A method for chrome-free combined tanning of cowhide

Abstract

The invention discloses a chromium-free combination tannage method for cattle hides. First, pretanning is performed by adopting an organic phosphine salt tanning agent; the central P atoms of the tanning agent have positive charges, so that C atoms near the P atoms have negative charges, and therefore the tanning agent is amphoteric. The functional group hydroxymethyl of the organic phosphine salt tanning agent has very high chemical activity; the finished leather is soft and plump after pretanning; the grain side is smooth; the leather is light in color; the production process is environment-friendly; and crust leather has good retanning, dyeing and oiling performance. In order to further improve the shrinking temperature and use property of the leather, an aluminium tanning agent and a zirconium tanning agent are combined to perform tanning; the shrinking temperature of the leather is enhanced; and the quality of the leather is further improved. Through a reasonable formula and scientific process, the excellent performance of organic phosphine tanning and zirconium-aluminium combination tanning is prominent, so that the performance of the leather can approach or reach the quality of chrome tanned leather.

Description

technical field [0001] The invention belongs to the technical field of tanning technology, and in particular relates to a method for chrome-free combined tanning of cowhide. Background technique [0002] In the tanning industry, due to the superior properties of chrome tanned leather, since Dennis invented the one-bath chrome tanning method in 1893, chrome tanning agent has become the main tanning agent of leather and has dominated. However, there is a shortage of chrome ore resources in my country, and hexavalent chromium has strong carcinogenic and mutagenic effects. The use of chrome salt tanning has caused great harm to the ecological environment, humans and animals, and has posed a great threat to the survival and development of human beings. [0003] After the wastewater produced by the chrome tanning method is treated, a large amount of chromium-containing sludge will be produced. Improper disposal of these chromium-containing sludge will cause secondary pollution to ...

AI Technical Summary

Problems solved by technology

[0007] Organic phosphine tanning method, after pre-tanning with organic phosphine salt tanning agent (tetrahydroxymethylphosphine), the resulting leather is soft, plump, smooth grained, and light in color. The production process is environmentally friendly, but the skin shrinkage temperature is generally 80-85°C , failing to meet the minimum requirement that the shrinkage temperature of leather products is greater than or equal to 90°C

Therefore, it is not possible to use a single organic phosphonium salt tanning agent as the main tanning agent to tan leather

[0008] Aluminum tanning is one of the oldest tanning methods. Aluminum tanned leather has the advantages of pure white, soft, fine grain, bright dyeing, good extensibility, fine hair on the flesh surface, etc. Not enough

[0009] Zirconium tanned leather has the advantages of fullness and firmness, good wear resistance, and the shrinkage temperature can reach above 90°C, etc., but it has high water absorption, hard leather body, and low tear resistance.

[0010] Judging from the current research situation at home and abroad, no single chrome-free tanning agent and tanning method can meet the product quality requirements required by the market so far, and the production practicability is poor.

Although some progress has been made in the research on chrome-free combined tanning, there are still more or less shortcomings, such as low shrinkage temperature, product quality not meeting market requirements, or high production cost, etc., so most of them have no practical value