Process for the preparation of high molecular weight polymerizable orthophthalate polyesters

Claim 1

A PROCESS FOR THE PREPARATION OF AN IMPROVED ESSENTIALLY LINEAR POLYESTER RESIN CONTAINING ETHYLENIC UNSATURATION WHICH COMPRISES: (1) HEATING A REACTION MIXTURE COMPRISING A SATURATED DIHYDRIC ALCOHOL ANN A,B-ETHYLENICALLY UNSATURATED DICARBOXYLIC ACID AND FROM ABOUT 10 TO 90 MOL PERCENT, BASED ON THE TOTAL MOLS OF POLYCARBOXYLIC ACID PRESENT IN SAID REACTION MIXTURE, OF ORTHO PHTHALIC ACID, AT A TEMPERATURE OF FROM ABOUT 160*C. TO 225*C. UNTIL THE SOFTENING POINT OF THE RESULTING ESTERIFIED MIXTURE REACHES A SUBSTANTIALLY MAXIMUM VALUE AS DETERMINED BY THE DENNIS MELTING POINT BAR METHOD AND THHE ACID NUMBER OF SAID MIXTURE IS WITHIN THE RANGE OF FROM ABOUT 20 TO 50, SAID MIXTURE BEING FREE OF ESTERIFICATION CATALYST, (2) FORMING A SECOND REACTION MIXTUURE CIMPRISING (A) THE ESTERIFIED MIXTURE OF STEP (1) AND (B) FROM ABOUT 0.005% TO 0.5% BY WEIGHT, BASED ON THE WEIGHT OF SAID ESTERIFIED MIXTURE, OF A BASIC ESTERIFCATION CATALYST, SAID SECOND REACTION MIXTURE BEING FREE OF CCRO LINKING MONOMERS CONTAINING THE CH2=C< GROUP, AND (3) HEATING SAID SECOND REACTION MIXTURE AT A TEMPERATURE OF FROM ABOUT 150*C. TO 210*C. UNDER VACUUM UNTIL A SOLUBLE FUSIBLE PRODUCT HHAVING A SOFTENING POINT AT LEAST ABOUT 10*C. GREATER THAN THAT OF THE ESTERIFIED MIXTURE OF STEP (1) IS OBTAINED.