| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a color-changeable ballpoint pen which has an excellent writing performance even after the passing of time and is also capable of permanently forming handwriting that can be discolored or decolored, and which is excellent in utility and convenience. <P>SOLUTION: In the color-changeable ballpoint pen, an ink storing tube provided with a ballpoint pen tip holding a ball at the end is filled with ink which contains at least water and a dye which is discolored or decolored by a reducer and has pH in the range of 1-5. The ball is made of cemented carbide which contains cobalt of 2.0 wt.% or less. <P>COPYRIGHT: (C)2008,JPO&INPIT |
