Direct dye application classification

Direct dye application classification

1) Direct dyes with level dyeing properties:

the molecular structure of dyes is simpler, tends to gather less, has lower affinity, higher diffusion rate, good level dyeing, and the dye-promoting effect of salt is not significant, the dyeing is easy to reach equilibrium, and the dyeing temperature rises. High will reduce the equilibrium dye uptake rate, so the dyeing temperature should not be too high, usually at 70~80°C. The wet treatment fastness of this kind of dyes is low, generally only suitable for dyeing light colors.

 2) Direct dyes with salt effect: 

The molecular structure of dyes is relatively complex, and the molecules contain multiple water-soluble groups, which have high affinity for fibers, low diffusion rate of dyes in fibers, poor levelling properties, and neutral salt. The electrolyte has a significant effect on promoting dyes of this type. 

3) Temperature effect direct dyes: 

The dye has a complex molecular structure, high affinity to fibers, low diffusion rate, and poor level dyeing. The dye molecule contains fewer sulfonic acid groups, and the salt effect is not obvious. The dye uptake percentage generally increases with the increase of dyeing temperature.

 4) Direct blending dyes: 

Direct blending dyes are also called direct D-type dyes. These dyes have higher dye uptake to cellulose fibers, wet processing fastness, color vividness, and compatibility with other dyes than conventional direct dyes. The dye is good. It has good compatibility with disperse dyes and is suitable for one-bath-step dyeing of polyester-cotton blended fabrics with disperse dyes.

 5) Direct cross-linking dyes: 

The molecular structure of dyes contains reactive groups such as amino, hydroxyl, and substituted amino groups. Cross-linking can be formed between the dye and the fiber by using a matching reactive cationic fixing agent. This type of dye has uniform color, good dyeing reproducibility, high wet treatment fastness, and has the effect of resin finishing, and has low formaldehyde content.