2-PACKAGE POLYURETHANE COATINGS BASED ON CASTOR OIL-MODIFIED POLYESTERAMIDES FOR INDUSTRIAL MAINTENANCE COATINGS

Hydroxy-terminated polyesteramides (HTPEAs) derived from castor oil (R icinus communis) have been employed as hydroxy components of two-packa ge urethane (ASTM-V type) composition. N,N-bis (2-hydroxyethyl) castor amide (HECA) has been prepared by aminolysis of castor oil with dietha nolamine using zinc oxide as the catalyst. HECA on reaction with two d ifferent dibasic acids, viz. phthalic anhydride and isophthalic acid i n varying molar ratios gave a series of hydroxy-terminated polyesteram ide (HTPEA). Coating compositions were prepared from the resins by ble nding them with aromatic isocyanate-terminated prepolymer derived from tolylene diisocyanate (TDI). The ambient temperature-cured film prope rties of these compositions have been evaluated. The urethane composit ions prepared for the study could be used for industrial maintenance c oatings. Further, coatings based on HTPEAs derived from isophthalic ac id are found to be as good as in many properties to their phthalic anh ydride counterparts.