Patented Feb. 14, 1950 2497,519 UNITED STATES PATENT OFFICE 2,497,519 ART OF STABLZNG RAYON TYPE FABRIC Archibald S. Stevenson, Pawtucket, and Leo Beer, Providence, R. I., assignors to Alrose Chemical Company, Cranston, R. ., a corporation of Rhode Island No Drawing. Application December 4, 1946, Serial No. 13,918 15 Claims. (C. 8-125) 2 The textile fabric with the stabilization of the alternative, costly ventilating equipment is which the present invention is concerned, con 'equired, and tains Synthetic fibers of regenerated cellulose, h. Fabrics treated with resins frequently cause Such as viscose or cupra-ammonium rayon or of dermatitis when worn by persons whose skin is cellulose-acetate or other cellulose derivative, the Sensitive to such resins. fabric consisting of any of said fibers, alone or in It is among the objects of the present inven admixture with one or more of the other fibers, tion to produce textile fabrics of the rayon-type with or without components of wool, cotton or which are stabilized to a highly satisfactory de other fiber, natural or synthetic. Fabric of the gree against laundering shrinkage, without there character referred to is designated hereinafter () by incurring excessive loss of yardage and with both in the specification and the claims in the in out the need to this end for incorporating in or terest of brevity as "rayon-type fabric.' on the fibre any foreign substance, or altering As conducive to a clear understanding of the the molecular structure of the fiber or detracting from the weight or the tensile strength or the invention, it is noted that if such rayon-type abrasion resistance of the fibre or fabric or in fabric were subjected to the action of caustic 5 pairing the hand of feel thereof, or objectionably under conditions similar to those of mercerizing detracting from its luster. cotton, i. e., at caustic concentration of 18 to 25 Other objects are the production of stabilized per cent in aqueous solution, at room temperature fabrics by methods readily applied with equip or less for a period of Some minutes, great yard ment now available in modern rayon finishing age loss in processing would be incurred, which 20 plants and with the use of chemicals readily ob in the case of spun rayon may be in the Order of tainable at low cost and by processes simple to 20 per cent or more and may be accompanied control with considerable economy, the saving of also by excessive loss in width. Such merceriza yardage as compared to the loss incurred in tion moreover, despite the yardage loss that it conventional pre-shrinking being sufficient, in entails, would be inefficacious for stabilizing the fact, much more than sufficient to make up for goods since the same would shrink from 0.5 to 2 the cost of applying the process. per cent more on each of several Successive laun Other objects are to produce controlled Swell dering operations. Furthermore, a considerable ing of the rayon-type fiber in the fabric without loss in strength and deterioration in hand and weakening or dissolving said fiber and thereby appearance of the fabric would result. 30 closing the openings in the fabric and imparting Where it is attempted to stabilize rayon fab thereto a fuller and richer appearance and rend rics by the application of unpolymerized or par ering the finally dyed product more attractive tially polymerized resin condensates (e. g. urea in appearance. formaldehyde or melamine-formaldehyde resins) Bearing in mind that the effect of caustic upon objections arise, among which are: rayon-type fabric becomes moderated with in a. Shrink proofing will gradually disappear as crease of concentration of caustic and with rise the resin is washed out through many successive in temperature thereof, the practice of the pres launderings, ent invention involves the treatment of the ray b. The fabric often acquires a stiff feel or on-type fabric with a relatively strong solution 'hand' which even plasticizers or softeners will of caustic as hereinafter more fully set forth, not permanently eliminate, since the latter tend within predetermined limits of temperature, for to Wash out in laundering, a very short period of time measured in seconds c. Fabric So treated may retain chlorine used rather than minutes followed by expression of in certain laundering processes, with subsequent 45 excess caustic solution, and after an adequate deterioration thereof, time interval, neutralization without prior dilu d. Where Such resin-treated fabrics are cured tion of the caustic in the fabric. This is followed with strongly acid catalysts loss in abrasion re by rinsing, scouring and drying in the relaxed sistance results, state, and finally framing to predetermined width. e. The application of these resins after dyeing 50 All of these operations are performed with mini frequently results in change of color and some mum tension along the length of the fabric. times in discoloration, and reduction in light Such treatment results in the stabilization of the fastness, fabric against shrinkage in subsequent launder f. Special equipment not available in some tex ing operations and such stabilization occurs with tile finishing plants is required for the high 55 little or no loss in effective length of the fabric temperature baking of the resin, as compared with the loss of as much as 20 to 25 g. The formaldehyde released in the applica per cent in Such effective length that is incurred tion of resins to the fabric and in the subsequent Where mercerization in the usual sense of the curing operations is objectionable, since the odor term is resorted to. is offensive and involves a health hazard or in 60 The caustic agent used may be potassium hy 2,497,519 3 4 droxide or lithium hydroxide or mixtures thereof ably a 5 to 10 per cent solution of sulphuric acid with Or without sodium hydroxide, but for rea at about 15 to 60 degrees C., but hydrochloric or sons of economy sodium hydroxide is preferred. acetic acid may be used if desired. It is also fea An aqueous solution of the sodium hydroxide or sible to use a hot Saturated solution of sodium bi Other caustic alkali is applied at a concentration carbonate at a temperature of 40 to 80 degrees C., of 30 to 50 per cent at a temperature in the range preferably of about 60 degrees C. of 15 to 80 degrees C. Preferably the concentra Were it attempted to wash out the caustic by tion is between 30 and 40 per cent and the tem a water treatment rather than by neutralization, perature between 20 and 60 degrees C. Where SWelling, parchmentizing and serious loss in ten a concentration of 30 per cent of caustic is used 10 sile strength would be incurred, especially as the the preferred temperature is 40 to 60 degrees C.; caustic concentration passes through the criti where 40 per cent caustic is used, it is preferably cal range of between 6 and 14 per cent NaOH. 20 to 35 degrees C., but may be higher, if acetate After neutralization, rinsing of the fabric is or wool fibers are not present, since the effect of effected, preferably in a sequence of aqueous temperature on viscose rayon is less critical at 5 baths, some hot, some cold, to remove residual this concentration. alkali and salts, followed by withdrawal of excess The caustic solution is applied to the fabric moisture by pressure, centrifugation or vacuum preferably by passing the latter through a bath extraction. of such solution in such manner that no part of The fabric in rope form is then passed through the fabric remains immersed for a period more 20 a beck where it is desized and scoured. There than a few seconds, preferably not more than 2 upon, the goods are dyed and rinsed on the beck, or 3 seconds. The fabric is then squeezed on the or they may be opened out, dried and dyed or padder or quetsch to insure thorough impregna printed in the opened width. tion and removal of excess caustic solution. It is in portant that each of the foregoing steps, Thorough saturation in the very short period of 25 i. e., the caustic treatment, the neutralization, the immersion is assured by adding to the bath .5 rinsing, desizing and scouring, the moisture with to 1.5 per cent, preferably about 1 per cent of drawal, the dyeing following by rinsing and dry a suitable wetting agent which may be a phenolic ing be performed with the fabric under little or Compound, (phenols, Cresols, xylenols or mixtures no lengthwise tension. thereof) with a solvent, desirably ethylene glycol 30 Finally the slack dried fabric is given a mono-butyl ether. For a 40 per cent caustic bath, laundering test which is preferably more severe a Wetting agent of 94 per cent phenol and 6 than ordinarily given to synthetic fabrics. In per cent of Said solvent is especially efficacious. fact the standard wash test for cotton fabrics is The short period of immersion set forth varies preferred, in which the material is laundered at Substantially inversely with the Speed of pene 35 the boil (See Yearbook of the American Associa tration of caustic into the fabric. tion of Textile Chemists and Colorists, 1945, page After squeezing out excess caustic impregnat 219). The laundering shrinkage in warp and fill ing solution on the padder or quetsch, the fabric ing is measured and the required finished width still retains about 60 to 100 per cent of its weight for Zero shrinkage is computed. of caustic Solution. This corresponds to approxi 40 After padding the fabric through water with mately 20 to 50 per cent of actual caustic alkali appropriate Softening, stiffening or other finish (as dry hydroxide) based on the weight of the ing agents, the fabric is dried on the tenter frame fabric. Commercial runs with 25 to 50 per cent to the proper width. Alternatively, it may be of actual NaOH (calculated as dry hydroxide) on relax-dried again, then steamed and framed to the fabric after squeezing have produced adequate the required width. Should there be some small stabilization. residual warp-wise shrinkage in the laundering After the goods have been impregnated with test, mechanical overfeed devices which are avail caustic, and the excess Squeezed out, as set forth, able for tenter frames may be resorted to. By the fibers assume a semi-plastic state and there Way of example, the fabric may be given a further fore the goods should not be put through nips or 50 relaxation treatment on the beck, then slack allowed to wrinkle at this stage. Nor should dried, steamed and framed to proper width, with water drops be permitted to fall on the fabric the required degree of Overfeed. before or after impregnation, Since noticeable de Our process has been Successfully applied to fects would become apparent upon dyeing. For fabric made of yarn of filament or spun staple this reason the fabric must be handled in the open 55 fibers which are of regenerated cellulose (viscose width until it is neutralized, after which stage it or cupra-ammonium), acetate rayon (cellulose may be handled in rope form or open width as acetate), and mixtures of these synthetic fibers desired. with cotton, wool or other fibers, natural or syn After the caustic treatment the fabric is thetic, or with each other. As above noted, "skyed,' that is, run in a span through air from 30 these fabrics are briefly designated as "rayon the caustic padder to the neutralizing bath for type fabrics.' a period such that the total time elapsed from By treating the rayon-type fabric with caustic the entry into the caustic bath to the entry into within the limited range of concentration and the neutralizing bath is from 5 to 50 seconds or within the limited range of temperatures and more, and the skyling time is therefore slightly less 65 for the duration of treatment noted, and by con by the few seconds of immersion. If the fabric ducting said treatment as well as the neutraliza after excess caustic solution has been squeezed tion and the other steps in substantially the out is batched or rolled rather than "skyed' (as absence of tension all as heretofore set forth, the may be required if continuous processing equip present invention avoids the excessive and eco ment is not available), it may be left for a longer 70 nomically wasteful contraction in length and period of time before neutralizing without ad width incurred where the lower concentrations verse effect. and lower temperatures of caustic are used, espe After the "skyling' or batching operation, the cially for the longer periods of time commonly fabric is run directly into the neutralizing bath. resorted to in mercerization practices. In fact, Dilute acids are used for neutralization, prefer- 75 according to the present process, the warp-wise 2,497,519 5 6 contraction is ordinarily 5 per cent or less and actual sodium silicate by dry weight. The sodium in some cases may be entirely absent. Yet the silicate apparently depresses the ionization of the fiber is in no wise impaired, insofar as its tensile caustic and also acts as a protective colloid; strength, its abrasion resistance and its luster possibly it may also protect the fiber during are concerned, nor is there any increase in the neutralization due to deposition of colloidal silica. extensibility or elasticity of the fiber or fabric thereon. as compared to the untreated product. Where the protective agent is applied to the It is frequently preferred to apply the process fabric from aqueous solution and dried thereon directly to grey goods of the rayon type as re prior to the caustic treatment, it may contain ceived from the mill. The goods may be kept at O materials in any of the following categories: their original width by means of expanders be a. Salts of amphioteric metals such as Zinc Sul fore and after entering the padders, resulting in phate, aluminum sulphate, sodium Stannate, and stabilization at a width more nearly equal to sodium silicate (in the case of strongly acid salts the grey width. Also the length of the fabric is such as zinc sulphate and aluminum Sulphate, a much nearer to its original dimensions and much 5 buffer, such as urea, is employed to prevent less loss in yardage is incurred than if the grey deterioration of the fabric While drying). goods were first scoured, a step which is more b. Salts which tend to repress the ionization Over eliminated according to this procedure. of caustic, including sodium chloride, Sodium Sul The treatment of the unpreshrunk grey goods, phate, potassium chloride, potassium sulphate according to the foregoing process, thus accom and borax. plishes the dimensional stabilization above set c. Salts of organic carboxylic or sulfonic acids forth with a total loss in yardage as above set of the aromatic or aliphatic series, Such as forth of only 5 per cent on the unpreshrunk grey sodium benzoate, sodium naphthalene Sulphonate goods as compared with the loss of 10 per cent or resin acid soaps such as Sodium abietate or Or more in the case of filament rayon fabrics or of 25 fatty acid Soaps. as much as 20 per cent in spun rayon fabrics d. High molecular Organic compounds forming finished by ordinary processing methods which protective colloids and not readily attacked under do not result in stabilization. the conditions of treatment described, by sodium While the theory by which we explain the hydroxide, such as methyl cellulose, Salts of car. mechanism or mode of operation of Our process 30 boxymethyl cellulose, gelatin, soy bean protein may not be correct, and we do not wish to be or mixtures of the same. bound thereby, we believe that the caustic treat e. Polyhydric alcohols, carbamides or nix ment under carefully controlled conditions of tures thereof and among which are glycerols, time, temperature and concentration results in glycols, polyglycols and urea. only slight swelling and plasticization of the fiber, 35 A desirable protective agent for this mode of sufficient merely to relax the mechanical strains application consists of a mixture of either pro that had been imposed on the fibers in the course tein or carboxymethyl cellulose admixed with of the twisting of the synthetic yarn and on the either urea or borax. yarn and its component fibers in the Weaving or The concentration of caustic, temperature, the knitting of the fabric therefrom. Since fur 40 time of treatment, charatcer of wetting agent ther handling of the goods is accomplished with and of protective agent used, and the like will of minimum tension to avoid stresses which night course be varied in manner within the Scope of again introduce strains similar to those which those skilled in the art, depending on the fabric had been already removed, the fabric remains to be treated and the result to be accomplished. completely relaxed, and subsequent launderings 45 There are a number of specific examples outlined may be carried out without further contraction below: or shrinkage. The treatment set forth, it is Eacample 1 believed, has in some way permitted molecular or micellar rearrangement to a strain-free condi A caustic impregnating bath of the following tion and this without chemically changing the 50 composition by weight is prepared and allowed fiber or leaving any ingredient therein, or for that to cool before use: matter, effecting any physical change other than Caustic Soda, as NaOH ------30 to 50% as per slight swelling of the fiber. Therefore, aside schedule below from the other advantages pointed out, the prod Sodium silicate, as Na2SiO3 ---- 2.5% uct does not suffer weakening or disintegration, 55 Phenol ------0.93% While satisfactory results are attained by the Ethylene glycol monobutylether.0.06% procedure as above described, improvements in results are attained, by further moderating the Water ------. 66.5 to 46.5% effect of the caustic solution upon the fabric by The temperature and concentration limitations use of a protective agent, that will further limit 60 vary depending on the type of fabric employed the attack of the caustic upon the fabric and will and the effect desired, thus: further limit the swelling action upon the fiber, and improve the hand or feel of the fabric. This Concentra protective agent may be preliminarily applied to NaOHtion of Terra:r the fabric from solution and dried thereon before 65 the caustic treatment, but in the interest of For all 'rayon-types' including acetate Percent oC. and wool------40-50 20-35 economy it is preferred to include such protective 40-45 20-65 agent in the caustic solution and thereby to apply For regenerated cellulose---...------. O 3-35 50-65 concurrently to the fabric the protective agent For partial saponification or cellulose as well as the caustic. 70 acetate------30-50 35-55 In the latter and preferred procedure, as the protective agent, there is admixed with the The fabric (in the grey, scoured, or vat-dyed caustic, sodium silicate solution, desirably 2 to state) under minimum warp tension, is in 10 per cent and preferably 5 per cent by weight, mersed in the open width in the above solution which latter amounts to about 2 per cent of 75 for 1 to 2 seconds, and squeezed on a padder Or 2,497,519 7 quetsch to about 90% liquid pickup based on the weight of dry fabric. After skyling, for 10 to 20 Eacample 4 seconds, the fabric is immersed in a large volume Rayon-type fabrics are treated by a procedure of 5 to 10 per cent sulfuric acid solution, then corresponding to Example 1, except that 40 to washed with water, neutralized in 5 per cent to 5 45 per cent caustic soda is used alone, without 6 per cent hot sodium bicarbonate Solution, and addition of protective agents or penetrants, as rinsed. the swelling agent. The above operations are carried out on a Stabilization as good as that of Example 1 continuous processing unit comprising a padder is obtained. The hand is firmer and slightly followed by a set of skying rollers and a multi harsher, and, hence, this procedure is applicable compartment open-width washer, containing, in only on fabrics where a firmer hand is desired. consecutive compartments: (1) dilute sulfuric It has been used with satisfactory results on acid, (2) water, (3) sodium bicarbonate solution, heavy twill fabrics and on part wool fabrics to (4) hot water, (5) cold water. enhance the Woolly hand. The goods are then scoured in rope form in Eacample 5 the beck, first in boiling Soap solution, then in cold water. The fabric is opened, extracted, Spun rayon or filament rayon fabrics are treat and slack-dried in the loop drier. ed as in Example 3, using 30 per cent caustic soda At this stage, a laundering test is run on at 55 degrees C. Results are similar to Example 3 portion of the goods to determine whether relax except that a firm, crisp hand is obtained. ation is sufficient and to determine the proper Eacample 6 width for zero shrinkage. This method gives satisfactory stabilization on Where the goods have been dyed or printed spun and filament viscose rayons and on cotton before stabilization, they are merely steamed and viscose mixtures and is resorted to when and framed to the predetermined width. If grey continuous equipment is not available. A rayon or scoured goods have been used in the stabiliza type fabric impregnated with caustic soda Solu tion process, they are then dyed, scoured, ex tion as in any of the foregoing examples, in tracted and slack dried again before framing stead of skying is batched onto rolls after leav to the proper width. ing the caustic padder. The above procedure is suitable for stabiliza 30 tion of all types of rayon and mixed fabrics. The roll of cloth is then neutralized on a jig Using 40 to 50 per cent caustic at 20 to 35 de or open-soaper and washed as in Example 1. grees C., cellulose acetate may be treated with: The above examples describe actual commer out saponification, and fabrics containing wool cial applications of our process. Other com or regenerated protein fibers may be treated binations of concentrations, temperatures, and without loss in protein content, and without protective and penetrating agents, within the damage to the wool fibers. limitations herein described, will occur to those Fabrics when treated by the above procedure versed in the art, and may be used to vary the become stabilized to a laundering shrinkage of hand or finish or to adapt the process to the less than 2 per cent. The same fabrics treated 4. equipment available. by the customary rayon finishing methods show While stabilization is accomplished in our shrinkage of 10 per cent to 20 per cent on process without requiring deposition of any for laundering. eign material in or on the fiber, the finisher is free to add any finishing agents he desires to Eacample 2 obtain effects other than stabilization. Thus, he may employ resins for stiffening the fabric Rayon-type fabrics are impregnated with 30 or imparting crease-resistance or he may use per cent caustic potash at 55 degrees C. on a other stiffening or softening agents without de padder, then skyed, neutralized and subsequent parting from the spirit of this invention. ly treated as in Example 1. AS many changes could be made in the above This procedure has been used on heavy process and product and many apparently “tackle-twill fabrics having a filament rayon Widely different embodiments of this invention warp. Whereas, the usual finishing processes could be made without departing from the scope result in a fabric which shrinks 14 per cent in of the claims, it is intended that all matter con five launderings, the fabrics treated by our proc tained in the above description shall be in ess shrink 2 per cent or less. terpreted as illustrative and not in a limiting Eacample 3 SeSe. Having thus described our invention, what we Rayon-type fabrics are precoated by impreg claim as new and desire to secure by Letters nating with an aqueous solution containing a 60 Patent of the United States is: mixture of: 1. The process of treating textile fabric of rayon type by subjecting the fabric while main 2.5% soybean protein tained in the open width to aqueous solution of 0.5% aluminum cellulose glycollate caustic alkali in concentration of 30 to 50 per 2.5% urea 65 cent at a temperature of 20 to 60 degrees C. for 0.5% trisodium phosphate a period of time varying Substantially inversely The fabric is squeezed to a pickup of 90 to 100 with the speed of penetration of caustic into per cent and dried on a tenter-frame at grey the fabric, said period of time being but a few goods width. It is then impregnated with a 30 seconds where the fabric is rapidly Saturated to 50 per cent caustic soda solution on the pad O with said caustic Solution, Squeezing until the der and skyed and neutralized as described in fabric retains 60 to 100 per cent of caustic solu Example 1. tion based on the fabric weight, and, within a Excellent stabilization is obtained by this pro period well under one minute after the start cedure with no loss in strength or deterioration of the caustic impregnation, neutralizing directly in hand or appearance of the fabric, 5 without prior dilution of the caustic in the treated 2,497,619 10 fabric, washing the fabric substantially to free with the speed of saturation of the fabric by the it of the neutralized impregnating agentS, drying caustic, said period of time being but a few sec the fabric and adjusting to predetermined width, onds where the fabric is saturated with caustic all of Said steps being performed under Substan rapidly, squeezing to remove excess alkali, and tially slack condition of the length of the fabric within a period well under one minute after the with resultant stabilization at a length contrac beginning of caustic impregnation effecting neu tion materially less than that incurred in con tralization of the caustic treated fabric, the wash ventional shrinkage treatment. ing of the fabric substantially to free it of the in 2. The process of treating textile fabric of pregnating agents and the drying of the fabric rayon type, which comprises the impregnation O and adjustment to predetermined width, all of of the fabric in a bath containing caustic alkali said steps being performed under substantially of 30 to 50 per cent concentration at a tempera Slack condition of the length of the fabric with ture of 20 to 60 degrees C. for a period of not resultant stabilization at a length contraction more than a few seconds, squeezing Out exceSS materially less than that incurred in conven caustic and passing the caustic impregnated 5 tional shrinkage treatment. fabric through air for a period well under one 9. The process of treating textile fabric of the minute after the start of the caustic impregnation rayon type, which comprises subjecting the fabric and thereupon passing the same through a neu to aqueous caustic alkali in concentration of 30 tralization bath while maintaining it in the open to 50 per cent at a temperature of 20 to 60 de width, washing the fabric substantially to free grees C. in the presence of a protective agent it from the neutralized impregnating agents, Serving to moderate the intensity of the action drying it and adjusting to predetermined width, of the caustic upon the fabric, comprising between all of said steps being performed under Substan and 5 per cent of Sodium silicate admixed in tially slack condition of the length of the fabric solution with the caustic and for a period of time with resultant stabilization at a length contrac 25 varying inversely with the speed of penetration tion materially less than that incurred in conven of caustic to the fabric, said period of time being tional shrinkage treatment. but a few seconds where the fabric is rapidly 3. The process claimed in claim 2, in which Saturated with caustic, Squeezing out excess the caustic alkali is sodium hydroxide of about caustic and within a period well under one minute 30 per cent concentration applied at a tempera 30 after the beginning of caustic treatment effect ture of 40 to 60 degrees C. ing, the direct neutralization of the caustic 4. The process claimed in claim 2, in which treated fabric, the washing of the fabric substan the caustic alkali is sodium hydroxide of about tially to free it of the impregnating agents and 40 per cent concentration applied at a tempera the drying of the fabric, and adjustment to pre ture of 20 to 60 degrees C, and the fabric is 35 determined width, all of said steps being per squeezed to ensure thorough impregnation and formed under substantially slack condition of the to remove excess caustic Solution. length of the fabric with resultant stabilization 5. The process recited in claim 1, in which after at a length contraction materially less than that washing, color is applied to the fabric under incurred conventional shrinkage treatment. minimum tension thereon, and the fabric is O 10. The process recited in claim 9, said solution then dried without tension and adjusted to pre containing about 2 per cent by weight of sodium determined width, silicate admixed in solution with the caustic. 6. The process of treating textile fabric of 11. The process of Stabilizing textile fabrics rayon type, which comprises the impregnation of of the rayon type in the unshrunk grey goods the fabric in a bath containing caustic alkali of 5 stage, which comprises Saturating the goods with about 40 per cent concentration at a temperature aqueous Solution of caustic in concentration of of 20 to 60 degrees C. for a period of not more 30 to 50 per cent at a temperature of 20 to 60 than a few seconds, Squeezing excess caustic degrees C. for a period of not more than a few from the fabric, passing it through the air for a Seconds, Squeezing out the excess caustic solu period well under one minute after the com tion and thereupon within a period well under mencement of the impregnation and thereupon One minute after the start of the caustic in impregnating the fabric in a neutralizing Solution, pregnation, treating the fabric in neutralizing washing the fabric substantially to free it of Solution, and then washing and scouring the the neutralized impregnating agents, drying it fabric for removal of Substantially all of the and framing to predetermined width, all of said 5 5 neutralized treating agents, and adjusting to pre steps being performed under slack condition of determined width, all of said processes being con the length of the fabric with resultant stabiliza ducted on the Substantially slack condition of tion at a length contraction materially less than length of the fabric with resultant stabilization that incurred in conventional shrinkage treat and, length contraction materially less than that ment. O incurred in conventional preshrinking. 7. The process recited in claim 6 in which the 12. The process of treating textile fabric of residual alkali and salts are removed in a Suc rayon type by impregnating the fabric in aqueous cession of water washes and in which the Wash ing is conducted upon the fabric in rope form solution of caustic alkali in concentration of under slack conditions and the drying and Sub 30 to 50 per cent at a temperature of 20 to 60 de sequent application of coloring are effected under grees C. for not more than a few seconds, Squeez relatively slack condition. ing out the excess caustic Solution, batching 8. The process of treating textile fabric of the fabric and thereafter in regular course of rayon type, which comprises subjecting the fabric handling, subjecting the fabric to neutraliza to aqueous caustic alkali in concentration of 30 tion, washing substantially to free it of the neu to 50 per cent at a temperature of 20 to 60 de tralized impregnating agents, drying the fabric grees C. performed in the presence of protective and framing to predetermined width, all of Said agent serving to moderate the intensity of the steps being performed under Substantially slack action of the caustic upon the fabric and for condition of the length of the fabric with re a period of time varying substantially inversely s sultant stabilization at a length contraction ma 2,497,519 11 2 terially less than that incurred in conventional termined width, all of said steps being performed shrinkage treatment. under Substantially slack condition of the length 13. The process recited in claim 1 in which of fabric with resultant stabilization at a length the speed of penetration of the caustic Solution contraction materially less than that incurred into the fabric is expedited by the addition to the in conventional shrinkage treatment, bath of a wetting agent in proportion of about .5 ARCHIBALDS, STEVENSON. to 1.5 per cent by weight. LEO BEER, 14. The process recited in claim 1 in which the speed of penetration of the caustic Solution REFERENCES CTED into the fabric is expedited by the addition to O The following references are of record in the the bath of a wetting agent in proportion of about 5 to 1.5 per cent by weight, said wetting agent file of this patent: being a phenolic compound with a solvent of UNITED STATES PATENTS ethylene glycol monobutyl ether. Number Nanne Date 15. The process of treating textile fabric of 15 1851,914 Lier ------Mar. 29, 1932 the rayon type, which comprises immersing the 1989,098 Lilienfeld ------Jan. 29, 1935 fabric in a solution of an aqueous caustic alkali 1989,100 Lilienfeld ------Jan. 29, 1935 in concentration of 30 to 50 per cent containing 1989,101 Lilienfeld ------Jan. 29, 1935 also a protective agent comprising between 1 and 5 2,112,499 Lilienfeld ------Mar. 29, 1938 per cent of sodium silicate and a wetting agent 20 in percentage of .5 to 1.5 per cent at a tempera FOREIGN PATENTS ture of 20 to 60 degrees C. for a period of time Number Country Date not exceeding 3 seconds, squeezing out excess 437,485 Great Britain ------Oct. 30, 1935 caustic and thereupon within a period well under 462,899 Great Britain ------Mar. 17, 1937 one minute after the start of caustic impregna 25 501,768 Great Britain ------Mar. 6, 1939 tion directly neutralizing the caustic treated 546,673 Great Britain ------July 24, 1942 fabric, washing it substantially to free it of the 560,378 Great Britain ------Apr. 3, 1944 impregnant, drying it, and adjusting to prede