Electro-optic display and materials for use therein

• US 7,477,444 B2
• Filed: 09/22/2006
• Issued: 01/13/2009
• Est. Priority Date: 09/22/2006
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated, Versum Materials US Inc.
• Original Assignee: E Ink Corporation & Air Products and Chemical Incorporated
• Inventors: Miller, David, Bender, Jared, Klingenberg, Eric H., Fazel, Shafiq N., Cao, Lan
• Primary Examiner(s): Lester; Evelyn A.
• Application Number:
  US11/534,336
• Publication Number:
  US 20080074730A1
• Time in Patent Office: 844 Days
• Field of Search: 359/296, 428/844.5, 428/844.71, 428/844.8
• US Class Current: 359/296
• CPC Class Codes: C08G 18/0823 containing carboxylate salt groups or groups forming them
• CPC Class Codes: C08G 18/12 using two or more compounds having active hydrogen in the first polymerisation step
• CPC Class Codes: C08G 18/3228 acyclic
• CPC Class Codes: C08G 18/348 Hydroxycarboxylic acids
• CPC Class Codes: C08G 18/4277 Caprolactone and/or substituted caprolactone
• CPC Class Codes: C08G 18/6659 with compounds of group C08G18/34
• CPC Class Codes: C08G 18/758 containing two or more cycloaliphatic rings
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1675 Constructional details

Abstract

A polyurethane is formed from an isocyanate and a polyester diol having a molecular weight less than about 2000, or a polyester diol comprising two polyester diol segments connected by a steric hindrance group, each of the polyester diol segments having a molecular weight less than about 2000. The polyurethane is useful as a binder in electro-optic displays, and in components used to form such displays.

Claims

1. A polyurethane formed from an isocyanate and a polyester diol having a molecular weight less than about 2000, or a polyester diol comprising two polyester diol segments connected by a steric hindrance group, each of the polyester diol segments having a molecular weight less than about 2000.

2. A polyurethane according to claim 1 formed from polycaprolactone diol having a molecular weight less than about 1500.

3. A polyurethane according to claim 2 wherein the polycaprolactone diol comprises two polycaprolactone segments connected by a bending group, each of the polycaprolactone segments having a molecular weight not greater than about 1500.

4. A polyurethane according to claim 3 wherein the steric hindrance group comprises a quaternary carbon atom.

5. A polyurethane according to claim 4 wherein the steric hindrance group comprises a —

C(CH₃)₂—

grouping.

6. A polyurethane according to claim 1 in the form of an aqueous latex.

9. An electro-optic display comprising a layer of a solid electro-optic material, and at least one electrode arranged to apply an electric field to the layer of electro-optic material, the layer of electro-optic material comprising a binder, wherein the binder comprises a polyurethane according to claim 1.

10. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising a display according to claim 9.

13. An article of manufacture comprising in order:

a light-transmissive electrically-conductive layer;

a layer of a solid electro-optic medium comprising a binder and in electrical contact with the electrically-conductive layer;

an adhesive layer; and

a release sheet,

wherein the binder comprises a polyurethane according to claim 1.

15. An article of manufacture comprising:

a layer of a solid electro-optic medium comprising a binder and having first and second surfaces on opposed sides thereof;

a first adhesive layer on the first surface of the layer of electro-optic medium;

a release sheet disposed on the opposed side of the first adhesive layer from the layer of electro-optic medium; and

a second adhesive layer on the second surface of the layer of electro-optic medium,

wherein the binder comprises a polyurethane according to claim 1.

17. An article of manufacture for use in forming an electro-optic display, the article of manufacture comprising, in order:

at least one of a light-transmissive protective layer and a light-transmissive electrically-conductive layer;

an adhesive layer;

a layer of a solid electro-optic medium comprising a binder; and

a release sheet,

wherein the binder comprises a polyurethane according to claim 1.

19. An article of manufacture for use in forming an electro-optic display, the article of manufacture comprising:

a layer of a solid electro-optic medium comprising a binder and having first and second surfaces on opposed sides thereof;

a first release sheet covering the first surface of the layer of solid electro-optic medium; and

a second release sheet covering the second surface of the layer of solid electro-optic medium,

wherein the binder comprises a polyurethane according to claim 1.

21. An article of manufacture for use in forming an electro-optic display, the article of manufacture comprising, in order:

a first release sheet;

a layer of a solid electro-optic medium comprising a binder;

an adhesive layer; and

a second release sheet,

wherein the binder comprises a polyurethane according to claim 1.

7. A polyurethane formed from an isocyanate and a polyester diol, the polyurethane not crystallizing between about −

10°

C. and about 70°

C. when coated as a thin film.

8. A polyurethane according to claim 7 in the form of an aqueous latex.

11. An electro-optic display comprising a layer of a solid electro-optic material, and at least one electrode arranged to apply an electric field to the layer of electro-optic material, the layer of electro-optic material comprising a binder, wherein the binder comprises a polyurethane according to claim 7.

12. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising a display according to claim 11.

14. An article of manufacture comprising in order:

a light-transmissive electrically-conductive layer;

a layer of a solid electro-optic medium comprising a binder and in electrical contact with the electrically-conductive layer;

an adhesive layer; and

a release sheet,

wherein the binder comprises a polyurethane according to claim 7.

16. An article of manufacture comprising:

a layer of solid electro-optic medium comprising a binder and having first and second surfaces on opposed sides thereof,

a first adhesive layer on the first surface of the layer of electro-optic medium;

a release sheet disposed on the opposed side of the first adhesive layer from the layer of electro-optic medium; and

a second adhesive layer on the second surface of the layer of electro-optic medium,

wherein the binder comprises a polyurethane according to claim 7.

18. An article of manufacture for use in forming an electro-optic display, the article of manufacture comprising, in order:

at least one of a light-transmissive protective layer and a light-transmissive electrically-conductive layer;

an adhesive layer;

a layer of a solid electro-optic medium comprising a binder; and

a release sheet,

wherein the binder comprises a polyurethane according to claim 7.

20. An article of manufacture for use in forming an electro-optic display, the article of manufacture comprising:

a layer of a solid electro-optic medium comprising a binder and having first and second surfaces on opposed sides thereof;

a first release sheet covering the first surface of the layer of solid electro-optic medium; and

a second release sheet covering the second surface of the layer of solid electro-optic medium,

wherein the binder comprises a polyurethane according to claim 7.

22. An article of manufacture for use in forming an electro-optic display, the article of manufacture comprising, in order:

a first release sheet;

a layer of a solid electro-optic medium comprising a binder;

an adhesive layer; and

a second release sheet,

wherein the binder comprises a polyurethane according to claim 7.