SU4556A1 - Method of tanning leather - Google Patents

Description

The proposed method for tanning leather refers to methods in which ammonium sulfate is used in a mixture with alkali and alkaline earth metal salts and fatty and aromatic sulfonic acids.

The method consists in that the skin in its raw form after the closure, as usual, is subjected to lime lime, hair is removed from them and they are loaded into vats or into a rotating drum into which the solution is pre-poured (iSHJo SOj. After a few hours an additional solution (MH4) 2 ZOD is added (the amount depends on the progress of work, but not less than 5%). The skin is in a drum for at least 10-12 hours in general (preferably at a temperature of up to 90 ° C). Ammonium sulphate decomposes excess lime in the skin by the reaction (NHJ0SO -j + Ca (OH) 2 CaSOj + 2MH3 + 2H2O; evolved ammonia is quickly absorbed by the water and then permeates the skin.The removed skin is neutralized with weak sulfuric acid (from / 2 to 1%) in vats or drums, and the reaction in the skin: 2 MNS - {- N., $ Oi (ISH)., SO4. After these operations, the skin is exposed to appropriate tanning agents. In this way, skin can be quickly prepared with great resistance to tearing.

To obtain softer skins, such as: chromium, scheche, huskies, suede, etc., no prior neutralization with acids is required; after the action of ammonium sulphate, the skin is immediately tanned. What is more, if, for example, chrome tanning is performed in the same way, then there is no need to add soda. In this case, the skin gets the color and color of vegetable tanning.

Sulfonic acids of both aromatic and fatty series in a mixture with ammonium sulfate and other ammonium salts with the addition of carbonic and other salts of alkali and alkaline earth metals are used as a softener. If oil sulphonic acids are taken with a content of up to freedoms: loit Y..5O.1 and other impurities, then it is equivalent to 1 kg of sulphate of gmmmonch and soda.

For the preparation of a superior mortar softener solution. In order to avoid salting out of fiery soaps, sulfonic acids separately neutralized by ammonia and a solution of some ammonia salts are prepared, then the required amount of neutralized sulfonic acids is diluted with water to a certain concentration and added to the solution of ammonium salts. It turns out a completely homogeneous, without settling, solution, which can be used as a softener. Experiments made by the author on chromic tanning of leather, dehairing, prominees and tanned without pickel, using the specified softener showed that after adding the pierced skin to the ammonium sulfate solution, after a few minutes, the skin begins to acquire the properties of a softened mole: the skin drops, blue and blue From the gold sulphurous soda disappear, the face becomes even and smooth, and after 30 minutes a completely good state of the dried gol was achieved, and the loss of the potassium substance did not occur at all. For more prolonged softening, the cinder was kept for several hours, as well as several days, for the determination of rotting it was kept for about 25 days. In the latter case, no rotting was detected during the indicated time. In this case, chrome tanning was carried out with high concentration solutions without a subsequent increase in concentration, as is done with a low concentration of chromium solutions; Rapid bleeding gave quite positive results both in terms of getting a smooth and smooth face, and in terms of skin quality. At full

duplicating the skin turned out to be full, soft, without nostril and lightness, the skin of ordinary chrome tanning.

When they are sul (|) atmonmonich, they are used for shedding hides from 1) sts; about ser1-I1CT) 1M soda forms and are contained in approximately one of the following compounds: MH;, SO ,, H, .S, rSH -. NH,) S, Ca (SH). ,, INaSH. Ma.SO., (.H,). S ,, O. ,, (MI,) o S, O,., CaS-.O:;, CaSo., Mn ,, S., O: ,, r-la.jSO:;, MaHSO., and other compounds | | And formed from the release of various organic acids from the skins: acetic acid, lactic, oil, formic, etc. This bath contains all the necessary compounds in order to the skin was washed without loss of the skin substance (in view of the absence of the fermentation process) and, at the same time, sufficiently loosened for better perception of tannins. This bath, in addition to softening the skin after the batch of skins, in view of the significant content of polysulfides, thiosulfates, and also hydrogen sulfide water, can serve as a restorative treatment for double bath chrome tanning (hydrochloric acid with hydrochloric acid).

In order to use a bath: - {Only once, it is possible to add any mineral or organic acids, as well as petroleum sulfonic acids, to the combination of these actions with double chrome tanning. If it is necessary to revive the bath, the skin impregnated with chromic acid (hydrochloric acid with hydrochloric acid) is placed in this bath and hydrochloric or some other acid is added as needed:

KoSgg From + 2 НС1 2Ка + 2СгОз-гН ,, О.

Chromic acid under the action of polysulfidos, calcium thiosulfates, sodium, ammonium and HoS in the presence of hydrochloric acid forms Cr C1,:

2СгОз- -б HCl-f-3 Ma., S, .Oa 2 CrCi; - | -Ma., SO, 4-3S + 3 HgO,

which gives the main ducting compounds of chromium 2 CrCI., 4- IMajSoO-i-H, O-2Cr (OH) Ci, H-SO, -i-S--2 NaCl, which is thicker than the skin. In this case, sulfur dioxide gas partly regenerates backing, i.e., results in acid sulfides and polysulfides in thiosulfates, etc. By setting the solution 5 to the bath as needed is neutral, you can use it

again to soften the leather and produce further tanning in a single way, using the ready basic solution of chromic alum Cr (OH) 5O |. In the latter case, due to the significant content of ammonium compounds in the skin, chromates and other chromium compounds of the cobaltyacc type can be formed. Thus, by alternation, it is possible to use the same bath with a single chrome tanning, as a softening bath,

and in the case of a two-bathing method, a cocoa bath for softening and for the reduction of chromic acid.

Prede (5 tons of patent.

1. A method of tanning leather using ammonium sulfate mixed with alkali and alkaline earth metal salts and with a fatty or aromatic sulfonic acid, characterized in that these mixtures are used to soften the ash skin and, as a reducing agent, during subsequent processing of the skin chromic solutions after treatment with or without pickel.

2. Acceptance of the specified in l. 1 method, characterized in that in order to apply a mixture of ammonium sulfate with salts and sulfonic acids for chrome tanning, mineral or organic acids or petroleum sulfonic acids are added to this mixture.