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How do reactive dyes work
Jul 26, 2018

A reactive dye refers to a soluble dye containing a reactive group. Under appropriate conditions, it can be chemically combined with cellulose fibers and protein fibers to greatly improve the water washing and soaping fastness of the dyed materials. At the same time, it also has the advantages of dyeing, simple printing, bright color, uniform chromatogram and cheaper price. However, generally, the reactive dye has a low fixing rate and is easily hydrolyzed in an alkaline solution to cause floating color. Therefore, the dyeing of the fabric is carried out by first dyeing and then fixing the color to improve the fixing rate of the dye. For printing, depending on the type of dye, one-phase or two-phase printing is used. Some reactive dyes have poor chlorine fastness and weather fastness.

The following points should be noted when using the dye:

1. The selection of the basic three primary colors is important. They should fully consider their solubility, directness, diffusivity, compatibility, sensitivity under normal fluctuations in dyeing conditions, fixation action and washability to ensure dyes. The balance between directness and diffusivity can be quickly achieved, and the directness, diffusivity, fixation behavior and washability of the dye are reasonably balanced.

2, especially in light color when dyeing light color, because the azo-type red dye and azo-type blue dye have poor light fastness, can not meet the market demand, need careful choice. As for the use of the light fastness improver, it is necessary to pass the experiment, generally speaking, the method of using the ultraviolet absorber to improve the light fastness of the reactive dye is not obvious.

3, when dyeing deep dark color, many varieties have poor wet rubbing fastness, can not meet the market requirements, and need to be used with caution. The key to improving the wet rubbing fastness of reactive dyes lies in the basic dyeability of cotton materials, that is, the surface texture, surface texture, smoothness, and hardness of cotton fibers. They are related to the quality of raw cotton and cotton yarns and the pretreatment of cotton fibers. Directly related.

4. For the requirements of the composite fastness of textiles proposed in the market, such as sweat light fastness, fading fastness of alkaline wet sunlight, fading fastness of alkaline wet sunlight containing peroxide, etc., such reactive dyes still exist. Certain problems need to be selected through experiments, which are also the focus of research and development of heterogeneous double reactive dyes today.

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