Ricoh Company, Ltd.

Nobuyuki Sakamoto

Kazukiyo Nagai

Akihiko Matsuyama

Mitsuru Naruse

Yuusuke Koizuka

Minoru Hakiri

Keita Katoh

Masayasu Nonogaki

Yosuke Matsuoka

Masatomo Takahashi

An inkjet recording ink, including: water; a water-soluble solvent; a pigment; and a phosphate group-containing copolymer, wherein the phosphate group-containing copolymer includes a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2): wherein, in the general formula (1), Rrepresents either of a hydrogen atom and a methyl group; and Mrepresents any of an alkali metal ion, an organic amine ion and a hydrogen ion, one-half or more of the Min the copolymer is an alkali metal ion or an organic amine, and the remainder is a hydrogen ion; wherein, in the general formula (2), Rrepresents either of a hydrogen atom and a methyl group.

Inkjet recording ink and ink cartridge using the ink, inkjet recording apparatus, inkjet recording method and ink recording matter

An inkjet recording ink, including: water; a water-soluble solvent; a pigment; and a phosphate group-containing copolymer, wherein the phosphate group-containing copolymer includes a structural unit represented by the following general formula (1) and a structural unit represented by the following structural formula (1): wherein, in the general formula (1), Rrepresents either of a hydrogen atom and a methyl group; and Mrepresents any of an alkali metal ion, an organic ammonium ion, an organic amine ion and a hydrogen ion, one-half or more of the Min the copolymer is an alkali metal ion, an organic ammonium ion or an organic amine, and the remainder is a hydrogen ion: 

Inkjet recording ink and ink cartridge using the ink, inkjet recording apparatus, inkjet recording method and ink recorded matter

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Ibaraki, Japan

Nobuyuki Sakamoto