1. Definition and properties

Dyes are colored compounds possessing a chromophore moiety and chemical groups enabling them to interact either with the fiber ("reactive" groups) or with their solvent medium (solubilizing or dispersing groups). Dyes are therefore either soluble or dispersible in a liquid (usually water). They can be attached to a fibrous material by various types of bond (covalent, ionic, hydrogen or Van der Waals) or simply by mass incorporation into the thermoplastic material (colored pigments incorporated into the polymer structure during manufacture). The term "colorant" is used to describe two different types of substance:

• The dye molecule is made up of an auxochrome part and a chromophore part. It is a colored compound that must have an affinity for the fiber and/or filament to be dyed (physico-chemical "attraction" of the dye to the substrate).

  ...