A process for the preparation of low-viscosity copolymers - latices having a high solids content

摘要

High solids, low viscosity copolymer latices, especially useful when formulated as surface coatings, are prepared from (a) at least one vinyl ester monomer in an amount representing from about 50 weight percent to about 95 weight percent of total monomer charge and (b) at least one acrylate ester and/or methacrylate ester monomer representing the balance of the total monomer charge. The latices are prepared in a multi-stage polymerization sequence in which a significant portion of the total vinyl ester monomer charge is polymerized together with from 0 to about 50 weight percent of the total acrylate ester and/or methacrylate ester monomer in the initial stage in an aqueous emulsion reaction medium containing a suitable catalyst and thereafter, the remaining portion of the total vinyl ester monomer charge together with the remaining portion of the acrylate ester and/or methacrylate ester monomer charge is polymerized in the reaction medium containing additional catalyst if needed and polymerization is continued substantially to completion. The examples are directed towards copolymers of butyl acrylate with vinyl acetate.