KR20080020780A - Pressure sensitive adhesive composition and polarized plate using the same - Google Patents

Abstract

An adhesive composition is provided to significantly reduce the curing time and to improve the productivity by inducing rapid crosslinking, when fabricating a polarizing plate and a liquid crystal display device. An adhesive composition comprises: (a) a polymer having an epoxy pendant group; (b) an amine-based multi-functional crosslinking agent; and (c) a silane coupling agent. The polymer having a pendant epoxy group is an acrylic copolymer obtained by copolymerizing a (meth)acrylate monomer for preparing a homopolymer having a glass transition temperature of -90 to 10 deg.C, an epoxy group-containing acrylic monomer and a monomer having other functional groups.

Description

PRESSURE SENSITIVE ADHESIVE COMPOSITION AND POLARIZED PLATE USING THE SAME}

The present invention relates to an adhesive composition and a polarizing plate using the same. More specifically, the present invention relates to a pressure-sensitive adhesive composition and a polarizing plate using the same, which can greatly improve productivity by shortening the curing period.

The main structure for forming the liquid crystal display device is a multi-layer which is incorporated into an adhesive layer or an adhesive layer based on a liquid crystal cell composed of a liquid crystal layer which is constantly arranged, and a transparent glass plate or plastic plate-like material including a transparent electrode layer. It is common to include polarizing plates, retardation plates, and further functional film layers, etc. of the structure. In order to manufacture such a liquid crystal display device, a liquid crystal cell containing a liquid crystal and a polarizing plate are basically required, and an appropriate adhesive layer or adhesive layer for bonding them should be used. In addition, in order to improve the function of the liquid crystal display, a retardation plate, a wide viewing angle compensation plate, or a brightness enhancement film may be additionally attached to the polarizing plate. Such a lamination process of an adhesive in the manufacturing process of a polarizing plate can be divided roughly into two.

First, after attaching a protective film on one side of the polarizing plate, laminating an adhesive layer on the opposite side, laminating a release film on this adhesive layer, or first laminating an adhesive on the release film, and the adhesive processing surface is the polarizing plate Is a method of manufacturing a polarizing plate laminate by laminating it on the opposite side of the surface on which a protective film is formed, and secondly, a method of transferring a cured pressure-sensitive adhesive transfer tape directly onto a polarizing plate or a retardation plate with an adhesive machine. -177241, JP 2003-147288].

Each laminate of the films has different physical properties because they are made of a material having a different molecular structure and composition. In particular, under thermal or wet heat conditions, dimensional stability due to shrinkage or expansion of materials having a constant directional molecular arrangement is lacking. Accordingly, when the polarizing plate is fixed by the pressure-sensitive adhesive, the strain stress due to the heat or wet heat environment remains, and thus light leakage occurs in the stress concentrated part.

One way to improve the light leakage phenomenon is to allow the pressure-sensitive adhesive to absorb and remove the stress generated in the liquid crystal panel of the polarizing plate in order to reduce the shrinkage of the polarizing plate under heat or wet heat conditions. To this end, US Pat. No. 5,795,650 adds a plasticizer to the pressure-sensitive adhesive layer to impart a function of relieving stress in the pressure-sensitive adhesive. In addition, Japanese Patent Application Laid-open No. Hei 10-279907 proposes a method of improving the light leakage phenomenon by mixing a high molecular weight acrylic polymer and a low molecular weight acrylic polymer having a molecular weight of 30,000 or less to impart relaxation characteristics to stresses generated from a polarizing plate.

In addition, a method of imparting the flow characteristics of the pressure-sensitive adhesive due to the uncrosslinked portion by adding a plasticizer or a low molecular weight material has been reported.

The above-mentioned pressure-sensitive adhesive layer achieves the effect of preventing light leakage due to stress relaxation, but in the case of the pressure-sensitive adhesive to which the flow property is imparted, the cohesive force of the pressure-sensitive adhesive is weak so that it is durable and cutable (cutting the polarizing plate to an appropriate size to cut it cleanly). Properties such as properties) were not satisfactory.

In addition, the pressure-sensitive adhesive is not only to satisfy the above properties, but also considering the industrial applicability, it is also important to improve productivity by shortening the curing period. The curing period means a time when the polymers crosslink each other and become a solid that does not dissolve in a solvent.

The crosslinking agent used to crosslink the polymers can be broadly divided into isocyanate-based, epoxy-based, and aziridine-based. Among the most commonly used crosslinking agents, a substance containing two or more isocyanate functional groups, such as trimethylolpropantolylene isocyanate, and reacted with alcohol functional groups, acid functional groups or amide functional groups of the polymer by a reaction mechanism such as Scheme 1 below. The polymers are connected to each other (Japanese Patent Laid-Open Publication No. 07-155637, Japanese Patent Laid-Open Publication 08-024832, Japanese Patent Laid-Open Publication 08-166628, Japanese Patent Laid-Open Publication 08-220700, Japanese Patent Laid-Open Publication 08-220701). Thus, in order to use isocyanates as crosslinking agents, the polymer must contain functional groups capable of reacting with isocyanates such as hydroxy groups, acid groups or amide groups.

In addition, in the case of the isocyanate crosslinking agent, the excess isocyanate functional group reacts with moisture to generate carbon dioxide, which may cause the lifting phenomenon of the pressure-sensitive adhesive and the adhesive. In addition, in the absence of a catalyst, the rate of crosslinking reaction as in Scheme 1 is very slow, and thus requires a curing period of one week or more.

Scheme 1

The second most commonly used crosslinking agent is a material containing two or more epoxy groups, and the polymers are connected by a reaction mechanism such as the following Scheme 2 (X = O). The expected reactivity of the functional groups reacting with such epoxy crosslinkers is in the order of amine groups, carboxyl groups, hydroxy groups, amide groups, but in the case of the most reactive amine groups, they cannot be introduced into the polymer and thus cannot be applied in practice. Therefore, in the case of using an epoxy crosslinking agent, a polymer containing carboxylic acid is generally used as a functional group [Japanese Laid-Open Patent Publication 07-028823, Japanese Laid-Open Patent Publication 07-028825, Japanese Laid-Open Patent Publication 08-028827, Japanese Laid-Open Patent Publication 08-028831, Japanese Patent Application Laid-Open No. 08-028821]. These epoxy crosslinkers may also be used in admixture with isocyanate crosslinkers.

Scheme 2

Finally, an aziridine crosslinking agent is used as a crosslinking agent of an adhesive composition. Reaction Scheme 2 (X = NH) shows a reaction mechanism between the aziridine crosslinking agent and the polymer, and has a relatively high crosslinking rate compared to epoxy groups or isocyanate groups, but has a problem of poor storage stability and high cost. 125145, JP 2002-148670, JP 2002-148673, JP 2003-098425].

In the case of the isocyanate crosslinking agent which is most used among the three types of crosslinking agents, in order to shorten the curing period, it is necessary to increase the reactivity of the nucleophile (reactive functional group of polymer) and electrophile (reactive functional group of crosslinking agent) participating in the reaction. For this purpose, steric hindrance is using small reactants. Specifically, acrylates containing primary hydroxy groups such as acrylic acid or 2-hydroxyethyl (meth) acrylate, which are highly reactive with isocyanates, are used to increase the reactivity of nucleophiles. Unacrylamide is used as the reactive monomer. In order to increase the reactivity of the electrophiles, isocyanate-based crosslinking agents are used such as hexamethylene diisocyanate or primary isocyanate compounds such as tolylene diisocyanate [Japanese Patent Laid-Open No. 2001-342447, Japanese Patent Laid-Open No. 9-59580]. .

As another method for shortening the curing period of the pressure-sensitive adhesive, a method of adding a crosslinking agent of at least an equivalent of the monomer, that is, a larger number of crosslinking agents than a functional group contained in the polymer, is generally used with respect to the reactive monomer inherent in the polymer. However, the method of shortening the curing period by this method is limited, and the curing period could not be shortened sufficiently.

As a result of repeated studies to solve the above-mentioned problems of the prior art, the present inventors have introduced a epoxy group into the side chain of the polymer, and when the amine-based multifunctional crosslinking agent capable of reacting with an epoxy group is used as a crosslinking agent, It turns out that it can be shortened.

Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive composition that can greatly shorten the curing period. In addition, an object of the present invention is to provide a polarizing plate and a liquid crystal display device using the pressure-sensitive adhesive composition.

In order to achieve the above object, the present invention provides a pressure-sensitive adhesive composition comprising a) a polymer having an epoxy group in the side chain, b) an amine-based multifunctional crosslinking agent, and c) a silane coupling agent.

As long as the a) polymer having an epoxy group in the side chain and b) the amine-based polyfunctional crosslinking agent can have the relationship of Scheme 3 below, any one can be used. This will be described in detail below.

Scheme 3

The a) polymer having an epoxy group in the side chain may be any one as long as it has an epoxy group in the side chain, but a (meth) acrylic acid ester monomer for producing a homopolymer having a glass transition temperature of -90 ° C to 10 ° C, and an acrylic monomer containing an epoxy group. And an acrylic copolymer obtained by copolymerizing a monomer having another functional group if necessary.

The polymer containing the (meth) acrylic acid ester monomer for producing a homopolymer having a glass transition temperature of -90 ° C to 10 ° C reinforces the cohesion by adjusting the weight part (content) of the reactive functional group in the polymer, thereby improving adhesive durability and cutting properties. Can be improved or, conversely, stress relaxation characteristics can be improved. As described above, the homopolymer of the monomer having a low glass transition temperature has a soft property and thus exhibits an initial adhesive force and a stress relaxation phenomenon. The homopolymer of a monomer containing a reactive functional group improves the durability of the adhesive due to the high glass transition temperature. . It is advantageous to use (meth) acrylic acid ester monomers for preparing homopolymers which preferably have a glass transition temperature of -80 ° C to -10 ° C.

Examples of the (meth) acrylic acid ester monomer for preparing a homopolymer having a glass transition temperature of -90 ° C to 10 ° C include n-octyl acrylate, 2-ethylhexyl acrylate, 2-ethylbutyl acrylate, hexyl acrylate and heptyl acryl Laten, nonyl acrylate, pentyl acrylate, isooctyl acrylate, n-decyl methacrylate, n-dodecyl methacrylate n-butyl acrylate, isobutyl acrylate, propyl acrylate, ethyl acrylate, methyl acrylate Elate, 3-methylbutyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-tetradecyl methacrylate, etc. These monomers can be used individually or in mixture of 2 or more types.

Examples of the acrylic monomer including the epoxy group include glycidyl methacrylate, methylglycidyl methacrylate, and cyclic epoxy methacrylates such as Dieser Chemical Co., Ltd .: M100, A400, and the like, or two or more thereof. It can mix and use the above.

In addition, examples of the acrylic monomer having another functional group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, and 2- Although hydroxypropylene glycol (meth) acrylate, acrylamide, etc. are included, it is preferable not to use the acrylic acid monomer which has a functional group containing the carboxylic acid which is relatively reactive with epoxy.

In addition to the present invention, all of the vinyl monomers including a hydroxyl group or an imide group may be used. The aforementioned components can be used alone or in combination if necessary.

The (meth) acrylic acid ester monomer for producing a homopolymer having a glass transition temperature of -90 ° C to 10 ° C is preferably 80 parts by weight to 99 parts by weight in 100 parts by weight of the polymer, and 90 to 95 parts by weight is added for copolymerization. More preferred.

The content of the monomer containing the epoxy group is a) 0.2 parts by weight to 10 parts by weight in 100 parts by weight of the polymer, more preferably 0.5 to 5 parts by weight to copolymerize. At this time, when the content of the monomer containing the epoxy group exceeds 10 parts by weight, there is a problem in reducing the residual stress due to an excessive crosslinking reaction, and when less than 0.2 parts by weight, the cohesive force is reduced due to the insufficient crosslinking degree, resulting in adhesive durability and cutability. It gives the result of harming the property.

In addition, the content of the acrylic monomer having other functional groups is preferably a) 0.1 part by weight to 15 parts by weight, and more preferably 1 to 8 parts by weight to copolymerize in 100 parts by weight of the polymer. At this time, when the content of the monomer containing the other functional groups exceeds 15 parts by weight, the residual stress relaxation effect is relatively low, and when less than 0.1 parts by weight, the cohesive force of the pressure-sensitive adhesive is small, so that the adhesive durability and the cutting properties Hatch gives the result.

The present invention may copolymerize the above-mentioned monomers to produce an acrylic copolymer, the molecular weight of the acrylic copolymer is preferably in the range of 200,000 to 2,500,000 molecular weight in consideration of adhesive properties and coating properties. The method for producing the acrylic copolymer is not particularly limited, and may be prepared by solution polymerization, photopolymerization, bulk polymerization, suspension polymerization or emulsion polymerization. Preferably, the acrylic copolymer is prepared using a solution polymerization method, the polymerization temperature is preferably 50 ~ 110 ℃, it is preferable to add the initiator in a state where the monomers are uniformly mixed. However, it should be noted that since the crosslinking agent used in the present invention is an amine crosslinking agent, an ester solvent such as ethyl acetate which is reacted with the amine cannot be used as a solvent of the solution polymerization method.

In the pressure-sensitive adhesive composition of the present invention, the b) amine-based multifunctional crosslinking agent serves to increase the cohesive force of the pressure-sensitive adhesive by reacting with the epoxy group inherent in the polymer. As the amine-based polyfunctional crosslinking agent, any compound having two or more primary or secondary amine groups capable of reacting with an epoxy group in a molecule may be used.

Specifically, as an amine polyfunctional crosslinking agent, ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, 1,4-diaminobutane, 1,2-diamino-2-methylpropane, 1,5-diaminopentane, 2,2-dimethyl-1,3-propanediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,12-diaminododecane, diethylenetriamine, N- (2-aminoethyl) -1,3-propanediamine, N- (3-aminopropyl) -1,3 Propanediamine, spermidine, bis (hexamethylene) triamine, 4- (aminomethyl) -1,8-octanediamine, triethylenetetramine, N, N-bis (2-aminoethyl) -1,3- Propanediamine, spermine, tris (2-aminoethyl) amine, pentaethylenehexamine, 4,4'-methylenebis (cyclohexylamine), cis 1,2-diaminocyclohexane, trans 1,2-dia Minocyclohexane, cis 1,4-diaminocyclohexane, trans 1,4-diaminocyclohexane, 1,3-cycle Hexanebis (methylamine), 1,8-diamino-paramethane, 5-amino-1,3,3-trimethylcyclohexanemethylamine, 2,2 '-(ethylenedioxy) -bis (ethylamine), 4,7,10-trioxa-1,13-tritecandiamine, 1,3-diamino-2-hydroxypropane and the like.

The amine-based multifunctional crosslinking agent is preferably used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polymer. When the content of the amine-based multifunctional crosslinking agent exceeds 10 parts by weight, there is a problem in relieving residual stress due to excessive crosslinking reaction, and when the content of the amine-based multifunctional crosslinking agent is less than 0.1 part by weight, the cohesive strength is reduced due to the insufficient crosslinking degree. Hatch gives the result.

In the pressure-sensitive adhesive composition of the present invention, the c) silane coupling agent serves to connect the pressure-sensitive adhesive and the substrate, for example, the liquid crystal cell, it is preferable to use a silane coupling agent containing an epoxy group. In this case, the epoxy group in the molecule is bonded to the reactive functional group of the polymer, and the alkoxysilane moiety is strongly bonded to the substrate, for example, the glass substrate of the liquid crystal cell, thereby improving the adhesion stability to further improve the heat and moisture resistance characteristics, and the silane coupling agent Especially when it is left for a long time under high temperature and high humidity, it helps to improve adhesion reliability. As an example thereof, gamma glycidoxy propyl trimethoxysilane can be mentioned. The content of the silane coupling agent is preferably used in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the polymer.

The pressure-sensitive adhesive composition according to the present invention showed storage stability without any particular process problem in the coating process after 48 hours.

The adhesive composition according to the present invention may have a crosslinking density of 5 to 100%, preferably 60 to 95%, in consideration of an optimal physical balance. The above-mentioned crosslinking density can be obtained by weight% of the part which formed the crosslinked structure which is not dissolved in a solvent through the gel content measurement method of the acrylic adhesive generally known.

The pressure-sensitive adhesive composition according to the present invention may further include a tackifying resin to adjust the adhesive performance, the content of which may be used in the range of 1 to 100 parts by weight based on 100 parts by weight of the a) polymer. At this time, when the tackifying resin is used in an excessive amount, the compatibility or cohesion force of the pressure-sensitive adhesive may be reduced, so it should be appropriately added. Examples of the tackifying resins include (hydrogenated) hydrocarbon resins, (hydrogenated) rosin resins, (hydrogenated) rosin ester resins, (hydrogenated) terpene resins, (hydrogenated) terpene phenol resins, polymerized rosin resins, and polymerized rosin Ester resin etc. can be used, These can be used individually or in mixture of 2 or more types.

In addition, in the present invention, a plasticizer, a curing agent, and the like may be further mixed and used for a specific purpose, and an ultraviolet stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, or the like may be appropriately added according to a general purpose.

In addition, the present invention provides a polarizing plate comprising a pressure-sensitive adhesive layer formed using the acrylic pressure-sensitive adhesive composition.

The polarizing plate of this invention contains the adhesive layer formed from the said adhesive composition in the one or both surfaces on the protective film laminated | stacked on the outer surface of the polarizing film, The polarizing film or polarizing element which comprises a polarizing plate is not specifically limited.

Preferably, the polarizing film includes, for example, a film obtained by containing a polarizing component such as iodine or a dichroic dye in a film made of polyvinyl alcohol-based resin and stretching. The thickness of these polarizing films is also not particularly limited, and can be formed to a conventional thickness. In this case, the polyvinyl alcohol-based resin may be polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, and saponified products of ethylene and vinyl acetate copolymer.

The polarizing plate may be formed on both surfaces of the polarizing film such as cellulose-based film such as triacetyl cellulose, polycarbonate film, polyester-based film such as polyethylene terephthalate, polyethersulfone-based film, polyethylene-based film, polypropylene-based film, cyclo- or nord Polyolefin-based having a bornen structure, a protective film such as a polyolefin-based film such as ethylene and propylene copolymer may be formed in a multi-layer structure laminated. At this time, the thickness of these protective films is also not particularly limited, and may be formed to a conventional thickness. The kind of protective film provided on both surfaces of the polarizing film may be the same or different.

In the present invention, the method of forming the pressure-sensitive adhesive layer on the polarizing plate is not particularly limited, and the method of applying and drying the pressure-sensitive adhesive composition using a bar coater or the like directly on the surface of the polarizing plate, or applying the pressure-sensitive adhesive to the surface of the peelable substrate once After drying, the method of transferring the adhesive layer formed on the surface of this peelable base material to the polarizing plate surface, and then aging may be applied.

In addition, the polarizing plate of the present invention may be laminated with one or more layers that provide additional functions such as a protective layer, a reflective layer, an antiglare layer, a retardation plate, a wide viewing angle compensation film and a brightness enhancement film.

The polarizing plate including the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to the present invention can be applied to any conventional liquid crystal display device, and the kind of the liquid crystal panel is not particularly limited. Preferably, the present invention may comprise a liquid crystal display device including a liquid crystal panel in which a polarizing plate including the pressure-sensitive adhesive layer is bonded to one or both surfaces of a liquid crystal cell.

In addition, the pressure-sensitive adhesive composition according to the present invention can also be used for bonding other functional films such as retardation plates used in liquid crystal display elements.

As described above, the pressure-sensitive adhesive composition according to the present invention is excellent in the main physical properties such as adhesion durability, cutting properties, stress relaxation (light leakage phenomenon), and at the same time can significantly shorten the curing period can greatly improve productivity.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the following Examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

<Acryl Copolymer Preparation>

[Production Example 1]

95 parts by weight of n-butyl acrylate (BA), 1.0 part by weight of glycidyl methacrylate (GMA), and 2 parts by weight of methyl methacrylate in a 1 L reactor equipped with a refrigeration system for reflux of nitrogen gas and for easy temperature control. A mixture of monomers consisting of 2 parts by weight of 2-hydroxyethyl acrylate was added. Then, 100 parts by weight of toluene was added as a solvent. After purging with nitrogen gas for 60 minutes to remove oxygen, the temperature was maintained at 60 ° C., and 0.03 parts by weight of azobisisobutyronitrile (AIBN), a reaction initiator, was diluted with toluene at 25% concentration and added for 8 hours. Toluene was added and diluted to a solid content concentration of 15%, and a final acrylic copolymer was prepared to obtain a polymer solution having a weight average molecular weight of 550,000 (polystyrene equivalent).

[Production Example 2]

By using a mixture of monomers consisting of 91 parts by weight of butyl acrylate (BA), 5.0 parts by weight of glycidyl methacrylate (GMA), 2 parts by weight of methyl methacrylate, and 2 parts by weight of 2-hydroxyethyl acrylate. Proceeding as in Production Example 1, a polymer solution of 530,000 in solid content concentration of 15% weight average molecular weight was obtained.

[Production Example 3]

By using a mixture of monomers consisting of 86 parts by weight of butyl acrylate (BA), 10 parts by weight of glycidyl methacrylate (GMA), 2 parts by weight of methyl methacrylate, and 2 parts by weight of 2-hydroxyethyl acrylate. Proceeding as in Production Example 1, a polymer solution having a solid content concentration of 15% weight average molecular weight of 570,000 (polystyrene equivalent) was obtained.

[Production Example 4]

All the reaction was carried out under the same conditions except that methylglycidyl methacrylate was used instead of glycidyl methacrylate in Production Example 2 to obtain a polymer solution having a solid content concentration of 15% weight average molecular weight of 500,000 (polystyrene equivalent).

Production Example 5

In Preparation Example 2, except that glycidyl methacrylate was used instead of cyclic epoxy methacrylate (Dyser Chemical Co., Ltd .: M100), all the reactions were carried out under the same conditions, and the solid content concentration 15% weight average molecular weight 580,000 (polystyrene conversion). ), A polymer solution was obtained.

[Manufacture example 6]

In Preparation Example 2, except that glycidyl methacrylate was used instead of cyclic epoxy methacrylate (Dyser Chemical Co., Ltd .: A400), the reaction was carried out under the same conditions, and the solid content concentration was 15% by weight average molecular weight 620,000 (polystyrene conversion). ), A polymer solution was obtained.

Example 1

To 100 parts by weight of the acrylic copolymer obtained in Preparation Example 1, 0.5 part by weight of tris (2-aminoethyl) amine and 0.2 part by weight of KBM-403 (gamma glycidoxypropyltrimethoxysilane) were added as a crosslinking agent, followed by stirring at room temperature for 30 minutes. . This was dried on two PET films (25cm × 20cm) coated with a release agent using an applicator, and then coated to have a thickness of 25 microns, respectively, and 100 ° C. The oven was dried in a forced hot air dryer for 3 minutes. One sample was laminated by laminating another release film on the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer in the form of NCF (non-carrier film), and stored in a thermo-hygrostat (60%, 25 ° C) for gel fraction analysis. , The other sheet was adhered to the polarizing plate as in the following <plywood process> to evaluate the durability.

Example 2

It proceeded in the same manner as in Example 1, using 2 parts by weight of tris (2-aminoethyl) amine as the crosslinking agent to 100 parts by weight of the acrylic copolymer obtained in Production Example 2.

Example 3

It proceeded in the same manner as in Example 1 using 4 parts by weight of tris (2-aminoethyl) amine as the crosslinking agent to 100 parts by weight of the acrylic copolymer obtained in Production Example 3.

Example 4

100 parts by weight of the acrylic copolymer obtained in Production Example 2 was used in the same manner as in Example 1, using 2 parts by weight of pentaethylenehexamine as a crosslinking agent.

Example 5

It proceeded in the same manner as in Example 1 using 2 parts by weight of hexaethylenediamine as a crosslinking agent to 100 parts by weight of the acrylic copolymer obtained in Production Example 2.

Example 6

It proceeded in the same manner as in Example 1 using 2 parts by weight of tris (2-aminoethyl) amine as a crosslinking agent to 100 parts by weight of the acrylic copolymer obtained in Production Example 4.

Example 7

It proceeded in the same manner as in Example 1 using 2 parts by weight of tris (2-aminoethyl) amine as the crosslinking agent to 100 parts by weight of the acrylic copolymer obtained in Production Example 5.

Example 8

It proceeded in the same manner as in Example 1 using 2 parts by weight of tris (2-aminoethyl) amine as the crosslinking agent to 100 parts by weight of the acrylic copolymer obtained in Production Example 6.

Comparative Example 1

95 parts by weight of n-butyl acrylate (BA), 1.0 parts by weight of acrylic acid, 2 parts by weight of methyl methacrylate, 2-hydroxyethyl acrylate in a 1L reactor equipped with a refrigeration system for easy reflux of nitrogen gas A mixture of monomers consisting of 2 parts by weight was added. Then, 100 parts by weight of toluene was added as a solvent. After purging with nitrogen gas for 60 minutes to remove oxygen, the temperature was maintained at 60 ° C., 0.03 parts by weight of azobisisobutyronitrile (AIBN), a reaction initiator, was diluted in toluene at 25% concentration, and added for 8 hours. Reacted. Subsequently, toluene was added and diluted so as to have a solid content concentration of 15%, and a final acrylic copolymer was prepared to obtain a polymer solution having a weight average molecular weight of 530,000.

2 parts by weight of tolylene diisocyanate adduct (coronate-L) of isocyanate-based trimethylolpropane and 0.2 parts by weight of KBM-403 (gamma epoxypropyl trimethoxysilane) were added to 100 parts by weight of the acrylic copolymer thus obtained. And mixed. This was coated on two PET films (25 cm × 20 cm) coated with a release agent, and dried in a forced circulation hot air dryer of 100 ° C. oven to obtain a 25 micron uniform adhesive layer. One sample was laminated by laminating another layer of release film on the pressure-sensitive adhesive layer to obtain an NCF-type pressure-sensitive adhesive layer and stored in a thermo-hygrostat (60%, 25 ° C.). Evaluated.

<Evaluation test>

NCF Of type adhesive Gel %analysis ( Curing time  Measure)

The NCF prepared in the above was cut to an appropriate size and weighed, and immersed in ethyl acetate solvent, stored at room temperature for 48 hours, dried for 2 hours in a vacuum oven at 60 ° C., and then the difference in weight was measured. The fraction was measured.

<Plywood process>

The pressure-sensitive adhesive layer prepared above was adhered to an iodine-based polarizing plate having a thickness of 185 microns, and stored in a thermo-hygrostat (60%, 25 ° C). The obtained polarizing plate was cut | disconnected to the appropriate magnitude | size, and was used for evaluation.

Durability Reliability  evaluation

The pressure-sensitive adhesive coated polarizing plate (250mm × 200mm) prepared above was cut into a size of a glass substrate (200mm × 200mm × 0.7mm) and attached to both surfaces of the glass substrate in a state where the optical absorption axis of the polarizing plate was crossed. At this time, the pressure applied was about 5kg / cm ² and the clean room operation was performed so that no bubbles or foreign substances were generated. The specimens were left for 500 hours at 60 ° C and 90% relative humidity to observe the heat and moisture resistance. The heat resistance was observed at 80 ℃, 500 hours after the bubble or peeling. Immediately after evaluating the state of the specimen was performed at room temperature for 24 hours. The evaluation criteria for reliability are as follows.

○: no bubbles or peeling

△: bubble or peeling phenomenon

×: bubble or peeling phenomenon

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Comparative Example 1 Curing Period ^* (> 90%) 5 days 3 days 2 days 2 days 2 days 2 days 1 day 1 day 15th durability Ο Ο Ο Ο Ο Ο Ο Ο Ο *: The curing period represents the number of days it took for the gel fraction to be 90% or more.

The pressure-sensitive adhesive composition according to the present invention is a curing period in which a gel fraction reaches 90% or more by causing a rapid crosslinking reaction using a polymer having an epoxy group introduced as a reactive functional group and an amine-based multifunctional crosslinking agent capable of reacting with an epoxy group. By shortening to within 5 days, productivity can be improved.

Claims (10)

a) a polymer having an epoxy group in the side chain, b) amine-based multifunctional crosslinking agents, and c) silane coupling agent Pressure-sensitive adhesive composition comprising a. The polymer having an epoxy group in the a) side chain is a (meth) acrylic acid ester monomer for producing a homopolymer having a glass transition temperature of -90 ° C to 10 ° C, an acrylic monomer containing an epoxy group, and a monomer having other functional groups. Pressure-sensitive adhesive composition which is an acrylic copolymer obtained by copolymerizing. The (meth) acrylic acid ester monomer for producing a homopolymer having a glass transition temperature of -90 ° C to 10 ° C is n-octyl acrylate, 2-ethylhexyl acrylate, 2-ethylbutyl acrylate, hexyl acryl. Latex, heptyl acrylate, nonyl acrylate, pentyl acrylate, isooctyl acrylate, n-decyl methacrylate, n-dodecyl methacrylate n-butyl acrylate, isobutyl acrylate, propyl acrylate, ethyl acrylate Pressure-sensitive adhesive composition comprising one or two or more selected from the group consisting of acrylate, methyl acrylate, 3-methylbutyl acrylate, n-hexyl methacrylate, n-octyl methacrylate and n-tetradecyl methacrylate . The pressure-sensitive adhesive composition of claim 2, wherein the acrylic monomer including the epoxy group comprises one or two or more selected from glycidyl methacrylate, methylglycidyl methacrylate, and cyclic epoxy methacrylate. . The monomer according to claim 2, wherein the monomer having other functional groups is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxy Pressure-sensitive adhesive composition containing one or two or more selected from oxypropylene glycol (meth) acrylate and acrylamide The pressure-sensitive adhesive composition of claim 2, wherein the acrylic monomer including the epoxy group is contained in an amount of 0.2 parts by weight to 10 parts by weight in 100 parts by weight of the acrylic copolymer. The pressure-sensitive adhesive composition of claim 1, wherein the b) amine-based multifunctional crosslinking agent is a compound having two or more primary or secondary amine groups in a molecule. The pressure-sensitive adhesive composition of claim 1, wherein b) the amine-based multifunctional crosslinking agent is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the polymer. The polarizing plate containing the adhesive layer formed using the adhesive composition of any one of Claims 1-8. Liquid crystal display comprising the polarizing plate of claim 9.