| 摘要 |
Tubular extrusion (16) of thermoplastic solution, composed of non-derivative cellulose, tertiary amine oxide cellulose solvent, and water, is initiated by extruding the solution down from an annular die (12) through an air gap (24) of at least 304 mm into an outer bath (20) of non-solvent liquid to form a seamless extruded tube. The solvent is extruded about a mandrel (26) depending from the die, with a smaller diameter shaft (28) and a larger lower end (30). The mandrel shaft can be extended to change the spacing of its lower end from the die. The shaft is withdrawn into the die to locate the lower end of the mandrel above the surface (22) of the non-solvent liquid in the outer bath and extrusion starts with the lower end above the surface. The leading end (36) of the extruded tube is drawn along the mandrel, over the mandrel end, through the space between the end and the liquid surface, and down into the bath while extending the shaft from the die until the lower end of the mandrel is located in the non-solvent liquid. Also claimed is apparatus for the above process. |
