PRODUCTION OF VESICULATED POLYMER BEADS

摘要

Vesiculated polymer beads containing a pigment have in the past been produced employing a process using a polyamine base but this has introduced yellowing of the beads and avoidance of its use is desirable. Accordingly a process has been developed which produces vesiculated polymer beads which have a reduced tendency to be yellow. The new process involves forming an oil phase of the polyester resin containing the pigment which is mixed with a first aqueous phase containing a particular base to form an emulsion to which a second aqueous phase containing an emulsifying agent is then mixed. The dispersion of globules so formed is polymerised by the action of a polymerisation initiator. Preferably the pigment is titanium dioxide pigment.