JPH03146582A - Two-pack type adhesive - Google Patents

Abstract

PURPOSE:To obtain the title cold-setting adhesive having a little thickening with time even by adding a crosslinking agent, not causing reduction in tack, consisting of a main agent comprising a mixture of specific copolymer and tackifier resin as a main component and a curing agent comprising a metallic salt of acetylacetone as a main component. CONSTITUTION:The objective adhesive consisting of (A) a main agent comprising a mixture of a water-dispersible copolymer (e.g. copolymer prepared by subjecting ethylene-based or diene-based monomer and unsaturated carboxylic acid to emulsion polymerization in water) containing carboxyl group or hydroxyl group in the molecule and a carboxyl group or hydroxyl groupcontaining tackifier resin (e.g. glycerol ester of polymerized rosin) as a main component and (B) a curing agent comprising a metallic salt of acetylacetone (preferably acetylacetone aluminum salt) as a main component.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a two-component water-dispersible adhesive that cures at room temperature.

<Prior art and problems> Conventionally, cross-linking agents are added to pressure-sensitive adhesives and adhesives made of acrylic copolymers with various functional groups, to strengthen their cohesive force and improve their heat resistance and water resistance. A method is being taken.

For example, when an epoxy compound or incyanate compound is added as a crosslinking agent to an acrylic copolymer or chloroprene polymer that has functional groups such as hydroxyl or carboxyl groups, the viscosity increases over time, which worsens coating workability. did. However, when a metal oxide such as zinc oxide was added as a crosslinking agent, the tackiness decreased and the initial adhesive strength deteriorated.

<Objective of the Invention> An object of the present invention is to provide a two-component water-dispersible adhesive that exhibits little increase in viscosity over time even when a crosslinking agent is added and does not cause a decrease in adhesive strength.

<Disclosure of the Invention> The present invention provides a main ingredient comprising a mixture of a water-dispersible copolymer having a carboxyl group or a hydroxyl group in the molecule and a tackifier having a carboxyl group or a hydroxyl group;
It is a two-component adhesive consisting of a curing agent whose main component is acetylacetone metal salt.

The copolymer having a carboxyl group or a hydroxyl group in the molecule used in the present invention is prepared by combining one or more ethylene and/or diene monomers and one or more unsaturated carboxylic acids in water. It is a copolymer obtained by emulsion polymerization, and the appropriate amount of unsaturated carboxylic acid used is 2 to 30% (by weight) based on the total monomer. Here, the ethylene or diene monomers include ethylene, propylene, phtadiene, isoprene, chloroprene, styrene,
α-methylstyrene, dimethylstyrene, divinyltoluene, vinyl acetate, vinyl propionate, vinyl ether, vinyl chloride, vinylidene chloride, methyl acrylate, ethyl acrylate, n-butyl acrylate, io
- acrylic esters such as butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate,
Examples of unsaturated carboxylic acids include methacrylic acid esters such as methyl methacrylate, 1so-butyl methacrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, and maleic anhydride. can give.

Examples of those having an enclosed hydroxyl group include hydroxyl methyl acrylate and hydroxylethyl acrylate. Among these, those obtained by acid-modifying acrylic ester or chloroprene polymers with acrylic acid or methacrylic acid are most suitable. Next, as the tackifier having a carboxyl group or a hydroxyl group in the molecule, natural or polymerized rosin, modified rosin, and chrycerin ester of hydrogenated rosin,
Rosin-based tackifiers represented by triethylene glycol ester and pentaerythol ester, terpene phenol resins, aliphatic petroleum resins, aromatic petroleum resins, alkyl phenol resins, etc. The main ingredient is a dispersion blended with the water-dispersible copolymer in an amount of 1 to 200 parts in terms of solid content weight.

Next, acetylacetone metal salt is a crystalline powder and has the molecular formula M(CH3C0CHCOCHa)n,
M:=An, Cr, Zn, Cu, Ni, Co, Fe+M
g, Mn fx, etc., and n=2 to 4. Among these, acetylacetone aluminum salt is most suitable in terms of workability and adhesive performance, and its addition amount is suitably 0.1 to 20 PHR.

In the present invention, in addition to the above-mentioned main components, modifiers such as thickeners (water-soluble polymers), film-forming agents (low boiling point solvents), extenders (inorganic fillers), etc. may be optionally used. .

<Operations and Effects of the Invention> In the present invention, the carboxyl group or hydroxyl group in the copolymer and the tackifier, which are the main ingredients, and the acetylacetone metal salt in the curing agent component slowly form at room temperature as shown in the following formula. Because it undergoes a crosslinking reaction, it has little thickening over time and does not cause a decrease in adhesive strength. Show the type.

As described above, metal crosslinking increases molecular weight, increases cohesive force, and improves heat resistance and water resistance.

Next, examples will be explained, where parts indicate parts by weight.

Example 1 2 parts of nonylphenol polyether ammonium sulfate as an emulsifier and 100 parts of water were kept at 80°C and stirred in a flask, and 100 parts of 2-ethylhexyl acrylate, 10 parts of vinyl acetate monomer, and 2 parts of acrylic acid monomer were added. Copolymer 10 was emulsion-polymerized with 2 parts of a 10-polyammonium persulfate aqueous solution as a catalyst for 3 hours while being dropped.
0 parts were mixed with 50 parts of a rosin ester emulsion having a carboxyl group as a tackifier (Arayo Kagaku, Super Ester Emulsion E-720, non-volatile content: 50%) to form a main ingredient.

Next, 2 parts of acetylacetonaluminum salt was added as a hardening agent to 100 parts of the above base resin and stirred.
0 Comparative Example 1 In Example 1, 2 parts of a water-soluble epoxy compound as a hardening agent was added and stirred to prepare an adhesive of Comparative Example 1.

Comparative Example 2 In Example 1, 2 parts of an incyanate compound as a hardening agent was added and stirred to obtain an adhesive of Comparative Example 2.

Comparative Example 3 In Example 1, 50% zinc oxide aqueous dispersion 2 was used as a curing agent.
Comparative Example 4 In Example 1, 100 parts of the copolymer alone except for the tackifier rosin ester emulsion carbon in the base resin was added and stirred to make the adhesive of Comparative Example 3. Then, 2 parts of acetylacetone aluminum salt was added and stirred to obtain an adhesive of Comparative Example 4.

Comparative Example 5 In Example 1, the tackifier added to the main ingredient contained a carboxyl group and a hydroxyl group! An adhesive of Comparative Example 5 was prepared in the same manner except that 50 parts of coumaron indene resin emulsion (non-volatile content: 501%) was used.

The initial viscosity of each of the above adhesives at 20" is set as 100, and the rate of change in viscosity over time after 8 hours and 24 hours (regular), and the adhesive strength according to JIS Z 0237 r Adhesive Tape/Adhesive Sheet Test Method" (180° peeling method,
Table 1 shows the measured values of kyf/25 strength) and tack (ball rolling method, 30 degree inclined plate, NO.).

Table 1 shows that the adhesive of Example 1 of the present invention has a small rate of change in viscosity over time and is excellent in adhesive strength and tack.

Table 1 Measured values

Claims (1)

[Claims] Consisting of a main ingredient consisting of a mixture of a water-dispersible copolymer having a carboxyl group or a hydroxyl group in the molecule and a tackifier having a carboxyl group or a hydroxyl group, and a curing agent whose main ingredient is an acetylacetone metal salt. A two-component adhesive characterized by: