Патент USA US3090113код для вставки
May 21, 1963 w. P. CRAWLEY 3,090,103 HEAT RESISTANT FIBROUS PRODUCTS CONTAINING CERAMIC FIBERS AND METHOD OF‘ MAKING THE SAME.‘ Filed Oct. 24, 1957 I20 ' \ \ \ \ \ \ I00 — \ \ \\ \ 80 ASBESTOS FABRIC \<5_ (GRADE AAA) (STlERbNsGIL)H CERAMIC ASBESTOS BLENDED 4O ' FIBER FABRIC 2O " \\ O 700 \\\ l I l l l I l J 800 900 I000 IIOO I200 I300 I400 I500 TEMPERATURE (°F) INVENTOR. WlLLlAM P. CRAWLEYv EATTORNEY 3'90g?,1'3' Patented May 21, 1963 2 ethylene ?bers, polyamide ?bers, vinyl ?bers, and protein 3,090,163 I-EAT RESETANT FTBROUS PRQDUCTS CQNTATN lNG ENG TILE CEIC SAMEFIBERS AND METH'DD OF ?bers. The invention can best be understood by reference to several speci?c embodiments of the invention that are William P. Crawley, Tonawanda, N.Y., assignor to The described in the following examples. The drawing provides a graphical representation of the Carhorundum Company, Niagara Falls, N.Y., a cor properties of a fabric made according to the embodiment poration of Delaware Filed Oct. 24, 1957, Ser. No. 6%,2?5 5 Claims. (Cl. 28-78) of the invention described in Example I. The drawing comprises a pair of curves, each’ curve showing graphical 10 ly the relationship between tensile strength and heat re sistance of the fabric. This invention relates to ?brous products that have EXAMPLE I unusual characteristics of strength and heat resistance. The ceramic ?bers of the aluminum silicates that are Fibrous Products Made From Intimate Blends of now available have outstanding heat resistance, but their physical characteristics have restricted their use. These 15 ceramic ?bers are straight and discontinuous. They have no natural twist and are brittle and delicate. The ?bers are smooth-surfaced, so that there is little or no cohesion between the ?bers, and because there is no crimp or curl Ceramic Fiber and Asbestos Fiber An intimate blend of “Fiberfrax” aluminum silicate long staple, “medium” ceramic ?ber and carded asbestos ?ber, Cassiar grade AAA, a chrysotile asbestos, was made acconding to the method that is described in the co-pend to the ?bers, they do not cling together. Moreover, the 20 ing patent application of John W. Weber, Serial No. 658,582, ?led May 13, 1957, and now Patent 3,012,289. ?bers have low extensibility. Because of these character “Fiberfrax” is a registered trademark of The Carborun istics, these ceramic ?bers will not card on conventional dum Company, Niagara Falls, New York. The long machinery, but fall out of the machine. staple grade of “Fiberfrax” ceramic ?ber contains about Fabricated items such as paper, batts, roving, yarn, cord, rope, cloth, and non-woven structures made from 25 51.3% silica, about 45.3% alumina, and about 3.4% Zirco-nia. Fiber length is about 13/8" average, but varies various conventional ?bers, both organic and inorganic, considerably. The diameters of the “medium” ?bers are are much more limited in their resistance to heat, accord predominantly in the range 8 to 14 microns, With a mean ing to the heat resistance of the speci?c ?bers used in diameter of about 10 microns (about 2 denier). The these items. I have found that certain combinations of ceramic ?ber 30 speci?c gravity of the ?bers is about 2.73 gin/cc. As produced, the ?ber contains up to about 65% of non of an aluminum silicate with conventional ?bers can be ?brous solids or shot. made in the form of intimate blends that can be carded According to the Weber method, the asbestos ?bers on textile machinery. Fibrous products that are made were carded to form a continuous web. The Web of as from these blends are characterized by unexpected com 35 bestos carrier ?bers was divided into four widths. A binations of strength, heat resistance, and heat dissipa mass of the ceramic ?bers was opened to make a plurality tion. of small tufts, and these tufts were deposited onto each Accordingly, one object of this invention is to provide of the widths of the carrier ?bers, so that there were a plu ?brous products that have materially increased heat re rality of tufts of ceramic ?bers distributed upon each width sistance. 40 of the web of carrier ?bers. The widths of the carrier A related object of the invention is to provide an inti web, with the tufts of the ceramic ?bers distributed there mately blended ?brous mixture of ceramic ?bers of an on, were superposed to form a pile. The pile was then aluminum silicate and carrier ?bers, that can be formed carded to form a blended web of carrier ?bers and ce into ?brous products that have substantially increased heat resistance over products formed from the carrier ?bers 45 ramic ?bers. The proportions of asbestos carrier ?ber and ceramic ?ber were carefully regulated so that the alone, and that have appreciable strength. blended web comprised about 44% by weight of asbestos Another object of the invention is to provide ?brous ?ber and about 56% by Weight of- ceramic ?ber. Sub products that have greater strength at high temperatures stantially no organic impurities were present. than ?brous products previously available. The non-?brous material, or shot, was separated from According to the present invention, ?brous products, the ceramic ?bers before the tufts of ceramic ?bers were including non-woven, woven, and knitted products, are deposited on the web of asbestos carrier ?bers. made from intimate ?ber blends that contain, by weight, , The blended ?ber web was divided into several widths, between about 10% and about 95% of ceramic ?ber, to form rovings which were spun to make yarn. The the remainder being a carrier ?ber that will permit the ceramic ?ber to be processed on conventional machinery. 55 yarn was woven into a six inch Wide twill weave tape. Several pieces were cut from the tape for testing pur While ceramic ?ber that is made from substantially poses. Similar test pieces were obtained from grade pure aluminum silicate is the preferred ceramic ?ber for AAA asbestos tape of substantially the same Weight and use in accordance with the teachings of this invention, it construction, to provide a standard of comparison. The is contemplated that certain other heat-resistant ceramic ?bers could also be used, such as, for example, ?bers that 60 several test pieces were then placed in ovens, in pairs of ‘one piece of asbestos tape and one piece of blended ?ber contain aluminum silicate together with certain other in tape, at different temperatures for 24 hours. Thereafter, organic oxides, such as, for example, boron oxide, thoria the tensile strength, ASTM grab method, of the warp was and zirconia. Ceramic ?bers of this type are produced determined for each of these. The results were plotted, by processes similar to those used for mineral Wool or were reproduced in the drawing. staple glass ?bers, except that the melting point (33%0 65 andAsthethecurves drawing indicates, the asbestos fabric has supe F.) is so high that the heat of an electric arc furnace is rior tensile strength up to a temperature between 1000° required. The molten mix is formed into ?bers ‘by blow F. and 1100" F. At temperatures above 1000° F., the ing with steam or air, or by spinning from mechanical tensile strength of the fabric made from the blend of rotors. Resistance to high temperatures is unexcelled by 70 ceramic ?ber and asbestos ?ber had a considerably supe any ?ber with the possible exception of pure silica. rior tensile strength. Even at 1500" F., the fabric from Some of the carrier ?bers that may be used are acrylic the blended ?ber had appreciable tensile strength. ?bers, rayon, cotton, Wool, asbestos, glass, tetrafluoro 3,090,103 a For the ?eld of use at temperatures between about 1000“ F. and 1500“ F., therefore, the fabric from the blended ?ber is markedly superior to asbestos. Representative points on the curves are as follows: TABLE I Tensile strength, lbs. Time, hrs. Temp., ° F. Unheated tapes _________________ __ 24 ___________________________ __ Asbestos cloth Cloth from blended 159v 0 55.0 85. 0 35. 0 13. 5 __________ _ _ RJI‘. 1, 000 24. _ 1, 150 24. _ 1, 300 24____ 1,500 2.0 20.0 __________ __ 10. 5 cut, the tape undoubtedly would resist destruction under static load for a considerable period of time. On the basis of the data that is outlined above, and on» the basis of the results of other tests with other blends of‘ asbestos ?ber and aluminum silicate ceramic ?ber, andi experience with such blends, certain proportions of as-* bestos ‘to ceramic ?ber appear to be best for making in-timate blends for products for use in certain temperature-' ranges. Thus, for the range 1000“ F. to 1400" F., blends? 10 that contain ‘60% to ‘90% asbestos, and the balance alu-‘ minum silicate long staple ceramic ?ber, would o?er a‘. good combination of heat resistance, strength, and econ-' omy. ‘In the range 1400" F. to 1800” F., blends of 40% to 60% asbestos with the balance ceramic ?ber would be 15 most practical. In the range 1~800° F. to 2300“ F., blends of 10% to 40% asbestos with ceramic ?ber would be most The entries under the temperature column in Table I indi practical. Typical applications for ?brous products made cate the temperature at which the respective samples were from intimate blends of asbestos ?ber and ceramic ?ber held for 24 hours, before their tensile strength was deter include heat barriers of all types, such as for example, mined. The superiority of the asbestos fabric is evident 20 furnace curtains, lagging, ?reshields, ?re screens, heat in until temperatures on the order of about 10000 are sulating materials, and the like. Felted products made reached, but above 1100” F., the cloth from the blended from these intimate blends of ?bers are useful for high ?ber is markedly superior in strength, appearance, and temperature gas ?ltration, as Well as for many other pur hand. poses. One sample of the asbestos tape, and one sample of the 25 EXAMPLE II tape made from the blended ?ber, were held in a furnace Blends 0)‘ Ceramic Fiber and Acrylic Fiber for 24 hours at 1000" F. The weights of these samples were recorded before and after furnacing. The results are presented in Table H, below. Fibrous products made from cotton, nylon, acrylic ?ber, and cellulose acetate ?ber would have a much more broad 30 ?eld of use, if the temperature resistance were increased TABLE II even moderately. For example, in the ?ltration ?eld, the manufacture of collector bags consumes a large amount of Weight, in grams Sample Before Blended sample ____ __ Asbestos tape _______ __ special cloth annually. For example, ?lament glass cloth _' After iurnacing iurnacing 36. 56 26. 08 35. 67 21. 58 Percent loss 2. 4 17. 2 treated with a silicone resin is used extensively in the 35 manufacture of dust collector bags for carbon black col~ lection. This cloth is resistant to continuous temperatures of 400° F., and has a useful life of between 12 and 18 months. Considerable processing economies would be available if a fabric were available that could be used to The difference in weight loss is attributable in part to the 40 make these bags, and that could Withstand temperatures Organic ?ber content of the asbestos tape, which burned in the range of 500° F. up to 550° F. oif during furnacing. According to the present invention, such fabrics can In an additional test, the tape made from the blended readily be prepared by making cloth from intimate ?ber ?ber was subjected to even higher temperatures. Test blends that have predetermined proportions of acrylic car pieces of the tape were held for two hours at several rier ?ber and ceramic ?ber of an aluminum silicate. 45 different high temperatures, and thereafter, the strength A blend can be prepared of 25% by weight “Fiberfrax” characteristics were determined, as summarized below in long staple, medium ceramic ?ber and 75% by weight Table III. “Orion” acrylic ?ber. “Orlon" is a registered trademark TABLE III of the E. I. du Pont de Nemours Co., Inc., Wilmington, 50 Delaware,_for an acrylic ?ber made from polymerized Load in lbs. Percent of the acrylonitrile. The intimate blend of ?bers can be spun Temp, ° F. at the break original point; to form a yarn. The yarn has good strength and unusual heat resistance up to around 300'’ F. It can be woven strength retained to form insulating cloth, ?lter elements, gaskets, and pack 23. 5 16.0 15. 0 a 1 Completely melted. 25 17 l4 55 ings, of unusual heat resistance. Woven products made from this intimate ?ber blend can be heat treated at temperatures above about 320° F., and preferably in the range of 400°F. to 600° F., in circulating air or other oxidizing atmosphere, for su?i In another test, two one-inch wide ravelled strips of the 60 cient time to permit the acrylic ?ber to undergo a change tape were loaded with Weights, one with three pounds in character to a non-?ammable state. An exothermic (approximately 5% of breaking load at room tempera reaction takes place under these conditions, and it is be ture), and the other with nine pounds (approximately lieved that the acrylic ?ber is converted to linear, hetero~ 15% of breaking load at room temperature). The two cyclic form. The ?brous product must be held above strips were then heated gradually in an oven. After 95 65 320“ F., in contact with air, for su?icient time to permit minutes of heating, and at a temperature of 2310" F., the the reaction to be completed, otherwise, the product will strip with the nine pound load failed. After 110 minutes be ?ammable. Ordinarily, for woven fabrics, periods of heating, and at 2360° F., the strip with the three pound from one-half hour to three hours are suf?cient. When load failed. the acrylic ?ber has been heat treated in this manner, as On the basis of the foregoing data, it is apparent that described in detail in a copending patent application Serial temperatures in the neighborhood of 2350° F. are critical No. 692,206, ?led October 24, 1957, ?reproof ‘fabrics are with regard to the load breaking properties of this par obtained that have excellent heat resistance. Thus, the ticular tape. At temperatures up to about 2000° F., the yarn above can be woven to form a fabric weighing ten material exhibits reasonably good resistance to static load stresses, and if vibrations or shearing action are not pres 75 oz./sq. yd. When this fabric is heat treated as described, it can be used for ?ltration bags and for active ?lter ele 3,090,103 5 ments, and in other applications, at continuous tempera @ ?lling. This cloth had excellent heat resistance and made tures up to about 600° F. Even higher service tempera tures are permissible when the ?ber blend contains a greater proportion of ceramic ?ber. EXAMPLE III Fibrous Products Made Fram. Blends of Ceramic an excellent material for use as press cloth material. Another blended web was prepared that contained 15% by weight of ceramic ?ber and 85% by weight of rayon. This blended web was formed into yarn that was spun to form a light weight fabric that had excellent heat re sistance. This fabric had characteristics that made it a superior material for use for ironing board covers, and for similar applications where enhanced resistance to heat Fiber and Organic Fiber Several intimate blends containing 70 parts by weight 10 and scorching is important. of “Fiberfrax” long staple “medium” ceramic ?ber and ‘Intimate blends of rayon ?bers and ceramic ?bers of 30 parts by weight of carrier ?ber were prepared. The an aluminum slicate have excellent textile properties, par carrier ?bers were as follows: ticularly where the rayon ?bers comprise 70% to 85% by weight of the blend. Fibrous products from such blends Fiber: Description Cotton ___________ _. 1%" staple, from picker lap. Nylon ___________ __ 3 denier, garnett stock. “Dynel”1acrylic ?ber- 3 denier, 11/2" staple. Cellulose acetate ___~ 3 denier, 11/2" staple. 1“Dynel” is a registered trademark of Union Carbide Cor poration for its acrylic ?ber, made from a copolymer of vinyl 20 chloride and acrylonitrile. The ?ber blends were made by hand picking the com ponent ?bers and making a sandwich-type mix. The mix was then broken down vertically and re-sandwiched. This was repeated for a total of three blendings. The stock was then hand fed to a single cylinder card equipped with ring doffers and rub aprons. An examination of the blended webs from the card in dicated that the blended Webs that contained cotton and nylon had a fair degree of ?ber blending, and that the acrylic ?ber and cellulose acetate ?ber blends had a better have enhanced heat resistance with very little sacri?ce in hand, appearance, and strength. The foregoing examples illustrate certain speci?c em bodiments of the invention. It should be appreciated that many other combinations of carrier ?ber with the ceramic ?ber are possible, and are contemplated within the scope of this invention. For example, the asbestos ?ber-ceramic ?ber blends described in Example I can be modi?ed, for special purposes, by incorporating still other ?bers in the intimate blend. Generally, the ceramic ?bers range in size from about 2 to about 20 microns, although ?bers with diameters up to about 80 microns can be used successfully. In general, the ceramic ?ber constitutes at least about 10%, and preferably at least 15%, by weight of the ?ber blend, to achieve a substantial upgrading of heat resistance. The maximum proportion of ceramic ?ber that can be em Fibrous products made from the blended webs serve ad 35 ployed, under the best possible conditions, with the most suitable machinery now available approaches 95% by weight of the blend. For most high temperature appli cations, however, the preferred amount of ceramic ?ber mirably for high temperature packing and for thermal insulation. Since roping and yarn strength depend primarily upon in a blend of ?bers is on the order of 80% to 90%, that is, about 10% to 20% by Weight of the blend comprises carrier ?bers. selected for further processing, and were formed into yarn on a woolen spinning frame. The resulting yarns from both types of ?ber blends were satisfactory, although there were indications that better results would be obtained from mechanically blended ?bers. Drafts as high as 1.25 were used successfully in making the yarns. of this type are readily available in a variety of deniers. degree of ?ber blending. All of these blended webs were characterized by en hanced heat resistance and good yarn-making properties. The ceramic ?bers that can be used, in accordance with the carrier ?ber, good ?ber blending is necessary for mak ing satisfactory roping and yarn. Since the blended webs 40 the teachings of this invention, contain a major propor tion of aluminum silicate, together with small amounts containing the acrylic ?ber and the cellulose acetate were of boric oxide, zirconia, or other ?uxes. Ceramic fibers characterized by good ?ber blending, these webs were For good processing characteristics, the longer ?bers, of large diameter, are preferred. The ?ber diameters prefer ably should be predominantly in the range between 2 and 20 microns. While certain carrier ?bers have been described above in relation to speci?c embodiments of the invention, it All four blended webs, that is, the hand-picked, carded, blends of ceramic ?ber and cotton, nylon, acrylic ?ber, 50 will be understood that many suitable carrier ?bers can be used. Rayon is a highly desirable carrier ?ber for and cellulose acetate, respectively, were also hand-twisted many purposes where resistance to extremely high tem to form ropings or yarns. The twisted ropings were sus peratures is not required, because rayon is a precision pended vertically, and a small weight was then attached ?ber. The acrylic ?bers and other synthetics are also to each at its lower end. The ?ame of a match was rought into contact with each strand. The carrier ?bers 55 precision ?bers, so that processing can be facilitated by selecting, for blending with the ceramic ?ber, a carrier of nylon and cotton burned, leaving parted strands indi ?ber that will have, consistently, optimum carrier char cating no residual strength. The acrylic ?ber and cellu lose acetate ?ber blacknened and shrank, but the residues acteristics. However, the natural ?bers, such as, for ex apparently provided a bonding action which held the un~ ample, wool and cotton, can also be used. burned ceramic ?bers together, since some yarn strength 60 Some of the organic carrier ?bers that can be em ployed tend to shrink at elevated temperatures. In the remained. EXAMPLE IV ?brous products p epared according to this invention, however, ?ber shrinkage upon exposure to heat is often Blended Rayon Fiber and Ceramic Fiber not a serious problem. This is particularly true where Yarn was made by carding and spinning a blend of 80 65 the ceramic ?ber constitutes the major proportion of the parts by weight of rayon and 20 parts by weight of “Fiber ?ber blend. frax” long staple, “medium” ceramic ?ber. The rayon In any woven ?brous product made according to the was 1.5 denier, 11/2” staple ?ber. The ceramic ?ber had teachings of this invention, the ?bers are bound together a mean diameter of about 4- microns, with a minimum of by twist and ?ber to ?ber cohesion, and therefore, tensile about 2 microns, and a maximum of about 40 microns 70 strength is not substantial at high temperatures. Higher (average, about 055 denier). Staple length of the ceramic tensile strength can be obtained by inserted material such ?ber averaged about 1%", with some variation between as alloy wire. Under many conditions, a glass ?lament individual ?ber lengths. yarn, or an asbestos yarn insert, provide adequate The ?bers were carded and spun to form an eight oz./ sq. yd. cloth that had a yarn count of 15/2 warp and 75 strength, but for extremely high temperature applications 7 3,090,103 where the temperature limitations of these inserts are ex ceeded, wire is necessary. Nickel-chrome alloy wire and stainless steel Wire are good insert Wires for high tem perature applications. The ?brous products of this invention can be formed readily in substantially any desired fabricated form. For example, herringbone Weave cloth, twill Weave tape, tu bular Woven fabric with a stainless steel Wire insert, pa 3. A strong, heat-resistant fabric, adapted for service 'at temperatures in the range from about ‘1000" F. to about 1400“ ‘F. which involves maintenance of substan tial tensile strength, said fabric being woven from yarns consisting essentially of carded and spun, intimate mix tures of staple, inorganic, siliceous, ceramic ?bers con taining a major proportion of aluminum silicate and staple carrier ?bers consisting essentially of asbestos, said per, batts, blankets, roving, yarn, cord, rope, and the ceramic ?bers constituting from about 10% to about like, can be produced readily. 10 40% by weight of said fabric. The ceramic ?bers provide heat-resistant and heat 4. A strong, heat-resistant fabric, adapted for service di?’using members in the products, and thus upgrade the at temperatures in the range from about 1400° F. to heat resistance. The ceramic ?ber offers particular ad about 1800" F. which involves maintenance of substan vantages in products where previous failures had been tial tensile strength, said fabric being woven from yarns caused by a surface or localized heat condition. 15 consisting essentially of carded and spun, intimate mix ' Speci?c ?brous products that may be improved, ac_ tures of staple, inorganic, siliceous, ceramic‘ ?bers con cording to the teachings of this invention, include lami— taining a major proportion of aluminum silicate and nating paper for high temperature applications, laundry staple carrier ?bers consisting essentially of asbestos, said cloths, and many other textiles for high temperature ap ?bers constituting from about 40% to about plications. Many other speci?c ?brous products are 20 ceramic 60% by Weight of said fabric. mentioned above. , _ While the invention has been described in connection 5. A strong, heat-resistant fabric, adapted for service at temperatures in the range from about 1800° F. to with speci?c embodiments thereof, it will be understood that it is capable of further modi?cations, and this ap ‘about 2300° F. which involves maintenance of substan adaptations of the invention following, in general, the principles of the invention and including such departures consisting essentially of carded and spun, intimate mix tures of staple, inorganic, siliceous, ceramic ?bers con taining a major proportion of aluminum silicate and tial tensile strength, said fabric being woven from yarns plication is intended to cover any variations, uses, or 25 from the present disclosure as come Within known or customary practice in the art to which the invention per tains and as may be applied to the essential features herein before set forth, and as fall within the scope of the invention or the limits of the appended claims. I claim: 1. A blended, ?brous product characterized by a high degree of strength retention at temperatures between 35 ‘staple carrier ?bers consisting essentially of asbestos, said ceramic ?bers constituting from about 60% to about 90% by weight of said fabric. References Cited in the ?le of this patent UNITED STATES PATENTS 2. A strong, heat-resistant fabric, adapted for service 451,115 1,486,800 2,132,702 2,266,907 2,306,781 2,401,389 2,424,743 2,467,889 at temperatures in the range from about 1000° F. to ' 2,557,834 McMullen ____ __' ____ __ June 19, 1951 about 2300" F. which involves maintenance of substan tial tensile strength, said fabric being woven from yarns consisting essentially of carded and spun, intimate mix tures of staples, inorganic, siliceous, ceramic ?bers con~ 2,626,213 2,643,437 Novak ______________ __ Jan. 20, 1953 Parker ______________ __ June 30, 1953 540,018 764,417 Canada ______________ __ Apr. 23, 1957 Great Britain ________ __ Dec. 28, 1956 1000’ F. and 2000° F. and consisting essentially of an intimate carded mixture of staple, inorganic, siliceous, ceramic ?bers containing a major proportion of alumi num silicate and’staple carrier ?bers consisting essen tially of asbestos,'said ceramic ?ber constituting from about 10% to about 90% by weight of said product. taining a‘major proportion of aluminum silicate and staple carrier ?bers consisting essentially of asbestos, said ceramic ?bers constituting from about 10% to about 90% by weight of said fabric, Emsley ______________ __ Apr. 28, Riesenberg __________ __ Mar. 11, Simpson ______________ __ Oct. 11, Riehl _______________ __ Dec. 23, Francis ______________ __ Dec. 29, Truitt ______________ __ June 4, Davis _______________ __ July 29, Harter et al. _________ __ Apr. 19, 1891 1924 1938 1941 1942 1946 1947 1949 FOREIGN PATENTS OTHER REFERENCES “Modern Textiles,” September 1957, page 61.