A technical problem of the present invention is to provide a condensed polycyclic organic pigment having excellent dispersion properties and dispersion stability. More specifically, the technical problem of the present invention is to provide a condensed polycyclic organic pigment in which a practically sufficient viscosity is achieved in terms of both the initial viscosity of a base ink and the viscosity over time of a base ink when used in the printing ink application. As a result of thorough studies on the surface state of organic pigment particles and interaction among components constituting a printing ink, it has been found that the technical problem can be solved by using a polyvalent metal inorganic salt in a condensed polycyclic organic pigment, thus accomplishing the present invention.

A water-based ink for ink-jet recording, includes: a solid solution of a quinacridone pigment including C.I. Pigment Violet 19 and C.I. Pigment Red 122, an azo pigment including C.I. Pigment Red 48:3, and water.

A water-based ink for ink-jet recording, includes: a solid solution of a quinacridone pigment including C.I. Pigment Violet 19 and C.I. Pigment Red 122, an azo pigment including C.I. Pigment Red 48:3, and water.

A water-based ink for ink-jet recording includes: a solid solution of a quinacridone pigment including C.I. Pigment Red 122 and C.I. Pigment Violet 19; an azo pigment including C.I. Pigment Red 146; and water. Mass ratio (Q:A) of a content amount (Q) of the solid solution of the quinacridone pigment to a content amount (A) of the azo pigment in an entire amount of the water-based ink is in a range of 9:1 to 1:9.

The present invention relates to a technique for providing a quinacridone solid solution pigment, by which a quinacridone solid solution pigment that allows a colored product to have high chroma and a properly yellowish hue, and suitably, that has a controlled particle diameter and has the above-described, desired hue can be obtained. The present invention provides a method for producing a quinacridone solid solution pigment, wherein a diarylaminoterepththalic acid and a dialkylarylaminoterephthalic acid are subjected to a co-cyclization reaction in polyphosphoric acid, thereby obtaining a water-containing crude quinacridone solid solution such that water is contained in a solid solution having a mass ratio of unsubstituted quinacridone to a 2,9-dialkylquinacridone of 85:15 to 60:40; the water-containing crude quinacridone solid solution obtained above is dried in a drying step, thereby obtaining a powdery, crude quinacridone solid solution having a water content of less than 1%; and the powdery, crude quinacridone solid solution is heated in a liquid medium that does not dissolve the crude quinacridone solid solution in a pigmentation step, and the present invention also provides a pigment dispersion liquid and an inkjet ink each containing the obtained quinacridone solid solution pigment.

The present invention relates to a technique for providing a quinacridone solid solution pigment, by which a quinacridone solid solution pigment that allows a colored product to have high chroma and a properly yellowish hue, and suitably, that has a controlled particle diameter and has the above-described, desired hue can be obtained. The present invention provides a method for producing a quinacridone solid solution pigment, wherein a diarylaminoterepththalic acid and a dialkylarylaminoterephthalic acid are subjected to a co-cyclization reaction in polyphosphoric acid, thereby obtaining a water-containing crude quinacridone solid solution such that water is contained in a solid solution having a mass ratio of unsubstituted quinacridone to a 2,9-dialkylquinacridone of 85:15 to 60:40; the water-containing crude quinacridone solid solution obtained above is dried in a drying step, thereby obtaining a powdery, crude quinacridone solid solution having a water content of less than 1%; and the powdery, crude quinacridone solid solution is heated in a liquid medium that does not dissolve the crude quinacridone solid solution in a pigmentation step, and the present invention also provides a pigment dispersion liquid and an inkjet ink each containing the obtained quinacridone solid solution pigment.

Disclosed herein are compositions (e.g., pigment dispersions or ink compositions such as inkjet ink compositions) comprising at least one quinacridone magenta pigment and at least one synergist selected from compounds (A) and (B) having the following structures, wherein each n is an integer independently ranging from 1 to 4, and R.sub.1-R.sub.3 are each independently selected from H, CH.sub.3, Cl, and F,

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The present disclosure is drawn to aqueous pigment co-dispersions. The co-dispersions include self-dispersed pigment with a chemically modified surface; released surface moieties from the self-dispersing pigment; pigment powder having the released surface moieties associated with pigment powder surfaces; polymeric dispersant; and water.

The present disclosure is drawn to aqueous pigment co-dispersions. The co-dispersions include self-dispersed pigment with a chemically modified surface; released surface moieties from the self-dispersing pigment; pigment powder having the released surface moieties associated with pigment powder surfaces; polymeric dispersant; and water.

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.