The present invention belongs to the technical field of
leather tanning, and discloses a salt-free and
chromium-free tanning method. The method uses softened bare
skin as
raw material, and realizes an
environmentally friendly and efficient tanning process by sequentially carrying out bio-based dialdehyde
carboxylic acid pre-tanning, salt-free
pickling and iron salt tanning. Among them, the amount of bio-based dialdehyde
carboxylic acid added is 1wt%-5wt% of the weight of the bare
skin, and the amount of iron salt added is 5wt%-30wt%. The dialdehyde group in the bio-based dialdehyde
carboxylic acid can pre-tan and soften the bare
skin, block the amino group and cross-link collagen, effectively prevent acid swelling, and realize salt-free
pickling; its carboxyl group provides an additional
binding site for the iron tanning agent, forming a strong cross-linking network and enhancing the tanning performance. In addition, the bio-based dialdehyde carboxylic acid can also scavenge free radicals and fix Fe 3+ , to avoid deterioration and deterioration of leather during storage. The present invention is not only
environmentally friendly and has excellent tanning properties, but also has good storage stability for tanned leather, providing strong
technical support for the clean transformation of the
leather industry.