US1089797A - Tanning material. - Google Patents

Description

UNITED STATES RHINE, GERMANY, A CORPORATION.

PATENT OFFICE.

OTTO SCHMIDT AND JULIUS MULLER, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, I

ASSIGl-NORS T0 BADISGHE ANILIN & SODA FABRIK,

OF LUDWIGSHAFEN-ON-THE- TANNING MATERIAL.

To all whom it may concern Be it known that we, O'rro SCHMIDT and J ULIUs M'tiLLER, subjects, respectively, of the King of Prussia and the King of Bavaria, residing at Ludwigshafen on the Rhine, Germany, have invented new and useful Improvements in Tanning Materials, of which the following is a specification.

. In the Annalen dew Ohemie (vol. 178, 1875, pp. 171 et seq.) Schifi' has described the production of condensation products from 'phenol-sulfonic acid by heating it either with a large excess of phosphorus oxychlorid at from 50 to 60 0., or by itself at about 200, C. at ordinary pressure, and states that theproducts are solid, and insoluble in dilute acids, and that," when used as tanning agents, they convert skins into a brittle leather. The leather obtained is practically Worthless and consequently the compounds described by Schifl have not been used commercially for tannin".

We have now found that by heating a phenol-sulfonic acid under mild conditions we can obtain products which, in contradistinction to those described by Schifi', are eminently adapted for use as tanning agents especially in the manufacture of leather. Under "the term a phenol-sulfonic acid we include the sulfonic acids of phenol and of homologues thereof, particularly the cresols. During the production of the new compounds, water is split 0H and condensation takes place, and We prefer, especially in the case of using phenol-sulfonic acid, to carry out the condensation under diminished pressure. If desired, a condensation agent '(such for instance as phosphorus trichlorid, phosphorus oxychlorid, or thionyl chlorid) can be added, during the reaction, or, if desired, the products obtained by condensation without t e addition of such an agent can be subsequently treated therewith. When employing phenol-sulfonic acids, no excess of the condensation agent should be employed, since otherwise products may be ob tained which, like Schiifs aforesaid prod- Specification of Letters Patent. Application :flled January 21, 19-13.

Patented MarnlO, 191st. Serial No. 743,297.

nets, are not suitable for tannin" purposes. When working with phenol-sulfonic acids at ordinary pressure, the temperatureshould not exceed about 150 C. for any length of time. When producing tanning agents from cresol sulfonic acids, the conditions obtain ing need not always be so mild as is desirable in the case of phenol sulfonic acids.

The products obtained according to this invention are probably bodies which are less' highly molecular than those obtainable according to the method described by Schitf, and, when employed for tanning skins or hides, full white leather of great softness and pliability can be obtained. As a general rule, the products of this invention are thick non-crystallizable syrups, but some approach a solid state on being cooled and a few of those obtained from cresol sulfonic acids can be obtained in the solid state. Their alkali salts are colorless, amorphous and readily solublein water, yielding intense colorations with ferric chlorid and iron alum and, after the addition of acid, coagulate gum solution. The free acids are also generally soluble in dilute acids. Either the free acid or the alkali salt, in the presence of acid, is suitablefor tanning skins or hides, and they can be used, if desired, in admixture or conjunction with other tanning agents. Our new tanning agents contain sulfur and are also practically free from diphenylmethane compounds; consequently, on treatment in cold aqueous and slightly alkaline solution with a small quantity of alcoholic tetrachlorquinoue, no coloring matter is formed.

The following examples will serve to illustrate further the nature of this invention, which, however, is not confined to these examples. The parts are by weight.

Example 1: Heat phenol para sulfonic acid at a pressure of 20 mm. and at a temperature of 130 0., for about 24 hours, or take test portions from time to time, dissolve them in water and add gum solution. When the precipitation which then occurs no ample.

' in the cold, see

longer increases in quantity, the reaction is finished. The reaction product can be directly employed for tanning, or it can be purified by dissolving it in water, neutralizing with caustic soda solution, filtering and evaporating the filtrate to dryness, whereupon a white powder is obtained which rapidly dissolves and gives a clear solution in water. By ferric chlorid, the aqueous solution is colored red-violet. After acidification, it gives a considerable precipitate with gum solution. Skins or hides which have been tanned with a solution of the acid, or the acidified salt, are colored orange by iron alum.

Example 2: Heat, for 7 2 hours, at a pressure of 20 mm. and at a temperature of 140 (3., the product obtained by heating phenol gently with concentrated sulfuric acid, which consists principally of phenol-parasulfonic acid together with some phenolortho-sulfonic acid. Work up the reaction product as described in the foregoing ex Example 3: Heat ortho-cresol-sulfonic acid (obtainable by sulfonating orthocresol Berichte 20, 3210) at a pressure of 20 mm. and a temperature of 130 C., for about 24 hours, or until a test portion, on being dissolved in water and on the addition of gum solution, shows that no further increase in the precipitation takes place. Then take up the product with water, filter,- neutralize the filtrate with caustic soda and evaporate to dryness. The product is readily soluble in water and the solution is colored' red-violet by ferric chlorid. After acidification, it yields a considerable precipi- -tation with gum solution. By heating the product with dilute sulfuric acid, cresol is split off.

Example 4: Heat 1,000 parts of crude cresol-sulfonic acid at a pressure of about 20 mm. and at a temperature of 130 0., for about 24 hours, until a test portion shows that the reaction is complete. Then cool to about 80 C., add 186 parts of phosphorus trichlorid and stir for 1 hour at this temperature and at ordinary pressure. Then take up the product with ice and water, allow it to stand for some time and work up as described in the foregoing Example 3.

' The product is similar to that obtained according to the said Example 3.

Example 5: Heat together 3 parts of crude cresol-sulfonic acid and 1 part of paraphenol-sulfonic acid for 48 hours in cacao, at a temperature of 133 C. When the mixture is cold, dissolve it in 18 parts of Water, allow the solution to stand for some hours, filter it and then nearly neutralize the filtrate, so that about 5%of acid remains unneutralized. Cool in ice for 2 hours, filter weave? and evaporate to dryness. The product thus obtained is a light brown mass which rapidly dissolves in water and gives a copious precipitation with gum solution.

Example 6: Heat 225 parts of the sulfonation product of crude "cresol with 262.5 parts of phosphorus oxychlorid for 4 hours at 60 G. Then distil off the excess of phosphorus oxychlorid, and wash the product with hydrochloric acid.

Example 7 Dissolve,1n water, the product obtained according to .the foregoing Example 3 and, if necessary, acidify it slightly, but not to such an extent that the skins or hides swell too much. The solution should have a density of about 0.6 B. Then hang the well-limed and bated skins or hides in the solution andgradually increase the quantity of tanning material and acid until, at

the end of 10 days, the solution has a density of about 5 B. The process of tanning requires about 14- days. The leather is then neutralized and treated with fat and dried, which 'may be done in the usual manner. The leather is of excellent quality and does not become brittle on drying.

Either but one tanning bath can be employed or a series of two, three, or more such baths of difierent strengths can be employed, so that the skins or hides are subjected to the successive action of stronger tanning solutions.

Instead of employing the hanging process, the skins or hides can be tanned in other manner, for example according to'the paddling process, or in a drum, and in these cases the tanning liquid is preferably employed, from the start, in a more concentrated form, for instance from 2 to 4 B., and is subsequently also gradually strengthened. In this way complete tanning can be efiected in from 6 to 8 hours, according to the material being tanned. In a simllar manner, the tanning materials obtained according to others of the foregoing examples can be used for tanning.

Now what we claim is 1 1. As new articles of manufacture condensation products obtainable from a phenol-sulfonic acid, which new compounds contain sulfur, are practically free from diphenylmethane compounds, and in the form.

ferric chlorid and, after the ad- 1 sulfuric acid splits ofi' cresol, and in the set our hands in the presence of two subform of its alkali salts is practically colorscribing witnesses.

less, amorphous and readily soluble in Water OTTO SCHMIDT yielding solutions which give intense c0lorations with ferric chlorid and after the addi- JULIUS E tion of acid coagulate gum solution, and Witnesses:

which tan hides giving a useful leather. JOSEPH HEIFFER,

In testimony whereof We have hereunto J. ALEC. LLOYD.