GB654783A - Improvements in or relating to the manufacture of continuous films or sheets of regenerated cellulose - Google Patents

Abstract

<PICT:0654783/IV (a)/1> <PICT:0654783/IV (a)/2> <PICT:0654783/IV (a)/3> Viscose solution is extruded from a pair of separate extruding nozzles into coagulating liquid so as to form a pair of films or sheets, both sides of each film being brought into contact with the liquid until the film surface becomes non-tacky, and the films are then brought together in surface contact and are fed together through a treating liquid with only one side of each exposed until the treatment is completed; the films are then separated and passed through separate drying zones. The nozzles may feed into the same or separate coagulating baths. If desired, two or more pairs of nozzles may be employed to form several pairs of films which are treated so that only one surface of each film is exposed to the treating liquid. As shown in Fig. 1, a pair of extrusion nozzles 1 and 2 extrude viscose into baths 3, 4 and the regenerated cellulose films 7, 8 are brought into contact at a guide 11. They are then passed with only one surface of each exposed, through baths 15 for washing, desulphurizing, bleaching, and softening. They are passed over upper and lower guides 19. After emerging from the baths, the films are separated and passed over separate series of heating and drying rolls 20, 21, and they are then wound up separately. As shown in Fig. 2, four films are treated in pairs so that one surface of each is exposed to the treating liquid. Two nozzles 30 are arranged to extrude viscose into each of two coagulating baths 32. The coagulated films 35 are brought together in pairs and then fed through treating baths 38. The four films are fed together over bottom guides 40 but the pairs of films are passed over separate upper guides 41, 42. Guides 42 are of larger diameter so that the pairs of films are separated in baths 38 and one surface of each web is exposed to the treating liquid. Instead of large guides 42, pairs of guides 43, Fig. 3, may be used. After emerging from the final liquid treating bath the four films are separated and passed over separate sets of drying rolls. By bringing the films together for the liquid treatment there is less danger of breakage and crinkling.