| 摘要 |
1,137,857. Making viscose rayon. RAYONIER Inc. 16 Feb., 1966 [20 July, 1965], No. 6832/66. Heading B5B. Viscose rayon filaments having an average conditioned tenacity of 4.3 to 6.5 g.p.d., a wet modulus of 1 to 2 g.p.d., a wet tenacity of 3 to 5 g.p.d., an elongation of from 8 to 12 per cent, and a solubility in aqueous 6.5% sodium hydroxide solution of less than 4.5%, which filaments have cross-sectional shapes which are mostly smoothly curved and have a protuberance on one side. They may be made by preparing a viscose from cellulose scanthate of 450 to 800 D.P., which viscose has a gamma number of 40 to 90, an NaCl salt index of 7 to 12 and contains a regeneration retarding modifier, extruding the viscose into a coagulating bath maintained at 18 to 30‹ C., which bath contains 3 to 9% by weight H 2 SO 4 , 7 to 18% of Na 2 SO 4 , 0.2 to 2% formaldehyde and 1 to 6% by weight of zinc sulphate. The coagulated filaments are stretched to such an extent that they are elongated by 110 to 250% . their length before being stretched, their stretching at this stage prior to their regeneration being at least 60% of the total stretch which they are to receive. Thereafter and while they are being completely regenerated in contact with a regenerating liquid at 60‹ to 100‹ C. they are stretched by at least an additional 30% in length, but by not more than 40% of the total stretch or beyond filament damage. The regenerating liquid is preferably a 0.5 to 5.0% by weight aqueous sulphuric acid solution. The modifier is preferably a mixture of dimethylamine and polyethylene glycol, preferably in the proportions of 1.0 to 30% by weight and 0.5 to 2.5% by weight respectively. The spin bath preferably contains formaldehyde and zinc sulphate (the proportion of the latter being expressed as the anhydrous salt) in the proportions shown in the shaded area of Fig. 1. The spin bath may contain 0.01 to 0.1% by weight of a surface active agent such as lauryl pyridinium chloride.
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