WO2016114984A1

WO2016114984A1 - Flame resistant fabric

Info

Publication number: WO2016114984A1
Application number: PCT/US2016/012586
Authority: WO
Inventors: Chuanpu GUO; Todd C. Barnes; David Anthony GREEN
Original assignee: Invista North America S.Ar.L.
Priority date: 2015-01-12
Filing date: 2016-01-08
Publication date: 2016-07-21
Also published as: RU2705605C2; BR112017014915A2; RU2017128454A; MX2017009135A; KR20170104539A; EP3245320B1; CN107567510A; EP3245320A1; RU2017128454A3; IL253404A0; US20180274136A1; JP2018502230A

Abstract

Flame resistant fabrics made from yarns of cellulose fiber, polyamide fiber, and oxidized polymeric biregional fiber are provided. The fabrics comprise about 20 to about 90 percent by weight of cellulose fiber, about 3 to about 45 percent by weight of polyamide fiber and about 5 to about 35 percent by weight of an oxidized polymeric biregional fiber comprising an oxidized polymer selected from the group consisting of acrylonitrile-based homopolymers, acrylonitrile- based copolymers, acrylonitrile-based terpolymers, and combinations thereof.

Description

FLAME RESISTANT FABRIC

Field of Invention

[0001] The present disclosure relates to flame resistant fabrics made from yarns comprising cellulose fiber, polyamide fiber, and oxidized polymeric biregional fiber.

Background

[0002] Flame resistant garments are worn by workers exposed to thermal and flame hazards in the workplace such as heat, open flame, and electric arc flash to reduce potential bodily injuries.

[0003] Many flame resistant garments are made with 88/12 fabrics comprising a blend of 88% cotton fibers and 12% nylon fibers. The fabrics are typically heated with phosphorous-based flame retardant chemicals. The fabrics meet the industrial standards of flammability performance requirements. Further, because the majority of the fabric comprises cotton fibers, the fabrics are relatively inexpensive. In addition, these fabrics are more durable during industrial laundering and wearing as compared to 100% cotton fabrics since addition of nylon fibers to the fabric provides a significant improvement in abrasion resistance of the fabrics. The 88/12 fabrics are commercially available at a weight of approximately 6.5-7.0 oz/yd² or more. One example of an 88/12 fabric is UltraSoft® fabric produced by Westex Inc, an entity of Miliken and Co.

[0004] There has been a continuing need from end-users, however, for inexpensive, flame retardant fabrics weighing less than 6.5 oz/yd² that are still durable for industrial laundering and wearing. Currently, 88/12 fabrics at a weight less than 6.5 oz/yd² exhibit deficiencies in meeting industrial flammability standards.

[0005] In order to meet these standards, inherently flame resistant fibers such as meta-aramid fibers, commercially marketed as Nomex® fibers by Dupont Company, are used for light weight flame retardant fabrics.

[0006] U.S. Patent 6,358,608 discloses fire retardant and heat resistant yarns, fabrics, felts and other fibrous blends which incorporate up to 99.9% oxidized polyacrylonitrile fibers together with at least additional fiber such as p-aramid.

[00071 Published U.S. Patent Application No. 2011/0165397 discloses stitch bonded flame resistant fabrics comprising partially oxidized polyacrylonitrile fibers and/or yarns. [0008] Published U.S. Patent Application No. 2011/0239618 discloses a fire retardant fabric manufactured from oxidized polyacrylonitrile fibers having a fineness of about 0.5 to about 1.5 denier per fiber.

[0009] Published U.S. Patent Application No. 2014/0047625 discloses clothing and fabric made from oxidized polyacrylonitrile or other high limiting oxygen index materials in which the yarn strands are encapsulated or coated with a water shedding silicone polymer or other water- shedding material.

[0010] However, the fabrics described in the above-mentioned references are expensive, and are uncomfortable to wear.

[0011] WO 2010/135214 discloses flame resistant fabrics made from a blend of lyocell fibers and flame resistant fibers such as flame resistant (FR) cotton and FR treated rayon.

[0012] WO 2011/050257 discloses a blended yarn and fabric comprising from 10% to 85% by weight of an oxidized polymeric biregional fiber, such as an oxidized polyacrylonitrile fiber. The disclosed yarn is blended with at least one synthetic fiber from the group consisting of FR rayon, FR treated cellulose, m-aramid,p-aramid, modacrylic, novoloid, melamine, wool, nylon, regenerated cellulose, polyvinyl chloride, antistatic fiber, poly(p-phenylenebenzobisoxazole) (PBO), polybenzimidazole (PBI), and polysulphonamide (PSA).

[0013] Thus, there is a need for lightweight flame resistant fabrics that are durable for industrial laundering, comfortable for wearing, affordable for end users, and in compliance with industrial standards such as are described in NFPA 70E ("Standard for Electrical Safety in the Workplace") and NFPA 2112 ("Standard on Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire").

Summary of the Invention

[0014] An aspect of the present invention relates to a fabric comprising about 20 to about 90 percent by weight of cellulose fiber; about 3 to about 45 percent by weight of polyamide fiber; and about 5 to about 35 percent by weight of biregional fiber comprising an oxidized polymer selected from the group consisting of acrylonitrile-based homopolymers, acrylonitrile-based copolymers, acrylonitrile-based terpolymers, and combinations thereof.

[0015] In one nonlimiting embodiment, the fabric has a basis weight of from about 3.0 oz/yd² to about 15 oz/yd² . [0016] In one nonlimiting embodiment, the fabric is treated with flame retardant chemistry.

[0017] In one nonlimiting embodiment, the fabric has an arc thermal performance value of about 8 cal/cm² or greater.

[0018] In one nonlimiting embodiment, the fabric has a ratio of arc thermal performance value to basis weight of about 1.24 or greater.

[0019] In one nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise the biregional fibers.

[0020] Another aspect of the current invention relates to a fabric comprising about 20 to about 90 percent by weight of cellulose fiber, about 3 to about 45 percent by weight of polyamide fiber, about 1 to about 9 percent by weight of para-aramid fiber, about 1 to about 20 percent by weight of FR rayon fiber and about 5 to about 35 percent by weight of biregional fiber comprising an oxidized polymer selected from the group consisting of acrylonitrile-based homopolymers, acrylonitrile-based copolymers, acrylonitrile-based terpolymers, and

combinations thereof, wherein the fabric has a basis weight of from about 3.0 oz/yd² to about 15 oz/yd², and wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise the majority of the FR rayon, para-aramid and the biregional fibers.

Detailed Description of the Invention

[0021] Provided by this disclosure are light-weight, inexpensive, flame resistant fabrics made from yarns comprising fiber from about 20% to about 90% by weight of cellulose fiber, about 3% to about 45% by weight of polyamide fiber, and about 5% to about 35% by weight of oxidized polymeric biregional fiber. All numerical values recited herein are understood to be modified by the term "about".

[0022] Sufficient cellulose fibers from about 20% to about 90% by weight are used in these fabrics to improve the comfort properties of fabric and reduce material cost. Cellulose fiber refers to cotton fibers, other natural cellulose fibers and synthetic cellulosic fibers. Synthetic cellulosic fibers include, but are not limited to rayon and lyocell. In some preferred

embodiments the cellulose fiber is cotton fiber. Additional examples of cellulose fibers useful in these fabrics include, but are not limited to, linen, hemp, bamboo, rayon and jute.

[0023] Polyamide fibers from about 3% to about 45% by weight are included in the yarns to impart a durability to the fabrics similar to, or better than, 88/12 fabrics. Suitable polyamides include, but are not limited to, nylon 6,6; nylon 6; nylon 4,6; nylon 6,12; nylon 6,10; nylon 6T; nylon 6I; nylon 9T; nylon DT (where D = Dytek® A diamine, 2-methyl-1,5-diaminopentane); nylon DI; nylon D6; nylon 7; nylon 11; nylon 12; nylon MXD-6 and/or combinations thereof. By "combinations thereof with respect to polyamides, it is meant to include, but is not limited to, block copolymers, random copolymers, terpolymers, as well as melt blends. In some preferred embodiments the polyamide fiber is nylon 6,6 fiber.

[0024] Fabrics of this disclosure further comprise about 5% to about 35% by weight of oxidized polymeric biregional fiber. The oxidized polymeric biregional fiber includes the oxidized fibers formed from rayon based fibers, pitch based fibers and fibers formed from polymers selected from the group comprising acrylonitrile-based homopolymers, acrylonitrile-based copolymers, acrylonitrile-based terpolymers and combinations thereof. In some nonlimiting embodiments an oxidized polyacrylonitrile fiber is used. Examples of oxidized polymeric biregional fibers useful in these fabrics are set forth in WO 2011/050257 A2, teachings of which are incorporated herein by reference. In one embodiment, inherent flame resistant oxidized polyacrylonitrile fibers from about 5% to about 35% by weight are used as the oxidized polymeric biregional fiber to provide these fabrics with superior heat, flame, and electric arc flash protection performance.

[0025] Fabrics containing the disclosed blend of fibers are durable, comfortable, inexpensive, and flame resistant.

[0026] In one nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise the biregional fibers. The inventors have discovered that it is advantageous to ensure that a majority of polyamide fibers are in the warp yarns so that they are distributed on the surface size of twill or sateen fabrics, while a majority of the biregional fibers are in the filling direction so that they are on the back side of the fabrics. This is because the biregional fibers may not be dyeable and can remain hidden, which improves the durability, appearance and applicability of the fabric.

[0027] In one nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise about 50 to about 100 percent by weight of the biregional fibers in the fabric.

[0028] In another nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise at least about 75 percent by weight of the biregional fibers in the fabric. [0029] In yet another nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise about 100 percent by weight of the biregional fibers in the fabric.

[0030] In one nonlimiting embodiment, the fabric further comprises from about 1 to about 9 percent by weight of para-aramid fiber. In another nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 50 to about 100 percent by weight of the para-aramid and the biregional fibers. In yet another nonlimiting embodiment, the fabric comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 100 percent by weight of the para-aramid fibers and the biregional fibers.

[0031] In one nonlimiting embodiment, the fabric further comprises from about 1 to about 20 percent by weight of FR rayon fiber. In another nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 50 to about 100 percent by weight of the FR rayon fibers and the biregional fibers. In yet another nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 100 percent by weight of the FR rayon fibers and the biregional fibers.

[0032] In one nonlimiting embodiment, the fabric further comprises fr om about 1 to about 9 percent by weight of para-aramid fiber and from about 1 to about 20 percent by weight of FR rayon fiber. In another nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 50 to about 100 percent by weight of the FR rayon fibers, the para-aramid fibers and the biregional fibers. In yet another nonlimiting embodiment, the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 100 percent by weight of the FR rayon fibers, the para-aramid fibers and the biregional fibers.

[0033] Further, fabrics made in accordance with this disclosure are light weight and durable for the industrial laundering and wearing. In one embodiment, the weight of the fabric is from about 3.0 oz/yd² to about 15 oz/yd². In one embodiment, the weight of the fabric is less than about 6.5 oz/yd², for example, from about 3 oz/yd² to about 6.5 oz/yd².

[0034] Another aspect of the current invention relates to a fabric comprising about 20 to about 90 percent by weight of cellulose fiber, about 3 to about 45 percent by weight of polyamide fiber, about 1 to about 9 percent by weight of para-aramid fiber, about 1 to about 20 percent by weight of FR rayon fiber and about 5 to about 35 percent by weight of biregional fiber comprising an oxidized polymer selected from the group consisting of acrylonitrile-based homopolymers, acrylonitrile-based copolymers, acrylonitrile-based terpolymers, and

[0035] In nonlimiting embodiment of this aspect, the filling yarns comprise from about 100 percent by weight of the FR rayon fibers, the para-atamid fibers and the biregional fibers.

[0036] Fabrics produced in accordance with this disclosure include, but are not limited to, knitted, woven, and nonwoven fabrics having the fiber blend disclosed herein and can be used to make various flame resistant garments for heat, flame, electric arc flash protection applications. The woven construction may include, but is not limited to, plain, basket, twill, satin or sateen weave as well as a more durable ripstop weave. In some embodiments, the fabrics can be formed with yarns produced by the various types of spinning technologies such as, but not limited to, ring spinning, open-end (OE), air jet, Vortex, core spun, and others.

[0037] The fabrics, in some embodiments, can be dyed by commercially available dye methods.

[0038] Further, in some embodiments, fabrics produced in accordance with this disclosure are treated with phosphorous-based flame retardant chemicals and/or other flame retardant chemicals. In one nonlimiting embodiment, the fabric is treated by phosphorous-based flame retardant chemicals in the presence of urea/ammonia.

[0039] These fabrics provide superior flame and thermal protection performance for flame resistant applications in accordance with the industrial standard test methods. The fabrics, in some embodiments at a light weight of about 6.5 oz/yd² or even lower such as less than 6.0 oz/yd², have an arc rating of about 8.0 or greater, which meets or exceeds the performance requirement in arc rating according to ASTM F1959, "Standard Test Method for Determining the Arc Rating of Materials for Clothing." The fabrics at about 6.5 oz/yd² have a ratio of arc rating (Arc thermal performance value) to fabric weight of about 1.24 or higher, while the fabrics at a weight less than about 6.0 oz/yd² have a ratio of arc rating (Arc thermal performance value) to fabric weight of about 1.36 or higher. Fabrics with high ratio of arc rating to fabric weight of about 1.24 to about 1.36 or even greater provide wearers of garments a comfortable protective garment with superior electric arc flash protection performance. The fabrics of some embodiments at light weight of about 6.5 oz/yd² or even lower such as less than about 6.0 oz/yd² meet or exceed performance requirements for flash fire protection applications in accordance with National Fire Protection Association Standard (NFPA) 2112 (2012), "Standard on Flame- Resistance Garments for Protection of Industrial Personnel Against Flash Fire." Further, the light weight fabrics of this disclosure have been demonstrated to have a char length less than 4 inches in a vertical flammability test according to the ASTM D6413: Standard Test Method for Flame Resistance of Textiles (Vertical Test). In addition, the fabrics of this disclosure were

demonstrated to have a heat transfer performance (HTP) rating greater than 8.0 cal/cm² per the NFPA 2112: (National Fire Protection Association) Standard on Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire. Section 8.2 (Heat Transfer Performance) and an average predicted body burn less than 50 percent per the ASTM F1930: Standard Test Method for Evaluation of Flame Resistant Clothing for Protection Against Fire Simulations Using an Instrumented Manikin. Thus, the light weight fabrics of this disclosure fabrics meet both the performance requirements on the electric arc rating for HRC level II in NFPA standard 70 E (2012) and the performance requirements on the flash fire protection in the NFPA 2112 (2012) standard. Further, some embodiments of these light weight fabrics can be dual certified fabrics for both the NFPA 70E HRC level II and NFPA 2112 (2012).

[0040] Also disclosed are articles formed from fabrics of the current disclosure. In some embodiments, the articles include, but are not limited to apparel, shirts, pants, jackets and coveralls.

[0041] The following section provides further illustration of the fabrics of this invention. These working examples are illustrative only and are not intended to limit the scope of the invention in any way.

EXAMPLES

Example 1: Fabrics and Yarn Samples

[0042] Table 1 lists multiple fabric and yarn samples. Fabric sample 1 is an embodiment of the current invention. Fabric samples 2 and 3 are comparative examples. All three fabric samples were woven fabrics having a twill construction. Fabric sample 1 was woven with yarns comprising 47 weight % cellulose fiber, 14 weight % FR rayon fiber, 16 weight % polyamide fiber, 6 weight % para-aramid fiber, and 17 weight % oxidized polymeric biregional fiber. Fabric sample 1 comprised warp yarns comprising the cellulosic fibers and the polyamide fibers, and filling yarns comprising the FR rayon fibers, the polyamide fibers, the para-aramid fibers and the biregional fibers. In this way, a large portion of polyamide fibers were distributed on the surface size of twill fabrics, while many oxidized biregional polyacrylonitrile fibers and para- aramid fibers that were not dyeable were hidden on the back side of twill fabrics. As a result, durability and appearance of the fabrics was substantially improved.

[0043] Fabric sample 2 is a baseline fabric for comparison with fabric sample 1. Fabric sample 2 was woven with the same filling yarns, but different warp yarns when compared to fabric sample 1. Fabric sample 2 comprised 35 weight % FR rayon fiber, 2 weight % polyamide fiber, 15 weight % para-aramid fiber, 29 weight % modacrylic fiber and 19 weight % oxidized polymeric biregional fiber.

[0044] Fabric sample 3 is another baseline fabric for comparison with fabric sample 1. Fabric sample 3 was woven with the same warp yarns and different filling yarns when compared to fabric sample 1. Fabric sample 3 comprised 88 weight % cotton fiber and 12 weight % polyamide fiber.

[0045] Table 1. Fabrics and Yarns

Example 2

Test Methods

[0046] Test methods used to evaluate fabrics of the present invention included:

[004η ASTM D6413: Standard Test Method for Flame Resistance of Textiles (Vertical Test);

[0048] NFPA 2112 (2012): (National Fire Protection Association) Standard on Flame-Resistant,

Garments for Protection of Industrial Personnel Against Flash Fire. Section 8.2 (Heat Transfer

Performance);

[0049] NFPA 2112 (2012): (National Fire Protection Association) Standard on Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire. Section 8.4 (Thermal Shrinkage Resistance);

[0050] ASTM F1930: Standard Test Method for Evaluation of Flame Resistant Clothing for Protection Against Fire Simulations Using an Instrumented Manikin;

[0051] ASTM F1959: Standard Test Method for Determining the Arc Rating of Materials for Clothing; and

[0052] NFPA 70E (2012): Standard for Electrical Safety in the Workplace

[0053] The term HTP, as used herein, refers to Heat Transfer Performance.

[0054] The term ATPV, as used herein, refers to Arc Thermal Performance value.

[0055] Table 2 lists test results for fabric samples of Example 1.

[0056] Table 2 Test Results, NFPA 70E and NFPA 2112

[0057] All the fabric samples met or exceeded performance requirements for the intended end use applications in accordance with NFPA 70E and NFPA 2112.

[0058] Fabric sample 1 was woven with the same filling yarns and different warp yarns with fabric sample 2. Fabric sample 1 was made with more cellulose fibers, including additional cotton fibers and less para-aramid fibers than fabric sample 2. The ratio of ATPV to fabric weight of fabric sample 1 (1.72) was much higher than that determined for fabric sample 2 (1.21). Fabric sample 1 is woven with the same warp yarns and different filling yarns with fabric sample 3. About 17% by weight oxidized biregional polyacrylonitrile fibers were included in fabric sample 1, which resulted in the higher ratio of ATPV to fabric weight of fabric sample 1 (1.72) than was determined for fabric sample 3 (1.23). The fiber blend used for fabric sample 1 makes it possible to make a light weight cotton/nylon/ oxidized bioregional polyacrylonitrile blend fabric treated by flame retardant chemicals that meet the performance requirements on the electric arc rating for HRC level II in NFPA standard 70 E (2012).

Claims

What is claimed is:

1. Fabric comprising:

a) about 20 to about 90 percent by weight of cellulose fiber;

b) about 3 to about 45 percent by weight of polyamide fiber; and

c) about 5 to about 35 percent by weight of an oxidized polymeric biregional fiber comprising an oxidized polymer selected from the group consisting of acrylonitrile-based homopolymers, acrylonitrile-based copolymers, acrylonitrile-based terpolymers, and

combinations thereof.

2. The fabric of claim 1 wherein the polyamide fiber comprises nylon 6,6.

3. The fabric of claim 1 wherein the oxidized polymeric biregional fiber comprises oxidized polyacrylonitrile fiber.

4. The fabric of claim 1 wherein the fabric has a basis weight of from about 3.0 oz/yd² to about 15 oz/yd².

5. The fabric of claim 1 wherein the fabric has a basis weight of about 3.0 oz/yd² to about 6.5 oz/yd².

6. The fabric of claim 1 wherein the fabric is treated with flame retardant chemistry.

7. The fabric of claim 6 wherein the fabric has an arc thermal performance value of about 8 cal/cm² or greater.

8. The fabric of claim 6 wherein the fabric has a ratio of arc thermal performance value to basis weight of about 1.24 or greater.

9. The fabric of claim 1, wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise the biregional fibers.

10. The fabric of claim 1, wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise about 50 to about 100 percent by weight of the biregional fibers in the fabric.

11. The fabric of claim 1 , wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise at least about 75 percent by weight of the biregional fibers in the fabric.

12. The fabric of claim 1 , wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise about 100 percent by weight of the biregional fibers in the fabric.

13. The fabric of claim 1 further comprising from about 1 to about 9 percent by weight of para-aramid fiber.

14. The fabric of claim 13 wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 50 to about 100 percent by weight of the para-aramid and the biregional fibers.

15. The fabric of claim 13 wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 100 percent by weight of the para- aramid fibers and the biregional fibers.

16. The fabric of claim 1 further comprising from about 1 to about 20 percent by weight of FR rayon fiber.

17. The fabric of claim 15 wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 50 to about 100 percent by weight of the FR rayon fibers and the biregional fibers.

18. The fabric of claim 15 wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 100 percent by weight of the FR rayon fibers and the biregional fibers.

19. The fabric of claim 1 further comprising from about 1 to about 9 percent by weight of para-aramid fiber and from about 1 to about 20 percent by weight of FR rayon fiber.

20. The fabric of claim 19 wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 50 to about 100 percent by weight of the FR rayon fibers, the para-aramid fibers and the biregional fibers.

21. The fabric of claim 19 wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise from about 100 percent by weight of the FR rayon fibers, the para-aramid fibers and the biregional fibers.

22. Fabric comprising:

a) about 20 to about 90 percent by weight of cellulose fiber;

b) about 3 to about 45 percent by weight of polyamide fiber;

c) about 1 to about 9 percent by weight of para-aramid fiber;

d) about 1 to about 20 percent by weight of FR rayon fiber; and

e) about 5 to about 35 percent by weight of biregional fiber comprising an oxidized polymer selected from the group consisting of acrylonitrile-based homopolymers, acrylonitrile- based copolymers, acrylonitrile-based terpolymers, and combinations thereof,

wherein the fabric has a basis weight of from about 3.0 oz/yd² to about 15 oz/yd², and wherein the fabric is woven and comprises warp yarns and filling yarns, wherein the filling yarns comprise the majority of the FR rayon, para-atamid and the biregional fibers.

23. The fabric of claim 22 wherein the polyamide fiber comprises nylon 6,6.

24. The fabric of claim 22 wherein the oxidized polymeric biregional fiber comprises oxidized polyacrylonitrile fiber.

25. The fabric of claim 22 wherein the fabric has a basis weight of about 3.0 oz/yd² to about 6.5 oz/yd².

26. The fabric of claim 22 wherein the filling yarns comprise from about 100 percent by weight of the FR rayon fibers, the para-aramid fibers and the biregional fibers.

27. The fabric of claim 22 wherein the fabric is treated with flame retardant chemistry.

28. The fabric of claim 27 wherein the fabric has an arc thermal performance value of about 8 cal/cm² or greater.

29. The fabric of claim 27 wherein the fabric has a ratio of arc thermal performance value to basis weight of about 1.24 or greater.