Adhering polyurethane to metal

Adhesive compositions for cementing polyurethane resins to metals comprise an admixture of a greater amount of a polyvinyl resin and an organic polyisocyanate. The resin may be polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylidene chloride, polyvinyl formal, mixtures thereof or copolymers of the corresponding monomers. Many suitable polyisocyanates are listed and the examples describe the use of adhesives comprising polyvinyl chloride and polymethylene polyphenylisocyanate. Many substances suitable for the preparation of the polyurethane resins are listed, and the reaction may be promoted by catalysts or accelerators, e.g. 1,4-butane diol, N-methyl morpholine, dimethyl ethanolamine, triethylamine, N,N1-diethylcyclohexylamine, N,-N1-dimethylcyclohexylamine, dimethylhexahydroaniline, diethylhexahydroaniline and cobalt naphthenate. In Example II the preparation of a polyurethane by reacting ethylene glycol and adipic acid to form a polyester, reacting the polyester with diphenylmethane- -4,41-diisocyanate, and subsequently adding hydroquinone as catalytic cross-linker. The adhesive compositions may be used in the manufacture of top lifts for shoes.ALSO:Toplifts for shoes comprise polyurethane resin cemented to metal nails by means of an adhesive composition comprising a p polyvinyl resin in greater amount admixed with an organic polyisocyanate. The toplifts are preferably moulded and cemented in a single step by coating the head of the nail with the adhesive and locating it in the mould of an injection moulding machine, the shank of the nail being located in a well in the wall of said mould, and subsequently injecting the polyurethane resin so that it is simultaneously moulded and cemented to said pail head.