The polyester fibers used in the textile sector are very clean. Disperse dyestuffs are generally used to dye the polyester. The disperse dyeing process uses disperse dye particles mechanically milled below 1 micron. These materials are molecularly soluble at high temperature, water and are absorbed at the same temperature by the fluidic region of the polyester. The dyestuff first adheres to the surface of the polyester, then slowly penetrates into the polyester.

Disperse dyes are low molecular weight compounds with amino and hydroxyl groups. During dyeing, the fibers are bonded between the amino and hydroxyl groups in the dyestuff. Polyester fiber has the property of escaping from water and large molecule dyestuffs cannot easily enter into the fiber. For this reason, the most commonly used dyes in polyester dyeing are disperse dyes.

Disperse dyes were called acetate dyes because they were first dyed acetate fibers. It is now referred to as disperse dyes since it is now applied to all synthetic products.

Disperse dyes, like all dyes, are ultimately a chemical and some species show carcinogenic effects. In this respect, textile products should also be tested for disperse dye properties.

Among the chemical and ecological tests carried out in the laboratories accredited within the scope of TS EN ISO / IEC 17025 standard from domestic or foreign accreditation organizations, tests are carried out to determine the amount of carcinogenic disperse dyes in textile products. These studies are based on the following standards:

• DIN 54231 Textiles - Determination of disperse paint coatings
• TS EN ISO 105-Z04 Textiles - Color fastness tests - Part Z04 - Dispersibility of disperse dyes

Laboratories have to have a state-of-the-art infrastructure and a trained and experienced staff in order to get high quality, fast and reliable results.