Method for solving exceeding standard problem of hexavalent chromium from natural leather

Abstract

The invention relates to the technical field of leather making chemistry and engineering, and provides a method for solving exceeding standard problem of hexavalent chromium from natural leather. The method comprises a pre-humidification treatment technology, a dry state roller coating / spraying technology, and a fumigation processing technology, these technologies can greatly reduce hexavalent chromium content with exceeding standard from the natural leather from 8.60mg / kg to 1.37mg / kg, which can accord with a hexavalent chromium content standard (3mg / kg) in natural leather and its product on international market, the above three technologies are employed for processing natural leather with exceeding standard hexavalent chromium, physical mechanical property, chemical performance and sensory property of the processed natural leather are not changed, and each index accords with an industry standard.

Description

technical field [0001] The invention relates to the technical fields of tanning chemistry and engineering, in particular to a method for solving the problem of excessive hexavalent chromium in natural leather. Background technique [0002] In the 21st century, with the improvement of people's living standards, leather products have become a part of people's daily life. In 2012 alone, my country's tanning industry completed a total industrial output value of 1,055.6 billion yuan, and its export volume reached 76.09 billion US dollars. The total profit was 68.052 billion yuan, my country has become a world recognized leather production and trade power. [0003] In the tanning industry, tanning is the most widely used method at present. Chrome tanning agents have excellent tanning performance, simple operation and low cost. More than 80% of the world's leather is chrome tanned. The use of incompletely reduced chromium powder and the use of hexavalent chromium materials such as ...

AI Technical Summary

Problems solved by technology

[0005] At present, the methods for practitioners to reduce the content of hexavalent chromium in leather include: 1. Adding fatliquoring additives with anti-oxidation function in the fatliquoring process (Sun Genxing, Yu Congzheng. Research progress of hexavalent chromium in leather[J]. China Leather, 2002, 31 (7): 35-39), although it can prevent the transformation of trivalent chromium to hexavalent chromium, its cost is relatively high, and there are few fatliquor additives available for this type; 2. In the process of leather production, reducing agent is used to eliminate hexavalent chromium in leather (as disclosed in the Chinese patent application number CN200410040490.4, titled "treatment method for reducing hexavalent chromium content in leather"), however, During the production, it was found that the chrome-tanned leather treated with reducing agent could not detect hexavalent chromium. During the storage process, hexavalent chromium was gradually produced within a few months, and the content of hexavalent chromium in the belly of the leather was generally higher than that in the back. Explain that although hexavalent chromium in leather can be eliminated by using a reducing agent, this treatment method cannot prevent the oxidation of trivalent chromium into hexavalent chromium in the long service life of leather and leather products; 3. The Chinese patent application number is CN200910058827.7, titled "Method for Stabilizing Trivalent Chromium in Leather and Minimizing Hexavalent Chromium Content", discloses that the respectively prepared reducing agent and protective agent aqueous solution are sprayed on the surface of the finished leather flesh, and stacked at room temperature and constant humidity. At least 3 days in a sheltered environment, or submerge the semi-finished leather after wet treatment or the finished leather after rewetting treatment in the prepared reducing agent aqueous solution for at least 15 minutes, and then submerge in the protective agent aqueous solution for at least 15 minutes After the treatment, the semi-finished leather can be treated in the conventional follow-up process. Although hexavalent chromium cannot be detected in the leather treated by this treatment method, the aqueous solution of the reducing agent and the protective agent is easily adsorbed on the surface of the leather or leather products. Inhomogeneous distribution in the interior, which easily leads to insufficient reduction of hexavalent chromium in leather or leather products

[0006] In summary, in order to reduce or eliminate the harm of hexavalent chromium to the environment and human body, and to solve the problem of excessive chromium hexavalent content in natural leather and its products, most of the research by practitioners has focused on adding hexavalent chromium treatment agents in the leather manufacturing process. To reduce the hexavalent chromium content in finished leather, or add hexavalent chromium treatment agent, to reduce the ratio of trivalent chromium to hexavalent chromium, reduce the conversion rate of hexavalent chromium in the process of using natural leather and its products; but for the solution The research on the problem of hexavalent chromium exceeding the standard in natural leather and its products is still incomplete, and most of them focus on the backwater treatment method. On the one hand, this method has high treatment costs; Not suitable for finished leather that has been finished

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