Dyeing-stable modification of a disperse dyestuff, processes for its preparation and use

Abstract

A dyestuff useful for dyeing and printing synthetic, hydrophobic fibers or mixtures thereof with cellulose fibers and stable under dyeing conditions is a .beta.-modification of a compound of the formula ##STR1## having an X-ray diffraction pattern under Cu-K.alpha.-radiation with high intensity lines at a diffraction angle in .theta. degrees of 3.75, 6.40 and 12.35; medium intensity lines at a diffraction angle in .theta. degrees of 6.60, 7.30, 7.60, 7.90, 8.10, 8.35, 9.30, 9.70, 9.90, 10.20, 10.50, 12.70 and 13.90; and low intensity lines at a diffraction angle in .theta. degrees of 5.65, 8.75, 11.25, 11.70, 13.35, 15.10 and 15.55; which is prepared by heating at 50.degree.-150.degree. C. the .alpha.-modification of said compound, which is unstable under dyeing conditions.

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