Method of reducing vat dyes and the process of dyeing fabrics therein

Abstract

A process for reducing vat dyes, such as indigo, into their leuco form by placing a metal, such as aluminum, in water in the presence of a reduction facilitator to form a first solution after which a vat dye having the general structure O.dbd.C(--C.dbd.C--).sub.N C.dbd.O where N=1, 2 or 4 is mixed with the first solution to form a dye solution where substantially all of the vat dye is reduced to its soluble leuco form having the general structure HO--C.dbd.(C--C).sub.N .dbd.C--OH. The process includes dyeing fabric in the dye solution. the reduction facilitator may be a base, for example that produced hydroxide ions in water, and the first solution as well as the dye solution can be a basic solution. The soluble leuco can be isolated from the dye solution and dissolved in a non-aqueous solution. Prior to mixing the vat dye in water, it may first be dissolved in a solvent miscible with water.

Dependencies are inferred from the claim text.