The influence of temperature and duration of treatment of α-Copper Phthalocyanine in toluene was investigated experimentally

and the activation energy E in toluene was calculated to be 60.2 kJ/mol. A comparative study of different types of solvents on the rate of crystal phase transformation of α-Copper Phthalocyanine was carried out

and it was concluded that the solubility of Copper Phthalocyanine played a decisive role in the phasetransformation. The solubilities of α-Copper Phthalocyanine in different solvents could be estimated through the characteristic absorption peaks by means of the photo-electric spectrometer. It was also pointed out that the phase conversion process of α- to β-Copper Phthalocyanine pigment in those solvents where α-phase dissolves only with difficulty

is not related to Ostwald crystal growth.