Sulphur dyes are one of the most used dyes for producing bright black and brown shade on cellulosic fiber products. The chemistry of sulphur dyes dyeing is near similar to vat dyes dyeing. In both cases, the final colour is developed by the oxidation process. Although, reactive dyes, azoic colour is available sulphur dyes are preferable for black shade production.
Sulfur dyes are so-called because sulphur dyes contain di-sulphide (S-S) linkage in their chemical structure. The sulphur dyes dyeing process is carried out in alkaline conditions. The sulphur dyes are used for both dyeing and printing.
Properties of Sulphur Dyes:
The following are the properties of sulphur dyes. They are-
- Sulphur dye is water insoluble dye.
- It needs solubilization for application (with reducing agent).
- Oxidation is needed for final color development.
- Sulphur dye is applied in alkaline condition.
- Electrolyte can be added in the dye to enhance exhaustion of dyes.
- Fastness properties are average.
- Best suitable for producing black and brown shade on the textile materials.
- It is mainly applied on cotton, viscose and staple fiber.
- Its exhaustion properties are good.
- Most of the times dyeing is carried out in 80-95 degree Celsius.
- Sulphur dye is comparatively cheap in price.
Types of Sulphur Dyes:
There are many ways to classify sulphur dyes but the following types are based on solubility. They are-
- Conventional or Water insoluble dyes
- Solubilised Sulphur dyes.
- Leuco Sulphur dyes (Partially soluble)
Uses of Sulphur Dye:
There is some application field of sulphur dyes uses. The following are the uses of sulphur dyes. They are-
- Firstly it use to dye cotton fabric such as lining boot.
- Secondly, sulphur dye use to dye Umbrella cloth with Sulphur black.
- Lastly, it use to dye rubber materials when after treatment is essential with CuSO4.
Limitation of Sulphur Dye Uses:
Although sulphur dyes have a lot of advantage it has some disadvantage like-
- Bronziness of shade: For this defect some white spot can be appear in the fabric.
- Sulphur black tendency: This have sulphur black tendency.
So, when you will choose your dyes; check out the properties which should have dyes.