GB1123360A - Thickening of alpha-cyanoacrylates - Google Patents

Abstract

Adhesive compositions are prepared by (a) subjecting at least one monomeric alpha-cyanoacrylate ester, which is essentially free of any free-radical polymerization inhibitor and which is stabilized against autopolymerization by the presence of an anionic polymerization inhibitor, to free-radical polymerization conditions; and (b) adding a free-radical polymerization inhibitor to the mixture when the viscosity at 25 DEG C. of the partially polymerized cyanoacrylate ester(s) is within the range of 50 to 50 x 105 centipoises. The compositions are then applied to materials which are to be bonded together, and subjected to anionic polymerization conditions (e.g. presence of moisture), whereby the polymerization of cyanoacrylate ester(s) is completed. Suitable alpha-cyanoacrylate esters include alkyl, cycloalkyl, alkenyl (e.g. allyl), aryl and aralkyl esters. Inhibitors of anionic polymerization include Lewis Acids such as SO2, BF3 or HF. Step (a) polymerization may be initiated by a peroxide, e.g. benzoyl peroxide, an azo compound, e.g. azobisisobutyronitrile, or by radiation, e.g. heat, U.V. light, X-rays, gamma-rays or electron rays. Another monomer, or low molecular polymer thereof, may be included in step (a), e.g. styrene, vinyl acetate, methyl methacrylate, acrylonitrile, ethyl acrylate, vinylidene cyanide and vinyl chloride. The inhibitor used in step (b) may be, for example, hydroquinone or butylated hydroxy-toluene (2,6-di-t-butyl-p-cresol). The adhesive compositions are suitable for bonding animal tissue or organs, and materials such as wood, metal, glass, leather and rubber.