Colored electrophoretic displays

Patent metadata

Field	Value
Publication number	US-11460722-B2
Application number	US-202016867969-A
Country	US
Kind code	B2
Filing date	May 6, 2020
Priority date	May 10, 2019
Publication date	Oct 4, 2022
Grant date	Oct 4, 2022

Abstract

An electrophoretic medium includes a fluid, a plurality of light scattering charged particles having a first polarity, and a first, second, and third set of particles, each set having a color different from each other set. The first and second particles may have a second polarity opposite to the first polarity, and the mobility of the third set of particles is less than half of the mobility of the light scattering particles, the first set of charged particles, and the second set of charged particles.

First claim

The invention claimed is:

1. An electrophoretic medium comprising:
a fluid;
a plurality of light scattering charged particles having a first polarity; and
a first, second, and third set of charged particles, each set having a color different from each other set,
wherein the first and second particles have a second polarity opposite to the first polarity, and
the third particles are composite particles comprising a core pigment and a polymer shell, wherein:
(a) a mass fraction of the polymer shell to the composite particle is at least 20 wt % to at most 50 wt %; and
(b) the polymer shell comprises:
(I) a first monomeric unit derived from a first precursor of Formula (1):
CH 2 ═C(R 1a )C(O)R 2   (1)

wherein: R 1a is —H or —CH 3 ; R 2 is —OR 3 , —NHR 3 , or —NR 3 2 ; R 3 is C 1-6 alkyl, C 1-6 heteroalkyl, C 3-10 cycloalkyl, C 3-10 heterocycloalkyl, C 6-14 aryl, C 5-14 heteroaryl, or any combination thereof, each of which is optionally substituted one more times by groups selected independently from R 4 ;
R 4 is a C 1-6 alkyl, —OH, C 1-6 alkoxy, —NH 2 , —NH(C 1-6 alkyl), —N(C 1-6 alkyl) 2 , C 1-6 haloalkyl, or C 1-6 haloalkoxy;
(II) a second monomeric unit derived from a second precursor of Formula (2):
CH 2 ═C(R 1b )C(O)R 5   (2)

wherein: R 1b is —H or —CH 3 ; R 5 is —OR 6 , —NHR 6 , or —NR 6 2 ; R 6 is C 1-6 alkyl, C 1-6 heteroalkyl, C 3-10 cycloalkyl, C 3-10 heterocycloalkyl, C 6-14 aryl, C 5-14 heteroaryl, or any combination thereof, each of which is substituted one or more times by groups selected independently from R 7 ; R 7 is a halogen, —CN, —NO 2 , —S(O)—, or —S(O) 2 —.

2. The electrophoretic medium of claim 1 , wherein R 3 is C 1-6 alkyl, C 6-14 aryl, or any combination thereof, each of which is optionally substituted one or more times by groups selected independently from R 4 ; and R 4 is a C 1-6 alkyl, or C 1-6 alkoxy.

3. The electrophoretic medium of claim 1 , wherein R 2 is —OR 3 , and R 3 is C 1-6 alkyl or C 6-14 aryl, the C 6-14 aryl optionally substituted one or more times by groups selected independently from R 4 ; and R 4 is C 1-6 alkoxy.

4. The electrophoretic medium of claim 1 , wherein R 6 is C 1-6 alkyl and R 7 is a halogen.

5. The electrophoretic medium of claim 1 , wherein R 5 is —OR 6 , R 6 is C 1-6 alkyl substituted at least three times by R 7 , and R 7 is —F.

6. The electrophoretic medium of claim 1 , wherein the first precursor is selected from the group consisting of methyl methacrylate, methoxyphenyl methacrylate, and N,N-di-isopropylacrylamide.

7. The electrophoretic medium according to claim 1 , wherein the second precursor is trifluoroethyl methacrylate (TFEM).

8. A front plane laminate, double release sheet, inverted front plane laminate or electrophoretic display comprising an electrophoretic medium according to claim 1 .

9. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising an electrophoretic display according to claim 8 .

10. An electrophoretic medium comprising,
a fluid;
a plurality of light scattering charged particles having a first polarity; and
a first, second, and third set of charged particles, each set having a color different from each other set,
wherein the first and second particles have a second polarity opposite to the first polarity, and the magnitude of the electrophoretic mobility of the third set of particles is less than half of the magnitude of the electrophoretic mobility of the light scattering particles, the first set of charged particles, and the second set of charged particles.

11. The electrophoretic medium according to claim 10 , wherein electrophoretic mobility is measured from particle zeta potentials.

12. The electrophoretic medium according to claim 11 , wherein the third set of particles has a zeta potential greater than or equal to −20 mV and less than or equal to 20 mV.

13. The electrophoretic medium according to claim 10 , wherein electrophoretic mobility is measured from particle charge-to-mass ratios.

14. The electrophoretic medium according to claim 10 , wherein electrophoretic mobility is measured from particle dispersion conductivity measurements.

15. A front plane laminate, double release sheet, inverted front plane laminate or electrophoretic display comprising an electrophoretic medium according to claim 10 .

16. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising an electrophoretic display according to claim 15 .

17. An electrophoretic medium comprising,
a fluid;
a plurality of light scattering charged particles having a first polarity; and
a first, second, and third set of charged particles, each set having a color different from each other set,
wherein the first and second particles have a second polarity opposite to the first polarity, and
the third particles are composite particles comprising a core pigment and a polymer shell, wherein:
(a) a mass fraction of the polymer shell to the composite particle is at least 20 wt % to at most 50 wt %, and
(b) the polymer shell comprises:
(I) a first monomeric unit derived from a first precursor of Formula (1):
CH 2 ═C(R 1a )C(O)R 2   (1)

wherein: R 1a is —H or —CH 3 ; R 2 is —OR 3 , —NHR 3 , or —NR 3 2 ; R 3 is C 1-6 alkyl, C 1-6 heteroalkyl, C 3-10 cycloalkyl, C 3-10 heterocycloalkyl, C 6-14 aryl, C 5-14 heteroaryl, or any combination thereof, each of which is optionally substituted one more times by groups selected independently from R 4 ,
R 4 is a C 1-6 alkyl, —OH, C 1-6 alkoxy, —NH 2 , —NH(C 1-6 alkyl), —N(C 1-6 alkyl) 2 , C 1-6 haloalkyl, or C 1-6 haloalkoxy;
(II) a second monomeric unit derived from a styrene optionally substituted one or more times by groups selected independently from C 1-6 alkyl, C 1-6 alkoxy, —NH(C 1-6 alkyl), —N(C 1-6 alkyl) 2 , and halogen.

18. The electrophoretic medium of claim 17 , wherein R 3 is C 1-6 alkyl, C 6-14 aryl, or any combination thereof, each of which is optionally substituted one or more times by groups selected independently from R 4 ; and R 4 is a C 1-6 alkyl, or C 1-6 alkoxy.

19. The electrophoretic medium of claim 17 , wherein R 2 is —OR 3 , and R 3 is C 1-6 alkyl or C 6-14 aryl, the C 6-14 aryl optionally substituted one or more times by groups selected independently from R 4 ; and R 4 is C 1-6 alkoxy.

20. The electrophoretic medium according to claim 17 , wherein in third particles a mass fraction of the polymer shell to the composite particle is at least 25 wt % to at most 40 wt %.

21. The electrophoretic medium according to claim 17 , wherein the mass fraction of the polymer shell to the composite particle is measured by thermogravimetric analysis (TGA).

22. A front plane laminate, double release sheet, inverted front plane laminate or electrophoretic display comprising an electrophoretic medium according to claim 17 .

23. An electronic book reader, portable computer, tablet computer, cellular telephone, smart card, sign, watch, shelf label or flash drive comprising an electrophoretic display according to claim 22 .

Assignees

• E Ink Corp

Inventors

• Telfer Stephen J
• BZOWEJ Eugene
• Crounse Kenneth R
• Marshall John L
• Macdonald Brandon
• Wu Ziyan
• Yezek Lee

Classifications

• G09G3/344

  based on particles moving in a fluid or in a gas, e.g. electrophoretic devices (electrophoretic devices per se G02F1/167) · CPC title

• G02F1/0018 Primary

  Electro-optical materials · CPC title

• G02F2001/1678

  characterised by the composition or particle type · CPC title

• C09K9/02

  Organic tenebrescent materials · CPC title

• G02F1/167 Primary

  by electrophoresis · CPC title