High chroma multilayer interference platelets

• US 5,569,535 A
• Filed: 04/22/1994
• Issued: 10/29/1996
• Est. Priority Date: 12/28/1979
• Status: Expired due to Term

• Current Assignee: JDS Uniphase Corporation (Lumentum Holdings Inc.)
• Original Assignee: Flex Products Incorporated (Sicpa Holding SA)
• Inventors: Fisher, Shari P., Phillips, Roger W., Coombs, Paul G.
• Primary Examiner(s): Thibodeau, Paul J.
• Assistant Examiner(s): Chen, Vivian
• Application Number:
  US08/231,396
• Time in Patent Office: 921 Days
• Field of Search: 106/400, 106/415, 106/403, 106/404, 106/436, 106/425, 106/419, 428/402, 428/403, 428/404, 428/450, 428/457, 428/699, 428/702, 428/701, 428/363, 428/30, 428/31
• US Class Current: 428/403
• CPC Class Codes: B05D 1/286 using a temporary backing to which the coating has been applied
• CPC Class Codes: B05D 5/06 to obtain multicolour or other optical effects B05D5/02 takes precedence
• CPC Class Codes: B29C 70/585 incorporation of light reflecting filler, e.g. lamellae to obtain pearlescent effet partially embedding reflective elements into the surface of or support B29D11/00615
• CPC Class Codes: B41M 3/00 Printing processes to produce particular kinds of printed work, e.g. patterns printing apparatus or machines of special type or for particular purposes B41F17/00; special designs or pictures per se B44F; manufacturing printed circuits using printing techniques H05K3/12 ; manufacturing organic semiconductor devices using printing techniques H10K71/13
• CPC Class Codes: B41M 3/06 Veined printings; Fluorescent printings; Stereoscopic images; Imitated patterns, e.g. tissues, textiles
• CPC Class Codes: B41M 3/14 Security printing securities B42D25/29
• CPC Class Codes: B41M 3/148 Transitory images, i.e. images only visible from certain viewing angles
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: B44F 1/08 characterised by colour effects
• CPC Class Codes: C01P 2004/51 Particles with a specific particle 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 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C03C 17/00 Surface treatment of glass, not in the form of fibres or filaments, by coating optical coatings of optical elements G02B1/10
• 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 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 2200/24 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 2200/303 Thickness of a layer with low 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 11/50 : Sympathetic, colour changing or similar inks
• CPC Class Codes: C09D 5/36 : Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre
• CPC Class Codes: F24S 70/225 : for spectrally selective absorption
• CPC Class Codes: G02B 5/223 : containing organic substances, e.g. dyes, inks or pigments
• 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: G02B 5/286 : having four or fewer layers, e.g. for achieving a colour effect
• CPC Class Codes: Y02B 10/20 : Solar thermal
• CPC Class Codes: Y02E 10/40 : Solar thermal energy, e.g. solar towers
• 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.]
• CPC Class Codes: Y10T 428/31678 : Of metal

Abstract

A collection of color-shifting interference thin film platelets of high chroma characterized in that the platelets are comprised of a metal reflecting layer having first and second surfaces and a multilayer interference thin film structure disposed on both surfaces of the metal reflecting layer. The multilayer interference thin film structure comprises a pair of layers consisting of a dielectric layer and a semi-opaque metal layer with the dielectric layer being directly adjacent to a surface of the metal reflecting layer. The layers of the multilayer interference thin film structure lie in parallel planes. Each platelet has an aspect ratio of at least 2:1, respectively, for surfaces parallel to the planes of layers and surfaces perpendicular to the planes of the layers. The platelets have a maximum dimension on any surface ranging from approximately 2-200 microns.

Claims

1. A collection of color shifting interference thin film platelets which change color as the angle of incident light or viewing changes for use in a medium for producing a color shifting coating, said collection of color shifting interference thin film platelets being characterized in that each platelet has first and second parallel planar outer surfaces and an edge thickness perpendicular to the first and second parallel planar outer surfaces, each of said platelets comprising a metal reflecting layer having first and second reflective surfaces and a multilayer interference thin film structure disposed on each of the first and second reflective surfaces, the multilayer interference thin film structure comprising a pair of layers consisting of a dielectric layer formed of a dielectric material and a semi-opaque metal layer, said pair being disposed so that the dielectric layer is directly adjacent to the metal reflecting layer and the semi-opaque metal layer faces away from the metal reflecting layer, each platelet having an aspect ratio of at least 2:

1 for the longest dimension of the first and second outer surfaces in comparision to the edge thickness of the platelet, each platelet having a maximum dimension on any surface of about 2-200 microns.

2. A collection as in claim 1 wherein the multilayer interference thin film structure on the first reflective surface has layers having the same thickness as the corresponding layers in the multilayer interference thin film structure on the second reflective surface whereby the same color shift is exhibited by the first and second outer surfaces of the platelets.

3. A collection as in claim 1 wherein the multilayer interference thin film structure on the first reflective surface has layers which differ in thicknesses from the corresponding layers in the multilayer interference thin film structure on the second reflective surface whereby different color shifts are exhibited by the first and second outer surfaces of the platelets.

4. A collection as in claim 1 wherein said metal reflecting layer is semi-opaque and has a thickness ranging from 80-350 Å

.

5. A collection as in claim 1 wherein said metal reflecting layer is opaque and has a thickness which is greater than the 350 Å

.

6. A collection as in claim 1 wherein the said dielectric layers in the multilayer interference thin film structure has a thickness of at least two quarter waves at a design wavelength of 400 nanometers.

7. A collection as in claim 1 wherein said dielectric layers in the multilayer interference thin film structure has a maximum thickness of six-quarter wavelengths at a design wavelengths of 700 nanometers.

8. A collection as in claim 1 in combination with at least one additive selected from the group consisting of non-interference pigments, dyes and interference pigments.

9. A collection as in claim 1 wherein said dielectric layers have an index of refraction of n≦

2.0 and a thickness at a design wavelength which provides a color shift as the angle of incident light or the angle of viewing changes.

10. A collection of colored interference thin film platelets for use in a medium for producing color coating, said collection of colored interference thin film platelets being characterized in that each platelet has first and second parallel planar outer surfaces and an edge thickness perpendicular to the first and second parallel planar outer surfaces, each of said platelets comprising a metal reflecting layer having first and second reflective surfaces and a multilayer interference thin film structure disposed on each of the first and second reflective surfaces, the multilayer interference thin film structure comprising a pair of layers consisting of a dielectric layer formed of a dielectric material and a semi-opaque metal layer, said pair being disposed so that the dielectric layer is directly adjacent to the metal reflecting layer and the semi-opaque metal layer faces away from the metal reflecting layer, each platelet having an aspect ratio of at least 2:

1 for the longest dimension of the first and second outer surfaces in comparison to the edge thickness of the platelet, each platelet having a maximum dimension on any surface of about 2-200 microns, said dielectric layer of said multilayer interference thin film structure having an index of refraction of n≧

2.0 and a thickness at a design wavelength which produces a single color which does not shift color as the angle of incident light or the angle of viewing changes.