US3526689A - Fused multifilament round spandex yarn - Google Patents

Description

Sept. 1, 1970 Filed April 5, 1968 A. F. JONES, JR, ET AL FUSED MULTIFILAMENT ROUND SPANDEX YARN 3 Sheets-Sheet 1 INVENTORS ALLEN R JONES, JR.

CHARLES H APPERSO/V ANDREW r w TER BY PH of ATTORNEY Sept. 1, 1970 p JONES, JR ET AL 3,526,689

FUSED MULTIFILAMENT ROUND SPANDEX YARN Filed April 5, 1968 3 Sheets-Sheet 2 20 INVENTORS v 4/ ALLEN P. JONES, JR. 3 CHA RL ES H. APPERSON ATTORNEY Sept. 1, 1970 p JONES, JR" ETAL 3,526,689

FUSED MULTIFILAMENT ROUND SPANDEX YARN Filed April '5, 1968 S'Sheets-Sheet 5 .w mmw S T RSIP Wm OEPA V T A N N0. R w m E MM AW mw B United States Patent 3,526,689 FUSED MULTIFILAMENIEI' ROUND SPANDEX YAR U.S. Cl. 264-403 6 Claims ABSTRACT OF THE DISCLOSURE Spandex yarn having a round cross section is produced by passing the multifilament yarn onto a rotating slanted surface, such as a bevelled ring on a roller, and rolling the plurality of filaments across the rotating slanted surface.

This invention relates to the spinning of spandex yarns. More particularly it relates to an improved method and apparatus for producing multifilament spandex yarns with a round cross section.

Spandex yarns which are spun on a multifilament stream in the conventional manner are coalesced and flattened during the spinning process. This flattening and fusion into a single fiat-sectioned fiber occurs at the coagulation roll, around which the filaments are passed as they move through the coagulation bath. Such fiat spandex yarn is satisfactory for certain uses.

In many potential applications however twisting of the flat fibers would result in undesirable irregularities in the thickness of the product. It is highly desirable therefore to be able to produce a multifilament spandex yarn of uniform round cross section. Various methods and processes have been proposed to achieve such yarns. One is the extrusion of a single filament or monofil into a coagulating or reacting media as described in Britsh Pat. No. 847,673. This involves extruding a stream of prepolymer as a monofilament into a bath containing a primary diamine so a sto thereby extend, set and cure the fiber. This has the obvious disadvantage of depending on a chemical reaction. Complicated and expensive equipment and controls are necessary to carry out this chemical spinning and rounding of a monofilament fiber.

Another method which has been proposed is the dry spinning of a multifilament stream from a spandex solution into a hot gas mixture followed by the twisting of the filaments into a single fused shape using an air jet twisting device as described in the U.S. Pat. No. 3,111,368 to Romano. In addition to the problems normally associated with dry spinning this process requires the expensive operation of a jet twisting device.

Yet another attempted solution to the problem is set forth in U.S. Pat. No. 3,161,706 to Peters. This patent describes a method said to produce round yarn wherein a multifilament yarn is first coalesced or fused under pressure in a coagulating bath and then, after fusion into a fused multifilament fiber, is given a false twist to impart roundness. This false twist is achieved by using a series of V-grooved rollers. This process requires elaborate multiple rollers with attendant machinery and controls. It also is difiicult to operate because the multiple filaments are coalesced to a fused state at the bottom of the V- grooves of the first two rollers so that the fused multifilament fiber initially assumes a triangular shape. This triangular shape must be connected to a round shape during the post-fusion twisting operation. This makes it quite difiicult to achieve a uniform round cross section in the final product.

Contrary to the teaching of the prior art, particularly Peters, we have now discovered that, unexpectedly, an

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improved mutlifilament spandex yarn of uniform round cross section can be made from the plurality of extruded and coagulated filaments in the coagulating bath by coalescing or fusing this plurality of filaments into a single multifilament yarn while simultaneously imparting a false twist to the yarn being formed by the fusion. This is quite dilferent from Peters who requires a fusion step prior to attempting to impart a false twist. We do not require a V-groove for our twisting step but roll the plurality fibers across a rotating slanted surface such as a bevelled ring mounted on a roller.

In the drawing:

FIG. 1 is a top view of an apparatus according to the invention showing an extrusion spinnerette and the filaments going from there to a bevelled ring mounted on a roller.

FIG. 2 is a side view of the apparatus of FIG. 1 with the roller carrying the bevelled ring mounted partly below the surface of the coagulating bath.

FIG. 3 is a side view of the apparatus of FIG. 1 with the roller carrying the bevelled ring mounted entirely outside the coagulating bath.

FIG. 4 is an isometric view of an assembled bevelled ring according to the invention.

FIG. 5 is an isometric view of one half of the ring in FIG. 4 showing the pins used to hold the two halves together.

FIG. 6 shows two bevelled rings mounted on the same roller with the bevelled surfaces facing in opposite directions.

FIG. 7 shows four bevelled rings mounted together on the same roller with the bevelled surfaces all facing the same direction.

FIG. 8 illustrates six different variations in the crosssection of bevelled rings according to the invention.

In FIG. 1 a plurality of individual spandex filaments 11 are extruded from a spinnerette nozzle 12 and pulled over bevelled ring 13 mounted on roller 14. The false twist imparted by the ring 13 is transmitted back through the fibers so that the plurality of fibers first comes together at about the point 15 and twisting together of the fibers occurs between the point 15 and the ring 13. No pressure is required at the point 15 or at any point before the filaments contact the ring 13.

As they are pulled around the roller 14 the filaments 11 first contact the ring 13 at a point 16 on the high edge that is, the edge farthest from the axis of rotation, and are then rolled down across the face 17 of the bevel and leave the ring 13 at the point 18 on the lower edge of the bevel. This rolling across the rotating slanting surface of the face of the bevel imparts a so-called false twist to the fibers. This false twisting serves to round the plurality of fibers at the same time that it is being fused and coalesced into a single multifilament yarn.

In FIG. 2 the roller 14 with the ring 13 is mounted with the lower portion below the surface of the coagulating bath 20. Thus in this embodiment the plurality of fibers 11 are submerged in the coagulating bath 20 until after they have been pulled onto the ring 13. In FIG. 3 the roller 14 and ring 13 are so mounted as to be entirely above and out of the coagulating bath. In this embodiment therefore the plurality of filaments 11 leave the coagulating bath 20 before contacting the ring 13.

The rotating slanted surface required for our invention is conveniently provided by attaching a ring with a bevelled edge to a conventional roller. It is to be under stood that the invention is not limited to this embodiment however and that the rotating slanted surface could be provided in other Ways. Thus a roller could be made with an integral raised ring or bevel on the surface, or a very narrow roller or wheel could be made with entire circumferential surface slanted.

We have found that a split ring with a slanted or bevelled surface is a preferred embodiment of this invention. In FIG. 4 the two halves 41 and 42 of the split ring are shown joined while in FIG. 5 only the half 42 is shown. The split ring can be held together on the roller in any manner desired. In the ring illustrated in FIGS. 4 and 5 pins 43 in the half 42 fit into holes 44 in the half 41. The pins are held and engaged by set screws 45.

For clarity and convenience the invention has been illustratd in FIGS. 1, 2 and 3 with only a single spinnerette 12 extruding fibers to be pulled around a single ring 13. In commercial production however a plurality of spinnerettes would be employed together with a plurality of rotating slanted surfaces such as the rings. Using our preferred embodiment of the split ring a plurality of rings could be mounted on the same roller. The bevel or slant can be different for rings on the same roller as in FIG. 6 or it can be the same as in FIG. 7.

As stated above the rotating slanted surface can be provided in any convenient manner. However provided, the slanted or bevelled surface must form an angle with axis of rotation no less than about 30 and no more than about 60, with between about 37 and 52 preferred. Our most preferred angle is approximately 45. When the slanted surface of the proper angle is provided in a split ring in our preferred embodiment the slope of the rest of the ring is not material. In FIG. 8 a variety of ring cross sections are shown. All have at least one slanted surface 17 while in embodiments (c) and (d) two slanted or bevelled surfaces 17 are provided on the same ring. Thus in embodiments (c) and (d) two diiferent yarns from two ditferent spinnerettes could be rounded on the same ring.

When yarn is rounded according to our invention the resulting product has the smooth appearance of round monofilament fiber while retaining the soft warm hand and texture of multifila-ment yarn. Yarns made according to our invention are more uniform in denier and in the stress resulting from a given strain than flat fibers. In addition we have found to our surprise that yarns rounded according to our invention can be elongated further before breaking than can comparable flat fibers.

Our process and apparatus are useful in the wet spinning of all types of so-called spandex yarns. These are spun from solutions of elastomeric polymers commonly referred to as poly(urea-urethanes) which are prepared by curing an isocyanato-terminated polyurethane with a diamine.

In the Examples I through III which follow two identical spinnerettes mounted side by side were used to simultaneously extrude two different sets of filaments into a coagulating bath at a spinning speed of 100 yards per minute. A roller was used with a bevelled ring according to the invention and was mounted with the lower portion in the coagulating bath. One set of filaments was pulled over the bevelled ring according to the invention to produce a rounded yarn of 140 nominal denier while the other set was simultaneously pulled over the plain portion of the roller to produce a conventional flat yarn of 140 nominal denier for comparison. In Example IV the round and flat yarns were run consecutively rather than simultaneously and the roller and ring were mounted above the bath so that the filaments left the bath before contacting the bevelled ring.

In the examples tenacity of the yarns was recorded as the grams per denier required to break the yarn. Elongation was recorded as the percentage of original length by which the yarn was stretched when it broke. The stress in grams per denier recorded when the yarn was strained to 300 percent elongation (stretched length totalling 4 times the original length) was also measured. In the case of Example I a Manra Strainometer was also used to measure the average stress in grams required to produce 210 percent elongation as well as the range of stresses observed.

4 All of the spandex Spinning solutions in the examples were stabilized with 1.5 percent by weight of an ultraviolet absorber and 0.5 percent of antioxidant, based on polymer content. All were pigmented with 0.5 percent by weight Ti0 and 0.0013 percent by weight of tinting pigments, based on the polymer content.

EXAMPLE I A stabilized and pigmented caprolactone polyester based polyurethane spandex polymer solution of 25 percent by weight total polymers solids in dimethylformamide solvent was extruded as a plurality of filaments into an aqueous coagulating bath containing 20 percent by weight dimethylformamide from a spinnerette containing 30 holes, each hole 0.10 millimeter in diameter. After two feet of travel immersed in the coagulating bath the fila ments pulled onto the roller and ring and passed around and 011? the roller and ring. After washing in hot water the yarns 'were dried over a roll, lubricated with a textile finish and wound on bobbins. Properties of the yarns produced are shown in Table I. In addition the Manra Strainometer showed an average stress for the round yarn of the invention of 24.2 grams with a range of only 1.2 grams between extreme values. For the flat yarn used for comparison the average was 35.5 grams and the range was 2.4 grams.

EXAMPLE II In this example yarns of 420 nominal denier were spun from the same polymer solution as that used in Example I and under the same spinning conditions except that the filaments were extruded through an 80-hole spinnerette in which each hold had a diameter of 0.10 millimeter. Properties of the yarns are shown in Table I.

EXAMPLE III In this example yarns of 420 nominal denier were spun using a caprolactone polyester-based polyurethane spandex polymer solution of 25 weight percent total polymer solids solids content in dimethylformamide solution was used. Equipment and conditions were the same as in Example I except that the spinning speed was 250 feet per minute. Properties of the yarns produced are shown in Table 1.

EXAMPLE IV A stabilized and pigmented caprolactone polyester based polyurethane spandex polymer solution of 25 percent by weight total polymers solids content in dimethylformamide solution was used. Yarns of 600 nominal denier were spun using the procedures and equipment of Example I except that the round yarn was made first and then the flat yarn, using the same spinnerette which had holes of 0.16 millimeter diameter. The roller with the bevelled ring was positioned above the coagulating bath. Spinning speed was 200 feet per minute. Properties of the yarn produced are given in Table I. In addition the Manra Strainometer showed an average stress for the round yarn of the invention of 70 grams with a range of 5 grams between extreme values. For the flat yarn used for comparison the average was 75 grams and the range was 6 grams.

TABLE I Stress at 300 Tenacity, percent strain grams per Elongation, in grams per Denier denier percent denier Example I:

lI tlotnd 629 550 192 t a 545 455 2 6 Example II 7 %lotnd 294 610 142 a 77 555 1 2 Example III: 9

glolnd g0 67 690 088 a 0 60 60 1 2 Example IV 0 '3 Round 586 0. 760 675 0. 102 Flat 586 0. 646 615 0. 116

What is claimed is:

1. Method of forming a fused multifilament polycaprolactone-based polyurethane-urea spandex yarn which comprises extruding a plurality of filaments of spandex into a coagulating bath and then bringing said filaments together on a slanted rotating surface prior to any appreciable fusion together of said filaments and rolling said plurality of filaments across said surface so as to fuse said plurality into a single multifilament yarn which simultaneously imparts a false twist to the forming multifilament yarn so as to provide a uniform round cross section in the yarn leaving said rotating slanted surface.

2. Method according to claim 1 wherein said plurality of filaments first contacts said rotating slanted surface while still submerged in said coagulating bath.

3. Method according to claim 1 wherein said plurality of filaments first contacts said rotating slanted surface after emerging from said coagulating bath.

4. In a polycaprolactone-based polyurethane-urea spandex yarn spinning apparatus, said apparatus including extrusion means for simultaneous extrusion of a plurality of filaments and bath means for the coagulation in a liquid bath of the individual filaments comprising said plurality of extruded filaments, the combination therewith of a ring having at least one beveled edge and mounted on a roller, said beveled edge providing a rotating slanted surface which receives said plurality of extruded filaments following their introduction into said coagulating bath but prior to any appreciable fusion together of said filaments and which then fuses said plurality of filaments into a single multifilament yarn while simultaneously imparting a false References Cited UNITED STATES PATENTS 1,151,487 8/1915 Loewe 264-103 X 1,341,745 6/1920 Hesse 264-103 1,366,162 1/1921 Clayton 264-103 1,389,517 8/1921 Kifsee 264-103 1,685,640 9/1928 Leaver 264-103 2,440,226 4/ 1948 Swank 264-103 2,786,737 3/ 1957 Hawtin et a1 264-103 3,124,628 3/ 1964 Hughey.

3,161,706 12/1964 Peters 161-177 X DONALD J. ARNOLD, Primary Examiner J. H. WOO, Assistant Examiner US. Cl. X.R.

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