Ink jet image forming method and ink jet recording apparatus

An ink jet image forming method for forming an image by applying inks of plural colors to plain paper with an ink jet recording system,

• wherein when the total amount of the inks applied to a fundamental matrix for forming the image is 5.0 μl/cm2 or less, and the duty of at least one ink of a color of the inks applied to the fundamental matrix is 80% duty or more, the application of the at least one ink to the fundamental matrix is conducted within a range of 1 msec or more and 200 msec or less and at plural timings within the range, and the amount of the at least one ink applied at each timing is controlled to 0.7 μl/cm2 or less, and
• wherein the at least one ink is applied in a fixed amount of 0.5 pl or more and 6.0 pl or less, comprises a self-dispersion pigment, an organic carboxylic acid salt, water and a water-soluble compound having a hydrophilicity-hydrophobicity coefficient of 0.26 or more as defined by the equation (A), and has a surface tension of 34 mN/m or less,
• Hydrophilicity-hydrophobicity coefficient=[(Water activity of a 20% aqueous solution)−(Molar fraction of water in the 20% aqueous solution)]/[1−(Molar fraction of water in the 20% aqueous solution)]. Equation (A):

An ink jet recording apparatus equipped with a recording head for forming an image by applying an ink of a color to plain paper with an ink jet recording system,

• wherein the ink is applied in a fixed amount of 0.5 pl or more and 6.0 pl or less, comprises a self-dispersion pigment, an organic carboxylic acid salt, water and a water-soluble compound having a hydrophilicity-hydrophobicity coefficient of 0.26 or more as defined by the equation (A), and has a surface tension of 34 mN/m or less, and
• wherein the apparatus comprises a control mechanism for controlling the application of the ink such that when the total amount of the ink applied to a fundamental matrix for forming the image is 5.0 μl/cm2 or less, and the duty of the ink applied to the fundamental matrix is 80% duty or more, the application of the ink to the fundamental matrix is conducted within a range of 1 msec or more and 200 msec or less and at plural timings within the above range, and the amount of the ink applied at each timing is controlled to 0.7 μl/cm2 or less,
• Hydrophilicity-hydrophobicity coefficient=[(Water activity of a 20% aqueous solution)−(Molar fraction of water in the 20% aqueous solution)]/[1−(Molar fraction of water in the 20% aqueous solution)]. Equation (A):

An ink jet recording apparatus equipped with a recording head for forming an image by applying inks of plural colors to plain paper with an ink jet recording system, wherein

• wherein the apparatus comprises a control mechanism for controlling the application of the inks such that when the total amount of the inks applied to a fundamental matrix for forming the image is 5.0 μl/cm2 or less, and the duty of at least one ink of a color of the inks applied to the fundamental matrix is 80% duty or more, the application of the at least one ink to the fundamental matrix is conducted within a range of 1 msec or more and 200 msec or less and at plural timings within the range, and the amount of the at least one ink applied at each timing is controlled to 0.7 μl/cm2 or less, and
• wherein the at least one ink is applied in a fixed amount of 0.5 pl or more and 6.0 pl or less, comprises a self-dispersion pigment, an organic carboxylic acid salt, water and a water-soluble compound having a hydrophilicity-hydrophobicity coefficient of 0.26 or more as defined by the equation (A), and has a surface tension of 34 mN/m or less,
• Hydrophilicity-hydrophobicity coefficient=[(Water activity of a 20% aqueous solution)−(Molar fraction of water in the 20% aqueous solution)]/[1−(Molar fraction of water in the 20% aqueous solution)]. Equation (A):