Patent ID: 8029122
Filing Date: 2011-10-04
Classification: C09D

Abstract:
1. A recording ink comprising: water; a water-soluble organic solvent; a surfactant; and a carbon black having a hydrophilic group on a surface thereof, wherein at least a part of a terminal of the hydrophilic group on the carbon black is substituted with an alkali metal, wherein a quantity of the alkali metal contained in the recording ink is from 100 ppm or more to 1500 ppm or less, wherein the carbon black releases humic acid in an aqueous dispersion of the carbon black, which is recovered from the recording ink, a concentration of the humic acid released in the aqueous dispersion containing 20% by mass of the carbon black is expressed with a maximum absorbance at a wavelength of 230 nm to 260 nm, and the recording ink has the maximum absorbance of 5.0 to 20.0 at the wavelength of 230 nm to 260 nm.