| 摘要 |
PROBLEM TO BE SOLVED: To provide a convenient and low-cost time indicator which indicates that a desired time period has elapsed, using colors. SOLUTION: The present invention includes a method for indicating the predetermined elapsed time by using colors. An aluminum layer is formed on paper or on a plastic substrate, and reacts to steam or boiling water. The aluminum layer, having a metallic gloss color, is changed to a clear and colorless mineral known as boehmite (AlOOH). The thickness of the aluminum layer is changed by the predetermined time; setting time can be changed, in response to the thickness; and the time indicator is provided and enables the elapsed desired time to be confirmed by color. COPYRIGHT: (C)2008,JPO&INPIT
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