US937720A - Process of tannng skins and hides. - Google Patents

Description

- Alsace, Germany,

of the skin 'UNITED STATES PATENT OFFICE.

.. nanny sum,

or MiITLHAUSEE-GEBMANY, nssrenon TO THE FIRM, or c. H.

:Bonnnmenn'sonn, or manna menm nm, GERMANY.

937,720 f 2R0 Drawing.

To all iplwm 'it my camera: Be it known that. I, HENRY SCHMID,

chemist, a citizen of the Swiss Republic, re-

siding vat Salvatorstrasse, Miilhausen, -m have nvented certain new m- Processes of and useful Improvements of which the fol- Tanning Skins and Hides, lowing 1s a specification.

My present invention relates to improvements in the art of tanning skins and hides by means of metallic oxids, and it has for its object primarily to provide an improved process of this character whereby the leather obtained is unusually strong and is capable of being quickly dyed, the metallic oxids being so intimately introduced into the fiber The methods hitherto known of this kind of tanning and of tawing hides and skins had in view a combining of the animal skin with ametallic oxid or basic metallic oxid of the formula Me O 'Invchrome tanning, for instance, the skins are impregnatedwith a basic chromic salt. In the. same. measure as chromic oxid or hydroxid is fixed on the fiber, acid is set .at liberty, for instance ac--. cording 'to the equation wherein a sesquioxid-may also be-combined with two oxids MeO, or several. ses uioxids with each other or with a MeQoxi viz or,o +'A1,o,I. or o wam, A1' o,+Fe o, I +Me0 +Me0 +Me0 have affinities for pigments which are unknown or at least-have not been utilized in connection with simple oxids. They also produce'lakes of greater intensity and higher resisting power due, it. seems, that the combined oxids adhere more trongly to the fiber and therefore combine with it more intimately. Such binary and Specification of Letters ZPatent.

as to render them perfectly fast.

I Water,

Such have M to the fact rnoenss or 'rnnnrno sKms AND nrnns.

Patented Oct. 19, 1909.

Application filed December 4, 1907. Serial No. 405,026.

ternary compounds are, for instance, compounds of. the formulae Cr O MgO, and

'Al O MgOZnO. Experiments made with these combined mordants in mineral tanning demonstrate .that a particularly strong leather is obtainable which permits an unusually fast dyeing, especially when fast mordant-dyesare employed.

According) to the present" invention the hides may first tanned in the ordinary way, for example, with a basic salt of chromium ,oxid such as a basic sulfate or a basic chlorid of chromium, but instead of neutralizing the acid thus set free by 'means ofborax' or alkali silicate or the like, as has been said is usual in the known processes, the hide is now treated with the alkaline solution of another'metallic oxid insoluble in tion of sodium zincate Zn(ONa) Thus the following reaction would take place:

but the whole reaction, including the chromic salt, may be re resented for instance by the following equa ion:

for instance, with an aqueous solu- I Thus the soda of the sodium zincate or'a partof it combines with the portion of the:

acid radical not already neutralized, both 'chromic oxid and zinc oxid being set free and ,preci itated simultaneously in the skin. As a resu t, a more complete action of the chromic oxid is obtained and, moreover, this chromic'oxid is more intimately combined with and enriched by the zinc oxid,

Xed on the skin or hide than are the simple oxids. By the formation 'of this dou 1e dye-lake a more intense, lastingand-deeper coloring is effected with a smaller quantity i of dye.

Instead of using a sodium zincate solution, other solutions might be. employed wh ch have 'a similar chemical action. For instance, a solution of aluminate of soda or an ammoniacal solution of copper of chemically equivalent quantities might be employed, and in such case the followingreaction probably takes place:

Al(ONa)L,-l'-3 HC1=A1(OH) +3 N501. A similar action will takeplace when using thecompound thus produced being-more intimately I a solution of copper oxid in ammonia, but an exact chemical equation of the reaction which takes place in the latter instance cannot be given because such ammoniacal solutions of copper are not of uniform composition. By using the turkey red" oils the accordance with my present invention, the

following may serve as an mstance which will enable those skilledinthe art to practice the invention. After the skins or hides have been prepared for tannin that is to say, after they havebeen washed, depilated,

and freed of lime, they are placed in a bath of basic chromic chlorid of 1 Baum.

l About every fifteen minutes so much chrome extract is added that the concentration of the tanning-bath is increased by 250.25 or 0.5 Baum each time, until it has reached about 3- Baum. By chrome extract is meant mixtures conslsting chiefly of basic chlorid of chromium-or of basic sull fate of chromium or of a mixture of these chrome salts. Such mixture may also con- 1 I tain chlorid of sodium or. sulfate of sodium, according to the method of preparing the extract; By cutting through a portion of the skin, the condition thereof may be de- "termined, and when a "sample cut indicates that the skins are completely tanned throughout the thickness, they are taken from the bath and transferred to a bath containing a sodium zincate-solution of 2 Baum. Eve

Y 40 20 minutes so much sodium zincate is added that the concentration of the bath' is increased by 0.5 Baum each time, until it has reached 4Bai1m, 80 minutts being 1 {thus required for the treatment; The skins 4501' hides are thenwell washed and subsequently worked in. the usual manner.

The combined use of salts of different I metals such, for, instance, as acetate of aluminium or chromium with those of limevv 50. or magnesia, has been racticed heretofore.

Such prior'processes di er from the present invention in the following respects: Ac-

cording to the present invention, basic metallic saltis exposed to the action of the metallic salt dissolved in caustic alkali; By

the reaction,

1 Cr(OH) ,,+Zn(OH)'(ONa) NaCl, to a thorough and immediate deacidifica'tion of the basic salt takes lace until an insoluble compound,or a meta lic hydroxid, separates,

and at the same time the oxid dissolved in alkali is set free and is deposited on the fiber. ofthe skin in'such an intimate rela- 'of'metallic salts, which consists in im regtion therewith as to render it very adhesive. The metallic salts absorbed by the skin are I thus deacidified and precipitated by means of a suitable alkalinedouble compound such, for instance, as sodium zincate Zn(ONa) sodium aluminate Al(ONa) and at the same time, the ecipitated oxid, such as Cr(OH) ,,is enrlched by. the oxids which are se arated from the alkaline double compoun s. Thesodium aluminate is employed in exactly the same manneras has been described in the case of sodium zincate. As a result, the oxids are sointima'tely' embodied in the skin as to render them perfectly fast, the results being superior to the previous method of neutralizing the basic salts by an alkali or byinsoluble carbonates such, for instance, as prepared chalk.

Another advantage obtained by the present invention is, that a larger percentage of the various metallic oxids is introduced into the fiber of the skin, therebyincreasing the percentage of tanning metallic oxid.

.I'claim as my invention I 1. The herein described process (of tanning skins and hides by means of metallic salts, which consists in impregnatin the prepared skins and hides wlth the so ution of a basic salt .of a sesquioxid, and then treating the impregnated skins and hides with the alkaline solution of another metallic oxidinsoluble in water. i 1 2. The herein described im rovement in the art of tanning skins and hides by means nating the pre ared skins and hideswit the solution of a asic salt of a sesquioxid, and then treating the impregnated skins. and

hides with the alkaline solution of another metallic .oxid of the formulalMeO insoluble inwater.v

3. The herein described'im provement in the art-of tanningskins and hides by means of metallic salts, which consists in impregnating the prepared skins and'- hides with the solution of a basic salt of a sesquioxid, and then treating the impregnated skins and hides with an alkallne solution of sodiumzincate. v

5 4. The herein described improvement in, the art of tanning skins and hides by means of metallic salts, which consists in impregnating the prepared skins and hides with the solution of a basic salt of a sesquioxid, and then treating the impregnated skins with the alkaline solution of another metallic oxid insoluble in water in which a soluble oil is dissolved.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

' I HENRY SCHMID.

Witnesses:

W. A. LEONARD,- WILH. Gonna.