Polyesteramides from linseed and soybean oils for protective coatings: Diisocyanate‐modified polymers

New polymeric coating materials have been prepared by a triethylenediamine‐catalyzed reaction of hydroxyl‐terminated polyesteramides (HTPA) from soybean or linseed oils with diisocyanates. Eight dibasic acids or anhydrides were reacted with excess N,N‐bis(2‐hydroxyethyl) fatty amide to yield HTPA; those containing 10 mole per cent excess gave isocyanate‐modified polymers with best overall film properties. Reactivity of four diisocyanates with a linseed‐HTPA was measured by disappearance of the isocyanate band in the infrared. Depending on chemical composition, structure and curing conditions, films prepared from these polymers have a wide range of drying characteristics, hardness and chemical resistance. Drying times of linseed HTPA‐urethane polymer films varied from 0.3 to 48 hr, hardness values (Sward) were from 4 to 70, alkali resistance ranged from 2 to 126 min and the hydrochloric acid and xylene resistances were good to excellent. Impact resistance exceeded 160 in.‐lb for all films except two. The soybean‐derived polymer films likewise exhibited a wide range of properties; they chiefly differed from linseed‐derived films in having greater flexibility and improved alkali resistance.