Views: 11 Author: Site Editor Publish Time: 2021-05-14 Origin: Site Inquire
The dyeing mechanism of reactive dyes on cellulose fibers 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. It is chemically combined with the fiber, and the dye molecules become part of the cellulose macromolecular bond after dyeing. Therefore, theoretically, the covalent bond between the dye and the fiber can give the dyed fabric excellent dye fastness. However, in actual production, the dyed products will often fade, change or stain during testing, washing, and even storage. In particular, the wet rubbing fastness when dyeing deep and thick colors (such as black, navy blue, coffee, soap, etc.) is usually only two, often not reaching 2-3 or 3.
Causes of poor wet rub fastness
How to improve the wet rubbing fastness of dyed products to meet market demand?
The so-called wet rubbing fastness of dyed cloth refers to rubbing a wet white cloth with the dyed cloth under specified conditions, and then according to the degree of staining of the white cloth, it is rated with a standard gray staining sample card.
Obviously, there are two reasons for the poor wet rubbing fastness:
1. The floating dye on the surface of the fabric (or fiber) transfers the white dyed cloth to the wet white cloth during the rubbing process.
2. The micro-swarf of colored fibers on the surface of the dyed cloth transfers 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 microchips are the decisive factors that determine the wet rubbing fastness. There are many factors that affect the amount of floating dye and the amount of colored fiber flakes. It is related to the performance of the dye and also related to the dyeing and finishing process.
To improve the wet rubbing fastness of reactive dyes, it is necessary to study from many aspects such as dye selection and process formulation, and implement corresponding technical measures in a targeted manner.