What are chlorine fastness and sweat-light fastness?

Reactive dyes generally have poor chlorine fastness, which mainly depends on the molecular structure of the color body. There are sulfonic or carboxylic acid groups at the ortho position of the diazo group of the dye, or there are sulfonates at the ortho or para position of the hydroxyl group of the coupling component. In the case of acid groups or carboxylic acid groups, due to its steric hindrance, the ability of CI- to attack -NH- or -N- is reduced, thereby improving the chlorine fastness.

According to the GB/T8433-1998 test method for water fastness to chlorine-containing swimming pools, the available chlorine concentration is divided into three types: 20mg/L, 50mg/L and 100mg/L, with 200mg/L for special requirements. As the concentration of available chlorine increases, the chlorine fastness decreases. Therefore, the choice of dye is very important, and the method of fixing agent can also be used in the finishing process to improve the chlorine fastness, but it can only be improved by 0.5-1.0 level. The perspiration-light fastness of reactive dyes has received great attention in recent years. Some reactive dyes have good light fastness but poor perspiration light fastness. Because under the dual action of sweat and sunlight, the fading mechanism is different. The amino acid or related substances in sweat chelate with the metal ion of the metal complex dye to separate it from the dye matrix. The light fastness of the dye matrix before complexation is originally Not good, so it fades or discolors.