Patent GB-994059-A (GB)
Title: Method and apparatus for manufacturing collagen tubing
IPC: B29C48/10
Filed: 1961-06-26
Abstract: 994,059. Collagen tubular films. JOHNSON & JOHNSON. June 26, 1961 [Jan. 16, 1961], No. 23105/61. Heading B5B. Tubular collagen film or casing is made by extruding a continuous fragile tube from a fluid mass of swollen collagen fibrils made by acid swelling of dehaired hide and having a collagen solids content of between 2.5 and 6% by weight, applying a coagulant to the tube, hardening the coagulated tube, washing coagulant from the tube and drying the tube. The tube, which may be extruded from an aqueous suspension of collagen fibrils, from an extruder of the type disclosed in Specification 988,875, is conveyed by entrainment successively through a series of moving baths of conditioning liquids, each liquid being withdrawn at the end of its respective bath while maintaining the rate of flow of the bath and of the tube immersed therein, and successive conditioning liquids being supplied to form successive baths at points along the path of travel of the tube. The coagulating and hardening liquids may be aqueous solutions of ammonium sulphate and of alum respectively. The hardened tube may be plasticized in a bath containing carboxymethyl cellulose. The tube may be dried, while inflated, by heated air currents. The drying step reduces the wallthickness of the tube. In one embodiment, an extruded tube is partially coagulated in a vertical column of liquid constituting a housing surrounding and extending upwardly from the extruder orifice. The partially coagulated tube C (Figs. 1 and 2) is fed by godet 62 downwardly into a penstock 40 and thence into the uppermost of closed troughs 12B. Coagulant is circulated from reservoir A to penstock 40 and troughs 12B via conduits 67, 80 and pump 64. Tube C moves by entrainment through each of troughs 12B until it reaches D, where it is removed from the entraining liquid by godet 82, and is transferred via penstock 88 into the uppermost of troughs 120. Hardening liquid is circulated by pump 96 from reservoir 94 to troughs 120 via conduits 99, 100, 124. A spiked roller 160 pierces spaced holes in tube C to avoid distortion due to enclosed air pockets. The hardened tube C emerges at 113 and passes over godet 116 into container 118. Godets 62, 82, 116 may be provided with means for transmitting variable torque. The system of troughs may be extended to accommodate further conditioning e.g. plasticizing and washing, liquids. In a further embodiment (Fig. 16) a system of open troughs may be used instead of the closed trough system of Fig. 1. Tube C is guided by godets 206, 208 through horizontal or inclined troughs in which conditioning liquids flow. The tube C is then dried by passage through a drying chamber (Figs. 20 and 24) through which heated air is circulated. The tube is passed into the chamber by rollers 302, 394, 396 and is transferred through the chamber by double-tracked godets 360, 364 while supported by idlers 366, 368. Cylindrical manifolds 374 (Fig. 25) direct heated air jets on to the tube C. The tube emerges from the drying chamber at 370, and is inflated as far back as rollers 302 by air supplied at valve 390. Endless belt 410 is provided for threading the air-hose through to rollers 302 at start-up. Rollers 460, 462 maintain air pressure inside the tube. Albumin may be blown on to the interior surface of the tube via shirring mandrel 400. Specification 991,183 also is referred to.