abstract |
The present invention relates to an aqueous ink having a surface tension of 34 mN/m or less including a self-dispersion pigment and water. In the aqueous ink, the self-dispersion pigment has a plurality of pKa values that are 8.0 or less. Assuming that the lowest pKa value among the plurality of pKa values is pKa 1 and the highest pKa value among the plurality of pKa values is pKa 2 , pKa 1 and pKa 2 satisfy Mathematical formula (1), and the pH value of the aqueous ink satisfies Mathematical formula (2). |