MUTTENZ, Switzerland – Pigment Violet 23 (PV 23) has now been around for more than 55 years. Its beginnings go back to 1928, when a patent was filed for the pigment after researchers at the Hoechst company in Germany first undertook the multistage synthesis based on carbazole, an ingredient of coaltar, and chloranile. Until the end of World War II the pigment was only used to process diamine light blue, a direct dyestuff for cotton.
With the invention of reactive dyes, which considerably simplified the dyeing and printing process for cellulose fibers, this application lost its importance. A new and promising use for PV 23 was quickly found due to the pigment’s ability to produce unique colors.
PV 23 has been used as a pigment since 1953. PV 23 belongs to the group of high-performance polycyclic pigments (HPP’s) that are used whenever the requirements for a colorant are particularly high. These include high light fastness and weather fastness, fastness to solvents, and heat stability. In addition, PV 23 stands out by its high coloring power. Under the electron microscope, the crude violet shows a highly granular crystalline form, whereas the pigment particles are miniscule.
At Clariant, the world’s largest producer of PV 23, pigments are produced in a global production network in which every plant produces certain product groups. Violet is the specialty of the plant in Frankfurt am Main, Germany, where the PV 23 production was centralized after Clariant took over the Hoechst specialty chemicals business in 1997. At the Frankfurt plant, the five-step synthesis and the finishing of the pigments follow modern production methods and the highest technological standards. The constant analysis of the material flow ensures optimized processes.
Clariant has tailored PV 23 to fit a wide range of applications. Today, the company produces and sells more than a dozen trademarks, from the salt-containing or desalted crude pigment to pigments that are finished for various applications. As a finished pigment, PV 23 is also used as a wet press cake in water-based applications. The largest area of application is printing inks, followed by textile printing, coatings, plastics and special applications.