Synthesis and characterization of polyurethane coatings based on soybean oil–polyester polyols

Soybean oil was esterified by glycerol (1:3) molar ratio to produce monoglycerides, and then reacted with phthalic anhydride at ratios 20%, 40% and 60% to produce polyester polyols denoted by PES20, PES40 and PES60. They were investigated by IR spectra and solubility in methanol. Diphenylmethane diisocyanate was reacted with these polyols at NCO/OH ratios 1.2, 1.4, 1.6 using toluene as a solvent to produce polyester–polyurethane coatings, which were characterized by IR spectra. The prepared coatings were characterized by flexibility, pencil hardness, impact resistance and chemical resistance. Good properties of the prepared coatings increase in the direction of increasing hard segments in the sample.