US2904386A

US2904386A - Foreign

Info

Publication number: US2904386A
Authority: US
Publication date: 1959-09-15
Anticipated expiration: 1976-09-15

Description

United States Patent O SURFACE CYANOETHYLATED CELLULOSIC TEX- TILE AND PROCESS OF MAKING THE SANIE WITH LIMTITED QUANTITIES OF REAGENTS Dmitry M. Gagarine, Pendleton, S.C., assignor to Deermg Milliken Research Corporation, near Pendleton, S.C., a corporation of Delaware No Drawing. Application March 31, 1955 Serial No. 498,450

24 Claims. (Cl. 8-1162.)

This invention relates to cyanoethylated cellulosic textile materials and to methods for their preparation.

. The advantages of cyanoethylated cottons and rayons are well known in the art. The properties of almost any cellulosic material having unsubstituted hydroxy. groups can be improved by cyanoethylation and cotton in particular can be advantageously modified by cyanoethylation since this modification results in increased dye receptivity, increased resistance to heat and greatly increased resistance to mildew and rot. Although the advantages of cyanoethylated cellulosic materials have been known for a number of years, the commercial production of such products has been extremely limited because there has been previously available no method by which cyanoethylated cellulose materials could be produced in quantity and at a competitive cost.

The prior art procedure for the cyanoethylation of cellulosic materials has generally comprised immersing acrylonitrile at the reflux temperature of the acrylonitrile- I water azeotrope. A large excess of acrylonitrile has been employed because it has been generally believed that this was necessary for level cyanoethylation anda product with a high nitrogen content. A dilute solution of the base has been customarily employed since it is known that with prior art procedures, concentrations of sodium hydroxide in excess of 5% result in the hydrolysis of the cyanoethyl groups introduced into the cellulose thereby giving a product with entirely different properties than desired and, in addition, it is well known that concentrated bases tendto result in an explosive polymerization reaction of the acrylonitrile.

The. prior art procedure has many severe disadvantages. In the first instance, the yield, judged by the amount of soluble base, ageing the thus treated fabric and thereafter acid scouring to remove the excess base. 7 The success of the new process is based upon a number of important discoveries. A first important discovery that makes possible the new process is that good penetration of the .acrylonitrile into the cellulose fibers is not only not necessary but is actually disadvantageous and that by limiting the penetration, a product with comparable or superior properties but with a lower nitrogen contact can be obtained. A secondimportant discovery is thata level cyanoethylation can be obtained even though the application of reagents is quite uneven if a suitable ageing step is provided. Still another important discovery is that when employed in amounts, less than about by weight of the cellulosic material, strong bases of concentrations greater than have heretofore been useable can be employed without hydrolyzing the cyanoethyl groups to any appreciable extent. The exact reason or reasons for this is not known but it has been found that according to the procedure of this invention, solutions containing up to 30% by weight of sodium hydroxide can be employed without any appreciable hydrolysis of the cyanoethyl groups if a proper reaction time is provided. A further important discovery upon which the process is based is that the percent yield materially increases, as a general rule, when the application of acrylonitrile is below about 40% and when the concentration of moisture in the fabric is below about 50%. V

The new process of this invention has numerous important advantages. A first such advantage is that the cyanoethylation can be largely limited to the surface of the cellulosic fibers and it has been found that it is largely the surface cyanoethylation which contributes desirable properties to cyanoethylated materials. Surface cyanoethylation achieved by this invention makespossible cellulosic materials with a lower nitrogen content displaying substantially all the advantages of prior art cyanoethylated cellulosic materials of much higher nitrogen content. The theory of the surface cyanoethylation according to the new process of this invention is that acrylonitrile is relatively insoluble in concentrated bases and the cellulosic material has a higher afiinity for the aqueous basic solution than for the acrylonitrile. Therefore, the aqueous basic solution is absorbed by the cellulosic fibers and, since there is no agitation of the fibers in the, presence of a large excess of acrylonitrile, the

. contact of the cellulose fibers with acrylonitrile is largely acrylonitrile reacted with the cellulose as compared to I the amount of acrylonitrile lost, for example, in the formation of byproducts, has been exceedingly low and it is believed that the highest reported yield prior to this invention was in the vicinity of 30% and that the average yield was in the vicinity of 10%. Such low yields materially add to the expense of the process. Still another severe disadvantage of the prior art procedure has been the hazard which accompanies the handling of fabrics containing unreacted acrylonitrile, for instance in the scouring operation. Further disadvantages include the necessity of recovering unreacted acrylonitrile from the fabric and of separating the byproducts from the unreacted acrylonitrile in the reaction vessel.

According to this invention the disadvantages of the prior art are overcome by a process which comprises apportioning onto a cellulosic material, containing free hydroxy groups, from about 3% to 40%acrylonitrile and at least about 5% but preferably less than 50% of an aqueous basic solution containing at least about 1% and preferably at least about 5% of a strong water limited to their outer surfaces. 7

A second important advantage of the new process of this invention is the high yields that it makes possible. Yields as high as have been obtained on occasion and yields in the vicinity of 60 to 70% are routinely observed. These high yields reduce the quantity of acrylonitrile consumed to such an. extent/that cyanoethylated materials can readily be prepared at an economical cost. v

Another important advantage of the new process is that it removes the hazard of handling fabrics or yarns containing unreacted acrylonitrile. In the process of this invention, ,all of the acrylonitrile placed on the textile material is generally either reacted with the cellulose or else is transformed into relatively non-toxic byproducts so .that the textile material can be safely handled during scouring without danger of injury to the personnel performing the operation.

Still another important advantage of the new process is that it eliminates the necessity of recovering unreacted acrylonitrile from the fabric or yarn and of separating large volumes of acrylonitrile from the byproducts of the reaction. When'acrylonitrile contacts an aqueous I base, part of it is transformed to dioxydipropionitrile in the prior art processes, where a large excess of acrylonitrile was employed, the acrylonitrile remaining in the reaction vessel had to be recovered from the byproducts by distillation. In the new process of this invention,

4 invention that the nitrogen content of the product be at least 0.5% which is approximately equivalent to 0.06 cyanoethyl group per anhydro-glucose unit as calculated by the following formula:

however, there is little or no excess acrylonitrile remaining after the reaction and dioxydipropionitrile is formed only on the textile material from which it can readily be removed.

7 Further advantages of the new process include its simplicity, its need for little or no complicated apparatus, its semi-continuous nature and its high production rate. As will be subsequently explained in detail, the only apparatus necessary for the efiicient performance of the new process is a pair of Scotch rolls (sometimes called kissing rolls) plus apparatus for winding the fabric or yarn and no provision. for heating is required. Still other advantages will become apparent from the detailed description of the new process which follows.

The new process can be employed on any textile material containing fibers formed of a cellulosic material having free hydroxyl groups although it is mostadvantageously employed with cotton since it is with this material that the greatest degree of improvement can be obtained. Other cellulosic materials which can be employed in the new process include viscose rayon and cellulose acetate that isincompletely esterified, although it will'be understood that, in the case of cellulose acetate, some of the ester groups may be hydrolized under the conditions of the reaction. The new process is 'best adapted for use with fabrics but if desired it can be adapted for use with yarns.

The new process can be employed for the production of materials in which the cellulosic fibers contain up to about 5 or 6% nitrogen but because the process makes possible surface cyanoethylation, prior art state ments, relating to the properties of a cyanoethylated cellulose with a given nitrogen content, do not apply. Cellulose fibers cyanoethylated according to the preferred procedures of this invention will generally contain at least 50% of thecyanoethyl groups in a surface layer with. a thickness equal to only 10% of the diameter of the fiber and if the proper conditions are employed, a surface layer equal in thickness to only about 5% of the diameter of the fiber will contain from 60 to 90% of the cyanoethyl groups as determined by cross-sectional dye tests. Because of this effect, a cyanoethylated cellulose fiber prepared by the preferred procedures of invention and containing as little as 0.5 nitrogen will display to a measurable extent the advantages of cyanoethylation, although it is generally advantageous to employ condition that will result in the fibers having from about 1 to 3% nitrogen. Fibers with thisnitrogerr con tent are comparable to prior art materials containing a A.W. of N X 100 wherein M.W. stands for molecular weight, A.W. stands for atomic weight, AGU stands for anhydro-glucose 1622+ (54X 0.06) X 0.5 14X100 This would indicate that the process of this invention could be satisfactorily conducted on a material comprisingcellulosic fibers containing as few as 0.06free hydroxy. group per anhydro-glucose unit, but it hasbeen discovered, as previously mentioned, that it is desirable for: at. least 50%- and preferably 60% of the anhydroglucose units in each fiber. to be disposed within a surface layer of the fiber having a thickness equal to approximately 10% of its diameter. In terms of. volume and considering the cellulosic fiber. to be round in cross section, at least 50% and preferably 60% of the cyanoethyl groups should be disposed. within 36% of the volume of the fiber in accordance with the following equation:

CEGs per AGUX of CEGs in outer layerX 100 percent volume in outer layerX 100 v I =CEGs per AGU in outer layer wherein symbols are as explained above. Substituting actual values:

As previously explained, for each cyanoethyl group per anhydro-glucose unit which is to be introduced into the cellulosic fiber, a corresponding equal number of free hydroxy groups per anhydro-glucose unitisrequired in much higher percentage of nitrogen and a surface cyanoethylated fiber prepared according to this invention and containing only about 2% nitrogen will, for example, generally display as much heat resistance as will a uniformly cyanoethylated fiber containing about 4% or more nitrogen.

It is well known that in the cyanoethylation of cotton and other cellulosic fibers, acrylonitrile reacts with the freehydroxy groups of the cellulose or cellulosic material to form cyanoethyl groups and that free hydroxy groups are necessary in order for this reaction to take place. It is also well known that the number of free hydroxy groups that must be-present depends upon the number of cyanoethyl groups that one. desires to add to the cellulosic material and, for example, if one wishes to add an average of 1 cyanoethyl group per anhydroglucose unit, the starting cellulosic material must have an average of at least one free hydroxy groupper anhydro glucose unit. It is desirable according to the present the starting. material, i.e. the cellulosic fibers which are to be cyanoethylated, and, in. view? of this and the calculations above, it .will be seen that the fibers-to cyano ethylat edshould have atleast 0.083 free hydroxyl group {teammate-glucose unit in order to produce'a product having a 0.5% nitrogen content with 50% of-the cyanoethyl groups disposed in a surface layer equal to not rn'ore than 10% .of the diameter of. the fiber, or at least 0.10 free hydroxy group .per anhydro-glucose unit in order to produce a product having a nitrogen content of 0.5% .withatvleast 60% of the cyanoethyl groups disposed in a surface layer of. the fiber equal in thicknessto 10% of the diameter of the fiber.

Theorder ofapplication of theaqueous. basic solution and. of the acrylonitrile is relatively immaterial and the same. product. appears .to be obtained regardless of which is applied first, In fact, by the use of a rnutual solvent, such as acetone or isop'ropyl alcohol, or by the use of an Hemulsion ofthe acrylonitrile. in the aqueous base; the. two reactants can. be applied simultaneously although..it.has been found t thatv simultaneous applica: tiori generally g stur in ibweg yields and thisr'nore than offsets the convenience of a single application. Generally, it is preferred that the aqueous base be applied prior to the acrylonitrile since this appears to more clearly limit the cyanoethylation to the surface of the cellulosic fibers and, as pointed out above, surface cyanoethylation has been found to be extremely desirable.

The method of application of the aqueous base and the acrylonitrile is relatively immaterial and, if desired, the reactants can be applied by hand, for example, with a sponge. Generally, however, it is advantageous to pro vide some type of simple apparatus for applying the reactants to the yarn or fabric and the preferred method of application comprises a Scotch roll for the application of each of the reactants. The Scotch rolls can be of any diameter, although a diameter of about 3 to 24" has been found to be convenient, and both rolls should have a smooth surface resistant to attack by strong alkalies. The roll surfaces are most conveniently of metal but can, if desired, be of any other suitable material such as polyethylene plastic. The reagent in each instance is applied to the surface of the roll at one point on its periphery by any suitable means such as by a wick or preferably by allowing the rollto dip into a volume of the reactant along its lower edge. The reagent is then carried in a thin layer on the surface of the roll to roll, preferably at its upper peripheral edge. It is generally advantageous to provide means for driving the roll atvarious speeds to thereby permit the amount of reagent; applied to the textile material to be easily adjusted by changing the peripheral velocity of the roll relative to the linear velocity of the. textile material passing in contact therewith. .If desired, a pair of superimposed Scotch rolls can be providedfor applying the reagent to opposite sides of the textile material but this is generally unnecessary since it has been found that the Suitable appa- .25 the fabric orjya'rn which is passed in contact with the The basic solution as well as the acrylonitrile can be applied at any desired temperature up to and including the boiling temperatures of the reagents although it is .generally preferred that both be applied at room temperature.

In some instances it might be desirable to refrigerate the acrylonitrile to lower its vapor pressure and in other instances, for example, when the base is applied immediately preceding the acrylonitrile, it appears to be slightly advantageous, from the point of overall yield, to applythe basic solution with the same at an elevated temperature, for example at a. temperature of from 1007 F. to 200 F. Generally,'however, room temperature for both reagents will be employed.

' Any base which is capable ofproducing a pH ofat least about 10- in 1% aqueous solution canbe employed in. the new process. Illustrative examples of suitable bases, are alkali metal hydroxides suchas soduim hydroxide and potassium hydroxide, quaternary ammonium bases such as tetramethyl ammonium hydroxide and phenyltrimethyl ammonium hydroxide, and alkali metal salts of weak acids such as sodium carbonate and tribasic sodium phosphate. The preferred base is sodium hydroxide. The aqueous solution of the base should have a concentration of at least about 1% by 'weight and for a faster reaction, higher nitrogen content in. the finished material and a greater degree of surface cyanoethylation,

a basic solution having a concentration of at least about 5% by weight should be employed. The upper limit of concentration is generallyfrom about 30% to by weight, depending on thebase employed, and it is seldom 6 advantageous to employ a basic solution having a concentration greater than about 15% by weight. Theinorganic bases exert an' undesirable swelling action=on cellulose when employed in concentrations above about 30% while concentrated solutions of some of the organic bases are actually capable of acting as solvents for cellulose. When employing sodium hydroxide under optimum conditions, it has been found that the optimum concentration for the basic solution is from about 8 to 10%. An unexpected advantage of the new process of this invention which may be obtained by employing a'sodium hydroxide solution having a concentration'within the preferred range of from 5 to 15% is that the chlorine retention ofithe cyanoethylated material, when washed in the presence of a sodium hypochlorite bleach, is generally no greater than that; of the untreated material. In fact, when the sodium hydroxide concentration is 9.4%, it hasbeen found that cyanoethylated cotton resulting from the new process is damaged approximately 10% less by washing with hypochlorite bleaches than is a control sample of untreated cotton. This is believed to be truly unexpected in vielw of the generaltendency of cyanoethylatedmaterials to be degraded by chlorine retention.

not be realized if the amount of base applied to the textile material is above about and the application of no more'than about 40%, based upon the weight of cellulose, is generallypreferred. On the other hand, the

amount of base employed should not be less than about 5% by weight, and the cyanoethylation is generally more uniform if the base is applied in amounts of about 10 to 15% by'weight. It is also a general rule that the concentration of the base can advantageously be decreased as the amount employed increases, butif the amount of base is below 40 or 50%, the rule need not be strictly observed and good results can be obtained, for example, by employing 40% of 4N NaOH or by erriploying 15% of 1N NaOH. When employing sodium hydroxide under optimum conditions, it has been found that'the optimum amount of the basic solution to be applied to the cellulose is from about 18 to 24% by weight. p

The amount of acrylonitrile which can be applied varies from about 3% to 40%, based on the 'dry'weight of the cellulose, with the preferred range being from about 6 to applied approaches about 10%, reaches a maximum at about 16% and decreases rather rapidly after the amount of acrylonitrile. applied becomes greater than about 20 to 30%. It will also be understood that, under these conditions, the amount of nitrogen which becomes fixed to the cellulose increases as the amount of acrylonitrile applied is raised to about 10% since below this figure, there simply is not enough acrylonitrile available to result in a high nitrogen content, even with overall yields of to A product containing Z'to' 4% fixed nitrogen, based on the weight of cellulose, will generally be obtained if all variables are selected to favor a near maximum overall yield and, since the cyanoethyl groups arehi ghly concentrated near the surfaces of the fibers, this results in an excellent product and there is generally little-or no advantage in sacrificing efficiency in an effort to obtain a product with a larger amount of fixed nitrogen.

Grea r unit ni y s.senera yrs b aii ss w a u fa ac ve a nt i applied ith t e a is lu o n r with h ac onit eh bas s sol t is pp first, the addition of a surface active agent thereto rethis n eatl in ea ed uni ormit u there is generally tt e .ad sda v ntasc i so empl a ive a nt in the a o r le If, however, the aqrylo nitrile is applied first, the addition of a surface active agent thereto is very advantageous and an additional sl ht m o eme can be b in by. also p yi a wetting agent in the basic solution. For addition to the basic solution, an anionic surface active agent has been found to generally give the best results with specific examples of suitable surface active agents being sodium laurel sulfonate andsulfated esters of unsaturated oils such as castor oil, For additiontothe acrylonitrile, it has been found that non-ionicagents are generally preferred with specific examples of suitable agents being isooxyethylene groups per molecule, and the reaction prodnot of the sorbitol ester of oleic acid with 50 moles of ethylene oxide. The surface active agents can advantageously be employed in amounts of from about .1 to 1 a d pr er b f m ab t t 2%- After the reagents have been applied to the cellulosic textile material, the material must be aged since it is this novel step which results in an even distribution of the reactants and since it is during this step that the acrylonitrile reacts with the cellulosic fibers. The ageing operation can be made more effective by folding, bunching orrolling the textile material into a compact mass so that the material forms a plurality of compact layers as this makes possible. transfer of the reagents from one layer to the other and thereby results in g reater uniformity. Formation of the material into a roll or cylindricall-y wound package has been found to be preferable to folding or bunching since the former results in an absence of greases, closer contact between adjacentlayers and is generally more convenient. The ageing operation is preferably performed with the textile material protected from the atmosphere which can be accomplished by placing-it in a closed container or, more conveniently, by wrapping it with a layer of material such as metal foil or sheet plastic material which is impervious to water and acrylonitrile vapors. This prevents local evaporation and also makes possible a more uniform temperature throughout the roll or the like of material.

. The time of ageing necessary for best results depends upon a number of factors including the temperature of the textile material, whether or not a surface active agent is employed in one or both of the reactants, whether or not the cellulosic material contains wax or other hydrophobie materials which might hinder the spread of the basic solution and the acrylonitrile, upon the concentration of the basic solution and upon the amount of the reagents applied; If the ageing time is too short, not only will the nitrogen content of the finished textile material be lower than might otherwise be obtained but unreacted acrylonitrile will be' retained on the textile material and the advantage of having a fabric for the scouring operation which is reasonably free of acrylonitrile will not be realized, On the other hand, if the ageing time is too long, it has been found that some of the cyanoethyl groups attached to the cellulose are hydrolized and the nitrogen content of the textile material is lowered. It can be seen, therefore, that a preferred time for ageing under all conditions-is one which is at least sufficient to result in the textile material having substantially no free acrylonitrilc at the end of the ageing period and insufficient to result in appreciable hydrolysis of the cyanoethyl groups attached to the cellulose in the textile material. It has been found that an ageing time of at least about 2 to 15 minutes, even when employing a minimum .of acrylonitrile and under conditions favoring affastreaction, should be allowed if one is to achieve the adbutylphenol polyoxyethylene ethers containing about 30 vantage ,ofa textile material substantially free of acrylonitrile for the scouring operation, and it is generally prefarabl to allow an ageing time of from at least about 20 minutes to one hour when employing more than a minimum amount of acrylonitrile. As a general rule, the ageing time should not be longer than about 30 or 40 hours, bu i h s e n oun t th an e e o ac lo ile a minimum amount of alkali and under conditions favoring a slow reaction, an ageing time of 70 hours or more can be employed without excessive hydrolysis of the cyanoethyl groups attached to the cellulose. Under near optirnum conditions, the optimum ageing time appears to be about 30 minutes to 6 hours.

A procedure which is exceedingly advantageous in some instances comprises applying to the fabric or the like, before the ageing operation, an acid forming or liberating eompound which serves to slowly neutralize the base during the ageing operation. This makes possible the elimination of the difference in ageing time which would otherwise exist for the first part and the last part of the material to which the reagents are applied, and also makes it possible to eliminate the timing of the ageing operation. Compounds which can beapplied for this purpose include esters of inorganic acids such as tricresyl phosphate and dibutyl sulfate, organic esters such as methyl formate and ethyl acetate, compounds, such as methyl chloropropionate, which down to give both an organic and an inorganic acid, and compounds, such as formaldehyde, which undergo an oxidation-reduction to give an acid. Such compounds should be employed in amounts at least suificient to theoretically result in the neutralization of at least about one-half the alkali in the textile material and preferably in an amount which is approximately stoichiometrically equivalent to the alkali. If the compound is employed in too large an amount, it dilutes the reactants unnecessarily so that it is seldom advantageous to employ quantities greater than two or three times the amount that would betheoretically necessary to neutralize the alkali in the textile material. In most instances the acid forming compound can most conveniently be applied by 'additionto the acrylonitrile, although, if desired, it may be applied in a separate operation.

The temperature of the textile material during the ageing step is relatively immaterial and best results are generally obtained by simply allowing the temperature to seekits own level. The reaction is exothermic and if the textile material is formed into a compact mass at room temperature, the temperature of the mass will rise within about 5 to 10 minutes to a temperature of from about 35 to 70 C. depending upon the size of the roll or the like and other factors. Of course, the rate of reaction increases with increasing temperatures and, if desired, external heat can be applied but it should be remembered that the acrylonitrile-water azcotrope boils at approximately 70 to 72 C. so that if the temperature is' raised rapidly above this figure and a large amount of acrylonitn'le has been applied, there is apt to be a loss of reactants.

If'one desires tomake the process fully continuous, there is at least one type of batching' apparatus which can conveniently be employed for the ageing operation, which apparatus is known as the Bentler Continuous Batching Chamber and is available through the Nova Chemical Corporation of New York, New York. This piece of apparatus simply comprises a pair of rolls on which a considerable length of material is continuously stored while allowing a running length of material to be continuously fed into the batching chamber and continuously withdrawn therefrom.

The primary ageing operation should be conducted after both reagents have been applied but in some instances improved results can be obtained by also ageing thev textile material between the steps of applying the two reactants. This is particularly true if the basic solution is applied first since ageing of the textile material after the addition of the basic solution and before the application of the acrylonitrile permits the basic solution to become uniformly distributed throughout the tex tile material before the cyanoethylation reaction is initiated and this, in some instances, tends to give a more uniform cyanoethylation and a higher yield. 'I'his ageing operation, if it is to be conducted, can conveniently be performed in the same manner as the final ageing operation described above. A period of one or two hours is generally most satisfactory, but the material may be aged for as long or as short a period as desired. After ageing the textile material in the presence of the base and acrylonitrile, it should be scoured to remove excess base unless a subsequent finishing step is to be performed in which a basic fabric is an advantage or in which the basic nature of the fabric is eliminated without interfering with the processing step. Of course, if the self-neutralizing procedure described above is employed, the fabric is not highly basic after the ageing step but the scouring operation is still advantageous to remove the salts and byproducts of the reaction. The scouring step can be performed in any conventional manner and if a proper ageing time has been employed, the cloth will contain no acrylonitrile so that no special precautions are necessary. For neutralizing the excess base in the textile material a dilute solution of any common acid can be employed although acetic acid solutions are generally preferred. Other acids which may be used include hydrochloric, sulfuric and formic acids.

The invention will now be illustrated by the following specific examples in which all parts are by weight unless otherwise indicated:

Example I A length of desized and mercerized cotton material weighing 2.5 pounds per yard is passed successively over a pair of stainless steel rollers having their surfaces slightly dulled by polishing lwith fine sand paper. The rollers, in each instance, are approximately 10 cm. in diameter (in large scale production, larger rolls having, for example, a diameter 8 to 24 inches are generally preferred) and are positioned approximately 4 inches apart. The cotton cloth is guided so that it is in contact with the upper peripheral edges of each of the two rolls through an arc, in each instance, of approximately 20 and is given a linear velocity of approximately 40 feet per minute. The lower peripheral edge of the first roll is allowed to contact, through an arc of about 90, a solution of 10% sodium hydroxide, containing'2% sodium 2-ethylhexyl sulfate as a wetting agent, and the roll is driven so that its upper surface is moving in the same direction as the cloth. The rate of rotation of the rollis adjusted so that there is deposited on the cloth about 20% by weight of the basic solution which generally requires that the roll have a peripheral velocity approximately 30% less than the linear velocity of the cotton material passing in contact therewith. The lower peripheral surface of the second roll is positioned in a quantity of acrylonitrile through an arc of approximately 90 and is driven in the same manner as the first roll to result in there being deposited on the fabric approximately 16% by weight of acrylonitrile. This generally requires that it be rotated at such a rate that it has a peripheral velocity approximately 20% greater than the linear velocity of the cotton material. It will be seen that with the rollers placed so closely together, the acrylonitrile is applied only a fraction of a second after the application of the sodium hydroxide. Following its contact with the second roller, the cotton material is tightly wound into a roll which, as soon as possible after the application of the reagents, is wrapped in a sheet of vinyl plastic and stored at room temperature for 18 hours. It is known that the temperature within the roll 'a'ises due to the exothermic reaction but it is not necessary to control the temperature of the cloth within the roll. After the ageing operation is completed, the roll of'material is unwound and washedin a 2% acetic acid solution containing 0.1% of dodecyl benzene sulfonic acid as a wetting agent'and is thereafter rinsed in clear water and dried. I

This example represents the presently preferred procedure of application and illustrates the presently preferred quantities and concentrations of reagents. A higher yield can generally be obtained by ageing the fabric between the application of the base and the application of the acrylonitrile but the increased yield is generally insufiicient to offset the added cost of an intermediate ageing operation. The above example has been repeated many timesand a product is generally obtained having a nitrogen content of from about 2 to 4%, based upon the weight of cellulose, with an overall yield, based upon acrylonitrile consumptiomof from 35 to 65%. The variations in yield are believed to be due to the eifect of variables which have not as yet been fully investigated such as the temperature of the sodium hydroxide at the time that it is applied to the fabric, the condition ofthe fabric at the time of the application and the size of the roll during the ageing operation. It is probable that each of these factors will affect the yield to a slight extent and this would account for the range of yields which-has been experienced. I

Instead of employing the first roller for the; application of sodium hydroxide, as in the, above example, the first roller can be employed for the application of acrylonitrile and the second roller used for the application of soduiin hydroxide. If approximately 1 to 10% of a nonionic surface active agent, such as a mixture of isobutylphenol polyoxyethylene' ethers containing about 30 oxyethylene groups per molecule, is added to the acrylo 'nitrile bath, the results obtainable by this modified procedure arefully comparable to those obtainable by the procedure of the above example. Likewise, instead of applyingthe reagents by means of rollers, they can be atomized onto the fabric by means of a sprayer but this is generally not advantageous since it results in a greater loss of acrylonitrile by vaporization. It is also possible to substitute other basic solutions for the sodium hydrox ide solution employed above and one can, for example,

substitute a 10% potassium hydroxide solution containing 4% of Z-ethylhexylSodium sulfate as a wetting agent, or a 10% solution of trimethyl phenyl ammonium hydroxide containing 2% of 2-ethylhexyl sodium sulfate as a wetting agent, with comparable results Example II A yarn end from a fabric cyanoethylated according to the procedure of Example I is placed in the slot of a Hardy thin cross sectioning device and the protruding ends of the yarn cut with scissors as close to the plate as possible. The cut' ends of the yarn are then coated with nitrocellulose lacquer (Neg-O-Lac) and the lacquer allowed to dry. The protruding parts of the yarn are then removed with a blade so that both ends of the yarn are flush with the plate of the sectioning device and .the nitrocellulose lacquer is again applied. The apparatus is then adjusted to give a section of the yarn approximately 5 to 10 microns in thickness which is placed on a glass slide and covered with one drop of water. The section is then stained with a 5% solution of Pontacyl Wool Blue BL (color index No. 833) and after one minute the section is removed from the slide with forceps and rinsed inwarm water to remove excess dyestuff. The section is then'mounted on a glass slide in water and examined with a projection microscope. The projection clearly shows that in each of the fibers, from 60 to of the color is in a surface layer extending around the periphery of the fiber and having a thickness of only about 5% of the'diameter of the fiber and that the cen:

11 tral' portion of the fiber is stained only a very light" blue. The procedure is repeated with an untreated cotton yarn and the cross sectionis found to be completely white indicating that the dyestufi attaches only to the cyanoethyl groups in' the cellulose fibers;

In place of the Pontacyl W001 Blue BL employed above, any otheracid dyestufl can'be substituted and m place'of making a visual determination as to the-distribution of dyestu'fi, one can employ any other recognized quantitative technique.

Example 111 Example I is repeated except that the second roll is allowed to contact a mixture of acrylonitrile and methyl acetate, containing by weight of the ester, and the rotation of the roll is adjusted such that the acrylonitrileester mixture is applied inan amount equal to about 18% of the weight of the cellulose in the fabric, which generally requiresthat the roll have a peripheral velocity approximately 10 feet per minute greater than the linear velocity of the fabric passing in contact therewith. Also, instead ofageing only 18 hours, the fabric is aged 200 hours, since it is the purpose'of the ester to neutralize the excess sodium hydroxide and to thereby permit an ageing periodof an indefinite length. The results obtainable by the procedure of this example are fully comparable to-those obtainable by the procedure of Example I.

In place of the methyl acetate employed above, one can, withsatisfactory results, substitute an equal weight of ethyl acetate, ethyl formateor tricresyl phosphate.

Example IV v Y A plurality-of samples of bleached, mercerizedi and scoured poplin materialare passed over a Scotch roller partially immersed in a sodium'hydroxide solution containing 2% sodium 2-etl1y1hexy1' sulfate as a wetting agent, and-the percentage pickup of sodium hydroxide is measured by the increase in weight. Provision is made for varying the peripheral speed of the roll relative to the linear speed of the fabric so that the amount of solution applied can readily be adjusted to any desired value. The cloth is formed into a tight roll, immediately following its contact with the surface of the sodium hydroxide applying roller, and is thereafter, as soon as possible, wrapped in a sheet of vinyl plastic material and allowed to age at room temperature for approximately 2 hours. At the end of this ageing operation, the material is unwrapped and passed over a second Scotch roller having its lower edge immersed inacrylonitrileandthe pickup again measured by the increase in weight. The acrylo nitrile treated samples are again formed into a tight roll and wrapped with a sheet of vinyl plastic material and aged at room temperature. After ageing, the samples of material are washed in a 2% acetic acid solution and rinsed with clear water after which they are dried and the nitrogen content thereof determined. The results ofa few of many tests conducted by this procedure are given in the following table:

'Having thusdescribed my invention, what I desire to claim and secure by Letters Patentis:

' 1. A method for cyanoethylating textile materials comprising cellulosic fibers in which the molecules of cellulosic materialhave an average of at least 0083- free hydroxy groupper anhydro-glucose unit, which cornprises apportioning onto the textile material from about 12 3 to 40%, based upon the weight of the cellulosic material, of liquid acrylonitrile and from about 5 to based upon the weight of cellulosic material, of a liquid aqueous solution of a base capable of producing a pH of at least 10 in 1% solution, saidbasic solution having a concentration of base of from about 1 to 40% by weight of said basic solution, and maintaining said textile material in contact with aqueous basic solution and unreacted acrylonitrile apportioned thereon and entrained thereby until it has a combined nitrogen content of from about 0.5% to 6% due to chemical reaction with acrylonitrile, the total amount of liquids applied by said apportionment and in and on said textile material during said reaction being equal to from 8 to 140% of the weight of said cellulosic material, said total amount of applied liquids being below the maximum amount capable of being absorbed and adsorbed by said cellulosic material.

2. The method of claim 1 wherein the base is sodium hydroxide and the amount of basic solution applied is from about 5% to about 50% by weight of the cellulosic material.

3. A method for cyanoethylating textile materials comprising cellulosic fibers in which the molecules of cellulosic material have an average of at least 0.083 free bydroxy group per anhydro-glucose unit, which comprises apportioning onto said cellulosic textile material from about 3 to 40%, based upon the weight of cellulosic material, of liquid acrylonitrile and from about 5 to 100%, based upon the weight of cellulosic material, of a liquid aqueous solution of a base capable of producing a pH of at least 10 in 1% solution, said basic solution having a concentration of base of from about 1 to 40% by weight of said basic solution, and thereafter placing said textile material, containing entrained reagents apportioned thereon, in a multi-layered configuration with adjacent layers in intimate contact with each other, and retaining said textile material in said configuration until it has a combined nitrogen content of from 0.5% to 6% due to chemical reaction with entrained acrylonitrile, the total amount of liquids applied by said apportionment and in and on said textile material while in said multi-layered configuration being equal to from 8% to 140% of the weight of said cellulosic material, said total amount of applied liquids being below the maximum amount capable of being absorbed and adsorbed by said cellulosic material.

4. A method for 'cyanoethylating the cellulose fibers in a fabric containing such fibers which method comprises apportioning onto said fabric from about -3 to 40% by weight of liquid acrylonitrile, based upon the weight of the cellulose in said fabric, and from about 5 to 70%, based on the weight of cellulose, of a liquid aqueous solution of a base capable of producing a pH of at least 10' in 1% solution, said aqueous basic solution having a concentration of base of about 1 to 30% by weight of said basic solution, placing the fabric, containing unreacted reagentsapportioned thereon, in a multi-layered configuration and ageing said fabric in said configurationfor a time sufficient to result in said cellulose fibers having a nitrogen content of from about 0.5% to 6% by weight due to reaction with entrained acrylonitrile, the total amount of liquids applied by said apportionment and in and on said fabric while in said multi-layered configuration being equal to'frorn 8% to of the weight of said cellulose fibers, said total amount of applied liquids being below the maximum amount capable of being absorbed and adsorbed by said fabric.

5. The method of claim 4 wherein said base is sodium ,aaqss s 8. The method of claim 7 wherein said fabric is placed into a multi-layered configuration and aged to perihitthe basic solution to become evenly distributed before the acrylonitrile is applied.

9. The method of claim 4 wherein said aqueous basic solution is applied immediately preceding the acrylonitrile.

10. The method of claim 4 wherein said fabricduring ageing is tightly enclosed to prevent local evaporation of the reagents.

11. The method of claim 10 wherein the enclosure is accomplished by wrapping said fabric, while in said configuration, With a sheet of vinyl plastic which is impervious to water and acrylonitrile vapors.

12. The method of claim 4 wherein there is addition ally apportioned onto said fabric, before the ageing operation, a compound which, in the presence of a base, slowly liberates an acid, whereby the excess base in said fabric is at least partially neutralized during the ageing operation.

13. The method of claim 12 wherein the acid liberating compound is added to the acrylonitrile and the resulting mixture apportioned onto the fabric.

14. The method of claim 13 wherein said acid liberating compound is methyl acetate.

15. A method for the cyanoethylation of a textile fabric comprising cellulosic fibers in which the molecules of cellulosic material have an average of at least 0.083 free hydroxy group per anhydro-glucose unit, which method comprises apportioning onto said fabric from about 15 to 50%, based upon the weight of said cellulosic fibers in said fabric, of a liquid aqueous sodium hydroxide solution having a concentration of base of from about to 15 by weight of said sodium hydroxide solution, subsequently apportioning onto said fabric from about 6 to 30% liquid acrylonitrile, based upon the weight of said cellulosic fibers, said apportioning of acrylonitrile being effected by contacting said fabric with a thin layer of liquid acrylonitrile, forming said fabric, containing entrained reagents apportioned thereon, into a tightly wound roll, enclosing said roll to prevent evaporation of the reagents, and ageing said roll while in an enclosed condition for from about 20 minutes to 40 hours and until said cellulosic fibres have a combined nitrogen content of from about 0.5% to 6% due to chemical reaction with acrylonitrile, and thereafter scouring said fabric to remove excess base, the total amount of liquids applied by said apportionment and in and on said textile fabric while in said tightly wound roll being equal to from 21% to 80% of the weight of said cellulosic fibers, said total amount of applied liquids being below the maximum amount capable of being absorbed and adsorbed by said fabric.

16. The method of claim 15 wherein said sodium hydroxide solution contains from 1 to of a non-ionic wetting agent which is surface active and which is effective in sodium hydroxide solution.

17. The method of claim wherein said sodium hydroxide solution and said acrylonitrile are apportioned onto said fabric by passing the same into contact with the upper surface of a first roll having its lower peripheral edge immersed in a quantity of said basic solution, and immediately thereafter passing said fabric into contact with the upper surface of a second roll having its lower peripheral edge immersed in a quantity of acrylonitrile.

18. A method for the cyanoethylation of a cotton fabric which method comprises apportioning onto said fabric from about 15 to 50%, based upon the weight of cotton, of an aqueous sodium hydroxide solution having a concentration of base of from about 5 to 15% by weight of said sodium hydroxide solution, said sodium hydroxide solution containing from about 1 to 10% of an anionic surface active wetting agent which is effective in sodium hydroxide solution, immediately thereafter apportioning onto said fabric fnom about 6 to 30% liquid acrylonitrile, based upon the weight of cotton, said apportioning of sodium hydroxide solution and said apportioning of acrylonitrilebeing. accomplished by contacting said fabric with thin layers, respectively, of said sodium hydroxide solution and said liquid acrylonitrile, forming said fabric into a tightly wound roll and enclos ing said roll to prevent local evaporation of reagents, ageing said roll, while in an enclosed condition, from about 20 minutes to 40 hours and until said cotton has a combined nitrogen content of from about 0.5% to 6% due to chemical reaction with acrylonitrile, and thereafter scouringsaid fabric to remove excess base, the total amount of liquids applied by said apportionment and in and on said fabric while in said tightly wound roll being equal to from 21% to of the weight of said cotton, said total amount of applied liquids being below the maximum amount capable of being absorbed and adsorbed by said fabric.

19. A textile material comprising fibers of partially cyanoethylated cellulose with a nitrogen content, due to cyanoethyl groups, of from 1% to 4% by weight, said fibers having, in each instance, at least about 50% of the cyanoethyl groups located in a surface layer of the fiber which has a thickness equal to not more than about 10% of the diameter of the fiber.

20. A textile material as in claim 19 wherein said fibers, in each instance contain at least about 60 to of the cyanoethyl groups in a surface layer of the fiber which has a thickness equal to not more than about 5% of the diameter of the fiber.

21. A method for cyanoethylating a textile material comprising cellulosic fibers selected from the group consisting of cellulose fibers and cellulose acetate fibers having at least 0.10 free hydroxy group per anhydroglucose unit, which comprises uniformly distributing on said textile material from about 3% to 40%, based upon the weight of cellulosic material, of liquid acrylonitrile and from about 5% to based upon the weight of cellulosic material, of a liquid aqueous solution of a base capable of producing a pH of at least 10 in 1% solution, said basic solution having a concentration of base of from 1% to 40% by weight of said basic solution, and maintaining said textile material in contact with aqueous basic solution and unreacted acrylonitrile apportioned thereon and entrained thereby until said cellulosic fibers have a nitrogen content, as a result of cyanoethylation, of from 0.5% to 6% by weight, the total amount of liquids applied by said apportionment and in and on said textile material during said reaction being equal to from 8 to of the weight of said cellulosic fibers, said total amount of applied liquids being below the maximum amount capable of being absorbed and adsorbed by said textile material.

22. A method according to claim 21 wherein said textile material, following the application of said base and said acrylonitrile, is aged for a period of from two minutes to 70 hours.

23. A method according to claim 22 wherein said textile material is a fabric and said ageing operation is conducted with said fabric in a multi-layered configuration with adjacent layers of said fabric in intimate contact with each other.

24. A method for cyanoethylating a cotton textile fabric which comprises apportioning onto said fabric from about 6% to 30%, based upon the weight of cotton, of liquid acrylonitrile and from about 15% to 50%, based upon the weight of cotton, of a liquid aqueous solution of sodium hydroxide having a concentration of base of from 5% to 15% by weight of said sodium hydroxide solution, forming said fabric, containing entrained reagents, into a multi-layered configuration with adjacent layers of said fabric in intimate contact with each other, and retaining said fabric in said multi-layered configuration for a period of from 15 minutes to 70 hours and until said fabric has a nitrogen content of from 1% to 4% by weight due to reaction with entrained acrylonitrile, the

1.5 a total amount of liquids applied by said apportionment and-in and on said textile material during said reaction. being equal to from 21% to 80% of the weight of. said cotton fabric, said total amount of applied liquids. being below the maximum amount capable of being absorbed and adsorbed by said fabric.

References Cited in the file of this patent UNITED STATES PATENTS Stallings Nov. 27, 1945 16 Stallings June 14, 1949 Weisberg Nov. 22, 1955 Compton Mar. 26, 1957 Compton Mar. 26, 1957 FOREIGN PATENTS Great Britain June 2, 1947 OTHER REFERENCES 63 and 88.

Dual: Textile Res. Jour., March 1955, pp. 246-253.

Claims

1. A METHOD FOR CYANOETHYLATING TEXTILE MATERIALS COMPRISING CELLULOSIC FIBERS IN WHICH THE MOLECULES OF CELLULOSIC MATERIAL HAVE AN AVERAGE OF AT LEAST 0.083 FREE HYDROXY GROUP PER ANHYDRO-GLUCOSE UNIT, WHICH COMPRISES APPORTIONING ONTO THE TEXTILE MATERIAL FROM ABOUT 3 TO 40%, BASES UPON THE WEIGHT OF THE CELLULOSIC MATERIAL, OF LIQUID ACRYLONITRILE AND FROM ABOUT 5 TO 100% BASED UPON THE WEIGHT OF CELLULOSIC MATERIAL, OF A LIQUID AQUEOUS SOLUTION OF A BASE CAPABLE OF PRODUCING A PH OF AT LEAST 10 IN 1% SOLUTION, SAID BASIC SOLUTION HAVING A CONCENTRATION OF BASE OF FROM ABOUT 1 TO 40% BY WEIGHT OF SAID BASIC SOLUTION, AND MAINTAINING SAID TEXTILE MATERIAL INCONTACT WITH AQUEOUS BASIC SOLUTION AND UNREACTED ACRYLONITRILE APOORTIONED THEREON AND ENTRAINED THEREBY UNTIL IT HAS A COMBINED NITROGEN CONTENT OF FROM ABOUT 0.5% TO 6% DUE TO CHEMICAL REACTION WITH ACRYLONITRILE, THE TOTAL AMOUNT OF LIQUIDS APPLIED BY SAID APPORTIONMENT AND IN AND ON SAID TEXTILE MATERIAL DURING SAID REACTION BEING EQUAL TO FROM 8 TO 140% OF THE WEIGHT OF SAID CELLULOSIC MATERIAL, SAID TOTAL AMOUNT OF APPLIED LIQUIDS BEING BELOW THE MAXIMUM AMOUNT CAPABLE OF BEING ABSORBED AND ADSORBED BY SAID CELLULOSIC MATERIAL.

19. A TEXTILE MATERIAL COMPRISING FIBERS OF PARTIALLY CYANOETHYLATED CELLULOSE WITH NITROGEN CONTENT, DUE TO CYANOETHYL GROUPS, OF FROM 1% TO 4% BY WEIGHT, SAID FIBERS HAVING, IN EACH INSTANCE, AT LEAST ABOUT 50% OF THE CYANOETHYL GROUPS LOCATED IN A SURFACE LAYER OF THE FIBER WHICH HAS A THICKNESS EQUAL TO NOT MORE THAN ABOUT 10% OF THE DIAMETER OF THE FIBER.