Patented Sept. 24, 1946 2,408,027 UNITED STATES PATENT ’ OFFICE 2,408,027 METHOD or 'rnm'rmo srn'rnarro mornmecaocs mans Francis Clarke Atwood, Newton, Mass” assignor ‘ to National Dairy Products Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application December 11, 1943, Serial No. 513,952 > 2 (Cl. 8-127-6) This invention relates to the treatment of syn , thetically shaped protein-containing. materials. resistant to hot water or dilute acids or alkalies. Particularly is this so if the water solution ,con tains an alkaline material such as would be pres ent in' a hot solution of an ordinarysoap. Upon the heating or boiling of such ?ber in such a solu tion it becomes soft and spongy and takes on a In particular vthe invention includes the treat ment of ?ber synthetically made from protein aceous material, such as casein, to impart thereto properties simulating those of natural protein ?bers. “slimy feel”. .The tensile strength of the ?ber Many naturally occurring materials are com and its elasticity in such a state is also greatly prised of proteins, for example, silk, wool, hair reduced so that the ?ber is readily deformed or and skins. “Arti?cial materials also may be 10 broken. Upon drying such ?ber after it has been manufactured from protein-containing material, subjected to such treatment, it becomes brittle so such as casein and other proteins and formed that further handling results in excessive “drop into various shapes, such as ?brous ?laments. pings,” if in fact the ?ber is su?iciently'?exible But such arti?cial protein materials differ in to be subjected to any further processing. Ordi many respects from natura1 protein materials. Protein-containing materials have many 'de~ 15 nary casein ?ber, in addition, does not have dye ing properties enabling itto be dyed in a manner similar to naturally occurring proteinaceous ?ber. ‘ sirable properties that render them valuable for use in fabrics of all kinds, such as covering ma terials and upholstery, and for use in articles of The ordinary casein ?ber also is subject to a change in properties due to contact with moisture clothing including clothes, shoes and gloves. 20 in the air. In humid air it is relatively plastic, These properties include the warmth, softness, ?exibility, tensile strength, elasticity and other similar properties of protein-containing mate but in dry air it is quite brittle. . From the above it wil1 be seen that the syn thetic protein ?ber as known heretofore in’ the ' rials, and are hereinafter referred to as physical properties. All proteins contain carbon, hydrogen, oxygen, 25 and nitrogen and many proteins also contain sul fur and phosphorus. The proteins are thought to art, such as that shaped from casein and hard ened with formaldehyde, is entirely different from natural proteinaceous ?ber such as wool, ' silk or fur, and is not suited for the uses to which ' such natural ?bers may be put. This difference is . so marked as.not to be simply a matter of degree. boxyl groups, and ‘are more or less chemically v30 Apparently the casein inherently is of such a na reactive depending upon their individual consti ture as not to possess satisfactory properties for contain amino and probably hydroxy and car- » ’ tution. For example, di?erent proteins are af fected di?erently by hot'water, alkaline or soap ?ber purposes. Attempts at modi?cations of the casein have not produced a ?ber which has satis solutions. Over long periods of time some pro _ ?ed the textile industries. ' In copending application, Serial Number teins also oxidize or otherwise deteriorate more 35 rapidly than others so as to become somewhat 427,940, ?led January 23, 1942, of which this ap brittle and lose their strength‘ and softness. Dif plication is a continuation-in-part, a process is ferent proteins also react di?erently with var described in which the chemical properties of ious other compounds, particularly dyes. In re synthetic protein materials may be changed by Ierring to the chemical properties of protein con 40 reaction with certain chemical compounds to im taining materials, reference is made to their abil part more desirable chemical properties without ity to combine physically or react chemically with detracting from their Physical properties. They may be made more resistant to chemical activity any other compound such as oxygen, water, acids, alkalies, and dyes. but at the same time remain soft and pliable and While the physical properties of ?ber prepared 45 retain or even improve their tensile strength and other physicaliproperties. from the proteins such as casein, including the ‘common method of soaking the shaped casein _In accordance with the Process-described in ?ber in formaldehyde solutions are satisfactory the aforesaid cog-pending application, the syn for some purposes, they are far from satisfactory thetic proteinaceous ?ber is treated in a liquid for most uses to which ?bers are to be put. With 50 containing an acylating anhydride, more particu respect to their chemical properties particularly larly, acetic anhydride in an inert solvent. .The they leave much to be desired. For example, a treating liquid comprises an inert organic solvent, ?ber prepared from a casein dispersion and such as a hydrocarbon or a chlorinated hydro ‘ coagulated, in which process it is hardened by . carbon, in which acetic anhydride and a small 7 the usual treatment with formaldehyde, is not 55 amount of acetic acid is included. The proteina 8,408,027 - 3 4 ceous ?ber to be treated is made by dispersing. . accepted by natural protein ?ber. Since one of the more important-uses of the synthetic protein casein or other proteinaceous material in an al ?ber is in admixture with natural protein ?ber kaline solvent and spinning it into an acidic and other ?bers natural or synthetic, "it is desir coagulating bath, following which it is treated able that the two should have similar dyeing prop- . with formaldehyde, washed and dried. The dried errties. It is: possible to dye the new ?ber with ?ber so prepared is immersed in the treating appropriate dyes and in baths of/the‘proper pH liquid at an elevated temperature of about 150° so that it accepts the dye at substantially the same rate, so that at the end of the dyeing opera 10 tion, a mixture of synthetic protein /?ber and, the liquid. ' ‘ other ?ber will be of substantially the same shade. q The 'proteinaceous ?ber to be treated normally In accordance with the invention, the treating contains a small amount of water which is the liquid comprises any organic ‘solvent inert with normal moisture content of the ?ber when'it is respect to the ?ber and the ingredients in the in equilibrium with an atmosphere of ordinary A hydrocarbon solvent, such as that temperatures and humidities. This is reduced as 15 liquid.‘ known in the trade as “Solvasol," is inexpensive . much as possible, in accordance with the proc and for that reason is preferred. To this is added ess in said co-pending application, since the mois acetic anhydride in an amount of 7 to 8%, and ture in the ?ber reacted with .the acetic anhy acetic acid in an amount of 5 to 7%, preferably dride in the treating liquid to form acetic acid. 51/2 to 6% by weight of the total treating liquid. This used up aceticanhydride for no good pur 20 The amount of the acetic anhydride in the above pose, and was thought to increase the acetic acid formula may vary from 5% to 15%. Amounts content to a point where it must be eliminated. less than 5% will result in some acetylation but In fact, in accordance with the process of said generally it is not sufficient to Justify the treat application, a portion of the treating liquid is ing of the ?ber by the process; an amount above withdrawn and neutralized with soda ash-to con 25 10% (unless lower temperatures are used) does ,vert the acetic acid to sodium acetate ‘which is not result in a su?lcient improvement to war to 225° F. for a period of a few minutes to an hour, following which the ?ber is removed from separated from the treating liquid. _ _ rant using a larger amount, but no harm is done It has been discovered, in accordance with the by its presence. The temperature may vary from invention described in this application, that if about 150° F. to 225° F. At lower temperatures ‘ the amount of acetic acid in the treating liquid 30 the reaction is slower, and therefore, on a com is increased, a vastly superior ?ber is obtained, nrercial scale there is no advantage in using the and furthermore, that by treating the ?ber in lower temperatures. The temperature should not the liquid containing the increased amount of be so high as to cause yellowing or softening of acetic acid, it isv unnecessary to neutralize the ?ber during treating. The maximum tem acid in the treating liquid, since the ?ber as‘it is 35 the perature will depend somewhat on the protein removed from the treating liquid will carry with from which the ?ber is made and the presence it an amount of acetic acid absorbed therein in the ?ber of ingredients which tend to yellow which is equivalent to that formed by the reac or char at lower temperatures. It is possible in tion of the water in the ?ber to be treated with all instances to operate at atemperature below ‘ acetic anhydride. In‘other words, it has‘ been 40 the harmful temperature and at which the re discovered that the moisture content of the ?ber ‘ I can be adjusted as to produce an amount of action rate permits the treatment to be concluded ' in.,a reasonable time. The temperature and acetic acid during the treating process which will treating time are also related somewhat to the be absorbed in the ?ber during the treatment if of anhydride. When ‘the temperature is the amount of acid carried in the treating liquid 45 amount lower the reaction can be speeded by larger is at a su?lciently high level. Not only’ is the amounts of the anhydride. There is no advan neutralizing eliminated in this way, but a, superior tage commercially in using the larger amount acetylation of the ?ber results, apparently due when the same result can be obtained by a. higher .to the larger‘ amount of acid in association with 50 temperature. The selection of these variables‘ the acetic, anhydride in the treating solution. will be made dependent on economic and other In accordance with the invention a ?ber may operating factors as will be apparent to one skilled , be "produced that, has a superior resistance to in the art, in view of the disclosure herein. chemical activity of the undesired type, such as The amount of acetic acid within the above breakdown by bleaching agents and deterioration ' percentage is critical if the ?ber is to have the‘ by hot water, acids, or alkalides, while at the same 55 desired dyeing properties. While the acetic acid, time it has superior chemical properties imparted as such, apparentlyv is not an acetylating agent, to it with respect to its reaction to dyestu?’s and and the acetylating reaction is apparently attrib chemicals ordinarily used in the process of nat uted to the acetic anhydride, nevertheless the urally occurring proteinaceous ?bers. The ?ber presence of. a critical amount of acetic acid has also remains unusually soft and pliable and re 60 ‘a great effect on the nature and extent of the tains or even has its physical properties im acetylatlon and the properties of the ?ber. If proved. It acquires to a greater extent those too little is present, the resulting ?lber has unde properties desired by textile operators. 'sirable ‘dyeing properties and absorbs dyestu?s' I The ?ber produced can better withstand boil which ordinarily do not dye wool. On the other ing for long periods of time in water, as well as 05 hand, id the acid concentration is too great, the in hot dilute acid solutions such as‘ are used in ?ber‘ becomes too soft and is poorly acetylated. dyeing. It is also enabled better to withstand By controlling the amountgof acetic acid between vigorous mechanical treatment combined with the above critical limits it is possible to produce ' alkaline material, such as “fulling" and “scour- I i'ng” operations, even after preparing it for dyeing 70 a ?ber which has dyeing properties closely simu-' lating that of natural wool and which resists operations. . dyes which do ‘not dye wool and is dyed'by dyes .The ?ber also is not ’only not harmed by dyeing operations, but has desirable properties in that ,it accepts dyes ordinarily accepted by natural proteinaceous ?ber and rejects dyes which are not which ordinarily dye wool and at about the same rate. In carrying out the process, a treating liquid . 2,405,027 \ i », is prepared in accordance with the above for- . mula, and about‘ 300 gallons is used for each 275 pounds of the ?ber to be treated. The'?ber is placed in the liquid and agitated therein while 6 matured as Patent No. 2,342,994 on February 29, 1945) but other processes may be employed in making the fiber, and the process is not critical. The ?ber should be treated with formaldehyde after thespinning and before the treatment in accordance with theinvention. Preferably the ' the liquid is maintained at a temperature of 150 to 225° F., preferably 185 to 195° F. The treat ment is continued for about 10 minutse to 2 hours, preferably one-half hour, after. which the excess of the treating liquid is separated from the ?ber, such as by centrifuging. Following this, 10 formaldehyde vapor. A‘ process of treating spun _ the ?ber may be placed under a vacuum and as ?ber with formaldehyde is described in copending ?ber after spim'ling is soaked in one or more _ formaldehyde containing baths and then washed and dried. Alternatively it may be treated with much of the treating liquid vaporized as pos sible. application Serial Number 417,024, ?led October 29, 1941, but other processes may be used. The protein may be any alkaline-dispersible ' The proteinaceous ?ber at the time it is intro- - duced into the treating ‘solution preferably should 15 have a moisture content of between 3 to 6%. The moisture in the ?ber reacts with a portion of the acetic anhydride to form acetic acid. However, it is a characteristic of the ?ber that it absorbs acetic acid, and the amount of acid 20 formed by this reaction is absorbed in the ?ber when the acetic acid concentration is maintained within the above de?ned critical limits. When the ?ber 'is removed after the conclusion of the acid-coagulable protein. The protein from milk, termed animal casein, and the protein from soy‘- ' beans, often referred to as vegetable casein, may be used advantageously and these materials are included in the generic designation of casein as used herein. Other proteins, such as those ob tainled from peanuts, seeds, hair, etc., may be use . The process of the invention is simple to "op crate, and may be practiced in a continuous semi process, it carries with it acetic acid equivalent 25 continuous or batch operation. It requires a to that formed by the reaction of the water with minimum' of materials, and temperatures that the acetic anhydride. Before the next batch of are readily obtainable. It has the advantage of " ?ber is treated in the treating liquid, additional simplicity of operation as well as the production acetic anhydrlde is added to bring the concen of a superior ?ber. tration up to the desired amount. ‘Thus for each 30 An important advantage of the invention‘ re batch of ?ber it is necessary only to add acetic sulting from the control of the acetic acid con anhydride equal to that which combines with the protein and is converted to acid by reaction with the‘ water in the ?ber, together with an amount of solvent equivalent to that absorbed by 35 tent within the above critical limits during the acetylation is the rate of dye absorption. Not only may the ?ber produced in accordance with the invention absorb dyes which act on ,wool and resist non-wool dyes, but the ?ber may absorb When the moisture content is reduced to within the above range, the process is adapted for con the dye at about the same rate as does wool in suitably controlled dye baths. This is an im port-ant property, since it is important that a uni the ?ber or lost evaporation. , " tinuous re-use of the treating liquid as explained above. This does not mean that fiber with a 40 form product be produced insofar as dyeing prop- _ ’ higher or lower moisture content cannot be used. erties are concerned. In the dyeing of mixed Since it is very di?icult to dry the ?ber to a goods it is also important that the different ?bers moisture content of less than 3% without harm of the mixture should all be the same shade as ing it, there will be few, if any, occasions to prac the result of treatment for a given length of time tice the process with a ?ber of a lower moisture 45 in the dye bath. If one of the ?bers, for example content. It is possible to treat a ?ber with a a synthetic proteinaceous ?ber, absorbs the dye higher moisture content but the amount of acetic at a faster or slower rate than another ?ber, acid formed by reaction of this amount of mois the dyed synthetic ?ber will be darker or lighter, ture with acetic anhydride is in excess of that respectively, than the natural wool dyed there which is absorbed by the ?ber and removed with 50 with. It is entirely unobvious that the concen it when the acid concentration is within the above tration of acetic acid, which is not an acetylat critical limits. Under the circumstances it is ing agent itself, rather than the concentration _ necessary to start with a treating liquid. having of acetic anhydride, should a?ect and control the an amount of acid, so that the acid produced in dyeing properties of the ?bers. the treatment, which is in excess of that ab 55 The process is subject to the variation in ma sorbed by the ?ber, brings the acid concentra tion of the treating liquid within the critical terials and conditions described herein, and all invention does not exclude the use of the same. range of 150° to 225° F., said treating liquid com prising an organic solvent inert with reference of the same are included in the invention as are range. If the treating liquid is to [be re-used for within the following claims. ' treating more ?ber of higher moisture content, I claim: it is necessary to neutralize the excess acid. 60 1. A process of treating a synthetically formed After the ?ber is removed from the treating protein-base ?ber produced by shaping into ?ber solution, it is washed thoroughly with water and form an alkali-soluble acid-coagulable protein the acetic acid absorbed in the ?ber is washed comprising casein and treating it with formalde out, leaving the ?ber relatively free from acid. It is unnecessary to use neutralizing or other 65 hyde, which process comprises treating said ?ber while having a moisture content of about 3 to 6% Q‘ basic ingredients in the wash water, although the The protein ?ber to be treated in accordance with the invention is made by dispersing the pro in a treating liquid at a temperature within the‘ ‘ _ to the ?ber and the ingredients contained in the _ tein in water with an alkaline material, such as 70 liquid and containing about 5 to 15% acetic anhy caustic, following which the dispersion is spun dride and about 5 to 7% of acetic acid, the tem perature and the amount of acetic anhydride tain a tanning agent. A process, which may be within the above ranges being selected with refer used is described in co-pending application Serial ence to each other and to the ?ber'being treated Number 309,028, ?led August 23, 1939, (which 75 so as to impart more desirable chemical prop ' into an acidic coagulating bath which may con 9,408,087 7 . erties to the ?ber without undue yellowing there . _ - _ 8 e _ in a treating liquid at a temperature of 150° to 225' r. for 10 minutes to 2 hours, ‘said treating liquid comprising an organic solvent inert with ‘ amount 0! acetic acid formed by reaction of the - - reference to the ?ber and the ingredients con tained in the liquidv and containing. about 5 to moisture in the ?ber with the acetic anhydride in 15% acetic anhydride and about 5 to 7% of acetic the treating liquid as a result of the speci?ed - oi’. and removing the ?ber from the treating liq uid having absorbed thereinl substantially the moisture content 01' the ?ber and the acid con- _ tent of the bath. a 2.’ A process of treating a synthetically formed ' protein base ?ber produced by shaping into ?ber form an alkali- luble acid-coagulable protein comprising casein and treating it with formalde hyde, which process comprises treating said ?ber while having a moisture content of about 3 to 6% acid, and removing the ?ber from the treating liquid having absorbed therein substantially the amount or the acetic acid formed by reaction oi ' the moisture in the ?bernwith the acetic anhydride in the treating liquid as a result or the speci?ed moisture content of the ?ber and’ the acid con . tent of the bath. FRANCIS CLARKE A'I'WOOD.