US2101511A - Sole leather and process of preparing the same - Google Patents

Description

Patented Dec. 7, 1937 I UNITED, STATES PATENT OFFICE SOLE LEATHER AND PROCESS OF PREPAR- ING THE SAME Otto Darmstadt, Germany No Drawing. Application June 29, 1936, Serial No. 88,057. In Germany July 2, 1935 6 Claims. (01. 149-4) The invention relates to improvements in sole In order also to make the exterior of the new leather and the process of preparing the same. type of leather simulate bark-tanned leather as Most sole leathers are nowadays prepared with much as possible, bichromate may be added to the the aid of vegetable tanning agents. The special sulphite cellulose extract,- thus producing a properties of bark-tanned sole leather are: limleather having a browncolor. In lieu of bichro- 5 ited permeability to air, limited water absorption mate, other oxidation agents may be used. capacity, rapid giving off of water under pressure, limited content of water-soluble substances, and Example definite Specific gravity- Furthermore, bark- Hides which have been limed, hated, and pick- 10 tanned leather increases in strength when it is led in the usual manner are fulled in a. barrel 10 rolled under heavy pressure, whereas mineral for two days of eight, hours each t tanned leather becomes softer under such treat- Percent me Th s p p t s a of importance in Sulphite cellulose extract of 28-30 B. (calworking up the leather for shoe soles and during ated on the'weight of the hides) 50 the wearing of the shoes. During the working Sodium or potassium bichromate 1 15 up of the leather the important points are that w te 25 the leather can be sewed and nailed, that the nails hold, and that the cut portions can be finished with a nice gloss. Bark-tanned leather produces,

After this period the leathers remain lying on the block for two days. Thereupon they are fulled for two days ofeight hours each with:

as the worker in the art says: a good finished 2 trim. When being worn, the properties are man- Percent o ifested by the fact that the wearer does not skid sulPmte cellulose F fi of B 50 on bark-tanned soles in wet weather, and that sodmm Potasslum bmhmmate 1 the soles, when they become wet, do not swell water 25 25 and thus alter the Shape of the shoes' After storing for two days the leathers are fulled In order first to shorten the duration of the for four hours with a solution of:

tanmng process and, secondly, in order to be in- Percent dependent of the importation of foreign vegetable Formic acid (85% tanmng agents, the workers in the art have for waterglass solution having 25% sioz 10 many years attempted to substitute mineral tan- Water i 15 3o ning agents for vegetable tanning agents in the preparation of sole leather, but without appreciuntil all of the liquor is taken p- The a e s able success. are stored overnight on the block.

The reason for the lack of success is that the N morning a mixture of p fl P1115 vegetable tanning agents impart the above recit d 2.5% tetralin is fulled into the leather while in the 35 special properties to the leather and these results greasing V The leathers. which h e cannot be achieved with the mineral tanning stored on the floor over ni t a e la d out the agents. Even sulphite cellulose extracts have n xt m n d d Working up p ds in been tried and have been mixed with i l the same way as in the case of bark-tanned sole 40 tanning agents but without result.- leather. 40

- It ha be n found that a ol l th can be According to the above recited process oxidizobtained in a few days by using a, c mbi ti ing agents such as bichromate are described as employing sulphite cellulose extract, acidified 51- -used together with the sulphite cellulose extract,

licic acid solution and a small amount of fatty and the pr s so arranged h he lea hers are substances and that such leather possesses all fu ed w t ac d silicic d s o I 45 of the properties of bark-tanned leather. The It has alsobeen found that a greatly improved chemicals required in producing this leather need sole leather is obtained if the silicic acid is not not be imported from abroad. used subsequently but rather, under certain con- The method is as follows: ditions, along with the sulphite cellulose tanning The hides, cleaned as usual, are fulled with sulprocess and in such fashion that the hides are 50 phite cellulose extract, then treated with an acidfirst treated with a sulphite cellulose extract ified alkali silicate solution and impregnated with liquor. without addition of silicic acid and then a. little hard grease such as tallow, paraflin, carfirst with sulphite cellulose liquor containing nauba wax, synthetic waxes, etc., with or without added silicic acid. Immediately thereupon the the addition of solvents. leathers are filled with silicic acid solution as de- 55 with hard greases or waxes or, prior to drying, r

they may merely be oiled with neats-foot oil.

The process may with advantage be supplemented by adding small amounts of othertanning agents, such as alum tanning agents, chrome tanning agents, vegetable tanning agents, or synthetic tanning agents, in order to vary the basic character of the leather.

Examples 1. l-Iides which have been limed, hated, and pickled as usual are fulled in a barrel for two days of eight hours each in:

Percent Sulphite cellulose extract of 28-30 B. (calculated on hide weight) Water- 25 After this time the leathers remain lying on the block for two days. Thereupon they are again, fulled for two days of eight hours each in a fresh liquor of Percent Sulphite cellulose extract (of 28-30 B.)--- 50 Concentrated formic acid 2 Waterglass solution having 25% S10: 10 Water 25 After storing for two days the leathers are fulled for 1 to 2 hours with a solution of:

until all of the liquor is taken up. The leathers are stored over night on the block. This fulling may be repeated 1 or 2 times. After the last fulling the leathers are again stored over night on the block; and the next morning washed off on both sides with water, laid out, and oiled with neat s-foot oil on the grain side.

2. The procedure is that as given in Example 1, with the feature that in preparing the 1st and 2nd tanning liquors 1.5% of chrome alum is added. A sole leather of pleasant color shade is obtained.

3. The procedure is that as given in Exa le. 1, with the feature that in preparing the 1s and 11d a ing iq ors. p tash alum is added.

A rapid, thorough tanning results and the leather produced has good quality and good tearing strength;

4. The procedure is that as given in Example 1, with the feature that in preparing the 1st and 2nd tanning liquors, 10% aluminum formate is added. An especially water-resistant leather is obtained.

5. The procedure is that as given in Example 1, with the feature that in preparing the 1st and 2nd tanning liquors, 1% of commercial synthetic tanning agent is added, such as a condensation product of naphthalene sulphonic acid and formaldehyde.

The invention has been described in detail for the purpose of illustration but it will be apparent that modifications or variations of the process may be resorted to without departing from the spirit of the invention claimed.

I claim:

1. A process for preparing sole leather which comprises first tanning hides with sulphite cellulose extract before any silicic acid is added, and in a subsequent step filling with silicic acid solution.

2. A process for preparing sole leather which comprises first tanning hides with sulphite cellulose extract before any silicic acid is added, and in a subsequent step filling with silicic acid solution, and treating with a member of a group consisting of oils, greases, and waxes.

3. A process for preparing sole leather which comprises first tanning hides with sulphite cellulose extract and an-oxidizing agent before any silicic acid is added and in a subsequent step filling with silicic acid solution.

4. A process as set forth in claim 3, wherein the oxidizing agent is a member of a group consisting of sodium bichromate and potassium bichromate.

5. A process for preparing sole leather which comprises first tanning hides with sulphite eellulose extract before any silicic acid is added, then treating with sulphite cellulose extract and silicic acid solution- 6. A process for preparing sole leather which comprises first tanning hides with sulphite cellulose extract before any silicic acid is added, then treating with sulphite cellulose extract and silicic acid solution, and in a subsequent step filling with silicic acid solution.

OTTO RHlVI.