US725648A - Process of tanning hides, skins, or other animal tissues. - Google Patents

Description

UNITED STATES PATENT OFFICE.

OTTO P. AMEND, OF NEW YORK, N. Y.

PROCESS OF TANNING HIDES, SKINS, OR OTHER ANIMAL TISSUES;

SPECIFICATION forming part of Letters Patent N 0. 72 5,648, dated April 21, 1903.

Application filed March 27, 1901. Serial No. 53,135. (No specimens.)

To all whom it may concern.-

Be it known that I, Orro P. AMEND, a citizen of the United States, residing in the city, county, and State of New York, have invented a certain new and useful Process for the Tanning of Hides, Skins, or other Animal Tissues, of which the followingis a specification.

After many experiments I have found that the nitrites of the leather-forming metals are eminently suited to the tanning or tawing of hides and skins. In a former application,filed January 28, 1901, Serial No. 44,704, I have described and claimed the preparation and use of new tanning liquors containing a nitrite of a leather-forming metal in an aqueous solution. The present invention is based on the discovery that such nitrites and salts of nitrousacid when introduced into or formed in tanning liquors (such as organic tanning liquors made from sumac, hemlock, gambier, quebracho, oak, and other barks and materials containing tannin) and metallic tanning liquors containing the leather-forming metals greatly improve,expedite,and cheapen the operation and that when used in aqueous solution upon the hide or skin which has'already been converted into leather such leather is thereby greatly improved. I have found, further, that by the use of a tanning-bath containing a nitrite of a leather-forming metal the operation of treating the hides or skins with dung or manure may be entirely dispensed with, as it is unnecessary, though of course it may be used if desired. I have also discovered that the skin may be tanned by my process without removing the hair and that if dehairing is desired the liming, dehairing, and subsequent removal of the lime may be performed either before or after the pelt or skin has been tanned in my solutions. If liming and dehairing are practiced, I prefor to remove the lime chemically by washing in a weak solution of an acid, such as muriatic or acetic acid. As nitrited tanning solutions readily penetrate hides and skins in any condition and have an affinity therefor in contradistinctiou to other non-nitrited solutions which are repelled by the skin or are repellent thereto, hides and skins intended for for purposes may be thoroughly tanned by my solutions without such preliminary preparations of puring (or treatment with dung) and degreasing, and the process results in a leather which is much stronger than that produced by tawing liquors, which do not contain the nitrites of the leather-forming metals and are tawed without any appreciable shrinkage of the hide or skin, while in addition such skin will stand a higher degree of heat in the dyeing of its hair or fur than leather produced by other processes, and, furthermore, there Will be no appreciable shrinkage in the dyeing operation.

In practicing my invention I first prepare an aqueous solution containing a nitrite of one of the leather-forming metals-chromium, iron, and aluminium-and such solution may be formed in several ways. Thus, for instance, I dissolve a salt of one of such metals in water at ordinary temperatures. I also dissolve a soluble nitrite of an alkali metalsuch as nitrite of sodium, nitrite of potassium, &c.-,or of an alkaline earth, such as nitrite of barium, in water at ordinary temperatures and then mix the two solutions containing a nitrite of a leather-forming metal. In some cases there will be an insoluble precipitate formed, together with a solution of a nitrite-of the leather-forming metal contained in the metallic salt, while in other cases no precipitate will be formed, but a partial decomposition takes place witn the formation of a nitrite of the leather-forming metal in the solution. In the former instance t-he precipitate may be removed by filtration or decantation, as is well understood, while in both cases it is the solution containing the nitrite of the leather-forming metal that furnishes the tanning agent. As illustrations of the first class of solutions I dissolve seven hundred and seventeen (the molecular weight) grams of crystalline chromic sulfate, Or,(SO,) -|-l8(H O,) in about seven thousand grams of Water at ordinary temperatures. I also dissolve six hundred and eighty-seven (three times the molecular weight) grams of barium nitrite, Ba(NO in about seven thousand grams of water at ordinary temperatures. I then mix the two solutions and remove the insoluble precipitate. The clear solution will contain nitrite of chromium and is the tanning liquor to be used. Again, I dissolve three hundred of the latter.

and sixty-nine (the molecular weight) grams of chromium oxalate, Cr (O O,) in about four thousand grams of water at ordinary temperatures. I also dissolve three hundred and ninety-six (three times the molecular weight) grams of calcium nitrite, Oa(NO in about four thousand grams of water. I then mix the.

two solutions and remove the precipitate. The clear solution will contain nitrite of chromium and is the tanning liquor to be used. Of course the salts may be mechanically mixed first and then dissolved in water. As illustrations of the second class of solutions I have found that when I mix an aqueous so lution of a chlorid acetate, formate, or nitrate of one of the leather-forming metals with an aqueous solution of a nitrite of an alkali metal or of an alkaline earth no precipitate may be formed, but a reaction occurs, forming an aqueous solution containing a nitrite of a leather-forming metal, which is the tanning agent to be used. I have also found by experiment that I can form an efficient and cheap tanning solution of the second class by the use of chrome-alum, K Or (SO +24(H O,)as follows: Idissolve chromealum in, say, ten parts of Water at ordinary temperatures and add to this solution a solution of sodium nitrite in, say, ten parts of water at ordinary temperatures, the proportion of chrome-alum to sodium nitrate being one molecule of the former to six molecules There will be no precipitate formed in this solution, but there will be a reaction with the formation of nitrite of ohromium in the solution.

Although I have specified chromium as the leather-forming metal in' all of the foregoing examples and prefer to use it, Ido not confine myself to the use of the salts of this metal; but my invention includes the use of the salts of the other leather-forming metalsiron and aluminium. Where the salts of iron and aluminium are used, the same proportions and formulas as those given above for the use of chromium will be efficient, of course observing the difference in molecular weight; nor do I confine myself to the use of the specific nitrites of the alkali metals named, but include the use ofany soluble nitrites of an alkali metal or of an alkaline earth and also the use of nitrogen trioxid (N 0 and oxids of nitrogen, which are convertible by reduction or oxidation into nitrogen trioxid, (N O such as nitrogen tetraoxid, (N O in the one case, and nitrogen dioxid, (N 0 in the other case, in Whichever way they are applied to the leather-forming metal or its salts for the formation of a tanning-bath containing a nitrite of a leather-forming metal in aqueous solution. Of course when desired in compound metal tanning the salts of two or more leather-forming metals may be used, so as to form the corresponding nitrites in the tanning solution. In practice, for instance, I take for every one pound of chrome-alum one-half pound of nitrite of sodium and dissolve the salts in water in proportions of fromone part of the mixed salts to eight parts of water,

according to the strength of the solution de-' tanning with chromic sulfate and barium nitrite I take for every one pound of chromic sulfate, Cr (SO +-IS(H O,) one pound of ba rium nitrite, Ba(NO and dissolve the salts in water in proportions of from one part of the mixed salts to eight parts of water, up to one part of the mixed salts to eighty parts of water, according to the strength of the solution desired, and so on for the other salts of the different leather-forming metals. I have found four ounces of chromium nitrite to each gallon of water to bean efficient tanning liquor.

Of course my invention contemplates and comprises all methods of introducing into the bath or generating within the bath a nitrite of a leather-forming metal. For instance, I

can introduce into a bath containing chrome hydrate in suspension a stream of nitrogen trioxid (N 0 through a tube in quantities sufficient to dissolve the chrome hydrate. Nitrite of chromium will be formed in the bath.

My invention contemplates several diiferent methods of using my tanning'solutions, thus, first, subjecting the skins or hides to the action of an aqueous solution containing a nitrite of a leather-forming metal and subsequently subjecting the skins or hides to the action of an organic tanning liquor such as is made entirely from sumac, oak, hemlock, and other barks and materials containing tannin; second, subjecting the hides or skins to the action of an aqueous solution containing a nitrite of a leather-forming metal, and subseqently subjecting the skins or hides to the action of a metallic tanning-bath in which the nitrite ofa leather-forming metal is not present; third, subjecting the skins or hides to the action of an organic tanning liquor into which a nitrite of a leather-forming metal or nitrogen trioxid (N 0 or an oxid of nitrogen which is convertible by reduction or oxidation into nitrous oxid has been introduced; fourth, subjecting the skins or hides to the action of a metallic tanning liquor containing a nitrite of a leather-forming metal or a metallic tanning liquor into which a salt of a leather-forming metal and either (a) a nitrite of an alkali metal or of an alkaline earth or (b) nitrogen trioxid (N 0 or (c) an oxid of nitrogen which is convertible by reduction or oxidation into nitrogen trioxid (N 0 have been introduced; fifth, subjecting the skins or hides which have been previously tanned in an organic tanning liquor to the action of a nitrite of a leather forming metal or the materials for forming such nitrite in aqueous solution, or, sixth,

subjecting the skins or hides to the action of an ordinary metallic tanning liquor, and sub-.

sequently subjecting them to the action of a nitrite of a leather-forming metal or materials for forming such nitrite in aqueous solutions.

The following are methods of practicing my invention: In cases where skins have already been tanned either in organic or metallic tanning liquors I subsequently subject them to the action of one of my above-doscribed liquors containing a nitrite of a leather-forming metal, and the resulting imfor in all cases such proportions of the tan-' ning metal and nitrogen trioxid (N 0 should be used as to form the nitrite of the leatherforming metal used. In cases where the skin has not been tanned and where it is desired to tan it by the conjoint use of an ordinary tanning liquor (organic or metallic) and my liquor containing a metallic nitrite I proceed in one of the following ways: (a) I prepare an ordinary organic or an ordinary metallic tanning liquor by the ordinary methods and introduce into it one of my tanning liquors containing a nitrite of a leather-forming metal. Effective proportions to be used are one part of one of my liquors to ten parts of the ordinary tanning liquor. (b) If the metallic tannage only is desired, I can prepare an ordinary metallic tanning liquor in the usual way and introduce nitrogen trioxid (N 0 into it mechanically.

In all cases and under all conditions the object of my invention is to subject the skins or hides, tanned or untanned, to the action of a nitrite of a leather forming metal, whether such nitrite be used in any ordinary tanning-bath (organic or metallic) or in a liquor which is used subseqent to the use of an ordinary tanning liquor, (organic or metallic,) and my invention contemplates all methods of forming such nitrites of the leather-forming metals and all proportions in which they may be used in or with the tanning liquor.

If one of my tanning liquors is used in connection with an organic tanning liquor and (a) is introduced into the organic tanning liquor itself, the organic tanning liquor may be weakened to one-tenth of its usual strength, and the proportions for the actual tanning bath may then be, for instance, ten parts of the weakened tanning liquor to one part of my tanning liquor. The skins or pelts will be tanned in about one-tenth of the time required for tanning in the ordinary organic tanning-bath by itself. liquors is used (b) subsequent to the use of the ordinary tanning-baths, (either organic or metallic,) the ordinary tanning-baths should be of their usual strength, and the skins or hides may be immersed in one of my tanningbaths from one to twenty-four hours, according to the thickness, character, and quality of the skin. If one of my tanning liquors is If one of my tanning used in connection with one of the methods of ordinary metallic tannage and is introduced (a) into theliquor of a single metallic tanning-bath process, the proportions may be, for instance, ten parts of the ordinary tanning liquor of the ordinary strength to ten parts of one of my tanning liquors.

For the purpose of the following claims it is immaterial and it is an equivalent use of my invention whether the nitrite of the leather-forming metal is contained in the ordinary tanning liquor (organic or metallic) itself or is used in a separate liquor in which the skins or hides are previously or subse-' quently immersed.

Having thus described my invention, what I claim is- 1. The process of tanning which consists in exposing the skin or hide to the action of a nitrite of a tanning metal in solution, and the ingredients of an ordinary tanning liquor in solution, substantially as described.

2. The process of tanning which consists in exposing the skin or hide to the action of a nitrite of a tanning metal in solution, and the ingredients of an ordinary metallic tan;

ning liquor in solution, substantially as described.

OTTO P. AMEND. Witnesses:

HARRY V. FOUNTAIN, JAMES M. STEWART.