| 摘要 |
In the production of filaments from viscose by extruding the viscose into a primary bath containing sodium sulphate, zinc sulphate and sulphuric acid, in proportions to prevent complete regeneration of the viscose, and then stretching the filaments while passing them through a secondary dilute acid bath maintained at a temperature above 60 DEG C. and containing less acid and salts than the primary bath, the formation of zinc sulphide deposits is inhibited by adding a persulphate to at least one of the baths. The persulphate may be that of sodium, potassium or ammonium and it may be used in either bath or in both. Anion-active compounds may also be added to the secondary bath, specified compounds including soap, sulphonated alcohols, sulphonated hydroxy benzenes having an alkyl substituent of 8 or more carbon atoms, sodium b -oleylethane sulphonate, sodium b -oleylamidoethane sulphonate, sodium alkyl-aryl sulphonates and long-chain alcohol sulphates. The acid and salts for the secondary bath may be those carried over from the primary bath. The primary bath may contain magnesium sulphate. Specifications 467,500, 652,594, 661,940 and 683,646 are referred to.
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