Leather tanning with oligourethanes

摘要

This invention is concerned with a method of tanning or retanning leather or pelts by treating them with an aqueous liquor containing water-soluble oligourethanes having ionic groups. The oligourethanes have a molecular weight of from 300 to 20,000 and they may be methylolated. The oligourethanes may be water-soluble owing to their ionic groups or they may contain hydrophilic segments to aid in their solubility in the aqueous liquor. The liquor may also contain up to an equal amount of formaldehyde or compounds which split off formaldehyde.