Patent GB-824362-A (GB)
Title: Method of producing sausage casings and apparatus therefore
IPC: B29C48/19
Filed: 1956-11-20
Abstract: <PICT:0824362/IV (a)/1> Sausage casings having one or more narrow longitudinal stripes differing in appearance from the remainder of the casing are continuously produced by supplying a film-forming solution of cellulose or of a cellulose derivative to an annular extrusion nozzle through a conduit, injecting through one or more orifices in the wall of the conduit a striping composition in such a manner that it forms at least one narrow stream on the surface of the column of film-forming solution moving through the conduit and flows in this form with the stream of film-forming solution substantially without mixing with it, the striping composition consisting of a solution of a film-forming material which is compatible with the cellulose or cellulose derivative present in the main film-forming solution and being of such a nature or containing such a substance that the stripe or stripes in the final casing differ in properties from the remainder of the casing and are detectable; the composite stream of film-forming solution is then extruded through the extrusion nozzle into a coagulating bath.  As shown, clear viscose is supplied under pressure through a supply line 10 to an extrusion nozzle 20 having a tubular passage 24 terminating in an annular orifice through which the viscose is extruded into a vertical cylindrical vessel 34 through which a coagulating and regenerating solution is passed by means of inlet 36 and outlet 38.  The same solution is passed through the interior of the seamless tubing 28 thus formed by means of the supply pipe 42 and overflow pipe 44. Simultaneously an opaque viscose containing 0.8% of titanium dioxide is supplied under a pressure 2 to 4 pounds higher than the pressure of the clear viscose through an inlet 19 into a chamber 18 surrounding a portion of the main viscose supply line 10 which is provided with a row of circumferentially spaced orifices 14, each of which supplies the opaque viscose in the form of a stripe on to the exterior of the column of clear viscose moving on towards the extrusion nozzle 20.  The striped tubing is withdrawn from the bath 34 and processed and dried to a flattened tubular film in the usual manner.  The stripes of opaque regenerated cellulose on the surface of the casing may be overlaid with a layer of clear regenerated cellulose, in order to give them a lustrous appearance, by supplying clear viscose under a pressure to a chamber surrounding a portion of the main viscose feed pipe between the chamber supplying opaque viscose to the main viscose stream and the extrusion nozzle.  The orifices in the portion of the pipe surrounded by the second chamber are somewhat larger than those in the portion of the pipe surrounded by the first chamber in order to ensure that the opaque viscose stripes are completely overlaid by clear viscose stripes.  The viscose used for forming the stripes may contain carbon black, dyes, powdered mica, fluorescent materials or magnetic materials such as iron powder or magnetic iron oxide powder.  The striping viscose need not be opaque.