| 摘要 |
1,002,621. Spinning viscose. TOYO SPINNING CO. Ltd. May 15, 1963 [May 16, 1962], No. 19337/63. Heading B5B. Regenerated cellulose filaments are made by extruding viscose having a gamma number of at least 50 through a spinneret into an aqueous coagulating bath containing per litre 15 to 35 grams of sulphuric acid, 0À1 to 3 grams of zinc sulphate and not more than 100 grams of sodium sulphate to form gel filaments which are regenerated to only a very slight or a moderate degree, withdrawing the filaments from the bath in a condition wherein they have a residual gamma number less than that of the original viscose, but of at least 40, and, while they are still wet with bath liquid, causing the filaments to travel through air to to be stored in air, their period of residence and their temperature during this step in the process being such as to regenerate them further to such an extent that their residual gamma number is 20 to 35. The filaments are then stretched, and before, after or during stretching, the regeneration of the filaments is completed either in air or in a bath of dilute sulphuric acid. Alternatively the incompletely regenerated filaments may be stretched and cut into staple fibres, and the completion of the regeneration step effected in the latter. The gamma number of the viscose at the time it is spun may be 55 to 80. The coagulation bath may contain a monoamine. The cellulose in the viscose may have a D.P. of at least 300. The viscose may contain 3 to 8% of cellulose and 2 to 6% of sodium hydroxide. It may have a ball fall viscosity of at least 30 seconds. The temperature of the coagulating bath may be 15‹ to 35‹ C. The regeneration bath may contain 2 to 15 grams of sulphuric acid per litre and its temperature may be at least 60‹ C. Specification 915,356 is referred to.
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