US2370765A - Spinnerette - Google Patents

Description

F. c. ATWOOD SPINNERETTE March 6, 19 45;

' Filed Aug. 15, 1959 INVENTOR Funalr lkgh fllwod A T'ro Nils was M". c, 1945' UNITED s'rArr-zs PATENT orncr.

7 SPINNERETTE Francis Clarke Atwood, Newton, Mara, aulgnor,

by mesne assignments, to National Dairy Products Corporation, New York, N. Y., a corpora tlon of Delaware Application August 15, 1939, Serial No. 290,158

5 Ulaims.

This invention relates to splnnerettes and, more particularly, to an improved form of spinnerette to be used in the simultaneous production of a relatively largenumber ofartificial fibers or filaments from protein, cellulosic or other solutions. The spinnerette is primarily adapted for use in a process in which the spinnerette is'immersed in a coagulating bath and the fiber or filaments are extruded. directlyin and through said bath.

It has been found'that the spinnerettes as heretoforemade are unsatisfactory for the formation of a, large number of fibers or filaments in a continuous operation. This is due primarily to the fact that the prior art spinnerettes, which for the most part have flat or spherical surfaces, are incapable of being increased in size without greatly decreasing their strength and emciency in operation.

As indicative of the probleminvolved, the perforated portion of the nozzle must be formed out of a very thin material in order to facilitate the punching or boring of holes in said material. Thus, if the spinnerettes in the shapes previously known are made larger so as to be capable of producing simultaneously a larger number of fibers or filaments, it'has been found that the material namely, placing the holes closer in a splnnerette of a shape heretofore used, it is found that great difliculty is encountered in properly coagulating the fibers. 'I'he bath does not come into contact sufliciently with the fibers with the result that they frequently runtogether and the'final prod- 7 not is not uniform. This is particularly true in the art of spinning synthetic protein fibers'from casein inasmuch as the extruded fibers coagulate at a relatively slow rate.

If the second mentioned expedient is followed. namely, increasing the thickness of the perforated portion ofthe nozzle. the cost-of forming the holes is increased. I have found thatthe relationship" between the thickness of the spinnerette head and greater than two to one. if the holes are to be formed expeditiously by punching. Thus, since the diameter or the orifices is one of the iactors determining the size oi the final product, which is I preferably as small as possible, and since I More specifically, it is an object or my inveni thickness of the spinnerette head is dependent on the diameter of the orifices, it is apparent that a thick material for the spinnerette head can not be employed vwhen the desirable small diameter fibers are to be manufactured. This is another limitation which rendered the prior art spinnerettes unsuitable for producing a large number of fibers simultaneously, particularly when the product desired was of a relatively fine nature. It

39 would be impossible to enlarge the prior art spinnerettes so that they would be capable of producing the large number of fibers without, at the same time, so increasing the thickness of the perforatecl portion of the nozzle that they would be 7 s unsuitable for extruding relatively fine fibers.

, The adoption of the third expedient, namely,

using a largenumber of spinnerettes, is expensive, space consuming, and is particularly dis-f advantageous in that it results in a' lack of uni- 2o formity of the fibers.

Furthermore, it has been found that in spinnerettes of the shapes heretofore made, other than planar, the boring or punching of holes is a difiicult and costly procedure, due to the fact 5,, that the holes have been bored or punched after the nozzle has been made into its spherical or other shape.

Accordingly, an object of my invention is to provide a spinnerette having very small holes for 30 extruding simultaneously an unlimited number or filaments, for example, of the order ofas high as 8,000 to 10,000 or more, and which is capable of withstanding the usual fluid pressure applied thereto.

5 An additional object ofmy invention is to provide a spinnerette of such form and shape as to permit. a more close spacing of the holes without interferingwith the proper manufacture of the fibers.

40 A further object of the invention is to provide a spinnerette having any desired large number of apertures, in which-said apertures are sumciently v spaced-.so that substantially all the fiber or filaments extruded therefrom will come into sufiicient 46 and substantially equal contact'with the coagulatthe diameter or the orifices is, preferably not I0 filaments in such a manner that any broken or strayfi'lbers will be carried along by the other fibers and thus not accumulate in the bath and gibtzrfere with or impede the withdrawal of the large strand.

spinnerette having the desirable characteristics described above and which is relatively inexpensive and easy to manufacture.

Additional objects of the invention will be apparent from the following detailed description taken in connection with the accompanying drawing, in which:

Figure 1 is a front view, partly in cross section, of the spinning apparatus in assembled position;

Figure 2 is a plan view of part ofFigure 1;

Figure 3 is a view in perspective of one form of the spinnerette head;

Figure 4 is a sectional view of the spinnerette head shown in Figure 3; and I Figure 5 is an enlarged cross sectional view of the spinnerette shown inFigure 1 Referring to the drawing, the spinnerette is adapted to be used in a process and apparatus in which the spinning solution orvehicle is conveyed through apipe I from any suitable supply source (not shown in the drawing) and forced under pressure byhmeans of any suitable pumping device 2 through a pipe 3 to the spinnerette 5. The pipe 3 is formed with a variable joint 4 whereby the position and angle of the spinnerette 5 may be regulated within the tub H. The neck 1 of the pipe 3 is attached to the distributor head 8 of the spinnerette by any suitable means such v as by a screw thread as indicated at 6. The extruded filaments l6 are drawn by the withdrawing roller l'l through the coagulating bath i5 over the rod 2L, The roller l1 may be power driven at a desired speed by means of pulley Ha. The roller I! may be of the type shown in Figure 2 whereby the filaments are gathered together in a In Figure 5, which is an enlarged view of a spinnerette similar to that shown in Figure 1, the

spinnerette head 9, with radial holes i0 therein, is secured to the distributor head 8 by means of frame l2 and bolts 13. This may be accomplished, for.example, by welding the longitudinal edges of spinnerette head 9 to form flanges II, which are securely engaged between frame l2 and distributor head 8. In the drawing the size of holes is greatly enlarged for illustration, and in practice they are about to microns in diameter.

The distributor head '8 as illustrated in Figure 5 is formed with a recessed portion 8a. This construction has the advantage of providing a larger volume within thespinnerette and facilitates the equalization of the pressure in the fluid being extruded, a factor which is significant as will be seen from subsequent discussions. The recessed portion also makes it possible to employ a screen 9a which is secured between the distributor head 8 and the flanges ll of the spinnerette head.

' This screen is effective for filtering out any foreign material or solid objects that may possibly be present in the spinning solution and obstruct the-holes in the spinnerette or causes weak points in the fiber. In general a screen having a mesh size less than the size of the opening in the spinnerette head is employed. For example, anopening in the spinnerette having 'a diameter of 100 microns would correspond to a screen having meshes to the inch. Since these meshes are more or less rectangular, it is desirable to use a screen in which the diagonal of the screen opening is less than 100 microns. It is desirable, therefore to employ a screen having about a 200 mesh for use with a spinnerette having openings of 100 microns in diameter. Such a screen would remove from the solution any material that is likely to clog the holes of the spinnerette. The screen also assists in the equalization of the pressure of the spinning solution. Such screens have the advantage of eliminating the so-called candle" filter which is normallyemployed in the rayon industry and located in the ipe line leading from the pump of the spinnerette.

In Figure 4, a modification of the screen is" illustrated in which the screen surface 91) is curved so as to have a shape conforming to the contour f of the spinnerette head 9. A screen of this type is advantageousin that it may be employed with bands in conjunction with the end piece H) of the frame l-2 hold the ends of the spinnerette head in place and seal the end portions of the spinnerette.

- An optional construction is also illustrated in Figure 3 and comprises the reinforcing bands 20 positioned at suitable distances along the length of the spinnerette head to impart rigidity to the structure. Since the extrusion pressure on the perforated portion is transmitted primarily to the longitudinal portion I! of the frame, the pressure at any point is the same irrespective of the length of the spinnerette, andthe bands are not essential. They do, however, assist in imparting ruggedness to the spinnerette.

If the reinforcing bands 20 are employed, their position is governed in part by the'thickness of the perforated portion of the'spinnerette. Thus, since a fine fiber requires a relatively thinner head, the bands 20 would preferably be somewhat.

into blocks and leaving channels into which the coagulating liquid can freely flow between said blocks and thus come into more efllcient contact with the extruded fibers.

It has been found that. the substantially semicylindrically shaped head, aside from allowing an indefinite extension in size of the spinn rette through extension of length, with the resultin capability of forming any predetermined number of fibers simultaneously. also provides a much more uniformand thorough coagulation of the extruded fibers. This is due in part to the extended length of the spinnerette head which enables a large number of fibers to be extruded in a relatively thin sheet. Thus the coagulating bath may come into contactwith all of the fibers in a very uniform manner and is not impeded in its contact'with the innermost fibers as was the case with the prior art spinnerettes.

The unirormity of coagulation oi the fiberslnu be furthersimpl-ified by a radial of the orifices. In this way, the fibers are separated a sufficient distance from-"eachother when they first come in contact with the bath to allow easy access of the bathto ever-yilber,and

also to allow each fiber to become sufilcie'ntly fixed by the bath before coming in contact with .other fibers so that blobbing or running together isreq duced to a minimum. Particularly with reference to the spinning of synthetic protein fibersirom' casein, ithas been found that-because ot'the'improved shape of thehead and the radial p sitioning of the orifices it is possible to efl'ect perfect coagulation with practically no blobbing or running together, even though the holes are tor-med as closely-together as 'six to eighthundred to the square inch.

The fabrication of a ccrdance with my invention is easier and more economical. than themanuiacture' of those of the prior art. The material forming the head may be drilled or punchedwhile in sheet iorm,

with the holes perpendicular to the plane suriace oi the sheet. Thus, the holes automaticallybecome radial to the axis of the head when the sheet is bentinto the desired semi-=cylindrical form. The sheet thus prepared may then be secured to the supporting frame 82 at end bands i8 and at the reenforcing bands 20 as already de= scribed.- The longitudinal edges are either welded or soldered to the side pieces of frame H or clamped by means of flange H to ,the distributor head 8, as shown in Figure 5.

It is thus seen that my improved spinnerette,

in addition to permitting a large number of orispinnerette formed in ac spinnerette and the withdrawing roller,

- tliefibers extruded-horn: the centrally l'ocatedg holes of the sp'innerette.- may be due in part to the fact thatitltese'fibers are farther from .the bulk 01 the coa ulating bath, and 'the'c'oagulating liquld'reaching the center fibers may be partially depleted-in passing through the outer] fibers. However, this action is reduced to a minimum. in accordance with my.- invention because of the'narrow lateral dimension. The fibers extruded from the outer holes, due to their curved path in the bath, exert a policing action whereby broken fibers are caughtup and carried-along by the main body or mass of fibers, and thus are kept from accumulating and necessitating the periodical. cessation of operation to remove them.

A -i 'urther advantage of a. spinnerette formed in accordance with my invention is thata major proportion of the extruded filaments, particularly those at the sides; are withdrawn from the spin riereti'le at an angle to the orifices therein. The

extrusion pressure upon the solutionis generally sufiicient to force the solution a little distance away from thespinnerette before it is turned'in the direction of pull on the'fibers. The curving in or the filaments as they are spun tends to-clrawv fiuidinto the center of .the mass of fibers, thus fices s'o spaced as to'make'ccagulation .efiective,

presents a well sealed, strong construction which is not susceptible todistortionor bulging. The

shape of the head is normally the most extended shape that the head can-'assuma and as the material of the head is well secured along its edges,

no distortion or bulging is possible, and the spinneretteretains its shape throughout its life.

Furthermore, the head furnishes a large enough reservoir withinthe spin-nerette tc'insure an equal extrusion pressure throughout th'e spin-'.

nerette and thus provides for a uniform extrusion speedat all parts of the head. This is not possible with a number of small spinnere'ttes in which the pressure may vary. In the event that setting up a circulation 'whichbrlngs a supply of fresh coagulating liquid to the inner fibers. This eifect is particularly desirable in the art of spinning synthetic fibers in which the coagulating liquid exerts a, chemical action,.that is to say, is used up as coagulation takes place. ,It is'desirable that each fiber be subjected to'a volume of co- .agulating liquidof uniform density and composition to insure uniformity of the fibers being produced.

In accordance with my invention, the spinnerettemay be formed of any of the metals-commonly used in apparatus of this type. The inert metals such as gold, platinum, and tantalum' may be used efiectively, except that'the same are easily abraded and are difficult to fabricate, par;-

ticularly where soldering is required. Satisfac-' tory results may be obtained with heavy metals, such as brass, particularly if they are given a plating of metal such'as nickel, which becauseof its passivity will not be t d by the c lating bath.

a relatively elongated head is used, it is.a mere 5 mechanical detail. to provide a larger reservoir behind the perforated surface to equalize the pressure. This'may be done in the manner shown in Figure 5 or by making the head:0concave inf shape. Alternatively, a plurality of supply pipes 3 may be spaced at sufiicie'nt distances along the back of. distributor head 8 to insure an equal extrusiorrpressure throughout the head from a, .common g'sour'ce under pressure. Alternatively a header oniieedeig pipe may be provided within In a process for the manufactureof staple fibers, in which process the fibers are cut into staple lengths at some stage in theirmanufac- 'ture, the production of fibers that are uniform as to diameter and other properties is exceedingly important, and the ability to spin fibers havinssuch uniformity is aided in a large measure by the use of a spinnerette'capableof spin-.

, ping from 5,000 to 10,000 fibers simultaneously, accompanied by more effective and uniform coagthe .head' qg thespinnerette withjoutlets so new lated and positioned that the volum'eot the B'Dinwillbe delivex duniformly throughlo sup ly nine.

oithe sphinerette. The tliatrlbutor' th $113 93? an be tli t with thelspinnerett'e' 1 'm ulation;

- In producing fibers-of very small diameter, a spinnerette producing f simultaneously a large number-oi fibers simultaneously is also an im-.-

portant-element. 'One or-the most advantageous ways of obtaining fiber or a. smaller diameter is to splitor subdivide a definite amount of the fiber forming solution into a greater-number ot;fibers. ..,Assuming that the amount of spinning solution applied to. aspinner'ette is constant, then a spine 'nere'tte with a larger number of holes must producefibers with a smaller diameterregardless o! thesis: of the opening. While it is true that other factors will 'afiect the diameter 01- the fiber such as thepressure applied to the spinning solu-- lidlin 'a-relatively straight jlltion therate of withdrawal ot'therormed flber etc., it has been found that by keeping all these other factors constant and by increasing the number of openings in the spinnerette, the desired smaller fibers having greater strength and other desirable properties are more easily obtained.

Itis obviousthat semi-elliptical,.parabolic and 7 other contours may similarly be advantageous in forming the spinnerette, and I intend these to:be* included in the expression substantially semicylindrical."

It will also be apparent that the above described spinnerette may be subjected to variations within the scope of my invention and it is to be understood that all the equivalent changes to which the form and method are susceptible areleast twice said diameter, said head being formed of a thin sheet of metal with holes therein radial to the axis of said semi-cylindrical head and spaced substantially oi the order of at least four hundred to the square inch, the thickness of said thin sheet metal being about twice the diameter of said holes, means for securing the base to the head with the head protruding outwardly from the base and forming a reservoir therebetween, at least one supply pipe connected with said base and of sufilcient size to maintain an equal extrusion pressure throughout the reservoir in said spinnerette.

2. A spinnerette comprising a base, a substantially semi-cylindrical head composed of a sheet of metal sufiiciently thin to be provided with orifices having a diameter of the order of about 100 to 125 microns positioned radially with respect to the axis of said head and spaced substantially of the order of at least four hundred to the square inch, the thickness of said sheet of metal being approximately twice thediameter of said orifices, means comprising an orifice for admitting thefiber forming material to the spinnerette, and means for firmly securing said head to the base of the spinnerette with the. head protruding outwardly from said base.

3. A spinnerette comprising a base, a substantially semi-cylindrical head composed of a thin sheet oi metal with a plurality of minute orifices therein through which the fibers are extruded, said orifices being radial with respect to the axis of said head, substantially semi-cylindrical bands ;positioned along the length of said head, theinner surface of said bands engaging .the outer @suri'ace of said head to reenforce the same, a

frame to which the bands and the head are atfixed to support the same and by means of which the head is attached to the'base', end pieces en- 1 g'aged with said frame, andat least one supply pipe coimectedwith said base through which the spinning solution is supplied and maintained at an equal pressure throughout the interior of said spinnerette.

4. A spinnerette comprising a base, a head substantially semi-cylindricalin shape the diameter of which is relatively small as compared with its length, said head being formed of a thin sheet or metal with not less than 5,000 holes therein radial go to the axis of said semi-cylindrical head, the

metal composing the substantially semi-cylindrh cal head being sufficiently thin to be provided with holes spaced substantially of the order of I not less than four hundred to the square inch and 2 less in thickness than twice the diameter. of said holes, a supporting frame to which said head is adapted to be fastened and 'by which said head is.-secured to the base of the spinnerette with said head protruding outwardly from said base and forming a. reservoir therebetween, at least one -supply pipe connected with said base and of sumcient size to maintain an equal'extrusion pressure throughout the reservoir in said spinnerette and means for fastening said head to said base.

5. A spinnerette'ior forming fibers, comprising a base, a substantially semi-cylindrical head piece'composed of a thin sheet of metal with radially extending flanges alongthe opposite edges thereof and having the portion thereof be- 40 tween said flanges provided with a plurality of 46 said head piece are adapted to be aflixed and by means or which the head piece is attached to and supported by the base with said head protrudin outwardly iromjsaid base, and pieces engaged with said frame and head-piece, and means in- 50 eluding at least one supply pipe connects with .saidbase through which the fiber forming mate-'

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