[Object] An object of the present invention is to provide a high-aspect-ratio plate-like alumina particle having low aggregability and high dispersibility and a method for producing the particle. [Solving Means] The above problem is solved by providing a plate-like alumina particle including a step of firing an aluminum compound in the presence of a shape-controlling agent and a molybdenum compound serving as a fluxing agent. The above problem is solved also by providing a method for producing a plate-like alumina particle, the method including a step in which the aluminum compound and the molybdenum compound react with each other to form aluminum molybdate and a step in which the aluminum molybdate is decomposed to obtain the plate-like alumina particle.

Effect pigments based on Al.sub.2O.sub.3 flakes with high weather resistance and less photoactivity and to their use thereof in paints, industrial coatings, automotive coatings, printing inks, cosmetic formulations. The effect pigments have a ratio of the amount by weight of Al.sub.2O.sub.3 of the Al.sub.2O.sub.3 flake and the amount by weight of the metal oxide(s) of the coating layer(s) in the range of from 27:73 to 83:17 based on the total weight of the effect pigment.

Effect pigments based on Al.sub.2O.sub.3 flakes with high weather resistance and less photoactivity and to their use thereof in paints, industrial coatings, automotive coatings, printing inks, cosmetic formulations. The effect pigments have a ratio of the amount by weight of Al.sub.2O.sub.3 of the Al.sub.2O.sub.3 flake and the amount by weight of the metal oxide(s) of the coating layer(s) in the range of from 27:73 to 83:17 based on the total weight of the effect pigment.

This invention deals with effect pigment mixture comprising platelet-like aluminum effect pigments obtained by grinding of aluminum or aluminum based alloy shot and silvery pearlescent pigments, wherein the silvery pearlescent pigments are taken from the group consisting of: a) pearlescent pigments comprising a transparent substrate which is coated with a high-refractive index layer with n>1.8, which comprises or consists of an iron-oxide with Fe(II)-ions, b) pearlescent pigments comprising a transparent substrate which is coated with a high-refractive index layer with n>1.8, which comprises or consists of titanium suboxide or a pearlescent pigment comprising a substrate with a high-refractive index with n>1.8 layer, which comprises or consists of a titanium suboxide that is optionally coated with a high-refractive index layer with n>1.8, c) pearlescent pigments comprising a transparent substrate which is coated with a high-refractive index layer with n>1.8, which comprises or consists of titanium oxynitride, d) pearlescent pigments comprising a transparent substrate which is coated with a layer comprising carbon, wherein the carbon is enclosed in a particulate form in another metal oxide layer or is formed as a separate, individual layer, e) a transparent substrate coated with a first layer comprising or consisting of a mixture of the oxides of titanium, iron and at least one of cobalt and chromium and a second layer on the first layer, wherein the second layer comprises an oxide of titanium, and mixtures or combinations of the pearlescent pigments a) to e) or pearlescent pigments with mixtures or combinations of the various coating layers mentioned in the pearlescent pigments a) to e), wherein the weight ratio of the pearlescent pigment to the aluminum effect pigment is in a range of 0.4 to 5.0. The invention deals also with a coating formulation containing this effect pigment mixture.

A pearlescent pigment for security purposes according to an embodiment of the present invention includes a single or a plurality of coating layers containing a metal oxide and an organic or inorganic fluorescent material. Since the pearlescent pigment for security purposes according to the present disclosure includes a fluorescent layer containing the organic or inorganic fluorescent material, it can be used as a pigment for security purposes due to its optical characteristics and can also provide effects such as magnetism, high color intensity, multiple colors, etc. Also, since the pearlescent pigment for security purposes has aesthetic benefit and security characteristic at the same time, it is economical, easy to use and applicable in various industries.

Temperature-stable effect pigments based on multicoated flake-form substrates, and the use thereof in paints, coatings, printing inks, plastics and in particular in glazes, enamels, ceramic or glass-like materials.

This invention deals with effect pigment mixture comprising platelet-like aluminum effect pigments obtained by grinding of aluminum or aluminum based alloy shot and silvery pearlescent pigments, wherein the silvery pearlescent pigments are taken from the group consisting of: a) pearlescent pigments comprising a transparent substrate which is coated with a high-refractive index layer with n>1.8, which comprises or consists of an iron-oxide with Fe(II)-ions, b) pearlescent pigments comprising a transparent substrate which is coated with a high-refractive index layer with n>1.8, which comprises or consists of titanium suboxide or a pearlescent pigment comprising a substrate with a high-refractive index with n>1.8 layer, which comprises or consists of a titanium suboxide that is optionally coated with a high-refractive index layer with n>1.8, c) pearlescent pigments comprising a transparent substrate which is coated with a high-refractive index layer with n>1.8, which comprises or consists of titanium oxynitride, d) pearlescent pigments comprising a transparent substrate which is coated with a layer comprising carbon, wherein the carbon is enclosed in a particulate form in another metal oxide layer or is formed as a separate, individual layer, e) a transparent substrate coated with a first layer comprising or consisting of a mixture of the oxides of titanium, iron and at least one of cobalt and chromium and a second layer on the first layer, wherein the second layer comprises an oxide of titanium, and mixtures or combinations of the pearlescent pigments a) to e) or pearlescent pigments with mixtures or combinations of the various coating layers mentioned in the pearlescent pigments a) to e), wherein the weight ratio of the pearlescent pigment to the aluminum effect pigment is in a range of 0.4 to 5.0. The invention deals also with a coating formulation containing this effect pigment mixture.

The invention relates to effect pigments comprising artificial platelet-shaped substrates which have at least one optically active coating, where the effect pigments have a volume-averaged cumulative undersize distribution curve with the characteristic numbers D.sub.10, D.sub.50 and D.sub.90, said cumulative undersize distribution curve having a span ΔD of 0.7-1.4, and the span ΔD being calculated in accordance with formula (I):
ΔD=(D.sub.90−D.sub.10)/D.sub.50  (I),
and the average thickness of the artificial platelet-shaped substrates being 500 nm to 2000 nm.

A golden effect pigment comprising an optionally passivated platelet-shaped metallic substrate and an iron oxide layer, wherein the effect pigment has a hue angle h.sub.15 of 67°≤h.sub.15≤78° and a chroma C*.sub.15 of ≥90 is provided. Further, a golden effect pigment comprising an optionally passivated platelet-shaped metallic substrate and an iron oxide layer, wherein the effect pigment has a hue angle h.sub.15 of 67°≤h.sub.15≤78° and a chroma C*.sub.45 of ≥50 is provided. The golden effect pigments are highly chromatic and suitable for coloring a coating composition such as a paint, a printing ink, an ink, a varnish, plastics, a fiber, a film or a cosmetic preparation, preferably an automotive, an architectural or an industrial coating composition.

The present invention relates to a pigment mixture based on spherical particles having a defined particle-size distribution, and to the use thereof in paints, coatings, printing inks, security printing inks, plastics, ceramic materials, glasses, in cosmetic formulations, as tracer, as filler and for the preparation of pigment preparations and dry preparations.