Process for preparing copolymers, and products fully or partly made of these copolymers.

摘要

In a process for preparing coplymers by polymerization in aqueous dispersion of styrene and/or alpha -methyl styrene with acrylonitrile and/or methacrylonitrile with the aid of a compound yielding free water-soluble radicals, a compound yielding water-soluble radicals is added in a quantity of 0.05 to 2.5 parts per 100 parts of monomer added after the conversion has become larger than 75%, the monomer addition has been terminate, the rate of conversion has become smaller than 15% per hour and when at least 0.1 w.-% of non-converted (meth) acrylonitrile in relation to the reaction medium has remained therein.
<??>The copolymers obtained by this process have a high heat distortion temperature and a low free-monomer content. The invention is aimed in particular at the manufacture of copolymers of styrene and acrylonitrile (SAN), alpha -methyl styrene and acrylonitrile ( alpha -methyl-SAN) and graft polymers thereof on a rubber (ABS). Products made or partially made of these copolymers.