Manufacturing the Different Crystal Modifications

Unsubstituted Copper Phthalocyanine Blue is polymorphous. X-ray diffraction diagrams point to five different crystal modifications (a, (3, y, 8, e) (Fig. 91). The relative thermodynamic stability of the individual cystal phases decreases in the following order (3 e 8 a = y [13-16], 

Among these modifications, it is particularly the phase-stabilized a- and the (3-form that have stimulated commercial interest. 

Crude Copper Phthalocyanine Blue which is prepared by the phthalonitrile or urea process typically evolves as the -modification with a coarse particle size. 

Recently, by crystal structure studies the number of different polymorphs of Copper Phthalocyanine Blue has been extended to nine, various of which are differing mainly in herringbone-type interaction [17]. 

The synthesis of the crystal modification is controlled primarily by the finishing technique of the crude pigment. There are basically two different methods to produce a finely dispersed pigment treatment with acid to form copper phthalocyanine salts, followed by precipitation in water on the one hand, and mechanical treatment (milling, kneading) on the other hand. The following methods are used  

---