Water-base ink for ink jet recording
AssigneeSeiko Epson Corporation
InventorHiroshi Itoh
Life of this patent
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Abstract
An ink composition is disclosed which comprises a water-insoluble colorant, a water-soluble organic solvent, and water, the ink composition being substantially free from any dispersant, the water-insoluble colorant being in a dispersed state in the ink composition. The ink composition of the present invention, despite the fact that no dispersant is used, is stable and can provide a good print. A process for producing the above ink composition is also disclosed. According to this process, a stable ink composition can be produced without the step of dispersing a colorant by means of a ball mill or the like.
Claims20
A water-base ink composition comprising a water-insoluble colorant, a water-soluble organic solvent, and water,
- the ink composition being substantially free from any dispersant,
- the water-insoluble colorant having a solubility in water at 20.degree. C. of not more than 1% by weight and being soluble in the water-soluble organic solvent,
- the water-insoluble colorant being in a dispersed state in the ink composition.
A process for producing a water-base ink composition comprising the steps of:
- dissolving a water insoluble colorant in a water-soluble organic solvent to form a colorant solution with the colorant being present in a dissolved state in the colorant solution in an amount of 1 to 30% by weight;
- and
- adding water to the colorant solution and mixing to precipitate fine particles of the colorant such that the fine particles of the colorant are present in the ink composition as a dispersion and not as an emulsion of droplets formed of the colorant and the organic solvent, the colorant and water-soluble organic solvent being included in the colorant solution and the water and optional other components being added to the colorant solution in respective amounts such that the colorant is present in the ink composition in an amount of 0.5 to 15% by weight and the water-soluble organic solvent is present in the ink composition in an amount of 1 to 35% by weight.
Dependencies are inferred from the claim text.