JPH06104815B2 - Water-dispersed adhesive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a room temperature curing type two-part water-dispersible pressure-sensitive adhesive.

<Prior Art> Conventionally, there has been a method of increasing heat resistance and water resistance by adding a cross-linking agent to a pressure-sensitive adhesive or adhesive obtained by adding various functional groups to an acrylic copolymer or the like to increase cohesive force. Has been.
For example, when an epoxy compound or an isocyanate compound was added as a cross-linking agent to an acrylic copolymer or chloroprene polymer having a functional group of a hydroxyl group or a carboxyl group, the viscosity increased with time and the coating workability deteriorated. . Further, when a metal oxide such as zinc oxide was added as a cross-linking agent, the tackiness decreased and the initial adhesive strength deteriorated.

<Purpose of the Invention> An object of the present invention is a two-pack type water-dispersible pressure-sensitive adhesive that does not increase in viscosity with time even when a cross-linking agent is added and does not cause a decrease in adhesive strength.

<Disclosure of the Invention> The present invention is an aqueous dispersion comprising a main agent containing a water-dispersible linear copolymer having a carboxyl group or a hydroxyl group in the molecule as a main component, and a crosslinking agent containing an acetylacetone metal salt as a main component. It is a type adhesive.

The linear copolymer having a carboxyl group in the molecule used in the present invention is one or more kinds of ethylene-based and / or diene-based monomers and one or more kinds of unsaturated carboxylic acid in water. It is a substantially linear copolymer obtained by emulsion polymerization, and the amount of unsaturated carboxylic acid to be used is appropriately 2 to 30% (weight) based on the total monomers. Here, as the ethylene-based or diene-based monomer, ethylene, propylene, butadiene, isoprene, chloroprene, styrene, α-methylstyrene, dimethylstyrene, divinyltoluene, vinyl acetate, vinyl propionate, vinyl ether, vinyl chloride, vinylidene chloride, Methyl acrylate, ethyl acrylate, n-butyl acrylate,
Acrylic esters such as iso-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n
-Butyl methacrylate, iso-butyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid esters such as lauryl methacrylate, and the like, and unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic anhydride, and the like. To be
Among these, a polymer obtained by acid-modifying a polymer of acrylic acid ester or chloroprene with acrylic acid or methacrylic acid is most suitable. Next, acetylacetone metal salt is a crystalline powder, an intramolecular complex salt type chelate compound having various colors depending on the difference in the valence of the metal ion, and is represented by the molecular formula M (CH ₃ COCHCOCH ₃ ) n. , M = Al, Cr, Zn, Cu, N
i, Co, Fe, Mg, Mn, etc., where n = 2-4. Among these, acetylacetone aluminum salt is the most suitable in terms of workability and adhesive performance, and the addition amount thereof is suitably 0.5 to 20 PHR.

In the present invention, since the crosslinking of the carboxyl group or hydroxyl group in the molecule with the acetylacetone metal salt proceeds slowly at room temperature as shown in the following formula, the viscosity increase with time is small and the adhesive strength is not lowered.

In addition, Represents a linear copolymer, and M represents a metal as described above.

As described above, the metal cross-linking increases the molecular weight, strengthens the cohesive force, and improves heat resistance and water resistance.

Next, an example and a comparative example will be described.

Example 1 Comparative Examples 1, 2, and 3 In a flask, 2 parts of nonylphenol polyether ammonium sulfate as an emulsifier and 100 parts of water were stirred while maintaining the temperature at 80 ° C., and 100 parts of 2-ethylhexyl acrylate, 10 parts of vinyl acetate monomer and acrylic acid were mixed. 2 parts of the monomer and 2 parts of a 10% aqueous solution of ammonium persulfate as a catalyst were added dropwise over 3 hours, and emulsion polymerization was performed to obtain a main agent. Next, this main ingredient 100
2 parts of acetylacetone aluminum salt as a cross-linking agent was added to each part and stirred to obtain the adhesive of Example 1. In addition, Comparative Example 1 was prepared by adding and stirring 2 parts of a water-soluble epoxy compound.
Similarly, Comparative Example 2 with 2 parts of isocyanate compound and Comparative Example 3 with 2 parts of 50% zinc oxide dispersion liquid
Adhesive of

With these initial viscosities at 20 ° C. taken as 100, the rate of change in viscosity with time after 8 hours and 24 hours, and the adhesive strength according to JIS Z0237 “Adhesive tape / adhesive sheet test method” (180
Table 1 shows the measured values of the peeling-off method, kgf / 25 mm width), and tack (ball rolling method, 30-degree inclined plate, No.).

Example 2 Comparative Examples 4,5,6 2 parts of nonylphenol polyether ammonium sulfate emulsifier and 100 parts of water were stirred in a flask while maintaining the temperature at 80 ° C. to obtain 80 parts of ethyl acrylate monomer, 20 parts of vinyl acetate monomer and acrylic acid monomer. 2 parts with 10% of the catalyst
With 2 parts of ammonium persulfate aqueous solution, emulsion polymerization was carried out for 3 hours to prepare a main agent. Then, 2 parts of acetylacetone aluminum salt as a cross-linking agent was added to 100 parts of this main agent and stirred to obtain an adhesive of Example 2. Further, 2 parts of a water-soluble epoxy compound was added and stirred to obtain an adhesive of Comparative Example 4, and similarly, an adhesive of 2 parts of an isocyanate compound was used in Comparative Example 5
The adhesive of Comparative Example 6 was 2 parts of 50% zinc oxide dispersion.

With these initial viscosities at 20 ° C as 100, the rate of change in viscosity with time after 8 hours and 24 hours, and the contact adhesiveness (yes or nothing) and the adhesive strength (tensile shear strength; kg / kg) under the following adhesive conditions cm ^2, 180 ° peel strength; kg / measurements of 25mm width) second
Shown in the table.

Adhesion conditions Coating amount 120g / m ² (per side), double-sided adherend Tensile shear strength; Plywood × steel plate 180 degree peeling; No. 9 campus × aluminum plate Drying 80 ℃, 3 minutes Pressing 3kg / cm ² , 5 seconds Curing 7 days, room temperature Measurement temperature 20 ℃, 60 ℃

Claims (1)

[Claims] 1. A main agent containing a water-dispersible linear copolymer having a carboxyl group or a hydroxyl group in the molecule as a main component, and a cross-linking agent containing an acetylacetone aluminum salt as a main component. A water-dispersible pressure-sensitive adhesive, characterized in that the carboxyl group or hydroxyl group of the polymer and the metal salt are mixed in a molar ratio of 1: 0.5 to 8.