JPS63317575A - Aqueous tacky agent composition - Google Patents

Abstract

PURPOSE:To obtain the titled pollution-free composition bondable even to low- temperature articles or faces having the wet surface by dropwise condensation, etc., by adding polyethyloxazoline to an emulsion of acrylic copolymer. CONSTITUTION:The aimed aqueous tacky agent composition having excellent adhesiveness to faces of dropwise condensation, obtained by adding (D) 5-100 pts.wt. polyethyleneoxazoline to 100pts.wt. emulsion of acrylic copolymer having <=-40 deg.C glass transition point prepared by polymerizing (A) 50-97.9wt.% (meth) acrylic acid ester containing 4-12C alkyl group with (B) 0.1-10wt.% alpha,beta-unsaturated carboxylic acid and (C) 2-49.9wt.% monomer.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applicable to adhesive labels, sheets, stickers, etc. (hereinafter referred to as
This invention relates to an aqueous adhesive composition used for adhesive tapes and adhesive tapes.

(Prior Art) In recent years, adhesive tape labels have become widespread and are widely used in office work, manufacturing, distribution, transportation, medical care, and other fields. The adhesives used for these labels and tapes include solvent-based adhesives obtained by polymerizing acrylic esters in a solvent, and water-based adhesives obtained by emulsion polymerizing acrylic esters in a water phase.
Emulsion-based adhesives are well known.

Among these, solvent-based adhesives have recently become non-polluting, water-based adhesives because the solvents contained in them pose problems such as fires, air pollution, and water pollution during the process of applying them to labels, tapes, etc. Adhesives are being replaced.

On the other hand, the scope of application of labels and tapes is expanding, and there are demands for adhesion to low-temperature surfaces, adhesion to difficult-to-adhesive adherends such as polyolefin, and adhesion to rough surfaces.

Furthermore, with the spread of frozen foods, the frequency of pasting price tags on items and bundling low-temperature items is increasing. When attaching a lapel or cheese to an item that is to be stored at a low temperature, some of these frozen foods may be brought back to room temperature from the low temperature, resulting in condensation on the surface to which they are attached. In the case of solvent-based adhesives, the adhesive surface is water repellent, so it has a certain degree of adhesion even on dew condensation surfaces, but in the case of water-based adhesives, the emulsifiers, thickeners, etc. contained therein Due to the water-soluble component of the adhesive, the adhesive surface gets wet with water and forms a thin film of water between the adhesive and the adherend, resulting in insufficient adhesion.

(Problems to be Solved by the Invention) The present invention is useful for converting from solvent-based adhesives, which have problems such as pollution, to non-polluting water-based adhesives. The purpose of the present invention is to provide a water-based adhesive that can be applied to surfaces.

(Means for solving the problem) As a result of intensive studies in response to social demands for a water-based adhesive with excellent adhesion to dew-condensing surfaces, we found that (1) (al) an alkyl group having 4 to 12 carbon atoms. 50 to 97.9 parts by weight of acrylic ester or methacrylic ester, (b) 0.1 to 10 parts by weight of α, β unsaturated cargonic acid, (C) Other monomers copolymerizable with the above monomers. body 2-4
9.9% by weight, an emulsion of an acrylic copolymer with a glass transition point of -40°C or lower, invention has been achieved.

In the present invention, the acrylic ester or methacrylic ester having an alkyl group having 4 to 12 carbon atoms is
It refers to butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate. Preferred are butyl acrylate, 2-ethylhexyl acrylate, and the like. During the polymerization of copolymer (A), (meth) in the monomer
When the acrylic ester content is less than 50% by weight, sufficient adhesive strength as an adhesive cannot be obtained, and when it exceeds 97.9% by weight, sufficient holding power cannot be obtained. Preferably 6
It is 0 to 95% by weight.

α, β unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, and the like. Preferred are acrylic acid, itaconic acid, and maleic acid. The amount of these monomers used is 0.1 to 10% by weight; if it is less than 0.1% by weight, sufficient holding power cannot be obtained;
If it exceeds this, the adhesive strength will decrease. Preferably 0.3~
It is 5% by weight.

Monomers that can be copolymerized with the above monomers include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, hydroxyalkyl (meth)acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, and glycidyl (meth)acrylate. ) acrylate, (meth)acrylamide, styrene, acrylonitrile.

Examples include N-methylolacrylamide and vinyl acetate. The amount of these copolymerizable monomers used is 2 to 49.9% by weight; if it is less than 2% by weight, sufficient holding power will not be obtained, and if it exceeds 49.9% by weight, sufficient adhesive strength will not be obtained. I can't get it.

Polymerization of these monomers is carried out by a conventional emulsion polymerization method. The glass transition point of the acrylic copolymer obtained by polymerization is -4
It is necessary that the temperature is below 0°C, preferably below -50°C,
If the temperature is higher than -40°C, tack cannot be obtained.

In this emulsion polymerization, polyoxyethylene noni/17 phenyl ether, lauryl sulfate, dodecylbenzenesulfonate are used as emulsifiers, persulfates, polymerization initiators such as azobisin butyronitrile, butyl mercaptan, inzolobil, etc. Molecular weight regulators such as alcohol, methanol, carbon tetrachloride, antifoaming agents, thickeners, etc. as necessary.
Additives such as preservatives are co-dispersed and emulsified in water and copolymerized, generally under an inert gas atmosphere.

Note that the glass transition point is determined by the following formula.

1/Tg=Σ(Wi/Tgi) Here, Tg: Glass transition point (absolute temperature display) of the copolymer Tgi
: Glass transition point (absolute temperature display) of the homopolymer of monomer component 1) Wl: Weight fraction of component (1) in the copolymer (Jew. Prandrag et al., ed., "Polymer...0 Book") ”, J. Wiley Publishing, 2nd edition (J. Brandru
p et al, ” Polymer Handb
ook”, J.

Wiley, 2'ad, ) The polyethyloxazoline used in the present invention is a water-soluble polymer obtained by polymerizing 2-ethyl-2-oxazoline. The number average molecular weight is preferably 300.000 or less. The amount of polyethyloxazoline to be blended is 5 to 100 parts by weight, preferably 10 to 70 parts by weight, based on 100 parts by weight of the solid content of the acrylic copolymer. If the amount exceeds 100 parts by weight, adhesive strength and tack cannot be obtained.

The aqueous pressure-sensitive adhesive composition of the present invention may further contain a thickener, an antifoaming agent, a tackifier, a pigment such as titanium oxide, a wicking agent, and the like.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Note that parts and parts are based on weight.

Examples 1-7, Comparative Examples 1-5 (Emulsion Polymerization) Monomer mixtures having the compositions shown in Tables 1 and 2 were emulsion polymerized by the following method.

40 parts of water and 0.1 part of ammonium persulfate were charged into an autoclave equipped with a stirrer, a temperature regulator, and a reflux condenser, and then 100 parts of a monomer mixture having the composition shown in Tables 1 and 2, and dodecylbenzenesulfonic acid. After adding 1.0 part of soda, 1.0 part of polyoxyethylene nonylphenyl ether, and 60 parts of water, the mixture was stirred and emulsified to prepare a pre-emulsion.

The entire amount of this Daret emulsion was continuously added to an autoclave over 8 hours while stirring at 80° C. to carry out emulsion polymerization. Thereafter, stirring was further continued at 80° C. for 2 hours to achieve a polymerization conversion of about 98 coefficients or more, and an acrylic copolymer emulsion was obtained.

(Preparation of water-based adhesive composition) The acrylic copolymer emulsion was adjusted to pH with ammonia water.
8.5, and added sodium polyacrylate (manufactured by Rohm Haas Co., Ltd., trade name: ASE-60) to measure the viscosity (Brookfield viscometer, I64 spindle, 6rp
m) was adjusted to 2×10′ cp.

Then / ethyloxazoline (Dow Chemical Exhibition XAS
-10874) in the proportions shown in Tables 1 and 2 to prepare an aqueous adhesive composition.

(Evaluation of Aqueous Adhesive Composition) (i) Preparation of Adhesive Test Piece The aqueous adhesive composition prepared as described above was applied to release paper, dried, and then transferred to high-quality paper. After curing for a week,
A test piece was prepared by cutting it into a predetermined size.

(1 stitch Measurement of Adhesive Strength The above test piece was attached to a stainless steel plate (5US304), and the adhesive strength was measured according to the method of JIS-20237. The unit is the load per 25 mm.

(iii) Measurement of adhesion on dew condensation surface Stainless steel plate (5US304 size 50m x 125
mX 2 rsw, ) to -10°C, and then:
Place in an atmosphere of 23°C x 651RH. After about 3 minutes, the above test piece was pasted onto the surface of the SUS board on which dew had adhered, and was pressed with a 2Kt roll, and immediately a peel test was performed at a speed of 300m1w1n. The unit is the load per 25n+.

(1) This is an index representing ball tack adhesion, and was measured by the method of JIS-20237. The units are expressed in ball tombs.

(V) Retention force The above test piece was measured by the method of JIS-20237. The unit is expressed in time (hours) until it falls.

Evaluation results Examples are shown in Table-1 and Table-2.

Examples 1 to 7 of the present invention all showed excellent performance in adhesion, tack, holding power, and adhesion to dew condensation surfaces.

Comparative Example 1 is a case where the acrylic acid ester having an alkyl group having 4 to 12 carbon atoms has 50 grooves, adhesive strength,
Tack is inferior.

Comparative Example 2 is a case where the acrylic acid ester exceeds 97.9 degrees, and the holding power is poor.

In Comparative Example 3, the α,β unsaturated carboxylic acid content was less than 0.1%, and the holding power was poor.

In Comparative Example 4, when the amount of polyethyl oxazoline was less than 5 parts by weight with respect to the acrylic copolymer 1001 base portion, the dew condensation surface adhesion was poor.

In Comparative Example 5, the tack was also poor in the case where polyethyloxazoline exceeded 100 parts by weight.

(Effect of the invention) The aqueous adhesive composition of the present invention has excellent adhesive performance,
In addition, it has excellent adhesion to dew-condensing surfaces.

Procedural amendment 1986 1 JJ 22nd

Claims (1)

[Claims] (1) (a) Acrylic ester or methacrylic ester having an alkyl group having 4 to 12 carbon atoms 50 to 9
7.9% by weight, (b) 0.1 to 10% by weight of α,β unsaturated carboxylic acid, (c) 2 to 49% of other monomers copolymerizable with the above monomers.
An aqueous adhesive characterized by containing 5 to 100 parts by weight (solid content) of polyethyloxazoline per 100 parts by weight of an emulsion of an acrylic copolymer having a glass transition point of -40°C or less obtained by polymerizing 9% by weight of agent composition