GB258836A - A process of preparing cellulose for the manufacture of artificial silk and other purposes - Google Patents

Abstract

258,836. Kaufmann, W., (Assignee of Kohler, M.). Sept. 28, 1925, [Convention date]. Pulp, preparation of.-A high grade cellulose free trom hemi-cellulose is obtained by comminuting cellulosic rags, separating the cellulose fibre from any mechanical impurities, lixiviating the fibre with alkali under heat and pressure to extract the hemi-cellulose, if desired subjecting the lixiviated material to a mild bleaching, and finally drying the product. The product may be used for the manufacture of fine paper. For the lixiviating step the material is conveniently treated for 1-10 hours under a pressure of 1-5 atmospheres with a 3-20 per cent solution of unslaked lime, or a 3-15 per cent solution of caustic alkali to which sodium carbonate may be added, the solution being agitated as by circulation etc.; and it is necessary that the access of air should be prevented, for instance, the autoclave may be exhausted before or after the lye is introduced. After lixiviation the mass mav be bleached employing for this purpose a weak chlorine solution to which acid may be added. The material is finally dried in a centrifuge giving in this case a flaky product, or alternatively on the cylinders of a drying machine if a product in the form of plates or sheets is desired. During bleaching and drying a temperature not exceeding 100‹ C. is preferably employed. The Specification as open to inspection under Sect. 91 (3) (a) includes the treatment of cellulose waste other than woven material. This subject-matter does not appear in the Specification as accepted.