PROCESS FOR THE PREPARATION OF AN AQUEOUS EMULSION OF VINYL CHLORIDE POLYMERS IN THE FORM OF MONODISPERSED PARTICLES OF LATEX

摘要

The invention relates to a process for preparing homo- and co-polymers of vinyl chloride in the form of a latex containing monodisperse particles, and more particularly a latex with large particles by aqueous emulsion polymerization of the monomer corresponding in one or two stages. According to the invention there is provided the first stage in the absence of surfactant and in the presence of at least 0.2% by weight relative to the (x) monomer (s), at least one initiator water-soluble selected from the group consisting of alkali metal persulfates and ammonium persulfate. the first step is carried out in the presence also of at least one water-soluble auxiliary compound, solvent of vinyl chloride in an amount such that the solubility at 25 ° C under the pressure atmosphe-America, of vinyl chloride in the aqueous phase is at least 1.5 g / l. The method allows to obtain, in a polymerization step, the vinyl chloride polymers in the form of latex containing monodisperse particles of average diameter between 0.17 and 0.8 .mu.m and, in two stages of polymerization, polymers of vinyl chloride latex form monodisperse particles of average diameter between 0.5 and 1.2 .mu.m. These latexes, they are from the first or the second stage are free of non-spherical particles.