Kao Corporation

Koji Azuma

Takehiro Tsutsumi

Nobushige Tanaka

Ryuma Mizushima

Isao Tsuru

Yusuke Shimizu

Hirotaka Takeno

Michitaka Sawada

Tetsuya Eguchi

Hirokazu Hyakuda

Hiroki Kawaguchi

Kuniyasu Kawabe

Tadashi Sakuma

Yuki Wakabayashi

Tetsuya Ueno

Shigemi Wakabayashi

Kazunari Takemura

Shigeki Nagashima

Nobuyuki Takizawa

Toshiya Iwasaki

Masato Hoshi

Kenji Kaida

Akira Umada

Tekehiro Tsutsumi

The present invention relates to a water-based pigment dispersion containing a polymer dispersant and a pigment, the polymer dispersant being prepared by crosslinking a carboxy group-containing water-insoluble polymer (A) with a water-insoluble polyfunctional epoxy compound, in which carboxy groups of the water-insoluble polymer (A) are at least partially neutralized by an alkali metal compound, and the water-based pigment dispersion satisfies the following conditions 1 to 3. The water-based pigment dispersion of the present invention can exhibit excellent redispersibility capable of suppressing solidification of the pigment or the polymer in ink ejection nozzles and can ensure good storage stability under high-temperature conditions. The conditions 1 to 3 are as follows: Condition 1: a value calculated according to the formula: {[100&#x2212;(neutralization degree)&#x2212;(crosslinking degree)]/100}&#xd7;[acid value of water-insoluble polymer (A)] is from &#x2212;30 to 30 mgKOH/g: Condition 2: a value calculated according to the formula: [(neutralization degree)/100]&#xd7;[acid value of water-insoluble polymer (A)] is from 80 to 180 mgKOH/g; and Condition 3: a value calculated according to the formula: [(crosslinking degree)/100]&#xd7;[acid value of water-insoluble polymer (A)] is from 80 to 180 mgKOH/g.

Aqueous pigment dispersion

The present invention relates to a water-based pigment dispersion having not only excellent storage stability capable of suppressing solidification of a pigment or the like in ink ejection nozzles, but also excellent ejection properties and fixing properties, while maintaining good water resistance of the pigment dispersion as an advantage attained by using the pigment therein. That is, the present invention relates to a water-based pigment dispersion including a pigment, a polymer dispersant and an aqueous medium in which the pigment is dispersed in the aqueous medium using the polymer dispersant, the polymer dispersant being a water-insoluble polymer including carboxy groups that are at least partially neutralized with an alkali metal hydroxide, and having a crosslinked structure obtained by reacting a part of the carboxy groups with a water-insoluble polyfunctional epoxy compound, said water-based pigment dispersion satisfying the following conditions 1 and 2: Condition 1: a value calculated according to the formula: {[100&#x2212;(neutralization degree)&#x2212;(crosslinking degree)]/100}&#xd7;(acid value of carboxy group-containing water-insoluble polymer) being from 32 to 130 mgKOH/g; and Condition 2: a value calculated according to the formula: [(neutralization degree)/100]&#xd7;(acid value of carboxy group-containing water-insoluble polymer) being from 48 to 144 mgKOH/g.

Water-based pigment dispersion

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

The present invention relates to a water dispersion for ink-jet printing including two kinds of carbon blacks (a) and (b) and a water-insoluble polymer which adheres to a surface of the respective carbon blacks (a) and (b), wherein the carbon black (a) has an acid group content of from 0 to 200 &#x3bc;mol/g and the carbon black (b) has an acid group content of more than 200 &#x3bc;mol/g but not more than 1000 &#x3bc;mol/g, and a difference between acid group contents of the carbon blacks (a) and (b) is from 100 to 1000 &#x3bc;mol/g, and a water-based ink for ink-jet printing which contains the water dispersion. The water-based ink is excellent in image density, fixing property, high lighter fastness, image uniformity, ejection reliability and storage stability.

Water-based ink for ink-jet recording

The present invention relates to (A) a water dispersion for ink-jet printing including particles of a waster-insoluble crosslinked polymer which contain a colorant, and a water-insoluble organic compound, wherein the water-insoluble crosslinked polymer is (1) a polymer produced by crosslinking a water-insoluble polymer with a crosslinking agent; (2) a polymer produced by crosslinking 100 parts by weight of the water-insoluble polymer with 0.5 to 9.5 parts by weight of the crosslinking agent; or (3) a polymer having a weight-average segment molecular weight of from 1,400 to 20,000 as calculated from [(weigh-average molecular weight of the water-insoluble polymer)/(number of molar equivalents of the crosslinking agent to be reacted with 1 mol of the water-insoluble polymer+1)]; (B) an ink for ink-jet printing containing the above water dispersion which is excellent in gloss and storage stability; and (C) particles of the water-insoluble crosslinked polymer.

Water-based inks for ink-jet printing

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.

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

The present invention relates to a water dispersion for ink jet recording, comprising water-insoluble vinyl polymer particles containing a colorant, wherein the water-insoluble vinyl polymer is a water-insoluble vinyl polymer obtained by polymerizing a monomer mixture comprising: wherein Rrepresents a hydrogen atom or a methyl group, Rrepresents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or a phenyl group whose hydrogen atom may be substituted with an alkyl group having 1 to 9 carbon atoms and m denotes a number from 65 to 100;

Water dispersion for ink jet recording

The invention provides a process for producing a water dispersion for ink jet recording,which comprises the following steps 1 and 2:

Aqueous ink for ink jet recording

A water-based ink comprising an aqueous dispersion of polymer particles made of a water-insoluble vinyl polymer containing a colorant, wherein the water-insoluble vinyl polymer is prepared by polymerizing a monomer composition comprising a specific monomer A such as a monomer A1 represented by the formula (I): wherein Ris hydrogen or methyl, Ris hydrogen, alkyl or alkylphenyl, and n is 1 to 30; a monomer having a salt-forming group; and a monomer copolymerizable with the monomer A and the monomer having a salt-forming group. The water-based ink can be suitably used as a water-based ink for inkjet recording and the like.

Water-based ink

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

Aqueous ink for ink-jet printing comprises an emulsion of fine polymer particles and contains at least one compound selected from an amino acid or a salt thereof and the like.

Aqueous ink for ink-jet printing

A process for producing an aqueous ink for inkjet printing capable of giving an elevated print density of printed matters, being improved in fixability to the material to be printed, water resistance and improved storage stability and scarcely scorching onto a printer head. This process comprises dissolving a salt-forming group-having polymer and a hydrophobic dye in a water-insoluble organic solvent to obtain a solution, adding water and a neutralizing agent optionally together with a surfactant to the solution to ionize the salt-forming group of the polymer, emulsifying the resulting mixture, and removing out the solvent from the emulsion to obtain an ink containing an aqueous dispersion of the polymer particles in which the dye has been encompassed.

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Wakayama, Japan

Koji Azuma