JPH10279907A - Pressure sensitive adhesive composition for polarizing plate and polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject adhesive composition capable of forming an adhesive layer following changes in the dimension of a polarizing plate and ensuring avoiding development of uneven color in liquid crystal elements. SOLUTION: This adhesive composition for polarizing plates comprises 100 pts.wt. of a high molecular weight (meth)acrylic copolymer, having a weight average molecular weight of >=10<6> , made from an alkyl (meth)acrylate and 5-20 wt.% of a polymerizable monomer having functionality for a cross-linking agent, 20-200 pts.wt. of a low molecular weight (meth)acrylic (co)polymer having a weight average molecular weight of <=30000, and 0.005-5 pts.wt. of a multi- functional compound having at least 2 intramolecular functional groups capable of forming a cross-linked structure. The functional group distribution rate expressed by the weight of the functional group in the low molecular weight (meth)acrylic (co)polymer/the weight of those in the high molecular weight (meth)acrylic copolymer is within the range of 0-15%. The objective polarizing plate has adhesive layer formed from this adhesive composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for attaching a polarizing plate used for a liquid crystal element or the like to a retardation plate or a substrate, and a polarizing plate having a layer made of the adhesive.

[0002]

2. Description of the Related Art A liquid crystal element has a structure in which a liquid crystal component oriented in a predetermined direction is sandwiched between two substrates. On the surface of this substrate, a polarizing plate or a laminate of a polarizing plate and a retardation plate is provided. The body is stuck. Such a liquid crystal element has been used in a wide range of fields as a display device.

[0003] Since liquid crystal elements are suitable for reducing the weight and thickness of the device, in recent years this liquid crystal element has been used as a display device for vehicles, outdoor instruments, displays of personal computers, and wall-mounted televisions. Has become
Accordingly, the use environment has become very severe. Under such severe conditions, the dimensional change of the polarizing plate occurs,
With this dimensional change, foaming and peeling are likely to occur.
The pressure-sensitive adhesive for attaching a polarizing plate to a retardation plate or a substrate has been improved so as to increase the molecular weight or the degree of crosslinking so that the pressure-sensitive adhesive layer can be used 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 use under severe conditions is intended to suppress the dimensional change of the polarizing plate with the pressure-sensitive adhesive. Although a certain dimensional change or a dimensional change for a certain period of time can be suppressed, the internal stress caused by the dimensional change of the polarizing plate over a long period of time concentrates on the peripheral portion of the polarizing plate, and the peripheral portion of the liquid crystal element is located at the center. Color unevenness occurs on the surface of the liquid crystal element, such as being brighter or darker.

Japanese Patent Application Laid-Open No. Sho 60-207101 roughly discloses (A) an alkyl (meth) acrylate copolymer having a reactive functional group, and (B) an alkyl (meth) acrylate having no functional group ( (Co) polymers and (C)
A polyfunctional compound having at least two functional groups capable of reacting with the reactive functional group, comprising the above (A) and (B) in a ratio of 1: 4
There is disclosed an invention of a polarizing plate in which a pressure-sensitive adhesive layer containing at a ratio of 4: 1 is laminated on at least one surface of a polarizing film.

[0006] By adopting the above structure, the cohesive force, adhesive force and viscoelasticity of the pressure-sensitive adhesive are excellent and well balanced, and free functional groups remain due to crosslinking. The publication states that the quality of the polarizing film is stable and that no bubbles are generated between the polarizing film and the substrate even under high-temperature and high-humidity conditions, and that no interface peeling occurs.

However, in the invention described in this publication, (A) an alkyl (meth) acrylate copolymer having a reactive functional group and (B) an alkyl (meth) acrylate having no functional group (copolymer) The polymer is produced under similar reaction conditions, and the (A) alkyl (meth) acrylate copolymer having a reactive functional group and the (B) alkyl (meth) acrylate having no functional group ( The (co) polymers are considered to have approximately the same molecular weight. That is, this publication has different molecular weights
The technical idea of using (A) an alkyl (meth) acrylate copolymer having a reactive functional group and (B) an alkyl (meth) acrylate (co) polymer having no functional group is not disclosed. For this reason, even if the adhesive described in this publication is used, the adhesive layer cannot follow the dimensional change of the polarizing plate.

[0008] Further, Patent Publication No. 2549388 discloses that “the surface of a polarizing plate has an alkyl group having 1 to 12 carbon atoms.
A polarizing plate provided with a pressure-sensitive adhesive layer comprising an acrylic polymer having an alkyl ester of acrylic acid or methacrylic acid as a main component, wherein the pressure-sensitive adhesive layer has a weight average molecular weight of 100,000 or less. A pressure-sensitive adhesive-type polarizing plate comprising an acrylic polymer containing 15% by weight or less of a polymer component and 10% by weight or more of a polymer component having a weight average molecular weight of 1,000,000 or more. Is disclosed. The pressure-sensitive adhesive layer is cross-linked, and the cross-linked pressure-sensitive adhesive layer contains 15% by weight or less of an uncrosslinked polymer component having a weight average molecular weight of 100,000 or less based on the total polymer weight. Is disclosed.

In the invention described in this publication, the content of the high-molecular-weight polymer having a weight-average molecular weight of 1,000,000 or more in the pressure-sensitive adhesive layer is 10% by weight or more. Conversely, the content of the low molecular weight polymer having a weight average molecular weight of 100,000 or less is 15% by weight or less,
In the present invention, an attempt is made to lower the content of the low molecular weight polymer. According to the study of the present inventor, when the content of the low molecular weight polymer is low as described above, the followability of the pressure-sensitive adhesive layer to the dimensional change of the polarizing plate is low, and the internal stress generated within a certain range is resisted. However, the internal stress that occurs repeatedly over a long period of time concentrates on the periphery of the polarizing plate, and the periphery of the liquid crystal element becomes brighter or darker than the central part, resulting in uneven color on the surface of the liquid crystal element. Occur. That is, in the invention described in this publication, the use of a large amount of a high molecular weight polymer allows the pressure-sensitive adhesive to withstand internal stress caused by long-term use. Accordingly, the invention disclosed in this publication includes a polarizing plate that absorbs internal stress generated between a bonded polarizing plate and a liquid crystal cell substrate with an adhesive layer and absorbs internal stress generated by long-term use. There is no technical idea to correct internal distortion between the plate and the liquid crystal cell substrate. Therefore, even if the adhesive described in this publication is used, it is not possible to form an adhesive layer having a followability corresponding to the dimensional change of the polarizing plate.

[0010]

The object of the present invention is to follow the dimensional change occurring in a polarizing plate, and it does not foam even if it is used repeatedly for a long period of time under high temperature and high humidity conditions, and the interface peels off. A pressure-sensitive adhesive for a polarizing plate capable of forming a liquid crystal element having no color unevenness between the peripheral portion and the central portion, and a polarizing plate having a layer made of the pressure-sensitive adhesive formed on at least one surface. It is intended to be.

[0011]

SUMMARY OF THE INVENTION The pressure-sensitive adhesive for polarizing plate of the present invention comprises (A) a repeating unit derived from a (meth) acrylate ester as a main repeating unit, and has reactivity with a polyfunctional compound (C). A high molecular weight (meth) acrylic copolymer having a repeating unit derived from a functional group-containing monomer in an amount of 0.5 to 20% by weight and a weight average molecular weight of 1,000,000 or more; ) Based on 100 parts by weight of the acrylic copolymer, (B) a repeating unit derived from a functional group-containing monomer reactive to the polyfunctional compound (C) is polymerized in an amount of 0 to 10% by weight. Low molecular weight (meth) acrylic (co) polymer 20 to 20 having a weight average molecular weight of 30,000 or less
0 parts by weight and (C) the high molecular weight (meth) acrylic copolymer (A) and / or the low molecular weight (meth) acrylic (co) polymer (B) to form a crosslinked structure 0.005 to 5 parts by weight of a polyfunctional compound having at least two functional groups in the molecule,
Polyfunctional compound copolymerized with acrylic copolymer (A) and low molecular weight (meth) acrylic (co) polymer (B)
The repeating unit derived from the functional group-containing monomer having reactivity with (C) has a high molecular weight (meth) acrylic copolymer (A) and a low molecular weight ( It is characterized by being contained in a (meth) acrylic (co) polymer (B).

Functional group distribution ratio = [weight in terms of monomer of a repeating unit derived from a functional group-containing monomer having reactivity with the polyfunctional compound (C) in the low molecular weight (meth) acrylic copolymer / Weight in monomer equivalent of a repeating unit derived from a functional group-containing monomer reactive with the polyfunctional compound (C) in the high molecular weight (meth) acrylic copolymer] × 100 = 0 to 15% by weight.

Further, the polarizing plate of the present invention comprises (A) a repeating unit derived from a (meth) acrylate ester as a main repeating unit, and contains a functional group having a reactivity with the polyfunctional compound (C). The repeating unit derived from the monomer is 0.5
A high-molecular-weight (meth) acrylic copolymer having a weight average molecular weight of 1,000,000 or more while copolymerizing in an amount of
With respect to 100 parts by weight of the high molecular weight (meth) acrylic copolymer, the repeating unit derived from the functional group-containing monomer (B) having reactivity with the polyfunctional compound (C) is 0.
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 polymerized in an amount of 10 to 10% by weight, and (C) the high molecular weight (meth) acrylic copolymer
(A) and / or low molecular weight (meth) acrylic (co)
A polyfunctional compound having at least two functional groups in the molecule capable of forming a crosslinked structure by bonding to the polymer (B) 0.00
5 to 5 parts by weight of a polyfunctional compound copolymerized with the high molecular weight (meth) acrylic copolymer (A) and the low molecular weight (meth) acrylic (co) polymer (B) ( The repeating unit derived from the functional group-containing monomer reactive to C) has a high molecular weight (meth) acrylic copolymer (A) and a low molecular weight (meth) having a functional group distribution represented by the above formula. A) a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive contained in the acrylic (co) polymer (B) is formed on at least one surface of the polarizing plate;

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 1,000,000 or more is used as the (meth) acrylic copolymer reacting with the polyfunctional compound. Two types of low-molecular-weight (meth) acrylic (co) polymers having a weight average molecular weight of 30,000 or less as (meth) acrylic (co) polymers having no or little reactivity with the polyfunctional compound while being used (Meth) acrylic polymers having different molecular weights, and the amount of functional groups having reactivity with polyfunctional compounds is lower than that of high molecular weight (meth) acrylic copolymers. Since the amount of the (co) polymer is smaller, the low molecular weight (meth) acrylic copolymer does not bond to the polyfunctional compound, or does not easily form a three-dimensional crosslinked structure even when bonded. Therefore, by using the pressure-sensitive adhesive having the composition of the present invention, a three-dimensional crosslinked structure is formed by a high molecular weight (meth) acrylic copolymer and a polyfunctional compound, and a low molecular weight (meth ) An acrylic (co) polymer is present.

In the pressure-sensitive adhesive for polarizing plate of the present invention having such a structure, foaming and peeling generated under high-temperature and high-humidity conditions are prevented by the formed three-dimensional structure, and the dimensional change of the polarizing plate is caused. Adhesive property that internal stress is absorbed by the low molecular weight (meth) acrylic (co) polymer present in the three-dimensional crosslinked structure, and changes following the change in the shape of the polarizing plate with changes in temperature or humidity. It is given to the agent layer.

Accordingly, in the polarizing film adhered to the substrate or the retardation plate with the adhesive, the internal stress generated by the change in temperature, the change in humidity, etc. is absorbed by the adhesive layer. No color unevenness such as lighter or darker than the central portion occurs, and no foaming or peeling occurs.

[0017]

Next, the pressure-sensitive adhesive for a polarizing plate of the present invention and a polarizing plate having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive will be described in detail.

The pressure-sensitive adhesive for polarizing plate of the present invention contains a high molecular weight (meth) acrylic copolymer, a low molecular weight (meth) acrylic (co) polymer, and a polyfunctional compound. . The high molecular weight (meth) acrylic copolymer is (meth)
It is a copolymer of an acrylic ester as a main component, and a (meth) acrylic ester and a functional group-containing monomer reactive with the polyfunctional compound (C). The (meth) acrylic acid ester forming this high molecular weight (meth) acrylic copolymer includes 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) acrylate, cyclohexyl (meth) acrylate, benzyl Examples thereof include (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, and phenoxyethyl (meth) acrylate. These can be used alone or in combination.

Examples of the functional group-containing monomer reactive to the polyfunctional compound include (meth) acrylic acid, β-carboxyethyl acrylate, itaconic acid, crotonic acid, maleic acid, maleic anhydride and Monomers containing a carboxyl group such as butyl maleate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, chloro-2-hydroxypropyl (meth) acrylate, Hydroxyl-containing monomers such as diethylene glycol mono (meth) acrylate and allyl alcohol, aminomethyl (meth) acrylate, dimethylaminomethyl (meth) acrylate,
Monomers containing an amino group such as dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate and vinylpyridine; monomers containing an epoxy group such as glycidyl (meth) acrylate; and acetoacetoxyethyl (meth) acrylate Examples of the monomer include an acetoacetyl group. These can be used alone or in combination.

Among these, a monomer containing a carboxyl group and a monomer containing a hydroxyl group are preferred.
The high molecular weight (meth) acrylic copolymer is 80 to 99.
5% by weight, preferably 90-99.5% by weight of alkyl
It is a copolymer of (meth) acrylic acid ester and 0.5 to 20% by weight, preferably 0.5 to 15% by weight of a functional group-containing monomer having reactivity with a polyfunctional compound.

By co-polymerizing the alkyl (meth) acrylate and a polymerizable monomer having reactivity to the polyfunctional compound in the above-mentioned amount, the compound is bonded to the polyfunctional compound to obtain a good adhesive property. Can be formed.

The weight average molecular weight of the high molecular weight (meth) acrylic copolymer constituting the pressure-sensitive adhesive composition of the present invention is as follows:
It is necessary to be 1,000,000 or more, and it is more preferable that it is in the range of 1,000,000 to 2,000,000. By using such a high molecular weight (meth) acrylic copolymer, good adhesion between the substrate and the polarizing plate or between the retardation plate and the polarizing plate can be ensured, and foaming and peeling can be prevented. it can.

The high molecular weight (meth) acrylic copolymer in the present invention is a copolymer of a (meth) acrylic ester and a polymerizable monomer having reactivity to a polyfunctional compound. Other monomers may be copolymerized with the high molecular weight (meth) acrylic copolymer as long as the properties of the high molecular weight (meth) acrylic copolymer are not impaired.

Examples of other monomers that can be copolymerized here include vinyl acetate, styrene, methylstyrene, vinyltoluene, acrylonitrile, (meth) acrylamide and N-methylacrylamide. The polymerization amount of this monomer is usually 0 to 30% by weight, preferably 100% by weight, based on the total amount of (meth) acrylic acid ester and the polymerizable monomer having reactivity to the polyfunctional compound. 0 to 15% by weight.

The pressure-sensitive adhesive for a polarizing plate of the present invention contains a low molecular weight (meth) acrylic (co) polymer. This low molecular weight (meth) acrylic (co) polymer is a polymer having no or little reactivity with a polyfunctional compound, and a functional group having reactivity with the polyfunctional compound. Is lower than the amount of the repeating unit derived from the monomer having a functional group present in the high molecular weight (meth) acrylic copolymer. That is, this low molecular weight (meth) acrylic (co) polymer has a repeating unit derived from a (meth) acrylate ester as a main repeating unit, and is composed of a functional group-containing monomer having reactivity with a polyfunctional compound. It is a (co) polymer that does not contain any repeating unit or has a very small content. Further, this copolymer may be copolymerized with another monomer.

(Meth) acrylic acid esters used in the production of low molecular weight (meth) acrylic (co) polymers,
As the functional group-containing monomer and the other monomer having reactivity with the polyfunctional compound, those described for the high molecular weight (meth) acrylic copolymer are usually used. The weight average molecular weight of the low molecular weight (meth) acrylic (co) polymer needs to be 30,000 or less, and more preferably in the range of 1,000 to 20,000.
By using a (meth) acrylic (co) polymer having such a molecular weight, the pressure-sensitive adhesive composition of the present invention has good followability of the pressure-sensitive adhesive layer to dimensional changes due to temperature and humidity of the polarizing plate, The liquid crystal element is used under high temperature and high humidity conditions,
Even if the dimensions of the polarizing plate change, the pressure-sensitive adhesive layer fluctuates following the dimensional change, so that there is no difference between the brightness at the periphery and the brightness at the center of the liquid crystal element, and color unevenness occurs. No longer.

This low molecular weight (meth) acrylic (co)
The 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.
Used in parts by weight. If the amount is less than 20 parts by weight, the pressure-sensitive adhesive layer cannot follow the dimensional change of the polarizing plate sufficiently, and the color unevenness cannot be suppressed. If the amount exceeds 200 parts by weight, the adhesive under high temperature and high humidity is used. The properties are reduced, and peeling occurs.

Further, in the present invention, when the high molecular weight (meth) acrylic copolymer and the low molecular weight (meth) acrylic (co) polymer are mixed at the above ratio, each of the two The functional group partition ratio, which is the ratio of the reduced weight of the monomer of the repeating unit derived from the functional group-containing monomer having reactivity to the polyfunctional compound (C), in the polymer of the present invention is within a specific range. is required.

This functional group dispersion is expressed by the following equation. Functional group partitioning ratio = [weight in monomer equivalent of a repeating unit derived from a functional group-containing monomer reactive to the polyfunctional compound (C) in the low molecular weight (meth) acrylic copolymer / high molecular weight ( Weight in terms of monomer of a repeating unit derived from a functional group-containing monomer having reactivity with the polyfunctional compound (C) in the (meth) acrylic copolymer] × 100.

In the present invention, the functional group distribution must be in the range of 0 to 15% by weight, and more preferably in the range of 0 to 10% by weight. This functional group distribution ratio indicates a method of forming a cross-linked structure formed by a cross-linking agent (C) (polyfunctional compound) described later, and the low-molecular-weight (meth) acrylic (co) polymer has: 15% by weight of a repeating unit derived from a functional group-containing monomer reactive to the polyfunctional compound (C) forming the high molecular weight (meth) acrylic copolymer (A)
Hereafter, preferably, it has a repeating unit derived from a monomer having a functional group in an amount of not more than 10% by weight, or does not have this repeating unit. As described above, the low molecular weight (meth) acrylic (co) polymer has no or does not have a repeating unit derived from a functional group-containing monomer having reactivity with the polyfunctional compound (C). However, since the number thereof is small, a cross-linked structure is not formed or hardly formed in the low molecular weight (meth) acrylic (co) polymer. Therefore, this low molecular weight (meth) acrylic (co) polymer (B) is It can move to some extent freely in the three-dimensional crosslinked structure formed by the high molecular weight (meth) acrylic copolymer (A) and the polyfunctional compound (C). The basic adhesive strength between the polarizing plate and the liquid crystal cell substrate, etc. is mainly exhibited by the three-dimensionally cross-linked structure. Since this is not absorbed by the three-dimensionally cross-linked structure, internal strain is generated by 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, the low-molecular-weight (meth) acrylic (B) containing the low-molecular-weight (meth) acrylic (co) polymer (B) having a specific weight average molecular weight in the above-mentioned amount and having a functional group distribution within the above-mentioned range. By containing the (co) polymer (B), the adhesive layer formed by the adhesive composition of the present invention has a shape following property corresponding to a change with time of the polarizing plate. By improving the form following ability, color unevenness can be suppressed.

Therefore, when the distribution ratio of the functional group exceeds 15% by weight, the ratio of the reaction between the low molecular weight (meth) acrylic (co) polymer and the polyfunctional compound increases, and the high molecular weight (meth) acrylic Since the amount of the three-dimensional crosslinked structure formed by the copolymer and the polyfunctional compound decreases, foaming occurs under high temperature and high humidity.

The pressure-sensitive adhesive for polarizing plate of the present invention contains a polyfunctional compound as a polyfunctional compound. The functional group of the compound reacts with the reactive functional group of the (meth) acrylic polymer, and has at least two, preferably 2 to 4 functional groups in one molecule. I have.

Examples of such polyfunctional compounds include:
Examples include isocyanate compounds, epoxy compounds, amine compounds, metal chelate compounds, and aziridine compounds.

Examples of isocyanate compounds include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylylene diisocyanate, naphthalene diisocyanate, Examples thereof include phenylmethane triisocyanate, polymethylene polyphenyl isocyanate, and adducts thereof with polyols such as trimethylolpropane.

Examples of epoxy compounds include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol. Diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, diglycidylamine, N, N, N ', N'-tetraglycidyl-m-xylenediamine and 1,3-bis (N, N'-
Diglycidylaminomethyl) cyclohexane and the like.

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

Further, as examples of metal chelate compounds, polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium are distributed in acetylacetone and ethyl acetoacetate. And the like.

Further, examples of aziridine compounds include N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxide), N, N'-toluene-2,4-bis (1-aziridine Carboxamide), triethylene melamine, bisisophthaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N'-hexamethylene-1.6-bis (1-aziridinecarboxide), Mention may be made of trimethylolpropane-tri-β-aziridinylpropionate and tetramethylolmethane-tri-β-aziridinylpropionate.

Such a polyfunctional compound is used in an amount of 100 parts by weight of the high molecular weight (meth) acrylic copolymer.
Usually it is used in an amount of from 0.005 to 5 parts by weight, preferably from 0.01 to 3 parts by weight. By using the polyfunctional compound in such an amount, a suitable three-dimensional crosslinked structure is formed between the polyfunctional compound and the high molecular weight (meth) acrylic copolymer. In addition, these polyfunctional compounds can be used alone or in combination.

High molecular weight (meth) acrylic copolymer and low molecular weight (meth) constituting the pressure-sensitive adhesive for polarizing plate of the present invention
For the production of the acrylic (co) polymer, any known method can be employed.

For example, the high molecular weight (meth) acrylic copolymer is used in an amount of 0.01 to 100 parts by weight of the starting monomer.
1 part by weight of a polymerization initiator (azobisisovitylonitrile,
Azo-based polymerization initiators such as azobiscyclohexanecarbonitrile, peroxides such as benzoyl peroxide and acetyl peroxide, diphenyl ketone, 2-hydroxy-2-methyl-1-
Phenyl-propan-1-one or the like), and is synthesized by a method such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization, and is preferably synthesized by solution polymerization.

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

Also, low molecular weight (meth) acrylic (co)
The polymer is synthesized by a method such as bulk polymerization, solution polymerization, emulsion polymerization, or suspension polymerization, as in the case of the high molecular weight acrylic copolymer, and is preferably synthesized by solution polymerization. However, in order to reduce the weight average molecular weight to 30,000 or less, the amount of the polymerization initiator to be used is set to be about 10 to 100 times that in the case of the high molecular weight acrylic copolymer, and more preferably lauryl mercaptan, n-
Mercaptans such as dodecyl mercaptan, n-octyl mercaptan, chain transfer agents such as α-methylstyrene dimer and limonene are used.

The pressure-sensitive adhesive for polarizing plate of the present invention is obtained by mixing the high molecular weight (meth) acrylic copolymer, the low molecular weight (meth) acrylic (co) polymer and the polyfunctional compound produced as described above. Can be manufactured.

At this time, the low molecular weight (meth) acrylic (co) polymer is used in an amount of 20 to 200 parts by weight, preferably 30 to 150 parts by weight, based on 100 parts by weight of the high molecular weight (meth) acrylic copolymer. Parts and the polyfunctional compound are contained in an amount of 0.005 to 5 parts by weight, preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the high molecular weight (meth) acrylic copolymer.

The pressure-sensitive adhesive for polarizing plate of the present invention comprises a high molecular weight (meth) acrylic copolymer, a low molecular weight (meth) acrylic (co) polymer and a polyfunctional compound as described above. The pressure-sensitive adhesive for a polarizing plate may contain a weathering stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, a silane coupling agent, an inorganic filler, and the like, which are usually added to the pressure-sensitive adhesive.

In the polarizing plate of the present invention, an adhesive layer formed from the above adhesive is laminated on one surface of the polarizing film.
As the polarizing film used in the present invention, a conventionally known polarizing film can be used.

For example, polyvinyl alcohol, polyvinyl formal, polyvinyl acetal and ethylene.
A film obtained by stretching a film made of a polyvinyl alcohol-based resin such as a saponified vinyl acetate copolymer containing a polarizing component such as iodine or a dichroic dye, and a cellulose-based film such as cellulose triacetate. A multilayer film in which a protective film such as a film, a polycarbonate film, and a polyethersulfone film is laminated can be used.

There is no particular limitation on the method of forming the pressure-sensitive adhesive layer on such a polarizing film, and a method of directly applying the above-mentioned pressure-sensitive adhesive to the surface of the polarizing film using a bar coater or the like and drying may be employed. After the adhesive is once applied to the surface of the peelable substrate and dried, the adhesive layer formed on the surface of the peelable substrate is transferred to the surface of the polarizing film,
Then, it is preferable to adopt a method of aging.

The thickness of the pressure-sensitive adhesive layer thus formed is usually 10 to 100 μm in dry thickness, preferably 20 to 50 μm.
It is in the range of μm. It is sufficient that the pressure-sensitive adhesive layer is formed on at least one surface of the polarizing film. Therefore, in the present invention, the pressure-sensitive adhesive layer can be formed on both surfaces of the polarizing film.

Further, the polarizing plate of the present invention may be laminated with a layer having another function such as a protective layer, a reflective layer, and an anti-glare layer.

[0052]

The pressure-sensitive adhesive for polarizing plate of the present invention has a weight average molecular weight of 1,000,000 or more and a high molecular weight (meth) acrylic copolymer, and a low molecular weight (meth) acrylic (co) of 30,000 or less. It is composed of a polymer and a polyfunctional compound, and the polyfunctional compound mainly binds to a high molecular weight (meth) acrylic copolymer to form a three-dimensional crosslinked structure. on the other hand,
The low molecular weight (meth) acrylic (co) polymer does not react with the polyfunctional compound or does not easily form a three-dimensional cross-linked structure even if it reacts. Exists on its own. Thus, 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) The pressure-sensitive adhesive layer made of a polymer can follow the dimensional change of the polarizing plate caused by temperature and humidity.

Therefore, by attaching a polarizing film to a retardation plate or a substrate of a liquid crystal element using the pressure-sensitive adhesive of the present invention, it can be used repeatedly under high temperature and high humidity.
It is possible to form a liquid crystal element without foaming in the pressure-sensitive adhesive layer, without peeling off at the interface, and with less color unevenness between the peripheral portion and the central portion.

[0054]

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 to these examples.

(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 were placed in a reaction vessel, and air in the reaction solution vessel was removed. After purging with nitrogen gas, the reaction solution was heated to 66 ° C. in a nitrogen atmosphere under stirring 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 of ethyl acetate
Parts by weight, and 0.2 parts by weight of azobisisobutyronitrile were put into a reaction vessel, and the air in the reaction solution vessel was replaced with nitrogen gas. 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 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 are put into a reaction vessel, and the reaction solution After replacing the air inside with nitrogen gas, in a nitrogen atmosphere under stirring,
This reaction solution was heated to 66 ° C. 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 0.5 part of benzoyl peroxide.
After placing 3 parts by weight in a reaction vessel and replacing the air in the reactor with nitrogen gas, the reaction solution was heated to 70 ° C. in a nitrogen atmosphere with stirring and reacted for 10 hours. After the reaction, the mixture was diluted with ethyl acetate to give a solid content of 25% by weight of (meth)
An acrylic polymer solution was obtained.

(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 were reacted. The reaction solution was placed in a container, and the air in the reaction solution vessel was replaced with nitrogen gas. Then, the reaction solution was heated to 110 ° C. in a nitrogen atmosphere with stirring, and reacted for 6 hours.
After the reaction, the resultant 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 put into a reaction vessel, and the reaction was carried out. After replacing the air in the solution container with nitrogen gas, the reaction solution was heated to 110 ° C. in a nitrogen atmosphere under stirring and reacted for 6 hours. After the reaction, the resultant 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 of isobutyl methacrylate
Parts by weight, 0.5 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 α-methylstyrene dimer are placed in a reaction vessel. After the reaction, the reaction solution is heated to 110 ° C. in a nitrogen atmosphere with stirring.
And reacted for 6 hours. After the reaction, the resultant 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 α
-Put 3 parts by weight of methyl styrene dimer into a reaction vessel,
After replacing the air in the reaction solution vessel with nitrogen gas, the reaction solution was heated to 110 ° C. in a nitrogen atmosphere with stirring, and reacted for 6 hours. After the reaction, the resultant 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. After replacing the air in the solution vessel with nitrogen gas,
The reaction solution was heated to 110 ° C. in a nitrogen atmosphere under stirring and reacted for 6 hours. After the reaction, the resultant 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) of each polymer in the above polymer solution in terms of styrene was determined by gel permeation chromatography (GPC). The measurement conditions are as follows.

Apparatus name: HLC-8120, manufactured by Tosoh Corporation Column: G7000HXL 7.8 mmID × 30 cm, 1 piece GMHXL 7.8 mmID × 30 cm, 2 pieces G2500HXL 7.8 mmID × 30 cm, 1 piece Sample concentration: 1.5 mg / Ml diluted with tetrahydrofuran Mobile phase solvent: tetrahydrofuran Flow rate: 1.0 ml / min Column temperature: 40 ° C The results are shown in Table 1.

[0066]

Example 1 Polymer solution 1 and polymer solution 5 were mixed at a solid content ratio of 100 parts by weight / 150 parts by weight, and an epoxy-based compound (trade name:
Tetrad X (manufactured by Mitsubishi Gas Chemical Co., Ltd.) (0.02 parts by weight of solid content) was added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is as follows: polymer solution 5 / polymer solution 1
= 0% by weight. After applying the thus obtained polarizing plate adhesive solution to a polyester release film,
Let dry. At this time, the coating thickness after drying was adjusted to be 25 μm.

Next, the adhesive applied on the release film was transferred onto a 200 μm polarizing film,
The polarizing plate of the present invention was obtained by aging for 7 days at 65 ° C. and a humidity of 65%.

The polarizing plate provided with the pressure-sensitive adhesive layer was placed in a 60 mm × 10 mm so that the absorption axis was at 45 ° to the long side of the polarizing plate.
This polarizing plate was cut on one side of a glass plate,
At 0 ° C., pressure 5 kg / cm ² , the adhesive was held for 20 minutes.

The sample thus obtained was allowed to stand at 100 ° C. and 80 ° C. and 90% for 500 hours, and the state of foaming and peeling was evaluated by visual observation. Table 2 shows the results.

The samples prepared in the same manner were placed on both surfaces of a glass plate so that the absorption axes were perpendicular to each other, and were held at 50 ° C. under a pressure of 5 kg / cm ² for 20 minutes to be adhered.
The sample thus obtained was subjected to 500
Then, the state of occurrence of color unevenness was evaluated by visual observation, and the displacement distance of the bonding position on the long side of the polarizing plate was measured with a vernier caliper. Table 2 shows the results.

[0072]

Example 2 Polymer solution 2 and polymer solution 7 were mixed at a solid content ratio of 100 parts by weight / 25 parts by weight, and a polyisocyanate compound (trade name: Coronate L, Japan) was used as a polyfunctional compound. 1.0 part by weight of a solid component (manufactured by Polyurethanes Inc.) was added, and the mixture was stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is defined as polymer solution 7 / polymer solution 2
= 12.5% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

With respect to this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0075]

Example 3 Polymer solution 2 and polymer solution 9 were mixed at a solid content ratio of 100 parts by weight / 100 parts by weight.
The polyfunctional compound is a polyisocyanate compound (trade name: Coronate HL, Nippon Polyurethane Co., Ltd.)
0.04 parts by weight of a solid component was added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is as follows: polymer solution 9 / polymer solution 2
= 0% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

With respect to this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0078]

Example 4 Polymer solution 1 and polymer solution 9 were mixed at a solid content ratio of 100 parts by weight / 25 parts by weight, and the epoxy compound 0.02 used in Example 1 was used as a polyfunctional compound. By weight, the mixture was stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is defined as polymer solution 9 / polymer solution 1
= 0% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

For this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0081]

COMPARATIVE EXAMPLE 1 Polymer solution 1 and polymer solution 5 were mixed at a solid content ratio of 100 parts by weight / 10 parts by weight, and the epoxy compound having a solid content of 0.1% was used as a polyfunctional compound in Example 1. 02 parts by weight were added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is as follows: polymer solution 5 / polymer solution 1
= 0% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

For this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0084]

COMPARATIVE EXAMPLE 2 Polymer solution 2 and polymer solution 9 were mixed at a solid content ratio of 100 parts by weight / 250 parts by weight, and the polyisocyanate compound used in Example 3 as a polyfunctional compound having a solid content of 0% was added. .04 parts by weight were added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is as follows: polymer solution 9 / polymer solution 2
= 0% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

For this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0087]

Comparative Example 3 The polymer solution 1 and the polymer solution 6 were mixed at a solid content ratio of 100 parts by weight / 150 parts by weight. 02 parts by weight were added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is defined as polymer solution 6 / polymer solution 1
= 0% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

For this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0090]

COMPARATIVE EXAMPLE 4 Polymer solution 4 and polymer solution 5 were mixed at a solid content ratio of 100 parts by weight / 150 parts by weight, and the epoxy-based compound having a solid content of 0.1% used as a polyfunctional compound in Example 1 was added. 04 parts by weight were added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is defined as polymer solution 5 / polymer solution 4
= 0% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

With respect to this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0093]

Comparative Example 5 Polymer solution 2 and polymer solution 7 were mixed at a solid content ratio of 100 parts by weight / 40 parts by weight, and the polyisocyanate-based compound solid content 1 used in Example 2 as a polyfunctional compound was added thereto. Was added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is defined as polymer solution 7 / polymer solution 2
= 20% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

With respect to this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0096]

Comparative Example 6 The polymer solution 2 and the polymer solution 8 were mixed at a solid content ratio of 100 parts by weight / 20 parts by weight, and the polyfunctional isocyanate compound used in Example 2 was used as a polyfunctional compound. Was added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is defined as polymer solution 8 / polymer solution 2
= 100% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

With respect to this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0099]

COMPARATIVE EXAMPLE 7 Polymer solution 2 and polymer solution 3 were mixed at a solid content ratio of 100 parts by weight / 100 parts by weight, and the polyisocyanate compound used in Example 3 was used as a polyfunctional compound. .04 parts by weight were added and stirred well to obtain a pressure-sensitive adhesive solution for a polarizing plate.

The ratio of the amount of the functional group having reactivity to the polyfunctional compound is defined as polymer solution 3 / polymer solution 2
= 0% by weight. Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1.

For this polarizing plate, the occurrence of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

[0102]

Comparative Example 8 0.02 parts by weight of a solid content of an epoxy compound used in Example 1 as a polyfunctional compound was added to 100 parts by weight of a solid content of a polymer solution 1, and the mixture was stirred well to give a pressure-sensitive adhesive solution for a polarizing plate. I got

Using the pressure-sensitive adhesive for a polarizing plate thus obtained, a polarizing plate provided with a pressure-sensitive adhesive layer was prepared in the same manner as in Example 1. About this polarizing plate, the generation state of foaming and peeling was observed in the same manner as in Example 1. Further, the state of occurrence of color unevenness was observed, and the shift distance on the long side of the polarizing plate was measured. Table 2 shows the results.

Table 3 shows the mixing ratios of the polymer solutions in the above Examples and Comparative Examples.

[0105]

[Table 1]

[0106]

[Table 2]

[0107]

[Table 3]

Claims (4)

[Claims] 1. A polyfunctional compound comprising a repeating unit derived from (A) a (meth) acrylate ester as a main repeating unit.
(C) a repeating unit derived from a functional group-containing monomer reactive to (C) is copolymerized in an amount of 0.5 to 20% by weight and has a weight average molecular weight of 1,000,000 or more.
(B) a functional group-containing monomer reactive with the polyfunctional compound (C) based on 100 parts by weight of the (meth) acrylic copolymer and 100 parts by weight of the high molecular weight (meth) acrylic copolymer Low molecular weight having a weight average molecular weight of 30,000 or less, wherein the derived repeating unit is polymerized in an amount of 0 to 10% by weight.
(C) the high molecular weight (meth) acrylic copolymer (A) and / or the low molecular weight (meth) acrylic (co) polymer
A polyfunctional compound having at least two functional groups capable of forming a crosslinked structure by bonding to (B) in the molecule 0.005 to 5;
Parts by weight of the polyfunctional compound (C) copolymerized with the high molecular weight (meth) acrylic copolymer (A) and the low molecular weight (meth) acrylic (co) polymer (B). The repeating unit derived from the reactive functional group-containing monomer is a high molecular weight (meth) acrylic copolymer (A) and a low molecular weight (meth) acrylic copolymer having a functional group distribution represented by the following formula: (Co) polymer
(B) an adhesive for a polarizing plate, characterized in that: functional group partitioning ratio = [reactive with the polyfunctional compound (C) in the low molecular weight (meth) acrylic copolymer. Monomer-equivalent weight of repeating unit derived from functional group-containing monomer / repeat derived from functional group-containing monomer having reactivity with polyfunctional compound (C) in high molecular weight (meth) acrylic copolymer Weight in units of monomer] × 100 = 0 to 15% by weight. 2. The high molecular weight (meth) acrylic copolymer
The weight average molecular weight of (A) is in the range of 1,000,000 to 2,000,000, and the low molecular weight (meth) acrylic (co) polymer
The pressure-sensitive adhesive for a polarizing plate according to claim 1, wherein the weight average molecular weight of (B) is in the range of 1,000 to 20,000. 3. A polyfunctional compound comprising a repeating unit derived from a (meth) acrylate ester as a main repeating unit.
(C) a repeating unit derived from a functional group-containing monomer reactive to (C) is copolymerized in an amount of 0.5 to 20% by weight and has a weight average molecular weight of 1,000,000 or more.
(B) a functional group-containing monomer reactive with the polyfunctional compound (C) based on 100 parts by weight of the (meth) acrylic copolymer and 100 parts by weight of the high molecular weight (meth) acrylic copolymer Low molecular weight having a weight average molecular weight of 30,000 or less, wherein the derived repeating unit is polymerized in an amount of 0 to 10% by weight.
(C) the high molecular weight (meth) acrylic copolymer (A) and / or the low molecular weight (meth) acrylic (co) polymer
A polyfunctional compound having at least two functional groups capable of forming a crosslinked structure by bonding to (B) in the molecule 0.005 to 5;
Parts by weight of the polyfunctional compound (C) copolymerized with the high molecular weight (meth) acrylic copolymer (A) and the low molecular weight (meth) acrylic (co) polymer (B). The repeating unit derived from the reactive functional group-containing monomer is a high molecular weight (meth) acrylic copolymer (A) and a low molecular weight (meth) acrylic copolymer having a functional group distribution represented by the following formula: (Co) polymer
(B) a polarizing plate, wherein a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive characterized by being formed on at least one surface of the polarizing plate; functional group distribution ratio = [low molecular weight ( Weight of repeating unit derived from a functional group-containing monomer having reactivity with the polyfunctional compound (C) in the (meth) acrylic copolymer in terms of monomer / high molecular weight (meth) acrylic copolymer Monomer equivalent weight of a repeating unit derived from a functional group-containing monomer having reactivity with the polyfunctional compound (C)] × 100 = 0 to 15% by weight. 4. The high molecular weight (meth) acrylic copolymer has a weight average molecular weight (A) in the range of 1,000,000 to 2,000,000, and the low molecular weight (meth) acrylic (co) polymer
The polarizing plate according to claim 3, wherein the weight average molecular weight of (B) is in the range of 1,000 to 20,000.