Polyester binder material for coating composition

A polymer for use in multiple applications that utilizes a polymerization and transesterification route with raw materials preferably of bio-based and/or renewable origin. The polymer includes an aliphatic diacid or reactive equivalent thereof, one or more diols, and a polyalkylene terephthalate or polyalkylene napthenate which are heated under conditions of melt processing at a sufficient temperature and pressure whereby transesterification and polymerization occurs. Also provided is an admixing process that includes an end-capping or chain stopping molecule, which is added to the reaction mixture before the polymerization is complete. Additionally provided is a polymer prepared according to an admixing process that incorporates natural proteins (e.g., isolated soy proteins), carbohydrates (e.g., starch, cellulose and their derivatives), soya fatty acids, or soy meal under conditions whereby transesterification and/or transamidation occurs. The polymer may be further combined with an additional polymer selected from the group consisting of acrylics, rosins, polyesters, alkyds, and polyurethanes.