KR102146537B1 - Pressure-sensitive adhesive - Google Patents

Abstract

The present application relates to a pressure-sensitive adhesive composition and a polarizing plate including the same, and provides a pressure-sensitive adhesive composition capable of selectively controlling a hard type and a soft type according to use, and having excellent holding power under severe conditions.

Description

Adhesive composition {PRESSURE-SENSITIVE ADHESIVE}

The present application relates to a pressure-sensitive adhesive composition and a polarizing plate including the same.

A liquid crystal display (LCD) is a display device that is used in various fields because it consumes less power and can be made thinner in a plane.

A liquid crystal display device includes: a liquid crystal panel including liquid crystals present between transparent substrates; And polarizing plates attached to both sides of the liquid crystal panel. The polarizing plate is attached by a pressure-sensitive adhesive, and at this time, productivity and environmental safety problems may occur due to the solvent present in the pressure-sensitive adhesive, and there is a problem that thermal wrinkles and coating lines are generated when the pressure-sensitive adhesive is thermally cured, and recently, flexible In a display or a curved display, there is a problem with respect to the holding power of the pressure-sensitive adhesive.

Accordingly, a solution to the above problem is required.

The present application relates to a pressure-sensitive adhesive for a polarizing plate, and provides a pressure-sensitive adhesive composition capable of selectively controlling a hard type and a soft type according to use, and having excellent holding power under severe conditions.

The present application relates to an adhesive composition. The pressure-sensitive adhesive composition may be applied to one surface of a polarizer. Specifically, the pressure-sensitive adhesive composition is attached to one surface of the polarizer in a cured state, and may be used for attaching a polarizing plate to a liquid crystal panel.

An exemplary pressure-sensitive adhesive composition may include a monomer component including a compound represented by the following Formula 1 or a polymer component having the monomer component as a polymerized unit. The pressure-sensitive adhesive composition may include a mixture of the monomer component and/or the polymer component. In the above, the monomer component or polymer component can form a partial polymer. Meanwhile, the mixture may be a photocurable composition, and the mixture may form a photocurable syrup. In the present application, by providing the composition, it is possible to suppress the occurrence of thermal wrinkles and coating streaks occurring during thermal curing, and to minimize productivity degradation and environmental safety problems due to solvents. In addition, the present application can maintain excellent retention of the pressure-sensitive adhesive under severe conditions by including the following Formula 1 as a monomer component or a polymerized unit.

[Formula 1]

In Formula 1, R ₁ is hydrogen or an alkyl group, X ₁ and X ₂ are each independently oxygen or a single bond, A is an alkylene group, an alkylidene group or a single bond, and R ₂ to R ₆ are each independently Hydrogen, an alkyl group or Q, R ₇ to R ₁₁ are each independently hydrogen or an alkyl group, and Q is a single bond, an alkylene group, an alkylidene group or a carbonyl group.

In Formula 1, that Q is connected to the center of the left benzene ring may mean that at least one of R ₂ to R ₆ is Q. For example, when R ₄ is Q, it may mean that Q is connected to the R ₄ position and two benzene rings are connected by Q.

In the specific example of the present application, the pressure-sensitive adhesive composition may be capable of primary crosslinking by light including any one wavelength in the UV region and secondary crosslinking by light having a wavelength lower than that of the first crosslinking. When the primary crosslinking and the secondary crosslinking proceed together, the crosslinking order is not particularly limited. During the secondary crosslinking, light may have a wavelength range of, for example, 260 nm to 330 nm, 268 nm to 329 nm, 277 nm to 316 nm, 283 nm to 309 nm, or 294 nm to 305 nm. In addition, light during the primary crosslinking may have a wavelength range of, for example, 330 nm to 380 nm, 331 nm to 372 nm, 342 nm to 369 nm, and 353 nm to 367 nm. In the present application, the pressure-sensitive adhesive by the first crosslinking may be used as a soft-type pressure-sensitive adhesive, and when the first and second crosslinking proceeds, the pressure-sensitive adhesive may be used as a hard type. Accordingly, the elastic modulus of the pressure-sensitive adhesive having only undergone primary crosslinking may have a lower elastic modulus than that of the pressure-sensitive adhesive that has progressed to the primary and secondary crosslinking. In the primary crosslinking, the ultraviolet range may be a conventional UV curable wavelength range. However, although the wavelength range in the secondary crosslinking is in the ultraviolet range, the degree of crosslinking in the conventional ultraviolet curable pressure-sensitive adhesive is significantly lowered at a wavelength of 330 nm or less. However, the present invention provides a composition capable of crosslinking the target even in light of a low wavelength of 330 nm or less. Accordingly, the pressure-sensitive adhesive composition of the present application may be used for a purpose by performing only the first crosslinking or performing the first and second crosslinking, if necessary.

In one example, the compound of Formula 1 includes benzophenone compounds such as benzophenone methacrylate (BPMA), 6-(4-benzoylphenoxy)hexyl (meth)acrylate or benzophenone acrylate. can do. I can.

In a specific example of the present application, the compound represented by Formula 1 is included in an amount of 0.01 to 10 parts by weight, 0.015 to 7 parts by weight, 0.1 to 6 parts by weight, or 0.15 to 3 parts by weight based on 100 parts by weight of the monomer component or polymer component. I can. In the present application, by adjusting the content ratio, when the pressure-sensitive adhesive composition is cured and applied to a polarizer, it is possible to implement adhesive retention even under severe conditions such as high temperature and high humidity conditions or physical conditions such as warpage.

In the present specification, the term "single bond" refers to a bond that connects an atom and an atom without a separate atom. For example, when A is a single bond in the above, the X ₁ atom and the X ₂ atom in Formula 1 may be directly connected. In this case, when the X ₂ atom is also a single bond, the X ₁ atom may be directly connected to the benzene ring. In addition, when Q is a single bond in Formula 1, the two benzene rings may be directly connected to each other.

In the present specification, the term "alkyl group" is 1 to 30 carbon atoms, 1 to 25 carbon atoms, 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, unless otherwise specified. It may mean an alkyl group of. The alkyl group may have a straight chain, branched chain or cyclic structure, and may be optionally substituted by one or more substituents.

In addition, the term ``alkylene group'' or ``alkylidene group'' in the present specification may mean an alkylene group or an alkylidene group having 1 to 12 carbon atoms, 4 to 10 carbon atoms, or 6 to 9 carbon atoms unless otherwise specified. . The alkylene group or alkylidene group may be linear, branched, or cyclic. In addition, the alkylene group or the alkylidene group may be optionally substituted by one or more substituents.

In the present specification, the term "aryl group", unless otherwise specified, may mean a monovalent residue derived from a compound containing benzene or a structure in which two or more benzenes are condensed or bonded, or a derivative thereof. have. The aryl group may be, for example, an aryl group having 6 to 22 carbon atoms, 6 to 16 carbon atoms, or 6 to 13 carbon atoms. For example, a phenyl group, a phenylethyl group, a phenylpropyl group, a benzyl group, a tolyl group, a xylyl group It may be a group (xylyl group) or a naphthyl group.

As a substituent that may be substituted with a specific functional group in the present specification, a halogen atom, a hydroxy group, a carboxyl group, a thiol group, an alkyl group, an alkoxy group, an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group , Acryloyloxy group, methacryloyloxy group, or aryl group may be exemplified, but is not limited thereto.

In one example of the present application, the monomer component may include a (meth)acrylic acid ester-based monomer. The (meth)acrylic acid ester-based monomer may exist as a monomer component in the pressure-sensitive adhesive composition or as a polymerized unit of a polymer. In one example, the pressure-sensitive adhesive composition comprises 50 to 99.9 parts by weight and 0.1 to 8 parts by weight of a (meth)acrylic acid ester-based monomer and a compound represented by Formula 1, respectively; 58 to 95 parts by weight and 0.15 to 5 parts by weight; Alternatively, it may be included in a weight ratio of 67 to 88 parts by weight and 0.18 to 2 parts by weight. The present application includes the weight ratio of Formula 1 and the (meth)acrylic acid ester-based monomer in the above range, and is applied to a polarizer to suppress contraction or expansion of the polarizer and suppress interlayer peeling, thereby providing a highly reliable polarizing plate. .

The term "part by weight" in the present specification may mean a weight ratio between each component.

In one example, the (meth)acrylic acid ester-based monomer may be an alkyl (meth)acrylate having a linear, branched or cyclic alkyl group. In the above, the alkyl (meth)acrylate may be an alkyl (meth)acrylate having an alkyl group having 1 to 14 carbon atoms in consideration of physical properties such as cohesion, glass transition temperature, and adhesion. Examples of such alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, t -Butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, Lauryl (meth) acrylate and tetradecyl (meth) acrylate, and the like, and one or two or more of them may be included in a form polymerized in a resin.

In one example, the monomer component may further include a compound represented by Formula 2 below.

[Formula 2]

In Formula 2, R ₁ is hydrogen or an alkyl group, X and Z are each independently an alkylene group or an alkylidene group, n is a number from 0 to 5, and R ₁₄ is an alkyl group or an aryl group.

Examples of Formula 2 may include 2-methoxyethyl acrylate or 2-(2-ethoxyethoxy)ethyl (meth)acrylate, but are not limited thereto. The present application may improve the durability reliability of the pressure-sensitive adhesive by adjusting the weight ratio of the compound of Formula 2 to the above range.

In one example, the monomer component may further include a compound represented by Formula 3 below.

[Formula 3]

In Formula 3, R ₁ is hydrogen or an alkyl group, A and T are each independently an alkylene group or an alkylidene group, and n is a number from 0 to 5.

In Formula 3, n may be more preferably a number of 0 to 3, and even more preferably 0 to 2. Examples of the compound of Formula 3 include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. , 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, or 2-hydroxypropylene glycol (meth)acrylate may be exemplified, but are not limited thereto.

In one example, the compound represented by Formula 2 may be included in 5 to 25 parts by weight, 9 to 23 parts by weight, 9.5 to 18 parts by weight, or 10 to 15 parts by weight based on 100 parts by weight of the monomer component or the polymer component. In addition, in one example, the compound represented by Formula 3 may be included in 5 to 25 parts by weight, 9 to 23 parts by weight, 9.5 to 18 parts by weight, or 10 to 15 parts by weight based on 100 parts by weight of the monomer component or the polymer component. have. In addition, the compound represented by Formula 2 and/or Formula 3 may be included in 5 to 50 parts by weight, 9 to 44 parts by weight, 11 to 38 parts by weight, or 17 to 27 parts by weight based on 100 parts by weight of the monomer component or the polymer component. have. In the present application, by adjusting the weight ratio of the compounds of Formulas 2 and 3 to the above range, it is possible to improve the retention power and durability against external stress.

In one example, the monomer component may further include a compound represented by Formula 4 below.

[Formula 4]

In Formula 4, R ₁ is hydrogen or an alkyl group, and U is a monovalent residue derived from an aliphatic saturated hydrocarbon cyclic compound.

In Formula 4, the monovalent residue may refer to an aliphatic saturated hydrocarbon cyclic compound, specifically a compound in which carbon atoms are bonded in a cyclic form, and may mean a monovalent residue derived from a compound other than an aromatic compound or a derivative of the compound. . The aliphatic saturated hydrocarbon cyclic compound may be an aliphatic saturated hydrocarbon cyclic compound having 3 to 20 carbon atoms, preferably 6 to 15 carbon atoms, and more preferably 8 to 12 carbon atoms. Examples of the monovalent residue include isobornyl, cyclohexyl, norbornanyl, norbornenyl, dicyclopentadienyl, ethynylcyclohexane, ethynylcyclohexene, or An ethynyl decahydronaphthalene group, etc. may be exemplified, and an isobornyl group may be used in one example, but is not limited thereto.

In one example, the compound represented by Formula 4 may be included in 1 to 15 parts by weight, 2 to 14 parts by weight, 3 to 13 parts by weight, or 4 to 12 parts by weight based on 100 parts by weight of the monomer component or the polymer component. If the ratio of the compound of Formula 4 in the monomer component is too low, the effect of securing durability may be insignificant, and if it is too high, the adhesiveness of the pressure-sensitive adhesive may be reduced, and thus the weight ratio can be controlled in consideration of this point.

The monomer or polymer component may be a component that forms the base of the pressure-sensitive adhesive after curing. The term “curing” may refer to a process in which the pressure-sensitive adhesive composition exhibits adhesive performance by a physical or chemical action or reaction of components included in the pressure-sensitive adhesive composition.

The monomer or polymer component may exist in various forms as long as it contains the components as described above and can be cured to exhibit adhesive properties.

In one example, if the composition is a thermosetting type, the monomer or polymer component may be an acrylic polymer having the monomer component as a polymerization unit. The acrylic polymer may be a crosslinkable acrylic polymer comprising a copolymerizable monomer that provides a crosslinkable functional group known in the adhesive resin field as a polymerization unit. In addition, in the case of the above, the pressure-sensitive adhesive composition may further include a multifunctional crosslinking agent capable of crosslinking the polymer. As the polyfunctional crosslinking agent, known crosslinking agents such as an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent can be used. In addition, the ratio of the crosslinking agent in the composition is not particularly limited, and may be appropriately adjusted in consideration of a desired cohesive force.

The pressure-sensitive adhesive composition may be a photocurable type. The term “photo-curing type pressure-sensitive adhesive composition” may mean a composition that can be converted into a pressure-sensitive adhesive by curing by irradiation of electromagnetic waves. The electromagnetic waves include microwaves, infrared (IR), ultraviolet (UV), X-rays, gamma rays, or alpha-particle beams, proton beams, neutron beams, and electron beams ( Particle beams such as electron beam) may be included, and ultraviolet rays or electron beams may be used.

When the pressure-sensitive adhesive composition is a photocurable type, the monomer or polymer component may include a photocurable oligomer and a reactive diluent monomer. Examples of the photocurable oligomer may include all oligomer components used in the preparation of a photocurable pressure-sensitive adhesive composition such as UV curable. For example, the oligomer may include a urethane acrylate such as a reaction product of a polyisocyanate and hydroxyalkyl (meth)acrylate having two or more isocyanate groups in the molecule; Ester-based acrylates such as polyester polyol and (meth)acrylic acid dehydration condensation reaction product; Ester urethane acrylate obtained by reacting an ester urethane resin which is a reaction product of a polyester polyol and a polyisocyanate with a hydroxyalkyl acrylate compound; Ether-based acrylates such as polyalkylene glycol di(meth)acrylate; Ether-based urethane acrylate obtained by reacting an ether-based urethane resin, which is a reaction product of a polyether polyol and a polyisocyanate, with a hydroxyalkyl (meth)acrylate; Or an epoxy acrylate such as an addition reaction product of an epoxy resin and (meth)acrylic acid, but is not limited thereto.

In one example, the pressure-sensitive adhesive composition of the present application may be a composition capable of simultaneously thermosetting and photocuring. In this case, a photoinitiator and a thermosetting multifunctional crosslinking agent may be included together. This application is capable of UV crosslinking by a polyfunctional acrylate and a photoinitiator and/or the above-described monomer component to be described later, and the present application includes a multifunctional crosslinking agent to be described later that can be simultaneously thermally cured to improve adhesion to an adherend. I can make it. In addition, in the present application, additional crosslinking may be performed by irradiating light in the low wavelength range described above.

As a reactive diluent monomer in this type of composition, a compound represented by Formulas 1 to 4 or (meth)acrylic acid may be used. As the reactive monomer, in addition to the above, as a monomer having a reactive functional group such as a (meth)acryloyl group, other monomers known in the art may also be used. Examples of the other monomers include alkyl (meth)acrylate; Aryl group-containing monomers such as benzyl (meth)acrylate or phenoxyethyl (meth)acrylate; Heterocyclic moiety-containing monomers such as tetrahydrofurfuryl (meth)acrylate or (meth)acryloyl morpholine; Alternatively, a multifunctional acrylate may be used, but the present invention is not limited thereto.

The pressure-sensitive adhesive composition may contain a polyfunctional acrylate together with the above-described components, if necessary. The polyfunctional acrylate may be preferably included, particularly when the monomer or polymer component is the above-described solvent-free type photocurable syrup, but is not limited thereto. As a kind of polyfunctional acrylate, for example, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol Di (meth) acrylate, neopentylglycol adipate (neopentylglycol adipate) di (meth) acrylate, hydroxyl puivalic acid (hydroxyl puivalic acid) neopentyl glycol di (meth) acrylate, dicyclopentanyl (dicyclopentanyl) di( Meth)acrylate, caprolactone modified dicyclopentenyl 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] Bifunctional acrylates such as fluorine; 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. of an isocyanate monomer and trimethylolpropane tri(meth)acrylate) A 6-functional acrylate such as a reactant may be used, but is not limited thereto.

The multifunctional acrylate may be included in an amount of 0.05 to 50 parts by weight, 0.06 to 35 parts by weight, 0.07 to 24 parts by weight, 0.08 to 18 parts by weight, or 0.09 to 9 parts by weight, based on 100 parts by weight of the monomer or polymer component. However, this may be changed in consideration of the process efficiency or physical properties of the adhesive.

In one example, the pressure-sensitive adhesive composition may further include a photoinitiator. The degree of polymerization can be controlled according to the amount of photoinitiator used. As the photoinitiator, any can be used as long as it can initiate a polymerization reaction through light irradiation or the like. For example, examples of the photoinitiator include alpha-hydroxyketone compounds (ex. IRGACURE 184, IRGACURE 500, IRGACURE 2959, DAROCUR 1173; Ciba Specialty Chemicals (manufactured)); Phenylglyoxylate-based compounds (ex. IRGACURE 754, DAROCUR MBF; Ciba Specialty Chemicals (manufactured)); Benzyl dimethyl ketal compounds (ex. IRGACURE 651; Ciba Specialty Chemicals (manufactured)); a-aminoketone-based compounds (ex. IRGACURE 369, IRGACURE 907, IRGACURE 1300; Ciba Specialty Chemicals (manufactured)); Monoacylphosphine compounds (MAPO) (ex. DAROCUR TPO; Ciba Specialty Chemicals (manufactured)); Bisacylphosphene compounds (BAPO) (ex. IRGACURE 819, IRGACURE 819DW; Ciba Specialty Chemicals (manufactured)); Phosphine oxide compounds (ex. IRGACURE 2100; Ciba Specialty Chemicals (manufactured)); Metallocene compounds (ex. IRGACURE 784; Ciba Specialty Chemicals (manufactured)); Iodonium salt (ex. IRGACURE 250; Ciba Specialty Chemicals (manufactured)); And a mixture of one or more of the above (ex.DAROCUR 4265, IRGACURE 2022, IRGACURE 1300, IRGACURE 2005, IRGACURE 2010, IRGACURE 2020; Ciba Specialty Chemicals (manufactured)), and the like. The pressure-sensitive adhesive composition may include one or more of the above, but is not limited thereto.

The photoinitiator may be included in the composition in an amount of 0.05 to 20 parts by weight based on 100 parts by weight of the above-described monomer or polymer component, but this may be changed in consideration of process efficiency or physical properties of the cured product.

In addition, in the present application, the pressure-sensitive adhesive composition may include a multifunctional crosslinking agent, and such a crosslinking agent improves the cohesiveness of the cured resin (adhesive agent) through reaction with a polar functional group included in the acrylic polymer, and imparts a crosslinking structure. It plays a role in controlling adhesive properties.

In one example, the multifunctional crosslinking agent may be at least one selected from the group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound, and the polymer of the present application may be crosslinked by the multifunctional crosslinking agent. In the present application, one or two or more crosslinking agents may be appropriately selected in consideration of the types of reactive functional groups contained in the polymer.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoboroone diisocyanate, tetramethylxylene diisocyanate or naphthalene diisocyanate, etc., but one of the above An addition reaction product of the above isocyanate compound and polyol may be used, and trimethylolpropane may be used as the polyol. In addition, the epoxy crosslinking agent is ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidyl ethylenediamine or glycerin diglycidyl One or more types of ethers, etc. may be used, and the aziridine crosslinking agent is N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4 ,4′-bis(1-aziridinecarboxamide), triethylene melamine, bisisoprotaloyl-1-(2-methylaziridine) or tri-1-aziridinylphosphine oxide, etc. may be exemplified. However, it is not limited thereto. In addition, as the metal chelate crosslinking agent, a compound in which a polyvalent metal such as aluminum, iron, zinc, tin, titanium, antimony, magnesium and/or vanadium is coordinated with acetyl acetone or ethyl acetoacetate may be exemplified. It is not limited.

In addition, in one example, the multifunctional crosslinking agent may be a mixture of aliphatic linear polyvalent NCO and alicyclic polyvalent NCO. For example, the aliphatic linear polyvalent NCO may be hexamethylene diisocyanate, and the alicyclic polyvalent NCO may be isoborone diisocyanate. The aliphatic linear polyvalent NCO and alicyclic polyvalent NCO may be mixed in a weight ratio of 6:4 to 9:1 to form a mixture, and in the mixture, NCO may be contained in an amount of 8 to 20% by weight. Meanwhile, in the present specification, the NCO may mean an isocyanate group.

The multifunctional crosslinking agent may be included in an amount of 0.01 to 10 parts by weight, 0.1 to 9 parts by weight, or 0.2 to 8 parts by weight based on 100 parts by weight of the monomer component or the polymer component.

This application also relates to a polarizing plate. The polarizing plate may include a polarizer and a pressure-sensitive adhesive layer formed on one surface of the polarizer and including the pressure-sensitive adhesive composition in a cured state.

The polarizer is a functional film or sheet capable of extracting only light vibrating in one direction from incident light while vibrating in various directions. As the polarizer, for example, a conventional polarizer such as a polyvinyl alcohol polarizer can be used. Such a polarizer may have a form in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. The polyvinyl alcohol-based resin constituting the polarizer can be obtained, for example, by gelling a polyvinyl acetate-based resin. Examples of the polyvinyl acetate-based resin include vinyl acetate homopolymers; And a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of the monomer copolymerizable with vinyl acetate include one or more mixtures of unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group, but are not limited thereto. The degree of gelation of the polyvinyl alcohol-based resin may be generally about 85 mol% to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin may be usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

The present application provides a pressure-sensitive adhesive composition capable of selectively controlling a hard type and a soft type according to the use, and having excellent holding power under severe conditions.

Hereinafter, the above-described contents will be described in more detail through Examples and Comparative Examples. However, the scope of the present application is not limited by the following examples.

Example One

70 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of isobornyl acrylate, 10 parts by weight of 4-hydroxybutyl acrylate, 10 parts by weight of 2-methoxyethyl acrylate and 0.2 parts by weight of benzophenone methacrylate A monomer mixture was prepared. An appropriate amount of EHPDC (EHPDC, di(2-ethylhexyl) peroxydicarbonate) was added as an initiator to the monomer mixture, followed by bulk polymerization to prepare a photocurable syrup. Based on 100 parts by weight of the monomer component, 0.3 parts by weight of a photoinitiator (2,4,6-trimethylbenzoyl diphenyl phosphoine, TPO), 0.1 parts by weight of 1,6-hexanediol diacrylate (HDDA), 0.2 parts by weight of a coupling agent, and A pressure-sensitive adhesive composition was prepared by mixing 0.1 parts by weight of a thermosetting agent (TKA-100). The prepared pressure-sensitive adhesive composition was applied to a silicone release-treated PET sheet, and the distance between the black light light source in the wavelength range of 365 nm and the layer of the applied pressure-sensitive adhesive composition was maintained at 15 cm. UV rays were irradiated for 5 minutes to prepare a pressure-sensitive adhesive layer having a thickness of 25 μm. A polarizing plate was prepared by attaching the pressure-sensitive adhesive layer to one side of a polyvinyl alcohol polarizer having a protective film formed on both sides.

Example 2

A pressure-sensitive adhesive layer and a polarizing plate were prepared in the same manner as in Example 1, except that the photoinitiator was changed to Irgacure 819.

Example 3

A pressure-sensitive adhesive layer and a polarizing plate were prepared in the same manner as in Example 1, except that the photoinitiator was changed to Irgacure 651.

Example 4

The pressure-sensitive adhesive layer of Example 1 was secondarily irradiated with ultraviolet rays at 2000 mJ/cm ² through a metal halide light source to prepare a pressure-sensitive adhesive layer and a polarizing plate.

Example 5

The pressure-sensitive adhesive layer of Example 2 was secondarily irradiated with ultraviolet rays at 2000 mJ/cm ² through a metal halide light source to prepare a pressure-sensitive adhesive layer and a polarizing plate.

Example 6

The pressure-sensitive adhesive layer of Example 3 was secondarily irradiated with ultraviolet rays at 2000 mJ/cm ² through a metal halide light source to prepare a pressure-sensitive adhesive layer and a polarizing plate.

Comparative example One

A monomer mixture was prepared by combining 99 parts by weight of n-butyl acrylate and 1 part by weight of 4-hydroxy butyl acrylate. An appropriate amount of EHPDC (EHPDC, di(2-ethylhexyl) peroxydicarbonate) was added as an initiator to the monomer mixture, followed by bulk polymerization to prepare a photocurable syrup. With respect to 100 parts by weight of the monomer component, 0.3 parts by weight of a photoinitiator (2,4,6-trimethylbenzoyl diphenyl phosphoine, TPO) and 0.1 parts by weight of 1,6-hexanediol diacrylate (HDDA) were mixed to prepare a pressure-sensitive adhesive composition. The prepared adhesive composition was applied to a PET sheet, and the thickness was increased by irradiating ultraviolet rays with the light source for about 5 minutes while maintaining the distance between the black light light source and the layer of the applied adhesive composition at 15 cm. A 25 μm pressure-sensitive adhesive layer was prepared. A polarizing plate was prepared by attaching the pressure-sensitive adhesive layer to one side of a polyvinyl alcohol polarizer having a protective film formed on both sides.

Comparative example 2

A thermosetting resin composition was prepared by adding a solvent with the same monomer composition as in Comparative Example 1. After adding 0.1 parts by weight of TKA-100 as a thermosetting agent based on 100 parts by weight of the resin composition, it was cured at 110° C. for 3 minutes to prepare a pressure-sensitive adhesive layer. A polarizing plate was prepared by attaching the pressure-sensitive adhesive layer to one side of a polyvinyl alcohol polarizer having a protective film formed on both sides.

Experimental example One - Back distance Measurement (Creep test)

When the pressure-sensitive adhesive layer of the polarizing plate according to the above Examples and Comparative Examples was attached to a glass plate with an adhesive area of 1 cm × 1 cm, and after 24 hours elapsed at room temperature, a load of 1 kg/f was applied at 25° C. for 1000 seconds, time Measure the pushed distance of the pressure-sensitive adhesive layer according to.

Pushed distance (mm) Example 1 1.13 Example 2 1.08 (dropped out at 925 seconds) Example 3 1.01 (dropped out at 850 seconds) Example 4 0.49 Example 5 0.49 Example 6 0.62 Comparative Example 1 Dropped out at 0 seconds Comparative Example 2 0.55

In Table 1, detachment means that all the adhesive areas are peeled off, and in Examples 2 and 3, the pushed distance before detachment was measured. Comparative Example 2 shows the push distance of the example level, but productivity decreases due to the solvent and environmental safety problems occurred, and thermal wrinkles and coating lines due to thermal curing were observed.

Claims (22)

A monomer component comprising a compound represented by the following formula (1) or a polymer component having the monomer component as a polymerization unit,
Primary crosslinking by light including any one wavelength in the UV region and secondary crosslinking by light having a wavelength lower than the wavelength at the time of the primary crosslinking are possible,
It is a solvent-free type,
The monomer component or the polymer component is a pressure-sensitive adhesive composition to form a partial polymer:
[Formula 1]

In Formula 1, R ₁ is hydrogen or an alkyl group, X ₁ and X ₂ are each independently oxygen or a single bond, A is an alkylene group, an alkylidene group or a single bond, and R ₂ to R ₆ are each independently Hydrogen, an alkyl group or Q, R ₇ to R ₁₁ are each independently hydrogen or an alkyl group, and Q is a single bond, an alkylene group, an alkylidene group or a carbonyl group. The pressure-sensitive adhesive composition of claim 1, wherein the light upon primary crosslinking has a wavelength range of 330 nm to 380 nm: The pressure-sensitive adhesive composition of claim 1, wherein the light during secondary crosslinking has a wavelength range of 260 nm to 330 nm: delete delete The pressure-sensitive adhesive composition of claim 1, wherein the compound represented by Formula 1 is contained in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of a monomer component or a polymer component. The pressure-sensitive adhesive composition of claim 1, wherein the monomer component further comprises a (meth)acrylic acid ester-based monomer. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth)acrylic acid ester-based monomer and the compound represented by Formula 1 are included in a weight ratio of 50 to 99.9 parts by weight and 0.1 to 8 parts by weight, respectively. The pressure-sensitive adhesive composition of claim 1, wherein the monomer component further comprises a compound represented by the following formula:
[Formula 2]

In Formula 2, R ₁ is hydrogen or an alkyl group, X and Z are each independently an alkylene group or an alkylidene group, n is a number from 0 to 5, and R ₁₄ is an alkyl group or an aryl group. The pressure-sensitive adhesive composition of claim 9, wherein the compound represented by Formula 2 is contained in an amount of 5 to 25 parts by weight based on 100 parts by weight of a monomer component or a polymer component. The pressure-sensitive adhesive composition of claim 1, wherein the monomer component further comprises a compound represented by the following formula (3):
[Formula 3]

In Formula 3, R ₁ is hydrogen or an alkyl group, A and T are each independently an alkylene group or an alkylidene group, and n is a number from 0 to 5. The pressure-sensitive adhesive composition of claim 11, wherein the compound represented by Formula 3 is contained in an amount of 5 to 25 parts by weight based on 100 parts by weight of a monomer component or a polymer component. The pressure-sensitive adhesive composition of claim 1, wherein the monomer component further comprises a compound represented by the following Formula 4:
[Formula 4]

In Formula 4, R ₁ is hydrogen or an alkyl group, and U is a monovalent residue derived from an aliphatic saturated hydrocarbon cyclic compound. The pressure-sensitive adhesive composition of claim 13, wherein the compound represented by Formula 4 is contained in an amount of 1 to 15 parts by weight based on 100 parts by weight of a monomer component or a polymer component. The pressure-sensitive adhesive composition according to claim 1, further comprising a multifunctional acrylate. The pressure-sensitive adhesive composition according to claim 15, wherein the polyfunctional acrylate is contained in an amount of 0.05 to 50 parts by weight based on 100 parts by weight of a monomer component or a polymer component. The pressure-sensitive adhesive composition according to claim 1, further comprising a photoinitiator. The pressure-sensitive adhesive composition according to claim 1, further comprising a multifunctional crosslinking agent. The pressure-sensitive adhesive composition of claim 18, wherein the multifunctional crosslinking agent is at least one selected from the group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound. The pressure-sensitive adhesive composition according to claim 18, wherein the polyfunctional crosslinking agent is a mixture of an aliphatic linear polyvalent isocyanate compound (NCO) and an alicyclic polyvalent isocyanate compound (NCO). The pressure-sensitive adhesive composition of claim 18, wherein the polyfunctional crosslinking agent is contained in an amount of 0.01 to 20 parts by weight based on 100 parts by weight of the monomer component or the polymer component. Polarizer; And a pressure-sensitive adhesive layer formed on one surface of the polarizer and comprising the pressure-sensitive adhesive composition according to claim 1 in a cured state.