Aqueous pigment dispersion liquid and aqueous pigment inkjet ink using same

摘要

The present invention is an aqueous pigment dispersion liquid for inkjet comprising a pigment and a pigment dispersant. The pigment dispersant is at least any one of a graft copolymer and a block copolymer each comprising a polymer chain A and a polymer chain B, wherein the polymer chain A comprises 20 to 60 mass % of a constituent unit derived from a first cycloalkyl group-containing (meth)acrylate, 10 to 35 mass % of a constituent unit derived from (meth)acrylic acid, and 5 to 70 mass % of a constituent unit derived from another (meth)acrylate and the polymer chain B comprises at least any one of a constituent unit derived from a second cycloalkyl group-containing (meth)acrylate and a constituent unit derived from a vinyl monomer or (meth)acrylate having an aromatic ring.

主权项

1. An aqueous pigment dispersion liquid for inkjet comprising:
a pigment in a range from 5 to 35 mass %; a pigment dispersant in a range from 0.5 to 25 mass %; an aqueous organic solvent, which is an organic solvent having miscibility with water, in a range from 5 to 30 mass %; and water in a range from 20 to 80 mass %, wherein the pigment dispersant comprises a graft copolymer in which a polymer chain A is grafted onto a polymer chain B, the polymer chain A comprises:
a constituent unit derived from a first cycloalkyl group-containing (meth)acrylate in a range from 20 to 60 mass %;a constituent unit derived from (meth)acrylic acid in a range from 10 to 35 mass %; anda constituent unit derived from another (meth)acrylate in a range from 5 to 70 mass %, and the polymer chain A has a number average molecular weight in a range from 1,000 to 10,000, the polymer chain B comprises at least one material selected from the group consisting of a constituent unit derived from a second cycloalkyl group-containing (meth)acrylate, a constituent unit derived from a vinyl monomer having an aromatic ring, and a constituent unit derived from (meth)acrylate having an aromatic ring,
wherein the second cycloalkyl group-containing (meth)acrylate for the polymer chain B is selected from the group consisting of cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclohexyloxyethyl (meth)acrylate, and tricyclodecyl (meth)acrylate, isobornyl (meth)acrylate,the vinyl monomer having an aromatic ring for the polymer chain B is selected from the group consisting of styrene, vinyl toluene, and vinyl naphthalene, andthe (meth)acrylate having an aromatic ring for the polymer chain B is selected from the group consisting of phenyl (meth)acrylate, naphthoxy (meth)acrylate, benzyl (meth)acrylate, phenoxy ethyl (meth)acrylate, and para-cumyl phenol ethylene oxide-modified (meth)acrylate, a mass ratio A:B of the polymer chain A to the polymer chain B is in a range of 30 to 70:70 to 30, and the graft copolymer has a number average molecular weight in a range from 2,000 to 20,000.