Magnetic or magnetisable pigment particles and optical effect layers

Patent metadata

Field	Value
Publication number	US-10279618-B2
Application number	US-201414910091-A
Country	US
Kind code	B2
Filing date	Jul 25, 2014
Priority date	Aug 5, 2013
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

The invention relates to the field of non-spherical magnetic or magnetisable pigment particles and coating compositions comprising those pigment particles for producing optical effect layers (OEL) wherein the magnetic or magnetisable pigment particles are magnetically oriented. In particular, the present invention provides uses of said optical effect layers (OEL) layers as anti-counterfeit means on security documents or security articles. In particular, it relates to the field of non-spherical magnetic or magnetisable pigment particles comprising a magnetic metal selected from the group consisting of cobalt, iron, gadolinium and nickel; a magnetic alloy of iron, manganese, cobalt, nickel, or a mixture of two or more thereof; a magnetic oxide of chromium, manganese, cobalt, iron, nickel or a mixture of two or more thereof; or a mixture of two or more thereof, and having a d50 value higher than 6 μm and lower than 13 μm, their uses in coating compositions comprising a binder material for producing an optical effect layer (OEL), OEL obtained thereof and processes for producing said OEL.

First claim

The invention claimed is:

1. Non-spherical magnetic or magnetizable pigment particles comprising: at least one of:
a magnetic metal selected from the group consisting of cobalt, iron, gadolinium and nickel;
a magnetic alloy of iron, manganese, cobalt, nickel or a mixture of two or more thereof; and
a magnetic oxide of chromium, manganese, cobalt, iron, nickel or a mixture of two or more thereof;
wherein the particles have a d50 value that is higher than 6 μm and lower than 13 μm in combination with a d90 value lower than 20 μm, wherein the d50 and d90 values are determined by circle equivalent diameters as a percent of the cumulative volume of the particles.

2. The non-spherical magnetic or magnetizable pigment particles according to claim 1 , comprising a mixture of at least two of:
the magnetic metal selected from the group consisting of cobalt, iron, gadolinium and nickel;
the magnetic alloy of iron, manganese, cobalt, nickel or a mixture of two or more thereof; and
the magnetic oxide of chromium, manganese, cobalt, iron, nickel or a mixture of two or more thereof.

3. The non-spherical magnetic or magnetizable pigment particles according to claim 1 , wherein the d50 value is between about 7 μm to about 10 μm and the d90 value is lower than 15 μm.

4. The non-spherical magnetic or magnetizable pigment particles according to claim 1 , wherein the d50 value is between about 7 μm to about 10 μm.

5. The non-spherical magnetic or magnetizable pigment particles according to claim 1 , wherein the d90 value is lower than 15 μm.

6. The non-spherical magnetic or magnetizable pigment particles according to claim 1 being platelet-shaped pigment particles.

7. The non-spherical magnetic or magnetizable pigment particles according to claim 1 , wherein at least a part of the non-spherical magnetic or magnetizable pigment particles comprise non-spherical optically variable magnetic or magnetizable pigment particles.

8. The non-spherical magnetic or magnetizable pigment particles according to claim 7 , wherein the non-spherical optically variable magnetic or magnetizable pigment particles are selected from the group consisting of magnetic thin-film interference pigment particles, magnetic cholesteric liquid crystal pigment particles, interference coated pigment particles comprising a magnetic material and mixtures of two or more thereof.

9. The non-spherical magnetic or magnetizable pigment particles according to claim 8 , wherein the magnetic thin-film interference pigment particles comprise a 5-layer Fabry Perot absorber/dielectric/reflector/dielectric/absorber multilayer structure, in which the reflector layer and/or the absorber layer is a magnetic layer comprising nickel, iron and/or cobalt, and/or a magnetic alloy comprising nickel, iron and/or cobalt and/or a magnetic oxide comprising nickel (Ni), iron (Fe) and/or cobalt (Co).

10. The non-spherical magnetic or magnetizable pigment particles according to claim 9 , wherein the dielectric layers are independently made from one or more selected from the group consisting of magnesium fluoride and silicium dioxide.

11. The non-spherical magnetic or magnetizable pigment particles according to claim 8 , wherein the magnetic thin-film interference pigment particles comprise a 7-layer Fabry Perot absorber/dielectric/reflector/magnetic/reflector/dielectric/absorber multilayer structure or a 6-layer Fabry-Perot multilayer absorber/dielectric/reflector/magnetic/dielectric/absorber multilayer structure, and
wherein the magnetic layer comprises nickel, iron and/or cobalt; and/or a magnetic alloy comprising nickel, iron and/or cobalt and/or a magnetic oxide comprising nickel, iron and/or cobalt.

12. The non-spherical magnetic or magnetizable pigment particles according to claim 11 , wherein the reflector layers are independently made from at least one selected from the group consisting of aluminum, chromium, nickel, and alloys thereof; and/or the dielectric layers are independently made from one or more selected from the group consisting of magnesium fluoride and silicium dioxide; and/or the absorber layers are independently made from one or more selected from the group consisting of chromium, nickel and alloys thereof.

13. A use of the non-spherical magnetic or magnetizable pigment particles recited in claim 1 in a coating composition comprising a binder material for producing an optical effect layer (OEL).

14. A coating composition for producing an optical effect layer (OEL), said coating composition comprising the non-spherical magnetic or magnetizable pigment particles recited in claim 1 and a binder material.

15. An optical effect layer (OEL) comprising the coating composition recited in claim 14 in hardened form, wherein the non-spherical magnetic or magnetizable pigment particles are magnetically oriented.

16. An optical effect coated substrate (OEC) comprising:
at least one of the optical effect layer (OEL) recited in claim 15 on a substrate.

17. A method comprising:
one of:
protecting a security document against counterfeiting or fraud by applying the optical effect coated substrate (OEC) recited in claim 16 , or
decorating a further substrate by applying the optical effect coated substrate.

18. A method comprising:
providing at least one of the optical effect layer (OEL) recited in claim 15 on a substrate to one of: protect the substrate, which is formed as a security document, against counterfeiting or fraud; or decorate the substrate.

19. A security document or a decorative element or object comprising one or more optical effect layers (OELs) recited in claim 15 .

20. A process for producing an optical effect layer (OEL) comprising:
a) applying, on a substrate surface or on a supporting surface of a magnetic-field generating device, the coating composition recited in claim 14 , said coating composition being in a first state,
b) exposing the coating composition in a first state to a magnetic field of the magnetic field-generating device, thereby orienting at least a part of the non-spherical magnetic or magnetizable pigment particles, and
c) hardening the coating composition to a second state that fixes the non-spherical magnetic or magnetizable pigment particles in the oriented positions.

21. The process according to claim 20 , wherein the hardening occurs at least partially simultaneously with the exposing of the coating composition to the first magnetic field.

Assignees

• Sicpa Holding Sa

Inventors

• Degott Pierre
• Schmid Mathieu
• Despland Claude-Alain
• Amerasinghe Cédric

Classifications

• C09D5/36

  Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre · CPC title

• C01P2004/20

  extending in two dimensions, e.g. plate-like · CPC title

• B41M3/14

  Security printing {(securities B42D25/29)} · CPC title

• C09C2200/1058

  comprising a protective coating on the metallic layer · CPC title

• B42D25/369 Primary

  Magnetised or magnetisable materials · CPC title