Patent GB-760168-A (GB)
Title: Method of and apparatus for continuous production of synthetic fibres
IPC: D01D10/04
Filed: 1954-06-25
Abstract: In the continuous production of regenerated cellulose, the filaments from the spinneret pass into a first strongly acid bath where they are superficially decomposed, are drawn-off by a roller having independently regulable drive, intensely stretched (e.g. by 50-100 per cent) without the use of softening agents in a second bath by means of a second roller with independent <PICT:0760168/IV(a)/1> drive, then passed through a third bath of low acid content and completely regenerated, after which they are washed, dried and passed to a higher level for twisting and reeling.  The first bath preferably contains 40-70 per cent sulphuric acid at room temperature, the second 10-50 per cent sulphuric acid at about 50 DEG C., the third 2 per cent sulphuric acid at 70-95 DEG  C., although much lower concentrations at higher temperatures may be used, e.g. first bath 11-13 per cent sulphuric acid at 45-55 DEG  C., the second 0.2-4 per cent sulphuric acid at 50-95 DEG  C. and the third either the same as, or weaker than the second bath.  In each case known additions may be made to the acid baths, such as sodium sulphate and zinc sulphate, or equivalents such as magnesium and ammonium sulphates.  The completely regenerated threads pass on to crossed rollers whereon they are washed, this preferably being on the opposite side of the machine to avoid risk of contaminating the filaments with acid from the earlier baths. They are then passed up a tube down which flows a counter-current of conditioning air, to winding mechanism.  In the event of filament breakage, the counter current is switched-off, an air blast switched on to blow the filaments up the tube and a suction device at the top operated to receive them, all of which may be done automatically on filament breakage.  As shown, spinning solution from the supply pipe 1 passes through pump and filter 2 to spinneret 3 in the first acid bath 4, wherein the filaments are superficially regenerated from which they are drawn off by roller 6.  The filaments are then passed through acid bath 8 and drawn off by independently regulable roller 9 so as to impart a stretch of 50-100 per cent, and are then completely regenerated in the third bath, shown in Fig. 2 as in two parts 10 and 13 connected by a trough 12 down which the filaments pass together with treating liquid.  The third bath may be a single bath, or it may be in two parts connected by a trough 12 as shown or by a pipe whose inlet may be funnel-shaped and just below the level of the liquid in the upper portion of the bath.  The length of the trough or pipe 12 is adjusted so that the filaments, on emerging, are completely regenerated.  With this arrangement, in the event of filament breakage the ends are washed through, which facilitates rethreading, also the trough or pipe may be used to convey the filaments to the other side of the machine to the washing zone, clear of the acid-treating zone, and this may be assisted by injecting hot or cold water or steam into the pipe inlet.  The acid baths are preferably cowled and vapours exhausted therefrom by suction.  The filaments pass on to crossed rollers 15 whereon they are washed, to a reviving or dressing bath 16, to drying rollers 17 and up pipe 19 down which flows conditioning air introduced at 25.  The filaments pass through a breakage detector 23 to winding device 24.  In the event of filament breakage, device 23 causes the air current at 25 to be turned off and air blast at 18 to be turned on, whereby the filament ends are blown up pipe 22 and may be received in suction pipe 20, or wound at 24 with the aid of auxiliary movable injector 21.  It is stated that the division of the plant into three sections for spinning, washing and drying, and winding, enables any section to work independently.