Electro-optic display and materials for use therein

• US 7,986,450 B2
• Filed: 01/12/2009
• Issued: 07/26/2011
• Est. Priority Date: 09/22/2006
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated, Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Miller, David D., Fazel, Shafiq N., Cao, Lan, Webber, Richard M.
• Primary Examiner(s): Lester; Evelyn A.
• Application Number:
  US12/351,880
• Publication Number:
  US 20090237773A1
• Time in Patent Office: 925 Days
• Field of Search: 359/245, 359/290, 359/296, 428/844.5, 428/844.71, 428/844.8, 345/107, 156/250, 156/257, 528/75, 528/76
• US Class Current: 359/245
• CPC Class Codes: C08G 18/0823 containing carboxylate salt groups or groups forming them
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• 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 18/4018 Mixtures of compounds of group C08G18/42 with compounds of group C08G18/48
• CPC Class Codes: C08G 18/4277 Caprolactone and/or substituted caprolactone
• CPC Class Codes: C08G 18/4825 Polyethers containing two hydroxy groups C08G18/4833 - C08G18/5096 take precedence
• 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
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: Y10T 156/1052 with cutting, punching, tearing or severing
• CPC Class Codes: Y10T 156/1064 Partial cutting [e.g., grooving or incising]

Abstract

A polyurethane formed from an isocyanate, a polyether diol and a polyester diol, the polyester diol having a molecular weight less than about 2000, or 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 molar ratio of polyether diol to polyester diol being in the range of from about 1:9 to about 9:1. The polyurethane is useful as a lamination adhesive in electro-optic displays, and in components used to form such displays.

Claims

1. A polyurethane formed from an isocyanate, a polyether diol and a polyester diol, the polyester diol having a molecular weight less than about 2000, or 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 molar ratio of polyether diol to polyester diol being in the range of from about 1:

9 to about 9;

1.

2. A polyurethane according to claim 1 wherein the molar ratio of polyether diol to polyester diol is in the range of from about 1:

4 to about 4;

1.

3. A polyurethane according to claim 1 wherein the polyester diol is a polycaprolactone diol having a molecular weight less than about 1500.

4. A polyurethane according to claim 1 wherein the polyester diol is a polycaprolactone diol comprising two polycaprolactone segments connected by a bending group, each of the polycaprolactone segments having a molecular weight not greater than about 1500.

5. A polyurethane according to claim 1 wherein the isocyanate is 4,4′

-methylenebis(cyclohexyl isocyanate).

6. A polyurethane according to claim 1 wherein the polyether diol is a poly(propylene oxide) diol.

7. A polyurethane according to claim 1 wherein the polyether diol has a molecular weight in the range of from about 1000 to about 3000.

8. A polyurethane according to claim 1 having an isocyanate:

hydroxyl ratio of less than about 1.3.

9. A polyurethane according to claim 1 having a crossover temperature in the range of from about 10 to about 90°

C. at 1 Hz.

10. A polyurethane according to claim 9 having a crossover temperature in the range of from about 40 to about 80°

C. at 1 Hz.

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

12. A sub-assembly for use in constructing an electro-optic display, the sub-assembly comprising a layer of a solid electro-optic material and a layer of lamination adhesive adhered to the layer of electro-optic material, the layer of lamination adhesive comprising a polyurethane according to claim 1.

13. An electro-optic display comprising a sub-assembly according to claim 12 and at least one electrode arranged to apply an electric field to the layer of electro-optic material.

14. 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 13.

15. A sub-assembly according to claim 12 further comprising:

a light-transmissive electrically-conductive layer on the opposed side of the layer of electro-optic material from the layer of lamination adhesive; and

a release sheet on the opposed side of the layer of lamination adhesive from the layer of electro-optic material.

16. A sub-assembly according to claim 12 further comprising:

a second adhesive layer on the opposed side of the layer of electro-optic material from the layer of lamination adhesive; and

a release sheet disposed on the opposed side of the second adhesive layer from the layer of electro-optic material.

17. A sub-assembly according to claim 12 further comprising:

on the opposed side of the layer of lamination adhesive from the layer of electro-optic material, at least one of a light-transmissive protective layer and a light-transmissive electrically-conductive layer; and

a release sheet on the opposed side of the layer of electro-optic material from the layer of lamination adhesive.

18. A sub-assembly according to claim 12 further comprising first and second release sheets covering the exposed surfaces of the layer of electro-optic material and the layer of lamination adhesive.