Dic Corporation

Masahiro Kido

Shinichi Okada

Kumiko Iizasa

Atsuo Kobayashi

Soetrisno Misawa

A method for producing an aqueous pigment dispersion liquid, including: a kneading step of kneading a mixture of a quinacridone pigment (a), a pigment derivative (b), an organic high-molecular compound having an anionic group (c), a basic compound (d), and an acetylene glycol surfactant (e) in a closed kneader to prepare a pigment-kneaded material having a solid content in the range of 50% to 80% by mass; and a step of diluting the pigment-kneaded material with an aqueous medium. A method for producing a water-based ink for ink jet recording, including a step of diluting the aqueous pigment dispersion liquid with an aqueous medium.

Methods for producing aqueous pigment dispersion liquid and water-based ink for ink jet recording

A highly efficient method is provided for producing a water-based ink for ink jet recording with which the number of coarse particles in a water-based pigment dispersion liquid is significantly reduced, dispersed particles are made finer, the dispersion stability is improved, the storage stability is improved, and high discharge stability is achieved when a water-based ink for ink jet recording is produced. Particularly, provided is a method for producing a water-based pigment dispersion liquid, the method including kneading a mixture containing a quinacridone type pigment (a), a styrene-acrylic acid type copolymer (c), a basic compound (d), and a polyoxyalkylene glycol or its derivative (e) to prepare a pigment dispersion that is solid at room temperature and mixing a aqueous medium and the pigment dispersion to decrease the viscosity and liquefy the pigment dispersion.

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Kita-adachi-gun, Japan

Masahiro Kido