n HENRY S. GREW, JR. Wellington Sears GO., 65 Worth S t . , New York, N. Y e
HERE are beveral aspects to the question of the advantageb and disadvantages of man-made fibers as applied to industrial applications. In industrial end uses the most important fiber today, by far, is cotton. Enormous quantities are produced yearly in various parts of the world, and although its price fluctuates wildly, being an agricultural product, it is a relatively low cost raw material for the textile industry. Cotton possessee many outstanding properties and characteristics, and, in view of its widespread availability, is being used in a wide variety of industrial products constituting a very large market. Probably the first industrial fabrics were the flax and cotton aails which have been used on vessels for centuries. The Introduction of the steam engine resulted in the abandonment of the old sailing vessels and clipper ships which required large quantities of heavy sailcloth. Then came the rapid development of the automotive and rubber industries, which resulted in vast new markets for industrial fabrics, It was a long time, however, before textiles were considered engineering materials. The real need for standard specifications for the cotton fabrics used in the manufacture of pneumatic tires finally resulted in the establishment of a committee for these fabrics in the American Society for Testing Materials. Now the society has a large number of active committees in this section covering a wide variety of industrial textiles. Prom the foregoing remarks it is evident that cotton fabrics are well established in the industrial field. I n recent years, however, the textile industry has benefited tremendously from chemical research which has had such far-reaching effects in other industries. Many man-made fibers-the direct results of this chemical re-
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jearch-are no-iv commercially available in quantity and iiiiportant industrial applications are being found for them. There arc others in the development stage showing great promise for industrial uses; these will be available in the near future. A+ previously noted, since cotton is an agricultural product it is subject to wide fluctuations in price. Furthermore, government loan supports on cotton have kept the price above its natural level with the result that man-made fibers have largely replaced cotton cords used by the tire industry, the most important single use for industrial textiles. The production of about 300,000,000 pound? of high tenacity filament rayon, largely for use in tire production. has displaced about 700,000 bales of cotton, according to recent estimates. AVAILABILITY O F M&N-MAUE FIBERS thr Few developments have had such far-reaching efferta manufacture of textile fibers. The first “artificial silk” yarn6 were made about 60 years ago in France. I n 1923 the production of artificial silk totaled about 35,000,000 pounds. The industry has expanded very rapidly since that time, and it is estimated that world production of man-made fibers this year viill exceed 3.5 billion pounds, representing approximately 10% of the total fiber consumption for all textile uses. Whether this rate of growth will continue is problematical as there are reasons to believe that the rate of growth in the years t o come will not be so rapid. The greatest work to be done at the present time is the improvement of the characteristics of the large number of fibers already available and their adaptation to present needs
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An inherent advantage of a man-made fiber is that it can be consumer end uses. Cost and style factors are of vital importanee produced uniformly, whereas natural fibers are subject to a in this type of textile operation. Accordingly, fabric construavariety of climatic conditions and blights. The raw material tions are subject to constant change. This situation is important going into fiber manufacture can be controlled precisely, and manto the user of textiles for industrial purposes, as uniformity of ufactured fibers, being chemical products, are subject to formulas product and continuity of supply are of very great importance. that ensure close control a t all stages of production. Also, chemThere is an opportunity here for the machinery manufacturer, ical products are far more stable from a price standpoint; based in cooperation with the fiber producers, to develop universal on past experience, the price of a manufactured fiber is conequipment adaptable to the processing of all fibers. I n order stantly being lowered as production increases and improvements to meet satisfactorily the great variety of end-use requirements, an in manufacturing techniques are effected. This means that plans industrial fabric manufacturer would be in a far better position to can more readily be made in textile manufacture for standardized produce the range of fabric constructions necessary on an ecoproducts and production. nomical basis. This would be a distinct advantage in adapting Needless to say, availability of raw material is a most important man-made fibers to industrial uses. consideration in the development of a new industrial application. Most manufactured fibers have been developed primarily for apparel and household purposes. Accordingly, in view of the vast BASIC FIBER PROPERTIES AND YARN CHARACTERISTICS markets in these fields, fibers that have proved satisfactory for Another advantage for man-made fibers is their ability t o be these uses are readily available but constitute new sources of raw produced in three basic forms-namely, monofilament, continmaterials for the industrial textile engineer. This has been the uous multifilament, and staple, the type selected depending on case in the development of viscose rayon which, as previously the particular end-use requirements. Monofilament yarns are noted, goes back quite a number of years. Until the development used for screenings and certain industrial filter cloth applications. of high tenacity continuous filament yarns, viscose rayon had no Where a yarn or fabric is required with optimum strength-weight industrial uses. With the development of high tenacity yarns, ratio, a continuous filament yarn is the type selected. Staple however, there was a rapid expansion in the industrial field. The fibers, on the other hand, spun into yarns on conventional textile successful adoption of this type of yarn in the manufacture of equipment, are in a quite different category. The tensile pneumatic rubber tires is well known. strength of such yarns depends not only on the basic fiber The three basic yarn systems used by the textile industry are strength but also on the frictional hold of the yarns themselves, the cotton, wool, and silk. These particular natural fibers have imparted during yarn spinning and possible subsequent twisting been by far the most important in this country in textile manuoperations. This frictionnl hold may be increased in staple yarns facturing over a long period of time. Textile machinery manuby resin and heat treatments. However, where tensile strength facturers have adapted all their equipment in the past to these is of prime importance, a continuous filament yarn has decided basic fibers, and systems of yarn production and handling have advantages. Furthermore, the bulk factor is lower in filament been devised which are particularly suited for the processing of yarn, and this also has important industrial significance, these fibers. This condition has led to the development of three On the other hand, in many industrial applications tensile important divisions of the textile industry, and only in rare instrength is not of such great stances do manufacturing imDortance. I n fact. over concerns venture outside their the years far too much emcomparison is made between the newer synthetic normal scope of operations. phasis has been placed on this fibers and cotton with respect to their importance in The production of textiles physical property of textile industrial textile applications. I t is shown that one made from man-made fibers materials. It is a property inherent advantage of synthetic fibers is that they can be has tended to follow along that can readily be measured produced with precise uniformity. In a review of industhese same lines. This has reby all textile laboratories, and trial applications of these fibers, the rubber industry sulted in the manufacture of i t is incorporated in a vast stands out in importance because of its exacting fabric man-made yarns and fibers number of fabric specificarequirements for tires, mechanical hose and belting, and which are adaptable to the a variety of coated products. Another significant use for tions. However, in many a p conventional yarn systems. plications other mechanical synthetic fabrics is in the reinforcement of plastic lamiConsequently, the production characteristics such as abranates. The chemical and allied industries also use the new of industrial fabrics made sion resistance, resistance to fabrics for filter media, anode bags, and electrolytic cell from these new fibers has dediaphragms. The varying conditions and requirements flexing, and cushioning effects veloped in all branches of the are of far greater significance. found in these applications are discussed in some detail. industry and at various cost I n these and other fields, it is the task of the textile techThe bapic physical unit in levels. It has also brought nologist to use his knowledge of the fundamental properyarn production is the fiber about significant changes in ties and characteristics of all available fibers to make the in filament or staple form. the manufacturing operations correct selection for each specific end use. Textile materials used for of textile concerns well estabmany industrial applications lished in the industrial field. __ are subject to various typea The adoption of existing of mechanical action requirequipment and the installa- tion of new machinery to ing yarn of sufficient elasticenable cotton manufacturing companies to produce filament ity to enable it to move about while being flexed or distorted fabrics is a good example of the changes which are taking and return to its original condition. I n yarns produced from staple, the fibers are in a better position place. This has been necessary to enable these concerns to maintain those industrial markets which have been encroached on by to move about when subjected to distortion and retain their inherent position in the yarn structure. The frictional hold of the other textile manufacturers. The latter include textile manufacturing concerns that have been dominant in the silk and confibers with the yarn and the elasticity of the fibers themselves are the factors involved. However, if these bending and flexing tinuous filament rayon fields, producing fabrics largely for the apparel trades. These companies, with few exceptions, are stresses are b o great or if they continue over a period of time, largely geared to the production of fabric constructions in very ultimate failure of the yarns will occur a t the wear point. On the September 1952
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Dynel, t'nion Carbide's New Fiber, Is Used in Diaphragms with Filter Plating Solution in a Large Copper-Plating Tank The dyne1 filter cloth has resistance to deterioration from acids, good wet and dry strength, and dimensional stabilit,; it.; life is far longer than material previously u b e d , thereb, efferting ~ i h stantial economies in oprrating. costs
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other hand, compact continuous filament yarns of high fiber density, although possessing high tensile strength, do not lend t,hemselves to many industrial applications involving these other types of mechanical wear and distortion. I n the pa.st the great bulk of the man-made yarns produced have been of the continuous filament type. However, an increasing percentage OC this production is going into staple form. This has also been true in the development of industrial fabrics from manufactured fibers. Continuous filament construct,iom have been extensively used for industrial purposes, but staple fi1)er fabrics are finding many uses and, in fact, are replacing the older continuous filament types in some instances. At this point, i t should be stressed that the basic physical properties of the various fibers, which are widely known, do not iiecessarily follow through into the final product. The yarn properties are the most important t o consider in the selection of a fabric €01. a n industria.1 purpose. I n continuous filament yarns, the denier, number of filaments, and twist are the variable factor8 involved for a given fiber, whereas in staple fiber yarns, staple length, fiber denier, degree of fiber crimp, and twist must be considered. Nylon possesses high tensile strength combined with high elasticity. It is able t o absorb more energy than any other fiber, which makes it particularly significant from an industrial standpoint. XyIon is also considered the most resistant to abrasion. Its high stretch characteristic, although highly advantageous in certain applications is a disadvantage a t this stage of development for other end uses, such as tension members in conveyor belts and V-belts. Glass fiber, on the other hand, tias an extremely low degree of stretch. *4ccordingly, even though it possesses very high tensile strength, its ability to absorb energy is poor, thereby limiting its 2142
use. Glass film,, Lon evttr, I m oiitstaiidirig lieltt icesistuuce aiid ia incombustible. Furthermore, i t ia dimernionally stable. These properties make it an excellent fiber for certain industrial applications. High tenacity rayon, as previously rioted, is a man-made fiber that ha8 had a tremendous impact, on the textile industry. The yarn, a cellulofiioproduct, possesses excellent, tensile strength, not only on account of its inhereut fiber strength but also because it, i u produced ill continuous filament lorrn. Although not a8 stroug as nylon, i t is much cheaper t o produce, ill view of tlie lower cost raw inaterial used. Balancing out these factors, the textile eugineer finds that from a t,ensile strength standpoiut, it in aii economical fiber t,o use. It doe9 have a serious disadvantage iii that it is adversely affected by moisture. The fiber has a high moisture regain as compared t o riataral cellulosic fibers surh ali cotton. It also loses a high percentage uf its streiigth wheri \vet. Elowever, an improved high tenacity rayon has receiitly h e i r developed possessing higher wet and dry Mtrength. The iiew yarn, furthermore, does not lose as high a percentage of its r l r ~ . st,rength when saturated with moisture. The acrylic fibera, such as Orlon, dynel, rlcrilaii, and the newest one, X-51, are, from an industrial slaridpoint, characterized by their chemical resistance. These fibers, which are considered wool eubstitutea, will undoubtedly find their biggwt market# iu apparel and household uses because o f their vvool like characteristics. l'ossessing outst~andingchemical resistance to strorig acid solutions even a t elevated temperatures, acrylic fiber3 have fouiiti importaut applications in chemical a d allied iiidustriee. These fihers are also hydrophobic and thL c:lmra(%eristiccan be utilisoii to advantage in certain electrical applicatioiis. Or1011 is outstanding in its resktance to suuliglit a,nd, like o t l w truly synthetic fibers, is highly re&tsnt to uiildew and bacteria growths. Tlynel, in additiou t o t'he cliaracteristiuu previolwly meutioiie~l, does not support, combustion. E'urthermore, ita seusitivity t u heat e m be utilized industrially t o t,he ext,ent that fabrics mmiifactured from this fiber car1 be preformetl l)y the applic,ntiori oi' heat and pressure. Another new fiber with indusilGd aigiiifioitncris 1)acroii. Wiis synthetic fiber produced from tt polyester resin cornbiiiep higli tensile strength with high stret,ch resistance. One of tlie early synthetic fibers having industrial useti was Viriyon-CF fiber. Produced in ooiitiuuous filuinent form, it possessed outstanding chemical reuistauce together wiih liigli strength and w a k r resiataiioe. iIowever, it had one very seriour drawback, not, only from the si:tndpoiiit of text.ile u s r s but a l ~ o industrially. This \WH its v l n w softeuing point of 65" C. The yarn was used prii~cipallj oliemically resistant filter cloth and anode bags, but the small productioii involved did not, warrnut the continued rnaiiufacture ~ i iliin ' yarn on a, coinniercial baks. The low softeuing poiiit has been utilized to :dvantagv, however, and Vinyon-CT? staple filxr in today beiiig used ver?' successfully BR a loading fib n (,he productioii 01 noiiwoven fabrics, papers, and felta. l'he Lhernq)le,ntic nai.ui~t3oi' ( l i e fii)e?. is riovi heing usetl to defiiiiir :i,(Iviint,:tge. Ih 1)llSTKIA I, .Al'PI,lCA'L'IONS
Tn designiug a fab1,ic Fur. LL ypccifio industrial application, {lie necessary elid-use requireuieut H must, first be carefully considered. Then the fabric engineer, through a knowledge of fiber properties and characteristics, is in a positiou i o select the most suitable fiber or fiber combination and design a textile material for a specific: end use. Comniercial feasibility is of the utmost iniportance in the development of any indust,rial product,, mid thin extremely important factor cannot be overlooked if time and expense are to be used to the best advantage. Iixteusive laboratory and plant. tests must be conducted to determiue the practicability of the textile product before it can be used couirnercially. These teste
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SYNTHETIC FIBER often extend over long periods of time before the answer/ is obtained. Rubber Industry. The rubber industry is one of the largest users of mechanical textiles. Rubber and fabric can be combined in limitless combinations to provide a wide range of useful products for both the home and industry. I n addition, rubberized products are of vital importance t o the military establishment, Man-made fibers already have made tremendous gains, not only’in replacing cotton in many products because of economic considerations, but also in effecting new and improved materials. High tenacity rayon and nylon cords and cord fabrics, as previously indicated, have had a tremendous impact on the tire and mechanical goods industries. These fibers are of particular significance in the manufacture of heavy-duty truck and bus tires as well as special tires for aircraft and premium tires for automobiles. With improved textiles (cotton as well as those produced from man-made fibers) the effective life of automobile tires steadily increases. Many of you will recall the time when the life of an automobile tire was well under 10,000 miles. Tires now last up to five times this mileage. It has been said that from an economic standpoint alone cotton would be completely out of the picture if the necessary quantities of man-made fibers were available. Cord fabrics made from high tenacity rayon are being used in production of conveyor belts. Here again, strength, combined with lightness in weight and cost considerations, are the reasons for the use of a man-made fiber. The tension member of V-belts is still another place for high strength fibers with suitable stretch characteristics such as rayon. Transmission belting, steam hose, and diaphragms are other important applications in which fibers such as rayon and nylon are finding a place. I n the manufacture of circular and braided hose, a much lighter weight product, yet one possessing the same strength and durability, can be obtained by the use of man-made fibers. For military applications a wide range of filament nylon and high tenacity rayon fabrics has been developed for such products as rubberized pontoons, life rafts, fuel cells, and storage tanks. Lightweight rubberized nylon fabrics with high strength characteristics are being used for steadily increasing quantities of protective coverings of all types. Spun nylon fibers have been used for jungle boot tops. Here, again, the abrasion resistance and resistance to flexing of these fabrics are significant, as well as their resistance to tropical conditions. So-called impression fabrics for embossing effects provide another application for special filament yarn fabrics, and manmade fibers are also being tried out for liners in rubber processing. It can readily be seen that the use of man-made fibers will expand greatly in the rubber industry as the necessary fibers become more readily available and experimental work progresses on new and improved fibers. Laminates. Another important field for man-made fibers is the laminating industry, which is divided into the so-called high and low pressure branches. Synthetic fibers have made the greatest advances in the low pressure branch of the industry. Here glass fiber fabrics combined with polyester type resins played an important role in the World War 11,particularly in the aircraft industry. As a reinforcement material for plastic laminates used in aircraft construction, glass fiber has the advantage of high tensile strength combined with lightness of weight and dimensional stability. Resins and glass fiber in combination have outstanding physical characteristics, both from the standpoint of mechanical strength and their ability Bo be formed into a wide variety of useful producte. Their importance in aircraft construction, particularly for military uses, has been indicated. Laminated glass fabric is also being used in the hull construction of small boats, and its military possibilities are evident, as strength, lightness in weight, and durability are essential requirements. An unusual example of glass fiber in combination with resin is the fishing rod. The September 1952
high degree of flexibilitv and strength reclui very sa&factory resuits by the i s e of glass fiber reinforced plastics. In phenolic resin laminates and under high pressure conditions, man-made fibers have also found a place, There is an important classificationof laminates of this type used for electrical purposes. Needless to say, insulating characteristics are of great importance for electrical laminates in electronic equipment to be used under diverse operating conditions. Also, adequate mechanical properties are required as well as high heat resistance in the case of many applications. Here again, the adoption of man-made fibers has resulted in the development of new and improved products. Glass and nylon fibers are being used at the present time and the newer acrylic fibers such as Orlon are in the development stage. Electrical Equipment. Another important field to consider in the application of man-made fibers is the electrical industry. The significance of plastic laminates for electrical applications has been mentioned, but there are other uses requiring large quantities of textile materials. Glass fiber has the advantage of high heat resistance for this type of end use. It is being widely used for insulating purposes because of the additional advantages of low moisture absorption and excellent electrical characteristics. Glass fiber yarns, cords, tapes, and sleevings are the forms commonly employed. The incombustibility of the fiber, with the consequent elimination of f i e hazards, makes it particularly well suited for wire insulation. Industrial Equipment. Textile materials are also extensively used by the chemical and allied industries for filter media, anode bags, and electrolytic cell diaphragms. For these uses the fabric is utilized as a supply item; it is not incorporated into the final product as in the applications for industrial textiles previously described. There are two broad classifications of filtration to be considered in filter cloth applications-namely, wet filtration and dust collection. The first type comprises a wide range of processing equipment, including filter presses, rotary drum vacuum filters, vacuum and pressure type leaf filters, and gravity filters. Filter presses in general require relatively heavy, firmly woven fabrics of various textures which will not only retain and support the filter cakes formed during operation of the press but also act as an effective gasketing material. As the cloths are subjected to relatively high operating pressures during use and severe mechanical wear a t the gasket edges, the physical characteristics of the fabric are extremely important. Furthermore, the chemical conditions involved must also be taken into careful consideration in the selection of a fabric for a given application. Nylon, with its exceptional physical properties is a man-made fiber that possesses outstanding advantages for many filtration uses. AIthough the initial cost of nylon filter cloths is relatively high compared t o that of cotton materials, the over-all costs, including the operating economies obtained by their adoption, may be considerably lower, This is particularly true when the nylon fabric is used under such conditions of operation that other properties of the fiber are utilized to advantage-for example, the factors of heat resistance and chemical resistance. I n many instances a lighter weight nylon fabric can be used which may offset in part the higher pound cost of this man-made fiber over cotton. The smooth surface of filament yarn constructions is also an advantage in some uses. For example, in the ceramics industry filament nylon fabrics have proved very successful for clay processing. The filter cake tends to drop away from the cloth when the presses are opened, resulting in lower operating costs as well as longer cloth life because of the elimination of drastic scraping operations. In view of the diverse chemical conditions encountered in filtration, there is a need for various types of filter media. Many operations are conducted under strongly acidic or caustic conditions requiring chemically resistant fibers. The acrylic type fibers such as Orlon, dynel, and Acrilan have outstanding chemi-
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(:a1 resistance, particularly to acids. As each fiber possesses its own unique chemical characteristics, it is neressary to take into account the particular chemical conditions involved in the selection of a filter cloth. It is usually necessary to evaluate various types of fabric under actual operating conditions to determine the most economical filter media for a given process.
Canvas-Based Plastic Laminates Are Generally Used for Gear Stock Shown here are the impregnated stock and a gear machined from this stock
Generally speaking, the other types of filtration equipment do not require the heavier fabrics used in conjunction with filter
presses. For example, in rotary drum vacuum type fiItem a relatively lightweight, finely woven fabric may be used. However, it is important that a filter cloth have the correct porosity to per mit optimum cake build-up during the filtering cycle. As this ia a continuous operation, effective cake discharge is essential for efficient operation. Here again, fabrics of man-made fibers can be used to advantage. Monofilament fibers, such as saran, which also possesses exceptionally high chemical resistance, are employed for critical filtering operations as well a8 screening applications. The use of a monofilament yarn with rodlike characteristics precludes the possibility of particle build-up within the yarn structures, thereby reducing the tendency of the fabric to become clogged during use. A similar result may be obtained with a tightly twisted continuous multifilament yarn construction. Electroplating operations are usually conducted under acid or alkaline conditions. Accordingly, the use of chemically resistant fibers, such as Orlon and dyncl, can be employed to definite advantage in many applications requiring anode baga. The bags surrounding the anodes collect any particles which may drop from the anode, thereby maintaining clarity of the chemical solution, necessary for optimum plating conditions. Similarly, in the operation of electrolytic cells utilized in metallurgical processes, B separating medium may be required. Obviously it is necessary that any fabric selected as a diaphragm material be resistant to the chemical conditions involved for effective continuous opera-
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tion. A man-made fiber, which has been used to advantage in this type of application, is Orlon, which is highly resistant to strongly acid solutions a t elevated temperatures. Laundries, Still another important field for industrial textiles is the laundry industry. Laundry nets are used for segregation of wash loads. These nets are subjected to a great deal of mechanical abuse in the laundry. Accordingly, nets formed from string cords are required to attain economical net life. Because of the high degree of economical net life, the development of continuous filament nylon Ieno weave constructions has enabled the laundry net manufacturer to employ lighter weight fabrics than used heretofore. As they possess the high degree of strength necessary to resist snagging and other forms of mechanical wear encountered in the laundry, the lighter weight nets have resulted in higher pay loads. Similar nets are used by the hosiery industry for dyeing operations. Here again, the advantages of lighter weight nets are apparent. The use of a fiber such as dynel with low moisture absorption has resulted in dyestuff economies. Another type of laundry application involves the cloth used for covering pressing machinery. A durable fabric possessing adequate heat resistance is necessary for this purpose. Resintreated nylon fabrics of both the continuous filament and spun staple types are being succesbfully used with resulting operating economies. Other Uses. There are many other industrial applications where textiles made from man-made fibers can be used to advantage. It is impossible to cover these in detail a t this time, but mention should be made of the possibilities of these fabrics for outdoor tarpaulins and other types of protective coverings. There are sometimes decided advantages in getting away from the heavy canvas covers which have been necessary in the past for many uses. Lightweight rubberized or resin-coated continuous filament yarn fabrics possess the tensile strength of considerably heavier and bulkier cotton fabrics. They also are resistant to mildewing and can be stored under wet conditions. Fabric8 made from man-made staple fibers, such as nylon and dynel, also have excellent physical characteristics for certain applications. However, there are problems of waterproofing which must be solved before they can be generally used for outdoor purposes. The man-made fibers that are commercially available today provide the textile technologist with new basic materials for improved industrial fabrics. As there is no one universal metal, EO there is no one all-purpose textile fiber. It is the job of the technologists to determine the best possible fabric for a given industrial application. With a thorough knowledge of the fundamental properties and Characteristics of the available fibers, whether they be natural or man-made, the fabric engineer can, by careful study of the particular end-use requirements, design suitable fabrics for evaluation. However, only by extended tests, generally conducted over a long period of time, can the best fabric be determined, To complicate matters, the prices of textile fibers are always subject to change. Furthermore, improvements are constantly being made in the properties of existing fibers, and new man-made fibers are in the test tube stage. I n any event, it can be safely said that new and improved industrial textiles are here today and more can be expected in the future. This continuing development is due in very large part to the work and achievements of the producers of man-made fibers. RECEIVED for review March 31, 1962.
ACCEPTED July 3, 1952
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