Reduction system for vat dye or sulfur dyestuff dyeing and reduction method

Abstract

The invention discloses a reduction system for vat dye or sulfur dyestuff dyeing and a reduction method. The reduction system is aqueous solution of thiourea dioxide and weak base, that is, the thiourea dioxide and weak base serve as solute, water serves as solvent, and the weak base is at least one selected from sodium carbonate, trisodium phosphate or sodium silicate; the concentration of the thiourea dioxide is 0.05 mol / L-0.2 mol / L, and the concentration of the weak base is 0.01 mol / L-0.10 mol / L. The reduction method comprises the following steps: adding the dye in the reduction system to prepare dye leuco body solution, heating, dip dyeing textile, and performing after treatment. According to the invention, a selected weak base system is adopted to replace strong base, so that the stability of a reduction leuco body is improved, the dyeing effect is enhanced, the dye-uptake is higher than that of the traditional sodium hydrosulfite-caustic soda method, the color fastness and the color uniformity are better, and the use is safe.

Description

technical field [0001] The invention relates to the field of dyeing and finishing, in particular to a reduction system and a reduction method for vat dye or sulfur dye dyeing. Background technique [0002] Vat dyes and sulfur dyes are important dyes in the process of textile dyeing and printing, but both are insoluble in water. In practical application, printing and dyeing factories need to use reducing agents to reduce the two dyes to water-soluble leuco In order to be dyed in the fiber. [0003] For vat dyes, the commonly used reducing agent is hydrosulfite, which has strong reducibility in caustic soda solution. However, sodium bicarbonate has the following defects in use: [0004] (1) Hydrosulfite will spontaneously ignite, especially after absorbing moisture, it will naturally heat up and burn. The warehouse where hydrosulfite is stored repeatedly burns and causes a fire. [0005] (2) Hydrosulfite releases sulfur dioxide gas during stripping, causing environmental po...

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Problems solved by technology

[0004] (1) Hydrosulfite will spontaneously ignite, especially after absorbing moisture, it will naturally heat up and burn. The warehouse where hydrosulfite is stored repeatedly burns and causes a fire

[0005] (2) Hydrosulfite releases sulfur dioxide gas during stripping, which causes environmental pollution in the workshop and damages the health of workers. Some factories expressly stipulate that they can work in the dyeing workshop for up to three years to avoid occupational diseases.

[0007] (4) The decomposition rate of sodium hydrosulfite in acidic medium is accelerated, and it is not suitable for the stripping of wool and silk fabrics. Especially when stripping wool and silk fabrics, a small amount of soda ash needs to be added to keep the pH value at about 8. Even so, it will still damage Hair and silk, resulting in a decrease in strength

[0008] (5) The storage stability of sodium hydrosulfite is very poor, and it will decompose in the air, resulting in the continuous decline of active ingredients

However, caustic soda is a strong alkali. During the treatment of dyeing and printing wastewater, a large amount of acidic substances need to be consumed. When the pH of the wastewater is adjusted to neutral, the acid consumption is relatively large, which increases the treatment cost, otherwise it will easily cause environmental pollution.

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