Process for producing water-soluble vinyl high-polymers by reversed-phase emulsion polymerization

摘要

An improved process for producing powdery water-soluble vinyl high- polymers by reversed-phase emulsion polymerization. The vinyl monomer is polymerized in the form of W/O type emulsion dispersed as an aqueous solution in a non-polar organic solvent immiscible with water and having a boiling point in the polymerization temperature range of the vinyl monomer, under stationary evaporation and reflux of part of the solvent, whereby the oxygen in the polymerization system is completely removed and thus the polymerization is enhanced to achieve an extremely high polymerization degree. Further, the aqueous solution of the monomer is added and dispersed in the polymerizing system stepwise or continuously at such a rate that the concentration of the polymer produced in the particles of the emulsion is maintained to a value of 20% or more to the completion of the reaction, whereby the dispersed particles are substantially completely prevented from agglomeration by virtue of the non-tackiness of the particles having a high concentration of the polymer.