NL8102410A - PROCESS FOR PREPARING A TITANIC TANNING AND USE THEREOF IN A LEARNING TANNING PROCESS. - Google Patents

Description

-: 1 «ï N.0. 30,156

Process for the preparation of a titanium tannin and its use in a tanning process.

Applicants name as inventors: see after conclusions.

The present invention relates to methods of preparing mineral tannins and more particularly to methods of preparing titanium tannins from titanium iron-containing sulfate solutions and use thereof in leather tanning methods.

• In leather production, in addition to vegetable tanning substances, various mineral tanning substances are widely used, such as chrome, zirconium and aluminum compounds. Titanium compounds are also known to have tanning properties. Such titanium compounds are salts thereof, namely sulfates, for example, titanyl sulfate, chlorides, oxalates, gluconates, tartrates and lactates.

A known process for the preparation of titanyl sulfate involves the treatment of the titanium-containing starting material 15 with sulfuric acid, whereby titanium enters the sulfuric acid solution, from which titanyl sulfate is recovered by neutralizing the solution with lime, filtering off calcium sulfate and evaporating the filtrate ( see German patent 517,446).

However, this known method is complicated; it is difficult to get the product into a form suitable for its use as a tanning agent, and furthermore, the tannin thus obtained does not exhibit strikingly strong tanning properties.

A process is known in the art for preparing a titanium tannin from titanium ferrous solutions. This process involves adding an oxidizing agent to the starting ferrous sulfate solution, followed by addition of arammonium sulfate and sulfuric acid to precipitate a double salt of titanyl and ammonium sulfate in the raonohydrate form (NH ^ ^ TiOCSC ^ ^. ^ O, which then is stabilized by washing with a solution of ammonium sulfate (see USSR inventors certificate 668878, 1979). However, tannin prepared by this method contains an undesirable amount of impurities.

Also known in the art is a process for using this titanylammonium hydrogen sulfate salt for the tanning of decalcified and pecked skins, decalcified, peckled and chrome-treated skins (see U.S. Patent 3,93,9951) ♦ 81 02 4 1 0 B * 2

However, the leather obtained does not have the required quality properties.

It is an object of the present invention to improve the quality of a titanium tanning agent and to improve the tanning process, so that leather is produced with typically better quality parameters.

This object is accomplished in that, in a process for the preparation of a titanium tannin from titanium ferrous sulfate solutions, which comprises the addition of an oxidizing agent, it is followed by the addition of ammonium sulfate and sulfuric acid to prepare a double sulphate of titanyl and ammonium in the monohydrate form (NH 4 TiCKSQ 2 .H 2 O and subsequent stabilization of this salt by washing with a solution of ammonium sulphate, according to the present invention the oxidizing agent used is a sulfuric acid solution of a peroxy-titanium complex, which is added to the solution in an amount which ensures its residual content from 0.01 to 2 g / l calculated as titanium dioxide.

The use of the peroxy-titanium complex solution allows a mild oxidation and thus makes it possible to avoid over-oxidation of the starting solution and under-oxidation of the iron (II) therein. Therefore, the peroxy-titanium complex solution ensures an effective process for oxidation of iron under mild conditions, thereby improving the quality properties of the resulting tannin. The peroxy-titanium complex solution should be added at a rate that ensures the residue content of 0.01 to 2 g / l calculated as titanium dioxide. In this case, all the iron (II) present in the solution is converted into iron (III). Increasing the residue content of the peroxy-titanium-30 complex in the solution above 2 g / l based on titanium dioxide is undesirable since it causes a lower yield of titanium in the final product, while decreasing its content below 0.01 g / l l based on titanium dioxide is technologically unsuitable. Furthermore, the use of the per-oxy-titanium complex solution improves working conditions since this product is non-toxic.

According to the present invention, precipitation of tanyl ammonium hydrogen sulfate is effected prior to its formation in an amount of 75 to 85% based on ti-ifO tan dioxide, after which the precipitated salt is separated and washed 81 02 4 1 0 3 '*' ? the resulting filtrate and the resulting washings are combined and treated with ammonium sulfate to ensure post-deposition of the salt, which is then separated and recycled to the starting solution.

This method of precipitation contributes to an additional purification of the salt from the impurities which may be present in the solution.

Therefore, the advantage of the method of the present invention lies in that it permits the preparation of a tannin with a minimum content of iron (0.05% Fe 2 O 2 and lower) and other impurities. The process of the present invention makes it possible to use a sulfuric acid titanium ferrous solution with a higher content of iron therein, namely above 10 g / l FeO, while obtaining a high quality tannin. These advantages make this process more promising commercially compared to the prior art methods, while the use of the tannin prepared according to the method of the present invention allows to improve the quality of the tanned leather.

This object is also accomplished by a method for tanning descaled skins using the tannin prepared by the method described above, which method comprises treating skins with the tanning promoters selected from the group consisting of the sodium salt of disulfodinaphthylmethane , phthalic anhydride, aluminum alum, a mixture of aluminum alum with urotropin, ammonium titanyl sulfate and phenol oligomers dispersed in lignosulfonic acids, after which the skins are treated with the titanium tannin of the present invention.

The sodium salt of disulfodinaphthylmethane is added in an amount of 1.5 to 2.5 wt.% Of the skins, phthalic anhydride in an amount of 1.2 to 2.2 wt.% Of the skins, aluminum alum in an amount of 1 .0 to 3.0 wt.% Of the skins, a mixture of aluminum alum with urotropin in an amount of 1.8 to 5.0 wt.% Of the skins at a ratio between the mixing components ranging from 0.5 : 1 to 3.4 · 1, ammonium titanyl sulfate in an amount of 5 to 15% by weight of the skins, and phenol oligomers dispersed in lignosulfonic acids in an amount of 2.5 to 5% by weight of the skins.

In the case of using phenol oligomers dispersed in 8102410 k lignosulfonic acids, the skins are pre-treated with chromium.

The use of the tanning promoters of the present invention accelerates the tanning process, increases the temperature resistance of partially finished products, resulting in a better quality of the final leather, eg wear resistance of leather under dry conditions. 10 - 20% enlarged compared to the prior art.

The method of the present invention is also applicable to the tanning of decalcified skins, decalcified and pickled skins, decalcified, pickled and chrome-treated skins with a titanium tanning agent in the presence of an agent selected from the group consisting of lactic acid, aluminum alum, condensation products of synthetic fatty acids with triethanolamine. These agents are added to the tanning bath in an amount of 0.5 to 2.5% by weight of the skins. The partially finished leather obtained should preferably be treated with Nairit (chloroprene rubber) latex in an amount of from 1.0 to 6.0% based on dry matter (weight of the skins) before. improving the wear resistance of the final leather.

The use of these agents in titanium tanning tanning makes it possible to increase the mass yield of leather and to decrease its water absorption.

The method of the present invention makes it possible to produce slightly elastic leather with improved properties of wear resistance, water absorption and hygrothermal stability.

The titanium tannin of the present invention is prepared in the following manner.

A titanium ferrous concentrate is subjected to a sulfuric acid treatment. The treatment conditions, i.e. temperature, duration and acid concentration, depend on the composition of the concentrate used. The cake resulting from the treatment is leached with water using recycled liquids, titanium goes into the solution while being freed of insoluble impurities remaining in the residue. The precipitate is filtered off and washed with water, which water is then used for leaching as the recycled liquid.

An oxidizing agent is introduced into the titanium-containing sulphate solution obtained when the cake is leached; 81 02 4 1 0 5 * as such oxidizing agent, use is made of a sulfuric acid solution of a peroxytitanium complex *. The peroxytitanium complex is obtained by oxidation of part of the starting solution obtained after leaching of the cake. The oxidation can be accomplished by any known oxidizing agent such as ozone, hydrogen peroxide, ammonium persulfate or by electrolysis and the like. The sulfate solution of the peroxy-titanium coraplex is added in an excess of 0.01 - 0.2 g / l based on TiO4 with respect to the stoichiometry amount necessary to convert iron (II) to iron ( III).

After adding the peroxy-titanium complex to the starting solution, ammonium sulfate and sulfuric acid are added to a total free ammonium sulfate and sulfuric acid content of 450 to 600 g / l. From the solution thus prepared, a double sulfate of titanyl and arammonium monohydrate is precipitated in the form of (NH2) 4. (SO 2 .H 2 O. The precipitation time under discontinuous process conditions ranges from 5 to 20 hours. The precipitation temperature of the salt is within the range of 12 to 30 ° C.

At a temperature above 30 ° C, a double anhydrous sulfate of titanyl and ammonium can precipitate, which is unsuitable for use as a tanning agent. The residue content of titanium in the solution after precipitation of the salt is 3 to 10 g / l TiO 2. The degree of recovery of titanium from the starting product to the salt ranges from 55 to 90% depending on the concentrate used.

The resulting salt is filtered and washed with a solution containing 300 to 450 g / l sulfuric acid and 180-300 g / l (NH ^ ^ SO ^) and used in an amount of 0.4 to 0.7 µ per ton of salt In this way the salt of impurities is purified 30. The filtered and washed salt is treated with a solution containing ammonium sulfate in an amount of 300 to 400 g / l at a consumption of 0.4 to 0.7 nr per ton. of the salt for stabilization of the monohydrate form of the salt Titanium salt is a white powder Under the microscope it is in the form of isotropic tetrahedral crystals The salt composition is as follows by weight: TiO 2 - 19-21; S0 ^ - 44-48; (NH ^^ O - 15-17,

Fe_0 not more than 0.05; insoluble residue not more than 0.3; the rest is moisture.

In the case of preparing a titanium tannin from titanium-40 ferrous sulfate solutions containing more than 15 g / l I * eO, 8102410 '. Another embodiment of the present invention can be used, wherein after the addition of a sulfuric acid solution of a peroxy-titanium complex to the starting solution, precipitation of the titanium salt is effected by means of ammonium sulfate and sulfuric acid to form the salt in an amount of 75 to 85% calculated as titanium dioxide. The total free ammonium sulfate and sulfuric acid content is within the range of 300 to 1000 g / l. The precipitated salt is separated and washed with a solution containing 350-450 g / l ammonium sulfate. The impurity iron content in the titanium salt is 0.03 to 0.05 ° / °

The resulting filtrate and the resulting washings are combined and treated with ammonium sulfate to a total ammonium sulfate and sulfuric acid content of 450 to 600 g / l before post-precipitation of the salt. The salt is separated and recycled to the starting solution, since the iron content therein is 2-3%. The degree of precipitation of titanium in this case is 13 -22% of its starting content. The yield of the titanium salt in the case of the use of a recycled product after three treatments is 95 - 98%. The titanium tannin prepared according to the method described above can be used for tanning skins. The tanning process is as follows. The skins obtained from the livestock products (leftovers, waste) are placed in a drum, water is poured on at a temperature of 23 to 26 ° C to a water-to-skin ratio of 1.2 and promoting the tanning agents are added thereto (percent by weight of the skins): sodium salt of disulfonaphthylmethane in an amount of 1.5 to 2.5% phthalic anhydride in an amount of 1.2-2.2 aluminum alum in an amount of 1 to 3 $, a mixture of aluminum-30 alum with urotropin in an amount of 1.8 to 50% at a ratio of the mixture components of 0.5 to 3.4 · 1 or ammonium titanyl sulfate in an amount of 5 to 15% ·

These promoters make it possible to accelerate the tanning process and to improve the bond between the titanium tanning agent and colla-35. This results in an increased tannin content in the leather, improving the leather quality; the mass yield has been increased together with a better wear resistance; the water absorption is reduced ......

After treatment with the promoters, the titanium 40 tanning is carried out. For this purpose, a titanium tannin is added in an amount of 4 to 6 wt.% Of the skins calculated as TiO2, and aramonium sulfate in an amount of 4 to 6 wt.% Of the skins. The amount of the tannin and the ammonium sulfate depends on the density and thickness of the skins. During drum rotation, tanning of the skins takes place in 18 - 20 hours. Then, the partially finished leather obtained is neutralized with sodium sulfite and urotropin, each of which is added in an amount of 3 * 5% by weight of the skins.

Neutralization is terminated when the pH of the partially finished leather is within the range of 0.05 to 4 * 5. Then the partially finished product is rinsed and tanned with synthetic tannins, which are added in an amount of 15 to 17 wt. Tannins based on the skins. The tanning is carried out at a water to skin ratio of 1 * 2 to 1 * 4 * and a temperature of 38 to 43 ° C over a period of 2 to 3 days.

The partially finished product thus prepared is rinsed, filled by dipping and filled. Dipping filling uses magnesium sulfate in an amount of 5 to 10 fat in an amount of 5 to 10%. The filling is accomplished using solid synthetic fillers. The further finishing treatments are carried out in a usual manner.

In the case of using decalcified, pickled and chrome-treated skins, the picking process is carried out by means of sulfuric acid in the presence of sodium chloride or ammonium sulfate. The consumption amount of the acid is 0.9 - 1 * 0 • wt.% Of the skins, which is of sodium chloride and ammonia sulfate

6-7 wt.% Of the skins, the water to skin ratio is 0.8 -30 1.0, the temperature is within the range of 18 to 20 ° C, the pH

of the partially finished product at the end of the pickling treatment is 3 * 8 - 4.5 (outer layer) and 5.0 - 6.0 (inner layer).

. The chrome treatment is carried out by means of a chrome extract in an exhausted pickle bath. The consumption amount of the chromium tannin is 0.4 - 0.5 wt / r of the skins. Then, the titanium tanning is carried out using a fresh bath in the presence of phenol oligorasated dispersed in lignosulfonic acids and used in an amount of 2.5 to 5.0% by weight of the skins. The further treatments are carried out as described above.

81 02 4 1 0 \ - 8

Lactic acid, aluminum alum and the condensation product of synthetic fatty acids with triethanolamine are supplied in an amount of 0.5 to 2% by weight of the skins during the tanning of decalcified skins, decalcified and pickled skins, decalcified, pickled and chromium-treated skins. These additions improve the. quality of the leather, in particular the wear resistance of leather is increased and its water absorption is reduced. After tanning, the partially finished leather product is drum-treated with Nairit latex in an amount of 1 to 6% by weight of the skins calculated on dry solids.

Example I

Preparation of a titanium tannin

A titanium ferrous sulphate solution is used in an amount of 1000 liters with the composition in g / l: is 15 TiO 2 - 100, H 2 SO 5 - 500, FeO - 15, and obtained on leaching the cake. To this solution is added a sulfuric acid solution containing 100 g / l of a peroxy-titanium complex based on TiO2 to its residue content of 0.01 g / l of TiO2, after which the precipitation of a salt is effected by addition of ammonium sulfate and sulfuric acid to the solution to a total free sulfuric acid and free ammonium sulphate content of 500 g / l. A double sulfate of titanyl and ammonium in the monohydrate form (NH ^) 2Ti0 (S0 ^) 2.H2 O is precipitated from the solutions · The degree of precipitation of the salt is 97 $ calculated for TiO2 · The precipitate is filtered, washed with a solution containing 300 g / l H2S0 ^ and 200 g / l (KH ^) 2S0 ^ used in an amount of 0.3 m ^ · Then the precipitate is treated with a solution containing ammonium sulfate in an amount of 400 g / l; 3 the solution is used in an amount of 0.25 m. The yield of end product is 48Ο kg. The product contains TiO2-20 in weight percent; SO4-46; (NH4) 20-16; Fe 2 O • 0.045; insoluble residue - 0.25; the rest being moisture.

Example II

A titanium ferrous sulfuric acid solution is used in an amount of 1000 liters; the solution has the following composition in g / l: TiO 2 - 120, H 2 SO 4 - 400, FeO - 20. To this solution is added a sulfuric acid solution containing 100 g / l peroxy-titanium complex based on titanium dioxide to the residue. content thereof in the solution of 2 g / l as calculated for 40 TiO2. The salt precipitation is carried out by adding 8102410 9 ammonium sulfate to form it in an amount of 80 with respect to titanium dioxide. The total content of free ammonium sulfate and free sulfuric acid is 40 ° g / l · The precipitated salt is separated and washed with a solution containing 400 g / l ammonium sulfate, used in an amount of 0.5 m · The obtained salt is obtained in an amount of 480 kg. The salt contains by weight percent: TiC 2 -20; SO4-47; (NH3 O-17;

Fe_0 - 0.04; soluble residue - 0.3, the remainder consisting of moisture «10 The filtrate obtained after separation of titanium salt and the washing liquors are combined (the volume is 1170 liters) and ammonium sulfate is added to the total amount of free ammonium sulfate and sulfuric acid of 600 g / l to ensure post-precipitation of the salt. The degree of precipitation of titanium is 15% of its starting content. The salt is separated by filtration to give 100 kg of the final salt, containing by weight percent: TiO2-18.12 e2 ° 3 2.5. The salt thus prepared is recycled to the starting titanium ferrous sulphate solution The yield of titanium salt in the case of using the recycled product after three treatments is 97 SS.

Example III

Method of tanning skins

The hides (residues, waste, etc.) from livestock are placed in a drum, water is added thereto at a temperature of 23-26 ° C until the liquid-to-skin ratio is 1.2, and then the sodium salt of disulfodinaphthyl -thane added in an amount of 2% by weight of the skins.

The treatment time of the skins with this solution in the rotary drum is 1.5 hours, after which a titanium tannin is added in an amount of 6 wt.% Of the skins calculated as TiO 2 and ammonium sulfate in an amount of 6 wt. $ of the skins. All these components are supplied in the dry state.

The skins are tanned for 20 hours during drum rotation. Then, the partially finished leather thus prepared is neutralized with sodium sulfite and urotropin, each added at 3.5% by weight of the skins. Neutralization is stopped when the pH of the partially finished product is 4.5. Then the partially finished product is washed with water and tanned again with synthetic tannins used in an 8102410 V w 10 amount of 17 wt% tannins based on the skins.

As synthetic tannins use is made of agents which are resistant to an acidic environment and to ammonium sulphate.

The tanning is carried out at the water-to-skin ratio of 1.4 and a temperature of 40 ° C for 2 days. The starting pH of the solution should not be less than 4. To minimize foaming after refill, a coating paste or sulfonation is used. slurry added in an amount of 0.8% together with the tannin.

Then the partially finished product is washed, filled by dipping and filled. The following compounds are used for the dip filling: magnesium sulfate or ammonium sulfate in an amount of 5%, lubricate in an amount of 8%. The backfilling is performed using solid backfills. Further finishing treatments are carried out in a usual manner. The leather thus prepared has the following properties: mass yield 102%, dry abrasion resistance 200 revolutions / minute, water absorption for 2 hours 45%

Example IV

Pre-descaled skins are placed in a drum, water is added at a temperature of 26 ° C to the water to skin ratio of 1.2 and phthalic anhydride is added thereto in an amount of 2.0% by weight of the skins . The further treatment of the skins is carried out under the conditions described in Example III. The leather properties obtained are similar to those specified in Example III.

Example V

The treatment of skins is carried out according to the method described in Example III, except that before tanning, the skins are treated with aluminum alum in an amount of 3% by weight of the skins. The final properties of the leather are similar to those mentioned in Example III. Example VI

Tanning of descaled skins is performed under the conditions described in Example III. Before tanning, the skins are subjected to a treatment with a mixture of aluminum alum and urotropin in an amount of 3% by weight of the skins at the ratio of the mixture components of 2.5: 1. 40 The final properties of the leather are similar to 8102410 11 mentioned in Example III.

Example VII

The tanning of descaled skins is performed as in Example III. Before tanning, the skins are subjected to a treatment with ammonium titanyl sulfate in an amount of 3% by weight of the skins. The final properties of the leather are similar to those mentioned in Example III. Example VIII

Pre-chrome-treated skins are subjected to a treatment with phenol oligomers dispersed in lignosulfonic acids in an amount of 3 to 5% by weight of the skins prior to tanning. The subsequent treatment of the partially finished leather product is carried out under the conditions described in Example III. The final leather has properties similar to those described in Example III.

Example IX

Descaled livestock skins are placed in a drum, water is added at a temperature of 2 ° C to the water to skin ratio of 1.2 and titanium tannin is added in an amount of 6% by weight of the skins are known as

TiO2 together with ammonium sulfate in an amount of 6% by weight of the skins. At the same time, lactic acid is added to the tanning bath in an amount of 0.8% by weight of the skins. The tanning time in this solution is 22 hours. Then, the partially finished leather product obtained is neutralized with sodium sulfite and urotropin, each in an amount of 3 * 5% by weight of the skins. Neutralization is stopped when the pH of the partially finished product is ,3. Then the partially finished leather product is washed with water and tanned again with synthetic tannins. The further treatment of the partially finished leather product is carried out as described in Example III. The use of lactic acid in the tanning process improves the final leather quality.

The mass yield is 105 %% the dry wear resistance is 210 orawen counts / minute, the water absorption for 2 hours is if5%

35 Example X

The tanning of decalcified skins is carried out as described in Example IX, except that after neutralization of the partially finished leather product, it is treated with Nairit latex in an amount of 3% by weight of the skins calculated on dry solids. The duration of treatment is 1 hour. The treatment will partially reduce 81 024 1 0

V V

12 finished product with Nairit latex significantly improves the wear resistance of the final leather - 250 revolutions / minute. Example XI,

Descaled and peckled skins are treated according to the method described in Example 5 IX with the addition of aluminum alum in an amount of 2% by weight of the skins. The final leather properties are similar to those of Example IX.

Example XII

Descaled and peckled skins are treated according to the method described in Example 10 IX with addition of aluminum alum in an amount of 2% by weight of the skins during tanning. After neutralization, the partially finished leather product is treated with Nairit latex in an amount of 2% by weight of the skins as calculated for the dry solids. The final leather-15 properties are similar to those of Example X.

Example XIII

Descaled, peckled and chrome-treated skins are treated according to the method described in Example IX with the addition of an agent containing a condensation product of synthetic fatty acids with triethanolamine in an amount of 1.0% by weight of the skins during tanning. The final leather properties are similar to those of Example IX.

Example XIV

Descaled, peckled and chrome-treated skins are treated as in Example IX with addition during the tanning of a condensation product of synthetic fatty acids with triethanolamine in an amount of 1%. After neutralization of the partially finished leather product, it is treated with Nairit latex in an amount of 2% by weight of the skins as calculated for dry solids. The final leather properties are similar to those of Example X.

The leathers prepared using the title tannin according to the previous examples III to XIV have the following physico-mechanical properties: tensile strength 26-31 MPa; rack 13-14 wear resistance (abrasion resistance), dry I8O-25O o.p.m.

wet 5.8-9.0 h / mm; 40 water absorption for 2 hours 42-45% hygrothermal stability 90-100%.

8102410 13 ^

Furthermore, the leather obtained using the titanium tannin according to the present invention is characterized by increased water resistance, sweat fastness, shape resistance and can be stored for a long time without losing its qualities.

8102410

Claims (11)

A process for preparing a titanium tannin from titanium ferrous sulfate solutions comprising the addition of an oxidizing agent to the starting solution, followed by the addition of ammonium sulfate and sulfuric acid for precipitation of ammonium titanyl hydrogen sulfate monohydrate (KH2) Ti0 ( SO 2 H 2 O and stabilization thereof by washing with a solution of ammonium sulphate, characterized in that as sulphating agent a sulphate solution of a peroxy-titanium complex is added to the starting sulphate solution to a residual content thereof of 0.01 to 2. g / l based on titanium dioxide. Process according to claim 1, characterized in that the precipitation of (M 2) 2 TiQ (SO 2) 2 H 2 O is carried out before its formation in an amount of 75 to 85% based on titanium dioxide, after which the precipitated salt is separated and washed, the obtained filtrate and the obtained washing liquors combine and treated with ammonium sulfate before post-precipitation of the salt, which is separated and recycled to the starting solution. 5. Method for tanning descaled skins, characterized in that the skins are first treated with the tanning promoters selected from the group consisting of the sodium salt of disulfodinaphthylmethane, phthalic anhydride, aluminum alum, aluminum alum mixed with urotropin, ammonium titanyl sulfate and phenol oligomers dispersed in lognosulfonic acids, after which the skins are treated with the titanium tannin. 4. Process according to claim 3, characterized in that as the tanning promoter the sodium salt of disulfodinaphthylmethane is used in an amount of 1.5 to 2.5% by weight of the skins. The process according to claim 3, characterized in that phthalic anhydride is used as the tanning promoter in an amount of 1.2 to 2.2% by weight of the skins. 6. Process according to claim 3, characterized in that the tanning promoter is to use aluminum alum in an amount of 1 to 3% by weight of the skins. Process according to claim 3, characterized in that the tanning promoting agent used is a mixture of aluminum alum with urotropin in an amount of 1.8 to 5 81 024 1 0 15. . - gives,% of the skins a ratio between the components ranging from 0.5: 1 to 3 »4: 1 8. Process according to claim 3, characterized in that ammonium titanyl-5 sulphate is used as the tanning promoter in an amount of 5 to 15% by weight of the skins. 9. Process according to claim 3, characterized in that phenol oligomers dispersed in lignosulfonic acids are used as the tanning promoter in an amount of 2.5 to 5% by weight of the skins. 10. Process according to claim 9, characterized in that the skins are treated with chromium before the treatment of the skins with phenol oligomers dispersed in lignosulfonic acids. 11. Method for tanning descaled skins, decalcified skins and peckled skins or descaled, peckled and chrome-treated skins, characterized in that the tanning is carried out using a titanium tanning agent in the presence of a complexing agent selected from the group consisting of lactic acid, aluminum alum and condensation products of synthetic fatty acids with triethanolamine, which complexing agents are added in an amount of 0.5 to 2.0% by weight of the skins. 12. Process according to claim 11, characterized in that the partially finished leather product from the tanning is treated with airlit (chloroprene rubber) latex in an amount of 1 to 6% by weight of the skins calculated as dry solids. --- oooOooo— Inventors: David Lazarevich M0T0V, Ljudmila Petrovna TJURKINA, Lidia Georgievna GERASIMOVA, Alexandr Ivanovich METELKIN, Isaak Grigorievich SHIRRIN ', Hina Ivanovna KOLESNIKOVA, Galina Grigorievna YAKUSHEVA, Maria MOVAUSHEVA, Maria BEL0K0SK0V, Vladimir Pavlovich PLOTNIKOV. 8102410