Methods of fabricating color shifting thin film pigments

• US 6,246,523 B1
• Filed: 03/02/2000
• Issued: 06/12/2001
• Est. Priority Date: 11/24/1998
• Status: Expired due to Term

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Flex Products Incorporated (Sicpa Holding SA)
• Inventors: Witzman, Matthew R., Bradley, Richard A. Jr.
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Juba, Jr., John
• Application Number:
  US09/517,148
• Time in Patent Office: 467 Days
• Field of Search: 428/403, 428/404, 106/415, 106/401, 359/585, 359/900, 359/586, 359/588, 359/589
• US Class Current: 359/585
• CPC Class Codes: C01P 2006/62 L* (lightness axis)
• CPC Class Codes: C01P 2006/63 a* (red-green axis)
• CPC Class Codes: C01P 2006/64 b* (yellow-blue axis)
• 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 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 2200/1054 the core consisting of a metal
• CPC Class Codes: C09C 2200/301 Thickness of the core
• CPC Class Codes: C09C 2200/302 Thickness of a layer with high refractive material
• CPC Class Codes: C09C 2200/306 Thickness of an absorbing layer
• CPC Class Codes: C09C 2220/20 PVD, CVD methods or coating in a gas-phase using a fluidized bed
• CPC Class Codes: C09D 5/36 Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361
• CPC Class Codes: Y10S 359/90 Methods
• 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

Methods for fabricating a color shifting multilayer interference film are provided. The interference film may be used to produce flakes for use in colorants having color shifting properties. The flakes can be interspersed into liquid media such as paints or inks which can subsequently be applied to objects or papers to achieve color variations upon shifts in angle of incident light or upon shifts in viewing angle. A five layer design of the interference film includes a first absorber layer, a first dielectric layer on the first absorber layer, a reflector layer on the first dielectric layer, a second dielectric layer on the reflector layer, and a second absorber layer on the second dielectric layer. The first and second dielectric layers are formed to have an optical thickness at a design wavelength that provides a color shift as the angle of incident light or viewing changes.

Claims

1. A method of fabricating a color shifting multilayer interference film, comprising the steps of:

providing a web material with a release layer formed on an upper surface thereof;

forming a first absorber layer on the release layer;

forming a first dielectric layer on the first absorber layer;

forming a reflector layer on the first dielectric layer;

forming a second dielectric layer on the reflector layer;

forming a second absorber layer on the second dielectric layer to produce the interference film; and

removing the interference film from the web material;

wherein the first and second dielectric layers have an index of refraction of greater than 1.65 and an optical thickness at a design wavelength that provides a discrete color shift such that the film has a first color at a first angle of incident light or viewing and a second color different from the first color at a second angle of incident light or viewing.

2. The method of claim 1, wherein the first and second dielectric layers are composed of the same material.

3. The method of claim 1, wherein the first and second dielectric layers have an index of refraction of about 2 or greater.

4. The method of claim 1, wherein the first and second dielectric layers are formed of a material selected from the group consisting of zinc sulfide, zirconium oxide, tantalum oxide, silicon monoxide, cerium oxide, hafnium oxide, titanium oxide, praseodymium oxide, yttrium oxide, and combinations thereof.

5. The method of claim 1, wherein the first and second dielectric layers are formed to have an optical thickness in a range from about 2 QWOT at a design wavelength of about 400 nm to about 9 QWOT at a design wavelength of about 700 nm.

6. The method of claim 1, wherein the first and second dielectric layers have the same optical thickness.

7. The method of claim 1, wherein the first and second absorber layers are formed of a material selected from the group consisting of chromium, nickel, palladium, titanium, vanadium, cobalt, iron, tungsten, molybdenum, niobium, ferric oxide, and combinations or alloys thereof.

8. The method of claim 1, wherein the first and second absorber layers are formed to have a physical thickness of about 50 Å

to about 150 Å

.

9. The method of claim 1, wherein the first and second absorber layers have the same physical thickness.

10. The method of claim 1, wherein the reflector layer is formed of a reflective metal selected from the group consisting of aluminum, silver, copper, gold, platinum, tin, and combinations or alloys thereof.

11. The method of claim 1, wherein the reflector layer is formed to have a physical thickness of about 500 Å

to about 1000 Å

.

12. The method of claim 1, wherein the absorber layers, the dielectric layers, and the reflector layer are each formed by physical vapor deposition.

13. The method of claim 1, wherein the interference film is removed from the web material in the form of a plurality of color shifting flakes.

14. A method of fabricating a color shifting multilayer interference film, comprising the steps of:

providing a web material with a release layer formed on an upper surface thereof;

forming a first absorber layer on the release layer;

forming a dielectric layer on the first absorber layer;

forming a second absorber layer on the dielectric layer to produce the interference film; and

removing the interference film from the web materials

wherein the dielectric layer has an index of refraction of greater than 1.65 and an optical thickness at a design wavelength that provides a discrete color shift such that the film has a first color at a first angle of incident light or viewing and a second color different from the first color at a second angle of incident light or viewing.

15. The method of claim 14, wherein the first and second absorber layers are composed of the same material.

16. The method of claim 14, wherein the first and second absorber layers are formed of a material selected from the group consisting of chromium, nickel, palladium, titanium, vanadium, cobalt, iron, tungsten, molybdenum, niobium, ferric oxide, and combinations or alloys thereof.

17. The method of claim 14, wherein the dielectric layer is formed of a material selected from the group consisting of zinc sulfide, zirconium oxide, tantalum oxide, silicon monoxide, cerium oxide, hafnium oxide, titanium oxide, praseodymium oxide, yttrium oxide, and combinations thereof.

18. The method of claim 14, wherein the dielectric layer is formed to have an optical thickness in a range from about 2 QWOT at a design wavelength of about 400 nm to about 9 QWOT at a design wavelength of about 700 nm.

19. The method of claim 14, wherein the absorber layers and the dielectric layer are each formed by physical vapor deposition.

20. The method of claim 14, wherein the interference film is removed from the web material in the form of a plurality of color shifting flakes.