Effects of different dicarboxylic acid on the UV-curable urethane resins made from palm fatty acid distillate

Abstract

A series of four polyol macromers with similar hydroxyl number was prepared by reacting palm fatty acid distillate with neopentaglycol, pentaerythritol, and separate equimolar amounts of isophthalic acid (IPA), terephthalic acid (TPA), phthalic anhydride (PA), and adipic acid (AA). Each macromer was then copolymerized with 2-hydroxylethyl acrylate (2-HEA) and toluene diisocyanate to produce the UV curable resins labeled as UA–IPA, UA–TPA, UA–PA, and UA–AA, respectively. The glass transition temperature (Tg), pendulum hardness, and adhesion properties of the cured films were studied. In general, all the resins produced coatings with high gloss and good adhesion. When accelerated weathering tests were carried out, films of UA–TPA could withstand UVA exposure up to 1500 h. When subjected to methyl ethyl ketone double rub test, cured films of UA–IPA and UA–TPA could withstand the highest double rubs at 90 times, followed by UA–PA and UA–AA at 45 and 15 times, respectively. Under salt spray corrosion test for 720 h, cured films showed good corrosion resistance with no observable blistering, except for UA–AA that showed slight blistering. Excellent water resistance was achieved by all cured films with good adhesion and minimal gloss reduction.