Process of preparing unsaturated polyester resins

Claim 1

THE PROCESS FOR PREPARING UNSATURATED POLYESTERS COMPRISING THE STEPS OF (1) REACTING UNDER POLYCONDENSATION CONDITIONS A REACTIVE MIXTURE CONSISTING ESSENTIALLY OF REACTANTS (A) A BENZENE DICARBOXYLIC ACID OF THE GROUP CONSISTING OF ISOPHTHALIC ACID, TEREPHTHALIC ACID, ALKYL ISOPHTHALIC ACID, ALKYL TEREPHTHALIC ACID AND MIXTURES THEREOF WHERE EACH SUBSTITUTED ACID CONTAINS 1-3 ALKYL GROUPS AND EACH ALKYL GROUP CONTAINS 1-4 CARBON ATOMS, AND (B) A FIRST DIHYDRIC ALCOHOL, HEREINAFTER DEFINED, IN AN AMOUNT SUFFICIENT TO SOLUBILIZE SAID BEZENE DICARBOXYLIC ACID, THE REACTION BEING CONTINUED UNTIL THE WATER OF ESTERIFICATION THEORETICALLY PRODUCIBLE BY THE FIRST STEP REACTANTS HAS BEEN PRODUCED AND REMOVED FROM THE REACTION ZONE, THE AMOUNT OF WATER REMOVED CORRESPONDING TO THE AMOUNT PRODUCIBLE AT THE BENZENE DICARBOXYLIC ACID SOLUBILIZATION POINT BUT NOT EXCEEDING ABOUT 90 PERCENT OF THE THEORETICALLY PRODUCIBLE AMOUNT, AND (2) REACTING UNDER POLYCONDENSATION CONDITIONS THE PRODUCT MIXTURE PRESENT IN SAID REACTION ZONE AT THE COMPLETION OF SAID FIRST STEP WITH (I) AN UNSATURATED DICARBOXYLIC ACID CONTAINING 4-8 CARBON ATOMS OF THE GROUP CONSISTING OF ALKENEDIOIC ACIDS AND ANHYDRIDES THEREOF AND (II) A SECOND DIHYDRIC ALCOHOL, HEREINAFTER DEFINED, UNTIL AN UNSATURATED POLYESTER RESIN PRODUCT HAVING AN ACID NUMBER OF NOT MORE THAN ABOUT 30 IS OBTAINED, WHEREIN THE MOLE RATIO OF BENZENE DICARBOXYLIC ACID TO UNSATURATED DICARBOXYLIC ACID CHARGED IS FROM ABOUT 9:1 TO 1:9 AND THE TOTAL AMOUNT OF SAID FIRST AND SAID SECOND DIHYDRIC ALCOHOLS CHARGED IS AT LEAST SUFFICIENT TO REACT THEORETICALLY WITH THE CARBOXYL GROUPS PRESENT IN SAID TWO ACIDS, AND WHEREIN SAID FIRST AND SAID SECOND DIHYDRIC ALCOHOLS ARE SELECTED FORM THE GROUP CONSISTING OF ALKANEDIOLS AND OXYALKANEDIOLS CONTAINING 2-9 CARBON ATOMS; SAID FIRST ALCOHOL AND SAID SECOND ALCOHOL CONTAIN A DIFFERENT NUMBER OF CARBON ATOMS; ONE OF SAID ALCOHOLS CONTAINS AT LEAST 4 CARBON ATOMS; AND SAID FIRST ALCOHOL IS THE HIGHER BOILING OF SAID FIRST AND SAID SECOND ALCOHOLS.