| 摘要 |
PROBLEM TO BE SOLVED: To obtain a water-base ink that can alleviate the wear and deformation of the ball socket due to ball rotation and give a nonskipping writing even after long-distance writing by mixing water with an acrylic acid/alkyl methacrylate copolymer, a coloring pigment, and carbon black in an amount smaller than a specified amount. SOLUTION: The amount of the carbon black used is below 0.1 wt.% based on the entire weight of the ink. The carbon black is exemplified by any one of carbon backs having a pH of 6 or below, a pH of 6-9, and a pH of 9 or above in view of surface activity and is exemplified by ant one furnace black, channel black thermal black, and lamp black in view of production process. The acrylic acid/alkyl methacrylate copolymer acts as a water-soluble thickener in the ink and is exemplified by PEMULEN TR-1 (trade mark, a product of Goodrich Co.). It is desirable that the copolymer is used in an amount of 0.10-0.50 wt.% based on the entire weight of the ink, and that the pigment is used in an amount of 0.1-40 wt.% based on the entire weight of the ink. |
