Patent GB-827642-A (GB)
Title: Elastic yarn and cord and weatherstrip made therefrom
IPC: B29D99/00
Filed: 1956-03-26
Abstract: An elastic "strand," i.e. a yarn, thread, cord, rope, or like elongated assembly of fibres, comprises rubber fibres in progressive overlapping arrangement and bonded to each other at their points and areas of contact.  The strand may also comprise non-elastomeric fibres, i.e. natural and synthetic fibres or fibres and filaments made by slitting, cutting or shredding non-fibrous films such as waste regenerated cellulose film, which may be in admixture with the rubber fibres or comprised in yarns or threads wrapped or braided around the elastic strand (and bonded thereto if applied prior to curing or vulcanizing the rubber content) or in other strands intertwisted therewith.  Two or more of such elastic strands may be intertwisted and wrapped with yarn and the strands and/or wrapping or braiding may be bonded together if assemled prior to curing the rubber.  In forming the strand, rubber fibres may be collected on a supporting core such as a wire, cellulose fibre yarn, or a thermoplastic-resin filament, which is subsequently broken at a multiplicity of spaced points.  The non-elastomeric fibre content may be augmented or replaced by particulate material, e.g. cork dust, wood flour, leather dust, fibrous flock, or abrasive particles such as emery dust.  In a method of producing the "strand" a spraying liquid, e.g. benzene, naphtha, toluene, xylene, cyclohexanone, ethylene chloride, methylene chloride, carbon tetrachloride, nitroparaffins, or ketones, containing in solution or dispersion 5-50% of rubber fibreforming material and, optionally, including refining materials such as carbon black, curing or vulcanizing agents such as sulphur, accelerators, antioxidants, plasticizers, detackifying agents such as paraffin wax or stearic acid, colouring agents, and fillers such as clay, whiting, kaolin and french chalk, is extruded through an orifice to form a liquid stream which is attenuated, as by a stream of gas, e.g. steam, air, nitrogen, or carbon dioxide, partially set to render it adhesive and broken, as by the gas stream, into fibres which are collected as a strand and bonded together as the rubber is cured.  As shown in Fig. 1, spraying liquid, pumped through a conduit 4, is extruded from orifices in spray tips 5 of a spraying unit 3 and a stream of gas, which may be heated, is forced through a conduit 6 and nozzles 7 at a velocity exceeding the velocity of extrusion of the liquid <PICT:0827642/IV (a)/1> <PICT:0827642/IV (a)/2> <PICT:0827642/IV (a)/3> <PICT:0827642/IV (a)/4> so that the liquid stream is attenuated and broken transversely into fibres 10: the solvent is evaporated partially to harden the fibres.  A secondary stream of gas, e.g. steam or air, the temperature of which may be regulated so as to remove all solvent and set the fibres and by means of which the particulate material may be introduced, is supplied by a blower 8 through an intake 9 to the base of a tower 1 wherein a spiral fin 2 directs the stream into a vortex or swirling gas flow to create suction along the axis of the tower towards and about which the fibres are thereby directed and assembled.  The fibres are continuously withdrawn in the form of a strand, cured in a heating chamber 12, and taken up on a spool 13.  The unit 3 may be replaced by the unit shown in Fig. 3 wherein the liquid is supplied through a hollow shaft 37 to a chamber 34 formed by a flanged disc 30 and cover plate 33 and is extruded from nozzles 32: rotation of the unit causes vanes 36 of an impeller to produce a gaseous blast which directs the fibres over a conical shell 5 towards the axis of the tower 1.  As shown in Fig. 2 the liquid is extruded through spray tubes 17 of a unit 15 and is subjected to primary and secondary gas streams emerging from nozzles 16 and entering a tower 14 from a blower 18, and the fibres are collected on a core 19 to form a strand 22 which is dusted with a detackifier in a chamber 23, heated in a chamber 24, and is tensioned between rollers 28 and 29 to break the core. The unit 15 may be replaced by the apparatus shown in Fig. 4 wherein a core thread 46 passes through a guide tube 45 of a hollow shaft 44 which rotatably carries a chamber, formed by a flanged disc 38 and cover plate 41, from which the fibre-forming liquid is extruded through nozzles 40 and is subjected to an air stream created by vanes 43 of an impeller.  Specifications 794,725 and 827,641 are referred to.