1984

a-cyanoacrylate compounds expressed by the following general formula: wherein R' desianates- and R2 designates alkyl groups, alkenyl groups or alkynyl groups of C1 to C4. These compounds are preferably synthesized by the reaction of the compounds expressed by the following general formula: wherein R' and R2 are same as the above described, with formaldehyde products and then the depolymerization of the resulting dehydrating condensation polymers. These compounds are effectively used as fast-setting adhesives.

The green strength of polymers produced by emulsion polymerization processes is improved through the use of carboxyl containing compounds. Specifically, the compounds are half esters of unsaturated dicarboxylic acids wherein the half ester moiety renders the carboxyl containing compound hydrophobic. As a result, carboxylic copolymers can be produced in emulsion polymerizations having a basic (pH.gtoreq.7.0) aqueous medium. Heretofore, use of carboxylic acids in emulsion polymerizations have been limited to acidic mediums.

Disclosed are cyanoacrylate adhesive compositions containing elastomeric polymers as fillers. Preferred fillers are the acrylic rubbers. Filler concentration range from about 0.5-40% by weight of the composition. Beneficial results include improved toughness of the cured compositions, as measured by impact, peel and tensile strength properties, particularly after exposure elevated temperatures which would ordinarily severely degrade the adhesive strength.

A cyanoacrylate-based adhesive composition comprises 55-92% by weight of a 2-cyanoacrylate ester, preferably the ethyl ester, from 40-30% by weight of a vinyl chloride/vinyl acetate copolymer and not more than 25% by weight of a plasticizer (the plasticizer may be omitted entirely). The copolymer is preferably a vinyl chloride/vinyl acetate/maleic acid terpolymer.

A cyanoacrylate-based adhesive composition comprises 55-92% by weight of a 2-cyanoacrylate ester, preferably the ethyl ester, from 40-30% by weight of a vinyl chloride/vinyl acetate copolymer and not more than 25% by weight of a plasticizer (the plasticizer may be omitted entirely). The copolymer is preferably a vinyl chloride/vinyl acetate/maleic acid terpolymer.

Cyanoacrylate compositions which employ fumed silicas treated with polydimethylsiloxane or trialkoxyalkylsilane are stable and exhibit an unexpectedly high thixotropic ratio. Such compositions are useful in adhesive applications or, when stabilized so as to prevent polymerization in contact with moisture, in latent fingerprint developing applications.

An adhesive composition comprising an adhesive base and accelerator portion, the adhesive base comprising (a) a polymerizable monomer selected from the group consisting of unsubstituted alpha-cyanoacrylates and substituted alpha-cyanoacrylates; and (b) an effective amount of stabilizer; and the accelerator portion comprising a weakly acidic or weakly basic ionic accelerator compound comprising a cation M and an anion A, the pKa relating to cation M in the equilibrium defined by M(H2O) + = MOH + H+ being at least about 10, the pKa relating to anion A in the equilibrium defined by HA= A- + H+