Sardar Chemical produce complete range of Direct Dyes & for there are certain products we are the only manufacturer in Pakistan. The direct dyes offered by Sardar Chemicals are suitable for dyeing cotton and viscose in the form of fabric, yarn, loose cotton. These dyes are available in complete range and are Azo free. Our range is provide in proper and durable packing to make sure that these reach our clients safely and can be stored to maintain its shelf life.
Direct dyes are designed for the primary purpose of dyeing of cotton and cellulose and are suitable for dyeing cotton and viscose in the form of fabric, yarn, loose cotton. These dyes are available in complete range and are Azo free.
Direct dyes are used on cellulosic fibers when good light fastness is needed, but wash fastness is not critical. This includes window coverings, upholstery, and heavy bedding where the finished item is seldom washed or is labeled as dry clean only.
Structural characteristics and classification of direct dyes are discussed. Chemistry of benzidine-free direct dyes and after-treatment dyes is also discussed.
With regard to their solubility, organic colourants fall into two classes dyes and pigments. The key distinction is that dyes are soluble in water and/or an organic solvent, while pigments are insoluble in both types of liquid media. Dyes are used to colour substrates to which they have affinity.
Dyes containing one or more azo groups (i.e. azo dyes) comprise by far the largest family of organic dyes. Prominent types are acid dyes for polyamide and protein substrates such as nylon, wool, and silk, and direct and reactive dyes for cellulosic substrates such as cotton, rayon, linen, and paper. Generally, the synthesis of azo dyes involves two steps. Step 1 is the conversion of an aromatic amine to a diazo compound (i.e. Ar-NH2 → Ar-N2+), a process known as diazotization, and step 2 is the reaction of the diazo compound with a phenol, naphthol, aromatic amine, or a compound that has an active methylene group, to produce the corresponding azo dye, a process known as diazo coupling.
Dyes are retained on the fiber by hydrogen bond and van der waal force. Though light fastness of Direct dye is good.
As the dye particles are small and water soluble, it exhibits poor wet fastness. Though it can be improved by after-treatments.
This dyes are superior to others in terms of cost, better light fastness, ease of application, shorter dye cycle, low cost of auxiliaries, remarkably lesser use of water and much lower salt level in effluent.
Direct dyes are also called Substantive dyes. This dyes have direct affinity to the fibers and adheres to the fiber by non-ionic forces. Dyeing process is cheaper. Dyes split up in water forming dye anion and sodium cation.
Direct dyes are mainly used to dye cellulosic fabric, paper, leather etc. Articles that are seldom washed like window covering, upholstery and heavy bedding or labeled as “Dry clean only” are dyed with this dye.
Properties of Direct dyes:
- Anionic in nature
- Good light fastness
- Poor wash fastness because of smaller particles with good water solubility which can be improved by further after-treatment
- Mainly applied on cellulosic fibers but suitable for protein fibers also like nylon, silk and wool
- Shorter dying cycle
- Ease of application