Field of the Invention
The present invention relates to an ink and an ink cartridge and an image recording method employing the ink.
Description of the Related Art
Heretofore, in an image recording method, an ink containing a self-dispersible pigment as a coloring material has been used for the purpose of increasing the optical density of images. In particular, it is known that a self-dispersible pigment having a phosphonic acid group bonded directly or through another atomic group to the surface (hereinafter also simply referred to as a “phosphonic acid-based self-dispersible pigment”) easily provides images particularly high color development properties (Japanese Patent Laid-Open No. 2012-233163). Japanese Patent Laid-Open No. 2012-233163 describes combining a self-dispersible pigment having a phosphonic acid group, a resin having a specific acid value, and a specific surfactant to thereby obtain an image having high color development properties.
However, the ink containing a self-dispersible pigment has high color development properties of images but has had a problem that the scratch resistance of images is low. Then, an examination for improving the scratch resistance of images by further blending polyurethane resin particles in the ink containing a self-dispersible pigment has been made (PCT Japanese Translation Patent Publication No. 2005-515289). PCT Japanese Translation Patent Publication No. 2005-515289 describes that the scratch resistance of images is improved by an aqueous ink jet ink containing a self-dispersible pigment and a polyurethane resin having an acid group.