Chemoenzymatic synthesis and characterization of urethane oils for surface coatings

Two-step chemoenzymatic synthesis of urethane oils has been studied. Initially, the partial esters were prepared by lipase-catalyzed transesterification of soybean and linseed oils with n-butanol. Partial esters were further reacted with different diisocyanates to obtain urethane oils. The composition of the partial esters was varied with reaction time in the transesterification step. Among all the lipases, the lipozyme was found to be the most suitable lipase for the transesterification reaction, yielding 80-85%. All of the urethane oils were of low molecular weights irrespective of the type of oil used in their preparation. Urethane oils, based on MDI, exhibited the best scratch resistance. All of the urethane oils showed good acid and alkali resistance and excellent solvent resistance. These oils also satisfactorily passed the impact resistance and the flexibility tests.