PRODUCTION OF MINUTE PARTICLE FORMED TO MICROCAPSULE

摘要

PURPOSE:To improve negative chargeability of the title minute particles by stirring mother particles having a specified number average particle size together at high speed with daughter particles having a specified number average particle size prepd. by polymerizing monomers for forming the daughter particles in an aq. medium contg. an anionic surface active agent. CONSTITUTION:Mother particles having 1-200mum number average particle size are prepd. On one hand, daughter particles having <=1/5 number average particle size of that of the mother particles are prepd. by polymerizing 100pts.wt. mono mer compsn. for forming the daughter particles in an aq. medium contg. 0.01-0.2 pts.wt. anionic surface active agent in the presence of 0.03-0.15pt.wt. persulfate, adding further 0.15-1.0pts.wt. persulfate when the coversion of the monomer reaches 65%. The mother particles and the daughter particles are stirred at high speed in an air stream. Thus, a covering layer consisting of the daughter particles is formed on the surface of the mother particles, and minute particles formed to microcapsules are obtd.