US1823467A - Preliminary tanning process - Google Patents

Description

Patented Sept. 15, 1931' UNITED STATES PATENT OFFICE BERNHARD QUENDT, or ESSEN, GERMANY PRELIMINARY TANNING rnocsss No Drawing. Application filed January 25, 1929, Serial No. 835,141, and in Germany July 19, 1926.

The present invention relates to a process for preliminary treating hides for promoting the tanning thereof and preparations therefor, and for which I applied for patent in Germany July 19, 1926. 4 A preliminary treatment of hides, for tanning, withalum and sodium chloride and in some cases by the addition of chrome alum is already known. tion tanning consists only in an acceleration of the tanning and perhaps in a special grain. Nevertheless the leather cannot be spoken of as purely bark tanned on account of the fact that it exhibits peculiarities which are absent from a bark tanned leather, tendency to stretch for example, p 4

It has now been found that the tanning particularly the vegetable tanning of hides may be accelerated without alteration in the character of the leather if in the preliminary treatment a water soluble condensation product ofan aromatic amine be added the salt of an-aromatic amine or preferably a water soluble condensation product of a secondary or tertiary aromatic amine be added to the alum and one or more neutral salts, for example to the alum and sodium chloride, or to the alum, Gla'ubers salt and sodium vegetable tanning liquid, or even to clear water.

By such preliminary treatment of the hides according to the present invention. the pene- 8 tration of the tan in the tanning, particularly the vegetable tanning, process is promoted and a better tanning is realized.

An example of the use of a salt of an aromatic amine-for the preliminary treatment of the hides under the present invention which serve well is as follows Example I The resulting advantage of such eomhina- I chloride, or to a quebracho-liquid, or other tion and are then .diluted at 5 Baum. To this solution is then added 5 parts by weight of 30% formaldehyde which forms a complex water soluble condensation product with the other ingredients.- In this solution the hides receive their preliminary treatment either in a tumbler-drum or in a suspending vat. In the tumbler-drum the treat- .ment lasts about 12 hours; if the hides are that character this, after it has been thoroughly tanned, is again washed and then dried and finished according to usual or approved methods .to bring the leather to its final colour, texture, grain or other'desired condition.

E wa'inple 2 5 parts by weight of dimethylaniline are condensed with 4 parts by weight of monochloracctie acid and 2 parts by weight formaldehyde (30%). The condensation product is mixed with 400 parts by weight of alum and 200 parts by weight each of Glaubers salt and sodium chloride. This also is employed as a solution of 5 Bauin. The trcatv ment and subsequent tanning is carried out in accordance with Example 1.

E sample 3 The condensation product given in Example 2, which is a viscous liquid, is added to clear water or, otherwise, to a quebracho liquid or other tanning solution having :1 strength of about .--l. to 23 lizuuu. The

Y proportion of the condensation product should be in the ratio of 0.5 to 0.3% by weight of the water or Tanning liquor. In this solib tion the hide is treated as in Example 1. but only for about 3 to 5 hours. The hides are afterwards placed for about 10 hours in a strong vegetable or other tanning solution of about 5 to H i-umu". Th further treatment then follows according to Example 1.

Example 4 The condensation product detailed in Example '2 is mixed with vegetable or other tanning solution and put into water in a suspending rat. The solution so made may by way of example. be a 0.5 to 0.3% by weight solution. and alsoby way of exampieu e mixture of the condensation product'arid'th'e solution may he in the proportions-otl-part by weight of the condensation product to from 1 to 4 parts by weight of the solution.

The hides remain in this-solution (as'in; Example 1) for about one to two days (2% 48 hours) after which they are tanned andtinally finished as in Example No. 1.

It this Example 4 is carried out ina tumbler-drum the tanner will know the weight of hide which can. he treated in a given druni and the conditions governinc'lthe water co'ntent thereof. He will therefore calculate the weight of the hide and add an' amou'nt of the mixture of the condensation product and eX-' tract equal in weight to l to 3% of the said weight of the hide to be treated'i'n ,the drum.

The hides will remainin the solution in-the drum for from fourto five hours.

r In some cases the preliminary treatment hereinabove referred to may be carried out prior to any treatment or between the treat ment of the hides in'the'fi'r'stand second. or second and third, or third and fourth tanning vats, the usual preparatory or'beam' house processes.

After the preliminary treatment as described and as detailed in Ekamples 1 to 4, the hides may be subjected' to the customary tanning processes using the ordinary strong tanning solutions, which it will be found will more quickly and effectually penetrate the.

hides preliminarily-treated by the process and with the preparations as described in this-invention.

The time of the tanning which is accelerated by the present invention will of course vary in accordance with the thickness and hardness of the hide.

As an example of how a condensation or product is prepared. 5 parts by Weight of dimethylaniline and 4 parts by weight of monochloracetic acid are so mixed by a stirrer in hot water that they are brought to a thin solution. This solution. is thenheated to 100 C. for 2 hours while being, stirred. The solution is allowed to cool down to 80 C. and then 2 parts by weight of formaldehyde is added. then stirred torabout 5 minutes and put into an autoclave and treated for about 3 hours at a pressure of -3 of an atmosphere over atmosphere. until the final product is welh thickened.

\Vhat I claim is:

1. Process for promoting the tanning of hides by SUlJjCCtlllg the hides, after the usual preparatory processes, to a preliminary treatment with a solution of a Water soluble nonsulphonated condensation product of an aromatic amine.

2. Process for promoting the tanning of hides by subjecting the hides, after the usual preparatory processes, to preliminary treatment] With-a mixture of neutral salts, and a water soluble non-sulphonated condensation product of an aromatic amine. 3 8. Process for promoting the tanning of hides by subjecting the hides, after the usual preparatory processes, to a preliminary treatment with a mixture'of alum a neutral salt, and a water soluble non-sulphonated condensation product of an. aromatic amine.

4. Process for promoting the tanning of hidesby subjec'tingthe hides, after the usual preparatory processes,- to aprelimina-ry treatment with a mixture of a water soluble nonsulphonatcd condensation product of an aromatic amino and a weak tanning solution. In testimony whereof, I- afiix mv. signature.

BERNHARD QUENDT.

The resulting mixture is

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