Patent GB-1021537-A (GB)
Title: Method of producing viscose rayon staple and a spinning apparatus for use in the method
IPC: H02M7/44
Filed: 1964-02-25
Abstract: 1,021,537. Spinneret; viscose spinning. TEIJN Ltd. Feb. 25, 1964 [March 7, 1963; March 29, 1963 (2); April 6, 1963], No. 7864/64. Heading B5B. Regenerated cellulose fibres are made by extruding a viscose of gamma value at least 60 containing 4-7% by weight of cellulose component of a degree of polymerization at least 500 and 3-6% by weight of sodium hydroxide through a spinneret having at least 10,000 orifices at a spinning lineal speed not exceeding 10 m./min. into a spinning bath at a temperature not higher than 30 C. containing not more than 30 g/l. of sulphuric acid, at least 0À1 g/l. of anhydrous zinc sulphate and not more than 80 g/l. of anhydrous sodium sulphate, passing the thus extruded viscose through the bath until it becomes capable of withstanding being stretched with a draw ratio of 1À5 to 3À5, withdrawing the same from the bath, subjecting it to stretching with a draw ratio of 1À5 to 3À5 by means of a pair of rollers outside the bath, running the filament which has left the second roller until the degree of regeneration reaches 65-85%, and completing its regeneration in a hot aqueous bath. Preferably an annular spinneret is used, provided at about its centre with a channel provided substantially perpendicularly to the spinneret face, and the coagulating bath is let flow in the bath in substantially the same direction as that of the extrusion of the viscose,  to ¥ of the total amount of the flow of the coagulating liquid being passed through the said channel in the spinneret and the difference in the sulphuric acid content of the coagulating liquid continuously supplied to the bath and that continuously withdrawn from the bath being adjusted to 0À5-3À0 g/l., thereby the filament being coagulated in the bath until it becomes capable of withstanding being stretched with a draw ratio of 1À5 to 3À5. Preferred conditions comprise the use of a spinning bath containing 0À5-3À0 g/l. anhydrous zinc sulphate, running the filament which has left the second roller until its degree of regeneration reaches 65-75%, cutting the same into staple fibre and thereafter completing its regeneration, the ratio between tne peripheral speeds of the second roller and the collecting roller being from 100: 97 and 100: 110, and using a hot aqueous bath at 40-100 C. and containing 0À05-30 g/l. sulphuric acid and 0À1-4À0 g/l. anhydrous zinc sulphate. Apparatus as shown comprises an open spinning chamber 2 preferably of cylindrical form adapted to receive a coagulating liquid to a predetermined level, an annular spinneret 3 provided in the chamber at a position lower than the said level of the coagulating bath, said spinneret being provided at about its centre with a channel 32 substantially perpendicular to the spinneret face and with at least 10,000 orifices arranged substantially perpendicularly to the spinneret face around the channel, and further said orifices being connected (1) with the viscose-supply means, a means for regulating and distributing the flow of the coagulating liquid provided in the chamber at a position lower than the spinneret, said means having a large number of apertures 7 so arranged that they regulate the flow of the coagulating liquid and distribute it to the channel in the spinneret and around the spinneret at a predetermined ratio, and means to supply the coagulating liquid to the port of the spinning chamber lower than the said regulation and distribution means (4). An open cylinder, e.g. bounded by walls 2, 9 in Figs. 8, 10 and 11 (not shown) may be provided in the spinning chamber through which the as-extruded viscose may run together with the coagulating liquid, any of the distances between any point on the contacting line of the plane including the spinneret face with the inner wall of said cylinder and the orifice closest thereto not exceeding 10 cm. Additional means 8 for guiding and leading the flows of the coagulating liquid distributed by the said regulation and distribution means respectively into the channel in the spinneret and to around the spinneret may be provided. In Fig. 12 (not shown) the viscose and coagulating liquid are supplied from the upper part of the apparatus and an auxiliary flow regulation and distribution means 7 is provided as shown. As shown in Fig. 1, viscose from conduit 1 is spun through spinneret 3 in spinning chamber 2. Spinneret 3 has at least 10,000 orifices. The 10,000 or more filaments leaving 2 are guided by rollers 11, 11<SP>1</SP> and stretched between godet rollers 12 and 13 to a draw ratio of 1À5 to 3À5. The spinning lineal speed, i.e. the peripheral speed of roller 13, should not exceed 10 m./min. Filaments leaving roller 13 are passed outside the bath until their degree of regeneration reaches 65-85%. Suitably the ratio of the peripheral speed of the second godet roller 13 to that of the collecting roller 16 is from 100: 97 to 100: 110. At roller 16, several groups of filaments each of 10,000 filaments or more are collected to form tows of larger denier, having a degree of regeneration of 65-85%, and these are subjected to part-treating steps. In general, the tows are cut into staple fibres at cutter 17, their regeneration completed by the shower from the hot aqueous shower-trays 18 and 19 on a net conveyer 20, and they are washed with water and dried. Alternatively, cutting may be performed after regeneration is completed. Fig. 3 illustrates a suitable annular spinneret having at least 10,000 orifices, coagulating liquid being supplied through channel 32. Figs. 4, 5, 6, and 7 (not shown) show alternative spinnerets in which the 10,000 orifices are distributed over a plurality of unit spinnerets 31. The process enables high wet modulus fibres to be produced with high productivity and without any increase in abnormal fibre-formation frequency or degradation in product quality.