Cellulose Esters with High Hyrdoxyl Content and Their Use in Liquid Crystal Displays

• US 20090096962A1
• Filed: 04/09/2008
• Published: 04/16/2009
• Est. Priority Date: 05/14/2007
• Status: Abandoned Application

• Current Assignee: Eastman Chemical Company
• Original Assignee: Eastman Chemical Company
• Inventors: Zhang, Dong, Shelton, Michael Charles, Germroth, Ted Calvin, Harris, Frank Wayne
• Application Number:
  US12/100,092
• Publication Number:
  US 20090096962A1
• Time in Patent Office: Days
• US Class Current: 349/96
• CPC Class Codes: C08B 3/06 Cellulose acetate , e.g. mono-acetate, di-acetate or tri-acetate
• CPC Class Codes: C08B 3/08 of monobasic organic acids with three or more carbon atoms, e.g. propionate or butyrate
• CPC Class Codes: C08B 3/16 Preparation of mixed organic cellulose esters , e.g. cellulose aceto-formate or cellulose aceto-propionate
• CPC Class Codes: C08B 3/18 Aceto-butyrates
• CPC Class Codes: C08J 2301/12 Cellulose acetate
• CPC Class Codes: C08J 2301/14 Mixed esters
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08K 5/0016 Plasticisers
• CPC Class Codes: C08L 1/12 Cellulose acetate
• CPC Class Codes: C08L 1/14 Mixed esters, e.g. cellulose acetate-butyrate
• 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: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• 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

Abstract

The invention relates to the preparations and uses of cellulose esters with a high degree of substitution of hydroxyl groups (also called high DS_OH cellulose esters) as substrates and/or negative C-plate optical compensation films in LCD applications.

Claims

1. A film comprising:

70 to 100 weight percent of a cellulose acetate with a degree of substitution of hydroxyl groups from 0.40 to 2.00;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total weight of the cellulose acetate, the plasticizer and the organic solvent and

wherein the film is unstretched.

2. The film of claim 1, wherein nx=ny and nx>

nz and ny>

nz.

3. The film of claim 1 wherein the degree of substitution of hydroxyl groups ranges from 0.65 to 2.00.

4. The film of claim 1 wherein the degree of substitution of hydroxyl groups ranges from 0.95 to 2.00.

5. The film of claim 1 wherein the degree of substitution of hydroxyl groups ranges from 1.01 to 2.00.

6. The film of claim 1 wherein the birefringence at 633 nm, Δ

n⁶³³, is less than zero to about −

0.010.

7. The film of claim 1 wherein the birefringence at 633 nm, Δ

n⁶³³, ranges from equal to or less than −

0.001 to about −

0.010.

8. The film of claim 1 wherein the film has a thickness ranging from 3 microns to 300 microns.

9. The film of claim 1 wherein film thickness ranging from greater than 300 microns to 1000 microns.

10. The film of claim 1 wherein the plasticizer is selected from the group consisting of triphenyl phosphate (TPP), tricresyl phosphate, cresyl phenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethyl hexyl phthalate, butyl benzyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, dibenzyl phthalate, triethyl citrate, acetyl trimethyl citrate, acetyl tributyl citrate. methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate (EPEG), propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, propyl phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl glycolate, butyl oleate, methyl acetyl ricinolate, dibutyl sebacate, triacetin, glucose pentapropionate, glucose pentaisobutyrate, glucose pentatbutyrate, fructose pentapropionate, fructose pentaisobutyrate, fructose pentatbutyrate, xylose tetrapropionate, xylose tetraisobutyrate, xylose tetrabutryate, xylitol pentapropionate, xylitol pentaisobutryate, xylitol pentabutyrate, mannitol hexapropionate, mannitol hexaisobutyrate, mannitol hexabutyrate and mixtures thereof.

11. The film of claim 1 where the organic solvent is selected from the group consisting of methylene chloride, chloroform, dichloroethane, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, methyl acetate, ethyl acetate, amyl acetate, propyl acetate, butyl acetate, acetone, tetrahydrofuran, 1,3-dioxolan, 1,4-dioxane, cyclohexanone, ethyl formate, nitroethane, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), methyl amyl ketone (MAK), methyl isoamyl ketone (MIAK), toluene, methanol, ethanol, propanol, isopropanol, butanol, t-butanol, sec-butanol, acetic acid, propionic acid, butyric acid and mixtures thereof.

12. A liquid crystal display comprising at least one film of claim 1.

13. A polarizer plate for a liquid crystal display comprising at least one film of claim 1.

14. A wave plate for a liquid crystal display comprising at least one film of claim 1.

15. A single layer compensation sheet comprising the film of claim 1.

16. A multi-layer compensation sheet comprising at least one film of claim 1.

17. The film of claim 1 wherein the film functions as both a substrate for LCD components and as a compensation sheet in liquid crystal displays.

18. The film of claim 1 comprising at least one layer of a multifunctional film wherein the film functions as a substrate or protective layer for liquid crystal display components and provides compensation.

19. The film of claim 1 wherein the film thickness ranges from about 3 microns to about 1000 microns.

20. The film of claim 1 comprising 0-30 weight percent of additives selected from the group comprising matting agents, UV absorbers, antioxidants, and dyes.

21. The film of claim 20 wherein the additives are birefringence enhancing substances selected from the group consisting of liquid crystal compounds, discotic compounds, and/or rod-like compounds.

22. A polarizer for a liquid crystal display comprising the film of claim 1 and another substrate layer, where the second substrate comprises, TAC film, a CAP film with DS_OH between 0 and 0.399, a CAB film with DS_OH between 0 and 0.399, or cyclic olefin polymer (COP) film.

23. A liquid crystal display comprising the film of claim 1 and a polymer layer, wherein the film is laminated onto the polymer layer.

24. A liquid crystal display comprising the film of claim 1 and a second layer wherein the film is solvent cast onto the second layer.

25. A polarizer for a liquid crystal display comprising a first and a second cellulose acetate film of claim 1 and a polyvinyl alcohol film having a first and second surface, wherein the first and second cellulose acetate films contact the first and second surfaces of the polyvinyl alcohol film and wherein the first and second cellulose acetate films of claim 1 are not saponified.

26. A polarizer for a liquid crystal display comprising a first and a second cellulose acetate film of claim 1 and a polyvinyl alcohol film having a first and second surface, wherein the first and second cellulose acetate films contact the first and second surfaces of the polyvinyl alcohol film and wherein the first and second cellulose acetate films of claim 1 are saponified.

27. The film of claim 2 wherein the film thickness ranges from about 3 microns to about 1000 microns.

28. The film of claim 2 comprising 0-30 weight percent of additives selected from the group consisting of matting agents, UV absorbers, antioxidants, and dyes.

29. The film of claim 28 wherein the additives are birefringence enhancing substances selected from the group consisting of liquid crystal compounds, discotic liquid crystal compounds, and rod-like liquid crystal compounds.

38. The film of claim 1 where the number average molecular weight (M_n) of the cellulose acetate, as determined by gel permeation chromatography (GPC), ranges from 1,500 to 200,000.

39. The film of claim 1 where the inherent viscosity (IV) of the cellulose acetate ranges from 0.050 to 3.0 deciliters/gram.

30. A film comprisingto 100 weight percent of a cellulose acetate propionate with a degree of substitution of hydroxyl groups from 0.50 to 2.00, a degree of substitution of acetyl groups of 0.01 to 2.59, and a degree of substitution of propionyl groups of 0.01 to 2.59, wherein the sum of the degrees of substitution of acetyl, propionyl, and hydroxyl groups equals 3.0;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total of the cellulose acetate propionate, the plasticizer and the organic solvent.

31. A film comprising:

70 to 100 weight percent of a cellulose acetate propionate with a degree of substitution of hydroxyl groups from 0.65 to 2.00, a degree of substitution of acetyl groups of 0.01 to 2.34, and a degree of substitution of propionyl groups of 0.01 to 2.34, wherein the sum of the degrees of substitution of acetyl, propionyl, and hydroxyl groups equals 3.0;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total of the cellulose acetate propionate, the plasticizer and the organic solvent.

32. A film comprising:

70 to 100 weight percent of a cellulose acetate propionate with a degree of substitution of hydroxyl groups from 0.95 to 2.00, a degree of substitution of acetyl groups of 0.01 to 2.04, and a degree of substitution of propionyl groups of 0.01 to 2.04, wherein the sum of the degrees of substitution of acetyl, propionyl, and hydroxyl groups equals 3.0;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total of the cellulose acetate propionate, the plasticizer and the organic solvent.

33. A film comprising:

70 to 100 weight percent of a cellulose acetate propionate with a degree of substitution of hydroxyl groups from 1.01 to 2.00, a degree of substitution of acetyl groups of 0.01 to 1.99, and a degree of substitution of propionyl groups of 0.01 to 1.99, wherein the sum of the degrees of substitution of acetyl, propionyl, and hydroxyl groups equals 3.0;

0 to 30 weight percent of a plasticizer or a combination of plasticizers; and

0 to 30 weight percent of an organic solvent or blend of organic solvents,

wherein the weight percent is based on the total of the cellulose acetate propionate, the plasticizer and the organic solvent.

34. A film comprising:

70 to 100 weight percent of a cellulose acetate butyrate with a degree of substitution of hydroxyl groups from 0.40 to 2.00, a degree of substitution of acetyl groups of 0.01 to 2.59, and a degree of substitution of butyryl groups of 0.01 to 2.59, wherein the sum of the degrees of substitution of acetyl, butyryl, and hydroxyl groups equals 3.0;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total of the cellulose acetate butyrate, the plasticizer and the organic solvent.

35. A film comprising:

70 to 100 weight percent of a cellulose acetate butyrate with a degree of substitution of hydroxyl groups from 0.65 to 2.00, a degree of substitution of acetyl groups of 0.01 to 2.34, and a degree of substitution of butyryl groups of 0.01 to 2.34, wherein the sum of the degrees of substitution of acetyl, butyryl, and hydroxyl groups equals 3.0;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total of the cellulose acetate butyrate, the plasticizer and the organic solvent.

36. A film comprising:

70 to 100 weight percent of a cellulose acetate butyrate with a degree of substitution of hydroxyl groups from 0.95 to 2.00, a degree of substitution of acetyl groups of 0.01 to 2.04, and a degree of substitution of butyryl groups of 0.01 to 2.04, wherein the sum of the degrees of substitution of acetyl, butyryl, and hydroxyl groups equals 3.0;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total of the cellulose acetate butyrate, the plasticizer and the organic solvent.

37. A film comprising:

70 to 100 weight percent of a cellulose acetate butyrate with a degree of substitution of hydroxyl groups from 1.01 to 2.00, a degree of substitution of acetyl groups of 0.01 to 0.98, and a degree of substitution of butyryl groups of 0.01 to 0.98, wherein the sum of the degrees of substitution of acetyl, butyryl, and hydroxyl groups equals 3.0;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total of the cellulose acetate butyrate, the plasticizer and the organic solvent.

40. A process of forming a high DS_OH film, the process comprising

hydrolyzing a cellulose ester having a degree of substitution of acyl groups ranging from 2.6 to 3.0 by contacting the cellulose ester with an acidic or basic saponification agent to produce a hydrolyzed cellulose ester, and

forming a film from the hydrolyzed cellulose ester,

wherein the film has a negative birefringence at 633 nm, Δ

n⁶³³, compared to a film made from the unhydrolyzed cellulose ester.

41. The process of claim 40 wherein the cellulose ester is dissolved in an organic solvent, heated to a temperature ranging from about 0°

C. to about 100°

C. in the presence of water and a saponification catalyst.

42. The process of claim 40 further comprising neutralizing the saponification agent.

43. The process of claim 41 wherein the organic solvent comprises an organic carboxylic acid.

44. The process of claim 43 wherein the organic solvent comprises acetic acid, propionic acid, butyric acid or mixtures thereof.

45. The process of claim 40 where the saponification agent comprises a mineral acid.

46. The process of claim 45 where the saponification agent comprises sulfuric acid.

47. The process of claim 45 where the saponification agent comprises hydrochloric acid.

48. The process of claim 40 where the saponification agent comprises a base.

49. The process of claim 40 where the saponification agent is a solid.

50. A film comprising:

70 to 100 weight percent of a cellulose acetate with a degree of substitution of hydroxyl groups from greater than 1.23 to 2.00;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total weight of the cellulose acetate, the plasticizer and the organic solvent and

wherein the film is stretched.

51. The film of claim 50 where the film is biaxially stretched.

52. The film of claim 50 where the film is uniaxially stretched.

53. The film of claim 50 where the film is planar stretched.

54. The film of claim 50 where the film is stretched at a temperature greater than the Tg of the film.

55. The film of claim 50 with an R_th between −

240 and −

300 and being 60 micron thick after stretching.

56. The film of claim 50 with an R_th greater than (i.e. more negative than) −

300 and being 60 micron thick after stretching.

57. A film comprising:

70 to 100 weight percent of a cellulose acetate with a degree of substitution of hydroxyl groups from greater than 1.01 to 2.00;

0 to 30 weight percent of a plasticizer; and

0 to 30 weight percent of an organic solvent,

wherein the weight percent is based on the total weight of the cellulose acetate, the plasticizer and the organic solvent and

wherein the film is stretched.

58. The film of claim 57 wherein the film is biaxially stretched.

59. The film of claim 57 wherein the film is uniaxially stretched.

60. The film of claim 57 wherein the film is planar stretched.

61. The film of claim 57 wherein the film is stretched at a temperature greater than the Tg of the film.

62. The film of claim 57 having a 60 micron thickness and an R_th between −

240 and −

300.

63. The film of claim 57 having a 60 micron thickness and an R_th greater than (i.e. more negative than) −

300.