Recirculating a portion of high internal phase emulsions prepared in a continuous process

摘要

An improvement in a continuous process for making high internal phase emulsions that are typically polymerized to provide microporous, open-celled polymeric foam materials capable of absorbing aqueous fluids, especially aqueous body fluids such as urine. The improvement involves recirculating a portion (about 50% or less) of the emulsion withdrawn from the dynamic mixing zone of this continuous process. This increases the uniformity of the emulsion ultimately obtained from this continuous process in terms of having the water droplets homogeneously dispersed in the oil phase. This also improves the stability of the HIPE and expands the temperature range for pouring and curing this HIPE during subsequent emulsion polymerization. The improvement also eliminates the need for a static mixer outside the dynamic mixing zone, and allows for processing where relatively low pressure drops are required across the mixing zone.