US1753539A - Process of unhairing hides and skins - Google Patents

Description

I Patented Apr. 1930 UNITED STATES PATENT OFFICE.

HARRY M. ULLMANN AND EDWIN R. THEIS, F BETHLEHEM, PENNSYLVANIA rnocnss or UNHAIRING HInns AND SKINS No Drawing.

This invention relates to a process of unhairing hides and skins involving the use of the pancreatic enzymes. For brevity in the following description only hides will be referred to, it being understood that animal skins generally are meant unless otherwise indicated. Theunhairing of hides, i. e.,' the skins of large full grown animals, such as steer hides, is the principal application of the invention, Also for the sake of brevity only stance, it has been proposed to subject hides to be unhaired to a preliminary swelling in an acid or alkaline solution and thereafter 5 tov subject the hides to the action of pancreatin until unhairing occurs, that is, until the haircan be removed, for instance bysliding a finger over the hide. This treatment, however, works an undesirable degenerative so and destructive action upon the hide, in-

cluding digestion of the derma.

Our process is, in a sense, a modification .of the so-called liming process. It is not designed to and does not eliminate liming but has the advantage that it greatly shortens the customary lime treatment. In the customary liming process cured hides are first soaked in-water for about 24 hours toremove salt and are then put into a solution of lime for about 120 hours, more or less, depending upon the kind and condition of the hide and other factors after which the hair may be removed in the known way. It will be understood that our process as described .is adapted to the treatment ofcured or salted hides, although it readily may be modified and adapted to the treatment of fresh or uncured hides.

Accordingto the process of our invention,

the cured hides are not subjected to any pre- Application filed December 26, 1928. Serial No. 328,619.

liminary swelling in acid or alkali nor to a preliminary and independent soaking as in the Well-knownliming process but the pancreatin is added directly to the Water used for. soaking the hides. Thus it may be considered that the customary soaking is replaced by a treatment with pancreatin or more logically that the treatment with pancreatin is superimposed upon or combined with the customary soaking, It is desirable, although not essential, that the pancreatin beadded at the beginning of the soaking. The soaking in the presence of pancreatin is continued for about the customary length of time, say 20 hours, (this period of time may vary with the'condition, cure and 'kind of hide, the temperature of operation, the concentration and activity of the pancreatin in the bath, etc.) and the hide is then trans ferred to the customaryliining liquor where it is left for only a comparatively short time, say 20 hours, after which it is ready for the usual mechanical treatment for removing the loosened hair. It is noted'that the hide is not left in the pancreatin-containing soaking bath until unhairing occurs, i. e., until the hair may be removed by sliding a finger over the hide. Indeed'the hair should be still tight at the end of the soaking treatment. Due to the great variation in hides, it is impossible to specify precise conditions for the treatment of all hides. We prefer-for the sake of economy to use a dilute solution of pancreatin for the combined pancreatin and soaking treatment, for example -.02% to 04% of pancreatin based on the weight of the soaking Water or solution. Higher concentrations of pancreatin up to say 0.1% may be usedwith a shortening of, the treatment. The concentration of pancreatin in the soaking solution may vary from a minimum effective quantity, the lower limit apparently being in the neighborhood of .0l% up to that quantity which in a given time will deleteriously aifect the hide. F or example, a 1% solution acting upon steer hide at. 70 F. for 20 hour-s ordinarily detrimentally affects the hide. f

The temperature, about 60 F. to F., and other conditions observed in the modified soaking and liming operations are the same as those used in the customary soaking and liming operations, the only variations being those referred to above, i. e., that the soakinilwater has pancreatin added to it and the soa 'ng operation is limited, if necessary, to avoid detr mental action upon the hide, it

(being unnecessary to'loosen the hair by the action of the pancreatin in the soaking bath, and the liming treatment is limited to a time sufiicient to loosen the hairthe usual effect of liming. o

The treatment described does not result in any appreciable degeneration of the derma of the hide. Net gains in hidedue to hydration and the amount andiqnality of the finished leather are normal .as-compared with the product obtained by the known soaking and liming process.

We claim: 1. Process of unhairing hides which comprises soaking thehides inwatercontainmg 'pancreatin and thereafter liming the soaked hide.

2. Process of unhairing hides which comprises contacting the hides with a solution of pancreatin for a substantial period of time insufiicient to produce unhairing and thereaftei' treating the hides with a solution of lime until the hair is loosened.

3-. Process of unhairing hides which comprises soaking cured hides in the presence of pancreatin in quantity amounting to from about 02% to 0.1% of the soaking liquid for a substantial period short of time suflicient to produce unhairing and thereafter subjecting the hides to a short liming treatment.

4. Process of unhairing hides which com- I prises soaking cured hides in the presence of pancreatin in quantity amounting to from .02% to 04% of the soaking liquidfor about 20 hours at a temperature of from Flto F. and'thereafter liming the hides for about 20 hours.

In testimony whereof, we aflix our tures.

. signa- HARRY M. ULLMANN.

EDWIN RTHEIS.