Patent ID: 7083664

Claim:
An inkjet color ink comprising: an aqueous medium; at least one yellow dye having a λmax of from 390 nm to 470 nm and an [I(λmax+70 nm)/I(λmax)] ratio of an absorbance I(λmax+70 nm) at λmax+70 nm to an absorbance I(λmax) at λmax of not more than 0.4; and at least one dye having a λmax of longer than 470 nm and not longer than 750 nm, the at least one yellow dye and the at least one dye being at least dissolved or dispersed in the aqueous medium, wherein in case the ink is printed on a reflection medium so as to form a stepwise density, when a light having a wavelength of a λmax of the ink in a yellow region of 390 nm to 470 nm is illuminated to the printed medium, whose reflection spectrum of the light is measured by a spectrophotometer, and a point giving a reflection spectrum such that a reflection density, D B , at the λmax of the ink in the yellow region, is from 0.90 to 1.10 is selected, a reflection density at a λmax of the ink in a region of longer than 470 nm and not longer than 750 nm at the point is defined as D X , and the printed medium is discolored by force using an ozone discoloration tester capable of always generating 5 ppm of ozone, a forced discoloration rate constant determined from a time when each of the reflection densities D B and D X becomes 80% of an initial density is defined, and both of the rate constants are not more than 5.0×10 −2 hour −1 .