Dye composition
AssigneeYorkshire Chemicals Limited
InventorsChristopher Whitham, Alan John Buckley, Rebecca Jane Crowson
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Abstract
The invention provides a dye composition for dyeing fibers comprising (a) an azo dye of formula (II) or a salt thereof, and (b) an azo dye of formula (III) or a salt thereof. The invention provides navy and black dye compositions, especially suitable for dyeing secondary cellulose acetate fibers, with superior fastness properties than known navy/black dyes. Preferably, the α-crystal form of dye (III) is used, which has greater solubility and achieves quicker dyeing than the commonly-used β and γ forms of (III) when dyeing cellulose acetate at 60-95° C. A new method of making the α form is disclosed.
Claims29
A dye composition for dyeing fibres comprising
- (a) an azo dye of the formula (II):
- and
- (b) an azo dye of the formula (III):
A method of making an α-form of an azo dye of the formula (III)
- wherein the α-form is characterised substantially by an X-ray diffraction graph (CuKα radiation) having a characteristic line of strong intensity at a diffraction angle 2θ of 25.5°, and lines of medium intensity at diffraction angles of 5.9°, 12.1°, 13°, 14.2°, 15.9°, 17.8°, 18.4°, 24.1°, 26° and 28°;
- the method comprising the steps of:
- (a) reacting 3-amino-5-nitro-2,1-benzothiazole or a salt thereof with a diazotising agent, and
- (b) coupling the diazotised benzothiazole with N-ethyl-N-[2-(methoxycarbonyl)ethyl]aniline or a salt thereof.
Dependencies are inferred from the claim text.