Branched polyol additives for electrophoretic media

Patent metadata

Field	Value
Publication number	US-9765015-B2
Application number	US-201715403370-A
Country	US
Kind code	B2
Filing date	Jan 11, 2017
Priority date	Jan 17, 2016
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

Additives for electrophoretic media comprising esters of branched polyols and fatty acids, such as esters of pentaerythritol propoxylate (5/4 PO/OH) and stearic acid. The fatty acids may be saturated or unsaturated, branched or unbranched. In some embodiments, the fatty acids are perfluorinated, or partially fluorinated. In some embodiments, the branched polyol will include oligomers of polypropylene oxide or polyethylene oxide. When the additives are included in an electrophoretic medium in a display, the resulting display has an improved contrast ratio and reducing ghosting.

First claim

The invention claimed is:

1. An electrophoretic medium comprising:
(a) a non-polar fluid;
(b) a plurality of first charged particles dispersed in the non-polar fluid; and
(c) an additive of Formula I

wherein R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of —OH, —(CH 2 ) m OH, —(OCH 2 CH 2 ) n OH, —(OCH 2 CHCH 3 ) q OH, —OCOR 5 , —(CH 2 ) r OCOR 5 , —(OCH 2 CH 2 ) t OCOR 5 , and —(OCH 2 CHCH 3 ) u OCOR 5 , wherein each R 5 is independently a C 5 -C 28 branched or unbranched fluoroalkane, and m, n, q, r, t, and u are independently integers from 1 to 30, and
wherein at least one of R 1 , R 2 , R 3 , or R 4 is —OCOR 5 , —(CH 2 ) r OCOR 5 , —(OCH 2 CH 2 ) t OCOR 5 , or —(OCH 2 CHCH 3 ) u OCOR 5 .

2. The electrophoretic medium of claim 1 , wherein R 5 is a C 10 -C 20 unbranched fluoroalkane.

3. The electrophoretic medium of claim 1 , wherein R 5 is C 17 F 35 .

4. The electrophoretic medium of claim 1 , R 1 , R 2 , and R 3 are —OH, R 4 is —OCOR 5 , and R 5 is a C 5 -C 28 branched or unbranched fluoroalkane.

5. The electrophoretic medium of claim 4 , wherein R 5 is C 17 F 35 .

6. The electrophoretic medium of claim 1 , further comprising a plurality of second charged particles dispersed in the non-polar fluid, wherein the first and second charged particles have opposite charges.

7. The electrophoretic medium of claim 1 , further comprising an ionic surfactant.

8. The electrophoretic medium of claim 7 , wherein the ionic surfactant comprises a quaternary amine.

9. An encapsulated electrophoretic medium comprising the electrophoretic medium of claim 1 .

10. The encapsulated electrophoretic medium of claim 9 , wherein the electrophoretic medium is encapsulated in a microcell or a protein coacervate.

11. The encapsulated electrophoretic medium of claim 10 , wherein the protein coacervate comprises gelatin.

12. The electrophoretic medium of claim 1 , wherein the electrophoretic medium is dispersed in a polymer.

13. The electrophoretic medium of claim 1 , wherein the first charged particles comprise titania, carbon black, or copper chromite.

14. The electrophoretic medium of claim 1 , wherein a ratio of additive to first charged particles is greater than 1:500.

15. The electrophoretic medium of claim 1 , wherein the conductivity of the electrophoretic medium is less than 300 pS/m.

16. The electrophoretic medium of claim 1 , further comprising a plurality of second charged particles and a plurality of third charged particles dispersed in the nonpolar fluid, wherein the first, the second, or the third charged particles are red, green, blue, cyan, yellow, or magenta.

17. The electrophoretic medium of claim 1 , wherein the non-polar fluid comprises C 6 -C 18 branched alkanes.

18. The electrophoretic medium of claim 1 , wherein the non-polar fluid comprises C 7 -C 10 branched alkanes.

19. An additive of Formula II:

wherein R 5 is a C 5 -C 28 branched or unbranched alkane or fluoroalkane.

20. The additive of claim 19 , wherein R 5 is a C 10 -C 20 unbranched alkane or fluoroalkane.

21. The additive of claim 19 , wherein R 5 is C 17 H 35 or C 17 F 35 .

22. The additive of claim 19 , wherein R 5 is a stearate.

23. An additive of Formula III:

wherein R 5 and R 6 are independently C 5 -C 28 branched or unbranched alkanes or fluoroalkanes.

24. The additive of claim 23 , wherein R 5 or R 6 is a C 10 -C 20 unbranched alkane of fluoroalkane.

25. The additive of claim 23 , wherein R 5 or R 6 is C 17 H 35 or C 17 F 35 .

26. The additive of claim 23 , wherein R 5 or R 6 is a stearate.

Assignees

• E Ink California Llc

Inventors

• Shao Lin
• Gu Haiyan
• Sofiyev Vladimir
• Wang Ming

Classifications

• C07C69/33 Primary

  esterified with hydroxy compounds having more than three hydroxy groups (esters of sugars C07H) · CPC title

• G02F2001/1678

  characterised by the composition or particle type · CPC title

• C07C69/34 Primary

  Esters of acyclic saturated polycarboxylic acids having an esterified carboxyl group bound to an acyclic carbon atom · CPC title

• C09D5/448 Primary

  characterised by the additives used (C09D5/4403 - C09D5/4476, C09D5/4492 take precedence) · CPC title

• C07C69/18

  of trihydroxylic compounds · CPC title