One-step vinyl chloride (co)polymerisation in aq. dispersion - using redox catalyst system contg. monomer-soluble component added before water-soluble component

摘要

In an intermittent process for vinyl chloride (co)polymerisation with up to 30 wt. % copolymerisable monomer, a dispersion of water, tenside, a fatty alcohol, total quantity of monomer-soluble catalyst/s and opt. of 10 ppm (w.r.t. monomer/s) of a heavy metal salt is prepd. first, with stirring at temps. which are opt. above the chosen polymerisation temp. Vinyl chloride, or its mixt. with comonomers, is added, with stirring, to this dispersion, and the polymerisation temp. in mixt. is adjusted if necessary. Polymerisation is started on adding the water-soluble catalyst/s and is kept up to desired conversion, opt. by controlling water-soluble catalyst addn. The lattices obtd. can contain up to 50% solids, and are used for the prepn. of plastisols having a lower viscosity, esp. at high shear, than that of paste prepd. by using water-soluble initiators. Coagulate formation in latex is small. Suspension PVC proportion in latex can be increased to 50 (80)% and emulsion PVC can be set to 50 (20)%.