Cerdec Aktiengesellschaft Keramische Farben

Dmc, Inc

Wilfried Voigt

Hans-Peter Letschert

The invention relates to tantalum (V) nitride pigments with improved color values compared with predisclosed products, a process for producing such pigments and their use. According to the invention, pigments having an a* color value in the CIE Lab system of equal to/greater than 45, in particular equal to/greater than 50, are obtainable by after-treating a tantalum (V) nitride produced in a known manner in a salt melt at 100 to 600&deg; C., in particular 300 to 500&deg; C., in the course of 1 to 100 minutes, in particular 5 to 60 minutes. Preferably, the after treatment is carried out in an alkali-metal nitrate melt. The pigments can be used to color plastics and paints, and also enamel, glass and porcelain decorations.

Tantalum (V) nitride pigment, process for producing it and its use

Tantalum(V) oxide may be nitrided with ammonia at 700 to 1250&deg; C. to yield tantalum(V) nitride. According to the invention, nitriding and consequently pigment quality are improved by adding at least one pulverulent oxide from the series SiO,, GeO,, SnO,, TiO,, ZrO,and HfO,or a pulverulent precursor of such an oxide in a quantity of at least 0.1 wt. %, calculated as oxide, to the tantalum(V) oxide to be nitrided and then nitriding the powder mixture.

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Rodenbach, Germany

Wilfried Voigt