Electrophoretic particle, process for its production, and its use
View Patent ↗An electrophoretic particle including: a pigment particle having an average particle diameter of 1 μm or smaller; and a polymer layer having an average thickness of 1 to 500 nm formed on a surface of the pigment particle, wherein 50% or higher of an entire surface of the pigment particle is coated with the polymer layer. The electrophoretic particle can be produced by radical polymerization using a polymerization initiator in a state where a pigment particle and monomer components are present in a solvent. The electrophoretic particle can be used in a microcapsule and a sheet for electrophoretic display, as well as an electrophoretic display device and an electronic equipment.
1. An electrophoretic particle comprising:
a pigment particle having an average particle diameter of 1 μm or smaller; and
a polymer layer having an average thickness of 1 to 500 nm formed on a surface of the pigment particle, wherein 50% or higher of an entire surface of the pigment particle is coated with the polymer layer.
2. A process for producing an electrophoretic particle, comprising steps of:
carrying out radical polymerization using a polymerization initiator in a state where a pigment particle and monomer components are present in a solvent to give an electrophoretic particle comprising a pigment particle and a polymer layer formed on a surface of the pigment particle, wherein:
the pigment particle is a pigment particle having an average particle diameter of 1 μm or smaller which has been mixed with a coupling agent having a polymerizable reactive group prior to the radical polymerization;
an amount of the coupling agent having a polymerizable reactive group to be used is 0.1% to 5% by weight, based on an amount of the pigment particle to be used;
the solvent comprises a hydrophilic organic solvent and water, and a ratio of the water to be added is 10% to 30% by weight, based on a total amount of the solvent;
the monomer components comprise a hydrophilic monomer and a hydrophobic monomer, and a ratio of the hydrophilic monomer to be added is 5% to 30% by weight, based on a total amount of the monomer components; and
the polymerization initiator is water soluble, and a concentration of the monomer components is 0.5% to 5% by weight, based on a total amount of the solvent and the monomer components.
3. A dispersion for electrophoretic display, comprising a dispersing medium and an electrophoretic particle according to claim 1 dispersed in the dispersing medium.
4. A microcapsule for electrophoretic display, comprising a capsule shell and a dispersion for electrophoretic display according to claim 3 encapsulated in the capsule shell.
5. A sheet for electrophoretic display, comprising:
a substrate sheet having a substrate film and an electrically conductive layer formed on the substrate film; and a layer containing microcapsules for electrophoretic display according to claim 4 , the microcapsules-containing layer being formed on the electrically conductive layer of the substrate sheet.
6. An electrophoretic display device comprising a data displaying part, wherein the data displaying part comprises a sheet for electrophoretic display according to claim 5 .
7. An electronic equipment comprising a data displaying means, wherein the data displaying means comprises an electrophoretic display device according to claim 6 .