PURPOSE: To effectively eliminate a volatile component from a styrene polymer by subjecting a polymn. soln. contg. the polymer to flash evaporation under a reduced pressure in a vacuum vessel and then introducing the soln. into a twinscrew mixer having a self-cleaning function.
CONSTITUTION: A polymn. soln. 3 contg. a styrene polymer and obtd. by soln. or bulk polymn. is heated with a heat exchanger 4 to raise the temp. and subjected to flash evaporation under a reduced pressure in one step or multistep in a vacuum vessel 1 to separate most of the volatile component from the soln. 3, and the separated volatile component is discharged through a gas exit 5. The soln. 6 is then fed through a gear pump 7 into a twin-screw mixer 2 having a self-cleaning function and pref. not having an interior dead space. The residual volatile component is separated from the soln. 6 in the mixer 2 under stirring with a stirrer blade rotating and discharged through an exhaust nozzle 8. The resulting polymer is taken out of the mixer 2 with a gear pump 9, water-cooled, and pelletized.
OMOTO SETSUO
MATSUBARA WATARU
KONDO MASAMI
