Patent ID: 6565796
Filing Date: 2003-05-20
Classification: B29C,B29K

Abstract:
A method of diametrically sizing a tubular extrusion composed of a thermoplastic cellulose solution comprising:a) forming a seamless cellulose tube by downwardly extruding a tube of thermoplastic solution composed of nonderivatized cellulose, a tertiary amino oxide, and water through an air gap and into a nonsolvent bath; b) during the course of extruding, causing the extrusion to pass over and about a vertically oriented mandrel having a sizing portion generally in the shape of a hollow cylinder that has a diameter larger than the extruded tube and having a diameter at the point the sizing portion is adjacent to a conical transition cylinder being the same as the adjacent edge of the conical transition cylinder and a diameter of a lowermost end face being greater than the diameter of the widest edge of the conical transition cylinder, the mandrel having a lower end disposed below the level of the bath and a smooth outer surface provided with a plurality of openings to the interior of the hollow cylinder; c) passing gas bubbles evolving from the extruded tube at the interface between the extruded tube and sizing portion through the openings and into the hollow interior; and d) removing the gas from the hollow interior upwardly through the mandrel.