Fire-resistant, cut-resistant, and elastic recovery yarns and fabrics and processes for making same

Abstract

A ply yarn, and fabrics and articles comprising the ply yarn, the ply yarn comprising: (a) at least one first yarn comprising at least 50 weight percent heat resistant polymeric fibers, wherein at least 30 weight percent of the polymeric fibers present in said yarn are cut resistant heat resistant polymeric fibers having a cut resistance of 500 grams force or greater according to ASTM F2992-15; (b) at least one second yarn having a sheath / core structure with a sheath of halogenated self-extinguishing staple fibers and a core comprising at least one continuous elastomeric filament; (b) 60 to 95 weight percent of the halogenated self-extinguishing fibers are in contact with elastomeric filaments, and the halogenated self-extinguishing fibers are free or substantially free of inorganic fibers, and fabrics and articles comprising the ply yarn.

Description

[Technical field]

[0001] 1. FIELD OF THEINVENTION The present invention relates to yarns and fabrics suitable for use in articles of protective clothing that are fire resistant and conformable, as well as cut resistant. [Background technology]

[0002] 2. Description of Related Art Cut-resistant and elastic recovery ply yarns and fabrics, processes for making the same, and their use in articles of protective clothing are disclosed in U.S. Patent No. 6,952,915.

[0003] Yarns containing modacrylic, p-aramid and m-aramid fibers that are useful for making fabrics with arc and flame protective properties are disclosed, for example, in U.S. Patent Nos. 7,065,950 and 7,348,059. These yarns may further include, as optional components, 2-15 weight percent of an abrasion resistant fiber such as nylon and / or 1-5 weight percent of an antistatic component.

[0004] Yarns and fabrics having a combination of fire resistance and elastic recovery are described, for example, in U.S. Patent Nos. 5,069,957, 5,527,597, and 5,694,981. These existing solutions utilize yarns made by covering an elastic core yarn with a substantially protective outer covering of fiber made from fire resistant fibers. In other words, these references describe protecting an elastic core by structurally shielding it from flames using another fiber in the same yarn.

[0005] As used herein, the terms "structurally insulating" and "structurally insulating" mean that the covering fibers readily char when exposed to flame and remain in place in the yarn covering any elastic filaments in the core, thus providing a structural barrier between the flame and the elastic core. As taught in these patents, the yarns are provided with a substantially protective fibrous outer covering made of fire resistant fibers that physically protect the elastic core yarn from degradation or melting when exposed to extreme temperatures and fire.

[0006] Unfortunately, in many cases, the fibers that provide adequate structural shielding of the outer fabric also tend to be stiffer fibers, so fabrics made with such yarns may not be as comfortable as desired. This ultimately results in protective clothing that may be less comfortable than desired, and it is well known that if it is not comfortable enough, workers tend not to wear the protective clothing, putting themselves at risk.

[0007] Additionally, any solution to protect the elastic core must meet current protective clothing standards. Specifically, the new NFPA 2112-2018 "Standard on Flame-Resistant Clothing for Protection of Industrial Personnel Against Short-Duration Thermal Exposures from Fire" provides specifications for minimum design, performance, testing, and certification requirements, as well as test methods for flame-resistant garments, shrouds, hoods, balaclavas, and gloves for use in areas where there is a risk of short-term thermal exposure from fire. The standard requires that fabrics used in the garments have an afterflame time of 2 seconds or less. Afterflame time is the time, in seconds, that a test specimen continues to burn after the burner is removed from the flame, down to 0.2 seconds.

[0008] This standard has an even more stringent requirement for flame-resistant gloves, in that the material consumed during the flame resistance test must not exceed 5.0 percent of the original weight of the specimen. In other words, after applying a flame for the specified 12 seconds to the specimen according to the standard's procedure, the weight loss of the fabric must be less than 5.0 percent. Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, what is needed is a yarn and / or fabric that has a combination of fire resistance and elastic recovery along with cut resistance, specifically incorporating elastic core yarns, meeting the NFPA 2112-2018 standard, and further utilizing fibers with a textile feel to potentially provide more comfortable protective apparel. [Means for solving the problem]

[0010] The present invention relates to a ply yarn suitable for use in flame resistant, cut resistant fabrics, and fabrics and articles containing same, the ply yarn comprising: (a) at least one first yarn comprising at least 50 weight percent heat resistant polymeric fibers, wherein at least 30 weight percent of the polymeric fibers present in the at least one first yarn are cut resistant heat resistant polymeric fibers having a cut resistance of 500 grams force or greater according to ASTM F2992-15; (b) at least one second yarn having a sheath / core structure with a sheath of halogenated self-extinguishing staple fibers and a core comprising at least one continuous elastomeric filament; In this case, 60 to 95 weight percent of the at least one second yarn is a halogenated self-extinguishing fiber, the halogenated self-extinguishing fiber is in contact with the at least one continuous elastomeric filament, and the second yarn is free or substantially free of inorganic fibers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention relates to yarns and fabrics suitable for use in protective clothing articles that are both fire resistant and conformable, while also providing cut protection. This unique combination is created by combining elastic materials, self-extinguishing fibers, and strong, heat resistant polymeric fibers to provide high fire resistance in the yarn or fabric while limiting fabric consumption during combustion.

[0012] In particular, the present invention relates to a ply yarn suitable for use in flame resistant, cut resistant fabrics, the ply yarn comprising: (a) at least one first yarn comprising at least 50 weight percent heat resistant polymeric fibers, wherein at least 30 weight percent of the polymeric fibers present in the at least one first yarn are cut resistant heat resistant polymeric fibers having a cut resistance of 500 grams force or greater according to ASTM F2992-15; (b) at least one second yarn having a sheath / core structure with a sheath of halogenated self-extinguishing staple fibers and a core comprising at least one continuous elastomeric filament; In this case, 60 to 95 weight percent of the at least one second yarn is a halogenated self-extinguishing fiber, the halogenated self-extinguishing fiber is in contact with the at least one continuous elastomeric filament, and the second yarn is free or substantially free of inorganic fibers.

[0013] The yarn can provide a fabric with a maximum afterflame time of 2 seconds or less and a weight loss of 5 weight percent or less when tested in accordance with NFPA-2112-2018.

[0014] "Flame resistant cut resistant fabric" means a knitted or woven fabric that is both "flame resistant" and "cut resistant." The term "flame resistant" in reference to a fabric means that the fabric has a char length of 4 inches (100 mm) or less when tested according to ASTM 6143-15. "Cut resistant fabric" means that the fabric has at least a minimum level of cut resistance, generally having a cut resistance of at least 200 grams force according to ASTM F2992-15. In some preferred embodiments, the fibers and yarns described herein can provide a flame resistant cut resistant fabric having a cut resistance of at least 500 grams force according to ASTM F2992-15. However, it is understood that in some other embodiments, so long as the flame performance requirements described herein are met to be considered a "flame resistant" fabric, and the fabric retains a minimum cut resistance of at least 200 grams force per ASTM F2992-15, other fibers or yarns may be incorporated into the fabric that do not necessarily provide cut resistance, but may provide other desirable qualities to the fabric.

[0015] Flame resistant fabrics provide thermal protection from thermal events, and cut resistant fabrics provide mechanical protection from objects such as knives and sharp blades. In addition, it is often important or desirable that any article, such as a protective glove, made from such fabrics be comfortable and have good fit and dexterity. "Good fit and dexterity" means, for example, that the glove conforms well to the shape of the wearer's hand, allowing the wearer to grasp and manipulate small objects while wearing the glove. Flame resistant cut resistant fabrics that can be provided by the yarns described herein provide articles that are both highly flame and cut resistant, and also soft, flexible, and form-fitting. Protective garments made from such fabrics are very comfortable and effective against multiple threats.

[0016] The flame resistant, cut resistant fabric is made from at least a first yarn providing a heat resistant polymeric fiber and at least a second yarn providing at least one continuous elastomeric filament covered with a halogenated self-extinguishing fiber in contact with at least one continuous elastomeric filament. The at least first yarn and the at least second yarn are then used to make a fabric.

[0017] At least a first yarn and at least a second yarn are twisted together to form a ply yarn. In some embodiments, the ply yarn is comprised of only one first yarn and only one second yarn. In other embodiments, the ply yarn is comprised of only one first yarn and multiple second yarns, and in other embodiments, the ply yarn is comprised of multiple first yarns and only one second yarn. Similarly, in some embodiments, the ply yarn is comprised of multiple first yarns and multiple second yarns. Finally, in some embodiments, the ply yarn includes at least one first yarn and at least one second yarn, and other yarns made from any number of fibers can be included in the ply yarn, so long as the final fabric meets the performance criteria discussed herein.

[0018] The at least one first yarn comprises at least 50 weight percent of heat resistant polymeric fibers, based on the total weight of the first yarn, and at least 30 weight percent of the polymeric fibers present in the at least one first yarn are cut resistant heat resistant polymeric fibers having a cut resistance of 500 grams force or greater according to F2992-15, and the at least one first yarn further comprises a sheath / core structure with a sheath comprising the cut resistant heat resistant polymeric fibers and a core comprising inorganic fibers. The reason for the sheath / core structure is that the sheath staple fibers provide coverage and shield the inorganic filaments in the core from direct abrasive contact with the skin, improving the comfort of the textile comprising the sheath / core yarn.

[0019] "Heat resistant polymer fiber" means a fiber made from a synthetic organic polymer that retains 90 percent of its original fiber weight when heated to 500°C at a rate of 20°C per minute in air. Preferred heat resistant polymer fibers have a yarn tenacity of at least 3 grams per denier (2.7 grams per decitex). Heat resistant polymer fibers include para-aramid fibers, aramid copolymer fibers, polybenzazole fibers, polybenzimidazole fibers, polyimide fibers, and mixtures thereof. A preferred heat resistant polymer fiber is para-aramid fiber, and a preferred para-aramid fiber is poly(paraphenylene terephthalamide fiber).

[0020] The at least one first yarn comprises at least 50 weight percent of the heat resistant polymeric fiber, based on the total weight of the first yarn. In some embodiments, the at least one first yarn comprises at least 60 weight percent of the heat resistant polymeric fiber, based on the total weight of the first yarn. In some embodiments, the at least one first yarn comprises 60-85 weight percent of the heat resistant polymeric fiber, based on the total weight of the first yarn, and in some other embodiments, the at least one first yarn comprises 60-80 weight percent of the heat resistant polymeric fiber, based on the total weight of the first yarn.

[0021] At least 30 weight percent of the polymeric fibers present in the at least one first yarn are cut resistant, heat resistant polymeric fibers having a cut resistance of 500 grams force or greater according to F2992-15. The cut performance of the fibers is determined by measuring the cut performance of a 10 ounce per square yard (345 grams per square meter) fabric woven or knitted from 100% of the fibers under test, and then the cut resistance (in grams force) is measured according to ASTM F2992-15.

[0022] Cut-resistant heat-resistant polymer fibers having a cut resistance of 500 grams force or more according to F2992-15 include para-aramid fibers, aramid copolymer fibers, polybenzazole fibers, polybenzimidazole fibers, and mixtures thereof. A preferred cut-resistant heat-resistant polymer fiber is para-aramid fiber, and a preferred para-aramid fiber is poly(paraphenylene terephthalamide fiber. When the heat-resistant polymer fiber has sufficient cut resistance, the cut-resistant heat-resistant polymer fiber in the at least one first yarn can be the same as or different from the heat-resistant polymer fiber in the at least one first yarn.

[0023] Thus, it is understood that cut-resistant heat-resistant polymer fibers are both heat-resistant polymer fibers as defined above and cut-resistant fibers as defined above. It is also understood that the at least one first yarn can include fibers that are heat-resistant polymer fibers as defined herein but are not cut-resistant fibers as defined herein. Table 1 provides an index standard showing selected exemplary compositions in terms of possible percentages of total heat-resistant (CH-HR) polymer fibers and total inorganic filaments in the at least one first yarn, and further provides possible percentages showing possible amounts of non-cut-resistant heat-resistant (non-CR-HR) polymer fibers and cut-resistant heat-resistant (CH-HR) polymer fibers.

[0024] [Table 1] It is therefore understood that at least 30 weight percent of the polymeric fibers present in the at least one first yarn are polymeric fibers that are both cut resistant and heat resistant as defined herein, in some embodiments, 50-85 weight percent of the at least one first yarn are cut resistant and heat resistant polymeric fibers.

[0025] In addition to the various exemplary percentages of cut-resistant and non-cut-resistant heat-resistant polymeric fibers shown in Table 1, in some embodiments, at least one first yarn further comprises other synthetic or organic fibers or filaments that are not heat-resistant polymeric fibers, i.e., they do not meet the definition of heat-resistant polymeric fibers provided herein. Essentially any type of fiber can be included, so long as the final fabric meets the composition described herein and the performance criteria discussed herein. Preferably, the fibers or filaments that are not heat-resistant polymeric fibers are organic fibers, and in some embodiments, polymeric organic fibers. Also, in some embodiments, when present, the fibers or filaments that are not heat-resistant polymeric fibers are organic or synthetic staple fibers.

[0026] In some preferred embodiments, in addition to the heat resistant fiber and the cut resistant heat resistant fiber, the at least one first yarn may further comprise a flame resistant fiber. By "flame resistant fiber" it is meant that a fabric made solely from the fabric has a char length of 4 inches or less and an afterflame time of 2 seconds or less according to the ASTM D6143-99 vertical burn test, but the fiber does not meet the cut resistance criteria previously set forth herein for cut resistant heat resistant polymeric fibers. Suitable flame resistant fibers include meta-aramid fibers, with a preferred meta-aramid being poly(metaphenylene isophthalamide). Potentially useful flame resistant fibers include meta-aramid, polyamideimide, flame retardant treated (FR) cellulose, FR cotton, FR lyocell, or mixtures thereof. In some embodiments, the at least one first yarn preferably has 10 to as much as 35 weight percent flame resistant fiber, based on the total weight of the polymeric fibers in the first yarn.

[0027] Both the heat-resistant polymer fiber and the cut-resistant heat-resistant polymer fiber in the at least one first yarn are preferably staple fibers having a length of about 2 to 20 centimeters, preferably about 3.5 to 6 centimeters. Both the heat-resistant polymer fiber and the cut-resistant heat-resistant polymer fiber in the at least one first yarn are preferably staple fibers having a diameter of 5 to 25 micrometers and a linear density of 0.5 to 7 decitex. Also, in some embodiments, fibers or filaments that are flame-resistant fibers or are not heat-resistant polymer fibers, if present, are staple fibers having dimensions similar to the above ranges of the heat-resistant polymer fiber and the cut-resistant heat-resistant polymer fiber.

[0028] In some embodiments, the inorganic fibers are present in an amount of 15-40 weight percent of the total weight of the first yarn. Similarly, the maximum amount of heat resistant polymeric fibers in these sheath-core first yarns is 85 weight percent based on the total weight of the first yarn. In some preferred embodiments, the sheath / core yarns have 60-80 weight percent heat resistant polymeric fibers in the sheath and 20-40 weight percent inorganic fibers in the core. Preferably, the core inorganic fibers are steel or tungsten. Preferably, the core inorganic fibers are present as one or more continuous filaments.

[0029] The sheath fibers can be wrapped or spun around the inorganic filament core. In particular, this can be accomplished by known means such as conventional ring spinning, including those utilizing COTSON technology, core-spun spinning such as DREF spinning, air jet spinning using so-called core insertion by Murata (now Muratec) jet-like spinning, open-end spinning, and other modifications of conventional processes. Preferably, the staple fibers are packed around the inorganic filament core with a density sufficient to cover the core. The coverage varies depending on the process used to spin the yarn, for example, core-spun spinning such as DREF spinning (disclosed, for example, in U.S. Pat. Nos. 4,107,909, 4,249,368, and 4,327,545) provides better coverage than ring spinning. Conventional ring spinning provides only partial coverage of the central core, but even partial coverage can provide adequate sheath / core coverage. The sheath may also contain some fibers of other materials, to the extent that the reduced cut resistance of the other materials is acceptable.

[0030] The incorporation of at least one inorganic filament as the core of the first yarn can be achieved, for example, in its simplest practical application, by passing a roving, sliver, or assembly of heat-resistant and cut-resistant fibers, and optionally non-heat-resistant fibers, through a set of draft rolls to ring-twist the drafted fiber mass into a single yarn. The at least one inorganic filament is typically fed from a bobbin through a set of feed rolls, and then fed into staple fibers before a final set of draft rollers. Since the inorganic core filament is not elastomeric, there is no need to apply excessive tension during insertion into the yarn, and only sufficient tension is applied to either the sheath fiber or the core, as is conventionally used.

[0031] At least one first yarn in the form of a sheath / core yarn generally comprises 15-50 weight percent inorganic filaments having a total linear sheath / core yarn density of 100-5000 decitex. The core comprising the inorganic fibers may be a single filament or may be multifilament, preferably a single metal filament or several metal filaments as required or desired for a particular application or degree of cut protection. By metal filament is meant a filament or wire made from a ductile metal such as stainless steel, copper, aluminum, bronze, tungsten, or a metal fiber structure commonly known as "micro-steel". Stainless steel is the preferred metal. Metal filaments are generally continuous wires. Useful metal filaments are 1-150 micrometers in diameter, preferably 25-75 micrometers in diameter.

[0032] In some embodiments, the inorganic fibers are glass filaments. The inorganic fibers can be one or more glass filaments, such as, for example, 110 decitex (100 denier) glass filaments. However, glass is less preferred because it is less cut-resistant per linear density than metal, and it is much more important that the glass is substantially covered with a sheath of short fibers to minimize skin irritation when the yarn is used in fabrics that contact the skin, such as gloves, sleeves, etc. Thus, in many embodiments, the inorganic fibers are metal filaments rather than glass filaments.

[0033] The at least one second yarn has a sheath / core construction with a sheath of halogenated self-extinguishing staple fibers and a core comprising at least one continuous elastomeric filament, where 60 to 95 weight percent of the at least one second yarn is halogenated self-extinguishing staple fibers, based on the total weight of the second yarn, the halogenated self-extinguishing fibers are in contact with the at least one continuous elastomeric filament, and the second yarn is free or substantially free of inorganic fibers.

[0034] The at least one second yarn has a sheath / core structure, with a sheath of halogenated self-extinguishing staple fibers in contact with and covering the core of the at least one continuous elastomeric filament. The halogenated self-extinguishing staple fibers are believed to provide an active flame-extinguishing coating for the core of the at least one continuous elastomeric filament. This is different from coated fibers that provide a "structural shield" for the core, i.e., coated fibers that readily char and stay in place when exposed to a flame, thus providing a structural barrier between the flame and the elastic core. Instead, the sheath of halogenated self-extinguishing staple fibers decomposes in the presence of a high heat flux, such as a flame, releasing halogen gas that locally drives oxygen out of the yarn and prevents the core of the at least one continuous elastomeric filament from burning. It is therefore believed that the halogenated self-extinguishing staple fibers should not only cover the core, but also be in direct contact with the core and locally drive oxygen away from the surface of the core of the at least one continuous elastomeric filament.

[0035] A sheath of halogenated self-extinguishing staple fibers can be wrapped or spun around at least one continuous elastomeric filament. This can be accomplished by known means such as conventional ring spinning, including modifications of conventional processes such as those utilizing COTSON technology, core-spun spinning such as DREF spinning, air jet spinning using so-called core insertion by Murata (now Muratec) jet-like spinning, open-end spinning, and the like. Preferably, the staple fibers are consolidated around a core of at least one continuous elastomeric filament with a density sufficient to cover the core. The coverage varies depending on the process used to spin the yarn, for example, core-spun spinning such as DREF spinning (disclosed, for example, in U.S. Pat. Nos. 4,107,909, 4,249,368, and 4,327,545) provides better coverage than ring spinning. Conventional ring spinning provides only partial coverage of the central core, but even partial coverage is assumed herein to be a possible sheath / core structure.

[0036] The flame extinguishing effect of the halogenated self-extinguishing staple fibers is considered adequate when 60-95 weight percent of the at least one second yarn is halogenated self-extinguishing fiber, based on the total weight of the second yarn. In some embodiments, it is desirable for 80-95 weight percent of the at least one second yarn to be halogenated self-extinguishing fiber, based on the total weight of the second yarn. The sheath can also include some fibers of other materials, to the extent that a reduction in the flame extinguishing effect due to the other materials is acceptable.

[0037] Halogenated self-extinguishing fibers include those made from halogenated polymers. One particularly preferred halogenated self-extinguishing fiber is a fiber made from a modacrylic polymer. By "modacrylic polymer" it is preferably meant that the polymer is a copolymer containing 30-70 weight percent acrylonitrile and 70-30 weight percent halogen-containing vinyl monomer. The halogen-containing vinyl monomer is at least one monomer selected from, for example, vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide, and the like.

[0038] In some embodiments, the modacrylic copolymer is of acrylonitrile combined with vinylidene chloride. In some embodiments, the modacrylic copolymer further comprises antimony oxide or antimony oxides. In some preferred embodiments, the modacrylic copolymer has less than 1.5 weight percent antimony oxide or antimony oxides, or the copolymer is completely free of antimony. By limiting or completely eliminating the amount of any antimony compounds added to the copolymer during manufacture, very low antimony content polymers and antimony free polymers can be made. Representative processes for modacrylic polymers, including those that can be modified in this manner, are disclosed in U.S. Pat. No. 3,193,602, which has 2 weight percent antimony trioxide; U.S. Pat. No. 3,748,302, which is made with various antimony oxides present in amounts of at least 2 weight percent, preferably no more than 8 weight percent; and U.S. Pat. Nos. 5,208,105 and 5,506,042, which have 8 to 40 weight percent antimony compounds. In some embodiments, the modacrylic polymer has an LOI of at least 26. In one preferred embodiment, the modacrylic polymer has an LOI of at least 26 but is antimony-free.

[0039] The halogenated self-extinguishing staple fibers in the at least one second yarn are preferably staple fibers having a length of about 2 to 9 centimeters, preferably about 3.5 to 6 centimeters. The halogenated self-extinguishing staple fibers in the at least one second yarn are preferably staple fibers having a diameter of 5 to 25 micrometers and a linear density of 0.5 to 7 decitex.

[0040] The ply yarn comprises at least one second yarn having a sheath / core structure with a sheath of halogenated self-extinguishing staple fibers and a core comprising at least one continuous elastomeric filament, the halogenated self-extinguishing fibers being in contact with the at least one continuous elastomeric filament, eliminating the need for the entire surface of this (these) elastomeric filament to actually be completely covered by the staple fiber sheath.

[0041] In some embodiments, it is preferred that at least 90% of the core is covered by the sheath as viewed under a microscope when the yarn is in a relaxed state, i.e., the sheath-core yarn is viewed in an untensioned state. The actual coverage of the core may vary depending on the degree of tension in the yarn, but it is believed that the modacrylic exerts its shielding effect as long as it is in contact with the elastomeric core.

[0042] In some embodiments, 5 to 40 weight percent of the total weight of the at least one second yarn is at least one continuous elastomeric filament. In some embodiments, the ring spun second yarn has a core comprising at least one elastomeric filament and a partial coverage of halogenated self-extinguishing staple fibers. In some preferred embodiments, the elastomeric filament core comprises 5 to 25 weight percent of the total sheath / core single yarn linear density of 100 to 1500 decitex.

[0043] As used herein, "core comprising at least one continuous elastomeric filament" means a core formed from or comprising an elastomeric filament, which preferably has the ability to rapidly return to its original length after repeated stretching and at least two more times. Preferred elastomeric cores include polyurethane-based yarns such as spandex or elastane, although generally any fiber having stretch and recovery properties can be used. Suitable well-known elastomeric yarns also include products sold under the trade names Dorlastan® and Lycra®.

[0044] The preferred at least one continuous elastomeric filament is a spandex fiber. As used herein, "spandex" has its usual definition, i.e., a manufactured fiber in which the fiber-forming material is a long-chain synthetic polymer composed of at least 85 weight percent segmented polyurethane. Among the spandex-type segmented polyurethanes are, for example, those described in U.S. Pat. Nos. 2,929,801, 2,929,802, 2,929,803, 2,929,804, 2,953,839, 2,957,852, 2,962,470, 2,999,839, and 3,009,901.

[0045] In some processes for making spandex elastomeric filaments, a coalescing jet is used to consolidate the spandex filaments immediately after extrusion. It is also well known that dry-spun spandex filaments are tacky immediately after extrusion. The combination of bringing together groups of such tacky filaments and using a coalescing jet produces a fused multifilament yarn, which is then typically coated with a silicone or other finish before winding to prevent sticking in the package. Such fused groupings of filaments, which are actually many very small individual filaments that adhere to each other along their length, are superior in many ways to single filaments of spandex of the same linear density.

[0046] The elastomeric filaments in the elastomeric singles yarn are preferably continuous filaments and may be present in the second yarn in the form of one or more individual filaments or in the form of one or more fused groupings of filaments. However, in preferred elastomeric singles yarns, it is preferred to use only one fused grouping of filaments. Whether present as one or more individual filaments or one or more fused groupings of filaments, the overall linear density of the elastomeric filaments in the relaxed state is generally 17 to 560 decitex (15 to 500 denier), with a preferred linear density range of 44 to 220 decitex (40 to 200 denier).

[0047] It is preferred to incorporate at least one continuous elastomeric filament under tension into the second yarn by stretching or stretching the at least one continuous elastomeric filament prior to combining with the staple fiber using a slower delivery rate of the at least one continuous elastomeric filament compared to the final second yarn speed, which can be described as a stretch ratio of the continuous elastomeric filament, which is the final second yarn speed divided by the delivery rate of the continuous elastomeric filament.

[0048] Typical stretch ratios are 1.5-5.0, with 1.5-3.50 being preferred. A low stretch ratio results in poor elastic recovery, while a very high stretch ratio makes the single yarn difficult to process and the fabric too tight and uncomfortable. The optimum stretch ratio also depends on the weight percent content of the elastomeric core. A tensioning device can also be used to tension and stretch the elastomeric fibers, but this is less preferred as the tension and stretch are difficult to reproduce and control. The optimum stretch ratio is ultimately determined for each fabric based on the desired fit and feel of the fabric.

[0049] Incorporation of at least one continuous elastomeric filament into a second yarn of halogenated self-extinguishing staple fibers can be accomplished, for example, in its simplest practical application, by passing a roving, sliver, or assembly of halogenated self-extinguishing staple fibers through a set of draft rolls and ring twisting the drafted fiber mass into a single yarn. At least one continuous elastomeric filament is typically fed from a bobbin through a set of feed rolls and then fed into the staple fiber before a final set of draft rollers. Using conventional techniques, the slow relative surface speed of the feed rollers to the surface speed of the draft rollers is increased or decreased to determine the amount of elastic stretch and tension in the final ring twisted single yarn.

[0050] In some embodiments, the sheath of at least one second yarn can further comprise a heat resistant polymer fiber as described hereinabove. In some other embodiments, the sheath of at least one second yarn can further comprise a cut resistant heat resistant polymer fiber as described hereinabove.

[0051] In some embodiments, the sheath of at least one second yarn can further comprise a flame-resistant fiber. By "flame-resistant" fiber, it is meant that a fabric made solely from that fabric has a char length of 4 inches or less and an after-flame time of 2 seconds or less according to the ASTM D6143-99 vertical burn test. Suitable flame-resistant fibers include aramid fibers, with meta-aramid fibers being particularly preferred, and a preferred meta-aramid being poly(metaphenylene isophthalamide). Potentially useful flame-resistant fibers include meta-aramid, polyamideimide, flame retardant treated (FR) cellulose, FR cotton, FR lyocell, or mixtures thereof. Any number of fibers can be included in the second yarn, so long as the second yarn and final fabric meet the performance criteria discussed herein.

[0052] When used in the second yarn, the heat resistant polymer fiber, the cut resistant heat resistant polymer fiber, or the flame resistant fiber is preferably a staple fiber having a length of about 2 to 20 centimeters, preferably about 3.5 to 6 centimeters. Also, when used in the second yarn, the heat resistant polymer fiber, the cut resistant heat resistant polymer fiber, and the flame resistant fiber are preferably staple fibers having a diameter of 5 to 25 micrometers and a linear density of 0.5 to 7 decitex.

[0053] In some embodiments, the sheath of the at least one second yarn may further comprise what is known in the art as antistatic fibers, or fibers that have the ability to reduce the accumulation of charge in the yarn or in the resulting fabric. In some preferred embodiments, the sheath of the at least one second yarn comprises at least 1-5 weight percent of antistatic fibers, based on the total weight of the at least one second yarn. Preferred antistatic fibers are those that function due to the presence of carbon in the fiber, either as a carbon coating or carbon particles, particularly antistatic fibers that help eliminate the accumulation of charge, but are not considered to be conductive in the true sense. In some embodiments, aramid fibers with carbon particles are preferred.

[0054] The second yarn is free or substantially free of inorganic fibers, and the cut resistance advantage of the ply yarn is provided by the first yarn, obviating the need for additional inorganic fibers in the second yarn for most intended applications.

[0055] A ply yarn is formed from at least a first yarn and at least a second yarn. A ply yarn is made by twisting together at least two individual single yarns. The phrase "twisting together at least two individual single yarns" means that two single yarns are twisted together without one yarn completely covering the other. This distinguishes a ply yarn from a covered or wrapped yarn in which a first single yarn is substantially or completely wrapped around a second single yarn, ideally with only the first single yarn exposed on the surface of the resulting covered yarn.

[0056] In one preferred embodiment, the ply yarn is made from at least two single yarns, the first single yarn being (a) at least one first yarn comprising at least 50 weight percent heat resistant polymeric fiber, based on a total weight of the first yarn, wherein at least 30 weight percent of the polymeric fiber present in the at least one first yarn is cut resistant, heat resistant polymeric fiber having a cut resistance of 500 grams force or greater according to F2992-15, the at least one first yarn comprising a sheath comprising cut resistant, heat resistant polymeric fiber and a core comprising inorganic fiber. and the second single yarn further comprises (b) at least one second yarn having a sheath / core structure with a sheath of halogenated self-extinguishing staple fibers and a core comprising at least one continuous elastomeric filament, wherein 60 to 95 weight percent of the at least one second yarn is halogenated self-extinguishing fiber, based on the total weight of the second yarn, the halogenated self-extinguishing fiber is in contact with the at least one continuous elastomeric filament, and the second yarn is free or substantially free of inorganic fibers. Each of the single yarns may have some twist.

[0057] In some embodiments, a ply yarn made from two single yarns has a total linear density of 200 to 3000 dtex. Any individual staple fiber of the single yarn can have a linear density of 0.5 to 7 dtex, with a preferred linear density range of 1.5 to 3 dtex. The ply yarns, and the single yarns that make up those ply yarns, can contain other materials so long as the function or performance of the yarn or the fabric made from that yarn is not compromised for the desired use.

[0058] Plyed yarns can be made from single yarns by the process disclosed in U.S. Patent No. 6,952,915 to Prickett, and the plyed yarns can have a wide range of plying as disclosed therein. For example, either a two-step process or a combined process can be used. In the first step of the two-step process, two or more single yarns are combined parallel to each other without plying and wound into a package. In the next step, the two or more combined single yarns are then ring-twisted together using a reverse twist of the single yarns (if there is any twist) to form the plyed yarn. Plyed yarns typically have a "Z" twist and single yarns typically have an "S" twist. Alternatively, single yarns can be plyed using a combined process that combines both of these steps in one operation. Equipment commonly used to ply single yarns is available from equipment manufacturers such as Volkmann and Muratec (formerly Murata).

[0059] The ply yarns can then be combined with other same or different ply yarns to form yarn bundles to form fabrics, or individual ply yarns can be used to form fabrics, depending on the requirements of the desired fabric. For example, two or more of the described ply yarns can be combined to form yarn bundles that can be fed to a knitting machine with or without twist. Alternatively, yarn bundles can be made using one or more of the above ply yarns with one or more different single yarns to impart desired properties to the final fabric. Since modern knitting machines can knit fabrics by feeding multiple ply yarns, it is not necessary to add twist to the bundles of ply yarns fed to the knitting machine, but twist can be added to the bundles if desired.

[0060] At least the first yarn used in the preferred ply yarn preferably has a poly(paraphenylene terephthalamide) (PPD-T) staple sheath, the PPD-T having a cut length of 3.8 cm (1.5 inches) and a filament density of 1.7 dtex per filament (1.5 denier per filament). The staple sheath can be in the form of a 14-29 cotton count yarn.

[0061] At least one second yarn used in the preferred ply yarns is a ring spun 330 dtex (295 denier, equivalent to 18 cotton count) single yarn. The single yarn has a modacrylic staple sheath at least partially covering an elastomeric core filament, the modacrylic staple having a cut length of 4.8 cm (1.89 inches) and a filament density of 1.7 dtex per filament (1.5 denier per filament). The elastomeric core is a 78 dtex (70 denier) spandex fused filament yarn having a stretch ratio of 3.0 (approximately 200 percent elongation). In some preferred embodiments, approximately 92 percent by weight of the second yarn is composed of modacrylic staple fiber and 8 percent by weight of the second yarn is elastomeric core.

[0062] The present invention also relates to cut resistant woven or knitted fabrics made from ply-ply yarns or yarn bundles including ply-ply yarns, the ply-ply yarns including at least one first yarn and at least one second yarn as described herein.

[0063] Specifically, the present invention relates to a cut resistant woven or knitted fabric made from a ply yarn made from at least two single yarns, the first single yarn being (a) at least one first yarn comprising at least 50 weight percent heat resistant polymeric fiber, based on a total weight of the first yarn, wherein at least 30 weight percent of the polymeric fiber present in the at least one first yarn is cut resistant, heat resistant polymeric fiber having a cut resistance of 500 grams force or greater according to F2992-15, the at least one first yarn comprising a sheath comprising the cut resistant, heat resistant polymeric fiber and and (b) at least one second yarn having a sheath / core structure with a core comprising inorganic fibers, the second single yarn being (a) at least one second yarn having a sheath / core structure with a sheath of halogenated self-extinguishing staple fibers and a core comprising at least one continuous elastomeric filament, wherein 60 to 95 weight percent of the at least one second yarn is halogenated self-extinguishing fiber, based on the total weight of the second yarn, the halogenated self-extinguishing fiber is in contact with the at least one continuous elastomeric filament, and the second yarn is free or substantially free of inorganic fibers. Preferably, the cut resistant woven or knitted fabric has a maximum afterflame time of 2 seconds or less and a weight loss of 5 weight percent or less when tested according to NFPA-2112-2018.

[0064] The at least one first yarn and the at least one second yarn act synergistically together in the ply yarn, with at least one continuous elastomeric filament incorporated in the yarn providing improved stretch and recovery, while the heat resistant staple fibers provide structure in a flame, and the heat resistant cut resistant organic staple fibers and inorganic filaments provide excellent cut resistance to the fabric. Fabrics made from such yarns are soft, comfortable, non-abrasive, and cut resistant.

[0065] Plying the first and second yarns helps to hold the elastomeric single yarn in an elongated state without looping on itself when relaxed. Additionally, control of yarn tension during knitting and weaving is less important when the bundle is constructed from plied yarns.

[0066] Woven and / or knitted fabrics can include the ply yarns described herein. Preferred woven and knitted fabrics have a maximum afterflame time of 2 seconds or less and a weight loss of 5 weight percent or less when tested according to NFPA-2112-2018.

[0067] The preferred fabric is a knitted fabric, with any suitable knit pattern being acceptable. Cut resistance and comfort are affected by the tightness of the knitted fabric, which can be adjusted to meet any particular need. Highly effective combinations of cut resistance and comfort in many cut resistant articles have been found, for example, in single jersey and terry knit patterns. Preferably, the fabric is about 4 to 30 oz / yd. 2 , preferably 6 to 25 ounces per yard 2 , the fabric is at the high end of the basis weight range that offers greater heat and cut protection.

[0068] An article can include the ply yarns described herein, or an article can be made from the aforementioned fabrics that include the ply yarns described herein. Particularly useful articles include gloves, sleeves, and aprons.

[0069] Test Method Afterflame and weight loss were determined in accordance with NFPA 2112-2018, Standard on Flame-Resistant Clothing for Protection of Industrial Personnel Against Short-Duration Thermal Exposures from Fire, specifically the procedures outlined in Section 8.8 of the standard.

[0070] Determination of "heat resistant polymer fibers" as discussed herein can be accomplished by using ASTM E2105-2016-Standard Practice for General Techniques of Thermogravimetric Analysis (TGA) Coupled With Infrared Analysis (TGA / IR). Analysis of whether a synthetic organic polymer retains 90 percent of its original fiber weight is performed by heating the sample in air at a rate of 20°C per minute to 500°C. EXAMPLES

[0071] Plyed yarns and knits made from the yarns are illustrated in Examples 1, 2, 3 and Comparative Example A and are summarized in Table 5.

[0072] Example 1 The ply elastic yarn was made by plying a first yarn with a second yarn.

[0073] The first yarn was a 14 cotton count sheath-core yarn with a para-aramid fiber sheath and a 50 micron stainless steel wire core, spun on a ring spinning frame. The para-aramid fiber was 2 inch poly(paraphenylene terephthalamide) staple fiber.

[0074] The second yarn was an 18 cotton count sheath-core yarn made by core spinning on a ring spinning frame of 2 inch modacrylic staple fiber around a 70 denier spandex core, where the spandex core was stretched 3 times when incorporated (spun) into the sheath-core yarn.

[0075] The resulting ply elastic yarn, made by plying the first and second yarns, had a total cotton count of 16 / 2, or denier 675. The relative amounts of the yarn components are shown in Table 2.

[0076] The resulting ply elastic yarn was knitted into a 13 gauge sleeve on a Shima-Seiki glove knitting machine. The resulting sleeve had excellent hand fit and conformability. Fabric samples from the resulting sleeve were flame tested according to the fire-resistant glove test method detailed in the NFPA-2112-2018 standard. The resulting stretch fabric was found to have a 0 second afterflame with 4.8% of the weight consumed during the test, which was below the 2 second maximum afterflame requirement and 5% weight loss limit allowed by the specification.

[0077] [Table 2] Example 2 The ply elastic yarn of Example 1 was repeated with the following exceptions: The first yarn was a 26 cotton count yarn with a para-aramid fiber sheath and a stainless steel wire core made of a 35 micron stainless steel wire core. The second yarn was a 32 cotton count yarn with a modacrylic sheath and a 40 denier spandex core that was stretched 3 times during spinning.

[0078] The resulting ply elastic yarn, made by plying the first and second yarns as in Example 1, had a total cotton count of 29 / 2, or 371 denier. The relative amounts of the yarn components are shown in Table 3.

[0079] The resulting ply elastic yarn was knitted into an 18 gauge sleeve on a Shima-Seiki glove knitting machine. The resulting sleeve had excellent form fit. Fabric samples from the resulting sleeve were washed to remove knitting oils and finishes and flame tested according to the fire resistant glove test method detailed in the NFPA-2112-2018 standard. The resulting stretch fabric was found to have a 0 second afterflame with 3.3% of the weight consumed during testing, which was below the 2 second maximum afterflame requirement and 5% weight loss limit allowed by the specification.

[0080] [Table 3] Example 3 The ply elastic yarn of Example 1 was repeated with the following exceptions.

[0081] The first yarn was a 19.5 cotton count yarn with a para-aramid fiber sheath and a stainless steel wire core made of a 45 micron stainless steel wire core. The second yarn was a 32 cotton count sheath-core yarn with a 40 denier spandex core stretched 3 times during spinning, but the sheath was a blend of 82% by weight modacrylic staple fiber and 10% by weight 2 inch cut length meta-aramid staple fiber blend, specifically the meta-aramid blend included 93% by weight poly(metaphenylene isophthalamide) staple fiber, 5% by weight poly(paraphenylene terephthalamide) staple fiber, and 2% by weight carbon-core nylon antistatic fiber.

[0082] The resulting ply elastic yarn, made by plying the first and second yarns as in Example 1, had a total cotton count of 24 / 2, or 439 denier. The relative amounts of the yarn components are shown in Table 4.

[0083] The resulting ply elastic yarn was knitted into an 18 gauge sleeve on a Shima-Seiki glove knitting machine. The resulting sleeve had excellent form fit.

[0084] The resulting sleeve fabric samples produced were washed to remove knitting oils and finishes and then flame tested according to the fire resistant glove test method detailed in the NFPA-2112-2018 standard. The resulting stretch fabric was found to have a 0 second afterflame with 3.9% of its weight consumed during testing, which was below the 2 second maximum afterflame requirement and 5% weight loss limit allowed by the specification.

[0085] Another fabric sample of the produced sleeve was flame tested according to the fire resistant glove test method detailed in the EN407:2020 standard. The resulting stretch fabric was found to have 0 seconds of afterflame and 0 seconds of afterglow after 3 and 15 seconds of exposure to flame, which was below the maximum afterflame and 5 second afterglow requirements allowed by the specification.

[0086] [Table 4] Comparative example A Comparative ply elastic yarns similar to that of Example 3 were made, but with a para-aramid fiber sheath and a stainless steel wire core. The first yarn was made with 1.5 inch poly(paraphenylene terephthalamide) staple fiber and a 45 micron stainless steel wire core. The second yarn was again a 32 cotton count sheath-core yarn, but had a cut length of 1.5 inch nylon staple fiber core-spun only sheath around a 40 denier spandex core.

[0087] The resulting 24's-2 count ply elastic yarn was knitted into an 18 gauge sleeve on a Shima-Seiki glove knitting machine. The resulting sleeve had excellent form fit.

[0088] However, the produced samples were flame tested according to the fire resistant glove test method detailed in the EN407:2020 standard, and the resulting stretch fabric was found to have at least a 25 second afterflame after 3 seconds of exposure to flame, which was higher than the maximum afterflame requirement of 20 seconds to achieve even the minimum rank stated in the specification.

[0089] Subsequent testing was not performed after either the 15 second exposure in the EN407 test or the 12 second exposure in the NFPA-2112 test due to excessive afterflame after only 3 seconds of flame exposure.

[0090] [Table 5]

Claims

1. (a) at least one first yarn comprising at least 50 weight percent heat resistant polymeric fibers, wherein at least 30 weight percent of the polymeric fibers present in the at least one first yarn are cut resistant heat resistant polymeric fibers having a cut resistance of 500 grams force or greater according to ASTM F2992-15; (b) at least one second yarn having a sheath / core construction with a sheath of halogenated self-extinguishing staple fibers and a core comprising at least one continuous elastomeric filament, 1. A ply yarn, comprising: 60 to 95 weight percent of said at least one second yarn being halogenated self-extinguishing fiber, said halogenated self-extinguishing fiber being in contact with said at least one continuous elastomeric filament, said second yarn being free or substantially free of inorganic fibers.

2. 10. The ply yarn of claim 1, wherein the at least one first yarn has a sheath / core construction with a sheath comprising the cut resistant, heat resistant polymeric fibers and a core comprising inorganic fibers.

3. 3. The ply yarn of claim 1 or 2, wherein the heat resistant polymer fiber or the cut resistant heat resistant polymer fiber is an aramid copolymer, para-aramid, polybenzazole, polybenzimidazole, polyimide or mixtures thereof.

4. The ply yarn of any one of claims 1 to 3, wherein the at least one first yarn further comprises flame resistant fibers that are not cut resistant.

5. 5. The ply yarn of claim 4, wherein the flame resistant fiber is meta-aramid, polyamideimide, flame retardant treated (FR) cellulose, FR cotton, FR lyocell, or mixtures thereof.

6. 6. The ply yarn of claim 5, wherein said flame resistant fiber is a meta-aramid.

7. 7. The ply yarn of any one of claims 1 to 6, wherein 80 to 95 weight percent of the total weight of the at least one second yarn is the halogenated self-extinguishing fiber.

8. The ply yarn of any one of claims 1 to 7, wherein the halogenated self-extinguishing fibers are modacrylic fibers.

9. The ply yarn of any one of claims 1 to 8, wherein the inorganic fibers are metal filaments.

10. The ply yarn of any one of claims 1 to 9, wherein the sheath of the at least one second yarn further comprises heat resistant polymeric fibers.

11. 11. The ply yarn of any one of claims 1 to 10, wherein the sheath of the at least one second yarn further comprises flame resistant fibers that are not cut resistant.

12. 12. The ply yarn of claim 11, wherein the flame resistant fiber is a meta-aramid, a polyamideimide, or a mixture thereof.

13. A woven or knitted fabric comprising the ply yarn of any one of claims 1 to 12.

14. 14. An article comprising the woven or knitted fabric of claim 13.

15. 15. The article of claim 14 in the form of a glove, sleeve, or apron.

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