METHOD FOR ANIMAL SKIN TANNING WITH DIALDEHYDES Russian patent published in 2021 - IPC C14C3/16 C14C3/28 

FIELD: leather industry.

SUBSTANCE: invention relates to the leather industry, in particular to the leather tanning. A method for animal skin tanning includes stages of: (a) bringing the animal skin into contact with the first tanning solution containing at least one dialdehyde according to the general formula (I) O=CH-(CH₂)_n-HC=O (I), where n is 0 or an integer in the range from 1 to 8, and a pH value of the tanning solution is in the range from 1 to 5; (b) bringing the pH value of the tanning solution to a value greater than 5 and less than 8; (c) repetition one or more times of stages (a) and (b) of exposure to the skin coming from the stage (b) using the second or subsequent tanning solution; where the first, the second and the subsequent tanning solutions are essentially free of surfactants and where the method is free from tanning processing using chrome tanning agents. Dialdehyde, according to the general formula (I), is selected from: glyoxal, malonic dialdehyde, succinic dialdehyde, glutardialdehyde, adipine dialdehyde, pimelin dialdehyde and mixtures thereof. Dialdehyde is present in the first and the subsequent tanning solutions in the amount ranging from 0.1 to 30.0 wt.% relatively to the weight of the raw hide, preferably in the range from 0.5 to 15.0 wt.%.

EFFECT: proposed method for animal skin tanning provides the possibility of reducing the number of visible surface defects on the finished tanned leather, the possibility of obtaining tanned leather of large thickness and with a high yield in area.

10 cl, 3 dwg, 3 ex