PROCESS FOR PRODUCING ISOPHTHALIC ACID-BASED UNSATURATED POLYESTER RESIN

摘要

During the 1st stage of a polycondensn. reaction for the prepn. of isophthalic acid based unsatd. polyester resin, the following cpds. are also present in addn. to isophthalic acid: 35-85 (pref. 40-70) mol.% of the total glycol concn. 0.01-2 wt.% (based on total reaction mixt.) of di:methyl or di:butyl-phthalate accelerator and opt. catalyst. The 1st polycondensn. stage proceeds at 180-230 deg. C until a 50-60 mg KOH/g acid value is reached. - During the 2nd stage when maleic=anhydride or other di:carboxylic=acid components are added together with the remainder of the total quantity of glycol, the reaction proceeds in the presence of customary catalyst at 180-230 deg. C to an acid value of 2-50 mg KOH/g. The resin is cooled to 140-190 deg. C when vinyl monomer and inhibitor are adde