In the process of preparing electrophoretic ink microcapsules by in-situ polymerization

oligomers instead of traditional prepolymers (hydmxymethyl urea and dihydmxymethyl Hrea) of urea

formaldehyde were used as monomers of reaction

because oligomers ale more likely to be adsorbed on the surface of oil phase droplets．The general problems of in-situ polymerization such as coagulating

sticking

coarse surface

low productivity eyc．have been solved The properties of viscosity and surface activity of urea-formaldehyde oligomers were studied

as well as their relationship with the encapsulation efficiency of mierocapsules．The electmphoretic ink micmcapsules were prepared successfully by this method．