GB350515A - Improved process and apparatus for the production of viscose - Google Patents

Abstract

<PICT:0350515/IV/1> For the production of viscose, the materials, starting with cellulose, are led in continuous uninterrupted working operation through apparatus in which the steps first in the preparation of alkali cellulose, then in sulphidizing, and finally in the obtaining of filtered and deaerated viscose are carried out continuously and in sequence on the moving materials. As illustrated, the cellulose, either in the form of sheets or as cotton fleece, is passed between endless wire net bands through a steeping vessel 1, and after steeping, the material is delivered if necessary with the aid of a beater 2 to a worm system 3 in which disintegration preferably with simultaneous ripening by the application of heat, takes place, the heating being effected by the use of separate jackets to the individual worms, or by enclosing the system in a single heating chamber, or by passing hot gases, which may contain oxygen, through the worms. Additional soda lye may be supplied as the material passes through the worms. In order to disintegrate the material, the worms may be grooved or provided with teeth &c., and for the further breaking up of the material it is convenient to pass the latter through intermediate gratings 4 which serve as bearing members to the worm shafts, and before or behind these gratings there may be arranged others which rotate with the shafts. The last worm delivers into a series of emptying members 6 or into a collecting container or on to a conveyer band or bucket elevator, and from these the moist fibrous mass is pressed or centrifuged to the desired weight as by passage between wire nets through pressure rollers, or by means of suction drums which can be assisted by squeezing rollers, or by centrifuges 7, the material delivered from the latter being again collected as by a worm 8, and if necessary again loosened. Sulphidizing may be carried out in a rotating pipe 9 adapted to be heated or cooled as by a jacket or by liquid sprays 9a; carbon disulphide is introduced through a spray pipe 11, and the escape of vapours is prevented by sliding seals 10 at the ends of the pipe 9 and by delivery and discharge chambers 12, 13 which are kept well filled with material. In the place of a rotary pipe, there may be used for sulphidizing, conveyer worms or bands, and the carbon disulphide may be employed in the form of vapour. If xanthogenate formation is to be effected by the use of emulsions of carbon disulphide and soda lye or by emulsification of carbon disulphide with alkali cellulose suspended in soda lye, then this emulsification can be effected in the alkalizing worms, or the flow of material may be divided for the purpose of emulsification, the several portions being re-combined and being passed for further reaction through conveyer worms in a rotating pipe. The xanthogenated material collecting in the chamber 13 is passed by means of a conveyer 15 through a chamber provided with suction pipes 16 for removing excess carbon disulphide, air inlet pipes 17 in advance of these being provided in order to relieve the chamber 13 of a partial vacuum. The material then passes through conveying worms in which solution is effected, and thereafter the solution, after filtration and ripening, is passed through a continuously-operating deaerating device.