Reactive Dyes

Reactive dyes are dyes that form a chemical bond with the fibers of the textile material during the dyeing process. This chemical bond forms a permanent attachment in the fibers, which cannot be removed by repeated treatment with boiling water under neutral conditions. As a result, the dyes become part of the fiber, leading to excellent wash color fastness.

Reactive dyes have a wide range of colors and are mainly used for dyeing cellulosic fibers such as cotton and flax. In reactive dyeing, the dye molecules diffuse into the fibers and establish a chemical bond with the fibers upon fixation. Although pigments are the most commonly used colorants in textile printing, reactive dyes are the most commonly used of all other dyes, accounting for 30% of the total colorants used in the printing industry.

As a professional supplier of high-efficiency dyes, Alfa Chemistry has the ability to provide customers with a comprehensive range of reactive dyes including:

• Reactive Cold Dyes
• Reactive HE Dyes
• Reactive Hot Dyes
• Reactive ME Dyes
• Reactive Vinyl Sulphone Base Dyes
• Reactive Printing Dyes
• Other Reactive Printing Dyes

Structure of Reactive Dyes

Typically, reactive dyes consist of four components (figure 1) ^[1]:

• Dye part or chromogen (color producing part), which contributes color to the dye.
• Bridging part that joins the reactive system to the chromophoric part.
• The solubilizing group(s) attached to the chromophoric grouping confers water solubility to the dye.
• Reactive group which enables the dye to react with the substrate. This part can also react with water molecules present in the dyebath; a phenomenon called hydrolysis of the reactive dyes which is not a desirable reaction during dyeing.

Fig. 1 Schematic structure of reactive dyes

Reactive Dyeing Process

Common Auxiliaries in Reactive Dyeing

The wide range of available reactive dyes allows a large number of dyeing techniques to be used. In dyeing cellulose fibers with reactive dyes, the following auxiliaries are used:
- Alkalis (sodium carbonate, bicarbonate and caustic soda).
- Salt (mainly sodium chloride and sulfates).
- Urea can be added to the filling solution in the continuous process.
- Sodium silicate can be added in the cold pad batch method.

Alfa Chemistry is committed to becoming a first-class, low-carbon, environmentally friendly dye supplier. Our mission is to provide customers with full specifications of high-quality dyes. We are also constantly expanding our product database to meet the wide range of customer needs. You are welcomed to contact us for more reactive dyes.

It is important to note that our products are for research use only and are not for clinical use.