Polyester amides from linseed oil for protective coatings

Abstract

Abstract The sodium alkoxide‐catalyzed reaction of linseed oil or linseed methyl esters with diethanolamine produces almost exclusively linseed diethanolamides. Reaction conditions, e.g., temperature, amount of excess diethanolamine and mode of adding reactants, are reported. The best conditions for producing diethanolamide directly from linseed oil (1 mole) required adding oil to the sodium alkoxide in diethanolamine (6 moles) and heating at 110舑115C for 35 min. The linseed diethanolamide isolated in 93舑95% yield was an amber oil. Progress of the reaction, followed by thin‐layer chromatography, showed only trace amounts of byproducts. Polyester amides were prepared by heating linseed diethanolamide in refluxing xylene with dibasic acids or anhydrides, e.g., azelaic, maleic, fumaric, phthalic, terephthalic, itaconic, brassylic and dimer acids. Molecular weight, viscosity and film properties (air‐dried and baked) of the polyester amides were determined.