Copper phthalocyanine blue
Copper phthalocyanine blue is one of the most important organic pigments ever made: intensely strong, durable and stable enough for automotive and exterior coatings.
Phthalocyanine blue is a large, flat macrocycle of four isoindole units coordinated around a copper atom, C₃₂H₁₆CuN₈ (molecular weight about 576 g/mol). In the Colour Index it is Pigment Blue 15, with subtypes for crystal form and stabilization:
Phthalo blue is used for blues and, mixed with yellows, greens in almost every coating segment: automotive, industrial, architectural, powder, coil and inks. Its tint strength means small amounts give deep color, so it is also used to tint whites and adjust shades.
Copper phthalocyanine is insoluble and has low toxicity; it is generally not classified as hazardous. Handle dry powder with dust control and respiratory protection, and follow the SDS.
PB 15:3 is the beta crystal form, a greener and very stable blue. PB 15:1 is the stabilized alpha form, a redder blue.
Phthalo blue can flocculate, so the pigment separates from whites in the wet film. A rub-out test shows it. Better dispersants or a non-flocculating grade usually fix it.
It contains copper bound in a very stable, insoluble complex and is not considered a heavy-metal pigment in the way lead or chromium pigments are. Check the SDS and any regulations that apply to your market.
