CA1325148C - High elastic modulus bandage - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A high elastic modulus, cohesive bandage comprising partially extended spaced aligned elastic yarns sealed between two thin nonwoven fibrous webs by means of a polymeric binder is disclosed. The bandage provides joint support without imposing undue constriction. A method of supporting suspensory ligaments and flexor tendons in the leg of a horse is also described.

Description

132~ 8 HIGH ELASTIC MODULUS BANDAGE

This invention relates to elastic shirred materials and the use thereof as a support bandage.
It is well recognized in the art that shirred fabrics can be made by stretching a sheet of rubber, holding it in a stretched condition, 10 adhering a fabric to each side, and removing the restraining force to pucker or shirr. U.S. Patent No. 22,038 describes material consisting of threads of India rubber stretched and bonded between two laminae of cloth and then permitted to retract, thereby causing puckering of the fabric to provide the desired shirred effect. U.S. Patent No. 3,575,782 15 describes an elastic shirred web product consisting of partially extended spaced aligned elastic yarns sealed between two thin porous gathered nonwoven fibrous webs, or between a web and a non-porous film, by means of a soft flexible polymeric coherent binder.
Elastic shirred web materials have been used in commercially 20 available products such as Coban~ and Vetrap~, both available from the Minnesota Mining and Manufacturing Company. Vetrap~ is sold for use on horses and other animals, and is covered by above-mentioned U.S. Patent No. 3,575,782. It is used primarily for decorative purposes and as a rundown bandage. It is also used as a holding wrap 25 for applying compresses, medicated pads and the like; and for providing support for injuries.
The present invention also involves elastic shirred sheet material but has several advantages over that taught in the art. The material of the invention has a higher elastic modulus, is more cohesive and is 30 more durable.
~- - In one preferred form, the product of the invention r,i;.s;
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,, -`` 132~1~8 has utility as an equine bandage. The banda~e is durable enouqh to be used as a rundown bandage without the addition of rundown patches which are ~enerally necessary when currently available bandages are used. The hi~her elastic modulus of the banda~e allows it to provide additional joint support, yet surprisin~ly it has been found that it does not unduly constrict circulation.
In one preferred method of the invention, a banda~e of the invention is applied to the front le~ of a horse in a serles of fi~ure 8's extendin~ below the fetlock joint as low as the coronary band, and above the fetlock joint as hi~h as the knee. This provides support for the suspensory li~aments and flexor tendons, thereby reducin~ the potential for injury due to hyperextension of the fetlock joint.

SUMMARY OF THE INVENTION
The present invention describes a cohesive elastic banda~e comprisin~ a series of spaced elastic yarns between coextensive thin nonwoven fibrous cover webs, the banda~e bein~ uniformly impre~nated throu~hout and bonded to~ether in a unified structure with a polymeric binder having a basis wei~ht at least equal to the basis - 20 wei~ht of the cover webs. The yarns are maintained under tension in the resultin~ uniform structure. The yarns are from about 550 to about .~ 1700 denier and are uniformly spaced at about 10 to 36 yarns per inch of width. The banda~e is further characterized by havin~ an elastic modulus F26 value of from about 0.3 to about 2 pounds per inch of - 25 width, an elastic modulus F50 value of from about 0.5 to about 3 pounds per inch of width, an elastic modulus F76 value of from about 0.7 to 4 pounds per inch of width, and an elastic modulus Floo value of from about 1 to 6 pounds per inch of width.
A method of supportin~ the suspensory li~aments and .., x ' :"' ..,..:,~
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- 132~148 flexor tendons in the leg of a horse is also described.

BRIEF DESCRIPTION ()F THE DRAWINGS
Figure 1 is a schematic representation showin~ the manufacture of the elastic sheet material. Figure 2 is a representation in plan view of a portion of the product.

DETAILED DESCRIPTIOI~I OF THE INVENTION
As shown in Fi~ure 1, elastic yarns 10 from a beam 11 are unwound under tension provided by brake 12 and throu~h comb 14.
Thin nonwoven fibrous webs 15 and 17, from supply drums 16 and 18, respectively or directly from the forming machine, if desired, are brought into contact with the yarns and with each other between squeeze rolls 19 and 20, the latter dipping into a pan 21 containing a fluid binder mixture 22. The composite web passes directly into a dryin~ oven 24 and thence between pull drums 25 and 26. The web next passes around idler roll 27, between heating platens 28 and 29, around pull drum 30 and idler roll 31, and is wound up to form stock roll 32.
. 20 Squeeze rolls 19 and 20 rotate at a considerably yreater surface speed than does beam 11, and the yarns 10 are accordingly stretched a corresponding amount. This stretch is maintained by operating pull drums 25 and 26 and turn-around drum 27 at approximately the same speed compared with rollers 19 and 20. Pull drum 30 and windup drum 32, however, are again operated at a slower speed to permit shrinkage of the web as it passes between the heater plates 28 and .~ 29. The composite web 34, which is smooth as it reaches the roll 27, becomes increasin~ly puckered or shirred as it passes through the - heatiny zone, the result being further indicated in Figure 2.
The heat supplied by the platens 28 and 29 is sufficient to cause considerable fuming of the sheet .

132~1~8 material and to relax the structure sufficiently to permit the elastomeric yarns to retract and produce the desired de~ree of puckerin~ or shirrin as controlled by the speed of the pull drum 30. The temperature may be re~ulated by adjustin~ both the ener~y input to the platens and the 5 distance between the platens and the web. In a typical installation for producin~ a web havin~ a finished width of 32 inches before trimmin~, the electrically heated platens are each 15 inches hi~h and 40 inches wide, and are spaced between six and nine inches from the web. A
- thermometer placsd adjacent the web between the platens re~isters about 200-250F. The duration of the heat treatment may be re~ulated, for a ~iven iength of platen, by adjustin~ the speed of travel of the web, sufficient time bein~ provided to permit retraction of the web to the desired de~ree. The platens are maintained at a temperature sufficient to keep the web taut durin~ the shrinkin~
operation between rolls 27 and 30 at the speed indicated but not so high as to cause deterioration of the web as evidenced by excessive fuming and discoloration thereof. The length of the relaxed web after retraction will be within the ran~e of about one-third to about two-thirds the fully extended len~th. ThE elastic yarns are initially stretched . 20 to a len~th of about three to five times their fully relaxed len~th, and are permitted to relax only partially durin~ the puckerin~ step.
Nevertheless, the shirred product is dimensionally stable, the heat treatment serving to provide an effective degree of heat-setting or stabilizin~, and neither shrinks nor expands when allowed to stand at normal temperatures and under no external stress; and it returns to such dimensions when first stretched and then permitted to retract.
The thin fibrous matts are conveniently prepared on a ~arnettin~
machine or preferably on a "Rando-Webber" machine. Matts of polyester or rayon staple fibers or mixtures are preferred. The fibers are desirably of about `:

`` 132~1~8 2 inch denier and about 0.75 to 1.5 inch in length, and the matt is about 0.25 to 0.50 oz./sq. yd. or about 5-10 Ib. per 320 sq. yd.
These very thin matts are fra~ile and flimsy, but show surprising strength when combined in composite structures of the type and in the 5 manner hereinabove indicated. Where the flimsiness of the untreated matt presents inordinate difficulties in handling, the matt as first formed may be reinforced by lightly treatin~ with a compatible bonding agent. As an example, the reinforced matt may consist of 90 parts by weight of polyester staple fibers and ten parts of polyethyl acrylate, the 10 latter being applied at the forming machine by saturating with a dilute emulsion of the polymer, removing the excess between squeeze rolls and drying in an oven.
Concentrated natural rubber latex is preferred as the impregnatin~ and bonding or unifying medium. Other elastomers or 15 blends of elastomers having similar properties may be used. The dried rubbery residue, although presenting a sli~htly tacky feel, does not adhere to the skin, but coherently bonds ~o itself with sufficient force to hold the contacting layers together against reasonably high shearin~
stresses. The impregnating and bonding materials may be used 20 without further modification, but will ordinarily be blended with pi~ments or other visual modifiers.
In an illustrative example, the varns 10 or 700 denier spandex ~; ~ spaced 18 ends per inch of width and each of the webs 15 and 17 consists of.a polyester matt (0.3 oz./yd.2). Centrifuged natural rubber 25 latex at 60% concentration lavailable from the E. P. Lambert Company or from Stein Hall, Inc.) serves as the fluid binder mixture 22. The beam 11 has a surface speed of 39 feet per minute, whereas the speed at rolls 19 and 20 is 91 ft./min., that at rolls 25, 26 and 27 is 86-88 ~` ft./min., and that at rolls 30 and 32 is 40 ft./min. The resulting sheet 30 material was X

,, 132~1~8 slit into bandages 4 inches wide and 5 yards lon~. This material is referred to as Example 1 in the discussion below.
In a second illustrative example, the yarns 10 are 1680 denier spandex spaced 10 ends per inch of width and each of the webs 15 and 17 consists of polyester matt 10.3 oz./yd.2). Centrifuged natural rubber latex at 60% concentration serves as the fluid binder mixture 22. The beam 11 has a surface speed of 45 feet per minute, whereas the speed at rolls 19 and 20 is 83 ft./min., that at rolls 25, 26 and 27 is 84-87 ft./min., and that at rolls 30 and 32 is 40 ft./min. This material is referred to as Example 2 in the discussion below.
In a third illustrative example, the yarns 10 are 1680 denier ; spandex spaced 18 ends per inch of width and each of the webs 15 and 17 consists of a polyester matt (0.3 oz./yd2). Centrifuged natural rubber latex at 60% concentration serves as the fluid binder mixture 22. The beam 11 has a surface speed of 60 ft./min., that at rolls 25, 26 and 27 is 92-95 ft./min., and that at rolls 30 and 32 is 54 ft./min.
This material is referred to as Example 3 in the discussion below.
The physical characteristics of banda~es of Examples 1-3 the invention were compared with those of Vetrap~. The characteristics of cohesive strength, elastic modulus, and amount of latex solids were ,, j compared. The results are summarized in Table 1. The banda~e of Example 1 of the invention was found to be more cohesive than Vetrap~, perhaps due to the hi~her latex content of the banda~e of Example 1 of the invention Ithe bandages of Examples 2 and 3 of the invention were not tested for cohesive strength). Significant differences in elastic modulus were seen. The Fn values show that the bandages of the invention exert a hi~her compression force in the usable ran~e of 25% to 100% elon~ation while still maintainin~ the ability to - 132~

stretch an additional 50% while in use without exerting an unduly high compressive force which could constrict circulation and cause physical damage to a horse's leg.
This performance has been borne out in repeated field trials 5 where horses le~s have been wrapped with the bandage of Example 1 by various trainers using varied techniques followed by normal race activity. The bandage has provided support without imposin~ undue constriction and has shown good durability.

~- The cohesive strength of the bandages was measured on an Instron Tensile Tester usin~ the following procedure. The 1" by 1"
facings of two aluminum T-section blocks were covered with double - coated tape. One of the T-blocks was placed, with the adhesive side 15 down, on a sample of the bandage. The edge of the block was kept parallel to the yarns in the sample. The sample was cut around the edges of the T-block with a sharp razor blade. This procedure was ;~ ~ repeated until there were four layers of sample attached to the T-block.
All four layers had the same side towards the face of the block and the 20 yarns were running in the same direction. With the ed0es of the blocks and sample in perfect alignment, the face of the second T-block was . superimposed a~ainst the first. The resulting specimen was placed in a jig and compressed with a 20 pound weight for 60 seconds. The specimen was hooked to the hangers on the tensile machine and the 25 cohesive stren~th was recorded.

TENSILE AND ELONGATION MEASUREMENTS
This procedure uses a Instron Constant Rate of Extension Tensile Tester to determine Fn modulus values. The Fn modulus value is the 30 force required to elongate the test specimen a certain percent ~n). The machine conditions :
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were set at a gauge length of 50 mm, a crosshead speed of 250 mm/min and a chart speed of 250 mm/min. A 1" wide by 8" long sample was razor cut from a banda~e. In order to minimize the incidence of jaw breaks, masking tape tabs were applied so that one 5 tab was located in each jaw of the apparatus. The sample was clamped between the jaws, the crosshead was started and the stress plot was recorded, and the Fn values were calculated from the stress plot. The Fn values stated in the instant examples are an average of the values determined according to this procedure for at least ten . 10 samples of each example. The Fn vaiues stated in the claims are an avera~e of the values determined accordin~ to this procedure for ten samples of each example. This procedure is derived from ASTM*D
882-80a.

~ Bandage samples were ozonized to break down the rubber and ; then rinsed in heptane. The heptane extracts were then analyzed by ~ infrared spectroscopy.

.:-' ~ American Society for Testing and Materials.

132~1~8 Elastic Modulus Vetra~n' Exam~le 1 Exam~le 2 Bxam~le 3 (Ib./inch width) F25 0.08 0.45 0.56 0.93 F50 0.25 0.76 0.90 1.52 10 P~5 0.52 1.03 1.20 2.11 F,oo 1.87 1.64 1.56 2.80 F,25 3.04 2.32 1.98 4.01 Fl50 9.11 4.67 2.58 6.91 ~` CohesiveStrength 17.7 24.1 . (lb./inch2) Latex Solids 0.67 0.77 (g/24 inch2) Vetrap~ is made with 10 ends/inch of 280 denier yarn. Example - 25 1 is made with 18 ends/inch of 700 denier yarn as discussed ` - previously. Example 2 is made with 10 ends/inch of 1680 denier yarn - as discussed previously. Example 3 is made with 18 ends/inch of ~ 1680 denier yarn as discussed previously.

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Claims (7)

1. A cohesive elastic bandage comprising a series of spaced elastic yarns between coextensive thin nonwoven fibrous cover webs, the bandage being uniformly impregnated throughout and bonded together in a unified structure with a polymeric binder having a basis weight at least equal to the basis weight of the cover webs, said yarns being maintained under tension in said unified structure, and wherein said elastic yarns are from about 550 to about 1700 denier and are uniformly spaced at about 10 to 36 yarns per inch width; said cohesive elastic bandage further being characterized by having an elastic modulus F25 value of from about 0.3 to about 2 pounds per inch of width, an elastic modulus F50 value of from about 0.5 to about 3 pounds per inch of width, an elastic modulus F75 value of from about 0.7 to about 4 pounds per inch of width, and an elastic modulus F100 value of from about 1 to about 6 pounds per inch of width.

2. The bandage of Claim 1 wherein said elastic yarn is about 700 denier and is uniformly spaced at 18 yarns per inch of width.

3. The bandage of Claim 1 wherein said elastic yarn is 1680 denier and is uniformly spaced at 18 yarns per inch of width.

4. The bandage of Claim 1 wherein said elastic yarn is 1680 denier and is uniformly spaced at 10 yarns per inch of width.

5. The bandage of claim 1, wherein said polymeric binder comprises natural rubber latex.

6. The use of a bandage as claimed in any one of claims 1 to 5 for supporting the suspensory ligaments and flexor tendons in the leg of a mammal.

7. The use of a bandage as claimed in any one of claims 1 to 5 for supporting the suspensory ligaments and flexor tendons in the leg of a horse.