There are many kinds of acid dyes with complete chromatography and bright color. Their molecules contain sulfonic acid group (- SO3H). They are water-soluble anionic dyes. In weak acid, strong acid or neutral bath, they can form hydrogen bond with amide group on silk and wool fiber molecules, and can also form ionic bond with amine group and imine group on nylon fiber Therefore, acid dyes are widely used in the dyeing and printing of silk, wool, nylon and other fabrics. According to the dyeing properties, they can be divided into strong acid, weak acid and neutral dyes.
Strong acid dyes have low molecular weight and low affinity with fibers, The directness is also small. During dyeing, it is easy to diffuse and transfer in the fiber, so it has good levelness, but it only depends on the combination of ionic bond and fiber, so the color fastness is not ideal. The molecular weight of weak acid dyes is large and has great affinity with the fiber. Although it is difficult to diffuse and transfer during dyeing, the levelness is general, but good levelness can still be achieved by adding additives during dyeing. It has not only ionic bond but also hydrogen bond and van der Waals gravitational bond with the fiber, so it has strong color fastness Good dyeability, dark color is a common acid dye.
Acid dyes must also be washed after dyeing to remove various auxiliaries and dyes that do not react with the fiber to achieve a certain color fastness, because weak acid dyes have a relatively large affinity for the fiber. During washing, the dyes in the washing solution are easy to stick back to the fiber and affect the color fastness, such as acid red f3gl, acid red 10B, Acid Blue 6B, acid brilliant blue G, acid lake blue 5gma, acid black B Acid black BGL and other dyes are easy to stain, especially red and blue series dyes, which are difficult to repair after staining, so anti staining soap must be used when washing.
Because the anti-stainning performance of acid dyes is completely different from that of reactive dyes, the antifouling soaping agent composed of acid dyes is also completely different. Acid dyes are strong anionic dyes. The antifouling effect can be achieved only by using the strong adsorption effect of cationic surfactants and compounding high-efficiency dispersants.
