| 摘要 |
1318608 Extruding expansible plastics UGINE KUHLMANN 16 Oct 1970 [22 Oct 1969] 49244/70 Addition to 1184688 Heading B5A [Also in Division C3] An expansible plastics material 312 is extruded from a die outlet 305 having part only of its contour contiguous with, and the remainder of its contour circumscribed by the contour of a cooled sizing die 307 through which the extrusion is pulled, e.g. by a double belt device, the expansible material contacting the contiguous sizing die surface being cooled to a harder, denser, and glossier surface skin than, and prior to, the material which expands into contact with the remaining surfaces of the sizing die 307. Various sections of extrusion and sizing die are illustrated, including to produce a rectangular section extrudate with the skin formed along one side only, or along three sides thereof, or various sections combining curved and straight sides, e.g. as in Fig. 7, or by using a pair of die outlets 305, e.g. each for differently coloured material, and the sizing die 307 of Fig. 10. The sizing die, may be regulated in temperature by circulation of a fluid, e.g. at from 20‹ to - 40‹ C. The extruded section may incorporate wires or rods. Two examples are given of the extrusion of polystyrene expanded by sodium carbonate. It is stated that the plastics may also comprise polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, or mixtures thereof, polyamides, polycarbonates, or polyurethanes. |
