JPS58196277A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:To prepare the titled composition having improved adhesivity to polyethylene, etc. while keeping the cohesivity, by compounding a specific 2-phenoxyethyl (meth)acrylate derivative to a mixture of a specific acrylic ester monomer, etc. and an unsaturated dicarboxylic acid monomer, etc. CONSTITUTION:The objective composition is prepared by adding (A) 5-35wt% of a 2-phenoxyethyl (meth)acrylate derivative of formula (R1 is H or CH3; R2 is H or 1-4C alkyl) to (B) a composition composed of (i) 60-90wt% of an acrylic acid ester containing 4-10C alkyl group or its mixture with a (meth)acrylic acid ester monomer containing <=3C alkyl group and/or vinyl acetate monomer and (ii) 0.1-5wt% of an unsaturated mono- or di-carboxylic acid monomer, and polymerizing the composition. EFFECT:It has excellent adhesivity to nonpolar adherend.

Description

DETAILED DESCRIPTION OF THE INVENTION To this end, Ming is able to obtain a 1'
) An object of the present invention is to provide an acrylic ester pressure-sensitive adhesive composition that has improved adhesive strength to polar adherends.

Pressure sensitive adhesives are evaluated by cohesive strength, which governs tack, adhesion, and durability of the adhesive.

Incidentally, adhesive force is a force that indicates instantaneous wettability to an adherend, adhesive force is a peeling force from an adherend, and cohesive force is a force that causes the adhesive itself to cohere. In order for a pressure-sensitive adhesive to exhibit practically sufficient adhesive properties, it is desirable that both adhesive force and cohesive force be large; however, in general, adhesive force, adhesive force, and cohesive force are It is a property that is contradictory to force, and when the adhesive force is improved, the cohesive force decreases, and conversely, when the cohesive force is improved, the adhesive force tends to decrease. Therefore, it would be ideal to strike a balance where both are excellent, but it is extremely difficult.

Therefore, it seems that depending on the application of the adhesive, it is considered whether adhesive force or cohesive force is more important, and the appropriate measures are taken accordingly. This also applies to commonly used rubber-based and acrylic ester-based (2) adhesives.

By the way, rubber-based pressure-sensitive adhesives, including non-polar ones such as polyethylene, have adhesion properties to the adherend of the long sword, but over time, oxidative deterioration causes adhesive strength and cohesion to deteriorate. The problem is that the power decreases. On the other hand, acrylic ester-based pressure-sensitive adhesives have a basic composition of higher acrylic ester having an alkyl group having 4 to 10 carbon atoms, and acrylic acid having a lower alkyl group having 3 or less carbon atoms ( or methacrylic acid) ester monomer or/
It is constructed by copolymerizing an unsaturated mono- or dicarboxylic acid monomer with an equivalent amount or less of vinyl acetate monomer, and there is no problem of oxidative deterioration unlike rubber-based products. However, it has the disadvantage of lacking adhesion to nonpolar adherends such as polyethylene. Therefore, the present inventors are working hard to develop an acrylic ester-based pressure-sensitive adhesive that can exhibit good adhesive strength even to non-polar adherends such as polyethylene without reducing cohesive strength. As a result of my research, I developed this invention (3).

That is, the present invention provides an acrylic ester monomer having an alkyl group having 4 to 10 carbon atoms, or the above-mentioned acrylic ester monomer, an acrylic ester monomer having an alkyl group having 3 or less carbon atoms, and 3 or less carbon atoms. 60 to 90% by weight of a mixture of acrylic (or methacrylic) ester monomers and/or vinyl acetate monomers having an alkyl group and 0.1% of a monounsaturated mono- or dicarboxylic acid monomer.
5% by weight of a 2-phenoxyethyl (meth)acrylate derivative represented by R/ (R1 is H or CH3, Rz is H or an alkyl group having 1 to 4 carbon atoms). It is characterized in that it is blended in an amount of ~35% by weight and copolymerized.

In the above structure, the composition excluding the 2-phenoxyethyl (meth)acrylic-F derivative represented by the formula Tl1 is known, and as described above, it is suitable for non-polar adherends such as (4) polyethylene. However, the reason why it exhibits excellent adhesion when copolymerized with the 2-phenoxyethyl (meth)acrylate derivative represented by formula (1) is not necessarily clear. However, this is probably because the wettability to the adherend is improved and the contact condition at the interface is improved.

Therefore, the amount of the 2-phenoxyethyl (meth)acrylate derivative represented by formula (11) in other compositions is within the range of 5 to 35% by weight, preferably 15 to 25% by weight. Incidentally, if this amount is less than 5% by weight, the cohesive force will decrease and adhesive will remain on the adherend when peeled off.If it is more than 35% by weight, the cohesive force will be too high and the adhesiveness will decrease. , it can no longer be used as a pressure sensitive adhesive.

In the structure of the present invention, the constituent parts excluding the 2-phenoxyethyl (meth)acrylate derivative represented by formula 11),
The basic composition of the adhesive is an acrylic ester monomer having an alkyl group having 4 to 10 carbon atoms. Octyl acid, etc. are used. However, these substances
When used alone, it has low viscosity and is not suitable as a pressure-sensitive adhesive, so it is generally combined with an acrylic acid (or methacrylic acid) ester monomer having an alkyl group of 3 or less carbon atoms or/and vinyl acetate. It is common to use monomers in combination to increase viscosity. In this case, acrylic acid (or methacrylic acid) having an alkyl group with 3 or less carbon atoms
As the ester monomer, methyl acrylate, ethyl acrylate, methyl methacrylate, etc. may be used alone or in combination of two or more. When used in combination with ester,
It is desirable to use less than the equivalent amount in order to prevent a decrease in adhesive strength.

In the present invention, the proportion of these components in the total copolymer composition is 60 to 90%, preferably 70%.
It is used so that the overlap is ~80%.

As the unsaturated mono- or dicarboxylic acid monomer (6), acrylic acid, methacrylic acid, itaconic acid, maleic acid, etc. are used, and the proportion thereof in the total copolymer composition is 0.1 to 5% by weight. It is usually used in an amount of preferably 0.5 to 2% by weight.

In the present invention, in order to increase the cohesive force to the extent that the adhesiveness to nonpolar adherends is not reduced, monomers having a plurality of ethylenic double bonds, such as diallyl maleate and ethylene glycol dimethacrylate, are used. , 1.6 hexanediol diacrylate, or functional group-containing monomers such as glycidyl methacrylate, hydroxyethyl acrylate, N-methylol acrylamide, etc., may also be copolymerized together.

The pressure-sensitive adhesive composition of the present invention is emulsion polymerized! ! !
! Polymerization can be carried out by methods such as turbid polymerization, solution polymerization, and bulk polymerization, but emulsion polymerization and solution polymerization are generally preferred. By the way,
The emulsion polymerization method uses emulsifiers such as (7) adducts of alkylphenols, higher alcohols and ethylene oxide, sulfuric acid esterification thereof, or block polymers of polyethylene oxide and polypropylene oxide, potassium persulfate, ammonium persulfate, A method is adopted in which the monomer or monomers are emulsified with the above emulsifier and added to an aqueous solution containing a water-soluble polymerization initiator such as hydrogen peroxide. In the solution polymerization method, a monomer and azobisisobutyronitrile, benzoyl peroxide are mixed in an aromatic solvent such as Hensen or toluene, a ketone such as acetone, methyl ethyl ketone, or an ester solvent such as ethyl acetate. A method is adopted in which polymerization is carried out by adding a polymerization initiator such as.

The pressure-sensitive adhesive composition according to the present invention thus constituted may contain additives such as fillers, plasticizers, tackifiers, binders, wetting agents, antifoaming agents, etc., if necessary. You can also do that.

Therefore, when the pressure-sensitive adhesive composition according to the present invention is applied to a support such as high-quality paper, cast-coated paper, synthetic resin film, cloth, etc. It is possible to obtain a pressure-sensitive adhesive sheet that exhibits practically good adhesive strength without reducing cohesive strength even to non-polar adherends such as polyethylene, which adhesives lack.

The present invention will be described below with reference to Examples, but it goes without saying that the scope of the present invention is not limited only to these Examples.

Example 1 320 g of 2-ethylhexyl acrylate, 76 g of 2-phenoxyethyl acrylate, 4 g of acrylic acid, n
- 0.4 g of dodecyl mercaptan, 5 g of polyoxyethylene nonylphenol ether emulsifier, 5 g of oxyethylene/oxypropylene bronok polymer emulsifier,
Emulsifying monomer mixture (170 cc of ion-exchanged water)
). 7. Into a container equipped with a stirrer, a temperature needle, a reflux condenser, and a dropping funnel, 240 cc of ion-exchanged water, 2 g of the above 1:1 emulsifier mixture, and 0.8 g of potassium persulfate are charged, and the mixture is heated while purging with nitrogen. When the liquid temperature reaches 70°C, add 1/6 (9) of the emulsified monomer mixture in (1). When the reaction rate reaches 90%, the remaining emulsified monomer mixture (1) is added over 2 hours and polymerized. After the addition is complete, stirring is continued at 70° C. for 2 hours to complete the reaction.

The emulsion thus obtained had a solids content of 50% and a viscosity of 100 cps. Cast this emulsion on coated paper (manufactured by Kanzaki Paper Co., Ltd., product name ``Mirror Coat'')
The adhesive sheet was coated and dried to a dry weight of 25 g/n.A release paper laminated with polyethylene was layered on the adhesive-coated surface and bonded to create an adhesive sheet.The adhesive sheet thus obtained was The adhesive strength and cohesive strength of the sample to polyethylene were as shown in the attached table.

Example 2 In the same manner as in Example 1, copolymerization was carried out in the ratio of 2-ethylhexyl acrylate: 2-phenoxyethyl acrylate: vinyl acetate: acrylic acid = 80:14:5:l to obtain an emulsion. An adhesive sheet was created using a method. The adhesive strength and cohesive strength of this sheet were as shown in the attached table.

(10) Example 3 In the same manner as in Example 1, an emulsion was prepared by copolymerizing 2-ethylhexyl acrylate: 2-phenoxyethyl methacrylate: methyl acrylate: acrylic acid at a ratio of 74:15:10:1. was obtained, and an adhesive sheet was prepared in the same manner.

The adhesive strength and cohesive strength of this sheet were as shown in the attached table.

Example 4 In the same manner as in Example 1, an emulsion was obtained by copolymerizing 2-ethylhexyl acrylate: 1-(4-butylphenoxy)-ethyl acrylate: acrylic acid at a ratio of 80:19:l. An adhesive sheet was created in a similar manner. The adhesive strength and cohesive strength of this sheet were as shown in the attached table.

Comparative Example 1 In the same manner as in Example 1, 2-ethylhexyl acrylate: methyl acrylate: acrylic acid = 80:19:
An emulsion was obtained by copolymerizing at a ratio of 1:1, and a pressure-sensitive adhesive sheet was prepared in the same manner.

(11) The adhesive strength and cohesive strength of this sheet were as shown in the attached table.

Comparative Example 2 In the same manner as in Example 1, 2-ethylhexyl acrylate: ethyl acrylate: vinyl acetate: acrylic acid =
An emulsion was obtained by copolymerizing at a ratio of 75:19:5:l, and a pressure-sensitive adhesive sheet was prepared in the same manner. The adhesive strength and cohesive strength of this sheet were as shown in the attached table.

Comparative Example 3 In the same manner as in Example 1, 2-ethylhexyl acrylate:methyl methacrylate:acrylic R4=68:3
An emulsion was obtained by copolymerizing at a ratio of 0:2, and a pressure-sensitive adhesive sheet was prepared in the same manner.

The adhesive strength and cohesive strength of this sheet were as shown in the attached table.

(12) (Appended table) Adhesive force measurement method i According to J I 5-Z-1538,
In a room at 20°C and 60% RH, an adhesive sheet was pasted twice with a 2 kg roller, and after 2 hours it was peeled off at a 180° angle using an Instron type tensile tester at a pulling speed of 3 Q Q w / min. The adhesion force was measured.

Cohesive force measurement method: Place the sample on a steel plate at 2.5 cIIIX
2.5 (13) After pasting with the area of the mouth and pressing with a 2 kgO roller, the surface was held vertically during pasting, a load of 1 kII was applied to the sample, and the time until the sample slipped off was measured in units of time.

Patent applicant: Kanzaki Paper Co., Ltd. (1 move)

Claims (1)

[Scope of Claims] An acrylic ester monomer having an alkyl group having 4 to 10 carbon atoms or an acrylic ester monomer having an alkyl group having 3 or less carbon atoms and an acrylic acid (or methacrylic) ester monomer having an alkyl group having 3 or less carbon atoms. 60 to 90% by weight of a mixture of monomer or/and vinyl acetate monomer, and 0.1 to 5% of an unsaturated mono- or dicarboxylic monomer. A set consisting of % by weight.
A pressure-sensitive adhesive composition comprising 5 to 35% by weight of a 2-funoxy 1-tyl (meth)acrylate derivative (alkyl group having ~4 carbon atoms) and copolymerized.