| 摘要 |
<p>Granular polyoxymethylene (POM) having, in addn. to oxymethylene units, 0.1-20 wt. % oxyalkylene units of 2-8C atoms in the main chain (as in the parent patent) is prepd. from a soln. or dispersion of POM in a MeOH/H2O mixt. the temp. of which is 5 degrees-65 degrees C above the sintering temp. (Ts) of the POM. In stage 1, by mixing with a proportion of a turbulently flowing cooling agent consisting of a suspension of POM in a MeOH/H2O mixt., the material is cooled to a temp. of 0 degree-10 degrees C above Ts. In stage 2, the resulting mixt. is cooled to a temp. 1 degree-10 degrees C below Ts by mixing with the remaining portion of the same cooling agent and finally the granular POM obtd. is sepd. and dried. In this addn. stage 2 is carried out with the help of cooling equipment. Used to convert POM polymer into a form suitable for moulding. An improved prod. compared with the present standard technique is obtd. An appreciable increase of the solids content at the drying stage and a higher bulk density in the final prod. are obtd. producing energy savings in processing.</p> |
