US2840446A - Process of cyanoethylating native cotton fibers with an aqueous emulsion of sodium hydroxide and acrylonitrile - Google Patents

Description

June 24, 1958 Filed Oct. 10, 1955 FIG. I

J. COMPTON ETAL 2,840,446 PROCESS OF CYANOETHYLATING NATIVE COTTON FIBERS WITH AN AQUEOUS EMULSION OF SODIUM HYDROXIDE AND ACRYLONITRILE 6 Sheets-Sheet 1 l l I S '2 I If "'5 .5

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ATTORNEYS June 24, 19548 J. COMPTON ETAL PROCESS OF CYANOETHYLATING NATIVE COTTON FIBERS WITH AN AQUEOUS EMULSION OF SODIUM HYDROXIDE AND ACRYLONITRILE 6 Sheets-Sheet I 2 Filed Oct. 10. 1955 T cozuuzu aoz vT co ouom vT :o o ut 200 V O 7 On ON 0 own ud mm m 03H INVENTORS.

5 7 MW 5 mm P E M MW o CM ,0 s w K MA CM M June 24, 1958 Filed Oct. 10, 1955 FIG. 3

69 6. .Ol4lb. N0 OH/lb. Cotton 63 0. O O 69C. .O2llb. No OH/lb. Cotton 63" c 0 IO 9* Solubihty Llmlf H O In J. COMPTON EI'AL 2,840,446 PROCESSOF-CYANOETHYLATING NATIVE COTTON FIBERS WITH AN AQUEOUS EMULSION 0F SODIUM HYDROXIDE AND ACRYLONITRILE 6 Sheets-Sheet 3 Acrylonlfrilo 69 C. o 63 C.

25 0. --Cold Circulation -Reoction +Neutrulizotion i Time " id m n 03H INVENTORS. JACK COMPTON BY OATESBY P. JONES ATTORNEYS June 24, 1958 J. COMPTON ETAL 2,840,446

PROCESS OF CYANOETHYLATING NATIVE COTTON FIBERS WITH AN AQUEOUS EMULSION OF SODIUM HYDROXIDE AND ACRYLONITRILE Filed Oct. 10, 1955 6 Sheets-Sheet 4 l I I l I l I I do Lo 0 N [0'0 cow 2: 60 0-0-- as 1 E 1 5 0' II oo 5 I I I I l I I I SE *N 0' 0 mm (DID I l l I I F 1D In Q IO N C 21-00% INVENTORS.

JACK COMPTON BYOATESBY P. JONES ATTORNEYS /o 0.0. P. /o N.

n 5 J. COMPTON ETAL 2,840, 46

PROCESS OF CYANOETHYLATING NATIVE COTTON FIBERS WITH AN AQUEOUS EMULSION OF SODIUM HYDROXIDE AND ACRYLONITRILE Filed Oct. 10, 1955 6 Sheets-Sheet 5 FIG. 5

0 N. .OI4Ib. No HO O.D .P. 9 O N. .021 lb. Nu HO O I I I l l x s 8 l0 s a IO H2O H2O INVENTORS.

JACK COMPTON OATESBY P. JONES fimwmfimmfi a ATTORNEYS Patented PROCESS OF CYANOETHYLATING NATIVE COT- TON FIBERS WITH AN AQUEOUS EMULSION OF SODIUM HYDROXIDE AND ACRYLONI- TRILE Jack Compton, Charlottesville, Va., and Catesby Perriman Jones, Bethesda, Md., assignors to Institute of Textile Technology, Charlottesville, Va., a corporation of Virginia Application October 10, 1955, Serial No. 539,486 6 Claims. (Cl. 8-120) This invention relates to the reaction of acrylonitrile with cotton and has for'its object the provision of improved cotton products and a process of reacting acrylonitrile with cotton fibers in the form of bulk fibers, yarns, or fabrics to improve the properties of the cotton while maintaining the natural structure of the fiber and most of the properties of ordinary cotton. Our invention pro vides an economical and practical process of producing our improved cotton products with a minimum loss of chemicals through washing, neutralizing and undesirable by prod-uct formation. The improved cotton products of our invention are a partially cyanoethylated cotton, but

they have the-important distinction of retaining the natu ral fibrous form of native cotton fibers, and their crystallinity in'a substantially unaltered state.

Several processes'have been proposed heretofore for treating cellulose with aqueous solutions of sodium hydroxide and ac'rylonitrile-to effect from a partial to a complete cyanoethylation, usually resulting in a soluble with but a relatively small proportion of the cellulose giving:cyanoethylcellulose which; may 'be represented as Cell -OCI- I' CH CNQ We have found that very desirable cotton products can be formed by effecting but,

apartial etheritication of the celluloselmolecule, resulting in butfrom 0.006 to 1.0 cyanoethyl group per anhydroglucose unit (equivalent to from 0.50 to 6.50% nitrogenbased onQthe: weight ofwcyanoethylated cotton). In the preferredandmost advantageous embodiment'of our invention, we control the conditions to'combine but'from 0.1wto 0.6 cyanoethyl group per :anhydroglucose unit.

The following table shows the relationshipbetween the cyanoethyl groups'per anhydro-glucos'e unit nitrogen? content of the cyanoethylated cotton:

amine Table A Cyanoethyl Percent N Groups per Anhydro- Glucose Unit Our invention is specifically directed to the treatment of native cotton .because we aim to produce an im-' proved cotton fiber and cotton is peculiarly suited to our process. By native cotton we mean natural cotton Which has neither been changed chemically nor its molecular arrangement altered, although it may have been treated to remove gums, waxes and foreign matter. While cotton is a relatively pure form of cellulose, the fibers are considered to be formed of three distinct-types of layers, each having a different physical structure, consisting of amorphous and crystalline components. Mild reaction conditions, such as the preferred cyanoethylation procedure herein described, are required to maintain this, desirable fi'ber structure. In particular the relationship between the amorphous and crystalline components. should be maintained. One further characteristic of useful native cotton fibers is that the degree of polymerization of the cellulose varies from about 1500 to 4500 and in this respect it. differs .from viscose rayon which a has a degree of polymerization of from about 150 to 450. In general, all regenerated cellulosic fi'ber materials have I a greater proportion of the amorphous component than native cotton and the crystalline component is characterized by having the mercerized cellulose molecular ar-v rangement. Cotton thus has a different structural arrangement and responds differently than regenerated eellulose when treated with such chemicals as sodium hydroxide and acrylonitrile. Because of its structure, cotton is a very important textile material and our process maintains its structural identity. I

For the cyanoethylation of cotton, we have discovered a very important relationship involving the concentration of sodium hydroxide in solution, the amount of sodium hydroxide solution applied to the cotton with the acrylo nitrile, and the time andtemperature of the reaction of acrylonitrile with the cotton while in thepresence of a solution of sodium hydroxide to effect the amount of cyanoethylation necessary to produce the improved cot-' ton products. We can carry out our process in produc- 1 ing our. improved cotton products without excessive loss in sodium hydroxide. and in lay-product formation which results in a loss of acrylonitrile. I

In accordance with the process of our invention, We apply to thecotton a mixture of an aqueous solution of sodium hydroxide and acrylonitrile, which mixture du,r-

ing treatment is in a state of emulsion, and preferably by circulation of the emulsion over'and through the cotton fibers. We may form the emulsion in any suitable way as by mechanically mixing the sodium hydroxide solution, a surface active agent such as Aerosol-OS (isopropyl napthalene sodium sulfonate), and the acrylonitrile, and apply this emulsion to the cotton. An emulsion formed by mechanical agitation of an aqueous solution of sodium hydroxide and acrylonitrile may also be usedas is described in our prior application, Serial No. 435,904, filed June 10, 19 54, now abandoned. The emulsion may be formed, as thereindescribed, by adding the sodium hydroxide solution to the acrylonitrile as it enters a circulating pump which in turn circulates the emulsion over the cotton very shortly after the emulsion is formed. 1 :Such a mechanically formed emulsion is not stable and separates quickly. By the use of a surfaceactive agent, such as Aerosol-OS, the emulsion may be Sta" bilized. 2 a

In carrying outour invention, precautions mustbe taken to direct the addition of the cyanoethyl groups .-CH -CH -.CN without -or with-no appreciable hydrolysis to form carboxyethyl groups In using the lowsodiumhydroxide concentrations in our process we avoid hydrolyzing the nitrile CN to carboxyl COOI-I andalso neither depolymerizethe crystalline cellulose nor increase the proportiono'fthe amorn vention are similar in appearance, hand, :and processing 7 characteristics to cotton, but differ prirnarily and significantlyin that they are permanently resistant to micro organism attack, suchasfcausemildew; more resistant to wet. an dry h at degradation; more r c p e to m ny dyes of all classes, including acid dyes; and more resiste ant to abrasion.

In our copendjng appl cation, ,Serial No. 442,762 fi led July 12, 1954, now Patent ,No. 2,786,258, We describe and claimour imwoved fibrous ,cottonproduct, and a process for treating cotton Ifibers with aqueous solutions of sodium hydroxide, preferably in a steeping process, and under the conditions described herein, but in the process ofithat application the presteepedcotton fibers are treated with liquid acrylonitrile containing some water. In the process of our, copending application, Serial No. 435,903, filed June .10, 1954, now Patent No.

2,786,735, the'presteeped cotton fibers arei tr'eated with.

acrylonitrile in the vaporphase.

We have discovered asignificantrelationship between the concentration of sodiumfhydroxide, the amountof water with respect to the cotton andflthe, acrylonitrile, and the temperature and time of treatment, of the cotton to form our improved ,cotton projduct efficiently, with a minimized lossof acrylonitrile through by-product formation. Our invention is based upon a control of the quantities of reactants and the conditions of treatment to form .cyanoethylated cotton having the {required nitrogen content and characteristic fibrous character of native cotton efficiently. The process of the invention'comprises, (1 the 7 use of aerelatively low concentration,of sodiuni hydroxide inthe aqueous solution'whichj results 'inlincreased reaction efiiciency, (2 the use ot'ian .acc-uratelygcontrolled quantity of water in the emulsion with "acrylonitrile to achieve uniform reaction with the cotton and minimize by-product formation; (3) the control of temperature and (4) a control of time in relation to the nitrogen content of the cotton.

One of the primary reaction variables is the sodium hydroxide concentration. This should be kept as low as practicable, preferably in the weight ratio of sodium hydroxide to cotton of from 0.005 to 0.10. The reaction efficiency, as used herein, is defined as the ratio of the theoretical amount of acrylonitrile required to give the found nitrogen content of the cyanoethylated cotton to the total amount non-recoverable, expressed as a percentage. The non-recoverable acrylonitrile includes the acrylonitrile fixed by reaction with the cellulose, that reacting with the water to form beta-beta-oxydipropionitrile (ODP) and other by-products. There is also a significant relation between the water concentrationin.the'emulsion and the temperature, the reaction efficiency increasing with a reduction in the water content, especially when this is accompanied by increasing temperatures.

Several variables atfecting the nitrogen content of the cyanoethylated cotton include variations in the temperature and in the amount of. sodium hydroxide based on the weight of the cotton. For example, withrespect to the sodium hydroxide efiect, the nitrogen contentof the cotton can be increased from "a mean of 2.48% to a mean of 3.02% when the weight ratio of sodium hydroxide to cotton is increased from 0.014 to 0.021. With respect to the temperature effect, the-nitrogen content of the cotton can be increased from a mean of'2.52% to atmean of 2.98% by increasing the reaction-temperature from 63 C. to.68 C. 'Ifthe reaction time is constant, the two variables, sodium hydroxide content and reaction temperature can'bechanged individually or togetherto control. the extent of cyanoethylation as indicated by the nitrogen content; Advantageously, the reaction temperature should be :as high as possible and reaction time as short as-.possible.

In its complete aspectsour invention comprises the circulation of an aqueous emulsion of sodium hydroxide solution in acrylonitrile while-in contact withsthe fibers of native cotton. in whichthetotal'water-phase, representing from 50% to 150% of the .weightofithe cotton, contains from 0.50 to 10 percent .of sodium hydroxide at a temperature of from 24 C..to 93? C. and .for from 1 to 360 minutes to cyanoethylate .preferentiallythe amor phous portion of the cellulose :to'such anextent that the cotton contains from 0.5 to 6.5% .of nitrogen, the ratio of the weight of sodium hydroxide toathe..weight.of the cotton being from 0.005 to 0.10. H v

In the accompanying drawings:

Figs. 1, 2 and 3 are curves showing the effects ofiyariations in the water in the liquid phase .at different temperatures and sodium hydroxide concentrations;

Figs. 4 and 5 are a series of curves showing the percentages of ODP with variations in the sodium hydroxide,

temperature, time and Water in the liquid phase;

Figs. 6 and 7 are a series of cu'rvesshowing the effects of variations in the sodium hydroxide in the liquid phase, with variations in the sodium hydroxide based on the cotton, water in the liquid phase, and time.

The process of the invention may be carried out in any suitable kind of equipment in which the emulsion of the aqueous sodium hydroxide solution in acrylonitrile, at the proper temperature, is circulated in contact with the cotton for a sufficient time to effect the reaction resulting in cyanoethylation of the cotton. The Gaston County package dyeing machine which treats packages .of yarn in kiers is one suitable kind of machine for practicing the invention. a'Gaston County packaging machine containing 70packages of cotton yarn in the two kiers were treated in each operation. The package'weights were usually one-pound, butthis varied slightly from run to run. By winding the cotton yarn on'Davidson springs and compressing them to the maximum extent, it was: possible to-putas much 98 pounds on the 70 packages. The ratio of the treating In the particular operations herein described,

components of the emulsion" tocotton c ould thusbe; varied over a wide range. Thefollowing representative operation was carried outwith 70 packages of cottonyarn and is typical of the other operations whichwere carried out under the variable conditions reported in the accompanying drawings. d I

I To 530 pounds of acrylonitrile contained in a circulating tank connected to'the two kiers, a mixture of 1 pound of sodium hydroxide and 0.5 pound of Aerosol-OS dissolved in 42pounds of water was added. The mixture was then circulated through a centrifugal pump, while agitation was supplemented by the use of a Lightning mixer placed in the top of the circulating tank. After circulating for 30 minutes in this way at room temperatu-re, an emulsion of the sodium hydroxide solution in the acrylonitrile was obtained. The two kiers of the package treating machine were then loaded with 67 pounds of cotton yarn containing 6 percent moisture in the usual manner and after closing the kiers the emulsion of sodium hydroxide solution in acrylo'nit'rilef was pumped through the packages at room temperature, 24 C., for 30 minutes. This resulted in a liquor to cotton ratio of 10.7 to 1. At the end of this time the temperature of the liquor, while being continuously circulated through the packages, was raised over a period of 5 minutes from 24 C. to 68 C. The rate of flow of the liquor through the packages was approximately 250 gallons per minute. 30 minutes, at 68 C., after which the liquor was cooled to room temperature and the sodium hydroxide neutralized with an aqueous phosphoric acid solution. The acrylonitrile remaining in the yarn in the kiers, of the package machine was then removed by washingwith water. It was found that about 90% of the acrylonitrile retained by the packages was removed by three charges of water weighing roughly 700 pounds each. These wash waters were collected and, with thespent acrylonitrile liquors from the reaction, subjected to flash distillation for recovery of the unreacted acrylonitrile. The yarn packages, after thorough washing in the package machine with water to remove all traces of acid and salts, were removed, centrifuged, and carried to a package dry: ing unit, where warm air was blown through them until they were substantially dry. From the 7/1 cotton yarn treated in this instance, 81 pounds of cyanoethylated cotton yarn, containing 4.5% nitrogen, were obtained. Simultaneously, with the reaction of acrylonitrile with cotton, the acrylonitrile also reacted with par-t of .the water present, so that 30 pounds of. acrylonitrile went into lay-product formation while 14 pounds of acrylonitrile were fixed on the yarn. This gave a ratio of acry lonitrile going into by-product formation to acrylonitrile fixed on the yarn of 2.1 to 1, or a reaction efiiciency of 32%. The effective initial caustic concentration was calculated to be 2.1 percent and the ratio of caustic to cotton was 0.016. d

In another example, 400 pounds of acrylonitrile containing 5.1 percent ODP were placed in a circulating The circulation was continued for tank connected to the kiers and a mixture of 3.65 pounds of sodium hydroxide and 0.5 pound of Aerosol-OS dissolved in 49 pounds of water added. The mixture was then circulated through a centrifugal pump while agitation was supplemented by use of a Lightning mixer placed in the top of the circulating tank. 7 After agitating for 30 minutes in this way at room temperature, an emulsion of the sodium hydroxide solution was obtained. One of the two kiers of the package treating machine was then loaded with 38 pounds of yarn containing a 6' percent moisture in the usual manner, whereas the other kier was cut out of the system. This resulted in a liquor to cotton ratio of 10.1 to 1. After closing the charged kier, the emulsion of sodium hydroxide solution in acrylonitrile was pumped through the packages at room temperature, 24 C., for 30 minutes, reversing the direction of flow at 4-minute intervals.

At the end of this time the temperature of the liquor while being continuously cir culated uthroughthe packages was raised over a period of.

minutes at 38 C., after which the liquor was cooled to roomtemperature and thesodium hydroxide neutralized with an aqueous phosphoric acid solution. The packages of 7/1 yarn after thorough washing and drying, as described above, weighed 45.4 pounds and upon analyzing were found to contain 4.3 percent nitrogen. The spent liquor from the reaction sampled at the completion of the reaction contained 10.9 percent ODP. Thus 16 pounds of 'acrylonit-rile went into by-product formation, while 7.4 pounds were fixed to the yarn. This gave a ratio of acrylonitrile going into by-product formation to acrylonitrile fixed on the yarn of 2.2 to 1, or a reaction efficiency of 31 percent. It will be noted that the effective caustic concentration in this run was 7.1 percent in the water phase of the emulsion initially, and the ratio of caustic to cotton was 0.10.

A sample of yarn taken from the above run after the 30-minute circulation of the treating liquor at 24 C. was freed of caustic and acrylonitrile by acid neutralization and water washing. After drying the cyanoethylated yarn had a nitrogen content of 2.2 percent, indicating that the reaction proceeds fairly rapidly during the circulation period prior to raising the temperature to38 C.

The foregoing typical operations were carried out many peratures and varying periods of treatment.

The curves of Figs. '1, 2 and 3 indicate'that the water and sodium hydroxide approach and equilibrium between the liquid phase and the cotton during the first ten minutes of circulation. The water concentration of the liquid phase is reduced to about one-half its original amount while the sodium hydroxide concentration is reduced ten-fold during the first ten minutes of circulation. When the mixture contained 6 percent water at the beginning, the water content of the liquid phase approached the solubility limit of waterin acrylonitrile at 24 C. (which was the approximate temperature maintained during cold circulation).

As the reaction temperature was increased, the water" was dissolved in the liquid phase. In the series of experiments performed with 6 percent water in the liquid phase I at the'beginning, slightly more than 6 percent appeared after the reaction mixture was heated. This is probably caused either by water retained in the system or regain moisture in the yarn. With 8 percent water at the start, the liquid phase approached 8 percent water content as a limit during reaction. At 10 percent, the limiting factor for the water content during the reaction period was the solubility of water in acrylonitrile, so the water content of the liquid phase did not approach 10 percentin this series. Increasing the sodium hydroxide concentration from 0.014 lb. to 0.021 lb. per pound of cotton had no apparent effect upon the distribution of water between the yarn and liquor phases.

The operations show that the variable that has the most effect upon reaction efficiency appears to be the sodium hydroxide concentration and that it should be kept as low as possible for the desired nitrogen content of the yarn. v

The data in Fig. 4 compare the rate of ODP formation for each operation. These data indicate that ODP formation is approximately linear with time. At 6 percent water in the liquid phase there is little difference in GDP formation when other reaction variables are changed, although the higher sodium hydroxide concentration is associated with the greatest ODP formation.

At 8 percent water, the effects of both temperature and sodium hydroxide upon ODP formation are shown,

If either-reaction temperature or sodium hydroxideconacentration is increased, the ODP formation isjalsoyincreasedfi i q At 10'percent water, it is apparentthat the sodium hydroxide concentration has a greater effect upon ODP formation than reaction-temperature; since the slopes of the lines comparing ODP formation-at different sodium paring different reaction itemperaturesfl j-InFig; 5 the percentage nltrogen" hydroxide concentrations arehigherithan thosecome esting to note that the nitrogen content ofthe yarn is decreased in most instances as'thelwater inthe reaction was absorbed most rapidly from the highest sodium hydroxide concentration.

It may be concluded that the rate'and extent of cyano- I ethylation of cotton may be realized alongwith a mini- 3 mum of ODPfby-product formation by'the proper control of the reaction variables of'time, temperature, initial caustic concentration in the. water phase of the caustic solution-acrylonitrile dispersion, and the related final ratio of caustic to cellulose as well as the concentration of the water phasein the acrylonitrile. p

The one-step cyanoethylation process of the invention results in (1) less handling costs in the. case of yarn treatment, (2) decreasedaby-productformation, (3) the use of .-water saturated acrylonitrile .in the reaction, and (4) decreased the overall time. for treatment. Each of these factors tends togimprove the economics of the cyanoethylation process,

This application is a continuation in-part of our patent application Serial No. 435,904, filed June 10,.1954, now abandoned.

We claim: p p

1. The process of treating native cottonfibers to effect but a partial. cyanoethylation of the cellulose and retain thenatural physical ,structureof the cellulose which comprises circulatingin, contact .with said,fibers an emulsion of an aqueous solution of sodium hydroxide in acrylonitrile at a.temperaturelofffromabout24 C. to 93 C. and in whichtthe ratio. of sodium: hydroxide to cotton by weight varies from 0.005 to 0.100; and continuing the circulation until the cotton.isbcombined with such an amount of acrylonitrile that the nitrogen content thereof varies for different reaction. conditions from 0.5% to 6.5% based on the weight of.the .cyanoeth'ylated cotton.

2. The process of claim:.1, wherein thecmulsion is circulated over the cotton :at .normal .room rtemperature fixed 'to the. yarn" and the'amounty ofODP" in the spent'reaction. liquor formed in each reactionis comparedwith the amount.

of water in the original reaction mixture." It ;is 'inter= foratime upito about minutes'and then the; emulsion isfcrrculate overfthepotton at an elevated temperature P Y fl e'"pro'ce'ss"of treatingnativecottonfibers to effect 'artial 3 cyanoethylation of the cellulose and retain the natural physicalstructure of the cellulose which com= prises circulating "ini'contact with saidfibers an emulsion of aniaqueous solution" of sodium hydroxide in acrylo nitrile," saictr' emulsion containing up tog12% of water withrespcctto'the'acrylonitrile and such an amount of sodium hydroxide thatthe ratio. of sodium hydroxide to cotton variesfrom" 0.005 'to0.l0, the circulation being continuedfora"suflicient time to combine withthe cotton such an amountof acrylonitrile that the nitrogen contentjthcreoffvaries-fordifferent reaction conditions from 0.5% to 6."5%'ba"sed"on the weight of the cyanoethylated cotton withjout producingmore than 10% oxydipropionitrile'as'a'by-product in the spent liquor.

4. Thepro'cess'oflclaim 3, wherein the circulation is continued up to 20' minutes.

5. Thepro'cessof treating native cotton fibers to effect but a partial cyanoethylationof the cellulose and retain the natural physical structure of the cellulose which comprises circulating in contact with said fibers an emulsion of"an.aqueoussolution of sodium hydroxide in acrylonitrile'at a'temperature of from about 63 C. to 79f C.,

the ratio of the weight of sodium hydroxide to the weight sodium hydroxide solution and acrylonitrile in which the water phase contains from 0.5 to 10.0% of sodium hydroxide, the ratio of the weight of sodium hydroxide to the weight of the cotton being from 0.005 to 0.10, continuing the'reaction at a temperature of frorns62.8 C(to 79.4 C. until the amorphous portion of said fibers are cyanoethylated to such an extent that the cotton contains from 0.50 to 4.5% of nitrogen based on the dry weight of the cyanoethylated cotton and in which substantially all of the original crystalline structure of the native cotton is retained, said cyanoethylated cotton having the appearance, hand and processing characteristics of the native cotton, increased abrasion resistance, in

creased tensile strength, decreased moisture absorptivity, and increased alfinity for acetate, vat, and sulfur dyes.

References Cited in the file of this patent UNITED STATES PATENTS Hanford June 2, 1942 MacGregor Sept. 13, 1949 Downey Feb. 3, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,840,446 June 24, 1958 Jack Compton et a1.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 55, for "0.006" read -=0.06=-; column 8, line 59, list of references cited, under the heading "UNITED S'IATES PATENTS", for the patent number "2,482,001" read 2,482,0ll=v-=.

Signed and sealed this 7th day of October 1958.

WIFE. AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner of Patents

Claims (1)

1. THE PROCESS OF TREATING NATIVE COTTON FIBERS TO EFFECT BUT A PARTIAL CYANOETHYLATION OF THE CELLULOSE AND RETAIN THE NATURAL PHYSICAL STRUCTURE OF THE CELLULOSE WHICH COMPRISES CIRCULATING IN CONTACT WITH SAID FIBERS AN EMULSION OF AN AQUEOUS SOLUTION OF SODIUM HYDROXIDE IN ACRYLONITRILE AT A TEMPERATURE OF FROM ABOUT 24*C. TO 93*C. AND IN WHICH THE RATIO OF SODIUM HYDROXIDE TO COTTON BY WEIGHT VARIES FCROM 0.005 TO 0.100, AND CONTINUING THE CIRCULATION UNTIL THE COTTON IS COMBINED WITH SUCH AN AMOUNT OF ACRYLONITRILE THAT THE NITROGEN CONTENT THEREOF VARIES FOR DIFFERENT REACTION CONDITIONS FROM 0.5% TO 6.5% BASED ON THE WEIGHT OF THE CYANOETHYLATED COTTON.

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