US2834046A - Spinneret arrangement - Google Patents

Description

y 13, 1958 F. HESSELINK 2,834,046

SPINNERET ARRANGEMENT."

Filed June 13, 1955 INVENT OR FransjYesselzM BY QZZW'V 7 ATTORNEY United States Patent SPINNERET ARRANGEMENT Frans Hesselink, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N. C., a corporation of Delaware Application June 13, 1955, Serial No. 515,146

Claims priority, application Netherlands June 17, 1954 8 Claims. (Cl. 18-8) This invention relates to a process and apparatus for the manufacture of rayon threads for yarns and is more particularly concerned with the manner in which freshly spun yarns are initially contacted by the spin bath solution.

In the wet spinning of rayon one of the problems that is always present is that of providing adequate time for the coagulation of the cellulose xanthate into a form having suflicient mechanical strength to withstand drawing off. In the case of continuous spinning it is also necessary to allow time for adequate regeneration before beginning aftertreatment.

In the early days of continuous spinning, the problem of regeneration time was met by allowing the freshly spun acid-wet thread to move along a thread-storage, thread-advancing device, the sole purpose of which was to allow for additional time before aftertreatment. It has always been recognized that the time necessary for coagulation is a major limiting factor on spinning speed for, in addition to the fact that adequate storage time must be provided, if the spinning speed is too high, serious filament breakage occurs adjacent to the spinneret. This,

breakage probably results from the fact that the draw-off rate is too high for the mechanical strength of the delicate filaments before they have adequately reacted with the acid of the spin bath. Of course, viscose spin baths vary somewhat in composition as do the spinning solutions. Consequently, another problem is that certain types of viscose coagulate with much greater difiiculty than others and these have to be spun at a lower speed.

It is an object of the present invention to provide a method and apparatus for contacting freshly spun rayon with the spin bath in such a way that coagulation is greatly accelerated whereby the mechanical strength of the freshly spun yarn is quickly achieved with resultant permissible increase in overall spinning speed.

It is proposed according to the present invention to bathe the outer surface of the spinneret with rapidly circulating spin bath solution flowing radially inwardly m the margins of the spinneret to the axis of the bundle,

khen merging with the newly formed bundle and drawingoif the bundle and solution in a direction coaxial with the axis of the spinneret.

A further advantage of the present invention is that breakage of the filaments adjacent to the spinneret is greatly reduced. By contactingthe freshly spun filaments with spin bath according to the present invention, the friction of the spin bath in relation to the freshly formed yarn is reduced with corresponding improvement in residual stretchability and mechanical strength of the finished yarn.

Other objects and advantages of this invention will be apparent upon consideration of the following detailed description of several embodiments thereof in conjunction with the annexed drawings. Although only two specific embodiments willbe described in detail hereinbelow, it will be apparent open study 'of this specification that other apparatus employing the principle set forth above could be utilized.

Figure 1 is a view in section of a spinneret and spin bath supply assembly according to the present invention; and

Figure 2 is a view also in section of a modified type of assembly intended for immersion in an ordinary spin bath container.

Referring first to Figure l, the conduit 10 is the supply line for the spinning solution and this conduit 10 terminates in a flared month which is clamped between washers 11 by a hollow plug 12 which is screwed into a cavity in a body 13. The body 13 has a central aperture or channel at 14 which constitutes a coaxial extension of the conduit 10. It also includes a coaxial, frustoconical portion 15 which leads to a spinneret 16 having a plurality of spinning orifices. The spinneret 16 is provided with flanges which are clamped against a washer 17 by a cap 18. The cap 18, when in position, presents an end face 19 which lies flush with or in the plane of the outer surface or flat face of the spinneret 16.

The body 13, in addition to supporting the spinneret 16 at the end of frusto-conical conduit 15, also provides an annular cavity at 20 which is fed with spin bath solution through a conduit 21. The annular cavity 20 communicates with another annular cavity 22 which coaxially surrounds the common axis XX of the conduits 10, 14 and 15, as well as the spinneret 16. The inner surface of the space 22 is defined by the outer surface and end face 19 of the cap 18. The outer surface of the space 22 is defined by an annular body 23 which is threaded at 24 into the body 13. The body 23 receives a threaded end of a conduit 25 at its other end. Between the body 23 and 13 there is clamped a sealing gasket 26 and an annular strainer 27 in the form of a screen made from steel wire. The mouth of the conduit 25 is flared or trumpet shaped at 28.

When a spinning solution is supplied through the conduit 10 it is extruded through the multiple orifice spinneret 16 and the resulting bundle of filaments passes coaxially away from the region of extrusion through the conduit 25. The coagulation thereof is effected by supplying spin bath solution through the conduit 21 to the annular chamber 20. This solution passes through the screen 27 and into the chamber 22 which is in the shape of an inverted U in diametrical section and which is comprised of a cylindrical part 22a and a disc like part 22b. The chamber 22 is smaller in cross sectional area than the chamber 20. This results in an acceleration of the spin bath solution. As it leaves the portion 220 of the chamber 22, it moves radially inwardly in the portion 22b across the face of the spinneret 16 intimately to contact the freshly extruded filaments. It then merges with the filaments and moves out coaxially with the same through the conduit 25 along the axis XX marked in Figure 1.

It Will be appreciated that the width of the portion 22b of the chamber 22, that is the dimension parallel to the axis XX, controls the velocity of the radially moving spin bath solution. In order that the width of the portion-22b of the chamber 22 be made adjustable, the sealing gaskets 26 can themselves be or may be associated with spacing shims, rings or the like. It will be appreciated that one of the effects of the construction of the present invention is the reduction in dead space laterally of the freshly extruded bundle of yarns.

In Figure 2 the numeral 29 represents a fragment of a spin bath container. Within this container there is located a spinneret assembly with the axis of extrusion aligned with a conduit 30 having a flared mouth 31. In this case,

the spinning solution is supplied through a conduit 32 which is held by a flange 33 between overlapping sleeves Hand 35-aractly in the manner of the corresponding part shown inFigure 1.. A cap 36threadedlyengagesoaeend of the sleeve 35 and holds thereon a spinneret 37 also in the manner shown in Figure 1. The spacial relationship of the end-of thecap 36 tothe mouth ofiitheconduit' 30 is such as to provide a narrow space inn-plane normal; to-the axis of extrusion. The head ofspin' bath inthe container 29-will cause flow of solution in-the-direction of the arrows into this narrow space to move radially inwardly toward the axis of extrusion and to contactthe freshly formed filaments, then to turn and emerge with the filaments through the conduit 30 along the arn'sY-Y shown in Figure 2. While no means is shown for mounting the. spinneret assembly in. the-bath container 29, it to be: understood that any conventional means can beused so long as it is capable of controlling the width of the space between the end of the cap 36-and the wall of the spin bath container 29. It is, ofoourse, alsonecessary that the orientation of; the spinneretpartsbe-such astto keep them on the axis Y-Y. It wilI beappreciated that the spacial relationship between the face: of the spinneret and the coplanar end face of the cap'36 in relation to the mouth of the conduit 30 will determine the mouth coaxial with but spaced slightly from the face of degree of acceleration of the spin bath liquid and hence the velocity with which this liquid flows radially inwardly from the margins across the region immediatelyadjacent to the outer face of the spinneret.

The diameter of the channel 28-and the width of the portion 22b of the chamber 22 areselected with the anticipated working condition in mind. In vthe'caseof viscose threads of SOOdenier, the interior diameter of the channel28 may be 9 millimeters. 0n the other: hand, for threads of 1500. denier, a channelsize of -16-millimeters is necessary. The width of the-portion 22b-of the chamber 22 is especially dependent upon the interior diameter of the channel 28. The width amounts-in general, and in any case at the narrowest place, to only-a few millimeters and is so adjusted that the velocity of. the coagulating liquid increases rapidly. 'It was found that favorable results could be achieved if the ratio between the velocity of the coagulatingdiquid attire exterior rim of the guiding body surrounding-the spinneret (part 18) and that of the liquid in. the channel 28".lies above 1 to 3. These same dimensional relationships apply to the corresponding parts in thecaseoflFigurei. By adjusting the width of the zone 22b, or its equivalent, it is possible to make the speed ofthe. coagulating liquid equal the velocity of the freshly spun yarnafterthe coagulating liquid has made its turn'and. is moving-with the yarn toward the'outlet.

While the invention has been described with reference to viscose spinning, it is evidently applicable to all wet spinning processes.

Inasmuch as other embodiments will become apparent to those skilled in this art, it is intended that the scope of the present invention be limited only to the extent set forth in the following claims.

What is claimed is:

1. A spinning apparatus comprising a spinneret having a flat outer face extending normal to an extrusion axis, first means defining a surface flush with the face of said spinneret and extending radially from the periphery thereof, a conduit having a mouth coaxial with but spaced slightly from the face of said spinneret, second means defining a Surface flush with and extending radially away from the mouth of said conduit, said first and second means defining therebetween an annular zone surrounding the extrusion axis, and means to circulate coagulating liquid radially inwardly through said zone and coaxially into said conduit.

2. A spinning apparatus as set forth in claim 1 wherein themouth of said conduit is flared outwardly and faces said spinneret. T

3. An apparatus for the wet spinning of'syn'theticyarn comprising a spinneret having a fiat outer face extending said spinneret, second means defining a surface flush with and extending radially away from the flared mouth of said conduit, one of said means'being adjustable toward and away from; the-other, said first-andsecond means defining therebetween an adjustable annular zone surrounding the extrusion axis, and means to circulate coagulatingliquid radially inwardly through said zone and coaxially into said conduit.

4. An apparatus for: the wet spinningot synthetic yarns as set forth in claim 3 wherein said second means includes a wall of a spin bath container whereby the spin bath liquid will be delivered-to said annular zone by the head of liquid in said container.

5. Apparatus for the wet spinning of synthetic yarn that comprises a spinneret, a cap for supporting said spinneret, the end of said cap being flush with the face of said spinneret, means defining a conduit having'a flared month coaxial with but spaced from the faceof said spinneret, said means and the end of said cap defining therebetweenan annular zone surrounding the extrusion axis and immediately adjacent to but extending in a direction-parallel with and outwardly from the face of the spinneret, andmeans to deliver coagulating liquid uniformly about the margin of said zone for radial inward movement thereacross;

6. Apparatus for the wet spinning of synthetic yarn that comprises a spinneret, a capfor supporting said spinneretjthe end of said cap being flush with the face of said'spinnerer, means defining a first conduit having a flaredmouth coaxial with but spaced from'the face of the spinneret, said means and the end of said cap defining therebetween an annular zone surrounding the extrusion axis and immediately adjacent'to but extending in'a direction parallel with and outwardly from'the face'of the spinneret, means defining a second conduit for supply ing spinning. solution to-said spinneret, means defining; an annular space surroundingsaid second conduit, annular space communicating with said'zone' and extending in a direction normal thereto, andmeanstosuppl'y a coagulating-liquidto said annular space-for circulation thereth rougmand radial inward movement across said zone;

7. Apparatus for wet spinning as'claimed'in "claim6 in which the cross sectional area of said "zoneis less than the 'cross-scctional-area of'space communicating therewith whereby the now of liquid "entering said'zonc will beaccelerated.

8. In.the method of wet spinning including the steps of flowingaspinning solution to a region of extrusion, extruding said solution through a spinneret into a coagulatingliquid in the form of a plurality of filaments arranged in a bundle'around an axis, and'thereafter with drawing the bundle of filaments and coagulating'liquil together along said axis from the region-of extrusioo through a confined zone, the improvement comprisin the step of flowing said coagulating liquid radially toward the extrusion axis while confining the flow thereof to azone normalto said extrusion axis and contiguous to but extending outwardlyfrom the face of said spinneret.

References Cited in the file of this patent Germany Mar. 20, 1943

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