GB747732A - Improvements in or relating to the production of reinforced plastic tube - Google Patents

Abstract

747,732. Synthetic resin tubes. POLYCHEMICAL DEVELOPMENTS, Ltd. May 10, 1954 [May 18, 1953], No. 13829/53. Class 99(2). A tube of plastic material, e.g. polyvinyl chloride or cellulose acetate butyrate plastic known as Tenite II Grade 435E, has an intermediate reinforcing layer 2 including at least a proportion of composite threads having a core of wire onto which textile yarns are bound or gripped. Preferably, the threads comprise cotton, rayon or nylon yarns twisted in one direction around a core of high-tensile steel wires, one or more wires being twisted over the yarns in the opposite direction to bind the yarns to the core wires, and the outer wire or wires being spaced well apart so that the yarns are gripped and seized against the core wires at intervals whilst being exposed for bonding to the plastic material between the convolutions of the outer wire or wires. The wires may be preformed before coating with a plastic material the same as or different from that employed for the wall of the tube. As shown in Fig. 1, a composite thread is wound into helical grooves 3 cut in a tube 1, and an outer cover 4 is extruded over the threads ; alternatively, a thread is wound into each of a number of parallel grooves. In a modification, Fig. 2 (not shown), the reinforcing layer is braided around the inner tube 1. The reinforcement may comprise a tubular fabric base produced by weaving, braiding, plaiting or knitting, or a flat fabric placed around a former and stitched or otherwise secured along the seam, such reinforcements being mounted on an expansible mandrel and a synthetic resin being applied thereto by rollers and calendered in position ; alternatively, the resin is applied by jets or sprays, the rollers serving to force, the resin into the reinforcement by pressure. Where heat treatment of the resin is required this is effected by the use of a heated pressure roller. If a flexible tube is required the plasticized resin is used and is applied in a partially cured or partially polymerized form and converted to its final state after the impregnation or application of the tubular base. Specifications 712,047 and 747,726, [both in Group VIII], are referred to.