| 摘要 |
<p>PURPOSE: To obtain an ink having such excellent drying resistance that no crystals or the like deposit on the part of ink delivery even when this part is exposed to air for a long time by mixing a pigment of a specified particle diameter with a humectant comprising a mixture of urea with ethyleneurea in a specified mixing ratio and water. CONSTITUTION: A water-based ink essentially consisting of a pigment having a maximum particle diameter of 0.3μm or below, a humectant and water, wherein the humectant comprises urea and ethyleneurea in a ratio of 1/3 to 5/1. This ink has such an excellent drying resistance that no crystals deposit on the part of ink delivery such as the penpoint of a writing utensil or the nozzle of an ink jet printer even when this part is exposed to air for a long time. This is presumably because the evaporation of water from the penpoint is markedly suppressed because of the easy formation of hydrogen bonds among urea, ethyleneurea and water molecules and the inhibition of ink delivery by the pigment particles otherwise encountered when the ink is thickened when the part of the ink delivery is exposed to air for a long time can be alleviated because of the reduction of the maximum particle diameter to 0.3μm or below.</p> |
