Treatment process for reducing content of hexavalence chromate in leather

A treatment method, the technology of hexavalent chromium, applied in the field of tanning, can solve the problems of few fatliquor additives, long-distance practical application, slow alkali-lifting speed, etc., and achieve simple process and operation, wide application range and low treatment cost Effect

Inactive Publication Date: 2006-05-17
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the different types of tannins, the effects vary greatly, so it is not universally applicable to different types of leather.
②In the fatliquoring process, add fatliquor additives with anti-oxidation function (Sun Genxing, Yu Congzheng. Research progress of hexavalent chromium in leather [J]. China Leather, 2002, 31(7): 35~39). Prevent the production of hexavalent chromium, but its cost is high, and there are few fatliquor additives available
③ Control the content of hexavalent chromium in the finished leather by adjusting the tanning process, for example, use alkali-raising materials mainly composed of calcium oxide and magnesium oxide with a slow alkali-raising speed, use cationic materials, and reduce the drying temperature, etc. ( Yuan Ximing. Control of Cr(VI) content in finished leather[J]. China Leather, 2003, 32(15): 29~30), this method is cumbersome, difficult to control, and the effect is uncertain
Although this method can completely eliminate hexavalent chromium in leather, due to the immature technical conditions, the performance of the finished leather cannot fully meet people's requirements, and it is still far from practical application.

Method used

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  • Treatment process for reducing content of hexavalence chromate in leather

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] First take sodium thiosulfate and prepare it into an aqueous solution with a mass percentage concentration of 0.5%, then evenly spray the configured sodium thiosulfate solution on a batch (100 sheets) of 15 mg / kg hexavalent chromium with a spray gun. Spray 3 times on the meat surface of the finished brown cowhide shoe upper leather, and finally stack the leather flesh surface sprayed with an aqueous solution of sodium thiosulfate reducing agent on the flesh surface in a normal temperature sheltered environment with a relative humidity of 55-60%. After standing for 2 days, it can be processed according to the subsequent conventional process conditions. No hexavalent chromium was detected in the finished leather.

Embodiment 2

[0029] First take ferrous sulfate and prepare it into an aqueous solution with a mass percent concentration of 1.0%, and then evenly spray the configured ferrous sulfate aqueous solution on a batch (100 pieces) of light coffee with a hexavalent chromium content of 20 mg / kg with a spray gun. Spray 2 times on the meat surface of pigskin clothing leather products, and finally pile up the leather meat surface sprayed with the ferrous sulfate reducing agent aqueous solution in a normal temperature sheltered environment with a relative humidity of 50-55%, and place it in shelter for 5 Days later, it can be processed according to the follow-up conventional process conditions. No hexavalent chromium was detected in the finished leather.

Embodiment 3

[0031] First, weigh sodium sulfite and ammonium ferrous sulfate according to the mass ratio of 2:1, and prepare it into a mixed aqueous solution with a mass percentage concentration of 2.5%, and then spray the mixed aqueous solution of sodium sulfite and ammonium ferrous sulfate evenly on a batch of (100 pieces) The meat surface of the finished black goatskin garment leather with a hexavalent chromium content of 30 mg / kg is sprayed twice, and finally the flesh surface of the leather sprayed with sodium sulfite and ammonium ferrous sulfate reducing agent aqueous solution is stacked on the flesh surface. In a sheltered environment at normal temperature with a relative humidity of 55-65%, place it sheltered from the wind for 7 days, and then treat it according to the follow-up conventional process conditions. The content of hexavalent chromium in the finished leather was detected to be 0.21 mg / kg.

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Abstract

The treatment method for reducing the content of hexavalent chromium in leather provided by the present invention is characterized in that the aqueous solution of reducing agent with a mass percentage concentration of 0.5-3.0% is sprayed on finished leather and semi-finished leather after wet operation, or the same concentration The aqueous solution of reducing agent is used to treat the semi-finished leather after wet operation in the drum. The reducing agent used is at least one of ferrous sulfate, ferrous chloride, ammonium ferrous sulfate, sodium sulfite, potassium sulfite and sodium thiosulfate. The invention can be used not only for the treatment of finished leather whose hexavalent chromium content exceeds the standard, but also for the treatment of semi-finished leather in the process of tanning, so as to prevent the generation of hexavalent chromium in the finished leather. The process and operation of the present invention are simple, the source of the reducing agent is abundant, the price is low, the treatment cost is low, the process after tanning and the quality of the leather are not affected, and the content of the treated leather or hexavalent chromium is below 3mg / kg, or the detection is not good. out.

Description

1. Technical field [0001] The invention belongs to the technical field of leather making, and in particular relates to a treatment method for reducing the content of hexavalent chromium in leather. 2. Background technology [0002] Chromium often exists in two valence forms of positive trivalent and positive hexavalent, and the different valence states have different impacts on the environment and biological effects. It is believed that trivalent chromium is a trace metal element necessary for organisms and the human body, while hexavalent chromium is a strong carcinogenic and mutagenic inducing factor, and its toxicity is 100 times greater than that of trivalent chromium, which can affect the cells. Oxidation, reduction, can combine with nucleic acid, have stimulating, carcinogenic, and mutagenic effects on the respiratory tract and digestive tract, and hexavalent chromium has a strong damage effect on the skin. Even a small dose of hexavalent chromium on the exposed parts ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C14C3/30
Inventor 陈武勇辜海彬王应红尹洪雷
Owner SICHUAN UNIV
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