CA1151888A - Knitted elastic bandage - Google Patents

Abstract

ABSTRACT OF THE INVENTION

A lightweight, porous knitted elastic bandage is produced from a warp comprising a set of texturized or false-twist yarns knit in a chain stitch and a set of texturized or false-twist float yarns, both sets being held together by an inlay of non-texturized filling yarns. The filling yarns are deployed in a regular and repetitive pattern across the chain-stitch warp yarns and are interknitted therewith, but are not inlaid with the float yarns, successive filling yarns passing respectively above and below the float yarns.

Description

KNITTED ELASTIC BANDAGE

This invention relates to a knitted elastic bandage for light or moderate support or compression when applied to body members.
More particularly it relates to knitted li~htweight elastic bandages containing float yarns in the warp.

BACKGROUND OF THE INVENTION

~istorically, elastic bandages have been made in a woven structure, using narrow or ribbon looms, wherein the retractive and support-ive power has been supplied by special warp yarns. Early bandages employed overtwisted cotton warp yarns, as shown in the ~reufel 1908 U.S. Pat. No. 889,827, or in the Klein 1932 U.S. Pat.
No. 1,875,740.

The use of cotton warp yarns has been displaced to a considerable extent by the use of elastomerlc warp yarns, initially of ex-truded or cut rubber, more recently of other elastomeric manmade polymers. Such elastomeric warp yarns are usually wrapped with a layer of non-elastomeric filaments.

Such bandages, although effective in use, suffer from the disadvantage of being relatively expensive. They are produced singly on a narrow loom, utilizing expensive wrapped elastomeric yarns, at comparatively slow production rates inherent in the weaving process.

In an attempt to circumvent the limitations of the weaving process, it has been proposed to produce elaskic bandages in a knitted structure, as in U.S. Pat. No. 3,965,703, to Barnhardt.

The knit structuresthus ~ar, h`owever, still employ elastomeric yarns as part of the warp structure, and customarily employ very heavy filling yarns to prevent necking-in of the bandage when stretched. They are relatively heavy in weight, averaging 6 to 12 oz. per square yard (204 to 408 grams per square meter), and due to their compact structure they become hot and uncomfortable to wear.

In our patent No. 4,173,131, we have described the production of a lightweight elastic bandage in which the warp yarns consisted of a set of false-twist yarns formed into stitch loop chains, each of said yarns having inlaid therein a second false-twist yarn of opposite direction of twist from the chain stitch yarns.
The filling yarns are deployed across the warp yarn in varied and cursive patterns across the warp yarns, so that overlying layers of the bandage cling to each other in relatively non-displacable relationship.

Bandages of this nature, eminently satisfactory in use, are relatively complex to manufacture due to the necessity of forming every warp yarn into chain-stitch configuration with a second warp yarn inlaid therein, and to the intricate pattern of the filling yarnsD It is with improvements in the art of producing lightweight elastomer-free knitted elastic bandages tha-t the present invention is concerned.

i18~8 SUMMARY OF THE INVENTION

The elasticity of the bandages of this invention is provided by the inherent elongation and recovery of so called texturized or false-twist yarns. Such yarns are continuous filament yarns which have been given increased bulk and loft, together with recoverable stretch, by the introduction into the yarn of crimps, loops, coils and crinkles by false-twisting. The terms texturized or false-twist as applied to yarns are used synonymously herein, and refer to yarns, described above, which have been *exturized as by twist-set-untwist processes or by aerodynamic devices. Such yarns are commercially produced by well-known, processes, and when the filamentary material is thermoplastic, as is the case with nylon or polyester, a heat-setting stage in the false-twist process renders the stretch and the crimped conf;guration of the yarn relatively permanent.

Depending on the direction in which the yarn is twisted in the false-twist process, yarns may be twisted clockwise or counter-clockwise, giving rise to so-called S or Z twist yarns. In most lightweight bandages it is desirable to use a substantially balanced number of both S and Z twist yarns in the warp, to minimize the tendency of such bandages to twist when unrolled.

The bandages of this invention comprise false-twist yarns in the warp, arranged in two different configurations. One set of warp yarns is arranged in a series of chain stitches, and another set of warp yarns is arranged in a so-called "float" configuration -- - that is, the float yarns are not interknit with either the filling yarns or with the chain-stitch warp yarns.

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The warp yarns are held ~ogether by sets of filling yarns arrayed in regular repetitive pattern across the warp yarns, said filling yarns being of a non-stretch nature, preferably spun yarns of rayon or cotton. The filling yarns are interknit with a number of the chain stitch yarns, but merely pass over or under the float warp yarns without being interknit therewith.

To minimize the tendency of such bandages to twist or curl, it is preferred that there be substantial e~uality in the torque con-tributed by S-twist and by Z-twist yarns forming the total warp of the bandage. This may be effected by various means, as set forth in more detail below.

This invention will be better understood with reference to the following description and drawings, in which FIGURE 1 is a magnified isometric view of one repeat of the basic structure of a preferred embodiment of the invention.

FIGURE 2 is a magnified cross-sectional view of a false-twist yarn 22, with texturized filaments 24, characteristic of the yarns em-ployed in the warp of the bandages of this invention.

FIGURE 3 represents schematically the paths of the warp yarns 12 and 14 and one set of filling yarns 16 in the segment of bandage of FIGURE 1, inlaid in warp yarn 12 at 20.

FIGURE 4 represents the paths of both sets of filling yarns interlacing with a warp yarn at 26.

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FIGURE 5 represents in magnified detail the interlacing of both sets of filling yarns 16 and 18 with a representative warp yarn 12 formed into a chain stitch.

Referring to FIGURE 1, representing one repeat of a preferred form, the bandages of this invention, shown generally at 10, com-prise two sets of warp yarns, 12 and 14, both of a texturized nature and capable of elongation. Yarn 12 is formed into a series of chain-stitch loops, with a pair of non-texturized filling yarns 16 and 18 inlaid in the loops of yarn 12. Texturized yarn 14 merely passes between the filling yarns 16 and 18 r and is not interknitted with the other yarns of the bandage. It is, there-fore characterized herein as a float yarn, adding stability to -the bandage and increasing the cover factor (number of yarns per inch divided by the square root of the yarn size). The preferred range of combined chain-stitc~ and floatyarns is from 20 to 40 yarns per inch, ranging in size from 70 denier to 230 denier.

Both the chain-stitch yarns and the float yarns may be mixed S-twist and Z-twist. They are not necessarily drawn in in strict alternation, since a beam of S yarns and a beam of Z yarns may be intermingled randomly to provide a stable torqueless bandage provided that the number of yarns of each type of twist is sub-stantially equal. Also, it is not essential that there be an equal number of float and chain-stitch yarns in alternation across the width of the bandage. Since the fl~at yarn ~unction is primarily to add stability and weight to the bandage, the ratio of chain-stitch yarns to float yarns may vary from two or more to one to one to two or more depending on the size of the yarns.

Alternatively, a more convenient method of balancing S~twist and Z-twist yarns i5 to have all the chain-stitch warp yarns of one type of twist and all the float yarns of the opposite twist. This is the preferred method when there are approximately e~ual numbers of chain-stitch and float yarns, of similar degrees of twist.

At 20 in FIGURE 1 the filling yarns 16 and 18 are shown as being inlaid in the loops of the chain-stitch yarns 12. It is not essential that these filling yarns inlay in the l~ops of every chain-stitch yarn as shown in FIGURE 1. The principal function of the ~illing yarns, apart from holding the warp yarns in an integral structure, is to provide transverse stability and resistance to narrowing of the bandage when stretched. This will vary with the size and number of filling yarns, which are prefer-ably cotton yarns of a size ranging fro~ 10/1 to 30/1, with from 10 to 20 filling yarns per inch of bandage length.

The filling yarns are deployed in a regular and repetitive fashion across the warp yarns, each filling yarn extending preferably over from 5 to 9 warp yarns .

PREFERRED EMBODIMENT OF THE INVENTION.

Using a crochet machine, a bandage was constructed utilizing three yarn guide bars per repeat operating in a vertical plane perpen-dicular to the horizontal needles. Two of the bars moved across the width of the bandage -to insert the filling yarns 1~ and 18 of 20/1 cotton, and the third bar was utilized to insert the textur-ized float yarns 14, which were about 140 denier ~-twist textur-ized nylon. The chain stitch yarns 12 were of similar denier, but S-twist. As shown in FIGURE 1, there were five chain-stitch yarns and four float yarns per full repeat of the pattern, The filling yarn pattern was that shown in FIGURES 1 and 3, where each of the cotton filling yarns 16 and 18 interlace with each of the chain-stitch warp yarns 12~ but merel~ pass over or under the float yarns 14 without being interlaced therewith. There were 18 filling picks per inch of bandage length.

Since the bandage as formed on -the machine has a degree of stress due to the tensions applied to the various yarns during process-ing, it was conditioned by exposing it to moist steam at 80C for about two minutes, after which it was dried. The weight of the dried and relaxed bandage was 117 grams per s~uare yard, 140 grams per square meter.

The finished bandage had an air porosity of over 700 cubic feet of air per square foot per minute at 0.5 inches pressure, as tes-ted on the Frazier Air Permeability apparatus. At 100% elongation, the bandage had 9 picks, or filling yarns, per inch. The filling cover factor was therefore 2 (9/square root of yarn size.
20). This is a very low cover factor, characteristic of open-mesh netting. Coupled ~ith the fuzzy, dispersed configuration of the texturized warp yarns, it insures a breathability and comfort in use that is not found in conventional elastic bandages.

In addition to being light weight and comfortable to wear, the bandages of this invention are absorbent, and may be washed and sterilized without degradation. Since they contain no rubber or synthetic elastomeric material, they may be used in cases where elastomer yarns in contact with the skin gi~e rise to an allex-~LlS~

genic reaction.

It will be appreciated by those skilled in the art that, unlikethe production of woven bandages on a narrow loom, the knitted bandages of this invention may be produced on a wide flat-bed machine, and that a plurality of bandages r of varying widths if desired, may be yroduced in a single machine operation using a tie~
in yarn between individual bandages if necessary, said yarn being readily removed subsequently by an unraveling operation.

The above description of the bandage is to be regarded as exemplary only, and other sizes of yarn and knitting patterns may be utilized without departing from the spirit of the invention.

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A light weight, porous elastic bandage which comprises a first set of texturized parallel warp yarns formed into chain-stitch loops, a second set of texturized float yarns parallel to said first set of yarns but not connected thereto, and multiple sets of non-texturized, inelastic filling yarns deployed in a regular and repetitive pattern across portions of said first and said second sets of warp yarns, said sets of filling yarns being interlaced with the loops of at least some of said chain-stitch warp yarns, and said sets of filling yarns passing alternately over and under said set of float yarns without being interlaced therewith.

2. The bandage according to claim 1 wherein the number of chain-stitch warp yarns and float warp yarns are substan-tially equal.

3. The bandage according to claim 2 wherein the chain-stitch yarns and float yarns alternate across the width of the bandage.

4. The bandage according to claim 1 wherein the total number of both the chain-stitch warp yarns and the float warp yarns contains a substantially equal number of yarns of S-twist and yarns of Z-twist.

5. The bandage according to claim 2 wherein the float yarns and the chain-stitch yarns are of opposite twist.

6. The bandage according to claim 1 wherein said filling yarns interlace with the loops of each of said chain-stitch yarns.

7. The bandage according to claim 1 in which the texturized warp yarns are of heat-set thermoplastic material.

8. The bandage according to claim 1 in which each of the multiple sets of filling yarns is deployed over from five to nine warp yarns.