US1765199A

US1765199A - Process for depilating hides and skins

Info

Publication number: US1765199A
Application number: US46493A
Authority: US
Inventors: Bergmann Max
Original assignee: Individual
Current assignee: Individual
Priority date: 1925-02-12
Filing date: 1925-07-27
Publication date: 1930-06-17
Anticipated expiration: 1947-06-17

Description

Patented June 17, 1930 MAX nnnemuu, ornnusnnu; GERMANY H PROCESS FOR DEPILATING HHJES AND SKINS I 170 Drawing Application filed July 27, 1925, Serial No. 46,493, and in Germany February 12, 1925.'

The commonly employed means for removing the hair from hides and skins, such as lime-cream and other slackening means, for example mixtures of lime-cream and sodium sulfide, lime-creamand arsenic sulfide, lime-cream and sodium hydroxide, so dium sulfide alone, sodium hydroxide alone, sodium hydroxide" and enzymes, enzymes alone or other means for unhairing skins,

10 show theinconvenience that, at the same time as the produce the depilation of the hides and shins, they damage the hair and those portions of the hide or skin from which the hair has been taken ofd". I now have found that it is possible to avoid this inconvenience and to obtain nevertheless a perfectly satisfactory depilation oi the hides and skins it the hides and skins, prior to, the treatment with the commonly used slackening means, or dressing means as lime,

lime and sodium sulphide, lime and arsenic sulphide, and the like, are treated with substances which are also able to loosen the hair but do not injure the same. Substances 5 which are in first line suitable for this purpose are inorganic and organic nitrogen bases as'ammonia, ethylene diamine, piperidine, pyridine and ureas, and thecompounds of said nitrogen bases, as especially the sulphides of such nitrogen bases, and further soluble silicates, these substances being employed separately or mixed with one another. I have found that, if the hides and skins are-submitted to a treatment with solutions of the substances mentioned separately or in mixture prior to the treatment with the commonly used unhairing means, the hair or wool and the true skins or the portions of the hides and skins from which the hair has been taken oil are not injured at all so that the value of the same is considerably increased. The leather made from skins and hides from which the hair has been taken ed in this manner shows a fine, well adhering graincombined with good fullness and a special density without being rigid or brittle.

It has further been found that when the -hides and skins have been preliminarily with mixtures thereof the subsequent depilating process proper'canbe varried out in a fraction of the time which was hitherto necessary for the slackening process by means of lime-cream and the like. en cleansing and working the hid with a mixture of lime-cream and sodium sulphideit is, for instance, possible to reduce by a preliminary treatment of-the Mud described, the duration of the depilating process from 12 hours to half an hour. This efiect of the preliminary treatment is very surprising and peculiar. The advantage resides not only in the reduction of duration of the depilating process proper but at the same time in the very good preservation especially of the hair which results from the fact that the lime-cream or the like which impairs the hair acts upon the skin and hair only for a very short time. If the hides and skins prior to the action of one of the commonly used slackening means are treated with solutions of ammonium sulphide or other ammonia derivatives alone or in mixture with soluble silicates, so weak concentrations of these solutions can be used that they do not cause a serious loosening of the hair, and only in combination with one of the commonly used, subsequently applied slackening means they effect sufiieient depilation. A similar, altholfgh smaller effect is obtained if the soluble silicates are applied alone. But these products must always be applied prior to r the tanning process proper if the desired action upon the true skin shall occur Examples 0 f application 1. For unhairing or depilating a set of sheepskins or fleeces they are brought, after having been well soaked, into a solution which contains for one cubicmeter of water 4 10 liters of a technical-solution of ammonium sulphide with a content of 10% (NH S, and they are left in this solution for one day. The skins are then put in anaqu'eous liquor which contains 0,25 kilo of sodium sulphide for each cubicmeter of liquid and lime in such a quantit that it will be well in excess of saturatlon of the liquid. After one hour theskins will release the hair, quite readily, and skins and hair are absolutely uninjured.

Instead of the indicated liquid for the preliminary treatment a solution may be 5 used'which contains for one cubicmeter of water liters of% ammonia. Instead of the liquid containing lime and sodium sulphide, an aqueous liquor containing 15 kilos of lime and 1.75 kilos of arsenic sulphide for each cubicmeter may be used for the unhairing process or also any one of the other commonly used unhairing means may be employed.

2. For unhairing a set of calfskins they are brought into a solution which contains for one cubicmeter of water 10 liters of a technical ammonium sulphide solution with a content of 10% (NHQ S and 10 liters of commercial water-glass solution of 38 to 40 B. So much of the liquid is used that the skins are well covered. After one day the skins are washed for three hours in water which has to be renewed several times and they are then brought. into an aqueous liquid mixture carrying 10% of lime and 1% of crystallized sodium sulphide. After one day, or at the utmost two days (according to the thickness of the skins), they will release the hair readily, hair and skins being .quite uninjured, and the leather obtained after tanning possesses a well adhering grain and great-density.

For other hides and skins the process must be modified accordingly although it remains principally the same.

Instead of ammonia or ammonia derivatives, suitable organic nitrogen bases and derivatives of the same may be used, as for instance ethylenediamine, piperidine, pyridine, urea substances and the like, or other mildly" acting hair-loosening means either alone or in mixture.

Having now particularly described and ascertained the natureof my said invention, I declarethat What I claim is: 1

1. A process for unhairing skins and hides which comprises firstly treating the skins and hides with a watery solution containing a nitrogen base readily soluble in water 5 while giving it an alkaline reaction, and

then with an alkaline unhairing means. 7

2. A process for unhairing skins and hides which comprises firstly treating the skins and hides with a soluble compound containing a nitrogen base readily soluble in water while giving it an alkaline reaction and then with an alkaline unhairing means.

3. A process for unhairing skins and hides which comprises treating the skins and hides with a mixture of compounds containing'a nitrogen base readily soluble in water while giving it an alkaline reaction and with an alkaline unhairing means.

4. A process for unhairing skins and hides which comprises firstly treating the skins gen base readily soluble in water while givng it an alkaline reaction and then with an alkaline unhairing means.

5. A process for unhairing skins and hides which comprises firstly treating the skins and hides with a basic derivative of ammonia which 1 is readily soluble in water while giving it an alkaline reaction and then with an alkaline unhairing means.

6. A process for unhairing skins and hides which comprises firstly treating the skins and hides with a mixture containing a derivative of a nitrogen base which is readily soluble in water "while giving it an alkaline reaction, and an alkali metal silicate and thereafter with an alkaline unhairing means.

7. A process for unhairing skins and hides which comprises firstly treating the skins and hides with a mixture of" ammonium su lphide and an alkali metal silicate and thereafter with an alkaline unhairing means.

8. A process for unhairing skins and hides which comprises treating the skins and hides with a watery solution containing a nitrogen base readily soluble in water while giving it an alkaline reaction and with an alkaline unhairing means. i

9. A process for unhairing skins and hides which comprises treating skins and hides.

with ammonium sulphide and an alkaline unhairing means.

10. A process for unhairing skins and hides which comprises treating the skins and hides with a watery solution "of a basic derivative of ammonia readily soluble in water while giving'it an alkaline reaction, a part at least of the hydrogen of which is substi-- tuted by a hydrocarbon group, and with an alkaline unhairing means.

'l1- A process for unhairing skins and hides which comprises treatin skins and hides with ammonium sulphi e, and with a chemical slackening means containing lime.

'12. A rocess for unhairing skins and hides WlllCh comprises firstly treatin the skins and' hides with a mixture 0 ammonium sulphide and an alkali metal silicate, and thereafter with a chemical slackening-means containing lime.

In testimony whereof I have hereunto set my hand.

., DR. MAX BERGMANN.

and Hides with a basic derivative of a nitro- 7