Multi-layered magnetic pigments and foils

• US 6,838,166 B2
• Filed: 08/08/2003
• Issued: 01/04/2005
• Est. Priority Date: 04/27/2001
• Status: Expired due to Term

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Flex Products Incorporated (Sicpa Holding SA)
• Inventors: Mayer, Thomas, Phillips, Roger W., Coombs, Paul G., Markantes, Charles T., LeGallee, Charlotte R.
• Primary Examiner(s): KILIMAN, LESZEK B
• Application Number:
  US10/637,605
• Publication Number:
  US 20040028905A1
• Time in Patent Office: 515 Days
• Field of Search: 428/323, 428/327, 428/328, 428/329, 428/402, 428/403, 428/404
• US Class Current: 428/323
• CPC Class Codes: B41M 3/14 Security printing securities B42D25/29
• CPC Class Codes: B42D 2033/16 Magnetic or magnetisable material
• CPC Class Codes: B42D 2035/24 Colours
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: B42D 25/369 Magnetised or magnetisable materials
• CPC Class Codes: C01P 2004/52 highly monodisperse size distribution
• CPC Class Codes: C01P 2004/54 Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/86 Thin layer coatings, i.e. the coating thickness being less than 0.1 time the particle radius
• CPC Class Codes: C01P 2006/42 Magnetic properties
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: C01P 2006/65 Chroma (C*)
• CPC Class Codes: C01P 2006/66 Hue (H*)
• CPC Class Codes: C01P 2006/90 Other properties not specified above
• CPC Class Codes: C09C 1/0015 Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
• CPC Class Codes: C09C 1/0078 Pigments consisting of flaky, non-metallic substrates, characterised by a surface-region containing free metal
• CPC Class Codes: C09C 1/62 Metallic pigments or fillers C09C1/0015 takes precedence
• CPC Class Codes: C09C 2200/1008 comprising at least one metal layer adjacent to the core material, e.g. core-M or M-core-M
• CPC Class Codes: C09C 2200/1025 comprising at least one metal layer adjacent to core material, e.g. core-M or M-core-M
• CPC Class Codes: C09C 2200/1054 the core consisting of a metal
• CPC Class Codes: C09C 2200/1058 : comprising a protective coating on the metallic layer
• CPC Class Codes: C09C 2200/1091 : comprising at least one metal layer adjacent to the core material, e.g. core-M or M-core-M
• CPC Class Codes: C09C 2200/24 : Interference pigments comprising a metallic reflector or absorber layer, which is not adjacent to the core
• CPC Class Codes: C09C 2200/301 : Thickness of the core
• CPC Class Codes: C09C 2220/20 : PVD, CVD methods or coating in a gas-phase using a fluidized bed
• CPC Class Codes: Y10S 428/90 : Magnetic feature
• CPC Class Codes: Y10T 428/25 : Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/254 : Polymeric or resinous material
• CPC Class Codes: Y10T 428/256 : Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/257 : Iron oxide or aluminum oxide
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2991 : Coated
• CPC Class Codes: Y10T 428/2993 : Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Abstract

Multilayered magnetic pigment flakes and foils are provided. The pigment flakes can have a symmetrical coating structure on opposing sides of a magnetic core, or can be formed with encapsulating coatings around the magnetic core. The magnetic core can be a magnetic layer between reflector or dielectric layers, a dielectric layer between magnetic layers, or only a magnetic layer. Some embodiments of the pigment flakes and foils exhibit a discrete color shift so as to have distinct colors at differing angles of incident light or viewing. The pigment flakes can be interspersed into liquid media such as paints or inks to produce colorant compositions for subsequent application to objects or papers. The foils can be laminated to various objects or can be formed on a carrier substrate.

Claims

1. A magnetic pigment flake, comprising:

a central magnetic layer having a first major surface, an opposing second major surface, and at least one side surface;

a first reflector layer on the first major surface of the magnetic layer; and

a second reflector layer on the second major surface of the magnetic layer;

wherein the pigment flake exhibits a reflectivity corresponding to the reflectivity of the reflector layers and exhibits magnetic characteristics based on the relative magnetism of the magnetic layer.

2. The pigment flake of claim 1, wherein the first and second reflector layers are on each of the first and second major surfaces but not on the at least one side surface of the magnetic layer.

3. The pigment flake of claim 1, wherein the first and second reflector layers form part of a contiguous reflecting layer substantially surrounding the magnetic layer.

4. The pigment flake of claim 1, wherein the magnetic layer comprises a soft magnetic material.

5. The flake of claim 1, wherein the magnetic layer is composed of a material with a coercivity of less than about 2000 Oe.

6. The flake of claim 1, wherein the magnetic layer is composed of a material with a coercivity of less than about 300 Oe.

7. The pigment flake of claim 1, wherein the magnetic layer comprises a material selected from the group consisting of iron, nickel, cobalt, iron, gadolinium, terbium, dysprosium, erbium, and alloys or oxides thereof.

8. The pigment flake of claim 1, wherein the magnetic layer comprises a material selected from the group consisting of Fe/Si, Fe/Ni, FeCo, Fe/Ni/Mo, and combinations thereof.

9. The pigment flake of claim 1, wherein the magnetic layer comprises a hard magnetic material.

10. The pigment flake of claim 1, wherein the magnetic layer comprises a material selected from the group consisting of SmCo₅, NdCo₅, Sm₂Co₁₇, Nd₂Fe₁₄B, TbFe₂, and combinations thereof.

11. The pigment flake of claim 1, wherein the magnetic layer comprises a material selected from the group consisting of Fe₃O₄, NiFe₂O₄, MnFe₂O₄, CoFe₂O₄, YIG, GdIG, and combinations thereof.

12. The pigment flake of claim 1, wherein the magnetic layer has a physical thickness of about 200 Å

to about 10,000 Å

.

13. The pigment flake of claim 1, wherein the reflector layers comprise a reflective material selected from the group consisting of aluminum, silver, copper, gold, platinum, tin, titanium, palladium, nickel, cobalt, rhodium, niobium, chromium, and combinations or alloys thereof.

14. The pigment flake of claim 1, wherein the reflector layers each have a physical thickness of about 400 Å

to about 2,000 Å

.

15. A magnetic colorant composition, comprising:

a pigment medium; and

a plurality of pigment flakes dispersed in the pigment medium, the pigment flakes having a multilayer structure substantially the same as the pigment flake defined in claim 1.

16. The colorant composition of claim 15, wherein the pigment medium comprises a material selected from the group consisting of acrylic melamine, urethanes, polyesters, vinyl resins, acrylates, methyl methacrylate, ABS resins, epoxies, styrenes, ink and paint formulations based on alkyd resins, and mixtures thereof.