Polyester resin compositions and methods

Claim 1

IN THE PREPARATION OF THERMOPLASTIC POLYESTERS FROM DISCARBOXYL ACID ANHYDRIDES AND MONOEPOXIDES, THE PROCESS FOR PREPARING BRANCH CHAIN POLYESTERS HAVING END GROUPS WHICH DO NOT REACT WITH EACH OTHER DURING THE PREPARATION COMPRISING A MONOMERIC POLYHYDROXY ALCOHOL WHICH ACTS AS A REACTION INITIATOR AND IS REACTIVE PRIMARILY WITH THE ANHYDRIDE RATHER THAN THE MONOEPOXIDE, SAID ALCOHOL SELECTED FROM AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF ERYTHRITOL, DIPENTAERYTHRITOL AND TRIPENTAERYTHRITOL EACH HAVING AT LEAST THREE HYDROXYL RADICAL SUBSTITUENTS, THE NUMBER OF SUBSTITUTENTS BEING EQUAL TO THE NUMBER OF BRANCH CHAINS DESIRED, REACTING THE INITIATOR, THE ANHYDRIDE AND THE MONOEPOXIDE BY HEATING ALL OF THE REACTANTS AT AN ELEVATED TEMPERATURE BELOW 150*C. SUFFICIENT TO BRING ABOUT A REACTION OF ANHYDRIDE WITH SUBSTITUENTS OF THE INITIATOR FORMING CARBOXYL GROUPS, AS WELL AS A REACTION OF MONOEPOXIDE WITH THE CABOXYL GROUPS, THUS PROVIDING HYDROXYL GROUPS FOR REACTION WITH THE ANHYDRIDE, AND MAINTAINING THE TEMPERATURE BELOW THAT AT WHICH A CARBOXYL-HYDROXY REACTION TAKES PLACE SO THAT END GROUPS OF POLYESTER CHAINS GROWING BY SUCCESSIVE ADDITION OF ANHYDRIDE AND MONOEPOXIDE TO THE INITIATOR DO NOT REACT WITH EACH OTHER AND FORM WATER, SAID MONOEPOXIDE BEING FREE OF SUBSTITUENTS CAPABLE OF REACTING WITH AN ACID ANHYDRIDE.