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.
丙烯酸酯(尤其是
甲基丙烯酸甲酯)的连续溶液聚合是在存在大量溶剂的情况下进行的,方法是将单体进料引入循环溶剂的连续循环中,并从其中取出聚合产物。聚合反应分多个阶段进行,最好是两个阶段,其中大部分聚合反应在第一阶段进行,最后一个阶段用于耗尽
引发剂和任何其他聚合改性剂,从而形成用于脱溶剂的粗聚合物。在聚合的最后阶段加入一些共聚单体,如
丙烯酸甲酯或
丙烯酸乙酯等,可获得热稳定性极佳、热变形温度最佳的产品。此外,在聚合的最后阶段加入部分链转移剂,如正
十二烷基
硫醇,可提高产品质量。粗聚合物在闪蒸区进行预热和脱溶剂。在脱溶剂预热器中对粗聚合物保持足够的压力,以避免在脱溶剂预热器的热交换表面和传输线表面形成泡沫结壳。