US2393712A - Recovery of wool from mixed woolcellulose acetate textiles - Google Patents

Description

Patented Jan. 29, 1946 RECOVERY OF WOOL FROM MIXED WOOL- CELLULOSE ACETATE TEXTILES George W. Seymour and George C. Ward, Cumberland, Md., assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application March 10, 1944, Serial No. 525,953

3 Claims. (01. 8 -1 10) 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 removed in an economical and convenient manner.

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

In textile operations involving the use of wool and cellulose acetate or other organic esters of cellulose yarns, there is produced 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 tothe recovery of the wool is to remove the non-woolen materials. Mixtures of wool and cellulose acetate or other organic ester of cellulose, are however, not amenable to the usual separation or carbonization treatments such as those employed for removing cellulose materials from wool. Such treatments have no effect on cellulose ester materials since the cellulose esters difier substantially from cellulose materials in their physical and chemical properties. Not only must a process for separating wool and cellulose acetate materials be effective and ecomay be recovered from a fiber mixture comprising wool and fibers having a basis of cellulose acetate, or other organic ester of cellulose, by

impregnating the fibers with an aqueous solution of an organic swelling agent for the cellulose acetate fibers containing an inorganic carbonizing agent, drying the fibers, and then baking the dried fibers at elevated temperature. The swelling agent causes the cellulose acetate fibers to swell and enables the inorganic carbonizing agent to penetrate the cellulose acetate fibers and, during the baking operation, the carbonizing agent effects a carbonization of the cellulose acetate fibers. Following carbonization, the fibers are washed and the wool fibers which were originally present are recovered in a satisfactory condition and in full possession of their original textile characteristics and properties.

Suitable swelling agents which may be employed in treating the fiber mixture are, for example, ethyl alcohol, acetone, isopropyl alcohol, butyl alcohol, methyl ethyl ketone and ethyl lactate. Satisfactory swelling action may be eifected when the swelling agent is present in the aqueous solution in concentrations of 5 to 50% by weight. While all of these swelling agents are suitable, we preferably employ ethyl alcohol, and

optimum results are achieved with aqueous solutions containing from 15 to 35% of this alcohol.

Various inorganic carbonizing agents having a carbonizing action on cellulose acetate materials may be employed. Preferably, we employ inorganic mineral acids such as sulfuric acid, hydrochloric acid or phosphoric acid, e. g. orthophosphoric acid, but inorganic agents such as aluminum chloride, which yields hydrochloric acid by hydrolysis and on heating, may also be employed. When employing sulfuric acid, concentrations of 4 to 8% by weight of the acid in the impregnating solution containing the organic swelling agent are suitable.

' The penetration of the cellulose acetate fibers by the carbonizing agent, is effected by maintaining the fiber mixture in the aqueous solution of swelling agent containing the carbonizing agent for 2 to 20 minutes at 20 to 50 C. The fiber mixture isthen removed from the aqueous solution, dried and baked for 5 to 30 minutes at to C. The cellulose acetate fibers are carbonized during the baking operation and, after washing with water, the wool fibers in the initial fiber mixture are recovered in unchanged form and in full possession of their original valuable textile properties.

Furthermore, we have found, for example, that when employing aqueous solutions containing ethyl alcohol as the swelling agent and sulfuric acid as the carbonizing agent, a substantial reduction in the amount of swelling agent employed may be effected if a hydrohalic carbonizing acid, e. g.hydrochloric acid, is also added to the aqueous impregnating solution. Thus, when employamples are given:

ing from 2 to 5% by weight of hydrochloric acid in the solution, we may-employ a decreased amount of ethyl alcohol, say. 5 to 15%. in the waste materials comprising wool and cellulose acetate materials to recover wool fibers free of said materials, mixtures of wool, cellulose acetate and cellulose fibers are commonly encountered in commercial operation 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 ex- Emamplc I A mixture of textile fibers comprising 65% by covered wool fibers retain their original textile properties and may be employed-again for all textile applications.

Example [I A mixture of textile fibers cm nsmg 65% by weight of wool, 28% of cellulose acetate fibers, and 7% of cellulosic fibers is immersed in' an aqueous bath comprising 25% by weight of ethyl many novel and decorative effects may be obtained by weaving a fabric of wool and cellulose acetate yarns orfibers and then removing all of the non-woolen fibers.

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

It is to beunderstood that the foregoing detailed description is given merely by way of innstration 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:

1. Process for the recovery of wool from mixed textile materials containing wool and cellulose acetate fibers, which comprises immersing said mixture of fibers in an aqueous bath containing from 5 to 15% of ethyl alcohol, from 4 to 8% of sulfuric acid and from 2' to 5% of hydrochloric acid until penetration of the cellulose acetate fibers is effected, drying thefiber mixture, and

. baking the dried fibers at elevated temperature,

alcohol and 6% of sulfuric acid. The fibers are maintained therein for 15 minutes at 30 C. and

are then removed from the bath, dried, and baked at 110 C. for 10 minutes. After washing, the fibers remaining comprise pure wool fibers free of all cellulose acetate and cellulosic fibers. The recovered wool fibers possess their usual textile properties and may be employed again in the preparation of woolen and worsted materials.

It is to be understood, of course, that our novel process maybe applied to any textile material. suchas, 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,

whereby the cellulos acetate fibers are carbonized and wool fibersfree of other textile materials are obtained.

2. Process for the recovery of wool from mixed textile materials containing wool and cellulose acetate fibers, which comprises immersing said textile materials containing wool and cellulose acetate fibers, which comprises immersing said mixture of fibers in an aqueous bath containing from 5 to 15% of ethyl alcohol, from etc 8% of sulfuric acid and from 2 to 5% of hydrochloric acid for 2 to 20 minutes at 20 to 50 0., drying the fiber mixture, and baking the dried fibers for 5 to 30 minutes at to (7., whereby the cellulose acetate fibers are carbonized and wool fibers free of other textile materials are obtained.

GEORGE W. SEYMOUR. GEORGE C. WARD.