KR101191113B1 - Pressure-sensitive adhesive composition, polarizer and liquid crystal display - Google Patents

Abstract

This invention relates to an adhesive composition, a polarizing plate, and a liquid crystal display device. The present invention can provide a pressure-sensitive adhesive having excellent durability in high temperature or high humidity conditions, and excellent in optical transparency, workability, re-peelability, and adhesion characteristics. In addition, the pressure-sensitive adhesive of the present invention can effectively suppress the light leakage phenomenon caused by the dimensional change of the polarizing plate or the like. Moreover, the adhesive composition of this invention does not contain a crosslinking agent component, and does not show the time-dependent change of the adhesive general physical properties like adhesive physical properties. In addition, in the present invention, it is possible to provide a pressure-sensitive adhesive excellent in various physical properties such as durability, workability and light leakage suppression performance under high temperature or high humidity conditions.

Pressure-sensitive adhesive composition, photopolymerizable group, acrylic resin, polyfunctional acrylate, photopolymerization initiator, polarizing plate, liquid crystal display device

Description

Pressure-sensitive adhesive composition, polarizer and liquid crystal display

This invention relates to an adhesive composition, a polarizing plate, and a liquid crystal display device.

The polarizing plate is an optical member included in a liquid crystal display (LCD). The polarizing plate includes an iodine-based compound or a dichroic polarizing material arranged in a predetermined direction, and has a multilayer structure in which a protective film (eg, triacetyl cellulose (TAC)) for protecting a polarizing film or an element is formed on both surfaces. In addition, the polarizing plate may further include additional films, such as a retardation plate, a wide viewing angle compensation plate, or a brightness enhancing film, in view of improving the function.

However, as described above, each film constituting the multilayer polarizing plate is made of a material having a different molecular structure and composition, thereby exhibiting different physical properties. Thus, especially under high temperature or high humidity conditions, there is a difference in shrinkage or expansion behavior of materials having a unidirectional molecular arrangement, which results in poor dimensional stability. Therefore, when the polarizing plate is fixed by the pressure-sensitive adhesive under a high temperature or high humidity conditions, the stress is concentrated in the protective film, birefringence is caused and light leakage occurs.

As a method for solving the above problems, there is known a technique for imparting stress relaxation property to the pressure-sensitive adhesive, and specifically, a method of designing the pressure-sensitive adhesive to be easy to deform with a large creep with respect to external stress is known. (ex. Korean Patent Publication No. 1998-079266, Japanese Patent Publication No. 2002-047468, etc.).

However, the said technique has the problem that the cutting property and workability of an adhesive are very inferior. Therefore, in the case of employing the above-described technique, defects such as pressure-sensitive adhesive squeezing or pressing occur in mass production of the polarizing plate, and thus the yield is greatly reduced.

On the other hand, as a concept contrary to the above technology, there is an attempt to minimize light leakage by designing the adhesive very hard (hard). For example, Japanese Patent Application Laid-Open Nos. 2007-197659 and 2007-212995 disclose a pressure-sensitive adhesive by adding a polyfunctional acrylate, an isocyanate curing agent and a photoinitiator to a carboxyl group-containing acrylic copolymer, and UV curing, Japanese Patent Laid-Open Publication No. 2007-212995 combines a hydroxy group-containing copolymer and a carboxyl group-containing copolymer in a predetermined ratio, and adds a polyfunctional acrylate, a polyfunctional isocyanate curing agent and a photoinitiator. To prepare a pressure-sensitive adhesive composition, UV-curing to produce a pressure-sensitive adhesive.

However, although the adhesive composition disclosed by the said technique contains all the crosslinking agents like an isocyanate compound, such a crosslinking agent remains after hardening, and deteriorates all the physical properties of the adhesive containing adhesive force with time.

An object of this invention is to provide an adhesive composition, a polarizing plate, and a liquid crystal display device.

The present invention is a means for solving the above problems, acrylic resin having a photopolymerizable group, the weight average molecular weight of 1 million or more; It provides a pressure-sensitive adhesive composition comprising a polyfunctional acrylate and a photopolymerization initiator, and satisfies the conditions of the following general formula (1).

[Formula 1]

In the general formula 1, Δ P represents the rate of change of the pressure-sensitive adhesive peeling force produced from the pressure-sensitive adhesive composition, P ₁ , after leaving the pressure-sensitive adhesive in the pressure-sensitive adhesive composition for 4 days after peeling of 300 min / min Peel force against the alkali-free glass measured under the conditions of the speed and the peeling angle of 180 degrees, P ₂ represents the peeling rate of 300 min / min and peeling of 180 degrees after leaving the pressure-sensitive adhesive with the pressure-sensitive adhesive composition for 15 days The peeling force with respect to the alkali free glass measured on condition of angle is shown.

The present invention is another means for solving the above problems, a polarizing film or a polarizing element; And a polarizing plate formed on one or both surfaces of the polarizing film or the polarizing element, the adhesive layer including a cured product of the pressure-sensitive adhesive composition according to the present invention.

As another means for solving the above problems, the present invention provides a liquid crystal display including a liquid crystal panel having a polarizing plate according to the present invention attached to one side or both sides.

The present invention can provide a pressure-sensitive adhesive having excellent durability in high temperature or high humidity conditions, and excellent in optical transparency, workability, re-peelability, and adhesion characteristics. In addition, the pressure-sensitive adhesive of the present invention can effectively suppress the light leakage phenomenon caused by the dimensional change of the polarizing plate or the like. Moreover, the adhesive composition of this invention does not contain a crosslinking agent component, and does not show the time-dependent change of the adhesive general physical properties like adhesive physical properties. In addition, in the present invention, it is possible to provide a pressure-sensitive adhesive excellent in various physical properties such as durability, workability and light leakage suppression performance under high temperature or high humidity conditions.

The present invention is an acrylic resin having a photopolymerizable group and having a weight average molecular weight of 1 million or more; It relates to a pressure-sensitive adhesive composition containing a polyfunctional acrylate and a photopolymerization initiator and satisfying the conditions of the following general formula (1).

[Formula 1]

In the general formula 1, Δ P represents the rate of change of the pressure-sensitive adhesive peeling force produced from the pressure-sensitive adhesive composition, P ₁ , after leaving the pressure-sensitive adhesive in the pressure-sensitive adhesive composition for 4 days after peeling of 300 min / min Peel force against the alkali-free glass measured under the conditions of the speed and the peeling angle of 180 degrees, P ₂ represents the peeling rate of 300 min / min and peeling of 180 degrees after leaving the pressure-sensitive adhesive with the pressure-sensitive adhesive composition for 15 days The peeling force with respect to the alkali free glass measured on condition of angle is shown.

Hereinafter, the pressure-sensitive adhesive composition according to the present invention will be described in detail.

In the pressure-sensitive adhesive composition of the present invention, the rate of change of the pressure-sensitive adhesive releasing force over time, specifically, the rate of change of the peeling force calculated by the general formula (1) is 20 (%) or less, preferably 10 (%) or less, More preferably, it may be 5 (%) or less. In the present invention, by providing the pressure-sensitive adhesive composition which does not change over time as described above, for example, when the pressure-sensitive adhesive is applied to optical members such as polarizing plates, excellent durability reliability can be maintained even for long-term use.

When the △ P is more than 20 in the present invention, there is, likely to be significantly reduced in accordance with the durability of lapse of the time at a high temperature or high humidity condition when the pressure-sensitive adhesive is applied to a polarizing plate.

On the other hand, the method for measuring the peel force applied to the general formula 1 in the present invention is not particularly limited, for example, it can be measured using a conventional tensile tester (ex. Texture analyzer), specifically described later Measurement can be made by the method given in Examples.

The acrylic resin used in the present invention may have a weight average molecular weight of 1 million or more. When the weight average molecular weight of acrylic resin in this invention is less than 1 million, there exists a possibility that durability of hardened | cured material may fall under high temperature or high humidity conditions. In the present invention, the upper limit of the weight average molecular weight of the acrylic resin is not particularly limited. However, if the weight average molecular weight is excessively increased, there is a possibility that problems such as deterioration of durability of the cured product or a decrease in coating properties may occur.

In the present invention, the acrylic resin includes a photopolymerizable group. The term "photopolymerizable group" used in the present invention means a functional group capable of causing a polymerization reaction by light irradiation or participating in a polymerization reaction by light irradiation, and representative examples thereof include ethylenically unsaturated groups (ex. Carbon carbon). Double bonds), but is not limited thereto. On the other hand, the term "light irradiation" used in the present invention refers to the irradiation of electromagnetic waves that can cause a polymerization reaction by affecting the photopolymerizable group contained in the acrylic resin or the photopolymerization initiator or polyfunctional acrylate described below, Electromagnetic waves can be microwave, infrared (IR), ultraviolet (UV), X-ray and γ-rays, as well as α-particle beams, proton beams, neutron beams and It is used generically to refer to a particle beam such as an electron beam.

The acrylic resin of the present invention may include the photopolymerizable group as described above, for example, in the side chain or the main chain, and preferably may be included in the side chain, but is not limited thereto.

For example, in this invention, an acrylic resin is a polymer of the monomer mixture containing a (meth) acrylic acid ester monomer and a functional group containing monomer (henceforth a "chain") .; And it may be a reactant of a photopolymerizable compound comprising a functional group and a photopolymerizable group capable of reacting with the functional group.

In the present invention, the kind of the (meth) acrylic acid ester monomer contained in the main chain of the acrylic resin is not particularly limited, and may be, for example, alkyl (meth) acrylate. In this case, if the alkyl group contained in the alkyl (meth) acrylate is too long, the cohesive force of the cured product may be lowered, and the glass transition temperature and the adhesion control may become difficult. Therefore, the (meth) having an alkyl group having 1 to 14 carbon atoms Preference is given to using acrylic ester monomers. Examples of 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-ethylbutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, And a mixture of one or more kinds of isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate and tetradecyl (meth) acrylate.

In the present invention, the (meth) acrylic acid ester monomer in the monomer mixture forming the main chain may be included in an amount of 90 parts by weight to 99.9 parts by weight based on the content of the functional group-containing monomer. If the content is less than 90 parts by weight, there is a fear that the initial adhesive force is lowered, if it exceeds 99.9 parts by weight, there is a fear that a problem in durability due to the decrease in cohesion force.

In the present invention, the functional group-containing monomer included in the monomer mixture forming the main chain imparts a functional group to the main chain. In the present invention, a part of the functional group imparted to the main chain as described above reacts with the functional group of the photopolymerizable compound described later, and does not react with the functional group of the photopolymerizable compound, and the remaining functional group is the adherend of the adhesive (ex. It may serve to improve the adhesion to the glass). Examples of such functional groups include a hydroxy group, a carboxyl group, an isocyanate group, an amino group, an epoxy group, and the like, and in the present invention, it is preferable to use a hydroxy group or a carboxyl group, but is not limited thereto.

In the present invention, the functional group-containing monomer is not particularly limited as long as it has the aforementioned functional group and unsaturated double bond in the molecule. For example, in the present invention, as the functional group-containing monomer, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxy Hexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate, (meth) acrylic acid, 2- ( A kind of meta) acryloyloxy acetic acid, 3- (meth) acryloyloxy propyl acid, 4- (meth) acryloyloxy butyl acid, fumaric acid, acrylic acid duplex, itaconic acid, maleic acid or maleic anhydride or Mixtures of two or more may be used, but are not limited thereto.

The content of the functional group-containing monomer in the monomer mixture of the present invention is not particularly limited depending on the physical properties of the cured product (ex. Adhesion to the substrate) and the amount of the photopolymerizable group to be introduced. In the present invention, for example, the monomer mixture may include 0.01 to 10 parts by weight of the functional group-containing monomer relative to the content of the (meth) acrylic acid ester monomer. When the content of the functional group-containing monomer is less than 0.01 part by weight, the amount of the photopolymerizable group that can be introduced into the main chain is insufficient, so that the cohesive force of the cured product may be lowered or the adhesion to the adherend may be lowered. There is a concern that a decrease in compatibility and / or flow characteristics may occur, or gelation may be caused in the manufacturing process to increase the viscosity of the resin and deteriorate the coating property.

In the present invention, the monomer mixture forming the main chain may further include a monomer represented by the following Chemical Formula 1 as necessary. Monomers represented by the following formula (1) may be added for the purpose of glass transition temperature control and other functional provision.

[Formula 1]

In Formula 1, R ₁ to R ₃ each independently represent hydrogen or alkyl, and R ₄ is cyano; Phenyl unsubstituted or substituted with alkyl; Acetyloxy; Or COR ₅ , wherein R ₅ represents amino or glycidyloxy unsubstituted or substituted with alkyl or alkoxyalkyl.

Alkyl or alkoxy in the definition of R ₁ to R _{5 in} the above formula means alkyl or alkoxy having 1 to 8 carbon atoms, preferably methyl, ethyl, methoxy, ethoxy, propoxy or butoxy.

Specific examples of the monomer represented by Formula 1 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 monomer of Formula 1 is included in the polymer of the present invention, the content thereof is preferably 20 parts by weight or less relative to the content of the (meth) acrylic acid ester monomer or the functional group-containing monomer included in the monomer mixture. When the content exceeds 20 parts by weight, there is a fear that the softness and / or peeling strength of the cured product is lowered.

The acrylic resin of the present invention is added to the main chain through a reaction with a functional group included in the main chain together with the main chain which is a polymer of the above-described monomer mixture, to add a photopolymerizable compound which provides a photopolymerizable group to the acrylic resin. It can be included as. The term "photopolymerizable compound" used in the present invention means a compound containing both a functional group and a photopolymerizable group capable of reacting with a functional group contained in an acrylic resin in a molecule. Such a photopolymerizable compound may be included in acrylic resin in the state in which the functional group contained reacts with the functional group contained in acrylic resin.

Specific types of photopolymerizable compounds that can be used in the present invention include 1 to 5, preferably 1 to 2, photopolymerizable groups per molecule, and have functional groups capable of reacting with functional groups contained in the main chain. As long as it does not restrict | limit. Examples of the functional group capable of reacting with the functional group of the main chain include an isocyanate group, an epoxy group, a silane group or a carboxyl group, but are not limited thereto. For example, when a hydroxyl group or a carboxyl group is introduced into the main chain, the functional group included in the compound may be an isocyanate group, an epoxy group or a chlorosilane group, or the like, and when the amino group or a substituted amino group is introduced into the main chain, the compound The functional group included in may be an isocyanate group or the like, and when the epoxy group is included in the main chain, the functional group included in the compound may be a carboxyl group.

Specific examples of the photopolymerizable compound which can be used in the present invention include 2-isocy anatoethyl (meth) acrylate, 1,1-bis (acryloyloxymethyl) ethyl isocyanate, and (meth) acryloyloxy ethyl Isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate or allyl isocyanate; Acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with 2-hydroxyethyl (meth) acrylate; Acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound, a polyol compound, and 2-hydroxyethyl (meth) acrylate; Glycidyl (meth) acrylate; (Meth) acrylic acid; Or 3-methacryloxypropyldimethylchlorosilane, or the like, or a heterogeneous compound, but is not limited thereto.

The content of the photopolymerizable compound in the present invention is not particularly limited to be selected according to the intended use, but is preferably adjusted to satisfy the conditions of the following general formula (2).

[Formula 2]

X = 0.01Y to 1Y

In General Formula 2, X represents the number of moles of the photopolymerizable compound, Y represents the number of moles of 1 part by weight of the functional group-containing monomer contained in the main chain.

In the present invention, when the value of X is less than 0.01 Y mol, the peeling force of the pressure-sensitive adhesive may be excessively increased, and the peeling process efficiency may be lowered. When it exceeds 1 Y-mol, the cohesive force of the pressure-sensitive adhesive is excessively increased, and the durability This may fall.

In the present invention, the substitution rate of the functional group included in the main chain by the photopolymerizable compound as described above may be less than 100%, preferably 90% or less, and more preferably 80% or less. In the present invention, when the substitution rate of the functional group is 100%, that is, the entire functional group contained in the main chain is replaced by reacting with the photopolymerizable compound, when the composition of the present invention is prepared with an adhesive, the adhesion to the substrate or glass may be lowered. There is. On the other hand, the lower limit of the substitution rate in the present invention is not particularly limited, for example, it can be controlled in the range of 5% or more, preferably 10% or more, more preferably 15% or more.

In the present invention, the method for producing an acrylic resin containing each component as described above is not particularly limited. In the present invention, for example, an acrylic resin is prepared by first preparing a polymer that forms a main chain, reacting a functional group introduced into the polymer (chain) with a functional group of a photopolymerizable compound, and introducing the photopolymerizable group into the polymer. It can manufacture.

In this case, the method for producing the main chain polymer is not particularly limited, and for example, it can be produced through a general polymerization method such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization or emulsion polymerization. In the present invention, it is particularly preferable to use a solution polymerization method. Specifically, the initiator may be mixed in a state in which each monomer is uniformly mixed, and solution polymerization may be performed at a polymerization temperature of 50 ° C to 140 ° C. Initiators which can be used at this time include azo polymerization initiators such as azobis isobutyronitrile or azobiscyclo hexane carbonitrile; And / or conventional initiators such as peroxides such as benzoyl peroxide or acetyl peroxide.

In addition, the method for reacting the main chain prepared as described above with the photopolymerizable compound is not particularly limited, and for example, the polymer and photopolymerizable compound forming the main chain may be used for 4 hours to 48 ° C. at a normal pressure of room temperature to 40 ° C. It can be prepared by reacting for a time. At this time, the reaction may be carried out using a catalyst such as organic tin in a solvent such as ethyl acetate.

The pressure-sensitive adhesive composition of the present invention contains a multifunctional acrylate. In the present invention, the multifunctional acrylate can, for example, impart a denser crosslinked structure to the cured product, and can act to improve durability and cohesiveness.

In the present invention, the kind of polyfunctional acrylate that can be used is not particularly limited. In the present invention, for example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylic Latex, neopentylglycol adipate di (meth) acrylate, hydroxyl puivalic acid neopentylglycol di (meth) acrylate, 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 dimethane (Meth) acrylate, neopentylglycol-modified trimethylpropane di (meth) acrylate, adamantane di (meth) acrylate or 9,9-bis [4- (2-acryloyloxyethoxy) Difunctional acrylates such as phenyl] fluorene 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 And 6 functional acrylates such as reactants, but are not limited thereto.

In the present invention, one or more kinds of the above-described multifunctional acrylates may be used in combination, or in particular, the use of an acrylate having a molecular weight of less than 1,000 and more than trifunctional is preferable in terms of more excellent durability, but not limited thereto. It doesn't happen.

In this invention, it is preferable to use the acrylate containing a ring structure among molecular structures as said polyfunctional acrylate. In this case, the ring structure included in the acrylate may be a carbocyclic structure or a heterocyclic structure; Or any of a monocyclic or polycyclic structure. More specifically, examples of the ring structure included in the multifunctional acrylate include a cycloalkyl structure having 3 to 12 carbon atoms, preferably 3 to 8 carbon atoms, such as cyclopentane, cyclohexane, or cycloheptane. The ring structure may be contained in one or more, preferably 1 to 5, more preferably 1 to 3, in the acrylate molecule. In addition, one or more hetero atoms such as O, S, or N may be contained in the cycloalkyl ring structure.

Specific examples of the polyfunctional acrylate including the ring structure as described above that can be used in the present invention include isocyanurate acrylates such as tris (meth) acryloxy ethyl isocyanurate and ring structures in the molecular structure. Urethane acrylate (ex. Isocyanate compound having a ring structure in the molecule (ex. Isoborone diisocyanate) and an acrylate compound containing a hydroxyl group (ex. Trimethylolpropane tri (meth) acrylate or pentaerythritol tri ( Meta) acrylate) reactants), etc., but is not limited thereto.

In the pressure-sensitive adhesive composition of the present invention, the polyfunctional acrylate as described above may be included in an amount of 5 parts by weight to 40 parts by weight based on 100 parts by weight of the acrylic resin. In the present invention, when the content of the polyfunctional acrylate is less than 5 parts by weight, durability may be reduced under high temperature or high humidity conditions, or the light leakage inhibitory effect may be reduced when applied to a polarizing plate or the like. Cohesion force rises too much and there exists a possibility that durability reliability may fall.

The adhesive composition of this invention also contains a photoinitiator. The kind of photoinitiator which can be used by this invention will not be restrict | limited in particular, if it can generate a radical by light irradiation and can start a polymerization reaction. Specific examples of the photopolymerization initiator that can be used in the present invention include a benzoin initiator, a hydroxy ketone initiator, an amino ketone initiator or a phosphine oxide initiator, and more specifically, benzoin and 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-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio ) Phenyl] -2-morpholino-propan-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-aminoanthraquinone, 2- Thioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid Esters, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and the like. However, it is not limited thereto. In the present invention, one or more kinds of the above can be used.

In the present invention, the photopolymerization initiator may be included in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the acrylic resin. In the present invention, when the content of the photopolymerization initiator is less than 0.1 part by weight, the polymerization or curing reaction may not be performed smoothly, and when it exceeds 5 parts by weight, physical properties such as durability and transparency may be lowered.

The pressure-sensitive adhesive composition of the present invention may further include a silane coupling agent. Such a coupling agent can improve the adhesiveness and adhesive stability between an adhesive and a glass substrate, and can improve heat resistance and moisture resistance. In addition, the coupling agent may act to improve adhesion reliability when the pressure-sensitive adhesive is left for a long time under high temperature or high humidity conditions. Examples of coupling agents that can be used in the present invention include γ-glycidoxypropyl triethoxy silane, γ-glycidoxypropyl trimethoxy silane, γ-glycidoxypropyl methyldiethoxy silane, γ-glycidoxy Propyl triethoxy 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, γ-acetoacetatepropyl triethoxy silane, (beta) -cyanoacetyl trimethoxy silane, (beta) -cyanoacetyl triethoxy silane, and acetoxy aceto trimethoxy silane can be mentioned, A mixture of 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 composition of the present invention, the silane coupling agent may be included in an amount of 0.01 to 5 parts by weight, preferably 0.01 to 1 part by weight based on 100 parts by weight of the acrylic resin. If the content of the coupling agent is less than 0.01 part by weight, the effect of increasing the adhesive strength may be insignificant. If it exceeds 5 parts by weight, the durability and reliability may be lowered.

The pressure-sensitive adhesive composition of the present invention may further include a tackifying resin from the viewpoint of adjusting the adhesion performance. The kind of such tackifying resin is not specifically limited, For example, (hydrogenated) hydrocarbon type resin, (hydrogenated) rosin resin, (hydrogenated) rosin ester resin, (hydrogenated) terpene resin, (hydrogenated) terpene phenol resin, One kind or a mixture of two or more kinds of a polymeric rosin resin or a polymeric rosin ester resin 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 resin. If the content is less than 1 part by weight, the effect of addition may be insignificant. If it exceeds 100 parts by weight, the compatibility and / or cohesion improvement effect may be lowered.

The pressure-sensitive adhesive composition of the present invention may also contain at least one additive selected from the group consisting of epoxy resins, crosslinkers, ultraviolet stabilizers, antioxidants, colorants, reinforcing agents, fillers, antifoaming agents, surfactants, and plasticizers. It may further include a.

The present invention also provides a polarizing film or polarizing element; And a polarizing plate formed on one or both surfaces of the polarizing film or the polarizing element and having an adhesive layer including a cured product of the pressure-sensitive adhesive composition according to the present invention.

The type of polarizing film or polarizing element included in the polarizing plate of the present invention is not particularly limited, and for example, a general material known in the art such as a polyvinyl alcohol-based polarizing film or an element may be employed without limitation.

The polarizing film or element is a functional film or sheet capable of extracting only light vibrating in one direction from incident light while vibrating in various directions. Such a polarizing film or element may be a form in which a dichroic dye is adsorbed and oriented in a polyvinyl alcohol-based resin film, for example. Polyvinyl alcohol-type resin which comprises a polarizing film or an element can be obtained by gelatinizing polyvinylacetate-type resin, for example. In this case, the polyvinylacetate resin which can be used may include not only a homopolymer of vinyl acetate but also a copolymer of vinyl acetate and other monomers copolymerizable with the above. Examples of the monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and a mixture of one or two or more kinds of acrylamides having an ammonium group, but are not limited thereto. no. The degree of gelation of the polyvinyl alcohol-based resin is usually 85 mol% to 100 mol%, 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 about 1,000 to 10,000, preferably about 1,500 to 5,000.

The above-mentioned polyvinyl alcohol-type resin is formed into a film, and can be used as a raw film of a polarizing film or an element. The method of forming a polyvinyl alcohol-type resin into a film is not specifically limited, The general method known in this field can be used. The thickness of the raw film formed into a polyvinyl alcohol-based resin is not particularly limited, and may be appropriately controlled within, for example, 1 µm to 150 µm. In consideration of ease of stretching and the like, the thickness of the master film can be controlled to 10 ㎛ or more.

The polarizing film or element is a step of stretching (ex. Uniaxial stretching) the polyvinyl alcohol-based resin film as described above, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye, adsorbing the dichroic dye, and dichroism. The dye-adsorbed polyvinyl alcohol-based resin film may be produced through a process of treating with a boric acid aqueous solution, and a process of washing with water after treating with a boric acid aqueous solution. As the dichroic dye, iodine or a dichroic organic dye may be used.

The polarizing plate of the present invention may further include a protective film formed on one side or both sides of the polarizing film or the polarizing element. The kind of protective film that can be included in the polarizing plate of the present invention is not particularly limited, and includes, for example, a cellulose film such as triacetyl cellulose; Polyester film such as polycarbonate film or polyethylene terephthalate film; Polyethersulfone-based films; And / or a protective film composed of a polyethylene film, a polypropylene film or a polyolefin film having a cyclo or norbornene structure, or a polyolefin film such as an ethylene propylene copolymer. At this time, the thickness of the protective film is also not particularly limited, and may be formed in a conventional thickness.

The polarizing plate of this invention is formed in the one or both surfaces of the said polarizing film or a polarizing element, and contains the adhesive layer containing the hardened | cured material of the adhesive composition which concerns on this invention. In the present invention, the "adhesive layer formed on one side or both sides of the polarizing film or the polarizing element" is a case where the adhesive layer is directly formed on the surface of the polarizing film or the element, as well as the above-mentioned protective film or each functional layer described later, It also includes the case where it is interposed between a polarizing film or an element, and an adhesion layer.

In the present invention, the method for forming the adhesive layer on the polarizing film or the polarizing element is not particularly limited, and for example, the adhesive composition (coating liquid) may be applied and cured by conventional means such as the bar coater or the adhesive composition. After apply | coating and hardening on the surface of a peelable base material once, the method etc. which transfer the formed adhesion layer to the surface of a polarizing film or an element can be used.

In the present invention, the formation process of the pressure-sensitive adhesive layer is preferably carried out after sufficiently removing the bubble-inducing components such as volatile components or reaction residues in the pressure-sensitive adhesive composition (coating liquid). As a result, the crosslinking density or molecular weight of the pressure-sensitive adhesive is too low, the elastic modulus is lowered, and bubbles present between the glass plate and the pressure-sensitive adhesive layer in a high temperature state become large, thereby preventing problems such as forming scatterers therein.

In addition, the method of curing the pressure-sensitive adhesive composition of the present invention at the time of manufacturing the polarizing plate is not particularly limited, for example, it is carried out through light irradiation, for example ultraviolet irradiation, etc., which can induce the activation of the photoinitiator contained in the composition. can do.

When applying the ultraviolet irradiation method in the present invention, the ultraviolet irradiation, for example, may be performed using a means such as a high pressure mercury lamp, an electrodeless lamp or a xenon lamp (xenon lamp). In addition, the irradiation amount in the ultraviolet curing method is not particularly limited as long as it is controlled to such a degree that sufficient curing is achieved without damaging the overall physical properties, for example, the illuminance is 50 mW / cm ² to 1,000 mW / cm ² , and the light amount is 50 mJ. It is preferred that it is / cm ² to 1,000 mJ / cm ² .

In the present invention, the pressure-sensitive adhesive layer prepared through the above process is preferably a gel content of 80% by weight or more, and preferably 90% by weight or more.

[Formula 3]

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

In the general formula (3), A represents the mass of the pressure-sensitive adhesive, B represents the dry mass of the insoluble fraction of the pressure-sensitive adhesive after 48 hours immersed in ethyl acetate at room temperature.

If the gel content is less than 80% by weight, the durability of the pressure-sensitive adhesive may be lowered under high temperature and / or high humidity conditions.

In the present invention, 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 the stress relaxation property of the adhesive.

The polarizing plate of the present invention may further include at least one functional layer selected from the group consisting of a protective layer, a reflective layer, an antiglare layer, a retardation plate, a wide viewing angle compensation film, and a brightness enhancing film.

The present invention also relates to a liquid crystal display device comprising a liquid crystal panel in which the polarizing plate according to the present invention described above is attached to one side or both sides.

The kind of liquid crystal panel contained in the liquid crystal display device of this invention as mentioned above is not specifically limited. In the present invention, for example, not limited to the type, F various passive matrix including TN (Twisted Neumatic) type, STN (Super Twisted Neumatic) type, F (ferroelectric) type, PD (polymer dispersed LCD) type, etc. system; Various active matrix schemes including two terminals and three terminals; Both known liquid crystal panels, including IPS mode panels and VA mode panels, can be applied. In addition, the kind and other manufacturing method of the other structure contained in the liquid crystal display device of this invention are not specifically limited, either, The general structure of this field can be employ | adopted and used without a restriction | limiting.

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 Resin (A-1)

98.5 parts by weight of n-butyl acrylate (n-BA) and 1.5 parts by weight of 2-hydroxyethyl acrylate (2-HEA) in a 1L reactor equipped with a refrigeration device for nitrogen gas reflux and easy temperature control The monomer mixture was added, followed by 120 parts by weight of ethyl acetate (EAc) as a solvent. Thereafter, after purging with nitrogen gas for 60 minutes to remove oxygen, the temperature was maintained at 60 ° C. Thereafter, the mixture was homogenized, and then 0.03 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 8 hours. After the reaction, the mixture was diluted with ethyl acetate to prepare an acrylic resin (A-1) having a solid content concentration of 15% by weight, a weight average molecular weight (M _w ) of 1.6 million, and a molecular weight distribution (PDI) of 4.8.

Preparation Example 2 Preparation of Acrylic Resin (A-2)

The weight average molecular weight (M _w ) was 400,000 in the same manner as in Preparation Example 1, except that n-dodecyl mercaptan (n-DDM) was added to the monomer mixture in an amount of 700 ppm as a molecular weight regulator. And the acrylic resin (A-2) whose molecular weight distribution (PDI) is 3.1 was manufactured.

Preparation Example 3 Preparation of Acrylic Resin (B-1)

In a 1L reactor in which nitrogen gas is refluxed and a cooling device is installed to facilitate temperature control, acrylic resin (A-1) and 2-isocyanatoethyl methacrylate (MOI; 2-isocyanatoethyl) prepared in Preparation Example 1 methacrylate) and DBTDL (dibutyl tindilaulate) were added. In the above description, the amount of 2-isocyanatoethyl methacrylate to be added is a molar number of 0.3Y when the molar number of 1 part by weight of the functional group-containing monomer (2-HEA) contained in the acrylic resin (A-1) is Y. It was controlled to add as much, the amount of DBTDL catalyst was controlled to be 0.5 wt% relative to the weight of the photopolymerizable compound (2-isocyanatoethyl methacrylate). Subsequently, the reaction is carried out for 4 hours or more at a temperature of 40 ° C. and at normal pressure, and 20% of the functional group (OH) introduced into the main chain (acrylic resin (A-1)) is substituted with an acrylic resin (B-1) substituted with a photopolymerizable group. Prepared. An acrylic resin (A) having a solid content concentration of about 40% and an unsaturated double bond introduced into the side chain was prepared (reaction conversion rate: 98% or more).

Preparation Examples 4 and 5. Preparation of Acrylic Resin (B-2 and B-3)

The same method as in Preparation Example 3 was applied, but the acrylic resins used, the number of moles of the photopolymerizable compound, and the substitution rate for the functional groups of the main chain were controlled as shown in Table 1 below to obtain acrylic resins (B-2 to B-4). Prepared.

[Table 1]

B-1 B-2 B-3 Acrylic resin A-1 A-1 A-2 X 0.3Y 0.12Y 0.3Y Substitution rate 20% 8% 20% X: number of moles of photopolymerizable compound
Y: mole number of 1 weight part of functional group containing monomer (2-HEA) contained in acrylic resin

Example 1.

Preparation of pressure-sensitive adhesive composition

15 parts by weight of polyfunctional acrylate (trisacryloxyethyl isocyanurate) to 100 parts by weight of acrylic resin (B-1), a photoinitiator (hydroxycyclohexylphenyl ketone, irgacure 184, Swiss Chivas Specialty Chemical (manufactured by )) 0.5 part by weight and 0.2 part by weight of the β-cyanoacetyl group-containing silane coupling agent (manufactured by LG Chem.) Were adjusted, and the solid content concentration was adjusted to 15% by weight to prepare a coating solution.

Preparation of Adhesion Polarizer

The prepared coating solution was coated on a polyethylene terephthalate (PET, MRF-38, Mitsubishi (manufactured)) film having a thickness of 38 µm released as a release sheet so as to have a thickness of 25 µm after drying, and then in an oven at 110 ° C. It was dried for 3 minutes. Subsequently, the dried film was stored in a constant temperature and humidity chamber (23 ° C., 55% RH) for about 1 day, and then a pressure-sensitive adhesive layer formed on the film on the WV coating layer of the polarizing plate coated with a WV (Wide View) liquid crystal layer on one side ( Coating liquid) was laminated. Then, the ultraviolet-ray of the following conditions was irradiated on the peeling film side, and the adhesive polarizing plate was produced.

UV treatment condition

UV irradiator: high pressure mercury lamp

Irradiation condition: illuminance = 600 mW / cm ² , light quantity = 150 mJ / cm ²

Example 2 and Comparative Examples 1 to 4

A pressure-sensitive adhesive 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 shown in Table 2 below.

[Table 2]

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Acrylic
Suzy Kinds B-1 B-2 A-1 B-3 B-1 B-1 usage 100 100 100 100 100 100 MFA usage 15 15 15 15 15 15 Photoinitiator Usage 0.5 0.5 0.5 0.5 0.5 0.5 Crosslinker Usage - - 2 - 2 0.5 SCA Usage 0.2 0.2 0.2 0.2 0.2 0.2 Usage unit: parts by weight
MFA: polyfunctional acrylate (trisacryloxyethyl isocyanurate)
Photoinitiator: Hydroxycyclohexylphenyl ketone (Swiss Ciba specialty chemical (product))
SCA: β-cyanoacetyl group-containing silane coupling agent (LG chemistry (product))
Crosslinking agent: Isocyanate type crosslinking agent (tolylene diisocyanate adduct of trimethylolpropane (TDI-1))

With respect to the pressure-sensitive adhesive polarizing plate of the prepared examples and comparative examples, the physical properties were evaluated by the method shown below, summarized in Table 3 below.

1. Evaluation of Adhesion (Peeling) and Re-peelability

The pressure-sensitive adhesive polarizing plates prepared in Examples and Comparative Examples were cut to a size of 25 mm x 100 mm (width x length) to prepare a sample, and after removing the peeling sheet, it was attached to an alkali free glass using a roller of 2 Kg. Thereafter, the mixture was compressed for about 20 minutes in an autoclave (50 ° C, 5 atmospheres), and stored for 24 hours in a constant temperature and humidity condition (23 ° C, 50% RH). Thereafter, using a physical analyzer (Texture Analyzer, UK Stable Microsystem), 4 days and 15 days were used as the next day after the pressure-sensitive adhesive was manufactured under conditions of a peel rate of 300 mm / min and a peel angle of 180 degrees, respectively. Adhesion (peel force) was measured at the elapsed time point, and re-peelability was evaluated based on the following criteria. On the other hand, apart from re-peelability evaluation, the next day after manufacture of the adhesive polarizing plate was made into 1 day, and the peeling force ( P ₁ ) immediately after 4 days passed and the peeling force ( P ₂ ) immediately after 15 days passed were measured. and, a time course change (reduction) (△ P) of the peel force in accordance with the general formula (1) was measured.

<Releasability Evaluation Criteria>

○: peeling force of the adhesive is 800 gf / 25 mm or less

(Triangle | delta): Peeling force of an adhesive is 1,000 gf / 25mm or more

X: Peeling force of the adhesive is 2,000 gf / 25 mm or more

2. Durability Reliability Assessment

Samples were prepared by cutting the adhesive polarizing plates of Examples and Comparative Examples to a size of 180 mm × 250 mm (width × length ), and the samples were attached to a 19 inch commercial panel using a laminator. Thereafter, compression treatment was performed for about 20 minutes in an autoclave (50 ° C. and 5 atmospheres), and stored in a constant temperature and humidity condition (23 ° C., 50% RH) for 24 hours to prepare a specimen. In order to evaluate the heat-resistant durability of the prepared specimens, the specimens were left for 500 hours at a temperature of 60 ° C. and a relative humidity of 90% RH, and then observed whether bubbles or peelings occurred. In addition, the heat resistance was evaluated by leaving the specimen at a temperature of 90 ° C. for 500 hours and then observing whether bubbles or peelings occurred. The specimens were subjected to evaluation after being left at room temperature for 24 hours immediately before evaluation, and the endurance reliability evaluation was evaluated at the time when 4 days and 15 days passed, respectively, with 1 day after the preparation of the pressure-sensitive adhesive.

Durability Reliability Evaluation Criteria

○: no bubbles and peeling

△: weakly bubble and / or peeling

X: A lot of bubble and / or peeling generate | occur | produces

The measurement results as described above are summarized in Table 3 below.

[Table 3]

Example Comparative example One 2 One 2 3 4 adhesiveness
(gf / 25mm) 4 days 300 320 320 800 470 270 15 days past 290 310 200 780 160 200 △ P 3.3 3.1 37.5 2.6 66.0 25.9 Re-peelability 4 days ○ ○ ○ ○ ○ ○ 15 days past ○ ○ ○ ○ ○ ○ Heat resistance
durability 4 days ○ ○ ○ × △ ○ 15 days past ○ ○ △ × × △ Heat resistance
durability 4 days ○ ○ ○ △ △ ○ 15 days past ○ ○ △ △ × △

As can be seen from the results of Table 3, in the results of the evaluation according to the present invention, the change over time (reduction) of the adhesive force is effectively suppressed, and also the durability reliability in the heat and moisture resistant conditions is excellently maintained. Could confirm. In contrast, in Comparative Examples 1, 3, and 4, in which the pressure-sensitive adhesive composition contains a crosslinking agent, the crosslinking agent remains after curing (aging or ultraviolet irradiation) of the pressure-sensitive adhesive and reacts with the functional group of the resin, and so on. It was confirmed that the peeling force was greatly reduced, and thus the durability was poor in heat and moisture resistant conditions. In addition, in the case of Comparative Example 2 having a low weight average molecular weight of the acrylic resin contained in the pressure-sensitive adhesive composition, the decrease in the adhesive force was prevented, but due to the decrease in the cohesive force, both the durability and reliability under the heat and moisture resistant conditions were confirmed to be greatly reduced. .

Claims (18)

Acrylic resin which has a photopolymerizable group and whose weight average molecular weight is 1 million or more; A polyfunctional acrylate and a photopolymerization initiator, Pressure-sensitive adhesive composition satisfying the conditions of the following general formula 1: [Formula 1]

In the general formula 1, Δ P represents the rate of change of the pressure-sensitive adhesive peeling force produced from the pressure-sensitive adhesive composition, P ₁ , after leaving the pressure-sensitive adhesive in the pressure-sensitive adhesive composition for 4 days after peeling of 300 min / min Peel force against the alkali-free glass measured under the conditions of the speed and the peeling angle of 180 degrees, P ₂ represents the peeling rate of 300 min / min and peeling of 180 degrees after leaving the pressure-sensitive adhesive with the pressure-sensitive adhesive composition for 15 days The peeling force with respect to the alkali free glass measured on condition of angle is shown. According to claim 1, △ P is 10 or less pressure-sensitive adhesive composition. The method of claim 1, wherein the acrylic resin is a polymer of a monomer mixture comprising a (meth) acrylic acid ester monomer and a functional group-containing monomer; And Pressure-sensitive adhesive composition which is a reactant of a photopolymerizable compound comprising a functional group and a photopolymerizable group capable of reacting with the functional group. The pressure-sensitive adhesive composition of claim 3, wherein the (meth) acrylic acid ester monomer is an alkyl (meth) acrylate. The pressure-sensitive adhesive composition according to claim 3, wherein the functional group-containing monomer comprises at least one functional group selected from the group consisting of a hydroxy group, a carboxyl group, an isocyanate group, an amino group and an epoxy group. The pressure-sensitive adhesive composition of claim 3, wherein the monomer mixture comprises 90 parts by weight to 99.99 parts by weight of the (meth) acrylic acid ester monomer and 0.01 parts by weight to 10 parts by weight of the functional group-containing monomer. The photopolymerizable compound of claim 3, wherein the photopolymerizable compound is 2-isocyanatoethyl (meth) acrylate, 1,1-bis (acryloyloxymethyl) ethyl isocyanate, (meth) acryloyloxy ethyl isocyanate, meta- Isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, acryloyl monoisocyanate compound, glycidyl (meth) acrylate, (meth) acrylic acid and 3-methacryloxypropyldimethylchlorosilane One or more pressure-sensitive adhesive composition selected from the group consisting of. The pressure-sensitive adhesive composition of claim 3, which satisfies the conditions of the following general formula 2: [Formula 2] X = 0.01Y to 1Y In the general formula 2, X represents the number of moles of the photopolymerizable compound, Y represents the number of moles of 1 part by weight of the functional group-containing monomer. The pressure-sensitive adhesive composition of claim 1, wherein the multifunctional acrylate includes a ring structure in a molecular structure. The pressure-sensitive adhesive composition of claim 9, wherein the ring structure is a cycloalkyl ring having 3 to 12 carbon atoms. The pressure-sensitive adhesive composition of claim 1, comprising 5 parts by weight to 40 parts by weight of polyfunctional acrylate based on 100 parts by weight of acrylic resin. The pressure-sensitive adhesive composition of claim 1, wherein the photopolymerization initiator is a benzoin compound, a hydroxy ketone compound, an amino ketone compound, or a phosphine oxide compound. The pressure-sensitive adhesive composition of claim 1, wherein the photopolymerization initiator is included in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the acrylic resin. The pressure-sensitive adhesive composition of claim 1, further comprising a silane coupling agent. Polarizing film or polarizing element; And a pressure-sensitive adhesive layer formed on one side or both sides of the polarizing film or the polarizing element, and including a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 14. The polarizing plate of claim 15, further comprising a protective film formed on one or both surfaces of the polarizing film or the polarizing element. The polarizing plate of claim 15, wherein the adhesive layer has a gel content of 80 wt% or more represented by the following general formula (3): [Formula 3] Gel content = B / A × 100 In the general formula (3), A represents the mass of the pressure-sensitive adhesive, B represents the dry mass of the insoluble content of the pressure-sensitive adhesive after immersing the pressure-sensitive adhesive for 48 hours with ethyl acetate at room temperature. A liquid crystal display device comprising a liquid crystal panel having a polarizing plate according to claim 15 attached to one or both sides.