Patent ID: 7037365
Filing Date: 2006-05-02
Classification: C09B,C09D

Abstract:
1. An ink set comprising a plurality of inks different in hues, wherein the plurality of inks includes a black ink containing a coloring agent that is a dye having: a λmax of 500 nm to 700 nm; a half value width of 100 nm or more in an absorption spectrum of a dilute solution normalized to an absorbance of 1.0; and a forced fading rate constant of 5.0×10 −2 [hour −1 ] or less, in which the forced fading rate constant is decided by dissolving and/or dispersing the dye in an aqueous medium to form an ink composition for ink jet recording, printing the ink composition 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, wherein the dye is compound represented by the following general formula (1): wherein A, B and C each independently represents an aromatic group or a heterocyclic group, which may be substituted, m is an integer of 1 or 2, and n is an integer of 0 or more, with the proviso that at least one of A, B and C is a heterocyclic group which may be substituted.