US2751278A - Process for the chemical modification of cotton sliver with sodium hydroxide solution - Google Patents

Description

PROCESS FOR THE CHEMICAL MODIFICATION OF COTTON SLIVER WITH SGDIUM HYDROX- IDE SULUTION Wilson A. Reeves, James R. Corley, and John D. Guthrie, New Orleans, La, assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Application July 24, 1951, Serial No. 238,366

1 Claim. (Cl. 8-125) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention herein described may be used by or for the Government of the United States of America for governmental purposes throughout the world without the payment to us of any royalty thereon.

This invention relates to the production of chemically modified cotton fiber and to its conversion into yarns. More particularly, it provides a method of producing cotton fiber modified by chemical treatments involving the use of sodium hydroxide solutions of mercerizing strength without the necessary employment of complex or specialized apparatus to accomplish the modification or to process the fiber.

The advantages attained by chemically modifying cotton have long been recognized. Similarly, the advantages of having the modified cotton in the form of fibers that can be blended with other fibers have long been recognized. However, comparatively little chemically modified fiber has theretofore been produced. Its production by the methods heretofore known required the employment of costly specialized equipment, such as centrifuges or complex conveyor belts for use during the treatment, or required a twisting together of the fibers which twisting inevitably resulted in a portion of fibers being shielded from the action of the chemical reagents and thus in the production of a mixture of fibers treated to varying degrees.

The suitable ranges of concentration for sodium hydroxide solutions to mercerize cotton fibers or to accomplish the numerous desirable chemical modifications which involve the employment of sodium hydroxide solutions, such as aminization, carboxyalkylation, and sulfoethylation, have been well established. Since a failure to thoroughly wet all of the fibers with the sodium hydroxide containing solutions is known to result in the production of undesirable mixtures of fiber treated to varying degrees, and since all of the unreacted solution can readily be recovered and reused, the prior methods for accomplishing a chemical modification of cotton consistently employed large excesses of the sodium hydroxide solutions. A cotton sliver immersed in a large excess of such a solution will not support the weight of the combined and adsorbed liquid and will break if an attempt is made to draw it from the solution as a continuous strand.

We have made the discovery that if the amount of the sodium hydroxide solution which comes into contact with cotton fibers in the form of slivers is properly controlled all of the fibers are uniformly chemically modified, and the sliver can be processed as a continuous strand using the ordinary textile processing apparatus. We have demonstrated that this result is obtained whether the sodium hydroxide is pure (i. e., a mercerizing solution) or contains any of the commonly employed cotton modifying reagents, and whether the sliver is wetted with the solution batch-wise in cans or continuously in padders, quetchs, or other ordinary textile processing apparatus.

Furthermore, contrary to the commonly accepted belief that sliver treated with mercerization strength sodium States Fatent G F 2,751,278 Patented June 19, 1956 hydroxide or other chemical modifying agents causing swelling is in a matted condition unsuited to drawing or opening, we have found that the sliver processed according to our method is sufiiciently free of mat to be put through a drawing frame and converted into yarn and fabric.

In general, the present invention involves chemically modifying cotton by wetting it in the form of a sliver with a chemical modifying solution containing sodium hydroxide in mercerizing strength by using an amount of said solution suflicient to wet all of the fibers, but insufiicient to allow the sliver to entrain enough liquid to cause it to break as it is withdrawn from the container in which it was wetted in the form of a continuous strand. This amount of sodium hydroxide solution with which the sliver should be contacted as by immersion, and which will be adsorbed and entrained by the sliver, is substantially ten times the Weight of the sliver. However, the exact amount may vary with the composition of the sodium hydroxide solution, the character of the cotton fibers, the temperature of the treatment, etc., and for each particular case the amount to be used for particular mate-- rials and conditions can be readily determined by a simple test. For example, where the sliver is to be wetted in cans, the alkali solution is poured in and allowed to disperse through the sliver; too much solution will cause the fiber to part as it is withdrawn, or will leave a substantial portion of liquid in the can. Where the sliver is to be wetted continuously (in a padder, for instance) the sliver is started dry through the machine at the speed and temperature desired and the solution is introduced until all the emerging fibers are wetted. If the amount of solution in the trough is enough to result in a contacting of the sliver at the speed at which it is moving, with more than the indicated amount, the sliver will part. It is obvious that the amount of solution with which the sliver is contacted in such an apparatus can also be adjusted by varying the speed at which the sliver moves through the apparatus.

The sliver wetted with the amount of sodium hydroxide required by the process of this invention can be immediately washed by the use of the ordinary processing apparatus; or can be put through a curing, heating, or drying process where it is desired to promote or prolong the reaction of the cotton with particular components of the sodium hydroxide solution. For example, the curing can be accomplished by passing the sliver over rotating heated cans, through ovens, or through curing chambers. The washing can be accomplished by putting the cured sliver through water and then through squeeze rolls. The washed sliver can be dried by putting it over heated steam cans, putting it through a drying chamber, or by merely allowing it to dry in air at room temperature.

The amount of the sodium hydroxide solution merely entrained by sliver treated in accordance with the process of the invention can be recovered by the use of squeeze rolls as they are commonly used in the art. The chemical treatment in accordance with the invention can suitably be accomplished at any of the temperature ranges ordinarily employed for such treatments. Similarly, the treatments can be preceded by, or accompanied by, treatments with any of the commonly employed wetting or dispersing agents, e. g., phenolic compounds, such as cessylic acid, with or without solvents such as hexanol to increase the wetting power, sulfonated acids, sulfuric esters of aliphatic alcohols, etc.

A sliver after being chemically treated in accordance with the process of this invention can readily be dried and directly converted into yarn or it can be opened by putting it through any of the drawing frames commonly employed in processing textiles. After one or more drawings the sliver can be spun into yarn by any of the conventional methods. Alternatively it can be put through any of the commonly used openers and converted into picker lap or again drawn into sliver.

A particularly preferred embodyment of our invention constitutes the conversion of slivers treated in accordance With the invention into picker lap. The invention so applied provides a particularly economical process of producing uniformly chemically modified cotton fiber suitable for any of the manifold uses for such fiber. The production of chemically modified fiber in this manner requires no more than the conventional textile processing equipment.

In order to illustrate certain phases and applications of the present invention in detail, the following specific examples are presented. However, as it is obvious that many modifications in materials, apparatus and technique are Within its scope, the invention is not to be construed as being limited to the particular substances or steps recited therein.

EXAMPLE I M ercerz'zation A roll of 3 pounds of cotton sliver in the form in which it came from the card Was placed in a can and wetted with 32 pounds of a solution composed of 25 parts of sodium hydroxide, 74.6 parts of water and 0.4 part of a wetting agent of the cresylic acid type. After the sliver was completely and uniformly wetted with the solution it was put through squeeze rolls. It was then washed by being put, several times, through water and through squeeze rolls. it was dried by being put over heated steam cans or, in some cases, by being put through a drying oven.

Some of the dried sliver was put through a drawing frame, processed through an opener, carded, drawn and converted into yarn. Some of the dried sliver was also drawn and converted into yarn without putting through the opener. The yarn had the characteristics of mercerized cotton yarn.

EXAMPLE II Aminization A roll of 8 pounds of cotton sliver in the form in which it came from the card was placed in cans and wetted with 80 pounds of a solution composed of 25 parts of sodium hydroxide, 64.6 parts of water, 10 parts of Z-aminoethyl sulfuric acid and 0.4 part of a Wetting agent. After the sliver was completely and uniformly wetted with the solution it was put through squeeze rolls and then heated in a drying oven at 110 C. for 1 hour to cause the 2- arninoethyl sulfuric acid to react with the cellulose of the cotton and introduce amino groups. The cured sliver was then washed by putting it through water and passing it through squeeze rolls. Some of it was dried by hanging EXAMPLE III Continuous chemical treatment Cotton sliver was processed in a manner similiar to that described in Example II, except that the sliver was started dry through a padder and the aminizing solution was poured into the trough while the sliver was running through the padder. The trough was filled with an amount of solution which caused each fiber to emerge wet.

EXAMPLE IV Carboxyalkylation Cotton sliver was processed in a manner similiar to that described in Example II, except that a solution composed of 69.6 parts water, 25 parts sodium hydroxide and 5 parts chloroacetic acid and 0.4 part of Wetting agent was used. The resulting material had the properties of partially carboxymethylated cotton.

EXAMPLE V Sulfoethylatiolz Cotton sliver was processed in a manner similiar to that described in Example II, except that a solution com posed of 69.6 parts of water, 25 parts of sodium hydroxide, 5 parts of Z-chloroethyl sulfonic acid and 0.4 part of a wetting agent were used. The resulting material had the properties of partially sulfoethylated cotton and was.

useful as a cation-exchange material.

Having thus described our invention, we claim:

A process of producing chemically modified cotton comprising immersing cotton in the form of a sliver in an aqueous solution containing a mercerizing amount of sodium hydroxide until the Weight of solution adsorbed and entrained by the cotton is substantially 10 times the weight of the cotton, and removing the so-modified cotton in the form of sliver from the solution.

References Cited in the file of this patent UNITED STATES PATENTS 1,905,268 Cotchett Apr. 25, 1933 2,002,106 Bodmer et al May 21, 1935 2,528,793 Secrist Nov. 7,- 1950 FOREIGN PATENTS 524,805 Great Britain Aug. 15, 1940