Bonding with polyisocyanates

A method of bonding (1) a segmented thermoplastic copolyester composition consisting essentially of a multiplicity of recurring long chain ester units and short chain ester units joined head-to-tail through ester linkages, said long chain ester units being represented by the formula ##EQU4## and said short chain units being represented by the formula ##EQU5## where G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly(alkylene oxide) glycol having a molecular weight of about 400-6000 and a carbon to oxygen ratio of about 2.0-4.3;

• R is a divalent radical remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight less than about 300 and D is a divalent radical remaining after removal of hydroxyl groups from a diol having a molecular weight less than about 250;
• provided said short chain ester units amount to about 15-95 percent by weight of said copolyester, and at least about 50% of said short chain ester units are identical and (2) a substrate selected from the group consisting of fiber-forming condensation polymers or regenerated cellulose which comprises applying to either said copolyester or said substrate a polyisocyanate reaction product having an available isocyanato group content of at least 2 percent and being obtained by reacting an excess of a polyisocyanate with a liquid polyol or a polyamine having an equivalent weight of about 30-2000 and then contacting said copolyester and said substrate in the presence of either elevated pressure and/or temperature.