How to improve wet rubbing fastness？

1. Choose reactive dyes with high lifting power

The concentration of dyes used in deep dyeing is high, and the amount of floating dyes increases. The fiber has a saturation value for dye adsorption, and the dye concentration should generally not exceed 10% of the dyeing saturation value. Excessive dye cannot be dyed and fixed, and will accumulate on the surface of the fabric, thereby affecting the wet rubbing fastness of the dyed product.

2. Reasonable dyeing and finishing process

In addition to the correct selection of dyes, reasonable dyeing and finishing processes can also improve wet rubbing fastness. The smoother the fabric surface, the higher the wet rubbing fastness, so the singeing should be clean, and the colored fiber particles should be reduced. The hair effect of the dyed semi-finished products directly affects the dye penetration of the dye. The better the penetration, the better the diffusion of the dye into the fiber after dyeing, which is beneficial to reduce the accumulation of dye on the surface of the fabric. The addition of penetrant and mercerizing treatment are beneficial to improve the wet rubbing fastness.

The degree of washing off floating dyes is related to their directness to fibers. The most direct vinyl sulfone dyes are the most difficult to remove, followed by hydrolyzed dyes.

The unreacted β-sulfate vinyl sulfone dye has the least directness due to the presence of sulfate water-soluble groups and is the easiest floating dye to remove. Washing and soaping can remove floating color, electrolytes and alkalis. The auxiliaries used in soaping must have good penetrating ability, easy to be compatible with dyes, and form micelles, reduce the affinity of dyes and fibers, and form the inner core so that the dye micelles can be stably dispersed in water. Anionic and non-ionic surfactants with penetrating and dispersing functions can be used as additives, otherwise the effect of thoroughly washing off the floating color will not be achieved.

3. Water quality is a very important factor. If the water quality is high in hardness, the water-soluble groups of floating dyes will form lakes that are difficult to dissolve in water, which will seriously affect the removal of floating dyes. The drying method is also very important. The amount of dye molecules transferred by contact drying is higher than that of non-contact drying.

4. Control of pH value on the surface of dyed fabric

In the process of dyeing deep and dense fabrics with reactive dyes, the amount of alkali is relatively high and washing must be strengthened. The pH value of the dyed fabric surface should be controlled at 6.5-7.5 (Oeko-Tex standard 100 technical standards are pH 4.0-7.5 and 4.0-9.0) to prevent the ether bond between the vinyl sulfone group and the fiber from being broken by the alkaline medium. fade.