Non-metallic pigments having metal properties
AssigneeMerck Patent GmbH
InventorsReinhold Rueger, Bjoern Kleist
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Abstract
The present invention relates to non-metallic interference pigments, in particular laminar interference pigments, which comprise a thin high-refractive layer and an outermost layer that contains crystalline carbon in the form of graphite and/or graphene. The invention also relates to a method for producing such pigments and the use of the thus produced pigments.
Claims12
Non-metallic interference pigments based on a flake-form non-metallic support, wherein the pigments have a particle size having a volume-weighted d90 value of <25 μm and a volume-weighted d50 value of <15 μm, the support has a coating comprising one or more successive layers of a colourless material having a refractive index n of n≥1.8 with a geometrical overall layer thickness of at most 70 nm, wherein the pigments have an outermost layer which consists of at least 95% by weight, based on the weight of this layer, of carbon and comprises crystalline carbon in the form of graphite and/or graphene, wherein the outermost, crystalline carbon-containing layer has a geometrical thickness in the range of from 1-3 nm and the proportion of the outermost crystalline carbon-containing layer, based on the weight of the interference pigment, is 1 to 3% by weight, and wherein the pigments have a specific powder resistance of less than 1×106 ohm*cm.
Dependencies are inferred from the claim text.