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.