US3464197A - Covered yarn of plural elastomeric filaments secured in deformable planar relationship - Google Patents

Description

3,464,197 SECURED l N Sept. 2, 1969 TIN ,RIC FILAME E. V. MAR COVERED YARN OFIPLURAL ELAS'IOMF DEFORMABLE PLANAR RELATIONSHI 2 Sheets-Sheet l Fil'ed Nov. 28, 1966 EMME'TT 1/. MART/N a N E R M D .A w w m INVENTOR.

,arroR/ve'fs p 2, 1939 E. MARTIN 3,464,197

COVERED YARN OF PLURAL S'IOMERIC FILAMENTS SECURED IN DEFOHMABLE PLANAR RELATIONSHIP Filed Nov. 28, 1966 2 Sheets-Sheet 2 FIG IOA EMMETT l/ MART/N INVENTOR.

. v, ATTORNEYS United States Patent US. Cl. 57-152 10 Claims ABSTRACT OF THE DISCLOSURE An improved, covered, elastomeric yarn having a helically Wound cover over a core of from 3 to 5 substantially round elastomeric filaments securely adhered to one another in side-by-side relationship. When the core is i its most elongated or most relaxed state, the filaments define a curved configuration. The core has its greater circumference when it is in an intermediate state in which the covering is most relaxed and its smaller circumference when it is in the most elongated or most relaxed state so that a covering yarn applied in the elongatde state will be in tight, compressive relationship with the core both in its most elongated and also in its most relaxed state and in all stages therebetween.

This is a continuation-in-part of my earlier copending application Ser. No. 311,475 filed on Sept. 25, 1963, now abandoned.

This invention relates to elastomeric yarn, and more particularly to a composite elastomeric yarn having an elastomeric core comprising a plurality of round filaments adhered together and covered with one or more helical windings of a relatively fine denier yarn.

It is known to provide elastomeric yarns comprising an elastomeric core having a covering thereover. The coverings generally comprise a helical winding of a relatively fine denier yarn around the elastomeric core. The covering controls the stretch of the composite elastic yarn, and in addition may provide improved appearance, better hand and protection for the elastic core against perspiration, grease and the like.

In covering the elastomeric core, the core yarn is usually stretched considerably during the covering operation, and the covering yarn is wound on the core at a rather high helix angle. When the covered yarn is released from tension, it contracts in length until it jams against the cover yarn or has no tension. When the yarn is extended, the core contracts within the helix of the cover, first making the cover loose and, as the yarn is extended further, the helix again tightens against the core providing a stop at the upper limit of elongation. Within the operational range of elongation, the composite elastomeric yarns of the prior art have generally had an irregular appearance due to looseness of the covering yarn along the length of the core. This problem has previously been overcome effectively by providing a Y- shaped core for elastomeric yarns as described in Martin US. application Ser. No. 258,479, filed Feb. 14, 1963, now US. Patent 3,169,363 issued Feb. 16, 1965. Although the method described in that patent for overcoming the problem of looseness in elastomeric yarns is highly effective, it necessitates the melt-spinning of filaments having an odd-shaped cross-section, which in turn requires the provision of odd-shaped orifices in the spinning jet. The high pressure that the jets have to withstand in melt spinning necessitates a head of sufiicient ice thickness that the orifices must be drilled. This operation becomes quite expensive when odd-shaped crosssections, such as Y-shaped orifices, are required. It therefore appears desirable to overcome the problem of looseness in covering composite elastomeric yarns, and to avoid the cost encountered in previous attempts to solve this problem.

One object of my invention is to provide elastomeric yarns having a helically wound cover over an elastomeric core, which cover remains snug throughout the range of elongation of the yarn. Another object of my invention is to provide composite elastomeric yarns having greater elongation than is achieved with the elastomeric yarns of the prior art. A further object of my invention is to provide a method for economically preparing an elastomeric core which may be employed in composite elastomeric yarns of the type having a helical winding over the elastomeric core, which composite yarns may be stretched throughout the range of their elongation without the cover becoming loose. Other objects of my invention will appear herein.

These and other objects of my invention are accomplished by providing composite elastomeric yarns featuring an elastomeric core composed of 3 to 5 filaments adhered side-by-side to form an initially fiat ribbon, and providing one or more helically wound covers thereover. According to a preferred embodiment, my invention provides a covered elastomeric yarn comprising a helically wound fine denier yarn cover over a core composed of from 3 to 5 substantially round elastomeric filaments of a linear highly polymeric elastomeric synthetic fiberforming polymer having hard polymeric segments and soft polymeric segments, said filaments being securely adhered to one another in a side-by-side relationship having its least curved configuration when said cover is in its most relaxed state, said cover being in a tightly wound state when said core is at its maximum elongation or its minimum elongation and said side-by-side relationship is concurrently at a greatly curved configuration, whereby said composite elastomeric yarn is capable of being stretched throughout its range of elongation with said cover remaining snug around said elastomeric core.

I have found that the covers of composite elastomeric yarns in accordance with my invention do not tend to become loose at any point within the range of elongation.

The novel elastomeric cores of my invention may be prepared by extruding elastomeric polymers through round orifices which are easy to prepare. In some instances, the elastomeric cores of the invention may be melt-spun through commercially available melt-spinning apparatus. I have further found that it is possible to ob tain a higher covered yarn elongation with the novel elastomeric cores of my invention (which will be referred to hereinafter as multi-round cores) than with the previously used round monofilament elastomeric cores. The apparent reason for this increase in covered yarn elongation is that the yarns have a greater effective diameter; therefore, when they are stretched during the covering operation the diameter reduction is greater, and when the yarns are relaxed after covering they are able to take up a greater amount of the covering yarns without creating the problem of beadiness and uneven appearance.

In order to better appreciate the present invention, and to present a contrast for comparative purposes, assume that the core yarn is merely a round-section incom pressible monofilament. In such a case in the covering operation, the core yarn is stretched to a high degree, such as 300 to 500% or more, and the covering yarn is wound around the monofilament core at a high helix angle and under considerable tension. This tension causes the cover to exert a compressive force on the monofilament core yarn. As the covered yarn comes off of the covering machine, it is allowed to contract. During this contraction, the diameters of both of the monofilament core yarn and of the helix of the cover increase but they increase at different rates. At first, at the high helix angle, the rate of increase of the diameter of the helix is greater than that of the monofilament core yarn. As a result, the cover becomes loose on the monofilament core and no longer exerts a compressive force on it. As the yarn con tinues to contract toward low helix angles of the cover, the rate of change of diameter of the helix becomes less than that of the monofilament core yarn, with the result that the cover again tightens on the monofilament core and exerts a compressive force on it. At both high and low helix angles, the cover exerts a compressive force on the monofilament core, but at intermediate angles, the cover becomes loose on the core, permitting it to slide along the core and become beady in appearance.

It is apparent from the description in the prior paragraph that if core yarn is sufficiently compressible, its rate of change of diameter with contraction in length can be equal to the rate of change of the helix, thereby preventing looseness of the covering yarn at intermediate helix angles. The present invention provides a means of obtaining this desired compressibility. Referring now to to the drawings, FIGURE 2, 10, and 10a show the arrangement of four round-section filaments plastered together in a planar relationship to each other. This is the configuration in which four-filament core yarn is manufactured, according to this invention, and it is the configuration of the core yarn as it enters the covering operation. The compressive action of the covering yarn at the high helix angles encountered in covering forces the core yarn into a configuration which approximates that shown in FIGURE 11. That the change from FIGURE 10a to FIGURE 11 involves compressibility of the core with respect to the cover can be shown by consideration of the change in circumference of the core yarn. In FIGURE 10a, the circumference of the core yarn is about 9.14a', where d is the diameter of each filament, while in FIG- URE 11, the circumference is approximately 7.14d. The value 7.14d is what it would be in the configuration shown by FIGURE 4 and it is obvious that it would be about the same or possibly even less for the configuration shown by FIGURE 11. So far as the cover is concerned, the change from about 9.14d to about 7.14d acts the same as compressibility of the core. This is due to differences in the curved configuration of the side-by-side relationship of the core filaments. As the covered yarn is removed from the covering machine it can be considered to be at an upper stop in its permissible elongation due to the tightly wound cover having an effective diameter of approximately 7 to 8d. It is then allowed to contract and the compressive force of the cover is reduced, thereby permitting the core yarn to return elastically toward the less curved configuration of FIGURES 2 or 10 at some intermediate point (where the effective diameter approaches 9d) and then further return toward a bottom stop where, at this low elongation stop at low helix angles of the cover, the cover again compresses the core yarn into the configuration of FIGURE 11 having an effective diameter of approximately 7 to 8d. The resultant effect of this compressibility of the core is to keep the covering yarn from slipping on the core and becoming beady" in appearance.

According to this invention, compressibility is obtained for a multifilament core yarn by means of the change of curvature of a coherent strand of 3 to substantially round filaments which initially are securely adhered to one another in side-by-side relationship which is substantially planar. The change of curvature from the configuration of FIGURE 10 to that of FIGURE 11 reduces the circumference of the strand somewhat on the order of about 15-25%. The prior art does not appear to disclose this unobviously advantageous mechanism for obtaining compressibility.

This same mechanism applies to cores of 3 or 5 yarns as well as 4 yarns as has just been explained. Thus, the present invention provides a multifilament yarn in which the individual filaments are round in cross section and bonded together into an assembly which is useful as the core in a covered elastic yarn. The apparent elastic compressibility of the core that is needed to keep the cover from becoming loose on the core is obtained by use of a principle not heretofore known in the art, namely that of a deformation in the initially somewhat planar configuration of the core yarn in response to the compressive action of the cover.

My invention will be further illustrated in the accompanying drawings. FIGS. 1-4 show various configurations of multi-round cores, the configurations shown in FIGS. 1 and 2 being of the type employed in accordance with the present invention. FIG. 5 is a view of the method and apparatus employed for extruding the elastomeric cores to be used in accordance with the invention, and FIGS. 68 show guide members for adhering individual filaments into the multi-round flat ribbon cores to be used in accordance with the invention, and for contacting these cores to form a flat composite ribbon composed of a plurality of the multi-round cores not yet securely adhered to one another. FIG. 9 shows a plurality of the multi-round cores not yet securely adhered to one another to form a flat ribbon. FIGURES 10, 10a, and 11 have been discussed above, e.g., FIG. 10 shows a helically wound cover over an elastomeric core composed of four filaments securely adhered in side-by-side relationship in the form of a fiat ribbon, i.e., in substantially the same plane when the core is in its most relaxed state. 7

My invention will be further illustrated in the following example, and with reference to the accompanying drawings.

A polymer was formed from a dimethylterephthalate, 1,4 cyclohexanedimethanol and poly(tetramethylene glycol) copolymer having a molecular weight of about 4,100. This polymer, which contains about 84% by weight of the polyglycol, was melted at 265 C. and extruded at the rate of 7 pounds per hour. The process of extrusion will be better understood by referring to FIG. 5. The polymer was melted in a device not shown and the melt was extruded through orifices 22 of extrusion jet 20 to provide a plurality of round monofilaments 26. After traveling through air for about 5 inches, the filaments entered a bath of water 35 at 1 C., traveled through the water for a distance of about 4 inches, and then passed a little over around guide member 24, further illustrated in FIGS. 6 and 7. Guide 24 has provided therein concave notches 29 through which the filaments 26 were drawn. The notches 29 are formed in a flat metal plate 31 which is secured to guide member 24. The thin metal plate 31 provides a thin edge so that the notches exert little frictional drag upon the filaments. The shape of the notches 29 in plate 31 was altered so that filaments having cross sections of the type described in FIGS. 1, 2, 3, and 4 were obtained. The filaments 27, shown in FIG. 5, after traveling about 4 feet through the water bath approximately horizontally, were brought into contact with each other in a side-by-side manner at guide 25 fitted with a thin plate 32 having a notch therein 33. Upon the first contact at guide member 24, the filaments 26 were securely adhered together to form the multi-round cores 27 of the invention. When the separate multi-round cores 27 were brought together by notch 33 in guide number 25, the four-filament strands were separately adhered together to form a coherent flat ribbon 38. These ribbons were then dried and heat-set in a relaxed condition for 5 minutes in air at C. The individual four-filament multi-round filament strands 27 were separated from the composite fiat ribbon 38 with a comb, not shown, and elastomeric yarns were prepared from these four-filament multi-round strands, which had a denier of about 600, tenacity of 0.25 gram per denier and an elongation of about 600%. The strands were stretched 4.3 times for one set of data and 5.0 times for the next set of data, and covered top and bottom (two helical windings in opposite directions) with 40 denier nylon, using a commercial covering machine. FIG. shows a core composed of four multi-round filaments 40, in a strand with a single cover 41 wound thereover. The results obtained in covering such strands are shown in the following table.

The percent stretch off the covering machine, as shown in the columns of data represents the amount of actual stretch for the covered yarn coming 01f the covering machine as compared to its minimum elongation or bottom stop (BS) in the relaxed state. A value such as 220% means that the maximum elongation (top stop) for the yarn coming off the covering machine has a length in its covered form which is 3.2 times its newly established minimum elongation at the bottom stop (BS), i.e., 220% 100% (relaxed BS length) divided by 100% is a ratio of 3.2XBS.

In other words, the upper stop is at 4.3X based on uncovered filaments for column 1 and is at 5.05 based on uncovered filaments for column 2, and these same top stops have XBS stretch ratios shown in columns 1 and 2 of the table based on the relaxed length of covered filaments at the bottom stop (BS) of the covered filaments.

As a specific example of what is not included in my invention, see column 2(A) wherein the covered yarn having a core of four round filaments arranged in a square (see FIGURE 4) was stretched from its bottom stop of 1.0XBS to its top stop of 3.2XBS and had a had appearance from the standpoint of headlines.

Specific illustrations of this invention are set forth in column 1 at lines (C) and (D) and in column 2 at lines (C) and (D). In all four instances the covered strands had good appearance from the standpoint of headlines throughout their ranger of elongation from bottom stop to top stop. It is noted that the initial planar or substantially fiat configuration of the core filaments in side-byside relationship is only approached at the most relaxed point of the covering as the covered yarn is stretched from its bottom stop to its top stop.

6 '1 with my invention may be covered with a single covering of any of the yarns previously used for this purpose in the art. It has been found that nylon, cellulose acetate, rayon and polyester yarn covers give highly useful results. One or more covers may be applied to the multi-round, initially fiat cores of the invention; however, it is preferred to apply two helically wound covers, the windings being in opposite directions. The double covering reduces or eliminates twist liveliness that is sometimes present when only one cover is employed.

As noted heretofore, the multi-round elastomeric cores of my invention are preferably of substantially flat initial configuration. That is, the individual round filaments of the core are adhered to one another in side-by-side relationship in substantiallly the same plane prior to being covered. These cores have been found to provide the most satisfactory appearance in the helically wound elastomeric composite yarns of the invention. The multi-round cores of the invention may be prepared in any suitable manner, and preferably are formed by extruding individual monofilaments, and contacting them while they are still highly tacky to provide good adhesion between the individual round monofilaments of the multi-round cores of the invention. The number of multiround filaments in the cores of the invention are advantageously 3 to 5 filaments per core and most advantageously four filaments per core.

As indicated in the drawings and in the examples, after forming the flat multi-round cores of the invention, it is preferred to adhere a plurality of these cores, while the cores are still tacky, to form a flat composite ribbon composed of a plurality of these multi-round, flat cores separably adhered together. This concept is described in Martin US. application 259,114, filed Feb. 18, 1963, now abandoned. In accordance with this procedure, the use of winders and tubes for packaging elastomeric yarns, previously necessary in the manufacture of the yarns, is eliminated thereby reducing the cost in manufacturing and handling the yarns.

The composite elastomeric yarns featuring the fiat multi-round cores of the invention may be employed to produce a wide variety of fabrics. They may be used alone or in combination with other yarns to produce wearing apparel such as swim suits, brassieres, girdles, elastic Column 1 C olumn 2 Covering stretch ratio 4.3K Covering stretch ratlo 5.0K

Percent stretch ofi Percent stretch of? machine (XBS Appearance while machine (XBS Appearance while value for top stretching from value for top stretching from stop as multiple bottom stop to stop as multiple bottom stop to Cross-section shape of bottom stop) top stop of bottom stop) top stop (A) 4 round filaments in a square (Fig. 4) 220 (3.2XBS) 220 (3.2XBS) Bad. (B) 3 round filaments in a triangle (Fig. 3) 220 (3.2XBS) 220 (3.2XBS) Fair. (C) roamd filaments in a flat ribbon (Figs. 2 230 (3.3XBS) 220 (3.2XBS) Good.

on 10 (D) 3 round filaments in a flat ribbon (Fig. 1).... 220 (3.2XBS) 220 (3.2XBS) Do. (E) 1 round monofilament (not illustrated by a 210 (3.1XBS) 180 (2.8XBS) Fair.

As may be seen in the above table, multi-round filaments in configurations other than a substantially fiat ribbon, such as a square or triangle, produce composite elastomeric yarns, the covers of which have bad or at best fair appearance, as did the customary round monofilament core elastomeric yarns. However, the flat multiround filament cores of the invention produced good appearance in each instance, and moreover had a greater percent effective elongation than the round monofilament employed in the prior art.

The composition of the multi-round, flat ribbon cores of this invention may be any of those of the elastomeric cores employed in the art heretofore. A highly useful polymer for this purpose is the linear high polymeric elastomeric polyester described in the copending application of Bell et al., Ser. No. 215,768, filed Aug. 9, 1962, now US. Patent 3,261,812 issued on July 19, 1966.

The multi-round, flat elastomeric cores in accordance bandages and generally those applications wherein elastomeric properties are useful or desirable.

I claim:

1. A covered elastomeric yarn comprising a helically wound fine denier yarn cover over a core composed of from 3 to 5 substantially round elastomeric filaments of a linear highly polymeric elastomeric synthetic fiber-forming polymer having hard polymeric segments and soft polymeric segments, said filaments being securely adhered to one another in a side-by-side relationship, said core having its last curved, cross-sectional configuration and greatest circumference when said cover is in its most relaxed state, said cover being in a tightly wound state when said core is at its maximum elongation or its minimum elongation and is concurrently at a greatly curved cross-sectional configuration having a minimum circumference, whereby said composite elastomeric yarn is capable of being stretched throughout its range of elongation with said cover remaining snug around said elastomeric core.

2. The elastomeric yarn defined by claim 1 wherein the core has a helically wound cover thereover, the angle of the helix being highest when said core is in its most elongated state and lowest when said core is in its most relaxed state.

3. The elastomeric yarn defined by claim 2 wherein the filaments are essentially composed of a polymer formed by condensing dimethylterephthalate, 1,4-cyclohexanedimethanol and poly(tetramethylene glycol).

4. The elastomeric yarn defined by claim 1 wherein the filaments are essentially composed of a polymer formed by condensing dimethylterephthalate, 1,4-cyclohexanedimethanol and poly(tetramethylene glycol).

5. The elastomeric yarn defined -by claim 4 wherein the yarn cover is composed of nylon yarn.

6. The elastomeric yarn defined by claim 5 wherein the core has a helically wound fine denier nylon yarn cover thereover, the angle of the helix being highest when said core is in its most elongated state and lowest when said core is in its most relaxed state.

7. The elastomeric yarn defined by claim 4 wherein the yarn cover is composed of cellulose acetate yarn.

8. The elastomeric yarn defined by claim 7 wherein the core has a helically wound fine denier cellulose acetate yarn cover thereover, the angle of the helix being highest when said core is in its most elongated state and lowest when said core is in its most relaxed state.

9. The elastomeric yarn defined by claim 7 wherein the core has a helically wound fine denier polyester yarn cover thereover, the angle of the helix being highest when said core is in its most elongated state and lowest when said core is in its most relaxed state.

10. The elastomeric yarn defined by claim 4 wherein the yarn cover is composed of polyester yarn.

References Cited UNITED STATES PATENTS 913,856 3/1909 Sloper 57-144 939,839 11/1909 Himes 57-149 1,563,307 11/1925 Frank 57-144 1,621,348 3/1927 Boller 57-144 1,889,102 11/1932 Murphy et al 161-143 1,963,813 6/1934 Voorhis 57-152 1,990,849 2/ 1935 Wagon 57-162 XR 2,177,538 10/1939 Spencer 57-152 3,126,698 3/ 1964 Scharf 57-144 FOREIGN PATENTS 4,807 1908 Great Britain.

JOHN PETRAKES, Primary Examiner US. Cl. X.R.

PO-IOSO UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3: 9? Dated September Inventor) Emmett Virgil Martin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1 line 26 "gatde" should read ---gated---. Column 1, line 36, "elastomeric" should read -elastic---. Column 5 line 26 "FIGURE" should read ---FIGURES- Column 4, line 60, the word as--- should be inserted before "shown" Column 4 line 69, "separately" should read ---separably- Column 5 line 25, "5 .05" should read ---5 .OX--. Column 5 line 55, "beadlines" should read ---beadiness---. Column 5 line 37, "headlines" should read -beadiness- Column 5 line 58, "ranger" should read --ranges--- Column 6 line 3 6, "the" should read -these--. Column 6 line 68, "last" should read --lea.st-

SIGNED AND SEALED MAY 19197 (SEAL) Amt:

d d M, Fletch", I

Armfin Offleor mm E. souumm, m.

Muhamof Paints

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