Dic Corporation

Atsuo Kobayashi

Satoshi Idemura

Shinichi Okada

Masahiro Kido

Soetrisno Misawa

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.

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

A pigment dispersion of the present invention includes a bisacetoacetarylide pigment (a); a styrene-acrylic acid-based copolymer (b); a basic compound (c); and a wetting agent (d), wherein the wetting agent (d) includes at least one diol compound (e), the diol compound (e) is selected from the group consisting of dipropylene glycol, 2-ethyl-1,3-hexanediol, and 1,2-hexanediol the mass ratio (e)/(a) of the diol compound (e) and the bisacetoacetarylide pigment (a) is within a range from 3/100 to 8/100.

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Niiza, Japan

Atsuo Kobayashi