KR101266219B1 - 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. In the present invention, by lowering the weight average molecular weight of the crosslinkable acrylic polymer that reacts with the multifunctional crosslinking agent to implement a crosslinked structure, it provides excellent stress relaxation property to the pressure-sensitive adhesive, thereby generating light leakage due to the dimensional change of the polarizing plate It can be effectively suppressed. In addition, the present invention, by implementing an interpenetrating polymer network structure in the pressure-sensitive adhesive, to prevent the durability degradation due to the low weight average molecular weight of the acrylic polymer, to provide a pressure-sensitive adhesive excellent in various physical properties such as adhesive properties, re-peelability and workability can do.

Adhesive composition, weight average molecular weight, IPN, polarizing plate, liquid crystal display device

Description

Pressure-sensitive adhesive composition, polarizer and liquid crystal display

The present 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, under high temperature and / or high humidity conditions, dimensional stability is lacking due to the difference in shrinkage or expansion behavior of materials with unidirectional molecular arrangements. Therefore, when the polarizing plate is fixed by an adhesive, stress is concentrated on the TAC layer or the like under high temperature or high humidity conditions, thereby causing birefringence and light leakage phenomenon.

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, in the above technology, there is a problem that the tackiness of the pressure-sensitive adhesive is very poor. If the property of the pressure-sensitive adhesive agent is deteriorated, the pressure-sensitive adhesive tends to be pinched or pressed during the mass production of the polarizing plate, resulting in a problem that 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, the pressure-sensitive adhesive disclosed in the above technique, depending on the storage modulus (G '), the initial adhesive strength is greatly reduced, thereby resulting in low durability or high light leakage caused by high temperature or high humidity.

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

The present invention, a means for solving the above problems, a weight average molecular weight of more than 500,000, less than 1 million crosslinkable acrylic polymer; And it provides a pressure-sensitive adhesive composition comprising a multi-functional cross-linking agent, to implement an interpenetrating polymer network in the curing state.

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

As another means for solving the above problems, the present invention provides a liquid crystal display device comprising a liquid crystal panel in which the polarizing plate of the present invention is attached to one side or both sides.

In the present invention, by lowering the weight average molecular weight of the crosslinkable acrylic polymer that reacts with the multifunctional crosslinking agent to implement a crosslinked structure, giving excellent pressure relaxation property to the pressure-sensitive adhesive, thereby generating light leakage according to the dimensional change of the polarizing plate Can be effectively suppressed. In addition, in the present invention, by implementing an interpenetrating polymer network structure in the pressure-sensitive adhesive, to prevent the durability degradation due to the low weight average molecular weight of the acrylic polymer, the pressure-sensitive adhesive with excellent physical properties such as adhesive properties, re-peelability and workability Can provide.

The present invention is a crosslinkable acrylic polymer having a weight average molecular weight of more than 500,000, less than 1 million; And multifunctional crosslinking agents,

An adhesive composition which implements an interpenetrating polymer network (hereinafter sometimes referred to as "IPN") in a cured state.

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

The pressure-sensitive adhesive composition of the present invention contains a crosslinkable acrylic polymer having a weight average molecular weight of more than 500,000 and less than 1 million. The weight average molecular weight of an acryl-type polymer means polystyrene conversion value measured by gel permeation chromatography (GPC) above.

The term "crosslinkable acrylic polymer" used in the present invention means an acrylic polymer containing a functional group capable of reacting with a polyfunctional crosslinking agent described later in a molecule.

In the present invention, if the weight average molecular weight of the crosslinkable acrylic polymer is 500,000 or less, the durability of the pressure-sensitive adhesive may be lowered due to the decrease in cohesion. This may be caused.

The specific composition of the crosslinkable acrylic polymer used in the present invention is not particularly limited as long as it has a weight average molecular weight in the above-described range and includes a crosslinkable functional group. In the present invention, for example, as a crosslinkable acrylic polymer, 80 parts by weight to 99.8 parts by weight of (meth) acrylic acid ester monomer; And 0.02 to 20 parts by weight of the crosslinkable monomer.

The specific kind of the (meth) acrylic acid ester monomer contained in the monomer mixture in the above is not particularly limited, and may be, for example, alkyl (meth) acrylate. In this case, when the alkyl group contained in the alkyl (meth) acrylate is too long, the cohesion force of the pressure-sensitive adhesive may be lowered, and the glass transition temperature (T _g ) or the adhesion may become difficult to be controlled. Preference is given to using alkyl (meth) acrylates having 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-ethylhexyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, Isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate and tetradecyl (meth) acrylate, and the present invention may use one or more of the above. . The monomer mixture of the present invention may include the (meth) acrylic acid ester monomer as described above in an amount of 80 parts by weight to 99.8 parts by weight based on the content of the crosslinkable functional group. If the content is less than 80 parts by weight, there is a fear that the initial adhesive strength of the pressure-sensitive adhesive is lowered, if it exceeds 99.8 parts by weight, there is a fear that durability problems occur due to the decrease in cohesive force.

The monomer mixture of the present invention includes a crosslinkable monomer. The term "crosslinkable monomer" refers to a monomer capable of imparting a crosslinkable functional group capable of reacting with a polyfunctional crosslinking agent to an acrylic polymer, and controlling the durability, adhesiveness, cohesion, and the like of the pressure-sensitive adhesive depending on the amount of use thereof. can do.

Examples of the crosslinkable monomer that can be used in the present invention include, but are not limited to, hydroxy group-containing monomers, carboxyl group-containing monomers and nitrogen-containing monomers. Specific examples of the hydroxy group-containing monomers 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, and the like. Examples of the carboxyl group-containing monomers Is (meth) acrylic acid, 2- (meth) acryloyloxy acetic acid, 3- (meth) acryloyloxy propyl acid, 4- (meth) acryloyloxy butyl acid, acrylic acid duplex, itaconic acid, maleic acid And maleic anhydride. Examples of the nitrogen-containing monomer include (meth) acrylamide, N-vinyl pyrrolidone, or N-vinyl caprolactam, but are not limited thereto. In the present invention, a mixture of one or more of the above can be used.

In the monomer mixture of the present invention, the crosslinkable monomer may be included in an amount of 0.02 parts by weight to 20 parts by weight based on the content of the (meth) acrylic acid ester monomer. If the content is less than 0.02 parts by weight, the durability of the pressure-sensitive adhesive may be lowered. If it exceeds 20 parts by weight, the adhesion and / or peeling force may be lowered.

In the present invention, the monomer mixture constituting the crosslinkable acrylic polymer may further include a compound represented by the following Chemical Formula 1 as necessary. The compound of Chemical Formula 1 may be added for the purpose of controlling the glass transition temperature of the pressure-sensitive adhesive and providing other functionalities.

[Formula 1]

Wherein each of R ₁ to R ₃ independently represents hydrogen or alkyl, R ₄ is cyano; Phenyl unsubstituted or substituted with alkyl; Acetyloxy; Or COR < _{5 &} gt ;, wherein R < ₅ > represents amino or glycidyloxy substituted or unsubstituted with alkyl or alkoxyalkyl.

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

Specific examples of the monomer of 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 methylstyrene; 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 mixture of the present invention includes the compound of Formula 1, the content thereof may be 20 parts by weight or less relative to the content of the (meth) acrylic acid ester monomer. When the content exceeds 20 parts by weight, there is a fear that the flexibility and / or peeling force of the pressure-sensitive adhesive is lowered.

The method for producing the crosslinkable acrylic polymer using the monomer mixture in the present invention is not particularly limited, and may be prepared using, for example, a general polymerization method such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization or emulsion polymerization. have. In the present invention, in particular, a solution polymerization method may be used, and solution polymerization is preferably performed at a polymerization temperature of 50 ° C. to 140 ° C. by adding an initiator in a state where each monomer is uniformly mixed. Examples of initiators that can be used in this process include azo initiators such as azobisisobutyronitrile or azobiscyclohexane carbonitrile; And / or conventional initiators such as peroxides such as benzoyl peroxide or acetyl peroxide, and the like, but may be used one or a mixture of two or more thereof, but is not limited thereto.

That is, the pressure-sensitive adhesive composition of the present invention includes a multifunctional crosslinking agent capable of reacting with the aforementioned crosslinkable acrylic polymer to implement a crosslinked structure.

The kind of specific crosslinking agent that can be used in the present invention is not particularly limited, and for example, a general crosslinking agent such as an isocyanate compound, an epoxy compound, an aziridine compound and a metal chelate compound may be used. Specific examples of the isocyanate compound include tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, tetramethylxylene diisocyanate, naphthalene diisocyanate and polyols of any of the above. one or more selected from the group consisting of reactants with (ex. trimethylol propane); Specific examples of the epoxy compound include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N, N, N ', N'-tetraglycidyl ethylenediamine and glycerin diglycidyl At least one selected from the group consisting of ethers; Specific examples of aziridine compounds include N, N'-toluene-2,4-bis (1-aziridinecarboxamide), N, N'-diphenylmethane-4,4'-bis (1-aziridinecar Radiation amide), triethylene melamine, bisisoprotaloyl-1- (2-methylaziridine) and tri-1-aziridinylphosphineoxide, but are not limited thereto. no. Further, specific examples of the metal chelate compound include compounds in which polyvalent metals such as aluminum, iron, zinc, tin, titanium, antimony, magnesium, and / or vanadium are coordinated with acetyl acetone, ethyl acetoacetate, and the like. However, this is not limiting.

In the pressure-sensitive adhesive composition of the present invention, the crosslinking agent may be included in an amount of 0.01 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the crosslinkable acrylic polymer. In the present invention, when the content of the crosslinking agent is less than 0.01 part by weight, the cohesive force of the pressure-sensitive adhesive may be lowered. When the content of the crosslinking agent is more than 10 parts by weight, the durability may be lowered, such as interlayer peeling or lifting.

The pressure-sensitive adhesive composition of the present invention implements an IPN structure in a cured state. As used herein, the term "cured state of the adhesive composition" means a state in which the composition of the present invention is produced in the form of a pressure-sensitive adhesive through a light irradiation and / or heating step. The term "light irradiation" used in the present invention refers to irradiation of electromagnetic waves that can cause a polymerization reaction by affecting a photoinitiator or a polyfunctional acrylate and the like, wherein the electromagnetic waves are microwaves, infrared rays (IR), ultraviolet rays ( UV, X-rays and γ-rays, as well as particle beams such as α-particle beam (α-particle beam), proton beam (neuton beam), neutron beam (electron beam) and electron beam (electron beam) Used.

In addition, the term "IPN structure" is embodied by other components together with the crosslinked structure (hereinafter sometimes referred to as "first crosslinked structure") by the pressure-sensitive adhesive reacted with the crosslinkable acrylic polymer and the polyfunctional crosslinking agent described above. It means the state which two or more crosslinked structures are implemented simultaneously in an adhesive including the additional crosslinked structure (Hereinafter, it may be called a "2nd crosslinked structure."). As such, the pressure-sensitive adhesive composition, re-peelability, and the like, by constructing the pressure-sensitive adhesive composition so that the pressure-sensitive adhesive realizes the IPN structure, while preventing the degradation of durability that may be caused by using an acrylic polymer having a relatively low weight average molecular weight. And it can implement an adhesive excellent in various physical properties such as workability.

The pressure-sensitive adhesive composition of the present invention may further include a non-crosslinkable acrylic polymer. The term "non-crosslinkable acrylic polymer" used in the present invention means an acrylic polymer which does not contain a functional group capable of reacting with a multifunctional crosslinking agent in a molecule. In the present invention, the non-crosslinked polymer regulates the gel fraction of the crosslinkable polymer forming a gel by the polyfunctional crosslinking agent, enters the crosslinking network (IPN) of the pressure sensitive adhesive, and plasticizes the pressure sensitive adhesive. It can increase the elasticity and flexibility, and suppress the light leakage phenomenon.

In the present invention, the non-crosslinkable acrylic polymer may have a weight average molecular weight of more than 500,000 and less than 1 million. In the present invention, by controlling the weight average molecular weight of the non-crosslinkable acrylic polymer in the above range, it is possible to maintain excellent cohesion, durability, and stress relaxation of the pressure-sensitive adhesive at the same time.

On the other hand, the specific composition of the non-crosslinkable acrylic polymer that can be used in the present invention is not particularly limited as long as it has a weight average molecular weight in the above-described range.

The composition of the non-crosslinkable polymer that can be used in the present invention is not particularly limited. In this invention, the polymer of the monomer mixture containing a (meth) acrylic acid ester monomer can be used as said non-crosslinkable acrylic polymer, for example. In this case, the specific kind of the (meth) acrylic acid ester monomer that can be used is not particularly limited, and for example, the same monomer as described in the above-mentioned crosslinkable acrylic polymer can be used. In addition, the monomer mixture constituting the non-crosslinkable acrylic polymer may include additional monomer components, such as the compound of Formula 1, unless the crosslinkable monomer is included.

When the non-crosslinkable polymer is included in the pressure-sensitive adhesive composition of the present invention, the weight ratio (crosslinkable acrylic polymer: non-crosslinkable acrylic polymer) with the crosslinkable acrylic polymer may be, for example, more than 10: 0 and 5: 5 or less. . That is, in the present invention, the non-crosslinkable acrylic polymer may be included in an amount of 100 parts by weight or less based on 100 parts by weight of the crosslinkable acrylic polymer. When the content of the non-crosslinkable acrylic polymer in the present invention exceeds 100 parts by weight, there is a fear that durability reliability under high temperature or high humidity conditions may decrease due to the decrease in cohesive force of the pressure-sensitive adhesive.

The pressure-sensitive adhesive composition of the present invention may further include a multifunctional acrylate. In this invention, the said polyfunctional acrylate can give a crosslinked structure to an adhesive by the polymerization reaction by the action of the photoinitiator mentioned later.

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.

Especially in this invention, it is preferable to use acrylate containing a cyclic structure among molecular structures as a 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. Specifically, examples of the ring structure included in the multifunctional acrylate include a cycloalkyl ring structure having 3 to 12 carbon atoms, preferably 3 to 8 carbon atoms, such as cyclopentane, cyclohexane, or cycloheptane. One or more ring structures may be included in the acrylate, preferably 1 to 5, more preferably 1 to 3, and one or more hetero atoms such as O, S or N may also be included.

As a specific example of the polyfunctional acrylate containing a ring structure as mentioned above which can be used by this invention, the monomer which has isocyanurate structures, such as a tris (meth) acryloxy ethyl isocyanurate, isocyanurate Of modified urethane acrylates (e.g., isocyanate compounds having a ring structure in a molecule (ex. Isoborone diisocyanate) and acrylate compounds (e.g. trimethylolpropane tri (meth) acrylate or pentaerythritol tri (meth) acrylate) Reactants, etc.), but the present invention is not limited thereto.

In the pressure-sensitive adhesive composition of the present invention, the multifunctional acrylate may be included in an amount of more than 5 parts by weight and less than 15 parts by weight based on 100 parts by weight of the aforementioned crosslinkable acrylic polymer. In the present invention, if the content of the multifunctional acrylate is 5 parts by weight or less or 15 parts by weight or more, the durability of the pressure-sensitive adhesive may be lowered.

The pressure-sensitive adhesive composition of the present invention may further include a photoinitiator. The said photoinitiator can advance the polymerization reaction of polyfunctional acrylate by light irradiation, and can provide a crosslinked structure in an adhesive.

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 the polymerization reaction of polyfunctional acrylate. Specific examples of photoinitiators that can be used in the present invention include benzoin, hydroxy ketone, amino ketone or phosphine oxide, and more specifically, benzoin, benzoin methyl ether, and 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-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylamino Benzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthio Ton, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid ester, oligo [2-hydroxy-2- Methyl-1- [4- (1-methylvinyl) phenyl] propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide, and the like, but are not limited thereto. In the present invention, one or more of the above can be used.

In the present invention, the photoinitiator is contained in an amount of 0.01 to 10 parts by weight, preferably 0.01 to 5 parts by weight, or 0.2 to 20 parts by weight with respect to 100 parts by weight of the multifunctional acrylate based on 100 parts by weight of the crosslinkable acrylic polymer. May be included. In the present invention, when the content of the photoinitiator is too small, the polymerization or curing reaction may not be performed smoothly, when too large, there is a fear that physical properties such as durability, transparency and the like.

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 include γ-glycidoxypropyl triethoxy silane, γ-glycidoxypropyl trimethoxy silane, γ-glycidoxypropyl methyldiethoxy silane, γ-glycidoxypropyl trie Methoxy silane, 3-mercaptopropyl trimethoxy silane, vinyl trimethoxysilane, vinyltriethoxy silane, γ-methacryloxypropyl trimethoxy silane, γ-methacryloxy propyl triethoxy silane, γ-amino Propyl trimethoxy silane, γ-aminopropyl triethoxy silane, 3-isocyanato propyl triethoxy silane, γ-acetoacetate propyl trimethoxysilane, γ-acetoacetate propyl triethoxy silane, β-sia Noacetyl trimethoxy silane, (beta) -cyanoacetyl triethoxy silane, and acetoxy aceto trimethoxy silane are mentioned, One type or a mixture of two or more of these 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; And a pressure-sensitive adhesive layer formed on one or both surfaces of the polarizing film and including a cured product of the pressure-sensitive adhesive composition according to the present invention.

The kind of polarizing film used by this invention is not specifically limited, The general kind known in this field can be employ | adopted. For example, the polarizing film may include a polarizer; And a protective film formed on one or both surfaces of the polarizer.

The kind of polarizer contained in the polarizing plate of this invention is not specifically limited, For example, the general kind known in this field, such as a polyvinyl alcohol-type polarizer, can be employ | adopted without a restriction | limiting.

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. Such a polarizer may be, for example, a form in which a dichroic dye is adsorbed in a polyvinyl alcohol-based resin film. Polyvinyl alcohol-type resin which comprises a polarizer can be obtained by gelatinizing polyvinylacetate-type resin, for example. In this case, the polyvinylacetate-based resin that 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 monomers such as unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group, or a mixture of two or more thereof. 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 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 polarizer. 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 polarizer is a step of stretching (ex. Uniaxial stretching) the polyvinyl alcohol resin film as described above, a step of dyeing the polyvinyl alcohol resin film with a dichroic dye, adsorbing the dichroic dye, and a dichroic dye adsorbed. The polyvinyl alcohol-based resin film can 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 dichroic organic dyes may be used.

The polarizing film of the present invention may further include a protective film formed on one side or both sides of the polarizer. 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.

In the present invention, the method of forming the adhesive layer on the polarizing film is not particularly limited, and for example, the adhesive composition (coating liquid) is applied and cured by conventional means such as the bar coater, or the adhesive composition is once peelable. After apply | coating and hardening on the surface of a base material, the method etc. which transfer the formed adhesion layer to the polarizing film surface 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). Accordingly, the crosslinking density or molecular weight of the pressure-sensitive adhesive is too low, the elastic modulus is lowered, and the bubbles existing between the glass plate and the pressure-sensitive adhesive layer in the high temperature state is increased, it is possible to prevent the problem of forming a scattering body 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 2]

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

In Formula 2, 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 stress relaxation characteristics of the pressure-sensitive 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 Crosslinkable Acrylic Polymer (A)

A monomer mixture comprising 98 parts by weight of n-butyl acrylate (n-BA) and 2 parts by weight of hydroxyethyl methacrylate (HEMA) was added to a 1 L reactor equipped with a refrigeration apparatus for reflux of nitrogen gas and for easy temperature control. Administered. Subsequently, 120 parts by weight of ethyl acetate (EAc) was added as a solvent, and nitrogen gas was purged for 60 minutes to remove oxygen. Thereafter, the temperature of the reactor was maintained at 60 ° C., and 0.03 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, followed by reaction for 8 hours, and a crosslinkable acrylic polymer having a weight average molecular weight of about 700,000 ( A) was prepared.

Preparation Examples 2 to 8. Preparation of Crosslinkable and Noncrosslinkable Acrylic Polymer

A crosslinkable and non-crosslinkable acrylic polymer was prepared in the manner according to Preparation Example 1, except that the monomer composition and the weight average molecular weight of the prepared polymer were changed as shown in Tables 1 and 2 below.

[Table 1]

Copolymer (A) Copolymer (B) Copolymer (C) Copolymer (D) Monomer composition
(Parts by weight) n-BA / HEMA
(98/2) n-BA
(100) n-BA / AA
(97/3) n-BA / HEMA
(99/1) Mw (only) 70 70 70 150 n-BA: n-butyl acrylate
HEMA: 2-hydroxyethyl methacrylate
AA: Acrylic acid
M _w : weight average molecular weight

[Table 2]

Copolymer (E) Copolymer (F) Copolymer (G) Copolymer (H) Monomer composition
(Parts by weight) n-BA
(100) n-BA / HEMA
(99/1) n-BA
(100) n-BA / HEMA
(98/2) Mw (only) 150 120 120 40 n-BA: n-butyl acrylate
HEMA: 2-hydroxyethyl methacrylate
AA: Acrylic acid
M _w : weight average molecular weight

Example 1.

Preparation of pressure-sensitive adhesive composition

12 parts by weight of tris (acryloxyethyl) isocyanurate (molecular weight: 423, trifunctional, aronix M-315) with respect to 100 parts by weight of the crosslinkable acrylic polymer (A), 1-hydroxycyclohexyl phenyl as a photoinitiator 1.59 parts by weight of a ketone (Irg184, manufactured by Ciba) and 0.01 parts by weight of trimethylol-modified tolylene diisocyanate (coronate L) as a crosslinking agent were blended to prepare an adhesive composition.

Preparation of Adhesion Polarizer

The prepared pressure-sensitive adhesive composition was coated on a 38 μm thick PET film (MRF-38, manufactured by Mitsubishi Corporation) after release treatment as a release sheet, and then coated to a thickness of 25 μm, and dried in an oven at 110 ° C. for 3 minutes. Subsequently, the dried coating layer was stored in a constant temperature and humidity chamber (23 ° C., 55% RH) for about 24 hours, and then the adhesive layer was laminated on the WV coating layer of the polarizing plate coated with a WV (Wide View) liquid crystal layer on one side. . Subsequently, the ultraviolet irradiation process was performed under the following conditions, and the adhesive polarizing plate was produced.

<UV irradiation condition>

UV irradiator: high pressure mercury lamp

Irradiation condition: Illuminance = 600 mW / cm ² , Light quantity = 150 mJ / cm ²

Examples 2-4 and Comparative Examples 1-6.

A pressure-sensitive adhesive polarizing plate was manufactured by the method according to Example 1, except that the composition of the pressure-sensitive adhesive composition was changed as shown in Tables 3 and 4 below.

[Table 3]

Example One 2 3 4 Crosslinkable
Copolymer Kinds A A C C Weight portion 100 100 100 100 Non-crosslinking
Copolymer Kinds - B - B Weight portion - 25 - 25 Crosslinkable: Non-crosslinkable 10: 0 8: 2 10: 0 8: 2 MFA
Kinds M315 M315 M315 M315 Weight portion 12 12 12 12 Photoinitiator
Kinds Irg184 Irg184 Irg184 Irg184 Weight portion 1.59 1.59 1.59 1.59 Cross-linking agent
Kinds Coronate l Coronate l Coronate l Coronate l Weight portion 0.01 0.07 0.04 0.07 M315: tris (acryloxyethyl) isocyanurate (molecular weight: 423, trifunctional type)
Irg184: 1-hydroxycyclohexyl phenyl ketone (Irg184, manufactured by Ciba)
Crosslinking agent: trimethylol modified tolylene diisocyanate (coronate L)
Crosslinkable: noncrosslinkable = weight ratio of crosslinkable acrylic polymer and noncrosslinkable acrylic polymer

[Table 4]

Comparative example One 2 3 4 5 6 Crosslinkable
Copolymer Kinds D D F F A H Weight portion 100 100 100 100 100 100 Non-crosslinking
Copolymer Kinds E - G - - - Weight portion 400 - 400 - - - Crosslinkable: Non-crosslinkable 2: 8 10: 0 2: 8 10: 0 10: 0 10: 0 MFA
Kinds M315 - M315 - - M315 Weight portion 12 - 12 - - 12 Photoinitiator
Kinds Irg184 - Irg184 - - Irg184 Weight portion 1.59 - 1.59 - - 1.59 Cross-linking agent
Kinds Coronate l Coronate l Coronate l Coronate l Coronate l Coronate l Weight portion 0.04 0.04 0.04 0.04 0.04 0.04 M315: tris (acryloxyethyl) isocyanurate (molecular weight: 423, trifunctional type)
Irg184: 1-hydroxycyclohexyl phenyl ketone (Irg184, manufactured by Ciba)
Crosslinking agent: trimethylol modified tolylene diisocyanate (coronate L)
Crosslinkable: noncrosslinkable = weight ratio of crosslinkable acrylic polymer and noncrosslinkable acrylic polymer

The physical properties of the adhesive polarizers prepared in Examples and Comparative Examples were measured by the following methods, and the results are summarized in Tables 5 and 6 and described.

1. Evaluation of the bending characteristics of the liquid crystal panel

The pressure-sensitive adhesive polarizers prepared in Examples and Comparative Examples were attached to both surfaces of a conventional liquid crystal panel with a vertical polarizer. Then, the liquid crystal panel with a polarizing plate was left to stand in an 80 degreeC oven for 72 hours, and after removing it from the oven, the curvature degree was measured along four corners of a liquid crystal panel within 5 minutes, and the curvature characteristic was evaluated according to the following reference | standard.

<Evaluation Criteria>

⊙: No bending of liquid crystal panel

○: slight warpage occurs in the liquid crystal panel

△: warpage occurs slightly in the liquid crystal panel

×: warpage greatly occurs in the liquid crystal panel

2. Durability Reliability Assessment

Samples were prepared by cutting the adhesive polarizers prepared in Examples and Comparative Examples to a size of 90 mm × 170 mm, and attaching the glass substrate (110 mm × 190 mm × 0.7 mm) to both sides with the optical absorption axis crossed. . At this time, the applied pressure was about 5 Kg / cm ² , the operation was performed in a clean room so as not to generate bubbles or foreign matter. In order to understand the heat and moisture resistance of the prepared sample, the sample was left for 1,000 hours at a temperature of 60 ° C. and a relative humidity of 90%, and observed for bubbles or peeling. In addition, the heat resistance was observed for the occurrence of bubbles or peeling also after standing for 1,000 hours at a temperature of 80 ℃. The state of the specimen was evaluated after being left at room temperature for 24 hours immediately before evaluation. The evaluation criteria for reliability are as follows.

<Evaluation Criteria>

○: no bubbles or peeling

B: Bubbles or peeling phenomenon occurred slightly

×: large amount of bubbles and peeling phenomenon

3. Light transmission uniformity evaluation

Light transmittance uniformity was measured using the same specimen as the endurance reliability evaluation. The specimen was irradiated with backlight to observe whether there was a part of light leaking from the dark room. Specifically, the light transmittance uniformity was evaluated by attaching the adhesive polarizer (200 mm × 200 mm) to the glass substrate (210 mm × 210 mm × 0.7 mm) at 90 degrees to the optical absorption axis and attaching them to both sides. Evaluation criteria of light transmittance uniformity are as follows.

<Evaluation Criteria>

○: Non-uniformity of light transmittance is difficult to judge with the naked eye

△: slight light transmittance nonuniformity

X: The light non-uniformity is abundant.

[Table 5]

Example One 2 3 4 Flexural characteristics ○ ⊙ ○ ⊙ Endurance
responsibility Heat resistant condition ○ ○ ○ ○ Moisture-resistant heat condition ○ ○ ○ ○ Light transmission uniformity ○ ○ ○ ○

TABLE 6

Comparative example One 2 3 4 5 6 Flexural characteristics × △ × △ ⊙ ⊙ Endurance
responsibility Heat resistant condition ○ ○ ○ △ × × Moisture-resistant heat condition ○ ○ ○ △ × × Light transmission uniformity × △ △ △ × ×

As can be seen from the results of Tables 5 and 6, in Examples 1 to 4 according to the present invention, all the bending properties, durability and light transmittance uniformity of the pressure-sensitive adhesive were excellently maintained.

However, in the case of Comparative Examples 1 and 3 using the acrylic polymer having a weight average molecular weight of 1 million or more, it was confirmed that the warpage property and the light transmittance uniformity were greatly reduced even though the IPN structure was implemented in the pressure-sensitive adhesive. Moreover, in the comparative example 6 using the polymer whose weight average molecular weight is 500,000 or less, durability and light transmittance uniformity fell significantly.

In addition, in the case of using the polymer having a weight average molecular weight of 1 million or more, and Comparative Examples 2 and 4 in which the IPN is not implemented in the pressure-sensitive adhesive, it is confirmed that one or more of the bending properties, durability and light leakage inhibiting property are inferior, and the balance is also poor. In addition, in the case of Comparative Example 5 in which the IPN is not implemented in the pressure-sensitive adhesive, it was confirmed that the durability and light transmittance uniformity of the pressure-sensitive adhesive is greatly inferior.

Claims (18)

Crosslinkable acrylic polymer having a weight average molecular weight of more than 500,000 and less than 1 million; A non-crosslinkable acrylic polymer containing more than 0 parts by weight based on 100 parts by weight of the crosslinkable acrylic polymer and 100 parts by weight or less and a multifunctional crosslinking agent contained in an amount of 0.01 parts by weight to 10 parts by weight based on 100 parts by weight of the crosslinkable acrylic polymer. Including, A pressure-sensitive adhesive composition for implementing an interpenetrating polymer network structure in a cured state. The method of claim 1, wherein the crosslinkable acrylic polymer comprises: 80 parts by weight to 99.8 parts by weight of a (meth) acrylic acid ester monomer; And 0.01 to 10 parts by weight of the crosslinkable monomer. The pressure-sensitive adhesive composition of claim 1, 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. delete delete delete The pressure-sensitive adhesive composition of claim 1, further comprising a multifunctional acrylate. 8. The pressure-sensitive adhesive composition of claim 7, wherein the multifunctional acrylate is a bifunctional acrylate, a trifunctional acrylate, a tetrafunctional acrylate, a 5-functional acrylate or a six-functional acrylate. The pressure-sensitive adhesive composition of claim 7, wherein the multifunctional acrylate comprises a ring structure in the molecular structure. The pressure-sensitive adhesive composition according to claim 7, wherein the multifunctional acrylate is contained in an amount of more than 5 parts by weight and less than 15 parts by weight with respect to 100 parts by weight of the crosslinkable acrylic polymer. The pressure-sensitive adhesive composition of claim 1, further comprising a photoinitiator. The photoinitiator is a benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylanino acetophenone , 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1one, 1-hydroxycyclohexyl Phenyl ketone, 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-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p- Dimethylamino Benzoate , Oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone] and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide The adhesive composition which is above. The pressure-sensitive adhesive composition of claim 11, wherein the photoinitiator is included in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the crosslinkable acrylic polymer. The pressure-sensitive adhesive composition of claim 1, further comprising a silane coupling agent. The pressure-sensitive adhesive composition of claim 1, further comprising a tackifying resin. Polarizing film; And a pressure-sensitive adhesive layer formed on one side or both sides of the polarizing film and comprising a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 3 or 7 to 15. The polarizing film of claim 16, further comprising: a polarizer; And a protective film formed on one or both surfaces of the polarizer. The liquid crystal display of claim 16, wherein the polarizing plate of claim 16 comprises a liquid crystal panel attached to one or both surfaces thereof.