Improvements in or relating to the production of extruded shapes from organic thermoplastic materials

摘要

Organic thermoplastic material substantially free from volatile solvents is extruded, hot, into a stream of inert fluid, the stream having a temperature below the softening point of the material and travelling at high velocity in the direction of travel of the extruded body. The body is maintained in the (comparatively cool) stream until it has become form-stable. Fig. 2 shows an arrangement in which a screw 3 extrudes strands 9 of material through a die plate 7 into ducts 11 through which is blown compressed air from a pipe 14. The air cools the strands, maintains them out of substantial contact with the ducts and, by frictional pull, tensions them. The strands are cut into pellets 19 by a rotating knife 17. There may be one pipe 14 for each duct. The fluid may be water or aqueous solutions. In a modified single-die arrangement, for making sheet, the air issuing at the exit end of the duct is collected and led away through a vertical pipe. Specifications 300,672, 322,557, [both in Class 2 (ii)], 371,343, 530,468, 534,243 and 570,139, [Group V], are referred to. The Specification as open to inspection under Sect. 91 states that the cutting may be omitted, the material being collected in long lengths. This subject-matter does not appear in the Specification as accepted.