The present invention provides [1] a process for producing a colored fine particle dispersion including the step of subjecting a dispersion including a pigment, a polymerizable monomer, a surfactant, a polymerization initiator and water to emulsion polymerization, the pigment being a pigment having a quinacridone skeleton; the surfactant being an anionic or nonionic surfactant; and the polymerization initiator including an anionic or nonionic azo-based compound, [2] a colored fine particle dispersion including colored fine particles having an average particle size of not less than 10 nm and not more than 300 nm, and [3] a process for producing a water-based ink for ink-jet printing, including the step of mixing the obtained colored fine particle dispersion and an organic solvent B.

Polymer shells similar to those described in U.S. Pat. No. 6,822,782 can be formed on pigment particles by (a) physi-sorping a reagent comprising polymerizable groups on to the pigment particles by treating the particle with a reagent having a polymerizable or polymerization-initiating group, such that the reagent will not desorb from the particle surface when the particle is placed in a hydrocarbon medium; or (b) treating pigment particles bearing nucleophilic groups with a reagent having a polymerizable or polymerization-initiating group, and an electrophilic group, thus attaching the polymerizable or polymerization-initiating groups to the particle surface. The zeta potential of the pigment particles can be varied by a process similar to (b) but using a reagent which does not have a polymerizable or polymerization-initiating group.

Polymer shells similar to those described in U.S. Pat. No. 6,822,782 can be formed on pigment particles by (a) physi-sorping a reagent comprising polymerizable groups on to the pigment particles by treating the particle with a reagent having a polymerizable or polymerization-initiating group, such that the reagent will not desorb from the particle surface when the particle is placed in a hydrocarbon medium; or (b) treating pigment particles bearing nucleophilic groups with a reagent having a polymerizable or polymerization-initiating group, and an electrophilic group, thus attaching the polymerizable or polymerization-initiating groups to the particle surface. The zeta potential of the pigment particles can be varied by a process similar to (b) but using a reagent which does not have a polymerizable or polymerization-initiating group.

Polymer shells similar to those described in U.S. Pat. No. 6,822,782 can be formed on pigment particles by (a) physi-sorping a reagent comprising polymerizable groups on to the pigment particles by treating the particle with a reagent having a polymerizable or polymerization-initiating group, such that the reagent will not desorb from the particle surface when the particle is placed in a hydrocarbon medium; or (b) treating pigment particles bearing nucleophilic groups with a reagent having a polymerizable or polymerization-initiating group, and an electrophilic group, thus attaching the polymerizable or polymerization-initiating groups to the particle surface. The zeta potential of the pigment particles can be varied by a process similar to (b) but using a reagent which does not have a polymerizable or polymerization-initiating group.

Polymer shells similar to those described in U.S. Pat. No. 6,822,782 can be formed on pigment particles by (a) physi-sorping a reagent comprising polymerizable groups on to the pigment particles by treating the particle with a reagent having a polymerizable or polymerization-initiating group, such that the reagent will not desorb from the particle surface when the particle is placed in a hydrocarbon medium; or (b) treating pigment particles bearing nucleophilic groups with a reagent having a polymerizable or polymerization-initiating group, and an electrophilic group, thus attaching the polymerizable or polymerization-initiating groups to the particle surface. The zeta potential of the pigment particles can be varied by a process similar to (b) but using a reagent which does not have a polymerizable or polymerization-initiating group.

Quinacridone pigments that are surface-functionalized with glycidyl methacrylate, maleic anhydride, or 4-methacryloxyethyl trimellitic anhydride to create a functionalized pigment. The functional groups are then activated to bond hydrophobic polymers, thereby coating the pigment with the hydrophobic polymers. The quinacridone pigments can be used for a variety of applications. They are well-suited for use in electro-optic materials, such as electrophoretic media for use in electrophoretic displays.

Quinacridone pigments that are surface-functionalized with glycidyl methacrylate, maleic anhydride, or 4-methacryloxyethyl trimellitic anhydride to create a functionalized pigment. The functional groups are then activated to bond hydrophobic polymers, thereby coating the pigment with the hydrophobic polymers. The quinacridone pigments can be used for a variety of applications. They are well-suited for use in electro-optic materials, such as electrophoretic media for use in electrophoretic displays.

Provided is a quinacridone solid solution pigment that develops a color more clearly than a conventional pigment does. The quinacridone solid solution pigment includes at least two kinds of quinacridone-based pigments including unsubstituted quinacridone and 2,9-dialkylquinacridone. When a diffraction peak intensity at a diffraction angle 2? of 5.9??0.2? and a diffraction peak intensity at a diffraction angle 2? of 6.4??0.2?, which are obtained by X-ray diffractometry, are represented by T1 and T2, respectively, T1 and T2 satisfy T2/(T1+T2)?0.13.

Provided is a quinacridone solid solution pigment that develops a color more clearly than a conventional pigment does. The quinacridone solid solution pigment includes at least two kinds of quinacridone-based pigments including unsubstituted quinacridone and 2,9-dialkylquinacridone. When a diffraction peak intensity at a diffraction angle 2? of 5.9??0.2? and a diffraction peak intensity at a diffraction angle 2? of 6.4??0.2?, which are obtained by X-ray diffractometry, are represented by T1 and T2, respectively, T1 and T2 satisfy T2/(T1+T2)?0.13.

A method for producing a halogenated organic pigment comprising a halogenation step of halogenating an organic pigment with a halogenating agent, wherein the halogenating agent comprises one or more N-haloimide compounds selected from the group consisting of trichloroisocyanuric acid, a metal salt of dichloroisocyanuric acid, tribromoisocyanuric acid, and a metal salt of dibromoisocyanuric acid. According to the present invention, a method for producing a halogenated organic pigment which does not use high toxic raw materials, does not generate a large amount of unfavorable by-products such as hydrogen halide gas and succinimide, and is excellent in terms of safety and productivity can be provided.