1. Field of the Invention
The present invention relates to an aqueous ink composition containing a color microparticle dispersion and an ink jet recording method using the ink composition, and, particularly, to an ink composition having excellent printing quality and stability and to an ink jet recording method using the ink composition.
2. Description of the Related Art
With the spread of computers in recent years, ink jet printers are widely used for printing on, for example, paper, films and clothes not only in offices but also in homes. As ink jet recording inks, oil-based ink, aqueous ink and solid ink are known. Among these inks, aqueous ink is advantageous in view of easy production, handling ability, odor, safety, and the like and therefore is in the mainstream.
However, although many of the foregoing inks use a water-soluble dye which dissolves in a molecular state and therefore have the advantages of high transparency and color density, since the dye is water-soluble, these inks have poor water resistance. When these inks are used to print on so-called normal paper, bleeding is caused, leading to a poor print quality and light fastness. Further, these inks have the drawback that in recording paper provided with an ink receiving layer containing a porous inorganic microparticle thereon (hereinafter sometimes referred to as “photographic quality paper”), image preservability is significantly deteriorated by the effects of oxidizing gas (e.g., SOx, NOx and ozone).
Under such circumstances, aqueous inks using pigments or disperse dyes for the purpose of solving the above problem are proposed in Japanese Patent Application Laid-Open (JP-A) Nos. 56-157468, 4-18468, 10-110126, 10-195355 and the like.
U.S. Pat. No. 6,031,019 discloses an ink including a polymer impregnated with a dye. However, the diameter of an ink particle is relatively large and continuous printing performance using the ink is not sufficient.
However, in the case of these aqueous inks, although water resistance is improved to some extent, there is still a problem in that these inks lack pigment preservation stability and dispersion stability of disperse dye; consequently an ink outlet may be easily clogged. Moreover, there is the problem that in photographic quality paper, the above ink using pigments or dyes has poor permeability, and the aforementioned pigments or dyes are easily peeled off from the surface when rubbed.
On the other hand, methods of encapsulating dyes in urethane or polyester dispersion particles are proposed in JP-A Nos. 58-45272, 6-340835, 7-268254, 7-268257 and 7-268260. However, in the case of ink jet inks obtained according to the above methods, color tone, color reproducibility and color fading stability are insufficient. Further, in the case of printing on photographic quality paper, abrasion-resistant characteristics with respect to, for example, an eraser is insufficient.
U.S. Pat. No. 6,025,412 discloses colored fine particles formed by chemically bonding a dye to a polymer. However, since it is difficult to prepare a monomer having a dye skeleton, the particles cannot widely be used.
As mentioned above, there has not yet been provided an ink composition comprising a color microparticle dispersion which has excellent handling characteristics, acceptable odor and safety characteristics, has sufficiently small particle diameter of dispersion particles, and is superior in dispersion stability and preserving ability of a dispersion, such that there is no clogging at the end of a nozzle, has excellent jetting stability has high color developing ability and excellent color tone (hue) regardless of a type of paper used, has excellent ink permeability even in the case of using the aforementioned photographic quality paper, is also superior in water resistance after printing, and particularly image preserving ability and abrasion resistance after printing and enables high-quality recording at a high density.
USPTO Backgrounds
USPTO Backgrounds