Patent ID: 7914138

Claim:
An ink for ink-jet recording comprising a coloring agent, wherein the coloring agent contains a dye, the ink further contains a marker, the marker contains at least one of a dye and a pigment, and has a detector absorption peak for detecting the marker at a wavelength that is different from a wavelength of the maximum absorption peak of the coloring agent, and the coloring agent and the marker are contained in the ink in amounts that satisfy the following conditions (I) to (III): (I) about 1.2≦A 2 /A 3 ; (II) color difference (ΔE)≦about 3; and (III) about 0.001≦A 2 ≦about 5 in terms of a measurement optical path length of 1 mm, where A 2 denotes an absorbance at the wavelength of the detector absorption peak of the marker, A 3 denotes a baseline absorbance at the wavelength of the detector absorption peak of the marker, Δ E ={(L* 1 −L* 2 ) 2 +(a* 1 −a* 2 ) 2 +(b* 1 −b* 2 ) 2 } 1/2 , L* 1 denotes an L* value of the ink, L* 2 denotes an L* value of a control ink, a* 1 denotes an a* value of the ink, a* 2 denotes an a* value of the control ink, b* 1 denotes a b* value of the ink, b* 2 denotes a b* value of the control ink, and the control ink is an ink having the same composition as a composition of the ink except that water is used instead of the marker.