SYNTHETIC FIBER ing of acetate with Dacron provi be of practical utility in raising the burn index. SUMMARY
Table V summarizes some of the contributions that the synthetic fibers, wool, and rayon are expected to make in fabrics containing blends of these fibers. The data are considered preliminary. Further textile research upon blending is in progress to confirm and t o elaborate the results. It is indicated t h a t blending the techniques may employ the synthetic fibers with wool and rayon t o increase strength, resistance to abrasion, dimensional stability, recovery from wrinkling, and retention of press, while wool and rayon may be employed with the synthetic fibers to modify pilling and burning by embers. The blending of wool with some of the synthetic fibers to augment crease recovery is also indicated. The contributions of the synthetic fibers to rayon and wool and vice versa indicate t h a t the two groups of fibers are complementary to each other and t h a t fabrics possessing maximum functionality can be produced from blends of fibers from these diverse groups.
50
x
E 40 -z z
a 3 m 30
20
LITERATURE CITED 100 %
50/50
RAYON,
100“!3
”
ACETATE,
o AC R o N
OR WOOL
Figure 14. Hole Burning of Blends of Wool, Acetate, or Rayon with Dacron Polyester Fiber 6-ounce-per-square-yard tropicals
(1) von Bergen and Clutz, Textile Research, 20,580 (1950). (2) Beste, L. F.,and Hoffman, R. M., Ihid., 20,441 (1950). (3)Ibid., 21, 66 (1951). (4) Carothers, W.H., and Hill, Julian, paper presented a t 82nd Meeting, AM. CHEM.SOC.,Buffalo, N. Y.,1930. (5) Collins, G.E.,J. TextileInst., 30,46 (1939). and Leach, L. L., Ihid., in press. (6) Dennison, R. W., (7) Hamburger, W. J., Textile Research J,,15, 169 (1945); Rayon Textile Monthly, 26, 341 (1945). (8) Hees, W., Melliand Textilber., 32, 215 (1951). (9) Morehead, F.F.,Textile Research J.,17,96 (1947). (10) Ott, Emil, “Cellulose and Cellulose Derivatives,” p. 412, New York, Interscience Publishers, Inc., 1943. (11)Peckham, S. C.,and Largen, E. H., unpublished reports; U. S. Patent 2,595,977(1952). (12)Rath, H., Melliand Textilber., 20, 497 (1939). (13) Reumuth, H., “Textile Microscopy in Germany,” Textile Ser., Rept. 13 (1947). (14) T.I.I.C., “German Synthetic Fiber Developments,” p. 944,New York, Textile Research Institute, 1946. (15) Time (Sept. 14, 1931). (16) Traill, David, J. Textile Innst., 42,221 (1950).
ture with one zero removed is the burn index plotted in Figure 14. Since the formation of holes is not only a function of the surface temperature of the heated particle but also of its heat capacity and time of contact, a series of subjective tests was made. A burn index of 45 to 48 by this technique was found t o be satisfactory. The burn index of wool was found t o be 52 to 53. Figure 14 illustrates t h a t less than 20% of rayon raises the resistc ance of blends with Dacron to the level of wool, and 50-50 Dacron-wool fabrics have a n acceptable burn index. The blend-
RECEIVED for review May 20, 1952.
HAROLD HAUGAN, Bell Aircraft Corp. : I would like to have a comparison made of the flame-retarding characteristics of syn-
fire resistant of all fibers, with the exception of glass, asbestos, and saran. It is even more fire resistant than wool.
thetic fibers. J. B. QUIG: The flammability of Orlon is between that of viscose rayon and acetate rayon. The flammability of nylon and Dacron are essentially the same. Nylon and Dacron, like all fibers, are affected by the type of finish, and so these answers are for the fiber without any finish. I place Acrilan in the same class with Orlon, and X-51 also is in this category. T h a t leaves dynel, and I a m going to ask Mr. Setterstrom to comment on the flammability of dynel. C. A. SETTERSTROM : Dynel, as far as we know, is the most September 1952
ACCEPTED June 17, 1952.
A. R. ROBBINS, Stein Hall & Co., Inc.: Would anyone care to estimate what proportion of the acrylic fibers and Acrilan would be used alone, that is, without blending, particularly in woven fabrics? J. B. QUIG : We would like to know the same thing.
S. B. McFAmAND, Celanese Corp. of America: Although this question may not have an answer judging from what Dr. Quig has said, nevertheless I would like to ask Dr. von Bergen:
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In view of the hydrophobic nature of wool, how do you account for this nonwicking business? W. VON BERGEN : As you know, from the curve of the moisture absorbed, wool can absorb a t 1007, relative humidity betneen 30 and 357, water. It holds that water before it freezes, whereas in the newer synthetics the water is picked up and stays in its liquid form. T h a t is the explanation we have for the wicking. C. A. SETTERSTROM : I would like to ask Dr. Dillon to add his comments on that if he would. J. H. DILLON : I should like to add just one other thing to Dr. van Bergen’s correct explanation, that is, that wicking is just a matter of surface wetting. It is just a matter of contact angle, and apparently while there is high absorption in n~ool,the water does not tend to spread over the surface. A. H. McCULLOUGH, Rayon and Synthetic Textile Co.: I am very interested in the possibility of extending the markets for viscose. I believe Dr. Fitzgerald said something about applying the X-2 process to blends of cotton and rayon. I wonder if he would tell us a little more about what percentage of blends and whether it will stabilize both yarns to the same degree. L. K. FITZGERALD : We have become very much interested in our plants in blends of cotton and viscose, particularly as they ma? be tieated with X-2 chemical, because as far as me know, any procrss that is available to date t h a t furnishes increaPed resilience, increased wrinkle resistance, and increased dimensional stability, by virtue of a cross linking of the molecular structure of the fibers, tends to embrittle those fibers certainly to some degree. This X-2 processing contributes far less to embrittlernent than the normal urea formaldehyde or melamine formaldehyde finishing processes. Frankly , me do not know ’i? hat percentages of viscose to cotton should be used for optimum results. JuQtas LTr. Bouvet said yesterday, the percentages of those blends depend heavily upoii what end results you are trying to acquire. The blends that we have run as of today have been largely 50-50 blends, both in warp and in filling. I think they could probably as well have been 40 -60 blends or 60-40 blends. Other fabrics have been made n i t h all-cotton n-arp and n i t h allspun or filament viscose in the filling CHARLES FOWLER, U. S. Rubber Co. : One of the biggest gimmicks that’s being sold to the consumer today is the quiclrdrying propel t y of the new synthetics I would like to ask if the comparative tests made to date have been made on yarns only or on fabrics too, and if on fabrics, what is the effect of fabric construction on that quick-drying property? J. B. QUIG : The tests have been run on fabrics, and fabric construction is a factor in the time of drying. The more open the fabric, the quicker the drying. I think it is probably understood by everybody that there is a difference in the time of drying of the spun yarns versus the continuous filament yarn and that is a very important thing to remember. The greater number of points of contact nith the spun yarns causes gi eater capillarity and sloTver drying. R. W. SIMPSON, Janesville Cotton: I riotice that the acetate rayon was relatively low in crease resistance. Can crease resistance be improved by finishing methods similar to those used for viscose and cotton? A. M. TENNEY : Any additional resin of the right type will increase the winklc recovery and in some cases the wrinkle resistance of an acetate. However, apparently that is less in the acetate than it is in the viscose, possibly because the acetate starts with quite a resistance to wrinkling based on its high modulus-in the range of 3%. Usually in the spun fabrics the working range of manufacture allows you to keep well within the first elastic range under the modulus, which I call the low load stretch, and in that range I believe that the acetate, like q-oo1, has a strong resistance to wrinkling. 2 184
R. I. REIS, D u Pont Co.: Does this finish that you speak of, Mr. Fitzgerald, make possible a 100% rayon, launderable shirt? L. K. FITZGERALD: JVe could talk a t some length about what is washable and what is not. You see, we grew up in a cotton plant and when we say “washable,” we mean just washing. We don’t mean in lukewarm water or suds or that it be by hand, just so very carefully. We mean boil it and use a littlr caustic or some Chlorox if you v a n t to. We certainly do not rccommend the use of Chlorox on fabrics generally. I Rill give you bome examples of what we have been able to do. We have made garments of vat yarn-dyed all-spun viscose in plain weaves. We have sent them to the commercial laundries and had them washed 20 times over with white sheets thinking that was about as vigorous a washing as we would normally meet, As far as we could see there was no appreciable deterioration of the fabric. Dimensional stability from the start to the finish of the 20 commercial sheeting Iaunderings was in the order of 11/4% shrinkage. We have washed these same fabrics up.ivards of 40 times in an ordinary home washing machine and the fabric was still a good fabric. For me to say flatly that rayon so processed becomes a b ITashablc as cotton I think would be stretching it a bit, though we have no definite evidrnce to thr contraiy. R. M. HOFFMAN, Du Pont Co.: This question is directed to Mr. Goldberg and has to do with what I think is some confusion, certainly on my part, bet8xeenhydrophobicity and pickup. I n my lifetime I have bought a rubber raincoat because it had a low pickup and a low regain, and a bath sponge because it had again a low regain (probably below 106) but a high pickup. At the present’ time on my desk there is a sort of a novelty, a blotter Tvith a high pickup, and the novelty lies in the fact it is made out of spun-glass fibers. Mr. Goldberg, in the uses in which you predict hydrophobicity will be a disadvantage, do you mean low regain or low pickup? J. B. GOLDBERG: I do not know that we can divorce the two. I understand your point, but as you know a great deal of emphasis has been put on the low pickup of some of the newer synthetic fibers, and as has been mentioned before, the construction of the fabric of course has a great deal to do with that. As a mat,ter of fact, m y personal opinion is that in fabrics made of hydrophobic fibers, if the construction is such that the moisture pickup between the fibers is good, presuming that we are talking about fabrics that are \Torn next to the body, they are likely to feel more comfortable. The fibers themselves are hydrophobic but the fabrics can be hydrophyllic. Moisture can be absorbed or retained betm-een the individual filaments. I spoke of hydrophobia of fibers as being possibly undesirable. I was referring to the fibers and not to fabrics made from the fibers. Kow, on the other hand, if you have fibers that are hydrophyllic, naturally the construction of the fabric becomes less import,ant, because if the fibers themselves pick up t8hemoisture, the net effect as far as the skin comfort is concerned is likely to be pretty much the same.
C. A. SETTERSTROM: Mr. Kilborne, what is the effect of ultraviolet exposure on the tensile properties of silk? W. S. KILBORNE : Cltraviolct exposure affects silk pretty much in relation to the fabric that you have originally crcated. If you want a fabric that is washable, you would have t o sacrifice some fastness in the coloring. A prolonged period of intense exposure to sunlight will degrade the silk fiber. HARRY JEFFERIS, Daily h’ews Record: I would like to ask Mr. Kilborne a t the time the chemical industry accepts his invitation to go to work on silk: Where does he think they should begin in order to benefit the silk industry most and find the quickest profit for themselves?
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W. S. KILBORNE : I think t h a t the most logical starting point would be in getting better dyestuffs and better finishes of more permanent nature so t h a t silk could be a truly washable fabric. Silk has been in the picture for 4000 years and I think t h a t actually there has been very little done on it as an industry in the last few years. As a starting point, in washability I think there is a n area that could be developed into a sizable business, Also, the chemical industry has been working on these new fibers which seem t o involve an initial capital outlay of somewhere around $70,000,000, while it would not be necessary t o have t h a t outlay or anything like it to go to work to make silk a very outstanding fiber. A. H. McCULLOUGH: If the industry did accept the invitation, what are the economic possibilities? What does the silk association feel is the total production of silk that can be attained in the United States or throughout the world? W. S. KILBORNE : During tho war the productive capacity in Japan was pretty well desolate. Japan today is producing for the entire world just a little over 200,000 bales. They are on a 5-year program where they hope to get it up t o 300,000 bales per year. We used to use in this country alone 600,000 a year. China today is out of the picture because all the silk grown in China is now in control of the Communists. T o really develop and expand the market for silk or rather the resources for silk, we would’have to take advantage of the fact that it can be grown in temperate climates. There is a certain amount that is grown and if we could develop a method of producing effectively a silk fiber from the fiber gut and spinning it, then i t might be economical to raise it in this country. There is a very wide area in which to operate, supposedly in California, where there is thought t o be the ideal climate for raising mulberry trees and silk worms. S. B. SWERDLOFF, Celanese Gorp. of America: Yesterday Dr. Dillon showed us some stress-strain curves on regenerated silk, and today we have been talking about regenerated silk. Is there enough known about the properties of regenerated silk to tell us something about how they might compare with the natural fiber? J. H. DILLON : Regenerated silk is a scientifically interesting subject, but it is not particularly interesting from a n economic viewpoint as far as I can learn. A lot of attempts to make regenerated silk have occurred, particularly in Germany and of course in Japan, and they have come up to about 80% of the wet tenacity of good filament silk. However, in the days when most of these chemical experiments were going on they did not bother t o plot the whole stress-strain curve, and there was a bit of overenthusiasm shown by some of the authors of papers on regeneration of silk. It might be explained by a lack of knowledge of modern statistics. It is very interesting though and I was very much interested in Mr. Kilborne’s presentation because we gave some thought to going back and seeing just how good a regenerated fiber you could make. The trouble occurs when the scientists run into an economic block like the silk problem, where the main cost in making raw silk is up through the process of growing the cocoon. That is over SO%, I believe, of the cost of the raw silk. Now, you see your regenerating process will start from the cocoon. You cut out the chrysalis, put it in solution, and spin the yarn, and you have 50% of your cost t h a t you cannot do anything about. Then, of course, you have the other block in any of these countries where silk a t one time was profitable to grow. As the economic conditions of the country improve and as the living standard of the people improves, it becomes less and less of an inducement to raise silk, and that is what is happening in Italy and France today, and Japan is rapidly going that way. As long as the United States is pouring out funds all over the world t o raise the standards of these people, we are making i t less and less possible for the “queen” to reign except in a nominal way September 1952
question of the accumulation of static charges on fabric made from the synthetic fibers, it has been pointed out t h a t some of the acrylic-type fibers are produced and sold with a static agent already on it. In what direction is the best effort to be expended on static or the elimination of static? Is it toward the finishes, antistatic finishes or have we a better possibility in blending fibers which complement each other as to static? What of the use of Vicara or natural fibers which can pick up enough moisture to dispel the static? What is the general prospect of how to accomplish this static business? J. B. QUIG: We believe that the best research effort will be expended by directing the work toward the development of permanent antistatic materials. The objective will be t o diminish the development of static electricity by the incorporation of a permanent antistatic material in the fiber or fabric. Blending fibers from positive and negative regions of the triboelectric series has not given a universally satisfactory answer, since the minimum static charge varies with the reference materiali.e., human skin, rubber, steel, etc. The moisture regain of a fiber has a n important effect on static accumulation as moisture will serve t o dissipate the charge. Therefore, the blending of Vicara, wool, and other hydrophilic fibers with the new synthetics is beneficial. The solution of the problem in 100% synthetic fiber fabrics appears t o depend on the permanent antistatic approach. C. A. SETTERSTROM : We think that we have developed a semipermanent antistatic t h a t will stay on a blanket for its wash life. We are just making replicate mill applications now and it is still a hope rather than a promise. The problem with blankets is not so bad, because a blanket in its lifetime may be washed only once or twice a year. Fifteen, 20, or 30 washes, and not too vigorous ones, probably extend over the life of a blanket. With men’s hose, however, we have a problem of a different order of magnitude. There we need a finish t h a t will withstand maybe 50 vigorous launderings, especially for these new fibers t h a t are so easily washable and where the important sales claim is easy home or easy commercial launderability.
R. W. SIMPSON: Would anyone care to comment on the economic properties of the Japanese polyvinyl alcohol fiber? C. A. SETTERSTROM : The Japanese polyvinyl alcohol fiber is cross linked with formaldehyde in order to make it more water insoluble, and it is my inexpert opinion that when you are through with the fiber formation, cross linking, and insolubilization, you have a cost picture that is not particularly favorable in view of the long-time advantages of some of the American fibers t h a t are now under development.
A. H. McCULLOUGH: I would like t o get Dr. Dillon up for just a moment again on this economic problem of silk. Is not that economic problem working on both wool and cotton? I would like to hear the comments about the increased population in the temperate zone where we raise our sheep, cotton, and silkworm. Will not that play a big part in the battle of fibers in the fact of future market supply? J. H. DILLON : I think there is something in that, but I think that the changes in consumption of various fibers can be popitive and negative based on these progressive changes in civilization. For example, I think you can say that one reason the consumption of wool went up not lo i g ago was because of a change in the standard of living in this country-high wages, etc. People who had not bought fine worsted suits before were buying most of them; the farmer was better off too. He now has more than the one blue serge suit that he used to wear for 5 years and t h a t sort of thing. I think it is too complicated to make any simple statements about it. T h a t is all I can get out of it because I am not an economist.
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W. VON BERGEN : That is one thing that worries us in the wool industry. Definitely the percentage of wool in the world production of all fibers is dropping. I n the year 1900 actually one fifth of all fibers used in apparel industry was wool. This percentage has dropped in 1950 to only 13%, even though woo1 has increased in poundage SOY0 in these 50 years-from 1,600,000,000 to 2,400,000,000 pounds. What makes it difficult is that the grazing areas in the world suitable for the breeding of sheep are definitely limited, and we cannot, like the chemical industry, just pour millions of dollars in and synthesize sheep. In this country the grazing area in the last 10 years has been cut down considerably because of the policies by our Government to preserve the national parks out West. I t is claimed that sheep are detrimental, though I think this has been exaggerated, but they have reduced the percentage of sheep allowed in national forests by a t least 50%. That is probably a major reason why the wool production in this country has gone back from over 450,000,000 pounds to about 200,000,000 pounds.
L. R. LITTLETON, United States Army: Which one or ones of these newer synthetic products appear likely to replace silk in cartridge cloths? J. B. QUIG: I am not certain of the answer to this question. Orlon has been tried in these cartridge bags and the military has said t h a t they behaved well. I think i t was last spring we heard they were going t o make procurements of Orlon for cartridge bags, but I don’t know what the situation is. A. M. TENNEY: l l y suggestion on this is froin ancient history. During the first warld war we went through the saine problem and I happened to be one of those who worked out a cartridge bag cloth as a substitute for silk from mohair. The protein seems to keep the ember from continuing to burn and prevents flashback in the rifles. I wonder if Vicara might not have some possibility for t h a t use simply because of its protein nature. J. V. N. DORR, Dorr Go., Inc.: We have very often heard the statement that 15y0rayon staple fiber added t o cotton works very well and has been found more economical. Mr. Fitzgerald, why do not all cottons today contain 15% rayon in their blends? L. K. FITZGERALD: I am not sure I know why it has not been done. I can give you some of the physical facts. Just as Mr. Bouvet said yesterday, you do not always get precisely the characteristics from blending fibers that you might expect. Normally in blending, please understand that the end results will be considerably affected by such things as denier, staple length, and so on. The addition of 15% viscose staple to a cotton yarn does not appreciably change the breaking strength of that yarn in either the dry or the wet state. As you begin to go above that point, you begin t o come down below the breaking strength of cotton, and as you continue to add more and more viscose up to lOO7, viscose, then t h a t breaking strength could go back up
again. Assuming that me were to start with a break factor in a cotton yarn of around 2100 pounds, you would see very little change in it with the addition of 15y0viscose. If we were to go to 507, viscose that break factor TTould come down to somewhere around 175, perhaps 180, which is still a practical yarn for apparel. We agree entirely with your thinking. Certainly a t present with viscose a t a lower cost than cotton, viscose can very well in certain of those low percentages be added generally to all cotton fabrics almost without exception. K e have in the process of manufacture about 50 different fabrics that are blends of cotton and viscose, and we expect them t o be commercially produced in very substantial yardages. J. B. GOLDBERG: I am not sure that adding a small percentage of viscose to cotton is not necemarily enhancing it unless you specify what properties you arr seeking. One thing I think is important and which may possibly be a handicap is the finishing of the blended fabric. In all cotton fabrics you normally are obliged to go through pretty rugged scouring and bleaching operations, and with the introduction of viscose rayon in such blends, you are imposing restrictions on the manner in which you can handle those cotton fabrics.
J. V. N. DORR: To come bark to the same question. In other words, if the cotton manufacturers find there is some economy in considering the difference on the two raw materials, there is no logical reason why he should not go ahead. J. B. GOLDBERG : You are quite right about that. We feel that if not today, certainly some day we can produce cottonrayon blends or all rayons that will be cheaper than cottons. There is not much question about that a t all. The point is you must specify what end uses those fabrics are going into because viscose rayon in some cases would enhance the cotton and in many other cases would limit its use. The cost of the fabric itself is not the sole criterion of its usefulness. G. K. LAKE: I just read of some work that we did in sheets some time ago. They were 507, rayon, which is fairly high The public did not like the idea. They felt that rayon was not as substantial as cotton was. T h a t was probably why it flopped, but one of the things t h a t may be interesting is that we could not g r t as good a white. We never found out exactly why, but the fact remains that when we tried to run those sheets through a continuous peroxide bleach, apparently the peroxide jumped for the rayon and forgot the cotton, and the result was that we got a rather gray-looking sheet as coinpared to the good white one we were getting on cotton. That is one disadvantage. C. A. SETTERSTROM : Is there another question? If not, I want to express the appreciation of the marketing subdivision of the Industrial and Engineering Division to the speakers who have presented a uniformly high level of papers: we have had a series of exceptionally thoughtful and stimulating papers. Thanks to you in the audience for your intelligent qucstions and closc attention.
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