For ages, dyes have brought life to mankind. It gives different media (textile, paper, food, even your hair) both subtle and ingenious, as well as apparent and suggestive changes to our everyday interaction as it is incorporated in most of the things that we see around us. It invigorates a what-would-be a dry and dreary world. It also enhances what may already be considered as totally appealing, and creates a myriad of meanings as well as uses, depending on the color it grants to the material as well as the substance it is combined with.
Dyes are usually applied in an aqueous solution, and may also require a mordant to improve its hold or fastness on the fiber it is incorporated into.
Moreover, dyes can either be natural or synthetic. Majority of natural dyes are extracted from plants and trees, including the roots, berries, bark, leaves, and wood, as well as from other living things that cling on to these plants and trees, such as fungi and lichens. Textile dyeing can be traced back to the Neolithic ages. People have dyed textiles using familiar as well as locally available materials. There are also valuable yet scarce dyestuffs that can produce vivid as well as permanent colors such as the natural invertebrate dyes Tyrian purple and crimson kermes that were used during the ancient and medieval world. Plant-based dyes like indigo, saffron and madder were cultivated commercially and were important trade goods in Asia and Europe. Across Asia and Africa, patterned fabrics were produced using resist dyeing techniques that control the absorption of color in piece-dyed cloth.
Throughout time, dyes have been and are still being used to allow mankind to have a greater satisfaction of everything that is available within him. To make the use of these colorants even more exciting and easily available to more people, man made use of synthetic dyes. By the 19th century, man-made synthetic dyes has the ended the large-scale market for natural dyes.
Synthetic dyes are made from synthetic resources such as petroleum by-products and earth minerals. Records show that the very first human-made organic aniline dye, mauveine, was accidentally discovered in 1856 by William Henry Perkin, during a failed attempt at the total synthesis of quinine. Creation of fuchsine, safranine, and induline, as well as other aniline dyes followed.
Textile dyes dates back as far as the Bronze Age. In the 21st-century Textile dyes constitutes an important segment of the whole business of specialty chemicals. Dyes that are used today in the textile industry are predominantly synthetic, and mostly come from two sources namely, coal tar and petroleum-based intermediates. These dyes are sold as powders, granules, pastes or liquid dispersions. The concentrations of active ingredients in these dyes generally ranges from 20 to 80 percent. The textile dye section is marked by new dyes. New dyes are constantly created to meet the demands of current technology, new kinds of fabrics introduced, cleansing agents, advances in dyeing machineries, along with overcoming the serious environmental concerns presented by some existing dyes. Another vital consideration in the introduction of new dyes is the fact that almost all the products are subjected to seasonal demand as well as variants. Industrial textiles dyes need to sustain all these new and specific technical requirements.
Together with the quick changing product profile of the textile industry– from high-cost cotton textiles to the durable as well as versatile synthetic fibres, pattern of consumption of these dyes also goes through prompt changes. Today, Polyesters contributes to a major part of dye consumption. Consequently, disperse dyes used in Polyesters, are also calculated to grow at a faster rate.
Types of Textile Dyes
Dyes are classified according to their solubility as well as their chemical properties. Though commercial textile dyes are categorized by their generic name and chemical constitution, which is done by the Color Index (C.I.), a journal published by the Society of Dyers and Colourists (United Kingdom) in association with the American Association of Textile Chemists and Colorists (AATC), if general dye chemistry is considered as one of the basis for classification, textile dyestuffs can be grouped as follows:
Acid dyes are water-soluble an-ionic dye type that is usually applied to fibers like wool, nylon, silk, and modified acrylic fibers using neutral to acid dye baths.
Basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers. There are some that are used for wool as well as silk. Basic dyes are also incorporated in the production of colored paper.
Direct or substantive dyes, on the other hand, are used on cotton, paper, leather, wool, silk and nylon.
Vat dyes are insoluble in water and incapable of dyeing fibers directly. For instance, the indigo colour in denims is due to the original vat dye property in it.
Reactive dyes utilize the covalent bonds and attaches it to natural fibers to make them among the most permanent of dyes. These type of dyes are by far the best choice for dyeing cotton and other cellulose fibers at home or in the art studio.
Disperse dyes were initially utilized in dyeing cellulose acetate. These dyes are water-insoluble. Their main function is to dye polyester, but they can also be used to dye nylon, cellulose triacetate, as well as acrylic fibers.
Azoic dyes are created by treating a fiber with both diazoic and coupling components. With suitable adjustment of dye-bath conditions, the two components react to produce the required insoluble azo dye. However, as creating azoic dyes incorporates toxic chemicals, the use of these type of dyes is decreasing.
Sulfur dyes are low-cost dyes used to dye cotton with dark colors.
All these dye types can be grouped together into three categories namely:
- Dyes for Cellulose Fibers
- Dyes for Protein Fibers
- Dyes for Synthetic Fibers
Dyeing is a very crucial process. In a competitive market that we have, reliable, cost-effective products as well as the latest technological solutions are vital for businesses to survive. A number of factors are considered in making the dyeing process the right one for one not only save capital but also take care of the environmental problems associated with dyeing.