Method of making electrophoretic dispersion

Patent metadata

Field	Value
Publication number	US-2016333185-A1
Application number	US-201615224964-A
Country	US
Kind code	A1
Filing date	Aug 1, 2016
Priority date	Nov 5, 2010
Publication date	Nov 17, 2016
Grant date	—

Abstract

The present invention is directed to methods of making an electrophoretic dispersion comprising pigment particles dispersed in a solvent or solvent mixture, wherein said pigment particles comprises at least one polymer chain comprising a terminal thiocarbonylthio group, attached to the particle surface. The invention also relates to pigment particles suitable for use in an electrophoretic dispersion and methods for their preparation through a RAFT polymerization technique.

First claim

What is claimed is:

1 . A method of preparing pigment particles comprising polymer chains attached to the pigment particle surface, comprising:
(a) reacting pigment particles with a Reversible Addition-Fragmentation chain Transfer (RAFT) reagent bearing an anchoring group; and (b) performing RAFT polymerization in the presence of a free radical initiator, thereby causing the pigment particles to attach to polymer chains comprising:
an outer polymer layer formed from first monomers, the outer polymer layer being compatible with a hydrocarbon solvent,
an inner polymer layer formed from second monomers different from the first monomers, wherein the second monomers comprise a charged functional group to provide charge to the pigment particles, and
a terminal thiocarbonylthio group attached to the outer polymer layer.

2 . The method of claim 1 , wherein the terminal thiocarbonylthio group comprises an optionally substituted alkyl, an optionally substituted aryl, an optionally substituted alkylaryl, or an optionally substituted arylalkyl group.

3 . The method of claim 1 , wherein the first monomer is selected from the group consisting of styrene, methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, vinyl pyridine, n-vinyl pyrrolidone, 2-hydoxyethyl acrylate, 2-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, vinylbenzylaminoethylaminopropyl-trimethoxysilane, methacryloxypropyltrimethoxysilane, acrylic acid, methacrylic acid and vinyl phosphoric acid, and
the second monomer is selected from the group consisting of lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hexyl acrylate, hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-octadecyl acrylate, and n-octadecyl methacrylate.

4 . The method of claim 1 , further comprising mixing the pigment particles with a reagent comprising both the free radical initiator and the anchoring group.

5 . The method of claim 1 , wherein steps (a) and (b) are initiated with different free radical initiators.

6 . The method of claim 1 , further comprising modifying the surface of the pigment particles to introduce a vinyl functional group.

7 . The method of claim 1 , wherein the resulting particle comprises a molar ratio of first monomers to second monomers of between 10:1 and 1:1.

8 . The method of claim 1 , wherein the anchoring group is a carboxylic acid group, a primary amino group, a secondary amino group, a hydroxyl group, a mecapto group, or a silane group.

Assignees

• E Ink California Llc

Inventors

• Li Yu
• Du Hui
• Liu Yayong
• Gu Haiyan
• Zang Hongmei

Classifications

• G02F2001/1678

  characterised by the composition or particle type · CPC title

• C09C1/56

  Treatment of carbon black {; Purification} · CPC title

• G02F1/167

  by electrophoresis · CPC title

• C08F292/00

  Macromolecular compounds obtained by polymerising monomers on to inorganic materials · CPC title

• C09C1/3676 Primary

  Treatment with macro-molecular organic compounds · CPC title