Patent ID: 8474964

Claim:
An ink comprising: a plurality of polymers; and carbon black, wherein the plurality of polymers comprise a polymer A having an acid value of 200 mgKOH/g or more and 300 mgKOH/g or less and a polymer B having an acid value of 80 mgKOH/g or more and 180 mgKOH/g or less, and the weight average molecular weight of the polymer A is larger than the weight average molecular weight of the polymer B, and the carbon black has a DBP oil absorption of 75 mL/100 g or less and a specific surface area of 200 m 2 /g or more, and each of -Ph-(CH 2 ) n —NH 2 and -Ph-(CH 2 ) n —NH—R serving as a functional group is bonded to surfaces of carbon black particles, wherein Ph represents a phenylene group, n represents an integer of 0 to 2, and R represents the polymer A.