Patent GB-1030207-A (GB)
Title: Composite tubing and method of manufacture thereof
IPC: B29C48/09
Filed: 1963-08-23
Abstract: 1,030,207. Flexible pipes. SAMUEL MOORE & CO. Aug. 23, 1963 [Aug. 30, 1962], No. 33575/63. Heading F2P. A composite tubing T comprises an inner tube 10 of extruded thermoplastic elastomeric polyurethane material, a plurality of strands 14 disposed about the inner tube and forming a reinforcing member 12 therefor, each strand including a multiplicity of separate filaments, an elastomeric polyurethane adhesive 15 bonding the reinforcing member to the inner tube and an outer sheath 16 of extruded thermoplastic elastomeric polyurethane covering the reinforcing member, said adhesive bonding said outer sheath to said reinforcing member and to said inner tube and encapsulating the strands while permitting controlled movement of inner filaments of each strand within its respective adhesive envelope. The polyurethane adhesive is composed of a prepolymer, a chain extender and a catalyst, a suitable range of proportions being quoted and suitable examples of each being specified. The adhesive is applied by a suitable applicator and its viscosity is controlled during the application by maintaining it within a temperature range such that it is not absorbed into the strands 14 but encapsulates them and may pass through the interstices between them. The reinforcing strands are prefably composed of polyester filaments, movable with respect to one another. Other possible materials for the strands are nylon and rayon. The polyurethane resins for the inner tube and outer sheath are of the same general composition and may include certain specified blends of proprietary compounds. The inner tube is extruded hot, being supported by internal air pressure as it issues from the extrusion die. It is set against stretching by being passed through a short water bath, further cooled in a second water bath, and wound on a reel. From the reel the tubing is drawn through an adhesive applicator, after which it is preferably passed through a drier to hasten the setting of the adhesive. The adhesive-coated tube then passes through a machine which braids on to it one or more layers of reinforcing material and is wound as another reel. After the reinforcing sleeve has been applied to the inner tube and before the adhesive material has been cured, the tube is taken to an extruder for application of the outer sheath. The braided tube is drawn off the reel and fed through another adhesive applicator and anothor drier, after which it is passed through a vacuum apparatus for ensuring proper thickness of the adhesive coating in order to pass through the extrusion head which applies the outer polyurethane sheath. The material is dried before it is extruded and adheres to the braided tube, and the sheathed tubing is quenched and cooled in a water bath. The adhesive reaches a finally cured state at room temperature, or its curing may be accelerated by warming the tubing. It is stated that, due to the non-penetration of the adhesive into the individual strands, the strands adjust the shape of their cross-section when the tubing is bent with the result that, and also because of the elasticity of the inner tube and outer sheath, the tubes can be easily bent without causing crimping.