposite to the surface on which the pressure-sensitive adhesive layer is attached. As a protective film, For example, Cellulose-type films, such as a TAC film; Polyester film such as PET (poly (ethylene terephthalate)) film and the like; Polycarbonate film; Polyether sulfone-based film; Polyolefin films such as an acrylic film and / or a polyethylene film, a polypropylene film, a polyolefin film having a cyclo-based or norbornene structure, or an ethylene-propylene copolymer film may be used, but is not limited thereto. The protective film may be attached to the polarizer through, for example, the adhesive layer described above.

The polarizing plate may further include a release film attached to the lower portion of the pressure-sensitive adhesive layer. As a release film, the conventional structure of this field can be employ | adopted.

The polarizing plate may further include one or more functional layers selected from the group consisting of an antireflection layer, an antiglare layer, a retardation plate, a wide viewing angle compensation film, and a brightness enhancing film, as necessary.

An exemplary liquid crystal display of the present invention may include a liquid crystal panel and a polarizing plate according to the present invention attached to one side or both sides of the liquid crystal panel.

The kind of liquid crystal panel contained in a liquid crystal display device is not specifically limited. For example, a panel of a passive matrix type such as, but not limited to, a twisted nematic (TN) type, a super twisted nematic (STN) type, a ferrolectic (F) type, or a polymer dispersed (PD) type; Active matrix panels such as two-terminal or three-terminal; All known panels, such as an In Plane Switching (IPS) panel and a Vertical Alignment (VA) panel, can be applied.

In addition, other configurations constituting the liquid crystal display device, for example, types of upper and lower substrates (eg, color filter substrates or array substrates) are not particularly limited, and configurations known in the art may be employed without limitation. Can be.

One exemplary polarizing plate is lighter, has a thinner thickness, and is excellent in physical properties such as durability, water resistance, workability, durability, and light leakage inhibiting ability. In addition, one exemplary polarizing plate does not cause a problem of causing curl in the polarizing plate or the polarizer in the manufacturing process, and is excellent in heat resistance or thermal shock resistance.

1 is a cross-sectional view showing the structure of an exemplary polarizing plate.

2 is a cross-sectional view illustrating the pressure-sensitive adhesive layer as an example.

3 is a diagram illustrating an example of a process of forming an adhesive layer.

4 is a diagram schematically illustrating a method of evaluating curl characteristics.

1: polarizer

11: polarizer 10, 12: adhesive layer

13: adhesive layer

10A: first surface 10B: second surface

Hereinafter, the present invention will be described in more detail with reference to examples according to the present invention and comparative examples not according to the present invention, but the scope of the present invention is not limited to the following examples.

Preparation Example 1 Preparation of Acrylic Polymer

Nitrogen gas was refluxed, and 98 parts by weight of n-butyl acrylate (n-BA) and 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA) were added to a 1 L reactor equipped with a cooling device to facilitate temperature control. . Subsequently, 180 parts by weight of ethyl acetate (EAc) was added to the reactor as a solvent, and nitrogen gas was purged for 60 minutes to remove oxygen. Thereafter, the temperature was maintained at 67 ° C., 0.05 parts by weight of AIBN (azobisisobutyronitrile) as a reaction initiator was added, and the reaction was performed for 8 hours. After the reaction, an acrylic polymer (A) having a solid content concentration of 30% by weight, a weight average molecular weight of 1 million and a molecular weight distribution of 4.9 was prepared by diluting with ethyl acetate.

Preparation Example 2 Preparation of Adhesive Composition

As an acrylic monomer, an alicyclic epoxy compound (7-oxa-bicyclo [7-oxa-bicyclo [7-oxa-bicyclo [7-oxa-bicyclo [7-oxa-bicyclo [7-oxa-bicyclo [7-oxa-bicyclo [ 4,1,0] hetan-3-ylmethyl 7-oxa-bicyclo [4,1,0] heptane-3-carboxylate, 20% by weight of ceoxide, manufactured by Daicel Corporation) and glycidyl ether type epoxy compounds 20 parts by weight of (CHDMDG, 1,4-cyclohexane dimethanol diglycidyl ether) was added. Subsequently, 3 parts by weight of the radical polymerization initiator (CGI 819, (2,6-dimethoxybenzoyl)-(2,4,4-trimethylpentyl) phosphoryl)-(2,6-dimethoxyphenyl) methanone) and a cationic initiator (IHT-) were added to the mixture. PI 45, 50 wt% mixed triarylsulfonium hexafluorophosphate salt 50 wt% propylene carbonate) by weight of 3 parts by weight, to prepare an adhesive composition having a viscosity of about 10 cP at 25 ℃.

Example 1

Preparation of pressure-sensitive adhesive layer

100 parts by weight of the acrylic polymer (A), 3 parts by weight of a polyfunctional crosslinking agent (TDI isocyanate, Coronate L, manufactured by Nippon Polyurethane (Japan)), polyfunctional acrylate (trifunctional urethane acrylate, Aronix M-315, Dongwoo Commercially available) 100 parts by weight, photoinitiator (Irg 184, hydroxycyclohexylphenyl ketone, Swiss Ciba Specialty Chemical) 3 parts by weight, triazine-based ultraviolet absorber (Tinuvin 400, Swiss Ciba Specialty Chemical Co., Ltd.) 3 parts by weight and 0.1 weight part of silane coupling agents (M812, LG Chemical Co., Ltd.) which have a (beta) -cyanoacetyl group were mix | blended with a solvent so that solid content concentration might be 30 weight%, and the adhesive composition was manufactured. Subsequently, the prepared pressure-sensitive adhesive composition was coated on a release treated surface of a release treated PET (poly (ethyleneterephthalate)) film (thickness: 38 μm, MRF-38, manufactured by Mitsubishi Corporation) and then coated to have a predetermined thickness, and then in an oven at 110 ° C. Dry for 3 minutes. Thereafter, a release treatment surface of a release-treated PET film (thickness: 38 μm, MRF-38, manufactured by Mitsubishi Corporation) was further laminated on the dried coating layer to prepare a laminate having the structure shown in FIG. Ultraviolet rays were irradiated using a mercury lamp to form the pressure-sensitive adhesive layer 10 between the two release PET films 20. Hereinafter, for convenience of explanation, the surface of the side to which the ultraviolet-ray is irradiated from the adhesive layer 10 is called 1st surface 10A, and the opposite surface is called 2nd surface 10B.

<UV irradiation condition>

Roughness: 250 mW / cm ²

Light quantity: 300 mJ / cm ²

Preparation of Polarizer

A polyvinyl alcohol-based resin film was stretched, dyed with iodine, and treated with a boric acid aqueous solution to include one surface of a polarizer as an protective film including an acrylic film (phenoxy resin, polystyrene and polymethyl methacrylate). And a film prepared by extruding and stretching the mixture) were laminated with the adhesive composition prepared above. Subsequently, the prepared pressure-sensitive adhesive layer was laminated on the surface of the polyvinyl alcohol-based polarizer to which the protective film was not attached, thereby manufacturing a polarizing plate. Specifically, the adhesive composition is first applied to the polarizer so as to have a thickness of about 5 μm after curing, and after the first surface 10A of the pressure-sensitive adhesive layer is laminated on the coated surface, ultraviolet ray is cured by irradiation under the following conditions. A polarizing plate was prepared.

<UV irradiation condition>

UV irradiator: high pressure mercury lamp

Survey condition:

Illuminance: 800 mW / cm ²

Light quantity: 2000 mJ / cm ²

Examples 2-4 and Comparative Examples 1-4

A polarizing plate was manufactured in the same manner as in Example 1, except that the composition of the pressure-sensitive adhesive composition was changed as in Table 1 below.

Table 1

	Example				Comparative example
	One	2	3	4	One	2	3	4
Acrylic Copolymer	100	100	100	100	100	100	100	100
Crosslinking agent	3	3	3	3	3	3	3	3
MFA	100	120	150	120	120	120	120	-
Photoinitiator	3	3	3	3	3	3	3	-
UV absorbers	3	2	3	3	0.1	10	3	-
Silane coupling agent	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1
Thickness (㎛)	40	40	40	60	40	40	15	40
Content unit: parts by weight, MFA: trifunctional urethane acrylate (Aronix M-315, Dongwoo conventional), crosslinking agent: TDI isocyanate crosslinking agent (Coronate L, manufactured by Nippon Polyurethane), photoinitiator: Irg184: hydroxy cyclohexylphenyl Ketone (Switzerland Chivas Specialty Chemical), UV absorber: Triazine UV absorber (Tinuvin 400, Swiss Chivas Specialty Chemical), Silane coupling agent: M812: β-cyanoacetyl group-containing silane coupling agent (Korea LG Chemical)

Comparative Example 5

A thickness of 60 µm after drying the aqueous polyvinyl alcohol-based adhesive composition generally used for adhesion of the protective film as an adhesive for attaching the TAC film to the polarizer is used as a protective film instead of an acrylic film. After coating and using the water-based polyvinyl alcohol-based adhesive composition, the protective film was laminated and dried in an oven at 80 degrees for 5 minutes, and then the adhesive layer was laminated using the water-based polyvinyl alcohol-based adhesive composition. Except that a polarizing plate was prepared in the same manner as in Example 1.

<Property evaluation>

1. Evaluation of Tensile Modulus

In the present specification, the tensile modulus of the pressure-sensitive adhesive layer is measured by a stress-strain test method by tension in the manner defined in ASTM D638, or when it is difficult to directly measure the tensile modulus, the storage modulus is measured and the following conversion formula It is calculated | required in conversion by. Specifically, the pressure-sensitive adhesive layer prepared in Examples or Comparative Examples, the laminate (structure of the release PET film, pressure-sensitive adhesive layer and release PET film) of the structure shown in Figure 3 is 7 cm in length, width After cutting into dog bone type specimens having a size of 1 cm, both ends of the specimens were fixed with a tensile test jig, and the tensile modulus was measured. The measurement conditions of the tensile modulus are as follows.

<Measurement conditions of tensile modulus>

Measuring instrument: Universal Testing Machine (UTM)

Equipment Model: Zwick Roell Z010, Instron

Measuring conditions:

Load cell: 500 N

Tensile Speed: 3 mm / sec

<Measurement of storage modulus and conversion to tensile modulus>

The pressure-sensitive adhesive layer is cut to a size of 15 cm × 25 cm × 25 μm (width × length × thickness), and the cut pressure-sensitive adhesive layer is laminated in five layers. Subsequently, the laminated pressure-sensitive adhesive layer was cut into a circle having a diameter of 8 mm, and then left in the compressed state using glass to stand overnight, thereby improving the wetting at the interface between the layers, thereby resulting in bubbles generated during lamination. Prepare the sample by removing. Subsequently, the sample is placed on a parallel plate, the gap is adjusted, the zero point of Normal & Torque is set, the stabilization of the normal force is confirmed, and the following conditions are measured for the storage modulus. The tensile modulus is obtained by

Measuring instruments and measuring conditions

Measuring instrument: ARES-RDA, TA Instruments Inc. with forced convection oven

Measuring conditions:

geometry: 8 mm parallel plate

gap: around 1 mm

test type: dynamic strain frequency sweep

strain = 10.0 [%], temperature: 30 ℃

initial frequency: 0.4 rad / s, final frequency: 100 rad / s

<Conversion type>

E = 3G

In the conversion equation, E represents a tensile modulus, and G represents a storage modulus.

2. Peel force and re-peelability evaluation

Using the pressure-sensitive adhesive layer prepared in Example or Comparative Example, to prepare a polarizing plate in the same manner as in Example 1, to change the direction of the pressure-sensitive adhesive layer in accordance with the surface of the pressure-sensitive adhesive layer to measure the peel force to produce a polarizing plate. . That is, when the peeling force of the first surface is to be measured in the manufacturing process of the polarizing plate presented in Example 1, the second surface is attached to the polarizer side, and when the peeling force of the second surface is to be measured, the first surface is It attaches to the polarizer side and manufactures a polarizing plate. Thereafter, the polarizing plate was cut to a size of 25 mm x 100 mm (width x length) to prepare a specimen. Subsequently, the adhered release PET film on the pressure-sensitive adhesive layer is peeled off, and the surface of the pressure-sensitive adhesive layer is attached to the alkali-free glass using a 2 kg roller in accordance with JIS Z 0237. Subsequently, the alkali free glass with the pressure-sensitive adhesive layer was pressed for about 20 minutes in an autoclave (50 ° C., 0.5 atm), and stored for 25 hours at constant temperature and humidity conditions (23 ° C., 50% relative humidity). Thereafter, using a TA instrument (Texture Analyzer, manufactured by Stable Micro Systems Co., Ltd.), the peeling force is measured while the polarizing plate is peeled from the alkali free glass at a peel rate of 300 mm / min and a peel angle of 180 degrees. In addition, re-peelability is evaluated based on the following criteria.

<Releasability Evaluation Criteria>

(Circle): When peeling force measured one day after attachment is 800 N / 25 mm or less

(Triangle | delta): When peeling force measured 1 day after attachment is 1,000 N / 25mm or more

X: When the peeling force measured 1 day after attachment is 2,000 N / 25 mm or more

3. Durability Rating

Two specimens were prepared for each of Examples and Comparative Examples, prepared by cutting the polarizing plates prepared in Examples and Comparative Examples to a size of 90 mm × 170 mm (width × length). Subsequently, two prepared specimens were attached to both surfaces of a glass substrate (110 mm x 190 mm x 0.7 mm = width x length x thickness) so as to cross the optical absorption axis of each polarizing plate to prepare a sample. The pressure applied at the time of attachment was about 5 Kg / cm ² and the operation was performed in a clean room so that bubbles or foreign substances did not occur at the interface. After that, the heat-and-moisture resistance was evaluated by observing the occurrence of bubbles or peeling at the adhesive interface after leaving the sample for 1,000 hours at a temperature of 60 ° C. and a relative humidity of 90%. After leaving the sample for 1,000 hours under the temperature condition of 80 ℃, it was evaluated by observing the occurrence of bubbles or peeling at the adhesive interface. Samples prepared immediately before the measurement of heat-resistant or heat-resistant durability were left at room temperature for 24 hours and evaluated. Evaluation conditions are as follows.

Durability Evaluation Criteria

○: no bubbles and peeling

Δ: slight bubbles and / or peeling

×: large amount of bubbles and / or peeling

4. Water resistance evaluation

Samples were prepared by attaching specimens cut in a size of 90 mm × 170 mm (width × length) to the one side of a glass substrate (110 mm × 190 mm × 0.7 mm = width × length × thickness) prepared in Examples and Comparative Examples. . The pressure applied at the time of attachment was about 5 Kg / cm ^2, and the operation was performed in a clean room so that bubbles or foreign substances did not occur at the interface. Subsequently, the prepared sample was poured into water at a temperature of 60 ° C., left for 24 hours, and then taken out to observe whether bubbles or peeling occurred, and water resistance was evaluated based on the following criteria.

<Water resistance evaluation standard>

○: no bubbles and peeling

Δ: slight bubbles and / or peeling

×: large amount of bubbles and / or peeling

5. Light transmission uniformity evaluation

The polarizers prepared in Examples and Comparative Examples were attached to both sides of a 22-inch LCD monitor (manufactured by LG Philips LCD) with the optical absorption axes crossed with each other, and were subjected to constant temperature and humidity conditions (23 ° C., 50% relative humidity) for 24 hours. And then left for 200 hours at a temperature of 80 ° C. Then, the light transmittance was evaluated by the following reference | standard while irradiating light to the said monitor using a backlight in a dark room.

<Light transmission uniformity evaluation criteria>

(Double-circle): When the permeability of light transmittance is not judged visually in the four peripheral parts of a monitor.

(Circle): When the light transmittance nonuniformity is slightly observed by the four peripheral parts of a monitor.

(Triangle | delta): When the light transmittance nonuniformity is observed with the naked eye somewhat in the four peripheral parts of a monitor.

X: When a large amount of light-transmissive nonuniformity is observed by the naked eye in four peripheral parts of a monitor

6. Evaluation of weight average molecular weight and molecular weight distribution

The weight average molecular weight and molecular weight distribution of the acrylic polymer were measured under the following conditions using GPC. The measurement result was converted into the calibration curve using standard polystyrene of Agilent system.

<Weight average molecular weight measurement conditions>

Meter: Agilent GPC (Agilent 1200 series, USA)

Column: Connect 2 PL Mixed B

Column temperature: 40 ℃

Eluent: tetrahydrofuran

Flow rate: 1.0 mL / min

Concentration: ~ 2 mg / mL (100 μl injection)

7. Curl Characteristic Evaluation

Curl characteristics are laminated with a protective film and a polarizer cut to a size of 130 mm x 180 mm (horizontal (transverse direction (TD) x vertical (MD direction)) using an adhesive composition in the manufacturing process of the polarizing plate, and irradiated with ultraviolet rays or water-based When a polyvinyl alcohol-based adhesive is used, the curl generated in the TD direction during the drying process is measured and evaluated according to the following criteria. The measurement of curl in the above is carried out in the manner as shown in FIG. 4.

<Evaluation Criteria>

○: when the curl in the TD direction is less than 0.5 cm

(Triangle | delta): When the curl in a TD direction is 0.5 cm-2.0 cm

X: when the curl in the TD direction exceeds 2.0 cm

The measurement results are summarized in Table 2 below.

TABLE 2

	Example				Comparative example
	One	2	3	4	One	2	3	4	5
Tensile Modulus (25 ° C, MPa)	90	200	160	70	300	0.09	150	0.06	90
Peeling force (first surface) (gf / 25mm)	30	15	20	35	15	350	20	500	30
Peeling force (second surface) (gf / 25mm)	600	350	450	650	30	400	40	550	600
Re-peelability	○	○	○	○	○	△	○	△	○
Heat resistant and durable	○	○	○	○	×	×	×	×	○
Moisture resistance heat resistance	○	○	○	○	×	△	△	×	○
Water resistance	○	○	○	○	×	×	△	×	○
Light transmission uniformity	○	○	○	○	△	○	○	○	○
Curl properties	○	○	○	○	○	○	○	○	×

Claims (24)

1. Sequentially arranged polarizers; Active energy ray-curable adhesive layer; And an adhesive layer having a first surface and a second surface,

   A polarizing plate in which the difference between the peeling force on the alkali free glass of the first surface and the peeling force on the alkali free glass of the second surface satisfies the following general formula (1):

   [Formula 1]

   X ₂ -X ₁ 〉 50 gf / 25mm

   In said general formula 1, said X <_1> shows the peeling force with respect to the alkali free glass of a 1st surface, and said X <_2> shows the peeling force with respect to the alkali free glass of a 2nd surface.
2. The polarizing plate of claim 1, wherein the adhesive layer is directly attached to at least one surface of the polarizer, and the first surface of the adhesive layer is directly attached to the adhesive layer.
3. The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer of a single layer.
4. The polarizing plate according to claim 1, wherein the polarizer is a polyvinyl alcohol polarizer.
5. The polarizing plate of Claim 1 whose peeling force with respect to the alkali free glass of a 1st surface is 5 gf / 25mm-100 gf / 25mm.
6. The polarizing plate according to claim 1, wherein the peeling force on the alkali free glass of the second surface is 100 gf / 25mm to 1,000 gf / 25mm.
7. The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer is formed with a gradient of tensile modulus in the thickness direction from the first surface to the second surface direction.
8. The polarizing plate according to claim 7, wherein the pressure-sensitive adhesive layer is 0.1 MPa to 500 MPa of the average tensile modulus at 25 ° C.
9. The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer comprises a crosslinked structure comprising an acrylic polymer crosslinked by a multifunctional crosslinking agent and a crosslinked structure comprising a photopolymerizable compound.
10. The polarizing plate of claim 9, wherein the pressure-sensitive adhesive layer further comprises an ultraviolet absorber.
11. The polarizing plate of claim 1, wherein the adhesive layer comprises an adhesive composition comprising an epoxy compound and / or an acrylic monomer in a cured state.
12. The polarizing plate of claim 11, wherein the epoxy compound comprises an alicyclic epoxy compound and / or a glycidyl ether type epoxy compound.
13. The polarizing plate of claim 11, wherein the epoxy compound has a weight average molecular weight of 1000 to 5000.
14. The polarizing plate of claim 11, wherein the acrylic monomer comprises a hydrophilic acrylic monomer or a hydrophobic acrylic monomer.
15. The polarizing plate according to claim 14, wherein the hydrophilic acrylic monomer has a hydroxy group, a carboxyl group or an alkoxy group.
16. The polarizing plate of claim 11, wherein the adhesive composition further comprises 1 to 40 parts by weight of the reactive oligomer.
17. The polarizing plate according to claim 11, wherein the adhesive composition is a solventless type.
18. The polarizing plate of claim 11, wherein the adhesive composition has a viscosity at 25 ° C. of 5 cps to 1,000 cps.
19. The polarizing plate according to claim 1, further comprising a protective film attached to a surface opposite to the surface on which the pressure-sensitive adhesive layer of the polarizer is attached.
20. 20. The method of claim 19, wherein the protective film comprises a cellulose film; Polyester film; Polycarbonate film; Polyethersulfone films; Acrylic film; Or a polarizing plate which is a polyolefin film.
21. The polarizing plate of claim 1, further comprising at least one layer selected from the group consisting of an antireflection layer, an antiglare layer, a retardation plate, a wide viewing angle compensation film, and a brightness enhancement layer.
22. Liquid crystal panels; And a polarizing plate according to claim 1 attached to one side or both sides of the liquid crystal panel.
23. The liquid crystal display device according to claim 22, wherein the liquid crystal panel is attached to the second pressure sensitive adhesive layer.
24. The liquid crystal panel of claim 22, wherein the liquid crystal panel comprises: a passive matrix panel; Active matrix panel; A liquid crystal display device which is a transverse electric field panel or a vertical alignment panel.

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