GB830820A - Improved process for viscose production - Google Patents

Abstract

A controlled depolymerization of cellulose is effected by subjecting cellulose to ionizing radiation of an intensity between 0.05 and 60 watt-second/gram of cellulose. The ionizing radiation may be of the particle or the electromagnetic kind. In the manufacture of viscose in which cellulose is alkalized and treated with carbon disulphide, the xanthate thus formed being dissolved in sodium hydroxide solution and filtered to yield viscose, the ionizing radiation may be applied at any stage in the process. Alternatively a short period of irradiation of the alkali cellulose may be supplemented by irradiation of the viscose to give a product of the desired viscosity, the latter serving to indicate the degree of depolymerization. Irradiation may be carried out between room temperature and -78 DEG C. on cellulosic raw materials, e.g. wood pulp in sheet or shredded form and cotton linters. Wood pulp in continuous sheet form may be irradiated as it is unwound. It is preferred to irradiate cellulose sheet of low moisture content. Examples describe the irradiation of cotton linters, wood pulp and viscose with electron beams and with X-rays from a gold target which has been bombarded by electrons.ALSO:A controlled depolymerization of cellulose is effected by subjecting cellulose to ionizing radiation of an intensity between 0.05 and 60 watt-second/gram of cellulose. The ionizing radiation may be of the particle or the electromagnetic kind, protons, neutrons, alpha-particles, deuterons, beta-particles, gamma radiation and X-rays being specified. In the manufacture of viscose in which cellulose is alkalized and treated with carbon disulphide, the xanthate thus formed being dissolved in sodium hydroxide solution and filtered to yield viscose, the ionizing radiation may be applied at any stage in the process. Alternatively, a short irradiation of the alkali cellulose may be supplemented by irradiation of the viscose to give a product of the desired viscosity, the latter serving to indicate the degree of depolymerization. Irradiation may be carried out between room temperature and -78 DEG C. on cellulosic raw materials, e.g. wood pulp in sheet or shredded form and cotton linters. Wood pulp in continuous sheet form may be irradiated as it is unwound. It is preferred to irradiate cellulose sheet of low moisture content. Examples describe the irradiation of cotton linters, wood pulp and viscose with electron beams, and with X-rays from a gold target which has been bombarded by electrons.