Cerdec Aktiengesellschaft Keramische Farben

Degussa Aktiengesellschaft

Ferro Corporation

Dmc, Inc

Hans-Peter Letschert

Martin Jansen

Dietrich Speer

Wilfried Voigt

George E Sakoske

Terry J Detrie

Stephan Ludwig

Eberhard G&uuml;nther

Jenny Wilfert

A green pigment is a blend of metal oxides including a [124] spinel which can contain certain combinations of lithium, sodium, cobalt, zinc, calcium, magnesium, copper, titanium, manganese, tin, and germanium, and a [134] spinel which can contain certain combinations of lithium, sodium, chromium, boron, iron, manganese aluminum, titanium, tin and germanium. The pigment lacks nickel.

Nickel-free green pigment

The invention relates to a display screen, in particular a color display screen, based on a display screen support with a single-layer or multi-layer coating which contains a red luminous substance and a coloring pigment. The invention is furthermore directed towards the display screen coating, means for the production thereof and a coated red luminous substance capable of being used for this purpose. A feature of the invention, is the presence of red tantalum (V) nitride by way of pigment for the purpose of increasing the contrast and decreasing the reflection of the display screen.

Display screen, in particular a color display screen, coating of the same and means for producing the coating

Nitride or oxidenitride based red to yellow pigments, such as tantalum(V) nitride and oxidenitrides containing tantalum may be produced by passing ammonia over nitridable metal compounds, in particular oxide compounds, at 700 to 1250&deg; C. According to the invention, nitriding proceeds in a rotary tube or fluidised bed reactor in the presence of an oxide from the series SiO , ZrO , GeO , SnO , TiO and HfO under conditions under which this oxide is substantially not nitrided.

Process for the production of yellow to red pigments based on nitrides and oxidenitrides

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.

Tantalum (V) nitride pigments, process for the production thereof and use thereof

Purple pigments according to the invention based on a stovable support material, in particular a glass frit, having a coat applied by coprecipitation of an oxide hydrate of one or more elements from the range comprising Al, Si, Sn, Pb, Ti, Nb, Ta, Sc, Y, La, Ce and Zn and a water-insoluble gold compound or colloidal gold are distinguished from prior art pigments of a similar composition by improved color stability in high temperature firing. The pigments are obtainable in the aqueous phase by coprecipitation of an oxide hydrate and a gold compound or colloidal gold in the presence of a support material and in the absence of a reducing agent. Pigments containing gold compounds assume a purple color on heat treatment or by chemical reduction. Preferred pigments containing gold compounds, which may directly be used as decorative colorants, conveniently develop their color during firing of the decoration.

Pigments for the production of purple ceramic decoration, process for

Colored pigments are provided from the green-yellow to red spectrum based on oxide-nitrides with two or three different cations Q, R and S in the crystal lattice, wherein the nitrogen to oxygen atomic ratio is determinative for the color. These pigments crystallise in the pyrochlore, spinel or elpasolite structure. Pigments in the perovskite are as provided with increased color brilliance. The color of the pigments can be adjusted in a wide range of the color spectrum during their preparation within a substance class with the cations Q, R and S and while retaining the crystal structure, by increasing or lowering the atomic ratio N to O in the oxide-nitride and bringing about the required charge balancing by replacing an equivalent quantity of the cation Q with the valency q by a cation R with the valency q+1. In order to prepare the pigments, a mixture of oxide-nitride-forming metal compounds in the atomic ratio of the cations according to the structural formula is calcined, preferably in the presence of mineralizers, under nitriding conditions at 700.degree.-1250.degree. C.

Colored pigments based on oxide-nitrides, the preparation and use thereof

Oxonitrides with a perovskite of the general formula LnTaOn.sub.2, where Ln is a rare-earth element, and which exhibit an enhanced brightness, are produced by annealing a powder mixture consisting of a Ta (V) compound and a Ln compound in a reducing atmosphere that contains ammonia. Added to the powder mixture being annealed is a mineralizing agent from the series of alkali metal or alkaline earth halides, Na.sub.3 AlF.sub.6, Na.sub.2 SiF.sub.6, AlF.sub.3 or of the ammonia salts of carbonic acid or a mono- or dicarboxylic acid with 1 to 4 C atoms in a quantity of 0.1 to 10 parts by weight, relative to 1 part by weight of the mixture of the Ta and Ln compounds. Such oxonitrides can be used as pigments that are yellow-orange to reddish brown in color.

Oxonitrides of the formula LnTaON.sub.2 with enhanced brightness and a

An improved method for producing tantalum (V) nitride by means of nitriding an oxidic tantalum (V) compound is described. The Ta.sub.3 N.sub.5 product obtained in accordance with this method may be used as a red coloring pigment, particularly for coloring plastics and varnishes. An improved color intensity can be achieved and/or the reaction time can be shortened using the process in accordance with the invention. The process includes nitriding tantalum (V) hydrated oxide with the composition of the formula Ta.sub.2 O.sub.5. aq with a hydrate content (i.e., aq content) in a range of 14 to 17% by weight. The nitridation preferably takes place in the presence of a fluxing agent such as ammonium carbonate or boric acid.

Process for using tantalum (V) nitride as a pigment and the colored

Oxonitrides with a perovskite of the general formula LnTaON.sub.2, where Ln is a rare-earth element, and which exhibit an enhanced brightness, are produced by annealing a powder mixture consisting of a Ta (V) compound and a Ln compound in a reducing atmosphere that contains ammonia. Added to the powder mixture being annealed is a mineralizing agent from the series of alkali metal or alkaline earth halides, Na.sub.3 AlF.sub.6, Na.sub.2 SiF.sub.6, AlF.sub.3 or of the ammonia salts of carbonic acid or a mono- or dicarboxylic acid with 1 to 4 C atoms in a quantity of 0.1 to 10 parts by weight, relative to 1 part by weight of the mixture of the Ta and Ln compounds. Such oxonitrides can be used as pigments that are yellow-orange to reddish brown in color.

Oxonitrides of the formula LnTaOn.sub.2 with enhanced brightness and a

An improved method for producing tantalum (V) nitride by means of nitriding an oxidic tantalum (V) compound is described. The Ta.sub.3 N.sub.5 product obtained in accordance with this method may be used as a red coloring pigment, particularly for coloring plastics and varnishes. An improved color intensity can be achieved and/or the reaction time can be shortened using the process in accordance with the invention. The process includes nitriding tantalum (V) hydrated oxide with the composition of the formula Ta.sub.2 O.sub.5 .multidot.aq with a hydrate content (i.e., aq content) in a range of 14 to 17% by weight. The nitridation preferably takes place in the presence of a fluxing agent such as ammonium carbonate or boric acid.

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Hanau, Germany

Hans-Peter Letschert