Veeraco Colourants Private Limited is the leading Sulphur Dyes manufacturers in India. Sulphur dyes are in demand to dye cotton and regenerated cellulose/viscose in the form of Yarn, piece goods, or as an item in combinations.
Insoluble in water they are made soluble (leuco) by placing them in an alkaline reducing agent such as Sodium Sulphide (Na2s). Sulphur dyes can be singled out by their dark colors mostly black, blue, or brown required by different sectors.
Sulphur dyes are complex heterocyclic molecules or combinations that are made by melting or boiling organic compounds having amino or nitro groups with sodium polysulphide and sulphur. Sulphur dyes get their name from the fact that all of their molecules contain a sulphur bond.
Features of Sulphur Dyes:
- Sulphur dyes contain a Sulphur bond inside their molecules
- Sulphur dyes are water-insoluble dyes with high coloured content. Some colours are only partially water-soluble.
- They have no direct attraction to cellulosic fibres. They must be transformed into soluble lucoform using reducing agents to become substantial (Like dilute Na2S solution).
- Sulphur dyes have a lightfastness grade of approximately four. An after-treatment with metallic salt may help to increase lightfastness.
- These dyes have a wash fastness value of 3-4, which is outstanding. Because of its higher molecular size and insolubility in water, it has a good wash fastness.
- Due to the severe alkaline condition, they are not suitable for wool.
- They are all amorphous, with only a few showing crystallinities.
- Essential for producing a wide range of colours on various cotton and rayon fabrics.
- Sulphur dyes are good for dark, long-lasting colours.
- Powder and soluble forms are both available
- Sulphur dyes are inexpensive and simple to make.
- Sulphur dyes have moderate to good heat and chemical resistance. They are not used on objects that have been bleached with hypochlorite because of their weak chlorine fastness.
Characteristics of Sulphur Dyes:
- Amorphous Colloidal Materials.
- Molecules have a high molecular weight and a variety of compositions.
- Heterocyclic compounds with Sulphur linkage have a complex chemical structure.
- Acids decompose it, releasing hydrogen sulphide (H2S).
- The thiozine ring, which contains a Sulphur atom, is a distinguishing feature.