REACTOR DESIGN CONSIDERATIONS FOR GAS-LIQUID EMULSION POLYMERIZATIONS- THE ETHYLENE-VINYL ACETATE EXAMPLE

Gas-liquid emulsion polymerization presents certain problems which are not normally encountered during conventional emulsion polymerizations . The existence of a comonomer in the gas phase results in mass transf er limitations under cetain reaction conditions. Designed experiments have been used to study the ethylene-vinyl acetate emulsion process. T hese studies have identified the reaction conditions under which ethyl ene mass transfer limitations prevail. The present paper will focus on the results of a more detailed study of the reactor design itself. Th ese results may be used to eliminate or reduce mass transfer limitatio ns during ethylene-vinyl acetate emulsion polymerization. Results show ing the effects of impeller design, sparging and agitation on the rate of polymerization, cumulative copolymer composition, particle size an d number, and gel content are presented. As a result, one can identify the requirements, with respect to both reaction kinetics and reactor design, for the production of a high solids, homogeneous, high ethylen e content copolymer. These observations, when coupled with the approac h and the kinetic results presented earlier, provide a check-list of t he requirements for successful scale-up of the process.