| 摘要 |
1,020,169. Spinning viscose. CHIMIOTEX S.A. Nov. 6, 1963 [Nov. 6, 1962; Dec. 6, 1962], No. 43848/63. Heading B5B. Regenerated cellulose filaments of homogeneous microfibrillar structure are produced by spinning a viscose having a gamma index of at least 45 and a viscosity of at least 150 poises at 18‹ C. and containing 1À5 to 9% of total sodium (calculated as sodium hydroxide) and at least 3% of total cellulose having a degree of polymerization of at least 400, the viscose being prepared using at least 35% of carbon disulphide based on the weight of the alphacellulose, into an aqueous coagulating bath (bath A) maintained at a temperature below 10‹ C., containing less than 40 g./litre of sulphuric acid, from 10 to 100 g./litre of sodium sulphate and less than 1 g./litre of zinc sulphate, and stretching the filaments formed at least 100% before passing them into an aqueous degassing bath (bath E) of hot dilute sulphuric acid maintained at 95‹ C. or above. The filaments after leaving bath A may be freed from excess liquid by compression. Bath A may contain 5 to 25 g./litre of sulphuric acid and 10 to 40 g./litre of sodium sulphate. The temperature of bath A may be between 2‹ and 8‹ C. The filaments leaving bath A may be passed into a second bath (bath B) having the same composition and temperature as bath A. The filaments leaving bath A may be passed into an intermediate aqueous bath (bath C) of dilute sulphuric acid containing an aldehyde and maintained at below 25‹ C., then into a bath (bath D) of dilute aqueous sulphuric acid which also contains an aldehyde, the filaments being stretched after leaving bath C but before leaving the bath D, and finally into bath E. The viscose or bath A may contain an aldehyde such as formaldehyde. Bath C may have the same composition, apart from the aldehyde, and the same temperature as bath A. Bath D may be maintained below 25‹ C. and may have the same composition and temperature as bath C. |
