Abstract: A method for flexibilizing an epoxy resin is disclosed which comprises (a) preparing a dicarboxy-terminated prepolymer by reacting a carboxylic anhydride with a polybutadiene having a minor amount of pendant vinyl groups at a temperature from about 125.degree. to about 140.degree. F.; (b) reacting the prepolymer with an excess of liquid epoxy resin at a temperature from about 180.degree. to about 200.degree. F.; (c) adding a vinyl monomer in an amount of about 2% to about 25% of the mixture; and (d) adding epoxy and vinyl polymerization catalysts to cure the mixture.

Abstract: Polyurethane resins are prepared by reacting a high solids polyol-containing component with an isocyanate-containing component. The polyol-containing component comprises the transesterification product of from about 70 to about 90 parts by weight castor oil and from about 5 to about 20 parts by weight pentaerythritol, where the solids content of the polyol-containing component is at least about 60% by weight. Preferably, the polyol-containing component also comprises from about 5 to about 30 parts by weight of a condensation agent having a molecular weight of less than about 400 and selected from the group consisting of polycarboxylic acids having up to about 4 carboxyl groups, methyl and ethyl esters of such polycarboxylic acids, and combinations thereof.