US 4,902,773 A · Method of preparation of unsaturated polyester resins from maleic acid/anhydride

Abstract

The invention relates to the acceleration of the synthesis of unsaturated polyesters containing maleic acid/anhydride, 1 to 30 percent, preferably 5 to 15 percent of the prescribed maleic acid/anhydride is introduced into the reaction mixture in total or in two or more increments at the stage of the reaction when the acid number or the molecular weight of the mixture has reached about 50 to 250 or about 300 to 1500, respectively. Thus, the rate of polyesterification can be increased considerably, occasionally two-folds and, in addition, polyester resins of very low acid number or high molecular weight can be prepared.

Claims13

Dependent claims

A polycondensation method for preparing an unsaturated polyester comprising:

polycondensing in a reaction system maleic acid/anhydride and a saturated dicarboxylic acid with an equivalent amount or 1 to 5 mole percent of a stoichiometric excess of a diol,
said polycondensation method characterized in that additional maleic acid/anhydride in an amount of 1 to 30 percent, based on the amount of maleic acid/anhydride prescribed prior to the polycondensing step, is added to said reaction system at the stage of polycondensation when the acid number is 50 to 250 or the molecular weight of the polycondensed product formed is 300 to 1500, said additional amount of the maleic acid/anhydride is added in total or in two or more increments.

Dependencies are inferred from the claim text.

Method of preparation of unsaturated polyester resins from maleic acid/anhydride

Life of this patent

Method of preparation of unsaturated polyester resins from maleic acid/anhydride

Life of this patent

Abstract

Claims13