GB520560A - A method of manufacturing flexible threads, tapes, sleeves, tubes, coverings and the like - Google Patents

Abstract

520,560. Extrusion moulding. ROST, H. F. Nov. 8, 1938, No. 32380. [Class 87 (ii)] [Also in Group IV] Flexible threads, tapes, sleeves, tubes, hoses, coverings and the like of polymerization or condensation products having rod or chainlike molecules are obtained by introducing the substance in a plastic condition into a tapered nozzle of which a substantial length terminating in the nozzle is of substantially constant crosssection and which is symmetrically arranged around a core coaxial with the nozzle, moving the plastic mass to the outlet, drawing it so as to stretch it by friction with the inside surface of the nozzle, and solidifying or hardening it as it leaves the nozzle outlet. The mass may be rendered plastic by heating or by mixing it with solvents or plasticizers. Setting subsequently to shaping may be effected by chemical treatment, or by cooling. When tubes or threads are to be made, the core may be fixed in the nozzle, but for sleeves or coverings the article to be covered, e.g., an electric conductor or cable, may itself serve as the core and mover with the shaped mass. After a conductor has been provided with one sleeve or coating it may be passed again through the same or a different nozzle and be provided with successive coatings of the same or different dielectric constants. The plastic material may be of a polyolefine, polystyrol, polyvinyl carbazol, polyvinyl chloride or acetate, polyacrylic or polymethacrylic acid, polybutadiene, polymerized acetylene compounds, polymerized vegetable oils, cyclic ketones, or methylene ketones, condensation products of polyvinyl compounds with aldehydes, or aniline-formaldehyde condensation products. Polyvinyl chloride may be dissolved in hot chloronaphthalene or other solvent to form a plastic mass which on cooling sets to a stiff rubbery gel. As shown in Fig. 1, the semi-solid mass is contained in vessel 1 provided with piston 7. Parts 2 and 3 form a tapering nozzle. A core 9, which may be a conductor or cable core, is passed through vessel 1 and the nozzle. A cooling or setting device 11 is provided. When an air space is required between sleeve and core, the mouthpiece 5 may protrude outside orifice 4. The plastic mass is stretched as the core is drawn through the nozzle. The core is preheated as it passes through vessel 1 before contacting with the plastic mass. The device 11 may be replaced by a chemical setting bath if the mass has been made plastic with solvents. As shown in Fig. 2, the device is provided with a fixed core 12 held by a centre-piece 13. Fat or grease may be injected through openings 16 so as to prevent the sleeve 10 from sticking to the core. As shown in Fig. 3, a tapering centrepiece 17 is provided. If the tip 18 terminates inside the nozzle, a solid thread is produced, but if it extends beyond the nozzle, a hollow thread or tube is obtained.