| abstract |
Olefinically unsaturated compounds which are practically insoluble or only partly soluble in water are polymerized to stable polymer dispersions in an aqueous phase in the presence of emulsifiers and of catalysts or catalyst systems which yield radicals in the aqueous phase by a process characterized by a flow of drops of the compound or compounds to be polymerized through the aqueous phase, the movement of the monomer drops with regard to the aqueous phase being caused mainly by the difference in the specific gravity of the two phases. Preferably the monomer is p allowed to separate as a layer distinct from the aqueous phase after its passage through this phase, the monomer being withdrawn from this separated layer and again passed through the aqueous phase, or a separate aqueous phase. The aqueous phase may contain some preformed polymer when the process is initiated, and fresh water phase may be fed to the reaction space and the polymer dispersion drained off, feed and drain preferably being balanced. The Specification describes the preparation of polyvinylidene chloride, polyvinyl chloride, polybutadiene and of copolymers of vinylidene chloride with methyl methacrylate, methacrylonitrile, vinyl acetate or vinyl chloride, and of butadiene and styrene, and the process is also applicable to the preparation of polyethylene and of copolymers of butadiene and acrylonitrile. Ingredients of the aqueous phase specified are potassium and ammonium persulphates, sodium sulphite, sodium mersolate, potassium oleate, sodium bicarbonate and tertiary dodecyl mercaptan. |