Improved Operating Scenarios for the Production of Acrylonitriie-Butadiene Emulsions

摘要

This article focuses on important aspects related to the production of acrylonitrile-butadiene rubber (nitrile rubber or NBR) emulsions using a train of eight continuously stirred tank reactors. The first aspect we discuss concerns miscellaneous operating procedures, targeted toward achieving desired properties of the NBR emulsion and at the same time reducing the amount of off-spec material during the transient period. In one of the operating procedures discussed, the first reactor is started full of 'batch recipe,' whereas the remaining reactors in the train are half full with all reaction ingredients. In another case, we discuss an alternative design scenario, where the first reactor in the train is of a much smaller volume compared with the following reactors. The benefits of these two operating (production) scenarios are illustrated by comparison of different polymer and latex properties obtained with the commonly used procedures. Second, we discuss a novel criterion that can quantitatively distinguish between Cases I and II kinetics emulsion polymerization behavior with respect to continuous reactor stability (oscillatory behavior). Finally, additional feed policies are addressed, such as splitting the more reactive monomer and/or other reaction ingredients among the reactors of the train for better control of certain desired properties.