| 摘要 |
Hollow artificial filaments, tubular films and tubes are produced by melt-extruding a synthetic thermoplastic resin through extrusion nozzles, each nozzle being provided with a core in the form of a hollow mandrel, the interior of which communicates with the atmosphere or with a source of a cavity-forming medium at slightly super-atmospheric pressure, the interior of the mandrel being provided with a coaxial tube, the outside diameter of which is less than the inside diameter of the mandrel and the end of which remote from the extrusion orifice is in communication with a duct which, in turn, is in communication with a source of supply of a cavity-forming medium at slightly superatmospheric pressure when the interior of the mandrel is in communication with the atmosphere, and vice versa. The space between the extrusion orifice and the hollow mandrel may be provided with one or more cross pieces. Both the interior of the hollow mandrel and the coaxial tube within it may be in communication with the same source of supply of cavity-forming medium so that the latter may be recycled. Either the hollow mandrel or the coaxial tube may project beyond the inlet surface of the spinneret plate in the form of a chimney in order to facilitate the discharge of the cavity-forming medium into the atmosphere. The cavity-forming medium may be a gas, a liquid or a freely-flowing particulate solid. Specification 859,325 and Swiss Specification 222,772 are referred to.ALSO:Hollow artificial filaments, tubular films and tubes are produced by melt-extruding a synthetic thermoplastic resin through extrusion nozzles, each nozzle being provided with a core in the form of a hollow mandrel, the interior of which communicates with the atmosphere or with a source of a cavity-forming medium at slightly super-atmospheric pressure, the interior of the mandrel being provided with a coaxial tube the outside diameter of which is less than the inside diameter of the mandrel and the end of which remote from the extrusion orifice is in communication with a duct which, in turn, is in communication with a source of supply of a cavity-forming medium at slightly superatmospheric pressure when the interior of the mandrel is in communication with the atmosphere, and vice versa. The space between the extrusion orifice and the hollow mandrel may be provided with one or more cross pieces. Both the interior of the hollow mandrel and the coaxial tube within it may be in communication with the same source of supply of cavity-forming medium so that the latter may be recycled. Either the hollow mandrel or the coaxial tube may project beyond the inlet surface of ths spinneret plate in the form of a chimney in order to facilitate the discharge of the cavity-forming medium into the atmosphere. The cavity-forming medium may be a gas, a liquid or a freely-flowing particulate solid. Specification 859,325 and Swiss Specification 222,772 is referred to.
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