Multilayer reflective film or pigment with viewing angle dependent reflection characteristics

• US 6,641,874 B2
• Filed: 03/02/2001
• Issued: 11/04/2003
• Est. Priority Date: 03/02/2000
• Status: Expired due to Fees

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Coates, David, Kuntz, Matthias, Riddle, Rodney, Brueckner, Hans-Dieter
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): Koppikar, Vivek
• Application Number:
  US09/796,732
• Publication Number:
  US 20020022093A1
• Time in Patent Office: 977 Days
• Field of Search: 428/29, 428/1.1, 428/1.31, 428/199, 359/493, 359/497, 252/299.01, 252/582
• US Class Current: 428/29
• CPC Class Codes: C09B 67/0098 Organic pigments exhibiting interference colours, e.g. nacrous pigments
• CPC Class Codes: C09D 5/36 Pearl essence, e.g. coatings containing platelet-like pigments for pearl lustre
• CPC Class Codes: C09K 19/00 Liquid crystal materials
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/031 Polarizer or dye
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: Y10T 428/24835 including developable image or soluble portion in coating or impregnation [e.g., safety paper, etc.]

Abstract

The invention relates to multilayer reflective films and pigments showing selective reflection of light wherein the reflection characteristics are dependent on the viewing angle, characterized in that they comprises at least one reflective layer, at least one circular polarizing layer and optionally at least one optical retardation layer. The invention further relates to the use of these multilayer reflective films and pigments in optical elements, as coatings or in lacquers, inks or paints for cosmetic, decorative or security applications, to inks and paints comprising one or more multilayer reflective pigments dispersed in a light transmissive binder, and to security markings or devices comprising one or more multilayer reflective films or pigments.

Claims

1. A multilayer reflective film or multilayer reflective pigment comprising at least one reflective layer and at least one circular polarizing layer, said circular polarizing layer comprising a linear polarizing layer and a quarter wave retardation layer, wherein said linear polarizing layer comprises a vitrified, polymerized or crosslinked liquid crystal material with planar orientation and/or said quarter wave retardation layer comprises a vitrified, polymerized or crosslinked liquid crystal material with planar or tilted orientation, and whereby said film or pigment selectively reflects light dependent on the viewing angle.

2. The multilayer reflective film or pigment according to claim 1, further comprising at least one optical retardation layer.

3. The multilayer reflective film or pigment according to claim 1, wherein the linear polarizing layer comprises a vitrified, polymerized or crosslinked liquid crystal material with planar or tilted orientation.

4. The multilayer reflective film or pigment according to claim 3, wherein the quarter wave retardation layer comprise a vitrified, polymerized or crosslinked liquid crystal material with planar or tilted orientation.

5. The multilayer reflective film or pigment according to claim 1, comprising a central reflective layer, at least one circular polarizing layer and at least one optical retardation layer on each side of the reflective layer, wherein the circular polarizing layer is outside the retardation layer.

6. The multilayer reflective film or pigment according to claim 1, wherein the reflective layer is a metal layer.

7. The multilayer reflective film or pigment according to claim 1, wherein the reflective layer is a holographic reflective layer.

8. The multilayer reflective pigment according to claim 1, wherein the reflective layer is an interference pigment.

9. The multilayer reflective film according to claim 1, wherein the reflective layer comprises at least one interference pigment.

10. The multilayer reflective film according to claim 9, wherein the reflective layer additionally comprises at least one further pigment or dye.

11. The multilayer reflective film according to claim 6, wherein the metal layer is an automobile body or household object.

12. A platelet shaped pigment obtainable by grinding a multilayer reflective film according to claim 1.

13. A multilayer pigment according to claim 1, obtainable by coating at least one circular polarizing layer and optionally at least one optical retardation layer onto a platelet shaped reflective substrate.

14. An optical element, in a coating, lacquer, ink or paint for cosmetic, decorative or security applications, said element being a multilayer reflective film or pigment according to claim 1.

15. An ink or paint comprising at least one multilayer reflective pigment according to claim 1, dispersed in a light transmissive binder.

16. A security marking or device comprising at least one multilayer reflective film or pigment according to claim 1.

17. An automobile body or metal household object coated with at least one multilayer reflective film or pigment according to claim 1.

18. The multilayer reflective film or pigment according to claim 1, wherein the linear polarizer comprises an uniaxially stretched polymer film or a polymer film into which is incorporated a dichroic dye comprising an uniaxially stretched polymer film of polyvinyl alcohol, or comprising a polymer film into which is incorporated a dichroic dye.

19. The multilayer reflective film or pigment according to claim 1, wherein the quarter wave retardation layer is a stretched or compressed film of isotropic polymer retardation layer, and wherein the quarter wave retardation layer is a stretched or compressed film of isotropic polymer.

20. The multilayer reflective film or pigment according to claim 1, wherein the linear polarizer and/or the quarter wave retardation layer comprise a vitrified, polymerized or crosslinked liquid crystal material with macroscopically uniform orientation, having mesogenic groups of the liquid crystal material being oriented substantially parallel to the plane of the layer into a preferred direction.