US2469249A - Process of scouring cellulosic textiles using steam - Google Patents

Description

Patented May 3, 1949 UNITED STATES OFFICE PROCESS OF SCOURING CELLULOSIC TEXTILES USING STEAM tion of Virginia No Drawing. Application November 2'7, 1945, Serial No. 631,222

3 Claims.

The present invention relates to the finishing of cellulosic textiles, for instance unfinished cotton textiles and the like, and more particularly to finishing operations wherein the textile is subjected to a steaming while impregnated with a treating solution and is thereafter washed.

The invention is of particular utility in the treatment of unfinished, predominantly cellulosic textiles, such as greige cloth, for the removal of natural color bodies, adhering solid impurities, such as motes, natural waxes and pectins and sizings, principally of starchy material, added to the textile during prior processing, and to improve the color or absorbency of the textile.

An especially useful application of the process is in the scouring of such textile materials by subjecting the textile to a steaming while impregnated with a caustic soda solution.

It has heretofore been proposed to scour textile materials by subjecting them to a steaming while impregnated with a caustic soda solution for the purpose of removing impurities and improving absorbency. However, such operations have not met with commercial favor for the reason that uniform absorbency has not been readily obtainable by this method of scouring. In order to obtain uniform absorbency it has been necessary to repeat the steaming operation a number of times, and even so, satisfactory results have not been consistently obtained.

In such operations as previously proposed, the textile after passing from the steamer has been piled into boxes or the like and carried to the washer, or else has otherwise been subjected to substantial cooling in passing from the steamer to the washing operation. The Washing operation has usually been carried out in cold water after the textile has cooled to substantially room temperature.

We have discovered that surprisingly improved results are obtained in such operations if the temperature of the textile be not permitted to fall below about 140 F. during the period of its passage from the steaming operation to the Washing operation. Normally the textile will leave the steaming operation at a temperature of about 200-212 F., and we have found it particularly desirable to maintain the temperature of the textile at not lessthan about 160 to 180 F. during the interval between the steaming and washing operations. It is further desirable that the washing. operation be carried out with hot water.

While we do not propose to be bound to any theory as to the reason for the improved results obtained in accordance with our present invention, it is our present belief that in such operations as previously carried out, the pectins and like impurities which are solubilized by the caustic steaming become resolidified in the textile prior to washing so that they are not completely or uniformly removed by thewashing operation and that the presence of such resolidified impurities has been responsible, in part at least, for the lack of uniform absorbency of the textile. By maintaining the textile at a temperature above that at which any substantial resolidification of these impurities is effected, the materials solubilized by the steaming treatment are readily and uniformly washed from the fabric, particularly if water at an elevated temperature be used in the Washing operation.

In scouring the textile, for instance, in accordance with our present invention, the textile is impregnated as by padding with the caustic solution, preferably hot, excess caustic solution is then drained or squeezed from the textile and the textile wet with the caustic solution is subjected to steaming. For this purpose, steam at atmospheric pressure is generally used and the textile will pass from the steaming chamber at a temperature of about 205-212 F. and from thence is passed to the washing operation without permitting its temperature to fall below about F., preferably not below ISO-180 F.

Various means may be provided for maintaining the textile at the desired temperature while passing from the steamer to the washer. For instance, the washer may be placed close to the exit end of the steamer and connected to the steamer by a conduit or other meansfor preventing excessive heat loss by the textile in passin from the steamer to the washer. Where the washer cannot conveniently be placed close to the exit of the steamer, it may be desirable to mildly heat such conduit to prevent excessive heat loss from the textile to the surrounding atmosphere. In place of such a conduit, other suitable means for maintaining the textile at the desired temperature may be employed.

By maintaining the textile at the indicated temperature during its passage from the steaming operation to the washing operation, and by using hot wash water, good uniform absorbency has been obtained by a single steaming of the textile, so that an even dyeing of the textile is obtainable without repeating the scouring operation, particularly where the textile is to be dyed a dark color. Where the textile is to be dyed a pastel shade it may be desirable to subject the treated textile to a bleachin operation prior to dyeing.

The invention has also been found applicable to bleaching operations wherein the textile impregnated with the bleaching solution is subjected to a steaming and subsequently washed. For instance, particularly advantageous results have been obtained by utilizing the present invention in conjunction with a bleaching operation whereby the textile impregnated with an aqueous solution of a chlorite is steamed. In such operations, improved results have been obtained by maintaining the textile at a temperature within the range previously indicated, while passing from the steaming to the washing operation.

In normal operation in a finishing mill, it has been found that even at the high velocity at which the textiles frequently pass from one operation to another, while exposed to the atmosphere, the normal temperature drop due to atmospheric cooling and evaporation is very considerable, even over distances of travel of only a few feet. Even when the textile is passed through an enclosed conduit, it has been found desirable to heat said conduit, as by means of steam, to a temperature of not less than about 180 R, if the length of the conduit is greater than about feet, assuming a velocity of travel of about 100 yards per minute.

Where the textile is carried from the steamer to the washing operation in boxes, it may be necessary to protect the textile from heat loss in passing from the steamer to the boxes and from the boxes to the washer. Also closed boxes may be used.

Though exceptionally satisfactory results are obtained in accordance with our invention when hot water is used in the washing operation, greatly improved absorbency and uniformity of absorbency are obtained, even though cold water be usedin the subsequent washing operation.

It will be understood that the utility of our present invention is not restricted to any particular method of steaming. It is, for instance, applicable to operations wherein the steaming is carried out in rope form or is carried out at full width, and the textile may be impregnated with the scouring solution, for instance by immersion, padding, spraying or any other satisfactory procedure which insures reasonably thorough wetting of the textile.

Neither is the utility of the present invention restricted to an operation wherein some particu lar concentration of the reagent is employed. The concentration of the caustic solution, for instance, may be varied over a considerable range in accordance with the recognized practice.

In bleaching operations, for instance, where sodium chlorite is used as the bleaching agent, the impregnating solution may be either acid or alkaline. In scouring solutions such as caustic solutions, it has been found particularly desirable to include a detergent in the impregnating solution, for instance a synthetic organic detergent such as sulfated or sulfonated organic compounds active in alkaline solution.

The invention, as previously noted, is applicable to finishing operations wherein the textile is steamed while impregnated with an aqueous solution of sodium chlorite, either acid or alkaline, depending upon the nature of the impurities to be removed, as more particularly described in our co-pending application Serial No. 357,280, filed September 18, 1940, now abandoned. A further particularly desirable application of our present invention is in the finishing of textiles containall ing predyed threads, as more fully described in the co-pending application of the present applicants and another, Serial No. 358,664, filed September 27, 1940, in accordance with which the textile is steamed while impregnated with an aqueous alkaline solution containing a minor proportion of sodium silicate, the sodium silicate serving to prevent the running of the dye of the predyed threads normally encountered in the treatment of such textiles with strong alkaline solutions. In each of these processes the textile is normally subjected to a washing operation prior to further treatment, and particularly desirable results are obtained in accordance with our present invention by preventing the cooling of the textile to a temperature :below about F. between the steaming and the washing operation. In many instances subsequent treatment of the textile heretofore found essential to the obtaining of the desired results may be completely avoided, or at least such subsequent treatment materially reduced in extent or severity.

The invention will be further illustrated by the following specific examples of its application. It will be understood, however, that the invention is applicable generally to textile treating operations in which the textile is subjected to a steaming while impregnated with a treating solution and is thereafter washed.

Example I A cotton greige broadcloth, following the customary singeing, acid treating and drying, is impregnated with an alkaline aqueous solution made up, for instance, of gallons of water, 60 pounds of a 25% solution of caustic soda, 6.5 pounds of sodium chlorite, and 10 pounds of a synthetic detergent consisting essentially of sodium ocenol sulfate. This solution is preferably applied hot to the textile, say at a temperature of about 125 1".

After draining or squeezing the excess solution therefrom, the textile is passed into a steam chamber and subjected to contact with steam at atmospheric pressure for about one-half hour.

The cloth leaving the steam chamber at a temperature of about 200-212" F. is then passed through a conduit heated to about 180 F. directly to the washing operation wherein the textile is subjected to the customary washing, preferably with hot water.

The absorbency of the textile thus treated has consistently been found to be superior and more uniform than a textile similarly treated except that it was permitted to cool to a temperature below 140 F. in the interim between the steaming and washing operations.

Example II A cotton greige cloth containing predyed threads which under ordinary conditions would run when subjected to steaming while impregnated with strong alkalis, is impregnated with an aqueous solution having a pH of about 11-115 and containing about 1 of sodium silicate, about 3% of trisodium phosphate, and about /2% of a synthetic organic detergent of the type noted in Example I. After removing the excess solution, the impregnated textile is subjected to a steaming for a period of about one-half hour at atmospheric pressure, and thereafter, while maintaining the temperature of the textile at about C., the textile is passed directly to a conventional washing operation wherein it is washed preferably with hot water.

Textiles thus treated have consistently been found to have a, more uniform absorbency, and to be superior with respect to size and mote removal, as compared with the same material similarly treated except that the temperature was permitted to drop to below 140 F. during the interval between the steaming and washing op erations.

In operations such as just described, considerable latitude is permissible with respect to the concentrations and proportions of the respective reagents without loss of the benefits derived from the present invention. For instance, in the type of operation described in Example II, the sodium silicate constituent may vary from about /z% up to about 840%, or even somewhat higher. The pH of the impregnating solution is pref erably within the range of about 9.5 to about 12, and may be adjusted by the addition of an alkaline material such as trisodium phosphate, scdium carbonate or tetrasodium pyrophosphate. However, in the presence of the sodium silicate, stronger alkalis, such as sodium hydroxide, may be used without causing running of the predyed threads. Trisodium phosphate, for instance, in proportions within the range of about up to about 5% may with advantage be incorporated in the impregnating solution. The proportions of the other reagents may likewise be varied over a considerable range so as to effect the desired pH of the solution. Impregnating solutions having pH values even somewhat in excess of 12 may be used.

In straight caustic steaming, the process is carried on as just described, except that the impregnating solution is an aqueous solution of caustic soda which may with advantage, though not necessarily, contain a detergent. In such solutions the concentration of the caustic soda may correspond to those used in ordinary kier 1 boiling and may vary within the range, say, from about 0.5% to about 6.0% by weight.

We claim:

1. In the process of scouring cellulosic textile materials wherein the textile, while impregnated with an aqueous scouring liquor, is subjected to the action of steam in a steaming zone and is thereafter removed from the steaming zone and transferred to a physically remote washing zone, the improvement which comprises maintaining the textile at a temperature not lower than about F. during the interval between the steaming operation and the washing operation.

2. In the process of scouring cellulosic textile materials wherein the textile, while impregnated with an aqueous caustic soda scouring liquor, is subjected to the action of steam in a steaming zone and is thereafter removed from the steaming zone and transferred to a physically remote washing zone, the improvement which comprises maintaining the textile at a temperature not below about 40 F. during the interval between the steaming operation and the washing operation.

3. In the process of scouring cellulosic textile materials wherein the textile, while impregnated with an aqueous caustic soda scouring liquor, is subjected to the action of steam in a steaming zone and is thereafter removed from the steaming zone and transferred to a physically remote washing zone, the improvement which comprises maintaining the textile at a temperature not below -180 F. during the interval between the steaming operation and the washing operation.

GEORGE P. VINCENT. ARCHIE LOUIS DUBEAU.

REFERENCES CITED The following references are of record in the file of this,patent:

UNITED STATES PATENTS Number OTHER REFERENCES American Dyestuff Reporter for December 4, 1944, pages 536, 537, 538.