| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To indicate a state of preservation of a product preserved for a long period under a circumstance where a state of preservation of many products changes rapidly in the course of production, transportation, and delivery. <P>SOLUTION: A plurality of biodegradable plastic sheets 11, each selected to have a given thickness, are so stacked that a biodegradable plastic sheet 11 at an upper layer covers a biodegradable plastic sheet 11 at a lower layer. This lamination is left as it is in a given environment so that the sheets 11 degrade and delaminate sequentially from a sheet 11 at an upper layer. In an environment that accelerates degradation, a sheets 11 at a lower layer is exposed faster. The order of an exposed sheet 11 from the top layer indicates load imposed by an environment where the sheets 11 are placed in. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
