Preparation of dehydrated castor-oil acid modified epoxy UV-curable cathodic electrophoretic coating

The epoxy resin was modified by esterification with dehydrated castor oil and then reacted with diethanolamine.The UV curing cathodic electrodeposition coating was prepared from the above product under the action of photoinitiators and reactive monomer.The epoxy molecular weight,type and amount of catalyst,reaction temperature on the esterification reaction were investigated.The effects of esterification degree,amine ring-opening rate,type and amount of reactive monomer on the coating stability and coating performance were also studied.The results showed that the UV-curable cathodic electrophoretic paint could cure fastly and completely and had uniform,plump and bright surface,good adhesion and excellent solvent resistance under the preparaton conditions as followed:using epoxy E-44,reaction temperature 110 ℃,catalyst N,N-dimethyl benzylamine,mass fraction 0.8%～1%,esterification degree 35%～40%,amine ring opening rate ≥ 60%,mass fraction of reactive monomer pentaerythritol triacrylate 15%～20%.