Pearlescent pigments based on fluorides, oxyfluorides, fluorosulfides and/or oxyfluorosulfides

• US 20040219116A1
• Filed: 02/03/2004
• Published: 11/04/2004
• Est. Priority Date: 02/03/2003
• Status: Abandoned Application

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Bertaux, Stephane, Reynders, Peter, Wichmann, Jens-Uwe
• Application Number:
  US10/769,985
• Publication Number:
  US 20040219116A1
• Time in Patent Office: Days
• US Class Current: 424/63
• CPC Class Codes: A61K 2800/434 Luminescent, Fluorescent; Optical brighteners; Photosensitizers
• CPC Class Codes: C01P 2004/32 Spheres
• CPC Class Codes: C09C 1/0015 Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
• CPC Class Codes: C09C 1/0021 comprising a core coated with only one layer having a high or low refractive index
• CPC Class Codes: C09C 1/0078 Pigments consisting of flaky, non-metallic substrates, characterised by a surface-region containing free metal
• CPC Class Codes: C09C 2200/102 the core consisting of glass or silicate material like mica or clays, e.g. kaolin
• CPC Class Codes: C09C 2200/24 Interference pigments comprising a metallic reflector or absorber layer, which is not adjacent to the core
• CPC Class Codes: C09D 11/50 Sympathetic, colour changing or similar inks
• CPC Class Codes: C09D 5/032 characterised by a special effect of the produced film, e.g. wrinkle, pearlescence, matt finish
• CPC Class Codes: C09D 5/36 Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre

Abstract

The present invention relates to novel pigments based on substrates coated with at least one selectively light absorbing layer of fluorides, oxyfluorides, fluorosulfides and/or oxyfluorosulfides. Metal oxides or mixed metal oxides are coated onto a substrate; the resulting precursor is transferred into a furnace and calcined under a fluoridizing and/or sulfurizing gas flow to convert the oxides into fluorides, oxyfluorides, fluorosulfides and/or oxyfluorosulfides depending on the reaction parameters. The conversion to fluorides, oxyfluorides, fluorosulfides and/or oxyfluorosulfides is preferably carried out in a fluidized bed reactor. Angle-dependent optical pigments are thus produced which are especially useful in paints, powder coatings, paper coatings, plastics, cosmetics, inks and security-enhancing features as well as in decorative applications for foods and drugs.

Claims

1. A pearlescent pigment comprising a substrate and at least one selectively light absorbing layer which consists of a fluoride, oxyfluoride, fluorosulfide and/or oxyfluorosulfide.

2. A pigment according to claim 1, wherein the fluoride, oxyfluoride, fluorosulfide and/or oxyfluorosulfide is of a metal(s) selected from Group 2 and/or 4-16 of the periodic system.

3. A pearlescent pigment according to claim 1, wherein the substrate is a platelet-shaped, spherical or needle-shaped substrate.

4. A pearlescent pigment according to claim 1, wherein the substrate is platelet-shaped and is of mica, SiO₂, aluminum oxide, glass, micaceous iron oxide, oxidized graphite, aluminum oxide-coated graphite, a pearlescent pigment or a pearlescent multilayer pigment.

5. A pearlescent pigment according to claim 1, wherein the substrate is coated or uncoated SiO₂-spheres.

6. A pearlescent pigment according to claim 1, wherein the substrate is needle-shaped iron oxides.

7. A pearlescent pigment according to claim 1, wherein the selectively light absorbing layer is a binary fluoride or fluorosulfide, a ternary fluoride or fluorosulfide, a quaternary fluoride or fluorosulfide or an oxyfluoride or oxyfluorosulfide of one, two or three metals.

8. A pearlescent pigment according to claim 1, wherein the thickness of the selectively light absorbing layer is between 5 and 500 nm.

9. A pearlescent pigment according to claim 1, wherein the pigment is further coated on top of the selectively light absorbing layer with one or more layers of metal oxides, metal oxide hydrates, metal fluorides and/or semitransparent metal layers.

10. A pearlescent pigment according to claim 9, wherein the coating on top is of a metal oxide selected from TiO₂, iron oxide and/or mixtures thereof, and/or a metal selected from Al, Mo and/or Cr.

11. A process for the preparation of a pigment according to claim 1 comprising precipitating a layer of an oxide, hydroxide, mixed oxide and/or mixed hydroxide onto the substrate and then converting the oxide, hydroxide, mixed oxide and/or mixed hydroxide into a fluoride, oxyfluoride, fluorosulfide and/or oxyfluorosulfide.

12. A process according to claim 11, wherein the conversion is carried out in a fluidized bed reactor.

13. A process according to claim 11, wherein the conversion is carried out with a reactive gas which comprises fluorine and/or HF, alone, or in combination with H₂S, CS₂, sulfur or a mixture thereof.

14. A process according to claim 12, wherein the conversion is carried out with a reactive gas which comprises fluorine and/or HF, alone, or in combination with H₂S, CS₂, sulfur or a mixture thereof.

15. A process according to claim 13, wherein, additionally, an inert gas is present during the conversion.

16. A process according to claim 15, wherein the inert gas is Ar or N₂.

17. A process according to claim 11, wherein the substrate is platelet-shaped and is of mica, SiO₂, aluminum oxide, glass, micaceous iron oxide, oxidized graphite, aluminum oxide-coated graphite, a pearlescent pigment or a pearlescent multilayer pigment.

18. The process of claim 11, wherein the substrate is coated or uncoated SiO₂-spheres or needle-shaped iron oxides.

19. A process according to claim 11, wherein the oxide, hydroxide, mixed oxide and/or mixed hydroxide is doped with metal ions, silicon oxide, aluminum oxide, sulfur, phosphate ions and/or sulfate ions.

20. A process according to claim 19, wherein the doping is with metal ions selected from silicon, vanadium, chromium, aluminum, cerium, neodymium, praseodymium, selenium, cobalt, nickel and/or zinc.

21. A paint, powder coating, paper coating, plastic, cosmetic, ink, food or drug composition comprising a pigment of claim 1.

22. A security-enhanced document or article comprising a pigment of claim 1.

23. A phosphorescent, fluorescent or luminescent material for security, optical or projection screen applications, which comprises a pigment of claim 1.