EP0599584A1

EP0599584A1 - Improved composite yarn with thermoplastic component

Info

Publication number: EP0599584A1
Application number: EP93309297A
Authority: EP
Inventors: Mark A. Andrews
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-11-25
Filing date: 1993-11-22
Publication date: 1994-06-01
Also published as: CA2103402A1; JPH06280121A; AU5195293A

Abstract

A composite yarn formed of melt-fusible thermoplastic fibers combined with selected other fibers and/or materials includes a containment barrier that encapsulates one or more core materials which may present a threat of contamination to workers and/or the environment. The composite yarn is comprised of a core which is covered in an adhesive layer of thermoplastic material which forms a containment barrier, combined with one or more and subsequent overlying layers of fibers wrapped or otherwise applied thereto in conventional yarn construction methods. The finished composite yarn is designed for knitting and weaving fabrics, or for otherwise forming cordage and non-woven products. The composite yarn also is utilized to produce end products such as cut-resistant apparel for environments where workers are exposed to possibly contaminated products or where core materials in the yarn can damage the end product of manufacture.

Description

BACKGROUND AND SUMMARY OF THE PRESENT INVENTION

The present invention is related to cut-resistant yarns and associated fabrics, cordage, or non-woven products which may be produced with the yarn. It is also related to static dissipative materials, materials reinforced for strength, and abrasion-resistant materials. Most particularly the present invention is related to the above products when containment of a core material is required due to the potential for hazard to the employee, product, or environment if the core material is exposed.
There has been significant activity in recent years with regard to the manufacture of yarns and fabrics for cut-resistant protective apparel. Many of these activities deal with the use of stainless steel wire in conjunction with various fibers to attain an optimal balance of cut resistance and flexibility, coupled with cost of production.
U.S. Patent No. 4,334,449 to Byrnes teaches the use of a longitudinally positioned wire strand covered with aramid, and the numerous resulting advantages of such wrapped wire. One advantage is superior cut resistance performance, when compared to gloves formed of pure aramid. Byrnes also describes improved knitability on a conventional glove knitting machine, and improved dexterity of a glove knitted from such a wire yarn.
U.S. Patent 4,470,251 to Bettcher extends the teachings of the above-mentioned Byrnes patent by illustrating two primary discoveries. First, that two or more smaller wire strands yield greater flexibility than one strand, while allowing a larger quantity of wire to be used, and the use of a longitudinally positioned fibrous strand incorporated with the wire strands further improves flexible movement. Second, Bettcher demonstrates that an outer covering formed of a polyamide such as nylon improves the comfort of the glove to the wearer.
Kolmes/Plemmons, in U.S. Patents numbered 4,838, 017 and 4,777,789, teach the wrapping of annealed stainless steel wire about a core fiber; wrapping the strands of wire in opposing directions and further increasing flexibility of the fabric while maintaining cut protection. Kolmes/Plemmons also documented a broad range of fibers that can be used in the core and outer wraps of the composite yarn.
The established prior art referenced here offers teachings that have improved the state of protective apparel. While each is representative of improvement, the present invention extends far beyond these prior teachings and demonstrates a novel and unique approach which solves a serious and heretofore unaddressed issue related to the manufacture of protective apparel. One previously unrecognized problem is the fact that in the use of wire composite yarns, the wire strands frequently break, puncturing the skin of the wearer, contaminating various manufacturing and production operations, and exposing the wearer to the possibility of disease. Wire will invariably fracture after repeated flexure and will penetrate the surface of any known composite yarn.
The present inventor has discovered that the invention taught herein provides a method of containing wire and other materials such as fiberglass when these materials are used as the yarn core. To date there has been no serious attempt by the Food and Drug Administration (FDA) or the U.S. Department of Agriculture (USDA) to eliminate the use of such materials as a yarn core, but the issue is volatile and will eventually need to be resolved. The resolution may not be one which industry finds acceptable or even practical.
Wire and fiberglass are known to provide additional cut resistance to composite yarns by microscopically altering the edge of the cutting surface. This is due to exceptional high density and abrasiveness which dulls the edge of any cutting instrument or device that contacts the material. Wire and fiberglass also add strength to a yarn. The materials are preferred because of the many benefits they add to a composite relative to the cost. However, these same materials are controversial because they cannot be allowed to escape from the composite yarn into the work place for environmental and/or health reasons. The present invention provides a composite yarn and fabric which may selectively incorporate wire and/or fiberglass and/or other necessary but potentially harmful materials into the basic yarn core, but which offers protection to the worker from exposure to the materials, which materials may fragment or splinter and threaten the health of the worker and also damage the end product.
The present invention provides a novel method of forming a containment barrier around a single component or multi-component core of such controversial and potentially contaminating materials, and substantially decreases the risk of these contaminates being released. The foundation of the present invention is a composite yarn which uses melt-fusible thermoplastics to encapsulate and thereby isolate one or more core materials which may present a threat of contamination to workers or the environment. This novel yarn is basically comprised of one or more core materials which are covered in thermoplastics and additional layers of materials which form one or more outer covers. The combination is then heat set to form a flexible fiber barrier which surrounds and entraps the unsafe core.
The barrier which contains the selected core is created by melt fusing a thermoplastic material with other differing fiber products in such a way that these undesirable materials are trapped between a shroud of fused fibers and a fiber core. In other embodiments, materials which are longitudinally positioned to form the core are encapsulated in a continuous fibrous sheath with no adhesion between the sheath and an inner core yarn.
It is preferred to trap wire in a fused-fiber layer having a smooth outer surface which is unlikely to bond with subsequent outer cover layers. Because wire itself has a smooth surface unlikely to bond with thermoplastic, it is important that the core bond to the thermoplastic and isolate the wire therebetween. The combination becomes a highly effective containment vehicle that retains a high level of flexibility. While the end product such as a glove may become slightly more rigid after heat treating to retain shape, the composite yarn is highly flexible and can therefore be easily knitted, woven, braided, or otherwise formed into a glove or other product. There are many different materials and processing methods available to form the composite yarn, depending on the end use desired. Conventional covering or wire-wrapping equipment is most suitable to manufacture the composite yarn. Other equipment may be used as needed to preprocess materials which can later be wrapped or used as wraps. Examples are commingle machines, twisting equipment, and extruding machines.
The core of the composite yarn is selected from a group of fibers or types of other materials which may be spun, continuous, multifilament, or monofilament, The core is selectively comprised of a single strand or multiple strands of single fiber type or a mixture of fiber types. The core structure is virtually unlimited and may include fiberglass, wire strands, thermo-plastics, and/or other such controversial materials or combinations of such materials. The core structure may be of a plurality of such fibers combined by blend spinning, twisting, extrusion or any other method deemed appropriate to accomplish the desired core and end product.
Several previously unknown benefits of yarns manufactured in accordance with these methods have been discovered. It has been found that abrasives such as wire or fiberglass perform their function better when locked firmly in place. The function of abrasives in cut resistant yarns has been explained as dulling the cutting edge and thereby increasing the performance of the other high strength fibers. When wire is used, it tends to move away from the cutting edge exposing more fiber to the threat. When wire is fused in place as with the present invention, it engages the edge more directly and is more abrasive. It effectively shields subsequent layers until the full abrasive effect is used. This is also true with fiberglass. Fiberglass is not effective once it is fragmented and this occurs quickly upon contact with the cutting edge and during normal flexure. By bonding the glass with the methods described, it is less easily shattered. The maximum abrasive ability is obtained by presenting the glass as a unified and unmoving abrasive surface that is not easily shattered. By making these abrasives more effective, it is now possible to attain equal cut protection with a lower abrasive content or to increase protection with equal contents.
When the cutting threat is from a chopping blow as opposed to a slashing movement, the present invention also exhibits unique abilities. The fused fibers of the invention are pulled in the direction of the cutting edge thus increasing the concentration of protective fiber and abrasives in the threat area. This increases the level of protection to this type of threat.
It has also been found that this method of manufacturing creates a yarn with improved abilities to absorb impacts and vibration of all types. This is due to the resilient properties present in the compounds used for fusing the composite together. This characteristic is useful to dampen vibration and provide a measure of protection from blunt trauma.
The core containment barrier has been found more useful in containing wire than originally believed. It was believed that longitundinally positioned strands of wire should not exceed .002 inches diameter due to an increased likelihood of puncturing the containment barrier. Success was found with longitudinal wire strands of .006 inch diameter without increasing the overall diameter to the finished yarn. This allows the use of heavier wire strands with minimal risk of barrier puncture.
Finally, it has been observed that embodiments having cores formed largely of melt fusible thermoplastics become hollow after heat treatment. These embodiments are very unique and exhibit improved ductility. This is important in apparel applications where wearer comfort is important.
In some embodiments, rather than bond the core to the thermoplastic, it is desirable that the selected core is next covered with a layer of material which creates an inner core containment barrier separating the core from the surrounding melt-fusible thermoplastics. This is necessary to prevent the core structure from bonding with the thermoplastics and thereby restricting flexibility. Core materials that are particularly brittle will deteriorate quickly if not allowed to move freely within such a shroud. This inner core containment barrier layer may be of any material which has a higher melt point than the thermoplastics which surround it.
Using the heat-set method rather than liquid internal coating, a preferred embodiment includes a basic core, and around the circumference of the basic core, the first layer of one or more strands of wire may be wrapped to provide a second component to the basic core. The wire may be wrapped in one direction with one or more strands applied parallel to each other, or the wire may be twisted or combined in any other known way. The wire may also be wrapped in opposing directions relative to each other, with one strand being clockwise, and the other counterclockwise. The preferred wire is an annealed stainless steel 304 with a range of .008'' diameter or smaller. The most preferred is .0045'' for a single wrap, or .003'' for a double wrap. Finer strands may be used when there is a combined plurality of wire strands. In such embodiments, using wire of .002'' diameter or more, wrapping is preferred. The wire wrapped about the basic core may be wrapped at a pitch of one to 100 turns per inch as the embodiment requires. It has been observed that the helical shape which is thus formed directs the wire's angle more to the center of the composite yarn structure. This becomes important when a wire strand fractures. Longitudinally positioned wire strands tend to project a rigid point when broken. This rigid point is then so oriented as to puncture the surface when the yarn is flexed and is difficult to contain.
Following application of the wire component and/or the containment barrier, an additional layer to be added to the cornposite is selected from the group of melt-fusible thermoplastics. These may be polypropylene; low, high, or ultra-high-density polyethylene; low-melt nylon polyamid; or polyamid blends; or low-melt polyesters. A number of higher melt temperature thermoplastics exist which have not been tested, but are believed to be applicable for higher temperature applications and embodiments. This layer may be applied in several different ways, including wrapping, twisting, spinning about the core and the containment barrier; may be longitudinally positioned with the core, extruded over the core, or blended with the core, commingled with the core, or any combination of these methods. The thermoplastics also may be applied to the wire strands prior to wrapping the strands around the basic core. The selected method of combining the thermoplastics with the wire is dependent upon the number and size of the wire strands being utilized. The wire strands may be wrapped, twisted, paralleled, paralleled and wrapped with more thermoplastic, paralleled and wrapped with very fine denier non-thermoplastic, or the wire may be coated by means of any of the more conventional coating methods.
Selected thermoplastics for this layer may be monofilament, multifilament, spun or blended with other materials. The percentage of thermoplastic content in this layer is limited only to that which is necessary to properly contain and stabilize the underlying materials. When combining with the wire prior to wrapping the wire around the basic core, two benefits are attained. First, prior combining allows a step to be eliminated in processing by not requiring a separate wrapping of thermoplastic. Secondly, the thermoplastic is concentrated only in the area which surround the wire, leaving some unfused areas to increase the flexibility of the composite. Some of the more effective methods will be detailed below.
The next layer is the primary core containment barrier and is selected from a broad group of synthetic or organic materials including but not limited to: polyester, nylon, aramid, high density polyethylene, ultra high molecular weight extended chain polyethylene, such as Allied's Spectra™, cotton, wool, polycotton, rayon, Hoechst Celanese's PBI™, Dupont's Teflon™, and blends. The exceptions are those materials which are the same as those to be contained, and materials having melt points which are lower than the selected thermoplastic. This layer serves several functions:

1) It forms the layer of fiber which is fused with the underlying adhesive layer to form a shroud. In certain embodiments wrapped wire is the material to be contained and this layer is utilized to fuse with the basic core material around which the wire is wrapped. This results in a sandwich effect that thoroughly traps the wire in a flexible capsule or fused fibrous material which is almost impenetrable.
2) In embodiments using wrapped wire, this shroud functions to prevent the wire from moving as the composite is heated. The selected fiber must therefore be of reasonably high tenacity and not generally susceptible to loss of strength at the fusion temperature of the underlying thermoplastic.
3) This layer adds cut resistance to the finished composite yarn.
4) This layer serves as a shroud which has sufficient thickness to absorb the underlying melt-fusible polymer and prevent the polymer from passing to the outer wraps. This is of particular importance when subsequent outer covers must be able to function independently of the core and barrier yarns. Independent movement is sometimes necessary primarily for flexibility, but also allows the performance characteristics of the yarn not to be impeded by entrapment. It has been observed that yarns are more cut and/or abrasion resistant when the yarns are allowed to move freely with the cutting or abrading surface. This is simply illustrated by observing the relative ease with which a yarn may be cut under tension, versus one that is cut under less tension.

In addition to the above functions, when used in the wrapped wire embodiments, it is preferred that this third layer be wrapped at the number of turns per inch which provides an angle as close to 90 degrees relative to the wire as feasible. Near perpendicular angles are optimal to allow the finished composite yarn to perform. Present embodiments have attained 70 degree angle at eight (8) turns per inch using 840 denier nylon. In other embodiments it is necessary to apply a lighter denier at a very high range of turns per inch. This is particularly true where multiple ends of wire are wrapped in opposing directions. The turns per inch must be a combination of optimal angles, total encapsulation, density of the layer and the fiber's ability to prevent movement of the wire during the heat cycle. It should be noted that the type 304 alloy of stainless has a coefficient of thermal expansion equal to 10.1 * 10-₆ per degree rise in temperature Fahrenheit. If the composite is processed at 295 degrees Fahrenheit then a one-inch section would normally expand to 1.00226846''. While this amount of movement may appear small, it does have the ability to deform the fabric if not controlled. Testing has shown that wire can push through the thermoplastic layer as the wire expands during the heat cycle, and this movement prevents a proper bond from forming because the thermoplastics tend to cool more quickly than wire. This layer ideally should be wrapped with a comparable range of turns per inch as the underlying core using a yarn of sufficient weight or diameter to provide complete coverage and density. However, yarns from 20 to 4800 denier may be used and may be applied from three to 200 turns per inch as the embodiment requires. This shroud layer may be one or more wraps in similar or opposing directions relative to one another. As with the basic core, this layer can be made up of a multiplicity of yarns, depending on the desired end effect or product.
In the preferred embodiments described below, it will be obvious that the simpler methods and yarn combinations achieve the best results.
A final, or outer layer may be added. This outer layer is of particular importance when the underlying layer is not capable of absorbing the molten thermoplastic and preventing it from rising to the surface of the finish product (known as "wet out"). The fiber content of this outer layer may be selected from the same group as the wire-containment wrap. There may be one or more of these outer wrap layers and each may be similar or dissimilar. The selected material wrap may be of a single strand, multiple strands of a single yarn or a multiplicity of differing yarn fibers or types. This outer layer may also be spun over the underlying layers as with friction spinning equipment.
With use of such overlying multiple layers it is preferred, but not required, that each of the layers be wrapped in opposing directions. This method of wrapping in opposing directions is known as counterbalancing and has the effect of making the yarn balanced, straight, and with separate covering layers that tend to lock together and do not easily fray.
The combined selection of yarn fibers and types is based primarily on the end use of the yarn, the fabric or the product. Some of the more common materials are nylon, polyester, aramid, extended chain polyethylene, rayon, cotton, or wool. However, the fibers/types may be selected from any of the synthetic or natural materials group. Any one of the layers or wraps may serve any of the functions of enhanced cut resistance, abrasion resistance, improved comfort to the wearer, increased thermal performance, enhanced texture for handling special materials, improved knitability, or other such characteristics.
The finished novel composite yarn is applicable to knitting, weaving, braiding, twisting, or otherwise forming into a desired fabric or product. Once the end product is provided, the final step of thermoplastic fusion generally takes place. Treatment temperatures and exposure times will vary according to the characteristics of the thermoplastic,, density of the composite and thickness of the article manufactured. With gloves, for example, a typical heat treating method would make use of a glove dotting machine which is designed for precise temperature and exposure time control. Yarns may also be heat treated on the package in a dry or wet yarn conditioning oven.

DESCRIPTIONS OF THE DRAWINGS

Figures 1A and 1B, 2A, 2B and 2C, 3, 4, and 6 are schematic representations of various embodiments of the composite yarn; and
Figure 7 is a perspective view of a glove made from the composite yarn.

DESCRIPTION OF PREFERRED EMBODIMENTS

These definitions will be helpful in identifying the various designations and functions of the described layers.

(1) Basic Core: May be one or more longitudinal materials including all thermoplastic fibers, and carbon fibers or other possible contaminate groups. Basic core may have these selected materials spun, wrapped, twisted or coated over one or more longitudinal members.
(2) Inner Core Containment Barrier: This is an optional layer for use in those embodiments that require separation of the core andadhesive layers. It may be spun or wrapped over the basic core. Selected materials only exclude those contaminates of the basic core or materials with melt temperatures equal to or lower than the thermoplastics of the heat processed embodiments.
(3) Adhesive layer: This layer may be used as the only source of adhesives, in conjunction with adhesives in the basic core, or not used at all when sufficient adhesion is available from materials in the basic core. The layer may be wrapped, spun, coated, twisted or positioned longitudinally to the basic core or containment barrier layers.
(4) Primary Core Containment Barrier: From the same group of materials selected for the inner core containment barrier; may be wrapped or spun over the inner layers and be singular or a plurality of yarns combined in any way.
(5) Outer Layers: From the same group of containment barrier fibers; this layer or layers is optional to enhance performance as needed.

Looking first at Figure 1A, a first embodiment is detailed as having a basic core 20 formed of 840 denier industrial grade nylon. A single wrap 25 of .0045'' diameter annealed stainless wire is applied over core 20, applied at approximately eight turns per inch of core length. Wrapped about this single wire wrap 25 is a low-melt-temperature thermoplastic adhesive layer 30 of a type such as .006'' Shakespeare monofilament NX 1012 terpolyamide forming a wire/thermoplastic layer 32. The thermoplastic barrier layer 30 is applied over wire 25 at approximately 100 turns per inch of wire core length. A prirnary core containment barrier, 35 is applied in the opposite direction (relative to the wire/thermoplastic layer 32) and is preferably formed of 840 denier industrial grade nylon; again wrapped at approximately eight turns per inch of core or yarn length. A final outer layer 40 is comprised of one strand, wrapped in a direction opposite to the underlying layer 35, or approximately eight wraps per inch of core or yarn, formed of 840 denier industrial grade nylon.
While this embodiment in Figure 1A is one of the basic approaches, it combines the thermoplastic fiber with the wire wrap prior to wrapping the wire around the core. Thus the adhesive action of the thermoplastic is concentrated in the critical areas. By wrapping the wire with 840 denier nylon, the wire and nylon intersect at an optimal angle to contain the thermal expansion of the wire while still maintaining total coverage of the wire. Test results of this embodiment indicate that the composite yarn is equally cut-resistant to any other known wire yarn products, and exhibits no detrimental rigidity resulting from the unique encapsulation of the wire.
Using the same basic structure of layers shown in Figure 1A, another embodiment shown in Figure 1B features a core material 20' of 1200 denier extended chain polyethylene wrapped with a strand 25' of .0045'' diameter annealed stainless steel at approximately five turns per inch. The .0045'' diameter steel wire 25' is itself wrapped with conventional multifilament or monofilament polyethylene 30' of approximately 200 denier before the wire is wrapped around the core 20'. A subsequent wrap 35' is, in this embodiment, formed of 650 denier extended chain polyethylene at a range of five or six wraps or turns per inch to completely cover the wire layer. The final outer wrapping 40' is formed of 840 denier industrial grade nylon wrapped at approximately eight turns per inch of core or yarn.
It should be noted that this second basic embodiment described with reference to the layered structure of Fiber 1B utilizes an extended chain polyethylene having a melt point of approximately 297 degrees Fahrenheit to form layer 35', to wrap or cover the wire which has been previously wrapped with a conventional polyethylene 30' having a melt point of approximately 200 degrees Fahrenheit, to ensure formation of an adhesive bond between the encapsulating primary core containment barrier 35 and the core. Such a structure is preferred because the conventional polyethylene helps compensate for the poor adhesive performance of extended chain polyethylene. This structure also offers an exceptionally high level of cut resistance and an equally good ability to encapsulate the wire because of extended chain polyethylene's unsurpassed strength and cut resistance. Nylon is used as the outer wrap 40' because of its dissimilarity from the core. If the heat application is not precisely controlled the extended chain polyethylene material can reach the softening point and bond with the outer covers, thus increasing the likelihood of rigidity in the end product.
Looking next at Figure 2, and cross-sectional views 2A, 2B, a third embodiment has a core 50 formed of a single strand of 900 denier fiberglass. Positioned longitudinally of this core 50 is an adhesive layer 52 of three spaced apart strands of .006'' Shakespeare NX 1012, strands 52a, 52b, and 52c, having a melt point of 275 degrees Fahrenheit. A single encapsulations shroud or core containment barrier 54 is formed of 840 denier high tenacity nylon wrapped over the underlying materials at approximately eight turns per inch of core or yarn. A subsequent outer cover 56 is formed of the same 840 denier nylon wrapped in the opposite direction (relative to 54) at approximately eight turns per inch. In this example the terpolyamide (melt fusible nylon) does not completely contain the core prior to application of heat. However, during the heat cycle the composite has a sufficient quantity of this melt fusible material to flow around the entire circumference of the core (Figure 2C). Because the 840 denier nylon encapsulation shroud 54 is a polyamide, an excellent bond is formed with the melt fusible terolyamide 52a,b,c. Residual polymer will adhere to the fiberglass core. The outer wrap 56 is not fused to the encapsulation shroud 54 because there is sufficient layer of the inner wrap to absorb the melt fusible material.
Figure 3 illustrates a fourth embodiment which utilizes fourteen strands of 35 micron stainless steel type 304 to form a longitudinally oriented basic core 70. The core 70 is wrapped with 650 denier extended chain polyethylene at five turns per inch to form an inner core containment barrier 72. Then multiple strands of.005'' low density polyethylene monofilament are added to longitudinally surround the wrapped core, parallel to the fourteen strands of steel which form core 70, thus forming adhesive layer 74. A final outer layer of 200 denier TFE flurocarbon (such as that made by Dupont Corporation and sold under the trademark Teflon™) is wrapped in the opposite direction (relative to wrap 72) at approximately twelve turns per inch, to form the outer cover or primary core containment barrier 76. In this example, unusually fine strands of wire are used to create a highly flexible basic core 70 which has a resulting denier equivalent to 1000 denier; yet each of the individual strands is unable to puncture the relatively fine barrier layer 72. The containment barrier of extended chain polyethylene which forms the inner core containment barrier 72 is preferably Allied Signal's product sold under the trademark Spectra 1000™.
This figure 3 embodiment is somewhat unique when compared to the other embodiments taught herein, in that the final wrap 76 is in direct contact with the adhesive layer 74 and is therefore fused to the other materials. It has been found that due to Teflon's™ lubricity it must be fused in order to prevent the Teflon™ layer from moving and exposing the materials beneath. Furthermore, Teflon™ does not need to function independently in order to adequately perform in this embodiment. The unusually heavy layer prevents the thermoplastic 74 from flowing to the surface. This embodiment is particularly suited to use in production of a cut resistant surgeon's glove which would be worn so as to underlie the conventional sterile latex glove used in most surgical facilities.
Figure 4 illustrates a fifth embodiment wherein a core 90 is formed of 1000 denier Kevlar 29™ (aramid) made by Dupont Corporation. Positioned longitudinally to this core 90, are contained by a layer 94 formed of Dupont Corporation's type 68 polyester of approximately 1000 denier which has been modified to incorporate two parallel strands 95a and 05b and 160 denier polyethylene. This layer 94 is wrapped at approximately five turns per inch in the opposite direction to the wrap of the outer wire layer 92b. A final outer covering 96 is formed of the same polyester and is wrapped at approximately five turns per inch in a direction opposite that of the contained layer 94. This composite yarn is suitable for production of gloves which are knitted and then heat treated for approximately five minutes at 340 degrees Fahrenheit in a conventional glove dotting machine.
In this embodiment of Figure 4, the adhesive layers 91,a,b,c are beneath the wire layers. Additional thermoplastic is commingled with the primary core containment barrier 94 for ease of processing. Because two strands of wire 92a and 92b are used in opposing directions, the primary core containment barrier 94 is applied outside to the outer wire wrap 92b. Since the first, or inner wire strand is wrapped with the same number of turns and in the same direction as the barrier 94, it would normally push through the commonly oriented filaments of polyester during the heat cycle. By wrapping opposite the outer wire strand, and thereby controlling its expansion, the inner wire strand is thus also controlled. Polyester is useful as an encapsulating shroud and as a final wrap due to its shrinkage of approximately fourteen percent of the heat-set temperature of 340 degrees Fahrenheit. Shrinkage causes the polyester to contract against the expanding wire and form more closely with the core material, establishing a strong adhesive bond.
The embodiment in Figure 6 demonstrates there are a variety of yarn constructions that fall within the teachings of this disclosure and claims, and can be used to create the same or similar products. This embodiment is comprised of a core 110 formed of approximately fourteen strands of 35 micron type 304 stainless wire such as that manufactured by Beckert Company. Wrapped about this core 110 is a layer 115 formed by combining a wrapping 115a of 200 denier industrial grade multifilament nylon, wrapped at approximately thirty turns per inch of core, with a paralleled strand 115b of .006'' strand of melt fusible terpolyamide monofilament. The preferred terpolyamide monofilament is Shakespeare NX 1012 which has a melt point of 275 degrees Fahrenheit. Positioned parallel to the core 110 and overlying 115 is a single strand 114 of 1200 denier TFE flurocarbon such as Teflon™. The Teflon™ is carefully fed through a device which first flares the width of the multifilament, then tapers around the core so as to surround the inner surface of the core 110 and 115 with Teflon™ filaments. A final outer wrap 116 of 20 denier nylon is wrapped at a range of five to eight turns per inch in the opposite direction relative to the inner layer 115. This final wrap 116 holds the Teflon™ in place until the composite yarn is heat treated.
Figure 8 illustrates a yarn construction wherein the core 200 is formed of an industrial grade polyester (500 denier) 202 combined with a single strand of .003'', type 304, stainless steel wire 205. The adhcsive layer 210 is helically wrapped about the basic core 200 at approximately seven turns per inch, preferably formed of 350 denier, 70 filament, low density polyethylene. Over this adhesive layer is a primary core containment barrier 215 formed of 500 denier industrial grade polyester which is helically wrapped at approximately nine turns per inch. A final outer layer 220 of 1000 denier industrial grade polyester is wrapped in the opposite direction at a pitch of approximately eight turns per inch. The finished yarn is then heat set for approximately two and one-half to two and three-quarter hours, at 280 degrees F. in a steam conditioning unit. The yarn of this embodiment is highly suited for use In construction of industrial gloves and other cut-resistant fabrics.
Figure 9 illustrates a basic core 300 of 150 denier textile grade polyester 302 and 100 denier, 70 filament low-density polyethylene 305. Wrapped about this basic core is a single strand 310 of .002'', type 304, stainless steel wire which is wrapped at a pitch of twenty-four turns per inch. The primary core containment barrier 315 (the final layer) is 300 denier textile grade polyester wrapped in a direction opposite that of the wire, at a pitch of approximately ten turns per inch. The finished yarn is then heat set for one and three-quarter hours at 280 degrees in a steam conditioning unit. This embodiment is best suited for finer cut-resistant fabrics and most particularly for cut-resistant surgical gloves.
Figure 7 illustrates a cut-resistant glove made from any one of the embodiments of the composite yarn described above. It demonstrates improved cut resistance, flexibility and comfort. Other end products are anticipated to be made from the novel yarn described herein, other embodiments of the yarn are anticipated, and all are believed to be within the scope of the claims below.

Claims

Claim 1. A composite yarn structure, the yarn being in strand form and structured to include an isolated core material which may have a hazardous characteristic thereto; which composite yarn is of the type utilized for knitting or weaving fabrics for apparel products, for production of industrial fabrics for braiding, for production of cordage, or for production of non-woven goods; said composite yarn structure including: A) a basic core member formed of one or more selected materials including wire, fiberglass, thermoplastics, filaments, or spun fibers, or combinations thereof, with said basic core member being longitudinally oriented relative to the finished strand of said yarn; B) at least one core containment barrier being formed of a selected material having a first melt temperature; C) an adhesive component associated with said basic core member and said core containment barrier; said adhesive component including one or more selected thermoplastic materials having a second melt temperature which is lower than said first melt temperature of said core containment barrier; D) a fused fiber layer formed by the heat fusion of said adhesive layer and said core containment layer; whereby said composite yarn demonstrates fexibility sufficient to enable the conventional processes of manufacturing the desired end product.
Claim 2. A composite yarn structure according to claim 1 wherein said basic core member is comprised of at least one strand of aramid and at least one strand of multifilament thermoplastic positioned in parallel relationship to said strand of aramid thermoplastic strands being of a prescribed denier; and said thermoplastic having a melt temperature lower than that of said aramid component.
Claim 3. A composite yarn structure according to claim 1 wherein said basic core member is comprised of a plurality of strands of wire material of a prescribed gauge.
Claim 4. A composite yarn structure according to Claim 1 wherein said adhesive component is formed of a thermoplastic material selected from the group including polypropylene; ultra-low, low, high, or ultra-high density polyethylene; low melt nylon polyamide; polyamide blends, and low-mett polyesters.
Claim 5. A composite yarn structure according to Claim 1 wherein said core containment barrier is formed of a material selected from the group including: polyester, nylon, aramid, high-density polyethylene, ultra-high-molecular-weight extended chain polyethylene, cotton, wool, polycotton blends, rayon, or TFE flurocarbon, PBO, PBZT, PTI.
Claim 6. A composite yarn structure, the yarn being in strand form and structured to include an isolated core material which may have a hazardous characteristic thereto; which composite yarn is of the type utilized for knitting, for braiding, for weaving fabrics for apparel products, for production of industrial fabrics, for production of cordage, ot production of non-woven goods; said composite yarn structure including;
A) A basic core member formed of a selected material or combination of materials including wire, fiberglass, thermoplastics, filaments, or spun fibers; said core being longitudinally oriented relative to the finished strand;

B) an adhesive component positioned intermediately of said basic core member and subsequent overlying layers; said adhesive component encapsulating said basic core member and isolating said basic core member from subsequent overlying layers; said adhesive layer including one or more selected thermoplastic materials which, when heat treated, forms a fused fiber layer between said basic core and any additional outer layers, demonstrates flexibility sufficient to enable the processes of knitting and weaving;

C) at least one outer layer overlying said adhesive layers, said outer layer being formed of a selected material having a melt temperature higher than that of said thermoplastic material used to form said adhesive layer;

D) at least one cover layer formed of a selected material and being applied around the underlying layers to a prescribed thickness;
whereby said composite yarn structure enables use of core materials traditionally considered of a hazardous nature by isolating said core material from subsequent outer layers, while retaining the flexibility and cut-resistance necessary for the knitting or weaving of fabrics, protective apparel, and the like.
Claim 7. A composite yarn structure according to Claim 6 and further including said basic core member having:
A) a first component comprised of a selected filamentary material being longitudinally oriented relative to the finished composite yarn strand; and

B) a second component comprised of at least one strand of wire material of a prescribed gauge; said strand of wire material being helically wrapped around said longitudinally first component a prescribed number of turns per linear inch of said finished composite yarn strand.
Claim 8: A composite yarn structure according to Claim 6 and further including: said basic core member having:
A) A first component comprised of a selected filamentary material being longitudinally oriented relative to the finished composite yarn strand; and

B) at least one strand of wire material of a prescribed gauge being parallel to said basic core member.
Claim 9: A composite yarn structure according to Claim 7 wherein said filamentary material which comprises said first component is fiberglass.
Claim 10: A composite yarn structure according to Claim 7 wherein said filamentary material which comprises said first component is asbestos.
Claim 11: A composite yarn structure according to Claim 7 wherein said filamentary material which comprises aid first component is a carbon fiber.
Claim 12: A composite yarn structure according to Claim 7 wherein said first component is comprised of at least one strand of Aramid and at least one strand of multifilament thermoplastic having a melt temperature lower than that of said aramid, and positioned in parallel relationship to said aramid; each of said aramid and said polyethylene strands being of a prescribed denier.
Claim 13: A composite yarn structure according to Claim 7 wherein said first component is comprised of a plurality of strands of steel wire material of a prescribed gauge.
Claim 14: A composite yarn structure according to Claim 6 wherein said adhesive component is formed of a thermoplastic material selected from the group including polypropylene; ultra-low, low, high, or ultra-high density polyethylene; low-melt nylon polyamide; polyamide blends; and low-melt polyesters, or blends.
Claim 15: A composite yarn structure according to Claim 14 wherein said adhesive component is formed of a prescribed number of strands of .006'' terpolyamid.
Claim 16: A composite yarn structure according to Claim 6 wherein said outer cover layer is formed of a material selected from the group including: polyester, nylon, aramid, high density polyethylene, cotton, wool, polycotton blends, rayon, PBO, FBZT, PBI, TFE flurocarbon, ultra-high molecular-weight extended chain polyethylene.