Continuous prodn. of particulate PVC - by feeding monomer and particulate seeding agent through reaction zone with stepwise advancement of growing particles

摘要

Continuous prodn. of vinyl chloride (co)polymers comprises gas phase polymerisation of the monomer in at least one polymerisation zone in the presence of a seeding agent (I) and a polymerisation initiator, by simultaneously and continuously introducing the monomer and particles of the (I) into the reaction zone and maintaining the polymerisation temp. of the mixt. in the zone whilst continuously removing polymer from the zone. During the growth of the (co)polymer particles they are maintained in the form of a thin layer and move down the reaction zone in small successive leaps such that at the outlet from the zone the (co)polymer particles have had virtually the same residence time in the reaction zone. Process gives polymer with improved homogeneity and degassing properties.