Security pigment

Patent metadata

Field	Value
Publication number	US-12152152-B2
Application number	US-202016894517-A
Country	US
Kind code	B2
Filing date	Jun 5, 2020
Priority date	Jun 5, 2020
Publication date	Nov 26, 2024
Grant date	Nov 26, 2024

Abstract

A flake including a layer of a diamagnetic material; and at least one additional layer is disclosed. The flake, such as a plurality of flakes, can be dispersed in a liquid medium to form a composition. The composition can be applied to a surface of a substrate to form a security device. A method of making the security device is also disclosed.

First claim

What is claimed is:

1. A flake, comprising:
a layer of a diamagnetic material;
a reflector layer in contact with a first surface of the layer of the diamagnetic material; and
at least two additional layers including a dielectric layer and an absorber layer, the dielectric layer being in contact with the reflector layer and the absorber layer being in contact with the dielectric layer,
wherein the diamagnetic material has a volume magnetic susceptibility ranging from −2.00×10 6 to −300.0×10 6 .

2. The flake of claim 1 , wherein the diamagnetic material is bismuth.

3. The flake of claim 1 , wherein the diamagnetic material has a volume magnetic susceptibility ranging from −10.00×10 6 to −285.0×10 6 .

4. The flake of claim 1 , wherein the layer of the diamagnetic material has a physical thickness ranging from 950 nm to 2000 nm.

5. The flake of claim 1 , wherein the at least two additional layers include a second reflector layer, a second absorber layer, and a second dielectric layer.

6. The flake of claim 1 , wherein the flake is symmetric.

7. The flake of claim 1 , wherein the flake is asymmetric.

8. The flake of claim 1 , wherein the layer of a diamagnetic material is a central layer in the flake.

9. A composition, comprising:
a plurality of flakes of claim 1 dispersed in a liquid medium.

10. A security device, comprising:
a substrate; and
the composition of claim 9 applied to a surface of the substrate.

11. The security device of claim 10 , wherein the substrate is polyethylene terephthalate, glass foil, glass sheets, polymeric foils, polymeric sheets, metal foils, metal sheets, ceramic foils, ceramic sheets, ionic liquid, paper, silicon wafers.

12. A method of making a security device, comprising:
dispersing, in a liquid medium, a flake including a layer of a diamagnetic material, a reflector layer in contact with a first surface of the layer of the diamagnetic material, and at least two additional layers including a dielectric layer and an absorber layer, the dielectric layer being in contact with the reflector layer and the absorber layer being in contact with the dielectric layer, to form a composition;
applying the composition to a substrate to form a security device;
applying a magnetic field to the security device so that a plane of the flakes align perpendicular to the magnetic field; and
curing the aligned flakes perpendicular to the magnetic field.

13. The method of claim 12 , wherein application of the magnetic field is for a period of time greater than 10 seconds.

14. The method of claim 12 , wherein application of the magnetic field is from a magnet having a maximum energy product greater than 3.5.

15. The method of claim 12 , wherein the cured, aligned flakes form opaque regions on the substrate.

Assignees

• Viavi Solutions Inc

Inventors

• Raksha Vladimir P
• Delst Cornelis Jan

Classifications

• C09D11/037 Primary

  characterised by the pigment · CPC title

• C09C2200/301

  Thickness of the core · CPC title

• C09C2200/24

  Interference pigments comprising a metallic reflector or absorber layer, which is not adjacent to the core · CPC title

• C09C2200/1054

  the core consisting of a metal · CPC title

• C01P2006/42

  Magnetic properties · CPC title