Classifications

• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
  • C14C3/00—Tanning; Compositions for tanning
  • C14C3/02—Chemical tanning
  • C14C3/04—Mineral tanning

Definitions

• the present invention relates to a new process of tanning hides by means of tanning agents containing iron.
• aliphatic hydroxy acids such as glycolic acid and polybasic, in particular dibasic, acids or their watersoluble salts, as for example sulphuric acid, malonic acid, tartaric acid, citricacid, oxalic acid, phthalic acid and their salts.
• Phosphoric acid and its salts as for example secondary sodium phosphate, may also be used with advantage.
• iron complex compounds which are capable of forming two-shell complexes in the said manner, there may be mentioned for example those formed by the reaction of iron chloride with alkali salts of weak organic acids, as for example formic acid, acetic acid, hydroxyacids, such as lactic acid, and amino acids, in aqueous solution, for example the nitrogenous complex salts to be used according to the application Serial No. 90,918, filed on July 16th, 1936, now Patent No. 2,122,133.
• Hexaacetato-dihydroxy-tri ferric salts and hexaformiato-dihydroxy-triferric salts are also suitable.
• the ratio of the complex iron acid and base present in the tanning liquor corresponds approximately to the ratio of the basic and acid places of the hide.
• the acids or salts capable of being enclosed in the second sphere may be added to the original cationic iron complex salts in the tanning liquor itself, or these and also the anionic two-shell complex salts may be allowed'to form by mutual dis solution of the components in the tanning liquor.
• the two-shell complex anions and the one-shell complex cations it is preferable to allow the two-shell complex anions and the one-shell complex cations to act on the hides in such amounts as correspond to the proportion of basic and acid spots in the hides.
• Tanning by the said process takes place rapidly and uniformly; the unhaired hides generally speaking need not be neutralized after the tanning because they are stable to plumping by hot water directly after the tanning.
• After rinsing with warm water they may be fat-liquored with the usual fat emulsions and prepared in the usual manner, as for example as russet leather.
• the leather dries soft and full. If desired the resulting leather may be further treated with aftertreatment agents generally used in tanning.
• Example 1 100 parts of unhaired cattle hides which have been pickled in the usual manner are moved in the vat with a solution of 100 parts of water, 12 parts of hexa-acetato-dihydroxy-bicarbamidotriferric chloride, 3 parts of anhydrous sodium sulphate and 1 part of sulphuric acid of 66 Baum strength until the unhaired hides have been completely tanned through. This operation takes from 8 to 20 hours depending on the thickness of the unhaired hides. A leather of uniform section is obtained having a firm, smooth grain which without aftertreatment possesses the valuable property of not plumping. After storing overnight, the leather is rinsed in water at 30 C.-
• Example 2 parts of unhaired cattle hides which have been pickled in the usual manner are drummed with a solution of 5.7 parts of anhydrous iron chloride, 5.8 parts of anhydrous sodium acetate, 2.5 parts of urea, 3.5 parts of anhydrous sodium sulphate and 1 part of .sulphuric acid of 66 Baum strength in 100 parts of water until complete tanning through is effected.
• the leather is rinsed, fatted and prepared directly after tanning. A leather similar to that in Example 1 is obtained.
• Example 3 100 parts of unhaired cattle hides which have been pickled in the usual manner are drummed for from 8 to 20 hours with a solution of 12 parts of hexa acetato dihydroxy bicarbamido-triferric chloride, 3 parts of potassium oxalate and 0.5 part of sulphuric acid of 66 Baum strength in 100 parts of water. After tanning through, the leather is stored for a day, rinsed for half an hour at 30 C., fatted and prepared in the usual manner, a leather having a beautiful pale colour being obtained.
• Example 4 The procedure described in Example 3 is followed, except that the potassium oxalate is replaced by 3.5 parts of secondary sodium phosphate. After rinsing, fatting and preparation, a leather is obtained which is very full especially in the sides.
• Example 5 100 parts of unhaired calf hides which have been pickled with 0.7 part of sulphuric acid of 66 Baum strength drummed in the vat for 8 hours with a solution of 8 parts of hexa-acetato-dihydroxy-tricarbamido-triferric chloride, 2 parts of sodium phthalate and 0.5 part of sulphuric acid of 66 Baum strength in 100 parts of water. After the said time the unhaired hides have been tanned through with the exhaustion of the tanning liquir. After rinsing, fatting and softening,
• Example 6 100 parts of calf hides pickled in the usual manner with 0.7 per cent of sulphuric acid are drummed with 100 per cent of water, 5 per cent of sodium chloride, 12 per cent of hexa-acetatodihydroxy-bicarbamido-triferric chloride and 1.5 per cent of glycolic acid until the taning is complete. Then neutralization is eifected with 2.9 per cent of sodium carbonate. The leather is washed with water, fat-liquored and finished in the usual manner. The leather possesses a good resistance to hot water (shrinkage 5 per cent).
• the process for the production of leather which comprises treating hides with a solution of an iron complex compound capable of having acidradicals enclosed in the second sphere of its complex, in the presence of a substance selected from the class consisting of the acids capable of being so enclosed and the water-soluble salts of such acids.
• the process forthe production of leather which comprises treating hides with a solution of a polynuclear iron complex compound capable of having acid radicals enclosed in the second sphere of its complex, in the presence of a substance selected from the class consisting of the acids capable of being so enclosed and the watersoluble salts'of such acids.
• the process for the production of leather which comprises treating hides with a solution of a hexaacetato-dlhydroxy-triierric salt and a substance selected from the class consisting of polybasic acids, aliphatic hydroxy acids and the water-soluble salts of the said acids.
• the process for the production of leather which comprises treating hides with a solution of a hexaacetato-dihydroxy-bicarbamido-triferric salt and a substance selected from the class consisting of polybasic acids, aliphatic hydroxy acids and the water-soluble salts of the said acids.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment And Processing Of Natural Fur Or Leather (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=60293657

Family Applications (1)

Country Status (5)

Cited By (1)

• 1937
  • 1937-03-23 DE DE1937I0057506 patent/DE694566C/de not_active Expired
  • 1937-04-06 GB GB9742/37A patent/GB495638A/en not_active Expired
• 1938
  • 1938-03-11 FR FR835115D patent/FR835115A/fr not_active Expired
  • 1938-03-16 BE BE426997D patent/BE426997A/fr unknown
  • 1938-03-19 US US196905A patent/US2178102A/en not_active Expired - Lifetime

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