NON-WOVEN ACTIVATED CARBON FABRIC

Abstract: An air and water vapour permeable, toxic vapor absorp­ tion non-woven fabric material comprising a web-laid sheet containing fibrillated acrylic fibre, activated carbon fibre and activated carbon particles.

Description: NON-WOVEN ACTIVATED CARBON FABRIC &verbar;, . 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 According to the present invention, a non-woven fabric material containing, as the toxic vapor absorptive ingredient therein, activated carbon particles and 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 he present invention there is provided an air and water vapor permeable, toxic vapor absorptive, non-woven fabric material comprising a) activated carbon fibers, b) activated carbon particles and c) fibrillated acrylic fibers. The novel products of the present invention are prepared by wet-laying the activated carbon fibers, activated carbon particles and fibrillated acrylic fibers from a water suspension thereof. The suspension should contain from about 5-25%, by weight, based on the total weight of fibers and particles, preferably from about 10-20%, by weight, of the fibrillated acrylic fibers, from about 10-75%,- by weight, same basis, preferably from about 15-65%, by weight, of the activated carbon fiber and from about 15-80%, by weight, same basis, preferably from about 25-70%, by weight, of the activated carbon particles, the total weight of the three components being 100%. The activated carbon particles, 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 accompliahet 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 IO.Omm, 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 heregy incorpor- ated herein by reference. The activated carbon powder or particles, have a particle size ranging from about O-L > m to about 100,m, preferably from about 1.0Sp to about 80Rgr and are also prepared from any of the carbon precursors described above. 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 equilibrium loading of absorptive carbon fiber is higher than conventional activated carbon powder products. The products of the present invention are more porous than sheets containing only carbon particles. The carbon fiber, which tends to lay parallel to the plane of the sheet, produces a longer fluid flow path through the sheet which increases the time available to absorb impurities. The novel products hereof accept an unexpectedly high additional loading of active carbon powder with only a small increase in fibrill ated acrylic fiber as compared to conventional products, i.e. see U.S. Patent No. 4,088,395. The combination of active carbon fiber and active carbon particles results in a higher performance versus cost ratio than sheets which contain only one of these active ingredients. The surface of the novel fabric material of the present invention may be embossed during or after its production to improve sheet flexibility and/or porosity. The novel nonwoven fabric material may be laminated to a woven, nonwoven, knitted etc. backing such as matts, felts, papers, etc. produced from cotton, hemp, flax, ramie, jute, silk, wool, leather, flannel, flannelette, swansdown, poplin, 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 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 14% fibrillated acrylic fibers, 18% activated carbon fiber and 68% activated carbon powder in 18 1. of water are formed into a sheet using a standard hand paper making machine. The sheet is dried under pressure at 700C to 1200C. The resultant fabric material is then tested. The results are set forth in Table I, below. Example 2 The procedure of Example 1 is again followed except that 12% fibrillated acrylic fiber, 59% activated carbon fiber and 29% active carbon powder 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 2 is again followed except that the fabric material is not embossed. After drying the material is laminated to a 65/35 polycotton fabric utilizing a commercially available acrylic foam adhesive. The results are set forth in Table I, below. Example 4 (Comparative) The procedure of Example 1 is again followed except that 45% fibrillated acrylic fiber and 55% activated carbon powder are employed. No activated carbon fibers are present. The results are set forth below in Table I. Example 5 (Comparative) The procedure of Example 2 is again followed except that 6.3% fibrillated acrylic fiber and 93.7% activated carbon fiber are employed. No activated carbon particles are present. The results are set forth in Table I, below. Example 6 (Comparative) 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 7 (Comparative) The procedure of Example 2 is employed except that 6.35 of fibrillated acrylic fibers and 93.7% of activated carbon fibers are employed. No activated carbon powder is present. Two layers of the resultant fabric material are laminated as in Example 3. The results are set forth in Table I, below. TABLE I Example No. Property S 1 2 3 4 5 ' 6 7 Weight (oz./yd2) 7.9 7.1 7.2 12.6 12.1 5.0 3.0 9.9 Thickness (Inch) 0.090 0.039 0.049 0.060 0.040 0.038 0.023 0.064 Air Permeability (ft.3/min/ft2) 46 5 21.4 15.5 0.6 .39 21.1 93 Water vapor Transmission (gm/hr/M2) 74 - 85 54 - - - Tensile Test (lbs/in) 36 18 18 65 44 2 6 2 Flexibility (Taber-g/cm) 3.1 16.0 7.0 16.0 36.5 9.8 14.0 22.0 Static CC14 Absorption (mg/cm2) 14.9 7.5 - - 15.1 5.6 2.2 10.5 Static CCl4 Sorptive Capacity (Z fabric wt.) 53.6 30.0 - - 36.9 31.9 21.9 30.1 Dynamic CC14 Absorption (mg/cm2) 2.5* 2.0* 3.5* 4.3* 6.7* 0.85* 0.05* 1.35* Dynamic CC14 Sorptive Cap. (X fabric wt.) 9.0* 8.0* 14.4* 10.1* 16.3* 4.8* 0.5* 3.9* * Calculated; based on 0.5 mg/l leakage point S = Standard commercial product (nylon knit backed polyurethane 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, activated carbon fiber and activated carbon particles. 2. The fabric material of Claim 1 wherein the concentration of fibrillated acrylic fiber ranges from about 525%, by weight, based on the total weight of fibers and particles, the concentration of activated carbon fiber ranges from about 10-75, by weight, same basis, and the concentration of activated carbon particles ranges from about 15-80%, same basis. 3. The fabric material of Claim 1 wherein the fabric material surface is embossed. 4. The fabric material of Claim 1 wherein a backing member is adhered thereto. 5. The fabric material of Claim 3 wherein a backing member is adhered thereto.

Inventors: BATTISTELLI, EDWARD, GIGLIA, ROBERT DOMENICO
Applicants: AMERICAN CYANAMID COMPANY
Application year: 1984
Main classification: D21H5
IPC codes: D21H13, A61F13, A62D5, D21H27, D21H17, B32B5, A62B17