| US 7,374,609 B2 | ||
| Optically variable pigments having an asymmetrical layer structure | ||
| Patrice Bujard, Reinach (Switzerland); and Philippe Bugnon, Le Mouret (Switzerland) | ||
| Assigned to Ciba Specialty Chemicals Corporation, Tarrytown, N.Y. (US) | ||
| Appl. No. 10/533,575 PCT Filed Nov. 12, 2003, PCT No. PCT/EP03/50817 § 371(c)(1), (2), (4) Date May 03, 2005, PCT Pub. No. WO2004/046254, PCT Pub. Date Jun. 03, 2004. |
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| Claims priority of application No. 02406007 (EP), filed on Nov. 21, 2002. | ||
| Prior Publication US 2006/0027139 A1, Feb. 09, 2006 | ||
| Int. Cl. C09D 11/00 (2006.01) | ||
| U.S. Cl. 106—31.65 [106/400; 106/481; 106/482; 106/415; 106/404; 257/77] | 14 Claims |
| 1. A platelet-like pigment whose particles have a length of from 2 μm to 5 mm, a width of from 2 μm to 2 mm and a thickness
of from 50 nm to 1.5 μm and a ratio of length to thickness of at least 2:1, the particles having a core of a metallically
reflecting material having two substantially parallel faces, the distance between which is the shortest axis of the core,
comprising
(a) on one parallel face of the core, an SiOy layer wherein 0.95<y≤2.0, wherein the thickness of the SiOy layer (a) is from 20 to 500 nm
(b) on the SiOy layer, an SiOx layer wherein 0.03≤x≤0.95, and
(c) on the SiOx layer, an SiOz layer, wherein 0.95<z≤2.0
wherein the metallically reflecting material is selected from Ag, Al, Au, Cu, Cr, Ge, Mo, Ni, Ti, Zn, alloys thereof, graphite,
Fe2O3 and MoS2 and the thickness of the core is from 20 to 100 nm.
|