Polymerisationsverfahren für Acrylate.

摘要

The continuous solution polymerization of an acrylate, particularly methyl methacrylate, is practiced in the presence of a large quantity of solvent by introducing the monomer feed into a continuous loop of recycled solvent and removing the polymerized product therefrom. The polymerization is practiced in a plurality of stages, preferably two stages wherein the bulk of the polymerization is performed in the first stage and the final stage is operated to deplete the initiator and any other polymerization modifiers, thereby forming a crude polymerizate for devolatilization. A product of superior thermal stability and optimum heat distortion temperature is achieved by the addition of some of the comonomer such as methyl acrylate, or ethyl acrylate, etc., to the final stage or stages of the polymerization. Additionally, the product quality is enhanced by addition of a portion of the chain transfer agent, such as n-dodecyl mercaptan, to the final stage or stages of polymerization. The crude polymerizate is preheated and devolatilized in a flash zone. Sufficient pressure is maintained on the crude polymerizate in the devolatilizer preheater to avoid the formation of foam encrustations on the heat exchange surfaces of the devolatilizer preheater and on the surfaces of the transfer lines.