When dyeing cellulose fibers with reactive dyes, the dyeing mechanism is different from other dyes. As a result of dyeing, the dyes on the fibers are not physically dyed on the fibers by hydrogen bonds, ionic bonds or van der Waals forces, but in the form of covalent bonds. Chemically combined with the fiber, the dye molecules become part of the cellulose macromolecular bond after dyeing. Therefore, in theory, the covalent bond between the dye and the fiber can endow the dyed product with excellent dyeing fastness. However, in actual production, fading, discoloration or staining often occur in the dyed products during testing, washing and even storage. Especially the wet rubbing fastness when dyeing deep colors (such as black, navy blue, coffee, soap red, etc.), usually only has a second grade, and often does not reach grade 2-3 or grade 3.

Causes of poor wet rubbing fastness

How to improve the wet rubbing fastness of dyed products to meet the needs of the market?

The so-called wet rubbing fastness of dyed cloth refers to the use of wet white cloth to rub against the dyed cloth under specified conditions, and then according to the degree of staining of the white cloth, it is graded with a standard gray staining sample card.

Obviously, there are two reasons for poor wet rubbing fastness:

1. The floating dye on the surface of the fabric (or fiber), during the rubbing process, the white dyed cloth is transferred to the wet white cloth.

2. The fine particles of colored fibers on the surface of the dyed cloth are transferred from the white dyed cloth to the wet white cloth during the rubbing process.

It can be seen that the amount of floating dye on the surface of the fabric (or fiber) and the amount of colored fiber chips are the decisive factors that determine the wet rubbing fastness. There are many factors that affect the amount of floating color dye and the amount of colored fiber fiber chips. It is not only related to the performance of the dye, but also related to the dyeing and finishing process.