CRYSTALLINE MODIFICATION OF PIGMENT RED 53:1

摘要

A novel crystallographic modification ( beta -modification) of the pigment C. I. Pigment Red 53:1 is described and claimed which has characteristic reflection values in its X-ray diffraction pattern obtained by means of Cu-K alpha radiation. This novel pigment form is obtained by reacting an aqueous solution of an alkali metal or ammonium salt of the formula 1 (1) with the equivalent amount of a water-soluble barium salt in the presence of a compound of the formula 2 (2) The modification is distinguished by a more yellowish-red shade as compared to the known alpha -modification.