| 摘要 |
According to one embodiment, an aqueous pigment ink includes water, a pigment, and a water-soluble polymeric compound. The pigment is contained in the aqueous pigment ink in an amount of less than 5 wt %. The aqueous pigment ink has viscosities (mPa·s) measured at 25° C. using a cone-plate type viscometer and satisfying the following relationships: 0≦̸(VB−VA)/VB<0.05 VC/VA≧1.5 3 mPa·s≦̸VA≦̸15 mPa·s wherein VA represents a viscosity measured at a rotation speed of 50 rpm, VB represents a viscosity measured at a rotation speed of 2.5 rpm, and VC represents a viscosity measured at a rotation speed of 50 rpm after adding calcium chloride in an amount of 0.5 wt % of the aqueous pigment ink.
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