Different Types of Dyestuffs in Relation to the Fiber Substrate
Sunman Textile Mills Ltd. Chittagong
The desire to color textiles is an old as spinning and weaving. Natural coloring materials have been used for thousands of years; mineral pigments such as yellow and red ochre, cinnabar; vegetable dyes such as indigo, litmus, logwood, madder, saffron; animal dyes such as cochineal, Tyrian purple. Synthetic dyes were first produced in the 19 century and have now almost completely replaced the natural colors. Environmental and product safety aspects are currently very important.
With the exception of pigment/binder systems the types of dyestuffs has to be chosen to suit the fiber substrate, because the formation of a physical or chemical bond between dye and fiber depends on the chemical and physical structures of both dye and fiber. A broad spectrum of colors is available in countless shades and a wide range of fastness for the different fiber types and blends.
Different Types of Dyestuffs in Relation to the Fiber Substrate:
1. Reactive Dye: Applicable for cotton, linen, viscose, wool, silk. The dyestuff forms a chemical Iink with the fibre. It has very good fastness properties.
2. Disperse Dye: Applicable for polyester, nylon, acetate. It is water in soluble; applied’ from dispersions; diffuse into the fiber at high temperature. It has also good fastness properties.
3. Vat Dye: Applicable for cotton, linen, viscose. The insoluble dyestuff is made soluble in a reducing vat so that it can diffuse into the fiber. After diffusion is complete, it is then re-oxidised into its in soluble form. It has high fastness to washing, chlorine, boiling, light, weather, rubbing and perspiration.
4. Direct Dye: Applicable for cotton, linen, viscose, silk. Simple diffusion into the fiber, from aqueous solution. It has relatively poor fastness properties to light, washing and perspiration. These fastness properties can be improved by after treatment.
5. Basic Dye: It is suitable for acrylic fibers (other fibers by mordanting). It reacts with acidic groups, or mordants (a chemical which can react or complex with a chromophore to form an insoluble colour) in the fiber. It has good fastness properties on acrylic fibers.
6. Acid Dye: Applicable for wool, silk, nylon. Applied from an acidic dyebath. The fastness properties of this dye-stuff depends on the fibre type.
There are also some other types of dyestuffs such as sulphur, azoic, metal complex, chrome dyes etc.
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