Patent ID: 7022170

Claim:
An ink for ink jet recording, which comprises a dye having: a λmax in an aqueous solution of from 390 nm to 470 nm; and a I(λmax+70 nm)/I(λmax) ratio of not more than 0.4, in which I(λmax) is the absorbance at λmax and I(λmax+70 nm) is the absorbance at (λmax+70 nm), the dye being dissolved and/or dispersed in an aqueous medium, and the dye is represented by formula (1), A-N═N-B (1) wherein A and B each independently represents a heterocyclic group which may be substituted, wherein the ink has a forced fading rate constant of not greater than 5.0×10 −2 [hour −1 ], in which the forced fading rate constant is decided by printing the ink on a reflection type medium, thereafter measuring a reflection density through a Status A filter, specifying one point having a reflection density (D B ) in an yellow region of 0.90 to 1.10 as an initial density of the ink, forcedly fading the printed matter by use of an ozone fading tester that can regularly generate 5 ppm of ozone, and determining the time taken until the reflection density reaches 80% of the initial density, and the total amount of a cation in said ink except for a monovalent metal ion, a hydrogen ion, an ammonium ion, an organic quaternary nitrogen ion and an ion produced by the proton addition to a nitrogen atom in a basic organic material is 0.5 wt % or less.