Benzimidazolone Orange is a staining, yellowish orange pigment that can become dull in tints. It has an average drying time, and it loses some of its intensity as it dries. The yellowish orange varieties are more transparent.
Benzimidazolone Orange has excellent lightfastness and outstanding heat and solvent stability for a monoazo pigment.
Benzimidazolone Orange is not considered toxic.
The benzimidazolone group of pigments was developed and patented in 1960 by Hoechst A.G., a German chemical manufacturer that was a forerunner of the pharmaceutical company Aventis. Use of benzimidazolone pigments in the auto industry, especially Benzimidazolone Orange, became common in the 1980s because they were common replacements for lead chromate pigments, which were phased out during this period.
Permanent Yellow PY97 ranges from reddish yellow to greenish yellow with temperature shifts from cool to warm hues. It has good tinting strength and average to slow drying time. Similar in shade to Hansa Yellow 1, it offers much better fastness properties and good heat stability.
Pigment PY97 has excellent lightfastness, particularly in the darker shades.
No significant acute hazards of PY97 are known, though chronic hazards have not been well studied.
Hansa Yellows were first made in Germany just before WW1 from a series of synthetic dyestuffs called Pigment Yellow. They were intended to be a synthetic replacement for Cadmium Yellow. Permanent Yellow (PY97) represents a further development of this line, with the aim of producing a yellow pigment that is suitable for exterior use.