Dic Corporation

Kenji Sugo

Satoshi Idemura

Hiroshi Katsube

Masanori Fujimaki

Tomoyuki Uezono

Shoichi Hotate

Hideki Ganbayashi

Wakana Naito

Hiroshi Maru

It is an object of the present invention to provide an aqueous pigment dispersion that can be used to produce an ink with high ejection stability and long-term storage stability and has high dispersibility with a lower likelihood of causing aggregation or precipitation of pigments. The present invention relates to an aqueous pigment dispersion containing a pigment dispersing resin (A), a pigment (B), an organic solvent (C), and an aqueous medium (D), wherein the pigment dispersing resin (A), the pigment (B), and the organic solvent (C) have specified Hansen solubility parameters.

Aqueous pigment dispersion and method for producing the same

The present invention relates to an ink-jet recording ink which can simultaneously achieve long-term preservation stability, high luster, and light fastness of a printed image, and an aqueous pigment liquid dispersion to produce the ink. Moreover, the present invention relates to a production method of the aqueous pigment liquid dispersion. For the aforementioned objects, the applicant provides an aqueous pigment liquid dispersion, including: C. I. pigment green 36 (a); a styrene-acrylic acid type copolymer (b); a basic compound (c); and a wetting agent (d), wherein the styrene-acrylic acid type copolymer (b) has styrene-based monomer units of 60 mass % or more in the total of all the monomer units, an acid value of 120 to 240, and a weight average molecular weight of 6,000 to 40,000, and the mass ratio (b)/(a) is within a range from 0.15 to 0.25.

Aqueous pigment liquid dispersion and ink-jet recording ink, and production method of aqueous pigment liquid dispersion

A production method of an aqueous pigment dispersion liquid of the present invention includes: a kneading step of kneading a mixture including (a) C. I. pigment violet 23, (b) a styrene-acrylic acid-based copolymer with an acid value of 50 to 300 mgKOH/g, (c) an alkali metal hydroxide, (d) water, and (e) a wetting agent, thereby producing a colored, kneaded material; and a dispersion step of dispersing the pigmented, kneaded material in an aqueous medium by using a dispersing machine with media, wherein the mass ratio of (b)/(a) in the kneading step is within a range of 0.15 to 0.45, the mass ratio of (d)/(a) in the first half of the kneading step is within a range of 0.04 to 0.42, and the change in viscosity of materials to be dispersed in the dispersion step is 10% or lower.

Aqueous pigment dispersion liquid and ink-jet recording ink

A yellow water-based pigment dispersion liquid is provided that includes pigment particles dispersed with a significantly small particle size, that has excellent dispersion stability, that causes less precipitation even at low viscosity, and that provides high gloss when the dispersion liquid is used as a main component of inkjet recording ink. In order to produce the water-based pigment dispersion liquid, it is important to add, as a kneading aid, an acetylene glycol surfactant having a specific structure and an HLB value of 8 to 12 to a mixture containing a bis-acetoacetallylide pigment, a styrene-acrylic acid copolymer having an acid value of 145 to 175, a basic compound, and a humectant and then to knead the resultant mixture to obtain a pigment dispersion. By dispersing the pigment dispersion in a water-based medium, a water-based pigment dispersion liquid for inkjet recording having the characteristics above can be produced.

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Kita-adachi-gun, Japan

Kenji Sugo