KR20180098522A - A composition for a pressure-sensitive adhesive, a pressure-sensitive adhesive layer and a pressure- - Google Patents

Abstract

An object of the present invention is to provide a composition for a pressure-sensitive adhesive which is capable of forming a pressure-sensitive adhesive layer which exhibits good adhesion even when adhered to a polyolefin low-polarity material such as polypropylene and has excellent durability under a high temperature load environment .
(Meth) acrylic acid ester polymer molecule (a) having a structure having a tri-thiocarbonate structure and having a hydroxyl group at both terminals of the molecule and derived from a carboxyl group-containing monomer, (Meth) acrylic polymer (A) having a weight average molecular weight (Mw) of 300,000 to 600,000 and a molecular weight distribution (Mw / Mn) of not more than 4.0 as measured by a chromatographic method and isoparaffin having two or more isocyanate groups in one molecule (C) a cyanate compound (B) in an amount of 0.1 to 5 parts by mass based on 100 parts by mass of the (meth) acrylic polymer (A) and a softening point of at least 95 ° C.

Description

A composition for a pressure-sensitive adhesive, a pressure-sensitive adhesive layer and a pressure-

The present invention relates to a composition for a pressure-sensitive adhesive, a pressure-sensitive adhesive layer and a pressure-sensitive adhesive sheet.

In recent years, in the field of pressure-sensitive adhesives, there is a demand for a highly reliable pressure-sensitive adhesive which has a good adhesive force and has excellent durability that does not peel off even under more severe conditions.

Generally, when a pressure-sensitive adhesive containing a main component of an acrylic polymer is bonded to a polyolefin low-polarity material such as polyethylene or polypropylene, it is necessary to add a suitable tackifier in the pressure-sensitive adhesive in order to exhibit good adhesion.

For example, Patent Document 1 discloses an adhesive tape having a pressure-sensitive adhesive layer containing a polymer component containing a specific acrylic polymer and a rosin-based pressure-sensitive adhesive resin or a terpene-based pressure-sensitive adhesive resin.

However, there is a case where a pressure-sensitive adhesive layer having sufficient durability under a load environment is not obtained in the case of adhering to a polyolefin-based low-polarity material only by adding an adhesion-imparting agent to a conventional general acrylic polymer.

The pressure-sensitive adhesive is also required to have durability under high temperature conditions.

Patent Document 2 discloses a composition for a pressure-sensitive adhesive containing a specific (meth) acrylic acid ester polymer and a polyfunctional isocyanate compound. However, the weight average molecular weight of the polymer disclosed in the example of Patent Document 2 is 70,000 to 250,000, and the durability under high temperature conditions is not sufficient.

Japanese Patent Application Laid-Open No. 2015-110724 International Publication No. 2014/192492

It is an object of the present invention to provide a composition for a pressure-sensitive adhesive which is capable of forming a pressure-sensitive adhesive layer that exhibits good adhesion even when adhered to a polyolefin-based low-polarity material such as polypropylene and has excellent durability under a high-temperature load environment.

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above problems. As a result, it has been found that the above problems can be solved by a composition for a pressure-sensitive adhesive containing a specific (meth) acrylic polymer, a specific amount of a polyfunctional isocyanate compound and a specific tackifier, .

The present invention is, for example, the following [1] to [6].

(1) A polymer comprising a (meth) acrylic acid ester polymer molecule (a) having a structure represented by the formula (a1) and having a hydroxyl group at both terminals of the molecule and having a structural unit derived from a carboxyl group- (Meth) acrylic polymer (A) having a weight average molecular weight (Mw) of 300,000 to 600,000 and a molecular weight distribution (Mw / Mn) of not more than 4.0 as measured by a permeation chromatography method and an isocyanate group (B) in an amount of 0.1 to 5 parts by mass based on 100 parts by mass of the (meth) acrylic polymer (A), and a tackifier (C) having a softening point of 95 캜 or more.

[2] The composition for a pressure-sensitive adhesive according to [1], wherein the (meth) acrylic polymer (A) is a reversibly adduct cleavage chain transfer (RAFT) polymer of a polymerizable double bond-containing monomer containing a carboxyl group-containing monomer.

[3] The polymer according to [1] or [2], wherein the (meth) acrylic polymer (A) is a polymer of a polymerizable double bond-containing monomer in which the amount of the monomer having at least one kind selected from a hydroxyl group and an amino group is 0.3% A composition for a pressure-sensitive adhesive.

[4] The pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the (meth) acrylic acid ester polymer molecule (a) is a polymer represented by the formula (A1-1).

[In the formula (A1-1), R ¹ is independently a divalent organic group, and (A) is a divalent group derived from a polymer of a polymerizable double bond-containing monomer each independently containing a carboxyl group-containing monomer .]

[5] A pressure-sensitive adhesive layer obtained from the composition for a pressure-sensitive adhesive according to any one of [1] to [4].

[6] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer according to [5].

According to the present invention, it is possible to provide a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer that exhibits a good adhesive force even when adhered to a polyolefin-based low-polarity material such as polypropylene and has excellent durability under a high temperature load environment.

(Mode for carrying out the invention)

Hereinafter, the composition for a pressure-sensitive adhesive of the present invention, the pressure-sensitive adhesive layer and the pressure-sensitive adhesive sheet will be described.

In the present specification, the term " polymer " is used to mean a homopolymer and a copolymer, and the term " polymerization " is used to mean homopolymerization and copolymerization.

Also, acrylic and methacrylic are collectively referred to as " (meth) acrylic ".

[Composition for pressure-sensitive adhesive]

The composition for a pressure-sensitive adhesive of the present invention comprises a specific (meth) acrylic polymer (A) containing a specific (meth) acrylic acid ester polymer molecule (a) (hereinafter also referred to as " (B) (hereinafter also referred to as " multifunctional isocyanate compound (B) ") having an anate group of 2 or more and a specific tackifier (C).

<( Meta )acryl Polymer (A)

(Meth) acrylic polymer (A) comprises a polymer molecule (a).

<( Meta ) Acrylic acid ester polymer molecule (a) &gt;

The polymer molecule (a) has a structure represented by the formula (a1), has a hydroxyl group at both ends of the molecule, and has a structural unit derived from a carboxyl group-containing monomer.

The polymer molecule (a) has a structure represented by the formula (a1) (hereinafter also referred to as a &quot; tricyanocarbonate structure &quot;).

In the polymer molecule (a), the hydroxyl groups at both ends of the molecule are crosslinked with the polyfunctional isocyanate compound (B) to form a crosslinked product (network polymer). Since the crosslinked product is excellent in stress relaxation property, the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition of the present invention can maintain a high static-load peeling property even at a high temperature and is considered to have excellent durability.

Further, the polymer molecule (a) has a structural unit derived from a carboxyl group-containing monomer. In order that the polymer molecule (a) has a structural unit derived from a carboxyl group-containing monomer, for example, a monomer containing a carboxyl group is used as the polymerizable double bond-containing monomer. By having a structural unit derived from a carboxyl group-containing monomer, the reaction between the hydroxyl group of the polymer molecule (a) and the isocyanate group of the polyfunctional isocyanate compound (B) can be promoted, It is possible to form a pressure-sensitive adhesive layer having excellent durability. Further, since the polymer molecule (a) has a structural unit derived from a carboxyl group-containing monomer, the pressure-sensitive adhesive layer formed from the composition for a pressure-sensitive adhesive containing the polymer molecule (a) has a durability great.

The weight average molecular weight (Mw) of the polymer molecule (a) measured by gel permeation chromatography (GPC) is preferably 300,000 to 600,000, more preferably 320,000 to 550,000, and still more preferably 330,000 to 500,000 .

The molecular weight distribution (Mw / Mn) of the polymer molecule (a) is preferably 4.0 or less, more preferably 1.5 to 3.8, and still more preferably 1.8 to 3.5.

Mw and Mw / Mn can be measured, for example, by the methods described in Examples.

The polymer molecule (a) is obtained by reacting a polymerizable double bond-containing monomer such as (meth) acrylic acid ester with a compound represented by the formula (A1) (hereinafter also referred to as a compound (A1) It is preferable that the polymer is obtained by polymerizing by a method.

In formula (A1), R ¹ is each independently a divalent organic group.

The compound (A1) has a triisocyanate structure in the molecule and a hydroxyl group at both ends of the molecule. The compound (A1) can be synthesized, for example, according to the method described in Japanese Patent Application Laid-Open No. 2007-230947. By using the compound (A1) having the above structure, a telilgic structure can be formed without containing harmful organic metal.

By RAFT polymerization, it is possible to obtain a polymer having a high symmetrical property, in which the repeating structural units originating in the polymerizable double bond-containing monomer are bonded almost equally to both sides of the triacyanocarbonate structure in the molecule and a hydroxyl group is bonded to both ends of the molecule Can be obtained.

As the compound (A1), for example, a compound represented by the formula (A2) (hereinafter also referred to as a "compound (A2)") and a compound represented by the formula (A3) ).

The compound (A2) has a triacyanocarbonate structure in the molecule and has hydroxyl groups at both ends of the molecule. As the compound (A2), for example, RAFT-NT manufactured by Nippon Terpene Chemical Co., Ltd. may be mentioned.

In the formula (A2), X is independently -COO-, -CONR ³ - or a direct bond, R ³ is each independently an alkyl group, the number of carbon atoms of the alkyl group is preferably 1 to 4, more preferably 1 ~ 3; R ² each independently represents an alkylene group, and the number of carbon atoms of the alkylene group is preferably 1 to 12, more preferably 1 to 6; Ar is independently a group formed by substituting at least one aromatic ring hydrogen contained in a phenylene group, a naphthylene group or a phenylene group or a naphthylene group with a substituent. Examples of the substituent include an alkyl group and an alkoxy group. In the case of X, carbonyl groups in -COO- and -CONR ³ - are bonded to Ar. X 2 is preferably the same group, and two R ² are preferably the same group, and preferably, the two R ³ are preferably the same group, and Ar 2 are the same group.

The compound (A3) has a triisocyanate structure in its molecule and has two hydroxyl groups at both ends of the molecule. As the compound (A3), for example, RAFT-DiOH manufactured by Nippon Terpene Chemical Co., Ltd. may be mentioned.

In formula (A3), X and Ar are the same as those in formula (A2); R ⁴ are each independently an alkylene group, and R ⁵ is each independently a direct bond or an alkylene group, and the number of carbon atoms of these alkylene groups is preferably 1 to 12, more preferably 1 to 6. It is preferable that two Xs are the same group, two R ⁴ groups are preferably the same group, two R ⁵ groups are preferably the same group, and two Ar groups are preferably the same groups.

Specific examples of the compound (A1) are shown below.

In the RAFT polymerization, the polymerizable double bond-containing monomer is polymerized in the presence of the compound (A1). The amount of the compound (A1) to be used is generally 0.05 to 20 parts by mass, preferably 0.05 to 10 parts by mass, based on 100 parts by mass of the total amount of the polymerizable double bond-containing monomers. When the amount of the compound (A1) to be used is lower than the lower limit of the above range, the reaction can be easily controlled. If the upper limit of the above range is exceeded, the weight average molecular weight of the obtained polymer is easily adjusted to the above range.

For example, the polymerizable double bond-containing monomer may be inserted between the sulfur atom in the compound (A1) and the methylene group adjacent to the sulfur atom to form a polymer represented by the formula (A1-1) (Hereinafter also referred to as "polymer (A2-1)" or "polymer (A3-1)"), and specific examples thereof are polymers represented by formula (A2-1) .

In formula (A1-1), R ¹ is synonymous with the same symbol in formula (A1), and (A) independently represents a divalent group derived from a polymer of a polymerizable double bond-containing monomer containing a carboxyl group- (The polymer chain of the polymerizable double bond-containing monomer).

In formula (A2-1), X, R ² and Ar are the same as those in formula (A2), and (A) is independently derived from a polymer of a polymerizable double bond-containing monomer containing a carboxyl group- (A polymer chain of a polymerizable double bond-containing monomer).

In formula (A3-1), X, R ⁴ , R ⁵ and Ar are the same as those in formula (A3), and (A) independently represents a polymerizable double bond-containing monomer containing a carboxyl group- And a divalent group derived from the polymer (polymer chain of the polymerizable double bond-containing monomer).

The A (divalent group derived from the polymer) in the formulas (A1-1) to (A3-1) may be any of a homopolymer structure and a copolymer structure of the polymerizable double bond-containing monomer, and the copolymer structure A random copolymer structure of a polymerizable double bond-containing monomer, and a block copolymer structure.

In the above A (divalent group derived from a polymer) in the formulas (A1-1) to (A3-1), the number of repeating structural units derived from the polymerizable double bond-containing monomer is such that the Mw of the polymer molecule (a) .

The block copolymer structure can be obtained by, for example, adding a polymerizable double bond-containing monomer to the compound (A1) to perform a first RAFT polymerization, adding an additional polymerizable double bond-containing monomer to the obtained polymer, Followed by polymerization. Although an example of a two-component system block structure is described here, it may be a three-component system block structure or the like, and is not particularly limited. Examples of the polymer (A1-2) include a polymer represented by the formula (A2-2) or the formula (A3-2) (hereinafter referred to as "polymer (A1-2)", "polymer (A2-2) (A3-2) &quot;).

In formula (A1-2), R ¹ is synonymous with the same symbol in formula (A1), and (A ¹ ) and (A ² ) each independently represent a polymer of a polymerizable double bond-containing monomer containing a carboxyl group- (A polymer chain of a polymerizable double bond-containing monomer).

In formula (A2-2), X, R ² and Ar are the same as those in formula (A2), and (A ¹ ) and (A ² ) each independently represent a polymerizable double bond (Polymer chain of the polymerizable double bond-containing monomer) derived from the polymer of the polymerizable double bond-containing monomer.

In formula (A3-2), X, R ⁴ , R ⁵ and Ar are the same as those in formula (A3), and each of A ¹ and A ² independently represents a polymerization (A polymer chain of a polymerizable double bond-containing monomer) derived from a polymer of a monomer having a double bond.

When a polymer having a block copolymer structure such as polymers (A1-2) to (A3-2) is used as the polymer chain of the polymerizable double bond-containing monomer as the polymer molecule (a), the resulting pressure- Hydrophobicity - hydrophilicity, flexibility - rigidity according to purpose.

The RAFT polymer having the above structure has a soft segment derived from the polymer chain of the polymerizable double bond-containing monomer. Therefore, the isocyanate group of the polyfunctional isocyanate compound (B) is likely to approach the terminal hydroxyl group of the RAFT polymer, so that the formation of the urethane bond is thought to proceed effectively.

The polymer molecules (a) may be used alone or in combination of two or more.

The (meth) acrylic polymer (A) may further comprise a polymer other than the polymer molecule (a) in addition to the polymer molecule (a). Examples of the polymer other than the polymer molecule (a) include, for example, by-products of RAFT polymerization when the polymer molecule (a) is produced by RAFT polymerization.

The content of the polymer molecule (a) in the (meth) acrylic polymer (A) is not particularly defined, and the polymer molecule (a) may be contained in the (meth) acrylic polymer (A).

The (meth) acrylic polymer (A) is obtained, for example, by RAFT polymerization.

The (meth) acrylic polymer (A) is preferably a RAFT polymer of a polymerizable double bond-containing monomer containing a carboxyl group-containing monomer.

The polymerizable double bond-containing monomer used for forming the (meth) acrylic polymer (A) is preferably the same as the polymerizable double bond-containing monomer used for forming the polymer molecule (a). That is, it is preferable that the polymer molecule (a) and the polymer other than the polymer molecule (a) contained in the (meth) acrylic polymer (A) are polymers formed from the same polymerizable double bond-containing monomer.

The Mw of the (meth) acrylic polymer (A) measured by GPC is 300,000 to 600,000, preferably 320,000 to 550,000, and more preferably 330,000 to 500,000. By using the acrylic polymer (A) having the Mw within the above range, a pressure-sensitive adhesive layer having excellent durability under a high-temperature load environment can be obtained.

The Mw / Mn of the (meth) acrylic polymer (A) is 4.0 or less, preferably 1.5 to 3.8, and more preferably 1.8 to 3.5. Since the (meth) acrylic polymer (A) having the Mw / Mn in the above range has a uniform molecular weight and a low low molecular weight, the resultant crosslinked product has excellent heat resistance, and the low molecular weight at the time of peeling the pressure- It is possible to suppress the contamination of the adherend by the polymer.

Mw and Mw / Mn can be measured, for example, by the methods described in Examples.

The content of the (meth) acrylic polymer (A) in the pressure-sensitive adhesive composition is usually 10 to 95 mass% in 100 mass% of the composition for a pressure-sensitive adhesive.

" Polymerizable  Double bond containing monomer &quot;

(Meth) acrylic polymer (A) containing the polymer molecule (a) can be obtained by, for example, RAFT polymerization of the polymerizable double bond-containing monomer. As the polymerizable double bond-containing monomer, at least a (meth) acrylic acid ester and a carboxyl group-containing monomer are used. From the (meth) acrylic acid ester, the functional group-containing (meth) acrylate such as carboxyl group-containing (meth) acrylate, hydroxyl group-containing (meth) acrylate and amino group-containing (meth) acrylate is excluded.

In addition, as the polymerizable double bond-containing monomer, at least one member selected from functional group-containing monomers other than the carboxyl group and copolymerizable monomers other than the functional group-containing monomer may be used.

<( Meta ) Acrylic acid ester>

Since the polymer molecule (a) has a structural unit derived from a (meth) acrylic acid ester, a (meth) acrylic acid ester is used as the polymerizable double bond-containing monomer.

Examples of the (meth) acrylic esters include alkyl (meth) acrylates, alkoxyalkyl (meth) acrylates, alkoxypolyalkyleneglycolmono (meth) acrylates, alicyclic groups or aromatic ring containing Rate.

The alkyl group in the alkyl (meth) acrylate preferably has 1 to 20 carbon atoms. Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, (Meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobutyl (Meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undeca (Meth) acrylate, iso-stearyl (meth) acrylate, and didecka (meth) acrylate.

Examples of the alkoxyalkyl (meth) acrylate include methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl Methoxybutyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate and 4-ethoxybutyl (meth) acrylate.

Examples of the alkoxypolyalkylene glycol mono (meth) acrylate include methoxy diethylene glycol mono (meth) acrylate, methoxy dipropylene glycol mono (meth) acrylate, ethoxy triethylene (Meth) acrylate, methoxytriethylene glycol mono (meth) acrylate, methoxytriethylene glycol mono (meth) acrylate, and the like.

Examples of the alicyclic group- or aromatic ring-containing (meth) acrylate include cyclohexyl (meth) acrylate, benzyl (meth) acrylate and phenyl (meth) acrylate.

(Meth) acrylic acid ester may be used alone or in combination of two or more.

The amount of the (meth) acrylic acid ester to be used is generally 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more, based on 100% by mass of the total polymerizable double bond-containing monomer.

In the RAFT polymerization process, in the case of forming a block-copolymer structure, e.g., in the polymer (A1-2) ~ (A3-2), containing polymerizable double bonds to form the A ¹ and A ² each It is preferred that the monomers each comprise different types of monomers selected from (meth) acrylic acid esters.

< Carboxyl group  Containing monomers>

Since the polymer molecule (a) has a structural unit derived from a carboxyl group-containing monomer, a carboxyl group-containing monomer is used as the polymerizable double bond-containing monomer.

Examples of the carboxyl group-containing monomers include (meth) acrylic acid? -Carboxyethyl, (meth) acrylic acid 5-carboxypentyl, succinic acid mono (meth) acryloyloxyethyl ester,? -Carboxypolycaprolactone mono (Meth) acrylate containing carboxyl group such as acrylate; Acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid, and maleic acid.

The carboxyl group-containing monomers may be used singly or in combination of two or more.

The amount of the carboxyl group-containing monomer to be used is generally 0.5 to 15 mass%, preferably 1 to 12 mass%, and more preferably 3 to 10 mass%, based on 100 mass% of the polymerizable double bond-containing monomer.

< Carboxyl group  Functional group-containing monomers>

Examples of the functional group-containing monomer other than the carboxyl group include an acid group-containing monomer other than the carboxyl group, a hydroxyl group-containing monomer, an amino group-containing monomer, an amide group-containing monomer, a nitrogen- . Examples of the acid group other than the carboxyl group include an acid anhydride group, a phosphoric acid group and a sulfuric acid group.

Examples of the acid group-containing monomer other than the carboxyl group include monomers containing acid anhydride groups such as phthalic anhydride and maleic anhydride; Monomers containing phosphoric acid groups such as (meth) acrylic monomers having a phosphoric acid group in the side chain; And (meth) acrylic monomers having a sulfate group in the side chain.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl Acrylate, and (meth) acrylate having a hydroxyl group such as 8-hydroxyoctyl (meth) acrylate.

Examples of the amino group-containing monomer include amino group-containing (meth) acrylates such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.

Examples of the amide group-containing monomer include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N- Amides. Examples of the nitrogen-containing heterocyclic ring-containing monomer include vinyl pyrrolidone, acryloylmorpholine, and vinylcarrolactam. Examples of the cyano group-containing monomer include cyano (meth) acrylate and (meth) acrylonitrile.

The functional group-containing monomers may be used alone or in combination of two or more.

In the synthesis of the polymer molecule (a), a functional group-containing monomer other than a carboxyl group may be used, but in the case of a copolymer of a monomer containing a functional group such as a hydroxyl group or an amino group, which has high reactivity with an isocyanate group, Nate crosslinking causes cross-linking at sites other than both ends of the molecule, and the free end is increased by a certain amount, so that the durability of the resultant pressure-sensitive adhesive layer may be lowered. Therefore, from the viewpoint of improvement in durability, the amount of the monomer having at least one kind selected from a hydroxyl group and an amino group is preferably 0.3 mass% or less, more preferably 0.1 mass% or less based on 100 mass% of the total polymerizable double bond- % Or less.

It is preferable that the polymer molecule (a) does not have a structural unit derived from a monomer containing a functional group having reactivity with an isocyanate group.

&Lt; Copolymerizable monomers &

Examples of the copolymerizable monomer include alkylstyrene such as styrene, methylstyrene, dimethylstyrene, trimethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene and octylstyrene , Styrene-based monomers such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodinated styrene, nitrostyrene, acetylstyrene and methoxystyrene, vinyl acetate have.

The copolymerizable monomers may be used singly or in combination of two or more.

" Polymerization initiator "

The RAFT polymerization is preferably carried out in the presence of a polymerization initiator. Examples of the polymerization initiator include conventional organic polymerization initiators. Specific examples thereof include azo compounds such as peroxides such as benzoyl peroxide and lauroyl peroxide, and 2,2'-azobisisobutyronitrile. . Of these, azo compounds are preferred.

Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2 ' Azobis (2-cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile) (Cyclohexane-1-carbonitrile), 2- (carbamoylazo) isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronite Azo compounds such as 2,2'-azobis (N, N'-dimethyleneisobutylamidine), 2,2'-azobis [2,2'-azobis (2-hydroxyethyl) -propionamide], 2,2'-azobis (isobutylamide) dihydrate, 4,4'-azobis , 2'-azobis (2 -cyanopropanol), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis [ N- (2-hydroxyethyl) propionamide].

The polymerization initiator may be used alone or in combination of two or more.

The amount of the polymerization initiator to be used is generally 0.001 to 2 parts by mass, preferably 0.002 to 1 part by mass based on 100 parts by mass of the polymerizable double bond-containing monomer. By using the polymerization initiator within the above range, the Mw of the (meth) acrylic polymer (A) can be adjusted within an appropriate range.

&Quot; Polymerization conditions &

The reaction temperature in the RAFT polymerization method is usually 60 to 120 占 폚, preferably 70 to 110 占 폚. Usually, the reaction is carried out in an inert gas atmosphere such as nitrogen gas. This reaction can be carried out under any conditions of normal pressure, And is usually performed at normal pressure. The reaction time is usually 1 to 20 hours, preferably 2 to 14 hours. Regarding the polymerization conditions, reference can be made, for example, to Japanese Patent Application Laid-Open Nos. 2007-230947 and 2011-52057.

The RAFT polymerization is usually carried out without using a reaction solvent, but a reaction solvent may be used if necessary. Examples of the reaction solvent include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane and n-octane; Alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane and cyclooctane; Ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenyl ethyl ether and diphenyl ether; Halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane and chlorobenzene; Esters such as ethyl acetate, propyl acetate, butyl acetate and methyl propionate; Ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone; Amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone; Nitrites such as acetonitrile and benzonitrile; Dimethyl sulfoxide, sulfoxides such as sulfolane, and the like. These solvents may be used alone or in combination of two or more.

<Multifunction Isocyanate  The compound (B)

The polyfunctional isocyanate compound (B) is an isocyanate compound having two or more isocyanate groups in one molecule. The number of isocyanate groups in one molecule of the polyfunctional isocyanate compound (B) is preferably 2 to 8, more preferably 3 to 5. When the number of isocyanate groups is in the above range, the crosslinking reaction efficiency between the polymer molecule (a) and the isocyanate compound is preferable from the viewpoint of availability and availability.

Examples of the diisocyanate compound having an isocyanate group number of 2 in one molecule include an aliphatic diisocyanate, an alicyclic diisocyanate, and an aromatic diisocyanate. Examples of the aliphatic diisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate Aliphatic diisocyanates having 4 to 30 carbon atoms such as cyanate, 3-methyl-1,5-pentane diisocyanate and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate Cyanate. Examples of the alicyclic diisocyanate include isophoronediisocyanate, cyclopentyldiisocyanate, cyclohexyldiisocyanate, hydrogenated xylene diisocyanate, hydrogenated tolylene diisocyanate, Alicyclic diisocyanates having 7 to 30 carbon atoms such as hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethyl xylene diisocyanate, and the like. Examples of the aromatic diisocyanate include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, naphthylene diisocyanate, diphenyl ether isocyanate Aromatic diisocyanates having 8 to 30 carbon atoms such as diphenylmethane diisocyanate, diphenylmethane diisocyanate and diphenylpropane diisocyanate.

Examples of the isocyanate compound having three or more isocyanate groups in one molecule include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates. Specifically, 2,4,6-triisocyanatotoluene, 1,3,5-triisocyanate benzene, and 4,4 ', 4 "-triphenylmethane triisocyanate are reacted with .

As the isocyanate compound, for example, there can be used a mixture of two or more isocyanate compounds having an isocyanate group number of 2 or more, such as a multimer (for example, a dimer or trimer, burette, isocyanurate (For example, an addition reaction product of a polyhydric alcohol and two or more molecules of a diisocyanate compound), and a polymer. Examples of the polyhydric alcohol in the derivative include low molecular weight polyhydric alcohols such as trimethylolpropane, glycerin and pentaerythritol; and trihydric or higher alcohols; Examples of the high molecular weight polyhydric alcohol include polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol and polyisoprene polyol.

Examples of such isocyanate compounds include dimers of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, or tolylene diisocyanate Or a reaction product of trimethylolpropane and tolylene diisocyanate or xylene diisocyanate (for example, tolylene diisocyanate or xylene Diisocyanate), the reaction product of trimethylolpropane and hexamethylene diisocyanate (e.g., a three-molecule adduct of hexamethylene diisocyanate), a polyether Polyisocyanate, polyester polyisocyanate, and the like.

The multifunctional isocyanate compound (B) may be used alone or in combination of two or more.

The content of the polyfunctional isocyanate compound (B) in the pressure-sensitive adhesive composition is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 4 parts by mass, and still more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the (meth) Is 1 to 3 parts by mass. When the content of the compound (B) is within the above range, the pressure-sensitive adhesive layer having excellent durability can be obtained without deteriorating the cohesiveness of the resulting composition and having excellent balance of adhesive properties of the resulting composition. Particularly, when the compound (B) is used in an amount above the lower limit value, the reaction rate between the terminal hydroxyl group and the isocyanate group is improved, and the curing is sufficiently performed, so that the adhesive property is preferably exhibited.

< Tackifier (C)

Since the composition for a pressure-sensitive adhesive of the present invention contains the tackifier (C), it is possible to form a pressure-sensitive adhesive layer that exhibits good adhesion even when adhered to a polyolefin-based low-polarity material such as polypropylene.

The softening point of the tackifier (C) is 95 deg. C or higher, more preferably 95 to 150 deg. When the softening point of the tackifier (C) is within the above range, the pressure-sensitive adhesive layer has tackiness and excellent heat resistance, so that a pressure-sensitive adhesive layer having excellent durability in a high temperature environment can be obtained. The softening point can be measured at a heating rate of 5 ° C per minute from 23 ° C to 180 ° C by differential scanning calorimetry (DSC), for example.

As the tackifier (C), for example, rosin-based compounds such as rosin ester resins; And terpene compounds such as a terpene phenol resin. Examples of the rosin ester resin include a disproportionated rosin ester resin, a hydrogenated rosin ester resin, and a polymerized rosin ester resin.

Examples of the disproportionated rosin ester resin include Super Aster A-100 (a product of Arakawa Chemical Industries, Ltd., softening point 95 to 105 캜), Super Aster A-115 (Arakawa Kagaku Kogyo Co., softening point 108 to 120 캜) Super Aster A-125 (manufactured by Arakawa Chemical Industries, Ltd., softening point 120-130 占 폚). Examples of the hydrogenated rosin ester resin include Fine Crystal KE-604 (softening point 124 to 134 占 폚 manufactured by Arakawa Chemical Industries, Ltd.) and Fine Crystal KE-140 (softening point 130 to 150 占 폚 manufactured by Arakawa Chemical Industries, Ltd.) . Examples of the above-mentioned polymerized rosin ester resin include pendant A (available from Arakawa Chemical Industries, Ltd., softening point of 100 占 폚 or higher), Phencel C (manufactured by Arakawa Chemical Industries, Ltd., softening point 117 to 127 占 폚), PENCEL D- (Softening point: 130 to 140 캜), and PENCEL D-160 (manufactured by Arakawa Chemical Industries, Ltd., softening point: 150 to 165 캜).

Examples of the terpenephenol resin include YS Polystar G150 (Yasuhara Chemical Co., Ltd., softening point 145 to 155 占 폚), YS Polystar G125 (Yasuhara Chemical Co., Ltd., softening point 120 to 130 占 폚), YS Polystar T100 YS Polystar T 130 (manufactured by Yasuhara Chemical Co., Ltd., softening point 125 to 135 캜), YS Polystar T145 (manufactured by Yasuhara Chemical Co., Ltd., softening point 95 to 105 캜), YS Polystar T115 TAMANOL 80L (manufactured by Arakawa Chemical Industries, Ltd., softening point 145-160 占 폚), Tamanol 901 (manufactured by Arakawa Chemical Industries, Ltd., softening point 120-135 占 폚).

These tackifiers (C) may be used alone or in combination of two or more.

The content of the tackifier (C) in the pressure-sensitive adhesive composition is usually 5 to 50 parts by mass, preferably 8 to 40 parts by mass, more preferably 10 to 30 parts by mass, per 100 parts by mass of the (meth) acrylic polymer (A) 30 parts by mass. When the content of the tackifier (C) is in the above range, the pressure-sensitive adhesive layer has an appropriate tackiness and is excellent in adhesion to an olefinic low-polarity material.

<Additives>

The composition for a pressure-sensitive adhesive of the present invention may contain, in addition to the above components, an organic solvent, an antistatic agent, an ultraviolet absorber, an antioxidant, a tackifier resin other than the above (C), a plasticizer, , A stabilizer, a softening agent, and a wettability-adjusting agent.

As the organic solvent, the reaction solvent described in the column of &quot; polymerization conditions &quot; of the RAFT polymerization can be used. For example, a polymer solution containing a (meth) acrylic polymer (A) and a reaction solvent obtained by RAFT polymerization, a multifunctional isocyanate compound (B) and a tackifier (C) Can be prepared. In the composition for a pressure-sensitive adhesive of the present invention, the content of the organic solvent is usually 0 to 90 mass%, preferably 10 to 80 mass%.

[ The pressure- ]

The pressure-sensitive adhesive layer of the present invention can be obtained by crosslinking the above-mentioned pressure-sensitive adhesive composition, specifically by crosslinking the (meth) acrylic polymer (A) containing the (meth) acrylic acid ester polymer molecule (a) with the polyfunctional isocyanate compound ). &Lt; / RTI &gt; The pressure-sensitive adhesive layer thus obtained exhibits good adhesion even when adhered to a polyolefin-based low-polarity material such as polypropylene, and has excellent durability under a high-temperature load environment.

The thickness of the pressure-sensitive adhesive layer is usually 3 to 100 占 퐉, preferably 5 to 50 占 퐉.

The pressure-sensitive adhesive layer preferably has a gel fraction of from 20 to 90 mass%, more preferably from 30 to 80 mass%, further preferably from 40 to 70 mass%, from the viewpoints of suppression of deformation of the polarizing plate, improvement of cohesive force, Mass%.

The conditions for forming the pressure-sensitive adhesive layer are as follows. For example, the composition is coated on a support or a separator and dried at a temperature of usually 60 to 120 占 폚, preferably 70 to 110 占 폚, for 1 to 5 minutes, preferably 2 to 4 minutes to form a coating film.

The pressure-sensitive adhesive layer is preferably formed under the following conditions. The composition is coated on a support or a separator and the support or the separator is applied onto the coating film formed under the above conditions and then applied for 3 days or more, preferably 7 to 10 days, usually 5 to 60 占 폚, preferably 15 to 40 C, usually 30 to 70% RH, preferably 40 to 70% RH. When crosslinking is carried out under the above aging conditions, it is possible to efficiently form a crosslinked body (network polymer).

Examples of the support and the separator include a film made of a plastic such as a polyester such as a polyethylene terephthalate, a polyethylene, a polypropylene, an ethylene-vinyl acetate copolymer and the like; Non-woven; Paper separators.

[Adhesive sheet]

The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer comprising the composition for a pressure-sensitive adhesive described above. The pressure-sensitive adhesive sheet preferably has a substrate, and may have a separator on the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet includes, for example, a double-sided pressure-sensitive adhesive sheet having only the pressure-sensitive adhesive layer, a substrate, a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer formed on both surfaces of the substrate, a substrate, A pressure-sensitive adhesive sheet, and a pressure-sensitive adhesive sheet in which a separator is attached to a surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet that is not in contact with the substrate.

The thickness of the pressure-sensitive adhesive layer is usually 3 to 100 占 퐉, preferably 5 to 80 占 퐉. The thickness of the base material and the separator is not particularly limited, but is usually 10 to 100 占 퐉, preferably 25 to 50 占 퐉.

Examples of the substrate and the separator include a film made of a plastic such as a polyester such as a polyethylene terephthalate, a polyethylene, a polypropylene, an ethylene-vinyl acetate copolymer and the like; Non-woven; Paper separators.

INDUSTRIAL APPLICABILITY The pressure-sensitive adhesive sheet of the present invention exhibits good adhesion even when adhered to a polyolefin low-polarity material such as polyethylene or polypropylene, and has excellent durability under a high-temperature load environment.

Therefore, the pressure-sensitive adhesive sheet of the present invention can be widely used as an industrial pressure-sensitive adhesive sheet, but it can be used for a nonwoven double-sided tape or a double-sided tape for a urethane foam laminate,

( Example )

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. In the following description of examples and the like, &quot; part &quot; means &quot; part by mass &quot; unless otherwise stated.

Each measurement value in the examples was obtained by the following method.

[Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)] [

The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) of the (meth) acrylic polymer in terms of standard polystyrene standards were determined by gel permeation chromatography (GPC) under the following conditions.

Measurement apparatus: HLC-8120GPC (manufactured by Tosoh Corporation)

GPC Column Composition: The following five columns (all manufactured by Tosoh Corporation)

(1) TSK-GEL HXL-H (guard column)

(2) TSK-GEL G7000HXL

(3) TSK-GEL GMHXL

(4) TSK-GEL GMHXL

(5) TSK-GEL G2500HXL

Sample concentration: such that the 1.0mg / cm ^3, diluted with tetrahydrofuran

Mobile phase solvent: tetrahydrofuran

· Flow rate: 1.0 cm ³ / min

· Column temperature: 40 ° C

[heating Residue  Measure]

1 g of the (meth) acrylic polymer solution was precisely weighed in a blik chalche (mass: n1), and the total mass (n2) was precisely weighed and then heated at 105 DEG C for 3 hours. Thereafter, the blister material was allowed to stand in a desiccator at room temperature for one hour, and then precisely weighed again to measure the total mass (n3) after heating. Using the obtained mass measurement values (n1 to n3), the heating residue was calculated from the following formula.

Heating residue (mass%) = 100 占 [mass after heating (n3-n1) / mass before heating (n2-n1)]

<Acrylic Polymer >

[ Manufacturing example  A1]

To a flask equipped with a stirrer, a nitrogen gas introducing tube, a thermometer and a reflux condenser, 44 parts of n-butyl acrylate, 50 parts of 2-ethylhexyl acrylate, 6 parts of acrylic acid, (Hereinafter also referred to as &quot; RAFT No. 1 &quot;) (manufactured by Nippon Terpene Chemical Co., Ltd.) was charged into a flask and nitrogen gas was introduced into the flask The contents of the flask were heated to 80 占 폚.

RAFT After visually confirming the dissolution of the agent, 0.02 part of 2,2'-azobisisobutyronitrile (hereinafter also referred to as "AIBN") was added into the flask under stirring, and the temperature of the content in the flask was maintained at 80 ° C. And heating and cooling were performed for 1 hour. Subsequently, 100 parts of ethyl acetate was added dropwise over 1 hour while maintaining the temperature of the content in the flask at 80 DEG C, and then heating and cooling were performed for 10 hours so that the temperature of the contents in the flask could be maintained at 80 DEG C, 20 parts of ethyl were added.

Thus, a polymer solution containing the acrylic polymer (A1) was obtained. The molecular weight measured by GPC for the acrylic polymer (A1) contained in the obtained polymer solution was Mw: 380,000 and Mw / Mn: 2.4. The heating residue of the obtained polymer solution was 45 mass%.

[ Manufacturing example  A2 and B1 to B4]

A polymer solution containing acrylic polymer (A2) and (B1) to (B4) was obtained in the same manner as in Production Example 1, except that the component composition was changed as shown in Table 1 in Production Example A1. In Production Example B1, 60 parts of ethyl acetate was added dropwise over 1 hour while maintaining the temperature of the content in the flask at 80 占 폚, and 20 parts of the last portion of ethyl acetate was added.

The components shown in Table 1 are as follows.

BA: n-butyl acrylate

2-EHA: 2-ethylhexyl acrylate

2-HEA: 2-hydroxyethyl acrylate

AA: Acrylic acid

RAFT No. 1: Bis [4- {ethyl- (2-hydroxyethyl) aminocarbonyl} -benzyl] tri thiocarbonate

RAFT No. 2: S, S-dibenzyltriethiocarbonate

<Composition for pressure-sensitive adhesive and double-faced pressure-sensitive adhesive sheet>

[ Example  One]

A polymer solution containing the acrylic polymer (A1) obtained in Production Example A1 was mixed with D-125 (manufactured by Arakawa Chemical Industries, Ltd., softening point 120 to 130 占 폚) as a tackifier. To this mixture, L-45 (a tolylene diisocyanate cross-linking agent, manufactured by Soken Chemical & Engineering Co., Ltd., the number of isocyanate groups in one molecule was about 3) was mixed as an isocyanate compound to prepare a composition for a pressure- &Lt; / RTI &gt; Further, a mixing ratio of D-125 and L-45 to 100 parts of the acrylic polymer (A1) was 30 parts and 2.0 parts, respectively (solid content ratio).

The composition for a pressure-sensitive adhesive was coated on a paper separator (EKR-80D) which had been peeled off using a doctor blade after removing the foam to a thickness of 65 mu m after drying and dried in a dryer at 80 DEG C for 2 minutes to remove the solvent. The resultant pressure-sensitive adhesive coating film was applied to both sides of a nonwoven fabric base material having a thickness of 38 탆 and aged for 7 days under an environment of 23 캜 and 65% RH to form a paper separator / pressure-sensitive adhesive layer / nonwoven base / pressure- To obtain a double-sided pressure-sensitive adhesive sheet having a total tape thickness of 140 탆.

[ Example  2, 3, and Comparative Example  1-6]

A composition for a pressure-sensitive adhesive and a double-faced pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1 except that the composition components in Example 1 were changed as shown in Table 1.

The tackifier shown in Table 1 is as follows.

D-125: rosin-based tackifier (manufactured by Arakawa Chemical Industries, trade name: PENCEL D-125, softening point: 120 to 130 캜)

T145: terpene phenol resin (trade name: YS POLYSTAR T145, softening point: 140-150 DEG C, manufactured by Yasuhara Chemical Co., Ltd.)

A-75: rosin-based tackifier (manufactured by Arakawa Chemical Industries, trade name: Super Aster A-75, softening point: 70 to 80 캜)

<Evaluation>

[Gel fraction]

About 0.1 g of the pressure-sensitive adhesive layer obtained in Examples and the like was sampled in a sampling bottle, and 30 mL of ethyl acetate was added. After shaking for 4 hours, the content of the sample bottle was filtered with a 200-mesh stainless steel wire netting, Lt; 0 &gt; C for 2 hours to measure the dry mass. The gel fraction of the pressure-sensitive adhesive layer was determined by the following formula.

Gel fraction (mass%) = (dry mass / mass of the pressure-sensitive adhesive layer) × 100 (%)

[High temperature dead load  exam]

One of the paper separators of the double-faced pressure-sensitive adhesive sheet obtained in Examples and the like was peeled off under conditions of 23 占 폚 and 50% RH, and a polyethylene terephthalate film having a thickness of 25 占 퐉 was laminated on the exposed pressure-sensitive adhesive layer side. Thereafter, another paper separator was peeled off, and the exposed adhesive surface was pressed on a polypropylene plate using a roller of 2 kg. The adhesive area was 20 mm wide x 50 mm. After 20 minutes from the application, the product was kept at 110 캜 for 20 minutes under a drying condition. Thereafter, a load of 100 g was applied perpendicularly to the adhesive layer in the direction of 90 占 and the peel length (mm) after 60 minutes was measured. When the test piece fell from the polypropylene plate within the measurement time, the time required for the drop to fall was measured. When it fell, it was described as "falling".

※ The numerical values of monomer composition, RATF agent, ethyl acetate, L-45, and tackifier are in parts by mass.

Claims (6)

(Meth) acrylic acid ester polymer molecule (a) having a structure represented by the formula (a1) and having a hydroxyl group at both ends of the molecule and having a structural unit derived from a carboxyl group-containing monomer, (Meth) acrylic polymer (A) having a weight average molecular weight (Mw) of 300,000 to 600,000 and a molecular weight distribution (Mw / Mn) of 4.0 or less,
(B) an isocyanate group having two or more isocyanate groups in one molecule in an amount of 0.1 to 5 parts by mass based on 100 parts by mass of the (meth) acrylic polymer (A)
The tackifier (C) having a softening point of 95 DEG C or higher,
Based on the total weight of the pressure-sensitive adhesive composition.

The method according to claim 1,
Wherein the (meth) acrylic polymer (A) is a reversibly adduct cleavage chain transfer (RAFT) polymer of a polymerizable double bond-containing monomer containing a carboxyl group-containing monomer. 3. The method according to claim 1 or 2,
Wherein the (meth) acrylic polymer (A) is a polymer of a polymerizable double bond-containing monomer having an amount of use of a monomer having at least one kind selected from a hydroxyl group and an amino group of 0.3 mass% or less. 4. The method according to any one of claims 1 to 3,
Wherein the (meth) acrylic acid ester polymer molecule (a) is a polymer represented by the formula (A1-1).

[In the formula (A1-1), R ¹ is independently a divalent organic group, and (A) is a divalent group derived from a polymer of a polymerizable double bond-containing monomer each independently containing a carboxyl group-containing monomer .] A pressure-sensitive adhesive layer obtained from the composition for a pressure-sensitive adhesive according to any one of claims 1 to 4. A pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer according to claim 5.