Patent Application
20230346061
Embodiments of the present invention relate to flame resistant fabrics that are thermally stable despite having yarns with thermally stable fibers provided in only one direction of the fabric.
Many occupations can potentially expose an individual to electrical arc flash and/or flames. Workers who may be exposed to accidental electric arc flash and/or flames risk serious burn injury unless they are properly protected. To avoid being injured while working in such conditions, these individuals typically wear protective garments constructed of flame resistant materials designed to protect them from electrical arc flash and/or flames. Such protective clothing can include various garments, for example, coveralls, pants, and shirts.
Standards have been promulgated that govern the performance of such garments (or constituent layers or parts of such garments) to ensure that the garments sufficiently protect the wearer in hazardous situations. Fabrics from which such garments are constructed, and consequently the resulting garments as well, are required to pass a variety of safety and/or performance standards. NFPA 2112 (Standard on Flame-Resistant Clothing for Protection of Industrial Personnel Against Flash Fire, 2023 edition, incorporated herein by reference) governs the required performance of industrial worker garments that protect against flash fires. NFPA 1975 (Standard on Emergency Services Work Apparel, 2019 edition, incorporated herein by reference) governs the required performance of station wear worn by firefighter's in the firehouse and under turnout gear.
NFPA 2112 and NFPA 1975 require that the garments and/or individual layers or parts thereof pass a number of different performance tests, including compliance with the thermal protective requirements of having a char length of 4 inches (˜100 mm) or less (NFPA 2112) or 6 inches (˜150 mm) or less (NFPA 1975) and of having a two second or less after flame, when measured pursuant to the testing methodology set forth in ASTM D6413 (Standard Test Method for Flame Resistance of Textiles, 2022 edition, incorporated herein by reference).
To test for char length and after flame, a fabric specimen is suspended vertically over a flame for twelve seconds. The fabric must self-extinguish within two seconds (i.e., it must have a 2 second or less after flame). After the fabric self-extinguishes, a specified amount of weight is attached to the fabric and the fabric lifted so that the weight is suspended from the fabric. The fabric will typically tear along the charred portion of the fabric. The length of the tear (i.e., the char length) must be 4 inches or less (ASTM 2112) or 6 inches or less (NFPA 1975) when the test is performed in both the machine/warp and cross-machine/weft directions of the fabric. A fabric sample is typically tested for compliance both before it has been washed (and thus when the fabric still contains residual—and often flammable—chemicals from finishing processes) and after a certain number of launderings (e.g., 100 launderings for NFPA 2112).
NFPA 2112 and NFPA 1975 also contain requirements relating to the extent to which the fabric shrinks when subjected to heat. To conduct thermal shrinkage testing, marks are made on the fabric a distance from each other in both the machine/warp and cross-machine/weft directions. The distance between sets of marks is noted. The fabric is then suspended in a 500 degree Fahrenheit oven for 5 minutes. The distance between sets of marks is then re-measured. The thermal shrinkage of the fabric is then calculated as the percentage that the fabric shrinks in both the machine/warp and cross-machine/weft directions and must be less than the percentage set forth in the applicable standard. For example, NFPA 2112 and NFPA 1975 require that fabrics used in the construction of flame resistant garments exhibit thermal shrinkage of no more than 10% in both the machine/warp and cross-machine/weft directions before and after pre-treatment pursuant to ASTM F 2894 (Standard Test Method for Evaluation of Materials, Protective Clothing, and Equipment for Heat Resistance Using a Hot Air Circulating Oven, 2021 edition, incorporated herein by reference).
Conventional wisdom is that thermally stable fibers must be provided in both fabric directions to render a fabric thermally stable. Thus, historically flame resistant fabrics capable of complying with the thermal protective and thermal shrinkage requirements of NFPA 2112 and NFPA 1975 (particularly the thermal shrinkage requirements) have been formed of thermally stable yarns (i.e., yarns having thermally stable fibers) provided in both directions of the fabric. Such fibers tend to be expensive and thus the need to include them in both fabric directions elevates the cost of these fabrics. There is a need for a comfortable, inexpensive fabric that affords the requisite thermal protection and stability.
The terms “invention,” “the invention,” “this invention” and “the present invention” used in this patent are intended to refer broadly to all of the subject matter of this patent and the patent claims below. Statements containing these terms should not be understood to limit the subject matter described herein or to limit the meaning or scope of the patent claims below. Embodiments of the invention covered by this patent are defined by the claims below, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to the entire specification of this patent, all drawings and each claim.
Embodiments of the present invention relate to flame resistant fabrics that comply with applicable thermal requirements (e.g., char length, after flame, thermal shrinkage, etc.) but only include thermally stable fibers in yarns extending in a single fabric direction (warp or weft). The yarns extending in the other direction (warp or weft) are devoid of thermally stable fibers.
The subject matter of embodiments of the present invention is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described. All references to percentages (“%”) throughout are to weight percentages (“wt. %”). The terms “weft” and “fill” are used interchangeably herein. All references to standards and test/treatment methodologies are incorporated herein by reference.
Embodiments of the present invention relate to flame resistant fabrics that comply with applicable thermal requirements (e.g., char length, after flame, thermal shrinkage, etc.) but only include thermally stable fibers in yarns extending in a single fabric direction (warp or weft). The yarns extending in the other direction (warp or weft) are devoid of thermally stable fibers.
Some embodiments of the thermally stable, flame resistant fabrics described herein are formed by a first group of yarns and a second group of yarns, whereby each yarn group has a different fiber blend. In some embodiments, the fabric is formed only of the first group of yarns and the second group of yarns (i.e., these two yarn types form the entirety of the fabric). In other embodiments, yarns in addition to the first and second groups of yarns may be incorporated into the fabric.
In some embodiments, the yarns of the first group of yarns (‘first yarns”) are spun yarns having a fiber blend that includes thermally stable fibers, meaning that the fibers are able to resist thermal shrinkage and thermal degredation. The thermally stable fibers will often, but may not always, be inherently flame resistant fibers. In some embodiments, the first yarns include thermally stable fibers in a weight percentage from about 1% weight percent (“wt. %”) to about 30 wt. %, from about 2 wt. % to about 25 wt. %, from about 5 wt. % to about 25 wt. %, from about 8 wt. % to about 20 wt. %, from about 10 wt. % to about 20 wt. %, from about 15 wt. % to about 20 wt. %, and from about 2 wt. % to about 10 wt. %. In some embodiments, the thermally stable fibers constitute less than approximately 30%, less than approximately 25%, less than approximately 20%, less than approximately 15%, less than approximately 10%, and/or less than approximately 5% of the fiber blend of the first yarns.
Examples of suitable thermally stable fibers include, but are not limited to, para-aramid fibers, meta-aramid fibers, polybenzoxazole (“PBO”) fibers, polybenzimidazole (“PBI”) fibers, poly{2,6-diimidazo[4,5-b:40; 50-e]-pyridinylene-1,4(2,5-dihydroxy)phenylene} (“PIPD”) fibers, polyacrylonitrile (PAN) fibers, liquid crystal polymer fibers, glass fibers, carbon fibers, TANLON™ fibers (available from Shanghai Tanlon Fiber Company), melamine fibers (such as BASOFIL™, available from Basofil Fibers), polyetherimide fibers, pre-oxidized acrylic fibers, polyamide-imide fibers such as KERMEL™, polytetrafluoroethylene fibers, polyetherimide fibers, polyimide fibers, polyimide-amide fibers, liquid crystal polymer fibers and any combination or blend thereof. Examples of para-aramid fibers include KEVLAR™ (available from DuPont), TECHNORA™ (available from Teijin Twaron BV of Arnheim, Netherlands), and TWARON™ (also available from Teijin Twaron BV), and Taekwang para-aramid (available from Taekwang Industries). Examples of meta-aramid fibers include NOMEX™ (available from DuPont), CONEX™ (available from Teijin), APYEIL™ (available from Unitika), ARAWIN (available from Toray). An example of a liquid crystal polymer fiber is Vectran™ fibers available from Kuraray.
Most modacrylic and acrylic fibers are not considered thermally stable fibers. However, some have been rendered thermally stable (e.g., PyroTex® available from PyroTex Industries GmbH) and thus could be used as the thermally stable fiber component in the first yarns. However, for purposes of this application, modacrylic fibers are considered to be non-thermally stable fibers unless otherwise indicated.
The same thermally stable fibers may be used in the first yarns, but such is not a requirement. Rather, the fiber blend of the first yarns may include the same type of thermally stable fibers or, alternatively, different types of thermally stable fibers may be provided in the blend. In some embodiments, a blend of meta-aramid and para-aramid fibers are used in the first yarns.
In some embodiments, the first yarns include a blend of thermally stable fibers (such as, but not limited to, aramid fibers (meta-aramid, para-aramid, or both)) and modacrylic fibers (e.g., PROTEX™ fibers available from Kaneka Corporation of Osaka, Japan). The modacrylic fibers are significantly less expensive than the aramid fibers, thus helping to contain the cost of the fabric. In some embodiments the percentage of modacrylic fibers in the fiber blend of the first yarns is up to 2 times, up to 3 times, up to 4 times, up to 5 times, up to 6 times, up to 7 times, and/or up to 8 times the percentage of thermally stable fibers in the blend. In some embodiments, the first yarns include at least 30 wt. % modacrylic fibers, at least 35 wt. % modacrylic fibers, at least 40 wt. % modacrylic fibers, at least 45 wt. % modacrylic fibers, at least 50 wt. % modacrylic fibers, at least 55 wt. % modacrylic fibers, and/or at least 60 wt. % modacrylic fibers. In some embodiments, the first yarns include at least 40 wt. % modacrylic fibers and less than 60 wt. % modacrylic fibers. In some embodiments, the first yarns include approximately or about (i) 30-60 wt. % modacrylic fibers, inclusive; (ii) 35-55 wt. % modacrylic fibers, inclusive; (iii) 40-55 wt. % modacrylic fibers, inclusive; (iv) 40-50 wt. % modacrylic fibers, inclusive; (v) 45-55 wt. % modacrylic fibers, inclusive; and/or (vi) 45-50% modacrylic fibers, inclusive.
In some embodiments, cellulosic fibers may be added to the fiber blend of the first yarns to reduce cost and impart comfort. In some embodiments, the first yarns include at least 15 wt. % cellulosic fibers, at least 20 wt. % cellulosic fibers, at least 25 wt. % cellulosic fibers, at least 20 wt. % cellulosic fibers, at least 25 wt. % cellulosic fibers, at least 30 wt. % cellulosic fibers, at least 35 wt. % cellulosic fibers, at least 40 wt. % cellulosic fibers, at least 45 wt. % cellulosic fibers, or at least 50 wt. % cellulosic fibers. In some embodiments, the first yarns include approximately or about (i) 15-50 wt. % cellulosic fibers, inclusive; (ii) 20-45 wt. % cellulosic fibers, inclusive; (iii) 25-40 wt. % cellulosic fibers, inclusive; (iv) 30-45 wt. % cellulosic fibers, inclusive; (v) 30-40 wt. % cellulosic fibers, inclusive; (vi) 35-45 wt. % cellulosic fibers, inclusive; and/or (vii) 35-40 wt. % cellulosic fibers, inclusive.
In some embodiments, the cellulosic fibers are cotton fibers and/or lyocell fibers. In some embodiments, blends of different cellulosic fibers are used. While the cellulosic fibers can be treated so as to be flame resistant, this is not necessary. Rather, inclusion of the modacrylic fibers controls and counteracts the flammability of the cellulosic fibers to prevent the cellulosic fibers from burning. In this way, the cellulosic fibers (or the yarns or fabrics made with such fibers) need not be treated with a FR compound or additive.
In some embodiments, the first yarns include approximately or about (i) 2-25 wt. % thermally stable (e.g., aramid) fibers, 30-60 wt. % modacrylic fibers, and 15-50 wt. % cellulosic fibers (FR and/or non-FR), inclusive; (ii) 5-25 wt. % thermally stable (e.g., aramid) fibers, 35-55 wt. % modacrylic fibers, and 20-45 wt. % cellulosic fibers (FR and/or non-FR), inclusive; (iii) 8-20 wt. % thermally stable (e.g., aramid) fibers, 40-55 wt. % modacrylic fibers, and 30-45 wt. % cellulosic fibers (FR and/or non-FR), inclusive; (iv) 10-20 wt. % thermally stable (e.g., aramid) fibers, 40-50 wt. % modacrylic fibers, and 30-40 wt. % cellulosic fibers (FR and/or non-FR), inclusive; (v) 15-20 wt. % thermally stable (e.g., aramid) fibers, 45-55 wt. % modacrylic fibers, and 35-45 wt. % cellulosic fibers (FR and/or non-FR), inclusive.
In some embodiments, the fiber blend of the first yarns includes more modacrylic and/or cellulosic fibers than thermally stable fibers. In some embodiments, the fiber blend of the first yarns includes more modacrylic than cellulosic fibers. In some embodiments, the modacrylic fibers and the cellulosic fibers of the first fiber blend collectively constitute at least 50%, at least 60%, at least 70%, and/or at least 80% of the fiber blend of the first yarns.
In some embodiments, the yarns of the second group of yarns (‘second yarns”) are spun yarns having a fiber blend that is devoid of any of the thermally stable fibers identified above, including but not limited to aramid fibers. In some embodiments, the second yarns are formed exclusively of fibers that are not considered thermally stable, meaning that the fibers are not able to resist thermal shrinkage and thermal degradation (i.e., the fibers shrink, char, burn, melt, drip, etc.). Suitable fibers for the second yarns include, but are not limited to, natural and synthetic cellulosic fibers (e.g., cotton, rayon, acetate, triacetate, and lyocell, as well as their flame resistant counterparts FR cotton, FR rayon, FR acetate, FR triacetate, and FR lyocell), modacrylic fibers, wool, TANLON™ fibers (available from Shanghai Tanlon Fiber Company), nylon fibers, polyester fibers, polyolefin fibers (e.g., polypropylene, polyethylene, ultra high molecular weight polyethylene), etc., and blends thereof. An example of FR rayon fibers is Lenzing FR™ fibers, also available from Lenzing Fibers Corporation, and VISIL™ fibers, available from Sateri. Examples of lyocell fibers include TENCEL™, TENCEL G100™ and TENCEL A100™ fibers, all available from Lenzing Fibers Corporation. An example of a polyester fiber is DACRON® fibers (available from Invista™). Examples of suitable modacrylic fibers are PROTEX™ fibers available from Kaneka Corporation of Osaka, Japan.
The second yarns preferably include cellulosic fibers. In some embodiments, the second yarns include at least 10 wt. % cellulosic fibers, at least 20 wt. % cellulosic fibers, at least 30 wt. % cellulosic fibers, at least 40 wt. % cellulosic fibers, at least 50 wt. % cellulosic fibers, and/or at least 60 wt. % cellulosic fibers. In some embodiments, the second yarns include approximately or about (i) 30-70 wt. % cellulosic fibers, inclusive; (ii) 35-55 wt. % cellulosic fibers, inclusive; (iii) 40-60 wt. % cellulosic fibers, inclusive; (iv) 40-55 wt. % cellulosic fibers, inclusive; (v) 40-50 wt. % cellulosic fibers, inclusive; (vi) 45-55 wt. % cellulosic fibers, inclusive; (vii) 45-50 wt. % cellulosic fibers, inclusive; and/or (viii) 50-55 wt. % cellulosic fibers, inclusive.
In some embodiments, the cellulosic fibers are cotton fibers and/or lyocell fibers, which can be FR and/or non-FR. In some embodiments, blends of different cellulosic fibers are used in the fiber blend of the first yarns. While the cellulosic fibers can be treated so as to be flame resistant, this is not necessary. Rather, inclusion of the modacrylic fibers controls and counteracts the flammability of the cellulosic fibers to prevent the cellulosic fibers from burning. In this way, the cellulosic fibers (or the yarns or fabrics made with such fibers) need not be treated with a FR compound or additive.
In some embodiments, the second yarns include a blend of cellulosic fibers and modacrylic fibers. In some embodiments, the second yarns include at least 30 wt. % modacrylic fibers, at least 35 wt. % modacrylic fibers, at least 40 wt. % modacrylic fibers, at least 45 wt. % modacrylic fibers, at least 50 wt. % modacrylic fibers, at least 55 wt. % modacrylic fibers, at least 60 wt. % modacrylic fibers, at least 65 wt. % modacrylic fibers, and/or at least 70 wt. % modacrylic fibers. In some embodiments, the second yarns include at least 40 wt. % modacrylic fibers and less than 60 wt. % modacrylic fibers. In some embodiments, the second yarns include approximately or about (i) 40-70 wt. % modacrylic fibers, inclusive; (ii) 45-65 wt. % modacrylic fibers, inclusive; (iii) 45-60 wt. % modacrylic fibers, inclusive; (iv) 40-55 wt. % modacrylic fibers, inclusive; (v) 40-50 wt. % modacrylic fibers, inclusive; (vi) 45-55 wt. % modacrylic fibers, inclusive; and/or (vii) 45-50% modacrylic fibers, inclusive.
In some embodiments, the second group of yarns includes approximately or about (i) 30-70 wt. % modacrylic fibers and 30-70 wt. % cellulosic fibers (FR and/or non-FR), inclusive; (ii) 40-60 wt. % modacrylic fibers and 40-60 wt. % cellulosic fibers (FR and/or non-FR), inclusive; (iii) 45-55 wt. % modacrylic fibers and 45-55 wt. % cellulosic fibers (FR and/or non-FR), inclusive; and/or (iv) 50 wt. % modacrylic fibers and 50 wt. % cellulosic fibers (FR and/or non-FR), inclusive.
In some embodiments, the modacrylic fibers and cellulosic fibers of the second yarns collectively constitute at least 50%, at least 60%, at least 70%, at least 80%, and/or at least 90% of the fiber blend of the second yarns. In some embodiments, the second yarns include only modacrylic fibers and cellulosic fibers (i.e., the modacrylic and cellulosic fibers collectively constitute 100% of the fiber blend of the second yarns).
In some embodiments, the fiber blend of the overall fabric includes less than approximately 20 wt. % thermally stable fibers (e.g., aramid fibers), less than approximately 15 wt. % thermally stable fibers (e.g., aramid fibers), less than approximately 10 wt. % thermally stable fibers (e.g., aramid fibers), and/or less than approximately 5 wt. % thermally stable fibers (e.g., aramid fibers). In some embodiments, the fiber blend of the overall fabric includes approximately or about (i) 1-25 wt. % thermally stable fibers, inclusive; (ii) 5-20 wt. % thermally stable fibers, inclusive; (iii) 5-15 wt. % thermally stable fibers, inclusive; (iv) 5-10 wt. % thermally stable fibers, inclusive; (v) 10-20 wt. % thermally stable fibers, inclusive; (vi) 10-15 wt. % thermally stable fibers, inclusive; (vii) 2-10 wt. % thermally stable fibers, inclusive; and (viii) 2-8 wt. % thermally stable fibers, inclusive. Again, such fibers are provided in only one fabric direction.
It may be beneficial, but not required, to include nylon fibers or polyester fibers in either or both of the first yarns and the second yarns to impart strength and abrasion resistance and thus enhance the durability and wear properties of the fabric made with such yarns.
It has also been discovered that incorporating into the fabric (via the first yarns, second yarns, or otherwise) fibers having at least one energy absorbing and/or reflecting additive may be beneficial. It is believed that such energy (e.g., radiation) absorbing and/or reflecting additives serve to prevent heat energy transmission through the fabric and to the wearer's skin by absorbing the energy and/or reflecting the energy away from the fabric such that it does not reach the wearer. Additive-containing fibers (“AC fibers”) are fibers whereby an energy absorbing and/or reflecting additive is introduced during the process of manufacturing the fibers themselves and not after fiber formation. This is in contrast to a finish applied onto the fabric surface whereby a binder typically must be used to fix the additive onto the fabric. In these cases, the additive is apt to wash and/or wear/abrade off the fabric during laundering. Provision of the additive in the fibers during fiber formation results in better durability as the additive is trapped within the fiber structure. Examples of AC fibers are identified and described in U.S. Patent Publication No. 2017/0370032 to Stanhope et al., U.S. Patent Publication No. 2017/0295875 to Ohzeki et al., and U.S. patent Ser. No. 16/271,162 to Stanhope et al., the entirety of each of which is herein incorporated by reference. Some AC fibers are producer-colored fibers. In producer coloring (also known as “solution dyeing”), pigment is injected into the polymer solution prior to forming the fibers. Thus, “producer-colored” (i.e., “PC”) fibers refers to fibers that are colored during the process of manufacturing the fibers themselves and not after fiber formation.
Note that while AC fibers may be used in embodiments of the fabrics contemplated herein, they need not be used. If AC fibers are desired, the AC fibers may be incorporated into either or both of the first and second yarns. In some embodiments, at least some of the thermally stable fibers of the first yarns are AC fibers. In some embodiments, the AC fibers are only incorporated into the fiber blend of the first yarns and are not incorporated into the second yarns. In some embodiments, the aramid fibers in the first yarns are AC fibers.
The first and second yarns can comprise a single yarn or two or more individual yarns that are combined together in some form, including, but not limited to, twisting, plying, tacking, wrapping, covering, core-spinning (i.e., a filament or spun core at least partially surrounded by spun fibers or yarns), etc.
In some embodiments, the first and second yarns are woven or knitted to form a woven or knitted fabric. In some embodiments, the fabrics are woven fabrics formed of the first yarns and the second yarns. The first yarns (those having thermally stable fibers) are provided in a first fabric direction (the warp or weft direction). The second yarns (those devoid of thermally stable fibers) are provided in a second fabric direction (the other of the warp or weft direction). In some embodiments, the second yarns may also be provided in the first fabric direction but the first yarns are only provided in the first fabric direction. In this way, yarns with thermally stable fibers are only provided in one direction of the fabric (i.e., are not provided in the second fabric direction).
It will also be recognized that any woven or knitted fabric will have both warp and fill yarns visible on each side of the fabric. While more first yarns than second yarns (or vice versa) may be exposed on each side of the fabric depending on the thread-up, the fabric may be constructed such that approximately the same amount of first yarns and the same amount of second yarns are exposed on each side of the fabric (i.e., if the first yarns are exposed on 35% of one side of the fabric, they will be exposed on 35% of the other side of the fabric). This can be achieved, for example, with a plain weave construction.
In other embodiments, the fabrics have anisotropic properties in that the fabrics are constructed such that more of the first yarns are located on one side of the fabric (e.g., the body side of the fabric proximate the wearer), and more of the second yarns are located on the opposing side of the fabric (e.g., the face side of the fabric facing away from the wearer). An anisotropic construction can be achieved in a variety of ways, including but not limited to, one or more of a twill weave (2×1, 3×1, etc.), twill weave containing a rip-stop pattern, satin weave (4×1, 5×1, etc.), sateen weave, and double-cloth constructions, or any other weave where yarn is predominantly more on one side of the fabric than the other side of the fabric. In other embodiments of the invention, a knit fabric that has different properties on each side of the fabric can be constructed. Such a fabric could be constructed using double-knit technology such that the first yarns will be predominantly exposed on a first side of the fabric and the second yarns will be predominantly exposed on the opposing second side of the fabric. A person skilled in the art would be familiar with and could utilize suitable fabric constructions.
Some embodiments of the fabric have a weight between 6 to 14 ounces per square yard (osy), inclusive, such as between 8 to 12 osy, inclusive; between 9 to 11 osy, inclusive; and between 9.5, and 11.5 osy, inclusive.
Tables 1-3 set forth testing results of various properties of fabrics not made in accordance with embodiments of the inventive fabrics contemplated herein (Comparative Fabrics (“CF”) 1-4) as well fabrics made in accordance with embodiments of the inventive fabrics contemplated herein (Inventive Fabrics (“IF”) 1-7). Inventive Fabrics 1-7 were finished but without the use of any property-imparting (e.g., flame retardant) additive.
Embodiments of the fabrics disclosed herein comply with the vertical flammability requirements of NFPA 2112 and/or NFPA 1975 (char length of 4 inches or less and/or 6 inches of less and a two second or less afterflame), when measured pursuant to the testing methodology set forth in ASTM D6413. Inventive Fabrics 1-7 also all comply with the thermal shrinkage requirement of NFPA 2112 (no more than 10% thermal shrinkage in each of the warp and weft fabric direction). Of note is that the thermal shrinkage of Inventive Fabrics 1-7 was in line with (and sometimes better than) that of Comparative Fabrics 2-4 which include thermally stable fibers in both directions.
The fabrics described herein can be incorporated into any type of single or multi-layer garment (uniforms, shirts, jackets, trousers and coveralls) where protection against electric arc flash and/or flames is needed and/or desirable. In some embodiments, the fabric is an anisotropic fabric and the fabric is provided within the garment such that the first yarns are predominantly exposed on the body side of the garment (the side facing or proximate the wearer) and the second yarns are predominantly exposed on the face side of the garment (the side facing outwardly from the wearer).
A collection of exemplary embodiments, including at least some explicitly enumerated as “Examples” providing additional description of a variety of example types in accordance with the concepts described herein are provided below. These examples are not meant to be mutually exclusive, exhaustive, or restrictive; and the invention is not limited to these example examples but rather encompasses all possible modifications and variations within the scope of the issued claims and their equivalents.
Example 1. A flame resistant fabric having a first side and a second side opposite the first side, wherein the fabric is formed of a plurality of yarns oriented in a first fabric direction and in a second fabric direction opposite the first fabric direction, wherein the plurality of yarns comprises first yarns and second yarns and wherein the first yarns comprise a first fiber blend comprising thermally stable fibers, cellulosic fibers, and modacrylic fibers, wherein the thermally stable fibers constitute less than 25 wt. % of the first fiber blend; the modacrylic fibers and the cellulosic fibers of the first fiber blend collectively constitute at least 60 wt. % of the first fiber blend; the first fiber blend comprises more modacrylic fibers than thermally stable fibers; the first fiber blend comprises more cellulosic fibers than thermally stable fibers; the second yarns comprise a second fiber blend that is different from the first fiber blend and that comprises modacrylic fibers and cellulosic fibers, wherein the second fiber blend is devoid of thermally stable fibers; the first yarns are provided only in the first fabric direction and not in the second fabric direction; the second yarns are provided in the second fabric direction; the fabric has a fabric weight between 8 to 12 ounces per square yard, inclusive; the fabric has a char length of 6 inches or less and an after flame of 2 seconds or less when tested pursuant to ASTM D6413 (2022); and the fabric exhibits thermal shrinkage of no more than 10% in each of the first fabric direction and the second fabric direction in accordance with NFPA 2112 (2023).
Example 2. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the modacrylic fibers and the cellulosic fibers of the first fiber blend collectively constitute at least 70 wt. % of the first fiber blend.
Example 3. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the modacrylic fibers and the cellulosic fibers of the first fiber blend collectively constitute at least 80 wt. % of the first fiber blend.
Example 4. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the thermally stable fibers comprise aramid fibers.
Example 5. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the thermally stable fibers constitute less than 20 wt. % of the first fiber blend.
Example 6. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the modacrylic fibers and the cellulosic fibers of the second fiber blend collectively constitute at least 60 wt. % of the second fiber blend.
Example 7. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the modacrylic fibers and the cellulosic fibers of the second fiber blend constitute at least 70 wt. % of the second fiber blend.
Example 8. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the modacrylic fibers and the cellulosic fibers of the second fiber blend constitute at least 80 wt. % of the second fiber blend.
Example 9. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the modacrylic fibers and the cellulosic fibers of the second fiber blend constitute at least 90 wt. % of the second fiber blend.
Example 10. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the second fiber blend consists of the modacrylic fibers and the cellulosic fibers.
Example 11. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the first fiber blend comprises about 8-20 wt. % thermally stable fibers, about 40-55 wt. % modacrylic fibers, and about 30-45 wt. % cellulosic fibers.
Example 12. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the thermally stable fibers comprise aramid fibers.
Example 13. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the second fiber blend comprises about 40-60 wt. % modacrylic fibers and about 40-60 wt. % cellulosic fibers.
Example 14. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the fabric has an overall fabric fiber blend and wherien the thermally stable fibers comprise less than about 10% of the overall fabric fiber blend.
Example 15. The fabric of any of the preceding or subsequent examples or combination of examples, wherein the first yarns are predominantly exposed on the first side of the fabric and the second yarns are predominantly exposed on the second side of the fabric.
Example 16. The fabric of any of the preceding or subsequent examples or combination of examples, wherein at least some of the cellulosic fibers in the first fiber blend are non-flame resistant.
Example 17. The fabric of any of the preceding or subsequent examples or combination of examples, wherein at least some of the cellulosic fibers in the second fiber blend are non-flame resistant.
Example 18. A garment formed with the fabric of any of the preceding or subsequent examples or combination of examples, the fabric having a face side and a body side.
Example 19. The garment of Example 18, wherein the first yarns of the fabric are predominantly exposed on the first side of the fabric, the second yarns of the fabric are predominantly exposed on the second side of the fabric, the first side of the fabric is exposed on the body side of the garment, and the second side of the fabric is exposed on the face side of the garment.
Example 20. A flame resistant fabric having a first side and a second side opposite the first side, wherein the fabric is formed of a plurality of yarns oriented in a first fabric direction and in a second fabric direction opposite the first fabric direction, wherein the plurality of yarns comprises first yarns and second yarns and wherein the first yarns comprise a first fiber blend comprising about 8-20 wt. % thermally stable fibers, about 40-55 wt. % modacrylic fibers, and about 30-45 wt. % cellulosic fibers, wherein the thermally stable fibers comprise aramid fibers; the modacrylic fibers and the cellulosic fibers of the first fiber blend collectively constitute at least 70 wt. % of the first fiber blend; the first fiber blend comprises more modacrylic fibers than cellulosic fibers; the second yarns comprise a second fiber blend that is different from the first fiber blend and that comprises about 40-60 wt. % modacrylic fibers and about 40-60 wt. % cellulosic fibers, wherein the second fiber blend is devoid of thermally stable fibers; the first yarns are provided only in the first fabric direction and not in the second fabric direction; the second yarns are provided in the second fabric direction; the fabric has a fabric weight between 8 to 12 ounces per square yard, inclusive; the fabric has a char length of 6 inches or less and an after flame of 2 seconds or less when tested pursuant to ASTM D6413 (2022); and the fabric exhibits thermal shrinkage of no more than 10% in each of the first fabric direction and the second fabric direction in accordance with NFPA 2112 (2023).
Different arrangements of the components described above, as well as components and steps not shown or described are possible. Similarly, some features and subcombinations are useful and may be employed without reference to other features and subcombinations. Embodiments of the invention have been described for illustrative and not restrictive purposes, and alternative embodiments will become apparent to readers of this patent. Accordingly, the present invention is not limited to the embodiments described above or depicted in the drawings, and various embodiments and modifications can be made without departing from the scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 63/335,255, filed Apr. 27, 2022 and entitled “Thermally Stable Inherently Flame-Resistant Textile Produced from Thermally Stable Yarn in Only One Direction,” the entirety of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63335255 | Apr 2022 | US |
