Colored composite microparticles, process for producing the colored composite microparticles, colorant, color filter and ink for ink-jet printing

Abstract

There are provided colored composite microparticles having a fine primary particle diameter and exhibiting a high tinting strength, an excellent dispersibility and an excellent light fastness; a process for producing the colored composite microparticles; and a dispersion of the colored composite microparticles. The colored composite microparticles are composite particles comprising silica and an organic pigment in which the silica is enclosed in the organic pigment and contained in an amount of 0.001 to 9% by weight (calculated as Si) based on the weight of the composite particles. The coloring composition for color filters is prepared by dispersing a colorant for color filters comprising the colored composite microparticles in a coloring composition base material, whereas the ink for ink-jet printing is prepared by dispersing a colorant for inks for ink-jet printing comprising the colored composite microparticles in an ink base solution. The colored composite microparticles have a high tinting strength and are excellent in dispersibility and light fastness, and therefore, can be suitably used in various applications such as ordinarily used paints, printing inks, etc., irrespective of an aqueous system or a solvent system.

Description

CROSS REFERENCES TO RELATED APPLICATIONS[0001]This is a continuation-in-part application of International Application No. PCT / JP2006 / 317543, filed 5 Sep. 2006, which designated the US and claims benefit of JP 2005-262254, filed 9 Sep. 2005, JP 2006-172462, filed 22 Jun. 2006 and JP 2006-194645, filed 14 Jul. 2006, the entire contents of each of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to colored composite microparticles, a dispersion containing the colored composite microparticles, a process for producing the colored composite microparticles, a colorant for color filters, a coloring composition for color filters containing the colorant, a color filter, a colorant for inks for ink-jet printing, and an ink for ink-jet printing. More particularly, the present invention relates to colored composite microparticles having a fine primary particle diameter, and exhibiting a high tinting strength, an excellent dispersibility an...

AI Technical Summary

Benefits of technology

[0030]The present invention has been attained in view of the above problems. An object of the present invention is to provide colored composite microparticles having a fine primary particle diameter and exhibiting a high tinting strength, an excellent dispersibility and an excellent light fastness, a process for producing the colored composite microparticles and a dispersion prepared by dispersing the colored composite microparticles in a solvent. A further object of the present invention is to provide a colorant for color filters which has a fine primary particle diameter, exhibits a high tinting strength, and is excellent in light fastness, heat resistance and dispersibility in vehicles, as well as a coloring composition for color filters and a color filter. A still further object of the present invention is to provide a colorant for inks for ink-jet printing which has a fine primary particle diameter and a uniform particle size distribution, and exhibits a high tinting strength and an excellent light fastness, as well as an ink for ink-jet printing.

Problems solved by technology

However, there is a tendency that when the particle size of the pigment is lessened, the pigment is deteriorated in light fastness and heat resistance.

Thus, such a colorant capable of satisfying these contradictory properties at the same time has not been obtained until now.

Since the resultant organic pigment has a ζ potential close to zero, it may be difficult to attain an electrostatic repulsion effect thereof in vehicles.

Therefore, the organic pigment may fail to exhibit a good dispersibility and a good dispersion stability in vehicles.

In the method as described in Japanese Patent Application Laid-open (KOKAI) No. 2002-356625 in which an organic pigment is allowed to adhere onto the surface of white inorganic particles through a gluing agent such as an alkoxysilane, as described in Comparative Examples below, since the white inorganic particles such as silica particles are used as core particles, it may be difficult to attain a high tinting strength identical to or higher than that of the raw organic pigment adhered thereonto.

In addition, since silica is completely dissolved, the resultant colored fine particles tend to have a ζ potential close to zero, and therefore, hardly exhibit a good electrostatic repulsion effect in vehicles, so that it may be difficult to attain a good dispersibility and a good dispersion stability thereof in vehicles.