| 摘要 |
1,199,261. Evaporators, film type. SHELL INTERNATIONALE RESEARCH MAATSCHAPPJJ N.V. 14 Jan., 1969 [16 Jan., 1968], No. 2203/69. Heading B1B. Volatile components, such as monomer or solvents, are removed by vaporization from a molten polymer by feeding it through annular ring 3 into a barrel I wherein the polymer is distributed as a moving film on the inner surface iby a rotating, hollow worm-screw 2 having a helical flight 4 with a clearance of 0.5 to 2.8 m.m. from the inner surface of the barrel. The screw has slots (not shown) through which the vapours pass into the hollow core, which is connected to a source of vacuum. The screw is rotated at high speed so that the polymer is subjected to a rate of shear 'between 500 and 2000 reciprocal seconds. The devolatilized polymer is forced through pumping section C to exit 6. The barrel may be surrounded by a heating or a cooling jacket. The worm screw may have a plurality of flights. Short strips having varying clearances may be mounted on the screw parallel to the flights. |
