Claims
- 1. A triacetyl cellulose film comprising (a) an unsubstituted triphenyl phosphate compound and (b) a lower alkyl-substituted triphenyl phosphate ester compound.
- 2. The film of claim 1 wherein compound (b) is present in an amount sufficient to reduce the rate of water vapor transmission of the film compared to the same film without compound (b).
- 3. The film of claim 1 wherein compound (b) is a fully esterified phosphate compound.
- 4. The film of claim 3 wherein compound (b) is a mono(alkylphenyl)-di(unsubstituted phenyl) phosphate ester compound.
- 5. The film of claim 3 wherein compound (b) is a di(alkylphenyl)-mono(unsubstituted phenyl) phosphate ester compound.
- 6. The film of claim 3 wherein compound (b) is a tri(alkylphenyl)-phosphate ester compound.
- 7. The film of claim 3 wherein compound (b) is represented by formula (I):
- 8. The film of claim 7 wherein at least one R group is an independently selected lower alkyl group having less than 8 carbon atoms.
- 9. The film of claim 8 wherein at least one R group is a butyl group.
- 10. The film of claim 9 wherein the R group is a t-butyl group.
- 11. The film of claim 7 comprising a mixture of two or more fully esterified phosphate ester compounds with each n selected from the group consisting of 1, 2, and 3.
- 12. The film of claim 1 wherein the total amount of compounds (a) in the film is 6-15% by wt. of the film.
- 13. The film of claim 1 wherein the total amount of compounds (a) in the film is 10-12 % by wt. of the film.
- 14. The film of claim 3 wherein the total amount of compounds (b) in the film is 1-5 % by wt. of the film.
- 15. The film of claim 14 wherein the total amount of compounds (b) in the film is 1-4 % by wt. of the film.
- 16. The film of claim 1 wherein the triacetylcellulose film exhibits a birefringence such that the retardation of a 80 micron thick film is less than 5 nm.
- 17. The film of claim 1 wherein the degree of acetylation of the triacetylcellulose is 2.4 to 3 sites per cellulose unit.
- 18. The film of claim 1 wherein the degree of acetylation of the triacetylcellulose is 2.7 to 2.9 sites per cellulose unit.
- 19. The film of claim 1 wherein the weight average molecular weight of the triacetylcellulose is 150.000-250,000.
- 20. The film of claim 19 wherein the weight average molecular weight of the triacetylcellulose is 180,000-220,000.
- 21. A method of imparting improved water vapor transmission resistance to a triacetylcellulose film comprising adding the components of claim 1 to a cellulosic dope prior to casting.
- 22. A polarizer element comprising a laminate of the film of claim 1.
- 23. A liquid crystal imaging element comprising the polarizer element of claim 22.
- 24. An optical device containing the liquid crystal element of claim 23.
- 25. A triacetylcellulose film comprising a combination plasticizer containing (a) at least 6 wt % of the film of an unsubstituted triphenyl phosphate compound and (b) at least 1% of the film of a fully esterified lower alkyl-substituted triphenyl phosphate ester compound.
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is related to an application directed to a TAC film comprising a plasticizer containing an aromatic polyol-bridged polyphosphate compound co-filed herewith under Attorney Docket No. 83566/AEK.