Process for preparing non vitrified homopolymers of methyl methacrylate having low residual monomer contents

摘要

The prodn. of unvitrified methyl methacrylate (MMA) homo- or co-polymers with a low residual monomer content (I) comprises: (a) prepn. of a dispersion of an emulsion polymer of MMA and opt. up to 50 wt.% comonomer (II); (b) reducing the residual monomer content by adding more polymerisation initiator and heating; and (c) spray drying at a temp. above the b.pt. of MMA or above that of any comonomer present with a higher b.pt. than MMA. Also claimed is unvitrified spray-dried PMMA emulsion polymer (I) contg. less than 5 wt.% comonomer, with a residual monomer content of not more than 50 (pref. not more than 30) ppm as obtd. by this process.