US2472238A

US2472238A - Recovery of wool from wool-acetate fabrics

Info

Publication number: US2472238A
Application number: US525954A
Authority: US
Inventors: George C Ward; Roger U Genazzani
Original assignee: Celanese Corp
Current assignee: Celanese Corp
Priority date: 1944-03-10
Filing date: 1944-03-10
Publication date: 1949-06-07
Anticipated expiration: 1966-06-07
Also published as: GB588700A

Description

Patented June 7, 1949 UNITED STATES RECOVERY OF WOOL FROM WOOL-ACETATE FABRICS George C. Ward,

Genazzani, New York,

Cumberland, Md., and Roger U.

N. Y., assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application March 10, 1944, Serial No. 525,954

6 Claims.

This invention relates to the treatment of mixed textile materials and relates more particularly to the treatment of textile materials comprising a mixture of wool and organic ester of cellulose fibers, whereby the wool fibers may be recovered in an economical and convenient manner.

An object of this invention is the provision of a novel process for the recovery of wool fibers from textile materials comprising wool and organic ester of cellulose fibers.

Another object of this invention is the treatment of waste materials comprising wool and organic ester of cellulose fibers whereby the organic ester of cellulose fibers may be removed and clean, strong wool fibers of unimpaired textile properties may be recovered.

Other objects of this invention will appear hereinafter from the following detailed description.

In textile operation-s involving the use of wool and cellulose acetate or other organic ester of cellulose yarns, there isproduced a certain proportion of waste consisting of a mixture of wool and cellulose acetate or other organic ester of cellulose fibers. Such mixtures may be dyed in a solid shade, but the dyed mixture is of value only where there is a need for a textile material containing the particular fibers in the precise proportions present in the waste. Where, for example, a mixture of wool and cellulose acetate fibers is available and only the relatively valuable wool in the mixture is desired the only practical solution to the recovery of the wool is to remove the non-woolen materials. The recovery of the wool must, of course, be effected in such a manner that the wool fibers are left undamaged. Such a process, adapted to commercial operation, has long been sought.

We have now discovered that mixtures of textile materials comprising wool and cellulose acetate fibers may be treated in a novel manner and pure Wool fibers of unimpaired textile properties may be recovered therefrom. In accordance with our novel process, this valuable result may be achieved if a mixture of waste fibers comprising wool and cellulose acetate fibers, from which the color is preferably substantially stripped, is subjected to the action of an alkaline saponification bath of a particular composition and concentration, whereby the cellulose acetate fibers are saponified to yield regenerated cellulose fibers and, following saponification, the resulting mixtur is subjected to carbonization whereby the cellulosic fibers are removed. The carbonization treatment eliminates the cellulosic fibers present and the product recovered comprises clean wool fibers free of all non-woolen materials and possessing eminently satisfactory textile properties.

The saponification of the cellulose acetate fibers in the mixture without injury to the wool fibers present requires careful control of both the temperature and composition of the saponifying bath, since wool fibers, as is well known, are quite sensitive to the action of alkaline materials. We have found, however, that the disadvantageous effects of alkaline media on wool may be overcome by incorporating in the saponifying bath an inorganic salt which acts to inhibit the action of the alkali on the wool. Asexamples of suitable salts, there may be mentioned sodium sulfate, sodium chloride or sodium acetate. Such inhibitors may comprise from 5 to 25% by weight of the saponifying bath. As suitable saponifying agents, we may employ inorganic agents such as, for example, sodium hydroxide, potassium hydroxide, sodium silicate, ammonium hydroxide and sodium carbonate, or organic agents such as, for example, methyl amine, ethylene diamine, triethanolamine, or other organic bases. The saponifying baths employed are preferably aqueous solutions containing the saponifying agent in a concentration of 0.1 to

1%. Satisfactory results are achieved with the saponifying bath at temperatures of 10 to 50 C. and the saponification may be continued for 20 minutes to 24 hours. The most advantageous results are obtained employing an aqueous saponifying bath comprising about 0.2 to 0.6% by weight of sodium hydroxide containing 15 to 20% of sodium sulfate and saponifying for 30 minutes to 16 hours at 20 to 40 C. The more dilute the solution employed the more extended may be the period of saponification.

The carbonization may be effected by treating the mixture of wool and cellulosic fibers with a solution of a suitable carbonizing agent at a temperature of about 15 to 40 0., say room temperature, removing the fibers from the solution, drying, and then baking for 5 to 30 minutes at a temperature of to C. After baking, the dry fibers are shaken in a duster, neutralized, if desired, rinsed well and dried. The wool fibers obtained after carbonization may be utilized in any application Where wool fibers are normally employed and retain all of their desirable textile characteristics.

As suitable carbonizing agents we may, for example, employ'aqueous solutions of sulfuric acid or aluminum chloride, which agents may be present in solution in concentrations of from 4 to 8%. Optimum results are achieved employing the carbonizing agent in concentrations of 2 to 7%. Gaseous hydrogen chloride may also be employed as the carbonizing agent in place of aluminum chloride which, of course, yields hydrogen chloride when heated during the baking operation.

Although we have indicated in the foregoing detailed description that the recovered wool fibers are free of cellulose ester materials after being processed in accordance with our invention, it is to be understood, however, that in large scale commercial operations some incompletely saponified cellulose ester fibers may remain after processing, especially where some of the cellulose ester fibers originally present in the mixture are of relatively high denier. The saponification need not be efi'ected, usually, under such conditions as to make complete saponification of such heavy denier fibers absolutely certain. The presence of such incompletely saponified fibers in an amount of 1 to 2% by weight, or even more, in some instances, may be completely disregarded from a practical point of view since such amount cannot be detected in the wool fibers by visual examination even when samples of the recovered wool fibers are dyed with dyestuffs having an aifinity for wool only and the wool is dyed in deep shades.

While our invention has been described more particularly in connection with the treatment of waste materials comprising wool and cellulose acetate materials to recover the wool fibers therefrom, mixtures of wool, cellulose acetate and cellulosic fibers are commonly encountered in commercial operations and the examples will be directed to the recovery of wool fibers from such mixtures.

In order further to illustrate our invention but without being limited thereto the following examples are given.

Example] 200 parts by weight of a mixture of colored waste staple fibers comprising 60% by weight of wool fibers, 6% by weight of cellulose acetate fibers, 24% by weight of cellulose fibers and 10% of oil are stripped of theircolor by treating for 20 minutes in a 1% solution of sodium hydrosulphite at 50 C. and are then rinsed well in warm water. This treatment does not remove the color entirely but lightens the over-all color effect to a substantial degree. The stripped mixture of waste fibers is then immersed in a saponifying bath comprising 0.6% by weight of sodium hydroxide and 20%. of sodium sulfate at a temperature of 40 C. for 30 minutes. The fibers are removed, rinsed well and then carbonized by immersion in a 6% aqueous solution of sulfuric acid at 28 C. for 10 minutes. The fibers are removed, from the sulfuric acid solution, dried and then baked at 100 C. for 10 minutes. The dried fibers are rinsed again after baking, and after drying, the fibers remaining after this treatment are found to be substantially free of all cellulose acetate and cellulosic fibers and to comprise pure wool fibers. The wool obtained is of unimpaired textile properties.

Example II In lieu of employing asaponification process as given above, the stripped mixture of waste fibers may be saponified in a solution comprising 0.2% of sodium hydroxide containing by weight of sodium sulfate at 20 C. for 16 hours. After being rinsed well, the treated fibers may be carbonized by treatment with a 7% aqueous solution of aluminum chloride at 28 C. for 10 minutes, dried, and baked at C. for 10 minutes. The dry fibers are dusted, rinsed in a 1% solution of hydrochloric acid, which is followed by a second rinse in warm water. After drying, the fibers are found to be substantially free of any cellulose acetate and cellulosic fibers and may be spun into woolen or worsted yarns whose textile properties are entirely satisfactory.

It is to be understood, of course, that our novel process may be applied to any textile material, such as, for example, a fabric made of or containing a mixture of textile fibers comprising wool and cellulose acetate or wool, cellulose acetate and cellulosic fibers, and after treatment a pure Woolen fabric may be obtained. In this manner, many novel and decorative effects may be obtained by weaving a fabric of wool and cellulose acetate yarns or fibers and then removing all of the non-woolen fibers.

While the foregoing description is directed primarily to the treatment of mixtures of wool with cellulose acetate, which mixture may contain cellulosic fibers, other organic esters of cellulose such as, for example, cellulose propionate, cellulose butyrate and cellulose acetate-butyrate, may be removed in like manner from textile materials in which they are present together With wool.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

Process for the recovery of wool from mixed textile materials containing wool and cellulose acetate fibers, which comprises immersing said fiber mixture in an aqueous solution containing from 0.1 to 1% of sodium hydroxide and 5 to 25% of sodium sulfate so as to cause the saponification of the cellulose acetate fibers to yield regenerated cellulose, and carbonizing the cellulose fibers from the fiber mixture, whereby wool fibers substantially free of other textile materials are obtained.

2. Process for the recovery of wool fibers from mixed textile materials containing wool and cellulose acetate fibers, which comprises im mersing said fiber mixture in an aqueous solution containing from 0.1 to 1% of sodium hydroxide and 5 to 25% of sodium sulfate so as to cause the saponification of the cellulose acetate fibers to yield regenerated cellulose by maintaining the fiber mixture in said aqueous solution for from 20 minutes to 24 hours at 10 to 50 C., and carbonizing the cellulose fibers from the fiber mixture, whereby wool fibers substantially free of other textile materials are obtained.

3. Process for the recovery of wool fibers from mixed textile fibers containing wool and cellulose acetate fibers, which comprises immersing said fiber mixture in an aqueous solution containing 0.6% of sodium hydroxide and 20% of sodium sulfate for 30 minutes at 40 C. to cause the saponification of the cellulose acetate fibers and to yield regenerated cellulose, and then carbonizing the cellulose fibers from the fiber mixture, whereby wool fibers substantially free of other textile materials are obtained.

4. Process for the recovery of Wool fibers from mixed textile fiberscontaining wool and cellulose acetate fibers, which comprises immersing said fiber mixture in an aqueous solution containing 0.2% of sodium hydroxide and of sodium sulfate for 16 hours at 20 C. to cause the saponification of the cellulose acetate fibers and to yield regenerated cellulose, and then carbonizing the cellulose fibers from the fiber mixture, whereby wool fibers substantially free of other textile materials are obtained.

5. Process for the recovery of wool fibers from mixed textile fibers containing wool and cellulose acetate fibers, which comprises immersing said fiber mixture in an aqueous solution containing 0.6% of sodium hydroxide and 20% of sodium sulfate for minutes at C. to cause the saponification of the cellulose acetate fibers and to yield regenerated cellulose, rinsing the fiber mixture, and then carbonizing the cellulose fibers from the fiber mixture by immersing the fibers in 6% aqueous sulfuric acid at 28 C. for 10 minutes, drying, baking the fibers at C. for 10 minutes, dusting, neutralizing, and rinsing, whereby wool fibers substantially free of other textile materials are obtained.

6. Process for the recovery of wool fibers from mixed textile fibers containing wool and cellulose acetate fibers, which comprises immersing said fiber mixture in an aqueous solution containing REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,804,529 Dreyfus May 12, 1931 1,980,191 Dickie Nov. 13, 1934 2,002,083 Dreyfus May 21, 1935 2,152,640 Ferguson Apr. 4, 1939 OTHER REFERENCES Mercerising Wool Mixtures-page of the Textile Manufacturer for April, 1943.