Patent GB-244446-A (GB)
Title: Manufacture of flat ribbon-shaped artificial textile fibres from viscose
IPC: D01D5/247
Filed: 1925-11-24
Abstract: More or less hollow artificial textile fibres of a flat ribbon-shaped conformation are made by spinning viscose, to which has been added substances which produce or evolve gas, or in which a gas has been dissolved, under such conditions that in the preliminary coagulation no evolution of gas takes place although the filaments are still elastic and sufficiently strong to be wound, thereafter the evolution of gas which inflates the fibre is produced during the subsequent fixing of the filaments. Alternatively, the gas-producing substance may be incorporated in the filaments after spinning by treatment of the preliminarily-coagulated elastic filaments with a solution of the substance, for example, a solution of a carbonate.  The initial incomplete coagulation of the filaments may be secured by the p employment of a feebly-acting coagulation bath, or by removing the portions of the bath carried by the filaments by causing the latter to run over a suitable striking-off surface, or by neutralizing such acid by treatment with a bath of a carbonate, bicarbonate or other acid-binding substance, preferably a bath containing an ammonium salt.  The filaments coagulated in this manner are subsequently treated in a suitable fixing bath such as a strong acid solution, and in such bath the viscose &c. is completely decomposed and at the same time the decomposition of, or evolution of gas from, the substance producing gas takes place; in the case where a gas is dissolved in the viscose, evolution of the gas in the preliminarily coagulated filaments may be caused by heat or other means.  It is an advantage to add a small percentage of a zinc salt to the preliminary coagulation bath.  In examples, a viscose containing 5 per cent sodium carbonate is spun with a short spinning-trajectory in an acid sulphate bath, then treated with an ammonium chloride bath maintained alkaline by the addition of sodium carbonate, and immediately or after winding treated with an acid bath of low concentration.  A normal viscose is spun into an ammonium chloride bath, then passed through a sodium bicarbonate bath, and finally fixed in an acid sulphate bath.  Specifications 24291/14, 143,253 and 189,973 are referred to.  The Specification as open to inspection under Sect. 91 (3) (a) refers to the application of the process to other spinning solutions, for example, ammoniacal copper cellulose solutions, to the use of a preliminary coagulation bath maintained at a low temperature, to the employment of viscoses in which the proportion of carbonates, thiocarbonates, carbon disulphide &c., occurring therein, is increased by varying the method of manufacture, and to the use of a solution of a bicarbonate for adding the gas-yielding substance to the preliminary-coagulated fibres; and it includes an example in which an ammoniacal copper cellulose solution is spun in the usual manner, and immediately after spinning, the filaments are introduced into a solution of sodium bicarbonate, being afterwards fixed by treatment with dilute acid.  This subject-matter does not appear in the Specification as accepted.