Abstract:
Disclosed is a cyan ink used for an ink set comprising four kinds of aqueous inks, namely a cyan, magenta, yellow and black ink, respectively containing water, a water-insoluble colorant and a plurality of water-soluble organic solvents including a good solvent and poor solvent for the water-insoluble colorant. The cyan ink is characterized in that the ratio B1/A1 between the poor solvent and the good solvent in the cyan ink is within a specific range; the water-soluble solvent having the largest Ka value among the water-soluble organic solvents is a poor solvent; and the ratio B/A between the poor solvent and the good solvent contained in an arbitrary aqueous ink other than the cyan ink in the ink set and the above-described ratio B1/A1 satisfy a certain relation. Such a cyan ink has a sufficiently large area factor even with a small amount of ink droplet, and enables to obtain an image having high image density. This cyan ink is also excellent in shelf life stability and bronzing resistance.
Abstract:
An ink having a sufficiently large area factor even with a small amount of ink droplet and being excellent in shelf life stability is disclosed which enables to obtain an image having excellent image density. Specifically disclosed is a cyan ink used for an ink set comprising four kinds of aqueous inks, namely a cyan ink, a magenta ink, an yellow ink and a black ink, respectively containing at least water, a water-insoluble colorant and a plurality of water-soluble organic solvents including a good solvent for the water-insoluble colorant and a poor solvent for the water-insoluble colorant. The cyan ink is characterized in that the total amount A1 (% by mass) of the good solvent contained in the cyan ink and the total amount B1 (% by mass) of the poor solvent contained in the cyan ink are in a ratio B1/A1 of not less than 0.5 and not more than 3.0; and the water-soluble solvent having the largest Ka value determined by the Bristow method among the water-soluble organic solvents is a poor solvent.
Abstract:
A water-based ink of the present invention comprises water, a plurality of different water-soluble organic solvents, and a water-insoluble coloring material, wherein the above water-soluble organic solvents consist of a good solvent to the above water-insoluble coloring material and a poor solvent to the above water-insoluble coloring material, and the total amount (% by mass) of the good solvents in the ink is represented by A and the total amount (% by mass) of the poor solvent in the ink is represented by B, the ratio of A to B ranges from 10:5 to 10:30 both inclusive, and when the respective Ka values of the above water-soluble organic solvents are determined by the Bristow method and compared with each other, a water-soluble organic solvent having the largest Ka value is the poor solvent. The pigment ink has a sufficiently large area factor even with a small amount of ink and provides an image of high OD.
Abstract:
The present invention aims to provide an ink which has a sufficiently large area factor even in a small ink droplet quantity and can obtain images having a high image density, and further has a superior storage stability. According to the present invention, a cyan ink is provided which is used in an ink set having four kinds of aqueous inks consisting of a cyan ink, a magenta ink, a yellow ink and a black ink in which each ink comprises at least water, a water-insoluble coloring material, and a plurality of water-soluble organic solvents having a good medium or good mediums for the water-insoluble coloring material and a poor medium or poor mediums for the water-insoluble coloring material, wherein, the ratio B 1 /A 1 is from 0.5 or more to 3.0 or less, where A 1 denotes the total content (mass%) of the good medium based on the total mass of the cyan ink and B 1 denotes the total content (mass%) of the poor medium based on the total mass of the cyan ink, and a water-soluble organic solvent which shows the maximum Ka value among the respective Ka values of the plurality of water-soluble organic solvents as determined by the Bristow method is the poor medium.
Abstract:
Disclosed is an aqueous ink comprising at least water, a plurality of water-soluble organic solvents and a coloring material. The coloring material is a pigment, and, it contains a pigment particle having at least one ionic group bonded to a surface of the pigment particle directly or via another atomic group. The plurality of water-soluble organic solvents have a good medium or good mediums for the pigment and a poor medium or poor mediums for the pigment. The poor medium does not solvate perfectly or substantially the pigment. The ionic group undergoes perfectly or substantially no ionic dissociation in the poor medium. Also, among the respective Ka values of the plurality of water-soluble organic solvents as determined by the Bristow method, the Ka value of the poor medium is maximum.
Abstract:
A water-based ink of the present invention comprises water, a plurality of different water--soluble organic solvents, and a water-insoluble coloring material, wherein the above water-soluble organic solvents consist of a good solvent to the above water-insoluble coloring material and a poor solvent to the above water-insoluble coloring material, and the total amount (% by mass) of the good solvents in the ink is represented by A and the total amount (% by mass) of the poor solvent in the ink is represented by B, the ratio of A to B ranges from 10:5 to 10:30 both inclusive, and when the respective Ka values of the above water-soluble organic solvents are determined by the Bristow method and compared with each other, a water-soluble organic solvent having the greatest Ka value is the poor solvent. The pigment ink has a sufficiently large area factor even with a small amount of ink and provides an image of high OD.
Abstract:
Disclosed herein is an ink set comprising a black ink and a color ink and being suitable for an ink-jet recording apparatus comprising a common recovering means for a black ink-ejecting means and a color ink-ejecting means, wherein the black ink comprises particles of self-dispersing carbon black having at least one anionic hydrophilic group at the surface thereof in an aqueous medium, and the pH of the color ink is higher than the pH of the black ink.