US2700794A - Wet-spinning cells - Google Patents

Description

Feb. 1, 1955 w. I. TAYLOR ET AL' WET-SPINNING CELLS Filed July 18, 1951 IN W? N T QS 6. G. HAM/TIN ATTORNEY United States Patent WET-SPINNING CELLS William Ivan Taylor and Selwyn George Hawtin, Spondon, near Derby, England, assignors to British Celanese Limited, a British company Application July 18, 1951, Serial No. 237,397 Claims priority, application Great Britain July 31, 1950 6 Claims. (Cl. 18-8) This invention relates to spinning cells for use in making artificial filaments and yarns by wet-spinning methods.

The invention consists in a novel type of spinning cell which is particularly adapted for upward wet-spinning using a volatile coagulating liquid; it also consists in the use of spinning cells of this new type, especially in the manufacture of filamentary material such for example as yarns, tow or bristles by wet-spinning an acetone solution of cellulose acetate into aqueous acetone as the coagulating liquid. The new cells are particularly suitable for making multi-filament yarns, that is yarns made up of a number of continuous filaments.

A spinning cell constructed in accordance with the invention comprises a spinning chamber containing one or more spinning jets, a vertical setting tube up which the extruded filaments and the coagulating liquid travel, and at the upper end of the setting tube a collector head for the coagulating liquid having a run-ofi for liquid leading therefrom and being completely or nearly completely closed against the outside atmosphere so as to provide a complete or nearly complete seal against the escape of vapour from the spinning cell into the atmosphere.

The collector head is advantageously a separate structural integer which can be fixed to the upper end of the setting tube to make a liquid-tight joint therewith, for instance by a quick release form of union. It may, however, be made in one piece with the setting tube.

The invention will be more particularly described in connection with spinning cells containing a single jet, in which the spinning chamber and setting tube are of circular cross-section. It includes however, spinning cells containing two or more jets, in which the spinning chamber and setting tube may have a non-circular cross section suited to the number and arrangement of the jets.

The spinning chamber and setting tube are preferably separate structures, arranged so that the tube can be attached simply and rapidly to the chamber to make a liquid-tight joint. For example, the tube may be attached to the chamber by means of a screw thread of high pitch having a length of 90 to 180. The spinning chamber is preferably of considerably greater cross-sectional area than the setting tube. At or near its lower end it is provided with one or more inlets for the coagulating liquid; at a somewhat higher level a spinning jet is mounted centrally in the chamber and facing upwards; between the level of the inlets for the coagulating liquid and the level of the jet face there may if desired be provided a horizontal perforated sheet, e. g. a gauze or the like, extending across the whole of the free space in the chamber, in order to reduce turbulence in the coagulating liquid.

As stated above, the spinning chamber is considerably wider than the setting tube taken as a whole. The transition from the wide to the relatively narrow parts of this cell is however preferably smooth so as to assist in maintaining a fairly smooth flow of the coagulating liquid up the cell. Thus the lower end of the setting tube may be frustro-conical in form; or a separate frustro-conical intermediate tube may be used, or the upper part of the spinning chamber may be frustro-conical.

The collector head has the function of collecting coagulating liquid after it has left the setting tube, and at the same time preventing or reducing to a low value losses by the escape into the atmosphere of the vapour of the coagulating liquid. It may take various forms.

2,700,794 Patented Feb. 1, 1955 One form, which has proved particularly useful when the filamentary material being spun is to pass directly from the collector head into the atmosphere, comprises essentially two co-axial tubular members of diiferent diameter which together form an annular chamber or passage closed top and bottom. The inner tubular mem her is preferably of about the same diameter as the setting tube, of which it is in effect a continuation. It may if desired be provided with holes through which the coagulating liquid can escape into the annular chamber, or the liquid may overflow at the top. The outer tubular member extends above the level at which the liquid escapes from the inner member. A run-01f for the liquid is provided at or near the bottom of the annular chamber, and between it and the level at which the liquid enters the chamber there is preferably fixed a filter element, by means of which small pieces of filamentary material and other solid contaminants can be removed from the coagulating liquid before it leaves the collector head and is returned to store or recirculated. The top of the collector head is closed or capable of being closed except for a small opening through which the filamentary material leaves the cell. For example, it may be fitted with a hinged lid provided with a slit for the passage of the filamentary material.

Spinning cells constructed in accordance with the invention and comprising a collector head of the general form described above are particularly well adapted for use in association with means for imparting a false twist to a multi-filament yarn formed therein, for instance by means of a skew pulley as described in United States application Ser. No. 217,816, filed March 27, 1951, of S. G. Hawtin and J. W. Grebby.

In a modification of the spinning cell described above, there is provided also a vertical or downwardly sloping tube in which the filamentary material may be subjected either to the further action of the coagulating liquid or to the action of a washing or aftertreating liquid, and which opens into the collector head, either at or near its base or else at a higher level, and preferably lies parallel to and close to or in contact with at least the upper part of the setting tube. This second tube will for convenience be referred to hereinafter and in the claims as a lateral tube. The opening at the lower end of the lateral tube is restricted in size so as to limit to a desired value the amount of liquid leaving the cell with the filamentary material through the lateral tube.

When a lateral tube is employed, the collector head may advantageously be somewhat different from that described above. Thus it may comprise a single chamber into the base of which the setting tube opens and which is provided with a run-off for coagulating liquid at a level substantially above its base, for example in the side wall. The collector head may contain guide means whereby filamentary material can be led from the setting tube through the collector head and into the lateral tube, and the escape of vapour into the atmosphere may be prevented by the provision of a dome-like cover or cap enclosing the guide means and making a substantially vapourtight joint with the remainder of the collector head.

The invention is illustrated in the accompanying drawings, in which Figure 1 is a side view in section showing one form of spinning cell embodying the invention,

Figure 2 is a side view in section showing the upper part of another form of spinning cell,

Figure 3 is a plan view of the upper end of the spinning cell illustrated in Figure 2 with the cover of the collector head removed.

The spinning cells illustrated are particularly well suited to the production of multi-filament yarn, and will be described in connection with this operation.

Referring now to Figure l, the spinning cell illustrated comprises a spinning chamber 11 having inlets 12 for the coagulating liquid and containing a spinning jet 13. Between the level of the inlets 3.2 and the upper surface of the jet 13 a perforated annular disc 14 may be provided to reduce turbulence in the coagulating liquid as it flows up through the spinning ice chamber 11. A setting tube 16, having at its lower end a frustro-conical section 15, extends vertically upwards from the spinning chamber 11, and carries at its upper end a collector head 17. The junctions between the lower end of the frustro-conical section 15 of the setting tube and the top of the spinning chamber 11, and between the collector head 17 and the top of the setting tube 16, are preferably of a quick-release fluid-tight type, for example the several components may be held together by screw threads of high pitch, and the abutting surfaces may bed on rubber or like material.

The collector head 17 comprises a lower section 18 and an upper section 19. The lower section 18 comprises an inner tube 23 which fits onto and serves as a continuation of the setting tube 16, and an outer wall 24 forming with the inner tube an annular passage or chamber open at the top and provided with a liquid run-off 25 in its base. Between the tube 23 and the wall 24 there is fixed a perforated annular plate 26 which serves as a support for filter material 27. A removable perforated cover plate 28 serves to hold the filter material in position. The upper section 19 is smaller in diameter than the lower section 18, and is provided at its lower end with a flange 20 fitting closely into the open upper end of the lower section 18. The flange 29 carries on its lower surface an annular projection 29, in which are formed a number of scallops 30, this projection 29 serves to space the flange 20 well above the cover plate 28. The upper end of the upper section 19 can be closed by a hinged lid (shown in its open position) containing a slit 22 for the passage of yarn from the cell.

In operation extruded filaments travel up the setting tube 16 and out through the slit 22 in the lid 21, preterably being brought together to form a yarn at a level below the top of the tube 23, for example by means of an adjustable skew pulley (not shown) as described in British Patent No. 695,559, situated some distance above the cell. At the same time the coagulating liquid travels up the setting tube 16 and the inner tube 23 of the collector head, until it overflows and runs down the outer Wall of the tube 23 to the cover plate 28. Here its progress is impeded by the filter material 27, and it spreads out over the cover plate 28 and through the scallops 30 in the projection 29, so that the whole area of the filter is used. After passing through the filter the liquid escapes through the run-01f 25. The flange 20 of the upper section 19 makes a tight fit against the outer wall 24 of the lower section 18, so allowing the escape of at most very small amounts of vapour from the liquid above the cover plate 28. The amount of vapour lost from the upper end of the collector head is kept low by the lid 21.

A diflerent form of cell, making use of a lateral tube as described in general terms above, is illustrated in Figures 2, 3 and 4. The spinning chamber (not shown) in this form of cell may be similar in structure to that described with reference to Figure l, and may be connected in the same way to a setting tube 16. The setting tube 16 carries a collector head 40 made in two sections, namely a body 41 and a cap 42 which fits on the body 41 to make a substantially vapour-tight joint. A liquid run-off 43 is provided in the side of the body 41 of the collector head, and a drain 44 leads from its base, by means of which all the liquid in the head 40 can be run off at the end of the operation. A lateral tube 45 which lies parallel to and close to the upper part of the setting tube 16 also opens into the base of the collector head, where it connects by a liquid-tight joint with a removable extension tube 46 provided with a tangential feed tube 47 for the supply of a treating liquid, and fitted with a supporting collar 48. The feed tube 47 passes out of the head through a closely fitting slot in the cap 42. When in position the extension tube 46 extends above the level of the rnn-ofi 43. At its lower end the lateral tube terminates in a spigot 49 having an orifice which will allow the desired rate of flow of liquid down and out of the tube. Below the spigot 49 a free-running pulley 50 is mounted in a bracket 51 fixed to the spigot 49 to serve as a yarn guide. Means (not shown) are also provided to collect liquid leaving the lateral tube through the spigot. A vertical support 52 provided with a slot 53 is mounted in the body 41 of the collector head, and extends into the cap 42. A block 54 containing a horizontal bore 55 is mounted on a bracket 56 capable of being moved along the slot and fixed in any desired position by means of a screw 57. One end of a. d .5

passes through the bore 55 and can be held in any desired position by a set screw 59. The other end of the rod 58 carries a fixed axle 60 at right angles to the rod, and a pulley 61 is mounted freely on the axle 69. A spinning cell of this kind can be operated either with or without the extension tube 46. When the lateral tube is employed to enable the yarn to remain in contact with a body of coagulating liquid over a distance greater than the length of the setting tube 16, the extension tube will not normally be used; coagulating liquid will then fiow from the collector head down the lateral tube at a rate depending on the size of the orifice in the spigot 49, and to some extent on the structure, size and rate of travel of the yarn. This rate should be less than the rate at which the coagulating liquid enters the collector head from the setting tube, so that the level of liquid in the head is kept constant at the level of the run-olf 43. If on the other hand the yarn is to be treated in the lateral tube with a liquid other than the coagulating liquid, e. g. a washing liquid, the extension tube 46 is employed to prevent coagulating liquid flowing into the lateral tube from the collector head, the desired treating liquid being introduced through the feed tube 47.

Yarn formed in the cell is guided directly into the lateral tube 45 or into the extension tube 46, as the case may be, by means of the pulley 61. When the extension tube 46 is being used, so that yarn being made in the cell can be treated in the lateral tube 45 with a liquid other than the coagulating liquid, the pulley 61 is fixed in a position above the open upper end of the extension tube 46 so as to lead the yarn, after it has left the coagulating liquid in the body 41 of the collector head, into the extension tube. The pulley 61 may if desired be fixed skew to the natural plane of the yarn as described in United States Application S. No. 217,816 by means of the set screw 59. When the extension tube is not used, so that part of the coagulating liquid in the body of the collector head travels down the lateral tube 45, it is convenient to have the pulley above the surface of the coagulating liquid in the collector head for threading up, and then to lower it so that the yarn remains immersed in the coagulating liquid during the whole or at Leas; the greater part of its passage through the collector Even if the cell is not provided with a lateral tube, it may comprise a collector head of the type illustrated in Figure 2, a slot or other small opening for the passage of the yarn out of the collector head being provided above the level of the run-otf 43, preferably in the side of the cap 42. The pulley 61 may if desired be held in a mounting, preferably a swivel mounting, at a fixed height in the head.

As already indicated, spinning cells made in accordance with the invention are intended for use in wet spinning processes in which the filamentary materials formed are coagulated while travelling substantially vertically upwards in a co-current stream of coagulating liquid. An example of such a process is the production of cellulose acetate yarn by extruding a solution of cellulose acetate in acetone into an upwardly flowing coagulating liquid which consists of aqueous acetone of concentration, for example, between about 40% and The spinning solution and the coagulating liquid may be at the same or different temperatures, either in the neighbourhood of room temperature or at a lower or higher level. It is one advantage of the new cells that the presence of the collector head greatly reduces loss of acetone by evaporation, and this advantage is of course also realised in other cases where the coagulating liquid is volatile at the temperature employed. The use of the new cells is, however, not restricted to such processes; for example. they may be used in the production of cellulose acetate yarns by extruding acetone solutions of cellulose acetate into aqueous solutions of diethylene glycol diacetate as described, for example in United States Patent No. 2,552.598 of P. F. C. Sowter and F. B. Hill.

Having described our invention, what We desire to secure by Letters Patent is:

1. Apparatus for the manufacture of filamentary ma.- terials by a wet-spinning process, which comprises a spinning chamber containing a stationary upward-facing s inning jet, a smooth-walled setting tube of smaller cross-section than the spinning chamber leading from the spinning chamber and extending vertically upwards above the spinning jet, a collector head into which the upper end of the setting tube opens, a second tube opening into and extending downwardly from the collector head and having a restricted orifice at its lower end, a liquid outlet from the collector head at a level above that of the open upper end of the setting tube, a yarn guide in the collector head, adapted to lead filamentary material from the setting tube to the second tube, movably mounted so that it may be fixed in positions lower or higher than the level of the liquid outlet, and a removable cover for the collector head whereby it may be substantially sealed against the atmosphere.

2. Apparatus for the manufacture of filamentary materials by a wet-spinning process, which comprises a spinning chamber containing a stationary upward-facing spinning jet, a smooth-walled setting tube of smaller cross-section than the spinning chamber leading from the spinning chamber and extending vertically upwards above the spinning jet, a collector head into which the upper end of the setting tube opens, a second tube, parallel and adjacent to at least the upper end of the setting tube, opening into and extending downwardly from the collector head and having a restricted orifice at its lower end, a liquid outlet from the collector head at a level above that of the open upper end of the setting tube, a yarn guide in the collector head, adapted to lead filamentary material from the setting tube to the second tube, movably mounted so that it may be fixed in positions lower or higher than the level of the liquid outlet, and a removable cover for the collector head whereby it may be substantially sealed against the atmosphere.

3. Apparatus for the manufacture of filamentary matcrials by a wet-spinning process, which comprises a spinning chamber containing a stationary upward-facing spinning jet, a smooth-walled setting tube of smaller cross-section than the spinning chamber leading from the spinning chamber and extending vertically upwards above the spinning jet, a collector head into which the upper end of the setting tube opens, a second tube opening into and extending downwardly from the collector head and having a restricted orifice at its lower end, a liquid outlet from the collector head at a level above that of the open upper end of the setting tube, a yarn guide in the collector head, adapted to lead filamentary material from the setting tube to the second tube, movably mounted so that it may be fixed in positions lower or higher than the level of the liquid outlet, a detachable extension tube provided with a tangential liquid feed tube and fitting over the open upper end of the second tube forming therewith a substantially liquid-tight joint and extending to a level above that of the liquid outlet but below the uppermost position of the movable yarn guide, and a removable cover for the collector head whereby it may be substantially sealed against the atmosphere.

4. Apparatus for the manufacture of filamentary materials by a wet-spinning process, which comprises a spinning chamber containing a stationary upward-facing spinning jet, a smooth-walled setting tube of smaller cross-section than the spinning chamber leading from the spinning chamber and extending vertically upwards above the spinning jet, a collector head into which the upper end of the setting tube opens, a second tube, parallel and adjacent to at least the upper end of the setting tube, opening into and extending downwardly from the collector head and having a restricted orifice at its lower end, a liquid outlet from the collector head at a level above that of the open upper end of the setting tube, a yarn guide in the collector head, adapted to lead filamentary material from the setting tube to the second tube, movably mounted so that it may be fixed in positions lower or higher than the level of the liquid outlet, a detachable extension tube provided with a tangential liquid feed tube and fitting over the open upper end of the second tube forming therewith a substantially liquid-tight joint and extending to a level above that of the liquid outlet but below the uppermost position of the movable yarn guide, and a removable cover for the collector head whereby it may be substantially sealed against the atmosphere.

5. Apparatus according to claim 2, wherein the guide means is a free-running pulley in a swivel mounting by means of which it can be set skew with respect to the natural plane of a yarn passing from the setting tube to the second tube.

6. Apparatus according to claim 4, wherein the guide means is a free-running pulley in a swivel mounting by means of which it can be set skew with respect to the natural plane of a yarn passing from the setting tube to the second tube.

References Cited in the file of this patent UNITED STATES PATENTS 827,434 Friedrich July 31, 1906 1,707,595 Berl Apr. 2, 1929 2,241,304 Heywood et al. May 6, 1941 2,243,116 Ostermann May 27, 1941 2,284,497 Torrence et a1. May 26, 1942 2,453,839 Furness Nov. 16, 1948 2,503,821 Hatfield Apr. 11, 1950

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