Process for degassing vinyl chloride-base polymers and copolymers prepared in bulk and polymers and copolymers having an improved sieving capability resulting therefrom

摘要

A process for degassing polymers and copolymers which are prepared by bulk polymerization of a vinyl chloride-base monomer composition, in which the polymerizate is kept in an agitated condition, the monomer composition to be removed is adjusted from the polymerization pressure to an absolute pressure of less than 0.16 bar, the polymerisate is brought to or maintained at a temperature which is at least equal to 70 C. and lower than the temperature at which degradation of the polymer or copolymer begins, and said pressure and temperature conditions are maintained substantially until degassing stops. After the proportion of residual vinyl chloride monomer in the polymer or copolymer has been reduced to a value below 2000 mg/kg, the polymerizate is brought into contact with water to which at least one anionic surface active agent is added.