Patent GB-811115-A (GB)
Title: Improvements in and relating to viscose spinning and products obtained thereby
IPC: D01F2/08
Filed: 1955-07-13
Abstract: Filaments, fibrous and like products are made by extruding into an acid coagulating bath containing zinc (the acid in the bath being preferably sulphuric acid), viscose containing an organic substance which is soluble therein and which forms with the zinc in the shaped product a zinc chelate which is stable in liquids having a pH above about 7 and unstable in liquids of lower pH. The freshly formed products are then stretched.  The chelate former is 8-oxyquinoline or one or more compounds of the general formula <FORM:0811115/IV (a)/1> wherein R and R1 each represent a substituted or non-substituted alkyl or aryl hydrocarbon radical or hydrogen, and may be either the same or different.  The compound of the above formula may be 5-mercapto-3-phenyl-2-thio-1,3,4-thio-diazolon-2 or a derivative thereof in which the phenyl radical is replaced by a halogen phenyl radical or a cyclohexyl or amyl radical.  The stretching of the shaped product may be effected by the one-bath or the twobath process.  The proportion of the chelate former in the viscose need only be very small, e.g. about 0.05 per cent or less based on the viscose.  The zinc sulphate concentration in the spinning bath is preferably at least 2-3 per cent.  The concentration by weight of sulphuric acid is preferably between 0.8 times and 1.3 times the alkali content of the viscose.  To enable higher spinning speeds to be used, the spinning may be carried out not only with the addition to the viscose of a chelate-former, as described above, but also in the presence of an anion- or cation-active or non-ionogenic surface-active agent such as a sulphonated fatty acid or fat which has a high content of organically bound sulphuric acid, as described in Specification 363,908, lauryl triethyl ammonium chloride or polyethylene oxide derivative.  These may be added to the viscose in proportions of 0.2-0.6, 0.2-0.75 and 0.1-1 per cent respectively, based on the cellulose in the viscose.  Alternatively, 20-100 mg. of lauryl pyridinium chloride may be added to each kilogram of coagulating bath.  In addition to or instead of using surface-active agents, the coagulating bath may be provided with tubes comprising sections of different diameter and arranged with their narrowest portion adjacent to the spinneret, through which the freshly spun threads are guided.  In an example, in the preparation of a viscose containing 7.3 per cent by weight of cellulose and 6.8 per cent of alkali, 0.1 per cent, calculated on the viscose, of 8-oxyquinoline is added to the alkali cellulose which is then xanthated with 36 per cent of carbon bisulphide.  The viscose is spun with a xanthate ratio of 0.48, a ripeness of 22 DEG  Hottenroth and a falling ball viscosity of 0.60 seconds into an aqueous spin bath containing 8 per cent of sulphuric acid, 19 per cent of sodium sulphate and 6 per cent of zinc sulphate.  The bath is at 70 DEG  C. and the filaments formed are stretched therein over a distance of 120 cm.  The filaments are then passed to a second bath at 90 DEG  C. consisting of the first spinbath diluted to 1.5 per cent sulphuric acid content.  In the other example, 0.12 per cent of 5-mercapto-3-p-bromo - phenyl - 2 - thio - 1,3,4 - thiodiazolon-2 and 0.3 per cent of a surface-active polyethylene oxide derivative are added to a viscose of 7.7 per cent cellulose and 5.5 per cent alkali content, and the viscose is spun as in the first example, except that the first bath is provided with guide tubes for the filaments.