Pigment dispersion solution and manufacturing method thereof

A method for producing a pigment dispersion to be used for preparing an aqueous inkjet ink, the pigment dispersion comprising:

• a pigment;
• a dispersant;
• a water-soluble organic solvent;
• and water, the method comprising:
• dispersing a mixture comprising:
• biomass-derived raw material carbon black having a number average particle size of primary particles of 20 to 400 nm;
• the dispersant;
• the water-soluble organic solvent;
• and water,
• wherein the pigment is biomass-derived carbon black having a number average particle size of 80 to 300 nm in a state of being dispersed in the pigment dispersion,
• the dispersant is a polymer at least part of carboxy groups of which are neutralized with an alkali, the polymer comprising:
• a constituent unit (i) derived from at least any one of (meth)acrylic acid, itaconic acid, and an itaconic acid monoester;
• and a constituent unit (ii) derived from a biomass-derived (meth)acrylate,
• the polymer has an acid value of 50 to 150 mgKOH/g, a number average molecular weight of 5,000 to 20,000, and a polydispersity index (weight average molecular weight/number average molecular weight) of 2.5 or less,
• the content of the constituent unit (ii) in the polymer is 50% by mass or more,
• the biomass-derived (meth)acrylate comprises:
• isobornyl methacrylate;
• and at least one selected from the group consisting of ethyl methacrylate, tetrahydrofurfuryl methacrylate, dodecyl methacrylate, and octadecyl methacrylate, and
• the proportion of isobornyl methacrylate in all the biomass-derived (meth)acrylates is 40% by mass or more.