| 摘要 |
1537481 Expanded non-polar plastics materials ISOBOX-BARBIER and J SOULIER 23 Jan 1976 [24 Jan 1975] 3125/75 Heading C3C [Also in Division B5] Expanded plastics material is made by mixing a non-polar plastics material, such as polystyrene, containing a blowing agent with a liquid polar material, such as water, and subjecting the mixture to a super-high frequency electromagnetic radiation in a resonating cavity. The process may be used to produce moulded articles or dry pre-expanded beads for use in subsequent moulding processes. In a first embodiment (see Fig. 1) expansible polystyrene beads are extruded by a screw extruder 1, 4, 5 through an elongated PTFE die 2 located within a resonating cavity 6 connected to a magnetron 7. The hot expanded material thus formed is cooled by passage through a chamber 3. In a second embodiment (see Fig. 4) expansible polystyrene beads are injected by a screw injector 31, having an injecting head 32 located within a resonating cavity 33 connected to a magnetron 34, into a series of split injection moulds 36 carried by a horizontal turntable 35. In a third embodiment (see Fig. 3, not shown) the horizontal turntable is replaced by a vertical turntable and the moulds pass through a resonating cavity and then a cooling zone. In a fourth embodiment (see Fig. 2, not shown) the split moulds moving around a closed elongated path pass an injection head and then pass through resonating and cooling chambers. |
