US3069883A - Compressive fabric - Google Patents

Description

1962 A. BURLESON ETAL 3,069,883

' COMPRESSIVE FABRIC Filed Feb. 3, 1959 INVENTORS ATTORNEYS United States Patent F 3,069,883 COMPREdSIVE FABRIC Aaron Burleson and Mark N. Holmes, Burlington, N.C., assignors to Burlington Industries, Inc., Greensboro, NIL, a corporation of Delaware Filed Feb. 3, 195?, Ser. No. 790,912 8 Claims. (Cl. 66-178) The present invention relates to knit compressive fabric and is especially concerned with the provision of knit support hose for both women and men covering a full range of support. Other knit constructions, in addition to support hose, are also contemplated herein, as will be apparent from the ensuing description of the invention.

Broadly stated, knit support hose or other compressive fabric according to the invention comprise consecutive or spaced courses of covered (wrapped) or uncovered (unwrapped) synthetic elastomer yarn, namely, polyurethane yarn, such as that produced by E. l. du Pont under the name Fiber K and Vyrene by U.S. Rubber. The hose may be knit entirely with the covered or un covered polyurethane yarn or this yarn may be used in combination with other types of yarns. The compressive action of the hose or other fabric herein can be regulated in various ways, as hereinafter discussed, to provide a full range of support hose, i.e. fully surgical, semi-surgical or moderate support.

A variety of covering yarns may be used, e.g. silk, rayon and cotton but nylon yarn is preferred. The denier of the covering yarn can be varied depending upon other conditions, e.g. the denier of the core yarn and the nature of the ultimate product desired. Preferably, a multifilament covering yarn free of twist is used although monofilament yarn with or without twist may be utilized. Spun yarns may also be used for covering purposes. Typically, in the case of a 70 denier polyurethane core yarn for use in womens hose, especially desirable covering yarn is 40 denier, multifilament nylon yarn which is essentially twist-free or 2/20s elasticized yarn (Helanca type).

A desirable feature of the present invention is that the polyurethane yarn may be wrapped with only a single wrapping layer of covering yarn although plural wrapping layers may also be used. In the past, where a rubber core yarn has been used for support hose, a double covering involving Wrapping in opposite directions has been essential to eliminate torquing, facilitate dyeing, etc. The Fiber K polyurethane core yarn used herein, however, is peculiarly adapted for use with a single wrapping to give good dyeing, hand and other desirable characteristics in the finished product.

Support hose or other compressive fabric according to the invention may be either full-fashioned or seamless, i.e. they may be knit on full-fashion or circular knitting machines.

As indicated heretofore, the compressive nature of hose or other fabric according to the invention can be adjusted in a variety of ways to give a fabric having the desired degree of support. Typically, this may be accomplished by regulating the degree of fabric tightness, yarn denier or the like. Thus, for example, in the case of circularly knit fabric, a wide variation in the degree of compressibility or support may be obtained by changing the cylinder size of a circular knitting machine While maintaining a constant number of needles. Alternatively, the number of needles may be changed while the cylinder size is kept the same. With any given cylinder size, it will be recognized that an increase in the number of needles gives a more tightly knit fabric which in turn offers greater compressive or supporting action. Similarly, when using a fixed number of needles, e.g. 200, a reduction of the cylinder size from, for example, 3%." to

3,059,883 Patented Dec. 25, 1962 3", will give a tighter fabric and, therefore, increased support.

' least some portion of the stocking, e.g. the leg, foot and/or welt sections. However, in lieu of this, the yarn may be alternated with another yarn, preferably raw or elasticized nylon yarn (Helanca type stretch yarn) so that the polyurethane yarn appears only in spaced courses in the stocking, the spacing depending upon the ultimate degree of support desired. Conventional reenforcing type yarns may also be used, as may be desired, in the welt, heel and/ or toe portions, or otherwise.

' The degree of compressibility or support offered by hose or other fabric prepared according to the invention may also be at least partially controlled by the nature of the covering yarn. Normally, polyurethane yarn possesses a stretch of 600700% before wrapping, i.e. the yarn can be stretched to between six and seven times its length in the untensioned condition. For highly compressive purposes, the yarn should desirably retain a stretch between 100 and 500%, usually about 250%, after the wrapping operation. By knitting tightly, the stretchability of the covered yarn may be reduced by an additional 2050%, to exert an even greater compressive force. For semi-surgical support, the wrapped yarn may stretch 200 to 550% of its original length and for moderate support purposes, the wrapped yarn may stretch only 300 to 600% of such length.

The polyurethane core yarn is preferably wrapped while under tension for the purposes of the present invention. The amount of wrapping tension utilized depends upon various other factors, e.g. the degree of fluffiness and stretch desired at the end, the number of wraps to be applied, the degree of support, etc. As noted heretofore, Fiber K polyurethane yarn, prior to covering, normally has a 600700% stretch. Preferably, the polyurethane yarn is wrapped under a tension such that the core yarn is stretched to between 40% and 90% of its maximum length in the fully stretched condition, i.e. to a length between about 2.4 and 6.3 times its untensioned length. Usually, from 4 to 24 wraps of the covering yarn are applied per inch of tensioned core yarn although it will be recognized that this can be substantially varied.

Sufficient wrapping yarn should be used to eifectively cover the core yarn when the stocking or other fabric is worn.

After wrapping, the polyurethane yarn does not return completely to its original untensioned length due to the fact that the covering yarn exerts a slight degree of compression and tension on core. Normally, this means that the covered yarn in its relaxed state, is between about 5% and 40% longer than the polyurethane yarn in its original unwrapped condition.

Knitting of the stocking or other fabric according to the invention should also be carried out with the covered polyurethane yarn under tension. Usually, this tension should be sufllcient to stretch the yarn an additional 25 to 200%, typically from its relaxed condition in the covered state, this being dependent on type of wrap. All other conditions being the same, an increase in the knitting tension effects a corresponding increase in the compressive action of the stocking or other fabric.

As a typical illustration of operations according to the invention, womens full surgical stockings may be prepared as follows:

70 denier Fiber K polyurethane yarn is wrapped in conventional manner on a hollow spindle machine. The

e,oes,ssa

yarn is given a single warp of 40 denier, 34 filament raw, i.e. conventional non-stretch, nylon yarn. The wrap is applied twelve wraps per inch while the core polyurethane yarn is stretched about 60% of its maximum stretch, i.e. to about 4 times its length in the untensioned state. This is equivalent to approximately 30 wraps per inch of the wrapped yarn in the relaxed state. The thus wrapped yarn is then coned at a speed and tension such that the yarn relaxes to about one half of its original 60% stretch, i.e. the coned yarn is stretched about 30%, or about twice the length of the yarn in the unwrapped, relaxed state.

The wrapped yarn is then knit on a 340 seamless machine (3 /2 cylinder). The yarn is knit under tension such that it stretches an additional 25% of its total stretch during knitting. The wrapped yarn is knit exclusively throughout the leg of the stocking. The welt, toe and heel are knit with 100* denier multifilament stretch nylon yarn (Helanca) processed yarn as disclosed in US. Patents 2,019,183; 2,019,185; and 2,564,245. The resulting product may be dyed, boarded and otherwise finished to give a highly desirable womens full support stocking characterized by its softness and suede-like nature. Typically, when this stocking is stretched coursewise and tested conventionally under 1" and 2 stretch, the compressive force in pounds at the knee are about 1.50 and 2.25, respectively, and at the ankle, 1.75 and 2.65, respectively.

Instead of using stretch nylon yarn exclusively in the welt, toe and heel portions, one or more of these portions may also be knit throughout with the covered polyurethane yarn alone or in combination with stretch or raw nylon or some other yarn. Typically, one or more of these portions may be knit with alternate courses of polyurethane yarn and stretch nylon yarn.

As a further specific illustration, the procedure outlined above may be modified by using 2/ 20 stretch nylon yarn (Helanca) or a single 20 denier stretch nylon yarn as the wrapping yarn instead of 40/ 30 raw nylon yarn. In this modification, relaxation of the core yarn is further limited because of relaxation of the wrapping yarn. The 40/34 raw nylon covering yarn allows more relaxation in the core yarn and, therefore, gives a somewhat flufiier and softer stocking. However, the stocking obtained with 2/20 covering yarn or single 20 denier yarn is also very desirable and gives effective and full support.

While the foregoing illustrates the invention in connection with womens stockings, mens hose covering a full range of support may also be made in accordance with the principles herein disclosed. Typically, such mens hose may be knit on a conventional half-hose machine by knitting, for example, 70 denier, 140 denier or 280 denier polyurethane (Fiber K) yarn covered (wrapped), or uncovered (raw K yarn). The covered (wrapped) yarn may be covered with raw nylonyarn from 40 to 70 denier or elasticized yarn (Helanca type) from 2/20 to 2/40 denier applied under tension (equivalent to 50%-60% maximum stretch of the K yarn). The entire stocking or a portion thereof, e.g. the leg portion extending from below the knee to the ankle, may be knit with this covered (wrapped) or uncovered (raw) polyurethane yarn with or without other yarns to give the desired degree of support. The top portion of sock may be knit or laid in only with covered or uncovered K yarn for the purpose of supporting sock.

The various objects and inventive principles herein are. further illustrated by the accompanying drawings wherein:

FIGURE 1 is a side elevational view of a finished womens compressive stocking according to the invention;

FIGURE 2 is an enlarged view of the fabric encircled in the stocking shown in FIGURE 1;

FIGURE 3 is an enlarged view of an alternate fabric structure according to the invention; and

FIGURE 4 is a sectional view showing the wrapped polyurethane yarn used herein.

As will be apparent, the stocking S of FIGURE 1 comprises a welt' portion 2, including afterwelt 4, and leg and foot portions 6 and 8, respectively. In FIG- URE 2, the numeral 10 stands for the wrapped polyurethane yarn knit with the usual loop structure, a single wrap of nylon yarn or the like being designated at 12 in FIGURE 4, while the polyurethane core is shown at 14. The fabric of FIGURE 2 comprises consecutive courses of wrapped polyurethane yarn and, as indicated heretofore, this may apply throughout the leg portion of the stocking and/or the welt or foot portions, including the toe, heel and/or sole sections of the foot. FIGURE 3 shows an. alternative construction wherein the fabric is knit with alternating courses of the polyurethane yarn It and stretch nylon yarn 16 or the like.

It will be appreciated from the foregoing that hosiery or other products may be knit according to the invention herein to offer a complete range of compressive action or support. As will be apparent, typical variations include using the same denier elastomer yarn in every other course to knit a tight fabric for full surgical hose and a correspondingly looser fabric for semiand moderate support having the desired construction or compression.

Alternatively, it is possible to knit the same tightness of fabric every course with the elastomer yarn but, by using a difierent denier of polyurethane yarn, to attain the desired construction or compression of fabric to cover the range of full surgical, semi-surgical and moderate support hose. As a further alternative, it is possible to use the same denier elastomer yarn throughout and knit every course with this yarn for full surgical hose; knit alternate courses with this denier yarn using a Helanca type stretch yarn in the other courses to give a semi-surgical product; and for moderate support hose, the elastomer yarn may be knit in every third or fourth course using Helanca type or stretch yarn in the other courses. In other words, the compressive action may bevaried by regulating the spacing of the polyurethane yarn.

While nylon yarn, stretch or otherwise, is especially desirable for use herein for knitting in combination with the wrapped polyurethane yarn, other yarns, natural or synthetic may be used. T bus, for example, polyurethane tetrephthalate (Dacron) or other synthetic linear poly-- ester or polyamide yarns, rayon, cotton, silk, etc., are suitable for use herein.

The use of polyurethane yarn in the manner described erein offers a number of unique advantages over prior efforts involving the use of rubber yarns. For one thing, the polyurethane yarn use-d in the manner described makes it possible to effectively satisfy a very definite. need for a range of support hose covering full surgical, semi-surgical and moderate surgical, for both men and women. Furthermore, the polyurethane yarn may be satisfactorily used in much smaller deniers, e.g. one-third the denier in weight compared to rubber yarn to give the desired range of compressive action or supporting power. Full and semi-surgical hose according to the invention demonstrate sheerer and softer characteristics and when dyed the appropriate shade, appear much more skin-like than rubber surgical hose and a regular sheer stocking may be placed thereover without the tell-tale detection that a surgical stocking is underneath. The hose demonstrate an improved liveliness that gives a better and smoother fit. At the same time, the present hose are more comfortable to wear in that they avoid the clarnmy feeling of conventional rubber surgica hose. The fabric also effectively hides blemishes and broken veins.

In addition to providing a full range of support hose for men and women, the invention contemplates-other fabrics wherein some degree of compressive action is desirable, such as circularly knit or full-fashioned tights, leggings or sleeves for angle or knee support or the like. In such cases, any of the variations heretofore mentioned may be utilized. Usually, in the case of tights a bigger core yarn and heavier wrap are desirable since less compressive force is necessary. For tights and supports, it is normally preferable to knit or lay in the wrapped or unwrapped polyurethane yarn in combination with stretch yarn (e.g. Helanca type yarn). Such combinations may include spaced or alternating knit courses of the polyurethane yarn and nylon yarn throughout at least a portion of the fabric, e.g. the legs only of tights. Alternatively, the fabric may include a series of consecutive courses of polyurethane yarn and a series of consecutive courses of nylon yarn. The polyurethane yarn may also be knit in such combinations with nlyon yarn or the like in the heel, sole and/ or toe areas of conventional full fashioned or seamless hose for the purpose of improving boarding and/or the fitting properties of the foot. If desired, the polyurethane yarn described herein may be either knit or laid in half-hose tops to facilitate retaining the hose in position on the leg. For this purpose, a 280 denier covered polyurethane yarn laid in is of particular value.

Support hose wherein the polyurethane yarn is laid in are described in our copending applications, Serial No. 749,394, filed July 18, 1958, and now abandoned, and Serial No. 756,012, filed August 19, 1958, now Patent No. 2,949,023.

Having described various modifications of the invention, what is claimed herein as new is:

We claim:

1. Support hose comprising knit courses of elastomeric polyurethane yarn throughout at least the leg portion, said yarn being wrapped with multifilament stretch nylon yarn.

2. Support hose comprising courses of 70 to 280 denier elastomeric nonfoamed polyurethane yarn at least throughout the leg portion of said hose, said yarn having been wrapped under tension with a single layer of multifilament stretch nylon yarn of lower denier within the range of about 40 to 140 denier.

3. Support hose comprising polyurethane yarn knit in every course throughout the leg portion of said hose, said yarn constituting a single elastomeric polyurethane core yarn knit under tension and having at least one layer of different wrapping yarn thereon, said wrapping yarn having been applied to said polyurethane core yarn while the latter is in a tensioned condition such that said polyurethane yarn is stretched to between about 40 and 90% of its maximum stretch in the unwrapped condition and the wrapped yarn, in its relaxed state, is between about 5 and 40% longer than the relaxed yarn before wrapping.

' 4. Mens support hose comprising knit courses of a 7 single 70 to 280 denier elastomeric polyurethane core yarn knit under tension throughout at least the leg portion of said hose, said yarn having been wrapped under tension with at least one wrapping layer of /34 stretch nylon yarn.

5. Knit tights comprising a body portion and leg portions, said portions being knit essentially throughout with wrapped elastomeric polyurethane yarn, said yarn comprising a single elastomeric polyurethane core yarn wrapped with stretch yarn and knit under tension.

6. A knit compressive fabric comprising courses of wrapped yarn, said wrapped yarn comprising a single core of elastomeric polyurethane yarn wrapped under tension with a single layer of multifilament stretch yarn different from said core yarn.

7. A knit support garment comprising a tubular support portion having elastomeric polyurethane yarn knit in all of the stitches in at least a substantial portion of the courses of said support number, said yarn being knitted under substantially constant tension while stretched to a length which is about 25 to 200% greater than the length of the yarn in its relaxed state before knitting.

8. Womens support hose comprising courses of 70 denier elastomeric polyurethane yarn, at least throughout the leg portion, said yarn constituting a single non-foamed elastomeric core yarn knit under tension and previously wrapped under tension with at least one wrapping layer of 2/20 stretch nylon yarn applied to the polyurethane yarn while the latter is under tension such that said polyurethane yarn is stretched to between about 40 and of its maximum stretch in the unwrapped. condition and the wrapped yarn, in its relaxed state, is between about 5 and 40% longer than the relaxed yarn before wrapping.

References Cited in the file of this patent UNITED STATES PATENTS 1,759,497 Weintraub May 20, 1930 1,822,847 Adamson Sept. 8, 1931 2,013,396 Adamson Sept. 3, 1935 2,441,085 Schneider May 4, 1948 2,625,535 Mastin et a1 Jan. 13, 1953 2,702,998 Purcell Mar. 1, 1955 2,720,097 De Mond Oct. 11, 1955 2,902,819 Ross Sept. 8, 1959 2,962,885 Knohl Dec. 6, 1960 3,001,359 Simon Sept. 26, 1961 FOREIGN PATENTS 212,617 Australia Dec. -17, 1957 766,975 France Apr. 23, 1934 1,150,358 France Aug. 5, 1957 282,534 Great Britain Dec. 29, 1927 674,989 Great Britain July 2, 1952 795,538 Great Britain a- May 28, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Non 3,069,883 December 25, 1962 Aaron Burleson et a1,

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 1 for "warp" read wrap line 40, for "40/30" read 40/34 column 5 line 3, for "angle" read ankle column 6, line 18, for "portion" read number line 19, for "number" read portion Signed and sealed this 3rd day of September 1963,

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

Images