KR19980079266A - Adhesive composition for polarizing plates and polarizing plate - Google Patents

Abstract

The present invention, 100 parts by weight of a high molecular weight (meth) acrylic copolymer having a copolymer of 0.5 to 20% by weight of a polymerizable monomer having a functionality for an alkyl (meth) acrylate and a crosslinking agent and having a weight average molecular weight of 1 million or more; 20 to 200 parts by weight of a low molecular weight (meth) acrylic (co) polymer having a weight average molecular weight of 30,000 or less, and 0.005 to 5 parts by weight of a polyfunctional compound having at least two functional groups in a molecule, capable of forming a crosslinked structure, Adhesive composition for polarizing plates and adhesive layer formed from this adhesive composition whose functional group distribution ratio represented by the functional group of the molecular weight (meth) acrylic-type (co) polymer / the functional group of a high molecular weight (meth) acrylic-type copolymer exists in the range of 0 to 15 weight%. It relates to a polarizing plate having a.

According to this invention, the adhesive bond layer accompanying a dimensional change of a polarizing plate can be formed, and a color stain does not generate | occur | produce in a liquid crystal element.

Description

Adhesive composition for polarizing plates and polarizing plate

This invention relates to the polarizing plate which has an adhesive for bonding a polarizing plate used for a liquid crystal element etc. to a retardation plate or a board | substrate, and the layer which becomes this adhesive.

The liquid crystal element has a structure in which a liquid crystal component oriented in a predetermined direction is sandwiched between two substrates, and a laminate of a polarizing plate or a polarizing plate and a retardation plate is adhered to the surface of the substrate. Such liquid crystal elements have been used in a wide range of fields as display devices.

Since liquid crystal elements are suitable for weight reduction and thinning of devices, these liquid crystal elements have recently been used as display devices for vehicles, outdoor instruments, displays of personal computers, wall-mounted televisions, and the like. It is coming to be done. Under such severe conditions, a dimensional change of the polarizing plate occurs, and foaming and peeling easily occur due to the dimensional change. The pressure sensitive adhesive for adhering a polarizing plate to a phase plate or a substrate has been improved to increase the molecular weight or increase the degree of crosslinking so that the pressure sensitive adhesive layer can withstand use under severe conditions.

However, increasing the molecular weight of the pressure-sensitive adhesive or increasing the degree of crosslinking so that the pressure-sensitive adhesive layer can withstand the use in harsh conditions is to suppress the dimensional change of the polarizing plate with the pressure-sensitive adhesive. Although possible, internal stress generated by the change of the size of the polarizing plate with long-term use is concentrated on the periphery of the polarizing plate, resulting in color staining on the surface of the liquid crystal element, such that the periphery of the liquid crystal element becomes brighter or darker than the central portion.

Accordingly, Japanese Patent Application Laid-Open No. 60-207101 generally describes (A) an alkyl (meth) acrylate copolymer having a reactive functional group, an (B) alkyl (meth) acrylate (co) polymer having no functional group, and ( C) A pressure-sensitive adhesive layer comprising a polyfunctional compound having at least two functional groups obtained by reacting with the reactive functional group and containing (A) and (B) in a weight ratio of 1: 4 to 4: 1 is polarized. The invention of the polarizing plate laminated | stacked on at least 1 surface of a film is disclosed.

By adopting the above structure, the cohesive force, adhesive force and viscoelasticity of the pressure-sensitive adhesive are excellent and balanced, and the functional groups liberated by crosslinking do not remain, so that the quality is stable and polarized even under conditions of high temperature and high humidity. It is described that no bubbles or interfacial peeling occur in the film and the substrate.

However, in the invention described in this publication, the (A) alkyl (meth) acrylate copolymer having a reactive functional group and the (B) alkyl (meth) acrylate (co) polymer having no functional group are produced under the same reaction conditions. Since it is manufactured, it is thought that the alkyl (meth) acrylate copolymer which has this (A) reactive functional group, and the alkyl (meth) acrylate (co) polymer which does not have (B) functional group have a substantially equivalent molecular weight. That is, this publication does not show the technical idea of using an alkyl (meth) acrylate copolymer having a (A) reactive functional group having a different molecular weight and an alkyl (meth) acrylate (co) polymer having no (B) functional group. not. For this reason, even if the adhesive agent described in this publication is used, the followability of the adhesive bond layer corresponding to the dimensional stability of a polarizing plate will not be expressed.

In addition, Patent Publication No. 2549388 discloses, on the surface of a polarizing plate, a pressure-sensitive adhesive layer composed of an acrylic polymer mainly containing alkyl esters of acrylic acid to methacrylic acid having 1 to 12 carbon atoms of an alkyl group. In the polarizing plate provided, the pressure-sensitive adhesive layer is composed of an acrylic polymer containing 15% by weight or less of a polymer component having a weight average molecular weight of 100,000 or less and 10% by weight or more of a polymer component having a weight average molecular weight of 1 million or more. The invention of the pressure-sensitive adhesive polarizing plate] is disclosed. That is, it is disclosed that this pressure-sensitive adhesive layer is crosslinked, and 15 wt% or less of the uncrosslinked polymer component having a weight average molecular weight of 100,000 or less is contained with respect to the total polymer weight in the crosslinked pressure-sensitive adhesive layer.

In the invention described in this publication, the content of the high molecular weight polymer having a weight average molecular weight of 1 million or more in the pressure-sensitive adhesive layer is contained at a high concentration of 10% by weight or more, but on the contrary, the content of the low molecular weight polymer having a weight average molecular weight of 100,000 or less Silver is 15% by weight or less, and the content of the low molecular weight polymer is reduced in this invention. According to the investigation by the present inventors, if the content rate of the low molecular weight polymer is low, the followability of the pressure-sensitive adhesive layer with respect to the dimensional change of the polarizing plate is low, and it can resist internal stress occurring within a certain range, but repeatedly over a long period of time. The generated internal stress is concentrated on the periphery of the polarizing plate, and color stains are generated on the surface of the liquid crystal element such as the periphery of the liquid crystal element becomes brighter or darker than the center portion. That is, the invention described in this publication is intended to resist internal stress caused by long-term use of the pressure-sensitive adhesive by using a large amount of high molecular weight polymer. Therefore, in the invention disclosed in this publication, the internal stress generated between the bonded polarizing plate and the liquid crystal cell substrate is absorbed by the adhesive layer, and the internal stress generated by long-term use is absorbed, thereby preventing the internal stress between the polarizing plate and the liquid crystal cell substrate. There is no technical idea to correct deformation. Therefore, even using the adhesive agent described in this publication, it is difficult to form the adhesive bond layer which has traceability to the dimensional change of a polarizing plate.

The present invention has a characteristic that follows the dimensional change occurring in the polarizing plate, does not foam even after repeated use for a long period of time under high temperature and high humidity conditions, and does not cause interfacial peeling, thus causing color stains in the peripheral and center portions. It is an object of the present invention to provide a polarizing plate pressure sensitive adhesive capable of forming a liquid crystal element that is not present, and a polarizing plate formed of at least one surface of a layer made of the pressure sensitive adhesive.

The adhesive for polarizing plates of this invention,

(A) A repeating unit derived from the (meth) acrylic acid ester is a main repeating unit, and a repeating unit derived from a functional group-containing monomer having reactivity with the multifunctional compound (C) is copolymerized in an amount of 0.5 to 20% by weight A high molecular weight (meth) acrylic copolymer having a weight average molecular weight of 1 million or more,

To 100 parts by weight of the high molecular weight (meth) acrylic copolymer,

(B) A low molecular weight (meth) acrylic (co) polymer having a weight average molecular weight of 30,000 or less, wherein the repeating unit derived from the functional group-containing monomer reactive with the multifunctional compound (C) is polymerized in an amount of 0 to 10% by weight. 20 to 200 parts by weight,

(C) A multi-tube having at least two functional groups in the molecule which can be combined with the high molecular weight (meth) acrylic copolymer (A) and / or the low molecular weight (meth) acrylic (co) polymer (B) to form a crosslinked structure. Consisting of 0.005 to 5 parts by weight of the functional compound,

The repeating unit derived from the functional group containing monomer which is reactive with respect to the polyfunctional compound (C) copolymerized with the said high molecular weight (meth) acrylic-type copolymer (A) and the low molecular weight (meth) acrylic-type (co) polymer (B) And a high molecular weight (meth) acrylic copolymer (A) and a low molecular weight (meth) acrylic (co) polymer (B) at a functional group distribution ratio represented by the following formula.

Functional group partition ratio = [Multifunctional compound in the monomer equivalent weight / high molecular weight (meth) acrylic copolymer of a repeating unit derived from a functional group-containing monomer having reactivity with the multifunctional compound (C) in a low molecular weight (meth) acrylic copolymer ( Monomer equivalent weight of repeating unit derived from a functional group-containing monomer having reactivity with respect to C)] X 100 = 0 to 15% by weight.

In addition, the polarizing plate of the present invention,

(A) A repeating unit derived from the (meth) acrylic acid ester is a main repeating unit, and a repeating unit derived from a functional group-containing monomer having reactivity with the multifunctional compound (C) is copolymerized in an amount of 0.5 to 20% by weight A high molecular weight (meth) acrylic copolymer having a weight average molecular weight of 1 million or more,

To 100 parts by weight of the high molecular weight (meth) acrylic copolymer,

(B) A low molecular weight (meth) acrylic (co) polymer having a weight average molecular weight of 30,000 or less, wherein the repeating unit derived from the functional group-containing monomer reactive with the multifunctional compound (C) is polymerized in an amount of 0 to 10% by weight. 20 to 200 parts by weight,

(C) A multi-tube having at least two functional groups in the molecule which can be combined with the high molecular weight (meth) acrylic copolymer (A) and / or the low molecular weight (meth) acrylic (co) polymer (B) to form a crosslinked structure. Comprised of 0.005 to 5 parts by weight of the functional compound,

The repeating unit derived from the functional group containing monomer which is reactive with respect to the polyfunctional compound (C) copolymerized with the said high molecular weight (meth) acrylic-type copolymer (A) and the low molecular weight (meth) acrylic-type (co) polymer (B) , The pressure-sensitive adhesive layer made of a pressure-sensitive adhesive, characterized in that contained in a high molecular weight (meth) acrylic copolymer (A) and a low molecular weight (meth) acrylic (co) polymer (B) at a functional group distribution ratio represented by the above formula. It is formed in at least one surface, It is characterized by the above-mentioned.

In the pressure-sensitive adhesive for polarizing plate of the present invention, a high molecular weight (meth) acrylic copolymer having a weight average molecular weight of 1 million or more as a (meth) acrylic copolymer that reacts with a polyfunctional compound, and at the same time, has little or no reactivity with the polyfunctional compound. A functional group having two kinds of different (meth) acrylic polymers of a low molecular weight (meth) acrylic (co) polymer having a weight average molecular weight of 30,000 or less as the (meth) acrylic (co) polymer, and having reactivity with a polyfunctional compound. Since the amount of is less in the lower molecular weight (meth) acrylic (co) polymer than in the high molecular weight (meth) acrylic copolymer, even if the low molecular weight (meth) acrylic copolymer is not combined with the multifunctional compound or It is difficult to form a three-dimensional crosslinked structure. Therefore, according to the use of the pressure-sensitive adhesive of the present invention, a three-dimensional crosslinked structure is formed of a high molecular weight (meth) acrylic copolymer and a polyfunctional compound, and a low molecular weight (meth) acrylic (co) Polymer is present.

In the pressure-sensitive adhesive for polarizing plate of the present invention having such a configuration, the formed three-dimensional structure prevents foaming or peeling occurring under high temperature and high humidity conditions, and the internal stress accompanying the numerical change of the polarizing plate is present in the three-dimensional crosslinked structure. It absorbs by a low molecular weight (meth) acrylic-type (co) polymer, and gives a pressure-sensitive adhesive layer a property to change in accordance with the change in shape of the polarizing plate according to the change in temperature or humidity.

Therefore, in the polarizing film adhered to the substrate or the retardation plate with the pressure-sensitive adhesive, the internal stress generated by the temperature change, the humidity change, etc. is absorbed by the pressure-sensitive adhesive layer, so that the periphery of the liquid crystal element is lighter or darker than the central part. Color stains do not occur, and foaming and peeling do not occur.

Next, the polarizing plate which has the adhesive for polarizing plates of this invention and the adhesive layer which consists of this adhesive is demonstrated concretely.

The adhesive for polarizing plates of this invention contains a high molecular weight (meth) acrylic-type copolymer, a low molecular weight (meth) acrylic-type (co) polymer, and a polyfunctional sulfide compound.

The high molecular weight (meth) acrylic copolymer is a copolymer of a functional group-containing monomer having (meth) acrylic acid ester as a main component and having reactivity with the (meth) acrylic acid ester and the polyfunctional compound (C). As (meth) acrylic acid ester which forms this high molecular weight (meth) acrylic-type copolymer, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, iso -Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acryl Elate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, etc. are mentioned. These can be used individually or in combination.

Moreover, as an example of the functional group containing monomer which is reactive with a polyfunctional compound, the monomer containing carboxyl groups, such as (meth) acrylic acid, beta-carboxyethyl acrylate, itaconic acid, a crodonic acid, maleic acid, maleic anhydride, and butyl maleic acid, 2 -Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol mono ( Monomers containing hydroxy groups such as meth) acrylate and aryl alcohol, aminomethyl (meth) acrylate, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, and Monomers containing amino groups such as vinylpyridine, monomers containing epoxy groups such as glycidyl (meth) acrylate and It sat acetoxy, and the like ethoxyethyl (meth) monomer containing an acetoacetyl group, such as acrylate. These can be used individually or in combination.

Among these, the monomer containing a carboxyl group and the monomer containing a hydroxy group are preferable.

The high molecular weight (meth) acrylic copolymer is 80 to 99.5% by weight, preferably 90 to 99.5% by weight of alkyl (meth) acrylic acid ester, and 0.5 to 20% by weight, preferably 0.5 to 15% by weight of polyfunctional It is a copolymer of the monomer containing the functional group which has reactivity with a compound.

By copolymerizing the alkyl (meth) acrylic acid ester and the polymerizable monomer which has reactivity with a polyfunctional compound in the above amount, it is possible to combine with a polyfunctional compound and form the copolymer which has favorable adhesiveness.

The weight average molecular weight of the said high molecular weight (meth) acrylic-type copolymer which comprises the adhesive composition of this invention needs to be 1 million or more, and it is preferable to exist in the range of 1 to 2 million. By using a high molecular weight (meth) acrylic copolymer in this manner, good adhesion between the substrate and the polarizing plate or the retardation plate and the polarizing plate can be ensured, and foaming or peeling can be prevented.

In the present invention, the high molecular weight (meth) acrylic copolymer is a copolymer of a (meth) acrylic acid ester and a polymerizable monomer having reactivity to a polyfunctional compound. Another monomer may be copolymerized within the range which does not impair the characteristic of a (meth) acrylic-type copolymer.

As an example of another monomer which can be copolymerized here, a vinyl acetate, styrene, methyl styrene, vinyltoluene, acrylonitrile, (meth) acrylamide, N-methyl acrylamide, etc. are mentioned. The amount of polymerization of this monomer is usually 0 to 30% by weight, preferably 0 to 15% by weight relative to 100% by weight of the total amount of the polymerizable monomer having reactivity to the (meth) acrylic acid ester and the polyfunctional compound.

The adhesive for polarizing plates of this invention contains the low molecular weight (meth) acrylic-type (co) polymer. This low molecular weight (meth) acrylic (co) polymer is a non-reactive or low (co) polymer with respect to a polyfunctional compound, and the amount of repeating units derived from a monomer having a functional group reactive with the polyfunctional compound is high in molecular weight ( It is lower than the amount of repeating units derived from the monomer having a functional group present in the meta) acrylic copolymer. That is, this low molecular weight (meth) acrylic-type (co) polymer contains a repeating unit comprising a monomer containing a functional group reactive with a polyfunctional compound, with the repeating unit derived from the (meth) acrylic acid ester as the main repeating unit. Or (co) polymers with very low content. Moreover, this monomer may copolymerize another monomer.

(Meth) acrylic acid esters used in the preparation of low molecular weight (meth) acrylic (co) polymers, monomers containing functional groups reactive to polyfunctional compounds, and other monomers are those described in the high molecular weight (meth) acrylic copolymers. Usually used. Therefore, the weight average molecular weight of this low molecular weight (meth) acrylic-type (co) polymer needs to be 30,000 or less, and it is preferable to exist in the range of 1000-20000. By using the (meth) acrylic-based (co) polymer having such a molecular weight, the pressure-sensitive adhesive layer has good trackability of the pressure-sensitive adhesive layer against dimensional changes due to temperature and humidity of the polarizing plate, and the liquid crystal device has high temperature and high humidity conditions. Since the pressure-sensitive adhesive layer follows the dimensional change even when the polarizing plate is used to change in size, there is no difference between the brightness of the periphery of the liquid crystal element and the brightness of the central part, and color spots and the like do not occur.

The low molecular weight (meth) acrylic (co) polymer is used in an amount of 20 to 200 parts by weight, preferably 30 to 100 parts by weight, based on the high molecular weight (meth) acrylic copolymer. If it is less than 20 weight part, the followability of the adhesive layer with respect to the dimensional change of a polarizing plate will become inadequate, and a color unevenness will not be suppressed. On the other hand, when it uses more than 200 weight part, adhesiveness under high temperature, high humidity will fall, and peeling will generate | occur | produce.

In addition, in this invention, when mixing a high molecular weight (meth) acrylic-type copolymer and a low molecular weight (meth) acrylic-type (co) polymer in the said ratio, in the mixture of both, in the case of each polymer, in the polyfunctional compound (C) It is necessary that the functional group distribution ratio which is the ratio of the monomer conversion weight of the repeating unit derived from the monomer containing the functional group which has a reactivity with respect to it exists in a specific range.

This functional group distribution ratio is represented by the following formula.

Functional group partition ratio = [Multi-functional in monomer-weight-weight / high molecular weight (meth) acrylic copolymer of repeating units derived from monomers containing functional groups reactive with multifunctional compounds (C) in low molecular weight (meth) acrylic copolymers Monomer equivalent weight of repeating unit derived from the monomer containing the functional group which is reactive with respect to compound (C)] X 100.

Thus, in the present invention, the functional group distribution ratio needs to be in the range of 0 to 15% by weight, and preferably in the range of 0 to 10% by weight. This functional group distribution ratio shows the formation method of the crosslinked structure formed by the crosslinking agent (C) (polyfunctional compound) mentioned later, A low molecular weight (meth) acrylic-type (co) polymer is a high molecular weight (meth) acrylic-type copolymer ( A repeating unit derived from a monomer having a functional group in an amount of 15 wt% or less, preferably 10 wt% or less of a repeating unit derived from a functional group-containing monomer having reactivity with respect to the multifunctional compound (C) forming A) With or without this repeating unit. As such, even if the low molecular weight (meth) acrylic (co) polymer does not have or has repeating units derived from monomers containing functional groups reactive to the polyfunctional compound (C), the low molecular weight (meth) The crosslinked structure is not formed or difficult to form in the acrylic (co) polymer, and thus the low molecular weight (meth) acrylic (co) polymer (B) is a high molecular weight (meth) acrylic copolymer (A) and a polyfunctional compound (C). It is possible to move to some extent freely in the three-dimensional crosslinked structure formed by the). The basic adhesive strength of the polarizing plate and the liquid crystal cell substrate is mainly expressed by the three-dimensional crosslinked structure, and the internal stress generated between the polarizing plate and the liquid crystal cell substrate due to long term adhesion is absorbed by the three-dimensional crosslinked structure. Instead, internal torsion occurs due to this internal stress. The adhesive of the present invention can absorb this internal stress by the low molecular weight (meth) acrylic (co) polymer (B). That is, it contains the low molecular weight (meth) acrylic-type (co) polymer (B) of a specific weight average molecular weight in the said quantity, and contains the low molecular weight (meth) acrylic-type (co) polymer (B) whose distribution ratio of a functional group exists in the said range. By doing so, the adhesive layer formed by the adhesive composition of the present invention has form followability in response to the time course change of the polarizing plate. It is possible to suppress color unevenness by improving the form followability.

Therefore, when this functional group distribution ratio exceeds 15 weight%, the reaction rate of a low molecular weight (meth) acrylic-type (co) polymer and a polyfunctional compound increases, and the three-dimensional crosslinking formed from the high molecular weight (meth) acrylic copolymer and a polyfunctional compound Since the fall of the structural quantity occurs, foaming will generate | occur | produce under high temperature, high humidity.

The adhesive for polarizing plates of this invention contains a polyfunctional compound as a polyfunctional compound. The functional group of this compound reacts with the functional group which has the reactivity of the said (meth) acrylic-type polymer, and has at least 2 functional group in 1 molecule, Preferably it has 2-4.

As an example of such a polyfunctional compound, an isocyanate type compound, an epoxy type compound, an amine type compound, a metal chelate type compound, an aziridine type compound, etc. are mentioned.

As an example of an isocyanate type compound, triene diisocyanate, hexamethylene diisocyanate, isoform diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylene diisocyanate And receptors with polyols such as naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, and trimethylolpropane, and the like.

Moreover, as an example of an epoxy type compound, bisphenol A and epichlorhydrin type epoxy resin. Ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycol Cydylaniline, diglycidylamine, N, N, N ', N'-tetraglycidyl-m-xylenediamine and 1,3-bis (N, N'-diglycidylaminemethyl) cyclohexane Etc. can be mentioned.

Examples of the amine compound include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isoformdiamine, amino resins and methylene resins.

Examples of the metal chelate compound include compounds in which polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium are assigned to acetylacetone or ethyl acetoacetate. have.

In addition, examples of the aziridine-based compound include N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxide) and N, N'-toluene-2,4-bis (1-aziridine Carboxyside), triethylenemelamine, bisisophthaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N'-hexamethylene-1,6-bis (1 -Aziridinecarboxyl), trimethylolpropane-tri-beta-aziridinylpropionate, tetramethylolmethane-tri-beta-aziridinylpropionate, and the like.

Such a polyfunctional compound is normally used in the quantity of 0.005-5 weight part, Preferably it is 0.01-3 weight part with respect to 100 weight part of said high molecular weight (meth) acrylic-type copolymers. By using a polyfunctional compound in such quantity, a preferable three-dimensional crosslinked structure is formed between the said high molecular weight (meth) acrylic-type copolymer. In addition, these polyfunctional compounds can be used individually or in combination.

Any known method may be employed for producing the high molecular weight (meth) acrylic copolymer and the low molecular weight (meth) acrylic (co) polymer constituting the pressure-sensitive adhesive for polarizing plates of the present invention.

For example, the high molecular weight (meth) acrylic copolymer. 0.01 to 1 part by weight of polymerization initiator (azo-based polymerization initiators such as azobisisobutyronitrile, azobiscyclohexanecarbonitrile, peroxides such as benzoyl peroxide and acetyl peroxide, diphenyl ketone, 2- Photopolymerization initiators such as hydroxy-2-methyl-1-phenyl-propan-1-one and the like), and are synthesized by a method such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and preferably solution polymerization. Are synthesized.

In the case of the solution polymerization method, ethyl acetate, toluene, hexane, acetone and the like are used as the polymerization solution, and the reaction temperature is 50 to 150 ° C, preferably 50 to 110 ° C, and the reaction time is 3 to 15 hours, preferably 5 To 10 hours.

The low molecular weight (meth) acrylic (co) polymer is synthesized by a method such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and the like, preferably by solution polymerization, like the high molecular weight acrylic copolymer. However, since the weight average molecular weight is 30,000 or less, the amount of the polymerization initiator is about 10 to 100 times higher than in the case of the high molecular weight acrylic copolymer, and preferably lauryl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan Chain transfer agents such as mercaptan, alpha-methyl styrene dimer and limonene, and the like are used.

The adhesive for polarizing plates of this invention can be manufactured by mixing the high molecular weight (meth) acrylic-type copolymer, the low molecular weight (meth) acrylic-type (co) polymer, and the polyfunctional compound which were produced as mentioned above.

At this time, the low molecular weight (meth) acrylic (co) polymer is 20 to 200 parts by weight, preferably 30 to 150 parts by weight, and the polyfunctional compound is 100 parts by weight based on 100 parts by weight of the high molecular weight (meth) acrylic copolymer. It is contained in the quantity of 0.005-5 weight part, Preferably it is 0.01-3 weight part with respect to 100 weight part of molecular weight (meth) acrylic-type copolymers.

The pressure sensitive adhesive for polarizing plates of the present invention is made of a high molecular weight (meth) acrylic copolymer, a low molecular weight (meth) acrylic (co) polymer, and a polyfunctional compound as described above, and the weathering stabilizer usually blended in the pressure sensitive adhesive for the polarizing plate , Tachyfires, plasticizers, softeners, dyes, pigments, silane coupling agents, inorganic fillers, and the like.

The polarizing plate of this invention laminates the adhesive layer formed from the said adhesive on one surface of a polarizing film.

As a polarizing film used by this invention, a conventionally well-known polarizing film can be used.

For example, a film made of polyvinyl alcohol-based resin such as polyvinyl alcohol, polyvinyl formal, polyvinyl acetal and saponified ethylene-vinyl acetate copolymer is contained in a polarizing component such as iodine or dichroic dye and stretched. The multilayer film etc. which laminated | stacked protective films, such as cellulose-type films, such as cellulose acetate, a polycarbonate film, and a polyether sulfone type film, can be used for the film obtained by making it the above.

There is no restriction | limiting in particular in the method of forming an adhesive layer in such a polarizing film, Although the method of apply | coating and drying the said adhesive using a bar coater etc. directly on this polarizing film surface can be employ | adopted, The said adhesive is once peelable base material After apply | coating to a surface and drying, it is preferable to employ | adopt the method of transferring the adhesive layer formed in the surface of this peelable base material to the polarizing film surface, and then aging.

The thickness of the pressure-sensitive adhesive layer thus formed is usually in the range of 10 to 100 um, preferably 20 to 50 um in dry thickness.

In addition, this adhesive layer should just be formed in at least one surface of a polarizing film, and can also form this adhesive layer in both surfaces of a polarizing film in this invention.

Moreover, the layer which has another function, such as a protective layer, a reflection layer, an glare-proof layer, may be laminated | stacked on the polarizing plate of this invention, for example.

Example

Next, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.

(Polymer solution 1)

95 parts by weight of n-butyl acrylate, 5 parts by weight of acrylic acid, 100 parts by weight of ethyl acetate and 0.2 parts by weight of benzoyl peroxide are placed in a reaction vessel, the air in the reaction vessel is replaced with nitrogen gas, and the reaction is carried out in a nitrogen atmosphere under stirring. The solution was heated to 66 ° C. and reacted for 10 hours. After the reaction, the mixture was diluted with ethyl acetate to obtain a (meth) acrylic polymer solution having a solid content of 20% by weight.

(Polymer solution 2)

89 parts by weight of n-butyl acrylate, 10 parts by weight of benzyl acrylate, 1 part by weight of 2-hydroxyethyl acrylate, 100 parts by weight of ethyl acetate and 0.2 parts by weight of azobisisobutyronitrile were placed in a reaction vessel, and this reaction vessel After replacing the air inside with nitrogen gas, this reaction solution was heated up at 66 degreeC in nitrogen atmosphere under stirring, and it was made to react for 10 hours. After the reaction, the mixture was diluted with ethyl acetate to obtain a (meth) acrylic polymer solution having a solid content of 22% by weight.

(Polymer solution 3)

90 parts by weight of n-butyl acrylate, 10 parts by weight of benzyl acrylate, 100 parts by weight of ethyl acetate and 0.2 parts by weight of azobisisobutyronitrile were placed in a reaction vessel, and the air in the reaction vessel was replaced with nitrogen gas, followed by stirring. The reaction solution was heated up at 66 ° C. in a nitrogen atmosphere, and reacted for 15 hours. After the reaction, the mixture was diluted with ethyl acetate to obtain a (meth) acrylic polymer solution having a solid content of 22% by weight.

(Polymer solution 4)

95 parts by weight of n-butyl acrylate, 5 parts by weight of acrylic acid, 120 parts by weight of ethyl acetate, 30 parts by weight of toluene and 0.3 parts by weight of benzoyl peroxide are placed in a reaction vessel, and the air in the reaction vessel is replaced with nitrogen gas, followed by stirring. The reaction solution was heated to 70 ° C. in a nitrogen atmosphere and allowed to react for 10 hours. After the reaction, the mixture was diluted with ethyl acetate to obtain a (meth) acrylic polymer solution having a solid content of 25% by weight.

(Polymer solution 5)

65 parts by weight of n-butyl acrylate, 30 parts by weight of methyl methacrylate, 5 parts by weight of acrylamide, 100 parts by weight of toluene, 2 parts by weight of azobisisobutyronitrile and 2 parts by weight of lauryl mercaptan in a reaction vessel, After replacing the air in this reaction container with nitrogen gas, this reaction solution was heated up at 110 degreeC in nitrogen atmosphere under stirring, and it was made to react for 6 hours. After the reaction, the mixture was diluted with toluene to obtain a (meth) acrylic polymer solution having a solid content of 40% by weight.

(Polymer solution 6)

65 parts by weight of n-butyl acrylate, 30 parts by weight of methyl methacrylate, 5 parts by weight of acrylamide, 100 parts by weight of toluene and 2 parts by weight of azobisisobutyronitrile were placed in a reaction vessel, and the air in the reaction vessel was nitrogen gas. Subsequently, the reaction solution was heated to 110 ° C in a nitrogen atmosphere under stirring to react for 6 hours. After the reaction, the mixture was diluted with toluene to obtain a (meth) acrylic polymer solution having a solid content of 40% by weight.

(Polymer solution 7)

52.5 parts by weight of methoxyethyl acrylate, 47 parts by weight of isobutyl methacrylate, 0.5 part by weight of 2-hydroxyethyl acrylate, 100 parts by weight of toluene, 3 parts by weight of benzoyl peroxide and 3 parts by weight of alpha-methylstyrene dimer After replacing the air in this reaction container with nitrogen gas, this reaction solution was heated up to 110 degreeC in nitrogen atmosphere under stirring, and it was made to react for 6 hours. After the reaction, the mixture was diluted with toluene to obtain a (meth) acrylic polymer solution having a solid content of 40% by weight.

(Polymer solution 8)

48 parts by weight of methoxyethyl acrylate, 47 parts by weight of isobutyl methacrylate, 5 parts by weight of 2-hydroxyethyl acrylate, 100 parts by weight of toluene, 3 parts by weight of benzoyl peroxide and 3 parts by weight of alpha-methylstyrene dimer After replacing the air in this reaction container with nitrogen gas, this reaction solution was heated up to 110 degreeC in nitrogen atmosphere under stirring, and it was made to react for 6 hours. After the reaction, the mixture was diluted with toluene to obtain a (meth) acrylic polymer solution having a solid content of 40% by weight.

(Polymer Solution 9)

90 parts by weight of n-butyl acrylate, 10 parts by weight of benzyl acrylate, 100 parts by weight of toluene, 2 parts by weight of azobisisobutyronitrile and 2 parts by weight of lauryl mercaptan are placed in a reaction vessel, and the air in the reaction vessel is nitrogen After substituting with gas, the reaction solution was heated to 110 ° C. in a nitrogen atmosphere under stirring to react for 6 hours. After the reaction, the mixture was diluted with toluene to obtain a (meth) acrylic polymer solution having a solid content of 40% by weight.

The weight average molecular weight (Mw) according to the styrene conversion of each polymer in the polymer solution was determined from gel permeation chromatography (GPC). The measurement conditions are as follows.

Device name: Tosso Co., Ltd., HLC-8120

Column: Tosso Co., Ltd., G7000HXL 7.8 mmID x 30 cm1

GMHXL 7.8 mmID x 30 cm2 pieces

G2500HXL 7.8 mmID x 30 cm1 pcs

Sample concentration: diluted with tetrahydrofuran to 1.5 mg / ml

Mobile phase solvent: tetrahydrofuran

Flow rate: 1.0 ml / min

Column temperature: 40 ℃

The results are shown in Table 1.

Example 1

The polymer solution 1 and the polymer solution 5 are mixed so as to have a solid content ratio of 100 parts by weight / 150 parts by weight, and as a polyfunctional compound, 0.02 part by weight of an epoxy compound (trade name: Tetrado X, manufactured by Sangas Chemical Co., Ltd.) is added thereto. It stirred well, and obtained the adhesive solution for polarizing plates.

The ratio of the functional group amount reactive to the polyfunctional compound is polymer solution 5 / polymer solution 1 = 0% by weight.

The adhesive solution for polarizing plates thus obtained was applied to a release film made of polyester and then dried. At this time, it adjusted so that the coating thickness after drying might be 25um.

Next, the adhesive applied on this release film was transferred onto a 200 um polarizing film, and aged for 7 days at a temperature of 23 ° C. and a humidity of 65% to obtain a polarizing plate of the present invention.

The polarizing plate provided with the pressure-sensitive adhesive layer was cut at 60 mm x 100 mm so that the absorption axis was 45 ° with respect to the long side of the polarizing plate, and the polarizing plate was held at 50 ° C. on one side of the glass plate for 20 minutes under a pressure of 5 kg / cm ² . Adhesion.

Thus, the obtained sample was left to stand for 500 hours at 100 degreeC, 80 degreeC, and 90% of conditions, and visually observed and evaluated the state of foaming and falling off. The results are shown in Table 2.

Similarly, the prepared sample was arrange | positioned so that an absorption axis might go straight on both surfaces of a glass plate, and it hold | maintained for 20 minutes on 50 degreeC and the pressure of 5 kg / cm <^2> , and adhere | attached.

The sample thus obtained was left to stand for 500 hours under conditions of 100 ° C., and the state of generation of color spots was visually observed and evaluated, and the distance at which the bonding position was shifted from the long side of the polarizing plate was measured by Nonius (Nogis). The results are shown in Table 2.

Example 2

The polymer solution 2 and the polymer solution 7 were mixed so as to have a solid content ratio of 100 parts by weight / 25 parts by weight, and as a polyfunctional compound, 1.0 parts by weight of a polyisocyanate compound (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) It added and stirred well, and obtained the adhesive solution for polarizing plates.

The ratio of functional group amount reactive to the polyfunctional compound is polymer solution 7 / polymer solution 2 = 12.5 wt%.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Example 3

The polymer solution 2 and the polymer solution 9 are mixed so as to have a solid content ratio of 100 parts by weight / 100 parts by weight, and a polyisocyanate compound (trade name: Coronate HL, manufactured by Nippon Polyurethane Co., Ltd.) as a polyfunctional compound. It added and stirred well, and obtained the adhesive solution for polarizing plates.

The ratio of functional group amount reactive to the polyfunctional compound is polymer solution 9 / polymer solution 2 = 0% by weight.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Example 4

The polymer solution 1 and the polymer solution 9 were mixed so as to have a solid content ratio of 100 parts by weight / 25 parts by weight, and 0.22 parts by weight of the epoxy compound used in Example 1 as a polyfunctional compound was added thereto and stirred well to obtain an adhesive solution for a polarizing plate. .

The ratio of the functional group amount reactive to the polyfunctional compound is polymer solution 9 / polymer solution 1 = 0% by weight.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Comparative Example 1

The polymer solution 1 and the polymer solution 5 were mixed so as to have a solid content ratio of 100 parts by weight / 10 parts by weight, and 0.22 parts by weight of the epoxy-based compound solids used in Example 1 as the polyfunctional compound was added thereto and stirred well to prepare a pressure-sensitive adhesive solution for polarizing plates. Got it.

The ratio of the functional group amount reactive to the polyfunctional compound is polymer solution 5 / polymer solution 1 = 0% by weight.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Comparative Example 2

The polymer solution 2 and the polymer solution 9 were mixed so as to have a solid content ratio of 100 parts by weight / 250 parts by weight, and 0.04 parts by weight of the polyisocyanate compound solids used in Example 3 as the polyfunctional compound was added thereto, followed by stirring well to prepare a pressure-sensitive adhesive solution for a polarizing plate. Got.

The ratio of functional group amount reactive to the polyfunctional compound is polymer solution 9 / polymer solution 2 = 0% by weight.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Comparative Example 3

The polymer solution 1 and the polymer solution 6 were mixed so as to have a solid content ratio of 100 parts by weight / 150 parts by weight, and 0.02 parts by weight of the epoxy-based compound solids used in Example 1 as the polyfunctional compound was added thereto and stirred well to prepare a pressure-sensitive adhesive solution for a polarizing plate. Got it.

The ratio of the functional group amount reactive to the polyfunctional compound is polymer solution 6 / polymer solution 1 = 0% by weight.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Comparative Example 4

The polymer solution 4 and the polymer solution 5 were mixed so as to have a solid content ratio of 100 parts by weight / 150 parts by weight, and the mixture was stirred well with 0.04 parts by weight of the epoxy-based compound solids used in Example 1 as the polyfunctional compound to prepare a pressure-sensitive adhesive solution for a polarizing plate. Got it.

The ratio of the functional group amount reactive to the polyfunctional compound is polymer solution 5 / polymer solution 4 = 0% by weight.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Comparative Example 5

The polymer solution 2 and the polymer solution 7 were mixed so as to have a solid content ratio of 100 parts by weight / 40 parts by weight, and 1.0 parts by weight of the polyisocyanate compound solids used in Example 2 as the polyfunctional compound was added thereto, followed by stirring well to prepare a pressure-sensitive adhesive solution for a polarizing plate. Got.

The ratio of the functional group amount reactive to the polyfunctional compound is polymer solution 7 / polymer solution 2 = 20 wt%.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Comparative Example 6

The polymer solution 2 and the polymer solution 8 were mixed so as to have a solid content ratio of 100 parts by weight / 20 parts by weight, and 1.0 parts by weight of the polyisocyanate compound solids used in Example 2 as the polyfunctional compound was added thereto, followed by stirring well to prepare a pressure-sensitive adhesive solution for a polarizing plate. Got.

The proportion of functional groups having reactivity to the polyfunctional compound is polymer solution 8 / polymer solution 2 = 100% by weight.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Comparative Example 7

The polymer solution 2 and the polymer solution 3 were mixed so as to have a solid content ratio of 100 parts by weight / 100 parts by weight, and to the mixture, 0.04 parts by weight of the polyisocyanate compound solids used in Example 3 as a polyfunctional compound was added and stirred well to prepare a pressure-sensitive adhesive solution for a polarizing plate. Got.

The ratio of the functional group amount reactive to the polyfunctional compound is polymer solution 3 / polymer solution 2 = 0% by weight.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

Comparative Example 8

0.02 parts by weight of the epoxy compound solids used in Example 1 as a polyfunctional compound was added to 100 parts by weight of the solid content of the polymer solution 1, and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The polarizing plate in which the adhesive layer was provided similarly to Example 1 using the adhesive for polarizing plates obtained in this way was prepared.

About the polarizing plate, the generation | occurrence | production state of foaming and dropping was observed similarly to Example 1. Moreover, the generation | occurrence | production state of the color stain was observed and the distance which the adhesion position shifted from the long side of a polarizing plate was measured. These results are shown in Table 2.

In the said Example and the comparative example, the compounding ratio of a polymer solution is shown in Table 3.

TABLE 1

Monomer compounding (weight part) Weight average molecular weight BA AA BzA 2HEA MMA AM iBMA MEA Polymer solution 1 Polymer solution 2 Polymer solution 3 Polymer solution 4 Polymer solution 5 Polymer solution 6 Polymer solution 7 Polymer solution 8 Polymer solution 9 958990956565--90 5--5 ----- -1010 ----- 10 -1 ---- 0.55- ---- 3030 --- ---- 55 --- ------ 4747- ------ 52.548- 15012012080150.80.91.2

Note) In Table 1 above, the symbols described have the following meanings.

Butyl acrylate: BA

Acrylic acid: AA

Benzylacrylate: BzA

2-hydroxyethylacrylate: 2HEA

Methyl methacrylate: MMA

Acrylamide: AM

Isobutyl methacrylate: iBMA

Methoxyethylacrylate: MEA

TABLE 2

Heat resistance 100 ℃ x 500 hr Heat and humidity resistance 80 ℃, 90% x 500 hr Optical Properties 100 ℃ x 500 hr firing Peeling firing Peeling A displaced distance Stain Example 1 none none none none 1.2 mm none Example 2 none none none none 0.8 mm none Example 3 none none none none 1.0 mm none Example 4 none none none none 0.7 mm none Comparative Example 1 none none none none 0.4 mm has exist Comparative Example 2 none has exist none has exist Inmeasurement Inmeasurement Comparative Example 3 has exist has exist none has exist Inmeasurement Inmeasurement Comparative Example 4 has exist none none none 1.2 mm none Comparative Example 5 has exist none has exist none 1.0 mm none Comparative Example 6 has exist none has exist none 0.9 mm none Comparative Example 7 none none none none 0.3 mm has exist Comparative Example 8 none none none none 0.2 mm has exist

TABLE 3

Polymer solution Functional group distribution rate (% by weight) One 2 3 4 5 6 7 8 9 Example 1 100 - - - 150 - - - - 0 Example 2 - 100 - - - - 25 - - 12.5 Example 3 - 100 - - - - - - 100 0 Example 4 100 - - - - - - - 100 0 Comparative Example 1 100 - - - 15 - - - - 0 Comparative Example 2 - 100 - - - - - - 250 0 Comparative Example 3 100 - - - - 150 - - - 0 Comparative Example 4 - - - 100 150 - - - - 0 Comparative Example 5 - 100 - - - - 40 - - 20 Comparative Example 6 - 100 - - - - - 20 - 100 Comparative Example 7 - 100 100 - - - - - - 0 Comparative Example 8 100 - - - - - - - - -

The adhesive for polarizing plates of this invention consists of a weight average molecular weight 1 million or more high molecular weight (meth) acrylic-type copolymer, the low molecular weight (meth) acrylic-type (co) polymer of a weight average molecular weight of 30,000 or less, and a polyfunctional compound, and this polyfunctional compound Is mainly combined with a high molecular weight (meth) acrylic copolymer to form a three-dimensional crosslinked structure. On the other hand, the low molecular weight (meth) acrylic-based (co) polymer is uniquely present in the three-dimensional crosslinked structure formed as described above because it is difficult to form a three-dimensional crosslinked structure even if it does not or does not react with the multifunctional compound. Thus, the pressure-sensitive adhesive layer formed by the three-dimensional crosslinked structure formed from the polyfunctional compound and the high molecular weight (meth) acrylic copolymer and the low molecular weight (meth) acrylic (co) polymer uniquely present in the three-dimensional crosslinked structure has a temperature. And it is possible to follow the dimensional change of a polarizing plate resulting from humidity.

Therefore, by adhering the polarizing film to the retardation plate or the substrate of the liquid crystal element using the pressure-sensitive adhesive of the present invention, foaming does not occur in the pressure-sensitive adhesive layer even when repeatedly used under high temperature and high humidity, and further, interfacial peeling or the like occurs. In addition, it is possible to form a liquid crystal device having less color specks in the peripheral and central portions.

Claims (4)

(A) A repeating unit derived from the (meth) acrylic acid ester is a main repeating unit, and a repeating unit derived from a functional group-containing monomer having reactivity with the multifunctional compound (C) is copolymerized in an amount of 0.5 to 20% by weight A high molecular weight (meth) acrylic copolymer having a weight average molecular weight of 1 million or more, To 100 parts by weight of the high molecular weight (meth) acrylic copolymer, (B) A low molecular weight (meth) acrylic (co) polymer having a weight average molecular weight of 30,000 or less, wherein the repeating unit derived from the functional group-containing monomer reactive with the multifunctional compound (C) is polymerized in an amount of 0 to 10% by weight. 20 to 200 parts by weight, (C) A multi-tube having at least two functional groups in the molecule which can be combined with the high molecular weight (meth) acrylic copolymer (A) and / or the low molecular weight (meth) acrylic (co) polymer (B) to form a crosslinked structure. Comprised of 0.005 to 5 parts by weight of the functional compound, The repeating unit derived from the functional group containing monomer which is reactive with respect to the polyfunctional compound (C) copolymerized with the said high molecular weight (meth) acrylic-type copolymer (A) and the low molecular weight (meth) acrylic-type (co) polymer (B) Pressure-sensitive adhesive for polarizing plate, which is contained in a high molecular weight (meth) acrylic copolymer (A) and a low molecular weight (meth) acrylic (co) polymer (B) at a functional group distribution ratio represented by the following formula; Functional group partition ratio = [Multifunctional compound in the monomer equivalent weight / high molecular weight (meth) acrylic copolymer of a repeating unit derived from a functional group-containing monomer having reactivity with the multifunctional compound (C) in a low molecular weight (meth) acrylic copolymer ( Monomer equivalent weight of repeating unit derived from a functional group-containing monomer having reactivity with respect to C)] X 100 = 0 to 15% by weight. The weight average molecular weight of the said high molecular weight (meth) acrylic-type copolymer (A) exists in the range of 1 million-2 million, and the weight average molecular weight of the said low molecular weight (meth) acrylic-type (co) polymer (B). It exists in the range of 1000-20000, The adhesive for polarizing plates. (A) A repeating unit derived from the (meth) acrylic acid ester is a main repeating unit, and a repeating unit derived from a functional group-containing monomer having reactivity with the multifunctional compound (C) is copolymerized in an amount of 0.5 to 20% by weight A high molecular weight (meth) acrylic copolymer having a weight average molecular weight of 1 million or more, To 100 parts by weight of the high molecular weight (meth) acrylic copolymer, (B) A low molecular weight (meth) acrylic (co) polymer having a weight average molecular weight of 30,000 or less, wherein the repeating unit derived from the functional group-containing monomer reactive with the multifunctional compound (C) is polymerized in an amount of 0 to 10% by weight. 20 to 200 parts by weight, (C) A multi-tube having at least two functional groups in the molecule which can be combined with the high molecular weight (meth) acrylic copolymer (A) and / or the low molecular weight (meth) acrylic (co) polymer (B) to form a crosslinked structure. Comprised of 0.005 to 5 parts by weight of the functional compound, The repeating unit derived from the functional group containing monomer which is reactive with respect to the polyfunctional compound (C) copolymerized with the said high molecular weight (meth) acrylic-type copolymer (A) and the low molecular weight (meth) acrylic-type (co) polymer (B) The pressure-sensitive adhesive layer made of a pressure-sensitive adhesive, characterized in that contained in a high molecular weight (meth) acrylic copolymer (A) and a low molecular weight (meth) acrylic (co) polymer (B) at a functional group distribution ratio represented by the following formula: A polarizing plate formed on at least one surface; Functional group partition ratio = [Multifunctional compound in the monomer equivalent weight / high molecular weight (meth) acrylic copolymer of a repeating unit derived from a functional group-containing monomer having reactivity with the multifunctional compound (C) in a low molecular weight (meth) acrylic copolymer ( Monomer equivalent weight of repeating unit derived from a functional group-containing monomer having reactivity with respect to C)] X 100 = 0 to 15% by weight. The weight average molecular weight of the high molecular weight (meth) acrylic copolymer (A) is in the range of 1 million to 2 million, and the weight average molecular weight of the low molecular weight (meth) acrylic (co) polymer (B). It exists in the range of 1000-20000, The polarizing plate characterized by the above-mentioned.