Thermally stabilized segmented copolyester adhesive

A thermally stabilized thermoplastic hot melt adhesive composition in the molten state which comprises, based on the total thermoplastic components, (A) 1 to 99 percent by weight of thermoplastic segmented copolyester consisting essentially of a multiplicity of recurring short chain ester units and long chain ester units joined through ester linkages, said short chain ester units amounting to 15 to 75 percent by weight of said copolyester and being of the formula ##STR14## and said long chain ester units amounting to 25 to 85 percent by weight of said copolyester and being of the formula ##STR15## wherein R is the divalent radical remaining after removal of the carboxyl groups from a dicarboxylic acid having a molecular weight of less than 350, D is the divalent radical remaining after removal of the hydroxyl groups from organic diol having a molecular weight of less than 250, and G is the divalent radical remaining after removal of the terminal hydroxyl groups from long chain glycol having an average molecular weight of 350 to 6000, said copolyester having a melt index of less than 150, a melting point of at least 90.degree. C., an inherent viscosity in the range of 1.0 to 1.7, and an acid number of less than 3;

• (B) 1 to 99 percent by weight of low molecular weight thermoplastic resin which forms compatible mixtures with the segmented copolyester, is thermally stable at 150.degree. C., and has a melt viscosity of less than 10,000 centipoises at 200.degree. C.;
• stabilized against substantial loss in viscosity in said molten state with (C) 0.1 to 4.0 percent by weight, based on the weight of copolyester and resin, of an alkaline earth oxide.

Method of preparing a thermoplastic composition which comprises blending in molten form, based on the total thermoplastic components,

• A. 1 to 99 percent by weight of thermoplastic segmented copolyester consisting essentially of a multiplicity of recurring short chain ester units and long chain ester units joined through ester linkages, said short chain ester units amounting to 15 to 75 percent by weight of said copolyester and being of the formula:
• ##STR18## and said long chain ester units amounting to 25 to 85 percent by weight of said copolyester and being of the formula:
• ##STR19## wherein R is the divalent radical remaining after removal of the carboxyl groups from dicarboxylic acid having a molecular weight of less than 350, D is the divalent radical remaining after removal of the hydroxyl groups from organic diol having a molecular weight of less than 250, and G is the divalent radical remaining after removal of the terminal hydroxyl groups from long chain glycol having an average molecular weight of 350 to 6000, said copolyester having a melt index of less than 150, a melting point of at least 90.degree. C., an inherent viscosity in the range of 1.0 to 1.7, and an acid number not greater than 3.0;
• B. 1 to 99 percent by weight of low molecular weight thermoplastic resin which forms compatible mixtures with the segmented copolyester, is thermally stable at 150.degree. C., and has a melt viscosity of less than 10,000 centipoises at 200.degree. C.;
• stabilized against substantial loss of viscosity in said molten form with
• C. 0.1 to 4.0 percent by weight, based on the weight of copolyester and resin, of an alkaline earth oxide.