Process for manufacturing a seamless tubular film and seamless tubular film

摘要

Production of a cellulose based seamless tubular film by extrusion comprises use of an internal precipitation bath comprising an aq. N-methyl-morpholine-N-oxide (NMMO) solution above the level of the spinning bath in the center of the tubular film and passage of the stretched film out of the spinning bath via a roller. A process for the production of a cellulose based seamless tubular film (I), by extrusion of an aqueous cellulose-N-methyl-morpholine-N-oxide (NMMO) spinning solution through a ring nozzle into a spinning bath whereby the spinning solution is formed into the tubular film which is transversely stretched in the air gap between the ring nozzle and the level of the spinning bath by means of an air over pressure, and the transverse stretching is reinforced by the support of a hydrostatic pressure above the level of the spinning bath in the center of the tubular film comprising an aq. NMMO solution and passage of the stretched film out of the spinning bath via a roller. Independent claims are included for (i) the resulting cellulose based seamless tubular film (I) having a maximum roughness of 0.1-0.5 mu m and an average roughness of 0.005-0.014 mu m treated with an easy peel preparation such that the easy peel preparation is reduced with decreasing maximum roughness. (ii) a device for the production of the tubular film (I) comprising a ring nozzle (1), spinning bath (3), air gap (2), tank (4) and roller (15) for the tubular film (16), and an outlet tube(11) for a solution of an internal precipitation bath (13) within the tube (12) such that the tube (12) has a smaller diameter than the tubular film (16) and a level (22) of the internal precipitation bath(13) are sealed within the tubular film (16) and the outlet opening of the outlet tube (11) is arranged at an adjustable distance above the level (22) of the internal precipitation bath (13).