Encapsulated liquid crystal apparatus with a polymer additive

• US 4,950,052 A
• Filed: 08/29/1988
• Issued: 08/21/1990
• Est. Priority Date: 08/29/1988
• Status: Expired due to Term

• Current Assignee: Raychem Limited (TE Connectivity Limited)
• Original Assignee: Taliq Corp. (Raychem Corporation)
• Inventors: Fergason, James L., Fan, Ning S.
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/237,974
• Time in Patent Office: 722 Days
• Field of Search: 350/334, 350/347 V, 350/351, 252/299.01, 252/308, 252/309, 252/312, 252/351, 252/358, 252/311, 252/299.5, 252/299.6, 428/1, 428/402.2, 428/402.21, 428/402.22, 427/213.3, 427/213.31, 427/213.32, 427/213.33, 427/213.34, 427/213.35, 427/213.36
• US Class Current: 349/92
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: C09K 2323/057 Ester polymer, e.g. polycarbonate, polyacrylate or polyester
• CPC Class Codes: Y10S 516/01 Wetting, emulsifying, dispersing, or stabilizing agents
• CPC Class Codes: Y10T 428/2984 Microcapsule with fluid core [includes liposome]
• CPC Class Codes: Y10T 428/2985 Solid-walled microcapsule from synthetic polymer

Abstract

A liquid crystal apparatus including a latex containment medium, a liquid crystal material dispersed in plural volumes in the medium, and a barrier means forming a wall in plural volumes in said medium so as to preserve the integrity of the volumes of the liquid crystal material.

Claims

1. A liquid crystal apparatus comprising:

a containment medium, a liquid crystal material dispersed in plural volumes in said medium wherein passageways extend between said volumes and to a surface of said medium, and a barrier means forming a wall in plural volumes in said medium and in at least some of said passageways to preserve the integrity of said volumes.

2. The apparatus of claim 1 wherein said medium is a latex and said barrier means is a water soluble polymer.

3. The apparatus of claim 2 wherein said barrier means and said liquid crystal materia have solubility parameters that differ by at least two Hildebrand units.

4. The apparatus of claim 2 wherein said barrier means is formed from polyvinylpyrrolidone.

5. The apparatus of claim 2 wherein the amount of said water soluble polymer in said apparatus is about 0.5% to 30% of the weight of said medium.

6. The apparatus of claim 2 wherein the amount of said water soluble polymer in said apparatus is about 1% to 20% of the weight of said medium.

7. The apparatus of claim 2 wherein the amount of said water soluble polymer in said apparatus is about 1% to 10% of the weight of said medium.

8. The apparatus of claim 2 wherein the amount of said water soluble polymer in said apparatus is bout 1.5% to 5% of the weight of said medium.

9. The apparatus of claim 1 wherein the thickness of said barrier means is less than the wavelength of visible light.

10. An apparatus comprising a latex containment medium, liquid crystal material dispersed in plural volumes in said medium and wall means formed in plural volumes in said medium at least substantially between said liquid crystal material and said medium to impede the flow of said liquid crystal material wherein said wall means is formed from polyvinylpyrrolidone and wherein said medium induces a generally distorted alignment of said liquid crystal material which in response to said alignment at least one of scatters and absorbs light and which in response to a prescribed input reduces the amount of such scattering or absorption.

11. The apparatus of claim 10 wherein said wall means and said liquid crystal material have solubility parameters that differ by at least two Hildebrand units.

12. The apparatus of claims 10 or 11 further including a dye dissolved in said liquid crystal material.

13. The apparatus of claim 11 wherein said medium is selected from the group comprising polyethylenes, polypropylenes, polyurethanes, polyacrylics, and polysiloxanes.

14. The apparatus of claim 11 wherein said medium is a copolymer.

15. The apparatus of claim 14 wherein said copolymer is selected from the group comprising methacrylate-acrylonitriles, urethane-acrylics, acrylate-acrylonitriles, styrene-acrylonitriles, and vinylidene chloride-acrylonitriles.

16. The apparatus of claim 11 wherein said medium and said liquid crystal material have solubility parameters which differ by at least two Hildebrand units.

17. The apparatus of claim 11 wherein said medium, said wall means and said liquid crystal material have substantially matched indices of refraction in the presence of said prescribed input.

18. The apparatus of claim 11 wherein the thickness of said wall means is relatively thin compared to the wavelength of visible light incident thereon.

19. The apparatus of claim 11 wherein said liquid crystal material occupies about 20% to 60% of the volume of said apparatus.

20. The apparatus of claim 11 wherein said liquid crystal material is dispersed in said medium as particles having a diameter from about 1 micron to about 10 microns.

21. The apparatus of claim 10 further including electrode means for applying an electric field as the prescribed input, substrate means for supporting said electrode means, and circuit means for energizing said electrode means to apply said electric field.

22. The apparatus of claim 10 wherein the amount of said polyvinylpyrrolidone in said apparatus is about 0.5% to 30% of the weight of said medium.

23. The apparatus of claim 10 wherein the amount of polyvinylpyrrolidone in said apparatus is about 1% to 20% of the weight of said medium.

24. The apparatus of claim 10 wherein the amount of polyvinylpyrrolidone in said apparatus is about 1% to 10% of the weight of said medium.

25. The apparatus of claim 10 wherein the amount of polyvinylpyrrolidone in said apparatus is about 1.5% to 5% of the weight of said medium.

26. The apparatus of claim 10 wherein plural volumes in said medium include capsules containing quantities of said liquid crystal material, and said wall means is formed substantially along the surface of said capsules between said liquid crystal material and said medium.

27. The apparatus of claim 26 wherein passageways extend from said capsules and said wall means is formed in said passageways to impede the flow of said liquid crystal material therethrough.

28. The apparatus of claim 10 wherein said medium has undergone cross-linking.

29. An apparatus comprising a latex containment medium, liquid crystal material contained in plural volumes in said medium wherein passageways extend between at least some of said volumes and from at least some of said volumes to a surface of said medium and wherein said liquid crystal material includes operationally nematic liquid crystal having positive dielectric anisotropy, and a water soluble polymer forming a wall in plural volumes in said medium and along said passageways.

30. The apparatus of claim 29 wherein said water soluble polymer and said liquid crystal material have solubility parameters that differ by at least two Hildebrand units.

31. The apparatus of claim 29 wherein said water soluble polymer is formed from polyvinylpyrrolidone.

32. The apparatus of claim 30 wherein the amount of said water soluble polymer in said apparatus is about 0.5% to 30% of the weight of said medium.

33. The apparatus of claim 29 wherein plural volumes in said medium include capsules containing quantities of said liquid crystal material, and said wall is formed substantially along the surface of said capsules between said liquid crystal material and said medium.

34. The apparatus of claim 33 wherein said passageways extend from said capsules and said wall is formed in said passageways.

35. A method comprising:

mixing a liquid crystal material, polyvinylpyrrolidone and an aqueous phase to form a liquid crystal emulsion wherein said polyvinylpyrrolidone and said liquid crystal coalesce; and

combining said liquid crystal emulsion with a suspension that includes latex particles suspended in an aqueous phase such that said polyvinylpyrrolidone forms a wall substantially between said liquid crystal and said latex particles.

36. A method comprising:

combining a liquid crystal material and latex particles in an aqueous phase; and

emulsifying said liquid crystal material and thereafter adding a water soluble polymer to form a composition which when coated and dried has said liquid crystal material dispersed in plural volumes in a latex containment medium and said water soluble polymer forms a wall in said plural volumes in said medium at least between said liquid crystal material and said medium wherein said medium induces a generally distorted alignment of said liquid crystal material which in response to said alignment at least one of scatters and absorbs light and which in response to a prescribed input reduces the amount of such scattering or absorption.

37. The method of claim 36 wherein said liquid crystal material and said water soluble polymer have solubility parameters that differ by at least two Hildebrand units.

38. The method of claim 36 wherein said water soluble polymer is polyvinylpyrrolidone.

39. The apparatus of claim 36 wherein the amount of said water soluble polymer in said apparatus is about 0.5% to 30% of the weight of said medium.

40. The method of claim 36 wherein the amount of said water soluble polymer in said composition is about 1% to 20% of the weight of said medium.

41. The method of claim 36 wherein the amount of said water soluble polymer in said composition is about 1% to 10% of the weight of said medium.

42. The method of claim 36 wherein the amount of said water soluble polymer in said composition is about 1.5% to 5% of the weight of said medium.

43. The method of claim 36 wherein the thickness of said wall is less than the wavelength of visible light.

44. The method of claim 43 wherein said liquid crystal material and said medium have substantially matched indices of refraction in the presence of a prescribed input.

45. The method of claim 36 further comprising applying the composition to a substrate prior to drying the composition.

46. The method of claim 36 further comprising selecting said latex particles and said liquid crystal material wherein the difference between the solubility parameter of said liquid crystal material and the solubility parameter of said latex particles is greater than or equal to two Hildebrand units.

47. The method of claim 46 wherein said latex particles are selected from the group comprising polyethylenes, polypropylenes, polyurethanes, polyacrylics, and polysiloxanes.

48. The method of claim 46 wherein said latex particles are copolymers.

49. The method of claim 48 wherein said copolymers are selected from the group comprising methacrylate-acrylonitriles, urethane-acrylics, acrylate-acrylonitriles, styrene-acrylonitriles, and vinylidene chloride-acrylonitriles.

50. The method of claim 36 wherein the amount of said liquid crystal material is from about 30%. to about 60% of the volume of said liquid crystal emulsion, and the amount of said suspension is about 1 to 3 times the volume of said liquid crystal emulsion, and said suspension contains latex particles about 20% to about 60% of the volume thereof where said latex particles have diameters from about 0.01 microns to about 2.0 microns.

51. The method of claim 36 further comprising adding a dye to said liquid crystal material.