| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a marking method for applying marking such as the display of materials to a plastic molding without depending on printing so that there occurs no troubles even if the marking is contacted with contents such as foods, and it does not disturb recycling. <P>SOLUTION: A plastic material is previously mixed with a bright-colored oxide of transition metal such as TiO<SB>2</SB>(with white) by an amount in the range where troubles are not caused on the molding of the plastics, e.g., by about 3 wt.%, and then, the molding is performed. A laser beam is applied to the molding to change the valence of the transition metal, and it is changed into a dark-colored oxide, in this case, into Ti<SB>2</SB>O<SB>3</SB>(with purple) or TiO (with black), so that desired characters, figures or symbols are allowed to appear. <P>COPYRIGHT: (C)2004,JPO</p> |
