Patent ID: 7812068

Claim:
A recording ink comprising: a colorant, a wetting agent, a surfactant, a penetrating agent, and water, wherein when the moisture evaporation rate of the recording ink which is represented by the following numerical formula 1 is less than 30%, the viscosity elevating rate of the recording ink which is represented by the following numerical formula 2 is 10 or less; when the moisture evaporation rate is 30% to 50%, there appears a point at which the viscosity elevating rate is more than 500; and when the moisture evaporation rate is less than 30%, the average particle diameter of the colorant in the recording ink is two times or less the initial average particle diameter of the colorant before the moisture evaporation of the recording ink, Moisture evaporation rate(%)=[( W A −W B )/ W A ]×100 <Numerical formula 1> wherein W A represents an initial mass (g) of the recording ink before the moisture evaporation and W B represents a mass (g) of the recording ink after the moisture evaporation, Viscosity elevating rate= V B /V A <Numerical formula 2> wherein V A represents an initial viscosity (mPa·s) of the recording ink before the moisture evaporation and V B represents a viscosity (mPa·s) of the recording ink after the moisture evaporation.