CA2173227A1 - Compacted fabrics for orthopedic casting tapes - Google Patents

Abstract

The present invention provides an article, comprising: a fabric sheet which has been compacted using a heat shrink yarn; and a curable or hardenable resin coated onto the fabric sheet. The present invention involves compacting a fabric sheet to impart stretchability and conformability to the fabric while minimizing undersirable recovery forces. Suitable fabrics for compacting are fabrics which comprise fiberglass fibers which are capable of first being compacted and then being heat set or annealed in the compacted state. The article may be in the form of an orthopedic bandage and may optionally contain a microfiber filler associated with the resin.

Description

WO 95111~47 2 17 3 2 2 7 PCT/US9~/09884 C(~mp~te~l Fabrics for Orthopedic ~ Tapes Field of the Invention This invention relates to sheet m~tPri~l~ coated with a curable or hardenable polymeric resin. More particularly, this invention relates to a curable or hardenable resin coated sheet m~tPri~l useful in prep~rin~ an orthopedic bandage.

Background of the Invention Many different orthopedic casting m~tPri~ls have been developed for use in the immQbili7~tinn of broken or otherwise injured body limbs. Some of the first casting m~tPri~ls developed for this purpose involve the use of plaster of Paris bandages con~i~ting of a mesh fabric (e.g., cotton gauze) with plaster incorporated into the openings and onto the surface of the mesh fabric.
Plaster of Paris casts, however, have a number of ~tt~nd~nt disadv~nt~ges, including a low strength-to-weight ratio, resulting in a finishedcast which is very heavy and bulky. Furthermore, plaster of Paris casts typically dicinte~rate in water, thus making it nece~ry to avoid bathing, showering, or other activities involving contact with water. In addition, plaster of Paris casts are not air permeable, thus do not allow for the circulation of air beneath the cast which greatly f~cilit~tP-s the evaporation and removal of moisture trapped between cast and skin. This often leads to skin maceration, irrit~tion, or infection. Such disadvantages, as well as others, stimulated l~s~rcll in the orthopedic casting art for casting m~tPri~l~ having improved pl~ellies over plaster of Paris.
A si~nific~nt advancement in the art was achieved when polyisocyanate prepolymers were found to be useful in formulating a resin for orthopedic " casting m~t~ri~ls, as disclosed, for example, in U.S. Pat. No. 4,502,479 (Garwood et al.) and U.S. Pat. No. 4,441,262 (Von Bonin et al.). U.S. Pat.
No. 4,502,479 sets forth an orthopedic casting m~teri~l comprising a knit fabric which is made from a high modulus fiber (e.g., fiberglass) impregnated WO 95/11647 PCTIUS94/0988~ --~ ~322 7 -2-with a polyisocyanate prepolymer resin which will form a polyurea.
Orthopedic casting materials made in accordance with U.S. Pat. No.
4,502,479 provide significant adv~ncement over the plaster of Paris orthopedic casts, including a higher strength-to-weight ratio and greater air permeability.However, such orthopedic casting materials tend not to permit tactile manipulation or p~lp~tion of the fine bone structure beneath the cast to the extent possible when applying a plaster of Paris cast. In this regard, knit fiberglass materials are not as compressible as plaster, and tend to mask the fine structure of the bone as the cast is applied, e.g., the care provider may be limited in "feeling" the bone during reduction of the fracture.
Fiberglass backings have further disadvantages. For example, fiberglass b~k;n~ are comprised of fibers which have essentially no elongation. Rec~ e the fiber elongation is essPnti~lly nil, glass fabrics do notstretch unless they are constructed with very loose loops which can deform upon application of tension, thereby providing ~LIelclling of the fabric.
Knitting with loosely formed chain stitches imparts extensibility by virtue of its system of interlocking knots and loose loops.
To a greater extent than most knitted fabrics, fiberglass knits tend to curl or fray at a cut edge as the yarns are severed and adjacent loops unravel.
Fraying and raveling produce lln~ightly ends and, in the case of an orthopedic cast, frayed ends may interfere with the formation of a smooth cast, and loose, frayed ends may be sharp and irrit~ting after the resin thereon has cured. Accordingly, frayed edges are considered a distinct disadvantage in orthopedic casting tapes. Stretchy fiberglass fabrics which resist fraying are disclosed in U.S. Pat. No. 4,609,578 (Reed). Thus, it is well known that fraying of fiberglass knits at cut edges can be reduced by passing the fabric through a heat cycle which sets the yarns giving them new three-dimen~ion31 configurations based on their positions in the knit. When a fiberglass fabric which has been heat-set is cut, there is minim~l fraying and when a segment of yarn is removed from the heat-set fabric and allowed to relax, it curls into the crimped shape in which it was held in the knit. Accordingly, at the site of - 2~ ~3~327 a cut, the severed yarns have a tendency to remain in their looped or knotted configuration rather than to spring loose and cause fraying.
In procPccing eYt~ncihle fiberglass fabrics according to U.S. Pat. No.
4,609,578 (Reed), a length of fabric is heat-set with ecsenti~lly no t~ncinn 5 The fabric is often wound onto a cylin~ric~l core so large batches can be ,rocessed at one time in a single oven. Care must be taken to avoid applying undue tension to the fabric during wind-up on the knitter which would distort the knots and loops. To prevent applying tension to the fabric during winding, the winding operation is preferably performed with a sag in the fabric as it is 10 wound on the core.
AlLell.aLi\~ely, U.S. Pat. No. 5,014,403 (Buese) describes a method of making a ~Lle!cllable orthopedic fiberglass casting tape by knitting an elastic yarn under tension into the fiberglass fabric in the length direction, rele~cingthe tension from the elastic yarn to compact the fabric and removing the 15 elastic yarn from the fabric. The resulting fabric must then be collected under low tension in order to preserve the compact form. Likewise, any subsequent heat setting must also be performed under low tension. However, to avoid exce~Aing this low tension is difficult and as a result substantial amounts of the comr~tion imparted by the elastomeric yarn may be lost during 20 subsequent processes. The elastic yarn is removed by a combustion plucess which may cause localized areas of high temperature which may degr~le the fiberglass yarns. The physical ~ru~elLies of glass fibers are adversely affectedwhen subjected to temperatures in excess of about 540 C. ~ting fiberglass fabrics to le~.J~ Lures above about 540 C should be avoided, as subjecting 25 the fiberglass to temperatures of greater than about 540 C can weaken the fiberglass yarns in the fabric, which may result in reduced strength of casts made from such fabrics.
From the folcgoing, it will be appreciated that what is needed in the , art is an orthopedic casting m~t~.ri~l which has both the advantages of plaster 30 of Paris, e.g., good moldability and palpability of the fine bone structure, and the advantages of non-plaster of Paris materials, e.g., good strength-to-weight ratio and good air permeability. In this regard it would be a ~ignifi~nt WO 95/11647 2 17 3 2 2 7 PCTtUS~4/0988~ --advancemPnt in the art to provide such a combination of advantages without actually using plaster of Paris, thereby avoiding the inherent disadvantages of plaster of Paris outlined herein. It would be a further advancement in the art to provide such non-plaster of Paris orthopedic casting m~t~ri~lc which have as good or better pr~ellies than the non-plaster of Paris orthopedic casting m~teri~ls of the prior art. Such orthopedic casting m~teri~l~ and methods for r~aling the same are disclosed and cl~imP~ herein.

R~l~te~l Aprlir~t~
Of related interest are the following U.S. Patent Applications, filed on January 25, 1993 by the ~ccign~ of this invention: "Mech~nic~lly Compacted Fabrics for Orthopedic Casting Tapes" - Serial No. 08/008,161; and "Microcreping of Fabrics for Orthopedic Casting Tapes" - Serial No.
08/008,751; and copending U.S. Patent Application filed on October 25, 1993 by the ~ccign~qe of this invention entitled "Wet Compacting of Fabrics for Orthopedic Casting Tapes"; Serial No. 08/142,573, and "Vibration Compacted Fabrics for Orthopedic Casting Tapes", Serial No. 08/142,177.

Summary of the Invention The present invention provides an article comprising a compacted fiberglass fabric sheet and a curable or hardenable resin coated onto the fabricsheet. The fabric sheet is compacted using a heat shrinkable yarn (hereinafter "heat shrink yarn") and is optionally heat set thereby removing the heat shrink yarn and providing extensibility to the fabric. The article may be in the forrn of an orthopedic bandage. The present invention also provides an article comprising a compacted fiberglass fabric sheet, a heat shrink yarn, and a curable or hardenable resin coated onto the fabric sheet. The heat shrink yarn in this embodiment remains in the fabric, thereby providing resistance to lengthwise extension, yet yields in response to a tensile force thereby providing a controlled extension of the fabric.

~ WO 95/11647 ~ 1 7 3 2 2! 17 i PCT/US94/09884 _5 _ Brief Des~ lion of the Drawings FIG. l is a two bar Raschel knit in which bar one performs a simple chain stitch and bar two performs lapping motions to lay in yarn.
FIG. 2 is a three bar Raschel knit in which bar one ~e,rol"~s a simple 5 chain stitch and bars two and three perform lapping motions to lay in yarn, and wl-c~ein bar three i11u~tr~tes the lay in of a heat shrink yarn.
FIG. 3 is a four bar Raschel knit in which bar one performs a simple chain stitch and bars two, three and four ~lrolm lapping motions to lay in yarn, and wherein bar four illustrates the lay in of a heat shrink yarn.
FIG. 4 is a depiction of a three bar Raschel knit in which bar one ""s a simple chain stitch, bar two performs lapping motion to lay in yarn, and bar three p~lrOlllls lapping motions to lay in a heat shrink yarn. Thebars are depicted in a overlapping view.
FIG. 5 is a depiction of a three bar "latch hook" Raschel knitter in which four needles are shown knitting four chain stitches and two guidebars providing lay-in yarns. For the purposes of this invention, one might ~lt~."~ ely employ a "compound needle" Raschel knitter which is not shown.

Detailed Desw;~lion of the Invention The present invention relates to orthopedic casting m~trri~1~ and methods for prepa,illg and using such orthopedic casting materials, wherein the m~teri~1~ comprise a fiberglass backing or fabric which is impregn~trd with a curable or hardenable liquid resin. In particular, the fabrics employed in the present invention have important characteristics and physical properties which allow the fabrics to be made highly extensible.
One e1em~nt of this invention is a flexible sheet upon which a curable or hardenable resin can be coated to reinforce the sheet when the resin is cured or hardened thereon. The sheet is preferably porous such that the sheet is at least partially impregnated with the resin. Examples of suitable sheets are 30 knit fabrics comprised of inorganic fibers or materials such as fiberglass. The sheet may alternatively be referred to as the "scrim" or the "b~rkin~

2~L73227 6 The present invention involves compacting a fabric sheet using a heat shrink yarn to impart stretchability and conformability to the fabric while minimi7ing lmdPsir~hle recovery forces.
Suitable fabrics, after comp~tion, have impo~ t char~terictics and S physical pro~l Lies which allow the fabrics to be loaded with resin to the extent needed to provide proper strength as an orthopedic casting mateAal, while providing ne~eCc~ry porosity as well as improved extensibility leading to improved conformability, tactile manipulability, moldability, and palpability.
Several important criteria for choosing a fabric which will provide the characteristics nP~ess~ry for purposes of the present invention include: (1) lengthwise e~tPncibility and conformability after compaction, and the related characterictics of moldability, tactility, and palpability once the fabric has been resin in.l)re~ tP~; (2) resin loading capacity; and (3) porosity. It is important that each of these parameters be carefully controlled in providing fabrics which will s-lccescfully form orthopedic casting m~tPri~l.c (e.g., casts having high strength and good layer-to-layer l~min~tion strength) within the scope of the present invention.
Extensibility is important from the standpoint that the fabric must be extensible enough along its length, i.e., in the elongated direction, so that the result~nt orthopedic casting m~teri~l can be made to subst~nti~lly conform to the body part to which it is applied. Materials which are not sufficiently eYtPncihle in the elongated direction do not conform well to the body part when wrapped therearound, often resnlting in undesirable wrinkles or folds in the material. On the other hand, the extensibility of the fabric in the elongated direction should not be so high that the material is too stretchy, resulting in a material structure which may be deformed to the extent that strength is subst~nti~lly reduced.
For purposes of the present invention, the coated fabric, after compaction and after being coated with a curable liquid resin, should have from about 10% to about 200% extensibility in the elongated direction when a 2.63 N tensile load or force is applied per l cm wide section of the fabric, and preferably from about 25% to about 100% extensibility in the elongated ~173227 direction when a 2.63 N tensile load or force is applied per 1 cm wide section of the fabric, and more preferably from about 35% to about 65% extensibility in the elongated direction when a 268 gram load or force is applied across a 1 cm section of the fabric.
Although not nearly as critir~l, it is also desirable that the fabric employed have some e ~tencibility along its width, i.e., in the direction transverse to the elongated direction. Thus although the fabric may have from O~o to 100% extensibility in the transverse direction, it is presently preferable to use a fabric having from about 15~ to about 30% extensibility in the transverse direction when a 2.63 N tensile load or force is applied per 1 cm wide section of the fabric. The compaction process described herein prinçip~lly imparts e~rten~ihility in the elongated direction. However, it is anticipated that one might compact a fabric in the elongated direction and in the transverse direction, thereby imparting biaxial extensibility.
lS The fabrics of the present invention, after compaction, although stretchable, are preferably not overly elastic or resilient. Fabrics which are overly elastic, when used as backings for orthopedic bandages, tend to cause undesirable constriction forces around the wrapped limb or body part. Thus, once the resin impregnated fabric has been stretched and applied around a body part, the stretched m~t~ri~l preferably maintains its shape and does not resort back to its unstretched position.
The resin loading capacity or ability of the fabric to hold resin is important from the standpoint of providing an orthopedic casting material which has sufficient strength to efficaciously immobilize a body part. The surface structure of the fabric, including the fibers, interstices, and apertures, is very important in providing proper resin loading for purposes of the present invention. In this regard, the interstices between the fibers of each fiber bundle must provide sufflcient volume or space to hold an adequate amount of resin within the fiber bundle to provide the strength necessary; while at the same time, the apertures between fiber bundles preferably remain snfficiently unoccluded such that adequate porosity is preserved once the cast is applied.
Thus, the interstices between fibers are important in providing the necess7,ry ~i7322 ~ -8-resin loading capacity, while the apertures are important in providing the nP~e~s~ry polosily for the fini~hed cast. However, a balancing of various parameters is needed to achieve both proper resin loading and porosity. The coated fabric should have preferably between about 6 and 70 opening~ (i.e., 5 ape,lu~s) per square cm, more preferably between about 10 and S0 openings per square cm, and most preferably between about 20 and 40 openings per square cm when measured under a tensile load of 2.63 N/cm width. As used herein an "opening" is defined as the area defined by ~ rent wales and in-lay members. The number of openings per unit area is therefore determined 10 by multiplying the number of wales by the number of courses and dividing by the area.
As used herein, a "compacted" fiberglass sheet is one in which eYten~ihility is imparted to the fabric due to the structural overlapping of succe~ive loops and/or the structural relaxation of loops by the "heat shrink 15 yarn" compaction processes described herein. The compaction process is believed to impart exten~ihility to the fabric by "compacting" the loops of the knit as described herein. Typically, when a fabric is knitted the inside surfaces of two ~(ljaçent rows of loops are in contact or nearly in contact and the loopsare distorted in the lengthwise direction (e.g., in the shape of an oval). This 20 contact and/or distortion is the result of the fabric being under tension while the knit is being formed. Each successive row of loops (i.e., chain stitches) is, in effect, formed against the prec~ling row of loops. The compaction process of the present invention imparts fabric compaction by overlapping adjacent rows of loops (i.e., to a "non-contacting" position) and/or relaxing the 25 str~ined loops to a lower stress (e.g., more circular) configuration and optionally setting or ~nn~ling the fabric in the compacted form. Fl~ten$ihility is imparted to the fabric due to the overlap of the rows and/or the greater ability of the more circular loops to be deformed. When tension is again applied to the fabric the loops can return to their original "cont~cting"
30 position, i.e., the position they occupied when originally knit.
Fiberglass knitted fabrics with good extensibility are achievable with two common knitting methods: Raschel and tricot. Raschel knittin~ is ~73227 ~ WO 95/11647 PCTJUS94/09884 g_ described in "Raschel Lace Production" by B. Wheatley (published by the National Knitted OUL~1Wear ~OC;~t;On, 51 Madison Avenue, New York, N.Y. 10010) and "Warp Knittin~ Production" by Dr. S. Raz (published by Heidelberger Verl~g~n~t~t und Druckerei GmbH, Hauptstr. 23, D-6900 ~ berg, Germany). Two, three and four bar Raschel knits can be produced by regulating the amount of yarn in each stitch. Orthopedic casting tape fabrics are generally two bar Raschel knits although extra bars may be employed. Factors which affect the extensibility of fiberglass Raschel knits arethe size of the loops in the "chain" stitch, especi~lly in relation to the 10 fii~meter(s) of the yarn(s) which passes through them, and the amount of a loose yarn in the "lay-in" or "laid-in" stitch(es). If a chain loop is formed and two strands of lay-in yarn pass through it which nearly fill the loop, then the loop resists deformation and little stretch will be observed. Conversely, if thelay-in yarns do not fill the loop, then application of tension will deform the 15 loop to the limits of the lay-in yarn diameter and stretch will be observed.
Typical bar p~tttorn~ for the knit fabric substrates of the present invention are shown in the drawings.
FIG. 1 is a two bar Raschel knit in which bar one performs a simple chain stitch and bar twp performs lapping motions to lay in yarn.
FIG. 2 is a three bar Raschel knit in which bar one pelroll.ls a simple chain stitch and bars two and three perform lapping motions to lay in yarn, and wherein bar three illustrates the lay in of a heat shrink yarn.
FIG. 3 is a four bar Raschel knit in which bar one performs a simple chain stitch and bars two, three and four perform lapping motions to lay in 25 yarn, and wherein bar four illustrates the lay in of a heat shrink yarn.
FIG. 4 is a depiction of a three bar Raschel knit in which bar one ~elrulllls a simple chain stitch, bar two performs lapping motion to lay in yarn, and bar three performs lapping motions to lay in a heat shrink yarn. The bars are depicted in a overlapping view.
30 FIG. 5 is a depiction of a three bar "latch hook" Raschel knitter in which four needles are shown knitting four chain stitches and two lay-in WO 95/11647 21 7 3 ~ 2 7 PCT/US94/09884 -10- .
itrhes For the purposes of this invention, one might alternatively employ a "compound needle" Raschel knitter which is not shown.
It should be understood that the above bar patterns may be modified.
For example, Fig 2 may be modified by employing fewer or more heat shrink 5 lay-in yarns. Alternatively, the heat shrink yarn may be knitted in one or more of the chain stitches of the fabric or more than one heat shrink yarns may be laid in a single chain stitch.
For orthopedic casting m~t~ri~l, the fabric selected (preferably fiberglass), in addition to having the extensibility requirement noted above, 10 should be of a suitable thickness and mesh size to insure good penetration ofthe curing agent (e.g., water) into the roll of resin-coated tape and to providea fini~hed cast with adequate strength and porosity. Such fabric parameters are well-known to those skilled in the art and are described in U.S. Pat. No.
4,502,479.
When the casting m~t~ri~l is a fiberglass fabric, suitable heat shrink yarns are made of fibers which shrink and optionally combust at le,l,~eratures lower than the degradation temperature of the inorganic fibers (e.g., glass fibers) of the fabric. Preferably the ~hrink~ge and combustion temperatures of the heat shrink yarn are less than or equal to the temperature commonly used for heat setting fiberglass yarns. More preferably the shrinkage temperature of the heat shrink yarn is between about 70 C and 300 C. Most preferably the ~hrink~e lellly~ ture of the heat shrink yarn is between about 100 C and 200 C. Preferably the combustion temperature of the heat shrink yarn is between about 200 C and 540 C. More preferably the combustion lelllpeldture of the heat shrink yarn is between about 300 C and 500 C.
~e~tin~ the fabric to temperatures above about 540 C should be avoided as subjecting the fiberglass to telllpe.~tures of greater than about 540 C can weaken the fiberglass yarns in the fabric which may result in reduced strength of casts made from such fabrics.
Suitable heat shrink yarns for use in the present invention include yarns which shrink when heated at a temperature less than the degradation temperature of the inorganic fabric and which when present in a sufficient 21~3227 ~ WO 95/11647 PCT/US94/09884 quantity are capable of comp~ting the fabric. Preferred heat shrink yarns comprise fibers having at least 10 % shrink~e when heated (and when tested using a Testrite MK4 tester as described in Example 1). More preferably, the yarn has at least 20 % shrink~ge and most preferably at least 30 % chrink~ge.
One class of suitable heat shrink yarns are partially or highly orit~ntPd polymer yarns which shrink when heated above their glass transition dlu,e but below their melting tel-lL~ldture. In general, the physical ~-opelLies of polymer fibers (e.g., polyester fibers) is strongly ~ffect~d by fiber structure. For example, to provide the heat shrink property some degree 10 of crystallinity is ~lerell~d.
Suitable polymer fibers for use as the heat shrink yarn include both mu?tifil~mP~t and monofil~ment (staple or continuous fil~ment) yarns which are optionally tPxtllri7P~1 and fully or partially oriented. The yarns may be comprised of semi-crystalline polymers such as polyester, polyamide, 15 polyethylene and copolymers or graft copolymers of these. Preferred polymer fibers for use as the heat shrink yarn include polyester and polyethylene.
Partially oriented polyester is presently most ~l~felled.
The heat shrink yarn(s) may be knit into the fabric either as a lay-in or as a chain stitch. Preferably, the heat shrink yarn is knit into the fabric as a20 lay-in stitch. The escenti~l requirements of a heat shrink yarn are that it be capable of knitting with the fabric yarn and that it compact the fabric.
Therefore, when the heat shrink yarn is shrunk and optionally combusted, e.g., through application of heat, the fabric remains present in the form of a compacted, optionally heat set fabric. The heat shrink yarn is preferably knit 25 into the fabric such that the knit is compacted at least 10%, more preferably at least 14 5'0, and most preferably at least 18 5~.
When the heat shrink yarn is present as laid-in yarns it is preferably knitted through a single wale. This embodiment is illustrated, for example, in Figure 2. In that figure, a third bar is depicted knitting a heat shrink yarn 30 across a single chain stitch (bar 1). Additional lay-in yarns are knitted into the fabric using bar 2. In this manner maximum lengthwise compaction may be achieved as the heat shrink yarn is shrunk. Alternatively, the heat shrink yarn WO95/11647 2 ~ 7 3221 PCTIUS94/098X4 may cross more than one wale. It is believed that this embodiment will produce a fabric with biaxial compaction.
As previously mentioned, the heat chrink~hle yarn should be positioned in the knit so as to minimi7e the amount required and maximize the force S ~en~r~ted during contraction. If the yarn is placed in as a wale in addition to the fiberglass wales (i.e., as an additional wale since after d~ci7ing some wales would need to be present) a cignific~nt amount of organic m~tPri~l is added which could result in a brittle tape after heat tre~tm~ont If the yarn is placed as a lay-in and maximum lengthwise comp~ction is desired then the 10 yarn is preferably laid in across a single needle in order to ensure that most of the chrink~ge force of the laid-in yarn is used to compact the tape in the length direction.
The heat shrink yarn may be knitted through each wale (not shown in Fig 2) or through fewer than all the wales (as shown in Fig 2). Notably, there 15 need not be a heat shrink yarn for every wale. The heat shrink yarn need only be present in the fabric in an amount s-~fficient to give the desired comp~ction to the fabric when the yarn is heat shrunk. It has been found that knitting the heat shrink yarn through every fourth or fifth wale is preferred.
Having too many heat shrink yarns increases the potential for undesirable 20 localized heating of the fiberglass during the optional combustion step. Having too few heat shrink yarns results in uneven compaction or inadequate compaction. The exact number of heat shrink yarns needed will depend upon the fabric weight and knit pattern employed, the weight and shrink L.r~ellies of the heat shrink yarn employed, and the desired amount of compaction.
The heat shrink yarn may also be in the form of a chain stitch yarn.
When the heat shrink yarn is knitted in the form of a chain stitch it is preferable to lay in noncombustible yarns (e.g., fiberglass yarns) across the heat shrink chain stitch yarn and thereby connect adjacent noncombustible chain stitches. Thus, if the heat shrink chain stitch is later optionally removed 30 when heat setting the fiberglass, the fabric will m~int~in its integrity.
It may also be beneficial to vibrate the fabric during the compaction process to improve the uniformity of the compaction. This is particularly ~ WO 95/11647 ~17 3 2 2 ~ PCT/US94/09884 important when the heat shrink yarns are spaced apart and not knit through every wale. Suitable vibration methods are described in copending U.S.
Patent Application "Vibration Comp~ct~l Fabrics for Orthopedic Casting Tapes", Serial No. 08/142,177.
In proce~cil-g the knitted fiberglass fabric of the present invention, a length of fabric is optionally, and preferably, heat-set while the fabric is in a comp~cted form. Preferably, the fabric is comp~çted and then wound onto a cylin~lric~l core so large batches can be heat set at one time in a single oven.Care must be taken to avoid applying undue tension to the fabric (after 10 combustion of the heat shrink yarn and before the heat set has occurred) which would distort the knots and loops.
A continuous heat-setting process may also be used in which a length of fabric is first compacted by heat shrinking the heat shrink yarn and then thecompast~d fabric is placed on a moving conveyor system and passed through 15 an oven for a sufficiçnt time and temperature to achieve heat setting of the fabric. ~ltern~tively, one may use the same oven to both compact the fabric and heat set the fiberglass yarns provided that sufficient time is allowed for the compaction process prior to melting of the heat shrink yarn. Notably, when short lengths of fabric are so processed the ends of the heat shrink yarn 20 should be held in relation to the ends of the fiberglass yarns so as to causecompaction. Otherwise the heat shrink yarns may merely slip against the fabric as they shrink and not cause compaction of the knit fabric.
The heat-setting step may be ~lrol.~led in a number of conventional ways known to the art. In heat-setting a small piece of fiberglass fabric, e.g.,25 25 cçntim~terS of tape, in a single layer, a te."l e,~ "e of 425 C for three minutes has been found to be s--fficient Equivalent setting at lower tempeldlures is possible, but longer time is required. In general, batch processes require a longer residence time at the selected temperature due to the mass of glass fabric which must be heated and the need to remove all 30 traces of sizing m~teri~l which may -n~çsir~bly color the final fabric.
The optimum heat-setting process described above is sufficient in most cases to remove the sizing from the fabric. However, the process of the WO 95/11647 PCT/US9410~884 ~
~17322~ 4_ present invention may also be pr~tiçeA using partially heat-desized or a ch~mic~lly-desized fabric. Ch~omic~l desi7ing processes are described in U.S.
Pat. Nos. 3,686,725; 3,787,272; and 3,793,686. Heat clesi7ing processes are described in U.S. Pat. No. 4,609,578.
In general, to completely desize the fiberglass tape and not leave any visible residue it is ne~es~ry to heat the tape to a tel"pe,dtul~ between 370 and 430C, more preferably between 400 and 430C. The closer you get to 430C the shorter the cycle and more efficient the operation. Although the tape could be cleaned at higher tçmrç~tllres, this may cause permanent degradation of the fiberglass fabric. For eY~mple, when the telllpe,dtul~ of thefabric exceeAc 480C and especially when the telllpeldture exceeds 540C the tensile strength of the knit decreases very rapidly. When the tape is exposed to telllpeldtul~s over 590C it becomes very brittle and wrapping a cast using normal tension is precluded. A ~lc~r~lled heat ~eci7ing cycle raises the oven telllpeldture to about 430C and maintains that temperature until the tape is clean (e.g., about 6-8 hours in a recirculating oven). However, obtaining this result is somewhat complicated since the tape's temperature is affected by both the heat of the oven and the heat of combustion resulting from burning the sizing and/or any organic yarn (i.e., the heat shrink yarn) which may be present.
Controlling the exotherm from organic material in the knit is e~çnti~l and can be accomplished most easily and economically by limiting the total amount of added organic m~teri~l (e.g., sizing and heat shrink yarn) which must be removed. In order to knit a fiberglass yarn without excessive damage a sizing is preferably present. Preferably the amount of sizing utilized is the - minimum level n.-cess~ry to prevent damage during knitting. A plerellt;d amount of sizing on fiberglass is between 0.75 and 1.3556 (based on weight of the fabric). In addition to this sizing, in order to compact the tape, a heat ~hrink~hle yarn is added to the fabric. Since this yarn adds subst~nti~lly to the total level of organic m~teri~l in the fabric it is important to limit the amount added. This can be accomplished by several methods.

W O 95/11647 2 i 7 3 2 2 7 PCTrUS94/09884 First, one may limit the number of heat shrink yarns used. Initial trials at comp~cting fabrics using the method of the present invention placed the heat shrink yarn in every wale. This amount of heat shrink yarn is believed to be Imne~es~y and undesir~hle due to the resultin~ high 5 exothermic le"~pel~tu,e during de~i~ing. Preferably the knit has a heat ~hrink~hle yarn in-laid across the tape only in wales spaced 2-6 neeAl~s apart.
Most preferably the knit has a heat ~hrink~hle yarn in-laid across the tape onlyin wales spaced 3 to 6 needles apart. Normally, the spacing is uniform across the web but since the pl~rerl~d pattern used crosses only a single needle it can10 be varied without mo-lific~tion to the knitting machine.
Second, one may decrease the denier of the heat shrink yarn.
Preferably, the lowest denier yarn which has sufficient shrink force to compact the tape should be used. For ~lefe,led fiberglass fabrics the preferred heat shrink yarns are about 100 to 500 denier, more preferably about 200 to 300 denier.
Finally, it has been observed that the jumbo's winding tension can greatly influence the exothermic temperature rise due to combustion and thelcrore adversely affect web integli~y. In general, jumbos wound under higher tension tend to reach a lower peak temperature and have a greater web integrity than those wound more loosely. It is believed that the organic content of more tightly wound jumbos burn more slowly and therefore the jumbos have lower peak internal lel"l~el~tures. While not intending to be bound by theory, this result is believed to be due to oxygen starvation within the jumbo. Within a jumbo (i.e., away from the surface of the roll) the availability of oxygen is controlled by the diffusion rate into the jumbo.
Careful control of the roll's permeability to oxygen can be utilized to control the rate of combustion of the organic m~t~ri~l.
The fabric is preferably cooled prior to application of the resin. The resin selected to apply to the heat-set fabric is dictated by the end-use of the 30 product. For orthopedic casting m~t~ , suitable resins are well-known and described for example, in U.S. Pat. Nos. 4,376,438; 4,433,680; 4,502,479;
and 4,667,661 and U.S. Patent Application Serial No. 07/376,421. The WO 95/11647 ~ ` ` ; . PCT/US94/09884 2~.73227 16 presently most prefei.ed resins are the moisture-curable isocyanate-termin~te~i polyurt;~ e prepolymers described in the aforementioned p~tPntc.
Alternatively, one may employ one of the resin systems described herein. The amount of such resin applied to the fiberglass tape to form an orthopedic S casting m~te~i~l is typically an amount sufficient to constitute 35 to 50 percent by weight of the final "coated" tape. The term "coated" or "coating" as used herein with respect to the resin refers gPnPric~lly to all conventional processes for applying resins to fabrics and is not intended to be limiting To insure storage stability of the coated tape, it must be properly 10 packaged, as is well known in the art. In the case of water-curable isocyanate-termin~tPA polyurethane prepolymer resin systems, moisture must be e~clllde~. This is typically accomplished by sealing the tape in a foil or othermoisture-proof pouch.
In one embodiment of the present invention, a fiberglass fabric which 15 further comprises a plurality of heat shrink yarns is knit according to the process described herein, compacted by heat shrinking the aforemPntinned yarns, and then heat set in the compacted form while also removing the heat shrink yarns. The comp~cted fabric is then coated with a curable resin. There are many advantages to this process over conventional knitting processes.
20 First, unlike traditional uncompacted knit fiberglass fabrics, the fabric produced by this method has increased extensionability. Furthermore, the heat shrink yarn, when in its shrunken state, provides support to the fabric during subsequent collecting operations (such as when winding a large jumbo roll) thereby preventing undesirable extension of the fabric prior to it being heat 25 set. The ~mi~hPd fabric of this embodiment comprises only noncombustible yarns and retains its compacted form as a result of the heat setting of the fiberglass yarns.
In a second embodiment of the present invention, a fiberglass fabric which further comprises a plurality of heat shrink yarns is knit according to 30 the process described herein and compacted by heat shrinking the aforementioned yarns. The compacted fabric is then coated with a curable resin. There are many advantages to this process over conventional knitting WO 95/11647 ~ 1 7 3 2 2 7 PCT/US94/09884 p,oce~es. First, unlike traditional uncomp~t~l knit fiberglass fabrics, the fabric produced by this method has increased extensibility. The heat shrink yarn, when in its shrunken state, provides support to the fabric during subsequent winding operations (such as when winding a roll during the production process) and unwinding operations (such as when the fabric is applied to the patient) thereby preventing undecir~ble extension of the fabric prior to it being applied. The finiched fabric of this embo~lim~o-nt retains itscompacted form principally as a result of the heat shrink yarns and is extensible only when the heat shrink yarns are plastically deformed (e.g., by stretching them). That is to say, the fiberglass fabric may be extended, as needed, when it is applied to the patient by stretching (and thereby pl~ctir~llydefoln~ g) the heat shrunken yarns. In contrast to stretching an elastic yarn, plastically deforming a heat shrink yarn avoids undesirable rebound of the fabric which could cause undesirable conctriction forces. Rather, the plastically deformed heat shrink yarns retain their deformed state when the tensile force is removed.
Suitable fabrics, after compaction, are compacted to between about 30 and 90 percent of their original ~iimPncion. More preferably, the fabric is compacted to between about 50 and 80 percent of its original dimension.
Most preferably, the fabric is compacted to between about 60 and 75 percent of its t)rigin~l dimension.
The curable or hardenable resins useful in this invention are resins which can be used to coat a sheet mat~ri~l and which can then be cured or hardened to reinforce the sheet m~teri~l. For example, the resin is curable to acrosclink~d thermoset state. The ~rere-led curable or hardenable resins are fluids, i.e., compositions having viscosities between about 5 Pa s and about 500 Pa s, preferably about 10 Pa s to about 100 Pa s.
The resin used in the casting m~tPri~l of the invention is preferably any curable or hardenable resin which will satisfy the functional requirements of 30 an orthopedic cast. Obviously, the resin must be nontoxic in the sense that it does not give off cignific~nt amounts of toxic vapors during curing which may be harmful to either the patient or the person applying the cast and also that it WO 95/11647 2 ~ 7 3 ~ 2~i PCT/US9411~9884 -18- .
does not cause skin irritation either by chemic~l irritation or the generation of excessive heat during cure. Furthermore, the resin must be sl-fficiently reactive with the curing agent to insure rapid hardening of the cast once it is applied but not so reactive that it does not allow s--Mciçnt working time to S apply and shape the cast. Initially, the casting m~t~ri~l must be pliable and formable and should adhere to itself. Then in a short time following completion of cast application, it should become rigid or, at least, semi-rigid,and strong to support loads and stresses to which the cast is subjected by the activities of the wearer. Thus, the m~t~ri~l must undergo a change of state 10 from a fluid-Iike condition to a solid condition in a matter of minutes.
The pr~ ed resins are those cured with water. Presently pre~lred are urethane resins cured by the reaction of a polyisocyanate and a polyol such as those disclosed in U.S. Patent No. 4,131,114. A number of classes of water-curable resins known in the art are suitable, incl~l-ling polyurethanes, lS cyanoacrylate esters, epoxy resins (when combined with moisture sensitive catalysts), and prepolymers termin~t~d at their ends with trialkoxy- or trihalo-silane groups. For example, U.S. Pat. No. 3,932,526 discloses that 1,1-bis(perfluoromethylsulfonyl)-2-aryl ethylenes cause epoxy resins cont~ining traces of moisture to become polymerized.
Resin systems other than those which are water-curable may be used, although the use of water to activate the hardening of an orthopedic casting tape is most convenient, safe and f~mili~r to orthopedic ~ulgeons and m~Aiç~l casting personnel. Resin systems such as that disclosed in U.S. Patent No.

3,908,644 in which a bandage is impregn~ted with difunctional acrylates or 25 methacrylates, such as the bis-methacrylate ester derived from the conden~ti~ n of glycidyl methacrylate and bisphenol A (4,4'-isopropylidenediphenol) are suitable. The resin is hardened upon wetting with solutions of a tertiary amine and an organic peroxide. Also, the water may contain a catalyst. For example, U.S. Patent No. 3,630,194 proposes an 30 orthopedic tape impregn~tç1 with acrylamide monomers whose polymeri7~tion is initi~ted by dipping the bandage in an aqueous solution of oxidizing and reducing agents (known in the art as a redox initiator system). The strength, WO 9!5/11647 ~ 1 7 3 2 2 7 PCT/US94/09884 rigidity and rate of hardening of such a bandage is subjected to the factors rlosed herein. Alternatively, hardenable polymer dispersions such as the aqueous polymer dispersion disclosed in U.S. Patent No. 5,169,698, may be used in the present invention.
Some presently more p.~re~l~d resins for use in the present invention are water-curable, isocyanate-functional prepolymers. Suitable systems of this type are disclosed, for example, in U.S. Patent No. 4,411,262, and in U.S.
Patent No. 4,502,479. P~efe~red resin systems are disclosed in U.S. Pat. No.

4,667,661 and U.S. Patent Application Serial No. 07/376,421. The following 10 disclosure relates primarily to the preferred embo~liment of the invention wherein water-curable isocyanate-functional prepolymers are employed as the curable resin. A water-curable isocyanate-functional prepolymer as used herein means a prepolymer derived from polyisocyanate, preferably aromatic, and a reactive hydrogen compound or oligomer. The prepolymer has suffici~Pnt 15 isocyanate-functionality to cure (i.e., to set or change from a liquid state to a solid state) upon exposure to water, e.g., moisture vapor, or preferably liquid water.
It is ~ref~lled to coat the resin onto the fabric as a polyisocyanate prepolymer formed by the reaction of an isocyanate and a polyol. Suitable 20 isocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, .~ u~c of these isomers, 4,4'-diphenylmeth~ne diisocyanate, 2,4'-diphenylmeth~ne diisocyanate, mixture of these isomers together with possible small qu~ntities of 2,2'-diphenylmethane diisocyanate (typical of commercially available diphenylmeth~ne diisocyanate), and aromatic polyisocyanates and their 25 mixtures such as are derived from phosgenation of the conden~tiQn product of aniline and formaldehyde. It is preferred to use an isocyanate which has low volatility such as diphenylmeth~ne diisocyanate (MDI) rather than a more volatile m~tçri~l such as toluene diisocyanate (TDI). Typical polyols for use inthe prepolymer system include polypropylene ether glycols (available from 30 Arco Chemic~l Co. under the trade name Arcor PPG and from BASF
Wyandotte under the trade name Pluracol~), polytetramethylene ether glycols (PolymegTY from the Quaker Oats Co.), polycaprolactone diols (Niax~ PCP

WO95/11647 ~,~7322~ PCTIUS94/0988 series of polyols from Union Carbide), and polyester polyols (hydroxyl termin~t~d polyesters obtained from ~stçrifit~tion of dicarboxylic acids and diols such as the Rucoflexsu polyols available from Ruco division, Hooker Chemi~l Co.). By using high molecular weight polyols, the rigidity of the 5 cured resin can be reduced.
An example of a resin useful in the casting m~tPri~l of the invention uses an isocyanate known as Isonate~ 2143L available from the Upjohn Compally (a ~ ure cont~ ing about 73% of MDI) and a polypropylene oxide polyol from Arco known as Arcol~ PPG725. To prolong the shelf life of the m~tPri~l, it is preferred to include from 0.01 to 1.0 percent by weight of benzoyl chloride or another suitable stabilizer.
The reactivity of the resin once it is exposed to the water curing agent can be controlled by the use of a proper catalyst. The reactivity must not be so great that: (1) a hard film quickly forms on the resin surface preventing further penetration of the water into the bulk of the resin; or (2) the cast becomes rigid before the application and shaping is complete. Good results have been achieved using 4-[2-[1-methyl-2-(4-morpholinyl)ethoxy]-ethyl]morpholine (MEMPE) prepared as described in U.S. Pat. No.
4,705,840, at a concentration of about 0.05 to about 5 percent by weight.
Poaming of the resin should be minimi7ed since it reduces the porosity of the cast and its overall strength. Foaming occurs because carbon dioxide is released when water reacts with isocyanate groups. One way to minimi7P
foaming is to reduce the concentration of isocyanate groups in the prepolymer.
However, to have reactivity, workability, and ultim~t~ strength, an adequate concentration of isocyanate groups is necessary. Although foaming is less at low resin contçnt~, adequate resin content is required for desirable cast char~teri~tics such as strength and resistance to peeling. One ~ti~f~ctory method of minimi7ing foaming is to add a foam suppressor such as silicone Antifoam A (Dow Corning), or Antifoam 1400 silicone fluid (Dow Corning) to the resin. It is especially preferred to use a silicone liquid such as Dow Corning Antifoam 1400 at a concentration of about 0.05 to 1.0 percent by weight. Water-curable resins containing a stable dispersion of hydrophobic 2~ ~3227 polymeric particles, such as disclosed in U.S. Patent Application Ser. No.
07/376,421 and laid open as Eulopeall Published Patent Application EPO 0 407 056, may also be used to reduce foaming.
Also included as presently more lJlef~ d resins in the present 5 invention are non-isocyanate resins such as water reactive liquid organornet~llic col"pou,lds. These resins are esreri~lly preferred as an ~ltPrn~tive to isocyanate resin systems. Water-curable resin compositions suitable for use in an orthopedic cast consist of a water-reactive liquid organom~t~llic compound and an organic polymer. The organometallic 10 compound is a compound of the formula (RlO)~MR2" X, wherein: each Rl is indeFendçntly a Cl-C10o hydrocarbon group, optionally interrupted in the backbone by 1-50 nonperoxide -O-, -S-, -C(O)-, or -N- groups; each R2 is 15 independently selected from the group con~i~ting of hydrogen and a Cl-C10o hydrocarbon group, optionally interrupted in the backbone by 1-50 nonperoxide -O-, -S-, -C(O)-, or -N- groups; x is an integer between 1 and y, inclusive; y is the valence of M; and M is boron, aluminum, silicon, or 20 tit~nitlm. The organic polymer is either an addition polymer or a cond~n~tionpolymer. Addition polymers are preferably utilized as the organic polymer con~tituent. Particularly useful addition polymers are those made from ethylenically unsaturated monomers. Commercially available monomers, from which such addition polymers can be formed, include but are not limited to, 25 ethylene, isobutylene, l-hexene, chlorotrifluoroethylene, vinylidene chloride, butadiene, isoprene, styrene, vinyl napthalene, ethyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, poly(ethylene oxide) monoacrylate, heptafluorobutyl acrylate, acrylic acid, methyl methacrylate, 2-dimethylaminoethyl methacrylate, 3-methacryloxy-30 propyltris(trimethylsiloxy)silane, isobutyl methacrylate, itaconic acid, vinylacetate, vinyl stearate, N,N-dimethylacrylamide, tert-butyl acrylamide, acrylonitrile, isobutyl vinyl ether, N-vinyl pyrrolidinone, vinyl azlactone, glycidyl methacrylate, 2-isocy~n~toethyl methacrylate, maleic anhydride, vinyl triethoxysilane, vinyl tris(2-methoxyethoxy)silane, and 3-W095111647 ~17 3 2 2 7 PCTrUS94/Q9884 (trim~thoxysilyl)propyl methacrylate. Polymers bearing hydrolyzable f~lnction~1ity are plefe~-ed. An acidic or basic catalyst may be used to ~ccPl~te the water cure of these compositions. Strong acid catalysts are yl~;f~lled.
S Also included as presently more preferred resins in the instant invention are alkoxysilane termin~ted resins, i.e., prepolymers or oligomers, having a number average molecular weight of about 400-10,000, preferably about 500-3,000. A polymer forms upon cont~tin~ the alkoxysilane tern in~ted prepolymer with water as a result of cond~n~tion of molecules of 10 this prepolymer with other molecules of the same prepolymer. Each molecule of the prepolymer or oligomer contains at least one hydrolyzable Le~ inal alkoxysilane group. Compounds of Formula I useful in the resin composi~ions of the present invention may contain one to six terminal alkoxysilane groups per molecule. Preferably, the alkoxysilane termin~t~d resin is a urethane-15 based resin, i.e., a prepolymer cont~ining -NH-C(O)-O-group(s), or a urea resin, i.e., a prepolymer cont~ining -NH-C(O)-N- group(s), or a resin cont~ining both urea and urethane groups.
The water-reactive alkoxysilane termin~t~ resin having at least one 20 hydrolyzable terminal alkoxysilane group per molecule is preferably a compound of the formula (Formula I):

Q - Y ~Rl--W~R 3 - S i ( O R4 ~ m~
- ( R5 ) ~ Z
- U

wherein:
Q is a polyol residue;
W is -NH-C(O)-X~22nq)- or -X-C(O)-NH-;

X is -N-, -O-, or -S-;

WO 95/11647 ~ 1 7 3 2 2 7 PCT/US94/09884 I

Y is -N-, -O-, -S-, carbamylthio (-S-C(O)-NH-), carbamate (-O-C(O)-NH-), or substituted or N-substituted ureido (-N(C(O)-NH-)-);
Rl is a substituted or unsubstituted divalent bridging Cl-C200 hydrocarbon group, optionally interrupted in the backbone by 1-50 nonpc;l~Aide-O-, -C(O)-, -S-, -SO2-, -NR6-, amide (-C(O)-NH-), ureido (-NH-C(O)~ ), carbamate (-O-C(O)-NH-), carbamylthio (-S-C(O)-NH-), uneubstitllted or N-substituted allophonate (-NH-C(O)-N(C(O)-O-)-), unsubstituted or N-substituted biuret (-NH-C(O)-N(C(O)-NH)-), and N-substituted isocyanurate groups;
R2 can be present or absent, and is selçcte~ from the group consisting of H and a substituted or unsubstituted Cl-C20 hydrocarbon group, optionally in~ u~Led in the backbone by 1-10 nonperoxide -O-, -C(O)-, -S-, -SO2-, or -NR6- groups;
R3 is a substituted or unsubstituted divalent bridging Cl-C20 hydrocarbon group, optionally inLellupled in the backbone by 1-5 nonperoxide -O-, -C(O)-, -S-, -SO2-, or -NR6- groups;
R4 is a C,-C6 hydrocarbon group or -N=C(R7)2;
each R5 and R7 is independently a Cl-C6 hydrocarbon group;
R6 is a H or a Cl-C6 hydrocarbon group;
n = 1-2andq = 0-l, withtheprovisothatwhenXisN, n + q = 1, and when X is S or O, n + q = 2;
u = the functionality of the polyol residue = 0-6, with the proviso that when u = 0, the compound of Formula I is Rl ~R3-Si(oR4) llL
- (R )~ ~ z m = 2-3; and z = 1-3.

-WO 95/11647 . ~ ' PCT/US94/09884 ~
2~7~227 It is to be understood that each "R3-Si(Rs)3 m(oR4)m" moiety can be the same or different. When used in Formula I, the Y and R' groups that are not symmPtric, e.g., amide (-C(O)-NH-) and carbamylthio (-S-C(O)-NH-) groups, are not limited to being bound to ~ cent groups in the manner in which these 5 groups are r~resented herein. That is, for example, if Rl is carbamate (represented as -O-C(O)-NH-), it can be bound to Y and W in either of two m~nnPrs -Y-O-C(O)-NH-W- and -W-O-C(O)-NH-Y-.
Herein, when it is said that "each" R5 and R7 is "independently" some substituent group, it is meant that generally there is no requirement that all R5 10 groups be the same, nor is there a lc~uile~l~ent that all R7 groups be the same.
As used herein, "substituted" means that one or more hydrogen atoms are repl~ed by a functional group that is nonreactive, e.g., to hydrolysis and/or condçn~ti~n and noninterfering with the formation of the cured polymer.
In ~r~relled m~t~ri~lc Rl is selected from the group con~i~ting of a substituted or unsubstituted Cl-C200 alkyl, a substituted or unsubstituted C,-C200 acyl, and groups of up to 50 multiples of a C3-Cl8 cycloalkyl, a C7-C20 aralkyl, and a C6-C,8 aryl. By this, it is meant that Rl can be a long chain cont~inin~, for example, up to 50 repeating C6-C,8 aryl groups. More preferably, R' is selected from the group con~i~ting of a substituted or unsubstituted C,-ClOO alkyl, a substituted or unsubstituted Cl-ClOO acyl, and groups of up to 30 multiples of a Cs-C8 cycloalkyl, and a C6-ClO aryl. Most preferably, R' is selected from the group con~i~ting of a C,-C20 alkyl, a Cl-C8 acyl, and groups of up to 5 multiples of a C5-C8 cycloalkyl, and a C6-C10 aryl.
In each of the preferred Rl groups, the backbone is optionally interrupted by 1-20 nonpero~ide -O-, -C(O)-, -S-, -SO2-, -NR6-, amide, ureido, carbamate, carbamylthio, allophonate, biuret, and isocyanurate groups.
In each of the more p.~ ;d Rl groups, the backbone is optionally interrupted by 1-10 nonperoxide -O-, -C(O)-, -S-, -SO2-, -NR6-, amide, ureido, carbamate, carbamylthio, allophonate, biuret, and isocyanurate groups.
In each of the most preferred R' groups, the backbone of each of the R' groups is not interrupted by any of these groups.

~ WO 95/11647 ~ PCT/US94/09884 t~ F~

In p~re"~d materials, each of R2 and R3 is independently selected from the group concicting of a substituted or unsubstituted Cl-C20 alkyl, a subsLi~uLed or unsubstituted C2-C,8 alkenyl, and groups of up to 10 multiples of a C3-C~8 cycloalkyl and a C6-CI8 aryl. More preferably, each R2 and R3 is S in~lepPndPntly selected from the group concicting of a substituted or unsubstituted Cl-C10 alkyl, a substituted or unsubstituted C2-C10 alkenyl, a C5-C8 cycloalkyl, and a C6-CI0 aryl. Most preferably, each R2 and R3 is indepPndently selected from the group concicting of a Cl-C6 alkyl, a C2 alkenyl, a C5-C8 cycloalkyl, and a C6 aryl. In each of the prefelled R2 and R3 10 groups, the backbone is optionally inL~,lupt~d by 1-5 nonpe,~ide -O-, -C(O)-, -S-, -SO2-, and -NR6- groups. In optimal resins, the backbone of each of the R2 and R3 groups is not int~"upted by any of these groups.
In preferred m~t~ri~l.c, each of R4, R5, R6, and R7 is independently a Cl-C6 alkyl group. More preferably, each is a Cl-C3 alkyl group. A single 15 prepolymer according to Formula I can be used in the resin composition of thepresent invention. Alternatively, a mixture of several different prepolymers according to Formula I can be used in the resin composition.
Optionally, the scrims of the present invention are coated with a resin which incorporates microfiber fillers. These plcfcll~d orthopedic bandages 20 enjoy many benefits, for example, resins which incorporate microfiber fillersexhibit: a dramatic increase in strength when coated on the backings of the present invention; an increased "early strength" upon curing; an improved durability and increased modulus; better layer-to-layer l~min~tion strength; a lower exotherm upon setting; and a lower effective resin cost co-"palt;d to 25 resins which do not incorporate such microfiber fillers. In addition, resin suspenci~-ns employing the microfiber fillers of the present invention exhibit generally very little increase in resin viscosity - thereby çnc-lring easy unwind of the casting bandage and good handling properties such as drapability.
Suitable microfibers for use in the present invention include those microfiber 30 fillers disclosed in U.S. Patent Application Serial No. 08/008,755.
In addition to the application of the present invention to the field of orthopedic casting tapes, other uses may include wlapl)ing and/or joining WO 95/11647 PCT/US~
~ 17 3227 -26-pipes, cables or the like; patching or bridging gaps to provide a surface for filling and repairs; etc.

The following ~Y~mples are offered to aid in underst~n-ling of the 5 present invention and are not to be construed as limiting the scope thereof.
Unless otherwise in-lic~, all parts and percentages are by weight.

EXAMPLES
Ring strength was measured as described in the following procedure. A
cylindric~l ring comprising 6 layers of the resin-coated material was formed by taking a roll of the resin-coated material from its storage pouch and immersing the roll completely in deionized water having a temperature of 15 about 27 C for about 30 seconds. The width of the ring formed was the same as the width of the resin-coated material employed, namely, 7.62 cm. The roll of resin-coated material was then removed from the water and the material was wrapped around a 5.08 cm ~ meter mandrel covered with a thin stockinet (such as 3M Synthetic Stockinet MS02) to form 6 complete uniform 20 layers using a controlled wrapping tension of about 45 grams per c~ntim~t~r width of material. Each cylinder was completely wound within 30 seconds after its removal from the water.
After 7 to 20 minutes from the initial immersion in water, the cured cylinder was removed from the mandrel. Ring strength was determined 24 25 hours after initial immersion in water, i.e., those samples were allowed to cure for 24 hours in a controlled atmosphere of 25 C + 2 C and 55% +
5% relative humidity prior to testing.
At the a~pr~ iate time each cylinder was then placed in a fixture in a commercial testing machine, e.g., an Instron 1122 instrument, and 30 co~ ~ssion loads were applied to the cylindrical ring sample along its exterior and parallel to its axis. The cylin-lric~l ring was placed lengthwise between the two bottom bars of the fixture (the bars being l.9 cm wide, 1.3 ~ WO 95/11647 PCT/US94/09884 ~ 73227 cm in height, and 15.2 cm long), with the bars spaced about 4 cm apart. The inside edges of the bars were m~chined to form a curved surface having a 0.31 cm radius. A third bar (0.63 cm wide, 2.5 cm high, and 15.2 cm long) was then centered over the top of the cylinder, also parallel to its axis. The S bottom or cont~ ting edge of the third bar was m~hin~d to form a curved surface having a 0.31 cm radius. The third bar was brought down to bear against and crush the cylinder at a speed of about 5 cm/min. The maximum force which was applied while crushing the cylinder was then recorded and divided by the width to yield the "ring strength," which in this particular instance is the "dry strength" (expressed in terms of force per unit length of the cylinder, i.e., newtons/cm). For each m~t~ri~l, at least 5 samples were tested, and the averdge peak force applied was then calculated and reported as the dry "ring strength. "
To measure the "wet ring strength", the same procedure was followed as for the "dry ring strength", except that after curing for 24 hours, the cylinder was then immersed in water at about 45 C for about 30 minutes, and then allowed to dry at room lel~lpeldture and pressure for about 15 minutes. The cylinder was then placed in the instrument and crushed as described hereinabove in order to determine the "wet ring strength" thereof.
To measure the "warm wet ring strength" of the cylinder, the procedure was followed exactly as set forth for the "wet ring strength"
measurement above, with the exception that the cylinder was placed in the fixture and crushed immediately after removal from the 45 C water bath and was not allowed to dry at all.
Ring del~min~tion was measured as described in the following procedure. A cylindrical ring comprising 6 layers of the resin-coated m~t~ri~l was formed by taking a roll of the resin-coated material from its storage pouch and immersing the roll completely in deionized water having a tenlpe,dture of about 27 C for about 30 seconds. The width of the ring formed was the same as the width of the resin-coated m~t~ri~l employed, namely, 7.62 cm. The roll of resin-coated material was then removed from the water and the material was wrapped around a 5.08 cm di~meter mandrel wo 95tl 1647 2 ~ 7 3 2 2 7 PcTruss~/09884 ~

covered with a thin stockinet (such as 3M Synthetic Stockinet MS02) to form 6 complete uniform layers using a controlled wrapping tension of about 45 grams per cçntimet~r width of m~tPri~l. A free tail of about 15.24 cm was kept and the balance of the roll was cut off. Each cylinder was completely S wound within 30 seconds after its removal from the water.
After 15 to 20 minutes from the initial immersion in water, the cured cylinder was removed from the mandrel, and after 30 minutes from the initial immersion in water its ~ min~tion strength was determined.
A determination of del~min~tion strength was done by placing the free tail of the cylindrical sample in the jaws of the testing machine, namely, an Instron Model 1122 m~chine, and by placing a spindle through the hollow core of the cylinder so that the cylinder was allowed to rotate freely about theaxis of the spindle. The Instron m~hine was then activated to pull on the free tail of the sample as a speed of about 127 cm/min. The average force required to dtol~min~t~- the wrapped layers over the first 33 centimeters of the cylinderwas then recorded in terms of force per unit width of sample (newtons/cm width). For each m~teri~l, at least 5 samples were tested, and the average del~min~tion force was then calculated and reported as the "del~min~tion strength. "
F~ml le 1 Shrink Yarns for Use in Compaction of a Fiberglass Knit ~ctinf~ Tape Most synthetic polymeric fibers exhibit some degree of ~hrink~ge when heated. In order to be useful in the present invention the heat shrink fibers should generate a sllfficient force and a sufficient displacement during their shrink~e to adequately compact the knit tape. Suitable heat shrink fibers are preferably capable of performing this compaction when present in an amount that can be successfully desized without causing excessive degradation of the fiberglass (e.g., present at a relatively low denier).
The percent shrink~ge and shrinkage force for the following commercially available yarns was measured as a function of temperature.
.

Table la Yarn Denier Composition Dupont'440-100-R02-52 440 ~llltifil~ment Polyester Dupont 220-50 220 Mlilltifil~ment Polyester ~çl~nese~ 90/36, T770 brt1 1/4 turn 90 MI1ltifil~m~nt Polyester Cel~n~se 100/33 100 ~ ltifil~mPnt Polyester Shakt;~e~ -306 340 Monofilamentpolyt;th~
0.009 401 1010 10A (LDPE) 0 Sh7~krs~ç5 re 283 283 Monofil~mPnt Polyester l Dupont, Fibers Div. Wilmington DE
2 ~el~nese Fibers, Cel~nese Chemical Co., New York, NY
' Shakespeare Monofil~ment Div., Columbia, S.C.

The data presented in Tables lb and lc was generated using a Testriten' MK IV Shrink~ge-Force Tester (available from Testrite Ltd., West Yolksllile, F.ngl~nd). Percent chrink~ge was measured using the following test method. The Testrite'X apparatus was prehe~te~ to the desired temperature range and a sample of yarn about 600 mm long was clamped at one end to the fixed jaw clamp and allowed to drape over the take up drum. A clip weight (1.78 gm) was ~tt~ched to the other end of the yarn and allowed to hang about 100 mm below the center of the drum. This weight is used primarily to take out the catenary from the sample. With the sample in position on the drum, the drum was rotated so the digital readout displays 0 (zero). The carriage assembly was then carefully pushed forward slowly into position in the heat zone. The heat will cause the sample to shrink and thus rotate the take up drum. Maximum chrink~ge of the sample at any given operating temperature is deemed to have taken place when the digital readout holds steady.
Shrink~ge force was similarly measured according to the following test. The Testrite~ apparatus was fitted with the load cell and jaw ~tt~chm~nt apparatus secured to the carriageway. The sample was secured to the fixed jaw clamp and draped over the take up drum as previously described. After removing the catenary from the sample (e.g., by h~n~ing a 1.78 gm weight from the free end of the sample) the load cell clamp was secured to the sample. The carriage assembly was then carefully pushed forward slowly into 7 2 1~ ~ 2 2 7 PCT/US94/09884 position in the preh~tt~A heat zone. The heat will cause the sample to shrink and thus apply tension to ~the load cell. Maximum ~hrink~ge force of the sample at any given operating temperature is then recorded.

Table lb Percent Shrink~ge for Various Yarns Temp DuPont ~ n~se C~l~n~seSh~k~s~æ~,e (C) 440 90 100 MX-306 180 14.5 10.5 11 220 24.5 20 16 WO 95/11647 ~17 3 2 2 7 PCT/USg4/09884 Table lb depicts the perce"~ge of shrinkage for various organic yarns which have been subjected to a heat cycle. As can be readily observed (and within the Ir~llp~,.t~lre ranges shown) the yarns generally exhibit more ~hrink~ge as they are heated to higher temperatures. Notably, the S "Sh~ke~ e MX-306" yarn (comprising a polyethylene polymer) exhibits its .~hrink~e at a lower temperature than the other yarns (which each comprise a polyester polymer).
Table lc Shrinkage Force For Various Yarns (N) 10 Temp Celanese' Celanese2 Celanese3 DuPont DuPont Shakespeare (C) 90 90 90 220 440 PX-301 140 0.3 0.7 1 0.7 0.7 150 0.3 0.6 1. 1 0.7 1.0 160 0.3 0.7 1. 1 0.8 1.0 170 0.2 0.8 1.1 0.8 1.1 180 0.4 0.7 1.2 0.7 1.5 1. 1 190 0.3 0.6 1.2 0.6 1.4 1. 1 200 0. 1 0.8 1.2 0.6 1.3 1.0 210 0.1 0.8 0.9 0.5 1.3 0.9 220 0.3 0.5 1.1 0.6 1.3 0.8 230 0.3 0.7 1. 1 1 .2 0.7 ' One yarn.
2 Two yarns.
25 3 Three yarns.
Table lc depicts the shrinkage force (Newtons) for various organic yarns. These yarns were preloaded with a weight of applo~imately 1.73 g prior to testing. The data for the Celanese 90 denier 36 fil~ment yarn shown 30 in Table lc incli~tes that the shrink force is generally proportional to the number of yarns used.

WO 95/11647 ., ~ PCT/US94/09884 ~ 7322~ -32-FY~mple 2 CQmp~ct;on of a Fiberglass Knit C~stin~ Tape Several of the yarns from Example 1 were inserted into a fiberglass knit structure and used to compact the knit structure. The yarns were placed in as a single needle lay-in in a fiberglass fabric with the following p~r~meterS Mayer Raschel 60 inch knitter (available from Meyer Textile M~-hinP,ry Corp., Greensboro, NC as HDRlOEHW ); 18 gauge (7.09 nPeAl~/cm); front runner length (chain stitch) 403.9 cm; back runner length (lay-in stitch) 355.6 cm; and middle runner length (shrink yarn lay-in stitch) 91.4 cm. Owens Corning fiberglass (available from Owens Corning, Aiken, SC as ECG 75 1/0 0.7Z 620) was used for both the front and back bar.
Heat shrink yarns were inserted into the knit using a third bar (i.e., the middle bar as previously described). As described below, the heat shrink yarns were not placed in every wale but were spaced into about every third or every sixth wale. The fabrics had the following physical plopellies: 10.4 cm width; 5.39 courses per cm; and 29.6 gm per meter length.
The fabric was heat shrunk using forced hot air and then wound up.
"Percent compaction" was measured by first marking off a known length of fabric and measuring the length after heat tre~tment Note that the m~rk~ off section was positioned in the middle of a longer piece of fabric in order to ensure that the heat shrink yarn would not slip during compaction. The percent compaction was calculated as:
initial length - shrunk length x 100 = percent compaction initial length WO95/11647 2~1 7~22 ~ PCT/US94/09884 , . ~

The following table s~mm~ri~es the results:

Table 2a Yarn Peak shrink Denier In-laid r~
S forcel, (N) evely: CQ~np~rti~. (%) Dupont 440 l.S 440 6 wales 15-18 %
Cçl~nese 90 1 end 0.4 90 102 ends 0.8 180 3 ends 1.2 270 6 wales 10-12 %
3 wales < 10 %
.Ch~ plo~re PX-301 1.1 283 6 wales > lS %
3 wales > 15 %
5CI '-,o.cr~re 1.5 340 6 wales 17-20 %

I Tested as described in Example 1.
20 The above data in~ t~s that in order to compact the fabric of this specific construction a force greater than about 1 N is desirable. Furthermore, the data suggests that a monofil~mçnt of equivalent denier a~eal~ to yield greater compaction than a mllltifil~mç~t yarn.

FY~mple 3 Effect of Winding Tension A 7.62 cm knitted fiberglass fabric cont~ining Dupont 440-100-R02-52 ml1ltifil~mçnt polyester shrink yarn was produced with the following parameters: Owens Corning fiberglass ECG 75 1/0 620; heat shrink yarn:
Dupont 440-100-R02-52 polyester; Mayer Raschel 229 cm 18 gauge (7.1 neetllPs/cm) knitter; knit pattern: 0/2, 2/0 (front bar); 0/0, 2/2 (middle bar);and 6/6, 0/0 (back bar); thread up: front and back- full, middle bar: single needle in-lay spaced every 6th wale; front runner length (fiberglass chain stitch ) 406 cm; back runner length (fiberglass lay-in stitch ) 274 cm; middle bar runner length (polyester heat shrink lay-in stitch ) 86.4 cm. Owens Corning fiberglass (available from Owens Corning, Aiken, SC as ECG 75 1/0 WO 95/11647 2 ~ 3 2 ~ PCT/US94/09884 620) was used for both the front and back bar. Note that the heat shrink yarn was in-laid 180 degrees out of phase with the fiberglass in-lay and across a single needle in an alternating pattem of: 1 wale in and the next five wales out. The exact middle bar threading was (1,5,1,5,1,5,1,5,1,4,1,5,1,5,1,5,1,5,1) where 1 inclic~tps a wale co~ ining a heat shrink yarn, 4 intlir~tes 4 wales without the heat shrink yarn, and 5 inrli~t~s S wales without the heat shrink yarn.
In order to determine the effect of wind-up tension on the le~ ule reached during de-~i7ing within a rolled up "jumbo" of fabric the following 10 e~periment was conducted.
A sample of approximately 27.4 meters of the knit structure was wound by hand into either a "tight" or a "loose" roll. The tight roll was produced by winding the knit as tightly as could be performed by hand without pl~tic~lly deforming the heat shrunk yarn. The loose roll was 15 produced by applying very little tension to the knit during windup. The tightly wound roll had a circumference of approximately 36.5 cm and the loosely wound roll had a circumference of approximately 44.0 cm. During the winding operation two small plastic tubes were inserted between the layers (as guides for inserting thermocouple sensors), the first approximately at the 20 middle of the roll diameter (i.e., near the core) and the second at approximately 1.3 cm from the outer edge. The plastic guides were removed prior to ~esi7ing. The rolls were placed in a forced air recirculating oven in separate cycles. The oven was brought up to 500 C and held for 8 to 10 hours at that temperature. The te-llp~-dture of the roll was recorded as a 25 function of time. Peak temperatures are shown below:

WO 95/11647 2 ~ 7 ~ 2 2 7 PCT/US94/09884 Table 3a pO~;ti~
Mid rollOuter lcm Roll Peak temp. Time Peak temp. Time S Tension (C) (Il~in.) (C) (n~in.) Tight 571 76 544 60 Loose 720 62 549 32 The data indicates that both rolls heated up ~i~nific~ntly higher than the oven temperature. The data also indicates that the loosely wound roll became ~ignific~ntly hotter in the center of the roll than the tightly wound roll. Thishigher temperature could lead to degradation of the fabric integrity. The loosely wound roll also reached its peak exotherm temperature more quickly than the tightly wound roll. Although not intending to be bound by theory, these results are believed to be in part due to the different amounts of oxygen available within the roll. The oxygen being necç~s~ry for the combustion of the heat shrink yarn and affecting the combustion rate.
Notably, an important advantage of using heat shrink yarns to impart compaction to a knit fabric is the ability to wind the knit fabric under tensionwhile not thereby removing the eYten~ibility.

FY~mple 4 Coated Fabric A 10.2 cm knit produced with the knitting parameters shown in Ex. 3 was heat shrunk in a tunnel oven at a temperature of 218 C. The fabric was observed to shrink approximately 15% during this heat tre~tment process. The 30 shrunken fabric was then wound into a fairly loose roll under low tension. Inorder to avoid sagging in the oven which would reduce the compactness of the fabric the roll was supported by wrapping fiberglass fabric through the aluminum core and around the exterior of the roll. This wrap served to support the weight of the fabric and prevent undesirable sagging.

WO 95/11647 21~ 3 2 2 7 PCT/US94/09884 The tape was heat set and cleaned in a recirculating hot air oven at 427 C for 8 hours. The heat set fabric was coated using a very low tension coater with the following isocyanate functional prepolymer resin:

Table 4a Chemical Manufacturer Eqwt. Wt.
Isonate 2143L Dow Chemic~l 144.7 57.7 pTol~-Pnes~llfonyl chloride Akzo 0.05 Antifoam DB-100 Dow Corning 0.18 Butylated hydroxytoluene Shell Chemi~l 0.48 Pluronic F-108 BASF 4.00 MEMPE 3M 1.15 PPG-2025 Union Carbidel1019.2521.22 LG-650 Union Carbidel85.49 5.67 Niax E-562 Union Carbide'1753.139.55 l Formerly available from Union Carbide now available from Arco Chemic~l Co., So. Ch~rlestc-wn, WV
The resin was coated on the 10.2 cm wide fabric produced as described above at a coating weight of 40% by weight. The product was rolled up on a 1.27 cm ~ meter polyethylene core into individual rolls approximately 320 cm long and the rolls were sealed in conventional moisture proof ~luminum foil 25 l~min~e pouches. The product was tested for the p~uL~ellies listed below according to the test methods described above. All values are the mean of 5 samples unless otherwise noted.

~17~227 W O 95/11647 . ~ . PCTrUS91 Table 4b Test Result Ring del~min~tionl 8.9 N/cm width Dry Strength 79.5 N/cm Wet Strength 42.0 N/cm Warm Wet Strength 25.6 N/cm 1 Three samples tore before a dt~l~min~tion value could be recorded. The result shown is an average of the two ~mrles that did not tear.
FY~mpl~ 5 Desize Cycle Opti~i7~tion In order to prevent degr~d~tion of the fabric it is important to keep the 15 Lenl~)t~dlUl'e in the jumbo as low as possible while still removing the yarn and combustion products completely. This experiment investigated various Lellll)eldture profiles in the oven cycle and the effect on intern~l fabric ures.
A 7.62 cm knitted fiberglass fabric co~ lg Dupont 440-100-R02-52 20 mllltifil~m~nt polyester shrink yarn was produced with the following parameters: Owens Corning fiberglass ECG 75 1/0 620; heat shrink yarn:
Dupont 440/100/R02/52 polyester; Mayer Raschel 229 cm knitter; 18 gauge (7.1 nee lle~/cm); knit p~ttern 0/2, 2/0 (front bar); 0/0, 2/2 (middle bar); and8/8, 0/0 (back bar); thread up: front and back- full, middle bar: single needle 25 in-lay spaced every 6th wale; front runner length (fiberglass chain stitch ) 406 cm; back runner length (fiberglass lay-in stitch) 368 cm; middle bar runner length (polyester heat shrink lay-in stitch) 96.5 cm. Owens Corning fiberglass (available from Owens Corning, Aiken, SC as ECG 75 1/0 620) was used for both the front and back bar. Note that the heat shrink yarn was in-laid 180 30 degrees out of phase with the fiberglass in-lay and across a single needle in an altern~ting pattern of: 1 wale in and the next five wales out. The exact middle bar threading was (1,5,1,5,1,5,1,5,1,4,1,5,1,5,1,5,1,5,1) where 1 indicates a WO 95tll647 . . PCTIUS94/09884 wale cont~ining a heat shrink yarn, 4 indicates 4 wales without the heat shrink yarn, and S in~ tt~s S wales without the heat shrink yarn.
The tape produced had a nominal 10.2 cm width and was wound up using a surface winder to a roll ~ meter of approximately 45.7 cm. The fabrics had the following physical prope,lies: 10.4 cm width; 5.79 courses per cm; and a weight of 16.6 gm per 240 courses.
The rolls were heat shrunk by passing the m~teriz/l as a single layer through a tunnel oven (approximately 1 meter in length) set at a temperature of 249 C at a speed of 96.5 cm/min. and ~up~ulled on a metal belt conveyor. After heat shrinking the tape was wound back up into roll form ûn a 7.62 cm ~ m~t~r aluminum roll. Individual rolls were heat set and cleaned in a small recirculated oven. The temperature cycles were varied and the t~l,lpe dture monitored using a set of thermocouples. Thermocouples were placed between layers of fabric at radial positions approximately 10, 50, and 90% of the roll length away from the core of the roll. The peak ~elllpel~tures reached at each of these points for each cycle are presented below:

Table Sa Run Oven operating conditions Peak temperature of roll Lell,p~ldl~lre cycle time at position in~lis~t~d (C! (hours! lo % 50 %

4 343C for 4 hours, then 427C for 4hrs 510 532 488 371C for 4 hours, then 427 C for 4hrs 468 496 438 After tre~tm~nt in the oven all the m~teri~ls were observed to be clean. Run S
is presently preferred.

WO 95/116472 ~ 7 3 ~ 2 7 PCT/US94109884 F.Ys-mpl~ 6 Effect of Heat Shrink Yarn on Web Integrity S~mples of heat set cleaned fabric similar to that described in Ex. 4 S were studied to determine whether there is any localized degradation of the fiberglass due to the added combustible heat shrink yarn (DuPont 440 yarn).
The fabric ~mple~ were sized by immersing the fabric in a 1 % aqueous solution of Triple Concent~dte DownyTM fabric softener (available from Proctor and Gamble Co., Cincinn~ti, OH). Samples were taken from the 10 midpoint of the roll which had been exposed to the operating conditions of Run #5 of Table Sa. Wales at selected positions across the width of the tape were removed and tested for tensile strength using an Instron model 1122 testing m~hine (Instron Corp., Park Ridge, IL). The average value of three sarnples is shown below in Table 6a.
Table 6a Wale number Tensile strength (N) ll 4.89 2 6.14 3 7.47 4 6.67 6.23 6 7.47 71 6.14 8 5.60 9 6.32 7.92 11 9.12 12 6.72 131 4.45 14 6.14 8.10 16 9.12 17 7.03 19' WO 95/11647 2 ~ 7 3 ~ ~ ~ PCT/US94/09884 I A heat shrink yarn was inserted at these wale positions.

The results clearly show that near the local vicinity of a heat shrink yarn the fiberglass yarns are degr~ed While not int~n~ling to be bound by theory, 5 this result is believed to be due to the fiberglass yarn having been exposed to a higher ]oc~1i7ed ~e~.~pe~ re caused by the combustion of the heat shrink yarn.
Similar knits to the above knit were produced except that the heat shrink yarn was replaced with three yarns in each position of the Cel~nPse 90 10 denier polyester shrink yarn (C90) or with a single yarn of the Shakespear PX-301 283 denier polyester monofil~ment (PX-301). Note that the PX-301 knit was only 7.62 cm wide and was not heat shrunk prior to heat setting. The individual wale tensile strengths for these fabrics is shown below in Table 6b:
Table 6b Wale number Tensile strength (N) n~se Shakespear 61 8.1 9.4 7 9.9 9.1 8 10.9 9.3 9 11.4 13.7 12.1 8.5 11 12.1 9.5 12' 9.0 9.2 13 9.3 8.5 14 8.9 11.4 8.1 9.0 16 12.2 11.7 17 9.0 9.0 8.4 8.8 1 A heat shrink yarn was inserted at these wale positions.
Note that the C90 sample shows loss of integrity near the local area around the heat shrink yarn. The PX-301 sample, however, does not show this effect WO 95/11647 ~ ¦ 7 3 ~ 2 ~ PCT/US~1J09~3 as clearly. Note that all of the wale strength values are significantly higher than for the knit cont~ining the Dupont 440 denier polyester.
A similar exper1m~-nt was cond~lcted using Sh~k~pe~r MX-306 polyethylene monofil~ment and no heat shrink yarn (control). For all 5 m~tPri~l~ a sample of fabric was also stretched in tensile in the Instron 1122and the load at which wale breakage occurred was recorded. A s~mm~ry of the data is given in the table below (values recorded in Newtons). All values are mean values of at least three trials.

Table 6c Test Control Dupont Celanese ~chal Psp~ar .~

(440d) (270d) (283d) (340d) Fabric Stretch Test 53-76 18-22 31-53 18-27 44-53' load at wale break Indiv. wale tensile 12.5 4.4 8.0 8.9 6.7 (wale w/ shrink yarn) Indiv. wale tensile 12.5 8.9 12.2 13.3 6.7 (wales wto shrink yarn) 25 ' Individual wales did not break before the fabric ripped at the clamp site.

The data clearly shows that the fabrics containing the lower denier polyester m~teri~l~ (C90 or PX-301) retain much more inleg.i~y than the fabric cont~inin~ the higher denier polyester heat shrink yarn (Dupont 440).
FY~mple 7 Fabric cQrnr~cte~3 with a n~-ltifil~ment POY yarn A 7.62 cm knitted fiberglass fabric con~ining Celanese partially 35 oriented yarn (hereinafter "POY") was produced with the following parameters: Owens Corning fiberglass ECG 75 1/0 620; heat shrink yarn:
C~l~n~se POY Style 661, 227 denier; Mayer Raschel 229 cm knitter; 18 gauge (7.0866 neerllç~/cm); knit pattern: 2/0,0/2 (front bar); 0/0,2l2 (middle WO 9~;/11647 PCT/US94/09884 ~7~227 bar); and 0/0,8/8 (back bar); thread up: front and back- full; middle bar:
single needle in-lay spaced every third wale; front runner length (fiberglass chain stitch ) 419 cm; back runner length (fiberglass lay-in stitch ) 338 cm;
take-up length per rack: 94 cm.
Owens Corning fiberglass (available from Owens Corning, Aiken, SC
as ECG 75 1/0 620) was used for both the front and back bar. Note that the heat shrink yarn was in-laid in phase with the fiberglass in-lay and across a single needle in an alt~rn~ting pattern of: 1 wale in and the next two wales out. The exact middle bar threading was (0101001001001001001001001001001001001001001001001001001010) where 1 indicates a wale cont~ining a heat shrink yarn and 0 indic~tPc wales without the heat shrink yarn.
A nominal 10.2 cm fabric was produced and wound up by hand. The fabric was heat shrunk by heating with saturated 10.3 N/cm2 steam. The fabric contracted about 12-15 %. Once desized the knit would have between about 40 and 45 % extensibility.
Various mo~ifi~tions and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not limited to theillustrative embo~limentc set forth herein.

Claims (20)

1. An orthopedic casting bandage comprising:
a compacted fiberglass knit fabric sheet, wherein said fabric comprises adjacent rows of overlapping loops of fiberglass yam, said fiberglass fabric being compacted using a heat shrink yarn; and a curable or hardenable liquid resin coated onto said compacted fiberglass fabric sheet.

2. An orthopedic casting bandage according to claim 1, wherein said coated fabric further comprises a heat shrunken yarn.

3. An orthopedic casting bandage according to claim 1, wherein said heat shrink yarn is selected from the group consisting of polyester, polyamide and polyethylene.

4. An orthopedic casting bandage according to claim 1, wherein said heat shrink yarn shrinks at a temperature between 70°C and 300°C.

5. An orthopedic casting bandage according to claim 3, wherein said heat shrink yarn is knit into said fabric as a lay-in.

6. An orthopedic casting bandage according to claim 3, wherein said sheet has from about 25% to about 75% extensibility in the elongated direction when a 268 gram load or force is applied across a 1 cm section of the fabric.

7. An orthopedic casting bandage according to claim 1, wherein said curable resin is selected from the group consisting of water-curable resins comprising awater-reactive liquid organometallic compound and an organic polymer, alkoxysilane terminated polyurethane prepolymer resins, and isocyanate-functional resins.

8. An orthopedic casting bandage according to claim 1, wherein said curable resin is a water-curable resin comprising isocyanate-functional resins.

9. An orthopedic casting bandage according to claim 3, wherein said fabric has between about 6 and 70 openings per square cm when under a tensile load of 2.63 N/cm width.

10. An orthopedic casting bandage according to claim 1, wherein said fabric was compacted to between about 30 and 90 percent of its original dimension.

11. An orthopedic casting bandage according to claim 1, wherein said fabric was compacted to between about 50 and 80 percent of its original dimension.

12. An orthopedic casting bandage according to claim 8, wherein said resin has a viscosity between about 10 Pa s and 100 Pa s.

13. An orthopedic casting bandage according to claim 3, wherein said heat shrink yarn has a denier between 100 and 500.

14. An orthopedic casting bandage according to claim 5, wherein said heat shrink yarn has a denier between 200 and 300.

15. A method of making an orthopedic casting bandage, comprising the steps of:
knitting a high modulus yarn and a heat shrinkable yarn to form a fabric;
heating said fabric to a sufficient temperature to cause said heat shrinkable yarns to shrink, thereby compacting said fabric; and coating said fabric with a curable or hardenable liquid resin.

16. A method according to claim 15, further comprising the step of:
heat setting said fabric thereby combusting said heat shrinkable yarn, and wherein said high modulus yarn comprises fiberglass.

17. A method according to claim 15, wherein said sheet has from about 25% to about 75% extensibility in the elongated direction when a 2.63 N
tensile load or force is applied per 1 cm wide section of the fabric.

18. A method according to claim 16, wherein said curable resin is selected from the group consisting of water-curable resins comprising isocyanate-functional prepolymers; water-curable resins comprising a water-reactive liquid organometallic compound and an organic polymer; and alkoxysilane terminated polyurethane prepolymer resins.

19. A method according to claim 16, wherein said resin has a viscosity between about 10 Pa s and 100 Pa s, and wherein said fabric is compacted to between about 20 and 50 percent of its original dimension.

20. A method according to claim 15, wherein said heat shrink yarn is knit into said fabric as a lay-in.