Transparent goniochromatic multilayer effect pigment
A multilayer effect pigment includes a transparent substrate, a layer of high refractive index material on the substrate, and alternating layers of low refractive index and high refractive index materials on the first layer, the total number of layers being an odd number of at least three, all adjacent layers differing in refractive index by at least about 0.2 and at least one of the layers having an optical thickness which is different from all of the other layers. The resulting multilayer effect pigment is not a quarter-wave stack. The present effect pigments may be used in cosmetic and industrial applications.
1. A multilayer effect pigment comprising:
a transparent substrate having a layer of titanium dioxide thereon, the optical thickness of said first layer of titanium dioxide being such as to provide a white hue to said substrate;
a layer of a low refractive index material on said titanium dioxide layer and an outermost layer of a high refractive index material placed on said low refractive index material layer;
said outermost layer comprising titanium dioxide having a optical thickness of from about 45 to 240 nm, said low refractive index material layer having an optical thickness of at least 150 nm to provide a variable pathlength for light dependent on the angle of incidence of light impinging thereon;
each layer differs in refractive index from any adjacent layer by at least about 0.2 and wherein at least one layer has an optical thickness which is different from all of the other layers, whereby the pigment is not a quarter-wave stack;
said multilayer effect pigment having a non-white hue, and wherein the pigment has a chromaticity of at least 40.0.
2. The multilayer effect pigment of claim 1 wherein said transparent substrate is glass flake.
3. The multilayer effect pigment of claim 1 in which the low refractive index material is silicon dioxide.
4. The multilayer effect pigment of claim 3 in which the optical thickness of said inner layer of titanium dioxide is about 134±12 nm.
5. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 219±8 nm and said outermost layer has an optical thickness of 95±12 nm and said pigment has a normal gold hue.
6. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 263±8 nm and said outermost layer has an optical thickness of 48±12 nm and said pigment has a normal gold hue.
7. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 219±8 nm and said outermost layer has an optical thickness of 177±12 nm and said pigment has a normal red hue.
8. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 467±8 nm and said outermost layer has an optical thickness of 215±12 nm and said pigment has a normal red hue.
9. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 292±8 nm and said outermost layer has an optical thickness of 95±12 nm and said pigment has a normal violet hue.
10. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 307 to 329±8 nm and said outermost layer has an optical thickness of 48±12 nm or 72±12 nm and said pigment has a normal violet hue.
11. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 329 to 336±8 nm and said outermost layer has an optical thickness of 84±12 nm or 95±12 nm and said pigment has a normal blue hue.
12. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 350 to 365±8 nm and said outermost layer has an optical thickness of 50±12 nm or 67±12 nm and said pigment has a normal blue hue.
13. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 329±8 nm and said outermost layer has an optical thickness of 129±12 nm and said pigment has a normal turquoise hue.
14. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 350 to 365±8 nm and said outermost layer has an optical thickness of 16±12 nm or 95±12 nm and said pigment has a normal turquoise hue.
15. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 380±8 nm and said outermost layer has an optical thickness of 60±12 nm and said pigment has a normal turquoise hue.
16. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 277 to 307±8 nm and said outermost layer has an optical thickness of 198 to 210±12 nm and said pigment has a normal green hue.
17. The multilayer effect pigment of claim 4 wherein the optical thickness of said silicon dioxide layer is 329±8 nm and said outermost layer has an optical thickness of 179±12 nm and said pigment has a normal green hue.
18. In a paint or ink composition including a pigment, the improvement which comprises said pigment being the effect pigment of claim 1 .
19. In a plastic composition including a pigment, the improvement Which comprises said pigment being the effect pigment of claim 1 .
20. In a cosmetic composition including a pigment, the improvement which comprises said pigment being the effect pigment of claim 1 .
21. The multilayer effect pigment of claim 1 wherein the pigment has a chromaticity of at least 50.0.