Pigment dispersion and method for producing resin-treated pigment in the pigment dispersion

A pigment dispersion for use as a colorant for an oil-based product, the pigment dispersion comprising:

• a dispersion medium, which comprises at least one medium selected from the group consisting of monomers, organic solvents, thermoplastic resins, thermosetting resins, and UV/ER-curable resins;
• and
• a resin-treated pigment dispersed in the dispersion medium,
• wherein a resin-treated pigment comprises:
• a pigment;
• and
• a polymer of an unsaturated bond-containing monomer,
• wherein the polymer is an acrylic A-B block copolymer, which is formed of a polymer block A, which is formed of an A chain, and a polymer block B formed of a B chain that comprises an addition-polymerizable monomer having a UV-absorbing group in an amount from 5 to 70 mass % relative to a total amount of monomers constituting the polymer,
• wherein the UV-absorbing group is a UV-absorbing benzotriazole group, a UV-absorbing triazine group, or a UV-absorbing benzophenone group,
• the acrylic A-B block copolymer contains in its structure, a plenty of aromatic rings provided by the UV-absorbing group, and the aromatic rings are concentrated in the B chain of the acrylic A-B block copolymer,
• the polymer block A formed of the A chain in the A-B block copolymer is an acrylic polymer that is miscible with the dispersion medium, and
• the polymer block B formed of the B chain in the A-B block copolymer is an acrylic polymer comprising the addition-polymerizable monomer having the UV-absorbing group, and the polymer block B includes 70 mass % or more of a total mass of the addition-polymerizable monomer included in the A-B block copolymer, and
• a weight ratio of the pigment to the polymer (pigment:polymer) is from 50 to 95 of the pigment to from 50 to 5 of the polymer, wherein the pigment is encapsulated with the acrylic A-B block copolymer.