Abstract: An object of the present invention is to provide a method for producing a pigment composition that can achieve both a reduction in the number of coarse particles that may be contained in the pigment composition and improvement in the production efficiency of the pigment composition. The present invention relates to a method for producing a pigment composition in which a pigment is dispersed in a liquid medium by a pigment dispersion resin by undergoing step 1 in which a raw material composition containing the pigment, the pigment dispersion resin, and the liquid medium is processed with a dispersing machine, the dispersing machine being a dispersing machine including a configuration allowing the raw material compositions to collide with each other.

Abstract: An object of the present invention is to provide a method for producing a pigment composition that can efficiently reduce the number of coarse particles in a pigment composition such as an aqueous pigment dispersion. The inventors of the present invention have achieved this object by a method of producing a pigment composition for ink, including a processing step of crushing or cracking a pigment component in a raw material composition containing the pigment component and a liquid medium using a rotor-stator processing machine 100.

Abstract: The problem to be solved by the present invention is to provide a method for producing an aqueous pigment dispersion that has certain dispersion stability with which the formation of coarse particles with time and the settling of a pigment and the like with time can be reduced and that can be used for producing an ink having excellent discharge stability. The present invention relates to a method for producing an aqueous pigment dispersion, the method including kneading a composition including a pigment including one or more materials selected from the group consisting of a violet pigment, a green pigment, and an orange pigment and a resin, the composition having a nonvolatile content of 50% by mass or more, under predetermined conditions and subsequently performing a centrifugation treatment.

Abstract: The method for producing a pigment-kneaded product includes a step [1] of supplying at least a pigment and a resin to a container provided in a kneading apparatus and a step [2] of kneading the resulting content (content (a1)) present in the container until a storage elastic modulus of content (a1) at an angular frequency of 1 rad/s, which is obtained by measurement of dynamic viscoelasticity at 25° C., reaches a range of 200 kPa to 30,000 kPa.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.