Conserving dihydric alcohol in the preparation of polyesters

Claim 1

A METHOD OF FORMING A POLYESTER OF A DIHYDRIC ALCOHOL COMPONENT AND A DICARBOXYLIC ACID COMPONENT, EACH CONSISTING SOLELY OF ATOMS OF CARBON, HYDROGEN AND OXYGEN, THE DIHYDRIC ALCOHOL COMPONENT CONTAINING ABOUT 2 TO 10 CARBON ATOMS PER MOLECULE AND BOILING IN A RANGE BELOW ABOUT 280*C., THE DICARBOXYLIC ACID COMPONENT BEING FREE OF PLURAL CARBON TO CARBON BONDS OTHER THAN BENZENOID DOUBLE BONDS, WHICH METHOD COMPRISES HEATING AN ESTERIFICATION MIXTURE OF SAID ALCOHOL AND SAID ACID IN A NONREACTIVE LIQUID AROMATIC HYDROCARBON SOLVENT FOR THE MIXTURE, SAID SOLVENT BEING ADAPTED TO FORM A CONSTANT BOILING MIXTURE WITH WATER AND NOT FORMING TERNARY VAPOR MIXTURES WITH WATER AND SAID ALCOHOL, AND BEING SUBSTANTIALLY IMMISCIBLE WITH WATER, HEATING OF THE ESTERIFICATION MIXTURE BEING AT A TEMPERATURE TO EFFECT ESTERIFICATION AND TO EVOLVE WATER OF ESTERIFICATION, BUT ABOVE THAT OF BOILING OF THE SOLVENT AND BELOW 536*F., PASSING THE VAPORS FROM THE REACTION UPWARDLY THROUGH A VAPOR ZONE AT A TEMPERATURE ABOVE ABOUT 212*F. AND BELOW THE TEMPERATURE OF HEATING OF THE MIXTURE, ADDING COOLING WATER TO THE TOP OF THE ZONE TO STRIP OUT VAPORS OF DIHYDRIC ALCOHOL THEREFROM, THE TOP OF THE ZONE BEING MAINTAINED AT A TEMPERATURE ABOVE THAT OF BOILING OF THE MIXTURE OF WATER AND SOLVENT AND BETWEEN ABOVE 157*F. AND ABOUT 210*F., AND DRAWING THEREFROM A MIXTURE OF VAPORS FROM SAID SOLVENT AND WATER IN SUBSTANTIALLY CONSTANT BOILING RATIO, HEATING OF THE ESTERIFICATION MIXTURE BEING CONTINUED UNTIL A POLYESTER HAVING A HYDROXYL VALUE IN A RANGE BETWEEN 50 AND ABOUT 500 IS OBTAINED.

Claim 2

A METHOD OF FORMING A POLYESTER OF A DIHYDRIC ALCOHOL COMPONENT AND A DICARBOXYLIC ACID COMPONENT, EACH CONSISTING SOLELY OF ATOMS OF CARBON, HYDROGEN AND OXYGEN, THE DIHYDRIC ALCOHOL COMPONENT CONTAINING ABOUT 2 TO 10 CARBON ATOMS PER MOLECULE AND BOILING IN A RANGE BELOW ABOUT 280*C., THE DICARBOXYLIC ACID COMPONENT BEING FREE OF PLURAL CARBON TO CARBON BONDS OTHER THAN BENZENOID DOUBLE BONDS, WHICH METHOD COMPRISES HEATING AN ESTERIFICATION MIXTURE OF SAID ALCOHOL AND SAID ACID IN A NONREACTIVE LIQUID AROMATIC HYDROCARBON SOLVENT FOR THE MIXTURE, SAID SOLVENT BEING ADAPTED TO FORM A CONSTANT BOILING MIXTURE WITH WATER AND NOT FORMING TERNARY VAPOR MIXTURES WITH WATER AND SAID ALCOHOL, AND BEING SUBSTANTIALLY IMMISCIBLE WITH WATER, HEATING OF THE ESTERIFICATION MIXTURE BEING AT A TEMPERATURE TO EFFECT ESTERIFICATION AND TO EVOLVE WATER OF ESTERIFICATION, BUT ABOVE THAT OF BOILING OF THE SOLVENT AND BELOW 536*F., PASSING THE VAPORS FROM THE REACTION UPWARDLY THROUGH A VAPOR ZONE AT A TEMPERATURE ABOVE ABOUT 212*F. AND BELOW THE TEMPERATURE OF HEATING OF THE MIXTURE, ADDING COOLING WATER TO THE TOP OF THE ZONE TO STRIP OUT VAPORS OF DIHYDRIC ALCOHOL THEREFROM, THE TOP OF THE ZONE BEING MAINTAINED AT A TEMPERATURE ABOVE THAT OF BOILING OF THE MIXTURE OF WATER AND SOLVENT AND BETWEEN ABOVE 157*F. AND ABOUT 210*F., AND DRAWING THEREFROM A MIXTURE OF VAPORS FROM SAID SOLVENT AND WATER IN SUBSTANTIALLY CONSTANT BOILING RATIO, HEATING OF THE ESTERIFICATION MIXTURE BEING CONTINUED UNTIL A POLYESTER HAVING A HYDROXYL VALUE IN A RANGE BETWEEN 50 AND ABOUT 500 IS OBTAINED.