Microcapsule composition for electrophoretic displays
View Patent ↗The present invention provides: a microcapsule composition for electrophoretic displays; a production process for the microcapsule composition for the electrophoretic displays; a production process for a sheet for the electrophoretic displays; and a handling method for microcapsules for the electrophoretic displays; wherein the microcapsule composition contains microcapsules and, when used for the electrophoretic displays, can make them as excellent as conventional in various performances (e.g. longtime stability of displaying, respondability of displaying, contrast, and number of times of display rewritability) and, particularly above all, can make the electrophoretic displays exhibit a very high performance as to the contrast. The present invention composition is a composition used for preparation of a coating liquid and comprises an aqueous medium and microcapsules for the electrophoretic displays, wherein the microcapsules include a shell and a dispersion that is capsuled in the shell, wherein the dispersion includes a solvent and electrophoretic fine particles that are dispersed in the solvent; with the composition being characterized by: being a product as obtained without involving the step of drying the microcapsules; and having a microcapsule content of 30 to 80 weight %.
1. A production process for a microcapsule composition for electrophoretic displays, wherein the microcapsule composition includes an aqueous medium and microcapsules for the electrophoretic displays, wherein the microcapsules include a shell and an electrophoretic fine particle dispersion that is capsuled in the shell, wherein the electrophoretic fine particle dispersion includes a solvent and electrophoretic fine particles that are dispersed in the solvent;
with the production process comprising:
a dispersing step of dispersing the electrophoretic fine particles into the solvent to obtain the electrophoretic fine particle dispersion;
a microcapsuling step of capsuling the electrophoretic fine particle dispersion into the shell in the presence of the aqueous medium, thereby obtaining a preparation liquid including the microcapsules and the aqueous medium, the preparation liquid having a microcapsule concentration of not more than 15 weight %,
a wet classification step of treating the preparation liquid to classify the microcapsules, and
a concentration step of reducing the aqueous medium from a dispersion resultant from the classification step, thereby concentrating the dispersion and forming the microcapsule composition,
wherein:
the composition having a microcapsule content of 30 to 80 weight % is obtained without involving the step of drying the microcapsules.
2. The production process of claim 1 , wherein the microcapsules have a shell thickness in the range of 0.1 to 5 μm.
3. The production process of claim 1 , wherein the microcapsules have a volume-average particle diameter of 30 to 150 μm and not less than 80% by volume of the microcapsules being present within the particle diameter range of ±40% of the maximum-peak particle diameter around the maximum-peak particle diameter.