Iridescent magnetic effect pigments comprising a ferrite layer
Iridescent magnetic pigments are produced by depositing a ferrite layer and a second metal oxide layer in succession on a substrate. The substrate may be platy and is coated with the ferrite, which is then coated with the second metal oxide layer to provide interference color effect. At least one of the layers is magnetic. The magnetic pigment may be used in coatings such as paints.
1. A magnetic effect pigment comprising:
(a) a substrate;
(b) at least one ferrite layer deposited on said substrate; and
(c) deposited on said ferrite layer, at least one non-ferrite metal oxide layer being an interference color imparting layer and being formed by calcination at about 600-800° C.
2. The magnetic effect pigment of claim 1 wherein said ferrite layer comprises a double oxide of iron oxide and another metal oxide.
3. The magnetic effect pigment of claim 1 wherein said metal oxide is an oxide of a metal selected from the group consisting of cobalt, nickel, iron, and manganese.
4. The magnetic effect pigment of claim 1 wherein said ferrite layer comprises cobalt ferrite.
5. The magnetic effect pigment of claim 1 wherein the ferrite layer is formed by calcination at about 700° C. to about 925° C.
6. The magnetic effect pigment of claim 1 wherein the ferrite layer is formed by calcination at about 875° C.
7. The magnetic effect pigment of claim 1 wherein the interference color imparting layer comprises titanium dioxide, iron oxide, zirconium dioxide, zinc oxide, zinc sulfide, bismuth oxychloride, silicon dioxide, magnesium fluoride, or aluminum oxide.
8. The magnetic effect pigment of claim 1 wherein the non-ferrite metal oxide layer comprises titanium dioxide.
9. The magnetic effect pigment of claim 1 wherein said non-ferrite metal oxide layer is formed by calcination at up to about 700° C.
10. The magnetic effect pigment of claim 1 wherein the ferrite is cobalt ferrite and the non-ferrite metal oxide is titanium dioxide.
11. The magnetic effect pigment of claim 1 wherein the substrate is mica, glass flake, SiO 2 , Al 2 O 3 , bismuth oxychloride, or boron nitride.
12. The magnetic effect pigment of claim 1 wherein the substrate is natural mica.
13. The magnetic effect pigment of claim 1 wherein said substrate is synthetic mica.
14. The magnetic effect pigment of claim 1 wherein the substrate is platy.
15. The magnetic effect pigment of claim 1 further comprising an agent to improve weatherabilty of the pigment.
16. The magnetic effect pigment of claim 1 further comprising a metal oxide and silane coupling agent applied onto said metal oxide layer so as to improve weatherabilty of the pigment.
17. The magnetic effect pigment of claim 1 further containing an additional metal oxide layer deposited on the metal oxide layer of the pigment.
18. The magnetic effect pigment of claim 1 further containing a ferrite layer deposited on the non-ferrite metal oxide layer of the pigment.
19. A three-dimensional effect product containing the pigment of claim 1 .
20. A method of creating a magnetic pigment comprising the steps of:
(a) providing a substrate;
(b) coating a ferrite layer on the substrate; and
(c) coating an interference color imparting layer containing a non-ferrite metal oxide on the ferrite layer, said non-ferrite metal oxide being formed by calcination at up to about 700° C.
21. The method of claim 20 , wherein the ferrite layer is formed by calcination at about 825° C. to about 900° C.