Dic Corporation

Dic Corporation (tokyo)

Yukihiko Kawaharada

Yoshinosuke Shimamura

Takaaki Nabe

Shinichi Okada

Hiroyuki Buei

Soetrisno Misawa

The present invention provides an aqueous pigment dispersion including a pigment, an anionic group-containing organic polymer compound, and bio-nanofibers having an average diameter of 1 nm or more and 100 nm or less and an aspect ratio of 100 or more, and also provides an aqueous ink using the aqueous pigment dispersion. The bio-nanofibers are preferably cellulose nanofibers or chitosan nanofibers. The anionic group-containing organic polymer compound is preferably at least one selected from the group consisting of acrylic resins having anionic groups, polyurethane resins having anionic groups, and polysaccharide derivatives having anionic groups.

Aqueous pigment dispersion and aqueous ink

The present invention provides an aqueous pigment dispersion including at least a pigment, colloidal silica, bio-nanofibers having an average diameter of 1 nm to 100 nm and an aspect ratio of 100 or more, an anionic group-containing organic polymer compound, and also provides an aqueous ink. The bio-nanofibers are preferably cellulose nanofibers or chitosan nanofibers, and the ratio between the pigment, the colloidal silica, and the bio-nanofibers preferably satisfies (1) colloidal silica/pigment=1/100 to 20/100 or (2) colloidal silica/bio-nanofibers=1/2 to 10/1 and (3) bio-nanofibers/pigment=1/100 to 15/100.

Disclosed are an ink jet recording water-based ink having excellent long-term storage stability and ejection stability at a pigment concentration greater than or equal to a certain level and a simple and efficient method for producing such a water-based ink. The present invention provides an ink jet recording water-based ink in which the total content of polyvalent metals as impurities in the water-based ink is not more than 1.2 ppm in terms of 1 mass % of a pigment concentration. Furthermore, the present invention provides a method for producing an ink jet recording water-based ink; the method enables efficient production of the above-mentioned ink jet recording water-based ink through a contact treatment with a particulate chelating resin in which each resin particle contains both an alkali metal-bonded chelating group and a hydrogen-bonded chelating group.

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Kita-adachi-gun, Japan

Yukihiko Kawaharada