| 摘要 |
1,247,950. Partially expanded polymer particles. KOPPERS CO. Inc. 1 Oct., 1969 [7 Oct., 1968], No. 48311/69. Headings C3C and C3P. Partially expanded polymer particles containing a volatile blowing agent are made by heating the polymer particles under agitation in a dry atmosphere to soften them and cause partial volatilization of the blowing agent, then subjecting the particles under agitation to a vacuum to partially expand them and releasing the vacuum. The polymer may be polystyrene and the blowing agent pentane. An apparatus, for partially expanding polymer particles containing a volatile blowing agent is shown in Fig. 1 wherein polymer beads are fed from hopper 13 to a sealable vessel 1 which is a cylindrical ribbon blender with agitation means 3 and heated by steam jacket 7. A vacuum is applied to vessel 1 via port 33 and is released by means of vent 51. A feeder 91 allows a coolant, e.g. water, into vessel 1 when under a vacuum.
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