Riso Kagaku Corporation

Kazuyuki Ando

Shinichiro Shimura

Marie Morinaga

Hikaru Sugiura

Shinsuke Ozawa

Yoshifumi Watanabe

Manami Shimizu

Naofumi Ezaki

Toshihiro Endo

Noriaki Sugawara

Hiroshi Hayashi

Tetsuo Hosoya

Teruaki Okawa

Kyoko Tsumura

Provided is an oil-based inkjet ink containing a pigment and a fatty acid ester-based solvent represented by general formula (1) shown below and having at least 18 but not more than 29 carbon atoms per molecule. In general formula (1), Rrepresents an alkyl group of 5 or more carbon atoms, Rrepresents an alkyl group of 6 or more carbon atoms, and at least one of Rand Ris a branched alkyl group of 9 or more carbon atoms having a side chain of 4 or more carbon atoms. 

Oil-based inkjet ink

An oil-based inkjet ink can be provided that prevents adhesion of the ink to the nozzle plate, thereby preventing ink misfires and discharge defects from the inkjet nozzles. The oil-based inkjet ink contains a pigment, a non-aqueous solvent, and a compound represented by general formula (1) shown below. (In general formula (1), m represents 1 or 2, each of Rand Rindependently represents a monovalent saturated hydrocarbon group, Rrepresents a single bond or a divalent saturated hydrocarbon group, and Rrepresents a monovalent or divalent saturated hydrocarbon group.)

An ink is provided which can prevent the deformation and degradation of resin products by printed items, and is also suitable for inkjet printing. The oil-based inkjet ink contains a colorant and a fatty acid ester-based solvent represented by general formula (1) shown below and having 12 to 23 carbon atoms in one molecule. (In general formula (1), each of Rand Rindependently represents an alkyl group, and at least one of the alkyl groups of Rand Ris a branched alkyl group having a side chain of at least 4 carbon atoms.).

An oil-based inkjet ink can be provided which prevents dye conversion of a dye lake pigment contained in the ink, prevents adhesion of the ink to the nozzle plate, and yields excellent drying properties for printed items. The oil-based inkjet ink contains a dye lake pigment, a pigment dispersant and a non-aqueous solvent, wherein the non-aqueous solvent contains a silicone oil having a surface tension of at least 20 mN/m but not more than 28 mN/m. The surface tension of the silicone oil is preferably at least 22 mN/m but not more than 26 mN/m.

An oil-based inkjet ink set is disclosed that includes: an oil-based inkjet ink A containing a non-aqueous solvent, the non-aqueous solvent of the oil-based inkjet ink A containing at least 15% by mass of a silicone oil relative to the total mass of the non-aqueous solvent of the oil-based inkjet ink A, and an oil-based inkjet ink B containing a non-aqueous solvent, the non-aqueous solvent of the oil-based inkjet ink B containing at least 50% by mass of a petroleum-based hydrocarbon solvent relative to the total mass of the non-aqueous solvent of the oil-based inkjet ink B. A method for producing a printed item is also disclosed.

Oil-based inkjet ink set and method for producing printed item

An oil-based inkjet ink is disclosed, the oil-based inkjet ink containing a pigment, a pigment dispersant and a non-aqueous solvent, wherein the pigment contains an acidic carbon black having a pH of 2 to 6, the non-aqueous solvent contains a modified silicone oil having a surface tension of not more than 27 mN/m, and an amount of the modified silicone oil, relative to a total mass of the oil-based inkjet ink, is at least 15% by mass but not more than 80% by mass.

An oil-based inkjet ink can be provided which exhibits excellent discharge stability even after a long idle period, and also yields high image density and prevents show-through in printed items. The oil-based inkjet ink contains a pigment, an amide-based dispersant and a non-aqueous solvent, wherein the non-aqueous solvent contains a modified silicone oil having 2 or 3 silicon atoms in one molecule, and a petroleum-based hydrocarbon solvent.

A method for producing a printed item including discharging two or more inks by an inkjet method toward a recording medium to form an image is disclosed, wherein the two or more inks include a first oil-based inkjet ink containing a first colorant and a non-aqueous solvent and having an ink surface tension of less than 27.0 mN/m, and a second oil-based inkjet ink containing a second colorant and a non-aqueous solvent and having an ink surface tension of 27.0 mN/m or greater, and the method includes discharging the first oil-based inkjet ink toward the recording medium at a discharge volume of at least 20 pl per one liquid droplet to form dots with the first oil-based inkjet ink, and subsequently discharging the second oil-based inkjet ink toward the recording medium at a discharge volume of less than 20 pl per one liquid droplet so as to overlap with the dots formed with the first oil-based inkjet ink.

Method for producing printed item

Disclosed is an oil-based inkjet ink containing a colorant and a non-aqueous solvent, wherein the non-aqueous solvent contains at least 15% by mass but not more than 100% by mass, relative to the total mass of the non-aqueous solvent, of an organosilicon compound having 2 to 6 silicon atoms in one molecule, having an organic group in which a carbon atom is bonded directly to a silicon atom and in which the total number of carbon atoms and oxygen atoms is at least 4, and having a total number of carbon atoms and oxygen atoms, contained within all of the organic groups in which the total number of carbon atoms and oxygen atoms is at least 4, that is from 4 to 20 within one molecule.

An oil-based inkjet is disclosed, the oil-based inkjet ink containing a pigment, a pigment dispersant and a non-aqueous solvent, wherein the non-aqueous solvent contains a silicone oil having a surface tension of at least 19.0 mN/m but less than 24.0 mN/m and a polar solvent having a surface tension of at least 27.0 mN/m, and a surface tension of the ink is at least 23.0 mN/m but less than 27.0 mN/m.

An inkjet printer includes: an oil-based ink containing silicone oil; and inkjet heads each including a nozzle row in which nozzles configured to eject the oil-based ink to a print medium conveyed in a conveyance direction are arranged, the inkjet heads being arranged adjacent to each other with the nozzles in each nozzle row arranged in a direction non-orthogonally intersecting the conveyance direction.

Inkjet printer using oil-based ink

A colored resin particle dispersion and an ink are provided which yield excellent abrasion resistance for printed items. Moreover, a colored resin particle dispersion and an inkjet ink are provided which exhibit excellent abrasion resistance, water resistance and marker resistance, as well as favorable storage stability. Specifically provided are a colored resin particle dispersion containing colored resin particles, a basic dispersant, and a non-aqueous solvent, wherein the colored resin particles include a colorant and a crosslinked solid resin, and an inkjet ink containing this colored resin particle dispersion.

Colored resin particle dispersion and inkjet ink

A colored resin particle dispersion and an ink are provided which exhibit excellent color development and abrasion resistance. Moreover, a colored resin particle dispersion and an inkjet ink are provided which exhibit excellent color development and abrasion resistance, together with excellent water resistance and marker resistance. Specifically provided are a colored resin particle dispersion containing colored resin particles, a basic dispersant, and a non-aqueous solvent, wherein the colored resin particles contain a colorant, and a phosphorylated solid resin and/or a nitrated solid resin. The phosphorylated solid resin may include a phosphorylated polyvinyl alcohol and/or a phosphorylated polyvinyl acetal, and the nitrated solid resin may include a nitrocellulose.

A colored resin particle dispersion and an ink are provided which yield excellent abrasion resistance and prevent change in the color tone. Moreover, a colored resin particle dispersion and an inkjet ink are provided which exhibit excellent abrasion resistance, together with excellent water resistance and marker resistance. Specifically provided is a colored resin particle dispersion containing colored resin particles, a basic dispersant, and a non-aqueous solvent, wherein the colored resin particles include a colorant, a solid resin and a liquid organic compound having an acidic group, and the oxidation-reduction potential of the colored resin particle dispersion is 300 mV or less. Also provided is an inkjet ink containing this colored resin particle dispersion.

A colored resin particle dispersion and an ink are provided which exhibit excellent abrasion resistance of the printed items and excellent storage stability of the dispersion. Specifically provided is a colored resin particle dispersion comprising colored resin particles containing a colorant and a solid resin, a basic dispersant, and a non-aqueous solvent, wherein the solid resin is a resin having alkoxy groups and/or a polysilsesquioxane. The resin having alkoxy groups preferably has methoxy groups and/or ethoxy groups. Further, the resin having alkoxy groups preferably contains at least one of a polyamide resin having methoxymethyl groups, a methoxypolysilsesquioxane and an ethoxypolysilsesquioxane.

Growing community of inventors

Ibaraki, Japan

Kazuyuki Ando