NON-WOVEN ACTIVATED CARBON FABRIC

Abstract: An air and water vapor permeable, toxic vapor absorp­ tive non-woven fabric material comprising a wet-laid sheet containing fibrillated acrylic fiber, and an activated carbon constituent selected from the group consisting of activated carbon fiber and activated carbon particles.

Description: NON-WOVEN ACTIVATED CARBON FABRIC BACKGROUND OF THE INVENTION The need for protective clothing has long been recognized by both military and commercial personnel. The manufacture and use of certain dangerous chemicals such as pesticides, toxic materials etc. in the form of sprays or mists, gases etc. requires that personnel involved therewith be provided the safest protective clothing available. Protective clothing has, in the past, been manufactured from completely impermeable materials such as plastics or oilskin. These products did not prove sufficient however, due to preventing the egress of heated air and perspiration from the wearer. Other attempts to provide protective clothing involved the use of absorbent charcoal or other materials in particulate form, however, these products also involved difficulties due to the loss of the particulate material over a period of time. The use of quilted woven carbon cloth and adhesives to bind the carbon particles, also was less than commercially successful, see U.S. Pat. Nos. 3,586,596; 3,769,144. Accordingly, if a fabric configuration could be developed which overcame the disadvantages of previous fabrics, a step forward in the art would be achieved. SUMMARY OF THE INVENTION Non-woven fabric material containing, as the toxic vapor absorptive ingredient therein, activated carbon particles and activated carbon fiber is disclosed in U.S. Application Serial No..531,366, filed September 12, 1983. According to the present invention, a non-woven fabric material containing, as the toxic vapor absorptive ingredient therein, activated carbon particles or activated carbon fiber, is produced via the wet-laying process, utilizing fibrillated acrylic fibers as the binder material, the product being air and water vapor permeable and providing the user protection from dangerous chemicals in liquid or gaseous form. DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS In accordance with the present invention there is provided an air and water vapor permeable, toxic vapor absorptive, non-woven fabric material comprising (a) fibrillated acrylic fibers, and (b) an activated carbon constituent selected from the group consisting of activated carbon fiber and activated carbon particles. The novel products of the present invention are prepared by wet-laying the activated carbon constituent (activated carbon fibers or activated carbon particles) and fibrillated acrylic fibers from a water suspension thereof. In the embodiment of the invention wherein the activated carbon constituent is activated carbon fiber, the concentration of fibrillated acrylic fiber may suitably range from about 5 to about 60% by weight, based on the total weight of the acrylic fibers and carbon fiber, and the concentration of the carbon fiber will be in the range of from about 40% to about 95%, by weight, on the same basis, the total weight of the two components being 10070. In the embodiment of the invention wherein the activated carbon constituent is activated carbon particles, the concentration of fibrillated acrylic fiber suitably may be in the range of from about 3570 to about 65%, s by weight, based on the total weight of acrylic fibers and carbon particles, and the concentration of activated carbon particles suitably is in the range of from about 35% to about 6570s on the same basis, the total weight of the two components being 100%. The activated carbon constituent (activated carbon particles or activated carbon fiber) and fibrillated acrylic fiber are wet-laid using the conventional papermaking process well known in the art. Flocculating agents and surface active agents can be incorporated into the water suspension in order to facilitate the paper making procedure as is also known in the art. The acrylic fiber may be produced from any known acrylic polymers such as polyacrylonitrile, copolymers of acrylonitrile and other copolymerizable monomers such as methyl methacrylate, ethyl acrylate etc; homopolymers and copolymers of other fiber forming monoethylenically unsaturated monomers such as vinyl acetate, vinyl chloride, styrene, vinyl pyridine, acrylic esters, acrylamide and the like. Fibrillation of the acrylic fibers, which should range from about lmm to about 25mm in length, is also accomplished as is known in the art i.e. such as by high speed shearing of the fibers. The activated carbon fibers are also well-known in the art as are methods for their production. They can be used in lengths of from about 0.3 to about 15.0mm, preferably from about 0.5 to about 10.0mm, and can be prepared from such carbon fiber precursors as coal tar pitch, petroleum pitch, coal tar, petroleum derived thermal tar, ethylene tars, high-boiling coal tar distillates, ethylene tar distillates, gas oils or polynuclear aromatics. Also useful as precursors are polymers such as acrylonitrile homopolymers and copolymers, polyvinylalcohol, and natural and regenerated cellulose. Methods for preparing activated carbon fibers useful herein are disclosed in U.S. Patent Nos. 4,069,297 and 4,285,831, which patents are hereby incorporated herein by reference. The activated carbon powder or particles, have a particle size ranging from about 0.lem to about lOOpm, preferably from about 1.01-im to about 80pm and are also prepared from any of the carbon precursors described above. Regardless of whether activated carbon fiber or ac tivated carbon particles are utilized as the activated carbon constituent of the non-woven activated carbon fabric of this invention, the surface area of the carbon constituent, as measured by BET determination, desirably is greater than about 500M2/gm and preferably greater than about l,OOOM2Igm. Although most commercially available activated carbon materials do not have surface areas greater than about 2600M2/gm, as measured by BET determination, the so-called very high surface area activated carbons which have surface area values as high as 3500M2/gm are particularly advantageous in the practice of the present invention. As associated with the desirability of providing a high degree of structural integrity to the non-woven fabric material of the present invention, it is preferred in practice that the particle size distribution of activated carbon particles utilized in the invention should include no more than 15% by weight of particles above 500 microns diameter and no more than 15% by weight of such particles below 10 microns diameter. Correspondingly, the particle size distribution of activated carbon fiber preferably includes no more than about 15% by weight of such particles of fiber diameter below about I micron and no more than about 15% by weight of such fibers with diameter above 100 microns. In general, it is satisfactory if the length of the carbon fibers is in the range of from about 100 microns up to about 2 centimeters. The wet-lay sheet making process (papermaking) used herein for the production of the novel fabric material of the present invention, results in a product having unique sorptive characteristics, a thickness of at least about 0.005, preferably at least 0.01, inch, a high sorptive capacity to weight ratio and high porosity to fluid flow. The surface of the novel fabric material of the present invention may be embossed during or after its production to improve sheet flexibility andlor porosity. The novel non-woven fabric material mav be laminated to a woven, non-woven, knitted etc. backing such as matts, felts, papers, etc. produced from cotton, hemp, flax, ramie, jute, silk, wool, leather, flannel, flannelette, swansdown, ooplin, cellulose ethers or esters, nylon, rayon, acetates, polythene, glass, rock wool, asbestos, in order to strengthen the material. Lamination of the novel products hereof to the abovementioned backing materials may be achieved by the use of water vapor and air #permeable adhesives, preferably those available in the form of foams, such as rubber or acrylic latexes, polyurethanes and the like. These adhesives are self-adhering and upon curing foam and set into strong bonds. The surface of the novel fabric material claimed herein may be rendered hydrophobic by coating with a porous silicone film or a polymer such as polytetrafluoroethylene. Additionally, a reactive coating capable of decomposing toxic agents, e.g. a coating of a sulfonated polymer to hydrolyze nerve gas, may be applied thereto so that the activated carbon particles and/or fibers form a second line of defense. The fabric material of the present invention has a wide variety of uses. It is useful for protective purposes and for filtration and separation of gases. The uses include the manufacture of the fabric material into wearing apparel e.g., military uniforms; blankets, sleeping bags, bedding, surgical dressings, wrappers and containers, covers, tarpaulins, tents, curtains, gas masks, paint spraying masks, air-conditioning duct filters, flue gas deodorizers and the like. The following examples are set forth for purposes of illustration only and are not to be construed as limitations on the present invention except as set forth in the appended claims. All parts and percentages are by weight unless otherwise specified. Example 1 A mixture of 45% fibrillated acrylic fiber and 55% activated carbon powder in 18 liters of water is formed into a sheet using a standard hand papermaking machine. The sheet is dried under pressure at 7000 to 12000. The resultant fabric material is then tested. The results are set forth below in Table I. Example 2 The procedure of Example 1 is again followed, except that 6.3% fibrillated acrylic fiber and 93.7% activated carbon fiber are employed and the paper material is embossed after forming but before drying. The results are set forth in Table I, below. Example 3 The procedure of Example 1 is again followed except that 19.4% fibrillated acrylic fiber, 80% activated carbon fiber and 0.6% polytetrafluoroethylene are employed. No activated carbon powder is present. The results are set forth in Table I, below. Example 4 The procedure of Example 2 is employed except that 6.3% of fibrillated acrylic fibers and 93.7% of activated carbon fibers are employed. Two layers of the resultant fabric material are laminated to a 65/35 polycotton fabric utilizing a commercially available acrylic foam adhesive. The results are set forth in Table I, below. TABLE I Example No. Property S 1 2 3 4 Weight 2) 7.9 12.1 5.0 3.0 9.9 Thickness (Inch) 0.090 0.040 0.038 0.023 0.064 Air Permeability (ft/min/ft) 46 0.6 .39 21.1 93 Water Vapor Tran smision (gm/hr/M) 74 - - Tensile Test (Ibs/in) 36 44 2 6 2 Flexibility (Taber-glcm) 3.1 36.5 9.8 14.0 22.0 Static CCl4 Absorption (mg/cm) 14.9 15.1 5.6 2.2 10.5 Static CCl4 Sorptive Capacity (% fabric wt.) 53.6 36.9 31.9 21.9 30.1 Dynamic CCl4 Absorption (mg/cmê) 2.5* 6.7* 0.85* 0.05* 1.35* Dynamic CCl4 Sorptive Cap. (% fabric wt.) 9.0* 16.3* 4.8* 0.5* 3.9* * Calculated; based on 0.5 mg/l leakage point S = Standard commercial product (nylon knit backed poly urethane foam cont. activated carbon powder)

Claims: WE CLAIM: 1. An air and water vapor permeable, toxic vapor absorptive, non-woven fabric material comprising a wet-laid sheet containing fibrillated acrylic fiber, and an activated carbon constituent selected from the group consisting of activated carbon fiber and activated carbon particles, wherein the concentration of fibrillated accrylic fiber ranges from about 5-65% by weight based on the total weight of fibrillated acrylic fiber and activated carbon constituent, and the concentration of said activated carbon constituent ranges from about 35-95%, by weight, same basis. 2. The fabric material of Claim I wherein the fabric material surface is embossed. 3. The fabric material of Claim 1 wherein a backing member is adhered thereto. 4. The fabric material of Claim 2 wherein a backing member is adhered thereto. 5. The fabric material of Claim 1 wherein the surface area of the activated carbon constituent, as measured by BET determination, is greater than about 500M2/ gm. 6. The fabric material of Claim 1, wherein the activated carbon constituent is activated carbon particles, wherein the concentration of fibrillated acrylic fiber ranges from about 35-65%, by weight, based on the total weight of fibrillated acrylic fiber and activated carbon particles, and the concentration of activated carbon particles ranges from about 35-65%, by weight, same basis. 7 The fabric material of Claim 1, wherein the activated carbon constituent is activated carbon fiber, wherein the concentration of fibrillated acrylic fiber ranges from about 5-60% by weight, based on the total weight of fibrillated acrylic fiber and activated carbon fiber, and the concentration of activated carbon fiber ranges from about 40-95%, by weight, same basis. 8. The fabric material of Claim 6, wherein the particle size distribution of activated carbon particles contains no more than about 15%, by weight based on weight of the particles, of particles with a diameter above about 500 microns and no more than about 15% by weight, same basis, of particles with a diameter below about 10 microns. 9. The fabric material of Claim 7, wherein the distribution of fibers having a diameter below about 1 micron does not exceed about 15% by weight of the total activated carbon fiber content, and the distribution of activated carbon fibers having a diameter above about 100 microns does not exceed about 15% by weight, same basis. 10. The fabric material of Claim 1 wherein the surface area of the activated carbon constituent, as measured by BET determination, is greater than about 1,000M2/gm.

Inventors: BATTISTELLI, EDWARD ANTHONY, GIGLIA, ROBERT DOMENICO
Applicants: AMERICAN CYANAMID COMPANY
Application year: 1986
Main classification: D21H13
IPC codes: A62B17, D21H17, B01D39, B01D53, D21H13, B65D81, A62D5, A41D31, D21H21