Fire-resistant composite sheet

Abstract

The composite sheet comprises a textile component having a first surface and a second surface, and a first polymer coating on the first surface of the textile component, wherein the textile component further comprises at least one woven fabric of continuous filament yarns having an areal weight of from about 70 to about 508 gsm, and a nonwoven fabric comprising a blend of discontinuous fibers of oxidized polyacrylonitrile fibers and silica fibers, wherein the oxidized polyacrylonitrile fibers are present in an amount of from about 30 to about 70 weight percent of the combined weight of the oxidized polyacrylonitrile fibers and the silica fibers, and the nonwoven fabric may be mechanically attached to the woven fabric.

Description

[Technical Field]

[0001] The disclosed embodiments relate generally to fire-resistant composite sheets that are useful as curtain walls for fire-resistant cargo containers, particularly those used in aircraft. [Background technology]

[0002] The amount of cargo carried by both passenger and cargo aircraft has increased over the years. This has raised concerns about the risk of fire within cargo containers due to the increasing amount of power sources, such as high-density energy storage devices or other battery types, within cargo. Below are five recent developments in fire-resistant composite sheets for cargo container walls.

[0003] U.S. Pat. No. 9,296,555 to Kawka and Chang relates to a non-rigid composite sheet comprising, in order: (i) a first component having an areal density of 88 to 678 gsm, the first component including a first fabric of filament yarns having a tensile strength of at least 11 g / dtex and a UV-opaque and all-weather first polymer layer; (ii) a second component having an areal density of 30 to 237 gsm, the second component including a fire-resistant substrate and an inorganic heat-resistant layer; and (iii) a third component having an areal density of 88 to 678 gsm, the third component including a second fabric of filament yarns having a tensile strength of at least 11 g / dtex and a second impact- and mar-resistant polymer layer, the second fabric of the third component being adjacent to the heat-resistant layer of the second component.

[0004] U.S. Pat. No. 9,302,845 to Kawka and Chang discloses a non-rigid composite sheet comprising, in order, a first component having an areal density of 102 to 678 gsm, the first component including a first fabric of filament yarns having a tensile strength of at least 11 g / dtex and a UV-opaque and all-weather first polymer layer; a second component having an areal density of 10 to 170 gsm, the second component including a fire-resistant inorganic heat-resistant layer adjacent to at least one protective polymer layer; and a third component having an areal density of 102 to 678 gsm, the third component including a second fabric of filament yarns having a tensile strength of at least 11 g / dtex and a second impact- and scratch-resistant polymer layer, the second fabric of the third component adjacent to the heat-resistant layer of the second component.

[0005] Kawka and Perez, in U.S. Pat. No. 10,457,013, teach a non-rigid composite sheet comprising, in order: (i) a first component having an areal weight of 88 to 678 gsm, the first component including a first fabric of filament yarns having a tensile strength of at least 11 g / dtex and a first polymer layer that is UV opaque and weatherproof; (ii) a second component having an areal weight of 120 to 430 gsm, the second component including fire-resistant paper; and (iii) a third component having an areal weight of 88 to 678 gsm, the third component including a second fabric of filament yarns having a tensile strength of at least 11 g / dtex and a second polymer layer that is impact- and mar-resistant, the second fabric of the third component being adjacent to the fire-resistant paper of the second component.

[0006] Kawka, U.S. Pat. No. 9,993,989, describes a non-rigid composite sheet comprising, in order: (i) a first component comprising a first fabric of continuous filament yarn having a tensile strength of at least 11 g / dtex and a first polymer layer; (ii) a second component comprising at least one second fabric of continuous filament glass yarn, the second fabric being adjacent to the first fabric of the first component; and (iii) a third component comprising the second polymer layer.

[0007] Kawka's U.S. Pat. No. 10,300,677, in turn, relates to a non-rigid composite sheet comprising: (i) a first component comprising at least one first fabric of continuous filament yarn having a tensile strength of at least 11 g / dtex and a first polymer layer; (ii) a second component comprising at least one second fabric of continuous filament glass yarn, the at least one second fabric being adjacent to the at least one first fabric of the first component; and (iii) a third component comprising the second polymer layer. Summary of the Invention [Problem to be solved by the invention]

[0008] However, there remains a need and desire for additional fire resistant composite sheets for cargo container walls that provide improved fire protection. Further weight reduction is also desirable. [Means for solving the problem]

[0009] In one aspect, the present disclosure provides a composite sheet 11 comprising a textile component 12 having a first surface 13 and a second surface 14, and a first polymer coating 15 on the first surface 13 of the textile component 12. The textile component 12 further comprises: a fabric structure 16 of at least one woven fabric of continuous filament yarn, the woven fabric having an areal weight of about 70 to about 508 gsm; and a nonwoven fabric structure (17) comprising a blend of discontinuous oxidized polyacrylonitrile fibers and silica fibers, wherein the oxidized polyacrylonitrile fibers are present in an amount of about 30 to about 70 weight percent of the combined weight of the oxidized polyacrylonitrile fibers and silica fibers. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an exploded end view of a composite sheet 11 according to an exemplary embodiment. [Figure 2]FIG. 1 is an end view of textile component 12 showing stitching through fabric structures 16 and 17 of textile component 12 according to an exemplary embodiment. [Figure 3] FIG. 1 is an end view of textile component 12 illustrating filament entanglement between fabric structures 16 and 17 of textile component 12 according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the following detailed description, reference is made to the accompanying drawings, which form a part of this specification and which illustrate exemplary embodiments of the present invention. These embodiments are described in sufficient detail to enable those skilled in the art to make and use the embodiments. It will be understood that structural, logical, or procedural changes may be made to the exemplary embodiments disclosed herein without departing from the spirit or scope of the present invention.

[0012] 1 illustrates an exemplary exploded end view of one embodiment of a composite fire resistant sheet 11, generally at 10. The composite sheet 11 includes a textile component 12 having a first surface 13 and a second surface 14, and a first polymeric coating 15 located on the first surface 13 of the textile component 12. An optional second polymeric coating 19 may be located on the second surface 14 of the textile component 12.

[0013] Textile Components The textile component 12 includes two different fabric structures.

[0014] The fabric structure 16 comprises at least one woven fabric of continuous filament yarns.

[0015] The fabric structure 17 is a nonwoven fabric comprising a blend of discontinuous fibers of oxidized polyacrylonitrile fibers and silica fibers. In some embodiments, the oxidized polyacrylonitrile fibers are present in an amount of about 30 to about 70 weight percent of the combined weight of the oxidized polyacrylonitrile fibers and silica fibers, and in other embodiments, about 40 to about 60 weight percent of the combined weight of the oxidized polyacrylonitrile fibers and silica fibers. In some embodiments, the nonwoven fabric has an areal weight of about 100 to about 170 gsm, in other embodiments, about 100 to about 240 gsm, and in other embodiments, about 100 to 305 gsm. Preferably, the fabric structure 17 comprises only one nonwoven fabric, although two or more nonwoven fabrics can be incorporated into the fabric structure 17.

[0016] The fabric structure 16 of the textile component 12 can be attached to the fabric structure 17 by an attachment means. Suitable attachment means for attaching the fabric structures 16 and 17 together include, but are not limited to, gluing, stitching, or fiber entanglement.

[0017] The adhesion can be achieved by placing an adhesive, preferably an adhesive film, between the fabric structures 16 and 17 and allowing the adhesive to cure, or by impregnating one or both of the fabric structures 16 and 17 with a matrix resin, placing the fabric structure 16 in contact with the fabric structure 17 and allowing the matrix resin to cure.

[0018] FIG. 2 shows an example cross-sectional view of a stitching option in which a stitch 20 passes through two fabric structures 16 and 17 of a textile component 12 .

[0019] Figure 3 shows an example cross-sectional view of a fiber entanglement option, often referred to as needle punching or needling. In this process, fine needle barbs repeatedly penetrate the textile component 12, causing the filaments to reorient and extend in the z-direction, approximately perpendicular to the xy-plane of the textile component 12. This intermingling of filaments 21 between the two fabric structures 16 and 17 improves the flammability resistance of the textile component.

[0020] In some embodiments, some combination of adhesives, stitches, or fiber entanglement may be used as attachment means.

[0021] The textile component 12 should preferably have a fabric-to-fabric bond strength when subjected to a puncture of at least 11 kg / 10 cm when tested according to ASTM D1876-08(2015) - Standard Test Method for Peel Resistance of Adhesives, i.e., there is no delamination between the fabric structures 16 and 17 until a tensile strength of at least 11 kg / 10 cm is achieved.

[0022] In some embodiments, one or more of the fabric structures 16 and 17 of the textile component 12 are impregnated with a matrix resin such that the resin is present in an amount of about 5 weight percent to about 45 weight percent of the combined weight of resin and fiber in each of the one or more impregnated fabric structures, in other embodiments, about 7 weight percent to about 40 weight percent of the combined weight of resin and fiber in each of the one or more impregnated fabric structures, in other embodiments, about 7 weight percent to about 20 weight percent of the combined weight of resin and fiber in each of the one or more impregnated fabric structures, and in other embodiments, about 15 to about 20 weight percent of the combined weight of resin and fiber in each of the one or more impregnated fabric structures. The matrix resin can be a phenolic, a flame-retardant epoxy, or a flame-retardant polyurethane. Bio-based resins, such as bio-based perfluoroalkoxy copolymers, bio-based epoxy vitrimers, bio-based polyetherimides, lignin-based phenolics, bio-based polycarbonates, soybean-based unsaturated polyesters, bio-based benzoxazines, bio-based epoxy resins, and green polyethylenes, can also be used. The resins are cured according to the curing cycle recommended by the supplier. A continuous belt press is one example of equipment where the curing process can be affected.

[0023] In one preferred embodiment, both fabric structures 16 and 17 are impregnated with a matrix resin. In yet another embodiment, both fabric structures 16 and 17 are attached to one another by an attachment means and are impregnated with a matrix resin.

[0024] Embodiments in which at least one fabric structure 16 or 17 of textile component 12 is impregnated with resin provide a composite sheet 11 that is rigid and has limited roll-up capabilities. Embodiments in which textile component 12 is not impregnated with resin provide a composite sheet 11 that is semi-rigid, i.e., flexible, and can be rolled up.

[0025] woven fabric Suitable weave styles for one or more woven fabrics of the fabric structure 16 include plain weave, satin weave, basket weave, gauze weave, or twill weave. One suitable fabric for one or more woven fabrics of the fabric structure 16 is a refined 230 gsm 17x17 pick count plain weave fabric made from 1500 denier Kevlar® 29p-aramid yarn. Alternatively, one or more woven fabrics of the fabric structure 16 can be a plain weave fabric including 555 dtex (500 denier) KM2+p-aramid yarn at a density of 11 ends per cm (28 ends per inch) in both the warp and weft directions. When two or more woven fabrics are present in the fabric structure 16, these woven fabrics can be the same or different in either yarn composition and / or weave style. In some embodiments, one or more woven fabrics of the fabric structure 16 have an areal weight of about 70 to about 508 gsm (2.1 to 15 ounces per square yard), in other embodiments about 101 to about 373 gsm (3 to 11 ounces per square yard), and in other embodiments about 101 to about 170 gsm (3 to 5 ounces per square yard).

[0026] In some embodiments, one or more woven fabrics of the fabric structure 16 are refined or heat washed after weaving. Such processes are well known in the textile industry to remove contaminants such as oils from the weaving process.

[0027] One or more woven fabrics of the fabric structure 16 are made from multifilament yarns having multiple filaments. The yarns may be braided and / or twisted. For purposes herein, the term "filament" is defined as a relatively flexible, macroscopically uniform body having a large ratio of its length to the width of its cross-sectional area perpendicular to its length. Filament cross-sections can be any shape but are typically round or bean-shaped. As used herein, the term "fiber" is used interchangeably with the term "filament," and when referring to pick counts, the term "end" is used interchangeably with the term "yarn."

[0028] The filaments can be of any length. Preferably, the filaments are continuous. Multifilament yarns spun onto bobbins in a package contain multiple continuous filaments. The multifilament yarns can be cut into staple fibers to produce spun staple yarns suitable for use in one or more woven fabrics of the fabric structure 16. The staple fibers can have lengths of about 1.5 to about 5 inches (about 3.8 cm to about 12.7 cm). The staple fibers can be straight (i.e., non-corrugated) or corrugated to have sawtooth-shaped corrugations along their length, with a corrugation (or repeated bending) frequency of about 3.5 to about 18 corrugations / inch (about 1.4 to about 7.1 corrugations / cm).

[0029] In some embodiments, the yarns of one or more woven fabrics of the fabric structure 16 have a yarn tensile strength of at least about 11 grams / dtex and a modulus of at least about 100 grams / dtex. In some embodiments, the yarns of one or more woven fabrics of the fabric structure 16 have a linear density of about 333 to about 2222 dtex (300-2000 denier), in other embodiments about 555 to about 1111 dtex (500-1000 denier), in other embodiments about 555 dtex, and in other embodiments about 1111 dtex.

[0030] The yarn fibers of the textile structure 16 may be polymeric, inorganic, or natural and may be made from any suitable material known in the art. In some embodiments, the yarn fibers may be aromatic polyamides, aromatic copolyamides, aliphatic polyamides, polyolefins, polyazoles, glass, carbon, multicomponent fibers, and combinations thereof.

[0031] When the polymer is a polyamide, aramid is preferred. As used herein, "aramid" refers to a polyamide polymer in which at least 85% of the amide (-CONH-) linkages are directly attached to two aromatic rings. A para-aramid polymer is an aramid polymer in which the amide linkages are para-positioned relative to each other. One preferred para-aramid polymer is poly(paraphenylene terephthalamide) or PPD-T. It has been found that additives can be used with aramid, and in fact, up to 10% by weight of other polymeric materials can be blended with aramid, or copolymers can be used in which the diamine of the aramid is replaced with 10% or the diacid chloride of the aramid is replaced with 10% or the diacid chloride of the aramid is replaced with 10% or the diacid chloride. Suitable aramid fibers are described in "Man-Made Fibers - Science and Technology," Volume 2, Section titled Fiber-Forming Aromatic Polyamides, page 297, W. Black et al., Interscience Publishers, 1968. Aramid fibers and their manufacture are also disclosed in U.S. Pat. Nos. 3,767,756, 4,172,938, 3,869,429, 3,869,430, 3,819,587, 3,673,143, 3,354,127, and 3,094,511.

[0032] Other useful para-aramids include aramid copolymers obtained from the incorporation and / or substitution of other aromatic diamines and other aromatic diacid chlorides, such as 2,6-naphthaloyl chloride or chloro- or dichloroterephthaloyl chloride or 3,4'-diaminodiphenyl ether. Other preferred para-aramids include aramid copolymers derived from 5(6)-amino-2-(p-aminophenyl)benzimidazole (DAPBI), para-phenylenediamine (PPD), and terephthaloyl dichloride (TCl or T, also commonly referred to as terephthaloyl chloride), such as those in U.S. Patent Application Publication No. 2014 / 0357834, Russian Patent Application Publication No. 2,045,586, and other such polymers shown, for example, in Sugak et al., Fiber Chemistry Vol. 31, No. 1, 1999, U.S. Patent No. 4,018,735, WO 2008 / 061668, and U.S. Patent Application Publication No. 2014 / 357834.

[0033] Examples of commercially available para-aramid fibers include Kevlar® from DuPont of Wilmington, Delaware, and Twaron® from Teijin Aramid of Arnhem, Netherlands. Examples of aramid copolymer fibers include Armos® and Rusar® from Kamenskvolokno Company of Kamensk-Shakhtinskii, Russia.

[0034] The glass fibers may include "E" glass and "S" glass. E-glass is a commercially available low-alkali glass. One typical composition consists of 54 wt. % SiO, 14 wt. % AlO, 22 wt. % CaO / MgO, 10 wt. % BO, and less than 2 wt. % NaO / KO. Several other materials may also be present at impurity levels. S-glass is a commercially available magnesia-alumina-silicate glass. This composition is harder and stronger than E-glass and is commonly used in polymer matrix composites. Exemplary woven fabrics for the fabric structure 16 include, but are not limited to, thermally washed woven style 7781 with E-glass yarns and thermally washed woven style 6781 with S-glass yarns.

[0035] Suitable carbon fibers are standard or medium modulus fibers such as those available from Toray Industries under the Torayca trade name or from Hexcel Corporation under the HexTow trade name. Typically, such fibers have 3,000, 6,000, 12,000, or 24,000 filaments per tow.

[0036] In some embodiments, the fabric structure 16 may be optionally treated with a flame-retardant component. Suitable flame-retardant components include, but are not limited to, halogenated flame retardants such as antimony trioxide, tetrabromobisphenol A, polybrominated biphenyls, pentabrominated diphenyl ether (oxide), octabrominated diphenyl ether (oxide), decabrominated diphenyl ether (oxide), and hexabromocyclododecane. Phosphorus-containing flame retardants are also widely used.

[0037] polymer coating The polymer of the first polymer coating 15 or the second polymer coating 19 can be a thermoplastic polymer, a thermoset polymer, or a silicone rubber.

[0038] Suitable polymers include polyurethane, polyethylene, polypropylene, polyethylene naphthalate, polyacrylonitrile, fluoropolymers, polyimides, polyketones, polyimides (Kapton®), polysulfones, polyarene sulfides, liquid crystal polymers, polycarbonates, and ionomers such as ethylene methacrylic acid copolymer (E / MAA).

[0039] Exemplary fluoropolymers include polyvinyl fluoride (Tedlar®), ethylene chlorotrifluoroethylene copolymer (Halar®), and polytetrafluoroethylene (Teflon®). Exemplary polyketones include polyetheretherketone (PEEK) and polyetherketoneketone (PEKK).

[0040] In one embodiment, first polymer coating 15 is polyurethane. In another embodiment, second polymer coating 19 is an ionomer resin, such as ethylene methacrylic acid copolymer. In yet another embodiment, first polymer coating 15 is opaque and impermeable to UV radiation. By opaque and impermeable to UV radiation, it is meant that at least 95%, more preferably at least 98%, and most preferably 100% of UV radiation is blocked, particularly at the high end of the UV spectrum.

[0041] In some embodiments, the areal weight of first polymer coating 15 and / or second polymer coating 19 is from about 17 to about 170 gsm (0.5 to 5 ounces per square yard), in other embodiments from about 34 to about 136 gsm (1 to 4 ounces per square yard), and in other embodiments from about 67 to about 102 gsm (2 to 3 ounces per square yard).

[0042] Preferably, the first and second polymer coatings 15 and 19 may each be polyurethane, silicone rubber, polyvinyl chloride, or blends thereof. In some embodiments, the second polymer coating 19 may be an ionomer resin based on an ethylene acid copolymer, such as Surlyn®.

[0043] A first polymeric coating 15 contacts the first surface 13 of the textile component 12 and provides chemical and environmental (ie, weather and UV) resistance to both physical and chemical attack and penetration by liquids.

[0044] Chemical and environmental / weather resistance refers to the ability of the polymer coating to withstand, without undue degradation, the effects of wind, rain, contaminants such as acidic and / or oily residues found in typical industrial areas, and exposure to sunlight. Preferably, the first polymer coating 15 has an enhanced ability to resist damage from chemical attack or solvent attack by hydrocarbons, chemicals, ozone, bacteria, fungi, and moisture, as well as from skin sebum typically associated with commercial aircraft operation and maintenance.

[0045] By UV-resistant, it is meant that the first polymer coating 15 retains its appearance and physical integrity when exposed to ultraviolet radiation without excessively degrading its flexibility or mechanical properties (i.e., brittleness). Preferably, the polymer layer blocks at least 95% of UV radiation, more preferably at least 98%, and most preferably 100%. The UV opacity of the polymer coating 15 can be further reduced by including additives in the polymer material. Examples of such additives include fillers, colorants, stabilizers, and lubricants. The outer surface of the first polymer coating 15 that is not in contact with the fabric structure 16 can optionally be coated or treated with a UV-blocking material.

[0046] Ultraviolet (UV) radiation is an invisible band of radiation at the high end of the visible light spectrum. In the wavelength range of 10-400 nm, UV radiation begins where visible light ends and where X-rays begin. Because the primary exposure of composite sheet 11 to ultraviolet light is sunlight, the most important UV resistance is to low-frequency, long-wavelength light.

[0047] Preferably, the first polymer coating 15 has a soft, non-plastic feel that is ideal for products that come into contact with human skin, and maintains its toughness and flexibility over a wide temperature range, even at temperatures as low as -50°C (-60°F) over the life of the product.

[0048] In some embodiments, the outer surface of the first polymeric coating 15, i.e., the surface not in contact with the fabric structure 16, has a peel value of 263 N / m (1.5 lbs / in) or less, more preferably 438 N / m (2.5 lbs / in) or less, as measured according to ASTM D2724-07(2011)e1, Standard Test Methods for Bonded, Fused, and Laminated Apparel Fabrics, to facilitate cleaning, label removal, etc.

[0049] In some embodiments, the fabric structure 16 can be bonded to the first polymer coating 15 by means of adhesives, thermal bonding, or fasteners. The adhesive can be a thermoplastic or thermosetting resin. Thermosetting resins include, but are not limited to, epoxy, epoxy novolac, phenolic, polyurethane, and polyimide. Thermoplastic resins include, but are not limited to, polyester, polyetherketone, polyetheretherketone, polyetherketoneketone, polyethersulfone, and polyolefin. Thermoplastic resins are preferred.

[0050] Preferably, the adhesive may optionally contain up to about 40 weight percent of a flame retardant component. Suitable flame retardant components include, but are not limited to, antimony trioxide, halogenated flame retardants such as tetrabromobisphenol A, polybrominated biphenyls, pentabrominated diphenyl ether (oxide), octabrominated diphenyl ether (oxide), decabrominated diphenyl ether (oxide), and hexabromocyclododecane. Phosphorus-containing flame retardants are also widely used.

[0051] Preferably, the adhesive blocks at least about 95% of UV radiation, more preferably at least about 98%, and most preferably about 100% of UV radiation. The adhesive may further include fillers, colorants, stabilizers, and other performance-enhancing additives.

[0052] Preferably, the adhesive bond between the first polymer coating 15 and the fabric structure 16 is at least about 1.5 lbs / in. In some embodiments, the adhesive bond between the first polymer coating 15 and the fabric structure 16 is at least about 2.5 lbs / in., and in other embodiments, at least about 5 lbs / in.

[0053] The second polymer coating 19, the innermost layer of the composite sheet 11, contacts the second surface 14 of the textile component 12. This second polymer coating 19 can also be pigmented and can include ultraviolet (UV) blockers. Acceptable UV resistance is the ability to withstand exposure to intense direct sunlight for 10 years without impairing the sheet's basic mechanical and visual properties. A suitable standard is ASTM G154-16 (UVA-340 lamp, 16 hours of UV at 60±2°C and 8 hours of condensation at 50±2°C over a 240-hour period).

[0054] In some embodiments, the textile structure 17 may be bonded to the second polymer coating 19 by means such as adhesives, thermal bonding, or by fasteners. Similar adhesives as those described above for bonding the textile structure 16 to the first polymer coating 15 may be utilized here.

[0055] A typical coating for either first polymer coating 15 or second polymer coating 19 is about 75 micrometers thick and has an areal weight of about 90 gsm. The coating must have a vertical flame rating meeting UL94V-0 and be able to withstand exposure to temperatures from -40 to +60°C without compromising basic mechanical and visual properties such as flexibility, color, and transparency.

[0056] Practicality The composite sheet 11 described herein has useful fire resistance properties and is suitable as a curtain wall material for cargo containers, particularly those used on aircraft. Aircraft cargo containers are often referred to as unitary load devices (ULDs). In a preferred embodiment, when assembled into a container frame, the composite sheet 11 is positioned such that the fabric structure 17 of the textile component 12 is positioned to face a fire threat from the cargo. The direction of the fire threat is indicated by an arrow in FIG. 1. The composite sheet 11 is subject to the test methods described below.

[0057] As used in this disclosure, the term "innermost layer" refers to the portion of composite sheet 11 that faces the cargo when the composite sheet is assembled into a cargo container. As used in this disclosure, the term "outermost layer" refers to the portion of composite sheet 11 that is farthest from the cargo when the composite sheet is assembled into a cargo container.

[0058] Composite sheet 11 could also provide useful fire resistance when exposed to a fire external to the cargo container with primary structure 16 facing the flames.

[0059] Test Method Flame penetration was measured in accordance with 14 CFR 25.855 Appendix F Part III - Test Method to Determine Flame Penetration Resistance of Cargo Compartment Liner (ceiling position), which is referred to in the examples as "Test Method 1."

[0060] The composite sheet was subjected to a fire test replicating the temperature and air mass flux test conditions of test method FAA FAR 25.856(b), App. F, Part VII. The slightly lower heat flux was compensated for with a higher air mass flux to replicate the required thermomechanical stress levels imposed on the flame barrier composite sheet during a burn-through test. This is referred to in the examples as "Test Method 2."

[0061] The wash-dry cycle consisted of a 4 lb load, and each hot water wash cycle had a duration of 40 minutes. The detergent was 66 g of 1993 AATCC Standard Reference Detergent. Each drying cycle lasted 40 minutes, and the drying medium was forced cold air. [Example]

[0062] The following examples are given to illustrate exemplary embodiments of the present invention and should not be construed as limiting thereof in any way. All parts and percentages are by weight unless otherwise specified. Examples prepared according to the processes described herein are indicated by numerical values. Controls or comparative examples are designated by letter.

[0063] Example 1 The textile component 12 was assembled as shown in Figure 1. The fabric structure 16 of the textile component 12 was a 230 gsm plain weave Kevlar® fabric woven with 1500 denier yarns having a pick count of 17 threads per inch in both the warp and weft. The fabric structure 17 of the textile component 12 was a nonwoven fabric from Tex Tech Industries, North Monmouth, ME. The nonwoven fabric had a nominal weight of 239 gsm and was composed of 50 weight percent pre-oxidized polyacrylonitrile fiber type ZOLTEK™ OX and 50 weight percent Beloctex™ silica fiber.

[0064] The two fabric structures 16 and 17 were mechanically attached to one another by needle punching. In this example, the first or second polymer coatings 15 and 19 were not present.

[0065] Two samples of textile component 12 were subjected to a wash-dry cycle and two samples were not subjected to a wash-dry cycle to serve as controls.

[0066] Two additional samples of textile component 12 were impregnated with GP® 445D05 RESI-SET® so that the resin content was nominally 28.0 wt. % of the combined weight of the polyacrylonitrile fiber, silica fiber, and resin. The resin was then cured to yield rigid textile component 12.

[0067] All six specimens of Example 1 were subjected to and passed Test Method 2, in which the textile component 17 faced the flame.

[0068] It was also observed that specimens subjected to a wash-dry cycle produced less smoke and off-gassing during the flame test than unwashed specimens.

[0069] A further observation among the six test specimens of Example 1 was that after flame exposure, the resin-impregnated test specimens had significantly better residual cohesive integrity than the unimpregnated test specimens, and the washed test specimens exhibited lower residual cohesive integrity after flame exposure than the unwashed test specimens.

[0070] Example 2 This example was prepared as in Example 1, except that fabric structure 17 had an areal weight of 307 gsm. The two fabrics 16 and 17 were mechanically attached to each other by needle punching.

[0071] Test samples were prepared as in Example 1. All six samples were subjected to and passed Test Method 2, in which the textile component 17 faced the flame.

[0072] There was no significant difference in performance between the corresponding washed, unwashed, and resin-impregnated specimens of Examples 1 and 2, nor was there any apparent difference in appearance or level of physical deterioration between the corresponding specimens of these two samples during and after flame exposure.

[0073] Example 3 The textile component 12 was as in Example 1. The two fabrics 16 and 17 were mechanically attached to each other by needle punching. The textile component 12 was not impregnated with resin, thus obtaining a flexible textile component 12.

[0074] An opaque 0.075 mm (3 mil) cast polyurethane film was thermally bonded to both the first surface 13 and the second surface 14 of the unwashed specimen of textile component 12, thereby providing a first polymer coating 15 and a second polymer coating 19, respectively.

[0075] This example was subjected to and passed Test Method 2, in which the second polymer coating 19 was exposed to a flame while the fabric structure 17 was next to the second polymer coating 19.

[0076] Example 4 The textile component 12 was as in Example 1. The two fabrics 16 and 17 were mechanically attached to one another by needle punching. The textile component 12 was impregnated with GP® 445D05 RESI-SET® so that the resin content was nominally 28.0 wt. % of the combined weight of the polyacrylonitrile fiber, silica fiber, and resin. The resin was then cured to yield a rigid textile component.

[0077] An opaque 0.075 mm (3 mil) cast polyurethane film was thermally bonded to both the first surface 13 and the second surface 14 of the textile component 12, thereby providing a first polymer coating 15 and a second polymer coating 19, respectively.

[0078] This example was subjected to and passed Test Method 2, in which the second polymer coating 19 was exposed to a flame while the fabric structure 17 was next to the second polymer coating 19.

[0079] Comparative example A The textile component 12 in this example comprised a plain weave p-aramid fabric woven from 1500 denier Kevlar® K29 yarn, with 26 ends per inch in both the warp and weft and a 190 gsm plain weave E-glass fabric (ECG). The two fabrics were not mechanically entangled by needle punching, nor was the textile component resin-impregnated. In this example, there was no first or second polymer coating 15 or 19. This example failed Test Method 1, thus demonstrating the benefits provided by the second structure 17, as described above, in providing improved flame resistance.

[0080] Comparative example B This example was prepared as in Example 1, except that second structure 17 was omitted. In this example, there was no first or second polymer coating 15 or 19. The uncleaned structure failed both Test Methods 1 and 2, thus demonstrating the advantage provided by second structure 17 in providing improved flame resistance.

[0081] Comparative example C The textile component 12 of this example was assembled as shown in Figure 1. The fabric structure 16 was a plain weave p-aramid fabric woven from 1500 denier Kevlar® K29 yarn. The aramid fabric had 26 ends per inch in both the warp and weft. The fabric structure 17 of the textile component 12 was a nonwoven fabric from Tex Tech Industries. This nonwoven fabric had a nominal weight of 170 gsm and was composed of 50 weight percent pre-oxidized polyacrylonitrile fiber type ZOLTEK® OX and 50 weight percent Beloctex® silica fiber. The textile component 12 was needle-punched but not impregnated with resin. In this example, there were no first or second polymer coatings 15 or 19. Additionally, the samples were not washed. While fabric structure 17 performs well for the first two minutes of the flame test, its performance during the remaining three minutes was less than desirable, and therefore this example was deemed to fail Test Method 2 and Test Method 1. This was attributed to the low areal weight of secondary structure 17. Although it failed Test Methods 1 and 2, the composite sheet of this example may be suitable for less demanding fire resistant applications.

Claims

1. A composite sheet comprising a textile component having a first surface and a second surface, and a first polymer coating on the first surface of the textile component, wherein the textile component is A first fabric structure comprising at least one woven fabric of continuous filament yarn, wherein the woven fabric has an area weight of about 70 to about 508 gsm, A second nonwoven fabric structure comprising a blend of discontinuous fibers of oxidized polyacrylonitrile fibers and silica fibers, wherein the oxidized polyacrylonitrile fibers are present in an amount of about 30 to about 70 weight percent of the total weight of the oxidized polyacrylonitrile fibers and the silica fibers, A composite sheet that further includes the following.

2. The composite sheet according to claim 1, further comprising a second polymer coating on the second surface of the textile component.

3. The composite sheet according to claim 1, wherein the filaments of the at least one woven fabric of the first fabric structure are aromatic polyamide, aromatic copolyamide, glass, carbon, or aliphatic polyamide.

4. The composite sheet according to claim 1, wherein at least one of the first fabric structure and the second fabric structure is impregnated with a matrix resin.

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