| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a writing utensil effective for learning, taking notes or the like, in which the vision of a printed image or a written image under normal temperature range can be prevented from developing by forming a reversible thermally discolored hiding handwriting layer for covering the printed image or the written image and which is equipped with a thermally discolored reversible appearing and disappearing function, which bares the image under a visible state by discoloring the handwriting image with the frictional heat developed by scratching the handwriting image with a rubbing body. <P>SOLUTION: The writing utensil with the thermally discolored reversible appearing and disappearing function can form the handwriting with a lightness value of color density of not more tahn 4.5 in color development and a lightness value of not less than 5 in discolored state by the frictional heat by using an ink prepared by dispersing 10-45 wt.% of the specified reversible thermally discolored micro-capsulated pigment having a high temperature side perfectly discoloring temperature in the range of 30-80°C in a water-based medium, and has the rubbing body for the handwriting. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
