METHOD FOR PRODUCING POLYVINYL CHLORIDE HIGH SHOCK DENSITY BY THE SUSPENSION METHOD AND ITS USE.

摘要

1. Process for the production of polyvinyl chloride of high apparent density according to the suspension polymerization process in the presence of a free-radical initiator and a protective colloid under maximally autogeneous vinyl chloride pressure in the autoclave, at pH values of between 3 and 8, while stirring at a temperature of from 40 degrees to 70 degrees C, optionally in the presence of alkali metal salts and optionally other customary auxiliaries, such as emulsifiers, characterized in that vinyl chloride is polymerized a) in the presence of from 0.01 % to 0.3 % by weight of monomer-soluble free-radical initiator, b) in the presence of from 0.05 % to 1 % by weight of a water-soluble polyvinyl alcohol having a hydrolysis degree of from 80 to 90 mole-% and a viscosity of from 15 to 50 mPas, measured in a 4 % by weight aqueous solution at 20 degrees C with a Höppler falling-ball viscosimeter, wherein the indicated amounts are based on the weight of the monomer used, and at a peripheral speed of the stirring mechanism of not more than 7.4 m/s.