An ink set has two or more aqueous pigment-based inks, each of which has 75-95 weight %, a) one or more pigment colorants, and b) one or more water-miscible humectants that are present in a total amount of at least 1 weight % and up to and including 20 weight %, and consist essentially of compounds, each of which has a carbon atom to oxygen atom ratio of at least 1.0:1.0 and only two hydroxy groups. The weight % amounts of water and the b) water-miscible humectants are based on the total weight of each aqueous pigment-based ink. The aqueous pigment-based inks in the ink set can be used individual or in combination to provide monochrome or polychrome inkjet-printed images on various ink-receptive media and using various inkjet printing equipment and methods.

The present invention relates to an ink-jet printing method of overprinting a first ink and a second ink on a low-liquid absorbing printing medium, in which the first ink and the second ink are respectively in the form of a water-based ink containing a colorant (A), a polymer (B), an organic solvent (C) and water, and satisfy the following formulae (1) and (2), said ink-jet printing method including the steps of forming characters or images using at least one ink as the first ink, and then forming a background image using the second ink such that the background image is superimposed on at least a part of the characters or images formed by the first ink: [T.sub.2−T.sub.1]<0 mN/m (1); and [V.sub.2−V.sub.1]≥1.0 mPa.Math.s (2) wherein T.sub.2 is the static surface tension of the second ink; T.sub.1 is the static surface tension of the first ink; V.sub.2 is the viscosity of the second ink as measured at 32° C.; and V.sub.1 is the viscosity of the first ink as measured at 32° C. According to the method of the present invention, it is possible to obtain good printed characters or images that are excellent in uniformity of solid image printing and suffer from less intercolor bleeding.

An ink set including an inkjet ink, and a treatment liquid used in combination with the inkjet ink, wherein the inkjet ink includes a pigment, a water-soluble organic solvent, a surfactant and water, the treatment liquid includes a coagulant, an organic solvent and water, the coagulant includes calcium nitrate in an amount of 21.5 to 41.7% by mass relative to the total mass of the treatment liquid, an amount of organic solvent having a boiling point at one atmosphere of 240° C. or higher in the treatment liquid is not more than 8% by mass, a pH of the treatment liquid is within a range from 3.5 to 10.5, and a viscosity of the treatment liquid at 25° C. is within a range from 5.5 to 18.5 mPa.Math.s.

A printing apparatus includes an ejection head including a first nozzle row configured to eject, toward a recording medium, a first liquid containing a photopolymerization initiator and a second nozzle row configured to eject, toward the recording medium, a second liquid containing the polymerizable compound and a color material and not containing the photopolymerization initiator, a driving unit configured to change relative positions of the ejection head and the recording medium, and an irradiation unit configured to irradiate, with the light, the recording medium onto which the first liquid and the second liquid are deposited. The first liquid and the second liquid are ejected from the ejection head so that the second liquid overlaps the first liquid on a surface of the recording medium. A distance between the irradiation unit and the first nozzle row is longer than a distance between the irradiation unit and the second nozzle row.

Dot data for a boundary zone between metallic ink and color ink is changed to increase a time difference between a scan for applying the metallic ink and a scan for applying the color ink. With this change, a fusion time of the metallic ink is ensured, and the occurrence of an image defect is suppressed.

A printer includes a head, a lamp, a first sensor, and a processor. The head is configured to eject photocurable ink onto the object to be printed. The lamp is configured to irradiate light onto the object to be printed. The first sensor is configured to detect a temperature inside the printer. The processor causes the first sensor to acquire the temperature inside the printer. The processor acquires, based on the print data, a duty ratio indicating a printing ratio when ejecting the ink onto an ejection region of the object to be printed. The processor increases a number of times of a flushing operation compared to a predetermined reference number of times, when the acquired duty ratio is a low duty ratio lower than a predetermined reference duty ratio, and the temperature detected by the first sensor is higher than a predetermined reference temperature.

The present disclosure relates to a process for printing comprising the steps of selecting eight or fewer process colors from a known process ink color set, providing a color channel for the selected process colors from the known process ink color set, providing two or more spot color channels, wherein one or more of spot colors correspond to a non-selected process color of the process ink color set, applying a first ink limit and a first linearization to the one or more spot color channels to produce a color set including the non-selected process color of the known process ink color set, applying a second ink limit and a second linearization to the one or more spot color channels to produce a color set including the spot color, and optionally printing an image.

An ink jet recording apparatus includes an ink composition, an ink encasement in which the ink composition is encased, a recording head that ejects the ink composition, and a carriage configured to move the recording head back and forth. The carriage carries the ink encasement, with the ink encasement integrated with the carriage. The ink encasement has an ink fill port that opens and shuts as a port through which the ink composition is loaded. The ink composition contains a disperse colorant, with the volume-average particle diameter of the disperse colorant being 110.0 nm or more and 200.0 nm or less, and also contains at least one organic solvent with an SP of 9 or more, with the percentage thereof being 10.0% by mass or more.

An ink contains a coloring material, a water-soluble organic solvent. a compound represented by the following Chemical Formula 1 or Chemical Formula 2, a surfactant containing a first silicone-based compound having an HLB value of from 7.0 to 9.0 and a second silicone-based compound having an HLB value of from 14.0 to 18.0, and water,

##STR00001## where, m represents an integer of from 1 to 4,

##STR00002## where R.sup.1 represents an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 or 8 carbon atoms, or an ally group, 1 represents 0 or an integer of from 1 to 7, and n represents an integer of from 20 to 200.

The present invention relates to [1] a water-based ink containing water-insoluble polymer particles (A), an organic solvent (B) and water, in which a polymer constituting the water-insoluble polymer particles (A) is in the form of a crosslinked polymer; the organic solvent (B) contains a polyhydric alcohol ether; and a rate of change in viscosity of the organic solvent (B) as calculated according to the formula (1) is not more than 140%, and [2] a printing method of printing characters or images on a printing medium using the water-based ink described in the above [1], in which a water absorption of the printing medium per a unit surface area thereof as measured by contacting the printing medium with pure water for 100 milliseconds is not less than 0 g/m.sup.2 and not more than 10 g/m.sup.2.