The present invention is related to brilliant black pigments comprising a flaky aluminum oxide substrate having a coating comprising a layered structure composed of a hematite and a magnetite layer, to a process for the production of said pigments, as well as to their use.

Disclosed herein is a flaky diffractive effect pigment having a diffractive structure and comprising a flake of a highly reflective material having a first major interface and opposed to this first interface a second major interface, and at least one side surface and directly adjacent on one or of both of these major interfaces a layer of a semiconducting material having a bandgap of 0.7 to 2.5 eV. The diffractive effect pigment may be further coated with a coating which is optically non-active in the visible wavelength region.

Disclosed herein is an effect pigment having a layer stack which comprises a highly reflective metallic flake having a first major interface and opposed to this first interface a second major interface, and at least one side surface and directly adjacent on one or of both of these major interfaces a layer of a semiconducting material having an average atomic composition of: a) Si.sub.(1-x)Sn.sub.x, wherein 0<x<0.90 or b) Ge.sub.(1-y)Sn.sub.y, wherein 0<y0.80 or c) Si.sub.(1-m-n)Ge.sub.mSn.sub.n, wherein 0<m<1.00, 0<n<1.00 and with the proviso that m+n<1.00.

Weather stable pearlescent pigment having a basic pearlescent with an interference color which comprises a transparent platelet-shaped substrate and at least one metal oxide layer with a refractive index >1.8 and on top of this basic pearlescent pigment a weather stabilizing top coating comprising at least one metal oxide and an organofunctional surface modification, wherein a) for a basic pearlescent pigment with silvery interference color the weather stabilizing top coating consists of a first metal oxide of a rare earth metal M1 from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof, or b) for a basic pearlescent pigment with a colored interference color or a silvery interference color the weather stabilizing top coating comprises a first metal oxide of a rare earth metal M1 from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof, and a second metal oxide from a second metal M2 from the group consisting of Si, Al, Zn, Mg, Zr, Sn and mixtures or combinations thereof, and in each case a) or b) the organofunctional surface modification comprises organofunctional silanes or water-based pre-condensated organofunctional silanes.

This invention involves a coated flaky metal effect pigment comprising a metal effect flake as substrate coated by the following consecutive coating sequences: a) optionally a discontinuous or a continuous layer of Mo-oxide, b1) an inorganic metal oxide layer comprising mainly SiO.sub.2, c1) a hybrid layer comprising SiO.sub.2 modified by a diphenyl silane, a phenylsilane or mixtures thereof or c2) a hybrid layer comprising SiO.sub.2 modified by a diphenyl silane, a phenylsilane or mixtures thereof, b2) an inorganic metal oxide layer comprising mainly SiO.sub.2, and d) optionally a further top-coat of organofunctional silanes, titanates, aluminates or zirconates.

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.

Weather stable pearlescent pigment having a basic pearlescent with an interference color which comprises a transparent platelet-shaped substrate and at least one metal oxide layer with a refractive index >1.8 and on top of this basic pearlescent pigment a weather stabilizing top coating comprising at least one metal oxide and an organofunctional surface modification, wherein a) for a basic pearlescent pigment with silvery interference color the weather stabilizing top coating consists of a first metal oxide of a rare earth metal M1 from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof, or b) for a basic pearlescent pigment with a colored interference color or a silvery interference color the weather stabilizing top coating comprises a first metal oxide of a rare earth metal M1 from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof, and a second metal oxide from a second metal M2 from the group consisting of Si, Al, Zn, Mg, Zr, Sn and mixtures or combinations thereof, and in each case a) or b) the organofunctional surface modification comprises organofunctional silanes or water-based pre-condensated organofunctional silanes.

The present invention is related to effect pigments exhibiting a deep black body color as well as a blue interference color, to a process for the production of such pigments as well as to the use thereof, especially in coating compositions.

Interference pigments based on SiO.sub.2 flakes coated with crystallites of alpha-Fe.sub.2O.sub.3. Also, a process for the preparation of interference pigments that comprise SiO.sub.2 flakes coated with a crystallite of alpha-Fe.sub.2O.sub.3, by a wet-chemical process in a fluidised bed, by a CVD process, by a PVD process, or by any combination of said processes. Also, the use of interference pigments based on SiO.sub.2 flakes coated with crystallites of alpha-Fe.sub.2O.sub.3, in particular in paints, coatings, industrial and automobile paints, ceramic materials, plastics and cosmetic formulations.

The present invention is directed to effect pigments with solvochromic properties. These effect pigments have a structure comprising a substrate in platelet form and a coating applied to the substrate, wherein the coating comprises: optionally a layer (1) comprising or consisting of at least one of tin oxide, tin hydroxide and/or tin oxide hydrate, a layer (2) comprising at least one of metal oxide, metal hydroxide and/or metal oxide hydrate, and a layer (3) comprising at least one of metal oxide, metal hydroxide and/or metal oxide hydrate, wherein the layers (2) and (3) comprise in their metal oxide, metal hydroxide and/or metal oxide hydrate in a majority two different metal ions from the group consisting of Ti, Fe, Sn or Zr and a further spacer layer (4) being located in between layers (2) and (3), wherein layer (4) has a porous structure comprising cavities and connectors. The solvochromic properties denote to the effect pigment having a first interference color under ambient atmosphere which changes reversibly to a second interference color, when the effect pigment comes into contact with a solvent.