RETARDATION FILM, BRIGHTNESS ENHANCEMENT FILM, POLARIZING PLATE, PRODUCING METHOD OF A RETARDATION FILM, AND LIQUID CRYSTAL DISPLAY

• US 20090251642A1
• Filed: 07/17/2007
• Published: 10/08/2009
• Est. Priority Date: 07/18/2006
• Status: Abandoned Application

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Dai Nippon Printing Company Limited
• Inventors: Nakamura, Runa, Kuroda, Takashi, Fukuda, Masanori, Nakagawa, Hiroki, Inomata, Yuya
• Application Number:
  US12/374,113
• Publication Number:
  US 20090251642A1
• Time in Patent Office: Days
• US Class Current: 349/75
• CPC Class Codes: B32B 23/04 comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a glass layer B32B17/08
• CPC Class Codes: B32B 23/08 of synthetic resin
• CPC Class Codes: B32B 23/14 characterised by containing special compounding ingredients
• CPC Class Codes: B32B 23/20 comprising esters
• CPC Class Codes: B32B 2307/40 having particular optical properties light or UV resistant B32B2307/71
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2307/418 Refractive
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2307/54 Yield strength; Tensile strength
• CPC Class Codes: B32B 2307/706 Anisotropic
• CPC Class Codes: B32B 2307/724 Permeability to gases, adsorption
• CPC Class Codes: B32B 2307/7242 Non-permeable
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 27/18 characterised by the use of special additives
• CPC Class Codes: B32B 27/281 comprising polyimides
• CPC Class Codes: B32B 27/308 comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/325 comprising polycycloolefins
• CPC Class Codes: B32B 27/40 comprising polyurethanes
• 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 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 2201/50 : Protective arrangements
• CPC Class Codes: G02F 2413/02 : Number of plates being 2
• CPC Class Codes: G02F 2413/12 : Biaxial compensators

Abstract

A retardation film that is used as a polarizing plate protective film, thereby making it possible to yield a polarizing plate which is very good in durability and has a viewing angle compensation function. The retardation film has: an optical anisotropic film, in which a relation of nx>ny is realized between a refractive index “nx” in a slow axis direction of an in-plane direction and a refractive index “ny” in a fast axis direction of the in-plane direction; and a retardation layer formed on the optical anisotropic film and containing a liquid crystalline material, in which a relation of nx≦ny<nz is realized between refractive indexes “nx” and “ny” in arbitrary directions “x” and “y” of an in-plane direction which are perpendicular to each other and a refractive index “nz” in a thickness direction. The optical anisotropic film uses a transparent substrate having a cellulose derivative.

Claims

1-20. -20. (canceled)

21. A retardation film, comprising:

an optical anisotropic film, in which a relation of nx>

ny is realized between a refractive index “

nx”

in a slow axis direction of an in-plane direction and a refractive index “

ny”

in a fast axis direction of the in-plane direction; and

a retardation layer formed on the optical anisotropic film and containing a liquid crystalline material, in which a relation of nx≦

ny<

nz is realized between refractive indexes “

nx” and

“

ny”

in arbitrary directions “

x” and

“

y”

of an in-plane direction which are perpendicular to each other and a refractive index “

nz”

in a thickness direction,

wherein the optical anisotropic film uses a transparent substrate comprising a cellulose derivative.

22. The retardation film according to claim 21, wherein the optical anisotropic film has:

the transparent substrate, and

an optical anisotropic layer formed on the transparent substrate and containing a urethane resin.

23. The retardation film according to claim 21, wherein the optical anisotropic film has:

the transparent substrate, and

an optical anisotropic layer formed on the transparent substrate and containing the cellulose derivative, which constitutes the transparent substrate, and an optical anisotropic material having a retardation exhibiting a wavelength dependency of a normal dispersion type.

24. The retardation film according to claim 23, wherein the optical anisotropic material contains a monofunctional polymerizable liquid crystal compound having, in a molecule thereof, a single polymerizable functional group.

25. The retardation film according to claim 21, wherein the cellulose derivative is triacetylcellulose.

26. A brightness enhancement film, comprising:

the retardation film as recited in claim 21, and

a cholesteric liquid crystal layer formed on the retardation layer of the retardation film, and containing a liquid crystalline material in a cholesteric sequence state.

27. A polarizing plate, comprising:

the retardation film as recited in claim 21,

a polarizer formed on the optical anisotropic film of the retardation film, and on a side opposite to the retardation-layer-formed side of the optical anisotropic film, and

a polarizing plate protective film formed on the polarizer.

28. A polarizing plate, comprising:

the brightness enhancement film as recited in claim 26,

a polarizer formed on the optical anisotropic film of the brightness enhancement film, and on a side opposite to the retardation-layer-formed side of the optical anisotropic film, and

a polarizing plate protective film formed on the polarizer.

29. The polarizing plate according to claim 27, wherein the polarizing plate protective film comprises a cycloolefin resin or an acrylic resin.

46. A liquid crystal display, wherein the retardation film as recited in claim 21 is used.

47. A liquid crystal display, wherein the brightness enhancement film as recited in claim 26 is used.

48. A liquid crystal display, wherein the polarizing plate as recited in claim 27 is used.

49. A liquid crystal display, wherein the polarizing plate as recited in claim 28 is used.

30. A producing method of a retardation film, comprising steps of:

an optical anisotropic film forming step of using a transparent substrate comprising a cellulose derivative, coating on the transparent substrate an optical-anisotropic-layer-forming coating solution in which an optical anisotropic material having a retardation exhibiting a wavelength dependency of a normal dispersion type is dissolved in a solvent, and thereby forming an optical anisotropic film in which an optical anisotropic layer is formed on the transparent substrate;

a stretching step of stretching the optical anisotropic film formed in the optical anisotropic film forming step; and

a retardation layer forming step of forming, on the optical anisotropic layer of the optical anisotropic film stretched in the stretching step, a retardation layer containing a liquid crystalline material, in which a relation of nx≦

ny<

nz is realized between refractive indexes “

nx” and

“

ny”

in arbitrary directions “

x” and

“

y”

of an in-plane direction which are perpendicular to each other and a refractive index “

nz”

in a thickness direction.

34. The producing method of a retardation film according to claim 30, wherein the solvent contains a ketone solvent having a boiling point of 100°

C. or higher.

38. The producing method of a retardation film according to claim 34, wherein the ketone solvent is cyclopentanone or cyclohexanone.

42. The producing method of a retardation film according to claim 30, wherein the cellulose derivative is triacetylcellulose.

50. A liquid crystal display, wherein a retardation film produced by the retardation film producing method as recited in claim 30 is used.

31. A producing method of a retardation film, comprising steps of:

an optical anisotropic film forming step of using a transparent substrate comprising a cellulose derivative, coating on the transparent substrate an optical-anisotropic-layer-forming coating solution in which an optical anisotropic material having a retardation exhibiting a wavelength dependency of a normal dispersion type is dissolved in a solvent, and thereby forming an optical anisotropic film in which an optical anisotropic layer is formed on the transparent substrate;

a retardation layer forming step of forming, on the optical anisotropic layer of the optical anisotropic film formed in the optical anisotropic film forming step, a retardation layer containing a liquid crystalline material, in which a relation of nx≦

ny<

nz is realized between refractive indexes “

nx” and

“

ny”

in arbitrary directions “

x” and

“

y”

of an in-plane direction which are perpendicular to each other and a refractive index “

nz”

in a thickness direction, thereby forming an optical laminate in which the retardation layer is formed on the optical anisotropic layer; and

a stretching step of stretching the optical laminate formed in the retardation layer forming step.

35. The producing method of a retardation film according to claim 31, wherein the solvent contains a ketone solvent having a boiling point of 100°

C. or higher.

39. The producing method of a retardation film according to claim 35, wherein the ketone solvent is cyclopentanone or cyclohexanone.

43. The producing method of a retardation film according to claim 31, wherein the cellulose derivative is triacetylcellulose.

51. A liquid crystal display, wherein a retardation film produced by the retardation film producing method as recited in claim 31 is used.

32. A producing method of a retardation film, comprising steps of:

an optical anisotropic film forming step of using a transparent substrate comprising a cellulose derivative, coating on the transparent substrate an optical-anisotropic-layer-forming coating solution in which an optical anisotropic material having a retardation exhibiting a wavelength dependency of a normal dispersion type is dissolved in a solvent, and thereby forming an optical anisotropic film in which an optical anisotropic layer is formed on the transparent substrate;

a stretching step of stretching the optical anisotropic film formed in the optical anisotropic film forming step; and

a retardation layer forming step of forming, on a surface opposite to the optical-anisotropic-layer-formed surface of the optical anisotropic film stretched in the stretching step, a retardation layer containing a liquid crystalline material, in which a relation of nx≦

ny<

nz is realized between refractive indexes “

nx” and

“

ny”

in arbitrary directions “

x” and

“

y”

of an in-plane direction which are perpendicular to each other and a refractive index “

nz”

in a thickness direction.

36. The producing method of a retardation film according to claim 32, wherein the solvent contains a ketone solvent having a boiling point of 100°

C. or higher.

40. The producing method of a retardation film according to claim 36, wherein the ketone solvent is cyclopentanone or cyclohexanone.

44. The producing method of a retardation film according to claim 32, wherein the cellulose derivative is triacetylcellulose.

52. A liquid crystal display, wherein a retardation film produced by the retardation film producing method as recited in claim 32 is used.

33. A producing method of a retardation film, comprising steps of:

an optical anisotropic film forming step of using a transparent substrate comprising a cellulose derivative, coating on the transparent substrate an optical-anisotropic-layer-forming coating solution in which an optical anisotropic material having a retardation exhibiting a wavelength dependency of a normal dispersion type is dissolved in a solvent, and thereby forming an optical anisotropic film in which an optical anisotropic layer is formed on the transparent substrate;

a retardation layer forming step of forming, on a surface opposite to the optical-anisotropic-layer-formed surface of the optical anisotropic film formed in the optical anisotropic film forming step, a retardation layer containing a liquid crystalline material, in which a relation of nx≦

ny<

nz is realized between refractive indexes “

nx” and

“

ny”

in arbitrary directions “

x” and

“

y”

of an in-plane direction which are perpendicular to each other and a refractive index “

nz”

in a thickness direction, and thereby forming an optical laminate in which the retardation layer is formed on the optical anisotropic layer; and

a stretching step of stretching the optical laminate formed in the retardation layer forming step.

37. The producing method of a retardation film according to claim 33, wherein the solvent contains a ketone solvent having a boiling point of 100°

C. or higher.

41. The producing method of a retardation film according to claim 37, wherein the ketone solvent is cyclopentanone or cyclohexanone.

45. The producing method of a retardation film according to claim 33, wherein the cellulose derivative is triacetylcellulose.

53. A liquid crystal display, wherein a retardation film produced by the retardation film producing method as recited in claim 33 is used.