Bleaching and dyeing; fluid treatment and chemical modification – Treatment of hides – skins – feathers and animal tissues – Tanning
Patent
1975-04-29
1977-08-16
Michl, Paul R.
Bleaching and dyeing; fluid treatment and chemical modification
Treatment of hides, skins, feathers and animal tissues
Tanning
8 9427, C14C 306
Patent
active
040423212
ABSTRACT:
In the chrome-tanning of hides to produce leather wherein a hide is pickled, pretanned with a chromium (III) salt, and full tanned with a tanning mixture containing a chromium (III) salt, an acid-binding agent and a polycarboxylic acid or salt thereof, the improvement which comprises employing as said polycarboxylic acid or salt thereof at least 1.6 moles per mole of Cr.sub.2 O.sub.3 in the chromium (III) salt employed for full tanning of an aliphatic dicarboxylic acid of 4 to 6 carbon atoms or an aromatic dicarboxylic or tricarboxylic acid containing 8 to 13 carbon atoms or a salt thereof, the total quantity of Cr.sub.2 O.sub.3 employed in pretanning and full tanning ranging from 1.2 to 2% by weight of the hide, full tanning being carried out with up to 100% of the tanning liquor based on the weight of the hide to a final pH of the liquor of at least 3.6. Advantageously, a powder composition comprising additional chromium (III) salt, polycarboxylic acid or salt and acid-binding agent, preferably dolomite, is added after pretanning.
REFERENCES:
patent: 2091683 (1937-08-01), Immendoerfer
patent: 2178874 (1939-11-01), Hervey
patent: 2580417 (1952-01-01), Follett
patent: 3010780 (1961-11-01), Plapper
patent: 3346323 (1967-10-01), Spahrakas
Zissel, Das Leder, Jan. 23, 1972, pp. 174-183.
Backer Klaus
Heinze Helga
Luck Wolfhard
Spahrkas Heinrich
Bayer Aktiengesellschaft
Michl Paul R.
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