Vat Dyes

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Vat dyes, including indigo and anthraquinone-based dyes, are chemically complex dyes that retain the C=O chromophore structure. Vat dyes are ideal for colored woven goods such as handkerchiefs, shirting, and toweling. The dyeing procedure of vat dye is not as the same as the other dyes like reactive, direct, azoic, acid or basic dyes. Vat dyes are generally insoluble in water and cannot dye fibers directly. However, they can be solubilized by reduction in an alkaline solution, which allows them to adhere to textile fibers. Subsequent oxidation or exposure to air restores the dyes to their insoluble form.

As a professional supplier of high-efficiency dyes, Alfa Chemistry has the ability to provide customers with a comprehensive range of vat dyes.

Vat Dyes-Lists

Features of Vat Dyes

Vat dyes are insoluble in water, while they are mostly soluble in hot water, and a few are soluble in the presence of little Na2CO3.
These dyes' solubility can be improved by adding urea at 50–60 ° C temperature.
They're typically converted to their soluble leuco state by using sodium hydrosulfite as a reductant in the presence of hydrated oxide (NaOH), i.e. in an alkaline reducing solution.
Oxidation is required for the final color development.
Vat dyes can be dyed both cellulosic and protein fiber, while they are mostly used for dyeing cellulosic fibers.
They have high color fastness, which is uncommon in other dye classes.
They have poor rubbing fastness, but this can be mitigated with special treatments to the fabric.
It should be avoided from sunlight because it is sensitive to light, and ester groups are affected to develop prematurely.
They're commercially available in numerous forms like powder fine.
Sometimes, they can cause skin diseases.
Vat dyes are expensive compared to other classes of dyes.

Mechanism of Vat Dyes

Generally, the application of vat dyes to textile materials involves four distinct steps.

Vatting

In simple terms, vatting is the process of converting the insoluble vat dyes into its soluble form. During the vatting process, reducing agents such as sodium hydrosulfite and sodium hydroxide reduce the carbonyl group of these dyes and convert them into the water-soluble dyes, which have strong affinity for the cellulosic fibers.

Dyeing

Absorption of reduced and dissolved dyestuff by fiber from an alkaline reduction bath. In this stage, the textile material must be immersed in dye liquor to prevent oxidation of leuco compound.

Oxidation

Oxidation is the reconversion of the soluble form of dye absorbed by the fiber to its original insoluble form by atmospheric oxygen or chemical oxidation (i.e. involving the use of a chemical like sodium per borate or potassium dichromate or Hydrogen per oxide).

After-treatment

After the oxidation has been accomplished and the pigmentary form of the vat dye is left embedded within the cellulosic fibers, then comes soaping.

Alfa Chemistry is committed to becoming a first-class, low-carbon, environmentally friendly dye supplier. Our mission is to provide customers with full specifications of high-quality dyes. We are also constantly expanding our product database to meet the wide range of customer needs. You are welcomed to contact us for more vat dyes.

It is important to note that our products are for research use only and are not for clinical use.

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