Method of bonding employing an adhesive composition containing polyisocyanate reaction products having an available isocyanate content of not more than 0.5 percent

Claim 1

A method of bonding a segmented copolyester thermoplastic elastomer composition consisting essentially of a multiplicity of recurring long chain ester units and short chain ester units joined head-to-tail through ester linkages and a flexible or nonflexible substrate which comprises applying to at least one of said segmented copolyester elastomer or said substrate an adhesive lacquer system comprising organic solvent-carried thermoplastic polyetherurethane, said polyetherurethane having substantially no free hydroxyl moieties and a residual free isocyanate content of no greater than 0.5 percent, said polyurethane being obtained by forming an isocyanate-functional intermediate by reacting an excess of at least one polyisocyanate having at least two isocyanate groups with at least one polyether polyol having at least two hydroxyl groups in an adhesive solvent system until at least about 90 percent of said hydroxy groups have reacted with said isocyanate groups, reacting said isocyanate-functional intermediate in said adhesive solvent system with not more than a stoichiometric amount of at least one difunctional chain extending reagent to a viscosity endpoint corresponding to a molecular weight in the range from about 20,000 to about 200,000 at a residual free isocyanate content not exceeding 0.5 percent by weight based on weight of said polyurethane, and terminating such reaction; contacting said elastomer and said substrate; and maintaining such contact at a temperature and pressure and for a time sufficient to effect curing of said thermoplastic polyurethane adhesive system.

Claim 2

A method of bonding a segmented copolyester thermoplastic elastomer composition consisting essentially of a multiplicity of recurring long chain ester units and short chain ester units joined head-to-tail through ester linkages and a flexible or nonflexible substrate which comprises applying to at least one of said segmented copolyester elastomer or said substrate an adhesive lacquer system comprising organic solvent-carried thermoplastic polyetherurethane, said polyetherurethane having substantially no free hydroxyl moieties and a residual free isocyanate content of no greater than 0.5 percent, said polyurethane being obtained by forming an isocyanate-functional intermediate by reacting an excess of at least one polyisocyanate having at least two isocyanate groups with at least one polyether polyol having at least two hydroxyl groups in an adhesive solvent system until at least about 90 percent of said hydroxy groups have reacted with said isocyanate groups, reacting said isocyanate-functional intermediate in said adhesive solvent system with not more than a stoichiometric amount of at least one difunctional chain extending reagent to a viscosity endpoint corresponding to a molecular weight in the range from about 20,000 to about 200,000 at a residual free isocyanate content not exceeding 0.5 percent by weight based on weight of said polyurethane, and terminating such reaction; contacting said elastomer and said substrate; and maintaining such contact at a temperature and pressure and for a time sufficient to effect curing of said thermoplastic polyurethane adhesive system.