INDUSTRIAL AND ENGINEERING CHEMISTRY
May, 1930
461
The Synthetic-Fiber Industry of America‘ Chas. E. Mullin CLEMSON COLLEGE TEXTILE SCHOOL, CLEMSON COLLEGE, S. C.
e q u a l l y suitable for the manufacture of synthetic yarns and in America only purified cellulose from cotton linters and wood pulp is used. A few other sources are used abroad for rayons of inferior quality. In each process the natural cellulose is well purified b y boiling with sodium hydroxide s o l u t i o n under pressure in closed kiers followed by bleachi n g with sodium I n d u s t r i a l R a y o n C o r p o r a t i o n ’ s P l a n t a t Covington, Va. hypochlorite solution. During the last process it is also beaten iii a hollander to give shorter Nofe-While the term “rayon” was a t one time used collectively t o cover all the synthetic or manufactured cellulosic yarns, it is now mo%toften applied fibers. The purified cellulose is treated by a special process t o the yarns manufactured by the viscose process, although i t is also used as a to bring it into solution or t o render it soluble in certain collective term for the three types of regenerated cellulose yarns, nitro, cupra, solvents. The various methods by which the cellulose is and viscose. The term “synthetic yarn” is applied particularly t o products brought into solution form the major differences in the various made by the acetate process, such as the Celanese brand yarn,, but it is also used t o cover all the manufactured fibers, as in the present paper processes of synthetic-fiber manufacture. In each process this cellulose solution is spun to give the At the present time the United States produces almost as actual filaments, which when collected and twisted together much synthetic yarn as the next three largest producing countries-Italy, England, and Germany-combined. and about form the thread or yarn. I n each of the spinning processes two-thirds of this American production is from plants located the cellulose solution is forced through fine holes, usually in a south of the old Mason and Dixon line. Table I gives the small metal plate called a spinneret, into a liquid or air which world’s rayon and synthetic fiber production for 1929, by the neutralizes or removes the solvent and coagulates or precipivarious processes. Table I1 gives the estimated production in tates the cellulose filaments. In most processes the spinthe United States by various companies for 192!) and 1930. nerets have many fine holes, the exact number varying with Table I11 gives the location of the various plants and variety the number of filaments desired in the yarn, and the filaments from each spinneret are collected and twisted together to of yarn manufactured. form a single thread. In the pot-spinning process, so widely M a n u f a c t u r i n g Processes used in the manufacture of rayon by the viscose process, this twisting proceeds simultaneously with the collecting of the There are four quite different general processes in use for filaments. In the bobbin-spinning process the filaments are the manufacture of the synthetic fibers, and all of these are twisted by a separate and special process after spinning. used in the United States. The above is merely a very brief outline of the general (1) Cellulose nitrate process, used in producing ’fubize yarn. process by which all of these yarns are manufactured, the (2) Cuprammonium process, giving Bemberg yarn. exact details of each process varying widely from those of ( 3 ) Viscose process, used for viscose yarn or rayon. the other processes. The various steps may be summarized Cellulose acetate process, giving Celanese brand yarn. (4) roughly as follows: While these processes resemble each other more or less in a (1) Purification and bleaching of the crude cellulose. general way, they differ quite widely as to the exact details of (2) Solution of the cellulose by various chemical processes. procedure. (3) Aging or ripening of the cellulose solution (viscose procThe same raw material, cellulose, is used in all four proc- ess only). (4) Filtration and de-aeration. esses, and, theoretically a t least, almost any source of cellu( 5 ) Actual spinning of the cellulose solution. lose can be used for this purpose. I n practice it has (6) Twisting together of the individual filaments t o form the been proved that the cellulose from all sources is not yarn.
HE m a n u factureof the synthetic fibers is r a p i d l y becoming one of the most important branches of two major industries in the United States-the chemical and the textile industries. The growth of this industry since the war has been trem e n d o u s , especially during the l a s t few y e a r s , probably exceeding that of a n y other b r a n c h of either of the two m a j o r industries mentioned.
T
1 Received March 7, 1930. Presented before the General Meeting under the auspices of the Division of Industrial and Engineering Chemistry a t the 79th Meeting of the American Chemical Society, Atlanta, Ga , April 7 t o 11, 1930.
(7) Removal of impurities or other undesirable chemicals from the yarn (in all processes except the acetate process). (8) Bleaching, washing, oiling, drying, inspecting, and winding the yarn.
'l'ahle I~.--Esiimated Productrun uf Synthetic X'ihcra by Ceunfries and Processes for 1929 11,
VISCOSB
i:ousrar
Poirnds
Czeebosio.
5omn
.......
a n m u ~ , ~ n n , u n o iou,ui)o ao,oou s~),ooo i1,ooo,noo
Greece ~
~.soo.oun
~o,~on,niin i,8no,ooo
i
i
H~~~~~~ itniy
TUfiiL
sw,oon . . . . . . . . ...... 40,~ao.oou ~i,~+~o,ouosau,oon ....... z.8i3,non 937,000 . . . . . . . . . .
Canada
~
A-mw
Pounds l'armis . . . . . . . . . . . . . . . . . .
8,fiaii.nuir
Austria
CUP.& Pounds
Ac61.%~4
7n.000
......
580,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...................... 8io.000
~2o.ono.ono ~ d
i,sou,ono ....... .................... . . . . . . . . s,son,non
a+I,'ion,ooo i,ooo.oou i8.oun.niio 3,835,000
lapa"
Poland SP'i" Sweden switreiilnd United
states
2.noo.ono
.. 4~0,nuu . . . l2,250,000 . . . . . . . . . . S O ~ . ~ ~ V , O O U7,ooo.oon
-~~ . . . _
~otri Percentage
347.20s.ono
26,007.nno
88.0
0.4
. . . . . . . . . . . .....
a,auu,onn
9.500,ouo
0~0,000
53,soo.noo 3,no.ooo 4,250,000
37,oon,oon 5so.ooo
45,ono,m 20,000,000 fi7o.000
5~~,noo,ooo 18.on0,~ 5.43.5.000
a,oou.oon
420.000
12,250,000
1~3,sao,ooo
15,020,ooo I ~ , ~ ~ O . U404,15~,0nn OO 3.7
3.11
Table Il---Syechefic Fiber Production In the United
1029 Ponndr 82,000,000
COMP*liY
Srsfea
z~,aon,wo
1930 PGEdS 70,000.noo 27,000,000
7,000,000 5,375,000 2,a00,000
10,000,WO 4,000,000
(1,
11,000.wo s,ooo,m
0,500,WO
e,ooo.ono
3,850,000 625.0no 750,000 1,330.000 1.5oo.000 2,000,000
5,000,000 6,500,000 3.250.000
1,500,ooo
2,000,000
mo.m
2,Ow,000
!loo,oO0
1,100.000
1,000.000
2.000.0MI . .
123,130,000
TBbIe 111-Plant
Pounds 3,620,000 S~,OOO,WO
162,330,000
Locstions arid T y ~ o ef Yarns Produced P L A N 7 Locnriolr
COslPAXT
Acme Rayon Corimation Cleveland, Ohio American Bemberg Corpora-
tion
Ameiicen Chhtiilon Corpora-
tion American Enka Corporation American Glinrstaff Corporation Amaskeag Manufacturing COmpanY Uelamose Co",arotio" ceianerc Corporation
Viscose Dissolvers. Industrial Rayon Corporation
Elirabethton, Tenn. Rome. Ga. Asheville, N. C . Eiizabethton, Tenn Manchester. N. H. Rocky Hili, Conn.
Of
AmcriCr
Delawire tion
oaocssof inoisturc, tlie ce1lului;e nitrate isdissolved in a nrixture of ether and alcohol to form the collodion spinning solution. This solntioii is filtered, de-aerated, and forced through fme capillary glans tubes, located in special spinning chambers, into air which evaporates thc solvent, leaving filaments of cellulose nitrate. A iiurriber of these individual filaments arc collected oii a bobbin and twisted together to form the thread. These threads are wound into skeins, which are treated with a sodium hydrosulfide solntion to remove the nitrate groups,
Rayon Corpora-
nu Pont Rryoii Company
~
~
~&rd.~
New Cnslle,
i
i
~
,
1>ri.
Hoffalo, N. Y . Old Hickory. A'. Y . Richmond. Va. Waynesboro, VI,.
Criuueertei City, N. J. Ilasthnmpto", Mass. Clevelnnd, Ohio
couiugton, \,a. niirlington, N. c'. Clifton, AT. 3.
niiriingt"", ,'""Y
Roiland Cornoration Skenandoa R i y m Corpore/*on
Tubize Artificial Silk Company or America viscose company
Woooiocket Rayon Cornprny
N. J.
A e w Hcdford. Miirr.
Psterso", N. 3.
IJiica, N. Y. 1iope,7resi,
vn.
Lewisiow", Pa.
Milrcus Hook, ?.is. Meiidville, Pa.
Parkerrburg. W. VI. Roanoke. Va. Wuonsacket. R . 1.
Cellulose Nitrate Process
I n the cellulose nitrate process the caustic-boiled and bleached cotton linters are nitrated with a mixture of nitric and sulfuric acids to give cellulase nitrate. This is washed in tubs and in the heater, and then boiled to stabilize it by the removal of snlfates, etc. After centrifuging to remove tlie
leaving a regenerated cellulose yarn. The deriitrated yarn is washed, bleached with sodium hypochlorite, soured, washed again, neutralized, soaped or oiled, dried, and inspected. I t is then ready for shipment in skein form or for rewinding into any desired form of package, Nitro silk is manufactured in America only by the Tubise Artificial Silk Company of America. Viscose Rayon
the pnrificd liiiters or wood piilg, iil the form of sheets about 18 inches sqnare, are satisrated with strong caustic soda solution in a suitahle tank with arraiigernents for pressing ont the excess alkali solution. Thesc sheets, oontaining a definite amount of alkaline solution, pass into a shredder, where they are disintegrated into sodacelliilose crnnmbs. Tlie crumbs are placed in sheet-ironcovered cans and aged for a definite lcngtli of time under controlled temperature and humidity conditions. After aging they go to the xanthators or churns, where they react with carbon disnlfide to forrn the desired sodium cellulose xanthate. This xaiitliate is soluble in alkaline solution t.o give the viscose spinning solution. The viscose solution is ripened again, with a close control of time and temperature, filtcred, and de-aerated, when it is ready for spinning. Tlie spinning is effected by forcing this viscose solutioii through another filter, a spinning pump or meter and the spinneret which is immersed in an acid precipitating bath. Spinnerets of small diameter and cont,aining as many fine
It,,les as tile iiumbcr of 6lauients desircd in tlic yimi ure used. ‘rhe acid hat11 neutralizes the alkali ilr the viscose solution a i d regenerates the cellulose filaments. The filaments from each spinneret are collected on a separa.te bobbin or in a rrtpidly r w tating spinning pot. Where the filainents are collected oil a bobbin they are wound parallel ivitliout twisting. but in tlie put-spinning process they receive a twist of about 2.5 turns per inch due to the rotation of the pot. After wasliing and neutralizing the acid present in the yarn, the bobbin-spun filament,^ are rewound onto spools for twisting. The twisted yarn, from either the bobbin- or pot-spinning process, is tlicn desulfurized, nsually by means of a sodium sulfide solution, bleached, washed, oiled, dried, graded, and rewound into packages or packed for shipment. Cuprammonium Process
Cnpra silk is manufactured by a process somewhat different from all the utbcrs in that the damp purified linter cellulose is dissolved directly in a solution of copper hydroxide in strong ammonia, without any previous chemical treatment. This specially prepared cellulose solution is filtered and deaerated. and is tlieii readv for snirmine a t once without either aging or ripening. As in the nrevious DI’OCCSS(?S. this celluloso solution is forced through a s$incret into a suitable coagulat.ing bath. However, in this case the spinneret is larger in diameter, has rather large openings, and the coagulabing solution does not CONIpletely harden the filnnients. As a result the iucompletely coagulated filaments may he stretched by a special arrangement of the spinning apparatus so as to give individual filaments finer than those obtainable by any other proccss in use today. The stretched filainents are finally hardened in a second precipitating bath, and are collected on reels in the form of skeins. This yarn contains considerable precipitated copper, which is dissolved out of the skeins immediately by means of a dilute sulfnric acid solution. It is then washed, neutralized, hleaclied, washed again, soaped or oiled, dried, and sorted. It is finally wound onto spools, twisted, and then rewound onto cones or other packages for use. Most of the cupra yarn is now used for knitting, ete., and very little first-grade yarn is shipped in skein form. Cupra yarn is manufactured in America by &heAmerican 13emberg Corporation. This company is now producing on a commercial scale yarns as fine as 15 deniers with 25 filaments, These filaments are ahout 2.5 times finer than those of natural silk, being only about 0.004 inch in diameter. I t requires about 4225 miles of one of these filaments to weigh a pound. This is by far the finest filament yarn ever produced commercially.
tlic celhilosc ester precipitated by pouring the solution into !I limited voliiine of water. Tlic ester is waslied well with water, the last traces of free acid ncutralized by means of soda, \vashed again, and dried a t a lo^ temperature to tlie desired inoirt.ure conbent. T h i s dried ccllnlose acetate is dissolved in a mixture of scverul organic solvents, of wtiicii acetone is generally the prinv i p s l eonstitimit. This solution is filtered and deaerated, and is then ready for spinning imrnediately without any aging, ripening, or otlier treatment. The cellulose acetate solution is forced through a final filter, spinning pump, and n spinneret of rather large diameter into a tall, narrow spinning chamber containing warm air, which evaporates the solvents present, leaving behind many individual filaments from each spinneret. These filaments are collected, oiled, and twisted in one operation, so as to give a yarn of 2.5 twists per inch without any further treatment. Fine denier yarns with 5 twists per inch are also manufactured. The spinning solvent is, of course, recovered, as well as the escess acctie acid used in the esterification of the r:ellulose. The above process is similar to that used by the Celanese Corporation of America for the manufacture of Celanese h a n d yarn. Advantages of Acefate Process
I t will Ix iiotioed that, wliereas it was necessary in each of ilie previous processes to give the spun yarn a special treatment in the skein form to remove nitrate groups, sulfur, or copper, as the case may be, the Celanese brand yarn is ready for use iinraediately after it is spun, no other wet treatments being necesszry. At the same time this yarn is s o t a regenerated cellulose thread. but is composed of cellulose acetate. Cellulose acetate bears about the same reration to regenerated cellulose that olive oil or ethyl acetate bears to glycerol or ethyl alcohol. No chemist would expect to find the same
Cellulose Acetate Process
The acetate silk, to which the name “synthetic fiber” ur “chemical yarn” has been particularly applied, is manufacdured by n process which resembles that used for the production of nitro silk in tliat the cellulose is esterified in order t u render it soluble in certain volatile organic solvents. This cellulose ester sohiion is then spun into air, a process called “dry spinning.” Mere, however, the similarity between the two processes ends and the acetate process offers many advantages uver the older nitrate process. I n the acetate process the purified cellulose is esterified by means of acetic anhydride in the presence of sulfuric acid, which has a catalytic action, and acetic acid, which acts as a solvent for the cellulosc triacetate formed. When the reaction is complete, water is added to the batch and the t r i a w tate permitted to hydrolyze to about the diacetate. Sodium acetate is added tu neutralize tlie mineral acid present and
Pertion of the Shredding Eqwi ment, Industrial Rayon
colp”l.*Pon
propertias in the ester as in the free alcohol, and we find just as much differencein the properties of the rayons and Celanese brand yarn. The Celanese brand yarn and the regenerated cellulose yarns dye and finish quite differently and in most
otlier respects are quite different. There is no doubt tlint at one time the cellolose acetate process was tlie most expensive of the four methods iii use for the manufacture of synthetic fibers, while the viscose process wa3 the cheapest. As a result of research, cheinica.1 and
otherwise, dealiirg 1argi:iy with ilie recovery of tlie acetic acid and solvents used, it is proha1)ly possilile to triaiiufactiire (lelanese brand yarii today a t a lower tot.al cost thaii any of the other synthetic fibers. Tllis statement is supported by the remut reductions in price of Celaneso bri~iidyarn. Recent Developments
Aruong other iuore or less recent developmciits (hie to rcsearch iii this field map he inentiorled the delustered and hollaw-filainent yarns of all varieties: and especially of tha
Inspection Room, Indusfrial Rayon C ~ r p ~ r a f i o n
viscose rayon t,ype. While the delustered wyou is now iii very wide use, the hollow or Celta yarn is not so well knowii in America. The extremely fiuc Beniberg yams are also new, as well as the finer denier of Celanese brand yarns and filaments. Undoubtedly the latter are produced by the stretchspinning process. These fine-filament yarns are tlie ncarcst approach to t,im silk in handling and appearance that man has ever produced, and in many eases it is difficult for even an expert to distinguish the synthetic yarn goods from true silk without special tests.
precipiVdting Ixitli is reinoved. I t i5 ais" sornetimes desirable to beat-trcat tlie spun filler a t 100-110" C. (ZlZ-23O0 F.)I or to give it a caustic-soda mercerizing treatment in order to obtain an increased tenacity. The length of the passage of the thread through the prcr:ipitatiiig hat,h, as well as ot,lier details of the process, varies sornewhat with the composition of tlie hath, its temperature. and other conditions. I n general, oii account of the stretchspinning process, spinnerets with rather large holes are used. I h t h bobbin and ceutrifogal pot spiuuiug can he used in tlie Lilienfeld pnicess. Owing to the high acidity of
strengtli of tlie acid, teinpcrature, and other conditioiis. It is used iit this way t,o produce eertaiii special finishes on cotton, in prcliinentizing paper, etc. I n fact, a precipitating hath containing 500 grams of sulfuric acid per liter was a t one time used in t.he spiuning of cupranmonium silk in order to obtain increased tenacity due to the prrchmeiitising action of the strong acid. Uudoubtedly this same parchmentizing effect is largely responsible for the increased strength of the Zilienfeld yarn. On the other hand, it has recently been shown that auy treatment which tends to assist in a niore rcpdar arriingement
Lilienfeld Viscose Yarn
The Lilienfeld niodification of tho viscose process was first wed iu 1928. The product is known as Lilienfeld yarn and is usually stronger than any other type of viscose rayoii, although i n some cases this additional streiigtli is obt.ained a t a sacrifice of other properties. There are numerous rnodifications of the Lilienfeld process which can he used with either the regular viscose spinniug solution or a special cellulose solut.ion, hut in each case tlie essential features are the use of a very strongly acid precipitating bath and a considerable stretchiiig of the filamcnt,s both between the spinneret and the thread guide and hctweeir this guide and tlie thread-collecting device. While cortain other changes in the viscose process are necessary in order t,o ohtain the best results, the above spinning conditions give a considerably st.ronger yarn with even the ordinary viscose spinning solution. It has been stated that it is possible to produce viscose yaru with a tenacity as high as 7 grums per deirier from cit.hcr sulfite pulp or linters, by the Lilieufeld process, by cooling tlie soda-cellulose well io tlie shredders, treating with aboni twice the usual yuaiitity of carbon disulfide, arid spinning the very viscous solution into the strongly acid-precipitatiiig bath a t a low temperature, with stretching, as ment.ioued above. The actual combination of conditions which give t,lie best resu1t.s varies more or less according to a nuinher uf factors, and in some eases it is desirable to permit the freshly precipitated filaments to pass some distance through the air before entering the collecting device, where the strongly acid
Acetate Silk Dry-Spinnine. Unif in Precess 01 Construction.
Kohorn Company
of the cellulose urrita iu the regemrated cellulosc yarn will
teiid i o increase its st,rength. A similar inosease iii strength is iil,t,ained by the action of dehydrating agents which aotivate certain priniary linkages between the cellulose units.
It is possible that the stretching action may assist in thismorn systematic arrangement of the cellulose units in the fi1ameiit.s. T h e gelatinous couditioii of the fiber, due to the strong stilfnric acid present, may also assist this rearrangement of the irrolccules or aggregites. At the same titiio the strong dehydrating action of tlie acid niay serve as a dehydrating agent t,o activate ccrtain primary valencies bet,weeii the cellulose iillit8. Butyrate and Ether Silks
writer had the opportunity of seeiiig considerable of the special maolrinery in the process of constroction. In tho usual process of viscose rayon manufacture the Srcshly spun and still wet viscose filaments arc collected on the bobbin or in the spinning pot while they are still wet wit.h the :icid-precil,itating solntioii, and usually the first step is the reiiioval OS this free acid by washing aiid neutralizing the yarn, either on the bolrlriiis or in the cake. In some cases tlie freshly precipitated yarn is wound into skeins tiefore attempting to remove the acid solution. .As the hohbin-spun filarnetits are not yet twisted into yarn, they are usually first wound from the spianing bobiin ont.0 special winding spools for twisting arid then twinted while rewiiidiiig onto another similar set of spools. I n some cases the gam is twisted dirr:ctly from tlie spiiiiiirig bolibiris, instead of first winding it onto the winding spools. I n any event the nest step is tu wind t.he twisted yarn froin either the spinning-pot cake or the twisting spool into skeins for washing, neutralizing, desulfurizing, bleaching, oiling, etc. If the acid is not removed from the yarn mliile on the bobbin 01' in the cake, the yarn must he kept mct chiring all of t,hese winding arid twisting iipcratioris ttrit,il all acid is rrinoved from tlie skeins; ot,her-
More than a hundred patents have heen issued witliiii recent years upon the preparation of the cellulose ethers alone; t,be principal use for which appears to be in the manufacture of spnthet.ic yarns. It has recently been announced that a plant will be built by tlie IA France-Kohorn Cninpauy to ttiatiufactitre bubyrate silk. This product wasdeveloped in tlie experimental plant. of tlie Kohorn Conipany, at Chemnitz; Germany, rvhere the vrittv recently sitw samjrlos of liotyratr, silk fabrics. These Sabrivs appear very similar to those of acetate i l k . Xnrnerous pat,eiibs hasp lmii granted recently for tla: manufacture of synthetic yarns Emm mixed csters of cellulose as m:ll as rnixtirres of t,wo iliffcrent cellulose est,era, and at least one pmdrrct of this type has been inanofactused t.o a liinit.ed extent, in Europe. ;\Iaiiy patents have also bcerr granted f o r the iriatiufacture of syntliet.ic yarns from protein materials, irmluding true silk waste; but as yet iioiie of these have appeared upon tho market aiid it, is unlikely that they will in the near future. Xevertheless KO do have severa.1 artificial wools on the nrarket, all of cellulosic origin. Another prodtict aloiig soniewhat tlic same litre is tlie pyridine viscose of Doi:tor Karrer oE Ziirich. This looks like ordinary use rayon, but on account of tlie basic pyridine group attached to Teerfilo Deparimenf Winding Section, American Bember8 Corp~rstion the cellulose molecule can be dved with acid dvestuffs. This yznl has not heenhrarketed atid ;krhaps never will tie, but., along with Professor Kamer's amino- wise the yarn will be tendered or destroyed by the concentrac,ellulose, offers some i ~ r yinteresting evidence in favor of tioo of the acid during drying. The wet yarn has lunch less the chemical theory of dyeing fibers containing acidic or resistairce to stretching and a considerably lower tensile basic groups. strength than t.he dry rayon yarn. Moreover tlie handling of the v e t yarn contairiing the highly corrosive rlilttte sulfuric American Research wid is qtiite a problem. I n tlic Ihandwuod process, the freshly spun and untwisted Khile nost of tlie research upon the synthetic fibers has viscose filaments are collected on a special, rather large, heen conducted abroad, the first cellulose acetate silkn-as pro- flanged bobbin or spool, made of aluminum or one of its alloys duced in America, new Bost.on, by a conipany later absorbed and with a perforated spindle, each carrying 6 to 8 ounces of by the Celanese Corporation of America. In many ways the yarn. lfy means of a suit,alile special mechanism resembling present product of t.liis company is in the writ.cr's opinimi mine of the package-dyeing apparatus, this yarn, while still superior to other synthetic fibers now on tho market. wounil mi the spool, is washed, desulfurized, bleached, soured, Arrother American development is the manufacture of what iieiitralized, washed, dyed and sized if desired, arid dried, is stated to be a new variety of cuprammonium yarn by tlic before rewinding and twisting. thriiess Corporatiom, a subsidiary of the Welsbacb Conipany, The Brandwood vashing machine for the spools, which at Gloucester, X. J. H, S. Miner and F. C. Nonemaker have constitotes a very important part of the apparatus, is conbeen closely associated with this work. Samples of this yarn structed in swli a manner that a convenient number of the show it t o be of high quality. spools, the shanks of which are perforated, fit over the perforated spindles or carriers of the washing inachirie and are Brandwood System secured in place by a suitable clamp on the end of each carrier. The Brandwood system of treating or finishing the spun The wash water and other solutions are supplied from tanks viscose rayon yarn \vas developed particularly for the viscose or other sources, and carried, through suitable piping, t o the process, but may also he used in certain other processes of interior of the perforated carriers. The spools, and spindles synthetic fiber inantifacture. Although the Brandwood carrying them, are rapidly rotated by nieans of a belt and system's iiew plant was riot in operation last sitmiiier, the pulley arrangemerit and the liquid is carried from t.lie inside
466
I S D U S T R I A L A S D EiVGIit-EERISG CHEMISTRY
T’ol. 22, KO.5
Plant of American Glanzstoff Corporation after Completion of First Unit on November 1, 1928 Plant of American Bemberg Corporation in background
of the spindles through the rayon by centrifugal force. Tanks or other collecting devices are provided for the recovery of the used solutions. By forcing air through the apparatus the rayon is dried. The dried yarn is twisted on the regular type of machines, with slight modifications. The twisted yarn is wound onto bobbins of the same capacity (6 to 8 ounces) as the original spool, so as to give a continuous thread, free from knots. The final winding onto cones, pirns, tubes, etc., is conducted on the usual high-speed rayon winders. It is therefore evident that only two handlings of the yarn are necessary-twisting and final winding onto the packages desired for use. It is not necessary to wind or handle the yarn in either the wet or skein form a t any time, it being wound directly onto the style of package adapted for its future use, after the completion of the wet-finishing operations. The Brandwood system is claimed to offer considerable economy of time, labor, floor space, and water used in the finishing operations of rayon manufacture. At the same time it is claimed to give a considerably increased yield of firstgrade yarn, due to avoiding injury of the yarn by handling while wet or in the form of skeins. It is also stated that this yarn dyes more evenly than that finished by other processes, and when the yarn is dyed on the spinning bobbin, there is also a considerable saving in time, labor, and other costs connected with the dyeing operations. Although similar proposals have been made in the past for treating the rayon on the spinning bobbin, Brandwood appears to be the first to carry these treatments through to the dyeing and sizing of the yarn and his plan appears to offer considerable advantage over some of the processes now in use for finishing viscose rayon. Statistics
At present there are about thirty synthetic-fiber plants in the United States, as compared with about nineteen in 1927 and fourteen in 1925. As shown in Table I, these plants manufactured 123,130,000 pounds of yarn in 1929 and it is estimated that they will produce 162,350,000 pounds, an increase of over 30 per cent, in 1930. The production in 1927 was 75,555,439 pounds, valued a t $106,468,752, while the 51,902,491 pounds produced in 1925 were valued a t $88,007,873. On this basis the 1929 production was probably worth about $150,000,000 and that for 1930 may be worth about $190,000,000, an increase of about 115 per cent over 1925. On the basis of about 20,000 employees in 1925 and 27,000
in 1927, it is estimated that with the present production there are about 43,000 employees and that this may average about 55,000 during 1930. Knowing that these workers received in wages and salaries in 1925 about S25,500,000 and in 1927 about si32,600,000, we may assume that the increased number in 1929 received about 847,300,000 and may receive about S58,300,000 in 1930, an increase of over 125 per cent in five years. All of which goes to prove that this is a live and growing industry. The Saturation Point and Research
At various times in the past there has been a feeling that the maximum consumption or saturation point for the synthetic fibers was rapidly approaching. However, it should be pointed out that even in 1929 the world’s total production of these fibers was less than 3 per cent of that of the natural fibers. Without the numerous and very remarkable improvements and developments in both the quality and cost of these manufactured fibers, in which both the chemist and chemical engineer have played such important parts, undoubtedly the saturation point would have been reached long ago. The demand today in America for the synthetic yarns is not for the cheapest products, but for the best that can be produced. This is just as it should be and every progressive manufacturer recognizes this fact. Every improvement in either quality or cost opens up many new uses and outletsfor these products. Therefore the interest in research upon all phases of syntheticyarn production is continuing. Future of the Synthetic Fibers
While the developments and improvements in the manufacture, quality, and cost of the synthetic fibers during the past forty years have been tremendous, the developments and changes taking place today are even greater than ever before in its history. Every advance in this field has been-and isfounded entirely upon research, Most of this research has been in either strictly chemical or chemical-engineering fields. As compared to the wonderful progress in chemical fibers, the textile industry, with a few notable exceptions, has been standing still, rooted in its own ignorance in the fundamentals involved in almost every step of its manufacturing processes. Undoubtedly one of the greatest changes in the immediate future will be in the position of acetate silk in the syntheticfiber field. Practically every large synthetic-fiber manufac-
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INDUSTRIAL AND ENGINEERING CHEMISTRY
turing company is either directly or indirectly interested in the manufacture of yarn by the acetate process and the Celanese companies are practically the only independent group of synthetic-fiber manufacturers in the world today. Another trend in the industry in the past has been the gradual elimination of the nitrate process in favor of cheaper methods of manufacture. While the present nitro yarn is very satisfactory, the cost of manufacture is undoubtedly higher than that of any other type. I n 1928 by far the largest part of the profits of the Fabrique de soie artificielle de Tubize of Belgium, which manufactures nitro, viscose, and acetate yarns, was derived from the acetate process, and this company has recently announced that it will discontinue the manufacture of nitro yarns. I n the cuprammonium field the tendency is towards fine and malti-filament yarns, and remarkable progress has been made along this line. Although the cost of manufacture by this process is probably higher than that of either the viscose or acetate methods, Bemberg yarn has a higher elasticity than viscose rayon and the fine-filament cupra yrirns are in big demand, especially by the knit-goods trade. I t is possible that the stretch-spinning processes now in development by the Celanese companies may rival these very fine cupra yarns in the near future. Hollow-filament acetate yarns are also a possibility of the very near future. I n the viscose field the tendencies are towards finer and more filaments, as well as stronger yarns with a greater elasticity and more even dyeing properties. The hollow-filament rayon yarns seern to be gaining ground, although they are not yet manufactured in America commercially. Of course, the matter of costs is always in the foreground in
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every process and, with the increased competition of the acetate yarns, this problem will probably become more acute in the viscose industry in the near future. At present very little effort is made to recover the chemicals or by-products of the viscose industry and developments in this field may be expected in the near future. The so-called artificial wools also come under the classification of the synthetic fibers and a number of synthetic products of this type have been on the market since shortly before or during the war. Large quantities were manufactured in Germany during the war and it has been stated that they can now be produced in England a t less than 40 cents a pound. Most of these products are of the viscose type and some develop ments in this line are possible. Novelty yarns of every type are, and will be in the future, in great demand by all branches of the textile industry. I n spite of all the enormous increases in the production of the synthetic fibers within recent years and all that we have heard regarding the “saturation point,” the real and permanent saturation point is just as far off today as it was ten years ago, if the research and developments of the past are continued a t the same rate. It is true that the sales competition will be more keen in the future and that certain unprogressive plants may pass into the discard, but this very competition will be the greatest stimulus to research and further advancements that the industry has ever experienced. Probably no other branch of the chemical industry offers any greater o p portunity to the chemist and chemical engineer today. Literature Cited (1) Woolf, Tezlile World, 77, 645 (1930).
Manufacture of Chemical Cotton’ W. Donald Munson SOCTHERN CliEMICAL COTTON CO., CHATTANOOGA, TENN.
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0 ARTICLE of commerce has contributed more t o
the industrial and economic development of the South than cotton. Investments of recent years in cotton industries have been of vast proportions and of great significance. History.of Development The use of cotton as a textile fiber is of prehistoric origin; and today, as a raw material for the textile industry, it is regarded as the universal fiber. The importance of cotton as a chemical raw material is of more recent development. For years it has been regarded a s the standard for cellulose, since from cotton is obtained the purest cellulose known in nature. With the outbreak of hostilities in 1917 and the increased demand for cellulose for the manufacture of munitions, the War Industries Board ordered the leading cotton-oil mills to install additional delinting machinery and commandeered every pound of residual fiber that could be removed from the cottonseed. While formerly the larger part of this byproduct mas used in mattresses and bedding, practically all of the increased production during the war mas con’ Received February 17, 1930. Presented a t the General Meeting under the auspices of the Division of Industrial and Engineering Chemistry, a t t h e 79th Meeting of the American Chemical Society, Atlanta, Ga
April 7 t o 11 1930
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sumed in the manufacture of guncotton and nitrocellulose powder. With the signing of the armistice a paramount problem was presented in the utilization of this now surplus war material. Several of the large producing interests undertook the development of a cotton-pulp for paper manufacture, the paper industry being the largest potential consumer of cellulose. With the consumption of the surplus mar material and the increase in cost of the cotton fiber other cheaper competitive pulps largely displaced cotton in the paper mills. Cotton, of the long staple variety, on account of its higher cost than wood pulp and other cellulose, could not be considered as a raw material for the various cellulose-base chemical products. It has been through the utilization of a by-product from the cottonseed, known as cotton linters, that this economic problem has been solved. Cotton linters, although a by-product of the oil mill in the process of crushing and extracting the oil from the cottonseed, have now become a very important source of cellulose. Since the war those industries employing cotton cellulose as a base have experienced phenomenal growth. The estimate of linters purified in the United States in 1929 for chemical purposes is 300,000 bales, 35 per cent of the total linter consumption. With the increased demand it is expected that within a few years cheaper methods of production will
