US837105A - Process for dyeing leather. - Google Patents

Description

UNITED STATES PATENT OFFICE.

PROCESS FOR DYEING LEATHER.

Specification of Letters Patent.

Patented Nov. 27, 1906.

Application filed January 21, 1905. Serial No. 242,068.

To all whom it may concern:

Be it known that I, FRANCIS J. OAKES, a citizen of the United States, and a resident of the borough of Manhattan, city, county, and State of New York, have invented a certain new and useful Process for Dyeing Leather, of which the following is a specification.

The objects of my present invention are to produce a process which will obviate the injurious effects upon the leather incident to the application of the present processes for dyeing same and which result in imparting too much brittleness to the surface of the leather, removing undesirable portions of its tannin, and failing to impart a color of sufificient permanence and intensity.

I attain the objects referred to by the hereinafter-described processes, in which I utilize the reactions realizable between the constituents of an alkaline sulfid and compounds of a metal capable of combining in the presence of resulting hydrogen sulfid to form an insoluble compound of said metal as,for inst ance,a sulfid thereof or a hydroxid' after which, if desired, the leather may be still further treated by applying thereto a coloring-matter capable of forming a lake with the aforesaid resulting compounds of said metal.

An example of my novel process and its method of application is as follows: The leather after being stuffed or fat liquored is brushed over with a dilute aqueous solution of a soluble alkaline sulfid-for instance, a two-and-one-halfer-cent. solution of an ammonium sulfi (N H) Sx. It is then while still moist further treated by being brushed over with a solution of a metallic compound or saltfor instance, an acetate of iron F62 OH3OOO 6 or Fe(CH COO) such a solution consisting of, say, one hundred arts of water containing ten parts of socalled black iron. After the treatment described the leather is allowed to dry, and after a moderate exposure to the atmosphere is ready for the usual finishing processes.

While the foregoing application of my process results in a dye sufficient for many purposes, it is often desirable for specific purposes to impart to the leather a more intense or permanent color, in which case the leather while still moist and before the drying above referred to is additionally brushed over with an aqueous solution of any desired dyestuffas, for instance, say, tenpercent.

nent.

solution of logwood extract-after which it is dried, as aforesaid, and is ready for the usual finishin processes.

It will be understood that the proportions and quantities of the agents employed may be varied according to requirement, as will be readily ascertained and appreciated by those skilled in the art.

It seems that the alkaline sulfid reacts with the fat liquors and grease in the leather to form alkaline salts, with a resulting liberation of hydrogen sulfid, which is retained partly in consequence of the moist conditions. On the application of the solution containing the compound of the metal there results in the presence of such hydrogen sulfid a reaction resulting, among other things, in the formation of a sulfid of said metal, or, should the latter be, for instance, chromium or aluminium, in the formation of a hydroxid thereof. These finally resulting compounds of the metals introduced are of exceptionally soft and plastic character and owing to this quality tend to fill up the pores of the leather and correspondingly improve its quality, diminishing brittleness, &c. In cases where additional coloring-matter or dyestuff is added by a third brushing over of the leather, as aforesaid, such coloring-matter or dyestuff should be of such character as to be capable of forming a lake with the metallic compound formed, as aforesaid.

The color produced by my said process possesses the advantage of being exceptionally resistant to the action of oxidizing and reducing agents and correspondingly perma- Another noticeable advantage resulting from my process is seen in the comparatively harmless action of the alkaline sulfid on the fiber of the leather, such sulfid acting merely as a mild alkali to cut the grease.

My process is applicable to all grades of leather and whether tanned by means of organic or mineral agents. It is advantageously applicable without the aforesaid final application of additional dyestuff to leathers prepared with tannic acids, in which case a very good black may be secured, though there may occur in this case comparatively more undesirable oxidation. As any coloring-matter complying with the aforesaid requirements may be employed in the final brushing, it will be appreciated that a large range of shades may be imparted.

Having thus described my process, what I claim as new, and desire to secure by Letters Patent, is the following, viz:

1. The process of dyeing leather Which consists in a plying thereto, While moist, an alkaline suliid, and also a metal capable of combining, in the presence of hydrogen sulfid, to form an insoluble compound of said metal, substantially as and for the purposes described.

2. The process of dyeing leather which consists in applying thereto While moist, an alkaline sulfid and also a metal capable of combining, in the presence of hydrogen sulfid, to form an insoluble sulfid of said metal.

3. The process of dyeing leather Which consists in applying thereto, While moist, a solution containing an alkaline sulfid, and also a solution containing a compound of a metal capable of combining, in the presence of hydrogen sulfid, to form an insoluble compound of said metal.

4.. The process of dyeing leather which consists in applying thereto, while moist, a solution containing an alkaline sulfid and also a solution containing a compound of a metal capable of combining, in the presence of hydrogen sulfid, to form an insoluble sulfid of said'metal;

5. The process of dyeing leather which consists in applying thereto, While moist, a

solution containing ammonium sulfid and also a solution containing a salt of iron.

6. The process of dyeing leather which consists in applying thereto, While moist, a solution containing ammonium sulfid and also a solution containing acetate of iron.

7. The process of dyeing leather which consists in applying thereto, While moist, an alkaline sulfid, also a solution containing a compound of a metal capable of combining, in the presence of hydrogen sulfid, to form an insoluble compound of said' metal, and also a coloring-matter capable of forming a lake With the resulting compounds of said metal.

8. The process of dyeing leather which consists in applying thereto, While moist, an alkaline sulfid, a solution containing acetate of iron, and also a solution of logWood extract.

9. The process of dyeing leather which consists in applying thereto, While moist, an alkaline sulfid, and also a metal capable of combining, in the presence of hydrogen sulfid, .to form an insoluble compound of said metal, substantially as and for the purposes described.

10. The process of dyeing leather which consists in applying thereto an alkaline sulfid and also a metal capable of combining, in the presence of hydrogen sulfid, to form an insoluble'sulfid of said metal.

11. The process of dyeing leather which consists in applying thereto, While moist, a solution containing ammonium sulfid and also a solution containing a compound of a metal capable of combining in the presence of hydrogen sulfid to form an insoluble sulfid of said metal.

12. The process of dyeing leather which consists in applying thereto, While moist, a solution containing ammonium sulfid, also a solution containing a compound of a metal capable of combining, in the presenceof hydrogen sulfid, to form an insoluble sulfid of said metal, and also a coloring-matter capable of forming a lake with the resulting compound of said metal.

FRANCIS J. OAKES.

Witnesses WALTER D. EDMONDS, ALLEN ROGERS.