Vat Dyes and Their Application

نویسنده

  • R.
چکیده

ong before the advent of systematic L physical sciences and the growth of the chemical industry, as long as 5000 years ago in India, dyeing methods were being used for the application of the water insoluble pigment, indigo, to natural fibers. In the early nineteenth century, between the first cotton gin and the Civil War, the value of natural indigo produced in South Carolina exceeded that of rice or cotton. Indigo was first recovered from the water soluble glucoside of indoxyl (indican) present in the plants Indigofera and Zsatis tinctoria, and then the insoluble blue product was dissolved in wooden vats by a natural fermentation process later known as vatting. This was the origin of the name vat dyes. Chemically speaking, vatting is a reduction. In the right conditions, the known animal and vegetable (cellulosic) fibers accepted the greenish-yellow material dissolved in the vat, and on subsequent exposure of the dyed fibers to the oxygen in the air, the color was converted back to that of the original indigo pigment. Restoration of the indigo is an oxidation. Both oxidation and reduction will be discussed

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تاریخ انتشار 2003