Surface Treated Flake
The instant invention provides an asymmetrical orientable flake for use in a carrier. The flake includes a metal reflector layer and a coating of a carrier-repellent material coated on a single side of the flake, for orienting the flake in the carrier so that the flake rests upon the carrier having a first side at least partially out of the carrier and a second side immersed in the carrier. The flake has an asymmetrical feature, such as a color shifting coating on a single surface of the reflector layer. Alternatively, the asymmetrical feature is either a relief symbol or an asymmetrical profile of the flake.
1 . An asymmetrical reflective flake having a first side and a second side, for use in a carrier, comprising:
a metal reflector layer, for reflecting light; and
a coating of a material repellent to the carrier, supported by the metal reflector layer, wherein the material repellent to the carrier is coated on the first side of the flake, for self-assembling the flake in the carrier so that the flake rests upon the carrier having the first side at least partially out of the carrier and the second side immersed in the carrier, and wherein the second side of the flake is absent any carrier-repellent material.
2 . A flake as defined in claim 1 , wherein a first surface of the metal reflector layer is a concave surface having a depression of at least 20 nm, and a second surface of the metal reflector layer, opposite to the first surface, is a convex surface.
3 . A flake as defined in claim 2 , wherein the depression has an average radius of curvature greater than 2 microns and less than 6 mm.
4 . A flake as defined in claim 2 , wherein the first surface of the metal reflector layer has a flat region adjacent to the depression.
5 . A flake as defined in claim 1 further comprising a dielectric layer on a first surface of the metal reflector layer, and a coating of an absorber material on the dielectric layer, for providing a color shifting effect on the first side of the flake.
6 . A flake as defined in claim 5 , wherein a second surface of the metal reflector layer, opposite to the first surface of the metal reflector layer, is absent at least the absorber material, whereby the second side of the flake is absent the color shifting effect.
7 . A flake as defined in claim 1 having a relief symbol on a first surface of the metal reflector layer, and not having the relief symbol in a second surface of the metal reflector layer, opposite to the first surface of the metal reflector layer.
8 . A coating comprising a carrier and a plurality of flakes, each having a structure defined in claim 1 , wherein at least 70% of the flakes rest upon the carrier having the first side up.
9 . A method of manufacturing a plurality of flakes defined in claim 1 , comprising the steps of:
(a) providing a substrate;
(b) depositing a first layer over the substrate, wherein the first layer is one of the metal reflector layer and the coating of the material repellent to the carrier;
(c) depositing a second layer over the first layer, wherein the second layer is another of the metal reflector layer and the coating of the material repellent to the carrier; and,
(d) separating the plurality of flakes from the substrate.
10 . A method as defined in claim 9 , wherein the substrate is a non-flat substrate having trenches forming a frame on the surface thereof and a concave or convex region within the frame.
11 . A method as defined in claim 9 , wherein the substrate is a non-flat substrate having trenches forming a frame on the surface thereof and a relief symbol within the frame.
12 . A method as defined in claim 9 , further comprising a step of depositing a dielectric layer, between steps (b) and (c).
13 . A method as defined in claim 9 , further comprising a step of depositing an absorber layer, after step (b) and before step (c).
14 . A method as defined in claim 9 , further comprising a step of depositing a release layer on the substrate before step (a).