Method of preparing an anisotropic polymer film on a substrate with a structured surface

• US 20050118355A1
• Filed: 12/10/2004
• Published: 06/02/2005
• Est. Priority Date: 02/13/2002
• Status: Active Grant

• Current Assignee: Allan Marshall Hawkhurst, Guy Gregory, John Patrick, Matthias Kuntz, Peter Howarth, Robert Hammond-Smith, Rodney Riddle, Tony Bleasdale
• Original Assignee: Allan Marshall Hawkhurst, Guy Gregory, John Patrick, Matthias Kuntz, Peter Howarth, Robert Hammond-Smith, Rodney Riddle, Tony Bleasdale
• Inventors: Hawkhurst, Allan Marshall, Patrick, John, Kuntz, Matthias, Riddle, Rodney, Hammond-Smith, Robert, Gregory, Guy, Howarth, Peter, Bleasdale, Tony
• Granted Patent: US 7,083,834 B2
• Time in Patent Office: Days
• US Class Current: 428/1.100
• CPC Class Codes: B42D 2033/26 Liquid-crystal material
• CPC Class Codes: B42D 2035/24 Colours
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: B42D 25/364 Liquid crystals
• CPC Class Codes: B42D 25/425 by deformation, e.g. embossing
• CPC Class Codes: B44F 1/10 Changing, amusing, or secret pictures
• 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 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: C09K 2323/03 Viewing layer characterised by chemical composition
• CPC Class Codes: C09K 2323/031 Polarizer or dye
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: Y10S 428/916 Fraud or tamper detecting

Abstract

An anisotropic polymer film with improved alignments prepared by coating onto a substrate with a structured surface. The polymer films thereby obtained are useful in optical and electrooptical devices for decorative and security applications.

Claims

1. A security marking or device comprising an anisotropic polymer film obtainable by a process comprising:

coating a polymerizable liquid crystalline or mesogenic material onto a substrate with a structured surface,

aligning the polymerizable liquid crystalline or mesogenic material,

polymerizing the polymerizable liquid crystalline or mesogenic material, and

optionally removing the polymerized film from the substrate.

2. A security marking or device according to claim 1, wherein the substrate surface comprises an area of fine grooves or grating, by which the molecules of said polymerizable liquid crystal material are homogeneously aligned with their molecular long axes substantially parallel to the substrate surface and substantially parallel to the direction of said fine grooves or grating.

3. A security marking or device according to claim 2, wherein the direction of the fine grooves or grating is substantially the same over the entire substrate.

4. A security marking or device according to claim 2, wherein the substrate comprises at least two areas having different direction of the fine grooves or grating.

5. A security marking or device according to claim 2, wherein said grooves or grating have a width of 0.2 to 2.0 μ

m and a depth of 0.05 to 0.6 μ

m.

6. A security marking or device according to claim 3, wherein said grooves or grating have a width of 0.2 to 2.0 μ

m and a depth of 0.05 to 0.6 μ

m.

7. A security marking or device according to claim 4, wherein said grooves or grating have a width of 0.2 to 2.0 μ

m and a depth of 0.05 to 0.6 μ

m.

8. A security marking or device according to claim 2, wherein said grooves or grating have a symmetrical profile.

9. A security marking or device according to claim 2, wherein said grooves or grating have an asymmetrical profile.

10. A security marking or device according to claim 2, wherein said grooves or grating have a profile that is rectangular, square, saw tooth, triangular, trapezoidal, sine wave or an approximation to these profiles.

11. A security marking or device according to claim 1, wherein the substrate comprises a carrier layer.

12. A security marking or device according to claim 11, wherein the substrate comprises one or more additional layers on the carrier layer.

13. A security marking or device according to claim 1, wherein the structured surface of said substrate is formed by applying heat and pressure in combination with micro-engraved shims to the substrate.

14. A security marking or device according to claim 1, wherein the structured surface of said substrate is formed by interferography, photolithography, embossing, ion beam etching, electron beam etching, ruling or cast curing.

25. A security marking or device according to claim 1, wherein a reflective layer is applied onto the upper surface of the liquid crystal layer.

26. A security marking or device according to claim 25, wherein the reflective layer is a metal or metallized film, or a metal layer that is deposited on the liquid crystal layer.

15. An anisotropic polymer film with planar alignment obtained by a a process comprising:

coating a polymerizable liquid crystalline or mesogenic material onto a substrate with a structured surface,

aligning the polymerizable liquid crystalline or mesogenic material,

polymerizing the polymerizable liquid crystalline or mesogenic material, and

optionally removing the polymerized film from the substrate.

20. In a security marking or device comprising an anisotropic polymer film, the improvement wherein said film is according to claim 15.

21. In a hot stamping foil, laminate, label, data carrier, document of value, ID or credit card, banknote, security thread, cheque or CD comprising a security marking or device, the improvement wherein said security marking or device is according to claim 20.

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

22. A security marking or device comprising an anisotropic polymer film obtainable by a aligning a liquid crystalline or mesogenic material in a continuous coating process on a conveying substrate comprising orienting the molecular long axes of the molecules of the liquid crystalline or mesogenic material to be substantially parallel to the plane of the substrate and at any desired angle to the substrate moving direction by using a substrate with a structured surface.

23. A security marking or device according to claim 22, wherein the film is embossed and is prepared on a carrier.

24. A security marking or device according to claim 22, wherein the film is embossed and is a hot stamping foil or a part of a hot stamping foil.