Kao Corporation

Nobushige Tanaka

Takehiro Tsutsumi

Koji Azuma

Takashi Oda

Ryuma Mizushima

Isao Tsuru

Makoto Torizuka

Hirohisa Suzuki

Katsuhiko Rindo

Nobuyuki Takizawa

Masato Hoshi

Makoto Sakakibara

Kenji Kaida

Akira Umada

Kana Fujiwara

The present invention relates to crosslinked core/shell polymer particles containing a pigment which are usable in a water-based ink for ink-jet printing and exhibit excellent optical density and gloss and are prevented from suffering from occurrence of bronzing, wherein the polymer particles each include a core portion and a shell portion which are respectively made of a crosslinked polymer, and a weight ratio of the pigment to the pigment-containing crosslinked core/shell polymer particles [(weight of the pigment/weight of the pigment-containing crosslinked core/shell polymer particles)&#xd7;100] is from 25 to 75. The present invention further relates to a water dispersion and a water-based ink for ink-jet printing which contain the crosslinked core/shell polymer particles and a process for producing crosslinked polymer particles.

Crosslinked core/shell polymer particles

There are provided a water dispersion for ink-jet printing which contains a water dispersion of particles of a vinyl polymer or a polyester-based polymer which contain a colorant (B), and a water-insoluble organic compound (A) except for aliphatic acid derivatives; a water-based ink containing the water dispersion; a print obtainable by printing images or characters with the water-based ink; and a process for producing the water dispersion. Also, there are provided an ink set for ink-jet printing containing two or more kinds of inks having different colors from each other wherein the inks each contain a water dispersion of particles of a vinyl polymer or a polyester-based polymer which contain a colorant (B), and a water-insoluble organic compound (A) except for aliphatic acid derivatives; and a process for producing a print using the ink set. The water-based ink can provide multi-order color images or composite black images which exhibits a high optical density and is excellent in gloss and image clarity.

Water-based inks for ink-jet printing

A water dispersion for inkjet printing which contains polymer particles containing a colorant. The polymer constituting the polymer particles is produced by the copolymerization of a monomer mixture in the presence of a-methylstyrene dimer. The water dispersion for inkjet printing and a water-based ink for inkjet printing containing the water dispersion exhibit excellent jetting properties and a high optical density.

Water-based ink for inkjet printing

Provided are a water dispersion for ink-jet printing, wherein it is a water dispersion of water-insoluble graft polymer particles containing a colorant; the above graft polymer contains a principal chain having a constitutional unit derived from a vinyl base monomer and a side chain which is derived from a macromer containing an aromatic ring and having a polymerizable functional group at one end; both of the Log P values of the above principal chain and the above side chain are positive; and a difference between both falls in a specific range, and a water-based ink containing the same. The above water-based ink is excellent in a discharge stability, a storage stability, a heat stability and a water resistance.

Water dispersion for ink-jet printing

An aqueous dispersion for inkjet recording containing colorant-containing water-insoluble vinyl polymer particles dispersed in water, wherein the water-insoluble vinyl polymer contains a constitutive unit derived from a styrenic macromer (a) which has a polymerizable functional group at one end, wherein the styrenic macromer (a) has a number-average molecular weight of from 1000 to 5000 and a molecular weight distribution (weight-average molecular weight/number-average molecular weight) of from 1.0 to 2.5; and a water-based ink for inkjet recording containing the aqueous dispersion. The aqueous dispersion is capable of realizing a water-based ink for inkjet recording, which has excellent storage stability, a high optical density, and gives a high gloss.

Aqueous dispersion for inkjet recording

A water-based ink containing an aqueous dispersion of water-insoluble vinyl polymer particles containing a pigment, wherein the water-insoluble vinyl polymer is prepared by copolymerizing a monomer mixture containing (a) a monomer having a salt-forming group, (b) a monomer having a long-chain alkyl group, (c) a macromer, (d) a monomer having a polyoxyalkylene group, and (e) a monomer copolymerizable with the monomer having a salt-forming group (a), the monomer having a long-chain alkyl group (b), the macromer (c) and the monomer having a polyoxyalkylene group (d). The water-based ink can be suitably used, for instance, as a water-based ink for inkjet recording and the like.

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Wakayama, Japan

Nobushige Tanaka