Multilayered luster pigments
The invention relates to multilayered luster pigments based on metallic substrates, which are completely surrounded by a plurality of layers, where these layers comprise at least one layer pack (A) having a colorless dielectric layer of a material with a refractive index n of ≦1.8, and a colorless dielectric layer of a material with a refractive index n of >1.8, and a selectively or non-selectively absorbent layer (B), and to a process for their production, and to their use.
1. A multilayered luster pigment comprising a metallic substrate opaque to light and reflective and a plurality of layers, each of said plurality of layers completely or essentially completely surrounding the substrate, comprising
(A) at least one layer pack comprising
i) a colorless dielectric layer of a material having a refractive index n of ≦1.8, and
ii) a colorless dielectric layer of a material having a refractive index n of >1.8, and
(B) an absorbent layer.
2. A multilayered luster pigment according to claim 1 , wherein the metallic substrate is platelet-shaped.
3. A multilayered luster pigment according to claim 1 , further comprising an outer layer (C).
4. A multilayered luster pigment according to claim 1 , wherein the metallic substrate comprises a metal, a metal alloy or a mixture thereof.
5. A multilayered luster pigment according to claim 1 , wherein the material having a refractive index of ≦1.8 for layer i) is a metal oxide, metal fluoride, metal oxide hydrate, metal phosphate or a mixture thereof.
6. A multilayered luster pigment according to claim 1 , wherein the material having a refractive index n of >1.8 for layer ii) is a metal oxide or metal sulfide or a mixture thereof.
7. A multilayered luster pigment according to claim 1 , wherein the absorbent layer comprises an at least partially light-transparent metal or a selectively absorbent metal oxide, metal sulfide, metal nitride or an alloy or a mixture thereof.
8. A multilayered luster pigment according to claim 1 , wherein the metallic substrate comprises iron, steel, stainless steel, aluminum, copper, nickel, chromium, zinc, tin, silver, gold, platinum, cobalt, a lanthanide or titanium or a mixture or an alloy thereof.
9. A multilayered luster pigment according to claim 1 , wherein the material having a refractive index n of ≦1.8 for layer i) is SiO 2 , SiO(OH) 2 , Al 2 O 3 , AlO(OH), B 2 O 3 , MgF 2 , MgSiO 3 or aluminum phosphate or a mixture thereof.
10. A multilayered luster pigment according to claim 1 , wherein the material having a refractive index n of ≦1.8 for layer i) is SiO 2 , Al 2 O 3 or MgF 2 or a mixture thereof.
11. A multilayered luster pigment according to claim 1 , wherein the material having a refractive index n of ≦1.8 for layer i) is SiO 2 .
12. A multilayered luster pigment according to claim 1 , wherein the material having a refractive index n of >1.8 for layer ii) is TiO 2 , ZrO 2 , SiO, CeO 2 , HfO 2 , Pr 2 O 3 , Y 2 O 3 , Ta 2 O 5 , ZnO, SnO 2 , Ce 2 O 3 , BiOCl or ZnS or a mixture thereof.
13. A multilayered luster pigment according to claim 1 , wherein the material having a refractive index n of >1.8 for layer ii) is TiO 2 or ZnS.
14. A multilayered luster pigment according to claim 1 , wherein the material having a refractive index n of >1.8 for layer ii) is TiO 2 .
15. A multilayered luster pigment according to claim 1 , wherein the absorbent layer (B) comprises chromium, tungsten, cobalt, nickel, copper, molybdenum, aluminum, or magnetite, goethite, iron(III) oxide, cobalt oxide, chromium(III) oxide, titanium(III) oxide, titanium suboxide, vanadium oxide, pseudobrookite, ilmenite or cobalt sulfide, nickel sulfide, chromium sulfide, iron sulfide, tungsten sulfide, molybdenum sulfide, cerium sulfide, titanium nitride, titanium oxynitride, or a mixture thereof, or an alloy of two or more metals.
16. A multilayered luster pigment according to claim 1 , wherein the absorbent layer (B) comprises chromium, aluminum or iron(III) oxide.
17. A multilayered luster pigment according to claim 1 , wherein layer i) has a layer thickness of greater than 150 to 1000 nm.
18. A multilayered luster pigment according to claim 1 , wherein layer i) has a layer thickness of 200 to 600 nm.
19. A multilayered luster pigment according to claim 1 , wherein layer ii) has a layer thickness of 30 to 500 nm.
20. A multilayered luster pigment according to claim 1 , wherein layer ii) has a layer thickness of from 200 to 350 nm.
21. A multilayered luster pigment according to claim 1 , wherein the layer pack (A) consists of a layer i) on the platelet-shaped metallic substrate and a layer ii) applied thereon.
22. A multilayered luster pigment according to claim 1 , wherein the layer pack (A) consists of a layer ii) on the platelet-shaped metallic substrate and a layer i) applied thereon.
23. A multilayered luster pigment according to claim 1 , wherein the absorbent layer is selectively absorbent.
24. A multilayered luster pigment according to claim 1 , wherein the absorbent layer is non-selectively absorbent.
25. A multilayered luster pigment according to claim 3 , wherein layer (C) is a colorless or selectively absorbent metal oxide.
26. A process for the preparation of a multilayered luster pigment according to claim 1 , comprising coating a metallic substrate with layers (A) and (B) by a wet-chemical method, a CVD or PVD method, or by a combination thereof.
27. A process according to claim 26 , wherein in the wet-chemical method is precipitation, hydrolysis or reduction of a metal salt in an aqueous or organic medium, or a combination thereof.
28. A composition that is a paint, coating, printing ink, plastic article, cosmetic, ceramic material, paper, glass, dry preparation, pigment or material for a laser, security or decorative marking comprising a pigment according to claim 1 and a suitable carrier.