| 摘要 |
Viscose rayon, suitable for the production of staple fibre, is obtained by spinning into a dilute sulphuric acid coagulating bath, containing at least 50 grams per litre of sodium sulphate, a viscose prepared from cellulose pulp having a degree of polymerization of at least 700, without ripening of the alkali cellulose and without ageing of the viscose, the viscose having a viscosity of at least 300 poises and a gamma value higher than 60, and thereafter fixing the filamentary product by treatment with a hot aqueous liquid. The filaments obtained have a high resistance to breaking by repeated bending. The viscose may have a cellulose content of 5.5 to 7.5 per cent. and a caustic soda content of 3 to 5 per cent. The coagulating bath may contain up to 30 grams per litre of sulphuric acid and 80 or more grams per litre of sodium sulphate. The viscose may be spun vertically upwards from a horizontal spinneret and the filaments may be subjected to stretching continuously with their production. The xanthate filaments may be treated with boiling water to regenerate the cellulose. The filaments may be cut to form staple fibre before the regeneration treatment, or a bundle of the regenerated cellulose filaments may be stretched in a continuous manner so that the filaments are broken to form a sliver of short fibres. In an example, cotton linters, the cellulose of which has a degree of polymerization of 700-800, are mixed with caustic soda and then pressed. The alkali cellulose is not ripened but is shredded and xanthated with 55 per cent. of carbon disulphide, calculated on the alpha-cellulose content of the pulp, at 25-30 DEG C. The treatment is carried out in a vacuum or inert atmosphere. The xanthate is worked into a paste with caustic soda solution at -5 to +5 DEG C. and the product is dissolved in dilute caustic soda or water to produce a viscose containing 6 per cent. of cellulose and 3 to 5 per cent. of caustic soda. The viscose is not aged before it is used in the spinning operation. The viscose is spun into dilute sulphuric acid containing more than 50 grams per litre of sodium sulphate, and the xanthate filaments obtained are stretched and then converted to cellulose by treatment with boiling water. Specification 685,631 is referred to.
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