US2787021A - Wet spinning apparatus - Google Patents

Description

April 2, 1957 w. R. SCHMITZ WET SPINNING APPARATUS Filed Dec. 24. 1953 W m4 TM m m w M m 1 w M a ATTORNEY United States Patent G WET SPINNING APPARATUS William R. Schmitz, Larchmont, N. Y.

Application December 24, 1953, Serial No. 400,317

3 Claims. (Cl. 18-8) This invention relates to apparatus for treating fibers, yarns, threads, filaments and the like and more particularly it relates to apparatus for treating synthetic fibers in which there is a concurrent flow of the liquid bath as the fibers are passed through it.

In the spinning of rayon yarns, for example, a viscose spinning solution is extruded through minute orifices of a spinnerette into a coagulating or solidifying liquid bath. Thereby, a parallel series of continuous filaments are formed, which are subsequently converged into a tow and withdrawn from the bath after being suliiciently hardened. In the prior spinning apparatus, the stagnant liquid bath causes considerable drag on the moving filaments and in order not to break or over stretch them, the draw-off speed must be kept relatively low. Also to reduce friction, the distance the filaments are moved through the bath must be shortened. As a result a lower quality yarn is produced at a slower rate, than would otherwise be possible if the drag on the filaments were eliminated.

To overcome these difiiculties pumps and similar devices have been utilized to induce a concurrent fiow of the bath in the same direction as the moving filaments. However this practice has been found unsatisfactory for several reasons. For example, it requires the addition of numerous mechanical parts to the spinning machine, which in turn substantially increases the cost of construction. Also, it is difiicult and sometimes impossible to synchronize the speed of flow of the spinning bath with the speed of the thread. Furthermore, it greatly complicates the stringing up procedure.

Accordingly, it is an object of this invention to provide a simplified and inexpensive structure for treating fibers, threads, and the like wherein the drag on the fibers, as they are moved through a liquid bath, is substantially reduced.

Another object of this invention is to provide a structure of the above character which permits the filament to move a considerable distance through a treating bath without appreciably increasing frictional drag.

Another object of this invention is to provide a structure of the above character in which the speed of flow of the liquid bath is readily adjusted with respect to the speed of the moving filament.

These and other objects of this invention are attained by providing a baffie within the receptacle containing the coagulating bath and adjacent the path of the filaments, whereby the motion of the filaments induces a circulatory flow of the bath about the bafile. As a result, the direction and speed of the induced flow of the liquid bath is substantially the same as the direction of movement and the velocity of the filament, and thus the friction therebetween is substantially reduced.

For a better understanding of the present invention reference may be had to the accompanying drawings in which:

Fig. l is a schematic view in longitudinal section of a rayon spinning device constructed in accordance with the 'ice invention, showing the disposition of the baflle within the liquid bath.

Fig. 2 is a view in transverse section taken along line 22 of Fig. 1, looking in direction of the arrows.

With reference to Figures 1 and 2, a spinning machine schematically shown therein, includes a tank 10 having a bottom wall 11 and side walls 12 and 13, containing an acid spinning bath 14. An inlet chamber 15 (enclosed by an inclined partition 18 and the bottom 11 and side wall 13) communicates with. the interior of the tank through an inlet port 19 formed between a horizontally disposed end portion 20 of the partition 10 and the bottom tank wall 11. During the spinning operation, the bath 14 may be constantly replenished by maintaining a slightly greater hydrostatic pressure within the inlet chamber 15, than in the tank.

A bracket 21 mounted on the tank Wall 13, has a plate 22 formed integral therewith and inclined towards the opposite tank wall 12. As is best shown in Figure 2, the plate 22 carries a convergence guide 25 comprising a plate member 26 formed with a V shaped notch 27. The plate 22 also is formed with an inclined shelf 28 which extends downwardly and terminates adjacent the bottom 11 of thetank.

The tank 10 is formed with a separate spinning trough 30 by vertical partitions 31 and 32, which are secured to opposite sides 33 and 34 of the convergence guide support plate 22, and extend towards the left hand tank wall 12. The lower edges 35 of the partitions 31 and 32 are also secured to the inclined partition 18. A baffle 38 is mounted between the partitions 31 and 32, and is disposed in a parallel plane with respect to the shelf 28, forming therebetween a passageway 39. The upper or right hand end of the bafile 38 is spaced from the convergence guide plate 22, thereby forming opening 40 which communicates with passageway 39.

it will be understood that the tank 10 may be divided into a plurality of similar individual spinning troughs by mounting additional vertical partitions and baffles in the manner described above.

A goose neck 44 is pivotally connected at one end to the left-hand tank wall 12 by means of an apron block 45. The opposite end of the goose neck 44 extends into the bath 14, and is provided with a cylindrically shaped spinnerette 46. In the viscose spinning process subsequently to be described, a viscose solution is extruded through minute orifices in the spinnerette 46, into the acid spinning bath 14. As the extruded solution comes in contact with the bath, it is solidified and hardened, thereby forming a series of filaments (a strand) indicated at 47.

Thereafter, thestrand 47 is combined into a rope or tow 48, as it is drawn through the V-shaped notch 27 in the convergence guide 25. The tow 48 is then directed under a hold-down type guide 49 and a stripper guide 50, to a direction-changing roller 51 which is mounted on the right-hand tank wall 13. It will be noted that the tow 48 does not emerge from the bath 14 until it passes between the guides 49 and 50. Also it will be seen in Figure 1, that the strand 47 moves in a plane generally parallel to the baflle 38.

As the strand 47 is moved towards the convergence guide 25, its movement is utilized to induce a concurrent, circulatory flow of the bath 14, about the bafiie 38, as indicated by the arrows. Thus, a few moments after the spinning operation is commenced, the induced flow of the bath increases to a point where it nearly equals the speed and direction of the moving strand 47, and as a result the friction created therebetween is substantially reduced. Also in this connection, it will be seen that the direction of flow of the bath 14 through the inlet port 19, as indicated by the arrows, is approximately the same as the induced flow about the baffle 38, and this may be utilized to increase the velocity of the latter and afford more uniform mixing of the incoming solution with the treating solution.

To better understand the important advantages of this invention, it will be appreciated that the best quality yarn is produced under conditions where the filament at the time of formation is relatively weak, the filament is immersed in the bath for a relatively long period of time, and where the filament is not subjected to an undue amount of stretching before it has been thoroughly solidified by the acid bath. To further clarify the firstmentioned condition, there is an optimum acid bath concentration which will produce a final filament of maximum strength, however, it is characteristic that at this optimum acid bath concentration the strength of the newly formed filament is relatively weak. Although higher acid concentrations will cause the initially formed filament to be stronger, the ultimate filament is unfortunately weaker. In the prior spinning devices these optimum conditions cannot be attained because the friction created by moving the filaments through a stagnant bath causes excessive stretching of the filaments. As a result, the outer surfaces of the filaments become highly oriented before their cores are susceptible to orientation. Thereafter, when the cores become solidified and are then oriented by further stretching, the outer surfaces of the filaments are ruptured. The filaments formed in this manner have a low tenacity in comparison with filaments in which the cores and outer surfaces are stretched and oriented, simultaneously.

By utilizing spinning apparatus of the type described above, it will be appreciated that it is possible to spin rayon filaments at a greater rate of speed, and to move them a greater distance through the bath without materially increasing the frictional drag. Also, an initially weaker filament acid spinning solution may be used because the filaments remain in contact therewith, for a longer period of time. As a result, it is possible to produce better quality yarn at a greater rate of speed. Furthermore, this new spinning apparatus makes it possible to spin rayon yarn under conditions where the fila ments coagulate so slowly, or are so weak in the region of formation, that spinning in a stagnant bath would be impossible at any commercial speed.

It is to be understood that the form of the invention described above is susceptible to considerable modification, and may be used in conjunction with other types of filament-treating apparatus. Accordingly,- the form of the invention disclosed herein should be considered as illustrative and not as limiting the scope of the following claims.

I claim:

' 1. In an apparatus for treating filaments in a fluid bath, a receptacle for a coagulating fluid bath, means including a spinneret disposed within said receptacle for continuously extruding viscose filaments into the bath, guide means disposed above and at a distance from the spinneret forguiding the filaments through said receptacle in an upwardly inclined path, an upwardly inclined bafile mounted within the receptacle below the path of travel of the filaments through the receptacle, the upper end of said bafile being submerged below the upper level of the bath, the movement of the filaments through the bath inducing an upward flow of said fluid above the battle, means forming a downwardly sloped surface beneath and spaced apart from the underside of said baflle, said underside of said bafile and said downwardly sloped surface forming a passage therebetween for the return flow of said fluid, and means forming a guiding surface extending upwardly from the downwardly sloped surface, but spaced apart from the upper end of the battle, for deflecting the fluid around the upper end of the baflle and into the return passage beneath the baffle, whereby a continuous flow of the fluid is maintained around said balfle.

2. An apparatus as set forth in claim 1 including an inlet port disposed beneath the lower end of the down wardly sloped surface to replenish the fluid in the receptacle and to feed said fluid approximately in the direction of the return flow of the fluid toward the base of the baflie.

3, In an apparatus for treating filaments in a fluid bath, a receptacle for a coagulating fluid bath, means including a spinneret disposed within said receptacle for continuously extruding viscose filaments into the bath, guide means disposed above and at a distance from the spinneret V for guiding the filaments through said receptacle in an upwardly inclined path, a pair of upright walls spaced apart within the receptacle, thereby forming a channel through which the filaments are guided in their passage through the receptacle, an upwardly inclined baflle plate mounted between the pair of upright walls and below the path of travel of the filaments through the receptacle, the upper end of said baffle plate being submerged below the upper level of the bath, whereby the passage of the filaments through said channel induces an upward flow of said fluid through said channel and above the baffle plate, means intermediate said pair of upright walls forming a downwardly sloped surface beneath and spaced apart from and substantially parallel to said baflle plate, said baffle plate and said downwardly sloped surface forming a passage therebetween for the return flow of said fluid in a direction opposite to the flow of the fluid above the bafiie plate, and means extending upwardly from the downwardly sloped surface forming a guide surface for deflecting the fluid around the upper end of the bafile plate and into the return passage, whereby a continuous flow of the fluid is maintained around said bafile plate.

References Cited in the file of this patent UNITED STATES PATENTS 2,659,102 Rarick Nov. 17, 1953

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