Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: It is an object of the present invention to provide an aqueous ink composition for inkjet recording, the aqueous ink composition having satisfactory dispersion properties and ejection properties, excellent scratch resistance and rub resistance, and high color developability and gloss. To this end, the present invention provides an aqueous ink composition for inkjet recording, the aqueous ink composition containing a pigment (a), an anionic group-containing resin (b), a humectant (c), a basic compound (d), a water-dispersible polyurethane resin (e), and a polyolefin wax (f). The water-dispersible polyurethane resin content is preferably in the range of 0.2% to 5% by mass. The value of (Cf·Df) is preferably in the range of 3 to 100, wherein Cf represents the polyolefin wax (f) content (percent by mass), and Df represents the volume-average particle size (nm).

Abstract: 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.