C&EN A N N U A L REVIEW OF ι / i Developments m the Chemical and Process industries * • • ' I

TEXTILE INDUSTRY CHANGES PACE ROBERT E. W R I G H T and M I L T O N K A R R I S , Harris Research Laboratories, Washington 77, D. C

The comparatively s'ow, evolutionary type of change to which the texti le

industry has been accustomed is giving w a y to a faster rate of advance . . ·

. . . A rate resembling, in some instances, a revolutionary upheaval. The accelera­tion is caused primarily by pressures from two sources: the backlog of new products and processes developed during the past few years, and the economic pressure of declining markets which stimulates the search for novelty, improved quality, and reduction in costs.

Among the most dramatic of these changes, and one which shows clearly the impact of chemical research and tech­nology on the textile industry, is the trend toward modification or displacement of established fibers from their traditional assignments. Already the consumer has seen evidences of this in the industrial field where, for example, rayon and nylon tire cords and Vinyon filter cloths are now well established; in domestic applications, where some of the newest synthetic fibers are finding employment in diaperies and upholstering materials; and in apparel fabrics, where rayon and nylon are gain­ing increasing markets in shirting-type fabrics, and rayon is challenging wool in the summer suiting field.

in many instances acceptance of the man-made fiber as a competitor of the natural product has had to await further chemical modification or the development of special treatments such as resin fin­ishes. However, advances in the tech­nology of chemical modification and fin­ishing have also served the natural fibers, as witnessed by the increasing use of resin finishes on cotton to improve crease re­sistance and drape and to impart other special effects; by the already widespread employment of shrinkage control proc­esses for wool; and by the interest in chemically modified wool of enhanced resistance to chemical attack, which i s finding applications in the reclaimed wool industry to protect the fiber from damage during stripping.

Cellulosic Fibers Several contributions have been made

in the field of chemical modification of cellulosic fibers. Improvements in di­mensional stability, hand, crease resistance, and moisture relations of viscose rayon which result from resin treatments have been shown to stem in some instances

from cross-linking effects. One new urea-formaldehyde resin provides creaseproof-ing and dimensional stabilization without the disadvantage of high chlorine reten­tion that characterized some earlier com­pounds. Three techniques for synthesizing disulfide cross links in cellulose deriva­tives and polyvinyl alcohol have been in­vestigated; laboratory products were ob­tained by the Bunte salt method, by the synthesis of mercaptans from thiourea fol­lowed by decomposition of the intermedi­ate isothiourea and oxidation to the di­sulfide, and by the replacement of tosyloxy groups with disulfide links on reaction with sodium thiosulfate followed by mild oxidation. A process for incorporating amino groups into cellulose introduces about 0.6% of nitrogen by treating a cellulosic fabric with an aqueous solution containing sodium hydroxide and 2-amino-ethylsulfuric acid, followed by heating; the modification makes possible the dye­ing of cellulosic materials in strong, fast

shades by acid wool dyes. A method for the partial acetylation of cellulose by kctene utilizes purified cotton linters which îire first swollen in water and then solvent-dehydrated before the treatment. Car-boxymethyl groups introduced into cotton by treatment with alkali and chloroacetic acid have been found to increase the rate of moisture sorption and the total water absorbency. Methanolysis of cotton cellu­lose in the presence of anhydrous acid yields, a new type of short-chain cellulose molecule which is resistant to further action of strong alkalies.

A number of workers are investigating methods for improving such properties of cellulosic materials as flame resistance and resistance to attack by various biological and chemical agents. An Army Quarter­master Corps project at Columbia Uni­versity, for the study of fundamental principles of flameproofing, is expected t o devote a considerable portion of the effort to cotton and rayon. A new durable

Milton Harris

TL/ξ ILTON HARRIS has been active in textile chem-istry since obtaining his Ph.D. in protein

chemistry from Yale in 1929, when h e began in­dustrial research on silk with Cheney Bros. In 1931 he became research associate in the Na­tional Bureau of Standards, in 1933 director of research of the Textile Foundation, and in 1945 established the Harris Research Laboratories in Washington. Two years ago he was voted one of the 10 outstanding cellulose chemists in the TJ. S. by the Chicago Section of ACS. He i s the author of approximately 100 papers on wool, silk, and other textile ma­terials, as well as numerous patents.

"D OBERT E. WRIGHT is a researeh associate and librarian at Harris Research Laboratories in

Washington, D . C , and also serves as assistant edi­tor of Natural and Synthetic Fibers Abstract Serv­ice. H e attended the College of Wooster and the University of Illinois Library School, and his peculiar fitness for his position is probably due to the fact that he is chiefly interested in chemical literature that pertains to textiles and textile finishes. He bas about 10 published papers to his credit, mostly on textiles and synthetic fibers. Dur­ing the war be was chief, Training Intelligence, USAAF Training Command. Robert E . Wright

38 C H E M I C A L A N D E N G I N E E R I N G N E W S

tiameproofing treatment is applied by sub­jecting the fabric to a bath consisting of a solution of titanium and antimony salts. The mechanisms involved in atmospheric degradation of cotton textiles have been investigated and various combinations of photochemical and oxidative reactions are considered as causative agents. One study has shown that deposition of 0.5 to 1.3% of manganese on tentage fabric is ef­fective in retarding photochemical deg­radation. On the microbiological front it has been shown that mildew resistance is conferred on cellulose derivatives by chemical substituents in the proper posi­tion and number and does not depend on the nature of the derivative; thus, in order to impart mildew resistance to cotton, it is necessary that all anhydroglucose units in the surface fiber be substituted, one substituent per anhydroglucose unit.

Wool Research is continuing in the explora­

tion of mechanisms involved in various physicochemical relations; lithium bro­mide, a powerful hydrogen bond breaker, has been used to effect supercontraction and permanent set without severing co-valent linkages. This indicates the im­portance of hydrogen bonds in these phenomena. The effects of treatment with such agents as /S-propiolactone on me­chanical properties are being investigated, while the enhanced chemical resistance afforded by the use of ethylene dibromide to rebuild stable cross links is finding commercial application. Contributions have also been made to the technique of determining damage in wool, primarily through modifications to the alkali-solu­bility test. Work is going forward on the determination of the chemical constitution of keratin and the molecular weight of protein material extracted from wool fibers.

In the area of wool shrinkage control, studies have been made of the inhibitory effects on felting of cross linking with di-epoxy compounds and the formation of organosilicon polymers in situ. Continu­ing studies are being made of the nature of the action of such agents as permanga­nate solutions and sulfuryl chloride and of the relation between disulfide bonds and felting properties. Recently patented shrink-resistant treatments have described a continuous rapid chlorination process and applications of chloroprene and buta­diene polymers; the first of these is being applied commercially, as is a new mela-mine resin which can b e applied at low temperatures and does not require a high-temperature cure. The extent of com­mercial acceptance of antifelting treat­ments is indicated by the fact that an estimated 95% of current wool sock pro­duction is treated for shrink resistance, and that increasing use is being made of shrinkage-control processes in such appli­cations as shirts, blankets, sweaters, knit­ting yarns, and other items.

Considerable activity is apparent in A e field of wool scouring, where the effects of such variables as bath temperature and

nature and concentration of detergent have been investigated. Interest in syn­thetic detergents for scouring remains high; a low-temperature method for piece-goods scouring employing a synthetic is described, and laboratory techniques for evaluation of detergency have been de­veloped.

New Fibers Considerable improvement has been ef­

fected in the properties of several of the newer man-made fibers. Current produc­tion of Vicara, the zein fiber introduced in 1948, is characterized by increased tenacity and enhanced resistance to chemi­cal attack. A new heat-stabilizing proc­ess is capable of preshrinking polyethylene fabrics to less than 2 % residual shrinkage at temperatures up to 165 e F., and poly­ethylene filaments are now being manu­factured by three companies. Improved water-repellent finishes are being obtained on nylon with a new silicone padded on from a dilute water-in-oil emulsion.

Orion, the polyacrylonitrile filament, has been improved in regard to its dyeing characteristics. Although initially manu­factured only in continuous filament form, development is now under way for produc­tion of Orion staple, which is expected to find a place in a number of apparel fabrics by virtue of its high bulking power, wool-like hand, resistance to wrinkling, and launderability. Interest in the pro­duction of this type of hydrophobic fiber in staple form is indicated by the intro­duction of dynel, an acrylonitrile-vinyl chloride copolymer manufactured in staple lengths. Dynel is related to Vinyon N, which has been appearing in drapery fabrics and in men's socks and tricot underwear, as well as in a number of industrial applications.

The investigation of synthetic poly­peptides has noved into the industrial laboratory within the past few years. Fibers have been formed from polymers and copolymers of simple amino acids, and the molecular structure of such mate­rials has been studied by x-ray and infra­red measurements. Fibers with structures similar to those of a- and /3-keratin have been prepared.

Celcos, first announced during 1949, is described as combining some of the prop­erties of both viscose and *cetate rayon; it is believed to be a partially saponified cellulose acetate. Other new fibers, still in the laboratory stage, are a cottonseed protein product and a water-soluble sodium carboxymethylcellulose fiber. Cas-len, a new casein monofilament, is seeing service in curled form in filters and as a substitute for hair in mattresses and upholstery.

Dyeing Various high-temperature dyeing proc­

esses are claiming attention, one of the most interesting being the Thermosol process for dyeing nylon, Orion, and fiber V. The selected dye solution or disper­sion is padded on the material and then dried and heated to 360° to 4 8 0 e F. for a

short time; the dye appears to dissolve in the fiber, which has been swelled with urea or some other swelling agent. High-temperature methods for the dyeing of wool and other fibers are also being investi­gated in an effort to develop satisfactory continuous dyeing techniques, in contrast to present batch methods.

Commercial runs of acetate fabrics in vat colors have recently been made by a process employing photosensitive mate­rials and special catalysts; color develop­ment is effected by irradiation. Anthra-quinone Blue SA, an acid wool dye, has been tagged with radioactive sulfur and will be used to study the course of sorp­tion of dye molecules by fibers.

In addition to the Thermosol process, a number of other techniques are being investigated for dyeing the new hydro­phobic fibers. Among the most promis­ing is the swelling of the fiber with steam under pressure, coupled with the use of dyebath assistants. Almost com­plete removal of dye from nylon has been found possible by treating the fiber in a bath containing acetic acid, zinc sulfoxyl-ate formaldehyde, and a synthetic deter­gent, and then stripping in a sodium chlorite bath.

Blending for Comfort Although the blending of fibers is by

no means a new development in the textile industry, until recently primary consideration was given to the effects of blending on spinning and dyeing char­acteristics. The long-acclaimed "era of engineered textiles" has in the past suf­fered from confinement to a relatively limited range of available fiber properties. With the advent of such new materials as nylon, Orion, Vinyon N, Vicara, etc., fibers combining such desirable properties as strength, elasticity, softness, or dura­bility are available. That some of these fibers are much less hydrophiiic than most earlier textile materials provides an addi­tional dimension for employment by the textile engineer. Today one of the trends in the industry which gives most promise of a revolution in textiles is the interc st in blending these synthetic fibers with cot­ton, wool, and rayon to provide new standards of comfort in clothing. It is now realized that such physicochemical factors as moisture-sorptive properties and heat of wetting are not only important in designing comfortable apparel but can actually be turned to man's advantage by proper choice of hydrophobic and hydrophiiic constituents in the cloth. Be­fore these possibilities can be. fully realized, more fundamental information must be obtained concerning the mecha­nism of adsorption and release of water vapor, as well as the effect of various mechanical characteristics on the complex psycho-physical sensations associated with the "hand" of fabrics. As answers to some of these questions become available through research currently being con­ducted in a number of laboratories, the transition from evolution to revolution in textiles will have been accomplished.

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