WOVEN, NONWOVEN, AND EXPANDABLE GRAPHITE COMPOSITE MATERIAL
A composite flame barrier includes at least one layer of nonwoven flame resistant fibers, and at least one layer of heat absorbing intumescing expandable graphite held together with polymeric binders and fire resistant fibers in a sheet structure. The composite material provides thermal protection that cannot be achieved using the expandable graphite is alone. By mechanically attaching a nonwoven felt or hydro-entangled nonwoven material to the layer containing expandable graphite, the graphite becomes stabilized and is more resistant to forces that may damage the material (wind, high velocity flames etc.) and decrease or eliminate the thermal performance of the expandable graphite. The composite flame barrier is useful in applications where prolonged fire and heat resistance is required, and has an advantage of being flexible and lightweight. The uses for the material include emergency portable fire shelters, structural protection of aircraft, structural steel fire proofing, fire-rated wall assemblies, and other fire-resistant applications.
1 . A composite flame or heat barrier material, consisting of two layers:
a first layer comprising nonwoven flame resistant fibers; and
a wet-laid material in sheet form consisting essentially of (i) a heat-expandable inorganic compound, (ii) glass or other inorganic fibers, and (iii) a polymeric binder holding the wet-laid material including the heat-expandable inorganic compound together, adjacent the nonwoven fiber layer;
wherein the first layer and the sheet comprising the heat-expandable inorganic compound are attached to each other by needlepunching, quilting or stitchbonding, and wherein fibers of the first layer are positioned in the z-direction in the sheet material.
2 . The composite material of claim 1 , wherein the first layer comprises oxidized polyacrylonitrile flame-resistant fibers.
3 . The composite material of claim 1 wherein the flame resistant fibers in the first layer are 100% oxidized polyacrylonitrile fibers.
4 . The composite material of claim 2 , wherein the first layer further comprises additional flame resistant fibers selected from the group consisting of meta-aramid, para-aramid, polybenzimidazole, polyimides, polyamideimides, novoloids, poly(p-phenylene) benzobisoxazoles, poly(p-phenylene) benzothiazoles, flame retardant viscose rayon, polyetheretherketones, polyketones, polyetherimides, silica based fibers, polysilicic acid fibers derived from silica fibers, and combinations thereof.
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12 . The composite of claim 1 , wherein the first layer is attached to the sheet comprising the heat expandable inorganic compound by needlepunching.
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14 . A process for making a composite heat or flame barrier material according to claim 1 , comprising the steps of:
positioning a first layer comprising nonwoven flame-resistant fibers against a wet-laid material in sheet form consisting essentially of (i) an expandable inorganic fire resistant compound (ii) glass, or other inorganic fibers, and (iii) a polymeric binder; and
needlepunching the first layer and the wet-laid sheet material to transfer fibers of the first layer through the sheet material in the z direction.
15 . The process of claim 14 , wherein the flame resistant fibers in the first layer comprise oxidized polyacrylonitrile fibers.
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21 . The composite of claim 12 , wherein the composite is a pre-preg adapted for thermoplastic resin impregnation.
22 . The composite according to claim 12 , wherein the heat expandable inorganic compound comprises expandable graphite.