Patent ID: 6821591
Filing Date: 2004-11-23
Classification: A22C,B29C,B29K,Y10T

Abstract:
A method for producing a seamless tubular film based on a cellulose base comprising: extruding an aqueous cellulose-N-methyl-morpholine-N-oxide spinning solution through an annular die in a spinning bath, wherein the spinning solution forms said tubular film,laterally drawing said film in an air gap between said annular die and said spinning bath by stabilizing air pressure in said tubular film, wherein the level of hydrostatic pressure from an inner spinning solution formed inside said tubular film extends above said spinning bath, said inner spinning solution comprising an aqueous cellulose-N-methyl-morpholine-N-oxide solution that supports and intensifies said lateral drawing; passing the tubular film that has been expanded by the lateral drawing process by a turning point in the spinning bath, and directing said film out of said spinning bath.