US2849751A

US2849751A - Wet-spinning apparatus

Info

Publication number: US2849751A
Application number: US536479A
Authority: US
Inventors: Sonnino Mario
Original assignee: American Cyanamid Co
Current assignee: Wyeth Holdings LLC
Priority date: 1955-09-26
Filing date: 1955-09-26
Publication date: 1958-09-02
Anticipated expiration: 1975-09-02
Also published as: GB817814A

Description

Sept. 2, 1958 M. SONNINO 2,349,751

WET-SPINNING APPARATUS Filed Sept. 26. 1955 2 Sheets-Sheet 1 INVENTOR. MAR/0 .SONN/MO,

ATTORNEY.

Sept. 2, 1958 Filed Sept. 26, 1955 M. SONNINO WET-SPINNING APPARATUS 2 Sheets-Sheet 2 I I l I 'l II IN V EN TOR.

MAR/0 SON/VINO,

ATTORNE).

United Stats WET-SPINNING APPARATUS Mario Sonnino, Stamford, Conn., assignor to American Cfyla rllamid Company, New York, N. Y., a corporation ame Application September 26, 1955, Serial No. 536,479

Claims. (Cl. 188) may be either homopolymeric acrylonitrile or a copolymer of acrylonitrile containing a major proportion by weight of acrylonitrile combined in the polymer molecule.

Various methods of producing synthetic or artificial fibers in continuous filament, tow and staple form heretofore have been suggested or are in use, and involve the use of appartaus of various designs. In general, such methods involve the production of filaments by either the so-called dry-spinning or wet-spinning methods. The present invention is concerned with apparatus whereby synthetic filamentary material in the form of continuous filaments (monoor inultifilaments) or tow (rope or bundle of continuous filaments) is produced by a wetspinning operation. The invention will be described with particular reference to the production of synthetic filaments of a polymer of acrylonitrile but is obviously not limited to the preparation of filamentary material only from such a polymer. For instance, it can be used in making filaments from regenerated cellulose (rayon) or from any other compositions that can be formed into filaments by extrusion through a spinneret into a suitable liquid coagulant.

In the wet-spinning method of producing filamentary material, e. g., polyacrylonitrile yarn or tow, a solution of the polyacrylonitrile is extruded through a perforated nozzle or jet, which is commonly known as a spinneret, into a bath composed of a liquid that will leach out the solvent from the polymer solution. As a result of thus extracting the solvent from the solution, the polymer is coagulated or precipitated from the solution. The coagulated yarn or filamentary material forms at the face of the spinneret and is carried through the bath for a sufficient distance and at a rate such as will cause solidification of the coagulated filamentary polymer to the desired extent. Thereafter the coagulated yarn is generally subjected to a stretching operation, usually while it is still in a gel state, in order to increase the tenacity as well as otherwise to improve the physical properties of the filaments. This improvement in properties results from orientation, along the fiber axis, of the polymer molecules of which the filaments are comprised. Other treating and processing steps then may be given the oriented filaments, such as, for example, washing, crimping, cutting into staple lengths (either before or after drying), etc.

It is a primary object of the present invention to provide wet-spinning apparatus, which includes the filamentforming portionthereof, and which is compact in its layout or arrangement and provides ready accessibility to the various elements thereof, from the operating face of the apparatus, for thread-up, inspection, jet maintenance, etc.

2,849,751 Patented Sept. 2, 1958 ice Another object of the invention is to provide apparatus of the kind briefly described in the previous paragraph that is relatively simple and inexpense to construct and which can be operated with a minimum number of operators.

Another object of the invention is to provide wet-spinning apparatus that will provide maximum yield of prodnot at minimum capital expenditure and utilizing a minimum of floor space.

A further object of the invention is to provide apparatus of the character described hereinbefore that will provide maximum yield of product at minimum cost from the standpoint of both maintenance and labor expenditures.

Still other objects of the invention will be apparent to those skilled in the art from the description which follows and the accompanying drawing.

The novel features of my invention are set forth in the appended claims. The invention itself, however, will best be understood from reference to the following more detailed description when considered in connection with the accompanying drawing, which is illustrative of a preferred embodiment of the invention, and wherein:

Fig. 1 is a plan view of wet-spinning apparatus embodying my invention;

Fig. 2 is a perspective view of a portion of the apparatus shown in Fig. 1; and

Fig. 3 is a side view of a portion of the apparatus shown in Figs. 1 and 2, more particularly the filament-forming assembly thereof in both its normal operating or spinning position and in its bleeding or dripping position.

Referring to the drawing there is shown in Figs. 1 and 2 wet-spinning apparatus for use in producing synthetic filamentary material comprising a container 10 for confining a liquid coagulant 12 (Fig. 3) therein. This liquid coagulant (taking the process described in Cresswell U. S. Patent No. 2,558,730, dated July 3, 1951, as illustrative of a wet-spinning process by which continuous filamentary material can be produced from a spinning solution or dope, e. g., a solution of a polymer of acrylonitrile) advantageously may be water alone or an aqueous solution containing from 5 to 15% of a water-soluble thiocyanate such as sodium thiocyanate, and which is maintained at a temperature not exceeding +10 C., e. g., about 0 C. The container 10 advantageously may be formed of a synthetic material, e. g., unplasticized polyvinyl chloride, or of a laminate comprised of a combination of a polyester resin and glass fibers in fabric or other form. This container has a bottom wall 14 which is so sloped that when theapparatus is in use there is a greater depth of liquid coagulant in the filament-forming endsection 16 of the container than at the opposite end 18 where the coagulated filamentary material 20 leaves the container. In addition to the bottom wall 14, the container 10 also is provided with

end walls

22, 22a, etc. (Figs. 1 and 2) and with parallel or approximately parallel side walls 24 and 25 (Fig. 1). When viewed in plan, the container has the general configuration of a trapezoid.

The liquid coagulant 12 is introduced into the endsection 16 of the container 10 by suitable means which include appropriate pumps (not shown) and a compartment 26 having openings 28 (Fig. 1), 28a (Fig. 2), etc., in its upper or top wall 30. This upper wall 30 of the compartment 26 constitutes a portion of the bottom wall M of the container 10. The liquid coagulant 12 is introduced into the compartment 26 through a suitable inlet conduit or conduits, e. g., inlet conduit 32 (Fig. 2) from a suitable supply source (not shown).

The

openings

28, 28a, etc., may be reduced in size when it is desired to restrict the volume of inflow of liquid coagulant to the container, or to a particular unit thereof, merely by closing off a portion of the opening with a suitable plug or insert.

It is a particular advantage of my invention that, by means of thecompartment and auxiliary parts embodied in the apparatus, turbulent flow of coagulant in the area adjacent 'to the spinneret face is obviated or -minimized, thereby facilitatingthe formation of uniform, undamaged, gelled filaments.

When a plurality of filament-forming

assemblies

34, 34a, 34b, 340, as shown in Figs. 1 and 2, is employed inproducing a rope orbundle of filaments (that is, tow) then the compartment 26 is a manifold compartment or chamber having a plurality of

openings

28, 28a, etc., corresponding in number to the number of filamentforming assemblies. These openings are so located that each is closely adjacent to a single filament-forming assembly. By this construction and arrangement of the openings or orifices the flow of liquid coagulant to each filament-forming assembly, and more particularly to the spinneret thereof, is uniform. By thus maintaining a uniform flow of the liquid coagulant to the area adjacent the face of each spinneret of the filament-forming assemblies better assurance is provided that the coagulated filaments as they form at the face of the spinneret will be uniform in size and in degree of coagulation.

In the preferred embodiment of the invention the container ltl is provided with partitions or

baffles

36, 36a, 3612, which are parallel or approximately parallel to the side walls 2'4 and 25 of the container and whereby the liquid coagulant serving one filament-forming unit is preventedfrom inter mingling with that which serves each adjacent unit. The advantages of having such partitions disposed in the container in order to separate each filament-forming assembly and coagulated tow are practical advantages that will be immediately apparent to those skilled in the art. These bafiles may be formed of any suitable construction material, which is not affected by, nor will affect, the liquidcoagulant, e. g., unplasticized polyvinyl chloride, Teflon, stainless steel, aluminum, etc.

In the preferred embodiment of the invention the bottom wall 14 begins an upward and rearward slope from the front edge 38 as shown in Figs. 1 and 2. It is not essential that the bottom wall begin to slope upwardly from this front edge and, if desired, the slope may begin at any other point which is closer to the end wall 22 (Figs. 1 and 2), 22a (Fig. 2), etc., or somewhat closer to the rear edge 40'of the bottom wall 14. From the standpoint of simplicity and minimum cost of construction the bottom wall 14 advantageously may begin to slope upward from the front edge 38 as indicated. This edge '38 is in the same plane as the vertical side wall 42 'of the compartment 26.

By having the bottom wall slope upwardly toward the rear "or discharge end of the container, the volume of the liquid coagulant in the container is substantially reduced, with important practical advantages. For example, this construction substantially reduces the volume of liquid coagulant to be recirculated in the process, as well as the volume of'ma'ke-up coagulant to be added to the system. Also, when the process employed is of the type or kind described in the aforementioned Cresswell patent and wherein the liquid coagulant is refrigerated to maintain it at a low temperature, then the re frigeration requirements also are materially reduced, because thereis a lesser total volume of coagulant to be refrigerated.

Another very important advantage of the use of the described-sloping bottom is that the coagulating solution flows concurrent with the rope or tow of filamentary material; hence, since the rate of flow of liquid coagulant to the container is substantially constant, the solution increases in its velocity as it approaches the overflow point from the container and at which point the filamentary material is the strongest. It is well-known that freshly coagulated filamentary material is weakest at the face of the spinneret where it is first formed and that it gets stronger as it leaves the face of the spinneret. By the arrangement hereinbefore described and illustrated in the accompanying drawing, the tow, as it becomes increasingly stronger, is subjected to an increasingly greater action by the liquid coagulant (due to its aforementioned higher velocity) as they both approach the discharge end of the container. Also, the higher-velocity coagulant provides a better support for the tow. The gelled tow has sufiicient tensile strength when it leaves the coagulating bath that it can be further handled and processed in gel state without any particular difficulty.

The filament-forming

assemblies

34, 34a, 34b, 340 are each comprised of a spinneret head 44 and a spinneret having a face indicated at 46 in Figs. 1 and 3. The spinneret is detachably mounted in the spinneret head 44 and is so positioned in the container that the coagula'ted filamentary material leaving the face of the spinneret is approximately parallel to the walls defining the sides of the container.

The individual filament-forming

assemblies

34, 34a, 34b, 340 are each so pivotally mounted and the spinneret so mounted in the spinneret head 44 that the assembly can be swung outside of the container from a spinning to a bleeding or dripping position as shown in Fig. 3, while the spinneret remains in the same plane. In Fig. 3 the spinneret is shown at A in the normal position in which it is employed during the spinning operation and at B in the position to which it is swung outsideo'f the container when it is in a bleeding position.

The spinning solution is led to the individual filamentforming assembly by suitable means which preferably comprise, as shown in Fig. 2, a conduit 43, a hollow trunnion 5d and a conduit 52 leading from this trunnion into the spinneret head 44. En route to the trunnion 55 the spinning solution passes, if desired or required, through a heat exchanger 54, wherein the solution is heated to the desired temperature by a suitable 'fiuid medium such as steam, hot water, oil, etc. The hot fluid medium enters the heat exchanger 554 through the inlet conduit 56 and is dischargedfrom the exchanger through the outlet conduit 58. When it is desired to move the spinneret head 44 from a point within the container to a point outside the container or vice versa, this isdo'ne by merely swinging the head about the axis of the trunnion 59 as shown in Fig. 3.

When it is desired to place the head 44 in a bleeding position, the bleedings or drippings from the spinnert of an individual filament-forming assembly 34 are caught in the trough 60, which is provided with a bottom that slopes toward the outlet 62 (Fig. l) and thence through conduit 64 (Fig. 3) to a recovery system (not shown).

I prefer to use as the filament-forming assembly the device disclosed and claimed in the copending application of William N. Sellers and Mario Sonnino, Serial No. 536,700, filed concurrently herewith, and which has a filter unit embodied in the spinneret head. If a different device containing no such filter unit is used, then it is generally preferable to filter the spinning solution before it enters the heat exchanger 54. This filter may be, for example, a candle filter that is positioned either before or after the pump or pumps that pump the spinning solution to the filament-forming assembly.

The liquid coagulant overflowing from the container 10 at the rear edge 4th first passes through a porous trough 66 (Fig. 2) and thence into the trough 68. T he porous trough 66 may be formed of any suitable material, such as wire screening, and in which any broken filaments or other filamentary waste material can be collected before the liquid coagulant passes into the trough 68. The trough 68 is provided with suitable conduits, one of which is shown at '70 in Fig. 2, for withdrawing the liquid coagulant from the wet-spinning apparatus for recirculation in the system, generally with the addition of a certain amount of make-up solution so that it will be of the same desired composition when it is re-used in the process.

The apparatus of this invention also includes an apron 72 which is spaced from the rear edge 40. On this apron 72 are mounted the

capstans

74, 74a, 74b, 740. If only a single filament-forming unit is to be used, then only a single capstan is required. The apron 72 slopes toward the trough 68 as indicated in Fig. 2. The capstan or capstans mounted on the apron serve to guide the coagulated filamentary material away from each of the filament-forming units of the wet-spinning apparatus.

A particular advantage of the construction of the wetspinning apparatus of this invention is that not only the filament-forming

assemblies

34, 34a, 34b, 340, etc., are accessible from the operating face 76 (Fig. 1) of the apparatus but the

aforesaid capstans

74, 74a, 74b, 740

are also accessible from this operating face. This is because of the size and arrangement of the apparatus as a whole, including the manner in which the end walls of the container are offset from each other as shown in Figs. 1 and 2, and more clearly in Fig. 2 where the

end walls

22 and 22a are offset. These

end walls

22 and 22a abut the wall 78 which forms all or part of one side of the filament-forming end-section 16. The same general relationship exists between the other filamentforming units of the apparatus if there are more than 2 units, e. g., from 3 to 50.

I claim:

1. Wet-spinning apparatus adapted for use in producing synthetic filamentary material comprising a container capable of confining a liquid coagulant therein, said container having a bottom wall that slopes upwardly from the front portion of the container to the rear portion; a plurality of pivotally-mounted, filament-forming assemblies each comprising a spinneret head and a spinneret detachably mounted therein, said assemblies being positioned during spinning at the front portion of the container and with the spinneret so mounted in the spinneret head that the coagulated filamentary material leaving the face of the spinneret is approximately parallel to the walls defining the sides of the container, the individual assembly being adapted to be swung outside of said container from a spinning to a bleeding position while the spinneret face remains in the same vertical plane; an operating face comprised of a series of end walls and side walls defining the said front portion of the said container, the said end walls being olfset from each other in a stepwise manner for a distance such that when the individual filament-forming assembly is swung out of the container and over the side wall that abuts the said next end wall it will be extrenal to the latter; means for charging spinning solution to the spinneret heads of the individual filament-forming assemblies; means for collecting waste spinning solution outside the said container when an individual filamentforming assembly is in a bleeding position; means for introducing liquid coagulant to the said front portion of the said container through a plurality of openings corresponding in number to the number of filament-forming assemblies and each opening being located closely adjecent to a single filament-forming assembly, each opening being so positioned with respect to the said assembly that a vertical line drawn through the edge of the said opening that is furthest from the vertical front wall of the front portion of the said container is rearward of a vertical line drawn through the face of the spinneret mounted in said assembly when it is in operating posi-.

tion; and means for removing the liquid coagulant from the said container at the said rear portion.

2. Wet-spinning apparatus as in claim 1 wherein the means for introducing liquid coagulant to the defined front portion of the container includes a manifold compartment positioned beneath the filament-forming assemblies, said compartment having an upper wall with a plurality of openings therein corresponding in number to the number of filament-forming assemblies and each opening being located as is set forth in claim 1.

3. Wet-spinning apparatus as in claim 1 wherein the means for removing the liquid coagulant from the container at the defined rear portion thereof are overflow means, and the apparatus additionally includes a trough beneath the rear edge of the container for receiving the overflowing liquid coagulant; an apron spaced from said rear edge and sloping toward said trough; and a plurality of capstans mounted on said apron for guiding the coagulated filamentary material away from each of the filament-forming units of the said wet-spinning apparatus, the said capstans being accessible from the said operating face.

4. Wet-spinning apparatus as in claim 1 wherein the means for collecting Waste spinning solution'outside the container when the individual filament-forming assembly is in a bleeding position includes a plurality of individual troughs located external to the container, each trough excepting the last being mounted on the off-set end walls of the container with its plurality of corresponding filament-forming assemblies therein, and the location of the individual trough on said end walls being such that it can receive the bleedings of the immediately preceding filament-forming assembly when the latter is in a bleeding position.

5. Wet-spinning apparatus as in claim 1 wherein the container has partitions therein which are approximately parallel to the side Walls of the container and whereby the liquid coagulant serving one filament-forming unit is prevented from intermingling with that which serves each adjacent unit.

References Cited in the file of this patent UNITED STATES PATENTS 1,425,368 Clayton Aug. 8, 1922 2,210,116 Dryfus Aug. 6, 1940 2,570,172 Kohorn Oct. 2, 1951 2,659,102 Rarick Nov. 17, 1953 2,696,637 McDermott Dec.- 14, 1954 2,787,021 Schmitz Apr. 2, 1957 FOREIGN PATENTS 662,294 France Aug. 5, 1929 777,209 France Feb. 14, 1935 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,84%751 September 2 1958 Mario Sonnino It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 3, for "inexpense" read an; inexpensive column 4, line 49, for "spinnert" read spinneret column 5 line 28, for "2 units" read 2 such units line 52, for "extrenal" read external 0 Signed and sealed this 3rd day of February 1959,

'SEAL) \ttest:

CARL Ho AXLINE ROBERT C. WATSON Lttesting Officer Commissioner of Patents