Electrophoretic core-shell particles having an organic pigment core and a shell with a thin metal oxide layer and a silane layer

Patent metadata

Field	Value
Publication number	US-12189259-B2
Application number	US-202418615220-A
Country	US
Kind code	B2
Filing date	Mar 25, 2024
Priority date	Feb 6, 2020
Publication date	Jan 7, 2025
Grant date	Jan 7, 2025

Abstract

An electrophoretic medium comprises a plurality of core-shell particles and a non-polar fluid. The core-shell particles comprise an organic pigment particles core and a shell comprising a metal oxide layer and a silane layer. The metal oxide layer may have a thickness of 0.4 to 2 nm. It may be formed using a fluidized bed reactor by inserting the organic pigment into the reactor as a powder bed, contacting the powder bed with a gaseous stream comprising a metal oxide precursor and an inert gas, and contacting the powder bed with a gaseous stream of a reagent and an inert gas. The silane layer is formed from a silane compound comprising a first functional group, wherein the first functional group reacts with the metal oxide.

First claim

We claim:

1. A method of manufacturing of an electrophoretic medium, the electrophoretic medium comprising a plurality of a first type of core-shell particles and a non-polar fluid, each of the plurality of the first type of the core-shell particles comprising a core comprising an organic pigment and a shell comprising a metal oxide layer and a silane layer, wherein the method comprises the steps of:
providing organic pigment particles;
introducing the organic pigment particles into a fluidized bed reactor as a powder bed;
contacting the powder bed with a gaseous stream comprising an inert gas and a precursor of metal oxide;
contacting the powder bed with a gaseous stream comprising a reagent that reacts with the metal oxide precursor to form a metal oxide, wherein the reagent is selected from the group consisting of water, oxygen, ozone, or mixtures thereof;
reacting the organic pigment particles having a metal oxide layer with a silane compound in an organic solvent to form a silane layer, wherein the silane compound comprises a first functional group, a second functional group, and a third functional group, wherein the first functional group reacts with the metal oxide to form organic pigment particles comprising a metal oxide layer and a silane layer;
combining the plurality of core-shell particles and the non-polar fluid.

2. The method of manufacturing of an electrophoretic medium of claim 1 , wherein the silane compound further comprises a second functional group, wherein the second functional group is selected from the group consisting of a halogenated alkyl group, an aryl group, a hydroxy group, a carboxy group, a sulfate group, a sulfonate group, a phosphate group, a phoshonic group, an amine group, a quaternary ammonium group, a dimethylsiloxane group, an ester group, an amide group, and ethylenimine group.

3. The method of manufacturing of an electrophoretic medium of claim 1 further comprising, before the step of combining the plurality of core-shell particles and non-polar fluid, a step of reacting the organic pigment particles having a metal oxide layer and a silane layer with a monomer or a macromonomer comprising a fourth functional group to form a plurality of core-shell particles, wherein the third functional group of the silane reacts with the fourth functional group of the monomer or macromonomer.

4. The method of manufacturing of an electrophoretic medium of claim 1 , wherein the metal oxide layer comprises aluminum oxide, silica, titanium dioxide, zirconium oxide, zinc oxide or mixtures thereof.

5. The method of manufacturing of an electrophoretic medium of claim 1 , wherein the first functional group is selected from the group consisting of alkoxy, alkylamino, halide, hydrogen, and hydroxy.

6. The method of manufacturing of an electrophoretic medium of claim 1 , wherein the metal oxide precursor is selected from the group consisting of trimethylaluminum, triethylaluminum, dimethylaluminum chloride, diethylaluminum chloride, trimethoxyaluminum, triethoxyaluminum, dimethylaluminum propoxide, aluminum triisopopoxide, tributoxy aluminum, tris(dimethylamino) aluminum, tris(diethylamino) aluminum, tris(propylamino) aluminum, aluminum trichloride, trichlorosilane, hexachlorodisilane, silicon tetrachloride, tetramethoxysilane, tetraethoxysilane, tris(tert-pentoxy)silanol, tetraisocyanatesilane, silicon tertrachoride, tris(methylamino)silane, tris(ethylamino)silane, titanium tetrachloride, titanium tetraiodide, tetramethoxy titanium, tetraethoxy titanium, titanium isopropoxide, tetrakis(methylamino) titanium, tetrakis(ethylamino) titanium, dimethyl zinc, diethyl zinc, methyl zinc isopropoxide, zirconium tetrachloride, zirconium tetraiodide, tetramethoxy zirconium, tetraethoxy zirconium, tetraisopropoxy zirconium, tetrabutoxy zirconium, tetrakis(methylamino) zirconium, tetrakis(ethylamino) zirconium, and mixtures thereof.

7. The method of manufacturing of an electrophoretic medium of claim 1 , wherein the metal oxide layer has thickness of from about 0.5 nm to about 2 nm.

8. The method of manufacturing of an electrophoretic medium of claim 1 , wherein the third functional group of the silane compound is selected from the group consisting of epoxy, vinyl, styrene, acryloyl, methacryloyl, methacryloxyakyl, amino, hydroxy, carboxy, alkoxy group, and chloride.

9. The method of manufacturing of an electrophoretic medium of claim 3 , wherein the fourth functional group of the monomer or macromonomer is selected from the group consisting of vinyl, styrene, acryloyl, methacryloyl, methacryloxyakyl, epoxy, amino, hydroxy, carboxy, and chloride.

10. The method of manufacturing of an electrophoretic medium of claim 1 , wherein the organic pigment is selected from the group consisting of an azo pigment, a phthalocyanine pigment, a quinacridone pigment, a perylene pigment, a diketopyrrolopyrrole pigment, a benzimidazolone pigment, an isoindoline pigment, an anthranone pigment, an indanthrone pigment, a carbon black pigment, a rhodamine pigment, a benzinamine pigment, a carbon black pigments, and mixtures therein.

11. The method of manufacturing of an electrophoretic medium of claim 1 , wherein the organic pigment is selected from the group consisting of C.I. Pigment Blue 15, 15:1, 15:2, 15:3, 15:4 15:6, 60, and 79; Pigment Red 2, 4, 5, 9, 12, 14, 38, 48:2, 48:3, 48:4, 52:2, 53:1, 57:1, 81, 112, 122, 144, 146, 147, 149, 168, 170, 176, 177, 179, 184, 185, 187, 188, 208, 209, 210, 214, 242, 254, 255, 257, 262, 264, 282, and 285; C.I. Pigment Violet 1, 19, 23, and 32, C.I. Pigment Yellow 1, 3, 12, 13, 14, 15, 16, 17, 73, 74, 81, 83, 97, 109, 110, 111, 120, 126, 127, 137, 138, 139, 150, 151, 154, 155, 174, 175, 176, 180, 181, 184, 191, 194, 213 and 214; C.I. Pigment Green 7, and 36; C.I. Pigment Black 1, and 7; C.I. Pigment Brown 25, 32, 41; Pigment Orange 5, 13, 34, 36, 38, 43, 61, 62, 64, 68,67, 72, 73, and 74, and mixtures thereof.

Assignees

• E Ink Corp

Inventors

• Anseth Jay William
• Macdonald Brandon
• Breen Craig Alan

Classifications

• C09B67/0007

  with inorganic coatings · CPC title

• G02F2202/28

  Adhesive materials or arrangements · CPC title

• G02F2001/1678

  characterised by the composition or particle type · CPC title

• G02F2202/022

  polymeric · CPC title

• G02F1/167

  by electrophoresis · CPC title