Recovery of atactic polypropylene after propylene polymerisation - by passage of soln. through heated tube

摘要

Atactic polypropylene is recovered from soln. formed as a by-product in the prepn. of a polymer contg. propylene, i.e. a propylene homopolymer, or a copolymer of propylene with another alpha-olefin. This is by vaporising the solvent in an elongated tubular heating zone, pref. at 120-300 degrees c. A press. difference of >=3, (3-50) kg/cm2 is maintained between the entry and exit, the exit speed being >=40, (40-160) m/sec. Fine molten particles of atactic polypropylene practically free of solvent are formed in suspension. These are sepd. from solvent in a sepn. zone. Method is easy to perform, allowing recovery without blocking or clogging of the evapn. appts., and without needing (BE868380) mechanical entrainment appts.