| 摘要 |
1480324 Foam coating pipes KABELUND METALLWERKE GUTEHOFFNUNGSHUTTE AG 27 May 1976 [7 June 1975] 22078/76 Addition to 1458490 Heading B2E [Also in Division B5] A method of continuously producing thermally insulated piping comprises applying a coating 10 of predetermined thickness of an expandable cross-linkable synthetic resin material onto a metal tube or a cladding carried thereby, and then expanding the material, wherein the material undergoes crosslinking which is initiated before the expansion, wherein the material is progressively heated in an extruder from the inlet to the outlet thereof, and immediately before leaving the extruder has a temperature above the reaction temperature of a cross-linking agent and an expanding agent of the material. Preferably a screw 3 feeds the material to a nozzle 6, the material being heated by shearing caused by rotating a hollow pin 5 housing the pipe 9. The composition may be fed as a mixture of particulate components, the resin being polyethylene, the cross-linking agent being dicumyl peroxide, and the blowing agent being azodicarbonamide. The coated pipe may be passed through a heated die. |
