Gallium catalyst combinations for linear polyester making

Claim 1

AN IMPROVED PROCESS FOR PREPARING A HIGHLY POLYMERIC LINEAR POLYESER COMPRISING HATING THE FOLLOWING CONSTITUENTS UNTIL AN INHERENT VISCOSITY OF AT LEAST 0.5 IS OBTAINED AS MEASURED AT 25*C. IN A MIXTURE OF 60% OF PHENOL AND 40% OF TETRACHLORETHANE, BY WEIGHT, SAID HEATING BEING AT AN ELEVATED TEMPERATURE OF FROM ABOUT 180*C. TO ABOUT 300*C.: (1) ONE MOLE PROPORTIONOF AT LEAST ONE DIALKYL ESTER OF A DIBASIC CARBOXYLIC ACID, SAID ALKYL RADICALS CONTAINING FROM 1 TO 4 CARBON ATOMS, (2) FROM ABOUT ONE TO ABOUT 2.5 MOLE PROPORTIONS OF A GLYCOL, AND (3) FROM ABOUT 0.0001% TO ABOUT 0.1% BASED ON THE WEIGHT OF SAID LOWER DIALKYL ESTER, OF A CATALYST CONSISTING ESSENTIALLY OF (A) A COMPOUND OF A METAL CAPABLE OF CATALYZING AN ESTER INTERCHANGE BETWEEN SAID DIALKYL ESTER AND SAID GLYCOL AND WHICH IS SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM,CALCIUM, ZINC, CADMIUM, MAGANESE AND (B) A COMPOUND OF GALLIUM, THE PROPORTIONS OF (A) AND (B) BEING SUCH THAT THERE ARE FROM ABOUT 0.5 TO 75 ATOMS OF A METAL OF SAID CATALYST CONSTITUENT (A) FOR EACH ATOM OF GALLIUM.