Patent ID: 8283395
Filing Date: 2012-10-09
Classification: B01J,C08J,C09B,C09D

Abstract:
1. A method of producing an organic pigment particle dispersion, for use in production of a color filter, which comprises: dissolving an organic pigment comprising a diketopyrrolopyrrole compound into a good solvent to form a solution, mixing the solution with a poor solvent for the organic pigment, the poor solvent being compatible with the good solvent, to prepare a first aqueous dispersion in which organic pigment particles having a number average particle diameter of 1 μm or less are dispersed, concentrating the first aqueous dispersion by at least one of the following (a) to (d): (a) adding an extraction solvent to the first aqueous dispersion to extract the organic pigment particles into an extraction solvent phase; (b) filtering the first aqueous dispersion through a filter; (c) sedimenting the organic pigment particles of the first aqueous dispersion by centrifugal separation; and (d) drying a solvent of the first aqueous dispersion under heat or reduced pressure; to form a concentrated liquid containing the organic pigment particles, wherein the concentrated liquid has a pigment concentration 100 to 1000 times higher than the pigment concentration in the first aqueous dispersion, and mixing the concentrated liquid with an organic medium and a polymer dispersant having a weight average molecular weight of 1,000 or more and having an acidic group, to form a second organic dispersion, suitable for a color filter coating liquid, which contains the organic medium and the organic pigment particles therein.