US1957301A - Fibrous material and process of treating same - Google Patents

Description

Patented May 1, 1934 FIBROUS MATERIAL AND PROCESS OF TREATING SAME Merwyn C. Teague, Jackson Heights, and Nehemiah H. Brewster, Brooklyn, N. Y., assignors to The Naugatuck Chemical Company, Naugatuck, Conn, a corporation of Connecticut No Drawing. Original application January 7,

1932, Serial N0. 585,334. Divided and this application February 13, 1932, Serial No. 592,846

2 Claims.

It is well known thatfabric materials coinposed of various types of associations of yarns may be treated with rubber in order to improve their physical properties. This rubber treatment, however, has heretofore been carried out in such a manner that the rubber component of the rubber-fabric association has beenreadily apparent to the eye and to the touch. For this reason it has been impracticable to use a large number of rubber treated fabric materials for the purposes for which these fabric materials are normally utilized when not rubber treated. Consequently it has heretofore been impossible to fully utilize the advantageous characeristios in physical properties imparted to various types of fabric material by the use of rubber. For instance silk materials have been rubber treated, yet theresultant product has possessed a distinct rubbery appearance and feel and has thus been rendered unsuitable for wearing apparel.

Probably the reason for the very apparent rubbery appearance and feel of rubber treated textile fabrics as at present manufactured is because of the quite appreciable amounts of rubber which have been incorporated therewith to form an impervious, water-proof structure, either distribute'd throughout the fabric structure or localized at the surface in the form of a coherent coating. Even when fabrics are impregnated or coated with what are considered very small amounts of rubberjn any of the various ways heretofore known we have found that there is between -50 percent of rubber associated with the fabric, this percentage being based upon thedry weight of the fabric treated.

This invention involves the use of rubber with various types of fabric material, particularly, fine fabrics adapted for use in wearing apparel, dra-' peries, upholstery, etc. By this invention the physical properties of such fabrics are greatly improved by methods involving a particular manner of applying rubber in relatively small amounts, considerably less than those above indicated, yet no patent rubbery appearance and feel is manifest, in fact the treated fabric material is in no way undesirably changed. A new field of application for rubber has thus been made available in that fabric materials heretofore not adapted for their normal uses if treated with rubber, may be so treated and rendered more suitable for the ordinary uses to which they are put.

The invention is applicable to line woven or knitted fabric such as silks, satins, woolens, lin- 5r ens, lisles, and finely'meshed cotton fabrics oi.

jersey cloth for garments. Other applications will more clearly appear from the following specification and claims.

The advantages to be derived by the use of the invention are various and vary in accordance with the specific application thereof. In all cases, however, fabric materials composed of yarn associations are increased in strength and wear resistance and the appearance of the fabric which has been treated in accordance with the principle of the invention is advantageously aflected in that the yarns appear to be more firmly knit or woven than do the yarns of untreated material and on close inspection give the effect of a quality fabric constructed of finer yarns more thoroughly twisted. fabric, however, is not deleteriously affected and it is impossible for anyone but an expert to perceive any evidence in rubber in the finished product. With silk and rayon there are additional advantages in the application of the invention in certain embodiments as the extreme lustre of this type of material may be softened and reduced without the application thereto of heavy metal salts as isthe common practice, and without increasing the twist in the single and plied yarns as has been proposed for this purpose (and consequently increasing the amount of materlal necessary to make any given article); on the contrary the incorporation of rubber in the manner herein set out adds a certain amount of body and rayon yarns are knitted, the application of 0 The normal appearance and feel of the 80 the invention greatly decreases the tendency of this type of material to run.

As a process, the invention is particularly advantageous over rubber treating processes heretofore known in that it provides for reducing the tack of the rubber treated material prior to the time it is taken from the rubber treating apparatus and led into or through subsequent processing apparatus. This results in great facility in handling.

The invention consists essentially in treating fabric material with dilute aqueous dispersions of rubber having compounding and modifying ingredients incorporated therein if desired, in a manner so that the rubber particles are uniformly distributed throughout the fabric and in and upon the component yarns. When the rubber particles have been completely distributed they are coagulated in situ, after which the excess aqueous bath, carrying rubber particles which have not become attached to the yarns and carrying other liquid and solid particles which have not become attached to the yarns or entrapped in the rubber coagula which have become attached thereto, is expressed from the fabric and thereafter the fabric is dried in the desired form. Coagulation of the rubber may be brought about by the utilization of heat or by chemical coagulants, the aqueous rubber dispersion may be modifield by various modifying agents and the fabric material may be simultaneously treated with scouring and dyeing agents, all of which will be hereinafter particularly described. The invention also consists in the novel product of the above described process.

In its preferred form the invention is carried out by the utilization of heat for the purpose of coagulating the rubber. As a specific example of the manner in which the invention may be accomplished by the use of heat as the coagulant, the following is exemplary. In this example, directed specifically to the manufacture of silk hosiery, the process is carried out as a complete fabric finishing operation, including scouring and dyeing the material as well as treating it with rubber:

Silk stockings in desired quantity are shaken loosely into mesh bags which are placed into the compartments of the suitable washing machine, for instance an American laundry machine or a Smith 8: Davis drum dyer. The machine is filled with cold water in an amount suificient to give approximately two gallons of water for every 'pound of silk. A good grade of soap for instance an olive oil soap or a rosin soap in the proportion of about one pound of soap on five dozen pairs of stockings (or about one pound of soap with every four pounds of silk) is added and the water is heated to boiling temperature, for instance by the use of steam. The machine is put into operation and the stockings agitated in the soap solution for a suitable time, say 15 to 25 minutes in order to scour the material and remove the natural gums from the silk fibers. If

- desired the scouring liquor may at this time be drained from the machine which may then be refilled with a dilute soap solution and heated. At this time there is added an aqueous dispersion of rubber in amount sufficient to give 18% rubber dispersion solids on the dryweight of the silk charged into the machine (but yielding a very dilute dispersion when intermixed with the treating bath), said dispersion being mixed, if desired, with about 5% (based on the dry weight of the silk) of soluble pine oil prepared by dissolving the pine oil in a small amount of boiling water, together with 5% glycerine on the same basis. A dye solution in the proportion of .01 lb. of dye to 1 lb. of silk is then added and the whole solution allowed to come to approximately 180 F. The dye may be any water soluble organic dye and is preferably composed of acid dye and 25% direct dye. For instance the above proportions of Cyanone R Blue from National Aniline & Dye Co. and Pontamine B from Du Pont Co. may be used in order to give the stockings a blue color. Heating is continued for a suitable interval, say 35 min. or for suflicient time to dye the stockings the required color and to coagulate the rubber upon the fibers of the silk. The time for this step is subject to wide variation depending upon a number of factors, including the amount of residual gum on the fibers, the pullingoff of the dye due to the elevated temperature, the type and color of the dye and the amount thereof. More dye may be added if necessary to match a given sample.

After the desired color is obtained and coa ulation completed, the liquid is drawn off and the stockings rinsed with cold water several times. After the last rinse'the stockings are removed and placed in a centrifugal or vacuum extractor and the residual liquor largely extracted, for instance to a point where no liquor can be wrung from the stockings by hand. They are then removed from the machine and placed on steam heated metal forms where they are left until dry, and, if suitable vulcanizing ingredients have been incorporated in the rubber dispersion, at least partially vulcanized. The forms may be coated with mineral oil, waxes or hydroscopic agents such as glycerine or soaps in order to facilitate putting stockings on the forms and stripping them therefrom. When dry they may be removed and stored until the vulcanization of the rubber is complete.

It should be noted that while aqueous dispersions of rubber having variable solids content are used, they in all cases are diluted with a considerable amount of water, so that the actual percent concentration as used is small. In this and the succeeding examples a' satisfactory concentration well under 10% is set forth, but it is obvious that higher concentrations may be used and the result, namely, of having a small amount of rubber in thefinished material, obtained by utilizing more efficient extracting or wringing apparatus for expressing excess aqueous materials as well as solid particles which have not adhered to or between the fibrous elements of the yarns or which have not been entrapped in the rubber coagula which have been distributed throughout the yarns. It is obvious also that if a large volume of water is used to treat a very small amount of material, the weight of the rubber used on the material may be large, yet the actual percentage concentration of the solution w1ll hkewise be small.

When vulcanization is carried out, it is probably commenced during or immediately after coagulation of the rubber in the bath and is given impetus on the heated form, yet is not complete until several days, perhaps as much as several weeks after the stockings are dried and removed. The time for complete vulcanization of course may vary depending upon the amount and kind of powerful accelerators of vulcanization used, the time for which and the temperature at which they are stored.

The following is exemplary of the aqueous rubber dispersion which may be used in-the preceding example:

Parts by This mixture is prepared in a state of aqueous dispersion by first adding the stabilizer to the latex, then solubilizing the: casein" with borax and adding the same to the mix and next preparing the vulcanizing ingredients in the form of a paste and adding them to the mix. The dispersion is preferably a natural one having a total solids content of about 30% but it may be diluted or concentrated as desired as by creamin centrifuging, heat concentrating, etc. The dispersion may be one of vulcanized latex or it may be an artificial dispersion made by known processes. Any of the above dispersions may of course be modified further than as indicated in the formula, for instance there may be added antioxidants, fillers, softening agents, gelling agents, etc.

With the rubber may be incorporated small amounts of carbohydrates such as dextrine, starches, industrial gum (Lakoe gum) Karaya gum, gum tragacanth, etc. together with emulsified oils to prevent stifiness.

Other variations in the illustrative formula above set out may also be made. For instance a suitable stabilizer is a product sold under the trade name Nekal whichis a condensation product of an aromatic hydrocarbon and an aliphatic alcohol in the presence of sulphuric acid but such .stabilizer may be replaced by other stabilizing materials or compounds. The accelerator may be any suitable organic accelerator or mixtures thereof. The casein may be omitted or replaced by other proteins such as blood albumin or egg albumin, glue, etc. which materials may also act in a stabilizing capacity; The borax may be replaced by ammonia or some other fixed alkali as sodium carbonate or sodium hydroxide in order to solubilize the casein. The sodium fluoride may be replaced by some. other germicidal agent. The glue used to stabilize the paste may be replaced by other colloidal material and the amount may be varied as desired for particular requirements. The pine oil indicated as being mixed with the dispersion may be omitted. The glycerine may,

if desired, be omitted. Other variations may be made without departing from the principles of the invention, for instance after dye has been added and the solution boiled, about 10% Glaubers salt may be added (based on the dry weight of silk), to fix the dye more permanently. A suitable wetting agent such as sulphonated mineral oil, maybe added at any time prior to coagulating the rubber.

Stockingstreated as above described are easily boarded-and stripped from the forms and manifest increased resistance to wear and increased bursting strength when tested 'on an apparatus similar to a Mullen tester. The resistance of the material to runs is greatly increased. In addition of textile materials in the form of an article, but may be applied to sheet goods or to fibrous ma terial in the form of yarns or cords or any other states of association. For example, the following treatment embodying heat coagulation has given advantageous results in respect to rayon fabric prepared in knitted state and in tubular form:

A suitable type of washing machine is charged with water into which is mixed a weak solution of soap, the fabric added and the machine operated to scour the fabric. There should be enough water to cover the rayon and allow it to be agitated in the bath with facility, the proportion of water being approximately two gallons for every pound of rayon to be treated. The washing step may be accomplished with the application of heat at say 180 F. and will require anywhere from one-half hour to an hour. After the scouring is complete the liquor is drained from the container and the fabric rinsed in fresh water, if desired, to remove the scouring ingredients, after which the machine is again filled with water in the same amount and heated as before. The drawing off of the scouring liquor may be omitted if desired. The next step is the addition of the rubber dispersion which may be of the type mentioned in the preceding example or to which an additional stabilizer such as sodium silicate may have been added, and added in the proportion of approximately 10% rubber dispersion solids on the dry weight of the material. With the rubber may be added a wetting agent such as sulphonated vegetable or mineral oil or Nekal in the proportion of l to 2% on the weight of the rayon. Sometimes it may be desirable to add 1 to 2% of glycerine or other hygroscopic agent to prevent excessive drying during intermediate steps of the process. In addition there is added at this time a small amount of dye (the amount depending upon the type of dye used) dissolved in water. It should be understood that by reason of the presence of a relatively large amount of water the effective concentration of the rubber dispersion is small despite the fact that rubber has been added in the proportion of 10% based on the dry weight of the material.

The solution is kept agitated and heated for approximately one-half hour at a temperature near boiling, by which time the dye is set and the rubber particles of the dispersion are coagulated and set in the fabric. It is desirable that the temperature at which this step is carried out be not too high nor sustained for too long a time as excessive heat conditions are injurious to rayon. It may be desirable to incorporate ammonia prior to this heat treatment in order to prevent premature coagulation of the rubber by mechanical agitation and in such case the ammonia is driven off during the heat treatment.

After the rubber and dye have been coagulated and set, the fabric may be removed, rinsed in cold water and the liquid extracted to a condition near dryness, after which the fabric may be dried in a hot air heater at approximately 190 F. for at least one-half hour, preferably longer. in order to speed up the vulcanization of the rubber.

Material which has already been dyed or material which is desired in its natural color or in its bleached or unbleached state may be treated in accordance with the princ'ples of the invention as above set out, the steps relating to scouring and dyeing being omitted. For instance a mixture of cotton and wool material, woven into a fabric in the form used as automobile upholstery, may be immersed in an amount of water sufiicient to immerse the same with facility, or in an apparatus known as a dyeing jig, an aqueous dispersion of rubber added, and the water heated to near boiling. The aqueous rubber dispersion is preferably compounded as in the preceding examples, and added in amount sufiicient to give 15% dispersion solids based on the weight of the dry fabric treated, but of course the effective concentration of the solution is small on account of the relatively large amount of water with which the rubber dispersion is intermixed. The fabric may be agitated or continuously passed through the jig or other apparatus to effect uniform and thorough saturation, during which the boiling is continued for a desired period, at least of sufficient duration to cause the rubber to coagulate on and between the fibres, after which rinsing, extracting and drying may be accomplished as hereinbefore set out.

The invention may be also practiced by the utilization of a chemical to bring about coagulation. The following is an example of the process wherein this type of coagulation is effected. Although heat is used in this embodiment, its utilization is largely for the purpose of fixing the dye and has no function as far as coagulation is concerned. This embodiment also indicates how the process may be carried out conjointly with the scouring of the fabric and the application of dye solutions thereto:

Silk stockings may be placed in a machine, scoured, dyed and treated with aqueous dispersionsof rubber in the same manner as above indicated up to the step where the heating is continued for the purpose of coagulating and fixing the rubber on the fibres. In the present embodiment at this point the heating need not be continued longer than is necessary to set the dye and the temperature need not go higher than F. which is usually sufficient for this purpose. At this time and after the desired color has been obtained, the rubber and associated solids are coagulated by the addition of a chemical coagulant which in this case may be a 5% solution of am monium or potassium alum. This coagulant can best be added in two or three portions with an interval of several minutes between each addition in order to get thorough distribution of the coagulant throughout the bath. The precise amount of alum solution can best be predicted by experiments since different latex compositions will contain varying amounts of ammonia or other alkali. The amount for a particular case, however, may be determined by adding the alum solution slowly until such time as the entire bath becomes and remains for a few minutes neutral or slighly acid since under these conditions the aqueous dispersion of rubber is precipitated to most effectively lock the rubber within the individual yarns or fibrous associations. Other coagulants or setting or agglomerating agents applied in liquid or vapor form may be used. These include acetic acid, acetone, alcohol, formaldehy'de, tannic acid or other weak acids, or dilute solutions of stronger acids. Electrolytes such as calcium chloride, calcium sulphate, aluminum sulphate or other soluble bivalent metallic salts such as those of barium, strontium or calcium.

When specific delustering effect on silken fabrics are desired there may be variations in the embodiment of.the process above described. For example if it be desired to obtain a final product of very dull appearance an adjustment should be made in the amount and type of soap in the bath and the amount of alum or other coagulant finally used so as to precipitate in situ, simultaneously with the rubber, the desired amount of insoluble soap. Suitable soaps for this purpose are olive oil, rosin or other fatty acid soaps. In some cases it may be desirable to use ammonium soaps of these fatty acids, in order to deposit fatty acids in the fabric by the decomposition of such soaps under the heat conditions of the process. The combined precipitation of such soaps and coagulation of rubber produces a more permanent delustering effect than many delustering processes now used and involving the use of heavy metal salts. On the other hand if it be desired to get the maximum advantage of the rubber present but without so much delustering effect, then just before the coagulant is added the dye and rubber dispersion bath may be drained from the container (having first made sure that a sufiicinet amount of the rubber dispersion is used to have the desired amount retained in the liquid held by the stockings), and fresh cold water added to approximately the same volume as before. In this way the excess of the soap is first removed before the coagulant is added and thus the rubber is precipitated in the yarn without the formation of a large amount of insoluble soap.

After the coagulation of the rubber in the fab ric the stockings are removed from the bath and wrung, as by a centrifugal extractor, to the de- 3 sired extent and then dried on forms in the usual Way.

As another example of the utilization of chemical coagulation in carrying out this invention,

the following is illustrative: This embodimentexemplifies a procedure designed specifically for the treatment of tubular knit rayon fabric like that indicated in the example involving the treatment of this type of material by the utilization of heat as a means of coagulation.

The fabric is placed in a textile dyeing machine commonly known as a jig or open dye kettle and the ends knotted together at the corners so that the fabric may be circulated in and out of the bath of the machine in the form of an endless belt. The container is charged with soap as indicated in the preceding example and the steps preceding coagulation, namely those of scouring, adding rubber dispersion, wetting agents, dyes and other ingredients carried out in the manner hereinbefore described in connection with rayon fabric. In this example a dye known as Sky Blue 68, obtained from the National Aniline and Dye Corporation of the General Dyestuffs Corporation is added to the aqueous bath in quantity sufiicient so that for each pound of fabric there is added one pound dye in solution made up in the proportion of 1 lb. of dye to 1000 of water. The machine is continued in operation for a further period and at a temperature sufficient to fix the dye. It should be understood that the quantity of material and other factors as hereinbefore referred to require a variation in the temperature of the dye bath and the times of agitation therein, although for rayon fabrics treated as above described the temperature range may be fixed between 110 F.

and 200 F. and the times of agitation fixed accordingly.

The material may now be treated with a chemical coagulant which may be in the form of a 5% solution of alum. This is most conveniently added in two or three portions with continued agitation. The amount of coagulant in this case may be ascertained as that sufficient to make and hold the bath slightly acid in reaction for a few minutes. The agitation of the fabric in the bath is preferably continued after the addition of the coagulant. In case it is desired to destroy or decrease the normal lustre to the rayon, this may be accomplished by adding a small amount of soap solution to the bath prior to adding the alum and in this way later form insoluble soap. Or there may be added an amount of some soluble barium salt such as some barium chloride just before the addition of the alum. In this way there is formed in situ an insoluble precipitate such as barium sulphate simultaneously with the rubber in and through the rayon yarns.

The aqueous bath may now be removed and the fabric thoroughly rinsed, the excess water then removed by wringing or extracting and this fol lowed by drying, say in a whirlwind dryer at 190 F. Other methods can of course be used for drying as will be apparent to oneskilled in the art.

Still another example of the commercial use of the invention embodying the step of coagulating by chemical means, is given in the following procedure used for the treatment of flat woven silk, such as satin fabric which has been previously scoured and dried in the usual manner. In this example of course the incorporation of a scouring agent in the treating bath is unnecessary and the process is illustrated as proceeding from the point where the clean satin is taken from a supply and charged into the treating apparatus. Into the usual jig type of machine such as usually contains say 300400 gallons of water during operation is introduced the desired amount of cold water, the silk fabric placed in the machine in the form of an endless belt, and the machine started to operate. An aqueous dispersion of rubber with or without a wetting agent is then added slowly into the bath during agitation. In this case the aqueous dispersion solids are added in the proportion of about 25-30% of the weight of the silk fabric but forming a dilute dispersion when intermixed with the water. At times it is desirable although unnecessary except for the purpose of removing the odor of rubber from the finished article, to add soluble pine oil, and glycerine, for the purpose of retaining moisture in the fabric pending drying, each in the proportion of 1% based on the weight of the dry fabric and added as described under the treat ment of stockings, noted above. The machine is operated for a time sufi'icient to thoroughly distribute the aqueous dispersion solids throughout the fabric and bath after which the temperature of the bath is increased over a period of approximately 10 minutes to about 180 F. During the heating is added the usual quantity of dye solution together with a small amount of soap such as olive oil soap. The machine is run for a suitable time, say 20 minutes at this temperature, at the end of which time the dye be-- comes more firmly fixed. The dispersed rubber solids are then precipitated or fixed in the fabric by the addition of logwood extract or other forms of fixing agents such as tannic acid. It has been found advisable to use more than the amount of logwood extract normally used in dyeing operations so as to make sure of sufiiciently setting the rubber solids. An alternative procedure of coagulation may be followed by using the normal amount of logwood extract to set the dye but to supplement its action of coagulating the rubber solids by the subsequent addition of another chemical coagulant such as an alum solution, a heavy metal salt, etc. The machine is continued running for say 20 to 25 minutes after the addition of the coagulant, after which the fabric is rinsed, extracted and dried.

Still another commercial use of this new process, as embodying the principles of chemical coagulation, is that of treating heavier fabrics such as wool or wool and cotton fabrics. The procedure noted with respect to treating this type of material by utilizing the heat coagulation embodiment of the invention may be followed, except the temperature need not be raised. That is to say the fabric is placed in a jig type of equipment and circulated in and out of cold or warm water. In this case the fabric has been previously secured and dyed and woven so as to produce a figure in the fabric. Instead of coagulating the rubber from aqueous dispersion by heating the bath, a coagulant such as alum is slowly added to the bath as described in the above examples until such time as the solution becomes and remains for a few minutes neutral or slightly acid in reaction. The fabric is agitated in the solution containing the coagulant for about 10 or 15 minutes for a period sufficient to insure coagulation of the rubber particlesin the position in which they have lodged, after which time the fabric is thoroughly rinsed, the excess water squeezed or extracted and the fabric dried.

It is of course understood that the process may be carried out by successively immersing the fabric to be treated in various baths. As a matter of practicability the embodiments hereinbefore exemplified have been described as involving a treatment of the material in one container, the various ingredients being added successively or concurrently depending upon the conditions in the particular case. As an example of the manner in which the process may be carried out by utilizing successive treatments, silk stockings which have been previously washed and dyed may be immersed in a water bath containing a wetting agent of the nature described in the preceding examples. After this the stockings may be taken out and immersed in a water bath containing a suitable latex composition, for instance one prepared as previously described. The bath may be heated to a temperature near boiling to coagulate the rubber, or the stockings may be taken from the bath and immersed in or contacted with a third bath containing dilute acid or other agglomerating material to coagulate the rubber. After coagulation the excess liquor is extracted and the stock ng is washed in the manner previously described.

We have found that in practically all cases the amount of dispersed rubber solids added to the treating bath and based on the dry weight of the fabric or fabric stocks will range from 3 to 30% but it should be understood that due to the large amount of liquid present in the treating bath the dispersion is actually of a very d lute naturethat is the total percent rubber solids in the aqueous bath is small. Consequently the principle of the invention may be observed to involve a treatment with a dilute aqueous dispersion of rubber which is quite different from present known treatments with rubber dispersions involving the application of the relatively thick and concentrated aqueous dispersion of rubber and resulting in rubber films or impregnations which distinct-1y alter the normal appearance and feel of the fabric treated. Materials treated in accordance with this invention possess no rubbery feel or undesirable stiffness or hardness. They do, however, possess improved physical characteristics which vary in a manner commensurate with the differcut physical characteristics of the fabrics themselves. The normal appearance and feel are not materially altered, in fact it is difiicult for anyone except an expert to note a difference between similar pieces of treated and untreated material. With silk and rayon, depending on the amount of rubber and associated insoluble precipitates, the changed nature of the material is most apparent as in these cases the normal lustre of the material is usually reduced. In all cases, however, close inspection reveals a yarn structure more closely associated than in untreated goods, and a firmer and smoother feel and more closely knit or woven construction is readily apparent to an expert. The strength and wearing qualities of the material is in all cases materially increased. With knitted fabrics the knit loops tend to hold themselves in position thus appreciably decreasing the tendency of this type of material to run where a loop in one course is broken. In general fabric materials treated in accordance with the invention manifest a natural appearing yarn structure in which upon close inspection with the aid of a microscope the structural elements (filaments, fibres, etc.) are more closely associated than in untreated material, the rubber particles being indiscriminately distributed between them, binding them together into a substantially unitary yarn structure and tending to hold the yarns in the shape they have assumed during fabrication. It may be that substantial particles of coagulated rubber becomes depositedbetween adjacent yarns and where this occurs it is obvious that a knitted or woven structure will be effectively and flexibly interlocked.

It will be observed that the process of this invention enables the use of as much stabilizing colloidal material as is desired to prevent premature coagulation of the rubber by mechanical agitation, and that such materials are largely removed by reason ,of the selective coagulating step and the succeeding extracting step. Only the rubber and some of the associated materials are coagulated, or entrapped in the coagula, leaving a considerable amount of water soluble constituents of the rubber dispersion freely suspended therein and subject to being washed out or wrung from the fabric by subsequent operations. The resulting coagulated rubber may be seen therefore to contain a less amount of water solubles than does the rubber in aqueous dispersion with which the fabric has been treated. It is apparent therefore that the advantages of using stabilizing colloids in the preparation and processing of the rubber dispersion used may be utilized, yet the disadvantages of having these colloids present in the'deposited rubber binder obviated.

Due to the more compact relation assumed by fibers or elements making up the individual yarns of which a knitted silk fabric is constructed, such as silk stockings, it is more diiiicult for a splinter,

fingernail or other sharp projection to catch on these fibers or elements thus reducing liability to run. Moreover, if a fiber or element does become caught and broken, the parts thereof will not easily become disassociated from the adjacent fibers or elements and this also tends toward the prevention or continuation of runs and the occurrence of pull threads. This same structural characteristic, namely the more firm and compact yet flexible relationship of the fibers or elements going into the individual yarns, greatly increases the resistance of a fabric to wear, probably because it reduces or eliminates friction between the component parts of the yarn. Whatever the reason, however, this characteristic has been definitely established, and with coarse woven cotton and wool upholstery fabric treated in accordance with the invention, wear tests have indicated an increased resistance to wear of several hundred per cent While in the foregoing the invention has been disclosed with respect to the utilization of natural or reclaimed rubber dispersed in an aqueous medium either as found naturally or compounded, or as manufactured artificially according to known processes, at least some of the advantages of the invention may be obtained by using syn thetic rubber and dispersing it either at the time of its production or after its production by methods similar to that utilized in dispersing natural or reclaimed rubber. the claims the term rubber is used broadly and is to be understood as comprehending synthetic as well as natural rubbers.

This application is a division of our prior copending application, Serial No. 585,334 filed January '7, 1932.

Having thus described our invention, what we claim and desire to protect by Letters Patent is:

1. A fabric comprising knitted yarn with which is associated a deposit containing a minor proportion of casein and a major proportion of rubber, said deposit ranging substantially from 3 to 30% based on the dry weight of the yarn and being substantially indiscernible to the naked eye and imperceptible to the touch, and'said deposit being distributed between the structural elements of the yarn and binding them together into a substantially unitary yarn structure.

2. A fabric comprising knitted yarn with which is associated a deposit containing a minor pro portion of proteinous material and a major proportion or rubber, said deposit ranging substantially from 3 to 30% based on the dry weight of the yarn and being substantially indiscernible to the naked eye and imperceptible to the touch, and said deposit being distributed between the structural elements of the yarn and binding them together into a substantially unitary yarn structure.

MERWYN C. TEAGUE. NEHEMIAH H. BREWSTER.

Accordingly, in