Vat acid dyeing of textile fibers
AssigneeE. I. Du Pont de Nemours and Company
InventorsStephen M. Birkinshaw, Samit N. Chevli, Michael O. Hunt, Jr., Lee D. Jones, David M. Lewis, David J. Marfell
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Abstract
A process for dyeing certain textile fibers, utilizing vat acid dyeing and specific additional (second) reducing agents such as α-hydroxyalkylsulfinic acids, their salts and 1,2,4-trithiolane, resulting in excellent depth of shade and washfastness, is provided.
Claims11
A process for dyeing a fiber comprising a synthetic polymer selected from the group consisting of segmented polyurethanes, segmented polyurethaneureas, segmented polyetheresters, polyesters, polyamides, and poly(meta-phenylene isophthalamide), comprising the steps of:
- (a) preparing a vat acid dye by:
- (i) reducing a vat dye with a first reducing agent in water in presence of a surfactant at an alkaline pH;
- and
- (ii) lowering the pH by the addition of a carboxylic acid;
- (b) forming a dyebath by combining:
- (i) said vat acid dye;
- (ii) an aqueous solution of a carboxylic acid having a pH of about 5.2-6.5;
- and
- (iii) a second reducing agent in an amount sufficient to maintain said dye in a reduced state, wherein said second reducing agent comprises at least about 20 mole %, based on the total of said second reducing agent, of a compound selected from the group consisting of α-hydroxyalkyl-sulfinic acids having 1-6 carbon atoms, water soluble salts thereof, 1,2,4-trithiolane and mixtures thereof;
- (c) contacting said fiber with said dyebath and heating to at least about 95° C. for a time sufficient to dye the fiber;
- and
- (d) oxidizing the dye in the fiber.
A process for dyeing a fiber comprising a synthetic polymer selected from the group consisting of segmented polyurethanes, segmented polyurethaneureas, and segmented polyetheresters, comprising the steps of:
- (a) preparing a vat acid dye by:
- (i) reducing a vat dye with a first reducing agent in water in presence of a surfactant at an alkaline pH;
- and
- (ii) lowering the pH by the addition of a carboxylic acid;
- (b) forming a dyebath by combining:
- (i) said vat acid dye;
- (ii) an aqueous solution of a carboxylic acid having a pH of about 4.0-6.9;
- and
- (iii) a second reducing agent in an amount sufficient to maintain said dye in a reduced state, wherein said second reducing agent comprises at least about 20 mole %, based on the total of said second reducing agent, of a compound selected from the group consisting of α-hydroxyalkyl-sulfinic acids having 1-6 carbon atoms, water soluble salts thereof, 1,2,4-trithiolane and mixtures thereof;
- (c) contacting said fiber with said dyebath and heating to at least about 95° C. for a time sufficient to dye the fiber;
- and
- (d) oxidizing the dye in the fiber.
Dependencies are inferred from the claim text.