Cholesteric liquid crystal optical bodies and methods of manufacture and use

• US 6,876,427 B2
• Filed: 09/21/2001
• Issued: 04/05/2005
• Est. Priority Date: 09/21/2001
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ebihara, Ikuko, Bowley, Christopher C., Gilligan, Gregory Edward, Rao, Prabhakara Satyauolu, Radcliffe, Marc Dudley, Pokorny, Richard John, Watson, Philip Edwin
• Primary Examiner(s): Parker, Kenneth
• Assistant Examiner(s): CHUNG, DAVID Y
• Application Number:
  US09/957,724
• Publication Number:
  US 20030063245A1
• Time in Patent Office: 1,292 Days
• Field of Search: 349/175, 349/185, 349/115, 349/98, 349/86, 252/299.01
• US Class Current: 349/185
• CPC Class Codes: C09K 19/02 characterised by optical, electrical or physical properties of the components, in general
• CPC Class Codes: C09K 19/42 Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40
• CPC Class Codes: C09K 19/586 Optically active dopants; chiral dopants
• 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 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers

Abstract

An optical body includes a) first particles comprising a first cholesteric liquid crystal material and b) a second cholesteric liquid crystal material. The first particles and the second cholesteric liquid crystal material form a structure where the first cholesteric liquid crystal material has a pitch that is different than the second cholesteric liquid crystal material. In one example, the second cholesteric liquid crystal material is in the form of second particles. In another example, the first particles are dispersed in a matrix of the second cholesteric liquid crystal material. In other examples, the optical body has more than one layer. In addition, one or more additional cholesteric liquid crystal materials can be used in the optical body. These optical bodies can be used as a reflective polarizer and can be used in a display.

Claims

1. An optical body, comprising:

(a) a plurality of first particles comprising a first cholesteric liquid crystal material; and

(b) a second cholesteric liquid crystal material fomiing a structure with the plurality of first particles, and in contact with the first cholesteric liquid crystal material wherein the first cholosteric liquid crstal material has a pitch that is different than the second cholesteric liquid crystal material;

wherein, the particles of the first cholesteric liquid crystal material are partially diffused with the second cholesteric liquid crystal material forming a region having a pitch intermediate between the first cholesteric liquid crystal material pitch and the second cholesteric liquid crystal material pitch.

2. The optical body of claim 1, wherein the first particles have an average diameter in the range of 0.5 μ

m to 5 μ

m.

3. The optical body of claim 1, wherein the second cholesteric liquid crystal material is disposed as a plurality of second particles.

5. The optical body of claim 1, wherein the first cholesteric liquid crystal material comprises a reaction product of first chiral monomers and first achiral monomers.

6. The optical body of claim 5, wherein the second cholesteric liquid crystal material comprises a reaction product of the first chiral monomers and the first achiral monomers in a different ratio than the first cholesteric liquid crystal material.

7. The optical body of claim 5, wherein the second cholesteric liquid crystal material comprises a reaction product of second chiral monomers and second achiral monomers, wherein the second chiral monomers are different than the first chiral monomers.

8. The optical body of claim 1, wherein the first cholesteric liquid crystal material comprises a reaction product of first chiral monomers, first achiral monomers, and plasticizing monomers.

9. The optical body of claim 1, wherein the stmcture comprises more than one layer.

10. The optical body of claim 9, wherein the first cholesteric liquid crystal material is disposed in a first layer of the structure and the second cholesteno liquid crystal material is disposed in a second layer of the structure.

11. The optical body of claim 1, wherein the optical body reflects light having a spectral width of at least 200 nm.

12. The optical body of claim 1, further comprising a third cholesteric liquid crystal material disposed in the structure, wherein the third cholesteric liquid crystal material has a different pitch than the first and second liquid crystal materials.

13. The optical body of claim 12, wherein the third cholesteric liquid exystal material is disposed as a plurality of third particles.

14. The optical body of claim 13, wherein the second and third cholesteric liquid crystal materials are disposed as a plurality of second and third particles, respectively.

15. The optical body of claim 14, wherein the first and third particles are dispersed in a matrix comprising the second cholesteric liquid crystal material.

16. The optical body of claim 1, wherein at least one of the first and second cholesteric liquid crystal materials is a polymer comprising surfactant comonomer units.

4. An optical body, cornrrising:

(a) a plurality of first particles comprising a first cholesteric liquid crystal material; and

(b) a second cholesteric liquid crystal material forming a structure with the plurality of first particles, and in contact with the first cholesteric liquid crystal material wherein the first cholesteric liquid crystal material has a pitch that is different than the second cholesteric liquid crystal material, wherein the plurality of first particles are dispersed in a matrix comprising the second cholesterie liquid crystal material.

17. A reflective polarizer comprising:

(a) a plurality of first particles comprising a first cholesteric liquid crystal material; and

(b) a second cholesteric liquid crystal material forming a structure with the plurality of first particles and in contact with the first cholestric liquid crystal material, wherein the first cholesteric liquid crystal material has a pitch that is different than the second cholesteric liquid crystal material;

wherein, the particles of the first cholesteric liquid crystal material are partially diffused with the second cholesteric liquid crystal material forming a region having a pitch intermediate between the first cholesteric liquid crystal material pitch and the second cholesteric liquid crystal material pitch.

18. An optical display, comprising:

a reflective polarizer comprising

(a) a plurality of first particles comprising a first cholesteric liquid crystal material; and

(b) a second cholesteric liquid crystal material forming a structure with the plurality of first particles and in contact with the first cholestric liquid crystal material, wherein the first cholesteric liquid crystal material has a pitch that is different than the second cholesteric liquid crystal material;

wherein, the particles of the first cholesteric liquid crystal material are partially diffused with the second cholesteric liquid crystal material forming a region having a pitch intermediate between the first cholesteric liquid crystal material pitch and the second cholesteric liquid crystal material pitch.

19. The optical display of claim 18, further comprising a light source.

20. An optical body, comprising:

(a) a plurality of first particles comprising a first cholesteric liquid crystal material; and

(b) a second cholesteric liquid material forming a matrix with the plurality of first particles dispersed therein, wherein the first cholesteric liquid crystal material has a pitch that is different that the second cholesteric liquid crystal material.

21. The optical body of claim 20, wherein the first cholesteric liquid crystal material comprises a reaction product of first chiral monomers and first achiral monomers.

22. The optical body of claim 21, wherein the second cholesteric liquid crystal material comprises a reaction product of the firs chiral monomers and the first chiral monomers in a different ratio that the first cholesteric liquid crystal monomers.

23. The opticalbody of claim 21, wherein the second cholersitc liquid crystal material comprises a reaction product of second chiral monomers and second achiral monomers, wherein the second chiral monomers are different than the first chiral monomers.

24. The optical body of claim 20, wherein the first cholersitic liquid crystal material comprises a reaction product of first chiral monomers, first achiral monomers, and plasticizing monomers.

25. The optical body of claim 20, wherein the optical body reflects light having a spectral width of ar least 200 nm.

26. The optical body of claim 20, wherein the particles of the first choleristic liquid crystal material are partially diffused with the second choleristic liquid crystal material.

27. The optical body of claim 20, further comprising a third choleric liquid crystal material disposed in the structure, wherein the third cholestric liquid crystal material has a different pitch than the first and second liquid crystal materials.

28. The optical body of claim 20, wherein the third cholesteric liquid crystal material is disposed as a plurality of third particles.

29. The optical body of claim 20, wherein at least on of the first and second cholesteric liquid crystal materials is a polymer comprising surfactant comonomer units.

30. A reflective polarizer comprising the optical body of claim 20.

31. An optical display comprising the reflective polarizer of claim 30.