| 摘要 |
The invention relates to a novel crystallographic modification ( beta -modification) of the pigment of the formula I <IMAGE> The beta -modification has reflections in the Cu-K alpha radiation X-ray diffraction spectrum at the following diffraction angles 2 nu (error +/- 0.2 DEG ): at 21.95 DEG a maximum of high intensity, at 5.40 DEG , 7.30 DEG , 10.85 DEG , 14.50 DEG and 27.60 DEG maxima of medium intensity and at 10.05 DEG , 12.80 DEG , 16.40 DEG , 17.95 DEG , 24.65 DEG and 25.80 DEG maxima of low intensity. The beta -modification is obtainable by coupling diazotised N-(3-amino- 4-methylbenzoyl) sulphanilic acid in an aqueous medium in the presence or absence of an organic solvent with alkali-dissolved N-(4-methoxyphenyl)-2-hydroxy-3-naphthamide and laking the end product with calcium salts, at least one cationic surfactant being added not later than prior to the laking step, and heating an aqueous suspension of the laked azo dye to a temperature of 130 to 180 DEG C. The beta -modification is suitable for pigmenting printing inks, lacquers, plastics, artificial silks and paper, in particular for pigmenting polystyrene, copolymers based on polystyrene, polyolefins, copolymers of polyolefins and polyvinyl chloride.
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