Polybutadiene latex with high solids content and increased particle size

摘要

A polybutadiene latex (I) is prepared by: (a) preparation of an emulsion polymerisation medium (II) by mixing water, butadiene monomers, surfactants, chain transfer reagent, initiator and electrolyte at 60-80 deg C for 8-16 hours to achieve 80-100% conversion; and (b) agglomeration of (I) at 5-20 deg C higher than the polymerisation temperature for 4-12 hours by addition of a surfactant and an agglomerisation agent (III). Also claimed are: (i) a process for the preparation of (III) by a three-stage process involving: (1) discontinuous polymerisation of a 1-12C alkyl acrylate, an anionic surfactant and an anionic initiator to form a nucleus of an agglomeration agent; (2) addition of a 1-12C alkyl arylate and an ionic comonomer to the polymer product from stage (1); and (3) further addition of 1-12C alkyl acrylate, an ionic comonomer and an anionic initiator to the polymer product from stage (2), to cause copolymerisation at the surface of the agglomeration agent nucleus; (ii) the latex (I) and the agglomeration agent (III).