Anaerobic compositions with enhanced toughness and crack resistance

This invention relates to anaerobic adhesive compositions, the reaction products of which demonstrate enhanced toughness and resistance to crack propagation. More particularly, the reaction products of the present invention exhibit increased toughness after exposure to thermal shock, while retaining their room temperature performance properties. An anaerobic adhesive composition having enhanced toughness and resistance to crack propagation, particularly subsequent to thermal exposure, comprising a combination of three monomers consisting of (a) at least one (meth) acrylate monomer, (b) at least one (meth)acrylate-terminated urethane modified acrylonitrile/butadiene prepolymer, and (c) at least one (meth)acrylate-terminated acrylic/polyisocyanate adduct.