Colored pigments
The present invention relates to colored pigments based on multicoated platelet-shaped substrates which are distinguished by the fact that they comprise (A) a coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm, (B) a colorless coating having a refractive index of n≦1.8 and a layer thickness of 10-100 nm, (C) a colorless coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm, (D) a covering of absorbent pigment particles having a particle size of 1-500 nm, and optionally (E) an outer protective layer, and to their use in paints, coatings, printing inks, plastics, ceramic materials, glasses, for laser marking, in cosmetic formulations and for the production of pigment preparations and dry preparations.
1. A colored pigment comprising a transparent platelet-shaped substrate which is mica, glass, talc, kaolin, aluminium oxide, SiO 2 , or BiOCl, and thereon
(A) an optionally functional coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm,
(B) an optionally functional colourless coating having a refractive index of n≦1.8 and a layer thickness of 10-100 nm,
(C) an optionally functional colourless coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm,
(D) a covering of absorbent pigment particles having a particle size of 1-500 nm, and
optionally
(E) an outer protective layer.
2. A colored pigment according to claim 1 , wherein the platelet-shaped substrate is natural or synthetic mica, glass platelets, Al 2 O 3 platelets, SiO 2 platelets or TiO 2 platelets.
3. A colored pigment according to claim 1 , wherein layer (A) consists of TiO 2 , ZrO 2 , ZnO or BiOCl.
4. A colored pigment according to claim 1 , wherein layer (B) consists of SiO 2 , MgF 2 or Al 2 O 3 , or mixtures thereof.
5. A colored pigment according to claim 1 , wherein the absorbent pigment particles are Prussian Blue, magnetite, Carmine Red and/or thioindigo or a mixture thereof.
6. A colored pigment according to claim 1 , wherein layer (A) and layer (C) have the same composition.
7. A colored pigment according to claim 6 , wherein layer (A) and layer (C) consist of TiO 2 .
8. A process for the preparation of the colored pigment according to claim 1 , comprising coating of the platelet-shaped substrates by wet-chemical precipitation by hydrolytic decomposition of metal salts in aqueous medium or by CVD or PVD.
9. A paint coating, printing ink, plastic, ceramic material, glass, cosmetic formulation, or laser marking composition, comprising a pigment according to claim 1 .
10. A pigment preparation comprising at least one binder and at least one colored pigment according to claim 1 .
11. A dry preparation, in the form of pellets, granules, chips or briquettes, comprising a pigment in turn comprising
a platelet-shaped substrate, and thereon
(A) a coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm,
(B) a colorless coating having a refractive index of n≦1.8 and a layer thickness of 10-100 nm,
(C) a colorless coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm,
(D) a covering of absorbent pigment particles having a particle size of 1-500 nm, and
optionally
(E) an outer protective layer.
12. A colored pigment consisting of a transparent platelet-shaped substrate which is mica, glass, talc, kaolin, aluminium oxide, SiO 2 , or BiOCl, and thereon
(A) a coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm,
(B) a colorless coating having a refractive index of n≦1.8 and a layer thickness of 10-100 nm,
(C) a colorless coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm,
(D) a covering of absorbent pigment particles having a particle size of 1-500 nm, and
optionally
(E) an outer protective layer.
13. A colored pigment according to claim 1 , wherein layer (A) has a thickness of 40-350 nm, layer (B) has a thickness of 20-80 nm, and layer (C) has a thickness of 40-350 nm.
14. A colored pigment according to claim 1 , having a ratio of layer thickness of (A) or (C) to (B) of 2:1 to 5:1.
15. A colored pigment according to claim 13 , having a ratio of layer thickness of (A) or (C) to (B) of 2:1 to 5:1.
16. A colored pigment comprising a transparent platelet-shaped substrate which is mica, glass, talc, kaolin, aluminium oxide, SiO 2 , or BiOCl, and thereon
(A) an optionally functional coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm,
(B) an optionally functional colorless coating having a refractive index of n≦1.8 and a layer thickness of 10-100 nm,
(C) an optionally functional colorless coating having a refractive index of n>1.8 and a layer thickness of 20-500 nm,
(D) a covering of absorbent pigment particles having a particle size of 1-500 nm, and
optionally
(E) an outer protective layers,
whereby said pigment possesses high hiding power and little or no angle dependence of the interference color.