Лако-красочные материалы — производство

The color of most Pc’s ranges from blue-black to metallic bronze, depending on the manufacturing process. Ground powders exhibit colors from green to blue. Most compounds do not melt but sublime above 200°C, which can be used for purification.

H2Pc, CuPc, and halogenated phthalocyanines have very poor solubility in organic solvents. Only in some high-boiling solvents such as quinoline, trichloro­benzene, and benzophenone is recrystallization possible at higher temperature. However, the solubilities have a maximum of several milligrams per liter. In com­mon solvents such as alcohols, ethers, or ketones the solubility is considerable lower.

Phthalocyanine and its unsubstituted metal derivatives dissolve in highly acidic media such as concentrated sulfuric acid, chlorosulfuric acid, or anhydrous hydrofluoric acid, presumably due to protonation of the bridging nitrogen atoms [38-40]. In the presence of strong bases, reversible deprotonation of the central imino groups occurs [40]. The solubility in sulfuric acid depends on temperature and concentration [41]. The rate of decomposition of CuPc increases with increasing H2SO4 concentration, reaching a maximum at about 80% H2SO4 . The stability of metal phthalocyanines increases in the order: ZnPc<CuPc<CoPc< NiPc<CuPcCl15 [42]. The color of phthalocyanine solutions in sulfuric acid depends on the degree of protonation (the N atoms of the ring systems are pro — tonated by H2SO4; metals such as Cu influence this protonation): H2Pc gives a brownish yellow color; CuPc, greenish yellow to olive. The phthalocyanines can be precipitated from these solutions by addition of water. Solubility can be improved in some cases by reversible oxidation with organic peroxides or hypo­chlorites; the Pc’s are oxidized to substances soluble in organic solvents, from which they can be regenerated by reduction [43].

Both H2Pc and its derivatives exhibit high thermal stability. For example, CuPc can be sublimed without decomposition at 500-580°C under inert gas and normal pressure [7]. In vacuum, stability up to 900 °C has been reported [44]. Polychloro CuPc is thermally stable up to 600 °C in vacuum. At higher tempera­ture it decomposes without sublimation. CuPc decomposes vigorously at 405- 420°C in air. In nitrogen, sublimation and decomposition occur simultaneously at 460-630°C [45,46]. Generally all metal Pc’s are more stable thermally in N2 than in O2. CuPc changes from the a — to the |3-form at 250-430°C [47].