| 摘要 |
Prepn. of polymer dispersions by emulsion or suspension polymerisation of a monomer or monomers in aq. medium, removal of deposits, sepn. and condensn. of gaseous prods. The opt. heated suspension is sprayed in the form of a hollow cone or disc of droplets of at most 6 mm dia. into an upright, pref. cylindrical tank, so as to fall on the vertical walls. The prod. is sepd. and collected in the lower part of the tank and gaseous materials above the spray orifice as in DT 2435704. In this addn., the dispersion is successively sprayed into >=2 consecutive tanks, being passed from the base of one to the spray unit of the next. The gaseous by-prods., opt. with admixt. of inert gas are passed in the opposite direction (counter-current). The process is used in the mfr. of PVC and copolymers. Removal of monomer traces is more efficient than by the single tank process of the main patent. Passage of PVC dispersion at 70 degrees C and 250 Torr press. through 3 tanks with residence time 3x4 = 12 min. gave a residual monomer content of 0.009 wt.% compared with 0.06 wt.% when 1 tank with 12 min. residence time was used. (Initial monomer content - 0.8 wt.%).
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