| 摘要 |
1315585 Drainage ARMOSIG 14 Jan 1971 [29 May 1970] 1972/71 Heading A1B [Also in Divisions B5 and F2] A P.V.C. foam tube 12 is produced by extruding (see Divisions B4-5) a P.V.C. composition containing expanding agent, and which is sized by passage through a circulating fluid cooled sizing die 3, against which it may be urged by internal air pressure. The tube may be used for agricultural, sanitation, or drainage purposes, for carrying unpressurised hot fluids, as ventilation ducts, cast into concrete as cable conduits, and for roller blinds, windows, doors and partitions. The dimensions and densities are given of exemplary tubes, in comparison with equivalent performance non-foamed P.V.C. tubes, the foamed P.V.C. tube being preferably of 0.6 to 1.0 gm/cc., and of a modulus of elasticity greater than 16,000 kg/sq cm. |
